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MAR- 1 8- 1932
The Lake Sangchris Study: Case History of an Illinois Cooling Lake
Jon Larimore
. Tranquilli EDITORS
.LINOIS (ilNSTITUTE OF NATURAL RESOURCES
14L HISTORY SURVEY DIVISION MGN, ILLINOIS
VOLUME 32, ARTICLE 4 AUGUST 1981 i
f us ISSN 0073—4918 itturail History Survey
i The Lake Sangchris Study i Case History of an "inois Cooling Lalce
^3ldon Larimore li A. Tranquilli (FIC EDITORS
: F ILLINOIS
I IS INSTITUTE OF NATURAL RESOURCES
i IRAL HISTORY SURVEY DIVISION UPAIGN, ILLINOIS
VOLUME 32, ARTICLE 4 AUGUST 1981 STATE OF ILLINOIS ILLINOIS INSTITUTE OF NATLTRAL RESOURCES BOARD OF NATURAL RESOURCES AND CONSERVATION FRA^fK Beal, M.S.. Chairman. Vacant, Biology, H. S Gutowsky, . Chemutry, E, PhD Walter Hanson. MS , Engmeermg, Lorin L Nevunc.Jr.. Ph.D., Forestry; L.L, Sloss, Ph.D.. Geology. W.L, Everjtt, E.E., Ph.D.. Represerumg the President of the University of lUmois. John C. Guyon. Ph.D., Representing the Prestderit of Southern llhnots University
NATURAL HISTORY SURVEY DIVISION, Champaign. Illinois SCIENTIFIC AND TECHNICAL STAFF PaulG. Risser. Ph.D. Chief Alice K. Adams, Secretary to the Chief
Section of Aquatic Biology Joseph V, Maddox, Ph.D.. Associate Entomologist
Robert W Gorden. Ph D . Aquatic Biologist and Head Robert D. Pausch. Ph.D.. Associate ErUomologist D. Homer Buck, Ph.D., Aquatic Biologist RoscOE Randell, Ph.D.. Associate Entomologist, Extension
William F. , William Childers. PhD Aquatic Biologist G. Ruesink. Ph.D . Associate ErUomologist R. Weldon Larimore. Ph.D., Aquatic Biologist John K. Bouseman, M.S.. Assistant Entomologist
Richard F. Sparks. Ph.D . Aquatic Biologist Catherine Eastman, Ph.D . Assistant Entomologist Robert C. Hiltibran, Ph.D.. Biochemist Allan Felsot, Ph.D.. AsststarU Entomologist Allison Bricham, Ph.D., Associate Aquatic Biologist Eu Levine, Ph.D.. AsststarU Entomologist Warren U. Bricham, Ph.D., Associate Aquatic Biologist Luis R. Zavaleta. Ph D,. AsststarU Entomologist Ketiirah Reinbold, Ph.D., Associate Aquatic Toxtcologist Arthur Acnello, MS, AsststarU Specialist. Extension
John A. Tranquilli, Ph D,. Associate Aquatic Biologist Charles MacMonecle. M.S . AsststarU Specialist, Extension Ken Li'BINskj, Ph.D.. Assistant Aquatic Biologist Kevin Steffy, Ph.D.. AsststarU Specialist. Extension
David P. Philipp. Ph.D . Assistant Aquatic Biologist Steven Troester, M.E., Assistaru Systems Engineer Henry H, Seacle.Jr,, Ph D,. Assistant Aquatic Biologist Jean G. Wilson, B.A,, Supervisory Assistaru
Ted W. Storck. Ph.D , AssistarU Aquatic Biologist Lester Wei, Ph.D., Assistaru Professional Scientist Bruce Taubert. Ph.D.. Assistant Aquatic Biologist Charles G Helm. M.S.. AsststarU Supportive ScierUtst Michael Wiley. Ph.D., Assistant Aquatic Biologist Stephen Roberta, B.S., AsststarU Supportive Scientist
RichardJ. Baiir, M.S , Assistant Supportive Scientist John T. Shaw. B.S,, Assistant Supportnv Scientist Eugene SoNs.yunior Professional Scientist Sue M Hale, yumor Professional Scientist Jana Lee Waite, M.S.jfumor Professional Scientist William Lamp. Research Associate
Stephen W. Waite, MS, Research Associate Gerald A Schultz, Ph.D , Research Associate Dale Burkett. B.S., Research AssistarU Michael Jeffords, Ph.D., Field Entomologist Robert Larry W, Coi'Tant, MS. Research Assistant J. Barney. M.S . Research AsststarU Jeffrey Koppelman. B.S.. Research Assistant Tzu SuAN Chu. M.S.. Research AssutarU Samuel Lynch, B.S., Research Assistant Jenny Kogan. M.S., Research Assistant Susan Dennis Newman, M S , Research Assistant Post. B.S,, Research Assistaru
Lance Perry. M.S.. Research AsststarU Gail Kampmeier. MS . Research Techructan Todd Powless. M.S., Research Assistant Michael McGuire. M.S., Research Technician Thomas Skelly. M.S., Research Assistant Jo Ann Auble. Technical AsststarU
Michael Wallendorf, B S . Research Assistant EiXEN Brewer, MS , Computer Programmer Frank Zumwalt. M.S., Research Assistant Joan Traub, Clerk Typist II
Joan Brower. B.S . Technical Assistant Christina Clark, B.S.. Technical Assistant Section of Faunistic Surveys and Insect indent if ication
E. , Robert Davis, B.S , Technical AsststarU Wallace LaBerge. Ph.D Insect Taxonomtsl and Head Bill DiMOND, B.S.. Technical Assistant Larry M Page. Ph.D.. Taxonomtsl Kathryn Ewing, B-S.. Technical Assistant George L. Godfrey. Ph.D.. Associate Taxonomist DwicHT Garrels, M.S., Technical Assistant John D, Unzicker, Ph.D.. Associate Taxonomist Rebecca Grosser. B.S., Technical AsststarU [>onald W Webb. Ph.D.. Associate Taxonomist David Aleta Holt, B S,, Technical AsststarU J, Voegtlin, Ph.D , AssutarU Taxonomist Jeanine Kasprowicz, B.S.. Technical AsststarU Bernice p. Sweeney. yumor Professional Scientist
Shirley Lowe. B S.. Technical Assistant Eugene Miliczky. M S . Research Assistaru Philip Mankin. B.S., Technical Assistant Steven Miller, B.S., Technical AsststarU Section of Wildlife Research Sue Peratt, Technical Assistant Glen C Sanderson, PhD . Wildlife Specialist and Head Brenda Peters, Technical Assistant Frank C Bellrose. ScD,, Wildlife SpeciaUsl Michael Retzeh. MS, Technical Assistant Harold C Hanson, Ph.D. Wildlife Specialist Thomas Rice. M.S., Technical Assistant
WiLUAM R. Edwards, PhD , Wildlife Ecologtst Jens Sandbercer, M.S., Technical Assistant Jean W Graber. Ph D.. OmUhologist Michael Sandusky, B,S,. Technical Assistant Richard R Graber. Ph D . Ornithologist Paul Shetley, B.S,, Technical Assistant W W. Cochran. Jr. B.S., Associate Wildlife Specialist Stephen Sobaski. B.S,, Technical Assistant Charles M. Nixon, MS., Associate Wildlife Ecologtst Pam Tazik. MS., Technical A ssutant Ronald L Westemeier. MS . Associate Wildlife Ecologtst Jeffrey VAN Orman, B.S., Technical Assistant Stephen P Havera. Ph D.. Assistaru Wildlife Ecologtst
Gary L. Warren. B.S , Technical Assistant Ronald P, Larkin, Ph D.. AssutarU Wildlife Ecologut MarkJ. Wetzel. B.S., Technical Assistant Richard E, Warner, PhD . AssutarU Wildlife Ecologut Ruth Wagner, yumor Technical Assistant Susanne G. Wood. Ph.D . AssutarU Wildlife Ecologut
John E. Buhnerkempe. MS , AssutarU Supporin-e ScierUut Section of Botany and Plant Pathology Robert D. Crompton, yumor Professional Saenttst
Claus Grunwald, Ph.D , Botanist and Head Ronald E. Duzan. yumor Professional Scientut
Eugene Himelick, , PhD Plant Pathologist Cynthla G Jackson, B. A, .yumor Professional Scientist Neely, Dan PhD,, Plant Pathologist James W Seets, yumor Professional Scientut
ScHOENEWEiss. , D F. Ph.D PlarU Pathologist Eva Stecer, BA .yumor Professional Scientut Crane, J. Leland Ph.D., Mycologist John S Lohse. Ph D,. Research AssutarU
Anton G. Endress, Ph.D , Associate Botanist H. Kathleen Archer, BS . Technical AssutarU Kenneth R, Robertson. Ph.D., Associate Botanist Elizabeth A McConaha. Techrucal AssutarU Betty Nelson, Assistant Supportive Scientist Gregory A. Perkins, BS,, Techrucal AssutarU Gene E. REiD.yumbr Professional Scientist James Chelsvig. BS . Field A ssutant James E. Sergent, Greenhouse Superintendent Teresa A. Schuli-er, BS . Laboratory AssutarU Robert A. Harrison, Technical Assistant Judith Eilbracht, Clerk Typut II David R. Moore. B.S-, Technical Assistant Supporting Services Section of Economic Entomology Phylus S, Clark, Mailing and Dutnbution Sentces William H Luckmann. PhD . Entomologist and Head Dorothy M. Diehl. AccoutU Technician 1 James E. Appleby, Ph.D., Entomologist WiLMA G DiLLMAN. Property Control and Trust Accounts EdwardJ. Armbrust, Ph.D., Entomologist Patty L Duzan. Payroll and Personnel Marcos Kocan. Ph D,. Entomologist Robert O, Ellus, AssutarU for Operations Ronald H. Meyer, Ph.D.. Entomologist Larry D, Gross. Operatioru AssutarU Stevenson Moore, III, Ph.D., Entomologist. Extension Chris Rohl, Operatioru AssutarU Michael E. Irwin. Ph.D., Associate Entomologist Jacque Sanders, ClerkTyput II Donald E. Kuhlman. Ph.D.. Associate Entomologist. Extension Melvin E. Schwartz, Fiscal Officer Publications and Public Relations Technical Library Robert M. Zewadsiu. M.S.. Technical Editor Doris L. Sublette, M.S.L.S,, Technical LtbraTian Shirlev McClellan, B.S.. AssutarU Technical Editor Monica Lusk, Library Technical Assistant Llovd LeMere. Technical Illustrator Leslie Woodbum, Technical Photographer
CONSULTANTS AND RESEARCH AFFILIATES; Aquatic Biology. James R, Karr. Ph.D.. Professor of Ecology, Ethology and Evolution. University of Illinois: BoTA^fY and Plant Pathology. Iean D. Schoknecht. Ph.D.. Associate Professor of Life Sciences. Indiana State University. Terre Haute. Systematic Entomolocv, Roderick. R. Irwin. Chicago. Illinois. Wildlife Research. WillardD, Klimstra. Ph.D., Professor of Zoology and Director of Cooperative Wildlife Research. Southern Illinois University. Parasitology. Norman D. Levine. Ph.D.! Velertruiry Professor of Parasitology. Veterinary Research and Zoology and Director of the Center for Human Ecology. University of Illmois; Entomology, Robert L. Metcalf. Ph.D.. Professor of Biology and Research Professor of Entomology. University of Illinois; and Gilbert P Waldbauer. Ph.D. . Professor Entomology. University Illinois. Statistics. Horace Norton. of of W. Ph.D. . Professor of Statistical Design and Analysis, University of Illinois. Preface
Lake Sangchris, in central Illinois, Limnological data were urgently needed; provides cooling water for the Kincaid so the company contracted with Generating Station, a coal-fired electric Limnetics, Inc., Milwaukee, Wisconsin, generating plant that was developed by to conduct limnological baseline studies. Commonwealth Edison Company of Limnetics, Inc., studied the lake from Chicago in the early 1960's. June 1971 to June 1972 and submitted a During the years 1961 through 1963 report to the company entitled A several engineering reports were prepared Limnological Survey of Lake Sangchris, for Commonwealth Edison Company Illinois dated December 1972. In May regarding the construction of Kincaid 1973 Limnetics, Inc., filed another Generating Station and its cooling lake. report with Commonwealth Edison, A By July 1963 the company had decided to Second Limnological Survey of Lake proceed with construction, starting the Sangchris, Illinois, based on studies following summer. The first electrical conducted during October 1972. power was produced at the plant in June Additional unpublished reports that 1967. have served as background materials in the Legal issues have arisen along with the present study include fish sur\e\'S by the development of Kincaid Generating Division of Fisheries, Illinois Department of Station. Even before the construction of Conservation, in October 1971 and 1972. the lake, questions were raised These reports are on file in the division's concerning public use of cooling office in Springfield. A report by William reservoirs. This led to several years of Anderson, Illinois Natural History negotiations with the Illinois Department Survey, on the mercury levels in the flesh of Conservation and an ultimate of Lake Sangchris fish was submitted to agreement in 1969 for the management Commonwealth Edison in 1972. The of the lake and surrounding lands as a Illinois Natural History Survey also recreation facility. Until this time completed a report to Commonwealth Commonwealth Edison's only necessary Edison in 1973 entitled Comparative legal licenses had been those to construct Limnological Literature Survey — Sang- a dam across Clear Creek and for the chris Lake, which compared information construction and operation of a sewage on Lake Sangchris with available treatment facility. Passage of the Illinois information on five reservoirs of similar Environmental Protection Act of 1970 size, geographical location, and general and the adoption of water-quality hydrological characteristics. Soon after regulations under the Illinois Pollution the beginning of the present study in Control Board in 1972 made it necessary August 1973, Mr. Edward Juracek, for the company to gather environmental biologist with Commonwealth Edison, information in support of the lake as a presented a report entitled Lake waste-water treatment facility.' Sangchris: Case History of an Illinois
'Dr. Richard G. Monzingo. Aquatic Biologist, 203(i)(l-4) or to obtain regulatory relief from these Commonwealth Edison Company, has provided this standards. updated account of the regulatory history of Lake In PCB R75-2, Commonwealth Edison proposed Sangchris. a regulation that would exempt artificial cooling On July 18, 1974, the Pollution Control Board lakes (impounded) from otherwise applicable (PCB) of the State of Illinois ruled (in PCB thermal standards of Rule 203(i)( 1 -4) and requested 73-245/248 consolidated) that Lake Sangchris is not specific thermal limitations for Lake Sangchris. On set a "treatment works" but is. in fact, "waters of the 29 September 1975, the Board ruled instead to state." The Board determined that an operating standards by which individual artificial cooling permit was required with respect to discharges from lakes could receive specific thermal limitations. In the Kincaid Generating Station into Lake Sangchris addition, the Board did not approve the specific and that as a condition to the issuance of the thermal limitations for Lake Sangchris because the permit. Commonwealth Edison Company would be limitations were not based on historic temperatures required to demonstrate compliance with the in the lake. thermal standards contained in Chapter 3, Rule In April 1976, Commonwealth Edison proposed Cooling Lake as part of a workshop on temperature preferences, potential energy production and thermal effects; dangers to the biological system, benefits the papers read at that workshop were to plant and animal communities, and published in January 1974 by Limnetics, causes of environmental degradation Inc. Juracek's report contained much of associated with power production; (2) the information mentioned in the construction of a fish production model preceding paragraphs and served as a from the large accumulation of physical- review of the development of the power chemical-biological data; and (3) a plant, its lake, and the legal statutes comparison of fish production in Lake associated with the Kincaid Generating Sangchris with that of Lake Shelbyville, a Station. nearby flood control reservoir. This work four- volume Under contract with Commonwealth has been completed, and a final report. a Cooling Lake Edison Company, the Illinois Natural Evaluation of has been published by EPRI History Survey studied this cooling lake Fishery, (1979-1980). However, those investigations ecosystem intensively from August 1973 be completely separated through August 1977 to determine the cannot from the work supported by Common- effect of the thermal discharge and and reported here.^ combustion byproducts on the local wealth Edison environment. Investigations included The investigative work was carried detailed studies of water quality, out by an interdisciplinary team of plankton, aquatic macrophytes, clams, specialists. Administration and overall benthos, fish, fish harvest or creel, water- coordination of the project were handled fowl, trace metals, and pesticides. Some at the Illinois Natural History Survey studies (water quality, benthos, clams, headquarters in Urbana, while field and aquatic macrophytes) were activities were coordinated through a terminated in 1976, and others were field station at Kincaid, a few miles from initiated to consider the distribution of the lake. Most of the fishery biologists larval fishes in the cooling loop and the were based at the field station; other effect of the impingement and team members were based in Urbana entrainment of fish by the power plant. where more extensive laboratory and History InJune 1 975 , the Illinois Natural analytical facilities were available. Survey received additional support from the The Lake Sangchris Project enjoyed Electric Power Research Institute(EPRI)of consistent support and cooperation from Palo Alto, California, to expand investigations officials of Commonwealth Edison at Lake Sangchris. The expanded work Company, especially from John H. consisted of three parts: (1) a study of the Hughes, Head of the Environmental relationship between the fisheries and the Quality Section; Edward Juracek, James physicochemical conditions associated with power production, including fish On 11 May 1978, the Board approved Commonwealth Edison's 203(i)(5) demonstration the following specific thermal standards based on (PCB 77-309). This demonstration (similar to the historic fact: the effluent temperature shall not USEPA 316 (a) demonstration) incorporated the exceed 99°F (SVC) during more than 7 percent of records of the previous three hearings, including all the hours in the 12-month period ending with any of the data from the Illinois Natural History Survey month and shall at no time exceed H1°F (44°C) studies. (PCB 7611). In December 1976. an economic The studies the INHS performed also provided impact statement prepared by the Illinois Institute data to support the 316(a) (thermal) and 316(b) of Environmental Quality indicated that both (intake) demonstrations to the USEPA. The 316(a) economic and environmental considerations demonstration was accepted on II May 1977 and favored the proposed standards. On 13 October the 316(b) demonstration was approved on 2 1977, the Board approved the proposed standards. January 1979. The Board commented that although the records in R76-2 and 76-11 contained other useful reports 'Fishery investigations were continued at Lake concerning Lake Sangchris. the most valuable Sangchris in 1979, when funding for fishery testimony came from studies performed by the management research was received for a 3 year Restoration Illinois Natural History Survey (INHS). period from Federal Aid in Fish C. Rice, and Richard Monzingo, project Dr. Louis A. Krumholz, University of managers during the investigations; and Louisville, critically reviewed the Bud Stauffer, Charles PoHto, and Ed manuscripts. We sincerely appreciate. his Swenson, Kincaid Generating Station valuable technical suggestions and superintendents. Commonwealth Edison recognize that his skills and editorial also contributed substantially toward the discipline contributed greatly to the final publication costs. We sincerely appreciate development of this monograph. the help that made the investigations Manuscripts were also reviewed by possible and pleasant. various members of our Siu^ey staff. The final We are also indebted for the help we editing of the entire set of manuscripts received from many University of Illinois was done by Robert M. Zewadski, and Eastern Illinois University students in Technical Editor, and by Shirley both field and laboratory studies, other McClellan, Assistant Technical Editor. members of the Illinois Natural History Technical Illustrator Lloyd LeMere did Survey staff, and Illinois Department of much of the drafting, and various staff Conservation personnel stationed at Lake members contributed photographs. Sangchris State Park and in the Fisheries Jana Waite, Administrative Assistant in the Division. Section of Aquatic Biology, carefully We acknowledge the help of Dr. typed the final copy. To these, our Loren Wheeler, presently at the supportive associates, we extend sincere University of Arkansas, for his statistical appreciation for their careful work. advice with reference to the Corbicula Careful readers will notice some defi- paper, and Dr. Clyde Anderson, ciency in up-to-date literature, resulting presently at Michigan State University, from the time required to edit and print for his statistical help on the fish such a large monograph. Please notice population dynamics, fish tagging, and the submission date at the bottom of the radiotelemetry papers. first page of each chapter.
R. Weldon Larimore Principal Investigator, Lake Sangchris Project Aquatic Biologist, Illinois Natural History Survey
John A. Tranquilli Project Leader, Lake Sangchris Project Associate Aquatic Biologist, Illinois Natural History Survey CONTENTS The Lake Sangchris Project 279 R. Weldon Larimore and John A. Tranquilli
Water Quality in a Cooling- Water Reservoir 290 Allison R. Brigham
Phvtoplankton Dynamics in a Cooling- Water Reservoir 320 Robert L. Moran
Effects of Cooling Lake Perturbations upon the Zooplankton Dynamics of Lake Sangchris 342 Stephen W. Waite The Benthic Macroinvertebrates from the Cooling Lake of a Coal-Fired Electric Generating Station 358 Donald W. Webb
Reproduction, Growth, Distribution, and Abundance of Corbicula in an Illinois Cooling Lake 378 Herbert Dreier and John A. Tranquilli
AftUATic Macrophytes in Lake Sangchris 394 Robert L. Moran
Population Dynamics of the Lake Sangchris Fishery 413 John A. Tranquilli, Richard Kocher, and John M. McNurney
Food Habits of Some Common Fishes from Heated and Unheated Areas of Lake Sangchris 500 and Donald R. Halffield, Michael J. Sule, John M. McNurney, Jr.
First- Year Growth and Feeding of Largemouth Bass in a Heated Reservoir 520
Michael J. Sule
Results of a Multiple-Objective Fish-Tagging Program in an Artificially Heated Reservoir 536 John A. Tranquilli, John M. McNurney, and Richard Kocher
Radiotelemetry Observations on the Behavior of Largemouth Bass in a Heated Reservoir 559 John A. Tranquilli, Donald W. Dufford, R. Weldon Larimore, Richard Kocher, and John M. McNurney
Behavioral Thermoregulation of Largemouth Bass and Carp in an Illinois Cooung Lake 585
Valerie J. Smith and John M. McNurney Lake Sangchris Creel Survey: 1973-1975 594 John M. McNurney and Herbert Dreier
Distribution and Abundance of Larval Fishes in Lake Sangchris (1976) 615 Harry Bergmann
Impingement and Entrainment of Fishes at Kincaid Generating Station 631 Wesley Porak and John A. Tranquilli
Waterfowl Studies at Lake Sangchris, 1973-1977 656 Glen C. Sanderson and William L. Anderson
Distribution and Accumulation of Trace Metals at a Coal-Fired Power Plant and Adjacent Cooling Lake 691 Kenneth E. Smith and William L. Anderson
Index 731
Section Aquatic This report is printed by authority of the State of Illinois. It is a contribution from the of Biology, Section of Faunistic Surveys and Insect Identification, and Section of Wildlife Research of the Illinois Natural History Survey. (18657 -4M 8 81) i5 1
development. (Aeri Photomosaic of the Lake Sangchris area, showing the intensive agricultural photographs courtesy of the Illinois Department of Transportation.) The Lake Sangchris Project
R. Weldon Larimore and John A. Tranquil
INTRODUCTION to the environment. The efficiency of that exchange depends on the local Reservoirs constructed specifically for climate, the morphometry of the lake the dissipation of waste heat constitute a basin, the exposure of the lake surface to relatively new aquatic environment that wind, the volume of water moving creates both problems and attractive through the plant and through the lake, potentials. The most apparent environ- the amount of heat carried away mental problems are those associated and from the condenser tubes. The efficiency with waste heat from a production of the heat-exchanging process is also process; the most obvious benefits are related to several peculiar physical recreational, especially the unique characteristics of water, such as its opportunity for open- water fishing in a specific heat, heats of vaporization and northern climate during winter. To eval- fusion, and density at different uate the detriments and benefits of a temperatures. cooling-lake ecosystem, one must the physical attributes of this consider In most lakes, the primary source of man-made system before attempting to heat is radiant energy from the sun, with understand the more complex biological lesser amounts from groundwater seepage relations. Those relationships include the or through conduction from the air or trophic structure of the aquatic entire from the basin materials. By design, an ecosystem. additional source to a cooling lake is the functions their These physical and heat that must be removed in power biological systems have associated been production to convert spent steam to intensively investigated at Lake water. Although part of the radiant heat Sangchris, an 876-ha cooling lake that penetrates the water mass and is serves a coal-fired, steam-driven electric transmitted into deeper waters by generating station in central Illinois. conduction and convection, heat from There it has been found, for example, both the sun and the power plant is that the plankton population was directly distributed throughout the lake associated with the water currents ecosystem by the force of wind on the produced by pumping, the benthos was water surface and, in a cooling lake, by influenced by the modification of bottom the circulation produced by the substrates in the discharge canal, and fish withdrawal and discharge of cooling temperature distribution was affected by water at the power plant. gradients within the cooling loop. Before these and other relations are fully In the process of exchanging heat reported in the series of papers presented from the power plant to the environment,
in this monograph, it seems necessary to the cooling lake serves as a heat sink that point out the physical factors that absorbs and stores heat for various ultimately drive the associated biological lengths of time. The high specific heat of system within a cooling lake. water permits the absorption of large
Any cooling lake is a massive heat amounts of heat with relatively modest exchanger that takes waste heat from the increases in water temperature. Although
plant's condenser system and transfers it some heat is transmitted by conduction into the lake sediments, the total heat Dr. R. Wcldon Larimore is an Aquatic Biologist capacity of most lakes is primarily and Dr. John A. Tranquilli is an Associate Aquatic proportional to the water volume, Biologist in the Section of Aquatic Biology, Illinois Natural History Survey. because the water has the high specific
279 280 Illinois Natural History Survey Bulletin Vol. 32. Art. 4
heat and capacity to absorb heat. The fetch in a flat basin. With other heat storage capacity of most lakes in conditions being similar, heat loss
temperate regions is significantly reduced through evaporation is more rapid from during the summer by stratification, high-altitude lakes with lower barometric caused by differential density layers that pressure than from low-altitude lakes. serve as barriers to the mixing of warm The decrease in evaporation with surface waters into the cooler deep increased salinity makes a brackish-water waters. In a cooling lake, where currents coastal lake a less efficient heat dissipator produced by pumping prevent thermal than a freshwater lake and suggests layers from being maintained, such reduced heat transfer in cooling lakes in stratification may never be established or which salts have accumulated. may last for only short periods. If part of For heat to be discharged from a lake the thermal discharge from the power into the atmosphere through any plant enters the deeper waters of the lake, dissipating process, the heat must be the deeper layer may warm at nearly the delivered to the surface layers. Since same rate as the surface waters, so that convection currents are generally weak
there is less difference in density from top and since water is a relatively poor heat
to bottom and mixing is facilitated. conductor, wind-induced circulation is Heat acquired by a lake from the sun the primary transport mechanism and or from electric power production is depends largely on lake morphology and largely dissipated through evaporation the exposure of the lake surface to winds. and back radiation. Lesser amounts of Winter ice on lakes virtually heat are lost through conduction to the eliminates evaporation and permits only air and to basin materials. The enormous small heat and water losses through amounts of heat involved in the sublimation. It is, however, of little evaporation of water (539.6 calories per concern in cooling lakes in the Midwest, gram of water) keep our temperate and because open water is maintained tropical lakes from being much warmer throughout the year by the heated dis- than they are in the summer and establish charge. a lake as an efficient heat exchanger for Heat gains and losses not only dissipating heat from either natural determine a lake's annual heat budget sources or from industrial processes. and its effectiveness in dissipating waste The rate of evaporation (and thus of heat from a power plant, but also impose heat loss) increases with increased a strong influence on the lake's biological temperature and with reduced vapor systems. Primary and secondary pressure, barometric pressure, and production are directly proportional to salinity. The increase in evaporation with water temperature within the range of increase in temperatures moderates or temperature in which metabolism occurs damps thermal maxima: as summer normally. Each organism has an optimal temperatures rise or as more thermal temperature for maximal growth as well wastes are introduced, the loss of heat as limits of tolerance for high and low
through evaporation is greatly increased. temperatures above and below which it Back radiation, on the other hand, is cannot survive. But the controls of virtually independent of temperature and biological systems are not restricted to thus assumes a higher percentage of heat temperature alone. dissipated at progressively lower Stress, whether due to temperature temperatures. extremes or one of the many other The greater the exposure of the lake's physical or chemical parameters that surface to air movements (wind), the modify physiological and behavioral greater will be the heat dissipation. A functions, is relatively simple to detect lake with high banks, banks covered with and measure in individual organisms and tall trees, or a surface area arranged in usually can be determined for any many coves will not be as efficient a heat species, even though each life state may exchanger as an open lake with a long have to be considered distinctly. Prob- Aug. 1981 Larimore & Tranquilli: The Lake Sangchris Project 281 lems of a much greater complexity are electric generating plant modifies the encountered in measuring stress in a daily and seasonal physical relations men- community composed of many kinds of tioned in the preceding paragraphs. organisms of different life stages. For Discharged heat, impingement of instance, a temperature change might organisms on intake screens, entrainment modify diatom photosynthesis, which of organisms through the pumps and con- would alter the forage base of the gizzard denser tubes, and water currents produc- shad and thus affect the forage base for ed by pumping are the primary opera- the largemouth bass. Such interactions in tional influences at Lake Sangchris and communities of plants and animals at most cooling lakes. should be the primary concerns in The quantity of heat discharged and evaluating environmental disturbances. the amount of water moving through the The elevated temperature of a cooling lake plant determine the total temperature may impose short-term stresses on an change produced by the electrical individual plankter or fish, but the most generating station. Increased pumping important consideration is whether such rates yield reduced temperatures along stresses cause measurable changes in the with higher intake velocities and thus trophic structure or function of the increase the impingement and entrain- aquatic community. ment of aquatic organisms. The higher Under the stress of an environmental discharge velocities result in greater disturbance, individual organisms may mixing of the heated waters. die, adjust (acclimate) to the new Most industries, and especially power conditions, or behaviorally adapt by plants, have scheduled shutdowns for moving away. If the natality, mortality, maintenance and unscheduled ones for metabolism, or longevity is affected, the emergency repairs. The continuity of relative abundance, growth rate, or plant operations plays an important role behavioral activity, and thus the place of in the physicochemical characteristics of that organism in the community, will be a cooling lake. Effects of a shutdown are altered. The environmental modification most drastic during winter, when may not only have direct influences on organisms acclimated to warm discharge the individual of a particular species, but waters suddenly become exposed to much can also have a more subtle effect by colder water as the thermal discharge changing an animal's food resources, the stops but pumping continues to move abundance of its predators, or the cold water into the system. occurrence of pathogens. From man's Lake Sangchris experienced many point of view, changes in the community shutdowns during the 4-year period of are not necessarily detrimental. An study. Although such irregularities attractive sport fish may displace an caused only minor difficulties in the unattractive rough fish, or a species interpretation of overall temperature entirely new to the community may be effects, sudden changes in waste heat able to survive and thrive in the modified discharge did permit observations of the habitat. As an example, the threadfin most severe thermal conditions. While shad, a species with a low temperature temperature shock may cause mortality threshold, may be desirable for man's among aquatic organisms, more often it interests because of its value as a forage simply modifies the immediate habitat base for sport fishes, whereas other and produces subtle behavioral changes species, such as pathogenic fungi or in the animals. protozoa or blue-green algae that thrive at elevated temperatures, may be highly INQUIRY undesirable. THE Industrial production of waste heat When this investigation began, there has a direct influence on the physical were many questions regarding the effects systems that function naturally in a lake. of thermal discharges and combustion At Lake Sangchris, the operation of the byproducts on the fauna and flora of 282 Illinois Natural History Survey Bulletin Vol. 32, Art. 4
cooling lakes and the lands surrounding of the impoundment, as often them. Those questions could most readily occurs in unheated reservoirs? be answered by careful examination of a Is fish growth enhanced or depressed? relatively confined, closed-cycle cooling Do fish in heated and unheated areas system, such as Lake Sangchris. The of a cooling lake have similar
following is a partial list of questions feeding habits? toward which this investigation was How does the thermal effluent affect directed. the timing of reproduction by fishes? What factors govern water quality in What effect does the effluent have on a cooling lake ecosystem? spatial, temporal, and vertical How is the annual temperature re- distribution of fish larvae? gime affected by power plant Is the standing stock of fish in the lake operation, and what is the effect significantly reduced by impinge- of the circulation and mixing of ment of individuals on the waters on their physical and traveling intake screens or by chemical constituents? entrainment of fish eggs and Is photosynthesis inhibited at high larvae through the condensers? temperatures, and do blue-green Are fish kills common as a result of algal forms become dominant? cold shock and/or gas supersatur- What aquatic vciscular plants are pres- ation, and are the fishes in cooling ent, and how are their distribu- lakes under stress and thus more tion and biomass affected by the susceptible to infestation by thermal discharge? parasites or infection by disease Are the phytoplankton and zooplank- organisms? ton communities in heated and unheated areas quantitatively and Which fish species occur most often in qualitatively similar? the fisherman's catch, in which areas and seasons? Is zooplankton production enhanced or depressed by the thermal Are catch rates by anglers reduced or
effluent, or is normal seasonal enhanced by the thermal effluent? variation reduced? How are airborne particulates from the plant stack distributed in What inhibits benthic production in power the land water surrounding the discharge canal? and the generating facility? How does the diversity of benthic or- Are heavy metals, such as mercury, ganisms in cooling reservoirs being magnified as they pass compare with that of unheated through the food chain, and are reservoirs in the region? they being concentrated in the Is the life history of the Asiatic clam, predatory fish? Corbicula, altered in a cooling How are the behavior and migration of lake? the large numbers of waterfowl Is the standing crop of fish in cooling attracted to cooling lakes altered? lakes within the range expected Do the high transmission lines em- for reservoirs of similar size in the anating from power plants Midwest? present hazards to flying birds? How do fish populations respond to Are waterfowl that ingest slag ad- the thermal effluent — are they versely affected, and what is the attracted or repelled — in different effect on the lake of nutrient seasons? loading by these large bird Will fish travel relatively long populations? distances in a thermal gradient to select preferred temperatures? The strength of the Lake Sangchris Does production of fish in cooling case history lies in the intensive sampling lakes decline with increasing age program simultaneously carried out over Aug. 1981 Larimore & Tranquilli: The Lake Sangchris Project 283
a 4-year period by a team of investigators as the water moves through the middle approaching the problems of ecosystems (discharge) arm toward the dam and then by looking at all trophic levels. into the west (intake) arm, a 16.1-km (10-mile) course to the plant's cooling LAKE SANGCHRIS AND THE water intake structure. Condenser KINCAID GENERATING cooling water is drawn from the lake by STATION, LOCATION AND four pumps, each with a capacity of 160,000 gpm (10.1 mVsec) or a total DEVELOPMENT capacity of 640,000 gpm (40.4 mVsec).
The Kincaid Generating Station is The intake pumps are located 18.3 m located in central Illinois 24 km (15 below the surface of the lake. A skimmer miles) southeast of Springfield. It was wall prevents the circulation of water developed by Commonwealth Edison from the upper 6.1 m of the water Company from 1963 through 1966 to column (Porak & Tranquilli 1981: Fig. supply electricity to northeastern Illinois. 2). The intake canal is approximately 6.1
The plant is adjacent to Peabody Coal m.deep, 1,219 m long, and 30 m wide. Company's No. 10 mine, which supplies Depending on the plant loading and the fuel for steam production. Lake the amount of water being pumped, the Sangchris, constructed to provide cooling recirculating water moves through the water for the plant's condenser system, cooling loop in about 11 days. The was formed by damming Clear Creek, a cooling loop constitutes approximately 64 small tributary to the South Fork of the percent of the lake's area. The eastern Sangamon River. Clear Creek flowed (control) arm of the lake receives heat from south to north. Above where it was from the plant only through back the divided into dammed stream was circulation at its confluence with the three branches, so that the resulting lake discharge arm. was composed of three relatively long and Gross electrical output for narrow arms that converged northward the Kincaid Generating Station from toward the dam (Fig. 1). September 1973 through August 1977 Over 5,000 ha of land were acquired generally showed a dicyclic annual trend for the plant and its cooling lake. The with peak power output during winter lake covers 876 ha, a 30-m buffer zone and summer and reduced loads during around the lake comprises approximately autumn and spring (Fig. 2). Two 275 ha, and the the state company gave exceptions to this generalization occurred of Illinois ha to for recreation 607 be used as a result of scheduled maintenance and and wildlife habitat. plant, slag The repair work on one of the two units in the pond ha), and adjacent agricultural (32 winter of 1974-1975 and on both units for fields occupy the remaining area. a 46-day period during the summer of 1976. Production outages of both units THE GENERATING STATION AND for 3 or 4 days at a time were not COOLING SYSTEM uncommon during the 4-year study period (Fig. 2), but outages for more than The Kincaid Generating Station be- 1 week occurred only twice, during the gan commercial operation in 1967. The summer of 1976 for about 6 weeks and for plant, positioned between the southern 8 days during November 1976. ends of the western and middle arms of
Lake Sangchris, is a coal-fired facility While maximum power production with two 616-megawatt steam turbine and a continuous heat load throughout units. Water carrying the waste heat is the study period would have been the discharged 1.5 m below the surface most desirable experimental situation, through a 4,6-m diameter pipe into a the production record of Kincaid canal (1,100 m long and 30 m wide) that Generating Station was typical of coal- flows into the middle (discharge) arm of fired units, and the changing power plant
the lake. Waste heat is dissipated rapidly loading factor may have been more stress- 284 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Aug. 1981 Larimore & Tranquilli: The Lake Sangchris Project 285 ful to the biota of the cooling lake than a Fifteen to 60 m of unconsolidated drift, steady load would have been. loess, and alluvium overlie Pennsylva- nian bedrock (Willman et al. 1967). Two THE LAKE BASIN major coals, Springfield (No. 5) Coal and
The Lake Sangchris basin is near the Herrin (No. 6) Coal, underlie the area. center of Illinois (Fig. 1), with 89° 29' Each varies up to 2 m in thickness in that west longitude bisecting the basin that area. Herrin Coal is mined for the extends from 39° 39' north latitude at the Kincaid Generating Station. dam southward to 39° 29' north latitude. The soils surrounding the lake proper The 18,880 ha (73 square miles) drainage are dark and moderately permeable, basin lies mostly within northwestern having developed from moderately thick Christian County, and only a small loess. Immediately surrounding the lake portion of the basin extends westward are three main soil types— Illiopolis silty into Sangamon County. clay loam, Ipava silt loam, and Bolivia The basin is in the northwestern part silt loam — overlain with 2-3 m (7-10 feet) of the Springfield Plain, a physiographic of upland loess. Farther south of the lake province that crosses central Illinois and in the lake's upper drainage basin, southwest of the Shelbyville Moraine. Herrick silt loam and Virden silty clay The province has a flat to rolling surface loam are overlain with about 2 m (5-7 occasionally incised by shallow valleys. feet) of loess (Fehrenbacher et al. 1950).
Aerial view of Kincaid Generating Station and the disctiarge canal. 286 Illinois Natural History Survey Bulletin Vol. 32, Art. 4
These are highly productive soib, and when properly farmed, are not particularly erodable.
Before inundation the soils of the lake basin were light colored and moderately permeable and had developed under timber vegetation from moderately thick loess. Hickory gravelly loam (sides of the valley) and Radford silt loam (bottom of the valley) constitute the major soil types (Fehrenbacher et al. 1950). These soils are only moderately fertile and are subject to serious erosion.
Central Illinois, including the Sangchris basin, has a typical continental climate with sharp seasonal changes, including warm summers and cold winters (NOAA Environmental Data and < Information Service 1972 and 1978). Average monthly temperatures range from 25»C in July to - S^C in January (Fig. 3). Although the summers are humid, there E are no distinct wet and dry seasons. Mean monthly precipitation varies considerablv.
as can beseen in Fig. 4 ; it ranges from a little over 10 cm in May and June to slightly less to than 5 cm in January, with an annual average of 89 cm. Wind velocities of more than 64 km/ hour are not uncommon for brief periods in most months, with prevail- ing winds southerly during most of the vear C3 g and northwesterly only in late fall and to o spring. Such winds have a profound effect on the stability of the exposed waters of Lake Sangchris, which has low banks and relatively little tree growth
along its shoreline.
THE LAKE Lake Sangchris was formed during 1963-1966 by damming Clear Creek, a small tributary of the South Branch of the Sangamon River. The stream and its Q. tributaries were low gradient and collectively had a mean flow of 1.2
0) m'/sec (U.S. Environmental Protection $ CO Agency 1975). o 5 The lake began to fill as the dam was being finished, and water reached the spillway level (elevation 178.3 m above sea level) in June 1966, thus completing
(0001 > A«a/H«l
JAN FEB. MAR. APR. HAY JUNE JUL. AUG, SEPT, OCT. NOV. DEC.
Fig. 3. —Mean monthly air temperatures near Lake Sangchris, 1 973-1 977, and for the combined 40 years before 1973 (labeled MEAN).
1974 r20
CD I— I— D_
LU
1 1 1 1 1 1 1 1 1 r
JAN. FEB. MAR. APR. MAY JUNE JUL. AUG. SEPT. OCT. NOV. DEC.
Fig. 4. —Mean monthly precipitation near Lake Sangchris, 1973-1977, and for the combined 40 years before 1973 (labeled MEAN). 288 Illinois Natural History Survey Bulletin Vol. 32, Art. 4
Table 1. — Physical characteristics of Lake Sangchris.
Characteristic Measurement
Surface area 876 ha (2,165 a) Maximum depth 13.7 m (45 ft) Average depth 4.6 m (15 ft) Volume 37.4 X lO'm' (1.320.74 x 10«ft>) Shore length 160 km (93 miles) Maximum effective length 4.950 m (16,240 ft) Maximum effective width 1,170 m (3,840 ft) Area of drainage basin 18,880 ha (46,652 a) Spillway elevation (msl) 178.31 m (586.0 ft) Mean hydraulic retention time 438 days Volume development index 1.08 Surfacearea-to-volume ratio 0.23 m-'(0.07 ft"') Shoreline development index 14.23
9 m. Although not a deep lake, Lake feeding Lake Sangchris (1.2 m'/sec) Sangchris has an average depth of 4.6 m results in a mean hydraulic retention time
(Table 1), a depth similar to those of of 438 days (U.S. EPA 1975). This is a many central Illinois reservoirs of very low rate compared with those of comparable size. The volume develop- several nearby reservoirs, such as Lake ment index, which compares the volume Shelbyville (131 days). Lake Springfield of the lake to the volume of a cone with a (176 days), and Lake Lou Yaeger (121 base equal to the area of the lake and a days). The low flow through Lake Sang- height equal to the maximum depth, chris not only limits heat dispersal by suggests a bowl-shaped basin. The ratio internal currents, compared with such between surface area and volume (Table heat dispersion in reservoirs with more 1) further suggests a somewhat flattened rapid flushing rates, but also virtually basin. In general, the higher that ratio, eliminates loss of heat from the lake by the greater the cooling capacity of lakes discharge over the dam and thus any of the same volume, since most of the thermal effects on the receiving waters
heat dissipation is at the water's surface. below the lake.
The morphology of Lake Sangchris is, Although Lake Sangchris has a maxi- if not unique, at least nearly ideal as a mum effective length of less than 5,000 m cooling lake and for thermal studies. It and a maximum effective width of slight- permits efficient heat dissipation through ly over 1,000 m (Table 1) only at the a relatively long cooling loop, minimizes dam, the effective exposure to the wind is the thermal effects on biological systems maximized by the long, nearly parallel by having many side coves and an arms of the lake. And, too, the dendritic unhealed arm, and provides a convenient surface arrangement, with a relatively size and arrangment for experimental high shoreline development value of work. 14.23, expressing the relation of total shoreline to a circle with a circumference REFERENCES CITED equal to the area of the lake, suggests Fehrenbacher. J.B.. R.S. Smith, and R.T. Odeix. protection from straight sweeps of winds. 1950. Christian County soils. University of In actuality, the fmgerlike arrangement Illinois Agricultural Experiment Station Soil
of the surface area exposes the waters to Report 73. 64 p. relatively long fetches, increasing wave National Oceanic and Atmospheric Administra- tion Environmental Data and Information action and heat exchange with the Service. 1972. Local climatological data: atmosphere. Springfield. Illinois. National Climatic The relatively small flow of water Center, Asheville, N.C. Aug. 1981 Larimore & Tranquilli: The Lake Sangchris Project 289
Protection Agency. 1975. . 1978. Local climatological data: Spring- U.S. Environmental field. Illinois. National Climatic Center, National eutrophication survey. Report on Asheville, N.C. Sangchris Lake. Christian County, Illinois. Tranquilli. 1981. Impinge- Working Paper No. 314. Corvallis PoRAK, W., and J. A. ment and entrainment of fishes at Kincaid Environmental Research Laboratory, Generating Station. Pages 631-655 in R. W. Corvallis, OR. 15 p. -^ appendices. Larimore andj. A. Tranquilli, eds., The Lake WiLLMAN, H.B., ET AL. 1967. Geologic map of Sangchris study: case history of an Illinois cool- Illinois. Illinois State Geological Survey, ing lake. Illinois Natural History Survey Urbana. Bulletin 32 (4). Water Quality in a Cooling Water Reservoir
Allison R. Brigham
ABSTRACT INTRODUCTION
Lake Sangchris is an 876-ha reservoir Lake Sangchris is an 876-ha constructed from 1963 to 1966 as a impoundment surrounded by flat to cooling water supply for Commonwealth gently rolling agricultural land in
Edison's 1 ,232-megawatt coal-fired Christian and Sangamon counties in
Kincaid Generating Station. Two factors central Illinois (Fig. 1)'. The primary govern existing water quality in the lake: purpose associated with the creation of the operation of the power plant and Lake Sangchris was to provide adequate urban and agricultural runoff from the condenser cooling water for the coal-fired watershed. Kincaid Generating Station of Common- wealth Edison Company, a plant with a The annual temperature regime is net generating capacity of 1,232 affected by plant operation as waste heat megawatts. Maximum cooling water flow is dispersed and eliminated through the through the plant is 640.000 gpm, or lake. More important, however, is the approximately 900 mgd. As water flows beneficial side effect of plant operation through the plant, the water temperature on water quality: the lake does not rises betwen 7° and 10°C. achieve permanent thermal or chemical Water flow around Lake Sangchris stratification during summer and winter. follows a circular pattern. The power Because of the circulation and mixing of plant is located between the west and water in the lake induced by plant middle arm's of the lake at the extreme operation, the deleterious effects of southern end adjacent to Illinois Route stratification (anoxic waters; formation 104. Cooling water is taken into the plant of decomposition gases, such as ammonia at the southern end of the west arm, and hydrogen sulfide) are uncommon to pumped through the plant, and absent. In addition, waste heat is dissipated quickly. Generally, discharged into the southern end of the middle arm. This continuous pumping approximately 70 percent of the added action creates a flow which proceeds heat is lost by the time the water mass has north along the middle arm to the flowed halfway around the cooling loop. dam area, then south along the western arm of Chemical input to the lake is derived the lake to the intake canal, a total primarily from surrounding urban and distance of approximately 16 km. Flow agricultural areas. During periods of high time varies from 7 to 11 days, depending surface runoff (spring thaw and following upon the time of year and the volume of heavy rains), turbidity increases in the plant operation. lake. Chemical constituents associated with The operation of the Kincaid turbidity, such as phosphorus, iron, and Generating Station is the predominant frequently, organic nitrogen, enter the influence upon water quality in Lake lake chiefly via this route. Urban Sangchris, not only because of the influences are highly localized in the additions of waste heat from the southern portion of the east arm of the generation of electricity, but also because lake and are reflected in slightly elevated of the velocity maintained around the organic phosphorus concentrations. cooling loop, resulting from the operation of the pumps. The 32-month Dr. Allison R Brigham is an Associate Aquatic water quality study in the lake was Biologist in the Section of Aquatic Biology, Illinois Natural History Survey. intended to document baseline conditions This chapter submitted in Jan. 1980. to support biological investigations and to
290 Aug. 1981 Brigham: Water Quality 291
LAKE SANGCHRIS ;,
1/ I I I J r / Fig. 1. — Location of Lal by power plant operation (Station 7). METHODS Locations of the sampling stations appear in Fig. 1, Six sites were sampled for Stations were selected (1) to routine water quality analyses. Stations A characterize any potential effect of and B were sampled for water condenser passage upon water quality as temperature and dissolved oxygen water flowed around the cooling loop profiles only. 292 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Sampling was conducted at biweekly than one method is described for any intervals from September 1973 through variable in Standard Methods for the August 1974 and at monthly intervals until Examination of Water and Wastewater, the termination of field sampling in April 13th edition (American Public Health 1976. Approximately 140 water tempera- Association, American Water Works ture and 95 dissolved oxygen profiles were Association, and Water Pollution Control recorded from each Lake Sangchris Federation 1971), the method used is station from September 1973 through listed in Table 1. For continuity, the 13th August 1976. edition was used throughout the study. Sample profiles were collected at all Statistical analyses were performed on stations at these depths from September the variables which constituted the regu- 1973 through August 1975: m, 2 m, 5 lar biweekly or monthly sampling m, and 7 or 8 m, stations 1 and 2; m, 5 program. Descriptive statistics consisting m, 10 m, and 12 m, Station 3; m, 2 m, of the number of measurements, mean, and 5 m, stations 4 and 7; and m, and 2 standard deviation, and minimum and m, Station 5. The 2-, 7- or 8-, and 12-m maximum values are included in Table 2 depths were eliminated for the final for each sampling station. Model I sampling period (September 1975 analysis of variance followed by the through April 1976). modified Duncan multiple-range test Samples were collected with a 4.2- (Kramer 1956) were used to assess the liter plastic Kemmerer bottle. Field relationships among variables at stations measurements included water temp- in the lake. In this way it was possible to erature and dissolved oxygen profiles at determine whether significant differences 1-m depth intervals, hydrogen ion existed among stations for any variable concentration (pH), and free carbon and to demonstrate which stations were dioxide. Laboratory methods are significantly different. References to summarized in Table 1. Where more statistical significance in the text imply Table 1 . — Methods and equipment used in analyzing physical and chemical variables monitored at Lake Sangchris. Variable* Method and Equipment Water temperature (C) Mercury thermometer and thermocouple circuitry Dissolved oxygen YSI Model 51 A DO meter Free carbon dioxide Titrimetric method and nomographic method Hydrogen ion concentration (pH) Sargent-Welch Model PBX meter Total alkalinity (as CaCOj) Standard methods with Metrohm autotitrator EDTA hardness (as CaCO,) EDTA colorimetric method (autoanalyzer) Specific conductance (^tmho/cm at 25 °C) YSI Model SCT meter Total dissolved ionizable solids (as NaCl) By calculation from specific conductance Nitrate (as N) Cadmium reduction method (autoanalyzer) Nitrite (as N) Diazotization method (autoanalyzer) Ammonia (as N) Modified phenate method (autoanalyzer) Organic nitrogen (as N) Total Kjeldahl method (autoanalyzer modified phenate method) Total nitrogen Sum all forms Chloride Argentometric method with Metrohm autotitrator Total phosphorus (as P) Stannous chloride method Soluble orthophosphate (as P) Stannous chloride method Turbidity (Jackson turbidity units) Monitek Model 150 turbidimeter Total iron Phenanthroline method Soluble iron Phenanthroline method Sulfate (as S) Turbidimetric method Organic carbon (total, particulate, dissolved) Direct injection with Oceanography International carbon system Molybdate- reactive silica (as SiOj) Molybdosilicate method shown u mg/ 1 except where other uniti are indicated. ' ' Aug. 1981 Brigham: Water Quality 293 significance at the 0.05 level unless here for all input data. This treatment another level is specified. equalizes variances when variances are Logarithmic transformation wfas used proportional to the squares of the station 11^ • • -1-^ -1-^ a ^ ^ ^ iTi ^^ iTi ^^ -to •—' 'D —- -cj r~"'^-' -GO -co -in '^ "^ -co >-" "— •—' *— •—* ^^O r— C~J C~J ^-i O-l W C^ CJ C~J C^ O'^'CT) CO Oco OcnlOOcoQtn Oco QcoQco QoO pco pco QcO O en Qco Qc^ 2=^ OcO QcO -iM Po^P I'^i'^i'^ii'^ii I I I I I I I I i"i i9i I I I i ^H I l2| inCTir^ooOifjenincNCN-^'CO (XJ Tpi-Ht^tNTf.—(COf-'rt^MCOC lTl3cNCCCN'^C'jTt'C^Tj*CNCCWTpWcOi-irt'CslTj-r-.cnWrt'r*0O>--Tj'CN ^ 00 ^ s ?J , -. .^, , ^ -- O "^ ^2-— o^2'^2^2'^2^2^ O— Oi—« Oi—« O— O— Oi—' O— O.—• O.— ^^ „—'P I -rtH I I I ^ if^oor^"^cncocococ^iLnTj'ir)c^ir3Csicoin'^in-^incoc<^'^in'^r^rt'inc^iincoi>>coc^00 QO^QO^ao^oo|2|S|2|a|2|2|2|2|2|2|2|S|S|2|2|2|S|2|2|SQO„x„oo„Qo^oo„QO^o^^CTi^oo_oo_coco.ooao_abQO I OQOinr^c^OirjiDOr^c^iaO'.O'^ 0l000l000l000^00OiX)C^(XiCJl00aDQ0pQ0a;00U'JCOi^a3W0D'^'" 'cnodcnodoo6o(xi0^oot»QoOooc7^ooQqQor^oopooo^QOCOQopoop^ r^ Qt^ Qt^ oi^ ocd qoo o^^ o^^ o°° o ^ o ^ o^ o<^ O^ O ^ 0°^ O^ O' o 00 o °o o — ^ M c^ ^ -— ._<,_, cH .—>.—. OT) ^ ^ --.-« — (M c5^ c?^ oj" czs" Sis' fiR" o?f &r 55" Sf ^t^^in'^ *^ °'^ ^ ^- ^^o^,— ^. lololololo|olololol2'2l2l2l2l2'2l2l2'SlS •^O00O'fOeTO-^O00O'^OCOO^O-^O'*''-'5n.-'^O0CO^OTfOc0OTHOc0O' r-H -. ;?; 2 s ^ o CO cio 00 ia ,^ \n '-.lis^ ^ °*^. r^t—lO.—'C^.—'O.—-CT) — ,—iin-^co_ito oOr—'COr^tD._^,_ c^.—ir^_r^^_ oo—i_j<—i^cnt— i-H tc O CO iT) CD i? <» S S 8 f: 5 S 5 8 c^ o P ^ P ^. S 8 S So* S^.o^iQ ?^P ^ll.'^ Ji'^ Si ^2°^o^o^o^o^2°^o"^o^o^o^o'*'2^2^2'^2^2^2^2'^2^2 S^2§'SS2S5S§'S'fS oi r^ oq * in P Q . csi oo §i P ^ ' §s ^ 'I- .^ or> (D H "jf- t— CO OO -^ CO ^ CM OO CO tT W M S 6 r* o -^ P- o " ' 294 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 means, typically the case for water Logarithmic transformation is used quality data. The base 10 was used for with positive integers which cover a wride convenience. range. It cannot be used directly for zero. t^ ^ OJ — •— •-- O O ^ o oo tn r^ oo oo c^ oD o oo ^ Cn ^ u5 «-> 25 p"pp"po*-^pp"op*-^p"ppp"po"ppp''pc?50co OcoQ^oQc^ Om 25qOc^ 0cm Q oi 2cN OcoOoo oSn Oc-j Ocg c-cOin OSStn o3'='p^p'='p'^p'^p'='p'=='p'=^p°p'='p'^p'='p°p'=^p p lololololcJlololololcJlololololo'O'O o c:| M r^ r^ ^ !^ ^ on UD ID O iT! m o i^ o i^ O'X^O'TiO^O'^O "^ t^iri ^iri ^r-^ 5^ '^<35 r^ 00 r^cMoc^oj^CM'^or^ixir^ooc^* cy c^i ^ r» 5^ &^ ^r^ Q c'^Tfcoinr^iripiniriin'^irip'rS' Q ^ ^ '^f p f^ 1^ f^ °5 ^ P ^ C^ ^ O (M a OJ is CN 2^2 c^iicMiicMiic^iicsiiic^iS (M is CM CM S CM isCMiscg qcmsc!! i |oq |in |r>. |oq |cm |cm |oq |aq |oq |oq iCM Ip |^ ^. 1 CM<^4'^CM^^(^^^^u:^^lnr^^na6col>^^n!D^^^^ln^rjln^£j^>^--'co CM to — Q — in — in CM in CM CI M r=r t^ r^ a^ !N as ^^ •^ ^ •—• dr> CTi iTi •n in " GDincomr^iDCOin in c;- r- 00 r^ O ^ ^ *^ « '" "" ^ 2 c^ 2 N2cNStNBc^i2^^i 2 cm' 2 CM 2 c^i 2 CM- CN 2 oo 2 on r- 00 QQ 00 CM oo I I °£ I I I ^ CO I oo =^ ic ^. to rfOC^'O'^OoOO O -^ O CO o -^ o Tj- o oo o -* o ^ In -^ CO CO r- in — CM .-' — O Aug. 1981 Brigham: Water Quality 296 and when some of the values are less than number prior to taking the logarithm, as 10, it yields undesirable results. To avoid in transformed Y = logm (Y + 1). Two these problems, 1 is added to each assumptions required of many statistical O op 00 S Q co^^c<^r»r^^ocoCTlln^^a^^-TJ«^^^H[^oo 2'^'—'^'—'"^o^ I ,- I -, I I -., I I «i^ =^ GO Cs) CO O _ ! (A * =^ ; ^ ^ ^ ici I CO O CO O cnoTfoccoTj-ocMO'^O'^ Si: !? tMiSiDobusoocor^ I— N s ^ s s ^ "J" oO CO * CTi CO — CN ^ trj ^ 00 ^ GO oi ^ o »J^ -^ ^ r^ S^" o t^ i-D .— I C?g "^ (N CN I O c^ CO CM -H 00 CsJ ^ ^— CM00cOCM>—"COcMffJOJ-—'C^ 00 qI^i qGO ' 0°^ O"^ O'^ o*^ O*^ O"^ "O' ^7 " " " S 2 I 1 i GO J, 00 OCO(NTj"f-HrfOcOO ^ I tM 00 CO 00 r^ —I Q ^ I— CO iD C^l r*> incO'>fi?-l C-J C^tDCN^-—' C^X^Mt^CM^OCOooG^lcO *. » d » -: 'toafr-; — '^5f°^S'cN55'_: i?5'^X^c=3'»ri^co^c^a^Tr?Jco CTi iT) ,—. -^ ,— CMco,— '—"O^cor^r^.—iinai.—ioi0ioOLnr->oo,—.GM,—..—.—itc.—. O CO o °'^ O QtN o^ o*^ 0°*^ o'^ OCvi o""" O'^ o^ o*^ 0*=*^ O"^ Q " " ". I I I I 1 \ r r .: :: :: , C^ CO ^ r- °^ ,i J, J, ;^ ;; i ;; i ;; ^ ^ S§ 5? OcOOtJ-OC^OtJ^O ^ O ^ O CO o ^ O CO O Tf" O O CO oj rr o ^ o -^ o CO — s s r* .— ^ rrroo 296 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 tests are that experimental errors be RESULTS AND DISCUSSION independently and normally distributed and that variance be homogeneous (data HOMOGENEITY IN THE are homoscedastic). These assumptions WATER COLUMN are generally invalid for water quality Lake Sangchris is a reasonably measurements, but the regular shallow impoundment: in the main heterogeneity of variance displayed by channel of the cold-water arm the lake is these data may be approximately 7-10 m deep; in the vicinity of the dam it normalized by transformation. is approximately 15 m deep; the Model I linear regressions for three of warmwater arm, however, is generally the most influential variables (water more shallow, ranging from 5 to 8 m in temperature, dissolved oxygen, and depth. The overall shallowness turbidity) were performed on pooled data throughout most of the lake combined from stations 1 (0 and 5 m), 3 (0, 5, and with the velocity created by the flow of M) m), 5 (0 m), and 7 (0 and 5 m). In the water through the power plant keep the resulting equations, the relationship lake water well mixed. With the between the two variables in each exception of those measured at Station 3, equation is only a functional one. not 5 or fewer of 24 physical and chemical actually a cause-and-effect one. variables analyzed demonstrated any Each of the equations in Table 9 significant differences (0.05 level) as represents the best fit of Y on X. For each depth varied (Table 3). pair of variables, the linear regression Dissolved oxygen, both as and four forms of curvilinear regression concentration and percentage of (Y = a + fe log X; Y = a + b antilog X; saturation, exhibited significant Y = a + 6 X^ and log Y = a + 6 log differences with depth at all stations X) were calculated. Tests of significance except Station 5, the point of discharge were performed on each of these from the power plant. Concentrations at curvilinear regressions. The five corresponding depths among stations equations were compared to determine were remarkably similar. Even though which function of X best accounted for the lake water was well mixed, the photic the variation in Y. Equations in Table 9 zone was generally less than 2 m deep. are significant at the 0.001 level. Consequently, the concentration of Lake Sangchris and Kincaid Generating Station in 1979. after the construction of a new stack. Aug. 1981 Brigham: Water Quality 297 Table 3. — Relationships among 3-year mean concentrations of physical and chemical variables at several depths at stations in Lake Sangchris. Any two or more means underscored by the same line are not significantly different by the modified new Duncan multiple-range test (0.05 level). Station 1 Variable^ n m 2 m 5 m 7 m Dissolved oxygen 151 10.1 8.3 7.2 6.8 Dissolved oxygen (percent of saturation) 151 97.8 83.1 70.2 66.0 Total phosphorus (as P) 158 0.172 0.187 0.195 0.258 Turbidity (JTU) 158 21 21 26 32 Total iron 158 0.63 0.73 0.82 1.27 Station 2 m 2 m 6 m Dissolved oxygen 144 9.9 9.2 8.1 Dissolved oxygen (percent of saturation) 144 96.0 91.2 77.6 Hydrogen ion concentration (pH) 150 8.05 Total phosphorus (as P) 150 Total iron 150 298 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 dissolved oxygen decreased with depth as -5 m and 10 m - 12 m. While dissolved oxygen was consumed in decomposition oxygen, both as concentration and processes and respiration without percentage of saturation, was corresponding oxygen production. It has significantly higher at the surface, con- been estimated that as much as 50-90 centrations, although decreasing with percent of the available dissolved oxygen depth, were still interrelated. As per- may be taken up by sediments as a result centage of saturation, however, the surface of chemical and bacteriological and 5-m depths were sigruficandy different decomposition activities (Golterman from the lO-m-12-m layer. 1975). 3YEAR CHANGES IN LAKE phosphorus and total iron Total LIMNOLOGY demonstrated significant differences with depth at stations 1,2, and 3 and 1, 2, 3, As there were obvious climatological and 4, respectively. In general, the top differences among study years (Larimore layer of water was significantly distinct & Tranquilli 1981). water quality data from the deepest depth sampled. Since from selected stations were analyzed by the main channel is more narrow and study year to determine if any variables deep in the cold-water arm than it is the appeared to be dependent upon warmwater arm of the lake (a function of climatological cycles or if the concentra- the basin morphology), sediment tions of any variables functioned particles settled to these deep sites but did independently of variations in overall not settle out completely because of the temperature regime or precipitation. Of water velocity. Concentrations of total 24 variables examined (those summarized phosphorus and total iron paralleled the in Table 2), 15 demonstrated some distribution of suspended solids, as significant differences among study years reflected by turbidity values. (Table 4). Station 3, the broadest and deepest Some of the variables exhibiting portion of Lake Sangchris, exhibited differences among years were observed at significant differences for 1 1 variables only a single station. These included with depth. Most were those which one dissolved oxygen (percentage of would expect to exhibit such differences saturation), total phosphorus, sulfate, because of their relationships to vertical particulate organic carbon, and dissolved gradients of dissolved oxygen or to the organic carbon. As no trend was differential settling of sediment particles: apparent from the pattern of occurrence turbidity, total phosphorus, ammonia, among stations, these differences very organic nitrogen, total iron, free carbon likely resulted from changes occurring at dioxide, and total alkalinity, in addition limited areas in the lake and did not have to dissolved oxygen. Both dissolved an apparent overall impact which could oxygen and hydrogen ion concentration be attributed to any climatological (^H) decreased with depth, while differences among years. concentrations of the remaining variables Variables which varied significantly increased with depth. among years at two or more of the stations analyzed, however, were At Station 3, the upper 10 m were sta- considered to be representative of more tistically homogeneous for free carbon generalized phenomena and could have dioxide, total alkalinity, turbidity, total been related to the observed variations in phosphorus, ammonia, organic nitrogen, climate. and total iron. Of these, all but total alkalinity were significantly different Annual mean concentrations for Year from the 12-m sample. For hydrogen ion 1 were significantly lower than those of concentration (pH) the water column at years 2 and 3 for several variables. Station 3 was divided into two For total alkalinity, turbidity, significantly different layers: the surface molybdate-reactive silica, and total Brigham: Water Quality 299 ™ <= \,^CO O) *^ — 5- o.^^ ^ w ^ a; « «£ 0? "^ >'-9 sz a ^ o '^ OlO (0 C 0) > CO r, _^ 2? § CO 73 CO C ^ (D ,„ C/^ -^ c a> sisS CO E £ m ^ Art. 4 300 Illinois Natural History Survey Bulletin Vol. 32, organic carbon, the annual mean RELATIONSHIPS AMONG concentrations observed for Year 1 were VARIABLES lower than for either Year 2 significantly Eight variables in the Model I one- or three stations. For soluble or 3 at two way analysis of variance exhibited no however. Year 1 was orthophosphate, significant differences among stations than the other 2 study significantly higher and depths. These included total 1973, rainfall was years. In alkalinity, EDTA hardness, total dis- above normal, and approximately 33 cm solved ionizable solids, nitrate, nitrite, above normal for 1974. it was over 13 cm total nitrogen, chloride, and molybdate- would be a diluting effect Overall, there reactive silica (Table 5). With the high. For soluble if lake levels were possible exception of water temperature, however, the opposite orthophosphate, depth and location in the Lake Sangchris runoff rates would could be true. Higher basin rather than any thermal effect soluble orthophos- ultimately increase appeared to influence the concentrations surface phate concentrations in the of variables showing significant runoff. differences among stations. Variables precipitation Lower-than-normal where depth seemed to be the determin- significant impact during 1976 had a ing factor included dissolved oxygen, concentrations in the lake. upon nitrogen both as concentration and expressed as nitrate Mean annual concentrations of percentage of saturation; free carbon Year 3 were and total nitrogen for dioxide; hydrogen ion concentration; for years 1 and 2. significantly lower than turbidity; total phosphorus; total iron; study Although field portions of the and forms of organic carbon. Con- conditions terminated in April, drought centrations of most other variables late spring and experienced through remained at reasonably constant levels increased summer, 1976, would not have throughout the year. substantially. the nitrogen concentrations Forms of nitrogen followed a predict- to water is Since nitrogen transport able annual cycle in Lake Sangchris (Fig. cycle of rainfall, nitrogen bound with the 2 and 3). Total nitrogen remained from non- delivery to Lake Sangchris reasonably constant through autumn, decrease with point sources would increasing in winter during January and precipitation. decreases in total annual February. Nitrate, the principal nitrogen i The annual mean concentrations form throughout the year except in late ! barely observed for total dissolved ionizable summer and autumn, fell to late solids and EDTA hardness were detectable concentrations during November, statistically distinct from one another for September, October, and summer-early the 3 study years. With excess coincident with the late blue-green precipitation for 1973, Year 1 values autumn population peaks of organic would be low as a result of dilution, with algae. During this period nitrogen form Year 2 values closely approximating the nitrogen was the principal was "normal" cycle, and those for Year 3 in Lake Sangchris. This phenomenon representing only two- thirds of a yearly observed in 1973 with populations of Raphidiopsis cycle during a period of below - average Oscillatoria geminata and with precipitation. Annual mean concen- curvata and was repeated in 1974 and trations of ammonia for Year 2 were populations of O. geminata When significantly higher than for years 1 Agmenellum quadrupltcatum. algae had decreased to and 3. Dilution from high water levels populations of winter lows by December, nitrate concen- was a contributing factor in Year 1 , and most the time of year represented by Year 3 trations began to increase at from corresponded to the time of year when stations. Releases of nitrogen populations nitrate predominates in Lake Sangchris. declining phytoplankton Ammonia and organic nitrogen were not entirely responsible for the concentrations increase during late observed winter increases in nitrogen summer. concentrations. Since nitrogen is readily Aug. 1981 Brigham: Water Quality 301 leached from soil by percolation and normal in lakes surrounded by runoff, increases in nitrogen concen- agricultural land. tration during late winter and spring are Nitrogen contributions to Lake 302 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Sangchris from nonpoint sources were Environmental Protection Agency estimated to be 250,975 kg N yr', 99.49 1975a). Romkens, Nelson, & Mannering percent of the total nitrogen load (U.S. (1973) examined the nitrogen and oo n CO Aug. 1981 Brigham : Water Quality 303 Fig. 2. —Concentrations of nitrogen in various forms observed at Station 3 (0 m) in Lake Sangchris. phosphorus composition of surface runoff plant. The authors observed that the as affected by tillage methods. They coulter and chisel systems controlled soil compared five tillage-planting systems: loss (reflected as turbidity or suspended coulter-plant, till-plant, chisel-plant, solids in Lake Sangchris), but runoff disk and coulter-plant, and conventional contained high levels of soluble nitrogen Fig. 3. — Forms of phos- phorus and total nitrogen observed at Station 3 (0 m) in Lake Sangchris. 304 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 and phosphorus from surface-apphed Protection Agency 1975a). The Kincaid fertiUzer. The disk and till systems were Generating Station treatment plant was less effective in controlling soil erosion, estimated to contribute 22 kg P yr"' or 0.6 but concentrations of soluble nitrogen percent of the total phosphorus budget. and phosphorus were lower in runoff. To place these loadings in perspective, Conventional tillage, in which fertilizers direct precipitation was estimated to were plowed under, had the greatest soil contribute 4.8 percent of the total and water losses but low losses of soluble phosphorus budget, 190 kg P yr"'. nitrogen and phosphorus. However, high These known point sources of percentages of all nutrients removed by phosphorus (Tovey and Kincaid runoff were components of the sediments Generating Station) contributed to the from all treatments. higher concentrations observed at They concluded that the differences stations 7 and 5, respectively. However, in the nitrogen and phosphorus turbidity relationships (Table 5) followed concentrations in the runoff sediments the same general pattern as did of the various tillage systems were due phosphorus, suggesting that concentra- primarily to selective soil erosion, i.e., tions of suspended solids are of greater small colloidal particles were removed importance in predicting total preferentially to the larger silt- and sand- phosphorus concentrations at various sized particles. It would appear that points in the lake than is the proximity to nutrient input control in Lake Sangchris the known point sources. from nonpoint agricultural sources would Nonpoint agricultural sources be a double-edged sword: agricultural contributed an estimated 3.915 kg P yr"' methods to control soil erosion would still to Lake Sangchris (U.S. Environmental contribute high concentrations of Protection Agency 1975a, Table 6). This nitrogen and phosphorus, while nutrients was 98.4 percent of the total phosphorus would be controlled by methods which load. Romkens & Nelson (1974), in would not curtail soil erosion. analyzing the phosphorus relationships in Concentrations of total phosphorus runoff from fertilized soils, concluded and total iron, which reflect the amount that the relation of the phosphorus of suspended matter in the water, addition rate to the soluble paralleled turbidity levels in Lake orthophosphate or sediment-extractable Sangchris. Concentrations of total phosphorus level in runoff was phosphorus and soluble orthophosphate approximately linear for the soils they appeared to be quite similar within the tested. Their experimental design cooling loop stations (stations 1 through simulated the conditions commonly 5), but concentrations for Station 7 on occurring in the spring in central Illinois: each corresponding date were frequently bare, wet soil subjected to the highly greater. erosive potential of rainstorms. Migratory waterfowl use Lake Total phosphorus concentrations Sangchris as a rest and feeding area appeared to increase gradually around the during autumn and winter. Sanderson & cooling loop from the intake arm (Station Anderson (1981) estimated that an 1) to the point of discharge (Station 5). average of 2.43 kg N (as Nj) and 1.37 kg Superimposed upon this relationship are P (as P20s) per acre was contributed to the higher concentrations observed at the the lake by these birds while in residence deeper sampling depths and the concen- (October through March). Expressed as a trations observed at Station 7, which concentration, 0.13 mg N liter"' and 0.03 receives the Tovey municipal waste water mg P liter"' could be contributed to the (Table 2). The contribution of lake by waterfowl. phosphorus from this effluent was estimated to be 35 kg P yr'' or 0.9 fjercent Waterfowl are more abundant on the of the total phosphorus load to Lake slag pond than on any other part of the Sangchris (U.S. Environmental lake. Excluding the nitrogen and Aug. 1981 Brigham: Water Quality 305 phosphorus contributions added to the dissolved oxygen were generally slag pond, the concentrations derived temporary and of short duration. from waterfowl in the rest of Lake To illustrate this point, dissolved Sangchris could be 0.08 mg N liter"' and oxygen isopleths were drawn, using 0.02 mgP liter'. dissolved oxygen profile data from The impact of contributions of Station 3, the deepest portion of the lake phosphorus and nitrogen from migratory and the site where chemical stratification waterfowl is difficult to isolate because would be most likely to occur. These the contributions occur when inputs are isopleths are shown in Fig. 4. highest from fertilizer leaching and Dissolved oxygen concentrations were surface runoff (Fig. 3). The concen- occasionally below 5 mg liter"' (for con- trations of 0.08 mg N and 0.02 mg P venience, a heavier line in Fig. 4) from. liter'' would not be noticeable at that 1973 through 1975. These were generally time of year. However, these contri- of short duration, and concentrations butions from migratory waterfowl would below 3 mg liter' were rare. In May add approximately 5,425 kg N yr"' and 1976, however, the combined effects of 1,320 kg P yr"' to the lake. the power plant's being shut down and Using the loading and accumulation drought conditions appeared to have an data presented in Table 6, waterfowl effect upon the dissolved oxygen profiles. contributions represent a 95.2-percent Lake Sangchris dissolved oxygen increase in P loading (to 2,707 kg yr"') stratified at Station 3 in May 1976 and and a 4.4-percent increase in N loading remained stratified through August 1976. (to 128,500 kgyr"'). While this stratification had been As discussed above, except at Station observed to some extent in previous years, 5 (the discharge point), dissolved oxygen low concentrations did not appear as values, both as concentration and early nor persist uninterrupted for so percentage of saturation, were long. significantly different with depth at all It would appear that as long as the stations. These vertical gradients in power plant is in operation, or at least Table 6. —Annual total phosphorus and nitrogen loading to Lake Sangchris calculated for an average year (summarized from U.S. Environmental Protection Agency 1975a). Phosphorus Nitrogen . 306 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 mechanically pumping and circulating in a substantial portion of the water mass " the lake water, there will be vertical was below 5 mg liter ' gradients in dissolved oxygen, especially WATER TEMPERATURE in the deeper portions of the lake, but that those will be of short duration. Data The dispersion and elimination of for 1974 illustrate this point (Fig. 4). waste heat from the Kincaid Generating Concentrations changed rapidly and Station and the effect of plant operation frequently. There were no long periods upon the annual water temperature when the dissolved oxygen concentration regime is of particular interest in Lake (LU) Hid3a Aug. 1981 Brigham: Water Quality 307 C Oo (UJ) Hld3a 308 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Sangchris. One unusual aspect of power illustrated in Table 7. Only Station 4 plant operation has been the general lack demonstrated any significant of thermal stratification in the lake temperature differences with depth. At during winter and summer. While all other sites sampled no significant dif- vertical temperature gradients often ferences were observed with depth for the occur, they are of short duration and do 3-year period. not correspond to true thermal Inverse stratification occurred at stratification. Station 7 in the control arm during the Thermal stratification is a period of ice cover. At most stations in phenomenon which implies stability Lake Sangchris, however, thermal while the lake is stratified, generally in stratification through winter was absent, summer and winter in Illinois. The and only temporary gradients were thermocline, a region or layer where the apparent. temperature change is extremely rapid, Fig. 5 graphically illustrates surface prevents complete vertical mixing and water temperature relationships among separates the water column into two sampling stations in the cooling loop of distinct layers: an epilimnion, which Lake Sangchris from the source of the circulates throughout the ice-free period, heated water (Station 5) to the plant and a hypolimnion, a cool bottom layer intake (Station 1) from September 1973 that can gradually become anoxic in through September 1976. One hundred eutrophic lakes. forty sets of water temperature profiles An important consideration in were taken during this period and were determining whether thermal included in the figure. Stations are stratification can occur is the ratio located vertically on the figure between the depth of the water which can proportional to their distances from one be mixed by the wind and the total another. Lines shown represent increases depth. The depth of wind mixing is above the intake (ambient) water temper- determined by surface area and the ature (°C). amount of exposure to wind (Golterman Several aspects of the water 1975). Once thermal stratification has temperature regime are readily apparent become established, the stability is so from the figure. First, increases in water great that no storm can disrupt it. This temperature were of greater magnitude stability is the result of the density during the first year (September 1973 differences between the warm surface through August 1974) than in subsequent water and the cool subsurface water. years. During September, January The vertical homogeneity of water through April, and June through August temperature in Lake Sangchris is of the first year, there were considerable Table 7 —Relationships among 3-year mean water temperatures (°C). illustrating significant dif- ferences witfi depth. Any two or more means underscored by the same line are not significantly dif- ferent (0.05 level). Station n Om Im 2m 3m4m 5 m 6 m 7m 8m 9m 10mllml2m 1 1.052 16.3 16.3 16.2 16.2 16.3 16,1 15.9 15.6 8,9 2 1.219 16.7 3 1,683 A 1.308 4 924 Aug. 1981 Brigham: Water Quality 309 areas of the lake (to Station 4, Fig. 5) were 10°C or more above the intake where observed water temperatures were water temperature. Increases of from 7° greater than or equal to 9°C above intake to 9°C above the intake water water temperatures. Furthermore, there temperature were common. were intervals when water temperatures As a result of scheduled maintenance during September 1973 and January and downtime, power plant operation through April 1974 exceeded 1 1 °C above was an on-off, off-on phenomenon intake water temperature. By compari- during May, June, and portions of son, throughout the remaining 2 years of September, October, and November study, there were only three occasions 1975 and roughly from February 1976 when discharge temperatures at Station 5 through the end of the study period sl- o E ra O 310 Illinois Natural History Slrvev Bili etin Vol. 32. Art. 4 (Larimore & Tranquilli 1981: Fig. 2). Al- much of the 1976 spring, rapid changes though the plant was in operation during in the isopleths reflect that this was not the to cn oo mI SNOIIVIS . Aug. 1981 Brigham: Water Quauty 311 result of continuous operation as had oc- SLOPE curred during the comparable time period in 1974. Finally, in late July 1976 heat additions to Lake Sangchris were stopped for the remainder of the summer. Since May 1975 then, the thermal patterns in Lake Sangchris have been disrupted as a result of the off-on nature of plant operation, as illustrated by the 1°C line. The 1 °C line (separating the areas greater than from those less than 1 °C above intake water temperature) moves from Station 5 in November 1975 to Station 2 by late November 1975 and back to Station 5 by late Feburary 1976. It bounces back and forth around the entire cooling loop, reflecting the interrupted nature of plant operation. Data interpretation during this period for any thermal effect would be very difficult. Linear regressions with 0.001 -level confidence intervals were calculated for the mean water temperature at each station (Y) against the mean intake water temperature (X) for the period September 1973 through August 1976 to determine whether there was any predictive value in the data. Could the water temperature at the plant intake be related to ambient water temperature? Table 8 summarizes the equations derived from the linear regressions of mean water temperatures from stations 2 through 7 on that at Station 1. Fig. 6 illustrates the slopes and intercepts of the lines derived for the cooling- loop stations. Proceeding around the cooling loop from plant intake to plant discharge, the observed water temperatures become less dependent upon intake or "ambient" Table 8. — Equations derived from linear regressions of mean water temperatures (°C) at stations 2 through 7 on the mean water temperature at Station 1 Stations Sept. 1973-AuK. 1976 1&2 Y = 1&3 l&A 1&4 l&B 1&5 1&7 . , 312 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 compiled over 3 years, including that Equations were developed for all 24 period when power plant operation was variables included in the data set. Based disrupted, as has been described. The upon the 32-month data set for stations 1 isopleths in Fig. 5 indicate the areas or 2, 4, and 7 (0 and 5 m). Station 5 (0 and 2 distances that were required to cool water m), and Station 3 (0, 5, and 10 m), con- to the various temperatures above the centrations of the 24 variables could be intake (ambient) water temperature at predicted from hardness (13). water any specific time period. While the area temperature (5), nitrate (3), total alkalin- required for cooling at any one time is ity (1), total dissolved ionizable solids (1). dependent upon power plant operating and turbidity (1), for example. Other conditions and climatic conditions, in combinations could be developed, general most of the added heat is dissipat- however. As it is, most variables could be ed at least by the time the water mass has predicted from several equations. Any of arrived near the vicinity of stations A or six variables could be used to predict total 3. phosphorus concentrations, for example. That only 50-60 percent of the cool- The type of functional relationships ing loop circuit might actually be needed developed varied importantly among the for heat dissipation is further illustrated variables used to develop the equations. by the relationships existing among the The equations developed using water 3-year mean concentrations for water temperature and dissolved oxygen as con- temperature presented in Table 5. centration were virtually all logarithmic, Station 4 appears to be the location which while the equations using dissolved is an interg^ade area. It is not distinct oxygen (percentage of saturation), total from the discharge point (Station 5), but alkalinity, total dissolved ionizable solids, the water has cooled somewhat so that EDTA hardness, and turbidity were all Station 4 is not entirely distinct statistical- linear. Virtually all equations developed ly from Station 3. using free carbon dioxide and hydrogen ion concentration (pH) were exponential. FUNCTIONAL RELATIONSHIPS Equations were developed using the AMONG WATER QUALITY pooled data from the six stations VARIABLES identified above, and a calculated Each of the equations in Table 9 concentration would represent a likely represents the best fit of Y on X for water concentration to be expected at any point temperature, dissolved oxygen (both as in the lake. In more specific circum- concentration and percentage of stances, equations could be developed for saturation), free carbon dioxide, hydro- individual sites in Lake Sangchris or gen ion concentration (pH), total seasons to identify the probable outcome alkalinity, total dissolved ionizable solids, of various management strategies, such as EDTA hardness, turbidity, and nitrate. the impact of raising or lowering lake These variables were selected to represent water temperature upon dissolved commonly performed field and labora- oxygen. Even though the equations tory procedures and to include the developed are functional, not cause-and- important variables in the lake. Each of effect, relationships, the difference which these equations is significant at the 0.001 might occur as a result of such a change level could be predicted. EDTA hardness and nitrate each The value of this procedure is that a could be used to predict the concentra- particular variable can be calculated tions of 13 other variables; total from a number of other variables. For ex- alkalinity, 1 1 ; and total dissolved ionizable ample, water temperature could be solids, 10. The remaining variables could calculated from dissolved oxygen, free be used to predict the concentrations of carbon dioxide, hydrogen ion concentra- seven or fewer variables. tion (pH), or EDTA hardness. Aug. 1981 Brigham: Water Quality 313 314 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 9. —Continued. EDTA Hardness Aug. 1981 Brigham: Water Quality 315 Table 10. —The position of Lake Sangchris compared with 30 Illinois lakes for selected variables sampled in 1 973 by the National Eutrophication Survey. Lakes are ranked by the eutrophication index, with the most eutrophic at the top (modified from U.S. Environmental Protection Agency 1975a). 316 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 For comparison, Lake Springfield, used phosphorus accumulation of 7,430 kg for cooling by the city-owned Lakeside and a net nitrogen accumulation of Power Plant, has a net annual 376,595 kg (U.S. Environmental CO o c mCO 3 CO oa. >. Aug. 1981 Brigham: Water Quality 317 Table 12. —The percent of Illinois lakes sampled by the National Eutrophication Survey with higher concentrations or values than those of Lake Sangchris. followed by the number of lakes with higher concentrations or values (in parentheses). Lakes are ranked by eutrophication index, with the most eutrophic at the top (modified from U.S. Environmental Protection Agency 1975a). 318 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Nitrogen contributions to the lake higher median inorganic nitrogen, 20 from nonpoint sources were estimated to had greater mean Secchi disk trans- be approximately 250,000 kg N yr' or parencies, 17 had greater mean nearly 99.5 percent of the total nitrogen chlorophyll a concentrations, and only 8 load. had lower dissolved oxygen concentra- Nonpoint agricultural sources contri- tions. Data were collected during 1973. buted an estimated 3,915 kg P yr"' or Despite the high total phosphorus nearly 98.5 percent of the total loading to the lake (nearly 4,000 kg P phosphorus load. Point source contribu- yr"'), the National Eutrophication Survey tions to the lake were minimal, represent- concluded that Lake Sangchris was ed chiefly by the Tovey and Kincaid phosphorus limited. While there is Generating Station treatment plants. considerable phosphorus in the lake, it Nutrient input control in Lake does not appear to be abundant in a form Sangchris from nonpoint agricultural that can be used directly by algae. sources would be difficult; agricultural Increases in water temperature (above methods to control soil erosion would the ambient or intake water temperature) still contribute high concentrations of were of greater magnitude during the nitrogen and phosphorus, while nutrients first study year (September 1973 through could be controlled by methods which August 1974) than in subsequent years. would not curtail soil erosion. Scheduled maintenance and downtime With the possible exception of water contributed to the on-off, off-on nature temperature, depth and location in the of heat additions to the lake during the Lake Sangchris basin rather than any last 2 study years. thermal effect appeared to influence the During the first year of study, there concentrations of variables that showed were considerable areas of the lake where significant differences among stations. observed water temperatures were greater As long as the power plant is in than or equal to 9°C above intake water operation, or at least mechanically temperatures. Furthermore, there were pumping and circulating the lake water, intervals when water temperatures during there will be vertical gradients in September 1973 and January through dissolved oxygen, especially in the deeper March 1974 exceeded 11°C above intake portions of the lake, but these will be of water temperature. In comparison, short duration. throughout the remaining 2 years of Of 31 lakes investigated by the U.S. study, there were only three occasions Environmental Protection Agency when discharge water temperatures were National Eutrophication Survey, 26 lakes 10°C or more above the intake water had higher median total phosphorus than temperature. Increases of from 7° to 9°C Lake Sangchris had, 29 had higher above intake water temperature were median dissolved orthophosphate, 9 had common. Aug. 1981 Brigham: Water Quality 319 REFERENCES CITED fertilized soils. Journal of Environmental Quality 3(1):10-13. Public Health Association, American . . American and J. V. Mannerinc. 1973. Water Works Association, and Water Pollu- Nitrogen and phosphorus composition of tion Control Federation. 1971. Standard surface runoff as affected by tillage method. methods for the examination of water and Journal of Environmental Quality 2(2):292-295. Health Anderson. 1981. wastewater. 1 3th ed. American Pubhc Sanderson, G. C and W. L. Association. Washington. D.C. 874 p. Waterfowl studies at Lake Sangchris, 1973-1977. Pages 655-690 in R. W. Larimore Golterman. H. L. 1975. Physiological limnology. and A. Tranquilli, eds.. The Lake Sangchris Elsevier Scientific Publishing Company, New J. study: case history of an Illinois cooling lake. York. 489 p. Illinois Natural History Survey Bulletin 32(4). Kramer. C. Y. 1956. Extension of multiple range U.S. Environmental Protection Agency. 1976a. tests to group means with unequal numbers of Report on Sangchris Lake Christian County replications. Biometrics 12:307-310. Illinois EPA Region V. U.S. Environmental Larimore, R. W., andJ.A. Tranquilli. 1981. The Protection Agency Working Paper No. 314. Lake Sangchris project. Pages 279-289 in R. W. Corvallis Environmental Research Laboratory, Tranquilli, eds., The Lake Larimore and J. A. Corvallis. n. p. Sangchris study; case history of an Illinois 19756. Report on Lake Springfield cooling lake. Illinois Natural History Survey Sangamon County Illinois EPA Region V. U.S. Bulletin 32(4). Environmental Protection Agency Working Nelson. 1974. Paper No. 317. Corvallis Environmental RoMKENS, M. J. M,, and D. W. Phosphorus relationships in runoff from Research Laboratory, Corvallis. n. p. Phytoplankton Dynamics in a Cooling Water Reservoir Robert L. Moran ABSTRACT been designated the discharge arm and contains stations 4, B, and 5. The western Lake Sangchris is an 876-ha reservoir arm, which supplies the cooling- water built between 1963 and 1966 as a cooling- intake, is referred to as the intake arm water supply for a 1,232-megawatt coal- and contains stations 1 and 2. Together, fired electric generating station. The con- these two arms and the main body of the stant circulation of water around the lake, with stations A and 3, form the cooling loop of the lake prevented perma- cooling loop. Complete circulation of the nent stratification and maintained a high water mass can be accomplished within degree of spatial homogeneity in the 1 1 days if all circulating water pumps are phytoplankton. Condenser passage did operating. The third, eastern, arm is not not produce any differences among the directly involved in the cooling loop flow; phytoplankton communities in the intake it has been named the control arm and and discharge canals although primary contains Station 7. productivity was temporarily depressed when temperatures exceeded 30 °C. The The purpose of this study was to control arm had significantly higher document the composition and dynamics productivity rates than the other two of the phytoplankton in this reservoir and arms had and usually had the highest to determine what effects the operation of concentrations of phytoplankters, the Kincaid Generating Station and its probably a result of the higher thermal discharge had upon this phosphorus concentrations in that area community. resulting from the effluent from the Tovey sewage treatment plant. A cluster METHODS analysis of the phytoplankton in the cooling loop, control arm, and five bays SAMPLE COLLECTION AND indicated that the entire lake was well PREPARATION mixed and quite homogeneous in the phytoplankters that it contained. Samples of the phytoplankton were collected at stations 1, 2, 3, 4, 5, and 7 INTRODUCTION during the first 2 years and at stations 2, Lake Sangchris is an 876-ha reservoir 4, and 7 during the third year. Samples built between 1963 and 1966 as a cooling- were obtained with a 4.2-liter Kemmerer- water supply for Commonwealth Edison's style polyvinyl chloride (PVC) bottle and 1,232-megawatt coal-fired Kincaid were returned to the lab in 1 -gallon Generating Station. The lake is composed (3.785-liter) plastic bottles and kept of three arms with a general north-south under refrigeration overnight. Samples orientation (Fig. 1). The electric for microscopic examination during the generating station lies between the first year of study were concentrated by western and middle arms and is settling 1 -liter samples in 1 -percent connected to them by canals. The middle Lugol's solution for a minimum of 5 arm, receiving the thermal effluent, has days. The supernatant was siphoned off with a J-shaped tube until 50-80 ml L. Moran is Director. Division of .^ir Robert remained with the sediments. The Pollution Control, Vigo County Health Department, Terre Haute. Indiana. sediments were further concentrated by This chapter subtnitted in Dec. 1978. centrifugation, and then the volumes 320 Aug. 1981 Moran: Phytoplankton 321 H LAKE SAN6CHRIS i) I I I I / / Fig. 1. — Lake Sangchris, a cooling lake in central Illinois, and its sampling stations. were adjusted to an appropriate amount. deep, covered by a no. 1 cover slip. During the second and third years, Counting and identification of the algae samples were concentrated by means of a were accomplished with a Zeiss Foerst centrifuge. microscope using both bright field light and Nomarski differential interference EXAMINING, COUNTING, AND contrast. All large phytoplankters that IDENTIFYING SAMPLES lay within two transects of the counting Samples were examined with a circu- chamber under 160 X magnification were lar plankton counting chanjber 0.6 mm counted. Under 400 X magnification, all 322 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 nanoplankton that lay within 20 visual dark bottle experiments were performed, fields was counted. If the count of the utilizing these two methods as well as the most common taxon did not total 100 ' calculated from the mean dimensions through 1 cm' of the refer- gfiven in the taxonomic literature or as ence plane given by Nauwerck (1963) and Evans & s' = the gradient (calories/cm) Stockner 10' is equal to I \A. (1972); m' across the reference plane PHOTOSYNTHETIC RATES A = the coefficient of eddy diffusion, cm'/sec Photosynthetic rates were determined under natural conditions by using the Eddy diffusion was determined at 1-m ApH-CO, method (Verduin 1956) and intervals through the entire vertical water the '^Oj method (Ryther 1956). Light- column. Aug. 1981 Moran: Phytoplankton 323 SPECIES DIVERSITY Table 1. — Mean light compensation point (Do.oi) in meters at four stations in Lake Species diversity (H) was determined Sangchris, Ttie numbers of samples are in by using the Shannon-Wiener Index parentheses. (Shannon & Weaver 1949). as Discharge- and IVIain-Body and recommended by Pielou (1975). The Control -Arm Intalie-Arm Stations IVIcan Stations form of the expression used v^as: In pi H'= -Ipi 1.85 2.16 2.41 2.42 3.09 Where (36) (18) (7) pi = the proportion of the ith species to the total number of water chemistry data (Brigham 1981) individuals in the community which showed this station to have the An increase in the number of taxa or in highest 3-year mean turbidity level. the evenness of distribution of individuals among taxa will result in an increase in EDDY DIFFUSIVITY the index value. The evenness of the species Measurements of eddy-diffusion the distributions (J) was also analyzed by coefficients (A) (Fig. 2) showed that ratio of the species diversity indices (H') within the upper 3 m the mean rates to the maximum value possible for a ranged from 1.65 to 9.01 cm2/sec. community of the same size, such that: Station 4 had the highest mean rates, while those of stations 2 and 7 were J = H'/lnS Where similar. Below 3 m Station 2 had the Station the S = the total community size highest mean rates and 7 This expression removes the effects of lowest. Eddy diffusion coefficients of 0.02 - are typical of a sample size upon the index value (Pielou 0.15 cm2/sec (Csanady 1964 and Sweers 1975). thermocline Relationships among parameters were 1970). In Lake Sangchris the lowest mean determined through the use of the rate was 0.25 cm^/sec, indicating that Student-Newman-Keuls multiple- stable stratification of the water column not develop. constant circulation range test (Zar 1974) modified to accept did The uneven group sizes. Significance was determined at the 0.05 level, and where - S TAT 1 N 2 "significance" is claimed, P = 0.05 level -• STATION 4 -# STATION 7 unless another level is indicated. Unless otherwise stated, the physical-chemical data are from Brigham (1981). RESULTS AND DISCUSSION PHOTIC ZONE As a routine part of primary productivity measurements, the light compensation point was determined at those stations where current velocity did not preclude use of the submarine photometer. In all, 36 measurements A (cm /sec) were made at stations 2, 3, 4, and 7 Fig. 2 Eddy diffusion coefficients in the of the photic — I lable 1). The mean depth vertical water column at three stations in Lake 2.41 with Station 2 being zone was m, Sangchris. Each point is the mean of seven to somewhat more clear. The shallow photic nine measurements taken during the spring, zone at Station 7 was confirmed by the summer, and autumn of 1974, 1975. and 1976. 324 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 of water by the power plant was, In January-February 1975, Synedra undoubtedly, the most important factor tenera bloomed with concentrations as in preventing seasonal stratification from high as 16,800 units/ml. This pulse was developing. of a magnitude similar to that of the previous Melosira pulse. The mean SEASONAL PERIODICITY biovolume, however, was slightly higher, In Lake Sangchris the seasonal 1.4 yl/1, than in the Melosira bloom in abundance of phytoplankton generally April 1974. followed a bimodal pattern, with late In the January-April 1976 period, a winter or spring pulses of diatoms and a pulse of a minute centric diatom, late summer pulse of blue-green algae Cyclotella pseudostelligera, occurred (Fig. 3 and 4 and Table 2). The periods with concentrations at times as high as separating these pulses were composed of 36,000 units/ml, accounting for as much mixed communities of green algae, as 75 percent of the total phytoplankton diatoms, and sometimes blue-greens. The community. This species, in addition to bimodal pattern of phytoplankton being quite small, had very lightly periodicity is typical of lakes experiencing silicified frustules. The mean biovolume nutrient depletion during the summer during this period was about 1.4 ^1/1. (Fogg 1975). In the late summer of each year the The first diatom pulse in this study blue-green algae produced pulses with occurred in April 1974 when Melosira mean concentrations as high as 82,000 distans v. alpigena and M. italica units/ ml. Even though the average unit achieved concentrations of 5,000-7,000 size was less than that of the other major units/ml and constituted about 50-60 groups, these blooms usually produced percent of the phytoplankton the seasonal biomass maximum. community. M. distans v. alpigena At the beginning of this study, declined more rapidly, so that by the end October 1973, a blue-green bloom was of April, M. italica was the principal in decline, and the principal component species. The mean biovolume during this at that time was Oscillatoria geminata. period was 1.1 m1/1. The average density was about 6,000 LAKE SANGCHRIS MEAN PHYTOPLANKTON MEAN DISCHARGE WATER TEMPERATURE Ulc Ul sa. 111 (9 < Z < Z I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I sondIjfmamj jasondIjfmamjjas ondIj f M A M J J A S 19 76 Fig. 3. —Mean numbers of phytoplankters (units/ml) and mean temperatures in the discharge arm in Lake Sangchris, 9 October 1973—9 September 1976, Aug. 1981 Moran: Phytoplankton 325 units/ml, and the mean biovolume was primarily of O. geminata and about 1.2 m1/1. The following year, Raphidiopsis curvata, 70 and 20 percent, August-October 1974, the pulse (22,804 respectively, with the biovolume being units/ml) was initially composed 2.9 k1/1. In September-October the r^ 00 C30 Tf en CM CTi 326 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 mean density increased to 43,634 respectively, and the biovolume increased units/ml. The dominant species changed to 3.6 (i.1/1. to Agmenellum quadruplicatum and O. In August-October 1975, the pulse geminata, 42 and 37 percent, began with O. geminata, R. curvata, and 3 O 3^ u n * Aug. 1981 Moran: Phytoplankton 327 A. quadruplicatum, 50, 29, and 2.5 A. quadruplicatum became the most percent, respectively. The mean density common species in September, during August was 55,372 units/ml, and accounting for about 82 percent of the the mean biovolume was 5.8 /4I/I. Again phytoplankton community and for about ^co^^ o^onr^o^tooi eoinr»^ t^ w r^ I csi csi .— .60 .he K (- 3 «> n! .u eS-a -S 3 : .a c . 1 s ~ p o ^ Sol I.I a : > ^ ':5.2 c OJ o « a "(5 - s .? s Q Z e Si B B O li g u 3 3 3 £-2 1 a C s a, r 328 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 E S Q. o > T3 C o oa E o o 0) o OQ. I III I I I I—— ,oi»(i'"/«iiun) Aug. 1981 Moran: Phytoplankton 329 CHRYSOPHYTA 1;;;^;^ CHLOROPHYTA ^| CYANOPHYTA [ | EUGLENOPHYTA ( | PYRROPHYTA f ] CRYPTOPHYTA ^H r^ai 4 SEP 9 OCT 6 NOV 17 DEC 16 JAN J3 FEB 12 MAfi IT APR 14 MAY 17 JUN 15 JUL Fig. 4. —Continued. CHRYSOPHYTA WM CHLOROPHYTA PB| CYANOPHYTA [ | eUGLENOPHYTA [__ J CRYPTOPHYTA ^H I P l| Qi B SEP 16 OCT II NOV 22 DEC 13 JAN 10 FEB 16 MAR 13 APR 26 MAY B JUN 2T JUL 12 AUO 24 AUG 9 SEP 1975 ' 1976 Fig. 4. —Continued. 68 percent in October. However, the in late July when R. curvata accounted mean density declined to 30,786 units/ml, for about 38 percent and Anacystis and the mean biovolume declined to 0.9 incerta about 10 percent of the jj1/1. community of about 25.000 units/ml. By In 1976 the blue-green pulse began 12 August the cooling loop mean had 330 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 dropped to about 14,500 units/ml with The Euglenophyta, Cryptophyta, and the major species being R. curvata, 32 Pyrrophyta were never important in Lake percent; O. geminata, 13 percent; Nitzs- Sangchris. They were generally more chia acicularis, 5 percent; and Synedra common during the warmer months, but tenera, 5 percent. In the control arm the entire assemblage only once the pulse had continued to increase to a accounted for as much as 8 percent of the mean concentration of almost 54,000 total community. units/ml with O. geminata and R. curvata accounting for 66 and 8 percent, STATION COMPARISONS respectively, of the total. The mean The annual mean total biovolume for this period was 3.1 -yA/l. phytoplankters at each station fell into By 24 August the cooling loop the range of 8,415.4 units/ml at Station 3 phytoplankton had dropped to about to 12,995.1 units/ml at Station 7 (Table 7,000 units/ml and the control arm 3). Phytoplankters at Station 7 (control phytoplankton to 7,800 units/ml, with arm) were significantly more abundant the blue-greens still dominant. The mean than at the cooling-loop stations, and biovolume was about 0.9m1/1- On 9 within the cooling loop, the population at September the cooling loop mean had Station 2 (intake arm) was significantly increased to about 10,000 units/ml, and greater than at the other stations. At in the control arm the mean had Station 3 the phytoplankton population increased to 16,000 units/ml. The was significantly lower, an artifact dominants were A. quadruplicatum, 25 introduced by the lower populations in percent; O. geminata, 11 percent; andi?. the 10-m samples. The higher concentra- curvata, 16 percent of the total. The tions in the control arm were probably phytoplankton communities at all due to the significantly higher total stations were similar in composition. By phosphorus concentrations there, rather mid-September the phytoplankton had than to increased mortality within the returned to concentrations typical of the cooling loop. season, about 40,000-50,000 units/ml The vmiter months, December through (Coutant 1977). February, were usually marked by a The g^een algae were most common diatom pulse and concentrations of about in periods between the pulses of the half the annual mean. While an analysis diatoms and blue-green algae. The of variance indicated significant communities in which this group formed differences among the stations, the a significant part were always small, Student-Newman-Keuls test was unable usually 2,000 units/ml or less, and to detect them. The analysis did suggest usually less than 1.0 m1/1 in biovolume. that the populations at stations 5 and 7 During November 1973-March were significantly lower than the others. 1974, Monoraphidium contortum and In the spring months. March through Selenastrum westii composed 34 and 8 May, the phytoplankton was dominated percent, respectively, of the by diatoms and green algae. The phytoplankton community, which was 90 population at Station 7 was significantly percent chlorophycean and had a mean highest, while within the cooling loop, biovolume of 0.2 jj1/1. populations at stations 2 and 4 were In March 1975 M. contortum was the significantly higher than those at stations dominant species with about 61 percent 1,3, and 5. This result was an artifact of of the total community (biovolume 0.1 a third-year diatom pulse which was h1/1). and in November 1975 M. numerically quite large, but was only contortum made up about 34 percent of sampled at stations 2, 4, and 7. the total. Through the spring and In the summer months, June and July, summer of 1976, M. contortum periodically the phytoplankton populations at stations appeared as a common species, and in 2, 4, and 7 were again significantly February was about 22 percent of the higher than those at stations 1, 3, and 5. total. Again, in the third year a large bloom Aug. 1981 Moran: Phytoplankton 331 Table 3— Mean phytoplankton concentrations, units/ml, at stations 1, 2. 3. 4, 5, and 7 in Lake Sangchris. October 1973 through August 1976 Relationships among station phytoplankton concentrations were determined by the Student-Newman-Keuls multiple range test, modified for unequal group sizes. Means underscored by the same line are not significantly different at the 05 level. Annual Concentrations at Stations 1 8,415.4 9.255.2 9,681.1 10,096.9 10,762.3 12,995.1 December-February Concentrations at Stations 5 2 3 1 3,226.4 3,649.6 5.185.6 5,297.0 5,411.5 6,168,6 March- IVlay Concentrations at Stations 1 5 4 3.400.4 3.560.9 3,999.7 6,385.8 6,749.6 10,104,4 June-July Concentrations at Stations 1 4 1,689,7 2.281.2 2,819.0 4.873.0 5,630.6 5,661.0 August-November Concentrations at Stations 3 2 5 1 18,113.4 18,835.3 21,466.5 21.532.8 23.157.4 25.455.5 occurred (the blue-green pulse started in concentration at Station 2 reflects the July 1976, a month earlier than in the 2 large third-year diatom pulse not previous years), and since only stations 2, included at stations 1, 3, and 5 rather 4, and 7 were sampled, their means than any real increase in phytoplankton reflected the increased concentration. concentration. Evidently, condenser When the July 1976 samples were passage, with the accompanying thermal discarded from the analysis, all stations rises experienced during this study, was were similar. not fatal to the phytoplankton. In the late summer and autumn SPECIES DIVERSITY months, August through November, the AND EVENNESS blue-green algae dominated. All of the cooling-loop stations were similar, but The species-diversity index, H , was Station 7 had significantly higher determined for the surface collection at concentrations. If the 12 August 1976 each station and date during this study. Station 7 sample was discarded (that Since all stations were similar, only the period when the cooling-loop populations mean of the cooling-loop stations and of had collapsed, but the control-arm pulse Station 7 were presented (Fig. 5). While continued), all stations were then similar. the index number has no absolute Examination of the data indicated meaning, it is a valuable tool for that on a seasonal or annual basis there comparing collections within a study. the was no consistent significant difference in The evenness index, J, looks only at phytoplankton concentrations between evenness of the distribution of species and the intake canal (Station 1). the discharge is not affected by the sample size, as is canal (Station 5), and the discharge arm H', While the Shannon-Wiener Index (Station 4). Station 3 was significantly usually falls within a range of to about lower, reflecting the effect of the 10-m 4, the evenness component has a range of sample on the station mean. Within the 0-1. In both indexes, the higher the cooling loop, the higher annual mean number, the more even the species 332 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 SPECIES DIVERSITY (H'l EVENNESS COMPONENT (J) • COOLING LOOP B MEANotLAKE .5 0. z o -.4 O m z z 2 S J Fig 5 —Species diversity z and evenness indices of the -.5 z phytoplankton community in * 8 Lake Sangchris. 9 October » 1973-9 September 1976, distribution. The evenness component greens, and blue-greens, and then was calculated from the lakewide mean. dropped again with the winter diatom All 3 years presented the same general pulse. pattern, a species diversity value near 1 The evenness component ranged from during the winter-spring diatom bloom a low of 0.06 in January-February 1975 and a steady increase to a maximum to a high of 0.42 in July of 1974 and 1975. value of around 3 in the early summer, These low values indicate that even when prior to the blue-green bloom. With the the phytoplankton community had blue-green pulse, the diversity index diversity indexes of 3 or more, the dropped rapidly to a value near 1. In distribution of species was not November and December, the diversity exceptionally even. Since the evenness rose toward 2.5, as the phytoplankton index paralleled the diversity index became a mixed community of diatoms. throughout the study, uneven Aug. 1981 Moran: Phytoplankton 333 distribution of species was the common clustering was evident. The lake samples situation. (designated by the prefix L in the station code) generally clustered with the ANALYSIS CLUSTER cooling-loop stations (LOll through A cluster analysis technique using a L151) in groups A, B, and C and the modified Jaccard similarity index was control-arm stations (L161 through applied to an extensive collection taken L204) in groups C, D, and F. The lake on 26 July 1976. The purpose was to test samples taken from the lower depths for any station- or depth-related (designated by the last number of the distribution patterns among the station code) were generally distributed phytoplankton within the main lake and through all of the cluster groups. bays (Fig. 6). The results were presented Thus, while some patterns were in the form of a computer-generated displayed by the analysis, the overall level dendrogram (Fig. 7) which was divided of similarity was quite high. The into six clusters, designated A through F. similarity of the bay and lake samples The most striking feature of the indicated that their waters were in analysis is the high degree of similarity intimate contact with one another. Using among all stations (0.8559 or higher) with a similar cluster analysis on the 97 percent of the comparisons having a zooplankton data, Waite (1977) found similarity index above 0.900. No that the zooplankton clusters were relationship between bay location and separated primarily by season. Within (BOOS BOIO , L07I L075 stations are Fig 6 —Stations sampled for phytoplankton cluster analysis, 26 July 1976. Lake the station marked by an asterisk and the station code prefix L Bay stations are marked by a dot and number, and the third is the code prefix B The first two integers of the station code are the sample depth in meters at which the sample was collected. 334 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 sample dates the bays (littoral areas) and in phytoplankton. However, during the limnetic areas were usually quite similar winter months Station 7 zooplankton MODIFIED JFlCCflflD INDEX .fffl .ISO LAKE SflNGCHRIS PHTTOPLflNKTON CLUSTER flNHLTSlS - 26 JULT 1976 Fig. 7. —Cluster analysis of 64 phytoplankton samples from Lake Sangchris, 26 July 1976. Aug. 1981 Moran: Phytoplankton 335 communities differed from those of the 1976 a blue-green algal pulse had started. coohng loop. The similarity of the When the generating plant shut down, phytoplankton of the control arm to that the mean cooling-loop temperature fell to of the cooling loop also suggested that about 24°C within 2 days. This sudden this area was quite similar to the cooling drop in water temperature below the loop as a habitat for phytoplankton. optimal range for the blue-green algae probably caused the collapse of the blue- WATER TEMPERATURE green population in the cooling loop. In Lake Sangchris the occurrences of In the control arm, however, 2 days the major algal communities were after the shutdown the temperature had correlated with water temperature. dropped only 2.3»C to 26.7"'C, possibly Diatoms were most common from explaining why the pulse continued at autumn through spring when water this station. However, by 24 August the temperatures ranged from 6" to IB^C. control-arm temperature (24.63''C) was The green algae were most abundant in similar to that of the cooling loop spring and summer when water (24.70°C), and the blue-green bloom had temperatures were within the 15°-25°C collapsed. By 9 September 1976 a slight range. The blue-greens bloomed in the increase in the phytoplankton was late summer when water temperatures observed at all stations, and by mid- were above 30"C and declined when September the population was similar to the previous year's at that time (Coutant I temperatures were within the 15°-25°C These temperature ranges generally 1977). agree with the observations of Cairns (1956) and others. NUTRIENTS The interruption of the blue-green In fresh waters, nitrogen and pulse when the generating station shut phosphorus are regarded as the nutrients down on 9 Augfust 1976 (but continued most likely to be limiting to algal growth. pumping water intermittently) was The forms of nitrogen most readily used probably related to the substantial drop by algae are nitrate and ammonia in water temperature experienced (Stewart 1974). In Lake Sangchris the immediately following the shutdown mean concentration of nitrate nitrogen was (Table 4 and Brigham 1981). During July 1 .993 ± 1 .820 mg/1, and that of ammonia and August of 1974 and 1975, the mean nitrogen, 0.105 ±0.155 mg/1. Nitrate discharge-arm temperature was 36.04''C, nitrogen concentrations of less than 0.02 and the mean control-arm surface mg/1 have been reported to be limiting to temperature was 30.46°C. The year 1976 algae (Prowse & Tailing 1958). In Lake was cooler than normal, and the July Sangchris, nitrate nitrogen fell to 0.01 discharge-arm water temperature was mg/1 in the autumn of each year 3. 5 PC cooler than it was in the 2 previous (Brigham 1981). With the exception of years. Similarly, the water of the control 1975, these periods were quite brief and arm was 2.71°C cooler than it was in the 2 the concentration of ammonia was great previous years. However, both stations at enough to raise the readily available i32.50»C and 27.47"C, respectively, were nitrogen to 0.06 mg/1 or more. During ' still near the optimal temperature range these times, the plankton was dominated for the blue-green algae, and by 26 July by nonheterocystous (non-nitrogen- Table 4.—Water temperature variations (°C) in tine discharge and control arms of Lake Sangchris during July and August 1974, 1975, and 1976, derived from Brigham's data (1981). Station 4 Station 7 (Discharge Arm) (Control Arm) 336 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 fixing) blue-green algae. Thus, it is The N-to-P ratio expresses the doubtful if the phytoplankton population relationship of nitrogen and phosphorus was ever limited by nitrogen. concentrations in waters. The ratio in protoplasm is about 8. and this may be is generally regarded as Phosphorus regarded as the optimal ratio for nutrient single important algal nutrient the most media to promote growth (Verduin in temperate waters and the nutrient 1967). A higher ratio indicates limiting. single most most likely to be The insufficient phosphorus to utilize fully the cultural common aspect of available nitrogen; a lower ratio indicates is increase in eutrophication of waters the insufficient nitrogen to utilize fully the phosphorus levels and the resultant available phosphorus. increase in algal biomass. In Lake In Lake Sangchris the N-to-P ratio Sangchris the mean concentration of based upon the mean concentrations of total phosphate phosphorus was total phosphate phosphorus and the 0.205±0.128 mg/1 and 0.035±0.063 combined concentrations of ammonia mg/1 as soluble orthophosphate and nitrate nitrogen was 13.11, slightly phosphorus. The maximum recorded phosphorus limited. Since the levels of each were 1.51 and 1.12 mg/1, abundances of these elements varied and the minimums were 0.036 and 0.0 through the year, the N-to-P ratio was mg/1, respectively. At Station 7 the not constant and ranged from less than 1 soluble orthophosphate concentration, to more than 80 (Fig. 8). From August of 0.076± 0.178 mg/1, was significantly one year through January of the next the higher than concentrations in the rest of ratio was usually less than 8, and the the lake (Brigham 1981), probably due to concentration of available nitrogen from the Tovey sewage the effluent approached phytoplankton- limiting treatment plant. Since Station 7 also had levels. This period was characterized by a significantly higher mean phytoplankton blue-green algal community. concentrations, it appeared that the phytoplankton abundance was correlated From February through July the N-to- with soluble orthophosphate concentrations. P ratio was usually greater than 8, and the phosphate phosphorus concentrations averaged about 0.15-0.20 mg/1, Sawyer (1947) reported that dropping below 0.05 mg P/1 for brief concentrations of 0.02 mg P/1 were periods. Diatoms and green algae were enough to support nuisance-algal the dominant plants during this time of growths, while Chu (1943 in Kuhl 1962) year. An algal bioassay by the U.S. stated that concentrations of 0.05 mg P/1 Environmental Protection Agency (1975) or less were limiting to such growths. concluded that Lake Sangchris was Since The phosphorus requirements vary phosphorus limited, because additions of with different species, this discrepancy is phosphorus produced a significant not unusual, and it does give a general increase in yield of Selenastrum idea of the range in which phosphorus capricomutum. The reported N-to-P may become limiting. On only three ratio was 35, and from the water occasions did total phosphorus levels accompanying the report approach what may have been chemistry data phytoplankton-growth-limiting (Brigham 1981) it seems that the water sample used for the bioassay was taken in concentrations: on 9 July 1974 (0.053 mg May, a period when the N-to-P ratio is P/1) immediately prior to a blue-green normally high (phosphorus is limiting). algal pulse, 17 December 1974 (0.039 mg P/1) prior to a winter diatom pulse, and Because algae are able to store 13 January 1976 (0.044 rng P/1) with a nutrients and use these reserves to diatom community. All of these periods support several cell divisions when were characterized by transitional environmental concentrations of phytoplankton communities of low nutrients are at limiting levels, instances density. of nutrient supply limiting a plankton Aug. 1981 Moran: Phytoplankton 337 Fig. 8, —The ratio ot nitrogen (nitrate N + ammonia N) to total phosphorus in Lake a: Sangchris, 5 September 1973-13 April 1976. The shaded band marks the optimal ratio of 8. S 'O'N'Dl J'F 'M'A'M'J' J'A'S'0'N"D| J'F'M'A'M'J' J'A'S '0'n'o| J'F'M'A' 1973 1974 1975 1976 pulse are often not evident. However, occurred, and this pulse was instances of silica limitation upon diatom accompanied by a drop in silica to about growth have been documented. Lund 2 mg/1. The decline of this pulse was (1950) found evidence that Asterionella accompanied by an increase of silica to formosa decreases coincided with drops more than 4 mg/1. in dissolved silica concentrations to below In March- April 1976 a pulse of a 0.5 mg Si02/1. Pearsall (1932) also minute diatom, Cyclotella pseudo- found that a silica concentration of about stelligera, was accompanied by a drop 0.5 mg Si02/1 was critical to diatom in silica, but water chemistry data ^ multiplication. Lewin & Guillard (1963) acquisition terminated at this point; so ' found the growth-limiting concentrations the extent of the drop is not known. The to be 0.1 mg Si02/1. frustules of this species were so small and In Lake Sangchris dissolved silica lightly silicified, however, that it seems concentrations had a mean annual unlikely that silica concentrations were I concentration of 3.573 mg/1 and were reduced to limiting levels. generally in excess of 2 mg/1 with the The ratio of silica and phosphorus has exceptions of November- December 1973 been suggested as possibly explaining I dynamics. Schelske : and March 1974. when concentrations some diatom (1975) dropped to 0.7-0.8 mg/1 (Fig. 9). Pulses reported that the mass ratio of Si02 to P of Melosira distans v. alpigena and M. in Asterionella ranged between 170 and ttalica occurred at those times, and the 500. Unpolluted tributaries of the Great heavily silicified frustules of these species Lakes have ratios greater than 500, and may have drained the silica supply to Tarapchak & Stoermer (1976) suggest a i nearly limiting levels. The decline of this ratio of 200 as being optimal for diatom ' pulse was followed by an increase in silica growth. In Lake Sangchris the mean to levels of 3 mg/1 or more. Si02-to-P ratio was 17.4, suggesting that In the following winter another pulse the phosphate concentration was capable of diatoms, primarily Synedra tenera, of supporting diatom growth to the point 338 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 ' 12 ' II 10 9 8 • 7 o H 6 4 • 5 4 • 3 2 'oInIoIjIf'm'a'm'o'j'a'sIoInIdIj'f'JaImI.IjIaIsIoInIdIjIfImIa'm'jIj 'a's 1973 1974 1975 1976 Fig. 9. — Dissolved silica (mg Si02/I) and diatoms in Lal where silica would become limiting, total phosphate phosphorus concen- thus removing diatoms from nutrient trations were in excess of 0.10 mg, 1. In competition and allowing for increased general, it appeared that neither silica growths of green and blue-green algae. nor phosphorus depletions were responsi- The ratios of silica and total ble for the decline of diatom pulses. phosphate were examined before, PRIMARY PRODUCTIVITY during, and after three major diatom this several techniques pulses (Table 5). As expected, the ratios During study of silica to phosphorus declined during were employed to estimate primary each pulse. In May 1974 the silica production. Since each method measured concentrations approached what may a different reaction in the photosynthetic have been a phytoplankton-growth- process, their combined use gave a good limiting concentration of silica (0.8 estimate of photosynthetic activity in the mg/1), and the Si02-to-P ratio was 4.4. lake. This pulse of Melosira spp. may have The 'ipH-C02 and ^02 methods been limited by silica depletion. were used to measure photosynthesis However, the diatoms were not replaced under natural conditions while light-dark in importance by any other group; so bottle experiments were being other factors may have been responsible conducted. The light-dark bottle for the decline rather than silica experiments used the ^pH-C02, 02. depletion. The other pulses were or the 14c methodology. The mean composed of the small, lightly silicified ^02-determined photosynthetic rate was cells of Synedra tenera and Cyclotella 5.34 mmol 02/m3-hr, and the mean pseudostelligera, and the ratio did not of the '^pH-C02-determined rates was drop below 20.4. At these times the mean 6.77 mmol C02/m3. hr. The overall surface water concentrations of dissolved mean was 5.52 mmol C02/m 3. hr. For silica were in excess of 2 . 1 4 mg/1 , and the comparative purposes, the oxygen Table 5. — Ratios of silica to total phosphate phosphorus (3102?) before, during, and after diatom pulses in Lake Sangchris. Period Pulsing Before During After Species Pulse Pulse Pulse Mar. -May 1974 Aug. 1981 Moran: Phytoplankton 339 production rates were converted to CO2 uptake rates by a factor of 0.80 x (Ryther 1956). The 14c data, while showing the same trends as the other methods, yielded much lower carbon uptake rates. Generally, the 14(] data lowered the mean photosynthetic rates by about 12 percent during the cool-water periods and 30 percent during the warmwater periods. The data were divided into two periods based upon discharge water temperatures (Table 6). When discharge temperatures equalled or exceeded 30°C at Station 5, the period was classified as a warmwater period, and when temperatures were less than 30°C at the discharge, it was considered a cool-water period. During the warmwater period (June- September) the mean rate, 4.18 mmol C02/m3- hr, was about 11 percent higher than the mean for the cool-water period, 3.77 mmol C02/m3- hr. During the cool-water period, the photosynthetic rate at Station 4 in the discharge arm was similar to those of stations 2 and 3 in the Table 6. —Summary of primary productivity, mmol C02/m3 hr (standard deviation in parentheses), in the photic zone of Lake Sangchris from 16 October 1973 through 14 September 1976. Means underscored by the same line are not significantly different at the 05 level (after the Student-Newman-Keuls multiple range test). Station 5 Station 5 at or above 30°C below 30»C Station (June-September) (October-lVlay) 1 340 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 cooling-loop stations ofi an annual basis indicating that the lake was moderately as well as during the spring and autumn productive. periods. The significantly higher soluble 9.— When discharge water orthophosphate phosphorus concentra- temperatures exceeded 30''C, primary tions in the control arm may have been a productivity was significantly reduced in contributing factor. the discharge canal and discharge arm. 3.— Species diversity (H') seldom The inhibition was temporary, and exceeded a value of 3 and was 1 or less photosynthetic capability was restored by during the blue-green and diatom the time the water mass had reached the blooms. Evenness of the species Station 3 area, half way around the distribution (J) did not exceed a value of cooling loop. 0.42, indicating that the highest species 10.— The operation of the Kincaid diversities were due to the population size Generating Station was generally not rather than the evenness of species deleterious to the phytoplankton. The distribution. constant circulation of water around the 4. —Distribution of phytoplankters cooling loop prevented permanent throughout the lake and bays was stratification and maintained a high uniform, indicating that the turbulent degree of spatial homogeneity in the flow and side arm circulation in the bays phytoplankton. Condenser passage did kept the lake water well mixed. not produce any differences among the in the intake 5.— A 1 -month shutdown of the phytoplankton communities generating station in August 1976 and discharge canals although primary resulted in water temperatures being productivity was temporarily depressed 6°-ll°C below the seasonal norm and when discharge water temperatures caused the temporary collapse of a exceeded 30°C. The control arm had blue-green algal pulsed during that significantly higher productivity rates period. and usually had the highest concentrations of phytoplankters, 6. The mean N-to-P ratio was probably a result of the higher soluble ! 13.11 and varied from less than 1 in the orthophosphorus concentrations in that autumn to more than 80 in the spring. area. Nitrogen approached phytoplankton- growth-limiting levels in the autumn, and phosphorus concentrations approached REFERENCES CITED levels on a few occasions but did limiting Brigham, a. R. 1981. Water quality in a cooling not appear responsible for limiting any water reservoir. Pages 290-319 in R. W. Tranquilli, eds.. The Lake phytoplankton blooms. Larimore and J. A. Sangchris study: case history of an Ilhnois cooling 7. —The annual mean concentration lake. Illinois Natural History- Suney Bulletin of silica was 3.573 mg/1, and the mean 32(4). Cairns, Jr. 1956. Effects of increased Si02 - to - P ratio was 17.4. Silica J., temperatures on aquatic organisms. Industrial limitation may have been responsible for Wastes 1:150-152. the termination of a Melosira spp. bloom CouTANT, L. 1977. Algal dynamics of Lake Sang- in 1974, and while later blooms of other chris and Lake Shelbyy'ille. Pages 5-1-5-44 m diatom species caused some decline in Evaluation of a cooling lake fishery. \'ol. 4. Prepared by Illinois Natural History Survey for silica levels, the silica concentrations did Electric Power Research Institute. Palo .\lto. CA. levels. not approach limiting CsANADY, G. T. 1964. Turbulence and diffusion in the Great Lakes. Pages 326-329 m University of 8. — Primary productivity was Michigan Great Lakes Research Division Publica- significantly higher in the control arm tion 11. than it was in the cooling loop. Evans, D.. and J.G. Stockner. 1972. Attached Productivity in the warmwater periods algae on artificial and natural substrates in Lake Winnipeg, Manitoba. Canada Fisheries Research (summer) was greater than it was in the Board Journal 29:31-44 cool-water periods. The mean net FiNDENEGG, I. 1974. Expressions of populations. photosynthetic rate, excluding the '^c Pages 16-18 in R. A. Vollenweider. ed., A data, was 5.52 mmol C02/m3- hr. manual on methods for measuring primary pro- Aug. 1981 Moran: Phytoplankton 341 duction in aquatic environments. Blackwell Shannon. C. E., and W. Weaver. 1949. The Scientific Publications. London 225 p. mathematical theory of communication. Focc. G. E. 1975. Algal cultures and phytoplankton University of Illinois Press. Urbana. 117 p. ecology. 2nd ed. University of Wisconsin Press, Stewart, W. D. P., ed. 1974. Algal physiology Madison. 175 p. and biochemistry. Botanical Monographs. Vol. KuHL. A. 1962. Inorganic phosphorus uptake and 10. University of California Press, Berkeley. 989 p. metabolism. Pages 211-229 in R. A. Lewin, ed.. SwEERS, H. E. 1970 Vertical diffusivity coefficient Physiology and biochemistry of algae. Academic in a thermocline. Limnology and Oceanography Press, New York. 15:273-280. L. Guillard. 1963. Dia- Lewin, J. C, and R. R. toms. Annual Review of Microbiology Tarapchak. S. T. and E. F. Stoermer. 1976. 17:373-414. Environmental status of the Lake Michigan region. Studies on Asterionella Vol. 4, Phytoplankton of Lake Michigan. Lund, J. W. G. 1950. formosa Hass. II. Nutrient depletion and the Argonne National Laboratory, Argonne, IL. 21 p, spring maximum. Journal of Ecology 38:1-14, U.S. Environmental Protection Agency. 1975, 15-35. Report on Sangchris Lake, Christian County, Morgan, R. P.. and R. G. Stross. 1969. Illinois. Working Paper No. 314. Corvallis Destruction of phytoplankton in the cooling Environmental Research Laboratory. Corvallis, water supply of a steam electric station. OR. Chesapeake Science 10(3-4):165-171. Verduin, 1956. Primary productivity in lakes. Nauwerck, a. 1963. Die Beziehungen zwischer J. Limnology and Oceanography 1:85-91. zooplankton und phytoplankton in See Erken. . Reservoir problems Symbolae Botanicae Upsalienses 17(5):93-154. 1967. management created by increased phosphorus levels of surface Palmer, C. 1962. Algae in water supplies. Public waters. Pages 200-206 in Reservoir fishery Health Service Publication 657. Robert A. Taft resources symposium. American Fisheries Socie- Sanitary Engineering Center, Cincinnati. 88 p. ty, Division, Washington viii •¥ Pearsall, W. H. 1932. Phytoplankton in the Southern DC. 569 English lakes. 2. The composition of the p. Phytoplankton in relation to dissolved substances. VoLLENWEiDER, R. A. 1974. Methods of measuring Journal of Ecology 20:241-262. production rates. Pages 51-152 in R.A. for PlELOU, E. C. 1975. Ecological diversity. J. Wiley Vollenweider, ed., A manual on methods & Sons, New York. 165 p. measuring primary production in aquatic environments. Blackwell Scientific Publications, Prowse, G, a., and J. F. Talling. 1958. The seasonal growth and succession of plankton algae London 225 p. Nile. Oceanography in the White Limnology and Waite, S. W. 1977. Zooplankton dynamics of Lake 3:222-238. Sangchris, October 1975 through October 1976. limnology. RuTTNER, F. 1963. Fundamentals of Pages 2.1-2.24 in Annual report for fiscal year University of Toronto Press, xi + 242 p. 1976, Lake Sangchris Project. Illinois Natural measurement of primary RvTHER. J. H. 1956. The History Survey, Urbana. production. Limnology and Oceanography Weber, C. ed. 1973. Plankton. Pages 1-20 .in 1:72-84. Biological field and laboratory methods for Sawyer, C. N. 1947. Fertilization of lakes by measuring the quality of surface waters and agricultural drainage. New England Water effluents. U. S. Environmental Protection Agency Works Association Journal 61:109-127. Publication EPA 6701/4-73-001. Cincinnati, OH. ScHEUKE, C. L. 1975. Silica and nitrate depletion Woelkerlinc, W. R. R. Kowal, and S. B. as related to rate of eutrophication in Lakes J.. GoucH. 1976. Sedgwick-Rafter cell counts: a Michigan, Huron, and Superior. Pages 277-298 procedural analysis Hydrobiologia 48:95-107. m A.D. Hasler. ed.. Coupling of land and water 1974. Biostatistical analysis. Prentice- systems. Ecological Studies. Vol. 10. Springer- Zar J. H. Verlag, New York. Hall, New Jersey. 620 p. Effects of Cooling Lake Perturbations upon thie Zooplankton Dynamics of Lake Sangchris Stephen W. Waite ABSTRACT index values of zooplankton in Lake Sangchris were highly variable, with dif- The limnoplankton of power plant ferences and similarities attributed to cooling lakes are subject to many atypical seasonality and erratic power plant environmental conditions. discharge conditions. There was no The purpose of this investigation was evidence of significant differences (0.05 to determine the effects of entrainment level) of the diversity of zooplankton on the density of zooplankters and of populations in the intake and discharge heated discharge water on the seasonal canals. periodicity, composition, diversity, and standing crop of these organisms in Lake The standing crop of zooplankters in Sangchris, a cooling lake in central Il- Lake Sangchris was highest during early linois. spring, decreasing through late spring An analysis of water chemistry data and summer. This trend was unlike that showed that no chemical limitations were in unheated lakes, where biomass is imposed on the zooplankters during the generally highest during late spring or study. summer. Injune and July, secondary pro- While most zooplankton records from duction in all Lake Sangchris cove sta- this lake are typical of midwestern lentic tions was well within or above the range systems, several typically common of open lake values (0.4—0.6 kcal m~ ^), species, including Leptodora kindtii and but in late autumn and winter, cove pro- Diaptomus pallidtis, were noticeably ab- duction decreased to levels below those in sent from Lake Sangchris. all nearby lake stations. A comparison of Several traditionally dicyclic species autumn and early winter zooplankton became monocyclic in the heated system, production of the open-water regions at indicating that possibly the interrelated Lake Sangchris and Lake Shelbyville in- biological and physicochemical dicated generally higher values in the parameters in Lake Sangchris favored former, with production in Lake continual growth and reproduction for Sangchris significantly higher in these forms. The lifetime for some Lake November. Sangchris zooplankters (especially Generally, the addition of heat in rotifers) appeared to increase or decrease Lake Sangchris provided a potential depending upon the temperature enhancement for zooplankton com- preference of the individual species; these munities during autumn, winter, and increased growing periods probably spring, but in late summer, thermal resulted in greater fecundity and total loading resulted in an obvious reduction production. The number of zooplankton in numbers and biomass. species in the cooling loop was relatively constant throughout the year, a trend unlike that recorded for the control arm INTRODUCTION or for Lake Shelbyville. Species diversity Both plant and animal constituents of the limnoplankton inhabiting electrical Stephen W. Waite is a Research Associate, power plant cooling reservoirs are subject Section of Aquatic Biology. Illinois Natural History Survey. to a wide variety of artificially induced en- This chapter submitted in Oct. 1977. vironmental alterations. While some 342 Aug. 1981 Waite: Zooplankton 343 result from the addition of chlorine and was originally located centrally within the other biocides, others are mechanical discharge canal, but in 1975 this station forces acting within the plant itself; these was moved to the junction of the canal include turbulence, pressure, vacuum, and and the reservoir basin to facilitate physical contact with the various screens, sampling. Stations 2,4, and 7 are similar pumps, and tubes (Kedl & Coutant in morphometry although current 1976). One factor posing a threat to the velocities are proportionate to their plankton in a cooling lake is the heat distances from the discharge canal. Five discharged via large volumes of condenser additional stations in coves A, B, C, D, cooling water. Depending on thermal and X (Fig. 1) were added in May 1976 to loading, discharge volume, and current compare the littoral communities of the velocity, and the cooling-lake mor- cooling loop and the control arm. Water phology, the energy supplement from the depths in these littoral areas never ex- waste heat is reflected in most lim- ceeded 2 m. noplankton populations at a particular level, thus identifying certain thermal conditions that may be detrimental or METHODS beneficial to the ecosystem. monitoring phase The effects of heat on the During the samples were zooplankton of Lake Sangchris for the (1973-1974) zooplankton taken with a plankton pump. One first 2 years of this study (1973-1974) were biweekly determined primarily by monitoring 65-liter volume was pumped the 1-m and 5-m depths at each sta- species population trends and determin- from were strained through a no. ing the effects of condenser passage on tion. Samples 20 mesh Wisconsin net, reducing the : soft -bodied organisms (Brigham et al. original sample to 60 ml, and were then I 1975). While those data satisfied the re- preserved with Neosynephrine quirements of the initial phase of the pro- fixed and and 5-percent formalin, respectively. ject, I focused specifically in the 3rd year Zooplankters were identified, counted, on (1) seasonal periodicity, composition, numbers per liter of lake abundance, and diversity of zooplankton and recorded as water. species and (2) standing crop and calorific fish-food value comparisons of For the more intensive studies con- the zooplankton biomass in littoral as well ducted during 1975, three vertical hauls as limnetic communities of this cooling (replicates) were procured monthly from reservoir. Analyses of the final year's data the same limnetic stations using a 30-cm were enhanced by comparing the data to diameter conical plankton net with those obtained by similar sampling SOjim nylon mesh. Beginning in May techniques in Lake Shelbyville, a nearby 1976, an additional three replicates also noncooling reservoir. were taken monthly, using an 11 -cm diameter Wisconsin net (80^ m mesh), from each of five isolated coves. All con- samples were fixed and preserv- DESCRIPTION OF THE centrated ed in a 5-percent formalin and 50-percent STUDY AREA alcohol solution tinted with rose bengal stain. During the initial monitoring phase of efficient working this study, six sampling areas, represent- To obtain the most ing the various limnetic regions, were density, the concentrated samples were on the chosen for the warmwater discharge and diluted to 25 to 200 ml, depending density intake arms and the cold-water control volume of water strained and the original lake water. [arm (Fig. 1). Located near midchannel, of organisms in the replicate these sampling stations are lentic habitats Three 1-ml subsamples of each Rafter with depths ranging from 5 to 12 m. Sta- were placed in gridded Sedgewick- and enumeration tion 5, representing the discharge region, cells for identification 344 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 POWER PLANT Fig. 1. —Zooplankton sampling stations in Lake Sangchris. Stations 1, 2, 3, 4, 5, and 7 represent limnetic regions of tine lake basin, while A, B, C, D. and X represent littoral areas in the cooling loop and control arm. of species. The remaining portion was ash-free biomass units (mg) per cubic poured into a petri dish, and taxa not meter. Approximations of the calorific observed in the subsamples were recorded value of the total biomass were computed and computed. Identifications were from equations by Winberg (1971). made using a stereo dissecting microscope An account of the total zooplankton with 1:4 zoom range (lOx to 40x) and a species diversity was characterized by an trinocular compound microscope at index (d) based on the methodologies of lOOx to 400x. Species identifications for Wilhm & Dorris (1968) and Patten (1962). the entire project were based on publish- ed keys by Ahlstrom (1940 and 1943), RESULTS AND DISCUSSION Pennak (1953), Brooks (1957 and 1959), COMMUNITY DYNAMICS Edmondson (1959), Wilson & Yeatman Species Composition (1959), and Goulden (1968). All samples collected during 1975 Twenty-nine species of rotifera and 38 were filtered, dried, and ashed at 500''C microcrustaceans were collected from for 1 hour to determine estimates of the October 1973 to October 1976 (Table 1). zooplankton standing crop in dry and Other constituents of plankton included Aug. 1981 Waite: Zooplankton 345 Table 1. — Distribution of rotiferan and crustacean zooplankters collected from open-water stations 1, 2, 3, 4, 5, and 7 and littoral cove stations A, B, C. D, and X in Lake Sangchris. Species indicated by a superscript letter (a) are those not collected in Lake Sheibyviiie. 346 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 1 . —Continued. Aug. 1981 Waite: Zooplankton 347 species was observed only once shown in Table 2. Several taxa, including; (December 1975) at Lake Sangchris. Brachionus angularis, Polyarthra, Syn- Although it is a summer form, it may chaeta, Bosmina longirostris, and Diap- never have been introduced successfully tomus siciloides, were observed into this watershed, or possibly it could throughout the year, while Chydorus not tolerate discharge turbulence or sphaericus and Daphnia parvula were temperatures exceeding SO^C. Another common species on virtually all sample explanation suggests that the few in- dates. Most other species were somewhat dividuals collected in December 1975 dicyclic, but others were monocyclic or may have been transported to the reser- very sporadic; the latter included the voir by wildfowl migrating southward. crustaceans Alona, Pleuroxis, Camptocer- One of the most common North cus, and Eucyclops speratus, which American cyclopoid copepods, typically inhabit the more shallow, Macrocyclops albidus, was never observ- weedy areas. Since this information in- ed in Lake Sangchris until 1975, when it dicates only general trends in a particular was collected in coves and other aquatic system, little or no effect on backwaters. Paracyclops fimbriatus pop- zooplankton periodicity can be attributed pet and Tropocyclops prasinus are also to the operation of the generating plant. common and widespread lentic forms on However, some traditionally dicyclic the North American continent, but their species (particularly the crustaceans) presence in Lake Sangchris was limited to became perpetual in the heated system, a very brief occurrence during the indicating that possibly the interrelated monitoring phase of this study biological and physicochemical factors in (1973-1974). Lake Sangchris favored continual growth An analysis of water chemistry data and reproduction for these forms. no (Brigham 1981) suggests that few or Brigham & Moran (1974) suggested chemical limitations were imposed on the that "heat tolerant" species in Lake zooplankton in Lake Sangchris. Since Sangchris should become abundant most species of Cladocera and Copepoda sooner than "less tolerant" forms. But the can withstand oxygen concentrations of data showed that abundance peaks were less than 1 ppm, the amount of dissolved inconsistent and that population densities oxygen in Lake Sangchris was of little increased from the relatively shallow significance except in the hypolimnion discharge canal to the deeper regions ad- ox- during short periods of thermal and jacent to the dam. In view of these data, ygen stratification (Brigham 1981). The lake basin morphometry and not heat in- most easily recognized parameter affect- put was suggested by Brigham as the ing zooplankton survival is pH, or rather primary influence on zooplankton the complex of physicochemical periodicity. variables, each of which by itself may be In 1976 I disregarded Brigham's capable of affecting species composition. peak-of- abundance theory and The large majority of rotifers are hypothesized that in a heated lake, "transcursion" species that occur in both temperature increases above ambient — acid and alkaline waters (pH 4.1-8.5), may induce longer or shorter growing and most Cladocera occur in waters hav- periods for wantiwater (summer) and ing a pH of 6.5-8.5. Since the pH of Lake cold-water (winter) species, respectively. Sangchris ranged from 6.7 to 9.5 during This hypothesis was based on a suggestion the study (Brigham 1978), there was little by Gibbons (1976) that certain chance that it was a limiting factor to temperature elevations in a cooling most zooplankton constituents. system might provide an extension of seasonal species duration, a situation Periodicity of Species which may produce more offspring dur- The periodicity of selected species ing normally nonreproductive periods (only those species collected in at least 2 (Gibbons 1976). In addition, the animals of the 3 study years were considered) is would grow larger, and this increased 348 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 size, coupled with higher temperatures, an analysis of the seasonal duration of could result in increased filtering and zooplankton in Lake Sangchris, a com- feeding rates (Waite 1976). To facilitate parison of species common to Lake a> cn na> o o O D J3 E 0) Q. 05 w Aug. 1981 Waite: Zooplankton 349 Sangchris and Lake Shelbyville was made, during May and June but was observed based on data accumulated from July only in the April collections from Lake 1975 through March 1977 (Table 3). Sangchris. Hexarthra sp., a typical late RoTiFERA. — Representatives of the summer form, was found only in August loricate family Brachionidae had the at Lake Shelbyville, but in Lake greatest variation of seasonal duration in Sangchris this soft-bodied form was the two reservoirs. A typical summer prevalent from July through September. species, Brachionus caudatus, was Feeding on chrysomonads and proto- observed from July to September in Lake zoans, Synchaeta sp. populations were Shelbyville, but in Lake Sangchris this dicyclic in both reservoirs; their longest species occurred 2 months earlier in May. growing period in Lake Sangchris was Likewise, B. calyciflorus, a common early winter to early summer, whereas the species that usually reaches its peak abun- interval at Lake Shelbyville was July to dance in July or August, was collected November. Occurring all year at Lake lakewide most of the year in Lake Sangchris, Filinia longiseta was collected Shelbyville but was found in Lake only from May to September at Lake Sangchris only during spring, midsum- Shelbyville. mer, and late autumn. A typical cool- Cladocera. —Usually observed in water form, B. urceolaris, was common winter and spring, Bosmina longirostris I from November to May in the unhealed was a common inhabitant in the heated I lake, but in Lake Sangchris it was lake most of the year. Inhabiting the bot- 1 restricted to late winter and early spring. tom ooze during most of its life history, II- One of the most common brachionids, B. yocryptus sordidus was found in the angularis, reproduced throughout the Sangchris plankton only during July, yet year in Lake Sangchris, but its growing in Lake Shelbyville it was collected in season in Lake Shelbyville was restricted March, August, and September. While to a 7-month period. Although Keratella Ceriodaphnia quadrangula was collected quadrata populations usually peak in June from early summer to November in Lake and move to the cooler hypolimnion Shelbyville, this species was dicyclic in before declining in midsummer, this Lake Sangchris. species was collected in Lake Shelbyville CoPEPODA. — Common to Lake Table 3, —A comparison of seasonal occurrences of zooplankton species common to lakes Sangchris and Shelbyville. Monthly collections were made from July 1975 through March 1977, 1 axa 350 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Shelbyville all year, Cyclops vemalis was large spring pulse; a decreased dicyclic in Lake Sangchris in late spring population during the summer; and a and autumn, -while Mesocyclops edax ap- second, less pronounced pulse in the fall, peared in the heated reservoir 2 months followed by a very small population in earlier than in Lake Shelbyville. The ap- winter. Furthermore, the number of pearance of Macrocyclops albidus seemed species may also follow a somewhat random in both lakes, and thus no similar pattern unless the natural specific trends were associated with this periodicity is modified or eliminated by species. various biological, chemical, or physical These preliminary observations led parameters. me to conclude that the reproductive The mean numbers of zooplankton period for some Lake Sangchris species in Lake Shelbyville are compared zooplankters (mostly rotifers) appeared to to the mean numbers in the cooling loop increase or decrease depending upon the and control arm of Lake Sangchris from temperature preference of the individual September 1975 to May 1977 (Fig. 2). As species. Increased growth periods could is typical of nonheated reservoirs in this result in increased fecundity and produc- region, the mean number of Lake tion of zooplankters during normally Shelbyville species decreased to 6 during nonreproductive periods, thus the winter but increased to 16-19 species precipitating the development of a more in the spring and early summer. substantial food base for newly hatched Likewise, conditions in the cold-water fry and young-of-the-year planktivorous control arm in Lake Sangchris resulted in fishes. Such data, combined with biomass a similar curve but with less variability estimates, would be of great practical im- and slightly fewer species. In contrast, the portance to fishery scientists interested in cooling loop had 9-11 species during creating conditions conducive to autumn and winter and gradually in- increased fish production in cooling creased to 15 species by midsummer. reservoirs. However, a <-test analysis revealed no evidence of significant differences (0.05 Number of Species level) among the three monthly means for Many classical zooplankton studies any particular sample date. Thus, while have shown that the abundance of these the number of species in the cooling loop organisms undergoes extensive seasonal did not exhibit the classical seasonal fluc- variation. The typical curve of seasonal tuations observed in Lake Shelbyville, zooplankton abundance usually has a there were no indications of complete = LAKE SHELBYVILLE = LAKE SANGCHRISy CONTROL ARM 22 = LAKE SANGCHRIS., COOLING LOOP 18 14 10 SEPT. NOV, JAN. MAR, MAY JUL. SEPT. NOV. JAN. MAR, HAY OCT. DEC. FEB, APR, JUNE AUG. OCT. DEC, FEB, APR. 1975 1976 1977 Fig. 2. —A comparison of the total number of zooplanl ' species suppression, but rather I observed duration of ice cover in this lake is a damping effect that allowed little an- relatively short compared to that on nual variability of species numbers. unheated lakes, greater light penetration While these observations may seem and warmer water temperatures are unimportant, the ecological significance certain to affect species composition, may be noteworthy in terms of the im- succession, and standing crop from late mediate relationships of primary and autumn through spring, i. e., cold-water, secondary producers and ultimately of low-light adapted species are limited to a the entire trophic structure. Coutant shorter period while warmwater species (1977) showed that algal populations in are present later in autumn and earlier in Lake Sangchris have had fewer highly spring (see previous section). pronounced blooms and declines than the Although damping of the lower populations in other lakes. According to trophic levels in Lake Sangchris from Wetzel (1975), the seasonal amplitude of autumn through spring defies the the maximum and minimum of classical theory regarding the winter phytoplankters in temperate waters is decline and spring blooms of plankton, usually very large (one thousandfold), but this condition may be an enhancement by the amplitude in Lake Sangchris was only providing a stabilized food base for such fiftyfold, a level more nearly approaching secondary and tertiary consumers as the fivefold to tenfold difference of invertebrate predators and planktivorous tropical lakes. fishes. Probably the most important conse- quences of this damping of the lower Species Diversity trophic levels are the atypical relation- Analyses of zooplankton communities ships of the plankton and the were aided by using the species diversity physicochemical limnology of the cooling index (d) (Wilhm & Dorris 1968) to lake basin from winter through spring. express a relationship between (1) the The winter phyto- and zooplankton con- richness of species in a community and stituents in most lakes and reservoirs are (2) the distribution or evenness of cold-water, low-light adapted species that individuals among those species. can survive only within a narrow range of Although the index is used primarily to conditions. Spring circulation, which evaluate terrestrial and benthic biotopes, follows the loss of ice cover, results in the it can also characterize the degree of mixing of nutrients from the hypolim- stress affecting zooplankton , nion, and these particles, combined with communities, as well as compare the increasing light levels, contribute to the relative conditions of populations in typical synchronous blooms of phyto- and different habitats. Unlike low values of zooplankton populations in the spring. benthic diversity, however, low In Lake Sangchris, however, heated zooplankton values may not necessarily discharge waters and the continuous be indicative of a fatal stress; rather, such circulation were probably directly related values could indiciate a period when to the damping phenomenon. Continual species succession is occurring or when mixing of water, especially in the cooling diversity and abundance are normally I loop, prevents winter stratification; low, i.e., during the winter months. hence, few or no nutrients are available Therefore, data should be carefully for the typical burst of spring analyzed before assessing the reasons for phytoplankton growth. The formation of low values. ice, which limits light penetration, was Index values of the limnetic prominent in Lake Sangchris only in the zooplankton (Rotifera, Cladocera, and vicinity of the intake arm, in the control Copepoda) diversity in Lake Sangchris arm, and in coves adjacent to the ranged from 0.18 to 3.00 from September warmwater arm. Additionally, since the 1975 to October 1976 (Table 4). For most 352 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 4. —Variation of species diversity index values (d) for limnetic zooplankton populations in Lake Sangchris, September 1975 to October 1976 Aug. 1981 Waite: Zooplankton 353 EFFECTS OF CONDENSER and ash-free biomass per unit volume or PASSAGE surface area and/or (2) estimations of g~l There are several conflicting reports calorific values (kcal of dry weight) unit or in Kittitsina (1973) regarding the per volume surface area. condition of zooplankters after passing This investigation has shown that the through power plant condensers. A standing crop of pelagic zooplankton in a number of investigators from the United heated reservoir undergoes many seasonal States, Asia, and eastern Europe have variations (Table 6). The standing crop reported that the organisms become in Lake Sangchris was highest during traumatized when passing through early spring, decreasing through late condenser units and lose up to 50 percent spring and summer. This trend was for the in biomass and numbers. In contrast, opposite that recorded unheated other studies in the U.S.A., and Lake Shelbyville system, where the particularly studies in Great Britain, biomass was highest during late spring show that the zooplankton remain viable and summer. In Poland, Sherstyuk observed that in after passing through the tubes. Likewise, (1971) also unheated the late winter plankton the latter situation appeared to be the lakes spring and the highest and lowest values, case in Lake Sangchris, because during had the 2 years of monitoring (1973-1974) respectively. several interrelated factors there was little difference between the Probably system result in intake and discharge canals in numbers of acting on a heated species and organisms collected. decreased biomass during the summer. However, that investigation did not One theory suggests that entrainment zooplankton determine whether the animals in the may significantly reduce the periods discharge samples were dead or alive at biomass, erpecially during of production. the time of collection or the length of peak electrical power shown time the animals were viable after passing Kittitsina (1973) in Lithuania has in the through the condensers. evidence of a 50-percent decrease abundance and biomass of the STANDING CROP zooplankton fauna during summer. Standing crop is a general index However, in Lake Sangchris the number of reflecting the sum total of all biotic and organisms may not have been reduced abiotic interrelationships. In aquatic significantly after passing, through the systems, it can be expressed as (1) the dry condensers. Davies et al. (1976) suggest Table 6— Mean zooplankton biomass (mg m-3) of Lake Sangchris sampling stations, with a comparison to the mean in Lake Shelbyville, October 1975 to October 1976. 354 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 that either zooplankters remain viable receiving waters support a plankton after condenser passage, or the discharge recovery rate capable of compensating LAKE SANGCHRIS LAKE SHELBYVILLE 3 JUNE JUNE 2 1 1 JULY -\ JULY 0-^ 1-1 AUGUST en -LU CO a: - OCTOBER _J 1.3 — 0.2- 0.2- 0.1- STATION STATION Fig. 3. —A comparative summary of the production of littoral and pelagic zooplankton collected from Lake Sangchris and pelagic zooplankton of Lake Stielbyville, The solid lines represent the number of kilocalories available per m3 at cove stations A, C, D, and X in Lake Sangchris and open- water stations 1 , 2, 3, 4, 5, and 6 in Lake Shelbyville, The dashed lines indicate the range of calorific values computed from all open-v\/ater stations in Lake Sangchris. Aug. 1981 Waite: Zooplankton 355 for entrainment mortality. My in the Lake Sangchris coves by reducing calculations from the ashed biomass data the mortality rates of warmwater species revealed that the small reduction of subjected to sublethal or lethal water biomass due to entrainment probably was temperatures. Therefore, the null offset by the addition of organisms via the hypothesis was rejected, because during slag pond overflow at the discharge the warmer months, increased water canal (Fig. 1). temperatures in pelagic regions resulted The second theory cites water in less biomass there compared with the temperatures as the most influential standing crops in coves and other littoral factor affecting heated aquatic systems. regions. Although the monitoring studies of the In addition, this study revealed that first 2 years examined the reaction of the some zooplankton assemblages may be drifting plankton to heated effluents, enhanced by the atypically warmwater little was done in regard to temperatures encountered during late planktobenthic organisms inhabiting the autumn and winter. A comparison of many side coves. To determine if the autumn and early winter production of standing crop of zooplankton in these the open-water regions of Lake Sangchris regions reflects the effects of heated and Lake Shelbyville indicated generally waters to the same extent as do their higher values in the former from pelagic counterparts, I hypothesized that September through October. Moreover, the zooplankton standing crop in the Lake Sangchris production was coves was significantly decreased during significantly higher (0.05 level) in the warmer months due to a combination November, which provides a possible of shallow water and the circulation of additional explanation for the increased heated water into the coves. abundance of the largely planktivorous In making estimates of mean lakewide yellow bass in the discharge canal relative production of zooplankton (measured in to that in the intake canal in cold months available energy units per unit volume) in (J. A. Tranquilli, personal communica- Lake Shelbyville, pelagic production was tion). Kittitsina (1973) noted that in compared with cove production in Lake various Soviet lakes heating stimulated Sangchris from June through December zooplankton development in autumn and 1976 (Fig. 3). In June and July, winter, and the peaks of abundance and production in all Lake Sangchris cove biomass during these seasons were most stations was well within or above the evident in the discharge zone. Conse- upper range of open-lake values (0.4-0.6 quently, the addition of heat provided a kcal m'3), but in late autumn and winter, potential enhancement for the system cove production decreased to levels below during winter, but in summer, thermal those in all nearby lake stations. loading resulted in zooplankton density Production in Lake Shelbyville, however, and biomass reductions in the pelagic was highest during the summer regions, with the coves serving as sanc- (sometimes higher than in Lake tuaries during the hottest months and Sangchris), but dropped to lower levels providing a continuing food base for during the autumn and winter. young-of-the-year planktivorous fishes. When the temperature rose during the summer in Lake Sangchris, SUMMARY zooplankton production in the main The chemical parameters associated channel was significantly lower than it with electrical power production did not was in the coves. Harleman et al. (1976) impose any detectable limitations on the showed that heated water circulating into Lake Sangchris zooplankton during this side coves suffers a heat loss at the air- study. water interface, resulting in somewhat While most zooplankton records from cooler water temperatures than those in Lake Sangchris are typical of those of the main channel. This cooling effect midwestern lake systems, there were probably enhanced zooplankton survival several notable absences, including the 356 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 largest cladoceran, Leptodora kindtii, a nearby open-lake stations. A comparison common inhabitant of other lakes in of open-water production at Lake Illinois. Sangchris and Lake Shelbyville indicated generally higher values in the Several traditionally dicyclic species former, with production in became perpetual in the heated system; Lake Sangchris significantly higher in November. this phenomenon was a possible Generally, the addition heat indication that the complex of biological of and the resulting physicochemical conditions and physicochemical parameters in Lake Sangchris favored continual growth and in Lake Sangchris provided a potential enhancement for the system reproduction for these organisms. during autumn, winter, and spring: however, in The reproductive periods of some summer, thermal loading resulted in Lake Sangchris zooplankters (especially zooplankton density and biomass rotifers) appeared to increase or reductions in the open-water regions, decrease, depending on the temperature while coves apparently served as preference of the individual taxon; the sanctuaries to reinoculate these regions increased periods probably enhanced the when conditions for growth and population by increasing total production reproduction were improved. during normally nonreproductive periods. Species having increased growth periods during the spring in Lake Sangchris may contribute to a more REFERENCES CITED substantial food base for the newly hatched planktivorous fishes. Ahlstrom, E. H. 1940. A revision of the rocatarian genera Brachionus and Platyias with A comparison of the zooplankton descriptions of one new species and two new species collected in Lake Sangchris and varieties. American Museum of Natural History' those found in Lake Shelbyville revealed Bulletin 77:143-184. 1943. A revision of the rotatarian genus that the numbers of species in the cooling Keratetla with descriptions of three new species loop of the former did not exhibit the and five new varieties. American Museum of traditional seasonal fluctuations of the Natural History Bulletin 80:411-457. species in the latter, but experienced a Brigham. A.R.. and R. L. Moras. 1974. Plankton damping effect that resulted in little investigations at Lake Sangchris 5 September September 1974. Pages 2.1-2.97 annual variability of species numbers. 1973 through 4 in Annual report for fiscal year 1974. Lake Species diversity index values of Sangchris project. Illinois Natural History- Survey, Urbana. zooplankton in Lake Sangchris were . Water quality in a cooling water highly variable, with differences and 1981. re5er\oir. Pages 290 319 in R. W. Larimore and similarities attributed to seasonality and J. .A. Tranquilli. eds.. The Lake Sangchris study: erratic power plant discharge conditions. case historv of an Illinois cooling lake. Illinois There was no evidence of significant Natural History Survey Bulletin 32(4). differences (0.05 level) of the diversity of , and S. R. Gnilka. 1975. Plankton invest- igations at Lake Sangchris 4 September 1974 zooplankton populations in the intake through 17 August 1975. Pages 2.1-2.68 in and discharge canals. Annual report for fiscal year 1975. Lake Sangchris project. Illinois Natural History' The standing crop of zooplankters in Survey, Urbana. Lake Sangchris was highest during winter of .\merican Brooks, J. L. 1957. Systematics North and early spring, decreasing through late Daphnia. Connecticut Academy of Arts and spring and summer. Sciences Memoirs 13:1-180. . 1959. Cladocera. Pages 587 656 in W.T. The calorific values of Lake Sangchris Edmondson, ed.. Ward and Whipple's fresh- littoral zooplankton crops were well water biology. 2nd ed. John Wiley and Sons. Inc., New York. within or above the range of open-lake CouTANT, L. W. 1979. .Algal dynamics of Lake values (0.+-0.6 kcal but in late m~3) Sangchris and Lake Shelby\ille. Pages 8-1-8-55 autumn and winter, littoral production in Evaluation of a cooling lake fisherv'. \ol. 4. decreased to levels below those in all prepared by Illinois Natural History Survey for Aug. 1981 Waite: Zooplankton 357 Electric Power Research Institute, Palo Alto, the United States. Ronald Press Co., Inc., New CA. York. Davies, R.M., C. H. Hanson, and L, D. Jensen. Sherstyuk, V. V. 1971. Calorific value of food 1976. Entrainment of estuarine zooplankton in a organisms in the Kremenchug Reservoir. mid- Atlantic power plant: delayed effects. Hydrobiological Journal 7 (6):85-88. Pages 349-357 in G. Esch R. W. and W. Tranqlulli, J. A., R. Kocher. and J. M, McFarlane, eds.. Thermal ecology, ERDA McNuRNEY. 1981. Population dynamics of the Syposium Series (CONF-750425), Augusta, GA. Lake Sangchris fishery. Pages 413-499 in R. W. Edmondson, W. T. 1959. Rotifera. Pages 420-494 Larimore and J. A. Tranquilli, eds.. The Lake in W. T. Edmondson, ed.. Ward and Whipple's Sangchris study: case history of an Illinois fresh-water biology. 2nd ed. John Wiley and cooling lake. Illinois Natural History Survey Sons, Inc., New York. Bulletin 32(4). Gibbons, J. W. 1976. Thermal alteration and the Waite, S. W. 1976. Filter-feeding dynamics of two enhancement of species populations. Pages Kansas cladocerans. Emporia State Research 27-31 in G. W. Esch and R. W. McFarlane, Studies 25(2): 1-28. Emporia Kansas State eds.. Thermal ecology, ERDA Syposium Series University, Emporia, KS. (CONF-750425), Augusta, GA. Wetzel, R. G. 1975. Limnology. W. B. Saunders Goulden, C. E. 1968. The systematics and Co., Philadelphia. evolution of the Moinidae. American WiLHM, J. L. and T. C. Dorris. 1968. Biological Philosophical Society Transactions 58(6):1-I01. parameters for water quality criteria. Bioscience Harleman, D., G. Jirka, and K. Stolzenbach with 18:477-481. P. Ryan and E. Adams. 1976. Heat disposal in Wilson, M. S. 1959. Free-living Copepoda: the water envirorunent. Massachusetts Institute Calanoida. Pages 788-794 inW. T. Edmondson, of Technology Press. ed.. Ward and Whipple's fresh-water biology. Survival Sons, Inc., Kedl. R. J., and C. C. Coutant. 1976. of 2nd ed. John Wiley and New York. juvenile fishes receiving thermal and mechanical , and H. C. Yeatman. 1959. Free-living stresses in simulated power plant condenser. Copepoda: Harpacticoida. Pages 815-861 in W. Pages 394-400 in G. W. Esch and R. W. T. Edmondson, ed., Ward and Whipple's fresh- McFarlane, eds.. Thermal ecology, ERDA water biology. 2nd ed. John Wiley and Sons, Syposium Series (CONF-750425), Augusta, GA. Inc., New York. KiTTiTsiNA, L. A. 1973. Effect of hot effluent from WiNBERc, G. G. 1971. Methods for the estimation thermal and nuclear power plants on of production of aquatic animals. Academic invertebrates in cooling ponds. Hydrobiological Press, New York. Journal 9 (5):67-75. Yeatman, H. C. 1959. Free-living Copepoda: Patten, B. C. 1962. Species diversity in net Cyclopoida. Pages 795-815 in W. T. phytoplankton of Raritan Bay. Journal of Edmondson, ed.. Ward and Whipple's fresh- Marine Research 20:57-75. water biology. 2rid ed. John Wiley and Sons, Penna-k, R. W. 1953. Fresh-water invertebrates of Inc., New York. The Benthic Macroinvertebrates from the Cooling Lake of a Coal-Fired Electric Generating Station Donald W. Webb ABSTRACT transition zone from hardpan clay and sand to silt. Artificial substrate samplers The benthic macroinvertebrate indicated that increased water Sangchris community of Lake was temperatures in the discharge channel examined to determine the effect of were not a limiting factor and that coal-fired electric heated effluent from a macroinvertebrates would colonize that power plant on its distribution and area if a suitable substrate were present. abundance. Of the 23 taxa of macroinvertebrates collected, chaoborids and chironomids made up 98 percent of INTRODUCTION the total. The species composition in The benthic macroinvertebrate Lake Sangchris was similar to that of community of Lake Sangchris was nearby Otter Lake although the latter examined from September 1973 to had more oligochaetes. A significantly September 1976 to determine the effect higher abundance of benthic macroin- of the heated effluent from a coal-fired vertebrates occurred in the deep water electric power plant on the species near the dam than elsewhere in the lake diversity and temporal and spatial because of the large numbers of distribution of macroinvertebrates Chaoborus punctipennis found at that relative to the various thermal regimes in station. Significantly lower levels of the lake. abundance were found in the discharge channel than at other stations because Lake Sangchris is on the boundarv- of silicate slag covered the bottom. The Sangamon and Christian counties in abundance of benthic macroin- central Illinois. It is an artificial vertebrates in Lake Sangchris was impoundment developed by damming comparable with or significantly higher three branches of Clear Creek, a than those in Otter Lake and in the tributary of the South Fork of the profundal zones of Lake Shelbyville, Sangamon River. The lake consists of Carlyle Lake, Peoria Lake, and Lake three long, narrow arms (Fig. 1 ) generally Wawasee. The abundance of benthic oriented in a north-south direction. The macroinvertebrates in the heated area of lake covers an area of 876 ha (2,165 Lake Sangchris indicated that they acres) with an average depth of 4.6 m readily tolerated the increased water (15.0 feet) and a maximum depth of 13.7 temperatures, and the seasonal biomass m (44.9 feet) at the normal elevation of closely followed the pattern for the 178.3 m (585 feet) above mean sea level. seasonal abundance. The dominant Lake Sangchris lies on the Jacksonville benthic macroinvertebrates in Lake till of the Illinoian Stage of glacial Sangchris aggregated in the deeper deposits (Johnson 1964). Core samples portions of the lake where a silt substrate (Limnetics, Inc. 1972) showed the surface was present, and the greatest diversity sediments to be dark gray clay and silty occurred between 4 and 6 m, the clay with fine-grained sand and organic fibers. The lake bottom from the Donald W. Webb is an Associate Taxonomist. shoreline to a depth of 4 was generally Section of Faunistic Surveys and Insect m Identification, Illinois Natural History Survey. hardpan clay with isolated areas of sand This chapter submitted in March 1978. and fine gravel. Below 4 m the lake 358 Aug. 1981 Webb: Benthic Macroinvertebrates 359 bottom consisted of fine silt with Branch (1.6 km north of Zenobia) of allochthonous organic detritus. The Clear Creek above the impounded waters bottom sediment in the discharge of Lake Sangchris to gain insight into the channel from the power plant was probable composition of the stream covered with a layer of silicate slag. fauna prior to the stream's impoundment. For purposes of comparison with a lake not receiving heated effluent, the MATERIALS AND METHODS benthic community of Otter Lake was examined from April through November The average biweekly bottom 1975 and from April through September temperature and oxygen concentration 1976. Otter Lake is a water supply for the heated, or discharge arm, reservoir 9.7 km (6 miles) west of Girard, (stations 5, 4, and 3) and unhealed or Macoupin County, Illinois, and lies on intake- and control-arm, areas (stations 2, the same sediment topography as Lake 1, and 7) of Lake Sangchris from 1973 Sangchris. through 1976 have been extracted from Benthic samples also were collected data collected by Brigham (1977). during 1974 and 1975 in the East Branch Monthly benthic collections in Lake (6.1 km south of Bulpitt) and the West Sangchris began on 19 September 1973 DISCHARGE POWER CHANNEL PLANT macroinvertebrates. Fig. 1 — Lake Sangchris sampling stations for benthic 360 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 and continued through 3 September natural logarithm of the total number of 1976. Collections were made at six individuals (N): midchannel (profundal) sites (Fig. 1). = Three 15.2- x 15.2-cm (6- x 6-inch) d s-1 Ekman grab samples were taken at each InN station and at a depth of 2 m at both shoreline at stations 2, 3, 4, and 7. The To determine the spatial distribution selection of three samples at each site was of benthic macroinvertebrates, 12 based on species averaging for one transects were selected (Fig. 2). At each standard deviation from a mean of 30 transect three Ekman grab samples were samples that had been collected for collected at the shoreline and then at statistical analysis. Samples were washed every 2 m in depth across the transect to through a brass screen (no. 30 mesh), the opposite shore. A total of 288 samples preserved in 70-percent ethyl alcohol, was taken at 96 sites during collecting and sorted in white enamel pans. At each periods in May, July, and September of station, species diversity (d) was 1974 and May and July of 1975. determined by the equation of Margalef Comparisons were made among different (1958), which expresses the relationship transect locations, depths, substrates, between the number of species (s) and the months, and water temperatures. DAM OQ LAKE SANGCHRIS 1,61 KM (1 mile) INTAKE DISCHARGE CHANNEL' CHANNEL cy POWER o PLANT Fig 2. — Lake Sangchris sampling transects for spatial distribution of benthic macroinvertebrates. Aug. 1981 Webb: Benthic Macroinvertebrates 361 In viewing the distribution pattern of in June, August, and October. The benthic macroinvertebrates within Lake artificial substrate samplers were Sangchris, the samphng efficiency of the constructed from half of a minnow trap Ekman grab on hardpan clay and sand with an aluminum pan sealing each end. must be taken into consideration. For Each sampler contained four 7.6- x 7.6- x samples taken along the shoreline the 7.6-cm (3- X 3- X 3-inch) cement blocks, ~ jaws of the grab were closed by hand to with a surface area of 1 ,386 cm 2 placed ensure that the surface area enclosed by on edge. Only specimens from the bottom the grab was scraped clean. In taking pan and six sides of the four cement samples from depths of 2-4 m, only those blocks, having a total area of 1,796.7 samples in which the jaws of the grab cm^-^, were collected. were completely closed were retained for In Otter Lake, benthic collections sorting and counting. were taken monthly from 16 April The effect of heated effluent and through 18 November 1975 and from 19 bottom substrate on benthic April through 3 September 1976. Three macroinvertebrates in the discharge Ekman grab samples were collected at channel (Station 5) was compared to that each of six sites (Fig. 3) in the northern in the intake channel (Station 1) by half of Otter Lake. The depth at these taking three artificial substrate samples sites ranged from 1 to 8 m, with stations 1 at each station, beginning in April 1975, to 5 in the littoral-sublittoral zone and ,and collecting the colonizing organisms Station 6 in the profundal zone. OTTER LAKE (northern half) Fig 3—Otter Lake ampling stations for benthic nacroinvertebrates. 362 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Artificial substrate sampler used in benthic studies at Lake Sangctiris. Data were analyzed by one-way temperatures were at Station 4 and analysis of variance and the Kramer Station 3, considered a transition zone (1956) extension of Duncan's multiple between the heated and unheated areas range test. Comparisons were made at the and included in the heated area because 0.05 level of significance. it was affected by the thermal effluent. Differences in the average bottom RESULTS AND DISCUSSION temperatures between the heated and unheated areas generally ranged from 4" WATER TEMPERATURE AND to 8° C through the spring, summer, and OXYGEN CONTENT autumn and between 8° and 12° C during the winter months. Bottom temperatures Because both water temperature and in Otter Lake followed the general oxygen concentration can limit the pattern observed for Lake Sangchris. growth, distribution, and abundance of benthic macroinvertebrates, the seasonal Oxygen concentrations generally variation of those parameters in Lake ranged higher in the unheated area of Sangchris are presented (Fig. 4 and 5) for Lake Sangchris from 1973 through 1976 reference to the distribution and than in the heated area (Fig. 5), but abundance of benthic organisms. the discharge channel consistently had Bottom temperatures in Lake the highest levels of oxygen (except for Sangchris were highest in the discharge the winter of 1973-1974). The higher channel (Station 5), ranging from 25" to oxygen concentrations in the discharge 40" C during the summer and 10»-15° C channel were due to enhanced during the winter. The next highest atmospheric reaeration resulting from — Aug. 1981 Webb: Benthic Macroinvertebrates 363 = STATIONS 5, H, 3 (discharge arm) -• = STATIONS 2, Ij 1 (intake AND CONTROL ARMS) -^^^— = OTTER LAKE 30-1 '_ 20- S= 10 T SEPT, JAN, MAY SEPT, JAN, MAY SEPT, I | | JAN, MAY SEPT, I | | I NOV, MAR, JUL, NOV, MAR, JUL, NOV, MAR. JUL, 1973 1974 1975 1976 Fig. 4. —Average bottom temperatures in the discharge and the intake and control arms of Lake Sangchris from 1973 through 1976 and in Otter Lake during 1975 and 1976. •=STATIONS 5., 4, 3 (discharge ARM ) • •= STATIONS 1, \, 1 (INTAKE AND CONTROL ARMs) 15-1 10 5 "1 1 '—\ 1 1 1 1 \ 1 SEPT, JAN, MAY | SEPT, JAN, | MAY | SEPT, JAN, | MAY | SEPT. | | I I NOV, MAR, JUL, NOV, MAR. JUL, NOV, MAR, JUL. 1973 1974 1975 1975 Fig. 5. —Average oxygen concentrations in the discharge and the intake and control arms of Lake Sangchris from 1973 through 1976. the high turbulence as the heated effluent all organisms collected, and the was expelled from the power plant. nonbiting midges (Chironomidae) 39 Oxygen concentrations in Otter Lake for percent. Within the Chironomidae, six ,1975 (April through November) and 1976 species (Chironomus attenuatus, (April through September) ranged from Cryptochironomus fulvus, Coelotanypus 3.4 to 9.6 mg/1 at a depth of 8 m, which conctnnus, Glyptotendipes lobiferus, was comparable to those at Station 2 in Procladius bellus, Xenochironomus the unhealed area of Lake Sangchris. festivus) of the 15 collected represented 94 percent of the chironomids collected. TAXA COLLECTED Other benthic macroinvertebrates, such Twenty-three taxa of oligochaetes, as mayflies, caddisflies, and oligochaetes, decapods, mollusks, and insects were represented only 2 percent of the collected in Lake Sangchris (Table 1). organisms collected. The phantom midge (Chaoborus Benthic macroinvertebrates (Table 1) punctipennis) represented 59 percent of in the headwaters of the East and West : I 364 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 branches of Clear Creek above the in the impounded habitat. Forty-one taxa impounded waters of Lake Sangchris were collected, including the major taxa exhibited greater diversity than did those occurring in Lake Sanghcris. The greater X X X X X X X X X X X X X X X X X X X X X X X X X ^ X X X X X X X X X X X X X X li c X XX XX X xxxxxx X X XXX XXX XXX X XXX XXXX X X X xxxxxx X X X X X X xxxxxx X X X X xxxxxx X X xxxxxx xxxxxx |3 3 J :5 D. K a 3 § . 5= 3 I5" a 3 tic a 2 ^ a o .« ?> d. . ill -2 ^ "Cm lo *' .*; E J 3 ^1 V. .S 1/1 (^ *^ 1— ^n> "13-M ^ IT" E £ g S-SS c ^1 S E -? m I' £««,&£« S .2 0k;"o"^«.~w I 2 go o oQ a; -g (J 3; (J < X U I Aug. 1981 Webb; Benthic Macroinvertebrates 365 diversity was due primarily to the gfreater insects (Table 1) were collected from diversification of habitat. Otter Lake, all of which were collected in Eighteen taxa of oligochaetes and Lake Sangchris. The oligochaete, ?< X X X XXX XXX XX XX XXX X XX X X X X XXXXX XXXX XXXXXXX XX u 2 C o CO n XXX X X XXX XXXXX XXX XX X X XXXX XXX XXXX X XXXX XX X XX XX a. 3 eg 3 -a E o C ^S 3 S i S 5r=3 .a 8 . 3 - 2 3.- -^ 3 .£ : Z a, a. O. I ,.3 - " 3 I - " 31- „-- 1^ I" >J aj •»» « 3rJ t"J tn " ^ -is - ^ n •&. &-O ? ? 5: =! .- .^.-S Egg ao S ct oJ3 k-Q.« 3ii 5 a^-o,a 5 5 c5,° *-§,"= ?>,-i — Xu S Vol. 32, Art. 4 366 Illinois Natural History Survey Bulletin for more Limnodrilus hoffmetsteri (18 percent), chironomids, which accounted the benthic the phantom midge, Chaoborus than 80 percent of punctipennis (40 percent), and the macroinvertebrates. macroinverte- nonbiting midges (Chironomidae) (39 The wide variety of Indiana lakes was percent) made up 97 percent of the total brates in northern Illinois River organisms collected from Otter Lake. similar to that collected in (Wohlschlag 1950) Oligochaetes were distinctly more lakes. In Wabee Lake macroinvertebrates were abundant in Otter Lake than in Lake benthic narrow littoral zone Sangchris. restricted to a because a marl substrate covered much of Initially, Limnetics, Inc., (1972) the lake bottom. In Lake Wawasee benthos in Lake reported a paucity of (Scott, Hile, & Spieth 1928) 22 taxa were Sangchris, but in a supplemental study collected, with the diversity of (Limnetics, Inc. 1973) collected 24 taxa. macroinvertebrates extending well into studied three Paloumpis & Starrett (1960) the profundal zone (9-15 m). lakes of the Illinois River near floodplain The diversity of macroinvertebrates in composition Havana. The species Lake Sangchris appears normal when Diptera larvae consisted of compared with those of other central = Procladius, {Pelopia Tanypus, Illinois lakes (Otter Lake, Lake Chaoborus), oligochaetes, Coelotanypus, Shelbyville, Carlyle Lake) although it mayflies (Hexagenia limbata), sphaeriid lacks the variety of clams, isopods, The benthic clams, and leeches. amphipods, and leeches prevalent in communities varied markedly from lake Illinois River and northern Indiana lakes. to lake although oligochaetes constituted The littoral zone of Lake Sangchris, , percent of the fauna in each of over 60 outside of the coves, consists primarily of on Illinois River lakes the lakes. Studies hardpan clay and sand with scattered 1921a, 19216, 1924, 1925, (Richardson areas of macrophytes, a habitat which indicated that oligochaetes and 1928) may account for the absence of certain and clams were the dominant macroinvertebrates there. , macroinvertebrates although a variety of leeches, chironomids, snails, amphipods, isopods, caddisflies, mayflies, odonates, SEASONAL ABUNDANCE Most of these and sialids were present. The seasonal abundances of benthic the wide organisms were distributed in macroinvertebrates at midchannel of the lakes, away from the main portions (profundal) sites in Lake Sangchris from of Clearwater river channel. A study 1973 through 1976 are shown in Fig. 6. In (O'Connell & Campbell Lake, Missouri, the discharge channel (Station 5) benthic of taxa 1953) showed that a wide variety macroinvertebrates ranged in abundance newly formed reservoirs. ~ inhabits from to 244 organisms m 2. Although Culicidae (probably Oligochaetes, the highest bottom temperatures and Chironomidae Chaoboridae), and oxygen concentrations were in the of the fauna, and constituted 90 percent discharge channel, the silicate slag than taxa at no time were fewer 13 covering the bottom provided an littoral zone during any collected in the unsuitable habitat for the animals. sampling period. Artificial substrate samples at that station that benthic Annual reports to the Army Corps of (Table 4) indicated would colonize a Engineers for Lake Shelbyville (Brigham macroinvertebrates areas of high water 1973, 1974, 1975, and 1976) and Carlyle suitable substrate in exception of those Lake (Dufford, Swadener, & Waite 1976 temperature. With the discharge channel, and 1977) indicated that the diversity of taken from the collected benthic organisms was greatest at lotic benthic macroinvertebrates loop of the lake (stations stations. The lentic stations in these from the cooling 57 to 5,028 organisms m-2, central Illinois reservoirs were dominated 4, 3, 2, and 1) of by chaoborids, oligochaetes, and equal to or greater than the levels Aug. 1981 Webb: Benthic Macroinvertebrates 367 STATION 'i -»= STATION 5 Fig, 6. — Seasonal abun- dances of benthic microin- vertebrates in Lake Sangchris fronn 1973 through 1976. I I I I I n 1 1 I I I I I I I SEPT.' JAN.' MAY 'sEPT,' JAN.' MAY 'sEPT.' JAN.' MAY ' SEPT NOV, MAR. JUL. NOV, MAR, JUL. NOV. MAR. JUL. 1973 1974 1975 1975 ~ abundance (86-4,735 organisms m '^) macroinvertebrates in Lake Sangchris found in the control arm (Station 7). The was in phase with those of Illinois lakes seasonal abundance of benthic that receive no heated effluent. 2500- STATIONS S, ^, 3 (discharge arm) : STATIONS 2, 1, 1 (intake and control arms) t\ 2000- • OTTER LAKE ^ n CM I \ I \ \ o 1500- I \ 1000- 500- I I I JAN, I MAY I SEPT. SEPT, JAN, I hAY I SEPT, JAN, MAY SEPT. | NOV. MAR. JUL, MAR, JUL. NOV. MAR, JUL. 1973 1974 1975 1976 Fig. 7. —Average seasonal abundances of benthic macroinvertebrates in the discharge arm (heated) and intake and control arms (unhealed) of Lake Sangchris from 1973 through 1976 and in Otter Lake during 1975 and 1976. 368 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 I The average abundance of benthic abundance. The mean abundance of macroinvertebrates (Fig. 7) was higher in macroinvertebrates was significantly the discharge (heated) arm (stations 5, 4, (0.05 level) lower at Station 5 in the and 3) of Lake Sangchris from September discharge channel than at any other 1973 through March 1974 and then station. closely paralleled the abundance in the In Otter Lake during both 1975 and intake and control arms (stations 2, 1, 1976, Station 6 in the profundal zone was and 7) through the rest of the year. significantly higher in the abundance of Through 1975 and 1976, the average macroinvertebrates (0.05 level) than were abundance fluctuated considerably, stations 1 through 5 in the littoral- particularly in the intake and control sublittoral zone (Table 2). arms, with the average abundance From April through November 1975, generally higher there than in the the abundances of macroinvertebrates at discharge arm. The average abundance stations 3, 4, and 7 in Lake Sangchris for the entire lake during this study were comparable to that at Station 6 in ~ ^ ranged from 250 to 2,000 organisms m Otter Lake (Table 2). During April and was, with one exception, always through September 1976, the above the levels of abundance observed abundances of macroinvertebrates at for Otter Lake. stations 3, 1, 7, and 2 in Lake Sangchris Analyses of variance of the mean were comparable to that at Station 6 in numbers of benthic macroinvertebrates Otter Lake (Table 2). During both at each profundal station in Lake periods the numbers in the discharge Sangchris demonstrated that they were channel (Station 5) of Lake Sangchris sigfnificantly more abundant (0.05 level) were comparable to those of the littoral- at Station 3 than at any other station sublittoral stations of Otter Lake. (Table 2). Stations 2, 7, 4, and 1 (in rank A comparison of the profundal order of decreasing means) formed a stations of Lake Sangchris. Lake subset having an intermediate level of Shelbyville (Brigham 1973, 1974, 1975, Table 2 —Comparison of the analyses of variance of tfie means of abundance of benthic macroinvertebrates at each profundal station in Lake Sangchris (Sa); in Otter Lake (Ot): and in the profundal zones of Lake Shelbyville (Sh), Carlyle Lake (Ca), and Lake Wawasee (Wa), Indiana (005 level of confidence). Each underlined value Is comparable to values with the same underline and is significantly higher than the other values to its right. Lake Sangchris Profundal Stations Station 3 2 7 4 15 Mean 1,688 1.117 985 920 818 40 Otter Lake 1975 (April to November) Station 6 2 4 5 3 1 Mean 61 23 15 12 12 10 Otter Lake 1976 (April to September) Station 6 15 3 4 2 Mean 84 27 21 21 13 13 Lake Sangchris (Sa) Otter Lake (Ot) 1975 (April to November) Station 3(Sa) 4(Sa) 7(Sa) 6(Ot) 2(Sa) l(Sa) 2(Ot) 4(Ot) 5(Ot) 3(Ot) l(Ot) 5(Sa) Mean 101 66 62 61 55 51 23 15 12 12 10 3 Lake Sangchris (Sa) Otter Lake (Ot) 1976 (April to September) Station 3(Sa) 6(Ot) l(Sa) 7(Sa) 2(Sa) 4(Sa) l(Ot) 5(Ot) 3(Ot) 4(Ot) 2(Ot) 5(Sa) Mean 118 84 83 74 68 47 27 21 21 13 13 2 Lake Sangchris (Sa) Lake Shelbyville (Sh) Carlyle Lake (Ca) Lake Wawasee (Wa) Station 3(Sa) (Sh) 2(Sa) (Ca) 7(Sa) 4(Sa) (Wa) l(Sa) 5(Sa) Mean 1,688 1,209 1.117 1.114 985 920 890 818 40 Aug. 1981 Webb: Benthic Macroinvertebrates 369 and 1976), Carlyle Lake (Dufford, discharge channel, where the presence of Swadener, & Waite 1976 and 1977), and slag covering the bottom apparently Lake Wawasee, Indiana (Scott, Hile, & limits the colonization by benthic Spieth 1928) (Table 2) showed that the macroinvertebrates, the abundance of aisundance of macroinvertebrates at such organisms in the cooling loop of Station 3 in Lake Sangchris and in the Lake Sangchris is comparable to or profundal zone of Lake Shelbyville were significantly higher than the abundance comparable and significantly higher at Station 7 in the control arm and the (0.05 level) than those at stations 2, 7, 4, abundance in Lake Shelbyville, Carlyle Lake, Lake Wawasee, and Peoria Lake. 1 , and 5 of Lake Sangchris and of Carlyle Lake and Lake Wawasee. Macroinvert- Apparently no reduction in the ebrate abundances in Lake Shelbyville, abundance of benthic macroinvertebrates Carlyle Lake, and Lake Wawasee were has resulted from the increase in water comparable to those of stations 2, 7, 4, temperature. and 1 of Lake Sangchris. The discharge channel (Station 5) of Lake Sangchris had a significantly lower abundance ABUNDANCE OF DOMINANT (0.05 level) than the other stations in SPECIES Lake Sangchris and Lake Shelbyville, L Carlyle Lake, and Lake Wawasee. Analyses of variance of the means of I The range of abundance of benthic abundance of the dominant macroin- is I macroinvertebrates in Lake Sangchris vertebrates of Lake Sangchris showed also comparable to those in Upper, that Chaoborus punctipennis was Middle, and Lower Peoria Lake significantly more abundant (0.05 level) (Richardson 1928) in the Illinois River. in the deepest area of the lake (Station 3) During 1924 the abundance of than at any other station. Its lowest abun- macroinvertebrates in Peoria Lake varied dance occurred in the control arm (Station from 192 to 5,634 organisms m~ 2 (mean 7) and the discharge channel (Station 5) 2,252), and in 1925 from 844 to 1,684 (Table 3). organisms m~" (mean 1,530). In contrast, Paloumpis & Starrett (1960) found benthic macroinvertebrates in Table 3—Comparison of the analyses of variance of the means of abundance of the domi- Lake Matanzas, middle Quiver Lake, nant benthic macroinvertebrates from the pro- and Lake Chautauqua to vary from 1 ,959 fundal zone of Lake Sangchris (005 level of con- to 16,792 (mean 5,326), 2,680 to 43,981 fidence) Each underlined value is comparable to and is significant- (mean 11,922), and 3,767 to 17,976 values with the same underline ly higher than the other values to Its right. (mean 9,533) organisms m~ 2 respective- ly. Those lakes are broad expansions of floodplain lakes of the Illinois River and received considerable enrichment from Station waterfowl. From these data it is evident that the benthic macroinvertebrates of Lake Sangchris form three distinct subsets in terms of abundance, the deepest profundal zone (Station 3) being significantly higher in macroinvertebrate abundance; the cooling loop and control arm being intermediate and, within this subset, having comparable populations; and the discharge channel having a significantly lower abundance of macroinvertebrates than the other stations. With the exception of the 370 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 This is the typical distribution for C. (Table 3) at Station 2 in the intake arm puncttpennis in large lakes, where they than at any other station, and its lowest tend to be restricted to the deeper zones abundance was at stations 4 and 5 in the (Eggleton 1931, Juday 1921, Stahl 1966). discharge arm. This species is embenthic The mature larvae live in the mud during (Beck 1977) and considered primarily a the day and become nektonic and scavenger, feeding on nonliving plant limnetic during the night (Berg 1937, and animal material. It is also Eggleton 1931, Juday 1921), feeding on eurythermal to mesothermal (Beck 1977) copepods, oligochaetes, chironomid although lovino & Miner (1970) found it larvae, rotifers, mosquito larvae, and to be oligothermal in Beaver Reser\oir, other chaoborid larvae (Berg 1937, Arkansas. In Beaver Reservoir, lovino & Deonier 1943, Main 1953, Stahl 1966). Miner (1970) found that C. attenuatus Chaoborid larvae are especially abundant concentrated in the deepest areas of the in the deeper portions of lakes wrhere the lake. In Lake Sangchris. the aggregation hypolimnion becomes depleted of oxygen of C. attenuatus at Station 2 rather than (Thienemann 1922, Findenegg 1955). in the deepest area of the lake (Station 3) Although showing a preference for the could be the result of competition for deeper, colder zone of a lake, chaoborid space with Chaoborus puncttpennis or of larvae are extremely eurythermal, heavy predation from Chaoborus capable of migrating from 4° C to 20° C punctipennis feeding on the earlier and and back to 4° C within a day (Welch smaller instars of Chironomus 1952). attenuatus. Both possibilities are Procladius bellus and Coelotanypus conceivable, as Chaoborus punctipennis concinnus were significantly more was nearly three times more abundant at abundant (0.05 level) in the control Station 3 than Chironomus attenuatus. arm (Station 7) (Table 3) than at other The abundance of Cryptochironomus stations in the lake. Both species are fulvus was not significantly different considered predators or scavengers and among the sampling sites. Thus, each of eurythermal (Beck 1977). Roback (1969) the dominant species of macroinverte- reported both species feeding heavily on brates in Lake Sangchris tends to exhibit diatoms, as well as on oligochaetes, a distinctiveness in its abundance with cladocerans, and other chironomid respect to its interrelationships which larvae. The level of phytoplankton other species and with the physical , photosynthesis in the control arm (Station conditions of the lake. I 7) was higher than it was at other stations (R.L. Moran, Illinois Natural SEASONAL VARIATIONS IN History Survey, personal communication) BIOMASS although the abundance of benthic macroinvertebra tes • there was The seasonal variations in the average comparable to that of the cooling loop in biomass (wet weight) of benthic general except at Station 3 and macroinvertebrates for the heated and significantly below the abundance of unheated arms of Lake Sangchris from macromvertebrates in the intake arm. 1973 through 1976 and in Otter Lake for There was no evidence that fish 1975 (April through November) and 1976 predation on benthic macroinvertebrates (April through September) are shown in was concentrated in the control arm as Fig. 8. The variations in biomass compared with such predation at other generally followed the pattern for the stations in the lake. These data suggest seasonal level of abundance (Fig. 7). The that Procladius bellus and Coelotanypus biomass in the discharge (heated) arm concinnus may have been seeking the ranged from 0.11 to 2.30 g m~2 2s\A was area of greatest growth or abundance of quite similar to that of the intake and phytoplankton. control arms (0.04-1.47 g m-2)(Fig.8), Chironomus attenuatus was indicating that increased water significantly more abundant (0.05 level) temperatures did not limit the growth of I I Aug. 1981 Webb: Benthic Macroinvertebrates 371 2.5-, •= STATIONS S, ^, 3 (discharge arm) = STATIONS 2j 1^ 7 (intake and control arms) 2.0- .— OTTER LAKE 1.5- 1.0- 0.5- -I 1 1 r 1 — — I NAY SEPT. SEPT. JAN. | SEPT. JAN. MAY SEPT, JAN. MAY | NOV. MAR. JUL. NOV. tIAR. JUL. NOV, MAR. JUL. 1973 1971) 1975 1976 macroinvertebrates in the Fjg. 8 —Average seasonal distribution of the standing crop of benthic discharge arm (heated) and the intal benthic macroinvertebrates in the heated BATHYMETRIC DISTRIBUTION arm of the lake. The small numbers of benthic macroinvertebrates in the The bathymetric distribution of discharge channel reduced the average benthic macroinvertebrates in Lake values for biomass in the heated portion Sangchris during 1974 and 1975 of the lake. With two exceptions, the indicated that their greatest abundance biomass values in the heated and (Fig. 9) occurred at depths of 4 m or more unheated parts of Lake Sangchris were where the bottom sediments were higher than the levels for Otter Lake, composed primarily of silt. The bottom which ranged from 0.06 to 0.38 g~^ sediments from the shoreline to a depth during the summer of 1975 and 0.15 to of 4 m contained large areas of hardpan 0.37 g m~ 2 during the summer of 1976. clay and sand, in addition to the layer of In Carlyle Lake (Dufford, Swadener, & slag which covered the bottom of the Waite 1977) the lentic biomass ranged discharge channel, all of which are from 0.15 to 5.64 g m~2 and for the unsuitable as habitats for most benthic floodplain lakes of the Illinois River organisms. Xenochironomus festivus, (Paloumpis & Starrett 1960) the average Glyptotendipes lobiferus, and Cricotopus biomass in Lake Matanzas, middle bicinctus, which is epiphytic (Beck 1977), Quiver Lake, and Lake Chautauqua was were collected only in the littoral and 9.69, 47.79, and 16.15 g m-2, respectively. sublittoral zones from to 4 m. Both The high average biomass of benthic Procladius bellus and Coelotanypus macroinvertebrates in the floodplain concinnus, which are eurythermal and lakes compared to that of Lake Sangchris predaceous or scavengers (Beck 1977), all depths of is due to the larger biomass of fingernail were distributed throughout clams collected. The biomass in Lake the lake. Chaoborus punctipennis and is Sangchris falls within the range of those Chironomus attenuatus, which generally found in other central Illinois lakes (Otter embenthic (Beck 1977), were Lake, Carlyle Lake). collected only in the profundal zone. 1 372 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 4-! 6-^ 400 1 400 400 I I 400 I 200 200 600 200 200 600 1000 200 500 MAY 1974 JULY 1974 SEPT. 1974 MAY 1975 JULY 1975 AVERAGE NUMBER PER SQUARE METER Fig. 9. — Bathymetric distribution of benthic macroinvertebrates in Lake Sangchris during 1974 and 1975. SPATIAL DISTRIBUTION macroinvertebrates in the littoral zone ~ averaged below 200 organism m 2 (pig g). When large numbers of chironomid The spatial distribution of benthic larvae (Cricotopus bicinctus) were macroinvertebrates in Lake Sangchris collected along the shoreline, they were during 1974 is shown in Fig. 10. The flow associated with a layer of algae covering of heated effluent moves from transect 1 the hardpan clay. The low abundance of in the discharge channel (Fig. 2) to macroinvertebrates collected during May transect 1 in the intake arm, with transect can be attributed to the emergence of 12 in the control arm of the lake aquatic insects at that period of the year. unaffected by the thermal discharge. In Larvae hatching from deposited eggs May, July, and September, the general would account for the increase in abundance of benthic macroin- abundance during July and September. vertebrates increased in numbers from Depth distributions of benthic transect 11 in the discharge channel macroinvertebrates have not been to transect 3 in the intake arm and then reported for other Illinois lakes although decreased moderately toward the intake in Lake Wawasee, Indiana (Scott, Hile, area. Across each transect the abundance & Spieth 1928) benthic macroinverte- of macroinvertebrates increased with brates were collected abundantly to the depth, the greatest abundance occurring deepest portions of the lake, reaching generally in the deepest portions of each over 1,000 organisms m ~ " at depths of transect. On some occasions high 3, 11, 13, 15, and 17 m. The bottom concentrations of benthic macroin- sediments in Lake Wawasee consisted of vertebrates (reaching 2,500-3,000 fine silt at depths of 3-23 m. indicating organisms m~2) were collected that silt provides a suitable substrate for immediately along the shoreline (Fig. 10) the growth and development of benthic although generally the abundance of macroinvertebrates. Aug. 1981 Webb: Benthic Macroinvertebrates 373 1000 -| MAY 1971 I JULY 1971 DEPTH (H) °^r T^^° T^T T^mr "f6"l0 12 1 2 3 9 10 11 TRANSECT Fig. 10. —Spatial distribution of benthic macroinvertebrates in Lake Sangchris during May, July, and September 1974 = MAY, 1974 -O = MAY, 1975 = JULY, 1974 - = JULY, 1975 • • = SEPT., 1974 DEPTH (Fl) Fig. 11.—Average species diversity at various depths of benthic macroinvertebrates in Lake Sangchris during 1974 and 1975, 374 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 SPECIES DIVERSITY BY DEPTH three artificial substrate samplers were placed in both the discharge channel All values for species diversity across (Station 5) and the intake channel the 12 transects were averaged for each (Station 1) during 1975. The abundance depth for collections taken in May, July, and diversity of organisms collected from and September 1974 and and May July the samplers during June, August, and 1975. Fig. 11 shows the greatest diversity October are shown in Table 4. 4-6 occuring at m, the transition zone Macroinvertebrates were most abundant from hardpan clay and sand to silt. in the intake channel (Station 1) during August and October. The lower numbers observed in June could be attributed to the emergence of adult insects from the EFFECTS OF WATER lake during this period. A high degree of TEMPERATURE AND species diversity was observed during each BOTTOM TYPE period. At the discharge channel (Station 5) the abundance of organisms collected To determine if increased water was relatively low, ranging from 180 to temperatures or the presence of silicate 407 organisms m " 2 corripared with slag caused the severe paucity of benthos 244-800 organisms m~2 for Station 1. in the discharge channel (Station 5), During June and August the species Table 4. — Benthic organisms collected from artificial substrate samplers in tfie intake cfiannel and discfiarge channel of Lake Sangchris during 1975. The numbers shown were taken from three substrate samplers unless otherwise noted. Intake Channel Discharge Channel Species (Slation 1) (Staiion 5) Aug. 1981 Webb: Benthic Macroinvertebrates 375 diversity was low but showed an increase only prolonged periods of high water during October. When the abundance of temperatures would restrict the diversity macroinvertebrates at Station 5 was of benthic macroinvertebrates. compared with the numbers collected during standard Ekman grab sampling SUMMARY (Fig. 6), it was evident that the increased water temperature in the discharge 1. —Twenty- three taxa of benthic channel was not the principal factor macroinvertebrates were collected in limiting the presence of benthic Lake Sangchris, with chaoborids (59 macroinvertebrates, but rather the percent) and chironomids (39 percent) presence of an unstable silicate slag representing 98 percent of the total covering the bottom sediments. numbers. The diversity of benthic Organisms colonized in this channel macroinvertebrates in Lake Sangchris is central when a suitable substrate was provided. consistent with those of other Illinois lakes (Otter Lake, Lake Massengill (1976) found that benthic Shelbyville, Carlyle Lake) although it macroinvertebrates in the discharge lacks the variety of clams, isopods, channel from a nuclear power plant on amphipods, and leeches prevalent in the Connecticut River ranged from to Illinois River and northern Indiana lakes. 900 organisms m~2 and generally fewer benthic than 200 organisms m ~ 2 were collected 2. — Eighteen taxa of during most of the year. With water macroinvertebrates -were collected in temperatures of 37° C, Limnodrilus Otter Lake, with chaoborids (40 percent), and hoffmeisteri was the only species of percent), chironomids (39 macroinvertebrate present during July, oligochaetes (18 percent) representing 97 total numbers, the major reaching 900 organisms m^ '^. Four days percent of the as those in Lake later at temperatures of about 40° C, the species being the same abundance of L. hoffmeisteri dropped to Sangchris. 30 organisms m~2 The maximum 3.— The abundance of benthic could tolerate temperature this organism macroinvertebrates in Lake Sangchris ' appeared to be slightly above 37° C. shows three distinct subsets: it was significantly higher in the deepest areas; The bottom sediment in the discharge intermediate in the cooling loop and channel was predominately silt, and the control arm, where there were average velocity in the channel varied comparable populations; and from' 0.3 to 0.6 m/sec, diminishing to 6 significantly lower in the discharge cm/sec at the mouth. During February, channel than elsewhere in the lake. April, and June, when average temperatures were 11°, 14°, and 22° C, 4.— The abundance of Chaoborus respectively, the abundance of benthic punctipennis (59 percent of the total macroinvertebrates was less than 200 numbers of macroinvertebrates) was organisms m^2 Ybe highest abundance greatest in the deepest areas of the lake. of macroinvertebrates occurred at The significantly low abundance of temperatures of 37° C during July. macroinvertebrates in the discharge channel was due to the silicate slag Massengill presented no reasons for covering the bottom and providing an the of macroinvertebrates in the I paucity unsuitable substrate for colonization. ' discharge channel except at temperatures over 37° C during the summer. During 5. — With the exception of the of the remainder of the year, bottom discharge channel, the abundance temperatures were not excessive and benthic macroinvertebrates in the cooling comparable considerable silt habitat was present. At loop of Lake Sangchris was no time was the channel velocity high with or significantly higher than those in and in the enough to remove the silt from the the control arm (Station 7) Carlyle Lake, Lake channel. From this study it is evident that Lake Shelbyville, 376 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Wawasee, and Peoria Lake, and showed that the bottom provided an unsuitable no detrimental effects from the increase substrate for benthic colonization. in water temperature. REFERENCES 6. — Chaoborus punctipennts was CITED significantly more abundant in the Beck. W. M.. Jr. 1977. Environmental require- ments and pollution tolerance of common fresh- deepest warer, Procladius bellus and water Chironomidae . Environmental Coelotanypus concinnus were Monitoring Series. EPA - 600/4 - 77 - 024. significantly more abundant in the Environmental Monitoring and Support control arm, and Chironomus attenuatus Laboratory. USEPA. Cincinnati. 261 p. was significantly more abundant in the Berg. K. 1937. Contributions to the biology of Corethra Meigen (Chaoborus Lichtenstein). intake arm than at the other stations in Danske Videnskabernes Selskab. Biologiske Lake Sangchris. Cryptochironomus Meddelelser 13. Levin & Munksgaard. fulvus was ubiquitous in its distribution. Copenhagen. 101 p. Each dominant species exhibits a Brigham. a. R. 1973. Water quality investigation distinctiveness in its abundance with in the Lake Shelbyville. Illinois basin. Annual report submitted to the U. S. Army Corps of respect to its interrelationship with other Engineers. St. Louis District. 44 p. species and the physical conditions of the . 1974. Water quality investigations in the lake. Lake Shelbyville. Illinois basin. Annual report submitted to the U. S. Army Corps of Engineers. 7. — The seasonal variation in St. Louis District. 42 and appendices. biomass (wet weight) of benthic p. . 1975. Water quality investigations in the macroinvertebrates in the discharge Lake Shelbyville. Illinois basin. Annua] report (heated) arm of Lake Sangchris was quite submitted to the U. S. Army Corps of Engineers. similar to that of the intake and control St. Louis District. 23 p. and appendices. arms. Average biomass values were . 1976, Water quality investigation in the generally higher than those of Otter Lake Shelbyville, Illinois basin. Annual report Lake and comparable to those submitted to the U. S. Army Corps of Engineers. determined for Carlyle Lake, indicating St. Louis District. 41 p. that increased water temperatures in the . 1977. Water quality investigations at Lake Sangchris. Pages 1.1-1.5.18 in annual report for heated arm did not limit the growth of fiscal year 1976. Lake Sangchris project. Illinois benthic macroinvertebrates in Lake Natural History Survey. Urbana. Sangchris. Deonier. C. C. 1943. Biology of the immature 8.— The greatest abundance of stages of the Clear Lake gnat. Entomological Society of America Annals 36:383-388. benthic macroinvertebrates in Lake DuFFORD, D. W.. S. O. SwADENER. and S. W. Sangchris occurred at depths of 4 m or Waite. 1976. Annual summary of biological more where the bottom sediment was silt. investigations at Carlyle Lake 1974- 1 975. The presence of hardpan clay to a depth Annual report submitted to the U. S. Army of 2-4 m and the absence of layers of Corps of Engineers. St. Louis District. 51 p. detritus within the littoral- organic . . . and 1977. Annual sum- sublittoral zone, outside the peripheral mary of biological investigations at Carlyle Lake coves, appear to limit the habitat and 1975-1976. Annual report submitted to the U. S. Army Corps of Engineers. St. Louis District. food availability for benthic 51 p. macroinvertebrates in this zone. Eggleton, F. E. 1931. A limnological study of the 9. — The greatest species diversity of profundal bottom fauna of certain fresh-water lakes. Ecological Monographs 1:231-331. benthic macroinvertebrates in Lake Sangchris occurred between 4 and 6 m, FiNDENEGC. I. 1955. Die profundale Fauna der Karntner Seen und ihr V'erhaltnis zu deren the transition zone from hardpan clay Trophiezustand. Pages 121-140 in Vittorio and sand to silt. Tonolli. ed.. Svmposium on biological. physical, and chemical characteristics of the 10. —The abundance and diversity of profundal zone of lakes. Istituto Italiano di benthic macroinvertebrates collected Idrobiologia, Memorie. supplemente 8. from substrate samplers in the discharge loviNO. A. J., and F. D. Miner. 1970. Seasonal channel indicated that increased water abundance and emergence of Chironomidae of temperature was not a limiting factor but Beaver Reservoir. Arkansas (Insecta: Diptcra). . Aug. 1981 Webb: Benthic Macroinvertebrates 377 Kansas Entomological Society Journal 4S: Richardson, R. E. 1921a The small bottom and 197-216. shore fauna of the middle and lower Illinois Johnson, W. H. 1964. Stratigraphy and petro- River and its connecting lakes, Chillicothe to graphy of Illinoian and Kansas drift in central Grafton: its valuation; its sources of food supply: Illinois. Illinois State Geological Survey Circular and its relation to the fishery. Illinois Natural 378. 38 p. History Survey Bulletin 13:363-522. JUDAY, C. 1921. Observations on the larvae of . 19216. Changes in the bottom and shore CoTethra punctipennis Say. Biological Bulletin fauna of the middle Illinois River and 40:271-286. its connecting lakes since 1913-1915 as a result Kramer, C. Y. 1956. Extension of multiple range of the increase, southward, of sewage pollution. tests to group means with unequal numbers of Illinois Natural History Survey Bulletin replications. Biometrics 12:307-310. 14:33-75. LiMNETics. Inc. 1972. A limnological survey of . 1 924. Changes in the small bottom fauna of Lake Sangchris, Illinois. Limnetics, Inc., Peoria Lake, 1920 to 1922. Illinois Natural Milwaukee. 274 p. History Survey Bulletin 15:327-388. 1973. A second limnological survey of . 1925. The Illinois River bottom fauna in Lake Sangchris, Illinois. Limnetics, Inc., 1923. Illinois Natural History Survey Bulletin Milwaukee. 42 p. 15:389-422. Main, R. A. 1963. A limnological study of C/iao6or- . 1928. The bottom fauna of the middle lis (Diptera) in Hall Lake, Washington. M.S. Illinois River, 1913-1925. IlHnois Natural thesis. University of Washington, Seattle. 106 p. History Survey Bulletin 17:387-475. Margalef, R. 1958. Temporal succession and Roback, S. S. 1969. Notes on the food of Tanypod- spatial heterogeneity in phytoplankton. Pages inae larvae. Entomological News 80:13-19. 323-349 m A. A. BuzzatiTraverso. ed. Perspec- Scott, W., R. O. Hile, and H. T. Spieth. 1928. tives in marine biology. University of California Investigations of Indiana Lakes. I. A Press, Berkeley. quantitative study of the bottom fauna. Lake Massengill, R. R. 1976. Benthic fauna: 1965-1967 Wawasee (Turkey Lake). Indiana Department versus 1968-1972. Pages 39-53 m D. Merriman and of Conservation Publication 77. 26 p. River of in L. M. Thorp, eds. The Connecticut Stahl, J. B. 1966. The ecology Chaoborus ecological study. American Fisheries Society Myers Lake, Indiana. Limnology and Monograph 1 Oceanography 11:177-183. O'Connell, T. R.. Jr., and R. S. Campbell. 1953. Thienemann, a. 1922. Die beiden Chironomus- The benthos of Black River and Clearwater arten der Tiefenfauna der norddeutschen Seen. Lake, Missouri. The Black River Studies. Archiv fur Hydrobiologie 13:609-646. University of Missouri Studies 26(2):25-41. Welch, P. S. 1952. Limnology. McGraw Hill Paloumpis. a. a., and W. C. Starrett. 1960. An Book Company, Inc., New York, 538 p. ecological study of benthic organisms in three Wohlschlac, D. E. 1950. Vegetation and in- Illinois River flood plain lakes. American vertebrate life in a marl lake. Investigations of Midland Naturalist 64:406-435. Indiana Lakes and Streams 3:321-372. Reproduction, Growth, Distribution, and Abundance of Corbicula in an Illinois Cooling Lake Herbert Dreier and John A. Tranquilli ABSTRACT cooling loop (25-67 clams/m2) except the discharge canal than it was in the control season, rate, The spawning growth arm (8 clams/m^), suggesting that the population density of Corbicula were and fwpularion in the cooUng loop benefited from examined in the intake, discharge, and power plant operations. control arms of Lake Sangchris, a cooling A clam die-off apparently occurred in lake for a 1,232-MW coal-fired electrical the vicinity of the discharge canal as a generating station. Clams in areas result of highly elevated water adjacent to the power plant were temperatures (up to 40°C) during the observed to obtain data that might aid in summer of 1975, but by February 1976 controlling this organism, which had the the canal had been repopulated. A low potential of becoming a serious fouling survival rate for young-of-the-year agent at the station. Major spawning individuals (<.5 mm in length) was seasons were observed in all three arms of indicated in Lake Sangchris, because the lake during the spring and the fall. larger clams comprised only 12 percent of The average annual growth of clams the total clam population. Predation by caged in the discharge arm was fishes in the lake was presumed to be a significantly greater (P<0.05) than the major cause of mortality for smaller growth of clams in the intake and control clams. arms, and was attributed to the extended growth period made possible by the INTRODUCTION heated water. The annual growth of The introduced Asiatic clam, marked individuals was inversely Corbicula fluminea (= C. manilensis) proportional to original length, small has extended its range across the United clams growing faster than large clams. States since its discovery in 1938 in the Estimates of annual growth based on the Columbia River near Knappatan, growth of caged clams indicated that Washington. Major concerns regarding lengths of 21, 31, 36, and 40 mm were the introduction of Corbicula into various reached by clams caged in the discharge streams and reservoirs across the country arm after 1, 2, 3, and 4 years of life, are that it may serve as a fouling respectively. organism in electrical generating stations The Corbicula population density and other industrial plants that use large varied inversely with depth; higher amounts of untreated water and that its concentrations were found in substrates prolific nature may allow it to out- composed of 2-10 cm of loose sand. silt, compete and thereby reduce our native or clay over hard clay than were found in moUuscan fauna (Sickel 1973; Gardner et areas where a thick layer of loose silt was al. 1976). present. In littoral areas, the mean clam In 1973, Corbicula was first noticed in reservoir in density was higher in all sections of the Lake Sangchris, a cooling central Illinois. A short time later it was Herbert Dreier is with the Macon County Heahh found inside the Kincaid Generating Department, Decatur. Illinois, and Dr. John A. Station, but it had not yet created Tranquilli is an Associate Aquatic Biologist, Section of Aquatic Biology, Illinois Natural History Survey. mechanical fouling problems as serious as This chapter submitted in Dec. 1977. those reported in plants of the TVA 378 . Aug. 1981 Dreier & Tranquilli: Corbicula 379 •^" r •r-'«r.^- ""-^ "^ Corbicula fluminea from -^ ••? Lake Sangchris. W*^?. system (Goss & Cain 1975). The overall control (Fig. 1), each approximately 8 km objective of this study, begun in April in length. The water, used for cooling a 1975, was to investigate various aspects of 1,232-MW coal-fired electrical generating the life history of a natural population of plant, is drawn from the intake arm, Corbicula and to provide biological heated a maximum of 9°C, and emptied information that might aid in its control into the discharge arm, creating a 16-km if it should become a serious problem at "cooling loop." The third arm is not in- Kincaid Generating Station. Although cluded in the cooling loop and was used numerous studies of this clam have been as a control area. The slag pond adjacent' conducted since it was discovered in this to the power plant is a diked 32-ha area, country, most have occurred in areas of where unheated water is used to slurry the the United States with more moderate residue of burned coal (slag). Excess temperatures than those in central water from the slag pond, which serves as Illinois. a settling basin, is returned to the lake by Specific objectives of this study were a large pipe that empties into the (1) to compare the spawning season, discharge canal. Larimore & Tranquilli growth rate, and population density of (1981) present a more detailed descrip- Corbicula in the discharge, intake, and tion of the entire study area in the in- control arms of Lake Sangchris and (2) to troductory chapter of this monograph. observe the clam populations in the 1 immediate vicinity of the power plant at the intake and discharge canals, the slag SPAWNING pond, and the intake structure (cribhouse). The spawning seasons of Corbicula in the three arms of Lake Sangchris were MATERIALS AND METHODS determined by counting the number of larvae (trochophores or veligers) and eggs DESCRIPTION OF THE STUDY in the marsupial gills of adult clams. The ' AREA actual rate at which larvae or eggs were Lake Sangchris in central Illinois has released by adult clams was not an area of 876 ha and is composed of determined. However, studies by I three Villadolid Del Rosario (1930). , arms, intake, discharge, and & 380 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 DISCHARGE & CONTROL ARM JUNCTION CONTROL ARM Fig. 1 .—Map showing three main areas of Lake Sangch'ris; intake arm (squares), discharge arm (circles), and control arm (triangles) Eight sampling areas (seven lake areas and the slag pond), where the distribution and abundance of Corbicula were determined during the summer of 1975. are also labeled Heinsohn (1958), and Aldridge & America is C. Jlummea (Muller 1774) and McMahon (1976) indicated that because Smith et al. (1979) found little Corbicula release a small percentage of genetic variability among Corbicula their larvae or eggs daily over a few populations from California, Texas, weeks rather than releasing most of them Arkansas, Tennessee, and South at once. Carolina. The name Corbicula fluminea (= C. Corbicula ranging in length from 16 manilensis ) was used because Britton & to 41 mm were examined for egg^ and Morton (1979) concluded that the single larvae. Villadolid & Del Rosario (1930). introduced species of Corbicula in North Heinsohn (1958), and Sinclair & Isom Aug. 1981 Dreier & Tranquilli: Corbicula 381 (1963) determined that clams of those 2.54-cm^ wire mesh to provide free water sizes were sexually mature. From 8 May circulation. A natural substrate was to 22 October 1975 five clams were always provided by placing a few collected approximately biweekly from a centimeters of lake bottom material specific area in each of the three arms of within each cage. Clams produced during Lake Sangchris. Additional clams were 1975 were collected from the growth collected from the discharge arm on 23 cages during May 1976 and counted. April and from all three arms on 14 Growth of young-of-the-year clams was November and 31 December 1975. All determined by measuring their anterior Corbicula were taken from shoreline to posterior length to the nearest areas in water less than 1.5 m deep and millimeter with a dial caliper. To were preserved in formalin until they determine the effect of water could be examined. temperatures on Corbicula growth, To determine the number of eggs and temperatures in each arm of the lake were recorded at approximately biweekly larvae, the gills were removed and divided into small pieces under a intervals. dissecting microscope. When it appeared Annual growth of adult Corbicula in that 300 or fewer eggs and larvae were all parts of Lake Sangchris was present, they were counted as the gills determined by studying individuals were disassembled. When more eggs and longer than 10 mm that were marked larvae were present, the gills were divided during the spring of 1975. Each into small sections and the eggs and individual was identified by scratching a larvae were washed into a container with series of marks on either or both valves a known volume of water. Five subsamples with a saw blade, and each was placed in were taken, and the eggs and larvae in a growth cage in the original sampling each subsample were counted. The total area. Three cages were placed in the numbers of eggs and larvae in each clam discharge arm, three in the control arm, were estimated with the equation: and four in the intake arm; each cage received 25-40 clams. One year later the SSN X SV N = clams were recovered from the cages, and ssv the growth of individuals was determined to the nearest 0.1 mm. Clams produced where N = the estimated number of in these cages during 1975 were also larvae in each adijlt, SSN = the number counted and measured to increase the of larvae in the subsample, SV = the sample size for determination of the sample volume, and SSV = the annual growth of larvae. subsample volume. The final estimate The growth of adult Corbicula during was an average of the five subsample the summer was determined by returning totals. the clams marked during 1975 to their Veliger and trochophore larval stages respective cages in the three arms of the and eggs were differentiated according to lake in May 1976 and measuring them descriptions by Sinclair Isom (1963). & again in September 1976. The summer growth of 1975 year class Corbicula was GROWTH studied by returning to the growth cages young-of-the-year clams with a known The growth of Corbicula in Lake length frequency distribution along with Sangchris was determined by several their marked parents. methods. The first method involved determining the annual growth of larvae The growth of Corbicula in the produced in cages during 1975. One cage discharge arm was observed monthly containing 15 adult clams was placed in from 17 May until 16 November 1976. ' each arm of the lake during May 1975. Clams longer than 7 mm were measured Growth cages (1.0 x 0.5 x 0.25 m) con- to the nearest millimeter and put into one sisted of a wooden frame covered by of four cages. To determine the growth of i 382 Illinois Natural History Survey Bulletin Vol. 32, An. 4 clams in each 1-mm size group, they were one study area more than those obtained separated by 4-mm intervals. The size in another. The populations of two size distribution placed in cage 1 was 7, 11, groups of Corbicula, those longer than 5 15, 19 mm, etc. Similar size distributions mm and those 5 mm or shorter, were were created in cages 2,3, and 4 with the determined for each area. Clams shorter smallest individuals measuring 8, 9, and than 5 mm were considered to have been 10 mm, respectively. These cages (50 x 50 produced during 1975. X 10 cm) were constructed of 0.6-cm* wire In areas which are more strongly mesh and were placed in the discharge influenced by power plant operations arm near the mouth of the discharge (discharge and intake canals) the canal at the site where the clams had population was sampled again during been collected. The clams in each cage February 1976 for comparison with data were measured monthly to determine from the previous summer. their average growth. Additional small To determine the population density clams were collected from the same area and size distribution of clams inside the of the lake several times during the generating station, Ponar dredge hauls summer to replace those that had grown were taken near each of six rotating to larger sizes. screens inside the water intake structure Corbicula growth rates observed in (cribhouse) during May 1976. The intake various parts of the lake were compared structure was sampled again during by a one-way analysis of variance using September 1976 to monitor changes in the statistical analysis system (SAS) the clam population. regression procedure on an IBM 360/75 computer. Growth rates of clams of different sizes were adjusted for by using RESULTS AND DISCUSSION the reciprocal length (one h- initial length) as a covariable before comparing SPAWNING the growth of clams in different areas of Marsupial gills of Corbicula did the lake. Other statistical tests used were not contain larvae and eggs at the same standard procedures outlined in Steel & time. Several clams did simultaneously Torrie (1960). contain trochophore and veliger lar^'ae, but one stage always greatly outnumbered the other. The average size of all clams POPULATION DENSITY examined for eggs and larvae from the The Corbicula populations in seven discharge, intake, and control arms was areas of Lake Sanchris and in the slag 25.0, 29.4, and 27.7 mm, respectively. pond (Fig. I) were studied from 11 June Small numbers of larvae and or eggs to 12 August 1975. The study areas in the were found in Corbicula collected from lake were the discharge canal, discharge the discharge arm on 23 April 1975 at a arm, control arm, control and discharge water temperature of 21.5°C and in the arm junction, intake arm-north, intake intake and control arms on 8 May 1975 arm-south, and intake canal. Three (Table 1), when water temperatures were 22.9-cm' Ponar dredge hauls were taken 21° and 22''C, respectively. There was a at each meter depth, working along simultaneous increase in the average transects from the shoreline to the middle number of larvae in clams from all three of the lake. A sieve with a mesh size of 2 arms between 8 and 21 May as mean mm was used to separate clams from the water temperatures (N = 3) increased substrate. The number, size, location, (Fig. 2) to 24.3°, 22.6°, and 23.'8°C in the and depth of clams and the bottom type discharge, intake, and control arms, at each sampling site were noted. respectively. In California, Heinsohn Approximately the same number of (1958) correlated larval development samples was taken from the eight study from March through June with optimal areas every week so that reproduction water temperatures of around 20°C. Isom would not influence results obtained in (1971) reported that spawning occurred Aug. 1981 Dreier & Tranq^uilli: Corbicula 383 Table 1. —Average numbers of larvae (veHger or trochophore) and eggs in marsupial gills of Corbicula from the three arms of Lake Sangchris during 1975- Five clanns from each area were examined on each date. 384 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 the mean weekly water temperature cages in the discharge, intake, and (N = 3) was 20.8°C. This second spawning control arms during 1975 was 20.9, 18.1, season extended from early October and 16.4 mm, respectively (Fig. 3). through mid-November in the discharge According to results of Duncan's new and intake arms, and occurred during multiple-range test (Steel & Torrie 1960), mid- October in the control arm. In growth of young-of-the-year clams from California Heinsohn (1958) found a the discharge arm was significantly major Corbicula reproduction peak greater (P< 0.05) than it was in the occurring from late April through June, a control arm, but not significantly greater near absence of reproduction during than growth in the intake arm. In the midsummer, and a second minor same analyses, the mean growth of clams reproductive peak in late August and in the intake and control arms was not early September. In the Delta-Mendota different. In similar studies conducted at Canal, California, Eng (1979) also found the Kingston Steam Plant, Tennessee, two peaks in spawning activity, resulting Mattice (1979) found that the growth of in the appearance of two size classes Corbicula caged in the discharge was annually. Aldridge & McMahon (1976) significantly greater than that of found that a natural population of Corbicula caged in the intake for Corbicula manilensis in a Texas cooling comparable periods. lake produced two generations per year, In our study the greater annual one in the spring and one in the fall. growth of young-of-the-year clams in the The reproductive potential of discharge arm was attributed to the Corbicula in Lake «Sangchris was shown extended growth period made possible by by maximum larval counts of 21,030, the heated water from the generating 16,996, and 16,505 in individual clams station. In the discharge arm, higher from the discharge, intake, and control water temperatures contributed to an arms, respectively. earlier completion of spawning in the spring and allowed growth to continue GROWTH later into the fall than was possible in the In general, the greatest growth intake or control arms. O'Kane (1976) occurred in cages in the discharge arm determined that young-of-the-year and the least growth in cages in the Corbicula from unheated Texas control arm. Average annual growth of reservoirs grew in 1 year to a mean length 1975 year class Corbicula produced in of 14-15 mm and to a maximum length = DISCHARGE ARM, i(= 20.9, N = 1,925 = INTAKE ARM, I = 18.1, N = 1,990 • • = CONTROL ARM, I = 16.4, N = 2,225 Fig. 3. —Average annual size of young-of-the-year Cor- bicula in cages in the discharge, intake and control arms of Lake Sangchris dur- ing 1975. 1 1 1 1 1 1 T^ 1 ^ I 8 10 12 W 16 18 20 22 24 26 28 LENGTH OF CLAMS (mm) J Aug. 1981 DrEIER & TRANqUILLi: CORBICULA 385 of 25 mm. Aldridge & McMahon (1976) incipient lethal temperature of 34°C. found that Corbicula had a somewhat Additional sampling in the discharge faster growth rate in a Texas cooling canal indicated a summer die-off, lake, where a more southerly latitude because by late summer only a few live allowed an even longer growing season. clams, along with numerous empty shells, In the Texas cooling lake, larvae could be found in a region where there produced during a mid- April to late July had been a large concentration of live spawning period gfrew to a mean length of clams during the previous spring. Clams 28.7 mm by mid-December of that year, in two other cages in the discharge arm and larvae produced during a late August during the summer of 1975 survived to late November spawning period grew throughout the year. They may have to a mean length of 31.0 mm by mid- been partially buffered from the high August of the following year. water temperatures, however, because Extremely high water temperatures one cage was in a cove and the other was (up to 40°C) occurred in areas of the approximately 1.25 km downstream from discharge arm during the summer of the entrance of the discharge canal into 1975, and all clams in one cage near the the lake. discharge canal died. The death of those The annual growth of individually clams was believed to be directly related marked adult clams was inversely to the high water temperatures, because proportional to their original length, with Mattice & Dye (1976) determined that smaller clams growing faster than larger Corbicula acclimated at 30°C individuals. Smaller clams (10-13 mm) experienced 100-percent mortality when grew as much as 18.7 mm per year, while exposed to 43°C for 30 minutes and larger clams (34-39 mm) grew only 50-percent mortality at the upper 1.8-4.8 mm per year (Fig. 4). O'Kane • = DISCHARGE ARM o = INTAKE ARM A = CONTROL ARM 20 18 16 14 & 12 '-U'l. CD 10 8 6 ^ I 2 ^ I I I I 2 I 5 I lb I 14 I 18^^ 22 26 30 34 38 4 8 12 16 20 24 28 32 36 ORIGINAL LENGTH OF CLAM (mm) in the three arms of Fig. 4.—Annual growth of individually marked Corbicula of different sizes [Lake Sangchris from May 1975 to May 1976. 386 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 (1976) and Britton et al. (1979) also Table 2. — Mean summer growth in found that smaller Corbicula increased in millimeters of young-of-the-year Corbicula pro- duced in the discharge and intake arms of Lake length at a faster rate than did larger Sangchris during 1976, Growth was determined ones. The initial lengths of clams caged by length frequency distribution analysis in each arm were adjusted to a common (percentage frequency). the least-squares method so that mean by Length their average growth could be determined. After having been adjusted for initial length, the growth of marked clams in the discharge arm was found to be much greater {P< 0.01) than the growth of those in the intake and control arms, while the growth of clams in the latter two arms was not different. Clams from the discharge arm grew an average of 10.2 mm. while those from each of the other two arms grew only 7.8 mm per year. A 1976 year class of clams was found inside cages raised in late September 1976 to determine summer growth of both individually marked adults and 1975 year class clams. The 1976 young-of-the-year clams produced in one cage in the discharge arm had grown to a mean length of 13.3 mm, while those produced in two cages in the intake arm had grown to mean lengths of 12.9 and 13.6 mm during the summer (Table 2). O'Kane (1976) reported that young-of-the-year Corbicula in unheated Texas reservoirs grew an average of 11-12 mm and a maximum of 20 mm in 4 months. Clams of the 1975 year class, having a bimodal length frequency distribution (representing spring and fall Aug. 1981 Dreier & Tranquilli: Corbicula 387 Table 3. —Average growth in millimeters of individually marked Corbicula caged in the discharge, intake, and control arms of Lake Sangchris from May to September 1 976. The number of clams pres- ent in each 1-mm length group is shown in parentheses. May 1976 Clam 388 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 4. —Average monthly (17 May-16 November 1976) growth of Corbicula caged in the discharge arm of Lake Sangchris, The number of clams present in each 1-mm length group at the start of each period is shown in parentheses. Length in Aug. 1981 Dreier & Tranquilli: Corbici'la 389 rubble slopes and that density increased complex habitats, which also increased directly with depth of water. He directly with increasing depth. In the associated higher densities with more Altamaha River of Georgia. Gardner et ^^ £ I 390 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 al. (1976) found Corbicula were more intake arm south. The average density in abundant on substrates of sand in the control arm littoral zone was at least combination with mud or detritus than three times lower at 8 clams/ m^, which they were on substrates which were suggested that the population in the cool- predominantly mud or detritus. In Dale ing loop benefited from power plant Hollow Reservoir, Tennessee, Abbott operations that supplied heat and/or cur- (1979) found highly significant rent. The lowest clam density in the lit- differences between 8-m and 12-m depths toral zone was in the discharge canal (4 for shell sizes and densities, with larger clams/m^). That low population was individuals occurring at 8 m and greater attributed to the clam die-off during the densities occurring at 12 m. Temperature summer of 1975 as a result of 40''C water differences between the 8- and 12-m temperatures. In contrast, Webb (1981) depths were hypothesized as the major reported that populations of soft-bodied factor affecting shell size, whereas benthic organisms (mostly Chironom- substrate type appeared to modify idae) were not affected by high water density. The highest densities of temperatures in the discharge canal, but Corbicula in several Texas reservoirs were instead were adversely affected by the associated with sand-gravel substrates presence of a shifting slag substrate. and boulder rubble, while the lowest densities were noted in fine sand, in sharp Young-of- the-year individuals granite gravel, and in substrates constituted 88 percent of all clams in containing a high percentage of clay and Lake Sangchris during the 1975 sih (O'Kane 1976). Eng (1979) reported population study (Table 6). The slag densities in sediment bars of the concrete- pond, adjacent to the lake, contained the lined Delta- Mendota Canal, California, highest population of large clams (12-15 of 10,000-20,000 clams/m2. mm in length) and was the only sampling During the summer of 1975, the mean area where clams > 5 mm in length were density of clams in the littoral zone (1-3 more numerous than smaller individuals m depth) was higher in all areas of the (Fig. 6). The low number of adults in cooling loop (except the discharge canal) Lake Sangchris in relation to the number than it was in the control arm (Fig. 6). of juveniles indicated a low survival rate The highest average clam population in for young-of-the-year clams. In contrast, the littoral zone was found within the a high survival rate of young-of-the-year intake canal (64.7/m*). In other areas of clams was common in growth cages, the cooling loop average concentrations where the larvae were protected from decreased gradually from 50 clams/m^ in predation. For example, 0.5x0. 5x0. 5m the discharge arm to 25 clams/m^ in the cages, each containing 15 adult clams. AMBIENT Fig. 6. —Average densities of Corbicula >5 mm long (solid) bars) and <5 mm long (open bars) in the littoral zone of seven sampling areas of Lake Sangcfiris and tfie slag pond during tfie summer of 1975. U3 o o q: ac z «t t- 13 oi: oz o O aO ct Aug. 1981 Dreier & Tranquilli: Corbicula 391 were placed in the discharge, intake, and concentration further suggested that the control arms during the spring of 1975, discharge canal area was repopulated and 1 year later they contained 5,720, during the fall by larvae produced in the 13,060, and 4,544 clams/m^, respectively. intake canal, the power plant, and the In the lake, fish predation was believed to slag pond. Some of the small clams were be a major source of mortality for small attached by byssal threads to particles of clams. Fish food-habit analyses revealed that slag in the substrate. Apparently, large Corbicula were regularly consumed by concentrations of small clams settle in the bluegill {Lepomis machrochirus), discharge canal every year and are later freshwater drum (Aplodinotus reduced by fish predation and/or high grunniens) , and channel catfish summer water temperatures. (Ictalurus punctatus) in Lake Sangchris When the intake canal was (Sule et al. 1981). Rinne (1974) similarily reexamined during February 1976, a suggested that fish predation was a factor much smaller clam population was in affecting the density of Corbicula in present than was there during the two Arizona reservoirs. The greater previous summer. In 36 samples taken abundance of large clams in the slag during February, there was an average of pond was attributed to a reduced rate of only 3.1 clams/m^, whereas there was an fish predation there. Tranquilli et al. average of 81.3 clams/m'' in 44 samples (1977) surveyed the slag pond fish during the previous summer. Very few population and found only black empty shells were found during February; bullheads (Ictalurus melas) during 1974 however, a 0.3-m/second current created and only black bullheads, gizzard shad by the circulating water pumps may have (Dorosoma cepedianum), and one yellow drawn live and/or dead cljims past the trash bass (Morone mississippiensis) during racks at the entrance of the cribhouse. 1975. Since gizzard shad and yellow bass Examination of water quality parameters feed on plankton, black bullheads were recorded in the intake canal between the the only potential clam predators summer of 1975 and February 1976 by present. However, the slag pond does Brigham (1981) suggested no cause for serve as a waterfowl refuge during the the observed reduction in clam autumn, and predation of larger clams population density. by waterfowl may have been fairly high. reported Sanderson & Anderson (1981) The intake structure of the power that the slag pond attracts approximately plant was sampled in May 1976 (N=6), one-half water- of the more than 100,000 and an average concentration of 6,788 fowl that congregate at Lake Sangchris j clams/m^ was found on the cribhouse every year and that percent of the 36 floor. Approximately 70 percent of these waterfowl shot hunters at the lake con- by clams ranged in length from 14 to 19 tained Corbicula shells in their gizzards. mm, indicating that most were produced Quantitative samples in the taken during 1975. The umbones and ventral discharge canal area of Lake Sangchris margins of clams from the cribhouse were during February 1976 demonstrated that scratched and worn, apparently the result Corbicula were much more abundant of their having been moved about by than they had been during the previous water currents. The population inside the summer. Average concentrations of 441 cribhouse may have been established by and 418 clams/m^ were found at depths larvae or juveniles passing through the of 2 and 3 m, respectively, whereas only 8 6.2-mm^ wire mesh barrier or by adults and 6 clams/m' were found at these being carried over the vertically rotating depths during the of 1975. In summer screen to the cribhouse floor. Spawning February, 48 percent of the clams were j in the cribhouse probably occurs during 1 less than 3 mm in length, and all were less most of the warmer months, as it does in than 8 in length, mm indicating that they the intake arm. From the cribhouse, had been produced during the fall of larval clams can be introduced directly 1975. That relatively high February clam into the generating station, where they Vol. 32, Art. 4 392 Illinois Natural History Survey Bulletin water temperatures (up may attach themselves to pipes by byssal caused by elevated threads. to 40»C). 6. — Monthly examination of growth floor was sampled The cribhouse in the discharge arm during 1976 showed 1976, and an again during September the fastest growth by clams of all sizes only 1,158 clams/m'' was average of during the first month of study (May- dredge hauls. The found in two June, decreasing progressively until 83-percent reduction in numbers through October-November. have occurred the summer may 7. — Estimates of annual growth, of naturally, may have been an effect based on the growth of caged clams small sample size, or may have been during 1975 and 1976, indicated that shutdown of all the related to a complete clams in the discharge arm reached for days of circulating water pumps 6 lengths of 21, 31, 36, and 40 mm after 7 -week period in each week during a their 1st, 2nd, 3rd, and 4th years of life, case, rapid midsummer. In any respectively, and were always larger than density should fluctuation in population clams of the same age from the intake with organisms be expected when dealing and control arms. which have high such as Corbicula, 8. — In Lake Sangchris the Corbicula fecundities, produce two generations population density varied inversely with highly vulnerable to per year, and are depth; higher concentrations usually were predation by fishes. found in areas associated with a substrate of 2-10 cm of loose sand, silt, or clay over hard clay than in areas with a thick layer SUMMARY of loose silt. 9. — During the summer of 1975 the was 1.— During 1975, Corbicula in Lake mean clam density in the littoral zone in of the cooling loop Sangchris had major spawning seasons higher in all sections the discharge canal where a die- the spring and in the fall. (except occurred) than it was in the control 2.— The average annual ;growth of off arm, suggesting that the population in young-of-the-year clams in the discharge the cooling loop benefited from power arm during 1975 (20.9 mm) was plant operations that supplied heat significantly greater (P< 0.05) than the and/or current. average growth of clams in the intake 10. -During the 1975 Lake Sangchris (18.1 mm) or control arms (16.4 mm). Corbicula population study, few adults 3. — Annual growth of marked were found in relation to the number of individuals was inversely proportional to juveniles, indicating low survival by original length, with smaller clams their young-of-the-year clams. Fish predation growing faster than large clams. The was believed to be a major source of growth of marked clams in the discharge mortality for small clams. A lower rate of arm was much greater (P< 0.01)than was fish predation upon young-of-the-year the growth of individuals in the intake or clams in the slag pond probably control arms. accounted for the higher proportion of annual growth of 4. — The greater adults found there. was clams inthe discharge arm during 1975 11.— Quantitative samples collected period attributed to the extended growth from the discharge canal in February water from made possible by the heated 1976 revealed that after the clam die-off the generating station. during the summer of 1975 the canal was during the fall by larvae 5. — A partial clam die-off in the repopulated intake canal, the discharge arm near the discharge canal produced in the and the slag pond. during the summer of 1975 probably was cribhouse, Aug. 1981 Dreier & Tranquilli: Corbicula 393 Symposium Proceedings. Texas Christian REFERENCES CITED University, Fort Worth, Asiatic clam (Corbicula Abbott, T. M. 1979. , and L. L. Dye. 1976. Thermal tolerance of fluminea) vertical distributions in Dale Hollow the adult Asiatic clam. Pages 130-135 in G. W. Reservoir. Tennessee. Pages 111-118 in J. C. Esch and R. W. McFarlane, eds., Thermal Britton. ed.. First International Corbicula ecology II. Energy Research and Development Symposium Proceedings. Texas Christian Administration Symposium Series University. Fort Worth. (CONF-750425), Augusta, GA. Aldridge. D. W., and R. F. McMahon. 1976. O'Kane, K. D. 1976. A population study of the Population growth and reproduction in the life- exotic bivalve Corbicula manilensis (Phillipi, cycle of Corbicula manilensis Philippi. Abstract 1841) in selected Texas reservoirs. M. S. Thesis. of paper presented at the 39th annual meeting, Texas Christian University. American Society of Limology and introduced Asiatic clam, RiNNE, J. N. 1974. The permission of Oceanography. (Cited with Corbicula, incentral Arizona reservoirs. Nautilus authors.) 88(2):56-61. quality in a cooling Brigham. A. R. 1981. Water Sanderson, G., and W. L. Anderson. 1981. Water- 290-319 in R.W. Larimore water reservoir. Pages fowl studies at Lake Sangchris. Pages 656-690 in and A. Tranquilli, eds.. The Lake Sangchris Tranquilli, eds.. J. R. W. Larimore and J. A. The cooling lake. study: case history of an Illinois Lake Sangchris study: case history of an Illinois Bulletin 32(4). Illinois Natural History Survey cooling lake. Illinois Natural History Survey R. Coldiron, L. P. Evans, Jr. Britton, J. C, D. Bulletin 32(4). R. C. GoLiGHTLY, K. D. OKane, and J. 1973. new record of Corbicula SicKEL, J. B. A the growth TenEyck. 1979. Reevaluation of manilensis (Philippi) in the southern Atlantic (Muller). Pages pattern in Corbicula fluminea slope region of Georgia. Nautilus 87(1): 11-12. International 177-192 in J.C. Britton. ed., First Sinclair, R. M., and B. G. Isom. 1963. Further Texas Corbicula Symposium Proceedings. studies on the introduced Asiatic clam Christian University, Fort Worth. (Corbicula) in Tennessee. Tennessee Stream and B. Morton. 1979. Corbicula in North Pollution Control Board and Tennessee evaluated. America: the evidence reviewed and Department of Public Health, Nashville. 78 p. Pages. 249-287 in C. Britton, ed. First P. Burke, R. K. J. Smith, M. H., J. Britton, International Corbicula Symposium Proceedings. Chesser, M. W. Smith, and Hagen. 1979. Texas Christian University, Fort Worth. Genetic variability in Corbicula, an invading of the Asiatic Eng, L. L. 1979. Population dynamics species. Pages 243-248. in]. C. Bntton, ed.. First clam, Corbicula fluminea (Muller), in the International Corbicula symposium concrete-lined Delta-Mendota canal of central Proceedings. Texas Christian University, Fort California. Pages 39-68 in]. C. Britpn, ed.. First Worth. International Corbicula Symposium Proceedings. McNurney, and D. R. Halffield, Sule, M. J., J. M. University, Fort Worth. fishes Texas Christian Jr. 1981. Food habits of some common R. Woodall, Jr., A. A. areas of Lake Gardner, J. A., Jr., W. from heated and unhealed invasion Staats, Jr., andj. F. Napoli. 1976. The Sangchris. Pages 500-519 m R. W. Larimore and Philippi of the Asiatic clam Corbicula manilensis A. Tranquilli, eds., The Lake Sangchris study: J. Nautilus in the Altamaha River, Georgia. case history of an Illinois cooling lake. Illinois 90(3):117-125. Natural History Survey Bulletin 32(4). plant Goss, L. B., and C. Cain, Jr. 1975. Power Steel, R. G. D., andJ. H. Torrie. 1960. Principles fouling by condenser and service water system and procedures of statistics. McGraw-Hill Book presented at Corbicula, the Asiatic clam. Paper Company, Inc. New York. 481 p. the biofouling workshop, Johns Hopkins McNurney, M. Sule, R. Tranquilli, J. A, J. M. University, Baltimore, MD. KocHER, and R. W. Larimore. 1977. fish Heinsohn, G. E. 1958. Life history and ecology of population and natural history studies. Pages A. the freshwater clam, Corbicula fluminea. M. 4.1-4,107 in Annual report for fiscal year 1976, Thesis. University of California, Berkeley. 64 p. Lake Sangchris project. Illinois Natural History of IsoM, B. G. 1971. Evaluation and control Survey, Urbana. macroinvertebrate nuisance organisms in fresh- Villadolid, D. v., and F. G. Del Rosaria. 1930. water industrial supply systems. Paper presented Some studies on the biology of Tulla (Corbicula at the 19th annual meeting. Midwest manillensis Philippi), a common food clam of Dame, Benthological Society. University of Notre Laguna de Bay and its tributaries. Philippine IN. Agriculturist 19:355 382. Larimore, R. W., andJ. A. Tranquilli. 1981. The Webb, D. W. 1981.The benthic macroinvcrtebrates Lake Sangchris project. Pages 279-289 m R. W. from the cooling lake of a coal-fired electric Tranquilli, eds.. The Lake in R. W. Larimore and J. A. generating station. Pages 358-377 study: case history of an Illinois cooling Tranquilli, eds., the Lake Sangchris Larimore and J. A. lake. Illinois Natural History Survey Bulletin Sangchris study: case Hi.story of an Illinois 32(4). cooling lake. Illinois Natural History Survey S. 1979. Interactions of Corbicula sp. Mattice, J. Bulletin 32(4). with power plants. Pages 119-138 m J. C. Britton, ed.. First International Corbicula Aquatic Macrophytes in Lalce Sangchris Robert L. Moran ABSTRACT stand biomass was greatest in the discharge arm of the lake. The aquatic vascular plants in an P. nodosus had lakewide 876-ha cooling-water reservoir were a distribution, but achieved its greatest stand biomass in the intake studied from 1973 to 1976 to document arm. Inorganic tissue analyses the vegetational development of this of P. nodosus showed that the highest reservoir and to determine what effects, if concentrations of aluminum, any, the thermal effluent may have had boron, copper, magnesium, upon the vegetation. The vegetation was manganese, phosphorus, and zinc were in plants mapped for 4 consecutive years, the from the discharge arm. biomass of several stands of Nelumbo lutea and Potamogeton nodosus was INTRODUCTION determined, and an inorganic tissue analysis of P. nodosus was performed. Lake Sangchris is an 876-ha Shoreline erosion and turbidity had reservoir formed in 1963-1966 by the greatest influerKe upon the occurrence damming Clear Creek to supply cooling and development of vegetation. The species water for Commonwealth Edison's immigration-extinction rate at Lake 1 ,232-megawatt coal-fired Kincaid Sangchris was about 1.9^2.3 species per Generating Station. The lake is composed of three arms with a general year. It is estimated that the maximum orientation. number of species will be about 28, and this north-south The electric number should be reached in 1985 when generating station lies between the western middle arms and is the lake is 21 years old. Some estimates and from the literature suggest 50 as the connected to them by canals. The middle maximum number of species in arm receives the thermal effluent and has reservoirs, and this number could be been designated the discharge, or reached by the year 2014. warmwater, arm; the western arm Elevated water temperatures within supplies the cooling water intake and is the intake, or cool-water, the discharge arm were found to referred to as accelerate the development of N. lutea arm. Together these two arms form the and P. nodosus. The distribution of N. cooling loop. The third, eastern, arm is lutea was confined to an area within the not directly involved in the cooling loop cooling loop with an annual thermal flow and has been named the control arm regime about 0.75°C warmer than the (Fig. 1). ambient water temperature, but not The purpose of this study was to exceeding 37.6°C for more than 2.5 document the development of vegetation in reservoir to determine what percent (9 days) of the year. The spring the and onset of N. lutea growth was earliest and effects the operation of the Kincaid Generating Station and its thermal discharge had upon two aquatic vascular Robert L. Moran is Director. Division of Air Pollution Control, Vigo County Health plants, Nelumbo lutea (Willd.) Pers. Department. Terre Haute. Indiana. (American lotus) and Potamogeton This chapter submitted in July 1978. nodosum Poiret (American pondweed). 394 I Aug. 1981 Moran: Aquatic Macrophytes 395 V- SOUTH '\ v..~ L \ / / lSLAG fPOND,6 ^ ^% POWER • rSTATION TOWEY c>e i i } K \ 3 kilometers .^ ^ r i ii LAKE SANGCHRIS stations. Fig. 1 — Lake Sangchris and its sampling luipxLJQQC determined from Fehrenbacher et al. (1950). SOILS VEGETATION surveys were The soils comprising the basin and The vegetational immediate shoreline area were accomplished by visual inspection of the 396 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 shoreline and shallows from a boat Analyses for aluminum, boron, calcium, during July and/or August each year. copper, iron, magnesium, manganese, The occurrence and approximate phosphorus, potassium, silicon, sodium, distribution of each species were recorded and zinc were performed by Dr. T. Peck, on a map with a scale of 1:4,000. These Professor of Soil Chemistry, University of surveys were conducted by Dreier (1974), Illinois, in a Jarrell-Ash Mark-IV Ebert Frakes & Moran (1975), and Moran direct-reading stigmatic spectrograph 3.4 (1977a). m with a dispersal rate of 5 angstroms/mm. BIOMASS DISCUSSION Potamogeton nodosus samples, RESULTS AND including roots, were harvested in three 0.255-m2 plots from each of four plant SOILS forming Lake beds on 5 August 1974 and from eight The stream beds silt loam plant beds on 24 July 1975. Nelumbo Sangchris have Radford lutea samples, including rhizomes, were bottoms. On either side is a Hickory harvested in the same manner from six gravelly loam, except south of the intake scattered bays, where beds on 6 August 1975. Plants were canal and in a few rinsed thoroughly when picked, placed in Velma loam flanks the Radford silt. forming the plastic bags, and stored in a large Flanking these soils and are Tovey and styrofoam ice chest. On the following shoreline of the lake with silt day. each sample was centrifuged in a Bolivia silt loams, Assumption commercial centrifugal extractor to loam dominating south of the intake remove the adherent water (Edwards & canal and in scattered pockets around the Owens 1960), and the fresh weights were lake. soils available for aquatic plant determined to the nearest 0.1 g. Samples The Sangchris are were dried for 24 hours at 105°C in a colonization in Lake large forced-air plant dryer and cooled in Hickory gravelly loam and Bolivia and the plastic bags. Dry weights were determin- Tovey silt loams throughout most of lake, with Velma loam and Assumption ed to the nearest 0.1 g. silt loam south of the intake canal. The soils of the shoreline can have a great LEAF MEASUREMENTS effect upon the aquatic plants offshore. Measurements of N. lutea leaf Not only is the fertility and ease of root or diameters were made along line transects rhizome penetration important, but if the extended perpendicularly from the soils are easily eroded by wave action, the shoreline. Fifty to 100 leaves touching the resulting deposition of the eroded the suitability vertical plane along the transect were material offshore may limit In Lake measured in each plant bed. In early of that area for many plants. spring, when most leaves had not yet Sangchris, shoreline erosion seemed to be of broken the surface, the emergent leaves of great importance in the restriction were counted and categorized as spikes shoreline and submerged vegetation. (leaves still tightly rolled), opening leaves, Soil type variations seemed to have or fully opened leaves. little effect upon the distribution of The significance of these data (0.05 aquatic vascular plants. The area south level) was tested by a oneway analysis of of the intake canal, which had soils variance and the modified new Duncan different from those of the rest of the multiple-range test (Kramer 1956). lake, had a flora similar in type and density to the southernmost portion of the control arm. The low densities of plants INORGANIC ANALYSES in both areas were probably related to Subsamples of P. nodosus leaves, other factors, such as temperature and stems, and roots were ground in a Sorval their upwind isolation from the main Omni-Mixer and stored in glass bottles. portion of the lake and the cooling loop 'Aug. 1981 Moran: Aquatic Macrophytes 397 circulation pattern, restricting seed hampered small boat operation in -transportation and deposition. shallow bays. N. lutea also formed rather impenetrable masses in some bays, but was VEGETATIONAL SURVEYS not regarded as a problem. Potamogeton pectinatus L. (sago pondweed), originally The first vegetational survey of Lake found in 1974, was common but not Sangchris was performed in 1969 abundant. (Limnetics, Inc. 1972), and seven aquatic vascular plant species were recorded In 1976, 23 species were recorded. By (Table 1). The most common species, that time, associations within bays were Najas minor All. (brittle naiad), formed becoming better developed and more an almost continuous bed around the complex. In the first years of this study, shoreline, hmited only in areas of severe from 1971 through 1974. the increase in shoreline erosion and in the extreme diversity occurred in the submerged, southern portions of the intake and floating-leaf, and emergent groups of control arms. Emergent plants were plants, while in 1975 and 1976, the limited to sheltered bays. Nelumbo lutea greatest increase occurred in the plants was recorded in only a few bays, and inhabiting the upper beach areas Potamogeton nutans L.( believed to be P. (wet-soil plants). Two factors may have nodosus) was limited to a small area at been important: (1) as the emergent the junction of the warmwater and plants, and to a limited extent the control arms and near the mouth of the floating-leaf and submerged plants, discharge canal. developed extensive beds, they lessened the impact of waves upon the shoreline, Sagittaria latifolia Willd. (duck and (2) low water levels during 1975 and potato) was abundant along the 1976 removed the effects of waves from shoreline. Typha latifolia L. (cattail) and the beaches, allowing colonization by new .Eleocharis sp. (spike rush) were species. uncommon. After 12 years, only three In 1973, N. minor was recorded from submerged-leaf plants (hyphydates) ;only four sites, but P. nodosus had have been described in Lake Sangchris, extended its range considerably. N. lutea Ceratophyllum demersum L. (submerged had spread to several new sites, and hornwort), Najas minor, and Eleocharis sp. had become quite common Potamogeton pectinatus. Light is a major along the shoreline. In all, 12 species factor controlling the zonation and were recorded. The five additional distribution of hyphydates, none of which species usually occurred in close descends to depths with less than 2 proximity to established plant beds, such percent of the surface light remaining as those of P. nodosus, probably (Hutchinson 1975). Since in Lake indicating that these were areas of stable Sangchris the 1 -percent compensation shoreline sheltered from current and point typically occurs at between 2 and 3 wind-generated waves. m (Moran 1976), it is reasonable to In 1974, 14 species were reported. By expect no vascular plants below 2.5 or 3 this time, some bays in the discharge arm m. and the southern extreme of the control It is interesting to note that the three arm were beginning to develop vascular hyphydates in Lake Sangchris all have a plant communities or associations. P. I myriophyllid type of leaf (deeply 'nodosus had colonized the entire lake, dissected and very thin), thought to be a and extensive N. lutea was establishing deep-water adaptation to increase the beds in the bays of the cooling loop. surface area of a leaf and, therefore, to In 1975, 18 species were recorded increase net photosynthesis in low-light from Lake Sangchris. The only reported habitats. The absence of broadleaf nuisance species was N. minor, which hyphydates in Lake Sangchris is another was abundant again and sometimes indication of the limited photic zone. 398 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 :3 3 s C ^.i a. g 3 g l"!l-2 E -o .a £ u^ *- o See" 3 !^ !U O O C3 33 o g E 5 E E E -I 2 -c 3 S- a. CO h. cq Q, O g •2 c 3 e S 3 S E ^-S -o E * u :^2 o :§ e fe § 1- U o 3 S C3 K = 3 sp "S 2 be 3 o S "5 -a. 4* fc Q S S .2 *^ 3 -s O O ^ o S C3 £ E E E <^ a ^g :g !? -0.-2 <2 c o. ^ a. ^:^ a a|£ " ^° 3 <3 ^ d 3 o ~ fc 5 o o 3 -S a o a. » E o o o a o ^ 3 = S S E ^ E 2 2 a ^ .a a o c» .a o U3 CO ^ cq Q, U ^ a. a c .2 'S. E S" el o 3 .g a I 3 S ? 5 o e-E 3:5; Q CO a, CO r-- ^ cq a, O CO (3 ^;2 a. «i ra •B S Q. ^ 3 E 2 a a il" < CO c-H = 5- a. h Aug. 1981 Moran: Aquatic Macrophytes 399 Another group of plants are the wind and wave action and usually occur floating-leaf plants (ephydates) that grow in bays. Four of these, Lophotocarpus in the sediments but have at (Sagittaria) rooted calycinus (Engelm.) J. G. Sm. least some leaves floating on the water (arrowhead), Nelumbo lutea, Sagittaria surface with one leaf surface exposed to latifolia, and Typha latifolia (cattail), the atmosphere. These plants are make up a major portion of the aquatic somewhat sensitive to current and wave vegetation in Lake Sangchris and provide action and are usually found in protected valuable food and habitat for wildlife. areas. Only two plants of this group have The wet-soil plants, the most diverse been described in Lake Sangchris, group in Lake Sangchris. are those plants Bacopa rotundifolia (Michx.) Wettst. inhabiting the mud banks and beach (water hyssop) and Potamogeton areas. In 1974, only two species were nodosus. In the ephydates it has been reported. By 1976, 12 taxa were present noted that those plants with smaller ovate (Table 1 ). This group of plants seemed to or lanceolate floating leaves are benefit from low water levels that commonly found in areas of more surface increased the available habitat and disturbance than are plants with larger decreased the stress of wave action. Once rounded leaves (Hutchinson 1975). The established, most such plants can tolerate vulnerability of Lake Sangchris to shallow inundation. Wet-soil plants wind-generated waves may be a factor often have rhizomatous growth habits in limiting the colonization of plants of and may prove valuable in decreasing this group. shoreline erosion. Plants such as The emergent plants (hyperhydates) Ammannia coccinea Tothb.; Eleocharis are rooted in the sediments but have a cf. acicularis (L.) Roem & Schultes; E. substantial portion of the vegetation obtusa (Willd.) Schultes; E. smallii Britt. above the water surface. Three such (spike rushes); and Scirpus validus Vahl. species were recorded in 1971 and six (soft stem bulrush) have demonstrated species in 1973, and that number has their abilities to maintain themselves and remained stable to date. All share a spread once they have become established common requirement of shelter from in Lake Sangchris. These plants and the l! American lotus (Nelumbo lutea) in the middle (discharge) arm of Lake Sangchris. I Bllletin Vol. 32. Art. -1 400 Illinois Natural History Survey applied to the data emergents may play a significant role in This formula, the lower curve in Fig. 2, reducing shoreline erosion in the years to describing the equilibrium level will come. indicated that be about 28 species of aquatic vascular this number should be VEGETATION DEVELOPMENT plants and that 1]I reached in about 21 years (1985). This three plant species have Twenty- number agrees with the range (20-34 Lake Sangchris in 12 years, accrued in species of aquatic vascular plants) of accrual seems to describe and the rate reported for a wide variety of lakes by of an S-shaped or logistic curve a portion Beard (1973), Clevis (1971), Judd & expressions were applied to (Fig. 2). Two Taub (1973), Modlin (1970). Nichols & to estimate the maximum the data Mori (1971), and Seddon (1972). species that might be number of To verify the time period, the Sangchris and when established in Lake equilibrium number of 28 species was would be attained. A that number applied to an expression of a decreasing of the maximum number of prediction rate of increase, kd, as given by Metcalf & accrue (equilibrium number) species to Eddy (1972), which predicts the length of the formula for a logistic was based upon time required to reach any given Eddy (1972). curve given by Metcalf & maximum population: = kd(S-P) bt ^ 1 + me dl S-P2 P2) (saturation ^PpPiPa- Pl2(Po + -In = S-Pl population) kd = - P0P2 Pl^ t2-tl where s-Pq S= maximum population b (a constant) = Pq P| P2 = populations at times t] and t2 I The resulting curve (Fig. 3) shows good 1 Po Fig. 2. — Number of aquatic vascular plant species in Lake Sangchris. 1964-1976, and a logistic 28 projection of the maximum number of species to become RESERVOIRS = 4 TEXAS establisheci there compared (Harris S Silvey 1940) with those in four Texas = LAKE SANGCHRIS, 1964 - 1976 reservoirs. = PROJECTION BASED UPON A LOGISTIC CURVE 20 30 W TIME IN YEARS Aug. 1981 Moran: Aquatic Macrophytes 401 50- — r 402 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 1976 C — — •• Fig. 4 — Distribution of Nelumbo lutea within the 1971) 1^ cooling loop of Lake Sangchris. each dot • a representing a documented 1973 C plant bed. 1971 C UJ 40- WARMEST LOTUS BED (£ Y = 0.897X + 6.0^ a: UJ Q. 30 UJ a: UJ I- Fig, 5. — Linear regressions of water temperature for 20 (C) the warmest and coolest z Nelumbo lutea beds against < ambient (Station 1) water UJ temperature. o 10- UJ ffi 3CO 0- COOLEST LOTUS BED -Y=0.973X + 0.75 —I — 10 20 30 MEAN WATER TEMPERATURE (STATION I) Water temperature data (Brigham Y intercept would then describe the 1977) showed that stations 1 and 7 were relationship between water temperatures the coolest stations and both were areas at the plant distribution limits and the devoid of lotus. Brigham's (1975) linear water temperature at Station 1 (Fig. 5). regressions of water temperatures at each The cold-water bed was 0.75°C warmer station against that at Station 1 were used than ambient and the warmwater bed to estimate the water temperature was G.CC warmer than the Station 1 regressions for the high and low temperature. The warmwater bed was temperature distribution limits of lotus. about 2°C cooler than the discharge It was assumed that the regression lines canal. would parallel that of the nearest water The overall thermal regimes at the chemistry station given by Brigham. The distribution limits of N. lutea are r r Aug. 1981 Moran: Aquatic Macrophytes 1();5 Fig 6 — Log normal probability distributions of water temperature (C) at the warmest and coolest Nelumbo lutea beds in the cooling loop of Lake Sangchris, September 1973-July 1976 I -\—— 1— T 1 30 40 50 60 70 eo es 90 9S 96 PERCENTAGE described by log normal probability growing season to investigate the effects curves of water temperature (October upon growth of the temperature regimes 1973-July 1976), shown in Fig. 6. The within the cooling loop. On 28 April 1976 cold-water limit was based upon water nine lotus beds were examined for the temperature data from stations 1 and 2, presence of leaves and their stage of bracketing the coolest plant bed, and the development (Table 2 and Fig. 7). The warmwater limit from stations 4 and B, plants clearly presented a gradient of bracketing the warmest plant bed. The development around the cooling loop. No thermal regimes (0.95 probability) were leaf spikes (leaf blades tightly rolled 2.2° — 28.0»C for the cold-water limit around the petioles) were breaking the and 6.2''-37.6»C for the warmwater surface at plant bed L9 in the coldest limit. Since several of the plant beds area. A great many spikes were up at experienced ice cover during the winter, plant bed L6, with 13 percent of them the lower temperatures are probably of beginning to open. Plant beds L3, L2. no importance. and LI in the discharge arm had 22 24 fully Also, since the warmwater beds were percent of the petioles supporting leaves. occasionally exposed to temperature opened, but immature, leaf-blade diameters extremes in excess of 37.6''C (Brigham In May 1976 stations in the intake 1977), transient high temperatures were were determined at in the main body of undoubtedly tolerated also. Thus, the arm (plant bed L8), in the regimes rather than the extremes are the lake (plant bed L4), and (plant bed L2) (Table 3). suspected to be the determining factor. discharge arm leaf diameter at the L2 bed In Lake Sangchris N. lutea seems to The mean greater than require temperatures about 0.75"'C (27.72 cm) was significantly leaves from beds L4 and L8 warmer than ambient and with a thermal those of regime generally not exceeding 37.6°C (17.96 and 18.70 cm. respectively). for more than 2.5 percent of the growing On 4 August 1976 the mean leaf- season. In 1975 lotus beds were observed blade diameters were determined at seven L9. at the mouth of the discharge canal and beds, LI . L2, L3. L4, L6, L8, and An south of the intake canal (Frakes & analysis of these data indicated that Moran 1975), but neither became stations L6, L8, and L9 (in the intake established. Water temperature regime arm) and LI (the closest bed to the was evidently the principal cause of discharge canal) had leaves of similar failure. size, 42.33-44.08 cm (no significant N. lutea was studied during the 1976 difference). Mean leaf diameters at 404 II I INOIS NaTI RAl UlSroRV Si RVFV Bl LLKTIN' \'ol. 32. Art. 4 Table 2 —Nelumbo lutea leaf development in Lake Sangchris. 28 April 1976 Aug. 1981 Moran: Aquatic Macrophytes 405 E 00 ^ on ,::, 0) Q. E a S E o ^ ' oO o 6 2: »;rS (M r^s°§£, °° E E to o T3 c (0 20) a. < < 406 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 ultimate leaf size was not adversely On 6 August 1975 biomass samples of affected. The smaller final leaf sizes at N. lutea were collected from three areas stations L2 and L3 may indicate an of Lake Sangchris, the discharge arm, the inhibitory effect of the warmer water intake arm, and the main body of the upon ultimate leaf size. The large leaves lake (Table 4, Fig. 8). The lowest mean at Station LI suggest that these plants biomass, 275.2 g/m^, was recorded from were of a different ecotype. the plant bed in the main body of the CONTROL ARM Potamogeton nodosus 1975 A Nelumbo lutea 1975 INTAKE ARM Potamogeton nodosus 1974 vJ MAIN BODY DISCHARGE ARM Fig. 8. —Sampling sites (or Nelumbo lutea and Potamogeton nodosus bionnass estimations in Lake Sangchris, 1974-1975. Aug. 1981 Moran: Aquatic Macrophytes 407 lake, Station L4. This again was probably three arms and northward to the dam. By the result of stress by the wind and wave 1976 it had occupied the entire cooling action in the area. The highest loop and control arm. The most biomasses, 411.7 and 798.0 g/m2 were important factor in the spread of P. recorded from Station L2 in the nodosus in Lake Sangchris appeared to discharge canal. In the intake arm, be the currents in the cooling loop. stations L7, LB, and L9, the mean In Lake Sangchris, P. nodosus has biomass of 303.5 g/m^ was only 50 shown some morphological and percent of that of the discharge arm. physiological variations in response to the microclimatic variations within the lake. POTAMOGETON NODOSUS Growth rates in most of the lake appeared IN LAKE SANGCHRIS similar, but were accelerated in the Potamogeton nodosus is common in southern (warmest) reaches of the Lake Sangchris, with a lakewide discharge arm. On 28 April 1976, a bed distribution in depths of 2 m or less. It is at the mouth of the discharge canal was considered an alkophile, usually producing flower spikes, while a bed at occurring in water with a pH range of the end of the discharge arm (about 400 7.3-8.8 and alkalinities of 49-380 mg m north of Station 4) had only a few HCO3/I (Moyle 1945). In 1971 P. leaves breaking the surface, and plants in nodosus was chiefly confined to a rather the rest of the lake had not yet reached small area south of Station A (Fig. 9). In the surface. By 26 May 1976 plants in the 1973 it extended southward down all discharge canal had set fruit, while plants 1971-1976. Fig. 9 —Distribution of Potamogeton nodosus in Lake Sangchris. 408 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 400 m downstream and in the control flowers of Nymphaea odorata to contain arm were just sending up flower spikes. as much as 1,730 ppm of aluminum. In 1974 and 1975 biomass In Lake Sangchris the mean boron determinations were made in the concentration of the roots (104 ppm) was discharge, intake, and control arms and sigfnificantly higher than that in the the main lake body (Fig. 8 and Table 4). leaves (51 ppm) and stems (50 ppm). The mean biomass of P. nodosus stands These values are similar to the 53-157 increased from 173.9 g/m2 in 1974 to ppm that Hiltibran found in three species 263.3 g/m2 in 1975. In 1975 stands in the of Potamogeton (unpublished data. control arm had the lowest mean biomass Illinois Natural History Survey)- The (214.8 g/m2), while the intake arm highest mean boron concentrations were stands had the highest (336.6 g/m2). in plants from the discharge arm. Since these two areas have similar Calcium is an element that often thermal regimes, it is believed the precipitates during the photosynthetic biom,ass of P. nodosus beds was not bicarbonate in hard waters. affected by temperature. uptake of Thus, some very high concentrations may be obtained in the photosynthetic tissues. INORGANIC ANALYSES Calcium concentrations in the leaves (2.69 percent) and stems (2.76 percent) In 1975 leaves, stems, and roots of P. were significantly higher than they were nodosus were analyzed to determine the in the roots (1.22 percent). These values concentrations of 12 elements: are generally lower than those reported aluminum, boron, calcium, copper, iron, by Riemer & Toth (1968) and are magnesium, manganese, phosphorus, probably related to differences in the potassium, silicon, sodium, and zinc. hardness of the waters involved. Plants Concentrations of these elements in the from the control arm had the highest tissues of plants from various areas of the calcium concentration. lake were compared to determine In Lake Sangchris plants the mean whether any relationship existed between copper concentration ranged from 18 them and location within the lake (Table ppm in the stems to 26 ppm in the leaves 5). and 30 ppm in the roots. Hutchinson The water content of P. nodosus in (1975) presented data indicating 29 ppm both 1974 and 1975 averaged about 81 to be .typical for aquatic plants. The percent. The inorganic ash content of the discharge-arm and main-lakebody dry matter was more than 15 percent of plants had the highest mean the dry weight. Straskraba (1968) concentrations of copper. Smith & summarized the available data on Anderson (1977) also found the highest aquatic plants and arrived at similar copper concentration in P. nodosus from mean values for floating leaf plants, 82 the discharge arm. percent of fresh weight as water and 16 percent of dry weight as ash. In Lake Sangchris mean iron Aluminum concentrations in the concentrations ranged from more than leaves, stems, and roots were all similar, 2,500 ppm in the leaves to more than (1,402-1,756 ppm), but concentrations in 1 1 ,400 ppm in the roots. These values are plants from the cooling loop were higher than those obtained by Hiltibran significantly higher than those in plants (unpublished data. Illinois Natural from the control arm. Plants from the History Survey) but similar to those of discharge arm of the cooling loop had Riemer & Toth (1968). who believed that the highest aluminum concentrations. such high iron concentrations were due to Hutchinson (1943) gave 200 ppm as a a fine precipitate adhering to plant tissues typical value for terrestrial plants and and not removed during washing. Bowen (1966) cited 500 as the best Hutchinson (1975) reported the mean general value. Cowgill (1973) reported value of 0.3 percent (3,000 ppm). similar Aug, 1981 Moran: Aquatic Macrophytes 409 0. 410 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 to the leaf and stem data from Lake plants from the main body area had the Sangchris. highest overall concentration (2.52 percent). Because of magnesium's relation to chlorophyll and photosynthesis, it is not Silicon levels were in excess of 6.8 surprising that the leaves and stems had percent of dry weight. Cowgill (1973) significantly higher concentrations of reported a range of silicon of from 1,910 magnesium (0.42 and 0.34 percent, to 19,350 ppm (up to 1.9 percent of dry respectively) than the roots (0.15 weight). Scheutte & Alder (1927) found percent). Hutchinson (1975) gave 0.33 Vallisneria americana to contain up to percent as the mean concentration for 2.54 percent silicon. It is possible that the aquatic plants in eastern North America. high silicon levels obtained in the analysis Magnesium concentrations were highest of Lake Sangchris plants have been due in plants from the discharge arm of Lake in part to epiphytic diatoms not Sangchris. Gauch (1972) reported that completely removed by the rinsing magnesium requirements for the reaction process. sequence in carbon dioxide fixation Sodium levels in P. nodosus exceeded increase with temperature, which may 6,000 ppm (0.6 percent of dry weight). account for the higher concentrations in Riemer & Toth (1968 and 1969) and discharge-arm plants. Hiltibran (unpublished material, Illinois Manganese concentrations were Natural History Survey) found similar or significantly higher in the roots (577 lower levels in several species of ppm) than in the leaves (233 ppm) or Potamogeton. The mean sodium stems (424 ppm). These values are higher concentration for aquatic plants from than the 52-118 ppm found by Hiltibran various areas of eastern North America is (unpublished material, Illinois Natural about 0.10 percent (Hutchinson 1975). History Survey) but are much lower than In Lake Sangchris mean the for eastern North America, mean concentrations of zinc ranged from 42 2,000 (Hutchinson 1975). Manganese ppm ppm in the leaves and stems to 44 ppm in concentrations were highest in plants the roots. Plants from the cooling loop from the discharge arm. had significantly higher concentrations of In Lake Sangchris plants the mean zinc than plants from the control arm concentration of phosphorus in the roots had. The highest mean concentration of (0.46 percent) was significantly greater zinc was in plants from the discharge than those in the leaves (0.36 percent) or arm. Smith & Anderson (1977) also stems (0.32 percent). The concentration reported zinc concentrations to be of phosphorus in plants from the cooling significantly higher in P. nodosus from loop was significantly higher than that in the discharge arm. plants from the control arm, with the Of the 12 elements examined, 3 (iron, discharge-arm plants having the highest silicon, and sodium) were usually present concentrations of phosphorus. Riemer & in amounts exceeding the capacity of the Toth (1968) found the mean phosphorus analysis. Two elements, calcium and concentration of 56 aquatic plants in magnesium, were significantly higher in New Jersey to be 0.45 percent, with a the stems and leaves than in the roots. range of 0.16-1.87 percent. Three elements, boron, manganese, and phosphorus, were present in the roots in Hutchinson (1975) reported a mean significantly higher concentrations than potassium concentration for eastern in the stems and leaves. Five other North American aquatic plants of about elements, aluminum, copper, iron, 2.6 percent dry weight, similar to those of potassium, and zinc, also had their terrestrial plants. In Lake Sangchris the highest concentrations in the roots. mean value was about 2.3 percent. The roots had the highest mean concentration Plants from the discharge arm of the (2.52 percent), and within the lake. cooling loop had the highest Aug. 1981 Moran: Aquatic Macrophytes 411 concentration of aluminum, boron, nodosus did not appear to be related to copper, magnesium, manganese, temperature in Lake Sangchris, but phosphorus, and zinc. Three of these plants in the warmest portions of the elements, aluminum, phosphorus, and cooling loop began growth and set fruit zinc, were present in significantly higher earlier than did plants in cooler areas of concentrations in plants from the cooling the lake. Mean stand biomass increased loop than they were in plants from the 51 percent (from 173.9 to 263.3 g/m2) control arm. Iron, magnesium, from 1974 to 1975. potassium, and silicon concentrations Inorganic analyses of P. nodosus were also highest in cooling-loop plants. revealed that plants from the discharge Plants from the main lake body had the arm had the highest concentrations of highest concentrations of potassium. aluminum, boron, copper, magnesium, manganese, phosphorus, and zinc. SUMMARY Analyses of the leaves, stems, and roots indicated that the roots had the highest Lake Sangchris is a relatively new concentrations of aluminum, boron, reservoir still undergoing a process of copper, iron, manganese, phosphorus, invasion by aquatic macrophytes. It is potassium, and zinc, while calcium and estimated that the maximum number of magnesium concentrations were higher in species to occur in Lake Sangchris will be the stems and leaves than they were in the about 28, which should be reached when roots. the lake is 21 years old (1985). The species immigration-extinction rate is about 1.9-2.3 species per year. Some literature on Texas reservoirs suggests 50-54 as the maximum number of REFERENCES CITED species. In Lake Sangchris, this number would be achieved by the year 2014. Beard. T. D. 1973. Overwinter drawdown: Impact Establishment and growth of aquatic on the aquatic vegetation in Murphy Flowage, Wisconsin. Wisconsin Department of Natural macrophytes in Lake Sangchris are Resources Technical Bulletin 61. 14 p. limited by the effects of shoreline BowEN. H. J. M. 1966. Trace elements in bio instability and erosion and the chemistry. Academic Press, New York, ix + 241 p. consequent turbidity. As emergent plants Brigham. a. R. 1975. Water quality investigations became established, the increased at Lake Sangchris 5 September 1973 through 16 September 1975. Pages 1.1 -1.100 in Annual stability encouraged further colonization Report for Fiscal Year 1975, Lake Sangchris by other plants. Areas of high shoreline Project. Illinois Natural History Survey. erosion are still barren. Urbana. . 1977. Water quality investigations at Lake Water temperature variations within Sangchris. Pages 1.1-1.5.18 in Annual Report the cooling loop the determined for Fiscal Year 1976, Lake Sangchris Project. distribution of Nelumbo lutea and had Illinois Natural History Survey. Urbana. 1971. Aquatic vascular plant dis a definite effect upon its growth rate. Ci.ovis, J. F. in West •Plants in the discharge arm began growth tribution Cheat Lake (Lake Lynn). Virginia. Castanea 36:153-163. earlier and grew more rapidly than plants Cow(.ii.L. U. M. 1973, The hydrogeochemistry of in the intake arm, but final leaf size was Linsley Pond. U. The chemical composition of greatest in the intake-arm (cool-water) the aquatic macrophyics. Archiv fur plants. Plant biomasses, however, were Hydrobiologie, Supplement, 45:1-119. Dreier, H. 1974. Supplementary study, Lake Sang- gfreatest in the discharge arm. The chris aquatic macrophyte distribution in 1973 occurrence lutea restricted to of N. was and 1974. Pages 1-20 in Annual Report for those areas of the cooling loop with an Fiscal Year 1974, Lake Sangchris Project. annual thermal regime at least 0.75''C Illinois Natural History Survey. Urbana. warmer than ambient water temperature Edwards. R. W., and M. Owens. 1960. The effects of plants on river conditions. \. Summer crops but not exceeding ST.G^C for more than and estimates of net productivity of macrophytes 2.5 percent (9 days) of the year. in a chalk stream. Journal of Ecology The distribution of Potamogeton 48:151-160. 412 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 S. R. T. Moran, R. L. 1977a. Macrophytes. Pages 8.1- Fehrenbacher, J. B.. R. Smith, and Odell. 1950. Christian County soils. University 8.48 in Annual Report for Fiscal Year 1976, of Illinois Agricultural Experiment Station Soil Lake Sangchris Project. Illinois Natural History Report 73. 64 p. Survey, Urbana. Forest, H. S., and E. L. Mills. 1971. Studies on . 19776. Part 2. Phytoplankton dynamics of the plants of the Genesee country (Western New Lake Sangchris. Pages 2.25-2.59 in Annual York State): VI. The aquatic flora of Conesus Report for Fiscal Year 1976. Lake Sangchris Lake. Rochester Academy of Science Project Illinois Natural History Survey, Proceedings 12:110-138. Urbana. influenc- Frakes, M. a., and R. L. Moran. 1975. Lake Movle, J. B. 1945. Some chemical factors Sangchris aquatic macrophyte studies. Pages ing the distribution of aquatic plants in 10.1-10.28 in Annual Report for Fiscal Year Minnesota. American Midland Naturalist 1975, Lake Sangchris Project. Illinois Natural 34:402-420. History Survey, Urbana. Nichols, S. A., and S. Mori. 1971. The littoral Gauch, H. G. 1972. Inorganic plant nutrition. macrophyte vegetation of Lake Wingra. Dowden. Hutchinson & Ross, Inc., Wisconsin Academy of Sciences, Arts and Stroudsburg, PA. 488 p. Letters 59:107-119. Godwin, H. 1923. Dispersal of pond floras. Journal RiEMER, D. N. 1969. A survey of the chemical of Ecology 11:160-143. composition of Potamogeton and Myriophyllum Science 17:219-223. Harris, B. B., and J. KG. Silvey. 1940. Limnolog- in New Jersey. Weed lakes. 1968. survey of the ical investigations on Texas reservoir and S. J. Toth. A Ecological Monographs 10:111-143. chemical composition of aquatic plants in New- Hutchinson, G. E. 1943. The biogeochemistry of Jersey. New Jersey Agricultural Experiment aluminum and of certain related elements. Station Bulletin 820. 14 p. Quarterly Review of Biology 18:1-29. Schuette, H. a., and H. Alder, 1927. Notes on 1975. A treatise on limnology. Vol. Ill, the chemical composition of some of the larger Limnological botany. John Wiley & Sons, New aquatic plants of Lake Mendota. II. Vallisneria York. 660 p. and Potamogeton. Wisconsin Academy of 1973. effects of Letters Transactions JuDD, J. B.. and S. H. Taub. The Sciences, Arts and ecological changes on Buckeye Lake, Ohio, with 23:249-254. emphasis on largemouth bass and aquatic Sculthorpe, C. D. 1967. The biolog>' of aquatic vascular plants. Ohio Biological Survey vascular plants. Edward Arnold Ltd., London. Biological Notes 6. 51 p. 610 p. Kramer, C. Y. 1956. Extension of multiple range Seddon, B. 1972. Aquatic macrophvtes as limno- tests to group means with unequal numbers of logical indicators. Freshwater Biology replications. Biometrics 12:307-310. 2:107-130. LiMNETics, Inc. 1972. A limnological survey of Lake Sangchris, Illinois. Limnetics, Inc.. Smith, K. E., and W. L. Anderson. 1977. Trace at Lake Sangchris. Selected Milwaukee. 247 p. element studies MacArthur, R. H., and E. O. Wilson. 1967. The trace metals in lake sediment, air-borne theory of island biogeography. Princeton particulate matter, and macrophvtes. Pages 5.1- 5.31 in Annual Report for Fiscal Year 1976. University Press, Princeton, N. J. 203 p. Lake Sangchris Project. Illinois Natural Histor\' Metcalf & Eddy, Inc. 1972. Wastewater en- Survey, LIrbana. gineering. Collection, treatment, disposal, McGraw Hill Book Co., New York. 782 p. Straskraba, M, 1968. Der .\nteil der hoheren pfl Modlin, R. F. 1970. Aquatic plant ecolog>' of major anzen an der produktion der stehenden lakes in the Milwaukee River watershed. Gewasser, Internationale Vereinigung fur Wisconsin Department of Natural Resources Theoretische und .\ngewandie Limnologie Research Report 52. 45 p. Mitteilungen 14:212-230, Population Dynamics of the Lalte Sangchris Fishery John A. Tranquilli, Richard Kocher, and John M. McNurney ABSTRACT related to important changes in the reproductive life histories of these species conducted in Lake Surveys were in cooling lakes. During early spring, cooling lake, to Sangchris, a power plant white bass made pronounced upstream determine the effects of thermal spawning migrations into the discharge Generating discharge from Kincaid canal of the power plant, and channel fish and its Station on the community catfish reproduction and recruitment components. From 1974 to 1976 a total of were unusually successful in comparison population 108 catch-per-unit-effort to those of other Illinois reservoirs. six stations samples were collected from Seasonal reversals in fish distribution located in both heated and unheated relative to the thermal effluent were average fish catch (biomass) areas. The documented in this field study. Gizzard species constituted 97.4 was 59.1 kg. Nine shad, yellow bass, and largemouth bass the catch. percent of the total weight of were significantly more abundant in they In order of decreasing abundance, heated areas during cold months and in were carp (33.4 percent), gizzard shad unheated areas during warm months. (23.1 percent), largemouth bass (16.3 The distribution of these species percent), yellow percent), bluegill (7.1 appeared to be the result of behavioral bass (5.3 percent), channel catfish (4.7 thermoregulation. percent), white bass (4.6 percent), black In six cove-rotenone surveys, the bullhead (1.9 percent), and white crappie average standing crop of fishes was 360.9 (1.0 percent). In Lake Sangchris, the kg/ha. Only minor differences in the largemouth bass population has not standing crop of fishes were found within experienced the decline in production the same cove during different seasons commonly observed in unheated Illinois or among coves located in heated and reservoirs as they age. unheated areas. The total standing crop Temporal and spatial distribution of of fish in Lake Sangchris was much the fishes was analyzed by a three-way same as that found in chemically similar analysis of variance model which unheated reservoirs with comparable incorporated year, month, and station total dissolved-solids concentrations. effects. Gizzard shad, blackstripe Gonosomatic indices and gonad topminnows, and freshwater drum were maturity stages showed that largemouth significantly more abundant in heated bass spawning in 1975 and 1977 was than in unheated areas, while the advanced in heated areas by 1 to 3 opposite was true for black bullheads and weeks over that in unheated areas. white suckers. Seasonal aggregations of During 1975, carp spawning apparently white bass and channel catfish in heated began at the same time in all areas of the areas were indicated in significant lake, but in 1976 carp began to spawn station-by-month interactions and were approximately 1 month earlier in heated Dr. John A. Tranquilli is an Associate Aquatic than in unheated areas. A degenerate Biologist. Section of Aquatic Biology. Illinois ovarian condition was seen in Natural History Survey; Richard Kocher is with the approximately 20 percent of the carp Wabash Production Credit Association, Robinson, examined and may have partially Illinois: and John M. McNurney is with R. W. Beck and Company. Denver. Colorado. accounted for the lack of successful This chapter submitted in Jan. 1980. reproduction by that species. Results of 413 414 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 chemical tests on carp tissues indicated accidental chlorination may have been the degenerate ovarian condition was the causative agent. The fish kills had a probably not related to mercury or minimal impact on the fish population. pesticide contamination. Length-frequency distributions were GENERAL INTRODUCTION used to assess the growth of fishes. The Temperature is one of the most carp population was composed almost important environmental factors entirely of large individuals, whereas affecting the biota of an aquatic those of bluegill and yellow bass were ecosystem. In recent years, rapid mostly small, stunted fish. In comparison expansion of the steam-electric power with their growth in other waters, the industry has caused increasing concern growth of carp, gizzard shad, bluegills, for environmental degradation of aquatic and yellow bass was slow, while the habitats. Closed system cooling lakes growth of white bass, largemouth bass, represent a worst-case situation with channel catfish, and freshwater drum was respect to potential alterations of the greater than average. ecosystem by thermal discharges and thus Species-specific weight-length one in which perturbations can be most relationships among heated and readily identified. unheated sites were similar for eight This multifaceted study presents a species of fishes. Significant seasonal detailed description of the results of differences in weight-length regressions several ecological investigations were evident for largemouth bass and regarding the effects of a thermal effluent bluegills. Body condition factors of on the fishes inhabiting a midwestem gizzard shad, yellow bass, and bluegills cooling lake. This study describes (1) collected at bimonthly intervals from species composition, fish distribution, heated unheated stations were and and relative abundance; (2) standing compared. Results indicated that (1) crops; (3) spawning time and throughout the year gizzard shad from reproduction; (4) growth, weight-length unheated areas were in significantly relationships, and body condition better condition than those from heated indices; (5) incidence of parasitism and areas, bluegills from all areas of the (2) disease; and (6) fish kills. Results of lake were in significantly better condition fishery investigations at Lake Sangchris, in July than in November, and (3) in July, along with studies conducted at lower bluegill condition was better in heated trophic levels, have provided one of the than in unheated areas, while the reverse most comprehensive data bases in the was true during November. United States for the evaluation of No gas-bubble disease was observed in cooling lake ecosystem effects. fishes from Lake Sangchris. The incidence of external parasitism and disease for fishes was 0.6 percent in the DESCRIPTION OF THE intake arm and 0.3 percent in the STUDY AREA discharge arm. incidence of internal The Lake Sangchris lies in the north- the intake discharge parasitism in and western corner of Christian County in 30.2 percent, arms was 37.3 and central Illinois approximately 24 km respectively. Heavy internal parasitic southeast of Springfield. The lake is an infestations in bluegills may have artificial impoundment (876 ha) contributed to the stunted growth of that developed between 1964 and 1966 by the population. damming of Clear Creek, a tributary to Three fish kills occurred at Lake the South Fork of the Sangamon River. The Sangchris during 1974, and two of them lake was built to provide cooling water for were related to power plant operations. Commonwealth Edison's 1,232-mega- Examination of dead fishes recovered watt coal-fired Kincaid Gener- from the discharge canal indicated that ating Station. Morphologically, the Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 415 lake consists of three long narrow arms temperatures. The habitat at stations 2 oriented in a north-south direction and and 7 is typical of the lake, with converging at the northern end where the numerous coves and inlets. Station 1, the dam is located (Fig. 1). The power plant intake canal, is a steep-sided channel is located at the southern end of the lake 0.65-km in length. Although the surface between the western and middle arms. waters do not flow into the intake canal, The plant draws water from the west there is a current near the bottom created (intake) arm and empties it into the by circulating water pumps, which middle (discharge) arm. A thermal withdraw water from a depth of 6 m gradient is thus created as the heated below a skimmer wall. Stations 3, 4, and water flows around a 16-km cooling loop. 5, in the discharge arm, represented The east (control) arm is connected to, artifically heated habitats. The discharge but not directly involved in, the cooling canal, Station 5, had the highest loop and thus serves as a control area. temperature of all stations in the cooling This rather unique morphology made loop. The discharge canal is a 1.1 -km Lake Sangchris an ideal site for the study channel with a very obvious current. of thermal effects on aquatic organisms. Station 4, located between the power Fish sampling stations at Lake plant and the dam, is a typical lake Sangchris were selected to represent station characterized by numerous coves, different thermal habitats (Fig. 1). yet it was highly influenced by the Station 7, in the control arm, and stations thermal effluent. The dam area (Station 1 and 2, in the intake arm, represented 3), approximately halfway around the sampling areas with near- ambient water cooling loop, is another habitat STATION 3 STATION 7 PLANT Fig. 1. — Fish sampling stations in Lake Sangchris. 416 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 influenced by the thermal effluent. The January 1974 through November 1976. dam differs from the other stations in The bimonthly fish collections at each that it represents the deepest area of the station consisted of alternating-current lake and is extensively riprapped with electrofishing for 1 hour along approxi- rock along its northern shoreline. The mately 3 km of shoreline (30 minutes slag pond (Water Quality Station 6) is not along each side), seining with a 25-foot a part of the lake and was not a regular (7.6-m) bag seine (two 25-step seine hauls fish sampling station. The slag pond, along each shoreline), and fishing for 24 adjacent to the power plant (Fig. 1), is a hours with a 300-foot (91.5-m) diked 32-ha reservoir, which serves as a experimental gill net (monofilament) settling basin and storage area for the composed of two repeating series of residue of burned coal (slag). Excess 25-foot (7.6-m) panels of six different water is returned from the slag pond to mesh sizes that ranged from 1 .3 to 6.4 cm the lake through a large pipe emptying bar measure (0.5, 1.0, 1.25, 1.50, 2.0, into the discharge canal. Station 1.5 and 2.5 inches). During 1974, electro- (midway between stations 1 and 2) and fishing was conducted after dark, Station 4.5 (midway between stations 4 whereas during 1975 and 1976 the and 5) were sampled to represent the collections were made during the intake and discharge arms, respectively, daylight. The areas of the shoreline whenever supplementary collections for covered while electrofishing at each gonad development, etc., were needed to station are indicated in Fig. 1. During augment the regular bimonthly fish each collection, numerical abundance collections. The supplementary and weights were recorded for all species collections were taken between the of fishes. Species composition, relative regular stations to prevent very intensive abundance, and distribution were sampling efforts from affecting the results determined from these data. These data of the bimonthly quantitative were further analyzed and expressed as collections. catch (kg)/unit effort, percentage composition of the catch, and rank SPECIES COMPOSITION, (biomass) of fishes. RELATIVE ABUNDANCE, AND DISTRIBUTION Bimonthly fisheries population data collected from 1974 to 1976 were analyzed Fish population surveys were using the Statistical Analysis System conducted in Lake Sangchris from 1974 (SAS) (Barr et al. 1976) General Linear to 1976 to describe the composition and Model (GLM) procedure on an IBM structure of the fish community, to 360/75 computer on the University of determine the relative abundance of Illinois campus. A three-way analysis of species within the lake, and to observe variance was performed using a mixed their spatial and temporal distributions model with water temperature at the relative to the thermal effluent. The stations at the time of sampling as a co- distribution and relative abundance of variable; stations were fixed while months fishes in Lake Sangchris were related to and years were assumed random. Data the distribution of fishes in other waters were analyzed by species, using the receiving heated effluents. Contemporary weight (biomass) of the catch for all fisheries data (1975-1977) collected by comparisons, because, unlike the similar methods from nearby unheated numerical catch, it was not believed to be Lake Shelbyville provided a basis for highly affected by annual reproduction. evaluating the abundance of fishes in Since our main interest was to evaluate Lake Sangchris (Tranquilli et al. 19796). the impact of thermal discharge on the fish population, five specific comparisons MATERIALS AND METHODS were made between fish catches at Quantitative fish population samples stations in the intake, discharge, and were collected every other month from control arms. The five contrasts were: I Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 417 (CI) Station 2 vs. 7, a comparison of collected during the study period, their similar stations (habitats) in the intake distribution in the lake appeared to be and control arms; (C2) Station 4 vs. 7, a temperature related^ White suckers were comparison of similar habitats in the collected from all stations except those in discharge and control arms; (C3) Station the discharge arm (stations 4 and 5), 1 vs. 5, a comparison of the intake canal indicating complete avoidance of the with the discharge canal; (C4) stations 1 thermal effluent in all seasons. and 2 vs. 4 and 5, a comparison of the Blackstripe topminnows were not intake arm with the discharge arm; and collected from the intake arm (stations 1 (C5) stations 1, 2, and 7 vs. 3, 4, and 5, a and 2), and although one individual was comparison of all stations in the unheated taken from the control arm, the skewed or near-ambient- water- temperature zones distribution of this species suggested an of the cooling lake with all stations in the attraction for the heated area. thermal zone. The average value of the During the 3 study years, nine species fish catches in November and January constituted 97.4 percent of the total were compared with those in July to test weight of the catch: carp (33.4 percent), for (1) differences in catches during the gizzard shad (23.1 percent), largemouth coldest and warmest months of the year bass (16.3 percent), bluegill (7.1 percent), and (2) interaction with catches at yellow bass (5.3 percent), channel catfish specific heated and unheated stations. (4.7 percent), white bass (4.6 percent), The catches for January and November black bullhead (1.9 percent), and white were averaged to partially account for the crappie (1.0 percent) (Table 2). Carp was reduced efficiency of electrofishing the dominant species, by weight, ranking during cold months. first in biomass each year, followed by In this subsection, statistical signifi- largemouth bass in 1974 and by gizzard cance refers to the P < 0.05 level, shad in 1975 and 1976. The four although higher levels may be indicated piscivorous species in Lake Sangchris in some tables, and catch always refers to (largemouth bass, channel catfish, white weight (biomass) unless numbers are bass, and white crappie) together specifically mentioned. constituted 26.6 percent of the total catch. Although the data are not directly RESULTS AND DISCUSSION comparable, in rotenone collections During the 3 study years (1974-1976), Jenkins (1975) found that predatory game 87,650 fish representing 20 species and fishes constituted 15 percent of the total two hybrids were collected in 108 standing crop in 173 reservoirs of the quantitative collections. A complete list- mid-South. ing of the number and weight of each The average catch per unit effort in species collected (by station and month) is Lake Sangchris (59.1 kg) was only 69 presented in the Appendix (Tables percent as great as that found in Al-18 and Bl-18). A composite species comparable studies at nearby unheated list was compiled to show the distribution of Lake Shelbyville (85.7 kg), but the more fishes at each station in Lake Sangchris diverse fauna and the greater abundance (Table 1). Hornyhead chubs, striped of carp and gizzard shad in Lake shiners, bigmouth shiners, striped x Shelbyville more than accounted for the golden shiner hybrids, and flathead difference (Tranquilli et al. 19796). catfish were uncommon. No endangered Largemouth bass, the most important or threatened species (Smith 1979) were game fish in Lake Sangchris, ranked collected. The distribution of 14 species second or third in biomass during the 3 and the green sunfish x bluegill hybrid study years (Table 2) and constituted could be characterized as ubiquitous from 15.3 to 17.0 percent of the total within the lake, because these species catch. Annual trends in abundance of were collected from all six sampling this species are thus one of the most useful stations. Although only 48 white suckers indicators of the state of the sport fishery. and 105 blackstripe topminnows were Three years of intensive population 418 Illinois Natural History Survey Bulletin Vol . 32 , Art . 4 Table 1 . —Species of fishes collected from six sampling stations at Lake Sangchris between January 1974 and November 1976. Eighteen fish population samples were collected from each station. Station Species Gizzard shad (Dorosoma cepedianum) X X X X X X Carp (CypHnus carpio) X X X X X X Homyhead chub (Nocomis bignttatus) X ...... X . . . Golden shiner (Notemigonus crysoleucas) X X X X X X Striped x golden shiner hybrid ... X ...... Striped shiner (Notropis chrysocephalus) X ...... X X X Bigmouth shiner (Notropis dorsalis) ...... X X Red shiner (Notropis lutrensis) X X X X X X White sucker (Catostomus commersoni) X X X ...... X Black bullhead (Ictalurus melas) X X X X X X Yellow bullhead (Ictalurus natalis) X X X X X X Channel catfish (Ictalurus punctatus) X X X X X X Flathead catflsh (Pylodictis olivaris) ...... X ...... Blackstripe topminnow (Fundulus notatus) ...... X X X X White bass (Morone chrysops) X X X X X X Yellow bass (Morone mississippiensis) X X X X X X Green sunfish (Lepomis cyanellus) X X X X X X Bluegill (Lepomis macrochirus) X X X X X X Bluegill X green sunfish hybrid X X X X X X Largemouth bass (Micropterus salmoides) X X X X X X White crappie (Pomoxis annularis) X X X X X X Freshwater drum (Aplodinotus grunniens) X X X X X X Table 2. —Average annual catch (kg/unit effort), percentage composition of the catch, and rank (biomass) of fish species collected at bimonthly intervals from six Lake Sangchris stations. 1974-1976. Each sample (unit of effort) consisted of 1 hour of alternating-current electrofishing, one (24-hour) experimental gill net set, and four seine hauls. The average catch was calculated from 36 samples each year. The electrofishing portion of the sample was conducted at night during 1974 and during daylight in 1975 and 1976. Aug. 1981 Tranquilu et al. : Fishery Population Dynamics 419 Sampling fishes at Lake Sangchrls with aiternating-current eiectrofishing equipment. surveys demonstrated that the season there, and the stabilizing of water largemouth bass population remained temperature variations that might occur stable at a consistently high level, a as a result of local climatic conditions in a remarkable accomplishment considering cooling lake during the spawning season the abundance oF rough fish (carp and all contributed to the excellent annual gizzard shad) and stunted bluegills. reproduction and growth by largemouth The relatively high catch of bass in Lake Sangchris. largemouth bass in Lake Sangchris, an The average annual catch per unit 11-year-old lake, indicated that the bass effort of all species combined was higher population in this cooling lake did not during 1974 (67.949 kg), when experience the decline in production eiectrofishing was conducted at night, commonly observed in unheated Illinois than during 1975 (49.907 kg) or 1976 reservoirs as they age (Bennett 1951). (59.543 kg), when eiectrofishing was Drew & Tilton (1970) similarly reported conducted during daylight. Significant that two cooling lakes in Texas had variation in the average annual catch remained highly productive over a long among years occurred for three species: period in contrast to the reduction in yellow bullhead, yellow bass, and bluegill game fish populations experienced in (Table 3). For each of these species the unheated Texas reservoirs. They highest catch occurred during 1974 attributed the continued productivity to (Table 2), when the eiectrofishing substantial reduction of stratification in portion of the sample was conducted cooling lakes and improved distribution after dark. This fact was an indication of nutrients. The results of the present that the differences in annual catch may study indicated that although these might have been related to the differential have been contributing factors, the key catchability by eiectrofishing of these element to the maintenance of a species as a result of their behavior during satisfactory hass population in Lake the day and night rather than to a real Sangchris was the beneficial effect of the difference in abundance from year to thermal effluent upon annual repro- year. duction and growth. The earlier spawn in The average monthly catch per unit the discharge arm, the extended growth effort for all species combined (Table 4) 420 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 §B D. O ^ CO i2-g « o c o CO 3 CO E t^ ^ CM O) -^ un w o to ^ 0) c o CO fc o CO o ^ £ & CO Q CO 0) 0) "O ^^ ^to o ^ CO ^ ?^X1 CO (1) CO t £"g o o^E •^ CO 2 o0) CO> 5o «2£ra 2 (u 1" 2 -s -!5 E § £ 2? g ™ < ra " CD CO •^ -^ — ' Aug. 1981 Tranquilu et al. : Fishery Population Dynamics 421 ^ M oO ooiniri'^ooo o o o ^ o o ^ lisu 0-2 'B oooooooo o o o o o o o ^ oO C^ — Oi O "^ — CM 00 *r 'J* (>) o r^ I—' ^D CM Tf to oooooooo ^ o ^ ^ o o ^ O r* ift 00 O 00 ^ oo 0) 422 Illinois Natiral History Si r\kv Bi lletin Vol. 32, Art. 4 Table 4 —Average monthly catch (kg/unit effort) of fishes from Lake Sangchns. 1974-1976 Six stations were sampled in the designated months in each of 3 years, resulting in a total of 18 samples. Each sample (unit of effort) consisted of 1 hour of alternating-current electrofishing. one (24-hour) experimental gill net set, and four seine hauls. Sptnir.s Jan. Mar. Mav Julv Sept. No\. Gizzard shad Aug. 1981 Tranquilli et al.: Fishery Population Dynamics 423 gizzard shad, blackstripe topminnow, (stations 1, 2, and 7) the mean catch of and freshwater drum were greater during white sucker was significantly greater July, while the mean catch of carp was than it was in the heated area because greater during the two colder months this species was not collected from (Table 4). From March to November the stations 4 and 5 (Table 5). For black mean catch of bluegill was fairly bullhead, another species distributed consistent, ranging from 5.6 to 3.8 kg per throughout the lake, the mean catch unit effort, but was exceptionally low (0.8 (1.989 kg) from the intake arm (stations 1 kg) in January. The mean catch of and 2) was significantly greater than the largemouth bass was highest during May mean catch (0.458 kg) from the discharge (16.9 kg), when the fish were engaged in arm (stations 4 and 5). spawning activities near the shore, and The analysis of variance for the catch much lower during extreme temperatures per unit effort data showed significant in January (2.1 kg) and July (6.1 kg). year vs. station interaction for black bull- Analyses of the total catch of all head, yellow bullhead, blackstripe species combined among stations (Table topminnow, and yellow bass (Table 3). 5) revealed that the highest average catch These differences were likely the result of across all months occurred at Station 5 changes during the 3 years in the (69.2 kg) in the discharge canal, and the magnitudes of the catches of these lowest at Station 7 (47.6 kg) in the control species, which were not consistent for arm. When contrasts between specific each station, and/or due to the change stations were tested among species by from night to day electrofishing analysis of variance, no significant dif- collections. ferences were found between the catch at Significant station vs. month stations 2 and 7, or the catch at stations 4 interaction was found for nine species: and 7, station contrasts CI and C2 of gizzard shad, golden shiner, channel Table 3. Analyses of the difference in catfish, blackstripe topminnow, white catch for the ramaining three station con- bass, yellow bass, green sunfish, trasts (C3, C4, and C5) demonstrated largemouth bass, and freshwater drum that gizzard shad, blackstripe (Table 3). Significant differences in the topminnows, and freshwater drum were catch of five of these species (gizzard significantly more abundant in heated shad, blackstripe topminnow, yellow areas, while black bullheads and white bass, largemouth bass, and freshwater suckers were significantly more abundant drum) will be partially explained in in unheated areas (Table 3). The mean subsequent discussions of significant catch (22.2 kg) of gizzard shad at Station interaction between specific heated and 5 in the discharge canal was more than unheated stations during warm and cold twice as large as the mean catch ( 10.0 kg) months. An explanation for the at Station 1 in the intake canal (Table 5). significant station vs. month interaction The mean catch (0.003 kg) of blackstripe was not apparent for two of the minor topminnows was significantly greater in species, green sunfish and golden shiner. the discharge canal (Station 5) than it was However, the significant station vs. in the intake canal (Station 1) because month interaction for white bass and this species was never collected there. channel catfish may be related to Significantly larger mean catches of important biological differences in the freshwater drum were found in the reproductive life histories of these species discharge canal (Station 5), the discharge in a cooling lake in comparison with those arm (stations 4 and 5), and the entire in unheated reservoirs. heated zone (stations 3, 4, and 5) when The significant station vs. month those areas were tested with interaction for the catch of white bass was corresponding unheated areas. In the believed to be related to the unusual intake canal (Station 1), the intake arm spawning behavior of this species in Lake (stations 1 and 2), and the unheated zone Sangchris. White bass were first stocked 424 Illinois Na il rai. Hisidr'i Si KVF/i Bin ki in \<)l. yi. An. 4 in this lake as breeding adults in 1971 and kg) of white bass which occurred in the have since flourished, making an discharge canal (Station 5) during March appreciable contribution to the overall of the 3 study years in comparison with sport fishery (McNurney & Dreier 1981). the mean catches from the other five In large reservoirs, white bass normally stations. The spawning concentration in migrate to headwaters and spawn in the the discharge canal was further flowing water of major tributaries (Webb documented by reproduction studies, & Moss 1968). If major tributaries are which showed that the white bass in the absent, they have been known to spawn discharge canal were in spawning on scattered wind swept points (Bonn condition, and by creel results, which 1953). At nearby Lake Shelbyville, a showed unusually high spring catches mainstream reservoir, upstream from the discharge canal area spawning migrations of white bass were (McNurney & Dreier 1981). In addition, observed in the major tributaries white bass tagged in the discharge canal (Tranquilli et al. 19796). In Lake during the early springs of 1975 and 1976 Sangchris, which has no major were subsequently recaptured from the tributaries, white bass in March and intake and control arms, suggesting that April made pronounced upstream white bass from all areas of the lake were migrations against the artificial current attracted to the flowing water of the created by the power plant to spawn in discharge canal to spawn during early the flowing waters of the discharge canal. spring (Iranquilli et al. 19816). The This is illustrated (Fig. 2) by the well-established white bass population exceptionally high mean catch (20.025 indicates that reproduction in the discharge canal was advantageous and successful for that species. WHITE BASS MARCH (1974-1976) The significant station vs. month interaction for the catch of channel catfish (Table 3) was apparently the result of high mean catches in the discharge arm (stations 4 and 5) during the months of March and May (Table 6). Creel surveys conducted in 1973 and 1974 (McNurney & Dreier 1981) demonstrated that channel catfish were much more abundant in Lake Sangchris than our catchper-unit-effort data indicate. This GRADIENT ).*INTAKE CONTROL discrepancy probably occurred because channel catfish are highly sensitive to Fig, 2 —Mean catch (kg/unit effort) of white bass at Lake Sangchris during March changes in light intensity and generally (1974-1976), migrate to the surface, where they are Table 6 —The distribution of channel catfish in Lake Sangchris relative to the thermal gradient demonstrated by catch (kg) per unit effort^ from six stations at bimonthly intervals 1974-1976 Aug. 1981 Tranquilli et al. : Fishery Population Dynamics va vulnerable to capture by electrofishing. individual species per unit effort from only at night. Because of this behavioral specific heated and unheated stations pattern, the 24-hour gill net sets during warm (July) and cold (January produced the most consistent, but still and November) months from 1974 to inadequate, catches of channel catfish in 1976 revealed no differences between the our population surveys. As expected, the two lake stations with similar cool water largest biomass of channel catfish was temperatures (stations 2 and 7, contrast collected during 1974 when the CI vs. WC of Table 3). The mean water electrofishing portion of the sample was temperatures were determined for each conducted at night (Table 2). Creel station by measurements taken as the fish surveys (McNurney & Dreier 1981) also were collected (Table 7). Among the supported the hypothesis that channel remaining four contrasts of heated and catfish preferred the thermal effluent, unheated stations in waVm and cold since 65.2 percent of the total number months, one or more significant caught by fishermen during 1973 and interactions were found for each of three 1974 were from the discharge arm and major species (gizzard shad, largemouth 31.0 percent of that number were bass, and yellow bass) and three minor captured there during the summer. species (blackstripe topminnow, red For both In Illinois, channel catfish shiner, and freshwater drum). major and minor species, significant reproduction is normally unsuccessful in the catch per large reservoirs not fed by a major stream interactions indicated that and containing substantial populations of unit effort was not independent of the seasonal and predatory game fish, such as the sampling month and that largemouth bass (personal com- spatial differences existed (Table 3). illustrated (Fig. munication with Illinois Department of These differences were 3) of the Conservation staff). Lake Sangchris was by a change in the magnitude originally stocked with channel catfish in catch and, at least for the major species, response to 1969 on a put-and-take basis, and the demonstrated a behavioral catfish population has since sustained the heated effluent. itself through natural reproduction Among the three minor species, without supplemental stocking. significant interactions between heated A comparison of the mean catch of and unheated stations in warm and cold Table 7— Mean Celsius water temperature (± 1 SD) during fish collections taken in Lake Sangchris from January 1974 to November 1976 Temperatures recorded during the electrofishing, gill netting, and seining portions of the fish collections were used to determine the mean at each sta- tion during each of the 3 years (N = 9). No thermal discharge occurred during September 1976 because Kincaid Generating Station was out of operation. 426 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 20 20 -| LARGEMOUTH BASS LARGEMOUTH BASS HEATED 15- LAKE AREA I 5 (9 ^DISCHARGE (STA 4) CiC ARM - (STA 4 4 5) 1 - I ^J» < UN HEATED " 5 - 7 I I WARM COLD WARM COLD MONTHS " MONTHS I ar-HEATED <^ZONE (STA 3, LARGE- 4&5) MOUTH X BASS u < ^UNHEATED -^ ZONE (STA I, 2 47) I WARM COLD * ) Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 427 - 0. 1 00 RED SHINER NHEATED 10 I YELLOW BASS LAKE AREA DISCHARGE (STA 7) CANAL 0.075- ^STA 5)-^ a 50.050- i. 5 - X u I- oa025- .^-HEATED J> LAKE AREA (STA 4) 0.000 1 1 WARM COLD WARM COLD MONTHS MONTHS - - 1.000- FRESHWATER DRUM Q020 BLACKSTRIPE TOPMINNOW ISCHARGE - a750- ARM 0.0 I 5 (STA 4& 5) ^ DISCHARGE o a CANAL (STA 5)- 5o.5oo- iQO I - X I o o 1- O0.250- INTAKE So 00 5- INTAKE ARM CANAL ^.^— 1)-^ (STA I &2) (STA / 0.000 0.000 I I WARM COLD WARM COLD MONTHS - MONTHS °°'°1 BLACKSTRIPE TOPMINNOW °°' °"1 BLACKSTRIPE TOPMINNOW o ^DISCHARGE ARM •^ (STA 4 & 6) - caoo5- c 0.00 5 o ^HEATED ZONE (STA 3,4 & 5) 4 !i ^ O o INTAKE U NHEATED ARM ZONE (STA I &2)-p> (STA 1,2*7)-^ QOOO ^-^ 0.000- WARM COLD WARM COLD MONTHS — MONTHS - Fig, 3, —Continued efficiently collected in either gill nets or behavioral thermoregulation. For yellow electrofishing samples. bass, seasonal differences in catch-per- Temperature selection is an impor- unit-effort samples were restricted to the tant behavioral response of fishes exposed intake and discharge canals, whereas for to thermal effluents. For three of the largemouth bass and gizzard shad, they major species — yellow bass, gfizzard shad, occurred over a much broader area of the and largemouth bass — the significant lake. interactions (Fig. 3) show that these In July, the mean catch per unit effort species were concentrated in unheated of yellow bass in the discharge canal was areas of the cooling lake during warm 0.015 kg, much lower than the 1.651 kg months and in heated areas during cold mean catch per unit effort from the months. Furthermore, the interactions intake canal. During the colder months suggest that the distribution of these the mean catch in the discharge canal species reversed seasonally as a result of was 8.118 kg, much higher than the 428 Illinois Nati ral History Survey Bulletin Vol. 32. Art. 4 3.385 kg mean catch from the intake is graphically illustrated in Fig. 4. When canal (Fig. 3). This distribution suggests catch-per-unit-effort data during warm that yellow bass avoided the discharge and cold months were tested, significant canal during July when the water interactions were found for all four temperature was 36.5"C but were contrasts between heated and unheated attracted to it during the cold months areas (Table 3). Duringjuly. gizzard shad when it was the warmest area of the lake were more abundant at the unheated lake (Table 7). station, the intake canal, the intake arm, The bimonthly distribution of gizzard and the entire unheated zone. During shad at stations in heated and unheated cold months, gizzard shad were more areas of Lake Sangchris from 1974 to 1976 abundant at the heated lake station, the STATIONS' 5 4 I 7 DISCHARGE INTAKE CONTROL -(THERMAL GRADIENT)' Fig, 4. — Distribution of gizzard shad in Lake Sangchris (1974-1976) in relation to the thermal gradient demonstrated by bimonthly changes in catch-per-unit-ef(ort samples collected from six stations. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 429 discharge canal, the discharge arm, and from 1974 to 1976 in relation to the relative the entire heated zone (Fig. 3). Temper- thermal gradient (Fig. 5). During Janu- ature appeared to be the major factor ary, largemouth bass v^rere concentrated governing the distribution of gizzard in the heated area of the lake. As the lake shad. warmed naturally, the concentration The seasonal distribution of large- shifted along the relative thermal mouth bass in Lake Sangchris was gradient, and by July they were illustrated by plotting the average catch concentrated in unheated areas. When per unit effort during bimonthly periods the lake began to cool naturally in the 5 4 I 7 DISCHARGE INTAKE CONTROL ^(THERMAL GRADIENT)— Fig, 5, — Distribution of largemouth bass in Lake Sangchris (1974-1976) in relation to the thermal gradient demonstrated by bimonthly changes in calch-per-unit-effort samples collected from six stations. 430 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 fall, the concentration of bass began to individual species was found for bluegill, shift back toward the heated areas. golden shiner, and freshwater drum Statistical comparison of these catch-per- (Table 3). The linear regression was unit-effort data between heated and positive for bluegill, a relatively abun- unhealed areas in warm (July) and cold dant species, and demonstrated that each (November and January) months increase in temperature of PC resulted in revealed significant differences for an increased catch of 0.494 kg. More contrasts between (1) the heated and bluegill were captured in warmer water, unhealed lake stations, (2) the discharge because as temperature increased, these and intake arms, and (3) the entire heat- fish tended to move from deeper to more ed zone vs. the entire unhealed zone. In shallow water, where they were more all three of these interactions (Fig. 3), vulnerable to capture, especially by largemouth bass were more abundant in electrofishing. For golden shiner and heated areas during cold months and in freshwater drum the linear regression was unhealed areds during July. negative, indicating for each degree Celsius increase in temperature, there was The bimonthly distribution of a decrease in the catch of 0.042 and 0.133 largemouth bass in Lake Sangchris can be kg, respectively. The negative relation- explained in several ways. Either ships for the latter two species were temperature selection, the distribution of believed to be related to high variability forage fish (gizzard shad), or a combi- in the catch, wtiich occurred because nation of these two factors could account these species were relatively scarce in the for the seasonal shift in concentration of lake, and because the sampling bass. Temperature selection was techniques employed were not efficient considered the major factor because methods of collecting these species. gizzard shad were extremely abundant throughout the lake, and except for Results of field studies regarding the January, there was never a shortage of distribution of fishes near thermal these forage fish at any station. Also, in discharges have generally been reported comparison to the bimonthly distribution as concentrations of fish species in heated of gizzard shad relative to the thermal areas during cold months, avoidance of gradient, the shift in concentration of thermal discharge by heat-sensitive largemouth bass was much more distinct species during warm seasons, and (Fig. 4 and 5). Thus, catch-per-unit- orientation of species in a temperature effort data for largemouth bass indicated gradient according to their individual that a substantial portion of the thermal preferenda. Field effects of this population was moving relatively long type provide a common basis for distances around the cooling loop (16.1 comparison. Experimental data on km) on a seasonal basis to select preferred temperature selection by fishes in water temperatures. Directed movements laboratory studies can also be used for of this magnitude and type have been comparison, as they generally agree well confirmed for individual largemouth bass with field data. Differences between in Lake Sangchris by recaptures of tagged laboratory and field data have often been fish (Tranquilli et ai. 19816) and by related to differences in size or age of the radiotelemetry observations (Tranquilli fish (Ferguson 1958). et al. 1981a). In field situations, widely different In the analysis of variance model for results can often be related to site-specific the fish catch-per-unit-effort data, water variables other than temperature. Some temperature measured at each station at of these are differences in geogfraphic the time of sampling was used as a linear location, riverine or lake environments, covariable. After the effects of years, thermal load, design and location of months, stations, and interactions were intake and discharge structures, water removed, a significant relationship quality, distribution of fish food between water temperature and catch of resources, and faunal composition. I Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 431 Over all 3 years and during all abundant and diverse in tropical regions months, two species in Lake Sangchris, (Pflieger 1975). white suckers and black bullheads, were In contrasts between heated and always more abundant at stations in unheated sites in Lake Sangchris, unhealed zones than in heated. Although freshwater drum were significantly more white suckers were not abundant, their abundant in the discharge canal, the distribution was highly uneven, as no discharge arm, and the entire heated specimens were ever collected from any zone throughout the year. These data heated stations. Stauffer et al. in (1976) a indicated that freshwater drum were field study of temperature selection by attracted to heated effluents and had a fishes in the New River, Glen Lyn, high thermal tolerance, but results of Virginia, collected more than 90 percent other field studies did not support this of the white suckers in water cooler than view. In the Wabash River, Indiana, 23.3''C in 1973 and more than 80 percent Gammon (1973) found that freshwater in water cooler than 21.2°C in 1974, and drum were represented about equally at reported that suckers avoided the heated both heated and reference stations and discharge area when water temperatures reported an upper preferendum of only exceeded 26.7°C. In the lower Connecti- 30°C. In the thermal discharge at Lake cut River, Marcy (1976) captured white Monona, Wisconsin, afternoon body suckers at temperature a maximum of temperatures of freshwater drum were only 19.9°C and found that they avoided 29.5-30. 3»C (Neill & Magnuson 1974). the discharge canal of the Connecticut Since freshwater drum were not Yankee Plant during warm months. abundant in Lake Sangchris and were not In Lake Sangchris, the mean catch of effectively sampled, our data indicating a black bullheads was significantly gfreater definite attraction to the thermal effluent in the intake arm than in the discharge may be biased. arm. Except for temperature, we know of The comparison of fish catches at no difference in the habitats at those heated and unheated sites in Lake stations that would account for this Sangchris also indicated that throughout distribution. A similar effect was found the 3-year study period, gizzard shad by Neill & Magnuson (1974), who were always significantly more abundant reported that subadult black bullheads in the discharge canal than in the intake avoided the thermal discharge area in canal. Statistical significance was found Lake Monona, Wisconsin. Thus for white for this comparison because unusually suckers and black bullhads, our results large catches of gizzard shad occurred in paralled those reported for other heated the discharge canal during cooler waters, indicating that these species are months. However, this conclusion was thermally sensitive and that they avoid inconsistent with the significant thermal discharges. interactions which showed that gizzard shad were more abundant in the heated In this study, during all years and in areas during cold months and in the all months, blackstripe topminnows, unheated areas during freshwater drum, and gizzard shad were July. significantly more abundant in some Other investigators have reported heated areas than they were in concentrations of gizzard shad in thermal comparable unheated areas. The discharge areas. In Thomas Hill distribution of blackstripe topminnows Reservoir, a Missouri cooling lake, Witt was limited to the thermally affected area et al. (1970) reported that gizzard shad of Lake Sangchris. Consequently, they were attracted to the heated discharge were more abundant in the discharge during winter. Coutant (1974) found that canal than in the intake canal. A high during spring, gizzard shad were thermal tolerance might be expected for attracted to heated effluents of the Bull this species, as it is a member of the Run Steam Plant on the Clinch River, Cyprinodontidae, a group most Tennessee, but that they quickly . 432 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 dispersed when heating ceased. In the canal (Station 5) during July, when the Wabash River, Indiana, Gammon (1973) mean water temperature reached 36.5°C noted a marked discrepancy of gizzard (Tables 6 and 7). At Station 4 in the shad distribution in thermal effluents discharge arm, the catfish catch with reference to size and age. He found remained fairly high throughout the an upper thermal preferendum of 30"C summer. The highest mean temperature for fish averaging 240 mm in length, but found at Station 4 was 34.5''C in July. A observed that large numbers of smaller similar seasonal distribution was found by shad averaging 175 mm packed the Dryer & Benson (1957), who reported discharge canal and vacated it only when that both blue catfish (Ictalurus furcatus) the temperature exceeded M^C and channel catfish concentrated in the discharge harbor of the New Johnson- Seasonal concentrations of white bass ville Steam Plant on Kentucky Lake from and channel catfish were revealed in the 15 March through June but had left the analysis of variance model by significant area by July. Gammon (1973) found that station vs. month interactions. These channel catfish preferred the moderately seasonal aggregations were subsequently elevated temperature below a thermal related to important changes in the discharge in the Wabash River, Indiana, reproductive life histories of these species to either the effluent canal or the area in cooling lakes in comparison with those above the plant. in unhealed reservoirs. The distribution of channel catfish in During March, unusally large catches Lake Sangchris can also be related to of white bass occurred in the discharge their thermal preferendum and upper canal (Fig 2). A number of factors, avoidance temperature. In laboratory including increased water temperature, studies. Cherry et al. (1974) found that an abundance of gizzard shad forage, or channel catfish were quite flexible in rapid water currents, could have adjusting to a wide range of temperatures attracted the white bass. The timing of and that when acclimated to 30°C, their the aggregation during early spring and upper avoidance temperature was 35°C. A the active reproductive condition of the field estimate of temperature preference fish jointly indicated that the observed channel catfish of 33.9-35''C was concentration was the result of a for made at New River, Virginia, by Stauffer spawning migration. White bass in large et al. and Gammon (1973) reservoirs normally migrate to (1976), reported an upper preferendum of 32°C headwaters during early spring to spawn in the Wabash River, Indiana. Our data in flowing waters (Webb & Moss 1968). that channel catfish vacated the The rapid current was considered the suggest discharge canal during July because major factor that attracted the white bass 36.5°C was above their upper avoidance to the discharge canal in Lake Sangchris, temperature and that they remained as other headwater spawning areas were abundant at Station 4 because 34.5°C was absent in this cooling lake. Similar their range of temperature spawning concentrations have not been within preference. documented at thermal discharges of rivers or other cooling lakes in the United As mentioned previously, the channel States. Barkley & Perrin (1971) reported catfish population in Lake Sangchris has in that white bass concentrated an sustained itself through natural repro- Catherine, effluent bay of Lake duction since its original stocking. This is Arkansas, during June but felt that they unusual because reproduction by this were attracted by an abundance of species is normally unsuccessful in large threadfin shad (Dorosoma petenense) reservoirs not fed by a major stream and Channel catfish were concentrated at which contain large populations of stations 4 and 5 in the discharge arm of predatory game fish, such as the Lake Sangchris during March and May. largemouth bass. Tranquilli et al. They apparently vacated the discharge (19796) reported that reproduction and Aug. 1981 Tranquilli et al, : Fishery Population Dynamics 433 recruitment by channel catfish were Missouri, Witt et al. (1970) reported relatively more successful in Lake increased catches of gizzard shad and Sangchris than in Lake Shelbyville, a largemouth bass in heated areas during mainstream reservoir. The successful winter. In contrast to these results, recruitment in Lake Sangchris can McNeely & Pearson (1974) found that probably be attributed to the beneficial gizzard shad were rather evenly distrib- effects of the elevated temperature and uted throughout a northeastern Texas artificial current of the cooling loop. Sule cooling lake in all seasons. Gibbons et al. et al. (1979) demonstrated that channel (1972) caught significantly more catfish from the discharge arm of Lake largemouth bass per cast (using fishing Sangchris were more fecund than catfish rods) in the vicinity of the heated effluent of equal size from the intake arm. In in Par Pond, South Carolina, than in the findings that parallel ours, Gammon same area when the effluent was not (1973) reported that due to improved heated. reproductive success populations of Although water temperature measure- flathead catfish (Pylodictis olivaris) and ments were obtained during each fish possibly channel catfish had increased in population survey at Lake Sangchris, affected areas of the thermally Wabash these investigations were not designed to River. Indiana. make a precise determination of field Results of this field study have pro- temperature preferences for each species. vided the first documentation of seasonal However, temperature selection was reversals in fish distribution in the vicinity believed to be the major factor affecting of a thermal discharge over an extended the spatial and temporal distribution of time (3 years). This effect appeared to be most species of fishes in Lake Sangchris. the result of behavioral thermoregulation Integration of field and laboratory results and was most apparent for yellow bass, by Neill & Magnuson (1974) indicated gizzard shad, and largemouth bass. that various species of fishes were These species were significantly more distributed within a thermal discharge abundant in heated areas of Lake area according to their temperature Sangchris during cold months and in preferenda. unhealed areas during warm months. Dynamic seasonal changes in relative The seasonal distribution of these fishes abundance of fishes occurred between in Lake Sangchris was therefore heated and unheated areas of Lake somewhat different from that reported Sangchris. Gizzard shad, yellow bass, and for these same species in other heated largemouth bass were apparently at- waters. tracted to the heated areas during cold months and repelled from them during Neill & Magnuson (1974) reported warm months as a result of behavioral that subadult yellow bass avoided the thermoregulation. Results of this study thermal effluent in Lake Monona, underscore the importance of movement Wisconsin, but that largemouth bass and by fishes as a response to heated effluents adult yellow bass were occasionally or and the need to provide adequate refuge usually concentrated in the discharge areas wherever thermal discharges occur. ' area relative to reference areas. They also noted that these tendencies generally did not reverse from season to season or from ,^ STANDING CROPS day to night. In Lake Arlington, Texas, Rutledge (1975) found no significant Standing crop data determined from differences in relative abundance among rotenone samples in lake coves are one of stations for largemouth bass or between the most useful of all fish inventory [seasons for largemouth bass and gizzard methods used in the United States, fshad, but shad were more abundant in a because they are the most standardized thermal mixing zone than at two heated and thus permit data comparison over a jstations. In Thomas Hill Reservoir, wide geographic range. In addition, 434 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 several models have been formulated between standing crops of fishes in (Ryder 1965; Jenkins 1967 and 1977) for cooling lakes and in other types of the prediction of fish standing crops reservoirs. Standing-crop estimates offish according to various physical and/or in Lake Sangchris were needed to assess chemical measurements of reservoirs. the impact of impingement and While the use of cove samples to entrainment of fishes by the power plant represent populations of an entire intake structure. In addition, an accurate reservoir has limitations, we are following description of the fish population was the recommendations of Hayne et al. obtained by comparing population data (1967), who concluded that the total determined by rotenone sampling with standing crop determined by sampling results from other quantitative fish coves was a reliable estimate. The samples. objectives of our study were to compare seasonal changes in fish biomass within MATERIALS AND METHODS and between individual coves in heated Six standing-crop surveys were and unheated areas and to provide an conducted in Lake Sangchris during the 3 overall estimate of the standing crop of years, 1974—1976. Variance petitions fish in the cooling lake by sampling coves were filed with and approved by the in the intake, discharge, and control Illinois Pollution Control Board, allowing arms. Comparisons of these data with the Illinois Natural History Surs'ey to use Jenkins' (1967 and 1977) models were rotenone for the five standing- crop used to demonstrate the relationship surveys conducted during 1975 and 1976. Sorting, measuring, and weighing fishes collected in cove rotenone samples to determine the standing crop. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 435 Prior to 1975 a variance to do such electrofishing survey was also conducted studies was not required. in the treated cove at the end of the first day to determine whether any fish had Coves ranging in size from 0.43 to 1.7 survived the chemical application. In ha were studied; the average size was 1.1 another standing crop survey, the barrier ha. In 1974, a low concentration (1 ppb) was placed across the bay the evening of antimycin A was applied to a cove in before the chemical application, rather the discharge arm to test its effectiveness than during the morning of the study as as a fisheries management tool for the was the normal practice. Then after dark selective removal of excess numbers of the embayed area was electrofished, and stunted and/or undesirable species. Two a number of bluegill and largemouth bass days after the antimycin A treatment, were marked and returned to the cove as rotenone was applied to eliminate the a test of recovery efficiency and numbers remaining fishes in the cove, thereby of fish that escaped. All standing-crop providing an estimate of the total values were based upon actual numbers standing crop (biomass). Standing crop and weights of fishes retrieved; no surveys were conducted in coves from extrapolations were made to account for both the intake and discharge arms fishes not recovered. during the fall of 1975 and were repeated in those same coves during the spring of The control arm sampled 1976. was RESULTS AND DISCUSSION during the summer of 1976. In the six standing-crop surveys for each rotenone In preparation conducted in Lake Sangchris, the smallest net sample, a block (300 m x 3 m) was standing crop (70.8 kg/ha) was found in placed across the mouth of the cove to the first sample, taken in September serve as a barrier to fish movement. 1974, in a 0.43-ha cove of the discharge Polyethylene sheeting (300 m x 4 m) was arm. Antimycin A was applied before the attached to the block net and to steel rods rotenone to test its effectiveness in into the to isolate the driven mud selectively removing excess numbers of the rest the lake. rotenone from of The small, overabundant, and/or undesirable coves detoxified with embayed were species (bluegills, yellow bass, and gizzard potassium permanganate approximately shad). Results of the treatment were the 6 hours after the introduction of disappointing, because the antimycin A to the kills out rotenone reduce danger of killed only 9.7 percent by number and polyethylene barrier in the lake. The was 3.1 percent by weight of the total to remain in place until bluegills allowed standing crop of all species. Considering survived 48 hours of exposure in live- the species composition of the cove, an boxes placed within the treated area. On effective treatment would have removed the first day of the study, all fishes were approximately 85 percent of the fish by collected, indentified, counted, weighed, number. Since the toxicity of antimycin and measured. Dead fish were collected A is altered by small changes in pH and processed daily until were and no more water temperature (Walker et al. 1964), found (usually 4 or 5 days). After the first the applied concentration of the chemical day, the fish were identified and counted, may have been below the lethal threshold but their weights were calculated from of the target species. fresh weights recorded on the first day of the study. The total standing crop of fishes found in the first survey (70.8 kg/ha) was The effectiveness of the sampling much lower than the 3-year average method was tested during one standing- determined from all six surveys (360.9 crop survey by releasing marked large- kg/ha). Several factors may have mouth bass within the embayed area accounted for this difference: (1) the first immediately prior to the application of survey was conducted in the smallest cove the rotenone. An alternating-current sampled, (2) greater numbers of fish may 436 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 have escaped as a result of the pre- Within rotenone samples collected treatment with antimycin A and the from the same cove in spring and fall, longer time period involved in the study, only minor differences in the weight of and (3) predatory fishes, unaffected by the standing crop were observed. Spring the low level antimycin A treatment, may and fall samples from the 0.8-ha cove in have consumed some of the dead or dying the intake arm were 260 and 308 kg/ha, fishes. respectively, the difference being due to a The next four standing-crop surveys larger weight of carp and yellow bass in were conducted in only two coves; one in the fall. Spring and fall samples from the the discharge and one in the intake arm. 1.5 -ha cove in the discharge arm were The original objective was to study the very similar at 299 and 295 kg/ha, respec- same coves in heated and reference areas tively. Although the weight of the during the fall of 1975 and again during standing crop within each cove was fairly the spring and summer of 1976 to obtain stable during spring and fall, twice as estimates of fish biomass in a cooling lake many fish were found per hectare during ecosystem in three seasons of the year. the fall samples. This difference was most This study was terminated during the evident for gizzard shad and bluegill and summer of 1976 before the last two reflected the effect of reproduction by samples in the series of six were collected, these species during the summer. because the power plant ceased operation A comparison of fish standing crops and there was no thermal discharge for a in the intake and discharge arms (Table 6-week period. Although the ex- 8) revealed a slightly higher average perimental design was altered, this series biomass from the heated cove (297.6 of four rotenone collections still provided kg/ha) than in the unheated cove (284.4 a spring and fall comparison within the kg/ha). The species compositions of the same cove and, perhaps more impor- intake and discharge arm coves were tantly, allowed a comparison of fish quite similar, with one species occurring biomass in the intake and discharge exclusively in each arm. However, the arms. relative abundance of individual species Table 8. —The average standing crop of fishes in the intake and discharge arms of Lake Sangchris, The same cove in each arm was sampled during the fall of 1975 and the spring of 1976. The coves in the intake and discharge arms were 0.8 and 1.5 ha, respectively. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 437 in the two arms was quite different was found by taking the average of all six (Table 8). In the discharge arm, gizzard cove rotenone samples, which included at shad were much more abundant. Carp, least one survey conducted (1) in the yellow bass, bluegills, and freshwater intake, discharge, and control arms, (2) drum were much more abundant in the during the spring, summer, and fall intake arm, but their combined total seasons, (3) in each of 3 years (Table 9). weight was more than offset by the total The 275.3 kg/ha average standing crop weight of gizzard shad from the discharge of gizzard shad was unusually large, arm. accounting for 76.3 percent of the total The sixth rotenone sample was standing crop biomass. In contrast, conducted during the summer of 1976 in clupeids constituted only 46 percent of a 1.7-ha cove in the control arm and the standing crop in 161 reservoirs of the yielded an unusually large standing crop mid-South (Jenkins 1975). The standing of fishes (932.1 kg/ha). In that sample, crop of carp in Lake Sangchris (27.0 gfizzard shad accounted for 809.4 kg/ha kg/ha) Was unusually low in comparison and constituted 86.8 percent of the total to the 112 kg/ ha found in midwestern standing crop. This cove was the largest reservoirs by Carlander (1955), but it was and deepest of any sampled, and the similar to the 25.5 kg/ha standing crop study was conducted during late summer found in reservoirs of the mid-South by when young-of-the-year fish were most Jenkins (1975). The biomass of sport abundant. Since the power plant was out fishes in Lake Sangchris totaled 14.4 of operation for several weeks before this kg/ha, consisting of channel catfish (9.5 cove was sampled, the unusual kg/ha), white bass (0.9 kg/ha), concentration of gizzard shad in this largemouth bass (3.5 kg/ha), and white control-arm cove could not be related to crappie (0.5 kg/ha). When compared the distribution of waste heat in the with the total standing crop, the biomass cooling lake. of sport fishes was also relatively low, The best overall estimate of the constituting only 4.0 percent of the total standing crop of fishes in Lake Sangchris biomass. Jenkins (1975) found that Table 9, —Averages of six standing-crop surveys conducted with rotenone in Lake Sangchris coves, 1974-1976, Coves ranged in size from 0.43 to 1.7 ha. Ranges of values are given in paren- theses. 438 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 predatory sport fishes constituted about determined for Lake Sangchris by mark- 15 percent of the total standing crop in and-recapture estimates during those 2 reservoirs in the mid-South. years was 8.8 kg/ ha, which excluded fish <150 in total length during 1974 Tranquilli et al. (1979a) reported mm and fish <200 in total length during that the average standing crop in Lake mm 1975 (TranquilH et al. 19816). Since Sangchris (360.9 kg/ ha) was lower than smaller fishes were excluded, this that found in nearby unheated Lake extimate was conservative. The standing Shelbyville (449.6 kg/ ha). The lower crop of bass in Sangchris standing crop in the cooling lake was Lake estimated by mark-and-recapture related to a less diverse fauna and a methods kg/ha) was similar to the smaller biomass of gizzard shad and carp. (8.8 10.0 kg/ha average standing crop of bass A comparison of the relative found in reservoirs of the mid-South by abundance of fishes found in catch-per- Jenkins (1975) and was consistent with unit-effort collections made by the use of our quantitative netting and electrofish- experimental gill nets, seines, and ing data, which suggested that this alternating-current electroshocker with cooling lake contained a relatively high the relative abundance of fishes found in bass population. The low average cove rotenone samples showed general standing crop of bass observed in agreement for gizzard shad, but not for rotenone samples (3.5 kg/ha) was carp or largemouth bass. The carp partially explained by the skewed size population of Lake Sangchris consisted distribution of bass in those samples. almost entirely of large individuals, The average weight of the 88 bass collect- which were highly vulnerable to capture ed per hectare was only 39 grams (Table by electrofishing and gill netting. 9), indicating that rotenone samples Consequently, their real abundance was consisted almost entirely of young-of-the- probably overestimated in catch-per- year fishes. The mark-and-recapture unit-effort samples, in which they ranked estimate for the standing crop of large- first in weight and constituted 33 percent mouth bass in Lake Sangchris wSis of the entire catch. In 1976, the standing therefore considered to be more reliable crop of carp in Lake Sangchris was than data obtained in rotenone samples. estimated by mark-and-recapture Apparently, larger bass were able to to methods be 20.1 kg/ha (Tranquilli et escape past the block nets, or the shallow al. 1981a), comparable to the 27.0 kg/ha coves selected for study were not standing crop determined in rotenone preferred habitats for larger bass. samples. Thus for carp, it appeared that rotenone samples gave a better estimate The effectiveness of cove sampling of true abundance than did netting and technique was tested on one occasion by electrofishing. releasing seven marked largemouth bass, Adult largemouth bass were also which had been captured from a found to be highly vulnerable to capture different area, within the embayed cove by electrofishing, and in quantitative immediately before the application of the catch-per-unit-effort collections bass rotenone. All seven fish were recovered. constituted 16.3 percent of the total Electrofishing within this cove after the catch. However, in rotenone samples treatment by rotenone indicated that no largemouth bass constituted only 3.5 fish of any species escaped the toxic effect kg/ha and accounted for only 1 percent of the chemical. In another study, which of the total standing crop. To further tested the effectiveness of the barrier, clarify this discrepancy in relative nine bass and 72 bluegills were captured, abundance, the standing crop of marked, and released in an embayed cove largemouth bass in Lake Sangchris dur- the night before the chemical was ing 1974 and 1975 was estimated by mark- applied; five bass and 52 bluegills were and-recapture methods. The average recovered after the rotenone application, standing crop of largemouth bass a sampling efficiency of 55 and 72 Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 439 percent, respectively. Since the standing- index (dissolved solids in ppm/mean crop surveys were conducted in relatively depth in feet), was applied to Lake shallow coves, where water clarity Sangchris physicochemical data. Using permitted the observation of a substantial 315.5 ppm as the average TDS (Brigham portion of the bottom, we concluded that 1981) and 16.2 feet as the average depth, most unrecovered fishes escaped by this equation predicted a standing crop of passing the barrier. 214.3 kg/ha, a value lower than the 360.9 kg/ ha found in our rotenone Hayne et al. (1967) examined the samples. problem of how well cove samples repre- To reduce variability and increase sent populations of an entire reservoir predictive value, Jenkins (1977) for- and found that young fish were usually, mulated additional regression equations but not always, overestimated in both based on TDS concentrations according numbers and weights, while harvestable to reservoir types. Application of his regression fish were often underestimated. While equation determined from 43 the true abundance of individual species nonhydropower reservoirs, in which was found to be biased in rotenone cove carbonate-bicarbonate ions are samples, the total standing crop dominant, predicted a standing crop of determined by sampling coves was found 383 kg/ha for Lake Sangchris, similar to the value determined by our rotenone to be a reliable estimate. Carlander (1955) samples. it concluded that since the annual rate of As a result, was concluded that the production fish in turnover probably varied less from one of biomass Sangchris, population to another than did the Lake an Illinois cooling lake, standing crop, standing-crop data were is not unlike that to be expected in chemically similar reservoirs probably fairly good estimates of fish unhealed production. with comparable total dissolved solids concentrations. The average biomass of fishes found S in rotenone samples at Lake Sangchris of 360.9 kg/ ha thus represents our best SPAWNING TIME AND estimate of fish standing crop for this REPRODUCTION midwestern cooling lake (Table 9). Witt et al. (1970) reported a lower standing Reproduction by some warmwater crop of 202 kg/ ha for Thomas Hill fish species occurs only once per year Reservoir, a cooling lake in Missouri. The during the spring when extrinsic factors, standing crop in Lake Sangchris was such as photoperiod and temperature, intermediate between the 202 kg/ha induce spawning. Increased water average found in reservoirs of the mid- temperatures in the vicinity of a thermal South by Jenkins (1975) and the 449 discharge could thus alter the kg/ha average found for midwestern reproductive cycle of some fishes that reservoirs by Carlander (1955). inhabit a cooling lake. The primary Jenkins (1967) examined data from objective of this study was to compare the 127 reservoirs across the United States dates of first spawning by largemouth and determined by multiple regression bass, white bass, and carp in heated and unhealed areas Sangchris to analyses that total dissolved solids (TDS) of Lake and were an important variable exerting assess observed and potential effects of effluents the positive influence on fish standing crops heated on reproduction of and harvest. Although the nature of this those species. relationship is not well understood, it is During this investigation we observed apparently related to nutrient loading in some carp an abnormal physiological and has been suggested as a useful condition of the ovaries, which we predictor of fish biomass. As a method of descriptively defined as degenerate. comparison, Jenkins' (1967) model, a Catch-per-unit-effort sampling had also curvilinear regression of the standing revealed a lack of carp recruitment in crop on Ryder's (1965) morphoedaphic Lake Sangchris for several years. Carp 440 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 tissues were subsequently analyzed for Nikolsky (1963) and translated by mercury and pesticide residues in an Bagenal & Braum (1971), where: attempt to determine the cause of the Stage 3, Maturation— Eggs distinguish- degenerate ovarian condition. Other able to the naked eye; a very laboratory and field studies were rapid increase in weight of the conducted to determine whether the lack gonad is in progress. of carp recruitment was related to the Stage 4. Maturity — Sexual products reproductive physiology of the fish or to ripe; gonads have achieved their environmental variables. maximum weight, but the METHODS sexual products are still not extruded when light pressure is applied. The beginning of the spawning period was determined by the stage of gonad Stage 5, Reproduction — Sexual products development. As water temperatures are extruded in response to very increase during the spring, the weight of light pressure on the belly; the the gonad increases relative to the total weight of gonads decreases rapidly the start of weight of the individual fish. The weight from spawning to its completion. of the gonad reaches its peak value just before spawning and declines as gametes Stage 6. Spent Condition —The sexual are expelled. Males usually undergo products have been discharged; sexual maturation and arrive in spawning genital aperture inflamed; areas before the females. Consequently, gonads have the appearance of only data from female fish were used in deflated sacs, the ovaries usually our analysis, because (1) ovaries are much containing a few leftover eggs. larger than testes and changes in gonad These studies were repeated for carp in weight relative to total body weight are 1976 and for largemouth bass in 1977, more pronounced and (2) maturation of using the same techniques but with a female sex products allows a more shorter time interval between sampling accurate determination of the actual time dates. of spawning. Sexually mature largemouth bass, During the 1975 study of fish white bass, and carp were captured by reproductive cycles, a number of female alternating-current electrofishing at carp were found with degenerate ovaries. approximately 3-week intervals during Since these fish were obviously abnormal, the spring of 1975 to determine the effect they were not used in the analysis of of increased water temperatures upon the spawning time. It was hypothesized that time of reproduction. Gonads of fish the abnormal ovarian condition was contamination. from the intake arm (stations 1, 1,5, and associated with mercury 2) were compared with gonads of fish Muscle tissues from carp with normal and analyzed for from the discharge arm (stations 4, 4,5, degenerate ovaries were total mercury according to analytical and 5), The gonads were dissected and weighed to the nearest gram, A methods described by Anderson & Smith gonosomatic index (GSI) was calculated (1977), and expressed as a percentage of body Another hypothesis was formed for weight [(gonad weight/body weight) x testing in 1976 after 3 years of catch-per- 100], Gupta (1975) demonstrated that unit-effort sampling revealed almost no the values of the gonosomatic index and evidence of successful reproduction by the maximum ova diameter follow similar carp. Food-habit studies showed that courses and reach their peaks when the carp were feeding heavily on bottom ovaries are ripe. The ovaries were also organic material; so we hypothesized that subjectively assigned a numerical classi- pesticide residues were being fication indicating their stage of maturity concentrated in carp tissues, causing the according to a scale suggested by degenerate ovarian condition and affect- Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 441 ing the viability of gametes. Consequent- to determine more accurately the time of ly, carp of both sexes and females with first spawning in each area. normal and degenerate ovaries were During 1975, peak mean GSI values collected from both the intake and of largemouth bass (GSI = 7.31) in discharge arms for pesticide analysis. heated areas occured on 8 April at 15°C Gonad, liver, and muscle tissues were and in unheated areas (GSI = 7.58) on 1 examined from 20 fish. Aldrin; dieldrin May at IS^C (Fig. 6). A comparison of chlordane; DDT; o.p'-DDT; p,p'-DDT GSI values with gonad maturity DDD; o,p'-DDE; p.p'DDE; lindane stages (Table suggested that heptachlor; heptachlor-epoxide; and 10) the difference in time of spawning in heated and polychlorinated biphenols (PCB's) were unheated areas in 1975 was somewhat less tested for by the Illinois Natural History than the 3-week interval between Survey Pesticide Laboratory, using gas- samples. In 1977 highest mean GSI values liquid chromatography techniques. For for largemouth bass were found on 13 simplicity, the pesticides, pesticide April in both heated (GSI = 8.58) and degradation products, and PCB's will ambient (GSI = 10.21) areas (Fig. 6) at hereafter be referred to collectively as temperatures of 21° and 16°C, respective- pesticides. ly. Gonad maturity stages recorded on 13 Investigations concerning the lack of April showed that four of six fish from the reproduction by carp continued during heated area were spawning, while none of 1977. A 0.2-ha pond, containing no other the fish from the unheated area were run- fishes, was stocked in early May with ning eggs (Table 10). On 21 April, only three male and five female carp from one of six fish from the unheated area Lake Sangchris to determine whether had begun spawning, whereas three of six reproduction would occur in an environ- from the heated area were running eggs, ment where food was plentiful and and some additional spent females were predation by other fishes was not a factor. captured and returned to the lake. Thus, In a second study during 1977, a pair of although peak GSI values were found on carp observed spawning on 1 1 May in the same date in both areas in 1977, the Lake Sangchris were captured by gonad maturity stages indicated that the electrofishing and taken to the onset of spawning occurred about 8 days laboratory. Carp eggs were stripped into earlier in the heated area. Results for shallow dishes, covered with water, and both years can be summarized by stating manually fertilized with milt from the that in Lake Sangchris elevated male to determine whether normal temperatures in heated areas advanced development to the free-swimming stage the date of largemouth bass spawning by would occur. 1-3 weeks in comparison with that of unheated areas. The water temperatures RESULTS AND DISCUSSION at which largemouth bass began spawning in Lake Sangchris were similar When gonosomatic indices are used to to those reported for this species from determine the time of first spawning by a unheated waters (15.6"-23.9''C) by fish population, the sampling frequency Heidinger (1975). becomes a source of experimental error. The onset of spavvming may have occurred Early spawning of largemouth bass in on, just before, or just after the sampling heated areas of the cooling lake was date on which the peak mean GSI value considered beneficial, as it provided a was observed. The analyses of gonad head start in growth. There was no maturity stages supported the interpre- evidence to suggest that young produced tation that peak GSI values occurred near earlier than normal were out of phase the onset of spawning. The sampling with their natural food resources. Sule et dates on which fish first appeared with al. (1979) also found that there was no ovaries in the reproductive stage (stage 5) difference in the fecundity of largemouth or spent condition (stage 6) were also used bass from heated and unheated areas of 442 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 1975 LARGEMOUTH BASS 7- X 111 a 6- u WATER heated 12 12 15 22 27 temp.oc AMBIENT 4 10 8 18 24 Fig 6 —Gonosomatic in- dices for female iargemouth bass in 1975 and 1977 from - I I 1977 heated and unfieated areas of Lake Sangchris and surface LARGEMOUTH BASS water temperatures on - 10 sampling dates 9 - X u 8 - a 7 - z o 6- 01o oz o 5- 4 - 3 - HEATED AMBIENT r~ — n—MM T I I 7 29 13 21 25 4 II FEB MAR APR MAY WATER HEATED 21 19 21 242321 TEMP.°C AMBIENT 13 9 16 20 18 19 2! Lake Sangchris. Fish which are spawned and their average length increased more early have an advantage over smaller fish than did that of smaller, predominately in intraspecific competition. Sule (1981) insectivorous bass from unheated areas. demonstrated how this advantage was The thermal effluent in Lake exploited in Lake Sangchris. He found Sangchris also benefits Iargemouth bass that when young-of-the-year Iargemouth reproduction by stabilizing water bass from heated areas reached 90 mm in temperature variations which might length, they were able to consume fish, occur as a result of local climatic Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 443 conditions during spawning season. Water mouth bass. Kramer & Smith (1962) temperature is an important factor determined that year class strength was affecting year class strength of large- set after egg deposition and before the • w "f ctj rj* en on 'Tf an — ^^ ^ iD r'- in oj to r^ 00 to iC CO o^ o -f ^D fMIMiC'.DO'. CN —-r — r^r^cooo c-j (M Tf in '^ r^ (x: (X) to uD Tf I— CM 00 CO CN 00 to -r en — r* -f in in in o in in ^o CO ^ ^ ^ rf ^ 0 to !N r^ CO CO c 444 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 young were 2 weeks old. They found a = 14.94), but analysis of gonad maturity major cause of egg mortality was a drop stages showed that 10 of the 22 fish in water temperature during this critical captured on 20 March were already period. In Lake Sangchris, short-term running eggs (Table 10). The discrepancy adverse weather conditions would have between the two methods may have less effect on year class strength because occurred because the congregation of fish (1) there were two separate spawning in the discharge canal was part of a periods from 1 to 3 weeks apart and (2) a spawning migration, and the fish vacated sudden drop in air temperature has little the canal shortly after spawning. No effect on the water temperature in the spent fish were collected in the 20 March discharge arm. Production of consistent or 8 April samples. In 1975, spawning by year classes had undoubtedly been a key white bass apparently began near 20 element in maintaining a satisfactory March at a water temperature of 14°C largemouth bass population in this and continued through 8 April. cooling lake over an extended time. This spawning date compares Results of this study which show favorably with that of Webb & Moss earlier reproduction by largemouth bass (1968), who found that white bass in the heated area differ somewhat from spawning began in mid-March at a water those of Bennett & Gibbons (1975). They temperature of 12"C and lasted for 1-1.5 were unable to demonstrate a difference months at Center Hill Reservoir in in the reproductive cycle of largemouth Tennessee. Spawning by white bass bass between heated and unheated areas probably occurs earlier in Lake Sangchris of Par Pond by using a gonosomatic than in nearby reservoirs because of the index; however, they did find that young- unusual migration to the discharge canal, of-the-year bass in the heated area were where water temperatures are elevated. significantly larger, suggesting that Analysis of gonadal development by reproduction in the thermal area may female carp revealed that peak GSI have been accelerated. Accelerated values occurred on 22 May in heated and gonadal development has been shown by unheated areas in 1975 (Fig. 7). Data on fishes inhabiting other waters warmed by gonad maturity were in agreement and thermal discharges. At Thomas Hill indicated that carp spawning began on Reservoir in Missouri, Witt et al. (1970) 22 May in both heated and unheated reported that a thermal discharge areas at 28" and 24»C, respectively (Table affected the rate of gonad development 10). In 1976, two peaks in gonosomatic and accelerated the time of spawning by indices were found for carp from the largemouth bass. Marcy (1976) found heated area. The first occurred on 30 that ovaries of female brown bullheads April at a temperature of 22°C and the white catfish (Ictalurus nebulosus) and (/. second on 30 June at 29°C (Fig. 7). In the catus) developed unseasonably early unheated area a single peak in the during winter in the discharge canal of a gonosomatic index occurred on 9 June at nuclear power plant on the Connecticut 25°C. Comparison of these data with the River as compared with those of females gonad maturity stages suggested that in overwintering in the cooler waters outside. 1976 carp spawning began in the heated area during the first week of May, In 1975, insufficient numbers of white approximately 1 month earlier than in bass were captured from the intake arm the unheated area. These data also of Lake Sangchris to permit a comparison indicated that during 1976 there was of spawning time between heated and either an extended spawning period in unheated areas. Results of catch-per- the heated area, or two distinct spawning unit-effort sampling suggested that white periods, approximately 2 months apart. bass migrated to the heated area to spawn in the flowing water of the discharge A second spawning by carp in one canal. Peak GSI values were found in fish season is not unusual in North American from the discharge canal on 8 April (GSI waters (Carlander 1969). Shields (1957) — Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 445 20 "1 1975 CARP 14 12 - 10 1 ~I 19 10 MAR Fig. 7, — Gonosomatic in- JUN dices for female carp in 1975 WATER HEATED 12 13 36 and 1976 from heated and TEMP °C AMBIENT 4 10 32 unhealed areas of Lake Sangchris and surface water temperatures on sampling 20 - dates. 446 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 unhealed areas and (2) carp from Lake A total of 117 female carp was Sangchris contained significantly more examined during 1975, and 23 (19.6 eggs than carp of similar sizes from a percent) had degenerate ovaries. nearby unhealed reservoir (Sule et al. Degenerate ovaries occurred in 5 of 55 1979). Since field observations and/or the carp from the heated area and in 18 of 62 examination of gonads confirmed that carp from the unhealed area. The pro- annual spawning by carp occurred in portion of carp with normal and Lake Sangchris, we concluded that degenerate ovaries from the intake and extremely high mortality rates in the discharge arms was compared by chi- vulnerable egg, fry, and fingerling stages square analysis in a 2 x 2 contingency were responsible for the lack of table. Results of this test showed that recruitment. there were significantly more (P < 0.05) carp with degenerate ovaries in the Stable water levels, a characteristic of unhealed area (chi-square = 6.13, 1 df), Lake Sangchris, could be related to the indicating that the abnormal condition poor reproductive success of the carp was not related to the discharge of heated population. Studies by Shields (1957) and water into the lake. Swee & McCrimmon (1966) indicated that fluctuating water levels were a major It was hypothesized that the environmental variable affecting carp degenerate ovarian condition of the carp spawning and the survival of carp eggs. in this cooling lake was related to Carp prefer to spawn in shallow, freshly mercury contamination from the coal inundated, vegetational areas, a type of burned by the Kincaid Generating habitat normally unavailable in Lake Station. During the combustion process, Sangchris. Consequently, carp in Lake mercury is vaporized and distributed Sangchris probably spawned in aquatic through the air to the watershed vegetation, where their eggs encountered surrounding the power plant. Anderson excessively high predation by a large & Smith (1977) found significantly higher population of stunted bluegills. Mraz & concentrations of mercurv in sediments Cooper (1957a and b) found that the from Lake Sangchris deposited after the reproduction of young carp was plant had begun operation in 1967 than surprisingly low in ponds containing bass, in those deposited in earlier years. bluegills, and crappies in comparison Analyses of three carp with normal with that in ponds stocked with carp ovaries and three with degenerate ovaries alone. revealed a mean concentration of total In 1975, an abnormal physiological mercury of 0.194 ppm (range condition in the reproductive organs of 0.126-0.252 ppm) for fish with normal female carp was found during the study ovaries and 0.256 ppni (range of carp reproductive cycles in Lake 0.188-0.375 ppm) for carp with Sangchris. The abnormal condition degenerate ovaries. Mercurs* levels in occurred in large carp, averaging 540 carp with both normal and degenerate . mm in total length and 1.876 kg in ovaries were relatively low, below the 0.5 weight, which should have been sexually ppm tolerance limit established for mature. Since there was no indication of mercury in fish bv the L'. S. Food and the normal process of sex cell maturation Drug Administration. The mean in the ovaries, the condition was concentration of mercury found in carp descriptively defined as degenerate. The with both normal and abnormal ovaries degenerate ovaries consisted of flaccid was. however, slightly higher than that sacs containing gelatinous material and found in seven other species of fishes from loose connective tissue interspersed with a Lake Sangchris by Anderson & Smith few undeveloped eggs. Female carp with (1977), who concluded that some . degenerate ovaries were not emaciated unidentified factor was suppressing I and could not be distinguished from mercury accumulation by the fish. The normal females by external examination. small difference in mercury concentra- Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 447 tions between carp with normal and carp was affecting the viability of gametes. with degenerate ovaries suggested that However, the results of this analysis did mercury contamination was not the cause indicate that the degenerate ovarian of the abnormal condition. During m condition of carp was not related to Mtro incubation of carp eggs, Huckabee pesticide accumulation. & Griffith (1974) found that 3.0 ppm of Mercury and pesticide contamination mercury was the lowest concentration of were thus eliminated by results of mercury that had an effect on hatch- chemical analyses as factors affecting the ability. Although we realize that these degenerate ovarian condition of carp. data are not directly comparable to the The heated effluent was disregarded as much lower concentration of mercury we the causative factor, because carp with found in carp muscle tissue, they do degenerate ovaries were significantly indicate that mercury contamination more abundant in unheated areas. These probably had little effect on the repro- data allowed us to discount a relationship ductive success of carp in Lake Sangchris. between the degenerate ovarian condition Since carp were assumed to be feeding and several variables peculiar to cooling heavily on bottom organic material, we lakes. The age and growth of carp in hypothesized that pesticide residues were Lake Sangchris was then suspected as being concentrated in the carp, causing being the primary factor associated with the degenerate ovarian condition and the degenerate ovarian condition, but the affecting the viability of gametes. Of the fish could not be accurately aged. Annuli 13 pesticides tested for in carp tissues, on carp scales were indistinct and only dieldrin and p,p'-DDE showed any difficult to interpret due to the influence appreciable accumulations, the of the thermal effluent and because carp concentrations of the others all being less growth was apparently very slow. that the detection limit (Table 11). Numerous annuli were present on the Among the three tissues examined, the scales of almost all carp, and there was a greatest pesticide concentration was good possibility that many of these fish usually found in the gonad, with liver were between 10 and 15 years of age. having intermediate levels, and muscle Recaptures of tagged carp indicated having the least residue. In a comparison that some individuals actually lost weight of males and females, there was little over a year's time and that the overall difference between pesticide levels in liver growth of carp was very slow (Tranquilli and muscle tissue, but male gonads et al. 19816). By comparing the growth contained much higher residues than of tagged and untagged carp in a female gonads. In general, normal carp controlled pond environment, Tranquilli (males and females) from the heated et al. (1979c) determined that the tagging areas had slightly higher average procedure had no adverse effect on pesticide concentrations than normal fish growth. From this limited age and growth from unheated areas. Female carp with information, we surmised that carp with degenerate ovaries contained lower levels degenerate ovaries were old individuals of DDE and dieldrin in their tissues than which were not growing and had perhaps did female carp with normal ovaries. passed the peak reproductive age. In the early spring, it seemed likely that some of The pesticide levels found in carp these fish would not have the large energy muscle tissue were quite low, much less reserves required for egg production. than the U. S. Food and Drug Administration limit of 0.3 ppm for Investigations concerning the lack of dieldrin in fish fiesh intended for human successful carp reproduction continued consumption. No comparable data on during 1977, when a pond containing no pesticide residues in carp reproductive other fishes was stocked on 4 May with tissues or their effects on reproduction four male and five female carp from Lake were found; so we could not exclude the Sangchris. On 14 June, more than 6,000 possibility that the level of residues found young-of-the-year carp, ranging in size 448 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 from 25 to 60 mm in total length, were obviously highly successful in this pond, collected in one shoreline seine haul from where food was plentiful and predation the 0,2-ha pond. Reproduction was by other fishes was not a factor. D g Q. O E o o0) Aug. 1981 Tranquilli et al.: Fishery Population Dynamics 449 Eggs stripped from a ripe female carp distributions of the first two year classes captured from Lake Sangchris on 1 1 May with contemporary data gathered from 1977 were fertilized and incubated in the Lake Shelbyville, a nearby unheated laboratory at 26°C. A subsample of the reservoir (Joy & Tranquilli 19796). A eggs from this female (N = 193 eggs) major objective of this study was to gave an in vitro hatchability of 87 present some typical length-frequency percent. Apparently normal development distributions to characterize growth and of these larvae occurred until they to bring together the available growth reached the free-swimming stage, at information for fishes of Lake Sangchris. which time the experiment was Two growth related indices, condition terminated. factors K(TL) and weight-length relation- In summary, the lack of successful ships, are often used by fishery biologists carp reproduction in Lake Sangchris as measures of the relative plumpness or appears to be related to a number of well-being of fishes in particular habitats factors operating concurrently. These and as general growth descriptors. In this include a relatively late spawn by carp in study these growth indices were used to relation to the advanced spawn of other evaluate effects of thermal discharge on species; stable water levels, which were Lake Sangchris fish populations. not conducive to carp spawning success; excessively high predation on eggs and MATERIALS AND METHODS larvae by a stunted bluegill population; and a degenerate ovarian condition Length-frequency distributions for all which apparently prevented spawning species except channel catfish were by approximately 20 percent of the compiled from fish surveys taken in females. September 1976. Fishes were collected by the combination of quantitative methods previously described for fish population GROWTH, WEIGHT-LENGTH samples, including the use of seines, RELATIONSHIPS, AND experimental gill nets, and alternating- CONDITION INDICES current electrofishing. Too few channel catfish were collected by these methods in Growth rates of fishes in Lake Sang- September 1976 to provide a represent- chris were extremely difficult to ative sample; so the length- frequency determine by conventional methods distributions for that species were because (1) the thermal discharge compiled from data from a sample affected annual growth marks on scales collected in a cove by the use of rotenone (TranquiOi et al. 19816), and (2) results on 17 August 1976. The rationale for of fish population surveys (catch- per- presenting length-frequency distributions unit-effort samples), recapture of tagged from September population samples was individuals (Tranquilli et al. 19816), and that catches for most species were observations of fish via radiotelemetry relatively high at that time and young-of- (Tranquilli et al. 1981a) all showed the-year fish were well represented. considerable movement by fishes between The use of length-frequency heated and unhealed areas. Con- distributions as the basis for growth sequently, most of the information assessment of fishes in Lake Sangchris regarding the growth of Lake Sangchris rather than calculated length at each age fishes appears elsewhere as the result of was largely unavoidable. Although independent studies. These specialized several disadvantages of this method were studies included the results of tagging pointed out by Joy & Tranquilli (19796), (Tranquilli et al. 19816, Joy & Tran- including the fact that fish were still quilli 1979a), an analysis of growth by growing in September, frequency juvenile largemouth bass in heated and distributions did provide some basis for unheated areas (Sule 1981), and a the generalized description of growth comparison of length-frequency patterns by the most abundant species. Survey Bulletin Vol. 32, Art. 4 450 Illinois Natural History Those size ranges (total length) Linear least-squares regressions for sample. were for bluegill 100-140 mm, for gizzard evaluation of weight-length relationships shad 160-200 mm, and for yellow bass were computed by regressing log weight Each month we attempted length (mm) (Carlander 100-140 mm. (g) on log total to collect a sample of 25 fish of each 1977) for eight of the more abundant species at each station. species in the lake. The species examined was calculated were carp, gizzard shad, largemouth The condition factor bass, formula given by bass, bluegill, white bass, yellow according to this channel catfish, and freshwater drum. Carlander (1977): The formula used was: K(TL) = weight (grams) x 100,000/ = -t- log TL log wt BO Bl total length (mm)3 intercept and Bl where BO represents the Condition indices were tested and found this type of analysis, the bluegill the slope. In not to be normally distributed for measure of change m slope serves as a and gizzard shad. As a result, power length. For body form relative to total transformations (Box & Cox 1974) were a weighted weight- each species studied, applied to the data prior to statistical was determined from length relationship analyses. With these transformations, as collected in population the all individuals the observed value increased, intervals surveys taken at bimonthly (July, transformed value decreased; therefore, November 1975) from September, and the relationships observed on the trans- stations (Fig. 1). each of the six sampling formed scale were opposite those observ- were weighted by the The regressions ed on the real scale. For ease of involved in number of observations interpretation, however, presentation Bl. all calculating BO and and discussion of condition indices for three species will be in untransformed The intercepts and slopes of these terms. Since the condition index data regressions were tested and found to be were not normally distributed, arithmatic normally distributed, and we assumed means were presented without standard normality of variance. The data were deviations as estimates of variability. then analyzed using the Statistical were analyzed using Analyses System (SAS) General Linear Condition data procedures (Barr et Model (GLM) procedure on an IBM the SAS system GLM 360/75 computer. A 360/75 computer (Barr et al. 1976). A al. 1976) on an IBM of variance was multivariate analysis of variance, which two-way analysis with simultaneously considered the performed using a mixed model, fixed and months assumed relationship between the intercepts and stations being weight- III (estimable hypotheses) slopes, was used to compare the random. Type of squares were used length regressions derived for each regression sums were imbalanced. species. In the statistical model, months because the data were assumed random and stations fixed. The following comparisons among replication Since there was unequal stations were made for each species to test regression among the samples, type III hypotheses about condition indices of fish sums of squares were used. The intercepts from heated and unheated stations: (CI) as least-squares of and slopes were reported Station 1 vs. Station 5, a comparison estimates of the means, which are the intake and discharge canals; (C2) would be expected a arithmatic means that stations 1 and 2 vs. stations 4 and 5, obtained. the if equal replication had been comparison of the intake arm with arm; (C3) stations 1, 2, and 7 Condition factors were calculated for discharge of stations 3, 4, and 5, a comparison bluegill, gizzard shad, and yellow bass. vs. unheated or nearly unheated To reduce variation in fish condition the entire zone with the entire thermally affected values for these species resulting from of the cooling lake; (C4) Station 2 vs. differences in size (age), sex, and state of area a comparison of similar sexual maturity, only males falling within Station 7, habitats in the intake and control arms; a specified size range were included in the Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 451 and (C5) Station 4 vs. Station 7, a mm, which probably represents growth of comparison of similar stations in the age fish (Fig. 9). In a comparison of discharge and control arms. Index values growth by gizzard shad in Lake Sangchris determined for fish in November were and unheated Lake Shelbyville, Joy & compared with those in July to test for (1) Tranquilli (19796) reported little differences in warm and cold months difference in growth at age 0, but found (Kl) and (2) seasonal effects occurring at that in Lake Sangchris growth of age I -t- specific heated and unheated locations. and older shad was slow in relation to their growth in Lake Shelbyville and RESULTS AND DISCUSSION perhaps in relation to their growth in Growth other waters. This fact could be very important, because larger shad are less The Lake Sangchris carp population desirable as forage fish and because the was composed almost entirely of large age of a reservoir is positively correlated individuals (Fig. Results of 8). with shad crops and negatively correlated quantitative fish surveys taken at with sport fish harvest (Jenkins 1967). The bimonthly intervals over a 3-year period possibility that the life span of these revealed that less than 1 percent of the forage fish may be shortened in cooling 1,837 carp collected were less than 260 lakes is suggested as an area worthy of mm in total length. These data showed further investigation. that reproduction by this species was unsuccessful from 1974 to 1976. Despite their uniformly small size Additional information regarding the lack (Fig. 10), yellow bass were one of the most of recruitment by carp is presented in this abundant species in Lake Sangchris. report in the section entitled "Spawning They ranked fifth among all species in Time and Reproduction." An analysis of order of abundance (biomass) and by carp growth based on the recapture of weight constituted 5.2 percent of the total tagged fish indicated that little, if any, catch per unit effort. As depicted in Fig. growth by larger individuals of this 10, the growth of yellow bass was severely species was occurring (Tranquilli et al. limited. Although reproduction by this 19816). species was good, by September only a The length-frequency distribution for single mode was apparent in the length- gizzard shad shows one mode near 90 frequency distribution. In fish population 14-1 CARP 12- >- N=83 g lOH ^ 8H 6- <_> a: 2- 1^ 1 100 200 300 TOTAL LENGTH (mm) Fig. 8. — Length-frequency distribution for 83 carp collected from Lake Sangchris in September 1976. 452 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 GIZZARD SHAD that as a result of food resource partitioning among the various fishes in 15 N=2,612 Lake Sangchris, the relatively small-sized yellow bass were relegated to feeding primarily upon zooplankton throughout their life history rather than switching to g 12 LU fish (a more nutritious food) at larger ^ 10 sizes. This type of niche segregation was suggested as a mechanism which may have suppressed growth and contributed to further stunting of the yellow bass population. M 4 Although comprised of small individuals, the bluegill population in Lake Sangchris ranked fourth in abundance (biomass) and constituted 7.1 percent of the total catch per unit effort by weight. The September length- TOTAL LENGTH (mm) frequency distribution revealed a mode near 50 mm, which apparently reflected Fig. 9 — Length-frequency distribution for 2,612 gizzard shad collected from Lake growth of age fish, and another mode at Sangchris in September 1976. approximately 90 mm, which probably represented growth of age I-i- and older surveys conducted from 1974 to 1976, less fish (Fig. 11). Joy & Tranquilli (19796) than 6 percent of the more than 15,000 concluded that the growth of bluegill at yellow bass collected were larger than 160 age in Lake Sangchris in 1976 was equal mm (6.3 in.). Sule et al. (1981) reported to, but thereafter was probably less than, YELLOW BASS BLUEGILL 16 =1.071 N=1.758 14 TOTAL LENGTH (mm) 100 200 Fig. 10, — Length-frequency distribution of Fig. 11. — Length-frequency distribution for 1 ,071 yellow bass collected from Lake Sangchris 1,758 bluegill collected from Lake Sangchris in in September 1976. September 1976. Aug. 1981 Tran^uilli et al. : Fishery Population Dynamics 453 yellow bass) for limited aquatic insect food resources. The white bass length-frequency distribution (Fig 12) showed a bimodal distribution for age fish, ranging in size from 80 to 190 mm. Another mode at approximately 240 mm represented age I + fish.Joy&Tranquilli (19796) report- ed that in 1975 and 1976 white bass achieved about the same growth to age II in both Lake Sangchris and Lake Shelbyville, and that this growth was TOTAL LENGTH (mm) greater than the average growth for white in other Fig. 12. — Length-frequency distribution for bass waters. The recapture of 14 149 white bass collected from Lake Sangchris in tagged white bass revealed that growth September 1976, was unaffected by movements between the average annual growth of bluegill in heated and unheated areas in Lake Lake Shelbyville and other waters. More Sangchris and that growth was relatively than 20,000 bluegills were captured from rapid (Tranquilli et al. 19816). Lake Sangchris in fish population surveys Age largemouth bass were repre- (1974-1976), and less than 2 percent were sented in the September 1976 length- larger than 160 mm, providing further frequency distribution by fish ranging evidence of the severe stunting of this from 50 to 190 mm (Fig. 13). It was species. Food habit analyses (Sule et al. assumed that fish between 190 and 290 1981) indicated that the stunting of mm represented the gfrowth of age I + bluegills in Lake Sangchris was partially fish. Consistently strong year classes of the result of extensive intra- and inter- largemouth bass were produced in Lake specific competition among large Sangchris; dominant year classes were populations of small fishes (particularly never observed. LARGEMOUTH BASS N=406 100 200 300 400 500 TOTAL LENGTH (mm) Fig. 1 3. — Length-frequency distribution for 406 largemouth bass collected from Lake Sangchris in September 1976 454 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Comparison of length-frequency including Illinois (Carlander 1977). Joy & distributions determined from September Tranquilli (1979a and 19796) suggested 1975 and 1976 samples suggested that that the extended growing season caused largemouth bass growth at ages 0, 1+ , by the heated discharge was the major and II + was more rapid in Lake reason for the greater growth exhibited Sangchris than in Lake Shelbyville (Joy & by largemouth bass in Lake Sangchris in Tranquilli 19796). However, this analysis comparison with their growth in Lake allowed no precise determination of Shelbyville. average annual growth by largemouth Sule (1981) examined the growth of bass in Lake Sangchris which could be young-of-the-year largemouth bass in compared with that in other waters. heated and unheated areas of Lake Therefore, a curve was generated from Sangchris. He found that growth rates of growth data obtained from tagged fish juvenile fish in the two areas were similar recaptured after one growing season (Joy throughout most of the study period. & Tranquilli 1979a). It indicated that in However, at the end of the normal Lake Sangchris bass reached mean growing season fish from the heated area lengths of 121, 274, 358, 411. 444, and continued to grow, whereas those from 465 mm at ages 1 through VI, respective- the unheated area did not. ly. From these data it was determined Annual growth of tagged largemouth that after age I the estimated annual bass in heated and unheated areas of growth of Lake Sangchris largemouth Lake Sangchris was also studied by Joy & bass was more rapid than the average an- Tranquilli (1979a) and was found to be nual growth of the species in Lake significantly greater in heated areas. Shelbyville, other Illinois waters in Estimated lengths at ages I through VI, general (Bennett & Thompson 1939, respectively, were 138, 278, 380, 434, Starrett & Fritz 1965, and Carlander 462, and 477 mm in heated areas and 1977), and waters of the upper Midwest, 100, 260, 325, 378, 415, and 441 mm in >- C2f tJ3 TOTAL LENGTH (mm) Fig. 14. — Length-frequency distribution for 505 channel catfish collected fronn Lake Sangchris in August 1976. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 455 unhealed areas. These growth differences of each regression, showed that there was were attributed to differences in length of no significant difference among stations the growing season in Lake Sangchris, for the weight-length relationship of any which was approximately 245 days in species examined (Table 13). However, heated areas and 194 days in unhealed significant differences were found among areas. months for the bluegill (P < 0.01) and As mentioned earlier, the channel largemouth bass (P < 0.05) regressions. catfish population of Lake Sangchris has While difficult to interpret, these data been able to sustain itself through natural suggested that seasonal variation (avail- reproduction under somewhat unusual ability of food resources or the appear- circumstances since the original stocking. ance and growth of young-of-the-year Age channel catfish were represented in fish in the samples) had more effect on the August 1976 length-frequency weight-length regressions of these species distribution (Fig. 14) by a few fish than the presence of a thermal effluent. ranging in size from 50 to 80 mm, while Working with five of the species age I + fish were represented by the mode examined in this study, Rutledge (1975) occurring at 210 mm. By the comparison found no significant differences in of samples collected in September 1975 calculated weights of condition (derived and 1976, Joy & TranquilH (19796) by weight-length regressions) for seven concluded that the mean length of species of fish captured in heated and channel catfish at age II was slightly unhealed areas of Lake Arlington, greater in Lake Sangchris than in Lake Texas. Bennett (1972) reported that Shelbyville and that the growth of this black crappies {Pomoxis nigromaculatus) species (at least to age II) in Lake from heated areas of a reservoir receiving Sangchris was therefore greater than its a thermal effluent in South Carolina had average growth in other waters. a significantly higher weight-length In September 1976 only 20 freshwater relationship, indicating that the heated drum were collected, and so a water provided a more suitable representative length-frequency environment. distribution was not compiled. From analysis of September 1975 samples, Joy Condition indices & TranquilH (19796) reported that age drum exhibited a bimodal distribution Condition factors were determined ranging from 1 10 to 140 mm and that age for 632 bluegills, 684 gizzard shad, and I + fish were represented by a mode at 294 yellow bass in 1976. Mean condition 200 mm. From this information, they values ranged from 1.481 to 2.001 for concluded that the growth of freshwater bluegills (Table 14), from 0.776 to 1.016 drum to age II was greater in Lake for gizzard shad (Table 15), and from Sangchris than in Lake Shelbyville. 0.986 to 1.204 for yellow bass (Table 16). To assess thermal discharge effects accurately, we reduced variation in Weight-Length Relationships condition values by including only male Weight -length relationships were fish of a given size range (age) in our derived for eight species of fishes samples. Consequently, our condition collected from six sampling stations (Fig values are not directly comparable to 1) located in heated and unhealed areas those found in the literature, which of Lake Sangchris during July, include fish of many sizes and of both September, and November 1975 (Table sexes. 12). As expected, the slopes of the Yellow bass condition factors were regfressions for all eight species were near normally distributed, but power trans- 3.0 (Carlander 1969 and 1977). formations were needed to establish the The multivariate statistical analysis, normality of bluegill and gizzard shad which simultaneously considered the index values. Analysis of variance relationship of the slope and the intercept revealed no difference in condition < 456 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 indices among stations for either bluegill ferent (P < 0.01) among stations. Ad- or yellow bass (Table 17). Gizzard shad ditional contrasts between heated and condition factors were significantly dif- unhealed stations revealed that (1) mean to CO CM CC r^ Tf ^o O X eg — OJ o o CD + •a O CD ra "o Ln - COKcr> ?w to 9 I. B CM 5 " _C0 to I- ID t/D Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 457 Table 13. — Multivariate analysis of variance for weight-length relationship of fishes collected from six Lake Sangchris sampling stations during July. September, and November 1975. Significance at the 0.05 and 0.01 level is in- dicated by 1 and 2 asterisks, respectively. — 458 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 16. Mean coefficient of condition K(TL), of male yellow bass (100-140 mm in total length) collected from Lake Sangchris at bimonthly intervals during 1976. Ttie means are followed by the sample size (in parentheses). Heated (Relative Thermal Gradient) Cool Unheated Lake Sangchris Station Month Jan. 1.141(25) Mar. 1.204(25) 1.122(11) 1.153(19) May 1.143(25) 1.045(16) 1.145(25) 1.018(25) 0.986(24) 1.038(25) July Sept. 1.193(25) Nov. 1.090(25) 1.000(24) (Table 17). For bluegills and gizzard None of the hypotheses we tested shad, July values were significantly {P regarding condition values of gizzard < 0.001) greater than November values. shad at heated and unheated stations Insufficient numbers of yellow bass were during warm and cold months were collected for specific monthly found to be significantly different, how- comparisons. The higher condition ever, and too few yellow bass were factors of bluegills and gizzard shad in collected for detailed analysis. For blue- July were most likely the result of gills, the three comparisons (Kl CI, Kl increased seasonal availability of food C2, Kl C3) between heated and unheated resources for these species. areas in warm and cold months were The analysis of variance (Table 17) significantly different (P < 0.001). In July indicated significant (P < 0.001 or P mean condition values of bluegills were < 0.01) station-by-month interactions for higher in heated than in unheated areas, condition factors of all three species. while the opposite was true during Table 17. —Analysis of variance table for the coefficient of condition, K(TL), of male bluegili, giz- zard shad, and yellow bass captured at bimonthly intervals from six Lake Sangchris stations. Significance at the 0,05, 0.01, and 0,001 level is indicated by 1, 2, and 3 asterisks, respectively: coefficients of determination (r2) are given at the bottom of the table. Source of Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 459 November (Tables 14 and 17). The competitive advantage in size over fish analysis of variance also revealed that from the unheated area as a result of the bluegills collected from two similar extended growing season. habitats (Kl C4) were in unheated From an examination of the literature significantly (P 0.001) better condition < regarding effects of thermal discharges the control arm (Station during in 7) July on condition indices of fishes inhabiting and in the intake arm (Station 2) in thermal effluents, it is apparent that (Table 17). November effects vary widely among species, among The percentage composition of fish of different sizes, and among study aquatic insects in the diets of small blue- sites. greater in gills from Lake Sangchris was Several studies have been conducted August the heated area during July and in Par Pond, a reservoir receiving cool- during and in the unheated area ing water from a nuclear production December (Sule et al. November and reactor in South Carolina. Bennett (1972) insects were one of 1981). Since aquatic reported no difference in condition values bluegill the most important food items in of adult bluegills from heated and differ- diets, we can only surmise that the unheated areas, but found that condition ential use of these organisms had some factors were significantly higher for effect on body condition factors of fish fingerling bluegills from control areas inhabiting the heated and unheated and for adult black crappies from heated stomachs zones. The percentage of empty areas. Bennett & Gibbons (1974) in the samples indicated more frequent examined the growth and condition of feeding by bluegills in heated than in juvenile largemouth bass in Par Pond and unheated areas during July and August found that although bass from the heated feeding (Sule et al. 1981). This frequent area were generally larger and grew may have allowed bluegills in heated significantly faster than young bass from areas to gain weight during midsummer unheated areas, their body condition in spite of higher metabolic factors were generally similar. requirements. Conditon factors of With data compiled over a 10-year bluegills from the heated zone may have period. Gibbons et al. (1978) declined in November in relation to demonstrated that adult largemouth bass those from the unheated zone, because from unheated areas of Par Pond exhibit- even if they continued feeding, their ed significantly higher mean condition maintenance requirements would have factors than those from heated areas and been much higher than in unheated showed that bass with lower body areas. A similar relationship was shown condition values were low in stored by Massengill (1973), who reported that energy reserves. The authors implied that even though brown bullheads {Ictalurxis these findings were evidence of subtle nebulosus) inhabiting a thermal effluent biological effects of thermal pollution fed throughout the winter, their body that might go unnoticed without critical condition was poorer than that of those systematic examination on a long-term found at ambient temperatures in a cove basis. However, the authors fail to point of the Connecticut River. out that Par Pond represents a highly Sule (1981) compared the condition unusual aquatic ecosystem with an ex- factors of young-of-the-year largemouth tremely large bass population resulting bass in heated and unheated areas of from restricted access and a ban on sport Lake Sangchris and found on five of eight fishing. Although standing crop sampling dates that fish from the intake information is apparently unavailable. arm were in significantly better condition Gibbons & Bennett (1973) estimated than those from the discharge arm. largemouth bass density in Par Pond at However, fish from the heated area were 29,000 fish in the vicinity of the cold not in poor condition, and by the end of dam, and 35,000 fish in the vicinity of the the growing season they had gained a hot dam. At these population levels, it is 460 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 not surprising that the body condition of than in November, and that (3) in July largemouth bass was significantly lower mean condition factors of bluegills were in heated regions or that some bass higher in heated than in unheated areas, remained in the heated area throughout while the opposite was true during the year. In Lake Sangchris, which has a November. These differences were more normal largemouth bass population related to the relative abundance and/or density, this species was shown via fish use of fish food resources in heated and j>opulation surveys and by radiotelemetry unheated areas and to greater metabolic observations to be particularly adept at requirements of fishes inhabiting avoiding the thermal discharge areas thermally affected zones. Results of this during the most stressful summer periods. investigation and those of other research- ers regarding fish condition factors in the In a small cooling lake, North Lake, vicinity of thermal effluents show few located in northeastern Texas, the size and similarities between different ecosystems condition of five species of fishes collected and reveal that, except under unusual at the mouth of the effluent canal were circumstances, observed differences not significantly different from those of cannot easily be categorized as either fish collected at other stations in the beneficial or detrimental to the fish reservoir, but condition factors of populations over extended time periods. channel catfish, river carpsucker (Carpwdes carpio), gizzard shad, thread- fin shad, and bluegill were lower than those reported for these species in other INCIDENCE OF PARASITISM parts of the United States (McNeely & AND DISEASE Pearson 1974). The authors suggested well their hosts, that in a small reservoir such as North Fish parasites, as as Lake, the effects of a heated effluent may are affected by changes in water be generalized over the entire body of temperature. Seasonal cylces in the water, particularly when a cool-water abundance of fish parasites are well known and are often associated with refuge area is present beneath the surface stratum. water temperature fluctuations (Rawson & Rogers 1972). Heated effluents Marcy (1976) reported that brown discharged into an artificial cooling lake bullheads and white catfish (Ictalurus could affect fish parasites or disease catus) living in the discharge canal of the organisms directly by causing an increase Connecticut Yankee Plant on the or decrease in their population levels, or Connecticut River during the winter indirectly by making fishes more or less weighed significantly less and were in susceptible to infestation. Our objective significantly poorer condition than those in this study was merely to compare the cooler overwintering areas outside in two incidence of internal and external the canal. In the White River at Peters- parasitism and disease in fishes from burg, Indiana, studies revealed that heated and unheated areas, relating any centrarchids [longear sunfish (Lepomis differences to the effects of water megalotis), spotted bass {Microptervs temperature. A comprehensive investi- punctulatus), bluegill, and white gation of fish parasitism was not crappie] did not have significantly conducted at Lake Sangchris. different condition factors in heated and The incidence and intensity of fish unheated sections (Benda & Proffitt 1974). parasitism in artifically heated reservoirs Our study showed that (1) throughout and streams have been studied by other the year, gizzard shad from unheated investigators, and their results with areas of Lake Sangchris were in signifi- respect to the effects of thermal cantly better condition than those from discharges have been mixed. Smith heated areas, that (2) bluegills and (1971) attributed the high degree of fish gizzard shad from all areas of the lake parasitization that he found in a Texas were in significsindy better condition in July cooling lake to the year-round optimum Aug. 1981 Tranquilli et al.: Fishery Population Dynamics 461 temperatures for parasites. In heated and incidence of fish infestation at stations 1 unhealed areas of the White River, and 2 in the intake arm was compared Indiana, the incidence of fish infestation with that at stations 4 and 5 in the by a parasitic copepod (Lernaea discharge arm. A total of 10 fish cyprinacea) was examined in different collections was taken from each station in years by Benda & Proffitt (1974) and each arm. Fishes were given a cursory Whitaker & Schlueter (1973). Benda & examination for evidence of infestation Proffitt could not relate the variation in by external parasites or disease as they centrarchid infestations they observed in were weighed and measured. Internal 1969 and 1970 to the effect of increased organs (liver, heart, intestine, and heat. In 1971 and 1972, Whitaker & gonads) of fishes dissected for sex Schlueter studied the incidence of determination or for food-habit analyses Lernaea infestation in relation to heated were examined for infestation by internal water for a larger number of fish species parasites. All examinations were made and found that some species were with the unaided eye; internal organs affected positively and some negatively were not dissected and examined under a and that the overall influence was rather microscope to determine whether minor. In Par Pond, near Aiken, South parasites were present. Carolina, Eure & Esch (1974) found that the number of helminth parasites per RESULTS AND DISCUSSION host fish was significantly higher in largemouth bass from the heated areas The kinds of external parasites and compared with those from normal areas. diseases observed among fishes from Lake The intensity of parasitism of Sangchris included protozoans (Ichthyo- mosquitofish {Gambusia a/finis) by two phthirius), parasitic copepods, leeches, strigeid trematodes was studied in a fungi, and a virus (Lymphocystis). These variety of thermally stressed habitats at parasites and diseases are commonly the Savannah River Plant near Aiken, found on fishes in Illinois waters. South Carolina, by Aho et al. (1976). The eight species of fishes studied, the They found that the density of Diplo- numbers of fish examined, and the stomum scheurtngi was higher in fish percentage infested from heated and from unhealed areas, while the density of unheated areas are shown in Table 18. Omithodiplostomum, ptychocheilus was The overall incidence of infestation by higher in fish from heated areas. Hagele external parasites and disease in both the & Tranquilli (1979) found that while intake and discharge arms was very low at there was no difference in the rate of fish 0.6 and 0.3 percent, respectively. The infestation by parasites in the heated and proportion of externally infested fishes unhealed areas of Lake Sangchris, there found in the intake and discharge arms was a significant difference between the was not compared statistically, because unhealed areas of the cooling lake and for most species the test results would, as unhealed Lake Shelbyville, with a result of a large sample size and a low Lake Shelbyville fish having a higher incidence of occurrence, have no bio- infestation rale by monogenetic logical importance. Inspection of the trematodes. data indicated that the incidence of external infestation was similar in both MATERIALS AND METHODS heated and unheated areas for all species, except perhaps in the white crappie. A The incidence of internal and ex- total of 50 white crappie from the ternal parasitism or disease among discharge canal were examined, and 5 Lake Sangchris fishes was studied from (14 percent) were infested, mostly with January 1974 through July 1975. Fishes Lymphocystis disease. From the intake were collected at bimonthly intervals by arm, 84 fish were examined and 2 (2.4 alternating-current electrofishing, ex- percent) were infested, suggesting that perimental gill netting, and seining. The the heated water might have caused an : 462 Illinois Natural History Survey Bulletin Vol.32, Art.4 Table 18. —Species of fishes from the intake and discharge arms of Lal = 9.185, I df), suggesting that perhaps ating plants have been reported as a bluegills living in the heated water were result of the inability of fish to acclimate 464 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 rapidly to a sudden increase or decrease individuals of all sizes, were counted in in water temperature. A number of such the immediate vicinity of the dam. A cases were documented by Edsall & majority of the dead fish were gizzard Yocum (1972). From 1973 to 1977, shad. Subsequent (2-3 days later) travel several fish kills occurred at Lake Sang- around the lake indicated that a much chris. Those fish kills were investigated to larger number of fish had died at or determine whether they were related to about the same time in other portions of operations of the power plant and to the intake arm. Dead fish were not determine if they were of sufficient observed in the discharge or control magnitude to affect the fishery adversely. arms. All fish had been dead too long to determine the cause of death, but their distribution indicated that the kill was METHODS not related to operations of the generating station. Fish kills were investigated immedi- second fish kill occurred on 4 ately upon notification. The quantity of The May 1974 in the discharge canal area (Station physical and chemical data recorded at 5, Fig. 1). were so quickly notified of the site and the number of water samples We fish kill that were able collected varied according to the that we to particular situation. The numbers of investigate while fish were still in distress. quality fishes killed were estimated by counting Water samples and water individuals washed up along portions of measurements were taken at six equidistant locations the gener- the shoreline. The estimate was presented between ating station and Station 4 (Fig. 1) and as a range, with the lower value representing the approximate number of from the slag pond overflow. During the fish kill. Unit No. 2 (Kincaid Generating fish counted. We assumed that 50 Station has two units) was percent of the fish sank and doubled the 616-megawatt generating electricity and was being approximate count to get the upper value of the range. At Commonwealth serviced by two of the four circulating capacity Edison Company's request, fishes that water pumps (605.6 m^/min each). The first appearance of distressed died during two of the fish kills and some fish observed local fishermen and control fishes captured live from the lake by by the creel clerk correlated with the were frozen and sent to Industrial was Bio-Test Laboratories, Northbrook, time when a third circulating water was activated at the generating Illinois, and to the Warf Institute, Inc., pump utility cleaned Madison, Wisconsin, for physiological station. The had recently and/or chemical analyses. the condenser of Unit No. 1 by a mechanical process, which involved shooting plastic pellets through the RESULTS AND DISCUSSION condenser tubes under high air pressure to remove silt, slime, and algal deposits. The first fish kill was reported in the According to the utility, no chemicals vicinity of the dam (Station 3, Fig. 1) on were used in the cleaning process. There 15 April 1974. Investigation revealed that was an obvious relationship between the most of the fishes had been dead for 1-5 appearance and distribution of plastic days. Water quality parameters were pellets and dead fish in the lake. Neither measured in profile form from a large external examination of the dead fish nor cove east of the dam, where many of the water quality measurements (Table 19) dead fishes had accumulated. All water taken while the fish kill was in progress quality parameters were normal at that gave any clue to its cause. From 5,000 to time; water temperature (15.5°-16.2°C), 10,000 fish were estimated to have been dissolved oxygen (9.3-10.3 mg/1), and killed, including all species normally conductivity (309-329 f.(mho/cm). Ten found in this area of the lake. The good species of fishes, including 621 physical condition of the fish indicated Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 465 9. Table 1 —Water quality measurements taken in the discharge canal and discharge arm of Lake Sangchris on 4 May 1974 while a fish kill was in progress. Relationships between locations of water sampling stations and distressed or dead fish at the time of the fish kill were; Station 1 was beyond the limit of the fish kill, since no dead or distressed fish were present; at stations 2-5 dead fish were present on the surface and others were in distress; and at Station 6 in the discharge canal (located above the point of entry of the slag pond outlet) few dead or distressed fish were present on the surface due to the swift current. Station 7 was located at the point where the slag pond outlet entered the discharge canal. Fish Kill Water Sampling Stations Parameter 1 466 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Warf Institute found massive hemor- Kincaid Generating Station. Cooling rhages behind the gills and/ or along the water from both units travels backbone in the abdominal cavity in underground through a common pipe for three of ten specimens they examined, a linear distance of more than 100 m but did not know the significance of this before entering the head of the discharge alteration. canal. Thus, fishes could have entered Although the tvi^o fish kills which the pipe within the generating station occurred in the discharge canal were and found refuge from the high water undoubtedly related to operations of the velocities by passing the junction where generating station, little conclusive water from Unit No. 2 was received. If evidence has been found to suggest the fishes reached this potential refuge area causative factor. Possible explanations (created only when Unit No. 1 was not in include the following: (1) temperature operation), they could have suffered con- shock, (2) oxygen depletion, (3) cussion when the unprimed pumps were concussion from the activation of an activated. This hypothesis was tested unprimed pump, and (4) toxic after the second discharge-canal fish kill. substances, especially chlorine. Access to the refuge area was gained The change in water temperature in through water boxes within the gener- the discharge canal when an additional ating station, and the refuge was treated circulating water pump is activated is with a fish toxicant (rotenone). No fish approximately 2.2°C. During the 1974 were recovered in the test, indicating that fish kills, gizzard shad were probably the fish probably were unable to enter the most abundant species in the canal. discharge pipe. Edsall & Yocum (1972) reported that a To prevent biological fouling of temperature decrease of 13.89°C was condenser tubes at the generating station, needed to cause 50-percent mortality of chlorine is injected several times a day by gizzard shad acclimated at 25°C. It is automatic pumps. The discharge-canal therefore unlikely that the 2.2°C fish kills did not occur when chlorine was temperature drop was lethal to gizzard scheduled to be added. However, a shad. In addition, from 1974 to 1977 in malfunctioning valve may have allowed both midsummer and midwinter, chlorine to leak into the system. If a valve changes in water temperature of much was leaking, a reservoir of chlorine could greater magnitudes were observed during have accumulated in Unit No. 1 and start-up and emergency shutdowns of would have been discharged as a con- both units at the generating station, and centrated slug when the third pump was no fish kills resulted. activated. This action could easily have During the first discharge-canal fish caused the kind of fish kill that occurred kill, biodegradable residues removed in the discharge canal. from the condenser tubes by mechanical Information regarding the physio- cleaning could have temporarily depleted logical damage to fishes caused by high oxygen reserves. However, dissolved chlorine concentrations was not found in oxygen concentrations measured while the a survey of the literature. Authors of a fish kill was occurring were all near paper on the toxicity of chlorinated saturation. Considering that (1) power plant condenser cooling waters to additional mechanical cleaning did not fish were contacted (Basch & Truchan occur prior to the second discharge-canal 1976), and they indicated (personal fish kill, and (2) the same cleaning process communication, June 1978, Michigan has been used by the utility without Department of Natural Resources) that incident since 1974, it is unlikely that the they had commonly observed bleeding of fish kills were related to residues the g^lls and hemorrhage along the spinal discharged during the mechanical clean- column and lateral line as s\Tnptoms of ing process. fishes exposed to concentrations of No screens prevent fish from entering chlorine. These symptoms were identical the 4.6-m diameter discharge pipe at to those observed in some of the fish kill Aug. 1981 TRANCiUILLI ET AL. : FISHERY POPULATION DYNAMICS 467 specimens of 4 and 28 May 1974 by the percent), channel catfish (4.7 percent), Warf Institute and Industrial Bio-Test white bass (4.6 percent), black bullhead Laboratories. On the basis of this (1.9 percent), and white crappie (1.0 evidence, we believe that the two fish kills percent). that occurred in the Lake Sangchris 2. — Lake Sangchris has not discharge canal were very likely the result experienced the decline in production of of accidental chlorination at the largemouth bass commonly observed in generating station. unheated Illinois reservoirs as they age. Standing-crop data were used to assess 3. — Gizzard shad, blackstripe the impact of the discharge-canal fish topminnow, and freshwater drum were kills on the fishery. In six standing-crop significantly more abundant in heated surveys conducted at Lake Sangchris, an than in unheated areas of the cooling average of 11 ,331 fish and a maximum of lake, while black bullheads and white 30,523 fish were found per hectare. suckers were significantly more abundant During the spring, fish were concentrated in the unheated areas. in the discharge canal, and so the 4.— Seasonal aggregations of white maximum standing crop value was used bass and channel catfish in heated areas in the analyses. This value probably was a were revealed in significant station-by- conservative estimate of the actual month interactions and related to number of fish/ ha present. The fish kill important changes in the reproductive estimates of 10,000 and 80,000 fish on 4 life histories- of these species in cooling and 28 May 1974 were thus equivalent to lakes. In the absence of major tributaries the standing crop of fish in 0.3 and 2.6 at Lake Sangchris, white bass made ha, respectively, of this 876-ha cooling pronounced upstream spawning lake. In the standing crop surveys, migrations into the discharge canal gizzard shad, an overabundant forage during early spring. In comparison with fish, constituted 73.3 percent of the total channel catfish reproduction in other number of fish collected. If gizzard shad large Illinois reservoirs, which have no comprised a similar proportion of the fish major tributaries and relatively large in the two discharge-canal fish kills, the game fish populations, channel catfish impact on the fish population would have reproduction and recruitment was been minimal. Additional evidence unusually successful in Lake Sangchris. suggesting a minimal impact on the 5. —Significant seasonal changes in fishery came from a catch-per-unit-effort relative abundance of fishes occurred fish sample collected from the discharge between heated and unheated areas of canal (Station 5) on 31 May 1974, just 3 Lake Sangchris. Gizzard shad, yellow days after the largest fish kill occurred bass, and largemouth bass were (Tables A3 and B3). No decrease in the apparently attracted to the heated areas catch (relative abundance or species during cold months and repelled from composition) was apparent, indicating them during warm months as a result of that only a small portion of the discharge behavioral thermoregulation. canal was affected by the fish kill or that 6. — Rotenone surveys revealed only the area had become quickly minor differences in standing crops of repopulated. fishes within coves between seasons or among coves located in heated and SUMMARY unheated areas of Lake Sangchris. 7.— The average standing crop of 1 . — Nine species of fishes constituted fishes in Lake Sangchris (360.9 kg/ha) 97.4 percent of the total weight of the was intermediate between those found in catch in Lake Sangchris. In order of reservoirs of the mid-South and the decreasing abundance, they were carp Midwest. (33.4 percent), gizzard shad (23.1 8. — A comparison of the standing percent), largemouth bass (16.3 percent), crop of fishes in Lake Sangchris bluegill (7.1 percent), yellow bass (5.3 determined by cove rotenone samples . 468 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 with Jenkins's (1977) regression model 15. — Body condition factors were indicated that the production of fish examined and showed that (1) through- biomass in the cooling lake was much the out the year, gizzard shad from unheated same as that in chemically similar areas were in significantly better unheated reservoirs with comparable condition than those from heated areas, total dissolved-solids concentrations. (2) bluegills from all areas of the lake were in significantly better condition in 9. — Elevated temperatures in heated than in and in areas of Lake Sangchris advanced the July November, (3) July, condition factors of bluegills were date of largemouth bass spawning by 1-3 mean higher in heated than in unheated areas, weeks over that in unheated areas and the opposite was true during consequently provided a head start in while These differences were growth for young-of-the-year fish. November. related to the relative abundance and/or 10. — In 1975, carp spawning ap- use of fish food resources in heated and parently began at the same time in both unheated areas and to greater metabolic heated and unheated areas, but in 1976 requirements of fishes inhabiting ther- carp began to spawn approximately 1 mally affected zones. month earlier in heated areas. 16.— The overall incidence of 1 1 — A degenerate ovarian condition infestation by external parasites and was found in approximately 20 percent of disease organisms in fishes from the the female carp examined and may have intake and discharge arms of the lake was partially accounted for the absence of very low at 0.6 and 0.3 percent, successful reproduction by that species in respectively. No gas-bubble disease was Lake Sangchris. Results of chemical ever observed on fishes from Lake analyses indicated that mercury and Sangchris. pesticide contamination probably did not 17. The average internal infestation cause the degenerate ovarian condition. rate for the eight species of 'fishes 12. distribu- —Length-frequency examined was 37.3 percent for the intake tions showed that the Lake Sangchris arm and 30.2 percent for the discharge carp population was composed almost arm. The incidence of internal parasitism large individuals, whereas the entirely of was greatest in bluegills, largemouth bluegills yellow bass populations of and bass, and white crappies. consisted almost entirely of small fish. 18. — Heavy parasitic infestations of 13.— The growth of carp, gizzard bluegills by the white liver grub, shad, bluegills, and yellow bass in the Posthlodiplostomum minimum, may cooling lake was slow in comparison with have contributed to the stunted condition that of these species in other waters, of the bluegill population in the cooling while the growth of white bass, large- lake. mouth bass, channel catfish, and 19. —Three fish kills occurred at Lake freshwater drum was greater than the Sangchris during 1974, and two were average growth of these fishes in other related to operations at the electrical waters. generating station. Examination of dead 14.— Weight-length relationships for fishes indicated that the two fish kills eight species of fishes in Lake Sangchris which occurred in the discharge canal were compared and found to be similar at were very likely the result of inadvertent heated and unheated stations. Significant chlorination at the power plant. differences in weight-length regressions 20. —The fish kills which occurred at were found among seasons for Lake Sangchris had a minimal impact on largemouth bass and bluegills. the fishery. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 469 REFERENCES CITED Bonn, E.W. 1953. The food and growth of young white bass (MoTone chrysops) in Lake Texoma. American Fisheries Society Transactions Adair, W.D., and Hains. 1974. Saturation J.J. 82:213-221. values of dissolved gases associated with the Box, G.E.P., and Cox. 1964. An analysis of occurrence of gas-bubble disease in fish in a D.R. transformations. Royal Statistical Society heated effluent. 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Sharitz, eds.. distribution of fishes in the New River, Glen Thermal ecology. AEC Symposium Series Lyn, Virginia. Wildlife Monographs 50. 40 p. (CONF-730505). Augusta, GA. SuLE, M.J. 1981. First-year growth and feeding of Mraz, D.. and EL. Cooper. 1957a Natural repro- largemouth bass in a heated reservoir. Pages duction and survival of carp in small ponds. 520-535 in R.W. Larimore andJ.A. Tranquilli. Journal of Wildlife Management 21(l):66-69. eds.. The Lake Sangchris study: case history of of carp, Illinois cooling lake. Illinois Natural History , and 19576. Reproduction an largemouth bass, bluegills, and black crappies Survey Bulletin 32(4). in small rearing ponds. Journal of Wildlife J.M. McNuRNEY, and DR. Halffield, Jr. Management 21(2):127-133. 1981. Food habits of some common fishes from 1974. Distribu- heated and unhealed areas of Lake Sangchris. Neill, W.H.. and J.J. Magnuson. tional ecology and behavioral thermoregulation Pages 600-519 in R.W. Larimore and J. A. of fishes in relation to heated effluent from a Tranquilli. eds.. The Lake Sangchris study: case power plant at Lake Monona, Wisconsin. history of an Illinois cooling lake. Illinois American Fisheries Society Transactions Natural History Survey Bulletin 32(4). 103(4):663-710. and J. A. Tranquilli. 1979. NiKOi-sKY, G.V. 1963. The ecology of fishes. Fecundities of fishes from Lake Sangchris and Academic Press, London and New York. 352 p. Lake Shelbyville. Pages 7-1-7-36 in Evaluation Otto. R.G. 1976. Thermal effluents, fish, and gas of a cooling lake fishery. Vol. III. Prepared by bubble disease in southwestern Lake Michigan. Illinois Natural History Survey for Electric Pages 121-129 in G.W. Esch and R.W. Power Research Institute, Palo Alto, CA. McFarlane. eds., Thermal ecology. Vol. II. SwEE. U.B., and H.R. McCrimmon. 1966. Repro- ERDA Symposium Series (CONF 750425), ductive biology of the carp, Cyprinus carpio L., Augusta, GA. in Lake St. Lawrence, Ontario. American Fish- Pflieger. W.L. 1975. The fishes of Missouri. eries Society Transactions 95(4):372-380. Missouri Department of Conservation. 343 p. Tranquilli, J. A., T. Joy, and J.M. McNurney. Rawson. M.V., and W.A. Rogers. 1972. The 1979a. A comparison of fish standing crops in seasonal abundance of the Ancyrocephalinae Lake Sangchris and Lake Shelbyville. Pages 2-1-2-7 (Monogenea) on largemouth bass in Walter F. in Evaluation of a cooling lake fishery. Natural History George Reservoir. Helminthological Society of Vol. III. Prepared by Illinois for Electric Power Research Institute. Washington Proceedings 39(2): 159-162. Survey Palo Alto. CA. RuTLEDCE, 1975. The fishes of Lake Arlington, C.J. KocHER, , R. and H. Texas — a reservoir receiving a heated effluent. Bergmann. 19796. Fish population dynamics in M.S. Thesis. University of Texas, Arlington. 71 p. Lake Sangchris and Lake Shelbyville. Pages Ryder. R.A. 1965. A method for estimating the 1-1-1-34 in Evaluation of a cooling lake fishery. the potential fish production of north- temperate Vol. III. Prepared by Illinois Natural History lakes. American Fisheries Society Transactions Survey for Electric Power Research Institute, 94(3):214-218. Palo Alto, CA. Satterthwaite, F.E. 1946. An approximate dis- J.M. McNuRNEY, and R. Kocher. 1979c. tribution of estimates of variance components. Growth, movements, and population estimates Biometrics 2(6):110-114. for fishes from Lake Sangchris determined by Shields. 1957. Experimental control of carp J.T. tagging studies. Pages 4- 1-4-35 m Evaluation of reproduction through water drawdowns in Fort a cooling lake fishery. Vol. III. Prepared by Randal Reservoir. South Dakota. American Illinois Natural History Survey for Electric Transactions Fisheries Society 87:23-33. Power Research Institute, Palo Alto, CA. Smith, P.W. 1979. The fishes of Illinois. University D.W. Dufford. R.W. Larimore, R. of Illinois Press, Urbana. 314 p. Kocher. and J.M. McNurney. 1981a Radio- Smith, S.F. 1971. Effects of a thermal effluent on telemetry observations on the behavior of aquatic life in an east Texas reservoir. largemouth bass in a heated reservoir. Pages 472 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 559-584 in R.W. Larimore and J. A. Tranquilli, vations. Waif No. 40613861387; 4110704-0705. eds.. The Lake Sangchris study: case history of Warf Institute. Inc., Madison. WI. 7 p. an Illinois cooUng lake. Illinois Natural History Webb, J.F.. and D.D. Moss. 1968. Spawning Survey Bulletin 32(4). behavior and age and growth of white bass in McNuRNEY. AND R. KoCHER. 1981fc. Center Hill Reservoir. Tennessee. Southeastern , J.M. Results of a multiple-objective fish-tagging Association of Game and Fish Commissioners program in an artificially heated reservoir. Proceedings for 1967. 22:343-357. Pages 5S6-558 in R.W. Larimore and J. A. Whitaker, J.O., and R.A. Schlleter. 1973. Tranquilli. eds., The Lake Sangchris study: case Effects of heated discharge on fish and history of an Illinois cooling lake. Illinois invertebrates of White River at Petersburg, Natural History Survey Bulletin 32(4). Indiana. Indiana University Water Resources Walker, C.R., R.E. Lennon, and B.L. Berger. Research Center. Report of Investigations 6. 1964. Preliminary observation on the toxicity of Bloomington, IN. 123 p. antimycin A to fish and other aquatic animals. Witt, A., Jr., R.S. Campbell, andJ.D. Whitley. U.S. Department of the Interior, Bureau of 1970. The evaluation of environmental Sport Fisheries and Wildlife Circular 186. 18 p. alterations by thermal loading and acid Ware iNsrrnjTE, Inc. 1974. Letter to Mr. Ed Juracek, pollution in the cooling reservoir of a steam- environmental officer. Commonwealth Edison electric station. Missouri Water Resources Company, including technical results of heavy Research Center, University of Missouri, metal analyses and gross pathological obser- Columbia. Project No. A-020-Mo. 99 p. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 473 APPENDIX A NUMBERS OF FISHES IN BIMONTHLY COLLECTIONS Table Al. —Total number of fishes collected from Lake Sangcfiris during January 1974. The sampling effort at each station consisted of 1 hour of alternating-current electrofishing, one {24-hour) experimental gill net set, and four seine hauls. Station Species 474 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table A3. —Total number of fishes taken from Lake Sangcfiris during May 1 974. The sampling ef- fort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) experimen- tal gill net set, and four seine hauls. Aug. 1981 Tran^juilli et al. : Fishery Population Dynamics 475 Table A5. —Total number of fishes taken from Lake Sangchris during September 1 974, The sampl- ing effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) ex- perimental gill net set, and four seine hauls. 476 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table A7. —Total number of fishes taken from Lake Sangchris during January 1975^ The sampling effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) experi- mental gill net set, and f( Aug. 1981 TRANqUILLI ET AL.: FISHERY POPULATION DYNAMICS 477 Table A9. —Total number of fishes collected from Lake Sangchris during [^ay 1 975. The sampling effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) experimental gill net set, and four seine hauls. 478 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table All. —Total number of fishes taken fronn Lake Sangchris during September 1975. The sampling effort at each station consisted of 1 hour of alternating-current electrofishmg. one (24-hour) experimental gil l net set, and four seine hauls. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 479 Table A13- —Total number of fishes taken from Lake Sangcfirls during January 1976, The sampl- ing effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) ex- perimental gill net set, and four seine hauls, Station Species Total Gizzard shad 185 900 1,094 Carp 29 5 44 Hornyhead chub Golden shiner Striped x golden shiner hybrid Striped shiner Bigmouth shiner Red shiner White sucker Black bullhead Yellow bullhead Channel catfish Flathead catfish Blackstripe topminnow White bass 11 3 15 29 Yellow bass 4 28 760 797 Green sunfish 27 1 8 36 Bluegill 102 107 9 219 Bluegill X green sunfish hybrid Largemouth bass 8 8 2 18 White crappie 1 1 3 Freshwater drum 1 1 Total number 19 767 365 7,707 2.261 Total species 11 11 11 14 Table A14, —Total number of fishes collected from Lake Sangchris during IVIarch 1976 The sampling effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) experimental gill net set, and four seine h< 480 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Table A15. —Total number of fishes collected from Lake Sangcfins during May 1976. Tfie sampl- ing effort at each station consisted of 1 hour of alternating-current electrofishmg, one (24-hour) ex- perimental gill net set, and four seine hauls. Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 481 Table Al 7, —Total number of fishes collected from Lake Sangchris during September 1976, The sampling effort at each station consisted of 1 hour of alternating-current electrofishing, one (24-hour) experimental gill net set, and four seine hauls. 482 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 APPENDIX B BIOMASS OF FISHES IN BIMONTHLY COLLECTIONS o . ' Aug. 1981 Tranquilli et al.: Fishery Population Dynamics 483 o — o o o o o-Tinoooooo OJ t^ »n CO 00 <£> ojin^inor* — o^ o O in CN CT> CTi o oio—'-Tino^Tj-r- o o o — — OJ r^ r^t^—iincncno'^ o o >— in rj- r- o o Tj- o o o o o in o o o o -^ in i£j ui CTi r^ .— i£i XI OJ o in ic OJ CM in rf in o en o OJ -^ OJ to lO O ^-" r~ en en in o ^£i o •— oi o ^ r^ o ^ (£1 o <.o o r^ o o o OOOOOOOO 00 O CO -— -^ OJininoir^GOGO:^ r->. c ao O oooQOcsoooTpcn tN^ Tj-i—iot~*ocnr->o CN) E en ^ o C ^ "D "o ro CO ^- ._ o o o Q) 00 in - 00 -H in en o *- en r* OJ O) CD 1= c mOJ —_ a ^ -> c E g o t ai cm "^ r- in (1) m _ 8i J= Si ;;r 0) .^ C O O CO CO O) CO o -^ — o - 0) CO — ii ra V 484 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 T- Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 485 -— 0(nCTico o o o O O O CO CO to cvj r- -n CO c E T3- nj to SZo «0) c 0) Wto _c o 6) E £ e.i s S- 0) — ^° E O o t« a> to fU g 0) ra V o ? I? CD B 486 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 0) ^ C a> o Is 0) "O W C O) ™ c ^• ._ ^ ma> "C c x: — t-> -^ ra m i5c =^ E o a; o o £i M C E ° 2 en CD £ o jz E- ^ 0) CO Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 487 ^ CO '" c g -— ^ != ^ "QJ ^ c x: _ O := C _ O SI o Ji 488 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 on CTi CO . ^ 03 O CO 03 CO 0) eI O 0) »- j= O ^CO .^o .^ 0) °-s CO _ CO P 1 § JD 9 ' CD CD CO n _ Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 489 U3 O O O O c^oooino»noo ^ Tji (X) to O —< (N O M Oininocooioco.—' >r\ on iD un o a en ni (0 - 2S •C C =] m n ^- O CD c _ ro = CO en ^ra ra c _i a> E.i II o .3^ 0) to O) ll CO t"^ 5 o ^gro >- ' 490 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 O O CO O^ •— !>. ^O O -^ ^ »?" o — -^ o O (M O Q. E =3 O) o "a CD CO ^ '•= "5 " ™oo w = 0) CD -Jc o t CO -^ E£i CO e- en CO CD -^-I O O CO -5 CO ra 9 ? 1 I a to SB Aug. 1981 Tranquilli et al.: Fishery Population Dynamics 491 wro LD CD O CO MCO _c E ° E 492 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 in Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 493 o o c o o. E ra g> ffl Z3 a 5 CO V5 0) o = ro E O X "O -c o o (1! 494 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 n Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 495 o o o ooooooinoo -^ iT) tX CTi »n o o^O'-^incoooiT)!— — CO « o ooCTir^^o-— — en in (Ti — o o o o o o 00 o r^ — Tj« CO o ,— Q. . CO — E Ki5 - 3 CD ra 1^ ^ c o 0) ^g03 .- CD — E "D 1- c 3 CD "O . CO = W 131 V CO «•£ —I 0) E E o c CD CD O -C j;oE=1 O , CO CJ CO g o> o o . en ic CD .W CO o CO CD E CD g t _ o Si. CD m CO 1° 496 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 T— I ' i Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 497 o o o o o o o o o to in o o "-^ QO O — iD ^ iD — C^J -^ OO 00 o^ ^- c^ (jg ^- oo in t£> — o — 00 CM XI OO on 00 00 ^N D ^- O^ iD 00 o in oi o^ r^ (£} CM (£) Os o o o o <£> o 00 ^ - r* in (M -^ »r\ O O o o o o O O O C) in to o .— — 00 in o d — ra CO a> CD ^ ^ c ^ 0) i| C 0) Mra _c ^ oH E g 2.E ^0) Q.X O dj 0) ,.^ o 5 o o ra m ^ 498 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 c Q E O) Aug. 1981 Tranquilli et al. : Fishery Population Dynamics 499 ooooinoooo r^ oo in w in o Oooinr^^-CTir^ino^ •— o o^ OCNtNUDfOTinC o»n<.oo^-or*o^ — o o o in VO 00 — CTJ 0) cO) Q. E -I CO CO ^ c J3 CO il = n 00 •— o F— O O ll re E b O Q.X i: (1) T3 -C E § re . o £ = JZ it w E o o —!q cC31 to -^ I 2 CO nj 5 o C/5 X Food Habits of Some Common Fishes from IHeated and Unhealed Areas of Lalce Sangchris Michael J. Sule, John M. McNurney, and Donald R. Halffleld, Jr. ABSTRACT complex and difficult to quantify. In ad- dition to deterrrining these relationships, largemouth bass, The food habits of researchers studying an artificially heated yellow bass, and bluegill, channel catfish, lake need to identify any deviations from were studied during freshwater drum normal fish feeding which are at- through 1976 various periods from 1974 tributable to the various water foods used and to determine the typical temperatures of the lake. This study was in feeding in a power plant seasonal shifts initiated to determine the typical foods Diets changed with season cooling lake. for fish of different lengths (ages) during they generally followed and fish size, but different seasons and to ascertain any of change in the two similar patterns changes in food habits as a result of areas and depended thermally dissimilar power plant operation. Of primary in- food resource availability. primarily on terest were the food habits of fish in- part of their growth Through some habiting the intake and discharge arms of used aquatic insects history each species Lake Sangchris and their diet changes as food. Largemouth and zooplankton relative to water temperatures. Diets of channel catfish were best bass and all major fish species of Lake Sangchris resource structure of the adapted to the except carp were examined. Results of morphological or lake because of stomach analyses are presented for features that allowed them physiological largemouth bass, Micropterus salmoides underutilized food resources. to consume (Lacepede); channel catfish, Ictalurus were No peculiar feeding relationships punctatus (Rafinesque); freshwater of Lake found among the fishes drum, Aplodinotus grunniens Rafines- rates relative to food Sangchris. Ingestion que; yellow bass, Morone mississippiensis rates were not resource production Jordan & Eigenmann; and bluegill, measured. Lepomis macrochirus Rafinesque. was the primary INTRODUCTION Largemouth bass game fish for most anglers at Lake Knowledge of the types and quantities Sangchris during the study period of food consumed by a species is necessary (McNurney & Dreier 1981). Although its for a basic understanding of the interac- popularity as a game fish was adequate tions within most ecosystems. In an qualification for food-habits investiga- aquatic ecosystem, the interrelationships tions, other characteristics of this species of various key consumers within the food in Lake Sangchris necessitated its inclu- web are usually of great interest to lake sion in any comprehensive study of the managers and fishermen but are often lake. Largemouth bass in Lake Sangchris have exhibited exceptional growth and Michael Sule is with the Illinois Department of J. good population levels longer than in Conservation, Oregon, Illinois; John M. McNurney most newly constructed reservoirs (Tran- and Donald R. Halffield, Jr.. are with R.W. Beck basic infor- and Company. Denver, Colorado. quilli et al. 1981). Therefore, needed concerning the food This chapter submitted in Sept. 1979. mation was 500 Aug. 1981 SuLE ET AL. : Food Habits of Fishes 501 resources used in such favorable bass pro- mounted regarding the potential prob- duction. Even more important was the in- lems and possible promise associated fluence this species has upon the entire with this species, and it was included lake ecosystem. Largemouth bass are among species to be examined for diet. typically piscivorous and could play a ma- Freshwater drum represented an expand- jor role in the population dynamics of the ing fish population that had the poten- various forage fishes in the system. Con- tial to provide an important future sport sidering this role of the largemouth bass fishery to the area. We also thought that and our increasing demand for electrical the free-floating eggs of the drum might energy production, knowledge gained be highly vulnerable to mechanically in- about the relationships between duced mortality from power plant en- largemouth bass and heated water can trainment. Freshwater drum might also only better equip us to meet our future act as a natural control for populations of energy and recreational needs more wise- the Asiatic clam, Corbicula fluminea, that can foul power plant condenser The food habits of channel catfish in tubes. Consequently, diets of freshwater the intake and discharge arms of Lake drum were monitored during the Sangchris were of particular interest to establishment of the species to under- biologists studying the lake because of the stand better its relationships in a heated unusual reproductive success channel cat- reservoir and to provide basic informa- fish achieved in Lake Sangchris, a lake tion for management. not expected to be conducive to channel Since the yellow bass was one of the catfish production (Tranquilli et al. six most abundant fish (by weight) in 1981). Only by knowing food habits and Lake Sangchris, it was included in the other life history information can one food-habits investigations. The yellow isolate the factors responsible for such bass population in Lake Sangchris was unexpected reproduction. The channel stunted, with only a few individuals catfish was also a prime game fish for larger than 200 mm (Tranquilli et al. Lake Sangchris anglers (McNurney & 1981). A possible cause for a stunted Dreier 1981). This reason alone has population is an inadequate food base, justifiably dictated most of the past and we studied the food habits of yellow fisheries research regarding fish food bass to determine their food source and habits. Additionally, channel catfish its adequacy. could potentially suppress growth or Bluegills were also commonly col- reproduction of other fishes in Lake lected in Lake Sangchris but were not an Sangchris through competition for important species in the creel (McNurney limited foods. For example, channel cat- & Dreier 1981). Bluegills can be an im- fish competition with bluegill and redear portant sport fish for anglers in some sunfish apparently reduced sunfish lakes; however, in Lake Sangchris they growth, condition, and reproduction and were stunted (Tranquilli et al. 1981). consequently limited bass growth in Consequently, bluegill diets were examin- Alabama farm ponds (Brown 1965). ed for comparison with those of bluegills Competition of this type as well as direct in other areas and to determine if any predation could be extremely important deviations observed were power-plant in the dynamics of a cooling lake fishery. induced. Fourthly, since channel catfish are often opportunistic omnivores (Bailey & Har- rison 1948), their diet may indicate the DESCRIPTION OF THE general condition of the fish food base of STUDY AREA the lake. Freshwater drum were not known to Lake Sangchris is an 876-ha power occur in Lake Sangchris until they were plant cooling lake situated in central Il- collected in substantial numbers during linois approximately 24 km southeast of March 1974. At that time, concern Springfield. The lake, described in detail 502 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 by Larimore & Tranquilli (1981), consists small fish were preserved in 10-percent of three arms, two of which form a cool- formalin for later examination. Stomachs ing loop for the Commonwealth Edison were individually opened, and their con- Kincaid Generating Station. The middle tents were identified to the lowest possible arm of the lake (discharge arm) receives taxon under a dissecting microscope. The cooling water with waste heat from the proportion of the meal represented by power plant and usually has temperatures each food item was determined by weight 7 °-9 ° C higher than water temperatures in (wet blotted) and recorded as a percent- the west (intake) arm. Water travels age of the total weight of food and matter per around the cooling loop and dissipates stomach. The average of these percent- waste heat before being reused by the ages was used to indicate the portion of power plant. Study sites selected for com- the diet represented by each kind of food. parison of fish food habits in the lake's Only stomachs that contained two temperature regimes (intake and measurable (< 0.1 mg) amounts of food discharge arms) were the same described were used in calculating average weight by Tranquilli et al. (1981) for fish percentages. Analyses of this type give population comparisons. equal importance to stomach contents from small and large fish and to stomachs METHODS in different stages of digestion or degrees of fullness, as discussed by Larimore During 1974 fish collections were (1957). made bimonthly in the intake (stations 1 and 2) and discharge (stations 4 and 5) arms of Lake Sangchris for each of the RESULTS AND DISCUSSION five previously mentioned species. In LARGEMOUTH BASS 1975 collections were made at approx- collected for imately 3-week intervals during the Largemouth bass stomach analysis in the intake and spring at stations 1 .5 (intake arm) and 4.5 discharge arms of Lake Sangchris totaled (discharge arm) in addition to those 792 specimens (54-754 mm total length). taken during the regular bimonthly fish Fish collected in the discharge arm of the collections continued from the previous lake constituted 57 percent of the total year. Samples from outside the cooling and were collected in equal proportion loop were not included because of limita- during 1974 and 1975. Fifty-eight per- tions of manpower and time. No channel cent of the bass from the intake arm were catfish were collected for stomach collected during 1974. Most bass were analysis in 1975. Channel catfish and captured during March, Mav. and freshwater drum are the only fish discuss- September, the 3 months in which collec- ed in this study that were collected for tions from the 2 years coincided. Over the stomach analysis during 1976. During 2-year period, bass were captured for 1976 fish were collected at approximately stomach analysis during all calendar 3- week intervals (May-October 1976) months except June, August, October, from the intake (stations 1, 1.5, and 2) and December. Although during both and discharge (stations 4, 4.5, and 5) years bass from the discharge arm averag- arms of the lake. ed greater total lengths than those from All fish analyzed for stomach contents the intake arm, mean lengths were not were collected by electrofishing along the significantly different (5-percent level), shoreline with a boat-mounted shocker, and bass collectively averaged 253 mm in which employed a 230-volt, three-phase total length. AC generator as the power source. Col- The predominant food item of bass in lections were made at night during 1974 both arms of the lake during 1974 and and during daylight hours in subsequent 1975 was fish, chiefiy gizzard shad, years. Dorosoma cepedianum (Lesueur). Fish The stomachs of large fish and whole constituted 6 L percent and 44 percent of Aug. 1981 SuLEETAL.: Food Habits OF Fishes 503 the diet of bass in the intake arm in 1974 Probably the most important in- and 1975, respectively, and averaged 54 fluence to keep in mind when comparing percent for that area overall. The diet of fish diets from different areas is the sizes iiass in the discharge arm consisted of 80 of fish that are being compared. Bass percent and 65 percent fish in those years diets in Lake Sangchris changed accord and averaged 72 percent. ing to the lengths of the fish examined. Zooplankton was more important as a Insects Vi'ere the only other food that food source to small (60 100 mm) bass contributed substantially to bass diets. than to larger ones in both study areas of Insects constituted a larger proportion of the lake (Fig. 1). Although zooplankton the food of bass from the intake arm of was never the major food of these bass, it the lake than they constituted of food of formed a substantial portion of their diet bass from the discharge arm. Collective- and showed a marked decrease in impor- ly, insects provided averages of 18 percent tance in larger fish. The fact that and 32 percent of the food that bass con- zooplankton never represented the major sumed in the intake arm during 1974 and food for Lake Sangchris bass reflected the 1975, respectively, and averaged 24 per- rather large size of the smallest bass ex- cent of the diet for all bass from the in- amined. take arm. Insects provided only 8 percent of the bass diet in the discharge arm. Bass smaller than 140 mm from both Chironomids, ephemeropterans, arms of the lake preyed primarily on in- zygopterans, and terrestrial or aerial in- sects. Insects were still consumed by bass sects were the major components of the 140-250 mm long but in greatly reduced insect portion of the bass diet. proportions. In general, bass from the in- take arm ate more insects than did those Many specimens were needed to from the discharge arm (Fig. 1). Com- evaluate the effects of heated water on paratively lower benthic biomass in the the food habits of largemouth bass. Fac- discharge channel (Webb 1981 ) was prob- tors such as time of collection and ably responsible for the difference in in- specimen size are two important variables sect consumption observed. which limit conclusions drawn from small samples collected over several years. Beyond 140 mm, bass ate virtually Another complicating factor is the nothing but fish. Bass between 80 and number of empty stomachs encountered 140 mm consumed some fish but were when examining largemouth bass. Bass still mainly insectivorous. Among bass in stomachs from the intake arm were emp- the transition stage between insectivorous ty 31 percent of the time (33 percent in size and piscivorous size, those in the 1974, 27 percent in 1975), while 38 per- discharge arm typically ate more fish cent of those from the discharge arm were than those in the intake arm. Fish con- empty (41 percent in 1974, 35 percent in sumption by largemouth bass larger than 1975). These figures are smaller than the 140 mm was nearly identical in the two average of 56 percent reported by arms of Lake Sangchris (Fig 1). Zweiacker & Summerfelt (1974) in Cyprinidae and Lepomis species were im- Oklahoma and indicate that good bass portant to small piscivorous bass, while feeding conditions generally prevailed in larger bass primarily ate gizzard shad Lake Sangchris. and secondarily ate Lepomis species. Although average percentages of cer- These results were not unlike those tain foods over entire years are adequate obtained by Sule (1981) for food habits of for an overview of a fish's diet, the effects youngof-the-year bass in Lake Sangchris upon the diet of fish size and season of during 1975. It was learned in that study collection are matters which need detail- that most zooplankton was consumed by ed examination before any evaluation largemouth bass shorter than 50 mm and can be made regarding the effects of an in lesser amounts by bass beyond that extraneous influence, such as heated size. Insect consumption, in that study, water. was also associated with bass of the size I 504 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 loo- FISH AND CRAYFISH se- = INTAKE 60- = DISCHARGE 1)0- 20- Jni JIL IJ 100- 80- LU g 60- LU § 20- 1 I u 100- ZOOPLANKTON 50- 40- 20- iL 6 15 20 N- INTAKE 5 8 15 32 31 34 N-DISCHARGE 1 1 1 1 1 1 1 1 — F— r-//-| rV/n 1 1 r 50 60 70 80 90 100 110 120 130 WO 150 200 250 300 400 500 500 700 800 FISH TOTAL LENGTH (mm) Fig. 1 . —Average weight percentages of major foods found in largemoutfi bass of different lengtfis from the intake and discharge arms of Lake Sangchris during 1974 and 1975. found here to be mainly insectivorous. fish of that size to the largest bass examin- Young-of-the-year bass were reported not ed, reliance upon fish as forage was to have preyed upon fish consistently un- equally great in both the intake and til they reached a total length of 90-100 discharge arms of the lake. These trends mm. The data presented here indicated were evident during both 1974 and 1975. that for largemouth bass in Lake For the best analysis of feeding Sangchris the complete shift from insec- seasonality, it is essential that com- tivore to piscivore may occur at around parisons of similar-sized fish be made at 140 mm. frequent intervals throughout the year. According to size, bass from both As in most analyses, the effort required arms of Lake Sangchris showed about the for such comparisons proved too great, same food habits. Those in the intake and conclusions had to be based upon arm ate more insects and less fish than smaller samples. In general, though, con- those in the discharge arm until the com- sumption of fish by bass in both arms of plete shift in food habits occurred. From the lake was high during each collection. Aug. 1981 SuLEETAL.: Food Habits OF Fishes 505 Crayfish consumption occurred mainly Carlander (1977). Although food con- during the spring. Occurrence of other sumption rates were not compared, foods, such as zooplankton or insects, was analyses of stomachs of largemouth bass primarily correlated to the size of fish ex- from the intake and discharge arms of amined. Lake Sangchris indicated that the types of foods that the diet, and the The food habits of largemouth bass made up have been extensively investigated relative proportions that each type con- tributed, were basically similar for the (Carlander 1977). Although contingent two thermally different areas. Minor dif- upon prey available in each particular ferences existed, but identical shifts in body of water, young bass generally begin feeding that accompanied changes in fish to feed upon zooplankton and as size in- length in the two lake arms suggested that creases, progressively depend more upon little disruption of the normal feeding larger arthropods (mainly aquatic in- chronology occurred. Fish predation by sects). As bass grow, their diets eventually adult bass continued throughout the shift to include larger organisms, such as seasons and by all sizes of bass examined, fish and crayfish. Bass ordinarily con- indicating that excellent forage condi- tinue to feed upon the most efficient tions existed for bass in Lake Sangchris. foods available, which generally means forage, coupled with the artificially the largest fish that bass can easily catch Good prolonged growing season, has probably and swallow. Opportunities undoubtedly led to the excellent growth of largemouth arise, however, when the abundance of bass observed at Lake Sangchris. undersized prey compensate for the inef- ficiency involved in their capture. Conse- quently, there are times when many small CHANNEL CATFISH fish or numerous terrestrial insects, for total of 399 channel catfish (79-643 example, become conspicuous in the diet A from Lake Sangchris were examined of large bass that generally prey on larger mm) for stomach contents. Seventy-five per- foods. There is also the possibility that in of the fish examined were collected some circumstances prey of the proper cent during 1974 and the rest in 1976. size are simply unavailable. What ap- Samples were evenly divided between the pears important for good bass growth and two sampling areas (intake and reproduction is adequate food of the prop- discharge) of the lake during the entire er quality (size) obtainable when it is re- study. February and December were the quired by the bass. only months not represented by samples, Sule a normal shift of (1981) found but most channel catfish were captured foods zooplankton to aquatic bass from for stomach analysis during March, May, insects and then to forage fish for young- July, and September. Average lengths of in both arms of-theyear largemouth bass channel catfish from the intake (262 mm) Feeding of Lake Sangchris during 1975. and discharge (268 mm) arms of the lake not habits of older bass, however, were during 1976 were significantly (5-percent part of that study. Our study examined as level) greater than those from their the shift in bass diets from also revealed respective areas in 1974 (intake 177 mm, zooplankton to insects and then to fish discharge 230 mm). During 1974 average and crayfish as bass increase in size. Ad- lengths of catfish from the two arms were it prey did ditionally, indicated that bass significantly (5-percent level) different. not grow so rapidly because of the The frequency of empty stomachs was 7.5 temperatures that they became elevated percent in the intake arm and 13.6 per- or unavailable to adult bass, undesirable cent in the discharge arm. and thus an adequate prey resource for Predominant food items for catfish adult bass was sustained. included insects, plants, and fish. During Overall trends in bass feeding were 1974 the diets of channel catfish in both similar in both arms of Lake Sangchris arms of Lake Sangchris were dominated and also were similar to those reported by by insects. Stomach contents averaged 47 506 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 percent insects for catfish from the intake variations in the diets of catfish from dif- arm and 34 percent for those from the ferent areas are largely dependent upon discharge arm. In both cases, food availability. Bailey & Harrison chironomids represented over 90 percent (1948) attributed the small quantity of of the insect biomass consumed. Fish filamentous algae, microcrustaceans. matter and plant matter each con- crayfish, and moUusks in catfish stomachs tributed approximately 9 percent to the to the low abundance of these foods in the diet of catfish in the intake arm during Des Moines River. But they also found 1974. These latter foods constituted 12 that channel catfish were omnivorous; percent and 18 percent, respectively, of the young fed almost exclusively on the catfish diet in the discharge arm. aquatic insect larvae, and larger catfish Catfish captured during 1976, progressively used larger insects and elm however, fed mainly on plants. Plant seeds. matter, consisting mostly of filamentous The differences between channel cat- algae, averaged 68 percent of the diet of fish diets in the two arms of Lake catfish in the intake arm and 49 percent Sangchris were trivial compared to the in the discharge arm. Insects were less im- observed differences between years and to portant to catfish than during 1974 and the results offered by various in- averaged 19 and 7 percent of the diet in vestigators. Observed differences, the intake and discharge arms, respec- however, may have resulted from a factor tively. The 2.7-fold difference in insect commonly overlooked. Diets of channel consumption between the two arms dur- catfish changed in Lake Sangchris accord- ing 1976 was mainly due to increased ing to size of the fish examined, and fish consumption of Hexagenia mayflies in examined during the 2 separate years the intake arm. Swadener & Buckler were of different sizes. (1979) found that the intake arm of Lake Channel catfish between 100 and 200 Sangchris typically had greater Hex- mm total length fed heavily on insects agenia populations than did the dis- (Fig. 2), especially chironomids. As cat- charge arm. Fish collections may also fish lengths exceeded 200 mm, the por- have inadvertently corresponded to tion of the diet that consisted of insects periods of emergence of these burrowing decreased until no insects were consumed invertebrates, times when they would by catfish larger than 400 mm. Plant have been readily available and matter, mostly filamentous algae, was vulnerable as prey. Crayfish were a eaten by channel catfish as small as 135 relatively unimportant food resource for mm but became most prominent in fish channel catfish overall, but during 1976 between 200 and 500 mm. Fish and represented a greater portion of the cat- crayfish did not form a consistent part of fish diet than did fish. the diet until channel catfish exceeded a Shira (1917). Boesel (1938), Hoopes total length of 260 mm. (1960), and Ware (1967) all found that The shift in food from insects to insect larvae, mostly Chironomidae and plants and then to fish or crayfish, as Ephemeroptera, were most important to channel catfish increased in size, was evi- channel catfish and that plant matter was dent in both the intake and discharge used little as a food resource. However, arms of Lake Sangchris. This trend was Dill (1944) found that aquatic and higher exhibited best by fish captured during plants were of chief importance to chan- 1974 because fish sizes during that year nel catfish in the Colorado River. McCor- ranged from 79 mm to 492 mm. During mick (1940) also found that filamentous 1976 the catfish examined were generally algae were important to channel catfish larger, and none shorter than 178 mm from Reelfoot Lake, and Menzel (1943) were analyzed. Specimens collected dur- found that channel catfish from a river in ing 1976 indicated diets similar to those Virginia fed primarily on filamentous of channel catfish of equal size captured algae during August. The omnivorous in 1974. habits of the channel catfish indicate that Analyses of seasonal feeding indicated Aug. 1981 SuLEETAL.: Food Habits OF Fishes 507 80- 508 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 2 1/4 -year study period, samples were very important as food of freshwater taken from the discharge arm in every drum in both arms. However, substantial month except August from March increases occurred in the consumption of through November and in the intake arm MoUusca, especially in the discharge arm from May through November, except in (26 percent), and of Ephemeroptera in October. the intake arm (66 percent). The Fig. 3 shows relative quantities of Ephemeroptera consisted almost entirely selected food items eaten by freshwater of a Hexagenia species, large burrowing drum in the intake and discharge arms in mayflies, while the MoUusca were 1974, 1975, and 1976. Chironomids were primarily Corbicula fluminea. The mean the most important food item at all times length of freshwater drum sampled was except in the intake arin in 1976 and in 35 percent greater in 1976 than in 1974, the summer of 1974, when and thus, the diet change observed in Ephemeroptera (primarily Hexagenia 1976 reflected the increase in the size of spp.) were the predominant food item. freshwater drum, Corbicula populations Overall, the percentages of empty were denser in the discharge arm (Dreier stomachs were 8.9 from the discharge & Tranquilli 1981), possibly explaining arm and 3.3 from the intake arm. The the higher comsumption of Corbicula percentage of empty stomachs was con- there. Ephemeropteran populations were sistently higher in the discharge arm in all substantially higher in the intake arm 3 years of the study; however, empty than they were in the discharge arm dur- stomachs always represented less than 10 ing the summer of 1976 (Swadener & percent of the total. Buckler 1979). Since a majority of the Freshwater drum displayed similar freshwater drum examined were collected food habits in the intake and discharge in the summer in 1976, the high con- arms during 1974 and 1975, when sumption of ephemeropterans in the in- Chironomidae predominated over all take arm by freshwater drum was a other food items, each of which averaged reflection of ephemeropteran abundance less than 10 percent of the weight of all during a period when freshwater drum food. In 1976 Chironomidae were still were intensively collected. 1971 Aug. 1981 SuLEETAL.: Food Habits OF Fishes 509 100- = INTAKE 80- = DISCHARGE 60- MOLLUSCA to- 20- , -^ J J J if^l S 100- t~ EPHEMEROPTERA § 80- Q= LU Q- ,- 60- LU S 20- .^JiL 1 CHIRONOMIDAE la 23 253344565684 11 17 11 10 7 5 11 6 9 2 2 2 ] N-DISCHARGE 100 120 »° 15° 1^° 2"» 2^° '•*° ^6" 2^° ^^^ '^^ ilo 130 150 170 190 2I0 230 250 270 MO 3^0 380 FISH TOTAL LENGTH (hh) Fig. 4. —Average weight percentages of major foods found in freshwater drum of different lengths from the intake and discharge arms of Lake Sangchris, 1 974-1 976, Freshwater drum were divided into in connection with any of the major food lO-mm size groups to study food-habit items. The food habits of freshwater drum trends relative to changes in fish size (Fig. in Lake Sangchris were similar to those 4). The main shift observed was that of reported in the literature. High consump- increasing consumption of Mollusca and tion of invertebrates, such as Ephemeroptera and a decrease in the use Chironomidae and Ephemeroptera, and of Chironomidae as freshwater drum sizes low consumption of fish and Mollusca increased. Feeding on Corbicula by were reportedly typical for small freshwater drum was of particular impor- freshwater drum in a lake ecosystem tance in Lake Sangchris, since Corbicula (Scott & Grossman 1973). A shift to larger had been identified as a nuisance species food items, such as fish, crayfish, and in the lake because of its habit of coloniz- Mollusca, as drum increased in length ing the condenser tubes of the power has been reported by several authors plant. Increased consumption of Cor- (Daiber 1952, Dendy 1946, Forbes 1888, bicula would be expected as the relatively and Moen 1955). young population of freshwater drum in Lake Sangchris matures and more YELLOW BASS specimens reach larger sizes. A total of 691 yellow bass was col- To determine seasonal trends, food lected in Lake Sangchris for stomach habits were examined by month by analysis during 1974 and 1975. Of these, combining all sizes of freshwater drum; 56 percent were from the discharge arm however, no feeding trends were observed with the remainder from the intake arm. 510 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Yellow bass ranged in size from 67 to 247 in 1975 zooplankton heavily mm with 96 percent being between 80 predominated in the diet of yellow bass and 180 mm. The mean total length was from the discharge arm. The reason for 130 mm in the intake arm and 122 mm in this predominance was unclear. In the the discharge arm. Yellow bass were col- discharge arm zooplankton was consum- lected in March, April, May, July, ed during all months to a greater degree September, and November in both arms than in the intake arm and by all sizes of and additionally in January and February yellow bass except the 90-100 mm group. in the discharge arm. Therefore, sampling bias due to fish size Zooplankton and Chironomidae were or seasonality was not indicated. Zoo- the predominant food items of yellow plankton populations were similar in both bass in both arms of Lake Sangchris areas of the lake during this period (Brig- in both years. Chaoboridae, Ephemerop- ham et al. 1975). Chironomidae populations tera, and plant material were also eaten were known to be low in the discharge but were minor food items relative to canal (Webb 1981): however, even if fish zooplankton and Chironomidae. During collected from the discharge canal were 1974 these food items were eaten in excluded from the sample, zooplankton similar amounts in both arms; however, predominated among the food items 30-1 n= INTAKE 20- M= DISCHARGE 10 30' EPHEMEROPTERA 20 10 1 30 CHAOBORIDAE 20 10- ^ n_. ^n. 10 30 20 10 n n ^li^ Fig. 5. —Average weight S 80 percentages of major foods CHIRONOMIDAE found in yellow bass of dif- I 60- ferent lengths from the intake and discharge arms of Lake Sangchris during 1974 and 1975 ^ 20- a: ILik 1[I LUltJLj. 90 ZOOPLANKTON 80- 60- 40- 20- 1 -1 1 1 1 1 1 r 60 70 80 90 100 110 120 130 ItO 150 160 170 180 200 FISH TOTAL LENGTH (mm) Aug. 1981 SuLE ET AL. : Food Habits of Fishes 511 eaten by yellow bass in the rest of the Chaoboridae, Ephemeroptera, and fish discharge arm. Yellow bass were of increased with increasing yellow bass size. similar mean sizes in both arms in 1975, This shift to larger prey items at the 134 mm and 129 mm for the intake and larger fish sizes, which was similar to that discharge arms, respectively. The propor- found for stunted populations of yellow tions of empty stomachs were 6.6 percent bass in Iowa (Kutkuhn 1954, Collier in the intake arm and 4.9 percent in the 1959, Ridenhour 1960, Kraus 1963, and discharge arm. Welker 1963), occurred in both arms but Yellow bass were divided into 10-mm was most pronounced in the intake arm. size groups in order to examine shifts in In the discharge arm, although yellow feeding associated with fish size (Fig. 5). bass consumption of zooplankton declin- Zooplankton consumption declined with ed as yellow bass grew, zooplankton still increasing size, while consumption of dominated the food base of even large = INTAKE 20H = DISCHARGE XL EPHEMEROPTERA 20- J] ^ Jl H _a. CHAOBORIDAE 20- lOOn CHIRONOMIDAE Fig. 6- —Average weight percentages of major foods found in yellow bass from tfie intake and discfiarge arms of Lake Sangcfiris during dif- ferent months of 1974 and 1975 LJJ H ZOOPLANKTON LiJ 5 11 104 25 N-INTAKE 62 53 46 24 68 17 N-DISCHARGE NOV JAN FEB MAR APR MAY JUNE JUL AUG SEPT OCT 512 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 size classes. Chironomidae, plant tions began feeding on fish earlier material, Ephemeroptera , and (130-150 mm) than did stunted popula- Chaoboridae were eaten by most sizes of tions, where almost no fish were eaten by yellow bass to a greater degree in the in- yellow bass of less than 200 mm in total take arm than in the discharge arm. length. These general trends were observed in The stunted population of yellow bass both years of the study. in Lake Sangchris appeared to be forced to eat primarily zooplankton Weighted monthly averages of through an extensive samples taken over the 2-year study portion of their growth history. Since zooplankters were abandoned as period were compiled to determine possi- forage early in the growth histories of ble seasonal trends of yellow bass feeding other fish species, zooplankton (Fig. 6). Consumption of zooplankton represented an acceptable forage item was greatest in winter, early spring, and that was under less competitive pressure late autumn and least in midsummer and than were the large aquatic insects. This early autumn in both arms. Yellow bass niche segregation subsequently suppress- consumption of Chironomidae in the ed further growth of yellow bass, since discharge arm followed a reverse trend to zooplankton represent an inefficient that of zooplankton consumption in that source of nutrition for large yellow bass it was high in midsummer and early and thus limit their choice of alternate autumn and low at other times of the foods by limiting yellow bass growth. year. Consumption of chironomids in the intake arm was less in the summer and greater in the spring and autumn. BLUEGILL were the dominant food of Chaoboridae Approximately half of the 1.341 yellow bass in the intake arm in midsum- bluegills examined during the food- mer, when their use of Chironomidae and habits study were collected during each of zooplankton was low. While these same the 2 study years, 1974 and 1975. Begin- trends were identified during 1974, insuf- ning in January of 1974, approximately ficient data made seasonal trends during 100 fish were captured during each of 1975 difficult to discern. Thus, in the twelve 2-month periods. Half of each discharge arm yellow bass shifted their bimonthly collection came from the feeding from zooplankton to heated (discharge) arm of the lake, while Chironomidae in the and early summer the other half came from the intake arm. fall, while in the intake arm the shift was Size distributions of the collected bluegill from zooplankton and plant material in were very similar in the heated and the winter in spring to to Chironomidae unhealed arms although some small Chaoboridae and Ephemeroptera in sum- seasonal variations in length frequency to mer and zooplankton and distributions were apparent. Chironomidae in fall. The food habits of bluegills in Lake Virtually all previous investigations of Sangchris during 1974 and 1975 were in- yellow bass food habits have been done in fluenced by competition for food, the summer in North Twin Lake and availability of food resources, and Clear Lake, Iowa (Collier 1959, Kraus temperature. The effects of both in- 1963, Kutkuhn 1954, Ridenhour 1960, traspecific and interspecific food com- petition bluegills in and Welker 1963). In these lakes it was were evident among found that young- of- the- year yellow bass the discharge and intake arms. The ef- fed heavily on zooplankton and dipteran fects of the power plant in the discharge larvae with increasing ingestion of arm influenced bluegill food habits in- dipteran larvae as the fish grew larger. directly by reducing benthic biomass in Other aquatic insects became more im- the discharge channel and directly by ap- portant as fish increased in size until parently increasing their feeding rate. forage fish predominated in the diet of Food items used by bluegills in Lake large yellow bass. Nonstunted popula- Sangchris were generally similar to the Aug. 1981 SuLE ET AL. : Food Habits of Fishes 513 loo- se- 60- = INTAKE » DISCHARGE lO- 20- .iMi W- 20- — r-^ - r-— r-« to- TERRESTRIAL INSECTS 20- rL r^ rafb m Fig 7 — Average weight percentages of major foods 100 -I found in bluegill of different lengths from the intal to- 20- ^^B^Ur. 100- ZOOPLANKTON 80- 60- 40- 20- 30-39 140-49 |50-59 160-69 |70-79|80-89 190-99 llOO- |l20- |l40- |l60- |180- I I I I I I I 119 I 139 I I59I 179I 1 FISH TOTAL LENGTH (mm) items reported for other bluegill popula- September and October (Fig. 8). In con- tions. Aquatic insects, mainly trast, this was a period of low use of Chironomidae, were an important food aquatic insects by bluegills in two item for bluegills of all sizes (Fig. 7), as Wisconsin lakes (Seaburg & Moyle 1964) reported by other researchers (Gerking and in Lake Opinicon, Ontario (Keast 1962, Keast & Webb 1966, and Seaburg 1978). Zooplankton consumption by & Moyle 1964). Peak use of aquatic in- bluegills in Lake Sangchris was similar to sects at Lake Sangchris occurred in that reported for other waters. 514 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 50-1 PLANTS ~L = INTAKE iJO- I ^^ = DISCHARGE 20H J II I i ^ B TERRESTRIAL INSECTS 20' a. n i^ rl r^ -_ 100-1 80- AQUATIC INSECTS 60- Fig. 8. —Average weight percentages of major foods found in bluegill from the in- 40 take and discharge arms of CJ3 Lake Sangchris during dif- ferent seasons of 1974 and 20-1 1975- D^ ^ rk ^ lU 100- 80- ZOOPLANKTON 60 40- 20- JL^ 1 m L81 94 152 98 95 86 N- INTAKE 94 141 147 108 103 99 N-DISCHARGE JAN/FEB MAR/APR MAY/JUNE JUL/AUG SEPT/OCT NOV/DEC Zooplankton formed a major portion of Sangchris. These were reported as the diet of all blueg^lls during the winter variably important food items by Keast & (Fig. 8), as also reported by Goodson Webb (1966) and Gerking (1962). (1965) and Moffett & Hunt (1943), and it Seasonal transitions were apparent in was consistently eaten by small bluegills the diets of bluegills from both the in all seasons (Fig. 7), as reported by discharge and intake arms of Lake Keast (1978). Aquatic plants and ter- Sangchris (Fig. 8). The cycles in both restrial insects were also major com- areas were similar. As had been the case ponents of the diets of bluegills in Lake for yellow bass, the most important food Aug. 1981 SuLE ET AL. : Food Habits of Fishes 515 item for bluegills in the winter months October period. Since bluegills smaller was zooplankton. Aquatic plant use peak- than 120 mm predominated the samples ed in the spring and then declined as as well as in the population, their food more aquatic and terrestrial insects were habits considerably influenced any consumed until a peak in aquatic insect population-wide study. Seasonal trends consumption occurred in the September- for large, 140-159 mm, bluegill (Fig. 9) 100- PLANTS = INTAKE 80- ^ DISCHARGE 60- 40 20-1 Fig. 9. —Average weight percentages of major foods found in large bluegill (140-159 mm) from the intake and discharge arms of Lake Sangchris during different seasons of 1974 and i975. 516 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 were compared with those of smaller fish able to feed on selected food items of 100-119 mm (Fig. 10). While seasonal throughout the year. Smaller bluegills trends typical of the total population were probably forced, by competition were found for the small fish, only minor with larger bluegills and other species, to seasonal variations were noted in the diet use whatever food resources were of the larger bluegills. The larger fish, available. with a competitive size advantage, were The food items consumed by bluegills = INTAKE 60-1 B"°'5CHARGE PLANTS 40- 20- jjjh[ljL 40- TERRESTRIAL INSECTS 20- J Lk n •a: lOOn AQUATIC INSECTS LU Fig 10 —Average weight percentages of major foods S 50- found in small bluegill UJ (100-1 19 mm) from the intake and discharge arms of Lake Sangchris during different LlJ seasons of 1974 and 1975. g 20- lOOn ZOOPLANKTON 80- 6(H 40 20H I n H L 24 18 IS N-INTAKE 30 23 24 2a 20 t^-DISCHARGE JAN/FEB MAR/APR MAY/JUNE JULY/AUG SEPT/OCT NOV/DEC Aug. 1981 SuLE ET AL. : Food Habits of Fishes 517 Table 1 . — Frequency of occurrence of empty stomacfis in bluegllls during ihe 1974-1975 food- fiabits study. . 518 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 similar in both the heated and unhealed Gerkinc. S. D. 1962. Production and food utiliza- population of bluegill sunfish. arms of Lake Sangchris, indicating little tion in a Ecological Monographs 32:31-78. direct impact from the elevated water GoODSON. L. F.Jr. 1965. Diets of four warmwater temperatures. game fishes in a fluctuating, steep-sided. Califor- 8. — Because we found no direct nia reservoir. California Fish and Game evidence of the alteration of typical food- 51:259 269. Hoopes. D. T. 1960. Utilization of mayflies and habit patterns for the fishes studied, caddis flies by some Mississippi River fishes. this area should pursue future research in American Fisheries Society Transactions the relationship between food resource 89:32-34. production and use. Keast. a. 1978. Feeding interrelations between age-groups of pumpkinseed {Lepomis gibbosus) and comparisons with bluegill (L. macrochirus) Canada Fisheries Research Board Journal REFERENCES CITED 35:12-27. , and D. Webb. 1966. Mouth and body form Bailey. R. M., and H. M. 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Illinois voirs of Texas. III. Time of day and patterns of Natural History Survey Bulletin 32(4). Fisheries Society Transactions feeding. American Waite, S. W. 1981. effects of cooling lake 106:596 601. perturbations upon the zooplankton dynamics of Grossman. 1973. Scott, W. B.. and E. J. Lake Sangchris. Pages 342-357 in R. W. Freshwater fishes of Canada. Canada Fisheries Larimore and J. A. Tranquilli, eds., The Lake Research Board Bulletin 184. 966 p. Sangchris study: case history of an Illinois cooling 1964. Feeding Seaburc, K. C, and J. B. Moyle, lake. Illinois Natural History Survey Bulletin habits, digestive rates, and growth of some Min- 32(4). nesota warmwater fishes. American Fisheries habits of cat- Ware, F, J, 1967. The food channel Society Transactions 93:269 285. fish in south Florida. Southeastern Association of Shira, a. F. 1917. Notes on the rearing, growth, Game and Fish Commissioners Proceedings and food of the channel catfish, Ictalurus punc 20:283-287. tatus. American Fisheries Society Transactions Webb, D. W. 1981. The benthic macroinvertebrates 46:77-88. from the cooling lake of a coal-fired electric feeding SuLE, M. J. 1981. First-year growth and generating station. Pa,ges 358 377 in R. W. habits of largemouth bass in a heated reservoir. Larimore and J. A. Tranquilli, eds.. The Lake Pages 520-535 in R. W. Larimore and J. A. Sangchris study: case history of an Illinois cooling Tranquilli, eds.. The Lake Sangchris study: case lake. Illinois Natural History Survey Bulletin history of an Illinois cooling lake. Illinois Natural 32(4). Hisiorv Survey Bulletin 32(4), Welker, B. D. 1963. Summer food habits of yellow SwADENER, S. O., AND J. BucKLER. 1979. Benthic communities of Lake Sangchris and Lake bass and black bullheads in Clear Lake. Iowa Shelbyville. Pages 1-1-1-54 >n Evaluation of a Academy of Science Proceedings 69:286-295. cooling lake fishery. Vol. 4. Fish food resources ZwEiACKER, P. L.. and R. C, Summerfelt. 1974. studies. Prepared by Illinois Natural History Seasonal variation in food and diet periodicity in Survey for Electric Power Research Institute, feeding of northern largemouth bass, Palo Alto, CA, MicropteTus s. salmoides (Lacepede), in an reservoir. Southeastern Association of TRANduiLU, J.A.. R. KocHER, and J. M. McNurney. Oklahoma Sangchris Fish Commissioners Proceedings 1981 . Population dynamics of the Lake Game and fishery. Pages 413-499 in R. W. Larimore and J. 27:579-591. First-Year Growth and Feeding of Large- mouth Bass in a Heated Reservoir Michael Jay Sule ABSTRACT whose principal game and main Juvenile largemouth bass were sampl- predatory fish is the largemouth bass. ed 10 times during 1975 and two times Many factors have been reported to during 1976 from the intake (cool) and influence growth of bass, including sex, discharge (warm) arms of Lake population density, abundance of other Sangchris, Illinois. Bass grew larger in fishes, turbidity, oxygen concentration, the discharge arm, where the growing genetic characteristics, and parasites. season had been lengthened artificially. The influence of temperature and length Although bass from the intake arm had of growing season on bass growth is higher coefficients of condition than known to be especially important and has those from the discharge arm, none was been shown to vary considerably from in poor condition. Stomach analyses year to year and between fish from dif- generally indicated similar feeding in the ferent areas (Bennett 1937, Stroud 1948, two study areas and that feeding habits Kramer & Smith 1960, Mraz et al. 1961. depended strongly on the size of the bass Strawn 1961, and Clugston 1964). Equal- examined. The extended growing season ly important to temperature and growing in the discharge arm allowed juvenile season length are the food resources upon largemouth bass to make major length which fish growth depends. This study and weight gains, and become was developed to examine the first-year predominantly piscivorous during their growth and feeding habits of largemouth first growing season. bass in two areas of Lake Sangchris in an attempt to isolate any alterations in growth and feeding attributed directly to INTRODUCTION the thermal loading of the lake. The growth of a fish species during its first growing season may affect the sur- DESCRIPTION OF THE vival rate and, hence, the year class STUDY AREA strength of that species. Consequently, Lake Sangchris in central Illinois pro- first-year growth can strongly influence a vides condenser cooling water for the species' future growth and catch as well as Kincaid Electric Generating Station. The that of other fishes, and in the case of 876-ha lake (described in detail by largemouth bass, Micropterus salmoides, Larimore & Tranquilli 1981) consists of perhaps affect the population dynamics three narrow arms oriented approximate- for the entire fishery. Additionally, ly in a north-south direction with the growth and food habits data are valuable power plant between the upper ends of for fishery models, as well as for com- the middle and western arms. Warm parative evaluations of fish communities. water from the power plant is discharged For these reasons, describing the effects into a canal and then circulates in a cool- of a thermal discharge on the first-year ing loop through the middle arm growth of largemouth bass was an essen- (discharge arm) and the west arm (intake tial part of a comprehensive study of the arm) to the plant intake canal. Water in- fishery of Lake Sangchris, a heated lake creases in temperature by 7°-9°C as it passes through the power plant but is Michael J. Sule is with the Illinois Department of Conservation. Oregon. Illinois. back to ambient temperatures by the This chapter submitted in Jan. 1978. time it has traveled about halfway around 520 Aug. 1981 Sule: Growth and Feeding of Bass 521 . of Lake Fig. 1 —Sampling areas (shaded) for juvenile bass in the intake and discharge arms Sangchris, Illinois. the 16-km cooling loop. This design pro- September 1975, seven collections were vides an ideal situation for comparing made by seining along the shoreline. In biotic communities inhabiting areas that the first two collections a 6.1 x 1.2-m bag differ primarily in temperature. Conse- seine with 4-mm square mesh was used. quently, collection locations were The subsequent five collections were established in the intake and discharge made with a 6.1 x 1.2-m bag seine with arms of the lake to examine growth and 6-mm square mesh. All collections were feeding of young-of-the-year bass popula- made between 0900 and 1300 hours. tions in the lake's two extreme There was no significant difference temperature regimes (Fig. 1). between the mean length of fish collected by seining and those collected by elec- METHODS trofishing during the 3 September 1975 Young-of-the-year largemouth bass collection, so this collection and the were collected at approximately 3-week two subsequent samples included intervals from 29 May to 1 1 December specimens obtained by both techniques. 1975 from the intake and discharge arms From 17 October to 1 1 December 1975, of Lake Sangchris. Two additional collec- three additional collections were made by tions of young bass were taken in the sum- electrofishing along the shoreline. The 17 t mer and fall of 1976 for comparison of October 1975 collection was sup- bass growth between 1976 and 1975. plemented by fish collected from a cove Water temperatures were monitored in treated with rotenone within the sampl- both arms of the lake throughout the ing area in the discharge arm. On 14 July study period. From 29 May to 29 and 26 September 1976, samples were 522 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 collected by seining and electrofishing in RESULTS AND DISCUSSION both the intake and discharge arms of the lake. GROWTH Fish were placed on ice until accurate Surface waters in the discharge arm measurements were made in the were warmer than in the intake arm laboratory. Each fish was measured to the throughout most of the study period (Fig. nearest millimeter total length and 2). Water temperatures in the discharge weighed to the nearest 0.1 g. Fish arm of Lake Sangchris in the hottest part stomachs were preserved for analysis in a of the year rose above temperatures con- solution of 10-percent formalin. sidered preferred by bass. Since young Growth of young-of-the-year bass was bass were captured throughout the year analyzed by the length-frequency in the discharge arm, springs, coves, and method. Absolute growth was determin- sheltered weedy areas were probably used at as ed from the mean total length of fish cap- by bass times cooler refuge areas. tured on each sampling date. The ab- Surface water temperatures were record- ed at the site, solute growth in weight was also deter- sampling but isolated mined, as were length-frequency temperature anomalies within the sampl- distributions and length-weight relation- ing areas may have existed. ships. The coefficient of condition, K(TL), (Carlander 1969) was computed for each fish using formula (1): W X 10^ K(TL) = L' where, W is the weight of the fish in grams, and L is the total length in SEPTDBtR NOVDKR millimeters. AU6US1 OatKR KCE?RS Fish from both sampling sites were Fig. 2. —Surface water temperatures (°C) in separated into 5-mm size groups. For the intake and discharge arms of Lake Sangchris from May to December 1975, each date, stomachs of five fish from each size group were analyzed for food content. If one of those fish was found to Measurements were taken from 415 have an empty stomach, another fish largemouth bass collected from the from that size group was examined, when discharge arm and 705 from the intake possible, to insure a relatively large arm. Since accurate weights were not ob- sample of fish that contained food. tained for fish from the two collections in Stomachs were removed from fish by 1976 or the first two collections in 1975, severing the disgestive tract at the no K(TL) calculations or growth-in- anterior end of the esophagus and at the weight data for those dates were possible. posterior end of the stomach. Stomachs Length-frequency distributions were were then rinsed with alcohol and placed plotted in 5-mm size groups for fish col- on a clean petri dish where they were lected from 29 May to 13 August 1975 dissected and examined. Food items were (Fig. 3), and in 10-mm size groups for fish identified to the lowest possible taxon and collected from 3 September to 11 the proportion of each food item was December 1975 (Fig. 4). Length- determined by weight and recorded as a frequency distributions showed that two percentage of the total food matter (wet distinct populations of different sized weight) in each stomach. Although young-of-the-year bass were always pres- empty stomachs were found, all average ent in Lake Sangchris, and that bass from weight percentage calculations were the discharge arm were larger than these based only on stomachs that contained from the intake arm. food matter. All statistical comparisons Mean total lengths and weights were were made at the 5-percent probability calculated for fish from both arms of the level. lake (Table 1). Absolute growth curves Aug. 1981 Sule: Growth and Feeding of Bass 523 = DISCHARGE 29 MAY 1975 E INTAKE DISCHARGE N - 11 INTAKE N - 102 Fig. 3. — Length-frequency distributions for juvenile bass (5-mnn length groups) in Lake Sangchris from 29 May to 13 August 1975. 50 60 70 100 no 120 130 TOIAL LENGTH (mm) were drawn from the mean lengths of fish same areas in 1975; however, those size collected from each arm (Fig. 5). By 11 differences were only significant for December 1975, the lengths attained by September from the intake arm. This an- bass from the discharge arm were clearly nual difference may reflect the reduced greater than those from the intake arm. thermal loading experienced at Lake On each collection date, fish from the Sangchris during 1976 (Larimore & discharge arm were significantly larger Tranquilli 1981). than those from the intake arm. The rate Total lengths of bass at the end of the of growth in the first half of the growing 1975 growing season averaged about 100 season was not different, however, for fish mm and 140 mm from the intake and from the two arms. Although admittedly discharge arms, respectively. Although less extensive, the 1976 data indicated Carlander (1977) cited 134 mm as the that the 1975 growth trend had been average total length attained by repeated the following year. During both largemouth bass in Illinois by October- years, fish from the discharge arm were December of their first growing season, significantly larger than those from the the mean total length for bass from cen- intake arm. In general, bass collected in tral Illinois probably is somewhat less. 1976 were smaller than bass from the Carlander's estimate was based on several 524 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 a DlSCxARoe Aug. 1981 Sule: Growth and Feeding of Bass 525 E CO 0) o "O (0 o E (U Stb (/3 526 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 160 T 140 = DISCHARGE = INTAKE 120 i 100- HZ ^ 80- ^ 60- LU ao- 20- 1 ^ ' ^ DC J JC MAY JUNE JULY AU6UST SEPTEMBER OCTOBER NOVEMBER DECEMBER Fig 5 — Absolute growth in length of juvenile largemouth bass in Lake Sangchris from 29 May to 1 1 December 1975. IVIean lengths of bass on 14 July 1976 and 26 September 1976 are indicated by letters A (discharge arm) and B (intake arm). Numbers indicate sample size. 10-1 MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Fig. 6. —Absolute growth In weight of juvenile largemouth bass In Lake Sangchris from 3 July to 11 December 1975. Numbers Indicate sample size Aug. 1981 Sule: Growth and Feeding of Bass 527 Table 2. —Average coefficients of conditions [K(TL)] for young-of-the-year largemoutti bass col- lected from the intake and discharge arms of Lake Sangchris, Figures marked with an asterisk (") are significantly (5 percent) greater than the corresponding value for that date by t test. 528 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Table 3, —Average coefficients of condition [K{TL)] for young-of-the-year bass within 5 mm size groups collected from Lake Sangchris, 1975. Figures marked with an asterisk {*) are significantly (5 percent) greater than the corresponding value for that size group by Hest. Aug. 1981 Sule: Growth and Feeding of Bass 529 length. A total of 35 (10.7 percent) Composition of the aquatic insects con- stomachs of fish from the intake arm were sumed by bass in the intake arm consisted empty, while 59 (16.8 percent) of those mainly of ephemeropterans (40.5 per- from the discharge arm were empty. cent) and zygopeterans (37.3 percent), Food items found in juvenile largemouth while chironomids comprised a relatively bass stomachs are listed in Table 4. small (11.5 percent) portion of the total Food habits were quite varied, and aquatic insects ingested. In the discharge utilization of food organisms differed arm, aquatic insect consumption was with respect to size of the fish examined divided among zygopterans (25.6 per- and date of collection (Tables 5 and 6). cent), ephemeropterans (20.0 percent), Bass from both arms of the lake, corixids (20.2 percent), chironomids however, fed essentially on the same food (16.6 percent), and anisopterans (9.9 items, aquatic insects, fishes, and percent). zooplankton. All zygopterans indentified were In both areas, aquatic insects were the Enallagma spp. Most Ephemeroptera most important food resource. An found were Callibaetis spp., along with a average of 47.7 percent and 38.3 percent few Hexagenia spp. and Caenis spp. of the stomach contents (wet weight) of Cricotopus spp. and Xenochtronomiis bass from the intake and discharge arms, spp. were the most frequently ingested respectively, consisted of aquatic insects. chironomids. No single anisopteran was Table 4- -Common food items of young-of-the-year largemouth bass in Lake Sangchris during 1975. Aquatic Insects 530 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 (OOini^iOCTlt^^-'OOOOC^lCsl^inCTiOC — o-^o ^ ^ .,}* ^ ^ o o in o o OOOOOQOlC.-'onoOOOOOOOCJ>000000 O GO O oo oo O O if)inOQ0cr).-^c^ooooo»r)O o o in © in o o in 00 * (N o o W O CM in^ooooc^i^o^OinooinogO'-'frJOO in ^ 04 — — •«. m IT) eo oo O 9 c o E B D o o a> m 5 X3 Aug. 1981 Sule: Growth and Feeding of Bass 531 CMOtNQOvOr^cncOOO^-r^C^cOOlI^ Tj^O O ^-i CO o ^ « CO 5OO(Mc0O00OOOOO(MOO o c wro E o o O) CO £1 532 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 found more frequently than any other. lake. When a cladoceran species was the Bass from the intake and discharge arms predominant prey of bass in one arm, it showed little difference in species also tended to be the predominant preference for most taxa. Different Cor- cladoceran prey in the other arm. ixidae, however, were used in the two Seasonal pulses of different species of zoo- study areas. Trichocorixa calva plankter may have developed predominated in fish from the discharge simultaneously in the two arms of the arm while Palmacorixa spp. was found lake, or the water current associated with most often in bass from the intake arm. the cooling loop of Lake Sangchris may Distributional differences of these two have tended to reduce species segregation corixids in Lake Sangchris may have ac- between the two arms. Some cladoceran counted for their differential usage by species, however, were known to occur bass; however, Webb (1981) did not col- throughout the year in both arms of the lect corixids in sufficient numbers in his lake (Steve Waite, Illinois Natural benthic samples to confirm this History Survey, personal communica- hypothesis. Aquatic insects other than tions) but were consumed by bass mainly those mentioned above were also utilized during a particular time of year. The in both arms, but made a comparatively data indicated that small, round small contribution to the overall diet. cladocerans, such as Bosmina longirostris Those littoral-dwelling macroinverte- and Chydorus sphaericus, were used early brates indicate that bass were feeding in in the year when bass were small. Later in vegetated, shallow areas of the lake. the year when bass were larger, bigger cladocerans such as Simocephalus ser- Fish accounted for 25.7 percent (by rulatus, Daphnia parvula, Sida weight) of the diet of bass from the intake crystallina, and Diaphanosoma arm and 29.8 percent of the diet of bass leuchtenbergianum were the predomi- from the discharge arm. Bluegills, nant cladocerans consumed. In general, Lepomis macrochirus, were the most fre- the species of Cladocera consumed by quently identified fish in samples from bass are typically found in shallow both study areas; however, most fish were vegetated areas, indicating the type of too digested for identification. Fish habitat in which bass fed. utilization by bass from the intake arm Bass consumption of terrestrial and was equal to or greater than that in the aerial insects was typically low (intake 2.8 discharge arm until the last three collec- percent, discharge 12.3 percent). tions of 1975, at which time consumption Predominant in this food category were of fish by bass in the discharge arm in- emergent aquatic insects. Zygoptcran creased considerably. adults accounted for an average of 42.8 Zooplankton accounted for an percent and 26.6 percent of the weight average of 16.2 percent of the food mat- ingested of this food category in the in- ter of bass from the intake arm and 13.0 take and discharge arms, respectively. As percent for those from the discharge arm. in the nymphal stages, Enallagma spp. In both study areas Cladocera constituted was the only adult zygopteran found. the major portion of the zooplankton The most obvious trend in the food consumed (65 percent in the intake arm habits was the shift in food selection and 79 percent in the discharge arm) which occurred with changes in bass total while Copepoda made up the remainder. length (Fig. 7). Bass of comparable size Several species of Cladocera were of ma- used the same type of food resources in jor importance in the composition of similar quantities in both the intake and zooplankton used as forage. Those species discharge arms. Bass from 18 to 50 mm most frequently found in stomachs were fed heavily on zooplankton. Chironomids Bosmina longirostris, Scapholeberis were also frequently eaten by small bass kingi, Simocephalus serrulatus, and Sida but were utilized to some extent by fish as crystallina. Those species were used in large as 130 mm. Other aquatic insects similar quantities in both arms of the were utilized over a broad range of bass Aug. 1981 Sule: Growth and Feeding of Bass 533 Fig. 7 —Average weight percentage of major food categories utilized by young- of-the-year bass of different lengthis in Lake Sangcfiris dur- ing 1975. 10 20 30 W SO 60 70 30 90 100 110 120 130 140 150 160 170 180 190 2CK) 210 TOTAL LENGTH Of BASS Im) sizes and generally in great quantities. 66 mm in length fed on insects and Dependence upon this food source was plankton while larger bass primarily ate greatest for bass between 40 mm and 140 fish. mrr in total length. Terrestrial and aerial Since bass from both areas of Lake insects were mainly consumed by bass Sangchris exhibited similar food habits, it between 70 mm and 170 mm. Consump- was hypothesized that differences in tion of these types of insects, however, growth rates near the end of the normal was generally lower than consumption of growing season resulted from decreased aquatic insects or fish. While fish were feeding in the intake arm. Although bass used as a food resource by bass as small as in the discharge arm continued to grow 22 mm, they were not a consistantly im- rapidly late in the season while those in portant food item until bass reached a the intake arm did not, the percentage of total length of 90-100 mm. As bass in- empty stomachs in bass from the two creased in length, there was a general in- study areas did not support the hypothesis crease in the utilization of fish as food. consistently. However, the frequency of These findings agree well with Keast & empty stomachs may not be a reliable in- Webb (1966) who found that young bass dicator of feeding rate, since factors such from 30 to 50 mm had a diverse diet of as the time of collection, rate of diges- Cladocera, Ephemeroptera, Amphipoda, tion, and type of food consumed also and Chironomidae, while fish were not need to be considered when evaluating predominant in the diet until bass reach- growth. Greater predation on fish by bass ed a length of 80 mm. These data are also from the discharge arm from 17 October similar to those reported by McCammon through 11 December 1975 probably was et al. (1964) who found that bass less than paramount in affecting late season bass 534 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 growth. Bennett (1948) stated that, as 3. — Growth rates were similar for food items for bass in Illinois, Cladocera juvenile bass in the two study areas and aquatic insects were not conducive to throughout most of the study period, ex- rapid growth when compared to fish or cept near the end of the normal growing crayfish. The higher growth efficiency season when bass in the discharge arm associated with consuming fish matter continued to grow rapidly while those in and the higher fish metabolism in the the intake arm did not. warmer water may well have accounted 4.— Condition factors of bass were for the faster growth rate of bass in the lower in the discharge area, possibly discharge arm during the last part of the associated with higher metabolic rates of 1975 growing season. The greater size of fish in the warmer water. Bass were not young-of-the-year bass in the discharge considered in poor condition in either arm by the end of the normal growing area. season was a result of the size advantage 5.— The composition of the stomach initiated earlier in the year and maintain- contents was closely correlated with the ed throughout the growing season. Con- size of bass examined. Small bass from sequently, even with similar feeding both areas fed heavily on zooplankton, habits exhibited throughout most of the while larger bass shifted initially to year by bass from the intake and aquatic insects and later to fish. discharge arms of Lake Sangchris, the 6. — The extended growing season in normal shift of larger bass to a more the discharge arm consequently allowed piscivorous habit helped stimulate growth more young bass to grow to a of bass in the discharge arm during the predominantly piscivorous size during latter part of the year. Since bass in the their first year of life. discharge arm were larger and could utilize the more highly efficient fish diet, bass from that area were able to benefit REFERENCES CITED both from their size advantage and the thermally extended growing season in the Bennett, D. H., andj. W. Gibbons. 1974. Growth fall. and condition of juvenile largemouth bass from a thermal effluent. Pages First-year growth increases offer many reservoir receiving 246-254 in W. Gibbons and R. R. Shariu, possible benefits to both fishermen and J. ed., Thermal ecology. AEC S\Tnposium Series resource managers. Enhanced growth (CONF-730503). Augusta. GA^ probably offers survival advantages for Bennett, G. W. 19S7. The growth of the large bass as well as producing a more efficient mouthed black bass, Huto salmoides (Lacepede). the waters of Wisconsin. Copeia (2):104-118. fish predator. Earlier recruitment into in 1948. The bassbluegill combination in a the fishable bass stock is another possible small artificial lake. Illinois Natural History merit of thermal enrichment that might Survey Bulletin 24(S):377-412. increase the fishing pressure that a body BuSACKER. G. P. 1971. The age and growth of the of water could withstand. largemouth bass, Micropterus salmoides (Lacepede), in a thermally loaded reservoir. MA. Thesis, University of Missouri, Columbia. SUMMARY Carlander, K. D. 1969. Handbook of freshwater fisherv biology. Volume I. The Iowa State Press, Ames. 752 1.— On each collection date, juvenile University p. . 1977. Handbook of freshwater fishery bass from the warmer discharge arm had biology. Volume II. The Iowa State University weights sigfnificantly greater lengths and Press, Ames. 431 p. P. of the Florida large- than those from the cooler intake arm. Clucston. J. 1964. Growth mouth bass, Micropterus salmoides floridanus I 2.— Since bass in the discharge arm (LeSueur). and the northern largemouth bass. M. | were spawned earlier and continued to s. salmoides (Lacepede), in subtropical Florida. grow later in the season than those in the American Fisheries Society Transactions 93(2): 146-154. intake arm, the elevated temperatures in Joy T. 1976. Lake Shelbyville fish populations. the heated area extended the actual Pages 4.12-4.30 in R. W. Larimore and J. M. growing season for bass residing there. McNurney, eds.. Evaluation of a cooling lake Aug. 1981 Larimore & Tranquilli, Eds. : The Lake Sangchris Study 535 fishery. First annual report by Illinois Natural Strawn, K. 1961. Growth of largemouth bass fry at History Survey to electric Power Research In- various temperatures. American Fisheries Society stitute, Palo Alto. Ca (unpublished). Transactions 90(3):334-335. Keast, a., and D. Webb. 1966. Mouth and body Stroud, R. H. 1948. Growth of the basses and black form relative to feeding ecology in the fish fauna crappie in Norris Reservoir, Tennessee. Ten of a small lake, Lake Opinicon, Ontario, Canada nessee Academy of Science Journal 23(l):3I-99. Fisheries Research Board Journal Tranquilli, A., R. Kocher, 23{12):1845-1874. J. and J. M. Mc NuRNEY. 1980. Population dynamics of the Lake Kramer, R. H., and L. L. Smith, Jr. 1960. First- Sangchris fishery. Pages 413-499 in year growth of the largemouth bass, Micropterus R. W. Larimore and A. Tranquilli, salmoides (Lacepede), and some related J. eds., The Lake Sangchris study; case history of ecological factors. American Fisheries Society an Illinois cooling lake. Illinois Natural Transactions 89(2):222-233. History Survey Bulletin 32(4). Larimore, R. W., and J. A. Tranquilli. 1981. The Lake Sangchris project. Pages 279-289 in Trembly, F. J. 1965. Effects of cooling water from R. W. Larimore and J. A. Tranquilli, eds.. The steam-electric power plants on stream biota. Lake Sangchris study: case history of an Illinois Pages 334-345 in Biological problems in water cooling lake. Illinois Natural History Survey pollution. Third Seminar 1962. U. S. Public Bulletin 32 (4). Health Service Publication 999 WP 25. McCammon, G. W., D. A. LaFaunce, and C. M. Webb, D. 1981. The benthic macroinvertebrates Seeley. 1964. Observations on the food of from the cooling lake of a coal-fired electric fingerling largemouth bass in Clear Lake, Lake generating station. Pages 358-377 in R. W. County, California. California Fish and Game 50 Larimore and A. Tranquilli, eds.. The Lake (3):158-I69. J. Sangchris study: case history of an Illinois cooling Mraz, D., S. Kmiotek, and L. Frankenburcer. lake. Illinois Natural History Survey Bulletin 1961. The largemouth bass, its life history, 32(4). ecology, and management. Wisconsin Conserva- tion Department Publication 232. 15 p. Results of a Multiple-Objective Fish-Tagging Program in an Artificially Heated Reservoir John A. Tranquilli, John M. McNumey, and Richard Kocher ABSTRACT Stations in the discharge and intake areas traveled significantly farther than did A multiple-objective fish-tagging bass from stations in the middle of the program was conducted from 1974 to cooling loop, perhaps because those 1976 to obtain data on largemouth bass, habitats represented extreme thermal carp, and white bass that could not be conditions and the fish at those sites may obtained by other methods and to clarify have been seasonally attracted to or some conflicting results regarding fish repelled from thermal gradients in the growth, movements, and population lake. in other fishery densities found Movements by all three species power investigations of Lake Sangchris, a between heated and unheated areas had plant cooling lake. Including multiple no effect on their average growth in and fish recaptured without recaptures length or weight, but larger individuals 38.4 percent of the tags (marks only), grew more rapidly than smaller ones. the 2,390 largemouth bass, 8 percent of Composite growth data obtained from 1,492 carp, and 5.6 percent of the 1,133 recapture records showed that were subsequently recovered. white bass largemouth bass and white bass growth Largemouth bass populations were was rapid, but that little, if any, carp mark-and-recapture estimated by growth had occurred. with 95 percent confidence to be methods The effects of thermal discharge on fish > 150 mm in total 11,561 ± 2,952 annulus formation by largemouth bass in 1974 and 9,444 ± 1,700 length in cooling lakes was examined by comparing in 1975. From these fish>200 mm scales taken from the same fish at the an average standing crop of 8.8 estimates time of tagging and again upon determined. In 1976 the kg/ ha was recapture. Annulus formation occurred carp was estimated with 95 number of during the spring, but false annuli were percent confidence to be 13,194 ± 2,408 especially common in fish from the > total length, or a fish 275 mm in heated area and could not easily be standing crop of 20.0 kg/ha. distinguished from true annuli. Analyses of fish movements indicated Consequently, interpretation of annual between the size of the no relationship growth from marks on scales was not and the distances they fishes tagged suggested for cooling lake bass traveled. The grand mean for distances populations in this region of the USA. traveled by fish from all areas of the lake combined was 5,845 m for white bass, INTRODUCTION 1,635 m for largemouth bass, and 1,389 A multiple-objective fish-tagging m for carp. Largemouth bass tagged at program was initiated as part of a broad thermal effects at Dr. John A. Tranquilli is an Associate Aquatic ecological study of Biologist in the Section of Aquatic Biology, Illinois Lake Sangchris. The tagging studies were M. McNurney is Natural History Survey: John initiated to obtain data that could not be with R.W. Beck and Company. Denver. Colorado; obtained by other methods and to clarify and Richard Kocher is with the Wabash Production results regarding fish Credit Association. Robinson. Illinois. some conflicting population This chapter submitted in Nov. 1979. growth, movements, and 5S6 Aug. 1981 Tranquilli et al. : Fish Tagging 537 densities obtained in other fishery recognized as belonging to a group tagged investigations of this cooling lake. during a specific year. Gross movement Largemouth bass (Micropterus between stations could be determined for salmoides), carp (Cyprinus carpio), and recaptured fish that had lost their tags if white bass (Morone chrysops) were they were in the group tagged and tagged. Objectives of the study included: marked during 1974. (1) estimation of population size and To equalize the distribution of tagged standing crops, (2) comparison of fish in relation to their population densi- composite growth of each species relative ty, largemouth bass and carp were cap- to its movements among heated and tured throughout the lake by using an unheated areas, (3) quantitative analysis alternating-current electrofishing ap- of fish movements within different paratus. In 1974 and 1975, total lengths thermal regions, and (4) determination of of 150 and 200 mm, respectively, were thermal discharge effects on annulus selected as minimum sizes of largemouth formation. bass to be tagged. A total of 1,035 largemouth bass was tagged in 1974, and METHODS 1,355 in 1975; 439 carp were tagged in 1975, and 1,053 in 1976. From 1974 to From 1974 to 1976 a total of 5,015 1976, largemouth bass and carp were tag- fish (2,390 largemouth bass, 1,492 carp, ged between 13 April and 15 May. White and 1,133 white bass) was captured from bass were captured by hook and line or Lake Sangchris, tagged, and released with a direct-current electrofishing ap- within 100 m of the original points of paratus in the discharge canal only. The capture. Each fish was tagged with an direct-current apparatus was used individually numbered Floy anchor tag because we observed poor recovery from (Model FD-67 in 1974 and Model FD-68B electronarcosis with an alternating- in 1975 and 1976). The tags and current electrofishing apparatus. In applicator are described by Dell (1968). 1975, 200 white bass were tagged between The tags were inserted diagonally, as he 9 April and 18 April, and in 1976, 933 suggested. In 1974 each tagged fish was white bass were tagged between 27 given two permanent marks (fin clips) to February and 8 May. indicate the area of the lake (station) and During all 3 years of the study, fish year in which tagging occurred. In 1975 captured for tagging were processed in and 1976 each tagged fish was given only small groups (10 — 20 fish) to reduce one permanent mark to indicate the year handling stress. The release locations of tagging. From such distinctive marks, were carefully noted on detailed maps so fish that lost their tags could always be that movements of individual fish could Fin-clipped white bass tagged with an anclior lag. 538 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 be determined accurately. The anchor al. (1962) had previously used an electric end of the tag was inserted between the shocker in conjunction with mark-and- interneural rays near the posterior end of recovery methods to estimate populations the dorsal fin with the colored informa- of largemouth bass. The rationale is that tional end of the tag trailing outside of the total population size is related to the the fish. The tags instructed fishermen to number marked and released in the same report their catch by telephone to the Il- way as the total caught at a subsequent linois Natural History Survey. The sex of time is related to the number of marked each mature fish was determined at the fish recaptured. This relationship was ex- time of tagging by external examination. pressed mathematically according to this The fish was sexed again upon recapture. equation (Robson & Regier 1971): Each fish was weighed, measured, and A = marked permanently with a fin clip prior N mc/r Where to being tagged with a Floy anchor tag. A N = total number of fish in popula- series of scales was taken from each fish tion (unknown) during the tagging process and stored in individual envelopes. m = total number of marked fish in population (known) An attempt was made to collect as c = number of fish in subsequent much information as possible on each sample recaptured fish. For each recapture, the = fish recap- method of recapture and the method of r number of marked information retrieval was recorded. Only tured in sample lengths and weights of recaptured fishes N = estimate of N measured by biologists were used in the The 95-percent confidence limits were analysis of fish growth. The highly ir- approximated by adding two standard er- regular shoreline of the lake, with many rors to the estimate and subtracting two distinctive coves and landmarks, permit- A from it. The standard error of N was ted very accurate location of recapture estimated by the following equation: sites. The shortest distance from point of release to point of recapture was A A on large aerial photograph of (^— ^^^.--^ measured a sE(f:)) = f^/ A the lake to determine the distance travel- V/ mc (N- 1) ed by individual fish. The distances The mark-and-recapture methods tagged fish were determined traveled by were based on these assumptions (Ricker only from those fish recaptured with in- 1958): (1) marked fish did not lose their tact tags. retention rates were deter- Tag identifying marks (fin clips) throughout mined from the number of marked fish of the study period, (2) marking effort was species recaptured with tags each each proportional to the density of the popula- month. tion throughout the body of water or For descriptive purposes, and to com- marked individuals were randomly pare growth and movements of fishes tag- distributed in the population, (3) marked ged in different regions, the entire lake and unmarked fish were equally suscepti- was divided into eight contiguous stations ble to capture, (4) numbers of fish were increased via recruitment from (Fig. 1). Stations 0. 1, 2, 7, and 8 not represented regions with unheated water, growth or immigration, and (5) losses the and stations 3, 4, and 5 represented through death or emigration were regions with heated water for some com- same for both marked and unmarked parisons. No fish were tagged at Station fish. 6, the slag pond adjacent to the power The effect of thermal discharge on plant, because it is not part of the lake. annulus formation by largemouth bass Population estimates for largemouth was studied by comparing growth marks bass and carp were based on Petersen on scales taken from each fish at the time mark-and-recapture methods. Lewis et of tagging with gfrowth marks on scales Aug. 1981 Tranquilli et al. : Fish Tagging 539 Fig. 1 . — Lake Sangchris, showing stations for fish-tagging studies. Shaded zones represent areas where largemouth bass were tagged in 1974. In subsequent years largemouth bass and carp were tagged aiong the entire shoreline of the lal taken from the same fish when it was pare distances traveled by fish tagged in recaptured. The scales were cleaned in different areas of the lake, an analysis of water and impressions were made of the variance was used with initial length and scales in acetate by means of a roller press time as covariables (Table 13). When (Smith 1954). The acetate impressions significant differences were found, a were viewed on an Eberbach scale projec- Duncan multiple range test was used to tor at 40 X magnification. compare the means. The relationship Data were analyzed by species using between fish gfrowth and movements Statistical Analysis System (SAS) pro- within and between heated and unhealed the lake cedures (Barr et al. 1976) on an IBM portions of was examined by an analysis that year 360/75 computer at the University of Il- of variance used of linois, Urbana. The frequency program recapture and size (initial length and (FREQ) within SAS was used to compile weight) as covariables (Tables 15 and 16). methods of recapture and information retrieval, to determine tag retention RESULTS AND DISCUSSION rates, to categorize movements be- and METHODS OF RECAPTURE AND tween stations. A one-way analysis of INFORMATION RETRIEVAL variance, using initial size as a covariable, was used to compare distances traveled by From the 5,015 fish tagged and mark- male and female fish (Table 10). To com- ed in Lake Sangchris from 1974 to 1976, 540 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 1,100 recapture records were obtained counted for approximately equal propor- (Table 1). Sport fishing (49.8 percent) tions of the 918 largemouth bass and electrofishing (48.5 percent) ac- recoveries. For carp, electrofishing ac- £? o 6? S? 6? O be 6? a IS =8 S pa < SS 1 Aug. 1981 Tranquilli et al. : Fish Tagging 541 counted for a much gfreater proportion percent) of the 1,100 recoveries resulted (84 percent) of the 119 recoveries than from samples collected by field biologists did sport fishing (10.9 percent), while for (Table 2). Sport fishermen reported 187 white bass, sport fishing accounted for a tagged fish (17.0 percent) to the creel greater proportion (58.7 percent) of the clerk, reported 189 (17.2 percent) by 63 recoveries than did electrofishing (1 1 . telephone, and took 55 (5 percent) to the percent). Other methods offish recapture field laboratory. included the use of bow and arrow, ex- Of the 2,390 largemouth bass tagged perimental gill nets, rotenone in standing and marked in 1974 and 1975, 649 (27.2 crop surveys, and hoop nets as well as the percent) (including multiple recaptures) recovery of dead fish. None of those were recaptured with intact tags and 269 recovery methods was important for (11.3 percent) were recaptured without largemouth bass or carp, but gill nets and tags (Table 3). A total of 918 tagged and recovery of dead fish were important for marked largemouth bass were recaptured white bass. Gill nets (6.3 percent) prob- for a total recovery rate of 38.4 percent. ably accounted for a greater percentage Excluding multiple recaptures of of the 63 white bass recoveries than of the largemouth bass and fish without tags, a largemouth bass and carp recoveries total of 583 individuals were recaptured, because of the pelagic nature of the white yielding a recovery rate of 24.4 percent. bass. The relatively high proportion of The recovery rate of largemouth bass was white bass recovered dead (23.8 percent) more than three times greater than that may be indicative of the inability of that for either carp or white bass. species to handle the stress of capture (1) Including multiple recaptures and by electrofishing or hook and line, (2) the fish recaptured without tags in 1975 and marking and tagging procedure itself, or 1976, only 119 (8 percent) of the 1,492 tagging during its spawning migra- (3) tagged and marked carp and 63 (5.6 per- tion, which probably is a very demanding cent) of the 1,133 white bass were period in its life history. recovered. A greater proportion of the Fishes were recaptured for informa- tagged largemouth bass were recovered tion retrieval by field biologists who because they were easily captured by elec- sampled the fish population or by sport trofishing, there was an excellent sport fishermen who reported tagged fish to a fishery for that species in Lake Sangchris, creel clerk, took them to the field and the help of largemouth bass sports- laboratory, or reported them by men's clubs in the immediate area was telephone. Considering the three species solicited. In contrast, very few carp were of fish together, the majority (669, 60.8 captured by sport fishermen, and white Table 2. — Methods of information retrieval from tagged and marked fish recaptured in Lake Sangchris. 542 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 3, —Numbers of tagged and marked fish recaptured from Lake Sangchris with tags present (including multiple recaptures, i.e 1x, 2x, etc.) or absent and percentages of recovery. Number Recaptured Fish Species and Aug. 1981 Tranq^uilli ET AL.; Fish Tagging 543 1974 LARGEMOUTH BASS STUDY ° ill '\ H H R 1975 LARGEMOUTH BASS STUDY i-g zz n aaui 1975 CARP STUDY Fig. 2, —Tag retention rates determined from the percentage of tagged and 2 marked fishes recovered 043 I 202030 2 10 2 each month with intact tags. 1976 CARP STUDY The total number of fish examined each month is shown at the base of the histogram. 1975 WHITE BASS STUDY 100 1976 WHITE BASS STUDY 100- 1-1 n AMJJASONOJFMAMJJA MONTH In 1975, carp were tagged with FD-67 were 100 percent after 6 months and 87 tags that were reinforced with a rubber- percent after 1 year (Fig. 2). It was dif- base glue. The additional glue corrected ficult to make broad comparisons be- the tag failure problem . The tag reten- tween species because the performance of tion for carp tagged with modified FD-67 the tags was so variable, but it did appear tags during 1975 was 100 percent after 6 that carp retained tags somewhat better months and 83 percent after 1 year (Fig. than largemouth bass, possibly because 2). the skin beneath their scales appeared to The manufacturer was informed of be much tougher. Both Bryant & Houser our problems with the FD-68B tags in (1971) and Zweiacker (1972) tagged 1975 and the order was replaced. largemouth bass with similar Floy anchor Thereafter, we had no problems with tags and apparently experienced no prob- tag separation. The replacement FD- lems with tag separation. 68B tags were used to tag carp and white Kimsey (1956) and Chadwick (1966) bass in 1976. Tag retention rates for carp have compiled data that show how 544 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 various marking and tagging procedures 1976 were not attempted because the may significantly alter the growth and marking effort occurred exclusively in survival of a particular fish species and the discharge canal, and therefore mark- thus invalidate research results. Conse- ed individuals may not have been ran- quently, Tranquilli, McNurney, & domly distributed throughout the lake. Kocher (1979) conducted studies in small In 1974, 1,035 largemouth bass _>: 150 ponds under controlled conditions to in total length were tagged in April determine the effect of the type of tags mm and May. The recapture sample (c) ex- and marks used in this study on the tended through October of that year and growth and survival of largemouth bass recruitment (by growth) of fish into the and carp. We found no significant dif- population of marked fish was accounted ference (0.05 level) in the growth of ex- for by calculating the growth of 150-mm perimental fishes (tagged and fin clipped) fish from length frequency distributions. and control fishes, and the survival of the the experimental groups was 100 percent. Of 592 fish examined in the recap- ture samples, 53 were identified by These results indicated that the tagging marks and/or tags as belonging to the and marking procedures used at Lake 1,035-fish sample tagged in April and Sangchris probably had no effect on the May. estimated size of the growth or survival of largemouth bass or The population carp. largemouth bass of Lake Sangchris during spring, with 95-percent Zweiacker (1972) used similar tags to confidence limits, was 1 1,561 ± 2,952 fish study largemouth bass in Lake Carl ^150mm (Table 4). The estimate was Blackwell, Oklahoma, and found that equivalent to 13.2 bass per hectare in this the calculated condition factors were not 876-ha lake. The mean weight of the significantly different between recap- 1 ,035 largemouth bass at the time of tag- tured tagged fish fish without tags. and ging was 0.709 kg. Multiplication of the These results indirectly indicated that population estimate by the mean weight the tags did not affect fish growth. While provided an estimated standing crop of white bass were in tagged Lake 9.4 kg/ha for largemouth bass^l50 mm. Sangchris, we did not examine the effects of tagging and marking this species Only largemouth bass 200 mm or under controlled pond conditions. more in total length were marked and Although no effects were found on the tagged during 1975. As in 1974, the growth and survival of largemouth bass recapture sample was taken over a or carp, we would not assume, without 6-month period and recruitment was ac- testing, that the same result would be counted for by relating the growth of _>_ found for white bass. Field observations 200-mm fish to length frequency distribu- of tagged white bass indicated that they tions. Of the 1,355 tagged and/or mark- did not react well to handling, and we ed fish, 98- individuals were subsequently suspect that tagging mortality for that recognized in the recapture sample of 683 species may have been substantial. bass (Table 5). The estimated size of the spring 1975 largemouth bass population, with 95-percent confidence limits, was MARK-AND-RECAPTURE 9,444 ± 1,700 fish ^200 mm. This ESTIMATES OF POPULATIONS estimate was equivalent to 10.8 fish per AND STANDING CROPS hectare. The average weight of the bass Population estimates of largemouth tagged in 1975 was 0.752 kg, somewhat bass in Lake Sangchris during 1974 and larger than the average size marked in 1975, and of carp during 1976 were 1974, when the minimum length of the calculated by mark-and-recapture tagged fish was 50 mm less. Multiplica- methods. In 1975, too few carp were tion of the population estimate by the marked and recaptured to permit average weight gave an estimated stan- estimation of that population. Estimates ding crop of 8.1 kg/ha for largemouth of white bass populations in 1975 and bass ^200 mm. Aug. 1981 Tranquilli et al. : Fish Tagging 545 Table 4.— Population estimate for largemouth bass (> 150 mm in total length) in Lake Sangchris during 1974. Number of Marked Number of Fish Fish Recaptured Month in Sample (c) in Sample (r) Recruitment^ May 139 July September October Total A N = 546 Aug. 1981 Tranquilli et al. : Fish Tagging 547 Table 7. —Mark-and-recapture locations for largemouth bass tagged in Lake Sangchris during 1974 and 1975, illustrating direction of movements. The number and percentage (in parentheses) recaptured at each station are shown. Station 548 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 9. — Mark-and-recapture locations for white bass tagged In Lake Sangchrls during 1 975 and 1 976. Illustrating direction of movements. The number and percentage (In parentheses) recaptured at each station are shown. Station Aug. 1981 Tranquilli et al. : Fish Tagging 549 Table 10. —Analysis of variance comparing the mean distances traveled by male and female largemoutti bass, carp, and white bass tagged and recaptured in Lal Table 12. —Mean distances in meters traveled by fishes in Lake Sangchris in relation to the area (station) at which they were originally tagged, the number of fish in each sample (N), the mean distance moved ± the standard error, the range of distances, the mean time interval (in days), and the mean total length (In mm) of the recaptured fish (for which these data were available) are given. Species and Station Aug. 1981 TRANtiUILLI ET AL.: FiSH TAGGING 551 not be made for white bass, since all were Moody (1960) reported that 61.9 percent tagged in one area. Significant dif- of 189 recaptures occurred within 10 ferences (0.01 level) were found between miles (16,100 m) or less of their points of distances traveled by largemouth bass from different areas but not for carp 3 u bo (Table 13). Comparisons of station means t;; -c bo 2 > M revealed that largemouth bass tagged in the discharge (Station 5) and intake (Sta- tion 1) arms traveled significantly (0.05 level) farther than bass from stations 2 or 3 in the middle region of the cooling loop (Table 14). In a cooling lake, water cur- rents created by pumping are most evi- Q.S dent at the intake and discharge areas. bo These two areas are also characterized by B '5. having the greatest temperature differen- 3 tial. Fish tagged in those areas may have traveled farther because those habitats represent extreme thermal conditions; consequently, those fish may have been o seasonally attracted to or repelled from CD thermal gradients in the lake. Cm? O t- 4; ^ o; bo ^ 00 0<^ ift (N ^ t^ i:; X bo In a review of the literature dealing 2 > « t« with movements of tagged largemouth bass, it soon became apparent that the T3 0) amount of movement observed was >t limited by the physical characteristics of 2 a in the aquatic habitats studied (ponds, tagging in Lake George on the St. John's (H-H) tagged and recaptured in the River in Florida. He suggested that the heated area. For comparison, we assum- Lake George population consisted of a ed that fish tagged and recaptured within resident segment with restricted range the same thermal area remained there and a mobile group that tended to move during the interim period. To compare more freely through the St. John's River. the growth of fish with different thermal In an 8.4-acre (3.24-ha) farm pond in Il- histories and of different sizes, all fish of linois, Lewis & Flickinger (1967) found each species were adjusted to a common that 96 percent of the 96 recaptures oc- initial size by analysis of covariance. The curred within 300 feet (91 m) of the initial size (length and weight) of the fish original point of capture. Rawstron was tested as an independent variable af- (1967) observed that bass moved very lit- fecting mean annual growth. Results tle in Folsom Lake, California, averaging were presented as least-squares means, only 0.7 mile (1,126 m) from point of tag- which are averages adjusted to a common ging to point of recapture. In Lake Carl sample size and modified by covariable Blackwell, Oklahoma, Zweiacker (1972) effects. reported that 92.2 percent of the bass Sample sizes for the growth analyses were recaptured in the area where tag- of largemouth bass, carp, and white bass ged. Gibbons & Bennett (1973) followed were 181, 78, and 14 fish, respectively. movements of bass in Par Pond, a reser- For comparison of mean annual growth, voir receiving heated water, and conclud- common initial lengths and weights were ed that bass were highly mobile with 365 mm and 821 g for largemouth bass. travel of more than 6,000 m being of fre- 504 mm and 1,605 g for carp, and 300 quent occurrence. mm and 363 g for white bass. Results of the two-way analyses of IN GROWTH HEATED AND variance revealed that movements within UNHEATED AREAS and between heated and unheated areas The annual growth of tagged fish in had no effect on growth in length or Lake Sangchris was studied in relation to weight for any of the three species (Tables movements within and between heated 15 and 16). These data suggested that and unheated areas. For this analysis, growth was similar for fish which remain- recapture data for each species were used ed in heated or unheated areas of the to describe the composite growth of the cooling lake. If food resources were population of tagged fish, which con- similar throughout the lake, the greatest sisted of individuals of various sizes and growth advantage would occur for those ages. The annual growth of largemouth fish that moved to the thermally affected bass of specific size in Lake Sangchris was area during early spring, avoided that determined from recapture records and zone during the summer, and returned to was described in a separate study (Joy & it during the fall, thus benefitting from Tranquilli 1979). an extended growing season. Since we Composite growth data obtained could not detect that kind of detailed from taggfing records were analyzed in movement with this tagging procedure, relation to movements of fish within and we could not test that hypothesis. between heated and unheated areas and All recapture data were used in the the year of recapture. Stations 3, 4, and 5 two-way analyses of variance, including represented heated (H) areas and stations records of fish that were at large for only 0, 1, 2, 7, and 8 represented unheated a few months. However, by selecting only (U) areas. Movements were categorized as those largemouth bass that had been at (U-U) tagged and recaptured in the large for approximately one complete unheated area, (U-H) tagged in the growing season (N = 69 fish), Joy & Tran- unheated and recaptured in the heated quilli (1979) were able to show that the area, (H-U) tagged in the heated and annual growth of largemouth bass of recaptured in the unheated area, and known sizes was significantly greater in Aug. 1981 Tranquilli ET AL.: Fish Tagging 553 heated than in unheated areas of Lake growing season, about 245 and 194 days Sangchris. They attributed that dif- in the heated and unheated areas, respec- ference in growth rate to the length of the tively. In Lake Sangchris, estimated o^ s.i CT> c: > "7 to ^ Cv] ^ ^ to (U i; t 3 bo "IS eg CM ^ ^ H -H CO ^^ on oo ^ ^- 5i - S O _ * = «> s>: = (J -o 554 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 lengths at ages I through VI, respectively, those which appear in this study for were 138, 278, 380, 434, 462, and 477 largemouth bass are contradictory, both mm in heated areas; 100, 260, 325, 378, studies can be reconciled if one considers 415, and 441 mm in unheated areas; and that seasonal movements in Lake 121, 274, 358,411,444, and 465 mm in all Sangchris are an important factor affect- areas combined (Joy & Tranquilli 1979). ing the results of growth analyses. From these data they concluded that For all three species, the initial length after age I the estimated annual growth and initial weight of the fish had a highly of largemouth bass in Lake Sangchris significant (P < 0.001) effect on the (Fig. 3) was more rapid than in Lake amount of growth achieved by the in- Shelbyville; other Illinois waters in dividual (Table 15) with larger fish grow- general (Bennett & Thompson 1939, ing faster than smaller ones. Gizzard shad Starrett & Fritz 1965, Carlander 1977); were the most important food resource of and waters of the upper Midwest, in- adult largemouth bass and white bass cluding Illinois (Carlander 1977). While (Sule et al. 1981), and larger fish could it may appear that the growth data have consumed the larger gizzard shad presented by Joy & Tranquilli (1979) and forage at any time during the year. 500 n 400- tI3 300- I— CD LAKE SANGCHRIS 200- LAKE SHELBYVILLE ILL. AVERAGE (BENNETT AND THOMPSON 1939, STARRETT AND FRITZ 1965, AND CARLANDER 1977J UPPER MIDWEST AVERAGE 100- (CARLANDER 1977) -1 1 T II III IV VI AGE (YRS) Fig. 3.—Comparison of largemouth bass growth in Lake Sangchris; Lake Shelbyville; other Illinois waters; and waters of the upper Midwest, including Illinois (From Joy & Tranquilli 1979). Aug. 1981 Tranquilli et al. : Fish Tagging 555 whereas, because of size, that food THE EFFECT OF THERMAL resource may have been unavailable to DISCHARGE ON ANNULUS smaller predators. FORMATION BY LARGEMOUTH BASS Significant differences occurred To determine the effect of thermal among years for growth in length and discharge on annulus formation, scale weight of largemouth bass and for growth samples collected from largemouth bass in length of carp (Table 15). For as they were tagged were compared with largemouth bass, the progressive increase scales from the same fish at the time of in mean length from 385 to 420 mm and recapture. Scales were obtained from 50 in mean weight from 946 to 1 ,462 g from bass recaptured with intact tags. The 1974 to 1977 demonstrated that rapid minimum time interval between tagging growth was occurring (Table 16). Growth and recapture was 2 months, and the records were obtained from only a few maximum was 18 months. Twenty-three white bass, but a progn'essive increase in of the 50 recaptures occurred at least 12 length and weight also indicated that months after tagging. Double recaptures they were growing. However, examina- were obtained on four fish, and one was tion of yearly recapture records indicated recaptured three times. that little, if any, carp growth had occurred. Inspection of scales from tagged fish showed that annulus formation occurred Many carp were recaptured that had during the spring in both heated and decreased in length and weight. The unheated areas of Lake Sangchris. An- decrease in length may have been due to' nuli on scales from bass tagged and small errors made in measuring these recaptured in unheated areas were more relatively large and difficult-to-handle distinct than annuli from bass tagged and fish, and decreases in weight may have recaptured in heated areas of the lake. been the result of tagging the fish during When we examined fish scales, we often early spring before females had spawned. made errors in age determination, which In most cases the effect of these factors could only be recognized and corrected would be masked by new growth, but it is by examining another series of scales now apparent that carp in Lake Sangchris from the same fish on a different date. were not growing; so those differences Annuli were not absent on any scales ex- were noticeable. The initial and final amined, but false annuli were common. mean lengths of tagged carp were exactly Thus, investigators analyzing scales of the same (504 mm), and the mean bass from cooling lakes in the Midwest weight of carp at recapture was only 29 g probably would be inclined to greater than at tagging. Population den- underestimate growth and overestimate sity probably was not a factor affecting ages of those fish most affected by the the growth of carp, because the standing thermal effluent. Witt et al. (1970) crop of that species in Lake Sangchris was reported difficulty in reading scales of only 27.0 kg/ha, much lower than the largemouth bass from Thomas Hill average in other midwestern reservoirs Reservoir, a cooling lake in Missouri, ap- (Tranquilli, Joy, & McNurney 1979). parently because the bass moved in and Since carp from Lake Sangchris exhibited out of heated water. Siler & Clugston good growth in a controlled pond en- (1975) found that some bass of all size vironment during the study of tagging ef- groups, subjected to highly elevated fects, it appears that the lack of growth in temperatures (50''C) from a nuclear pro- the cooling lake was due to a shortage of duction reactor in South Carolina, failed food resources. The lack of cavp growth to show an annulus or growth check, may also be related directly to the whereas others had numerous marks that absence of recruitment observed for this resembled annuli. In the latter study, an- species in Lake Sangchris (Tranquilli, nuli were formed in October and Kocher, & McNurney 1981). November, when bass resumed growth 556 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 after being confined to small refuge areas which was calculated to be a standing by the high summer water temperatures. crop of 20.0 kg/ ha. In Lake Sangchris, largemouth bass an- 5.— Analysis of movements between nulus formation occurred in the spring, point of tagging and point of recapture as it does in noncooling lakes in this indicated that there was no relationship region of the Midwest. The annulus ap- between the size of largemouth bass, pears as the result of an increase in carp, or white bass and the distance mov- growth after a slowing or cessation of ed. The grand mean for distances travel- growth during the winter. ed by fish from all areas of the lake com- Dramatic shifts in population density bined was 5,845 m for white bass, 1,635 and movements of radiotagged in- m for largemouth bass, and 1,389 m for dividuals demonstrated that largemouth carp. bass move long distances in Lake 6. — Largemouth bass tagged at sta- Sangchris on a seasonal basis, apparently tions in the discharge and intake areas selecting preferred water temperatures traveled significantly farther than bass (Tranquilli, Dufford, & Larimore 1979 from stations in the middle of the cooling and Tranquilli, Kocher, & McNurney loop. It was suggested that fish from the 1981). The fish were attracted to the intake and discharge areas traveled far- discharge area during winter, and avoid- ther because those habitats represented ed that area during summer. Since it is extreme thermal conditions and the fish practically impossible to determine the at those sites may have been seasonally at- thermal history of individual bass in the tracted to or repelled from thermal gra- population, the scale reading technique dients in the lake. should not be used for age and gjrowth 7. — Movements of largemouth bass, analysis of cooling-lake bass populations carp, and white bass between heated and in this region of the United States. unhealed areas had no effect on their average growth in length or weight, and SUMMARY larger individuals of all three species grew more rapidly than smaller ones. 1 . — A total of 1 , 1 00 recapture records 8. — Composite growth information were obtained from the 5,015 largemouth obtained from recapture records in- bass, carp, and white bass tagged and dicated that largemouth bass and white marked in Lake Sangchris from 1974 to bass growth was rapid, but indicated that 1976. Including multiple recaptures and little, if any, carp growth had occurred. fish recaptured without tags (marks 9. —The effects of thermal discharge only), 38.4 percent of the 2,390 on annulus formation by largemouth bass largemouth bass, 8 percent of the 1,492 in cooling lakes were examined by com- carp, and 5.6 percent of the 1,133 white paring scales taken from the same in- bass were subsequently recovered. dividual at the time of tagging and again 2.— Tag failures were encountered upon recapture. Annulus formation oc- during 2 of the 3 years of study. curred during spring, but false annuli 3. — Largemouth bass populations in were especially common in fish from the Lake Sangchris were estimated with heated area and could not easily be 95-percent confidence by mark-and- distinguished from true annuli. Conse- recapture methods during 1974 and quently, interpretation of annual growth 1975, respectively, to be 11,561 ± 2,952 from marks on scales was not suggested fish _>_150 mm in total length and for cooling-lake bass populations in this 9,444 ± 1,700 fish 2_ 200 mm. From region of the United States. these estimates an average standing crop of 8.8 kg/ha was determined. REFERENCES CITED 4. — In 1976, the number of carp in Barr. a. H. Goodnight. P. Sall, andj. T. Lake Sangchris was estimated with J, J. J. Helwig. 1976. A user's guide to SAS 76. 95-percent confidence to be 13,194 Statistical Analysis System Institute, Inc.. ±2,408 fish ^275 mm in total length. Raleigh. N. C. 329 p. Aug. 1981 Tran^^uilli et al. : Fish Tagging 557 Bennett, G. W.. and D. H. Thompson. 1939. History Survey for Electric Power Research In- Lake management reports. 3. Lincoln Lakes stitute, Palo Alto, CA. 1956. bass tagging. near Lincoln. Illinois. Illinois Natural History KiMSEV, J. B. Largemouth Survey Biological Notes 11. 24 p. California Fish and Game 42(4):337-346. 1957. Largemouth bass tagging at Clear Bryant. H. E., and A. Houser. 1971. Population Lake, Lake County. California. California Fish estimates and growth of largemouth bass in and Game43(2):lll-118. Beaver and Bull Shoals Reservoirs. Pages Lewis, W. M., R. C. Summerfelt, and M. Bender. 349-357 in Gordon E. Hall, ed., Reservoir 1962. Use of an electric shocker in conjunction fisheries and limnology. American Fisheries with the mark-and-recovery technique in mak- Society Special Publication 8. ing estimates of largemouth bass populations. Carlander, K. D. 1955. The standing crop of fish Progressive Fish-Culturist 24(l):41-45. Fisheries Research Board Jour in lakes. Canada Flickinger. 1967. range , and S. Home nal 12(4):543-570. tendency of the largemouth bass (Micropterus . 1977. Handbook of freshwater fishery salmoides). Ecology 48(6):1020-1023. biology. Vol. II. Iowa State University Press, Moody, H. L. 1960. Recaptures of adult large- Ames. 431 p. mouth bass from the St. John's River, Florida. Chadwick, H. K. 1966. Fish marking. Pages 18-40 American Fisheries Society Transactions in A. Calhoun, ed.. Inland fisheries manage- 89(3):295-300. ment. California Department of Fish and Game. QuiNN, T., G. W. EscH, T. C. Hazen, and J. W. Gibbons. 1978. Long range movement and of heated Clugston, J. P. 1973. The effects homing by largemouth bass (Micropterus effluents from a nuclear reactor on species salmoides) in a thermally altered reservoir. diversity, abundance, reproduction, and move- Copeia (3):542-545. ment of fish. Ph.D. Thesis. University of Rawstron, R. B. 1967. Harvest. mortaUty, and Georgia, Athens. movement of selected warmwater fishes in Dell. B. 1968. new fish tag and rapid M. A Folsom Lake, California. California Fish and American Fisheries cartridge-fed applicator. Game 53(l):40-48. Society Transactions 97:57-59. RicKER, W. E. 1958. Handbook of computations for 1949. Results Dequine, J. F., and C. E. Hall, Jr. biological statistics of fish populations. Canada of some tagging studies of the Florida Fisheries Research Board Bulletin 119. 300 p. largemouth bass, MicTopterus salmoides Robson, D. S., andH. A. Regier. I97I. Estimation floridanus (Le Sueur). American Fisheries Socie- of population number and mortality rates. ty Transactions 79:155-166. Pages 131-165 m W.E. Ricker, ed.. Methods for assessment of fish production in fresh waters. I. Dupont, S. p. 1976. The behavior of largemouth B. P. Handbook 3, 2nd ed. Blackwell Scientific bass (Micropterus salmoides) in a reservoir Publications, Oxford. receiving a thermal effluent. M. S. Thesis. University of Georgia, Athens. Siler.J. R., andj. P. Clugston. 1975. Largemouth bass under conditions of extreme thermal stress. Gibbons, W.. and D. H Bennett. 1973. Abun- J. Pages 333-341 in R. H. Stroud and H. Clepper, dance and local movement of largemouth bass management. Sport eds. , Black bass biology and (Micropterus salmoides) in a reservoir receiving Fishing Institute, Washington, D. C. heated effluent from a reactor. Pages 524-527 mD.J. Nelson, ed., Radioecology. 3rd National Smith, S. H. 1954. Method of producing plastic Radioecology Symposium Proceedings, Oak impressions of fish scales without using heat. Ridge. TN. Progressive Fish-Culturist 16(2):75-78. Hasler, a. D., E. S. Gardella, R. M. Horral, Starrett, W. C, and W. Fritz. 1965. A and H. F. Henderson. 1969. Open water orien- biological investigation of the fishes of Lake tation of white bass (Roccus chrysops) as deter- Chautauqua, Illinois. Illinois Natural History mined by ultrasonic tracking methods. Canada Survey Bulletin 29:1-104. Fisheries Research Board Journal 26:2173-2192. Sule, M. J., J. M. McNuRNEY, and D. R. Half- HuLSE, D. and L.F. Miller. 1958. Harvesting of C, field, Jr. 1981. Food habits of some common Wheeler Reservoir, largemouth bass on fishes from heated and unheated areas of Lake of Alabama, 1952-1956. Tennessee Academy Sangchris. Pages 500-519 in R.W. Larimore Science Journal 33:78-83. and J. A. Tranquilli. eds.. The Lake Sangchris an Illinois cooling lake. Il- Jenkins, R. M. 1975. Black bass crops and species study: case history of Survey Bulletin associations in reservoirs. Pages 114-124 in R. linois Natural History 32(4). H. Stroud and H. Clepper, eds., Black bass TRANftuiLLi, J, A., D. W. Dufford, and R, W. Fishing In- biology and management. Sport Larimore. 1979. Activity and preferred D. stitute, Washington, C. temperature of radiotagged largemouth bass in |i)V. T., andJ.A. Tranquilli. 1979. Annual growth Lake Sangchris and Lake Shelbyville. Pages of largemouth bass in Lake Sangchris, Lake 5-1-5 23 in Evaluation of a cooling lake fishery. Shelbyville, and other midwestern waters. Pages Vol. III. Prepared by Illinois Natural History 10-1-10-14 in Evaluation of a cooling lake Survey for Electric Power Research Institute, fishery. Vol. III. Prepared by Illinois Natural Palo Alto, CA. 558 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 for fishes Sangchris determined T. Joy, and J. M. McNurney. 1979, A from Lake by comparison of fish standing crops in Lake tagging studies. Pages 4-1-4-35 in Evaluation of Sangchris and Lake Shelbyville. Pages 21-2-7 a cooling lake fishery. Vol. III. Prepared by Il- in Evaluation of cooling lake fishery. Vol. IIL linois Natural History Survey for Electric Power Prepared by Illinois Natural History Survey for Research Institute, Palo Alto. CA. Electric Research Institute. Palo Alto, Power Witt, A, Jr.. R. S. Campbeu., andj. D. WHrrtEY. CA. 1970. The evaluation of en^ronmental altera- 1981. R. KocHER, and J. M. McNurney. tions by thermal loading and acid pollution in Population dynamics of the Lake Sangchris the cooling reservoir of a steam-electric station. fishery. Pages 413-499 in R.W. Larimore and Missouri Water Resources Research Center. A. Tranquilli, eds.. The Lake Sangchris study: J. University of Missouri. Columbia. 99 p. case history of an Illinois cooling lake. Illinois ZwEiACKER, P. L. 1972. Population dynamics of Natural History Survey Bulletin 32(4). largemouth bass in an 808-hectare Oklahoma 1979. J. M. McNurney, and R. Kocher. reservoir. Ph.D. Thesis. Oklahoma State Growth, movements, and population estimates University, Stillwater. 126 p. Radiotelemetry Observations on the Behavior of Largemouth Bass in a IHeated Reservoir John A. Tranquilli, Donald W. Dufford, R. Weldon Larimore, Richard Kocher, and John M. McNurney ABSTRACT movements of largemouth bass were in- fluenced Small radio transmitters were by temperature changes, whereas surgically implanted in 37 largemouth in Lake Shelbyville directed movements were related to fluctuations in bass from heated, unheated, and transi- water level. tion zones of Lake Sangchris and in 35 bass from unheated Lake Shelbyville to observe their behavior in the wild. Pri- INTRODUCTION mary objectives were to follow long-term Largemouth bass activity was ex- movements and to observe temperature amined by radiotelemetry in Lake selection by individual fish. There were Sangchris, an Illinois cooling lake, and at no significant differences in the daily Lake Shelbyville, a nearby unheated movements of male and female fish from reservoir, to make a comparative evalua- either lake. The average daily movement tion of bass behavior. The comparative of bass from the heated zone of Lake study at Lake Shelbyville became Sangchris (248.3 m) was significantly necessary because a relatively new greater than that of fish from the technology was being used which allowed unheated zone (126.1 m), the transition more intensive investigation than had zone (91.1 m), or Lake Shelbyville (116.3 previously been possible. The objectives m). The final preferred temperatures of the study were to compare activity and selected by radio -tagged fish from the temperature selection of fish in the two heated zone of Lake Sangchris during Ju- reservoirs and thereby determine the ef- ly and August (30.5"'C) were significantly fects of thermal discharge on fish greater than that of fish from any other behavior in the cooling lake. The study area. Temperatures selected by fish radiotelemetry studies conducted at Lake from the unheated (29.1°C) and transi- Shelbyville were funded by the Electric tion (28.2°C) zones of Lake Sangchris Power Research Institute, Palo Alto, were not statistically different from each California. other but were significantly higher than tliose selected by fish from Lake METHODS Shelbyville (26. PC). In Lake Sangchris, Radio transmitters (50 MHz) developed by William Cochran, a wildlife Dr. John A. Tranquilli is an Associate Aquatic specialist for the Illinois Natural History Biologist in the Section of Aquatic Biology, Illinois Survey, and marketed by AVM Instru- Natural History Survey; Donald W. Dufford is with ment Co., Champaign, Illinois, were used the Illinois Department of Conservation. in this study. The radio tags consisted of a Charleston, Illinois: Dr R, Weldon Larimore is an miniature radio crystal, a battery, and a Aquatic Biologist in the Section of Aquatic Biology, loop antenna; the total package resembl- Illinois Natural History Survey; Richard Kocher is ed a small padlock 55 x 25 x 10 mm that with the Wabash Production Credit Association, weighed_15-20 g. Robinson. Illinois; and John M. McNurney is with R. W. Beck and Company, Denver, Colorado. Wild largemouth bass were captured from Lake Sangchris and Lake This chapter submitted in Feb. 1980. Shelbyville by AC electrofishing and 559 560 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Fifty-MHz radio trans- milter used to study the behavior of largemouth bass in Lake Sangchris. The transmitters were encased in a plastic material before they were implanted in fish. transported to a field laboratory. The itiated in September rather than in spring bass were anesthetized with MS-222 and to observe fish behavior in relation to quinaldine, and radio tags were inserted thermal discharge during winter. For into the body cavity through a 40-mm comparative purposes, the Lake incision in the ventrolateral musculature Sangchris data were analyzed according of each fish. The incision was closed with to the particular study area where radio- five or six stitches of nylon thread. A tagged fish were originally released: the numbered Floy Anchor tag (Model FD68- heated, transition, and unheated zones. B), with instructions to notify the Natural Bass tagged throughout Lake Shelbyville History Survey by telephone, was inserted were considered as being from one study i behind the dorsal fin of each radio-tagged area and having behavior characteristic bass. The fish were released at their of fish in an unheated reservoir (Fig. 1). places of capture following a very short In Lake Shelbyville, most fish were releas- surgical recovery period (usually 1-2 ed during the spring, but a few were hours), and generally were returned to released as late as mid-July. the lake within 24 hours after their cap- In both lakes, attempts were made to ture. We found it best to return the tag- locate each radio-tagged fish three times ged fish to their natural environment as per week. Tracking was conducted by soon as possible to minimize the effects of boat, and locations were determined by captivity on their behavior. Some sham triangulation of radio signals with a operations were conducted and it was directional yagi antenna. The depth at observed that the incisions of fish held in which each fish was located was estimated laboratory captivity became infected, by comparing the distance over which the whereas incisions of radio-tagged fish signal could be heard with known signal recaptured from the lake did not. An at- attenuation for known depths. Fish loca- tempt was made to tag equal numbers of tions were plotted on detailed maps. In male and female fish of the same approx- Lake Sangchris, water temperatures were imate size (1 kg) in each study area. not taken at each fish location during Radiotelemetry studies of large- 1974, but in 1975 and 1976 they were j mouth bass were conducted in Lake recorded for the depth at which the fish was found. In Lake Shelbyville, for each Sangchris and Lake Shelbyville over a | 4-year period (1974-1977). During 1974 fish location, a water temperature was and 1975, equal numbers of fish were taken at the surface in 1975 and 1976, radio tagged during early spring in and at the depth of the fish during 1977. heated (stations 3, 4, and 5) and Movements were measured on a unhealed (stations 1, 2, and 7) zones of large map as straight line (by water) Lake Sangchris (Fig. 1). In 1976, all distances between fish locations. As used radio- tagged fish in Lake Sangchris were in the tables and text, total travel was released during the first week of calculated for each fish as the sum of September in a transition zone, a study distances between consecutive locations, area representing the outermost limit of the maximum range was defined as the the thermal gradient between the dam total distance between the two most dis- and the northern part of the eastern arm. tant observations, and the range from Studies in the transition zone were in- release point was the distance between Aug. 1981 Tranquilu et al. : Radiotelemetry Observations on Bass Behavior 561 the original capture point (release point) the number of days in the study period. and the most distant observation. As a result of wide variation in study Average daily movement was calculated periods for individual fish, the average by dividing the total distance traveled by daily movement was selected as the best o to to T3 OCS O I > « 0) CS _l T>C cd CO CO CO 562 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Surgical implantation of a radio transmitter in a largemouth bass. measure for comparing fish activity be- covariable for this analysis. When signifi- tween study areas. The final mean prefer- cant differences were found, a Duncan red temperature (°C) was determined for Multiple Range Test was used to compare fish observed six or more times duringju- the means. ly and August. Data were analyzed using the RESULTS AND DISCUSSION Statistical Analysis System (SAS) GLM procedure (Barr et al. 1976) on an IBM Observations on the movements of 360/75 computer at the University of Il- radio-tagged largemouth bass from linois Urbana campus. Analysis of heated, unheated, and transition zones of variance was used to compare the average Lake Sangchris, and from unheated Lake daily movement of the radio-tagged fish; Shelbyville are summarized in Tables 1-4, study area (heated, unheated, and transi- respectively. In Lake Sangchris, 37 tion zones of Lake Sangchris and Lake largemouth bass were studied: 13 from Shelbyville) and sex were tested as main the heated zone, 13 from the unheated effects. Initial length of the fish was used zone, and 11 from the transition zone. as a covariable. Analysis of variance was Thirty-five bass were studied in Lake also used to compare the final preferred Shelbyville. The average weight of the temperature selected by largemouth bass radio-tagged fish from the heated, released in different study areas. Initial unheated, and transition zones of Lake length of the fish was again used as a Sangchris and from Lake Shelbyville were A largemouth bass that has had a temperature- sensitive radio transmitter im- planted in its body. Note the external thermistor. Aug. 1981 Tranquilli et al. : Radiotelemetry Observations on Bass Behavior 563 1.32, 1.36, 0.98, and 1.20 kg, respective- studied; in the transition zone, 4 females ly. In each of the heated and unheated and 7 males were studied; and in zones, 7 female and 6 male fish were unheated Lake Shelbyville, 20 females, J3 E > o E (0 E E ^« I- -^ en ' 564 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 12 males, and 3 fish of unknown sex were radio-tagged bass from the heated, studied. unhealed, and transition zones of Lake The average study period for each Sangchris was 152, 143, and 311 days, cO) CO OT — Aug. 1981 Tranquilli et al. : Radiotelemetry Observations on Bass Behavior 565 respectively. The longer study period for battery life of the radio tags at low winter fish tagged during September in the tran- temperatures. In Lake Shelbyville, the sition zone probably was due to greater average study period for each fish was 98 Xi CO CO CO 3 O E C3) c E o E o >. E g E E w3 * JO 566 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 days. The shorter average study period in caught and removed from the lake or that Lake Shelbyville was partially accounted died after being captured and released by for by 12 radio-tagged fish that were fishermen. Xl Aug. 1981 Tranquilli ET AL.: Radiotelemetry Observations on Bass Behavior 567 Largemouth bass from the unhealed movement was calculated for each fish zone of Lake Sangchris showed the and was found to be the most comparable smallest maximum range (average 3.54 measure of fish activity among the dif- km). Fish in Lake Shelbyville and those ferent study areas. from the transition zone were in- The average daily movements of termediate (4.15 km), while fish from the largemouth bass might be affected by the heated zone showed the largest maximum fish's sex, size (initial length), and time of range (7.03 km). A pattern similar to that the year. May was selected to represent for maximum range was found among the spawning season and October to the study areas for the range from point represent the autumn activity period. A of release. In Par Pond, a cooling lake for two-way analysis of variance, incor- a nuclear reactor in South Carolina, porating these variables, was used to similar observations were made by Du- compare the activity of radio-tagged bass pont (1976) who reported movements as from the three different thermal zones of large as 6.5 km for largemouth bass Lake Sangchris and from Lake tagged in heated areas while bass from Shelbyville (Table 5). There was no unhealed areas tended to move in a more significant difference (0.05 level) in the localized area near their release site. Fish average daily movement of male and from the heated area of Lake Sangchris female largemouth bass at any time of the may have shown greater range because year. Average daily movements of male they were most influenced by the thermal (N= 31)andfemale(N= 38)largemouthbass discharge and traveled farther because of were 145.5 andl33.7 km, respectively. Forour seasonal attraction and/ or avoidance of it. fish, there was no interaction between sex and Total distance traveled by bass from the study area at any time of the year. The size dif- heated and transition zones of Lake ferences among the fish had no effect on Sangchris averaged 30.03 and 27.68 km, their average daily movements; however, respectively, while total travel by fish the fish studied were all mature adults of from the unhealed zone in Lake the same general size. An ultrasonic Sangchris and from Lake Shelbyville was telemetry study of largemouth bass much lower at 13.29 and 11.29 km, movements using fish of different sizes in respectively. Although these measure- Lake Keowee, a South Carolina cooling ments—maximum range, range from lake, revealed that age, length, and release point, and total travel — are weight were positively correlated with the all general indices of fish movement, the size of the home range (Chappell 1974). duration of the study period for in- There was a significant difference (P dividual fish undoubtedly affected these < 0.05) in fish activity between study measures. To avoid the influence of time areas for the entire year, but not for each fish was followed, an average daily movements by fish in different areas dur- Table 5. —Analysis of variance comparing average daily movement of radio-tagged largemouth bass released in different areas of Lake Sangchris and Lake Shelbyville during May. October, and the entire year. Areas of release were heated, unheated, and transition zones of Lake Sangchris and unheatect Lake Shelbyville. Initial length was used as a covariable^ in the analysis. Average Daily Movement (m) Source of Variation 568 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 6. — Duncan's multiple-range test connparing average daily movement of radio-tagged largemouth bass released in the heated (HT), unheated (UH), and transition (TR) zones of Lake Sangchris and unheated Lake Shelbyville (SH). Means with the same group letter are not significantly different at the 0.05 level. Aug. 1981 Tranquilli et al.: Radiotelemetry Observations on Bass Behavior 569 •>*•— to on CT)N.-i^.-«onMon i— Oi CO on i£) •—! 400 LAKE SANGCHRIS (HEATED ZONE) 300 200- 100- LAKE SANGCHRIS (TRANSITION ZONE) 300- 200- Fig. 2 —Average daily > o movement of radio-tagged largemouth bass from fieated, SANGCHRIS transition, and unfieated (UNHEATED ZONE) zones of Lake Sangchris and < 300- from Lake Sfielbyviiie from < 200- 1974 to 1977. LAKE SHELBYVILLE 300- 200 100- s MONTH Study area (Table 8). Throughout the selected by bass from Lake Shelby%ille. year, preferred temperatures of Largemouth bass from the cooling lake, largemouth bass from all areas in Lake particularly the fish released in the transi- Sangchris were higher than those from tion zone during September 1976, did not Lake Shelbyville (Fig. 3). From April select the warmest water temperatures through September, temperatures available in Lake Sangchris during selected by bass from the heated zone winter. Clugston (1973), using averaged 2.0°C warmer than temperature-sensing transmitters in Par temperatures selected by bass from the Pond, also found that largemouth bass transition zone of Lake Sangchris. During did not utilize the warmest water the same 6-month period, bass from the available during the winter months. transition zone selected temperatures that For each study area, a final prefer- averaged only O.PC warmer than those red temperature was determined for fish selected by bass from the unheated zone. that had been observed 6 or more times That small difference probably would during July and August. An analysis of have been greater if bass had not been variance was used to compare the final released in the transition zone during preferred temperatures selected by fish September 1976, when temperatures from each study area, using initial length were lower than normal because there of the fish as a covariable (Table 9). A had been a 6-week power plant shut highly significant difference (P<0 001) down. From April to September, bass was found among study areas for the final from the unheated zone of Lake preferred temperatures selected. The Sangchris selected water temperatures length of the fish had no significant effect that averaged 2.0°C warmer than those on the final preferred temperatures Aug. 1981 Tranquilli et al.: Radiotelemetry Observations on Bass Behavior 571 selected by radio-tagged fish, but, as red temperatures of radio- tagged bass mentioned previously, the fish used were from the heated zone of Lake Sangchris all adults of similar size. The final prefer- (30.5°C) were significantly (P<0.05) greater than that of fish from any other study area (Table 10). The final prefer- red temperatures of fish from the unheated (29.1°C) and transition (28.2''C) zones were not significantly dif- ferent from each other, but were significantly higher than temperatures selected by fish from Lake Shelbyville (26.5»C). The abnormally low final preferred temperature of bass from Lake Shelbyville resulted, in part, because warmer temperatures were not always available. In Par Pond, Dupont (1976) found that largemouth bass tagged with ultrasonic temperature-senstitive tags selected temperatures of 28.8°-30.3°C in heated areas and 26.3° 27.7 °C in unheated areas. Dupont also found, as we did, that mean selected temperatures of both groups of bass were significantly dif- ferent from each other during July and August. The outward migration of radio-tag- "' m M — ged bass from the heated zone of Lake cJc^-— — ~-' cn "^ '^ Sangchris during the summer of 1974 and 00 „ =^ ^ ^ =-1 Z^l CM 1975 was attributed to avoidance of elevated temperatures. The final prefer- X C — C-) CI u'-. 'X iT. red temperatures selected by those bass -^ .-: -^ ^ -^ ^ C :£ were generally unavailable in the middle arm of the cooling lake from the X cr O — it; cr r* cvj discharge area to the junction of the mid- — ti — r^ — '^ " ' tr. t~- '^ c^j ' dle arm with the control arm (Fig. 1). C-J CJ However, even after bass from the heated zone of the cooling lake had traveled to ' regions, they still selected _ r- ^ 3-. ^ '^ ^ unheated warmer temperatures than bass from unheated zones. The comparison of — i^ in temperature preferences and activity pat- t£ C 0-, -^ r- C ' terns of largemouth bass from three ther- mal zones of Lake Sangchris and from Lake Shelbyville suggested that perhaps — C-J ^- 1£ _ _ acclimatization to higher temperatures may have occurred in the cooling lake through genetic selection for tolerance of higher temperatures. The genetic variability of largemouth bass popula- tions in Lake Sangchris and Lake Shelbyville was studied by Childers a; = o (1979), who found a significant dif- •— ^ -^ ference in the frequency of alleles at the 572 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 32 - 30 28 26 - 24 22 - 20 O ^ IB Fig. 3. — Preferred temper- LlJ atures selected by radio- !£ tagged largemouth bass from < heated, transition, and u; 14 unhealed zones of Lake Sangchris and Lake UJ 12 Shelbyville (1975-1977). 10 8 SANGCHRIS (HEATED ZONE) 6 SANGCHRIS (UNHEATEDZONE) SANGCHRIS (TRANSITION ZONE) SHELBYVILLE AMJJASOND MONTH Table 9. —Analysis of variance for summer preferred temperatures ("C) selected by radio- tagged largemouth bass released in heated, unhealed, and transition zones of Lake Sangchris and in unhealed Lake Shelbyville. Initial length was used as a convariable^ in the analysis. Summer Preferred Temperature Aug. 1981 Tranquilli et al. : Radiotelemetry Observations on Bass Behavior 573 the fish (Brett 1956). Comparison of general agreement with the preferred literature on preferred temperature for range of temperatures reported in the largemouth bass can be misleading literature for this species. The final because various investigators have ex- preferred temperature of largemouth pressed the preferendum as a modal bass from Lake Shelbyville (26.5''C) was temperature, others as a mean selected slightly lower, probably because, as men- temperature. In addition, studies for tioned earlier, higher temperatures were temperature preference have been con- not always available in July and August. ducted in both laboratory and field en- Seasonal movements of largemouth vironments, using fish of different sizes, bass in Lake Sangchris are discussed in at different times of the year, in different relation to the study area (heated, geographic locations, and with different unheated, and transition) and year in genetic backgrounds. which they were originally tagged and Laboratory studies have generally released. The behavioral movements of shovi'n higher temperature preferenda for individual fish relative to the thermal largemouth bass than have field studies. outfall in the cooling lake are shown in 4-13. Ferguson (1958) first noted the lack of Fig. agreement and attributed it to the dif- Five of the six fish tagged and releas- ferences in size and age of the fish ed in the thermal zone during the spring studied; laboratory experiments were of 1974 migrated away from the thermal conducted with young fish and field outfall (Fig. 4) and arrived in cooler studies with older fish. In laboratory refuge areas by 1 August. These five fish studies, Ferguson (1958) cited a preferred each made directed movements of at least temperature of 30''-32»C for largemouth 7.24 km (4.5 miles). By midsummer, four bass, while Strawn (1961) found that of these fish (No. 1,2,3, and 4) had con- largemouth bass grew best at about 30°C. gregated at the cooling water intake of Dendy (1948) determined the preferred the power plant. Only one of the six fish temperature of largemouth bass in Norris released in the heated area (No. 6) re- Reservoir, Tennessee, to be 26.6»-27.7»C. mained in the southern portion of the Coutant (1974) found,' via acoustic discharge arm during midsummer. When telemetry, that largemouth bass had a water temperatures were highest, this fish final temperature preferendum of about was found in the deepest, coolest water ^7°C in small Tennessee lakes. In Wis- available in that region of the lake. Dur- consin, Neill & Magnuson (1974) found ing October and November when water the median body temperature of large- temperatures in the lake began to cool mouth bass during the afternoon in a naturally, two of the five remaining fish thermal outfall at Lake Monona to be (No. 3 and No. 5) reversed direction and 29.7°C which agreed well with the mid- migrated back toward the thermal out- point of the preferred temperature fall. (29.1°C) observed in their laboratory for The movements of the six fish releas- this species. By concentrating their ed in unheated areas during spring 1974 sampling effort in the area of thermal were relatively small in comparison to discharge at Lake Sangchris, Smith & those observed for fishes from the heated McNurney (1981) found a final preferred area and were not generally directed away temperature for largemouth bass of from the thermal discharge during mid- 32.4"C, which was very near the highest summer (Fig. 5). Of the three remaining preferred temperature previously fish, two (No. 9 and No. 10) made sub- reported in the literature. stantial movements toward the thermal discharge during October and The final preferred temperatures November, and the third fish (No. 8) I selected by radio-tagged largemouth bass moved in that direction in December. from the heated, unheated, and transi- tion zones of Lake Sangchris, 30.5°, Of the seven fish tagged and released 29. P, and 28.2''C, respectively, were in within the southern end of the discharge 574 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 ("w"">i!t) invjino TvwMaHi woaj aONVisia .*• M M ... O o o !2 « CO > a> > » ? (D m D T3 CO o ra c to 0) Si >• 5CD -— o> — iS g "- CO CO p il3 CO O O)S5, E ra o> U J? =6 X Q) CO .c CO c t: O 3 '*- o o E ™ £ CO 0) c .C Q) *" CO O 0) c Q- O £ - to (o aj 1™ E « S >- O CT, CO '- OC ^ CO O 2 I CO . CO row 5 I I SE — O 5jCD (s»iiui| Tivjino nvKMaHi wohj aanvisia ^ Aug. 1981 Tranquilli et al. : Radiotelemetry Observations on Bass Behavior 575 (sjaisoioiTJt) TTVJJJIO TVWHaHX WOHJ aONVlSIQ P3 N .-H tn t I ' • > I I III till r " 1 T r r ^' — T-< O O) 00 t- (O lO 576 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 1975 RADIO-TAGGED FISH IN HEATED AREA Fig. 6. —Radiotelemetry observations on movements in relation to the thermal outfall of three largemouth bass tagged and released in heated areas of Lake Sangchris (No. 1-3) during spring 1975. The shaded area represents that portion of the discharge arm most highly influenced by elevated water temperatures. 1975 RADIO-TAGGED FISH IN HEATED AREA - 12 r- 19 IS 11 - 17 10 - _ 16 - 15 9 I _ 14 E -I 13 u. . 12 O 7 - 11 - 10 i ^ i 5- Fig. 7. — Radiotelemetry observations on movements in relation to the thermal outfall of four largemouth bass tagged and released in heated areas of Lake Sangchris (No. 4-7) during spring 1975. The shaded area represents that portion of the discharge arm most highly influenced by elevated water temperatures. Aug. 1981 Tranquilli ET AL. : Radiotelemetry Observations on Bass Behavior 577 arm during the spring of 1975 (Fig. 6 and out of the heated zone during midsum- 7), four (No. 2,3,4, and 7) migrated mer of 1974 and 1975 was apparently beyond the 5.6 km mark (mile 3.5) to caused by elevated water temperatures. reach the control arm and another (No. The directed movements in Lake 1) traveled between the intake and Sangchris could be characterized as discharge arm several times. Within a migrations between relatively small 15-day period, fish No. 5 was tracked seasonal activity centers determined by from its point of release, near the thermal behavioral thermoregulation. In Lake outfall, to the junction of the discharge Shelbyville, directed movements were and control arms and back to its point of related to changing water levels during release. Throughout the spring, summer, 1975 and 1977, In 1976, when water and fall, fish No. 6 remained mostly levels were stable at Lake Shelbyville, within the southern portion of the directed movements by several fish at a discharge arm. During midsummer this time were not observed (D. W. Dufford, fish took refuge in an extensive stand of unpublished data). American lotus in a cove where Radio-tagged bass in Lake Sangchris temperatures were 5°-6°C cooler than in and Lake Shelbyville were observed most adjacent midlake areas. often in relatively shallow water (1-4 m) The movements of the seven fish along the shoreline. In Lake Sangchris, released in the intake arm during the bass from the heated zone could have spring of 1975 are shown in Fig. 8 and 9. avoided elevated temperatures by moving Fish No. 9,1011, and 14 moved relatively relatively small vertical distances to small distances from the point of tag- deeper midlake areas where sufficient ging and release. In late June, fish No. 12, dissolved oxygen usually was available. released near the intake canal, moved However, the majority of the bass in Lake toward the thermal outfall, but took Sangchris traveled relatively long refuge near the dam during midsummer. (several km) horizontal distances to avoid Fish No. 13 remained in the southern elevated temperatures but remained in portion of the intake arm all summer but relatively shallow water along the during the fall it moved approximately shoreline. Radio-tagged bass in Lake 6.4 km (4 mUes) in the direction of the ther- Shelbyville also remained in relatively mal outfall. shallow water along the shoreline, rather Nine of the 1 1 fish released in the than move to deeper cooler areas during transition zone of Lake Sangchris during the summer seasons. In both lakes, bass September 1976 were attracted to the traveled across open water to get from discharge arm during winter one shoreline to the other, particularly (Fig. 10, 11, 12, and 13). However, those when the fish were moving between areas. fish did not seek the warmest This behavior is in contrast to the obser- temperatures (those available in the vations of Parker & Hasler (1959) and discharge canal), but instead con- Zweiacker (1972) who reported that bass gregated in the heated middle arm near avoided crossing open water. Although its junction with the unhealed east arm Lewis & Flickinger (1967), Hasler & where intermediate temperatures prevail- Wisby (1958), and others found that bass I ed. sought deeper water during winter, Relatively small seasonal activity radio-tagged fish in Lake Sangchris and centers were established by most bass in Lake Shelbyville remained in water of ap- Lake Sangchris. Major movements occur- proximately the same depth (1-4 m) red over a relatively short time spjm (a few throughout the year. hours to a few days). In Lake Sangchris, In Lake Shelbyville, none of the six the movements almost always were fish studied during 1975 was recovered oriented to the thermal gradient and but 13 of the 15 fish with radios during temperature was consistently indicated as 1976 were captured by fishermen. Two the primary factor affecting movement. fish were recaptured three times and two Migration by 10 of 13 radio-tagged bass fish were recaptured twice, making a 1 578 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 1975 RADIO-TAGGED FISH IN UNHEATED AREA 1 T -I 1 1 AUG OCT NOV DEC Fig. 8. — Radiotelemetry observations on movements in relation to the thermal outfall of four largemouth bass tagged and released in unheated areas of Lake Sangchris (No. 8-1 ) during spring 1975, The shaded area represents that portion of the discharge arm most highly influenced by elevated water temperatures. total of 19 recaptures by fishermen dur- of the 19 recaptured fish v^ere released in ing 1976. Fishermen moved five of the the area where captured; seven remained recaptured fish considerable distances in the immediate area, and one moved at before releasing them. None of those fish least 3.425 km within 20 hours. The other showed any indication of homing, or six fish recaptured by fishermen were returning to the point of capture. Eight removed from the lake. Three of the 13 1975 RADIO.TAGGED FISH IN UNHEATED AREA 19 - IB 14 - 17 - 16 - 15 - 14 13 13 12 Fig. 9. —Radiotelemetry observations on movements in relation to the thermal outfall ot three largemouth bass tagged and released In unheated areas of Lake Sangchris (No. 12-14) during spring 1975. The shaded area represents that portion of the discharge arm most highly influenced by elevated water temperatures. Aug. 1981 Tranquilli et al.: Radiotelemetry Observations on Bass Behavior 579 (siaiaoioipi) TlVjtmO TVWHaHX WOHJ a^Nvisia in V « c^ O) Xt-som-vrtN — s I I I I I I I I I I I I I I— ..j,., I I I > 580 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 (siaiauioirn) TlVJXIlO TVWHaHl WOHi aONVlSIO I I ' I L. -L_J I I L. 2 > m (D CO O CO C -1 in •O <3> S" w a) £ 5 o 5 1=^ ° ra CO £ i « £: •^ 0) CO £ Q. C CD £•- c = O CO <" ™ o £ a> CD CO €^.I ii a sz fl> o •S o> CO O c Of I J<: CO CO Q. ::-' E 1 CO S (sajim) TTVJino IVWHSHl WOMi aSNVjsia Aug. 1981 Tranquilli et al. : Radiotelemetry Observations on Bass Behavior 581 (sja)3uion:() TlVJinO TVWMaHi WOHi aDNVlSIQ OS QO r- O <1> I 1—1 I I I I l__l L J L J I I L 5 0) E^ §^ O) m o at ^es> ^ c >, s,^ O) en <0 O Se £<« oi" 4) £ So = ° SB 3 O- *- _ (0 (0 ^ £ <» 1 £ •^ Q. O 2 C to g <1> 0) "O ir 0) .£ oj B) '^ S ^ i- » --^ CO O) X3 I O N. >• 6 E.M ®^ B o • -n — >- "5 -S I (0 0,0 - Eras I I (sanui) nivjjiio TvwaaHX wohj aonvisia 582 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 (uaj»uion!|) TlViinO TVlTOaHX WOHJ aoNvisia C T3 O ' I I I I I I _l l__l l__l I ' ' ' -a> ;^c ^?CO .c CO 1- n CO .c a) 3 ? pO CO o£ og S5 ° » E « ® £ *- ; CO 0) o •- *" c oCO SS CO " > t OE^O) oC= —CO S = > ^ €° «S E CO oj •;: e- Of w ra I 5£ C2JSI n 5 (»nui) Tivjiao TVWHaHi wohj aoNvisia Aug. 1981 Tranquilli et al.: Radiotelemetry Observations on Bass Behavior 583 bass caught and released by fishermen Lake Sangchris (248.3 m) was significant- died within 3 weeks, possibly as a result of ly (P<0.05) greater than that of fish being hooked. In 1977, four of 14 radio- from the unhealed zone (126.1 m), the tagged fish were caught by fishermen. transition zone (91.1 m), or from Lake One of the four fish captured in 1977 was Shelbyville (116.3 m). removed from the lake and two others 3. —The final preferred temperature died, 11 and 13 days after being released selected by radio- tagged fish from the the fishermen. The fourth fish was by heated zone during July and August moved across the lake from its place of (30.5°C) was sigfnificantly greater (P < capture but had returned to it within 17 0.05) than that of fish from any other days. The large number of radio-tagged study area. Fish from the unhealed bass recaptured by fishermen (29. PC) and transition (28.2°C) zones of that the radio tags did demonstrated Lake Sangchris selected temperatures not prevent the fish from feeding. that were not different from each other, higher than Only seven of the 37 radio-tagged but which were significantly fish Lake bass studied in Lake Sangchris those selected by from (1974-1977)were captured by fishermen; Shelbyville (26. 1°C). three were caught after the radios had 4. — Comparison of temperature signals. One fish stopped transmitting preferences and activity patterns of bass found dead with an active radio tag was from three thermal zones of Lake after being from unknown causes 42 days Sangchris and from Lake Shelbyville sug- During elec- tagged and released. gested that acclimatization to higher Sang- trofishing population surveys at Lake temperatures may have occurred in the chris, four radio-tagged fish were recap- cooling lake through genetic selection for radios function- tured and released with tolerance to higher temperatures. ing and seven others were recovered with 5. — In Lake Sangchris, movements inactive radios. by radio- tagged fish were oriented to the Of the 37 bass with implanted radios thermal gradient, whereas in Lake in Lake Sangchris, 16 were examined ex- Shelbyville directed movements were ternally 12 dissected and examined and related to changing water levels. internally. Those examinations indicated that the external wounds were completely REFERENCES CITED healed in approximately 4 weeks. Ap- P. Sall, Barr, a. J., J. H. Goodnight, J. and parently, feeding and growth of radio- user's to 76. J. T. Helwig. 1976. A guide SAS tagged bass were normal, and several Statistical Analysis System Institute, Inc. females recaptured during early spring Raleigh, NC. 329 p. Brett. R. 1956. Some principles of the thermal had highly developed ovaries indicating J, requirements of fishes. Quarterly Review of that reproduction was still possible. From Biology 31(2):75-87. these observations, it is believed the inter- of bass Chappell, J. A. 1974. Response largemouth nally implanted radio transmitters had to thermal effluent from Oconee Nuclear Power Thesis, Clemson University. Clem- little effect on the behavior of the fish, Plant. M.S. son, SC. 39 especially after the incision had healed, p. Chiu)ers, W. F. 1979. The effect of a heated ef- and that the observed behavior of fluent on the frequency of two alleles at the largemouth bass in this long-term study Mdh-B locus in largemouth bass, Mtcropterus was normal and highly characteristic of salmoides. Pages 13-1-13-18 in Evaluation of a cooling lake fishery. Vol. Ill, Illinois Natural the species. History Survey final report to Electric Power SUMMARY Research Institute, Palo Alto. CA. heated ef- Clugston. J, P. 1973. The effects of dif- 1.— There were no significant fluents from a nuclear reactor on species diversi- ferences in the daily movements of male ty, abundance, reproduction, and movement of and female fish. fish. Ph.D. Thesis, University of Georgia, Athens. 104 p. 2 . — The average daily movement of Coutant, C. C. 1974. Temperature selection by largemouth bass from the heated zone of fish — a factor in power plant inpact assess- 584 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 I ments in Symposium on the physical and fluent from a power plant at Lake Monona, biological effects on the environment of cooling Wisconsin. American Fisheries Society Transac- I systems and thermal discharges at nuclear power tions 103 (4):663-710. stations. Oslo, Norway. 25 p. Parker, R. A. , and A. D. Hasler. 1959. Movements distribution displaced centrarchids. 1959 Dendy, J. S. 1948. Predicting depth of of some Copeia fish in three TVA storage-type reservoirs. (1):11-18. American Fisheries Society Transactions Petersen. D. C. 1975. Ultrasonic tracking of three 75:65-71. species of black basses, Microptenis spp.. in DupoNT, S. p. 1976. The behavior of large- Center Hill Reservoir, Tennessee. M.S. Thesis, mouth bass (Microptenis salmoides) in a reser- Tennessee Technological University, Cooksville. voir receiving a heated effluent. M.S. Thesis, 129 p. D. C. 1974. Movement and home range of University of Georgia, Athens. 60 p. Smith, I Ferguson, R. G. 1958. The preferred temperature largemouth bass (Micropterus salmoides) tag- of fish and their midsummer distribution in ged with ultrasonic transmitters. M. S. Thesis. temperate lakes and streams. Canada Fisheries Clemson University, Clemson. SC. 39 p. 1981. Behav- Research Board Journal 15(4):607-624. Smith, V.J., and J. M. McNvrney. an- ioral thermoregulation of largemouth bass and Fry, F. E. J. 1947. Effects of the environment on imal activity. University of Toronto Studies, carp in an Illinois cooling lake. Pages 585-593 Biological Series No. 55. 62 p. in R. W. Larimore and J. A. Tranquilli. eds.. Hasler, a. D., and W.J. Wisby. 1958. The return The Lake Sangchris study: case history of an Il- of displaced largemouth bass and green sunfish linois cooling lake. Illinois Natural History to a "home" area. Ecology 39(2):289-293. Survey Bulletin 32(4). Lewis. W. M.,and S. Flickinger. 1967. Home Strawn, K. 1961. Growth of largemouth bass fry at range tendency of the largemouth bass various temperatures. American Fisheries Socie- (MicTOpteTus salmoides). Ecology ty Transactions 90(3):334-335. 48(6):1020-1023. Warden, R. L., and W.J. Lorio. 1975. Movements D. of largemouth bass (Micropterus salmoides) in LoRio, W. J., R. L. Warden, Jr., and T. Thornhill. 1973. The effects of water manage- impounded waters as determined by underwater ment practices on the movement of largemouth telemetry. American Fisheries Society Transac- bass. Water Resources Research Institute, tions 104(4):696-702. Mississippi State University. 46 p. ZwEiACKER, P. L. 1972. Population dynamics of 1974. Dis- largemouth bass in an 808-hectare Oklahoma Neill, W. H., and J. J. Magnuson. tributional ecology and behavioral thermo- reservoir. Ph.D. Thesis. Oklahoma State regulation of fishes in relation to heated ef- University, Stillwater. 126 p. Behavioral Thermoregulation of Largemouth Bass and Carp In an Illinois Cooling Lake Valerie J. Smith and John IVI. l\/lcNurney ABSTRACT water temperature differences as small as (Bull and some are able to The preferred temperatures of 0.03''C 1936), distinguish between increasing and largemouth bass and carp were determin- decreasing temperature (Bardach & ed in vivo during the summer months at Bjorklund 1957). Characteristic thermal Lake Sangchris, a power plant cooling preferenda have also been identified for lake in central Illinois. Their preferred temperatures were inferred from many species. Such preferences vary for depending on acclimation measurements of the internal body each species temperature (Ferguson 1958), season of temperatures of fish captured in areas the year (Zahn 1963 and Fry 1967), and where a wide range of water temperatures of the fish (Fry 1937). was available. Most of the samples were age taken in the heated arm of the lake, Water temperature ranges and gra- where water temperatures exceeded the dients in cooling lakes are often quite dif- previously reported preferred ferent from those in lakes that do not temperatures for largemouth bass and receive a thermal discharge. Atypically carp. The preferred temperatures deter- high temperatures may be encountered in mined were approximately 32.3°C for cooling lakes, especially during the sum- largemouth bass and 31.8°C for carp. mer when normal vertical thermal These estimates were -very near the stratification is often disrupted and highest preferred temperatures reported horizontal thermal gradients may be en- for these species in a variety of laboratory countered. In this study, some aspects of and field investigations. the thermoregulatory behavior of largemouth bass {Micropterus salmoides) and carp (Cyprimis carpio) in Lake INTRODUCTION Sangchris, a cooling reservoir in central Fishes, except for some large, fast- Illinois, were examined during the sum- swimming marine species (Carey 1973), mer of 1975. Efforts to determine the are incapable of physiological control of final preferred temperatures of these body temperature. Many species, species were concentrated in that portion however, accomplish a limited amount of of the reservoir most affected by the ther- temperature regulation through mal effluent. behavioral responses that position them in water of a particular temperature. STUDY AREA AND METHODS Such behavioral thermoregulation re- Lake Sangchris, an 876-ha (2,165-_ quires that the fish be capable of ac- acre) reservoir, provides condenser cool- curately detecting water temperature and ing water for Commonwealth Edison of responding appropriately to it with Company's Kincaid Generating Station. respect to a reference, or preferred, The reservoir has three arms. Each arm is temperature. Some fish are sensitive to approximately 8 km (5 miles) in length, and all three extend in a southerly direc- is with the University of Valerie J. Smith tion from the dam (Fig. 1). Kincaid Missouri. Columbia; John W. McNurney is with R.W, Becl< and Company, Denver. Colorado. Generating Station, which houses two This chapter submitted iti Oct. 1979. coal-fired 616-megawatt generating 585 586 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 units, is situated between the southern basin morphometry. Only minor ends of the western and middle arms. decreases in temperature occur as the Water is taken from the western (intake) water flows from the plant discharge arm via the short intake canal, used for structure to the confluence of the cooling in the plant, and pumped into discharge and east arms. Ambient water the middle (discharge) arm via the temperatures prevail in the southern two- 1,100-m discharge canal. Water in the thirds of the intake arm and in the reservoir circulates, therefore, in a eastern arm. counterclockwise direction in these two Prior to making the field collections, is not directly in- arms. The eastern arm the effects of an electrical shock on fish volved in the cooling cycle. body temperatures were examined in the When the power plant is of)erating, the laboratory. An available stock of temperature of the cooling water passing laboratory-raised bluegfills was used to through the plant is elevated 7''-10°C, avoid behavior-related activity. Ther- depending upon the volume of cooling mocouples were secured in the vent of a water passing through the plant and the bluegill and at five locations in a large number of units in operation. Water in aquarium in which the fish was confin- the entire length of the discharge arm is ed. The body temperature of the bluegill vertically isothermic due to the design of and the wa-ter temperature were the discharge structure and the reservoir monitored continuously until they Fig 1 — Locations of sampling stations for determining deep body temperatures of largemouth bass and carp at Lal became stable. A 110-volt, 20-ampere approximately 3 km from the power alternating current was then passed plant outfall, fish were most often cap- through the tank, stunning the fish. tured in several large coves that contain- Temperatures were continuously ed groundwater sources in the form of monitored during the electric shock and springs and field tiles. Fish were collected for several minutes afterward while the at Station 5 on all sampling dates except bluegill recovered. In repeated trials, 3 July. In the Station 5 area, where the bluegill of various sizes were used, and discharge canal entered the discharge the duration of the electric shock varied. arm of the reservoir, all fish were taken near the highway bridge approximately Largemouth bass and carp were col- 200 south of the lected for this study from Lake Sangchris, m mouth of the discharge canal. using a boat-mounted alternating-current The bridge structure reduced the cross-sectional electrofishing unit operating at 230 volts area of the middle arm sufficiently and 7.5 amperes. When a fish that weigh- at that point to prohibit the flow of the heated surface ed more than 450 g (1 lb) was captured, the surface-water temperature was water south of the bridge. Therefore, a consistent interface recorded from a continuously operating resulted between the heated water and the ambient electronic temperature probe, and the in- surface water flowing in from the south. ternal body temperature of the fish was Fish were collected only on 10 determined immediately by inserting a June and 3 July at Station 1 calibrated analytical mercury ther- .5 in an area of the intake arm unaffected by the heated discharge. mometer 1-5 cm into the vent. Each fish Fur- was subsequently weighed, measured, ther sampling was discontinued at Station 1.5 after 3 July because the summer and held temporarily to avoid its recap- max- imum temperature ture. Vertical water temperature profiles had already been reached in the intake were measured periodically with an arm and because it was necessary to concentrate collecting electronic temperature probe to estimate efforts in the discharge to the range of water temperatures in the arm capture collecting area. sufficient numbers of fish. Fish were collected from three sam- pling stations on Lake Sangchris (Fig. 1). RESULTS AND DISCUSSION Largemouth bass and carp were taken at Body temperatures measured accord- Station 4.5 on each of the four sampling ing to the methods described were con- dates (10 June, 3 July, 22 July, and 1 sidered accurate indicators of the recent August 1975). At Station 4.5, near the thermal history of the captured fish. central portion of the discharge arm and Muscular thermogenesis, which might Recording the internal body temperature of a carp. 588 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 have contributed a small amount of ex- cess body heat if a fish had recently swum a long distance (Carey & Teal 1969), was considered negligible. The preliminary uj 30 laboratory experiments also showed that a: collecting by shocking with alternating t-< current did not affect body temperatures 01 of bluegills. Since the predominant a- 25h muscles of bluegill, largemouth bass, and UJ carp are physiologically similar, no effect from the collecting technique was ex- 20 pected. Body temperatures were, therefore, considered to be developed on- 40 ly by conductive heat exchange between the fish and the surrounding water at rates dependent on the existing 35- temperature difference between the fish and the water (Fry 1967) and the size, shape, and respiratory rate of the fish (Spigarelli et al. 1974 and Morrow & Mauro 1950). According to data presented by Spigarelli et al. (1974), a 450-g carp or largemouth bass (the minimum size used in this study) would have gained about one-half of a 5°C temperature increase in approximately 4 minutes. Complete temperature equilibrium would have required about 30 minutes, since the relationship is ex- ponential. Therefore, if a fish with a body temperature of 30''C was captured in water at SB^C, that fish must have re- mained in water at least as cool as SO^C long enough to have become equilibrated to the lower temperature. During this study, fish were collected under a variety of water temperature con- ditions relative to the reported preferred temperature ranges of largemouth bass, 29.2»-32.0»C (Coutant 1974, Fry 1950, and Neill 1971), and of carp, 28.3°-32.0»C (Neill 1971 and Pitt et al. 1956). On 10 June, the range of available water temperatures was generally below those preferred temperatures at all three stations. However, most of the lake in the area of Station 4.5 was warmer than the preferred temperatures of both species on 3 July, 22 July, and 1 August. At Station 1.5 on 3 July and Station 5 on 22 July and 1 August, the water temperature range overlapped the preferred temperature ranges of both largemouth bass and carp. Body temperatures of largemouth bass and carp collected on 10 June at all three Aug. 1981 Smith & McNurney: Thermoregulation of Bass and Carp 589 Fig, 3 — Regressions of deep body temperatures (1^) of iargemoutli bass and carp CARP REGRESSION LINE EQUATIONS ,/C2 from Lake Sangchris witfi the (C|)Tb = 0.942xTwt 1.602 P-.OOOI temperatures of the water IC2) Tb- 0.636 « + 5.454 P-.0002 ICjlTb- -O.I98xTw+ 38.184 P-.0007 (T^) from which they were collected. Regression lines Bi _ and Ci represent the o regression equations for - largemouth bass and carp, 5 respectively, at stations 1.5, 5 4,5, and 5 on 10 June. £ Regression lines B2 and C2 I ^b represent the regression ^ equations for largemouth > bass and carp, respectively, o LARGEMOUTH BASS REGRESSION LINE EQUATIONS at Station 4.5 on 3 July. 22 (B|)Tj-0. 843 «Tw» 4.109 P..OOOI -0. 476 xTw + 16.59516. 595 P-.042P July, and 1 August. (BzJTb {B3)Tb'0.338xT»r +20.684 P .116 Regression lines B3 and C3 represent the regression equations for largemouth 28 30 32 34 bass and carp, respectively, WATER TEMPERATURE CO at Station 5 on 22 July and 1 August stations indicated that neither had a par- on 3 July, they were used by some of the ticular temperature preference within the carp and largemouth bass at Station 4.5 range of available temperature (Fig. 2). The water table fell as the sum- (22.0»-29.5»C) (Fig. 2). Internal body mer progressed, reducing groundwater temperatures were widely distributed at discharges and, therefore, the size and each station. number of refuge areas. As the refuges were reduced (22 July) and finally The slopes of lines Bi and Ci (Fig. 3) eliminated August), fewer fish were (regressions of body temperature with (1 able to use thermoregulatory behavior to respect to water temperature at the point escape the high temperatures. This fact of collection for largemouth bass and was indicated by the more restricted carp, respectively) were near 1.0, in- ranges of body temperatures on those dicating a close correlation between body dates and by regression lines Bj and Cj temperatures and surrounding water (Fig. which indicate some ther- temperatures over the entire temperature 3), moregulation because their slopes are range. Mean body temperature was not much less than 1.0. By 1 August, there significantly different (P<0.05) ft-om was no evidence of temperature selection the mean water temperature at any sta- by either species at Station 4.5; all body tion on 10 June (Table 1). temperatures were within the range of Nearly the entire water volume at Sta- water temperatures measured, and the tion 4.5 on all sampling dates after 10 mean temperatures of fish and the water June was above the highest reported pre- where they were collected were not ferred for both teSt species. temperature significantly different (Table 1). Groundwater that entered coves at Sta- tion 4.5 formed pockets of water much Some carp were found in water of cooler than the majority of the water unusually high temperature in the volume in the area. Those pockets acted discharge arm of Lake Sangchris during as refuges from the thermal discharge periods when cooler water was available. and were often too small to find with the Several carp that were collected at Sta- temperature probe. Their presence was, tion 4.5 on the last two collecting dates however, indicated by body temperatures had body temperatures of up to 36.9"C, of fish captured on 3 July which were well well in excess of the upper lethal below the lowest recorded water temperature of 35°-36°C reported for temperatures (Fig. 2). When the refuge carp 2-4 years old (Meuwis & Heuts areas were relatively large and numerous 1957). Although Horoszewicz (1973) 590 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 determined a higher upper lethal from a heated lake subjected to a slow temperature of 40.6°±0.55°C for carp temperature increase of 0.03°C/min m a> E >. T3O a. a> na> >. XI oas T3c " in "3 CD CO .Q 5 m o - 1^ O 0) x.^ 2 —1 'm c 03 O g 2 m If o <" t I" ~ 0) CO 1_ CO CO a> is " I I 0) ^i CO _ •- B ro S Aug. 1981 Smith & McNurney: Thermoregulation of Bass and Carp 591 his test fish became obviously disturbed at consistently near 32°C on 22 July and 1 34.8°C. August, when most of the water at Sta- The maximum body temperature tion 5 was warmer that 35°C (Table 1). recorded for largemiouth bass from Lake The range of body temperatures was Sangchris was 36.7 °C at Station 4.5 on 22 small on both dates, especially in relation July. Several workers have estimated the to the wide range of available water upper lethal temperature that will kill 50 temperatures (Fig. 2). Line B3 and C3 of percent of the population (LT50) for Fig. 3, the regression lines of bass and adult largemouth bass to be in the range carp body temperatures with respect to of 37.2''-38.9<'C (Hathaway 1927, the water temperatures at which they Trembley 1960 and 1961). Although the were captured, had the most gradual body temperatures of Lake Sangchris slopes of all of the regression lines, also largemouth bass did not indicate indicating that the most successful ther- residence at near-lethal temperatures, moregulation by fishes occurred at Sta- some of the individuals captured in the tion 5. would have been ex- coldest refuge areas During the summer of 1975 both lethal temperature changes, posed to largemouth bass and carp at Lake to above 36°C (Hart from about 30°C Sangchris used behavioral thermoregula- 1952), by traveling only a few meters at tions to avoid body temperatures that Station 4.5 on 3 or 22 July or at Sta- July would have been physiologically ineffi- tion 5 on 22 or 1 August. July cient and perhaps even lethal. When Despite the fact that nearby in- necessary, some individuals found and habitable waters had temperatures as low occupied very small volumes of water that as 25.4°C, nearly all the fish captured at had temperatures near the preferred Station 1.5 on 3 July had body temperatures of the fishes. Final prefer- temperatures near the maximum recorded red temperatures for adult carp and water temperature of 32.5°C (Fig. 2). largemouth bass weighing at least 450 g The mean body temperatures of were inferred from body temperatures of largemouth bass and carp were, respec- those fish collected when and where a tively, 32.1°C and 32.5»C (Table 1), in- wide range of water temperatures was dicating that the fish had selected those available in sufficient volumes to permit temperatures. Several carp captured at individuals to thermoregulate freely by Station 1.5 had body temperatures above temperature selection. These criteria for the highest water temperature measured successful thermoregulatory behavior during the collection. Those fish prob- were met at Station 1.5 on 3 July 1975 ably were individuals that had been and at Station 5 on 22 July and 1 August observed in very shallow water, less than 1975. The mean body temperature deter- 0.25 m deep, where they may have en- mined for 16 largemouth bass was countered surface water warmer than any 32.29»± 1.04''C within a range of measured from the collecting boat. 30.3-34.5"C. The body temperatures of Fish collected at Station 5 on 22 July 34 carp collected under the same condi- and 1 August clearly demonstrated tions ranged from 30.2" to 33.5»C with a behavioral thermoregulation. At that sta- mean of 31.79°± 0.76°C. These values tion cool water was supplied by runoff in- represent reliable in vivo estimates of the to the southern end of the discharge arm final preferred temperatures of and the volume was much larger than the largemouth bass and carp. Both are small pockets of cool water formed at Sta- near the highest laboratory tion 4.5. The interface between the cool measurements of preferred temperature water and the thermal discharge formed of 32»C for largemouth bass (Fry 1950) a consistent temperature gradient. The and of 32»C for carp (Pitt et al.l956). mean body temperatures of largemouth They also agree well with the upper range bass and carp captured at Station 5 were of the field measurements of Neill (1971) 592 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 of 32.0»C for largemouth bass and 31 .7°C Carey, F.G. 1973. Fishes with warm bodies. Sci- entific American 228 (2):36-44. for carp. and J M. Teal. 1969. Regulation of body temperature by the bluefin tuna. Comparative SUMMARY Biochemistry and Physiology 28:205-213. CouTANT, C. C. 1974. Temperature selection by fish — a factor in power plant impact assessments. 1. — Based on a review of pertinent Paper presented at I. A. E. A. symposium on the literature and laboratory experiments, physical and biological effects on the physiological effects on the body environment of cooling systems and thermal temperatures of carp and largemouth discharges at nuclear power stations. Oslo. 26-30 bass were determined to be negligible. August 1974. IAEA-SM-18/1I. R. G. 1958. The preferred temperature Body temperatures were, therefore, Ferguson, of fish and their midsummer distribution in considered to be the result of conductive temperate lakes and streams. Canada Fisheries heat exchange between the fish and the Research Board Journal 15(4):607-624. 1937. migration of the surrounding water. Fry. F. E. J. The summer 2. — Predictable rates of body cisco. Leucichthys artedi (Le Sueur), in Lake temperature changes, based on Nipissing. Ontario. University of Toronto Studies. Biology Series 44. Ontario Fisheries temperature differences and physical Research Laboratory Publication 55. 91 p. attributes of the fish, were identified 1950. Temperature preferences and from sources in the literature. cruising speed of largemouth and smallmouth bass in relation to acclimation temperature. 3. — Body temperature measurements Unpublished manuscript. the selection by the fishes of indicated 1967. Response of vertebrate poikilotherms water of certain temperatures, resulting to temperature. Pages 375-409 in A. H. Rose, in behavioral thermoregulation by ed., Thermobiology. Academic Press. Inc.. New- largemouth bass and carp when York. Hart, S. 1952. Geographical variation of some environmental conditions permitted. J. physiological characters in certain freshwater of preferred 4.— When water fish. University of Toronto Studies. Biology temperature was not readily available, Series 60. Ontario Fisheries Research carp and largemouth bass in Lake Laboratory Publication 72. 79 p. Hathaway, E. S. 1927. Quantitative study of the Sangchris were sometimes found to have changes produced by acclimatization on the temperatures near the reported body tolerance of high temperatures by fishes and lethal water temperatures for each amphibians. U. S. Bureau of Fisheries Bulletin species. 43:169-192. 5.— The final preferred temperature HoROSZEWicz. L. 1973. Lethal and disturbing' temperatures in some fish species from lakes with for largemouth bass weighing at least 450 normal and artificially elevated temperature. of g, as indicated by field measurements Journal of Fishery Biology 5:165-181. 32.29" 1.04»C. body temperature, was ± Meuwis. A. L., and M. J. Heits. 1957. Tem- 6.— The final preferred temperature perature dependence of breathing rate in carp. Biological Bulletin 112(1):97-107. for carp weighing at least 450 g, as Morrow, E.. Jr.. and A. Mairo. 1950. Body indicated by field measurements of body J. temperature of some marine fishes. Copeia temperature, was 31.79° ± 0.76''C. 1950:108-116. Neill, W. H. 1971. Distributional ecology and behavioral thermoregulation of fishes in relation REFERENCES CITED to heated effluent from a steam electric power plant (Lake Monona. Wisconsin). Ph.D. Thesis. Bardach, J. E., and R. J. Bjorklund. 1957. The University of Wisconsin, Madison. temperature sensitivity of some American Pitt. T. K.. E. T. GARsmE, and R. L. Hepburn. freshwater fishes. American Naturalist 1956. Temperature selection of the carp 91:233-251. (Cyprinus carpio Linn). Canadian Journal of Bull, H. O. 1936. Studies on conditioned responses Zoology 34:555-557. in fishes. VII. Temperature perception in Spicarelli. S. a.. G. p. Romberg. W. Prepjchal, teleosts. Marine Biological Association of the and M. M. Thommes. 1974. Body temperature United Kingdom Journal 21:1-27. characteristics of fish at a thermal discharge on Aug. 1981 Smith & McNurney: Thermoregulation of Bass and Carp 593 Lake Michigan. Pages 119-132 in]. W. Gibbons denser discharge on aquatic life. Progress report and R. R. Sharilz. eds.. Thermal ecology. AEC 1960. Institute of Research, Lehigh University, Symposium Series (CONF-730505). Augusta. GA. Bethlehem. PA. Tremblfv, F. J. 1960. Research project on effects Zahn, M. 1963. Jahreszeitliche veranderungender of condenser discharge water on aquatic life. vorzugstemperaturen von scholle {Pleuronectes Progress report 1956-1959. Institute of Research, piatessa Linne) und bitterling (Rhodeus senceus Lehigh University. Bethlehem, PA. Pallas). Verhandlungen der Deutschen . Gesellschaft 562-580. . 1961. Research project on effects of con- Zoologischen Lake Sangchris Creel Survey: 1973-1975 John M. McNumey and Herbert Dreier ABSTRACT harvest as a component of a complete For the 2 -year period from April 1973 study of the dynamics of the fish com- to April 1975, a year-round creel survey munity, and to ascertain the effect of was conducted at Lake Sangchris, a elevated water temperatures in the heated cooling lake located in central Illinois, to arm of the lake on the quantity and determine the effects of a thermal quality of sport fishing. discharge on the quantity and quality of Fishing regulations may limit catch. sport fishing. Annual fishing pressure (93 Several specific regulations affected Lake man-hours per acre) was higher than Sangchris during the 1973-1975 creel usual for midwestern reservoirs of similar period. Fishing effort was limited to pole- size. During all seasons of the year, and-line fishing with no more than two fishing effort was concentrated in heated poles per angler and no more than two areas of the lake. The species most hooks per pole. Effort was further actively sought by fishermen were restricted by the closure of the east and largemouth bass and channel catfish. Six west arms of the lake (Fig. 1) to fishing species (largemouth bass, channel during the waterfowl hunting season catfish, white bass, carp, white crappie, from about 20 October to about 5 and bluegill) comprised 78 percent of the December. The harvest of largemouth number and 91 percent of the weight of bass was restricted to no more than six fish harvested. The catch rate and fish per angler per day. harvest of channel catfish were very high in comparison with those of other lakes. DESCRIPTION OF THE INTRODUCTION STUDY AREA A recreational creel survey was begun Lake Sangchris is a 2,165-acre on Lake Sangchris, a cooling lake in cen- (876-ha) cooling lake approximately 16 tral Illinois, on 15 April 1973. The work miles (25 km) southeast of Springfield, Il- was jointly supported by Commonwealth linois. The lake consists of three long, Edison Company and the Illinois Depart- narrow arms with highly irregular shore- ment of Conservation during the first lines (Fig. 1). The middle arm of the lake year. From 15 April 1974 to 15 April receives the heated discharge from Kin- 1975, the survey was funded by Com- caid Generating Station, a 1,232-mega- monwealth Edison Company and super- watt coal-fired generating facility of vised by the Illinois Natural History Commonwealth Edison Company. Water Survey. Although not included in this ternperatures in the discharge canal are report, the creel survey was continued generally 7°-9°C above those in the other through the summer of 1976 (McNumey arms. A more complete description of & Frakes 1979). Kincaid Generating Station and of the physical and chemical characteristics of The creel surveys at Lake Sangchris Lake Sangchris is given by Larimore & served several purposes. The primary ob- Tranquilh (1981). jectives were to measure the public use of the cooling lake as a recreational resource, to determine the sport fishing METHODS The survey technique employed was a John M. McNurney is with R.W. Beck and modification of the methods outlined by Company, Denver, Colorado: and Herbert Dreier is Starrett et al. with the Macon County Public Heahh Department. (1963). It consisted of three Decatur. Illinois. parts: fast counts, fisherman contacts, This chapter submitted in Dec. 1979. and data compilation. Fast counts entail- 594 Aug. 1981 McNuRNEY & Dreier: Creel Survey 595 ed cruising a lake area by boat at high view the creel clerk recorded the type of speed while counting boat and shore fishing, the principal species sought, the fishermen. The clerk worked a total of distance traveled to the lake, as well as about 270, 8-hour days in the 1973-1974 background data detailing date and loca- period by working 6 days followed by 2 tion in the lake. The catch was examined days off. During the 1974-1975 period the and the number and (in 1974 only) total clerk worked 4 days and then was off for 4 weight of each species were reported. The consecutive days. Schedules were design- data were processed on an IBM 360/75 ed to divide counts in each area equally computer using SAS 76.5 procedures among days of the week and hours of the (Barr et al. 1976). Seasonal summaries day in each 3-inonth creel period. The were produced. months were grouped for seasonal sum- Fishing effort in the seasonal sum- maries so that December, January, and maries was calculated entirely from fast February represented winter; March, counts. The predicted fishing effort in April, and May represented spring; June, man-hours was defined as the average July, and August represented summer; number of fishermen in each, hourly and September, October, and November count in a particular category multiplied represented autumn. The logic and ac- by the number of fishable hours per day, ceptability of such seasonal divisions is then multiplied by the number of days in supported by the findings of Malvestuto a particular month. Fishable hours used et al. (1978). in this study were 12 h/day during spring, Fisherman contacts included inter- 15 h/day during summer, 12 h/day dur- views with the fishermen and examina- ing autumn, and 9 h/day during winter. tions of their catches. During each inter- The result was a compilation of fishing MIDDLE ARM (heated) 790 ocres Fig, 1 —The three creel areas of Lake Sangchns, with accessible shorelines indicated by heavy lines. 596 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Taylorville Bass Club member with the day's catch of largemouth bass from Lake Sangchns. effort in each lake area by fishing type tournament data were usually complete, (boat or shore fishing) for each 3-month since the fishermen were censused at the season. Each creel period, 1973-1975, required tournament check-in. Catch was defined as extending from 15 April of rates (fish/h) were determined by one year to 15 April of the next. Bass dividing the catch by the effort. Catch tournament fishing efforts were handled per unit area (fish/acre) was used for the somewhat differently, since the tour- comparison of harvests from the three naments were closely controlled by the arms of Lake Sangchris and with data sponsoring bass clubs. Those efforts were from other lakes. calculated from observations of the tour- The species sought by fishermen were nament conclusion (weigh-in) by the creel determined during the interview period. clerk. Since the various sections of Lake Those people who were not trying to Sangchris have different areas, the effort catch a particular species were included per unit area (man-hours/ acre) was deter- in a "no preference" category. Predicted mined for each area, fishing type, and effort expended on each species in each season. All data are presented in English arm by boat and shore fishermen was units to facilitate comparisons with other calculated by multiplying the effort of in- published data, which have been terviewed fishermen by the expansion customarily expressed in such units. factor. Several frequency distributions of Projected catch data were calculated fishing party contacts were also created. by multiplying the actual catch data by These included separation by distance an expansion factor individually calcu- traveled to the lake, time of day, and lated for boat and shore fishermen from habitat fished. each area in each creel period. The ex- The three arms of Lake Sangchris pansion factors used in this study were were surveyed as if they were separate calculated by dividing the projected bodies of water (Fig. 1). The middle arm fishing effort in a particular category by of the lake from the power plant the effort (man-hours) expended by con- discharge to the dam area was considered tacted fishermen in that category. Bass the heated area. It had a surface area of Aug. 1981 McNuRNEY & Dreier: Creel Survey 597 790 acres. The west and east arms, which hours (47.9 percent) was estimated for have areas of 707 and 373 acres, respec- the summer of 1974. Such a seasonal use tively, were designated unheated areas. pattern (Fig. 2) is typical for midwestem Both unheated areas had similar lakes (Kathrein 1953, Snow 1971). The temperature regimes and were only annual fishing pressure of about 93 man- slightly influenced by the heated hours per acre is higher than the range discharge. reported for reservoirs of similar size (Kathrein 1953, Rawstron & Hashagen RESULTS AND DISCUSSION 1972) and higher than values reported for FISHING EFFORT Thomas Hill Reservoir (7.0-28.4 man- hours/ acre), another heated midwestern Since this study was based on a creel reservoir (Hanson 1974). It is similar to survey rather than a complete census, the effort recorded for lakes of less than many fishermen were neither contacted 500 acres (Snow 1971, Mraz & Threinen nor counted on the lake. An estimate of 1957). effectiveness of the methods used and, the Most of the fishing pressure was con- consequently, an evaluation of the centrated in the heated area of the lake, reliability of the projected data, were the middle arm, during all seasons (Fig. made by determining what portion of the 2). In fact, 58.4 percent of the fishing ef projected total effort was expended by fort during the 1973-1975 creel period fishermen actually contacted by the creel was expended in the middle arm, which clerk. The contact ratio, or percentage comprises only 42.2 percent of the area. contacted, varied between seasons, areas, Hanson (1974) observed similar use pat- and fishing types (Table 1). terns in Thomas Hill Reservoir, a coohng contacting a particular The possibility of lake in Missouri. During winter, early is proportional to the length of fisherman spring, and late autumn fishermen were his the lake the amount of stay on and attracted to the heated areas of the lake time available for the creel clerk to con- because the higher temperatures were ex- is propor- tact fishermen. It inversely pected to keep fish active and feeding. fishermen tional to the total number of During the summer, anglers seemed to be time. generaliza- on the lake at one These drawn to the discharge arm merely tions apply within certain limits. Since because it was the single unusual shore fishing trips are usually shorter character of the lake. The use rate of the than boat trips, the contact ratio for northern half of the middle arm was in- is usually lower (5-56 shore fishermen creased by shore fishermen, who used it = 12.8 percent) than for percent; mean heavily, owing to the large amount of ac- boat fishermen (10-83 percent; mean = cessible shoreline in that lake area (Fig. 29.4 percent). The highest contact ratios occurred during winter and early spring, Fisherman use varied daily and the periods of lowest use, and the lowest seasonally. During spring, summer, and ratios occurred during late spring and autumn, people fished the lake at summer, the periods of highest use. The relatively even levels of effort between usage and contact ratios measured dur- 0800 and 1900 hours. (Fig. 3). Fishing ing the autumn periods were in- was concentrated during the warmest termediate. The contacts in all arms of part of the day in winter. Most fishing oc- the lake varied similarly within seasons. curred at Lake Sangchris in May, June, Between 15 April 1973 and 15 April and July in the 1974-1975 period (Fig. 4). 1974, an estimated 191,680 man-hours The lowest monthly totals occurred dur- were spent fishing at Lake Sangchris. In ing December and January. Monthly data the 1974-1975 creel period, 147,524 man- breakdowns were not available for the hours were spent there. More than 46 1973-1974 period. percent (88,903 man-hours) of the The distance traveled by fishermen to 1973-1974 total was expended during the use Lake Sangchris was documented in summer months of June, July, and an effort to produce an economic evalua- August. Similarly, a total of 70,597 man- tion of the resource by a method similar 598 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 oocoo w^DO r>.ao 6? 00 ^ OJ r* o^ r- O ij 6? 2 o^ 6? - .!2 cn o OJ to £ S 5> E " fc c 3 ra M w CO m<„ I 0) 0) o Aug. 1981 McNuRNEY & Dreier: Creel Survey 599 60 r UNHEATED HEATED I I - ^ 10 fN^ rl SPRING SUMMER AUTUMN WINTER SPRING SUMMER AUTUMN WINTER SPRING 1973 1973 1973 1973 1974 1974 1974 1974 1975 Fig. 2. —Seasonal distribution of fishing effort (man hours/acre) between unheated and heated areas of Lal to that employed by Gordon et al. (1973). unchanged throughout the year (Table Because the vast majority of people 3). The minor differences apparent in the fishing the lake lived within the nearest winter were probably due to the occur- zone of record, such a graphical assess- rence, in that small sample, of bass club ment was mathematically impossible. fishermen, generally middle-aged males. Between 66 and 79 percent of fishermen Most fishermen were males (78-96 per- contacted each season lived less than 25 cent). The lowest percentage of fishing miles from Lake Sangchris (Table 2). On- females occurred in winter and the ly 6-12 percent (mean = 9.4 percent) highest occurred in summer. traveled 50 miles or more to the lake dur- Most of the fishing effort at Lake ing spring, summer, and autumn. During Sangchris during the creel period was ex- winter, 23 percent of the fishermen were pended in search of largemouth bass and from 50 or more miles distant, indicating channel catfish (Table 4). The annual ef- the attractiveness of the winter fishery. fort from June 1973 to June 1974 was Many of those were bass club fishermen 56,476 hours seeking largemouth bass from Champaigfn, Peoria, Bloomington and 19,134 hours for channel catfish. (75-99 miles distant), and Decatur (25-^9 During that period the total time spent miles). on the next four most desirable species (white bass, carp, white crappie, and Data from interviews with fishermen bluegill) was only 25,700 hours. For each were used to describe the fisherman species, the fishing effort was distributed population. The age composition of the differently between lake areas and fishing population remained relatively seasons. 600 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 30 Aug. 1981 McNuRNEY & Dreier: Creel Survey 601 Table 2. —Seasonal summary of the distance traveled by fishermen to Lake Sangchris (percentage of season total) for the 1973-1975 creel period. Distance 602 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 a o Aug. 1981 McNuRNEY & Dreier: Creel Survey 603 604 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 6. — Predicted annual fish harvest data for Lake Sangchris for the 1974-1975 creel pericxl (15 April 1974-15 April 1975)^ Aug. 1981 McNuRNEY & Dreier: Creel Survey 605 o IN eg E^ 606 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 LflRGEMOUTH BASS Fig. 5 —Total catch rates of largemouth bass at Lake Sangchrls for untieated and fieated areas from April 1973 througti April 1975. were somewhat lower than rates reported heated area during 1973. Throughout for Lake Shelbyville, a lake of much the year the harvest in the heated area larger size (McNurney 1978). was consistently higher than that in the Catch rates for white bass (fish per unhealed areas. Since most carp were man-hour) were high in cold months and caught by shore fishermen, the reduced low in warm periods (Fig. 7). The highest harvest in the unhealed areas may be cor- catch rates occurred in the heated area of related to the minimal amount of the lake. Catch rates improved at Lake shoreline accessible to anglers there. The Sangchris during 1976 and 1977 as the annual harvests of 2.95 and 2.01 fish per angling population became more ac- acre in 1973 and 1974, respectively, were customed to fishing for this recently in- comparable to the 2.67 fish per acre troduced species (McNurney & Frakes reported for Thomas Hill Reservoir 1979). (Hanson 1974). Summer harvest values for the unhealed areas of Lake Sangchris Carp were 0.67 and 0.55 fish per acre for 1973 The number and biomass of carp and 1974, respectively. McNurney (1978) harvested in various areas of Lake reported summer harvests for Lake Sangchris between 15 April 1973 and 15 Shelbyville of 0.17 and 0.30 fish per acre April 1975 are compiled in Table 10. In in 1976 and 1977. Summer harvests of winter, carp were caught only in the carp from the heated area of Lake CHANNEL CATFISH Fig 6. —Total catch rates of channel catfish at Lake Sangchris for unheated and heated areas from April 1973 through April 1975. Aug. 1981 McNuRNEY & Dreier: Creel Survey 607 CTi t^OOO WC^O^ ^-C^OO lOi—r^ o ^ -^ IN Ol ^ oo^-o r^ooif) tor^oo r^r-^ o -^ in o^oo r^oir^ oo^o otni^ ooo o.—'C^j ooo cioo o — .— o^-^- oo.— ooo ooo < a •PI B 3 608 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 O Tj* rf « If) «B iO 00 "T 00 in oo Tf oo r* -f r^ CM — in ^ r^t^ rf ^^ tTi CTlOO — in^o OO CO t-- (N cxi o to ^ CX) 00 oo w <£0 en -~t Tf rf c^ 04 ^O'* o ^ ^ o o ^ O — G^ o^- ooo — OM ooinoo o. ooo ooo ooo ooo < ooo ooo ooo ooo ooo o Q. < ooo (NiMTf Oinifi •— ao a^ ^o^ ^^ a^ in ^r^^n ko at xn tooiin c^iO).—" o^Tj o t^ r* r>.oiio aoto^r oojov M on^-inr-r-»CTi(0 .— — M oo to CO to o II to :3 o 5 to OT to CD E ^ to T3 oj to ii to cp D p o ^ .9i I S ™ 03 O I- J2 13 o 0; C U ft. Aug. 1981 McNuRNEY & Dreier: Creel Survey 609 003 WHITE BASS Fig. 7, —Total catch rates of white bass at Lake Sangchris for unhealed and heated areas from April 1973 through April 1975. Sangchris during the 1975-1975 creel vary from year to year, as evidenced by period were much higher at 2.40 and the range of values from Thomas Hill 1.33 fish per acre. Reservoir of 0.34—26.75 fish per acre in a Catch rates for carp were generally 5-year period. The white crappie harvest variable in 1973 and 1974 in the heated at Lake Sangchris was well distributed and unheated sections of Lake Sangchris between the heated and unheated areas (Fig. 8). They were highest in spring and in all seasons. summer and usually very low in winter. White crappie catch rates varied con- The catch rate in the heated area was siderably between years, seasons, and consistently greater than or equal to the areas (Fig. 9). No trends could be con- rate in the unheated area. fidently identified because the occurrence of crappie catches was low and the sizes of White Crappie those catches were highly variable. The sport fishing harvest projections for white crappie in various areas of Lake Bluegill Sangchris are shown in Table 11. These Harvest projections for bluegill, a data were included because crappie fre- popular sport fish in many Illinois lakes, quently constitute an important part of are described in Table 12 for various the sport fishery of a midwestern reservoir areas and seasons. The number harvested and because this species was apparently per acre (7.89-11.16) (Tables 5 and 6), once an important game fish in Lake was much higher than that recorded for Sangchris. Thomas Hill Reservoir (0-0.83 fish per In the 1973 and 1974 creel periods, acre with a mean of 0.26 fish per acre) by respectively, 6,405 and 5,145 crappie Hanson (1974) or for Lake Shelbyville were caught in Lake Sangchris (Tables 5 (summer only, 0.35-0.50 fish per acre) by and 6). These figures correspond to McNurney (1978). The catch at Lake harvest rates of 3.43 and 2.75 fish per Sangchris was, however, composed of acre, values comparable to the 2.53-4.57 small individuals (0.91-1.29 pounds per fish per acre reported for Barren Reser- acre) (Tables 5 and 6) averaging less than voir, Kentucky (Carter 1969) and well 0.12 pound per fish. Most of the bluegill below the 5-year mean for Thomas Hill harvest was taken during the spring and Reservoir of 10.09 fish per acre (Hanson summer months and was divided nearly 1974). Crappie populations notoriously equally between the heated and unheated 610 Illinois Natural History Survey Bulletin Vol. 32, An. 4 -f < Q. < Q. E o w vr o "o CD cn c: CO 13 CD C/) CO o -o E CD ^ ™ -5, CD CJ) J= CD o S ss T3 CO CD *- .S: CD CO > iEto => o E'^ O "D ClJO O " ^~ (1) C/D »- CO CD .O CD CO o OJ CO .Q CO E -o ? " C c/: ~ CO M E CD>5O " CD •^ sz -D H CD t3 ^ 2 "i Q_ ^ I % '" C/) CO CO o X3 U a. — Aug. 1981 McNuRNEY & Dreier: Creel Survey 611 - 5c0.06 HEATED ' z \ < ^ ARE»-^ / s Fig. 8. —Total catch rates of carp at Lake Sangchris for unhealed and heated areas from April 1973 through April 1975. Fig. 9. —Total catch rates of white crapple at Lake Sangchris for unhealed and heated areas from April 1973 through April 1975. BLUEGILL Fig. 10. —Total catch rates of bluegill at Lake Sangchris for unhealed and heated areas from April 1973 through April 1975. 1 4 1 1 1 1 1 1 1 1 asondIjfmam N 01 J F M A 1975 612 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 CO en m Aug. 1981 McNuRNEY & Dreier: Creel Survey 613 00 C^ O Oi — o QOTfcj moooo ^-tNcn —' en t an fN U2 in CN oo iD ai on.—"iD ~^ -^ <£> OlO^CO iDI^CM ^- ^ — lO — o — o — .— CMQOO cNcnic OQoai o O CO CO CM 00 O OOO «<£)00 Ot^I>- ooo o 614 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 areas. Since shore fishermen were respon- higher than typical fishing- pressure levels sible for most of the catch, most bluegill for midwestem reservoirs of similar size. were caught in the heated area because of 2 . — Fishing efforts were consistently the considerable amount of fishable concentrated in the heated area of the shoreline there. lake in all seasons. Catch rates for bluegills generally 3. — Largemouth bass and channel declined from 1973 to 1975 (Fig. 10). catfish were the most sought-after species Very few fishermen actively sought in the lake. bluegill; most were caught while anglers 4. — Most of the total sport fishing were fishing for other species. The catch harvest (78 percent by number and 91 rate in unhealed areas was consistently percent by weight) was composed of somewhat higher than in the heated area. largemouth bass, channel catfish, white Catch rates were generally higher than bass, carp, white crappie, and bluegill. the 0.022-0.025 bluegill per hour report- 5.— Channel catfish harvests and ed for summer periods at Lake Shelbyville catch rates in 1973 and 1974 were very (McNurney 1978). high in comparison with those of other lakes. SUMMARY AND 6. — White bass harvests were low, CONCLUSIONS probably because white bass had only 1.— During 1973 and 1974, annual recently been introduced in Lake fishing pressure at Lake Sangchris was Sangchris. REFERENCES CITED Goodnight, P. Sall, andj. T. Unpublished report to the Institute for Barr, a. J, J. H. J. Helwig. 1976. A user's guide to SAS 76. Environmental Studies. University of Illinois, Statistical Analysis System Institute, Inc., Urbana. Raleigh, NC. 329 p. . and M. Frakes. 1979. Recreational creel Sangchris: midwestem cooling Carter, J. P. 1969. Pre- and post-impoundment survey at Lake a surveys on Barren River. Kentucky Fisheries lake, 1975-1976. Pages 6-1 -6-39 m Evaluation Bulletin 50. 33 p. of a cooling lake fishery. Vol. III. Prepared Gordon. D.. D.W. Chapman, and T.C. Bjorn. by Illinois Natural History Survey for Electric 1973. Economic evaluation of sport Power Research Institute. Palo Alto. CA. fisheries— what do they mean? American Mraz, D., and C.W. Threinen. 1957. Angler's Fisheries Society Transactions 102(2): 293-311. harvest, growth rate and population estimate of Hanson. W. D. 1974. The fishery of a Missouri the largemouth bass of Browns Lake. reservoir receiving thermal effluent. Wisconsin. American Fisheries Society Southeastern Association of Game and Fish Transactions 85:241-256. Commissioners Proceedings for 1973, 27: Rawstron. R. R., and K. A. Hashacen. 1972. 722-734. Mortality and survival rates of tagged Kathrein, J.W. 1953. An intensive creel census on largemouth bass (Micropterus salmoides) at Clearwater Lake, Missouri, during its first four Merle Collins reservoir. California Fish and years of impoundment, 1949-1952. North Game 58(3):221-2S0. American Wildlife Conference Transactions Snow, H. E. 1971. Harvest and feeding habits of 18:282-295. largemouth bass in Murphy Flowage, 1981. Wisconsin. Department of Natural Resources Larimore, R. W., and J. A. TRANftuiLU. The Lake Sangchris project. Pages 279-289 m Technical Bulletin 50. 25 p. Tranquilli, eds.. R. W. Larimore and J. A. The Starrett, W.C, A.C. LopiNOT, and L. Rock. Lake Sangchris study: case history of an Illinois 1963. 1962 Mississippi River sport fishing creel cooling lake. Illinois Natural History Survey census procedures. Illinois Department of Bulletin 32 (4). Conservation. Division of Fisheries. 90 p. Malvestuto. S.P., W.D. Davies. and W.L. TRANftuiLLi, J.A.. R. Kocher. andJ.M. McNltiney. Shelton. 1978. An evaluation of the roving 1981. Population dynamics of the Lake creel survey with nonuniform probability Sangchris fishery. Pages 415-499 in R. W. sampling. American Fisheries Society Larimore and J. A. Tranquilli, eds.. The Lake Transactions 107(2):255-262. Sangchris study: case history of an Illinois McNurney. J.M. 1978. Survey of fishing and other coohng lake. Illinois Natural History Survey water based recreation at Lake Shelbyville. Bulletin 32(4). Distribution and Abundance of Larval Fishes in Lake Sangchris (1976) Harry Bergmann ABSTRACT upon fish reproduction by describing the spatial and temporal distribution of lar- The distribution and abundance of val fishes within the cooling loop and (2) larval fishes were studied in Lake to compare the relative abundance of lar- Sangchris during the spring and summer val fishes in the intake and discharge of 1976. Gizzard shad (Dorosoma cepe- canals. dianum) and Lepomis spp. were the only two taxonomic groups captured in ade- DESCRIPTION OF quate numbers for statistical analysis. THE STUDY AREA Morone spp. were also collected but ac- Lake Sangchris is an 876-ha counted for only 1.6 percent of the total impoundment located in central Illinois catch. Gizzard shad densities were highest and provides cooling water to a in similar habitats (coves and mouths of 1,232-MW coal-fired electrical creeks) from both the discharge and in- generating plant. Water that passes take arms. Densities of Lepomis larvae through the plant's condensers is were highest in the discharge arm. For discharged into the middle branch gizzard shad and Morone larvae, Httle (discharge arm) of the lake (Fig. 1). difference was observed in the temporal Water circulates around a 16-km "cool- appearance of larvae in the discharge and ing loop" and re-enters the plant via the intake arms. In the discharge arm a peak west branch (intake arm). The east in the numbers of Lepomis larvae occur- branch (control arm) is not part of the red 1 week earlier than in the intake cooling loop. A more detailed description arm. Low numbers of gizzard shad and of Lake Sangchris can be found in the in- Lepomis larvae were found in deep water troductory chapter of this monograph. in the intake canal arid indicated that few larvae were vulnerable to entrainment during the daytime. Gizzard MATERIALS AND METHODS shad larvae were collected during a Larval fishes were collected at weekly 24-hour vertical migration study by intervals during daylight hours from 19 taking tows at the surface, 1-, 2-, and March to 5 August 1976 from 10 stations 3-meter depths at 3-hour intervals. in Lake Sangchris (Fig. 1). The stations Gizzard shad densities were highest near used in this larval fish study do not cor- the surface during daylight and highest respond with collecting stations used in near the bottom at night. other Lake Sangchris studies. Stations 1-5 were located in the discharge arm and INTRODUCTION stations 6-10 were located in the intake arm. Larval fishes were not collected A larval fishes study was conducted in from the control arm because water Lake Sangchris during the spring and temperatures there are similar to those in summer of 1976. The objectives of the the intake arm. Stations were selected study were: (1) to evaluate the impact of primarily according to habitat types the heated effluent from the power plant which might be utilized as nursery areas. Comparable stations were selected from Harry Bergmann is with Southern Illinois University. Bradley, Illinois. the discharge and intake arms and in- This chapter submitted in Nov, 1978. cluded coves, midchannel areas, mouths 615 616 Ilunois Natural History Survey Bulletin Vol. 32. Art. 4 t 1 km I m I / Plant Fig. 1 — Larval fishes sampling stations at Lake Sangchris (1976). of tributaries, and intake and discharge paired No. 00 mesh (0.75 mm) conical canals. plankton nets from the bow of a boat. Tows were taken at the surface and at The nets were 3.5 m in length with an 2 and 4 m where there was sufficient opening diameter of 0.5 m. At the cod depth. Stations where only one surface end, a modified plankton bucket with tow was taken are designated by the sta- aperture screen of No. mesh (0.571 mm) tion number alone. Where more than one was attached. A General Oceanics model surface tow was taken, the letter m 2030 flowmeter was placed in the mouth designates a midchannel sample. The let- of one of the paired nets. All nets were ters e, w, and s designate tows along the towed for 3 minutes at a boat speed of ap- east, west, and south shorelines, respec- proximately 1.3 m/sec. tively. Deepwater tows of 2 and 4 are m Samples were preserved in a buffered designated by the superscript 2 or 4. 5-percent solution of formalin and Supplementary tows were taken on 28 returned to the lab to be counted and May to study vertical migration. A sam- identified. In samples where 30 or more pling site- was selected near Station 8 larvae were collected, a representative because the water was uniformly 4 m subsample of 30 larvae was obtained for deep. Samples were collected over a length determination and enumeration of 24-hour period at 3-hour intervals at the pro- or postlarvae. All identifications and surface, 1-, 2-, and 3-m depths. terminologies follow the key of May & Larval fishes were collected by towing Gasaway (1967). Aug. 1981 Bergmann: Larval Fishes 617 Data were expressed as the number of no significant difference between the fish per 10 m' of water filtered, and number of larval shad collected at Station were transformed into logarithms to 2, in the discharge arm near the mouth of stabilize the variance for statistical the middle branch of Clear Creek, and analysis. One unit was added to all data the two cove stations 3 and 6. The before transformation so that zero values relatively high density of larvae at these could be included and to eliminate four stations in coves and mouths of negative logarithms. A two-way analysis creeks from both the discharge a^d in- of variance (ANOVA) was performed on take arms indicated that the thermal ef- the number of larvae collected and the fluent had little influence on their spatial least significant difference (LSD) used as distribution, and that habitat preference the test for significance between station may have been the dominant factor in means (Snedecor & Cochran 1967). gizzard shad reproduction in 1976. Little difference was observed in the RESULTS AND DISCUSSION temporal distribution of gizzard shad be- intake arms (Fig. During the weekly larval fishes collec- tween the discharge and estimated that tions, 35,007 larvae were captured, 2). Nelson & Cole (1976) temperatures within the representing fiv^ ta-xonomic groups. The increased water at Monroe, Michigan, most abundant species collected was giz- discharge system period zard shad, constituting 89.4 percent of may have extended the spawning months. However, in the total catch. Lepomis spp. and Morone of gizzard shad by 2 extended spawning spp. accounted for 9.1 and 1.5 percent of Lake Sangchris an not evident. Larval gizzard the catch, respectively. One freshwater period was on 22 April at drum (Aplodinotus grunniens), one carp shad first appeared (Cyprtnus carpio), and one unidentified 4 stations in the discharge arm (stations cyprinid were also captured. During the 1, 2, 3, and 4) where water temperatures 20.4° at Sta- vertical migration study totals of 6,684 ranged from to 23.7''C and canal gizzard shad and 26 Morone larvae were tion 9 located in the intake where captured. the water temperature was only 17.8"C (Table 3). Bodola (1966) reported that in Power production (gross generation of western Lake Erie gizzard shad spawn electricity) by the Kincaid Generating between 17" and 23''C. The highest den- Station was abnormally low during the sities of gizzard shad larvae in both arms spring of 1976 (Larimore & Tranquilli were found from 27 May to 10 June. The 1981). In more normal years, increased mean catch in the intake arm during this power production could elevate water period was heavily influenced by the large temperatures in the spring above those number of larvae collected at Station 10. observed in this study, thus having a Prolarvae were last captured in the intake greater effect on the time of spawning. arm on 10 June and 1 week later in the discharge arm. Low numbers of gizzard GIZZARD SHAD shad larvae were collected from both Gizzard shad larvae were captured arms on 7 July. Numbers remained low in from 22 April to 30 July (Table 1), and the next three weekly collections until 5 ranged in total length from 3 to 37 mm. August when no larval shad were col- Of the 30,615 gizzard shad larvae col- lected in either arm. lected, 74 percent were captured between At the three stations where 4-m tows 27 May and 10 June. were taken, densities of gizzard shad lar- Larval gizzard shad were most abun- vae were lower at the 4-m depth than at dant at Station 10 in the intake arm near the surface or the 2-m depth (Table 2). the mouth of a tributary (Table 2). On 4 Of all stations sampled, the density of lar- June, 10,673 gizzard shad (35 percent of val shad was lowest at the 4-m depth in the total collected) were collected in one the intake canal (Station 9*). Within the 3-minute tow at this station. There was intake canal, the number of larval shad 618 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 o cO) o o c ro ro c " , Aug. 1981 Bergmann: Larval Fishes 619 O w 00 en 00 o o 2? r- o ^ — oo ^ooooooii—'oo oooooon -in -^ '^ '-"^OOffJosi'-' 's}ir-^i-H(^ '— o .-iOiftootooDon.—'Oioooooint^ooiM — (N iDin oriof>00(NO^r>-'^0^00'^'^GMOCNOO^if)'*r OOOT) on (N c^j ift on Tj" on ;oonooo-)^XioOG^Tfr-..CT)iric^iaiO'—'O oomoncM 'O 'o—"O0^^£)^fl^-^0»- -ri -QOtoa)QOo^^ooonQOO^on—'^^-in -oio -on -oifi.— oooinG^o»otCi^M t^8noniftonoinoioo N'*otDinr^r»a^^^oor>.oooiDr-r>-Tj"x>t^on ^or*^^wonr*r-oootDiniftoo TfcoTf'^ o 0*n'-''--os)^cb(Nint^^(Nixr»OJ-- "oooo o tooo^-i'^'^ooonminiAto>-Ha^i-^oo kd !> id in in^^DtoonNQOO^or^ono^-TpCTiOi -irio^onon n (Nonon(N^CTiodior-'f-onin>—•Tf'.—t.—I o^hoo (0 ^^ oONoo^-onon<—' • to ao<^Tt'oo<— ^oono^o—^^ojr^^^t^ -o • o -tDfTir^r^^Ot-",—iTj",-.oonoo^cNif){N -on 'on 'o^Hoo^cirJai-^t—a6^^c^CT>r»irioo o r-^ ^ ^ (M ^ C) ooi^onoo^-oo ono^^iow'^r*-'^c^oocMa>oooimt^Qoa*0(Nr-o^onif)Qoooao oooo^in^on^ Oin—I^adt^-'j'onQoaiod'^on'^ Tt-wi-H.—.woo 1—1 .-I (M '^ i—' r^ onooo>oan^in^ooxit>-onoin -^doooonn -oo ononQOtoo»' ooioifttooo^O'—'O^oon^Ho^oiftoooiciooio -o ooon—ion<—<(N(NooQO(oaion^'^(Nontnr>-' i 3 620 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 collected at the 4-m depth (Station 9*) was •^ r^ O significantly lower than the number col- OO C>J oO r>- cxj on lected at the surface (Station 9), along the shore (Station 9s), and at the 2-m depth (Station 9»). This difference is particularly important because when Lake Sangchris is at normal pool, the cooling water is drawn from 6 m below the surface. If the larvae maintained this vertical distribu- tion at the intake structure, few larvae would be vulnerable to entrainment There were no significant differences o (.o on 00 w r>- in larval shad collected at " rf ^ a> in the number of — 00 o o the 4-m depth in the intake canal and the number collected from the discharge canal stations. However, the relationship between the numbers of larvae collected at those locations and entrainment is not well understood. Marcy (1973) observed that dead entrained larvae at a nuclear power plant in Connecticut began set- tling out in the discharge canal. Fewef < dead larvae were collected at his lower lO O Tt" »£) discharge station than at his upper 3 O 3 discharge station. Similar results were & reported by Nelson & Cole (1975), who found yellow perch were most abundant near the surface at lake and intake sta- 0} o tions, but in the discharge canal the ma- jority of larvae were collected near the bottom. In Lake Sangchris, irregularities in the bottom contour prevented subsur- & face collections in the discharge canal. The relationship was further complicated oo iM y^ t^' -" csi .-« r^ by an inability to separate entrained from non-entrained larvae. Water velocities at the mouth of the discharge canal were considered strong enough to prevent recruitment of the smaller larvae from outside the discharge canal; " ji however, some spawning may have occur- the shore within the canal. O o -a red along CO 'eo a. the vertical migration study, >. 8 During a 6,684 gizzard shad larvae were captured ranging in size from 4 to 21 mm in total CM length. Four collections during the ,.^ C 0) 24-hour study were made during J3 c 2. three at night, and one at dusk •2 I, daylight, (1900 h) (Fig. 3). The mean catch from « Q .S W I Aug. 1981 Bergmann: Larval Fishes 621 125.5 = INTAKE ARM A / \ -= DISCHARGE ARM J. A_ T T / \ 1 T 1 1 1 1 r 1 — r 15 22 29 6 13 20 27 ^ 10 17 24 7 15 22 30 5 APRIL MAY JUNE JULY AUGUST Fig 2. —Mean catch of gizzard shad larvae in the discharge and intal (Bridger 1956). This avoidance is depen- therefore, densities calculated from week- 622 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 mojoONoo^-'^ooo^O'^oi.ooooaOTj'oiootD ,—),_,.«,«.—I.—I—I—I,—•C^C^)(N inM—'CO>—"Owoo^ooi^'^inr^^'^^OJOQO TO CO CT)i—'inMinoor>-c^inQO'—^irt^^r^-oocMM QOQO^t^O^^eOtOoOOiDO'—'OOt^^noOC^J^^- inaoo^ifj^^^fiooiOCT^iDOo'^oO'— c^emooo^ooooo ooa)0'^'^r*>oOQOOOoaor*if)Oao^»r)—'Qoor* Q. E 0) CO Aug. 1981 Bergmann: Larval Fishes 623 u~ E o 624 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 - 00 . . . Tt* o oo on • do'oo on Qo 0000 -<£)'>j'oiinaOi—-r-r* -onon -MNonoocMN do 'G>'^i-^cic^'-'Gci ' .^0^0(^^^D o^o^coon ' d d> ^ d> C/3 »o on oo CTi -on ff) 00 to o o O — tf) "^ (M r* ^ -on eg If) 00 CTi an ^ «5 d —" (N M I— ' d o o o o o ;o on ift o 00 ^ — —• CTiCNiDor>.r>-^o ' d c^ (N d ^ lO T3 T3C o o >CO w S o Q. 0) E-ri 3 C CO 0) H >CD Aug. 1981 Bergmann: Larval Fishes 625 CTit—'tnific^]-—'OOOOOOGMon© OW—'^tN^OOO o ^ ^ OO^ONOOOO^^WO^OO Oo I (6 — oooocMincNQO onosiinoJiDonoo ontNOtNOOO ooooooo •^j'ooo^— -tor-io—'(NOO'-«r^ooai CM^"—"(N O-—'OOOlOMOJOOO O'-'OO '^^OOO*-"—" '.-lorioo 0^^(O^^OW <(0<« S) , 626 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 larvae catch while only contributing 13 percent to the total number of larvae (3-37 mm) captured. During the vertical migration study, the lengths of larval gizzard shad cap- tured in daytime collections also decreas- ed with depth (Table 5). However, during the nighttime collections, lengths increas- ed with depth except near the bottom at 3 m. Apparently, large larvae were con- centrated near the surface during the day p- on QO r. Tj- -^ oi ffi — and moved into deeper water at night. S 2. LEPOMIS LARVAE Bluegill (Lepomts macrochirus) green sunfish {Lepomis cyanellus) and their hybrid are the only three Lepomis species in Lake Sangchris (Tranquilli et al. 1981). Bluegill are by far the most abundant; however, because of the similarities of the Lepomis larvae, iden- tification to species was not made. Lepomis larvae were collected from 27 May until 5 August when sampling was terminated (Table 6). Of the 3,800 Lepomis larvae collected, only 20 were captured at depths of 2 and 4 m; conse- & quently, the subsurface tows were disregarded in the statistical analysis. Ap- parently larval Lepomis remain near the surface during the day. Total lengths of Lepomis larvae cap- o £ o tured ranged from 4 to 14 mm. No pro- & o larval Lepomis were captured during the study. Werner (1967) reported that bluegill larvae migrate from littoral to limnetic habitats soon after absorption of the yolk sac. The design of the sampling gear used in this study prevented effective sampling in littoral areas and may therefore be responsible for the absence of prolai^vae in the collections. Lepomis larvae were most abundant in the discharge arm at stations 2 and 3 (Table 7). The largest single collection was made at Station 3 on 10 June when 1,139 Lepomis larvae (30 percent of the total) were captured. Lepomis larvae were Si . o ^ « 5 "s ?i also abundant in tows taken along the t« o > Aug. 1981 Bergmann: Larval Fishes 627 west shoreline at Station 4. Collections in small numbers when collections were from the discharge arm at stations 2, 3, terminated on 5 August. and 4w were responsible for 69 percent of MORONE LARVAE the total Lepomis catch. Large populations of both white bass At stations 4 and significant dif- 7, (Morone chrysops) and yellow bass ferences were found between tows taken {Morone mississippiensis) occur in Lake the west shoreline and tows taken from Sangchris. White bass are an important from the middle and east shoreline. In sportfish, whereas yellow bass are not. both instances, the west shoreline had According to a recent larval fishes iden- significantly higher Lepomis densities. tification key (Hogue et al. 1976), no Although visual observations suggested means have been devised for separation apparent difference between the east no of the two species. and west shorelines, the west bank might Between 15 April and 10 June, 589 have provided some shelter from the Morone larvae were collected (Table 8). predominantly southwest winds, pre- Total lengths of Morone larvae captured venting wind and wave dispersion. ranged from 3 to 20 mm. Morone larvae The earliest date when Lepomis lar- were first captured on 15 April in the vae were captured in the discharge arm discharge arm at Station 2 where the sur- was 27 May at stations 2, 4, and 5, when face water temperature was 19. PC. surface water temperatures ranged from Morone larvae were captured in the in- 23.0° to 24.5°C (Table 3). Larval take arm 1 week later at stations 8,9, and Lepomis were captured 1 week later in 10 where surface water temperatures the intake arm (Station 7), when the sur- ranged from 16. S" tol7.8»C (Table 3). face water temperature was 21.3°C. Peak Morone larvae were captured last on 10 catches occurred on 10 June in the June in both arms. Although there was a discharge arm and 17 June in the intake 1-week difference in the onset of spawn- arm (Fig. 4), indicating a difference in ing, the mean catches of Morone larvae spawning time of about 1 week between in the discharge and intake aims (Fig. 5) heated and unheated areas in 1976. indicated no apparent difference in the Lepomis larvae were still being captured duration of spawning^. = INTAKE ARM = DISCHARGE ARM INTAKE ARM 1.8- = = DISCHARGE ARM 1.6- ^''' -. ^ 1.2- t— £ l.O- S O'S S 0.6' 2 O.t 0,2 15 22 50 5 JULY AUGUST Fig. 4. —Mean catch of Lepomis larvae in the Fig. 5. —Mean catch of Morone larvae in the discharge and intake arms of Lake Sangchris discharge and intake arms of Lake Sangchris (1976). (1976). 628 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 o Qo was 0) Aug. 1981 Bergmann: Larval Fishes 629 eg in oo o . OO to Tt" 00 o o d ^* oiooTfr-tooovo^intM -^ —'-'tN'^ddc^'.-^dd -d •" <-« 00 . . .on CM • - • d d • CT) Oi 00 to ^ 0>—'OCoOC^^.—-^ r^ r^ 00 to 00 00 o oo d d ^ d> "O 3 t^ o o on OO 630 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 SUMMARY the Study of the Sea. Journal du Conseil 22:42-57. Copenhagen, Denmark. 1.— The most abundant larval fish 1976. HoGUE.J. J.. Jr.. R. Wallus. and L. K. Kav. wds gizzard shad, which constituted 89.4 Preliminary guide to the identification of lar\'al percent of the total catch. Lepomis and fishes in the Tennessee River. Technical Note B19. Tennessee Valley Authority. Division of Morone larvae accounted for 9.1 and 1.5 Forestry. Fisheries, and Wildlife Development. percent of the catch, respectively. Norris. TN. 67 p. Larimore. R. W., and A. Tranquilli. 1981. The 2. — Gizzard shad densities were J. Lake Sangchris project. Pages 279-289 m R. W. highest in coves and mouths of creeks Larimore and J. A. Tranquilli, eds.. The Lake from both the discharge and intake arms, Sangchris study: case histon,' of an Illinois cooling indicating the thermal effluent had no in- lake. Illinois Natural Histor>- Surrey Bulletin fluence on their spatial distribution. 32 (4). Marcy, Barton C, Jr. 1973. Vulnerability and 3. — For gfizzard shad and Morone survival of young Connecticut River fish larvae little difference was observed in the entrained at a nuclear power plant. Canada temporal appearance of larvae in the Fisheries Research Board Journal 30 (8): 1195-1203. discharge and intake arms. May. Edwin B.. and Charles R. Gasaway. 1967. 4.— Lepomis larvae were collected A preliminary key to the identification of lanal fishes of Oklahoma, with particular reference to earlier and were more abundant in the Canton Reservoir, including a selected in the intake discharge arm than arm. bibliography. Oklahoma Fishery Research Laboratory. Bulletin Number 5. 44 5. — The low number of gizzard shad p. Nelson, D. D., and R. A. Cole. 1975. The and Lepomis larvae found in deep water distribution and abundance of larval fishes along in the intake canal indicates that few lar- the western shore of Lake Erie at Monroe. vae were vulnerable to entrainment dur- Michigan. Technical Report No. 32.4. Institute ing the daytime. of Water Research. Michigan State University. East Lansing, MI. 66 p. 6. —The vertical migration study in- Noble, Richard L. 1970. Evaluation of the Miller dicated that gizzard shad densities were high-speed sampler for sampling vellow perch and walleye frv. Canada Fisheries Research highest at the surface during daylight, Board Journal 27(6);1033-1044. while at night, densities were highest near Snedecor, George W.. and William G. Cochran. the bottom. 1967. Statistical methods. The Iowa State University Press. Ames. 593 p. REFERENCES CITED Tranquilli. J. A., R. Kocher. and J. M. Aron, W.. and S. Collard. 1969. A study of the McNuRNEY. 1981. Population dynamics of the influence of net speed on catch. Limnology and Lake Sangchris fishery. Pages 413-499 in R.W. 242-249. Oceanography 14(2): Larimore and J. A. Tranquilli. eds.. The Lake BoDOLA, A. 1966. Life history of the gizzard shad Sangchris study: case history of an Illinois cooling Dorosoma cepedianum (XeSueur). in western lake. Illinois Natural History Survey Bulletin 32 Lake Erie. U.S. Fish and WildHfe Service Fishery (4). Bulletin 65{2):391-425. Werner, R. G. 1967. Iniralacustrine movements of Bridger. J. P. 1956. On day and night variation in bluegill fry in Crane Lake. Indiana. .American catches of fish larvae. International Council for Fisheries Society Transactions 96(4);416-420. Impingement and Entrainment of Fishes at Kincaid Generating Station Wesley Porak and John A. Tranquilli ABSTRACT relatively low total estimate of 2.2 million eggs lost during the spawning season. Giz- 1-year study was conducted to assess A zard shad (85.61 percent), MoTone spp. the effects of Kincaid Generating Station's (4.03 percent), and Lepomis spp. (0.66 cooling-water intake system on the Lake percent) accounted for most of the larval Sangchris fishery. The entrainment of fish entrained. The entrainment of larval fish eggs and larvae was investigated dur- fishes during 1976 reduced the gizzard ing the period of reproductive activity, shad population by 4.74-5.48 percent and the impingement of juvenile and and the Lepomis population by 0.33-0.59 adult fishes on the traveling screens was percent. The numerical standing crop of the year. The number studied throughout unidentified Morone larvae, considered to of fishes impinged and and/or biomass be mostly yellow bass, was reduced 15.29 entrained at Kincaid Generating Station percent by entrainment. were compared to standing crops and in During 1976 impingement and entrain- some cases also to fecundities and natural Kincaid Generating Station's mortality rates to determine the overall ment at cooling-water intake system caused only effect of the intake system on the fish reductions in numbers of community. relatively minor a few overabundant and/or undesirable From December 1976 through March species, and consequently was found to 1977, 94.16 percent of the estimated total have no adverse impact on either the in- impingement occurred. Gizzard shad dividual populations of those species or (83.38 percent) and yellow bass (14.26 the sport fishery. Entrainment was af- percent) accounted for 97.64 percent of fected by a 26-percent reduction in the estimated 158,853 fish impinged on cooling-water use by the utility during the the screens. Small tlshes were the most 1976 spawning season. Taking this factor vulnerable to impingement; 93.8 percent into consideration did not change our of all the fish collected were less than 200 evaluation of the potential impact of the mm in total length. Mean condition fac- intake system on the fishery. tors of gizzard shad and yellow bass col- lected from the intake area by elec- trofishing were significantly higher INTRODUCTION (P <0.01) than condition factors of these A 1-year study was conducted to assess species collected from the traveling the effects of the Kincaid Generating Sta- screens, indicating that stressed fishes tion's intake system upon the fish popula- were especially vulnerable to impinge- tion of Lake Sangchris. Entrained fish ment. Numerically, impingement reduc eggs, larvae, and small juveniles were col- ed the standing crop of gizzard shad and lected quantitatively during the period of yellow bass by 1.82 and 7.86 percent, reproductive activity. Larger fishes were respectively. collected from the traveling screens Only 218 fish eggs were collected during throughout the year to determine the entrainment sampling, accounting for a total number and biomass lost by im- pingement. The number and biom2iss of Wesley Porak is with Tennessee Technological fishes impinged and entrained at the Kin- University, Cookeville. and Dr. John A. Tranquilli caid Generating Station were used in con- is an Associate Aquatic Biologist in the Section of Aquatic Biology, Illinois Natural History Survey. junction with estimates of standing crops, fecundities, natural mortality rates This chapter submitted in Nov. 1977. and 631 632 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 (n I Aug. 1981 Porak&Tranquilu: Impingement and Entrainment of Fishes 633 ffl (3 p ore 0) T3 a n o LU q: to O LU D. Z Q- LLJ E — i-s: — z: > < ZD I- ID < CC 3 Q. < Q. 3: 1— LU _) CO z) a: O LU f — < O ID O O 634 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 to determine the overall effect of the in- study period, and usually only one or two take system upon the fish community of were in operation at any given time. In Lake Sangchris. addition, three service water pumps are The impingement and entrainment present to provide water for noncooling sampling schedule was developed in purposes, and their use is contingent cooperation with Commonwealth Edison upon the number of generating units in Company (CeCo) and represents the level operation. Each service water pump has a of sampling effort requested by the utility maximum capacity of 24,000 gpm (90.8 and agreed to by the Illinois Natural m'/min). History Survey. The sampling progfram was presented to the U.S. Environmental IMPINGEMENT Protection Agency by CeCo; however, no MATERIALS AND METHODS comments were received from the USEPA. One 24-hour sample was collected each week from the traveling screens at the in- DESCRIPTION OF THE take of the power plant from 10 March STUDY AREA 1976 through 13 February 1977. Collec- tions were made twice each week from One intake structure, with six intake bays 21 February through 4 April 1977, when well, ser- opening into a common pump large numbers of fish were being imping- generating units the Kincaid vices both at ed. Two final samples were taken 11 Generating Station (Fig. 1). Vertical April and 19 April 1977. racks spaced 2.5 inches cm) trash (6.35 Power plant personnel operated the apart prevent large debris from entering traveling screens, emptied the trash the power plant. A skimmer wall directly basket, and logged the time of operation behind the trash racks extends approx- on the day preceeding each sampling imately 6 below the water's surface m date. The traveling screens were again (Fig. 2). Behind the skimmer wall are six operated 24 hours later in the presence of traveling screens, consisting of panels of a biologist, who collected the fish from heavy steel mesh with 0.375-inch (0.95-cm) the trash basket. Since the spray nozzles square openings, that further obstruct may not always remove every fish from the passage of fish and debris through the the traveling screens, the screens were intake bays. When the vertically revolv- observed as they were operated, and any ing screens are operated, fish and debris remaining fish were collected and includ- are removed by water sprayed from high- ed in the sample. Freezing conditions pressure nozzles and are washed down a prohibited use of the permanent trash sluiceway into a permanent trash basket basket for collecting fish on several winter lined with 0.25-inch (0.64-cm) mesh sampling dates. When the trash basket hardware cloth. The trash basket outside was inoperable, a portable basket con- the cribhouse can be emptied from the structed of 0.25-inch (0.64-cm) mesh bottom for removal of its contents. Fish hardware cloth was used to collect fish. and debris are removed and transported The portable basket was also used from to a disposal area. mid-January to 8 February 1977 when the A once-through cooling system is used by traveling screens were run continuously to the Kincaid Generating Station at Lake alleviate icing problems. Sangchris. Circulating water pumps Decayed fish that obviously had been withdraw water from the intake canal at dead for longer than 24 hours were ex- the rate of 160,000 gpm (605.6 mVmin) cluded from the impingement sample. per pump for use as cooling water (Fig. I Each impinged fish was weighed and and 2). The number of pumps used measured, and its condition was recorded depends upon the amount of cooling if it was unusual. When large numbers of water needed. Only three of the four cir- gizzard shad (Dorosoma cepedianum) and culating pumps were used during the yellow bass {Morone missisappiensis) were J Aug. 1981 PoRAK &Tranquilli: Impingement and Entrainment of Fishes 635 collected, subsamples were measured to 1976 through March 1977. Fourteen obtaih a length frequency distribution and species representing six families were col- a group weight. For comparison with lected in the samples (Table 2). Gizzard fishes captured from the intake area by shad (78.62 percent) and yellow bass electrofishing, a subsample of 25 fish of (19.36 percent) constituted 97.98 percent the same relative size (gizzard shad of the total fish in the samples. The 160-200 mm and yellow bass 100-140 mm percentages of other fishes collected from in total length) and 'of both sexes was the intake screens were bluegill, Lepomis selected from the total impingement sam- macrochirus, 0.89 percent; white bass, ple for the calculation of condition fac- Morone chrysops, 0.34 percent; channel tors. The coefficient of condition (K) was catfish, Ictalurus punctatus, 0.23 percent; calculated according to the formula K = black bullhead, Ictalurus melas, 0.19 W X lO'/L', where W is the weight in percent; and green sunfish, Lepomis grams and L is the total length in cyanellus, 0.16 percent. White crappie, millimeters (Carlander 1969). Pomoxis annularis; yellow bullhead, Ic- Velocity profiles (measured with a talurus natalis; largemouth bass, General Oceanics flowmeter, model Micropterus salmoides; freshwater drum, 2035) and samples for the measurement Aplodinotus grunniens; flathead catfish, of water-quality parameters (pH, con- Pylodictis olivaris; carp, Cyprinus carpio; ductivity, dissolved oxygen, and and golden shiner, Notemigonus temperature) were taken through stop- crysoleucas, comprised the remaining log grates (Fig. 2) in front of the traveling 0.21 percent of the total number of fish screens. collected. The volume of condenser cooling water RESULTS AND DISCUSSION used during each 24-hour sampling A total of 30,222 fish that weighed 534.3 period from March 1976 through April kg (1,176.9 lb) were collected in 63 1977 was used to calculate monthly fish samples washed from the traveling impingement rates per unit volume of screens from 10 March 1976 through 19 water. Between 11.9 and 30.1 percent of April 1977 (Table 1). Of all fish col- the total condenser cooling water used by lected, 94.85 percent were impinged dur- the station each month was sampled for ing the 4-month period from December fish impingement (Table 3). Since the Table 1, —Total numbers, weights in grams, and monthly percentages of total numbers and weights of fish impinged on traveling screens at the Kincaid Generating Station from March 1976 through 19 April 1977 Year 636 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Oa g a (0 •oa at c a E a) ' Aug. 1981 Porak&Tranquilli: Impingement and Entrainment of Fishes 637 V V r^ r* iD o O (£ f o 1^ ai on o .— o o in CM r* I— o oO oO 00 in tn oo ^ o o ^ (£ lO m ^ .-' (N — tN on CM r- o 638 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 E E E Q. E CO 1^ ^ en a. E o> w O <" £ CO <£> Sen o '" &§ 1° to g > oCO s: c n ._ a E S " (0 ISh O CD » > m Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 639 variability in cooling water use by the sta- weighed 2,309.9 kg were impinged by the tion affected the rate of fish impinge- power plant (Table 4). Thus, 1.82 per- ment, the level of plant operation was ac- cent of the lake area (15.9 of 876 ha) counted for in the projections. The would be required to produce the number of fish collected per month was number of impinged gizzard shad. divided by the amount of condenser cool- However, only 0.96 percent of the lake ing water sampled per month to deter- area (8.4 ha) would produce the biomass mine monthly impingement rates. For all of impinged shad. The difference fish species, the highest impingement estimated by biomass and number in- rates occurred during the winter and ear- dicates that the average size of impinged ly spring with a peak of 3,800 fish per gizzard shad was smaller than the average billion gallons (0.001 fish/m') of cooling size of all gizzard shad present in the lake. water in February 1977. Gizzard shad Gizzard shad, the major forage fish in 95.9 percent of the total constituted Lake Sangchris, are overabundant, con- of fish collected from December number stituting 76.3 percent of the total biomass 1976 through February 1977 (Table 2). (Tranquilli et al. 1981). Although pro- total of gizzard shad and The combined viding excellent forage when small, they yellow bass constituted 99.8 percent of quickly grow out of that size category, the fish collected in March 1977 and 95.4 and the adults are considered rough fish percent in 1976. Very few fish March that compete with sport fishes for food on the intake screens dur- were impinged and space. Since a part of any sport ing early fall. All monthly summer and fishery management plan for Lake impingement rates from through June Sangchris should include a recommenda- October 1976 were less than 20 fish per tion to reduce the gfizzard shad popula- billion gallons x 10"? -fish/m') cool- (5 of tion drastically, the loss of shad through ing water (Table 3). impingement should not be considered The monthly impingement rate the and detrimental to the overall fishery. volume of water used by the Kincaid Generating Station were used to estimate The total number of yellow hass imping- the total number and total weight of each ed during this study was estimated at species impinged per month. An 22,648 fish, weighing 567.2 kg (Table 4). estimated 158,853 fish that weighed The average standing crop of yellow bass 3,062.9 kg (6,752.4 lb) were impinged on in Lake Sangchris was determined to be the traveling screens from March 1976 9.2 kg/ha, or 329 fish per hectare (Tran- quilli et al. through 19 April 1977 (Table 4). 1981). Thus, the yellow bass that were Only yellow bass and gizzard shad were impinged on the traveling screen accounted impinged in sufficient numbers to have a for 7.86 percent by potential effect on the Lake Sangchris number and 7.04 percent by weight of the standing crop of yellow bass in fishery. Since all impinged fish collected Lake from the intake trash basket are disposed Sangchris. To produce this number of yellow bass requires 68.8 ha of the of, 100-percent mortality was assumed lake for the purpose of evaluation. area, but production of this weight re- quires only 61.7 ha. In six surveys Tranquilli et al. (1981) determined the average standing crop of Yellow bass do not reach sizes of interest gizzard shad in Lake Sangchris to be to most Lake Sangchris anglers and have 275.3 kg/ha, or 8,309 fish per hectare. almost no economic or sport fish value. The total surface area of Lake Sangchris They feed almost entirely on zooplankton is 876 ha. During the study period an and, in littoral areas, compete heavily estimated 132,457 gizzard shad that with bluegills and young-of-the-year 640 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 ^ si I Q < cn o ora c o 0) Q. E o Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 641 to in « « s s s § V V V V -—in ^ c^ o 'I -^ N ^ t£> CO ^ 2 a. < -I CO 00 ^ r* • oO • oo • • 00 00 • • • OO J3 • • • • lO OO • • ^ CJ) - ...... • • • to • ' • ' • : 00 CTi < . 642 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 largemouth bass for this limited food velocities were not high enough to im- resource. Although yellow bass in Lake pinge all fish in the vicinity of the traveling Sangchris are relatively small, they are screens, because congregations of fish not preferred forage for other sport were often observed swimming at the sur- fishes. Thus, these yellow bass could best face on the pump side of the skimmer be described as undesirable rough fish. wall. Since the Lake Sangchris fishery would Smcdl fishes were most vulnerable to im- probably be more productive of sport pingement. The average weight of imping- fishes if the yellow bass population were ed fish was only 19 g (Table 4). One reduced or eliminated, the observed mor- largemouth bass, one carp, and several tality of yellow bass by impingement is, white crappies and white bass longer than like that of gizzard shad, not considered 300 mm were found in the impingement detrimental to the Lake Sangchris samples, but 93.8 percent of all fishes col- fishery lected from the iiitake screens were less Velocities of water currents were than 200 mm in total length. Latvaitus measured in front of the six intake screens (1976) attributed the large number of of the Kincaid Generating Station under small fish impinged at the Quad Cities varying modes of operation when one to Nuclear Plant on the Mississippi River to three circulating water pumps were run- the inability of smaller individuals to ning. A maximum velocity of 0.34 m/sec- escape the turbulence and velocity of the ond (1.12 ft/second) was recorded when intake currents. Length frequency three pumps were running (Table 5). distributions for gizzard shad, yellow Water velocities were typically very low bass, and 12 additional fish species im- from the surface down to the 5-m depth pinged at the Kincaid Generating Station due to the presence of the skimmer wall. indicated that the majority were young- The highest velocities were recorded at of-the-year individuals (Fig. 3). depths of 6-8 m. At 9 m a concrete brace On impingement and entrainment partially blocked the flow (Fig. 2), but sampling dates, water temperature, from 10 to n.5 m the velocities were dissolved oxygen, and conductivity were again relatively high. From our observa- measured in profiles (1-m intervals) at the tions of the eddies between the skimmer intake structure. The mean dissolved ox- wall and the traveling screens and the ygen value ranged from 6.6 to 12.2 ppm, fluctuating values that we observed on while the mean specific conductance the flowmieter, we concluded that the (standardized to 25°C) ranged from 549 flow of water through the intake structure to 657 Mniho/cm. Mean hydrogen ion was turbulent. However, the intake concentration (pH) measured at the sur- Table 5. —Velocities (cm/sec) measured in front of the intal GIZZARD SHAD 20- = 23.760 10 S 20 YELLOW BASS N = 5.850 10 c_> en I I I I I I I I I 1 I I I I I I I I 100 150 200 250 20- 12 ADDITIONAL SPECIES N = 613 10- I I I I I I I ^r-r I I I I I I I I I I 100 200 300 400 TOTAL LENGTH (mm) Fig. 3 — Length-frequency distribution of weekly samples of gizzard shad, yellow bass, and 12 additional fish species impinged on the intake screens- of Kincaid Generating Station from March 1976 to April 1977. 644 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 mobility of fish during cold weather may lower (P<0.01) than the mean K value of not allow them to avoid the intake screens fish from the intake area for all months in or to free themselves if they are impinged. which comparisons could be made. These A natural winter die-off of fishes could data indicate that the fish most also affect the rate of impingement. Mass vulnerable to entrainment by the power mortality of gizzard shad was observed plant are individuals in poor body condi- during the winter in New Mexico, when tion, weaker individuals that would be water temperatures fell below S.S^C selected by natural predators in the lake (Jester & Jensen 1972). itself. The higher impingement rates observed During the springs of 1976 and 1977, a during the winters and early springs of large number of impinged fish were in- 1976 and 1977 may also have been fested with aquatic fungi. Bennett (1970) associated with the greater use of cooling reported that condition to be associated water by the Kincaid Generating Station with reduced resistance to infection as a at those times and by the attraction of result of winter conditions and rising fish the intake area the water temperatures. to by warm water recirculated into the intake canal by deic- Emaciated fish were frequendy found in ing pipes. impingement samples. A comparison of coefficients of condition (K) was made between gizzard shad impinged at Kin- ENTRAINMENT caid Generating Station and samples col- lected from the intake area of Lake MATERIALS AND METHODS Sangchris by electrofishing during From 25 March through 15 April 1976, March, May, and November 1976. A entrainment samples were taken froni a similar comparison was made for yellow boat at the intake canal of the Kincaid bass during March (Table 6). Although Generating Station through a 1.5-inch fish from the two locations were of the (3.81 -cm) diameter plastic hose and a cen- same relative size, the samples collected trifugal pump. Intake water was pumped from the lake consisted entirely of males, through a No. 3 mesh (0.333-mm) while the samples from the impingement plankton net suspended partially in the collection were composed of fish of both water from the boat. Nine 45-minute sexes. Since ovaries usually are larger pump samples were taken over a 12-hour than testes, a larger mean condition value period at an average rate of 54 gpm would be expected for the fish from the (0.204 m'/min). Three depths were in- impingement sample as a result of the dividually sampled at three stations (one bias due to sex. In addition, Larimore located in front of each of the three ver- (1952) showed that when temperatures tical trash racks) in random order. were below 2I"C, as in this comparison, From 22 April to 12 August 1976, fish gained weight immediately after 24-hour entrainment samples were taken death for a period of more than 24 hours twice each week through the stop-log due to absorption of water through the grates on top of the intake structure (Fig. skin. In spite of such bias, the mean con- 2). Samples were taken at weekly intervals dition of impinged fish was significantly from 12 August through 4 October 1976. Table 6. —Comparison of the mean coeffici ent of condition (K) between fish captured by electrofishing in the intake area of Lake Sangchris and fish impinged at Kincaid Generating Station in 1976. Aug. 1981 PoRAK & Tranquilu: Impingement and EIntrainment of Fishes 645 UJLU 646 IixiNois Natural History Survey Bulletin Vol. 32, Art. 4 Collecting an entrainment sample from the intake canal of the Kincaid Generating Station. May, when a second pump was obtained. samples were used to determine the Throughout the remainder of the study volumes of unmetered samples. period, two depths were sampled From June through October 1976, simultaneously from the same intake bay. organisms were collected from the An intake bay directly in front of one or plankton nets at approximately 4-hour between two operating circulating water intervals to investigate diurnal differences pumps was chosen. The depths sampled in entrainment rates of fish eggs and lar- at the intake were (1) between the bottom vae. That procedure also reduced the of the skimmer wall and a horizontal con- amount of damage to larval fish ex- crete ledge at approximately 8 m and (2) perienced during less frequent collecting between the concrete ledge and the bot- prior to June. of the intake structure at approx- tom All samples were preserved in 5-percent imately 12.5 m (Fig. 2 and 4). formalin. Samples were returned to the The total volume of individual piunp laboratory, where all fish eggs and larvae samples was measured on one pump with were sorted from other organisms cap- a Rockwell turbometer (model tured by the plankton net. Fish eggs were W-160DR) connected between the pump counted but not identified. Larval fishes and the plankton net (Fig. 4). Average were counted and identified to the lowest pumping rates calculated from metered possible taxonomic level, using keys and Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 647 literature by Fish (1932), Mansueti & tween the numbers of fish eggs collected Hardy (1967), May & Gasaway (1967), at the two depths. and Hogue et al. (1976). Meyer (1970), To estimate the total number of fish eggs standardized Ichthyoplankton data were entrained by the Kincaid Generating Sta- into catch per unit effort and expressed as tion, the mean density of eggs was (or larvae) per 10 m' number of fish eggs multiplied by the total flow of water of water. through the plant during the major profiles and water parameters Velocity period of egg entrainment from 31 May through the stop-log were measured through 12 August. An estimated 2.2 front of the traveling screens. grates in million eggs were entrained during the were obtained from power Pump data 1976 spawning season. Since so few eggs plant personnel. were collected, a rigorous evaluation of entrainment was RESULTS AND DISCUSSION the impact of fish-egg not made. However, the estimate of 2.2 total of 218 fish eggs was collected dur- A million entrained eggs appears minimal the study period. Most of the eggs ing when considering the prolific nature of (99.5 percent) were collected from 31 most fish species. For example, data cited through 12 August (Fig. 5). The May by Carlander (1969) showed fecundities greatest number of fish eggs found in 1 for age II gizzard shad ranging from day was collected on 1 July at a density of 211,378 to 543,912 eggs per female. Low fish eggs/ 10 m'. 0.895 fish-egg entrainment rates might have Fish eggs were collected in very low been expected, because all species of fish numbers at depths of 8 m and 12.5 m in Lake Sangchris, with the exception of during the study period. A t test indicated freshwater drum, have demersal or no significant differences (P< 0.05) be- semibouyant adhesive eggs. 0.9n TOTAL NUMBER OF EGGS = 218 0.5- 0,4- oo S 0.3-1 S 0.2H UJ ca 0.1- 22 1 29 5 I 15 26 3 10 -APRIL- AUGUST- Fig. 5.— Density of fish eggs collected at the intake of Kincaid Generating Station during 24-hour pump samples taken from 15 April through 30 August 1976. 648 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 7. —Total numbers, mean densities (larvae/10 m'), and percentages of fish larvae collected during 24-hour pump samples at the intake of the Kincaid Generating Station. 15 April through 7 September 1976. Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 649 entrainment samples, constituted 85.6 fishes may survive after passing through percent of the larvae collected (Table 7). condensers, Marcy (1974) observed that The percentage of other larval fishes in the percentage of survival may be very the samples was Morone, 4.03 percent; low. Consequently, to evaluate the Lepomis, 0.66 percent; and freshvi^ater "worst-case" effect of larval fish drum, 0.09 percent. Three flathead entrainment by the Kincaid Generating catfish, two channel catfish, and one Station, we assumed that all were killed. unidentified cyprinid were also collected. The very low numbers of freshwater Due to mechanical damage caused by the drum, fiathead catfish, channel catfish, sampling equipment, 9.6 percent of the and the unidentified cyprinid collected in larvae were decapitated or mutilated and the samples during the study period could not be identified; however, we indicated that entrainment of those assumed that unidentified larvae species was negligible. Therefore, an occurred in the same proportions as those assessment of the impact of larval fish identified in the collection. entrainment was only made for gizzard shad. Morone, and Lepomis. During the spawning season, fish larvae were collected regularly from both Use of condenser cooling water at the depths sampled at the intake structure. Kincaid Generating Station during the Mean densities of fish larvae were 1976 spawning season was unusually low. significantly higher {t test: P< 0.05) at 8 Flow rates from 15 March through 30 m than at 12.5 m. A greater abundance August 1976 were compared to flow rates of fish larvae at 8 m may have been during the same time period in 1974, associated with the higher intake 1975, and 1977. The mean flow during velocities observed between the skimmer the "spawning season" for those 3 years wall (6 m) and a horizontal concrete was approximately 26 percent greater ledge at 9 m (Table 5). than the flow during the 1976 season, partially because of a nonscheduled Diurnal differences in entrainment outage at the Kincaid Generating Station rates of larval gizzard shad were from the middle of Augfust through the compared on 27 May and 10 June, when middle of September. Still, flow rates samples were collected at 4-hour intervals were lower during the other months as for 24 hours. Although densities were well. Since the amount of cooling water highest during hours of darkness, a one- used affects the rate of ichthyoplankton way analysis of variance indicated that no entrainment, 1976 ichthyoplankton en- significant diurnal differences (P<0.05) trainment results should be considered existed during those two series. Higher lower than normal. gizzard shad entrainment rates during the night may have been associated with A total of 18,594 gizzard shad larvae was diurnal differences in the vertical collected during the study period (Table distribution of larval gizzard shad. 7). Larval gizzard shad densities were Bergmann (1981) found few gizzard shad highest from 17 May through 10 June larvae in deep water during daylight and (Fig. 7), when mean water temperatures high densities near the botrom of the lake ranged from 18.4" to 24.2"'C. A peak den- at night. He suggested that the period of sity of 39.14 gizzard shad larvae/10 m' highest entrainment would be at night, was observed on 27 May. since cooling water is drawn from 6 m An estimated 214.6 x 10' gizzard shad below the at Kincaid Generating surface larvae were entrained from 22 April Station. through 21 July 1976 (Table 8). The Fish larvae that pass through number was calculated from entrainment condensers may suffer direct or latent rates and cooling water use rates between mortality from temperature shock, consecutive sampling dates. The impact prolonged exposure to elevated of gizzard shad entrainment was assessed temperatures, mechanical effects, and by companng that estimate with the stand- chemical effects. Although some larval ing crop of larval gizzard shad in Lake 650 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 = GIZZARD SHAD = MORONE SPP «= FRESHWATER DRUM = LEPOMIS SPP APRIL- AUGUST'^SEPT. Fig. 7. — Density of major taxa of larval fishes collected at the intal Sangchris during the same period (deter- The impact of larval gizzard shad en- mined from data presented in Bergmann trainment was also viewed from the 1981). For that comparison , we assumed aspect of recruitment. Ricker (1975) that the standing crop of gizzard shad lar- postulated that a stable population re- vae found in the intake and discharge quires two adults to replace themselves arms of Lake Sangchris was repre- via reproduction during their spawning sentative of densities of larval shad in the en- lifetime. From data cited by Carlander tire lake. The total standing crop of lar- (1969), the weighted mean fecundity of val gizzard shad in Lake Sangchris during gizzard shad ranging in total length from the period of entrainment sampling was 282 to 381 mm was determined to be estimated to be 4,523.1 x 10° fish. This 287,679 eggs per female. To maintain estimate was determined by multiplying population stability, one egg would have the mean daily density of larvae to survive during each of the 2 expected (1,329/m') by the total volume of the spawning years, or a survival rate of 3.48 ~ lake at normal pool (37.4 x 10 m ) and X 10 . Assuming equal rates of multiplying the product by the days in natural mortality for development of eggs the study period (91). The estimated to larvae and larvae to adults, a survival number entrained thus represented 4.74 rate of 1.86 x 10~' (0.19 percent) was percent of the estimated standing crop of calculated. Using that rate, the 214.605 x gizzard shad larvae in Lake Sangchris 10° gizzard shad larvae entrained, repre- during 1976. sent 399.165 X 10' potential adults lost to Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 651 f 652 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 the population. The average standing 84 percent of the total standing crop of crop of gizzard shad in Lake Sangchris Lepomis in Lake Sangchris (Tranquilli et was determined to be 8,309 fish per hec- al. 1981). Using that figure and data tare (Tranquilli et al. 1981). Thus, from cited in Carlander (1977), the weighted the aspect of recruitment, the total loss of mean fecundity of bluegills and green larval shad in the 876-ha Lake Sangchris sunfish ranging in total length from 102 system represents 5.48 percent of the mm to 177 mm was calculated to be numerical standing crop of adults, a 16,361 eggs per female. To maintain a value slightly higher than the estimated stable population, a survival rate of 4.1 loss of 4.74 percent obtained by calcula- X 10 ~* would be required for two eggs to tion from the estimated standing crop of survive to adults over 3 years of expected larval fish in Lake Sangchris. Such a loss spawning activity. Assuming equal rates appears negligible in light of the abun- of natural mortality for the development dance of this species in the lake. of eggs to larvae and larvae to adults, the estimated entrainment of 1,716,100 Only two members of the genus Lepomis Lepom,is larvae would represent 10,983 are present in Lake Sangchris: bluegills potential adults lost to the population at (the more abundant species) and green ~' sunfish. Entrained Lepomis larvae were a larval survival rate of 6.4 x 10 (0.64 percent). This estimate represents a loss not identified to species because of the of 12.5 fish/ha in Lake Sangchris or 0.59 difficulty in separating them. percent of the total standing crop of A total of 143 Lepomis larvae was col- 2,114 Lepomis /ha found by Tranquilli lected at the intake from 10 June through et al. (1981). 30 August, when mean water temperatures ranged from 23.5° to The two species of Percichthyidae in yellow 28.5''C. Entrainment rates of Lepomis Lake Sangchris are white bass and larvae were low throughout that period bass. From 15 April through 10 June total larvae with a peak density of only 0.592 lar- 1976, a of 876 percichthyid were collected at the intake, but no vae/10 m' of water on 22 July (Fig. 7). means have been devised for differentia- The effect of Icirvcil Lepomis entrainment tion between larvae of these species was assessed by comparing entrainment (Hogue et al. 1976). The highest entrain- data with Lepomis standing crop ment rates occurred from 22 April estimates determined from 27 May through 6 May, when mean water through 5 August, the last date temperatures ranged from 13.6" to Bergmann (1981) collected larval fishes. 18.0°C. A peak density of 6 185 Morone During that period, an estimated larvae/ 10 m' of water sampled was 1,707,100 Lepomis larvae were entrained observed on 26 April (Table 8). (Table 8). Assuming equal distribution of larvae throughout the lake, the estimated The estimate of 15,785,100 Morone lar- standing crop of Lepom.is larvae was vae entrained during 1976 was calculated calculated to be 520.31 x 10^ by multiply- from entrainment rates and cooling water ing the daily mean density of Lepomis use rates between consecutive sample larvae (0.188/m'), calculated from dates (Table 8). To evaluate the impact Bergmann's data (1981), by tne total of entrainment, that estimate was com- volume of Lake Sangchris at normal pool pared to numerical standing crop and multiplying the product by the days estimates o{ Morone larvae found in Lake in the study period (74). Thus, approx- Sangchris during the same period (deter- imately 0.33 percent of the estimated mined from data presented in Bergmann numerical standing crop of Lepomis lar- 1981). Assuming equal distribution of vae were entrained at the Kincaid larvae throughout the entire lake, the Generating Station. standing crop was calculated by multiply- The impact of Lepomis entrainment was ing the daily mean density of Morone lar- also evaluated from the aspect of recruit- vae (0.046/m') by the total lake volume ment. By number, bluegills constituted at normal pool and multiplying the pro- Aug. 1981 PORAK& Tranquilli: Impingement and Entrainment of Fishes 653 duct by the days in the study period (60). fishery. In addition, the impinged in- Thus, 15.29 percent of the estimated 103 dividuals were in significantly poorer million Morone larvae in Lake Sangchris body condition than those captured from during 1976 were entrained by the Kin- the intake area by electrofishing, in- caid Generating Station. dicating that stressed individuals were be- The impact of Morone entrainment was ing impinged selectively. not evaluated from the aspect of recruit- Entrainment of ichthyoplankton was ment because the fecundity of yellow bass primarily of gizzard shad, Morone, and of the size range present in Lake Lepomis. When compared with standing Sangchris was not known. Also, white crops of larval fishes in the lake at the bass have higher fecundities and reach a same time, 4.74 percent of the gizzard larger adult size than do yellow bass, and shad larvae in Lake Sangchris were en- the proportion of the two species as larvae trained during 1976. From the aspect of in the lake was not known. recruitment, the numerical loss in en- trained gizzard shad was very For purposes of evaluation, we assumed nearly the same at 5.48 percent of the 100 percent mortality for entrained fish numerical standing crop of adults. loss eggs and larvae. Unlike impinged fishes, The of that however, entrained organisms do not number of gizzard shad, the principal forage species, would not likely represent a complete loss of energy to the have an adverse impact either the ecosystem because they are recycled to on fishery or the individual the discharge canal and used by animals population, because the species is already overabundant, in other trophic levels. The seasonal ap- con- stituting 76.3 percent by weight of the pearance of entrained fish eggs and lar- total fish biomass (Tranquilli et al. vae may serve as a food resource and be 1981). partially responsible for the seasonal ag- Entrainment of Morone larvae Wcis esti- gregation of certain species of fishes in mated to have reduced the numerical stand- the discharge canal (Tranquilli et al. ing crop of white and yellow bass in Lake 1981). Sangchris by 15.29 percent. A loss of that magnitude would have a detrimental ef- Although our sampling schedule was not fect if it consisted entirely of white bass, a extensive, it provided useful estimates of major sport fish. Most of the Morone lar- the magnitude of fishes lost at the power vae, however, were believed to be yellow plant intake, especially in a closed lake bass, because standing crop surveys show- system where current population data ed that the ratio of juvenile and adult were available for direct comparison. yellow bass to white bass was 329:18/ha (Tranquilli et al. 1981). Since yellow bass ENVIRONMENTAL IMPACT are rough fish that compete with sport OF THE INTAKE SYSTEM fishes for food and space, a reduction in their population would likely be Although 14 species of fishes were im- con- sidered beneficial to the fishery. pinged on the traveling screens at Kincaid Annual mortality Generating Station, only gizzard shad of yellow bass at Kincaid Generating Station, including entrain- and yellow bass were captured in suffi- ment of 15.29 percent of the cient numbers to have a potential effect numerical standing crop of larvae and impingement on the fish population of the lake. A com- of 7.86 p)ercent of the juveniles parison of impingement losses of these and adults, would have a minimal effect either the species with their populations in Lake on species population or the fish community. Sangchris indicated that their numbers were reduced by 1.82 and 7.85 percent, During the 1976 spawning season, en- respectively, during a 415-day sampling trainment of bluegills and green sunfish period. Considering the abundance and reduced the larval Lepomis standing crop relative importance of these species in in the lake by 0.33 percent. Viewed from Lake Sangchris, the observed reductions the aspect of recruitment, entrainment would have no discernible impact on the reduced the numerical standing crop of 654 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Lepomis by 0.59 percent. The ratio of SUMMARY juvenile and adult bluegills to green sun- I . — The major period of fish im- fish in standing crop samples from coves pingement occurred from December 1976 was l,899:213/ha (Tranquilli et al. through March 1977, when 94.16 percent 1981). Although bluegills represent an of the estimated total impingement oc- important part of the sport fish harvest in curred. Lake Sangchris, their slow? growth and 2.— Gizzard shad constituted 83.38 stunted condition as a result of overabun- percent and yellow bass 14.26 percent of dance detract from their potential value. the estimated 158,853 fish impinged from Thus, the loss of Lepomis larvae by March 1976 to 19 April 1977. The re- entrainment had no adverse effect. maining 2.36 percent of the total fish im- pingement comprised 12 additional A discussion of the impact of impinge- species. ment and entrainment would be in- complete without considering the com- 3.— Small fishes were highly pensatory response of fish populations to vulnerable to impingement. The majority the predatory type of mortality induced of the impinged fish were young-of-the- by power plants. McFadden (1977) noted year individuals, and 93.8 percent of all that the agent of mortality, whether it be the fish collected were less than 200 mm predatory fish, fishermen, or power in total length. plants, is indifferent to the population. 4. — Gizzard shad and yellow bass col- population is reduced, the When the lected from the traveling screens at Kin- rate or reproductive rate of the survival caid Generating Station had significantly tends to increase; a remaining members lower {P< 0.01) mean body condition response is generated. compensating factors than individuals of the same also pointed out that when the McFadden species collected from the intake area by mortality takes a form similar to natural electrofishing, indicating that stressed predation, little harm results, because it fishes were being impinged selectively. is the kind of impact to which the population has adapted over millions of 5. — Numerically, impingement years of evolutionary experience. reduced the standing crop of gizzard shad by 1 . 82 percent and the standing crop of yellow bass by 7.86 percent. The reduc- In summary, on the basis of a 1 -year tions in the standing crops of these species monitoring study, it appears that the en- were considered to have no adverse effect trapment of fish eggs, larvae, juveniles, on the sport fishery of Lake Sangchris. and adults at the Kincaid Generating Sta- tion's cooling water intake system has 6. — A total of 218 fish eggs collected caused only relatively minor reductions in during entrainment sampling accounted numbers of a few overabundant or for a relatively low total estimate of 2.2 undesirable species, and consequently has million eggs lost by entrainment during caused no adverse effect on either the in- 1976. Since low numbers offish eggs were dividual populations of those species or collected, a rigorous evaluation of fish on the Lake Sangchris sport fishery. Even egg entrainment was not made. considering a 26-percent reduction in 7.— Gizzard shad (85.61 percent), plant cooling water flow during the 1976 Morone (4.03 percent), and Lepomis spawning season and a likely 26-percent (0.66 percent) accounted for most of the greater loss with normal flow, our evalua- larval fishes entrained at the Kincaid tion of the overall impact on the fishery Generating Station. The species composi- did not change. This study and that of tion of fish larvae damaged by the pumps Bergmann (1981) have demonstrated (9.6 percent), and consequently uniden- that the existing intake system is well tifiable, was assumed to be similar to that located and well designed and results in a of the identifiable fish larvae. minimal impact on the surrounding en- vironment. 8. —Statistical tests provided no Aug. 1981 PoRAK & Tranquilli: Impingement and Entrainment of Fishes 655 evidence of diurnal differences in en- Elephant Butte Lake. New Mexico State Univer- sity Agricultural Experiment Station Research trainment rates for gizzard shad larvae. Report 218. 56 p. 9. — Two methods of estimating the Larimore, R. W. 1952. Weight changes in fish impact of larval fish entrainment on after death. Journal of Wildlife Management numerical standing crops revealed that 16(2):131-I38. gfizzard shad and Lepomis populations Latvaitus. B. P. 1976. Impingement investigation. 125-168 in Operation environmental were reduced by 4.74-5.48 percent and Pages monitoring in the Mississippi River near Quad- 0.33-0.59 percent, respectively. Entrain- Cities Station February 1975 through January ment of Morone was estimated to have 1976. Nalco Environmental Sciences North- reduced the numerical standing crop of brook, IL. 15.29 D. Hardy. 1967. white bass and yellow bass larvae by Mansueti, a. J., and J. percent. Development of fishes of the Chesapeake Bay Region. An atlas of egg, larval, and juvenile 10. Impingement and entrainment — stages. Part I. University of Maryland. of fishes at Kincaid Generating Station Baltimore. 202 p. in relatively minor during 1976 resulted Marcy, B. C Jr. 1974. Vulnerability and survival reductions in numbers of a few overabun- of young Connecticut River fish entrained at a plant. Pages 281-288 m En- dant or undesirable species and caused no nuclear power trainment and intake screening. Proceedings of adverse effect on the sport fishery. the Second Entrainment and Intake Screening 11.— Our evaluation of the overall Workshop. Electric Power Research Institute, impact on the fishery was not changed by Palo Alto, CA. taking into consideration a 26-percent May, E. B., and C. R. Gasaway. 1967. A preliminary key to the identification of larval reduction in cooling water use by the fishes of Oklahoma, with particular reference to the spawning season. utility during 1976 Canton Reservoir, including a selected bibliography. Oklahoma Fisheries Research REFERENCES CITED Laboratory Bulletin 5. 42 p. McConnell, G. R. 1975. Fishes section. Pages Bennett, G. W. 1970. Management of lakes and 80-102 in Studies on the effects of the Havana ponds. Van Nostrand Reinhold Co.. New York. Power Station on the ecological balance of the 375 p. River 1974 to 1975. Wapora. Inc., Bergmann, H. 1981. Distribution of larval fishes in Illinois Lake Sangchris (1976). Pages 615-630 in R. W. Charleston, IL. Tranquilli, eds.. The Lake T. 1977. argument supporting Larimore and J. A. McFadden, J. An Sangchris study: case history of an Illinois cooling reality of compensation in fish populations and lake. Illinois Natural History Survey Bulletin a plea to let them exercise it. Pages 153-183 m W. 32(4). Van Winkle, ed.. Proceedings of the Con- Carlander, K. D. 1969. Handbook of freshwater ference on Assessing the Effects of Power- Plant- fishery biology. Vol. 1. Iowa State University Induced Mortality on Fish Populations. Press, Ames. 752 p. Pergamon Press. New York. fishery . 1977. Handbook of freshwater Meyer, F. A. 1970. Development of some larval 2. Iowa State University Press, biology. Vol. centrarchids. Progressive Fish Culturist Ames. 431 p. 32:130-136. Fish, M. P. 1932. Contributions to the early life RiCKER, W. E.-1975. Computation and interpre- histories of sixty-two species of fishes from Lake tation of biological statistics of fish populations. Erie and its tributary waters. U. S. Bureau of Canada Fisheries Research Board Bulletin 191. Fisheries Bulletin 47:293-398. 382 p. K. Kav. 1976. ; HoGUE, R. Wallus, and L. R. Kocher, and M. J.j, Jr.. Tranquilli, J. A., J. Preliminary guide to the identification of larval McNuRNEY. 1981. Population dynamics of the I fishes in the Tennessee River. Tennessee Valley Lake Sangchris fishery. Pages 413-499 in R. W. j Authority, Norris, TN. 67 p. Larimore and A. Tranquilli. eds.. The Lake 1 J. L. Jensen. 1972. Life Sangchris study: case history of an Illinois cooling \ Jester, D. B.. and B. Survey Bulletin history and ecology of gizzard shad, Dorosoma lake. Illinois Natural History I to 32(4). I cepedianum (Le Sueur) with reference Waterfowl Studies at Lake Sangchris, 1973-1977 Glen C. Sanderson and William L. Anderson ABSTRACT were much more abundant on the heated water in November, slightly more con- The highest single count of waterfowl on centrated on the unheated water in Lake Sangchris was always in November March, equally numerous on both areas when counts were made in that month. in October, and were virtually absent However, mean monthly averages of total during the other months. Mergansers and waterfowl increased from less than 8,000 goldeneyes were present in low concentra- in October to less than 64,000 in tions from December through March and November and to 72,000 in December were more abundant on the heated water and then declined to approximately except in March, when no difference was 27,000 in January, less than 12,000 in evident. Canada geese were present in February, and about 6,000 in March. relatively low concentrations in all Mallards constituted from approximately months; their numbers were more concen- 50 percent of the total population in Oc- trated on the heated water in December tober to more than 95 percent in and on the unheated water in March but December. Other species that comprised showed no differences in other months. 10 percent or more of the population in one or more months were wigeons in Oc- From 0.2 to 0.4 percent of the maximum tober, Canada geese in February and number of waterfowl present at any one March, and coots in October. time was killed each fall by colliding with The chronology of abundance of the transmission lines at Lake Sangchris. Blue-winged teals were the mallards at Lake Sangchris and in the Il- most to collisions. linois River valley exhibited similar pat- vulnerable terns, but the fall buildup was 1-2 weeks Mean weights of ducks bagged at later at Sangchris, which is about 100 km Sangchris were within the range reported southeast of the Illinois Valley. In spring, for each species; however, the mean relatively fewer mallards stopped at weights of adult male and female Sangchris. mallards and adult female lesser scaups Mallards were found in equal concen- at Sangchris were heavier than a large trations on the unheated and heated series of mean weights reported in the water in October, in higher concentra- literature. At the same time, mean tions on the heated water from November weights of juvenile male and female through January, in equal numbers in mallards, wigeons, and lesser scaups; of February, and in higher concentrations adult male and female wigeons; and of on the unheated water in March. Gad- adult male lesser scaups were lower at walls, shovelers, and both species of teals Sangchris than a large series of mean were more abundant on the unheated weights reported in the literature. water in October and March, had similar Nearly 60 percent of the gizzards and concentrations in November, and were proventriculi of waterfowl shot at Lake virtually absent in other months. Coots Sangchris contained ingested slag. Studies with game farm mallards fed Dr. Glen C. Sanderson is a Wildlife Specialist diets of corn, corn plus slag, commercial and Head of the Section of Wildlife Research, Illinois Natural History Survey, and William L. maintenance chow, and chow plus slag Anderson is with the Illinois Department of indicate that slag possibly has adverse ef- Conservation, Llrbana. Illinois. fects on body weight and packed cell This chapter subinitted in Sept. 1978. volume of the blood. However, all ducks 656 Aug. 1981 Sanderson & Anderson: Waterfowl 657 dosed experimentally with slag survived the 8 -week experiment. Water areas heavily used by waterfowl at Lake Sangchris may receive as much as 65 kg of nitrogen and 36 kg of phosphorus per hectare in one season. INTRODUCTION The preference that waterfowl frequently exhibit for lakes used by power plants for cooling purposes is viewed with a mixture of pleasure and concern. Waterfowl thrill and delight thousands of people who visit cooling lakes and nearby areas, and the recreational opportunities provided in the form of waterfowl hunting are no less important. The concern of waterfowl biologists regarding the waterfowl at such lakes, and thus the reason for these studies, revolves around these questions: (1) Are the behavior and migration of the birds being altered? (2) Does the heated Fig. 1. — Locations of Lake Sangclnris and water adversely affect forage organisms? the illinois River valley. (3) Do the large transmission lines ema- nating from the power plants present in 1963-1966 by damming Clear Creek, consists of three long, relatively narrow hazards to flying birds? (4) Are birds that ingest slag at coal-fired plants adversely arms that extend southward for a distance of 8-11 km from the (Fig. affected? (5) Do the birds add large dam 2). For purposes of this study, the lake amounts of nutrients to the lakes? (6) Are was segmented into four areas, hereafter epidemics of botulism, duck plague, and other diseases increased? All of these con- referred to as the discharge arm (250 ha), area ha), intake arm ha), cerns except the last were addressed dur- dam (79 (315 and control ha) (Fig. 2 ing this study. arm (227 and Table 1). A fifth area, the slag pond, con- This investigation evaluates some of tains 32 ha of water. The land surround- the benefits and disadvantages of large ing Lake Sangchris is intensively farmed numbers ( > 100,000) of waterfowl that for com and soybeans. congregate each autumn at Lake The Kincaid Generating Station, Sangchris and in close proximity to the which began generating electricity for Kincaid Generating Station — a large commercial consumption in 1967, is (1,232 MW) coal-fired generating facility between the discharge and intake arms that is owned and operated by Com- of Lake Sangchris (Fig. 2). Water is taken monwealth Edison Company. Approx- from the intake arm, circulated through imately half of the waterfowl present at the plant, and returned to the discharge Lake Sangchris during October, (warmwater) arm of the lake. The Kin- November, and December are attracted caid plant consumed 2.7 million metric to the slag pond, a diked area adjacent to tons of coal in 1972 (National Coal the power plant. Association 1974:9). When burned in this plant, coal is reduced to 15 percent of its STUDY AREA original weight. About half of the residue Lake Sangchris is a man-made body is slag, which is slurried into the slag of water In northwest Christian County, pond immediately northeast of the plant central Illinois (Fig. 1). The lake, formed (Fig. 2). The slag pond serves as a settling — 658 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 DAM AREA Fig, 2. The Lake Sangchris-Kincaid Generating Station complex as segmented into areas for studying waterfowl. The five areas are the dam area and slag pond— no hunting, fishing, or trespassing; discharge arm— fishing permitted but no hunting; control arm and intake arm— hunting permitted but no fishing. The restrictions for the slag pond are permanent. Restrictions for the other areas were in effect during the waterfowl hunting seasons only, beginning in 1974. Stations where water temperatures were taken are indicated by circles. Table 1. —Surface area of water and length basin; excess water is returned to the lake of shoreline for the intake arm and for the via a large (122-cm diameter) pipe that ^ discharge arm of Lake Sangchris. empties into the discharge canal. Thus, Arm of Surface Area Shoreline water level the slag is held Lake (ha) (km) the in pond relatively constant. The plant's twin Discharge arm 250(44.2)2 49(48.5) Intake arm 315(55.8) 52(51.5) smoke stacks are equipped with elec- 'Percentage of (he total of these two areaa. trostatic precipitators that remove 99 per- . Aug. 1981 Sanderson & Anderson: Waterfowl 659 cent of the fly ash from the atmospheric age, and body weight of each of those discharge. birds were determined, after which the gizzard (1974) or gizzard and proven- METHODS triculus (1 975) were removed and stored in a Water temperatures were taken at the freezer. The contents of each gizzard and surface at eight locations (stations 1, 2, 3, each proventriculus were screened (no. 35 A, 4, B, 5, and 7) in Lake Sangchris (Fig. mesh) and washed to divide them into 2). These data were collected at approx- two fractions: (1) plant and animal imately biweekly intervals from October material (except for shells) and (2) grit, 1974 to March 1977 under the supervi- shells, slag, and lead pellets. The fre- sion of John A. Tranquilli or Allison R. quencies of occurrence and amounts of Brigham, Associate Aquatic Biologists, com, soybeans, and other important Illinois Natural History Survey. foods were determined for mallards and Counts of the numbers and species of wigeons; analyses of these materials col- lected in 1974 were limited to birds that waterfowl at Lake Sangchris and on the "appreciable amounts" Ig for slag pond were made primarily by Robert had (^ >. for wigeons, dry D. Crompton, Field Assistant, Illinois mallards and 0.25 g in the gizzard. The fre- Natural History Survey, while riding in a weight) of food quencies of occurrence of Corbicula small aircraft flying at about 122 m (400 shells, slag, and lead pellets were deter- feet) above mean ground level. The cen- tor all species representee suses were begun on 15 November 1972 as mined part of another study. At first, only the Mallards used for the slag-feeding species of waterfowl for total number and study were juvenile males hatched and the entire area were recorded. Counts reared at the Max McGraw Wildlife were 1 day each week, weather per- made Foundation, Dundee, Illinois. Those mitting, during fall and winter from 16 ducks were transported on 15 September 1974 to 13 April 1977. The October 1976 to LIrbana, where they were held in numbers of birds present were recorded a 3.0- X 6.1-m pen 1.8 m high and equip- the portion of the lake they according to ped with a wire floor; they were fed com- occupied — discharge arm, for example. mercial chow and whole kernel com. On These censuses were supplemented by 30 September, 40 ducks were placed in observers located on the counts made by eight 1.5- X 1.5-m pens (5 ducks per pen), particularly during September ground, also 1.8 m high, equipped with wire and October. floors. They were fed a mixture of com- The methods used to investigate the mercial maintenance chow and ground impact of the power lines on waterfowl com and given water via automatic were previously described by Anderson watering devices. (1978). Briefly, the slag pond was search- Ten ducks (two pens) were placed on ed I day each week for dead and crippled each of four experimental diets on 1 1 Oc- birds, which were saved and autopsied, tober. The diets, given ad libitum, were and observations were made to determine (1) ground com, (2) ground corn to the flight patterns of birds relative to the which slag had been added, (3) commer- slag pond and the power lines. The cial maintenane chow, and (4) commer- resulting data were integrated with the cial maintenance chow to which slag had results of the weekly waterfowl censuses been added. The slag was added to the for purposes oi analysis. com and chow at the rate of 2.5 percent Because waterfowl hunting was per- of these diets (dry-weight basis), mitted at Lake Sangchris on a controlled thoroughly mixed, and pelleted (4.5-mm basis (hunters had to report to a check diameter). The control diets were also I station both before and after hunting), pelleted. Unfortunately, it was discovered i beginning with the fall of 1974, it was at the conclusion of the experiment that possible to examine several hundred water- the diet consisting of ground corn was ' fowl shot by hunters. The species, sex, contaminated with slag at the rate of 0.42 660 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 Waterfowl in the refuge located near the dam at Lake Sangchris. percent of the diet and, therefore, was W = number of waterfowl (all species not a true control. combined) present F = grams of fecal material excreted The body weight and packed cell per bird per day volume (PCV) were determined for each P = proportion of the fecal material duck at the beginning of the study (11 that is nitrogen or phosphorus. October) and after 1, 2, 4, 6, and 8 weeks The 0.8 multiplier was used to correa for of being on the experimental diets. All the fact that not all fecal material was ex- ducks were killed (decapitated) at the end creted into the water. The 80-percent of the 8th week (6 December) and autop- value was selected after considering the sied. The liver, both kidneys, the gizzard mallards at with proventriculus attached, and both behavior and daily routine of Sangchris. adrenal glands were excised, freed of ex- Lake traneous material, and weighed. In these calculations, F= 16.7, and P= 0.0624 for nitrogen and 0.0348 for Calculations of nutrient loading— the phosphorus. These values are based on in- amounts of total nitrogen (N2) and formation obtained from mallards fed ex- available phosphorus (P2O5) that water- clusively on shelled corn. That is, captive fowl add to Lake Sangchris — were made, mallard hens fed only corn during winter using the formula: consumed an average of 57 g per day and excreted an average of 8.0 g (dry weight) of \F\ Px 0.8 contained an N = W feces per day, and the feces 1,000 average of 6.24 percent nitrogen and 3.48 where: percent phosphorus (Ronald F. Labisky, N = kg of nitrogen or phosphorus per Illinois Natural History Survey, Urbana, day unpublished data). Bossenmaier & Mar- ^ Aug. 1981 Sanderson & Anderson: Waterfowl 661 shall (1958:24) estimated that wild 1973, 1974, and 1975. The other studies mallards could consume as much as 197 g were begun in the fall of 1974 and con- of wheat per day — a value that is reduced tinued through the spring of 1977. to 181 g when applied to corn. For lack of a better value, we selected 1 19 g (halfway ACKNOWLEDGEMENTS between 57 and 181) as the average W. Seets, Sarah S. Hurley, amount of corn eaten per mallard per James John A. Tranquilli, Richard W. Kocher, day. The corresponding value for feces is and Herbert M. Dreier, Illinois Natural 16.7 g (F/8.0 = 119/57). All of the weight History Survey, assisted with many phases 1 data are given on a dry-weight basis. of the fieldwork. John Kube, Mike Mur- weight of feces excreted per The dry phy, and Nels Hanson, Illinois Depart- relation to weight was deter- day in body ment of Conservation, helped collect giz- of captive geese mined in several species zards and assisted with other aspects of in wild geese by Kear (1963) and Canada the fieldwork. Frank C. Bellrose provid- by Manny et al. (1975). The average ratio ed advice during the study and reviewed weight of dry feces per day to body was the manuscript. Stephen P. Havera average weight of 2.25 percent. The assisted with the statistics and also review- mallards of all ages and sexes bagged at ed the manuscript. Helen C. Schultz Lake Sangchris was 1,135 g (Table 12). edited the original manuscript. Thus, if we used these figures (1,135 g X The Max McGraw Wildlife Founda- 2.25 percent = 25.5 g), we would have tion, Dundee, Illinois, Dr. George V. 25.5 g of dry feces produced per duck per Burger, General Manager, provided day instead of 16.7 g. Kear (1963) research grants that partially financed reported 2.2 percent nitrogen and 1.0 these studies. percent phosphorus and Manny et al. (1975) reported 4.38 percent nitrogen and 1.34 percent phosphorus in the dry FINDINGS feces of the geese they studied. Paloumpis WATER TEMPERATURES & Starrett (1960) used data from Sander- The distribution of water son (1953), who reported that 1,000 temperatures at the surface of Lake domestic ducks produced an average of Sangchris from October to March was 5.7 lb of nitrogen and 7.6 lb of much the same for each of the three phosphorus per day. Paloumpis & Star- seasons of our study (Table 2). Except in rett arbitarily used 0.50 as a correction October 1976 when they were almost the factor for the lower food intake and same, mean monthly temperatures were smaller size of wild ducks. If we used always greater in the discharge arm (sta- these figures, we would calculate that tions A, 4, B, and 5), which receives each wild mallard produced 1.29 g of heated water from the power plant, than nitrogen and 1.72 g of phosphorus per in the intake arm (stations 1 and 2). day. Thus, if the mallards at Sangchris Temperatures in the dam area were excrete 25.5 g of dry feces each day, that generally intermediate between those in the amount would contain 5.0 percent discharge arm and the intake arm. percent nitrogen (1.29/25.5) and 6.7 When tested by Wilcoxon's sign rank- total phosphorus (1.72/25.5). If we ed test (Steel & Torrie 1960:402), all dif- averaged the three sets of published ferences in mean surface-water figures for nitrogen and phosphorus, we temperatures from one portion of the would have 3.86 percent for the amount lake to another were significant (P< 0.05) of nitrogen and 3.01 percent for the for 1974-1975. All differences in the dry feces in- amount of phosphorus in surface-water temperatures, except those percent nitrogen and 3.48 stead of 6.24 from the intake arm and the control arm, percent phosphorus. were also significant in 1975-1976. In The studies of waterfowl-power line 1976-1977 all differences in surface- interactions were conducted intensively in water temperatures were significantly dif- 662 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 < r. o o c o O a E 0) I n Aug. 1981 Sanderson & Anders<)n: Waterfowl 663 ferent, except those from the discharge half of March, then decreased to only ' arm and the dam area and the intake 2,432 birds on the 19th and 1,355 on the arm in October, the dam area versus the 26th of March. control area in February, and the intake During the 1975-1976 season, the arm versus the control arm in February. October and November populations were Temperatures of water in the slag pond substantially lower than the populations were recorded only five times during this in the same months in the previous year study. They were similar to the (Table 3), but the mean populations for temperatures in the intake arm and con- December and January were similar for trol arm during October, November, and the 2 years. The peak population December 1975 (Table 2). However, (101,185) for the season was reached on temperatures recorded in the slag pond 19 November 1975 and was somewhat during February and March 1976 tended lower than the peak population (111,496) to be relatively warm— approaching for the 1974-1975 season reached 26 those in the discharge arm. Because the November 1974. amount of water in the slag pond is com- The peak population of the paratively small, its temperature might 1976-1977 season was only 72,868 birds be expected to decrease and increase at counted on 27 November 1976. On the faster rates than the temperatures of the other hand, the mean number of birds various arms of Lake Sangchris. present in October (11,432) was the highest recorded for this month. The dry WATERFOWL POPULATIONS fall of 1976-1977 resulted in much fall Numbers plowing of com stubble. Thus, little food The highest count of waterfowl was available for mallards and geese, recorded for Lake Sangchris during the which feed on waste corn. The mean present study was 177,035 birds on 29 numbers of waterfowl present in Novem- ber, December, and November 1972. Of those, 168,000 were January were lower average, mallards and 8,000 were black ducks. For than whereas the numbers pres- ent in February 1977 (13,916) were the 1973-1974 season, censuses were not initiated until 6 December. There were slightly higher than average (11,736, more than twice as many waterfowl at Table 4). Lake Sangchris during December, Species Composition January, and February 1974-1975 as during the same months in 1973-1974 Mallards were the most abundant (Table 3). waterfowl species — constituting from Mean numbers of waterfowl at Lake nearly 50 percent (October) to 95 percent Sangchris and on the slag pond increased (December) of the total population — during from 6,667 during October to 76,154 in fall and winter from October 1974 November and to 81,480 during through March 1977 (Table 5). From December 1974 (Table 3). The max- November through January, mallards imum number counted in 1974 was ap- constituted more than 90 percent of the proximately 111,500 on 26 November total population. Black ducks made up a and again on 4 December. Waterfowl small but consistent portion (2.5-3.0 numbers decreased substantially during percent) of the population from October the latter half of December 1974 and the through March. Coots and wigeons made first part of January 1975. Mean numbers up sizable portions (23.4 and 12.6 per- were 29,228 during January and 13,271 cent, respectively) during October, as did during February 1975. The population Canada geese in October, January, held steady during February and the first February, and March (2.5, 3.9, 12.1, and 664 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 Table 3. —Numbers of waterfowl (ducks, geese, and coots) counted on Lake Sangcfiris and the slag pond from November 1972 to Marcti 1977. The counts were made from small aircraft.^ Dam Remainder Slag Date Area of Lake Pond Total 1972 Aug. 1981 Sanderson & Anderson: Waterfowl 665 Table 3. —Continued. Dam Remainder Slag Date Area of Lake Pond Total 5 666 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 4, —Average numbers by month of each species of waterfowl at Lake Sangchris and the slag pond from October 1974 through March 1977. Species Oct. Nov. Dec. Jan. Feb. Mar. Surface-feeding ducks Mallard 3,766 Black duck Pintail Wigeon Blue-winged teal Green-winged teal Gadwall Shoveler Diving ducks Scaup Ring-necked duck Canvasback Redhead Ruddy duck Goldeneye Mergansers Geese Canada goose Blue & snow goose Coot Average number of waterfowl present 7.666 63,384 72,007 27,149 11.736 6.028 Table 5. — Percentage composition of waterfowl present at Lake Sangchris and the slag pond from October 1974 through March 1977. ' ! • Aug. 1981 Sanderson & Anderson: Waterfowl 667 oo in — a^ oi — o o o V •— -^ iTi tD 04 id o^ o N C^i CT) O O O in o 00 r^ t^ Tf O (M O ^ o ^ in ^ oo o N O O O do d d -^ V -.J- o ^ o o o ^ o O — CN o o (N d d odd d d d in — d d o o o ^ o o — (>j d d odd d d d d V ir> CM in o o o ^ o in on w d --' (zi d iz> d d V d d ^ o o o o o ^ o o o CNi d d d d d d d d d V in — to o o o o o c^ d d c> d <6 d d V r^ o Tj" o o o (N d (N odd o V r^ o ^ o o o o ^ o o ^ ^ cvi d d <6 c> d d d i:^ V V 00 r- lO ^ o o ,— —. o o ^ ^ c^i d d d c> d> d d> c> V V V V V r-» --« in — on 00 i ^ o ^ ^ o oj d ^ odd o o V V in ^ on on on ^ G^i d ifi d> c6 d V V to 0^ oi on (N ^ 94 d d d d d V V in oi o ^ on '-' -^ iri ^ d 14.6 percent). Other species constituting unusually severe weather (lower thctn more than 2.0 percent of the population average temperatures) that prevailed. for a month included pintail (4.6 per- These low temperatures were reflected in cent, October), wigeon (2.6 and 4.3 per- lower mean water temperatures in cent in November and March), lesser December 1976 and January 1977 (Table scaup (2.4 percent, March), ring-necked 2). duck (3.5 percent, March), canvasback Mallards— Lake Sangchris Versus percent, March), and coot (2.5 and (2.7 The Illinois Valley percent, November and March). 4.4 The increase and subsequent decrease in Species that showed substantial varia- numbers of mallards at Lake Sangchris tion from month to month in the percen- during the falls and winters of tage that they contributed to the total 1972-1973 through 1976-1977 ex- population at Lake Sangchris (Table 5) hibited a pattern similar to that for the Il- were the mallard (49.1 percent in Oc- linois River valley (Fig. 3). As might be tober to 95.4 percent in December), expected from the location of the Illinois wigeon (0.9 percent in December and River valley, approximately 100 km to February to 12.6 percent in October), the northwest, the fall buildup at Canada goose (0.3 percent in November Sangchris occurred 1 — 2 weeks later than to 14.6 percent in March), and coot ( < 0.1 along the Illinois River. However, after percent in December and January to 23.4 the peak population was reached in percent in October). The average November, mallards departed from Lake numbers of these and other species pres- Sangchris at about the same rate as from ent each month are shown in Table 3. the Illinois River valley, at least through early January. Counts were not available Canada geese showed the greatest month- for the Illinois Valley after the first week ly percentage variation from year to in January until after the first of March. year (Table 6). They comprised 0.8 per- pattern of use by rhallards was cent of the waterfowl present in February The similar for Sangchris and the Illinois 1977 and 24.0 percent in February 1976. Valley, as by the percentage of the Mallards comprised 46.0 percent of the shown spring count present on several Sangchris population in March 1976 and peak dates in the two areas (Fig. 3). However, 68.9 percent in March 1977, and coots there were relatively far fewer mallards constituted 12.0 percent of the popula- on Sangchris in March than from Oc- tion in October 1974 and 30.4 percent in tober through early (Tables 4 October 1975. January and 7). Whereas peak fall and winter The differences in percentage composi- populations on Sangchris averaged about tion of each species from month to month 12 percent of the peak numbers in the Il- (Table 5) are related to average food, linois Valley, in March the figure was water, and weather conditions and to the slightly less than 1.5 percent. habits of each species. For example, coots migrate early and constitute a substantial percentage (23.4) of the population in EFFECTS OF TEMPERATURE October but a low percentage (2.5) in ON DISTRIBUTION November even though approximately OF WATERFOWL equal numbers of coots are present in Oc- One of the primary objectives of this tober and November (Table 4). The dif- study was to determine if waterfowl were ferences from year to year are a result of attracted or repelled by the heated water annual variations in food, water, and in the discharge arm of Lake Sangchris weather conditions. For example, the (Fig. 2). The dam area is an inviolate overall low populations at Sangchris in refuge during the waterfowl hunting December 1976 and January 1977 (Table season, encouraging a greater concentra- hunting 6) probably resulted from the lack of tion of waterfowl there. Duck available corn because of higher than was permitted in the intake arm and con- average amounts of fall plowing and the trol arm but not in the discharge arm. Aug. 1981 Sanderson & Anderson: Waterfowl 669 100- go- so- 70- Fig. 3, — Relative abun- 60- dance of mallards at Lake 50- Sangchris and in the Illinois 40- River valley from Spring Valley to Meredosia during fall and 30- winter from 1972-1973 20- through! 1976-1977. = ILLINOIS VALLEY 10- = LAKE SANGCHRIS 0- ' ' ' M M M ' ' 1I15I29I12I25I12I26I9I I I I 18 2 16 30 13 11 11 25 8 22 5 19 5 19 2 SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. Fishing was not permitted in the intake "avoidance of the cooler water," we arm or the control arm during the water- recognize that any correlations between fowl hunting season. However, fishermen duck density and water temperature may were allowed in all areas except the slag be results of factors other than a response pond before and after the waterfowl to water temperature per se. Thus, food season. Thus, hunting was a factor in- might be more abundant and available in fluencing waterfowl use in the unit with the heated (or unheated) water than in unheated water and fishing was a factor the unheated (or heated) water. The in the unit with heated water. presence of waterfowl attracted to the Although we will use such terms as food might in turn attract other water- "preference for the warmer water" and fowl with different feeding habits to the Table 7. —Average numbers by month of each species of waterfowl in the Illinois Valley from September 1974 through March 1977. Species Sept. Oct. Nov. Dec. .Ian. Mar. Surface-feeding ducks Mallard 11,833 Black duck Pintail Wigeon Blue-winged teal Green-winged teal Gadwall Shoveler Diving ducks Scaup Ring-necked duck Canvasback Redhead Ruddy duck Goldeneye Mergansers Geese Canada goose Blue & snow goose Wood duck Coot Average numbeT of waterfowl present 670 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 8. — Numbers of waterfowl counted on ttie discharge arm (warm water) and Intake arm (cold water) of Lake Sangchris from October tfirough Marcti— 1974-1975. 1975-1976. and 1976-1977. Aug. 1981 Sanderson & Anderson: Waterfowl 671 Table 8, —Continued. 672 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 8. —Continued. Aug. 1981 Sanderson & Anderson : Waterfowl 673 Table 8. —Continued. 674 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 8. —Continued. Monti Aug. 1981 Sanderson & Anderson: Waterfowl 675 same area, and this second group might Counts of waterfowl in these two areas of continue to use the area because of habit. Lake Sangchris from October through Similarly, hunting, fishing, and other March-1974-1975, 1975-1976, and human activities might cause waterfowl 1976-1977 — are summarized by months to develop patterns of use not directly and years in Table 8. The various species related to water temperature. were partitioned into seven groups on the basis of similarity in food habits and As mentioned earlier, surface-water habitat preferences. For example, temperatures from one portion of the mallards and black ducks were placed in lake to another were generally one group and scaups, ring-necked significantly different (Table 2). Although waterfowl numbers were ducks, canvasbacks, and ruddy ducks were placed in another gfroup. counted on five areas of the lake, in our efforts to determine the effects of heated Although paired <-tests indicated no water on the distribution of waterfowl, we significant differences (P>0.05) in the have compared populations only on the population densities of all waterfowl com- discharge arm (heated water) with bined by months for the 3 years of these populations on the intake arm (unheated studies on the discharge arm versus the water). The two areas are roughly similar intake arm, the general pattern for all in size, length of shoreline, directional waterfowl combined was for nearly equal orientation, and proximity to the refuge concentrations (number of waterfowl per at the dam and the slag pond (Table 1 100 ha per census) on the two areas in Oc- and Fig. 2). tober (P> 0.10), a tendency to select = DISCHARGE ARM (wARM WATER) = INTAKE ARM (cOLD WATER) Fig. 4, — Mean number of all waterfowl per 100 ha per census on the discharge arm at Lake Sangchris as compared with the intake arm, October-March 1974-1377. = DISCHARGE ARM (wARM WATER) = INTAKE ARM (cold WATER) Fig. 5. —Mean number of mallards and black ducks per 100 ha per census on the discharge arm at Lake Sangchris as compared with the intake arm, October- March 1974-1977. 676 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 heated water in November and December time at Lake Sangchris, were absent in {P> 0.10), a slight preference for heated January and February, and were virtually water in January (P>0.90), no selection absent in December (Table 8 and Fig. 6). in February (P>0.90), and a preference Coots showed no preference for the for unheated water in March (P> 0.05) heated water in October, preferred it in (Table 8 and Fig. 4). November, were virtually absent from December through February, and showed Because mallards and black ducks con- a slight avoidance of the heated water in stituted a majority of the population in March (Fig. 7). all months (especially mallards, which constituted from 49.1 percent of the total Pintails and wigeons were always present population in October to 95.4 percent in in low numbers at Lake Sangchris and December, Table 5), it is not surprising showed no significant reaction to water that they showed a pattern with respect to temperatures (Fig. 8). Scaups, ring- water temperature that was almost iden- necked ducks, canvasbacks, and ruddy tical to that of all waterfowl combined ducks were never present in large (Fig. 5). The surface-feeding species that numbers at Lake Sangchris, and they too feed strictly in aquatic environments showed little or no preference with (blue-winged teal, green-winged teal, respect to water temperature (Fig. 9), ex- gadwall, and shoveler) avoided the cept perhaps in March, when they show- heated water in October and March. In ed a slight avoidance of the unheated November they showed no preference in water. Goldeneyes and mergansers were relation to water temperature (Fig. 6). present in low numbers from December These species were not abundant at any through March. They seemed to prefer DISCHARGE (WARM WATER) INTAKE ARM (COLD WATER) Fig. 6. — Mean number of blue-winged teals, green- winged teals, gadwalls, and shovelers per 100 ha per census on the discharge arm at Lake Sangchris as compared with the intake arm. October-March 1974-1977. DISCHARGE ARM (WARM WATER) INTAKE ARM (COLD WATER) Fig. 7 — Mean number of coots per 100 ha per census on the discharge arm at Lake Sangchris as compared with the intake arm. October- March 1974-1977. Aug. 1981 Sanderson & Anderson: Waterfowl 677 600 DISCHARGE ARM (WARM WATER) — = INTAKE ARM (cOLD WATER) 550 500 450 Fig. 8. — Mean number of 400 pintails and wigeons per 100 ha per census on the 350 discharge arm at Lake 300- Sangchris as compared with the intake arm, October- 250- March 1974-1977. 200 150- 100- LlJ OQ 50- OCT oo oo 45 DISCHARGE ARM (WARM WATER) 40 INTAKE ARM (cOLD WATER) 35 Fig. 9. — Mean number of scaups, ring-necked ducks, 30 H canvasbacks, and ruddy 25 ducks per 100 ha per census LlJ on the discharge arm at Lake Q- 20 Sangchris as compared with CO 15 the intake arm, October- (_)m March 1974-1977. 10 u_ o 5 NOV. DEC. JAN. FEB. MAR. oo ZD OO UJ <_) en 45-] = DISCHARGE ARM (WARM WATER) 40- = INTAKE ARM (cOLD WATER) Fig. 10. —Mean number of goldeneyes, common 35- mergansers, and hooded 30- mergansers per 100 ha per 25- census on the discharge arm at Lake Sangchris as CO 20- compared with the intake arm, CJ 15- October-March 1974-1977. 10- C3 5- UJ BO OCT the heated water from December through from October through March. No doubt February, but had no preference in many of the geese in the general area March (Fig: 10). were feeding in nearby cornfields when Geese (virtually all Canada geese) were the censuses were made. Those on the present in relatively low concentrations lake seemed to prefer the heated water in 678 Ilunois Natural History Survey Bulletin Vol. 32, Art. 4 CO 13U-1 Aug. 1981 Sanderson & Anderson: Waterfowl 679 Table 10. —Mean body weight and standard errors, in grams, of mallards, wigeons, and lesser scaups bagged by hunters at Lake Sangchris from 24 October to 10 December 1974, from 24 October to 8 December 1975, and from 23 October to 9 December 1976, Sample sizes are in parentheses. Year 680 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 mean weights of mallards bagged late in 286 mallards were 43, 67, and 4.9 per- the hunting season were greater than cent. In 1975, 702 gizzards from 16 those of mallards bagged early in the species were examined: 29 percent con- season (Table 11). tained Corbicula, 51 percent contained slag, and 1.6 percent contained lead Juvenile female mallards at Sangchris pellets (Table 13). Values for 407 weighed 978 g as compared with 1,048 g mallards were 36, 54, and 1.2 percent. for a large series reported by Bellrose Both Corbicula and slag were found in (1976:229). Juvenile male mallards at most of the species represented in the Sangchris averaged 1,166 g compared sample — the exceptions had small sample with 1,193 g reported by Bellrose sizes. (1976:229). Adult female (1,110 g) and As in 1974, the incidence of Corbicula adult male (1,285 g) mallards at Sangchris weighed more than the average and slag in gizzards of mallards, wigeons, weights reported by Bellrose (1976:229) and lesser scaups examined in 1975 in- creased as the hunting season progressed for adult females (1,107 g) and adult (Table 14). The incidence of lead pellets males (1,247 g). Among wigeons and lesser scaups bagged by hunters at decreased for mallards and wigeons but Sangchris, only adult female lesser scaups not for scaups. had average weights that were heavier Field observations at the Lake Sangchris- than the mean weights reported by Kincaid Generating Station complex in Bellrose (1976:198, 343) for these two 1973, 1974, and 1975 revealed that species. waterfowl make extensive use of the power plant's slag pond during the fall HABITS FOOD months. As many as 90,000 birds were Examination of the contents of counted at one time on this 32 -ha body of stomachs from ducks bagged by himters water, and 40,000 were commonplace. revealed that mallards at Lake Sangchris Waterfowl are attracted to the slag pond relied heavily on com for food (Table 12). because it provides an abundance of food Foods in gizzards, taken from ducks in in the form of brittle naiad (Najas minor) 1974, suggested that 88 percent of the and other aquatic plants and because it mallards' diet was corn. Moreover, foods serves as a refuge — the slag pond is not in proventriculi, taken from ducks in open to the public. However, there are 1975 and considered more reliable than several reasons for being concerned about gizzards for determining food habits, in- the welfare of waterfowl that congregate dicated that virtually 100 percent of the on slag ponds, one of which is the possible mallards' diet was corn. adverse effects of ingested slag on the birds. This concern came sharply into In 1974, 453 gizzards from 16 species of focus with the discovery that 57 percent waterfowl were examined for the of the 1,155 gizzards examined in 1974 presence of Corbicula shells, slag, and and 1975 contained slag. lead pellets. The percentages of gizzards in which these items occurred was 36, 66, Findings of other researchers at Lake and 3.8 percent, respectively. Values for Sangchris suggest that, in general, the Table 1 2. —The relative importance of corn in the diet of mallards at Lake Sangchris from October to December in 1974 and 1975. The data were obtained by examining the contents of gizzards (providing gizzard contained >1 g of food) in 1974 and the contents of proventriculi in 1975. Gizzards or Percent of Gizzards Percent Corn Constituted Proventriculi or Proventriculi in of all Foods in all Year Examined Which Corn Occurred Gizzards or Proventriculi^ 1974 66 89.4 87.7 1975 68 97.1 99.9 'Only gizzards were collected in 1974. In 1975 kinds of food ingested were dctennined from proventriculi. and amounts oi Corbicyda shells. slag, and lead shot were determined from gizzards. Aug. 1981 Sanderson & Anderson: Waterfowl 681 Table 1 3. —The incidence of Corbicula shells, slag, and lead shot in gizzards of waterfowl bagged by hunters at Lake Sangchris between 24 October and 11 December 1974 and 24 October and 8 December 1975, 682 IixiNOis Natural History Survey Bulletin Vol. 32. Art. 4 The slag pond adjacent to the Kincaid Generating Station, where waterfowl congregate in the fait. important waterfowl foods. Corbicula if any, of prescribed amounts of ingested was favored somewhat by the heated slag on captive mallards for an extended water (Dreier & TranquilH 1981), period of time. The experimental birds whereas other macroinvertebrates— pri- were fed slag from 1 1 October to 6 marily Chaoborids and Chironomids— December 1976. in abundance be- exhibited no change All 20 ducks fed corn or commercial , tween the intake and discharge arms maintenance chow and all 20 ducks fed Several species of fishes (Webb 1981). com and slag or chow and slag survived concentrate in the heated water during the entire 8-week feeding period. Fur- the winter al. months (TranquilH et 1981) thermore, no ducks were emaciated or but are not ordinarily consumed by obviously sick at the termination of the waterfowl, except for mergansers and experiment. The mean weight of ducks goldeneyes. fed chow and slag was appreciably less than the mean weight of the ducks fed RESPONSES OF MALLARDS TO chow, both at the beginning of the ex- INGESTED SLAG periment and at the end (Table 15). At The purpose of this phase of the in- the latter time the difference was vestigations was to determine the effects, statistically significant. Mean weights of Table 15. — Body weights of juvenile male mallards fed exclusive diets of corn, corn plus slag, commercial maintenance chow, or chow plus slag for an 8-week period — 1 1 October-6 December 1976. Aug. 1981 Sanderson & Anderson: Waterfowl 683 the ducks fed corn and of those fed corn However, the differences were not signifi- and slag were similar at the beginning of cant. the study and also at its termination. The The patterns of change in body weight ducks fed corn and those fed chow gained during the experiment for the ducks fed more weight, on the average, than their corn and slag and those fed com were counterparts receiving slag (Table 15). almost identical through the 4th week Fig. 12. —Mean change in body weight of juveniie +100 male mallards fed corn or corn plus slag for 8 weeks. Vertical lines indicate standard errors. The mean initial and final body weights T^T (12299) for each group of ducks are given in parentheses. None of the differences between means for the weekly and biweekly periods were statistically significant (P>0.05). N = 10 in each group. (DEC. 6) WEEKS OF STUDY 1 684 Illinois Natural History Survey Bulletin Vol. 32, An. 4 (Fig. 12). Similarly, the patterns of the 4th and 6th weeks the ducks fed com change for the ducks fed chow and slag and those fed chow lost an average of 43 and and those fed chow were also much alike 50 g, respectively. For purposes of com- through the 4th week (Fig. 13). Between parison, the ducks fed com and slag gain- Fig. 15. —Mean change in packed cell volume (PCV) for juvenile male mallards fed 3 chow or chow plus slag for 8 weeks. Vertical lines indicate standard errors. The mean in- itial and final PCVs for each group of ducks are given in parentheses. Statistically significant (P<0.05) dif- ferences occurred between means for the two groups of ducks at the ends of the 4th and 6th weeks. N = 1 in each group. WEEKS OF STUDY Table 16. —Mean weights (plus or minus the standard error) of the liver, kidneys, gizzard and proventriculus, and adrenals from juvenile male mallards fed corn or corn plus slag for 8 weeks— 1 October-6 December 1976. The differences between paired means are not statistically significant. N = 10 in each group. Percent of Body Weight Weight at End of Experiment Organ or Gland Com Com + Slag Com Com + Slag Liver 20.6 ± 1.0 g 19.1±0.8g 1.68 ±0.08 1.55±0.05 Kidneys 5.9±0.2g 5.9±0.2 g 0.49 ±0.02 0.49±0.02 Gizzard and proventriculus S1.4±0.9g 3S.2±1.0g 2.57 ±0.08 2.71±0.06 77.8±5.0a 3.4a Adrenals 95.8 ±6.8 mg |92.8±S.7 mg 76.2 ± •PtrcCTt X 10'' Table 17. —Mean weights (plus or minus the standard error) of the liver, kidneys, gizzard and proventriculus, and adrenals from juvenile male mallards fed commercial maintenance chow or chow plus slag for 8 weeks— 1 1 October-6 December 1 976. N = 1 in each group. Percent of Body Weight Weight at End of Experiment Organ or Gland Chow Chow + Slag Chow Chow + Slag Liver 25,l±1.2g 24.0±1.5g 1.87±0.06 1.97±0.12 Kidneys 8.6±0.3^ 8.3±0.5g 0.64±0.02 0.68 ±0.03 Gizzard and proventriculus 41.8±1.0g» S7.4±l.l g^ 3.12±0.09 S,07±0.10 90.6±5.1 94.3 ±2.8 73.6±4.0'' 77.4±3.0b . Adrenals mg mg *Thc difference between means is sutistically significant (P in of Table 1 8.—Mean weights in grams (plus or minus the standard error) of grit and slag gizzards juvenile male mallards fed corn, corn plus slag, commercial maintenance chow, or chow plus slag for 8 weeks— 1 1 October-6 December 1976. N = 10 in each group. Item Com Com + Slag Chow Chow + Slag 0.74±0.14b Grit 1.08 ±0.20 0.87±0.11 1.62±0.19'' Slag 0.77 ±0.09* 2.21 ±0.21* O.OOb 2.40 ±0.29'' Total 1.8S±0.24'' 3.08 ± 0.19' 1.62±0.19^ }. 14 ±0.29^ •The difference between paired meant is uatistically ugnificant (P The amounts of total nitrogen and of arm of Lake Sangchris is compounded by available phosphorus deposited in Lake many variables. However, two factors Sangchris by waterfowl in 1974—1975, loom above all others: food and protec- Table 19. —Amounts of total nitrogen {N2) and of available phosphorus (P2O5) in kilograms per hectare of lake surface added to Lake Sangchris and the slag pond by waterfowl from October to March, 1974-1975, 1975-1976, and 1976-1977. 686 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 tion — or their counterparts, lack of food avoid the heated water during March. and disturbance. For species that feed in Positive responses to the discharge arm cornfields and soybean fields (mallard, were most pronounced among fish-eating black duck, pintail, wigeon, and geese), species — goldeneye and mergansers — and sources of food are relatively plentiful at occurred during months when water Lake Sangchris. All other species that temperatures and air temperatures were stop over at Lake Sangchris (teals, gad- relatively low. These ducks were almost wall, shoveler, diving ducks, mergansers, certainly attracted to gizzard and coot) are restricted to aquatic en- shad — which comprised 76.3 percent of vironments for feeding activities. Thus, the lake's standing fish crop (Tranquilli the heated water could affect the latter et al. 1981) — that concentrate in the group of birds indirectly by influencing, heated water during the wfinter months. either favorably or unfavorably, plants We obtained no evidence during and animals that they use for food. three fall-winter-spring periods that the Obvious sources of disturbance are (1) heated water in Lake Sangchris altered hunting activities — permitted in the in- the chronology of migration of mallards take arm and control arm during the through central Illinois (Fig. 3). In fact, waterfowl hunting season, (2) fishing ac- the data suggest that mallards departed tivities—permitted in the discharge arm from Sangchris during November and during the hunting season and in the en- December for more southern latitudes on tire lake at all other times, and (3) the same dates and in the same aquatic biologists' research — conducted on magnitude as from the Illinois River the entire lake but often involving the full valley. Similarly, the mallards' migration length of the discharge arm because the northward in spring was neither ac- boat dock was in the discharge canal. celerated nor delayed at Sangchris. The Also, unlike fishes and other aquatic species that spent the entire winter at organisms, waterfowl are directly af- Sangchris (mallard, black duck, wigeon, fected by both air temperature and water goldeneye, mergansers, and Canada temperature. goose) were essentially the same as those The available evidence suggests that that winter along the Illinois River (Tables waterfowl, at least certain species, avoid- 4 and 7). found that surface- ed the discharge arm of Lake Sangchris Brisbin (1974) ducks, diving ducks, and coots in October and March and were attracted feeding generally responded negatively to heated to it during November, December, and portions of a reactor cooling reservoir in January (Table 8). However, were those However, he noted (1974: birds repelled from (attracted to) the South Carolina. severe ice and snow storm in discharge arm or were they attracted to 592) that after a waterfowl abundance and (repelled from) some other portion of the December, richness decreased appreciably on lake? The net result would be the species the unheated water but remained the same — relatively few (relatively many) same in the heated area — findings that birds in the discharge arm. There is little parallel ours for Lake Sangchris during doubt that waterfowl were attracted to at the venter months. Brisbin (1974:585) least one portion of the lake, the refuge in reported that the lesser scaup was the dam area. also water The tendency to avoid the discharge arm much more tolerant of the heated was most evident among species of than its taxonomic cousin, the ring- surface-feeding ducks that rely heavily on necked duck, because the scaup's diet is aquatic vegetation and invertebrates for primarily animal matter and the These food — blue-winged teal, green-winged ringneck is basically a vegetarian. teal, gadwall, and shovelers— and occur- findings also parallel ours. red during months when water tempera- The number of waterfowl lost at Lake tures and air temperatures were relatively Sangchris through collisions with the high (Table 2). Mallards and black power lines that cross the slag pond and ducks, geese, and coots also tended to the lake is not serious in terms of the total Aug. 1981 Sanderson & Anderson: Waterfowl 687 population. At least 114 birds were killed organic (mineral) nutrients. Therefore, or crippled at the slag pond during the the possibility exists that slag, which is fall of each season (Table 9). If we rich in calcium, phosphorus, iron, and assume that we found 58 percent of the birds essential trace elements, would be that collided with the lines at the slag beneficial to mallards maintained on that pond (Anderson 1978:81), the total an- grain. Unfortunately, the diet of corn fed nual kill would be approximately 200 to mallards during the slag-feeding ex- waterfowl. Furthermore, if 200 addi- periment was contaminated with slag. tional birds collided with the lines that Thus, it is not surprising that the ducks cross the lake, the total annual mortality fed com and those fed corn and slag ex- at Lake Sangchris would be about 400 hibited almost identical responses in waterfowl. We consider these estimates terms of changes in body weight, changes conservative. in PCV, and weights of internal organs If for some rejison the number of water- (Tables 15 and 16, Fig. 12 and 14). fowl lost to the power lines increases All 10 ducks fed maintenance chow and substantially, or if additional lines are slag survived the 8-week feeding period, constructed at Lake Sangchris, precau- and 8 of the 10 actually gained weight. tions should be taken to minimize this However, findings of this study suggest cause of mortality. Elxisting lines in prob- that these ducks did not fare as well as lem areas such as the slag pond should those fed chow alone. The former did not be made more visible— painted interna- gain as much weight and had lower PCV tional orange, for example. New lines values during the experiment than the should not be constructed over main por- latter (Table 15 and Fig. 15). Further- tions of the lake or in potential problem more, at the termination of the feeding areas such as sites of future slag ponds. period, the ducks fed chow and slag Waterfowl should not be driven from the weighed significantly less and had slag pond or otherwise discouraged from significantly smaller gizzards- using that body of water. The 32 ha of proventriculi than ducks fed chow water in the slag pond offer the birds (Tables 15 and 17). almost complete protection and provide a It is tentatively concluded that slag is not good source of food in the form of brittle a toxicant of catastrophic proportions naiad and other aquatic plants. The slag when ingested by mallards at levels equal pond, as it now exists, is a major fac- to or below those administered during tor—if not the major factor — con- this study. However, the evidence also in- tributing to the buildup and dicates that ducks would be in better con- maintenance of the waterfowl population dition if they were not exposed to slag for at Lake Sangchris in recent years. long periods of time. Mean body weights (Table 10) and Nutrient loading at the rates of 4 g of stomach contents of mallards suggest that nitrogen and 0.3 g of phosphorus per the physical condition of this important square meter per year have produced game species is good at Lake Sangchris. nuisance conditions in a lake with an Unlike mallards in the Illinois River average depth of 20 m (U.S. Environmen- valley, mallards at Lake Sangchris tal Protection Agency 1973:22). These (Table 11) did not lose weight as the hunt- values equate to 40 kg and 3 kg of ing season progressed. Mallards at Lake nitrogen arid phosphorus, respectively, Sangchris can obtain a nearly perfect per surface hectare of water. If similar diet simply by eating com and Corbicula rates of nutrient loading were to result in (Tables 12 and 13). Com is 78 percent dense growths of aquatic vegetation in carbohydrate (a rich source of calories) Lake Sangchris, where the average depth and the Corbicula provides both flesh (a is only 4.6 m, the amount of phosphorus source of protein) and shell (a source of added to the dam area and the slag pond minerals). by waterfowl was undesirably high, Com, when fed as an exclusive diet, is averaging 14.47 and 20.89 kg, respective- grossly deficient in several organic and in- ly, per hectare (Table 19) for the 3 years. 688 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 The only area where the average amounts whereas scaups, ring- necked ducks, and of nitrogen for the 3 years approached the canvasbacks are the only species most threshold of undesirable levels was in the abundant in March. slag pond, where 37.39 kg per hectare 6. — Mallards comprise from 50 per- (Table 19). The level of were deposited cent of the total population in October to of nitrogen was exceed- 40 kg per hectare more than 95 percent in December. ed for the slag pond in 1974-1975 numbers of mallards arrive (64.59, Table 19). 7. — Peak at Lake Sangchris 1-2 weeks later than previously pointed out, the slag pond As they arrive in the Illinois River valley but supports a dense stand of brittle naiad depart at similar rates from the two during late summer and fall. A cycle of areas. sorts exists in the slag pond among the 8. — In the spring relatively fewer naiad, the waterfowl, and nitrogen and mallards stop at Lake Sangchris than stop phosphorus: the naiad attracts the water- in the Illinois Valley. fowl, which add nitrogen and phosphorus to the water, which promote another 9.— Correlations between waterfowl dense growth of naiad the next year. The population densities and water amounts of nitrogen and phosphorus ad- temperatures at Lake Sangchris may ded annually during the 3-year period to result from such factors as abundance of the two bays west of the dam (48.51 and food, attraction to other species already 29.22 kg per hectare, respectively) are present that have different feeding sufficient to cause eventual development habits, and disturbance by humans of dense stands of vegetation in these rather than from water temperature per shallow areas. se. 10. — Because mallards always com- prised from 50 to 95 percent of the water- CONCLUSIONS fowl at Lake Sangchris, they showed a pattern with respect to water temperature 1 .— Waterfowl populations at Lake that was similar to the pattern showed by Sangchris begin to increase in October all waterfowl combined. with the arrival of substantial numbers of 11.— The pattern for all waterfowl mallards, coots, and wigeons and lesser (and mallards) is for equal concentrations numbers of several other species. on the heated and unheated water in Oc- 2. — Peak numbers for a single count tober, higher concentrations on the are reached in November with the arrival heated water in November and of many more mallards and substantial December, slightly higher concentrations numbers of black ducks. Coot and wigeon on the heated water in January, equal populations remain about the same as in concentrations on heated and unheated October. water in February, and slightly higher 3.— The monthly average for all concentrations on the unheated water in waterfowl present reaches a peak in March. December, when still more mallards arrive, numbers of black ducks remain 12.— Gadwalls, shovelers, and both about the same, numbers of wigeons and species of teals — surface-feeding ducks coots decline, and numbers of Canada that feed in aquatic environments — seem geese increase. to avoid the heated water in October and March, and their concentrations are 4.— The total waterfowl population about equal on the heated and unheated level shows a steady decline from in November. These species are not December through March. water present in January and February, and on- 5. — Although present in relatively low ly a few are present in December. numbers, Canada geese, goldeneyes, and mergansers are the only species that show 13. — Numbers of coots are similar on peak numbers in January and February, the unheated and heated water in Oc- Aug. 1981 Sanderson & Anderson: Waterfowl 689 tober, but their numbers are more con- REFERENCES CITED centrated on the heated water in Anderson, W. L. 1978. Waterfowl collisions with November and on the unhealed water in power lines at a coal-fired power plant. Wildlife March. Few coots are present from Society Bulletin 6 (2): 77-83. December through February. Bellrose, F. C. 1976. Ducks, geese & swans of 14. — Goldeneyes and mergansers, North America. Stackpole Books, Harrisburg, species most abundant in January and PA. 543 p. February, have higher concentrations on , and A. S. Hawkins. 1947. Duck weights in Illinois. Auk 64 (3): 422-430. the heated water from December through February, but their numbers per hectare BossENMAiER, E. L., and W.H. Marshall. 1958. Field-feeding by waterfowl in southwestern are about equal on the heated and Manitoba. Wildlife Monographs 1. 32 p. unhealed water in March. Brisbin. 1. L.,Jr. 1974. Abundance and diversity of 15.— Canada geese show higher waterfowl inhabiting heated and unhealed population levels on the heated water in portions of a reactor cooling reservoir. Pages December and on the unhealed water in 579-593 m J.W. Gibbons and R.R. Sharitz, eds., Thermal ecology. AEC Symposium Series March but have similar levels during (CONF-730505), Augusta, GA. other months. Dreier, H.. and A. Tranquilli. 1981. 16. estimated 200-400 J. -An Reproduction, growth, distribution, and (0.2-0.4 percent of the maximum abundance of Corbicula in an Illinois cooling number present) waterfowl are killed lake. Pages S78-S9S in R. W. Larimore each fall and winter by colliding with the and J. A. Tranquilli, eds.. The Lake Sangchris study: case history of an Illinois cooling lake. power lines at Lake Sangchris. Illinois Natural History Survey Bulletin 32 (4). 17. — Body weights of mallards, Kear, 1963. The agricultural importance of wigeons, and lesser scaups bagged by J. wild goose droppings. Wildfowl Trust Annual hunters at Lake Sangchris are within the Report 14:72-77. ranges reported in the literature, ex- but Manny, B.A., R.G. Wetzel, and W.C. Johnson. cept for adult mallards of both sexes and 1975. Annual contribution of carbon, nitrogen adult female lesser scaups, are lower at and phosphorus by migrant Canada geese to a Sangchris than the mean weights hardwater lake. Internationale Vereinigung fur Theoretische und Angewandte Limnologie reported in the literature. Verhandlungen 19:949-951. 18. Mean weights of mallards bag- — Moran, R.L. 1981. Aquatic macrophytes in Lake ged early in the hunting season are Sangchris. Pages 394-412 in R.W. Larimore and significantly lower than the weights of J. A. Tranquilli, eds.. The Lake Sangchris study: case history of an Illinois cooling lake. Illinois mallards bagged late in the hunting Natural History Survey Bulletin 32(4). season. National Oceanic and Atmospheric Administra- 19. — We tentatively conclude that tion. 1974-1977. Climatological Data: Illinois. slag is not a toxicant of catastrophic pro- Vol. 79-82. portions when ingested by mallards at National Coal Association. 1974. Steam- electric plant factors (fuel consumption and costs, levels equal to or less than those admin- plant capacity, net generation, 1972, and istered during this study. However, the planned capacity 1973-1979), 1973 edition. evidence also indicates that ducks would 118 p. be better off if they were not exposed to Paloumpis, a. a., and W. C. Starrett. 1960. An slag for long periods of time. ecological study of benthic organisms in three Illinois River flood plain lakes. American 20.— The diet of mallards at Midland Naturalist 64 (2):406-4S5. Sangchris is from 88 to nearly 100 percent Sanderson, Wallace W. 1953. Studies of the com. character and treatment of wastes from duck 21. — Most or all ducks at Sangchris farms. Proceedings of the 8th Indiana Waste ingest both Corbicula shells and slag. Conference, Purdue University Fxtension Series 83:170-176. 22.— The water areas receiving Steel. R.G.D., and H. Torrie. 1960. Principles heaviest use by waterfowl may have J. and procedures of statistics. McGraw-Hill Book received as much as 65 kg of nitrogen and Company, Inc., New York, Toronto and 36 kg of phosphorus per hectare in 1 year London. 481 p. from the feces of the birds. Tranquilli, J. A., R. Kocher. and J.M. 690 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 McNuRNEY. 1981. Population dynamics of the of Sciences and National Academy of Lake Sangchris fishery. Pages 413-499 in R.W. Engineering, Washington, D.C. 594 p. Larimore and J. A. Tranquilli, eds., The Lake Webb, D.W. 1981. The benthic macroinvertebrates Sangchris study: case history of an Illinois cooling from the cooling lake of a coal-fired electric lake. Illinois Natural History Survey Bulletin generating station. Pages 358-377 in R.W, 32(4). Larimore and J. A. Tranquilli, eds.. The Lake U.S. Environmental Protection Agency. 1973. Sangchris study: case history of an Illinois cooling Water quality criteria 1972. National Academy lake. Illinois Natural History Survey Bulletin 32 (4). Distribution and Accumulation of Trace Metals at a Coal-Fired Power Plant and Adjacent Cooling Lake Kenneth E. Smith and William L Anderson ABSTRACT materials analyzed from Lake Sangchris, The distribution of 13 elements at the the fishes contained the lowest concentra- Kincaid Generating Station-Lake tions of all metals except mercury, which Sangchris complex in central Illinois was was higher in the fishes than in any other investigated by collecting and analyzing material. samples of coal, slag, fly ash, airborne INTRODUCTION particulate matter, soil, lake sediment, The burning of coal by electricity aquatic macrophytes, clams, and fishes. generating stations is one of the major Of the 2.7 million metric tons of coal uses of fossil fuel in this country. Since burned during the study, it was estimated such coal consumption amounts to that up to 97 percent of some metals con- millions of tons annually for Illinois, tained in the coal escaped the power plant and since coal contains a large of through atmospheric discharge. Consider- number potentially volatile trace elements, it is able amounts of boron, chromium, nickel, probable that large quantities of these lead, sulfur, and vanadium were deter- elements will be released to the environ- mined to be contained in the slag produc- ment. Among highly volatile elements ed by the plant. These metals can be like mercury, essentially all of the ele- leached from the slag, and the leachates ment in the coal burned would be releas- can enter Lake Sangchris. Positive cor- ed. relations were found between metal con- centrations in the airborne particulate This study was undertaken to investigate matter and the time that a sampler was the physical and biological dynamics of beneath the Kincaid Generating Station's several trace elements in Lake Sangchris smokestack plume. Significant variations and the environment surrounding the in the soil concentrations of cadmium, Kincaid Generating Station. The trace lead, and zinc were found in the elements initially selected for this study predominantly downwind direction from were arsenic (As), boron (B), cadmium the power plant. The highest concentra- (Cd), cobalt (Co), chromium (Cr), cop- tions of most metals in American pond- per (Cu), mercury (Hg), nickel (Ni), lead weed were in the discharge arm of the (Pb), selenium (Se), vanadium (V), and lake, while the highest concentrations of zinc (Zn). Coal, slag, and fly ash samples all metals were in clams collected from were analyzed for sulfur (S) by the Illinois the slag pond. Fish from the control arm State Geological Survey. Arsenic, boron, of the lake had the highest concentrations selenium, and sulfur were eliminated of metals overall, while the mercury con- from the analyses after initial findings in- centrations were quite low when com- dicated that they were below the pared with those of fish from other Il- analytical detection limits or, in the case linois lakes. Compared with other of sulfur, would require additional facilities not currently available. Dr. Kenneth E. Smith is with the Institute of Gas Technology, Chicago. Ilhnois. and William L. Anderson is with the Illinois Department of STUDY AREA Conservation. Urbana. Illinois. Lake Sangchris is an 876- ha body of This chapter submitted in March 1978. water in northwestern Christian County, 691 692 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 central Illinois. The lake was formed in lies between the west and middle arms; 1963-1966 by damming Clear Creek water is taken from the west, or intake and is used for cooling purposes by the arm, cycled through the plant, and 1,232-megawatt Kincaid Generating Sta- returned to the middle, or discharge arm. tion. Lake Sangchris consists of three The east arm is the control arm in that it long, relatively narrow arms that extend is not within the power plant's cooling southward for distances of 8.0-11.3 km loop and acts to a certain, limited extent from the dam (Fig. 1). The power plant as a control data collection area. Seven A 2 Fig. 1. —Lake Sangchris and the 7 lake sampling sites for sediments and fish (O), 18 tor aquatic macrophytes( • ), and 4 for Corbicula fluminea (U). and the 9 permanent air particulate sampling sites (). Aug. 1981 Smith & Anderson: Trace Metals 693 sampling sites were established for environmental compartments, and the sediments from Lake Sangchris (Fig. 1): remaining 3 years to the study of the Station 1 was in the intake canal of the other trace metals. Because of this power plant; stations 2, 3, and 4 were dichotomy, procedures of collection representative of the intake arm, the deep changed for some samples as our early water area near the dam, and the work showed some deficiencies. Also, the discharge arm of the lake, respectively; preparative methods used for the samples Station 5 was in the power plant's to be analyzed for mercury were often discharge canal; and Station 6 was in the different from those used for the other slag settling pond. Station 7 was in the metals because of mercury's volatility. It control arm and was not influenced by is this high volatility which allowed the the power plant's water circulation. use of the sensitive cold-vapor atomic ab- sorption Lake Sangchris' watershed covers ap- spectrophotometric (AAS) technique proximately 18,880 ha. The watershed and for mercury, while more con- ventional other land surrounding the lake are near- flame AAS methods were used for the other ly level to moderately sloping. The prin- metals. cipal soil types are Illiopolis (Sable) silty clay loam, COLLECTION AND PREPARATION adjacent to the lake and to the OF SAMPLES north of the power plant, and Virden silty clay loam, in the lake's watershed and to Coal, Slag, and Fly Ash the south of the plant (Fehrenbacher et Samples of coal, slag, and fly ash were al. 1950). These similar soil types are taken at the Kincaid Generating Station dark colored and poorly drained; they on 5-20 days each month from September developed from 1.2 to 2.1 m of loess 1973 through August 1974 by plant per- under prairie vegetation (Fehrenbacher sonnel. The coal samples were com- et al. 1967:8,10). The land is intensively posites, taken over 24-hour periods farmed, the principal crops being corn with an automatic sampling device, from (Zea mays L.) and soybeans {Glycine max coal going into storage silos within the (L.) Merr.). plant prior to being burned. Slag was taken from one of the several pipes used The Kincaid Station began generating to carry the residue slurry to the electricity for commercial consumption settling pond. Samples of fly ash were removed in 1967 and consumed 2.98 million tons from the bottoms of the precipitator hop- of coal in 1972. Upon being burned in pers. This ash had recently come out of this plant, coal is reduced to approx- the precipitators but had not entered silos imately 15 percent of its original weight. used for holding fly ash. About half the residue is slag that is slur- The coal, slag, and fly ash samples for ried and pumped into the slag pond, a each were air dried, diked area of 32 ha, containing water and month combined by type, and reduced to a manageable located immediately northeast of the size by means of a Jones sample splitter. The plant. The other half of the residue is coal samples were then ground in an primarily fly ash, 99 percent of which is air-cooled micro mill to removed from the smoke by electrostatic pass a 200-mesh sieve. portion of each precipitators on each of the plant's two, A of the monthly 168-m-high smokestacks. composite samples of slag was hand ground with a mullite mortar and pestle. Peabody Coal Company's Mine No. 10, Because of their extremely small particle a shaft (underground) mine, supplies all size, it was not necessary to grind the coal burned by the Kincaid Generating samples of fly ash. These samples were Station. The mine is 1.6 km west of the used in all subsequent analyses. power plant. METHODS Airborne Particulates In the mercury study, three samples of The first year of investigation was airborne particulate matter were col- dedicated to the study of mercury in all lected during a single 24-hour period 694 Illinois Natural History Survey Bulletin Vol. 32. Art. 4 each month from October 1973 through with a radius of approximately 6.4 km, a August 1974 (except December 1973) distance between those used in the first with BGI Model IIA high-volume air collections, and as close as feasible to samplers. Two samplers were positioned electrical service. Permanent locations approximately 5 and 10 km downwind eliminated the need to recaUbrate the and one approximately 5 km upwind samplers before every sample. Two addi- from the power plant. Since the samplers tional samplers were placed southwest of were placed under the smokestack plume the power plant to sample the air prior to on the day of sample collection, reloca- its passing the Kincaid Generating Sta- tion of the samplers was necessary for tion (Fig. 1). Samples were taken monthly each collection. This relocating in turn during a single 24 -hour period using the necessitated recalibration of the samplers same type of glass fiber mats as those after they were transported. The opera- described above. The time periods tional parameters for the air samplers are selected were based on local weather con- shown in Appendix A (Table Al). The ditions, i.e., wind from the southwest, ex- particulate matter was collected on 20.3- pected wind direction stability for 24 x 25.4-cm mats of high purity glass fiber hours, and no precipitation. Such condi- with a collection efficiency of 99.98 per- tions were found in January, April,' May, cent of 0.2-nm dioctylphthalate (DOP) June, July, August, October, and particles. After the mass of the par- November 1975. Further attempts to ticulate matter collected was determined, gather samples were terminated in the mats were cut into eight approx- February 1976. Operational parameters imately equal, wedge-shaped sections for for these samplers are also in Appendix A analysis. (Table A2). In the later collections for metals other than mercury, seven similar high-volume Soil air samplers were located permanently Samples of soil were taken at intervals of northeast of the power plant along an arc approximately 3.2 km on a square grid, Setting up a portable high-volume air sampler to measure smokestack emissions. Aug. 1981 Smith & Anderson: Trace Metals 695 Fig. 2. — Soil sampling sites (X) around Kincaid Generating Station (K), the boundary between the two primary soil types, and the radial sectors (A, B, C, and D) used for statistical analysis (see Table 8). Also shown are county boundary lines and the Springfield Power Plant (S). 38.6 km across, with the power plant at the ped with S4 kg of weights and a 61 -cm center. The sampling sites are shown in collecting tube, was used to take three Fig. 2. Sampling was limited to two close- core samples at each station, penetrating ly related soil types, Illiopolis (Sable) silty in each case into the original bottom clay loam (north of the plant) and Virden material. One such series was taken dur- silty clay loam (south of the plant). ing the first year of the project, and a sec- Samples were taken from the upper 2 cm ond series in the third year. Each core was of soil in agricultural fields that had not held intact within a plastic sleeve in- been disturbed for several months. Sub- serted into the collecting tube prior to samples were scraped from three separate taking the sample. The cores were frozen level areas at each site and pooled to for storage and to facilitate sectioning. make a single sample. The sampling sites Later, the plastic sleeve was warmed were at least 50 m (usually 100 m) from under running water, and the frozen core secondary roads and at least 200 m from was extruded. The interface between the highways and railroad tracks. The sedirnent and the original bottom samples were air dried, placed in plastic material was identified, and the sediment bottles, and rolled for 2 hours to portion was sectioned into equal parts, homogenize the soil before an aliquot was believed to represent individual years of removed for analysis. the lake's existence on the assumption of an almost constant deposition rate. There Lake Sediment were 10 sections for the 1974 collection, Sediment S2uiiples were taken from Lake and 12 for the 1976 collection. Although Sangchris with an Ekman dredge and a sediments are known to become com- Phleger corer. In the mercury study the pacted and dewatered with time, dry Ekman dredge was used at six regular lake weights of the sections indicated that the stations (the slag pond was excluded) on a consequent errors in dating the sections quarterly basis. Subsequent yearly were less than 1 year. Two additional sec- samples were taken for continued tions, the same size as those in the sedi- monitoring of the sediment's mercury ment, were cut from the upper end of the concentration. The Phleger corer, equip- remainder (original bottom material) of 696 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 the core. The lower of those two sections, monitor mercury concentrations in Lake plus the upper 9 sections of 10 or 11 of 12, Sangchris fishes. All collections of fish were kept for analysis. The mean were taken from the general areas of the thickness of sediment at the six stations established stations (Fig. 1). For purposes was 28.8 cm with a standard deviation of of comparison, largemouth bass were col- 10.7 cm for the first collection, and 33.7 lected from Lake Decatur, Otter Lake, cm mean thickness with a standard devia- and Lake Shelbyville, and black tion of 12.1 cm for the second collection. bullheads from the latter two lakes. All of these samples were analyzed only for mer- Macrophytes cury. A collection of 10-18 fish of each of the same seven species was taken in ad- For the mercury study a sample of dition to 14 carp, Cyprinus carpio, in July American pondweed (Potamogeton 1976 for analysis for other trace metals. Poir.) was collected from Lake nodosus The fish were collected primarily by elec- in 1974 at each of 18 sites Sangchris trofishing and with gill nets, as described where it grew in each of the three arms of by TranquilU et al. (1981). However, the lake (Fig. 1). In 1976 another 18 trotlines were used to collect the samples of pondweed were collected from bullheads and approximately half of the sites. all samples, the leaves the same For channel catfish. After body weight and separated and stems were and were wash- total length were recorded, muscle tissue ed with deionized water, and as much was removed from each carcass by con- surface water as possible removed was ventional filleting techniques to obtain a before they were weighed. Each sample representative sample of 100-200 g of was cut into small pieces, lyophilized for tissue from each fish. For the larger fishes 48 hours, and then pulverized in a micro (over 1 kg), the fillets were ground in a mill. food grinder and mixed thoroughly prior to the removal of a 100-200-g sample. Clams The samples were freeze dried and A sample of clam, Corbicula fluminea, pulverized in a micro mill. The carcasses was collected from each of three sites in and some livers from the fish in the initial Lake Sangchris and from the slag pond collection were treated in the same man- (Fig. 1). The clams were raked from the upper sediments along the shoreline in water ranging from 0.3 to 1 m deep. Mus- ANALYTICAL PROCEDURES cle tissue was removed from the shell, lyophilized for 72 hours, and pulverized Mercury in a micro mill. The tissue samples from the plants Fishes and animals were weighed, placed in The initial sample of fish from Lake fiasks, and digested in a mixture of Sangchris consisted of from 10 to 12 fish sulfuric acid (H1SO4), nitric acid of each of seven species: largemouth bass, (HNOj), 5-percent potassium per- Micropterus salmoides; green sunfish, manganate (KMnOi), and 5-percent Lepomis cyanellus; bluegill, L. potassium persulfate (K,S/3j) in a 95'C macrochims; white crappie, Pomoxis an- water bath for 2 hours. Standards, con- nularis; white bass, Morone chrysops; taining 0.05 A^g of mercury as a chloride, channel catfish, Ictalurus punctatus; and were carried through the digestion with black bullhead, I.melas, taken in Oc- each batch of samples. The analyses were tober 1973. Ten to 12 largemouth bass performed on an Instrumentation and similar numbers of channel catfish Laboratory model 353 atomic absorption were also collected duringjanuary, April, spectrophotometer equipped with a cold- and July 1974. Ten largemouth bass and vapor mercury analysis system. Reduc- 10 black bullheads were taken in May tion of the mercury (II) in the digested 1975, May 1976, and June 1977 to samples was accomplished with a Aug. 1981 Smith & A^^DERsoN: Trace Metals 697 Taking sediment core samples from tlie Lake Sangchhs basin for trace metal analyses. 5-percent stannous chloride (SnCli) solu- ner of the U.S. Environmental Protection tion in 4-N hydrochloric acid (HCl), as Agency's procedure (1972), but a described by Hwang et al. (1971). 30-minute treatment in a 95"C water Recovery of 0.05-/ig spikes of mercury bath was substituted for the 16-hour from samples of fish tissue was 98 ± 3 room temperature final digestion. percent by this analytical procedure. Analysis was also done by a cold-vapor Samples of National Bureau of Standards atomic absorption technique, again using Standard Reference Materials SRM 1571, a SnClj reductant added to each bottle Orchard Leaves, and SRM 1577, Bovine immediately before it was attached to a Liver, were also analyzed by this method Perkin-Elmer MAS-50 mercury analyzer. and gave results within the limits provid- Because of the previous boil-off of ed in the NBS certificate of analysis for HNOsi fumes, little background was both SRM materials. found when blanks were run. The soil, sediment, and air filter The mercury in the coal, slag, and fly samples were digested following the pro- ash samples was liberated by a high- cedure of Jacobs & Keeney (1974) with a temperature volatilization technique, few simple modifications. The samples since the digestion methods described were digested in BOD bottles in the man- previously did not give satisfactory 698 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 results. The coal, slag, and fly ash acid (HBOj). Standards were made in a samples all left residues when analyzed by matrix containing 300 ppm aluminum these open digestions. In the procedure (Al), 35 ppm potassium (K), 30 ppm adopted, 0.5-g samples were weighed into sodium (Na), and 10 ppm magnesium porcelain combustion boats, which were (Mg) to approximate the content of these then placed in a Vycor tube and heated minor elements in the samples. furnace. Oxygen was to 600°C with a tube For analyses of the boron in the coal over the hot sample at the rate of passed and fly ash samples, a sodium carbonate ml/min. The end of approximately 50 (NajCOs) fusion was perfomed in from the sample the tube downstream platinum crucibles. The cooled melt was silver wool was connected to a leached with warm water and then amalgamator (Long et al. 1973) to collect analyzed spectrophotometrically using minutes the volatilized mercury. After 30 carminic acid (Hatcher & Wilcox 1950). collector removed and quan- the was Slag was not analyzed for boron, since its titatively analyzed in an apparatus high iron content would contaminate the similar to that of Long et al. (1973). platinum crucibles, rendering them useless for further work. Coal, Slag, and Fly Ash Airborne Particulates The sample digestion techniques used for the determination of arsenic (As), boron The soiled filter mats from the air (B), cadmium (Cd), cobalt (Co), particulate sampling were returned to the chromium (Cr), copper (Cu), nickel (Ni), laboratory and weighed to determine the lead (Pb), selenium (Se), vanadium (V), amount of particulate matter collected. and zinc (Zn) were quite similar except They were then quartered, and one- for the starting material. For coal, high quarter of each sample was used in the temperature ash (HTA) was used for the analysis. The section was cut into small determination of boron, cadmium, pieces and extracted with a mixture of cobalt, chromium, copper, nickel, lead, 0.05-N HCl and 0.025-N H1SO4. Forty- vanadium, and zinc, while low five ml of this extracting solution were temperature ash (LTA) was used for the used for each quarter sample analyzed. determination of arsenic and selenium. The mixture of the small pieces of the The HTA was prepared by igniting coal filter media and the extracting solution samples for 14 hours at bbO'C in was shaken vigorously for 2 hours on a platinum (Pt) crucibles in a muffle fur- mechanical shaker. Afterwards, the solu- nace. The LTA was prepared by Dr. H. tion was filtered into a 100-ml volumetric (Illinois State deionized J. Gluskoter's laboratory flask and made to volume with Geological Survey) by means of micro- water. Standards for comparison during wave pljisma ashing at a temjjerature never analysis were made in the same concen- exceeding 150°C. Slag and fly ash were trations of extracting solution. To test the dried and then used directly for trace recovery efficiency, 8- x 8-cm squares of metals analysis. clean filter media were treated with a containing 5 of each of the Digestion of the coal, slag, and fly ash solution fig metals being analyzed. After air drying, samples for cadmium, cobalt, chromium, these squares were extracted by the same copper, nickel, lead, vanadium, and zinc method that was used for the samples col- was performed in a Parr 4745 acid diges- lected in the field. Analyses of the squares tion bomb using aqua regia (1 part HNOs gave results ranging from 86 to 110 per- to 3 parts HCl) and hydrofluoric acid recovery for the seven metals placed (HF). The technique follows that of Ber- cent on the mats. nas (1968) and Hartstein et al. (1973) with minor modifications to fit available Soil and Sediment equipment. After 4 hours at lOCC, the bomb was cooled and opened, and the re- Soil analyses were made to determine maining HF was complexed with boric the quantities of trace elements Aug. 1981 Smith & Anderson: Trace Metals 699 associated with the soils, not the total ca- ment and the amount of coal consumed tion m9keup of the soil. Therefore, it was monthly. To arrive at comparable figures decided to analyze the cations extract- for slag and fly ash, the monthly coal con- able by a dilute acid mixture of sumption was multiplied by 0.075, based 0.05-N HCl andl0.025-N HjS04 (1:1, on the assumption that the 15-percent v: v), using 5 g of soil shaken with 20 ml of solid residue of coal burning is equally this mixture for 1 hour. The sample was divided between slag and fly ash. The then centrifuged for 10 minutes at 20,000 15-percent solid residue value was obtain- rpm, the supernatant was filtered, and ed from the operating personnel at the the resulting solution was analyzed direct- Kincaid Generating Station, and it agrees ly by atomic absorption spec- quite well with those obtained by Klein et trophotometry. al. (1975) of 8.5 percent for slag and 4.8 percent for fly ash at the Allen Power Macrophytes, Clams, and Fishes Plant in Memphis, Tennessee. The prod- ucts of the 0.075 value The digestion procedure used for the and the concen- trations of each element yielded the macrophytes, clams, and fishes was calculated total amounts of the elements begun with a 500°C overnight ashing in a in the slag muffle furnace and treatment with 5 ml and fly ash. the destruction of of HNOj to complete The yearly amounts of trace elements all organic material. The sample was calculated from the total amount of coal dryness on a hot plate, then taken to burned by the Kincaid Generating Sta- covered, and returned to the BOO^C muf- tion are summarized in Table 5. The fle furnace for approximately 20 minutes. amounts shown for atmospheric It was then treated with 5 ml of HCl to discharge are simply 1 percent of the solubilize the resultant solid, refluxed on figures for fly ash (this procedure assumes the hot plate until the sample had dissolv- electrostatic precipitation efficiency of diluted to volume in a 100-ml ed, 99 percent) and do not take into account volumetric flask, and analyzed by atomic the relationship of concentration to parti- absorption spectrophotometry. cle size (described below). Therefore, they represent the lower limits of possible RESULTS AND DISCUSSION atmospheric discharge. The exception to COAL, SLAG, AND FLY ASH this procedure is mercury, which is shown as the total difference between the coal Concentrations of trace elements found value and the slag and fly ash values. in the coal, slag, and fly ash are shown in al. al. Tables 1, 2,' and 3, respectively. The Davison et (1974), Natusch et values for arsenic and selenium are given (1974), and Klein et al. (1975) classified the elements in their investigations as less than the limit of detection, since it ac- was not possible to detect them with the cording to their relative volatilities and techniques used. The amounts of trace associated recondensations on particulate metals in coal from a given coal seam material. Natusch's and Davison's vary widely. The mean values obtained mechanism explained size-concentration for our samples compared quite well with behavior for many elements. Those that on values presented by Ruch et al. (1974), elements accumulate the smaller samples C-14838 and C-17016, as shown fly ash particles are assumed to be volatile in Table 4. at the temperature of combustion In an attempt to obtain a mass (ISOO'-ieOO^C); as the flue gas cools, balance on some of the trace elements in the volatiles condense on or are adsorbed the coal as it passed through the Kincaid on the fly ash. Since condensation and Generating Station, the concentrations adsorption are surface phenomena, the found in the coal, slag, and fly ash were concentration of condensed elements mathematically converted to total should be inversely proportional to parti- amounts. This was done by finding the cle size. Those elements not volatile in the product of the concentration of an ele- combustion zone form the fly ash par- I 700 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 lO ^ Ol -"T kD t^ id lO o S 55 be Smith & Anderson: Trace Metals 701 CO O T3 702 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 O OJ S 55 o O Ml Aug. 1981 Smith & Anderson: Trace Metals 703 Table 4. —Comparison of trace element concentrations in coal as analyzed by Illinois State Geological Survey (ISGS) and the present study. Concentration (mk/R whole coal) Element Present Study ISGSa Arsenic 704 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 intolerable, but can be explained. The Table 7, —Concentrations of total mercury (fig Hg/g dry particulate matter) in airborne soil type, which exists primarily to Virden particulate matter collected in the vicinity of the the south of the power plant, is higher in Kincaid Generating Station. trace metals than the Illiopolis soil to the north of the plant. The samplers at sta- tions 8 and 9 were immediately north of land cultivated for farming and were ex- posed to high levels of dust from this soil. All other samplers had been located in pastures or other grassy fields at least 500 m from cultivated fields that could pro- duce dust. Undoubtedly all samples did in- clude some dust from nearby soils, but it is felt that those downwind from the plant were significantly influenced by the plant's smokestack effluent. The mean values calculated, excluding the station 8 and 9 data, are summarized in Table 6. Since only one sample was collected at each site during each sampling period, it was not possible to apply statistical tests based on means and deviations to the data. However, the data were subjected to a multiple regression analysis that also used a sample collection date, location, average air flow, and time under the smokestack plume as dependent variables. The test was designed to deter- mine whether the variations in metal con- centrations could be accounted for by these variables. The multiple regression coefficients calculated for cadmium, chromium, copper, nickel, and zinc were highly significant at the P <0.01 con- fidence level. No significant correlations were found with fewer dependent variables. This fact allows us to conclude that the variations observed in the amounts of the metals collected can be related to these Table 6. —Mean concentrations of trace metals (^g/g) in the airborne particulate matter collected in the vicinity of Kincaid Generating Station in 1975. Month Aug. 1981 Smith & Anderson: Trace Metals 705 Air Weather Service of the U.S. Air Force rotated through 180° to better illustrate (1963) for the 10-year period from 1953 a resulting fallout pattern. That is, the through 1962 indicate a strong southerly compass headings on the map show the wind flow, with winds from the northwest directions the winds were blowing toward, making an important but lesser contribu- and not the directions they came from. tion. These data are illustrated in Fig. 3. The contours indicate the percentages of The traditional wind rose has been the winds that blew in the directions in- Fig. 3. —Wind distribution around ttie Kincaid Generating Station (K). Each contour line denotes the percentage of total wind observations (87.225) having the velocity indicated by its distance from the power plant. 5 10 I I I Wind Speed (km/h) Fig. 4. — Distribution of cadmium (|jg/g) in the soils surrounding the Kincaid Generating Station. 706 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 dicated on the map and that had a wind speed is indicated by the distance on the speed equal to the distance from the Kin- map between the 6-percent area and the caid Generating Station. For example, Kincaid Station (see scale). the area to the north of the Kincaid Sta- The results of the soil analyses are tion labeled 6 indicates that 6 percent of presented in Fig. 4-11. The isograms of the winds observed blew to the north at a these figures denote equal concentrations speed of approximately 15 km/h. The of each given element. The isograms were Fig. 5. — Distribution of chromium (^ig/g) in the soils surrounding the Kincaid Generating Station. Fig. 6. — Distribution of cobalt (Mg/g) in the soils sur- rounding the Kincaid Generating Station. Aug. 1981 Smith & Anderson: Trace Metals 707 Fig. 7. — Distribution of copper iiuglg) in the soils sur- rounding the Kincaid Generating Station. Fig. 8, — Distribution of lead {^^glg) in the soils sur- rounaing the Kincaid Generating Station. plotted using the Illinois State Geological of the parameters whose positions are Survey's "lUimap" program package, shown by the plotted points, when the which also calculated the contour lines. values represent elemental concentra- This set of programs was developed to tions, soil composition percentages, or plot positions of geological features on a other continuously variable parameters. map of Illinois or a portion of it. Illimap This interpolation results in constant programs can interpolate between values value contour lines, which can also be 708 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 plotted on the map. The data for the among mean sample concentrations from mercury in soil were not sufficiently the two soil types shows significant dif- coherent for the computer to plot a map ferences of cobalt, copper, lead, and zinc and have thus been omitted. at P<0.01. However, for these elements Interpretation of the results of the soil the higher mean value occurred for the analyses is difficult at best and is com- Virden soil, which occurs primarily to the plicated by the occurrence of two soil types south of the power plant. Yet the wind in the study area. Analysis of variance data indicate that the majority of the par- Fig. 9. — Distribution of nicl Fig, 10 — Distribution of sulfur (Mg/g) in ttie soils sur- rounding ttie Kincaid Generating Station. Aug. 1981 Smith & Anderson: Trace Metals 709 Fig. 11. — Distribution of zinc (mQ/Q) in the soils sur- rounding the Kincaid Gener- ating Station. dculate fallout from the power plant Table 8. — Radial variation of concentrations of cadmium, lead, and zinc (^ig/g dry soil) in should be to the north of the plant. Illiopolis silty clay loam with the Kincaid Generating Station at the center. Underscored To evaluate the radial distribution of means do not differ significantly when tested by trace metals in the soil, it was assumed Duncan's multiple range test. that Kincaid Generating Station was a Radial Sector * point source emitter. Then, on a radial basis, approximately equal areas of land were partitioned (Fig. 2) and an analysis of variance was made between those areas. Statistically significant (P< 0.05) variations were found for cadmium, lead, and zinc in the Illiopolis soil. For all three elements the area with the highest mean value was closest to the plant, the second highest value was the farthest sector, the third highest in the next-to-outermost ring, and the lowest in the next-to- innermost ring. The application of Dun- can's multiple range test showed the sam- ple from the 0.97-km radius section was significantly different from the outer two areas in all cases (Table 8). The higher values on the inner ring reflect the deposition of the relatively heavy par- ticulate matter escaping the stacks. The remaining material is carried farther from the plant before deposition. This finer material contains much higher con- centrations of metals (Natusch et al. 1974) and thus has a greater influence when it is incorporated into the soil. 710 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 9. — Lake Sangchris sedimentation rates as determined from core samples in September 1973 and 1975 (see Fig, 1 for sampling sites). Aug. 1981 Smith & Anderson: Trace Metals 711 712 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table 11. —Mean concentrations of trace metals (»jg/g dry sediment) in sediment core sections from Lake Sangchris (see Fig, 1 for sampling sites). Values followed by ttie same letter do not differ significantly from each other, each column separately, when tested by Duncan's multiple range test at P<0.05, Station Cd Cr Co Cu _H£_ Pb Zn 0.17a Aug. 1981 Smith & Anderson: Trace Metals 713 2. Table 1 —Concentrations of total mercury (>ig/g dry sediment) in samples of the upper 1 cm of sediment from Lake Sangchris (see Fig. 1 for sampling sites). Values followed by tfie same letter do not differ significantly from eacfi other wfien tested by Duncan's multiple range lest at P<0.05. Sampling 714 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 14) show that the highest concentrations were in the samples from the slag pond. When tested by one-way analysis of variance, significant variation was found o for every element except zinc. Applica- Q. O) tion of Duncan's multiple range test to OS the other data showed that in every case the values from the slag pond samples varied significantly from the other samples, which did not vary from one another. Pringle et al. (1968) concluded that for C/3 several species of estuarine mollusks the <1> accumulation rates for trace metals are dependent upon the environmental con- centration, the temperature, and the time of exposure. It seems reasonable that the aquatic environment present in the slag pond would be higher than other to in trace elements due to the proximi- 0) sites c ty of the slag which is being constantly I leached by the slurry water. In this en- TO vironment clams might accumulate much "3 o higher concentrations of these metals S o than would clams exposed to water o several miles down the discharge arm. In the course of their movement out of the slag pond and around the cooling loop, the concentrations of metals leach- ed from the slag pond become greatly diluted and may be attenuated by ab- sorption by the bottom sediments or by other aquatic organisms. Dreesen et al. (1977) have shown that chromium and vanadium are solubiliz- ed in ash pond effluent, while zinc is not significantly increased. High values were found for both chromium and vanadium in Kincaid Generating Station slag, but zinc was preferentially partitioned into the fly ash (Table 5). The data for metal concentrations in clams reflect the trends suggested by Dreesen et al. (1977) and the slag analyses (Table 2); i.e., chromium O M and vanadium were concentrated to a much greater extent than zinc in the clams from the slag pond when compared with clams from other parts of the lake (Table 14). \ug. 1981 716 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 FISHES It was found that concentrations of A summary of the species, numbers, mercury in the largemouth bass and black dates of collection, mean weights and bullheads from the other lakes in central mean lengths of fishes analyzed in this Illinois were as high as or higher than in the study is given in Table 15. Those col- concentrations bass and bullheads lected in October 1973 were analyzed for from Lake Sangchris (Table 18). The total mercury concentrations in the mean concentration for bass from Lake fillets, carcasses, and whole fish (Table Sangchris was only about one-half of that 16). Mean concentrations of mercury for bass from Lake Decatur, one-third of were consistently higher in the fillets than that for bass from Otter Lake, and one- in the carcasses or the entire fish. The eighth of that for bass from Lake bulk of the mercury present in fish was in Shelbyville. The highest mercury concen- organic forms (Kamps et al. 1972, Rivers tration in bass from Lake Sangchris (0.15 et al. 1972), which have an affinity for /ig/g) was less than the lowest concentra- tion protein, and therefore it is not surprising found in bass from Lake Shelbyville that the highest values detected in fish (0.23 /ug). The lowest concentration from Lake Sangchris occurred in the determined for bass from Lake Decatur muscle tissues (fillets). Consequently, was 0.11 Mg/g- The concentrations of black bullheads and largemouth bass col- mercury were, at first, considered to be lected on dates later than October 1973 atypically low for central Illinois bass were analyzed only for the total mercury (Anderson & Smith 1977). However, our concentrations in their fillets (Table 17). latest sample, taken in June 1977 (Table The data for largemouth bass were sub- 17), shows a value more in line with those jected to an analysis of variance, using of bass from other lakes although the the weight and length of each fish as mean weight of Lake Sangchris bass is covariants, since significant correlation higher than the mean weights of bass has been found at P<0.05 between the from other lakes. total mercury concentration and the size Mercury concentrations in bass collected of the fish. The results showed a signifi- after 1974 show that the wide gap be- cant variation in the mercury concentra- tween mercury levels in Lake Sangchris tions in the fillets from 1973 to 1976. The bass and those of bass in other lakes has amount found in the 1975 sample, 0.26 closed noticeably. The mean concentra- IJg/g, was significantly different from all tion of mercury in bass from Lake other means when tested by Duncan's Sangchris (0.18fig/g, the mean of 1975, multiple range test as modified by 1976, and 1977) (Table 17) is between the Kramer (1956). No reason can be means for Lake Decatur and Otter Lake postulated for this sample's being higher bass but is still less than one-third of the than all the others. No significant varia- Lake Shelbyville bass mean concentra- tion in the concentrations observed in tion. The mean mercury concentration in black bullheads was found over the study black bullheads from Lake Sangchris period. (O.lO^g/g) is still approximately one-half 6. of fishes collected Table 1 —Concentrations of total mercury ( uglg wet tissue) In seven species from Lake Sangchris during October 1973. Aug. 1981 Smith & Anderson: Trace Metals 717 Table 17. —Mean concentrations of total mercury (^g'g wet tissue) in the fillets of largemouth bass and black bullheads from Lake Sangchris. Collection Dates Number Total Mercury Largemouth Bass Oct. 1973 12 0.063 Jan. 1974 10 0.053 Apr 1974 12 0.089 July 1974 10 0.089 May 1975 15 0.26 May 1976 12 0.13 June 1977 12 0.13 Black Bullheads Oct. 1973 10 0.16 Sept. 1974 U 0.093 May 1975 15 0.12 May 1976 11 0.079 June 1977 11 0.079 the concentration found in bullheads (8.23 Mg/g) ''nd carp (7.22 ;^g/g) were from Lake Shelbyville and Otter Lake. not statistically different from those in other species. Fillets of fish collected in July 1976 were analyzed for cadmium, cobalt, Attempts to correlate the various meted chromium, copper, nickel, lead, concentrations with the weight or length vanadium, and zinc (Table 19). Analyses of the individual fish yielded significant of variance performed on data grouped (P<0.05) positive correlations only for by species shovifcd that there was signifi- cadmium in white bass; mercury in black cant variation at P<0.01 in the cobalt bullheads, largemouth bass, and white and zinc concentrations. Further analysis bass; and lead in white bass. Atchison et by Duncan'smultiple range test (Kramer al. (1977) were not able to relate cad- 1956) showed that for cobalt only the mium, lead, or zinc concentrations to the mean concentration in carp (0.067 Mg/g) sizes of bluegills analyzed in their study was significantly higher than that in on Indiana lakes. When the results of the green sunfish (0.010 Mg/g)- Fo"" zinc, a current study were grouped by the arm of similar analysis showed that the mean the lake from which fishes had been col- concentration in black bullheads (9.79 lected and analyses of variance were per- Mg/g) ^^^ significantly greater than the formed, significant (P<0.05) variation mean concentrations in channel catfish occurred for nickel in bluegill; cobalt, (6.85 Mg/g). green sunfish (6.96 /. Table 18. —Comparison of the concentrations of total mercury (>ig/g)wet tissue) in the fillets of largemouth bass and black bullheads from Lake Sangchris and other lakes in central Illinois. 718 Illinois- Natural History Survey Bulletin Vol. 32, Art. 4 Table 19. —Mean concentrations of trace metals (A^g/g wet tissue) in fishes trom Lake Sangchris. Aug. 1981 Smith & Anderson: Trace Metals 719 quently in fish from the control arm. The outright rejection of these metals by the highest mean values occurred in bluegill clams. For mercury, the omnivorous and white crappie from the discharge fishes (0.12 Mg/g) contain higher concen- arm; in the black bullheads from the in- trations than the piscivorous fishes (0.072 take arm; and in carp, channel catfish, fjg/g), a reversal of the trend of bioac- and largemouth bass from the control cumulation noted by Cumbie (1975), arm. For green sunfish and white bass the D'ltri (1972) and Potter et al. (1975). The highest overall means were evenly divided slightly basic pH of Lake Sangchris between the discharge and control arms (Brigham 1981) may be the major factor and the intake and discharge arms, in the overall low accumulation of mer- respectively. In total, of 64 possible cury, as more acid waters are considered means the highest values occurred in the to favor mercury accumulation by fish intake arm 14 times, in the discharge arm (Nelson et al. 1971). Gillespie (1972) has 21 times, and in the control arm 29 times. shown that g^ppies (Poectlia reticulata) The lowest values occurred 34 times in accumulated up to 0.9 Mg/g of total mer- the intake arm, 19 in the discharge arm, cury when exposed to lake sediments con- and 1 1 times in the control arm. Since the taining 0.15 Mg/g of mercury over a control arm is not in the predominant 140-day period. Gillespie also noted that wind drift pattern from the plant and mercury mobilization in guppies from in- since it is not influenced by the circula- dustrial sediments with low mercury con- tion pattern of the lake, the higher values centrations is much higher than from observed in fish from this arm have prob- lake sediments with higher mercury con- ably been caused by some other source. tents. Since the sediments of Lake Mean values were calculated for the Sangchris contain relatively low mercury trace metal concentrations in the concentrations, little mercury mobiliza- sediments, aquatic macrophytes, clams, tion would be expected in this lake. omnivorous fishes and piscivorous fishes, respectively (Table 21). It can be seen SUMMARY that, for all metals except mercury and chromium, lake sediments contain the The vapor emissions, untrapped by highest or second highest concentrations ash, and the accumulated slag from the Kincaid Generating Station contributed of all materials analyzed. The aquatic macrophytes accumulated higher con- significant amounts of chromium, cop- per, mercury, and sulfur to the surround- centrations of cobalt (2.91 Mg/g) snd lead ing land, including the (5.02 /ug/g) than did the sediments watershed of Lake Sangchris, and to the lake itself. (1.92 and 1.91 Mg/g). while the clams had higher concentrations of copper Smaller amounts of boron, cobalt, and nickel also are emitted by the same (4.54 f.(g/g) and zinc (36.2 Mg/g) than sources. Airborne particulate sample had the sediments (1.96 and 16.7 Mg/g)- analysis indicated a relationship to the For metals other than mercury, the smokestack emissions of the power plant. fishes of Lake Sangchris in general contain Smokestack emissions also seemed to lower concentrations than do the other deposit cadmium, lead, and zinc on the materials tested. However, chromium soils downwind from the plant. and nickel concentrations in clams are lower than those in fish and indicate In the lake itself, sediment trace metal Table 21. —Mean trace metal concentrations (|ig/g ) in five components of Lake Sangchris. Component Cd Co Cr Cu JlS_ Ni Pb Zn Sediments 720 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 from a coal-fired power plant. Environmental concentrations tended to be higher in the Science and Technology 10:1017-1018. discharge arm or dam sampHng sites. Dreher, G.B., C.B. MicHMORE. and D.W. highest trace metal values in The Stover. 1977. Major, minor, and trace elements the aquatic macrophytes were also found of bottom sediments in Lake Du Quoin. Johnston in samples from the discharge arm except City Lake, and Little Grassy Lake in Southern Il- State Geological Survey En- for mercury, of which the intake-arm linois. Illinois vironmental Geology Note 82. 37 p. samples contained the highest levels. Fehrenbacher, J.B., R.S. Smith, and R.T. Concentrations of trace metals in clams Odell. 1950. Christian County soils. University proximity of a were related to the close of Illinois Agricultural Experiment Station Soil source of water-soluble metal con- Report 73. 64 p. taminants in the slag pond. Only cad- GO. Walker, and H. L. Wascher. University of Illinois, Col- mium and lead in white bass and mercury 1967. Soils of Illinois. lege of Agriculture. Agricultural Experiment Sta- in black bullheads, largemouth bass, and tion Bulletin 725. 47 p. white bass were positively correlated with Gillespie, DC. 1972. Mobilization of mercury whose concentra- fish size. For fish species from sediments into guppies (Poealia reticulata). tions varied by the location of collection, Canada Fisheries Research Board Journal those collected in the control arm had the 29:1035-1041. W. Freedman. and D.W. highest concentrations. The mercury Hartstein, A.m.. R Platter. 1973. Novel wet-digestion procedure concentrations in all fishes seemed for trace-metal analysis of coal by atomic absorp- the lack of mercury atypically low, but tion. Analytical Chemistry 45:61 1-614. be due to the high pH accumulation may Hatcher, J.T.. and L.V Wilcox. 1950. of the lake's water. Colorimetric determination of boron using car- mine. Analytical Chemistry 22:567-569. Hwang, J.Y., PA. Ullicci. and A.L. Malenfant. 1971. 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Toxic Aug. 1981 Smith & Anderson: Trace Metals 721 tial concentration in respirable particles. Science volatile trace elements in coal: a final report Il- 183:202-204. linois State Geological Survey Environmental Nelson. N.. T. C. Byerly. A. C. Kolbye. Jr.. Geology Note 72. 96 p. L.T. KuRLAND, R.E. Shapiro. S.I. Shibko. W.H. Steele. R. G. D., and J. H. Torrie. 1960. Stickel, J.E. Thompson. LA. Van Den Berg, Principles and procedures of statistics, with and A. Weissler. 1971. Hazards of mercury. En- special reference to the biological sciences. vironmental Research 4:1-69. McGraw-Hill Co., New York. 481 p. Potter, L.. D. Kmo, and D. Standiford. 1975. Tranquilli, J.A.. R.KocHER, andJM. McNi^rney. Mercury levels in Lake Powell: Bioamplification 1 981 . Population dynamics of the Lake Sangchris of mercury in man-made desert reservoir. En- fishery. Pages 413-499 in R.W. Larimore and vironmental Science and Technology 9:41-46. J. A. Tranquilli. eds.. The Lake Sangchris study: Pringle, B.H . D E. HissoNC. EL. Katz, and case history of an Illinois cooling lake. Illinois S.T, MuLAWKA. 1968. Trace metal accumulation Natural History Survey Bulletin 32 (4). by estuarine moUusks. Sanitary Engineering Divi- US. Air Force Air Weather Service. 1963. sion Journal. American Society of Civil Engineers LIniform summary of surface weather observa- Proceedings 94:455-475. tions. Springfield, 111. Jan. 1953- Dec. 1962. Data Rivers. J.B., J.E. Pearson, and CD. Shultz. Processing Division. Climatic Center. Asheville, 1972. Total and organic mercury in marine fish. N.C. Bulletin of Environmental Contamination and U.S. Environmental Protection Agency. Toxicology 8:257-266. 1972. Mercury in sediment (cold vapor techni- RiicH, R.R.. H.J. Gluskoter, and N.F. Shimp. que). Analytical Quality Control Laboratory, 1974. Occurrence and distribution of potentially Cincinnati, OH. Mimeographed. 8 p. 722 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 APPENDIX A AIRBORNE PARTICULATE SAMPLING Table A1. —Operational parameters for the high-volume air samplers used to collect airborne particulate matter in the vicinity of the Kincaid Generating Station for total mercury analysis. 1973-1974. Weight in mg Time of Operated Mean Particulates Date Location in Minutes Air Flow in m^/njin Collected 12 Oct. 1973 Aug. 1981 Smith & Anderson: Trace Metals 723 Table A2, —Operational parameters for high-volume air samplers used to collect airborne particulate matter in the vicinity of the Kincaid Generating Plant in 1975. 724 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 dry particulate matter) in the airborne Table A3 —Cadmium concentrations ( ^9 Cd/g particulate matter collected in the vicinity of the Kincaid Generating Station in 1975. Station^ Aug. .1981 Smith & Anderson: Trace Metals 725 Table A6.—Copper concentrations ( ^ig Cu/g dry particulate matter) in the airborne particulate matter collected in the vicinity of the Kincaid Generating Station in 1975. Station^ 726 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table A8. — Lead concentrations (i^g Pb/g dry particulate matter) in the airborne particulate nnatter collected in the vicinity of the Kincaid Generating Station in 1975. Station^ }an. Apr. May June July Aug. Oct. Nov. Mean 1 4.620 Aug. 1981 Smith & Anderson: Trace Metals 727 APPENDIX B SEDIMENT CORE SAMPLES Table B1. —Cadmium concentrations {pgCdIg dry sediment) in sediment core sections taken from Lake Sangchris in September 1975 (see Fig. 1 for sampling sites). Values underlined by the same type of line do not differ significantly from eacti ottier, eactn row taken separately. Values followed by ttie same letter do not differ significantly from eacfi ottier, eacti column taken separately. All values tested by Duncan's multiple range test used P <0.05. Station Approximate Year of Deposition 728 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table B3. —Cobalt concentrations Og Co/g dry sediment) in sediment core sections taken from Lake Sangchris in September 1 975 (see Fig. 1 for sampling sites). Values underlined by the same type of line do not differ significantly from eacti ottier, each row taken separately. Values followed by the same letter do not differ significantly from each other, each column taken separately. All values tested by Duncan's multiple range test used P <0.05- Aug. 1981 Smith & Anderson: Trace Metals 729 in Table B5- — Lead concentrations ( tug Pb/g dry sediment) sediment core sections taken from Lake Sangchris in September 1 975 (see Fig. 1 for sampling sites). Values underlined by tfie same type of line do not differ significantly from each other, each row taken separately. Values followed by the same letter do not differ significantly from each other, each column taken separately. All values tested by Duncan's multiple range test used P<0.05. 730 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Table B7. — Nickel concentrations (mS Ni/g dry sediment) in sediment core sections taken from Lake Sangchris in September 1 975 (see Fig, 1 for sampling sites). Values underlined by the same type of line do not differ significantly from each other, each row taken separately. Values followed by the same letter do not differ significantly from each other, each column taken separately. All values tested by Duncan's multiple range test used P<0.05. INDEX Air samplers, 694 reproduction, 439 Algal communities (see Phytoplankton) seasonal concentration, 432 Andenon. William L.. 656, 691 spawning concentration, 425-424, 444, 548 Antimycin-a {see Fish, standing crop) spawning time, 439 Aquatic macrophytes tagging with anchor tags, 537 biomass. 396 trace metals, 696, 715-717 common species weight-length relation, 456-457 Nelumbo lutea. 396-411 Bass, yellow (see also Larval fishes) Polamogeton nodosus, 396-411, 681, 713 condition factor, 458 community development, 400-401 entrained (see Morone) growth, 403-406 food habits, 500, 509-512 immigration/extinction rate, 401 growth, 452 leaf measurements, 396, 40S impinged, 635-636, 639-640 nutrients, 335 parasites and disease, 462 soils, relation to, 395-396 seasonal distribution, 427-430 spatial distribution, 397-400, 406-407 weight-length relation, 456-457 species, 398 Benthic macroinvertebrates (see also Corbicula; tissue analysis, 396, 408 Food habits, fishes) trace metals, 699 bathymetric distribution, 371 water temperature, 402 biomass, 370 waterfowl, food, 680-681 dominant species, 369 Arsenic seasonal abundance, 366 analysis, 698 spatial distribution, 372 concentrations in fly ash, 700-702 taxa, 363 Asiatic clam (see Corbicula) Bergmann, Harry, 615 Bass, largemouth (see also Fish tagging. Growth, Biomass (see also Fish, standing crop) Larval fishes. Movements) aquatic macrophytes, 396 average daily movements, 567-568 benthic macroinvertebrates, 370 behavior, 559 zooplankton, 342, 355-356 condition factor, 449 Blooms (see Phytoplankton, periodicity) distance traveled, 567 Bluegill (see also Larval fishes, Lepomis) gonad maturity, 440-441 condition factor, 455-459, 460 gonosomatic index, 440-443 entrained (see Entrainment) growth, 522-528, 453-454 (see also Growth, fifhingfor. 599-604, 609, 611, 613-614 fishes) food habits, 500, 512-517 fishing for, 599-606 food of largemouth bass, 529-532 food habits, 500, 502-505, 518-534 (see also growth, 452-453 Food habits, fishes) impinged, 635-636, 640 impinged, 635-636, 640 parasites and disease, 462-46S maximum range, 567 relative abundance, 452 migration, 571, 573, 582 trace metals, 696, 715-716 movements in relation to weight-length relation, 456-458 depth, 577 Boron seasons, 567, 573 analysis, 698 sex, 567 concentrations in fly ash, 700-702 thermal zones, 562-567 Bullhead, black parasites and disease, 462-463 impinged, 635, 637, 641 preferred temperature, 562, 569-571. 573, trace metals, 696, 715-717 588-592 Bullhead, yellow, impinged, 635, 637, 641 reproduction, 439, 441 Cadmium seasonal distribution, 427-430 concentrations spawning time, 439, 441-444 airborne particulates, 704, 724 tagging with anchor tags, 537 American pondweed, 715 thermoregulation, 585-592 coal, 703 trace metals. 696, 715-717 Corbicula /luminea, 713 weight-length relation, 449, 456-457 fly ash, 700-702 Bass, white (see also Fish tagging. Larval fishes) sediment. 710, 727 entrained (see Morone) distribution in soils, 705, 709 fishing for, 599-604. 606. 608-609 Carp (see also Fish tagging. Growth, Movements) growth, 453 fishing for, 599-604, 606, 610-611 impinged, 635-636, 640 growth, 451 parasites and disease. 462 impinged, 635, 637. 641 731 732 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 parasites and disease, 462 concentrations pesticide residues, 440-441, 447-448 airborne particulates, 704, 725 preferred temperature, 588-592 coal, 703 reproduction, 439-440, 445-448 Corbicula fluminea, 713 spawning time, 4S9, 445 fly ash, 700-702 tagging with anchor tags, 537 sediment, 710, 728 thermoregulation, 585-592 distribution in soils, 707 trace metals. 440. 696, 715 Corbicula (see also Benthic macroinvertebrates) weight-length relation, 456-457 age, 387-388 Catfish, channel first appearance in Lake Sangchris. 378 entrained, 648-649 food of freshwater drum, 501, 508 fishing for. 599-604. 606-607 growth food habits. 500. 505-507 annual. 381-382, 384-385 growth. 454-455 monthly, 387-388 impinged. 635. 637. 641 mortality parasites and disease. 462 predation by fish, 390-391 reproduction, 425, 432 predation by waterfowl, 391 seasonal concentration, 342 temperature induced, 385 thermal preferendum, 432 population density, relation to trace metals, 696, 715-716 depth, 382, 388-390 weight-length relation, 456-457 generating station, 382. 388, 391-392 slag pond, 382, 390 Catfish, flathead substrate, 382, 388-389 entrained, 648-649 thermal gradient, 390 impinged, 635, 637, 641 spawning season, 379-381. 382-384 Chaoborus punctipennis, 358, 363, 369, 371 trace metals, 696, 699, 713-714 Chironomidae waterfowl food, 659, 680 food of freshwater drum, 508 Corbicula fluminea (see Corbicula) food of largemouth bass. 529-533 Corbicula manilensis (see Corbicula) food of yellow bass, 510-511 Crappie, white Chironomus attenuatxis, 363, 369, 370, 372 fishing for, 599-604, 609. 611-612 Chlorine (see Fish kills) impinged, 635-636, 640 Chromium parasites and disease, 461-463 analysis, 698 trace metals. 696. 715-716 concentrations Creel census (see also Fishing) airborne particulates. 704. 724 methods, 594-597 coal. 703 objectives, 594 Corbicula fluminea, 713 Cryptochironomus fulvus, 363. 369. 370 fly ash, 700-702 Cyprinus carpio (see Carp) sediment, 710, 727 Disease (see Fish, parasitism and disease) distribution in soils, 706 Dorosoma cepedianum (see Shad, gizzard) Clams (see Corbicula) Dreier. Herbert, 378. 594 Climate, 286 (see also Water quality) Drum, freshwater Coal entrained, 648-651 amount burned, 723 food habits, 500. 507-509 analysis, 696 impinged, 635, 637, 641 trace metals, 693, 699 parasites and disease, 462 Cobalt weight-length relation, 456-457 analysis, 698 Dufford, Donald W., 559 concentrations Eddy diffusion (see Phytoplankton) airborne particulates, 704, 724 Electrical production, 286 coal, 703 Entrainment. fish (see also Impingement) Corbicula fluminea, 713 effects, 652-653 fly ash, 700-702 eggs, monthly, 647 sediment, 710, 728 gizzard shad larvae, 620 distribution in soils, 706 larvae, numbers Coelotanypus concinnus, 363, 369, 370. 371 diurnal, 649 Commonwealth Edison Company, iv-vi estimated, 651 Condition factor, fish monthly. 648 bluegill. largemouth bass, yellow bass, 455-460 methods, 644-647 largemouth bass, first year. 522, 524, 527-528 Fish (see also Growth, Food habits. Larval fishes. methods, 449-450 Movements) Copper biomass (see Fish, relative abundance, standing analysis, 698 crop) Aug. 1981 Index 733 distribution {see also Water temperature, tag retrieval, 537-541 Radiotelemetry) white bass, 537-544, 548, 554 seasons, 425-430 Fishes. larval (see Larval fishes) temperature, 427-430 Fishing (see also Creel census) parasitism and disease, 460-463 age of fishermen, 599, 601 populations composition. 417-418 distance traveled, 601 population dynamics, 413 597, effort, 597, 599, 605-614 population estimates methods, 598, 607-608, 610 carp, 538, 545-546 seasonal, 597-602, 607-613 largemouth bass, 538, 544-545 species sought relative abundance bluegill, 599-604, 613-614 months, 420 609, 611, carp, 599-604, 606, 610-611 numbers, 417 channel catfish, 599-604. 606-607 stations, 423 largemouth bass. 599-606 weights, 417-423 white bass, 599-604, 606, 608-609 years, 418-419 white crappie, 599-604, 609, 611-612 reproduction carp, 439-440, 445-448 Fly ash, 693, 698, 699 largemouth bass, 439-444 Food habits, fishes white bass, 439, 444 bluegill spawning time amount, 513, 515 carp, 439 competition, 512, 516 largemouth bass, 439, 441 empty stomachs, 517 white bass, 439, 444 insects as food, 513-514 standing crop intake vs. discharge arms, 513-517 control arm, 437 plants as food, 513-514 cove rotenone samples, 436-438 seasons, 514-517 discharge arm, 436-437 size offish, 513, 515-516 fish kills, effects, 467 zooplankton as food, 513-514 intake arm, 436-437 channel catfish mark-andrecapture estimates crayfish as food, 506 carp, 545-546 fish as food, 505-507 largemouth bass, 544-545 insects as food, 505-507 methods of measuring, 433-435 intake vs. discharge arms, 506 total dissolved solids, effects, 439 plants as food, 505-507 tag retention (see also Fish tagging) seasons, 506-507 carp, 543-544 size of fish, 506 largemouth bass, 542-544 freshwater drum white bass, 543-544 amount, 508 trace metals insects as food, 508 analysis. 699, 715 intake vs. discharge arms, 508 concentrations, 440, 691 seasons, 609 samples, 696 size of fish, 509 Fish kills largemouth bass {see also Bass, largemouth) cause, 466-467 amount, 504 extent, 464-467 crayfish as food, 504-505 occurrence. 464-466 fish as food, 503-505 Fish tagging (see also Fish) insects as food, 503-504 anchor tags, 536 intake vs. discharge arms, 504-505 carp, 537-555 Lepomis as food, 503 information retrieval, 539-542 seasons, 504 largemouth bass, 537-556 shad as food, 502-503 methods, 537-539 size of fish, 503-505 objectives of tagging, 536-537 thermal effects, 503-504 population estimates zooplankton as food. 504-505 carp, 545-546 largemouth bass, first year largemouth bass, 544-545 empty stomachs, 530-531 radio transmitters, 559 food items, 529-532 recaptures, 541-542 intake vs. discharge arms, 529-534 standing crop estimates seasonal, 530-531 carp, 546 size of fish. 532-534 largemouth bass, 545 methods of study. 502. 521-522 survival effects, 542 objectives of study. 500. 528 tag retention, 542-544 species studied. 500-501. 528 734 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 yellow bass size, 642 amount, 510-511 temperature effects, 642-644 insects as food, 510 velocity at intake. 642 plants as food, 510 Kincaid Generating Station {see Generating sta- seasons, 512 tion) size of fish, 511 Kocher, Richard, 413, 536, 559 zooplankton as food, 510 Lake Sangchris Generating station basin. 285-286 intake structure, 632-633 lake. 286-288 location and development, 283 project, 279-289 {see also iv-vi) operation, 281 project inquiries. 281-283 maturity. 440-441 Gonad Larimore, R. Weldon, vi, 279. 559 Gonosomatic index, 440-443 Larval fishes Growth, Corbicula, 381-382, 384-385, 387-388 bluegill {see Lepomis larvae) Growth, fishes {see also Fish tagging) distribution annual, of tagged fish, 552 coves, 617 bluegill, 452 depth, 617, 620. 623. 626, 627 carp, 451 discharge arm. 617-620, 624, 627-629 analysis, 552-553 intake arm, 617-620, 624-625, 626. 627-629 552-555 intake vs. discharge arms, seasonal, 617-619, 624-625, 627-629 loss of length-weight, 555 size relations, 617, 621, 623, 626-627 rate, 553-555 temperature effects, 617, 622-623, 627 channel catfish, 454-455 temporal, 617, 620-621 gizzard shad, 452 tributary mouths, 617 bass. 453-454 largemouth wind effects, 627 analysis, 552-553 DoTOsoma cepedianum {see gizzard shad) annulus formation, 538, 555-556 entrainment, 620 vs. discharge arms, 552-556 intake 538, gizzard shad. 617-621. 623, 626 loss of length-weight, 555 green sunfish {see Lepomis larvae) 553-555 rate, Lepomis larvae, 624-627, 648-654 effects, 555-556 thermal MoTone larvae, 627-629 bass, first year largemouth study in Lake Sangchris actual growth, 523-526 methods, 615-617 527-528 condition of fish. 522. 524. objectives, 615 intake vs. discharge arms, 522-528 white bass {see Morone larvae) methods of study, 521-522 yellow bass (see Morone larvae) seasonal. 525 Lead thermal effects. 522, 527 analysis. 698 tag effects, 542 concentrations tagged carp, 552-555 airborne particulates, 726 tagged largemouth bass. 552-555 coal, 700, 703 tagged white bass, 552-555 Corbicula fluminea, 713 yellow bass, 452 fly ash, 700-702 white bass, 453 sediment, 710, 729 analysis, 552-553 distribution in soils, 707, 709 intake vs. discharge arms, 552-554 Legal issues, iv-v rate, 553-554 Lepomis (see also Bluegill; Halffield, Donald R, Jr., 500 Sunfish. green) Heat exchange, 279-281 distribution, 624-627 Hexagenia entrained, 648-654 {see also Entrainment) food of channel catfish, 506 Lepomis cyanellus (see Sunfish. green) food of freshwater drum, 507 Lepomis macrochirus (see Bluegill) food of largemouth bass, 529 Light attenuation (see Phytoplankton) Ictalurus melas {see Bullhead, black) Lotus, American water (see Nelumbo lutea) IctaluTus punctatus (see Catfish, channel) McGraw Wildlife Foundation, 661 Impingement, fish {see also Entrainment) McNumey, John M., 413. 500. 536, 559, 585. 594 condition of fish, 644 Mercury effects, 653-654 analysis. 698 estimated numbers, weight, 640-641 concentrations kinds taken, 635 airborne particulates, 704 methods, 634 carp muscle, 440 numbers, weights by month, 635-637 carp ovaries, 440. 446-447 numbers per water volume, 638 coal. 703 seasonal, 639 fishes. 716-717 Aug. 1981 Index 735 fly ash, 700-702 periodicity, 324 sediment, 710, 713, 729 photosynthetic rates, 322, 338 Micropterus salmoides (see Bass, largemouth) sampling, 320 Monzingo, Richard G., iv-vi spatial distribution, 330, 333 MoTone {see also Bass, white; Bass, yellow) species diversity, 323, 331 entrained {see also Entrainment), 648-654 species evenness. 323, 331 larvae distribution, 627-629 water temperature, 335 MoTone chrysops {see Bass, white) Pondweed, American {see Potamogeton nodosus) Movements, fishes {see also Bass, largemouth; Fish Population estimates, fishes {see Fish tagging) tagging; Radiotelemetry) Porak, Wesley, 631 carp, tagged Potamogeton nodosus (see also Aquatic distance, 549-652 macrophytes) intake vs. discharge arms, 546-550, 553 tissue analysis, 396-407 sex. 549 trace metals, 696, 699, 713 size of fish, 549-550 waterfowl food, 681 thermal effects, 547-548 Precipitation, 287 {see also Water quality) thermal zones, 550 Primary productivity {see Phytoplankton, time, 550 photosynthetic rates) largemouth bass, tagged Procladius bellus, 363, 369, 370, 371 distance, 549-552 Radiotelemetry, largemouth bass {see also Radio intake vs. discharge arms, 538, 546-550, 553 transmitters; Bass, largemouth) sex, 549 caught by fishermen, 557-578, 583 size of fish, 550 Lake Sangchris. 560 thermal effects, 538, 547-548 Lake Shelbyville, 560 tagged fish Radio transmitters {see also Bass, largemouth) anchor-tagged largemouth bass, 546-548, description, 559 549-551 implantation effects, 583 anchor-tagged white bass, 546-548, 549-550, Reproduction 551 carp, 439-440 thermal zones, 546-548, 549, 550, 551 channel catfish, 425, 432 radio transmitters in largemouth bass, largemouth bass, 439, 441 562-583 white bass, 439 white bass, tagged zooplankton, 342, 347, 350, 356 distance, 549-552 Rotenone surveys {see Fish, standing crop) intake vs. discharge arms. 548-550, 553 Sanderson, Glen C., 656 size of fish, 550 Seasonal abundance spawning, 548 benthic macroinvertebrates, 366 Naiad, brittle, waterfowl food, 680 phytoplankton. 324 Najas minor {see Naiad, brittle) Sedimentation rates, 710 Nelumbo lutea, 396-401, 681 Sediment, lake Nickel analysis of trace metals, 710 analysis, 698 concentrations concentrations cadmium, 727 airborne particulates, 704, 725 chromium, 727 American pondweed. 71S cobalt. 728 coal, 703 Copper. 728 Corbicula Jluminea, 713 lead, 729 fly ash, 700-702 mercury, 729 sfdiment, 710, 730 nickel. 730 distribution in soils, 708 zinc, 730 Nitrogen, from waterfowl. 685 samples, 695 Nutrient loading, by waterfowl, 685 Selenium Oxygen content {see Water quality) analysis, 698 Parasitism {see Fish, parasitism and disease) fly ash, 700-702 Particulate sampling, airborne, 723 concentrations in Particulates, airborne, 693. 698. 703. 723-726 Shad, gizzard {see also Larval fishes) Periodicity {see Phytoplankton, Zooplankton) condition factor, 457-458. 460 Pesticide residues, carp tissues. 440-441. 447-448 entrained, 648-654 Phosphorus, waterfowl deposited, 685 food of largemouth bass, 502, 529-531 Phytoplankton growth, 452 biovolume, 322, 325 impinged, 635-636, 639-640, 643, 644 eddy diffusion, 322-353 seasonal distribution, 427-430 identification, 321 weight-length relation, 456-457 light attenuation, 322-323 Shiner, golden, 635, 637, 641 736 Illinois Natural History Survey Bulletin Vol. 32, Art. 4 Slag nitrogen, 300-305 analysis. 698 phosphorus, 298. 304-305 duck ingested, 682 relationships among variables. 312 samples, 693 water temperature, 313-317 trace metals, 691, 714 Water temperature (see also Aquatic Smith, Kenneth E.. 691 macrophytes; Growth, fishes: Bass. Smith, Valerie, 585 largemouth; Larval fishes; Phytopiankton; Soil Water quality) analysis, 698 annulus formation by largemouth bass. 538. sampling sites, 695 555 trace metals, 691 benthic macroinvertebrate distribution, 362 Standing crop (see Fish. Fish tagging, fish catch, 430 Zooplankton) fish kills, 465 Stress, heat caused, 280-281 fish movements. 546-556 Sule, Michael J., 500, 520 growth of largemouth bass. 419 Sulfur, concentrations high, refuge from. 589 airborne particulates, 704 monthly preferred of largemouth bass. 569-570 coal, 703 movements of largemouth bass. 562-567 ny ash, 700-702 parasitism and disease, 460-463 soils, 708 preferred Sunfish, green carp. 588-592 entrained (see Lepomis) largemouth bass. 562. 570-571, 573. 588-592 impinged, 635-636, 640 reproduction of largemouth bass. 419 trace metals, 715-716 upper lethal, 591 Temperature, air, 287 (see also Water waterfowl distribution, 659, 661, 668 temperature) Waterfowl Thermal effects (see Fish tagging, Movements, body weights, 678 Stress, Water temperature) census, 659 Thermoregulation collisions with power lines, 678 carp, 585-592 food habits, 680 electric shock, effects on, 586-587 hunting, 659 largemouth bass, 585-592 nutrient loading, 660 Trace elements organ weights, 684 analysis, 709 populations, 663 concentrations population composition, 663 airborne particulates, 704 temperature on distribution, 668 coal, 700, 703 Webb, Donald W.. 358 Corbicula fluminea, 713-714 Weight-length relation, fishes. 449-450. 455-457 fishes, 718 Zinc fly ash, 702 analysis. 698 Lake Sangchris, 719 concentrations Potamogeton nodosus, 713 airborne particulates, 704, 726 sediment, 710-712 American pondweed. 713 slag, 701 coal, 703 physical characteristics of fishes analyzed, 715 Corbicula fluminea, 713 TranquilH, John A., vi, 279, 378, 413, 536, 559, fly ash. 700-702 631 sediment. 710. 730 Vanadium distribution in soils, 709 analysis, 698 Zooplankton (see also Food habits, fishes) concentrations common forms coal, 703 Bosmina longirostris, 347, 349 Corbicula fluminea, 713 Brachionidae, 347. 349 fly ash, 700-702 Ceriodaphnia quadrangula, 349 sediments. 710 Cyclops vemalis, 350 Vegetation (see Aquatic macrophytes) Daphnia parvula. 347 Waite, Stephen W., 342 Diaptomus siciloides, 347 Water quality Filinia longiseta, 349 analytical methods, 291-296 Hexarthra, 349 benthos distribution, 362 Ilyocryptus sordidus, 349 climatological differences, 298-300 Kerat'ella, 349 dissolved oxygen, 296, 298, 305-306 Kurzia, 346 fish kills. 465-467 Macrocyclops albidus. 347. 350 homogeneity in water column. 296, 298 Mesocyclops edax, 350 lake flow pattern. 290 Moina, 346 1 Aug. 1981 Index 737 Simocephalus, 346 species diversity, 352 Synchaeta, 349 limnetic communities, 343 composition of communities occurrence absence of Leptodora kindtii, 342. 346, 356 chemical limitations, 342, 347, 355 limnetic communities. 343 in cooling loop. 342 seasonal variation, 356 number of species, 342 species, abundance, 344, 350, 351 periodicity entrainment, 342, 353, 355 dicyclic, 342, 347, 356 food of bluegill, 513-515 monocyclic, 342, 347 food of largemouth bass, 504-505. 529-534 seasonal, 350 food of yellow bass, 510-51 physicochemical effects heated discharge, effects on transcursion, 347 additional species, 356 traumatization, 353 damping phenomenon, 352 reproduction. 342, 347, 350, 356 numbers, 342-343 species diversity, 351-356 periodicity, 347 standing crop (biomass). 342. 353, 355-356 . Some Publications of the ILLINOIS NATURAL HISTORY SURVEY BULLETIN lis.— The Life Histories o{ Elheostoma oUvace and Etheoitoma striatulum. Two Species Volume 31, Article 10. — The Bantam Sunfish, ' Darters in Central Tennessee. By Lawrence Lepomis lymmetrictis: Systematics and Distribu- Page. August 1980. 14 p. tion, and Life History in Wolf Lake, Illinois. By Brooks M. Burr. Steptember 1977. 30 p.. index. 114. — Identification and Descriptions of the UW mate Instar Larvae of Hydraecia immanis (Ho Volume 32, Article 1 . -Waterfowl Populations and Vine Borer) and (Potato Stem Borer) the Changing Environment of the Illinois River H. micacea (Lepidoptera: Noctuidae). By George L. God- Valley. By Frank C Bellrose, Fred L. Paveglio, frey. February 1981. 8 p. Jr., and Donald W. Steffeck. August 1979. 54 p.. index 115 —Illinois Pheasants: Population, Ecology. Dis- Volume 32, Article 2. — Primary Insect Types in the tribution, and Abundance, 1900-1978. By Illinois Natural History Survey Collection, Ex- Richard E. Warner. August 1981. 24 p. clusive of the Coljembola and Thysanoptera. By Donald W, Webb. July 1980. 138 p., index. 116. — Effects of Ingested Lead-Iron Shot on Mallards. By Glen C. Sanderson. Horace VV., Volume 32, Article 3. — The Genera of Nearctic Norton, and Sarah S. Hurley. August 1981 . 16 pJ Therevidae. By Michael E. Irwin and Leif Lyneborg. November 1980. 85 index. p., 117. — The Life History of the Tennessee Snubno Darter, Etheostoma simoterum, in Brush Creek,l Tennessee. By Lawrence M. Page and Richard \.S BIOLOGICAL NOTES Mayden. August 1981. 12 p. 108. — The Nest Biology of the Bees Andrena (Melandrena) regutaris Malloch and Andrena CIRCULAR (Melandrena) carlini Cockerell (Hymenoptera: Andrenidae). By Martha Northam Schrader and 49 —The Dunesland Heritage of Illinois. B]j Wallace E. LaBerge. August 1978. 24 p. Herbert H. Ross. August 1963 (Reprinted Ma| 1974). 28 p. 109— Illinois Birds: Ciconiiformes. By Jean W. Graber. Richard R. Graber, and Ethelyn L. 51.— Illinois Trees: Selection, Planting, and Carel Kirk. August 1978. 80 p. By J. Cedric Carter. March 1977 (Third printing). 123 p. 110 —Illinois Birds: Sylviidae. By Jean W. Graber, Richard R, Graber, and Ethelyn L. Kirk. July 52 —Fertilizing and Watering Trees. By Dan 1979. 22 p. Neely and E. B. Himelick. December 1971 (Third printing). 20 111. — Monitoring the Seasonal Appearance and p. Density of the Black Cutworm with a Virgin 54.— Corn Rootworm Management in Canning Female Trap. By Lynn Pautler, William G. Sweet Com. By W. H. Luckmann. T. Shaw. D.l Ruesink, Hans E. Hummel, and William H. J. E. Kuhlman. R. Randell, and C. D. LeSar.f Luckmann. July 1979. 7 p. March 1975. 10 p. 112.— The Life History of the Least Darter. Etheostoma microperca, in the Iroquois River, Il- 55. — Observing. Photographing, and Collecting! linois. By Brooks M. Burr and Lawrence M. Plants. Bv Kenneth R. Robertson. .August 1980. Page. August 1979. 16 p. 62 p. List of available publications mailed on request No charge is made for publications of the IixiNOis Natural History Survey. A single copy of most] publications will be sent free to anyone requesting it until the supply becomes low. Costly publications, morel than one copy of a publication, and publications in short supply are subjects for special correspondence. Such correspondence should identify the writer and explain the use to be made of the publication orl publications. Address orders and correspondence to the Chief, Illinois Natural History Survey Natural Resources Building 607 £. Peabody, Champaign, Illinois 61820 ^ ^ ^ ^ ^