DETERMINATION OF THE RELATIVE STATE OF EUTROPHY OF NAVIGATION POOL NO. 7 OF THE UPPER MISSISSIPPI RIVER BY MEANS OF AN ALGAL ASSAY PROCEDURE A Thesis Submitted to the Faculty of University of lrJisconsin La Crosse by Stephen M~ Clark In Partial Fulfillment of the Requirements for the Degree of Master of Science July 1974 '4- ) ,. "V UNIVERSITY OF WISCONSIN La Crosse, Wisconsin 54601 COLLEGE OF ARTS, LETTERS, AND SCIENCES Candidate: Stephen M. Clark We recommend acceptance of this thesis to the College of Arts, Letters, and Sciences in partial fulfillment of this candidate•s requirements for the degree Master of Science in Biology . The candidate has completed his oral defense of the thesis. 107/1 I I I '-1 This thesis is approved for the College of Arts, Letters, and Sciences ii ABSTRACT This study was undertaken to refine a method to determine the eutrophic state of water by the application of a static bioassay pro­ cedure with algae as the test organism. The procedure was applied to Navigation Pool No. 7 in the Upper Mississippi River (Dresbach, Minnesota) to determine the effect of this navigation pool on nutrient dynamics of the river. Water samples were collected from four sampling sites twice per month from March 12 to October 1, 1972. The pH, temperature, nitrate - 1 ) - 3 ) (N0 3 and phosphate (Po 4 were determined for each sample. Filtered water samples were inoculated with a predetermined quantity of Scenedesmus quadricauda and Chlorella vulgaris and a known amount of 14 • NaHC 03 Samples were incubated for 2 hours under controlled environ­ mental conditions. Incorporation of C14 during photosynthesis provided a direct approach to the measurement of primary productivity. Productivity values (mgC/1) and nitrate - 1 ) and phosphate (No 3 - 3 ) (Po 4 levels were at a maximum in March and a minimum in May, June and August. Due to nutrient levels in excess of those required for maximum productivity, no significant correlations were detected between productivity values and the nitrate and phosphate levels observed. The upstream sampling site demonstrated significantly higher (0.1) produc­ tivity values, nitrate levels and phosphate levels than downstream iii sampling sites. Navigation Pool No. 7 appeared to be an effective nutrient trap. Incoming nutrients were assimilated into the abundant plant growth and subsequently trapped within the sediments. Decay of this vegetation appeared to be responsible, in part, for cyclic nutrient phenomena within the pool. iv TABLE OF CONTENTS page LIST OF TABLES . v LIST OF FIGURES. Vi INTRODUCTION . :. 1 METHODS AND r~ATERIALS. 7 Sampling ..... 7 Chemical measurements 8 Production of inocula 9 Preparation of inocula. 9 Preparation of test flasks. 10 Preparation of the sample for counting. 10 RESULTS AND DISCUSSION . 12 Results and discussion. 12 Conclusions ...... 19 SELECTED REFERENCES. 21 APPENDIX . .. 24 v LIST OF TABLES / Table Page 1. Primary productivity (mgC/1 /hr), nitrate (NO 3 1), and phosphate (P04-3) levels in Navigation Pool No. 7, recorded at Site I, Lock and Dam No. 7, Dresbach, Minnesota, 1972 ................. 24 - 1 2. Primary productivity (mgC/1/hr), nitrate (NO 3 ), and phosphate (PO; 3) levels in Navigation Pool No. 7, recorded at Site II, on French Island, La Crosse, Wisconsin, 1972 ..........•........ 25 3. Primary productivity (mgC/1/hr), nitrate (NOt 1), and phosphate (P04 .. 3) levels in Navigation Pool No. 7, recorded at Site III, the Onalaska Spillway, Onalaska, Wisconsin, 1972. 26 4. Primary productivity (mgC/1/hr), nitrate (N0 3-1), and phosphate (P0 4-3) levels in Navigation Pool No. 7, recorded at Site IV, the Brice Prairie Boat Landing, Brice Prairie, Wisconsin, 1972. 27 5. Correlation coefficients (r) bet\'Jeen productivity . of test species and nitrate (No3-1) 1eve 1s in Navigation Pool No. 7, 1972. 28 6. Correlation coefficients (r) between productivity of test species and phosphate (P0 -3) levels in 4 Navigation Pool No. 7, 1972. 28 . 7. Test of significance between productivity values of selected pairs of sample sites in Navigation Pool No. 7, 1972. ......•..... 29 8. Test of significance between nitrate (N03- 1 ) values observed at Brice Prairie Public Boat Landing and several sites in Navigation Pool No. 7, 1972. 30 9. Test of significance between phosphate (P04- 3) values observed at Brice Prairie Public Boat Landing and several sites in Navigation Pool No. 7, 1972. 30 vi LIST OF FIGURES / Figure Page 1. Location of sampling sites in Navigation Pool No.7, 1972 .............. 31 2. Primary productivity (mgC/1/hr) for Scenedesmus guadricauda and Chlorella vulgaris at Site I in Navigation Pool No. 7 at Lock and Dam No. 7, Dresbach, Minnesota, 1972 ........... 32 3. Primary productivity (mgC/1/hr) for Scenedesmus guadricauda and Chlorella vulgaris at Site II in Navigation Pool No. 7 at French Island, La Crosse, Wisconsin, 1972. ..... 33 4. Primary productivity (mgC/1/hr) for Scenedesmus guadricauda and Chlorella vulgaris at Site III in Navigation Pool No. 7 at the Onalaska Spillway, Onalaska, Wisconsin, 1972 ........... 34 5. Primary productivity {mgC/1/hr) for Scenedesmus guadricauda and Chlorella vulgaris at Site IV in Navigation Pool No. 7 at the Public Boat Landing, Brice Prairie, Wisconsin, 1972. ..... 35 1 6. Nitrate (No 3 - ) and phosphate (Po 4 -3) levels (mg/1) at Site I in Navigation Pool No. 7 at Lock and Dam "No. 7, Dresbach, Minnesota, 1972. .... 36 - 1 ) - 3 ) 7. Nitrate (No 3 and phosphate (Po 4 levels (mg/l) at Site II in ~avigation Pool No. 7 at French Island, La Crosse, Wisconsin, 1972. ..... · · . · . · 37 8. Nitrate (No - 1 ) and phosphate (Po -3) levels (mg/1) 3 4 at Site III in Navigation Pool No. 7 at the Onalaska Spillway, Onalaska, Wisconsin, 1972 ........ 38 1 3 9. Nitrate (N0 3- ) and phosphate (P0 4 - ) levels (mg/1) at Site IV in Navigation Pool No. 7 at the Public Boat Landing, Brice Prairie, Wisconsin, 1972. 39 INTRODUCTION In the past few decades, human cultural activities have accelerated the natural rate of eutrophication and lead to disturbances of freshwater ecosystems. The term 'eutrophication' adopted by the Eutrophication Group of the Organization for Economic Cooperation and Development is defined as: 11 the nutrient enrichment of waters, which frequently results in an array of symptomatic changes, among which increased production of algae and other aquatic plants, deterioration of fisheries, deteriora­ tion of water quality, and other responses are found objectionable and impair water-use 11 (Bartsch, 1970). Eutrophication due to mans' activities is as old as history and regardless of the point on the time­ scale that human influence is added, the end result is the same: the aquatic environment moves more rapidly to advanced stages of eutrophica­ tion (Hasler, 1947). Only recently have people noticed and demanded workable solutions to the problem of accelerated eutrophication. One approach to this problem is to study the effects of eutrophication on the primary producer organisms present in a given body of water. The rate of carbon fixation at the primary producer level provides an assessment of the interaction of physical, chemical, and biological factors which determine the actual fertility of any environment (Goldman, 1961). The level of fertility and the rate of primary production are of fundamental importance for the understanding and comparing lakes as biological units (Goldman, 1960). -1- -2- Productivity is a major factor to consider in classifying lakes since changes or differences in basic productivity influence the rate of accumulation of organic matter in successive trophic levels~ Ryther (1956) stated that the productivity of natural waters is judged on the quantity of organic matter which they support at a given moment, but he emphasized that production must be considered as a rate. MacFayden (1948) defined productivity as equal to the rate of flow of matter. Lindeman (1942), in proposing the trophic-dynamic view of ecology, re~ognized the importance of rate measures and the need to develop means of better quantifying rate functions. The interest in energy transformations helped to establish rates as being a more meaningful measurement than standing crop (Goldman, 1961). In examining an ecosystem, one is primarily concerned with the real production of organic matter that is added to the environment, or net photosynthesis. Primary productivity is thus taken to be the net rate of fixation of organic carbon in photosynthesis (Goldman, 1960). There are dangers inhe~ent in predicting productivity with chemical measurements alone.· The mere presence of chemicals does not prove their biological availability (Hutchinson, 1944; Potash, 1956). There is - considerable variation in nutrient levels from week to week. Qualitative effects of phytoplankton periodicity are most likely due to these fluctua­ tions in nutrient levels. Clear-cut correlations between chemical conditions and productivity are not to be expected. Among the several factors one must consider in any productivity study are (1) inorganic nutrients other than nitrogen and phosphorus, (2) presence of organic substances in the water, (3) the physiological conditions of the organisms tested and (4) competitive relationships between test organisms -3- (Hutchinson, 1944). Productivity is most frequently defined on a chemical basis by examining nitrogen and phosphorus levels. Hasler (1947), Verduin (1956), Hutchinson (1957) and Potash (1956) all stated that nutrients other than nitrogen and phosphorus are normally present in excess. Although nitrogen and phosphorus are often found to be limiting in natural environments, their presence is not necessarily directly proportional to the general state of eutrophy. One must consider the levels of all requirements for plant growth. 1his implies that a biological assay method be employed along with chemical measure­ ments to determine the relative state of eutrophy of a given body of water. The use of an algal assay procedure for examination of the eutrophic state of a body of water has the following advantages: {1) the inclusion of all dissolved substances in the assay procedure, and (2) comparability of data from several sites in the same environmental system.