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Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. VI. plankton dynamics, 1971-1973, VII. phytoplankton 1971-1973, VIII. zooplankton, 1971-1973, IX. diel plankton, 1973-1974, X. benthic algae species list Item Type monograph Authors Walker, Linda M.; Steidinger, Karen A.; Tester, Lana A.; Glass, Brian M.; Roberts, Beverly S.; Moffler, Mark D.; Van Breedveld, Jacques F. Publisher Florida Department of Natural Resources, Marine Research Laboratory Download date 08/10/2021 23:23:22 Link to Item http://hdl.handle.net/1834/18775 Nearshore Marine Ecology at Hutchinson Island, Florida: 1971-1974 VI. Plankton Dynamics, 1971-1973 LINDAM. WALKERAND KAREN A. STEIDINGER VII. Phytoplankton, 1971-1973 LANAA. TESTERAND KAREN A. STEIDINGER VIII* Zooplankton, 1971-1973 LINDAM. WALKER,BRIAN M. GLASS, ANDBEVERLY S. ROBERTS IX. Die1 Plankton, 1973-1974 LINDA M. WALKER X. Benthic Algae Species List MARKD. MOFFLER ANDJACQUES F. VAN BREEDVELD Florida Department of Natural Resources Marine Research Laboratory Number 34 August 1979 Florida Department of Natural Resources Bob Graham Governor George Firestone Bill Gunter Secretary of State Treasurer Jim Smith Doyle Conner Attorney General Commissioner of Agriculture Gerald A. Lewis Ralph D. Turlington Comptroller Commissioner of Education Joseph W. Landers, Jr. Interim Executive Director The Florida Department of Natural Resources Marine Research Laboratory publishes two series, Memoirs of the Hourglass Cruises and Florida Marine Research Publications. The latter, published at irregular intervals and numbered consecutively, supersedes the following Marine Research Laboratory publications: Professional Papers Series Technical Series Special Scientific Reports Educational Series Leaflet Series Salt Water Fisheries Leaflet Series The Publications include articles, monographs, bibliographies, synopses, and educational summaries dealing with the marine resources of Florida and nearby areas. Copies are distributed to libraries, laboratories, and research institutions throughout the world. Communications concerning receipt or exchange of publications should be directed to the Librarian of the Marine Research Laboratory. Charles R. Futch Editor FLORIDA MARINE RESEARCH PUBLICATIONS Number 34 Nearshore Marine Ecology at Hutchinson Island, Florida: 1971-1974 VI. Plankton Dynamics, 1971-1973 LINDAM. WALKER ANDKAIZElN A. STEIDINGER VII. Phytoplankton, 1971-1973 LANAA. TESTERAND KAREN A. STEIIIINGER VIII. Zooplankton, 1971-1973 LINDAM. WALKER,BRIAN M. GLASS,AND BEVERLY S. ROBERTS IX. Die1 Plankton, 1973-1974 LINDA M. WALKER X. Benthic Algae Species List MARKD. MOFFLERAND JACQUKS F. VAN BREEDVELD Florida Department of Natural Resources Marine Research Laboratory 100 Eighth Avenue SE St. Petersburg, Florida 33701 VI. Plankton Dynamics, 1971-1973 ABSTRACT Walker, L. M. and K. A. Steidinger. 1979. Nearshore Marine Ecology at Hutchinson Island, Florida: 1971-1974. VI. Plankton Dynarr6cs, 1971-1973. Fla. Mar. Res. Publ. No. 34. PP. 1-l5.Two years of phytoplankton, zooplankton and physicochemical data for the western Atlantic off Hutchinson Island, Florida, indicate the dynamic composition of these nearshore waters. Oceanic influences, as judged by plankton composition and abundance, were most obvious in winter and summer. Estuarine influences from the Indian River system were correlated with time of collection and tidal cycles. The estuarine discharge and associated higher inorganic nutrient (e.g. SiOz-Si means of 6.77 to 8.90 pg-atomslliter) and higher suspended particulate loads appeared to substantially affect stations closest to the inlet. The shoal station (111) which was furthest from shore was the least influenced, Combined inorganic nitrogen values (means of 1.40 to 2.87 ~g-atomslliter)and high orthophosphate values (means of 3.16 to 6.79 pg-atoms/liter) accounted for low N:P ratios of between 1 and 2. Surface chlorophyll a minus phaeopigment values (means of 1.02 to 2.34 mg/m3) and primary production estimates (means of 0.26 to 0.46 g Clm2/day) suggest that this fluctuating environment is moderately productive. Plankton species composition reflected strong Caribbean and North Equatorial affinities with many of the species being tropical-subtropical or cosmopolitan. Pelagic plankton in relation to tidal cycles and current structure demonstrates the transient nature of these organisms. The presence and diversity of benthic diatoms in oblique net hauls and high chlorophyll a in bottom waters (1.47 to 2.86 mg/m3 station means) implies that a resident or transient phytomicrobenthic flora may be more significant to higher trophlc levels in the sampling area than pelagic phytoplankton. These data are presented as part of a "base-line" study to characterize the nearshore waters off Hutchinson Island prior to the operation of the Florida Power and Light Company's St. Lucie Power Plant Unit #1. This public document was promulgated at an annual cost of $7541 or $3.77 per copy and partially funded by the Florida Power and Light Company to preserve, manage, and protect Florida's marine resources and increase public awareness of the detailed information needed to wisely govern our marine environment. INTRODUCTION AND RATIONALE METHODS AND MATERIALS Plankton and hydrographic analyses off Hutchin- Single plankton tows (0.5 m opening, 202 pm son Island, Florida, were conducted at five permanent mesh, 5:l length) were taken in a wide circle over each stations (Figure 1) as an integral part of a "base-line" fixed station at a speed of about 1-2 kn. Bimonthly study designed to provide hydrographic, floristic and collections were taken from September 1971 through faunistic data for a nearshore environment im- August 1972; monthly collections were from September mediately adjacent to a proposed nuclear power unit 1972 through August 1973. The haul was stepoblique, (St. Lucie Unit #I). The structure of the entire study 5 min. near the bottom and 5 min. at the surface. A as well as the physical nature of the sampling area General Oceanics Flowmeter Model 2030 was attached determined the extent of parameters measured. Water slightly off center for filtered seawater volume chemistry, current structure, sediment type, pelagic estimates. The net was backwashed between tows to and benthic assemblages demonstrate the dynamic avoid clogging. Single hauls can introduce a reported composition of these nearshore waters. variation of 23 to 50% (UNESCO, 1968); however, the The purpose of the plankton study was to define circular path, large volume filtered, step-oblique tow the pelagic realm and influencing physicochemical and five stations in a small area were judged to be parameters. Chlorophyll a (minus phaeopigments) was representative for estimates and comparisons. used as a measurement of phytoplankton biomass or Plankton samples were preserved in buffered 5% standing stock. Net phytoplankton (202 pm mesh) was seawater-formalin. Laboratory analyses typically collected to delineate oceanic intrusion and possibly involved subsamples from 0.01 ml to 10 ml, depending provide indicator species data. A prerequisite for on the taxon being counted; at least 100 specimens of oceanic indicator species is that they be easily the dominant taxon(a) were counted in gridded or lined identifiable; larger diatoms and dinoflagellates caught petri dishes. Usually two random rows of 5 squares in net hauls meet this criterion. Filtration of large each were observed for the zooplankton, while whole volumes of water was required to catch these less aliquots were observed for the phytoplankton (see abundant oceanic phytoplankters. Photosynthetic Walker, et al., 1979 and Tester and Steidinger, 1979 for nannoplankton was accounted for in chlorophyll a details). Methods used for collection and analyses biomass estimates; however, quantitative species followed those recommended by UNESCO, 1968; composition or percent composition (nannoplankton Edmondson and Winberg, 1971; Schlieper, 1972; Slack versus net plankton) were not differentiated. Smaller et al., 1973. mesozooplankters and larger microzooplankters were Basic inorganic nutrient analyses (NO,-N, numerically quantified from the same metered net haul NO,-N, NH,:N, PO,-P, Si0,-Si) were contracted to for major group categories, copepod genera and the University of South Florida Marine Science selected species. These numerical standing stock Institute for determination by Autoanalyzer tech- estimates were used to compare Hutchinson Island niques (Environmental Protection Agency, 1971). data with other coastal areas and to assess possible Samples were immediately preserved with mercuric indicator taxa. Gross primary productivity estimates chloride, kept at ambient temperature, filtered back at provide data for comparison purposes on a regional the field laboratory (Jensen Beach, Florida) and then basis. Basic inorganic macronutrients (N, P, Si) were refrigerated for "cooler" transport to St. Petersburg determined to evaluate within sample correlations, to for analyses. Monthly nutrient analyses were initiated project seawater "fertility" and to characterize in February 1972. influencing water masses. Temperature and salinity Chlorophyll a was determined by the spectropho- data were recorded to express observed ranges for tometric methods outlined in UNESCO (1966) and each taxon and, therefore, indicate potential toler- Lorenzen (1967). Water samples were brought to the ances. Other parameters such as phaeopigrnents and field laboratory, filtered, ground, extracted with 90% carotenoid-chlorophyll