AME 32:275-285 (2003)  -  doi:10.3354/ame032275

Effect of phosphorus amendments on present day plankton communities in pelagic Lake Erie

Steven W. Wilhelm1,2,*, Jennifer M. DeBruyn2,3, Osnat Gillor4,9, Michael R. Twiss5,10, Kasey Livingston6, Richard A. Bourbonniere6, Lisa D. Pickell7, Charles G. Trick7, Amanda L. Dean1, R. Michael L. McKay8

1Department of Microbiology, University of Tennessee, 1414 West Cumberland, Knoxville, Tennessee 37996, USA
2Center for Environmental Biotechnology, University of Tennessee, 676 Dabney Hall, Knoxville, Tennessee 37996, USA
3Department of Biology, Queen¹s University, Kingston, Ontario K7L 3N6, Canada
4Division of Environmental Sciences, Graduate School of Applied Science and Technology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
5Department of Chemistry, Biology and Chemical Engineering, Ryerson Polytechnic University, Toronto, Ontario M5B 2K3, Canada
6National Water Research Institute, Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario L7R 4A6, Canada
7Department of Biology, Biological and Geological Sciences Building, University of Western Ontario, London, Ontario N6A 5B7, Canada
8Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA
9Present address: Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8106, USA
10Present address: Department of Biology, Clarkson University, Potsdam, New York 13699-5805, USA

ABSTRACT: To address questions regarding the potential impact of elevated total phosphorus (TP) inputs (due to relaxed regulations of TP loading), a series of TP enrichment experiments were conducted at pelagic stations in the 3 hydrologically distinct basins of Lake Erie. Results of nutrient assimilation measurements and assays for nutrient bioavailability suggest that the chemical speciation, and not concentration, of nitrogenous compounds may influence phytoplankton community structure; this in turn may lead to the selective proliferation of cyanobacteria in the eastern basin of the lake. Assays with cyanobacterial bioluminescent reporter systems for P and N availability as well as Ntot:Ptot assimilation ratios from on-deck incubation experiments support this work. Considered in the context of a microbial food web relative to a grazing food web, the results imply that alterations in current TP loading controls may lead to alterations in the phytoplankton community structure in the different basins of the Lake Erie system.

KEY WORDS: Nutrient loading · Lake Erie · Microbial process · Bioluminescent reporters

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