Aquatic Sciences Meeting, Albuquerque 2001

PC12 Trophic Dynamic Studies

Date: Thursday, February 15, 2001

Location: Southwest Hall

Bundy, M, H, The Academy of Natural Sciences Estuarine Research Center, St. Leonard, USA, bundy@acnatsci.org

Riedel, G, F, The Academy of Natural Sciences Estuarine Research Center, St. Leonard, USA, friedel@acnatsci.org

Sanders, J, G, Old Dominion University, Norfolk, USA, jsanders@odu.edu

PHYTOPLANKTON MEDIATED IMPACTS OF TRACE METALS ON MESOZOOPLANKTON AND MICROZOOPLANKTON POPULATIONS

The seasonal effects of trace metals and enhanced nutrients on meso- and microzooplankton populations were investigated in a series of 6 mesocosm experiments conducted over a two and one half year period. 100-L tanks containing natural estuarine assemblages were exposed to elevated nutrients and to trace levels of Cd, As, and Cu alone, and in combination. Phytoplankton and zooplankton population responses to these stressors were followed over a 5-week period. The biomass of phytoplankton communities increased in response to nutrients and decreased in response to trace metal additions in all runs. The interactive effects of nutrient and trace metal additions varied with season. Microzooplankton were negatively impacted by trace metal additions and positively impacted by phytoplankton abundance in all runs. Mesozooplankton population response varied with phytoplankton species composition and biomass in the spring, and with phytoplankton biomass in the summer. There was a negative impact of biomass in spring, but only in tanks where large diatoms dominated the phytoplankton community. These results are discussed relative to potential seasonal differences in trace metal impacts on estuarine zooplankton and phytoplankton populations.

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Aquatic Sciences Meeting, Albuquerque 2001

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