Plankton Trophic Dynamics in Chesapeake Bay: Top Down vs. Bottom Up Control of Copepod Populations
Our research is an important step towards understanding top-down and bottom-up processes of Chesapeake Bay. This research showed that predation by gelatinous zooplankton alone could not reduce copepod populations, and that the copepods generally appeared not to be food limited. Predation by sea nettle medusae probably could not have reduced ctenophore populations in the mid-Bay. Copepod production rates during the spring and summer were very high. Therefore, predation on grazers by gelatinous zooplankton probably does not affect the development of hypoxia in Chesapeake Bay, and probably does not significantly reduce foods needed by fishes. Our data provide critical information on the coupling of phytoplankton and zooplankton in the mesohaline portion of the Bay. This greater understanding of planktonic food web processes helps scientists and managers to understand the potential effects of toxic substances in Chesapeake Bay as well as reduced nutrient inputs.
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Jennifer Purcell and Michael R. Roman
Horn Point Laboratory
University of Maryland Center for Environmental Science
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