Preliminary Investigations of Hard Clam Impacts on Food Web Interactions in the Plankton of Great South Bay. Poonam Maru, Syosset HS, Syosset, NY; Robert Cerrato and Darcy Lonsdale, Marine Sciences Research Center, Stony Brook University.
	Since the 1970's, there has been a dramatic decline in the abundance of hard clams in Long Island bays. This decline not only negatively affects the Long Island area economically, but potentially impacts the estuarine environment. In the near future, efforts may be underway to substantiallyincrease the density of hard clams in these bays. To evaluate the potential environmental impact of these efforts, weekly sampling of water in mesocosm experiments that manipulate clam density, and ambient water is being conducted to study how the presence or absence of clams may alter the food web not only by direct removal of phytoplankton but indirectly by negatively affecting some zooplankton grazers of phytoplankton. The size range of the most effective grazers that remove the greatest amount of phytoplankton biomass is being evaluated to better understand changes in food web interactions associated with the presence of clams. Preliminary results of our size-specific, predator-exclusion experiments suggest that the most effective grazers of the predominant size class of phytoplankton (< 5 um in diameter) are not significantly affected by the presence of clams. Future research will be done to better define which organisms are grazing on which prey and their effects on the planktonic ecosystem of Great South Bay. This work was supported by a training grant from New York Sea Grant (R-FBM-23).

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