Effects of ribbed mussel grazing on the planktonic community of Long Island bays

J PAN; RM CERRATO; DJ LONSDALE

Providence, Rhode Island, USA

Congreso; 19th Biennial Conference of the Estuarine Research Federation; 2007

Estuarine Research Federation

This study implemented a mesocosm approach to study the potential effects of ribbed mussel (Geukensia demissa) grazing on different planktonic groups. Geukensia has the potential to feed on planktonic food sources of a broad range of sizes and plays a major role in shallow bays and marshes. 59-litre mesocosm tanks were assembled in situ, using ambient seawater from 3 Long Island (NY) embayments. Locations were chosen based on differences in chlorophyll a fractions (>20ìm, 5-20ìm and <5ìm). Experiments were run for short times (~2.5 h) and initial and final water samples were taken for different analyses. Clearance rates were estimated from: chlorophyll a contents for different size-fractioned components of the phytoplankton; microscopic analysis of the protistan microplanktonic community, and flow cytometry counts of the nano- and picoplanktonic communities. Morevoer, absorption efficiencies were calculated with the ash-free dry weight method. No obvious differences were found in clearance rates for different chlorophyll fractions. However, preliminary results suggest that for some micro- and nanoplankton groups (e.g. some toxic dinoflagellates) differences in clearance may cause beneficial shifts in the planktonic community.