Grazing selectivity of ribbed mussels (Geukensia demissa) to different noxious phytoplankton

J PAN; RM CERRATO; DJ LONSDALE

Atlanta, Georgia

Congreso; 2007 Benthic Ecology Meeting; 2007

The School of Biology at Georgia Tech

The ribbed mussel Geukensia demissa feeds on planktonic food sources of a broad range of sizes. The purpose of this work is to test whether ribbed mussel filtration is affected by the presence of the brown tide organism (Aureococcus anophagefferens) and the dinoflagelate Amphidinium carterae. Both of these species are harmful algae known to affect salt marsh and lagoonal systems.In order to study the ribbed mussel?s response to different proportions of noxious and nutritious phytoplankton and evaluate its selectivity of food items, we performed laboratory grazing experiments with individual ribbed mussels collected from a salt marsh on the north shore of Long Island (NY). These experiments had unialgal and mixed proportions of nutritious (Isochrysis galbana) and noxious phytoplankton. Experiments were performed with algae in their exponential growth phase from a modified batch culture. We estimated clearance rates from total chlorophyll content and absolute cell counts made using flow cytometry. Absorption efficiencies were also calculated. Preliminary experiments with blue mussels (Mytilus edulis) were used as an assay to establish the toxic effect of both A. carterae and A. anophagefferens on mytilids.Ribbed mussels were able to graze down both noxious phytoplankton species, even when provided a unialgal diet. Clearance rate was affected by A. carterae but not by the brown tide organism. Ribbed mussels may play an important role in regulating the abundance of harmful algae even if toxic effects are present.