Meeting Abstract
P1.5 Monday, Jan. 4 Predicting the impacts of fluctuating bivalve densities on phytoplankton communities PERINO, LAURIE L**; MUNCH, STEVEN B; PADILLA, DIANNA K; Stony Brook University; Stony Brook University; Stony Brook University lperino@ic.sunysb.edu
Suspension-feeding bivalves have the potential to control phytoplankton communities both in biomass and species composition. Understanding this relationship is becoming increasingly important as eutrophication is leading to more severe phytoplankton blooms, including harmful algal blooms, which cause hypoxic and anoxic events. To assess the potential impacts of bivalves on the phytoplankton community we need a scientifically based, quantitative method to predict possible changes. To address this issue, we constructed a simple ecological model to predict the extent to which different densities of bivalves can have control over phytoplankton growth and species composition. Models such as this can be important tools for ecosystem-based management, making decisions about harvest limits and restoration goals, predicting impacts from exotic introductions, and for examining the potential for suspension feeders to control blooms of harmful algae. We parameterized our model using species from waters on Long Island, NY. We used Mercenaria mercenaria, a dominant species along the entire east coast of the United States and the current target for restoration efforts, as the suspension-feeding bivalve. We also used three common species of phytoplankton, Nitzschia closterium (20µm), Thalassiosira pseudonanna (5µm), and Aureococcus anophagefferens (2µm). We used A. anophagefferens because it is a harmful alga that has been blooming in Long Island waters and is believed to be hampering bivalve restoration efforts. We ran simulations of the model over a range of clam densities. The results showed a threshold response to increasing clam density. At an approximate density of 2 clams/m2, the density of phytoplankton began to fall drastically until a density of 4 clams/m2, when the degree of phytoplankton decrease leveled off.
