Trophic ecology of filter feeders under other food particles different than phytoplankton

TATIÁN, MARCOS; LAGGER, CRISTIAN; DEMARCHI MILAGROS; QUARTINO, LILIANA; SAHADE, RICARDO; SERVETTO NATALIA; TORRE, LUCIANA; VARELA, MERCEDES; MERCURI, GUILLERMO

Congreso; . Scientific Committee on Antarctic Research (SCAR); 2010

A rich benthic community dominated by filter-feeders occupies the shallow areas of Potter Cove, in spite of which may seem certain unfavorable conditions for their feeding activities. These include high inorganic sedimentation (mainly during summer) and low pelagic primary production. The intake of a wide spectrum of food particles was stated to be the strategy for filter-feeders to maintain their high secondary biomass. For instance macroalgal debris, were detected in the water-bottom interface year-round and used by filter feeders: relatively high assimilation efficiencies were estimated in aquarium experiments, when different sizes of particulate macroalgal fragments under different inorganic particulate loads were tested in one clam and in two ascidian species. Estimated particle flux (feces) produced by ascidians varied according to species, being the C:N ratio of feces relatively high, as compared with other filter-feeding organisms. Experiments testing the intake of macroalgal debris after some time of in situ degradation, reflects more accurately the real particulate material that may be available to filter-feeders. In spite of the low rate of degradation observed in macroalgae, the associated bacterial community could enrich the organic and particularly the nitrogen content of both, the food for filter feeders and the feces produced by these animals, allowing their re-utilization by other benthic fauna.