Variations in food intake of Pecten maximus (L.) from the Bay of Brest (France): influence of environmental factors and phytoplankton species composition.

Previous studies carried out in the bay of Brest on daily shell growth of Pecten maximus have demonstrated that temperature is a major control on daily shell growth in contrast to food supply. However, repeated events of slow growth have been observed during diatom and dinoflagellate blooms. The aim of this study was to determine how fluctuations in environmental parameters influence P. maximus food intake and daily shell growth rate. In 1995, P. maximus food intake and growth were highest when Cerataulina pelagica (diatom) blooms occurred and lowest during Gymnodinium cf. nagasakiense (dinoflagellate) blooms. During blooms of other diatom species, P. maximus food intake and growth were high when the algal concentration did not exceed a critical threshold, dependent upon the dominant species and sedimentation rate of diatoms. These results demonstrate that the morphological and physiological features of phytoplankton bloom species strongly affect benthic microphytophagy, a component of benthic-pelagic coupling.