The evolution of microbial biomass based on chlorophyll a, pheopigments, proteins, particulate carbon and nitrogen, ATP and total viable aerobic bacterias measurements, is studied on three oyster ponds in relation with different densities of reared oysters Crassostrea gigas (Thunberg). Chlorophyll a important amounts characteristics of theses middles (13 to 100µg.1(1) are in part consumed when the density of oysters is important, comparatively ATP increase to 30µg.1(1). With important values of (ATP/carbon) 10(3) ratios, upper than 10, we could think that the development of large silicified phytoplanktonic species should be favoured by oysters particularly the diatom Navicula ostrearia (Bory) |