| Stock assessment of wild soft-bottom molluscs formed part of a study carried out in the Marennes-Oléron oyster-farming bay. The sampling design was based on a stratified random sampling. The results are presented using three descriptors: species richness, abundance and biomass. In spring 1984, wild molluscs corresponded to nearly 20% of oyster-rearing stocks. Knowledge of the feeding behaviour and geographical distribution of the various trophic groups within the bay enables to estimate trophic competition with the cultivated species (Crassostrea gigas and Mytilus edulis). Five trophic groups were specified: suspension-feeders, deposit-feeders, suspension/deposit feeders, carnivores and herbivores. Their organization in terms of species number seemed to... |
