delta C-13 versus delta N-15 of co-occurring molluscs within a community dominated by Crassostrea gigas and Crepidula fornicata (Oosterschelde, The Netherlands)

The aim of this study was to investigate, by use of delta(13)C and delta(15)N, the diet of co-occurring intertidal molluscs species within a community dominated by the oyster Crassostrea gigas and its epibiont, the common Atlantic slipper limpet Crepidula fornicata. The results showed that the delta(13)C versus delta(15)N values of C. gigas differed from those of the deposit feeders considered but also from the other suspension-feeding molluscs (i.e. Mytilus edulis, Cerastoderma edule and C. fornicata), being more depleted in C-13 and in N-15. The results suggest more similarities in the assimilated food sources of C fornicata, C. edule and M. edulis. In particular, the delta(13)C and delta(15)N differences between C. gigas and C. fornicata suggest that these associated suspension feeders in many shellfish culture areas may not necessarily be competitors for food sources when food is not limited.