FOOD SOURCE OF INTERTIDAL NEMATODES IN THE BAY OF MARENNES-OLERON (FRANCE), AS DETERMINED BY DUAL STABLE-ISOTOPE ANALYSIS

Nematodes living on an intertidal mudflat of the Marennes-Oleron Bay ( France) were assayed for delta(13)C and delta(15)N ratios together wit h their potential food resources between July 1992 and May 1993. Resul ts suggest that nematodes do not exploit all the components of the sed imented organic matter (SOM) pool at the same rate. Furthermore, based on coefficients of average trophic enrichment found in the literature for both C and N, the enrichment of nematodes in C-13 and their deple tion in N-15 relative to SOM suggest that microphytobenthos constitute s their main food source in this particular environment.