THE FINE SAND ABRA ALBA COMMUNITY OF THE BAY OF MORLAIX 20 YEARS AFTER THE AMOCO-CADIZ OIL-SPILL

The fine sand Abra alba community from the Bay of Morlaix (western Eng lish Channel) was strongly affected by the Amoco Cadiz oil spill of Ap ril 1978. The long term changes in the community (1977-1996) show that reconstitution of this community is slow lover 10 yr). A progressive recolonization by amphipod Ampelisca populations constituting the domi nant species is observed. The results show that it is necessary to sur vey the affected communities for a long period of time ( > 10 yr) afte r an event to identify the real ecological impact of an oil spill. The abiotic and biotic factors existing in the Bay of Morlaix are favorab le to the establishment and the persistence of stable dominant Ampelis ca populations in time. The 'climax' concept seems to be applicable to this type of stable environment. The soft-bottom Abra alba community of the Bay of Morlaix may only support a maximal carrying capacity of approximately 10-11 g m(-2) (mean annual biomass in decalcified dry we ight). The deficit of production during 11 annual cycles may have affe cted the fish biomass feeding on this community. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.