Distribution and abundance of demersal fishes and of some other marine benthic organisms on the continental shelf (0-60 m) of French Guiana.

In order to establish the distribution and abundance of demersal fishes and of some other benthic organisms on the continental shelf of French Guiana (western central Atlantic), ninety-five bottom trawls were effected at dept hs ranging from 0 to 60 m in October 1993. A total of one hundred and ten d ifferent species were identified including eight decapod crustaceans, two c ephalopods, one sea turtle and ninety-nine fishes. Despite the high species richness in benthic macrofauna, most species showed a low count. rind only twelve of them comprised more than 80 % of total captures. This study has mainly highlighted the existence of a well-pronounced bathymetric zonation. This phenomenon would appear to be linked to environmental factors, especi ally salinity and substrate granulometry, which are greatly conditioned by fresh a ater and sediment flowing in large rivers such the Amazon River. Th e results revealed three distinct faunistic assemblages: a littoral (or sha llow-water) community (0-30 m) distributed in coastal estuarine waters char acterized by muddy bottoms, a middle-shelf community (30-50 m), and a lower -shelf community (depths > 50 m) distributed in deeper marine waters charac terized by sandy bottoms. (C) 2000 Academie des sciences/ Editions scientif iques et medicales Elsevier SAS.