Contribution to a synopsis of marine species richness in the Pertuis Charentais Sea with new insights in soft-bottom macrofauna of the Marennes-Oléron Bay

The catalogue of soft-bottom macrofauna in the Marennes-Oleron Bay (French Atlantic coast) has been updated from a benthic survey conducted in April-May 1995. 262 stations were selected using a stratified random strategy based on sediment types and bathymetric levels. 231 soft-bottom macrofauna species were identified. A synopsis of all available literature since the first local marine study published in 1710 by Antoine Ferchauld de Reaumur indicated that 60 benthic species were reported in the Marennes-Oleron Bay for the first time. The sampling effort, i.e. more than 1 station per km(2) and size of the sieving square mesh (1 mm), can partially explain these results. Most of the new recorded species were crustaceans (28 species) and polychaete annelids (25 species) for only five molluscs. First report of Ocinebrellus inornatus, Mollusca Gastropoda, should be noted for the European Atlantic coasts. Additionally, alteration of subtidal habitats, colonized by Crepidula fornicata Linnaeus (Mollusca, Gastropoda) since the 1970's, may also have facilitated the recruitment and spread of some annelid polychaetes which were not previously reported in the Marennes-Oleron Bay. The total number of macrofauna species in the Pertuis Charentais Sea is 858.