Biodiversity and assemblages of molluscs (Gastropoda and Bivalvia) from coastal and deep-sea soft-bottoms off Mauritania

The collections as well as quantitative faunistic and environmental data obtained from 384 bottom-trawling stations during the four Spanish Maurit and two FAO–CCLME expeditions have allowed us, for the first time, to establish the biodiversity distribution patterns and assemblage structures of Mauritanian molluscs. The six surveys prospected the soft-bottoms of the shelf and continental slope between Cape Blanc (20°50′N) and the Senegalese border (16°04′N), from a depth of 19 to 1860 m. Almost 13,000 live specimens collected from 150 stations (40% of the total) belonged to 104 species (37 bivalves and 67 gastropods). Nassariidae and Xenophoridae were the most frequently found families, and the gastropod Nassarius wolffi (Knudsen, 1956) was the most frequent mollusc species in the Mauritanian soft-bottoms. Naticidae and Marginellidae, followed by Muricidae and Pectinidae, were the most diverse families.