Distribution of the twenty seven dominant species of shelf benthic foraminifers on the continental shelf, north of Dakar (Senegal)

Abstract

One hundred and thirty-one samples were collected on the shelf and on the uppermost slope (down to 180 m) off Northern Senegal, between 14 °50′ and 16 °20′ N latitude. Two hundred and three species of benthic foraminifers were recognized. Most of them were reported in previous works, along the coast of Africa. Twenty seven species are selected for detailed analysis and distribution maps are given for each of them. Q mode and R mode statistical analyses were performed on these selected species. The distribution is mainly related to depth; the second factor of distribution is the nature of the sediments: about 30% of the study area is covered by the muddy sediments of the pro-delta of the Senegal river. Hierarchical analysis shows that the main limit in the pattern of change of these 27 species with depth is about 60–65 m. A depth index Di, calculated on the basis of twelve selected species, gives a depth indication with a precision of about 40 m over the shelf. It is possible to envisage a possible use of this index for the investigation of Quaternary sea-level changes.