THE DISTRIBUTION OF BENTHIC MOLLUSKS IN A COASTAL LAGOON IN BENIN (WEST AFRICA)

Eleven species (5 bivalves and 6 gastropods) were recorded in a survey of the molluscs of Lake Aheme, a West African lagoon in the south of Benin. A correspondence analysis was carried out on the distribution and abundance of the populations from 62 sampling stations, according to salinity, bottom structure and depth. The biocenotic zonation was strongly influenced by the superposition of two internal gradients, a gradient of decreasing salinity from south to north and a gradient of sedimentation (particle size decreasing from the banks to the central zone of the lake). An analysis of the distribution of each species showed its environmental preferendum and typological range. After discussion, a map of mollusc habitats in Lake Aheme is proposed.