Structure and dynamics of demersal assemblages on the continental shelf and upper slope off Ghana, West Africa

Using two-way indicator species analysis and detrended correspondence analy sis, species on the continental shelf and upper slope of Ghana were classif ied into 6 assemblages. The structure of the assemblages is determined prim arily by depth and type of sediment on the seabed. There are dear faunal di scontinuities around 30-40, 100 and 200 m depth. The dynamics of the assemb lages axe influenced by physico-chemical parameters of the water masses, ma inly temperature, salinity and dissolved oxygen, which are periodically mod ified by the seasonal coastal upwelling that occurs in the area, The observ ed changes in the composition and relative importance of species in the ass emblages can be related to increased fishing activity and environmental for cing.