Factors affecting macrobenthic fauna in a tropical hypersaline Coastal Lagoon in Ghana, West Africa

Abstract

The macrobenthic fauna in the large, hypersaline, shallow Keta Lagoon in Ghana was sampled at 20 stations in the set (September, 2002) and dry seasons (March, 2003) to elucidate the effects of abiotic factors on community patterns. The macrobenthic fauna was low in density and species diversity and numerically dominated by bivalves and capitellid polychaetes. These organisms appear able to withstand physical disturbance (when legoon water levels become extremely low) and osmotic stress (when slinities are extremely high) and tend to redistribute along environmental gradients. Parallel seasonal difference in several environmental variables and the macrobenthic fauna indicate a highly dynamic system. Species richness and diversity were higher in the wet season than the dry season. Salinity, percent clay, pH, and turbidity in that order were the major significant variable structuring the macrobenthic faunal assemblage in Keta Lagoon. The strong effect of seasonal salinity charges on macrobenthic faunal assemblage may have tropic consequences for higher organisms of commercial importance, such as fishes and shorebirds, in the Keta Lagoon.