Spatial and temporal variation in fish community structure of a marine embayment in Zanzibar, Tanzania

Abstract

Spatial-temporal variations in the fish community structure were studied from a tropical non-estuarine embayment in Chwaka Bay, Zanzibar. Fish samples were collected bimonthly for 1 yr from mangroves, mud/sand flats and seagrass beds. Environmental variables were examined to determine their relationship with fish the community structure. The fish community structure together with the environmental variables in mangroves and mud/sand flats remained constant for most part of the year; however, a marked decline in fish densities, biomass, and species richness and in environmental variables was observed during the rainy period. A significant relationship was found between density and species richness of fish, and temperature, salinity, and water clarity. Salinity was the most conspicuously changing environmental variable with seasons; we therefore propose that, salinity alone or in combination with the other environmental variables, was probably the most important environmental factor structuring the fish assemblage in the mangroves and mud/sand flats habitats.