Observations on the benthic macroinvertebrate and fish communities of the Kakum Estuary Wetland in Ghana

Abstract

The environmental conditions, composition of benthic macrofauna, and richness, diversity, as well as food habits and aspects of reproductive biology of fish species in the Kakum Estuary wetland (located 2 km west of Cape Coast, Ghana) were studied from July 2009 to February 2010 in an effort to broaden our knowledge of the biodiversity and ecological value of wetland ecosystems. Sampling was conducted on five pools in the wetland. Oligochaeta and Diptera (chironomid larvae) were the only benthic organisms present, presumably because of the ephemeral nature of the environment. During the dry season, the organisms declined significantly in abundance and densities and later disappeared, possibly due to the continuously increasing salinity which rendered the environment stressful to the organisms. Twelve families of eighteen genera comprising eighteen fish species were collected, of which Aplocheilichthys spilauchen (43.31%), Sarotherodon melanotheron (18.12%) and the freshwater shrimp Macrobrachium macrobrachion (12.37%) were dominant. Results suggested that marine and freshwater fishes use the wetland as nursery and feeding grounds. The fish communities included planktivorous, carnivorous and omnivorous ones. Kribia kribensis and Porogobius schlegelii had high fecundities suggesting that they provide little or no parental care while S. melanotheron and A. spilauchen had low fecundities which were attributable to their adaptations for ensuring survival of their spawn. Some recommendations have been made including restriction on fishing during the wet season to avoid exploitation of juvenile fishes.