The abundance and composition of crabs (Decapoda) in Uta Ewa brackish water, Akwa Ibom State, South-South, Nigeria

Abstract

Study on the abundance and composition of crabs in Uta Ewa brackish water was carried out between January and May 2012 at two sampling stations. The physicochemical parameters of the water were measured in situ using standard methods according to APHA (1998). Crabs species were collected at two sampling stations using square lift net trap, while at low tide, crab species were collected by hand-picking at random and preserved in a chest box for identification. Air and Water temperature ranges from 27.9-31.6 oC and 28.2-28.9 oC respectively, while Dissolved Oxygen and Salinity were between 3.28-4.09 mg/L and 7.5-12.9 ppt respectively. The results of the physicochemical parameters were within limits of the National Environmental Standards and Regulations Enforcement Agencies for aquatic life. A total of 107 crabs were collected from the two sampling stations. Goniopsis pelii was the most abundant in Station 1 accounting for 57.9%, followed by Callinectes amnicola 26.3%, while in Station 2, Callinectes amnicola was the most abundant accounting for 46.6% of the percentage abundance. Station 2 had the highest Shannon diversity index of 1.22, while Station 1 had 1.15. The abundance and composition of crab species in the study areas is an indication that the area is an important ecological zone for benthos macroinvertebrates conservation. Keywords: Uta Ewa, Brackish Water, Physicochemical Parameters, Abundance, Composition, Crab species,