Preliminary study on the composition and abundance of shellfish (Decapoda: Crustacea) in Uta Ewa Estuary, Ikot Abasi Local Government Area, Akwa Ibom State, Nigeria

Abstract

The study, Preliminary Study on the Composition and Abundance of Shellfish: Decapoda: Crustacea, in Uta Ewa Estuary was carried out between January and May 2012. The physico-chemical parameters of the water were measured in situ using standard methods according to APHA, AWWA and WEF (1998). Shellfish specimens were sampled monthly. Air- and water-temperature ranged from 27.9 – 31.6 oc and 28.2 – 28.9 oc respectively, while DO, pH and salinity were between 3.28 – 4.09 mg/L, 6.40 – 7.7 ppm and 0.00 – 12.9 ppm respectively. The mean values of the physico-chemical parameters measured were not significant at r = 0.456. Pandalus sp. was the most abundant in station 1 accounting for 50.29 %, followed by Nematopalaemon hastatus which accounted for 29.21 % , while in station 2, N. hastatus was the most abundant, accounting for 39.78 %, followed by Pandalus sp. accounting for 31.40 % of the relative abundance. Panopeus africanus was the least collected shellfish species, it accounted for 0.14 % in station 1 and 0.45 % for station 2. Station 2 had shellfish Shannon diversity of 1.54 while station 1 had 1.31. The physico-chemical parameters showed significant relationship with the abundance of the shellfish species (p<0.05). The results of air- and water-temperature and pH were within limits of stipulated minimum values of the National Environmental Standards and Regulations Enforcement Agencies (NESREA) for aquatic life. Uta Ewa estuary is rich with a wide variety of shellfish species of ecological and economical importance; hence the coastal area should be monitored and protected from pollution.

Keywords: Shellfish, Decapoda, Uta Ewa estuary, Composition, Abundance