Roland Efe Uwadiae, Clement Aghatise Edokpayi, Oyinade Adegbite and Omosalewa Ablmbola
Abstract
The physico-chemical characteristics of the sediments and the benthic macrfauna of Epe lagoon, in south-western Nigeria were investigated between September, 2004 and February, 2005. The sediment parameters studied were grain size, total organic content (TOC), pH, conductivity, nitrate, phosphate, sulphate and heavy metals (zinc and copper). A range of 65.8-92.8% for sand, 7.8-29.4°/0 for mud, 2.05- 98.5% for TOC ,7.2-8.0 for pH, 3.81-44.27mg/kg for zinc, 0.32-5.81mg/ kg for copper, 0.10-0.19mg/ kg for sulphate, 1.12-1.38mg/ kg for nitrate, and 0.22-0.35mg/ kg for phosphate were recorded during the study period. Sediment types were predominantly sand intermixed with varied proportions of mud. There was significant difference (ANOVA, P<0.05) in all the parameters investigated at the study stations except for phosphate and nitrate. A total of 2,673 individuals belonging to three phyla (Annelida, Arthropoda and mollusca) were encountered in this study. The molluscs dominated both in the number of individuals and species. The benthic macroinvertebrates abundance and diversity were low. The impact of sediment characteristics on the distribution, abundance and diversity of benthic macroinvertebrates in the study area is discussed.