CONCENTRATION OF HEAVY METALS IN THREE AFRICAN PRAWNS (CRUSTACEA: PALAEMONIDAE) FROM OVIA RIVER IN EDO STATE, NIGERIA

Abstract

Heavy metals concentrations in three African prawns sampled at three sites along Ovia river bank in Edo State were investigated by means of an atomic absorption spectrophotometer. The combined mean values of Pb, Ni, Fe, Cr, Mn and V in the prawn samples are presented in the following ranges: Macrobrachium macrobrachion- Pb (0.00-0.250 mg/kg), Ni (0.00-0.250mg/kg), Fe (0.560-0.631mg/kg) Cr(0.00-0.210mg/kg, Mn (0.850-2.250mg/kg) and V (0.00-0.033mg/kg). M. felicinium- Pb (0.00-1.50mg/kg), Ni (0.00-0.145mg/kg), Fe (0.105-1.510mg/kg), Cr (0.00-0.350mg/kg), Mn (0.156-1.320mg/kg), and V(0.00-0.10mg/kg). M. vollenhovenii- Pb (0.105-1.360mg/kg), Ni (0.103-0.210mg/kg), Fe (0.535-2.450mg/kg), Cr (0.013-0.230mg/kg), Mn (0.652-0.835mg/kg) and V (0.00-1.050mg/kg). No significant differences (P>0.05) were recorded between the concentrations of Fe and Mn in the prawn samples caught at the three study sites. The marginal high concentrations of Ni, Fe and Mn in the prawn samples are higher than recommended values in fish and fishery products by the Food and Agricultural Organization (FAO) and the World Health Organisation, (WHO). An evaluation of the possible risks associated with prawns contaminated with these metals could be deduced from this study. Findings from this study necessitate the need for caution in the discharge of pollutants into the Ovia river.