Low levels of heavy metals in shrimps (Decapoda: Atyidae) from Omodo River in southern Nigeria

Abstract

Shrimps remain an important source of proteins worldwide. The contamination of the environments with effluence such as from domestic, healthcare systems, industrial waste discharges and agricultural run-offs; are posing much danger to the consumption of shrimp diets by humans in particular. The ingestion of heavy metals from sediment and in water column is chiefly the source of contamination to the shrimps. This study was conducted quarterly and spanned from December, 2012 to May, 2014 with the objectives to determining the background levels of eight heavy metals in whole body mass of crustacean (Caridina africana and C. gabonesis) as well as in the sediments. Standard methods were employed in the sampling and analyses. The results obtained for heavy metals in sediments were in folds higher than what were obtained in the shrimps tissues. The mean range of concentrations of metals in the sediment across the stations were in the order; Zn (15.076-18.182 mg kg^-1) > Cu (6.146 - 8.130 mg kg^-1) > Pb (0.131-0.198 mg Kg^-1) > Co (0.033-0.045mg kg^-1) > Cr (0.017-0.028mg kg^-1) > Cd (0.002-0.010mg kg^-1) > Ni (0.003-0.008 mg kg^-1) > V (0.001 mg kg^-1). The values of heavy metals in shrimps as obtained in this study were far below the limit stipulated by Food and Agricultural Organisation (FAO) and have indeed confirmed the non-industrial waste disposal into the water bodies in Agbede-wetlands including Omodo River.

Keywords: Analysis; Agbede; concentrations; ingestion; sediment; shrimps