Bioaccumulation of Heavy Metals in Fish (Hydrocynus forskahlii, Hyperopisus bebe occidentalis and Clarias gariepinus) Organs in Downstream Ogun Coastal Water, Nigeria

Abstract

In this study accumulation of some heavy metals Cadmium (Cd), Chromium (Cr), Cobalt (Co), Nickel (Ni) and Lead (Pb) in the operculum, gills, heart, kidney, muscle and vertebrae were determined in some fishes (Hydrocynus forskahlii, Hyperopisus bebe occidentalis and Clarias gariepinus) collected from fishermen around Ogun estuary. The accumulation of the metals in different organs showed significant differences (P<0.05) except lead accumulation. However, the bioaccumulation of the heavy metals was species-related as the accumulations of the heavy metals analysed in the sampled fishes were of the following trend: H. forskahlii > H. bebe occidentalis > C. gariepinus and the pattern of distribution was Ni > Cr > Co > Cd > Pb for all the fish species. The levels of Ni and Cr in this study were higher than the maximum permissible limits (FAO, UNEP, FEPA and WHO) for human consumption and that of Cd, Pb and Co were still lower. Safe disposals of domestic sewage and industrial effluents as well as enforcement of laws enacted to protect our environment are therefore advocated.