ABSTRACT
Heavy metals, such as lead, cadmium, nickel, cobalt and chromium are pervasive environmental pollutants. These toxic substances enter water bodies through various anthropogenic activities, including industrial discharges, agricultural runoff, and urbanization potentially leading to the accumulation in aquatic organisms. This study evaluated the organ-specific uptake of heavy metals in benthic and pelagic fishes of Ikpoba river. Two species of fishes was selected based on their ecological importance, abundance, and potential exposure to heavy metal contamination, Tilapia zilli representing pelagic and Clarias gariepinus representing benthic. The liver, gills, muscle and gonads was analyzed for heavy metals (lead, cadmium, Nickel, cobalt and chromium) using standard method. Results showed that the levels of metals in the fishes were higher than that in the surrounding waters and sediment. The distribution of lead, cadmium, nickel, cobalt and chromium across fish organs showed significant variations with the gills-(0.51 mg/kg) having the highest concentration and gonads-(0.11mg/kg) having the lowest. Heavy metal concentration in the fish organs (gills-0.51 mg/kg,muscles-0.25mg/kg, liver0.24mg/kg,brains-0.15mg/kg, and gonads-0.11mg/kg) was in the order gill>muscles>liver>brains>gonads in the various fish species. The mean concentrations of nickel recorded in the gills-1.48mg/kg and muscles-0.07mg/kg of fish organs in this study exceeded the permissible limits for nickel (0.5–0.6 mg/kg) set by WHO for fish and fishery products. Furthermore, the mean concentration of lead in the brains-0.15mg/kg and gills-0.122mg/kg also exceeded the permissible limits for lead (0.05mg/kg) set by WHO. The presence of elevated heavy metal concentrations in fish organs raises concerns because of its ecological impacts and potential risks to human populations relying on these organisms as a food source.
