Toxicologie environnementale et analytique

Levels of Heavy Metal in Some Selected Fish Species Inhabiting Ondo State Coastal Waters, Nigeria

Abstract

Johnson Olayinka Olusola and Aiyesanmi Ademola Festus

The distribution and level of six heavy metals viz: Cr, Cd, Pd, Cu, Zn, and Ni in different organs gill, head, bone, muscle and eye of five fish species Arius latisculatus, Cynoglossus browni, Caranx lugubris, Sardinella aurita, Caranx senegallus, and associated water collected from the coastal waters of Ondo State, Southwestern Nigeria were investigated in this study. The concentrations of Zn (0.10-0.36 mg/kg), Cu (0.18-0.27 mg/kg), Ni (BDL-0.01 mg/kg) and Cr (0.04-0.63 mg/kg) found in the water samples were within the Maximum Permissible Level (MPL), while higher concentrations above the MPL were recorded for Cd (0.08-0.19 mg/kg) and Pb (0.34-0.79 mg/kg). Zn was the most abundant heavy metals found in all fish species organs investigated. Higher concentrations of the metals were recorded in the gills and eyes compared to other organs in most of the fish species. While the concentration of Zn (0.28 mg/ kg-4.14 mg/kg), Cu (BDL-5.72 mg/kg), Ni (BDL-0.01 mg/kg), and Cr (BDL-3.41) in the fish tissues were within the Maximum Allowable Level (MAL) for a food source, the findings of this study Cd (BDL-3.18 mg/kg) and Pd (BDL-1.14 mg/kg) showed values exceeding the maximum allowable level, thus constituting potential health hazard to consumers of these fish species. Transfer factors of most metals in fish from water were greater than or equal to 1 suggesting bioaccumulation of the metals by the fish from water column, while distribution of the heavy metals in the different fish parts were organ specific.