Heavy metals contamination of Chrysichthys nigrodigitatus and Lates niloticus in Ikere Gorge, Oyo state, Nigeria

Abstract

This study investigates the presence of heavy metal contamination of Chrysichthys nigrodigitatus and Lates niloticus. Adult C. nigrodigitatus and L. niloticus were obtained from fishermen in Ikere Gorge, Oyo state, Nigeria. Water samples were also collected during the wet and dry seasons of the year in the same locality. The presence of five metals were analyzed in both fish and water. Iron, copper, zinc, lead and manganese were investigated by atomic absorption spectrosocopy (AAS) in two separate experiments. In each case, four tissues; gills, bone, intestine and muscle were compared with the level of metals in the water. Lower concentrations of metals were recorded in water than in fish. Lower concentration of the metals found in fish and water was less than that recommended by the World Health Organisation (WHO) guideline for maximum concentration recorded in the tissue of the two samples. Iron was found to be dominant in the intestine of C. nigrodigitatus, while manganese was found to be highest in the bone of L. niloticus, copper recorded the least of all the metals. There is significant difference (P < 0.05) in heavy metals concentration in the gill of C. niloticus and water, as well as the concentration in the intestine of L. niloticus and water. It was concluded that though the heavy metals of interest were present in measurable quantities, they were still within safe limits for consumption.

Key words: Heavy metals, fish, gorge, contamination.