Accumulation of Heavy Metals in Water, Sediment and Fish Species in Ologe, Lagoon
Fish inhabiting a polluted aquatic ecosystem tend to accumulate heavy metals in their tissues. Generally, accumulation depends on metal concentration, time of exposure, way of metal uptake, environmental conditions and intrinsic factors. This study was to investigate the metal accumulation in Sarotherodon melanotheron and Chrysichthys nigrodigitatus from the water and sediments at Ologe Lagoon for period of six months (April – September, 2014). The physicochemical parameters were determined according to AOAC and heavy metals such as zinc (Zn), copper (Cu), lead (Pb), Nickel (Ni) and chromium (Cr) were determined using Atomic Absorption Spectrometry. The sequence of Bioaccumulation factor (BAF) for Sarotherodon melanotheron: Cr > Zn > Cd > Pb > Cu; while for Chrysichthys nigrodigitatus: Cu > Cr > Pb > Cd > Zn. The study showed that generally the metal concentration in the water and sediments bio accumulated in Chrysichthys nigrodigitatus and Sarotherodon melanotheron are higher in Cr, Cu, Zn, and Cd. While the Ni and Pb are less in the tissues and are regarded to be safe by WHO and FEPA. Fish at the Ologe Lagoon are still consumable though partially contaminated with slight increase in heavy metals influenced by anthropogenic activities. However, it is quite evident that there was bioaccumulation of heavy metals in fish tissues and condition may get worse. Therefore, a regular monitoring of heavy metal levels in fishes is necessary.