MALAPTERURUS ELECTRICUS, (GMELIN 1789), AND ITS PARASITES, AS HEAVY METAL BIOMONITORS IN LEKKI LAGOON, NIGERIA

Abstract

The concentration of some heavy metals, Lead, Nickel, Zinc and Iron from the waters, sediment and liver of Malapterurus electricus collected from Lekki Lagoon were investigated. The parasites found inside M.electricus were also investigated for these metals. The concentration of Pb, Ni, Zn and Fe in the liver of M . electricus exceeded the WHO (1993) approved limits and were significantly higher (P<0.01) than those found in the water and sediment of the Lagoon (Pb, 0.976 + 0.79mg/kg, Fe, 24.54 + 55.07mg/kg, Zn, 6.83 + 8.20mg/kg and Ni, 34.20 + 6.26mg/kg). The concentration of Ni (0.089 + 0.050mg/kg), Zn (0.80 + 0.036mg/kg) and Fe (0.950 + 0.030mg/kg) were higher in the sediment than the water samples (Ni, 0.039 + 0.004mg/kg, Zn, 0.175 + 0.019mg/kg and Fe, 0.150 + 0.028mg/kg). The bioaccumulation factors showed that the trend of metal accumulation from the water and sediment and the liver of M. electricus was Fe > Pb > Zn > Ni. Concentrations of Pb, Fe and Zn were higher in females than male, although not significant. M. electricus with condition factors lower than 1.4 (< 1.4) accumulated more of Pb, Zn and Ni while those with condition factor greater than 1.4 (> 1.4) accumulated only Fe. The parasito fauna of M. electricus includes Electrotaenia malopteruri, ( Cestoda) and Procamallanus longus (Nematoda). Both E. malopteruri and P. longus accumulated more heavy metals than the liver of M. electricus. E. malopteruri accumulated 8.6 times more Pb, 3 times more Fe, 43 times more Zn and 4 times more Ni while P. longus accumulated 8.5 times more Pb, 4 times more Fe, 27 times more Zn and 5 times more Nickel than the liver of M . electricus. Bioaccumulation of heavy metals in tissues of fin fish poses a significant threat to the health of end users. Continuous bio monitoring of aquatic ecosystems and enforcement of regulatory laws is therefore essential