Heavy metal bioaccumulation in Callinectes amnicola and Farfantepenaeus notialis from three selected tropical water bodies in Lagos, Nigeria.

Abstract

The bioaccumulation of heavy metals in organisms is as a result of pollutants discharge generated by anthropogenic and natural activities which has become a tremendous concern in developing nations. The levels of cadmium, copper, chromium, lead, zinc and nickel in the tissue of Callinectes amnicola and Farfantepenaeus notialis collected from Igbese River, Makoko and Lekki Lagoon were evaluated for a period of eight months. Heavy metals analysis was done using Atomic Absorption Spectrophotometer. The mean concentration values of heavy metals in the tissues of lagoon crab recorded are-Cr (0.14, 0.71 and 0.19 mg/l), Cu (2.17, 1.27, 1.51 mg/l), Pb (0.47, 0.26, 0.15 mg/l), Zn (0.04, 1.05, 0.63 mg/l), Ni (0.33, 0.30, 0.19 mg/l) in Igbese River, Makoko site and Lekki Lagoon respectively. While metal concentration in tissue of shrimps observed are-Cr (0.28, 0.18 and 0.14)mg/l, Cu (1.21, 1.03, 0.56) mg/l, Pb (0.26, 0.19, 0.13) mg/l, Zn (0.74, 1.11, 0.36) mg/l, Ni (0.28, 0.27, 0.15) mg/l across Igbese river, Makoko site and Lekki lagoon respectively. There was a significant difference (P<0.05) observed in Cr and Pb of the lagoon crab. The bioaccumulation factor was found highest in the pink shrimp at Makoko with an increasing order of Pb > Ni > Zn > Cr > Cu > Cd. The bioaccumulation factor (BAF) of the metal from sediments to tissues of lagoon crabs and shrimps observed highest accumulation in comparisonwith water to tissues. The observed metals with higher BAF values were Pb (0.81, 1.82 and 1.60) in lagoon crabs and Pb (1.46, 2.68 and 2.00) in shrimps and Zn (1.23, 1.01 and 1.32) in lagoon crabs and Zn (1.73, 0.95 and 2.31) in shrimp's bioaccumulated from sediment across Igbese river, Makoko site and Lekki Lagoon respectively. While the least BAF metal was Cu with values of 0.03, 0.12 and 0.03 in lagoon crabs and 0.06, 0.15 and 0.09 in shrimp's bioaccumulated from water across Igbese river, Makoko site and Lekki Lagoon respectively. The results revealed that heavy metals concentrations in the lagoon crab and pink shrimp were below the threshold levels associated with toxicological effects and regulatory permissible limits.

Key words: Bioaccumulation, Callinectes amnicola, Heavy metals, Lagoons, Farfantepenaeus notialis,