Accumulation of lead in the tissues of freshwater catfish Clarias gariepinus exposed to static nominal concentrations of lead nitrate

Abstract

Static bioassay methods were used under laboratory conditions to determine the accumulation of lead by Clarias gariepinus. The C. gariepinus fingerlings were exposed to sublethal analar grade of lead nitrate solution. The levels of lead in the samples were determined by Atomic Absorption Spectroscopy. The amount of lead accumulated by C. gariepinus was found to be a function of the concentration of lead in the water in which the test C. gariepinus were maintained and duration of exposure. After 8 weeks of exposure, to 0.032, 0.052, and 0.160 mgl-1 the accumulated lead was 12.63, 26.94, and 33.49 Ugg-1 (fresh weight) respectively. The lead was found to be accumulated to different levels by the different tissues analysed. The order of accumulation was gill > liver > muscles. The high level of lead in the lead in the gill might not be unconnected with externally bound lead from the medium rather than internally bound lead to the gill. The increase lead concentration recorded in the control fish could be due to lead in their food (feed) or the lead present in the well water to which the fish were exposed in this study.