ECOTOXICOLOGICAL RISK RANKING OF DISPERSANT, CONDENSATE AND OIL-BASED MUD ON AFRICAN CATFISH, (Clarias gariepinus).

Abstract

The toxic effects of dispersant (Biosolve), condensate, and oil based mud on African catfish (Clarias gariepinus) of average weight 56.4 ± 31.1 g and length 18.5 ± 3.50 cm were examined. The acute toxicity tests were carried out according to the static non-renewable bioassay procedure. The experimental design consisted of a set of five triplicate sets of concentrations (100, 200, 300, 400, 500 mg/L, and a control set up (0 mg/L) of  dispersant, condensate, and oil based mud; in separate 30 liter capacity calibrated rectangular tanks, each filled up to the 15 liter mark. Each tank was distinctively labeled and loaded with 10 tests organism, making a total of 540-fishes. This study investigates the toxic effects of three different petroleum based chemicals: dispersant, condensate, and oil based mud on Clarias gariepinus by determining their respective 96-hour LC50 value. The 96 hrs LC50 of was found to be 51.3 mg/l., 42.3 mg/l and 28.9 mg/l for dispersant, condensate and oil based mud respectively. The parameters considered include cumulative average value of operculum movement and tail beat frequency, and cumulative number of discoloration, erratic swimming, and mortality for each set of concentrations of the test substance: dispersant, condensate, and oil based mud respectively. The results show that the lethal effect of the substances on the fishes depends on concentration and duration of exposure, as observed that the cumulative average number of discoloration, erratic swimming, and mortality increases with increasing concentration and exposure time, while the cumulative average of operculum movement and tail beat frequency decreases with increasing concentration and exposure time.          Keywords: X(Biosolve), Y(Condensate), Z(Diesel Oil Based Mud).