INFLUENCE OF CRUDE OIL EXPOSURE AND RECOVERY ON GROWTH PERFORMANCE OF Oreochromis niloticus

Abstract

Water-soluble fractions (WSF) play a crucial role in the toxicity of crude oil to aquatic organisms. In this study, the effects of water-soluble fractions of crude oil exposure and recovery on growth performance were evaluated in Oreochromis niloticus. Fish (8.6 ± 0.5 g) were exposed to 4 sublethal concentrations (30, 45, 60, and 75% of the LC50 corresponding to 28, 41, 55, and 69 mg/l respectively) of the oil and control. After 90 days of exposure, growth parameters were measured. Previously exposed fish were transferred into other aquaria containing dechlorinated water and left to recover for 90 days. After the recovery phase, growth parameters were also measured. The result showed that the mean weight gained in fish in the test solutions reduced significantly (p<0.05) with increasing concentration. The condition factor of the fish reduced significantly from 1.30 ± 0.10 in control to 0.99 ± 0.18 in the highest concentration of the oil. During the post-exposure (recovery) phase, control groups performed better in terms of growth as the removal of the toxicant did not compensate for the disparity observed during the exposure phase. Thus, the suppression of growth observed in O. niloticus during crude oil exposure and recovery can be used as a biomarker for evaluating the long term impacts of crude oil spillage.