Tainting and weight changes in Tilapia guineensis exposed to sublethal doses of crude oil

Abstract

The acute toxicity level of the Forcados light crude oil when tested against T. guineensis was found to be 0.4ml/l, based on the 96hr LC50 value. In addition, the toxicity of the crude oil against the test animals, T. guineensis was found to increase with time of exposure. Exposure of T. guineensis to sublethal concentrations (ranging from 0.4μl/l, 4μl/l and 40μl/l) of Forcados light crude resulted in the tainting of the flesh of the test animals. With regards to weight changes, the tested sublethal concentrations of crude oil was found to cause a slight increment in the weight of exposed animals contrary to observations for animals in control media, where a loss in weight was observed. The significance of these observations on sublethal effects of crude oil on aquatic animals is the effect they would have on the setting of safe limits of crude oil in our environment. The mechanism(s) responsible for the weight gain in animals exposed to sublethal concentrations of crude oil should also be investigated.
Key Words: Forcados light crude oil; Oil spillage; Tilapia; Environmental pollution.