Dose-Time Effect of Crude Oil and Hydro-test Effluent on Freshwater and Brackish Water Habitats

Abstract

This work was undertaken to investigate the dose-time effect of crude oil and hydro-test effluent on freshwater and brackish water habitats. The species used for the acute toxicity were freshwater fish, Tilapia guineenis (fry) and a brackish water shrimp, Palaemonetes africanus. Test results indicated that the brackish water juvenile shrimps were more sensitive to the mixture of the hydro-test effluent and crude oil than the freshwater habitat. This could be attributed to the physicochemical constituents of the receiving environment. In both the freshwater and brackish water habitats, the higher the concentration and longer the exposure of the test species, the higher the mortality rate. This was evidenced from test result which showed 0% mortality for 100mg/l at 4hrs for both the fresh water and brackish water species respectively, and 100% mortality at 4hrs for 100,000 mg/l concentration of the hydro-test effluent and crude oil mixture. The project therefore has provided a learning tool and a platform inevaluating the concentrations of the chemical and the duration of exposure required to produce the criterion effect. Moreover, test results validated the age long theory that ‘the most important factor that determines the effect of any substance is the dose-time relationship