Toxicity of bitumen on Tilapia guineensis from Nigerian Institute for Oceanography and Marine Research (NIOMR), Buguma, Rivers State

This study evaluated the toxicity of bitumen on apparently health T. guineensis (condition factor of 1.976) over a period (24 hrs, 48 hrs. 72 hrs and 96 hrs) using standard analytical procedures. The density, API and flash point of the bitumen used in this study at 15oC was 0.9898 g/cm3, API at 60oF value of 11.46 and >200oC respectively. The total TPH and PAH constituent of the bitumen was 20,549.77 mg/l and 924.09 mg/l respectively. Analysis of the effect of different concentrations (10mg/L, ₂₀ mg/L, ₃₀ mg/L, ₄₀ mg/L and ₅₀ mg/L) of bitumen on T. guineensis revealed that the mortality of the organism increased as the concentration of the toxicant and time of exposure increased. The concentration with the longest exposure time where lowest mortality was observed was 40mg/l for 24 hours. The probit analysis on the lethal concentration (LC₁₀, LC₂₀ and LC₅₀) of the toxicant on T. guineensis when exposed for 96 hours revealed a varying mortality status. The LC₁₀, LC₂₀ and LC₅₀ of the bitumen on the T. guineensis was 6.746 mg/L, 10.773 mg/L and 26.38 mg/L respectively. Continuous discharge of untreated wastes especially petroleum-based products should be discouraged as it poses serious threat to aquatic habitat and produces.