Abstract

This study was based on biochemical assessment of the effect of crude oil spillage on marine life. Hence, life sustaining indices such as pH, dissolved oxygen (DO), and free CO₂ were analyzed in aquaria. However, a 96 h static acute toxicity test was also investigated on the juveniles Clarias gariepinus (African catfish) and Clarias anguillaris(mudfish) on exposure to different concentrations of crude oil polluted water. Over the period of the experiment there was an overall decrease in pH of the test vessel from 8.64 ± 0.03 to 5.50 ± 0.08. Decrease trend was also found in dissolved oxygen from 6.28 ± 0.07 to 3.01 ± 0.06 and free CO₂ levels from 8.35 ± 0.55 to 11.25 ± 0.17. However as the concentration of crude oil increases the haematological parameters such as red blood cell (RBC), packed cell volume (PCV), and white blood cell (WBC) reduced significantly (p ≤ 0.05) in both fish species. After 96 h, probit analysis showed the LC₅₀ of crude oil for C. anguillaris to be 1.22 mg/L while that of C. garieinus was 2.19 mg/L. Overall, less insults was observed from the crude oil on C. gariepinuscompare to C. anguillaris that tend to elicit a low tolerance to the crude oil.

Key words: Clarias gariepinus, Clarias anguillaris, crude-oil, LC₅₀, and static-acute.