Comparative effects of crude oil on juveniles Clarias gariepinus and Clarias anguillaris

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. gariepinus compare to
C. anguillaris that tend to elicit a low tolerance to the crude oil.