Haematological Response of African Catfish (Clarias gariepinus) and Rat to Crude Oil Exposure

The effect of Bonny light crude oil on some haematological parameters was studied in African catfish (Clarias gariepinus) and rats. A total of 120 catfish were grouped into 6 of 20 catfish each and held for 30 hours in 5 different mixtures of crude oil polluted water (0.1%, 0.25%, 0.5%, 0.75% and 1% v/v). Catfish in the control group were held in borehole water. At the expiration of 30 hours, the catfish were harvested and used to formulate diet. Albino rats (n = 60) were grouped into 6 of 10 rats each and fed on the formulated diet for a period of 30 days. The control rats were fed on diet containing catfish cultured in borehole water while those in groups 2 to 6 were fed on diets containing catfish exposed to the various mixtures of crude oil. The red blood cell (RBC) count reduced significantly (p<0.05) as the concentration of crude oil increased in both the catfish and rat indicating an anaemic condition. The decrease also affected dependable factors such as packed cell volume (PVC), haemoglobin (HGB), platelet (PLT), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC). Furthermore, white blood cells (WBC), the main defense cells of the animals decreased significantly (p<0.05) further indicating susceptibility to stress and infection. Overall, the results indicate that exposure to crude oil has serious consequences on haematological parameters of catfish and rat which may be attributed to the toxic components of crude oil.