HAEMATOLOGICAL AND SERUM BIOCHEMICAL CHANGES IN Clarias gariepinus EXPOSED TO SUB-LETHAL CONCENTRATIONS OF WATER SOLUBLE FRACTIONS OF CRUDE OIL

Abstract

The exploitation of crude oil resource in Nigeria has resulted in the continuous exposure of fish to crude oil and its refined products. In this study, alterations in haematological and biochemical parameters were evaluated after exposure of Clarias gariepinus to water soluble fraction of crude oil. The 96 h-LC50 of crude oil determined by probit regression was 224.74 mg/l. Fish were exposed to 4 sublethal concentrations (30, 45, 60 and 75% of the LC50 corresponding to 67, 101, 135 and 169 mg/l respectively) of the oil and a control. After 90 days of exposure, blood was collected and used for haematological and biochemical
analyses. Results showed a significant (P<0.05) reduction in the number of red blood cells, and values of packed cell volume and haemoglobin with no definite trend in the values of computed haematological indices. Glucose content (mg/dl) increased significantly (P<0.05) from 289.00 in control to 384.67 in the highest concentration (33% increase) indicating the occurrence of gluconeogenesis to supplement additional energy needed to meet the increased metabolic demands. A significant (P<0.05) inverse relationship between the concentration of crude oil and values of total protein, albumin and globulin was also observed. The mean plasma alanine aminotransferase, alkaline phosphatase, aspartate aminotranferase, creatinine and urea activities of all fish, which have been exposed to sub-lethal concentrations of crude oil were significantly higher (P<0.05) in comparison with
their respective control. The upsurge in the activity of these enzymes is a direct reflection of alterations in the hepatic structural integrity and kidney disorder