HAEMATOLOGICAL AND HEPATIC RESPONSES OF CLARIAS GARIEPINUS TO SUBLETHAL EXPOSURE OF INDUSTRIAL EFFLUENTS FROM OLOGE LAGOON, LAGOS, NIGERIA

Fish in rivers/lagoons receiving high discharges of effluent from industries has shown a range of alterations related to physiological abnormalities. These effects have been attributed to various estrogenic chemicals known to be present within treated or/and untreated industrial effluents. This report is aimed at assessing sub-lethal effects of the effluents on the haematological characteristics and on the tissues of liver using histological techniques on the early life stages of C. gariepinus.

The present study is on the haematological and hepatic responses of Clarias gariepinus to sublethal toxicity of industrial effluents (IE) from the environment of Ologe Lagoon, Lagos, Nigeria. The fish were cultured in five concentrations of industrial effluents: 0% (control), 5%, 15%, 25%, and 35%. Trials were carried out in triplicates for twelve (12) weeks.   Haematological parameters wer: Packed Cell Volume (PCV), Red blood cells (RBC), White Blood Cell (WBC), Neutrophil and Lymphocytes etc; and histological alterations were measured after 12 weeks. Haematological results showed that C. gariepinus had PCV ranging from 13.0±1.7 - 27.7±0.6, RBC ranged from 4.7±0.6 - 9.1±0.1, and Neutrophil ranged from 26.7±4.6 - 61.0±1.0 amongst others. The highest values of these parameters were obtained in the control and lowest at 35%. Reverse effects were observed for WBC and lymphocytes. The liver shows normal liver cells in the control (0%), but at higher toxic levels, there were: vacoulation, destruction of the hepatic parenchyma, tissue becoming eosinophilic and severe disruption of the hepatic cord architecture. The study revealed that disposal of effluents into aquatic environment affects the health of fishes by impairing normal hepatic functions and hinder vital physiological processes if exposure continues for a long period of time.