GENOTOXIC EVALUATION OF ANAMBRA RIVER USING BIOMARKER
ABSTRACT
Genotoxicity of freshwater fish in Anambra River was studied by micronucleus (MN) assay, and the resultant micronucleus indices were used as biomarkers to estimate and predict pollution profile and possible danger of feeding on the aquatic species. The micronucleus profiles of the fish were measured from gill and kidney erythrocytes using microscopic technique. Season, breed, and location effects on micronucleus indices, together with their interactions, and the correlation between the pollutants in fish, water ecosystem, and the micronucleus profiles were also studied. Two major seasons (Rainy and Dry) and preponderant fish breeds in the river [Synodontis clarias -Linnaeus, 1758 and Tilapia nilotica -Linnaeus, 1757] were studied at five distinct locations that displayed differential environmental stresses. The study revealed that the micronucleus index of fish is an excellent biomarker for measuring the level of pollution in a freshwater habitat. This is more evident with regard to zinc and copper. Season, breed and location affect micronucleus profile adversely and strong correlations exist between zinc and copper in water and fish and micronuclei profiles. Disease outbreak among rural dwellers depending on the water for domestic and other uses is imminent and they lack knowledge on its health implication. Furthermore, the study maintained that the micronucleus in fish could be measured with higher efficiency from the gill than the kidney erythrocytes and Synodontis clarias is more vulnerable to genetic damage due to high zinc and copper pollutants than Tilapia nilotica. Consequently, the study recommends environmental sensitization of the resident population and regular monitoring (micronucleus tests) of edible aquatic life such as Synodontis clarias (catfish) in order to eliminate the danger of people feeding on toxic metals, some of which are carcinogenic.