INDUCTION OF MICRONUCLEI ABNORMALITIES IN WILD POPULATION OF Sarotherodon melanotheron ALONG A CONTAMINATION GRADIENT OF A TROPICAL LAGOON ECOSYSTEM

Abstract

The urgent need for more sensitive indicators in biomonitoring of aquatic pollution prompted the assessment of potential changes in water quality and micronuclei induction in the erythrocytes of Sarotherodon Melanotheron from the Lagos Lagoon using standard methods and procedures. Physicochemical analysis of surface water revealed varying concentrations of measured parameters with relatively higher levels in the dry season. The obtained levels from the evaluation of lagoon surface water quality did not exceed the Nigerian Federal Ministry of Environment limits set for environmental protection and the condition factor of fish used for the study were within optimum range. The results of the micronuclei test revealed possible nuclear alterations as observed by higher ratio of immature erythrocytes. Although there was no significant difference in the observed immature cells, relatively higher mean values for immature cells (219.0 98.31) was recorded in the dry season compared to the wet season (89.33 2.03), suggesting potential haemolytic anaemia during the dry season. Significantly (p < 0.05) higher mean values of micro-nucleated cells (99.67 12.84) were also recorded in erythrocytes of fish during the dry month of May. From the results, the importance of using the micronuclei frequency (MN) and other nuclear abnormalities in socioeconomically important fish species to provide in situ biological indicators of the effects of anthropogenic activities in coastal waters cannot be overemphasized