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Biomarker profile of a silver catfish Chrysicthys Nigrodigitatus in heavy metal polluted areas of the Lagos Lagoon, Nigeria

Aquatic ecosystems are usually exposed to contaminants including heavy metals from anthropogenic activities and high concentration of these metals may alter physiological function in fish muscle. Assessment of biomarker profile will provide the role of antioxidant defence enzymes in response to metal accumulation. The present study aims to find the relationship between biomarker pattern in fish muscle and the contribution of antioxidant defence enzymes to sustain balance from metal toxicity. Adult fish (Chrysicthys nigrodigitatus), water and sediment samples were taken from five sampling stations, during the wet and dry season in the Lagos Lagoon. Heavy metals (lead, cadmium, chromium, copper, zinc, iron) levels, antioxidant defence enzyme activity (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione) and malondialdehyde were analysed in fish muscle using standards methods. Heavy metal levels showed significant difference (p<0.05) in fish muscles, water and sediment, with values above recommended standard for aquatic life. PCA showed that elevated activities of antioxidant defence enzymes correlated with increase metal concentrations within the fish muscle, which may indicate possible oxidative stress. Hence, measures should be implemented and sustained in the treatment of effluents before discharging into the aquatic habitat so as to reduce stress and sustained the wild population.