EFFECTS OF MUNICIPAL EFFLUENT ON TISSUE INTEGRITY:

A HISTOPATHOLOGICAL STUDY OF Clarias gariepinus FROM AKOKA

Abstract

This study investigates the impact of municipal effluent from Akoka runoff comprising household wastewater and precipitation on the health of Clarias gariepinus. The primary objectives were to quantify heavy metal concentrations in Akoka runoff, evaluate their toxic effects on C. gariepinus, and conduct histopathological analyses of exposed specimens. Both acute and sub-lethal biochemical responses were assessed, with particular focus on heavy metal toxicity resulting from
exposure to municipal effluent and potassium chloride (KCl). Probit analysis was employed to determine 96-hour median lethal concentrations (LC₅₀), alongside sub-lethal effects monitored
over a 14-day exposure period. Results showed that the LC₅₀ of the municipal effluent was 0.9218, while that of KCl was 0.799. Statistical analyses using one-way ANOVA (p < 0.05) in SPSS Version 20.0 indicated no significant differences between mortality data from replicate tests,
affirming the consistency of the results. The LC₅₀ represents the concentration at which 50% of test organisms perish, with 95% confidence intervals derived through linear regression of logtransformed
data. Heavy metal analysis revealed that only lead (Pb), at 0.01 mg/L, met World Health Organization (WHO) permissible limits. Manganese (Mn) and cadmium (Cd) exceeded these regulatory thresholds. The findings underscore the urgent need for effective monitoring and remediation of municipal runoff to protect aquatic organisms and maintain environmental integrity.