Cytogenetics of Chrysichthys nigrodigitatus as Bioindicator of Environmental Pollution from Two Polluted Lagoons, South-Western Nigeria

Pollution of aquatic ecosystems from anthropogenic activities has heightened in recent times and this has elicited national and international concern on the impacts on aquatic biota. This study investigated the genotoxic effects in C. nigrodigitatus from two polluted lagoons. Micronuclei (MN) test, as an index of chromosomal damage, is widely applied in field studies. The peripheral erythrocytes from C. nigrodigitatus were subjected to MN analysis and physicochemical parameters were evaluated following APHA standardized protocol. There were significant (p < 0.05) seasonal variations in water temperature, pH, dissolved oxygen (DO) and biochemical oxygen demand (BOD5) across sampling stations in both lagoons. The levels of DO and BOD5 were below permissible limits (FMEnv) in both lagoons. Cytogenetic analyses revealed a statistically significant (p < 0.05) in MN frequencies with 70.2% and 29.8%, while the nuclear abnormalities (NAs) observed an increased formation of 68.7% Binucleated cells (BN) and 31.3% BN; 60% of blebbed cells (BL) and 40% BL; 58.8% lobed cell (LB) and 41.2% LB in Ologe and Badagry lagoons respectively. MN and NAs induction increased in the order of frequencies; MN > BN > BL > LB in the peripheral erythrocyte of catfish from both lagoons. Pearson correlation showed negative significant induction (p < 0.05) with the frequencies of MN and BN induced by BOD and Conductivity in both lagoons. The induction of MN formation and nuclear abnormalities (NAs) in catfish are sensitive non-specific indicators for mutagenic damage, exposed to admixtures of chemical and organic compounds from Ologe and Badagry lagoons. Thus, micronucleus assay serves as a good biomarker for biomonitoring aquatic ecosystems.