Impact Assessment of Sewage Effluent on Freshwater Crucian Carp Carassius auratus using Biochemical and Histopathological Biomarkers

Abstract

The aim of this study was to assess the influence of effluent discharge from a sewage treatment plant by evaluating oxidative stress and histopathological alterations in freshwater crucian carp Carassius auratus collected from Eungcheon stream, Korea. Catalase activity in the gills, liver, and kidneys of C. auratus collected from the mixing zone and downstream site was notably higher than that in of fish from the upstream site. In addition, the activity of glutathione-S-transferase in the gills and liver was significantly higher in samples from the mixing zone than in those from the upstream site (p < 0.05), and significantly elevated lipid peroxidation levels were observed in fish livers sampled from the mixing zone than in those from the upstream site (p < 0.05). Significant histopathological alternations were also observed in C. auratus, with the order of magnitude of changes being liver > kidney > gills. These findings suggest that the liver is most affected by effluent discharge. The degree of tissue changes (DTC) indicated that the highest level was occurred in samples from the mixing zone (30.98 ± 5.40) followed by those from the downstream site (19.28 ± 4.31), and was the lowest in samples from the upstream site (4.83 ± 2.67). These findings indicate that fish collected from the mixing zone are most affected by effluent discharge and both oxidative stress and histopathological indices are useful tools for monitoring contaminated rivers and streams.