Determination of oxidative, genotoxic, and histopathologic effects of metal pollution on the fish fauna inhabiting Karasu River, Turkey

Abstract

The water quality of rivers located in areas close to major cities is deteriorating significantly due to increased pollution. The Karasu River, which passes through Erzurum city Turkey, is getting polluted day by day due to domestic and industrial wastewater. In the study, various assessments were made in three different fish species to determine the impact of possible contamination here. Capoeta capoeta, Alburnus mossulensis and Squalius cephalus were caught from four stations of the river. Micronucleus test was applied to find out genotoxic alterations, and plasma total oxidant status (TOS) and total antioxidant status (TAS) were measured to determine oxidative effects. Histological changes in fish brain were also assessed by histopathological alterations index (HAI). The highest serum TOS levels and the lowest TAS levels were detected in fish species inhabiting polluted stations. A high erythrocytic nuclear abnormality frequency and HAI values were observed in all species from the Aşkale stations. The abnormalities observed in the peripheral blood cells were micronucleus, binucleus, kidney-shaped nucleus, notched nucleus, lobed nucleus and bud nucleus. Histological damages like dilatation, congestion, vacuolization in Purkinje layer, infiltration, hyperemia, degenerations, and axonopathy were noticed in all fish brains. It was determined that histopathological changes were more common in fish species inhabiting the polluted stations. S. cephalus showed to be more sensitive to the pollution. The most important result obtained from this study is that the pollution in the river adversely affects the fish species found in the natural fauna of the river. Histopathological abnormalities, genotoxicity and increased oxidative stress detected in fish are the most important indicators of this situation.