Genotoxicity risk assessment in fish (Rutilus rutilus) from two contaminated rivers in the Kosovo

Being exposed to untreated urban and industrial water, the rivers Drenica and Sitnica are considered to be the most polluted ones in the Kosovo. Our previous investigations on the cyto- and genotoxic potential of water samples from these rivers evaluated with primary rat hepatocyte cultures indicated a risk for the health of aquatic organisms. In order to assess the genotoxic risk to aquatic organisms, we therefore performed a two year study (2016-2017) on roach (Rutilus rutilus) from these rivers. Specimens were collected at three locations along the Drenica river and two locations along the Sitnica river, and the genotoxicity was evaluated by the micronucleus as well as the Comet assay (DNA damage) in erythrocytes. The frequencies of micronucleated cells were determined for samples collected in four seasons, whereas the Comet assay was employed on samples collected in five seasons during the two-year period. The data obtained revealed an increase of the frequency of micronucleated erythrocytes from Rutilus rutilus collected at most sampling locations and from both rivers at all seasons investigated. Significant differences to the control (lake Badovc) were found in summer 2016 and spring 2017 samples. When comparing the seasons, the summer 2016 samples were most genotoxic, followed by spring 2017 and autumn 2016. With regard to the Comet assay data, a similar but more prominent "response" was observed. Another important observation is that micronucleus rates as well as DNA damage levels were significantly higher in samples collected in 2016 compared to the respective seasons in 2017. Altogether, the "response" obtained with both markers confirmed a genotoxic risk for fish due the pollution of these rivers. Since there were, however, seasonal and annual variations of the genotoxicity levels further in depth studies have to be carried out addressing the nature of these changes.