Genotoxic effects of urban pollution in the Iguacu River on two fish populations

Environmental impacts on water resources and discharges of pollutants are some of the main problems of aquatic ecosystems. Currently, the Iguacu River is considered the second most polluted river in Brazil, therefore, given the importance of understanding the effects of water pollution on living organisms, this study aimed to analyze the possible genotoxic effects in Astyanax bifasciatus (Characiformes; Characidae) and Geophagus brasiliensis (Perciformes: Cichlidae) in response to the water quality of the Iguacu River. Four sampling points were determined on the Iguacu River, with different levels of environmental impact. The micronuclei and nuclear abnormalities were quantified by counting 2000 erythrocytes from each specimen. There was a statistical difference in the frequency of nuclear abnormalities both for A. bifasciatus (Kruskal-Wallis (3;30) = 10.9; p = 0.01) and for G. brasiliensis (Kruskal-Wallis (3;26) = 12.27; p = 0.006), with point 1 (critically degraded) showing a higher frequency of nuclear abnormalities and point 4 (moderately degraded) showing a lower frequency of nuclear abnormalities for both species, showing genotoxic potential in fish erythrocytes. This result demonstrates the need for further discussion on the conservation of the Iguacu River as well as broadening the discussion on its potability.