Multibiomarker approach in a neotropical fish to evaluate an urbanized river.

Agricultural and urban waste contains various contaminating substances that reach rivers and bodies of water daily. Anthropogenic activities threaten the integrity of aquatic ecosystems and the resident species. Hypostomus ancistroides is a neotropical fish that is part of the South American fauna. Due to their benthic habit and trophic niche, these organisms can be directly exposed to mutagenic pollutants. Therefore, this study aimed to investigate the toxicity of urbanized and rural river waters (Toledo River and Santa Quitéria River, Toledo, Paraná, Brazil) by evaluating the genotoxic and biochemical effects in H. ancistroides. Fish were collected at two urbanized points on the Toledo River (P1, urban; P2, urban and rural-influenced) and at one point on the Santa Quitéria River (P3), located in the rural area of Toledo. The frequency of micronuclei, erythrocyte nuclear abnormalities (ENAs), and biochemical biomarkers (superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and lipid peroxidation) were analyzed across two seasons (summer and winter). Micronuclei and ENAs were observed in H. ancistroides specimens both in urban and rural areas, with the highest occurrence in P2 during the winter. Concerning biochemical biomarkers, H. ancistroides showed a significant increase in SOD during summer in P2 but no significant difference in CAT. Lipid peroxidation during winter in P2 and P3 was higher than in P1 during summer. Higher GST activity was observed in the specimens in P1 and P2 during winter. Both rivers suffer from the impact and contamination caused by human activities, especially during winter. However, the greatest genotoxicity was observed in P2, indicating a high risk of contamination to the aquatic organisms inhabiting the local area.