Toxicogenetic effects on fish species in two sub-basins of the upper Paraguay river, Southern Pantanal - Brazil.

This study aimed to evaluate water quality using limnological parameters in two sub-basins of the Negro and Apa Rivers, along with the composition and structure of the landscape around the locations sampled in the two sub-basins and their possible contribution to the loss of water quality. We also set out to identify the genotoxic effects on the erythrocytes of Prochilodus lineatus and Leporinus friderici. In particular, we quantified total Cr, Ni and Pb in the muscle of these fish species to determine which genotoxic changes are related to the concentration of metals detected in the fish from these two sub-basins of the Paraguay River Basin. The sub-basin of the Apa River presented a greater proportion of surrounding pastureland in relation to the basin of the Negro River. The erythrocytes of P. lineatus showed a significant difference between the sub-basins for nuclear pyknosis, binucleated cells and lobed nuclei (p < 0.05). In L. friderici, vacuolated nuclei, nuclear pyknosis and lobed nuclei alterations also showed a significant difference between the sub-basins (p < 0.05). The genotoxicity index of the Apa River sub-basin presented higher frequencies of nuclear alterations in P. lineatus and L. friderici (p < 0.05), compared to the Negro River sub-basin. The concentration of total Cr, Ni and Pb in the muscles of P. lineatus and L. friderici in the Negro River sub-basin leads to genotoxic damage, mainly from the induction of lobed nuclei. Based on our results, it can be concluded that toxicogenetic effects in native fish species are an important source of environmental diagnosis in the Upper Paraguay River Basin.