Metal concentrations, oxidative status and histopathological evaluation of fish species from Doce River, Brazil, after the Fundao dam collapse

Eight years after the tailings dam collapse in Mariana, MG, Brazil, several aspects of this massive disaster are yet to be elucidated. Our goal was to investigate the impact of the mud flow on 16 fish species collected across 15 points from the Doce River, addressing 12 metal concentrations, tissue oxidative status (antioxidant enzymes and stress biomarkers), and histopathological analyses. The species Trachelyopterus striatulus, Prochilodus vimboides, Loricariichthys castaneus, Lophiosilurus alexandri, Hypostomus affinis, Hoplias intermedius were shown to be the most affected regarding the gills tissue integrity; Hypostomus affinis, Oligosarcus acutirostris, Lophiosilurus alexandri, Pygocentrus nattereri, Hoplosternum littorale, and Loricariichthys castaneus showed the highest levels of liver health. Overall, H. affinis was the most affected species, showing high levels of oxidative and histopathological damage, associated with high arsenic (As) and mercury (Hg) concentrations. In fish sampled from impacted regions, As and Hg exhibited higher concentrations compared to fish from unaffected sites, surpassing all the other analyzed metals. These high metal concentrations might be associated to the tailings dam failure, and As and Hg concentrations were positively correlated with alterations in oxidative stress biomarkers and histopathologies. Our results may be used as baseline for monitoring the environmental challenges that the Doce River fish species are facing at the moment.