Long-term impacts on estuarine benthic assemblages 4.2 years after a mine tailing spill in SE Brazil

The Rio Doce estuary was critically impacted in 2015 by the world largest mining tailing spill, with still unclear long-term effects on the aquatic biota. Here we present a long-term (2015 to 2020) assessment of estuarine benthic assemblages, where we demonstrate that despite a decline in the absolute concentrations of potentially toxic elements; enrichment factors are still above pre-impact conditions in the estuary. The presence of these contaminants are likely responsible for a continued low habitat quality for the benthic fauna, characterized by a reduction of 96% of the macroinvertebrate density and persistent change in the benthic assemblage composition. Our study supports previous work indicating the long-term nature of pollution impacts in estuaries, and demonstrate that although water quality levels were quickly adequate under regulatory terms, they largely lack significance to the overall ecosystem health assessment, as they are not related to the recovery of bottom-dwelling assemblages in estuarine ecosystems. ### Competing Interest Statement The authors have declared no competing interest.