Evaluation of environmental impacts associated with the rupture of the Fundão dam (Mariana, MG) in amphibians: acute, chronic and behavioral effects

Abstract

Despite economically important, mining sector is responsible for several impacts related to its process and also those linked to the risks of environmental disasters. The breaching of the Fundão dam, located in Mariana-MG resulted in the spillage of 62 million m³ of mining tailings in the water bodies, affecting the biota and the supply of cities along the Rio Doce basin. Although the number of studies evaluating the impacts of the disaster has increased in recent years, the information provided so far is still insufficient to assess the real risks involved, especially considering more vulnerable groups, such as amphibians. Amphibians are currently one of the main threatened extinction groups and habitat contamination has been pointed out as one of the main factors contributing to the decline of several amphibians species. Considering the need of a better understanding of the damage magnitude caused on biota, as well as information and forecasts of future impacts, this research intends to simulate the disaster conditions in a laboratorial scale, evaluating the effects on amphibians. To this end, tadpoles will be exposed to different volumetric proportions of the reject from the rupture of the Fundão dam. During acute exposure, mortality will be assessed over 96 hours. For chronic test, tadpoles will be exposed to the reject during 28 days and the effects on body mass gain, growth, development, abnormalities, and swimming performance will be assessed. The ability to detect a contaminated environment and migration of tadpoles will also be evaluated through the behavioral avoidance test. The accomplishment of these ecotoxicological tests in addition to physical-chemical analyzes will help to clarify how exposure to mining tailings should affect amphibian populations and how this may affect long-term ecosystem dynamics. (AU)