Impact of iron ore mining on benthic macroinvertebrate community

Résumé

Anthropogenic disturbances may negatively affect the quality of freshwater ecosystems. Among these disturbances, metal mining has increased at an alarming rate, often impacting small water bodies and thus aquatic communities. Therefore, the aim of this study was to test the hypothesis that the residuals of iron ore mining may decrease the species diversity of a benthic macroinvertebrate community in a stream. For this, three streams were evaluated in a mining area, and in each one samples of the macroinvertebrates were taken and a record of the abiotic factors made. It was found that taxa diversity in impacted streams is much lower than in preserved streams. Furthermore, the fauna composition in impacted streams was restricted to groups extremely resistant to environmental disturbances, such as Chironomus and Pseudosmittia. Changes in the physicochemical parameters of water, such as acidification and a decrease in dissolved oxygen, were also observed. This is one of the few studies in Brazil that demonstrates that the residuals of iron ore mining may decrease the diversity and modify the composition of the benthic macroinvertebrate community, contributing to future studies about the conservation of aquatic ecosystems.