Devastating Rio Doce mining disaster sends shockwaves through earthworm populations.

Abstract

The Fundão dam breach is considered one of the most severe environmental mining disasters globally, causing widespread changes to the soils of the Rio Doce watershed, one of Brazil's most important catchments. Given the ecological importance of earthworms to soil structure and dynamics, we investigated the richness, abundance, and biomass of both native and invasive earthworm species in riparian zones along the Rio Doce to understand their responses to the altered soil conditions. Sampling was conducted in reference and impacted sites across five municipalities in Minas Gerais: Mariana, Rio Casca, Ipatinga, Conselheiro Pena, and Aimorés. We identified eight species-two invasive (Amynthas gracilis and Pontoscolex corethrurus) and six native (two Rhinodrilus, three Righiodrilus, including at least two undescribed species, and one Ocnerodrilidae species)-with native biomass approximately five times lower in impacted sites compared to reference sites. Furthermore, the new tailings environment altered the relationships between soil properties and earthworm abundance for both native and invasive species. These findings indicate that native earthworms are less tolerant of the disturbed soil conditions than invasive species, which may contribute to shifts in community composition. The disruption of soil-fauna interactions underscores the long-term ecological consequences of mining-related disturbances and highlights the need for restoration efforts that consider belowground biodiversity.