Heliyon (Aug 2020)

Adaption of microbial communities to the hostile environment in the Doce River after the collapse of two iron ore tailing dams

  • Adriana Giongo,
  • Luiz Gustavo dos Anjos Borges,
  • Letícia Marconatto,
  • Pâmela de Lara Palhano,
  • Maria Pilar Serbent,
  • Eduardo Moreira-Silva,
  • Tiago de Abreu Siqueira,
  • Caroline Thais Martinho,
  • Rosalia Barili,
  • Lisiê Valéria Paz,
  • Letícia Isabela Moser,
  • Carolina De Marco Veríssimo,
  • João Marcelo Medina Ketzer,
  • Renata Medina-Silva

Journal volume & issue
Vol. 6, no. 8
p. e04778

Abstract

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In November 2015, two iron ore tailing dams collapsed in the city of Mariana, Brazil. The dams' collapse generated a wave of approximately 50 million m3 of a mixture of mining waste and water. It was a major environmental tragedy in Brazilian history, which damaged rivers, and cities 660 km away in the Doce River basin until it reached the ocean coast. Shortly after the incident, several reports informed that the concentration of metals in the water was above acceptable legal limits under Brazilian laws. Here the microbial communities in samples of water, mud, foam, and rhizosphere of Eichhornia from Doce River were analyzed for 16S and 18S rRNA-based amplicon sequencing, along with microbial isolation, chemical and mineralogical analyses. Samples were collected one month and thirteen months after the collapse. Prokaryotic communities from mud shifted drastically over time (33% Bray-Curtis similarity), while water samples were more similar (63% Bray-Curtis similarity) in the same period. After 12 months, mud samples remained with high levels of heavy metals and a reduction in the diversity of microeukaryotes was detected. Amoebozoans increased in mud samples, reaching 49% of microeukaryote abundance, with Discosea and Lobosa groups being the most abundant. The microbial communities’ structure in mud samples changed adapting to the new environment condition. The characterization of microbial communities and metal-tolerant organisms from such impacted environments is essential for understanding the ecological consequences of massive anthropogenic impacts and strategies for the restoration of contaminated sites such as the Doce River.

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