An integrated physiological and metabolic approach reveals how Restinga shrub species cope with the iron ore tailing plume along the coastal region of Espírito Santo-Brazil

The iron ore tailings resulting from the rupture of the Funda similar to o dam, in Mariana-MG, Brazil, impacted the Doce River basin affecting the flora and fauna in the region. Plants that grow in contaminated soil exhibited changes in metabolism, and reduced growth and biomass, coupled with phytotoxicity symptoms. However, several species are able to exclude or even accumulate metals through adaptive strategies. Here, we investigated physiological and metabolic responses in Restinga shrub species affected by the mining plume from the contaminated sea. We carried out all analyses in two different shrub species at eight sample Restinga stations along the coastal region of Espirito Santo state, Brazil. Accumulation of metals during the rainy season coupled with higher levels of these metals in sampling stations were observed. Increased stomatal conductance coupled with higher intercellular CO2 concentration were observed during the rainy season which was characterized by high temperatures. Correlations between metals and metabolic responses were evident and our results pointed out the occurrence of acclimation responses such as maintenance of photosynthesis, and accumulation of free amino acids, carbohydrates, and antioxidants. The differential physiological responses found between the two species analyzed here suggest a genetic load capable of responding, at least partially, to stressful conditions associated with the iron ore tailing plume.

Automated summary

The rupture of the Funda similar to o dam in Mariana-MG, Brazil resulted in iron ore tailings that impacted the Doce River basin, affecting the flora and fauna in the region. Plants in contaminated soil showed changes in metabolism, reduced growth and biomass, and phytotoxicity symptoms. However, some species were able to exclude or accumulate metals through adaptive strategies. In this study, we investigated the physiological and metabolic responses in Restinga shrub species affected by the mining plume from the contaminated sea. We found that the rainy season led to the accumulation of metals and higher levels of these metals at the sampling stations. Increased stomatal conductance and intercellular CO2 concentration were observed during the rainy season, which was characterized by high temperatures. The results showed correlations between metals and metabolic responses, indicating acclimation responses such as maintenance of photosynthesis, and accumulation of free amino acids, carbohydrates, and antioxidants. The differential physiological responses between the two species analyzed suggest a genetic load capable of partially responding to stressful conditions associated with the iron ore tailing plume.