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

Abstract

The iron ore tailings resulting from the rupture of the Fundão 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 Espírito 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.