Bioaccumulation of heavy metals in benthic and nektonic tadpoles inhabiting impacted areas after the tailings dam rupture in Mariana, MG, Brazil

The harmful effects of chemical contamination of the environment have motivated the search for tools for the assessment of environmental quality, including bioindicators. Here we evaluate the bioaccumulative potential of benthic and nektonic tadpoles occurring in areas affected by iron ore tailings. We analyzed the concentrations of Al, Ba, Cd, Cr, Cu, 34 Fe, Mn, Ni, Pb, Ti, V and Zn in the water, sediment, and in benthic tadpoles with intestine (BI) and surgically removed intestine (BR), and nektonic tadpoles with intestine (NI) and 36 removed intestine (NR). We collected tadpoles in seven sites directly affected by the tailings and in seven sites without direct contact with the tailings mud. There were no differences in concentrations of heavy metals between the sampling points for water and sediment. Benthic tadpoles (BI) from sites directly affected by the tailings showed higher concentrations of metals Al, Ba, Fe, Mn and Ti, than nektonic tadpoles (NI). On the other hand, NR showed higher concentrations of Cr, Al, Ni, Mn, Zn, Cu and Ti than BR. The highest concentration of metals BI may be linked to the association of the group with the metals adsorbed to the sediment, where there were the highest concentrations. The metals associated with NR are due to accumulation in different tissues of the body. In general, the concentrations of metals in the environment are reflected in the tadpoles’ tissues. Additionally, the differences between benthic and nektonic tadpoles show the movement of these metals along the trophic chain in this ecosystem.