Biomonitoring Metal Pollution in a Reservoir and River in Brazil Using Bullfrog Tadpoles' Tissues and Biomarkers.

Bullfrog tadpoles were exposed (96 h) to water from two sites (the Ibiúna and the Itupararanga reservoir) on the Sorocaba River (São Paulo, Brazil). Metal concentrations (Ba, Cu, Mn, Sr and Zn) and metallothioneins (MTs) levels were determined in the gills (n = 27) and caudal muscle (n = 18). Metals increased in the gills of the animals exposed to the waters of the Sorocaba River in relation to the control and in relation to the animals exposed to the waters of the Ibiúna point. The levels of MT in gills were higher in animals exposed to the Itupararanga reservoir compared to the control. There was a strong correlation between metals and the presence of MT in gills, indicating that this organ can be used in environmental biomonitoring. The results demonstrate the need to protect the waters of the Sorocaba River, and especially the Itupararanga reservoir, through quality monitoring and reduction of anthropogenic pressure.