Seasonality effects on the metal concentration and biochemical changes in Astyanax lacustris (Teleostei: Characiformes) from Doce River after the collapse of the Fundão dam in Mariana, Brazil.

This study aimed to evaluate the harmful effects of metal accumulation on Astyanax lacustris and their biochemical response when exposed to the metals contained in the Doce River water, Brazil. The study was carried out in the Baixo Guandu region of the Doce River, Espírito Santo state. Samples were collected during the dry and wet seasons. Biochemical alterations were observed in the liver of A. lacustris, with apparent seasonal effects directly related to the high concentration of Al and Fe in this tissue. Despite this, the bioconcentration of metals in the organisms showed seasonal effects only in the gills, as they are the first organ in contact with the contaminated water. The data generated in this study provide an overview of the health of the ecosystem in this region, highlighting the harmful biochemical and metal concentration effects on the population of A. lacustris affected by the Fundão dam failure.

Do Manganese and Iron in Association Cause Biochemical and Genotoxic Changes in Oreochromis Niloticus (Teleostei: Cichlidae)?

The present study aimed to evaluate the toxicity of the association between Fe and Mn in Oreochromis niloticus through genotoxic (micronucleus test and comet assay) and biochemical (CAT and GST enzymes) assays. The tested treatments were T1 = control group (without metal addition), T2 = 2.60 mg L-1 of Fe + 0.2 mg L-1 of Mn, and T3 = 4.40 mg L-1 of Fe + 3.49 mg L-1 of Mn, during 96-h bioassays. All animals exposed to the metals showed a significant increase in erythrocyte micronucleus frequency and DNA damage. The hepatic GST activity increased two times in animals exposed to T3 compared to the control group. The results indicate that Fe + Mn caused genotoxic and biochemical changes in exposed fish. Therefore, excess metals in ecosystems, even those essential for organisms, can be dangerous for the local biota due to the risk associated with high concentrations of these metals.