Evidence of reproductive disturbance in Astyanax lacustris (Teleostei: Characiformes) from the Doce River after the collapse of the Fundão Dam in Mariana, Brazil.

The Fundão Dam collapsed, on November 5th, 2015, dumping more than 50 million/m of iron ore tailings, enriched with metals, into the Doce River channel. The objective of this study was to evaluate the reproductive biology and histological damage in Astyanax lacustris specimens exposed to the metals from the dam collapse. The study was carried out at Doce River, in Espírito Santo State, Brazil. Monthly samplings were carried out for a year. Astyanax lacustris had multiple spawning: females' reproductive peak was in September, October, November, and December; and males between September, October, January, and February. There was a latency in the formation of gonads. For male gonads, it was necessary a 6 cm growth for it to increase from 30 to 50% and 4 cm for female gonads to increase from 40 to 50%. There is a positive correlation between gonad's concentration of Al and Fe and the rate of histological damage in females. Male gonads had a high rate of immature cells invading the cell lumen (47.36%) and female gonads showed a higher frequency of atresia (39.64%). Fish exposed to the contaminated water showed moderate-high gonad histological damage. The observed changes can directly influence the organism's development and reproduction in the long run, thus affecting A. lacustris population present in the region.