Genotoxicity effects on Geophagus brasiliensis fish exposed to Doce River water after the environmental disaster in the city of Mariana, MG, Brazil

Abstract

The Doce River basin has suffered the largest environmental accident ever occurred in Brazil with the influx of tailings from Fundão and Santarém, belonging to Samarco mining company, due to the disaster in Mariana. A spill between 50 and 60 million m3 of tailings was estimated by the company. According to Samarco, the wastewater was composed mainly of clay, silt and heavy metals like iron, copper and manganese. Thereby, the objective of the present study was evaluated the genotoxic damage in juvenile of Geophagus brasiliensis (Quoy e Gaimard, 1824) exposed to Doce river water before (DRWBA – Doce River water before acident) and after (DRWAA – Doce River water after acident) the influx of tailings from the Germano and Santarém Dam disasters in Mariana, MG, Brazil. For this, 24 individuals of the species G. brasiliensis (obtained on IFES/ALEGRE fish culture) were submitted to a bioassay with three treatments and eight replicates. The treatments were: 1) Control water (water from the urban water supply system, filtered with a 0.45 µm membrane), 2) DRBA and 3) DRAA. After 96 h, these fishes were anesthetized to remove blood for evaluation of genotoxic damage (micronucleus and comet). For the bioassay, a total of 80 L of The Doce River water were collected before the influx of tailings and after the influx and then submitted to metal quantification analysis. Fish exposed to DRWBA and DRWAA treatments showed a significant increase in both the number of erythrocyte micronuclei and the DNA damage index in relation to the control fish; however, they did not present any differences between the two treatments. The results demonstrate that the DRWBA treatment was already genotoxic for the fish, mainly due to dissolved Cu concentrations in the water. The DRWAA treatment probably presented genotoxicity due to the increase in the dissolved fraction and synergistic effects of several metals found in the tailings of the Mariana accident.

Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015

“…For this reason, the impacts that the Mariana dam disaster may have had on these species, both of which were already threatened with extinction, are acutely concerning. The mudflow resulting from this incident had a high concentration of heavy metals ( Frainer et al 2016 , Marta-Almeida et al 2016 , Miranda and Marques 2016 , Gomes et al 2018 ), and cetaceans are particularly at risk of intoxication due to biomagnification along the food chain ( Fossi and Panti 2018 ). Furthermore, the extent of the mudflow led to substantial impacts to the marine environment which likely also affected prey availability for these species ( Frainer et al 2016 , Miranda and Marques 2016 ).…”

“…Previous studies found that most Guiana dolphins stranded in Brazil are immature males (Lima et al 2017), which is consistent with the sex ratio of 68% males recorded in this study. The species is known to be frequently bycaught in gillnets in Espírito Santo (Barros et al 1997, de Freitas Netto and Barbosa 2003, de Freitas Netto and Di Beneditto 2008, especially before reaching sexual maturity, with 80% of bycaught individuals corresponding to male individuals younger than 6 years (Rosas et al 2003, Di Beneditto andRamos 2004). The finding that stranded individuals were also predominantly young males (at least for the subset of 149 individuals for which sex was determined, bearing in mind that sex was not determined for 57% of Guiana dolphin strandings in this study) suggests that a substantial proportion of the strandings recorded in this study might correspond to individuals that were bycaught in gillnets and then washed ashore.…”

“…The toxic brown mud released by this disaster flowed through the Doce River until reaching the sea at Linhares, Espírito Santo. The toxic effects of the heavy metal-contaminated mudflow became a major concern for the marine fauna along the Espírito Santo coast (Frainer et al 2016, Marta-Almeida et al 2016, Miranda and Marques 2016, Gomes et al 2018. While studies are still under way in order to evaluate the impacts of the Mariana dam disaster on the marine environment of Espírito Santo, this study provides a compilation of the data on cetaceans strandings in the 40 years preceding the disaster, providing a historical baseline for the region.…”

Genotoxic effect of heavy metals on Astyanax lacustris in an urban stream

“…(2018) reported that A. lacustris from impacted sites had higher concentrations of Pb, Cu, Fe, Zn, and Ni in muscle tissue and higher frequency of micronucleus. Geophagus brasiliensis , in a Brazilian River, had an increase of DNA damage associated with Fe, Mn, Cd, Cu, and Pb ( Gomes et al., 2019 ). Ghisi et al.…”

Adaption of microbial communities to the hostile environment in the Doce River after the collapse of two iron ore tailing dams

“…The accident resulted in the deposition of a substantial load of suspended sediments and ore waste along the river basin. The subsequent increase in turbidity and chemical alteration of water caused the death of thousands of fish and other aquatic organisms along the river's 660 km and also affected many marine habitats ( IBAMA, 2015 ; Fernandes et al., 2016 ; Miranda and Marques, 2016 ; Guerra et al., 2017 ; Gomes et al., 2018 ). The mining waste and water also spread over 1,775 ha of land along the river, including 835 ha of environmental protection areas, 236 ha of Atlantic Forest and 88 ha of natural vegetation ( CONAMA, 2005 ; IBAMA, 2015 ; Miranda and Marques, 2016 ; SEDRU, 2016 ; SOS Mata Atlântica and INPE, 2016 ; Carmo et al., 2017 ).…”