Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv Effects of metal contamination on liver in two fish species from a highly impacted neotropical river: A case study of the Fundão dam, Brazil André Alberto Weber a , Camila Ferreira Sales a , Francisco de Souza Faria a , Rafael Magno Costa Melo a , Nilo Bazzoli b , Elizete Rizzo a,* a Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, C.P.486, 30161-970, Minas Gerais, Brazil b Programa de Pós-graduação em Zoologia de Vertebrados, Pontifícia Universidade Católica de Minas Gerais, PUC Minas, Belo Horizonte, 30535-610, Minas Gerais, Brazil ARTICLE INFO Keywords: Hoplias intermedius Hypostomus affinis Metallothionein Oxidative stress Doce river ABSTRACT Environmental disasters such as the rupturing of mine tailings dams are a major concern worldwide. In the present study, we assess the effects of the release of mine waste due to the rupture of the Fundão dam on two native fish species (Hoplias intermedius and Hypostomus affinis) from the Doce River basin. Two sampling sites were chosen: S1, a reference site, and S2, contaminated by mining waste. Water and sediment were collected to evaluate metals concentration. Adult fish were caught to analyse biological parameters, hepatic histopathology, and biomarkers of metal contamination. Compared to site S1, the concentration of manganese was statistically higher in water while lead, nickel, and arsenic were statistically higher in the sediment from site S2, and iron had no significant difference between sites. At site S1, fish of both species presented hepatic tissue with normal architecture. At site S2, hepatic alterations, such as cytoplasmic vacuolization and necrosis were frequently found in both species. Regarding the histopathological index, higher values were found in both species from site S2. The positive antibody reactions for cytochrome P450 1A (CYP1A) and metallothionein (MT) were statisti- cally greater in site S2 for both species. The oxidative stress biomarkers, superoxide dismutase (SOD) and cat- alase (CAT) were statistically higher in H. intermedius from site S2, but only CAT was statistically greater in H. affinis at site S2. These results demonstrate that the release of mineral residues from the rupture of the Samarco mine dam is provoking hepatic damage in the fish from the Doce River besides inducing the expression of proteins and enzymes related to metal contamination. 1. Introduction The disaster of mine tailings that occurred in the Doce River basin in November 2015, due to the rupture of the Fundão dam owned by Samarco S.A., was one of the largest mining disasters in the world (Cordeiro et al., 2019). It has been estimated that 43–60 million m 3 of mining waste reached Doce River basin, contaminating more than 650 km of rivers until the Atlantic Ocean (Andrade et al., 2018; Segura et al., 2016). Wild fish are continually exposed to different types of contaminants, so they are considered excellent models for assessing health status of aquatic ecosystems (Dane and Sisman, 2015; Paschoalini et al., 2019). Heavy metals may enter in the aquatic environment either naturally (e.g. geological processes) or anthropogenic (e.g. mining). The release of metals to aquatic environments by anthropogenic activities is much higher than those observed by natural processes (AnvariFar et al., 2018). To evaluate the effects of these metals on fish liver, several biomarkers are frequently used including metallothionein (MT), cyto- chrome P450 (CYP1A), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) (Hermenean et al., 2015; Linde-Arias et al., 2008a, 2008b; Rajeshkumar et al., 2013; Rajeshkumar and Li, 2018). The liver is the most important organ in drug metabolism and de- toxification of different environmental contaminants (Bernet et al., 1999). Heavy metals can alter lipid and carbohydrate metabolism by binding or blocking nuclear receptors and can also activate cell death mechanisms, like caspases or some kinases involved with necrosis in liver (AnvariFar et al., 2018). Field studies demonstrate an association between metals contamination with steatosis and necrosis in fish liver (AnvariFar et al., 2018; Hermenean et al., 2015; Rajeshkumar et al., 2013). The exposure of fish to metals promotes the induction of hepatic proteins, including metallothionein (MT) and cytochrome P450 1A (CYP1A) (Almeida et al., 2014). Metallothioneins are small proteins https://doi.org/10.1016/j.ecoenv.2020.110165 Received 9 October 2019; Received in revised form 13 December 2019; Accepted 2 January 2020 * Corresponding author. E-mail address: ictio@icb.ufmg.br (E. Rizzo). Ecotoxicology and Environmental Safety 190 (2020) 110165 0147-6513/ © 2020 Published by Elsevier Inc. T