Before the dam: a fish-mercury contamination baseline survey at the Xingu river, Amazon basin before the Belo Monte dam

• Autor(a) principal: Araujo, Juliana Souza
• Data de Publicação: 2021
• Outros Autores: Andrades, Ryan, Hauser-Davis, R. A, Lima, Marcelo de Oliveira, Giarrizzo, Tommaso
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Digital do Instituto Evandro Chagas (Patuá)
• Texto Completo: https://patua.iec.gov.br/handle/iec/4434
• topic: Peixes / anatomia & histologia; Peixes / anormalidades; Intoxicação por Mercúrio; Isótopos de Mercúrio; Cadeia Alimentar; Barragens; Reservatório de Belo Monte; Centrais Hidrelétricas; Belo Monte (PA); Rio Xingu (PA)

In the last decades, mega-diverse rivers worldwide (e.g., the Amazon and their tributaries) have experienced several human-driven transformations, although impact assessments oftentimes lack baseline data or reference values to better estimate observed disturbances. Herein, we assessed THg and δ15N in fish muscle tissue to determine biomagnification processes, also including seasonal assessments, concerning Hg in fish from the Belo Monte reservoir, located on the Xingu River, prior to its impoundment. A total of 312 samples from 19 fish species belonging to distinct feeding guilds were sampled. None presented THg concentrations above the threshold levels of 0.5 μg g−1 established by the World Health Organization. However, biomagnification was observed (R = 0.8; p < 0.001), also confirmed by a trophic magnification factor of 1.76 for the entire food web. The THg content in the water was less than 0.001 mg L−1 and only Hemiodus unimaculatus presented seasonal variations for THg. Therefore, at the time of this study, the Xingu River presented low Hg contamination levels in both water and target fish.