Bruno Souza, Chico Mendes Institute for Biodiversity Conservation (ICMBio), and Fabióla Domingus Moreira, National Institute of Amazonian Research (INPA)

Aiming to characterize the level of contamination of fish by mercury and risks to human consumption, a multidisciplinary staff coordinated by Bruno Souza from the Chico Mendes Institute for Biodiversity Conservation (ICMBio) and Fabíola Domingos-Moreira from the National Institute of Amazonian Research (INPA) embarked on an expedition to collect fish and water samples from 29 October–9 November 2018 on Rio Branco basin in Roraima, Brazil.

Staff investigating water samples

The multidisciplinary staff investigated fish and water samples from the Rio Branco basin in Roraima.

Fish from the rivers Branco, Mucajaí and Uraricoera, including specimens purchased in fish markets in the cities of Caracaraí and Mucajaí were collected. More than 2,000 samples of tissues, scales, fins, blood and vital organs were collected from 240 fish. The result about the possible contamination of fish by heavy metals is anticipated to be available later this year.

According to researcher Romério Bríglia, from ICMBio/RR, fishing is an extremely important activity in the state, with over 6,000 professional fisherman currently engaged in this activity, which is an important source of food and income in Roraima.

Researcher Domingos-Moreira states that “the research is important because it is evaluating the presence of mercury and the occurrence of harmful side-effects to the health of the fish. Therefore, this contamination might reflect in the reduction of fish for the population.” The environmental analyst Souza highlights that “the study contributes to the implementation of a monitoring protocol of heavy metals, which, on the other hand, is going to be fundamental for the conservation of the aquatic environment in the Amazon and for the maintenance of quality fish in the region.”

Mercury is used in gold mining and often released in the environment, reaching igarapés, which is what locals call rivers and waterways. Previous studies conducted by the Oswaldo Cruz Foundation (FIOCRUZ) revealed that part of the Yanomami population lives close to the mining areas and already have been shown to have a body burden of mercury.

National Center for Research and Conservation of Amazonian Biodiversity (CEPAM) from ICMBio, Brazilian Agricultural Research Corporation (EMBRAPA), Institute of Support for Science, Technology and Innovation of the State of Roraima (IACTI-RR), Amazonas State University (UEA) and Federal University of Amazonas (UFAM) are partner institutions of this initiative, which was funded by the Ministry of Environment through the program named ARPA, which stands for Amazon Protected Areas (Áreas Protegidas da Amazônia).

Background Information

Roraima is a state with a unique characteristic: it has almost exclusively a single-water basin, the Rio Branco Basin. Historically, the state has faced growth waves of illegal mining activity in its surrounding regions, especially in Indian lands, as well as the capital, Boa Vista, where 65% of the state’s population is concentrated. At the end of the 1980s, the mining activity was at its peak, with more than 30,000 miners in the area which would be later homologated in 1992 as the Indian Land of the Yanomami and returned to historic uses prior to mining activities. However, the area has once again been overrun by mining activities, and this time more intensely, using machines and tractors with a potential to rapidly alter the environment in more devastating ways than previous mining activities. This study and others in the future are aimed to assess what the real impacts of this activity are on the local indigenous populations and the environment.

Authors’ contact information: and

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