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Pervasive mercury contamination of a semi-aquatic apex predator across the Pantanal wetland

Published online by Cambridge University Press:  13 August 2025

Nathalie Foerster Open the ORCID record for Nathalie Foerster [Opens in a new window] ,
Grazielle Soresini Open the ORCID record for Grazielle Soresini [Opens in a new window] ,
Caroline Leuchtenberger Open the ORCID record for Caroline Leuchtenberger [Opens in a new window] ,
Daniela de Assis Bócoli ,
Janaíne de Brito Paiva ,
Carlos Henrique Hoff Brait  and
Guilherme Mourão Open the ORCID record for Guilherme Mourão [Opens in a new window]
Nathalie Foerster*
Affiliation:
Programa de Pós-Graduação Em Ecologia e Conservação, Universidade Federal de Mato Grosso do Sul, Campo Grande, Brazil Projeto Ariranhas/Giant Otter Conservation Fund, Arroio do Meio, Brazil IUCN Species Survival Commission, Otter Specialist Group, Gland, Switzerland Laboratório de Vida Selvagem, Embrapa Pantanal, Corumbá, Brazil
Grazielle Soresini
Affiliation:
Projeto Ariranhas/Giant Otter Conservation Fund, Arroio do Meio, Brazil IUCN Species Survival Commission, Otter Specialist Group, Gland, Switzerland
Caroline Leuchtenberger
Affiliation:
Projeto Ariranhas/Giant Otter Conservation Fund, Arroio do Meio, Brazil IUCN Species Survival Commission, Otter Specialist Group, Gland, Switzerland Laboratório de Vida Selvagem, Embrapa Pantanal, Corumbá, Brazil Instituto Federal Farroupilha, Santa Maria, Brazil
Daniela de Assis Bócoli
Affiliation:
Grupo Exata Brasil, Jataí, Brazil
Janaíne de Brito Paiva
Affiliation:
Grupo Exata Brasil, Jataí, Brazil
Carlos Henrique Hoff Brait
Affiliation:
Grupo Exata Brasil, Jataí, Brazil
Guilherme Mourão
Affiliation:
Programa de Pós-Graduação Em Ecologia e Conservação, Universidade Federal de Mato Grosso do Sul, Campo Grande, Brazil Laboratório de Vida Selvagem, Embrapa Pantanal, Corumbá, Brazil
*
Corresponding author: Nathalie Foerster; Email: nathalie.foerster@gmail.com
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Summary

As apex predators, giant otters (Pteronura brasiliensis) are susceptible to the bioaccumulation of heavy metals, particularly in regions where gold-mining contributes to mercury (Hg) pollution. This is the broadest-scale study assessing Hg and selenium (Se) concentrations in the Pantanal. Samples from 10 sites across the Pantanal were analysed using inductively coupled plasma mass spectrometry. We constructed a two-factor generalized additive model (GAM) to investigate the relationship between Hg concentrations in giant otters and their location along river courses in gold-mining areas. To determine the feasibility of merging the dataset from the present study with the dataset of a previous study carried out by our group during 2016–2017, we included the datasets as a factor in the analysis. The GAM results supported the feasibility of merging the datasets. Additionally, we measured Se concentrations due to their potential to mitigate Hg toxicity. Higher Hg levels were found in otters from watercourses near gold-mining areas, with concentrations decreasing downstream, revealing a contamination gradient and the extensive impact of local pollution on wetlands. The highest Hg concentration was recorded in the Bento Gomes River, within a gold-mining area, whereas otters from unconnected sites exhibited lower Hg levels.

Keywords

Giant ottergold-miningmercury toxicityPteronura brasiliensistoxic elements

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Type
Report
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Environmental Conservation , Volume 52 , Issue 4 , December 2025 , pp. 233 - 238
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Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Foundation for Environmental Conservation

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