Mercury concentrations in bats (Chiroptera) from a gold mining area in the Peruvian Amazon
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In the southeastern Peruvian Amazon, artisanal and small-scale gold mining (ASGM) is estimated to have released up to 300 tonnes of mercury (Hg) to the environment between 1995 and 2007 alone, and is claimed to be responsible for Hg concentrations above international thresholds for aquatic wildlife species. Here, we examined whether Hg concentrations in bat populations are potentially related to regional ASGM-Hg releases. We determined Hg concentrations in the fur of bats collected at three different distances from the major ASGM areas in Peru. Our findings from 204 individuals of 32 species indicate that Hg concentrations in bat fur mainly resulted from differences in feeding habits, because Hg concentrations were significantly higher in omnivorous bats than in frugivorous bats. At least in two species, populations living in ASGM-affected sites harbored higher Hg concentrations than did populations in unaffected sites. Because Hg concentrations reflect Hg dietary exposure, Hg emissions from amalgam roasting sites appear to deposit locally and enter the terrestrial food web. Although our study demonstrates that ASGM activities (and Hg point sources) increase Hg exposure in wildlife, the overall Hg concentrations reported here are relatively low. The measured Hg concentrations were below the toxicity threshold at which adverse neurological effects have been reported in rodents and mink (>10 µg g−1), and were in the range of Hg concentrations in the fur of bats from nonpoint source affected sites in other latitudes. This study emphasizes the importance of considering feeding habits when evaluating Hg concentrations in bats and other vertebrates.
KeywordsMercury Hg Gold mining Bats Amazon rainforest wildlife
This research was partially funded by Tambopata Reserve Society (TReeS), World Wildlife Foundation (WWF-Peru), and AG Umweltgeochemie—TU Braunschweig. We are greatful for the logistic support of Servicio Nacional de Areas Protegidas por el Estado (Sernanp), Servicio Nacional Forestal y de Fauna Silvestre (Serfor), Asociación para la Investigación y Desarrollo Integral (Aider), as well as of Jose Luis Mena and Nadesna Cortes. Thanks to Katherin Bernabé, Emilio Bonifaz, Deyber Gil, Werner Pinedo, and Fredy Mollehuanca for their assistance in the field. We appreciate the guidance on the data treatment and the constructive comments of Dagmar Söndgerath, Johan Rydberg, Dania Richter, and Marta Pérez-Rodríguez that greatly helped to improve the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing financial interests.
This article does not contain any studies with human participants. Capture and handling of bats were conducted under the research permit (N° 006-2015-SERNANP-JEF) obtained from the Peruvian authorities of the national protected areas (Sernanp).
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