Low total mercury in Caiman yacare (Alligatoridae) as compared to carnivorous, and non-carnivorous fish consumed by Amazonian indigenous communities

S. J. Rivera, L. F. Pacheco, D. Achá, C. I. Molina, G. Miranda-Chumacero

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Mercury contamination in the River Beni basin is an important health risk factor, primarily for indigenous communities that live along the river. Among them are the Tacana, living in their original territory with sustainable use of their natural resources, consuming fish, Caiman yacare, and other riverine resources as their main source of protein. To assess mercury exposure to Tacana people, total mercury (THg) was evaluated in the muscle of seven commercial fish, and Caiman yacare (yacare caiman) during 2007 and 2008. THg was extracted by acid digestion and concentrations were determined by atomic absorption spectrometry. Mean mercury concentrations in C. yacare was 0.21 ± 0.22 μg g−1Hg w.w. (wet weight), which is lower than expected given its high trophic level, and its long life-span. It is possible that mercury in C. yacare is accumulated in other organs, not included in this study; but it is also possible that physiological mechanisms are involved that help caimans get rid of ingested mercury, or simply that C. yacare's diverse diet reduces THg accumulation. Carnivorous fishes (Pygocentrus nattereri, Pseudoplatystoma tigrinum, Zungaro zungaro, Plagioscion squamosissimus, and Leiarius marmoratus) had the highest total mercury concentrations, ranging from 0.35 to 1.27 μg g−1Hg w.w. moreover, most were above the limit recommended by WHO (0.5 μg g−1Hg w.w.); except for Leiarius marmuratus, which presented a mean of 0.353 ± 0.322 μg g−1Hg w.w. The two non-carnivorous fish species (Prochilodus nigricans, and Piaractus brachypomus) present mean concentrations of 0.099 ± 0.027, and 0.041 ± 0.019 μg g−1Hg w.w., respectively. Finally, recommendations on the consumption habits of Tacana communities are discussed.

Original languageEnglish
Pages (from-to)366-371
Number of pages6
JournalEnvironmental Pollution
StatePublished - 1 Nov 2016

Bibliographical note

Funding Information:
The Wildlife Conservation Society through the Greater Madidi-Tambopata Landscape Conservation Program funded this research with support from Gordon and Betty Moore Foundation, John D. and Catherine T. MacArthur Foundation and the blue moon fund. We extend our particular thanks to fishermen and caiman managers in local communities. We would also like to thank Jaime Chincheros of the Institute of Ecology and Environmental Quality Laboratory (LCA), and Jean Louis Duprey of Institut de Recherche pour le Développement (IRD) for their support in the execution of this study. Marc Pouilly commented on an earlier version of this manuscript.

Publisher Copyright:
© 2016 Elsevier Ltd


  • Bioaccumulation
  • Biomagnification
  • Health of indigenous peoples
  • Mercury exposure


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