title: Low total mercury in Caiman yacare (Alligatoridae) as compared to carnivorous, and non-carnivorous fish consumed by Amazonian indigenous communities.
abstract: 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.
authors.affiliation: Wildlife Conservation Society, Greater Madidi-Tambopata Landscape Conservation Program, La Paz, Bolivia.
authors.forename: S J
authors.initials: SJ
authors.lastname: Rivera
authors.affiliation: Colección Boliviana de Fauna, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia.
authors.forename: L F
authors.initials: LF
authors.lastname: Pacheco
authors.affiliation: Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia. Electronic address: dacha@fcpn.edu.bo.
authors.forename: D
authors.initials: D
authors.lastname: Achá
authors.affiliation: Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia; Instituto de Ecología, Unidad de Limnología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia.
authors.forename: C I
authors.initials: CI
authors.lastname: Molina
authors.affiliation: Wildlife Conservation Society, Greater Madidi-Tambopata Landscape Conservation Program, La Paz, Bolivia; Instituto de Ecología, Unidad de Limnología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia.
authors.forename: G
authors.initials: G
authors.lastname: Miranda-Chumacero
mesh_terms: D000489:Alligators and Crocodiles / Q000378:metabolism*; D000818:Animals; D001822:Body Burden; D001838:Bolivia; D004784:Environmental Monitoring; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D006801:Humans; D008628:Mercury / Q000032:analysis / Q000378:metabolism*; D010473:Perciformes / Q000378:metabolism; D044382:Population Groups; D045483:Rivers; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Bioaccumulation; Biomagnification; Health of indigenous peoples; Mercury exposure