title: Mercury concentrations in different tissues of turtle and caiman species from the Rio Purus, Amazonas, Brazil.
abstract: Total mercury (Hg) concentrations of muscle, liver, blood, and epidermal keratin were measured in typically consumed, economically and culturally important species of turtle (Podocnemis unifilis and Podocnemis expansa) and caiman (Melanosuchus niger and Caiman crocodilus) from the Rio Purus in the Amazon basin, Brazil. Methylmercury (MeHg) concentrations were also measured in muscle tissue, representing the first analysis of MeHg concentrations in Amazonian reptile species. In muscle tissues Hg was mostly MeHg (79-96%) for all species. No correlations existed between animal size and total Hg or MeHg concentrations for any species other than M. niger, possibly as a result of growth dilution or the evolution of efficient Hg elimination mechanisms. Significant linear correlations were found between total Hg concentrations in all pairs of nonlethally sampled tissues (keratin and blood) and internal tissues (muscle and liver) for M. niger and between keratin and internal tissues for P. expansa, indicating that nonlethally sampled tissues can be analyzed to achieve more widespread and representative monitoring of Hg bioaccumulation in Amazonian reptiles. Although mean Hg concentrations in muscle for all species were below the World Health Organization guideline for safe consumption (500 µg kg(-1)), mean concentrations in caiman liver were above the safe limit for pregnant women and children (200 µg kg(-1)). No significant differences were found between total Hg and MeHg concentrations in tissues from wild-caught and farm-raised P. expansa, suggesting that farming may not reduce Hg exposure to humans.
authors.affiliation: Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia.
authors.forename: Sam
authors.initials: S
authors.lastname: Eggins
authors.affiliation: Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia.
authors.forename: Larissa
authors.initials: L
authors.lastname: Schneider
authors.affiliation: Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia.
authors.forename: Frank
authors.initials: F
authors.lastname: Krikowa
authors.affiliation: Coordenacao de Biodiversidade, Instituto Nacional de Pesquistas da Amazônia, Manaus, Amazonas, Brazil.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Vogt
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil.
authors.forename: Ronis
authors.initials: R
authors.lastname: Da Silveira
authors.affiliation: Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Maher
mesh_terms: D000489:Alligators and Crocodiles / Q000378:metabolism*; D000818:Animals; D017756:Aquaculture; D049628:Body Size; D001938:Brazil; D004784:Environmental Monitoring; D006801:Humans; D007633:Keratins / Q000032:analysis; D008099:Liver / Q000737:chemistry; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis / Q000378:metabolism; D018482:Muscle, Skeletal / Q000737:chemistry; D012727:Sex Characteristics; D013045:Species Specificity; D014018:Tissue Distribution; D014426:Turtles / Q000378:metabolism*
chemical_list: D008767:Methylmercury Compounds; D007633:Keratins; D008628:Mercury
keywords: Amazon; Bioaccumulation; Mercury; Methylmercury; Reptile