title: An evaluation of the use of reptile dermal scutes as a non-invasive method to monitor mercury concentrations in the environment.
abstract: Reptiles are ideal organisms for the non-invasive monitoring of mercury (Hg) contamination. We have investigated Hg bioaccumulation in tissue layers of reptile dermis as a basis for establishing a standardized collection method for Hg analysis. Tissue samples from freshwater turtle species Podocnemis unifilis and Podocnemis expansa and caiman species Melanosuchus niger and Caiman crocodilus, all from the Amazonian region, were analysed in this study. We first tested the relationships between Hg concentrations in keratin and bone to Hg concentrations in muscle to determine the best predictor of Hg concentration in muscle tissue. We then investigated the potential for measuring Hg concentrations across turtle carapace growth rings as an indicator of longer term changes in Hg concentration in the environment. Hg concentrations were significantly lower in bone (120 ng g(-1) caimans and 1 ng g(-1) turtles) than keratin (3600 ng g(-1) caimans and 2200 ng g(-1) turtles). Keratin was found to be a better predictor of exposure to Hg than muscle and bone tissues for both turtles and caimans and also to be a reliable non-invasive tissue for Hg analysis in turtles. Measurement of Hg in carapace growth rings has significant potential for estimating Hg bioaccumulation by turtles over time, but full quantification awaits development and use of a matrix-matched reference material for laser ablation ICPMS analysis of Hg concentrations in keratin. Realising this potential would make a valuable advance to the study of the history of contamination in mining and industrial sites, which have until now relied on the analysis of Hg concentrations in sediments.
authors: University of Canberra, Institute for Applied Ecology, Kirinary St., Canberra, ACT, Australia. Electronic address: laris.schneider@gmail.com.
authors: Larissa
authors: L
authors: Schneider
authors: University of Canberra, Institute for Applied Ecology, Kirinary St., Canberra, ACT, Australia.
authors: Sam
authors: S
authors: Eggins
authors: University of Canberra, Institute for Applied Ecology, Kirinary St., Canberra, ACT, Australia.
authors: William
authors: W
authors: Maher
authors: Instituto Nacional de Pesquisas da Amazônia, Coordenacao de Biodiversidade, Av. André Araujo 2223, Aleixo, CEP: 69080-971 Manaus, AM, Brazil.
authors: Richard C
authors: RC
authors: Vogt
authors: University of Canberra, Institute for Applied Ecology, Kirinary St., Canberra, ACT, Australia.
authors: Frank
authors: F
authors: Krikowa
authors: Australian National University, Research School of Earth Sciences, Canberra 0200, Australia.
authors: Les
authors: L
authors: Kinsley
authors: Australian National University, Research School of Earth Sciences, Canberra 0200, Australia.
authors: Stephen M
authors: SM
authors: Eggins
authors: Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Rua General Rodrigo Otávio Num. 3000, Mini-Campus Coroado, CEP: 66077070 Manaus, AM, Brazil.
authors: Ronis
authors: R
authors: Da Silveira
mesh_terms: D000489:Alligators and Crocodiles / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D001938:Brazil; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis* / Q000493:pharmacokinetics; D004817:Epidermis / Q000378:metabolism*; D005618:Fresh Water; D007633:Keratins / Q000737:chemistry*; D013058:Mass Spectrometry; D008628:Mercury / Q000032:analysis* / Q000493:pharmacokinetics; D018482:Muscle, Skeletal / Q000378:metabolism; D014426:Turtles / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D007633:Keratins; D008628:Mercury
keywords: Amazon; Caiman; Carapace; Hg history; Laser ablation; Turtle