CONICET | Buscador de Institutos y Recursos Humanos

Odontocetes are upper level predators in food webs and therefore are subject to high levels of heavy metal accumulation being proposed as marine pollution sentinels worlwide. As a consequence, monitoring the exposure to trace elements is a key factor for the conservation of wild marine mammals. Epidermis is an accessible tissue and its sampling has been proposed as a noninvasive method to assess ecotoxicological risk in free-ranging animals. We aim to test whether epidermis is a suitable tissue to predict trace element concentrations in internal tissues (liver, kidney, muscle and lung) of Commerson?s dolphins from Tierra del Fuego, Argentina. Concentrations of essential (Cl, Na, K, Mg, Fe, Zn, Mn, Co and Se), nonessential (Hg, As and Ag), and of unknown essentiality (Br, Rb and Cs) elements were analized in bycaught specimens. Elemental concentrations were determined by instrumental neutron activation analysis. We found epidermis had the highest concentration of Zn and Se being up two orders of magnitude higher than internal tissues, while Co and Rb had similar concentrations among tissues. High concentrations of Cl, Na, Mg, Br and Mn were observed in lung and liver, also levels of Hg and Ag were higher in hepatic tissue. Regarding skin-to-internal-tissue relationship significant positive correlations were found between Hg in epidermis and all other internal tissues analized. Also Fe, Br and Rb concentrations in epidermis showed positive relationships with levels in internal tissues; e.g. skin Fe correlates with liver contents; Br correlates with kidneys; and Rb correlates with liver and muscle, possibly given their capacity to bioaccumulate them. Other essential elements did not show any correlation, owing to essential trace element homeostasis which provides an independent organ regulation. Our results support the use of epidermis as a surrogate to monitor Hg, Fe, Br and Rb concentrations in subantarctic dolphins from South Atlantic Ocean.