Elemental concentrations in skin and internal tissues of Commerson’s dolphins (Cephalorhynchus commersonii) from subantarctic waters

Abstract

The skin of cetaceans is the most accessible tissue, and its sampling has been proposed as a noninvasive method to evaluate trace element concentrations in free-ranging populations. In the present work, concentrations of essential (Cl, Na, K, Mg, Fe, Zn, Mn and Co), nonessential (As and Ag), and of unknown essentiality (Br, Rb and Cs) elements were determined in the skin from nine by-caught Commerson’s dolphins (Cephalorhynchus commersonii) from Tierra del Fuego, Argentina. Skin correlations with internal tissues—lung, liver, kidney and muscle—were assessed to evaluate how the skin represents internal element concentration for monitoring purposes. Elemental contents were analyzed by instrumental neutron activation analysis (INAA). Regarding tissue distribution, skin had the highest concentration of Zn being two orders of magnitude higher than internal tissues, while other elements such as Co and Rb had similar concentrations among tissues. High mean concentrations of Cl, Na, Mg, Br and Mn were observed in the lung and liver. Our results support the use of skin to evaluate Fe, Br and Rb concentrations in internal tissues for biomonitoring purposes; however, other elements did not show significant skin-to-tissue correlations. Overall, toxic element levels were far below concentrations found to cause harm in marine vertebrates. This study provided baseline data on elemental concentrations in tissues of Commerson’s dolphins in subantarctic waters from the South Atlantic Ocean.