COMMERSON'S DOLPHINS (CEPHALORHYNCHUS C. COMMERSONII) SKIN AS ELEMENTAL POLLUTANTS BIOMONITOR

CÁCERES SAEZ, I.; RIBEIRO GUEVARA, S.; GOODALL, R.N.P.; DELLABIANCA, N.; CAPPOZZO, L.

Cartagena de las Indias

Congreso; IV Congreso Colombiano de Zoología; 2014

Asociación Colombiana de Zoología

In order to evaluate the use of skin samples as a tool for assessing elemental contents in small cetaceans, the concentration of essential (Zn, Fe, Mn, Co and Se) and non-essential (Ag, As, Cd and Hg) elements was determined by Instrumental Neutron Activation Analysis in the skin and internal tissues (liver, kidney, muscle, lung, and spleen) of nine Commerson?s dolphins. All specimens were collected from by-caught events during the 2009 - 2011 austral summers on the shores of Tierra del Fuego, Argentina. Full necropsies were performed and samples were collected and processed following standardized procedures for the analysis of elemental contents in trace levels. The results disclosed high levels of Zn, 1058(163) μg g-1 dry weight (DW) (standard deviation in parenthesis) and Se, 92.8(18.3) μg g-1 DW in the skin, whereas internal tissues showed significant low levels. Selenium and Zn enrichment in the skin is consistent with that of cetacean?s world-wide. This might be implies specific functions of the epidermis such as protection against UV-radiation and healing wounds. Toxic element concentrations such as Hg and Ag in the skin were significantly lower than in the liver, kidney, lung, muscle and spleen; however As concentration were similar among all tissues analyzed. Cadmium concentration was below the detection limit in all skin samples. Among heavy metals, Hg was the only one showing significant correlations between the skin concentration and those in kidney (R2=0.80, p = 0.01), liver (R2=0.38, p = 0.04), lung (R2=0.83, p = 0.007) and muscle (R2=0.82, p = 0.0004) across all individuals. This validate that skin can be used as suitable monitoring tissue to assess Hg accumulation in internal tissues, and their associated toxicological risks for cetacean populations. No significant tissue-to-skin correlations for the other elements were found and therefore cannot predict elemental concentrations in internal tissues. Additionally no age-related increase of the elements concentration in the skin was observed among the specimens under study; nevertheless, adult specimens had maximum Hg content in all tissues under study. Our results suggest that epidermal samples of Commerson?s dolphins provide valuable information on the status of Hg contents for subantarctic waters, encourages extending the actual opportunistic sampling based on tissues collected on stranded individuals on the southwestern South Atlantic Ocean.