Blood cells and plasma distribution of mercury, selenium and cadmium in SouthAmerican sea lion females

GERPE, M; RODRÍGUEZ, D; ATKINSON, S; MITCHELL, J; PONCE DE LEÓN, A; MORENO, V

Sydney, Australia

Congreso; 5th SETAC World Congress; 2008

Society for Environmental Toxicology and Chemistry

Since marine mammals are top predators in the marine trophic web, they are considered as good biomonitors of heavy metals. Otaria flavescens, the South American sea lion, is a widely distributed Pinniped, with colonies on both the Atlantic and Pacific coasts of South America. Its diet is composed of fish, squid and crustaceans, which are a source of mercury (fish) and cadmium (squid and crustaceans). Selenium is an essential element that is closely related to mercury detoxification in liver. As marine mammals are protected by law, it is relevant to use non lethal techniques to evaluate metal levels in this group. Blood samples from fourteen sea lion females (nine juveniles and five adults) were taken at Isla de Lobos (35º01?38?S-54º52?55?W, Uruguay) in May 2007. Sea lions were physically restrained and sedated with oral anesthesia (isofluorane). Blood samples were taken from the hind flippers; blood cells and plasma were separated by centrifugation and frozen in liquid nitrogen. Total blood volume was estimated by the Evans Blue dilution method, in order to evaluate the transported burden of metals. Metals were determined by ICP-MS, with a nitric digestion by microwave; data was validated by Certified Reference Material. Both non essential metals were detected in all specimens, including the younger animals, showing higher levels for mercury. Selenium concentrations were higher than mercury and cadmium, with a positive relationship with mercury values. Blood cells presented higher levels than plasma for all metals, although in some specimens high cadmium levels were found in the latter. Increased concentrations with age were found, mainly for mercury and cadmium. The preliminary results found in O. flavescens indicate a metallic partition betweeen both blood fractions is closely related to the biochemical properties of each one, offering valuable information about metallic status in marine mammals.