Tissue concentrations of essential and toxic elements in stranded false killer whales (Pseudorca crassidens) in Southern South America

CAPPOZZO, L.; AGUAYO-LOBO, A; CÁCERES SAEZ, I.; RIBEIRO GUEVARA, S.; DOUGNAC, C.; ARREDONDO, C.; HARO, D.; BLANK, O.

Lima

Congreso; XII Congreso de la Sociedad Latinoamericana de Especialistas en Mamíferos Acuáticos RT 18; 2018

Sociedad Latinoamericana para el Estudio de Mamíferos Acuáticos

The false killer whale is a large member of Delphinids inhabiting tropical to warm temperate oceans worldwide. Their habits are primarily oceanic, and it has been largely determined from stranding and sighting records. Mass stranding?s are common for the species, and have been reported in South America, although their causes remain unknown. An assessment of toxic (As, Cd, Ni, Ag and Hg); non-essential (Br, Rb and Cs) and essential elements (Co, Cr, Fe, Se, K, Mg, Mn, Cl and Na) in liver, kidney, muscle, lung, spleen, testicle, ovary and uterus was performed in false killer whales stranded in Estrecho de Magallanes, Chile, South America (52°39?12??S - 70°19?57??W) on February, 2013. The concentrations were determined by Instrumental Neutron Activation Analysis on freeze dried samples and expressed on a dry weight basis (DW). Among essential elements, kidney and liver showed highest concentrations of Fe, 1542.5(937) and 915.8(53) μgg−1, respectively. Liver, kidney and testis showed similar Zn concentrations ranging between 109 to 259 μgg−1. Chromium and Mn were higher in liver, kidney, lung and testis with ranges of 2.04 - 3.23 μgg−1 and 3.27 - 6.19 μgg−1; respectively. Chlorine, Na, K and Mg mean concentrations in hepatic tissue varied through physiologic level reported for cetacean species. Concerning pollutants: Cd, As and Ni reached highest concentration of 71.2 μgg−1, 2.5 μgg−1 and 0.21 μgg−1, respectively in kidney. Silver concentrations were higher in liver 8.92(2.1) μgg-1, spleen 2.71(3.5) μgg-1 and testis 1.94(326) μgg-1. Mercury concentrations in liver 1068(234) μgg-1 was markedly higher than in other tissues, additionally Se concentration in liver, 398(75) μgg-1 was the highest. Molar ratio of Se/Hg in liver, lung and muscle were 1 suggesting a Se protection against Hg toxicity. Overall individuals showed marked Hg and Ag pollution suggesting that main exposure route occur through diet. Nevertheless origin of pollutants is indefinite, taking account their home range and trophic habits. This constitutes the first study on elemental concentrations of a large odontocete in South America region, providing insights into their contamination status and possible impacts on health of wild populations.