Genetic and toxicological status of southern elephant seals (Mirounga leonina) around Antarctic waters with emphasis on the colony at Isla 25 de Mayo (King George Island), South Shetland Islands, Antarctic Peninsula

DALIA C. BARRAGÁN-BARRERA; FEDERICO G. RIET-SAPRIZA; ALEJANDRO QUIROGA; MOJICA-MONCADA DIEGO F; JAVIER NEGRETE; LUCAS LANUSSE; ANTONIO CURTOSI; ANDREA LUNA-ACOSTA; PACO BUSTAMANTE; SUSANA CABALLERO

Hobart

Conferencia; 9th SCAR OPEN SCIENCE CONFERENCE; 2020

Scientific Committee on Antarctic Research

The southern elephant seal (SES) (Mirounga leonina) has a circumpolar distribution, breeding mainly on sub Antarctic islands, and making long trips between breeding colonies, molting locations and foraging areas, exposing to pollutants such as mercury (Hg). Although individuals show fidelity to a set of established breeding colonies, their migratory habits may allow long-range gene flow. To assess the Hg concentrations and genetic status of SES on the colony at Isla 25 de Mayo (KGI; 62º15?S, 58º39?W), skin samples from free ranging individuals (n=60) were collected using a remote biopsy dart during 2015-2016 austral summer. Toxicological results indicated that SES Hg concentrations ranged between 142-1,915 ng/g (mean=730 ng/g, SD=388), values higher than reported for humpback whales skin in western Antarctic Peninsula (mean=35 ng/g, SD=3.7, n=14), due likely to feeding ecology (whales prey on krill whereas SES consume fish and squid). Regarding genetics, the mitochondrial DNA Control-Region results showed a high haplotype diversity, and indicated that SES from KGI are closely related with individuals from Elephant Island, Livingston Island, and Islas Malvinas (Falkland Islands), but maintained restricted genetic flow with individuals from Macquarie Island and the now extinct colony from Victoria Land Coast. Microsatellite analyses confirmed high genetic diversity. Parentage analyses identified 2% of individuals in the sample as mother-offspring, 16% as full/half siblings and 82% as unrelated individuals. These results agree with previous findings of long-distance genetic dispersal mediated mainly by SES males. Due to large feeding range, SES can be a good sentinel to continue pollutant monitoring in Antarctic and sub-Antarctic waters.