Latitudinal and sex differences in mercury contamination of brown skuas in the Southern Ocean

MILLS, W; IBAÑEZ, ANDRÉS E; BUSTAMANTE, PACO; CARNEIRO, ANA; BEARHOP, STUART; CHEREL, YVES; MARIANO Y JELICICH, ROCÍO; MCGILL, RONA; MONTALTI, DIEGO; VOTIER, S; PHILLIPS, R

Congreso; 3rd World Seabird Conference; 2021

Brown skuas (Stercorarius antarcticus lonnbergi) are opportunistic predators and scavengers. Here, we measured total mercury (THg) concentrations in blood samples from adult brown skuas (n = 82) from three breeding sites across a latitudinal gradient in the Southern Ocean (SW Atlantic region): (i) Bahía Esperanza/Hope Bay, Antarctic Peninsula; (ii) Signy Island, South Orkney Islands; and, (iii) Bird Island, South Georgia. Blood THg concentrations increased from high Antarctic to low Antarctic latitudes, such that Hg contamination was lowest at Bahía Esperanza/Hope Bay (mean ± SD, 0.95 ± 0.45 µg g-1 dw), intermediate at Signy Island (3.42 ± 2.29 µg g-1 dw) and highest at Bird Island (4.47 ± 1.10 µg g-1 dw). Blood THg concentrations were also related positively to δ15N values, reflecting the biomagnification process. Males had higher Hg burdens than females, likely reflecting deposition into the egg by females and potentially differences in trophic ecology. These data provide important insights into Hg transfer to Southern Ocean seabirds.