MEPS 243:261-269 (2002)  -  doi:10.3354/meps243261

Feather mercury levels in seabirds at South Georgia: influence of trophic position, sex and age

Peter H. Becker1,*, Jacob González-Solís2, Brigitte Behrends1, John Croxall3

1Institut für Vogelforschung ŒVogelwarte Helgoland¹, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
2Departamento Biología Animal (Vertebrats), Universitat de Barcelona, Avenida Diagonal 645, 08028 Barcelona, Spain
3British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom

ABSTRACT: We studied the mercury contamination of 13 species of seabirds breeding on Bird Island, South Georgia, in 1998. Total mercury concentrations in body feather samples of birds caught at their breeding colonies were determined. Among the species, grey-headed albatross (8933 ng g-1) and southern giant petrel (7774 ng g-1) showed the highest, and gentoo penguin (948 ng g-1) the lowest body feather mercury concentrations. Mercury levels were negatively correlated with the proportion of crustaceans (mainly krill) in the species¹ diets, suggesting that the trophic level is the most important factor in explaining the variation of mercury concentrations in Antarctic seabirds. In 4 species studied for age effects among adult birds (grey-headed and black-browed albatross, northern and southern giant petrel), no age-dependent variation in mercury levels was found. Sex differences were also assessed: female gentoo penguins had lower mercury levels than males, which may be related to the elimination of part of the mercury body burden by females into eggs. In contrast, northern giant petrel males had lower levels than females, which may be related to a higher consumption by males of carrion from Antarctic fur seals. In grey-headed albatrosses, mercury levels were 113% higher than in 1989, when this species was investigated at the same site, indicating a possible increase in mercury pollution of the Southern Ocean during the last decade.

KEY WORDS: Interspecific variability · Intraspecific variability · Trophic position · Krill diet · Foraging · Temporal trend · Total mercury · Body feathers

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