Agreement on the Conservation of Albatrosses and Petrels

Organic mercury levels have increased over time in Black-footed Albatross feathers

Anh-Thu Vo of the Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, USA and colleagues have studied the increase over 120 years of methylmercury levels in museum-plucked feathers of Black-footed Albatrosses Phoebastria nigripes, publishing their findings this month open-access in PNAS (Proceedings of National Academy of Sciences of the United States of America).

The paper's abstract follows:

"Methylmercury cycling in the Pacific Ocean has garnered significant attention in recent years, especially with regard to rising mercury emissions from Asia.  Uncertainty exists concerning whether increases in anthropogenic emissions over time may have caused increased mercury bioaccumulation in the biota.  To address this, we measured total mercury and, for a subset of samples, methylmercury (the bioaccumulated form of mercury) in museum feathers from an endangered seabird, the black-footed albatross (Phoebastria nigripes), spanning a 120-y period.  We analyzed stable isotopes of nitrogen (δ15N) and carbon (δ13C) to control for temporal changes in trophic structure and diet.  In post-1940 and -1990 feathers, we detected significantly higher mean methylmercury concentrations and higher proportions of samples exhibiting above deleterious threshold levels (∼40,000 ng·g-1) of methylmercury relative to prior time points, suggesting that mercury toxicity may undermine reproductive effort in the species.  We also found higher levels of (presumably curator-mediated) inorganic mercury in older specimens of albatross as well as two nonpelagic species lacking historical exposure to bioavailable mercury, patterns suggesting that studies on bioaccumulation should measure methylmercury rather than total mercury when using museum collections.  δ15N contributed substantially to models explaining the observed methylmercury variation.  After simultaneously controlling for significant trends in δ13C over time and δ15N with methylmercury exposure, year remained a significant independent covariate with feather methylmercury levels among the albatrosses.  These data show that remote seabird colonies in the Pacific basin exhibit temporal changes in methylmercury levels consistent with historical global and recent regional increases in anthropogenic emissions."

Reference:

Vo, A.-T.E., Bank, M.S., Shine, J.P. &. Edwards, S.V. 2011.  Temporal increase in organic mercury in an endangered pelagic seabird assessed by century-old museum specimens.  www.pnas.org/cgi/doi/10.1073/pnas.1013865108.

See also: http://www.bbc.co.uk/news/science-environment-13121088

John Cooper, ACAP Information Officer, 28 April 2011