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Using Skuas to monitore Mercury in Antarctic environment: What is the best feather to analyse?

Apresentado originalmente no: SCAR Open Science Conference, Buenos-Aires, 3-6 August 2010

Adriana Rodrigues de Lira Pessoa, Erli Schneider Costa, Maria Alice dos Santos Alves, João Paulo Machado Torres, Olaf Malm.

Abstract: Skuas are seabirds at the top of food chain, thus they are susceptible to the accumulation of metals, as mercury (Hg). It is an especially toxic metal; thus its levels must be appropriately monitored in different species. Feathers are considered non-destructive indicators of contamination. The present study aimed to compare Hg levels in feathers taken from different sites of the body of two south polar skuas (Catharacta maccormicki) found dead in King George Island (Hennequin Point and Keller Peninsula). For the analyses feathers were taken from the breast, abdomen, back, head/neck, wing and tail of the birds. All Hg levels were analyzed in the Laboratório de Radioisótopos Eduardo Penna Franca (UFRJ) using an adapted methodology for digestion and analysis of Hg levels in human hair (Bastos 1997). To statistical analyses we grouped the similar feathers of the body in two groups (breast, abdomen, back and head/neck – countor feathers and tail/wing, flight ones). The results were standardized with the mass of the samples and we used levels of Hg in ppm. The first results shown significant differences between Hg levels in countor and in flight feathers (Mann Whitney test, U´ = 54; p<0.05). This indicates that it is indispensable to use the feathers sampled from the same part of the body for the analysis during the period of the study. On the other hand is important to consider how much invasive is the sampling and what is the question to answer to adjust the methodology. (This work was supported by The National Council for Scientific and Technological Development, Brazilian Antarctic Program and Ministery of Science and Technology (CNPq/PROANTAR 550040/2007-2 and CNPq/MCT 557049/2009-1). ESC received a CNPq fellowship (141474/2008-4), and MASA received a CNPq grant (3027185/03-6).