Stable isotope food-web analysis and mercury biomagnification in polar bears ( Ursus maritimus )

• Published in: Polar Research
• Main Authors: Horton, Travis W., Blum, Joel D, Xie, Zhouqing, Hren, Michael, Chamberlain, C. Page
• Other Authors: 2 Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005, USA, 1 Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand, 3 Geology and Geophysics Department, Yale University, P.O. Box 208109, New Haven, CT 06520-8109, USA, 4 Geological and Environmental Science Department, Stanford University, Stanford, CA 94305-2115, USA
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Blackwell Publishing Ltd 2009
• Subjects: Arctic; Food Webs; Pelagic; Polar Bears; Stable Isotopes; Sympagic; Geology and Earth Sciences; Science; Antarctica Journal; Polar Research; Ursus maritimus
• Online Access: http://hdl.handle.net/2027.42/73930; https://doi.org/10.1111/j.1751-8369.2009.00114.x

Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric Hg deposition associated with snow and ice. Here, we report on stable carbon and nitrogen isotope ratios, and Hg concentrations, determined for 26, late 19th and early 20th century, polar bear ( Ursus maritimus ) hair specimens, collected from catalogued museum collections. These data elucidate relationships between the high-latitude marine food-web structure and Hg concentrations in polar bears. The carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. Our results show a positive correlation between polar bear hair Hg concentrations and δ 15 N. Interpretation of the stable isotope data in combination with Hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/73930/1/j.1751-8369.2009.00114.x.pdf