Diet history of ice seals using stable isotope ratios in claw growth bands

• Published in: Canadian Journal of Zoology
• Main Authors: Carroll, Sara S., Horstmann-Dehn, Larissa, Norcross, Brenda L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2013
• Subjects: Arctic; Climate change; Erignathus barbatus; Pusa hispida; Sea ice; Alaska
• Online Access: http://dx.doi.org/10.1139/cjz-2012-0137; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjz-2012-0137; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjz-2012-0137

Climate change and sea-ice reduction may lead to modifications of food-web structure in the Arctic, and this may impact foraging of ice-associated predators. We examined the dietary history recorded in cornified claw sheaths of ringed seals (Pusa hispida (Schreber, 1775)) and bearded seals (Erignathus barbatus (Erxleben, 1777)) to describe potential seasonal and interannual changes in their foraging. Seasonal layers of cornified cells deposited in claws can document trophic history up to about 10 years; thereafter, the claws start to wear at the distal end. A total of 38 claws were collected during Alaska Native subsistence harvests in 2008–2010 and seasonal growth bands were examined for stable nitrogen and carbon isotope ratios to assess long-term diet patterns. During 2007 (record ice minimum), proportionally more ringed seals fed at a lower trophic level. Bearded seals may have been foraging more pelagically from 2008 to 2010. Interannual variations and high variability between the two ice seal species and among individual diets illustrate the opportunistic nature and flexibility of ice seals to changes in prey.