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dc.contributor.authorBryan, Anna Laura
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2014
dc.description.abstractStomach contents, stable isotopes, fatty acids, and more recently fecal DNA are commonly used to infer the diet of marine mammals. However, how complementary or contradictory these methods are, especially when considering individual diet variability, remains poorly understood. This study assessed the differences in the dietary information resulting from stomach contents, stable isotopes, and fatty acids for adult bearded seals (Erignathus barbatus), and fishes identified from stomach contents and fecal DNA for bearded and ringed seals (Pusa hispida), harvested in Alaska for subsistence use. Stomach contents and fecal DNA provided information on recently consumed prey. In contrast, stable carbon and nitrogen isotopes of muscle and fatty acid profiles of blubber provided information on prey consumed and integrated over a longer time frame, but taxonomic resolution of prey was low. Overall, stomach contents provided the most dietary data, while fecal DNA delivered the least. Using denaturing gradient gel electrophoresis (DGGE) of 16S gene fragments, only 40% of the fecal samples (12 bearded and one ringed seal) produced detectable DNA suitable for reference gene amplification. Only three fish species could be positively identified in the diet of seals (Arctic cod, Boreogadus saida; shorthorn sculpin, Myoxocephalus scorpius; and an unknown snailfish species, Liparidae) when using fecal DNA. In a dietary comparison, and despite differences in dietary time frames, the relative occurrence (RO) of prey from stomach contents and the mean proportions of prey source groups from a Bayesian stable isotope mixing model (SIAR) were similar. The proportions of indicator fatty acids from full-thickness blubber, such as 16:4n-1, 20:5n-3, 20:4n-6, 20:1n-9, 22:1n-11, and the presence of non-methylene-interrupted fatty acids were similar to other fatty acid studies of bearded seals in Alaska, and suggest a benthic diet. Overall, the methods yielded different, but not necessarily contradictory results.en_US
dc.description.tableofcontentsChapter 1: General Introduction -- Chapter 2: Identifying bearded seal diet: a comparison of individual seals using stomach contents, stable isotopes, and fatty acids -- Chapter 3: Fish prey in bearded and ringed seal diet: a comparison of stomach contents and fecal DNA -- Chapter 4: General Conclusion.en_US
dc.titleIdentifying bearded and ringed seal diet - a comparison of stomach contents, stable isotopes, fatty acids, and fecal dnaen_US
dc.identifier.departmentDepartment of Biology and Wildlife
dc.contributor.chairHundertmark, Kris
dc.contributor.chairHorstmann-Dehn, Lara
dc.contributor.committeeHardy, Sarah
dc.contributor.committeeQuakenbush, Lori

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  • Biological Sciences
    Includes WIldlife Biology and other Biological Sciences. For Marine Biology see the Marine Sciences collection.

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