Variability in polar bear Ursus maritimus stable isotopes in relation to environmental change in the Canadian Beaufort Sea
Bibliographic record
Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 630:215-225 (2019) - DOI: https://doi.org/10.3354/meps13136 Variability in polar bear Ursus maritimus stable isotopes in relation to environmental change in the Canadian Beaufort Sea Nicole Boucher1,*, Andrew E. Derocher1, Evan S. Richardson2 1Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada 2Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Winnipeg, MB R3C 4W2, Canada *Corresponding author: nboucher@ualberta.ca ABSTRACT: Diets of apex predators can be used to understand the effects of environmental changes within an ecosystem and to monitor shifts in community dynamics. Using stable isotopes of nitrogen and carbon (δ15N and δ13C) in polar bear Ursus maritimus guard hairs, we examined their diet in the Canadian Beaufort Sea from 2003 to 2011. We investigated how δ15N and δ13C were related to population demographics, sea ice dynamics, climate indices, air temperatures, and ringed seal Pusa hispida ovulation rates. Bayesian stable isotope models were used to determine annual variation in prey contributions and niche widths. Diet contributions from ringed seal, bowhead whale Balaena mysticetus, beluga Delphinapterus leucas, and bearded seal Erignathus barbatus varied by sex, reproductive status, and year. Polar bear ringed seal consumption was lowest and niche widths were highest in 2004 following ringed seal reproductive failure in the early 2000s, and polar bear δ15N decreased when ringed seal ovulation rate was high. Polar bear δ15N and δ13C were linked to capture locations, which may reflect geographic gradients in stable isotopes within the Beaufort Sea. Climate indices were not related to polar bear δ15N and δ13C. Sea ice dynamics were related to polar bear δ13C, suggesting that the bears’ diets shift in response to environmental change. Overall, these results highlight the biological link between polar bears and ringed seals, as well as sea ice dynamics, and the importance of considering geographic location in stable isotope studies. KEY WORDS: Ursus maritimus · Polar bear · Beaufort Sea · Sea ice dynamics · Environmental change · Stable isotopes · Diet · Niche width Full text in pdf format Supplementary material PreviousCite this article as: Boucher N, Derocher AE, Richardson ES (2019) Variability in polar bear Ursus maritimus stable isotopes in relation to environmental change in the Canadian Beaufort Sea. Mar Ecol Prog Ser 630:215-225. https://doi.org/10.3354/meps13136 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 630. Online publication date: November 07, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".