Composition and temporal variation in the diet of beluga whales, derived from stable isotopes
Bibliographic record
Abstract
The diet of individuals within a species commonly differs among sex and age classes because of differences in energy requirements and physiological needs. Belugas Delphinapterus leucas show a high level of sexual habitat segregation and dimorphism that could result in differences in diet between the sexes. Here, we used stable isotopes of carbon ( 13 C) and nitrogen ( 15 N) from muscle and skin samples of 88 belugas, and likely prey species, to investigate how beluga diet in Cumberland Sound (Nunavut, Canada) varied between sexes, among age classes, and over time from 1982 to 2009. Based on linear mixed-effects models, older belugas had higher 13 C and 15 N than younger individuals of both sexes, suggesting that older individuals feed on more benthic, higher trophic-position prey than younger individuals. We also found a strong, decreasing trend in both 13 C and 15 N values over time, indicating either a temporal shift in beluga diet or an ecosystem-wide change in isotope values. Based on stable isotope mixing models performed on belugas sampled since 2000, both males and females fed primarily on Arctic cod Boreogadus saida and capelin Mallotus villosus. The latter is a recent invader to this ecosystem, which could explain the temporal shift in stable isotopes of the Cumberland Sound belugas.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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 teacher head, 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".