Stable isotope analysis of ancient and modern gentoo penguin egg membrane and the krill surplus hypothesis in Antarctica
Why this work is in the frame
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Bibliographic record
Abstract
Abstract The ‘krill surplus’ hypothesis in Antarctica posits that the historic depletion of krill-eating whales and seals in the 18–20th centuries provided a surplus of krill in the Southern Ocean that benefited penguins. A previous study which examined stable isotopes in ancient and modern tissues of Adélie penguin ( Pygoscelis adeliae ) provides support for this hypothesis. Specifically, a significant decrease in δ 13 C and δ 15 N values occurred in modern versus ancient tissues from an apparent dietary shift from fish to krill associated with the purported krill surplus. Here, we present new data on gentoo penguin ( Pygoscelis papua ) tissues from active and abandoned colonies at three locations in the Antarctic Peninsula. We found an overall, but weak, decrease in modern versus fossil δ 15 N and δ 13 C values of gentoo penguin egg membrane with considerable variation across three breeding sites. Dietary mixing models suggest that shifts between fish and krill in gentoo penguins were likely not as strong as those previously observed in Adélie penguins. This weaker signal probably results from the greater reliance on fish in their diets, past and present, though we cannot rule out declines in primary productivity or other ecosystem shifts which also could account for declines in δ 13 C and δ 15 N values.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.004 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 it