What do harp seals eat? Comparing diet composition from different compartments of the digestive tract with diets estimated from stable-isotope ratios
Bibliographic record
Abstract
This study compared diet reconstructed from different compartments of the digestive tract of harp seals (Pagophilus groenlandicus (Erxleben, 1777)) with the diet estimated using stable carbon and stable nitrogen isotope ratios in mixing models. Diet composition in 18 feeding harp seals (mean age = 2.4 years, SD = 1.8 years, range = 0–6 years) was determined using traditional methods of hard-part identification and reconstruction, and stable carbon and stable nitrogen isotope ratios. Diet composition consisted of 68.8% (SD = 8.7%) and 69.6% (SD = 11.6%) by mass of invertebrates or 65.0% (SD = 8.8%) and 66.5% (SD = 11.8%) by energy of invertebrates for the stomach and small-intestine compartments, respectively. Reconstructed diets using material recovered from the large-intestine contents suggested a diet of 43.1% (SD = 12.2%) and 38.0% (SD = 11.9%) invertebrates using mass and energy, respectively. Stable carbon and stable nitrogen isotope ratios determined for the same individual harp seals suggested a diet consisting of approximately 66.1% (SD = 117.4) invertebrates, indicating that diet reconstructions based on hard parts from stomachs are likely to be more representative than reconstructions from large-intestine contents. In species that feed on a combination of vertebrates and invertebrates, the use of faecal material to reconstruct diet composition will likely underestimate the importance of invertebrates in the diet.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".