Trophic position variability of European sardine by compound-specific stable isotope analyses
Bibliographic record
Abstract
The study of the trophic position (TP) of organisms is crucial to understand the trophodynamics of ecosystems. The European sardine from the western Mediterranean has been highly exploited during the last decades and has shown an important population decline. To determine the TP, we quantified seasonal nitrogen stable isotope (δ15N) values of compound-specific stable isotope analysis of amino acids (CSIA-AA), as well as bulk δ15N (SIA-bulk) values in muscle from three areas of the north-western Mediterranean. Our results highlight that, despite observing latitudinal changes in nitrogen SIA-bulk, the TP of sardine remains similar between sites. These results suggest that changes in nitrogen SIA-bulk are mainly driven by changes in the isotopic ratio of the baseline. Furthermore, the seasonal nitrogen variation in SIA-bulk is linked to differences in the isotopic baseline of the pelagic food web observed in the source AAs. Using CSIA-AA allowed us to decouple the variation in the baseline from the trophic variation producing robust TP estimates. Without using CSIA-AA, the interpretation of nitrogen SIA-bulk was hampered by the lack of a proper regional baseline of the primary producers.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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".