Isotopic reconstruction of marine food webs using cephalopod beaks: new insight from captively raised <i>Sepia officinalis</i>
Bibliographic record
Abstract
Cephalopod beaks are a valuable source of material for stable isotope analysis to reconstruct the feeding ecology of cephalopods and their predators. We conducted a controlled captive-rearing experiment on the cuttlefish Sepia officinalis L., 1758 to 10 months of age. During the first and second months of life, animals were fed mysids ( Mysidopsis sp.) and shrimp ( Palaemonetes pugio Holthuis, 1949), but after 2 months, they were fed a homogeneous diet of shrimp ( Farfantepenaeus aztecus (Ives, 1891) and Litopenaeus setiferus (L., 1767)) until sampling. Soft tissues such as buccal mass, arm, and mantle were enriched in 15 N over the shrimp diet by about 3.3‰, with little change in 13 C, a result in keeping with previous findings for other marine predators. However, beaks showed little isotopic enrichment over the diets at the time of beak formation, with the beak rostral tips representing the neonatal diet and the remaining beak material representing the adult (shrimp) diet. Additionally, for four wild cephalopod species ( Todaropsis eblanae (Ball, 1841), Illex coindetii (Verany, 1839), Loligo vulgaris (Lamarck, 1798), and S. officinalis) obtained commercially in France, we measured δ 13 C and δ 15 N values in lower beaks and soft tissues. Similar to the results of our captive study, soft tissues were consistently enriched in 15 N over beaks by an average of 4.8‰ (range 3.9‰–6.1‰) but were slightly depleted in 13 C by 0.8‰ (0.7‰–1.2‰). The isotopic measurement of cephalopod beaks can thus be used to directly trace the isotopic composition of cephalopod diets and will be a powerful tool in the reconstruction of higher-trophic-level predators of cephalopods, since beaks are often the only material remaining for analysis from field samples.
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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 | 0.000 |
| 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 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".