Multiple stable isotopes identify sediment organic matter as the primary nutritional source to American brook lamprey larvae along a stream gradient
Bibliographic record
Abstract
Multiple stable isotope ratios (δ2H, δ13C, δ15N, and δ34S) of American brook lamprey (Lethenteron appendix) ammocoetes and their potential sources were measured along a stream gradient. Isotopic ratios were successful at differentiating three potential sources: terrestrial organic matter (TOM; upland plants), sediment organic matter (SOM; benthic organic material), and algae. Bayesian mixing models (MixSIAR) utilizing δ13C, δ15N, and δ34S estimated ammocoetes were highly reliant on SOM at all sites (>95%), but inclusion of δ2H increased the importance of both algae and model uncertainty. Ammocoete δ2H was more depleted than anticipated even after lipid extraction and after accounting for trophic water contributions, suggesting δ2H in consumer tissues (especially for long-lived animals) is still incompletely understood. Model sensitivity testing with trophic fractionation values did not substantially change the results. Regardless of the mixing model investigated, none indicated more algae in ammocoete diets in downstream rather than upstream sites, in contrast with expectations about river productivity. Stable isotopes suggest SOM, and not algae, is nutritionally most important to ammocoetes, even in downstream reaches of rivers.
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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 | 0.000 | 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) | 0.000 | 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".