Does trophic position of the omnivorous signal crayfish (<i>Pacifastacus leniusculus</i>) in a stream food web vary with life history stage or density?
Bibliographic record
Abstract
Food mixing behavior of omnivorous consumers can be difficult to predict. We undertook an enclosure experiment to explore the effects of ontogenetic stage and density on food choices of the omnivorous signal crayfish, Pacifastacus leniusculus. Juvenile or adult crayfish were placed in in-stream enclosures for 6 weeks at three different densities. Gut and stable isotope analyses were used to determine the food sources utilized by these organisms. In addition, we analyzed the guts of both adult and juvenile crayfish from outside the enclosures to account for experimental effects. We found few differences in the gut contents between juvenile and adult crayfish from either inside or outside the enclosures, as the majority of food consumed by both ontogenetic stages and all densities was allochthonous detritus. Stable isotope results indicate that crayfish of both ontogenetic stages were relying primarily on detrital biofilms for nutrition, despite an additional laboratory experiment showing that growth would be far more rapid on invertebrates. The dietary choices made by P. leniusculus in its native environment seem to be primarily affected by factors other than the nutritional value of food sources, contrary to expectations that food mixing behavior of omnivores should be based on this factor alone.
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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 | 0.000 | 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 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".