Isotopic turnover in aquatic predators: quantifying the exploitation of migratory prey
Bibliographic record
Abstract
In the tidal freshwaters of Virginia, U.S.A., the blue catfish (Ictalurus furcatus), an introduced piscivore, derives a significant proportion of its nutrition from spawning anadromous fish (genus Alosa, including blueback herring (A. aestivalis), American shad (A. sapidissima), and alewife (A. pseudoharengus)). Because the Alosa are not continually available to I. furcatus, there is an isotopic turnover, defined as change in isotope composition due to growth and metabolic tissue replacement, in I. furcatus tissues associated with the diet switch from freshwater to anadromous fishes. However, isotopic turnover rates for ictalurid fish are unknown. This study determined the maximum isotopic turnover rate of channel catfish (Ictalurus punctatus) tissues and compared this maximum rate with that of I. furcatus captured in the field over the 3-month Alosa spawning run. Maximum turnover rates for δ 13 C were 0.014 and 0.017 per day in muscle and blood. For δ 34 S, rates were 0.017 and 0.020 per day in muscle and blood, respectively. Isotopic turnover of muscle carbon reflected growth rate, but sulfur did not match growth as well. Ictalurus furcatus captured in the field showed no enrichment during the Alosa spawning run owing to slow turnover and variable diet. In aquatic ecosystems that have migrating prey, exploitation by predators may be underestimated using isotopes because of slow tissue turnover.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| 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 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".