Differential response of marine populations to climate forcing
Bibliographic record
Abstract
In searching for causes of fluctuations in marine populations, investigators often assume that populations respond on the same time scale as the environmental forcing period, but this may not hold true. Here we show how the response of populations to variable recruitment changes with the degree of overcompensation using models of two species with similar age structure but different density-dependent recruitment, chinook salmon (Oncorhynchus tshawytscha) and Dungeness crab (Cancer magister). For compensatory density dependence, as in chinook salmon, variability in recruitment tends to follow the period in environmental variability over all time scales. For overcompensatory density dependence, as in Dungeness crab, variability in recruitment follows the environmental variability only for periods much greater than the maximum age of the population. For periods in environmental variability less than the maximum age, the dominant period of the population response is slightly larger than the length of the age structure. Here, strong overcompensatory recruitment acts to filter out potentially good recruitment years, resulting in dominant periodicities slightly larger than the length of the age structure. These mechanisms appear to explain the differences between observed spectra of Dungeness crab and chinook salmon.
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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 | 0.001 | 0.004 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".