A modelling-based perspective on the past, present, and future polychlorinated biphenyl contamination of the St. Lawrence beluga whale (<i>Delphinapterus leucas</i>) population
Bibliographic record
Abstract
Individual- and population-based models are presented that provide quantitative assessments of the accumulation of persistent organic pollutants over the lifetime of the beluga whale (Delphinapterus leucas) and consider all aspects of its life history. The models are used to examine the history of polychlorinated biphenyl (PCB) accumulation by the endangered St. Lawrence beluga population from 1950 to the present and to predict future trends based on likely contaminant loading scenarios. The hypothesis that migrating American eels (Anguilla rostrata) are a significant source of contaminants to the population is examined. The history of PCB exposure via the diet is reconstructed from existing data and from PCB profiles in dated sediment cores. The models adequately describe the effects of age, growth, sex, and reproductive activity on PCB concentrations in the beluga, and results show good agreement with observed concentrations when eels are included as 3% of the annual diet. PCB levels in the population appear to have peaked between 1967 and 1972. The model agrees with recent studies that have shown that PCB concentrations in the population are declining slowly.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".