Tracking Overwintering Areas of Fish-Eating Birds to Identify Mercury Exposure
Bibliographic record
Abstract
Migration patterns are believed to greatly influence concentrations of contaminants in birds due to accumulation in spatially and temporally distinct ecosystems. Two species of fish-eating birds, the Double-crested Cormorant (Phalacrocorax auritus) and the Caspian Tern (Hydroprogne caspia) breeding in Lake Ontario were chosen to measure the impact of overwintering location on mercury concentrations ([Hg]). We characterized (1) overwintering areas using stable isotopes of hydrogen (δ(2)H) and band recoveries, and (2) overwintering habitats by combining information from stable isotopes of sulfur (δ(34)S), carbon (δ(13)C), nitrogen (δ(15)N), and δ(2)H in feathers grown during the winter. Overall, overwintering location had a significant effect on [Hg]. Both species showed high [Hg] in (13)C-rich habitats. In situ production of Hg (e.g., through sulfate reducing bacteria in sediments) and allochthonous import could explain high [Hg] in birds visiting (13)C-rich habitats. Higher [Hg] were found in birds with high δ(2)H, suggesting that Hg is more bioavailable in southern overwintering locations. Hotspot maps informed that higher [Hg] in birds were found at the limit of their southeastern overwintering range. Mercury concentrations in winter feathers were positively related to predicted spatial pattern of [Hg] in fish using the National Descriptive Model of Mercury in Fish (NDMMF) based on bird spatial assignment (using δ(2)H). This study indicates that the overwintering location greatly influences [Hg].
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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 | 0.001 | 0.001 |
| 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".