Contamination of Mercury during the Wintering Period Influences Concentrations at Breeding Sites in Two Migratory Piscivorous Birds
Bibliographic record
Abstract
Many aquatic fish-eating birds migrate long distances and are exposed to different mercury concentrations ([Hg]) during their annual cycle. Here we examined the importance of migration on [Hg] in two colonial migratory fish-eating bird species. We determined temporal trends of [Hg] and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) during the annual cycle in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) breeding in Lake Ontario by a repeated sampling of breast feathers and blood from recaptured individuals. We found an effect of previous winter [Hg], species, sex, and location to explain variations of Hg at breeding sites. This suggests Hg carryover from winter to summer periods and that variations of [Hg] in the summer are partially explained by [Hg] in the winter. Carryover of Hg among seasons and slow changes in [Hg] over time were found especially for individuals in high winter exposure groups, suggesting a slow depuration rate and a fast uptake rate for both species. In contrast, stable isotope values rapidly switched to reach equilibrium at a similar midpoint regardless of winter habitat or diet suggesting minimal carryover of isotopic signatures. The potential of Hg carryover from wintering sites indicates that Hg concentrations in birds at a given time may be influenced by previous exposure from distant locations.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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".