ARE CURRENT CONTAMINANT CONCENTRATIONS IN EGGS AND BREEDING FEMALE LESSER SCAUP OF CONCERN?
Bibliographic record
Abstract
One of the proposed explanations for the recent continental decline in Lesser Scaup (Aythya affinis) populations is that females experience lower survival or reproduction resulting from exposure to contaminants in their diet of exotic bivalves during migration and over winter. In 1999, we collected eggs and females from five sites in the boreal forest of Canada and Alaska and four sites in Canadian parkland. We analyzed eggs from 60 clutches and ten nesting females for toxic metals, selenium, 19 pesticides and other organochlorines, and 43 polychlorinated biphenyl (PCB) congeners. The highest organochlorine concentration we measured was 1.5 μg g−1 ww of DDE in eggs. The highest mercury concentration was 1.8 μg g−1 dw in liver. The highest cadmium concentration was 6.2 μg g−1 dw in kidney. The highest selenium concentrations measured were 1.6 μg g−1 ww in eggs, and 5.3 μg g−1 dw in liver. All are well below thresholds known to cause embryotoxic and other effects in other bird species. Though sample sizes were small and did not include the entire breeding range or nonbreeders, our results provide no evidence to support the hypothesis of contaminant-induced effects on egg hatchability and female health. However, recently published concentrations of selenium in zebra mussels (Dreissena polymorpha) and Asian clams (Potamocorbula amurensis), predominant foods on staging areas, are sufficient to induce other sublethal effects, and possibly mortality if eaten by scaup for extended periods. ¿Son Preocupantes las Concentraciones Actuales de Contaminantes en los Huevos y Hembras Reproductivas de Aythya affinis? Resumen. Uno de los argumentos propuestos para explicar la disminución reciente de las poblaciones continentales de Aythya affinis es que como consecuencia de la exposición a contaminantes presentes en su dieta de bivalvos exóticos durante la migración y el invierno, la supervivencia o reproducción de las hembras es reducida. En 1999, colectamos huevos y hembras en cinco sitios ubicados en bosques boreales de Canada y Alaska y en cuatro sitios en parques canadienses. Analizamos los metales tóxicos, selenio, 19 pesticidas y otros organoclorados y 43 congéneres de bifenil policlorado (PCB). La concentración más alta de organoclorados que medimos fue de 1.5 μg g−1 (peso fresco) de DDE, en huevos. La concentración más alta de mercurio fue 1.8 μg g−1 (peso seco), en hígado. La concentración más alta de cadmio fue 6.2 μg g−1 (peso seco), en riñón. Las concentraciones de selenio más altas fueron 1.6 μg g−1 (peso fresco) en huevos y 5.3 μg g−1 (peso seco) en hígado. Todas estas medidas están por debajo de los niveles que causan efectos embriotó xicos y de otros tipos en otras especies de aves. Aunque los tamaños muestrales fueron pequeños y no incluyeron todo el rango de distribución reproductivo ni aves que no se estaban reproduciendo, nuestros resultados no proveen evidencia para apoyar la hipótesis de que existen efectos inducidos por los contaminantes sobre la capacidad de eclosionar de los huevos y la salud de las hembras. Sin embargo, las concentraciones de selenio en los bivalvos Dreissena polymorpha y Potamocorbula amurensis, alimentos predominantes en áreas de escala migratoria, son suficientes para inducir otros efectos no letales y posiblemente la muerte si son consumidos por A. affinis por períodos prolongados.
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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 | 0.000 | 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 | 0.000 | 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) | 0.000 | 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".