Organochlorine Contamination and Physiological Responses in Nestling Tree Swallows in Point Pelee National
Bibliographic record
Abstract
Abstract. Point Pelee National Park in southwestern Ontario, Canada—a major migratory route and vital breeding area for many birds—has localized areas of organochlorine (OC) contamination from the 1950s and 1960s. During 2002, we investigated the effect of tissue OC contaminant levels on the physiology and growth of nestling tree swallows (Tachycineta bicolor). Polychlorinated biphenyl (PCB) contamination in the nestlings positively correlated with hepatic ethoxy-, benzyl-oxy-, and pentoxyresorufin-o-dealkylase enzyme activities and liver size. Despite detectable physiologic changes associated with body burdens of PCBs, reproductive success of breeding pairs was not affected. Hatching date was negatively correlated with PCB levels, alkoxyresorufin-O-dealkylase (alkROD) activities, liver size, and serum protein levels. alkROD activ-ities were largely dependent on hatching date because insect prey contaminated with PCBs were only abundant during a limited period of time during the breeding season. Point Pelee National Park (PPNP) in southwestern Ontario, Canada is an important migratory route and vital breeding area for many birds. Within the park boundaries there are localized areas of organochlorine (OC) contamination from agrochem-icals used during the 1950s and 1960s (OConnor Associates Environmental 2001). OC contamination in the park was first recognized when high residues were detected in northern spring peepers (Psedacris crucifer) (Russell et al. 1995), but the impact on other resident species was not explored. During 2001 and 2002, the distribution of persistent contaminants in the food web was tracked using the tree swallow (Tachycineta bicolor) as a bioindicator (Smits et al. 2004). Tree swallows have been widely studied to document the biologic effects of anthropogenically imposed environmental stress (McCarty 2001; Custer et al. 2001a; Smits et al. 2000;
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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".