Mercury concentrations in lake sturgeon from four river systems in Manitoba, Canada
Bibliographic record
Abstract
Lake sturgeon (Acipenser fulvescens) are large, long-lived fish, characteristics conducive to the bioaccumulation of mercury. This study measured total mercury (THg) in the axial musculature of 319 lake sturgeon captured between 2002 and 2022 from six river reaches on the Winnipeg, Nelson, Churchill, and Hayes Rivers in the province of Manitoba, Canada. Since the 1900s, all sampled rivers except the Hayes were affected by hydroelectric development, which can increase THg concentrations in fish for several decades following inundation. Concentrations of THg in lake sturgeon measuring 171-1,435 mm fork length ranged from less than the detection limit (0.005 ppm) to 0.698 ppm wet weight. Total mercury concentrations increased significantly with fish length for all waterbodies analyzed, except for the Hayes River, where the sample size and length range were small. Mean length-standardized THg concentrations ranged from 0.069-0.177 ppm and differed significantly between waterbodies. Concentrations were lowest where the majority of samples were collected from fish that had been hatchery-reared and stocked. A paucity of historical data precludes the isolation of effects of hydroelectric impoundment on THg levels in lake sturgeon, but concentrations are not particularly high in any of the waterbodies examined herein. Of the 35 lake sturgeon also analyzed for diet composition, 34 had identifiable gastrointestinal contents. Ten different prey taxa were identified, including fish. Chironomids dominated dietary numerical abundance. The number of taxa increased with fish length to include larger, and therefore potentially more, THg-rich organisms.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".