Mercury contamination of an introduced generalist fish of intermediate trophic level
Bibliographic record
Abstract
Abstract Mercury contamination is a global issue because mercury concentrations in aquatic systems are influenced by both natural and anthropogenic pathways, including the burning of fossil fuels and flooding during hydroelectric development. Mercury biomagnifies in aquatic ecosystems, leading to higher concentrations in piscivore fishes than those at lower trophic levels. Here, liver and muscle total mercury (THg) concentrations in black crappie Pomoxis nigromaculatus from three lakes in southeastern Manitoba, Canada were related to age, morphology and physiological traits to better understand the dynamics of mercury accumulation in an introduced generalist fish species. Black crappie liver and muscle samples from Big Whiteshell Lake (relatively large lake, 17.5 km 2 ; n=30), Caddy Lake (small lake surrounded by wetlands, 3.1 km 2 ; n=42) and Lac du Bonnet (river widening influenced by hydroelectric dams, 84.0 km 2 ; n=29) were analyzed for THg content. These THg concentrations were then compared to black crappie mercury concentrations in other Canadian water bodies to assess within species relative contamination levels, as well as to mercury concentrations in other freshwater fishes to examine biomagnification. Age and size had strong positive correlations (r > 0.60) with muscle mercury concentrations. No evidence of acute point source contamination was found in the study area when compared to black crappie muscle mercury concentrations in other water bodies, and tissue THg concentration was not correlated with a reduction in gonadosomatic index (GSI) or hepatosomatic index (HSI). Analysis of liver THg in addition to muscle THg revealed the possible impacts of seasonal and ontogenetic differences in diet on exposure. Furthermore, THg analysis of liver and muscle tissue showed how generalist foraging techniques of black crappie may curb the progressively greater mercury exposure and resultant physiological consequences expected from ontogenetic diet shifts from invertebrates to fishes. Although there appeared to be temporally varied levels of mercury exposure (i.e., liver THg) by sex, there was no sex effect observed in long-term accumulation in the muscle. Flood risk is believed to be a key driver of differences in black crappie THg concentrations between lakes in the region. Black crappie bioaccumulated less mercury at age than primary piscivore species in the region. These results will help foster a better understanding of mercury biomagnification in boreal shield lakes within a region impacted by legacy mercury.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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".