Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species
Bibliographic record
Abstract
It is commonly assumed that most (>95%) of the mercury (Hg) found in fish muscle is the toxic form, methylmercury (MeHg), due to its efficient assimilation and retention in biotic tissue. However, this assumption is largely based on studies examining the percentage of MeHg (%MeHg [the fraction of total Hg as MeHg]) in muscle from mostly large-bodied predatory fish; less is known about the %MeHg in smaller bodied individuals or those of different trophic guilds. The present study analyzed MeHg and total Hg concentrations in the muscle of 2 large-bodied piscivores (walleye and northern pike), one large-bodied benthivore (white sucker), and 2 small-bodied forage fish (sculpins and shiners) across a broad size range. We found substantially lower %MeHg than the commonly assumed 95% in several fish (e.g., 17 individuals had <70% MeHg). Muscle %MeHg significantly increased with size and age in all species except walleye, which had significantly higher %MeHg than pike or suckers, particularly in smaller and younger fish (e.g., 18-21% higher at 10 g; 5-11% higher at 500 g). Results of predictive modeling suggest that muscle %MeHg is higher in pelagic-feeding fish and those with lower lipid content, although model results varied significantly among species. According to our findings, total Hg measurement in muscle is not an appropriate proxy for MeHg in smaller fish from all species, an important consideration for future piscine Hg studies and monitoring. Environ Toxicol Chem 2018;37:2682-2691. © 2018 SETAC.
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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 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".