Shifts in elemental composition, methylmercury content and δ<sup>15</sup>N ratio during growth of a High Arctic copepod
Bibliographic record
Abstract
Summary 1. We examined how ontogenetic development in a calanoid copepod from the High Arctic, Limnocalanus macrurus , influenced its elemental composition (carbon, nitrogen, phosphorus), methylmercury (MeHg) content and stable nitrogen and carbon isotope ratios in populations from nine lakes. 2. Population structure explained 33–83% of among‐lake variation in the C, N and P composition of the biomass. Biomass dominated by early‐stage copepodites had a greater P content, which declined in more mature populations, as indicated by significant changes in % P and the molar N/P ratio. Carbon and lipid contents increased with the proportion of adult biomass. Copepod populations sampled in warmer waters had a greater proportion of adult biomass, and water temperature was the most significant environmental variable explaining elemental composition. 3. A δ 15 N enrichment of 3.3 ± 1.0‰ was associated with copepodite development. Gut contents of L. macrurus showed no evidence of animal (invertebrate) prey, indicating no change in trophic position. 4. Unexpectedly, MeHg concentration was negatively correlated with the proportion of adult biomass. However, this trend was not significant after correcting MeHg concentration to non‐lipid dry mass, suggesting a lipid dilution effect in more mature copepods. Lake surface area, rather than ontogeny, best explained MeHg concentrations in L. macrurus . 5. Ontogenetic influences on chemical constituents of this common Arctic copepod, particularly δ 15 N ratios and uncorrected MeHg concentrations, highlight the relevance of developmental processes for studies of food webs and mercury in species‐poor High Arctic lakes.
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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) | 0.001 | 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 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".