Exploring the depuration of metals in the green shore crab (Carcinus maenas): Studies with radiolabelled calcium, zinc, and nickel
Bibliographic record
Abstract
The depuration of newly accumulated metal from the crab Carcinus maenas (inter-moult stage) was studied, with a particular focus on the carapace, in light of recent findings that it is a major site for direct uptake and incorporation of Ca, Zn, and Ni from the external sea water. Crabs were exposed for 24 h to calcium ([Ca] = 389 mg L −1 or 9.7 mmol L −1 ), zinc ([Zn] = 82 μg L −1 or 1.25 μmol L −1 ), and nickel ([Ni] = 8.2 μg L −1 or 0.14 μmol L −1 ) with the addition of radio-labeled metal ( 45 Ca, 65 Zn, 63 Ni) in sea water (12 °C, 32 ppt), then transferred to clean sea water for ≥48 h. After 24 h of metal exposure, the carapace accounted for ≥85 % of the total body burden of all three newly accumulated metals. For Ca, depurations from the carapace and whole crab were negligible, though levels in soft tissues (gills, hemolymph, and muscle) fell quickly. In contrast, newly accumulated Zn levels in carapace and gills declined by ~60 % over 48 h, while muscle, hepatopancreas, and hemolymph burdens increased, reflecting shifts from gills and/or carapace to internal tissues. Newly accumulated Ni concentrations in the carapace and gills declined by ~50 % over 48 h, reaching >75 % loss by 10 days. As for Zn, Ni levels increased in the hemolymph and initially in the hepatopancreas, indicative of internal redistribution. Acute temperature increase (12 °C to 22 °C) had negligible effects on depuration rates (Q 10 values ~1.0). Depuration from the carapace was unchanged in recently euthanized crabs, or when the carapace was shielded with a membrane. We conclude that physicochemical processes are the rate-limiting steps for metal elimination from the carapace, and that metals newly incorporated in the carapace can leave only through the internal surface of the carapace; the external surface is not a depuration site. • We followed the depuration of newly accumulated metals in clean sea water for ≥48 h. • Ca was lost from all soft tissues, but not from the carapace. • Zn and Ni were lost mainly from carapace and gills (increase in other soft tissues). • Carapace metal loss occurs via internal route (carapace to hemolymph to gills). • Carapace metal loss occurs via passive physicochemical (not life-mediated) processes.
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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 | 0.000 | 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 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".