The transformation and fate of sub‐Arctic microphytobenthos carbon revealed through <sup>13</sup> C‐labeling
Bibliographic record
Abstract
Microphytobenthos (MPB) at higher latitudes has been poorly studied. This study used pulse-chase 13C-labeling to investigate the production, processing, and fate of MPB-derived carbon (MPB-C) in sub-Arctic intertidal sediments over 31 d. Gross primary production (2.1 mmol C m−2 h−1 ± 0.4 mmol C m−2 h−1) was comparable to that reported for temperate regions. Some of the 13C fixed by sub-Arctic MPB was rapidly (within 0.5 d) transferred to deeper sediments (below 2 cm), but most was retained within surface sediments (>70.2% of the 13C present at any time during the study). At any time, MPB accounted for ≥ 49.8% of this 13C. The 13C content of sediment organic carbon declined over time, but > 31% of the 13C fixed within the first tidal cycle remained after 31 d, suggesting that sub-Arctic MPB may contribute to coastal carbon retention during the productive season. Over 21 d, 10.6% of the fixed 13C was removed via DIC fluxes and 0.3% via DOC fluxes from inundated sediment, and 0.6% as CO2 from exposed sediment. The greatest loss of 13C (38.2%) was via unmeasured pathways, including resuspension and/or removal by mobile consumers. The rates of MPB-C production and the relative importance of the pathways for MPB-C loss were similar to that observed for comparable lower latitude sediments, demonstrating that MPB at higher latitudes are not necessarily distinct from MPB at lower latitudes and probably play a similarly important role in ecosystem functioning. Apparently, local environmental conditions are more important than climate differences for determining the processing and fate of MPB-C.
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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) | 0.000 | 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".