Under-ice microbial dimethylsulfoniopropionate metabolism during the melt period in the Canadian Arctic Archipelago
Bibliographic record
Abstract
This study reports on the temporal variations in algal and bacterial metabolism of dissolved dimethylsulfoniopropionate (DMSPd) in Arctic ice-covered waters in response to the release of organic matter (OM) from the sea ice and the onset of under-ice phytoplankton growth. Sampling took place between 21 May and 21 June 2012 at a station located in Resolute Passage. A snow and ice melt event was accompanied by an important release of OM and total DMSP from the bottom ice to the water column. This input of OM coincided with increases in DMSPd and DMSPd loss rate constant at the ice-water interface and, 2 days later, with increases in DMSPd and bacterial dimethylsulfide (DMS) yields from DMSPd at 0.5 m under the ice. The different microbial responses suggest that DMSPd-rich brines were released first, followed by the release of sympagic algae due to ice melt. In both cases, the changes in DMSPd metabolism resulted in an increase in gross DMS production from 0.15 to 1.9 nmol l -1 d -1 . The initiation of phytoplankton growth resulted in increases in bacterial abundance, DMSPd loss-rate constant and DMSP-sulfur assimilation. In contrast, DMS yield remained low during the onset of phytoplankton growth, indicating that bacteria used DMSP as a carbon and sulfur source. These results show that ice DMSPd can be rapidly (<1 d) and efficiently (up to 10%) converted into DMS by bacteria once released in surface water during melt events, a process that could contribute to DMS peaks measured at the ice edge.
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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 | 0.001 | 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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".