Arctic phytoplankton spring bloom diversity across the marginal ice zone in Baffin Bay
Bibliographic record
Abstract
Abstract Phytoplankton under-ice blooms have been recently recognized as an important Arctic phenomenon for global primary production and biogeochemical cycling. Drastic sea-ice decline in both extension and thickness enables the development of early blooms, sometimes hundreds of kilometers beneath the pack ice. Baffin Bay is a semi-enclosed sea where Arctic and North Atlantic water masses interact. It is totally covered by sea-ice by March and ice-free by August/September. In the present work, we investigated the phytoplankton community structure across the marginal ice zone between the ice-free, Atlantic-influenced, east and the ice-covered, Arctic-influenced, west Baffin Bay using 18S rRNA high-throughput amplicon sequencing, flow cytometry cell counting and numerous environmental and biological data collected and compiled in the scope of the Green Edge project. Sampling was performed during June-July 2016 in a total of 16 stations with around 6 depths each. Stations were clustered into “Under Ice” (UI), “Marginal Ice Zone” (MIZ) and “Open Water” (OW) on the basis of its sea ice cover upon sampling. Phytoplankton community structure was analyzed by 18S rRNA metabarcoding with the microdiversity approach. The UI sector was characterized by a shallow nitracline, high pico-phytoplankton abundance and a shared dominance between Micromonas and Phaeocystis in the 0.2-3 µ m size fraction, as well as an increased contribution of Cryptophyceae and non-diatom Ochrophyta in the 3-20 µ m size fraction. Several amplicon sequence variants (ASVs) were flagged as indicator for the UI+MIZ sector group, including known ice-associated taxa such as the diatoms Melosira arctica and Pseudo-nitzschia seriata , but also specific ASVs assigned to the green alga Micromonas polaris and the cryptophyte Falcomonas daucoides , the silicoflagellate Dictyocha speculum , one member of the uncultivated MOCH-2 group, and a Pterosperma sp. (green algae) rarely seen in other metabarcoding datasets, including from the Arctic. The OW sector harbored a community adapted to a nutrient-depleted/high light environment, with a significant contribution of the haptophyte Phaeocystis pouchetii and big centric diatoms, including several Thalassiosira species.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".