The evolution and termination of an iron-induced mesoscale bloom in the northeast subarctic Pacific
Bibliographic record
Abstract
We initiated and mapped a diatom bloom in the northeast subarctic Pacific by concurrently adding dissolved iron and the tracer sulfur hexafluoride to a mesoscale patch of high-nitrate, low-chlorophyll waters. The bloom was dominated by pennate diatoms and was monitored for 25 d, which was sufficiently long to observe the evolution and termination of the bloom and most of the decline phase. Fast repetition–rate fluorometry indicated that the diatoms were iron-replete until day 12, followed by a 4–5-d transition to iron limitation. This transition period was characterized by relatively high rates of algal growth and nutrient uptake, which pointed to diatoms using intracellularly stored iron. By days 16–17, the bloom was probably limited simultaneously by both iron and silicic acid supply, because low silicic acid concentrations were evident. Modeling simulations, using data from our study, provided an estimate of the critical threshold for algal aggregation. Observed diatom abundances during the bloom exceeded this threshold between days 13 and 17. Mass sedimentation of diatoms and diatom aggregates was recorded in surface-tethered free-drifting sediment traps at 50 m in depth on day 21. Although the termination of the bloom was probably controlled by the availability of both iron and silicic acid, we cannot rule out the role of algal aggregation. The bloom decline was likely triggered by the onset of mass sedimentation. During our study, evidence of both diatom species succession and species-specific aggregation point to important links between algal nutrient stress and the initiation of algal aggregation.
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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) | 0.000 | 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 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".