INORGANIC CARBON UTILIZATION BY ROSS SEA PHYTOPLANKTON ACROSS NATURAL AND EXPERIMENTAL CO<sub>2</sub> GRADIENTS<sup>1</sup>
Bibliographic record
Abstract
We present results from a field study of inorganic carbon (C) acquisition by Ross Sea phytoplankton during Phaeocystis ‐dominated early season blooms. Isotope disequilibrium experiments revealed that HCO 3 − was the primary inorganic C source for photosynthesis in all phytoplankton assemblages. From these experiments, we also derived relative enhancement factors for HCO 3 − /CO 2 interconversion as a measure of extracellular carbonic anhydrase activity (eCA). The enhancement factors ranged from 1.0 (no apparent eCA activity) to 6.4, with an overall mean of 2.9. Additional eCA measurements, made using membrane inlet mass spectrometry (MIMS), yielded activities ranging from 2.4 to 6.9 U · [μg chl a ] −1 (mean 4.1). Measurements of short‐term C‐fixation parameters revealed saturation kinetics with respect to external inorganic carbon, with a mean half‐saturation constant for inorganic carbon uptake ( K 1/2 ) of ∼380 μM. Comparison of our early springtime results with published data from late‐season Ross Sea assemblages showed that neither HCO 3 − utilization nor eCA activity was significantly correlated to ambient CO 2 levels or phytoplankton taxonomic composition. We did, however, observe a strong negative relationship between surface water pCO 2 and short‐term 14 C‐fixation rates for the early season survey. Direct incubation experiments showed no statistically significant effects of pCO 2 (10 to 80 Pa) on relative HCO 3 − utilization or eCA activity. Our results provide insight into the seasonal regulation of C uptake by Ross Sea phytoplankton across a range of pCO 2 and phytoplankton taxonomic composition.
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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".