Short- and long-term effects of irradiance and CO<sub>2</sub> availability on carbon fixation by two marine diatoms
Bibliographic record
Abstract
Unbuffered and nutrient-replete dilute batch cultures of Skeletonema costatum Cleve and Phaeodactylum tricornutum Bohlin were grown at high and low CO2 availability conditions and two incident irradiances, 150 and 30 µmol photons·m2·s1. Long-term combined effects of such light and CO2 availability conditions on carbon fixation rates of both diatoms were compared. At saturating light, P. tricornutum showed higher photosynthetic rates than S. costatum at both CO2 conditions. However, under subsaturating light, carbon fixation rates of P. tricornutum were higher than observed for S. costatum only at low CO2. Skeletonema costatum showed a strong reduction in photosynthetic rates only when both resources, irradiance and CO2, were low. Short-term alterations of light and CO2 availability on carbon fixation showed that the response of S. costatum differed considerably from long-term trends: the short-term reduction in CO2 availability at both light levels resulted in a considerable decrease in the maximum photosynthetic rates. This effect was much less noticeable in P. tricornutum. The results show that, at saturating light, both diatoms maintain maximum photosynthetic rates under low CO2 levels, but only P. tricornutum is well adapted to rapid changes in this resource. This capacity of adaptation seems to be light dependent, since light limitation altered the responses of both diatoms to low CO2 availability conditions.Key words: CO2, 14C fixation, irradiance, Phaeodactylum tricornutum, Skeletonema costatum.
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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) | 0.001 | 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".