Stoichiometric and growth responses of a freshwater filamentous green alga to varying nutrient supplies: slow and steady wins the race
Bibliographic record
Abstract
Summary We examined how the nutrient stoichiometry of the filamentous green alga, Mougeotia sp., is affected by the relative availability of dissolved nitrogen (N) and phosphorus (P). Using a bioassay experiment, we grew Mougeotia in medium having a range of dissolved N and P concentrations and N:P ratios (0.62 to 411 by mol). After growing Mougeotia in an environmental chamber for 17 days, we measured its carbon (C), N and P content (% of dry mass), molar C:N:P ratios, mass‐specific growth rate (MSGR, day−1), chlorophyll a concentration (Chl, μg L−1) and carbon:chlorophyll a (C:Chl) ratios. Due largely to variation in cellular %N and %P, Mougeotia C:N:P ratios varied considerably at the end of the experiment, with C:N ratios ranging from 6 to 41, C:P ratios ranging from 85 to 999 and N:P ratios ranging from 4 to 118. We found Mougeotia to be weakly homeostatic with respect to N:P content, with non‐homeostatic tendencies found for N content and P content. Despite the wide range of N and P concentrations in the medium at the start of the experiment, Mougeotia MSGR was relatively invariant. Nevertheless, high C:Chl ratios observed for N‐ and P‐limited Mougeotia largely matched those expected for algae experiencing nutrient‐limited growth. We further compared our experimental results with stoichiometric data for Mougeotia collected from the Kawartha Lakes in southern Ontario. The high C:P and N:P ratios found in field samples matched those of laboratory Mougeotia experiencing intense and sustained P limitation and are suggestive of severe P limitation of Mougeotia in Kawartha Lakes throughout the summer. The slow growth rates and flexible stoichiometry of this alga would enable it to continue growing even during periods of acute nutrient stress. Hence, future management and control of this nuisance alga may prove difficult if it is unlikely to respond strongly to reductions in external P loading and lower water column P concentrations.
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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 | 0.001 |
| 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 | 0.001 | 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".