Evidence of phosphorus‐limited individual and population growth of <i>Daphnia</i> in a Canadian Shield lake
Bibliographic record
Abstract
We performed bag experiments in a Canadian Shield lake with generally high seston (suspended food particles mainly composed of algae) carbon (C):phosphorus (P) ratios, and investigated the responses of individual and population growth of herbivorous Daphnia dentifera on their abundance with (+P) and without (−P) a phosphorus enrichment to lake water. In both treatments, increased abundance of D. dentifera reduced seston C concentration and was accompanied by decreases in population and individual growth rates. However, P‐enrichment increased seston P concentration and then reduced seston C:P ratio from 400–700 to ca 100 (by atoms). As a result, both individual and population growth rates were significantly higher in the +P treatment at all animal abundances even though seston C concentrations were similar between the treatments. The magnitude of the growth enhancement by the P‐enrichment was independent of animal abundance. Stepwise regression analyses revealed that 71 and 90% of the variance in the population and individual growth rates, respectively, were explained by seston C and P concentrations, and that the contribution of the seston P concentration was roughly the same as that of seston C. Such joint effects of seston C and P indicate that food quality (P content) as well as food quantity (C concentration) can influence Daphnia not only at the level of individual growth but also at the level of population dynamics in P‐limited lakes. Our results thus strongly corroborate the hypothesis that the population development of a key herbivore Daphnia in P‐limited Canadian Shield lakes is inhibited by the direct effects of P‐limited food on individual growth, which weaken the strength of trophic cascading interactions starting from piscivorous fish through planktivorous fish and zooplankton to algae.
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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) | 0.001 | 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 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".