The interactive effects of calcium concentration and temperature on the survival and reproduction of <i>Daphnia pulex</i> at high and low food concentrations
Bibliographic record
Abstract
We reared Daphnia pulex in a fully defined medium at seven calcium (Ca) concentrations (0.1, 0.5, 1, 1.5, 2, 5, and 10 mg Ca L −1 ), two mixed algal densities (high food: 30 mg chlorophyll a L −1 and low food: 3 mg Chl a L −1 ), and four temperatures (20&ordm;C, 24&ordm;C, 28&ordm;C, and 32&ordm;C) in a fully factorial design. The minimum Ca concentration required for the survival and reproduction of D. pulex was between 0.1 and 0.5 mg Ca L −1 . Daphniids reared at 0.1 mg Ca L −1 lived no longer than 10 d and did not reproduce. Although offspring were produced at 0.5 mg Ca L −1 and above, reproduction was reduced below 1.5 mg Ca L −1 due to delays in maturity and reductions in both the brood size and number of broods produced within the 15 d of the experiment. As a result, the intrinsic rate of natural increase, r, decreased dramatically between 1.5 and 1 mg Ca L −1 , and was undefined at 0.1 mg Ca L −1 . Higher temperatures and reduced algal biomass enhanced the susceptibility of D. pulex to low Ca concentrations by raising the reproductive threshold to 1.5 mg Ca L −1 . Thermal stress at 32&ordm;C was so great that daphniids lived no longer than 5 d and did not reproduce. Hence, r was undefined at 32&ordm;C. In order to sustain D. pulex populations and potentially other Ca‐sensitive daphniids, fresh waters must maintain a Ca concentration of at least 0.5 mg Ca L −1 , although concentrations as high as 1.5 mg Ca L −1 may be required for daphniids to withstand the concurrent reductions in algal biomass and rising water temperatures that are now commonplace on the south‐central Canadian Shield.
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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 | 0.001 |
| 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".