Osmorespiratory Compromise in Zebrafish ( <i>Danio rerio</i> ): Effects of Hypoxia and Acute Thermal Stress on Oxygen Consumption, Diffusive Water Flux, and Sodium Net Loss Rates
Bibliographic record
Abstract
The traditional thesis of the osmorespiratory compromise is that low branchial water and ion permeability would be traded off for increased O2 permeability at times of elevated O2 demand. However, there is growing evidence of independent regulation of these permeabilities in hypoxia-tolerant fish. Using 0.5-g zebrafish previously maintained under normoxia at 25°C, we investigated responses to acute temperature challenges (15°C or 35°C), acute hypoxia (15 min at 10% or 5% air saturation), as well as longer-term exposures to 10% hypoxia, on O2 consumption (MO2), diffusive water flux, and net sodium loss rates. Exposure to 35°C increased, and 15°C decreased all three rates, with diffusive water flux showing the lowest temperature sensitivity, and Na+ loss the greatest. Acute 10% and 5% hypoxia increased diffusive water flux and net Na+ loss, and it reduced MO2. All these responses reflected the traditional osmorespiratory compromise. However, during prolonged 10% hypoxia, MO2 recovered, diffusive water flux decreased below control levels, and Na+ loss rate remained elevated, even during posthypoxia recovery. Overall, zebrafish do not fit standard patterns previously seen in either hypoxia-tolerant or -intolerant fish but are clearly able to adjust the effective permeabilities of their gills to O2, water, and ions independently during acute temperature and hypoxia exposures.
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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 | 0.001 |
| 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".