Hyperoxia acclimation and the aerobic response in red drum (Sciaenops ocellatus)
Bibliographic record
Abstract
Hyperoxia is supersaturation of oxygen beyond 100 % air saturation (~21 kPa) in aquatic environments. Hyperoxia promotes an oxygen diffusion gradient that greatly increases arterial and venous oxygen in the circulatory system of fish. Under these conditions fish can potentially upregulate mechanisms that benefit from supersaturation by increasing oxygen use and delivery. To test this, we acclimated the estuarine red drum ( Sciaenops ocellatus ) to three weeks of normoxic control (100 % air saturation, ~20.7 kPa) or hyperoxic treatment (150 % air saturation, ~32.5 kPa). We measured whole-animal metabolic rate in a cross design to assess aerobic scope and observed oxygen supply capacity, α o . Following recovery, fish were sampled for magnitude of the Root effect and mitochondrial respiration of cardiac tissue. Red drum acclimated to hyperoxia showed lower mean cell hemoglobin content, decreased methemoglobin, and a modest decrease in red blood cell pH. The Root effect, the pH sensitivity that limits carrying capacity, was measured to ascertain differences in O 2 delivery in the heart; however, we found no differences due to acclimation. Cardiac mitochondria respiration showed no difference between acclimations. Acclimation did not impact whole-animal metabolic rate. However, fish from both acclimations increased maximum metabolic rate when exhaustively exercised in hyperoxia, which subsequently increased aerobic scope. Measures of α calculated at maximum metabolic rate and at the critical oxygen tension (P crit ) showed that α was lower when calculated in hyperoxia than normoxia or at P crit . These data suggest that fish can benefit from hyperoxia in acute exposures, with subtle adjustments made in chronic hyperoxia. • Chronic hyperoxic acclimation lowered intracellular red blood cell pH and hematocrit. • Chronic hyperoxia did not impact whole-animal O 2 consumption. • Acute exposure to hyperoxia during exercise and recovery increased aerobic scope and maximum metabolic rate for all fish. • O 2 supply capacity was lower in all fish acutely exposed to hyperoxia. • Fish may make some adjustments in acute exposure, but the respiratory system is not plastic to benefit from supersaturated O 2 long-term.
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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".