Striped catfish (<i>Pangasianodon hypophthalmus</i>) use air‐breathing and aquatic surface respiration when exposed to severe aquatic hypercarbia
Bibliographic record
Abstract
Abstract We investigated the extent to which the facultative air‐breathing fish, the striped catfish ( Pangasianodon hypophthalmus ), uses air‐breathing to cope with aquatic hypercarbia, and how air‐breathing is influenced by the experimental exposure protocol and level of hypercarbia. We exposed individuals to severe aquatic hypercarbia (up to P w CO 2 = 81 mmHg) using step‐wise and progressive exposure protocols while measuring gill ventilation rate, heart rate, mean arterial blood pressure, and air‐breathing frequency, as well as arterial blood pH and PCO 2 . We confirm that P. hypophthalmus is tolerant of hypercarbia. Under both protocols gill ventilation rate, heart rate, and mean arterial blood pressure were maintained near control levels even at very high CO 2 levels. We observed a marked amount of individual variation in the PwCO 2 at which air‐breathing was elicited, with some individuals not responding at all. The experimental protocol also influenced the onset of air‐breathing. Air‐breathing began at lower P w CO 2 in the step‐wise protocol (23 ± 4.1 mmHg) compared with the progressive protocol (46 ± 7.8 mmHg). Air‐breathing was often followed by aquatic surface respiration, at higher PCO 2 (71 ± 5.2 mmHg) levels. On average, the blood PCO 2 was approximately 43% lower (46 ± 2.5 mmHg) than water P w CO 2 (~81 mmHg) at our highest tested CO 2 level. While this suggests that aerial CO 2 elimination is an effective, and perhaps critical, respiratory strategy used by P. hypophthalmus to cope with severe hypercarbia, this observation may also be explained by a long lag time required for equilibration.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.001 | 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".