Oxygen consumption from air and water, ammonia and urea‐ <scp>N</scp> excretion, and <scp>Na</scp> <sup>+</sup> fluxes during progressive aquatic hypoxia in <scp>Amazonian</scp> armoured catfish <i>Pterygoplichthys gibbiceps</i> and <i>Pterygoplichthys pardalis</i>
Bibliographic record
Abstract
Abstract The Amazonian loricariid fish Pterygoplichthys gibbiceps, from the Rio Negro, and Pterygoplichthys pardalis, from the Rio Solimões, are facultative air‐breathers that can use the stomach as an air‐breathing organ. Measurement of oxygen uptake under progressive aquatic hypoxia revealed a relatively high hypoxia resistance of both species. In both species, air‐breathing was initiated at aquatic PO 2 values below 3 kPa. In hypoxia, aerial oxygen uptake was dominant, but in P. gibbiceps total oxygen uptake was reduced to 55 ± 5% of the normoxic values, and in P. pardalis to only 43 ± 4% of the normoxic value. P. pardalis took a greater percentage of its total O 2 consumption from air (92 ± 2%) than did P. gibbiceps (85 ± 3%). Air‐breath volume increased with body mass in P. gibbiceps , whereas in P. pardalis air‐breathing frequency increased with body mass. The minimal breath volume required to account for aerial oxygen uptake was calculated as 24.9 ± 2.1 mL*kg −1 for P. pardalis, and 17.3 ± 1.1 mL*kg −1 for P. gibbiceps . In both species, ammonia and urea‐N excretion were not significantly modified under hypoxic conditions, and urea‐N excretion contributed a relatively high percentage (23%) to total nitrogen excretion. Measurement of unidirectional and net Na + flux rates during normoxia, hypoxia and subsequent normoxic recovery in P. gibbiceps revealed a significant decrease in Na + influx rate under hypoxic conditions, followed by a significant increase during recovery compared to the control period, with no changes in net Na + balance. The data suggest that a reduction in energy‐consuming processes may contribute to the observed hypoxia resistance.
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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".