Nitrogen excretion and oxygen consumption under severe hypoxia in <scp>s</scp> iluriform fishes from the <scp>A</scp> mazon
Bibliographic record
Abstract
Abstract Siluriform fishes collected from the Rio Negro and Rio Solimões proved to be highly resistant to aquatic hypoxia. In all four species analysed in this study, aquatic oxygen consumption significantly decreased from normoxic levels at water PO 2 values near 1 kPa. Air‐breathing activity was observed only in Sturisoma sp. (Rio Negro). In this species, under severe hypoxia, oxygen uptake from the air dominated, but total oxygen uptake was significantly lower than that under normoxic conditions. In Anadoras weddellii (Rio Solimões), aquatic surface respiration was detected. However, the other species ( Tympanopleura atronasus and three members of the family of Sternopygidae; Rio Solimões) showed no attempt to supplement aquatic oxygen uptake, even under severe hypoxia. In all species tested, neither ammonia nor urea‐N excretion was affected by the decreasing water PO 2 . At the lowest water PO 2 levels, the reduction in total oxygen uptake in the face of unchanged nitrogenous waste excretion resulted in extraordinary high nitrogen quotient (NQ) ratios. In normoxia, NQ ratios ranged from 0.16 to 0.34. Urea‐N excretion contributed between 19% and 28% to total nitrogen excretion and appeared to be unrelated to natural diet as indicated by the gut length‐to‐fork length ratio or to plasma urea‐N levels. Overall, our data underline the quantitative importance of urea‐N for nitrogen excretion in siluriform fishes.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".