Water pH alters acid-base compensatory responses in white sturgeon (Acipenser transmontanus) exposed to modest and severe environmental hypercapnia
Bibliographic record
Abstract
Elevated CO 2 (hypercapnia) in fishes induces a respiratory acidosis, which is compensated by branchial acid-base relevant ion transfer. This organismal compensation is hypothesized to be affected by water pH, but assessing this effect is difficult when examining fish species (e.g., rainbow trout Oncorhynchus mykiss , Japanese flounder, Paralichthys olivaceus ) that rely on extracellular pH regulation (pHe) to drive recovery as when it fails, mortality may occur quickly. Examining fishes that both perform pHe compensation, but do not require it for survival due to preferential intracellular pH (pH i ) regulation (PPR) such as does the white sturgeon ( Acipenser transmontanus ), allows us to determine the effect of water pH on acid-base compensation during hypercapnia. White sturgeon were exposed to 48 h of elevated CO 2 tensions while manipulating water pH to determine how water pH can alter patterns of acid-base compensation. Our findings demonstrate that water pH manipulation can have significant effects on the pHe compensatory response. For example, complete pHe compensation was observed in fish exposed to water equilibrated with 1 kPa CO 2 , but reducing water pH by ~1 pH unit prevented complete compensation. Alternately, when sturgeon were exposed to alkalized water equilibrated with 4 kPa CO 2 (i.e., pH of 6.3 compared to 5.7 for water with 4 kPa CO 2 ), pH compensation was more rapid. Water pH and pHe compensation rates had no effect on pH i regulation. Our findings demonstrate that water pH can aid or assist pHe compensatory rates at a range of hypercapnic challenges, and so may have contributed to the origin of PPR as a primary strategy for some fish species to protect critical tissues largely independent of environmental conditions. Summary White sturgeon were exposed to two levels of elevated CO 2 (1 and 4 kPa) in water of two different pH values, and we tracked pH compensatory responses over the following two days. Acidifying water at modest CO 2 levels within the limit for complete compensation reduced the rate at which blood pH recovered. Alkalizing water during severe hypercapnia typically beyond that limit increased both the magnitude and the rate of organismal pH compensation. Intracellular pH protection was unaffected by any treatment.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".