Dissolved organic carbon from “white” waters in Amazon basin (Brazil) and the osmoregulatory responses of tambaqui ( <scp> <i>Colossoma macropomum</i> </scp> ) in neutral and acidic environments
Bibliographic record
Abstract
Abstract Optical characterization of dissolved organic carbon (DOC) freshly collected from the circumneutral “white water” of the Rio Solimoes revealed that it had lower aromaticity, lower molecular weight, and a greater autochthonous content than DOC from the acidic “black water” of the Rio Negro. The tambaqui ( Colossoma macropomum ), a characid member of the Serrasalmidae, is a model neotropical fish that migrates annually between the two rivers. We analysed ionoregulatory responses of the tambaqui over 24 h in ion‐poor water at pH 7.0 and pH 4.0 in the absence and presence of 10 mg L −1 Rio Solimoes DOC (“SOL DOC”). Measured parameters included transepithelial potential (TEP) across the gills, net flux rates, and plasma concentrations of Na + , Cl − , ammonia, and urea, and branchial Na + , K + −ATPase, H + , ATPase, and carbonic anhydrase activities. Results were compared to our earlier study using similar protocols to examine the ionoregulatory effects of 10 mg L −1 DOC (“SGC DOC”) collected from black water at São Gabriel da Cachoeira (SGC) in the upper Rio Negro. At pH 7.0, SOL DOC had no effect on the negative TEP across the gills. Exposure to pH 4.0 caused a marked depolarization of the TEP to positive values that was not ameliorated by the presence of SOL DOC. This contrasts with SGC DOC that drove TEP more negative at pH 7.0 and fully protected against the depolarization at pH 4.0. However, SOL DOC promoted positive balance of Na + and Cl − at pH 7.0 and helped ameliorate the negative balance of these ions seen at pH 4.0. This again contrasts with SGC DOC that exacerbated ion losses at pH 4.0. The protective effects of SOL DOC on ion balance maybe related to increased v‐type H + ATPase activity in the gills, and unrelated to TEP. The very different responses to the two DOCs are discussed with respect to their optical properties, the time that they were in storage prior to testing (SOL <1 month, SGC 2 years), and the life history of the tambaqui in the two rivers.
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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".