Effects of formalin and ethanol preservation on otolith <i>δ</i><sup>18</sup>O stable isotope signatures
Bibliographic record
Abstract
The use of preserved otoliths for stable isotope analysis assumes handling and preservation procedures do not alter the isotopic composition of the otolith. Otoliths from wild and hatchery-reared salmonids (brook charr, Salvelinus fontinalis, and Atlantic salmon, Salmo salar) were used to test for possible delta(18)O preservation effects in ethanol and formalin preservation experiments at varying temperatures. Analysis of variance (ANOVA) demonstrated a significant interaction effect between species and preservative during preservation. Possible causes for the observed effect are discussed in relation to species-specific differences in otolith chemistry related to growth and environment including: (1) chemical mechanisms of dissolution-recrystallisation involving the precipitation of secondary minerals within and at the otolith surface; (2) adsorption of ions at available binding sites on the otolith surface; and (3) isotopic exchange during otolith surface dissolution and/or reprecipitation processes. Differential occurrence of vaterite and aragonite in otoliths is believed to account for some of the observed effects as a result of otolith density differences. Isotopic exchange is also argued to cause much of the observed variation in species-specific preservation effects. Biologically, study findings imply that preserved otoliths should not be used for baseline paleoclimatic or individual fish thermal reconstructions, or the development of delta(18)O-fractionation equations, without the prior use of pilot studies to determine preservation effects.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".