The effect of acetolysis on desmids
Bibliographic record
Abstract
Acetolysis, an oxidising technique common in palynological preparation, is beneficial for pollen analysts who employ it to remove ‘unwanted’ organic matter from peat and lake samples. Since this technique was introduced by G. Erdtman in 1934, however, several researches have noted concerns, such as the destruction of thin-walled pollen grains in addition to non-sporopollenin pollen components, and selective destruction of protoperidinioid dinoflagellate cysts. Desmids are conjugate green algae with a wide range of environmental preferences whose half-cells are known from sediments dating back to at least the Neogene (possibly as far back as the Devonian), and they have proven useful in modern and palaeolimnological studies (e.g. as indicators of nutrient loading, anthropogenic impact and drought). Desmids are rarely mentioned in palynological studies, however, except to illustrate fluvial transport to nearshore marine settings. A diverse desmid flora was found in samples processed without acetolysis from Smith's Bay in Lake Simcoe, and desmid and thecamoebian (testate amoeba) assemblage changes record eutrophication up-core. Very low concentrations of both desmids and Pediastrum, another group of algal non-pollen palynomorphs (NPP), record siltation and inhibition of photosynthesis attributed to two phases of land-clearing and agriculture (Wendat/Huron and Euro-Canadian). After acetolysis, the desmid abundance in the same residues drops significantly (between 36 and 100%, mean = 87%) and the assemblage is skewed towards the most robust Cosmarium spp. However, other low-relief NPP, like Pediastrum, may be easier to observe after acetolysis as they are not obscured by amorphous organic matter. Because of the observed detrimental impact acetolysis has on the desmid assemblage, recommendations include: (i) not acetolysing, as pollen and Pediastrum can be observed either way, or (ii) using a two-pronged approach where susceptible microfossils are observed pre-acetolysis and resistant ones observed post-acetolysis.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".