Physical, chemical, and microbial diversity of cryptoendolithic habitats in the Canadian high Arctic
Bibliographic record
Abstract
Sandstone outcrops around Eureka, Ellesmere Island, Nunavut (80°N) are host to a variety of cryptoendolithic microorganisms including cyanobacteria, algae, fungi and heterotrophic bacteria. Continuous measurements over two years (2002-2004) of climate and environmental parameters show that cryptoendolithic habitats experience warmer temperatures and wetter conditions than the exposed rock surface. Subsurface temperature fluctuations are moderated by the thermal capacity of the rock substrate and vary as a function of depth, aspect, and albedo. Rain, snow or snowmelt substantially increases subsurface moisture levels, which persist for significant time periods after initial precipitation events have passed. Variation in the dominance of one microbial community over another occurs between sites, however these differences exist in habitats with similar temperature conditions. Communities grow as biofilms attached to mineral surfaces as well as within the open void spaces between grains and in many cases produce extracellular polysaccharides in response to the extreme environmental conditions. This EPS provides a substrate for accumulation of allochthonous clay particles that enter the system by winds and rain. Analysis of metal ions by sequential extraction and their relationship to microbial diversity using multivariate statistics show that cyanobacteria-dominated communities exist under higher pH conditions with elevated concentrations of calcium and magnesium, whereas communities dominated by fungi and algae are characterized by lower pH conditions and higher concentrations of iron, aluminum, and silica in overlying surfaces. These differences are explained by variations in cryptoendolithic microbial community structure, which control microenvironmental pH conditions, influence substrate dissolution and weathering rates, and perpetuate their dominance within a given cryptoendolithic habitat. Greater diversity of microorganisms at this Arctic location compared to similar habitats in the Antarctic Dry Valleys is explained by warmer temperatures during summer months that lead to longer periods for both active ( sim;3700 hr·yr-1) and ideal ( sim;2500 hr·yr-1) calculated metabolic activities as well as abundant moisture in the form of liquid water. The lack of evidence for biomineralization within this habitat contrasts with similar environments in the Antarctic Dry Valleys, a consequence of these warmer temperatures and wetter conditions that increase erosion rates and subsequent habitat destruction.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".