Versatile photophysiology of compositionally similar cyanobacterial mat communities inhabiting submerged sinkholes of Lake Huron
Bibliographic record
Abstract
Recently discovered submerged sinkholes in Lake Huron are high-sulfur, lowoxygen extreme environments for microbial life.In order to understand the relationship between the physical environment, photophysiology and community composition, we measured the physical conditions, photophysiological indices, and genetic diversity at 3 microbial mat sites bathed in high conductivity groundwater under a natural light gradient during 2012 and 2013.A strong seasonal trend prevailed at all sites, characterized by decreased photosynthetic yield (F v '/F m '; 0.25 to 0.40) during the summer (April to August) and increased yield (0.70 to 0.75) during the winter (November to March).Chlorophyll a content varied seasonally in a similar manner to photosynthetic yield.All sites were dominated by > 80% abundance of one cyanobacterial group, most closely related to Phormidium sp.Phycobilins (phycocyanin and phycoerythrin) were consistently higher in concentration than chlorophyll.Photosynthetic yield was statistically indistinguishable between sites, suggesting that these mat communities are able to acclimate across a wide range of photosynthetically active radiation (PAR).Interestingly, these cyanobacteria carried out oxygenic photosynthesis in the presence of in vitro H 2 S, further suggestive of their versatile photophysiologies under variable redox conditions.Collectively, our study provides insight into the adaptive capabilities of cyanobacteria by revealing how they photophysiologically respond to changes in light climate and redox conditions, and are thereby able to inhabit a wide range of physico-chemical environments.Such versatile physiologies may have enabled their ancestors to thrive across a range of habitats on early Earth.
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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) | 0.000 | 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".