Extant mat microbes synchronize vertical migration to a diel tempo
Bibliographic record
Abstract
Animal migrations mark the largest daily movement of biomass on Earth today, but who performed the first diel migration and what are the implications? Modern-day benthic microbial mats resembling those of early Earth inhabit Lake Huron’s low-oxygen, high-sulfur, submerged sinkholes. Over several days during multiple years, we gathered time-lapse images of motile, phototactic, purple-pigmented cyanobacteria capable of oxygenic and anoxygenic photosynthesis, and chemotactic, pigment-free, chemosynthetic sulfur-oxidizing bacteria indulging in diel vertical migration of just 1–2 mm across the mat-sediment interface. As the world turns, alternating waves of vertically migrating photosynthetic and chemosynthetic filaments responded rapidly and non-linearly to daily fluctuating sunlight and chemical gradients. The photosynthesizing cyanobacteria and sulfur oxidizing bacteria exhibited their fastest motility following dawn and dusk, which turned the mat surface visibly purple during day and white at night, respectively. Our high-frequency, time-lapse images visually capture a modern day synchronized diel migration similar to what might have been the first and largest daily mass movement of life during the long Precambrian. During that time, benthic microbial mat motility would have played a critical role in directly optimizing photosynthesis and chemosynthesis, as well as indirectly burying carbon and oxygenating the biosphere. Further studies of these mat ecosystems will add to the expanding knowledge of Earth’s extant biodiversity and physiologies.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".