Abundance of Bacteria, the Cytophaga-Flavobacterium cluster and Archaea in cold oligotrophic waters and nepheloid layers of the Northwest Passage, Canadian Archipelago
Bibliographic record
Abstract
We used fluorescent in situ hybridization and epifluorescence microscopy to assess the distribution and diversity of pelagic microorganisms, specifically Bacteria, the Cytophaga-Flavobacterium (CF) cluster and Archaea, in the cold (-1.5 to 3.5C) and oligotrophic waters of the Northwest Passage, Canadian Arctic, during September 2000. Total cell abundance ranged from 1.23 to 6.56 10 5 cells ml -1 , approximately half of which were hybridizable; Bacteria dominated the region (67 to 99.8% of hybridizable cells). CF were well-represented in the surface-water bacterioplankton, accounting for 9 to 41% of the total cell count (21 to 76% of hybridizable cells), but not in deeper populations: in nepheloid (particle-rich) layers, they accounted for only 1.6 to 5.4% of total cells (3.2 to 9.5% of hybridizable cells) despite the available substrata for attachment, a behavior common to this group. Over the entire data set, often highly significant (p < 0.001) correlations with environmental variables, including oxygen, particulate organic nitrogen (PON) and chlorophyll a (chl a) (positive) and depth, salinity and macronutrients (negative) suggested the importance of CF as aerobic heterotrophic consumers in this environment. In marked contrast, Archaea were present at very low levels (0.1 to 2.6% of total cells; 0.2 to 4.6% of hybridizable cells) in the surface waters, becoming more abundant in nepheloid layers, where they accounted for 2.3 to 13% of total cells (3.9 to 33% of hybridizable cells). Archaea correlated highly significantly (p < 0.001) with concentrations of particles and, in nepheloid layers, with PON. Over the entire data set, Archaea and Bacteria correlated significantly but oppositely to the same environmental variables of depth, salinity, oxygen and macro-nutrients, suggesting separate niches in this setting. In general, our results substantiate and extend the growing evidence for the numerical importance of CF in cold marine surface waters and further document the distribution and oceanographic context of the planktonic Archaea to include nepheloid layers.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".