Bacterial productivity in Lake Superior, 2001: Implications for food web efficiencies in oligotrophic freshwater ecosystems
Bibliographic record
Abstract
A synoptic survey of Lake Superior from 16 to 24 August 2001 investigated heterotrophic bacterial abundance, productivity and role in phosphorus dynamics. We examined integrated surface samples (0–20 m) drawn from three nearshore (depth < 50 m) and four offshore (depth > 100 m) stations. Bacterial abundance ranged from 5.7 to 10.0 × 105 cells ml−1. Heterotrophic bacterial productivity measured using 3H-leucine and primary productivity measured using 14C-bicarbonate at nearshore stations were generally greater than at offshore stations. Bacterial productivity generally represented a greater percentage of primary productivity at stations with higher phytoplankton productivity. Phosphate as soluble reactive phosphate (SRP) was low at all stations examined but greater at nearshore stations (ave. 110 nM) than offshore (ave. 75 nM). 33P-orthophosphate uptake by size-fractionated groups indicated that greater than 61% (and up to 93%) of the instantaneous phosphate uptake was by bacteria in both nearshore and offshore habitats. Bacterial phosphorus use efficiency (production per mole of P taken up) was greatest at stations where primary productivity exceeded 1.5 μ g C l−1 h−1. Where bacterial phosphorus use efficiency is relatively low, the phosphorus-to-carbon ratio was relatively high, suggesting that bacterioplankton may be especially important in phosphorus-dynamics and that bacterivory may be an especially important process mobilizing phosphorus to higher trophic levels in Lake Superior and ultraoligotrophic aquatic communities in general. The implications for emerging issues of investigation in Lake Superior are discussed in the context of contemporary marine and freshwater research.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".