Bioavailable iron in oligotrophic Lake Superior assessed using biological reporters
Bibliographic record
Abstract
Iron bioavailability in Lake Superior was assessed during field surveys conducted in 2001–2002. Dissolved iron (Fed) ranged between 1 and 4 nM at offshore stations and >10 nM at most nearshore sites. Iron availability was assessed using a luminescent Synechococcus bioreporter comprising a luciferase reporter controlled by an iron-responsive promoter isiAB. Bioreporter luminescence was negatively correlated to Fed measured in the samples. Distance from shore was a better predictor of iron bioavailability than was season. Water collected from most offshore stations sampled during spring and summer elicited higher bioreporter luminescence than did nearshore sites. Iron availability did not vary with depth during summer, despite the presence of elevated levels of Fed in the hypolimnion at most stations. Ultrafiltration (0.02 μm) of Fed at two offshore sites demonstrated Fed to be present mainly in a colloidal phase, yet the bioreporter responded solely to iron contained in the soluble phase. During spring, a parallel immunochemical assay of diatoms resulted in the detection of ferredoxin (Fd) but not flavodoxin (Flvd) at five stations indicating the presence of an iron sufficient assemblage of diatoms at these sites. Whereas neither bioreporter nor immunochemical approaches conducted during spring supported physiological iron deficiency among Lake Superior phytoplankton, the results did point to differences in the availability of iron to prokaryotes and eukaryotes.
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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".