Temporal trends and causes of deoxygenation: a comparison of the Northwest Atlantic Shelf and Atlantic Basin
Bibliographic record
Abstract
Oxygen concentrations are of fundamental importance for organisms as well as geochemical cycling in oceans. Since the middle of the 20th century, oxygen concentrations have been declining in the open ocean and the coastal ocean. Located near the intersection of subtropical and subpolar circulation, the northwest Atlantic (NWA) Shelf is sensitive to climate variability. Recent work has been done on regional NWA trends in sea-surface temperature, salinity, and chlorophyll, but the trends and drivers of oxygen in the region have not yet been established. Here, we use World Ocean Database oxygen observations to determine the temporal trend of subsurface oxygen concentrations between 50-100m on the NWA Shelf from 1988 to 2019. We also use a regional NWA ROMS and MOM6 configuration to simulate the historical decadal trends and spatial patterns in dissolved oxygen concentrations over the shelf. Our results indicate a significant decrease of oxygen by 1.542±0.308 µmol/kg/year, which surpasses the established Atlantic basin-wide trend. The greatest subregional oxygen loss occurs on the Scotian Shelf and in the Gulf of St. Lawrence. A detailed analysis revealed that the oxygen trends on the NWA shelf are driven by changes in Apparent Oxygen Utilization (AOU), consistent with the decreased influence of Labrador Current in the region and associated water mass properties. Our model identifies the location of minimum oxygen concentrations occurring both at the bottom but also at midwater column depths in the Mid-Atlantic Bight and Gulf of Maine. Under SSP5-8.5, our dynamically downscaled projection (2014-2098) projects that the bottom oxygen in the NWA Shelf will accelerate relative to the historical period (1980-2014). Diagnosis of the mechanisms behind the future acceleration as well as the mid-water column minimum oxygen pattern using various tools will be presented.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.001 |
| 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".