Freshwater and nutrient distributions in contrasting coastal domains of Hudson Bay and James Bay
Bibliographic record
Abstract
In Arctic marine environments, the renewal of surface nutrient stocks through physical and biogeochemical processes during winter is critical to support primary production later in the season when solar irradiance is sufficient. Landfast sea-ice and river discharge in the riverine coastal domain influence not only the structure of the coastal water column, but also impact the movement and distribution of nutrients within the system. Over the last several decades, both climate change and anthropogenic activities have caused shifts in both sea-ice and riverine cycles. Winter freshwater tracer and nutrient data from Canadian Arctic coastal areas, such as in Hudson Bay are extremely scarce. In this thesis I begin to fill this gap, focusing on three coastal regions: northeast James Bay (NEJB), northwest Hudson Bay (NWHB), and southeast Hudson Bay (SEHB). The objective is to evaluate the relationships between freshwater sources and nutrient distributions, during ice-covered and ice-free seasons, across the selected coastal domains. I present new nutrient (nitrate, phosphate, and silicate) and freshwater tracer (oxygen isotope ratio, salinity) data for water samples collected during ice-covered conditions, and additionally, data from open-water conditions in NEJB. Samples were collected with the help of numerous community members and guides between 2016-2019. Each region was distinct in terms of freshwater composition and influence, with NEJB strongly influenced by La Grande River, as its large under-ice plume (because of regulation) drove surface nutrient concentrations in winter (high nitrate, low phosphate). The sea-ice cycle (withdrawal of freshwater and release of brine during formation) was the dominant influence on NWHB coastal waters. Here there are large concentration ranges of nutrients within a small salinity range, possibly due to an alternate source water, or recirculation of HB outflow. SEHB coastal waters are largely influenced by riverine input from local rivers, and from the upstream James Bay outlet. Nutrient ratios showed potential nitrate limitation at salinities > 10 across all regions. Overall, this thesis provides new data that characterize a multitude of relationships between coastal freshwater sources, marine source waters, and the distribution of nutrients during winter and summer across three oceanographically different coastal regions of Hudson Bay.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| 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".