Stratification and summer protist communities in the Arctic influenced coastal systems of Nunavik (Québec, Canada)
Bibliographic record
Abstract
Phytoplankton and other protists in the 3 µm to 50 µm size fraction are grazed on by zooplankton and form the base of Arctic marine food webs essential for local indigenous communities. Anthropogenic climate change is increasing stratification over much of the Arctic Ocean and surrounding seas, but the influence of stratification on protist communities in more coastal regions along Eastern Hudson Bay, Hudson Strait and Ungava Bay is little known. We used 18S rRNA and rDNA amplicon sequencing during two consecutive summers (2017 and 2018) and detailed water column properties to compare the 3 µm to 50 µm protist communities under contrasting stratification regimes in the Eastern Hudson Bay Complex. We found that the surface mixed layer in Eastern Hudson Bay, which is under the influence of river runoff, was strongly stratified and dominated by mixotrophic and bacterivorous taxa, mostly the dinoflagellates Heterocapsa rotundata and Gymnodiniales spp., and a more diatom-dominated community at the Subsurface Chlorophyll Maximum (SCM), which persisted in deeper colder and more saline water. The massive sequencing effort retrieved seven putative toxic algae from the upper warmer waters of eastern Hudson Bay. These included Pseudo-nitzschia spp. and potentially harmful dinoflagellates, most notably Alexandrium sp. The persistent weaker stratification conditions in Hudson Strait and Ungava Bay in summer favored a different diatom community, dominated by Chaetoceros spp. and Thalassiosira spp., and small photosynthetic flagellates including Phaeocystis pouchetii and Micromonas polaris. As freshwater input increases and stratification intensifies in the Arctic, our findings suggest the summer dinoflagellate-based community seen in coastal Hudson Bay may also be favored in other regions receiving increased river runoff. These conditions could also favor harmful algal events. The Hudson Strait and Ungava Bay protist communities were found nearer the surface and consisted of diverse species able to profit from ongoing nutrient input due to tidal mixing. These results suggest greater resilience in this and other tidally influenced coastal Arctic Bays lacking larger rivers inputs.
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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 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".