The Last Interglacial in the Labrador Sea: a sedimentary ancient DNA investigation 
Bibliographic record
Abstract
The Last Interglacial (LIG, ~128–116ka) was characterized by a warmer climate, increased sea level, and a reduced Greenland ice sheet compared to today. Climate projections suggest our future climate may resemble LIG conditions if anthropogenic climate change progresses unabated. Previous studies have identified key shifts in the Labrador Sea oceanography and climate before, during, and after the LIG, making this time interval an exciting target for exploring high-latitude marine ecological dynamics. In recent years, the application of sedimentary ancient DNA (sedaDNA) has provided new glimpses into past ocean and climate conditions. Here, we have explored sedaDNA alongside other, traditional, paleoceanography proxies, to better understand the changing Labrador Sea biome across climate transitions and in a globally warmer world. We have generated a sedaDNA record from a giant piston core at the Eirik Drift (Labrador Sea). Our sedaDNA record, dating back to ~135 ka, was sampled at 4 cm depth intervals and covers the glacial-interglacial transition, as well as the LIG. SedaDNA was purified using a commercial spin column kit and analysed using a metabarcoding approach targeting the V7 hypervariable region of the eukaryote small subunit RNA. Illumina MiSeq analysis of metabarcoding libraries revealed PCR-amplifiable eukaryotic DNA throughout the investigated downcore section. Shifts in relative taxon abundance and alpha- and beta-diversity metrics paralleled shifts in foraminifer isotope records (δ18Ο), palynological assemblages, and biomarkers suggesting that the molecular genetic signal preserved in downcore sediments shows promise for identifying ecological shifts across the LIG. We are currently investigating the potential utility of specific taxa identified in the sedaDNA record to act as indicators of the glacial-interglacial transition. This study strengthens the growing potential of marine sedaDNA as a supplemental proxy for climate reconstructions in the Late Quaternary.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 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".