Bibliographic record
Abstract
Abstract. Deep-sea sponge grounds are distributed globally and are considered hotspots of biological diversity and biogeochemical cycling. To date, little is known about the environmental constraints that control where deep-sea sponge grounds occur and what conditions allow high sponge biomass to develop in the deep sea. Here, we characterize oceanographic conditions at two contrasting high- and low-sponge-biomass sites off the northern Labrador Shelf in Canadian waters. Unique data for the region were collected by year-long benthic lander deployments equipped with current meters, turbidity and chlorophyll-a sensors, and sediment traps. Additionally, the regional oceanography was described by analysing vertical conductivity/salinity-temperature-depth (CTD) and Argo float profiles for the Northern Labrador Shelf from 2005 to 2022, including those from the CTD casts taken at the benthic lander stations. Benthic fauna stable isotopes were analysed to identify potential food sources. Our results revealed strong (0.26 ± 0.14 m s-1; mean ± SD) semidiurnal tidal currents at the high-sponge-biomass site, but twofold weaker currents (0.14 ± 0.08 m s-1; mean ± SD) at the low-sponge-biomass site. These tidal currents cause periodic temperature fluctuations, sediment resuspension, intense vertical flows across the slope, which during spring, contribute to transport of organic material to the seafloor during a diurnal tidal cycle. Periodic fluctuations in bottom water temperature confirm the amplified transport across the shelf break at the high-sponge-biomass site. The high-sponge-biomass area is situated where the Hudson Strait Ouflow, the Irminger Current, and the West Greenland Current converge, which could lead to downwelling. Bottom silicate concentrations were increased at the high-biomass sponge ground due to advection of silicate-rich bottom water from Baffin Bay. Finally, the arrival of chlorophyll-a rich material in spring at both the low- and high-sponge-biomass sites demonstrated tight benthic-pelagic coupling prior to the onset of stratification. Mass fluxes of trapped material were higher and consisted of less degraded material at the high-sponge-biomass site. Stable isotope signatures indicated that soft corals (Primnoa resedaeformis) fed on suspended particulate organic matter, while massive sponges (Geodia spp.) likely utilized additional food sources. Our results imply that benthic fauna at the high-sponge-biomass site benefit from strong tidal currents, which increases food supply, and favourable regional ocean currents that increase nutrient concentration in bottom waters.
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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 | 0.002 | 0.018 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.020 | 0.018 |
| Insufficient payload (model declined to judge) | 0.161 | 0.133 |
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".