Rock bottom: Colonization patterns of deep-sea Arctic and subarctic dropstones (200–1300 m)
Bibliographic record
Abstract
Hard substrata of allochthonous origin, such as ice-rafted dropstones, can provide essential habitat for benthic communities in the polar and subpolar deep sea, acting as “islands” in otherwise finer-grained sedimentary environments . The present study explored the diversity and distribution patterns of morphospecies (msp/mspp) present on dropstones collected at depths of ∼200–500 m in the Labrador Sea (LAB) and ∼700–1300 m in Baffin Bay (BAF), respectively spanning subarctic and Arctic regions of eastern Canada. Specifically, the zonation, intra- and interspecific interactions , and succession of all colonizers were examined. Based on in - situ images, dropstones exhibited ∼94% greater epibenthic megafaunal richness than similar surfaces of the substratum immediately surrounding them. Analysis of three dropstones collected from each of six sites documented a total of 101 sessile and motile taxa spanning 10 phyla. Across sites, bryozoans dominated at all depths and locations (27 mspp, plus 3 dead) followed by poriferans (27 mspp), 19 cnidarians , eight arthropods, eight annelids, five chordates (tunicates), three echinoderms, three molluscs, and one foraminifer. There were 19 mspp that spanned both LAB and BAF, with greater overall richness in the subarctic region (62 vs 26 mspp). A total of 64 sessile mspp occurred above the stone-sediment interface (e.g., cnidarians and poriferans), whereas 22 mspp (mostly bryozoans) occurred at the stone-sediment interface; one morphospecies of polychaete occurred below. The most abundant morphospecies was an arborescent bryozoan, while two encrusting bryozoans covered the most surface area . Eight morphospecies occurred as just one individual or colony per stone, and 35 mspp appeared to maintain an exclusion zone between conspecifics (e.g., tube-dwelling annelids, hydrozoans , and anthozoans). Conversely, in 51 mspp conspecifics occurred abutting one another (e.g., bryozoans and poriferans). Allospecific exclusion zones appeared to occur in 27 mspp (e.g., bryozoans and annelids), whereas 59 allospecifics (e.g., poriferans, cnidarians, and chordates) occurred within touching distance. Secondary colonization (including cases of epibiosis) was observed in 83 mspp, documenting 204 unique pairings of hosts and colonizers. The number and diversity of morphospecies colonizing dropstones in the deep sea of the eastern Canadian Arctic and subarctic support the role of dropstones as oases that facilitate connectivity in an otherwise poorly diversified epibenthic environment.
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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 | 0.000 |
| Scholarly communication | 0.000 | 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".