Daily movement of the sea urchin Strongylocentrotus droebachiensis in different subtidal habitats in eastern Canada
Bibliographic record
Abstract
We measured the movement and orientation of sea urchins at 2 sites in each of 4 habitats on urchin barrens in the northern Gulf of St. Lawrence, eastern Canada.We tagged the urchins measuring 25 to 70 mm in test diameter using a non-invasive technique involving a knot of fine monofilament thread tied around one spine.Smaller urchins (< 25 mm) were tagged by tightening a loop around the test.Daily displacement increased markedly going from large juveniles (measuring 10-15 mm in diameter) to small adults (15-20 mm) and from small adults to large adults (> 25-70 mm); however, no effect of size was detectable among large adults measuring from 25 to 70 mm.The increased movement with size was associated with a change in foraging, as gut analysis revealed a marked increase in the proportion of brown algae with increasing size.For large adults, the maximum net distance displaced per day varied among sites from 1.0 to 4.9 m d -1 , and mean displacement varied from 0.40 (SE = 0.07) to 1.72 (SE = 0.28) m d -1 .Distance moved also varied with habitat, and was greater in habitats that were further from kelp beds.Orientation was random and individuals showed frequent reverses in direction from day to day.Hunger state did not affect displacement, as there was no difference in distance moved between starved and fed urchins which were released in the barrens.However, urchins transplanted from kelp beds to the barrens were less active than urchins removed from and returned to the barrens.The shifts in movement with size are probably important in determining the size structure of urchins at different depths.The great distance covered by larger urchins as they move over open surfaces in search of favourable resources probably leads to their increased numbers in shallow habitats where food is abundant.
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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 | 0.001 | 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".