Factors affecting the abundance and size of Pisaster ocharceus in the rocky intertidal zone of southern British Columbia
Bibliographic record
Abstract
This study investigates the abiotic and biotic factors that affect the abundance and distribution of the sea star Pisaster ocharceus in the intertidal zone of Southern British Columbia (B.C.). P. ochraceus is very important to the intertidal community as it is seen as a keystone species because when its numbers are reduced, mussels are seen to out-compete all other organisms, reducing the species richness of the community. Climate change is expected to impact strongly on intertidal habitats and there is a strong possibility that intertidal habitats may serve as a bellwether for change in other ecosystems. During June and July 2008, 16 sites were visited along the south coast of B.C., 12 abiotic and biotic variables were recorded and all P. ochraceus individuals were counted and measured within a 50 m transect at each site. Across all sites, 25% contained no P. ochraceus. The abundance of sea stars ranged from 0 to 255 individuals. The mean size (diameter) of individuals ranged from 4.7 to 23.5 cm. Human disturbance (P = 0.001) was found to be significant, negatively linked to the size of P. ochraceus. Although no significant results were found with regard to the abundance of P. ochraceus, human disturbance (P = 0.080) and exposed sites (P = 0.079) just failed to reach significance. These finding indicate that anthropogenic factors such as human disturbance are having a negative impact of P. ochraceus. This study serves as a pilot for further research in this area, a more in depth large-scale study of P. ochraceus is needed to obtain greater insight into its abundance and size distribution and the factors which influence them.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".