Fecal production by sea urchins in native and invaded algal beds
Bibliographic record
Abstract
To examine the role of fecal production by the sea urchin Strongylocentrotus droobachiensis in native and invaded algal assemblages in Nova Scotia, Canada, we examined the quantity (production rate by urchin feeding aggregations, or 'fronts') and quality (organic carbon and nitrogen content) of feces egested on 3 diets: (1) a native kelp Saccharina longicruris, (2) kelp encrusted with the invasive bryozoan Membranipora membranacea, and (3) an invasive green alga Codium fragile ssp. fragile. Relatively low absorption of clean and encrusted kelp resulted in high fecal output from urchins grazing native and invaded kelp beds (74 and 81 g feces m(-1) front d(-1), respectively), In contrast, high absorption of C. fragile resulted in low fecal output from urchins grazing meadows of the invasive alga (31 g feces m(-1) front d(-1)). Low C:N ratios of feces obtained from grazing C. fragile (8.5) or encrusted kelp (11.4), compared to clean kelp (30.7), suggest that feces from invaded assemblages are a higher quality food source for microbes and detritivores. To compare dispersal characteristics of feces from each diet, we measured pellet shape, size, density, and settling and critical erosion velocities. Using a wave model, we estimated the depth at which feces would be deposited under seasonally varying wave conditions. We found that pellets of C. fragile are likely deposited at the greatest depths (33 to 55 m), pellets of clean kelp at intermediate depths (28 to 47 m), and pellets of encrusted kelp at the shallowest depths (22 to 40 m). Our findings suggest a smaller amount of higher quality feces enters the detrital food web at, greater depths from Codium meadows than from native kelp beds.
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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 | 0.000 | 0.000 |
| 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) | 0.000 | 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".