Degradation of sea urchin feces in a rocky subtidal ecosystem: implications for nutrient cycling and energy flow
Why this work is in the frame
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Bibliographic record
Abstract
During destructive grazing events in the Northwest Atlantic, sea urchins Strongylocentrotus droebachiensis consume large amounts of kelp biomass, transforming this material into feces. To determine the role of urchin fecal material in nutrient cycling and energy flow in the shallow rocky subtidal zone, we monitored the physical, chemical, and microbial degradation of urchin feces at 6, 9, 12, and 16 m depth over 19 d at a wave-exposed site on the Atlantic coast of Nova Scotia by quantifying changes in fecal biochemical composition, pellet size, and settling velocity. We observed an exponential loss of fecal material and rapid degradation of total and labile organic matter fractions; this suggests that urchin fecal production plays an important role in local nutrient cycling and energy flow via the microbial food web. As the feces were further degraded there was a relative increase in organic carbon, nitrogen, lipid, and available energy content, and a decrease in the C:N ratio, suggesting that degraded urchin feces are an important food source for suspension-and deposit-feeding invertebrates. The settling velocity of the feces also decreased over time, likely due to a decrease in fecal pellet density. Older, less dense feces with a relatively high energy content are more likely to be suspended and transported horizontally, providing a mechanism for the export of kelp primary production to deeper, less productive waters.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 it