Conspecific interactions as drivers of activity and mortality in a prominent sandy beach amphipod
Bibliographic record
Abstract
In harsh habitats, community structure is believed to be controlled primarily by physical factors while biological interactions are considered to be of little relevance. However, evidence of avoidance behaviors between the life stages of some species suggests otherwise. A long-standing hypothesis from sandy beaches suggests that avoidance between adults and juveniles dictates some aspects of their ecology, but this has not been explicitly tested. Here, we used a field survey to document the diel activity of adults and juveniles of the talitrid amphipod Americorchestia longicornis. We then used laboratory experiments to assess the influence of adults on the activity of juveniles and to measure juvenile mortality rates in the presence and absence of adults, with and without food. In the field, we found clear differences in the diel activity of adults and juveniles. Adults were active throughout the night but not in daylight, whereas juvenile activity peaked at dusk and dawn. Similar patterns of activity were recorded in laboratory tanks that included both stages. However, when adults were excluded, juveniles shifted towards night activity, suggesting that the pattern of activity observed in the field is a mechanism to avoid larger conspecifics. In separate trials, predation by adults was a significant driver of juvenile mortality, regardless of initial juvenile density and food availability. Altogether, these results suggest that segregation between amphipod life stages is driven by the avoidance of direct interactions, specifically, cannibalism. This likely influences the role played by these amphipods, both as prey and as processors of stranded seaweeds.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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".