Trophic dynamics of two sympatric mysid species in an estuarine transition zone
Bibliographic record
Abstract
The feeding ecology of 2 sympatric mysid species within the food web of the St. Lawrence Middle Estuary was studied to determine their trophic position and potential mechanisms of coexistence.These abundant predators were clearly distinguished by differences in foraging behaviour.In feeding experiments involving multi-prey assemblages, predation and ingestion rates of Mysis stenolepis were greater than for Neomysis americana, except for small prey.M. stenolepis showed highest predation rates on and preference for Eurytemora affinis nauplii and copepodites, and did not feed on the most abundant prey, the veliger stage of the zebra mussel Dreissena polymorpha.In contrast, N. americana showed highest predation rates on and preference for small prey species such as rotifers, nauplii and veligers.When densities of preferred prey declined in the second half of the experiment, both mysid species showed a shift in predation towards the less preferred prey.M. stenolepis switched to filter feeding, with higher predation rates on veligers, whereas N. americana increased predation on small E. affinis copepodites.Stable isotope analysis and feeding experiments suggested 3 trophic levels in the food web, with a high degree of omnivory.The δ 13 C values for the 2 mysid species were similar and supported by the same carbon source, mostly of autochthonous origin.However, their δ 15 N differed significantly by 2.2 ‰, indicating that the composition of their diet differed in terms of ingested and assimilated food items.These results suggest that co-existence of the sympatric mysid populations is achieved by reduced competition due to foodniche partitioning.Flexibility in their foraging behaviour allowed mysids to exploit multiple prey groups that undergo temporal and spatial fluctuations in the highly dynamic estuarine transition zone of the St. Lawrence Middle Estuary.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 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".