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 13 C values for the 2 mysid species were similar and supported by the same carbon source, mostly of autochthonous origin. However, their 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 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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 teacher head, 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".