Influence of conductivity on life history traits of exotic and native amphipods
Bibliographic record
Abstract
Abstract: We compared the survival, growth and fecundity of the Ponto-Caspian amphipod Echinogammarus isch-nus and the North American amphipod Gammarus fasciatus across a range of conductivities in a fl uvial lake at the confl uence of the St. Lawrence and Ottawa rivers (Quebec, Canada). Previous work has found that water chemistry (conductivity) regulates the direction and intensity of intraguild predation between these two species. Because E. ischnus evolved in ion-rich waters, we hypothesized that low conductivity has a negative effect on its life history traits, whereas G. fasciatus would be more tolerant. Consistent with this hypothesis, E. ischnus is abundant along the south shore of the lake in water of high conductivity (300 µS/cm), but rare along the north shore where con-ductivity is subject to strong fl uctuations (85–230 µS/cm). In laboratory experiments using water with low (108 µS/ cm), high (300 µS/cm) and intermediate (50:50 mix) conductivities, both species showed reduced growth at low conductivity, but E. ischnus also suffered higher mortality. E. ischnus collected from both shores did not differ in size-specifi c fecundity, size at reproduction, or size of adults. On the north shore, E. ischnus was present in low abundance at one site and absent from another site where it had been recorded in previous years. We conclude that low conductivity negatively affects the growth rate and mortality of E. ischnus, which is apparently eliminated from the north shore during periods of strong infl ux of ion-poor water from the Ottawa River, but re-establishes popula-tions temporarily when higher conductivity is restored.
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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 | 0.000 | 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) | 0.001 | 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".