Metabolic rates and spontaneous swimming activity of two krill species (Euphausiacea) under different temperature regimes in the St. Lawrence Estuary, Canada
Bibliographic record
Abstract
Two dominant krill species Meganyctiphanes norvegica (Sars, 1857) and Thysanoessa raschii (Sars, 1864) coexist in the subarctic waters of lower St. Lawrence Estuary, Canada. Both species perform diel vertical migrations representing often large displacements of ~100–150 m through several temperature regimes. We studied the impact of temperature, a fundamental factor controlling the metabolism of ectothermic species, on the metabolic rate and swimming activity of the two species. Annular respirometers were used to quantify simultaneously oxygen consumption (ṀO2 g–1 wet mass) and the spontaneous swimming activity of individual krill over a period of 24 h at six temperatures, by intermittent-flow respirometry. Both species significantly increased their low routine and maximal metabolic rates from 0 °C to 15 °C, suggesting high thermal plasticity. The spontaneous swimming activity of M. norvegica was reduced to almost zero at 0 °C, whereas T. raschii swam 1.0 cm s–1 at this temperature. Based on swimming performance, M. norvegica might avoid the cold intermediate layer (CIL, < 1 °C) in the estuary, which coincides with actual daytime distribution below the CIL in the warmer deep-water layer. Despite the rare occurrence of 15 °C in the estuary, both species still showed high metabolic and swimming performance at that temperature. High and differential thermal plasticity of both krill species might have important ecological consequences for their distribution patterns in their natural environment, as energy requirements differ in the two species.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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 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".