Geographical patterns in the body‐size structure of European lake fish assemblages along abiotic and biotic gradients
Bibliographic record
Abstract
Abstract Aim Our aim was to document geographical patterns of variation in the body‐size structure of European lake fish assemblages along abiotic gradients, and any differences in fish assemblage structure. We hypothesized that patterns in the body‐size structure of entire lake fish assemblages are primarily temperature driven and consistent with the dominant pattern of the temperature–size rule, which suggests a decrease in adult body size with increasing developmental temperature for many ectothermic species. Location 356 European lakes. Methods Variation in the body‐size structure of fish assemblages was explored on a continental scale along gradients of temperature, morphometry, productivity and fish assemblage structure for 356 European lakes. The mean fish assemblage body‐size and individual body‐size distributions were selected as size metrics. Separate analyses were conducted for lakes located within five ecoregion subsets (Borealic Uplands/Tundra, FennoScandian Shield, Central Plains, Western Plains and Western Highlands) and for lakes with different functional fish classifications (cold‐, cool‐ and warmwater fish assemblages). Results Geographical patterns of variation in the body‐size structure of European lake fish assemblages could be clearly discerned along a temperature gradient for both the continental dataset (356 lakes) and the smaller geographical (ecoregion) subsets. We found systematic changes in fish assemblage body‐size structure across temperature gradients in correspondence with the dominant thermal fish guild. The majority of the lakes, mainly located in the warmer European lowlands, were dominated by eurythermic cool‐ and warmwater fish assemblages, with smaller sized individuals characterized by linear individual body‐size distributions. Lakes located in colder regions and dominated by stenothermic coldwater salmonids with larger sized individuals were characterized by unimodal or bimodal size distributions. The mean body size of cold‐, cool‐ and warmwater fish assemblages changed uniformly along the temperature gradient. Main conclusions Patterns of variation in the body‐size structure of European lake fish assemblages are consistent with the temperature–size rule. Temperature modifies fish assemblage size structure uniformly within the thermal fish guilds and in different ecoregions. Furthermore, our results indicate an increasing predictive power of temperature to explain variability in body‐size structure when moving from warmer to colder geographical regions.
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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 | 0.001 |
| Science and technology studies | 0.000 | 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".