Effects of water clarity and other environmental factors on trophic niches of two sympatric piscivores
Bibliographic record
Abstract
Summary Water clarity can have a profound influence on aquatic ecosystem structure and processes via its effects on physical habitat (e.g., thermal regime, macrophyte density) and behavioural responses of biota (e.g., predator avoidance, reaction distances, foraging efficiency). Changes in foraging efficiencies under varying water clarity conditions are well documented for many freshwater piscivores in laboratory studies, but the influence of visual foraging conditions on interspecific trophic dynamics is poorly understood in wild populations, especially within water clarity ranges that are realistic for north‐temperate boreal lakes. Here, we used stable isotopes of nitrogen ( 15 N / 14 N ) and carbon ( 13 C / 12 C ) in fish muscle tissue to investigate how resource partitioning between two sympatric visual piscivores is related to water clarity and other habitat variables in 28 small (100–200 ha) B oreal S hield lakes. One of the species is adapted for foraging in low subsurface illumination (walleye, S ander vitreus ) and the other in high subsurface illumination (smallmouth bass, M icropterus dolomieu ). Trophic niche dimensions of the dark‐adapted predator did not respond significantly to differences in water clarity. In contrast, total isotopic niche space of the light‐adapted predator decreased significantly with increasing water clarity through greater use of pelagic resources and a narrower range of trophic levels, although these relationships were weak. Niche overlap ranged from 0 to 65%, but was not significantly related to water clarity. Rather, indices of prey availability appeared to be much stronger predictors of trophic interactions. Both species occupied more similar food‐web positions when yellow perch ( P erca flavescens ) abundance was higher, and had more similar niche size and trophic evenness with decreasing prey fish species richness. Results indicate that the trophic ecology of predators adapted to foraging in low light conditions is less influenced by water clarity than that of predators adapted to foraging in high light conditions. However, prey availability, rather than the environmental conditions in which foraging occurs, may be a more important driver of resource partitioning among generalists even when light conditions favour one species’ foraging strategy over another.
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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 | 0.000 | 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 | 0.000 | 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) | 0.000 | 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 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".