Winterkill cascade: indirect effects of a natural disturbance on littoral macroinvertebrates in boreal lakes
Bibliographic record
Abstract
Natural disturbances can provide insights into mechanisms organizing communities by perturbing systems at larger scales and more realistic intensities than can often be achieved otherwise. We took advantage of 2 winterkills of fish, a common disturbance of small lakes on the Boreal Plains of northern Alberta (Canada), to assess the effects of sudden, large reductions in fish densities on littoral macroinvertebrate assemblages. Winterkill nearly eliminated the native fish assemblages (dominated by northern pike, Esox lucius, and yellow perch, Perca flavescens) in the 2 lakes, whereas 2 nearby lakes with similar fish assemblages were unaffected and served as references. Environmental characteristics of both winterkill and reference lakes changed little from year to year. Uni- and multivariate analyses of macroinvertebrates revealed some inherent among-lake differences; however, strong and parallel changes in the invertebrate assemblages occurred only in the 2 winterkill lakes, congruent with the winterkills of fish. Decreases in fish biomass were generally accompanied by increases in macroinvertebrate density, particularly among taxa (e.g., amphipods, leeches, chironomids) commonly eaten by the native fish. As a result, analyses of matrix concordance and variance partitioning showed variation in macroinvertebrate assemblages was related to both temporal changes in fish density and environmental differences among lakes but that the fish and environmental matrices were not strongly concordant. Our serendipitous study of community-level disturbance revealed that winterkill-induced reductions of fish densities can have strong, cascading effects on littoral macroinvertebrates in these boreal lakes.
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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".