Indirect effects of brook trout (Salvelinus fontinalis) on the structure of epilithic algal communities in an oligotrophic boreal forest stream
Bibliographic record
Abstract
The impact of fish on epilithic algae community structure was studied in a replicated series of artificial outdoor channels fed by a boreal forest stream (Canada) to test the hypotheses that brook trout (Salvelinus fontinalis) induce a three-trophic chain top-down change in epilithic community structure, at both taxonomic and physiognomic levels. Fish were introduced into five of ten channels and the epilithic algae growing on tiles were sampled four times during summer to determine biomass, algal physiognomy and species composition in relation to presence of fish and invertebrate community structure. Diatom biomass showed distinctive development patterns, increasing at the beginning of fish introduction and decreasing towards the end of the experiment. The responses were the reverse in the absence of fish. Chrysophyceae increased in the absence of fish, particularly at the end of the experiment. From the seven algal physiognomic types considered, epilithon overstory, attached erected algae and loosely attached algae were generally more abundant in the presence of fish. Species' biomass was markedly different in both treatments and followed contrasted temporal patterns. In the presence of fish, attached erected diatoms species rapidly reached a complex spatial overstory structure, while in the absence of fish the epilithic community remained at a younger successional stage. Partial redundancy analysis showed that those changes were mediated by large grazing invertebrates, which had lower abundance over the bottom surfaces in the presence of fish. Variance partitioning analysis reinforced the hypothesis that most of the variability in epilithic community structure was explained by fish-invertebrate interactions and that the effect of fish presence alone was not significant. The results show that reduction in total epilithic algal biomass was a transient top-down effect, but the three-trophic level control on major taxa, species composition and community physiognomy remained along the summer experiment.
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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 | 0.000 | 0.001 |
| 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".