Organic matter sources and size structuring in stream invertebrate food webs across a tropical to temperate gradient
Bibliographic record
Abstract
Summary Given large differences in species diversity across latitudinal gradients, it has been suggested that certain structural and functional attributes of fresh waters may differ over a latitudinal range, an important consideration for poorly known tropical systems undergoing major changes caused by human activities. Two key features of aquatic ecosystems, the contribution of in situ production (periphyton) to community biomass and size structuring (individual body size versus trophic position), were measured in stream invertebrate food webs across a gradient of 15 degrees of latitude in Australia from the wet tropics to a temperate island. Consistent with earlier work, crustaceans (Atyidae and Palaemonidae) were responsible for a large fraction of the community biomass at tropical and subtropical sites. Periphyton supported a large proportion of the biomass at intermediate latitudes (79% in the subtropics and 95% at temperate mainland sites), with lower contributions both in more northerly (51% in the tropics) and more southerly (31% on a temperate island) sites. These lower contributions were driven by the high biomass of large crustaceans in the tropics and by shredding and filtering insects on the temperate island and may have also been the result of local nutrient‐limitation. Although these taxonomic differences between regions did not translate into a latitudinal gradient in size structure, the larger individual body size of crustaceans compared with insects at a given trophic position suggests that the distribution of biomass in tropical and temperate food webs will differ, with implications for predators near the top of the web. These results suggest that differences in species composition do not necessarily entail differences in stream food‐web structure and function and that local environmental factors are likely to be as important as broad‐scale biogeography and climate in driving food‐web patterns.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".