Resource subsidies from adfluvial fishes increase stream productivity
Bibliographic record
Abstract
Summary Anadromous fishes are well known to shape the structure and function of recipient ecosystems by introducing nutrients and rich organic matter from the ocean. In contrast, the importance of potamodromous migrations, confined to freshwater, and the subsidies they provide to stream ecosystems has received much less attention. Our objective was to determine the importance of excretion, eggs, milt, and carcasses as nutrient and energy sources from a large population (82 449 suckers) of migrating longnose ( Catostomus catostomus ) and common white ( Catostomus commersonii ) suckers into a small (wetted width c . 10 m) oligotrophic river system. We hypothesise that the adfluvial suckers provide a large material subsidy that increased the productivity of the Cypress River and that this resource subsidy rivals or exceeds those delivered by other native and non‐native fishes (e.g. Pacific salmonids). In total there was an estimated 5635 kg of eggs, 2025 kg of milt, and 1 kg of carcasses from suckers that spawn in the Cypress River. Relative to other mainly non‐native fishes, suckers provided 92% of the annual egg biomass and 95% of the milt. Suckers, however, only provided <1% (1 kg) of the annual carcass biomass, whereas, pink salmon provided 50% (600 kg). Overall, suckers provided 84% and 78% of the annual subsidies of N and P, or 212 and 14 kg respectively. Ambient NH 4 concentrations in the river were consistently below that predicted from excretion equations suggesting that microorganisms may have rapidly taken up much of the released ammonium. Downstream of the falls, epilithon biomass was over nine times more abundant, benthic invertebrate densities were approximately two times higher, and fish biomass was eight times greater compared to upstream. There were no upstream–downstream differences in substrate organic matter biomass. Fishes downstream of the falls had higher δ 13 C and δ 15 N values than biota upstream of the falls consistent with the anticipated effect of lake derived subsidies. Using stable isotopes values and a mixing model, we estimated that sucker eggs comprised 25–58% of the diet of stream fishes during the growing season. Suckers provided a large subsidy, greater than all other fishes, without mass mortality and significantly enhanced the productivity of the recipient river system. Stable isotopes revealed that subsidies were incorporated into the stream food web. Differences between salmon and sucker subsidies related to the type, magnitude, timing, and the life history of the donor highlight the potential importance of spawning migrations of adfluvial suckers, and other potamodromous fishes, in streams and rivers around the world.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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; both teacher heads agree on what is shown here.
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".