Challenges for Diadromous Fishes in a Dynamic Global Environment
Bibliographic record
Abstract
Abstract.-While there has been much recent research conducted on the effects of semelparous anadromous (sea-run) fishes on nutrient cycling and productivity in freshwater lakes, we know very little about how iteroparous anadromous fishes may affect these processes and ecosystems. Although iteroparous sea-run fishes do not contribute mass postspawning carcass additions to freshwater systems, nutrients may still be transported from marine to freshwater environments through deposition of eggs, metabolic losses, and postspawning/overwintering mortality. As well, some iteroparous sea-run species spend significant time growing to juvenile and smolt stages in freshwater where they may affect top-down or bottom-up changes in food web structure. The goals of this study were to (1) conduct a preliminary investigation into the effect of sea-run Arctic char Salvelinus alpinus on food web structure in coastal lakes in the central Canadian Arctic, and (2) semiquantitatively assess the direction of net nutrient transport achieved by anadromous Arctic char during annual migrations to the sea. In 2006, fishes and macroinvertebrates were collected from four lakes near Hope Bay, Nunavut, and analyzed for stable C, N, and S isotopes to examine food web structure and anadromy. Preliminary results indicate that the presence of sea-run Arctic char may impact the ?15N-determined trophic position and condition of sympatric populations of lake trout S. namaycush. When stable S isotope results were applied to a two-source mixing model, marine food items accounted for 84-100% of the diet of mature, anadromous Arctic char. A semiquantitative assessment of char-mediated nutrient transport between marine and freshwater environments at Nauyuk Lake, Nunavut, indicated that masses of nutrients imported by char to freshwater systems are likely negligible in relation to ambient water chemistry. There was significant among-year variability in the magnitude and direction of nutrient transport, and the complex life history of anadromous Arctic char requires more research before detailed nutrient budgets can be calculated.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.003 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.001 | 0.004 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.012 | 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; 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".