Ecology of lesser scaup amphipods in the upper-Midwest: scope and mechanisms of the Spring Condition Hypothesis and implications for Migration Habitat Conservation
Bibliographic record
Abstract
I tested the scope of the Spring Condition Hypothesis in explaining the continental population decline of lesser scaup (Aythya affinis; hereafter scaup) and explored potential mechanisms affecting female body condition to assist conservation efforts for population recovery. Lipid reserves of females currently are lower than historical values during spring migration throughout Iowa, Minnesota, and North Dakota; females catabolized lipids throughout this area (indexed by concentrations of plasma-lipid metabolites, which accounted for 75% of the variation in mass change). My results indicate that a large segment of the continental scaup population likely is affected by decreased lipid reserves, which could cause reductions in breeding propensity and reproductive success. Hepatic cadmium was negatively correlated with lipid reserves of females during spring migration; however, current cadmium concentrations only accounted for 11% of the observed decrease in lipid reserves of females between Illinois and Minnesota. Wetland use by scaup was positively correlated with amphipod densities throughout the upper-Midwest, indicating a preference for amphipods. Amphipod densities were markedly lower (1 - 12 m-3) and scaup were consuming fewer amphipods in the upper-Midwest relative to historical records. Scaup probably must spend more time searching for food within and among wetlands than they did historically. Fish occurred in 74, 78 - 84, and 31 - 45% of wetlands in Iowa, Minnesota, and North Dakota, respectively, whereas historically they occurred in only 10 - 20% of wetlands. Amphipod densities were negatively correlated to fish densities and sedimentation. My results indicate that there has been a decrease in amphipod densities throughout the upper-Midwest, which likely is causing the observed decreases in lipid reserves of scaup. My results generally were consistent with the Spring Condition Hypothesis and indicate that wetland restoration efforts are needed throughout the upper-Midwest, but especially in Iowa and southern Minnesota. Managers should provide abundant populations of amphipods (over 26 m-3 geometric mean across the landscape) and target wetlands that: (1) have large (> 500 m diameter) open-water zones, (2) are deep enough to support over-wintering populations of amphipods, (3) allow management of fish communities, and (4) the surrounding land can be managed to reduce sedimentation.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 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".