Marine nutrient transport: anadromous fish migration linked to the freshwater amphipod Gammarus fasciatus
Bibliographic record
Abstract
Migrating anadromous fish may transfer marine-derived nutrients to oligotrophic tidal fresh water. River herrings (genus Alosa Linck, 1790) are the dominant anadromous genus in Virginia, USA. This study investigates whether marine nutrients derived from spawning Alosa spp. were incorporated into benthic invertebrates by using the stable isotopes of carbon and nitrogen. Spawning Alosa spp. had higher δ13C and δ15N values (–18.5‰ and 13.9‰, respectively) than resident freshwater omnivorous fishes (–25.7‰ and 11.8‰, respectively). In a tidal stream supporting abundant spawning Alosa spp., 13C and 15N enrichment was observed in stream amphipods (Gammarus fasciatus Say, 1818) coincident with the spawning migration of Alosa spp. The δ13C value for G. fasciatus increased from –28.5‰ to –26.0‰ from early to late April then fell to –28.1‰ in early June. A similar trend was observed in mayflies (Heptageniidae). Particulate organic matter and sediments from both streams remained depleted in 13C (between –29‰ and –28‰) and 15N (between 0.5‰ and 3.0‰) during the spawning run of Alosa spp. It is estimated that between 5% and 35% of amphipod biomass may be derived from marine carbon brought to tidal fresh water by spawning Alosa spp.
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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 | 0.000 |
| 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) | 0.001 | 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".