The estuarine fish community and food web structure in areas of sea lettuce (Ulva lactuca) and eelgrass (Zostera marina) within the Stanley River Estuary, Prince Edward Island
Bibliographic record
Abstract
Agriculture is a major industry on Prince Edward Island (PEI), covering approximately 44% of the land area. Large quantities of nutrients from artificial fertilizers are entering surface and ground waters that feed estuaries and bays, replacing eelgrass (Zostera marina) with dense blooms of sea lettuce (Ulva lactuca) and resulting in anoxic events. This project aimed to determine whether the nearshore estuarine fish community and food web structure differed between areas dominated by sea lettuce and areas with mainly eelgrass. Monthly beach seining was conducted from April to August 2008 to sample the fish community at five stations in the Stanley River estuary on PEI, where habitat varied from primarily eelgrass beds at the downstream stations to complete sea lettuce cover at the upstream stations. The fish community differed significantly among stations and months. In general, stations with large quantities of sea lettuce had fewer Atlantic silverside (Menidia menidia) and more mummichog ( Fundulus heteroclitus) than those with less sea lettuce in April, more ninespine stickleback (Pungitius pungitius) and fewer northern pipefish (Syngnathus fuscus) in June, and more young-of-the-year (YOY) Gasterosteus spp. and YOY fourspine stickleback ( Apeltes quadracus), yet fewer northern pipefish, in July. In August, the main differences were fewer YOY Atlantic silverside and YOY northern pipefish and more YOY mummichog at the upstream sea lettuce stations. In addition, primary producer, invertebrate, and fish samples were collected at the same five stations in August 2007, as well as monthly from April to August in 2008, in order to assess temporal and spatial variability in the food web structure. The food web was described using carbon and nitrogen stable isotope analysis and stomach contents analysis was performed on two common fish species, mummichog and fourspine stickleback. Overall, stable isotope values did not differ between fish caught at sea lettuce and eelgrass stations. This indicated that there was no shift from a pelagic (lower δ13C values) to a benthic-driven (higher δ13C values) food web at stations with an abundance of sea lettuce and, presumably, associated benthic invertebrates. Gammarid amphipods were by far the most prevalent food item for mummichog and fourspine stickleback. Except in April, there were no significant differences in mummichog diet between sea lettuce and eelgrass stations. While increased sea lettuce alters the structural habitat of an estuary, and potentially increases the abundance of some invertebrates, this does not result in fish having a larger proportion of their diet corning from benthic resources.
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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".