Impact of co-exposure to Chaetoceros spp. and Tenacibaculum maritimum on Atlantic salmon (Salmo salar) gills
Bibliographic record
Abstract
Fish gills play a critical role in both respiration and immune defense, but they are also prone to diseases such as complex gill disease (CGD), particularly in aquaculture settings. Environmental stressors, including harmful algal blooms (HABs), can inflict significant damage to gills, leading to hypoxic conditions that compromise fish health. Additionally, bacterial pathogens such as Tenacibaculum maritimum are responsible for considerable gill pathology and pose substantial economic challenges in marine fish farming. This study aims to explore the interactions between environmental stressors and immune responses in Atlantic salmon. The hypothesis posited that exposure to Chaetoceros spp. would damage the gills and impact responses to Tenacibaculum infections. Atlantic salmon (∼300 g, n = 500) were kept in 21 tanks in 2 saltwater systems (A: 9; B: 12). Fish in systems A and B were exposed to Chaetoceros spp. (1000 cells/ml) at intervals of 1, 3, and 5 days or just once on day 5, alongside a PBS (Sham) control group. In system B, fish were challenged with T. maritimum (2.92 × 10 6 CFU/mL) after exposure to Chaetoceros spp. in 6 tanks. Gill samples were collected prior to exposure, 6, 9-, 15-, and 35-days post-exposure (dpe) for immunological analyses. For histological analysis samples were collected at 1, 2, 7, 10- and 37 dpe. Additionally, serum amyloid A and cortisol levels in serum and fecal samples were assessed. Mortality in System B was 30 %, occurring mostly within 10 to 21 days. Exposure to Chaetoceros spp. significantly reduced mmp9 expression; however, no other genes were significantly affected, despite observed mortality and skin/mouth lesions in fish. Lamellar congestion and necrosis were non-remarkable in histological analysis. Fish exposed to Chaetoceros spp. exhibited higher scores for hemorrhage and necrosis, although these differences were mild and not statistically significant. Serum cortisol was significantly higher in the Chaetoceros -challenged group at 2 dpi ( p = 0.002). Fecal cortisol levels decreased significantly in the Chaetoceros -challenged group ( p = 0.0276), while no significant differences were found for serum amyloid A ( saa ) compared to Sham controls at 2 dpi. As a result of this experimental exposure, the findings indicated that, despite the histological gill damage, the induction of immunological gene expression, and mortality were minimal. Successful infections were confirmed in both systems, and some level of immunophysiological induction was detected in exposed fish. Further research involving different species of Chaetoceros with Tenacibaculum could provide more insights into their roles in the development of CGD.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".