Non-lethal analysis of F2-isoprostanes in the epidermal mucus of freshwater fish species as an indicator of diluted bitumen toxicity
Bibliographic record
Abstract
Canada is among the world’s leading producers and exporter of diluted bitumen (dilbit). Despite this, there is a lack of understanding surrounding the effects of dilbit spills in freshwater ecosystems. F2-isoprostanes (F2-IsoPs) are reliable biomarkers of oxidative stress, one of dilbit’s toxicity pathways in fish, however they are seldom studied in fish. This thesis describes the development of a non-invasive method for measuring F2-isoprostanes in the epidermal mucus of fish to measure oxidative stress in fathead minnows (Pimephales promelas) exposed to dilbit. An HPLC-MS/MS method was first developed and validated using Northern pike mucus (Esox lucius), and used to successfully detect F2-IsoPs in lake trout (Salvelinus namaycush) angled at the IISD-Experimental Lakes Area in Northwestern Ontario, proving these compounds are present at detectable concentrations in wild fish mucus. The relative concentrations of F2-IsoPs were then examined in tissues of rainbow trout (Onchorynchus mykiss) exposed to acute physical stress. F2-IsoP concentrations were also compared to total glutathione (GSH) and the GSH redox status in this study, finding a possible link between F2-IsoPs and GSH in gills and evidence of a mild oxidative stress response in physically stressed trout. The effect of dilbit on epidermal mucus and liver F2-IsoP concentrations was then examined in juvenile fathead minnows exposed for 7 days to 0-30% dilbit solutions, or water accommodated fraction (WAF). F2-IsoP concentrations did not differ significantly between any dilbit treatments: however this lack of response may have been caused by low uptake of polycyclic aromatic compounds. Liver and mucus F2-IsoPs were positively correlated in the control group and negatively correlated in the 30% WAF treatment. Finally, the developed method was field-tested in the Freshwater Oil Spill Remediation Study (FOReSt), a collaborative project aiming to determine the fate and behaviour of dilbit in a freshwater shoreline environment. Adult fathead minnows were exposed to environmentally relevant concentrations of weathered dilbit for ~75 days in shoreline enclosures at the IISD-ELA. Mucus F2-IsoPs were quantified in fathead minnows and finescale dace (Phoxinus neogaeus). Concentrations were not significantly different between treatments, suggesting dilbit exposure did not cause a lasting oxidative stress response in either species.
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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) | 0.001 | 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".