Simulated heatwave and fishing stressors alter corticosteroid and energy balance in neonate blacktip reef sharks, <i>Carcharhinus melanopterus</i>.
Bibliographic record
Abstract
Abstract The increasing frequency and duration of marine heatwaves attributed to climate change threatens coastal elasmobranchs and may exacerbate existing anthropogenic stressors. While the elasmobranch stress response has been well studied, the role of the unique corticosteroid—1α-hydroxycorticosterone (1α-OHB)—in energy balance is not understood. Therefore, 1α-OHB’s utility as a stress biomarker in elasmobranch conservation physiology is equivocal. Here, we analyse the roles of corticosteroids, 1α-OHB and corticosterone, and metabolites, glucose and 3-hydroxybutyrate (3-HB), in response to stress in a protected tropical shark species, the blacktip reef shark (Carcharhinus melanopterus). Wild-caught neonates were exposed to ambient (27°C) or heatwave conditions (29°C) and subsequently a simulated fishing stressor (1 min air exposure). Blood samples were taken prior to temperature exposure, prior to air exposure, and 30 min, 1 h, 24 h, and 48 h post-air exposure at treatment temperatures. Plasma 1α-OHB was elevated for 48 h in 27°C-exposed sharks but declined over time in 29°C-exposed sharks. Plasma 1α-OHB was not correlated with either metabolite. Plasma glucose was higher and plasma 3-HB was lower in 29°C-exposed sharks. In a separate experiment, blood samples were collected from both neonate and adult sharks immediately following capture and again 5 min later, and analysed for corticosteroids and metabolites. Plasma 1α-OHB increased in neonates within 5 min, but neonates displayed lower plasma 1α-OHB and higher glucose concentrations than adults. We conclude that 1α-OHB does not serve as a classic glucocorticoid role in C. melanopterus under these stressors. Furthermore, we show for the first time, ontogenetic differences in plasma 1α-OHB. Ultimately, our findings provide insights into hormonal control of energy mobilization during stress in C. melanopterus, particularly during simulated heatwave conditions, which seem to alter both endocrine and energy mobilization. Further work is needed to determine the utility of 1α-OHB as a biomarker for the mobilization of energy during a stress event in elasmobranchs.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".