Simulated heatwave and fishing stressors alter corticosteroid and energy balance in neonate blacktip reef sharks, Carcharhinus melanopterus.

Abstract The increasing frequency and duration of marine heatwaves attributed to climate change threatens coastal elasmobranchs may exacerbate existing anthropogenic stressors. While the elasmobranch stress response has been well studied, role unique corticosteroid—1α-hydroxycorticosterone (1α-OHB)—in energy balance is not understood. Therefore, 1α-OHB’s utility as a biomarker in conservation physiology equivocal. Here, we analyse roles corticosteroids, 1α-OHB corticosterone, metabolites, glucose 3-hydroxybutyrate (3-HB), protected tropical shark species, blacktip reef (Carcharhinus melanopterus). Wild-caught neonates were exposed ambient (27°C) or heatwave conditions (29°C) subsequently simulated fishing stressor (1 min air exposure). Blood samples taken prior temperature exposure, 30 min, 1 h, 24 48 h post-air exposure at treatment temperatures. Plasma was elevated for 27°C-exposed sharks but declined over time 29°C-exposed sharks. correlated with either metabolite. higher plasma 3-HB lower In separate experiment, blood collected from both neonate adult immediately following capture again 5 later, analysed corticosteroids metabolites. increased within displayed concentrations than adults. We conclude that does serve classic glucocorticoid C. melanopterus under these Furthermore, show first time, ontogenetic differences 1α-OHB. Ultimately, our findings provide insights into hormonal control mobilization during melanopterus, particularly conditions, which seem alter endocrine mobilization. Further work needed determine event elasmobranchs.