Impacts of phenanthrene on juveniles of dusky grouper, Epinephelus marginatus (Perciformes: Serranidae): Behavioral, endocrine and oxidative effects.

Phenanthrene (PHE), a polycyclic aromatic hydrocarbon (PAH), poses significant risks to marine biota, yet its behavioral and physiological effects on fish, particularly on Epinephelus marginatus, remain poorly understood. This study therefore aimed to assess the acute (96 h) effects of PHE exposure (0.1 and 1 mg L⁻¹) on juvenile E. marginatus (n = 15 per treatment) compared to an ethanol control (0.004 %). Behavioral endpoints, oxidative stress biomarkers, plasma cortisol levels, and acetylcholinesterase activity were evaluated in the same individuals. PHE-exposed fish exhibited pronounced behavioral disturbances, including reduced agonistic interactions and loss of equilibrium at the highest concentration, which may compromise social hierarchy and predator avoidance. Although acetylcholinesterase and antioxidant enzymes remained unchanged, the higher PHE concentration triggered increased plasma cortisol and hepatic lipid peroxidation, indicating stress axis activation and oxidative damage. These results provide the first integrated evidence of neurobehavioral and physiological disruption in E. marginatus under PHE exposure.