Styrene toxicity in the embryonic development of Celebes Medaka (Oryzias celebensis, Weber 1894): An assessment of the plastic monomer's impact.

The pervasive issue of plastic pollution poses a significant threat to aquatic ecosystems, with plastic monomers such as styrene presenting serious risks to fish development. This study examines the embryotoxic effects of styrene on Oryzias celebensis (Celebes medaka), focusing on key developmental stages. Sixty embryos at stage 17 (24 h post-fertilization, hpf) were exposed to styrene concentrations of 1, 5, 10, and 20 mg/L, alongside control groups treated with embryo rearing medium and 0.5 % ethanol. Developmental parameters, including egg diameter, yolk sac volume, yolk absorption rate, somite formation, heart function, hatching time, and larval morphology, were evaluated. Significant developmental disruptions were observed at styrene concentrations of 10 and 20 mg/L, including delayed somitogenesis, reduced cardiac function, and impaired jaw movement. Styrene exposure also resulted in morphological abnormalities such as craniofacial deformities, yolk sac edema, and spinal malformations. These findings reveal the vulnerability of aquatic embryos to styrene pollution, emphasizing its potential ecological consequences in contaminated habitats. The study underscores the importance of addressing plastic-derived pollutants to safeguard marine biodiversity.