Polystyrene Microplastic Interferes with Yolk Reserve Utilisation in Early Nauplii.

Polystyrene microfragments are among the most common plastic pollutants globally. They significantly affect aquatic life, harming various organs and tissues. In this study, we examined the effects of 3 µm polystyrene beads (MPs, 20 µg/L) on development and yolk resorption in pre-feeding nauplii of , a lecithotrophic crustacean used in toxicity testing. Results showed a reduced hatching rate, slower growth, and the onset of oxidative stress. Histological analysis revealed no significant morphological alteration; however, yolk platelets lost N-acetyl galactosamine (galNAc), and resorption was delayed. Lectin staining also showed a reduction in N-acetyl glucosamine (glcNAc) in the gut brush border, indicating impaired gut function. Gas chromatography detected the release of nanogram amounts of toxic volatile compounds (VOCs, ethylbenzene, xylene, benzaldehyde, and styrene) into the culture medium. In conclusion, the data demonstrate a delay in larval yolk resorption that can likely be attributed to the release of VOCs, which induce oxidative stress. Further research is urgently needed, given the potential biological and ecological implications of this finding.