Transfer of Poly(methyl methacrylate) Nanoparticles from Parents to Offspring and the Protection Mechanism in Two Marine Invertebrates

Ingested nano- and microplastic particles are observed to cause significant health impacts in several animal models. In this study, we investigate the nanoplastic particle transfer from exposed adults to offspring using the marine calcareous tubeworm Spirobranchus bakau and the acorn barnacle Amphibalanus amphitrite as model organisms. Adult tubeworms and barnacles were exposed to blue fluorescent poly(methyl methacrylate) (PMMA) nanoparticles at 10 mg/L concentration for 12 and 25 days, respectively, under controlled environmental conditions. PMMA nanoparticles used in the exposure experiments had a hydrodynamic size of 167.7 nm when dispersed in ultrapure water (DLS), a dry size of 106.4 nm (SEM), and a zeta potential of −28.4 mV. PMMA particles were found on the membrane of sub-mantle tissues in adult barnacles but not in the oocytes or developing embryos of barnacles. On the other hand, PMMA nanoparticles were observed inside the eggs of tubeworms. After fertilization, these PMMA nanoparticles were gradually released from the developing embryos via exocytosis, and no PMMA particles were observed inside the trochophores 24 h post-fertilization. In addition, the PMMA nanoparticles present during early developmental stages of the tubeworm eggs did not affect trochophore development or subsequent settlement. Based on the two model species tested, the results suggest that the protective mechanisms preventing transfer of nanoparticles of common plastics from parents to offspring could differ among animal species and that the choice of the animal model and the size of polymer nanoparticles selected can significantly impact the outcome of the study.