Nanoparticles decrease the byssal attachment strength of the thick shell mussel Mytilus coruscus.

The extensive application of nanoparticles (NPs) drives their release into the ocean, which may pose a potential threat to marine organisms. Although the byssus is important for the survival of mussels, the effects of NPs on byssal attachment and the underlying molecular byssal responses remain largely unknown. Therefore, the impacts of three metal oxide NPs (nTiO, nZnO, and nFeO) on the production and mechanical properties of byssal thread in the thick shell mussel M. coruscus were investigated in this study. The results showed that both mechanical properties (such as strength and extensibility) and morphology (diameter and volume) of byssal thread newly produced by M. coruscus were significantly affected after NP exposure, which resulted in an approximately 60-66% decrease in mussel byssal attachment strength. Downregulated expression of genes encoding mussel foot proteins, precursor collagen proteins, and proximal thread matrix proteins was also detected in this study, and this alteration may be one of the reasons for the weakened mechanical properties of byssal threads after NP exposure. This study indicated that NP pollution may hamper byssal attachment of M. coruscus and thereby pose a severe threat to the health of mussel individuals and the stability of the intertidal ecosystem.