Polyethylene terephthalate microfibers change molting patterns of Penaeus vannamei in a benthic exposure system

Crustaceans inhabiting benthic environments come into contact with microplastics (MPs) that accumulate on the seafloor. At present, research on the toxicity of MPs to crustaceans has mainly focused on spherical MPs. Hence, this study assessed the toxicity of polyethylene terephthalate microfibers (PET MFs) to crustaceans. The whiteleg shrimp (Penaeus vannamei), a valuable food source, was exposed to PET MFs for 21 d, and their biological responses at the individual, tissue, and molecular levels were observed. The results revealed that PET MFs negatively affected the overall health (body length and weight), altered the molting cycle, burrowing movement, and caused changes in the body shell, hepatopancreas, and intestinal ultrastructure. By analyzing modifications in transcriptomes and metabolites, we revealed alterations in molting hormones and chitin biosynthesis-related molecules, which induced adjustments in the molting cycle. Our study enhances the understanding of marine crustaceans' responses to MFs, highlighting the changes in biological mechanisms.