Characterization of microplastics in Thaisella chocolata from a southern Peruvian port

The marine coast is affected by significant amounts of primary and secondary microplastics (MPs). In the Port of Matarani, located in the department of Arequipa, southern Peru, activities such as fishing and shellfish harvesting are carried out. The objective of this study was to characterize the MPs in the marine snail Thaisella chocolata. A total of 150 T. chocolata individuals were collected from two zones. Zone A is located 100 meters from the pier at the Port of Matarani, where artisanal fishing boats are docked, and Zone B is a sea lion colony located approximately 2 kilometers from the pier. Collections were carried out during the winter and spring seasons of 2021. Snail tissue digestion was performed using 10% KOH, concentrated NaCl was used for MPs separation, and the samples were filtered. The MPs found were then identified and measured through microscopy, and their composition was determined by Raman microscopy. MPs were recorded in 100% of the collected snails. The most abundant forms were filaments > fibers > fragments. The dominant color was blue (53.94%), and the most frequent size range was 0.0825 to 0.1609 mm (45.9%). The highest abundance of MPs was found in winter and in female snails from Zone B (5.74 and 2.74 MPs/ind., respectively). No direct relationship was found between shell length and tissue weight of T. chocolata in relation to the amount of MP/ind. Raman microscopy identified the presence of PPO (poly(2,6-dimethyl-1,4-phenylene oxide)), PPSU (polyphenylsulfone), PDMS (poly(dimethylsiloxaneco-methylphenylsiloxane)), PBT (poly(butylene terephthalate)), PVBP (poly(4-vinylbiphenyl)), and PS (polystyrene). It is concluded that based on sex and season, the snail T. chocolata can be used as a bioindicator of MPs pollution, characterized by their shape, color, size, and chemical composition in the Peruvian coastal marine ecosystem.