Quantification and characterization of microplastics in an intertidal gastropod the common periwinkle Littorina littorea

Marine microplastics (MPs) are an increasingly important concern worldwide. This study aimed to investigate the occurrence and characteristics of microplastics in an intertidal sea snail, the common periwinkle ( Littorina littorea ) sampled from Saint Martin's Island, Bay of Bengal. The results revealed that 100% of the common periwinkle snails ingested microplastics (MPs), with a mean abundance ranging from 2.63 ​± ​1.07 to 23.89 ​± ​3.53 ​MP/g (average: 7.76 ​± ​5.77 ​MP/g). Microplastic particles in the 100–1500 ​μm size class were the most abundant (63%), whereas black and red fibers were the most abundant colors and shapes. Polypropylene (PP, 34%) and polyethylene (PE, 38%) were the major polymer types, followed by polystyrene (PS, 15%) and polyethylene terephthalate (PET, 13%). Although the polymer hazard index (PHI) showed risk categories III to IV due to highly hazardous polymers such as PS and PE in the soft tissue of the common periwinkle snails, the pollution load index (PLI <10) revealed minor contamination across the sampling site of Saint Martin's Island. Gastropod feeding patterns and food items impacted MP abundance in the studied area. • Mean abundance of MPs ranged from 2.63 ​± ​1.07 to 23.89 ​± ​3.53 ​MP/g. • Black and red fibers within 100–1500 ​μm were the most abundant MPs. • Polypropylene (34 ​%) and polyethylene (38 ​%) were the major polymers. • Polymer hazard index showed risk categories III (high) to IV (danger). • Common periwinkle could be used as a bioindicator of MP pollution.