A territory-wide study of microplastics in barnacles of Hong Kong

Microplastic pollution is an emerging problem in the marine environment and assessment of microplastic abundance in wild organisms is essential for risk assessment. The occurrence of microplastics in barnacles Amphibalanus amphitrite, Tetraclita japonica japonica and Capitulum mitella was determined for 30 sites, including rocky shores, sandy shores and mudflats. The mean number of microplastic abundance ranged from 0.26 to 10.26 items g^-1 of body wet weight, or from 0.13 to 1.72 items individual^-1 with fibers being the most abundant type of microplastics. The chemical composition of 152 pieces of potential microplastics was analysed using micro-Fourier transform infrared spectroscopy (µ-FTIR). Fifty two of them were synthetic polymers (45 fibers, 6 fragments and 1 bead), 95 natural cotton fibers and five unknown. Eight types of polymer were identified with cellophane being the most abundant (58%). Compared with animals from other taxonomic groups, the problem of microplastic ingestion was relatively minor in barnacles.