Seasonal change of microplastics uptake in the Pacific oysters Crassostrea gigas cultured in the Yellow Sea and Bohai Sea, China

This study investigated seasonal microplastics (MPs) pollution characteristics in oysters and surrounding surface seawater from five aquaculture farms located at the Yellow Sea and Bohai Sea. MPs abundances in oysters were 2.40 ± 0.14 (winter) to 3.28 ± 0.19 (autumn) items/individual, and 0.22 ± 0.02 (spring) to 0.45 ± 0.06 (summer) items/g (ww). In surface seawater, average seasonal MPs abundances were 3.41 ± 1.06–8.86 ± 2.48 items/L. Fibers were dominant shape, and cellophane and polyethylene terephthalate (PET) were dominant polymers in oysters and surface seawater. Positive correlation was found between oysters' MPs abundance (items/individual) and environmental factors (NO2-N (r = 0.466), and temperature (r = 0.485)) by Spearman correlation analysis in four seasons. Main environmental factor affecting seasonal MPs abundance of oysters and surface seawater was NH3-N and SiO3-Si in summer and winter respectively. In conclusion, seasonal change of MPs uptake in cultured oysters was relatively small. [Display omitted] •The average seasonal MPs abundance of oysters was 2.40–3.28 items/individual.•Fibers were the most predominant shape in both oysters and surface seawater.•Both of the abundances of MPs in oysters and surface seawater were low in spring.•MPs abundance in oysters was positively related to environmental factors of sea water.