Observation of microplastics in mariculture water of Longjiao Bay, southeast China: Influence by human activities

The fishery and mariculture industry contributes to social food supply and offers high-quality protein to humans. However, mariculture is recently regarded as an important source of marine microplastic pollution, which might even pose a threat to human health. Here we investigated a shrimp-culturing farm for 9 months in Longjiao Bay, a typical mariculture area in southeast China, to study the occurrence and seasonal variations of microplastics in the mariculture water. Results showed that microplastics were widely present (250–5150 particles/m3, mean 1594 particles/m3) in the water of culture ponds. Granules (41.36%) and fibers (34.93%) were the main components of microplastics and white (45.42%) is the dominant color, followed by yellow (32.13%) and black (19.55%). Most of microplastics had a particle size between 0.30 mm and 5.00 mm (92.03%). The proportions of PE (34.40%) and PET (30.18%) accounted for more than 60% of detected microplastics. The abundance of microplastics in mariculture water had a potential positive correlation with local seafood yield and a negative correlation with land areas. This study suggested that further research is needed to figure out the impact of the high levels of microplastic abundance in mariculture environments on organisms, especially cultured ones. •Based on 9 months of survey, microplastics are commonly present in the mariculture water of shrimp-culturing ponds.•Aging and breaking of mariculture pond itself and fishery equipment were the main sources of microplastics.•The change of microplastics abundance roughly coincided with that of shrimp culture that means potential food safety risk.•The abundance of microplastics in seawater had a potential positive correlation with the local seafood yield.