Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Observation of microplastics in mariculture water of Longjiao Bay, southeast China: Infuence by human activities Bin Chen a , Yingping Fan b,c , Wei Huang d , A.B.M. Sadique Rayhan a , Kai Chen a,c,e, ⁎ , Minggang Cai a,c,e,f, ⁎ a Coastal and Ocean Management Institute, Xiamen University, Xiamen 361102, China b College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan 316022, China c Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen 361102, China d Laboratory of Marine Ecosystem and Biogeochemistry, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China e College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China f State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen 361102, China ARTICLE INFO Keywords: Microplastic Seawater Trend Mariculture environment Longjiao Bay ABSTRACT The fshery and mariculture industry contributes to social food supply and ofers 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/m 3 , mean 1594 particles/m 3 ) in the water of culture ponds. Granules (41.36%) and fbers (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 fgure out the impact of the high levels of microplastic abundance in mariculture environments on organisms, especially cultured ones. 1. Introduction Microplastics refer to plastic particles with a diameter less than 5 mm (Thompson et al., 2004). Due to its high mobility, persistence and the sorption capacity of toxic organic pollutants in the ocean, studies on the impact of microplastics in the marine ecosystem have attracted increasing attention (Al-Thawadi, 2020; Alimi et al., 2018; Andrady, 2011; Galloway et al., 2017; Hüfer et al., 2017). Recent researches shown that microplastics are widely presented in daily food, especially in seafood (De-la-Torre, 2020; EFSA CONTAM Panel, 2016; Hantoro et al., 2019; Mercogliano et al., 2020; Santillo et al., 2017; Seltenrich, 2015; Smith et al., 2018; Walkinshaw et al., 2020). After the ingestion by cultured or wild aquatic organisms, microplastics would enter the food chain, and eventually pose a threat to human health (Chang et al., 2020; Prata et al., 2020; van Raamsdonk et al., 2020; Zhang et al., 2020). Seafood products have been an important food source with high protein and nutrition for a long time, becoming more and more popular among consumers today (FAO, 2018). So far, mariculture is one of the most important resource-saving ways to supply seafood worldwide. According to the data from the Food and Agriculture Organization of the United Nations (FAO), mariculture provided about 26.57% of the total global seafood product in 2016 (FAO, 2018), among which China consumed 62% of the total amount, and its mariculture industry has experienced fast growth due to huge domestic demand (FAO, 2018). From 2014 to 2018, mariculture product in China increased from 17.32 to 20.31 million tons (China Fishery Statistical Yearbook, 2019). Water quality is a basic issue for the development of the mariculture industry, while the current fshery activities have caused many en- vironmental problems (Edwards, 2015). Plastic pollution is one of the emerging problems with increasing concern of the public, as the direct sources of plastic debris like fshing nets, buoyancy materials and cages are essential equipment for mariculture. These plastic products could be broken into microplastics by long-term solar radiation, wind, wave https://doi.org/10.1016/j.marpolbul.2020.111655 Received 31 May 2020; Received in revised form 26 August 2020; Accepted 5 September 2020 ⁎ Corresponding authors at: Coastal and Ocean Management Institute, Xiamen University, Xiamen 361102, China. E-mail addresses: kchen@xmu.edu.cn (K. Chen), mgcai@xmu.edu.cn (M. Cai). Marine Pollution Bulletin 160 (2020) 111655 Available online 17 September 2020 0025-326X/ © 2020 Elsevier Ltd. All rights reserved. T