Microplastics in wild freshwater fish of different feeding habits from Beijiang and Pearl River Delta regions, south China

Microplastic pollution is a major global challenge and a severe threat to aquatic organisms. The Pearl River Basin is the most important river system in Guangdong Province, China. As the second largest tributary of the Pearl River Basin, the Beijiang River flows through many cities in Guangdong Province and eventually merges into the Pearl River Delta. The goal of this research was to explore the microplastic pollution problem in the Beijiang River and Pearl River Delta. In total, 26 surface water and 47 wild freshwater fish samples from the Pearl River Delta and the main runoff area of the Beijiang River were collected. The average abundance of microplastics in surface water samples from the Beijiang River was 3183 items/m³, and the average abundance in fish samples was 5.6 items/individual; the values for the Pearl River Delta were 7571 items/m³ and 4.8 items/individual. In all samples, fibers and fragments were the major microplastic contaminants, most were white in color, and most were <1 mm in size. The microplastic abundance in carnivorous fish samples in the Beijiang River and Pearl River Delta was 3.5 and 3 items/individual, respectively, and omnivorous fish samples had 6.8 and 6.2 items/individual, respectively. Thus, the microplastic abundance in omnivorous fish samples was about twice that of the carnivorous fish. These results reveal the quantity of microplastic pollution in the Beijiang River and the Pearl River Delta and provide an important basis for further study of microplastics in the freshwater ecosystem of the Pearl River Basin.