Characteristics Of Microplastics In Fish From Coastal And Fresh Waters Of China

Plastic pollution is a growing global concern because of its occurrence in aquatic systems and interaction with aquatic fauna.The objectives of the present study were to investigate the plastic pollution in fishes from coastal and fresh waters of China and to reveal the effects of different types of raw microplastics on fish under laboratory conditions.Microplastics(MPs)were abundant in the gastrointestinal tract(GIT)of sea fish species and varied from 1.1 to 7.2 items by individual.Thamnaconus septentrionalis contained the highest abundance of MPs(7.2 items/individual).Fiber,fragment,pellet,sheet and film were found in fishes.The size of microplastics and mesoplastics ranged from 0.04 mm to 5 mm and 5.1 mm to 24.8 mm,respectively.The abundance of plastics by items/individual was significantly higher in sea demersal fishes than that in pelagic fishes(p < 0.05).The proportion of plastics in the stomach to the intestines showed great variation in different species.The plastics were dominanted by fiber in shape,transparent in color and cellophane in composition in fishes from coastal waters.In this study plastic pollution was investigated in six fish species from Taihu Lake.MPs varied from 1.8 to 3.8 by items/individual and the highest abundance of MPs was found in Hypophthalmichthys molitrix(3.8?2.0 items/individual).Only three morphotypes were found and fibers were the most common.MPs were accounted for 76.2% of total plastic,and ranged from 0.19 mm to 5 mm in size.The dominant plastics were transparent among six colors.Mosquito fish(Gambusia affinis)was selected as an indicator species and sampled from seven different river systems in Shanghai.The abundance of MPs varied from 0.4 to 1.1 items/individual and the highest abundance was found in fish from site 5.Fragment was dominant by type,and size of microplastics ranged from 0.02 mm to 4.8 mm.The most common size was < 0.1 mm(53.2%).Black color was dominant.Significant difference was found in the abundance of MPs/individual fish between different sites(p<0.01).Goldfish(Carassius auratus)were exposed to three types of raw MPs material types and shapes for six weeks.No mortality was observed.Only fibers were ingested by fish but not likely to be accumulated in the GIT.The highest percentage of fish was affected by fragments and damaged the jaws.Pronounced and severe damages were found in the liver of fish exposed to fibers-based food.The distal intestine showed more pronounced and severe changes compared to the proximal intestine due to intake of fibers in food.The ingestion of fiber caused highest frequencies of progressive and inflammation changes in the liver and intestine in fish.This is in accordance with the higher organ index in liver and proximal intestine than other groups.Due to chewing process,damages in the jaws were observed from slight exfoliation to deep incisions in fragment-and pellet-based groups.The highest frequency of regressive and circulatory(such as dilated sinusoids)changes were found from the fragment group in upper and lower jaw,and in lower jaw and liver,respectively.In conclusion,the ingestion of plastics by fish was closely related to the habitat and GIT structure.It is highly recommended that the entire gastrointestinal tract and digestion process be used in future investigations of plastic pollution in fish.Ingestion and chewing of MPs-based food lead to various levels of damages in the respective organs,suggesting that different types of plastics can have totally different morphological and histochemical impacts on fish.This study provides base line information about plastic pollution in fishes from China and contributes towards wider understanding of emerging issue of plastic pollution.