Microplastic Ingestion by Fish with Different Feeding Habits from Different Habitats in a Typical Semi-Enclosed Haizhou Bay

Microplastic (MP) pollution has spread from the mainland to the ocean. However, Haizhou Bay, which is one of the important land-ocean transition zones, has been reported relatively little about the enrichment of MPs. To provide fundamental data for MP pollution in Haizhou Bay, we studied the occurrence of microplastics in the intestines of 8 species of fish with different habits and feeding modes. The fish intestines were digested with a 10% KOH solution, and MPs are separated with a glass fiber filter. Then, the size, shape, color, and composition of the MPs were analyzed using a stereomicroscope and Fourier transform infrared spectrometer. The results showed the abundance of MP intake ranged from 0.02 items g⁻¹ to 0.16 items g⁻¹ and the detection rate of MPs ranged from 53.33% to 80% across different fish species. The MP intake in benthic fish and omnivorous fish was significantly higher than that of pelagic fish and predatory fish. Smaller MPs (< 0.25 mm) were the dominant types and accounted for 62.50% of the total. The fiber was the prevailing shape of MPs, and the black MPs were the most common, followed by red and yellow ones. Polyethylene terephthalate (PET), polyamide (PA), and polystyrene (PS) were the main components of MPs, accounting for 34.9%, 29.9%, and 16.4%, respectively. According to the composition analysis of MPs, the main sources of MPs in fish of Haizhou Bay were attributed to marine aquaculture and port construction. The results are helpful for our better understanding of the status of MP pollution in this area, and further aid in the development of the pointed measures to mitigate and prevent the MP pollution in this ecologically important area.