Deposition characteristics of microplastics in coral reef fish with different feeding habits from the Xisha Islands Waters, South China Sea

Over the past decade, awareness of plastic pollution has significantly increased, leading to a focus on its potential adverse effects on biota, including the ingestion of microplastics by fish. This study investigates the abundance, composition, and characteristics of microplastics in the gills and gastrointestinal tracts (GITs) of 96 coral reef fish with different feeding habits (herbivorous fish: Scarus rivulatus, Naso lituratus, and Acanthurus triostegus; omnivorous fish: Abudefduf vaigensis; carnivorous fish: Epinephelus merra) from the Xisha Islands Waters, South China Sea. The relationships between microplastic abundance and fish length, weight, and feeding habits were also analyzed. Results show that 97.92% of the sampled coral reef fish contained microplastics. The average abundance of microplastics in the gills and GITs was 1.09 ± 0.25 items individual and 1.74 ± 0.26 items individual, respectively. The predominant shapes of microplastics were fibers, with black and blue being the most common colors. Most microplastics (90%) were smaller than 1 mm, and the main polymer types were PET, CP, PE, and PP. Additionally, the GITs contained more microplastics than the gills. Unlike the scope of previous studies, this study newly found the following two points: 1.Herbivorous fish had higher microplastic content than omnivorous fish, while carnivorous fish had the lowest, likely due to herbivorous fish feeding primarily on microplastic-polluted coral reefs. 2.The abundance of microplastics in the gills and GITs was not related to gill weight or GITs weight, however, the abundance of microplastics was significantly correlated with fish body length and body weight.