Distinguishing microplastics from microplastic-like particles in the marine fish from Qatar

Abstract Microplastic (MP) pollution poses a significant threat to marine ecosystems. This study assessed MP accumulation in the gastrointestinal tracts of 170 individuals from four commercially important fish species in Qatar along with their level of risk. MP-like particles were extracted via chemical digestion and density separation, and analysed using stereomicroscopy. Fibers were the dominant MP shape, with blue being the most common colour. The polymer composition of MP-like particles was further analysed using µ-Raman spectroscopy, which confirmed only 7 particles (4.12% of the total 170 fish samples) as MPs (> 70% match with polymer library databases). Polymer analysis confirmed the presence of polyethylene (PE) and polypropylene (PP) in the fish digestive tracts. The mean abundance was 0.070 ± 0.090 MPs/g of fish gut, a level relatively low compared to other regions of the Gulf and globally. The herbivorous Siganus canaliculatus ingested more MPs than the three carnivorous species, but this difference was not statistically significant (p > 0.05).