Microplastics in the Euphrates: Assessing contamination in water, sediment, and commercial fish species

Microplastics (MPs) are increasingly recognized as emerging pollutants in freshwater ecosystems, with implications for ecological integrity and food safety. This study presents the first integrated assessment of MP contamination in the Euphrates River (Türkiye), focusing on water, sediment, and six commercially important fish species. We hypothesized that MP abundance in fish would vary according to species-specific feeding behavior and habitat use. To test this, sampling was conducted at 23 sites encompassing urban, agricultural, and industrial zones. MPs were identified and quantified using stereomicroscopy and Fourier-transform infrared spectroscopy. MPs were detected in 52.2 % of water samples (0-6.6 MP/m) and 43.5 % of sediment samples (0-15 MP/kg), with fibers and polyethylene terephthalate were the dominant forms. Among fish species (Capoeta trutta, Carasobarbus luteus, Cyprinus carpio, Cyprinion macrostomus, Chondrostoma regium, and Carassius gibelio), MP abundance ranged from 0.2 to 1.76 MPs/individual. Contrary to our initial hypothesis, MP loads did not significantly differ among species or locations. Moreover, statistical analyses revealed no significant associations between MP ingestion and fish traits such as age, length, or weight. However, relatively high MP levels were observed in C. trutta, possibly reflecting its benthopelagic habitat and omnivorous diet. These findings point to a diffuse and widespread pattern of MP contamination, likely driven by multiple anthropogenic sources and hydrodynamic factors. The study underscores the need for targeted pollution control strategies and highlights the ecological vulnerability of the Euphrates River.