Investigation of the presence of microplastics in the stomach contents of fish from different trophic status that lives in different habitats

Rapid industrialization and excessive consumption of plastic products have resulted in tons of plastic waste accumulating in the environment. Pollution caused by microplastics (MPs) is an emerging environmental menace for ecosystems and for humanity. Information on the occurrence of microplastic (MP; particles smaller than 5 mm) in freshwater biota in the Türkiye is limited. In this study, the microplastic contaminations of seven fish species (Cyprinus carpio, Carassius gibelio, Alburnus spp., Scardinius erythrophthalmus, Vimba vimba, Neogobius fluviatilis, and Perca fluviatilis) collected from Lake Manyas, Lake Uluabat, Lake Gala, Lake Gökgöl, Alaçatı Dam, Beydağ Dam, Tahtalı Dam, and Karaidemir Dam were examined. After the identification of species, the contents of digestive tracts of every fish sample were filtered with membrane filter and were processed with 30 ml %35 hydrogen peroxide (H2O2) solution. Filtered samples were recorded according to the type and color of microplastic detected by stereo microscope. Polymer verification of selected microplastic samples was done by Fourier transform infrared spectrometry (FTIR). FTIR results matched with chlorinated polyethylene, polystyrene, and neoprene. A total of 610 MP particles were extracted from the gastrointestinal systems of all fish species (n=406). The ingested MPs were only fibers with the dominant plastic color was being blue. The length of microplastics ranged from 0.10 to 4.85 mm. Mean MP length size in C. carpio species 1.40±0.90 mm, in C. gibelio species 1.32±0.88 mm, in Alburnus spp. 1.23±0.90 mm, in S. erythrophthalmus species 0.94±0.79 mm, in V. vimba species 1.11±0.69 mm, in P. fluviatilis species 1.34±0.89 mm, in N. fluviatilis species 1.25±0.97 mm. Among the studied species, the most fiber microplastic was found in Perca fluviatilis. According to habitat and feeding features the highest number of microplastics was found in benthopelagic and invertivore fish. These results will be the principal data for future studies of microplastics in inland waters. The data of this thesis is anticipated to form the basis for new research and decision-making processes.