Determination of the presence of biomicroplastics in common carp (Cyprinus carpio) in Almus dam lake

This study aimed to investigate the gastrointestinal systems of carp (Cyprinus carpio) in Almus Dam Lake for microplastic ingestion. For this purpose, 30 carp specimens were purchased from local fishermen in Almus in July 2025. Morphometric measurements of the fish were taken, and their gastrointestinal systems were analyzed to determine abundance (number of microplastics per individual) and characterization (shape, color, and size) of microplastics. The percentage of fish contaminated with microplastics was 100%. The average number of microplastics per individual was calculated to be 12.66±7.55 MP/individual. Microplastic identification was performed using a stereo microscope for visual inspection. It was determined that the vast majority of microplastics were in fibrous form (72.11%), and the highest proportion in the color distribution was black, blue, and red microplastics. According to size distribution classification, the majority were smaller than 5 mm and were classified as microplastics. Furthermore, a statistically significant positive correlation was found between total length and the number of microplastics (Spearman's ρ = 0.42, p < 0.05). The study confirms the presence of microplastic pollution in the Almus dam reservoir and shows that carp are exposed to this pollution. This study contributes to the literature as it is one of the first microplastic studies conducted on fish in the Almus Dam Lake ecosystem. It is recommended that more effective solid waste management and monitoring mechanisms be implemented to reduce microplastic input into the Almus Dam Lake basin, particularly from fishing waste and human-induced pollution. Furthermore, regular biological monitoring programs based on standardized protocols should be implemented to track temporal changes in microplastic pollution in aquatic organisms.