Tracing microplastic pathways: assessing pollution in a freshwater lake with high tourist activity

Abstract Lake Gölcük represents a significant natural freshwater resource within the Gediz River basin, located in the Ödemiş district of İzmir, Türkiye. The ecosystem has experienced considerable anthropogenic pressure from expanding settlements and tourism activities. This study aimed to assess the spatial distribution and severity of microplastic (MP) contamination in the lake. Microplastics (MPs) were quantified and characterized in water, sediment, fish muscle, gastrointestinal tract, and macroinvertebrate tissues collected from three spatially distinct stations using integrated morphological and spectroscopic methods. Macroinvertebrate samples were processed for MP contamination following standardized field sampling and laboratory protocols. The results show that Station 2, corresponding to the primary recreational zone, exhibited the highest MPs concentrations in water (81.33 ± 4.16 particles L⁻ 1 ) and sediment (30.00 ± 4.16 particles kg⁻ 1 ). In macroinvertebrates, MP loads ranged from 0.01 to 0.09 particles mg⁻ 1 , with peak values observed in Haliplidae and Veliidae taxa. European perch (Perca fluviatilis) contained 7.00 ± 2.00 particles g⁻ 1 in muscle tissue and 1.67 ± 0.58 particles g⁻ 1 in the gastrointestinal tract, whereas gibel carp ( Carassius gibelio ) from Station 1 showed no detectable MPs. Fibers dominated the morphotype distribution, with blue, black, and transparent particles most prevalent. Polyethylene, polypropylene, polyethylene terephthalate, and nylon constituted the predominant polymer compositions. Collectively, these findings confirm substantial MP contamination across both abiotic (water, sediment) and biotic (fish, macroinvertebrates) compartments of Lake Gölcük, posing potential ecological risks to resident biota and overall ecosystem integrity. The results contribute critical baseline data on MP distribution in Turkish inland waters and underscore the urgent need for protective measures amid escalating tourism pressure.