Microplastic footprints in marsh frogs (Pelophylax ridibundus) from two Turkish lakes

Abstract

Microplastic (MP) pollution poses a growing threat to freshwater ecosystems with potential consequences for inhabiting species such as amphibians. In this study, MP contamination in biotic (Pelophylax ridibundus—gastrointestinal tracts) and abiotic (water, sediment) samples from two sampling sites (Büyükçekmece Lake—high human activity, Şavşat Karagöl Lake- low human activity) was investigated between June and August 2024. Water and sediment samples were collected from 10 stations with 15 adult frogs from each site. MPs were detected in 16.6% of frog gastrointestinal tracts (GITs), with fibers dominating (80%) over fragments (20%), and an average of 0.2 MP−1 in Büyükçekmece population and 0.13 MP−1 in Şavşat Karagöl population. In the environment, MPs occur in 20% of water samples and 30% of sediment samples, with polymer types including polyethylene terephthalate (PET, 29%), polyethylene (PE, 29%), ethylene vinyl acetate (EVA, 21%), polypropylene (PP, 14%), and polytetrafluoroethylene (PTFE, 7%). Büyükçekmece Lake showed higher sediment MP prevalence (40%) than water (10%), while Şavşat Karagöl had more MPs in water (30%) than in sediment (20%), reflecting site-specific dynamics. No significant differences were found between water and sediment MP concentrations. These findings highlight MP occurrence into both the biotic and abiotic components of these ecosystems, with implications for amphibian health and freshwater quality, particularly in areas affected by human activity.