Occurrence of microplastics in fishing cat (Prionailurus viverrinus) scat: Hidden threats to wetland ecosystems of Thailand

Abstract

Wetland ecosystems in Southeast Asia face threats from habitat degradation and plastic pollution, with microplastics posing emerging risks to biodiversity and apex predators like the Vulnerable fishing cat (Prionailurus viverrinus). This study investigated microplastic occurrence in fishing cat scat from the Khao Sam Roi Yot (KSRY) wetland in Thailand, a key habitat supporting an estimated 127 individuals, to assess contamination prevalence, characteristics, and sources. From August 2022 to July 2023, 192 scat samples were collected across aquaculture, agricultural, and coastal plain habitats and processed using hydrogen peroxide digestion, followed by stereomicroscopic examination for visual identification and Fourier-transform infrared (FTIR) spectroscopy examination for polymer identification. Anthropogenic particles were detected in 28 scat samples (14.6%), with confirmed plastics in 26 scat samples (13.5%), yielding 251 plastic particles primarily as fragments (86.1%), blue in color (75.3%), and polypropylene (PP) (87.6%). Contamination was highest in aquaculture areas (67.9% of positive scat samples), corroborated by environmental surveys identifying plastic debris from nets, sacks, and bottles. These findings provide the first evidence of microplastic ingestion in fishing cats in Thailand possibly via trophic transfer from contaminated prey, highlighting potential health risks including gastrointestinal damage and chemical exposure. Urgent mitigation through waste management in aquaculture and policy interventions is essential to safeguard wetland ecosystems and endangered species conservation.