ASSESSMENT ON MICROPLASTICS CONTAMINATION IN FRESHWATER FISH: A CASE STUDY OF THE UBOLRATANA RESERVOIR, THAILAND

Abstract

Microplastic pollution is now a global issue. Reservoirs are an enclosed aquatic environment at
risk from accumulation of microplastics. Few studies have used fish species as bio-indicators to monitor
microplastic contamination in reservoirs. Freshwater fish were caught by local fishermen from 10 stations
around the Ubolratana Reservoir, Thailand in October 2018 and the abundance, size, color and shape of
microplastic particles in their stomachs and intestines were investigated. Fourteen fish species were examined.
Results showed that 96.4% of the fish had ingested microplastics at mean abundance of 2.921.30 particles per
fish, with significant differences of abundance between species. Microplastic abundance was highest in
carnivorous fish Parambassis siamensis (4.111.08 particles per fish). The most common size of ingested
microplastics was over 0.5 mm (66.4%), with 51.0% as blue color and 98.2% fiber shaped. High levels of
microplastics were ingested by fish located in the middle and lower parts of the reservoir. Results revealed that
blue fiber microplastics dominantly observed in fish were derived from the breakdown of nets used for fishing
activities.