Contamination of microplastics in Brantas River, East Java, Indonesia and its distribution in gills and digestive tracts of fish Gambusia affinis

The Brantas River is currently vulnerable to microplastics pollution. Microplastics not only pollute the aquatic environment but also enter the body of fish and other aquatic organisms. This research is aimed at deciding if microplastics were present in the waters and the gills and digestive tract of the Gambusia affinis fish of the river. It also looked at differences in the abundance of several types of microplastics found in the various organ samples and locations. Field research was conducted from January 2020 to March 2020. The microplastics were identified by type, size, color, and the abundance of each type was calculated. The types of microplastics identified were fragments, fibres, films, and pellets. Microplastics of 0.1 mm size are predominant and formed about 76%–100% of the microplastics that were found. Black microplastics were more common in water samples (24%), gills (43%), and digestive tract (46%). The greatest abundance of microplastic fragments was found in water samples of 4066.67 particles/m³, 1352.78 particles/gram in gill samples, and 2138.89 particles/gram in the digestive tract. Multivariate tests for variants of microplastic types found in the organs at different sampling locations gave a p-value <0.05. These results indicate a difference in the abundance values of microplastic species in different organ samples and sites.