Presence of Microplastics in Ephemeroptera, Plecoptera, and Trichoptera of North Cascades National Park

The presence of microplastics in glaciers has led to concern for freshwater systems connected to the glaciers. In areas such as the North Cascades (WA), glacier runoff could transport these microplastics into the watershed and into organisms in the streams. Benthic macroinvertebrates are good indicators of water quality because they may be sensitive to pollution. Their relatively low status on the freshwater food chain suggests the possibility for accumulated microplastics in macroinvertebrates to be a source of microplastics to predators, proving a hazard to the health of freshwater ecosystems. Samples analyzed in this study were Emphemeroptera, Plecoptera, and Tricoptera collected from several streams and lakes in the North Cascades National Park. Samples were collected in 2018 and preserved in ethanol. Samples were composited based on Order and site. Whole organisms were digested in 10% potassium hydroxide and filtered through a 1.2 µm borosilicate filter. Microplastics were identified under a microscope at 40X magnification and characterized by type and color. Plastic types included fibers, fragments, films, foams, and pellets. Presently, microplastics have been recovered from 100% of the 15 samples analyzed. A total of 138 microplastics were recovered. Fibers constitute the majority of recovered microplastics (99.1%). The three most common fibers are blue, black, and transparent. Blue fibers account for 47.6% of fibers, black 22.9%, and transparent 27.6%. One fragment was recovered, and no films, foams, or pellets were observed.