ABSTRACT: Microplastics have emerged as a major contaminant of concern in a host of ecosystems, including freshwater systems. Previous work has documented the abundance of microplastics in the bodies of various organisms, finding that aspects of an animal’s niche (feeding habits, habitat choice, etc.) may influence exposure to microplastic contamination. To further our understanding of microplastic abundance in freshwater systems, we conducted a survey of freshwater fish taken from the lower Kaskaskia River in Southern Illinois, USA. The first sampling site (done via direct current boat electrofishing) was stationed directly below the Carlyle Lake dam (a heavily used recreational site with abundant pollution from litter) with two additional downstream sites also sampled. Five species of fish (flathead catfish Pylodictis olivaris, freshwater drum Aplodinotus grunniens, smallmouth buffalo Ictiobus bubalus, white crappie Pomoxis annularis, and gizzard shad Dorosoma cepedianum) of differing feeding ecologies were sampled, dissected, and subsequently examined for microplastics both visually (examinations of gills and stomach contents under microscope) and chemically (analysis of nanoplastic concentration in muscle tissue). Results revealed differences in microplastic load between fish species and between sites, as well as differences in measures of contamination using visual and chemical methods. Our results add to the present knowledge of microplastic abundance in organisms, and specifically how feeding type and proximity to sources of human pollution may impact microplastic abundance in freshwater fish.
