First assessment of microplastic consumption in sympatric black bass species in a temperate river system

Microplastics (i.e. plastic particles ranging in size from 1 μm to 5 mm) are an understudied emerging pollutant in rural rivers that may pose significant health risks to organisms, and their monitoring is resource-intensive and costly. This study quantifies microplastic consumption in the Monongahela River, West Virginia, USA in three sympatric black bass species: largemouth bass (Micropterus nigricans), smallmouth bass (Micropterus dolomieu) and spotted bass (Micropterus punctulatus). Utilizing an existing sampling program and low-cost methodology, the spatial variability of microplastic ingestion between navigational pools within the Monongahela River and limited temporal variability within a pool was examined to determine differences between the sympatric species in total and shape-size fractions. Microplastics were found in all fish surveyed and Bayesian regression models revealed that microplastic consumption is influenced by species, spatial location and temporal factors, with significant interspecies and intraspecies differences in microplastic consumption. The results emphasize the variability that exists even among similar species and reinforce the need to monitor microplastic pollution in rural river systems to evaluate the ecological risks of microplastic pollution.