Historic fish samples from the Southeast USA lack microplastics

Abstract Most of earth’s systems and the organisms that inhabit them are known to contain microplastics, which are well documented to have lethal and sublethal effects on living things. Due to their generally short timeframe and recent focus, contemporary studies of microplastics in fish are unable to inform past patterns of microplastic ingestion, and as such there is a knowledge gap regarding when microplastics began showing up in fishes. We examined n = 185 historical (museum) fish samples representing seven species from five freshwater systems across 51 years in order to look for microplastic samples over time. We found only three microplastic particles, two of which were in the more recent years of collection (1996 and 2006). Although our results are not conclusive toward understanding the true nature of microplastic occurrence over time in fishes, our findings present strong evidence that southeast U.S. stream fish likely did not ingest large numbers of microplastics during the 20th century.