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Microplastic Pollution in Headwater Streams and a Small Freshwater Fish

Microplastics 2026
Elizabeth S. Gordon, Maeve H. Ahern, Nicole E. Burdick, Kaitlyn E. Prentiss, Paulina Torres, Daniel Welsh

Summary

Scientists found tiny plastic pieces (microplastics) in every single small stream they tested in Massachusetts, and nearly every fish they examined had plastic in its gut—some with over 200 pieces. This matters because these small streams and fish are often overlooked in pollution research, yet they're part of the food chain that can eventually affect the water and fish humans eat, suggesting microplastic contamination may be far more widespread in nature than previously realized.

Body Systems
Study Type Environmental

Microplastic pollution is an increasingly important environmental concern, especially in aquatic ecosystems. However, research on microplastics has historically been skewed towards marine systems and large freshwater systems, leading to an incomplete picture of the potential prevalence and scope of this type of pollution. In order to understand the potentially ubiquitous nature of freshwater microplastics, our study focused on 11 small headwater streams in north–central Massachusetts (USA) and a small freshwater fish species, the Blacknose dace (Rhinichthys atratulus). Microplastics were found in all sampled streams. Considerable variation in the number of stream microplastics existed, with concentrations ranging from 0.3 to 45.1 pieces per cubic meter of water. Microplastics were assessed in 14–20 fish from each of five of these streams. The vast majority of all fish had microplastics, with some individuals having over 200 pieces in their digestive tract. The number of fish microplastics was not found to be statistically related to the amount of water microplastics, the length of the fish, or the land use surrounding the streams. Together, these results illustrate that microplastics are prevalent and that small freshwater ecosystems need to be considered when assessing the full impact this source of pollution may have on ecosystems.

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