Honors College Theses

Publication Date



Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Risa A Cohen


Plastics enter the environment from many sources, including clothing made from synthetic textiles, which shed a form of microplastics (microfibers) during their production, use and disposal. The impacts of microfibers on freshwater organisms are relatively unknown, therefore we tested the hypothesis that short- and long-term effects of microfibers on the aquatic worm, Lumbriculus variegatus, depend on the type of synthetic microfiber present. Microcosms containing L. variegatus, sediment and water were exposed to either no fibers (control) or one of three microfiber treatments (nylon, polyester or olefin) at the same concentration for 48 hours or 28 days. At the end of each exposure, L. variegatus were counted, weighed, and the number of microfibers ingested were determined. The number of microfibers recovered varied across treatments; polyester occurred at a higher concentration than nylon and olefin in both time periods. After 48 hours, polyester microfibers were approximately 50 times more prevalent than nylon and olefin fibers. The amount of olefin recovered increased the most over time, nearly 4.5 times from 48 hours to 28 days. Minimal mortality occurred after 48 hours, and the population of L. variegatus doubled in size after 28 days across all treatments. Given that L. variegatus microfiber ingestion appeared to be affected by the type of microfiber, and L. variegatus are consumed by larger organisms such as fish, these data could help determine which microfibers are likely to enter the food web and support additional water quality policies to reduce the release of textile waste into freshwater systems.

Thesis Summary

Microfibers, the most common microplastics in the environment, are deposited in sediment where they interact with freshwater organisms such as the worm, Lumbriculus variegatus. The type of microfiber and duration of exposure affected the number of fibers ingested by L. variegatus, but no differences in growth, reproduction, and mortality occurred.