Date of Award

9-6-2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Timothy Hoellein

Abstract

Anthropogenic microparticles (MP) (i.e., particles < 5 mm) are defined as materials of manufactured origin found in the environment. They are widespread and a rapidly emerging global contaminant. MP include microplastics (< 5 mm), as well as other microfibers or particles, which can be synthetic, semi-synthetic and non-synthetic. Rivers are a critical source of plastics to oceans, and MP within rivers are retained in part though biological processes, including ingestion. MP ingestion by freshwater biota varies by proximity to point sources (e.g., wastewater treatment plants; WWTP), overall environmental concentrations, and trophic level and functional feeding groups, but few studies have examined these factors together. In our first study we examined fish collected in the North Shore Channel of the Chicago River to determine MP abundance within organisms. We then compared trophic position (i.e., δ15N) and proximity to a WWTP. With all species combined, MP concentration were not significantly different across study sites, but stable isotopes increased downstream. Considered individually, MP abundance relative to WWTP proximity varied by species, which we attributed to habitat preference and mobility. In a second project, we collected macroinvertebrates from three different watersheds in North America and compared the abundance of MP in macroinvertebrates to concentration within the environment (i.e., water column, surface, and benthic). Functional feeding groups were a significant predictor in the amount of microparticles found in macroinvertebrates. Additionally, the concentration of water column microparticles showed a positive relationship with all macroinvertebrate’s microparticle abundance. Results will aid in understanding the ecological impacts of MPs on aquatic food webs and the pathways in which they can enter.

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