Date of Award

2021

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Anthropogenic litter (i.e., trash; AL) is increasing in aquatic ecosystems worldwide. AL shows a patchy, uneven distribution in lotic ecosystems due to heterogeneity in its sources, how it moves, and mechanisms of retention. In addition, the diversity of material types, size, and mobility makes developing techniques to measure AL assemblage in rivers a challenge. In rivers, watershed land-use and riparian features likely impact AL abundance and composition, but this impact is not fully understood. Measuring AL can be time consuming and labor intensive, so rapid assessments are needed for ecosystem managers to quantify the level of AL impairment in a stream. The objectives of the research in this thesis were to 1) quantify the relationship between AL abundance, mass, and composition in streams to different watershed land use and a range of riparian features and 2) determine the efficacy of two rapid AL measurement methods: a qualitative assessment and a visual tally. We measured AL in 30-m reaches of 9 streams across northeast Illinois which span a gradient of land use and biological quality using the 2 rapid methods and manual collection. Results showed AL abundance (as No./m2) and the proportion of AL produced from single-use items (i.e., plastic and glass) were positively related to urban watershed land use, population density, and impervious surface cover and negatively related to agricultural land use. Local features that increase access to the river (e.g., proximity to roads and urbanized riparian zones) were associated with higher AL. The visual tally was predictive of AL density across sites as revealed through manual collection but underestimated total AL, particularly for ‘cryptic’ categories (i.e., easily overlooked or layered materials). Accurately quantifying AL abundance, composition, and relationships with watershed and stream features is essential to identifying the sources, transport, and fate of AL as well as supporting successful management of AL in streams.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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