Conowall, Peter2023-11-282023-11-282022https://hdl.handle.net/11299/258565University of Minnesota M.S. thesis. 2022. Major: Water Resources Science. Advisors: Kathryn Schreiner, Elizabeth Austin-Minor. 1 computer file (PDF); vi, 78 pages.Microplastic (plastic particles < 5mm) pollution has potentially detrimental impacts on aquatic and marine ecosystems. Here we examine the extent of microplastic pollution in four small inland lakes in Minnesota, USA (Elk, Peltier, Ten Mile, and White Iron Lakes), which represent a range of human impacts, as well as a variety of watershed and lake characteristics. Surface water particulates, benthic sediments, and filter and visual feeding fish were collected in the summers of 2019 and 2020 to examine the loading of microplastics into these lakes and their distribution within these ecosystems. Results show that catchment area and urban development were the most influential factors on microplastic loading. Surface water microplastic concentrations ranged from 16,000 microplastics km-2 in Elk Lake to 150,000 microplastics km-2 in White Iron Lake, comparable to concentrations from very remote lakes (Lake Hovsgol, Mongolia, 20,264 microplastics km-2) to more anthropogenically influenced lakes (Lake Erie, USA, 105,500 microplastics km-2) (Eriksen et al., 2013; Free et al., 2014). The concentrations in benthic sediments ranged from 14 microplastics kg-1sed in Elk Lake to 190 microplastics kg-1sed in Peltier Lake and were not directly correlated to surface water concentrations. Consumption by filter feeding fish was determined to be dependent on surface water concentrations, while consumption by visual feeding fish was not. These results indicate that differences across small aquatic ecosystems will require dynamic management of microplastic pollution.enEcologyFisheriesLimnologyMicroplasticsThesis or Dissertation