Amanda R. McCormick Thesis Defense: Project Description
Title: Anthropogenic litter and microplastic in urban streams: abundance, source, and fate
The accumulation and ecological effects of anthropogenic litter (AL; trash) and microplastic (particles <5mm) are well-documented in marine ecosystems. Rivers transport organic matter, nutrients, and pollution between terrestrial and marine ecosystems, but their role in transporting AL and microplastic is unknown. AL enters rivers from recreation, industry, runoff, and illegal dumping. Microplastic fibers (i.e., synthetic fabrics) and pellets (i.e., abrasives in personal care products) are abundant in wastewater treatment plant (WWTP) effluent which enters rivers. AL and microplastic have notable ecological implications in marine systems, but their impact on riverine biota is largely unknown. The objectives of this thesis were to: (1) quantify the abundance and composition of AL in urban streams, (2) measure AL flux in rivers by calculating input and output rates, and (3) measure the concentration and analyze bacterial community composition of microplastic in rivers.
In summer 2014, we collected AL from 5 urban streams in the Chicago metropolitan area, which span a gradient of urban land use. We found higher AL density in riparian habitats and higher AL mass in stream benthos. Overall, reach-scale metrics (i.e., parking spaces and human activities) explained variation in AL abundance and composition, rather than watershed-scale characteristics (i.e., urban land use). In our flux studies, we monitored the movement of AL in seasonal and biweekly studies and demonstrated that AL is a mobile substrate in rivers whose movement is mediated by material type and hydrology. Finally, we collected surface water samples upstream and downstream of 9 WWTPs in Illinois, USA and found higher microplastic concentrations downstream at all but two streams. Using next generation sequencing of the 16S rRNA genes, we demonstrated that microplastic offers a unique habitat for microbial colonization, and it selects for bacteria associated with plastic degradation, biofilm formation, and pathogens.
This research was funded by the Illinois Water Resource Center and the Graduate School of Loyola University Chicago. Thank you to my thesis advisor Dr. Timothy Hoellein and committee members Dr. Martin Berg and Dr. John Kelly for their comments on this thesis. Thanks also to Maxwell London, Miguel Rojas, Joshua Hittie, Melaney Dunne, Margaret Sladek, Maxwell Jabay, Joseph Schluep, and the Hoellein Lab at Loyola University Chicago for their assistance in the field and laboratory. Thank you to Roy Kressman, Mike Wisniewski, Bill Perry, Jake Callahan, Jim Gorman, Carl Christensen, and Kyle Sinclair for their assistance in sample collection. Finally, thank you to my family and friends for encouraging me throughout the thesis writing process.
Amanda McCormick was born and raised in northwest Indiana. She attended the University of Michigan in Ann Arbor, MI and earned a Bachelor of Science degree in Ecology and Evolutionary Biology and a Secondary Teaching Certificate in Mathematics and Biology. She also studied abroad at James Cook University in Cairns, Australia where she took courses in marine biology, environmental science, and biodiversity. After graduating, she was a Teach for America Corps member at West Gary Lighthouse Charter School in Gary, Indiana where she taught middle school mathematics. At Loyola, Amanda was a teaching assistant for introductory environmental science and ecology courses and participated as a Masters Mentor with Achieving College Excellence (ACE).
Dr. Timothy Hoellein
Dr. Martin Berg
Dr. John Kelly