Plastic in Urban Streams: Distribution, Transport, and Influence on Biofilm Community Composition

• Main Author: Vincent, Anna Elizabeth Sleeter
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2019
• Subjects: Biology; Ecology
• ISBN: 9781658420181; 1658420187

Accelerated production and disposal of plastic is generating global accumulations of plastic litter in natural ecosystems. The capacity for plastic to undergo physical, chemical, and biological processes within freshwaters is understudied, and remains a critical component of global plastic budgets and future management interventions. Our objectives were to: (1) quantify the abundance of microplastic within different river habitats, (2) adapt organic matter ‘spiraling’ metrics to measure microplastic transport concurrent with fine particulate organic matter (FPOM), and (3) measure the influence of plastic polymer type on biofilm community composition and function in urban streams spanning a geographic gradient. We quantified microplastic and FPOM abundance by habitat (surface water, water column, benthos), and calculated downstream particle velocity, index of retention, turnover rate, and spiraling length for both particle types. Downstream particle velocity and indices of retention were similar. However, microplastic showed lower turnover rates and longer spiraling lengths relative to FPOM, attributed to the slow rates of plastic degradation. Overall, results suggest that the same microplastic particles can be retained, transported long distances, and released into larger bodies of water. In our biofilm analysis, we documented robust microbial growth on natural and synthetic substrata. Biofilm activity was somewhat affected by plastic surfaces, including enhanced biomass and reduced taxonomic (OTU) richness. Community composition was driven most strongly the by environmental conditions at each site, and not by the chemical composition of the plastic growth substrate. These projects provide insight on the pervasive nature of plastic pollution and contribute to global plastic budgets.