Date of Submission
5-2024
Document Type
Thesis
Degree Name
Master of Science in Environmental Science
Department
Biology and Environmental Sciences
Advisor
Nikolas Stasulli, Ph.D.
Committee Member
Sharon Kahara, Ph.D.
Committee Member
Jean-Paul Simjouw, Ph.D.
Keywords
Biofilm, Polypropylene Microplastic, Natural Stone, Quinnipiac River Watershed, Unimpaired and Impaired Waterbodies
LCSH
Biofilms, Polypropylene, Stone, Quinnipiac River Watershed (Conn.)
Abstract
Biofilms comprise a unique community of microorganisms, including bacteria, algae, and fungi that form a matrix of extracellular polymeric substances (EPS) to create an absorptive surface on which chemical interactions can occur. Accumulation begins immediately upon introduction into an environment; in the case of microplastics, the EPS matrix colonizes into a distinct biome that alters the topography and density of the microparticle as it ages. Environmental nutrient levels, seasonality, and geography influence biofilm formation. This project compared the microbial diversity of biofilms on microplastic versus stone substrates cultured in an impaired and unimpaired section of the Quinnipiac River Watershed over a 90-day study period. We evaluated fecal coliform colony accumulation in the microplastic substrate over that of stone in conjunction with site location A Mann-Whitney U test revealed significantly greater total colony counts in the impaired Quinnipiac River compared to unimpaired Honeypot Brook (W=583, p=0.037). There were also greater total colonies in microplastics compared to stone substrate (W=1038, p=0.022). Generalized Linear Modeling indicates that both location and substrate explained the presence of total coliforms. A higher median count was seen at the impaired site on the microplastic surface. Comparison of sites using Simpson’s Diversity Index showed a slight difference in alpha diversity on microplastics, particularly at the unimpaired location. Bray-Curtis and Jaccard dissimilarity plotting indicated differences in biofilm community were detected between sites, but no differences were seen between substrates. Community analysis indicated that river rock and microplastics differed by two Families out of the top ten assessed. Of note was the presence of Aeromonadaceae, a known aquatic pathogen, retained on the microplastic surface and not on the stone. Our results support the hypothesis that impaired waterbodies with a microplastic burden can potentially retain a greater proportion of total coliforms with a unique biofilm community compared to that of an unimpaired site. Future directions include filtration of common fecal coliform operational taxonomic units to determine abundance for site and substrate location. Comparison of this study with that of environmental community analysis would provide valuable insight into microplastic preferential surface attachment.
Recommended Citation
Gilewski, Anne L. LVT, "Comparison of Biofilm Community Diversity and Accumulation on Polypropylene Microplastic Versus Natural Stone in an Unimpaired and Impaired Section of the Quinnipiac River Watershed" (2024). Master's Theses. 224.
https://digitalcommons.newhaven.edu/masterstheses/224