Preferred Name
Jordan Cynthia Heydt
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
ORCID
https://orcid.org/0009-0006-8849-0148
Date of Graduation
5-15-2025
Semester of Graduation
Spring
Degree Name
Master of Science (MS)
Department
Department of Biology
First Advisor
Kristin Yoshimura
Second Advisor
Morgan Steffen
Third Advisor
Steven Cresawn
Abstract
Rock pools are ephemeral aquatic environments that offer a unique opportunity to study complex communities and their responses to environmental changes. The urban James River rock pool system consists of over 700 individual rock pools varying in size and depth. This unique urban freshwater ecosystem has been studied for its invertebrate, plant, and zooplankton populations but not for its microbial community composition. To fill that gap, the microbial community of this system was characterized using 16S rRNA gene sequencing, and the influence of environmental variables on the community composition was analyzed. Our findings show variation in microbial community composition across pools in relation to flood height, shade cover, temperature, and nutrient concentrations, while pool depth and chlorophyll a concentrations had a lesser impact on microbial composition. At the phylum level pools were mostly dominated by Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria, however at the amplicon sequence variant (ASV) level there was significant variability, with 14,063 ASVs observed in a single pool. The strongest environmental drivers of microbial community composition were flood height, temperature, shade, and urea concentration. Ammonia concentrations affected the differential abundances of the highest number of microbial classes, followed by temperature and depth, while no microbial classes were differentially abundant in response to chlorophyll a or nitrite concentration. A surprising finding was the presence of human gut microbes within this freshwater ecosystem, possibly indicating wastewater contamination. This study provides a baseline for long-term studies investigating how the microbial community in the James River rock pool ecosystem changes over time and in response to changes in environmental conditions.
Included in
Biodiversity Commons, Bioinformatics Commons, Environmental Health Commons, Environmental Microbiology and Microbial Ecology Commons, Terrestrial and Aquatic Ecology Commons
