Date of Award
1-1-2024
Document Type
Dissertation
Degree Name
Ph.D. in Biological Science
First Advisor
Colin R. Jackson
Second Advisor
Brice Noonan
Third Advisor
Peter Zee
School
University of Mississippi
Relational Format
dissertation/thesis
Abstract
Spatial variation in bacterial communities, or bacterial biogeography, is important for understanding the role of microorganisms in biogeochemical cycles. In the Southeastern United States, aquatic ecosystems are highly biodiverse and imperiled, yet few studies have investigated bacterial biodiversity and biogeography in this region. In this dissertation, I aimed to understand the bacterial biogeography in aquatic ecosystems in the Southeastern United States and how this spatial variation relates to abiotic factors in these ecosystems. To do this, I analyzed biogeographic patterns in bacterial communities from three distinct types of aquatic ecosystems (rivers, a lake, and beaches) and conducted a microcosm experiment investigating the influence of aquatic plants on their surrounding aquatic bacterial communities. For riverine bacterial biogeography, analysis of partial 16S rRNA gene sequences from water and sediment at 22 sites on seven rivers in two river basins showed that bacterial communities in water and sediment differed between river basins and rivers at broad (phyla) and fine taxonomic levels. To investigate finer scale aquatic bacterial biogeography, bacterial communities were characterized from 88 surface water samples taken from a single lake. These bacterial communities showed fine-scale spatial heterogeneity related to environmental conditions across the lake. To determine spatial variation in bacterial communities of beaches, partial 16S rRNA genes were sequenced from samples of sand and seawater collected from 50 beach sites spanning the entire Mississippi coastline. Communities in sand and seawater showed different spatial patterns along the coast, but physicochemical variables explained little of this spatial variation. To test whether aquatic plants affect the composition and activity of bacterial communities in the surrounding water, I conducted a microcosm experiment using three plant species. Plant identity and plant richness were important in determining the effects on surrounding aquatic bacterial communities, but shifts in bacterial community composition did not relate to changes in microbial function. These studies showed high spatial heterogeneity of bacterial communities in aquatic ecosystems of the Southeastern United States and that aquatic bacterial biogeography was influenced by both abiotic and biotic factors.
Recommended Citation
Heiman, Jordan, "Spatial Variation of Microbial Communities in Aquatic Ecosystems in the Southeastern United States" (2024). Electronic Theses and Dissertations. 3016.
https://egrove.olemiss.edu/etd/3016
