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Thesis
Seasonal Variation of Epiphyte Abundance and Nitrogen Fixation Rates of Two Seagrass Species in the Pensacola Bay System
University of West Florida Libraries
Master of Science (MS), University of West Florida
2023
Abstract
Nitrogen fixers can enhance nitrogen availability for seagrass communities that are often nitrogen limited. However, the role of epiphytic nitrogen fixers in seagrass communities with anthropogenic nutrient inputs is not well understood. This is the first study in the Pensacola Bay System (PBS) to identify seasonal variation in nitrogen fixation, nifH gene abundance, and epiphyte biomass on leaves of two seagrass species, Thalassia testudinum and Halodule wrightii, and whether level of suburban development affected the activity, abundances, and biomass of epiphytic diazotrophs. Nitrogen fixation rates on seagrass leaves were determined and the nifH gene from three diazotrophic subgroups was amplified from extracted epiphyte DNA as a measure of diazotroph abundance. Developed and conserved sites had similar epiphyte biomass, nitrogen fixation rates, and relative abundances of the nifH gene for both seagrass species. These similarities were likely caused by similarities in nutrient concentrations and overall environmental conditions between sites. While the lowest average fixation rates were measured in summer during peak seagrass growth and the highest average fixation rates were recorded in fall during seagrass senescence, these differences were not significant. Group B cyanobacteria accounted for the largest portion of the total relative nifH abundance of measured nifH subgroups. Heterocystous cyanobacterial symbionts (Richelia spp. and Calothrix spp.) were only predominant at a few sites. This study is the second report of seagrass epiphytes containing nifH phylotypes related to diatom symbionts. Further studies are needed to better understand the relationship between epiphytic diazotrophs and seagrasses in the PBS and other coastal ecosystems.
Details
- Title
- Seasonal Variation of Epiphyte Abundance and Nitrogen Fixation Rates of Two Seagrass Species in the Pensacola Bay System
- Resource Type
- Thesis
- Contributors
- Jane Caffrey (Committee Chair)Lisa Waidner (Committee Member)Amber Hardison (Committee Member)Philip Darby (Committee Member)
- Publisher
- University of West Florida Libraries
- Format
- pdf
- Number of pages
- 96
- Copyright
- © 2023 Lacey Taylor Bowman
- Identifiers
- 99380482493106600
- Academic Unit
- Biology
- Language
- English
- Awarding Institution
- University of West Florida; Master of Science (MS)
- Theses and Dissertations
- Master of Science (MS), University of West Florida