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CC BY-NC-ND V4.0, Open Access
Thesis
Does Nitrogen, Phosphorus, and/or Silica Limit Phytoplankton Growth and Community Composition in the lower Columbia River?
Washington State University
Master of Science (MS), Washington State University
12/2024
DOI:
https://doi.org/10.7273/000007258
Abstract
Phytoplankton communities play an essential role in aquatic ecosystems, contributing to primary production and influencing food webs. The goal of this research was to investigate whether major nutrients (nitrate, phosphate, and silicate) limit phytoplankton community and growth in the lower Columbia River (CR). From May – September 2021, we conducted a series of 5-day incubation experiments using surface water samples collected from the Washougal dock in Washougal, WA, USA, with nitrate, phosphate, and silicate added in separate treatments. Our results showed consistent seasonal variations in ambient surface temperature, nutrient concentrations, and chlorophyll a levels in the lower CR. In our incubation experiments, we found significant increases in chlorophyll a concentrations with the addition of silicate during June and July, with a significant effect on the diatom assemblage on Day 5 in June, suggesting silicate limitation of diatoms during late spring in the lower CR. We observed a significant shift in the relative biomass proportion of diatom genera during June in response to the addition of silicate. Specifically, the diatom community transitioned from a mixed assemblage dominated by
Stephanodiscus. This increase in Stephanodiscus biomass could have broader implications for the diatom community in the lower Columbia River. When silicate is not limiting, the dominance of Stephanodiscus may result in a more nutritious phytoplankton community for higher trophic levels, as this genus is particularly carbon-rich. Our study contributes to the expanding understanding of how nitrate, phosphate, and silicate influences phytoplankton growth and community composition in the Columbia River, with important implications for food web dynamics.
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Details
- Title
- Does Nitrogen, Phosphorus, and/or Silica Limit Phytoplankton Growth and Community Composition in the lower Columbia River?
- Creators
- Bianca B. Wong Rodriguez
- Contributors
- Gretchen Rollwagen-Bollens (Chair)Stephen M. Bollens (Committee Member) - Washington State University, School of the Environment (CAS)Sarah S. Roley (Committee Member) - Washington State University, School of the Environment (CAS)John Harrison (Committee Member) - Washington State University, School of the Environment (CAS)
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 46
- Identifiers
- 99901195638001842
- Language
- English
- Resource Type
- Thesis