Dissertation
CYANOBACTERIAL BLOOM DYNAMICS IN THE COLUMBIA RIVER BASIN: EFFECTS OF BIOTIC AND ABIOTIC FACTORS
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/117153
Abstract
Together, eukaryotic algae and prokaryotic cyanobacteria comprise a taxonomically broad group known as phytoplankton that are vital energy producers in aquatic food webs. Cyanobacteria and some algae have the potential to form harmful blooms due to high biomass or production of toxins. Phytoplankton bloom magnitude, timing, and species composition are difficult to predict across freshwater systems because such dynamics are influenced by interacting abiotic and biotic factors, and are further altered by anthropogenic stressors such as climate change and eutrophication. The intent of this research was to explore phytoplankton, and specifically cyanobacterial, bloom dynamics across freshwater systems of the Columbia River (CR) basin, with a focus on growth and assemblage changes in response to biotic and abiotic factors. Key findings included:
1. Regionally, chlorophyll a, total phosphorus, modeled dissolved inorganic phosphorus yield, and the land use classes ‘developed open space’ and ‘low intensity’ were positively related to cyanobacterial blooms, while water clarity, ‘evergreen forest’ and ‘barren land’ were negatively related to blooms. These factors may be useful in predictive modeling and in screening for systems at-risk of developing future blooms.
2. Spill of water over run-of-river dams likely has minimal to no effect on the abundance of phytoplankton and microzooplankton above vs. below such dams in the lower CR.
3. Examination of a 14-year dataset from the lower CR revealed three phytoplankton assemblages distinct to spring/summer, fall, and winter seasons, with notable associations between the fall cyanobacteria/chlorophyte assemblage and elevated temperature and invasive zooplanktonic taxa.
4. The addition of nutrients and zooplankton grazers to the natural phytoplankton assemblage collected from western Washington lakes affected phytoplankton net growth rates in lakes of a low, but not high, trophic state.
Collectively, these results underscore the variable effects that abiotic and biotic factors may have on phytoplankton blooms. These findings further highlight the regional importance of phosphorus in the occurrence of cyanobacterial blooms, the connections between invasive zooplankton taxa, warm water temperatures, and cyanobacteria-dominated assemblages in the CR, and the importance of lake trophic state in phytoplankton response to future nutrient enrichment.
Metrics
38 File views/ downloads
23 Record Views
Details
- Title
- CYANOBACTERIAL BLOOM DYNAMICS IN THE COLUMBIA RIVER BASIN: EFFECTS OF BIOTIC AND ABIOTIC FACTORS
- Creators
- Vanessa Rose
- Contributors
- Stephen M Bollens (Advisor)Stephen M Bollens (Committee Member)Gretchen Rollwagen-Bollens (Advisor)Gretchen Rollwagen-Bollens (Committee Member)John A Harrison (Committee Member)Stephen Katz (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 207
- Identifiers
- 99900581413101842
- Language
- English
- Resource Type
- Dissertation