Thesis
Microzooplankton grazing on cyanobacteria in Vancouver Lake, Washington, USA
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/101577
Abstract
Many studies have examined microzooplankton (20-200 µm) grazing impacts on phytoplankton using dilution experiments in marine systems, but few have been conducted in shallow temperate lakes. I conducted 16 dilution experiments (April 2008 - January 2009) to estimate microzooplankton grazing and intrinsic phytoplankton growth rates before, during and after a cyanobacteria bloom in Vancouver Lake, Washington, USA. Intrinsic phytoplankton growth rates were low in early spring (0.41 d-1), then increased over the spring to a maximum (1.19 d-1) in May 2008, before declining to zero and becoming negative in June and July 2008, just prior to the bloom. Phytoplankton growth rates rose as the bloom progressed through August and September 2008, reaching rates >1.0 d-1, then declined through the fall and winter. Microzooplankton grazing rates were low (0.29 d-1) in the spring, then became substantially negative (–1.0 to –1.50 d-1) in the month preceding the initial chlorophyll a bloom. During the bloom in late summer, grazing rates quickly increased to a maximum of 0.75 d-1 and remained high as the bloom declined. Microzooplankton grazing specifically on cyanobacteria was high in the spring (0.97 d-1), negative just prior to the bloom (-0.66 d-1 to -0.97 d-1) in summer, and positive but low in the fall (0.31-0.68 d-1). Microzooplankton grazing appeared to influence the v formation and decline of the cyanobacteria bloom. The negative grazing on cyanobacteria in the summer may have been due to preferential grazing on other co-occurring prey, thus enabling the bloom to form, while higher grazing rates on cyanobacteria in the fall likely contributed to the decline of the bloom. These findings show that microzooplankton can potentially control cyanobacteria blooms through grazing and may help us to understand food web dynamics of plankton assemblages in large, shallow lakes.
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Details
- Title
- Microzooplankton grazing on cyanobacteria in Vancouver Lake, Washington, USA
- Creators
- Jennifer Christine Duerr
- Contributors
- Stephen M. Bollens (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525389001842
- Language
- English
- Resource Type
- Thesis