Research Showcase Gallery (Poster 2066)

Grazing Impacts of Rotifer Zooplankton in a Seasonally Cyanobacteria-Dominated Lake

Abstract

Vancouver Lake in western Washington is one of many lakes characterized by annual and often toxic cyanobacteria (harmful algae) blooms. Phytoplankton and cyanobacteria are the primary producers of lake systems, and the foundation on which zooplankton grazers, like copepods or rotifers, can survive. Thus, toxic blooms may be controlled top-down by these micrograzers, which is information relevant to resource managers and the public alike. Previous studies have shown copepod grazing to influence bloom formation, and bloom decline to be driven in part by microzooplankton community grazing. However, we don't understand the individual roles of particular micrograzers such as rotifers. To address the role of rotifers, we are conducting feeding incubations with water collected from Vancouver Lake. Preliminary results show that rotifers have a mild grazing effect on phytoplankton and cyanobacteria only after the peak of a bloom, while the whole microzooplankton community has a large impact both before and after the peak. This seems to suggest that other non-rotifer microzooplankton such as ciliates or dinoflagellates may be responsible for the majority of bloom suppression in both spring and fall. Further microscopical analysis of samples will elucidate which plankton species were present in the lake during each experiment, and which phytoplankton taxa rotifers had been preferentially feeding on. Additionally, due to an unexpected shift in the timing of the 2019 bloom cycle, supplemental experiments will be performed during spring 2020 to complete our understanding of seasonal dynamics related to cyanobacteria blooms.


About the Presenter

photo of kathryn sweeney

Kathryn Sweeney

Kathryn (Katie) Sweeney is a second-year graduate student in the Aquatic Ecology Lab at Washington State University Vancouver, WA. She studies the feeding ecology of microorganisms in Vancouver Lake and how they interact with harmful algal blooms. After earning her M.S. degree in Environmental Science she hopes to continue a career in aquatic conservation and public service, which has been her goal since she was a young child growing up in upstate New York. Spurred by her childhood adventures and her previous positions in ecology, she is excited to continue exploring nature’s wonders both at home and abroad.