Water Resources Research Act Program

Details for Project ID 2009WA264B

Understanding Controls on Cyanobacteria Blooms: Vancouver Lake as a Model System

Institute: Washington
Year Established: 2009 Start Date: 2009-03-01 End Date: 2010-02-28
Total Federal Funds: $27,455 Total Non-Federal Funds: $55,165

Principal Investigators: Gretchen Rollwagen-Bollens, Stephen Bollens

Project Summary: The increasing incidence of noxious cyanobacterial blooms in freshwater lakes and rivers is of great concern to water resource managers, as well as to the public whose use and enjoyment of these environments may be impaired or prohibited as a result. Vancouver Lake, in Clark County, WA, is a large, shallow lake in the lower Columbia River floodplain that is popular with the local community for swimming, boating and other recreational activities, as well as an important habitat for wildlife. However, Vancouver Lake has experienced numerous summertime cyanobacterial blooms, often necessitating closure of the Lake to swimming and other recreational use. Concern for the health of Vancouver Lake among local, state and federal agencies, private businesses, and citizen groups led to the formation in 2004 of the Vancouver Lake Watershed Partnership (VLWP). As part of its mission to better understand the processes that influence cyanobacteria blooms in Vancouver Lake, the VLWP recently partnered with the Aquatic Ecology Laboratory at Washington State University Vancouver (Bollens and Rollwagen-Bollens, Principal Investigators) to undertake a biological assessment of the Lake. This assessment involves quantifying the distribution, abundance and composition of the planktonic organisms (i.e. algae, cyanobacteria, protozoa and zooplankton) in Vancouver Lake, as well as collecting a wide range of water quality data, including temperature, conductivity, turbidity, light penetration, and nutrient concentrations, over the annual cycle. In summer 2008, the assessment project also included a limited number of experiments to measure the grazing rates of zooplankton consumers, in conjunction with measurements of cyanobacterial and algal growth rates. In this proposal to the State of Washington Water Research Center (SWWRC), we intend to expand on this biological assessment by measuring the dynamics and rate processes mediating trophic interactions among plankton populations in the Lake, in particular the balance of cyanobacterial and algal growth rates with the grazing rates of zooplankton consumers, during the winter/spring – thus allowing us to evaluate the role of grazers in modulating cyanobacteria populations over a full annual cycle. Rapid increases in algal or cyanobacterial biomass, or “blooms”, are ultimately the result of an imbalance between factors promoting algal growth and factors leading to algal mortality or loss, predominantly herbivorous grazing. Growth rates of cyanobacteria and algae may often be predicted based on nutrient levels, light availability, etc. However, cyanobacterial/algal losses due to grazing are highly variable and dependent upon the composition of the consumer community. We propose to conduct a series of experiments from March – June 2009 to measure algal growth rates and grazing rates of several categories of zooplankton consumers, and to determine how the balance of these two rate processes compare prior to the onset of a bloom. The results of these experiments will provide critical information in developing a predictive model for understanding how and why these cyanobacteria blooms develop and persist, and provide clues toward the development of approaches to limit future blooms in Vancouver Lake and elsewhere. This proposed project will serve as the basis of a master’s thesis by Ms. Jennifer Duerr, a WSU Vancouver graduate student in the Aquatic Ecology Laboratory, as well as provide support for an undergraduate student. In addition, this project will support Dr. Rollwagen-Bollens, an Assistant Clinical Professor in her first three years of an academic appointment at WSU.