Dynamics of Harmful Cyanobacteria Blooms in Vancouver Lake, WA
Principal Investigators: Gretchen Rollwagen-Bollens, Stephen Bollens
Students: Jennifer (Duerr) Boyer, Tammy Lee, Vanessa Rose, Katie Sweeney
Funded by: Vancouver Lake Watershed Partnership, Washington State Department of Ecology, Clark County (WA) Department of Public Works, State of Washington Water Research Center, USGS, and National Science Foundation
Award period: 2007-2020
Project Summary:
The frequency and magnitude of freshwater harmful cyanobacterial blooms (CHABs) are expected to accelerate under future climate change, thus understanding the driving mechanisms for CHABs is a pressing need. Over a 14-year period (2006 – 2020) we studied the effects of multiple biotic and abiotic factors on the timing, magnitude, and composition of summertime CHABs in Vancouver Lake, a shallow urban lake in Washington state, USA. Studies included high frequency water quality sampling, multiple series of microzooplankton grazing (dilution) experiments, rotifer and copepod feeding experiments, and incubation experiments testing the interactive effects of enhanced [PO4] and copepod grazing on phytoplankton growth. Our synthesis of these results demonstrates a consistent year-to-year pattern of CHAB dynamics occurring in four overlapping phases. 1) Early Summer: low [PO4] and moderate [NO3], strong copepod predation on microzooplankton (ciliates, dinoflagellates), high diatom growth; 2) Mid- to Late-Summer: Wind-driven PO4 resuspension, copepods and microzooplankton shift diet to diatoms, cyanobacteria bloom; 3) Late Summer: [PO4] decreases, copepods stop grazing, microzooplankton (including small rotifers) consume cyanobacteria, bloom diminishes; 4) Early Autumn: Large predatory rotifers consume microzooplankton, diatoms increase, copepods resume grazing. Our overall results have important implications for bloom management in Vancouver Lake and other shallow lakes, and suggest solutions will come from considering several factors acting in concert.
Publications/Presentations resulting from this project:
Sweeney* K, Rollwagen-Bollens G, Hampton S. (In Press) Grazing impacts of rotifer zooplankton on a cyanobacteria bloom in a shallow temperate lake (Vancouver Lake, WA, USA). Hydrobiologia.
Rose* V, Rollwagen-Bollens G, Bollens S, Zimmerman J. (2021) Effects of grazing and nutrients on phytoplankton blooms and microplankton assemblage structure in four temperate lakes spanning a eutrophication gradient. Water 13: 1085.
Rollwagen-Bollens G, Lee* T, Rose* V, Bollens S (2018) Beyond Eutrophication: Vancouver Lake, WA, USA as a Model System for Assessing Multiple, Interacting Biotic and Abiotic Drivers of Harmful Cyanobacterial Blooms. Water 10(6): 757.
Rose+ V, Rollwagen-Bollens G, Bollens S. (2017) Interactive effects of phosphorus and zooplankton grazing on harmful algal blooms in a shallow temperate lake. Hydrobiologia 788: 345-359.
Lee* T, Bollens S, Rollwagen-Bollens G, Emerson J. (2016) The effects of eutrophication and invasive species on zooplankton community dynamics in a shallow temperate lake. Fundamental and Applied Limnology 188: 215-231.
Lee* T, Rollwagen-Bollens G, Bollens S. (2015) The influence of water quality variables on cyanobacteria blooms and phytoplankton community composition in a shallow temperate lake. Environmental Monitoring and Assessment 187: 315.
Lee* T, Rollwagen-Bollens G, Bollens S, Faber-Hammond J. (2015) Environmental influences on cyanobacteria abundance and microcystin toxin production in a shallow temperate lake. Ecotoxicology and Environmental Safety 114: 318-325.
Rollwagen-Bollens G, Bollens S, Gonzalez A, Zimmerman J, Lee* T, Emerson J. (2013) Feeding dynamics of the copepod Diacyclops thomasi before, during and following filamentous cyanobacteria blooms in a large, shallow temperate lake. Hydrobiologia 705: 101-118.
Boyer* J, Rollwagen-Bollens G, Bollens S. (2011) Microzooplankton grazing before, during and after a cyanobacterial bloom in Vancouver Lake, Washington, USA. Aquatic Microbial Ecology 64: 163-174.