Beyond Eutrophication: Vancouver Lake, WA, USA as a Model System for Assessing Multiple, Interacting Biotic and Abiotic Drivers of Harmful Cyanobacterial Blooms

Abstract

Eutrophication of lakes and reservoirs has contributed to an increase in the magnitude and frequency of harmful cyanobacterial blooms; however, the interactive effects of nutrient availability (eutrophication) and other abiotic and biotic drivers have rarely been comprehensively studied in the field. We undertook an eight-year (2005-2013) research program that assessed the interaction of multiple factors driving cyanobacterial blooms in Vancouver Lake, a large, shallow eutrophic lake in Washington, USA. Our program consisted of nearly continuous monthly or weekly monitoring of water quality and plankton community composition over eight years, as well as multiple zooplankton grazing experiments over three years. We found a relatively consistent seasonal succession of phytoplankton and zooplankton assemblages, and a pattern of interacting factors influencing cyanobacterial bloom dynamics. Typically, a combined effect of decreased dissolved inorganic nitrogen (N), a sudden increase of dissolved inorganic phosphorus (P), and a cascading effect of zooplankton grazing created a 'perfect storm' of conditions that promoted the rapid proliferation of cyanobacteria over the two to three weeks before a bloom. At the blooms' peaks, cyanobacterial carbon biomass reached as high as 20 µg L −1 , with total [chl a] often exceeding 750 µg L −1. In the weeks following the blooms' peaks, [PO 4-P] and [NH 4-N] dropped and copepod feeding rates fell to near zero, whereas microzooplankton grazing rates reached their maxima. Microzooplankton grazing impact, combined with low nutrient availability, then drove down cyanobacteria abundance. Vancouver Lake serves as a model for understanding multiple, interacting drivers of cyanobacterial bloom dynamics in shallow, temperate lakes, and is therefore an important system in which to investigate new questions related to the science and management of harmful algal blooms.

Limnology and Oceanography Bulletin Volume 28 Number 2 May 2019 41–81

“…Unfortunately, eutrophication in the CRE may be increasing the abundance of phytoplankton taxa that form harmful algal blooms (HABs). For example, cyanobacterial HABs are now known to regularly occur in Vancouver Lake (Lee et al 2015;Rose et al 2017;Rollwagen-Bollens et al 2018), a shallow floodplain lake with tidal connectivity to the CRE, and are also becoming an increasing problem in the Willamette River, which flows into the CRE near Vancouver, Washington, and Portland, Oregon (Jacoby and Kann 2007).…”

The effects of run‐of‐river dam spill on Columbia River microplankton

“…Of particular concern is the potential for flow impoundment imposed by dams to enhance cyanobacteria abundance (Paerl & Paul, ). Cyanobacterial blooms are a current problem for freshwater systems globally and have been noted in many impounded riverine (Guo et al, ; Oliver, Dahlgren, & Deas, ; Remmal, Hudon, Hamilton, Rondeau, & Gagnon, ) and adjacent floodplain lake ecosystems (Rollwagen‐Bollens, Lee, Rose, & Bollens, ; Rose, Rollwagen‐Bollens, & Bollens, ). Altered thermal regimes in reservoirs that result in warmer waters and stratification may increase the likelihood of cyanobacterial dominance (Cha, Cho, Lee, Kang, & Kim, ; Paerl & Paul, ).…”

Engaging High School Students as Collaborators in Ecological Investigation of the Columbia River Estuary: Lessons from a Transdisciplinary University–High School Partnership

“…Unfortunately, eutrophication in the CRE may be increasing the abundance of phytoplankton taxa that form harmful algal blooms (HABs). For example, cyanobacterial HABs are now known to regularly occur in Vancouver Lake (Lee et al ; Rose et al ; Rollwagen‐Bollens et al ), a shallow floodplain lake with tidal connectivity to the CRE, and are also becoming an increasing problem in the Willamette River, which flows into the CRE near Vancouver, Washington, and Portland, Oregon (Jacoby and Kann ).…”