Early and late cyanobacterial bloomers in a shallow, eutrophic lake

Abstract

Cyanobacterial blooms present challenges for water treatment, especially in regions like the Canadian prairies where poor water quality intensifies water treatment issues. Buoyant cyanobacteria that resist sedimentation present a challenge...

Blooms and flows: Effects of variable hydrology and management on reservoir water quality

“…Conductivity may be important in prairie systems where sulfate is the dominant anion and summer total nitrogen (TN):total phosphorus (TP) is low (Joshi & Jackson, 2022; Marino et al, 1990). This is because low TN:TP is often associated with N‐fixing cyanobacteria abundance (Higgins et al, 2018), which are frequently dominant in Buffalo Pound and other prairie lakes (Painter et al, 2022). Nitrogenase synthesis by N‐fixing cyanobacteria requires micronutrients, including Mo, typically in the form of molybdate (MoO 4 2− ) in oxygenated waters.…”

“…The “managed” scenario (L. Diefenbaker dominated flow); however, may create worse blooms in terms of magnitude—we observed higher phycocyanin in the managed flow years (2016–2020)—but this observation requires further study to understand why. We know the midsummer bloom in a managed flow year is typically composed of N‐fixers and is associated with toxin production, particularly microcystins (Painter et al, 2022); however, we lack such temporally resolved knowledge of the cyanobacterial community in the earlier years. It is possible that the chemistry of water from upstream Lake Diefenbaker is more conducive to cyanobacterial proliferation.…”

“…Harmful cyanobacterial blooms are a widespread issue both globally and across the prairies with frequent midsummer blooms occurring in many lakes (Hayes et al, 2020; Painter et al, 2022; Pick, 2016). High P availability from prairie soils contributes to high productivity in lakes and reservoirs.…”

Blooms and flows: Effects of variable hydrology and management on reservoir water quality

“…The "managed" scenario may create worse blooms in terms of magnitude -we observed higher phycocyanin in the managed flow years (2016 to 2020) -but this observation requires further study to understand why. We know the mid-summer bloom in a managed flow year is typically composed of N-fixers and is associated with toxin production, particularly microcystins (Painter et al, 2022); however, we lack such temporally resolved knowledge of the cyanobacterial community in the earlier years. It is possible that the chemistry of water from upstream Lake Diefenbaker is more conducive to cyanobacterial proliferation.…”

“…Water quality issues are especially challenging in prairie systems where soils are naturally phosphorus (P) rich and agriculture dominates watersheds (Schindler and Donahue, 2006;Schindler et al, 2012). Prairie lakes and reservoirs are often bloom-prone with frequent mid-summer blooms of harmful cyanobacteria (Pick, 2016;Hayes et al, 2020;Painter et al, 2022). Yet, water quality issues remain understudied and flow management for water quality is rarely prioritized.…”