Data for "Extreme midsummer rainfall event drives early onset cyanobacterial bloom"

The
prevalence and increasing global distribution of cyanobacteria-dominated
harmful algal blooms is strongly associated with changing climatic patterns and
local biogeochemical and hydrological processes. Changes to precipitation
frequency and intensity, as predicted by current climate models, are likely to
alter bloom development and composition due to nutrient fluxes and water column
mixing. However, few studies have directly documented the effects of precipitation
events on cyanobacterial composition, biomass, and toxin production. In this
study, we describe an early-initiated cyanobacterial bloom in Conestogo Lake, a
eutrophic flood control reservoir located in southwestern Ontario, following
heavy rainfall and subsequent flooding within the catchment. A surge in
bioavailable phosphorus resulted in biomass increases of Aphanizomenon
flos-aquae throughout the reservoir approximately 2 weeks post-flooding.
Anabaenopeptin-A and three microcystin congeners (microcystin-LR, -YR, and -RR)
were detected at varying levels across sites during the bloom period, which
lasted between 3 - 5 weeks. In addition, each of the three sampled sites varied
in physical and chemical properties throughout the sampling campaign suggesting
different eco-zones within the reservoir that may be influenced by flow.
Together, these findings indicate that water column mixing and phosphorus
concentrations were the key drivers for the early cyanobacterial bloom in
Conestogo Lake and further highlight the complex relationship and variability
within reservoir systems. Therefore, effective management goals and mitigation
strategies for bloom-related water quality impairment must be both responsive
and adaptive to the complexity of drivers affecting blooms.