Potential factors leading to the formation of cyanobacterial scums in a mesotrophic softwater lake in Ontario, Canada

AbstractWhile the factors linked to the incidence of cyanobacterial blooms are well studied, the specific conditions that facilitate transition of blooms to surface scums are less understood. Three Mile Lake (TML), a mesotrophic, softwater lake in south-central Ontario, Canada, experienced cyanobacterial blooms in 2005, 2006, and 2007, but a surface scum event only occurred in 2005. Our objectives were therefore to (1) determine how phytoplankton change seasonally in relation to water quality and other environmental factors; (2) examine modern and historical water quality and meteorological data to explore possible causative factors of the 2005 surface scum; and (3) examine regional predictions of future climate (temperature and precipitation) from present to 2100 to assess the risk of future cyanobacterial scums. Our evaluation suggests that while high phosphorus concentration is a predisposition for the occurrence of cyanobacterial blooms, meteorological and hydrological conditions play an instrumental ...