The spiny water flea was first found in Lake Ontario in 1982 and by 2003 it had invaded at least 57 inland lakes and lake systems in Canada. Its spread has been facilitated because it can produce resting eggs able to survive adverse environmental conditions (such as drying out or being eaten by fish), and because humans transport the eggs on their fishing gear and pleasure boats.
Professor Norman Yan of Ontario's York University has demonstrated that predation by the spiny water flea causes an average loss of three zooplankton species. Thus, as the species spreads, it could cause loss of thousands of populations of zooplankton species in Ontario alone.