... In a scientific paper entitled Algal blooms in Ontario, Canada: increases in reports since 1994, Dr. Jenny Winter and co-authors reported that public reporting of algal blooms in Ontario lakes has increased significantly from 1994 to 2009.
Further investigation by the team revealed that more than half of the reports in any year were for blooms of blue-green algae. This is a concern because some strains, of some species of blue-green algae, are potentially toxic.
...A rise in reports of algal blooms in Ontario is consistent with the observation that algal blooms are increasing in lakes throughout the world. Nutrient enrichment (in other words, increasing additions of phosphorus to lakes) is the leading cause globally, with blooms further exacerbated by climate change.
In Ontario, higher phosphorus concentrations are indeed part of the story. There are lakes near Sudbury, for example, where increased shoreline development and urbanization have contributed to higher phosphorus levels, and consequently, algal blooms.
However, in recent years, blue-green algal blooms have also been observed in lakes with low or declining phosphorus concentrations, suggesting that phosphorus is not the whole story.
Cottage Country Now - www.cottagecountrynow.ca
18 Jan 2012
Cited Journal Article
Algal blooms in Ontario, Canada: Increases in reports since 1994 [free full-text pdf]
Lake and Reservoir Management. 2011; 27:105–112. doi:10.1080/07438141.2011.557765
JG White et al.