Background:

Periphyton is the community of organisms that grow on surfaces in shallow water near the shore of lakes. The dominant organism is normally an attached alga or plant. However, it is a complex community with bacteria, cyanobacteria, fungi, and invertebrates all having functional roles within the community.

In Lake Ontario the dominant attached alga is Cladophora. In the 1960's and 70's this alga caused serious problems in the near shore zone. It had explosive growth, which detached and fouled local beaches at the peak of the summer recreational season. Research at that time showed that Lake Ontario was receiving an excess of phosphorus, which normally limits Cladophora growth in the shallow, well-illuminated near shore zone. Measures to reduce phosphorus loading included changes in detergent formulations and phosphorus removal at sewage treatment plants. Together these measures brought the excess growth of Cladophora under control during the 1980's.

Lake Ontario is a lake in transition. The introduction of zebra mussels and other species are changing the ecology of the lake. The population on the Ontario side of the lake is growing rapidly with close to 6 million people now living within the drainage basin. This population, and the related commerce, is inevitably producing pressures on the lake.

Since 2000, the excessive growth of Cladophora is again becoming a problem along the north shore of Lake Ontario. Although current levels remain relatively low compared to those measured in the 1960s and 1970s, prior to effective phosphorus control in the Great Lakes basin; the fouling of beaches has resulted in increased complaints from residents.

At the request of the member water utilities, a new research initiative, related to attached algae in Lake Ontario, began in 2002. This research is aimed at a better understanding of the factors that influence the growth of Cladophora and the related periphyton in Lake Ontario with the ultimate goal of providing advice on possible control methods. This research is being carried out at the University of Waterloo with a grant from the OWWRC and support from the National Water Research Institute and Ontario Ministry of the Environment.

Click here for the Summary Report (June 2007) on the Attached Algae research.

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