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2002 October Report of the Commissioner of the Environment and Sustainable Development

October 2002 Report—Chapter 4

Case Study 4.1—The zebra mussel is a well known invader

The invasion of Lake St. Clair by the zebra mussel in 1988 annihilated 13 native species in that lake and caused the near extinction of 10 species in Western Lake Erie: one of the greatest reductions of biodiversity ever witnessed in North America.

In a 30-kilometre stretch of the Rideau River, just 25 kilometres south of Parliament Hill, the density of these creatures increased from one animal per square metre to 383,000 per square metre in just three years, wiping out all native mussel species in the process.

Zebra mussels are a major fouler of industrial, municipal, and hydroelectric water intakes and outfalls. They cause a decline in water flow and plant efficiency.

Ontario Power Generation estimates that as a direct consequence of zebra mussels, its operating costs increased by between $500,000 and $1 million per year at its Darlington and Pickering nuclear stations, and for fossil fuel stations, about $150,000 per year at Nanticoke, $75,000 per year at Lambton, and $50,000 per year at Lakeview. It has spent over $20 million installing and maintaining chlorine applicators at its Great Lakes facilities and a few inland facilities to deter zebra mussels, and it has spent $13 million on research to reduce or eliminate chlorine. Ongoing operating costs attributable to zebra mussels are not available for the hydraulic stations on the Great Lakes.

These costs and those confronting publicly owned water treatment facilities and other water-intensive industries could ultimately be passed on to homeowners and consumers.

Zebra mussels are also rapidly colonizing in Ontario's inland lakes. Once established there, they will clog water lines and foul piers, engines, and boats. They are also suspected of imparting offensive tastes and odours to drinking water. As many as 160,000 Ontario cottagers could ultimately pay significant costs to counteract problems caused by zebra mussels.

Finally, through their filtering activity, zebra mussels take in hazardous compounds such as polychlorinated biphenyls (PCBs). Fish and waterfowl that eat the mussels carry those poisons into the food chain. This invader has the potential to spread elsewhere in Canada.