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Attack of the zebra mussels

Broadcast Date: July 6, 1990

The ecological balance of the Great Lakes is at risk thanks to the infestation of zebra mussels (Dreissena polymorpha), an exotic freshwater shellfish native to the Caspian Sea region of Asia. The mussels are believed to have been introduced into the Great Lakes system in the 1986 by intercontinental freighters along the St. Lawrence Seaway. Now, they number in the billions (each female can produce as many as 40, 000 eggs) and are changing the ecology of the Great Lakes by filtering microscopic life from the water.

They're also causing havoc by sinking buoys and sticking by the thousands to water intake pipes, thus threatening water supplies for millions of Canadians. The mussels lay their eggs near the pipes of electric generating stations and when a large population develops, the pipes often become clogged and unusable. In this CBC Television clip, Midday talks to Gerry Mackie, a zoologist at the University of Guelph, about the potential long-term damage of these tiny invaders.

Attack of the zebra mussels

• Zebra mussels caused millions of dollars in damage to boats and power plants in Canada and the United States, forcing scientists to investigate ways to combat them. Researchers at Purdue University came up with an interesting and effective method: radio waves. Scientists at the Indiana-based University used low-energy radio waves to zap the mussels. They exposed 1, 000 mussels in giant fish tanks to the radio waves. All of the mussels died within 40 days.

• A study conducted in 2001 at Laval University discovered that the mussels were not only transported into the Great Lakes by intercontinental boats, but also attaching themselves to aquatic weeds that get entangled on the bottom of local recreational boats and boat trailers.

• The study showed that zebra mussels have up to seven ways of attaching themselves for transport: to the boat's exterior, anchor, entangled aquatic weeds, engine cooling system, bilge water, live wells, bait buckets. The study concluded that it wasn't necessarily the number of recreational boats on a lake, but instead the regularity of ‘promiscuous' behaviour that contributes to the severity of zebra mussel infestation.

Attack of the zebra mussels

Medium: Television

Program: Midday

Broadcast Date: July 6, 1990

Guest(s): Gerry Mackie

Host: Brent Bambury, Valerie Pringle

Duration: 6:27

Last updated:
March 25, 2003