COMMENTARY — Copper, zebra mussels don’t mix

A university of Toronto study has found that copper surfaces are effective in preventing zebra mussel attachment.

Working at a Lake Erie test site, Professor Jan Spelt of the U of T’s mechanical engineering department and his fellow investigators are measuring the ability of zebra mussels to attach and adhere to various surfaces. Zebra mussels are small — the newly hatched ones are less than one millimetre in length — so it is difficult to prevent them from entering water-intake pipes. Chlorination has been one method of controlling the zebra mussel population, but environmental concerns have led to strict limits on chlorine levels.

The test site is at the Nanticoke generating station near Port Dover, Ont., an area with a large zebra mussel population. Researchers have submerged six panels containing several hundred test plates, measuring 8×16 cm each. The test plates are made of a wide variety of materials, including copper and five different copper alloys.

“After two years in Lake Erie, the test plates of copper and some copper-nickel alloys remained free of mussels,” Spelt explained. “When the concentration of the copper in test plates becomes too low, zebra mussels are able to attach and live on those plates. We’re currently determining the minimum copper concentration that will prevent attachment.

“Copper has a long history of success in preventing the attachment of organisms in salt water environments, and we are seeing that this is true in fresh water as well. But before municipal plants switch to copper pipes as a solution to the zebra mussel problem, we need to investigate the long-term effects. For example, how well does copper perform after being submerged for a long time?”