Invader Profile

From May 10, 1990 (update #1)

Zebra mussels (Dreissena polymorpha) are marble-size, barnacle-like freshwater molluscs that colonize almost any underwater structure with a hard surface, including water intake pipes, boat hulls, harbor pilings, navigation buoys and commercial fishing gear. Colony densities range up to hundreds of thousands per square yard. Already infesting Lakes St. Clair, Erie and Ontario, zebra mussels are expected to spread throughout the other Great Lakes and eventually to inland lakes and waterways. Events in Lakes St. Clair and Erie indicate this organism has tremendous destructive potential. It is also clear that massive infestations can occur with little warning, since the zebra mussel was virtually unknown in the Great Lakes just two years ago. Lakeside power plants, industries and municipalities with water intakes in the nearshore region are likely to suffer the most serious and costly encrustations. One Great Lakes water utility has estimated that it may cost $50 million to $100 million a year to scrape the mussels from its intakes, and many Great Lakes water intake pipes will have to be redesigned to provide more access points for monitoring and removing the mussels. Possible controls include the use of intake screens, electrostatic filters, flushing with hot water and chlorination. In some cases it may be necessary to install secondary intake pipes so the primary pipes can be shut down for cleaning. The effects of zebra mussels on the ecosystem are unknown at this time. They are capable of colonizing spawning reefs and filter-feeding tremendous quantities of algae, which may adversely affect the reproduction success of certain fish. Some reports indicate they will also colonize submergent plants. On the other hand, diving ducks, lake sturgeon and certain other fish readily feed on the mollusc. Despite the "horror story" coverage zebra mussels have received lately in the news media, Europeans have coexisted with zebra mussels for nearly two centuries. But the immense expense, disruptions and inconveniences that they may cause here is a legitimate concern not only for the Great Lakes region, but for the nation.

ID: 19900510-2.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.