Shopping cart coated with zebra mussels. From EPA.gov.
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Zebra Mussel
Scientific Name
Dreissena polymorpha
What do Zebra Mussels look like?
Zebra Mussels are less than 50 mm
Colors vary, and stripes may or may not be present on shell
Are usually found attached to other objects
Contain a flat underside Where do Zebra Mussels come from?
Zebra Mussels are from the Black, Caspian and Azov Seas.
Click here for an invasion timeline of the U.S. from 1988 to 2005
By the late 18th and early 19th centuries, zebra mussels had spread to most all major drainages of Europe because of widespread construction of canal systems. They first appeared in Great Britain in 1824 where they are now well established. Since then, zebra mussels have expanded their range into Denmark, Sweden, Finland, Ireland, Italy, and the rest of western Europe.
University of Toledo Ecologist Jonathan Bossenbroek said the Zebra Mussel initially entered the middle U.S. beginning in 1988 through ballast water from international cargo ships.
"The invasion was first noticed in Lake Erie and Lake Sinclair," Bossenbroek said. "From there, the mussels spread to the surrounding great lakes within two years."
Once it was introduced into the native lakes, the mussel was transported through the middle U.S. through a variety of routes. By attaching itself to commercial and recreational boats, it has made its way through shipping routes and by land to water it couldn't normally have reached.
What Effect do Zebra Mussels Have?
Zebra mussels are filter-feeders, animals that strain food and nutrients out of flowing water. This has the effect of reducing pollution in lake systems and allowing for greater sunlight penetration. The positive effects of the Zebra Mussel to Lake Erie ecology can be seen by the reduction of eutrophication of Lake Erie(1) as well as increased water quality(2).
This does not mean that Zebra mussels are beneficial. They are quite a nuisance to people because of their tendency to attach themselves to any man-made structure submerged in the water. The mussels will attach themselves to any stable material, including other species of mussel. This gives them a habit of killing off native shellfish species and becoming the dominant mollusk.
The Zebra mussel also shifts the balance of the ecosystem. In Lake Erie it has been shown to increase the population of Smallmouth Bass, which have benefited from the increased amount of food Zebra mussels provide.
1. Holland, R. E.; Johengen, T. H. & Beeton, A. M., Trends in nutrient concentrations in Hatchery Bay, western Lake Erie, before and after Dreissena polymorpha., vol. 52:1202-1209, Canadian Journal of Fisheries and Aquatic Sciences
2. Garton, D. W.; Berg, D. J. & Stoeckmann, A. M. et al., Biology of recent invertebrate invading species in the Great Lakes: The spiny water flea, Bythotrephes cederstoemi, and the zebra mussel, Dreissena polymorpha. pages 63-84 (in B. N. McKnight editor. Biological pollution: The control and impact of invasive exotic species. ed.), Indianapolis, Indiana.: Indiana Academy of Science.
