- What is it? The zebra mussel (Dreissena
polymorpha) is a tiny (1/8-inch
bottom-dwelling clam native to Europe and Asia. Zebra
mussels look like small clams with a yellowish or brownish
D-shaped shell, usually with alternating dark- and
light-colored stripes. They can be up to two inches long,
but most are under an inch. Zebra mussels usually grow in
clusters containing numerous individuals. Zebra
mussels were introduced into the Great Lakes in 1985 or
1986, and have been spreading throughout them since that
time. They were most likely brought to North America as
larvae in ballast water of ships that
traveled from fresh-water Eurasian ports to the Great Lakes.
- What's the problem? Zebra mussels feed by drawing
water into their bodies and filtering out most of the
suspended microscopic plants, animals and debris for food.
This process can lead to increased water clarity and a
depleted food supply for other aquatic organisms, including
fish. The higher light penetration fosters growth of rooted
aquatic plants which, although creating more habitat for
small fish, may inhibit the larger, predatory fish from
finding their food. This thicker plant growth can also
interfere with boaters, anglers and swimmers. Zebra
mussel infestations may also promote the growth of
blue-green algae, since they avoid consuming this type
of algae but not others.
- How is it spread? It is easily spread by boats
and trailers either in
stored water or physically attached.
- How do I recognize it?
- Looks like a small clam with yellowish or brownish
- Usually have dark and light colored
- Often attached to underwater objects
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