Zebra Mussel - Chesapeake Bay Program

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Background

Zebra mussel photo courtesy Amy Benson / USGS Zebra mussel (Dreissena polymorpha) is a temperate freshwater bivalve species native to the Black and Caspian seas of Russia and the Ukraine. The mussels made their way to Western Europe through canals and inland waterways that were used for trade during the Industrial Revolution. Zebra mussels first arrived in the United States around 1985, when transoceanic ships released ballast water into Lake St. Clair of the Great Lakes. The ballast water, which is taken into a ship's hold so that it can maintain its weight after it has unloaded its cargo, likely contained veligers and adult zebra mussels.

Adult zebra mussels measure between 0.5 and 3.5 cm in length. The mussels' shells are characterized by dark brown-and-cream concentric banding, which gives the animal its "zebra"-like appearance. Like many successful invasive species, the zebra mussel is prolific. Females can release 30,000 to one million eggs per year. Spawning can begin in May and last until October. Adult mussels eventually generate a tuft of fibers called a byssus, which will attach to most any surface such as rock, fiberglass, rubber, vinyl, wood, metal or glass. Concentrated beds of mussels can contain up to 100,000 mussels per square meter. Additionally colonization can occur at varying depths.

The Problem

The colonization patterns of zebra mussels damage water intake structures such as power and municipal water treatment plants. It is estimated that the zebra mussel has cost the power industry $3.1 billion since 1993.
Attachment to boat motors, docks, buoys and pipes have affected recreation industries.
Recreational beaches that become littered with the shells also are affected; the sharp-edged shells can harm bare feet.
Zebra mussels are hearty filter-feeders that can significantly reduce the supply of microscopic zooplankton, which many forage fish depend upon.
Zebra mussel control is costly!

The Solution

Due to the high cost of coping with the impact of zebra mussels, the spread of zebra mussels is a very serious matter. Due to their potential threat and damage, the Chesapeake Bay Program designated the zebra mussel as a high priority species and Program partners are developing a plan to prevent their spread.

Although zebra mussel populations are not widespread in the Bay watershed, several isolated populations have been discovered. Small populations of zebra mussels have been found in quarries in Virginia and Pennsylvania as well as a lake in New York that has an outlet stream to the Susquehanna River. Resource managers are currently working to eradicate the zebra mussel populations from these locations to prevent further spread.

With proper attention and education, the spread of zebra mussels can be stopped. Boat owners and SCUBA divers must be sure to thoroughly clean their boats and equipment before leaving a waterway that may contain zebra mussels.

How YOU Can Help:

Remove any visible mud, plants, fish or animals before transporting equipment.
Drain at the site of origin bilges, live wells and any other compartments that could hold water.
Clean and scrub boat hulls, anchors and trailer. Hose equipment with hot and/or high pressure water.
Clean and dry anything that came in contact with water (Boats, trailers, equipment, clothing, dogs, etc.)
Never release plants, fish or animals into a body of water unless they came out of that body of water.
As an added precaution, allow all equipment (dive gear, boats, etc.) to dry thoroughly before using it again at another site; five days if possible.

Other Sites of Interest:

Zebra mussel photo courtesy Amy Benson / USGS

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For more information, contact the Chesapeake Bay Program Office:
410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800) YOUR-BAY / Fax: (410) 267-5777.