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Oregon Invasive Species Council

May 2010- Zebra and Quagga Mussels
Invasive Species of the Month
Zebra mussel
Photo Courtesy of USGS Nonindigenous Aquatic Species
 May 2010 Invasive Species of the month
 
Zebra mussels:  Dreissena polymorpha
Taxonomic Rank: Bivalvia: Veneroida: Dreissenidae

Quagga mussel: Dreissena rostriformis bugensis
Taxonomic Rank: Bivalvia: Veneroida: Dreissenidae

May calendar events
2010 Oregon Invasive Species Council calendar events
 


What is a zebra or quagga mussel?
Zebra and quagga mussels are closely related freshwater, that typically have a dark and white (zebra-like) pattern on their shells. Zebra and quagga mussels are the only freshwater mollusk species that attach to hard surfaces via hair-like threads. They have thin, fragile shells.
 


Lookalike?
Zebra and quagga mussels could be confused with Asian clams, however, Asian clam shells are thicker, more round and symmetrical, and with distinct ridges.  Zebra mussels seldom grow larger than 1 inch and typically have alternating light and dark strips (but some individuals do not have stripes). Quagga mussels may grow slightly larger than zebra mussels, but generally are abut the same size.  Asian clams can grow to 1.5 inches and are light yellow-brown to dark brown.  Zebra mussel shells are D-shaped, and Quagga mussel shells are more rounded
Where?
Dreissenid mussels are native to the watersheds of the Aral, Azov, Black and Caspian seas of eastern Europe and western Asia.  They were likely introduced to the Great Lakes of North America in the ballast water of cargo ships in the mid 1980’s.  Once established, dreissenid mussels can dramatically alter the ecology of a water body.  Their filtering action enhances water clarity and changes the food web by shifting production from the pelagic to the benthic portions of the water column.  By attaching themselves to the surfaces of other bivalves, dreissenid mussels can starve other freshwater mussels and drive native populations to local extinction.  They can also negatively affect dissolved oxygen levels.

What can you do?
Call 1-800-INVADER or report it online at http://oregoninvasiveshotline.org/ or call the Invasive Species Hotline at 1-866-INVADER (1-866-468-2337). This number is toll free.
 
Clean all aquatic plants, animals and mud from your watercraft, oars and other gear.
Drain your motor, live well, and bilge on land before leaving the waterbody.
Dry your boat and equipment for as long as possible.  Five days is recommended.
 
For more information on cleaning your boat.
 
 
 
 

Risk Assessment
Risk Assessment (pdf format)
Clean Boat Program
Clean Boat Program
Frequently asked questions about the Aquatic Invasive Species Prevention Program (AISPP)

Press release
Press release for May species of the month (pdf format)
All Invasive Species of 2010 calendar
All invasive species of 2010, and 2009