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Quagga Mussel

Dreissena bugensis

Invasive mussels infected moss ball products

Zebra and/or quagga mussels have been identified in moss ball products sold in stores in Canada. We urge everyone who may have purchased moss ball products in Canada or online to dispose of them responsibly. Learn how you can do so.

Report it

If you think you have found an aquatic invasive species:

  1. do not return the species to the water
  2. take photos
  3. note:
    • the exact location (GPS coordinates)
    • the observation date
    • identifying features
  4. contact us to report it
Quagga Mussel

Quagga Mussel

Identifying features

  • Average 2 cm, reaching up to 3 cm long
  • Doesn’t sit flat
  • Round in shape
  • Dark concentric rings on shell
  • Pale color near hinge

Similar species (native)

Zebra Mussel (Dreissena polymorpha)

The Quagga Mussel differs from the Zebra Mussel in being larger, rounder and wider. The Quagga Mussel has also a convex ventral surface.

Where it has been found

Quagga Mussels are found to be limited to the southern Great Lakes; Lake Ontario, Michigan, Huron and Erie. They have also been found in the St. Lawrence River and north to Quebec City.

Ecological and economic impacts

  • Quagga Mussel filters water to the point where food sources such as plankton are removed, altering food webs. This also causes clearer water, allowing sunlight to penetrate deeper, increasing growth of aquatic vegetation.
  • Impact fish and wildlife by increasing toxic algal blooms.
  • Females can release up to a million eggs each season which enhances the natural dispersal of this species from locations where it is introduced.
  • Large colonies affect spawning areas, potentially impacting the survival of fish eggs.
  • This mussel species can cause millions of dollars in damage to boat engines, power plant and public water intakes by fouling infrastructure, blocking water flow and costing time and money removing them from affected structures.

Origins and mode of arrival

Native of the middle and south Caspian Sea

The Quagga Mussel, as the Zebra Mussel, was introduced to the Laurentian Great Lakes of North America via ballast water.

Mode of dissemination

This freshwater mussel has rapidly dispersed throughout the Great Lakes region into river systems and smaller lakes due to passive drifting at the larval stage and their ability to attach to the hulls of boats. In addition, this mussel is very prolific and can have profound effects on ecosystems by depleting the biomass of phytoplankton communities, which in turn affect the composition of other communities within the ecosystem.

Government action

Scientific research

Fisheries and Oceans Canada is studying the Quagga Mussel population to improve its understanding of how it reacts and adapts to Canadian conditions.

For further information


  • Therriault, T.W., Weise, A.M., Higgins S.N., Guo, S. and Duhaime, J. 2013. Risk Assessment for Three Dreissenid Mussels (Dreissena polymorpha, Dreissena rostriformis bugensis, and Mytilopsis leucophaeata) in Canadian Freshwater Ecosystems. DFO Can. Sci. Advis. Sec. Res. Doc. 2012/174 v + 88 p.
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