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Quagga Mussel - Dreissena bugensis

Aquatic Invasive Species
Non-native Species

Global Rank: G5
State Rank: SNA
* (see State Rank Reason below)

Agency Status


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State Rank Reason (see State Rank above)
A conservation status rank is not applicable because this species is not a suitable target for conservation activities as a result of being exotic or introduced.
General Description
The quagga mussel is a small, triangular bivalve (<50mm or ~2 inches) that has a rounded angle, or carina, between the ventral and dorsal shell surfaces. Color patterns vary widely with black, cream, or white bands; a distinct quagga morph has been found that is pale or completely white in Lake Erie (Marsden et al. 1996).

Diagnostic Characteristics
Although similar to the zebra mussel (Dreissena polymorpha), the two species can be easily distinguished. When placed on a surface zebra mussels are stable on their flattened underside while quagga mussels, lacking a flat underside, will not sit flat.

Species Range
Montana Range


Range Comments
Native Range: Dreissena rostriformis bugensis is indigenous to the Dneiper River drainage of Ukraine and Ponto-Caspian Sea.
Introduced Range includes the Lake Michigan, Lake Huron, Lake Erie, Lake Ontario, Lake St. Clair, Saginaw Bay, and throughout the St. Lawrence River north to Quebec City. A 2002 survey of Lake Superior did not detect quagga mussel specimens (Grigorovich et al. 2003), but by 2005 the first quagga mussel was confirmed from Lake Superior in Duluth Superior Harbor (Grigorovich et al. 2008b). A few inland occurrences have been reported in Iowa, Kentucky, Michigan, Minnesota, New York, Ohio, and Pennsylvania. In 2004, very limited numbers of quagga mussels were collected from just two of many sample sites on the Ohio River (Grigorovich et al. 2008a).

Adult quagga mussels are mostly sedentary and spend their lives near the area where they first settled as juveniles and attached their byssal threads. Most dispersal takes place through the veliger stage after fertilization where they will passively travel with wind direction or water currents.

The quagga mussel can inhabit both hard and soft substrates, including sand and mud, down to depths of 130 m and possibly deeper. The maximum density of quagga mussels in Lake Michigan is at 31-50 m (T. Nalepa, pers. comm.)

Food Habits
Quagga mussels are prodigious water filterers, removing substantial amounts of phytoplankton and suspended particulate from the water. As such, their impacts are similar to those of the zebra mussel. By removing the phytoplankton, quaggas in turn decrease the food source for zooplankton, therefore altering the food web. Impacts associated with the filtration of water include increases in water transparency, decreases in mean chlorophyll a concentrations, and accumulation of pseudofeces (Claxton et al. 1998).

Quagga mussels inhabit freshwater rivers, lakes, and reservoirs. In North American populations, they do not tolerate salinities greater than 5 ppt (Spidle et al. 1995). Water temperatures of 28°C begin to cause significant mortality, and 32-35°C are considered lethal for Dreissena species (Antonov and Shkorbatov 1990 as cited in Mills 1996). The depth at which the mussels live varies depending on water temperature. They are not generally found in lakes near shore in shallow water due to wave action. The quagga mussel can inhabit both hard and soft substrates, including sand and mud, down to depths of 130 m and possibly deeper. The maximum density of quagga mussels in Lake Michigan is at 31-50 m (T. Nalepa, pers. comm.)

Reproductive Characteristics
Eggs are expelled by the females and fertilized by the males outside the body; this process usually occurs in the spring or summer, depending on water temperature. Optimal temperature for spawning is probably similar to the zebra mussel at 14–16°C. Thousands of eggs can be laid in a reproductive cycle and up to one million in a spawning season. Spawning may last longer in waters that are warm throughout the year.

Dreissena species ability to rapidly colonize hard surfaces can cause serious economic problems. These organisms can clog water intake structures, such as pipes and screens, therefore reducing pumping capabilities for irrigation, power and water treatment plants, costing industries, companies, and communities. Recreation-based activities can also be impacted; docks, buoys, boats, and beaches have all been heavily colonized. Quaggas are able to colonize both hard and soft substrata so their negative impacts on native freshwater mussels, invertebrates, industries and recreation are unclear, but may be worse than zebra mussels which tend to colonize just hard substrates.

Contact information for Aquatic Invasive Species personnel:
Montana Fish, Wildlife, and Parks Aquatic Invasive Species staff.
Montana Department of Natural Resources and Conservation's Aquatic Invasive Species Grant Program.
Montana Invasive Species Council (MISC).
Upper Columbia Conservation Commission (UC3).

Threats or Limiting Factors
Threats to the quagga mussel are minimal, other than reservoir drawdowns and river dewatering which will leave the mussels prone to desiccation. Although a discrepancy exists when comparing temperature tolerance limits of North American and European populations. Water temperatures of 28°C begin to cause significant mortality, and 32-35°C are considered lethal for Dreissena species (Antonov and Shkorbatov 1990 as cited in Mills 1996).

  • Literature Cited AboveLegend:   View Online Publication
    • Antonov, P. I. and G. L. Shkorbatov. 1990. Ecological-physiological characteristics of Dreissena of the Lower Reaches of the Dnieper River. In Vid i yego areale. Biologiya, ekologiya i produktivnost' vodnykh bespozvonochnykh (Species in its distribution range. Biology, ecology and production of aquatic invertebrates); pp. 126-130. Minsk. (InRussian).
    • Claxton, W.T., A.B. Wilson, G.L. Mackie, and E.G. Boulding. 1998. A genetic and morphological comparison of shallow- and deep-water populations of the introduced dreissenid bivalve Dreissena bugensis. Canadian Journal of Zoology 76(7):1269-1276.
    • Grigorovich, I. A., T. R. Angradi, and C. A. Stepien. 2008a. Occurrence of the quagga mussel (Dreissena bugensis) and the zebra mussel (Dreissena polymorpha) in the Upper Mississippi River System. Journal of Freshwater Ecology 23(3):429-435.
    • Grigorovich, I.A., A.V. Korniushin, D.K. Gray, I.C. Duggan, R.I. Colautti, and H.J. MacIsaac. 2003. Lake Superior: an invasion coldspot? Hydrobiologia 499:191-210.
    • Grigorovich, I.A., J.R. Kelly, J.A. Darling, and C.W. West. 2008b. The quagga mussel invades the Lake Superior Basin.  Journal of Great Lakes Research 34(2): 342-350.
    • Marsden, J.E., A.P. Spidle, and B. May. 1996. Review of genetic studies of Dreissena spp. American Zoology 36:259-270.
    • Mills, E.L., G. Rosenberg, A.P. Spidle, M. Ludyanskiy, Y. Pligin, and B. May. 1996. A review of the biology and ecology of the quagga mussel (Dreissena bugensis), a second species of freshwater dreissenid introduced to North America. American Zoology 36:271-286.
    • Spidle, A. P., E. L. Mills, and B. May. 1995. Limits to tolerance of temperature and salinity in the quagga mussel (Dreissena bugensis) and the zebra mussel (Dreissena polymorpha). Canadian Journal of Fisheries and Aquatic Sciences 52:2108-2119.
  • Additional ReferencesLegend:   View Online Publication
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    • Nalepa, T.F. 2010. An overview of the spread, distribution, and ecological impacts of the quagga mussel, Dreissena rostriformis bugensis, with possible implications to the Colorado River system. In: Melis et al. (eds.), Proceedings, Colorado River Basin Science and Resource Management Symposium, Scottsdale, AZ, November 18-20, 2008. U.S. Geological Survey Scientific Investigations Report 2010-5135. pp.113-121. Available:
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Citation for data on this website:
Quagga Mussel — Dreissena bugensis.  Montana Field Guide.  .  Retrieved on , from