ABSTRACT
Dreissena polymorpha, commonly referred to as the zebra mussel. Zebra mussels are relatively small bivalves, reaching 25-35 mm in length, with a high fecundity (>1 million eggs per spawning event) and high dispersal capacity (Ludyanskiy et al. 1993). Native to the Pontocaspian region of Eastern Europe, this species began its range expansion to Western Europe through the opening of transcontinental canal systems during the mid-eighteenth century (Zhadin 1946, Ludyanskiy et al. 1993). Some 150 years later, facilitated by trans-Atlantic commerce, the zebra mussel and a closely related species, the quagga mussel (Dreissena rostriformis bugensis), joined a list of >180 nonnative species introduced into the Laurentian Great Lakes of North America. Currently, D. polymorpha appears more widely dispersed than D. rostriformis bugensis, with reports of established populations across most European nations and within >700 lake and river ecosystems in North America (Benson 2013). While the distribution of the quagga mussel is less well known in Europe (but see bij de Vaate et al. 2013), it has invaded >40 lake and river ecosystems in North America, including many systems in the southwest United States (Benson 2013).
