Quagga mussels Dreissena rostriformis bugensis (Andrusov, 1897) in the Main River (Germany)

The first record of the quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897) in Germany is described. This species has expanded its distribution area in Europe at a slower rate than the zebra mussel Dreissena polymorpha (Pallas, 1771). Recent records from the Danube in Romania and from an enclosed Rhine-Meuse estuary in The Netherlands, suggest that the MainDanube canal and River Rhine have functioned as the dispersal pathway of the quagga mussel to The Netherlands. The record of this species in the River Main supports this hypothesis. K ey words: Quagga mussel, Dreissena rostriformis bugensis, invasive species, Germany, Main-Danube canal The quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897) was until early twenty-first century a slower invader than the zebra mussel Dreissena polymorpha (Pallas, 1771). Both mussel species originate from the Ponto-Caspian area. The original native range of the quagga mussel is the Lower Dniepr River and Southern Bug River (Son 2007). Over the last few decades, however, the quagga mussel has considerably extended its range in Russia (Orlova et al. 2003, 2004). It reached the River Volga via the Don River and Volga-Don canal (Zhulidov et al. 2004, 2005). Furthermore, it invaded the Great Lakes area of North America probably simultaneous with the zebra mussel (1987), most likely as larvae via ballast water discharge. The quagga mussel was recognized for the first time in the Great Lakes in 1991 (Spidle et al. 1994). D. rostriformis bugensis seems to have an ecology similar to D. polymorpha, but often colonizes deeper water than D. polymorpha (Orlova et al. 2005). However, it is known that at places where D. polymorpha occurs and D. rostriformis bugensis becomes established the latter outcompetes slowly the first species (Orlova et al. 2004). Zhulidov et al. (2004) mentions some characteristics of D. rostriformis bugensis which seems to be important in this process, viz. a better ability than D. polymorpha to cope with low food conditions and high temperatures. Recently, D. rostriformis bugensis was recorded by Micu and Telembici (2004) and Popa and Popa (2006) from the Danube,