Quagga mussel
Quagga - Zebra Mussel ( Dreissena rostriformis bugensis )
The quagga zebra mussel ( Dreissena rostriformis bugensis ) is a subspecies, which belongs to the family of zebra mussels. Partly it is also regarded as a separate species ( Dreissena bugensis ). Originally distributed in the tributaries of the Black Sea, they in Europe and North America occurs as neozoon.
Features
The shape, size and coloring of the shell resembles that of the zebra mussel. However, the quagga zebra mussel is characterized, in contrast to the zebra mussel, by the absence of a sharp keel, and by a very rounded ventral side. The coloration is very variable. It come before dark brown individuals who are striped partly light brown, but very dark and almost white copies. The mean shell length was measured in copies am Main, was 17.2 mm, the largest individuals ( from the Danube ) had a shell length of 32.3 mm.
Way of life
The quagga zebra mussel is a freshwater mussel, which also tolerates brackish water with low salt content. The mussels attach themselves with their byssus threads firmly on hard substrate, usually on the underside of rocks, or concrete walls. The animals are dioecious and have planktonic larvae.
Dissemination
As original distribution area of the Quagga - Zebra Mussel the estuaries of the rivers Southern Bug, Dnieper and Inhulez on the Black Sea (Ukraine ) will be accepted. The mussel has spread out probably starting in the 1940s, thence initially in Eastern Europe ( Russia). In the 1990s, it was probably about the shipping, to North America (especially in the Great Lakes region, but also west of the Rocky Mountains ) introduced. Today it is widely used in various regions of Europe (Romania, Bulgaria, Hungary, Austria, France, Netherlands and Germany ). In Germany, the quagga zebra mussels in 2005 was detected for the first time. So far, she has settled following rivers: Danube, Main-Danube Canal, Main, Rhine, Mittelland Canal, and more connected channels ( Wesel- dates channel, Dortmund -Ems Canal, Rhine -Herne Canal, dates - Hamm Canal, Elbe- Lübeck Canal ).
System
Within the genus Dreissena the quagga zebra mussel belongs together with its sister taxon in the subgenus Dreissena rostriformis rostriformis Pontodreissena. They are the sister group to the subgenera Carinodreissena and Dreissena.
Problem
While the closely related Dreissena rostriformis rostriformis has a rather restricted area of distribution in the Caspian Sea, the quagga zebra mussel spreads currently from getting on. In the newly settled regions, they can have a significant part of the biomass make up and seems to displace the ecologically similar zebra mussels there. With the help of their byssus threads they can grow mussels and other molluscs and thus presents a problem for these organisms represents the overgrown animals are restricted in their movement and can, for example, not close their shells.