Although Dreissaena had been introduced already in the 19th century from the Near East it reached the lakes of Upper Bavaria only after WW II. Now it is supposed to have struck for the decisive blow.
In contrast to anodons living in sludgy water beds, zebra mussels only settle on solid substances like stones, branches – and mussel shells. Dreissaena reproduces mainly in the warm season by huge amounts of larvae swimming freely in the water.
Was it maybe the competition for food (planktonic algae) that led to the death of the large mussels? To bring light into this question, experts of the Bayerische Landesamt für Wasserwirtschaft (Bavarian State Office of Water Management) carried out a research project in the past 2 1/2 years in the Starnberger See in co-operation with experts of the Fachberatung für Fischerei (Technical Consulting Agency for Fishery) of the district of Upper Bavaria. For this purpose numerous test and control groups of anodons were observed in enclosures near the shore at almost any time of the year.
While the zebra mussels settling on the anodons in the control group were regularly removed, huge amounts of Dreissaena settled on the test mussels, in particular where the plankton-containing water streamed into the animal. This soon led to the death of the test animals. The examination of fine tissue and biochemical test showed the animals had starved! The small mussels had obviously filtered off the food at the “mouth” of the anodons. Only one consolation remains: the immigrants, too, have enemies: they are eaten by coot, particularly in wintertime. (Source: aqua press Int. 06/2000)
Information & Contact:
Bayerisches Landesamt für Wasserwirtschaft
Denmollstraße 31
D-82407 Wilenbach
Phone +49 881 185 14-0
