MollBase: here - database of
Schleswig-Holstein
=>> to the MAP 1991 of this
species
Status quo (red dots: data newer than 2000):
Unio crassus crassus is the northern subspecies of Unio crassus, which
inhabits the region of the northern (scandinavian) glaciation. The species is highly
endangered or directly threatened by extinction in most of its area of distribution. In
our region it is strictly limited to running water systems such as brooks or small rivers.
In the large rivers it is extinct as in most other older localities of Schleswig-Holstein,
mostly due to water pollution or straightening of the rivers and brooks. When summing up
the populations of Schleswig-Holstein the species is still living in 10 water systems,
altogether in about 20.000 to 50.000 specimens (R. Brinkmann, persl. comm.).
There are still regions (e.g. the river Alster, north of Hamburg) where the riverbeds are regularily excavated regardless of the highly endangered and strictly protected Unio crassus mussels.
