Beitrag zur Kenntnis der Molluskenfauna des östlichen Nordharzes

Abstract

Unruh, M.: Notes on the mollusc fauna of the northern Harz Mountains. - Hercynia N.F. 36 (2003): 261–284.Between 1998 and 2003 the mollusc fauna had been investigated in the eastern part of the northern Harz Mountains in 73 terrestrial and 16 limnic habitats. The study mainly concentrated on regions of the mountain Brocken and of the core zone of the National Park “Hochharz”, where rough ecological conditions especially extreme temperatures and a lack of nutrients prevail. Furthermore the valleys of the rivulets Ecker and Ilse had been studied more intensively. Finally known records of species characteristic for the Harz Mountains were checked to receive a picture of the current status of rare species. Altogether 83 species of terrestrial snails, 6 species of water snails, and 8 species of mussels were found. The number of species increases with diminishing altitude, with improving climatic conditions, as well as with improving nutrient availability. It reaches its peak in the nutrient-rich, buffered alder-ash forests and slope-ravine forests of the lower Harz Mountains. In the spruce forests, the spectrum consists only of 3–4 species. The records of montane-silvicole species like Discus ruderatus, Azeka goodalli, and Macrogastra lineolata are especially notable for the Harz Mountains. The occurance of Semilimax semilimax, Columella columella, and C. aspera could be confirmed. Among the species typical for the dry-warm habitats of the Harz foothills the presence of Balea perversa, Sphyradium doliolium, Pupilla muscorum, and P. sterri was confirmed. Within the genus Cochlicopa the occurrence of one further species can be expected because some shells could not be classed with the recorded species. The waters of the Upper Harz region are extremely poor in molluscs due to a lack of ions and strong turbulences. Only a few of the studied still waters at middle altitudes show an average species combination of gastropods and small mussels.