Die historische und aktuelle Bestandssituation der halobionten und halophilen Laufkäferfauna (Coleoptera, Carabidae) im Gebiet der Mansfelder Seen westlich von Halle/Saale (Sachsen-Anhalt).

Abstract

Trost, M.: The historic and recent status of the halophilic and halobiontic ground beetle fauna (Coleoptera, Carabidae) in the Mansfeld lake area in the west of Halle/Saale (Saxony-Anhalt). – Hercynia N.F. 39 (2006): 121–149.The area around the Mansfeld Lakes (Süßer See and [former] Salziger See) in the south of Saxony- Anhalt (Germany) near the city of Halle/Saale is rich in inland salt sites, which are well known for their specialized and rare ground beetle fauna. The presented paper deals with the course of habitat changes from the early 19th century on, their causes and effects on the ground beetle fauna and tries to assess the present conservational status of the salt carabid fauna. The data were obtained from historic records of the fauna and habitat conditions as well as recent research in most salt sites of the area. For interpretation of the data a regional established habitat model has been applied. Copper mining in the Mansfeld area severely interfered with the hydrogeological regime for several hundred years, resulting in the exhaustion of the Lake Salziger See and the decline of the major salt sites at the end of the 19th century, extremely salty Salicornia-saltmarshes respectively. At the same time new secondary salt habitats came into existence, albeit temporarily, under the influence of salty mine water at other localities. Halobiontic species vanished from deteriorating salt sites, at the same time partly colonising new secondary habitats. On the whole, continuing changes in land use and hydrology led to the regional loss of five particularly stenotopic carabid species exclusively inhabiting extremely salty Salicornia-saltmarshes due to a severe shortage of their habitat between the end of the 19th and the middle of the 20th century. The availability of those extreme salt habitats improved not until the development of some new secondary salt sites around vast potash mining dumps in the 1960s. From the 1970s on, the wide ranging rise of the groundwater level led to new salt influenced wet habitats in the basin of former Lake Salziger See. Those processes proved to be favourable for halophilic and halobiontic ground beetles thus stopping the negative overall tendencies of their populations in the area. At the present time characteristic species of the saltiest habitats (i.e. Salicornia-saltmarshes) are best represented in the now very well established secondary salt habitats near the potash dumps, whereas being underrepresented in the Sites of Community Interest according to the European Union habitats directive in the vicinity. Because of the importance of those secondary salt sites for the ecological coherence of the Natura 2000 network and, in particular, because of the considerable dependency of the regional halophilic and halobiontic ground beetle fauna on secondary habitats, a higher protective status of the major sites around potash dumps is recommended.