Das Kolonisationsgeschehen auf den jungen Nordseeinseln Memmert und Mellum am Beispiel der Zikaden
(Hemiptera, Fulgoromorpha et Cicadomorpha)
Schlagworte:Auchenorrhyncha, North Sea islands, species turnover, island biogeography
The colonisation process of Auchenorrhyncha on the North Sea dune islands of Memmert and Mellum. – A decade after our first study an inventory control of the Auchenorrhyncha fauna on the North Sea dune islands of Memmert and Mellum was made in 1994 and 1995. On both islands the assessed species number has remained nearly constant. On Memmert 12 species were recorced as new, among them two new records for the chain of East Frisian islands. For Mellum there were 10 new records. With a rate of 18 and 20 %, respectively, the species turnover is low compared to other arthropod groups. These findings are mostly due to temporary colonist species. The remaining part can be assigned to changes in habitat parameters (particularly an increase in shrub growth) or flaws in the sampling. However, a stochastic species turnover in terms of the equilibrium theory cannot be substantiated.