Comparative analysis of the developmental stage of uninhabited dune islands in the southern North Sea based on their spider- and ground beetle-fauna

Between 1984 and 1992 the colonization of spiders and ground beetles was investigated on the uninhabited dune islands Luetje Hoern, Memmert, Minsener Oog, and Mellum (FRG, Lower Saxony, East Frisian islands) lying off the German North Sea coast. On the basis of the present results the developmental stage of these small islands is compared with numerous primary habitats on the old East Frisian island Norderney. The spatial distribution patterns are ascertained for spiders with a correspondence analysis. A community succession occurred from salt marshes and fore-dunes on Luetje Hoern to yellow dunes on Minsener Oog and to different grey dune elements on Norderney. A cluster analysis for spiders and ground beetles results in a high similarity between Memmert/Mellum and salt marshes and fore-dunes on Luetje Hoern, Minsener Oog, and Norderney, respectively between numerous older dunes on Norderney. On the basis of so-called 'leading communities' for both arthropod groups correspondences of about 50% were found between salt marshes on Luetje Hoern and Norderney. The correspondence between dune habitats on Minsener Oog and grey dunes on Norderney was low with 15% (spiders) and 21% (ground beetles).