First stages of arthropod colonisation of a sand bank island in the German Wadden Sea

Abstract

In 2007, we surveyed the arthropod fauna of Kachelotplate, a newly emerging sandbar west of Juist Island, southern North Sea. Sampling methods involved pitfall traps, coloured pan traps, targeted searches as well as sampling for predetermined time intervals by means of a pooter and sweep nets. The survey yielded a total of 46 species, including 21 species of beetles, 10 species of flies, 8 hymenopterid species, 5 species of spiders and 2 species of bugs. More than half of the species were recorded from embryonic dune sites. The arthropod assemblage of the driftline was mostly composed of beetles. Based on their known habitat requirements, 22 species appear capable of permanent establishment on Kachelotplate. However, the storm surge events in 2007 have prevented most of these species from establishing permanent populations. Immediately after the floods, the sandbar was recolonised by anemochoric or anemohydrochoric dispersal. In order to achieve a more comprehensive picture of the primary colonisation process during the formation of the island and to determine fluctuations in numbers and composition of the species assemblages, a long-term field study over several years is required.