Macrofaunal communities in the Wichter Ee, a channel system in the East Frisian Wadden Sea

Abstract

In March and September 1998 we investigated the macrobenthos of the Wichter Ee, a channel system in the East Frisian Wadden Sea between the islands of Baltrum and Norderney. Grab samples were taken at 20 stations scattered over the whole area. The macrofauna was assessed in terms of numerical abundance and biomass (AFDW). A total of 95 macrobenthic taxa were found, with a total mean biomass of 10.6 g/m2. The investigation focused on the temporal and spatial variability of the macrofaunal assemblages by means of community statistics such as cluster analysis and MDS ordination. Three macrofaunal communities could be determined in the Wichter Ee: community 1, occurring at the highly dynamic sandy areas of the inlet, was characterised by species such asBathyporeia pelagica, Scolelepis squamata, Hailstorms arenarius andParaonis fulgens. Community 3 was found at the inshore, more silty areas of the channel system and comprises species such asHeteromastus filiformes, Tubificoides benedeni, Tharyx killariensis orScoloplos armiger andSpio martinensis. Community 2 could be described as a “transition zone”, as its species inhabit the edges of the inlet as well as the smaller channels. Species found includedCapitella spp.,Scoloplos armiger, Spio martinensis, but alsoScolelepis squamata andMagelona johnstoni. The observed community structures were discussed according to the extreme hydrodynamics prevailing in this rather shallow habitat.