The Wadden Sea in the Netherlands: Ecotopes in a World Heritage Barrier Island System

Publisher Summary The Wadden Sea forms the coastal strip bordering the North Sea in NW Europe. Along most of its length it is separated from the North Sea by a string of barrier islands. The system consists of many recognizable geomorphic units (here called ecotopes), such as islands, high sandbanks, sand dunes, salt marshes, subtidal and intertidal sand and mudflats, and channels of different depths and widths. The Wadden Sea intertidal flats are characterized by their location within tidal basins behind barrier islands. They contain a sequence of large to small ebb and flood gullies. The flats near the inlet are predominantly sandy and those near the coast are muddy. The Wadden Sea is a mesotidal barrier island system that only has minor river influences, fringing the flat and low-lying NW European coastal plain. In contrast to most mudflat systems in the world, the Wadden Sea area has not been formed as a river delta, nor is part of an estuary or bay, although there are some estuaries and bays within the Wadden Sea itself. The Wadden Sea consists of a number of very different habitats, ranging from islands to intertidal flats, salt marshes, and gullies and channels. Depending on the mapping scale, these can be further subdivided into smaller recognizable units. For management purposes, it is essential that the proper scale is adhered to when discussing specific issues. For mapping, it is important that elements can be distinguished based on discernable characteristics. When a single organism uses different habitats for different purposes, simple correlations between habitats and the occurrence of species are confounded.