2. The Wadden Area: the general context According to the “Convention on Wetlands of International Importance”, better known as the Ramsar Convention (Iran, 1971), wetlands can be defined as “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres.” As such, all wetlands have two characteristics in common: water and earth. Because of their crucial position between water and land, wetlands provide humankind with important biological resources. Wetlands International – a global organisation that works to sustain and restore wetlands and their resources for people and biodiversity – even asserts that no other type of ecosystem is as important to millions of migratory birds, fish, amphibians, insects, plants and trees as wetlands. Wetlands also perform many functions that are (potentially) very valuable, not only in ecological but also in economic terms. Following Whitten and Bennett (2005) we distinguish the following functions for the Wadden Area:
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flood control; flora and fauna production; sediment accretion and deposition; ground water recharge; ground water discharge; water purification; storage of organic matter; food-chain support / cycling; water transport; tourism and recreation; and contribution to climatic stability.