Mudflats (derived from Watts ), certain coastal areas of the sea that are under a strong influence of the tides.

Large areas of the Wadden Sea fall regularly twice a day during the low water period ( low tide) dry and are flooded during the flood period ( tide). The areas falling dry at low tide is called the tidal flats. The term Wadden Sea is, however, applied only to flat coasts with sand or mud flats. Gutters, the water preferably from the Wadden runs through at low tide or preference flows at high tide in the Wadden be tidal creeks, called the largest being Seegatten.


Mudflats are found in many parts of the world in the temperate zones. In the tropical zones such coastal areas are mostly overgrown with mangroves (tidal forests ).


When the Wadden Sea floor has only a low gradient, with the height difference generally has less than a meter over a length of one kilometer. At the same time, the difference in water level between high tide and low tide is at least two meters, so that a sufficiently large area of ​​dry falls.

In the area of estuaries are fine-grained material and suspended solids that were previously flushed into rivers in relatively high rainfall, shallow areas of the country, fed by the flow of the sea. Even land-based winds cause the Wadden Sea to the material, which then becomes part of the Wadden sediment.

The Wadden Sea is divided into three zones. The subtidal area is below the mean low water level, with this also includes the tidal creeks. The supralitorale area above the mean high water level and flooded only at particularly high tides. If there is no human management are usually caused salt marshes here. The actual watts, ie, the areas that are at high water under and at low water above the water level, the eulitorale area.

Often, offshore islands and sandbanks form a protection against the breakers of the open sea and slow down the seaward ebb.

Flora and Fauna

A Wadden Sea offers a special, in parts also extreme habitat. Many animals and plants live exclusively in the respective Wadden Sea, where they are located and have adapted to the conditions prevailing there. In addition, a Wadden Sea is often an important resting area for migratory birds. In addition, the Wadden Sea provides habitat for many species of shellfish and marine worms. On higher-lying areas that fall completely dry at low water, so-called Watt benches, resting seals. At only briefly -tide ( approximately at spring tides ) surfaces to seagrasses settle, on the only intermittently flooded land plants such as samphire. There are also many unique plants, roots only on the sandy, loose soil of the coastal dunes and stabilize them.

Environmental problems

The Wadden Sea habitat is very sensitive and susceptible to external influences that are part of human origin. These include embankments and drainage supralitoraler areas of mudflats, entry of pollutants from industry, and from excessive nutrient levels through agriculture and impacts of overfishing, transport and tourism.

Therefore, there are worldwide initiatives for the protection of the Wadden Sea, which already show approaches to international cooperation. In order to better coordinate, for example, the protection of the Wadden Sea to the North Sea in 1978 by the Netherlands, Germany and Denmark, the Common Wadden Sea Secretariat ( CWSS ) or Wadden Sea Secretariat was established.

Mudflats worldwide

  • In Europe on the North Sea the Wadden Sea in the German Bight: the Hamburg Wadden Sea National Park
  • The National Park Wadden Sea
  • The National Park Schleswig -Holstein Wadden Sea
  • Staatsnatuurmonument the Waddenzee
  • The Wadden Sea at Mont -Saint -Michel with a built on a granite rock monastery in the middle of the Wadden Sea
  • On the British side in the area of the counties of Kent and East Sussex, the Romney Marsh
  • The Baie de Bourgneuf with the island of Noirmoutier (France)
  • In Africa on the North African Atlantic coast Banc - d'Arguin National Park in Mauritania
  • In North America on the Atlantic coast the Minas Basin, an arm of the Bay of Fundy (Canada), about 400 km ²
  • The Cape Cod Bay ( USA)
  • Parts of the bay from San Francisco ( USA)
  • In South America Marsh areas on both sides of the estuary of the Essequibo
  • In East Asia the Korean Yellow Sea coast; the largest contiguous Wadden area, Saemangeum ( 400 km ²), was dammed in 2006.
  • The nature reserve Chongming Dongtan in Shanghai (China)