Wadden Sea

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Wadden Sea
UNESCO World Heritage Site
Location North Sea in Denmark, Germany and the Netherlands
Criteria Natural: viii, ix, x
Reference 1314
Inscription2009 (33rd session)

The Wadden Sea (Dutch : Waddenzee [ˈʋɑdə(n)zeː] ( Loudspeaker.svg listen ); German : Wattenmeer; Low German : Wattensee or Waddenzee; Danish : Vadehavet; West Frisian : Waadsee; North Frisian : di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of low-lying Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It has a high biological diversity and is an important area for both breeding and migrating birds. In 2009, the Dutch and German parts of the Wadden Sea were inscribed on UNESCO's World Heritage List and the Danish part was added in June 2014. [1] [2]


The Wadden Sea stretches from Den Helder, in the northwest of the Netherlands, past the great river estuaries of Germany to its northern boundary at Skallingen in Denmark along a total coastline of some 500 km (310 mi) and a total area of about 10,000 km2 (3,900 sq mi). Within the Netherlands it is bounded from the IJsselmeer by the Afsluitdijk. Historically, the coastal regions were often subjected to large floods, resulting in thousands of deaths, including the Saint Marcellus' flood of 1219, Burchardi flood of 1634 and Christmas Flood of 1717. Some of these also significantly changed the coastline. [3] [4] Numerous dikes and causeways have been built, [5] and as a result recent floods have resulted in few or no fatalities (even if some dikes rarely and locally have been overrun in recent history). [3] [4] This makes it among the most human-altered habitats on the planet. [5]


Map showing the Wadden Sea in dark blue Morze Wattowe.png
Map showing the Wadden Sea in dark blue
Salt marsh and mudflats in Westerhever, Germany Westerhever salzwiesenrest.JPG
Salt marsh and mudflats in Westerhever, Germany
The mudflats of the Pilsumer Watt near Greetsiel, Germany Pilsumer Watt from the Leyhorn 2.jpg
The mudflats of the Pilsumer Watt near Greetsiel, Germany


The word wad is Dutch for "mud flat" (Low German and German : Watt, Danish : Vade). The area is typified by extensive tidal mud flats, deeper tidal trenches (tidal creeks) and the islands that are contained within this, a region continually contested by land and sea. [6]

The landscape has been formed for a great part by storm tides in the 10th to 14th centuries, overflowing and carrying away former peat land behind the coastal dunes. The present islands are a remnant of the former coastal dunes.

Towards the North Sea the islands are marked by dunes and wide sandy beaches, and towards the Wadden Sea a low, tidal coast. The impact of waves and currents carrying away sediments is slowly changing both land masses and coastlines. For example, the islands of Vlieland and Ameland have moved eastwards through the centuries, having lost land on one side and added it on the other.


The Wadden Sea is famous for its rich flora and fauna, especially birds. Hundreds of thousands of waders, ducks, and geese use the area as a migration stopover or wintering site. It is also a rich habitat for gulls and terns, [7] as well as a few species of herons, Eurasian spoonbills and birds-of-prey, including a small and increasing breeding population of white-tailed eagles. [8] However, the biodiversity of Wadden Sea is smaller today than it once was; for birds, greater flamingos and Dalmatian pelicans used to be common as well, at least during the Holocene climatic optimum when the climate was warmer. [9] [10] Some regionally extinct species are still found here. [11] [12]

Larger fish including rays, Atlantic salmon and brown trout are still present in several sections of the Wadden Sea, but others like European sea sturgeon only survive in the region through a reintroduction project. The world's only remaining natural population of houting survives in the Danish part of the Wadden Sea and it has been used as a basis for reintroductions further south, but considerable taxonomic confusion remains over its status (whether it is the same as the houting that once lived further south in the Wadden Sea). [13] [14] European oyster once formed large beds in the region and was still present until a few decades ago, when extirpated due to a combination of disease and the continued spread of the invasive Pacific oyster, which now forms large beds in the Wadden Sea. [15] Especially the southwestern part of the Wadden Sea has been greatly reduced. Historically, the Rhine was by far the most important river flowing into this section, but it has been greatly reduced due to dams. As a result, about 90% of all the species which historically inhabited that part of the Wadden Sea are at risk. [16]

Harbor seals on Terschelling, Netherlands Phoca vitulina Terschelling.jpg
Harbor seals on Terschelling, Netherlands

Wadden Sea is an important habitat for both harbour and grey seals. Harbour porpoises and white-beaked dolphins are the sea's only resident cetaceans. They were once extinct in the southern part of the sea but have also re-colonized that area again. [17] Many other cetaceans only visit seasonally, or occasionally. [18] [19] [20] In early history, North Atlantic right whales and gray whales were present in region, perhaps using the shallow, calm waters for feeding and breeding. It has been theorized that they were hunted to extinction in this region by shore-based whalers in medieval times. [21] [22] They are generally considered long-extinct in the region, but in the Netherlands a possible right whale was observed close to beaches on Texel in the West Frisian Islands and off Steenbanken, Schouwen-Duiveland in July 2005. [23] Recent increases in number of North Atlantic humpback whales and minke whales might have resulted in more visits and possible re-colonization by the species to the areas especially around Marsdiep. [24] [25] Future recovery of once-extinct local bottlenose dolphins is also expected. [17]

Threats to the ecosystem

A number of human-introduced invasive species, including algae, plants, and smaller organisms, are causing negative effects on native species. [26]


North Frisian Islands 13-09-29-nordfriesisches-wattenmeer-RalfR-05.jpg
North Frisian Islands

Each of three countries has designated Ramsar sites in the region (see Wadden Sea National Parks).

Although the Wadden Sea is not yet listed as a transboundary Ramsar site, a great part of the Wadden Sea is protected in cooperation of all three countries. The governments of the Netherlands, Denmark and Germany have been working together since 1978 on the protection and conservation of the Wadden Sea. Co-operation covers management, monitoring and research, as well as political matters. Furthermore, in 1982, a Joint Declaration on the Protection of the Wadden Sea was agreed upon to co-ordinate activities and measures for the protection of the Wadden Sea. In 1997, a Trilateral Wadden Sea Plan was adopted. [27]

In 1986, the Wadden Sea Area was declared a biosphere reserve by UNESCO. [28]

In June 2009, the Wadden Sea (comprising the Dutch Wadden Sea Conservation Area and the German Wadden Sea National Parks of Lower Saxony and Schleswig-Holstein) was placed on the World Heritage list by UNESCO. [29] The Danish part was added to the site in 2014.


People on the beach on Borkum, Germany Borkum Strandkoerbe 20070712.jpg
People on the beach on Borkum, Germany
Mudflat hiking near Pieterburen, Netherlands Wadlopen bij Pieterburen 02a.jpg
Mudflat hiking near Pieterburen, Netherlands

Many of the islands have been popular seaside resorts since the 19th century.

Mudflat hiking, i.e., walking on the sandy flats at low tide, has become popular in the Wadden Sea. [30]

It is also a popular region for pleasure boating.


The German part of the Wadden Sea was the setting for the 1903 Erskine Childers novel The Riddle of the Sands and Else Ury's 1915 novel Nesthäkchen in the Children's Sanitorium .

Related Research Articles

North Sea marginal sea of the Atlantic Ocean

The North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of 570,000 square kilometres (220,000 sq mi).

Nordfriesland (district) District in Schleswig-Holstein, Germany

Nordfriesland is the northernmost district of Germany, part of the state of Schleswig-Holstein. It includes almost all of traditional North Frisia along with adjacent areas to the east and south and is bound by the districts of Schleswig-Flensburg and Dithmarschen, the North Sea and the Danish county of South Jutland. The district is called Kreis Nordfriesland in German, Kreis Noordfreesland in Low German, Kris Nordfraschlönj in Mooring North Frisian, Kreis Nuurdfresklun in Fering North Frisian and Nordfrislands amt in Danish.

Wadden Sea National Parks Wadden Sea national parks of the North Sea

The Wadden Sea National Parks in Denmark, Germany and the Netherlands are located along the German Bight of the North Sea. In Germany and Denmark they also mark the area of the UNESCO World Heritage Site of the Wadden Sea. Divided from each other by administrative borders, they form a single ecological entity. The purpose of the national parks is the protection of the Wadden Sea ecoregion.

Schleswig-Holstein Wadden Sea National Park national park in Germany

The Schleswig-Holstein Wadden Sea National Park is a national park in the Schleswig-Holstein area of the German Wadden Sea. It was founded by the Parliament of Schleswig-Holstein on 1 October 1985 by the National Park Act of 22 July 1985 and expanded significantly in 1999. Together with the Lower Saxon Wadden Sea National Park, the Hamburg Wadden Sea National Park and those parts of Elbe estuary which are not nature reserves, it forms the German part of the Wadden Sea.

Amrum German island

Amrumpronunciation  is one of the North Frisian Islands on the German North Sea coast, south of Sylt and west of Föhr. It is part of the Nordfriesland district in the federal state of Schleswig-Holstein and has appromixately 2,300 inhabitants.

West Frisian Islands chain of islands in the North Sea

The West Frisian Islands are a chain of islands in the North Sea off the Dutch coast, along the edge of the Wadden Sea. They continue further east as the German East Frisian Islands and are part of the Frisian Islands.

Frisian Islands archipelago in the Wadden Sea

The Frisian Islands, also known as the Wadden Islands or the Wadden Sea Islands, form an archipelago at the eastern edge of the North Sea in northwestern Europe, stretching from the northwest of the Netherlands through Germany to the west of Denmark. The islands shield the mudflat region of the Wadden Sea from the North Sea.

Rottumeroog island in the Netherlands

Rottumeroog is an uninhabited island in the Wadden Sea and is part of the Netherlands. The island is one of three West Frisian Islands in the province of Groningen. It is situated between the islands of Rottumerplaat and Borkum.

German Bight southeastern bight of the North Sea

The German Bight is the southeastern bight of the North Sea bounded by the Netherlands and Germany to the south, and Denmark and Germany to the east. To the north and west it is limited by the Dogger Bank. The Bight contains the Frisian and Danish Islands. The Wadden Sea is approximately ten to twelve kilometres wide at the location of the German Bight. The Frisian islands and the nearby coastal areas are collectively known as Frisia. The southern portion of the bight is also known as the Heligoland Bight. Between 1949 and 1956 the BBC Sea Area Forecast used "Heligoland" as the designation for the area now referred to as German Bight.

Halligen type of small island in the Wadden Sea without protective dikes

The Halligen (German) or the halliger are small islands without protective dikes. There are ten German halligen in the North Frisian Islands on Schleswig-Holstein's Wadden Sea-North Sea coast in the district of Nordfriesland and one hallig at the west coast of Denmark.

Rømø Danish island

Rømø is a Danish island in the Wadden Sea. Rømø is part of Tønder Municipality. The island has 650 inhabitants as of 1 January 2011 and covers an area of 129 km².

Spiekeroog Place in Lower Saxony, Germany

Spiekeroog is one of the East Frisian Islands, off the North Sea coast of Germany. It is situated between Langeoog to its west, and Wangerooge to its east. The island belongs to the district of Wittmund, in Lower Saxony in Germany. The only village on the island is also called Spiekeroog.The island is part of the Wadden Sea World Heritage Site by the UNESCO and the Wittbülten National Park.

Mudflat hiking

Mudflat hiking is a recreation enjoyed in the Netherlands, northwest Germany and in Denmark. Mudflat hikers are people who, with the aid of a tide table, use a period of low water to walk and wade on the watershed of the mudflats, especially from the Frisian mainland coast to the Frisian islands.

Danish Wadden Sea Islands island group

The Danish Wadden Sea Islands are a group of islands on the western coast of Jutland, Denmark. They have belonged to the region of Southern Denmark since January 1, 2007. Previously they belonged to the counties of South Jutland and Ribe.

Houting European extinct fish

The houting is a European, allegedly extinct species of whitefish in the family Salmonidae. It is native to the estuaries and rivers draining to the North Sea. The houting is distinguishable from other Coregonus taxa by having a long, pointed snout, an inferior mouth and a different number of gill rakers. The houting once occurred in Belgium, France, Germany, the Netherlands and England.

Coastline of the North Sea The North Sea is a marginal sea of ​​the Atlantic Ocean.  It is a shelf sea and is located in northwestern Europe.

The coastline of the North Sea has been evolving since the last glacier receded. The coastline varies from fjords, river estuaries to mudflats.

Wadden Sea National Park, Denmark National park in Denmark

Wadden Sea National Park was designated a Danish national park on 17 January 2008, effective 2010. Since June 2014 it has constituted the Danish part of the UNESCO's Wadden Sea World Heritage Site. Prince Joachim of Denmark is Patron of the Wadden Sea Centre.

Lower Saxon Wadden Sea National Park

The Lower Saxon Wadden Sea National Park was established in 1986 and embraces the East Frisian Islands, mudflats and salt marshes between the Bay of Dollart on the border with the Netherlands in the west and Cuxhaven as far as the Outer Elbe shipping channel in the east. The national park has an area of about 345,800 hectares (1,335 sq mi). The National Park organisation is located in Wilhelmshaven. Since June 2009 the Lower Saxon Wadden Sea National Park has become a UNESCO World Heritage Site along with the Schleswig-Holstein Wadden Sea and the Dutch Wadden Sea.

Stevns Klint cliff in Stevns Municipality, Denmark

Stevns Klint is a white chalk cliff located some 6 km (3.7 mi) southeast of Store Heddinge on the Danish island of Zealand. Stretching 17 km (11 mi) along the coast, it is of geological importance as one of the best exposed Cretaceous-Tertiary (K/T) boundaries in the world. Subject to frequent erosion, the cliff rises to a height of up to 40 m (130 ft). The cliffs are a UNESCO site.


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