The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

in the southeastern part of the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

. It lies between the coast of northwestern

continental Europe Continental Europe or mainland Europe is the contiguous continent of Europe, excluding its surrounding islands. It can also be referred to ambiguously as the European continent, – which can conversely mean the whole of Europe – and, by ...

and the range of low-lying

Frisian Islands 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 Denma ...

, forming a shallow body of water with

tidal flat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...

s and

wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

. It has a high

biological diversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') lev ...

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 The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...

World Heritage List A World Heritage Site is a landmark or area with legal protection by an international convention administered by the UNESCO, United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNES ...

and the Danish part was added in June 2014. The Wadden Sea stretches from

Den Helder Den Helder () is a municipality and a city in the Netherlands, in the province of North Holland. Den Helder occupies the northernmost point of the North Holland peninsula. It is home to the country's main naval base. From here the Royal TESO fe ...

, in the northwest of the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

, past the great river

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

to its northern boundary at Skallingen in

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...

along a total coastline of some and a total area of about . Within the Netherlands, it is bounded from the

IJsselmeer The IJsselmeer (; fy, Iselmar, nds-nl, Iesselmeer), also known as Lake IJssel in English, is a closed off inland bay in the central Netherlands bordering the provinces of Flevoland, North Holland and Friesland. It covers an area of with an a ...

by the

Afsluitdijk The ''Afsluitdijk'' (; fry, Ofslútdyk; nds-nl, Ofsluutdiek; en, "Closure Dyke") is a major dam and causeway in the Netherlands. It was constructed between 1927 and 1932 and runs from Den Oever in North Holland province to the village of ...

. Historically, the coastal regions were often subjected to large floods, resulting in thousands of deaths, including the

Saint Marcellus' flood Saint Marcellus's flood or (Low Saxon: ; da, Den Store Manddrukning, 'Great Drowning of Men') was an intense extratropical cyclone, coinciding with a new moon, which swept across the British Isles, the Netherlands, northern Germany, and Denmark ...

s of 1219 and 1362,

Burchardi flood The Burchardi flood (also known as the second Grote Mandrenke) was a storm tide that struck the North Sea coast of North Frisia and Dithmarschen (in modern-day Germany) on the night between 11 and 12 October 1634. Overrunning dikes, it shattered ...

of 1634 and Christmas Flood of 1717. Some of these also significantly changed the coastline. Numerous

dike Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes, ...

s and several

causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet Tra ...

s have been built, 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). This makes it among the most human-altered habitats on the planet.

Environment

The word ''wad'' is Frisian and Dutch for "mud flat" (

Low German : : : : : (70,000) (30,000) (8,000) , familycolor = Indo-European , fam2 = Germanic , fam3 = West Germanic , fam4 = North Sea Germanic , ancestor = Old Saxon , ancestor2 = Middle L ...

and german: Watt, da, Vade). The area is typified by extensive tidal

mud flat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...

s, deeper tidal trenches ( tidal creeks) and the islands that are contained within this, a region continually contested by land and sea. The landscape has been formed for a great part by

storm tide A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the no ...

s in the 10th to 14th centuries, overflowing and carrying away former

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

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

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

s is slowly changing both land masses and coastlines. For example, the islands of

Vlieland Vlieland (; fry, Flylân) is a Municipalities of the Netherlands, municipality and island in the northern Netherlands. The municipality of Vlieland is the second most sparsely populated municipality in the Netherlands, after Schiermonnikoog. V ...

and

Ameland Ameland (; West Frisian: It Amelân) is a municipality and one of the West Frisian Islands off the north coast of the Netherlands. It consists mostly of sand dunes. It is the third major island of the West Frisians. It neighbours islands ...

have moved eastwards through the centuries, having lost land on one side and added it on the other.

Fauna

The Wadden Sea is famous for its rich

flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. E ...

and

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoo ...

, especially birds. Hundreds of thousands of

wader 245px, A flock of Dunlins and Red knots">Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflat ...

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...

s, and

geese A goose (plural, : geese) is a bird of any of several waterfowl species in the family (biology), family Anatidae. This group comprises the genera ''Anser (bird), Anser'' (the grey geese and white geese) and ''Branta'' (the black geese). Some o ...

use the area as a

migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

stopover or wintering site. It is also a rich habitat for

gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century, m ...

s and

tern Terns are seabirds in the family Laridae that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated as a subgroup of the family Laridae which includes gulls and skimmers and consists of e ...

s, as well as a few species of

heron The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus ...

Eurasian spoonbill The Eurasian spoonbill (''Platalea leucorodia''), or common spoonbill, is a wading bird of the ibis and spoonbill family Threskiornithidae. The genus name ''Platalea'' is from Latin and means "broad", referring to the distinctive shape of the b ...

s and birds-of-prey, including a small and increasing breeding population of

white-tailed eagle The white-tailed eagle (''Haliaeetus albicilla'') is a very large species of sea eagle widely distributed across temperate Palearctic, Eurasia. Like all eagles, it is a member of the family Accipitridae (or accipitrids) which includes other diur ...

s. However, the biodiversity of Wadden Sea is smaller today than it once was; for birds,

greater flamingo The greater flamingo (''Phoenicopterus roseus'') is the most widespread and largest species of the flamingo family. It is found in Africa, the Indian subcontinent, the Middle East, and in southern Europe. Taxonomy The greater flamingo was desc ...

s and

Dalmatian pelican The Dalmatian pelican (''Pelecanus crispus'') is the largest member of the pelican family, and perhaps the world's largest freshwater bird, although rivaled in weight and length by the largest swans. They are elegant soaring birds, with wingspan ...

s used to be common as well, at least during the

Holocene climatic optimum The Holocene Climate Optimum (HCO) was a warm period that occurred in the interval roughly 9,000 to 5,000 years ago BP, with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optimu ...

when the climate was warmer. Due to human activity and a changing environment, species have gone extinct, while others are expected to migrate in. Larger fish including

rays Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

Atlantic salmon The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlantic salmon are ...

and

brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

are still present in several sections of the Wadden Sea, but others like

European sea sturgeon The European sea sturgeon (''Acipenser sturio''), also known as the Atlantic sturgeon or common sturgeon, is a species of sturgeon native to Europe. It was formerly abundant, being found in coastal habitats all over Europe. It is anadromous and b ...

only survive in the region through a reintroduction project. The world's only remaining natural population of

houting The houting (''Coregonus oxyrhynchus'') 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'' t ...

survives in the Danish part of the Wadden Sea and it has been used as a basis for reintroductions further south, but considerable

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

confusion remains over its status (whether it is the same as the houting that once lived further south in the Wadden Sea). 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 The Pacific oyster, Japanese oyster, or Miyagi oyster (''Magallana gigas''), is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand. Etymology The genus ''Mag ...

, which now forms large beds in the Wadden Sea. Especially the southwestern part of the Wadden Sea has been greatly reduced. Historically, the

Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , so ...

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. The Wadden Sea is an important habitat for both

harbour A harbor (American English), harbour (British English; see spelling differences), or haven is a sheltered body of water where ships, boats, and barges can be docked. The term ''harbor'' is often used interchangeably with ''port'', which is a ...

and

grey seal The grey seal (''Halichoerus grypus'') is found on both shores of the North Atlantic Ocean. In Latin Halichoerus grypus means "hook-nosed sea pig". It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or " ...

Harbour porpoise The harbour porpoise (''Phocoena phocoena'') is one of eight extant species of porpoise. It is one of the smallest species of cetacean. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar ...

s and

white-beaked dolphin The white-beaked dolphin (''Lagenorhynchus albirostris'') is a marine mammal belonging to the family Delphinidae (oceanic dolphins) in the suborder Odontoceti (toothed whales). Taxonomy The species was first described by the British taxonomist ...

s are the sea's only resident

cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

s. They were once extinct in the southern part of the sea but have also re-colonized that area again. Many other cetaceans only visit seasonally, or occasionally. In early history,

North Atlantic right whale The North Atlantic right whale (''Eubalaena glacialis'') is a baleen whale, one of three right whale species belonging to the genus ''Eubalaena'', all of which were formerly classified as a single species. Because of their docile nature, their ...

s and

gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bree ...

s (now extinct in the North Atlantic) 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. They are generally considered long-extinct in the region, but in the Netherlands a possible right whale was observed close to beaches on

Texel Texel (; Texels dialect: ) is a municipality and an island with a population of 13,643 in North Holland, Netherlands. It is the largest and most populated island of the West Frisian Islands in the Wadden Sea. The island is situated north of De ...

in the

West Frisian Islands The West Frisian Islands (; fry, Waadeilannen) 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. Fr ...

and off Steenbanken,

Schouwen-Duiveland Schouwen-Duiveland () is a municipality and an island in the southwestern Netherlands province of Zeeland. The municipality has 33,737 inhabitants (1 January 2016) and covers an area of (of which is water). The northside of the island has two fi ...

in July 2005. Recent increases in number of North Atlantic

humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the only species in the genus ''Megaptera''. Adults range in length from and weigh up to . The hump ...

s and

minke whale The minke whale (), or lesser rorqual, is a species complex of baleen whale. The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale. The minke whale was first described by the Danish n ...

s might have resulted in more visits and possible re-colonization by the species to the areas especially around

Marsdiep The Marsdiep is a deep tide-race between Den Helder and Texel in the Netherlands, and running southwards between sandbanks. That gap connects the North Sea and the Waddenzee. Around 1000 AD and before, much of the modern Waddenzee and IJsselmeer w ...

. Future recovery of once-extinct local

bottlenose dolphin Bottlenose dolphins are aquatic mammals in the genus ''Tursiops.'' They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus definitively contains two species: the common ...

s is also expected.

Conservation

13-09-29-nordfriesisches-wattenmeer-RalfR-05

A number of human-introduced

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

, including

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, plants, and smaller organisms, are causing negative effects on native species. Each of three countries has designated

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

Wadden Sea National Parks 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 b ...

). 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 Trilateral is something having three sides or perspectives and may refer to: *The Trilateral Ankara cooperation process, a process in Pakistani–Turkish or Afghan–Turkish relations *Trilateral Commission, a private organization, established t ...

was adopted. In 1986, the Wadden Sea Area was declared a

biosphere reserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or o ...

.UNESCO MAB Biosphere reserves directory
(last updated May 2012; retrieved 2016-07-19) 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 A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

list by

. A minor boundary modification in 2011 added the

Hamburg Wadden Sea National Park The Hamburg Wadden Sea National Park (german: Hamburgisches Wattenmeer) is the smallest of the three German Wadden Sea National Parks which protect the single ecological entity of the Wadden Sea reaching from Den Helder to Esbjerg. It is an ex ...

to the site, and the Danish part was added to in 2014.

Recreation

Many of the islands have been popular

seaside resort A seaside resort is a resort town, town, village, or hotel that serves as a Resort, vacation resort and is located on a coast. Sometimes the concept includes an aspect of official accreditation based on the satisfaction of certain requirements, suc ...

s since the 19th century.

Mudflat hiking Mudflat hiking ( da, Vadehavsvandring, nl, Wadlopen, West Frisian: ''Waadrinnen'', german: Wattwandern) is a recreation enjoyed in the Netherlands, northwest Germany, Denmark, England and France. Mudflat hikers are people who, with the aid of a ...

, i.e., walking on the sandy flats at low tide, has become popular in the Wadden Sea. It is also a popular region for pleasure boating.

Literature

The German part of the Wadden Sea was the setting for the 1903 Erskine Childers novel ''

The Riddle of the Sands ''The Riddle of the Sands: A Record of Secret Service'' is a 1903 novel by Erskine Childers. The book, which enjoyed immense popularity in the years before World War I, is an early example of the espionage novel and was extremely influentia ...

'' and

Else Ury Else Ury (1 November 1877 – 13 January 1943) was a German-Jewish novelist and children's book author. Her best-known character is the blonde doctor's daughter Annemarie Braun, whose life from childhood to old age is told in the ten volumes of th ...

's 1915 novel ''

Nesthäkchen in the Children's Sanitorium Else Ury's Nesthäkchen is a Berlin doctor's daughter, Annemarie Braun, a slim, golden blond, quintessential German girl. The ten-book :de:Nesthäkchen (Kinderbuchreihe), Nesthäkchen series follows Annemarie from infancy (''Nesthäkchen and Her ...

''.

References

External links

Wadden Sea
UNESCO Collection on Google Arts and Culture * *
Secretariat of The Trilateral Cooperation on the Protection of the Wadden Sea

Visit Vesterhavet
– tourist information for the Danish North Sea and Wadden Sea

for the westernmost part of the German National Park
The Wadden Sea
at the UNESCO World Heritage Centre
Wadden Sea World Heritage

LancewadPlan: Integrated Landscape and Cultural Heritage Management and Development Plan for the Wadden Sea Region
(A collection of studies on the cultural history of the Wadden Sea Region 2004–2007, internet archive) {{Authority control Frisian Islands Bodies of water of the North Sea World Heritage Sites in Denmark World Heritage Sites in Germany World Heritage Sites in the Netherlands Natura 2000 in the Netherlands Natura 2000 in Denmark Natura 2000 in Germany Biosphere reserves of the Netherlands Marginal seas of the Atlantic Ocean