Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are

coastal wetland 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 ...

s that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal flat ecosystems are as extensive globally as

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in sever ...

s, covering at least of the Earth's surface. / They are found in sheltered areas such as

bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a na ...

bayou In usage in the Southern United States, a bayou () is a body of water typically found in a flat, low-lying area. It may refer to an extremely slow-moving stream, river (often with a poorly defined shoreline), marshy lake, wetland, or creek. They ...

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'' ...

s, and

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 environmen ...

; they are also seen in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does inclu ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

s and salty lakes (or inland seas) alike, wherein many rivers and creeks end. Mudflats may be viewed

geologically Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...

as exposed layers of

bay mud Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glaci ...

, resulting from deposition of

estuarine 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 ...

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel whe ...

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay parti ...

s and aquatic animal

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

. Most of the sediment within a mudflat is within the

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 of ...

, and thus the flat is submerged and exposed approximately twice daily. A recent global remote sensing analysis estimated that approximately 50% of the global extent of tidal flats occurs within eight countries (

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guinea. In ...

, China, Australia,

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...

, Canada,

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, Brazil, and

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

) and that 44% of the world's tidal flats occur within Asia (). A 2022 analysis of tidal wetland losses and gains estimates that global tidal flats experienced losses of between 1999 and 2019, which were largely offset by global gains of over the same time period. In the past tidal flats were considered unhealthy, economically unimportant areas and were often dredged and developed into agricultural land. On the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...

coast of Germany in places, mudflats are exposed not by tidal action, but by wind-action driving water away from the shallows into the sea. This kind of wind-affected mudflat is called ''

Windwatt A ''Windwatt'' is a mudflat exposed as a result of wind action on water. They occur especially in the Western Pomerania Lagoon Area National Park on Germany's Baltic Sea coast. The term is German.

'' in German.

Ecology

Tidal flats, along with intertidal

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominate ...

es and

forests, are important

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

s. They usually support a large population of wildlife, and are a key habitat that allows tens of millions of migratory

shorebirds 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 ...

to migrate from breeding sites in the northern hemisphere to non-breeding areas in the southern hemisphere. They are often of vital importance to

migratory bird Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by ...

s, as well as certain species of

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estim ...

s and

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

. In the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Nor ...

mudflats have been classified as a Biodiversity Action Plan priority habitat. The maintenance of mudflats is important in preventing coastal erosion. However, mudflats worldwide are under threat from predicted

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cryo ...

s, land claims for development,

dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing da ...

due to shipping purposes, and

chemical pollution A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., with ...

. In some parts of the world, such as East and South-East Asia, mudflats have been reclaimed for

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

, and industrial development. For example, around the Yellow Sea region of East Asia, more than 65% of mudflats present in the early 1950s had been destroyed by the late 2000s. / It is estimated that up to 16% of the world tidal flats have disappeared since the mid-1980s. Mudflat sediment deposits are focused into the

which is composed of a barren zone and marshes. Within these areas are various ratios of sand and mud that make up the sedimentary layers. The associated growth of coastal sediment deposits can be attributed to rates of subsidence along with rates of deposition (example: silt transported via river) and changes in sea level. Barren zones extend from the lowest portion of the intertidal zone to the marsh areas. Beginning in close proximity to the tidal bars, sand dominated layers are prominent and become increasingly muddy throughout the tidal channels. Common bedding types include laminated sand, ripple bedding, and bay mud.

Bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a pr ...

also has a strong presence in barren zones.

Marshes A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

contain an abundance of

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

s while the sediment layers consist of thin sand and mud layers.

Mudcrack Mudcracks (also known as mud cracks, desiccation cracks or cracked mud) are sedimentary structures formed as muddy sediment dries and contracts.Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA, ...

s are a common as well as wavy bedding planes. Marshes are also the origins of coal/peat layers because of the abundant decaying plant life. Salt pans can be distinguished in that they contain thinly laminated layers of clayey silt. The main source of the silt comes from rivers. Dried up mud along with wind erosion forms silt dunes. When flooding, rain or tides come in, the dried sediment is then re-distributed. Skagit_Bay_6308

Selected example areas

Arcachon Bay Arcachon Basin or alternatively Arcachon Bay ( French: ''Bassin d'Arcachon'') is a bay of the Atlantic Ocean on the southwest coast of France, situated in Pays de Buch between the Côte d'Argent and the Côte des Landes, in the region of Aquit ...

, France *

Banc d'Arguin The Banc d'Arguin National Park ( ar, حوض أركين) of Bay of Arguin lies in Western Africa on the west coast of Mauritania between Nouakchott and Nouadhibou and is the former mouth of the Tamanrasset River. The World Heritage Site is a m ...

Mauritania Mauritania (; ar, موريتانيا, ', french: Mauritanie; Berber: ''Agawej'' or ''Cengit''; Pulaar: ''Moritani''; Wolof: ''Gànnaar''; Soninke:), officially the Islamic Republic of Mauritania ( ar, الجمهورية الإسلامي� ...

Great Rann of Kutch The Great Rann of Kutch (or Rann of Kutch seasonal salt marsh) is a salt marsh in the Thar Desert in the Kutch District of Gujarat, India. It is about 7500 km2 (2900 sq miles) in area and is reputed to be one of the largest salt de ...

* Belhaven,

East Lothian East Lothian (; sco, East Lowden; gd, Lodainn an Ear) is one of the 32 council areas of Scotland, as well as a historic county, registration county and lieutenancy area. The county was called Haddingtonshire until 1921. In 1975, the hist ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to th ...

Bridgwater Bay Bridgwater Bay is on the Bristol Channel, north of Bridgwater in Somerset, England at the mouth of the River Parrett and the end of the River Parrett Trail. It stretches from Minehead at the southwestern end of the bay to Brean Down in the n ...

and

Morecambe Bay Morecambe Bay is a large estuary in northwest England, just to the south of the Lake District National Park. It is the largest expanse of intertidal mudflats and sand in the United Kingdom, covering a total area of . In 1974, the second largest ...

Cape Cod Bay A cape is a clothing accessory or a sleeveless outer garment which drapes the wearer's back, arms, and chest, and connects at the neck. History Capes were common in medieval Europe, especially when combined with a hood in the chaperon. T ...

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

Cook Inlet Cook Inlet ( tfn, Tikahtnu; Sugpiaq: ''Cungaaciq'') stretches from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage. On its so ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

* Lindisfarne Island, England,

Minas Basin , image = Lookout On Way to Cape Split - 25006718579.jpg , alt = , caption = Looking east across the Southern Bight of Minas Basin from The Lookoff , image_bathymetry = , alt_bathymetry = , ca ...

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Engl ...

, Canada *

Moreton Bay Moreton Bay is a bay located on the eastern coast of Australia from central Brisbane, Queensland. It is one of Queensland's most important coastal resources. The waters of Moreton Bay are a popular destination for recreational anglers and are ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

, Australia *

North Slob The North Slob is an area of mud-flats at the estuary of the River Slaney at Wexford Harbour, Ireland. The North Slob is an area of that was reclaimed in the mid-19th century by the building of a sea wall.Wexford Wexford () is the county town of County Wexford, Ireland. Wexford lies on the south side of Wexford Harbour, the estuary of the River Slaney near the southeastern corner of the island of Ireland. The town is linked to Dublin by the M11/N11 Nat ...

Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...

Padilla Bay Padilla Bay is a bay located in the U.S. state of Washington, between the San Juan Islands and the mainland. Fidalgo Island and Guemes Island lie to the west of Padilla Bay. Guemes Channel, between the islands, connects Padilla Bay to Rosario St ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

Plymouth Bay Plymouth Bay is a small, well-protected bay of the Atlantic Ocean on the western shore of larger Cape Cod Bay along the coastline of the Commonwealth of Massachusetts. Plymouth Bay retains historical significance for the landing at Plymouth Rock in ...

Port of Tacoma The Port of Tacoma is an independent seaport located in Tacoma, Washington. The port was created by a vote of Pierce County citizens on November 5, 1918. The ''Edmore'' was the first ship to call at the port in 1921. The port's marine cargo oper ...

Port Susan Port Susan is a bay and strait located in the U.S. state of Washington. Part of the Whidbey Island Basin of Puget Sound, Port Susan is bounded by Camano Island to the west and the mainland to the east. The Stillaguamish River empties into the no ...

, Warm Beach,

Skagit Bay Skagit Bay is a bay and strait located in the U.S. state of Washington. It is part of the Whidbey Island Basin of Puget Sound. The Skagit River empties into Skagit Bay. To the south, Skagit Bay connects with the rest of Puget Sound via Saratoga ...

* Snettisham

Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the North ...

England,

Wadden Sea The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern conti ...

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 Neth ...

, Germany,

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 = Kingdom of Denmark , established ...

* West coast of Andros Island, Bahamas * Yellow Sea: China,

North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korea, Korean Peninsula and shares borders with China and Russia to the north, at the Yalu River, Y ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korean Peninsula and sharing a land border with North Korea. Its western border is formed by the Yellow Sea, while its ea ...

References

External links

Tidal FlatsTidal Flats Field SitesIntertidal Change Explorer
{{Authority control Landforms Wetlands Coastal geography

Ecology

Selected example areas

See also

References

External links