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

coastal wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor (anoxic) processes taking place, especially in ...

s that form in intertidal areas where sediments have been deposited by

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s or

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s. 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 mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

s, covering at least of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

'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, ci ...

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'') an ...

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 environm ...

; 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. The term excludes seawater and brackish water, but it does include non-salty mi ...

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

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 the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

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 estuary, estuaries, which are normally in temperate regions that have experienced cyclic ...

, 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 environm ...

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 (chemistry), suspension with water. Silt usually ...

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

s and aquatic animal

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

. Most of the sediment within a mudflat is within the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

, and thus the flat is submerged and exposed approximately twice daily. A recent global

remote sensing Remote sensing is the acquisition of information about an physical object, object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring inform ...

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 Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, and

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

) 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. Some mudflats can be extremely treacherous to walk on. For example, the mudflats surrounding

Anchorage, Alaska Anchorage, officially the Municipality of Anchorage, is the List of cities in Alaska, most populous city in the U.S. state of Alaska. With a population of 291,247 at the 2020 United States census, 2020 census, it contains nearly 40 percent of ...

, are made from fine glacial-silt which does not easily separate out its water, and, although seemingly solid, can quickly gel and become like

quicksand Quicksand (also known as sinking sand) is a colloid consisting of fine granular material (such as sand, silt or clay) and water. It forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it crea ...

when disturbed by stepping on it. Four people are known to have become stuck up to their waists and drowned when the tide came in, and many others are rescued from the Anchorage mudflats each year. On the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

coast of

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

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'' in German.

Ecology

Tidal flats, along with intertidal

salt marsh A salt marsh, saltmarsh or salting, 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. I ...

es and

forests, are important

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

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

shorebirds FIle:Vadare - Ystad-2021.jpg, 245px, A flock of Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflats in order to foraging, forage for food c ...

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 a seasonal movement of birds between breeding and wintering grounds that occurs twice a year. It is typically from north to south or from south to north. Migration is inherently risky, due to predation and mortality. Th ...

s, as well as certain species of

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s and

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

. 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 Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

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 The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...

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 d ...

due to shipping purposes, and chemical pollution. 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. Nelu ...

agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

, and industrial development. For example, around the

Yellow Sea The Yellow Sea, also known as the North Sea, is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. Names It is one of four ...

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 ...

also has a strong presence in barren zones.

Marshes In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in general ...

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 o ...

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. File:ISS013-E-75163 - View of Tunisia.jpg, alt=Satellite view of the Kneiss Islands, Tunisia, Satellite view of the Kneiss Islands,

Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

. File:Skagit_Bay_6308.JPG, Gulls feeding on mudflats in

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 Sara ...

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

Image:brewster mudflat.jpg, Mudflats in in

Brewster, Massachusetts Brewster is a New England town, town in Barnstable County, Massachusetts, United States, Barnstable County being coextensive with Cape Cod. The population of Brewster was 10,318 at the 2020 census. Initially settled in 1659, the Town of Brewster ...

, extending hundreds of yards offshore at the low tide. The line of

Wrack (seaweed) Wrack is part of the common names of several species of seaweed in the family Fucaceae. It may also refer more generally to any seaweeds or seagrasses that wash up on beaches and may accumulate in the wrack zone. It consists largely of spec ...

and seashells in the foreground indicates the high-water mark.

Selected example areas

Arcachon Bay Arcachon Basin or alternatively Arcachon Bay (, ; ) 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 Aquitaine. The bay covers an ar ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

* Banc d'Arguin,

Mauritania Mauritania, officially the Islamic Republic of Mauritania, is a sovereign country in Maghreb, Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to Mauritania–Western Sahara border, the north and northwest, ...

* Chamiza Wetland,

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Great Rann of Kutch The Great Rann of Kutch 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 deserts in the world. This area has been ...

* Belhaven,

East Lothian East Lothian (; ; ) is one of the 32 council areas of Scotland, as well as a Counties of Scotland, historic county, registration county and Lieutenancy areas of Scotland, lieutenancy area. The county was called Haddingtonshire until 1921. In ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

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 ...

and

Morecambe Bay Morecambe Bay is an estuary in north-west 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 ga ...

Cape Cod Bay Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south ...

Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...

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

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

* Lindisfarne Island,

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

Minas Basin The Minas Basin () is an inlet of the Bay of Fundy and a sub-basin of the Fundy Basin located in Nova Scotia, Canada. It is known for its extremely high tides. Geography The Minas Basin forms the eastern part of the Bay of Fundy which splits ...

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

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 Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

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 ( ; archaic Yola dialect, Yola: ''Weiseforthe'') is the county town of County Wexford, Republic of Ireland, Ireland. Wexford lies on the south side of Wexford Harbour, the estuary of the River Slaney near the southeastern corner of the ...

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

* Kneiss Archipelago,

Padilla Bay Padilla Bay is a bay located in the U.S. state of Washington (state), 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 Padil ...

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 ...

Port of Tacoma The Port of Tacoma is an independent seaport 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 operations, am ...

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 n ...

Warm Beach Warm Beach () is a census-designated place (CDP) in Snohomish County, Washington, United States. The population was 2,990 at the 2020 census. History What is now Warm Beach was the site of a village of the Stillaguamish and Snohomish peoples ...

Snettisham Snettisham is a village and civil parish in the English county of Norfolk. It is located near the west coast of Norfolk, some south of the seaside resort of Hunstanton, north of the town of King's Lynn and northwest of the city of Norwich ...

Norfolk Norfolk ( ) is a Ceremonial counties of England, ceremonial county in England, located in East Anglia and officially part of the East of England region. It borders Lincolnshire and The Wash to the north-west, the North Sea to the north and eas ...

Wadden Sea The Wadden Sea ( ; ; or ; ; ; ) 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 tida ...

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

* West coast of Andros Island, Bahamas *

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 borders China and Russia to the north at the Yalu River, Yalu (Amnok) an ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

(

Getbol Getbol () are mudflats, or tidal flats, coastal sedimentary systems. They are important habitats for different types of organisms, including migrating birds and marine fauna such as clams, crabs, octopuses, and snails. In 2021, four getbol sites ...

)

References

External links

Tidal FlatsTidal Flats Field SitesIntertidal Change Explorer
{{Authority control Mudflats

Ecology

Selected example areas

See also

References

External links