Lagoon
![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/33/BalosLagoonCreta.jpg/220px-BalosLagoonCreta.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/23/Kara-Bogaz_Gol_from_space%2C_September_1995.jpg/220px-Kara-Bogaz_Gol_from_space%2C_September_1995.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Venice_Lagoon_December_9_2001.jpg/220px-Venice_Lagoon_December_9_2001.jpg)
Alagoonis a shallowbody of waterseparated from a larger body of water by a narrowlandform,such asreefs,barrier islands,barrier peninsulas, oristhmuses.Lagoons are commonly divided intocoastallagoons(orbarrier lagoons) andatolllagoons.They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified asestuaries.Lagoons are common coastal features around many parts of the world.
Definition and terminology
[edit]Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposedshoal,coral reef,or similar feature. Some authorities includefresh waterbodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree ofsalinity.The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restricts "lagoon" to bodies of water with little or no fresh water inflow, and little or notidalflow, and calls anybaythat receives a regular flow of fresh water an "estuary". Davis does state that the terms "lagoon" and "estuary" are "often loosely applied, even in scientific literature".[1]Timothy M. Kusky characterizes lagoons as normally being elongated parallel to the coast, while estuaries are usually drowned river valleys, elongated perpendicular to the coast.[1][2][3][4][5]Coastal lagoons are classified as inland bodies of water.[6][7]
When used within the context of a distinctive portion of coral reef ecosystems, the term "lagoon" is synonymous with the term "back reef" or "backreef", which is more commonly used by coral reef scientists to refer to the same area.[8]
Many lagoons do not include "lagoon" in their common names.Currituck,AlbemarleandPamlicoSounds inNorth Carolina,[9]Great South BaybetweenLong Islandand the barrier beaches ofFire IslandinNew York,[10]Isle of Wight Bay,which separatesOcean City, Marylandfrom the rest ofWorcester County, Maryland,[11]Banana RiverinFlorida,US,[12]Lake IllawarrainNew South Wales,Australia,[13]Montrose BasininScotland,[14]andBroad WaterinWaleshave all been classified as lagoons, despite their names. In England,The Fleetat Chesil Beach has also been described as a lagoon.
In some languages the word for a lagoon is simply a type of lake: In Chinese a lake ishu(Hồ), and a lagoon isxihu(Tả hồ). In theFrenchMediterranean several lagoons are calledétang( "lake" ). Contrariwise, several other languages have specific words for such bodies of water. In Spanish, coastal lagoons generically arelaguna costera,but those on the Mediterranean coast are specifically calledalbufera.In Russian and Ukrainian, those on theBlack Seaareliman(лиман), while the generic word islaguna(Лагуна). Similarly, in theBaltic,Danish has the specificNor,and German the specificsBoddenandHaff,as well as generic terms derived fromlaguna.In Poland these lagoons are calledzalew( "bay" ), in Lithuaniamarios( "lagoon, reservoir" ). InJutlandseveral lagoons are known asfjord.InNew ZealandtheMāoriwordhapuarefers to a coastal lagoon formed at the mouth of abraided riverwhere there are mixed sand and gravel beaches, whilewaituna,anephemeralcoastal waterbody, is neither a true lagoon, lake nor estuary.[15]
Some languages differentiate between coastal and atoll lagoons. In French,lagonrefers specifically to an atoll lagoon, while coastal lagoons are described asétang,the generic word for a still lake or pond. In Vietnamese,Đầm san hôrefers to an atoll lagoon, whilstĐầm pháis coastal.
In Latin America, the termlagunain Spanish, which lagoon translates to, may be used for a small fresh waterlakein a similar way acreekis considered a small river. However, sometimes it is popularly used to describe a full-sizedlake,such asLaguna Catemacoin Mexico, which is actually the third-largest lake by area in the country. Thebrackish waterlagoon may be thus explicitly identified as a "coastal lagoon" (laguna costera). In Portuguese, a similar usage is found:lagoamay be a body of shallow seawater, or a small freshwater lake not linked to the sea.
Etymology
[edit]Lagoon is derived from theItalianlaguna,which refers to the waters aroundVenice,theVenetian Lagoon.Lagunais attested in English by at least 1612, and had beenAnglicizedto "lagune" by 1673. In 1697William Dampierreferred to a "Lagune or Lake of Salt water" on the coast of Mexico.Captain James Cookdescribed an island "of Oval form with a Lagoon in the middle" in 1769.[16]
Atoll lagoons
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Atafutrim.jpg/220px-Atafutrim.jpg)
Atolllagoons form as coral reefs grow upwards while the islands that the reefs surround subside, until eventually only the reefs remain above sea level. Unlike the lagoons that form shoreward of fringing reefs, atoll lagoons often contain some deep (>20 m (66 ft)) portions.
Coastal lagoons
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Caspian_Sea_covered_with_plants_near_Bandar-e_Anzali_-_Barry_Kent.jpg/220px-Caspian_Sea_covered_with_plants_near_Bandar-e_Anzali_-_Barry_Kent.jpg)
Coastal lagoons form along gently sloping coasts where barrier islands or reefs can develop offshore, and the sea-level is rising relative to the land along the shore (either because of an intrinsic rise in sea-level, orsubsidenceof the land along the coast). Coastal lagoons do not form along steep or rocky coasts, or if the range of tides is more than 4 metres (13 ft). Due to the gentle slope of the coast, coastal lagoons are shallow. A relative drop in sea level may leave a lagoon largely dry, while a rise in sea level may let the sea breach or destroy barrier islands, and leave reefs too deep underwater to protect the lagoon. Coastal lagoons are young and dynamic, and may be short-lived in geological terms. Coastal lagoons are common, occurring along nearly 15 percent of the world's shorelines. In the United States, lagoons are found along more than 75 percent of theEasternandGulf Coasts.[3][4]
Coastal lagoons are usually connected to the open ocean byinletsbetween barrier islands. The number and size of the inlets, precipitation, evaporation, and inflow of fresh water all affect the nature of the lagoon. Lagoons with little or no interchange with the open ocean, little or no inflow of fresh water, and high evaporation rates, such asLake St. Lucia,inSouth Africa,may become highly saline. Lagoons with no connection to the open ocean and significant inflow of fresh water, such as theLake Worth Lagoonin Florida in the middle of the 19th century, may be entirely fresh. On the other hand, lagoons with many wide inlets, such as theWadden Sea,have strong tidal currents and mixing. Coastal lagoons tend to accumulate sediments from inflowing rivers, from runoff from the shores of the lagoon, and from sediment carried into the lagoon through inlets by the tide. Large quantities of sediment may be occasionally be deposited in a lagoon when storm waves overwash barrier islands.Mangrovesandmarshplants can facilitate the accumulation of sediment in a lagoon.Benthic organismsmay stabilize or destabilize sediments.[3][4]Lake Chilika is the largest brackish water lagoon in Asia and the second largest coastal lagoon in the world.
Largest coastal lagoons
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Lagoon | square kilometer | Country |
---|---|---|
New Caledonian lagoon | 24,000 km2(9,300 sq mi) | ![]() |
Garabogazköl | 18,000 km2(6,900 sq mi) | ![]() |
Lake Maracaibo | 13,512 km2(5,217 sq mi) | ![]() |
Lagoa dos Patos | 10,100 km2(4,000 sq mi) | ![]() |
Albemarle-Pamlicosound system | 7,800 km2(3,000 sq mi) | ![]() |
Lagos Lagoon | 6,354.7 km2(2,453.6 sq mi) | ![]() |
Curonian lagoon | 1,619 km2(625 sq mi) | ![]() ![]() |
Mayotte lagoon | ~1,500 km2(600 sq mi) | ![]() |
Rangiroa lagoon | 1,446 km2(600 sq mi) | ![]() |
Chilika Lake | 1,165 km2(450 sq mi) during monsoon season, 906 km2(350 sq mi) during dry season | ![]() |
Indian River Lagoon | 910 km2(353 sq mi)[17] | ![]() |
Vistula lagoon | 838 km2(324 sq mi) | ![]() ![]() |
Biscayne BaySystem —Biscayne Bay (traditional) |
703 km2(271 sq mi)[18] 572 km2(221 sq mi)[19] |
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Marovo lagoon | 700 km2(270 sq mi) | ![]() |
Szczecin Lagoon | 689 km2(266 sq mi) | ![]() ![]() |
Venetian lagoon | 550 km2(210 sq mi) | ![]() |
Regulation
[edit]In theEuropean Union,coastal lagoon habitat is classified and under Directive 92/43/EEC on the conservation of natural habitats and wild flora and fauna (Habitats Directive). Furthermore, numerous bird species breed in coastal lagoons. As a result, many lagoons are also protected under Directive 2009/147/EC on the conservation of birds (Birds Directive).
Images
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Aerial view ofBora BorainFrench Polynesia.
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Aerial view ofKivalina, Alaskafrom the northwest.
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Nearly half the area ofKiritimatiis covered with lagoons, some freshwater and some seawater.
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Panoramic view of Lefkada City Lagoon, Lefkada Isl.,Ionian IslandsPrefecture,Greece.
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Panoramic view of Prokopos Lagoon,Achaia,Western Greece Prefecture, Greece.
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Tropical lagoon in Bacuit Bay, Palawan, Philippines.
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Photo ofMar Menoras seen from International Space Station.
See also
[edit]References
[edit]- ^abDavis, Richard A. Jr. (1994).The Evolving Coast.New York: Scientific American Library. pp.101, 107.ISBN978-0-7167-5042-0.
- ^Allaby, Michael, ed. (1990). "Lagoon".Oxford Dictionary of Earth Sciences.Oxford: Oxford University Press.ISBN978-0-19-921194-4.
- ^abcKusky, Timothy, ed. (2005)."Lagoon".Encyclopedia of Earth Sciences.New York: Facts on File. p.245.ISBN0-8160-4973-4.
- ^abcNybakken, James W., ed. (2003). "Lagoon".Interdisciplinary Encyclopedia of Marine Sciences.Vol. 2 G-O. Danbury, Connecticut: Grolier Academic Reference. pp. 189–90.ISBN0-7172-5946-3.
- ^Reid, George K. (1961).Ecology of Inland Waters and Estuaries.New York: Van Nostrand Reinhold Company. p.74.ASINB003MRW6AK.
- ^Maurice L. Schwartz (2005).Encyclopedia of coastal science.Springer. p. 263.ISBN978-1-4020-1903-6.Retrieved31 March2012.
- ^Kjerfve, Björn (1994). "Coastal Lagoons".Coastal lagoon processes.Elsevier. pp. 1–3.ISBN978-0-444-88258-5.
- ^Aronson, R. B. (1993). "Hurricane effects on backreef echinoderms of the Caribbean".Coral Reefs.12(3–4): 139–142.Bibcode:1993CorRe..12..139A.doi:10.1007/BF00334473.S2CID879073.
- ^Jia, Peng and Ming Li (2012)."Circulation dynamics and salt balance in a lagoonal estuary".Journal of Geophysical Research: Oceans.117(C01003): C01003.Bibcode:2012JGRC..117.1003J.doi:10.1029/2011JC007124.Archived fromthe originalon Aug 19, 2014.Retrieved24 March2012.
- ^Goodbred, S. Jr., P. Locicero, V. Bonvento, S. Kolbe, S. Holsinger."History of the Great South Bay estuary:Evidence of a catastrophic origin".State University of New York.Retrieved24 March2012.
{{cite web}}
:CS1 maint: multiple names: authors list (link) - ^Boynton, W. R., J. D. Hagy, L. Murray, C. Stokes, W. M Kemp (June 1996)."A Comparative Analysis of Eutrophication Patterns in a Temperate Coastal Lagoon"(PDF).Estuaries.19(2B): 408–421.doi:10.2307/1352459.JSTOR1352459.S2CID14978943.Retrieved24 March2012.
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:CS1 maint: multiple names: authors list (link) - ^"Total Maximum Daily Loads for the North and Central Indian River Lagoon and Banana river Lagoon, Florida"(PDF).United States Environmental Protection Agency. Archived fromthe original(PDF)on 24 September 2015.Retrieved24 March2012.
- ^"Proposed Swimming Enclosure Net, Entrance Lagoon, Lake Illawarra"(PDF).Lake Illawarra Authority. Archived fromthe original(PDF)on 28 February 2011.Retrieved24 March2012.
- ^Bird, Eric C. F. (2010).Encyclopedia of the World's Coastal Landforms.Vol. 1. Dordrecht: Springer. p. 485.ISBN978-1-4020-8638-0.
- ^Kirk, R.M. and Lauder, G.A (2000).Significant coastal lagoon systems in the South Island, New Zealand: coastal processes and lagoon mouth closure.Wellington, N.Z.:Department of Conservation.ISBN0-478-21947-4.
{{cite book}}
:CS1 maint: multiple names: authors list (link) - ^"Lagoon".Oxford English Dictionary.Vol. I A-O (Compact ed.). Oxford, England: Oxford University Press. 1971. p. 1560.
- ^"Fast facts about the Indian River Lagoon".St. Johns River Water Management District.2024.Retrieved12 July2024.
- ^Smith, Ned P. (Summer 2001). "Tides of Biscayne Bay, Card Sound, Little Card Sound, Barnes Sound, and Manatee Bay, Florida".Florida Scientist.64:224.JSTOR24321024.
- ^Milano, Gary R. (2000). "Introduction".Island Restoration and Enhancement in Biscayne Bay, Florida(PDF).Miami-Dade Department of Environmental Resources Management(Report).RetrievedApril 21,2021.
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