Editing Brackish water

{{Short description|Water with salinity between freshwater and seawater}}
{{Redirect|Brackish|the Kittie song|Spit (album)}}
{{Water salinity}}
'''Brackish water''', sometimes termed '''brack water''',<ref>{{cite web | title=What is brackish water and what effect does a high concentration of ammonia have? | website=The Laboratory People | date=15 June 2012 | url=https://camblab.info/what-is-brackish-water-and-what-effect-does-a-high-concentration-of-ammonia-have/ | access-date=21 November 2020}}</ref><ref>{{cite journal | last1=Klaassen | first1=K. | last2=Bormann | first2=H. | last3=Klenke | first3=T. | last4=Liebezeit | first4=G. | title=The impact of hydrodynamics and texture on the infiltration of rain and marine waters into sand bank island sediments — Aspects of infiltration and groundwater dynamics | journal=Senckenbergiana Maritima | publisher=Springer Science and Business Media LLC | volume=38 | issue=2 | year=2008 | issn=0080-889X | doi=10.1007/bf03055293 | pages=163–171| s2cid=6229273 }}</ref> is water occurring in a natural environment that has more [[salinity]] than [[freshwater]], but not as much as [[seawater]]. It may result from mixing seawater (salt water) and fresh water together, as in [[estuary|estuaries]], or it may occur in brackish [[Fossil water|fossil aquifers]]. The word comes from the Middle Dutch root ''[[:wikt:brak#Dutch|brak]]''. Certain human activities can produce brackish water, in particular [[civil engineering]] projects such as dikes and the flooding of coastal [[marsh]]land to produce brackish water pools for [[freshwater prawn farming]]. Brackish water is also the primary waste product of the [[Osmotic power|salinity gradient power]] process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it can be damaging to the environment (see article on [[shrimp farming|shrimp farms]]).

Technically, brackish water contains between 0.5 and 30&nbsp;grams of [[salt]] per litre—more often expressed as 0.5 to 30 [[parts per thousand]] (‰), which is a [[specific gravity]] of between 1.0004 and 1.0226. Thus, ''brackish'' covers a range of [[Salinity#Systems of classification of water bodies based upon salinity|salinity regimes]] and is not considered a precisely defined condition. It is characteristic of many brackish surface waters that their salinity can vary considerably over space or time. Water with a salt concentration greater than 30‰ is considered [[Saline water|saline]]. 
== Brackish water habitats ==

=== Estuaries ===
[[File:Monodactylus argenteus.JPG|thumb|A brackish water fish: ''[[Silver moony|Monodactylus argenteus]]'']]
Brackish water condition commonly occurs when fresh water meets seawater. In fact, the most extensive brackish water habitats worldwide are [[estuary|estuaries]], where a river meets the sea.

The [[River Thames]] flowing through [[London]] is a classic river estuary. The town of [[Teddington]] a few miles west of London marks the boundary between the [[tide|tidal]] and non-tidal parts of the Thames, although it is still considered a freshwater river about as far east as [[Battersea]] insofar as the average salinity is very low and the fish fauna consists predominantly of freshwater species such as [[Rutilus|roach]], [[Common dace|dace]], [[carp]], [[perch]], and [[pike (fish)|pike]]. The [[Thames Estuary]] becomes brackish between Battersea and [[Gravesend]], and the diversity of freshwater fish species present is smaller, primarily roach and dace; [[euryhaline]] marine species such as [[flounder]], [[European seabass]], [[mullet (fish)|mullet]], and [[Smelt (fish)|smelt]] become much more common. Further east, the salinity increases and the freshwater fish species are completely replaced by euryhaline marine ones, until the river reaches Gravesend, at which point conditions become fully marine and the fish fauna resembles that of the adjacent [[North Sea]] and includes both euryhaline and [[stenohaline]] marine species. A similar pattern of replacement can be observed with the aquatic plants and invertebrates living in the river.<ref>[http://www.the-river-thames.co.uk/thames.htm The River Thames – its geology, geography and vital statistics from source to sea] {{webarchive|url=https://web.archive.org/web/20100516000937/http://www.the-river-thames.co.uk/thames.htm |date=2010-05-16 }}, The-River-Thames.co.uk</ref><ref>[http://www.the-river-thames.co.uk/wildlife.htm The River Thames – its natural history] {{webarchive|url=https://web.archive.org/web/20060818220921/http://www.the-river-thames.co.uk/wildlife.htm |date=2006-08-18 }} The-River-Thames.co.uk</ref>

This type of [[ecological succession]] from freshwater to marine [[ecosystem]] is typical of river estuaries. River estuaries form important staging points during the migration of [[Fish migration|anadromous and catadromous]] fish species, such as [[salmon]], [[American shad|shad]] and [[eel]]s, giving them time to form social groups and to adjust to the changes in salinity. Salmon are anadromous, meaning they live in the sea but ascend rivers to spawn; eels are catadromous, living in rivers and streams, but returning to the sea to breed. Besides the species that migrate through estuaries, there are many other fish that use them as "nursery grounds" for spawning or as places young fish can feed and grow before moving elsewhere. [[Herring]] and [[plaice]] are two commercially important species that use the Thames Estuary for this purpose.

Estuaries are also commonly used as fishing grounds and as places for fish farming or ranching.<ref>{{cite web |url=http://www.eattilapia.com/tilapia-farming.php |title= Tropical Aquaculture|website=www.eattilapia.com |url-status=usurped |archive-url=https://web.archive.org/web/20100929170847/http://www.eattilapia.com/tilapia-farming.php |archive-date=September 29, 2010}}</ref>  For example, [[Atlantic salmon]] farms are often located in estuaries, although this has caused controversy, because in doing so, fish farmers expose migrating wild fish to large numbers of external [[parasitism|parasites]] such as [[sea lice]] that escape from the pens the farmed fish are kept in.<ref>{{cite web|url=http://www.saveourseatrout.com/|title=脱毛の口コミまとめ|work=saveourseatrout.com|url-status=live|archive-url=https://web.archive.org/web/20060717032912/http://www.saveourseatrout.com/|archive-date=2006-07-17}}</ref>

=== Mangroves ===
{{main|Mangrove}}
Another important brackish water habitat is the [[mangrove swamp]] or '''mangal'''. Many, though not all, mangrove swamps fringe estuaries and lagoons where the salinity changes with each tide. Among the most specialised residents of mangrove forests are [[mudskippers]], fish that forage for food on land, and [[archerfish]], perch-like fish that "spit" at insects and other small animals living in the trees, knocking them into the water where they can be eaten. Like estuaries, mangrove swamps are extremely important breeding grounds for many fish, with species such as [[Lutjanidae|snappers]], [[halfbeak]]s, and [[tarpon]] spawning or maturing among them. Besides fish, numerous other animals use mangroves, including such species as the  [[saltwater crocodile]], [[American crocodile]], [[proboscis monkey]], [[diamondback terrapin]], and the [[crab-eating frog]], ''Fejervarya cancrivora'' (formerly ''Rana cancrivora''). Mangroves represent important nesting sites for numerous birds groups such as herons, storks, spoonbills, ibises, kingfishers, shorebirds and seabirds.

Although often plagued with [[mosquito]]es and other insects that make them unpleasant for humans, mangrove swamps are very important buffer zones between land and sea, and are a natural defense against hurricane and tsunami damage in particular.<ref>[http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=1823&language=1 Mangrove forests 'can reduce impact of tsunamis'] {{webarchive|url=https://web.archive.org/web/20060618043027/http://www.scidev.net/News/index.cfm?fuseaction=readnews&itemid=1823&language=1 |date=2006-06-18 }}, Science and Development Network, December 30, 2004</ref>

The [[Sundarbans]] and [[Bhitarkanika Mangroves]] are two of the large mangrove forests in the world, both on the coast of the [[Bay of Bengal]].

=== Brackish seas and lakes ===
{{See also|Salt lake}}
Some seas and lakes are brackish. The [[Baltic Sea]] is a brackish sea adjoining the [[North Sea]]. Originally the [[Eridanos (geology)|Eridanos]] river system prior to the [[Pleistocene]], since then it has been flooded by the North Sea but still receives so much freshwater from the adjacent lands that the water is brackish. As [[seawater]] is denser, the water in the Baltic is stratified, with seawater at the bottom and freshwater at the top. Limited mixing occurs because of the lack of tides and storms, with the result that the fish fauna at the surface is freshwater in composition while that lower down is more marine. [[Cod]] are an example of a species only found in deep water in the Baltic, while [[Northern pike|pike]] are confined to the less saline surface waters.

The [[Caspian Sea]] is the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater. The Caspian is famous for its peculiar animal fauna, including one of the few non-marine seals (the [[Caspian seal]]) and the great [[sturgeon]]s, a major source of [[caviar]].

[[Hudson Bay]] is a brackish [[marginal sea]] of the [[Arctic Ocean]], it remains brackish due its limited connections to the open ocean, very high levels freshwater [[surface runoff]] input from the large [[Hudson Bay drainage basin]], and low rate of evaporation due to being completely covered in ice for over half the year.

In the [[Black Sea]] the surface water is brackish with an average salinity of about 17–18 parts per thousand compared to 30 to 40 for the oceans.<ref name="Lüning 1991 p.121">{{cite book |last=Lüning |first=Klaus |title=Seaweeds: Their Environment, Biogeography, and Ecophysiology |publisher=John Wiley & Sons |date=1991-01-16 |isbn=978-0-471-62434-9 |ol=7619451M |page=121}}</ref> The deep, [[anoxic event|anoxic]] water of the Black Sea originates from warm, salty water of the [[Mediterranean]].

[[Lake Texoma]], a reservoir on the border between the U.S. states of [[Texas]] and [[Oklahoma]], is a rare example of a brackish lake that is neither part of an [[endorheic basin]] nor a direct arm of the ocean, though its salinity is considerably lower than that of the other bodies of water mentioned here. The reservoir was created by the damming of the [[Red River of the South]], which (along with several of its tributaries) receives large amounts of salt from natural seepage from buried deposits in the upstream region. The salinity is high enough that [[striped bass]], a fish normally found only in salt water, has self-sustaining populations in the lake.<ref>Malewitz, Jim (21 November 2013).  [https://www.texastribune.org/2013/11/21/along-salty-red-river-communities-seek-feds-help/ "Communities Along Red River Seek Feds' Help."] ''The Texas Tribune''. Retrieved 25 December 2018.</ref><ref>[https://pubs.usgs.gov/fs/fs-170-97/FS_170-97.htm U.S. Geological Survey Fact Sheet 170-97]. Retrieved 25 December 2018.</ref>

=== Brackish marsh ===
{{Main|Brackish marsh}}

=== Other brackish bodies of water===
* {{annotated link|Anchialine pool}}

== Human uses ==
Brackish water is being used by humans in many different sectors. It is commonly used as cooling water for power generation and in a variety of ways in the mining, oil, and gas industries. Once [[Desalination|desalinated]] it can also be used for agriculture, livestock, and municipal uses.<ref>{{Cite web |last=Program |first=USGS - U.S. Geological Survey Water Availability and Use Science |title=How is Brackish Groundwater Being Used? - USGS National Brackish Groundwater Assessment |url=https://water.usgs.gov/ogw/gwrp/brackishgw/use.html |access-date=2022-03-08 |website=water.usgs.gov |language=en}}</ref> Brackish water can be treated using [[reverse osmosis]], [[electrodialysis]], and other filtration processes.<ref>{{Citation |last1=Ahdab |first1=Yvana D. |title=Desalination of brackish groundwater to improve water quality and water supply |date=2020 |url=https://dspace.mit.edu/handle/1721.1/126566 |work=Prof. Lienhard |publisher=Elsevier |language=en |isbn=978-0-12-818172-0 |access-date=2022-03-08 |last2=Lienhard |first2=John H.|hdl=1721.1/126566 }}</ref>

== See also ==
* [[List of brackish bodies of water]]
* {{annotated link|Biosalinity}}
* {{annotated link|Brackish-water aquarium}}
* {{annotated link|Desalination}}
* {{annotated link|Halocline}}

== References ==
{{Reflist}}

== Further reading ==
* [https://doi.org/10.1007%2Fs10452-005-6041-y Moustakas, A. & I. Karakassis. How diverse is aquatic biodiversity research?, Aquatic Ecology, '''39''', 367-375]

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[[Category:Liquid water]]
[[Category:Aquatic ecology]]
[[Category:Coastal geography]]
[[Category:Brackish water organisms|*]]