Brackish water , sometimes termed brack water , 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 estuaries , or it may occur in brackish fossil aquifers . The word comes from the Middle Dutch root brak . Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming . Brackish water is also the primary waste product of the 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 farms ).
28-480: The Chilean mussel or Chilean blue mussel , Mytilus chilensis , is a species of blue mussel native to the coasts of Chile from Biobío Region (37 ºS) to Cape Horn (55 ºS). Genomic evidence has confirmed that the native Chilean blue mussel is genetically distinct from the Northern Hemisphere M. edulis , M. galloprovincialis and M. trossulus and also genetically different from Mytilus platensis ,
56-472: A few miles west of London marks the boundary between the 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 roach , dace , carp , perch , and pike . The Thames Estuary becomes brackish between Battersea and Gravesend , and
84-610: A natural defense against hurricane and tsunami damage in particular. The Sundarbans and Bhitarkanika Mangroves are two of the large mangrove forests in the world, both on the coast of the Bay of Bengal . Some seas and lakes are brackish. The Baltic Sea is a brackish sea adjoining the North Sea . Originally the Eridanos river system prior to the Pleistocene , since then it has been flooded by
112-459: A salt concentration greater than 30‰ is considered saline . See the salinity table from the Misplaced Pages salinity article . Brackish water condition commonly occurs when fresh water meets seawater. In fact, the most extensive brackish water habitats worldwide are estuaries , where a river meets the sea. The River Thames flowing through London is a classic river estuary. The town of Teddington
140-526: A species only found in deep water in the Baltic, while 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 sturgeons , a major source of caviar . Hudson Bay
168-861: A valid taxon in the Mytilus genus and different from Mytilus platensis . Mytilus chilensis is part of the worldwide Mytilus edulis complex of mussels, or blue mussels . Modern genetic studies based on single-nucleotide polymorphism (SNP) have demonstrated that the Chilean mussel is genetically different of both the Mediterranean mussel ( Mytilus galloprovincialis ) and the North Atlantic Mytilus edulis . Evidence collected until 2021 recognized several blue mussel species in South America, including native M. platensis , introduced M. galloprovincialis from
196-442: Is a cosmopolitan genus of medium to large-sized edible, mainly saltwater mussels , marine bivalve molluscs in the family Mytilidae . Mussels have a gray to blue-purple, fully grown shell about 5 - 10 centimeters long with an elongated oval shape. They follow the general blueprint of the mussels. They consist of a right and left half of the shell, which are held together with an elastic lock strap (ligament). The shell
224-519: Is a stub . You can help Misplaced Pages by expanding it . Brackish water Technically, brackish water contains between 0.5 and 30 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 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
252-544: 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
280-401: Is made up of 3 layers: the top layer of organic material (periostracum), the middle thick layer of lime (ostracum) and the innermost, valuable, silver-white shiny mother-of-pearl layer (hypostracum). In the shell of the mussel there are two gills with gill leaves that are well supplied with blood. Between the gills is a muscular foot with the byssus gland. With the help of the protein contained in
308-672: 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 archer fish , 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 snappers , halfbeaks , and tarpon spawning or maturing among them. Besides fish, numerous other animals use mangroves, including such species as
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#1732855213731336-504: 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 mosquitoes and other insects that make them unpleasant for humans, mangrove swamps are very important buffer zones between land and sea, and are
364-476: The brackish water from estuaries and mud flats in the coastal regions. Mytilus mussels are widely exploited as food and used in mariculture . For instance, in California, they have been consumed by coastal Native American people for almost 12 000 years. Antimicrobial peptides called Mytilin A and B have been isolated from M. galloprovincialis and M. edulis . This Mytilidae -related article
392-671: The EU, primarily Spain and France, and 15% to the United States. Alcide d'Orbigny first described the species Mytilus platensis d'Orbigny, 1842,. Species that was for many year erroneously confused with Mytilus chilensis described by Hipolito Hupé in 1854. Nowadays most biodiversity databases, such as the World Register of Marine Species or the Integrated Taxonomic Information System recognise Mytilus chilensis as
420-530: The Mediterranean, and possibly-introduced M. planulatus . Using nuclear DNA markers, Borsa et al. (2012) confirmed earlier results from allozymes that most populations in the south of the South American continent indeed represent a native Southern Hemisphere lineage of the blue mussel, for which they suggested to use the subspecies name Mytilus edulis platensis (now M. platensis ). The same authors questioned
448-479: 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
476-520: The Thames Estuary for this purpose. Estuaries are also commonly used as fishing grounds and as places for fish farming or ranching. 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 parasites such as sea lice that escape from the pens the farmed fish are kept in. Another important brackish water habitat
504-455: 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
532-406: The diversity of freshwater fish species present is smaller, primarily roach and dace; euryhaline marine species such as flounder , European seabass , mullet , and 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
560-649: The earlier identifications of the Montevideo mussel in Southern Chile as " M. galloprovincialis " because the genetic markers then used could not help distinguishing M. galloprovincialis from any of the two native blue mussel species from the Southern Hemisphere, now referred to as M. planulatus and M. platensis . Moreover, M. platensis populations in southern Chile show slight introgression from M. planulatus . Mytilus (bivalve) See text Mytilus
588-548: 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. 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 anadromous and catadromous fish species, such as salmon , shad and eels , giving them time to form social groups and to adjust to
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#1732855213731616-627: The mussel and from there to the stomach and intestines, where the food is ultimately digested. The indigestible residues are expelled from the outflow opening with the respiratory water. Each spring and summer, the females lay five to ten million eggs, which are then fertilized by the males. The fertilized egg cells become trochophoral larvae, 99.9 percent of which are eaten in the course of their four-week development into young mussels. Nevertheless, after this "selection" there are still around 10,000 young mussels left. These are about three millimeters in size and often drift around several hundred kilometers in
644-421: The mussel and iron filtered from the sea, this gland produces the byssus threads with which the mussel can hold on. Mussels have a sphincter, which is located in the soft tissue of the mussel, as well as other organs (heart, stomach, intestines, kidneys). With the help of the sphincter muscle, the mussel can close in danger or dryness. Species within the genus Mytilus include: Numerous fossil species are known,
672-482: The oceans. The deep, 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
700-453: The oldest dating to the Triassic. Mussels are filter feeders. They have two openings. The water enters the mantle cavity through the inflow opening, in which a permanent flow of water is generated by the eyelashes. The tiny food particles (plant and animal plankton) stick to the mucous layer of the gills. Then the eyelash hairs convey the mucus in the gills with the food particles to the mouth of
728-492: The other species of smooth shelled mussel from South America. Right and left valve of the same specimen: M. chilensis is under intensive aquaculture in Chile. From 2004 to 2008 the annual commercial harvest increased from 80,000 to 200,000 tonnes. Following a decrease in 2009, the production was back at high level in 2010. Over 45,000 tonnes of mussels were exported from Chile in 2008, 93% of them frozen. Some 74% of exports are to
756-427: The sea before they are about five centimeters in size in coastal regions with their byssus threads. The reason mussels live in such large colonies (also called banks) is because it gives the males a much greater chance of fertilizing eggs. After the larvae have developed freely floating as plankton for about four weeks, they attach themselves to stones, stakes, shill, sand and other mussels with byssus threads. They prefer
784-510: 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. Brackish water is being used by humans in many different sectors. It
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