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82-709: The Río de la Plata ( Spanish pronunciation: [ˈri.o ðe la ˈplata] ; lit.   ' River of Silver ' ), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda . It empties into the Atlantic Ocean and forms a funnel-shaped indentation on the southeastern coastline of South America . Depending on

164-462: A tidal prism important enough to dominate the flow regime despite the huge discharge received from the tributary rivers. The river is a salt wedge estuary in which saltwater, being denser than freshwater, penetrates into the estuary in a layer below the freshwater, which floats on the surface. Salinity fronts, or haloclines , form at the bottom and on the surface, where fresh and brackish waters meet. The salinity fronts are also pycnoclines due to

246-505: A generally southwestern direction for about 619 km (385 mi) before encountering the city of Saltos del Guaira , Paraguay. This was once the location of the Guaíra Falls (Sete Quedas waterfalls, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world-famous Iguazu Falls to the south. The falls were flooded, however, by the construction of

328-537: A gradual turn to the west for another 820 km (510 mi), and then encounters the Paraguay River , the largest tributary along the course of the river. Before this confluence, the river passes through a second major hydroelectric project, the Yacyretá Dam , a joint project between Paraguay and Argentina. The massive reservoir formed by the project has been the source of a number of problems for people living along

410-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

492-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

574-785: A slow turn back to the east near the city of Rosario for the final stretch of less than 500 km (310 mi) before merging with the Uruguay River to form the Río de la Plata . This flows into the Atlantic Ocean . During the part of its course downstream from the city of Diamante, Entre Ríos , it splits into several arms and it forms the Paraná Delta . The main tributaries from the mouth: tributary tributary (km) (km ) (m /s) Tiestos Grandes de las Conchas Garupá Guazú Piray Guazú Piray Mini Guazú Urugua-i Francisco Falço Braço Sul Francisco Verdadeiro Guaçu (Arantes) Period: 1971–2000 Together with its tributaries,

656-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

738-550: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

820-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

902-470: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

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984-463: Is "an immense number of river names containing the element para- or parana- ", from Guarani language words meaning "river" or "sea"; attempts to derive a more precise meaning for the name of this, the largest of them, e.g. "kin of the sea", have been discounted. The course is formed at the confluence of the Paranaiba and Rio Grande rivers in southern Brazil. From the confluence the river flows in

1066-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

1148-541: 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 environments and are an example of an ecotone . Estuaries are subject both to marine influences such as tides , waves , and the influx of saline water , and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in

1230-466: Is about 180 kilometres (110 mi) long and up to 80 kilometres (50 mi) wide, with a depth which varies from about 1 to 5 metres (3.3 to 16.4 ft); the depth of the outer estuary zone increases from 5 to 25 metres (16 to 82 ft). The river's discharge is strong enough to prevent saltwater from penetrating to the inner portion. The Río de la Plata behaves as an estuary in which freshwater and seawater mix. The freshwater comes principally from

1312-796: Is considered by some geographers to be a large bay or marginal sea of the Atlantic Ocean. For those who regard it as a river, it is the widest in the world, with a maximum width of about 220 kilometres (140 mi) and a total surface area of about 35,000 square kilometres (14,000 sq mi). The upper river contains several islands, including Oyarvide Island and the Solís Islands in Argentine waters and Juncal Island , Islote el Matón , Martín García Island and Timoteo Domínguez Island in Uruguayan waters. Because of deposition of sediments from

1394-509: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

1476-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

1558-560: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

1640-582: Is second in length only to the Amazon River . It merges with the Paraguay River and then farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean. The first European to go up the Paraná River was the Venetian explorer Sebastian Cabot , in 1526, while working for Spain. A drought hit the river in 2021, causing a 77-year low. In eastern South America there

1722-665: Is the Colorado River Delta in Mexico, historically covered with marshlands and forests, but now essentially a salt flat. Paran%C3%A1 River (Period: 1971–2000)667 km /a (21,100 m /s) The Paraná River ( Portuguese : Rio Paraná [ˈʁi.u paɾaˈna] ; Spanish: Río Paraná [ˈri.o paɾaˈna] ; Guarani : Ysyry Parana ) is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some 4,880 kilometres (3,030 mi). Among South American rivers, it

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1804-639: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

1886-573: The Baihetan Dam , both in the People's Republic of China ), creating a massive, shallow reservoir behind it. After merging with the Iguazu, the Paraná becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from Encarnación, Paraguay , across the river, is downtown Posadas, Argentina. The river continues its general southward course for about 468 km (291 mi) before making

1968-505: The Guaraní near today's Asunción, and these objects (together with legends of a " Sierra de la Plata " in the South American interior brought back by earlier explorers) inspired him to rename the river "Río de la Plata" ("River of Silver"). The first European colony was the city of Buenos Aires, founded by Pedro de Mendoza on 2 February 1536. This settlement, however, was quickly abandoned;

2050-719: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

2132-633: The Itaipu Dam , which began operating in 1984. For approximately the next 200 km (120 mi), the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the Iguazu River . Further upstream from this confluence, however, the river is dammed by the Itaipu Dam, the third largest hydroelectric power plant in the world (following the Three Gorges Dam and

2214-595: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

2296-628: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

2378-779: The Paranaíba River , Grande River , Tietê River , Paranapanema River , Iguazu River , Paraguay River, and the Salado River , after which it ends in the large Paraná Delta . The Paraguay River flows through the Pantanal wetland, after which its main tributaries include the Pilcomayo River and the Bermejo River , before it ends in the Paraná. The Uruguay's main tributaries include the Pelotas River , Canoas River , Ibicuí River , and

2460-531: The Paraná River (one of the world's longest rivers and La Plata's main tributary) as well as from the Uruguay River and other smaller streams. Currents in the Río de la Plata are dominated by tides reaching to its sources and beyond, into the Uruguay and Paraná rivers. Both rivers are tidally influenced for about 190 kilometres (120 mi). The tidal ranges in the Río de la Plata are small, but its great width allows for

2542-577: The Preliminary Peace Convention of 1828. The blockade caused serious problems to the export-oriented economy of Buenos Aires but indirectly contributed to rural provinces such as Córdoba , allowing producers to sell native products to Buenos Aires at an increased price. In the first naval battle of the Second World War the German pocket battleship Admiral Graf Spee was engaged by

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2624-622: The Royal Navy (RN) cruisers HMS  Exeter and Ajax , and the Royal New Zealand Navy cruiser Achilles , off the estuary of the River Plate in December 1939. The German ship retired up the estuary with a crippled fuel system and put into port at Montevideo. A few days later, rather than fight when believing himself outgunned, her captain scuttled her in the estuary. This engagement

2706-557: The Río Negro . Another significant tributary to the Río de la Plata is the Salado del Sur River . Nomadic aboriginal people inhabited the Río de la Plata region for thousands of years before European settlers arrived, and their descendants continue to live in the region to this day. The Río de la Plata was first explored by the Portuguese in 1512–13. The Spanish first explored it in 1516, when

2788-702: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

2870-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

2952-517: The sábalo ) are commercially important, and they are exploited for heavy internal consumption or for export. The Parana River delta ranks as one of the world's greatest bird-watching destinations. Much of the length of the Paraná is navigable , and the river serves as an important waterway linking inland cities in Argentina and Paraguay with the ocean, providing deepwater ports in some of these cities. The construction of enormous hydroelectric dams along

3034-556: The Brazilian attempt to control the Uruguay river. Near the coast of Ensenada in April 7, four Argentine vessels led by Brown slipped out of port in an unsuccessful attempt to surprise a large Brazilian fleet under the command of Norton. Two brigs were sunk, and a schooner was heavily damaged, resulting in a decisive Brazilian victory that ensured the Imperial blockade of the Río de la Plata until

3116-471: The Rio Paraná forms a massive drainage basin that encompasses much of the southcentral part of South America, essentially including all of Paraguay, much of southern Brazil, northern Argentina, and the southeastern part of Bolivia . If the Uruguay River is counted as a tributary to the Paraná, this watershed extends to cover most of Uruguay as well. The volume of water flowing into the Atlantic Ocean through

3198-597: The Río de la Plata flourished, very little silver was actually remitted to the Crown. Then, Spanish war with Britain and the simultaneous eruption of revolts in the mining regions of Peru led to a shortage of silver, putting strain on the merchant class of Buenos Aires. This caused a schism between merchants who wanted to try to continue reviving the Spanish Empire through silver trade and those who wanted to move on from silver and prioritize agricultural exports, ultimately tearing at

3280-458: The Río de la Plata roughly equals the volume at the Mississippi River delta . This watershed contains a number of large cities, including São Paulo , Buenos Aires , Rosario , Asunción , Brasília , and La Plata . The Paraná and its tributaries provide a source of income and of daily sustenance for fishermen who live along its banks. Some of the species of fish (such as the surubí and

3362-580: The Río de la Plata was blockaded by the Imperial Brazilian Navy , aiming to cripple Argentine finances and resupply their positions in Colonia del Sacramento and Montevideo . Squadrons of the newly independent United Provinces of the River Plate , led by the Irish-Argentine admiral William Brown attempted to break the blockade despite numerical inferiority. In the first major naval engagement of

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3444-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

3526-549: The Uruguay and Paraná rivers at Punta Gorda and flows eastward into the South Atlantic Ocean . No clear physical boundary marks the river's eastern end; the International Hydrographic Organization defines the eastern boundary of the Río de la Plata as "a line joining Punta del Este , Uruguay and Cabo San Antonio , Argentina ". Though it is generally spoken of as a river, the Río de la Plata

3608-513: The above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from a variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

3690-409: The border between Argentina and Uruguay . The name Río de la Plata is also used to refer to the populations along the estuary, especially the main port cities of Buenos Aires and Montevideo , where Rioplatense Spanish is spoken and tango culture developed. The coasts of the river are the most densely populated areas of Uruguay and Argentina. The Río de la Plata begins at the confluence of

3772-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

3854-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

3936-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

4018-598: The entire country of Paraguay , most of Uruguay , and northern Argentina . Making up about one fourth of the continent's surface, it is the second largest drainage basin in South America (after the Amazon basin ) and one of the largest in the world. The main rivers of the La Plata basin are the Paraná River , the Paraguay River (the Paraná's main tributary), and the Uruguay River . The Paraná River's main tributaries include

4100-595: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

4182-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

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4264-771: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

4346-408: The fabric of the Río de la Plata region's relationship with the Spanish Empire. In 1806 and 1807 the river was the scene of an important British invasion that aimed to occupy the area and was defeated by the local garrison and population. Conflict in the region intensified after the independence of the former Spanish and Portuguese colonies in the first quarter of the 19th century. Interests in

4428-512: The failure to establish a settlement on the estuary led to explorations upriver and the founding of Asunción in 1537. The area was visited by Francis Drake 's fleet in early 1578, in the early stages of his circumnavigation. Buenos Aires was re-founded by Juan de Garay on 11 June 1580. During the colonial era, the Río de la Plata was made the center of the Governorate of the Río de la Plata . The Río de la Plata region, particularly Buenos Aires ,

4510-488: The first time, entering it for about 23 leagues (110 km) to near the present city of Rosario . Explorer Sebastian Cabot made a detailed study of the river and its tributaries and gave it its modern name. He explored the Paraná and Uruguay rivers between 1526 and 1529, ascending the Paraná as far as the present-day city of Asunción , and also explored up the Paraguay River. Cabot acquired silver trinkets trading with

4592-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

4674-624: The fleet system authorized by the Spanish Crown, and therefore was generally considered "illicit." However, under the monarchy of the Spanish Habsburgs , the line between licit and illicit trade was quite blurry. Crown officials and military outposts in Buenos Aires often relied upon profits from illicit trade to support their administrative structures. Under the Bourbon monarchy, the governorate

4756-571: The frigate 25 de Mayo , sank after the battle as a result of the damage received. In 8–9 February, an Argentine fleet led by Brown engaged the Third Division of the Imperial Navy on the Uruguay River, inflicting heavy casualties against a disorganized Brazilian squadron. The Argentines routed the Third Division, capturing or destroying fifteen Brazilian vessels whilst losing none and frustrating

4838-400: The geographer, the Río de la Plata may be considered a river, an estuary, a gulf , or a marginal sea . If considered a river, it is the widest in the world, with a maximum width of 220 kilometres (140 mi). The river is about 290 kilometres (180 mi) long and widens from about 2 kilometres (1.2 mi) at its source to about 220 kilometres (140 mi) at its mouth. It forms part of

4920-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

5002-476: The heavy stream load carried down from the river's tributaries, the islands in the Río de la Plata generally grow over time. A submerged shoal , the Barra del Indio , divides the Río de la Plata into an inner freshwater riverine portion and an outer brackish estuarine portion. The shoal is located approximately between Montevideo and Punta Piedras (the northwest end of Samborombón Bay ). The inner fluvial zone

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5084-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

5166-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

5248-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

5330-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

5412-428: The name served as an inspiration for one of Argentina's most important football clubs, Club Atlético River Plate . A more literal translation of the name is "Silver River", though this is virtually never used in practice. The Río de la Plata is a habitat for the loggerhead sea turtle , green sea turtle , leatherback sea turtle , the rare La Plata dolphin , and many species of fish. Estuary An estuary

5494-631: The navigator Juan Díaz de Solís traversed it during his search for a passage between the Atlantic and the Pacific Oceans, calling it the Mar Dulce, or "freshwater sea". The Portuguese navigator Ferdinand Magellan briefly explored the estuary in 1520 before his expedition continued its circumnavigation, and in 1521, Cristóvão Jacques also explored the Plate River estuary and ascended the Parana River for

5576-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

5658-437: The river's length has blocked its use as a shipping corridor to cities further upstream, but the economic impact of those dams offsets this. The Yacyretá Dam and the Itaipu Dam on the Paraguay border have made the small, largely undeveloped nation of Paraguay the world's largest exporter of hydroelectric power . Due to its use for oceangoing ships, measurements of the water tables extend back to 1904. The data correlates with

5740-421: The river, most notably the poorer merchants and residents in the low-lying areas of Encarnación, a major city on the southern border of Paraguay. River levels rose dramatically upon completion of the dam, flooding out large sections of the city's lower areas. From the confluence with the Paraguay River, the Paraná again turns to the south for another approximately 820 km (510 mi) through Argentina, making

5822-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

5904-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

5986-722: The territories and the navigation rights over the Platine region played a major role in many armed conflicts throughout the century, including the Argentine civil wars , the Cisplatine and Platine wars, and the Paraguayan War . The river was blockaded by Brazil from 1826 to 1828 , by the French from 1838 to 1840 and by an Anglo-French alliance from 1845 to 1850 . During the Cisplatine War ,

6068-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

6150-465: The war, an Argentine squadron left port in the early hours of February 9 to challenge the blockade. The battle was inconclusive, with the Argentine fleet breaking contact and the Brazilian admiral failing to give chase. In July 29, a Brazilian fleet led by the English admiral James Norton engaged Brown's fleet near Ensenada . Norton split his force, catching the Argentine line between two fires and causing significant casualties. William Brown's flagship,

6232-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

6314-619: The water column and in sediment , making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet

6396-486: The water density discontinuities. They play an important role in the reproductive processes of fish species. The Río de la Plata's drainage basin (sometimes called the Platine basin or Platine region) is the 3,170,000 km (1,220,000 sq mi)-3,182,064 km (1,228,602 sq mi) hydrographical area that drains to the Río de la Plata. It includes areas of southeastern Bolivia , southern and central Brazil ,

6478-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

6560-489: Was a significant site of trade throughout the 17th century. The Crown initially intended Buenos Aires to be a military establishment for the protection of the Potosí mines , but it soon became evident that a settlement large enough to provide military defense would attract trade. The primary export was silver from the mines of Potosí, and imports generally included European luxury goods, slaves, and sugar. This trade occurred outside of

6642-544: Was elevated to the Viceroyalty of the Río de la Plata in 1776. This occurred as a result of the Bourbon Reforms , which attempted to restore the decaying wealth of the Spanish Crown. The reforms elevated the status of trade along the Río de la Plata and expanded what constituted "legal" trade so that the Crown could tax trade which had previously been "contraband." However, the plan did not go as intended. Although trade along

6724-468: Was part of the early Battle of the Atlantic . The historical English name "River Plate" uses an obsolete sense of the word "plate", which was used extensively as a term for "silver" or "gold" from the 12th century onwards, especially in Early Modern English . The estuary has been known as the River Plate or Plate River in English since at least the time of Francis Drake. This English version of

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