Rio de la Plata marine ecoregion

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Rio de la Plata marine ecoregion
River Plate.jpg
Buenos Aires is in northwest of the bay. Note the turbidity front, and freshwater flow channels.
Rio de la Plata marine ecoregion.png
Marine ecoregion boundaries (inside red line)
Ecology
Realm Temperate South America
Province Warm Temperate Southwestern Atlantic
Geography
Country Uruguay, Argentina

The Rio de la Plata marine ecoregion covers the mouth of the Rio de la Plata, between the shores of Argentina an Uruguay and inshore of the continental shelf of the Uruguay - Buenos Aires Shelf marine ecoregion. The ecoregion is an important reproductive and nursery ground for marine life, as the river runoff provides nutrients for larval and juvenile phases, the shallow and protective waters admit light, and there is of mixing fresh and salt waters. The region is in the Warm Temperate Southwest Atlantic marine province, a part of the Tropical Atlantic realm. [1] [2] [3] [4] . [5]

Contents

Physical setting

The ecoregion's eastern boundary is a line across the mouth of the river where it meets the sea, with Punta del Este, Uruguay on the north and San Clemente del Tuyú on Cape San Antonio, Argentina on the south. The ecoregion reaches 450 km to the west, up the Uruguay River to Nuevo Berlín, Uruguary. The terrestrial ecoregion to the north is the Uruguayan savanna, to the south is the Humid Pampas; on the west upstream of the estuary is the Paraná flooded savanna. [6] [7] The major rivers feeding the Rio de la Plata are the Paraná River and the Uruguay River, with annual average discharges of 16,000 and 6,000 m2/s, respectively. The bay itself is shallow with a flat sediment bottom crossed by channels (particularly along the Uruguary side) and sediment bars (facing Buenos Aires). [5]

The ecoregion covers 32,015 square kilometres (12,361 sq mi). The deepest point is −39 metres (−128 ft), and the average depth is 8.4 metres (28 ft). [2]

Currents and climate

The main current is the freshwater flow of the rivers from the interior. At the mouth of the ecoregion, the cold, nutrient-rich Malvinas Current (MC) (also called the Falkland Current) flows north in a 100-km wide band over the Patagonian Shelf. [8] Immediately to the north, the MC meets the warm Brazil Current flowing down from the north. [9]

Animals / Fish

Species of freshwater and mixohaline (brackish) types are affected by two large flow corridors of the tributary rivers. The freshwaters of the Paraná River flow along the Argentine coast on the south, while a corridor of the Uruguay River runs along the Uruguay side on the north. There is a narrow mixing corridor of the two, and the salinity front (located in a band across the ecoregion's meeting the open ocean) shifts with the winds and seasons.

Black drum (Pogonias cromis), Whitemouth croaker ( es:Micropogonias furnieri ), and King Weakfish ( Macrodon ancylodon ) spawn in the bottom salinity front. [5] Fish that take refuge in the mixed fresh and salt waters also include the Banded croaker ( Paralonchurus brasiliensis ) and various species of Flounder (genus Paralichthys ).

The surface salinity front supports large numbers of Argentine anchovy ( Engraulis anchoita ) and Chub mackerel ( Scomber japonicus ). The turbidity front is located across the bay at about the midpoint of the ecoregion. Because of poor penetration of light in the turbidity front, species richness is low. But the species that do exist in the turbidity front are found in large numbers, notably zooplankton, Whitemouth croaker, and Menhaden ( Brevoortia aurea ). The salt marshes on the margins are characterized by burrowing crabs ( Chasmagnathus granulata ).

Conservation status

The primary threats to the region are algae blooms, disruption of the benthic (bottom) habitats, and pollution. Some of the terrestrial protected areas on the coast have marine components, such that about 2% of the ecoregion is protected, including: [2]

Related Research Articles

<span class="mw-page-title-main">Geography of Argentina</span> Geographic features of Argentina

The geography of Argentina describes the geographic features of Argentina, a country located in the Southern Cone of South America. Bordered by the Andes in the west and the South Atlantic Ocean to the east, its neighbouring countries are Chile to the west, Bolivia and Paraguay to the north, and Brazil and Uruguay to the northeast.

<span class="mw-page-title-main">Río de la Plata</span> River or estuary in South America

The Río de la Plata, 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 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).

<span class="mw-page-title-main">Uruguay River</span> River in South America

The Uruguay River is a major river in South America. It flows from north to south and forms parts of the boundaries of Brazil, Argentina, and Uruguay, separating some of the Argentine provinces of La Mesopotamia from the other two countries. It passes between the states of Santa Catarina and Rio Grande do Sul in Brazil; forms the eastern border of the provinces of Misiones, Corrientes, and Entre Ríos in Argentina; and makes up the western borders of the departments of Artigas, Salto, Paysandú, Río Negro, Soriano, and Colonia in Uruguay.

<span class="mw-page-title-main">Paraná River</span> River in South America

The Paraná River (Portuguese: Rio Paraná ; is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some 4,880 kilometres. Among South American rivers, it 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.

<span class="mw-page-title-main">Paraguay River</span> River of Argentina, Brazil and Paraguay

The Paraguay River is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about 2,695 kilometres (1,675 mi) from its headwaters in the Brazilian state of Mato Grosso to its confluence with the Paraná River north of Corrientes and Resistencia.

The Falkland Current is a cold water current that flows northward along the Atlantic coast of Patagonia as far north as the mouth of the Río de la Plata. This current results from the movement of water from the West Wind Drift as it rounds Cape Horn. It takes its name from the Falkland Islands. This cold current mixes with the tropical Brazil Current in the Argentine Sea, giving it its temperate climate.

<span class="mw-page-title-main">Argentine Naval Prefecture</span>

The Argentine Naval Prefecture is a service of Argentina's Security Ministry charged with protecting the country's rivers and maritime territory. It therefore fulfills the functions of other countries' coast guards, and furthermore acts as a gendarmerie force policing navigable rivers.

<span class="mw-page-title-main">Río de la Plata Basin</span> Drainage basin in eastern South America

The Río de la Plata basin, more often called the River Plate basin in scholarly writings, sometimes called the Platine basin or Platine region, is the 3,170,000-square-kilometre (1,220,000 sq mi) hydrographical area in South America that drains to the Río de la Plata. It includes areas of southeastern Bolivia, southern and central Brazil, 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 and one of the largest in the world.

<span class="mw-page-title-main">Humid Pampas</span>

The Humid Pampas is an extensive ecoregion of flat, fertile grassland of loessic origin in Argentina. It has a precipitation average of 900 mm per year, in contrast with the Dry Pampas to the west, which average less than 700 mm.

<span class="mw-page-title-main">Uruguayan savanna</span> Terrestrial ecoregion in South America

The Uruguayan savanna, also known as the Brazilian-Uruguayan savanna, is a subtropical grassland and savanna ecoregion which includes all of Uruguay and southernmost Brazil, along with portions of Argentina along the Uruguay River. In Brazil, this ecoregion is known as Pampas.

<span class="mw-page-title-main">Short-tailed river stingray</span> Species of cartilaginous fish

The short-tailed river stingray is a species of river stingray native to the Río de la Plata Basin in South America. It is sometimes known as the giant freshwater stingray, but this name is typically used for the southeast Asian Urogymnus polylepis.

In oceanography, a front is a boundary between two distinct water masses. The formation of fronts depends on multiple physical processes and small differences in these lead to a wide range of front types. They can be as narrow as a few hundreds of metres and as wide as several tens of kilometres. While most fronts form and dissipate relatively quickly, some can persist for long periods of time.

<span class="mw-page-title-main">Argentina–Uruguay border</span> International border

The Argentina–Uruguay border is a line of 579 km marked by the Uruguay River, and is the border between Argentina and Uruguay. It starts in a triple border Argentina-Uruguay-Brazil, at the mouth of the Quaraí River in the Uruguay. The course follows the Uruguay river, passing west of the Uruguayan departments of Artigas, Salto, Paysandu, Rio Negro, Soriano and Colonia and the Argentine provinces of Corrientes, Entre Rios and Buenos Aires, until the confluence of the Uruguay and the Paraná rivers into the Rio de la Plata.

<span class="mw-page-title-main">Temperate South America</span> Biogeographic region of the Earths seas

Temperate South America is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of South America, including both the Pacific and Atlantic coasts of the continent and adjacent islands. It also includes the remote Gough Island and Tristan da Cunha in the South Atlantic Ocean.

<span class="mw-page-title-main">Guianan marine ecoregion</span> Tropical marine ecoregion

The Guianan marine ecoregion stretches along the middle of the northeast coast of South America, touching Venezuela, Guyana, Suriname and French Guiana. It extends about 200 miles offshore, with the warm Guianan Current moving east-to-west through the region. This current brings in fresh, turbid waters from the mouth of the Amazon River to the east. As the current exits the ecoregion to the west it contributes an estimated 70% of the waters of the Caribbean Sea. A very large oil field has been recently discovered in the Guyana-Suriname Basin of the ecoregion. The Guianan is one of two ecoregions in the North Brazil Shelf province, a Large marine ecosystem (LME). The Guianan is thus part of the larger Tropical Atlantic realm.

<span class="mw-page-title-main">Amazonia marine ecoregion</span> Tropical marine ecoregion

The Amazonia marine ecoregion covers the coastal marine environment off the mouth of the Amazon River on the continental shelf of Brazil. The warm North Brazil Current moves east-to-west across the river's outlet, carrying turbid, fresh water to the northwest towards the Caribbean Sea. The Amazonia is one of two ecoregions in the North Brazil Shelf province, a large marine ecosystem (LME). It is thus part of the Tropical Atlantic realm.

<span class="mw-page-title-main">Rio Grande marine ecoregion</span> Tropical marine ecoregion

The Rio Grande marine ecoregion covers the waters offshore of the southern Brazilian states of Rio Grande do Sul and Santa Catarina. The ecoregion stretches along 500 miles of sandy beach coast, and 200 miles out to sea. The warm Brazil Current flows south through the region in parallel with the coast. The continental shelf is smooth and flat, with the bottom mostly sand and mud. Overfishing is a problem, but marine life in recent years has benefited from measures such as a 2018 ban on motorized shrimp trawler fishing within 12 miles of the Rio Grande do Sul coast. The Rio Grande ecoregion is one of four coastal marine ecoregions in the Warm Temperate Southwestern Atlantic marine province. It is thus part of the Temperate South America realm. .

<span class="mw-page-title-main">Uruguay - Buenos Aires Shelf marine ecoregion</span>

The Uruguay - Buenos Aires Shelf marine ecoregion covers waters offshore of Uruguay, the mouth of the Rio de la Plata), and Buenos Aires Province of Argentina. It has an area of 258,490 square kilometres (99,800 sq mi) and a coastline of 1,300 kilometres (810 mi). Marine biodiversity is very high due to the mixing of currents, the mixing of fresh and salt water, the mixing of temperatures, and the broad, shallow continental shelf. Large amounts of nutrients arrive from the northwest flowing Malvinas Current and from the continental runoff of the Rio de la Plata. Aside from high populations of fish there are colonies of marine mammals, sea turtles, and seabirds.

<span class="mw-page-title-main">North Patagonian Gulfs marine ecoregion</span> Marine ecoregion

The North Patagonian Gulfs marine ecoregion covers the gulfs and continental shelf of the middle Patagonian coast of Argentina. As the name suggests, the coast is indented with large gulfs - San Matías Gulf (north), Golfo Nuevo (middle) and San Jorge Gulf (south). The broad, protected areas and rocky reefs support abundant fisheries. The abundance of rocks, promontories and islands support breeding sites for marine mammals and colonies of seabirds. The area is, however, under pressure from over-harvesting of mollusk and crustacean beds, and from development and tourism. The entire ecoregion is on the Patagonian Shelf. The ecoregion is part of the Magellanic marine province. It is thus part of the Temperate South America realm. .

References

  1. Spalding, MD; Fox, Helen; Allen, Gerald; Davidson, Nick. "Marine Ecoregions of the World: A Bioregionalization of Coastal and Shelf Areas". Bioscience. Retrieved June 30, 2022.{{cite web}}: CS1 maint: multiple names: authors list (link)
  2. 1 2 3 "Rio de la Plata". Digital Observatory for Protected Areas (DOPA). Retrieved September 9, 2022.
  3. "Rio de la Plata". MarineRegions.org. Retrieved September 9, 2022.
  4. "Patagonian Shelf". One Shared Ocean. Retrieved September 9, 2022.
  5. 1 2 3 Alejandro BRAZEIRO; Marcelo ACHA; Hermes MIANZAN; Mónica GÓMEZERACHE; V. FERNÁNDEZ. "Aquatic Priority Areas for the Conservation and Management of the Ecological Integrity of the Río de la Plata and its Maritime Front". PNUD Project / GEF RLA/99/G31. Retrieved March 22, 2023.
  6. "Map of Ecoregions 2017". Resolve, using WWF data. Retrieved March 22, 2023.
  7. "Setting Geographic Priorities for Marine Conservation in Latin America and the Caribbean" (PDF). The Nature Conservancy. Retrieved June 30, 2022.
  8. "The Malvinas Current". University of Miami. Retrieved March 18, 2023.
  9. "Brazil Current". University of Miami. Retrieved September 9, 2022.