Amazonia marine ecoregion

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Amazonia marine ecoregion
Amazon Reef.png
The Amazon Reef, discovered only in 2012, extends across the ecoregion.
Amazonia marine ecoregion.png
Marine ecoregion boundaries (red line)
LocationBrazil
Coordinates 0°12′N48°00′W / 0.2°N 48°W / 0.2; -48 (Guianan marine ecoregion)
Type marine ecoregion
Part of Tropical Atlantic realm, North Brazil Shelf province
Surface area384,566 square kilometres (148,482 sq mi) [1]

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 (the other being the Guianan marine ecoregion) in the North Brazil Shelf province, [2] a large marine ecosystem (LME). It is thus part of the Tropical Atlantic realm. [3] [4] [5]

Contents

Physical setting

The ecoregion is bounded on the west at the Brazil-French Guiana border, where the North Brazil Current splits - part continuing northwest as the Guiana Current, part turning north. 850 miles to the southeast, the ecoregion transitions to the Northeastern Brazil marine ecoregion at the mouth of the Parnaiba River. The Amazonia ecoregion extends 200 miles offshore from the coast, covering the shelf and slope of the continental shelf. The bordering coast is low and flat, and characterized by mangrove forests of the Amapá mangroves terrestrial ecoregion, the sandy forests of the Northeastern Brazil restingas, and the Marajó várzea (floodplain forest) of the Amazon delta. [1] Aside from the Amazon, the major rivers feeding the Amazonia marine region include the clearwater Tocantins River and the Mearim River.

The continental shelf is relatively smooth and shallow, with a drop on the shelf about half-way to the north. The deepest point is −2,047 metres (−6,716 ft), and the average is −49 metres (−161 ft). [4] 38% of the ecoregion is less than 200 meters in depth, and 54% is greater than 1,000 meters. Underneath the freshwater outflow of the Amazon is a carbonate reef structure, the Amazon Reef. This deep reef is colonized by sponges and other filter feeders, under conditions of low light and dense particulates. [6]

Currents and climate

Flowing northwest through the ecoregion is the warm North Brazil Current (NBC), the northern continuation of the Central) South Equatorial Current bringing warm water from the South Atlantic Ocean. The NBC is additionally fed by the outflow of the Amazon River, lowering the salinity and raising the turbidity of the water through the Amazonia marine area. In the summer and fall, the NBC generates counter-cycles that flow north into the Equatorial Counter Current (and the North Atlantic); in the spring the NBC continues straight through the Amazonia ecoregion to feed the Gianan Current and eventually the Caribbean Sea. The NBC flows at a rate averaging 26 Sverdrups (Sv), at a mean speed of 60–100 centimetres per second (1.3–2.2 mph) during the winter months, then slacks off somewhat in the summer as the Intertropical Convergence Zone (ITCZ) shifts north. [7] [8] The winds over the surface range from northeasterly to southeasterly. [9]

A large outflow of fresh and brackish water from the Amazon mouth - the Amazon river plume - extends through the middle of the Amazonia ecoregion, being pulled north by the NBC. Combined with rainfall this lowers the salinity of the ecoregion's waters, to levels that average 35-36.75 ppm. Surface temperatures range from 22–29 °C (72–84 °F). [10]

Animals / Fish

The coast is dominated by the Amazon delta and extensive mangrove forests. The inlets, swamps and lagoons provide shelter, food, and breeding habitat for birds, invertebrates and fish. [1] Offshore, the continental shelf supports soft mud-bottom communities. [1] Aside from the Amazon Reef structure, the bottom is mostly sand, mud and gravel in the deeper water. [11]

Near shore, the most important commercial fisheries are for shrimp, primarily Southern brown shrimp ( Farfantepenaeus subtilis ) and Red spotted shrimp ( Farfantepenaeus brasiliensis ). [12]

Conservation status

Many of the terrestrial protected areas on the coast have marine components, such that about 12% of the ecoregion is protected, including: [4]

Related Research Articles

The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature (WWF), the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species dynamics, and environmental conditions". For example, based on their levels of endemism, Madagascar gets multiple listings, ancient Lake Baikal gets one, and the North American Great Lakes get none.

<span class="mw-page-title-main">Orinoco Delta</span> Delta region of the Orinoco River

The Orinoco Delta is a vast river delta of the Orinoco River, located in eastern Venezuela.

<span class="mw-page-title-main">Maranhão mangroves</span> Mangrove ecoregion of northern Brazil

The Maranhão mangroves is a mangrove ecoregion of northern Brazil. It supports half of the shorebird population of the country. The combination of flat land, heavy rainfall and high tides causes the mangroves to extend up to 40 kilometres (25 mi) inland, where they are interspersed with other rainforest species.

<span class="mw-page-title-main">Amazon biome</span> Ecological region of South America

The Amazon biome contains the Amazon rainforest, an area of tropical rainforest, and other ecoregions that cover most of the Amazon basin and some adjacent areas to the north and east. The biome contains blackwater and whitewater flooded forest, lowland and montane terra firma forest, bamboo and palm forest, savanna, sandy heath and alpine tundra. Some areas of the biome are threatened by deforestation for timber and to make way for pasture or soybean plantations.

<span class="mw-page-title-main">Marajó várzea</span>

The Marajó várzea (NT0138) is an ecoregion of seasonally and tidally flooded várzea forest in the Amazon biome. It covers a region of sedimentary islands and floodplains at the mouth of the Amazon that is flooded twice daily as the ocean tides push the river waters onto the land. The flooded forests provide food for a wide variety of fruit-eating fish, aquatic mammals, birds and other fauna. It has no protected areas and is threatened by cattle and water-buffalo ranching, logging and fruit plantations.

<span class="mw-page-title-main">Guianan moist forests</span>

The Guianan moist forests (NT0125) is an ecoregion in the east of Venezuela, north of Brazil and the Guyanas. It is in the Amazon biome. The climate is hot and humid, with two rainy seasons each year. As of 1996 the tropical rainforest habitat was relatively intact, although there were mounting threats from illegal logging and gold mining.

<span class="mw-page-title-main">Amazon–Orinoco–Southern Caribbean mangroves</span>

The Amazon–Orinoco–Southern Caribbean mangroves (NT1401) is an ecoregion along the coasts of Colombia, Venezuela, Guyana, Suriname, French Guiana and Brazil.

<span class="mw-page-title-main">Guianan mangroves</span> Coastal ecoregion of southeastern Venezuela, Guyana, Suriname and French Guiana

The Guianan mangroves (NT1411) is a coastal ecoregion of southeastern Venezuela, Guyana, Suriname, French Guiana and Brazil. The mangroves provide an important habitat for migrating birds that winter in the area. Large areas are intact, although they are threatened by destruction of the trees for timber and to make way for agriculture, and from upstream agricultural and industrial pollution.

<span class="mw-page-title-main">Amapá mangroves</span> Ecoregion in Amapá, Brazil

The Amapá mangroves (NT1402) is an ecoregion along the Atlantic coast of the state of Amapá in Brazil. The low coastal plain has been formed from recent sedimentation, including sediments deposited by the rivers and sediments carried northward from the mouth of the Amazon River by strong currents and deposited by the tides. The extensive mangroves grow on the newly formed coastal mudflats and along the edges of estuaries. They merge into freshwater várzea flooded forests further inland. The ecoregion is generally well-preserved, although excessive extraction of natural resources including timber and shrimps is a concern.

<span class="mw-page-title-main">Pará mangroves</span> Mangrove ecoregion in Northern Brazil

The Pará mangroves (NT1427) is an ecoregion along the Atlantic coast of the state of Pará in Brazil. They constitute the western extension of the Maranhão mangroves ecoregion. The mangroves are relatively intact, although they are under some pressure from agriculture and logging.

<span class="mw-page-title-main">Paramaribo swamp forests</span>

The Paramaribo swamp forests (NT0149) is an ecoregion in the coastal plain of Suriname covering a strip of land that is almost always flooded by fresh waters. It transitions into saline mangrove swamps towards the coast, and into submontane forests towards the interior.

The East African coral coast is a marine ecoregion along the eastern coast of Africa. It extends along the coasts of Kenya, Tanzania, and northern Mozambique, from Lamu in Kenya to Angoche in Mozambique. It adjoins the Northern Monsoon Current Coast ecoregion to the north, and the Bight of Sofala/Swamp Coast ecoregion to the south.

The Bight of Sofala/Swamp Coast is a marine ecoregion along the eastern coast of Africa, characterized by extensive mangrove swamps and coastal wetlands. It extends along the coast of Mozambique, from Angoche to the Bazaruto Archipelago. It adjoins the East African coral coast ecoregion to the north, and the Delagoa ecoregion to the south.

<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">Northeastern Brazil marine ecoregion</span> Tropical marine ecoregion

The Northeastern Brazil marine ecoregion covers the coastal marine environment around the Northeast Region of Brazil. The marine ecoregion extends from the mouth of the Parnaíba River in the west around the eastern point of the Brazilian mainland and south to the Bay of All Saints. The warm South Equatorial Current feeds warm tropical water into the region from the east. The Northeastern Brazil ecoregion is one of two coastal marine ecoregions in the Tropical Southwest Atlantic marine province. It is thus part of the Tropical Atlantic realm.

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

The Eastern Brazil marine ecoregion covers the coastal marine environment along the middle of the east coast of Brazil. The ecoregion extends south from the Bay of All Saints to Cabo Frio just east of the city of Rio de Janeiro. The Brazil Current enters from the east, feeding warm subtropical water to the south along the coast. The influence of the tropical waters leaves the ecoregion relatively oligotrophic. The Eastern Brazil ecoregion is one of two coastal marine ecoregions in the Tropical Southwest Atlantic marine province. It is thus part of the Tropical Atlantic realm. .

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

The Southeastern Brazil marine ecoregion covers the warm coastal waters to 250 miles offshore of southeastern Brazil, from the latitude of Rio de Janeiro in the north to Florianópolis in the south. Marine diversity is supported by local upwellings in the north and the inflow of the Brazil Current. The region is one of transition from a tropical to a warm temperate environment. The marine 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">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">Rio de la Plata marine ecoregion</span> Tropical marine ecoregion

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. .

References

  1. 1 2 3 4 "Setting Geographic Priorities for Marine Conservation in Latin America and the Caribbean" (PDF). The Nature Conservancy. Retrieved June 30, 2022.
  2. "North Brazil Shelf". One Shared Ocean. Retrieved June 30, 2022.
  3. 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)
  4. 1 2 3 "Amazonia". Digital Observatory for Protected Areas (DOPA). Retrieved June 30, 2022.
  5. "Amazonia". MarineRegions.org. Retrieved July 8, 2022.
  6. Moura, Rodrigo L.; et al. (2016). "An extensive reef system at the Amazon River mouth". Science Advances. 2 (4). Science: e1501252. doi:10.1126/sciadv.1501252. PMC   4846441 . PMID   27152336.
  7. "North Brazil Current". University of Miami. Retrieved June 30, 2022.
  8. Giachini Tosetto, Everton; Bertrand, Arnaud; Neumann-Leitão, Sigrid; Nogueira Júnior, Miodeli (11 January 2022). "The Amazon River Plume". Scientific Reports. 12 (1). Nature: 537. doi:10.1038/s41598-021-04165-z. PMC   8752809 . PMID   35017566. S2CID   257058194.
  9. "The Guiana Current". University of Miami. Retrieved June 30, 2022.
  10. "Guianan Current". Encyclopedia Britannica. Retrieved July 1, 2022.
  11. Isaac, Victoria J.; Ferrari, Stephen F. (2017). "Assessment and management of the North Brazil Shelf Large Marine Ecosystem". Environmental Development. 22: 97–110. doi: 10.1016/j.envdev.2016.11.004 . Retrieved July 1, 2022.
  12. "Estuary & Amazon Coast". Amazon Waters. Retrieved July 14, 2022.
  13. "Cabo Orange National Park - Brazil" (PDF). RAMSAR. Retrieved July 2, 2022.