The Parnaíba River ( pt, Rio Parnaíba) is a river in

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, which forms the border between the states of

Maranhão Maranhão () is a state in Brazil. Located in the country's Northeast Region, it has a population of about 7 million and an area of . Clockwise from north, it borders on the Atlantic Ocean for 2,243 km and the states of Piauí, Tocantins and ...

and

Piauí Piaui (, ) is one of the states of Brazil, located in the country's Northeast Region. The state has 1.6% of the Brazilian population and produces 0.7% of the Brazilian GDP. Piaui has the shortest coastline of any coastal Brazilian state at 66&n ...

. Its main course is long and the Parnaíba River Basin covers .Ramos, T.P.A.; Ramos, R.T.C.; and Ramos, S.A.Q.A. (2014).
Ichthyofauna of the Parnaíba river Basin, Northeastern Brazil.
' Biota Neotrop. 14(1). The Parnaíba River rises in the

Chapada das Mangabeiras The Chapada das Mangabeiras is a mountain range in central Brazil. The range runs northwest–southeast, and separates the basin of the Tocantins River to the southwest from the upper basin of the Parnaiba River to the northeast. The range also fo ...

range, and flows northeastward to empty into the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, being the longest river entirely located within Brazil's Northeast Region. The middle and upper regions of this river are separated by the pt, Boa Esperança Hydroelectric Power Plant dam, but is otherwise navigable.

Ecology

The fish

species richness Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative a ...

in the Parnaíba River Basin has traditionally been considered impoverished, but this has been disproven by recent surveys, which have recorded about 140 native species (including several that remain undescribed) and about 40% of these are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

. One of the basin endemics is the freshwater stingray ''

Potamotrygon ''Potamotrygon'' is a genus of freshwater stingrays in the family Potamotrygonidae native to the rivers of South America, and sometimes seen in the aquarium trade. Like other stingrays, the fishes of this genus have venomous barbs at the base of ...

signata''. More than 70% of the fish species in the basin are members of either

Characiformes Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationsh ...

Siluriformes Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

. The fauna in the

headwaters The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source. Definition The ...

has not yet been thoroughly surveyed. In addition to the natives, there are seven introduced fish species in the basin. The river delta is protected by the

Delta do Parnaíba Environmental Protection Area The Delta do Parnaíba Environmental Protection Area ( pt, Área de Proteção Ambiental Delta do Parnaíba) is a federally-administered environmental protection area that covers parts of the coasts of the states of Maranhão, Piauí and Ceará ...

, created in 1996. The river's

delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

has large stands of

mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...

, as well as dunes, beaches, marshes and other habitats.

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

:
Delta do Parnaíba.
' Retrieved 28 July 2014. The delta is considered an

Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Int ...

and is home to species such as

scarlet ibis The scarlet ibis (''Eudocimus ruber'') is a species of ibis in the bird family Threskiornithidae. It inhabits tropical South America and part of the Caribbean. In form, it resembles most of the other twenty-seven extant species of ibis, but it ...

(''Eudocimus ruber'') and

rufous crab hawk The rufous crab hawk (''Buteogallus aequinoctialis'') or rufous crab-hawk, is a Near Threatened species of bird of prey in subfamily Accipitrinae, the "true" hawks, of family Accipitridae.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Clara ...

(''Buteogallus aequinoctialis''). Two species of aquatic turtles are endemic to the general region, the

Maranhão slider The Maranhão slider (''Trachemys adiutrix''), also commonly known as the Brazilian slider www.reptile-database.org. or Carvalho's slider, is a species of turtle in the family Emydidae. Geographic range ''Trachemys adiutrix'' is endemic to nor ...

(''Trachemys adiutrix'') that is found in the delta and the side-necked turtles ''

Mesoclemmys perplexa ''Mesoclemmys perplexa'' is a species of turtle from Northeast Brazil The Northeast Region of Brazil ( pt, Região Nordeste do Brasil; ) is one of the five official and political regions of the country according to the Brazilian Institute of ...

'' found inland, but neither is entirely restricted to the Parnaíba River Basin.Bour, R.; and Zaher, H. (2005).
A new species of Mesoclemmys, from the open formations of northeastern Brazil (Chelonii, Chelidae).
' Pap. Avulsos Zool. (São Paulo) 45(24).

References

{{DEFAULTSORT:Parnaiba River Rivers of Maranhão Rivers of Piauí