The Parnaíba River ( ) is a river in

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, which forms the border between the states of

Maranhão Maranhão () is a States of Brazil, state in Brazil. Located in the country's Northeast Region, Brazil, Northeast Region, it has a population of about 7 million and an area of and it is divided into 217 municipalities. Clockwise from north, it ...

and

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

. 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 range, and flows northeastward to empty into the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

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

Ecology

The fish species richness 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 only 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 foun ...

. 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. It inhabits rivers of tropical and subtropical climates, especially those of the ...

signata''. More than 70% of the fish species in the basin are members of either Characiformes or Siluriformes. The fauna in the

headwaters The headwater of a river or stream is the geographical point of its beginning, specifically where surface runoff water begins to accumulate into a flowing channel of water. A river or stream into which one or many tributary rivers or streams flo ...

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, created in 1996. The river's

delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

has large stands of

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

, 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 i ...

:
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 (''Eudocimus ruber'') and rufous crab hawk (''Buteogallus aequinoctialis''). Two species of aquatic turtles are endemic to the general region, the Maranhão slider (''Trachemys adiutrix'') that is found in the delta and the side-necked turtles '' Mesoclemmys perplexa'' 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