New Guinea Rivers & Streams

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View of meandering river entering the sea. North coast of West Papua, Indonesia.
© WWF-Canon / John RATCLIFFE

About the Area

New Guinea's central highlands divide the island into two faunal provinces, with the southern rivers containing the greater share of diversity.
For example, within the enormous southward-flowing Fly River alone, there are over 100 fish species, representing 33 families.

The ecoregion is known for distinctive island freshwater fauna with high endemism and unusual adaptive radiations. It also shares with Australia a diverse freshwater crab fauna of the family Parathelphusidae.

The incessant rains fill the rivers and streams, which often spill out into adjacent floodplains and swamps. Seasonal flooding of swamps and floodplains is important in maintaining the freshwater species of this region.
Size:
458,000 sq. km (183,000 sq. miles)

Habitat type:

Small Rivers

Geographic Location:
Southeast Asia: Indonesia and Papua New Guinea

Conservation Status:
Relatively Stable/Intact
Local Species
The diverse assemblage of spectacular forms found in New Guinea's freshwaters include sharks, sawfish, and large saltwater crocodiles. Imperiled endemic fish species include Oktedi rainbowfish (Melanotaenia oktediensis) and Glass blue-eye (Kiunga ballochi).

Multiple freshwater turtle species are also in danger and include the Fly River turtle (Carettochelys insculpta), two snake-necked turtles (Chelodina parkeri, C. pritchardi), and two soft-shelled turtles (Pelochelys bibroni, P. cantorii). Barramundi (Lates calcarifer) and certain other aquatic species are of great economic importance as commercial food sources.

Featured species

Oktedi rainbowfish (Melanotaenia oktediensis)

The rainbowfishes are a family of small, colourful, freshwater fish that are found in northern and eastern Australia and New Guinea and some other nearby islands.

In Oktedi rainbowfish , body colouration is coppery brown above a prominent mid-lateral line and pale mauve to white below. Body slender and laterally compressed but depth increasing with age. Two dorsal fins, very close together, the first much smaller than the second. May reach a maximum size of 12 cm, but usually less than 10 cm.

Spawning occurs from October to December, with females producing between 100 and 200 eggs. Eggs adhere to water plants and hatching occurs around 9 to 12 days at temperatures between 24 to 28° Celsius. Essentially a carnivore, their natural diet consists of terrestrial insects, small aquatic crustaceans, and insect larvae. Aquatic algae, plant pollens, and small pulpy seeds are also ingested.

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Threats
Deforestation as a result of commercial agriculture and industrial logging, which leads to increased erosion and altered hydrologic regimes, poses one of the most significant threats.

Road building in association with logging has opened up new lands to shifting agriculture. Pollution from mining, industrial logging, agricultural processing, and urban sewage is a serious problem.

Exotics such as Tilapia (Oreochromis mossambica) and Water hyacinth (Eichhornia crassipes), whose population is growing rapidly, place additional stresses; overfishing for both for subsistence use and the commercial trade, threatens native species.

Additionally, wildlife trade threatens reptiles such as the saltwater crocodile (Crocodylus porosus) - heavily hunted in the Sepik River region and elsewhere for its skins and live export.
WWF’s work
WWF PNG's Freshwater Programme is now underway with strong links to Forests, Marine and Species programmes. [New Guinea contains two freshwater Global 200 Ecoregions - New Guinea Rivers and Streams, which covers most of the island, including Papua Province, Indonesia, and Lakes Kutubu and Sentani. These ecoregions are part of a mosaic of several other Global 200 ercoregions, such as the Transfly, Southern New Guinea Lowland Forest, and Southern New Guinea Swamp Forests, and the Bismark Solomon Seas. This overlay of forest, freshwater and marine ecoregions creates great potential for an integrated effort that will contribute greatly to WWF's overall One Global Programme of conservation.]

WWF is currently the only NGO in the region addressing freshwater conservation at country and major catchment level, and the government has too few resources to support widespread wetland conservation and sustainable use programme.

Read more:

WWF: New opportunities for freshwater

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