· Making the Most of Monsoons
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· Looking Ahead

Global 200 Snapshot

The diverse assemblage of species found in New Guinea’s freshwater rivers and streams includes both marine and freshwater species as well as many endemic freshwater species.  

Making the Most of Monsoons

Everyone likes a rainy day now and then, but what about rainy months? New Guinea, the second largest island in the world (after Greenland), gets rain most of the year. During the monsoon season, heavy winds blow in the wet weather. The 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.

Special Features

Rivers and streams drain the high peaks along the central mountain ranges in every direction. The southern rivers have the greatest diversity of species. For example, the Fly River runs 700 miles (1,100 km) and is home to more than 100 fish species from 33 different families.

	The pig-nosed turtle, a member of an ancient family of turtles, is restricted to the southern rivers of New Guinea and northern rivers of Australia. This large freshwater creature uses flippers to swim, just as its marine cousins do -- an unusual trait that indicates that the pig-nosed turtle once lived in the sea but evolved over time to live in rivers, swamps, and lakes.

Wild Side

The diverse species found in New Guinea’s freshwater rivers and streams include marine and freshwater species, including rainbowfish, sharks, sawfish, and saltwater crocodiles. Some species, such as the barramundi, are a favorite food for people. Several species of archerfish swim in these waters. These fish are noted for their ability to knock down insects from overhanging vegetation with squirts of water they shoot from their mouths. Schools of tiny rainbow fish brighten the waterways with a multitude of colors. Rare endemic fish species include Oktedi rainbowfish and glass blue-eyes. Juvenile New Guinea crocodiles, found only in Irian Jaya and Papua New Guinea, use newly flooded swampland habitats bordering rivers and streams. Saltwater crocodiles, found in both fresh and saltwater environments, breed in freshwater. Multiple freshwater turtle species found here are imperiled, including the Fly River turtle, two species of snake-necked turtles, and two species of soft-shelled turtles. Freshwater crayfish are present on the island, as well as several cave shrimps. This ecoregion also shares with Australia a diverse group of freshwater crabs of the family Parathelphusidae. Many other fish swim only in the rivers and streams of this island, like the banded mogurnda, freshwater gudgeon, obscure goby, and Gjellerup's mouth almighty.

Cause for Concern

Industrial logging and clearing of forests for commercial agriculture lead to increased erosion and altered water flows, which pose significant threats to the ecoregion. Road building in association with logging has opened up new lands to agriculture. Pollution from mining is a serious problem in this ecoregion, and pollution from industrial logging, agricultural processing, and urban sewage is also a threat. Overfishing, both for subsistence use and the commercial trade, threatens native species. Invasive exotic species such as tilapia and water hyacinth place additional stresses on native species, and populations of exotics are apparently growing rapidly. Wildlife trade also threatens reptiles such as the saltwater crocodile, which is heavily hunted in the Sepik River region and elsewhere for its skin and live export.

Looking Ahead

Check back soon for more about the conservation of this ecoregion.