Sundaland Rivers and Swamps

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Red mangroves, Sarawak, Borneo, Malaysia.
© WWF-Canon / Terry DOMICO

About the Area

Sundaland is a biogeographical region that comprises the Indonesian islands of Borneo, Sumatra, Java, Bali and Malay peninsula. This ecoregion contains a diversity of freshwater habitats including hill streams, lowland floodplains, and peat swamps. Rivers such as the Kapuas, Pawan, and Pesaguan start in the hills of central Borneo and run southwest, creating swamps and deltas along the sea.

The fish and decapod crustaceans of this ecoregion are remarkably rich and differentiated, with endemic species found in many individual river basins. Known freshwater fish species total 272 in Sumatra (30 endemic) and 394 in Borneo (149 endemic).

The peak of the rainy season in most of Sundaland is December-January.

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Size:
1,000,000 sq. km (400,000 sq. miles)

Habitat type:
Small Rivers

Geographic Location:
Southeast Asia: Brunei, Malaysia, Indonesia (including Sumatra and Borneo), and Singapore

Conservation Status:
Vulnerable
Local Species
Large or fast Cyprinids and loaches, puffers, soles and tiger perches inhabit these areas. Where the water is clear and it's not too deep algae eating fishes such as Crossocheilus and Balitorids become more common. Clown loaches and Bala sharks are examples of common aquarium species found in these environments.

Endemic freshwater fish include several shark catfish of the Pangasius genus, several Bettas (Betta spp.), 4 species of hillstream Loaches (Protomyzon spp.), and Tapah (Wallago maculatus). Also present is the endangered Asian arowana (Scleropages formosus).

Featured species

/ ©: WWF-Canon / Urs WOY
Asian bonytongue (Scleropages formosus) drawing.
© WWF-Canon / Urs WOY
Asian arowana (Scleropages formosus)

Asian arowanas grow up to 90 cm (35 in) total length. They have long bodies; large pectoral fins; dorsal and anal fins located far back on the body. These mouthbrooding carnivores have paired barbels on the end of the lower jaw.

Asian arowana scales are large and, in some species, metallic colored, with a distinctive network of raised ribs. They inhabit blackwater rivers, slow-moving waters flowing through forested swamps and wetlands. Adults are piscivorous, with juveniles feeding on insects.

All species of arowanas are paternal mouthbrooders. Slow to reach sexual maturity, they are difficult to breed in captivity. Asian arowanas are considered "lucky" fish by many people, particularly those from Asian cultures.

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Threats
Deforestation, conversion to agriculture, overfishing, exotics, the aquaculture industry, and mining pollution threaten these habitats and their native species. Proposed hydropower dams on high-gradient streams would jeopardize the natural flow regime and species movements.
WWF’s work

Tri-national commitment to leatherback turtle conservation in the Pacific
29 Aug 2006
Bali, Indonesia — Indonesia, Papua New Guinea and the Solomon Islands have agreed to protect the endangered leatherback turtle in the Pacific through joint conservation activities.

The tri-national partnership, supported by WWF, will allow the three countries to enhance conservation of leatherback turtles through information sharing, data exchange and cooperative research. It also plans to establish a network of marine protected areas covering critical leatherback habitats throughout parts of the western Pacific Ocean.

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Photos and graphics © WWF or used with permission. Text available under a Creative Commons licence.