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Major freshwater ecosystem

Lowland and freshwater swamps are extensive along the south coast from the PNG international boundary to Etna Bay, in the southern lowlands of the Bird's Head, and along the north coast from the Mamberamo Delta westwards towards the head of Cendrawasih Bay.  Extensive inland swamps surround the Idenburg and Rouffaer rivers in the central depression of the Lakes-Plains province.  The swamps contain a diversity of habitats, including purely aquatic species, herbaceous vegetation, grass swamps, savannahs, woodlands and swamp forests.  Leersia, Phragmites, and Saccharum are dominant genera among the taller grasses, while Pseudorphis is a low-creeping form which characterizes extensive areas of grass swampland in the southeast.  Irian Jaya contains the world's largest resource of sago palms (Metroxylon sagu), which form extensive sago woodlands in shallow swamps that are well supplied with fresh incoming water.  Melaleuca woodlands characterize much of the seasonally inundated swamplands of southeast Irian Jaya in the monsoonal rainshadow, where they form even-canopied pure stands.  They are very fire-resistant and in many areas fire-scorched trunks from repeated burning scar much of the forest.  Pandanus, a widespread genus, also occurs in pure and mixed stands of woodland swamps in brackish and frequently flooded areas.  Other mixed swamp woodlands dominated by trees such as Carallia, Syzygium and Campnosperma are common in this environment and intergrade into rich swamps forests which are frequently dominated by the above species, or rare mixed with other trees such as Terminalia, Alstonia, Barringtonia, Metroxylon sagu, Diospyros, Pandanus and Myristica in deltaic region (Paijmans, 1976; Womersley, 1978).


This strict nature reserve contains 1,661,100 ha of uninterrupted array of habitat from the mangroves and swamps at the mouth of Mamberamo River up through the lowland forest and pristine montane zones of the Foja-Gauttier Mountain complex (2193 m) down through the lowlands and swamps of the Idenburg River system of Lakes-Plain region.  It contains the widest spectrum of mammals (100 species), and birds (330 species) north of the central cordillera.  It also contains Irian Jaya's largest lake, Lake Rombebai; the largest river, Mamberamo River; as well as mud volcanoes and hundreds of oxbow lakes.  With the wilderness area of the Foja Mountains as its centerpiece, a pristine mountain block where tree kangaroos and cuscuses can be closely approached.  There are no large population in the reserve.  The northern Mamberamo area has undergone petroleum exploration, and exploratory drilling development has taken place within the reserve boundaries.  Later, the area proposed to build a largest hydroelectric power plant and dam by BJ. Habibie, the former Minister of Research and Technology, but soon the proposal is denied due to political chaos and economic crisis in Indonesia.

See also Wasur National Park. [back to top]


New Guinea lies in the center of Indo-Pacific region, and along with the Malay Archipelago and the Philippines contains the richest and most diverse ichtyofauna of the whole region, estimated between 6000-7000 species (Munro, 1967; Carcasson, 1977).  This area has probably been the principal evolutionary center from which the entire Indo-Pacific region has been populated (Carcasson, 1977).

Allen and Cross (1982) have documented 158 fish species occur in New Guinea that are restricted to freshwater habitats and of these only 11 species occur on both sides of central cordillera, the major biogeographic barie of the island.  Among the interesting freshwater forms are the abundant and colorful rainbow fishes (Melanotaeniidae), a group that is confined to New Guinea and northern and eastern Australia.  These are widely distributed in streams, lakes, ponds and swamps and, because of their predilection for mosquito larvae, represent a possibility for small rural industry development.  An ichtyological survey of the Fly River identified 103 fish species, which are considered to be representative of the largely endemic and rich ichtyofauna that is uniformly distributed in the largest rivers of southern New Guinea, including the Lorentz and Digul among others in Irian Jaya (Roberts, 1978).  An extremely interesting characteristic of many species found in southern Irian Jaya rivers is the abundance of large-sized species, which is an unusual characteristic of other tropical ichtyofaunas elsewhere in the world (Roberts, 1978).  Sawfish (Pristiopsis) are the largest fish which frequent freshwater.  The Small-toothed Sawfish (Pristiopsis leichardti) of the large river systems of the north and south lowlands may reach 5.2 m and weight up to 450 kg (Roberts, 1978).  Some other interesting forms are the freshwater eels (Anguilidae) found in many streams, which spend most of their life in freshwater but migrate to the sea to spawn.  Jardine's Barramundi (Scleropages jardinii), permanent inhabitants of freshwater, are primitive herring-like fish with fossil forms dating back more than 75 millions years to the Eocene (Munro, 1967).  Curious archer fish (Toxotes) are well-known for their ability to 'shoot' insects by rising to the top of the water and expelling a drop of water from their mouth at the unsuspecting insects.  They have been found in southern rivers and lakes, the Bird's Head and some of the Raja Ampat Islands (Allen, 1978).  As most of the northern coastal rivers systems and the central part of the highlands have never been examined by ichtyologist, scientific research in the region is expected to make significant additions to our current incomplete knowledge of Irian Jaya's fish fauna.  (quoted from Petocz, R.G. 1987. Conservation and Development in Irian Jaya). [back to top]

Exotic Species

Exotic species in land and waters of Papua region is potential threat to the existence of native New Guinea species. To manage the threat, WWF Sahul Bioregion has established some assessments, monitoring and controlling activities to those exotic species.

Water Hyacinth

Water hyacinth started to manage in Merauke in 1990. Its fast growth and distribution makes water hyacinth to be important to manage. Water hyacinth distributes mostly in Southern part of Irian Jaya, from Timika to Papua New Guinea, Lake Sentani and surrounding area as well as Manokwari and Wamena in Jayawijaya district.

Management approach using physical, mechanical and biological has been established. Biological approach with bio-agent of Neochetina bruci flies. The flies released in Maro River of Merauke in 1995 and it has been successfully limited the population growth of the hyacinth. Also, the flies released in Sentani Lake in Jayapura district and showed positive improvement in several monitoring sites that the hyacinth is decrease significantly.

Training program in managing the water hyacinth has been conducted in Merauke on December 1998 and Timika on 8-11 February 2000.  Training involved many participants from local KSDA, national parks authority, private sectors, local people and NGOs.  PT Freeport Indonesia gave positive contribution and supports in conducting this program in Timika.  The participants is encouraged to be active in managing the hyacinth in their countryside as well.

During the training, participants trained to develop the breeding pool for Neochetina flies culture.  Before the training completed, the flies has been released as bio-agents for controlling the hyacinth. [back to top]

Mimosa Weeds

Mimosa weed (Mimosa pigra) is exotic plant from Latin America. Its distribution in Merauke has been identified in 1995, particularly Maro River of Poo village. 1998 survey showed that the distribution area reach to 7.8 hectares along the river bank. Some problems has been felt by local people, including the difficulty to set their net in the river bank. The most serious problem is fast growth and distribution that potentially threat the Wasur National Park, in particular the flood plain. Last, in August1999 Mimosa weed has been distributed to Wasur village. [back to top]

Exotic Species Observer Network of Irian Jaya

Jaringan Pemerhati Tumbuhan Eksotik Invasif di Irian Jaya (JPTEIJ) or Invasive Exotic Plant Species Observer Network in Irian Jaya founded in Merauke, Irian Jaya on 5 December 1998.  The network established to protect the native biodiversity and habitat in Irian Jaya.  The network take a position as bridge in managing the exotic species problems between the provincial government and NGO in Irian Jaya.


The existences of non-commercial exotic species in Irian Jaya, either intentionally or not, led to the change of environmental quality as well as threat the habitat. One of the exotic floral species that already bring impact is water hyacinth, in which its population is abundant and widely distributed in all over the province. In Maro River of Merauke for instance, there are huge number of water hyacinth cause the social, economic problems as well as threatening the preservation of native biodiversity and its habitat. Some impacts include river transportation disturbed, local people fishing yield decreased, such as high value fish of Arwana, shortage of water supply and river cleanliness.

The problem did not receive attention by the development program, because obstacles and limitations on the perception to the exotic species as well as the management approach. The network established to support and help the government in managing the problem to promote the environmental quality, native biodiversity and its habitat in the province from the exotic species threat.


Region I: Merauke and Timika Districts

Coordinator: WWF Sahul Bioregion-Wetland Sub Project, Merauke


Region II: Jayapura, Puncak Jaya, Wamena and Paniai Districts

Coordinator: Yayasan Lingkungan Hidup Irian Jaya/Irian Jaya Environmental Foundation (YALI), Jayapura


Region III: Manokwari, Biak, Serui, Nabire, Sorong and Fakfak Districts

Coordinator: Forestry Research Center (BPK), Manokwari


Information Center: WWF Sahul Bioregion - Wetland Sub Project, Merauke.

Duty and Responsibility

Information Center:

Regional Coordinator:



Region I

Additional Program:

Region II

Additional program:

a. Water Hyacinth

b. Stachytarpheta sp.

c. Mimosa weed (Mimosa diplotricha)

d. Siam weed (Chromolaena odorata)

Region III

Additional Program:


Nationally, there are Himpunan Ilmu Gulma Indonesia (Indonesian Weed Society) that can be partnered.

There are research centers, either national or international, such as Biotrop, CSIRO, Australian Natural Resources and Conservation.

Interest from international institution on the issue, including WWF Tropical Wetland of Oceania, that can be partnered.

Annual meeting, both Asian level or worldwide, in controlling the exotic species.

Workshop Recommendation

Based on the result of the Exotic Plant Species Workshop in Jayapura, Irian Jaya on 29-30 July 1999, the name of Jaringan Pemerhati Tumbuhan Eksotik di Irian Jaya (Exotic Plant Species Observer in Irian Jaya) has been changed to Jaringan Pemerhati Spesies Eksotik Invasif di Irian Jaya/ JPSEIIJ (Invasive Exotic Species Observer Network in Irian Jaya).

Annual Work Plan (October 1999-October 2000)

  1. Proposed Governor Decree will be followed up to implement through BAPEDALDA efforts

  2. Main issue of JPSEIIJ of the October 1999-October 2000 periode is integrated water hyacinth control

  3. Data formation on the distribution of water hyacinth in Irian Jaya will be established through either bureaucratic or non-formal approach using the legal format

  4. Work Plan October 1999- October 2000:

  1. Network member meeting will be held annually, while consolidation will be established every three months

Other Information

Water hyacinth established as the main issue of JPSEIIJ for the work plan October 1999-October 2000, however, there are eight other invasive exotic species in Irian Jaya. The limitation is due to the objective in providing full attention to the issue, so the water hyacinth could be managed more seriously. Network member still have opportunity to develop the control program to other species, such as Mimosa weed, Accacia nilotica, Siam weed, Long-tailed Macaque, Rusa Deer, Anabas testudines and Gobi fishes. [back to top]

Copyright 2000 Conservation Science Department WWF Indonesia - Sahul Bioregion