Arafura Swamp
The Arafura Swamp is one of Australia’s largest freshwater wetlands, located in the Arnhem Land region of the Northern Territory. Spanning approximately 300 square miles (777 square kilometers), it can expand to 500 square miles (1,295 square kilometers) during the wet season. Recognized for its ecological significance, the swamp supports a rich variety of biodiversity, including numerous endangered species, and is of cultural importance to the indigenous Yolngu people. The wetland features diverse habitats, such as grasslands, woodlands, and unique monsoon rainforests, and is characterized by its perennial water sources and lack of a continuous river channel to the Arafura Sea.
The Arafura Swamp has been designated as an Important Bird Area, providing vital breeding and refuge for various waterbird species, including the critically endangered hooded parrot. The region faces environmental threats from invasive species, climate change, and poorly managed fire regimes, prompting conservation efforts that often involve collaboration with the traditional Aboriginal landowners. As an Indigenous Protected Area, the swamp is managed using traditional practices, highlighting the importance of cultural perspectives in ecological preservation.
Arafura Swamp
- Category: Inland Aquatic Biomes.
- Geographic Location: Australia.
- Summary: One of Australia's largest freshwater wetlands, the Arafura Swamp is among the most undisturbed ecosystems in the world.
The Arafura Swamp is a large freshwater wetland situated at the northern coast of the Arnhem Land region in the Northern Territory of Australia. This biodiverse and virtually undisturbed tropical floodplain is home to a wide variety of species, some of which are endangered or vulnerable. The Arafura Swamp is an ecologically and culturally important region to the indigenous Yolngu people. In addition to monitoring the situation of threatened species, conservation efforts have centered on the negative effects caused by fires, feral species, weeds, and the intrusion of saltwater. Australia lists the Arafura Swamp as a wetland of national significance.
Occupying the expansive floodplain of the Goyder–Glyde river system in the Top End of Australia's Northern Territory, and adjoining the coastal plain and tidal waterways of Castlereagh Bay to the north, the pristine Arafura Swamp spans an area of some 300 square miles (777 square kilometers) in Arnhem Land, expanding up to 500 square miles (1,295 square kilometers) by the end of the wet season. It is the largest freshwater basin in East Arnhem Land, one of the largest wooded swamps in the Northern Territory, and one of the most undisturbed ecosystems in the world. Vast, open, and mostly inaccessible, the Arafura receives surface-water inflow from, and provides a flood-control basin for, the Goyder and Gulbuwangay rivers. Additionally, it is fed from below by the numerous springs that line the Goyder River. The water disperses through an irregularly shaped floodplain, discharging northward through the saline flats of the tidally affected Glyde River before emptying into the Arafura Sea through Castlereagh Bay along the northern coast.
Unlike other large coastal swamps in the Northern Territory that open up at their downstream limit toward the coast, the Arafura Swamp is surrounded by a low plateau that rises in parts to 300 feet (91 meters), dominated by scarps to the east and west. It is believed that this bedrock, which constricts the swamp at the northern end, forms a partial barrier preventing the influx of tidal water, creating Arafura's uniquely demarcated wetland basin. In the Top End, the Arafura Swamp is also unique because of the perennial inflow from the springs that line the Goyder River, as well as its lack of a continuous river channel to the Arafura Sea—conditions that result in some portion of the basin being flooded at all times throughout the year. The region has a tropical savanna climate, with average annual precipitation of more than 40 inches (102 centimeters). Rain falls primarily from December to April.
Biodiversity
The Arafura represents a complex, variegated network of landforms and wetland habitats, including virtually undisturbed grasslands, woodlands, coastal plains, sandstone hills, billabongs, lagoons, sinkholes, and drainage channels. Scattered along the edges of the basin are some 7,413 acres (3,000 hectares) of monsoon rainforest that have remained undisturbed by buffalo or pigs. Featuring a wide array of grasses, herbs, sedges, aquatic plants, trees, and floating mat communities, the swamp is dominated by two paperbark species: Melaleuca cajuputi and M. leucadendra, constituting Australia's largest contiguous forest of Melaleuca, a genus of the myrtle family primarily endemic to Australia and commonly known as paperbark because it sheds its bark in flat, paper-like sheets.
Several rare and notable examples of flora thrive in the Arafura Swamp, such as the Capentaria palm (Carpentaria acuminata); the rare talipot palm (Corypha elata); the fan palm (Livistona rigida); the commelinid Hanguana malayana, uncommon to other wetlands; the taro (Colocasia esculenta); and almost the entire Northern Territory population of the large and imposing Gebang Palm (Corypha utan), known for its spectacular inflorescence, which features up to one million individual flowers. The swamp is also home to at least two endangered plant species: the Australian arenga palm (Arenga australasica) and Freycinetia percostata.
The Arafura supports diverse fauna, including more than 50 plant and five vertebrate species endemic to the Northern Territory, and three recorded plant species known only to the Arnhem Coast within the Northern Territory, though they are also found in other Australian states. As of 2019, the swamp is home to twenty-seven nationally known or predicted threatened animal species including the partridge pigeon (Geophaps smithii), Merten's water monitor (Varanus mertensi), and yellow-spotted monitor (Varanus panoptes), all of which are classified as vulnerable; and the critically endangered Northern quoll (Dasyurus hallucatus), a native carnivorous marsupial. The only significant breeding population of the endangered hooded parrot outside the Katherine area lives in land adjacent to the swamp. The threadfin rainbowfish (Iriatherina werneri), once known only from the Cape York Peninsula in Queensland and in neighboring New Guinea, has been discovered in the Arafura.
Bird Species
A total of 17 migratory species recorded from the Arafura Swamp are protected under bilateral agreements or international conventions. Classified as an Important Bird Area by the Australian government, the Arafura Swamp supports abundant populations, including the red-collared lorikeet (Trichoglossus rubritorquis); the brown honeyeater (Lichmera indistincta); the silver-crowned friarbird (Philemon argenticeps); the white-bellied cuckoo-shrike (Coracina papuensis); and Australia's smallest bird, the weebill (Smicrornis brevirostris).
The wetlands are also an important refuge and breeding ground for significant populations of several species of waterbirds, most commonly the magpie goose (Anseranas semipalmata) and various egret species (Egretta). Other waterbirds found in substantial numbers are the green pygmy goose (Nettapus pulchellus), the Pacific black duck (Anas superciliosa), the little black cormorant (Phalacrocorax sulcirostris), the glossy ibis (Plegadis falcinellus), the Australian white ibis (Threskiornis molucca), the straw-necked ibis (Threskiornis spinicollis), the brolga (Grus rubicunda), the radjah shelduck (Tadorna radjah), the royal spoonbill (Platalea regia), the Australian wandering whistling duck (Dendrocygna arcuata australis), and darters (Anhingidae).
Reptile and Mammalian Species
Reptiles include the freshwater crocodile (Crocodylus johnstoni) and saltwater crocodiles (Crocodylus porosus).
Mammalian species include the brushtail possum (Trichosurus vulpecula), the northern brown bandicoot (Isoodon macrourus), the agile wallaby (Macropus agilis), and the delicate mouse (Pseudomys delicatulus). The area is also home to a significant number of two species of bats of the genus Pteropus (also known as fruit bats or flying foxes), which roost and feed in the Melaleuca forests: the little red flying fox (P. scapulatus) and the black flying fox (P. alecto).
Environmental Threats
Listed on the Register of the National Estate and part of the Arnhem Land Aboriginal Land Trust, the Arafura Swamp is Aboriginal freehold land, one of the few remaining tropical wetlands managed by Aboriginal peoples who employ traditional land management methods such as forest burning regimes. In 2019, the Australian government that Arafura Swamp would become an Indigenous Protected Area. (IPA). The swamp is one of seven newly proposed IPAs. The titles designates the area as a place where the traditional owners, the Indigenous people, work to protect the biodiversity and resources of the area. IPAs are recognized for their effectiveness and an important component of Australia’s efforts to preserve lands and protected areas.
Though it is one of the most undisturbed wetlands in Australia, the Arafura Swamp is threatened on several fronts. The ecological effects of grazing buffalo; the spread of weeds and invasive exotic pasture grasses; the recent arrivals of feral pigs, feral cats, and cane toads (a poisonous amphibian that has killed many endangered northern quoll); poorly planned fire regimes; and saltwater intrusion due to the effects of climate change have all been causes of concern for conservationists, some of whom have partnered with the Aboriginal peoples to develop sustainable land management policies.
Bibliography
"Arnhem Land, Northern Territory." Odyssey Traveller, 25 June 2020, www.odysseytraveller.com/articles/arnhem-land-northern-territory/. Accessed 28 Oct. 2024.
Brennan, Kim, et al. Biological Inventory of the Arafura Swamp and Catchment. Department of Infrastructure, Planning and Environment, 2003.
Brocklehurst, P. S., and B. A. Brocklehurst. Vegetation Communities of Arafura Swamp. Conservation Commission of the Northern Territory, 1996.
Campion, Otto Bulmaniya, et al. “Monitoring and Evaluation of Indigenous Land and Sea Management: An Indigenous-Led Approach in the Arafura Swamp, Northern Australia.” Ecological Management and Restoration, vol. 24, no. 2-3, 14 Dec. 2023, doi.org/10.1111/emr.12586. Accessed 28 Oct. 2024.
Chatto, R. The Distribution and Status of Waterbirds around the Coast and Coastal Wetlands of the Northern Territory—Technical Report 76. Parks and Wildlife Commission of the Northern Territory, 2006.
A Directory of Important Wetlands in Australia. Australian Nature Conservation Agency, 1996.