Lake Jasper / Gingilup-Jasper wetland system
Lake Jasper is the largest (440 ha) freshwater lake in South Western Australia, and along with Lake Smith and Lake Wilson forms part of an important wetland system known as the Gingilup-Jasper Wetland System. This wetland system is located on the Scott Coastal Plain, within the D’Entrecasteaux National Park and Gingilup Swamps Nature Reserve 30626 and comprises all wetlands on the coastal plain between the Donnelly and Scott Rivers, notably Lake Jasper and associated swamps Lake Wilson and Lake Smith (2 km east south-east), Quitjup Lake and associated swamps (5 km west north-west) and Gingilup Swamps (14 km west north-west; includes two small lakes). Most of this area is under water in winter. The system receives some inflow from creeks originating 3-15 km north north- east in partly cleared lowland. These become poorly defined as they reach the floodplain. However most supply, especially for Lake Jasper, is probably from groundwater.
Biological and physical values
Lake Jasper is a pristine lake known as a ‘white water lake’ due to the lack of tannic acid in the water, which results in good light dispersion and clear water. It is situated amongst vegetated dunes and fed by an underground water supply.
The lake supports an extensive area of tall sedgelands and is an important wetland for frogs, birds, fish and invertebrates.
Each winter the lowlands flood which means that the lakes can be linked, which is vital for the linking of biotic communities.
The system is effectively a `biological reservoir’ for native freshwater fishes, including seven of the eight species endemic to south-western Australia, because the wetlands are largely isolated from influences that commonly degrade water quality and from major river systems that contain or are likely to contain exotic species.
Lake Jasper is a major nursery area for native freshwater fishes and seven of the nine fishes known from Gingilup-Jasper Wetland System occur at Lake Jasper, including freshwater cobbler (Tandanus bostocki) , the western mud minnow (Galaxiella munda) and the western minnow (Galaxias occidentalis).
Lake Jasper is recognised as one of the five most important wetlands for waterbirds across the south coast; based on rankings of number of species, breeding pairs and number of individuals (Jaensch 1992a). Lake Jasper has been found to support the highest number of bird species found breeding at any one wetland across the south coast. During a survey of the Jasper Wetland System, 27 species of birds were recorded, including seven breeding species such as the Little bittern (Ixobrychus minutus) and the Australasian bittern (Botaurus poiciloptilus). Three of the species recorded are listed under international treaties. The most abundant species in the Jasper Wetland System was the little black cormorant (Phalacrocorax sulcirostris) (up to 200 on Lake Jasper).
Substantial areas of sedgeland and shrubland/forest, such as those present at Lake Jasper, support the highest number of the wetland frog species of the south coast of Western Australia.The Jasper Wetland System supports eight species of frogs; all have been recorded at Lake Jasper and a range from three to five species were recorded at the other lakes within the system. The number of invertebrate taxa recorded at Lake Jasper is 22.
Lake Jasper is also of particular archaeological and cultural significance to Aboriginal people. Numerous Aboriginal stone artefacts occur on the lakebed amongst numerous tree and grasstree stumps up to 10 metres below current surface levels.
Current Condition and Trends
The Gingilup-Jasper wetland system is identified as being ‘nationally important’ in the Directory of Important Wetlands in Australia due to meeting the criteria of:
- It is a good example of a wetland type occurring within a biogeographic region in Australia.
- It is a wetland which plays an important ecological or hydrological role in the natural functioning of a major wetland system/complex.
- It is a wetland which is important as the habitat for animal taxa at a vulnerable stage in their life cycles, or provides a refuge when adverse conditions such as drought prevail.
- The wetland is of outstanding historical or cultural significance.
It is described as an outstanding example of a near-pristine, extensive system of freshwater lakes, marshes and shrub swamps including the deepest, large freshwater lake in south-western Australia (Lake Jasper).
Nutrient enrichment within the catchment due to a rapidly developing horticultural industry, developing dairy industries, groundwater extraction, power-boat usage, exotic fish species and mining (mineral sands) pose a threat to the water quality of the Jasper Wetland System. The Gingilup-Jasper wetlands have been identified as having a high risk of salinity (Short and McConnell 2000).
The deeper South West Yarragadee aquifer is the largest freshwater aquifer in the south-west, and although partly used for agricultural irrigation, it has been investigated as an additional source of freshwater for the south-west. Any future use may impact on groundwater dependent ecological communities such as the Lake Jasper wetlands and would require detailed assessment.
Threats to the waterbirds in the parks include wildfire, proposed mineral sand mining and recreational use of waterbodies disturbing birds during the breeding or moulting seasons. The main threats to the Australasian bittern are salinisation or drainage of wetlands as they have narrow habitat preferences and are more sensitive to overall habitat loss than many other wetland species. Inappropriate fire regimes, which destroy fringing vegetation, can also reduce habitat suitability (Marchant and Higgins 1990).
In 1994, 368 hectares of land in the Lake Jasper area was excised from D’Entrecasteaux National Park and along with 32 hectares of private property a section 5(1)(g) reserve with the purpose of ‘conservation and mining’ was created to facilitate mining (see Section 32 Mining). Part of the northern part of the section 5(1)(g) reserve has already been mined and rehabilitated and is to be returned to D’Entrecasteaux National Park. Cable Sands indicated in mid-2010 that it will not be proceeding with mining in the remainder of the section 5(1)(g) reserve. Therefore it is to be returned to D’Entrecasteaux National Park, and most of the adjoining CALM Executive Body property will be returned to Cable Sands. The department is negotiating to establish a buffer area located to the north and north-west of Lake Jasper to be incorporated into the park because it contains important wetland habitat and vegetated areas. A new mining tenement has been established over the area.
Gingilup-Jasper wetland system and Climate Change
Predicted level of risk due to:
Decreasing rainfall – low
Increasing temperature – very low
SWCC Strategic Priority
Lake Jasper / Gingilup-Jasper wetland system is identified within SWCC’s NRM Strategy as a first order priority asset under both the Aquatic Biodiversity and Water Resources themes.
- Shannon and D’Entrecasteaux National Parks Management Plan (2012). Department of Parks and Wildlife.