Recommendation to the Minister for the Environment and Water Resources from the Threatened Species Scientific Committee (TSSC) on a public nomination for an ecological community listing on the Environment Protection and Biodiversity Conservation Act 1999 (the Act)
1. Generally accepted name
The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin
2. International/National Context
The Great Artesian Basin (GAB) lies within Queensland, New South Wales, South Australia and the Northern Territory. The GAB underlies about 22% of the Australian continent and is one of the largest artesian basins in the world.
Springs arising from the GAB occur within Queensland, New South Wales and South Australia.
3. How judged by TSSC in relation to the Environment Protection and Biodiversity Conservation Act 1999 criteria
The TSSC judges the ecological community to be eligible for listing as Endangered under the Environment Protection and Biodiversity Conservation Act 1999. The justification against the criteria is as follows:
Criterion 1 – Decline in geographic distribution
Excessive extraction of artesian groundwater from the Great Artesian Basin (GAB) has led to both the extinction of springs and a reduction in water flow of many of the remaining springs. The discharge rate of flowing artesian wells (bores) has declined considerably since the early 1900s. This is particularly pronounced within the Mulga Lands and Brigalow Belt South bioregions.
Active springs arising from the Queensland component of the GAB have declined to <10-30% of their original existence following the construction of bores for pastoralism in the late 1800s.
Despite the implementation of the State and Federal Government Great Artesian Bore Rehabilitation Program, ongoing extraction of artesian water is likely to play a continued role in the decline of these springs.
Therefore, the decline in artesian water pressure and the resultant degradation and extinction of spring communities means that The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin is eligible for listing as Vulnerable under this criterion.
Criterion 2 – Small geographic distribution coupled with demonstrable threat
Springs of the GAB are very restricted in their patch sizes, ranging from a few centimetres to approximately 100 metres in diameter. Individual springs may be isolated by tens of kilometres from the next nearest spring.
Existing and proposed threats include draw down of the waters of the GAB, grazing and trampling by livestock and feral animals, mechanical modification of structure (ie dam creation) and the introduction of exotic pasture species. The impact of these threatening processes within a particular timeframe is unknown, however, it is likely that their continuation and intensification may cause the extinction of many more springs in the near future.
Therefore, in view of the reduction in active springs across the GAB and ongoing threatening processes, The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin is eligible for listing as Endangered under this criterion.
Criterion 3 – Loss or decline of functionally important species
The nominations provide no information under this criterion.
Criterion 4 – Reduction in community integrity
The Great Artesian Bore Rehabilitation Program provided an incentive to landholders to encourage the rehabilitation of uncontrolled flowing artesian bores. The Commonwealth Government has made a commitment to further invest in these activities through the Great Artesian Basin Sustainability Initiative. It is hoped that the better management of artesian bores will increase the pressure of the artesian groundwater, removing one of the key threats to the survival of the artesian springs.
It is unclear the positive impact that these programs will have on the artesian springs, nor is it clear what the negative impact of other threatening processes may be in the longer term.
Criterion 5 – Rate of continuing detrimental change
The nominations provide no information under this criterion.
Criterion 6 – Quantitative analysis showing probability of extinction
The nominations provide no information under this criterion.
4. Conclusion
Under criterion 2, The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin is eligible for listing as an Endangered ecological community as it has a very restricted geographic distribution and is subject to threatening processes that could cause it to be lost in the near future.
5. Recommendation
The TSSC recommends that the nominations for:
- (2.10.8) Springs usually in sandstone valleys or at cliff bases and all spring fed ecosystems - Gulf Plains;
- (4.3.22) Mound springs arising from the Great Artesian Basin - Mitchell Grassland Plains;
- (6.3.23) Mound springs associated with the Great Artesian Basin discharge areas - Mulga Lands; and
- (5.3.23) Mound springs associated with the Great Artesian Basin discharge areas - Channel country.
be rejected as individual nominations. The TSSC further recommends that, the list referred to in section 181 of the Environment Protection and Biodiversity Conservation Act 1999 be amended by including in the list in the endangered category the ecological community as described at attachment (iii):
6. Attachment (i)
Summary description for the determination
The listing, The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin, includes springs within the GAB discharge area (see Figure 4, Great Artesian Basin Consultative Council, 2000) that are the natural surface discharge points of aquifers in the Triassic, Jurassic and Cretaceous sedimentary sequence of the Great Artesian Basin (Habermehl, 1982). Not included are those springs arising from Tertiary sediments and basalts.
Natural discharge from the Great Artesian Basin may occur as springs, mound springs, mud springs, boggomoss springs (see Noble, et al., 1998), spring pools or groundwater seeps.
Natural discharge springs mainly occur within twelve "spring groups" across the Basin (Habermehl and Lau, 1997). A number of these - the Cape York, Flinders River, Barcaldine, Springsure and Mulligan River groups - include some springs that arise from recharge rejection within the recharge areas of the Basin. These springs are not included in this determination.
The community is comprised of native species which depend on the natural discharge of groundwater from the Great Artesian Basin for their existence. The community is characterised by combinations of native species that may occur more widely than the GAB, as well as endemic species (restricted to one or more GAB spring). Not every species of the ecological community will be present at every spring.
Examples of such species include:
- Jardinella sp (endemic snail)
- Schoenoplectus pungens (flora species)
- Utricularia sp (aquatic forb)
- Cyperus gymnocaulos (flora species)
- Cyperus laevigatus (flora species)
- Eriocaulon carsonii (aquatic herb)
- Eucalyptus camaldulensis (flora species)
- Heliotropium curassavicum (flora species)
- Myoporum deserti (flora species)
- Sclerostegi sp. (flora species)
- Chlamydogobius sp (Elizabeth Springs goby)
Further species are documented in Wilson (1995) and Fensham (2000).