Aquifers and caves

What are subterranean wetlands?

Subterranean wetlands include all underground areas containing water, including ice caves.  Australia supports a rich array of these subsurface aquatic environments ranging from the aquifers of the Great Artesian Basin to the karst system in Ida Bay, Tasmania[2] .

Subterranean wetlands include some coastal hypogean habitats which are influenced by the presence of seawater. These include anchialine caves (such as the Bundera Sinkhole in Cape Range Peninsula, Western Australia[9]), groundwater estuaries (seawater-groundwater interface[8]) and sea caves (littoral caves[7]).

The definition used in this section is based on the Interim Australian National Aquatic Ecosystem (ANAE) Classification Framework which includes 4 systems that have been identified in the subterranean class based on ecological principles rather than geomorphology:

• fractured
• porous sedimentary rock
• unconsolidated and
• cave/karst aquifer systems.
  

Subterranean wetlands do not include the endogean (edaphic) environment, which is the soil zone separating the soil surface (epigean) from the hypogean (subsurface saturated) environment[6].

The following definitions of aquifers taken from Tomlinson and Boulton (2008) provide additional clarity:

• Unconsolidated aquifers—Unconsolidated aquifers consist of particles of gravel, sand, silt or clay that are not bound by mineral cement, pressure or thermal alteration of the grain[6]. On a larger scale, alluvial aquifers represent an interstitial highway linking spatially discontinuous subterranean ecosystems with surface waters[11].
• Fractured rock aquifers—Fractured rock aquifers occur in rocks of sedimentary, igneous or metamorphic origin.

• Karst—karst is a term describing subterranean systems with a large void size. Karst is a terrain characterised by sinkholes, caves and springs developed most commonly in carbonate rocks where significant solution of the rock has occurred due to flowing water[1].

Subterranean wetlands are aquatic ecosystems

Aquifer ecosystems:

• have a diversity of habitats (sand, gravel, fractured rock, karst, calcrete)
• are home to a vast diversity of microorganisms, invertebrates and even some vertebrates
• deliver ecosystem services (breakdown of organic carbon, nitrate reduction, containment attenuation)
• support terrestrial and other aquatic ecosystems
• provide approximately 20% of water used in Australia
• are largely unresearched compared to other areas water management.

Ecological function in subterranean wetlands (aquatic ecosystems)

Subterranean wetland biodiversity

Typical subterranean wetland biodiversity often includes:

• a low number of genetic lineages—resulting in species which look dissimilar to related groups[5]
• high endemism—plants and animals that only live in one area or place e.g. a species that only lives one cave wetland[5]
• relict taxa e.g. from previous climatic conditions[5]
• phreatomorphies—groundwater adapted crustaceans belonging to different phyletic groups evolve convergently a suite of traits, called by Coineau[4], phreatomorphic characters when animals occupy interstitial habitats or troglomorphic traits for cavernous dwelling animals[3]e.g. smaller bodies or enhance sensory organs used to live in the dark.[10]

Subterranean fauna: stygofauna or trogofauna

Troglofauna are terrestrial, air-breathing fauna that do not rely directly on groundwater, although groundwater provides them with a humid environment and carries food from the surface. Stygofauna refer to all aquatic fauna in groundwater. Stygofauna can be classified depending on how much of the life cycle is spent in groundwater (see diagram).

What stygofauna can tell us

The presence or changes to stygofauna can be used to determine:

• surface water connectivity
• water quality
• the biodiversity, health and function of groundwater dependent ecosystems
• the effectiveness of water management strategies through collection of baseline data.

Wetland on-line education modules

A series of on-line education modules, including Groundwater dependent ecosystems, has been prepared as a resource for people who want to learn more about wetlands.

Users can download and use the contents of this education module to meet their learning and training needs. This information should be used in conjunction with information found on this website.

Additional links

• Queensland subterranean aquatic fauna database
• Nutrients and herbicides in groundwater flow to the Great Barrier Reef Lagoon—Report
• Australian Government groundwater publications
• National Groundwater Information System
• Dependence of Ecosystems on Groundwater and its Significance to Australia
• The National Centre for Groundwater Research and Training

Pages under this section

References

1. ^ Bakalowicz, M (2005), 'Karst groundwater: a challenge for new resources', Hydrogeology Journal, vol. 13, no. 1, pp. 148-160.
2. ^ a b Boulton, AJ, Dole-Olivier, MJ & Marmonier, P (March 2004), 'Effects of sample volume and taxonomic resolution on assessment of hyporheic assemblage composition sampled using a Bou-Rouch pump', Archiv für Hydrobiologie, vol. 159, no. 3, pp. 327-355.
3. ^ Christiansen, K (2005), 'Morphological adaptations', in D C White & W B White (eds), Encyclopedia of Caves. [online], Elsevier, Academic Press, San Diego, pp. 383-383-397. Available at: http://www.sciencedirect.com/science/book/9780123838322.
4. ^ Coineau, N (2000), 'Adaptations to interstitial groundwater life', in H Wilkens, D C Culver & W F Humphreys (eds), Ecosystems of the World 30: Subterranean Ecosystems, Elsevier, Amsterdam, pp. 189-210.
5. ^ a b c EPA (2012), A review of subterranean fauna assessment in Western Australia DISCUSSION PAPER. [online], Environmental Protection Authority, Perth. Available at: https://www.epa.wa.gov.au/policies-guidance/review-subterranean-fauna-assessment-western-australia-discussion-paper.
6. ^ a b Freeze, RA & Cherry, JA (1979), Groundwater, Prentice-Hall, Englewood Cliffs.
7. ^ Halliday, WR (April 2007), 'Pseudokarst in the 21(st) century', Journal of Cave and Karst Studies, vol. 69, no. 1, pp. 103-113.
8. ^ Hancock, PJ & Boulton, AJ (December 2005), 'The effects of an environmental flow release on water quality in the hyporheic zone of the Hunter River, Australia', Hydrobiologia, vol. 552, pp. 75-85.
9. ^ Humphreys, WF (1999), 'Physico-chemical profile and energy fixation in Bundera Sinkhole, an anchialine remiped habitat in north-western Australia', Journal of the Royal Society of Western Australia, vol. 82, pp. 89-98.
10. ^ Sanda, L, Namiotko, T & Danielopol, DL (2007), 'Evolutionary and taxonomic aspects within the species group Pseudocandona eremita (Vejdovsky´ ) (Ostracoda, Candonidae)', Hydrobiologia. [online], no. 585, pp. 159-159–180. Available at: https://www.researchgate.net/publication/225939879_Evolutionary_and_taxonomic_aspects_within_the_species_group_Pseudocandona_eremitaVejdovsky_Ostracoda_Candonidae.
11. ^ Ward, JV & Palmer, MA (July 1994), 'Distribution patterns of interstitial fresh-water meiofauna over a range of spatial scales, with emphasis on alluvial river aquifer systems', Hydrobiologia, vol. 287, no. 1, pp. 147-156.

Last updated: 22 February 2015