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Aquifers and caves

Aquifer and cave GDEs are dependent on the subterranean presence of groundwater (i.e. subterranean wetlands). Aquifer ecosystems are groundwater dependent and may provide suitable habitat for stygofauna (specialised groundwater fauna). 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]

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Amphipod, Photo by Moya Tomlinson

Quick facts

Stygofauna
refers to all aquatic fauna in groundwater. Very little is known about these specialised fauna including how many there are or what conditions they need to survive.

What are subterranean wetlands?

Isopod, Photo by Moya Tomlinson

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 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

Syncarid, Photo by Moya Tomlinson

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)

Terrestrial vegetation Photo by Moya Tomlinson

Linkages between subterranean wetlands and other ecosystems
Source: Moya Tomlinson

Riparian vegetation, Photo by DES

Seagrass, Photo by DES

Groundwater fed river, Photo by Nick Cuff

Subterranean wetland biodiversity

Diagram shows different types of fauna and where they live: <p>a. stygoxene</p><p> b. stygophiles</p><p> c. stygobites</p>

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).

 

Characteristics of subterranean ecosystems Ecological implications
Shared characteristics
Relatively stable environmental conditions compared with surface aquatic environments Buffered from environmental change taking place at the surface; habitat for relict lineages; fauna are morphologically conservative; selective pressure for cryptic speciation. Some species have restricted ability to respond rapidly to changes in groundwater regime or to recolonise readily after local extinction
Lightless No primary producers; heterotrophic microbes form the basis of food chain, providing ecosystem services; food web truncated, dominated by detritivores, with few predators, and herbivores represented only by root-mat feeders; a trophic shift towards omnivory
Restricted inputs of energy; low productivity Rate and timing of organic carbon supply determined by recharge pattern; fauna have slower metabolic rates, longer life cycles, lower fecundity than surface counterparts; overall faunal densities are usually very low
Characteristics that vary among subterranean aquatic ecosystems
Void size The void size determines available living space and groundwater flow rates
May be spatially discrete Restricted dispersal and recruitment; potential for speciation and short range endemism
May be connected to surface ecosystems Groundwater discharge may support surface ecosystems; recharge provides organic carbon and dissolved oxygen, and influences the groundwater regime
Subterranean beetle, Photo by Moya Tomlinson

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.

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, Elsevier, Academic Press, San Diego, pp. 383-383-397, <http://www.sciencedirect.com/science/book/9780123838322>.
  4. ^ Coineau, N 2000, 'Adaptations to interstitial groundwater life.', in H D Wilkens, C Culver & W F Humphreys (eds), Ecosystems of the World, Subterranean Ecosystems, Elsevier Amsterdam, pp. 189-189–210..
  5. ^ a b c EPA 2012, A review of subterranean fauna assessment in Western Australia DISCUSSION PAPER, Environmental Protection Authority, Perth, <http://edit.epa.wa.gov.au/EPADocLib/Disc%20paper%20OEPA%20subterranean%20fauna%20v2%200%20final%20Mar%202012.pdf>.
  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, no. 585, pp. 159-159–180, <http://palstrat.uni-graz.at/mitarbeiter/danielopol/189.pdf>.
  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

This page should be cited as:

Aquifers and caves , WetlandInfo 2013, Queensland Government, Queensland, viewed 11 February 2019, <https://wetlandinfo.des.qld.gov.au/wetlands/ecology/aquatic-ecosystems-natural/aquifers-caves/>.

Queensland Government
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