Stygofauna are any fauna that live in groundwater systems or aquifers, such as caves, fissures and vugs. Stygofauna and troglofauna are the two types of subterranean fauna (based on life-history). Both are associated with subterranean environments – stygofauna are associated with water, and troglofauna with caves and spaces above the water table. Stygofauna can live within freshwater aquifers and within the pore spaces of limestone,

calcrete Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, ...

laterite Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by ...

, whilst larger animals can be found in cave waters and wells. Stygofaunal animals, like troglofauna, are divided into three groups based on their life history - stygophiles, stygoxenes, and stygobites. # Stygophiles inhabit both surface and subterranean aquatic environments, but are not necessarily restricted to either. # Stygoxenes are like stygophiles, except they are defined as accidental or occasional presence in subterranean waters. Stygophiles and stygoxenes may live for part of their lives in caves, but don't complete their life cycle in them. # Stygobites are obligate, or strictly subterranean, aquatic animals and complete their entire life in this environment. Extensive research of stygofauna has been undertaken in countries with ready access to caves and wells such as France, Slovenia, the US and, more recently,

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. Many species of stygofauna, particularly obligate stygobites, are endemic to specific regions or even individual caves. This makes them an important focus for the conservation of groundwater systems.

Diet and lifecycle

Stygofauna have adapted to the limited food supply and are extremely energy efficient. Stygofauna feed on plankton, bacteria, and plants found in streams. Orconectes australis (Marshal Hedin)

To survive in an environment where food is scarce and oxygen levels are low, stygofauna often have very low metabolism. As a result, stygofauna may live longer than other terrestrial species. For example, the

crayfish Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...

'' Orconectes australis'' from Shelta Cave in Alabama can reproduce at 100 years and live to 175. Antrobia culveri

Distribution and species

Stygofauna are found all over the world and include turbellarians,

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

s, isopods,

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

s, decapods, fishes, or salamanders. Stygofaunal gastropods are found in the U.S, Europe, Japan, and Australia. Stygobite turbellarians can be found in North America, Europe and Japan. Stygobite isopods, amphipods and decapods are found widely around the world. Cave salamanders are found in Europe and the U.S, but only some of these (such as the olm and Texas blind salamander) are entirely aquatic. The approximately 170 species of stygobite fish, popularly known as cavefish, are found in all continents, except Antarctica, but with major geographical differences in the species richness.

Collecting stygofauna

Several methods are currently used to sample stygofauna. The accepted method is to lower a haul net, which is a weighted plankton net (with minimum 50 µm mesh size), to the bottom of the bore, well or sinkhole and jiggled to agitate sediments at the base of the bore. The net is then slowly retrieved, filtering stygofauna out of the water column on the upward haul. A more destructive method is to pump bore water (using a Bou-Rouch pump) through a net on the surface (referred to as the Karaman-Chappuis method). These two methods provide animals for morphological and molecular analyses. A video camera can also be used down the hole, providing information on life-history of the organisms but, given the small size of the animals no species determinations can be made.

References

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External links

Italian groundwater AmphipodsOrigin and Age of the Marine Stygofauna of Lanzarote, Canary Islands
Freshwater animals Cave animals Ecology Hydrology

Diet and lifecycle

Distribution and species

Collecting stygofauna

See also

References

External links