Living underground reduces the capacity of animals to disperse widely and both stygofauna and troglofauna (two types of subterranean fauna) tend to have much smaller ranges than equivalent surface species. The major conservation implication of these small ranges is that large-scale ground disturbance may sometimes threaten the persistence of a stygofauna or troglofauna species. In Western Australia, all native fauna are protected under the Wildlife Conservation Act 1950 and the environmental assessment process requires that the proponents of development proposals demonstrate that no species of stygofauna or troglofauna (subterranean fauna) are placed at risk of extinction.
Bennelongia has extensive experience undertaking field and desktop surveys of stygofauna and troglofauna for resource development. Subterranean fauna are sampled through suitable drill holes using nets and traps according to EPA Technical Guidance – Sampling methods for subterranean fauna here. The company operates a large laboratory with state of the art microscopes, photographic systems and extensive voucher collections for specialist invertebrate identification. Bennelongia undertakes stygofauna and troglofauna identifications for other consulting firms.
Stygofauna are aquatic animals that live in groundwater, often at considerable depths below the ground surface. While some of the best-known species occupy lakes in subterranean caves, most stygofauna species occur in alluvial, karstic or fractured rock aquifers. They occupy the interstitial spaces, vugs and fissures in these aquifers. Most stygofauna are invertebrate crustaceans but there are also stygal mites, worms, snails and beetles, as well as a few fish and amphibians. Because they live in the absence of light, stygofauna lack eyes and pigmentation. The Pilbara is a global hotspot for stygofauna, and their evolution and existence over millions of years is indicative of the longevity and importance of groundwater in the Pilbara environment.
Troglofauna, like stygofauna, are subterranean animals but they are air-breathing and are found from a metre of two below the surface down to the water table. Most troglofauna are invertebrates, with arachnid groups and primitive insects being well represented in troglofauna communities. Troglofauna are also eyeless and poorly pigmented. While troglofauna are mostly studied in caves, they undoubtedly occur widely in alluvium. They have also been collected from iron ore deposits and from calcrete beds in old valleys. Iron ore deposits develop many vugs and voids as they weather and these spaces provide troglofauna habitat. Calcrete also contains many voids.