Surveys of groundwater invertebrate communities (stygofauna) have been required for pre-impact mining assessments for more than two decades, although the emphasis placed on their significance has varied through time and between States. Currently, all large developments in NSW, WA, and Queensland require stygofauna impact assessments to ensure that there are no long-term impacts. As large mines often have an impact on groundwater levels and water quality, if not appropriately managed, they represent a threat to stygofauna communities. This is particularly of concern where communities include species that are endemic to individual aquifers.
State-based survey guidelines, and the recently published Information Guidelines explanatory notes: Assessing groundwater dependent ecosystems (Doody et al. 2019), provide solid structures for conducting surveys, and in satisfying the necessary legislative requirements. Due to large amounts of uncertainty in the physical, chemical, biological, and hydrological factors that drive stygofauna distribution, many past surveys have lacked the scope and focus needed to maximise the intended purpose of understanding local or regional biodiversity.
Community and environmental data collected sporadically during stygofauna surveys in New South Wales over the past 20 years were analysed. Multivariate analyses (e.g. PERMANOVA, Bio-Env) were used to determine what hydrological or physico-chemical variables are the best indicators of stygofauna diversity. Univariate correlations were also made between taxonomic richness and key parameters.
Stygofauna richness correlates relatively poorly to any single variable, although depth to groundwater table is a major factor. Other key determinants include aquifer type, proximity to phreatophytic vegetation, and hydrological stability.