The occurrence of stygofauna in aquifers across the broad landscape has been studied intensively only during the last 25 years. Inventories have established that the Pilbara and Yilgarn regions of Western Australia comprise a global hotspot for stygofauna biodiversity, while recent surveys suggest that some invertebrate groups are also well represented as stygofauna in eastern Australia. In addition to having considerable physiological and biogeographic interest, stygofauna exemplify many of the challenges confronting biologists when putting ecological theory into practice. One of the most striking characteristics of stygofauna is the small range of many species. In relation to iron-ore mining in the Pilbara, de-watering of open cut mines may lead to extensive areas of groundwater drawdown that encompass the full ranges of some stygofauna species. Less is known about the potential impacts of coal seam gas mining but the large sizes of some production fields mean they may encompass the full ranges of a significant proportion of any stygofauna species occurring within them. Water supply borefields tapping into groundwater aquifers are nearly always located in areas containing stygofauna species but groundwater drawdowns associated with sustainable water supply are usually small compared with mine de-watering or coal seam gas extraction and water supply activities rarely affect stygofauna significantly at the species level. Critical issues in environmental assessment are determining species ranges, inferring the aquifers the species use and assessing the likelihood of groundwater drawdown detrimentally affecting persistence. Adequate sampling design and methods and integration with geological and information are critical to assessment.