Stygofauna in Australian Groundwater Systems: Extent of Knowledge

The extraction of coal and gas from coal seams often intersects aquifers with the potential consequence of changing the volume, quality, pressure and movement of groundwater. While such hydrological changes are well understood and can be modelled relatively accurately, the effects of these changes on the ecosystem that exists within aquifers are less well known and can be  challenging to predict.

Once considered devoid of life, aquifers in Australia and worldwide are increasingly being recognised for their biodiversity. The invertebrates inhabiting aquifers, commonly referred to as stygofauna, are diverse and are morphologically and physiologically different from even closely related surface-dwelling species. It is the unique invertebrate fauna that may be at risk from the effects of mining activities.  

'Stygofauna' as a term encompasses a variety of different types of organisms that are found in groundwater, and includes animals that are obligate, groundwater-adapted organisms (stygobionts), and those that are not specifically groundwater-adapted but are able to survive the harsh conditions in aquifers (stygoxenes). Stygofauna are dominated by crustaceans, but also includes beetles, snails, mites and a variety of worms, and include groups that are only found in groundwaters.

The deliverables of this project are:

· a desktop review of the state of knowledge and information available on the distribution and ecology of stygofauna in Australia and overseas;

· a preliminary identification of the potential hazards of dewatering on stygofauna;

· an examination of th regional water balances associated with groundwater use in major production regions;

· a survey of knowledge gaps, research priorities and recommendations for future research.

From the review of the literature and identified threats posed by mining and CSG activities, a number of knowledge-deficient issues were identified. These are:

· The effects of water level drawdown and depressurisation on stygofauna;

· The role of coal seams as stygofauna habitat;

· Water quality tolerance of stygofauna - toxicants and physico-chemical stressors;

· Groundwater foodwebs as a pathway to impact stygofauna;

· Taxonomy and distribution of stygofauna species; and

· Links between hydrological modelling and impacts on stygofauna.

In Summary:

· Research into the extent of knowledge of Stygofauna in Australian Groundwater was commissioned in September 2014 in response to increasing levels of stakeholder interest.

· The research reviewed current knowledge of Stygofauna distribution, life cycles, taxonomy, and potential interaction with mining, CSG and agriculture activities.

· Interaction with Groundwater Systems will vary with respect to location and activity, however, mining as a point source impact appears to present a reduced spatial extent, and associated likely lower potential impact level.

· The outcome of this project is a valuable introduction into this emerging environmental management aspect of the coal mining business.