Yeelirrie stygofauna a step closer to extinction


This article from ABC News reports on the Commonwealth's approval of the Yeelirrie uranium project in Western Australia, an approval granted the day before the federal election was called.


Yeelirrie is the largest uranium deposit in Australia. The uranium is concentrated in a below-ground calcrete layer along a mostly dry palaeodrainage channel. Much of the uranium is below the water table.


Western Australia's Environment Protection Agency in 2016 recommended against approving the Yeelirrie project, mainly because the site has a rich and poorly understood community of stygofauna, invertebrates that live in groundwater aquifers. The Western Australian government in 2017 rejected that advice and approved the project, again just before an election (which the government then lost).


Stygofauna in Australia are taxonomically very poorly understood. Most species and many genera have not been resolved or named yet, making their study, conservation and documentation difficult. Stygofauna are usually sampled from caves, boreholes, drill holes and wells, and the full distributions of most species are not known. Many, however, almost certainly have very small ranges, often a single aquifer, making them highly vulnerable. Mining projects that destroy stygofauna habitat, either directly or by lowering water tables during mine dewatering or other operations, are likely to result in extinctions of species.


Stygofauna and troglofauna (species that live underground in spaces in rocks above the water table) have a remarkable evolutionary history. Some evolved from species that once lived on the moist floor of the rainforests that once covered much of now-arid Australia, evolving into underground forms as the rainforests died out. Others would originally have lived in the rivers that once flowed across the landscape (some of which were as big as today's Amazon), again evolving into species that specialised to live in subterranean groundwater as the rivers dried.


The loss of any of these species is a tragedy. With the loss of stygofauna we risk losing not only unique species and whole underground ecosystems, but also a remarkable link to Australia's distant past.

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