Inland waterways brimming with invertebrates despite drying trend

Jun 26, 2014 by Kerry Faulkner
Aquatic invertebrates found ranged from beetles, damselflies and dragonflies. Pictured: blue skimmer dragonfly (Libellulidae>Orthetrum caledonicum) Credit: Bill & Mark Bell

The observations of the nation's early explorers have been used by ecologists investigating the survival of aquatic invertebrates in the waterways of Australia's arid interior.

The team of ecologists found a surprising number of species has survived over a 113-year period from 1895 to 2008 however the ancient waterholes could be indicators for assessing the impact of climate change on biodiversity in arid Australia.

Central Australia has experienced one of the most rapid rates of warming on the Australian continent with annual maximum temperatures recorded in Alice Springs increasing two degrees since 1900.

The project team was lead by Northern Territory Department of Land Resource Management water ecologist Jayne Brim-Box with statistical analysis by Murdoch University disturbance ecologist Karin Strehlow.

Dr Brim-Box led a survey of 16 sites in 2008 at small permanent spring fed streams and larger riverine pools in the remote Finke Gorge, Watarrka and West MacDonnel national parks, comparing the results to previous surveys undertaken at the same sites in either 1986 or 1994.

The most recent sampling involved six 20 second sweeps with long-handled 250-micron mesh nets, collecting samples from all available habitat types to maximise the number of species encountered.

In addition, were hand-picked with forceps from rocks and wood at the springs where water was only present as a thin flowing film. Physiochemical variables like conductivity, temperature and pH were recorded at each site in each of the three survey periods.

Desert invertebrates coping well 
A comparison of the data with the records of the 1894 Horn Expedition—Australia's first scientific expedition to the region—showed all taxa 113 years later, except for a small number of species. The largest number of aquatic invertebrates was beetles, dragonflies and damselflies.

Dr Strehlow who 'crunched the numbers' says that's good news for the ecology of the region.

"It is quiet surprising that we haven't lost more, so it really is an indication of how resilient some of these taxa are that they can persist and that would be because they have developed a lot of strategies to cope with that drying climate.

"The climate has changed a lot and the system is not what it used to be; thousands of years ago when the Finke River was big and flowing some species would have been more common but now literally we are talking about little pools of air where they are just hanging in there."

"We are finding the same thing here in WA with the aquatic invertebrates, as our wetlands are drying, especially in the Perth metropolitan area the invertebrates are persisting."

Explore further: Pilbara study uncovers unique fly community

More information: Brim-Box, J., Davis, J., Strehlow, K., McBurnie, G., Duguid, A., Brock, C., McConnell, K., Day, C., and Palmer, C. (2014). "Persistence of central Australian aquatic invertebrate communities." Marine and Freshwater Research 65, 562–572. dx.doi.org/10.1071/MF13131

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