"In five to ten years the hypermarine south lagoon system will have changed to an estuarine system," said Dr Paton. "How will plants and animals respond? I expect lots of fresh water birds will be using it, but few hypermarine birds, and Ruppia gives us a clue to what will happen," he said.
Ruppia tuberosa grows around the lagoon edges in water between .3 to .8 metre deep. Dr Paton has taken plugs of the plant and placed them placed at intervals along the Coorong to mimic the salinity changes it will face.
"It does best if placed back where it came from," explained Dr Paton. "In lower salinity it does not do as well. In the north lagoon, which mimics what the salinity will be like if the drains go through, it grows fantastically but gets swamped by all the other things growing and never reproduces, so it disappears," he said. "The north lagoon has virtually no Ruppia; it has other species without turions which don't support birds."
Dr Paton has other examples of how the plants, animals and microorganisms of the southern lagoon will be affected by the drains. He believes that they are an inadequate solution to the problem that they are supposed to fix.
"If I were to deal with dryland salinity in the South East," said Dr Paton, "I 'd keep the problem where it is, not transfer it down the chain. Maybe we should trash one property to make storage for this water we are trying to get rid of," he said.
"The real problem is not salinity but vegetation clearance," he said. "We should be challenging whether we should be continuing to clearing."
"The solution is to use much more strategic revegetation to absorb the water before it gets into the ground water system," said Dr Paton, "To eliminate dryland salinity with a sustainable outcome instead of something that will continue to destroy natural assets."
Dr Paton's research will feature in a 30-part radio series on the Murray, to be broadcast on Radio 5UV in September.
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Contact: Dr David Paton
david.paton@adelaide.edu.au
618-83034742
Adelaide University
8-Apr-2001