Murray Ruled Out Of Wetland's Woes

The Age

Wednesday November 30, 2005

MELISSA FYFE

IT APPEARS the Coorong - South Australia's wetland of world significance at the Murray River's mouth - does not work as people thought.

Long a "pin-up" for the Murray's woes, it was thought the Coorong was ailing because it lacked fresh water from Australia's greatest river.

But University of Adelaide research, to be presented at a Hobart conference today, reveals that for most of the Coorong's 6000 years, the Murray has had little influence.

A type of phytoplankton readily found in Murray River sediments is missing from those in the Coorong, leading senior lecturer Peter Gell and PhD student Deborah Haynes to conclude that the Coorong was probably fed by fresh water - now drained - from south-east South Australia, near the Victorian border.

The research has found that the Coorong - a long stretch of lagoons that support 238 bird species - is unhealthy because of a build-up of sediments and mud.

The wetland was now "plugged" at both ends, Dr Gell said. The eastern side no longer gets freshwater flows because it was drained for farmland.

The Murray mouth, on the other side, often closes over.

"It is now much more saline than it would have been in the past, and much more stable," Dr Gell said. "In the past, it would have got fresh water from the south-east of South Australia and sea water . . . The prevailing condition was a brackish-marine system."

But the Murray could still play a role in the Coorong's health, he said.

If greater flows could keep keep the Murray mouth open, salt water may be able to flush out the sediment choking the Coorong and hampering plant growth.

"The things that are holding the system together are gradually disappearing," he said. -- MELISSA FYFE