A long-term study has found freshwater supply to Coorong mudflats is essential in stocking the ‘supermarkets’ for migratory birds to feed upon native invertebrates.
Icon Site Coordinator with the Department for Environment and Water Adrienne Rumbelow said migratory waders travel from the northern hemisphere to visit the Coorong between November and April every year.
“Like so many of us have found recently at our own supermarkets, the Coorong mudflats don’t always stock the food these birds need, and in some cases, there is no food at all,” she said.
“Researchers from Flinders University have been studying the health of Coorong mudflats for the last 15 years, including the different species of invertebrates in the area.”
Flinders University expert in coastal ecology Professor Sabine Dittmann said a healthy mudflat invertebrate community is well-stocked and has plenty of different types of aquatic invertebrates including worms, snails, crustaceans and insect larvae that live on or in the mud.
“Coorong invertebrates are sensitive to salt so if the water is too salty, many species cannot survive,” Professor Dittmann said.
“We have been finding a consistent pattern; the mudflats closest to the source of freshwater (near the Murray Mouth and barrages) are healthy and productive, with high numbers and a large variety of different invertebrates.
“But as you move further south along the Coorong and away from the freshwater, the numbers reduce to the point of ‘bare shelves’ in much of the Coorong South Lagoon.”
Ms Rumbelow said in recent years, water for the environment has helped deliver some freshwater to the Coorong, maintaining suitable habitat and food in parts of the Coorong North Lagoon. But after three straight years of dry conditions and low-flows, even the North Lagoon is beginning to struggle.
“Freshwater flows from the River Murray to the Coorong are vital for reducing salt and nutrient levels, which helps to support healthy mudflats and invertebrate populations,” she said.
“The $70 million Healthy Coorong, Healthy Basin project is jointly funded by the Australian and South Australian Governments and will develop and implement an action plan to help restore the Coorong’s health, characterised by healthy vegetation with abundant and diverse populations of waterbirds, fish and plants.”