High flows from the Murray to Korng are causing new wetland problems after years of low flows

Migratory birds from all over the world flock to the internationally important Coorong in South Australia made famous by the movie Storm Boy.

But scientists say the flooding of the Murray River has been “catastrophic” for bird species in the area, prompting urgent calls for better management and intervention of the river system.

Flooding has inundated the nesting sites of the area’s rarest and most vulnerable bird species, while algal blooms also limit the food source for migratory shorebirds that flock to the area near the Moray’s mouth to feed during the summer.

David Paton, an ecologist at the University of Adelaide, said the impact of the flooding could have been prevented.

“We’re probably sitting at a third of the numbers we counted last year, and that’s probably closer to a tenth of what it should be,” Dr. Patton told ABC News.

“This is a direct result of the rising water level.

Flood waters enter the Corong River.(hv news)

Very few birds that use Coorong don’t hold back and this adds another small nail in their coffin.

“There is not enough flow flowing in all the intervening years before these big floods that it protects them a little bit from the excessive flooding that is happening this year.”

High flows lead to algae blooms

Floods from the Murray River inundated more than 3,000 homes and properties in South Australia.

They also raise water levels in Coorong’s RAMSAR-protected wetlands and lakes, increasing nutrients in the water and reducing salinity.

“We now have algae blooms going on here,” said Dr. Patton.

“This is very disastrous if you are a migratory shorebird because you don’t have mud flats to feed in.

“The birds are now limited to the fact that they have to feast on the tops of this green filamentous algae which looks rather disgusting.”

Algae in Coorong.
Algae blooms in some sections of the southern lake in Corong.(ABC News: Claire Campbell)

Dr. Patton said there was no tracking of the birds to understand which ones had flocked to the now-flooded inland waterways, and which had just disappeared.

“We’ve never had egrets – and we counted the lakes south and north of the Korong,” said Dr Paton.

“We don’t actually know where the birds are right now if they’re not in Koreng.

“Species are slowly but surely slipping out of the system.”

Tern for the worse

The fairy tern is one of several species of birds that depend on the Coorong.

The numbers in South Corong Lake are believed to have decreased from 1,500 in the 1990s to about 300 today.

A flock of fairy terns in the air.
A flock of fairy tern flies over the corolla.(ABC News: Claire Campbell)

The usual nesting sites are underwater and ecologists managed to find only one nest this year in the southern lake, with the eggs at risk of flooding.

Ecologist Fiona Patton — David’s daughter — said she didn’t believe that many, if any, fairy tern chicks would hatch this season.

A change in the direction of the winds, storms, or an increase in the water level will be enough to drown them [eggs]She said.

“At the same time, any drop in water levels is also a risk because it will reconnect with the mainland and then the foxes will be able to get out and get ahead of the eggs or chicks at that point.”

An ecologist counting bird eggs at Coorong.
Ecologist Fiona Patton counts the eggs in a nest of fairy tern in Coorong.(ABC News: Claire Campbell)

Swansong for seaweed?

But like any natural event, there are winners and losers.

Pelicans and pelicans are expected to thrive as water levels rise.

Estuarine ecologist Faith Coleman said seagrasses—including a stonecrop unique to Corong—were also thriving.

Many black swans swim in the water between the sand dunes
Black swans on the Corong River.(hv news)

Dr. Coleman has been observing the aquatic life of nearby Salt Creek, which flows into South Lake.

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