Yoyo salt levels could mean the end for migratory shorebirds near the St Kilda mangroves

Adelaide’s internationally significant migratory shorebirds could be the latest casualty of the St Kilda mangrove salt disaster.

Adelaide’s internationally significant migratory shorebirds could be the latest casualty of the St Kilda mangrove salt disaster.

A scientific report has found their food – various invertebrate species – are being killed off by more than 19,000 tonnes of salt being pumped into the Dry Creek Saltfields system each week.

St Kilda Mangroves Alliance has released a report by saltfield ecologist Peri Coleman from Delta Environmental Consulting.

As well as blaming the salt discharge for mangrove deaths, Ms Coleman has identified “yoyo” salt levels as causing the deaths of invertebrate food for about 27,000 shorebirds that gather annually at the Adelaide International Bird Sanctuary, before their migration as far away as Alaska.

Thousands of migratory birds at the Adelaide International Bird Sanctuary, including sharp-tailed sandpipers, are preparing to return to the northern hemisphere. Picture: Chris Purnell

“Government graphs have shown from day one the system has never been able to hold a steady state of salt,” Ms Coleman said.

“There are a lot of animals which are tolerant of salt but they don’t like it changing by large amounts.

“This may well lead to birds leaving here underfed and maybe not making it to the northern hemisphere.”

The saltfields make up an area of about 50,000 house blocks in the bird sanctuary.

The fluctuations in ponds are sourced from state government reports which have monitored the saltfields since they were commercially closed in 2013.

Eastern curlews are a migratory shorebird which can be found at the Adelaide International Bird Sanctuary.

The saltfields again came under intense scrutiny when hypersaline discharge was blamed for a mass kill-off of mangroves at St Kilda.

The Advertiser has contacted the saltfield operator Buckland Dry Creek for comment. Ms Coleman said bird- counting teams had not been allowed in the area for two years, so there was no way of knowing what impact the lack of food was having on them.

The report also identified – for the first time – the huge levels of salt being pumped in seawater into the system, the discharge of which is blamed for mangrove deaths.

St Kilda Mangroves Alliance spokesman Craig Wilkins said it was clear from State Government data that the battle to maintain even salt levels had been lost two years ago.

“This lack of control is likely to have directly led to the mangrove deaths, with Buckland Dry Creek making increasingly risky choices to try to maintain the status quo,” he said.

“Even more alarming is the finding that this ticking time bomb is only getting worse.”