Killed and damaged mangroves at St Kilda, north of Adelaide, has the fear of ecological disaster rising in 2021
Killed and damaged mangroves at St Kilda on the coast north of Adelaide.
Images by Alex Mausolf and Chad Buchanan
Fears of an ecological disaster at coastal St Kilda north of Adelaide grew in 2021 with 10 hectares of nearby mangroves considered completely dead, along with 35 hectares of salt marsh, and researchers finding stressed, dying or dead vegetation in a 193 hectares area.
The St Kilda mangroves have died due to hypersaline water leaking into the surrounding marshlands. Hypersaline water had leaked through cracks in the pond's gypsum lining before seeping into the surrounding marshlands and mangroves — most nearly 150 years old.
In 2020, a salt mining company near the town of St Kilda reinstated a pump against the terms of its tenancy and filled dried-out gypsum ponds with hypersaline water. St Kilda township trees on the southern side of its Mangrove Street were among those impacted by the leakage with concerns the salinity could eat into the septic tanks and foundations of people's homes.
The department of energy and mining said the state government was working with the pond operators, Buckland Dry Creek, to “restore and maintain the stability of the site and allow for the right conditions for the rehabilitation of the impacted area. Analysis of piezometer data is showing positive progress but further monitoring is required to confirm that this pattern is maintained.”
The Environmental Protection Authority (EPA) installed groundwater testing instruments around the direct-kill zone of mangroves. St Kilda and Surrounds Development and Tourism Association president Lindsay Virgo says the pollution may have increased the already high salt levels in the area's soil to corrosive quantities.
Environmental consultant Peri Coleman the ponds should be capped and a hypersaline-tolerant plant community established on top of them. The plants would use the rainfall and prevent much of it from reaching the salt trapped under the soil.” A lot of pollution control is about managing the concentration and speed of the impact,” she said.
