Algal bloom leaves Coorong facing 'ecological collapse', advocates warn

Australia Broadcast Center

4 days ago

The internationally significant Coorong wetlands are at risk of becoming a "wasteland" due to the toxic algal bloom that is ravaging South Australia's coastal ecosystems, according to advocates who say the area is now at a "threshold" moment.
The shallow saline lagoon, which stretches roughly 130 kilometres along the state's south-east coast, has been dealing with a multitude of environmental pressures since the 1970s, with conservationists fearing this year's bloom will be "the straw that's broken the camel's back".
The state government is also "deeply concerned" about the Coorong's future, with Acting Premier Susan Close warning that the area has been "on the brink for a very long time".
But she cautioned that the extent to which the Karenia mikimotoi bloom will cause a permanent change to the Coorong's ecology is "not yet certain".
The toxic algae — which has been ravaging SA's marine life since March and disrupting fishing, aquaculture and tourism businesses — is believed to have entered the Coorong's North Lagoon at the end of May via the mouth of the River Murray.
It has since killed thousands of the Coorong's polychaete worms, crabs and fish.
"We're looking at an ecological collapse," said Dr Jonathan Sobels, chair of the Coorong Environmental Trust (CET).
"The likelihood of anybody being able to get a livelihood out of the Coorong as a fisherman is compromised.
"There's a significant threat to livelihoods and to the food chains that support a wide variety of plants, fish, microbes, little crustaceans, shellfish — the whole lot."
The Coorong, which formed the backdrop of Colin Thiele's classic Australian book Storm Boy, is also known as a breeding site for pelicans and migratory birds.
According to the Environment Department, the region supports 11 threatened species, six threatened migratory waterbird species and two threatened ecological communities.
There are now fears about what those migratory birds will eat given the widespread fish kills.
Commercial fisherman Garry Hera-Singh, who first started fishing in the Coorong in 1974, said he has seen smaller fish, crabs and marine worms "washing in by the acres".
"To me, the alarm bells are going off," he said.
Mr Hera-Singh, a third-generation fisher, said he has already advised his son, also a fisher, to "seriously … consider changing course and changing occupations if this bloom re-occurs".
The Coorong is listed as a wetland of international importance under the 1971 Ramsar Convention, an international treaty aimed at halting the loss of wetlands.
Dr Sobels, the CET chair, said the bloom's degradation could put the Coorong's Ramsar listing "in jeopardy".
"I wouldn't want to be the government that was known to be responsible for the loss of the significant international wetland," he said.
The federal government is responsible for nominating and conserving Australia's Ramsar-listed wetlands.
The Coorong was added to the list in 1985 — one of six Ramsar sites in SA and among more than 60 across Australia.
The ABC contacted Environment Minister Murray Watt for comment.
The Coorong is divided into a North and South Lagoon, with the latter suffering considerable environmental degradation since the 1980s.
This has been partly attributed to poor water management between the Murray Darling Basin states as well as the Millennium Drought, which saw River Murray flows drop to record lows over the 2000s.
Dr Sobels said the South Lagoon is "essentially a bacterial soup" and the North Lagoon is "now moving in the same direction" because of the bloom.
"So, the crisis is that the Coorong might end up being much more of a wasteland than it currently is," he said.
Estuarine ecologist Faith Coleman said Karenia's entry into the North Lagoon has caused "extensive deaths" in the "one truly healthy area of the Coorong that was remaining".
"It [the bloom] has been the straw that's broken the camel's back," she said.
"We previously had 20 to 30 per cent of the Coorong that was healthy, and that is the area that the Karenia bloom has hit.
"I believe that this Karenia bloom is the threshold that the South Lagoon went through in … the late '70s, where it went from that beauty to a septic pit."
The CET has put forward a four-point plan to address the issues in the Coorong, describing it as a "last-ditch attempt" to fix the issues in the North and South lagoons.
The plan includes keeping the salinity of the South Lagoon within a narrow range, maximising flows into the South Lagoon, operating water efficiently and using burnt lime to boost water health.
Ms Coleman, a founding member of the CET, said successive governments have failed to address the Coorong's decline despite millions in research funding.
Acting Premier and Environment Minister Susan Close said Ms Coleman presented the four-point plan to her "a couple of weeks ago".
"We're looking really favourably on all of the points that she's making," Dr Close said on Tuesday.
"We're working through the detail of how they can be enacted."
The acting premier said the state government was doing weekly algal testing in the Coorong.
She said the bloom was "yet another attack" on the Coorong, arguing the area has copped "a hell of a hammering over the last few decades because of the way that the Murray-Darling Basin has been treated by other states".
"Being able to flush the Coorong with freshwater at a time that helps the environment makes all the difference, and not having that has been a big problem."
The acting premier said while the government was "deeply concerned" about the Coorong, there were still "things that can be done".
She said the state government has investigated adding a clay that can deal with Karenia mikimotoi but was advised by scientists that it's "likely to cause more harm than good".
"We're looking at ways in which we can manage water in order to push the Coorong's salinity out of the comfort zone for Karenia mikimotoi," she said.
"But again, we don't want to flush too much because then the Karenia mikimotoi makes its way to the South Lagoon.
"The fact that we are still working through this does not mean that we are not paying very careful attention and getting all of the best scientific expertise on the case."