Air bubble curtains will be trialled to protect cuttlefish from South Australia’s toxic algal bloom killing marine wildlife and hurting costal businesses, the state government says.
A 200m x 100m bubble curtain is to be installed on the state’s Cuttlefish Coast in the Upper Spencer Gulf to protect 50,000-80,000 cuttlefish eggs and hatchlings.
Its installation at Point Lowly is expected to be complete this weekend.
The algal bloom is present on the western side of Spencer Gulf and moving north but has not arrived at Point Lowly, the government says.
ABOUT AIR BUBBLE CURTAINS
- The curtains create an underwater barrier of air bubbles that block the spread of algae.
- The bubbles are created by land generators and compressors which pump air through underwater feeder lines and tubing.
- This creates a buffer zone two metres to seven metres deep along the reef.
- These curtains have never before been used in South Australia.
- The curtain cannot work in areas where the algal bloom is already present.
- Bubble curtains have been successfully trialled in WA to protect kelp but there are limitations on their use (e.g. they cannot protect oysters from brevetoxins nor can they be used across large areas or in intertidal zones). Source: SA Government
The project is a state-federal initiative; Federal Environment Minister Murray Watt says both governments are leaving “no stone unturned” in combatting the state’s algal bloom.
“We are very hopeful the bubble curtain can make a difference during breeding season for the giant cuttlefish,” he says.
Watt says the plan builds on a priority assessment by the Threatened Species Scientific Committee which could trigger new conservation plans for any species under threat.
SA Premier Peter Malinauskas says their own scientific advisory panel told them that air bubble curtains are the best chance of protecting the species should the algal bloom reach the Cuttlefish Coast.
SA Environment Minister Susan Close says they are hopeful the technology will work but says government is also looking at other ways to restore the marine environments and protect species.
MP for Giles Eddie Hughes says the giant cuttlefish is “of special (economic) significance” to those who live in the Upper Spencer Gulf.
SA Primary Industry department executive director Professor Mike Steer says the bubble curtain is “another tool” to help protect marine species.
“By investing in science-based technologies such as this, we hope to protect those species we know could still be adversely impacted, particularly during egg development and hatching.”
The air bubble curtain will only be activated when the bloom is detected nearby at a time agreed to by cuttlefish and algae experts. The cuttlefish season has closed for the year.
Marine parks and harbour restrictions will apply through a 50-metre perimeter around the curtain, and the site will be monitored.
CUTTLEFISH SEASON
- Cuttlefish eggs start to hatch from late October to November.
- Dead cuttlefish are due to wash up on the coast at the end of their spawning season in coming weeks.
- Cuttlefish die after spawning as part of the natural cycle and the deaths cannot be blamed on the algal bloom.
- The latest giant cuttlefish count shows an estimated population at Cuttlefish Coast of 63,374 compared to 81,420 in 2024.
- The lowest population estimate was about 13,500 in 2013; the highest was 247,146 in 2020. Source: SA Government.
The government says parts of the state remain affected by the bloom (Karenia mikimotoi).
A marine heatwave (MHW) has been affecting southern Australia since September 2024 is believed to have fed the growth of the bloom.
The government says nothing can be done to dilute or dissipate the bloom but agencies continue to monitor it and take sample tests.
All national peak beaches are open but visitors should follow health advice on posted signs and avoid contact with discoloured or foamy water.
The government says the marine heatwave has cooled across the state’s coastal and gulf waters but temperatures that are 1 to 2 degrees Celsius warmer persist in deeper waters.
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