Marine experts reveal what natural causes will slow spread of devastating algae bloom

South Australia's toxic algae bloom is spreading 2.5km daily across both gulfs, with experts warning it could take five years for marine life to recover.

The toxic algae bloom decimating the state’s ocean is spreading across the ocean like a “moving beast”, with marine experts fearing authorities are helpless to slow it down.

Latest satellite imagery shows levels of chlorophyll-a, which can indicate the presence of the toxic algae, are spreading by 2.5km a day across SA.

Dead marine life along the Ardrossan coastline in the Yorke Peninsula. Picture Ben Clark

The most recent figures show there are increased levels across the majority of The Gulf of St Vincent, from Troubridge Island on the Yorke Peninsula to Cape Jervis on the Fleurieu Peninsula.

It has also been detected in the Spencer Gulf, along the eastern coastline from Hardwicke Bay to Port Broughton, and on the western coastline from Tumby Bay to Lucky Bay.

Professor Mike Steer said the proliferation of the bloom was dependent on water temperature, nutrient levels and sunlight.. Picture: Supplied

South Australian Research and Development Institute Professor Mike Steer said the proliferation of the bloom was dependent on water temperature, nutrient levels and sunlight.

“Those three things are going to contribute to the population growing, reproducing, increasing,” Prof Steer said.

“You turn some of those off, then it will start dying, crushing, reducing.

“We’re seeing as we would expect in this bloom that’s pulsating, as part of its biology, it responds very quickly and agilely to a changing environment.”

The waters off Edithburgh on the Yorke Peninsula have been devastated by the algal bloom. Picture: Great Southern Reef Foundation.

Prof Steer was hopeful a dip in water temperatures would help to curb the bloom, which has devastated the fishing and tourism industries across the state.

“We’re tracking the temperature and we’re seeing that as you would expect in winter, the temperature is starting to decline in the gulf waters,” he said.

“So seeing those temperatures go down is something that we are happy to see.”

But other experts were not as optimistic, fearing it could be years before SA’s marine life was back on its feet.

University of Adelaide marine scientist Dr Nina Wootton said the bloom was a “moving beast” that could get worse as water temperatures rise in summer.

“We still don’t really know if the winds change or the currents move if that rate could slow down or also go the other way,” she said.

University of Adelaide PhD candidate Nina Wootton in the Gillanders Aquatic Ecology Lab with king George whiting she used to research microplastics in fish. Picture: Tom Huntley

“We just have to hope that our ecosystem is resilient enough in certain ways that it will be able to get back from this - that is the only hope we have.

“We just have to cross our fingers and toes and wait it out.

“It will start to flourish again in warmer waters, even if it starts to drop off a little bit.”

She said it could take three to five years for SA’s marine to bounce back from the bloom.