Satellite images reveal shocking spread of South Australia’s algal bloom crisis

New space imagery reveals South Australia's algal bloom has spread across 4500sq km of ocean as international experts race to contain the crisis.

Exclusive: New images captured from space have revealed the extent of the devastating outbreak of South Australia’s algal bloom crisis as it dramatically spread.

The images from United States ocean science researchers taken between early February and last week map how the outbreak of karenia mikimotoi started as a small cluster that quickly spread across more than 4500 square kilometres in a thick mass.

Photo taken in 2014 at the Glenelg diving site The Dredge. Picture: Mark Tozer

Photo taken on August 10, 2025 showing the impact of the algae outbreak on the Glenelg diving site The Dredge. Picture: Mark Tozer

It comes as Prime Minister Anthony Albanese is scheduled to arrive in Adelaide to be briefed on the growing crisis on Wednesday.

The data was captured by the European Space Agency’s Copernicus Sentinel-3 satellite and processed by the United States National Oceanic and Atmospheric Administration’s National Centre for Coastal Ocean Science (NCCOS).

The spread of South Australia's algal bloom outbreak captured from space in February 2025.

Then in August. Pictures: Processed by NOAA National Centers for Coastal Ocean Science

Florida-based ocean scientist Charles Jacoby has studied algal blooms for more than 40 years and spent more than a decade of his career working in the waters off Australia and New Zealand.

A member of Florida’s Harmful Algal Bloom Red Tide Taskforce, Dr Jacoby said there were efforts in the US to replicate the success of mitigation efforts in China where clay is dumped into the affected areas, causing the bloom cells to cling to the particles and sink.

It’s a method another United States-based algal bloom expert Donald Anderson will discuss with Australian authorities during a trip to Adelaide this week.

Dr Jacoby warned completely eliminating algal blooms was “probably not in the cards”.

But he noted all algae was not necessarily bad and reiterated their importance for sustaining marine life.

“So you don’t really want to get rid of blooms,” he said.

“You probably want to keep from making them worse, which is something that human activities can do, and perhaps come up with control methods for particularly sensitive areas or species or whatever it might be.”

Algal blooms and large numbers of dead fish were found in the River Torrens near the Adelaide Zoo.

Dead marine life at Seacliff Beach as a result of the Algae Bloom. Picture: Tim Joy

Dr Jacoby said in Florida, where there are regular outbreaks of karenia mikimotoi’s more toxic cousin karenia brevis, authorities now monitor for blooms around the clock.

The blooms tend to happen mostly towards toward summer, not necessarily directly in summer, but about every year,” he said.

“About every year the red tide blooms form offshore, much like they’re talking about in South Australia.

“And then they often get carried inshore and obviously that’s when the issues really begin to ramp up.”

Local Chris Iwanicai looks at dead sea life caused by the toxic algae washed up along Seacliff Beach in August 2025. Picture: Mark Brake

Dead fish at Moana Beach as a result of the Algae Bloom. Picture: Picture: Tim Joy

Asked about anecdotal reports harmful algal blooms were getting more frequent and prolonged, he said it was difficult to say but said they were certainly noticed more now than they were in decades gone by due to increases in human activity in affected areas.

“In a sense (harmful algal blooms are) part of the natural cycles that you know will be there and it’s not necessarily totally driven by human activity, but that human activity can potentially make it worse,” Dr Jacoby said.

Originally published as Satellite images reveal shocking spread of South Australia’s algal bloom crisis