SA diver shocked by the impacts of algal bloom on SA coastlines, but experts say glowing red algae is a promising sign

A seasoned diver has compared the algal bloom crisis off SA coastlines to Chernobyl with his underwater images highlighting the depths of the natural disaster.

A fisherman whose family have been fishing SA’s coastline for six generations says he’s never seen the marine industry so devastated, as a new red algae offers a reprieve from the toxic algal bloom.

Nathan Eatts is a squid fisherman operating out of Cape Jervis on the Fleurieu Peninsula.

He told The Advertiser he hasn’t managed to hook a squid since Good Friday more than two months ago, and is nearly out of stock in his coldroom, leaving him without a source of income.

“It’s devastating,” Mr Eatts said.

“I sort of gave up trying a bit there for a while, just going out once or twice a week.”

“You get a pretty good idea pretty quick when there’s nothing around.”

Mr Eatts operates slightly differently to many of his fellow fishermen, also doing his own processing.

He said instead of sending all his catch to market at once, he puts his squid in a coldroom, so he has been able to keep a steady income slowly selling his stock, which is now starting to run low.

“In the next few weeks I’m going to be completely out,” he said.

“I’m lucky enough that I sell directly to restaurants so I just sell it in dribs and drabs.”

“I’m getting to the bottom of my stockpile now.”

Mr Eatts said he was concerned for the long term impact the bloom may have on his business.

Squid fisherman Nathan Eatts hasn’t caught a squid since Good Friday due to the toxic algal bloom. Picture: Roy VanDerVegt

“It’s not a nice feeling at all, we’ll try and brave it out for as long as we can, but it’s going to get to the point where we’re going to have to try and find another job.”

Despite the direness expressed by many fishermen about the devastating effects of the algal bloom, hope could be on the horizon for SA’s marine life – with a new red algae spotted along the southern coast, one that marine ecologist Faith Coleman says is “nature’s clean-up crew”.

Noctiluca scintillans, known more commonly as Sea Sparkle due to its bioluminescence, is a form of non-toxic algae that according to Ms Coleman can eat the Karenia Mikimotoi currently affecting South Australia.

“What it’s doing is it’s eating the Karenia and all the other things that are blooming with it,” she told The Advertiser.

“When it dies, which is unfortunately what that cream is that you see on the surface mainly, it unfortunately releases quite a bit of ammonia from the digestion process, and also any toxins that were in the hazardous algae that it ate.”

Marine biologist Professor Shauna Murray from the University of Technology Sydney said that while Sea Sparkle was for the most part non-toxic, in high concentrations it could still cause fish kills.

Red looking algae has been spotted off Wirrina Cove. Picture: Facebook

Mr Eatts says he has been able to keep a steady income slowly selling his stock, which is now starting to run low. Picture: Facebook

“It pops up all around the country,” Professor Murray said.

“It’s not harmful, it doesn’t produce a toxin, but it can cause fish kills sometimes if it’s in very high abundance.”

Professor Murray was unsure whether or not Sea Sparkle would eat the Karenia Mikimotoi.

“It’s heterotrophic, so that means it can eat things,” she said.

“I’ve got no idea whether it eats Karenia specifically, I don’t know if anyone could say that for sure.”

Nathan Eatts said the Sea Sparkle off South Australia stretched for more than a kilometre, and was an estimated 30 metres in width.

“It was all the way pretty much from Rapid Bay to Carrickalinga,” he said.

“Where I found the thickest was right off of Wirrina Cove.”

More than 200 marine species have been recorded as dead due to the toxic algae bloom in SA. Picture: Supplied

Mr Tozer said he believed the general public had yet to fully understand the full scope of the destruction caused by the bloom in deeper waters. Picture: Lochie Cameron

Mr Eatts followed the Sea Sparkle into the evening, capturing footage of it glowing in the moonlight.

Ms Coleman said while the presence of Sea Sparkle was a “good thing”, it would not be a solid fix to the algal bloom, as it cannot handle large quantities of Karenia Mikimotoi, one of multiple “caveats” it had.

“It doesn’t eat fast, dense concentrations either, because it kills it eventually,” she said.

I call it nature’s clean-up crew.”

“It’s not the best clean-up crew in the world, because it’s like a clean-up crew that comes in, tidies everything after an event and then dumps it all in one corner.”

Further north in the Gulf St Vincent, six kilometres off Glenelg, diver Mark Tozer got a first-hand look at the devastation the algal bloom unleashed on the marine life around the Claris shipwreck, with him likening it to a post-apocalyptic scene.

Claris shipwreck around July 2024. Picture: Mark Tozer

Claris shipwreck post-algal bloom July 2025. Picture: Mark Tozer

“It was like Chernobyl had just blasted out there,” Mr Tozer said.

“It was horrible.”
Mr Tozer has been diving around the world for more than 35 years, and said he’d never seen anything like the algal bloom.

“Every time I go there it’s just fish and these beautiful fan coral, it’s a really pretty place.”

“But now it’s just devastated.”

Mr Tozer said he believed the general public had yet to fully understand the full scope of the destruction caused by the bloom in deeper waters.

“I just never realised, and I don’t think a lot of people do, that it’s a long way out, it’s deep water and it’s devastated it,” he said.

“Most people I talk to think it’s a beach problem, you know, fish are washing up on the beach, which is terrible.”

“But I don’t think people realise that this is actually a real marine problem, that it’s out deep.”

Originally published as SA diver shocked by the impacts of algal bloom on SA coastlines, but experts say glowing red algae is a promising sign