Sixty-one leafy seadragons, 604 Port Jackson sharks, 1,999 southern fiddler rays and 287 bluespotted goatfish make up a fraction of the dead washed up on South Australian beaches in the past months.
Since the algal bloom hit SA, hundreds of citizen scientists have come together to create what has become one of the main sources of data on the disaster.
Now more than 34,000 dead marine animals and fish have been logged by more than 900 observers – while, of course, far more have gone unobserved.
The bloom crept around the coast in March, unnoticed by most, until a surfer, Anthony Rowland, gave a colourful description of his and his mates’ hacking coughs after being in the water at Waitpinga, raising the alarm.
Next, pictures emerged of a mysterious, scummy foam on nearby beaches.
Then an algal bloom community, determined to do what they could, started to take shape.
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An ecologist, Faith Coleman, who has become a leading expert on the bloom, got in touch with Rowland.
“I sent him a Facebook message and a couple of questions,” she says. “One was, ‘Are you OK? I hear you’re really frustrated’, and the next was, ‘Can I do anything to help?’”
Someone else volunteered to courier a sample of the algae to Coleman and her mother, Peri Coleman. The pair run an ecological consulting firm and were able to test the sample and confirm it was Karenia mikimotoi (others were also toiling away on identification).
And so the mystery of the mucky foam was at least partly solved, although there are other Karenia species in the bloom and more questions to be answered.
Meanwhile, Brad Martin, SA project manager with the not-for-proift OzFish, and a marine ecologist, Janine Baker, seized the opportunity to set up a place where people could report what they were seeing in an organised way.
The iNaturalist app became the platform for an extraordinary citizen science project.
“There were a lot of photos on social media and in the media, which is great,” Martin says. “But not so useful if you’re trying to get scientific information about what’s been impacted.
Death on the sand: fish and animal carcasses rot on Adelaide shores amid toxic algal bloom – video
“The obvious advantage of the project is it’s public. Everyone can see it. The community can use it, researchers can use it, the government can use it.”
Observers have now logged almost 500 species with the SA Marine Mortality Events 2025 project. They range from the most commonly found (2,384 bluefin leatherjackets) to much rarer sightings – just one striped pyjama bottletail, one south-eastern biscuit star, one bighead gurnard perch – although these numbers are all changing daily, if not hourly.
With so many people logging their observations, double counting does happen, Martin says. And at the same time only some of the dead are observed – some will come and go with the tides, or remain unseen on remote beaches or under the water.
“But we get to see trends as it moves around,” he says.
Coleman says: “It’s hugely useful.”
Filling another knowledge gap, the Great Southern Reef Foundation has been gathering evidence of what is happening under the water, where reefs and seagrass meadows are devastated.
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They are also part of a movement lobbying governments to do more. In 2023 the foundation wrote to the federal government warning of the likely impact of marine heatwaves, a critical trigger for algal blooms.
It wrote again in May calling for a $40m, 10-year investment in a monitoring program.
State and federal governments have since opened up sources of funding and there is a $28m joint fund for science and research, to support local communities and industries, and to keep the public informed.
Coleman is critical of what she says was a slow government reaction that created a vacuum that allowed conspiracy theories to form.
But she says there’s an upside: “It enabled this community collective thing with everyone using their skills towards the greatest good.
“We’ve got a beautiful community; we seem to trust each other more than we trust government.”
Coleman says there is still a lot to learn.
Karenia species are always evolving and it’s impossible to pin down exactly what species are in the bloom, where and in what amounts. So far we only know a “drop in the ocean”, she says.
Some species emit brevotoxins, which can accumulate in shellfish and cause neurological symptoms in humans who eat them.
Different labs can report different results, and some species are incorrectly identified, while some species show up as brevotoxins on a screen even though technically they’re not.
“It’s the murkiest situation you can possibly imagine,” Coleman says.
But researchers are hard at work and benefiting from the citizen science under way.
Martin says the iNaturalist project is “community-owned” with support from OzFish, and that OzFish is using the information in the restoration work it was already doing – work that could help mitigate blooms in the future.
OzFish works with fishers and the community to protect and restore waterways. It has been restoring seagrass meadows, which have been ravaged by runoff, pollution and physical damage. Those meadows, when healthy, can help increase the resilience of the ecosystem and buffer against algal blooms.
OzFish is also constructing and restoring shellfish reefs with native oysters.
Experts are sceptical that existing mitigation methods will work on the scale of SA’s bloom. But those reefs provide a ray of hope – it turns out that native oysters eat Karenia mikimotoi.
“The community-led shellfish reef restoration has had some exciting results – native oysters not only surviving, they’re growing,” Martin says.
