A mysterious foam has washed up on south Australia’s beaches, coinciding with fish deaths and surfers falling ill with symptoms like coughing, sore throat and blurred vision.
The foam has covered hundreds of metres along Waitpinga Beach, about 15km southwest of Victor Harbor.
Several people who visited the beach over the weekend experienced cold and flu-like symptoms afterwards.
Parsons Beach, another popular surfing spot just west of Waitpinga, is also affected.
Scores of marine animals, including seahorses, fish and octopuses, have washed up on the sand, and visitors have noticed a visible “slick” on the water.
The Department for Environment and Water has temporarily closed both Waitpinga and Parsons, nearly 80km south of Adelaide, citing a possible link between the foam and a microalgal bloom, likely triggered by hot temperatures, stagnant water and an ongoing marine heatwave.
The Department of Primary Industries and Regions is investigating the “fish mortality event”.
A department spokesperson said that its “role in this type of incident is to investigate the cause of the fish kill to rule out infectious and notifiable animal diseases, establish the cause, and coordinate a response where necessary.
“Fish kill events can be brought on by a variety of causes including environmental factors such as temperature, rainfall (or lack of) and water quality including salinity or oxygen levels, or by disease or pollutants.”
A local surfer, Anthony Rowland, told the Australian Broadcasting Corporation that he visited Waitpinga on Saturday morning with a few friends.
“While we were out there, we started coughing,” he said. “We came in and we kept coughing after walking up the hill, and a few people in the car park came over and they said that they’d experienced the same coughing and they hadn’t even hit the water yet.”
What is making beachgoers sick and killing marine life on the Fleurieu Peninsula? SA surfers have raised the alarm after falling ill while out on the state’s south coast. A mysterious sea foam has been washing ashore as well as dozens of dead sea creatures. Now, authorities have… pic.twitter.com/4qbjNNH12j
— 7NEWS Adelaide (@7NewsAdelaide) March 17, 2025
Mr Rowland said he experienced sore eyes, sore throat and coughing which “continued all day”.
After he posted about his experience on social media, many people responded that they had experienced similar symptoms after visiting the beach.
“Lots of people reached out,” he said, “so many people have said they have had exactly the same symptoms.
It’s quite overwhelming. I’d say that pretty much every single person that went in the water at Waitpinga, bar one young fella that had a quick half-an-hour surf, has reported the same symptoms.”
After speaking with other people, Mr Rowland said, he estimated there were more than 100 people affected.
Another surfer, identified by local media as Andy from Middleton, said he visited Parsons on Saturday morning and afterwards received messages from several friends reporting sore eyes and feeling unwell.
“They had coughs, they had breathing difficulties when they were driving home back to Adelaide,” he told ABC Radio Adelaide.
“A lot of people come down here on the weekends to surf from Adelaide and I had 30 or 40 messages with the same symptoms and they actually said their friends had it as well.
“Some people reported a bit of a slick on the water too. A couple people said they saw a lot of green on the beach, but yesterday there was a lot of foam, a lot of brown on the beach as well. There’s lots of different theories going around at the moment.”
There is a health warning for SA beachgoers on the south coast where a mystery illness has struck down dozens of surfers and is killing hordes of fish. Surfers have told 7NEWS they developed ear, eye and throat infections after entering the water at Waitpinga Beach which is now… pic.twitter.com/Su8kPUrHsC
— 7NEWS Adelaide (@7NewsAdelaide) March 18, 2025
South Australia Health principal water quality adviser David Cunliffe told Nine News that exposure to algae can trigger allergic reactions, including respiratory and eye irritation or skin rashes, while ingestion may lead to stomach upsets or flu-like symptoms.
“These symptoms disappear when the exposure stops or following washing in clean water,” he said. “People should avoid contact with discoloured fresh or marine water. If they do enter this water they should take care to wash in clean water afterwards.”
Ocean Watch Australia states on its website that “most sea foam is not harmful to humans and is often an indication of a productive ocean ecosystem. But when large harmful algal blooms decay near shore, there are potential for impacts to human health and the environment”.
“During blooms popping sea foam bubbles are one way that algal toxins become airborne. The resulting aerosol can irritate the eyes of beach goers and poses a health risk for those with asthma or other respiratory conditions.”
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