Scientists reveal reason why ‘toxic’ foam washed up on South Australian beaches

Scientists have discovered why a revolting foam washed up on the shores of beaches, killing marine life and causing beachgoers to get sick.

Scientists have confirmed what caused the mysterious foam on South Australian beaches that killed marine life and caused swimmers and surfers to fall ill.

Reports first emerged of a yellow and sludgy-coloured foam washing up on the Fleurieu Peninsula - including Waitipinga Beach, Parsons Beach, Cape Jervis, and Encounter Bay - in mid-March.

Dozens of surfers and beachgoers soon reported flu-like symptoms including a dry cough, sore throat, and irritated eyes.

Residents were horrified to find scores of dead fish along the coast. Picture: Facebook

Locals also reported feeling sick after being exposed to the water. Picture: Facebook

As beachgoers began reporting “blurred vision” after spending time in the water, scores of dead marine life, such as seahorses, octopuses and fish, also started washing up on shores.

“Something weird is in the water,” resident Anthony Rowland shared on social media at the time.

The Environmental Protection Agency (EPA) confirmed on Tuesday that an investigation had determined the unusual foam was caused by a microalgae bloom called Karenia mikimotoi.

The bloom is toxic to fish and marine life but is not poisonous to humans, their statement said.

The EPA said it could however cause a general allergic-type reaction in people, with symptoms such as stomach upsets, respiratory and eye irritations, skin rashes, and other flu-like symptoms.

“These symptoms disappear when the exposure stops or following washing in clean water,”
SA Health principal water quality adviser David Cunliffe told NewsWire.

“There are no long-term effects.”

Residents were horrified to find scores of dead fish along the coast. Picture: Facebook

The EPA confirmed Waitpinga Beach and Parsons Beach would remain closed until further notice.

Visitors have been cautioned to adhere to the warning signs located at other council-run beaches.

“Now we know exactly what we are dealing with, I would encourage people to avoid

the water and shoreline along the affected beaches,” Deputy Premier Susan Close said in a statement.

“The EPA will continue to monitor the microalgae bloom and beaches will reopen as

soon as it dissipates.”

EPA principal scientific officer Sam Galyard told ABC Adelaide it was a “fairly natural” occurrence to see the algae bloom and cause a mass fish casualty.

A sludge-coloured foam and several dead fish have been sighted on the beaches of Waitpinga Point to Victor Harbor, causing a stir in the community. Picture: Facebook

Scores of dead seahorses were spotted along the beach. Picture: Facebook

A Karenia mikimotoi bloom typically occurs during a marine heatwave, which the state is currently experiencing, with recorded marine temperatures 2.5C above average.

This, combined with relatively calm marine conditions, little wind and a small swell, caused the algae to bloom to the colossal size.

It was first recognised in Japan in 1935 and has caused mass mortalities for fish and other sealife in the US, Norway and New Zealand – the last time an algae bloom this size was present at a SA beach was in 2014 in Coffin Bay.

The change in sea conditions could be attributed to climate change, Ms Close said.

“With temperatures, including water temperatures, continuing to rise as part of climate change, we need to remain vigilant for these type of events and I thank everyone who took to the time to report the bloom to authorities,” she said.

It is not yet known how long the microalgae will last in the water, but Mr Galyard hopes a cool change could soon eradicate the toxic substance.

“What we’re really hoping for is a big cold front to come through, some strong westerly winds, and that’ll break it up and disperse it,” he told the ABC.

“Until then, we’re just expecting it to slowly dissipate with increased tides and hopefully a bit more wind.”

It is not yet known how long the microalgae will be in the water. Picture: Facebook

In mid-March, residents described feeling sick after being near or in the water, some of which felt the symptoms for more than 24 hours after exposure.

One local recalled feeling short of breath and experiencing pain in their throat after walking on the beach.

“Immediately, I began coughing and felt (a) burning nostril sensation the whole time,” they wrote on social media.

A resident, who was collecting shells at Middleton on the eastern of the Fleurieu Peninsula, reported the air feeling “super thick”, which made it hard to breathe.

Another woman said she and her friends began coughing after visiting one of the beaches.

“(It) felt like something (was) stuck at the back of our throats,” she said.

Mr Galyard said this was likely due to the algae being propelled into the air due to crashing waves.

“So when these particles get into the air through the disturbance in the waves crashing … it gets into the lungs and eyes and can irritate them,” he told the ABC.

Anyone exposed to the microalgae have been told to wash the area in clean and freshwater.

“In general, people should avoid contact with discoloured fresh or marine water,” Mr Cunliffe said.

“If they do enter this water they should take care to wash in clean water afterwards.”