Perth’s Mullaloo Beach closed after algae outbreak

Swimmers have been told to stay out of the water at one of the country’s most loved beaches after a worrying find in the water.

A popular Perth beach could be closed for days, with swimmers being told to stay out of the water after an algae bloom outbreak.

Mullaloo Beach, 20km north of the city centre, was closed by lifesavers on Wednesday after trichodesmium algae was spotted in the water.

The blue-green algae, also known as sea sawdust, joins together in strings and clumps before it floats to the surface.

It's not yet known when the popular beach will reopen. Photo: Mullaloo SLSC

“If it is calm, these cells get the opportunity to aggregate into huge slicks that are sometimes so vast they are visible from space,” the Australian Institute of Marine Science says.

Despite its ability to cover vast areas, the algae is not considered harmful to humans but can cause minor skin irritation, prompting the warning from authorities, including the Department of Biodiversity Conservation and Attractions (DBCA).

“DBCA can confirm there is Trichodesmium bloom sighted in the water at Mullaloo beach on 17 January 2024,” a spokesperson said.

“This bloom has most likely formed due to the hot and calm conditions we have experienced over the recent days.

“It is recommended to not swim/walk through the bloom and keep pets away. If you do come in to contact, rinse with freshwater immediately.”

Authorities are currently testing water from the picturesque beach. Photo: Mullaloo SLSC

Perth has just sweltered through a searing heatwave in recent days, with the mercury twice going above 40C degrees

After the algae was discovered, Mullaloo Surf Life Saving Club warned beachgoers to stay out of the water on Wednesday.

“Beach is temporarily closed as there is potentially an algae bloom.

“At this stage it is unconfirmed and awaiting further testing and advice for the next couple of days.

“For everyone’s safety it is recommended to keep out of the water.”

Mullaloo SLSC will alert the community when it is safe to return to the water.

Originally published as Perth’s Mullaloo Beach closed after algae outbreak