SEVERAL popular Sydney beaches, including the iconic Bondi, have been closed after patches of red algae were spotted in the water.
Patches of the red algae, a natural phenomenon that can be exacerbated by certain weather conditions, have been sighted between Bondi Beach and Maroubra Beach this morning.
Both Bondi Beach and Clovelly Beach are closed while authorities conduct tests in the water.
Gordon’s Bay was also closed due to the algal bloom, with Beachwatch posting a photograph on Twitter showing water the colour of tomato juice.
Waverley head lifeguard Bruce Hopkins said the bloom was spotted drifting off the north side of Bondi Beach at around 6.30am.
“It has got quite a fishy smell to it,” Mr Hopkins told AAP.
“It can irritate some people’s skin but generally not much more than that.”
Mr Hopkins said the bloom has a “reddy-purple” tinge and sits on the surface like oil sheen.
The bloom was dissipating off Bondi, with hopes the beach might be reopened by this afternoon, he said.
Red algae was uncommon but not unheard of at Bondi, Mr Hopkins added.
At just before 12.30pm Beachwatch NSW announced that Clovelly Beach had also been closed because of the bloom.
The closures will come as a blow to tourists and other beachgoers if they continue throughout a week which is forecast to have soaring temperatures peaking at more than 40C on Saturday.
A Randwick Council spokesman said red algae can potentially be dangerous to humans exposed to it.
“There are some possible risks to human health from red algae including skin rashes and eye irritation, and for this reason the beach will remain closed until the algae dissipates,” the spokesman said.
“Signage has been installed at Clovelly Beach, and council lifeguards are advising people not to swim.”
A spokesman for the NSW Office of Water said testing was being done to discover what caused the bloom.
One cause, he said was an upwelling of colder nutrient-rich water.
He said algal blooms, sometime referred to as “red tides”, are more common around spring and autumn when there are higher water temperatures and greater movements in ocean currents.
The NSW Office of Water expects the test results some time on this afternoon but could not confirm the beaches would be opened by the end of the day.
It comes after toxic algal bloom was detected in Botany Bay, south of Bondi on Friday.
That particular species of algae produced paralytic shellfish poisoning toxins, the NSW Department of Primary Industries said.
The NSW Office of Water spokesman said the two blooms were “probably not related”, but were unable to confirm further details until test results on the algae at Bondi became available.
While many locals have been deterred by the phenomenon, many people – believed to be tourists – are still swimming in the water.
Bondi local Michael Strum said the algae had stopped him swimming in the water.
“It looks like pink sludge, it’s disgusting,” he said.
“You can even see it on the sand.”
Irene Eristian, 33, said the colour of the water was “quite intense”.
“I wasn’t sure if I should let my daughter into the water as I wasn’t sure what it was,” she said.
Some, like 18-year-old Bondi woman Josie Capel, said she was curious to find out what the effects are and “what the risks are, if there are any”.