Perth’s recent hot spell could be to blame for toxic algae outbreak in Swan River

Perth researchers believe our recent record-breaking hot spell could be the cause of the toxic outbreak poisoning the Swan River.

It comes after the Health department issued an urgent warning over a potentially toxic algae bloom.

Our city has had a record-breaking run of blistering conditions, with three consecutive days above 40C last week.

UWA researchers say evidence shows the recent heatwave could be to blame.

"What might be a trigger is unusual weather circumstances, namely heatwaves that we’re experiencing.” UWA professor Anas Ghadouani told 7NEWS.

“So certainly there’s science to support the hypothesis that in warmer conditions you have more algae bloom developing.”

The affected area extends from Pelican Point to Como Jetty and upstream to the Tonkin Highway bridge.

Swimming in those areas is still safe but should be avoided where there is a red discolouration in the water.

The warning didn't stop some swimmers today.

"You shouldn't really come in to contact for extended periods of time, but it's still OK to swim because those levels we're talking about are quite small in terms of toxins," professor Ghadouani said.

Recent testing has confirmed there are elevated levels of potentially toxic microscopic algae in the Swan River.

Doctors say eating contaminated fish and crabs could result in what is known as paralytic shellfish poisoning.

This can cause nausea, dizziness, numbness of the lips, slurred speech and in severe cases muscular paralysis.

The Health Department note cooking oysters, mussels, clams or fish will not destroy the toxins.