Twenty-two people have been hospitalised this summer with Irukandji stings, which can cause brain haemorrhages

This article is more than 1 year old

This article is more than 1 year old

The deadly Irukandji jellyfish is likely to spread further down Australia’s east coast as temperatures warm, an expert says, after twice as many Queenslanders were stung by the species this season than usual.

Twenty-two people have been hospitalised this summer with Irukandji stings – which are so severe they can cause brain haemorrhages and a debilitating sensation of impending doom, known as Irukandji syndrome.

At the same time, nearly 5,000 people suffered the milder sting of the bluebottle, which massed in a record-breaking armada along the Sunshine Coast and Gold Coast last weekend.

Jellyfish sting more than 5,000 holidaymakers on Queensland's coast Read more

Bluebottles have stung 22,282 people in the five weeks from 1 December to 7 January, and 1,000 were stung within a few hours on Sunday. Last year, only 6,831 people were stung in the same five-week period.

But the potentially fatal Irukandji stings – especially near Queensland’s Fraser Island – are sparking the most concern.

Prof Jamie Seymour from James Cook University said the density of Irukandji, a species of box jellyfish, and the rate of stings had been steadily growing in southern Queensland as sea waters warmed.

“We published a paper some years back looking at Irukandji syndrome in Queensland and we had a look at the number of stings,” he said. “Fifty years ago the southernmost sting for Irukandji was in the Whitsundays, and now the southernmost sting is Mooloolaba beach. And if you look at the number of stings at Fraser Island, they are steadily increasing. More and more animals are getting down there.

“Lifesavers down there are dragging them up very easily.”

The tropical box jellyfish likes to live in water temperatures higher than 29C and are normally found in the northern tropics.

There have been two confirmed Irukandji deaths in Australia but the mysterious deaths of at least three tourists have been linked to the jellyfish.

Seymour said Irukandji would inevitably move further south if waters continued to warm.

“We know the temperature they prefer, and what we need is the data of where those water temperatures will occur,” he said. “If it will be 29C for two months on the Gold Coast in three years’ time, I can tell you there will be Irukandji down there.

“In Queensland alone, we put more people in hospital due to Irukandji stings than shark attacks, crocodile attacks and snake bites combined. This is something that we need to address now. I can see a time when we have to shut major beaches on the Sunshine Coast. It is going to happen.”

He added that the current spate of stings at Fraser Island was due to “a perfect storm” of conditions: warmer water, more Irukandji and more people in the ocean during the Christmas holidays.

“You have hot water down there which is 29 or 30C, which is unheard of,” he said. “The animals love that sort of thing. The people being stung are on the western side of Fraser Island, where it is nice and calm, and this has coincided with the Christmas break where you have more people in the water.”

Bluebottle 'epidemic': thousands stung as record numbers swarm Queensland beaches Read more

Another marine biologist, Dr Lisa-ann Gershwin, said that some swimmers could even be encountering a rare, giant species of bluebottle that was only spotted every “10 to 30 years”.

However, she said it was very rare, and a spokesman for Surf Life Saving Queensland said lifesavers had not reported seeing the larger bluebottle.

Gershwin has written on her website that climate change and warmer water was likely to lead to increased jellyfish populations.

But she told the ABC this week that it was “nothing new” that Irukandji were found at Fraser Island. “We’ve found them south of Fraser Island for more than 100 years,” she said.

Seymour said that it was possible for larger bluebottles to inflict Irukandji syndrome because jellyfish venom changed with age and size.

“We know that bluebottles under some circumstances give rise to Irukandji syndrome,” he said. “It appears they have a different venom when they are small than when they are large. This is not unknown in jellyfish – their venom changes as they age.”