Four suspected Irukandji jellyfish stings at K'gari spark theories over rising numbers

Infants have been among the victims of suspected jellyfish stings. But is it the presence of humans, the weather, or even climate change causing the problem?

Deadly jellyfish are suspected to be behind a spate of hospitalisations of tourists swimming at a popular holiday island, described by medical staff as somewhat of an anomaly.

LifeFlight first responded to a girl with a suspected sting on K’gari, formerly Fraser Island, on Sunday, and she was airlifted to Hervey Bay Hospital. On Monday, a man and an infant were separately choppered back to the mainland between 1 and 3.30pm, both had suspected Irukandji jellyfish stings.

While three hospitalisations in such quick succession are rare, medical staff responded to a fourth victim on Tuesday at around 1.30pm (Queensland time). Details of the emergency are still unclear, but all of the attacks have occurred on the western side of K’gari, parts of which are thought to be safer for families.

Background - a stinger sign on a QLD beach. Inset - a box jellyfish
A fourth person is suspected of falling victim to a jellyfish bite at K'gari. Source: Getty (File)

Was weather a factor behind the jellyfish stings?

Irukandji are a small and extremely venomous jellyfish about one cubic centimetre in size, and although deaths from the species are rare, two people died of stings in Queensland in 2002. They have been reported off K’gari for almost two decades, and there are several reasons why the sudden cluster of stings occurred.

Recent weather systems are certainly one possibility. Professor David Schoeman from the University of the Sunshine Coast told Yahoo News Australia the increased presence of Irukandji also coincides with a long period of strong onshore winds, and these can bring oceanic waters to the coast, and this usually results in bluebottle stings.

Schoeman believes the intensification of the East Australian Current could also be helping the species migrate from northern breeding grounds. These could have helped a sudden cluster of Irukandji travel south to waters around K’gari, sparking a "rare" spate of stings. “The same sort of thing happens with shark attacks. You may have years with very low numbers or none at all. Then sometimes you get a year with a whole bunch in the same place.”

Are the school holidays responsible for the stings?

James Cook University PhD candidate Scott Morrissey has expertise in deadly jellyfish and believes the reason for the stings could actually be more of a human problem.

Scott Morrissey holds a large jellyfish
Scott Morrissey (pictured) is warning there isn't enough funding to properly track how climate change is impacting the distribution of jellyfish. Source: Supplied

“It’s hard to draw conclusions, but we’re at the end of the school holidays and it’s very hot, so there are going to be more people in the water, so you could expect to see more stings,” he said.

“Because they’ve been there for the last 15 to 20 years the message has to be, if you’re going to swim there, wear a stinger suit. You’ll never catch me in the water without one during the season.”

What role is climate change playing?

Because the Irukandji have been detected for years at Fraser Island, Morrissey believes they could be breeding there and the jellyfish research community is concerned they will continue to move south as waters warm because of climate change.

Morrissey said he’s “pretty confident” that Irukandji are breeding close to Fraser Island, but he stressed that with so little research funding available, this hypothesis remains theoretical.

But Schoeman is sceptical that there is a permanent population, and thinks it more likely they are breeding to the north because K’gari’s sandy seabed is unfavourable to their larvae which need to attach themselves to the seafloor.

“Although we may see more periodic influxes of adult irukandji, I think that it will be a rare occurrence that we will frequently see large numbers as far south as K’gari,” he said.

“I’d be quite surprised to see a major change before 2050,” he added. “But that's an educated guess. We really don't have the monitoring data infrastructure or funding in place in Australia. That’s one of the major limitations we have in making predictions.”

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