Huge jellyfish swarms hit Brisbane

In a boat harbour at Wynnum the water is thick with what scientists know as catostylus mosaicus - that's 'blue blubbers' to the rest of us.

Locals told Seven reporters that the water here is normally dark green, but with the large swarm in residence it appears an eery light blue.

There's very little current for the creatures to battle - so they're not expected to move on anytime soon.

Huge jellyfish swarms hit Brisbane

Huge jellyfish swarms hit Brisbane

"I'm from Scotland," one stunned tourist said, "so we don't see much like this."

Most Australians would no doubt find the sight a little disconcerting as well, but experts say it's nothing to worry about.

"We know that these populations oscillate through time, so you'll have several years where they'll be abundant and several years where they'll be scarce, and what's happening around Australia at the moment is we seem to be at one of these peaks of populations," Dr Kylie Pitt, a marine researcher said.

The jellies have been on quite a journey, with the Gold Coast's erratic king tides pushing them far up Tallebudgera creek before dragging them back to the ocean.

Similar blooms of jellyish appeared in the Gold Coast in Broadwater and areas of Moreton Bay in March last year.

Marine researchers believe it's likely many of the creatures are left over from that event.

The species is normally eaten by fish - but it would likely take several years for the present horde to be consumed.

"Often people find these big blooms of jellyfish and they worry that it is a sign of something out of kilter in the ocean or it's a sign of an unhealthy ocean," said Dr Pitt.

"But we now know that jellyfish are a really important part of the ocean and it's not necessarily a sign of the ocean being degraded or in trouble."