Last updated: March 06, 2015


National Breaking News

Jellyfish blooms worry Aussie researchers

A bloom of sea tomato jellyfish on Cable Beach in Broome

An expert says not enough is being done to assess the effects of jellyfish blooms in Australia. Source: AAP

AN expert says not enough is being done to assess the ecological and economic effects of jellyfish blooms in Australia.

Dr Lisa Gershwin says there's growing evidence that some jellyfish species are exploding in number globally and there've also been some extraordinary blooms recorded recently in Australia.

She was shocked by photos of a recent bloom of so-called sea tomato jellyfish, near Broome, in Western Australia.

The event, recorded by seabird researchers, revealed the extreme effect jellyfish blooms can have on ecosystems, including non-marine species, Dr Gershwin told AAP on Friday.

"When the researchers got to the beach, the jellyfish were so thick the seabirds couldn't actually land to feed on crustaceans along the shore," she said.

"The researchers decided to travel on further but even after driving for 27 kilometres they still couldn't get out of the swarm.

"I've seen some photos of jellyfish blooms in my time but this one made me gasp."

She says there's evidence that some jellyfish species are on the rise globally and that's bad news for the marine environment.

"Jellyfish eat the eggs and larvae of fish and other species. They also eat the food those larvae would eat so there's sort of a double whammy effect," Dr Gershwin said.

"For this reason jellyfish can be really, really devastating to ecosystems and we're seeing this exact problem in many places around the world.

"Whether jellyfish are actually contributing to reduced fish numbers in Australia I don't know. We don't have enough data. But I think it's possible when we look overseas and see it's happening there."

She says more research is vital to ensure Australian fish populations don't reach a tipping point and crash due to the effects of jellyfish blooms.

"We know when jellyfish are on the increase you see larger blooms over time and you see fewer fish over time. The balance between jellyfish and fish goes haywire," Dr Gershwin says.

"We just don't have enough research on Australian jellyfish, and the dynamic between Australian fish and Australian jellyfish."

But Griffith University academic Dr Kylie Pitt, who has taken part in a multinational jellyfish study, says no strong evidence has been found of a global increase in jellyfish populations over the past 200 years.

"The key finding of this research was that global jellyfish populations undergo natural fluctuations, including a rising phase in the 1990s and early 2000s that has contributed to the current perception of a global increase in jellyfish abundance," she said in a statement on Friday.

"The previous period of high jellyfish numbers during the 70s went relatively unnoticed due to limited research on jellyfish at the time."

She said monitoring must continue over the next decade to determine if there really was an increasing trend in jellyfish populations after 1970, or if it was part of a larger oscillation.

But Dr Gershwin said the international study was too broad, looking at all species rather than those that were causing problems, and that "blurred" the result.