'Trojan horse' effect may explain jellyfish blooms

September 7, 2012
'Trojan horse' effect may explain jellyfish blooms

(Phys.org)—Man-made structures such as harbours, tourist facilities, oil rigs and aquaculture farms provide ideal sanctuaries for jellyfish polyps to flourish and may explain an apparent increase in jellyfish blooms in many coastal waters around the world.

That's the conclusion of a new study published by a group of international researchers, including lead author Winthrop Professor Carlos Duarte, Director of the Oceans Institute at The University of Western Australia.

Their paper Is sprawl a cause of blooms? appeared this week in the journal Frontiers in Ecology and the Environment.

Professor Duarte said most theories that seek to explain increased jellyfish blooms focus on jellyfish at their more mature swimming stage and factors such as a lack of predators or competitors due to overfishing.

But the new study examined the tiny polyp phase of jellyfish and found they congregate in millions on the underside of man-made structures.

"We call this new proposition the '' hypothesis," Professor Duarte said.

"The proliferation of such as harbours, shipping facilities and aquaculture structures provides a habitat for jellyfish polyps and may be an important driver in explaining the global increase in jellyfish blooms."

Professor Duarte said jellyfish larvae typically settle on a hard surface and grow into polyps as part of a colony.  The polyps are generally inconspicuous because they are very small - usually only a millimetre or so in length.

The study examined polyps growing on a variety of man-made structures around the world - including in Japan, Britain, Spain and Slovenia - and looked under docks, piers, pontoons and , and on the underside of oysters attached to piers.

"Jellyfish existed on the underside of such artificial structures at densities of more than 10,000 individuals per square metre, and sometimes up to 100,000 per square metre," Professor Duarte said.

Research was also conducted in Chesapeake Bay in the US and in a laboratory with a Mediterranean jellyfish species to examine how larvae settled on oyster shells, flagstones and 16 other surfaces, including bricks, ropes, cans, wood, concrete and plastic.

Explore further: Dutch zoo breeds own jellyfish

Related Stories

Dutch zoo breeds own jellyfish

September 29, 2007

Marine biologists at a Dutch zoo say they have succeeded in the difficult task of breeding jellyfish in captivity.

Spanish resort in jellyfish alert

May 27, 2011

Authorities in the Spanish tourist hotspot of Benidorm said Friday they have reopened its beaches to tourists after removing more than a tonne of dangerous jellyfish.

Global experts question claims about jellyfish populations

February 1, 2012

Blooms, or proliferation, of jellyfish have shown a substantial, visible impact on coastal populations – clogged nets for fishermen, stinging waters for tourists, even choked intake lines for power plants – and ...

Jellyfish on the rise: study

April 18, 2012

Jellyfish are increasing in the majority of the world's coastal ecosystems, according to the first global study of jellyfish abundance by University of British Columbia researchers.

Recommended for you

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

Insect DNA extracted, sequenced from black widow spider web

November 25, 2015

Scientists extracted DNA from spider webs to identify the web's spider architect and the prey that crossed it, according to this proof-of-concept study published November 25, 2015 in the open-access journal PLOS ONE by Charles ...

How cells in the developing ear 'practice' hearing

November 25, 2015

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.