Monday, May 31, 2010

Researchers claim that giant jellyfish are over running the world's oceans as a result of overfishing and other activities of humans.

Dr. Anthony Richardson, CSIRO Marine and Atmospheric Research, and his colleagues have reported their findings in the Trends in Ecology and Evolution journal.

"We need to take management action to avert the marine systems of the world flipping over to being jellyfish dominated," said Richardson, who also happens to be a marine biologist at the University of Queensland.

He also said that the numbers of jellyfish are rapidly increasing, particularly so in the Black Sea, the Gulf of Mexico, Southeast Asia and in the North Sea. He also said that the Japanese are facing a major problem caused by giant jellyfish bursting through fishing nets.

"(They're) a jellyfish called Nomura, which is the biggest jellyfish in the world. It can weigh 200 kilograms, as big as a sumo wrestler and is 2 meters in diameter," said Richardson.

Richardson and his colleagues have reviewed literature that links jellyfish blooms with the problems of overfishing and eutrophication – that is, high levels of nutrients.

Richardson said, "Jellyfish are normally kept in check by fish, which eat small jellyfish and compete for jellyfish food such as zooplankton."

But is has been observed that jellyfish numbers are on the rise due to overfishing. Fish numbers have been further impacted by the fact that jellyfish feed on fish eggs and larvae. Furthermore, due to nitrogen and phosphorous in run-off, red phytoplankton blooms, creating low-oxygen dead zones in which jellyfish can survive, and fish don't.

Richardson said, "You can think of them like a protected area for jellyfish."

He and his colleagues claimed that climate change can increase the production of more jellyfish. They also said (for the first time) that these conditions could lead to what they consider a ‘jellyfish stable state', whereby jellyfish could rule the oceans.

Richardson and his colleagues have recommended a course of action in their paper, to coincide with World Oceans Day. These recommendations include:

• Reduce overfishing, especially of small fish like sardines, and to reduce run-off.


• Control the transport of jellyfish in ballast water and aquariums.

Researchers are experimenting with different methods to control jellyfish, said Richardson. Some of these methods involve the use of sound waves to explode jellyfish, while some use special nets to try and cut them up.

http://www.abc.net.au/science/articles/2009/06/08/2592139.htm

Read more Jellyfish News

Learn more about Jellyfish, different Jellyfish Species, general Jellyfish Information, Jellyfish Pets and Jellyfish Safety