‘Jellyfish joyride’ poses substantial threat to world’s oceans

June 10th, 2009 - 12:39 pm ICT by ANI  

Sydney, June 10 (ANI): A new research has presented convincing evidence that the increasing number of jelly fish, which is a substantial threat to the world’s oceans, is due to over-fishing and excess nutrients from fertilizers and sewage.

The research was led by CSIRO Climate Adaptation Flagship and University of Queensland scientist, Dr Anthony Richardson, and colleagues at the University of Miami, Swansea University and the University of the Western Cape.

“Dense jellyfish aggregations can be a natural feature of healthy ocean ecosystems, but a clear picture is now emerging of more severe and frequent jellyfish outbreaks worldwide,” said Dr Richardson.

“In recent years, jellyfish blooms have been recorded in the Mediterranean, the Gulf of Mexico, the Black and Caspian Seas, the Northeast US coast, and particularly in Far East coastal waters,” he explained.

“Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish. This would have lasting ecological, economic and social consequences,” he added.

“The most dramatic have been the outbreaks in the Sea of Japan involving the gargantuan Nomura jellyfish which can grow up to 2 m in diameter and weigh 200 kg,” he further added.

According to Dr Richardson, “Fish normally keep jellyfish in check through competition and predation, but over fishing can destroy that balance. For example, off Namibia intense fishing has decimated sardine stocks and jellyfish have replaced them as the dominant species.”

Climate change may favour some jellyfish species by increasing the availability of flagellates in surface waters - a key jellyfish food source.

Warmer oceans could also extend the distribution of many jellyfish species.

“We need to start managing the marine environment in a holistic and precautionary way to prevent more examples of what could be termed a ‘jellyfish joyride’,” he added. (ANI)

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