New research led by CSIRO Climate Adaptation Flagship and University of Queensland scientist, Dr Anthony Richardson, presents convincing evidence that this ’jellyfish joyride’ is the result of human activities. It is due to over fishing and excess nutrients from fertilizers and sewage. He believes that early action could be crucial to addressing the menace of increasing jellyfish.
Dr Richardson explained that 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. It is true that Mediterranean, the Gulf of Mexico, the Black and Caspian Seas, the Northeast US coast, and particularly in Far East coastal waters have been witness to the problem of increasing jellyfish
It is told that 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. According to Dr Richardson fish normally keep jellyfish in check through competition and predation but overfishing can destroy that balance.
Citing a good example of Namibia Dr Richardson said that the 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.
