ScienceDaily (June 10, 2009)
— Early action could be crucial to addressing the problem of major increases in jellyfish numbers, which appears to be the result of human activities.
New research led by CSIRO Climate Adaptation Flagship and University of Queensland scientist, Dr Anthony Richardson, presents convincing evidence that this ’jellyfish joyride’ is associated with over-fishing and excess nutrients from fertilisers and sewage.
“Fish normally keep jellyfish in check through competition and predation but overfishing can destroy that balance,” Dr Richardson says. “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.
“Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish,” Dr Richardson says “This would have lasting ecological, economic and social consequences.