‘Jellyfish Joyride’ a threat to the oceans

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 fertilizers and sewage.

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,' Dr Richardson says.

The new research, by Dr Richardson and colleagues at the University of Miami, Swansea University and the University of the Western Cape, has been published in the international journal.

Fish normally keep jellyfish in check through competition and predation but overfishing can destroy that balance,' Dr Richardson says. Climate change may favor 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.