Swarm of jellyfish swimming in bioluminescence looks ‘magical’ – but it’s a warning sign

Biologist says the massive numbers of jellyfish and algae in Tasmania's Storm Bay are drivers of harm in the ocean'

• Follow our Australia news live blog for latest updates
• Get our breaking news email, free app or daily news podcast

A magical" swarm of moon jellyfish colliding with algae dazzled onlookers this week, but it comes with a warning.

The bloom of jellyfish - temporary increases in populations - has occurred over the past few weeks in Storm Bay, east of Hobart, and as far as halfway up Tasmania's east coast. The biologist and jellyfish expert Lisa-ann Gershwin said the population growth was unprecedented" and had stepped up dramatically" last month.

Sign up for Guardian Australia's breaking news email