Every year an ocean current supercharged by climate change brings a destructive, spiky species south from New South Wales to the rocky reefs of eastern Tasmania.
The long-spined sea urchin is bad news for Tasmanian sea life as the species can quickly nibble swaying kelp forests to bald rocks, forming underwater moonscapes known as urchin barrens.
Seaweed is important food and habitat for the animals of a rocky reef, so when urchins create a barren it's akin to clear-felling a vibrant rainforest.
