The thick underwater forests off Tasmania’s east coast used to be so dense they were marked as shipping hazards on nautical charts. Thriving stands of giant kelp, which grows up to 40 metres high, once provided habitat for fur seals, seahorses, weedy sea dragons, rock lobsters, abalone and fish.
Since the 1960s, Tasmania’s giant kelp has all but vanished. Despite the rapid speed at which the brown algae grows – up to half a metre a day – around 95% has been killed off by warm waters pushed southwards by the east Australian current.