What happened to Tasmania's giant kelp forests?
Tasmania's giant kelp forests have declined by more than 90 percent since the mid-twentieth century, mainly because warming seas, driven by a stronger East Australian Current, brought warmer, nutrient-poor water.
Giant kelp is a large brown seaweed that can grow up to around 30 metres long, rising from the sea floor to form floating canopies. These underwater forests once lined much of Tasmania's east and south coasts.
Kelp forests are home to fish, abalone, rock lobsters, seadragons and many other species. They are among the most productive ecosystems in the ocean.
Why the forests disappeared
Waters off eastern Tasmania have warmed faster than most of the world's oceans. Warm water carries fewer nutrients, and kelp struggles. The long-spined sea urchin, which spread south from New South Wales, also grazes kelp, creating barren reefs.
Giant kelp forests in southeast Australia were listed as an endangered ecological community in 2012, the first marine community listed under national law.
Scientists are now breeding heat-tolerant kelp and replanting it on reefs, and divers remove urchins. Some small patches of kelp still survive, giving hope for restoration.
Did You Know?
Giant kelp can grow up to about half a metre in a single day under good conditions.