The Federal Government has listed the giant kelp forests near Tasmania, Victoria and South Australia as endangered.
Under the listing, the giant kelp are considered an endangered ecological community.
Any projects which could impact on the forests will now require assessments under national environment law.
Giant kelp are mainly found from Eddystone Point in north-east Tasmania, and along the state’s east coast as far down as Port Davey in the south-west.
Federal Environment Minister Tony Burke says the move will ensure better protection for the forests, which are being threatened by warming oceans, invasive species and human activity on coastlines.
Greens Senator Peter Whish-Wilson has warned the marine forests will remain under threat unless further action is taken to address climate change.
“Everything helps in a situation like this but my understanding is that global warming and rising sea temperatures are the key problems for kelp,” he said.
“So unless we address the gases that cause global warming and take effective action on climate change, no listing in the world is going to help kelp forests.”