THEY are the mighty rainforests of the ocean, towering up to 25 metres from the seabed. Like many forests on land, the giant kelp jungles in the waters off south-east Australia are gravely threatened by climate change, scientists say.

In some areas off the east coast of Tasmania they have shrunk by more than 95 per cent, according to CSIRO experts.
The threat is so serious Environment Minister Tony Burke has listed the forests as endangered - the first time a marine ecological community has been given such protection under federal environmental law.

''Giant kelp forests are being progressively lost due to a warming of the sea surface temperature caused by climate change, invasive species and changing land use and coastal activities that contribute to increased sedimentation and runoff and biodiversity loss,'' Mr Burke told The Saturday Age yesterday.

The forests are a rich ecosystem and habitat for important species, including black lip abalone and southern rock lobster.

His remarks came as the CSIRO released a marine health snapshot that provided evidence for what scientists have long suspected: climate change has strengthened the East Australian Current, which moves down the east coast, driving marine species south to seek colder waters.

The only remaining kelp forests are around south-east Tasmania, south-east South Australia and western Victoria.
Listing the forests as endangered means that restrictions could be placed on activities that exacerbate the threat, such as overfishing, dumping waste and land uses that wash too much sediment into the sea.

Karen Gowlett-Holmes, a marine biologist with the CSIRO and co-owner of Eaglehawk Dive Centre on the east coast of Tasmania, said the destruction of the kelp forests was having ''a huge impact'' on marine ecology.

''If you can imagine what happens in an area where someone comes in and clear-fells a rainforest, this is essentially what's happened,'' she said.

Dr Gowlett-Holmes said that the minimum winter water temperatures off south-eastern Tasmania had risen 20 per cent over the past two decades. Giant kelp need the cold winter waters to grow back after the natural cycle of destruction in sea storms.

Sea urchins, which devour the kelp, are at pest proportions, as they prefer warmer water and their natural predators, rock lobsters, have been overfished.


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