Great Barrier Reef shrinking to slimy seaweed forest

Incredible shrinking reef
Daniel Bateman, Townsville Bulletin 7 Jan 08;

THE Great Barrier Reef is shrinking and there could be nothing left but a slimy underwater forest of algae within 90 years, a scientist has warned.

The Australian Institute of Marine Science and James Cook University's Dr Eric Wolanski has created a frightening picture of what the reef is likely to look like by the year 2100. His study was based on past and future averaged coral cover on the Great Barrier Reef between Lizard Island and Bowen. Using physics and historic coral reef cover data, Dr Wolanski suggests the reef has been steadily shrinking since European settlement of Australia.

The main cause of this has been mud and chemicals washed onto the reef from farms, which has choked the coral, cutting it off from sunlight.

It has been shrinking at a rate of about 20 per cent every 100 years.

Dr Wolanski said the reef would continue to die off unless better land management controls were brought in.

"If we run our model forward, we see a steady decrease in the health of the reef," Dr Wolanski said.

"If you look at the reef cover, it's turning into slime, into algae.

"The picture we're seeing is we had about 65 per cent coral cover 100 years ago.

"We are now in the mid-40s. By 2050 we are in the mid-30s and in 2100 we are left with less than 10 per cent.

"We can recover about one-third of this loss if we cut the outflow of mud and nutrients by half from farms and cattle."

Last year the Inter-governmental Panel on Climate Change (IPCC) released a report which warned that the Barrier Reef would be `functionally extinct' within decades.

The report stated coral bleaching of the Barrier Reef was likely to become an annual event by 2030 because of warmer, more acidic seas.

Dr Wolanski said if the IPCC's prediction was accurate, it would not matter what action was taken.

"We won't have anything left," he said.

"Right now the problem is a land-use problem which we can correct and recover some of the losses if we take more care of the land.

"It is a much bigger issue than other global issues, otherwise we will be left with only an algal mat."

The coral reef around Dunk Island was one of the sites Dr Wolanski considered.

During February last year it was blanketed by mud for close to two weeks, he said.

Dr Wolanski described the existing reefs as representative of what the entire Barrier Reef would look like within the next 90 years.

"If you dive under the sea there you can see the shape of the old reef, but now it's all dead," he said.

"It's quite clear that the cause of this has been carried from the land."