Underwater Gardening as Last Resort, UQ News Online, 09/05/06
Australians may have to resort to "underwater gardening" if they are to protect their priceless coral reefs through the stresses of climate change.
Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) say that the if the coral bleaching events of 2002 and this year are anything to go by, climate change holds some major adverse impacts for systems such as the Great Barrier Reef and Ningaloo in Western Australia.
Professor Ove Hoegh-Guldberg, of CoECRS and The University of Queensland, said a recent study found that the Great Barrier Reef, a UNESCO World Heritage area, had experienced unprecedented rates of bleaching over the past two decades.
The study conducted for the Australian Business Round Table by CSIRO also found that an additional warming of only 1°C was anticipated to cause considerable losses or contractions of species associated with coral communities.
Up to half the reef could be bleached every year with only a 1 degree warming, the report said. Two degrees' warming would result in bleaching of up to 80 per cent of the reef area.
“In such circumstances, we'd see a role for limited activity to physically protect or even re-seed damaged reefs, especially in areas of particular economic or environmental significance,” Professor Hoegh-Guldberg said.
“Of course the Great Barrier Reef itself is too vast to reseed with corals, but in particular areas there may be a case for transplanting mature corals or releasing coral spawn to accelerate the processes of reef recovery.”
While the idea of replanting a reef is still controversial, it is conceptually similar to revegetation and river recovery programs taking place on land across Australia, he says.
One of the main challenges will be to restore a number of inshore reefs, which have been destroyed or extensively damaged by sediment, nutrients and coral bleaching caused by human activity on the land over the past 40 years, he said.
“If we can fix the water quality problems which are causing the loss of these reefs – as we are starting to do in inland rivers – it may be these coastal reefs will provide a good place to try large-scale coral restoration.”
However coral bleaching events caused by bodies of warmer water circulating over the reef can be so extensive - as in 2002 - that little can be done about the huge areas killed.
“We may eventually have to look at the possibility of harvesting corals from the north of the reef (where they have adapted to warmer waters) and move them to the south, or take corals from outer to inner shore reefs to help maintain coral populations in particularly significant or important areas," he said.
“The technological challenges are enormous.”
Professor Hoegh-Guldberg said the CoECR was working with the Coral Reef Targeted Research Project funded by The University of Queensland, World Bank and the Global Environment Facility to explore techniques for restoring and managing coral reefs through climate change and other impacts.
This is expected to yield a range of methods for active intervention to keep reefs healthy in the face of rapidly changing conditions, temperatures and extreme weather events.