Fiji reefs hit by climate change

Climate change and a starfish outbreak have shrunk coral reefs near Fiji, forcing locals to change their lifestyle.

A new study, published in Global Change Biology, has found that from 2000-2006 the size of coral reefs around Fiji's remote Lau Islands contracted by about 50 percent.

Dr Nick Graham from James Cook University, who took part in the study, says fishing and habitat disturbance are having a big impact.

"The area was disturbed by a crown of thorns starfish outbreak in about 2000 and then, the subsequent year, there was also a coral bleaching event associated with climate change," Graham said.

"We were pretty shocked at just how severe the impact was." He said so-called "bottom up" pressure from habitat changes was reducing the number of small fish, while "top down" pressure, from fishing, reduced the availability of larger fish.

The local population has fallen and people have changed their diet.

"Their actual dependence on protein, on fish resources, has reduced," Graham said.

"The population size on the islands has gone down. They seem to be getting more and more involved with land-based agriculture.

"And the price of tanoa bowls, which they traditionally carve in those islands, has gone up greatly." Locals fishing around the five islands surveyed has been cut back by an average of about 40 percent, he said.

Climate change hurt the reefs because warmer water stressed the coral, causing it to bleach and ultimately die, he said.

Graham said it was uncertain whether the crown of thorns outbreak was a result of climate change, too, although studies had linked outbreaks to increases in nutrients in the water or overfishing of starfish predators.

He said there were lessons to be learned from the study for the management of other reefs, including Australia's Great Barrier Reef.

"We really need to start carefully managing our reefs for both looking after habitat as well as trying to reduce fishing and that really means trying to reduce as many local stresses on the system as you can," he said.

"Because coral bleaching is caused by global warming, which is a global threat, it quite easy to stand back and say `there is nothing we can do then'.

"In reality if you can reduce as many of the local pressures and impacts on the coral reef system, it has got a much better chance of rebounding and recovering," Graham said.