Climate change threatens reef fish

Climate change threatens to devastate coral reef fish populations and increase the likelihood of fishery collapses, Australian researchers warned Monday.

Coral reefs' vulnerability to global warming has already been established by researchers, but the fish living in the reefs are also at risk, James Cook University's Centre for Excellence in Coral Reef Studies found.

"We have already seen episodes of mass die-off of corals as a result of warmer waters associated with global warming, the problem for specialist coral fish is that when the corals die, the fish have nowhere else to go," the centre's Philip Munday said.

Munday said there were some 4,000 fish species living in or around coral reefs, providing livelihoods and a major source of sustenance to an estimated 200 million people worldwide.

He said the problem with coral fish stemmed from the fact that when they bred, their eggs were swept out to sea and the baby fish then swam back to resettle on the reefs.

"If reefs have been extensively damaged or the composition of their corals altered due to global warming impacts, this process of re-stocking the reefs with fish may be disrupted," he said.

"At the same time, the baby fish are likely to be affected by changes in water temperature and the acidification of the oceans."

Munday said some fish may migrate to cooler waters if temperatures around their reefs became too warm.

But he said this was not an option in Australia's Great Barrier Reef because there was nowhere for new coral to grow in the deep waters to the south of the giant reef, regarded by scientists as the world's largest living organism.

"There is really nowhere for coral reefs and their associated fish communities to expand," he said.

"Effectively, this means that some coral reef fish species will be squeezed by rising water temperatures into smaller and smaller areas, making them more susceptible to disturbances such as coral bleaching and increasingly vulnerable to fishing and other forms of human activity."
The coral centre's paper, a synthesis of previous research, was published in the journal "Fish and Fisheries" and will discussed at an international symposium on coral reefs in Florida next month.

Agence France-Presse - 6/16/2008 9:36 AM GMT