Australian corals might migrate south: scientists

The Age 2 Jan 08;

Global warming may result in tropical corals migrating south, Australian scientists say.

The Centre of Excellence for Coral Reef Studies says the western seaboard between Perth and Geraldton could end up with coral reefs as rich and varied as the celebrated reefs of Ningaloo in the north-west.

The centre's researcher, Professor John Pandolfi, and Professor Benjamin Greenstein of Cornell College, Iowa, USA, worked from fossil evidence of what happened in West Australian waters during a warm phase in the global climate 125,000 years ago.

Their findings, published in the international journal Global Change Biology, concluded that tropical corals could soon head south once more to escape warming oceans.

"Back then there used to be rich coral reefs dotted all along the WA coastline, from south of Perth to north of Dampier," Prof Pandolfi said in a statement.

"When the seas cooled with the onset of the most recent ice age, many of the corals contracted north."

The result was that there are two distinct coral communities - the rich and beautiful one capable of reef growth from places like Ningaloo, and a far simpler community with fewer species scattered on rocky outcrops in the cooler waters of the south.

Prof Pandolfi said that with oceans warming again due to the greenhouse effect, the rich, diverse northern corals are likely to spread south again, travelling on the Leeuwin current, in search of places to survive global warming and avoid impacts such as bleaching and coral disease which occur when tropical waters warm too much for them to tolerate.

He said WA had suitable shallow habitats for tropical corals to settle in, whereas south of the Great Barrier Reef there were few suitable areas for corals to move south.

"The water is mostly too deep," Prof Pandolfi said.