Coral "shuffle" helps reefs survive warmer world-study

SYDNEY, July 13 (Reuters) Australia's Great Barrier Reef might be able to survive warming sea temperatures, as a result of global warming, better than first thought because some coral algae are more heat tolerant, Australian scientists said.

Coral geneticists from the Australian Institute of Marine Science have found that many corals store several types of algae, which can improve their capacity to cope with warmer water.

''This work shatters the popular view that only a small percentage of corals have the potential to respond to warmer conditions by shuffling live-in algal partners,'' said institute marine scientist Madeleine van Oppen.

''Simply, when conditions warm the more heat-tolerant algae provide back-up, become more abundant. Some algal types impart greater resistance to environmental extremes,'' van Oppen said in a statement received today.

Since the 1980s, reefs around the world have been devastated by coral bleaching, where temperature increases of just 1 degree Celsius can cause coral animals to expel the photosynthetic algae that keep them supplied with nutrients.

Numerous scientific studies have warned that global warming of the ocean was threatening the very existance of reefs, such as the Great Barrier Reef.

The Australian scientists said their study had found that coral has the ability to ''shuffle'' the algae, maximising nutrients depending on water temperature. They discovered heat-resistant algae by examining the DNA of different types of coral.

But many marine scientists have argued that ''back-up'' algae were infrequent because of the small number of corals that were shown to host several types of algae.

''The potential for this hidden back-up type (algae) to step in and provide nutrition to coral during heat stress is far greater than currently thought,'' said Jos Mieog, a PhD student involved in the coral study.

The Australian scientists said this ''shuffle'' ability might explain why coral reefs have been able to survive for thousands of years during various climate changes.

''This flexibility discovered in our research is important in understanding the past evolutionary success of these coral species and their future survival capacity in the face of a changing climate,'' said van Oppen.

REUTERS SW DS1135