Sunday, July 15, 2007

Coping with Global Warming

Australian researchers have shown how some reef-building corals might protect themselves against the double threat of Global Warming and ozone depletion.

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," institute marine scientist Madeleine van Oppen said."Simply, when conditions warm the more heat-tolerant algae provide back-up, become more abundant. Some algal types impart greater resistance to environmental extremes."


Key species of coral can cross-breed, Australian research has found, fueling hope that coral reefs will be able to cope with climatic and environmental change.

The study of the Great Barrier Reef off northeastern Australia, by a team led by geneticist Dr Madeleine van Oppen, from the Australian Institute of Marine Science, has found evidence of cross-breeding in the major Acropora genus of coral.

Van Oppen said this week the new information indicates that coral species can develop a greater diversity of DNA that in turn should help them adapt to environmental changes that are threatening reefs worldwide.

The discovery also challenges the long-held belief that cross-breeding, or hybridisation, is mainly significant in the evolution of plants and not animals. Van Oppen said it has been difficult convincing the scientific community that corals do have the ability to cross-fertilise in nature.


Publishing in this week's issue of Nature, Dr Anya Salih and colleagues at the University of Sydney have found that certain varieties of corals use fluorescence to take the sting out of intense UV light, which otherwise acts together with warmer water temperatures to cause coral bleaching.
It had been observed for some time that corals fluoresced green when blue light was shone on them - but no one knew why.
"Our results show that in well-lit environments these fluorescent pigments act as 'sunscreens', protecting coral symbionts from photoinhibition by transforming excess light to wavelengths which are not absorbed by the algae and therefore will not damage them," say the researchers.

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