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Contact: Christine Payton Nov. 10, 2011
(337) 482-6397, payton@louisiana.edu
 
 
CAN CORAL REEFS TAKE THE HEAT?
 
With research funds from the National Science Foundation, a UL Lafayette biologist is studying coral samples from the Australia’s Great Barrier Reef. Dr. Mauricio Rodriquez-Lanetty wants to know how corals (and the microscopic algae that live inside them) are coping with increasing water temperatures and whether coral reefs may be able to survive global warming.

Rodriquez-Lanetty joined UL Lafayette in 2008 and established the Integrative Marine Genomics and Symbiosis laboratory, where he and his graduate students work. In 2009, he was awarded a three-year, $385,984 NSF grant.

Corals and algae have a symbiotic relationship. The corals become cellular hosts for the algae, which convert sunlight into sugars through photosynthesis. The corals use some of the sugar as food; meanwhile, their waste products provide food for the algae.

“ It’s a complex and fascinating relationship,” said Rodriquez-Lanetty in a recent interview.

That biological partnership has been a very successful one. Corals and algae form vast coral reefs, including the Great Barrier Reef, which stretches for thousands of miles off the northeast coast of Australia.

“ The Amazon rainforest and the Great Barrier Reef are the only living things visible from space,” said Rodriquez-Lanetty. “When you consider that the reef has been created by tiny organisms, interacting at the cellular level, it’s even more amazing.”

The partnership between the corals and algae is delicate one, dependent on just the right conditions, including clear, shallow water that is warm but not too warm. The optimum water temperature for shallow-water corals is between 79 and 81 degrees Fahrenheit.

“ In recent years, we’ve been seeing periods of elevated water temperature occur more frequently,” he said. Water that is too warm for too long produces stress in both the corals and algae. Sometimes, the corals expel the algae from their cells. When this happens, the corals starve to death. The end result is coral bleaching. Instead of a thriving habitat, stretches of underwater reef reveal the ghostly skeletons of former coral colonies.

Coral reefs are an important ecological and economic asset, he explained. Around the world, fisheries and tourism rely on the presence of healthy reefs. They are a source of biodiversity for pharmaceutical research, as well.

Last year, Rodriquez-Lanetty visited the Great Barrier Reef to collect samples of Acropora millepora, or staghorn coral. Working at the University of Queensland’s Heron Island Research Station, he transferred the corals to salt-water aquariums and began a series of experiments.

Some of the samples were held in tanks at 31 degrees Celsius (about 88 degrees Fahrenheit) for eight days. All the corals bleached and most of them died.

But another group fared much better. They were held for 10 days in water heated to 28 C (82 F) for 10 days, and then later exposed to the even warmer water for eight days. Those corals had greater survival rates.

This gradual exposure seems to have prompted a physiological adaptation response in the corals, said Rodriquez-Lanetty. The results were published online Oct. 5 in an international science journal, Proceedings of the Royal Society B: Biological Sciences.
Samples from the Barrier Reef expedition were frozen and transported to UL Lafayette.

Now he and his students are studying the genetic mechanisms in the corals that give them the ability to respond to temperature changes.

Rodriquez-Lanetty said this knowledge could eventually give scientists new tools to help coral reefs survive global warming.

“ By knowing which genes provide tolerance to heat, we may eventually be able to genetically manipulate corals, making them more resistant,” he said.
 
 
 
 
 
 
 
 
 
 
 

Document last revised Thursday, November 10, 2011 2:01 PM

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