July 9, 2006, Updated September 14, 2012

Sensitive to the slightest amount of change in seawater temperature, one-third of the world’s coral reefs have died. Coral reefs are sick and dying. Global warming is mainly to blame, according to Tel Aviv University (TAU) Professors Yosi Loya and Eugene Rosenberg.

This dynamic duo is strapping on their flippers and getting ready to hit the sea: they have been assigned a lofty mission by the World Bank to turn around the spiral of destruction. In conjunction with about 60 other experts in the world, they are sharing a $21 million fund as part of the International Coral Reef Initiative, designed to research coral and build a plan of action that will be followed by ocean stewards around the world.

Rosenberg and Loya know that bacteria are killing corals. Global warming and pollution are exaggerating this effect at an unprecedented rate. Today, one-third of the world’s coral reefs have died, says Loya, who explains that coral reefs are sensitive to the slightest amount of change in seawater temperature. Rosenberg adds that increased temperatures cause certain bacteria to become more virulent.

The World Bank chose the two TAU experts to form their international reef team, both because Loya and Rosenberg are leaders in their respective fields, coral biology and coral microbiology, and because they have a longstanding tradition of taking basic research, and combining it with environmental science to make real-world solutions that leap out of the laboratory.

Professor Loya, a zoologist at the George S. Wise Faculty of Life Sciences, has worked on the community structure and species diversity of Red Sea reefs. He formed the foundation for many modern reef studies and sampling methods that are used worldwide today. Loya has pioneered investigations of reef-communities from the native Red Sea corals in Israel to the Great Barrier Reef. More recently, he has contributed to understanding the effects of chronic pollution and how interactions between elevated sea temperature and bacterial disease affects Mediterranean corals.

Professor Rosenberg, from the Molecular Microbiology and Biotechnology Department, has made advances in environmental technologies, such commercializing bacteria that consumes crude oil. He has written numerous books on how to use microorganisms to combat pollution. In recent years he has demonstrated that certain bacteria are responsible for coral bleaching.

“The World Bank assigned five different groups of experts on different aspects of the problem from coral diseases, bleaching of coral reefs and restoration initiatives and they selected the best people in the world,” said Loya, “There is power in producing better understanding in pure research on why the corals are dying.”

Acting as underwater sleuths, the scientists are involved in figuring out an action plan that can take effect before Global warming damage is irreversible. To formulate the plan, they meet with their teams around the world and together devise a strategy for managers at the local level to follow. Whether it is the Philippines, India, or Israel, researchers are making sure both developed and developing countries have access to the same coral reef management tools.

“A coral reef is like an underwater rainforest and the world’s most important indicator system,” says Professor Loya. “I have been working on coral reefs for forty years and corals are the most complex and diverse system in the marine environment. The only terrestrial ecosystem that can come close to it in its complexity is a rainforest.”

Coral health is valued as an important yardstick for assessing environmental degradation due to Global warming . Known as an indicator species, like amphibians are in terrestrial ecosystems, coral reefs are sensitive to environmental disturbances, man-made or natural, even before the extent of the damage can be fully known.

“You hear a lot about global change and the warming of planet earth,” says Loya. “Coral reefs are sensitive to differences in temperature and are used to growing in a stable environment. When they don’t have that, they die. Corals thrive within a temperature window of 20-26 degrees centigrade. Two degrees more in temperature is a disaster for coral reefs. In the last 10-15 years, there are more and more reports around the world of coral reefs, which are dying. They are the first to respond to change.”

Coral reefs are colorful, rock-like structures built by ocean animals called corals. The living animals are about an inch long and live on the sea floor by attaching themselves to the limestone carcasses of their dead ancestors. Thousands and millions of years later, the layers of living and dead corals form a large coral structure called a reef which in turn becomes an attractive homestead for thousands of other ocean animals and plants.

“Everyone talks about sick corals and describes the number of infectious diseases that they are subjected to,” says Rosenberg, who has decided to take a unique approach and looks at corals as though they are terrestrial animal. “In most animal systems, infectious disease is protected by various mechanisms,” he explains. “If you sneeze, you cover your face or you clean up water a supply so the disease won’t be transmitted.

“I am studying what to do when corals sneeze,” he says, noting that a distinctive coral killer, a species bacterium he calls a pathogen, is becoming more virulent as the globe heats up. The bacteria prey on the algae living in the coral and since these algae are the primary nutrient source for corals, without them, corals die.

“If we stop the transmission of the bacteria to the algae, we can control the disease and coral death,” affirms Rosenberg. It is a simple answer to a big problem, but like a drug-developer seeking a cure for a disease, he says, a practical solution to stopping the transmission is in the works.

Rosenberg is collaborating with five other top researchers from around the globe working specifically on coral disease. The funding gets channeled to TAU graduate students too: the Red Sea coral reefs’ proximity to Tel Aviv University means that graduate students can make their country a classroom. The university is also an attractive hub for international students and visiting professors working in marine microbial ecology.

The Red Sea coral reef is arguably one of the most important reefs in the world in terms of species diversity and size; it is also one of the most northerly corals in the world. At a junction of three countries Israel, Egypt and Jordan, it is in peril: local pollution and the effects of global warming are taking its toll.

Coral health can be preserved only if some of the world’s greatest polluters clean up their act, Loya believes, “Reefs can be restocked, the local pollution can be cleaned up, but the only long-lasting solution to saving the corals is to stop global warming through political action in all of the world’s governments.”

On the local side, one of Loya’s battles is trying to get Israeli fish farms in Eilat to stop polluting the water. In the lab he is using contemporary and fossil corals to build predictive models concerned with global climate change.

The positive side to the coral story is that the World Bank, an influential force for change, is now involved in the fight against global warming. The international coral initiatives that TAU professors are spearheading are supported by similar efforts by top-notch scientists from other institutions such as Scripps and Harvard.

“There is power in producing better understanding of global warming ,” says Loya, “But as for a real-world solution to dying reefs and global warming , we need to decrease the emission of greenhouse gases today.”

Loya’s commitment to saving the environment has had a great impact on his colleague Rosenberg. “Loya was my biggest influence,” he says. The two have co-edited a book Coral Health and Disease.

Rosenberg doesn’t have a diving license and only occasionally snorkels. His attitude is positive and directed to humanity’s ability to change the current situation. “I only snorkel when I have to,” says Rosenberg, “The last time was at the Great Barrier Reef and they had to throw me a life vest in the end. Today, I work mostly in the lab and my students dive and bring back the coral. I smoke cigars and I think,” quips Rosenberg.

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