Scientists have suspected for many years that warmer ocean temperatures were responsible for white syndrome, a coral-bleaching disease that is spreading across coral reefs. Since 1998, University of North Carolina researchers have tracked water temperature and the frequency of white syndrome across Australia’s Great Barrier Reef, the largest and most well known coral reef in the world.

According to this research study led by John Bruno, the University of North Carolina (Chapel Hill), “Our study suggests that, as global warming warms the oceans more and more, we could see more disease outbreaks and more severe ones.” [New Scientist, subscription required]

This study is the first to conclusively connect warmer ocean temperatures to the spreading of white syndrome.

Forty-eight reefs across 1,500 kilometers (900 miles) were studies by Bruno’s team for six years through ground and satellite data. Between 1998 and 2002, the frequency of white syndrome increased twenty fold. Adding to the severity of white syndrome is the situation when corals are more densely clumped together. In addition, the healthiest corals were attacked the most by the white syndrome disease.

White syndrome disease is a rapidly emerging coral reef killer. The cells within the coral, when confronted with the disease, activate a cellular process that acts like a self-destruct mechanism—what is called PCD (programmed cell death). The PCD is similar to a human’s immune system that is activated to fight infection. Thus, the disease is thought by scientists to come from within the coral, not from an outside invader.

Normally, PCD protects the coral by attacking viruses and bacterial. The PCD kills an area around the infected cells to make a barrier of dead cells to protect the healthy cells from further attack. However, something is going wrong with the process and the healthy cells are not being protected.

So far, the reason why this is happening is unknown.

Scientists are hoping to learn the cause of the white syndrome disease. This knowledge will help to protect reef-building corals in the future, sustain marine species, and provide a strong buffer zone of low-lying coastal areas.

The results of the study (“Stress and Coral Cover as Drivers of Coral Disease Outbreaks”) were published on May 8, 2007, in the online journal PLoS Biology. Bruno’s team includes Elizabeth R. Selig, Kenneth S. Casey, Cathie A. Page, Bette L. Willis, C. Drew Harvell, Hugh Sweatman, and Amy M. Melendy.

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