PLoS Biol. 5, (6) e124 (2007)

Credit: AIMS

White syndrome is a disease fatal to Pacific reef-building corals. Although the disease has been linked to an increase in ocean temperature, it has a complex epidemiology and predicting its spread has proven difficult. John Bruno of the University of North Carolina in the USA and colleagues have now found the first conclusive evidence of a link between the frequency of warm years and the severity of the disease on corals along Australia's Great Barrier Reef.

Combining high-resolution satellite observations of ocean temperature with annual on-site epidemiological inspections, the researchers tracked white syndrome along 48 reefs over six years. They found that warmer ocean temperature was a necessary, but not sufficient, condition for the spread of the disease. When temperatures increased by at least 1 °C in 1 to 6 months, healthy reefs with a minimum of 50% living coral cover suffered more severe outbreaks than reefs with less living coral.

The greater concentration of fish and other species on healthy reefs may assist the spread of white syndrome, the researchers say. Weaker reefs attract far fewer fish and paradoxically escape such epidemics. Rising sea temperatures resulting from climate change could see diseases like white syndrome destroying reefs.