A new extensive study conducted on Australia's Great Barrier Reef concluded that warmer oceans aggravate the incidence of a mysterious lethal disease in corals called white syndrome.

The 6-year study published on Tuesday in the Public Archive of Science details the significant link found between global warming, the rise in temperatures at oceans’ surface and the proliferation of the deadly white syndrome.

The study involved combined data coming from high-resolution satellite cameras (which have monitored oceans’ temperature) and from annual surveys of coral disease for 48 reefs.

The research found “a highly significant relationship between the frequencies of warm temperature anomalies and of white syndrome”, the latter being considered not only as a unique emergent disease, but perhaps as a group of diseases that might plague in the future the corals composing the Great Barrier Reef.

The direct link between the rise in temperatures and the outbreak of the white syndrome was demonstrated when scientists discovered that warm years have determined an increase in the pathogen’s spreading. The syndrome was found to have spurred in areas where corals were tightly packed and abundant, “suggesting an important role of host density as a threshold for outbreaks.”

Scientists conclude that the accelerated global warming observed in recent years might constitute in a risk factor for the health of the coral population, as warmer temperatures are likely to occur in most tropical oceans.

John F. Bruno, from the Department of Marine Sciences, The University of North Carolina and the leader of the experts, said: “we found for the first time that ocean temperature is a major driver of disease outbreaks on the Great Barrier Reef. And I think more surprisingly, we also found that coral cover, the percentage of the bottom that's covered with living corals, is also really important in driving those outbreaks. And ironically, it's the very healthiest reefs, the ones with the, the healthiest coral populations, where the disease outbreaks occur.”

The term ‘white-syndrome" (WS) was coined by the Australian Institute of Marine Science in recognition of the difficulty in diagnosing a disease(s) of unknown pathology based simply on visual field characters or signs. Typically WS is expressed on a coral as a white band sharply cutting across live coral tissue with a clear area of necrosis where the dead white coral skeleton and the living coral colony meet.

The progression of the band is generally slow enough that an area of coral with an increasing density of turf algae is seen, as you look further away from the freshly dead white part of the colony. Within this general pattern the symptoms can vary considerably depending on the progression of the disease and the amount of the colony it infects.