The Wildlife Conservation Society today released initial field observations that indicate that a dramatic rise in the surface temperature in Indonesian waters has resulted in a large-scale bleaching event that has devastated coral populations.

WCS’s Indonesia Program “Rapid Response Unit” of marine biologists was dispatched to investigate coral bleaching reported in May in Aceh–a province of Indonesia–located on the northern tip of the island of Sumatra. The initial survey carried out by the team revealed that over 60 percent of corals were bleached.

“Bleaching”– a whitening of corals that occurs when algae living within coral tissues are expelled – is an indication of stress caused by environmental triggers such as sea surface temperature fluctuations. Depending on many factors, bleached coral may recover over time or die.

Subsequent monitoring conducted by marine ecologists from WCS, James Cook University (Australia), and Syiah Kuala University (Indonesia) were completed in early August and revealed one of the most rapid and severe coral mortality events ever recorded. The scientists found that 80 percent of some species have died since the initial assessment and more colonies are expected to die within the next few months.