Mass Coral Bleaching in the Indian Ocean

Corals Adapting to Climate Change

May 22, 2015, 08:48 ET from Khaled bin Sultan Living Oceans Foundation

LANDOVER, Md., May 22, 2015 /PRNewswire-USNewswire/ -- Scientists with the Khaled bin Sultan Living Oceans Foundation (KSLOF) witnessed a massive coral bleaching event in the British Indian Ocean Territory (BIOT). They were there conducting research on the Chagos Archipelago for the world's largest coral reef survey and high-resolution mapping expedition, the Global Reef Expedition. This is the first reported bleaching in the Indian Ocean this year, which NOAA predicts will be a bad year for coral bleaching around the world.

During a period of warm weather and calm seas, corals became stressed and began to bleach. When the research mission started the corals appeared to be healthy, but within two weeks a dramatic transformation occurred and the corals began to bleach. The bleaching occurred quickly. Andrew Bruckner, Chief Scientist of KSLOF said he "never expected it to happen that fast." The scientists saw some corals turning bright white, while others turned cotton-candy shades of pink and blue in the process of loosing their symbiotic algae.

Long-term monitoring equipment indicates there have been high temperatures on the reefs in the past, for example in 1998. The team saw corals that were several hundred years old, which means that if they had previously bleached they have since recovered. As well as being able to tolerate these temperature fluctuations it appears that the corals are adapting to the rising sea temperature. Before the current bleaching event started the scientists saw healthy coral living in water that was warmer than the water that caused the mass bleaching in 1998.

But there could be even more to the adaptation. The spatial variability of the bleaching led the scientists to believe that a combination of light and temperature stress caused the mass bleaching. Some coral colonies did not bleach at all, scientists think that how they deal with the amount of light they are exposed to is the key to understanding their survival. "The symbiotic algae that live in the tissue are photosynthesizing - just like a plant does on land," Dr. Bruckner said. "If there is too much light, their photo systems break down and they produce these oxygen compounds that cause stress to the coral animal." In fact there is evidence that the corals that survive are now hosting more light tolerant varieties of their symbiotic algae.

The coral reefs of BIOT are extremely valuable and are "some of the healthiest coral reefs on the planet," says Professor Charles Sheppard, Chairman of the Chagos Conservation Trust.  "They are one of the world's last, intact reference sites as to what a coral reef should and could look like." 

Despite the severity and extent of the bleaching in BIOT, there is hope for a rapid recovery. Dr. Sheppard believes the reefs will recover quickly from bleaching because they haven't suffered from the stresses of overfishing, pollution, or any other significant human impact for the past 40 years. "Chagos is affected by warming episodes, and indeed is doing so right now, but without all the other local impacts, hopes are high that this large and magnificent archipelago will pull through."

About the Khaled bin Sultan Living Oceans Foundation:
The Khaled bin Sultan Living Oceans Foundation is conducting the world's largest coral reef survey and high resolution mapping expedition, the Global Reef Expedition. The Expedition is helping the Foundation realize its mission to provide science-based solutions to protect and restore ocean health. As part of its commitment to Science Without Borders®, Living Oceans Foundation provides data and information to organizations, governments, scientists, and local communities so that they can use knowledge to work toward sustainable ocean protection. For more information visit

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Photo credit: Khaled bin Sultan Living Oceans Foundation

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