Water temperatures reaching as high as 93 degrees Fahrenheit in Southeast Asia’s Andamann Sea have led to a large die-off of coral reef off the coast of Indonesia, the Wildlife Conservation Society (WCS) reported earlier this week.
The abnormally high ocean temperatures lasted for about a month, the report said. Surveys conducted in May, when temperatures started to peak, revealed that more than 60 percent of corals off the coast of the Aceh province in Indonesia had bleached an subsequently died.
Subsequent monitoring by marine ecologists earlier this month revealed that up to 80 percent of some coral species had died since the first assessment in May – one of the most sudden and severe coral die-offs ever recorded. More colonies of coral are expected to bleach and die in the coming months, said Caleb McClennen, the WCS director of marine conservation.
The mortality rate is incredibly high for this type of bleaching,” said McClennen. “Frequently, corals will bleach and recover, but that is not happening here.”
Coral bleaching happens when algae that normally lives within the coral is ejected. It is the algae that gives healthy coral their vibrant colors. Bleaching is an indication of environmental stress, such as variations and warming of sea surface temperatures.
The research report released by the WCS this week is based on surveys conducted with scientists from James Cook University in Australia and Syiah Kuala University in Indonesia.
The massive bleaching event was a surprise for researchers, McClennen said. Many of the now dead coral had survived significant environmental stresses in the past, including the 2004 Indian Ocean tsunami.
When we went and did surveys in early 2005, it turned out the corals were resilient to the impacts of the tsunami,” he said. “Local fishing, river runoff and poor management were greater causes of localized coral decline. So the region has quite robust coral reef populations. We thought they would be quite resilient to these types of impacts.”
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