Wednesday, June 18, 2014

Back to normal

After a week stuck inside while Tropical Storm Hagibis passed directly over Dongsha, we finally got back to our usual routine of research out on the reef. And when we got back out there, we were relieved to see that the corals are back to normal too.
The same coral colony bleached white on May 26 (top)
and recovered from bleaching on June 17 (bottom).

Corals that were bone-white a week ago were again green, a sure-fire sign that the corals are back to hosting photosynthetic symbionts. It appears the bleaching event is over at last.

While this is certainly good news, it doesn't mean all is well. We saw some mortality, so for some corals relief came too late. And the next bleaching event may be even more destructive.

Samples that we collected throughout the bleaching event will help us understand the resiliency of Dongsha corals. Using our coral cores, we can check how frequently bleaching occurs. We will also track how coral energetics (fat reserves, for example) changed as the corals bleached and then recovered. Further, we will see if the coral symbionts after the bleaching event are different than before bleaching. Certain "clades" of symbionts are more heat-tolerant than others, so the corals may have swapped out symbionts to better handle the heat.

- Tom DeCarlo
Joint Program in Oceanography
Woods Hole Oceanographic Institution

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