An idea to save coral reefs from climate change takes a step forward

BLEACHING IS BAD for coral. It happens when heat-stressed polyps, the sessile animals that construct coral reefs, eject the photosynthetic algae which usually reside within them. These algae are symbionts, providing nutrients to their hosts in return for shelter, so losing them is harmful to polyps and often results in their death. The higher temperatures brought about by global warming have therefore led to worries that more frequent episodes of bleaching might result in the loss of entire reefs.Some of these symbiotic arrangements between alga and animal are, however, more heat-sensitive than others. It might therefore be possible to save reefs by seeding them with heat-resistant symbioses. As temperatures rose, these biological partnerships would spread and the reef they had been transplanted to would survive. Two researchers studying this idea are Megan Morikawa and Stephen Palumbi of Stanford University, in California. And they have just published a paper in the which suggests that it might work.