Stanford, CA Coral reefs are tremendously important for ocean biodiversity, as well as for the economic and aesthetic value they provide to their surrounding communities. Unfortunately they have been in great decline in recent years, much of it due to the effects of global climate change. One such effect, called bleaching, occurs when the symbiotic algae that are essential for providing nutrients to the coral either lose their identifying photosynthetic pigmentation and their ability to perform photosynthesis or disappear entirely from the coral's tissue. Without a healthy population of these algae, the coral cannot survive.
There has been much attention given to the environmental conditions that trigger a reef's demise due to bleaching, but little is certain about the precise cellular and molecular mechanisms of the bleaching process. New research from Carnegie's Arthur Grossman brings into question the prevailing theory for how bleaching occurs on a molecular level. It is published in Current Biology.
Photosynthesis, the process by which plants, algae, and select bacteria convert the sun's light energy into chemical energy, takes place in a cellular organelle called the chloroplast. It has been theorized that the major cause of bleaching is the result of chloroplast damage due to heat stress, which results in the production of toxic, highly reactive oxygen molecules during photosynthesis.
Grossman and his teamled by Carnegie's Dimitri Tolleter and in collaboration with John Pringle and Steve Palumbi of Stanford Universitydemonstrated that bleaching still occurs if the algae are heat stressed in the dark, when the photosynthetic machinery is shut off. This is surprising since it means that toxic oxygen molecules formed in heat-damaged chloroplasts during photosynthetic reactions during the light are likely not the major culprits that cause bleaching.
Therefore other, as yet unexplored, mechanisms for bleaching must
|Contact: Arthur Grossman|