mechanism for coral to bleach under stress

[colourmop]

hello everyone:
I understand that corals and anemones will bleach (expels their photosynthetic algae) under stress such as high temp or low light, but could someone explain the mechanism of this behavior?(why would they do it and the steps) I've tried to search for it but I havent had any real results.
thanks very much

 

[mx#28]

Stress factors such as temperature and light disrupt the enzyme systems in
zooxanthellae that offer protection against oxygen toxicity. The relationship between the coral and its zooanthellae becomes unstable resulting in an overproduction of oxygen radicals and peroxide that can cause the coral to expel its algae in order to survive.
It has also been hypothesized that bleaching is an adaptive mechanism which allows the coral to be repopulated with a different, and more effective, type of zooxanthellae.
I've used a few words from Eric Borneman and a few other sources for assistance on this. I suggest you google "Coral Bleaching" among other search strings as well as check out a few good books - there's lots of good info and interesting theories on this matter.

 

[colourmop]

awesome thanks!! ^^