Coral bleaching

[florida joe]

Not wanting to highjack another thread I decided to start this one and post some info on coral bleaching.
First it is important to understand that bleaching is not Rapid Tissue Necrosis
Bleaching is defined as the mass expulsion of zooxanthellae or their pigments from the coral, which typically appear white. Bleached coral is still ALIVE, albeit with translucent tissue.
What can lead to their demise though is the fact that they become nutritionally compromised due to the lack of energy provided by a full complement of zooxanthellae. This lack of energy causes the bleached coral to begin metabolizing their lipid reserves with the metabolizing comes a reduction in mucus production, which in turn reduces its resistance to disease
Coral bleaching is very common simply because of the many agents or factors that can cause them to bleach
Bacteria, chemicals, cilates, coccideans, darkness, fungi, heavy metals, high temp, hypersalinity, hyposalinity, lack of water movment, light, noxious agents, medications, physical stress, starvation, and temp changes are just a few of them
I hope this thread opens up a good Discussion as this is something we all will or have encountered in keeping corals

 

[nano reefer]

thanks joe!

 

[cmaxwell39]

Good thread Joe. Shows that there are many factors to bleaching and it is not always the assumed culprit of light.
I do have a question. Is there any good way of determing the cause of bleaching so that steps can be taken to correct the situation, or is it just trial and error? I know that sometimes you won't ever be able to tell, but what are the steps that peeple use to try and save a coral that is bleaching or has bleached?

 

[beth]

Here's a decent article on the bleaching of coral reefs.
http://www.marinebiology.org/coralbleaching.htm

 

[privatejoker]

To save the bleached out corals I move them to less or more flow which ever is the opposite of where it is. I've taken out bulbs from my light fixture and that seemed to help. It is trial and error for the most part. Some corals do well in my tank and then I give them to a fellow reefer and they die, don't know why but they can be picky.