brown corals

[reeflover1]

I have noticed lately that my shrooms and light polyps are getting a brown tinge to them
anyone have any ideas????

 

[neurotech]

It could be (4 month newbie here) that they are getting too much light. Too much light will increase the zooxanthellae they contain. Zooxanthellae produce brown pigment.

 

[davelin315]

I think it's a bit more complicated than too much light from what I have gathered from various discussions on maintaining desireable color and extension on corals (mostly on sps).

Here's what I think I understand about brown coloration. Brown results from brown zooxanthellae outcompeting the other colors. In some corals, the brown will take over because of inadequate lighting conditions for other colors of zooxanthellae, whether it be too much light burning them, or insufficient lighting causing them to not be able to compete. Another possibility is that certain nutrients in the water column might be aiding certain colors to come out (this I'm not sure of and don't know if I really understand the entire concept). You may get brown corals due to a sudden adjustment to the lighting and then they might recolor up. I have a staghorn that was greenish tinged, turned brown, and now is brown with bluish tips. The bluish tint appeared after I added 175W 10000K MHs to my system and was not there when I got the frag from under 400W MHs, nor was it there when I put it under my PCs.

In the end, it could just be an adjustment to your lighting, or your lighting could need to be replaced. What exactly is your lighting and how old is it? It could also be a factor of water quality, what are your parameters?

 

[neurotech]

I am pretty sure that zooxanthellae produce predominantly brown. The other pigments are actually part of the coral, not the symbiotic algae. Too much light, or a change to more light will usually cause increased brown. If too much, the coral attempts to re-establish homeostasis by expelling the zooxanthellae. When too much is released, it is called bleaching. The opposite is called coloring. I think many photosynthetic corals can achieve homeostasis over time. Others may alternetly color and bleach and need to be moved a bit lower or to the side.