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OK its time for a new one. This weeks topic is Coral coloration, What makes the glow or take on such elaborate colors?? is it the Zoo, is it the pigentation?, Is it something else. What mekes them color up even more, is it the color of the light?

Lets hear your thoughts folks


Mike
 
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i think it is the zoanthele in relation to tthe lights, if you have a nice acro lower in the tank it will color but not as nicely as if it was more at the top. also thlighting itself imo plays a huge role the better the ligting the better the color. i know my awnser are childs play compared to when spanky or you other pros get in here but thisis what i know so this is what i say
:)
 

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I would say that it depends on the coral itself. My understanding is that some corals (especially the ones that are near the waters surface) use their pigments to filter out the UV light. I know there are other reasons, but I'll let the experts cover that while I go reread my books...again.

Great topic Mike. I hope I can learn some more on this.
 

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I think for me, what adds the most color is the acrylic paints I use. I esp love glow in the dark paint. ;)

Just kidding! I think a good healthy diet and lots of light and the zooanthellia will give it a great color.
 

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I don't know what makes them color up nicely but I do know that too much or too little actinic makes my tank look terrible. I had Red Sea 10K 175W mh (looked great), changed to Custom Sealife 10K 175W mh bulbs and it was too much blue (kinda washed everything out). Changed tanks went to Osram 150W 67K HQIs and 2 30W T-8 actinics, now the tank is brown. All corals especially the few sps frags I have seem to really like the new lights and my acro frag has finally gotten its purple tips back but I want different bulbs. My zoos seem to be changing to a brighter lime green now (2 months under the new lights). Also my BTA has almost doubled in size in the last 2 months. Can anyone reccommend a good looking 150W HQI bulb for my tank? (brand and Kelvin rating)
 
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well i was thinking about this last ight while i was sleeping! honestly i was, as we all know my favorite coral are the zoanthus species. and i know lighting plays a huge role as i can get frags place themn and have them morph totally depending on placement. and i can trade some away and get a pic of them 2 months later and they look nithing like the ones i sent out. so i do believe that lighting plays a significant role the coloration.
 

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mnreefman-could it also be that there are different species of zoothanlea (sp?) in these other tanks. the polyps acquire some of these other species and a have a different colour to them. i believe it is more due to the different colours of the different species of zoo. algae that give the corals the different colours. the different spectrums of light give competetive advatage to these different species.

my .02 guess on this.

G~
 
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this could be geoff, but the question was what causes this to show, and that would be the lights
:)
however the zoo gives them the color you see the lights cause the glow imo
 

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Geoff said:
mnreefman-could it also be that there are different species of zoothanlea (sp?) in these other tanks. the polyps acquire some of these other species and a have a different colour to them. i believe it is more due to the different colours of the different species of zoo. algae that give the corals the different colours. the different spectrums of light give competetive advatage to these different species.

my .02 guess on this.

G~
I read an article by Sanjay Joshi that stated that when a coral is placed in a tank it has to photoadapt to the various aspects of light: the intensity, spectral distribution and direction of light (this maybe obvious ?). "The basic adaptation mechanisms employed are various combinations of change in the chlorophyll content per unit surface area", *change in the number and size of zooxanthellae*, changes in coral morphology (the way they grow) to increase the surface area available for light capture, and changes in respiration rate (photosyntesis). It states that recent research is indicating that the corals may, in fact, have different types of zooxanthellae and the corals may be able to change the mix of the zooxanthellae as a photo adaptation response.
Another study indicated that differences in coloration were due to average pigment content in zooxanthellae, opposed to the density of zooxanthellae. Zooxanthellae would then react to the spectrum it was living under, showing pigments that are not absorbing energy (or light ????).
My guess is, this would be one of the reasons, why many hobbyists would claim that differences in coloration take place as the bulbs (light MHs) get older (spectrum shifts), or when a coral moves from one tank to another with different lights. Or why, poorly lit tanks show corals that look brown (more photosyntesis ??, higher zooxanthellae density, or busier zooxanthellae absorbing light ???).

Just an opinion...
 

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mnreefman said:
this could be geoff, but the question was what causes this to show, and that would be the lights
:)
ahh, the chicken and egg syndrome hits the reef discussion.:D

another idea is whether or not these colours are healthy for the "corals". just being argumentative here. maybe the brighter colours are a defense from really bright light. i think it is the browner colours that produce the most food for the thier hosts.

G~
 

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Master of Perplexity
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My humble observations

Okay, I've got a 250W 12,000K with 2-55W actinics and 2-55W 7100blues. Bought an acro colony that was very well developed, brown from staying under 2 VHO's at the lfs for months. My system is only 5 months old (I know, but he gave it to me for $15, claimed he couldn't sell it ) So I brought it home and put it in the bottom of the tank (70g-20"deep) After a week I put it top center. Slowly, over another week it began to fade to white. I knew it wasn't dead, just bleached cause there was color there, just not very bright. Last night, after lights out, I went back in for one last look and turned on the mh. As it fired and slowly came up in brightness, the color of the acro suddenly became this beautiful blue with pink tips, then as the light got brighter, it faded to its kinda bleached out, faint color. This morning I imagined that it had more color than it has had since it originally faded. So what's up?
 

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I think it has been stressed by change in light intensity.
This acro should be acclimated to that new light regime.
A coral that is adapted to lower light conditions may have a higher density of zooxanthellae or be capable of absorbing more energy. When you move that coral to an aquarium under intense light conditions, it is possible that the coral may become highly oxygenated during peak photosynthesis. The coral maybe facing oxygen poisoning.
What I've read in other threads is that you should start by placing your coral in a lower level in the tank where light is less intense (light intesity is reduced substantially with depth) and/or reduce the photoperiod if you see the coral react to light (in an undesirable manner). Give the coral time to adjust. I've read (again, I'm not talking from first hand experience) that corals are creatures with an incredible adaptability.
 

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yardboy-i think your acro bleached itself of its zooanthelae in order to get different species that prefers the lighting you have it in the tank. i think over the coming weeks the colour will get more pronounced as the zoo. reproduce in the acro, or the acro is able to acquire more from the tank.

placing the acro lower in the tank will help it get used to the lighting. you can then move it up in the tank over time.

G~
 

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Master of Perplexity
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Thanks guys. I agree that it was stressed from the light and I feel that it is on the way to recovery. I was just surprised that the colors seemed more intense at a lower light level. By the way, how does one determine how to set their photoperiod, given the light system they have? Right now, my mh is on for 6, off 2, on 5. My pc's are on for 14 hrs. That seems to be more than most others have theirs on, but in the tropics it's pretty intense for 12 hrs. a day. How is it determined?
 

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I'd try placing the coral near the bottom first, as suggested before. Check how it behaves. You may consider shortening photoperiod based on your observations.
 

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This is an observation I made during a bleaching event in my tank. I run 440w VHOs on a standard 55, but a while back, I was using cheap bulbs that were not full spectrum. Over a period of about 3-4 months, several of the corals in my tank-a flourescent green frogspawn, a green/brown/white devil's hand, colt, and green/brown/jade frilly 'shrooms-began to slowly lose their zooanthellas.

I didn't realize for some time just what was happening. All I noticed at first was that my corals were becoming so much more brilliant in color. The frilly 'shrooms and the devil's hand became brighter green over all, and, the frogspawn became the most stunning green I've ever seen in a coral. It wasn't until I noticed (finally) that the normally brown tentacals of the frogspawn were now totally transparent with the bright green sheen overlaying them, that realized that they had bleached. Once I corrected my lighting, all the corals made a complete recovery.

The bleaching event in my corals showed that (in some corals at least) the color, such as the brilliant flourescing greens, is part of the coral itself, and not of the zooanthellas. When the brown zoos return, the coral regains its brown color with the green as a transluscent overlay. Likewise, the color tips of some corals (such as my orange ricordia yuma and the 'spawns and torch corals) seems to be permanent and not affected by loss or change of zooanthellaes.
 

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Coral coloration is mainly a function of zooxanthellae photosynthetic pigments. Different zoox have different pigments at different amounts based on the conditions the coral is in (chlorophyll a, xanthophylls, accessory pigments, etc.). The pigments and sometimes their fluorescence (returning of electron to a lower energy state) are what we see.

UV radiation blocking pigments (mycosporine-like amino acids or MAA's) are implemented by the coral (not the algae) to protect the polyp and its symbiont. There are lots and lots of types of these pigments. In there reacting state (absorbing state), all of these pigments are clear. However, after being excited by UV, some of these MAA's fluoresce.

So coral coloration in captivity is all a complex system of checks and balances and a hat-tip to how adaptive the animals really are. Corals will change pigmentation with the slightest change in permanent lighting conditions, whether it be by denser stocks of photosynthetic pigments (brown/low light) or high fluorescence from certain MAA production.

Maybe more detail later when I'm not as tired... (yawn)
 
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