Using UV-A to promote pigmentation: advice on the subject

[BrainVat]

This picture was taken under a phillips 40w blacklight. UV-A stimulates defensive pigments that show nicely under 20k and 10k lighting. I speculate that supplementing a little extra UV-A each day results in greater expression of these defensive pigments by corals and/or their zooxanthellae.


http://www.canreef.com/photopost/dat...owing.jpg?9973

This LPS coral was mildly fluorescent when I first put the light over the tank. After about 30 minutes of UV-A, it glowed much more strongly. I suppose the effect is comparable to a tanning salon, except that corals have adapted far more numerous pigments for dealing with UV-A rays.

Also, an anemone did not fluoresce at all when first exposed to UV-A, but its tentacle tips began to fluoresce after less than an hour of exposure, and increased steadily in intensity for some time after that.

If you are planning on trying this, you must acclimate your corals to the UV-A by a tiny bit each day (20-30 mins), and should only try it on corals that are naturally adapted to make use of UV-A, such as deep-water LPS. If you turn on a blacklight over a coral and it does not fluoresce immediately or takes too long to adapt, chances are it is has little capacity to make use of this light and may be threatened. Even once a coral has produced the pigmentation needed to protect itself, you still will only provide a few hours of UV-A per day to maintain these pigments.

Realize that some corals do not produce these pigments purely for defense. The re-emission of light at a higher wavelength allows that light to be captured and used for photosynthetic purposes - perhaps even a driving force for the symbiosis between deep-water coral and their zooxanthellae. The former could produce the "UV harnessing pigment" while the latter catches reflected, lower-energy light and photosynthesizes.

Evidence for this comes from anecdotes in the hobby, where people have claimed to witness improved coloration on the switch to radium 20k bulbs, which emit stronger UV-A than other leading brands in the 20k range.

I am still in the process of experimenting and haven't decided whether to use this light regularly or not. It would have a strong impact on the selection of corals for my tank, which are mostly brains and hardy, deep-water LPS anyway.

-B.V.

[Gools]

I've also thought about this idea to. I know the reptile bulbs have UVA, and also UVB is there any difference?

[Quinster]

don't attinic 03 bulbs create the same type of spectrum?

[StirCrazy]

Originally Posted by Quinster

don't attinic 03 bulbs create the same type of spectrum?

nope just above the UV range.

Studies on using commercial Black lights have shown that a black light does not contain enuf UV-A to worry about as if it did, it would be banned from sale. Several people use "black lights" to enhance the color of there coral. what would be really good for your experiment is to take a picture of two identical coral side by side. then make it so one is exposed to UV and the other isn't but the water and other lighting is identical. then every month or two take them out of the water and take a pic side by side to see if the color has really changed in the corals.

Steve

[BrainVat]

Originally Posted by Quinster

don't attinic 03 bulbs create the same type of spectrum?

Actinic bulbs do generate UV, but less of it. I've also read reports that the tube itself contains a UV screen, but I don't have a reliable source for that.

Originally Posted by StirCrazy

Several people use "black lights" to enhance the color of there coral. what would be really good for your experiment is to take a picture of two identical coral side by side. then make it so one is exposed to UV and the other isn't but the water and other lighting is identical. then every month or two take them out of the water and take a pic side by side to see if the color has really changed in the corals.
Steve

I'd like to do a controlled experiment, but don't have the equipment for it. My observations here are purely FYI and shouldn't be taken as any kind of treatise on pigmentation. That said, the color changes in many of the corals are so noticeable that I discount personal bias. After several days of this "treatment", the corals retain part of their irridescence when under daylight and even a little when under 40w NO fluorescent light.

I've encountered other people's "experiments" on the web, but feel that since they lack controls and the aspect of double-blindedness, they should be interpreted as anecdotes like mine and not as actual science.

[StirCrazy]

If you pull the coral out of the water and look at it under normal lighting does it look any different?

this is the problem with using the lights that we do in our tanks. ( I am referring to real high K bulbs like radiums ) they make the color look wild when they are on but if you look at the coral under normal sunlight they are brown (talking acro's )

back to the black light it does react more intensely with the phosphorescent pigments in the coral and cause them to Fluoresce more intensely but I don't think it has the intensity needed to physically change the color of the coral.

Steve

[SeaHorse_Fanatic]

I placed a 75w Phillips Blacklight (thought it was only 30w). At first it didn't look like it was having much affect, but after several nights, my green swollen brain is a beautiful metallic green, whereas its always been a dirty green before.

JME

Anthony

My friend Matt had bought the bulb from HomeDepot in the fall but it didn't seem to do anything so we just put it away until I read this thread & thought, what the heck

[danny zubot]

Here's a question. Would exposing by bleached GBTA to low doses (15watts) of black light each day promote faster regrowth of zooanthalea?

[BrainVat]

I don't think it would. UV light taxes zooxanthellae by requiring them to produce these defensive pigments. This requires energy and nutrients and so would compete with growth and reproduction.

-B.V.

[sumpfinfishe]

I don't understand why one would want to put added stress on a coral by subjecting it to high doses of UV simply for increasing coloration