Why Blue Light?
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Scythanith
Premium Member
Maybe some pigments flouresce on the UV (purple, blue, etc) side of the light spectrum, making them "pop"? Some/most (???) marine life cannot see colours on the IR (red, yellow, orange, etc) side of the spectrum since it's naturally filtered out by seawater. The deeper you go the less red light can penetrate into the water... that's why there are more red fish the deeper you go, they seem invisible to most animals since red light isn't represented well. So maybe for corals to stand out they need to utilize the blue spectrum...maybe?
At lest this will stir the pot.
Scott
At lest this will stir the pot.
Scott
REEF-n-Chicago
New member
Everything Ive heard/read states that it is mostly for our pleasure only. The blue light makes everything look pretty! 
I do see what scythanith is saying about utilizing the blue spectrum and this might have some basis but I haven't heard much about it so.......
I do see what scythanith is saying about utilizing the blue spectrum and this might have some basis but I haven't heard much about it so.......
steven_dean17
New member
Scythanith is correct, the blue side of the spectrum is what is utilized by sea life. Red side is reflected off the surfface(for the most part) and this is why you get burned so qiuckly when your swimming.
glassbox-design
New member
being utilized and making colors pop are two different things
i'd suggest reading dana's articles in advanced aquarist. there is a 3 part series that goes in depth on this subject...
MCsaxmaster
New member
Wow, okey dokey there's a tad of misinformation above.
The zooxanthellae in corals use chlorophyll a as their primary light harvesting pigment, but have a variety of other accessory pigments which absorb and transfer light energy to chl a. Chl a absorbs strongly in the blue and red portions of the light spectrum. Chl c2 used by dinoflagellates absorbs strongest in the blue/cyan and red/orange, extending the range a bit. They also have several other pigments that absorb between the red and blue (~650 - 500 nm). All of this has absolutely nothing to do with coral coloration unless you're talking about brownish shades. Zooxanthellae, with their various pigments absorbing in the above wavelengths, look brown.
Corals produce a variety of colorful proteins. None of these have anything to do with blocking UV and do not interact with UV at all. Please for the love of goodness do not equate coral pigments to UV light--there is no relation between the two. Some of these pigments likely protect zooxanthellae from too much light by absorbing it and either reflecting it or fluorescing. Others probably have a function completely separate from their effects on light, but nonetheless they just so happen to absorb/reflect/fluoresce.
Many fluorescent pigments are some derivation of green fluorescent protein, GFP, and GFP absorbs in the blue. If you change the structure of the protein a bit you can modify its absorption wavelengths and emission wavelengths. So, normal GFP absorbs in the blue and fluoresces green. Modify it a bit and it will absorb in the cyan and fluoresce yellow. Lots of non-fluorescent proteins are similar to GFP in structure too. If they absorb in the green (and reflect blue and red) they look purple. If they absorb in the green and red they look blue. If they absorb in the blue and green they look red. You get the idea.
Chris
The zooxanthellae in corals use chlorophyll a as their primary light harvesting pigment, but have a variety of other accessory pigments which absorb and transfer light energy to chl a. Chl a absorbs strongly in the blue and red portions of the light spectrum. Chl c2 used by dinoflagellates absorbs strongest in the blue/cyan and red/orange, extending the range a bit. They also have several other pigments that absorb between the red and blue (~650 - 500 nm). All of this has absolutely nothing to do with coral coloration unless you're talking about brownish shades. Zooxanthellae, with their various pigments absorbing in the above wavelengths, look brown.
Corals produce a variety of colorful proteins. None of these have anything to do with blocking UV and do not interact with UV at all. Please for the love of goodness do not equate coral pigments to UV light--there is no relation between the two. Some of these pigments likely protect zooxanthellae from too much light by absorbing it and either reflecting it or fluorescing. Others probably have a function completely separate from their effects on light, but nonetheless they just so happen to absorb/reflect/fluoresce.
Many fluorescent pigments are some derivation of green fluorescent protein, GFP, and GFP absorbs in the blue. If you change the structure of the protein a bit you can modify its absorption wavelengths and emission wavelengths. So, normal GFP absorbs in the blue and fluoresces green. Modify it a bit and it will absorb in the cyan and fluoresce yellow. Lots of non-fluorescent proteins are similar to GFP in structure too. If they absorb in the green (and reflect blue and red) they look purple. If they absorb in the green and red they look blue. If they absorb in the blue and green they look red. You get the idea.
Chris
killagoby
New member
One of the coolest things I've ever seen was when I took a submarine ride in Hawaii. I have a tribal tatoo band around my arm that is red and black and around 3 inches thick. When we got down deep enough the water had filtered all of the red out of the color spectrum. My band looked solid black.
stony_corals
New member
RC should sticky this... This may reduce the "what bulbs to make my colors pop" or "how can I color up my corals"...
greenbean36191
Premium Member
zoh-zan-thel-ee
MCsaxmaster
New member
If it takes supplemental lighting in a greenhouse to get the corals to become colorful, then they aren't getting enough visible light. UV light has nothing to do with it. If folks with UV-blocking glass need more supplemental lighting than those without UV-shields then either the UV shield is blocking out a lot of light (e.g., frosting the glass) or it is coincidental. Most of these pigments absorb very little UV light, and there is no reason to think that they are produced to absorb any of the tiny amount of UV that they might. There simply is no relation between UV and the production or expression of pretty coral pigments. Unfortunately, thinking that there is some sort of relationship could certainly lead to a lot of dead corals overexposed to UV that did nothing but harm.
Chris
musty baby
New member
MCsaxmaster, do you happen to know of literature stating that the presence/intensity of UV light has no effect on pigment production/concentration?
There have been multiple articles that state UV does very little.
http://www.advancedaquarist.com/2007/2/aafeature#h2
http://www.reefs.org/library/aquarium_net/1298/1298_2.html
Dana Riddle
MCsaxmaster isn't pulling this out of his hat, this is common knowledge in the hobby. Of course common knowledge isn't alway correct.
http://www.advancedaquarist.com/2007/2/aafeature#h2
http://www.reefs.org/library/aquarium_net/1298/1298_2.html
Dana Riddle
MCsaxmaster isn't pulling this out of his hat, this is common knowledge in the hobby. Of course common knowledge isn't alway correct.
MCsaxmaster
New member
I've never spoken with Anthony about this. I'd be happy to talk with him and anyone about this topic though.
Experience growing corals does not make GFP-like proteins absorb significant amounts of UV. Experience in this case is completely meaningless. We are talking about a measurable physical property. Likewise, a person could have thousands of hours of flight time, but there is no way they are going to get a plane without wings to fly. A person can grow corals for decades, but that doesn't mean that GFP-like proteins are produced to deal with UV. They are not.
I've been growing corals for a bit more than 7 years now.
Chris
MCsaxmaster
New member
Essentially all of it suggests that these proteins don't have a role in shielding against UV. They simply don't absorb much UV, hence they physically cannot work as a UV screen. The pigments also tend to vary with the amount of visible light, not necessarily UV, though the two may covary in the field.
The one exception may be GFP which looks to be related to reducing oxidative stress, and just so happens to fluoresce green. In other words, the fact that it interacts with light is a harmless side effect of its structure. GFP doesn't absorb significant amounts of UV, so it isn't acting as a UV shield, but it does tend to be expressed more in organisms undergoing oxidative stress and in many non-photosynthetic organisms. It was recently found in Amphioxis, for example.
See work by Salih, Dove, Kawaguti, etc.
Chris
http://forum.marinedepot.com/Topic33101-13-4.aspx
The folks having trouble with browning corals did not do their homework. The problem is their sheeting or glazing (not to mention that apparent lack of understanding for principal mechanisms for coral pigmentation). There is no easy answer here either... their expectations in a GH are about as unrealistic as their expectations in aquaria when they mix corals from drastically different parts of the reef. There is no way you can expect a Euphylliid from 60ft that mfgs FPs to capture/retain weak light to be as colorful in the same tank as an Acroporid from 10 ft of water that mfgs FPs to reflect light. It may be impossible to get both to have optimal color under standardized lighting (UV blocked no less).
There is no secret why blue bubble corals turn brown under bright(er) aquarium lights... and why electric colored shallow water sps turn brown under weaker captive lighting (UV blocking and total light altering/reducing) sheeting for the GH in this case.
The matter is made worse by these cheap hobby greenhouses having really poor quality sheeting/glazing.
The folks with brown corals frankly got what they paid for (low investment in their education... low investment in their facility). I mean that literally... not as a slight (please don't take it out of context - to all).
.
Anthony Calfo
The folks having trouble with browning corals did not do their homework. The problem is their sheeting or glazing (not to mention that apparent lack of understanding for principal mechanisms for coral pigmentation). There is no easy answer here either... their expectations in a GH are about as unrealistic as their expectations in aquaria when they mix corals from drastically different parts of the reef. There is no way you can expect a Euphylliid from 60ft that mfgs FPs to capture/retain weak light to be as colorful in the same tank as an Acroporid from 10 ft of water that mfgs FPs to reflect light. It may be impossible to get both to have optimal color under standardized lighting (UV blocked no less).
There is no secret why blue bubble corals turn brown under bright(er) aquarium lights... and why electric colored shallow water sps turn brown under weaker captive lighting (UV blocking and total light altering/reducing) sheeting for the GH in this case.
The matter is made worse by these cheap hobby greenhouses having really poor quality sheeting/glazing.
The folks with brown corals frankly got what they paid for (low investment in their education... low investment in their facility). I mean that literally... not as a slight (please don't take it out of context - to all).
.
Anthony Calfo
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