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Coral growth and light spectrum
- Thread starter cilyjr
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This is certainly a very uncertain topic. As many reefers have experienced, coral can experience loss of zooxanthellae when exposed to too much light, too little light, or a change in light spectrum. I'd be interested in seeing this experiment repeated with more traditional light positions (above the coral) or with different types of coral. Though the article is good food for thought, the results should be taken with a grain of salt as the sample is pretty minimal and there's relatively little control.
Almost all studies point to blue light being the most critical for coral growth and health. All other spectral bands are merely supplementary and may be necessary for the promotion of unique proteins/pigments in specific coral species.
Almost all studies point to blue light being the most critical for coral growth and health. All other spectral bands are merely supplementary and may be necessary for the promotion of unique proteins/pigments in specific coral species.
I always suspect that we generally over lighted our reef tanks for decades.
Now more and more studies support this view.l have been continuously lower lighting intensity for all the tanks I have and the growth of coral seems getting faster, at least not slowing down. My electricity bill has significantly drop as much as 30%.
Now more and more studies support this view.l have been continuously lower lighting intensity for all the tanks I have and the growth of coral seems getting faster, at least not slowing down. My electricity bill has significantly drop as much as 30%.
kotu100
You've been Ric'd
I want to bump this up as i feel there is some great discussion in here regarding coral growth and color under LED.
Has anyone heard of or read an experiment where a coral was grown with a single LED in a narrow color spectrum for a length of time (6 months?)
From what i've been reading i'm very curious as to how a coral would grow under an LED fixture using ONLY the uv-blue spectrum 400-480nm range. I believe that the coral will not only thrive but have excellent coloration as well.
From the studies done i can't see any concrete evidence that corals actually NEED anything in the spectrum above the 500nm range.
If you know of a study that proves this theory wrong please link me.
I'm just trying to learn.
Has anyone heard of or read an experiment where a coral was grown with a single LED in a narrow color spectrum for a length of time (6 months?)
From what i've been reading i'm very curious as to how a coral would grow under an LED fixture using ONLY the uv-blue spectrum 400-480nm range. I believe that the coral will not only thrive but have excellent coloration as well.
From the studies done i can't see any concrete evidence that corals actually NEED anything in the spectrum above the 500nm range.
If you know of a study that proves this theory wrong please link me.
I'm just trying to learn.
I don't know of any study that shows that coral absolutely needs light of specific spectrum outside of a broad blue. But... That isn't to say that stimulation with other wavelengths won't cause a change in pigmentation (not just how a coral looks under that specific light, but the pigments produced by that coral). It's complicated for sure.
One example to keep in mind is that we're talking about both the hosted Zooxanthellae and the coral tissue itself. To see how living things respond to light it may be better to look at some more well studied organisms like plants. 'The best-studied case of this type, and one that is a milestone in plant physiology, concerns seeds of the Grand Rapids variety of lettuce, which is stimulated to germination by red light (wavelength about 660 nanometres) but inhibited by “far-red” light (wavelength about 730 nanometres).' Similarly, red light of 660nm inhibits plant stem growth, while 730nm light reverses this effect. Both of these statements, however, are not true for ALL plants.
I'm not implying that these results can be applied directly to coral, but that it's complicated and we don't have all the info yet because the study of coral is not particularly profitable.
While coral may grow under an isolated spectrum I think it's safest to assume that exposing coral to the light they've evolved to use will yield the most "natural" growth. This becomes difficult as most reefers have both shallow water coral (relatively full spectrum) and deep water coral (almost exclusively deep blue) in the same tank.
Jury is still out until someone is willing to experiment a bit more
. Anyone want to run a blue only tank alongside a blue+white tank alongside a full spectrum tank? All with nearly identical coral frags, flow, and water parameters of course.
One example to keep in mind is that we're talking about both the hosted Zooxanthellae and the coral tissue itself. To see how living things respond to light it may be better to look at some more well studied organisms like plants. 'The best-studied case of this type, and one that is a milestone in plant physiology, concerns seeds of the Grand Rapids variety of lettuce, which is stimulated to germination by red light (wavelength about 660 nanometres) but inhibited by “far-red” light (wavelength about 730 nanometres).' Similarly, red light of 660nm inhibits plant stem growth, while 730nm light reverses this effect. Both of these statements, however, are not true for ALL plants.
I'm not implying that these results can be applied directly to coral, but that it's complicated and we don't have all the info yet because the study of coral is not particularly profitable.
While coral may grow under an isolated spectrum I think it's safest to assume that exposing coral to the light they've evolved to use will yield the most "natural" growth. This becomes difficult as most reefers have both shallow water coral (relatively full spectrum) and deep water coral (almost exclusively deep blue) in the same tank.
Jury is still out until someone is willing to experiment a bit more
. Anyone want to run a blue only tank alongside a blue+white tank alongside a full spectrum tank? All with nearly identical coral frags, flow, and water parameters of course.
OP
OP
cilyjr
Chris
Probably dong...lol
OP
OP
cilyjr
Chris
Ok so that would make since but it seems from stuff I have read that coral that survives drastic changes like being pulled out of the ocean and placed in a tank eventually adapt to the new lighting. So are we getting back to the idea that it doesn't necessarily matter a great deal what spectrum they are getting because they are going to adapt. And we are back to getting the light that is pleasing to our eye because the coral doesn't really care.
Interesting Study: http://www.advancedaquarist.com/blog/red-light-negatively-affects-health-of-stony-coral
"In layman's terms, the study reinforces the theory that corals use red light as their gauge for light intensity and regulates photosynthesis according to the amount of detected red light. With the popularity of red LEDs used in many modern lighting fixtures, reefkeepers should be conscientious of how much red light they use over their aquariums in light of this research. Note: red light is commonly found in proven lights such as Radium metal halides and numerous fluorescent bulbs as well as in wild reefs, so the idea is not that red light is necessarily harmful but that too much red light can have negative effects on how stony corals regulate photosynthesis."
"In layman's terms, the study reinforces the theory that corals use red light as their gauge for light intensity and regulates photosynthesis according to the amount of detected red light. With the popularity of red LEDs used in many modern lighting fixtures, reefkeepers should be conscientious of how much red light they use over their aquariums in light of this research. Note: red light is commonly found in proven lights such as Radium metal halides and numerous fluorescent bulbs as well as in wild reefs, so the idea is not that red light is necessarily harmful but that too much red light can have negative effects on how stony corals regulate photosynthesis."
Rmc i gave that article a read the other day. Pretty interesting and makes sense, the coral has no reason to regulate its algae levels using the spectrum that the algae best consumes. Another part of the spectrum such as red light would make just as good a meter since it is filtered so quickly with depth, it probably provides a more sensitive scale for ambient light strength. The sun being full spectrum also makes the use of red light in this fashion pretty plausible since the various parts of he spectrum would be equally present at the surface and as depth increases, red light would drop off rapidly while the intensity of the blue light would drop slowly. It is probably a great way for the coral to basically avoid a sunburn.
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It provides a great answer as to why many coral tend to bleach when LEDs are first introduced.
Lack of red spectrum > upregulation of photosynthesis > hypermetabolization > zooxanthellae flush
My takeaway was that a little red light is necessary, but that we should be careful to keep it low and proportional to the amount of blue/violet.
Lack of red spectrum > upregulation of photosynthesis > hypermetabolization > zooxanthellae flush
My takeaway was that a little red light is necessary, but that we should be careful to keep it low and proportional to the amount of blue/violet.
