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Red light negatively affects health of stony coral

Discussion in 'Lighting' started by jahmic, Mar 25, 2014.

  1. jahmic

    jahmic Shark M.A.S.C Club Member


    CLICK HERE TO READ THE FULL ARTICLE



    Summary:

    Using Philips LED lights, the researchers investigated how the SPS coral Stylophora pistillata would respond to light with varying intensity of blue and red light.* Dr. Wijgerde, a regular Advanced Aquarist contributor, describes the finding of his research for us: "For zooxanthellae growth, blue and red are co-dominant, whereas for chlorophyll a synthesis, red light seems to be dominant over blue, inhibiting chlorophyll a production. This is logical, as within the first 10 meters red light is present. Thus, the coral seems to use red light to detect a high irradiance environment, reducing chlorophyll a, and thus photosynthetic efficiency, prevent light damage."
    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.
    The paper's abstract (published in PLOS ONE) goes into more detail:

    Light spectrum plays a key role in the biology of symbiotic corals, with blue light resulting in higher coral growth, zooxanthellae density, chlorophyll a content and photosynthesis rates as compared to red light. However, it is still unclear whether these physiological processes are blue-enhanced or red-repressed. This study investigated the individual and combined effects of blue and red light on the health, zooxanthellae density, photophysiology and colouration of the scleractinian coral Stylophora pistillata over 6 weeks. Coral fragments were exposed to blue, red, and combined 50/50% blue red light, at two irradiance levels (128 and 256

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  2. jda123

    jda123 Barracuda M.A.S.C Club Member

    I think that most people who have been down on LEDs have known this for a long time... especially the old schoolers. This was a big theme in the 90s (or even earlier) when MH and Flourescent bulbs were being developed, and some of them remember. This is the main reason why while channels of LED are being run at 20-30% on some deeper stuff - the lagoonal or shallow stuff can reflect red better. Although I am totally down with the conclusions, I think that just using stylos was probably a limited test. This type of light is why stuff "melts."

    The crux is that you still need some of it to make the tank look "white" enough to human eyes.

    Yellow and green are about the same. I imagine that a similar study would find the same thing. Either can "melt" things too.

    After yellow and green revelation is going to be real UV from 350-400, which 20K radiums, 14K phoenix and even UVL Super Actinic give off.
     
  3. jahmic

    jahmic Shark M.A.S.C Club Member

    I haven't finished reading the full text article here: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092781

    ...but found this statement in their discussion pretty interesting:

    I think the article overall did a good job of providing a snapshot of some of the work previously published by Dana Riddle...that ones not exactly easy reading, but is full of information. It was interested to see everything applied in this experiment, but I totally agree...corals kept at shallow depth are more likely to thrive under red light and the results of this experiment don't apply to all stony corals. Testing one coral does limit the results a bit...just an interesting experiment.
     
    Last edited by a moderator: Mar 25, 2014
  4. jda123

    jda123 Barracuda M.A.S.C Club Member

    Dana Riddle (I think) did an article a number of years ago where he gets into reds, yellows and greens. It is very dense too and I don't have a link anymore, but it is really good. It gets into all light over 630, or so, having the same issues but to different degrees... but not from all sources.

    Amazingly, check out this chart for a 20K radium or 14K phoenix that shows a good amount of IR from 700 to 800, yet coral thrive under it. I realize that IR does not penetrate water too well, but what does that mean? 1M, 2M... our tanks are not all that deep... but regardless, those light still put out spectrum up to 700. I did not even stay at a Holiday Inn Express Last night, but, to me, there is something different about types of light that nobody understands yet... or are not telling. Either that, or the charts on some lights are boldface lies or the sensors don't measure them accurately.

    Figure 10 in this article shows many popular halide bulbs with output over 700:
    http://www.advancedaquarist.com/2004/2/aafeature2
     
    Last edited by a moderator: Mar 25, 2014
  5. GiraffeCat

    GiraffeCat Copepod M.A.S.C Club Member

    Interesting.. Thanks for the good find. Glad I decided to not include red in my home built lighting.

    Late,
    GC
     

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