Effects Of Narrow Bandwidth Light Sources

Discussion in 'Lighting' started by scubaninja, 21 Apr 2012.

  1. scubaninja

    scubaninja

    Joined:
    20 Jul 2008
    Posts:
    6,739
    Likes Received:
    21
    Location:
    Durban
    Effects Of Narrow Bandwidth Light Sources On Coral Host And Zooxanthellae Pigments

    I've been prowling the internet for a while trying to find out what wavelength (colour) combination of lights would be most efficient for use on our tanks. What I was looking for was the effect of specific bandwidths on coral growth and colour. I wanted to read it myself from the source to see all the bits that people usually leave out. Of all the articles I've come across, this one ( Feature Article: Effects Of Narrow Bandwidth Light Sources On Coral Host And Zooxanthellae Pigments )was the most enlightening. Some of it is quite technical and confusing, but eventually with a better understanding on how it all works and what I've learned so far I've pulled the main points out to save others the trouble. They may not be ALL the points from the articles, but the ones I think are most prominent to what we are looking for. If you feel I have missed some out please feel free to add them :)



    1. Zooxanthellae are symbiotic algae that live inside a corals tissue and they control the pigment of the coral. SPS are the most prominent example.The coral will alter the amount of zooxanthellae in their tissue to reflect(protect themselves from) the light intensity. It is usually some combination of the colour of the light that is shining on them as they are trying to reflect a portion of that wavelength.
    2. There are two photosynthetic processes happening inside the corals, Photosystem I(chlorophyll produces a reductant) and II(chlorophyll produces an oxidant) which try to balance out photosynthesis in the coral. Red light helps the 'road' between P2 to P1 and blue(more violet really) light helps the road between P1 to P2.
    3. Red is light is about 36% more efficient at penetrating water than blue and, for the same initial intensity as blue, is more likely to bleach your corals. So this means that for the same intensity to reach your corals(equal road widths between P1 and P2) you must have less red than blue to start with.
    4. The bleaching of the coral in the experiment was attributed to having too much of one photosystem leading to a 'blockage'(if you stick with the highway analogy) and eventually death of that part if the bias cannot be corrected.
    5. The light absorption of the two clorophylls peak at certain wavelengths. Chlorophyll-a peaks at ~430nm and again at ~660nm, Chlorophyll-b peaks at ~455nm and ~640nm.
    6. As far as the article goes, the effect of green and yellow on colour is not confirmed. However if you look at the spectral distribution of the white lights we use, there is usually a significant portion of light intensity offered in their spectrum range not to warrant the need to supplement them in lighting.


    So this all brings me to the final point-"What colour combination do I use?" Well to start off, using lights with peaks in the ranges where the greatest cholorphyll absorption happens is a good start. Most actinics(blue lights) contain some of this wavelength and the white lights (around 10000k) contain a peak of both blue and red in differing amounts. So a combination of the proper white and blue(actinics) will be able to deliver the spectrums needed for healthy coral growth. The intensity of both would be determined by your aquarium depth as well as your choice colour of the tank.


    I hope this is has been helpful:thumbup:
    Personally I go for a tank that only has a slight blue tint ;)
     
  2. AdS Guest




    to hide all adverts.
  3. belindamotion

    belindamotion Google Master

    Joined:
    24 Jan 2011
    Posts:
    4,803
    Likes Received:
    134
    Location:
    Pinetown,South Africa(KZN)
    Last edited: 22 Apr 2012
  4. Jamie@Vertex

    Jamie@Vertex

    Joined:
    6 Aug 2011
    Posts:
    189
    Likes Received:
    17
    Location:
    Germany



    This is not quite correct. Zooxanthellae have no direct effect on pigment, other than them acting as a brown pigment, when present in high amounts. The zooxanthellae do not protect a coral from light. It is thought that pigments do. Under too much PAR zooxanthellae actually shrink in size and may die.



    Corals have little control over their zooxanthellae in an aquarium, different as on the reef, due to the tendency of tanks to have larger amounts of dissolved nutrients. The zooxanthelle no longer rely on the coral for basic nutrients, rather absorb and assimilate straight from the water column.


    Red light is not more efficient at penetrating water. It is quickly attenuated (filtered) by increasing water depth. It is more efficient in photosynthesis than blue light, but this is a relationship recorded from land plants and does not consider attenuation via water. It can be misleading.



    Your conculsion is correct. Corals do best under a combination of blue and white. I wouldn't use the word actinic, as this refers to a small section of the blue-violet spectrum (420nm), although it is in common use. We are talking about light between 400nm-500nm in general, with the peaks you noted.

    I would add that, pigments respond to different wavelengths than zooxanthellae and may need parts of the spectrum outside of the classic PAR to complete pigment production. This can make it a bit more work to get the 'best' spectrum for any given group of corals.

    I hope you don't think I'm jumping on you.......

    Jamie
     
    K_ONE and Mc like this.
  5. scubaninja

    scubaninja Thread Starter

    Joined:
    20 Jul 2008
    Posts:
    6,739
    Likes Received:
    21
    Location:
    Durban
    Nah its all good, don't mind being corrected:thumbup: When I was first told of zooxanthelllae I was led to believe its actually them that protects the coral, so it's better to learn their actual purpose even if the general message of light on corals in correct :) So then, to just correct my above posts, the coral would change their pigment to reflect more light and not the zooanthellae?

    So what is the point of zooanthellae in the coral? If all the zooxanthellae were to die would that be detrimental to the corals health?
    Makes sense when you see tanks with great lighting and flow but the SPS are still brown.
    I was at odds in my mind about this face as well but thought as it was in the article I must be incorrect, reread that part in the article now and I have misinterpreted the information. Putting it down to late night reading:tt2: Do you have a link to any articles that go with your corrections? I'd like to read up on it more if possible;)
     
  6. butcherman

    butcherman Moderator MASA Contributor

    Joined:
    7 Sep 2009
    Posts:
    11,626
    Likes Received:
    280
    Location:
    Kempton Park
    yes more information please Jamie
     
  7. Jamie@Vertex

    Jamie@Vertex

    Joined:
    6 Aug 2011
    Posts:
    189
    Likes Received:
    17
    Location:
    Germany
    I can highly recommend all of Dana Riddle's articles. They are well considered, albeit sometimes not so straight foreward as on the first read through. The subject of lighting is complex. Not just due to the spectrum, but from the point of view you study it. As I was hinting, pigments and zooxanthellae are seperate entities. Zooxanthellae, as they are alga, are relatively easy to understand. They follow the basic scheme of photosynthesis, except that they have adapted themselves to various spectra, depending on the guild they belong to. Even with the knowledge we have gather on these symbionts, it is still difficult to decide what coral has what type. Many corals have a whole orchestra of different guilds, which seems to make them more flexible. The dominant guild is best adapted to the corals environment. As corals may fragment in nature, it is wise to have some zooxanthellae available that allow the frag to adjust to its new environment, which may be deeper or shallower as the mother colony.

    The zooxanthellae are responsible for up to 90% of a corals energy. Some corals are better able to assimilate plankton than others, and some corals have abandoned their zooxanthellae altogether (Tubastrea sps). Most of the corals we keep require proper lighting to maintain their zooxanthellae populations. These populations are partly dependant on available free nutrients, as well as the light for their photosynthesis. If a zoxanthellate coral looses all its symbionts at once, it will tyically die. It has no way of adjusting its metabolism to the new situation. However, if weaned off of its zooxanthellae, it can easily survive with an extremely small population. This weaning is an important concept, as we have all heard/seen tanks with bleached and suddenly dead corals due to over filtering or over lighting. Ultimately, corals are amazing adaptors, but they require time, plus need the genetic disposition to adapt. Not all corals are created equal.

    Pigments are a different story. They come in a wide variety of types and clades. Overly complex to discuss here, but, again, Dana Riddle has distilled some of the general concepts into his articles. Pigments are protiens, which means they are 'expensive' for the coral to produce, therefore corals only produce them if they are required. Reasons for pigment development vary and, to date, it is a wildly discussed area of coral metabolism. We do know certain parts of the spectrum favour certain pigments production. Also, fluorescent pigments require specific wavelengths to give of their light. Still, when compared to the light required for general health, the spectra involved in pigment production plays a small role. On a reef, most corals are brown, rather than heavily pigmented. Also, due to the general mix of light on a reef, the fluorescent quality is literally unnoticable. This is something we have learned to manipulate, not a quality of their natural state. Aquariums have allowed for this aesthetic development.

    Jamie
     
    K_ONE likes this.
  8. scubaninja

    scubaninja Thread Starter

    Joined:
    20 Jul 2008
    Posts:
    6,739
    Likes Received:
    21
    Location:
    Durban
    Thanks for that info Jamie :thumbup: Much appreciated. Clears some stuff up nicely :) Will have a look through Dana Riddle's articles when time permits the lengthy study of the articles in order to understand :p
     
Recent Posts

Loading...
Similar Threads - Effects Narrow Bandwidth Forum Date
What light colour effects algae?? General Discussions and Advice 2 Jun 2015
Side effects of cheap supplements General Discussions and Advice 26 Nov 2013
negative effects of magnesium being too high? General Discussions and Advice 18 Oct 2011
Side Effects of High CA , ALK and MG Water Parameters and Additives 10 Oct 2011
live rock - effects General Discussions and Advice 21 May 2009
Kessil Lighting In. A350 (narrow-angle) and A150 Deep Ocean Blue (Actinic) now... Aquarium Depot 7 Nov 2012