Understanding the color of corals

Discussion in 'General Discussions and Advice' started by Jaco Schoeman, 28 Jan 2010.

  1. Jaco Schoeman

    Jaco Schoeman MASA Contributor

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    Hi guys, I have done this short quote from an article I have (on another thread too) but I thought to just make a new thread on it, so all nuubs can also understand the science behind coral color a bit better:

    I have more info for those who wants it: ;)

    Article by Don S. Johson

    Quote 1:


    "The name zooxanthellae means "little yellow creatures" in Greek because this was the color of the first symbiotic algae found (although it was first thought to be a parasite.) Brown and yellow are best suited to absorb the blue wavelengths of light, which penetrate deepest into water."

    This makes sense, as to why the deeper corals (NPS excluded) are then brown...

    Quote 2:

    "Coral polyps are naturally white or transparent, with color imparted by zooxanthellae. Color and intensity are determined by both the strain of zooxanthellae and the number of them in each polyp - determined by the polyp's needs and a result of environmental conditions such as light, temperature and water conditions...

    Zooxanthellae themselves are varying shades of green, brown, tan or gray, depending on the light they receive and also the color of the skin of the animal they inhabit. Shallow-water animals are usually green because they tend to receive the full spectrum and intensity of sunlight...

    Polyps may be yellow, orange, purple or blue, for example. These animals do not require photosynthetically active radiation (PAR), and too bright a light (metal halids, for example) may even be harmful without a period of gradual acclimatization. The yellow and orange comes from carotenoids obtained from food. Examples include Tubastrea sp. (Sun Corals)

    The equisite blue color of Semperina sp. polyps likely comes from concentrations of blue carotenoprotein in this Indo-Pacific gorgonian. Such melanin, which makes things black, are known as biochromes.

    Previosly, I explained that greem zooxanthellae indicate animals from shallower water. This is true, but how green is green. Anchor Coral is tan on the reef flats, pale green on reef slopes and dark green on the upper reef.

    Gorgonians are colored by carotenoids stored in the calcareous spincules scattered in the flesh surrounding the horny skeleton.

    Soft Coral polyps with zooxanthellae tend to be some shade of brown - shallow water specimens may be some shade of gray. Soft Coral polyps that are colored otherwise contain no zooxanthellae.

    Xenia sp. a soft coral, has lost the ability to eat and depends on zooxanthellae for nourishment (Lange, 1997) and is usually some light shade of grey." - END QUOTE

    :biggrin:
     
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  3. jacquesb

    jacquesb Retired Moderator

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    Tagging along to see what the "experienced reefers" (who have investigated this) says! ;)
     
  4. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Thanks Jacques, I agree, more insight might be helpful.

    If I may, I would however like to paste your comment from the other thread here too, as this must not be miunderstood, and your comment is spot on!!!

     
  5. dallasg

    dallasg Moderator MASA Contributor

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    yes i have a frogspawn that is completely white, it lost its color while i was experimenting with LED's etc, this coral is almost transparant, i am now slowly giving it correct lighting and the color is returning slowly, zoozanthallae can also migrate from speecies to species and i am waiting to see if the colour it gets is different from its mother colony
     
  6. jacquesb

    jacquesb Retired Moderator

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    I have also previously read that zooxantellae can be taken up from the water, as well as from food (which contain zooxantellae).....
     
  7. dallasg

    dallasg Moderator MASA Contributor

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    a zoozanthallae migration, but lets see what the coral experts say
     
  8. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Yes, this article I have explains it nicely, again, may I quote:

    " A dinoflagellate is a single-celled creature that swims by lashing threadlike tails - one extending backward, one in the girdle, hence the name dinoflagellate from two flaggelae. They swim by rotating these like a helicopter's rotor. (The girdle refers to the thin center section of the animal that divides the cell into "head" and "tail" ends, though it properly has no head.)

    We're not really sure how, but the polyp "eats" the dinoflagellate, and instead of digesting it, builds a cellular "cage" from a special membrane around it. Once inside the polyp, the dinoflagellate loses it flagellae (propellars) and becomes a zooxanthella. The polyp can move the zooxanthella around to the best position for photosynthesis and the best position to extract nutrients from it."

    END QUOTE...

    Interesting huh?

    And here is how a dinoflagellate looks like:

    [​IMG]
     
  9. dallasg

    dallasg Moderator MASA Contributor

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    a great day for learning :)
     
  10. jacquesb

    jacquesb Retired Moderator

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    I still think that zooxantellae does not supply the bright coloration of SPS corals.... Let met do some trawling on Google....
     
  11. Neil H

    Neil H Moderator MASA Contributor

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    cant remember where this comes from but here is something i found
    "Zooanthellae
    migration
    Another issue that can effect the visual appearance of corals is a mechanism that allows them to take in new zooanthellae from the water stream. This is a complex survival mechanism that is not fully understood but it is presumed to allow corals to survive in changing environments. The coral can select a more suitable algae cell from the water; this better provides energy in a particular environment. This is sort of a fit for purpose mechanism. The effect can often lead to corals changing colour hence you find the effect where corals over time, in a particular aquarium with a given set of water parameters,
    can mostly migrate to a specific colour caused by the selection of more favourable cell."
     
  12. jacquesb

    jacquesb Retired Moderator

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    Here you go. A VERY interesting read:
    http://www.reefs.org/library/talklog/d_riddle_042698.html

    Particularly this part: (and I quote)
    "
    Alkalinity

    We offered this information and were a bit surprised at the debate these comments generated. This is the background - we have 10 - 1,500 gallon systems in our facility; four of these house stony corals. e allowed the alkalinity to drop in these systems to that of natural seawater (~ 7 dKH). We noted that many of these corals' colors faded during this period.
    Two commercially available buffers (Inland Seas and Warner Marine Research) were used to quickly raise alkalinity levels to 10 dKH. In some cases, the pigmentation intensified overnight. Other colors returned over a period of days. No other system parameters were altered. This procedure was performed in two other systems with the same results.
    We are not sure why the colors return - is the increased bicarbonate a catalyst for increased photosynthesis? Or is the alkalinity shift a stressor to the corals and they lose (or alter) their zooxanthellae and the pigments (which are below the zooxanthellae "layer") become apparent. Testing is underway to determine the effect of alkalinity on zooxanthellae density/size and, with any luck, photodocumentation will be presented at the September MACNA X in Los Angeles, California."
     
  13. jacquesb

    jacquesb Retired Moderator

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    Something else I found too:
    URL: Heavy Metal Trace Elements and Potential Effects on Zooxanthellae and Coral Color from Toxicity | glassbox-design.com
    Quoted:
    "
    Why would aquarists care about expelling zooxanthellae? That is a damning question. For aesthetics, less zooxanthellae algae within the tissue of Acroporids results in increased coloration. The dreaded “brown” is generally caused by the corals symbiotic zooxanthellae algae. If this is removed the pigments underneath can show better… or in some cases the lightened palette provides a better contrast. Purple on white or purple on brown?
    At one point a test was done on a specific proprietary liquid supplement that caused coral tissue to lighten in order to enhance coloration. Supposedly it was found to contain copper. Some where surprised by this, and scared because of the toxicity we associate with the word. Copper is known to be lethal to inverts and doubles as a treatment for Cryptocaryon, aka Ick. However, copper is a natural trace element found in the ocean, and correspondingly so in synthetic salt mixes. Little do most aquarists know, many of the “inputs” that we add to our tank, such as fish food, can contain copper. Copper and other metals are also incorporated into protective anti-oxidative enzymes within coral tissues."
     
  14. jacquesb

    jacquesb Retired Moderator

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    OK - I think that I have found the "holy grail" of coral coloration - here are quite a few URLs to read through, for some bed-time reading ;)

    http://www.advancedaquarist.com/2007/2/aafeature

    Advanced Aquarist's Online Magazine - Feature Article: How to Make Corals Colorful, Part One: New Information, With Particular Attention to Blue-Green Fluorescent Pigments

    Advanced Aquarist's Online Magazine - Feature Article: How to Make Corals More Colorful Part 3 - New Information: Red Fluorescent Pigments: DsRed-type

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration, Part Five: Non-fluorescent Chromoproteins (CP-480 to CP-562)

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration, Part 6: Non-fluorescent Chromoproteins (CP-568 – CP-610) And A Newly Discovered Colorant

    Advanced Aquarist's Online Magazine - Feature Article: How to Make Corals More Colorful, Part Two: New Information! Green Fluorescent Pigments, Pigment Clades, and Photoconversion from Green to Orange/Red

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration, Part 3: Pigments Responsible for Yellow and Orange Coloration, With Notes on Photoconversion

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration, Part 2: Fluorescence: Pigments 510 - 565 and Notes on Green Fluorescent Proteins

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration, Part 8: Blue and Green Coral Fluorescence: Environmental Factors Affecting Fluorescent Pigmentation

    Advanced Aquarist's Online Magazine - Feature Article: Coral Coloration: Fluorescence: Part 1
     
  15. Adee

    Adee

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    Exactly what I was led to believe should be the aim of reefers trying to get the best color out of sps's. Is that not why we aim to go to ULNS systems?

    Secondly, the "sunburn effect"....you must have the right PAR and intensity spectrum, hence why corals positioned high to the water edge show more coloration than the same specie sistuated lowerdown.

    get these two right in your system and you got color all the way down the stems with the guys placed below showing improved coloration

    As a "layman", (ain't no scientist)...would I be right with this basic aproach?
     
  16. jacquesb

    jacquesb Retired Moderator

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    I find this particularly interesting:
    Quoted:
    "
    Types of Pigments

    There are at least 9 described types of coral pigments. Note: Pigment types, such as green or red might not be structurally similar to another green or red pigment in a different clade - see below). These include:

    • Cyan Fluorescent Proteins (CFP) - Cyan pigments are blue-green pigments with a maximum emission of up to ~500 nm. The chromophore structure of a cyan pigment is very similar to that of a green fluorescent pigment.
    • Green Fluorescent Proteins (GFP) - This group, by far, is the most numerous of the fluorescent proteins. The structure of green fluorescent chromophores is very similar to that of cyan fluorescent chromophores.
    • Yellow Fluorescent Proteins (YFP) - An unusual type of fluorescent protein with maximum emission in the yellow portion of the spectrum. Rare in its biological distribution, YFP is found in a zoanthid and some specimens of the stony coral Agaricia. Personally, I've noted yellow fluorescence in a very few stony corals (Porites specimens) here in Hawaii while on night dives using specialized equipment to observe such colorations (see NightSea Home for details on this equipment).
    • Orange Fluorescent Protein (OFP) - I've included this protein 'type' in an attempt to avoid confusion. OFP is used to describe a pigment found in stony coral Lobophyllia hemprichii and its name suggests a rather unique sort of protein. In fact, OFP is simply a variant of the Kaede-type fluorescent proteins.
    • Red Fluorescent Proteins (RFP) - A group of proteins including several different subtypes (Kaede, Ds-Red and Chromo-Red). Typically, fluorescent emission is in the range of ~580 nm to slightly over 600 nm.
    • Dronpa - A green fluorescent protein that loses fluorescent when exposed to blue-green light (~490 nm) but returns when irradiated with violet light at ~400 nm.
    • Kindling Proteins - A protein (notably from the anemone Anemonia sculata) that changes from a non-fluorescent pigment to one demonstrating fluorescence. This change is switchable/reversible and its state depends upon the spectral quality of light striking it.
    • Chromo-Red Proteins - A new classification (Alieva et al., 2008) of a single fluorescent pigment found in the stony coral Echinophyllia. This chromo-red pigment has qualities of a non-fluorescent chromoprotein, but fluoresces at a maximum of 609 nm.
    • Chromoproteins (CP) - This group of pigments is non-fluorescent, or has minimal fluorescence (where the quantum yield is essentially zero). Instead of relying upon fluorescence for coloration, these pigments instead absorb light most strongly in a relatively narrow portion of the visible spectrum. Most coral chromoproteins absorb light maximally at 560-593 nm. There are reports of anemones absorbing light at a maximum wavelength of 610nm, and a couple of reports of stony corals absorbing wavelengths in the 480-500nm range. Some chromoproteins are very similar in structure to the fluorescent Ds-Red proteins. In fact, genetic engineers have found that a single amino acid substitution in a protein can make the difference between non-fluorescence and fluorescence. Chromoproteins do not get much attention by researchers (relative to that of fluorescence proteins) and there are only about 40 described."
     
  17. jacquesb

    jacquesb Retired Moderator

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    Adee - It seems that alkalinity levels has a huge effect on the coloration of SPS corals - an alkalinity level of around 10 is suggested to bring the coloration of SPS out even more.

    Also - higher nutrient levels is not specifically the cause for coral-browning, as per popular believe.

    Neither does higher lighting cause zooxanthellae to be reduced within coral tissue.... (read through the articles I posted - it's all there)....

    Another interesting quote:
    "The experimental results of D'Angelo et al. offer fascinating insights on the effects of light intensity and spectral qualities on coral pigmentation. Some pigments require relatively little light while others are not expressed until light intensity reached a certain threshold. At least one pigment examined decreased in concentration upon exposure to increasing light intensity. By the same token, production of coral pigments by the coral animal can be a response to different colors of light and each pigment class seems to have a different reaction to 'colored' light."
     
  18. jacquesb

    jacquesb Retired Moderator

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    Another quote:
    "
    Types of Pigments

    There are at least 9 described types of coral pigments. Note: Pigment types, such as green or red might not be structurally similar to another green or red pigment in a different clade - see below). These include:

    1. Cyan Fluorescent Proteins (CFP) - Cyan pigments are blue-green pigments with a maximum emission of up to ~500 nm. The chromophore structure of a cyan pigment is very similar to that of a green fluorescent pigment.
    2. Green Fluorescent Proteins (GFP) - This group, by far, is the most numerous of the fluorescent proteins. The structure of green fluorescent chromophores is very similar to that of cyan fluorescent chromophores.
    3. Yellow Fluorescent Proteins (YFP) - An unusual type of fluorescent protein with maximum emission in the yellow portion of the spectrum. Rare in its biological distribution, YFP is found in a zoanthid and some specimens of the stony coral Agaricia. Personally, I've noted yellow fluorescence in a very few stony corals (Porites specimens) here in Hawaii while on night dives using specialized equipment to observe such colorations (see www.nightsea.com for details on this equipment).
    4. Orange Fluorescent Protein (OFP) - I've included this protein 'type' in an attempt to avoid confusion. OFP is used to describe a pigment found in stony coral Lobophyllia hemprichii and its name suggests a rather unique sort of protein. In fact, OFP is simply a variant of the Kaede-type fluorescent proteins.
    5. Red Fluorescent Proteins (RFP) - A group of proteins including several different subtypes (Kaede, Ds-Red and Chromo-Red). Typically, fluorescent emission is in the range of ~580 nm to slightly over 600 nm.
    6. Dronpa - A green fluorescent protein that loses fluorescent when exposed to blue-green light (~490 nm) but returns when irradiated with violet light at ~400 nm.
    7. Kindling Proteins - A protein (notably from the anemone Anemonia sculata) that changes from a non-fluorescent pigment to one demonstrating fluorescence. This change is switchable/reversible and its state depends upon the spectral quality of light striking it.
    8. Chromo-Red Proteins - A new classification (Alieva et al., 2008) of a single fluorescent pigment found in the stony coral Echinophyllia. This chromo-red pigment has qualities of a non-fluorescent chromoprotein, but fluoresces at a maximum of 609 nm.
    9. Chromoproteins (CP) - This group of pigments is non-fluorescent, or has minimal fluorescence (where the quantum yield is essentially zero). Instead of relying upon fluorescence for coloration, these pigments instead absorb light most strongly in a relatively narrow portion of the visible spectrum. Most coral chromoproteins absorb light maximally at 560-593 nm. There are reports of anemones absorbing light at a maximum wavelength of 610nm, and a couple of reports of stony corals absorbing wavelengths in the 480-500nm range. Some chromoproteins are very similar in structure to the fluorescent Ds-Red proteins. In fact, genetic engineers have found that a single amino acid substitution in a protein can make the difference between non-fluorescence and fluorescence. Chromoproteins do not get much attention by researchers (relative to that of fluorescence proteins) and there are only about 40 described."
     
  19. jacquesb

    jacquesb Retired Moderator

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    My summary:

    So - basically, coral colors are due to one of the following:
    1) colored pigment
    2) colored proteins

    Bringing these colors out, could possibly involve the following:
    - dosing some types of additives that contain metals/minerals
    - increasing the alkalinity to ie. 10
    - possibly increasing lighting (for SOME corals)
    - decreasing lighting (for some corals)
    - dosing iodine (to improve fluorescence)
    - perhaps a very wide variety coloration globes, to bring out the coloration, as well as fluorescence from the 400nm to 600nm range....

    This is my opinion only - but, please feel free to add to this....

    I know - I know. You all use the ULNS system to bring the coloration out of your SPS corals. And this does seem to work.....

    BUT, nowhere in these articles did I find any other reference/proof of this? If I misread, please enlighten me?
     
  20. Adee

    Adee

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    mmmhhh, I'm gonna have to examine this more over the weekend...I may other views on Monday :p.

    I dunno, but the tanks that make the totm on the Zeovit site really rock like no others when it come to sps coloration. A lot points to lighting choice and required dosing regime that create the LN environment. ULNS systems seem like the "proven" route.

    IF these articles and practises say otherwise....would be interesting to see FTS pics of systems able to match/better what already once could say is an acknolwedge route in gaining sps coloration.
     
  21. Neil H

    Neil H Moderator MASA Contributor

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    1000 0000% agree those DTOTQ etc are stunning amazing if i achieve that then i can start tweaaking other parameters ......

    I have noted that many of the DTOTQ use the majority of lighting in T5 format and not MH, some even going as far as saying MH do more harm than good in these systems .... ?????? .... also note the difference in flow regimes some have surprisingly little flow for the SPS they keep, everything points back to the comonality of the rapid nutrient cycling system.,...... i HATE the LNS or ULNS terms as they are completely misleading !!!
     
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