what gives sps their colour?
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Dugless
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SPS coral can be found in just about every imaginable color. The color seen within coral tissue comes from the marine algae, zooxanthellae, which reside within the polyp tissues. Zooxanthellae have a range of pigments, including fluorescing pigments.
The color changes seen over time in a coral are reflective of the amount and type of zooxanthellae within a coral. The tips and edges of fast growing corals are usually pale, as they have not yet become saturated with zooxanthellae. Similarly, corals that are pale in their entirety have a very low population of zooxanthellae throughout. A brown coral is typically over saturated with zooxanthellae, usually a result of higher nutrient levels. This variability of zooxanthellae is most readily recognizable in Acropora.
The color changes seen over time in a coral are reflective of the amount and type of zooxanthellae within a coral. The tips and edges of fast growing corals are usually pale, as they have not yet become saturated with zooxanthellae. Similarly, corals that are pale in their entirety have a very low population of zooxanthellae throughout. A brown coral is typically over saturated with zooxanthellae, usually a result of higher nutrient levels. This variability of zooxanthellae is most readily recognizable in Acropora.
Thanks for the detailed reply!
Would it be correct to assume that all acropora in a tank will end up with the same colouration after some time even if they were of different colours to begin with?
Would it be correct to state also that high nutrient levels result in a production of larger amounts of inorganic molecules by the coral to the zooxanthellae, thus fuelling their exponential growth via photosynthesis?
My last question would be if a browned out sps is actually healthier than a fully coloured one
Would it be correct to assume that all acropora in a tank will end up with the same colouration after some time even if they were of different colours to begin with?
Would it be correct to state also that high nutrient levels result in a production of larger amounts of inorganic molecules by the coral to the zooxanthellae, thus fuelling their exponential growth via photosynthesis?
My last question would be if a browned out sps is actually healthier than a fully coloured one
Dugless
New member
Each acropora hosts zooxanthellae with pigmentation unique to that coral. The coral color is dependent upon what zoox is already available within the coral. While the population of these different algaes can vary and shift the color, it has been my understanding that 'new' variants of this zoox cannot be obtained. So it is possible to get shifts in color, but not entire changes. Blue to purple, Green to yellow, Red to pink, things like that. Definitely not red to green.
The color of lighting also helps in how we perceive the color as well.
There are so many variables that affect growth that it is tough to speculate if coral with higher zoox population are any more productive in this area.
Some have the opinion that brown acros are more resilient to changes, but again this could be speculative.
The color of lighting also helps in how we perceive the color as well.
There are so many variables that affect growth that it is tough to speculate if coral with higher zoox population are any more productive in this area.
Some have the opinion that brown acros are more resilient to changes, but again this could be speculative.
Dugless
New member
Acropora, in general, are some of the most tolerant corals available. The labelled difficulty has more to do with creating a stable environment in which they can thrive and are colorful. Acros can remain healthy in saturated and deficient NO3 and PO4 waters, but if these nutrients fluctuate often, you can expect the corals to suffer. The key to success with SPS, is to keep your parameters within range and absolutely stable. Most importantly, Alk, Ca, Mg, Salinity, NO3 and PO4.
plantastic
New member
The Zooxanthellae is responsible for the brown, goldish, tan base color to the coral. A lot of the other colors are a result of FP's (Fluorescing Proteins) and MAA's (Mycosporine-like Amino Acids) , which are both produced by the coral itself.
Pife
Active member
Do you have any good articles on this? I would like to read more about it.
plantastic
New member
I do, but they are not pdf's. They are copies of peer reviewed, published papers. I sourcd them from scouring the bibliographies of intermediate/ advanced books of the hobby.
One of the best studies recently published is this one.
http://onlinelibrary.wiley.com/doi/10.1111/mec.13041/abstract
This work describes how the color morphs in Acropora millepora are related to the copy number variants of the genes encoding certain fluorescent proteins (FPs, present in the coral not in the zooxanthellae), which have a role in protecting the coral against excessive sunlight, as happens in shallow waters.
One of the interesting results is that some morphs produce more FPs in the shadow than others under bright light. Therefore the old struggle to get the best water parameters, best nutrition and best light will not produce the best colors if the morphs we have are not the best in genetic terms.
http://onlinelibrary.wiley.com/doi/10.1111/mec.13041/abstract
This work describes how the color morphs in Acropora millepora are related to the copy number variants of the genes encoding certain fluorescent proteins (FPs, present in the coral not in the zooxanthellae), which have a role in protecting the coral against excessive sunlight, as happens in shallow waters.
One of the interesting results is that some morphs produce more FPs in the shadow than others under bright light. Therefore the old struggle to get the best water parameters, best nutrition and best light will not produce the best colors if the morphs we have are not the best in genetic terms.
MAAs are colorless, so they can hardly contribute to the coral color
plantastic
New member
Chema- Your right...I was remembering incorrectly! It has been quite a few years since I've read these articles. My apologies for MIS-information!
Looks like it is a mixture of Chroma proteins, Fluorescing Proteins, and Heat shock Proteins that are responsible. As well as a genetic predisposition.
Looks like it is a mixture of Chroma proteins, Fluorescing Proteins, and Heat shock Proteins that are responsible. As well as a genetic predisposition.
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Not Quite. The only colour that zooxanthellae contribute is a golden brown.
The proteins responsible for colour in corals are expressed directly by the coral.
mhucasey
Acros & wieners, oh my!
Coral fluorescing pigments are a way for the coral to do a couple of things with the light that they receive:
1) The pigments may prevent oxidation from the high rates of photosynthesis in the coral tissue.
2) The pigments convert one wavelength of light into another, diverting excess photosynthetic light away from photosynthesis when too much light is present.
3) When too little light is present or when limited wavelengths of light are present, some pigments convert non photosynthetic wavelengths into wavelengths that can be utilized for photosynthesis.
Zooxanthellae are tan and do not contribute any other color.
1) The pigments may prevent oxidation from the high rates of photosynthesis in the coral tissue.
2) The pigments convert one wavelength of light into another, diverting excess photosynthetic light away from photosynthesis when too much light is present.
3) When too little light is present or when limited wavelengths of light are present, some pigments convert non photosynthetic wavelengths into wavelengths that can be utilized for photosynthesis.
Zooxanthellae are tan and do not contribute any other color.
Dugless
New member
Ok, so let me get this straight. These fluorescing pigments move to the surface of coral tissue in high light situations to help screen/reflect intense irradiance from damaging zooxanthellae. However in low light conditions, these same pigments settle within and below the zooxanthellae to amplify energy production by converting and reflecting light back to the symbiotic algae.
Is it too simplified to assume that limiting zooxanthellae with low nutrients in a higher light environment would result in a more colorful coral because these pigments would have a less saturated backdrop of brown zooxanthellae to compete with?
Is it too simplified to assume that limiting zooxanthellae with low nutrients in a higher light environment would result in a more colorful coral because these pigments would have a less saturated backdrop of brown zooxanthellae to compete with?
Nano sapiens
New member
This is the rationale for the 'ULNS' (Ultra Low Nutrient System). Some methods even go so far as cause the coral to expel some of it's normal compliment of zooxanthellae.
mhucasey
Acros & wieners, oh my!
There are different pigments for different light conditions. When they mariculture SPS for example, the corals are grown in shallow water to maximize the total light on the coral, and more zooxanthellae are supported. The coral grows more rapidly but the colors are a combination of the pigments needed to deal with high light and the zooxanthellae brown. Before shipping to market, the corals are moved to deep water where blue, violet, and green light are the only wavelengths that penetrate. The coral produces different pigments here mostly to repurpose the light to get the most benefit from these wavelengths. Zooxanthellae density also drops because there isn't as much light to support them. The colors produced in this environment are what we think of as the prettier colors of acropora.
In the reef tank, it is a balance of providing a low nutrient environment to limit zooxanthellae proliferation, providing lots of blue light to stimulate the pretty colors and grow the coral, and just enough red and yellow to see the colors accurately. In the older days people used Iwasaki 6500K metal halides in an attempt to mimic the shallow water conditions - corals grew well but the colors were not so good, tending toward brown.
So to answer the question, yes, the best coloration comes from high amounts of the right spectrum of light, combined with low nutrients. The corals also need energy and food to produce the pigments so there is a nutritional component that plays into the mix as well.
