Distorted/mutant morphology in Acroporas radial and axial corallite structure.

[C. Eymann]

Something I have noticing for a while now is the very unique/strange morphology in certain species of acropora when grown under LED only lighting, compared with corals grown under t5/led hybrid, MH and T5 only.
Example- I notice with led only grown A. tenuis that the dimidiate (lip)of the radial corallites is usually "distorted" or irregular instead of being uniform.
The axial corallites of some species almost appear to be melting/distorted like a candle stick.
Where as the same species grown under T5 hybrid or T5 only /MH doesn't show these "distortions".

Has anyone else noticed this?

 

[Gareth elliott]

I have not seen this, but if is true; could be promising for wild colonies. If able to make quite rapid morphological changes to captive lighting; might hold true for climatological changes, like how porites controls its inner pH.

Side note might be beneficial for the discussion for members that say yes or no to post a picture of said observation, along with lighting setup and species ID.

 

[C. Eymann]

I guess I should post a pic or two for my example

Top coral is a A. tenuis that has been maricultured (propagated and grown out in the ocean under natural sunlight)

Notice how the radial corallites rims' are smooth an fairly uniform.

Here is a tenuis grown under LEDs that a user posted just recently.
Notice the irregular/ rough distorted structure of the radial corallites.

 

[flockaveli]

I would agree 100%. I have noticed this too many times to think nothing of it. My LFS was the first place I saw Acropora getting strange growth from LED only system.

Maybe it has to do with the spectrum as well? or intensity? Seems to really affect corallite structure the most. Even makes the tissue look a little warty in areas.

The bottom pic of the A. Tenuis is a perfect example of what I have seen.

 

[AllSignsPointToFish]

This is probably going to sound stupid, but I'm just fishing in the dark here. Do you think the resulting distortions could be due to constructive/destructive interference in the light produced by the LEDs in the fixture. While admittedly unlikely, the LED fixtures are composed of an array of LEDs radiating at separate, distinct wavelengths. Metal halide and fluorescent are more of a continuous spectrum than an array of point sources of fixed wavelength. In addition, the way the light envelope is distributed via metal halide or fluorescent should be more mixed, possibly reducing gaps in the overall spectrum.

Of course, it could also just be that LED fixtures are deficient in certain wavelengths that other light sources and mother nature provide.

Like I said....just fishing in the dark here.

 

[C. Eymann]

I would agree 100%. I have noticed this too many times to think nothing of it. My LFS was the first place I saw Acropora getting strange growth from LED only system.

Maybe it has to do with the spectrum as well? or intensity? Seems to really affect corallite structure the most. Even makes the tissue look a little warty in areas.

The bottom pic of the A. Tenuis is a perfect example of what I have seen.

This is probably going to sound stupid, but I'm just fishing in the dark here. Do you think the resulting distortions could be due to constructive/destructive interference in the light produced by the LEDs in the fixture. While admittedly unlikely, the LED fixtures are composed of an array of LEDs radiating at separate, distinct wavelengths. Metal halide and fluorescent are more of a continuous spectrum than an array of point sources of fixed wavelength. In addition, the way the light envelope is distributed via metal halide or fluorescent should be more mixed, possibly reducing gaps in the overall spectrum.

Of course, it could also just be that LED fixtures are deficient in certain wavelengths that other light sources and mother nature provide.

Like I said....just fishing in the dark here.

Excellent questions and hypotheses.

I have been wondering for a while now why this occurs and havent really found any data on it and remain clueless as to why ?

Maybe @Dana Riddle might have some thoughts and expertise on this anomaly ?

 

[Mical]

Interesting & following

 

[Timfish]

Yup, here's a link, look at fig. 1

Contrasting Light Spectra Constrain the Macro and Microstructures of Scleractinian Corals

The morphological plasticity of scleractinian corals can be influenced by numerous factors in their natural environment. However, it is difficult to identify in situ the relative influence of a single biotic or abiotic factor, due to potential interactions between them. Light is considered as a...

journals.plos.org

 

[SeaDweller]

I guess I should post a pic or two for my example

Top coral is a A. tenuis that has been maricultured (propagated and grown out in the ocean under natural sunlight)

Notice how the radial corallites rims' are smooth an fairly uniform.

Here is a tenuis grown under LEDs that a user posted just recently.
Notice the irregular/ rough distorted structure of the radial corallites.

When I saw that pic in the other thread I didn’t know if it’s just bad lighting, photo skills or distortion from the water, but can we attribute it to the lighting only? I certainly don’t see THAT in any of mine.

 

[Dana Riddle]

I've never observed corallite deformation as shown in the photos above but find it interesting as to possible cause(s).
A couple of comments about the paper Tim posted. The PAR meter used (Apogee MQ-200) is not recommended for use with LEDs. No mention of water velocities, other the tanks' setup was identical - a water velocity meter should have been used. I've got a $5,000 Marsh-McBirney electronic water velocity meter and can state that we shouldn't assume this parameter is the same in each tank. There is an interesting tidbit in that article - a separate research paper suggests corals grew faster under LEDs. Perhaps a fast-growing coral exposed to wavelengths thought to promote growth causes these irregularities.

 

[AllSignsPointToFish]

I've never observed corallite deformation as shown in the photos above but find it interesting as to possible cause(s).
A couple of comments about the paper Tim posted. The PAR meter used (Apogee MQ-200) is not recommended for use with LEDs. No mention of water velocities, other the tanks' setup was identical - a water velocity meter should have been used. I've got a $5,000 Marsh-McBirney electronic water velocity meter and can state that we shouldn't assume this parameter is the same in each tank. There is an interesting tidbit in that article - a separate research paper suggests corals grew faster under LEDs. Perhaps a fast-growing coral exposed to wavelengths thought to promote growth causes these irregularities.

Very interesting thoughts!

 

[Dana Riddle]

I guess I should post a pic or two for my example

Top coral is a A. tenuis that has been maricultured (propagated and grown out in the ocean under natural sunlight)

Notice how the radial corallites rims' are smooth an fairly uniform.

Here is a tenuis grown under LEDs that a user posted just recently.
Notice the irregular/ rough distorted structure of the radial corallites.

Do you have any PAR numbers by chance?

 

[madweazl]

I'd suspect water movement over light if we're comparing maricultured vs in tank.

 

[blasterman]

>>>>>>>>Metal halide and fluorescent are more of a continuous spectrum than an array of point sources of fixed wavelength

No, they are not, and this kind of disinformation really needs to cease.

Seriously....use google and look up the spectrums of reef based halides. I'll do it for you:

Underwater Light Field and its Comparison to Metal Halide Lighting

This article presents some data on the underwater light field on a reef and compares it to the artificial light field over our reef aquaria, along with discussion of other features of natural lighting that are often not simulated in our aquariums.

www.advancedaquarist.com

Now go look up the published spectrums of any mainstream reef LED. Now show me again where the halide or T5 has a more continuous spectrum -vs- repeating what the guy at the reef store. The graphs are there......they can't be more obvious if they were in crayon. Seriously, show me a link to a halide or T5 with a continuous spectrum.

Metal halide and fluorescent like fixtures have NON-continuous spectrums while LED's have much more continuous spectrums . This is one reason why the mainstream lighting industry is banning and ditching conventional fluorescent and halide in favor of LED.

The reason SPS can grow weird under some LED sources is because you guys want small, hyper dense LED fixtures with the emphasis on software and wi-fi and other worthless features -vs- distributing the light more evenly. If you want to blast a Radion or Kessil on a long or wide tank with a radiating area measured in a mere few square inches then SPS will grow unevenly. If you distribute the light source more evenly, like using a bunch of black boxes or strips like most of my SPS friends on big tanks there is no issue.

 

[naoki]

Yup, here's a link, look at fig. 1

Contrasting Light Spectra Constrain the Macro and Microstructures of Scleractinian Corals

The morphological plasticity of scleractinian corals can be influenced by numerous factors in their natural environment. However, it is difficult to identify in situ the relative influence of a single biotic or abiotic factor, due to potential interactions between them. Light is considered as a...

journals.plos.org

Pretty cool study, thanks for the share. It would be interesting if they can connect the response to adaptive significance in the future. Plants use phytochromes, cryptochromes, and phototropins to sense the light spectra, and modify their morphology. E.g. under shade, they grow more horizontally, leaves become thinner and more surface area (so-called shade leaves) etc. Corals are sessile, too, so they do need similar mechanisms to acliamate to the light environment.

Corals may be using blue light (relative to other wavelengths) as the indicator of depth. C.Eymann's photos aren't under the controlled environment, but the photo under LED reminds me of the shade leaves (each coralites larger, and spreading further from the stem, and more sparse arrangement). On the other hand, deeper depth should be correlated with less directional light, and I'm not sure what shape would be optimal for the diffused light.

 

[Dana Riddle]

I didn't have an issue with what @AllSignsPointToFish said about 'continuous spectrum' - I understand what he meant.
@blasterman said: If you want to blast a Radion or Kessil on a long or wide tank with a radiating area measured in a mere few square inches then SPS will grow unevenly.
Why don't we see this in all Radion/Kessil illuminated SPS aquaria?

 

[Ridgeway]

I would of thought growth form was more a result of flow than anything else, after all the flow in our aquariums is nothings vs what's out there on the reef. Even if we have 5-10 different flow patterns over a 24 hour period it's nothing compared with the constantly random flow found in nature.

 

[AllSignsPointToFish]

Okay, dude. Rant and rave all you want in a condescending fashion.

I would love to see how one gets a continuous spectrum from an array of LEDs radiating at fixed wavelengths and a single operating point (like most do in aquaria) without a transfer function to fill in the gaps in the spectral frequencies. My guess would be the published LED spectra are smoothed to make them appear continuous (and full disclosure: I run six Kessil LEDs on my tank). Either that, or the manufacturers average the spectra over the entire range of possible operating points (color channels, intensity, etc.) to produce the published figure. Just a guess as I'm sure that exact information is proprietary for each manufacturer. Even though I'm a Kessil user, I highly doubt that modifying the light output from a bluer tint to a whiter tint has no impact on output spectra.

With metal halide and especially the phosphors in fluorescent lamps, the UV emissions of the electric arc are converted to different wavelengths. There are variations in these spectra by design as the lamps are intended to emphasize certain beneficial frequencies, but the manufacturers control the spectra with specific mixes of metal halides or phosphors to modify the output spectrum.

However, like I said before, it was only a guess, and I'm willing to admit the hypothesis could be wrong. Looking at the spectra in the cited paper, maybe it's possible the issue is not that there are gaps in the lighting spectrum, but rather maybe there are differences in which emissions wavelengths are emphasized in each lighting type that leads to differences in skeletal growth. Maybe the PAR for one type of lighting is spread too evenly over the 340-840nm bandwidth instead of emphasizing the right frequencies relating to growth. That hypothesis would be consistent with the cited paper and could explain the observed differences in skeletal growth.

Then, of course, it could always just be a matter of flow.

 

[TexasReefer82]

I have a hard time believing that light spectra from LED's are any more continuous that those from MH's or T5's. From wikipedia:

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.[5] White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.[6]

The band gap is an energetic transition of fixed and uniform magnitude (depending upon the materials used of course). While there is a small amount of spread in the wavelengths emitted from this band gap it's mostly monochromatic. And in the case of white LED's a phosphor is often used - this would act very similarly to a fluorescent lamp that uses a mixture of phosphors coated onto the inside of the tube that each emit monochromatically upon excitation with UV light. The greater the variety of phosphors used the closer the net emissions may approach a continuous spectrum, but it will never be anything more than a facsimile of a continuum.

None of the light sources we use over our tanks emit a true continuum as does the sun or black body radiation in general. That would require a filament lamp where the filament literally gets as hot as 10,000-20,000 Kelvin degrees! haha (and a gigantic tank cooler too!)

I suspect any spectragraphs provided by the manufacturers of LED's or T5 or MH's that show what appears to be a continuum are greatly smoothing that graph (i.e. lying). since the mechanism by which these devices produce light is by its nature discrete.

 

[TexasReefer82]

I have also observed morphological abnormalities on a blue tenuis that is growing in a very bright spot in my tank about 16" directly under an AI Hydra 26 HD. I'll try to shoot some photos tomorrow morning of it. Interesting thing is that I also have 4x T5 bulbs over the tank. This may suggest that lack of a certain type of light is not the issue presuming that T5 lighting is completely sufficient.

Just thinking... could it be that an extremely intense and narrow wavelength range of the blue LED light drives abnormal growth?