Could we be missing the whole picture on photosynthesis??

[Kapital]

Are we missing the bigger picture??

I guess I'll start with... I know I'm not the most educated in marine biology and far be it from me to be an expert. If you feel I may be going down the wrong path, please drop you opinion below. This is a thread started to help the hobby. With that being said, I know there are many passionate people in the hobby, but please make sure to be curious to your fellow reefers. Also if you have any "experiments" or articles, I am a little of a nerd and would absolutely love to read them. I guess we should start with PAR vs. PUR.

PAR vs. PUR

PAR is defined as Photosynthetically Active Radiation. This is the total radiation, or light, being given at a certain level given to a coral.

PUR is defined as Photosynthetically Useful Radiation. This is the total of usable radiation, or light, being able to be used by a coral.

Many people tend to focus on PAR but being so fixated on this is actually not what is best for your corals. By using just PAR, you may be exposing your corals to more radiation, or light, that the coral isn't able to use by the zooxanthellae, which as we all know is what gives corals the coloration in corals. Because of the numerous types of zooxanthellae in corals, it is very difficult to actually and accurately generalize the SPS corals as a certain PAR level. I personally feel, it's all about exposing your corals to the right spectrum range vs the total volume of light. For example, it is like giving a ton of dark chocolate to a child. Although there are some parts of the dark chocolate that are healthy for a heart, the child will not be able to use the extra ingredients causing obesity and poor health.

Secondly, I am wondering if we have been focused on the visible spectrum and not the "active" spectrum. I'm noticing that people focus between (400nm-700nm). When in actuality there is a lot of UV-A and UV-B that are also involved with the photosynthetic process. I know that with reptiles you need to supply both UV-A and UV-B for support and bone growth/density. I am wondering if we can take this knowledge and information and apply it to corals. Upon further research about MH vs LED, I noticed MH actually produce some UV-A and UV-B, which might be why coral growth can be a little bit better. I have also put some articles I have read from advancedaquarium.com for those fellow reefer nerds such as myself.

All opinions are welcome just be constructive please. We are all here to have successful reefs and by enhancing our tanks just means we all get to share the love(corals). Looking forward to what people have to say.

http://www.advancedaquarist.com/2014/5/aafeature
http://www.advancedaquarist.com/2004/8/aafeature
http://www.advancedaquarist.com/2012/10/aafeature

 

[d2mini]

I just throw a mh over the tank and watch the coral grow without worrying about any of that. [emoji6]

 

[slief]

I will preface this by stating that I am not an expert on this subject but have read an awful lot on it. Addmittingly, I am still learning too. As such, the comments below are based on what I have retained (with my limited number of brain cells) after reading extensively.

First, One of the key reasons why we meaure PAR is because PAR meters are about the only practical tool we can use to measure light intensity. There are no PUR meters that are available to us mortals. I have an Apogee PAR meter myself and have found it useful. Unfortunately, from a coral perspective, PAR doesn't necessarily tell us as much as we would want to know about PUR. From a quality LED light perspective and even metal halide perspective, a PAR meter doesn't tell us everything either. This is because much of the useful light for coral falls into the 420nm to 500nm range where our PAR meters and even our own eyes have trouble reading or determining actual intensity. PAR meters are much more accurate at reading 420nm and below. These bluer/purple/uv spectrums just don't look all the bright to us or our meters. Many people cook their corals as a result of too much intensity because of this. PAR meters such as Apogee compensate for this with some built in math but it's not 100% accurate.

If you look at the chart below, it graphs natural sunlight on the reef and compares that to a Radium 20K metal halide which in my opinion is arguably one of the best MH bulbs out there. You will notice the peak in the 450nm range which if I am not mistaken falls into the UV spectrum. This happens to be where many but not all LED's fall short. Some LED's like Kessils, Orphek, Ecotech Radions and a couple others are stronger in that spectrum. I know Kessil in particular has gone to great lengths to insure there is a good amount of the UV spectrum. I'm sure the same can be said about the other Mfg's I mentioned. So while we do focus on PAR because that is the only useful tool we have as consumers to measure light output. Reputable light manufacturers do try to replicate the suns natural wavelengths and give us the ability to adjust our lights not only our liking but also provide enough of a spectrum mixture to insure that the peak areas for our corals needs are met with a higher count of LED's with that range.

If you look at the various charts below, you will see some common denominators.

Here is the graph showing natural sunlight on a reef compared to the Radium MH.

Here is a chart of the Kessil 360WE.. There are some adjustments that can be made to the light that is not reflected in this graph as the animation doesn't work with photobucket.

Here is a spectral chart of the Radion Pro G3.

Here is a spectral graph for the Orphek Atlantik..

Here is a spectral chart for the Tropic Marine Centre (TMC) Aquaray. The rep for TMC happens to be very keen (rightfully so) on the PAR vs PUR debate and the TMC fixtures like the ones I listed above also focus on more usable spectrums.

 

[lasteclipse]

http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/uv-rsults.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/420-results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/white-results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/blue-white-results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/red-results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/rate-results.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/carotene-absorbtion.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/carabien-corals.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/absorbtion21.png
http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/absorbtion3.png

You can see the different effects on the growth of Zooxanthellae Photosynthesis and the coral skeleton.
Red appears to be so good at growth, to good for the corals lack of protection from the light spectrum.

Here is the whole write up for those interested.

http://www.ukmarinelighting.co.uk/b...iciencies-of-led-lighting-on-aquarium-corals/

 

[lasteclipse]

http://www.ukmarinelighting.co.uk/b...iciencies-of-led-lighting-on-aquarium-corals/

 

[jminick2]

good stuff slief.

 

[lasteclipse]

http://www.ukmarinelighting.co.uk/blog/wp-content/uploads/sites/2947/2014/05/PAR-LEVELS.png

 

[Kapital]

Could we be missing the whole picture on photosynthesis??

Thank you slief so much for your response and d2mini definitely has a fail proof resolution. I have to admit I am fairly lost myself with all this UV stuff, but am trying my hardest to figure it all out. From what I've read in the articles I posted above are specifically focusing on UV-R or light spectrums above our visible sight range, mainly UV-A (320nm-400nm) and UV-B (280nm-320). Although I am aware that a majority of the photosynthetic process takes place within the visible spectrum, I had the idea of attempting to suppliment these UV-A and UV-B spectrums to enchanted coral bone density and growth. I am just wondering, mainly out of curiosity, if adding these spectrums will help. From what I saw on your charts above they tend to significantly slope down at 400nm. I am not sure if the companies that publish those results are just not using a great spectrometer to chart the led's or if they actually drop off that much. From what I read in the first article I posted, and also correlates to my second picture also from the first article, we have much UV-R growth potential as some of the 470-520 range.

If you can slief, do you mind posting any of his articles you found helpful, especially the ones from TMC? I'm kinda in the reading mood and am looking to read new stuff on this topic. I personally am all about the free exchange of knowledge and information.

 

[Panta rhei]

I thought coral's color is not from the zoox, but from the chromoproteins.
From a practical point of view, as far as I know, you use products like KZ Spur to actually expel zoox and let the underlying colors emerge.

 

[lasteclipse]

Biological Effects of Ultraviolet Radiation
It has long been recognized that UV radiation penetrates natural waters (Jerlov, 1950; 1976). Lewis (1995) noted that reef organisms employ several mechanisms to protect themselves from UV: avoidance, protection and repair. Obviously, many corals colonize areas with relatively high UV energy, so they have measures to protect themselves. Shibata (1969) found UV-absorbing pigments in certain Staghorn corals (Acropora) and Cauliflower corals (Pocillopora) as well as a blue-green alga. He speculated that a compound he called S-320 (meaning it absorbed UV energy at and around 320 nm) might protect marine organisms from ultraviolet energy penetrating shallow water. An even earlier researcher, (Kawaguti, 1944) speculated that some coral pigments offered protection against “strong sunlight.” Jokiel (1980) was perhaps the first to report UV as an important ecological factor on shallow water tropical ecosystems. Together, these papers along with others suggested that UV radiation could have deleterious effects on coral reef communities.

Perhaps the best single source of information on this subject was published in 1995. Entitled “Ultraviolet Radiation and Coral Reefs;” this work contains many papers on the effects of UV on corals, zooxanthellae, plankton, etc. Clearly, these present a convincing argument that ultraviolet radiation can have a major impact on coral reefs in many different ways.

What effects can UV have on coral reef organisms? A review of the literature suggests that the effects can be numerous and far-reaching.

Ultraviolet radiation can play a role in determining the survival of corals from their very beginnings. Baker (1995) reported that UV-A inhibited larvae settlements of the Cauliflower coral (Pocillopora damicornis); Gulko (1995) demonstrated that UV-B damaged the gametes of the Plate coral (Fungia scutaria) - possibly explaining why corals often spawn in darkness.

UV (or UV in synergy with high PAR, temperature, etc.) is known to inhibit photosynthesis. Glynn et al found a combination of high temperature (31°C) and high UV (A & B, 25-30% of direct exposure) caused a high mortality rate among Acropora vallida specimens (significantly more Pocillopora specimens survived this treatment). Lewis (1995) suggests that the zooxanthellae in the stony coral Montipora verrucosa may be damaged by exposure to ultraviolet radiation. Shick (1991) reported that the octocoral Clavularia (commonly called Star Polyps by hobbyists) exhibited a 50% decrease in photosynthesis when exposed to “high” levels of UV-A and UV-B. Hohlbauch (1995) reported the same effect on the Plate coral (Fungia scutaria). Gleason and Wellington (1992) used an underwater spectroradiometer to determine that increased dosages of UV could induce bleaching (loss of zooxanthellae) in the stony coral Montastrea annularis. UV was found to reduce the amounts of photosynthetic pigments and cause photoinhibiton (a reduction in the rate of photosynthesis) in the red alga Porphyra leucosticta (Figueroa et al, 1997). Donkor and Hader (1997) found that UV-B radiation caused bleaching of photopigments in the cyanobacterium Phormidium. The list of references could go on and on. It should be sufficient to say that ultraviolet radiation is potentially harmful to natural and captive ecosystems.

“Filtering” of Ultraviolet Radiation by Aquarium Water
Many aquarists believe that yellowing substances normally found in aquarium water will quickly absorb UV. We tested for UV transmission in aquarium water of several “colors” and report the results of two tests here. We used submersible UV probes, a sliding depth gauge, a Hach Color test kit and a “sunlamp” for the UV source. Aquarium water was “colored” with skimmate from a foam fractionator (protein skimmer) filtered through Whatman #4 paper. Figures 8 and 9 illustrate the water transmission properties.





As can be seen, UV energy falls off rather rapidly. However, under certain conditions (high wattage, reflector material with high UV reflectance, etc.), it is possible for UV-A radiation levels at the bottom of an aquarium to exceed UV found at the ocean’s surface.

Corals’ Natural Sunscreens
Many shallow-water organisms contain natural sunscreens to protect them from UV radiation. These include holothurians (sea cucumbers, Shick et al, 1992), algae (Shibata, 1969), corals (Shibata, 1969; Dunlap and Chalker, 1986; WuWon et al, 1995, 1997) and others (Dunlap, Chalker and Bandaranayake, 1988). These sunscreens are amino acids, more specifically, mycosporine amino acids (MAA’s). There are many MAA’s; each of these absorbs different UV wavelengths. For example, an MAA called S-320 absorbs UV at and about 320 nm; others have absorption maxima of 310 nm through 360 nm. These substances are colorless and block only UV – they allow visible radiation (PAR) to pass.

Factors Affecting MAA Concentrations in Coral Tissues
Increased UV levels (due to the thinning of the earth’s ozone layer) have lent an urgency to the study of UV-absorbing compounds. Kuffner et al (1995) analyzed the MAA content of several coral genera (Pocillopora, Porites and Montipora spp.). They found that MAA concentrations were inversely proportional to depth with its associated lower dosage of UV energy. (We must note that other researchers have suggested that water motion and other environmental factors may trigger the production of MAA’s.) Gleason (1993) transplanted brown Porites specimens from areas of relatively low UV energy to areas of higher UV and found these corals to exhibit reduced growth and possible photoinhibiton (he felt that UV energy in the range of 310-350 nm was responsible). He also found that corals could proportionally alter the amounts of certain MAA’s in response to UV levels. MAA’s may be obtained through the diet (as in the case of the non-hermatypic coral Tubastrea); it is also possible that zooxanthellae translocate MAA’s to the coral animal. In any case, the coral’s response to increased UV may be an increase in MAA’s within its tissues. This response is not instantaneous. (The analogy of a pasty-white sunbather trying to get a golden tan in one day is appropriate!)

In nature, corals exist in a relatively stable UV environment. If we were to graph diurnal UV doses, we would see a bell curve, that is, UV increases as the sun climbs toward its apogee and then decreases towards sunset. UV may peak during a given month (depending upon latitude) but these changes are incremental and predictable. Such is not the case in aquaria.

UV Depreciation of Aquarium Lamps
During the course of our investigations, we’ve checked the time-course UV output of many lamps. Figures 10 and 11 show this UV-A output of two metal halide lamps. As can be seen, one lamp’s UV output dropped over a period of time. Interestingly, UV output increased rather dramatically in the other lamp. Our point is that neither of these lamps offers a stable UV environment. Increases will occur either during normal operation of the lamp or when the hobbyist “suddenly” replaces the lamp. (We’ve found fluorescent lamps lose their UV output over time as well.)



This leads us to an important question – Is there a risk of eye damage from an aquarium using a light source with high UV output? We do not claim to be ophthalmologists and are not qualified to give medical advice. We can report the results of our testing. Using a glass aquarium, we found UV-A levels of up to 70% being transmitted through the glass above the water surface. Under certain conditions, we believe this level of radiation could exceed that of natural sunlight. Most acrylics attenuate UV quite well; however, comprehensive testing is required before a definitive statement can be made.

Coral Coloration and UV Radiation
It is quite popular to believe that increased coral coloration is a response, at least in part, to UV radiation. Our experiences indicate that some corals will turn green as a response to increased UV. However, we have observed many corals (especially Acroporids, Pocilloporids, etc) exhibiting vivid coloration when maintained for years under conditions of practically no UV (~1 µW UV-A; <1 µW UV-B). Figures 12 and 13 show two Acropora specimens maintained under such low UV levels (however, visible light – PAR – levels were quite high).

 

[rwb500]

I know that with reptiles you need to supply both UV-A and UV-B for support and bone growth/density. I am wondering if we can take this knowledge and information and apply it to corals.

could you please elaborate on that?

 

[slief]

Thank you slief so much for your response and d2mini definitely has a fail proof resolution. I have to admit I am fairly lost myself with all this UV stuff, but am trying my hardest to figure it all out. From what I've read in the articles I posted above are specifically focusing on UV-R or light spectrums above our visible sight range, mainly UV-A (320nm-400nm) and UV-B (280nm-320). Although I am aware that a majority of the photosynthetic process takes place within the visible spectrum, I had the idea of attempting to suppliment these UV-A and UV-B spectrums to enchanted coral bone density and growth. I am just wondering, mainly out of curiosity, if adding these spectrums will help. From what I saw on your charts above they tend to significantly slope down at 400nm. I am not sure if the companies that publish those results are just not using a great spectrometer to chart the led's or if they actually drop off that much. From what I read in the first article I posted, and also correlates to my second picture also from the first article, we have much UV-R growth potential as some of the 470-520 range.

If you can slief, do you mind posting any of his articles you found helpful, especially the ones from TMC? I'm kinda in the reading mood and am looking to read new stuff on this topic. I personally am all about the free exchange of knowledge and information.

I won't link to any of the articles from this individual because the guy quoted several of us here on the forum and threw us under the bus so to speak to further his blogs and promote himself further. He uses several blog sites under the guise of aquarium product blogs and all are biased with the sole goal of promoting the products he distributes. He literally copied and pasted several of our comments from this forum without our permission and placed those comments into his blogs in an effort to belittle several of us. While he seems to be great at internet marketing, I question his marketing and business ethics.

Quoting people in blogs without permission is not really a good practice. Especially if the people you quote have the ability to drive business your way. Hopefully that changes as TMC makes good products but the tactics mentioned abover certainly don't reflect well on them.

FWIW, much of what was covdered in the blogs by this person is the same stuff that is covered by Adanced Aquarist as well as others without the bias.

 

[Kapital]

Could we be missing the whole picture on photosynthesis??

Thank you for the information lasteclipse. It did answer a lot of questions I was having about the UVR. But I am now a little curious about the tests and am going to have to do some reading on it, which I'm actually excited about. Yeah I have found Advanced to be quiet helpful as well.

rwb500' I was informed that reptiles need UV-B to help with the ability to produce calcium more efficiently. Upon doing some further research, I have realized that what I was told was fairly generalized on the topic. Below is a little something I found and read up on before I decided to post this.

http://www.drsfostersmith.com/pic/article.cfm?c=6016&articleid=2376

 

[Kapital]

I can more than understand why you feel that way slief and thank you for being upfront about it. I also agree with you on reposting without permission.

 

[slief]

could you please elaborate on that?

A lack of UV B lighting can cause bone disease. Reptiles need the vitamin D that is obtained or generated from the UV B lighting for strong bones among other things. I am not aware of UV A having much if any benifit as far as bone growth goes.

Edit:
Here are a couple good reads on UV lighting and reptiles.
http://www.reptilesmagazine.com/Reptile-Health/Habitats-Care/Reptile-Lighting-Information/

http://zoomed.com/Library/ProductDBFiles/Reptiles and UVB.pdf

 

[lasteclipse]

Your Welcome. These kind of topics are difficult because you can't really compress the issue to sound bites are generalizations which are rampent in this hobby as well as others. Dogma exist everywhere, but pulling to gather the meta data can help yeild better results. It will be at the expense of time studying and experimenting however.

If I have time I would like to start a thread with all the Meta Data available on the subject. MH glass shielding doesn't really block all or even most of the UV but is typically positioned higher over the water level which helps further reduce it.

Since UV can and does alter RNA and DNA over time, sometimes the results are interesting but most times tragic with regaurd to studies of various animals and mammals.

The UV needed by most organisms varies for vitamin D and is dependent on the liver for it too become active and to what extent regulated. For this reason the government doesn't get into recommeneded sunlight exposure since it gets very complicated and varies per individual. Sound bites and story write ups by news would make it a dangerous "quick" read or bulb(sound bite).

 

[lasteclipse]

double post

 

[wseaton]

25, 15 and even 10 years ago UV radiation was universally accepted as a 'bad' thing in terms of coral growth because of the difficulties corals have in regards to regulating high energy photon absorption in the 350-400nm range. This thread seems to be one of those that lives in an alternate universe where UV as a bad thing wasn't already fairly common knowledge. Recently MH and T5 owners have renewed the morbid facination with UV because those products emit some degree of UV-A to a varying extent, and given common LED fixtures rarely have out-out below 400nm (most don't go below 440nm dominant ) it has become an emotional issue for them to differentiate themselves from the LED industry with whatever psuedo 'reef shop' science is available. Sorry, but this is the brutal truth.

Because of the numerous types of zooxanthellae in corals, it is very difficult to actually and accurately generalize the SPS corals as a certain PAR level. I personally feel, it's all about exposing your corals to the right spectrum range vs the total volume of light.

Zooxanthellae use common chlorophyll types, and absorption of spectral wavelengths for chlorophyll have been known for decades. I went through all those links and they simply reinforce 50yr old science that confirms those spectral weights. It's possible that some corals have some degree of external response to different wavelenths; warmer colors perhaps telling the corals it's in shallow water and to grow differently, but the main metabolic photon driver for Zooxanthellae is blue or preferably far blue light. 445-455nm light is the common dominant blue wavelenth for industrial MH, tube and LED emission, so 'it's all good' from a reef keeping perspective. MH should be shielded from UV-A emission. It's the unique presence of optics on LEDs fixtures that cause most of the bleaching problems (collimation), but nobody seems to want to address that issue because PAR readings are like computer over-clock benchmarks to the reefing industry.

Corals typically maintain several 'clades' of Zooxanthellae of which they are 'optimized' so to speak for water conditions such as temperature and nutrient levels. Hard corals want to keep a consistent rate of nutrient production, so when nutrient or lighting levels change they can eject one type of Zooxanthellae for another so as to keep those nutrient levels inline. Zooxanthellae symbiosis is a two way street. Over-reactive Zooxanthellae rob stony corals of nutrients and can quickly kill the corals, cause RTN, etc. Phosphate and nitrate for instance increases Zooxanthellae activity faster than hard corals can often regulate them causing all the common problems we know about. Lighting on the other hand should be delivered to corals as a constant so SPS have less variables to worry about. Changing spectral weights isn't going to help corals with that problem, IMO.

 

[rwb500]

rwb500' I was informed that reptiles need UV-B to help with the ability to produce calcium more efficiently. Upon doing some further research, I have realized that what I was told was fairly generalized on the topic. Below is a little something I found and read up on before I decided to post this.

A lack of UV B lighting can cause bone disease. Reptiles need the vitamin D that is obtained or generated from the UV B lighting for strong bones among other things. I am not aware of UV A having much if any benifit as far as bone growth goes.

thanks... I was worried that OP was drawing conclusions about coral based on reptile biology. I am still worried. This thread seems to be pure speculation. If you guys are curious about spectrum, there have probably been many threads here with actual science that you could read up on.

 

[oreo57]

Reef corals thrive under irradiances of solar ultraviolet radiation that would kill
or severely damage many forms of marine life (Jokiel1980). Additionally,
reef corals are metabolically dependent on intracellular symbiotic dinoflagellates,
commonly known as zooxanthellae, and will eventually
die if deprived of photosynthetically active radiation (PAR)
(Franzisket 1970).
Thus it would be advantageous for coral animal tissue to
be transparent to useful PAR wavelengths and opaque
to potentially damaging UV wavelengths.

http://onlinelibrary.wiley.com/doi/10.4319/lo.1997.42.6.1468/pdf

Increased UV radiation alone significantly decreased the Fv/Fm of all coral species, even at 27 °C.
There was a combined effect of temperature and UV radiation, which reduced Fv/Fm in all corals by 25% to 40%. During a long-term exposure to UV radiation (17 days) the Fv/Fm was significantly reduced after 3 days’ exposure in all species, which did not recover their initial values, even after 17 days. By this time, all corals had synthesized mycosporine-like amino acids (MAAs).

http://www.biolbull.org/content/213/1/76.short

Elevated temperatures and solar ultraviolet (UV) radiation have been implicated as recent causes for the loss of symbiotic algae (i.e., bleaching) in corals and other invertebrates with photoautotrophic symbionts.

http://link.springer.com/article/10.1007/s003380050073

http://link.springer.com/article/10.1007/BF00018071#page-1

UV radiation of most any kind has never been proven as a "health benefit" to photosynthectic organisms. That said I suppose one could infer a more "natural" env. with it present. At least for shallow corals..