Coral,algae,pigments,lighting

[jhnrb]

Stony Coral Pigments, Algae Pigments and Captive Lighting

BY: STEVE TYREE

Speaker's Biography

Mr. Tyree has maintained saltwater aquaria for 20+ years. Previous accomplishments included writing articles for Aquarium Frontiers, Das Aquarium, Koralle, Breeders Registry, Seascope and hobbyist newsletters. He has in the past posted numerous articles and essays on the Internet. Photographs have been published in The Reef Aquarium (Delbeek and Sprung), The Modern Coral Reef Aquarium Volumes 1-3 (Nilsen and Fossa) and Aquarium Corals (Borneman). Steve has also given Presentations to MACNA VII in Louisville, MACNA X in Long Beach, WMC 1999 in Vancouver and is scheduled for MACNA XIV in Texas. The company Dynamic Ecomorphology was started by Steve in late 1995. This company has produced 1000's of captive grown fragments for the retail market. Consultation has been provided by the company to exporters shipping corals from wild habitats. About 8 species of corals have sexually spawned in the authors captive reefs. Steve also helped start the Scleractinian Stony Coral Challenge Series being run through the Breeder's Registry. Consultation has been provided to Ecosystems Aquarium, the inventors of a mud and macro-algae based filtration system. This consultation concerned the application of the system to support reef-building stony corals. Steve also manages the web site reeffarmers.com, which is a reef farmers web network. This network helps farmers distribute their products into a national market. Current interest include captive scleractinian stony coral research, natural filtration methods, environmental gradients Within tropical reef platforms, zonal reproduction, sponge research, ascidian research, bi-valve research and propagating captive grown corals, sponges and ascidians via fragmentation, budding or sexual reproduction. Steve has made presentations to various local clubs and associations located throughout North America. Books about reef building stony corals, living sponges, the new original environmental gradient captive filtration method, and sea squirts have been written by Steve and are self-published through DE Publishing. The company DE is conducting second phase research concerning a new natural method to maintain coral reef organisms within captive aquariums. This environmental gradient system relies on sponges and sea squirts to filter and process dissolved organics and pelagic bacteria. Steve is currently writing a book on reef building stony corals for Microcosm/TFH, while conducting further research for a second volume in the CMAT book series. That book will formally define a zonal based reef modeling theorem.

Presentation

Introduction

It’s good to be online once again through #reefs. This particular presentation will be a basic level introduction to some of the latest issues concerning the pigments within photosynthetic corals. There has been some important scientific papers published within the past few years concerning the pigments within the coral animal itself. A second topic discussed concerns the photosynthetic pigments within the symbiotic algae that reside inside the photosynthetic corals. There has been some important work on these Symbiodinium species algae that has been largely ignored by the captive coral market. A third topic discussed during this presentation concerns how captive lighting can be setup to establish a lighting environment that better provides the algae and coral light collecting pigments with the types of light or specific color of light that they can physically absorb. The performances of specific light bulbs are discussed based on published spectral testing conducted by Sanjay Joshi. I have personally just completed writing the manuscript for three chapters on lighting and pigments for a book on Stony Corals that will be published by TFH/Microcosms. The rough draft of the book will be completed by fall and should be printed within 1 to 2 years. The 3 chapters contain a total of 43,000 words, 65 figures and 31 tables. Needless to say we cannot convey all that information through this forum and I think that would also violate the contract I have signed with the book publisher. The first reviewer that has read through these chapters has noted that there are quite a few points that may be conflicting with some of the established conventional wisdom of the reef hobby. So, it is probably a good idea to set the ground work for that information through an introductory presentation such as this. It should be noted that a complete reference listing will not be given here, but will appear within the TFH/Microcosm Stony Coral book.

Section I - Light Collecting Pigments within Symbiodinium algae

Photosynthetic Corals first evolved millions of years ago without the ability to use or capture light. They were initially animals that derived almost all of their nutrition by collecting food items with their external polyp tentacles. Dissolved organics and some inorganic nutrients were also probably directly absorbed from sea water. At some point in their natural history, these simple invertebrate animals developed an ability to incorporate living single cell algae within their bodies. This relationship has progressed to the point where the coral can now control the algae to release a large percentage of the organic carbon compounds that are produced from the process of photosynthesis. In essence, the corals are now farming the algae and utilizing organic products synthesized by the algae. In return, the corals provide the algae with a stable environment and also supply nutrients that are required by the algae. The loss of this symbiotic algae, which can occur during Coral Bleaching events, can often lead to the death of modern day photosynthetic corals.

The algae within photosynthetic corals are single cell dinoflagellates that lack the normal flagellate or tail. Dinoflagellates are important members of the phytoplankton community that inhabits the shallow waters of the worlds oceans. Other then lacking a tail, the corals dinoflagellate algae possess characteristics that are common to other dinoflagellates. There are many different species of Symbiodinium algae that live symbiotically within corals, clams and other various invertebrate organisms. Some specific corals even contain multiple species or multiple strains of algae. Light is obviously a very important factor for photosynthetic algae. The process of photosynthesis involves light collecting pigments, which are basically chemical molecules that possess the ability to absorb visible light photons. The energy from these absorbed light photons is then transferred to reaction centers. We will not be discussing the inner workings of the photosynthetic process. The major concern during this presentation is the actual light collecting pigments within the algae. Without these pigments there would be no absorbed light energy for the photosynthetic reaction centers to process.

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[jhnrb]

Coral/algae/pigments/lighting (cont)

Photosynthetic pigments are the pigments that collect and process light energy which is eventually directly utilized by the photosynthetic apparatus. Symbiodinium algae also contain non-photosynthetic pigments which are typically used for photoprotective functions. Non-photosynthetic pigments include the carotenoids Beta Carotene and diadinoxanthin. The actual photosynthetic pigments within Symbiodinium algae can be grouped into two different types, which are the chlorophyll’s and the carotenoid peridinin pigment. The chlorophyll’s include chlorophyll_a and cholorphyll_c2. Chlorophyll_a has strong light absorbing capabilities within the violet/blue area of the light spectrum and can also absorb a significant amount of red light. Chlorophyll_c2 is utilized as an accessory photosynthetic pigment that primarily absorbs blue light. Chlorophyll pigments in general do not absorb much green light. This is why grass is colored green and the leaves of many trees are colored green. The other dominant photosynthetic pigment within Symbiodinium algae is the carotenoid peridinin pigment. Dinoflagellate algae, in general, possess a unique characteristic. Unlike most other photosynthetic organisms, the dinoflagellates incorporate the carotenoid peridinin as an accessory pigment within the photosynthetic light collecting antennae or apparatus. Peridinin is the most prevalent carotenoid pigment within Symbiodinium algae. For example, 77 % of the carotenoid pigments within the Symbiodinium algae from a Tridacna crocea clam were found to be composed of peridinin pigments. Peridinin was also found to be the highest percentage carotenoid pigment found within the algae of a Pocillopora stony coral. The peridinin pigment primarily absorbs blue light along with some violet and some green. Visually the pigment appears red and the combination of green appearing chlorophyll pigments and red appearing peridinin pigments, give the Symbiodinium algae their characteristic brown coloration.

The photosynthetic light collecting apparatus or antennae within dinoflagellates has a unique form and structure. Most photosynthetic animals utilize chlorophyll’s as their dominant photosynthetic light collecting pigments. The dinoflagellates however, incorporate peridinin pigments into the photosynthetic light collecting molecules that comprise their light collecting antennae. These molecules consist of peridinin-chlorophyll protein complexes. The first type of complex described within the algae was the water soluble peridinin-chlorophyll_a-protein called sPCP. The second type was the membrane bound chlorophyll_a-chlorophyll_c2-peridinin-protein called acpPC. There are a total of 4 known peridinin-chlorophyll protein complexes types that exist within the dinoflagellates. More then 80 % of the photosynthetic pigments within Symbiodinium algae cells were found to be peridinin-chlorophyll protein complexes. Symbiodinium pigment protein complexes are physically composed of 4 peridinin pigments that are combined with a single chlorophyll_a pigment. Three species of Symbiodinium were found to contain a peridinin to chlorophyll_a ratio of 4 to 1. Peridinin is the dominant photosynthetic light collecting pigment within the antennae molecules of these algae. Most of the pigment protein complexes that occur within Symbiodinium are composed of the acpPC pigment protein. This protein complex contains a chlorophyll_c2 pigment in addition to a chlorophyll_a pigment along with 4 peridinins. The acpPC pigment complex primarily absorbs blue light along with some violet. A less significant amount of red light is also absorbed. I have uploaded a low resolution figure of the absorption curve for this pigment complex taken in isolation. You can access it here. The less prevalent sPCP pigment complex primarily absorbs blue, violet and some green light. There is also a minor amount of red light absorbed. I have uploaded a low resolution figure of the absorption curve for this pigment complex taken in isolation. You can access it here. The affects of the absorption characteristics of these two photosynthetic pigment complexes is evident within the photosynthetic absorption spectrum for a Symbiodinium microadriaticum. An uploaded low resolution image here. The importance of blue and violet light can be clearly seen within these curves.

Section II - Light Collecting Pigments within the Coral Animal

The brown coloration within photosynthetic stony corals is due to the light collecting pigments found within the corals symbiotic algae. Photosynthetic stony corals can also possess many other colors that range from violets, blues, greens, yellows, oranges to reds and can include numerous combinations and shades of these primary colors. All these exotic colorations are due to pigments found within the tissue of the coral animal, and not within the symbiodinium. Coral pigments cannot directly transfer collected light energy to the corals symbiotic algae, but in some deep water corals their pigments appear to be modifying the existing light field by fluorescing one color or wavelength of light into another color or wavelength. Its been theoretically suggested that this may be an indirect technique where some coral pigments can be assisting the algal pigments with the collection of light. Shallow water stony corals have been found to possess pigments that are more intensely produced under higher light intensities. Some of these shallow water coral pigments may shield the coral from bright light of certain wavelengths, which can help prevent photoinhibition within the algae.

The first coral pigment identified was a pink colored pigment found within a Pocillopora damicornis stony coral. It was given the name pocilloporin. Pocilloporin primarily absorbs green/yellow (550-600 nm) light along with some upper UV-A. The density of the pigment is increased with increasing light intensity. It has recently been speculated that this pigments primary function may be to absorb yellow and green light that can otherwise be absorbed as scattered light by the corals photosynthetic algae. Under certain situations (strong light intensity) this type of scattered absorption of green and yellow light can occur. This pigment also emits or fluoresces a very small amount of (orange/red) light from 610 - 630 nm. Besides pink pocilloporin there are also many other types of pocilloporin pigments that occur within the photosynthetic stony corals. More recent research groups these types as either Brightly Colored Low Fluorescent Pocilloporins or as Highly Fluorescent Pocilloporins. The original pink pocilloporin pigment is a Brightly Colored Low Fluorescent Pocilloporin and to date it is the only identified coral pigment within that type or class. The Highly Fluorescent Pocilloporin pigments have the ability to absorb light with a specific wavelength and then fluoresce or emit this light into a different wavelength. Fluorescing pigments appear to have two distinct functions. Corals from strong light utilize these pigments to shield UV light and excess photosynthetically useable light away from the zooxanthellae. Corals from low light that possess fluorescing pigments can use these pigments to transform or fluoresce UV-A and violet light into more photosynthetically useable light.

A very important scientific paper was published in 2001 concerning Fluorescing Pocilloporin coral pigments. Titled "Major colour patterns of reef-building corals are due to a family of GFP-like proteins." It was published in Coral Reefs 19:197-204. The publishing of this paper was delayed by one year due to pending patent applications within Australia. I managed to acquire a copy of the manuscript about 6 months prior to its publication. This paper describes the actual molecular makeup of the fluorescing pigments within stony corals. They genetically identified 3 different types of highly fluorescent pocilloporins. One type primarily absorbs light from 310 to 380 nm (UV-B and UV-A) and then fluoresces this as light from 400 to 470 nm (violet/blue). Scientist refer to this as UV fluorescing pocilloporin, because the greatest absorption occurs within the UV area. Hobbyist should probably refer to this as violet fluorescing pocilloporin, because the visual appearance of the pigment is the fluorescing of violet light. Corals in shallow water can theoretically use this pigment to shield themselves from the harmful affects of UV light, while corals in deepwater can modify the UV-A light into light that is more photosynthetically useable. Unfortunately for the hobbyist, our eyes are not very good at perceiving violet light. Additionally, the stimulation of this pigments fluorescence requires producing UV-A/UV-B light over the reef. Violet Fluorescing Pocilloporin may be of little importance to captive corals.

A second type of highly fluorescent pocilloporin primarily absorbs light from 380 to 470 nm (UV-A, violet and blue) and fluoresces light from 475 to 520 nm (blue and green). Scientist refer to this as violet fluorescing pocilloporin, because its greatest absorption occurs within the violet area. Hobbyist should probably refer to this as blue fluorescing pocilloporin, because the visual appearance of the pigment is the fluorescing of blue light. There are a couple of theoretical possibilities explaining how corals may use this blue fluorescing pigment. They could be modifying violet light into blue light which is more readily absorbed by the peridinin pigment within the algae. There are also ways in which corals can link different highly fluorescing pocilloporins together. For example, a UV-B photon can be absorbed by a violet fluorescing pocilloporin. This would result in the emission of a violet photon which could then be absorbed by a blue fluorescing pocilloporin. This would result in the emission of a blue light photon.

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[jhnrb]

Coral/algae/pigment/light (cont)

The third type of highly fluorescent pocilloporin primarily absorbs light from 430 to 490 nm (violet and blue) and fluoresces light from 490 to 540 nm (green/yellow). Scientist refer to this as blue fluorescing pocilloporin, because its greatest absorption occurs within the blue area. Hobbyist should probably refer to this as green fluorescing pocilloporin, because the visual appearance of the pigment is the fluorescing of green light. Corals can theoretically use this pigment to shield themselves from excess photosynthetically useable light. This is done by the pigments absorption of blue and violet and its emission of primarily green to yellowish light which is less useable for photosynthesis.

Besides these three Highly Fluorescent Pocilloporins, there are also two other types. Yellow fluorescing pocilloporin primarily absorbs light from 440 to 500 nm (blue) and fluoresces light from 520 to 620 nm (green, yellow and orange). This pigment can theoretically be used as a strong light shield that absorbs photosynthetically useable blue light into primarily non-useable yellow light. The fifth type of Highly Fluorescent Pocilloporin is a Red/Orange Fluorescing pocilloporin that primarily absorbs light from 500 to 540 nm (green) and fluoresces light with wavelengths that are primarily orange to red. In many corals this red/orange fluorescing pigment can even be stimulated to fluoresce with UV, violet and blue light. It is currently theorized that different fluorescing pigment proteins are linked so that UV, violet and blue will eventually stimulate the red/orange fluorescence.

Highly Fluorescing Pocilloporins are the most common pigments found within stony corals. A recent study of corals on the southern Great Barrier Reef found that 97 % of the sampled corals contained medium or high concentrations of fluorescing pigments. These fluorescing pigments are often not visible to the human eye. It was also recently discovered that corals containing high densities of fluorescing pigments were less sensitive to coral bleaching that was induced by photo damage to the photosynthetic apparatus within the corals algae. I personally was curious as to why the Coral Reefs paper mentioned earlier was held up for one year due to a patent application. So I talked to an associate at the Arizona Cancer Center about the paper. It appears that knowing the molecular structure of these fluorescing pocilloporins may turn out to be very important tools concerning the administration of multiple drug treatments. Each drug within a multiple drug treatment can be given different fluorescing capabilities which will allow researchers to determine where the different drugs went. So the study of coral pigmentation appears to be developing new and important tools for human medicine.

Section III - Captive Lighting Applications

Just what does all this information about algal pigments and coral pigments mean to captive stony aquarists? The book on captive stony corals that I am writing for TFH/Microcosm goes into great detail about how the spectral output of specific light bulbs correlates or matches the spectral attributes of the various coral and algal pigments. I spend very little time analyzing how the spectral output of lower temperature bulbs (for example 5,500 K and 4,200 K) correlate with algal and coral pigmentation. This is simply because they correlate very poorly. Bulbs that emit large amounts of yellow, orange and red light will not stimulate the fluorescence of the Highly Fluorescent Pocilloporin Pigments. Bulbs that do not emit significant amounts of violet/blue/green light will not be providing the main wavelengths of light that is absorbed by the algal chlorophyll_a, chlorophyll_c2 and peridinin pigments. Chlorophyll_a can absorb some red light, but the 5,500 K and 4,200 K bulbs do not emit red light of the proper wavelength.

To help clarify the situation I have grouped useable captive light bulbs into 4 basic groups or types. They are Full Spectrum Green, Super Blue, Full Spectrum Violet and Actinic (Super Violet). The Iwasaki 6,500 K is the only bulb classified as a Full Spectrum Green bulb. This bulb emits the highest percentage of its light within the green and yellow parts of the spectrum. It also emits significant amounts of violet, blue, orange and red light. About 60 % of the total light emitted by this bulb is either green, yellow or orange light. That type of light is not primarily absorbed by the chlorophyll and peridinin pigments within the algae. The bulb does however emit significant amounts of violet and blue light which are primarily useable by the algae. This bulb could use a boost within its high energy blue part of the emission spectrum around 440 nm. Many aquarists have had success with the bulb and it is definitely useable. The very strong photon flux density emitted by the bulb helps to compensate for its spectral limitations. This bulb will moderately stimulate the blue, yellow and linked red fluorescing pocilloporin pigments. Green and red fluorescing pocilloporin will be strongly stimulated to fluoresce. A moderate amount of light emitted by this bulb can be absorbed by the pink pocilloporin pigment. The 400 and 250 watt versions of this bulb are both useable for shallow water stony corals. Many aquarists will use actinic fluorescents to help balance the green/yellow appearance of the bulb. It would be better to add blue light because the bulb already emits a significant amount of violet light.

The Radium/Osram 20,000 K and Sunburst 12,000 K are both classified as Super Blue bulbs. Super Blue bulbs emit the vast majority of their light within wavelengths from 440 to 460 nm (high energy blue). They also emit small amounts of violet and green light. The narrow emission of this bulb happens to be located within an area of the spectrum where chlorophyll_a, chlorophyll_c2 and the peridinin pigments can absorb and utilize the light. The vast majority of the emitted light energy from the Super Blue bulbs is photosynthetically useable by the algae. These bulbs can actually benefit from a boost within the violet area of the spectrum. Most aquarists however will be adding daylight fluorescents to counter the very blue visual appearance of the bulbs. These bulbs will intensely stimulate the blue, green and yellow fluorescing pocilloporin pigments. Red fluorescing pocilloporin will be moderately to strongly stimulated. Super Blue bulbs only provide a weak amount of light that can be absorbed by the pink pocilloporin pigment. The 400 watt version of the Osram/Radium and the 250 watt version of the Sunburst lamps are both useable for shallow water stony corals.

The Ushio 10,000 K and Aqualine Buschke 10,000 K are Full Spectrum Violet bulbs. The spectral output of these bulbs is characterized by a large emission of violet light along with a secondary emissions of green, yellow and orange light. As Sanjay Joshi noted these bulbs trick the human eye into thinking there are emitting significant amounts of blue light. The significant violet light emission will provide plenty of light for the chlorophyll_a pigments within the algae. These bulbs will really benefit from supplemental blue light. Full Spectrum Violet bulbs will moderately stimulate the fluorescence of the green, yellow and red fluorescing pocilloporins. They will strongly stimulate the fluorescence of the blue and linked red fluorescing pigments. These bulbs only provide a weak amount of light that can be absorbed by the pink pocilloporin pigment. The 400 watt version of the Ushio and Aqualine Buschke are acceptable bulbs, while the 250 watt version of the Double Ended HQI and Aqualine Buschke are also acceptable. Actinic bulbs or Super Violet bulbs are best used as supplemental lights for bulbs that are deficient in violet light emission.

The intensity of captive light is also an important issue. Due to space limitations I can only briefly cover the subject here. Most corals imported for the captive market come from shallow water locations. This does not mean that all corals imported are bright light corals. Some of these corals will come from shaded shallow water areas and they will be low light corals. However, the majority of imported corals will be strong light corals that expect from 700 to 1,200 micro Einsteins/square meter per second. Within the stony coral book I am writing for TFH/Microcosms I have constructed guidelines for establishing different light intensities. What I have basically done is define light intensities into 4 differentlevels that are: weak light; moderate light; strong light; and intense light. As a basic guideline, strong light is typically achieved with the use of 400 watt halides. Intense light is typically achieved with the use of 1,000 watt halides. Weak and moderate light levels can be achieved with 175 to 250 watt metal halides and power compact fluorescents. There are actually quite a few low to moderate light corals being farmed within captive systems. For example, I have been farming and distributing an Echinopora lamellosa that actually prefers weak to moderate light. It develops a very nice blue fluorescing pigment in weak to moderate light, but will loose the pigment in strong light.

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[jhnrb]

Coral/algae/pigment/light

Conclusion

My web site can be found at http://www.dynamicecomorphology.com . Those of you interested in purchasing books by Steve Tyree can access this web page. For learning about Steve's new all natural zonal filtration system, the following web page can be accessed http://www.dynamicecomorphology.com/gradient.htm,

Presentation Completed.

Questions & Answers

Its known that photosynthetic reactions have a range of radiation that is most effective, beyond that range, photosynthesis falls... Do you believe that the colored pigments within coral are more protective or sugar producing?

I think you are asking if the corals pigments are more important to photosynthetic production or phtoprotection. Anything that protects the algae from photo damage will in the long run increase photoproduction.

What are your thoughts on coral growth rate and health vs. color temperature of the bulb? Is there an "ideal" bulb combination for the reef tank in your opinion?

Although I did not have the time to cover the subject here, I actually recommend a combination of different bulbs to help achieve the more ideal spectrum. For example, Iwasaki 6500 K and Super Blue bulbs is good. 10,000 K and Super Blue are also very good. Believe or not the combination of actinics with 20,000 K is also very good, but may be way too blue for most reefers.

Physiologically speaking, the flourescing pigments you mentioned, do they occur prior to the zoox channels or behind them? It would make more sense adaptively to reflect fluoresced light back to the primary zoox without losing any given spectral character?

For weak light corals the FPG's (fluorescent pigment granules) are located below the zoox. They modify UV and violet light into light that is more photosynthetically useable by fluorescing it upward toward the zoox. Strong light corals have the FPG's located above the zoox so that fluoresced light travels upward and away.

Not lighting related, but how is stoney coloration affected by lots of nutrients in the water? Some gets more colorful, others get brownish?"

Studies have shown that elevated levels of nitrogen (nitrate) can lead to increased density of zoox. This causes the coral to appear more brown. I have also noticed that if the physical environment is not correct (weak current ad inappropiate lighting) the pigments will also fade. That was 'coral pigments' will fade.

Does MH lighting in general produce UV-A/B lighting or need to suppliment? What about the Iwasaki 6500 K bulbs?

There is a small amount of UV-A that is produced by single ended metal halides ( according to Sanjay's testing). Double ended bulbs of course emit way too much and need shielding. UV light can really only be used to fluoresce the Violet Fluorescing Pocilloporin. If you want to experiment with this pigment you can probably use a black light.

Danna Riddle is working with new light device that guides him to say that maybe we are using to much light in our tanks because corals use all the light that they need and after that everything is useless. Did you hear about his new work? how this sound to you?

I have responded to Dana first article about this in the online magazine AAOLM (Note: AAOLM is Advanced Aquarist Online Magazine, found at http://www.advancedaquarist.com). Check the message board concerning his article for some responses. There were quite a few difficulties with collecting the data and other reef specialists such as Borneman and Harker also had some issues. The problem with PAM Fluorimeters in general is that they were not designed with the peridinin pigment in mind. They're use on stony corals zoox has produced mix results.

What is the typical conversion efficiency per incident photon for these types of fluorescing molecules?

That is an interesting question. From what I have read there is a fluorescence for every absorption. Otherwise this could lead to a heat or energy problem within the pigment. Its possible that these pigments might also dissipate energy through heat and not always fluoresce. That is probably a good subject for further investigation.

Everyone is concerned about bulbs that generate a good deal of UV radiation (such as HQI), do you feel that the UV is a necessary part of the corals coloration/growth needs or is overall detrimental?

If you plan on releasing your stony corals into the natural environment (captive farming to replace natural populations) it would probably be a good idea to have them acclimated to strong UV exposures. For normal captive situations it may only be a concern when you are moving corals from lower light fields into stronger ones. Overall we have had good success in captivity without UV exposure, but if you want to fluoresce the violet fluorescing pocilloporin some UV light may be in order.

Do you endorse the release of captive specimens to the environment?

To replace a recently extinct species it is a very good idea. TO introduce a non-native species it is not a good idea.

What are your thoughts on the usable lifetime on the higher kelvin bulbs? Current thought is that the Iwasaki's are usable for 12-18 months whereas the higher kelvin bulbs need to be replaced every 6-9 months. Do you believe this to be the case?

That is true if you maintain a constant photoperiod throughout the lifetime of the bulb. When using Super Blue bulbs I recommend an initial photoperiod from 6 to 8 hours that is slowly increased to 11 to 13 hours by the end of the year. That will get you 1 years worth of use from the Super Blues.

How does current affect the coral pigmentation?

Corals from intense to strong currents have growth forms that require these currents. This is to allow the proper diffusion barrier to develop around the coral. If the coral cannot properly interact with the surrounding water environment its overall health will deteriorate. This leads to a loss of coral pigmentations.

In your talk tonight you referenced "shallow tanks." What would be considered shallow?

Sorry, I don't recall using the term. I did mention shallow water. According to collectors shallow water is down to about 12 feet.

Is it possible that the change in spectrum that increases production of accessory pigment is detrimental to the health of the coral and reduces growth?

A recent study found that corals with increased fluorescing pigmentation were better able to survive bleaching events. Now if a coral becomes more colorful appearing because it lost its brown zoox, that would not be a good thing. A healthy coral has both a rich brown coloration and an intense coral coloration (if the species can develop it). It appears the about 97 % of the shallow water species can develop these fluorescing pigments.

In part of your talk tonight you mentioned that fluorescence is directional. How exactly is fluorescence directional?

The word directional was not used, but was inferred. This question gets into a very complex part of the fluorescing pigmentation issue. Fluorescing pigments can be bound into fluorophores and chromatophores. They can also be present as just loose fpg's. Loose FPG's would not neccessarily need 100 % directional control. As long as some of the modified photons traveled upward, that would provide more useable light to the zoox.

One attendee writes: "I have had very little success with SPS under 12K 400w bulbs and when replaced with Iwasaki 6500K bulbs I have had success in the same set up. What are your thoughts on this?"

I take it you were using the Sunburst 12 K bulbs ? From what Sanjay has noted is that the 400 watt version has variable performance from a spectral output point of view. I did not recommend it in the talk. I did recommend the 250 watt version which had good spectral output. I should clarify that what I mean here by spectral output is also the intensity of spectral output. I have had good success with 20,000 K radium/osram 400 watt bulbs for more then 6 years now.

ETA of stoney coral book from Microcosm? Is this another edition of your Stoney book or completely new?

Steve Tyree - That book is a completely new book written strictly for maintaining stony corals in captivity. The original manuscript will not be completed until the fall. My guess would be early 2004.

Could you go a little deeper on your thoughts concerning the 250w DE bulbs?

I am waiting for Sanjay to publish spectral outputs from these bulbs. The PPFD or photosynthetic photon flux density from the bulbs appears to be very good for their wattage rating. But as usual I am also concerned about the spectral output. The light fixtures are also a bit pricey right now, but they really look awesome.

And the final question for the night as we're running late on the talk: What's your secret for a perfect bloody mary? ;)

LOL, you could try some fresh protein skimmer foam for a good head.

END.