Zooxanthellae and Pigments

Speedy · 02-02-2005, 07:17 AM

http://nr.stic.gov.tw/ejournal/Proce...n4/150-158.pdf

Here's an interesting document I found that shows that in coral bleaching Zooxanthellae are released. *It also states that bleached coral might not be dead. *

And that heat is major issue in coral bleaching. *Hmm this is getting interesting.....

They kept their acros under 80 m mol photons m–2 s–l during the experiment. What kind of lighting do you suppose they used to achieve this?

mojoreef · 02-02-2005, 03:43 PM

Ok David let have some fun!!

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Here's an interesting document I found that shows that in coral bleaching Zooxanthellae are released. It also states that bleached coral might not be dead

Yea but the percentage of recovery from bleaching is very low. The expulsion of zoox is an internal function of the coral to try to survive. It releases a heat stress enzyme that causes the zoox to bail. This happens in temps close to 30 C, technically the coral is still alive but having dumped the source for 98% of its food its on the way out. Now corals can retrieve zoox, but 99% of the time they cant do it fast enough not to starve.
Lighting didn't really pertain to the experiment you listed it was more of a inject warm water until the coral bailed it polyps.

Mike

mojoreef · 02-02-2005, 04:00 PM

Ok lets get into how it works first and then we can relate it to the lighting that is available.
Corals have Zoox which is an algae, actually they are dinoflagellates. they are the same as the nasty ones in our tanks. With in this dino are pigments. A series of chlorophyll’s which are green and carotenoid peridinin which is yellow. (yellow and green make??? brown, thus most corals are brown) now these pigments are basically chemical molecules that possess the ability to absorb visible light photons. and so the process starts. The energy of the light photons are captured by these pigments and transfered through a system called ETS (electron transport system). and eventually end up in a reaction center, which leads to the formation of ATP and NADPH . ATP is the food (Hmm andrenlintriphosphate??? (sp). and nadph is reducing power. both form organic compounds the coral can use as food.
Now the amounts of these pigments in corals is not a carved in stone thing, they can have more chlorophyll’s and less carotenoid's or visa visa and this can influence the color of the coral and/or clam. So how does that influence the light we use??? most of the pigments chlorophyll have a strong ability to gather light in the blue and violet range. the other more dominant pigment carotenoid peridinin mostly absorbs blue light waves, but does absorb violet and a tiny bit of green. So you make the call on the K of the bulb you wish to use (or combination).
So now lets move away from the algae that is providing food and take a look at some of the actual colors of the corals, because as we know not all corals are brown (thank God).
Also with in the coral are more pigments. they have a variety of different purposes and requirements. they reside with in the tissue of the coral itself. Now these pigments do not have the ability to transfer light energy, but it has been found that in very deep waters they ave the ability to alter particular color wave lengths. This is done by absorbing one color and the fluorescing a color the coral can use. SPS or shallow water corals produce large ammounts of pigments under high lighting intencity. So lets get into the meat of it.
Most pigments in coral tissue are called pocilloporin and are categorized as either Brightly Colored Low Fluorescent Pocilloporins or as Highly Fluorescent Pocilloporins. 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. Most of the highly fluorescent variety act as UV protectorants. protecting the coral and algae from UV's and to much light. the lower flourescent types tend to help the Zoox pigments convert uv and /or violet light into something usable.
these pigments absorb light basically with in the zone of 400 to 620 nm. violet to blue to some green and some yellow and some red. they absorb those light but fluoresce different colors back out. the colors the fluoresce out are the colors we see in our tanks.
So conclusion...sorta. most of the light waves corals use for growth are in the range of blue and violet. this is for food but not necessarily the color of the coral. the pigments inside the corals tissue, have a broader range of absorption and emit a different color then they absorb (usually). but it has nothing to do with their feeding process.

Mike

JohnO · 02-02-2005, 05:05 PM

Mike,

I almost bet you couldn't read that out aloud with a mouth full of plums:-)

Jokes aside, and dealing with your conclusion only at this stage, isn't it also correct that the reason that " most of the light waves corals use for growth are in the range of blue and violet" is because it is only that spectum of the sunlight that penitrates the water to the depth of the coral?

So in reality it is not the coral requiring that spectrum but rather the coral making use of the spectrum that is available?

I am only referring to coral feeding BTW

John

mojoreef · 02-02-2005, 05:56 PM

[quote]Jokes aside, and dealing with your conclusion only at this stage, isn't it also correct that the reason that " most of the light waves corals use for growth are in the range of blue and violet" is because it is only that spectum of the sunlight that penitrates the water to the depth of the coral? [/quoteTo a point John, your not taking the dynamic nature of the coral into play though. Pigments are protiens and the coral ultimately controls dominance. The coral has the ability to take a different light wave and covert it (or flourece it) to a more usable wave. Also most sps type corals live in depths where most light waves penetrates.

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So in reality it is not the coral requiring that spectrum but rather the coral making use of the spectrum that is available?

No it needs the proper spectrum or waves. Now it has evolved over time to take advantage of what is available, but with out the proper spectrum it wont work

Mike

Craig Manoukian · 02-03-2005, 07:20 AM

What is exocytosis?

Good artcle!

mojoreef · 02-03-2005, 09:10 AM

it is mechanism by which cells can secrete molecules like proteins

Craig Manoukian · 02-03-2005, 12:26 PM

Thanks Mike, no biology dictionary here!

Speedy · 02-03-2005, 01:11 PM

It's true that once the calcium enzyme is released within the coral the discharge of zoox is triggered, however, with the active tenticles still moving on the corals is it not possible for it to collect plankton? Maybe if say a food storm took place, if the water was temporary clouded by a high concentration of phyto or zoo- plankton, Would the coral be able to capture, feed, regenereate zoox and once again survive? The other thing I see is that if the zoox algae can be found free floating in the ocean what's to say we don't have it in a bottle someday and help our corals gain a higher volume of zoox.

I guess the first step would be to see if once the calcium based enzyme was released, it also caused irreversible damage to the coral.

Ok then the Pocilloporins... do you think that the size of them has anything to do with the particular wavelength of light they absorb? If not what mechanism on them does determine this? Is it the Chlorphylls or the carotenoid peridinin? I got that it's not the zooxanthellae that needs the light it' s the Pocilloporins, right?

mojoreef · 02-03-2005, 02:53 PM

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It's true that once the calcium enzyme is released within the coral the discharge of zoox is triggered, however, with the active tenticles still moving on the corals is it not possible for it to collect plankton? Maybe if say a food storm took place, if the water was temporary clouded by a high concentration of phyto or zoo- plankton, Would the coral be able to capture, feed, regenereate zoox and once again survive? The other thing I see is that if the zoox algae can be found free floating in the ocean what's to say we don't have it in a bottle someday and help our corals gain a higher volume of zoox.

Dave its not a calcium enzyme, its more of a protien based one. In answer to your question though sure, but its a real tough road, the coral would still have to repopulate its zoox and that could take a very long time based on its size. Corals that have bleached continue biz as normal but remember sps type corals are only set up for capturing 1% of their food, tought thinng to expect them to do when thier so stressed already.
I know marine biologists that strip corals of thier zoox and repopulate them with different strains for experiments, so it can be done..at least under lab conditions.

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Ok then the Pocilloporins... do you think that the size of them has anything to do with the particular wavelength of light they absorb?

No

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If not what mechanism on them does determine this?

Each protien pigment works with a range of light waves, what ever light wave is dominant will tell you which pigment becomes dominate in the coral.

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I got that it's not the zooxanthellae that needs the light it' s the Pocilloporins, right?

Close. Zoox are algae that has pigment as part of their body that aid it in the capture of photons (light energy). these pigments are chlorophyll’s (green to our eyes) and carotenoid peridinin ( which are yellow) they have so much of these pigments in thier make up that they blend the color and look golden brown to our eyes.
YOu can translate this to a coral that is fertilised (lives in nutrient laidened water) are almost always brown. The reason is that the zoox population has increased so much that it covers the other pigments in the coral.

Mike