With or without Zooxanthellae

[invincible569]

Everyone has seen bleached corals and once they are bleached, they loose their zooxanthellae or it becomes translucent that helps a coral grow to the point that without this symbiotic algae, growth rates are 1/10. Thats a huge difference! My question is.. why cant this algae jump over to another coral if they are inches away from each other helping the coral that is bleached? If its genetics, then how did the algae get to the coral in the first place?

[invincible569]

And also... if zooxanthellae wasnt present, then photosynthesis wouldnt need to occur as the algae is the only one who benefit from it. So why cant the coral survive without sunlight? The rate of calcification would be minimal, but should still survive. Thats why in a more shaded area, the zooxanthellae is denser because of the low concentration of zoox's. But still doesnt answer my question.

[G.Alexander]

Zooxanthellae are photoautotrophic dinoflagellates. They occur independently in open water where they solely exists without a host, carrying on photosynthesis and taking from the water whatever is required for life processes. Zooxanthellae enter corals through ingestion by the coral's polyps. Once within, they are incorporated within the second tissue layer (the gastroderm) where they proceed with their photosynthesis. In coral species that produce planulae, the zooxanthellae are passed on by the parents to offsring.

http://www.reefs.org/library/talklog/l_ho_030898.html

G.Alexander

[wasp]

zooxanthellae can be "harvested" from the water by corals, and anemones can do this also. The algae benefits from the photosynthesis, but surplus sugars are released which are then available for the coral. This energy is required by the coral to survive.
How I understand it anyway, the reason coral may be darker in the shaded area, is that in a brightly lit area less zooxanthellae are required by the coral to perform the required amount of photosynthesis due to them having more light. Hence the area is lighter.

[invincible569]

Good information guys!!

So what you are saying is that if we bleach a coral purposely, we can change the color outcome of the bleached coral to whatever algae it ingests?

[G.Alexander]

Edward, this would assume the colour which we can see with our eyes is caused by algae. However pigments also play a big roll in coloration & corals.

The sugar which is produced by the zoox is necessary to keep the coral alive over a longer period, not sure if this is the only mechanism why corals, which normally contain zoox, can not live without them.

This all will work with corals they get sunlight, but there are deep water reefs they do not get any light and this corals can live without zoox.

Aquarist Tridacna farms work in the way you told. They spawn the clams and put the larva in a container which contains mixed meat of their colourful clams. The zoox which are coloured are picked up by the larva to host them in their own meat where they reproduce.

G.Alexander

[Orion76]

So what you are saying is that if we bleach a coral purposely, we can change the color outcome of the bleached coral to whatever algae it ingests?

Edward, you might find this thread interesting:

http://reefcentral.com/forums/showth...hreadid=616742

[invincible569]

Wow! So its possible that it can be done! Maybe we are too early in time to try this? Especially since we cant even get our corals to spawn like we can with clams.

[invincible569]

Edward, you might find this thread interesting:

http://reefcentral.com/forums/showth...hreadid=616742

So we are right on track with our thoughts. I also felt that zooxanthellae was brown or green and its surroundings are what gives the color just as coralite posted with his macro pics earlier.

But back to the original question, what if we could change the colors of our corals by ingestion? No need to go out and find those beautiful colors when you can make it yourself.

[Orion76]

I think the type/color of pigments produced are determined genetically and can't be changed, we can only encourage the coral to produce more of it to make the colors more intense.

[invincible569]

I think the type/color of pigments produced are determined genetically and can't be changed, we can only encourage the coral to produce more of it to make the colors more intense.

Right. And you are right on track, but what Alexander said is that when a polyp matures and starts to make it calcerous skeleton, then it will ingest zoox's from out in the open water. If we could control this, we could add a superman red danae color to a coral dont you think? Do you see where I am getting at?

[Orion76]

I don't think that would work because ingesting the dinoflagellates will not change the coral's genetic program to make a certain color pigment. The dinoflagellates themselves are shades of brown.

[invincible569]

There are two parts to this.. the algal cell and the algal pigment which may have nothing to do with the coral and its genetics. See what I mean?

[Orion76]

I'm affraid you'd be limited to different shades of brown.

[Orion76]

Where's Gary when we need him