Coral calcification

[Stigigemla]

I can see 2 teories of how the calcification in corals function.

1. The calcification is a product of the nutrient uptake of the coral animal.
2. The Coral animal is making the coral sceleton according to its needs.

1. Will mean that the amount of sceleton being produced is directly correlated to the nutrient uptake.

2. Will make it possible for the animal to create a thicker or thinner layer of tissue over new sceleton and replace lost tissue without "unnecessary" calcification on that spot or other places.

Is one of the teories correct or both or does it work another way?

 

[Reefing Madness]

 

[bif24701]

My feeling is and some reaserch has shown that coral Skelton formation is related to available bicarbonate, flow, and photosynthesis levels as long as all other parameters are correct.

Here Dana Riddle concluded that growth can be enhanced by raising the ALK and Flow with appropriate lighting in the coral he studied.

In closing he warned that there could be a danger with quick growth and high ALK. This could be the ALK burn. My thinking is that the skeleton is building so quickly that tissue growth can't keep up and leave the growth tips vulnerable.

 

[Stigigemla]

Yes i saw that in the article but i didnt react at that. I thought high kH burning was a result of too much light and kH related to circulation and organic nutrition causing the zoaxanthelle to produce hydrogen peroxid.
But maybe high kH can skew produktion of tissue versus sceleton. Is there someone who has read something?

 

[bif24701]

Yes i saw that in the article but i didnt react at that. I thought high kH burning was a result of too much light and kH related to circulation and organic nutrition causing the zoaxanthelle to produce hydrogen peroxid.
But maybe high kH can skew produktion of tissue versus sceleton. Is there someone who has read something?

I'm not sure that has really been studied yet and I think that was what he was going to look into.

 

[Stigigemla]

Bump

 

[jda]

From that I have ever read, there is 1) a balance between sugars from the zoox giving the coral energy, available carbonate, calcium, magnesium, strontium, etc. for the skeleton and then 2). also enough N and P to build new organic tissue to cover the skeleton along with more sugars for energy, but not so much N and P to slow down the cellular processes. The zoox comes along later to populate this new tissue - white or different colored growth rings and tips.

The really crazy thing is that 1 and 2 act independently of each other and that corals can calcify faster than tissue can be made. This is not a huge thing in the ocean, but it can be in our tanks.

Burnt tips are usually when N and P are driven below seawater levels to truly growth-limiting levels but light, carbonate and calcium are widely available. Usually with higher alk, good lighting and N and P driven low with media and chemicals. Without higher levels of N and P to impede calcification and lots of carbonate, the skeleton grows fast. However, with growth-limiting levels of N and P, the organic tissue cannot grow and the skeleton literally grows out of the tissue body. This was common back when a few people were trying to run true ULNS tanks (not natural or Zeo, but lower), or messed up with too much carbon dosing, GFO or other media. I see less of this now. Keeping up high levels of fish feeding or keeping alk near 7 can keep this from happening... or both is good.

There is light burn too, which is different.

 

[Stigigemla]

Thanks for a good answer. Naturally have I read all of that earlier but never combined it that way.
It would be interesting if You have any views of tissue repair as in question 2?

Can it be possible for the animal to create a thicker or thinner layer of tissue over new skeleton and replace lost tissue without "unnecessary" calcification on that spot or other places?

As I have observed SPS never grow over old wounds like for instant from flatworms.
But maybe someone has a method?

 

[jda]

I have never seen anybody specifically address repair, but in a few other places, there is stuff thrown out about repair as it relates to what they are specifically addressing. It appears that most complex hosts can recycle N and P for their symbionts to use for repair and regeneration of tissue. This does not appear to be able to last forever, but for the most part, the corals mostly need new building blocks (N and P) to grow and not so much to just survive. This is an adaptation to living in areas devoid of massive amount of available stuff - like open ocean reefs.

I saw this once in an essay/study on zoox expulsion from bleaching events. What makes them so dangerous is that the acropora literally spent their whole lifetime accumulating those building blocks and now they just got expelled and are gone forever. It is really hard for the corals to capture enough to rebuilt to where they were before. Eventually, they die since they cannot gather enough to rebuild the zoox to their old levels to provide them energy. I am mostly speaking towards acropora since we are in the SPS forum.

It is easier for acropora to just get a little bit here and there to grow.

Again, only references and bits and pieces in other things... most have come from some books and even a few presentations at reef shows. I saved a few links since I had this discussion with Lasse a while back and he wanted to read more. Most of what I have seen is in some books and over many years, but this is one that is on the web.

Together with an efficient recycling of coral metabolic waste products within the holobiont, this symbiosis thus enables efficient utilization of nitrogen compounds from surrounding seawater.

Nitrogen cycling in corals: the key to understanding holobiont functioning?

Corals are animals that form close mutualistic associations with endosymbiotic photosynthetic algae of the genus Symbiodinium. Together they provide t…

www.sciencedirect.com

I have seen acropora grow over dead-dead areas, but it is SLOW. In the case of burnt tips, I have seen them grow over the burnt area, but it can take years it seems. However, if you break off the dead area down to live tissue, it will heal and regrow in a few weeks, if healthy and thriving. This is just from observation. I have never seen any direct or indirect mention of this in any books or articles that I can substantiate.