Attachment of Fragments to the Substrate

[Anonymous]

Eric,
Hopefully, this will be something we will be covering as part of the course. If it is, I look forward to discussing this...

I have added a few different Acropora fragments to one of my tanks. I haven't used any sort of epoxy to attach the colonies to the live rock and merely stuck them in a hole or even layed them on the surface. I find they then spend the next week or so growing an encrusting base until the colony is secure. It is only after the colony is secure that I notice any growth from the axial corallites.

How does the coral "know" that it has to attach itself?
Would it still grow the encusting base if it had been firmly attached with epoxy?
Is the encrusting base a third type of corallite (in addition to axial and radial) or are they modified radial corallites?

I'm sure I will have more questions when we come to discuss this.

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ATJ's Marine Aquarium Site

 

[Anonymous]

You know, this is a terrific question.

Here are some of the best refs on the subject, IMO.

Highsmith, Raymond C. 1982. Reproduction by fragmentation in corals. Mar. Ecol Prog Ser 7: 207-26.

Highsmith, Raymond C. 1980. Passive colonization and asexual colony multiplication in the massive coral Porites lutea (Milne Edwards & Haime). J Exp Mar Biol Ecol 47: 55-67.

Highsmith, Raymond C., Alan C. Riggs, and Carla M.D.’Antonio. 1980. Survival of hurricane-generated coral fragments and a disturbance model of reef calcification/growth rates. Oecologia 46: 322-9.

Every reference on this sort of thing makes it obvious about changes on growth rate, reallocation of energy, etc. In other words, the coral will preferentially sap energy from reproductive structures first, then growth, and use it to maintenance/injury repair. Most studies on transplantation show normal renewed growth rates about 6 months after re-establishment. Up to a year in some. Axial corallites may even disappear or not form new ones during this time.

How does it "know"? Damifino. Same way it "knows" to produce an axial corallite. The miracle of life encoded in the DNA, I imagine.

Eric