Coral Decalcification/Morphological Changes

[Nano sapiens]

Over the past 2-3 years I have observed an interesting phenomena. In response to increasing light intensity, a specimen of Pavona maldivensis has changed it's form from a flat plate to a mound that follows the conture of the underlying rock structure. The question I have is how does this coral achieve the transformation? Does it create a localized acidic condition that promotes partial decalcification? Once decalcified, does gravity and flow cause the weakened skeleton to gradually 'droop' and then recalcification occurs to reattach the coral to the underlying substrate and restrengthen the previously decalcified area? Questions, questions...

Calcification in photosynthetic corals has been often studied, but I can find precious little information regarding self-imposed decalcification used to produce morphological changes in coral. I have to wonder if this is an important facet of coral adaptive behavior that has been largely overlooked and understudied.

Is anyone aware of scientific studies carried out in this area?

 

[Randy Holmes-Farley]

I have never heard of any corals intentionally dissolving any part of their skeleton, but that doesn't mean it cannot happen.

I'm also having a hard time understanding what exactly you observed and why it would require skeletal removal. The plate itself bent over time, as opposed to just growing in a different way?

 

[Nano sapiens]

The 'Plate' was a 2" disk and as lighting was increased the rim growth changed to and went downwards (as would be expected). The strange part is that the original 2" disk is now completly missing from the specimen and has been replaced by a full 3/4" half-dome that now hugs the undelying live rock.
I would expect that the original 2" flat plate should still be somewhat recognizable if there was no skeletal morphing.

I don't have nice, closeup pics but the plate form of the maldivensis from 2-3 years ago is clear (top bleached-tan coral, slightly to the right). The 'Plate' was a 2" disk and as lighting was increased the growth changed to and went downwards (as would be expected). The strange part is that the original 2" disk is now completly missing from the specimen and has been replaced by a full 3/4" half-dome. I would expect that the original 2" flat plate should still be somewhat recognizable if there was no skeletal morphing.

I don't have nice, closeup pics but the plate form of the maldivensis from 2-3 years ago is clear (top tan coral, to the left) and the downward growth is starting to show:

And the same coral today that is composed of hills and valleys (the coral position appears a bit different, but that's only because the rock orientation was changed somehwat over the years):

I am open to the interpretation that the coral growth has created an optical illusion suggesting skeletal morphing, but the transformation is quite extreme when viewed in person.