Quote:
Originally posted by Casey
Shirley clip that baby I have done it successfully make sure you clip all of the white off, it will grow back here is one I have clipped. Casey
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I believe Casey's specimen in the photograph is actually an
Acropora spp., it is different in both morphological and growth characteristics from
Hydnophora rigida and related spp. One of the great things about
Acropora spp. is that due to their lack of effective allopathic defenses and ineffectual nematocysts for anything short of prey capture, they use their incredible speed of growth as a means of outcompeting the surrounding corals and related Alcynonians. This same speed of growth is responsible for the white tips that are seen in Acroporiids, as their growth is so rapid that the zooxanthellae are not capable of reproducing fast enough to keep up with the axial corallite development. In [Acropora spp.[/i] this is a sign of good growth conditions. In
Hydnophora spp. it
can be a sign that either some neighboring spp. of coral with potent sweepers is stinging it at night (especially if there is a potential culprit on the side of most of the damage), shipping damage (you said it was an old specimen, but moving it or brushing up against it or handling it to move it could do this as well), the presence of allopathic substances in the water column (i.e.,
Sarcophyton spp. or
Nepthea spp. or related octocorals in the same ecosystem), potential predation by higher organisms (butterflyfishes or parrotfishes or
Diodontidae spp. of fishes, some mollusks/ seaslugs as well), prolonged exposure to the atmosphere, or too intense a light exposure (or just plain UV).
Hydnophora rigida usually needs pretty intense lighting, but must usually be acclimatized to it if it was procured from the usual LFS sources, but as you have pointed out, this specimen has been in the tank for a good while. Bulb changes can sometimes make these same responses occur, but this would usually be with MH or a large number of
VHO bulbs over a system. With all that said, some specimens of
H. rigida will display lighter, almost white tips when they are in a rapid growth phase (see photos on page 366-367 Vol.II of
Corals of the World, Drs. Veron and Stafford-Smith). These members of the genus tend to prefer bright lighting and moderate currents as opposed to most of the other members of the genus, which originate from murky lagoonal conditions or deep sheltered reef areas where they demonstrate much slower growth. There are some exceptions to this, as there is some variation within each specie.
This white area may be normal for your coral, but Hydnophora are also quite prone to bleaching events and may display
White Band disease as well. Check to see if there is bare skeleton or if there is a thin layer of tissue left on the surface of the skeleton. If it is bare skeleton, definitely clip the white sections off with a pair of wire cutters and paint the cut edges with iodine, possibly a 4 to 6 min iodine bath as well. If it is a bleaching event and the rest of the tissue seems fine, I would be undecided as to whether to clip off the old tissue or not. This is a slow growing genera as a whole, although cuttings of these will quite easily accept new locations and
VERY SLOWLY begin to encrust their base.
Without actually seeing the specimen, I would be irresponsible in recommending a treatment here, but this should give you some direction in making a decision for treatment, if indeed treatment is even necessary. A lot of info to digest here, I hope this helps you some. (btw, Casey, that IS a nice Acro...
)
(edit: after looking at the picture again, I think it looks olike bare skeleton
in the photograph and would definitely need the clip approach. tdw)
