Blue corals

Uri Frank frank at
Tue Jun 9 10:48:45 EDT 1998

Dear Coral Listers,

The described phenomenon of "blue corals" were observed in the northern Red
Sea by T. Lieberman, N. Shashar, I. Brickner, B. Rinkevich and myself in
"stressed" areas of the following species: Acropora eurystoma, A.
hemprichi, A. hyacintus, A. scandens, Cyphastrea chalcidicum, Fungia sp,
and Porites sp.. It may probably occur in other species as well, but there
it is masked by other pigments.Y. Barki observed Nephthea planulae turning
pink shortly before they died.

We have experimentally "stressed" colonies of the above species by
inflicting superficial tissue lesions and by putting colony fragments into
contact with intra- and interspecific counterparts. Reddish-purple
colorations of the involved areas were evident several weeks till months
later. This coloration was observed also around barnacles (in C.
chalcidicum), at the adge of the colonies' feet, near growing tubeworms
(e.g. Spirobranchus giganteus) and in tissues flanking naturally occurring
lesions. Furthermore, during algal blooms in the spring, many colonies
turned blue-purple. As mentioned by Y. Fadlalla, this phenomenon usually
does not cause partial or complete mortality of the corals and disappears.

We tried to extract the pigment using polar and non-polar solvents,
unfortunately without success. TEM preparations of "blue" tissues did not
reveal any unequivocal findings. The pigment is very stable even after
drying the samples. They remain blue for years. The pigment is definitely
in the tissues and not in the skeletons, as water-pick treatment completely
removes it.

Corals do not exhibit this blue clorations in the Caribbean as far as I know.

      -Uri Frank

Uri Frank
Zoolocical Institute
University of Jena
1 Erbert St.
07743 Jena

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