[Coral-List] Meandrina meandrites Bleaching, Boynton Beach, FL

[Judith Lang/Lynton Land]

Dear Coral-Listers,
During the first half of the 1990's, the major sources of mortality for 
brown colonies of Porites astreoides at ~18 m on the North Perry Reef, 
off  Lee Stocking Island, Exuma Cays, Bahamas, were endolithic and 
epibenthic sponges, but "unknown" was also pretty common (as described  
by Shelley Anthony, myself, and Bassett Maguire, 1997, Proc. 8th Int. 
Coral Reef Sym 2:1789-1794).  Unfortunately the huge bleaching event of 
1998, and also, I suspect 1999, proved lethal to most of these 
colonies, along with many other corals on this reef.

We shouldn't lose other opportunities as still exist elsewhere to 
seasonally collect tissue samples of organisms that exhibit annual 
bleaching for histopathological examination, as suggested by Esther 
below.
Judy L.

On Oct 5, 2004, at 9:46 PM, McCarty and Peters wrote:

> The report of annual bleaching in Meandrina brings to mind an 
> observation I
> made years ago when Judy Lang brought a group of us to Lee Stocking 
> Island
> to examine colonies of the brown morph of Porites astreoides that had 
> been
> observed to bleach in the fall every year, then recover. We collected 
> a few
> bleached specimens for histopathological examination. The tissues were
> devoid of zooxanthellae, but still in good condition.  However, in many
> areas of the gastrodermis there were oocysts and released sporozoans of
> coccidia, the apicomplexans Steve Upton and I had described from corals
> (Gemmocystis cylindrus, J. Invertebr. Pathol. 47:184-193, 1986).  The
> coccidia were first discovered in coral samples that had bleached 
> patches
> of tissue and they specifically infect gastrodermal cells.
>
> We did not have an opportunity for further sampling, but I've always
> wondered whether the coccidia were there because the coral had 
> bleached and
> its immune system was damaged, therefore allowing the coccidia to 
> easily
> infect the cells OR was there something about the life cycle of the
> coccidia such that they infect the coral gastrodermis every autumn to
> complete their life cycle, causing temporary displacement of the
> zooxanthellae, then the symbiosis recovers after the coccidia have been
> discharged?
>
> I mention this because the vast majority of coral bleaching incidents 
> have
> not been examined using histological techniques and we might be missing
> something by not doing this.  I hope that someone will be able to 
> collect a
> few samples from these annual bleaching corals someday over the course 
> of a
> few years for histopathological examination. The bleaching of corals
> continues to present variations that suggest we still have much to 
> learn
> about the causes of bleaching and modes of recovery.
>
> Esther Peters, Ph.D.
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