[Coral-List] M. meandrites Bleaching

[Esther Peters]

Dear Ed and List,

That is really fascinating and brings to mind a similar phenomenon that 
Judy Lang was studying years ago at Lee Stocking Island in the Bahamas, 
regular autumnal bleaching of the brown morph of Porites astreoides.  I 
was fortunate to join her on a workshop trip and we obtained a few 
samples for histopathological examination.  The tissues contained many 
oocysts of a coccidian (identified only as Gemmocystis cylindrus in 
Upton and Peters 1986 from other corals).  This is a protozoan (Phylum 
Apicomplexa), whose relatives are known to parasitize and cause diseases 
in other organisms (for example, Cryptosporidium parvum in mammals). 
The gastrodermal cells contained few, if any, zooxanthellae.  Instead, 
the oocysts or sporozoites were present in the gastrodermal cells.  I 
wondered whether they might be replacing the zooxanthellae as part of 
their reproductive cycle, then they leave the coral host (for locations 
unknown) and the zooxanthellae repopulate the gastrodermis.  But further 
sampling was not possible.  The coccidian was found in Meandrina 
meandrites from Puerto Rico, submitted to me for analysis of patchy 
bleaching.

Determining whether the coccidian is in the bleaching Meandrina would 
require taking a small fragment (about 5  of the colony and placing it 
in a formaldehyde-based fixative for histological processing and 
identification of the parasite with light microscopy.  I would be 
interested in assisting in this effort if sampling occurs (perhaps 
someone else would like to check for zooxanthellae clade changes or 
something).  I see from your data that not all Meandrina colonies on 
Palm Beach reefs bleach like this, maybe up to 20-30%, so perhaps this 
is not just a temperature-, light-, or zooxanthella-related phenomenon?

Esther Peters, Ph.D.
Affiliate Professor
George Mason University

Etichscuba at aol.com wrote:

>  
>  
> The annual bleaching  cycle of Meandrina meandrites in Boynton Beach, Florida 
> has begun. The first bleached colonies  were reported September 30. The 
> bleaching and recovery cycle has been documented  for the last seven years.  
> Bleaching  begins within days after the Autumnal equinox and peaks at the end of 
> October,  with all colonies recovered by the end of December. 
> Tables, graphs and  photos can be viewed online @: 
> _http://hometown.aol.com/etichscuba/page1.html_ 
> (http://hometown.aol.com/etichscuba/page1.html)  
> Ed  Tichenor 
> Palm Beach County Reef Rescue 
> PO Box 207 
> Boynton Beach, Florida 33425 
> _Etichscuba at aol.com_ (mailto:Etichscuba at aol.com) 
> 
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>