[Coral-List] Coralline Algae Lethal Disease AKA Goreau's Disease AKA Algae White Disease

[Thomas Goreau]

Dear Aldo and Coral List readers,

This slow spreading disease of encrusting red calcareous algae  
expands in circular lesions, but often stops short of killing the  
whole alga. It is distinguished by a white expanding ring, usually a  
millimeter or two wide, but in some cases up to a centimeter wide,  
with a sharp rim against the external pink or purplish encrusting red  
calcareous alga, The interior of the expanding circle is made up of a  
fine filamentous alga with a very distinctive olive green color.

I have documented it globally since 1991. I have many images on video  
and a few photographs showing it all around the Caribbean, Indian  
Ocean, Pacific, and South East Asia, but have never had the time to  
compile them.  However I have seen rare examples of it on much older  
photographs, so while it is not genuinely a "new' disease, it has  
certainly greatly expanded in the last 15 years.

I first noticed that this disease had spread very rapidly in the  
intertidal sea level notch in Negril, Jamaica, over a few months  
around 1991-2, and named it Coralline Algae Lethal Disease *CALD), by  
analogy with the Littler's Coralline Lethal Orange Disease (CLOD).  
Subsequently the encrusting reds in this habitat were overgrown and  
killed by fleshy algae as the area became eutrophic and algae spread  
all over the reef (NB: algae overgrew the reefs in Negril only in the  
early 1990s, after tourism development and NOT after the Diadema die  
off in 1983, or the earlier overfishing, as popular "phase shift"  
mythology claims).  Later Esther Peters mentioned it on her web site  
and called it "Goreau's Disease", a name I 'd rather see confined to  
something that is completely lethal and affects only politicians and  
their scientific servants. CALD is what Ernesto Weil and yourself  
have recently noticed and are now calling Algae White Disease.

I wrote a paper describing this around 1992 in a report on  
environmental changes in western Jamaica published in the proceedings  
of a conference held by the Negril Coral Reef Preservation Society. I  
don't have either a xerox or a scanned copy available, and the  
original is someplace in the mountain of boxes in my basement, that  
is to say, effectively unreachable. It took me a couple of years to  
convince Mark and Diane Littler that this was in fact a disease they  
had not noticed before, and they now agree that it is far more  
widespread than CLOD.

Since CALD is so widespread, and I don't have time to compile my  
observations, I'm now forwarding this to the coral list server to see  
if other people are also noticing it. I'm sure it is present almost  
every place where encrusting red algae have not yet been totally  
smothered by eutrophic fleshy algae, although it's frequency varies  
greatly from site to site.

Best wishes,
Tom

Thomas J. Goreau, PhD
President
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
617-864-4226
goreau at bestweb.net
http://www.globalcoral.org