[Coral-List] disease of Diadema mexicanum

dfenner at blueskynet.as dfenner at blueskynet.as
Tue Jun 2 18:23:56 EDT 2009

It looks to me like Esther Peters message didn't get through, so I'm going to
try to see if I can get it through.  It struck me that the symptoms sound much
like those of the Diadema epidemic in 1983 that spread throughout the
Caribbean.  No one took samples then, and so the pathogen has never been
identified.  So it is important to get samples of a disease like this.  Also,
people other places along the Pacific Coast of the Americas might keep a look
out in case this thing spreads.  Doug Fenner

Dear Francisco,

I have studied the histopathology of D. antillarum, and I am copying two
investigators at the University of Massachusetts at Boston who are interested
in examining the disease resistance of Diadema, in case they are not on the

If you can find specimens that are ill (not completely dead, or even appear to
be healthy), it is important to immerse them in a fixative solution containing
1 part 37-40% formaldehyde and 9 parts ambient seawater (preferably filtered). 
This is a basic fixative for light microscopy.  For complete diagnostic workup,
we would also need samples for microbiology and molecular studies, but I don't
know of anyone who might wish to take on those studies right now.  I have a
small histology lab and could process a few of the fixed samples (if anyone
else out there wants to do this, please do!).

Take a photo of the specimen before you collect it in a covered bucket, bring
back to boat or shore so you have a record of its condition.  Holding the
specimen carefully (with tongs), use scissors to snip off the long spines (like
giving it a "haircut"), then cut around the base of the Aristotle's lantern and
make at least a couple more incisions through the test so the fixative will
penetrate.  If you can put each specimen in a Liter-size jar or 4 L-size
resealable bag, then fill it with the fixative solution, that would be best. 
After you have them fixed for a few days, then you can consider how to ship
them to a lab to process them (I can provide further instructions).

Esther Peters, Ph.D.
Assistant Professor
George Mason University
Department of Environmental Science & Policy

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