[Coral-List] Set the Diadema loose!

Thomas Goreau goreau at bestweb.net
Sat Jan 19 10:03:26 EST 2008

Dear Martin,

Andrew Ross says that at Doctors Cave near Montego Bay, Trididemnum  
solidum and Echinometra occur in the same habitat, but are mutually  
exclusive, so maybe there is something to this.....

It will be very interesting to use your pet Diadema herd for targeted  
experiments! I really hope that they eat every bit of Trididemnum  
solidum that they encounter, but I wonder if it is just too toxic for  
them. One of our reef restoration sites, in Sint Maarten, has very  
dense Diadema populations, and there is Trididemnum solidum there  
too, but not yet too bad.....

Another place where you need to set your Diadema loose and see what  
they do, is on the slimy cyanobacteria that is taking over wherever  
there is much nutrients from sewage and other sources. SE Florida has  
vast patches of this killing corals , spreading outward from the  
sewage outfalls, and waxing and waning as they change the amount of,  
ummm, ordure (Jim, that's not a banned word yet is it?), that they  
pump out, as Ed Tichenor has definitively shown.

Wayne Hunte told me in 1994 that Diadema had recovered to around two  
thirds of their pre 1983 densities in Barbados, and you could see  
that they and the huge parrotfish everywhere (which Bajans don't  
eat)  got rid of the macrophytes but could not control the turf that  
was eaten and grew back every day. In the last 5-6 years (according  
to Angelique Brathwaite of the Barbados Coastal Zone Management Unit)  
the turf has disappeared, and been replaced by slimy cyanobacteria  
(not the same one killing SE Florida reefs and the areas around the  
dolphin pens in Cozumel, another species), and the Diadema have again  
disappeared. The parrotfish don't seem to touch the stuff, and I'm  
wondering if the new disappearance of Diadema is another plague or if  
they have been starved out because they won't touch the main algae  
that is there now?

By the way, despite much urban mythology, Diadema die off had nothing  
to do with the spread of algae over the reef in Jamaica, which was  
caused by eutrophication that coincidentally occurred spanning the  
Diadema die off in the Discovery Bay area, but which happened long  
before and long after in other parts of Jamaica:
T. J. Goreau, 1992, Bleaching and reef community change in Jamaica:  

Best wishes,

On Jan 19, 2008, at 9:04 AM, Martin Moe wrote:

> I might be able to do this, I have a brood stock of 19 large and  
> healthy Diadema and it would be possible to collect a bit of  
> Trididemnum and see what happens to it in the tank. The result  
> wouldn't be directly applicable to what might happen on the reef,  
> but it would be a clue. If I get a chance to do this, I'll let you  
> know what happens.
> Martin
> ----- Original Message ----
> From: Thomas Goreau <goreau at bestweb.net>
> To: andrew ross <andyroo_of72 at yahoo.com>
> Cc: Martin Moe <martin_moe at yahoo.com>
> Sent: Thursday, January 17, 2008 5:20:33 PM
> Subject: Re: [Coral-List] tunicates
> Echinometra does not go deep enough to be in Tridemnum habitat.
> I very much doubt the Diadema control hypothesis, but it would be  
> interesting to put some Diadema on a bit of Trididemnum and see  
> what happens. I hope Martin can try this.
> On Jan 17, 2008, at 3:29 PM, andrew ross wrote:
>> I'm not seeing this tunicate on Echinometra viridis
>> colonized/cleaned reef areas. Areas without this
>> urchin/with (plenty of) algae loaded with it. Diadema
>> control makes sense.
>> Also Echinometra areas have less/no boring sponges
>> either.
>> Andrew
>> --- Martin Moe <martin_moe at yahoo.com> wrote:
>>> I've been following the tunicate thread with great
>>> interest.
>>> Seems that what's needed to keep them under control
>>> would be an organism that
>>> actually cleans the rock, something that can scrape
>>> and feed on just about anything
>>> that is attached to the upper levels of the
>>> substrate, something that even if
>>> it couldn't actually consume the organism itself
>>> might be able to keep its
>>> growth in check and keep it from invading open
>>> substrates. Too bad that
>>> there isn't anything like that on the western
>>> Atlantic reefs today, at least
>>> not in numbers adequate to do this housekeeping over
>>> extensive areas. But wait,
>>> maybe Diadema could do that job, as well keep algae
>>> growth under control, if
>>> they were abundant once again.  Diadema may
>>> or may not have had an impact on tunicate growth
>>> when they were abundant, I have not seen any studies
>>> on that, but they
>>> were so critical in shaping and maintaining the
>>> ecology of these reefs over
>>> great expanses of time that their loss has
>>> implications for the reefs far
>>> beyond just algae control. There could be an
>>> interesting graduate thesis in such a study. Too be
>>> sure, return of Diadema wouldn’t solve all
>>> the problems facing these reefs in these perilous
>>> times, but if Diadema could
>>> be returned to the reefs, they would be an essential
>>> element to whatever ecological restoration
>>> of our coral reefs is possible.
>>> Martin Moe
>>> _______________________________________________
>>> Coral-List mailing list
>>> Coral-List at coral.aoml.noaa.gov
>> http://coral.aoml.noaa.gov/mailman/listinfo/coral-list
>> _____________________________________________________________________ 
>> _______________
>> Never miss a thing.  Make Yahoo your home page.
>> http://www.yahoo.com/r/hs
> 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

Thomas J. Goreau, PhD
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
goreau at bestweb.net

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