[Coral-List] Tunicate-killing coral spreading all across Caribbeanregion

Thomas Goreau goreau at bestweb.net
Wed Jan 16 17:56:29 EST 2008

Dear Alina,

This is a very interesting idea, but what could eat them, and why  
don't we see signs of them being chewed in the field?

In fact I've not seen any tunicate anywhere being chewed, even in  
Indonesia with the highest diversity of tunicates and fish in the  
world, where you would expect some predator would have evolved a way  
to exploit and abundant food resource. I hope someone can prove me  
wrong, because we need a lot more of such a predator.......

Tunicates seem to be very toxic, even the ones that are soft and seem  
to have no protection at all are not eaten. Some tunicates are known  
to have very high Vanadium contents, but nobody seems to know how  
general this is, or at least I don't.

Also, why would the worst infestations I've seen be in the Washington  
Slaagbai Park in Bonaire, which is about the most really strictly  
protected and local pollution free place in the entire Caribbean?

And since they are photosynthetic, they need full light exposure. You  
can clearly see they grow best on the top surfaces of corals so they  
don't make a good cryptic organism.

Best wishes,

On Jan 16, 2008, at 5:42 PM, Szmant, Alina wrote:

> My bet is that there is decreased predation on the tunicate.  They are
> usually chemically defended, and I have no idea what eats them.  Most
> tunicates and other fleshy inverts tend to be cryptic to protect  
> against
> predation.  Release from predation allows them to grow out in the  
> open.
> Caging studies published back in 80s (work by Day and others,  
> references
> not handy) showed this.
> I have also seen a high frequency of these mats especially growing up
> the columns of Montastraea annularis.
> Alina
> *******************************************************************
> Dr. Alina M. Szmant
> Coral Reef Research Group
> UNCW-Center for Marine Science
> 5600 Marvin K. Moss Ln
> Wilmington NC 28409
> Tel: (910)962-2362 & Fax:  (910)962-2410
> Cell:  (910)200-3913
> email:  szmanta at uncw.edu
> Web Page:  http://people.uncw.edu/szmanta
> ******************************************************************
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov
> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Thomas
> Goreau
> Sent: Wednesday, January 16, 2008 4:17 PM
> To: coral-list at coral.aoml.noaa.gov
> Subject: [Coral-List] Tunicate-killing coral spreading all across
> Caribbeanregion
> Dear Alex,
> The tunicate is Trididemnum solidum. This very effective coral killer
> has greatly increased in many locations all around the Caribbean, but
> much more in some places than others. I think the first description
> of it overgrowing coral was by Chuck Birkeland when he was a post-doc
> in Belize, and it was at that time a rare curiosity. 10 years ago
> when I told him it was no longer a novelty and had become a big
> problem, he was very  surprised. I began noticing it spreading in
> Jamaica around 1990. Rolf Bak began noticing its spread in Curacao
> and Edwin Hernandez Delgado in Puerto Rico about 10 years ago, around
> the time that I alerted Cozumel divers to it. I've seen quite a bit
> of it in St. Martin, the Grenadines, Tobago, Panama, Cozumel, Turks
> and Caicos, and Bonaire, where the worst infestations I have ever
> seen were at the very north end of the island, with around 40% of the
> coral surfaces overgrown.  In some places colonies are more whitish
> cream colored, or beige, but in some places they have distinct green
> or blue tints due to their symbiotic cyanobacteria. For example those
> in north eastern Jamaica are more blue.
> There is at least one similar didemnid in the Indo-Pacfic with a
> rubber mat like consistency. But the other Didemnids there look very
> different, and are not thick and rubbery but thin and brightly
> colored. Some are very common but do not overgrow corals, like
> Didemnum molle, which can be brown and white or green and white, but
> other species can grow so fast that they overgrow corals. After the
> 1998 high temperature mortality of corals in Indonesia, tunicates,
> not algae, overgrew the dead coral very quickly, to my surprise. In
> Sri Lanka in 1997 I found a green didemnid that grew so fast it was
> smothering macrophytic algae, especially Halimeda.
> As far as I have been able to find out from the tunicate specialists
> at the Smithsonian, there seems to be little or no work on what they
> actually eat, but they are presumed to eat the same sort of
> zooplankton as corals. That seems to me not be correct, because there
> has been a dramatic increase in their abundance and killing of
> corals, and it looks as though something they can eat better than
> corals can must be increasing. The fact that the highest abundances
> of T, solidum in Bonaire is in a protected area with uninhabited
> areas downstream with no human pollution at all implies this must be
> some sort of a natural trophic shift, perhaps related to changes in
> upwelling in the Cariaco Trench. For sure this pest is increasing all
> over the Caribbean, but at very different rates, and the different
> abundances may have some clue into changes in its food supply. What
> is driving it needs to be worked out, because a lot of coral is being
> killed by it. This would make a good topic for students!
> Hope to catch up with you in Cocle this year, on the way to Azuero!
> 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
>> Date: Wed, 16 Jan 2008 12:44:25 -0500
>> From: Alex Brylske <Brylske at aol.com>
>> Subject: [Coral-List] Fwd: Mat tunicate problem?
>> To: coral-list coral-list <coral-list at coral.aoml.noaa.gov>
>> Message-ID: <1302C019-EB0C-4D70-91E9-CACFEABC2D8A at aol.com>
>> Content-Type: text/plain;	charset=WINDOWS-1252;	format=flowed;
>> 	delsp=yes
>> Received this letter from a reader, and would appreciate some insight
>> from the group. Is he talking about some kind of colonial tunicate?
>> Sorry, he didn't send any images.
>> Alex
>> Alex Brylske, Senior Editor
>> DIVE TRAINING magazine
>> Address:
>> 4314 SW 18th Place
>> Cape Coral, FL 33914
>> Phone: 239-471-7824
>> Cell: 954-701-1966
>> Fax: 281-664-9497
>> E-mail: brylske at aol.com
>> Website: www.dtmag.com
>> Begin forwarded message:
>>> From: Roger Dunton <roger335 at comcast.net>
>>> Date: January 16, 2008 12:26:47 PM EST
>>> To: Alex Brylske <brylske at aol.com>
>>> Subject: Mat tunicate problem?
>>> Alex,
>>> While leading a group in Cozumel this Christmas, I met a lovely
>>> couple who pointed out what we believe may be a problem infestation
>>> of the coral reefs. I am including their description to see if you
>>> are aware of this and perhaps what might be done. They referred to
>>> it as a ?MAT TUNICATE?, but it was unlike any tunicates of which I
>>> am aware.
>>> ?First of all, we are not sure of the name, it was given to us by a
>>> dive master in Belize on Turneffe Island.  We have looked through
>>> the name on internet but did not find anything close to it.
>>> Whatever its name, this algae is light grey - a bit greenish, and
>>> when taken to surface it is actually a pale pink.  It is thick and
>>> feels rather soft to touch, like leather.  It covers the coral like
>>> a blanket.  Actually when you look close, it seems to start with a
>>> small drop, and you can see several drops like sprayed from above.
>>> Each drop seems to develop into a blanket that covers the whole
>>> coral head it started on, and grows along the stems of fans and
>>> sponges until it covers it entirely.
>>> The dive master in Belize indicated that the algae should be
>>> removed, or at least untucked from the coral head on the edges to
>>> stop its growth.  When you do this, it is sometimes easy and comes
>>> in large pieces, sometimes it breaks into small crumbs.  Below the
>>> blanket, the coral is dead, and it seems there is only rock.  There
>>> are often thin spiders with long legs or long worms between the rock
>>> and the algae.  The algae is soft when taken off the coral, and when
>>> it dries on the surface it becomes rigid.
>>> We have seen it a lot in Belize on the East side of Turneffe Island,
>>> and we start to see it a lot in Cozumel, at about any depth.  We
>>> have not been able to observe a pattern, but I thought there was
>>> maybe more of it in shallower waters.  The weird thing is that when
>>> you start looking for it, you see it a lot whereas if you are not
>>> looking, you don't notice it so much.
>>> I would be interested in learning what it is, and what should be
>>> done with it: remove it and dispose of it at surface, or just untuck
>>> it, or leave it alone?
>>> Thank you for any light you might shed on this.?
>>> -Roger Dunton
> 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
> _______________________________________________
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
> http://coral.aoml.noaa.gov/mailman/listinfo/coral-list

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

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