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

Thomas Goreau goreau at bestweb.net
Thu Jan 17 13:03:12 EST 2008

Dear Andrew,

Thanks,. I do recall a paper on Hawksbill sponge feeding preferences  
some time ago (and not just Xestospongia muta), but have lost track  
of the reference, and sponge and turtle people I ask don't seem to  
know about it. Anyone out there know?

You may remember that a couple of years ago somebody posted something  
on the list server about a dog in Jamaica being poisoned by a marine  
organism it chewed that was thrown up on the beach by a storm. They  
provided a photo, and everybody was sure it was Briareum asbestinum.  
I sent the photo to the top octocoral expert at the Smithsonian, my  
father's very old friend the late Ted Bayer, who insisted it was no  
gorgonian but a tunicate, and sent it to their tunicate lady (whose  
name I now forget) who said it was indeed a tunicate, and many of  
them were toxic as hell, repeating the old story about  whopping high  
vanadium content, which as far as I recall was a measurement from a  
single species.

But why is it outcompeting corals when it didn't in the past?

I'll be back to you when I can get to reading your files.......

Best wishes,

On Jan 17, 2008, at 9:58 AM, andrew ross wrote:

> I think of animals that eat distasteful poisonous
> things, such as turtles and larger angelfish, and i
> think of animals not present in the areas where this
> stuff is taking over around here (Dr's Cave)... such
> as turtles and large angelfish....
> There is a paper out there in the ether about turtle
> food choice in turtles and sponges, with
> less-tasty/more toxic sponges eaten only in high
> turtle populations, so higher competition. How bad
> does this tunicate taste?
> I also see this tunicate taking over in areas where
> bio-erosion, and in particular boring sponges are
> ridiculously common, making nursery coral out-planting
> a time consuming and destructive process (substrate
> crumbles with any pressure). They both appear to be
> being fed and not consumed.
> Ocean acidification will have nothing left to melt.
> A
> --- Thomas Goreau <goreau at bestweb.net> wrote:
>> 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,
>> Tom
>> 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
> === message truncated ===
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Thomas J. Goreau, PhD
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
goreau at bestweb.net

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