[Coral-List] Tunicate-killing coral spreading all across Caribbeanregion
Janie Wulff
wulff at bio.fsu.edu
Thu Jan 17 11:41:45 EST 2008
In a 1995 Marine Ecology paper (P.S.Z.N.I. Mar Ecol 16:145-163),
Brian Bingham and Craig Young remark that they observed the polyclad
flatworm Pseudoceros crozieri feeding on zooids of Ecteinascidia
turbinata colonies until only basal stolons remained.
-Janie Wulff
At 5:56 PM -0500 1/16/08, Thomas Goreau 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
>>>
>>> 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
>President
>Global Coral Reef Alliance
>37 Pleasant Street, Cambridge MA 02139
>617-864-4226
>goreau at bestweb.net
>http://www.globalcoral.org
>
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