[Coral-List] Eradicating Trididemnum solidum

Jessica Craft Jcraft at coastalplanning.net
Thu Jan 17 08:32:02 EST 2008


I don't know the literature on T. solidum, but for a rapidly expanding
mat tunicate, known as Didemnum sp. in more northern waters, pulling the
mats off is not recommended as this highly invasive species spreads
rapidly and broken fragments can wedge themselves into the hardbottom
and spread new colonies.  This particular species is running rampant all
over the globe now: along the northeast and northwest coasts of the
U.S., Europe, New Zealand and Japan.  It is now covering a large expanse
of the Georges Bank. Recently we've observed it beginning to spread off
the east coast of Nantucket. Perhaps invasive and nuisance mat tunicates
are the new threat to coral and hardbottom communities? Add them to the


Bullard, S. G., Lambert, G., Carman, M. R., Byrnes, J., Whitlatch, R.
B., Ruiz, G., Miller, R. J., Harris, L., Valentine, P. C., Collie, J.
S., Pederson, J., McNaught, D. C., Cohen, A. N., Asch, R. G., Dijkstra,
J. and Heinonen, K. 2007. The colonial ascidian Didemnum sp. A: current
distribution, basic biology, and potential threat to marine communities
of the northeast and west coasts of North America. J. Exp. Mar. Biol.
Ecol. 342: 99-108.

Valentine, P. C., Collie, J. S., Reid, R. N., Asch, R. G., Guida, V. G.
and Blackwood, D. S. 2007. The occurrence of the colonial ascidian
Didemnum sp. on Georges Bank gravel habitat - Ecological observations
and potential effects on groundfish and scallop fisheries. J. Exp. Mar.
Biol. Ecol. 342: 179-181

Bullard,SG, Sedlack, B, Reinhardt, JF, Litty, C, Gareau, K, Whitlatch,
RB. 2007. Fragmentation of colonial ascidians: Differences in
reattachment capability among species. J. Exp. Mar. Biol. Ecol. 342:

Jessica A. Craft
Marine Biologist
Coastal Planning & Engineering, Inc.
Marine Science & Biological Research 
2481 NW Boca Raton Blvd.
Boca Raton, FL 33431
Ph 561-391-8102
Fax 561-391-9116
><))>o              o

-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov
[mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Thomas
Sent: Wednesday, January 16, 2008 4:51 PM
To: coral-list coral-list
Cc: Roger Dunton
Subject: [Coral-List] Eradicating Trididemnum solidum

Sorry to pile on, but I did not answer Roger Dunton's key question:  
what to do?

I always pull off all I can, because this is real pest, and it is  
killing huge amounts of coral. You feel good to save a bit of coral,  
but it is almost hopeless because there is so much of it.  So you can  
wind up not seeing anything else and using up all your air.

They klll coral by smothering, not by biological predation or  
chemical toxicity, there is no reaction by the coral to the  
encroaching threat. Nothing seems to eat it, but Roger Dunton's  
observations of the worms are really fascinating.

We really don't know why this has become such a plague in places  
where it did not used to be. It used to be very very rare in Jamaica  
for many decades and suddenly began to spread and spread. Because  
tunicates are thought to rely on the same resources as corals,  
zooplankton and photosynthetic symbionts, it is a little hard to know  
why they are taking over so much, and my guess is it must be a  
trophic shift of a subtle kind, I suspect related to changes in the  
ocean plankton food chain that are pervasive, but not the same  

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

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;

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 Brylske, Senior Editor

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
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