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

William Allison allison.billiam at gmail.com
Sat Jan 19 08:36:45 EST 2008


Re eaters of tunicates:

Leon & Bjorndal (MEPS;245;249) in a challenge to a speculation that
hawksbills may be exclusively spongivores (e.g., Meylan:
Science;239;393) report hawksbill feeding on sponges and false coral.
Perhaps van Dam & Diez (8th ICRS;1421) say something about tunicate
consumption.
I have seen hawksbills searching for and eating both sponges and false
corals but not tunicates, but some asteroids eat all three and more.

I have documented Tunicate consumption by the cushion star Culcita
which like a number of other Indian Ocean Asteroids, also consumes
encrusting sponges. Culcita also eats small corals but has had no
discernable effect on the coral communities I am studying specifically
to detect the general effect of this predation. To the contrary, I
suspect their catholic tastes open space for coral settlement,
especially when coral cover is low. Killing such asteroids because
they eat small corals, as some misguided white knights are doing in
Maldives, may be a mistake for this reason. As a general principle, it
is arguably a mistake when their role in the system is not understood.

Bill


On Jan 17, 2008 1:03 PM, Thomas Goreau <goreau at bestweb.net> wrote:
> 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,
> Tom
>
> 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
> 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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