[Coral-List] Palythoa overgrowing corals in Trinidad and elsewhere

Thomas Goreau goreau at bestweb.net
Mon Mar 10 13:46:22 EDT 2008

Palythoa overgrowth of corals is being studied in Toco and Salybia,  
Trinidad, by a research group at the University of the West Indies at  
St. Augustine including Dawn Philip, Jennnie Mallela, Lee Ann Beddoe,  
and Stanton Belford. Our observations, compared to earlier work by  
other Trinidadian researchers, shows that Palythoa is clearly  
overgrowing corals and expanding over the reef flat.

We see the same thing happening on a large scale in Broward County  
Florida, where Dan Clark and I just photographed this last week, and  
where large old corals are being overgrown. The same Palythoa  
dominance is common in southern Brazil, for example from Cabo Frio  
and Arraial do Cabo southwestwards. Palythoa mats dominate large  
areas of the reefs of Cabo Verde, and photos sent to me last week by  
Joao Gama Monteiro show it is even overgrowing Millepora there.

Palythoa is a pest in that it is toxic so it provides neither food  
nor shelter, and it's spread at the expense of corals in many places  
is a serious concern, but the ecological factors allowing it to  
spread are not known. One possibility is that food supplies that  
Palythoa is a more effective consumer of than corals are increasing,  
but little is known of the feeding habits of Palythoa, according   
James Reimer, a zoanthid expert I specifically asked about this a few  
years ago.

Trinidad is an interesting exception to the general rule in that the  
other places where Palythoa is dominant are near the extreme cold  
limit of corals, which Trinidad is not, however it is near the  
extreme sedimentation limit of corals due to the influence of the  
Orinoco River.

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

Message: 5
Date: Fri, 7 Mar 2008 16:44:43 -0400
From: "Jan-Willem van Bochove" <jvb at coralcayconservation.com>
Subject: [Coral-List] Zoanthid (Paltythoa caribaeorum) overgrowth of
To: <coral-list at coral.aoml.noaa.gov>
Message-ID: <20080307205035.40516179F5 at coral.aoml.noaa.gov>
Content-Type: text/plain;	charset="us-ascii"


I've noticed that P. caribaeorum, a colonial zoanthid which forms  
mats, is overtopping and smothering a large variety of scleractinian  
in shallow reef environments in Tobago.

P. caribaeorum is an aggressive, fast growing and toxic zoanthid  
which seems
to stop at nothing and I have yet to see any significant predation on  
species. In a small, sheltered bay where most of our observations  
were made,
it forms the dominant substrate with over 75% cover in the shallows  
We have also seen it overtopping massive corals in deeper waters.

I was wondering if anyone has or knows of any recent research done on  
zoanthid or has noticed its abundance elsewhere on such a scale.  
Other than
a paper presented at the ICRS of 1981 in Manila by Suchanek and Green, I
have not come across any literature dealing with inter-specific  
with corals.

Images of the zoanthid overgrowing corals can be found on -


Any feedback is appreciated.



Reference -

Suchanek T.H., and Green, D.J., 1981. Interspecific Competition Between
Palythoa Caribaeorum and Other Sessile Invertebrates on St.Croix  
Reefs, U.S.
Virgin Islands. Proceedings of the Fourth International Coral Reef
Symposium, Manila, Vol. 2.

Jan-Willem van Bochove MSc
Chief Technical Advisor

Coral Cay Conservation Ltd
Elizabeth House, 39 York Road, London, SE1 7NJ, United Kingdom
Tel: +44 (0)20 7620 1411 (switch board)
Fax: +44 (0)20 7921 0469
email: jvb at coralcayconservation.com
skype: jhvanbochove

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