[Coral-List] How long can corals survive without theirsymbiotic zooxanthellae?

[Julian Sprung]

I think it is important when answering this question, as Josh did, to point out the cause of the loss of zooxanthellae. Since high temp was the stimulus in the experiment with P. damicornis, and it is known that at elevated temp P. damicornis may die rapidly as a reult of a Vibrio infection, then the cause of death cannot specifically be blamed on lack of symbionts unless Vibrio had been ruled out.

I have seen bleached shaded colonies of P. damicornis in aquaria survive great lengths of time with few if any zoox's. The same is true for shaded portions of colonies that have zoox's in the upper illuminated branches, but that probably doesn't count.

My opinion on the question posed- while it may vary among species or genera, and there may well be exceptions, I believe that with sufficient food most corals can survive many months or indefinitely without symbionts. This can be demonstrated in temperature controlled flow through aquariums with no illumination and high food inputs (the water flushing removes waste and maintains water chemistry). 

While I cannot comment on the effects on growth, the survival is the question posed.

Sincerely,

Julian


-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov on behalf of Joshua Feingold
Sent: Sat 1/8/2005 10:31 AM
To: John P Carlin; coral-list at coral.aoml.noaa.gov
Subject: Re: [Coral-List] How long can corals survive without theirsymbiotic zooxanthellae?
 
Hi John,

I did some work on this for my dissertation, and survival is variable 
depending on the species and type of stress. Also, it is important to 
understand that, nearly invariably, bleached corals possess at least some 
zooxanthellae. The population size isn't enough to see pigment in the coral 
with the naked eye, but they are there in the tissues, but at very low levels.

One species I investigated, the fungiid Diaseris distorta, could remain 
alive in the bleached state for over 2 months and then regain pigmentation. 
In contrast, another species, Pocillopora damicornis, was much more 
sensitive with mortality occurring in nearly all colonies after 2-3 weeks 
in the bleached state. Elevated temperature was the stress in both of these 
examples.

Cheers,

Joshua Feingold
Nova Southeastern University Oceanographic Center

At 03:48 PM 1/7/2005 +0000, John P Carlin wrote:
>Hi,
>
>I would like to know if there has been any published work on how long corals
>can survive without their zooxanthellae following a stress event?
>
>Thank you
>
>John Carlin
>Reading University
>England
>
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