[Coral-List] Survival of corals without zooxanthellae

RichardPDunne at aol.com RichardPDunne at aol.com
Sun Jan 9 17:28:00 EST 2005

You will find some useful information on this in:
C M Yonge 1931 The effect of starvation in light and in darkness on the  
relationship between corals and zooxanthellae. Scientific Reports of the Great  
Barrier Reef Expedition 1928-29. Vol I no 7. Corals kept in the dark but fed  
lost a high percentage of their zooxanthellae (colourless to the eye) but  
survived until the end of the experiment ( 228 days). Variable according to  
See also:
C M Yonge and A G Nicholls 1931 The structure, distribution and physiology  
of the zooxanthellae. Scentific Reports of the Great Barrier Reef Expedition  
1928-29. Vol I no 6. They constructed a light tight box on the reef flat 
through  which the seawater could flow. after 152 days many of the species contained 
very  few zooxanthellae but were otherwise in good condition. Their 
conclusion in this  respect was "without any doubt that individual reef-building corals 
at any rate  can flourish without contained zooxanthellae."
I doubt however that corals ever loose ALL their zooxanthellae - the best  
that Yonge noted was "almost completely absent". And in our own work even a  
reduction of 86% of the seasonal maximum density following severe bleaching  can 
leave 0.026 x 10^7 algae per sq cm of tissue area (260,000). (Brown et  al 
1999 MEPS 191:53-69).  
The evidence seems to point to an ability to survive without zooxanthellae  
if a source of food is available, and presuming the stress which caused the  
zooxanthellae loss does not persist or at least does not have a directly  
deleterious effect on the coral host itself.
Richard Dunne

Tel: 01833  650059

RichardPDunne at aol.com

More information about the Coral-List mailing list