[Coral-List] Question concerning cold temps and coral stress.

James M. Cervino cnidaria at earthlink.net
Wed Dec 7 08:31:25 EST 2005

Dear Melissa,         

With regards to the differences between cold water coral bleaching 
and thermal (expulsion) bleaching; yes they do loose their symbiotic 
algae as a result of cold water stress. I have seen this in PNG along 
a coral wall where deep water was being up-welling  cool water 
vertically for a week. The extreme cool water was brought to about 65 
feet. At that point the temperatures increased and mixed with the 
warmer surface water that was between 87-88F. We monitored the 70-65 
feet depth range and watched the corals for that week as they were 
getting the continual supply of cool 69-70F water. We noticed the 
Pachyseris sp. (Tabular plate coral 12 feet wide) begin to bleach. 
The algal mass was clustered around the oral disk well below the 
tentacals and seemed to remain there for a few days. Eventually this 
mass is slowly pushed out due to the cold shock. Where as, during 
thermal expulsion the algal (zooxanthellar) mass is pushed out much 
faster into the water column due to newer algae (zoox) continually 
dividing within the gastroderm.  This creates an over crowding 
population of algae within the host and disrupts the steady state 
symbiotic association between host animal and its resident symbioant. 
The alga/zooxanthellae become forced out of the gastrodermal cavity 
into the colenteron and then into the water column, hence "bleaching 
the coral".

I also conducted  this work in vitro with Len Muscatine during 1995 
and then again during 2000 with Garriet Smith (with pathogens and 
cool water trials).  During the in vitro experiments we noticed that 
the initial cold shock triggers the initial increase in division of 
the algae and then sort of slows down compared to thermal shock where 
division is constant until all the algae/zoox are vacant from the 
gastroderm. Hence much more algal pellets were being expelled during 
thermal shock compared to cold shock.  Recovery was faster during 
cold shock whereas during thermal stress 75% our testing corals died 
and did not recover. All cold water treatments survived.  Below are 
my references. The observations in PNG were also positive whereas the 
colonies of Pachyseris survived and fully recovered.  Can anyone on 
the list share similar observations in vitro and in situ?


Steen, R.G., and L. Muscatine. 1987. Low temperature evokes rapid 
exocytosis of symbiotic algae by a sea anemone. Biol. Bull. 

Gates RD, Baghdasarian G, Muscatine L (1992) Temperature stress 
causes host cell detachment in symbiotic cnidarians: implications for 
coral bleaching. Biol Bull Mar Biol Lab Woods Hole 182:324-332

Hoegh-Guldberg O, McCloskey LR, Muscatine L (1987) Expulsion of 
zooxanthellae by symbiotic cnidarians from the Red Sea. Coral Reefs 

Hoegh-Guldberg O, Smith GJ (1989) Influence of the population density 
of zooxanthellae and supply of ammonium on the biomass and metabolic 
characteristics of the reef corals Seriatopora hystrix and Stylophora 
pistillata. Mar Ecol Prog Ser 57:173-186

Muscatine L, Pool RR (1979) Regulation of numbers of intracellular 
algae. Proc R Soc Lond B 204:131-139

Titlyanov EA, Titlyanova TV, Leletkin VA, Tsukahara J, Van Woesik R, 
Yamazato K (1996) Degradation of zooxanthellae and regulation of 
their density in hermatypic corals. Mar Ecol Prog Ser 139:167-178

Trench RK (1979) The cell biology of plant-animal symbiosis. Ann Rev 
Pl Physiol 30:485-532

>If we have a much colder than usual winter  here in the Caribbean, 
>how might the corals be affected?  Do they  stress and perhaps die 
>as a result?  Do they lose their  Zooxanthellae as with excessive 
>heat?  Which corals are more  sensitive to cold?
>   Thanks in advance for any replies,
>   Melissa Keyes
>   independant coral reef monitoring project
>   St. Croix, USVI
>Yahoo! Shopping
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Dr. James M. Cervino, MS, Ph.D.
Marine Pathology
Department of Biological & Health Sciences
Pace University New York NYC
Phone: (917) 620-5287
Web site: http://www.globalcoral.org

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