[Coral-List] Interesting paper
James Cervino PhD.
jcervino at whoi.edu
Tue Jan 22 09:07:33 EST 2008
Coral thermal bleaching vs vibrionic pailing
I agree with this informative clearly needed paper in theory outside of the FISH
tech used. I guess this comes down to "who came first the chicken or the egg"
Mechanistically speaking; as soon as the temperature is elevated in artificial
sea water, or natural tropical seawater, the zooxanthellae begin to divide
faster thereby over crowding the host animals stomach (gastroderm). In early
stages of thermal stress the zoox begin to become expelled out of the
gastroderm ie. bleaching! Len Muscatine et al. and Nora Goreau have observed
and shown this time and time again and their is good compelling histological
evidence that can show this physiological mechanism.
The vibrios are not inducing this physiological mechanism towards the coral
animal and its symbioant. The vibrionic "mass bleaching theory" is not
responsible for what happened during 1982-83, 1986-87, 1993-95 and again in
1998-99. During these hot-spot events (Goreau & Hayes 1994 AMBIO & Goreau et
al, 2000 Conservation Biology) one can see the surface waters in tropical reef
habitats floating with symbiotic zooxanthellae. On a research cruse in PNG
during late 1998 there were areas approx.170 miles from any visible coastline
where I was able to see algal/zoox floc trails covering the surface waters at
all the dive sites. When diving, one can visually see zoox extruding out of the
oral cavity in all thermally bleached specimens. When analyzing diseased
specimens one does not see this, as there is an in-hospite destruction of the
zoox as shown in Vibrionic infection and their are good histological
differences that show this (Cervino et al., 2004 Symbiosis; Keshavmurthy et
Thermal stress is the primary abiotic stress factor; it simply happens first and
is responsible for the mass mortalities we are seeing. Secondary Vibrionic
infection plays a completely different role due to an infection as the result
of over colonization of these Vibrios that are taking advantage of a carbon
rich mucus substrate with an entirely different chemical composition that
influences microbial shifting populations (Ritchie 2007) .
Therefore I agree with this new paper and remain un-convienced of the bacterial
bleaching hypothesis in that bacterial bleaching is responsible for mass coral
reef bleaching. Although FISH techniques may not be a good measure for
identifying Vibrio populations future research should include PCR-DNA
sequencing of the populations before-during and after thermal stress. Also, one
can simply measure the cell cycle MI% differences and compare the differences
between thermal stress vs infection, coupled with TEM and histo-techniques.
A paper by White Syndrome by G. Roff et al., 2007 Coral Reefs outlines a nice
clear physiological description of "the pathology of a coral tissue disease"
Dr. James M. Cervino
Pace University & Visiting Scientist
Woods Hole Oceanographic Inst.
Department of Marine Chemistry
Woods Hole MA.
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