[Coral-List] bacteria reservoirs and coral disease

[Thomas Goreau]

Dear Andrew,

Your observations are very interesting, and I am sure there is  
something to them. But to do more you will need to compile 16S rRNA  
libraries of the bacterial populations on corals and nearby waters,  
rocks, and sediments , and and I know only too well that back home in  
Jamaica we don't have the resources to pay for such work! What is  
worse is that the funding agencies in the rich countries have  
repeatedly dropped the ball on good field work to identify pathogens  
and understand how and where these bacteria spread from, so very  
little information is available, although Rohwer and Fouke and their  
colleagues and others are doing great work on this.

In my view disease results from proliferation of parasites, and has  
little to do with coral health per se or pollution in most cases  
(Bruce Fouke's group's work on BBD bacteria in Curacao and Serratia  
marecescens in White Pox being the exceptions), because if they were  
correlated we would see much more disease concentrated in polluted and  
stressed areas than we do. In the Turks and Caicos there was no  
association of coral diseases with any obvious stress or pollution  
factors, but there WERE associations with specific algae. So the key  
is to understand where the bacteria come from and how they move.

As mentioned in another post, we found strong statistical evidence  
from large scale distribution patterns of association between White  
Plague, Black Band, and Gorgonian Disease and various algae in the  
Turks and Caicos. That was not based on small scale experiments like  
Vu et al., Smith et al., and Nugues et al., which is the obvious next  
step to test if there is an association, followed by microbiology. We  
did not see such patterns in YBD, but it was too rare there to  
tabulate. We did see Pseudo-White Band on palmata and cervicornis, but  
I lumped it with WP because they all showed very wide white bands,  
5-10 cm across, characteristic of WP, but not the few millimeter-wide  
to centimeter bands typical of classic WBD.

Of all the coral diseases, the only one whose pathogens are clearly  
known is YBD, thanks to James Cervino's work, and White Pox, thanks to  
Katie Patterson. No one has ever convincingly found the pathogen for  
WBD to my knowledge, despite some early claims in that direction  
(Garriett Smith and Kim Ritchie thought a Vibrio might be involved).  
The cyanobacteria in BBD was shown very early on by Antonius and  
Rutzler (and later validated by Richardson and colleagues) NOT to be a  
pathogen per se, and the coral death resulted from sulfide production  
by bacteria at night in the reduced oxygen diffusion matrix created by  
cyanobacteria, rather than a pathogenic disease per se. Claims that  
Aurantimonas is the cause of WP are now known to be wrong, and it is  
likely only to be an occasional secondary opportunist, with the  
primary pathogen unknown. Hopefully this situation will change soon,  
and perhaps our colleagues can update this brief summary.

Best wishes,
Tom


On Feb 26, 2009, at 3:12 PM, Andrew Ross wrote:

> Dr. Goreau,
> After one of the hurricane wave-sets this summer i had several  
> mature nursery-growing A. cervicornis develop WBD resulting in  
> partial or total death. Diseased samples were not necessarily  
> adjacent in the nursery or able to touch.
> Infection occurred on suspended line nurseries .8 and 1.5M from the  
> sand on propagated corals that had no physical damage/disease entry  
> points. No (particular) abrasion, no predation/vectors.
> The rock 4m away has some sort of endemic WBD as all samples planted  
> to it die of WBD symptoms. No A. cerv occurs on this rock naturally,  
> though there is (old) rubble. This rock is a set-point for jack- 
> season (summertime) fish-pots (not sure if this is important, but  
> thought i'd mention). The main reef 7m seaward/the other direction  
> has some living A. cervicornis without disease.
>
> The site is the Widowmaker Cave dive site off the MoBay airport. You  
> may know the spot. I've been growing coral on lines here for 3 years  
> and have only seen WBD in the nursery on this occasion.
>
> The illness/pathogen seems to be in the sand or in the sediments of  
> that rock. The nursery corals were infected when the storm brought  
> up/over the pathogen.
>
> Thanks for the paper. i've enjoyed all the discussion this week and  
> the papers mentioned have been very useful.
>
> Andrew
>
>
> --- On Wed, 2/25/09, Thomas Goreau <goreau at bestweb.net> wrote:
>
> > From: Thomas Goreau <goreau at bestweb.net>
> > Subject: [Coral-List] bacteria, nutrients, diffusion, turbulence
> > To: coral-list at coral.aoml.noaa.gov
> > Date: Wednesday, February 25, 2009, 8:05 PM
> > >
> > Forest Rohwer raises some very important points below, but
> > it is
> > important to consider BOTH molecular and turbulent
> > diffusion in such
> > arguments, and his comments are strictly correct only for
> > the former.
> >
> > Real world nutrient and bacterial interactions are going to
> > involve a
> > mixture of molecular diffusion in totally static zones and
> > on
> > surfaces, laminar diffusion in surface boundary layers
> > (typically
> > millimeters/centimeters), and fully turbulent diffusion on
> > a larger
> > scales (millimeters/centimeters on up). So while I agree
> > with many of
> > Rohwer's points about the importance of experimenting
> > on a range of
> > scales, there are still mechanisms to transport bacteria,
> > toxins, and
> > allelochemicals over the distances in Vu et al's
> > experiments.
> >
> > This is reminiscent of a huge oceanographic controversy in
> > the early
> > 1970s in which phytoplankton were found to enormously
> > increase their
> > nutrient uptake rates at high concentrations (just like
> > reef algae
> > do). Some argued that phytoplankton took up the vast bulk
> > of their
> > nutrients when they happen to drift through clouds of fresh
> >
> > zooplankton pee/poo (hope that word passes the politically
> > correct
> > standard keepers!). McCarthy got tenure at Harvard by
> > making
> > calculations of the rate of diffusion of nutrients from
> > pee/poo
> > clouds, and concluded that he had turned ocean ecology on
> > its, well,
> > rear. But he used molecular diffusion coefficients
> > appropriate to
> > totally still fluids. In fact the turbulent eddy diffusion
> >
> > coefficients of the real world ocean are a million to a
> > hundred
> > million times higher! This means that these drifting clouds
> > of high N
> > and high P would be diffused away before phytoplankton or
> > bacteria
> > could get to them, unless they lived right ON the source,
> > with lips
> > closely appressed, passively mobile bottom-feeders, so to
> > speak.
> >
> > There has been inadequate consideration of the importance
> > of
> > turbulence in coral reef ecology, but in fact this is a
> > crucial
> > transport mechanism even on very small scales. The reason
> > that it has
> > been ignored is because turbulent eddies could not easily
> > be
> > visualized. That limitation has now been removed, and we
> > are now able
> > to image turbulence in real time on scales down to
> > microscopic. In a
> > recent paper several mathematicians at MIT and I have
> > redeveloped my
> > grandfather's method of visualizing turbulence in real
> > time, which had
> > not been used for 70 years. This allows the full details of
> > turbulent
> > transport to be visualized directly in real time in the
> > laboratory. A
> > vast wealth of new information on the role of physics in
> > biology at
> > small and intermediate scales will follow its serious
> > application. See:
> >
> > http://www.globalcoral.org/TMV.pdf
> >
> > Thomas J. Goreau, PhD
> > President, Global Coral Reef Alliance
> > Coordinator, United Nations Commission on Sustainable
> > Development
> > Partnership in New Technologies for Small Island Developing
> > States
> > 37 Pleasant Street, Cambridge MA 02139
> > 617-864-4226
> > goreau at bestweb.net
> > http://www.globalcoral.org
> >
> > > Date: Tue, 24 Feb 2009 09:03:36 -0800
> > > From: Forest Rohwer <frohwer at gmail.com>
> > > Subject: [Coral-List] Algae, DOC, microbes and corals
> > > To: Coral-List at coral.aoml.noaa.gov
> > > Message-ID:
> > >
> > 	<3decc8d00902240903y2beada31k8c4f371f319d47da at mail.gmail.com>
> > > Content-Type: text/plain; charset=ISO-8859-1
> > >
> > > The recent paper by Vu et al completely misses the
> > scale at which
> > > algae-DOC-microbe-coral dynamics work. Basically, the
> > authors put
> > > algae in
> > > bags and tacked them to corals. Then they expected the
> > DOC to diffuse
> > > several centimeters to the corals. In the real world,
> > diffusion only
> > > works
> > > over very small distances. Other factors like mass
> > transport rapidly
> > > destroy
> > > any diffusional signal. In fact, Vu et al show that
> > the DOC
> > > enrichment does
> > > not occur at distances >3 cms from the algae.
> > >
> > > The dynamics that need to be investigated at occur in
> > the micron-
> > > millimeter
> > > range. If you look at Figure 1 in the Vu et al. paper,
> > you can
> > > clearly see
> > > the real/important coral-algal interface is the one
> > that occurs
> > > against the
> > > coral (i.e., the bright green line in the photo; not
> > the algae in
> > > the bag
> > > several cm away). Even the reference nails for the
> > disease boundary
> > > are
> > > covered with algae as the coral-algal interface
> > advances. The algae
> > > in the
> > > bag about 3 cms away should not have any influence,
> > which is what the
> > > authors found. In fact, the Vu et al. data more
> > closely matches the
> > > proposed
> > > feedback between algae-DOC-microbe-coral (Smith et al.
> > 2006. Ecology
> > > Letter), then their own conclusions.
> > >
> > > Similarly, the authors should not expect the
> > algal-associated
> > > pathogens (as
> > > described in a very nice paper by Nugues et al.) to
> > easily "hop"
> > > from the
> > > bagged algae. From a microbial point-of-view, 3 cm
> > represents about
> > > 6,000
> > > body lengths. That would be like a human hopping 10
> > kms.
> > >
> > > There are a couple leasons here: First, think small
> > when you are
> > > dealing
> > > with microbes. If you look at coral-algal interfaces
> > use micro-
> > > probes and
> > > microscopes, then you see that most of the activity
> > occurs within
> > > very small
> > > distances. Second, don't title papers with a
> > conclusion that can
> > > easily be
> > > wrong. Many (most?) people aren't going to read
> > the details in the
> > > Discussion.
> > >
> >
> >
> >
> > _______________________________________________
> > Coral-List mailing list
> > Coral-List at coral.aoml.noaa.gov
> > http://coral.aoml.noaa.gov/mailman/listinfo/coral-list

Thomas J. Goreau, PhD
President, Global Coral Reef Alliance
Coordinator, United Nations Commission on Sustainable Development  
Partnership in New Technologies for Small Island Developing States
37 Pleasant Street, Cambridge MA 02139
617-864-4226
goreau at bestweb.net
http://www.globalcoral.org