Diadema die off - another reference

Robert W. Buddemeier buddrw at ku.edu
Thu Jan 30 19:29:51 EST 2003

Interesting -- African dust doesn't sound like a very good vector for an

Two other observations on the Dust Discussion --

1.  Paleoclimate -- based on (dust-relevant) African contributions to
Atlantic sediments, the Sahara desertification was complete and its sediment
output quasi-steady-state by 5000 years BP.  (I think the reference is
deMenocal et al. 2000, Quat. Sci. Rev. 19:347-361) If dust were a reliable
vector there should have been plenty of chances for ecosystem inoculation
before the past decade; alternatively, if this (putative dust-borne
infection) were a statistically unique event in the Quaternary, then there
probably no way to 'prove' it, but probably also not much reason to worry
about it in the future.

2.  Experimental studies -- I think it would be extremely difficult to
any sort of mesocosm test of the dust hypothesis -- in addition to the issue
of how to test for or rule out statistically rare episodic inputs, there is
the serious experimental design problem inherent in the enormous differences
in surface/volume ratios between aquaria and the real ocean.

If you delivered a realistic oceanic surface dose (g/m2/day) to an aquarium,
the resultant water concentration would be orders of magnitude greater than
in a natural system, and if you tried to generate a realistic oceanic water
column concentration in an aquarium, you would be dealing with an almost
unmanageably small (and therefore probably unrepresentative) input dose.
Further, the high internal (solid) surface to (water) volume ratio of the
aquarium system, combined with low water motion relative to the real ocean,
would confound interpretation of the behavior of particulate contaminants.

Bob Buddemeier

Jim Bohnsack wrote:

> In the various discussions, I did not see the following reference
> mentioned concerning the cause of the Caribbean Diadema die off in 1983.
> Bauer, J.C. and C.J. Agerter.  1987.  Isolation of bacteria pathogenic
> for the sea urchin Diadema antillarum (Echinodermata: Echinoidea). Bull.
> Mar. Sci.  40(1): 161-165.
> It provides evidence that an anaerobic bacteria Clostridium was the
> responsible agent.  I believe this study was able to satisfy all but one
> of Koch's postulates.  The last one can not be tested because no known
> specimen that actually died in the kill was preserved by freezing.
> Also, I vaguely rember (i.e. I can not verify) someone mentioning that
> this kill occurred just after Panama started preventing ships from
> releasing ballast water and other discharges in the Panama Canal.
> Presumably, cruise ships that held sewage in tanks while crossing the
> Isthmus would have plenty of opportunity to build up anoxic conditions
> in their tanks and large abundance of Clostridium.  If there is any
> merit to this hypothesis, I hope everyone appreciates the irony of having
> one regulation designed to prevent environmental damage (i.e. protect
> water quality in the Panama Canal) causing great damage elsewhere.
> REF:
> > Date: Fri, 17 Jan 2003 10:08:33 -0500
> > From: Gene Shinn
> > Subject: Dust and other Hypotheses
> >
> > TimesDear Coral Listers,
> >
> >      Since there has been so much discussion of the African dust
> > hypothesis on the list in recent weeks, I could resist responding no
> > longer. First, the experiments proposed by Jim Hendee to test African
> > dust effects on corals are similar to ones I have been proposing for at
> > least 5 years. Unfortunately, there is little funding to do such work.
> > In addition, the USGS does not have in place the dust collectors you
> > mention. We sample for microbes using very small samples and collection
> > requires only 10-to-15 minutes. We do no routine monitoring but would
> > if we could. There is no funding for the large expensive samplers
> > needed to provide enough  sample for the experiments Jim proposed.
> > Secondly, the major problem with finding the Diadema pathogen is that
> > the pathogen that first killed them has not been identified so we do
> > not know what to look for. It would be possible, however, to test
> > living Diadema against those microbes that have been cultured from dust
> > thus far.
> >
> >      I thank Lessios for answering Alina's question regarding survival
> > of West African Diadema. I did not have an answer as elegant as his. I
> > could only suggest that Diadema living so close to the source, like the
> > humans and the Siderastera sp. that survive there, long ago adapted and
> > those that didn't died. Lessios also makes some very valid points
> > regarding water transport of the unknown pathogen. We accept that the
> > Diadema die-off began near the Panama Canal (Lessios et al., 1984,
> > Science, 226:335-337). We also point out that the die-off began in
> > winter when African dust impacts the southern Caribbean, South America
> > and the Panama region and it was also the dustiest year since Prospero
> > began monitoring dust in 1965. The upper Caribbean is impacted later
> > during the summer months. Like Lessios, we believe water transport is
> > very important. How else would it infect Diadema in aquaria (I assume
> > we are talking running seawater aquaria)? Once the Caribbean basin is
> > impacted as shown in the NOAA satellite image in our 4-page info sheet
> > in our website, water currents likely complete the distribution of any
> > pathogens delivered from the air. Areas downcurrent, such as, Belize
> > and Florida, were impacted by the disease after Panama. What has
> > concerned us, however, is how did the pathogen later move hundreds of
> > miles against the Caribbean Current to reach the Lesser Antilles? Dust
> > contamination of the Atlantic seaward of the Antilles and then
> > transport downcurrent to the Antilles seems a reasonable possibility.
> > There is nothing between the Antilles and Africa, and both the wind and
> > the currents move toward the Antilles. More recent studies conducted by
> > microbiologists at our office show that microbial species in dust can
> > change drastically within 30 minutes. Don't expect a dust cloud to
> > deliver the same microbes everywhere at the same time.
> >
> >     My main point is that the dust hypothesis is just that, an
> > hypothesis, as are the other proposed causes of Diadema and coral
> > death. The ballast-water origin is an unproven hypothesis, as are the
> > other "usual suspects" that drive coral research funding. This latter
> > point gets back to what Jim pointed out a week earlier regarding the
> > emotional "pollution" word. Where is the original basic research
> > demonstrating the degree of damage done to corals by the "usual
> > suspects," oil spills, sewage, sedimentation, and mosquito spraying, to
> > name a few? We seem to have skipped over the basics and then let
> > assumptions and emotion guide our research and funding agencies.
> >
> > Best Wishes, Gene
> >
> ~~~~~~~
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Dr. Robert W. Buddemeier
Kansas Geological Survey
University of Kansas
1930 Constant Avenue
Lawrence, KS 66047 USA
e-mail: buddrw at ku.edu
ph (1) (785) 864-2112
fax (1) (785) 864-5317

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