[Coral-List] Excess algal symbionts increase coral susceptibility to bleaching

[Dale W Griffin]

A bit more dust trivia....I wouldn't dismiss the role that dust plays in
the Pacific....a recent publication by a research team estimated that ~60
million tons is Asian desert dust is deposited in N. America each year and
a number of years ago it was reported that Asian dust deposition onto the
N. Hawaiian Islands contributes to sustaining regional forests...and it is
not unusual for dust storms move east out of Australia

Sent from my iPhone

On Nov 20, 2012, at 12:10, "Christina Kellogg" <ckellogg at usgs.gov> wrote:

> *Yes, African dust has been falling the Caribbean for a long time.
>
> *But only in recent decades would that dust contain a mixture of chemical
> nasties (technical term) from the burning of plastic trash, tires, etc.,
> plus an increased microbial load from population centers with sewage
> problems.
>
> *I.e., not just about quantity, but also quality.
>
> *Not to say that dust alone is the cause of everything, but shouldn't be
> discounted as a compounding factor on top of our other favorite
> environmental insults.
>
> Best,
> Chris
>
>
> On 11/19/12 6:55 PM, "Douglas Fenner" <douglasfennertassi at gmail.com>
wrote:
>
> > *The spatial pattern of bleaching does not correspond well with the
pattern
> > of dust.
> > *African dust fell in the Caribbean long before reefs there started to
> > decline.
> >
> > Although the Caribbean receives significant inputs of African Dust, the
> > Pacific does not.  There was significant bleaching in the Pacific in
1998
> > in several places, I know that Palau was hit fairly hard.  The worst
> > bleaching in 1998 was in the Indian Ocean.  The northern Indian Ocean
does
> > get desert dust at times, as shown in the map that Gene pointed to (a
> > fabulous map which someone else told me about and I passed on).  But
the
> > map does not show dust over most of the Indian Ocean, and there was
massive
> > bleaching south of the dust area.  Thus, the pattern of bleaching in
1998
> > does not closely match that of the dust.  The main caveat to that is
that I
> > don't know when the data for the map was taken.  It looks to me like a
> > snapshot, since it shows individual storms.  But I don't know when it
was
> > based on, and with time these things can change greatly (though the
pattern
> > is likely to change relatively little).  The main desert areas are
north of
> > the Indian Ocean, so it doesn't make sense that the middle and southern
> > Indian Ocean would get dust.  But the Pacific Ocean can have bleaching
in
> > spite of very little dust.  Here in American Samoa, the NOAA weather
> > station on the windward side of the island measures some of the purest
air
> > anywhere on earth, since there are many thousands of miles of ocean in
all
> > directions, particularly east of us where the air usually comes from.
And
> > yet bleaching events have occurred here.  Mass bleaching corresponds
most
> > closely with temperatures, and bleaching events can be predicted quite
well
> > based on temperatures alone, including in areas without any dust.
Other
> > variables can have effects as well, for example the first mass
bleaching
> > event reported was from fresh water, if I remember (in Jamaica reported
by
> > Tom Goreau senior).
> >      Isn't it the case that African dust has been falling in the
Caribbean
> > for a very long time, at least 10's of thousands of years?   I believe
> > there are layers of it in places like the Bahamas that are very old,
> > deposited long before the current decline of the coral reefs began.
> >     Cheers,  Doug
> >
> >
> >
> > On Fri, Nov 16, 2012 at 11:34 AM, Eugene Shinn
<eshinn at marine.usf.edu>wrote:
> >
> >> Andrew, This is very interesting information especially because
> >> you're findings relate the combined effects of temperature, oxygen,
> >> and nutrients to bleaching.  We certainly have all three, including
> >> anthropogenic nutrient sources, in Florida but I keep remembering the
> >> sudden die-off of Acroporids at San Salvador in 1983. That was a time
> >> when there were few anthropogenic sources on that sparsely populated
> >> island surrounded by deep oceanic water. John Martins original
> >> discovery that iron was necessary for algal growth has been re
> >> confirmed by many experiments since then. Because 1983 and 1984 were
> >> peak years for African dust flux to the Caribbean I continue to
> >> wonder if it contained sufficient iron (also phosphate) to provide
> >> this necessary micro nutrient? It is certainly the source of the red
> >> soil on that otherwise limestone island. Could the 5-6 percent iron
> >> contained in African dust be sufficient to cause overstimulation of
> >> both cyanobacteria and dynoflagelate zooxanthellae and thus cause
> >> their expulsion i.e. bleaching?
> >>        Considering the co incidence of bleaching events with years of
> >> increased dust flux and warm quiescent summers makes one wonder. The
> >> year 1998 was especially warm and dust flux as measured at Barbados
> >> by Joe Prospero was almost as high as it was in 1983 and 1984. With
> >> such obvious correlations one would think that some curious coral
> >> biologist would have performed dosing experiments to validate or
> >> discard the dust hypothesis. Gene  PS: here is a great image of the
> >> dust belt provided by Douglas Fenner.
> >> <http://www.nasa.gov/multimedia/imagegallery/image_feature_2393.html>
> >>
> >> --
> >>
> >>
> >> No Rocks, No Water, No Ecosystem (EAS)
> >> ------------------------------------
-----------------------------------
> >> E. A. Shinn, Courtesy Professor
> >> University of South Florida
> >> College of Marine Science Room 221A
> >> 140 Seventh Avenue South
> >> St. Petersburg, FL 33701
> >> <eshinn at marine.usf.edu>
> >> Tel 727 553-1158----------------------------------
> >> -----------------------------------
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>
>
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