[Coral-List] Lionfish and African Dust

Mon Feb 10 20:25:18 EST 2014

Gene,
     The fact that fungus in the genus Aspergillus is in the African dust
makes it plausible that the dust might be the source of the sea fan
infections, since Aspergillus sydowii has been shown to be the cause of sea
fan infections (but see the quote near the end of this message).  Of
course, the Aspergillus  sydowii might have come from elsewhere.  For
Diadema, however, it doesn't fit the pattern at all, as I documented in my
previous message.  The gradual increase of white band disease on Acropora
doesn't fit with your proposition that it's "demise" occurred in 1983,
which seems to be based on your knowledge that Acropora was hit hard in a
couple places in 1983, and African dust had a peak in 1983.  That is a
coincidence, but Acropora died from white band in other parts of the
Caribbean in other years, and had started before 1983.  Of course African
dust has been going on for a long time, and it makes sense that it now
carries things that it did not before, including toxic chemicals and
microbes.  That doesn't prove that it caused either the Diadema disease or
the Acropora white band disease, and in fact is consistent with the strong
evidence from the temporal pattern that Diadema spread from one original
start in Panama, and didn't arrive on African dust, which would cover most
of the Caribbean simultaneously, and which disconfirms your African dust
hypothesis for Diadema disease source.
     Saying that African dust doesn't cause those, isn't the same as saying
it is harmless or does nothing.  I don't know anybody who says that.  But
just because it does some things (like deliver iron and Aspergillus)
doesn't mean it does everything or causes everything.
     Your statement about lionfish, that "For them to reach those islands
(the windward islands), they would have to have moved against strong
prevailing east-to-west currents." is incorrect, as I demonstrated in a
previous message.  Currents are variable, and although that current moves
relatively strongly, current variation is enough to bring organisms
passively there.  Those islands have virtually all the reef species of the
rest of the Caribbean, they all had to get there, and that includes many
invertebrates like corals whose larvae are not strong enough swimmers to
swim against currents as you suggest.  I doubt that they came in African
dust, and they didn't swim there.  But current variability means that at
least sometimes, currents move in different directions, and larvae are
carried in directions they normally aren't carried.  So there is no need to
hypothesize lionfish eggs or larvae swimming up stream, nor the Diadema
pathogen, nor Tubastraea larvae, nor all the other Caribbean reef fauna,
but they all managed to get to the windward islands and all were carried
passively by water currents.

     NOAA assembled a group of scientists who produced a very comprehensive
assessment of background information on coral reefs and threats to coral
reefs, in their report on coral species proposed for endangered species
status.  They reviewed the role of African dust in coral reef processes in
the Caribbean.  You can read the report yourself, it is available
open-access online, it is public information:
www.nmfs.noaa.gov/stories/2012/04/docs/exec_sum_and_intro_corals_statusreviewreport.pdf

I quote from page 50 of that report:

"3.2.7 African and Asian dust

Scientists have long known that dust clouds travel long distances. Soils
found on many Caribbean islands may have been substantially enriched with
iron from African dust (Garrison et al., 2003), and studies show that
essential nutrients in Hawaiian rainforests are transported via dust from
Asia (Kurtz et al., 2001). Hundreds of millions of tons of dust transported
annually from Africa and Asia to the Americas may be adversely affecting
coral reefs and other downwind ecosystems (Garrison et al., 2003). Viable
microorganisms, macro- and micronutrients, trace metals, and an array of
organic contaminants carried in the dusty air masses and deposited in the
oceans and on land could affect coral reefs worldwide. Shinn et al. (2000)
proposed that atmospheric dust transported largely from Africa has severely
affected
Caribbean coral-reef organisms by acting as a vector for pathogens such as
Aspergillus sydowii, a fungus known to affect two sea fans (Gorgonia
ventalina and Gorgonia flabellum) (Geiser et al., 1998). Recent research,
however, found that of seven species of Aspergillus present in dust samples
collected from Mali and St. Croix in the U.S. Virgin Islands, Aspergillus
sydowii was not present (Rypien et al., 2008). Several other studies that
examined the fungal biota of African dust also did not detect Aspergillus
sydowii, although several other species of Aspergillus were present (Griffin
et al., 2003; Kellogg et al., 2004; Shinn et al., 2003; Weir-Brush et al.,
2004). These data taken in conjunction with recent molecular evidence,
suggest that African dust as a source of the marine pathogen Aspergillus
sydowii should be considered unlikely (Rypien et al., 2008). To date, the
identified (Serratia marcescens) or suspected (Vibrio charcharia) pathogens
of elkhorn and staghorn corals have not been identified among the microbes
in dust (Griffin et al., 2002).  Therefore, the BRT ranked the threat posed
by African and Asian dust as negligible for all areas throughout the ranges
of
the 82 candidate coral species, and left unabated, this threat is not
expected to significantly increase the extinction risk for any of these
species. There is also no well-established connection between anthropogenic
climate change and future levels of African or Asian dust."

Cheers, Doug

On Wed, Feb 5, 2014 at 9:51 AM, Eugene Shinn <eugeneshinn at mail.usf.edu>wrote:

> After reading remarks by Doug Fenner, Matt Johnson, and Samuel Purkis
> regarding my short note relative to lionfish and /Diadema,/ it occurred
> to me that readers might have missed my point. It has been 14 years
> since we hypothesized that the 1983 Caribbean-wide near die-off of
> /Diadema/ and acroporid corals, and initiation of sea-fan disease, were
> likely caused by something carried in African dust *(Shinn et al., 2000,
> African Dust May be Cause of Coral Death. Geophysical Research Letters,
> v. 27, no 19, p. 3029-3032).* The smoking gun, /Aspergillus sydowii/ (a
> soil fungus), shown by Smith et al. (1996) using Koch's postulate, was
> the cause of the sea-fan disease. That African dust had negative
> environmental effects was regarded as an outrageous idea. However,
> abundant research has been conducted over the past 14 years that shows
> the good as well as deleterious effects of African dust on the environment.
>
> African dust passing over the Cape Verde Islands is now widely
> recognized to hinder hurricane formation (some meteorologists still call
> it dry air). Iron in dust has been proposed to stimulate red tides, and
> iron is now recognized by chemical oceanographers (as originally
> proposed by John Martin) to stimulate primary productivity in the open
> ocean. Ligands in seawater are recognized for their ability to convert
> insoluble iron to bioavailable iron. That such dust clouds carried by
> trade winds often blanket the entire Caribbean has been repeatedly
> demonstrated in NOAA and NASA satellite images. The year 1983, a major
> El Niño year, correlated with coral bleaching in the eastern Pacific off
> Central America. Interestingly, major bleaching in the Caribbean and
> Florida did not occur until 1987. Besides being an El Niño year, 1983
> was the peak year of African dust flux to the Caribbean as measured at
> the Barbados monitoring station in operation by Joe Prospero since 1965.
> Dust flux at his station began rising in 1980 and continued to rise each
> year, culminating in the peak year 1983. Levels fell a little in 1984
> and 1985 (dropped to the 1981 level in 1986) but rose again in 1987
> before dropping back to 1979 levels. These were all significant years
> for coral distress, and diseases were reported well before 1983. In
> fact, black-band disease in brain coal was reported in Bermuda in 1973,
> which was also an earlier peak year for dust flux at Barbados.
> Correlation is not proof of causation of course, but correlation is
> certainly a stimulus for further research. In the case of African dust,
> no systematic experiments (controlled bioassays) other than the work on
> sea-fan disease have been conducted to test the hypothesis. Likewise,
> there have been no systematic controlled bioassays conducted on the
> effects of sewage pollution. The supposed association of sewage effects
> has also been one of correlation. Fortunately, some controlled
> experiments are now being conducted on the effects of sunscreen
> ingredients and pesticides on corals. One should wonder why such obvious
> experiments were not conducted years ago considering the seriousness of
> coral demise.
>
> However, we now know more about the composition of African dust which,
> although dominated by silica, also includes P, Fe, Hg, Au, Al, Be-7,
> Pb-210, and in fact, most all of Earth's elements. Be-7 is a radiogenic
> gamma-ray emitter with a short half-life of only 53 days. It is produced
> high in the stratosphere by cosmic-ray spallation of nitrogen atoms and
> is continually raining to Earth at low levels but somehow becomes
> concentrated in dust clouds that reach the Caribbean. The levels of Be-7
> in the red sediment that accumulates in rainwater cisterns on Caribbean
> islands is many orders of magnitude greater than that ordinarily found
> in lawn grass. People in the Windward Islands and elsewhere in the
> Caribbean ordinarily breathe the dust during periodic dust-flux events
> whose densities often cause closure of airports on Caribbean islands.
> Residents there are well aware of its effects on respiratory systems.
> African dust also carries modern pesticides (some, such as DDT, still
> used in the Sahel region of Africa, are known immunosuppressants). The
> dust also transports many viable microorganisms.
>
> USGS microbiologists have identified a profuse and diverse microbial
> community in airborne African dust; many microbes identified to the
> species level (bacteria and fungi) are known pathogens for plants and
> humans. The impact or influence of viruses associated with these
> globally dispersed dust storms is just beginning to be explored. Given
> that we can only culture approximately 1% of bacteria in any given
> sample type, the true extent and influence of these microbes that fall
> out of the atmosphere in downwind environments has only been touched upon..
>
> So how does lionfish distribution support the dust hypothesis?
> Regardless of where the infestation began (probably in multiple
> locations), it took several years for the lionfish to be observed in the
> Windward Islands. Does anyone know exactly when the fish arrived there?
> I do not. For them to reach those islands, they would have to have moved
> against strong prevailing east-to-west currents. Alternatively,
> migration would require a circuitous route. After establishment in the
> Bahamas (where they were abundant before they were observed in the
> Florida Keys), they would then have to have worked their way
> southeastward to the northern Windward Islands and slowly emigrate
> southward along the island chain. From what I have read, it remains
> unclear whether they have bridged the current-swept gaps to reach the
> southernmost Windward Islands. At any rate, they apparently did not
> reach the Windward Islands as quickly as the /Diadema/ disease.
>
> Now consider the /Diadema/ die-off events as reported in a comprehensive
> paper *(Lessios et al., 1984, Spread of /Diadema/ mass mortalities
> through the Caribbean. Science, v. 226, p. 335-337)*.According to those
> authors, mortalities began in the vicinity of the Panama Canal in the
> southwestern part of the Caribbean (the disease agent was initially
> thought to have come from a ship's bilge water) and within one year
> spread over the entire Caribbean including the Windward Islands. To
> accomplish this, the unidentified infecting agent, unlike swimming fish
> or fish larvae, had to have traveled against the strong prevailing
> east-to-west current that passes through the Windward Islands chain.
> Spread of the disease also reached remote Bahamian islands such as San
> Salvador and Rum Cay within one year. I do not know how long it took
> lionfish to reach San Salvador, but I suspect it was more than a year.
> Surely someone on that island likely knows when the fish first arrived.
>
> These were the kinds of observations that initially led us to
> hypothesize that the infecting agent, whether elemental, chemical, or
> biological, had settled throughout the southern Caribbean from African
> dust clouds. The level of dust flux had been rising for several years
> before peaking in 1983. Dust levels remained high and did not subside to
> levels recorded between 1965 through 1968. Various coral diseases have
> not subsided since 1983, and although /Diadema/ exists in pockets
> throughout the Caribbean, pre-1983 levels have not been reported. They
> are extremely rare in the Florida Keys. One should remember that once
> material in the dust lands in the water, currents would then carry the
> agent northward in the manner that they transport Caribbean-derived
> lobster larvae that mature in the Florida Keys.
>
> For reasons discussed, the relatively delayed arrival of lionfish in the
> Windward Islands versus the rapid Caribbean-wide dispersal of the
> /Diadema/ disease lends support to our original hypothesis that whatever
> infected /Diadema/, acroporid corals, and sea fans had dropped out of
> the atmosphere. That the levels of dust flux had been increasing for
> several years likely caused local outbreaks of coral disease. Key
> observations of reefs in St. Croix support this supposition.
> Nevertheless, the peak of coral disease and the/Diadema/ die-off
> occurred in 1983. Donald Gerace, head of the Finger Lakes Laboratory at
> San Salvador, described to me how a well-known nearshore /Acropora/
> /cervicornis /reef had begun to die in a short period of time (less than
> 2 months) during the summer of 1983. Those corals were entirely dead
> when I swam over the reefs with Phil Dustan a few months later. In
> addition, most all /A/. /palmata /around the island was also dead but
> still standing. Some time later, I observed similar dead acroporids
> around nearby Rum Cay, where locals told the same story we heard at San
> Salvador. San Salvador and Rum Cay are both surrounded by deep-Atlantic
> water and are isolated eastward of the other Bahamian islands. In
> Florida, acroporids showed signs of stress in the late 1970s as revealed
> in serial photographs that date back to 1960. These photographs clearly
> show that the main period of sudden and synchronous demise at the photo
> sites occurred in 1983. At San Salvador, acroporid death was sudden.
>
> The red soil on San Salvador (called pineapple loam) is derived from
> African dust, and pottery there that pre-dates the arrival of Columbus
> was made from clay that had been fired. The only source of clay minerals
> in the Bahamas is African dust, the influx of which is not new. What is
> new is what the dust contains today.
>
> In conclusion, the apparent delayed arrival of lionfish to the Windward
> Islands versus the swift and synchronous outbreak of /Diadema/ disease
> throughout the Caribbean is considered supportive of the African dust
> hypothesis.
>
> The recent identification of /Serratia marcescens/ in Florida Keys coral
> is a good step toward solving an evolving mystery. However, evidence
> that human fecal bacteria, and other elements in sewage, caused
> acroporid death simultaneously throughout the entire Caribbean,
> especially at sparsely populated isolated locales such as San Salvador
> seems a stretch.
>
> Gene
>
> --
>
>
> 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
> <eugeneshinn at mail.usf.edu>
> Tel 727 553-1158
> ---------------------------------- -----------------------------------
>
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-- 
Douglas Fenner
Contractor with Ocean Associates, Inc.
PO Box 7390
Pago Pago, American Samoa 96799  USA

phone 1 684 622-7084