|
|
 |
|
|
|
|
|
|
|
| Significant Mortality Events: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Transcript - Online Mini-Documentary Movie:
"The Effects of Globally Transported African and Asian Dust on Coral Reef and Human Health"
USGS
science for a changing world
The Effects of Globally Transported African and Asian Dust on Coral Reef and Human Health
[narrator] Coral reefs worldwide are in decline. Over the last two decades, coral reefs in the
Caribbean Region and Gulf of Mexico have been damaged by human activities, hurricanes, abnormally high
water temperatures, and diseases. Where coral has died, algae has grown in its place. Scientists are
particularly concerned because Caribbean coral reefs, once damaged, are not recovering. Why is this
lack of recovery important?
[Ginger Garrison, USGS] Coral reefs are composed physically of the skeletons of millions of
little tiny coral polyps, which are little invertebrate animals. They provide a physical structure, which is
the coral reef, that is depended upon by literally millions of species of animals and plants. Now those
millions of species of plants and animals utilize the reef as both a shelter and also as a source of food.
Why are coral reefs important to humans? Well, first of all, they provide protection of our shorelines from
battering storm waves. They're a promising source of medicines. They provide exceptional value as
outdoor classrooms for education. They're economically important because they're a source for tourism
dollars and also of fisheries.
[narrator] Over the past few decades, the loss of live coral to disease has been significant and
there are increasing numbers of diseases or disease-like states being reported. In fact, scientists are just
beginning to identify the microorganisms causing diseases on reefs. Pathogens have been identified for
only three coral diseases: Sea Fan Disease (or Aspergillosis), Black Band Disease, and Plague.
Why are the diseases on the increase? Why are they so wide spread? Why are reefs, worldwide, in
decline? What is happening? Scientists at the U.S. Geological Survey are trying to answer these
questions.
[Gene Shinn, USGS] In 1996, there was a paper by Garriet Smith in "Science" where he had
identified the cause of Sea Fan disease that was all over the Caribbean. What he identified was a soil
fungus named Aspergillus. The important thing here is this Aspergillus does not reproduce in seawater.
It required a continual supply of spores. Garriet Smith hypothesized that it was runoff from deforestation,
however, this wouldn't explain this instance of the disease around small islands all over the Caribbean
where there were no forests. I suggested that maybe it was coming over in the African Dust. Since it's
soil, it should have spores and soil fungus. That would explain why this disease is popping up all over
the Caribbean, more or less simultaneously.
[narrator] For decades, atmospheric chemists and physicists have been studying the millions of
tons of dust that are carried each year from the Sahara and Sahel regions of Africa to the Caribbean and
Southeastern United States. A similar and larger system transports dust from the Gobi Desert in Western
China across the Northern Pacific and sometimes into the Pacific Northwest and beyond. We know from these
studies that most of the dust that reaches the Caribbean is very fine. Less than one micrometer or
one-twentyfive-thousandths of an inch. So small, that once inhaled, it is difficult for our lungs to expel the
particles.
[Chuck Holmes, USGS] African Dust has been found to be composed of clay minerals that are aggregated
and held together by a "glue" of iron oxide. Anything that is in the atmosphere will be absorbed onto these
particles, such as mercury. In dust, the mercury levels are four- to a thousand-times higher than as in
normal background in soils in the Southeastern United States. These elements are toxic and as a result
of the toxicity they should be looked at as to where they're going, how they're getting here, and what
happens to them after they get here to get into the biogeochemical cycle.
[narrator] Periodically, African desert locusts have been carried along with the dust and arrived
alive on several Caribbean islands. If a two-inch locust can survive the trip, what else may be hitching a
long-distance ride from Africa to the Americas with the dust? Perhaps smaller organisms such as microbes
that cause disease? Could dust be the source of the soil and the soil fungus?
[Gene Shinn] Garriet Smith started working with Ginger Garrison in the Virgin Islands and she
started collecting air samples during dust storms and sending them to Garriet. It turned out the very first
sample had this species of Aspergillus in it, and the significant thing is there were none in the samples taken
when there was not a dust storm. In other words, the clear air did not contain this soil fungus.
Since then, with the help and funding from NASA, we were able to bring in a microbiologist, Dale Griffin,
and he was able to culture about 120 species of viable bacteria.
[Dale Griffin, USGS] We're collecting from a couple different sites. One of course, is in the Caribbean,
in the Virgin Islands, and another is in Africa, in Mali. When dust from Africa is impacting the Caribbean, we
typically find anywhere from two- to up to ten-times more microorganisms in the air than we do when we
sample the same area when there is no dust in the air - clear atmospheric conditions. Normally when there's
dust in the atmosphere, about 80% of our isolates are bacteria, 20% fungi. And we've I.D.'ed over 100
to date and what we found that about 20% - 25% are species of bacteria or fungi, capable of causing disease
in plants or trees.
[narrator] Can this be true? Living microorganisms carried across the Atlantic and Pacific by dust?
We suspect this is the case. The next step is to sample and identify what is in the air mass as it is transported.
These results will provide the final link between our findings in Africa and the Caribbean. And, microorganisms
are probably not alone when hitching a ride.
[Ginger Garrison] Chemical contaminants may also be riding along on these small particles as they're
transported from Africa to the Caribbean and also from Asia to the Pacific Northwest of the United States.
There are pesticides that are used on agricultural crops. You have pharmaceuticals which are excreted in wastes.
You have heavy metals and toxic chemicals that are produced by the combustion of garbage. Now, garbage has
been burned for centuries. Primarily used as a fertilizer on agricultural land. However, recently, in the last two
decades, the composition of the garbage has changed from being primarily plant and animal waste to being
plastic bags, all sorts of plastic kinds of objects, even tires. And when those kinds of plastics are burned,
things such as dioxins and plasticizers are released. Now dioxins and plasticizers and many of these other
chemicals that we think may be riding across on the dust particles are known carcinogens that cause cancer
and many of them may be endocrine disrupters. And, that's a cause for concern because these are persistent
chemicals that can travel across the globe and have long-term effects on a number of ecosystems.
[narrator] Over four years ago, we hypothesized that African dust is impacting the health of coral
reefs and humans. Just how far-reaching are the effects of globally transported dust? USGS research is just
beginning to uncover the answers.
Produced By:
Ginger Garrison
Timothy Holmes
Narrated By:
Terry Edgar
Edited By:
Timothy Holmes
Additional Video Provided By:
Gary Nelson
Murphy Entertainment Group
William Stelzer
William Stelzer Design
WRD, USGS
Tampa, Florida
Melissa Enderle
Mark Ranneberger
Ray Smith
Don Hickey
Chris Reich
Satellite Imagery Provided By:
NASA
Additional Still Photography Provided By:
Cristina Kessler
Laurie Richardson
Garriet Smith
Julianna Weir
Richard Young
Special Thanks To:
USGS Eastern Regional Office
USGS Center for Coastal and Regional Marine Studies
USGS Florida Caribbean Science Center
Ecole Americaine,
Bamako, Mali:
Mellisa Enderie
Bobo Eyrich
Mark Ranneberger
Ray Smith
Ginger Garrison
Dale Griffin
Chuck Holmes
Chris Kellogg
Gene Shinn
For more information on the Internet visit:
http://coastal.er.usgs.gov/african_dust
Contact:
Ginger Garrison
ginger_garrison@usgs.gov
Gene Shinn
eshinn@usgs.gov
USGS
600 Fourth Street South
St. Petersburg, FL 33701
727-803-8747
USGS
science for a changing world
|
U.S. Department of the Interior | U.S. Geological Survey
