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August
21, 2009: NASA scientists Maury Estes and Mohammad
Al-Hamdan have been seafaring in the Gulf of Mexico, and one
of them grew a bit green around the gills. It's not surprising
that a space agency scientist might have trouble getting his
sea legs, but what was he doing out there in the surf to begin
with?
"We
were gathering water samples," explains Estes.
That
doesn't sound much like rocket science, but consider the following:
 At
this moment, a fleet of NASA Earth-observing satellites is
silently passing overhead, gathering vital information about
our planet. Estes and Al-Hamdan are combining that heavenly
data with local water samples to help the Mobile Bay National
Estuary Program, or NEP1, check the health of the
coast.2
Right:
Estes (center), Al-Hamdan (right), and a Mississippi State
graduate student (left) check water samples. The instrument
in the picture is lowered into the water and samples trapped
at various depths.
"We're
most interested in sea grass and marine vegetation,"
says Al-Hamdan. "A region's plant health tells you a
lot about the health of the area itself."
"It's
fair to say that if seagrass is in trouble, so is everything
else in the area," explains Dr. Ken Heck3 of the
Dauphin Island Sea Lab in Mobile. "Sea grass beds provide
shelter and food for many ecologically and economically important
fish and shellfish, and even for the manatee -- an endangered
gentle giant4 that regularly visits Mobile Bay.
These beds also stabilize the shoreline, prevent erosion,
and even help filter and cleanse the water that enters our
estuaries from the watershed."
According
to Estes and Al-Hamdan, the way the land is used throughout
the watershed influences how much fresh water flows into the
salt water areas and what that fresh water contains. Homes,
farms, forests, small towns, big cities, etc., all affect
the water in distinctive ways. "For instance, sediments
cloud the fresh water flow," explains Estes. "And
fertilizers can boost invasive species and algae that choke
out the 'good' plants like sea grass."
"So
we knew we'd get environmentally valuable information by looking
at how the land was used in the past and how it's used now,"
says Al-Hamdan. "Historical NASA satellite data5
told us what we wanted to know."
That
"heavenly" data, along with local water samples,
revealed land use-related trends in water flow quality and
properties like salinity, temperature, and clarity. These
factors have both a literal and figurative trickle-down effect
on marine plant life and therefore overall habitat health.
Above:
The wetland environment of coastal Mobile Bay. [larger
image]
"This research helps us model, or predict, how different
types of land use might affect the coastal environment in
the future, not only in the Mobile Bay area but also in other
coastal areas," says Al-Hamdan.
"The
work NASA's doing will help coastal resource managers direct
the limited resources available for habitat conservation and
restoration," says Mobile Bay NEP Director Roberta Swann.
"It will help us focus restoration efforts where they're
most needed and most likely to succeed."
When
Estes and Al-Hamdan aren't in the office poring over satellite
images to help foresee the coastal future, they're heading
out to sea, where they collect water samples to analyze for
"ground truth" to validate their model. The ocean
voyages also give them a first-hand view of what they're studying
and why.
"You
do science in the real world – not in the office," explains
Estes. "Going out there gives you a good perspective
on the research data. If you don't physically know the area
you're studying, it limits your understanding."
"From
the boat, we got to see the coastal areas we're targeting.
Turns out that the northern third of the Mobile Bay environment
is natural shore, but the southern two thirds is primarily
sea walls, rip raps [man-made piles of big rocks], and revetments
[sea wall /rip raps combination]. Plant and animal life can't
flourish in rocks and concrete."
Above:
A Mobile Bay revetment--i.e., a sea wall made of rocky rip
raps.
Estes
sees the modification of natural coastline as a self-perpetuating
problem.
"Development
feeds on itself," says Estes. "If your neighbor
builds a sea wall to help protect his own shore from eroding,
your shore starts eroding, so you put up a sea wall too. And
it's much more difficult to get a permit to restore a natural
beach or marsh area on one's property than to get permission
to build a sea wall. Plus there are all kinds of docks and
boat launches along the coast."
The
scientists spent an entire day, recently, on the open ocean
gathering water samples and mentally cataloging the coast
line. They're quite serious about their work but will take
a few moments for fun.
"I
got a nice tan out in the boat," jokes Al-Hamdan. "It
sure beats green."
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Author: Dauna Coulter
| Editor:
Dr. Tony Phillips | Credit: Science@NASA
| end
notes |
|
(1)
Mobile Bay National
Estuary Program: Al-Hamdan and Maury Estes are lending
their remote sensing expertise to help the Estuary Program
and other members of the Gulf of Mexico Regional Collaborative
(GoMRC) understand what might be affecting the health
of sea grass and other marine vegetation in the coastal
areas, including the estuaries. Established in 2006
with NASA funding, the GoMRC
will use the study results to decide where to focus
habitat restoration efforts.
(2)
This demonstration project in Mobile Bay, AL is a collaborative
effort between NASA Marshall Space Flight Center, Universities
Space Research Association, NASA Stennis Space Center,
Battelle at the Pacific Northwest National Lab, Tetra
Tech Engineering, Prescott College, Mobile Bay National
Estuary Program and other Gulf coast partners.
(3)
Heck is Chief Scientist at the Dauphin Island Sea Lab
and a Professor in the Department of Marine Sciences
at the University of South Alabama. Dauphin Island Sea
Lab is Alabama's marine education and research center.
Located on the eastern tip of a barrier island in the
Gulf of Mexico, the Sea Lab is the home site of the
Marine Environmental Sciences Consortium. The Consortium
serves Dauphin Island Sea Lab members, both public and
private. Additionally, the DISL's Coastal Policy Center
offers local government, industry and agency decision
makers a range of coastal zone management services.
(4)
For more information on these gentle giants, see http://www.manatees.net/
and the Mobile Manatees Sighting Network at http://manatee.disl.org
.
(5)
To find out how the watershed land was used through
the years, the team studied 1948 historical land use
data from University of Alabama Geography Department
archives, along with 1992 and 2001 satellite data from
NASA's Landsat* . Their growth model (The Prescott Spatial
Growth model), which projected land use to 2030, used
the 2001 land use data as a baseline. This allowed them
to develop land use scenarios for input into their watershed
model for predicting the future runoff characteristics.
They used the model to figure out how changes in land
use affected runoff water in terms of changes in the
water’s salinity, temperature and sediment throughout
the Mobile Bay, and in turn, the sea grass. [more
information]
More
information from Mobile Bay National Estuary Program
about the Mobile Bay Watershed:
•
It is the 4th largest watershed in terms of volume
in the United States: Mobile Bay receives an average
of 460,000 gallons per second of fresh water from
the watershed.
• It has one of the richest freshwater fish populations
in North America, home to 236 species of freshwater
fish, alone. Alabama also ranks second among all U.S.
states in the total number of fish species (fresh
and saltwater).
• It contributes to Alabama's ranking as second in
the nation in biodiversity (species per square mile),
due to its wide array of habitats.
NASA's
Future: US
Space Exploration Policy |
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