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You
might not expect to find coral reefs teaming with an endless variety
of brightly colored fish among the oilrigs of the gulf, but if
you head seventy miles straight south from Sabine Pass near the
Texas and Louisiana state line, that is exactly what you will
find. A century ago, snapper fishermen said the reefs below looked
like flower gardens, and the name stuck. The reefs are now part
of the Flower Garden Banks National Marine Sanctuary, which consists
of the East, West and Stetson Banks. Together, they comprise one
of thirteen Flower Garden sanctuaries managed by the National
Oceanographic and Atmospheric Administration (NOAA).
The reefs have it all, from zooplankton
to the largest fish in the world, all flourishing in close proximity
to the offshore oilfields. Over the years, with the help of the
oil industry, the NOAA staff at the sanctuary has protected, monitored,
and facilitated research upon these surprising reefs.
The banks first thrust upward under
pressure from forming salt domes millions of years ago below the
ocean's floor, and now support a diversity of species unique on
the gGulf Coast. Another unique aspect of the reef system is that
it lies far from the shoreline. This isolation allows it to thrive
in the absence of pollutants that have damaged other systems closer
to shore. Dr. Quenton Dokken, at the Center for Coastal Studies,
notes that "it's remarkable that such a healthy and productive
reef system exists right in the middle of the most active offshore
exploration and production area in the world."
The northernmost of the three Flower
Garden Banks, the Stetson Bank, lies in slightly cooler waters.
The temperature difference prevents it from supporting as much
diversity as the other two banks. It supports mainly communities
of sponges. However, the east and west banks, near the water's
surface, are just what you might expect from a tropical reef,
with hundreds of species of fish, invertebrates and heads of coral
the size of automobiles. The loop current of the gulf stream allows
these reefs to thrive at the northernmost limits of coral reef
habitat.
Starting at depth of 90 feet on
the east and west banks, you can find patches of small branching
finger coral called Madracis Mirabilis. These areas also feature
finger sponges, encrusting sponges and algae. Divers find sponges,
algae and coral that flattens out to take advantage of all available
light as they dive deeper on the reef. At greater depths, the
diver finds strange animals like the bedspring-shaped antipatharian
sea whip. Below a depth of 270 feet, coralline algae survive,
but reef-building corals cannot. The deeper portions are what
is left of the ancient reefs, which probably formed when sea levels
were lower and these ancient reefs lay closer to the surface.
On the Gulf's floor at 300 to 400
feet down, only sand or mud bottom surrounds the reef. Though
it looks barren, the surrounding bottom hosts a healthy community
of organisms surviving in the sediment. Micro algae, worms, crabs
and sea stars all manage to flourish at these depths. On the East
Bank at depth of 220 feet lies a salt lake 200 feet wide by only
10 inches deep, formed from the brine that seeps out of the salt
dome beneath. The forbidding, heavy, highly saline water with
its high concentrations of hydrogen sulfide and hydrocarbon gases
does not support marine life.
However, the bottom of the reef
is not the only forbidding area. In winter, bad weather on the
water's surface harries but does not stop researchers from documenting
the shark and ray populations. Schools of scalloped hammerhead
sharks and spotted eagle rays gather around the Flower Garden
and Stetson Banks. Sandbar and tiger sharks also come to the banks
in winter. Large schools of silky sharks congregate around the
High Island platform at the edge of the sanctuary, only a mile
from the East Bank. Manta rays feed at the edges of the banks
all year, southern stingrays lie in the sand flats, and devil
rays visit the sanctuary in the early summer. As summer wears
on, recreational divers may even have encounters with the largest
of all fish, the whale shark. Whale sharks at lengths of 35 feet
have been sighted at the Banks.
This diversity of marine life, unusual
on the Gulf Coast, makes the Flower Garden Banks a popular destination
among scientists and recreational divers. Often, because of sometimes-scarce
funding, the Flower Garden Banks National Marine Sanctuary researchers
charter recreational dive boats to double as research boats. Sometimes
the researchers use NOAA ships, but much of the time the whole
operation depends heavily upon cooperation with the oil industry.
Among the guardian angels of the
Flower Garden staff over the years have been the platform operators
in the area. Scientists occasionally hitch rides out to the platforms
and store equipment onboard the platforms after their forays out
to the reef. G.P. Schmahl, the Sanctuary Manager, is continually
developing relationships with the gas and oil industry and welcomes
all assistance. The oil industry is integral to the NOAA's research
and monitoring efforts, the oil platforms serving as a base for
biologists and divers and also as a mount for monitoring instruments.
For additional information or to
offer assistance to the Flower Garden Banks National Marine Preserve,
call 979-779-2705, fax 979-779-2334, or go online at Scientists
occasion-www.flowergarden.nos.noaa.gov.
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