Coral cores from the Flower Gardens
A new tool for studying climate
by Niall C. Slowey and Thomas
[81K] A circular saw is used to
cut slabs from a coral core. The slab will be x-rayed to reveal annual bands
which preserve information about past climates. (Photo by Ken Deslarzes)
Reef corals have proven to be sensitive monitors of the marine environment. The
growth rate and chemical composition of their skeletons preserve a detailed history
of past environmental conditions. At Texas A&M, we are studying how climate
change related to variability in the atmospheric circulation of the extratropical
Northern Hemisphere is reflected by corals living in the Flower Garden Banks National
Marine Sanct-uary in the northwest Gulf of Mexico (See "Down
under out yonder," this issue).
[69K] Steve Gittings, manager of
the Flower Gardens National Marine Sanctuary, and Dick Zingula, a retired
Shell Oil employee, examine long cores of coral skeletal material raised
only moments earlier.
Yearly fluctuations in climatic and oceanic conditions associated with the
El Niño/Southern Oscillation phenomenon are known for their impact
on the fisheries, marine life, and weather of the equatorial Pacific and
other tropical regions.
Though less familiar, significant fluctuations in the climate of the mid-
and high-latitude regions also occur between periods of years and decades.
A shift in the atmospheric circulation of the extratropical Northern Hemisphere
during the late 1950s affected the severity of winters and influenced human
activities such as agriculture and fishing in broad areas of North America,
the North Atlantic, and Europe. The Gulf of Mexico and southeastern United
States are extremely sensitive to such climate variability, but little is
known about its impact on the gulf's marine environment.
Significant changes in the region's climatic elements do occur, including
variations in air temperature, rainfall, passage of atmospheric fronts,
and strength and direction of surface winds. It is likely that the marine
environment of the Gulf of Mexico is affected by this, with potentially
great economic and environmental consequences. For example, the gulf and
its coastal areas yield about 40% of the total commercial fisheries landings
in the United States and well over 100 million fish are caught each year
for recreation. Citrus farming and other forms of climate-sensitive agriculture
are important to regional economies. Furthermore, the environment shelters
numerous species of migratory birds and other animals, including reef corals
and endangered species of turtles and marine mammals. Other regions of the
Northern Hemisphere may also be affected by extra-tropical climate variability
in different but equally significant ways.
We want to develop long proxy records of past interannual and interdecadal
climate fluctuations and determine how they affected the Gulf of Mexico
region. This historical per-spective is valuable because it provides insight
into climate change on the socially relevant time scale of years to centuries.
In this way, we hope to contribute to efforts to recognize and anticipate
future climate change and develop sound policies for managing marine resources.
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Oceanography, Texas A&M
Updated December 20, 1995