11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
4-30
Corals At The Flower Garden Banks: Monitors Of Environmental Change And
North American Climate Variability
Amy WAGNER* 1 , Niall SLOWEY 1,2
1 Oceanography, Texas A&M University, College Station, TX, 2 Oceanography, Texas
A&M University, College Station
The Pacific/North American (PNA) pattern is a dominant atmospheric pattern of climate
variability in the extratropical Northern Hemisphere and strongly influences the winter
climate of the southeast United States. The instrumental record used to characterize the
PNA pattern does not exist prior to the mid-1940s. However, information about past
variability in the PNA pattern is preserved in the skeletons of long-lived corals at the
reefs of the Flower Garden Banks National Marine Sanctuary (NMS). The Flower
Garden Banks NMS is located approximately 180 km south of the Texas/Louisiana
border in the Gulf of Mexico and is the northernmost hermatypic reef on the United
States continental shelf. It has previously been shown that linear coral extension rates at
the Flower Garden Banks are highly correlated with winter air and sea surface
temperatures. In addition, average winter temperatures in the southeastern United States
are negatively correlated with the phase of the PNA pattern. During a positive phase of
the PNA pattern, the southeast US experiences stronger and more frequent winter storms
while a negative phase of the PNA pattern brings milder winters to the region. Thus, past
coral extension rates at the Flower Garden Banks provide a means to reconstruct the
history of temporal variations in the PNA pattern. We have collected several long cores
of skeletal material from long-lived Montastrea faveolata and Siderastrea siderea coral
heads from the Flower Garden Banks NMS. Annual extension rates have been
determined based on X- radiographic analysis of high/low density growth bands and are
used to characterize interdecadal variability associated with changes in the PNA pattern.
In addition, the presence of winter stress bands due to below average water temperatures
indicate winters with more severe and/or frequent storms. Analysis of these results will
contribute directly to our understanding of the temporal character of interannual and
interdecadal variations of North American winter climate.
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