Using CT imagery to evaluate the relationship of sea surface temperature with annual linear extension of the coral Orbicella in Dry Tortugas, Florida
Using CT imagery to evaluate the relationship of sea surface temperature with annual linear extension of the coral Orbicella in Dry Tortugas, Florida
Raie Hess
Aiden Moriya
Raie Hess¹, Aiden Moriya¹, Sierra Bloomer², Lauren Toth², Chelsea Korpanty¹
¹Eckerd College, Marine Science Department
²U.S. Geological Survey
Reef-building stony corals, such as Orbicella, grow by secreting annual calcium carbonate layers, or bands, that can be measured to calculate linear extension (growth) rates. Decreases in extension rate tend to occur with extremes in sea surface temperature (SST) beyond the coral’s optimal ecological zone. This study aims to evaluate the accuracy relationship between coral linear extension rates and regional SST in the Dry Tortugas, Florida. Coral cores were collected from two Orbicella faveolata in 2008 by the United States Geological Survey, cut longitudinally, and CT scanned. We identified coral bands in the CT images and calculated linear extension rates using the program CoralCT. Preliminary results of the most recent 50 bands (last 50 years since 2008) indicate that linear extension rates are variable and are generally lower when SST peaks and higher when SST falls. Of note, linear extension rates were particularly low in 1998, coinciding with the 1997-1998 coral bleaching event. Our findings suggest that variations in linear extension rates in our coral cores generally align with SST fluctuations. However, this alignment is sometimes inconsistent (i.e., relatively high linear extension rates when SST peaks), suggesting that the relationship between coral growth and SST may be complicated by other physiological and environmental factors. Further research is needed to assess linear extension rates within various stony coral genera to SST to continue to evaluate this relationship as a paleoclimate proxy.