A 107-Year-Old Coral from Florida Bay: Barometer of Natural and Man-Induced Catastrophes?

The 107-year growth history of a massive coral Solenastrea bournoni from Aorida Bay was reconstructed with x-ray imagery from a single 4-in.-diameter (10 cm) core that penetrated the exact epicenter of the 95.3-cm-high colony. The growth record core was collected in October 1986, and another "proof" core was drilled 1 year later to verify annual density banding in this species. Growth increments totalled 952.9 mm, averaging 8.9 mm/yr over the life of the coral. To our knowledge, this is the first time that growth rate of S. bournoni has been determined. Growth rate trends in the Aorida Bay coral were compared to those in a Montastraea annularis of similar age from Hen and Chickens, a nearby patch reef on the Atlantic Ocean side of the Florida Keys. Both corals were rated as potential indicators of natural and man-induced perturbations by comparing their growth rates in years of severe environmental stress to each coral's long-term growth rate average. It was concluded that growth rate, at least in these specimens, is a questionable indicator of past hurricanes and freezes. There does appear to be, however, a possible cause-and-effect relationship between major man-induced environmental perturbations and a prolonged reduction in growth rate in each coral's growth record.