The Relationship between the Maze Coral (Meandrina meandrites) Autumnal Bleaching Cycle and Seawater Temperature, Gulf Stream Reef, Boynton Beach, Florida

The Relationship between the Maze Coral (Meandrina meandrites) Autumnal Bleaching Cycle and Seawater Temperature, Gulf Stream Reef, Boynton Beach, Florida

Seasonal coral bleaching has been observed and studied in tropical waters around the world. These studies have demonstrated that there is a strong correlation between anomalously elevated sea water temperature and coral bleaching events, however few studies have been performed on healthy corals during periods of normal sea water temperature fluctuation. Visible changes of pigmentation were used as a proxy measure of dinoflagellate densities in the maze coral Meandrina meandrites inhabiting the Gulfstream reef off Boynton Beach, Florida on 15 observations from mid-August 2007 to mid-January 2008. Unlike previous studies at this location, submersible temperature recorders were deployed, which provided continuous seawater temperature data. Highest seawater temperatures were observed in August and September (28-30°C), with a decrease to 22-24°C observed in January 2008. Coral tissue pigmentation level changes were recorded via digital photography. Total colony surface areas were compared with visibly bleached surface areas. Bleached coral tissue ranged from 0-3.7% with a decrease in pigmentation from mid-August through mid-November, and then pigmentation recovery through the end of the study in January. This pattern is consistent with previous observations by other researchers, though greater amounts of bleached tissue (0-28.7%) were reported in 2003.