Figure 3. Time-series of running 30-day mean seawater temperature from Molasses Reef since 1988 plotted against climatology.

Periods of known thermal stress are indicated. The MLRF threshold (red dashed line) is the coral bleaching threshold determined previously based on mass bleaching events in 1997, 1998, and 2005 (ref. ¹⁵). The 1990 threshold (blue dashed line) corresponds to temperatures that occurred when Milleporid hydrozoan corals bleached throughout the Florida Keys. Milleporid corals are known to be thermally sensitive, therefore this value may represent a threshold for these heat-sensitive corals.