EXPANDED LATE HOLOCENE CORAL REEF DEVELOPMENT IN SOUTHEASTERN FLORIDA LINKED TO REGIONAL CLIMATE CHANGE

The mid-Holocene demise of acroporid reef development in southeastern Florida has been linked to long-term regional cooling of the subtropical Atlantic following the Holocene Thermal Maximum (HTM). However, the recent discovery of extensive late Holocene subfossil acroporid and orbicellid coral assemblages overlying submerged nearshore beach deposits off the coast of Broward County suggests that local conditions were conducive to reef development ~1800 years after the HTM. Using high-precision U/Th dating of 30 subfossil corals from this site, we link late Holocene fringing reef development off the coast of Broward County to regional paleoclimate records. Results suggest that reef development between ~3.2 and 2.2 ka corresponds to a southward migration of the ITCZ and distinct weakening of the North Atlantic Oscillation (NAO). This likely led to a dryer hydroclimate over the Florida Everglades watershed, thereby reducing terrestrial runoff to the nearshore reefs. Localized cooler winter associated with weak and negative NAO was likely mitigated by the Florida Current, a process that has been documented on modern reefs throughout the region.