Reef-wide and long-term skeletal growth records of the mountainous star coral (Orbicella faveolata) from Belize barrier and atoll reefs (Central America)

Coral reefs are vulnerable marine ecosystems and reef-building corals are especially sensitive to the impacts of environmental change. Skeletal growth records of corals (Scleractinia) can be used as archives of ecological and climatological change. This study focusses on massive Orbicella faveolata coral skeletons from the Belize barrier and atoll reefs. In total, 11 drill cores from 10 coral colonies were studied. Their skeletal growth records range from 17 to 186 years and span time windows from the early 19th century to the beginning of the 21st century. Based on these records, master chronologies have been compiled for the entire 20th century. The data indicate uniform skeletal growth across the various reef environments of offshore Belize. Skeletal density is increasing reef-wide, whereas linear extension is declining, accompanied by a slightly declining calcification rate. Apparently, a more densely packed coral skeleton does not compensate for the reduced linear growth and calcification sufficiently in O. faveolata populations across the Belize reefs. The longest analysed coral sample contains >186 years of skeletal growth, which exhibits periodicities of 40-80 years. Such cycle lengths likely reflect the Atlantic Multidecadal Oscillation, lending further support to coral skeletal records being valuable archives for long-term oceanographic change.