Skeletal-extension rates of Bermuda framework-building massive corals during the Holocene: Review and new data from rotary drilling

The skeletal-extension rates of the three main framework-building corals from the mid-late Holocene show distinct responses, either under the same environmental conditions, or within the same species under different conditions. Diploria labyrinthiformis , the only species found in both open and inshore-water environments, shows higher extension rates in the inshore waters of Castle Harbour (4.18 ± 0.56 to 5.55 ± 1.16 mm/year), compared to open water conditions at North Rock (2.53 ± 0.33 to 3.49 ± 0.68 mm/year). Some of these inshore extension rates also exceed those of the same contemporary species elsewhere in Bermuda and the Western Atlantic. Conversely, the extension rates of Pseudodiploria strigosa (2.71 ± 0.91 to 3.76 ± 0.68 mm/year), and the Orbicella annularis group (1.64 ± 0.32 to 2.75 ± 0.86 mm/year), are generally within the range of their contemporary counterparts in Bermuda but lower than those found in the Western Atlantic. Possible reasons for coral extension rate differences between locations turbidity, water circulation, depositional energy, sediment-clearing abilities of corals, and temperature as well as relationship of coral extension growth to reef accretion are discussed. • Skeletal extension rates of 14 selected Holocene fossil Bermuda corals were analysed • Holocene inshore framework corals have higher extension than those in open water • Holocene corals of the Orbicella annularis group show the lowest extension rates • Environmental energy and sediment suspension likely governed extension rate variation • Skeletal extension rate responses support the concept of “suppressed reef accretion”