Extension rate: A primary control on the isotopic composition of West Indian (Jamaican) scleractinian reef coral skeletons

Large variations in skeletal microarchitecture, and in the carbon and oxygen isotopic composition of the skeleton, exist within single calices and over the surfaces of single colonies of various species of West Indian (Jamaican) scleractinian reef corals. Rapidly extending parts of individual colonies are depleted in both C¹³ and O¹⁸ regardless of the abundance of zooxanthellae in the overlying tissues. We suggest that this relationship is due to active translocation of organic compounds to sites of rapid calcification. Considerable variation in isotopic composition is found in skeletons of different specimens of the same species even when the skeletons are sampled in a consistent manner, come from the same locality and depth, and have a comparable growth history. The isotopic composition of the scleractinian skeleton is vastly more complex than has heretofore been realized.