The radial growth rates and ages of 3 different groups of Hawaiian deep-sea ‘corals’ were determinedusing radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathesglaberrima were collected from 450 ± 40 m depth at the Makapuu deep-sea coral bed off the southeast coast ofOahu, Hawaii, USA, using a submersible vessel (PISCES V). Specimens of Antipathes dichotoma were collectedat 50 m depth off Lahaina, Maui, Hawaii. The primary source of carbon to the calcitic C. secundum skeleton isin situ dissolved inorganic carbon (DIC). Using ‘bomb 14C’ time markers we calculated radial growth rates of~170 μm yr-1 and ages of 67 to 71 yr for specimens of C. secundum up to 28 cm tall. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons, and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using 14C we calculated a radial growth rate of 15 μm yr-1 and an age of 807 ± 30 yr for a live collected Gerardia sp., showing that these organisms are extremely long lived. Radiocarbon measurements taken from the inner and outer portions of basal cross sections of 4 sub-fossil Gerardia sp. Samples showed growth rates (range 14 to 45 μm yr-1) and ages (range 450 to 2742 yr) similar to that of the live collected sample. Similarly, with a growth rate of <10 μm yr-1 and an age of ~2377 yr, L. glaberrima at the Makapuu coral bed is also extremely long lived. In contrast, the shallowcollectedA. dichotoma samples yielded growth rates ranging from 130 to 1140 μm yr-1 (12 to 32 yr). These resultsshow that Hawaiian deep-sea corals grow more slowly and are older than previously thought. |
