Browsing by Subject "coral"
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Item Coral Extension Rate Analysis Using Computed Axial Tomography(2014-01-10) Yudelman, Eleanor AnnBiological and geological studies of coral reefs often rely on measured Scleractinian coral skeletal extension rates. Ideally, corallites are oriented parallel to a coral core?s longitudinal axis and perpendicular to its annual high-density growth bands. To examine corallite orientations, we use high-resolution computed axial tomography to image ten short Montastrea faveolata cores from the northwest Gulf of Mexico. This non-destructive method enable the comparison of extension rates determined several ways: 1) across a single slice or slab X-ray image, 2) between 0.6 mm slice and 8.4mm slab X-ray images, and 3) among slice/slab orientated at varied angles relative to a coral core?s longitudinal axis. Additionally, the true three-dimensional extension rate of individual corallites is determined and compared to the extension rate apparent on a twodimensional slice/slab. Results suggest minimal significant differences between all methods, confirming the conventional extension rate methodology is suitable for studies if the core?s longitudinal axis is in approximate alignment with the growth axis of the corallites. Determination of three-dimensional corallite growth patterns leads to improved understanding of the development of the coral colony.Item Coral-based climate reconstructions from a massive Porites coral from Sabine Bank (Vanuatu)(2009-08) Dunn, Elizabeth M., 1984-; Quinn, Terrence M.; Taylor, Frederick W.; Kerans, CharlesA monthly resolved, 133 year record of coral Sr/Ca variations has been developed from a massive Porites coral that was drilled in the shallow waters of a submerged carbonate platform (Sabine Bank, 15.9°S, 166.14°E) located ~50 km west of Espiritu Santo, Vanuatu. This truly open-ocean site, at which daily measurements of temperature and salinity are available for ~ 6 years, permits the reconstruction of local environmental variability using variations in coral skeletal geochemistry. Coral Sr/Ca-SST variations are well matched to variations in local SST, but bear little relation to changes in local SSS indicating little or no influence of salinity on coral Sr/Ca. The complete coral Sr/Ca-SST time series is characterized by abundant inter-annual variability, a strong trend towards warming (i.e., lower Sr/Ca values) from ~1980-2006. Interannual SSTA variations at Sabine Bank correspond reasonably well to SSTA variations from the central Pacific cool tongue (Niño 3.4 region), indicating that coral Sr/Ca variations record ENSO variability in the region.