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  • 1
    Electronic Resource
    Electronic Resource
    Gamma densitometry for the measurement of skeletal density (1990)
    Springer
    Coral reefs 9 (1990), S. 11-23 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A method is described for the measurement of the density of calcium carbonate materials from the attenuation of a narrow, collimated beam of gamma photons. For the measurement of density for slices, approximately 0.5 to 1.0 cm thick, from the skeletons of reef building corals, the optimum beam energy is 30–34 keV; and measurement is practical from approximately 22 to 100 keV. The potential utilities of five commercially available isotopic sources (109Cd,125I,253Gd,210Pb and241Am) are evaluated. Methods and results are presented for gamma densitometry using210Pb and241Am. The210Pb point source had its principal gamma emission at 46.5 keV. Bremsstrahlung and high energy (800 keV) gamma emissions associated with the210Pb decay grand-daughter were detected, and procedures were developed to accommodate the contribution of these emissions to the overall count rate. The attenuation of count rate by aluminium and aragonite absorbers closely followed simple theoretical considerations provided that narrow energy window settings were used at the radiation monitor. These theoretical considerations take account of the density of the material absorbing the radiation, and hence the density could be determined from the attenuation of the gamma beam. Increased accuracy was achieved by the use of241Am and high speed counting equipment.241Am has its principal gamma emission at 59.6 keV. The attenuation of this gamma beam follows simple theoretical considerations for targets with mass thicknesses from 0 to 6 g cm-2. Aragonite from the shell of a giant clam was found to have slightly different properties in the absorption of gamma photons to aragonite from a coral skeleton. The differences were small but statistically significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686717
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  • 2
    Electronic Resource
    Electronic Resource
    Identification and quantitation of near-UV absorbing compounds (S-320) in a hermatypic scleractinian (1986)
    Springer
    Coral reefs 5 (1986), S. 155-159 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Reef-building corals from shallow waters are known to contain a suite of water soluble compounds (collectively named S-320) which strongly absorb near-UV light. Compounds of this type have now been isolated from the Pacific staghor coral Acropora formosa and identified as a series of mycosporine-like amino acids including mycosporine-Gly (λmax=310nm), palythine (λmax=320nm) and palythinol (λmax=332nm). These compounds were separated and quantified by high-performance liquid chromatography. Serial extraction efficiencies were calculated using a simple formula which is derived herein. For 12-cm long coral branches collected from a depth of 3 m at Rib Reef, Great Barrier Reef, Australia (146° 53′E, 18° 29′S) the average concentrations of mycosporine-Gly, palythine, and palythinol were 37.8, 56.4 and 0.895 nmol per mg coral protein, respectively. The coral samples can be stored at-20°C for at least 144 days without degradation of the mycosporinelike amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298182
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Depth-dependent responses to solar ultraviolet radiation and oxidative stress in the zooxanthellate coral Acropora microphthalma (1995)
    Springer
    Marine biology 122 (1995), S. 41-51 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Colonies of Acropora microphthalma (Verrill 1869) were transferred from depths of 2 to 3, 10, 20, and 30 m to UV-transparent and UV-opaque respirometry chambers placed at 1 m depth at Bowl Reef, Great Barrier Reef, in March 1989. Peak rates of photosynthesis in colonies originating at 2 and 10 m were unaffected by solar ultraviolet (UV) radiation at 1 m, whereas photosynthesis showed 30 and 38% inhibition in colonies transferred from 20 and 30 m, respectively. This differential sensitivity of corals to UV radiation was consistent with the five- to tenfold higher concentrations of UV-absorbing, mycosporine-like amino acids (MAAs, putative defenses against UV) in 2- and 10-m colonies compared with 20- and 30-m colonies. Photosynthesis in zooxanthellae freshly isolated from 2- and 10-m corals, however, was inhibited by UV, indicating that the host's tissues, which contain 95% of the total MAAs in corals at these depths, are the first line of defense against solar UV and provide protection to their endosymbiotic algae. The general bathymetric decline in the activities of the antioxidant enzyme superoxide dismutase (SOD) in the host, and SOD, catalase, and ascorbate peroxidase in the zooxanthellae, is related to the decrease in potential for photooxidative stress with increasing depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349276
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  • 4
    Electronic Resource
    Electronic Resource
    Simulating light-saturation curves for photosynthesis and calcification by reef-building corals (1981)
    Springer
    Marine biology 63 (1981), S. 135-141 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-saturation curves for photosynthesis by reef-building corals have previously been simulated by three functions: the right rectangular hyperbola, a simple exponential function, and the hyperbolic tangent function. Studies of photosynthesis by other organisms have also frequently considered the application of a rectilinear function. This communication analyzes lightsaturation curves for photosynthesis by the Atlantic rose coral Manicina aerolata, the Atlantic staghorn coral Acropora cervicornis, and the Pacific staghorn coral A. formosa. It also analyzes light-saturation curves for calcification by A. cervicornis and A. formosa. This communication demonstrates that the two most accurate functions (as measured by coefficients of determination) are the simple exponential function and the hyperbolic tangent function. The hyperbolic tangent function is preferred because parameter estimates obtained with this function have narrower confidence intervals than those obtained through the application of the simple exponential function. The hyperbolic tangent function can also be used successfully to simulate light-saturation curves for light-enhanced calcification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406821
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    Paper (German National Licenses)
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