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C and O isotopes in deep-sea corals (Lophelia pertusa) measured by ion microprobe
Blamart, D.; Rollion-Bard, C.; Cuif, J.P.; Juillet-Leclerc, A.; Lutringer, A.; van Weering, T.; Henriet, J.P. (2003). C and O isotopes in deep-sea corals (Lophelia pertusa) measured by ion microprobe. Erlanger Geol. Abh. Sonderband 4(109): 22
In: Erlanger Geologische Abhandlungen. Institut für Geologie der Universität Erlangen-Nürnberg: Erlangen. ISSN 0071-1160, more
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Document type: Summary
Keyword
    Marine/Coastal
Authors  Top 
  • Blamart, D.
  • Rollion-Bard, C.
  • Cuif, J.P.
  • Juillet-Leclerc, A.
  • Lutringer, A.
  • van Weering, T., more
  • Henriet, J.P., more
Abstract
    We have determined the d18O and d13C values of azooxanthellate corals (Lophelia pertusa ) at a micrometre scale using an ion microprobe (SIMS-Secondary Ion Mass Spectrometry). Coral skeletons are composed of two different microstructures:
    1. Centres of calcification, and
    2. surrounding fibres.
    In Lophelia pertusa centres of calcification are large (50µm) and arranged in lines of centres of calcification. Our results show that centres of calcification in Lophelia pertusa have a restricted range of variation in d18O (-2.8 ± 0.3‰ (V-PDB)), and a larger range in d13C (14.3 to 10.9‰ (V-PDB)). Surrounding skeletal fibres exhibit large isotopic variation both for C and O (up to 12‰), and d13C and d18O are positively correlated. The C and O isotopic compositions of the centre of calcification deviate from this linear trend at the lightest d18O values of the surrounding fibres. The variation of d18O at a micrometre scale is probably the result of two processes:
    1. An isotopic equilibrium calcification with at least 1 pH unit variation in the calcification fluid as indicated by direct measurements of coelenteron pH in the coral Galaxea fascicularis (Al-Horani et al., 2003), and
    2. a kinetic fractionation.
    The d13 apparent disequilibrium in Lophelia pertusa may be the result of mixing between depleted d13C metabolic CO2 (respiration) and DIC coming directly from seawater.
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