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Marine Ecology Progress Series

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MEPS 239:301-310 (2002)  -  doi:10.3354/meps239301

Environmental and biological effects on the stable oxygen isotope records of corals in the northern Gulf of Aqaba, Red Sea

Saber Al-Rousan1,2,*, Salim Al-Moghrabi2, Jürgen Pätzold1, Gerold Wefer1

1Fachbereich Geowissenschaften, Universität Bremen, 28359 Bremen, Germany
2Marine Science Station, PO Box 195, Aqaba, Jordan

ABSTRACT: Monthly δ18O records of 2 coral colonies (Porites cf. lutea and P. cf. nodifera) from different localities (Aqaba and Eilat) from the northern Gulf of Aqaba, Red Sea, were calibrated with recorded sea surface temperatures (SST) between 1988 and 2000. The results show high correlation coefficients between SST and δ18O. Seasonal variations of coral δ18O in both locations could explain 91% of the recorded SST. Different δ18O/SST relations from both colonies and from the same colonies were obtained, indicating that δ18O from coral skeletons were subject to an extension rate effect. Significant δ18O depletions are associated with high extension rates and higher values with low extension rates. The relation between coral skeletal δ18O and extension rate is not linear and can be described by a simple exponential model. An inverse relationship extends over extension rates from 1 to 5 mm yr-1, while for more rapidly growing corals and portions of colonies the relation is constant and the extension rate does not appear to have a significant effect. We recommend that δ18O values be obtained from fast-growing corals or from portions in which the isotopic disequilibrium is fairly constant (extension rate >5 mm yr-1). The results show that interspecific differences in corals may produce a significant δ18O profile offset between 2 colonies that is independent of environmental and extension-rate effects. We conclude that the rate of skeletal extension and the species of coral involved have an important influence on coral δ18O and must be considered when using δ18O records for paleoclimatic reconstructions.

KEY WORDS: Stable oxygen isotopes · Coral extension rate · Coral calcification rate · Porites spp. · Gulf of Aqaba · Red Sea

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