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MEPS 239:301-310 (2002)
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Abstract
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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
*E-mail: alrousan@uni-bremen.de
ABSTRACT: Monthly d18O 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 d18O. Seasonal variations of coral d18O in both
locations could explain 91% of the recorded SST. Different d18O/SST relations from both colonies and from the same colonies were obtained, indicating that d18O from coral
skeletons were subject to an extension rate effect. Significant d18O depletions are associated with high extension rates and higher values with low extension rates. The relation between coral skeletal d18O 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 d18O 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 d18O 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 d18O and must be considered when using
d18O records for paleoclimatic reconstructions.
KEY WORDS: Stable oxygen isotopes · Coral extension rate · Coral calcification rate · Porites spp. · Gulf of Aqaba · Red Sea
Full text in pdf format
Published in MEPS Vol.
239
(2002) on August 23
Print ISSN: 0171-8630; Online ISSN: 1616-1599.
Copyright © Inter-Research, Oldendorf/Luhe, 2002
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