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Coral Cd/Ca and Mn/Ca records of El Niño variability in the Gulf of California
J. D. Carriquiry and J. A. Villaescusa
Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Apdo. Postal No. 453. Ensenada, Baja California, México
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Abstract. We analyzed the trace element ratios Cd/Ca and Mn/Ca in three coral colonies (Pavona
gigantea, Pavona clivosa and Porites panamensis) from Cabo Pulmo reef,
Southern Gulf of California, Mexico, to assess the oceanographic changes caused by El
Niño – Southern Oscillation (ENSO) events in the Eastern Tropical North Pacific
(ETNP). The interannual variations in the coral Cd/Ca and Mn/Ca ratios show clear evidence
that incorporation of Cd and Mn in the coral skeleton are influenced by ENSO conditions, but
the response for each metal is controlled by different process. The Mn/Ca ratios were
significantly higher during ENSO years (p<0.05) relative to non-ENSO years for the three
species of coral. In contrast, the Cd/Ca was systematically lower during ENSO years, but it
was significant (p<0.05) only in P. gigantea. The decrease in the incorporation
of Cd, and the marked increase in Mn during the mature phase of El Niño indicate
strongly reduced vertical mixing in the Gulf of California. The oceanic warming during El
Niño events produces a relaxation of upwelling and a stabilization of the thermocline
which acts as a physical barrier limiting the transport of Cd from deeper waters into the
surface layer. In turn, this oceanic condition can increase the residence time of
particulate-Mn in surface waters, which in turn increases the photo-reduction of
particulate-Mn and the release of the available Mn into the dissolved phase. These results
provide validation for using Mn/Ca and Cd/Ca in biogenic carbonates as tracers of changes in
ocean stratification and trade wind weakening and/or collapse in the ETNP during ENSO
episodes.
 Notice on Discussion StatusThe requested discussion paper has a corresponding peer-reviewed
final revised paper in the journal Climate of the Past (CP). You are
encouraged to refer to the final revised version. Final Revised Paper (CP) Discussion Paper (PDF, 565 KB)
Citation: Carriquiry, J. D. and Villaescusa, J. A.: Coral Cd/Ca and Mn/Ca records of El Niño variability in the Gulf of California, Clim. Past Discuss., 6, 63-85, doi:10.5194/cpd-6-63-2010, 2010. Bibtex EndNote Reference Manager XML
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