Climate of the Past www.clim-past.net 1814-9324 1814-9332 6 3 2010 10.5194/cp-6-401-2010 http://www.clim-past.net/6/401/2010/ http://www.clim-past.net/6/401/2010/cp-6-401-2010.html http://www.clim-past.net/6/401/2010/cp-6-401-2010.pdf 401 410 2010-06-28 Coral Cd/Ca and Mn/Ca records of ENSO variability in the Gulf of California J. D. Carriquiry carriquiry@uabc.edu.mx J. A. Villaescusa Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Apdo. Postal No. 453, Ensenada, Baja California, México We analyzed the trace element ratios Cd/Ca and Mn/Ca in three coral colonies (<I>Porites panamensis</I> (1967–1989), <I>Pavona clivosa</I> (1967–1989) and <I>Pavona gigantea</I> (1979–1989)) 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). Interannual variations in the coral Cd/Ca and Mn/Ca ratios showed clear evidence that incorporation of Cd and Mn in the coral skeleton was influenced by ENSO conditions, but the response for each metal was controlled by different processes. The Mn/Ca ratios were significantly higher during ENSO years (<I>p</I>&lt;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 the difference was significant (<I>p</I>&lt;0.05) only in <I>Pavona gigantea</I>. A decrease in the incorporation of Cd and a marked increase in Mn indicated strongly reduced vertical mixing in the Gulf of California during the mature phase of El Niño. The oceanic warming during El Niño events produces a relaxation of upwelling and a stabilization of the thermocline, which may act as a physical barrier limiting the transport of Cd from deeper waters into the surface layer. 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