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Oxygen isotope record of the 1997-1998 El Nino in Peruvian sea catfish (Galeichthys peruvianus) otoliths
(American Geophysical Union, 2002-10-11) Andrus, CFT; Crowe, DE; Romanek, CS; University System of Georgia; University of Georgia; United States Department of Energy (DOE); Savannah River Ecology Laboratory; University of Alabama Tuscaloosa
[1] Sagittal otoliths of the Peruvian sea catfish Galeichthys peruvianus were collected from the north coast of Peru during and after the 1997-1998 El Nino. The otoliths were analyzed via laser microprobe and micromilling techniques for oxygen isotope composition through ontogeny to document their use as an El Nino-Southern Oscillation (ENSO) proxy. Results were compared to theoretical calculations for the delta(18)O of otolith aragonite using measured sea surface temperatures (SST) and delta(18)O values for local seawater assuming equilibrium oxygen isotope fractionation was achieved. All otoliths recorded the 1997-1998 El Nino event as well as seasonal temperature variations. These ENSO events were recorded in otolith aragonite as significant negative excursions in delta(18)O that reflected the increased temperature of local marine waters. The combined otolith data were used to create a 10-year SST record, including ENSO events and local seasonal temperature variation, validating the use of otolith delta(18)O as a temperature proxy.