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PALEOCEANOGRAPHY, VOL. 17, NO. 4, 1053, doi:10.1029/2001PA000652, 2002

Oxygen isotope record of the 1997–1998 El Niño in Peruvian sea catfish (Galeichthys peruvianus) otoliths

C. Fred T. Andrus

Department of Geology, University of Georgia, Athens, Georgia, USA


Douglas E. Crowe

Department of Geology, University of Georgia, Athens, Georgia, USA


Christopher S. Romanek

Department of Geology, University of Georgia, Athens, Georgia, USA


Abstract

Sagittal otoliths of the Peruvian sea catfish Galeichthys peruvianus were collected from the north coast of Peru during and after the 1997–1998 El Niño. The otoliths were analyzed via laser microprobe and micromilling techniques for oxygen isotope composition through ontogeny to document their use as an El Niño-Southern Oscillation (ENSO) proxy. Results were compared to theoretical calculations for the δ18O of otolith aragonite using measured sea surface temperatures (SST) and δ18O values for local seawater assuming equilibrium oxygen isotope fractionation was achieved. All otoliths recorded the 1997–1998 El Niño event as well as seasonal temperature variations. These ENSO events were recorded in otolith aragonite as significant negative excursions in δ18O 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 δ18O as a temperature proxy.

Published 11 October 2002.

Index Terms: 4522 Oceanography: Physical: El Nino; 1040 Geochemistry: Isotopic composition/chemistry; 4870 Oceanography: Biological and Chemical: Stable isotopes; 9355 Information Related to Geographic Region: Pacific Ocean; 9360 Information Related to Geographic Region: South America.

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Citation: Andrus, C. F. T., D. E. Crowe, and C. S. Romanek (2002), Oxygen isotope record of the 1997–1998 El Niño in Peruvian sea catfish (Galeichthys peruvianus) otoliths, Paleoceanography, 17(4), 1053, doi:10.1029/2001PA000652.