SREL Reprint #2759

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

C. Fred T. Andrus, Douglas E. Crowe, and 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.

Keywords: El Niño, ENSO, otolith, stable isotopes, Peru, Galeichthys perovianus

SREL Reprint #2759

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):5.1-5.8.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).