Oxygen isotope record of the 1997-1998 EI Nino
in Peruvian sea catfish (Galeichthys peruvianus) otoliths
C. Fred T. Andrus, Douglas E. Crowe, and Christopher S. Romanek1
Department of Geology, University of Georgia, Athens, Georgia, USA
Received 2 May 2001; revised 9 January 2002; accepted 23 January 2002; published 11 October 2002.
[I] 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 S180 of otolith aragonite using measured sea surface temperatures (SST) and S180 values for local seawater assuming equilibrium oxygen isotope fractionation was achieved. All otoliths recorded the 1997 -1998 El Nmo event as well as seasonal temperature variations. These ENSO events were recorded in otolith aragonite as significant negative excursions in S180 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 &1 0 as a temperature proxy.
INDEX TERMS: 4522 Oceanography: Physical: EI Nino; 1040 Geochemistry: Isotopic composition/chemistry; 4870 Oceanography: Biological and Chemical: Stable isotopes; 9355 lnfonnation Related to Geographic Region: Pacific Ocean; 9360 lnfonnation Related to Geographic Region: South America;
KEYWORDS:
EI Nino, ENSO, otolith, stable isotopes, Pero, 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 17:5-1 - 5-8.
