Otolith d18O Record of Mid-Holocene Sea Surface Temperatures in Peru

Photomicrograph of otolith excavated from the Ostra site Otolith d18O Record of Mid-Holocene Sea Surface Temperatures in Peru
Science, v.295(5559), pp.1508-1511, February 22, 2002

C. Fred T. Andrus,1* Douglas E. Crowe, 1 Daniel H. Sandweiss,2 Elizabeth J. Reitz,3 Christopher S. Romanek4

1 Department of Geology, University of Georgia, Athens, GA 30602-2501, USA.
2Department of Anthropology and Institute for Quaternary Research, S. Stevens Hall, University of Maine, Orono, ME 04469, USA
3Department of Anthropology and Georgia Museum of Natural History, Natural History Building, University of Georgia, Athens, GA 30602-1882, USA.
4Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA.

*To whom correspondence should be addressed. E-mail: andrus@gly.uga.edu

Peruvian sea catfish (Galeichthys peruvianus) sagittal otoliths preserve a record of modern and mid-Holocene sea surface temperatures (SSTs). Oxygen isotope profiles in otoliths excavated from Ostra [6010 ± 90 years before the present (yr B.P.); 8°55'S] indicate that summer SSTs were ~3°C warmer than those of the present. Siches otoliths (6450 ± 110 yr B.P.; 4°40'S) recorded mean annual temperatures ~3° to 4°C warmer than were measured under modern conditions. Trophic level and population diversity and equitability data from these faunal assemblages and other Peruvian archaeological sites support the isotope interpretations and suggest that upwelling of the Peru-Chile current intensified after ~5000 yr B.P.

Site Map Huanchaco Beach
Fig. 1. Map of the research area showing archaeological sites, modern collection sites, and JISOA SST data stations mentioned in the text. The inset shows an outline of the study area The beach near where the fisherman who collected specimens for this study lived. The boats drying on the stand in the background (the only type these fisheman use) are similar to the type seen on the earliest depictions on artifacts. [Photo: C.F.T. Andrus]

Download data from this study from WDC Paleo as an Excel file or in separate text files of Archaeological otoliths and cockle shells, Modern otoliths, and Water d18O data, Trophic Levels, and the Data Description.

Fig. 2 Photomicrograph of otolith Fig. 2. Photomicrograph of a modern otolith in thin section. The field of view is ~1 cm. d18O values follow ontogeny.

Fig. 3

Fig. 3. x axes represent time from birth (left) to death (right). y axes are d18O relative to PDB. Horizontal bars at the bottom indicate the macroscopic increment type as seen in transmitted light. White, austral winter; black, austral summer. Precision limits are equal to the size of data points in (B) and (C). (A) Composite mean of 10 modern otoliths. The 1991-1992 and 1997-1998 El Niños are labeled with arrows. Solid circles represent d18Ootolith; vertical lines represent 1sd from mean. Open circles represent d18O model. ( B) Plot of one Ostra otolith; ~6 year record. (C) Plot of one Siches otolith; ~8 year record. (D) Seasonal d18O variation, based on mean values of light and dark bands, from modern otoliths (dashed line), Ostra otoliths (thin line), and Siches otoliths (thick line). A 1-year period beginning and ending in the austral summer is shown.

Fig. 4

Fig. 4. Plot of mean trophic level, diversity, and equitability of vertebrate marine taxa at sites through time (x axis). At left, the y axis represents the trophic level (triangles). At right, the y axis represents the taxonomic diversity (diamonds) and equitability (squares). Sites, ranging from oldest to most recent, are as follows: Siches, Ostra, Siches-Lower Honda, Siches-Upper Honda, Alto Salaverry, and Pampa de Las Llamas-Moxeke.

Research funded in part by grants from the Geological Society of America (C.F.T.A.), Explorer's Club International (C.F.T.A.), NSF grant ATM-0082213 (D.E.C.), The Heinz Charitable Trust (D.H.S.), the University of Maine Faculty Research Fund (D.H.S.), and Department of Energy grant DE-FC09-96SR18546 (C.S.R.).

To read or view the full study, please visit the Science website. It was published in Science Vol. 295, Issue 5559, pp. 1508-1511, February 22, 2002. Note also the Technical Comment and Response in Science Vol. 299, Issue 5604, 10 January 2003.

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