NOAA/WDS Paleoclimatology - Andrus et al. 2002 Mid-Holocene Peruvian Otolith Oxygen Isotope Data

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.