Otolith δ ¹⁸ O Record of Mid-Holocene Sea Surface Temperatures in Peru

Abstract

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 degrees 55'S] indicate that summer SSTs were approximately 3 degrees C warmer than those of the present. Siches otoliths (6450 +/- 110 yr B.P.; 4 degrees 40'S) recorded mean annual temperatures approximately 3 degrees to 4 degrees 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 approximately 5000 yr B.P.

Integration of proxy data and model scenarios for the mid-Holocene onset of modern ENSO variability

“…Reduced early-Holocene ENSO activity was accompanied by mean warm conditions in the eastern equatorial Pacific according to some reconstructions (Sandweiss et al, 1996;Rodbell et al, 1999;Andrus et al, 2002). These views are contrary to reconstructions of La Nin˜a-like conditions between 8-5 ka BP with an increased zonal gradient and few warm events (Koutavas et al, 2002).…”

“…3) (Koutavas et al, 2002). Evidence for warmer rather than cool eastern equatorial Pacific conditions prior to 5 ka BP comes from Peruvian otolith d 18 O data (Andrus et al, 2002). However, vital effects of the fish species (Galeichthys peruvianus) on the otolith d 18 O signature are largely unknown and subject to the migration and spawning habits of the species (Be´arez et al, 2003).…”

Environmental change and economic development in coastal Peru between 5,800 and 3,600 years ago

“…When sea level transgression ceased in the Mid-Holocene, this geophysical configuration changed significantly. Approximately 5,800 years ago, the return of El Niño (the warm phase of the El Niño-Southern Oscillation phenomenon, or ENSO) after a hiatus of several millennia (4,5) coincided with emplacement of the modern fishery dominated by small schooling fish (6,7) and of the contemporary coastal regime dominated by powerful north-flowing longshore currents and strong daily winds blowing inland NNE off the sea. Establishment of these conditions created the beach ridge and sand dune geomorphic regime that has characterized the north coast of Peru since the Mid-Holocene (e.g., ref.…”

The Effect of Orbital Forcing on the Mean Climate and Variability of the Tropical Pacific

“…Past ENSO variability has been reconstructed for time slices throughout the last 120 000 yr (Sandweiss et al 1996;Hughen et al 1999;Rodbell et al 1999;Rittenour et al 2000;Corrège et al 2000;Cole 2001;Tudhope et al 2001;Moy et al 2002;Andrus et al 2002;Cobb et al 2003). These reconstructions suggest that ENSO was active during the last interglacial about 125 000 years ago and was probably reduced in its activity during the early to mid-Holocene (9000-7000 yr ago).…”