Title
Changes in biological productivity and ocean-climatic fluctuations during the last ~ 1.5 kyr in the Humboldt ecosystem off northern Chile (27°S): A multiproxy approach
Date Issued
01 November 2017
Access level
metadata only access
Resource Type
journal article
Author(s)
LMI PALEOTRACES
Publisher(s)
Elsevier B.V.
Abstract
A sedimentary box core (BIAC072014) collected in a coastal environment in the Humboldt Current Ecosystem (HCE, Inglesa Bay, ~ 27°S, northern Chile) was used to reconstruct the changes in biological productivity and ocean-climate fluctuations during the last ~ 1.5 kyr via geochemical, mineralogical and micropaleontological analyses. From ~ 510 CE to ~ 930 CE, “El Niño-like” conditions prevailed, while during the Medieval Climate Anomaly (MCA, ~ 950 CE to ~ 1450 CE), “La Niña-like” conditions predominated. This pattern might have resulted from weakening/strengthening of the Walker cell, contraction/expansion of the South Pacific Sub-tropical High (SPSH) and a predominance of warm/cold phases of the Pacific Decadal Oscillation (PDO). Between ~ 1820 CE and the present, Inglesa Bay experienced a reduction in the Oxygen Minimum Zone (OMZ) intensity and biological productivity, an increase in the detritic input and a decrease in sea surface temperature (SST). Despite the regional intensification and secular cooling (~ 14°S and ~ 27°S) of coastal upwelling, the similarity between the reduction in biological productivity and OMZ intensity in this region and that in the central zone of Chile (~ 36°S) suggests that Inglesa Bay acts a transition zone in relation to the oceanographic behaviour of the HCE. The reduction in the OMZ intensity and biological productivity during the last ~ 200 years could be explained by greater subsurface ventilation in intermediate depths due to more northward displacement of the subduction region of the Eastern South Pacific Intermediate Water (ESPIW) near ~ 30°S in response to the strengthening of the circulation of the Subtropical Gyre. The coastal cooling observed in the northern section of HCE during the current Warm Period suggests that it is not possible to demonstrate that El Niño-like conditions promoted the reduction in biological productivity and OMZ intensity in Inglesa Bay.
Start page
798
End page
815
Volume
485
Language
English
OCDE Knowledge area
Oceanografía, Hidrología, Recursos hídricos
Subjects
Scopus EID
2-s2.0-85026881862
Source
Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN of the container
00310182
Sponsor(s)
We thank the editor and two anonymous reviewer for their valuable comments that led to marked improvement of this paper. To Mrs Marcos Guiñez and Mauricio Cerda for their collaboration in the sedimentological campaigns in Inglesa Bay. We thank Irina Djouraev, Fethiye Cetin, Hughes Boucher, Magloire Manden-Yogo, V. Klein, F. Medina and Sandrine Caquienau for analytical assistance on the L'OCEAN, France. We also thank Juan Carlos Leon for his support in taking radiographic images of the sediment box core at the clinical laboratory “Blanco”. The first author was the beneficiary of the thesis grant 21110059 from the National Commission for Scientific and Technological Research “CONICYT”. This paper is dedicated to the memory of our master and friend Luc Ortlieb.
Sources of information:
Directorio de Producción Científica
Scopus