Interdecadal changes in intensity of the oxygen minimum zone off Concepción, Chile (~ 36° S), over the last century

Interdecadal changes in intensity of the oxygen minimum zone off Concepción, Chile (~ 36° S), over the last century

We reconstructed oxygenation changes in the upwelling ecosystem off Concepción (36° S), Chile, using inorganic and organic proxies in a sediment core covering the last ca. 110 years of sedimentation in this area. Authigenic enrichments of Mo, U and Cd were observed between ca. 1935 and 1971 CE, impl...

Full description

Saved in:
Bibliographic Details
Published in:Biogeosciences Vol. 12; no. 20; pp. 6045 - 6058
Main Authors: Srain, B, Pantoja, S, Sepúlveda, J, Lange, C B, Muñoz, P, Summons, R E, McKay, J, Salamanca, M
Format: Journal Article
Language:English
Published: Katlenburg-Lindau Copernicus GmbH 22-10-2015
Copernicus Publications
Subjects:
Algae
Anaerobic microorganisms
Aquatic ecosystems
Bacteria
Bioindicators
Biomarkers
Bottom water
Cadmium
Continental shelves
Coupling (molecular)
Deoxygenation
Depletion
Ecological monitoring
El Nino
Environmental changes
Frequency variation
Glycerol
Lipids
Metals
Microorganisms
Molybdenum
Ocean circulation
Oxidoreductions
Oxygen
Oxygen depletion
Oxygenation
Pacific Decadal Oscillation
Sedimentation
Sediments
Sterols
Upwelling
Water circulation
Water column
Chile
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We reconstructed oxygenation changes in the upwelling ecosystem off Concepción (36° S), Chile, using inorganic and organic proxies in a sediment core covering the last ca. 110 years of sedimentation in this area. Authigenic enrichments of Mo, U and Cd were observed between ca. 1935 and 1971 CE, implying a prolonged period with predominantly more reduced conditions in bottom waters and surface sediments. Significant positive correlations between redox-sensitive metals, algal sterols, biomarkers of micro-aerophilic and anaerobic microorganisms, and archaeal glycerol dialkyl glycerol tetraethers point to a tight coupling among bottom water O2 depletion and increased primary and export production. The time interval with low O2 of ca. 35 years seems to follow low-frequency interdecadal variation of the Pacific Decadal Oscillation, and it may have resulted in O2 depletion over the entire continental shelf off Concepción. Taking this together with the concurrent increase in sedimentary molecular indicators of micro-aerophilic and anaerobic microbes, we can suggest that changes in oxygenation of the water column are reflected by changes in microbial community. This study can inform our understanding of ecological consequences to projected trends in ocean deoxygenation.
ISSN:1726-4189
1726-4170
1726-4189
DOI:10.5194/bg-12-6045-2015