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

B. Srain; S. Pantoja; J. Sepúlveda; C. B. Lange; P. Muñoz; R. E. Summons; J. McKay; M. Salamanca

doi:10.5194/bg-12-6045-2015

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

B. Srain, S. Pantoja^*, J. Sepúlveda, C. B. Lange, P. Muñoz, R. E. Summons, J. McKay, M. Salamanca

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

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.

Original language	English
Pages (from-to)	6045-6058
Number of pages	14
Journal	Biogeosciences
Volume	12
Issue number	20
DOIs	https://doi.org/10.5194/bg-12-6045-2015
Publication status	Published - 22 Oct 2015
Externally published	Yes

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Copyright the Author(s) 2015. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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10.5194/bg-12-6045-2015

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title = "Interdecadal changes in intensity of the oxygen minimum zone off Concepci{\'o}n, Chile (∼ 36° S), over the last century",

abstract = "We reconstructed oxygenation changes in the upwelling ecosystem off Concepci{\'o}n (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 Concepci{\'o}n. 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.",

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AU - Lange, C. B.

AU - Muñoz, P.

AU - Summons, R. E.

AU - McKay, J.

AU - Salamanca, M.

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PY - 2015/10/22

Y1 - 2015/10/22

N2 - 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.

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

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