Lipid and 13C signatures of submicron and suspended particulate organic matter in the Eastern Tropical North Pacific

Implications for the contribution of Bacteria

Hilary Close, Stuart G. Wakeham, Ann Pearson

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The contribution of bacterial biomass to total particulate organic matter (POM) in the ocean, including exported material, is poorly constrained. To examine potential signatures for the presence and export of bacterioplankton and their detrital remains, here we provide a detailed compound-specific 13C characterization of fatty acids from membrane polar lipids obtained from a water column profile in the Eastern Tropical North Pacific. POM of submicron size (0.2-0.7μm; "X-POM") was sampled and analyzed separately from the size class typically collected as "suspended" POM (0.7-53μm; "L-POM"). The distributions of polar head group classes, specific fatty acid side chains, and natural 13C contents all vary, both between particle size classes and with depth in the water column. In general, the polar lipids in submicron material - and by inference, lipids of bacterial origin - have higher 13C content than polar lipids from larger POM and are equally abundant. Lipid signatures from the photic zone appear to be partially conserved in the suspended pool during transit down the water column. However, bacterial heterotrophy and possibly chemoautotrophy partially overprint these surface signatures. In addition, active metabolisms in the oxygen minimum zone (OMZ) appear to mediate the disaggregation of POM transported from the surface, thus adding complexity to the pathways of mid-water carbon flux and providing additional organic substrates to the OMZ and below. This "substrate injection" may provide important fuel for the denitrification and anammox reactions. Finally, examination of 13C content in polar lipids provides a basis for new interpretation of depth-related variations in δ13C values of bulk suspended POM.

Original languageEnglish (US)
Pages (from-to)15-34
Number of pages20
JournalDeep-Sea Research Part I: Oceanographic Research Papers
Volume85
DOIs
StatePublished - Mar 1 2014
Externally publishedYes

Fingerprint

particulate organic matter
lipid
bacterium
bacteria
lipids
water column
chemoautotrophy
fatty acid
water
fatty acids
heterotrophy
oxygen
substrate
photic zone
bacterioplankton
euphotic zone
carbon flux
denitrification
particle size
oceans

Keywords

  • Bacteria
  • Carbon isotopes
  • Eastern Tropical North Pacific
  • Lipid biomarkers
  • Oxygen minimum zone
  • Particulate organic matter

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

Cite this

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title = "Lipid and 13C signatures of submicron and suspended particulate organic matter in the Eastern Tropical North Pacific: Implications for the contribution of Bacteria",
abstract = "The contribution of bacterial biomass to total particulate organic matter (POM) in the ocean, including exported material, is poorly constrained. To examine potential signatures for the presence and export of bacterioplankton and their detrital remains, here we provide a detailed compound-specific 13C characterization of fatty acids from membrane polar lipids obtained from a water column profile in the Eastern Tropical North Pacific. POM of submicron size (0.2-0.7μm; {"}X-POM{"}) was sampled and analyzed separately from the size class typically collected as {"}suspended{"} POM (0.7-53μm; {"}L-POM{"}). The distributions of polar head group classes, specific fatty acid side chains, and natural 13C contents all vary, both between particle size classes and with depth in the water column. In general, the polar lipids in submicron material - and by inference, lipids of bacterial origin - have higher 13C content than polar lipids from larger POM and are equally abundant. Lipid signatures from the photic zone appear to be partially conserved in the suspended pool during transit down the water column. However, bacterial heterotrophy and possibly chemoautotrophy partially overprint these surface signatures. In addition, active metabolisms in the oxygen minimum zone (OMZ) appear to mediate the disaggregation of POM transported from the surface, thus adding complexity to the pathways of mid-water carbon flux and providing additional organic substrates to the OMZ and below. This {"}substrate injection{"} may provide important fuel for the denitrification and anammox reactions. Finally, examination of 13C content in polar lipids provides a basis for new interpretation of depth-related variations in δ13C values of bulk suspended POM.",
keywords = "Bacteria, Carbon isotopes, Eastern Tropical North Pacific, Lipid biomarkers, Oxygen minimum zone, Particulate organic matter",
author = "Hilary Close and Wakeham, {Stuart G.} and Ann Pearson",
year = "2014",
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doi = "10.1016/j.dsr.2013.11.005",
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TY - JOUR

T1 - Lipid and 13C signatures of submicron and suspended particulate organic matter in the Eastern Tropical North Pacific

T2 - Implications for the contribution of Bacteria

AU - Close, Hilary

AU - Wakeham, Stuart G.

AU - Pearson, Ann

PY - 2014/3/1

Y1 - 2014/3/1

N2 - The contribution of bacterial biomass to total particulate organic matter (POM) in the ocean, including exported material, is poorly constrained. To examine potential signatures for the presence and export of bacterioplankton and their detrital remains, here we provide a detailed compound-specific 13C characterization of fatty acids from membrane polar lipids obtained from a water column profile in the Eastern Tropical North Pacific. POM of submicron size (0.2-0.7μm; "X-POM") was sampled and analyzed separately from the size class typically collected as "suspended" POM (0.7-53μm; "L-POM"). The distributions of polar head group classes, specific fatty acid side chains, and natural 13C contents all vary, both between particle size classes and with depth in the water column. In general, the polar lipids in submicron material - and by inference, lipids of bacterial origin - have higher 13C content than polar lipids from larger POM and are equally abundant. Lipid signatures from the photic zone appear to be partially conserved in the suspended pool during transit down the water column. However, bacterial heterotrophy and possibly chemoautotrophy partially overprint these surface signatures. In addition, active metabolisms in the oxygen minimum zone (OMZ) appear to mediate the disaggregation of POM transported from the surface, thus adding complexity to the pathways of mid-water carbon flux and providing additional organic substrates to the OMZ and below. This "substrate injection" may provide important fuel for the denitrification and anammox reactions. Finally, examination of 13C content in polar lipids provides a basis for new interpretation of depth-related variations in δ13C values of bulk suspended POM.

AB - The contribution of bacterial biomass to total particulate organic matter (POM) in the ocean, including exported material, is poorly constrained. To examine potential signatures for the presence and export of bacterioplankton and their detrital remains, here we provide a detailed compound-specific 13C characterization of fatty acids from membrane polar lipids obtained from a water column profile in the Eastern Tropical North Pacific. POM of submicron size (0.2-0.7μm; "X-POM") was sampled and analyzed separately from the size class typically collected as "suspended" POM (0.7-53μm; "L-POM"). The distributions of polar head group classes, specific fatty acid side chains, and natural 13C contents all vary, both between particle size classes and with depth in the water column. In general, the polar lipids in submicron material - and by inference, lipids of bacterial origin - have higher 13C content than polar lipids from larger POM and are equally abundant. Lipid signatures from the photic zone appear to be partially conserved in the suspended pool during transit down the water column. However, bacterial heterotrophy and possibly chemoautotrophy partially overprint these surface signatures. In addition, active metabolisms in the oxygen minimum zone (OMZ) appear to mediate the disaggregation of POM transported from the surface, thus adding complexity to the pathways of mid-water carbon flux and providing additional organic substrates to the OMZ and below. This "substrate injection" may provide important fuel for the denitrification and anammox reactions. Finally, examination of 13C content in polar lipids provides a basis for new interpretation of depth-related variations in δ13C values of bulk suspended POM.

KW - Bacteria

KW - Carbon isotopes

KW - Eastern Tropical North Pacific

KW - Lipid biomarkers

KW - Oxygen minimum zone

KW - Particulate organic matter

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U2 - 10.1016/j.dsr.2013.11.005

DO - 10.1016/j.dsr.2013.11.005

M3 - Article

VL - 85

SP - 15

EP - 34

JO - Deep-Sea Research Part I: Oceanographic Research Papers

JF - Deep-Sea Research Part I: Oceanographic Research Papers

SN - 0967-0637

ER -