Transcript MARNAUT 2007

To assess microbial assemblages and microbiallydriven biogeochemical processes related to active
and past fluid seepage at cold seeps in the
Marmara Sea
To link biogeochemical processes and microbial
assemblages to fluid seepage patterns and
dynamics
More specifically we aim at :
Defining the structure, diversity and functionning of
microbial assemblages involved in the transformation
of fluid components (e.g., methane oxidation, sulphate
reduction, sulphide oxidation...)
Understanding how microbial assemblages (and
associated processes) respond to varying seepage
activity, compostion and chemistry of fluids, flow
rates... and how they impact on the precipitation of
authigenic minerals and on cold-seep macrofauna
Molecular Tools : lipid biomarkers
microbial cell membrane lipids as sources
information (biomarkers) on the composition
and biogeochemistry of microbial assemblages
Distinctive ‘taxonomic’ structural features > > community structure
Concentrations > > relative abundances of microbial groups
> > biomass of extant (active) organisms
Stable carbon isotopes > > carbon source utilized, carbon flow
OH
O
OX
X’
O
O
OH
X
Molecular Tools : lipid biomarkers
Lipid biomarkers : analytical methods
• Solvent extraction of lipids
• Chromatographic isolation of lipid biomarker classes
• Gas chromatography (GC)
• Gas chromatography-mass spectrometry (GC-MS)
• Isotope ratio monitoring-gas chromatography-mass spectrometry (GC-irMS) *
• High performance liquid chromatography- mass spectrometry (HPLC-MS) *
* in collaboration
Undisturbed Sediments Cores
Authigenic Crusts
Microbial Mats, Benthic Fauna
Samples to be taken in contrasted settings :
Varying fluid seepage
Different benthic activity
To be sub-sampled and conditionned on board
And to be shared for coupled investigations
This contribution to the MARNAUT project is viewed as
part of an integrated biogeochemical approach and, as
such, it requires strong interdisciplinary coupling
More specifically we plan to tightly couple this study with:
Microbiology and molecular biology approaches
(P. Lopez)
Fluid analyses and fluxes, biogeochemical
reaction rates, transport/reaction models (V. Aloisi)
Authigenic carbonate geochemistry (C. Pierre)
Biology of benthic fauna (Ifremer, Brest)
Previous and ongoing work at cold seeps in the framework of
MEDIFLUX (ESF)
BIOZAIRE (IFREMER/TOTAL)
HERMES (EU)
Biomarkers in Crusts
(Olimpi mud volcano area - MEDINAUT)
Apolar compounds
C25 isoprenoids
C20 isoprenoids
Cr
PMI:0
PMI:1-3
Squ:0
Cr:1
H
H
C25 isoprenoids
PMI:3-5
C30 isoprenoids
Squ: 3-6
C35 isoprenoids
Bouloubassi et al., (2006)
Biomarkers in Crusts
(Olimpi mud volcano area-MEDINAUT)
Polar compounds
OH
I
X
Archaeol
O
O
X’
O X
OH
O
IId
II
IIa
O
O X
IIc
OH
Hydroxyarchaeol
Ib IIb
Ic
Bouloubassi et al., (2006); Aloisi et al., 2002; Pancost et al., 2001
d13C ‰
Bouloubassi et al., (2006)
B
A
E
B
B
n-29 Alkane
cholesterol
BisHomo-ol
BisHomo-acid
ia15 FAME
ia17 FAME
Diethers II
Diethers I
PMI:1-5
PMI
DGDT
Archaeol
OH-Archaeol
Biomarkers in Crusts
(Olimpi & Anaximander mud volcano area)
NAUTINIL 2003
Polar lipid patterns in carbonate crusts
NL 20 CC1
Caldera
X
Archaeol
O
X’
O
Hydroxyarchaeol
OH
OH
O
NL 14 CC5
Pockmarks
Dialkyl Glycerol
Diethers (DGD)
O X
OH
O
O X
...and suite of sterols, alcohols, hopanols
hopanoïdes
crocetane
PMI
GC/MS : Fraction hydrocarbures
n-alcanes (C14 – C34) : essentiellement sources terrigènes
Hopanoïdes (hopanes-hopènes, C27 - C32 : sources microbiennes - Bactéries
C20 et C25 Isoprénoïdes irréguliers : sources microbiennes - Archées