Ecological vectors of carbon and biomineral export in the Southern Ocean
Mathieu Rembauville Supervized by Ian Salter and St´ephane Blain 20th September 2016 - Banyuls-sur-mer
Introduction - oceanic carbon pumps
Slow carbon cycle Million yr CO2
Carbonate rocks
Carbon fluxes from Le Qu´ er´ e et al. (2015)
1
Introduction - oceanic carbon pumps FastAcarbonAcycleA Century -GtACAyr-1) AtmosphericAgrowth
4.4AAA0.1
SlowAcarbonAcycle Million yr
LandAsink
3.0AAA0.8
Anthropogenic emissions
9.9AAA1 LandAuseA change
FossilAfuels, Aindustry
0.9AAA0.5
9.0AAA0.5
Ocean sink
CO2
2.6AAA0.5
Carbonate rocks
Carbon fluxes from Le Qu´ er´ e et al. (2015)
1
Introduction - oceanic carbon pumps Atmosphere
Timescale
CO2
CO2 DIC
1 yr
e Int
MLD
r ate ew iat n ed tio rm rma fo
10 yr
DIC ter wa n ep tio De rma fo
1000 m
100 yr > 1000 yr
DIC Seafloor
Geological Solubility pump
2
Introduction - oceanic carbon pumps Atmosphere
Timescale
CO2 Photosynthesis CO2 DIC
1 yr
r ate e+w iat n ed tio rm rma fo
Sinking+++active+transport+
e Int
MLD
POC Respiration
DIC r ate +w n ep tio De rma fo
1000+m
DIC Seafloor
100 yr > 1000 yr
POC Fossil+fuels
Solubility pump
10 yr
Geological
Soft tissue pump
2
Introduction - oceanic carbon pumps Atmosphere
Timescale
CO2 Photosynthesis CO2
r ate egw iat n ed tio rm rma fo
RDOC
+
LDOC
r ate gw n ep tio De rma fo
DIC Seafloor
POC Fossilgfuels
Solubility pump
Soft tissue pump
1 yr 10 yr
RDOC r ate gw n ep tio De rma fo
DIC 1000gm
+
Sinkingg+gactivegtransportg
e Int
MLD
POC Respiration
ter wa teg dia tion me a er form Int
DIC
100 yr > 1000 yr
RDOC Geological Microbial carbon pump
2
Introduction - oceanic carbon pumps Atmosphere
Photosynthesis
Precipitation 2HCO3-g+gCa2+
CaCO3g+gH2Og+ CO2
Dissolution
POC
r ate egw iat n ed tio rm rma fo
DIC
Carbonategrocks Carbonate pump
+
LDOC
POC Fossilgfuels
Solubility pump
Soft tissue pump
1 yr 10 yr
RDOC r ate gw n ep tio De rma fo
DIC r ate gw n ep tio De rma fo
PIC
RDOC
Sinkingg+gactivegtransportg
e Int
Sinking
1000gm
+
Respiration ter wa teg dia tion me a er form Int
DIC
PIC
MLD
Seafloor
Timescale
CO2
100 yr > 1000 yr
RDOC Geological Microbial carbon pump
2
Introduction - oceanic carbon pumps Atmosphere
Photosynthesis
Precipitation 2HCO3-g+gCa2+
CaCO3g+gH2Og+ CO2
Dissolution
POC
r ate egw iat n ed tio rm rma fo
DIC
Carbonategrocks Carbonate pump
+
LDOC
POC Fossilgfuels
Solubility pump
Soft tissue pump
1 yr 10 yr
RDOC r ate gw n ep tio De rma fo
DIC r ate gw n ep tio De rma fo
PIC
RDOC
Sinkingg+gactivegtransportg
e Int
Sinking
1000gm
+
Respiration ter wa teg dia tion me a er form Int
DIC
PIC
MLD
Seafloor
Timescale
CO2
100 yr > 1000 yr
RDOC Geological Microbial carbon pump
2
an
S
d G olu rub bi er, lity 20 + C 06 c Lé ar - L irc vy bo év ul et n y e at al. at ,2 e t a io 01 co l., n 20 3- u Le M 13 n M ge i illim te nd cr r an -p re ob et ia et um al. l al. p , 2 ca ,1 01 r 99 5 - bo 6 He ns L n é on vy pu et B et m al. io al. p , 2 lo ,2 01 g 01 2 - ic 3 La al ws pu et m al. p ,2 01 1
ien to
rm
Sa
Mixed layer carbon flux (Gt yr-1 )
Sink
15 10 5 0 5 10 15 Source
Introduction - oceanic carbon pumps Mixed layer MLD
Deep ocean
3
an
S
d G olu rub bi er, lity 20 + C 06 c Lé ar - L irc vy bo év ul et n y e at al. at ,2 e t a io 01 co l., n 20 3- u Le M 13 n M ge i illim te nd cr r an -p re ob et ia et um al. l al. p , 2 ca ,1 01 r 99 5 - bo 6 He ns L n é on vy pu et B et m al. io al. p , 2 lo ,2 01 g 01 2 - ic 3 La al ws pu et m al. p ,2 01 1
ien to
rm
Sa
Mixed layer carbon flux (Gt yr-1 )
Sink
15 10 5 0 5 10 15 Source
Introduction - oceanic carbon pumps Mixed layer MLD
Deep ocean
3
Introduction - biological pump
Legendre and Lef` evre (1989)
4
Introduction - biological pump
Legendre and Lef` evre (1989)
Ecosystem structure driving the [biological pump] process remains largely uncharacterized. - Guidi et al. (2016) 4
Introduction - export in the Southern Ocean
BP efficiency from NO3– field
5
Introduction - export in the Southern Ocean Westerlies
Katabatic
winds
PF
SAF
STF
BSi : PON Si(OH)4
: NO3-
Continental shelf
MidoceanOridge
Si(OH)4 : NO3-
ANTARCTICA
HighOlatitude
LowOlatitude
Redrawn from Marshall and Speer (2000) 5
Introduction - export in the Southern Ocean 0° 30°E
30°W
60°W
60°E
90°W
90°E
120°W
120°E
150°W
Sediment trap data POC/BSi/PIC Diatom Fecal pellets Foraminifers Pteropods Coccolithophores
150°E 180°
Hydrological fronts STF SAF PF
6
Introduction - export in the Southern Ocean
60°W
60°E
a
1.5
POC flux (mol m-2 yr-1 )
30°E
16
a
a
1.0
ab
12 8
b
Primary production (mol m-2 yr-1 )
2.0
0° 30°W
0.5
4
0.0
0
b 16 90°E
b
12 BSi:POC
90°W
8
a
4 0
120°E
150°W
Sediment trap data POC/BSi/PIC Diatom Fecal pellets Foraminifers Pteropods Coccolithophores
150°E 180°
Hydrological fronts STF SAF PF
2.0 PIC:POC
120°W
1.5
a
a c a
b
1.0 0.5 0.0
SAZ (n=9)
PFZ (n=16)
c
c
POOZ (n=16)
SIZ (n=47)
PP values from Moore and Abbott (2000)
6
Introduction - Objectives
How plankton export assemblage regulates : I - the magnitude and seasonality of POC export ? II - the BSi:POC and PIC:POC stoichiometry of export ? III - the lipid composition of export ?
7
Introduction - Objectives
80°W 30°S
60°W
40°W
20°W
0°
20°E
40°E
60°E
80°E
1.4
40°S
Kerguelen
South Georgia PFZ
50°S
1.0 0.8
SAZ
0.6
AAZ
0.4
Chl ( g L-1 )
1.2
Crozet
0.2 0.0
60°S
M5
P3
KERFIX
A3
P2 M6
8
Introduction - Objectives
9
I - Magnitude and seasonality of POC export
I - Magnitude and seasonality of POC export
Rembauville et al., Biogeosciences, 2015 KEOPS2 - 290 m - October 2011 to September 2012 10
I - Magnitude and seasonality of POC export Imaging
Measurement
b
Specific.conversion
C.=.0.582.V0.811
a
a
C.=.0.039.V
b
a
b
C.=.0.036.V b
Diversity
a
Biovolume
Partitioned .POC.flux 11
POC flux (mmol m−2 d−1)
1.6
a)
CRS TRS Other diatoms Spherical faecal pellet Ovoid faecal pellet Cylindrical faecal pellet Ellipsoid faecal pellet Tabular faecal pellet
1.4 1.2 1 0.8 0.6 0.4 0.2 0
Oct
Nov 2011
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Calculated POC flux (mmol m−2 d−1)
I - Magnitude and seasonality of POC export 2.5
b)
2 ρ = 0.84 p < 0.001 r² = 0.72
1.5
1
0.5
0
2012
0
0.5
1
1.5
Measured POC flux (mmol m−2 d−1)
Rembauville et al., Biogeosciences, 2015
12
POC flux (mmol m−2 d−1)
1.6
a)
CRS TRS Other diatoms Spherical faecal pellet Ovoid faecal pellet Cylindrical faecal pellet Ellipsoid faecal pellet Tabular faecal pellet
1.4 1.2 1 0.8 0.6 0.4 0.2 0
Oct
Nov 2011
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Calculated POC flux (mmol m−2 d−1)
I - Magnitude and seasonality of POC export 2.5
b)
2 ρ = 0.84 p < 0.001 r² = 0.72
1.5
1
0.5
0
2012
0
0.5
1
1.5
Measured POC flux (mmol m−2 d−1)
Rembauville et al., Biogeosciences, 2015
12
I - Magnitude and seasonality of POC export
Auxospore (largest size) Vegetative cycle
Size reduction Sexual cycle
2n
2n Meiosis Zygote
n Gametes Fertilization
13
I - Magnitude and seasonality of POC export SporeRgermination (temperature,Rlight,Rdaylength) Auxospore (largestRsize) SporeRformation (nutrient,R lightRlimitation)
Mitosis
Vegetative cycle
SizeR reduction Resting cycle
Sexual cycle
2n
Physical, biological transport
MLD
2n Meiosis Zygote
n
RestingRspore
Gametes Fertilization
Seafloor
13
I - Magnitude and seasonality of POC export
Sediment CRS rel. ab. 50 % Spore dominant in sed. trap
Sediment data from Crosta et al. (1997) 14
I - Magnitude and seasonality of POC export
Sediment CRS rel. ab. 50 % Spore dominant in sed. trap
Rembauville et al., Deep Sea Research, 2016 Sediment data from Crosta et al. (1997) 14
II - BSi:POC and PIC:POC stoichiometry
II - BSi:POC and PIC:POC stoichiometry
Smetacek (1999)
F. kerguelensis Silica sinker BSi:POC
Wim van Egmond
Chaetoceros debilis Carbon sinker BSi:POC
15
II - BSi:POC and PIC:POC stoichiometry
Smetacek (1999)
Wim van Egmond
F. kerguelensis Silica sinker BSi:POC
Chaetoceros debilis Carbon sinker BSi:POC
How to link diversity with stoichiometry ?
15
II - BSi:POC and PIC:POC stoichiometry Micropal
Biological
16
II - BSi:POC and PIC:POC stoichiometry Biological technique: enumeration of full/empty cells
17
II - BSi:POC and PIC:POC stoichiometry Biological technique: enumeration of full/empty cells
Full > Empty
102
Empty > Full
Relative abundance (%)
CRS
101
F. kerguelensis
F. separanda/rhombica T. nitzschioides
Pseudo-nitzschia spp.
10
TRS
0
E. antarctica
T. lentiginosa
N. directa Thrix. antarctica
10-1
10-2
10-1
100 Empty:Full
101
102 17
II - BSi:POC and PIC:POC stoichiometry Micropaleontological technique: statistical relationship
18
II - BSi:POC and PIC:POC stoichiometry relationship a Micropaleontological technique: statistical b Fragilariopsis rhombica Fragilariopsis kerguelensis Thalassiosira gracilis Navicula directa Thalassionema nitzschioides Dactyliosolen antarcticus Pseudo-nitzshia heimii Pseudo-nitzchia lineola Thalassiosira oestrupii Chaetoceros (resting spore) Chaetoceros socialis 0.5 0.4 0.3 0.2 0.1 0.0 Bray-Curtis Distance
0.4
0.2 0.0 0.2 0.4 (BSi :POC)
0.6
Rembauville et al. (submitted) 18
II - BSi:POC and PIC:POC stoichiometry Silica vs. carbon sinker: validated with fluxes data ?
19
II - BSi:POC and PIC:POC stoichiometry Silica vs. carbon sinker: validated with fluxes data ?
19
II - BSi:POC and PIC:POC stoichiometry
2HCO3– + Ca2+ ←→ CaCO3 (PIC) + H2 O + CO2
20
II - BSi:POC and PIC:POC stoichiometry
2HCO3– + Ca2+ ←→ CaCO3 (PIC) + H2 O + CO2
CCpump =
CO2 ↑ PIC ↓ ∝ POC ↓ POC ↓
20
II - BSi:POC and PIC:POC stoichiometry
1/8th0wet0aliquot
Freeze-dried residue0 3700 m) Lins et al. (2015)
27
Conclusions
Conclusions I - Magnitude and seasonality of POC export • low POC flux in +Fe (
