drivers of biological o flux western antarctic...
TRANSCRIPT
• Motivating question
What are the biological and physical processes driving O2saturation and net community production variability at the Palmer LTER region?
Drivers of biological O2 fluxin the Western Antarctic Peninsula
grid station (km)
grid
line
(km
)
−200−1000100200−200
−100
0
100
200
300
400
500
600
700
800
Antarctic Peninsula
Slope
Coast
Shelf
Anvers Is.
Charcot Is.
Marguerite Bay
<350 m350-500 m500-650 m650-800 m
Depth
Sout
hern
AC
C
Alexander Is.
Adelaide Is.
GerlacheStrait
grid
line
(km
)
grid station (km)
>800 m
Renaud Is.
Biological O2 flux
Nutrients, EnergyPhysical processes
Taxonomy, PhysiologyBiological processes
Gas saturation at the Peninsula
Eveleth et al. (2014)
Argon (Ar) O2/ArPhysical O2 Biological O2
? ?
Physical O2
Biological O2
Supe
rsat
urat
ion
U
nder
satu
ratio
n
• Warming • Decreasing Atm
Pressure • Sea-ice Formation • Increasing Salinity • Bubble Processes • Mixing Different T
Water Masses 0%
• Cooling • Increasing Atm
Pressure • Sea-ice Melt • Decreasing
Salinity
+
-
2
• Photosynthesis
• Respiration • Upwelling of O2
undersaturated waters
2
Gas Exchange
Gas Exchange
NCP = Photosynthesis ‐ Respiration
−2000200−200
0
200
400
600
800
Total O2 Supersat %
−10 0 10 20
−2000200−200
0
200
400
600
800
Bio O2 Supersat %
−10 0 10 20
−2000200−200
0
200
400
600
800
Ar Supersat %
−5 0 5
Biological and Physical Oxygen (January 2012)
Δ(O2)total (%) Δ(O2/Ar) (%) Δ(Ar) (%)Biological O2 Physical O2Total O2 = +
Eveleth et al. (in prep.)
18O data from Mike Meredith (BAS)
grid station (km)
grid
line
(km
)
−2000200−200
0
200
400
600
800
Meteoric Water (%)
0 2 4
grid station (km)
−2000200−200
0
200
400
600
800
Sea Ice Meltwater (%)
−1 0 1 2
−2000200−200
0
200
400
600
800
Ar (%)
−5 0 5
grid station (km)
Eveleth et al. (in prep.)
grid station (km)
grid
line
(km
)
−200−1000100200−200
−100
0
100
200
300
400
500
600
700
800
Antarctic Peninsula
Slope
Coast
Shelf
Anvers Is.
Charcot Is.
Marguerite Bay
<350 m350-500 m500-650 m650-800 m
Depth
Sout
hern
AC
C
Alexander Is.
Adelaide Is.
Gerlache Strait
grid
line
(km
)
grid station (km)
>800 m
Renaud Is.
Offshore
Northern Onshore
Southern Onshore
grid station (km)
grid
line
(km
)
−200−1000100200−200
−100
0
100
200
300
400
500
600
700
800
Antarctic Peninsula
Slope
Coast
Shelf
Anvers Is.
Charcot Is.
Marguerite Bay
<350 m350-500 m500-650 m650-800 m
Depth
Sout
hern
AC
C
Alexander Is.
Adelaide Is.
GerlacheStrait
grid
line
(km
)
grid station (km)
>800 m
Renaud Is.
January NCP Grid Variability
350 km
grid
line
100 km grid station
Regional Mean NCP
Offshore N.Onshore S.Onshore−50
0
50
100
150
200
Mea
n N
CP(
mm
ol O
2 m−2
d−1
)
201220132014
(Note: No correction for vertical mixing at this time)
−2000200400600800−50
0
50
100
150
200
250
grid line (km)
NC
P(m
mol
O2 m
−2 d
−1)
2012
−2000200400600800−200
−100
0
100
200
300
400
grid line (km)
NC
P(m
mol
O2 m
−2 d
−1)
2013
−2000200400600800−200
0
200
400
600
800
grid line (km)
NC
P (m
mol
O2 m
−2 d
−1)
2014
N S N S N S
grid station (km)
grid
line
(km
)
−200−1000100200−200
−100
0
100
200
300
400
500
600
700
800
Antarctic Peninsula
Slope
Coast
Shelf
Anvers Is.
Charcot Is.
Marguerite Bay
<350 m350-500 m500-650 m650-800 m
DepthSo
uthe
rn A
CC
Alexander Is.
Adelaide Is.
GerlacheStrait
grid
line
(km
)
grid station (km)
>800 m
Renaud Is.
Annually‐integrated NCP (1997 – 2014)
Schoefield et al. 2013, Kavanaugh et al. 2015, in press Li & Cassar, in prep
Biological O
2flu
x (m
molm
‐2d‐
1 )
R² = 0.46
-5
5
15
25
35
45
55
0.2 0.3 0.4 0.5 0.6 0.7
ΔO2/Ar vs. Fv/Fm
All MLD <40m
Lin et al., in prep
Biological O
2
Fv/Fm (Iron sufficiency)0 10 20 30 40 50 60 70
0
50
100
150
200
250
MLD (m)
NC
P (m
mol
O2 m
−2 d
−1)
2012‐2014
Photo by Ed Delong
Biological O2 flux
Cracking the black box…
‐10
0
10
20
30
40
50
0%
20%
40%
60%
80%
100%
% of 1
8S re
ads Dino
Unclassified
HaptoCrypto
Centric diatomPennate diatom
O2/Ar
Cracking the black box…
Stations ranked in descending biological O2Lin et al., in prep.
Paleo‐proxy of NCP?
‐2
0
2
4
6
8
10
12
14
16
18
20
0%
20%
40%
60%
80%
100%
Diatom_C3_013
Diatom_C4_002
Diatom_C1_007
Diatom_C2_010
Diatom_B5_155
Diatom_B3_009
Diatom_B4_012
Diatom_B1_004
O2Ar/POC
Centric
Pennate
Stations ranked in descending O2/Ar/POC proxy
3 of 5 most dominant Diatom OTUs show strong correlation ~ NCP
Linear model ‐ stepwise regression:
NCP ~1.63 1 2.49 2 1.37 5
R² = 0.85P<0.0001
0
10
20
30
40
50
60
‐10 0 10 20 30 40 50
Mod
el (C
1,C2
,C5)
O2/Ar
Proboscia
Thalassiosira
Corethron
PennateF. cylindrus
Which Diatoms?
%
Autotrophs
Heterotrophs• Gamma• Unclassified• Flavo• Alpha• Beta
How interactions influence NCP?
NCP = Photosynthesis ‐ Respiration
Network Sphere
grid station (km)
grid
line
(km
)
−200−1000100200−200
−100
0
100
200
300
400
500
600
700
800
Antarctic Peninsula
Slope
Coast
Shelf
Anvers Is.
Charcot Is.
Marguerite Bay
<350 m350-500 m500-650 m650-800 m
Depth
Sout
hern
AC
C
Alexander Is.
Adelaide Is.
GerlacheStrait
grid
line
(km
)
grid station (km)
>800 m
Renaud Is.
Offshore
Northern Onshore
Southern Onshore
• Less spatially variable• Fe limitation
• Strong Ar undersaturation from melt
• High iron sufficiency• Ice may supply Fe and
lead to shallower MLDs?
• High iron sufficiency• Fe supply from upwelling?
Onshore hot spots co‐located with canyons
Preliminary Conclusions:
Eveleth et al. in prep.
One (biological/physical) solution does not fit all…
Snapshot view
Preliminary Conclusions
• Grid region: Biology dominates O2 saturation (strong anti‐correlation O2/Ar vs. pCO2)
• However, large physical Ar undersaturation at the ice edge in Grid (Drake: Physics dominates O2)
• NCP: Diatoms are not equal, not just Crypto vs. Diatoms
• Light vs. Fe modulating NCP (Grazing?)
• Role of canyons in NCP (field, satellite observations & penguin colonies)
• Winter priming is important, biological response varies
Questions?
Wish list: More winter measurementsIncreased joint use of biogeochemical & molecular toolsPhysical circulation in the canyonsRelation of NCP to carbon and other nutrients attenuation at depth