Bess Ward
Department of Geosciences
Princeton University
Palmer Peninsula
Weddell Sea
Ross Sea
Pine Island Glacier breaks away from the Palmer
Peninsula -- global warming at work?
Cooling Trend in Antarctica -- warmer in polar seas
Doran et al., 2002
Doran et al., 2002
Palmer Peninsula
Weddell Sea
Ross Sea
Doran et al., 2002
Doran et al., 2002
Antarctic Continental Cooling
 Climate
indicators
Reduced
T, decreased wind, increased
sunshine
Reduced river flow, thicker ice
 Ecosystem
Less
effects
primary production
Fewer nematodes
Conflicting Signals of Climate
Change in Antarctica
 Indications
of global scale change?
 Feedback effects of global climate?
 Ecological consequences?
The Mystery of the Dysfunctional
Nitrogen Cycle
South Pole
Taylor Glacier
West LB
East Lake Bonney
One lake, two lobes connected at the surface
East Lake Bonney
West Lake Bonney
STRANGE…
NORMAL
N cycle non functional:
Way too much nitrous
oxide (N2O) and nitrate
(NO3)
N cycle functional:
Very little nitrous oxide
(N2O) and nitrate (NO3)
West LB
East Lake Bonney
WHY????
Nitrous oxide (N2O):
intermediate in denitrification
UV radiation
N2O involved in
Catalytic ozone
destruction
Ozone layer
N2
N2O = Greenhouse gas
bacteria
NO3
Nitrogen Concentrations (µM)
West Lobe
ammonium
East Lobe
ammonium
nitrate
nitrate
NORMAL
STRANGE
Nitrogen Concentrations (µM)
East Lobe
ammonium
nitrate
STRANGE
Nitrogen Concentrations (µM)
East Lobe
ammonium
East Lobe
nitrous oxide
nitrate
(Priscu et al., 1996; LTER)
STRANGE
REALLY STRANGE
First, drill a hole….
Weather port, West Lobe Lake Bonney
Sampling Hole through the Ice Cover
“Lab” inside the weather port
Isolate
denitrifying
bacteria and
detect them
in the lake
Speciesspecific
immunofluorescence
Distribution of strain
ELB17 (Marinobacter)
in Lake Bonney
(counted by
immunofluorescence)
East Lobe
Optimal
growth
conditions
for strain
ELB17
Nitrite reductase (nirS) genes in
Lake Bonney
 Central
enzyme in
denitrificaiton
encoded by nirS
 nirS genes found in
both lobes
Pa ra co ccu s p a n to tro p h u s
Pa ra co ccu s d e n itrifica n s
R o se o b a cte rd e n itrifica n s
100
N o g a le sAJ4 4 0 4 7 6
N o g a le sAJ4 4 0 4 8 3
100
5%
91
95
100
84
88
90
100
R a lsto n ia e u tro p h a
N o g a le sAJ4 4 0 4 9 2
N o g a le sAJ4 4 0 4 8 7
Alca lig e n e s fa e ca lis
Pse u d o mo n a s stu tze ri 1 4 4 0 5
Pse u d o mo n a s stu tze ri JM3 0 0
Pse u d o mo n a s flu o re sce n s
Pse u d o mo n a s a e ru g in o sa
[WL B1 6 -2 4]
1 0 0 N o g a le sAJ4 4 0 4 6 9
N o g a le sAJ4 4 0 4 7 8
N o g a le sAJ4 4 0 4 7 1
N o g a le sAJ4 4 0 4 7 3
N o g a le sAJ4 4 0 4 8 0
N o g a le sAJ4 4 0 4 8 6
N o g a le sAJ4 4 0 4 7 5
N o g a le sAJ4 4 0 4 8 9
100
N o g a le sAJ4 4 0 4 7 0
Bra ke r p A1 2
Bra ke r p B6 6
Bra ke r p A4
Bra ke r p B4 6
78
Bra ke r p C 5 6
100
Bra ke r p A9 0
85
Bra ke r p A2 9
Bra ke r p B7 6
Bra ke r p A3 2
Bra ke r p A2 5
Bra ke r p A9 8
Bra ke r p A9 4
1 0 0 Bra ke r p B4
62
Bra ke r p B4 9
Bra ke r p A5 0
Bra ke r p B2 0
[WL B1 6 -2 9]
Bra ke r p A5
Bra ke r w F1 6
62
70
77
72
Bra ke r w A1 5
N o g a le sAJ4 4 0 4 7 7
1 0 0 [EL B1 6 -2 0]
[EL B1 6 -3 5]
[EL B1 9 -2 0]
[EL B1 9 -1]
[EL B1 9 -2 8]
[EL B1 9 -3]
[EL B1 6 -3 0]
[EL B1 6 -3 3]
[EL B1 6 -4 0]
[EL B1 9 -3 8]
[EL B1 6 -1 6]
[EL B1 9 -2 4]
[EL B1 9 -6]
[EL B1 9 -3 6]
[EL B1 9 -3 0]
[EL B1 6 -3 2]
[EL B1 6 -2 4]
[EL B1 9 -1 6]
[EL B1 9 -4 0]
[EL B1 9 -2 5]
[EL B1 6 -2 5]
[EL B1 6 -9]
[EL B1 9 -1 1]
[EL B1 6 -4]
[EL B1 9 -1 4]
[EL B1 9 -1 5]
[EL B1 6 -7]
[EL B1 6 -2 8]
[EL B1 6 -2 7]
[EL B1 6 -2 6]
[EL B1 6 -5]
[EL B1 9 -3 3]
[EL B1 9 -8]
[EL B1 9 -4]
[EL B1 9 -1 7]
[EL B1 9 -3 5]
[EL B1 6 -3 6]
[EL B1 6 -3 1]
[EL B1 9 -3 2]
[EL B1 9 -2 6]
[EL B1 9 -3 9]
[EL B1 6 -3 9]
[EL B1 6 -6]
[EL B1 9 -1 8]
[EL B1 9 -5]
[EL B1 6 -3 4]
[EL B1 6 -3 8]
[EL B1 6 -1 1]
[EL B1 6 -1]
[EL B1 9 -4 2]
86
66
H a lo mo n a s va ria b lis B9 -1 2
[EL B2 5 -5]
Ma rin o b a cte r sp . C 1 0 -1
Ma rin o b a cte r sp . D 4 -1 4
[WL B1 6 -4]
[WL B1 6 -9 4]
[WL B1 6 -5 8]
[WL B1 6 -5]
[WL B1 6 -3 5]
[WL B1 6 -5 3]
7 2 [EL B2 5 -4 3]
[WL B1 6 -5 1]
[WL B1 6 -7 4]
[WL B1 6 -9 0]
[WL B1 6 -9 3]
[WL B1 6 -3 0]
[WL B1 6 -4 0]
[WL B1 6 -4 7]
1 0 0 [EL B2 5 -7]
[EL B2 5 -7 5]
[EL B2 5 -1 9]
[EL B2 5 -1 4]
[EL B2 5 -5 5]
75
[EL B2 5 -9]
64 [WL B1 6 -1 0]
93
[WL B1 6 -8 9]
[EL B2 5 -5 6]
[EL B2 5 -5 0]
[WL B1 6 -7]
[WL B1 6 -1]
[EL B2 5 -7 8]
[WL B1 6 -1 6]
[WL B1 6 -8 2]
[WL B1 6 -7 3]
[EL B2 5 -3 1]
[WL B1 6 -7 0]
[EL B2 5 -5 9]
90
[EL B2 5 -2 3]
[EL B2 5 -4 1]
[EL B2 5 -2 7]
[EL B2 5 -3 9]
[EL B2 5 -3]
[EL B2 5 -2]
[EL B2 5 -5 2]
[EL B2 5 -7 6]
[EL B2 5 -1 1]
[EL B2 5 -6 2]
[EL B2 5 -7 4]
[EL B2 5 -1 8]
[EL B2 5 -5 7]
[EL B2 5 -7 9]
[EL B2 5 -1 0]
[EL B2 5 -1 3]
[EL B2 5 -8 4]
6 3 [EL B2 5 -3 4]
62
95
99
99
96
Chris Francis
Sharon Harris:
Teacher
Experiencing
Antarctica
Measuring denitrification
rates based on N2O
production
Denitrification rate
Depth (m)
West Lobe
Denitrification
N2 O (nM/h)rate
-5
0
5
10
15
20
0
Depth (m)
5
10
15
20
25
30
East Lobe
Denitrification does not occur
in the East Lobe…but all the
ingredients are present

Denitrifiers can be isolated from the lake
The strains survive under in situ conditions
Denitrifying cells are detected in the lake
Denitrifying genes are detected in the lake
Denitrification happens in the bags, not in the lake

So what is the #?@@*#&^&*$ problem??




Nitrogen Concentrations (µM)
East Lobe
ammonium
East Lobe
nitrous oxide
nitrate
(Priscu et al., 1996; LTER)
STRANGE
REALLY STRANGE
East
Mark Wells
West
Copper low
hi
Silver
low
hi
Nitrite Reductase, Nitrous Oxide Reductase
(Cu, heme)
NO3
NO2
NO
(Cu)
N2O
Inducible, conserved, gas metabolism
N2
The Copper Hypothesis
 Cu
is required for denitrification
 Ag substitutes for Cu in denitrification
enzymes, and makes them nonfunctional
 Ag toxicity or competition with Cu inhibits
denitrification in the East
 But how did the two lobes end up with such
different Ag / Cu ratios?
Taylor Glacier
West Lobe
East Lobe
LTER
Blood Falls, West Lake Bonney
Blood Falls, West Lake Bonney
Taylor Glacier
W
E
Cross section of Lake Bonney today
Taylor Glacier
W
Lake Bonney 3000 years ago
“cold-dry” period
E
Taylor Glacier
W
E
Taylor Glacier
W
E
Taylor Glacier
W
E
Taylor Glacier
W
E
Taylor Glacier
W
Lake Bonney 1200 years ago
Hypersaline pool in the East Lobe
E
Taylor Glacier
W
E
Taylor Glacier
W
E
Taylor Glacier
W
E
Cross section of Lake Bonney today
Geochemical Evidence
 West
and East Lobes have different
histories
 History reflected in chemical composition
of the water
 Modern biogeochemistry depends on past
climate change
 Future climate change depends on current
biogeochemistry
Bonney Hoppers
Sunrise at McMurdo, 11 July 2001