“Contribution of Advection to
Primary Production in the Atlantic
Water Inflow into the Arctic Ocean”
Maria Vernet
Scripps Institution of Oceanography
with Ingrid Ellingsen, Dag Slagstad, Lena
Seuthe, Mattias R. Cape, Patricia A. Matrai
Phytoplankton Gross Primary Production
(g C m-2 6mo-1)
200
100
0
Atlantic Inflow into the Arctic Ocean
Fram
Strait
Iceland
Sea
(http://www. giss.nasa.gov/ research/briefs/ legrande_01).
Phytoplankton in
SINMOD model
Respiration
50 m
(SINTEF, Trondheim)
Biomass In
4 km
GPP
Excretion
Grazing
4 km
Biomass Out
Sinking
dBiomass / dt = Advection IN + Gross Primary Production Respiration – Excretion - Grazing - Sinking – Advection OUT
(mg C m-2 d-1)
Phytoplankton Model Variables
Advection: Biomass IN and Biomass OUT
In Situ:
– GPP, Gross Primary Production, uptake of CO2
– Respiration, loss of CO2
– Excretion, loss of Dissolved Organic Matter
– Sinking, cell sinking
– Grazing, consumption by zooplankton
Model Experiments along the Atlantic
Water Inflow
• Phytoplankton Properties
– Phytoplankton Growth
– Residence Time
– Phytoplankton Persistence
• Carbon Flux
– Contribution of Advection to local PP
• System Properties
– Exportable Carbon
1. Phytoplankton
Growth Rate
Biomass IN
Respiration
4 km
50 m
GPP
Excretion
Grazing
Sinking
(GPP – Respiration) / B
4 km
Biomass OUT
Experiment 1: Phytoplankton
Population Growth (d-1)
0.14
0.08
0
2. Residence
Time
Biomass IN
Respiration
4 km
50 m
GPP
Excretion
Grazing
Sinking
Biomass / Biomass IN
(relative to model grid size)
4 km
Biomass OUT
Experiment 2: Residence Time (d)
3. Persistence
Respiration
4 km
50 m
Biomass IN
GPP
Excretion
Grazing
Sinking
GPP = 0 at selected locations
4 km
Biomass OUT
Experiment 4: Persistence of
phytoplankton biomass (20%) along
the Atlantic Water Inflow
1 July
15 August
GPP = 0
Phytoplankton Persistence after PP=0
Experiment 4: Phytoplankton Carbon flux along the Atlantic
Water Inflow over the productive season (Tg C 6mo-1)
Secti Flux (Tg C ^6m-1)
on
A
2.31 (1.06)
0.97)
B
1.18 (0.07)
C
0.76 (0.19)
D
0.36
(BSO:
85% Decrease in
Carbon advection
from Northern
Norway (A) to NE
Northern Barents Sea
(D)
5. Contribution of
Advection to Primary
Production
Biomass In
Respiration
4 km
50 m
GPP
Excretion
Grazing
Sinking
Biomass IN / GPP
4 km
Biomass OUT
Experiment 5: Contribution of Phytoplankton
Advection to local Primary Production
50
25
0
6. Carbon balance
4 km
Respiration
50 m
Biomass IN
GPP
Excretion
Grazing
4 km
Biomass OUT
Sinking
Carbon Balance = Gross Primary Production
– Respiration – Excretion - Grazing – Sinking
= Net Flux = Biomass OUT – Biomass IN
Experiment 6: Carbon balance (g C m-2)
in growth season
+20
0
-20
NW Spitsbergen, 79°N 4°E
End of season: surplus of ~15 g C m-2
GPP
Grazing
Budget
March
June
Sept
Seasonal progression
Phytoplankton biomass (mg Chla m-2) in 50m
Zooplankton Biomass (g C m-2)
Conclusions
• Phytoplankton Properties
– Higher growth rates along the Atlantic Water
– Lower residence time in the Atlantic Inflow than
elsewhere
– Phytoplankton can stay in the current for 150-300
km
Conclusion: Phytoplankton Carbon fluxes
Advection of phytoplankton provides 20 - 50 times
more biomass than local production along the
Atlantic Water Inflow
From the Norwegian Sea to the Arctic
Ocean: Carbon Bridge
The model predicts import of phytoplankton biomass
into the West Spitsbergen Current from the
Norwegian Current and into the Arctic Ocean from
excess production west of Spitsbergen
Carbon imported into the Arctic Ocean
The model predicts import of phytoplankton biomass
into the Arctic Ocean at an annual rate of ~15 g C m-2
during springtime before the maximum in situ
production
Conclusion: Ecosystem Properties
On average (April to September),
the Norwegian Coastal Current is a top-down system
(net consumption);
the current West of Spitsbergen is a bottom-up
system (net production),
while the region North of Svalbard is balanced
What is the take-home message?
• The Atlantic Water Inflow affects
phytoplankton productivity by extending
carbon towards the north or into the Arctic
Ocean. The current is not homogeneous, with
a clear decrease in carbon flow from northern
Norway to northern Barents Sea. However the
carbon balance along the current shows
regional variability establishing net productive
and net consumption locations.
Thank you!
From R/V Helmer Hanssen, August 2014
Projections of changes in Gross Primary
Production as Arctic sea ice recedes (g C m-2 yr1)(IPCC-A1B climate scenario)
Slagstad et al. 2015
Primary Production in the Atlantic Water Inflow:
in situ vs advection
Slagstad et al. 2015
Phytoplankton Seasonal Carbon Flux
along the Atlantic Water Inflow
g C yr-1
West Spitsbergen Current
Barents Opening
SST anomaly at Fram Strait
Korablev et al. 2014
Bloom development north of Svalbard: May and August 2014
Reigstad et al., unpublished
Zooplankton Grazing (Calanus spp and Ciliates)
Why the abrupt system change as the Atlantic Inflow
enters the Arctic Ocean?
Projections of gross Primary Production as Arctic sea
ice recedes (g C m-2 yr-1)(IPCC-A1B climate scenario)
Slagstad et al. 2015