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Phytoplankton in a high-COPhytoplankton in a high-CO22 world: world:
biological responses and their biological responses and their
biogeochemical implicationsbiogeochemical implications
Ulf Riebesell
Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR) Kiel University, Germany
Potential drivers in a high-COPotential drivers in a high-CO22 world world
Atmospheric COAtmospheric CO22
Mixing,Mixing,stratificationstratification
CirculationCirculation
LightLight NutrientsNutrients
Carbon sinks & sourcesCarbon sinks & sources
Oceanic COOceanic CO22
CarbonateCarbonatechemistrychemistry
Global warmingGlobal warming
Surface ocean Surface ocean temperaturetemperature
Nutrient utilizationNutrient utilizationefficiencyefficiency
AtmosphericAtmosphericdust dust (Fe)(Fe)
PrecipitationPrecipitation
Ocean biotaOcean biota
WindWindstressstress
Rain ratioRain ratio(CaCO(CaCO33/C/Corgorg))
StoichiometryStoichiometry(Si/C/N/P/Fe)(Si/C/N/P/Fe)
Criteria for evaluatingCriteria for evaluatingthe biogeochemical relevance of feedbacksthe biogeochemical relevance of feedbacks
Sign of changeSign of changepositive feedback positive feedback amplifies initial perturbationamplifies initial perturbationnegative feedbacknegative feedback dampens initial perturbationdampens initial perturbation
SensitivitySensitivitylevel of perturbation needed to trigger a feedbacklevel of perturbation needed to trigger a feedback
CapacityCapacitystrength of feedback compared to initial perturbationstrength of feedback compared to initial perturbation
LongevityLongevityrelevant time-scales: permanent vs. transientrelevant time-scales: permanent vs. transient
Today‘s worldToday‘s worldpCOpCO22: 280-380 ppmV: 280-380 ppmV
High-COHigh-CO22 world worldpCOpCO22: 580-720 ppmV: 580-720 ppmV
Emiliania huxleyiEmiliania huxleyi
Gephyrocapsa Gephyrocapsa oceanicaoceanica
Calcidiscus leptoporusCalcidiscus leptoporus
CO2-Calcification feedback
0
50
100
150
200
250
300
350
400
0 200 400 600 800 1000
Calc
ite c
onte
nt
(pg p
er
cell)
ppCOCO22 (µatm) (µatm)
Coccolithus pelagicusCoccolithus pelagicus
BUT !BUT !
CO2-Calcification feedback
10m
S=31.3S=29.8
S=31.3
Sediment Trap
pump
COCO22 regulation regulation
95% PAR95% PAR• 190 ppmV• 370 ppmV• 700 ppmV
190190370370
700700
pCOpCO22 (ppmv)(ppmv)
Large Scale Facilities, Bergen, NorwayLarge Scale Facilities, Bergen, Norway
Plankton development under Plankton development under
past, present and future COpast, present and future CO22
(Mesocosm experiments in 2000 and 2003)(Mesocosm experiments in 2000 and 2003)
5m
pCO2 normalised
0 5 10 15 200
200
400
600
800
Day
µatm
0
2
4
6
8
10
12
14
0 5 10 15 20
Chlorophyll a
pCO2 (normalized)ppm
Vµ
g L
-1Year 2100PresentLGM
Mesocosm experimentMesocosm experimentBergen 2000Bergen 2000
Emiliania huxleyiEmiliania huxleyi
Initial nutrient concentrations:Initial nutrient concentrations: NONO33
-- 15.5 mmol m 15.5 mmol m-3-3
POPO443-3- 0.51 mmol m 0.51 mmol m-3-3
Si(OH)Si(OH)44 ~0 ~0
NONO33-- and PO and PO44
3-3- exhausted on day 13 exhausted on day 13
B. Delille et al., in prep.B. Delille et al., in prep.
Primary production and calcification during a bloom of Primary production and calcification during a bloom of Emiliania huxleyiEmiliania huxleyi
Calcification
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)Production
Dissolution
Respiration -10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d2
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d4d3
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)d10
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d11
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d12
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d13
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
) d14
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
) d15
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)d18
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d21-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d21-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d21-10
10
20
30
(µmolC.kg-1.d-1)
(µm
olC
.kg-1
.d-1
)
d23
B. Delille et al. in prep.B. Delille et al. in prep.
CO2-Calcification feedback
10 20 30
-10
10
20
30
d11
d13
d15
d17
d2
d7
d23
(µm
olC
.kg-1
.d-1
)
d11
d13
d15
d17
d23
d2
d7
d11
d13
d15d17
d23
d7
d2
d11
d13
d15
d17d2
d7
d23
d11
d13
d15
d7
d23
d2
10 20 30-5
-10
10
20
30
d11
d13
d15 d17
d23
d7
(µmolC.kg-1.d-1)
10 20 30-5
d7
d11
d13
d15
d23
(µmolC.kg-1.d-1)
10 20 30-5
d11
d13
d15d17
d2
d7
d23
(µmolC.kg-1.d-1)
Year 2100(700 ppmV)
Present(370 ppmV)
LGM(190 ppmV)
Calcification
Pro
du
cti
on
Resp
ir.
Dissol.
-10
10
20
30
d11
d13 d15
d17
d19
d21
d2
d9
(µm
olC
.kg-1
.d-1
)(µ
mol
C.k
g-1.
d-1)
B. Delille et al. in prep.B. Delille et al. in prep.
-10
10
20
30
d11
d13
d15
d17
d2
d7
d23
(µm
olC
.kg-1
.d-1
)
10 20 30-5
-10
10
20
30
d11
d13
d15 d17
d23
d7
(µmolC.kg-1.d-1)
Year 2100(700 ppmV)
Present(370 ppmV)
LGM(190 ppmV)
Calcification
Pro
du
cti
on
Resp
ir.
Dissol.
-10
10
20
30
d11
d13 d15
d17
d19
d21
d2
d9
(µm
olC
.kg-1
.d-1
)(µ
mol
C.k
g-1.
d-1)
B. Delille et al. in prep.B. Delille et al. in prep.
Increasing pCOIncreasing pCO22 from from
190 ppmV to 700 ppmV caused190 ppmV to 700 ppmV caused
24-48 h delay in the 24-48 h delay in the onset of calcificationonset of calcification
40% decrease in 40% decrease in CaCOCaCO33 production production
Atmospheric COAtmospheric CO22
EcosystemEcosystem
pH, pH, Ca COCa CO33
Rain ratioRain ratio
Bio-Bio-calcificationcalcification
FunctionalFunctionalgroupsgroups
EnvironmentEnvironment
BiogeochemistryBiogeochemistry
Surface ocean alkalinitySurface ocean alkalinity
Loop with Loop with eveneven number of negative influences: number of negative influences: positive feedbackpositive feedback oddodd number of negative influences: number of negative influences: negative feedbacknegative feedback
CO2-Calcification feedback
negative influencepositive influence Sign of change
negative feedback (dampens initial perturbation)
Sensitivity high
Capacity low (6-30 Gt C until 2100
for 20-40% decrease)
Longevity permanent vs. transient ?
pCO2 (ppmV)
100
200
300
400
500
600
700
00 02 04 06 08 10 12 14 16 18day
Chlorophyll a
ppm
Vµ
g L
-1
0
1
2
3
4
5
1 3 5 7 9 11 13 15 17 19 21
Year 2100PresentLGM
pCO2 (normalized)
Chlorophyll a
Initial nutrient concentrations:Initial nutrient concentrations: NONO33
-- 8.0 mmol m 8.0 mmol m-3-3
POPO443-3- 0.5 mmol m 0.5 mmol m-3-3
Si(OH)Si(OH)44 12.0 mmol m 12.0 mmol m-3-3
NONO33-- exhausted on day 12 exhausted on day 12
Mesocosm experimentMesocosm experimentBergen 2003Bergen 2003
Year 2100: Diatoms > Dinophyceae (> Coccolithophores)
Present: Coccolithophores > Diatoms (> Dinophyceae > Chlorophyceae)
LGM: Diatoms (> Dinophyceae > Coccolithophores)
B. Delille, unpubl.B. Delille, unpubl.
2003 Mesocosm CT
1800
1850
1900
1950
2000
2050
2100
3 8 13 18 23
Day in May
CT m
mo
l.kg
-1
R. Bellerby et al., unpubl.
biologicalcarbonfixation
0 2 4 6 8 10 12 14 16 18 20
Day
DIC
(
µm
ol kg
-1)
Dissolved inorganic carbon
Year 2100
Present
LGM
Carbon over-production feedback
-20
0
20
40
60
80
100
1 3 5 7 9 11 13 15 17 19 21
Year 2100
Present
LGM
Day
Carb
on loss
(
µm
ol kg
-1)
Carbon loss = ∆DIC - ∆TPC - ∆DOC
Carbon over-production feedback
Transparent Exopolymer ParticlesTransparent Exopolymer Particles
Dissolved Polysaccharides
Cell density
Day
DOCDOC
Low COLow CO22 High COHigh CO22
DOCDOC
TEPTEP
Marine snowMarine snow
ExportExport
ExsudationExsudation
Sign of change negative feedback
Sensitivity ?
Capacity high
Longevity permanent vs. transient ?
Carbon over-production feedback
Engel et al. 2004 Nature 428, 929Engel et al. 2004 Nature 428, 929
FACE (Free Air CO2 Enrichment) Program
- with worldwide 33 experimental sites
- 16 sites in Europe
Research needs:Research needs:
Observational studies on combined COObservational studies on combined CO22 and T- and T-effectseffects - assess biological responses - assess biological responses
- unravel biogeochemical processes- unravel biogeochemical processesand potential feedbacksand potential feedbacks
through a suite of perturbation studiesthrough a suite of perturbation studies- laboratory experiments- laboratory experiments- mesocosm studies- mesocosm studies- open ocean CO- open ocean CO22 fertilization experiment fertilization experiment