ocean acidification, warming and the biological carbon pump · l&o 2015 poc (ccmp 1336) tep ....
TRANSCRIPT
Tullio Rossi Jonathan Jones Anna James Jan Taucher Shalin Seebah Graduate Students, past and present, working on OA in my lab:
Julia Sweet
Ocean Acidification, Warming and the Biological Carbon Pump
Uta Passow MSI, UC Santa Barbara
Caitlin Fairfield
Collaborators: Mark Brzezinski, Craig Carlson, Ed Laws
Lab Assistants:
S2-9895 11:40 Th. 26Mar Diam. 6-7
pCO2
today
370
Year 2100
~750 µatm
irradiance
pH ~8.1 ~7.8
mixing
Some direct and indirect changed to the abiotic environment of the surface ocean:
- ocean acidification
- light climate - nutrient availability & stoichiometry
nutrient input
Global Change
- temperature
- stratification/ turbulence
Adapted Rost et al. 2008
- trace element availability - exoenzyme activity - saturation state of CaCO3
Introduction
- allochthonous inputs (N, Fe)
- deoxygenation, OMZ
- sea level rise
CO2
DIC POM
Allochthonous nutrient input
Surface layer Export flux
DIC nutrients
100 yrs. to surface
10 yrs. to surface
Carbon Sequestration by the Biological Pump
DIC & Nutrients
1000 yrs. to surface
~ 100 m
~ 1000 m
Euphotic zone M
esopelagic zone D
eep Ocean
& DOM
Vertical migration
Physical transport
Introduction
Passow & Carlson 2012
Sequestration flux
Gravitational settling
Species/ Population
Community
Ecosystem
Global Biochemical Cycle
Physiological Response
1 2 3 multiple
What we want to know (BCP) What we can
measure well
Models
The Problem: An Analysis of Relevant Scales Introduction
Adapted Arrigo 2007
Ambient Temp., pCO2
Future Temp., pCO2
Introduction Hypothesis on TEP, aggregation and carbon flux
TEP = Transparent Exopolymer Particles: Sticky exopolysaccharides that form the matrix of most sinking marine snow
TEP in ug Xeq. L-1
Rossi et al. in prep.
Skeletonema costatum
3000
3500
4000
4500
present future
POC in ug L-1
1000120014001600180020002200240026002800
present future
POC & TEP production as a function of pCO2 (exp. 1)
Note: Population level: Higher pCO2 • has no impact on POC • leads to increased TEP
Batch growth till nutrient limitation
Carbon Fixation
Carbon Fixation
Taucher et al. L&O 2015
POC
TEP
Temp. effect
Temp. & pCO2 effect
POC & TEP production as a function of pCO2 & temperature (exp. 3)
T. weissflogii: (CCMP 1336)
Note: Population level: Higher pCO2 • no impact on POC • increased TEP Higher temperature • increased POC • Increased TEP
Batch growth after N-limitation
POC
TEP
Temp. & pCO2 effect
Dactyliosolen fragilissimus pCO2 effect
Note: Population level: Higher pCO2 • increased POC !!! • increased TEP
Higher temperature • unchanged POC !!! • decreased TEP !!!
Batch growth after N-limitation
POC & TEP production as a function of pCO2 & temperature (exp. 3) C
arbon Fixation
Taucher et al. L&O 2015
0
500
1000
1500
Amb Fut 1 Fut 2 Amb Fut 1 Fut 2
TEP
µg G
Xeq
L-1
15⁰C
20⁰C
Aggregation
Seebah et al. PLOS ONE 2014
T. weissflogii: (CCMP1336)
TEP Production as a function of pCO2 & temperature (exp. 6)
Note: Population level: Higher pCO2:
• No consistent effect on TEP!!!
Higher temperature: • increased TEP
Why is there no consistent response pattern of POC and TEP to increased temperature and pCO2?
T. weissflogii: Dactyliosolen fragilissimus Skeletonema costatum
Three coastal diatoms, all bloom forming
1. Keeping Perspective
Single abiotic stressor experiments: A fixed change in stressor may result in three different answers
Perf
orm
ance
, e.g
. gro
wth
Environmental parameter, e.g. temperature, irradiance, pCO2
Optimum
Optimum
Lethal limit
Inhibition threshold
Growth range
Performance (Optimum, Response) Curves
Carbon Fixation
0
100
200
300
400
500
15C Amb 20C Amb 15C Fut 20C Fut
POC
per
cel
l
050
100150200250300350400450
15C Amb 20C Amb 15C Fut 20C Fut
TEP
per c
ell
2. Interactive effects of multiple stressors (exp. 2)
CO2: P < 0.001 Temp: P < 0.001 CO2*Temp: P < 0.001
CO2: P < 0.001 Temp: P < 0.001 CO2*Temp: P < 0.001
pCO2 & Temperature
0
50
100
150
200
250
300
Amb HL Amb LL Fut HL Fut LL
POC
per
cel
l
-500
50100150200250300350
Amb HL Amb LL Fut HL Fut LL
TEP
per c
ell
CO2: P < 0.05 (only POC) Light: P < 0.001 CO2*Light: P < 0.001
CO2: NS Light: P < 0.001 CO2* Light: NS
Passow & Laws subm.
T. Weissflogii (CCMP 1053) pCO2 & light C
arbon Fixation
Carbon Fixation
Future Temp., pCO2
Hypothesis on POC and TEP production C
arbon Fixation
Sin
king
vel
ocity
m/d
Tota
l Agg
rega
te A
rea
mm
2 Sinking Velocity
Aggregation
TEP in ug Xeq. L-1
1000
1500
2000
2500
3000
present future
Aggregation & sinking velocity as a function of pCO2 (& TEP)(exp. 1)
Skeletonema costatum
Rossi et al. in prep.
0100200300400500600700800900
present future 0
10
20
30
40
50
60
70
80
90
present future
0
1
2
3
4
Amb Fut 1 Fut 2 Amb Fut 1 Fut 2Tota
l Agg
rega
te V
olum
e cm
3
0
500
1000
1500
Amb Fut 1 Fut 2 Amb Fut 1 Fut 2
TEP
µg G
Xeq
L-1
15⁰C
20⁰C
20⁰C
15⁰C Aggregation
Seebah et al. PLOS ONE 2014
T. weissflogii:
Aggregation as a function of pCO2 & temperature (and TEP)(exp. 6)
Aggregation: Higher pCO2:
• decreased aggregation (independent of TEP)
Higher temperature: • decreased aggregation
(increased TEP)
0
50
100
0 5 10 15
Equivalent Spherical Diameter (ESD) mm
Sin
king
vel
ocity
m d
-1
Sinking velocity as a function of pCO2 & temperature (exp. 6)
20⁰C; more TEP
15⁰C
Seebah et al. PLOS ONE 2014
Sinking Velocity
No pCO2 effect
Aggregation
Future Temp., pCO2
Sinking Velocity Hypothesis on aggregation and sinking velocity
CO2
DIC POM
Surface layer
Carbon Sequestration by the Biological Pump
~ 100 m
~ 1000 m
Euphotic zone M
esopelagic zone D
eep Ocean
& TEP (DOM)
Conclusions
Allochthonous nutrient input
DIC & Nutrients
↑ pCO2 & ↑temperature
Summary & Conclusions Carbon Fixation
• No a priori predictions with regards to carbon partitioning (between TEP and POC and DOC) as a function of increased temperature or pCO2 currently possible. The response is a
• function of stressor in relation to response curve of that species
• function of species physiology • function of interactive effects of multiple environmental
stressors
Conclusions Aggregation & Sinking • Aggregation rate decreased at high pCO2 or high temperature • Sinking velocity decreased at high temperature (more TEP),
but no pCO2 effect per se (or maybe a high TEP effect).
BCP • Diatom aggregation section of the Biological Carbon Pump
would suggest a weakening of carbon flux under high pCO2 and high temperature conditions
Gotschalk