Year
1950 1960 1970 1980 1990 2000 2010Tem
pera
ture
ano
mal
y (º
C)
-2
-1
0
1
2
Scripps pier Sea Surface Temperature
Mark D. OhmanScripps Institution of OceanographyUniversity of California, San Diego
Pelagic ecosystem responses to climate forcing:
Linear tracking or threshold dynamics?
U.S. LTER Network - 26 sites including terrestrial, aquatic, & human-dominated ecosystems
Scheffer et al. 2009, Nature
Fold Bifurcation
Preferred state A
Preferred state B
LinearThreshold
California Current Ecosystem LTER A Coastal Upwelling Biome
CCE: leverages 62-yr CalCOFI time series
Multiple, interacting time scales
of ecosystem change
Progressive, long-term changes
in the California Current Ecosystem
Scripps Pier Temperature
DensityStratification
N2CalCOFI line 80
Lavaniegos & Ohman (2007) Progress in OceanographyKim and Miller (2007) J. Physical Oceanography
Long-term Changes in Vertical Stratification
Year
1950 1960 1970 1980 1990 2000Tem
pera
ture
ano
mal
y (º
C)
-2
-1
0
1
2
Salps
Year1950 1960 1970 1980 1990 2000
C B
iom
ass
(Log
mg
C m
-2 )
0.0
1.0
2.0
3.0
Salp biomass
photo: D.Wrobel
Buoy
ancy
Fre
quen
cyan
omal
y (
N2 ,
s-1)
Year
Year
Long
itude
Sta. M deep-sea benthic observatoryK. Smith
POC fluxes, SCOD, benthic macrofauna interactions4100 m deep
Links to BiogeochemistryDeep Sea C fluxes?
export fluxes
Salps
Year1950 1960 1970 1980 1990 2000
C B
iom
ass
(Log
mg
C m
-2 )
0.0
1.0
2.0
3.0
Sta. M
OceanSurfacewaters
Long-Term Decrease in Ocean Transparency(Secchi disk depth)
annual averagesinshore region
CalCOFIregion
Aksnes and Ohman 2009
Ohman & Romagnan (in prep)
inshoreoffshore
Wei
ghte
d M
ean
Dep
th (
m)
-- Night-- Day
Cycle 1 Cycle 3Cycle 4Cycle 2Cycle 5
Body size (µm ECD)
Planktonic Copepods
CCE-P0605
Exchanging Space for Time:Spatial differences as an analog of temporal change
Copepod Diel Vertical Migrationvs. water column transparency
Beam attentuation (m-1)
0.0 0.2 0.4 0.6
Am
plitu
de o
f DV
M (m
)
0
100
200
300
Changes in transparency over time
Spatial differences in Transparencyaffect zooplankton vertical distributions
SanDiego
Thecosome Pteropods
1950 1960 1970 1980 1990 2000 2010
Log
(x+1
), N
o m
-2
0.0
1.0
2.0
3.0
Heteropoda (Atlanta spp.)
1950 1960 1970 1980 1990 2000 2010
Log
(x+1
), N
o m
-2
0.0
1.0
2.0
3.0
Foraminifera
Year
1950 1960 1970 1980 1990 2000 2010
Log
(x+1
), N
o m
-2
0.0
1.0
2.0
3.0
Southern California
Ohman et al. (2009) GRL
Consequences of lowered seawater pH and undersaturation w.r.t. aragonite in the CA Current System ?
(cf. Feely et al. 2008)
Spring cruises
Importance of long term research:detecting thresholds of change
Natural modes of climate variability:
interannual and interdecadal changes
in the California Current Ecosystem
Ohman and Di Lorenzo (in prep)
Brinton data source - CalCOFI
Euphausia pacifica
1950 1960 1970 1980 1990 2000 2010
-1
0
1 anomalies
Log
No.
m-2
Year
E.p.recon vs. E.p.obs
Year
Sea Surface Height AR1 model
Interannual variability
M. Ohman
Major El Niño’s
Ohman and Di Lorenzo (in prep)
Brinton data source - CalCOFI
1950 1960 1970 1980 1990 2000 2010
-1
0
1
Nyctiphanes simplex
Log
No.
m-2
anomalies
Year
N.s.recon vs. N.s.obs
Year
PDO AR1 model
Interdecadal variabilityPDO
J. Gómez
Di Lorenzo et al. 2008, GRL
North Pacific Gyre Oscillation (NPGO)
NPGO initiallydiagnosed froma ROMs model
Interdecadal variability
Spatial dimensions of climate forcing:
differential effects on co-occurring species
curl-driven upwelling
coastal boundary upwelling
Rykaczewski and Checkley (2008) PNAS
Distinction between:Coastal boundary upwellingWind-stress curl upwelling
Typical VerticalVelocity(m day-1)
0-1
7-12
San Diego
Santa Cruz
Rykaczewski and Checkley (2008) PNAS
Curl-driven upwelling
Nutricline depth
Chla
Long-term increase in curl-driven upwelling
Coastal boundary upwelling
σθ
Rykaczewski & Checkley 2008
PNAS
CCE-LTERprocess cruises
Upwelling velocity w (m d-1)
Biom
ass
spec
tral
slo
pe (
g m
m-2)
Upwelling velocity w (m d-1)
Biom
ass
spec
tral
slo
pe (
g m
m-2)
Zooplankton body sizeis proportional to upwelling velocity
Coastal boundary upwelling: anchovy
Wind stress curl driven upwelling: sardine
Climate change may act at the
mesoscale and sub-mesoscale
Spatial dimensions of climate forcing:
N
S
Temp
Chl-a
(N.B. glider and SeaWifs imagesare on different color scales)
R. Davis, M. Ohman - glider imageM. Kahru – satellite imagesP. Franks - composition
0 m
400 m
Mesoscale & sub-mesoscale ocean features
Biophysical gradients at ocean fronts
Salinity
Potential Density
Acoustic Backscatter
Temperature
Chlorophyll-a
Acoustic Backscatter(750 kHz)
Potential Density
Salinity
34.5
33
16
0
27
24
4
090
55
0
500
°CdB
Volts
PSU
Sigmaθ
350 km 0 kmLine 80 Section
Temperature
Pres
sure
(db
)
nearshoreoffshore
Spray ocean glider
Jesse PowellScripps, CCE
graduate student
Russ Davis,Dan Rudnick,Mark Ohman
(off Pt. Conception)
Quantum Yield (φ ph)
Latitude
32.70 32.75 32.80 32.85 32.90
NASC
m/nm
i2
0
200
400
600
800
1000
FishKrillLarvae
Calanoid copepods
nauplii
Acoustic biomass
SouthDistance along section (km)
Distance along section (km)
North
Synechococcus biomass
Bacterial C production
Prochlorococcus biomass
Diatom biomass
Wang
Taylor,Landry
Taylor,Landry
Symo,Azam
Ohman
Koslow,Lara-Lopez
Sections across the “A-Front”
Total Biomass > 202 µm
fish krill
NorthSouth front
(offshore, Southern CA Current)
Ocean hotspotsN
omin
al d
epth
(m
)
NorthSouth
Human perceptions of
(and responses to) Climate Change
Coda:
Part of the
LTER Maps and Locals (MALS) project:
Fish species landed in San Diego during El Niño or La Niña
Zhang et al. (in review) Fishermens’ perspectives on climate variability
El NiñoLa Niña
Prop
ortio
n
Fish species
Only 12.9 % of these respondents unambiguously agreed that climate change is a possibility
The broader American public, in 2010: 71% (Yale) 74.5% (Stanford)
Interviews with captains of commercial passenger fishing vessels (CPFVs)
Time frame: April to July 2010Locations: Mission Bay and Point LomaTotal effective samples: 62 (total number of CPFVs in these two locations in 2009: 83)
SummaryExamples of climate influences on the California Current Ecosystem LTER site:
Processes operate on multiple, interacting time scalesProgressive, long-term changesInterannualInterdecadal
Importance of the spatial dimension in climate responsesWind stress curl vs. coastal boundary upwellingPossible nonlinear effects of ocean “hot spots”
Best conceptual model for biotic responses ?Linear tracking of the physical environmentThresholdsFold bifurcation with stabilizing mechanisms
1950 1960 1970 1980 1990 2000 2010
-1
0
1
Log
No.
m-2
anomalies1950 1960 1970 1980 1990 2000 2010
-1
0
1 anomalies
Log
No.
m-2
Salps
Year1950 1960 1970 1980 1990 2000
C B
iom
ass
(Log
mg
C m
-2 )
0.0
1.0
2.0
3.0
fin
-0.01
00.01
0.02
0.03
0.040.05
0.06
0.07
0.080.09
0.1
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006 -11
-6
-1
4
9
14Area1NOI
-0.01
00.01
0.02
0.03
0.040.05
0.06
0.07
0.080.09
0.1
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006 -11
-6
-1
4
9
14Area1NOI
Long-Term Variability in Front Frequencysatellite SST imagery
Related to variation in climate (NOI)
Arrows indicate coincident peaks
Kahru and Manzano (in prep.).
Southern California Current
Front FrequencyNOI
Fron
t Fr
eque
ncy
(pro
port
ion
of r
egio
n)
NO
I
End-to-end Observing System – Southern California Current SystempCO2 to marine mammals, integrated with 4D ocean modeling
Chl-a shown at surface;salinity in vertical section
Pacific sardineNorthern anchovy
Southwest Fisheries Science CenterNational Marine Fisheries Service
Preliminary study of an Oceanic FrontSST (º C)San Diego
“A-front” study
