synthesis workshop summary the climate-ocean regime shift hypothesis of the steller sea lion decline...
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Synthesis Workshop Summary
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
December 4-5, 2003Newport Beach, CA
11 Proposals funded by NOAA OAR/NOS CIFAR
Object: Synthesis Review Paper of the Research Results
Relate temporal variability in the physical system to the ecosystem changes
Workshop ParticipantsFunded Investigators:
M. Alexander, A. Capotondi (CDC)S. Bograd (PFEL)K. Coyle (UAF)B. Finney (UAF)G. Hunt, J. Jahncke (UCI)N. Kachel (PMEL)N. Mantua, C. Marzban (UW)H. Maschner (Idaho State) W. Maslowski (NPS)A. Miller, D. Neilson, E. Di Lorenzo, H.-J. Kim (Scripps)S. Okkonen (UAF)T. Royer, C. Grosch (ODU)A. Trites, E. Gregr (UBC)J. Wang (ARL)
Program Manager: J. Calder (NOAA)
Invited Contributors: L. Fritz (NMFS)J. Overland (PMEL)
Synthesis Paper Highlights
Title: The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion DeclineForum: Fisheries OceanographyAuthors: Trites, Maschner and all contributors
Thesis: Spatial and temporal variations in the ocean climate system are creating adaptive opportunities for high trophic levels which is the underlying mechanism for the decline of the Steller sea lion populations in the western Gulf of Alaska.
Important results:Temporal issue - 1970s to 1990s changesSpatial issue - East vs west asymmetry in Gulf of AlaskaBiogeographic transition point at 170WBasin-scale climate changes have regionally sensitive impactsUpscaling from local complexities to broadscale regularitiesEddy variance changes in western Gulf
Outline
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
Physical Ocean-Atmosphere Data Analysis
Ocean Model Results: Coarse and Eddy-Permitting
Bio-Geography: Samalga Pass Transition Point
Paleo-Perspective: Isotopes and Archeology
Outline
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
Physical Ocean-Atmosphere Data Analysis
Ocean Model Results: Coarse and Eddy-Permitting
Bio-Geography: Samalga Pass Transition Point
Paleo-Perspective: Isotopes and Archeology
• Analysis of COADS SST, 1950-97
• SST clusters into 5 dynamic regions
• regional differences in long-term
SST behavior in eastern Subarctic
Pacific
Bograd et al., 2004
Sea Surface Temperature Trends in the Gulf of Alaska
Nonlinear PCA results from
Marzan, Mantua, and
Hare:
based on 22 abiotic indices
from the Pacific for 1965-2001
NL PC1: 32% of variance
NL PC2: 23% of variance
Peterson and Schwing, 2003
SSTA
SLPA,WindA
“cool” “warm” “cool?”
North Pacific Regime Shifts: State Changes in Forcing
Modeled Gulf of Alaska coastal discharge
Royer and Grosch
Changes in Ekman pumping
Capotondi et al.
Pre-shift meanconditions1960-75Dec-May
Changeafter shift(1977-97)-(1960-75)
Outline
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
Physical Ocean-Atmosphere Data Analysis
Ocean Model Results: Coarse and Eddy-Permitting
Bio-Geography: Samalga Pass Transition Point
Paleo-Perspective: Isotopes and Archeology
Pycnocline (26.4) depth changesPeriod2 (77-97) – Period1 (64-75)
P = OWS P
G = GAK1
Capotondi et al.
Model vs. Obs PAPA Model vs. Obs GAK
1970 19701980 1990 2000 1980
Before 76-77 Shift
After 76-77 Shift
Difference
- More eddies north of Kodiak- Fewer eddies southwards
Kodiak Is.
Eddy-Permitting Model Eddy Surface Currents
Miller et al.
NPS Model SST along shelf break Deep Salinity along shelf break
Okkonen et al.
Naval Postgraduate School numerical model23 year (1979-2001) simulation with real winds
Physical-Biological Ocean Hindcast
(Chai et al. model)
Decrease in largezooplankton (and large phyto, small zoo) after the1976-77 shift…
…But occurs only during spring bloom
Alexander et al.
Outline
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
Physical Ocean-Atmosphere Data Analysis
Ocean Model Results: Coarse and Eddy-Permitting
Bio-Geography: Samalga Pass Transition Point
Paleo-Perspective: Isotopes and Archeology
Tananga Pass
Seguam
Pass
Am
ukta Pass
Sam
alga Pass
Akutan Pass
Unimak Pass
Bering Sea
Pacific Ocean
Um
nak Pass
>
Locations of Passes sampled May-June 2002
Coyle et al.
Samalga Pass forms a boundarybetween shelf water to the eastand open ocean waters to the west
Surface Salinity along
Aleutian Islands
Ladd et al.(2004)
East of Samalga Pass, ACC hasstrong influence
West of Samalga Pass,Alaska Stream has stronginfluence
Unweighted Means vs Transect and Species
Transect
Ak1 Un1 Tng Sgm Amk Smg Unk Ak2 Un2
Mea
n A
bund
anc
e (
No
. m-3
)
0
100
200
300
400
500
600
Calanus marshallaeN. plumchrus & N. flemingeriAcartia spp.
Unweighted Means by Transect and Species
Transect
Un1 Ak1 Tng Sgm Smg Un2 Ak2
Mea
n A
bun
dan
ce (
No
. m-3
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Thysanoessa inermisEuphausia pacifica
Coyle et al.
Abundance vs. Transect May-June 2002
5 2
5 4
- 1 7 8 - 1 7 6 - 1 7 4 - 1 7 2 - 1 7 0 - 1 6 8 - 1 6 6 - 1 6 4
5 2
5 4
- 1 7 8 - 1 7 6 - 1 7 4 - 1 7 2 - 1 7 0 - 1 6 8 - 1 6 6 - 1 6 4
5 2
5 4
- 1 7 8 - 1 7 6 - 1 7 4 - 1 7 2 - 1 7 0 - 1 6 8 - 1 6 6 - 1 6 4
5 2
5 4
- 1 7 8 - 1 7 6 - 1 7 4 - 1 7 2 - 1 7 0 - 1 6 8 - 1 6 6 - 1 6 4
Short-tailed shearwaters
Northern fulmars
Tufted puffins
Small alcids
Jahncke et al.
West ofSamalga Pass:Fulmars andAuklets(open oceanfood web)dominant
East of Samalga Pass:Shearwatersand Puffins(coastalfood web)dominant
Seabirds Reflect Biogeographical Boundaries
Outline
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
Physical Ocean-Atmosphere Data Analysis
Ocean Model Results: Coarse and Eddy-Permitting
Bio-Geography: Samalga Pass Transition Point
Paleo-Perspective: Isotopes and Archeology
Paleoproductivity
2000195019001850180017501700-25
-24
-23
8
10
12
13COpal (%)
Gulf of Alaska: GAK 4 Core
Year AD
Op
al (
%)
-22.0
-21.0
-20.0
10
20
30
13C
Op
al (
%)
GOA GAK 4
Skan Bay
13C
Bering Sea: Skan Bay Core Paleoproductivity > 1976 Regime-shift
Bering Sea:13C - decreaseOpal - variable
Gulf of Alaska: 13C - increaseOpal - increase
Finney et al.
Relative Abundance of SSL based on Archaeological Data
400
800
1200
1600
2000
2400
2800
3200
3600
01020304050 10 20 30 40 50
Below Average Percent SSL Above Average Percent SSL
Years B
efore P
resent
Climate
w a rm , m e sic
cool, m e sic
cool, w e t
Maschner et al.
Some Outstanding Questions
The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline
What mechanisms control the restructuring of the ecosystem by climate, especially concerning fish?
How do human activities and ecosystem interactions work with variable climate forcing to alter Steller sea lion populations?
Do Steller sea lions feed in eddies?
What can be said about changes in sub-surface conditions?
How does vertical mixing vary in space and time?
What other regime shifts may have occurred?
Synthesis Paper Highlights
Title: The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion DeclineForum: Fisheries OceanographyAuthors: Trites, Maschner and all contributors
Thesis: Spatial and temporal variations in the ocean climate system are creating adaptive opportunities for high trophic levels which is the underlying mechanism for the decline of the Steller sea lion populations in the western Gulf of Alaska.
Important results:Temporal issue - 1970s to 1990s changesSpatial issue - East vs west asymmetry in Gulf of AlaskaBiogeographic transition point at 170WBasin-scale climate changes have regionally sensitive impactsUpscaling from local complexities to broadscale regularitiesEddy variance changes in western Gulf
Extras
(a) trend 1• loadings increase west to east• warming from early 70’s• accelerated warming after 76
(b) trend 2• accentuates trend 1• pronounced drop after 58• rapid rise after 72• positive loadings = strong warming after 72
(c) trend 3• strong warming in eastern GOA during 57-58 event• broad warming after 76
(d) trend 4• strong interannual variability• impacts from El Niño events• strong loadings in coastal BC and WWD
Bograd et al., 2004
Sea Surface Temperature Trends in the Gulf of Alaska
Nonlinear PCA results from
Marzan, Mantua, and
Hare:
based on 45 biotic indices
from the Bering Sea and Gulf of Alaska for 1965-
2001
NL PC1: 39% of variance
NL PC2: 18% of variance
Kendall’s trends in Alaska adult SSL data(Marzban, Mantua and Hare)
99% ci --
99% ci --
For SSL data from 1970-2001
Seasonal Amplitude and Phase Changesin Coastal Freshwater Discharge
Royer and Grosch
Wavelet Analysis of Coastal Freshwater Discharge
Royer and Grosch
Naval Postgraduate School numerical model23 year (1979-2001) simulation with real winds
Okkonen et al.
Red line indicates shelf break (for Hovmuller diagram)
Temperature vs Transect; Unweighted MeansWilks lambda=.02144, F(64, 381.4 )=5.6421, p=0.0000
Vertical bars denote 0.95 confidence intervals
Akutan P
ass 1
Un
ima
k P
ass 1
Ta
nanga P
ass
Segua
m P
ass
Am
ukta P
ass
Sam
alg
a P
ass
Um
nak P
ass
Akutan P
ass 2
Un
ima
k P
ass 2
Transect
3.5
4.0
4.5
5.0
5.5
6.0
6.5
Te
mpe
ratu
re (
o C)
UpperMixedTemp LowerMixedTemp MeanTemp
Salinity vs. Transect; Unweighted MeansWilks lambda=.02144, F(64, 381.4 )=5.6421, p=0.0000
Vertical bars denote 0.95 confidence intervals
Akuta
n P
ass 1
Unim
ak P
ass 1
Tananga P
ass
Seguam
Pass
Am
ukta
Pass
Sam
alg
a P
ass
Um
nak P
ass
Akuta
n P
ass 2
Unim
ak P
ass 2
Transect
31.6
31.8
32.0
32.2
32.4
32.6
32.8
33.0
33.2
33.4
33.6
33.8
Salinity (
PS
U)
UpperMixedSal LowerMixedSal MeanSal
Coyle et al.
T and S vs. Transect May – June 2002
Schematic of Traditional Aleut Knowledge of Recent North Pacific Cycles
2000
1990
1980
1970
1960
1950
1940
1930
1920
1910
1900
1890
1880
1870
LowAverageHigh Average High
Gadids King Crab
Year
unknown
unknown
unknown
unknown
unknown
unknown
unknown
Maschner et al.