synthesis workshop summary

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

Amukta Pass

Samalga 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

ance

(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

bund

ance

(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

Opa

l (%

)

-22.0

-21.0

-20.0

10

20

30

13C

Opa

l (%

)

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 50Below Average Percent SSL Above Average Percent SSL

Years Before Present

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

Aku

tan

Pas

s 1

Uni

mak

Pas

s 1

Tana

nga

Pas

s

Seg

uam

Pas

s

Am

ukta

Pas

s

Sam

alga

Pas

s

Um

nak

Pas

s

Aku

tan

Pas

s 2

Uni

mak

Pas

s 2

Transect

3.5

4.0

4.5

5.0

5.5

6.0

6.5

Tem

pera

ture

(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

Aku

tan

Pas

s 1

Uni

mak

Pas

s 1

Tana

nga

Pas

s

Seg

uam

Pas

s

Am

ukta

Pas

s

Sam

alga

Pas

s

Um

nak

Pas

s

Aku

tan

Pas

s 2

Uni

mak

Pas

s 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

Sal

inity

(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 HighGadids King Crab

Year

unknown

unknown

unknown

unknown

unknown

unknown

unknown

Maschner et al.