Climate impacts on Puget Sound circulation and ecology

Jan Newton

University of Washington

PNW estuaries have strong

influence from climate

Global influence on:

ocean conditions watershed conditions

local weather

NASA SeaWiFS Image

Estuaries receive the “triple whammy”

when climate varies:

1. Variation from ocean

2. Variation from local weather

3. Variation from rivers

WARM

COLD

temperature salinity determine density

FRESH

SALTY

+

less dense

more dense “thermocline” or “pycnocline”

WARM

FRESH

COLD

SALTY

“stratified” “mixed”

Density structure can be two different ways:

Lo nutrient Hi oxygen

Phytoplankton present

Hi nutrient Lo oxygen

No phytoplankton

Organic (primary) production:

Phytoplankton present

No phytoplankton

{ CO2 + H2O C(H2O) + O2 }

sunlight nutrients

WELL-MIXED OXYGEN

HIGH OXYGEN

LOW OXYGEN

“stratified” “mixed”

Oxygen structure can be two different ways:

N

S

NO3-

NO3-

NO3-

NO3-

NO3-

NO3-

NO3-

NO3-

Downwelling Upwelling

1. Variation in coastal ocean:

NO3-

NO3-

1. Variation in ocean: seasonal, interannualUpwelling

WIN

D

Downwelling

WIN

D

Temperature Temperature

1. Variation in ocean: seasonal, interannualUpwelling

WIN

D

Chlorophyll

Downwelling

WIN

D

Chlorophyll

The depth of the thermocline off Oregon coast was much deeper following El Niňo than La Niňa.

This affects not only the temperature but also the nutrients available at the surface.

Will affect nutrient-limited phytoplankton biomass and species in coasts and estuaries.

1. Variation in ocean: thermocline depth nutrient availability

Smith et al. 2000

April 1999

April 1998

110 m

10 m

Dep

th (

m)

Dep

th (

m)

Distance from shore (km)

-4000

-2000

0

2000

4000

6000

8000

10000

98 99 00 01

Sea-Tac solar radiation (W/m 2 )solar - 10-y mean30-d running avg.

2. Variation in local light availability:

Light availability in PNW can vary significantly in both magnitude and timing.

Much of PNW phytoplankton prod’n is light-limited.

Variation in primary prod’n will affect trophic transfer and water quality. NCDC Sea Tac data

N

NO3-

NO3-

NO3-

NO3-

NO3-

NO3-S

NO3-

NO3-

Downwelling Upwelling

Willapa Integrated Primary Production

0

1000

2000

3000

4000

5000

6000

Oct-

97

No

v-9

7

Dec-9

7

Jan

-98

Feb

-98

Mar-

98

Ap

r-98

May-9

8

Ju

n-9

8

Ju

l-98

Au

g-9

8

Sep

-98

Oct-

98

No

v-9

8

Dec-9

8

Jan

-99

Feb

-99

Mar-

99

Ap

r-99

May-9

9

Ju

n-9

9

Ju

l-99

Au

g-9

9

Sep

-99

Oct-

99

No

v-9

9

Dec-9

9

mg

C m

-2 d

-1

Toke Pt. Bay Center Oysterville Naselle G-33

El Niño versus La Niña primary prod’n

Newton & Horner, 2003

Local and large-scale climate forcing of Puget Sound oceanographic properties on seasonal to interdecadal timescales

Moore et al., 2008

Abstract-

The influence of climate on Puget Sound oceanographic properties is investigated on seasonal to interannual

timescales using continuous profile data at 16 stations from 1993 to 2002 and records of sea surface temperature

(SST) and sea surface salinity (SSS) from 1951 to 2002. Principal components analyses of profile data identify

indices representing 42%, 58%, and 56% of the total variability at depth-station combinations for temperature,

salinity, and density, respectively, and 22% for water column stratification. Variability in the leading pattern of

Puget Sound water temperature and salinity profiles is well correlated with local surface air temperatures and

freshwater inflows to Puget Sound from major river basins, respectively. SST and SSS observations are

informative proxies for the leading patterns of variations in Puget Sound temperature and salinity profiles.

We find that Puget Sound’s oceanographic properties also have significant correlations with Aleutian Low, El Niño-Southern Oscillation, and Pacific Decadal Oscillation variations in winter that can persist for up to three seasons or reemerge the following year. However, correlations with large-scale climate variations are weaker compared to those with local environmental forcing parameters.

• Anticipated changes in annual precipitation due to climate change.

• Signal from drought/flood years

• Much of PNW phytoplankton prod’n is light-limited.

• How will this affect stratification, circulation, growth conditions, and species composition ?

USGS & Env Canada data

Mote, CIG

3. Variation in regional river flow:

2000-2001 Drought2000-2001 Drought

“Second worst in Washington State recorded history.”

Driest since 1976-77

One of five driest in past 100 years

WA Ecology website

Fraser River

Snohomish River

Reduced regional river flows evident:

Skagit River

Willapa River

USGS & Env Canada data

Core station

Rotational station

Washington State’s Long-term Marine Waters Monitoring Program

Southern Hood Canal

Stratification:

10

12

14

16

18

20

22

24

90

91

92

93

94

95

96

97

98

99

00

01S

alin

ity (

PS

U)

Surface salinity

Year

Del

ta S

igm

a-t

Year

0

5

10

15

20

90

91

92

93

94

95

96

97

98

99

00

01

10

12

14

16

18

20

22

24

90

91

92

93

94

95

96

97

98

99

00

01

Bottom salinity

Year

Stratification: what is driving this reduction?

WA Ecology data

dept

h

Density (sigma-t)

Newton et al., 2003

0

2

4

6

8

10

90

91

92

93

94

95

96

97

98

99

00

010

2

4

6

8

10

90

91

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94

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01

0

2

4

6

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90

91

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96

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0

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00

01

1. Bellingham BayStratification (delta sigma-t) vs. time:

2. Possession Sound1

6

5

4

3

2

5. Budd Inlet

4. Commencement Bay

6. N. Hood Canal

0

2

4

6

8

10

90

91

92

93

94

95

96

97

98

99

00

01

3. Elliott Bay

WA Ecology data

<0%

0-30%

30-49%

50-69%

>70%

Percent change instratification

(10-y mean – Oct 00-Sep 01) / 10-y mean)

Mean = 56%

Grays Harbor = 52%

Willapa Bay = 49%

Newton et al., 2003

Density stratification affects:

• Water quality (e.g., hypoxia)

• Phytoplankton bloom timing (with impacts on pelagic food-web

• Circulation and flushing (e.g., transport of organisms, pollution)

Joint Effort to Monitor the Strait (JEMS)

JEMS Partners:

MEHP

WA Dept. Ecology

King County

UW PRISM

NOAA

Friday Harbor Labs

JEMS line

fresher, warmer water from Puget Sound and Georgia Basin flowing out

colder, salty water from Pacific Ocean flowing in

North Canada

South U.S.A.

Flow in Strait of Juan de Fuca:

Thomson, 1994

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 0 Temperature (oC)

8

9

2000 2001 2002

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 1 Temperature (oC)

88.5

2000 2001 2002

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 2 Temperature (oC)

8

2000 2001 2002

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 0 Salinity (PSU)

2000 2001 2002

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 1 Salinity (PSU)

2000 2001 2002

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

50

100

150

Depth

(m

)

Station 2 Salinity (PSU)

2000 2001 2002

Temperature

Salinity

Compare Sept 2000 with Sept 2001:

Why is there cooler saltier water in 2000 ??

JEMS data

Newton et al., 2003

Cross-Channel Density Gradient

9/2/99

Dep

th (

m)

0 1 2

20406080

100120140

10/15/99

0 1 2

20406080

100120140

11/23/99

0 1 2

20406080

100120140

12/20/99

0 1 2

20406080

100120140

1/27/00

Dep

th (

m)

0 1 2

20406080

100120140

2/12/00

0 1 2

20406080

100120140

3/5/00

0 1 2

20406080

100120140

3/29/00

0 1 2

20406080

100120140

5/2/00

Dep

th (

m)

0 1 2

20406080

100120140

7/5/00

0 1 2

20406080

100120140

8/31/00

0 1 2

20406080

100120140

11/14/00

0 1 2

20406080

100120140

1/15/01

Dep

th (

m)

0 1 2

20406080

100120140

3/23/01

0 1 2

20406080

100120140

6/25/01

0 1 2

20406080

100120140

7/29/01

0 1 2

20406080

100120140

9/13/01

Station

Dep

th (

m)

0 1 2

20406080

100120140

1/30/02

Station0 1 2

20406080

100120140

3/25/02

Station0 1 2

20406080

100120140

Colorbar

Density (sigma-t)22

26

N S

Cooler, saltier water drives a weaker density gradient during Sep 2000 than in Sep 2001 Lo

Hi

Newton et al., 2003

S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A

0

20

40

60

80

100

Depth

(m

)

Geostrophic Velocity (cm/s)

0

2000 2001 2002

Geostrophic Velocity (cm/sec)Low River Flow

Weak Density Gradient

Decreased Outflow Velocity

Water stays in Puget Sound

longer Four-fold difference in speed of inland water outflow.

(this means how fast the water flows out the Strait)

Newton et al., 2003

Conclusions

• Puget Sound, an estuary, integrates climate-related impacts from the ocean, atmosphere, and watershed.

• While predominantly forced by oceanic influence, there is a significant affect from freshwater input, with measurable impacts on stratification and circulation.

Conclusions

• Drought period increased salinity of the estuarine waters, leading to higher density surface layer and weaker stratification.

• Higher salinity waters with a weaker density gradient result in decreased outflow velocity and longer residence time in estuary.

• Implications of both of these effects on oxygen, phytoplankton blooms, trophic transfer, and transport or retention of larvae, species, and pollutants need further investigation.

Conclusions

• Assessment of the various climate-related impacts on Puget Sound physics is complex but must be addressed together.

• Only then can the chemical and biological implications be evaluated.

• While multi-disciplinary evaluations on estuaries is complicated, in light of climate change, this needs regional attention.