NutrientsSalinityTemperatureTurbidityDissolved Oxygen

Chlorophyll

www.sfbay.wr.usgs.gov/access/wqdata

1980 1985 1990 1995 2000 2005

North Bay

South Bay

1980 1985 1990 1995 2000 20050

20

40

60

Chl

orop

hyll

(g/

L)

Story 1: North Bay

USGS + Interagency Ecological Program

1980 1985 1990 1995 2000 20050

20

40

60

Chl

orop

hyll

(g/

L)

Corbula amurensis

Interagency Ecological Program

0

1000

2000

3000

Per

m3

C opepod: Eurytem ora a ffin is

0

40

80

Ind

ex

M ysid Shrim p: N eoym sis m ercedis

1975 1980 1985 1990 1995 2000 2005

0

20

40

60

80

Ind

ex

Striped bass juven iles

California Department of Fish & Game

Chlorophyll a (g/L) 1977-1998

Story 2: South Bay

Chlorophyll a (g/L) 1977-2004

% per year

Seasonal Kendall Test (Helsel & Hirsch 1992)

• Ecologically Important• NOT related to nutrient (N,P) increases

Growth Mortality

Transport

ResourcesLight

Nutrients

ImpairmentsHerbicidesMetals

Why is phytoplankton increasing in San Francisco Bay?

Four Hypotheses

14

23

1900 1920 1940 1960 1980 2000

0

20

40

60

Res

ervo

ir C

apac

ity (

km3 )

Growth

ResourcesLight 1

McKee et al. (2006)

1960 1970 1980 1990 2000

0

1

2

3Sediment Input (Mt/y)

“sediment yield of the Sacramento River decreased by about half from 1957-2001” (Wright & Schoellhamer 2004).

Growth

ImpairmentsMetals 2

City of San Jose, Environmental Services (2006)

3

1980 1990 2000

0

40

80

120Upwelling Intensity

NOAA PFEL

Tra

nspo

rt

English Sole

0

10

20

30

40

CP

UE

1980 1990 2000

0

10

20

CP

UE

SpeckledSanddabs4

California Dept. Fish & Game

Mortality

Lessons

• aquatic ecosystems are in perpetual state of change• unraveling the processes is particularly challenging in estuaries• water quality is influenced by connectivity to the coastal ocean and local watersheds• alien species can be as disruptive as chemical pollution• phytoplankton dynamics are influenced by more than nutrient loadings

Thanks to Tara Schraga, Kate Dallas, Alan Jassby, Jan Thompson, Dave Schoellhamer, Kathy Hieb, San Jose Environmental Services, Regional Monitoring Program

Photo: Steve Hager

Chlorophyll varies at time scales from hours to decades

Growth Mortality

Transport

ResourcesLight

Nutrients

ImpairmentsHerbicides

Metals

Conceptual Model

Nancy Monsen

Selenium concentrations in fish

1986n=5

1990n=10

1999n=15

1986n=10

1990n=25

2000n=15

Se c

on

c. (

µg

/g)

***

0

10

20

30

40

50Mean ± SE

Striped Bass

CDFG (data 1986, 1990)

*

White Sturgeon

Robin Stewart (USGS):

Seasonal Kendall Test for Trends (Helsel & Hirsch 1992)

% per year

% per year

Not associated with nutrient increases

% per year

Estimated Primary Production (g C/m2-y)

120

215

0 200 400 600 800

C hl*E /k

0

1000

2000

3000

4000

Pri

ma

ry P

rod

uct

ion

(m

g C

/m2

-d)