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)