Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
The role of nutrients in Puget Sound food webs: Insights from empirical and
modeling studiesCorreigh Greene & Chris Harvey
NOAA Fisheries
Do nutrients affect marine survival of Pacific salmon?• 40-year declines of Pacific salmon• Testing “bottom-up” hypotheses explaining declines• Reconstructing long-term patterns of primary
production in Puget Sound from growth in geoducks
• What happened since the 1980’s and can we improve the situation for juvenile Chinook, coho and steelhead?
• How do we improve the accuracy of adult return forecasting with early marine survival data: to better manage harvest, hatcheries and natural spawning?
• What actions can we take to improve marine survival?
Advance wild salmon recovery and sustainable fisheries
Objectives of the Salish Sea Marine Survival Project
Declines of salmon in the Salish Sea
SS CB WB HC JD SG CG JS NS CstSub-basin
Po
pu
lati
on
tre
nd
SS CB WB HC JD SG CstSub-basin
Chinook
Coho
Steelhead
Chum
Pink
Sockeye
Puget Sound
Strait of Georgia
Declines in Salish Sea Marine Survival
Washington / B.C. Coast
0.0%
2.5%
5.0%
7.5%
10.0%
12.5%
15.0%
17.5%
20.0%
1974 1979 1984 1989 1994 1999 2004 20090.0%
2.5%
5.0%
7.5%
10.0%
12.5%
15.0%
17.5%
20.0%
1974 1979 1984 1989 1994 1999 2004 2009
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
8.0%
1974 1978 1982 1986 1990 1994 1998 2002 2006 2010
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
1974 1978 1982 1986 1990 1994 1998 2002 2006 2010
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
1974 1978 1982 1986 1990 1994 1998 2002 2006 2010
Coho
Chinook
Steelhead0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
8.0%
1974 1978 1982 1986 1990 1994 1998 2002 2006 2010
Marine survival vs abundance trends
~ 350,000
~ 50,000
~ 20%
~ 3%
Ad
ult
ab
un
dan
ce
Skagit River coho
Current = 10-12%
of historical!
Ultimately, must weigh the contribution of:
• Local, human influence (water quality, predator management, hatchery management)
• Regional or global impacts (climate change, ocean acidification, natural cycles)
Hypotheses
A. Bottom-up processes that drive Chinook, coho and forage fish prey availability have changed, and salmon aren’t able to compensate.
B. Top-down processes contributing – More predators making situation worse. Eating larger juvenile steelhead, resident salmon and forage fish.
C. Multiple factors may compound the problem:• Microbes & disease• Contaminants• Habitat loss• Cumulative effects
Co
ho
sm
olt
-to
-ad
ult
su
rviv
al
Copepod community index
R² = 0.52
South Sound
0.0%
1.0%
2.0%
3.0%
4.0%
-0.2 -0.1 0 0.1 0.2 0.3-0.3
R² = 0.74
-0.3 -0.2 -0.1 0 0.1 0.2 0.3
Central Basin
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
R² = 0.59
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
Whidbey Basin
-0.3 -0.2 -0.1 0 0.1 0.2 0.3
R² = 0.62
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
-0.3 -0.2 -0.1 0 0.1 0.2 0.3
Hood CanalZooplankton station
Evidence for “bottom-up” effects: Zooplankton and coho survival (2003-10)
J. Keister
A tangled web of possibilities
Marine survival
Marine mammals
Body size
ZooplanktonForage fish
Diatoms
Habitat loss
NutrientsGlobal warming
&ocean acidification
A tangled web of possibilities
Qualitative modeling of hypotheses
Environmental drivers
Phytoplankton
Pelagic foodweb
Impacts of people
Salmon traits
Model results
Variables Perturbation Surv Abund
Sunlight ↑
Winter Storms ↑
Precipitation ↑
Stratification ↑
Temperature ↑
River Flow ↑
Upwelling ↓
Turbidity ↓
Dissolved Oxygen ↓
Variables Perturbation Surv Abund
Nutrients ↑
Microplankton ↑
Microbial Detritivores ↑
Diatoms ↓
Variables Perturbation Surv Abund
Gelatinous Zooplankton ↑
Other Salmon ↑
Marine Mammals ↑
Zooplankton ↓
Forage Fish ↓
Ichthyoplankton ↓
Piscivorous Fish ↓
Piscivorous Birds ↓
Variables Perturbation Surv Abund
Hatcheries ↑
Harvest ↑
Habitat Loss ↑
CO2 ↑
Global Warming ↑
Contaminants ↑
Disease ↑
Probability of decline (%)
0 20 40 60 80 100
Environmental drivers
Phytoplankton production
Pelagic foodweb groups
Impacts of people
Reconstructing primary production
Uncertainties• Geoducks may not eat just phytoplankton• Geoduck growth may reflect benthic conditions, not water column• Temperature affects both geoduck growth and primary production
Evergreen College
Bryan Black
Ge
od
uck
gro
wth
ind
ex
Year
Source: Bethany Stevik (WDFW)
Reconstructing primary production• Link growth with temperature and Chlorophyll measurements
at DOE water quality monitoring stations
Chlorophyll a
Ge
od
uck
gro
wth
• After accounting for effects of temperature…
• Lots of noise, so other factors appear to affect growth
Reconstructing primary production• Link growth with temperature and Chlorophyll measurements
at DOE water quality monitoring stations
Chlorophyll a
Ge
od
uck
gro
wth
• After accounting for effects of temperature…
• Lots of noise, so other factors appear to affect growth
Reconstructing primary production
Next steps
• Whidbey Basin geoducks
• Refine models using other water column metrics
• Find appropriate time series to extend analysis backward in time
• Relate primary production to marine survival, in context of other foodweb elements