Lake Washington and the synergy between long-term monitoring and experimental research

Stephanie E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Can we characterize food web interactions based on monitoring data?

• History of L. Washington

• Experimental work

• Compare expt’l results to structure of long-term data

•Multivariate Autoregressive models (MARs)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Photo: John J. Gilbert

Lake Washington

Seattle

Lake Washington

• Clearcut watershed 1800’s• 1.4 million in watershed• Fisheries & tributary manipulations• Municipal sewage until 1968

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Lake Washington

Seattle

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

86420

Secc

hi (

m)

Water clarity

Sewage diversion“Recovered”

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

0

2

4

6

Dap

hnia

L-1

86420

Secc

hi (

m)

“Recovered”Daphnia establishment

Water clarity

Sewage diversion

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

0

2

4

6

Dap

hnia

L-1

Daphnia

• Influential grazer

• Predators’ favorite

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Why the sudden Daphnia appearance?

0

2

4

6

Dap

hnia

L-1

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Why the sudden Daphnia appearance?

Neomysis

0

2

4

6

Dap

hnia

L-1

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Why the sudden Daphnia appearance?

Longfin smeltNeomysis

0

2

4

6

Dap

hnia

L-1

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Why the sudden Daphnia appearance?

Oscillatoria

Longfin smeltNeomysis

0

2

4

6

Dap

hnia

L-1

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Infante & Abella1985

Experimental evidence for Oscillatoria negative effects

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Experimental evidence for Oscillatoria negative effects

Infante & Abella1985

010002000300040005000

0 100 200 300 400Oscillatoria/ml

Cryp

tom

onas

/ml

Infante & Litt1985

Experimental evidence for Oscillatoria negative effects and Cryptomonas importance

0

400

800

1200

Asteri

onella

Fragila

ria

Melosira

Steph

anod

iscus

Tabella

ria

Chlorel

la

Cryptom

onas

Dap

hnia

pul

icar

ia b

iom

ass

(ug)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Evidence for these relationships in natural data?

0

5

10

15

0 5 10 15

0

1

2

3

4

0 5 10 15ln Oscillatoria biovolume

ln C

rypt

omon

ad b

vln

Dap

hnia

ind

L-1

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Lake Washington food web

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Multispecies Autoregressive Models (MARs)

Log abundance of species i tomorrow

Log abundance of species i today

Species-specific constant

xi(t+1) = xi(t) + ai + [bi,j xj(t)] + [ci,k uk(t)]

Ives, Dennis, Cottingham, & Carpenter. 2003. Ecol. Monogr. 73(2)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Multispecies Autoregressive Models (MARs)

Log abundance of species i tomorrow

Log abundance of species i today

Species-specific constant Log abundance

of species j today

Effect of species j on species i

xi(t+1) = xi(t) + ai + [bi,j xj(t)] + [ci,k uk(t)]

Ives, Dennis, Cottingham, & Carpenter. 2003. Ecol. Monogr. 73(2)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Multispecies Autoregressive Models (MARs)

Log abundance of species i tomorrow

Log abundance of species i today

Species-specific constant Log abundance

of species j today

Effect of species j on species i

Effect of environmental variable k on species i

Level of environmental variable k today

xi(t+1) = xi(t) + ai + [bi,j xj(t)] + [ci,k uk(t)]

Ives, Dennis, Cottingham, & Carpenter. 2003. Ecol. Monogr. 73(2)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Multispecies Autoregressive Models (MARs)

•Monthly data from 1962 to 1994

• Fit equations simultaneously for each of 13 phyto- and zooplankton groups

• Coefficients represent interaction strength

xi(t+1) = xi(t) + ai + [bi,j xj(t)] + [ci,k uk(t)]

Ives, Dennis, Cottingham, & Carpenter. 2003. Ecol. Monogr. 73(2)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Multispecies Autoregressive Models (MARs)

•Monthly data from 1962 to 1994

• Fit equations simultaneously for each of 13 phyto- and zooplankton groups

• Coefficients represent interaction strength

• Build10,000 random models – select best fit (AIC)

•Bootstrapping for confidence intervals

xi(t+1) = xi(t) + ai + [bi,j xj(t)] + [ci,k uk(t)]

Ives, Dennis, Cottingham, & Carpenter. 2003. Ecol. Monogr. 73(2)

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

MAR food web construction for Lake Washington

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

0204060

1962 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994

0

500000

1000000

1962 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994

Bio

volu

me

# L-1

Daphnia

Cryptomonads

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

• Aspects of historical conceptual model supported

• Inhibitory role of Oscillatoria• Intense competitive effects of Daphnia

• “New” relationships• Cryptomonad importance• Role for picoplankton

MAR food web construction for Lake Washington

Hampton, Scheuerell & Schindler 2006S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Explore the scale of effects!

Hampton & Schindler 2006

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Explore the scale of effects!

S. E. Hampton, NCEAS, UCSB, hampton@nceas.ucsb.edu, 7 July 2007

Weekly

Biweekly

Monthly

Hampton & Schindler 2006