26-10-2010

Or in other words:

Is maintaining a sustainable ecosystem = maintaining ecosystem stability? Gideon Gal and Arkadi Parparov Kinneret Limnological Laboratory Israel Oceanographic and Limnological Research

Objectives

if pushed further: is sustainability=stability?

Road map

External forcing or Management measures

 Ecosystem sustainability and stability- are they the

same?  Ecosystem models as a research and management tool  When do abrupt changes occur?  What are the acceptable limits for management measures?  Examples of the effectiveness of an ecosystem model

to examine beyond observation limits  Use of an ecosystem model run in long-term scenario mode

DYCD

Ecol. thresholds Tipping points

Resistance Resilience

WQI & CWQI

Sustainability limits

Stability limits

? Stability = Sustainability

1

26-10-2010

Lake Kinneret

Lake Kinneret uses

Mediterranean Sea

Recreation and tourism

Drinking water

Altitude (m asl) -210 Surface area (km2) 170 Max. Length (km) 22 Avg. Depth (m) 24 Max. Depth (m) 43 Prim. Prod. (gC m-2 y-1) 640

Dead Sea

(WQIs) for Lake Kinneret (Hambright et al 2000)  Underlying assumptions:  1970-1991: serves as a reference period for which

acceptable ranges for ecosystem variables were defined in order insure sustainability

 All WQI’s were merged into a composite water quality

index (CWQI) (Parparov & Hambright 2007)

100

250

100

80

240

80

60 40 20 0 100

Rating [Cl], %

 Can be defined based on set of water quality indices

WQI approach [Cl-], mg L-1

Ecosystem sustainability

D. Markel

Rating [Cl]

http://earthobservatory.nasa.gov

230 220 210

200

250

300

350

[Cl-], mg L-1

R = f[Cl]

Expert panel (DELPHI Method)

40 20

200

150

60

0 0

1

2

3

4

5

WLL, below -208.0 m

[Cl] = F(WLL)

0

5

10

15

WLL, below -208.0 m

R = V(WLL)

Model Limnological studies

2

26-10-2010

Permissible ranges

WQI Rating curves (Winter-spring)

Management Measures or External forcing

CWQI Permissible Range

Nitrogen load (gm-2y-1)

?
Phosphorus load (gm-2y-1)

?
Water level (m above sea level)

?
Methodologically: CWQI = F(MM)

Defining ecosystem stability 

DYCD Coupled model system Input data

DYRESM

1D

CAEDYM

Chem + Biol

Output

Lake mean value for each layer/ day/variable: ToC, WL, N, P, DO,

Meteorology In & outflows (vol, contents)

Food-web components

Physical Initial conditions

Equation parameters Biogeochemical initial conditions

DYRESM = Dynamic Reservoir Model CAEDYM = Computational Aquatic Ecosystem Dynamics Model.

DYCD

3

26-10-2010

CAEDYM configuration

Management measures scenarios  20-40 year DYCD simulations (2000-2039)  Loading varied over 2 orders of magnitude (x0.1-x10)  x1 scenario based on data from year 2000  Variations in N, P and N&P loading  Stable conditions or 5-10 y perturbation period  No inter-annual variation in other forcing data  Last 3-yrs of simulation used

N loading scenarios 30 25 x0.1

N Load (g/m2/y)

State variables • Physics: 6 • Chemistry: 12 • Biology: 19 • Additional derived: 21

20 15

x0.2 x0.5 x1 x2 x5

10

x10

5 0

Gal et al 2009

Sustainable management (winter-spring)

MODELLING EXPERIMENTS Management Measures: P load, N load

0.1 0.01 2

3

4

5

6

-212

0.1

0.1

2

3

4

5

6

-208

-212

0.1 -216

1

7

2

3

4

5

6

7

Scenarios

Scenarios

Scenarios

WL

-210 m

1

0.01

-216

1

7

Nload

10

-208 1

0.01

-216

1

Pload

Pload

-210 m

1

WL

-212

WL

1

WL

10

-208

N&Pload

N&P load

Nload

Nload

1

N&Pload

WL

-210 m

WL

Pload

NPload Scenario

Nload Scenario

Pload Scenario 10

100 WS

100

SA

WQI = f(MM)

60

CWQI

Rating of [TN]

80

40 20 0 0

20

40

Nload, g m-2 yr-1

60

CWQI = F(MM)

60

20 0

30

60 -2

Nload, g m yr

-1

4

26-10-2010

20

-1

yr Nload, g m

-2

Nload, g m yr

-1

30

Sustainable management policy: %Cyanobacteria 80 -2

Sustainable Management Policy: CWQI

10

0

0 0

0.4

0.8

1.2 -2

Pload, g m yr

1.6

0

2

5 CWQI

40

1

20

Resistance

Resistance

2

80

0.6

60

0.4

40

CWQI

60

CWQI

0.8

CWQI

3

NX01

100.0 100 Resistance

80

-2

yr

1.5

-1

20 yr loading scenarios- %cyano

Resistance

4

1

Pload, g m

1

100

0.5

-1

Stability (resistance) vs sustainability

80.0

60.0

60.0

40.0

40.0

20.0

20.0

0.0

0.0 2010

0.2

PX01

100.0

80.0

2012

2014

2016

2018

2010

2012

2014

2016

2018

20

N scenario

0 NP scenario 0.1

40

0 1

Load multiplication factor

10

0

0 0.1

1

10

Stability: what tips the system?

Load multiplication factor

5

26-10-2010

20 yr loading scenarios- %cyano NX02

100.0

PX02

100.0

20 yr loading scenarios- %cyano NX05

100.0

80.0

80.0

80.0

80.0

60.0

60.0

60.0

60.0

40.0

40.0

40.0

20.0 0.0 2010

2012

2014

2016

2018

40.0

20.0

20.0

20.0

0.0

0.0 2010

2012

2014

2016

2010

2018

PX05

100.0

2012

2014

2016

2018

0.0 2010

2012

2014

2016

2018

Stability: what tips the system?

Stability: what tips the system?

20 yr loading scenarios- %cyano

20 yr loading scenarios- %cyano

NX1

100.0

PX1

100.0

NX2

100.0

80.0

80.0

80.0

60.0

60.0

60.0

60.0

40.0

40.0

40.0

20.0 0.0 2010

2012

2014

2016

2018

40.0

20.0

20.0

20.0

0.0

0.0 2010

2012

Stability: what tips the system?

2014

2016

2018

PX2

100.0

80.0

2010

2012

2014

2016

2018

0.0 2010

2012

2014

2016

2018

Stability: what tips the system?

6

26-10-2010

20 yr loading scenarios- %cyano NX5

100.0

PX5

100.0

20 yr loading scenarios- %cyano NX10

100.0

80.0

80.0

80.0

80.0

60.0

60.0

60.0

60.0

40.0

40.0

40.0

20.0 0.0 2010

2012

2014

2016

20.0

0.0

0.0

2018

40.0

20.0

20.0

2010

2012

2014

2016

2018

2010

2012

2014

Stability: what tips the system?

Nscen

0.0

2018

2010

2012

2014

2016

2018

Resilience

Pscen

25

50% Time to return (y)

40% %Cyano

2016

Stability: what tips the system?

%Cyano vs (TN/TP)loads; Lake (1980-2008) and model Lake

PX10

100.0

30% 20% 10% 0%

20 15

TN winter

10

TN summer 5 0

0

40

80

120

160

0.1

0.2

0.5

1

2

5

7.5

10

Load multiplication factor

(TN/TP)load

7

26-10-2010

Cyanobacteria, % in algal biomass

Conclusions  Sustainability: limits for management measures (e.g.

nutrient loading) have been defined (Gal et al. 2009)  Stability: Response to management measures were not

trivial  …Ecosystem stability limits ≠ sustainability limits  Therefore, measures that allow sustaining an ecosystem

will not necessary ensure stability or vice versa  However, clear definitions of ecosystem stability and relationship with management measures are still required  The results represent some of the potential that can be found in ecosystem models, but are not always utilized

25 20 15 10 5 0 1990

1994

1998

2002

2006

Winter-Spring, 1969-2007 Winter-Spring, 1969-2008

2.5

3.5

2.0

3

1.5 Residuals

Shannon Index

2.5

2

1.5

1.0 0.5 0.0 -0.5

1

-1.0 0.5

0 1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

-1.5 1960

1970

1980

1990

2000

2010

8

26-10-2010

0.50

2.0 Pload

Shannon Index

Nload

1.0

0.25

WS

0.0

SA

0.00 0.1

1

10

0.1

N&Pload, multipl factor

Lake Kinneret WQI

L-1

Total suspended solids, mg (TSS) Total nitrogen, mg L-1 (TN) Total phosphorus, µg L-1 (TP) Primary production, g C m-2 d-1 (PP) Chlorophyll, µg L-1 (Chl) Cyanobacteria, % total biomass (%Cyano) Biomass of Zooplankton, g m-2 (Bzp)

WinterSpring 1.0-7.1 0.3-1.2 9-38 1.1-3.2 5.5-40.5 0-3.7

SummerAutumn 0.6-4.1 0.2-0.9 5-28 0.7-2.2 1.5-10.1 1-10.8

13-52

7-37

CWQI= weighted sum of WQI’s; 0 < CWQI ≤ 100 Acceptable range: 60 ≤ CWQI

10

Semiannual avg, Summer-Autumn, 1969-2008

Permissible ranges for ecosystem variables Water quality indices (WQI)

1 [NP]load, multiplication factor

60

%cyano

Phyto-biomass, rel. units

N&Pscen, PhytoBiom, normalized

30

0 1969 1974 1979 1984 1989 1994 1999 2004

9

26-10-2010

x0.1Nload&Pload, %Cyano

x10Nload&Pload, %Cyano 120.0

100.0 x10Nload x0.1Nload

x10Pload

x0.1Pload

90.0 100.0 80.0

80.0

70.0

%Cyano

50.0

60.0

40.0 40.0 30.0

20.0 20.0 10.0

0.0

0.0

Stability EV limits

Managing ecosystem stability% Cyanobacteria

Stability limits Resistance

%Cyano

60.0

ecosystem Management measures

WQ/sustainability

EV

40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 -2 -4 0.1

NP scenario

Resistance

1

10

Load multiplication factor

WQsustainability limits

10

26-10-2010

40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 -2 -4 0.1

100

NP scenario

80 Resistance % Cyano

60 40

%Cyano

Resistance

Managing ecosystem stability% Cyanobacteria

20 1

10 0

Load multiplication factor

11