Modelling the impact of changes in the physical environment on plankton succession with special emphasis on Daphnia-algae interactions

Frank Peeters & Dietmar StraileFrank Peeters & Dietmar StraileLimnological Institute, University of Konstanz Limnological Institute, University of Konstanz

MOPPS

NAO

Local Meteorology

Water Temperature

Daphnia growth and biomass

Daphnia grazing

Timing of the clear-water phase

-2

-1

0

1

2

3

NAO-Index-4 -2 0 2 4 6

Mea

n A

ir Te

mpe

ratu

re

(Dec

.-Mar

ch) [

°C]

r = 0.62,p < 0.01

4

1

2

3

7 8 9 10 11 12

WaterTemperature inMay [°C]

log

(

biom

ass

in M

ay)

[mg

C/s

qm]

10D

aphn

ia

r = 0.73,p < 0.005

130

140

150

160

170

180

1 2 3 4

Star

t cl

ear-

wat

er p

hase

[julia

n da

y]

log ( biomass in May) [mg C/sqm]

10 Daphnia

r = -0.84p < 0.0001

130

140

150

160

170

180

-3 -1 1 3 5

NAO-Index

Star

t cl

ear-

wat

er p

hase

[julia

n da

y]

r = -0.55p < 0.05

Influence of climate variability on planktoninteractions

Straile et al. (2003)

Clear-water timing in Central European lakes

120

140

160

180

200

1970 1980 1990 2000-6-4-2024

NA

OIndex

W

n = 136, from 28 lakes

Straile (2002)

Cle

ar-w

ater

timin

g[ju

lian

day]

Daphnia growthsensitive to water temperature

Phytoplankton growth in springsensitive to light (mixing) conditions

water temperatures increase

Daphnia growth occurs earlieralgae growth rate unchanged

light conditions (mixing) remain unchanged

Anticipated effect of climatic warmingfor deep monimictic lakes in spring

Shift in ecosystem interactions

mix

is

mix

is

mix

is

Impact of climatic change

Straile (2000)

Models

1) 1-dimensional vertical mixing model

Peeters et al. 2002

Comparison of simulated and measured temperatures

Peeters et al. 2002

Comparison of simulated and measured temperatures

Models

1) 1-dimensional mixing model ( )2) Algae-growth model

(dependent on solar radiation, diffusivities and water temperatures)

3) Daphnia – model(different complexities)

a. biomass modelb. size-structured dynamic modelc. different parameterizations of growth and

reproduction rates

Modelling the impact of environmental conditions on plankton succession

1. Development of a dynamic algae-Daphnia model including physical transport

dept

h (z

)Algae(z)

, K (z)zT(z)

( )

max

max( )( ) ( , ) ( )

( ) ( ) ( , )b

b bs

s

g nn d nt s

n s s 0g s n t s b t

b t s n t s dsβ

∂ ⋅∂= − − ⋅

∂ ∂> =

⋅ =

= ⋅ ⋅∫

1D-vertical diffusion model considering algae growth and heat flux

size (s)

size structured dynamic Daphnia growth model(1D-advection in size)

dept

h (z

)Algae(z)

, K (z)zT(z)

( )

max

max( )( ) ( , ) ( )

( ) ( ) ( , )b

b bs

s

g nn d nt s

n s s 0g s n t s b t

b t s n t s dsβ

∂ ⋅∂= − − ⋅

∂ ∂> =

⋅ =

= ⋅ ⋅∫

1D-vertical diffusion model considering algae growth and heat flux

size (s)

size structured dynamic Daphnia growth model(1D-advection in size)

2. Simulating the effects of temporal variation in environmental conditions from late winter/spring to early summer in Lake Constance

Calibration and validation of the models based on field data

Measurements of temperature and fluorescence with high temporal resolution

Calibration and validation of the models based on field data

… with long-term data of Daphnia abundances and size distributions

0

20

40

60

80

100

79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

% D

aphn

iasi

zecl

ass

Measured size class distribution of Daphnia from 1979 - 1998

0

20

40

60

80

100

79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

% D

aphn

iasi

zecl

ass

Measured size class distribution of Daphnia from 1979 - 1998

1. Development of the model(s)

2. Calibration and validation of the model based on field data (Lake Constance)

- existing long term data set - data collected specifically during this project

(temporal resolution, data quality)

3. Investigation of the effect of model refinement (Daphnia sub-models) on overall model performance

4. Assessment of the impact of changes in the physicalenvironment on plankton succession in Lake Constance using hypothetical warming scenarios

Tasks