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Dynamic Energy Budgets i.r.t. population effects of toxicants. Tjalling Jager Dept. Theoretical Biology. Contents. What DEB is not … What is DEB? Advantages of using DEB. Example life-cycle dataset Bindesb ø l et al (2007) copper in Dendrobaena octaedra

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contents
Contents
  • What DEB is not …
  • What is DEB?
  • Advantages of using DEB

Example life-cycle dataset

Bindesbøl et al (2007)

  • copper in Dendrobaena octaedra
  • size, survival, cocoons over 20 weeks
  • here, only [Cu] > 80 mg/kg
what deb is not
What DEB is not
  • DEB is not a population model
  • DEB is not needed to estimate population effects
deb less analysis

80

120

160

200

1

2

DEB-less analysis

40

1

35

30

0.8

25

0.6

fraction survival

cumulative reproduction

20

hatching time: 92 days

0.4

15

10

0.2

5

0

0

0

50

100

150

0

50

100

150

time (days)

time (days)

deb less analysis1

80

120

160

200

DEB-less analysis

40

1

35

30

0.8

25

0.6

fraction survival

cumulative reproduction

20

hatching time: 92 days

0.4

15

10

0.2

5

0

0

0

50

100

150

0

50

100

150

time (days)

time (days)

intrinsic rate of increase

2-stage model

splined, Euler-Lotka

1

2

Intrinsic rate of increase

0.025

0.02

0.015

population growth rate (d-1)

0.01

0.005

0

60

80

100

120

140

160

180

200

concentration (mg/kg soil)

what have we achieved
What have we achieved?
  • Integrated effects on survival and reproduction over time …
  • … for test concentrations and test conditions …
  • Can we make educated inter- and extrapolations?
  • longer exposure time,
  • untested concentrations,
  • time-varying conditions,
  • temperature,
  • food limitation,
  • other species,
  • other compounds …
what is deb

Kooijman (in press)

What is DEB?

Quantitative theory; ‘first principles’

  • time, energy and mass balance

Life-cycle of the individual

  • links levels of organisation: molecule  ecosystems

Comparison of species

  • body-size scaling relationships; e.g., metabolic rate

Fundamental to biology; many practical applications

  • (bio)production, (eco)toxicity, climate change, …

Kooijman (2000)

bookkeeping rules

feeding

reproduction

maturation

maintenance

growth

Bookkeeping rules …
toxicants in deb

internal

concentration

in time

external

concentration

(in time)

life-history

traits

Toxicants in DEB

one-compartment model, accounting for changes in body size

toxico-

kinetics

toxicants in deb1

internal

concentration

in time

DEB

parameters

in time

external

concentration

(in time)

Toxicants in DEB

ingestion rate

maintenance rate coeff.

egg costs

etc. …

toxico-

kinetics

life-history

traits

toxicants in deb2

internal

concentration

in time

DEB

parameters

in time

external

concentration

(in time)

Toxicants in DEB

KM-DEB (Klok et al, 1996)

DEBtox (Kooijman & Bedaux, 1996)

DEB3 (Jager et al, subm.)

toxico-

kinetics

DEB

model

life-history

traits

toxicants in deb3

internal

concentration

in time

DEB

parameters

in time

external

concentration

(in time)

Toxicants in DEB

growth,

time to reproduction,

reproduction rate

mortality

etc. …

toxico-

kinetics

DEB

model

life-history

traits

deb analysis of data
DEB analysis of data

Simultaneous fit size and repro data

MoA: decrease in ingestion rate

9

40

80

80

8

35

120

120

160

7

30

160

200

200

6

25

cumulative offspring per female

5

body length

20

4

15

3

10

2

5

1

0

0

50

100

150

0

50

100

150

time (days)

time (days)

deb analysis of data1

40

9

35

8

30

7

25

6

cumulative offspring per female

20

5

body length

15

4

10

3

5

2

0

0

50

100

150

1

time (days)

0

50

100

150

time (days)

DEB analysis of data

Assume size-dependent feeding limitation (Jager et al, 2005)

80

80

120

120

160

160

200

200

parameter estimates

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Parameter estimates

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

to population model …

population effects

no-effects

DEB, Euler-Lotka

Population effects

2-stage model

0.025

splined, Euler-Lotka

0.02

0.015

population growth rate (d-1)

0.01

0.005

0

60

80

100

120

140

160

180

200

concentration (mg/kg soil)

what s different
What’s different?

model

parameters

extrapolated

parameters

DEB

effects

data individuals

population

consequences

DEB-less

educated extrapolation

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

time-varying concentrations

educated extrapolation1

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

less food in environment

food limitation
Food limitation

0.025

0.02

food 100%

0.015

population growth rate (d-1)

0.01

food 90%

0.005

0

60

80

100

120

140

160

180

200

concentration (mg/kg soil)

educated extrapolation2

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

size-dependent feeding limitations

food limitation juveniles

40

9

35

8

30

7

25

6

cumulative offspring per female

20

5

body length

15

4

10

3

5

2

0

0

50

100

150

1

time (days)

0

50

100

150

time (days)

Food limitation juveniles

80

80

120

120

160

160

200

200

food limitation juveniles1

0.025

0.02

0.015

population growth rate (d-1)

0.01

0.005

0

60

80

100

120

140

160

180

200

concentration (mg/kg soil)

Food limitation juveniles

food 100%

food 90%

educated extrapolation3

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

other compounds (related)

educated extrapolation4

internal

concentration

in time

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

external

concentration

(in time)

toxico-

kinetics

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

other compounds (mixtures)

educated extrapolation5

internal

concentration

in time

metabolic

processes

in time

external

concentration

(in time)

Educated extrapolation

TK pars

tox pars

DEB pars

toxico-

kinetics

DEB

model

life-history

traits

other (related) species

what s the use of deb
What’s the use of DEB?
  • In-depth interpretation of effects on individual
    • all endpoints over time in one framework
    • indicates experimental ‘problems’
    • mechanism of action of compound
  • DEB is essential for inter- and extrapolation
    • e.g., extrapolation to field conditions
    • ‘repair’ experimental artefacts
  • Natural link with different population approaches
    • simple (e.g., Euler-Lotka and matrix models)
    • more complex (e.g., IBM’s)
slide29
But …
  • Strong (but explicit) assumptions are made
    • on metabolic organisation
    • on mechanisms of toxicity
  • Elaborate DEB models require strong data
    • growth, repro and survival over (partial) life cycle
    • e.g., Daphnia repro protocol extended with size
  • Almost every analysis raises more questions
    • difficult to perform on routine basis

Interesting point raised by DEB3 …

    • hatching time and hatchling size can be affected by stress
slide30
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Vacancies

  • PhD student, Marie Curie training network (CREAM)

Courses

  • International DEB Tele Course 2011

Symposia

  • 2nd International DEB Symposium 2011 in Lisbon

More information: http://www.bio.vu.nl/thb