Dynamics of lipid storage in marine - PowerPoint Presentation

Slide1

Dynamics of lipid storage in marine copepodsand its consequences for effects of oil pollution

Tjalling Jager & Bjørn Henrik Hansen

DEB symposium, May/June 2017Slide2

ContextEnergyBar project (RCN-funded)Effects of produced water on copepodsTools for ERA offshore

petroleum activities

Calanus finmarchicusSlide3

ContextFocus on lipid storageCapture its dynamics in a DEB context?Effects on accumulation/toxicity of chemicals?Slide4

Calanus life cycle

egg N1 N2 N3 N4 N5 N6 C1 C2 C3 C4 C5 C6

Acceleration of growth after metamorphosisAbrupt stop of growth after final moult

acceleration

non-feeding embryo/naupliusbirthadultadulthoodcopepoditefeeding naupliusmetamorphosisSlide5

Calanus life cycle

egg N1 N2 N3 N4 N5 N6 C1 C2 C3 C4 C5 C6

non-feeding embryo/naupliusLipids clearly visible from C3 onwards:increases over C3-C5decrease in adults

acceleration

birthfeeding naupliusadultadulthoodcopepoditepubertylipid build-up

treat as ‘reproduction buffer’metamorphosisSlide6

Calanus life cycleModel design:use one switch for acceleration and pubertydepart from reserveless model (‘DEBkiss’)

treat lipid storage as reproduction bufferdifferent scheme for adults (no kappa rule)stop growth at size limit

egg N1 N2 N3 N4 N5 N6 C1 C2 C3 C4 C5 C6

non-feeding embryo/nauplius

acceleration/pubertybirthfeeding naupliuscopepoditeadultadulthoodlipid build-upJager et al (2017), Mar BiolSlide7

Model fit (data Campbell et al, 2001)structure

structure+storage

temperaturesfood levels

Jager

et al (2017), Mar BiolSlide8

We’re not there yet …Open issues:maintenance estimated from respirationeffect temperature/food on final size descriptivehigh maturity maintenance to capture food limitationenergetics of gonad maturation requires attention

rules for allocation to eggs unclearSlide9

We’re not there yet …Open issues:maintenance estimated from respirationeffect temperature/food on final size descriptivehigh maturity maintenance to capture food limitationenergetics of gonad maturation requires attention

rules for allocation to eggs unclearSlide10

We’re not there yet …Open issues:

maintenance estimated from respirationeffect temperature/food on final size descriptivehigh maturity maintenance to capture food limitationenergetics of gonad maturation requires attentionrules for allocation to eggs unclearSlide11

Lipids and toxicantsHydrophobic chemicals high affinity for wax estersEffect lipid on uptake/elimination and toxicity?focus on survival (GUTS-SD or DEBtox-survival)

lipid poor

lipid richSlide12

Lipids and toxicantsCan lipids explain differences between experiments?

10

2

10

3

0

0.2

0.4

0.6

0.8

1

external concentration (THC,

µ

g/L)

fraction surviving

CD

M

D

lipid rich

lipid poor

Hansen

et al (

2016), JTEHSlide13

Lipids and toxicantsCan lipids explain differences between experiments?‘Survival of the fattest’ (Lassiter & Hallam, 1990):two compartments to represent individualassume fast internal redistribution

Hansen

et al (2016), JTEHSlide14

Lipids and toxicantsCan lipids explain differences between experiments?‘Survival of the fattest’ (Lassiter & Hallam, 1990):two compartments to represent individualassume fast internal redistribution

fatter individuals take longer to reach steady state

Hansen et al (2016), JTEHhowever, in this case …

insufficient difference in lipid contentno shift in lipid content survivors over treatments

increasing lipid contentSlide15

Case: dimethylnaphthalene Survival and body residues over timedo not assume that lipids are fastmortality linked to concentration in ‘structure’

submitted: Jager et al …Slide16

Case: dimethylnaphthalene Survival and body residues over timedo not assume that lipids are fastmortality linked to concentration in ‘structure’

lipids are very slow …submitted: Jager

et al …

0

2

4

6

time (days)

0

0.2

0.4

0.6

0.8

1

s

u

r

v

i

v

a

l

p

r

o

b

a

b

i

l

i

t

y

0

2

4

6

8

time (days)

500

1000

1500

2000

2500

3000

i

n

t

e

r

n

a

l

c

o

n

c

.

,

t

o

t

a

l

(

µ

m

o

l

/

k

g

)

0 µM

1.03 µM

1.97 µM

4.83 µM

10.3 µM

29.3 µM

1.2 µMSlide17

Case:

dimethylnaphthalene

time

internal concentration

total body

time

internal concentration

structure

Simulate effect of different lipid content

submitted:

Jager

et al …Slide18

Case: dimethylnaphthalene

time

internal concentration

structure

toxicity

Simulate effect of different lipid content

Limited effect on toxicity

submitted:

Jager

et al …

0

2

4

6

8

10

time (days)

0

5

10

15

LC50 (µM)Slide19

Difference toxicity life stages

No effect lipid content … but several stages differ …

Jager et al (2016) ETCSlide20

ConclusionsLipids play important role in life cycle and toxicitystorage dynamics like ‘repro buffer’lipids affect toxicokinetics, limited effect on toxicitydifferences in sensitivity not explained by lipids …

maternal transfer and secondary poisoning?Slide21

ConclusionsLipids play important role in life cycle and toxicitylipid storage functions like ‘repro buffer’lipids affect

toxicokinetics, limited effect on toxicitydifferences in sensitivity not explained by lipids …

maternal transfer and secondary poisoning?Mechanistic models increase understandingfirst version of DEBkiss Calanus modelGUTS-SD works well for survival dataSlide22

ConclusionsLipids play important role in life cycle and toxicitylipid storage functions like ‘repro buffer’lipids affect

toxicokinetics, limited effect on toxicitydifferences in sensitivity not explained by lipids …

maternal transfer and secondary poisoning?Mechanistic models increase understandingfirst version of DEBkiss Calanus

modelGUTS-SD works well for survival dataPredictive tools for the field situation?Slide23

FundingEnergyBar 225314/E40Project output: www.debtox.nl/projects/project_energybar.html

More informationon DEBtox/GUTS: www.debtox.info

summercourse dynamic modelling of toxic effects, August 2018 (DK)