FLEX Station

58°55’N 0°30’E

Depth: 135 m

ICES CM 2010/L:40

27

26

ECOHAM4 - carbon cycle

smalldetritus

carbonateshells(living)

DIC

carbonateshells

(dead)

benthiccalcite

labileDOC semilabile

DOC

1

2

4 Bacteria

largedetritus

6

9

1011

12

13

5

1415

1617

25

2122

18

3

carbonate

system:

CO

CO

HCO

B(OH)

OH

alkalinity

pH

2

3

4

3--

-

-

-

surface

20

2020

bottom

19

28

28 27

27

29diatoms

flagellates

benthicdetritus

microzoo-plankton

mesozoo-plankton

structuredzooplankton

adult

structuredzooplankton

egg-N2

structuredzooplankton

N3-N6

structuredzooplankton

C1-C3

structuredzooplankton

C4-C5

715

For this study the 3D ecosystem model ECOHAM4 has been coupled

to a stage-structure population model parameterised for

according to Stegert 2007. The copepod model includes ten state

variables within five life stages, one for abundance and biomass each.

Carbon-, nitrogen- and phosphors-cycles are each calculated explicitly.

P.elongatus

et al.

The ModelMotivation

The Simulation

Simulations were run for the Northwestern European Continental Shelf (NERC) using

realistic meteorological and hydrographic conditions. To compare the simulated

seasonal zooplankton population dynamics two example stations, one for the

southern North Sea (GLOBEC-Station 32) and one for the northern North Sea (FLEX-

Station), are presented.

Seasonal zooplankton dynamics in the southern and

northern North Sea captured by ecosystem and

stage-structured population models

Christian Lindemann * , Andreas Moll²1,2

,

1) Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany

2) Institute of Oceanography, University of Hamburg, Hamburg, Germany

3) Institute for Coastal Research, GKSS-Forschungszentrum, Geesthacht, Germany

*Corresponding author: , Tel.: +49 40 42838 5656

Markus Kreus³

christian.lindemann@uni-hamburg.de

GLOBEC Station 32

54°40’N 7°00’E

Depth: 38 m

GLOBEC 32-StationResults

0

1

2

3

4

5

1 51 101 151 201 251 301 351

Time [days]

Bio

mas

s[m

gC

/m³]

Adults

CIV - CV

CI - CIII

NII - NVI

egg - NII

0

1

2

3

4

5

1 51 101 151 201 251 301 351

Time [days]

Bio

mas

s[m

gC

/m³]

Adults

CIV - CV

CI - CIII

NII - NVI

egg - NII

0

5

10

15

20

25

1 51 101 151 201 251 301 351

Time [days]

Bio

mas

s[m

gC

/m³]

Adult

CIV - CV

CI - CIII

NIII - NVI

egg - NII

0

5

10

15

20

25

1 51 101 151 201 251 301 351

Time [days]

Bio

mas

s[m

gC

/m³]

Adult

CIV - CV

CI - CIII

NIII - NVI

egg - NII

Discussion & Outlook

Fig. 1: Carboncycle as implemented in ECOHAM4 incl. Stage-structured population model

Fig. 6: Modeled structured zooplankton abundance at FLEX-Station

Fig. 3: Modeled zooplankton biomass at GLOBEC 32-Station

Fig. 5: Modeled stage-resolved structured zooplankton biomass at GLOBEC 32-StationFig. 4: Modeled stage-resolved structured zooplankton biomass at FLEX-Station

FLEX-Station

Fig. 2: Modeled zooplankton biomass at FLEX-Station

Fig. 7: Modeled structured zooplankton abundance at GLOBEC 32-Station

Preliminary model results indicated, that general

zooplankton dynamics and the seasonal population

dynamics of in the northern and southern

North Sea vary significantly, mostly due to different

hydrological condition.

The northern area being stratified during summer,

exhibited two peaks in zooplankton biomass, correlating

to spring and autumn phytobloom.

For the southern area the zooplankton biomass peaked

at the end of July. This peak was more pronounced in

the “bulk” formulation than in structured zooplankton,

indicating the different behavior of the respective model

compartments.

Overall zooplankton biomass in the northern North Sea

was estimated to be approx. five times as high as in the

southern North Sea.

For the FLEX- position the model calculated four

generations per year, while shortened generation time

for the southern North Sea lead to five generations.

P. elongatus

References!

!

!

!

Corkett, C.J. & McLaren, I.A. (1978) The biology of Pseudocalanus; Advances in Marine Biology; 15, 1-231.

Harris, R.P. and Paffenhöfer, G.-A.(1976) The effect of food concentration on cumulative ingestion and growth efficiency of two small marine planktonic copepods; Journal of the Marine Biological Association of the United Kingdom; 56: 875-888.

Renz, J., Mengedoth, D. and Hirche, H.-J. (2008) Reproduction, growth and secondary production of Pseudocalanus elongatus Boeck (Copepoda, Calanoida) in the southern North Sea; Journal of Plankton Research; 30(5): 511-528.

Stegert, C., Kreus, M., Carlotti, F., Moll A. (2007) Parameterisation of a zooplankton population model for Pseudocalanus elongatus using stage durations from laboratory experiments; Ecological modelling 206; 213230.

The seasonal zooplankton dynamics of marine systems are characterized by a few

key players. In the North Sea one of these species is

(Boeck, 1865), a calanoid copepod displaying different seasonal dynamics in

northern and southern areas of that ecosystem.

Those population dynamics are possibly best captured by models using an explicit

approach of structured population as opposed to merely a “bulk” zooplankton

formulation.

The strong influence of physical properties on plankton ecology put forward the

importance of spatially-explicit models, especially in the light of changing

environmental conditions, such as climate change.

Thus, a combined approach is likely to give better and more holistic representation

of zooplankton population dynamics.

Pseudocalanus elongatus

The model displayed differences between the “bulk” and stage-structured formulation not only in relative biomass, but also in dynamic

behavior.

In general the structured population model appears to be an appropriate tool for the investigation of specific populations.

The trade-off however, is a higher model complexity and computational costs. Autumn production still seems to be overestimated by the

stage-structured model. Thus improvement towards this end and the inclusion of adaptive capabilities would further strengthen this model.

The modeled zooplankton biomass (Harris & Paffenhöfer, 1976), as well as the numbers of generations predicted by the

structured population model (Corkett & McLaren, 1978; Renz et al., 2008), was within the range of observed values described in literature.

Acknowledgements

We are thankfull for the help and advice

from Ina Lorkowski, Myron Peck

and Johannes Pätsch.

Funding for the research was received

from the DFG funded AQUASHIFT

project via the"RECONN" project

as well as the CliSAP Cluster of Excellence.

This poster presentation is supported

by a ICES travel fund for early-career

scientists.

.