Management Unit of the North Sea Mathematical Models
MUMM | BMM | UGMM
ICES CM 2012/E:17
SOLEMOD WESTBANKS
How is the connectivity of sole larvae affected by wind and temperature
changes in the Southern North Sea? A modelling approach
Geneviève Lacroix1, Gregory E. Maes2, Loes J. Bolle3, Filip A.M. Volckaert2
1. Management Unit of the North Sea Mathematical Models (MUMM), Royal Belgian Institute of Natural Sciences (RBINS), Belgium
2. Biodiversity and Evolutionary Genomics, Katholieke Universiteit Leuven (KU Leuven), Belgium
3. IMARES – Institute for Marine Resources & Ecosystem studies, The Netherlands
Introduction
Objective
Connectivity of flatfish remains an open question, especially at early life stages. The impact of
anthropogenic factors, such as climate change on larval dispersal remains unknown. The case of sole
(Solea solea) is of particular interest because sole is one of the most valuable commercial species in
the North Sea. It is important to understand how the retention/dispersal of larvae would be affected by
climate change in order to propose appropriate measures for the management of the North Sea stock.
To investigate the impact of climate change
– temperature increase and
wind magnitude/direction changes –
on the recruitment and connectivity of sole larvae
Methodology
80
Elbe
Ijssel
Eggs
Yolk larvae
First-feeding larvae
Metamorphosing larvae
f(T)
f(T)
f(HYD,MIG)
f(T)
constant
f(HYD,MIG)
f(T)
constant
f(HYD,MIG)
Vertical
migration
scheme
60
Ems Weser
Juveniles
20
NL
3.5
2.5
2.5
BE
48.5
-4
-2
52.5
BE
UK
NL
Tha
50.5
FR
1.5
FR
NL
No
BE
FR
1.5
0
2
4
6
8
48.5
-4
0
-2
0
2
4
6
8
Longitude (°E)
Longitude (°E)
10
Fig. 2. Schematic representation of the sole larvae IBM. T: Temperature,
HYD: hydrodynamics, MIG: vertical migration.
0
France
3.5
UK
GE
54.5
Settlement f(SED)
30
Seine
6
Th
EC
40
Belgium
6
50.5
GE
10
BC
52.5
56.5
16
16
10
Tx
N
50
NS Canal
Rhine
Netherlands
Meuse
Scheldt
Thames
54.5
Adults
70
Humber
UK
GB
Latitude (°N)
90
Tweed
GE
Pelagic phase, main recruitment variability
Stage duration f(T)
Mortality
f(T)
Position
f(HYD,MIG)
100
Germany
Fifth of forth
Latitude (°N)
eggs/m²/d
56.5
Spawning f(T)
3D COHERENS-NOS
Tay
In the sole larvae IBM 4 stages are considered [Fig. 2]. Eggs are released within the 6 main spawning grounds of the
North Sea [Fig. 3 left] during a 3-month period (peak of spawning at 10°C). The nurseries [Fig. 3 right] have been
defined as coastal area with a depth of < 20 m and a high proportion of sand and/or mud (< 5 % gravel).
Latitude (°N)
The sole larvae transport model
couples the 3D hydrodynamic
model
COHERENS
with
an
Individual Based Model (IBM) of
the sole larvae [1][2]. It has been
implemented in the North Sea
[Fig. 1] for the period 1995-2006.
Fig. 3. Left: main spawning grounds in the North Sea and mean number of eggs spawned. Eastern
Channel (EC), Belgian Coast (BC), Texel (Tx), German Bight (GB), Norfolk (N), and Thames (Th). Right:
nurseries. France (FR), Belgium (BE), Netherlands (NL), Germany (GE), Norfolk (No), Thames (Tha).
The sensitivity of recruitment and connectivity to climate change is assessed by estimating the impact of a
hypothetical (i) water temperature increase (+2°C) but no change of spawning period, (ii) increase of the wind
intensity (+4 %) and (iii) increase of southwesterly wind (+10 % towards East and +20 % towards North).
Longitude (°E)
Fig. 1. Geographic implementation of
the model, with bathymetry (m)
Results
EC
56.5
GE
54.5
BC
56.5
GE
54.5
The impact of climate change scenarios is assessed by comparing the trajectories of the center of mass
[Fig. 5], the transport success to the nurseries [Fig. 6] and the connectivity matrices [Fig. 7] obtained with the
standard run and the perturbed simulations (for 4 contrasted years in term of wind and temperature: 1997,
Nurseries
1998, 2005 and 2006).
56.5
UK
BE
50.5
Latitude (°N)
48.5
-4
52.5
NL
0
2
4
6
Tx
56.5
48.5
-4
8
GE
54.5
UK
2
4
6
8
GB
56.5
52.5
NL
BE
50.5
GE
-2
0
2
4
UK
NL
6
48.5
-4
8
N
GE
54.5
a
GE
54.5
NL
BE
52.5
b
Tha
FR
50.5
FR
-2
0
2
c
Relative difference (%)
4
6
8
Th
56.5
48.5
-4
GE
-2
0
2
4
Longitude (°E)
6
8
Wind magnitude +4%
SW wind increase
Temperature +2°C
FR
-0.6
-16.3
-60.5
BE
-2.5
-4.5
-68.7
NL
GE
No
Tha
-0.9
1.8
-0.7
1.2
47.7
7.4 -28.8 18.3
-74.8 -62.7 -67.1 -60.1
54.5
52.5
UK
52.5
NL
BE
50.5
0
2
4
6
8
48.5
-4
Fig. 5. Trajectories of the centre of mass (6
spawning grounds) for the 4 runs. Origin:
empty circle. End of trajectories: full circles.
NL
BE
50.5
FR
-2
UK
FR
-2
0
2
4
6
8
Longitude (°E)
Fig. 4. Final distribution of larval abundance (#
larvae) after the pelagic phase for the 6 main
spawning grounds. Mean 1995-2006. STD run.
Fr
Be
Nl
Ge
No
Tha
3
0
0
0
0
4
4
0
0
2
4
4
4
1
1
4
4
4
1
0
4
4
4
1
0
4
0
0
0
0
4
2
0
0
3
4
Th
N
GB
Tx
BC
EC
No
BE
50.5
FR
56.5
48.5
-4
0
54.5
52.5
48.5
-4
# larvae
FR
-2
Standard
Wind magnitude +4%
SW wind increase (+10% East, +20% North)
Temperature +2°C
NL
BE
50.5
FR
-2
UK
Latitude (°N)
52.5
Fig. 6. Recruitment in the 6 nurseries (mean 4 years). The error
bars are the stdev due to interannual variability. The table gives
the relative difference between perturbed and standard runs.
- Larval retention in nurseries decreases significantly with temperature increase
due to a combination of stage duration reduction and higher egg and yolk
larvae mortality [Fig. 6]. The travel distance is reduced [Fig. 5].
- Recruitment decreases or increases when wind is perturbed [Fig 6]. The travel
distance increases with SW wind increase [Fig. 5].
- New connections appear and others disappear according to the scenario and
the area considered [Fig. 7].
d
3
0
0
0
1
4
4
0
0
2
4
4
4
1
1
4
4
4
1
0
4
4
4
1
0
4
0
0
0
0
4
2
0
0
4
4
Th
N
GB
Tx
BC
EC
3
0
0
0
0
4
4
0
0
0
4
4
4
2
0
4
4
4
2
0
4
4
4
2
0
4
0
0
0
0
4
1
0
0
3
4
Th
N
GB
Tx
BC
EC
3
0
0
0
2
4
4
0
0
2
4
4
4
0
0
4
4
4
0
0
4
4
4
0
0
4
0
0
0
0
4
1
0
0
3
4
Th
N
GB
Tx
BC
EC
Spawnig grounds
The dispersal pattern at the 6 main
spawning grounds is shown in Fig. 4.
Fig. 7. Connectivity matrices. #years
where connection or retention (selfrecruitment) is predicted by the model. A:
standard run, b: wind intensity increase, c:
SW wind increase, d: temperature
increase. A: Frequency of connections:
never (red), sometimes or often (yellow),
always (green). B-d: more connections
(blue), less connections (orange).
Conclusions & Perspectives
- The impact of T° increase (without modification of spawning period) is a reduction of
recruitment at all nurseries.
- A modification of the wind (intensity increase/southwesterly increase) gives either a
reduction or an increase of recruitment according to the nurseries.
- The impact of climate change scenarios predicted by the model is significant (T°) and
not negligible (wind) but interannual variability due to meteorological forcing is high.
Acknowledgements:
This work has been carried out in the framework of the SOLEMOD & WESTBANKS
projects, funded by the Belgian Science Policy Office (BELSPO).
http://www.mumm.ac.be/
PERSPECTIVES:
- The IBM is still under development.
We will focus on mortality by including
a prey/predator field.
- The dispersal pattern of larvae and
recruitment must be validated.
REQUEST:
We are looking
for life-history
data of sole to
validate the
model
References:
[1] Savina M., Lacroix G., Ruddick K., 2010. Modelling the transport of common sole larvae in the Southern North Sea:
influence of hydrodynamics and larval vertical movements JMS, 81: 86-98.
[2] Lacroix G., Maes G.E., Bolle L.J., Volckaert F.A.M. 2012. Modelling dispersal dynamics of the early life stages of a
marine flatfish (Solea solea L.). JSR, in press. 10.1016/j.seares.2012.07.010
G.Lacroix@mumm.ac.be