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Effects of mass mortality events on food web dynamics Øystein Langangen 1,*, Ohlberger, J.1,2, S8ge, L.C. 1, Durant, J.M. 1, Ravagnan, E.3, Stenseth, N.C. 1, Hjermann, D.Ø.1,4
1) Centre for Ecological and Evolu4onary Synthesis (CEES), Department of Biosciences,University of Oslo, Norway 2) School of Aqua4c and Fishery Sciences, University of Washington, SeaHle, WA 98195, USA 3) Interna4onal Research Ins4tute of Stavanger, IRIS Environment, Postbox 8046, 4068 Stavanger 4) Norwegian Ins4tute for Water Research (NIVA), Gaustadalléen 21, N-‐0349 Oslo
2. Important species and interac4ons in the Barents Sea ecosystem
1980 1990 2000 2010Years
-4
-2
0
2
4
Krill
1980 1990 2000 2010Years
-4
-2
0
2
4
Krill
1980 1990 2000 2010Years
-3
-2
-1
0
1
2
3
Capelin
1980 1990 2000 2010Years
-3
-2
-1
0
1
2
3
Capelin
1980 1990 2000 2010Years
-4
-2
0
2
4
Calanus
1980 1990 2000 2010Years
-4
-2
0
2
4
Calanus
1980 1990 2000 2010Years
-3
-2
-1
0
1
2
3
Cod
1980 1990 2000 2010Years
-3
-2
-1
0
1
2
3
Cod
4. Time-‐series data (diamonds) and model predic4ons (grey shades) for the four dynamically modeled species. 3. Gompertz process model describing
the dynamics of the system.
1. The Barents Sea is situated north of Norway and Russia
E-‐mail: [email protected]
5. State-‐space model output: joint posterior distribu4on
6. Scenario: Fish popula4on impact as a result of 50 % reduc4on in Krill biomass in a single year
Calanus
Krill
Capelin
Cod
Productivity Calanus Krill Capelin Cod Herring SST Fishing
-1.0-0.5 0.0 0.5 1.0Posterior values
Den
sity
a Cal
-1.0-0.5 0.0 0.5 1.0
Den
sity
a Krill
-0.4-0.2 0.0 0.2 0.4
Den
sity
a Cap
-0.4-0.2 0.0 0.2 0.4
Den
sity
a Cod
-1.0-0.5 0.0 0.5 1.0Posterior values
b Cal
-1.0-0.5 0.0 0.5 1.0
c Cap,Cal
-1.0-0.5 0.0 0.5 1.0Posterior values
b Krill
-1.0-0.5 0.0 0.5 1.0
c Cap,Krill
-1.0-0.5 0.0 0.5 1.0Posterior values
c Cal,Cap
-1.0-0.5 0.0 0.5 1.0
c Krill,Cap
0.0 0.5 1.0 1.5
b Cap
-0.4-0.2 0.0 0.2 0.4
c Cod,Cap
-1.0-0.5 0.0 0.5 1.0Posterior values
c Cap,Cod
0.00.20.40.60.81.0
b Cod
0.0 0.5 1.0 1.5 2.0Posterior values
d Cal
-2 -1 0 1 2
d Krill
-1.0-0.5 0.0 0.5 1.0
d Cap
-0.4-0.2 0.0 0.2 0.4
d Cod
-1.0-0.5 0.0 0.5 1.0Posterior values
e Cal
-1.0-0.5 0.0 0.5 1.0
e Krill
-1.0-0.5 0.0 0.5 1.0
e Cap
-1.0-0.5 0.0 0.5 1.0
e Cod
-0.8-0.6-0.4-0.2 0.0Posterior values
f Cap
-0.6-0.4-0.2-0.0 0.2
f Cod
90% 80% 70% 60% 50% 40% 30% 20% 10%Degree of precaution [%]
0
20
40
60
80
100
Impa
cted
pop
ulai
ton
[% o
f unp
ertu
rbed
leve
l] 95% reduction in Krill biomass
0
5
10
15
Impa
ct d
urat
ion
[Yea
rs]
90% 80% 70% 60% 50% 40% 30% 20% 10%Degree of precaution [%]
0
20
40
60
80
100
Impa
cted
pop
ulat
ion
[% o
f unp
ertu
rbed
leve
l] 50% reduction in Krill biomass
0
5
10
15
Impa
ct d
urat
ion
[Yea
rs]
Cod
Capelin
Cod impact duration
Capelin impact duration
Cod$
Capelin$
Krill$ Calanus$spp.$
Temperature$
Fishing$
Young$Herring$
ICES CM 2015/B:21
