climate, zooplankton and pelagic fish growth in the central baltic sea christian möllmann © georgs...
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Climate, zooplankton and pelagic fish growth in the Central Baltic Sea
Christian Möllmann ©Georgs Kornilovs ®
Marina Fetter ®Friedrich W. Köster ©
© Danish Institute for Fisheries Research, Charlottenlund® Latvian Fisheries Research Institute, Riga
Ministry of Food, Agriculture and FisheriesDanish Institute for Fisheries Research
Stock development
herring
sprat
stoc
k si
ze (
num
ber
s)
0
2e+10
4e+10
6e+10
8e+10
wei
ght-
at-ag
e (k
g)
0.02
0.03
0.04
0.05
0.06
0.07
0.08stock size
weight- at- age
1980 1985 1990 1995 2000
0
1e+11
2e+11
3e+11
4e+11
5e+11
0.008
0.010
0.012
0.014
0.016
0.018
Condition*
herring
cond
itio
n (g
)
40
45
50
sprat
1980 1985 1990 1995 2000
cond
itio
n (g
)
25
30
35
*log-log regression;weight at mean length;spring
Aim(s)
• show effect of climate on Baltic hydrography• demonstrate effect of hydrography on dominating copepod species• evaluate if trends in copepods affect feeding of herring and sprat• relate trends in feeding to condition• explain growth changes ?
Time-series
• quarterly, 1977-2003• climate index (BSI)• hydrography (T, S & O2)• mesozooplankton abundance• herring & sprat stomach contents• herring & sprat length+weight• Gdansk Deep & Gotland Basin
Climate
1980 1985 1990 1995 2000
BSI
-6
-4
-2
0
2
4
6
8
BSI
Plot 2 Zero
Baltic Sea Index (BSI)
Climate & hydrography
BSI-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
deg
C
0.4
0.5
0.6
0.7
0.8
0.9
Temperature(O-50m)
r=0.60
BSI-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
psu
0.90
0.92
0.94
0.96
0.98
1.00
1.02
1.04
Salinity(50-100m)
r=0.62
Copepod community change
0%
25%
50%
75%
100%
Acartia
TemoraPseudocalanus
Acartia/Temora & temperature
1980 1985 1990 1995 2000stan
dar
diz
ed a
bun
dan
ce (
n*m
-2)
& t
empe
ratu
re 0
-50m
(deg
C)
-2
-1
0
1
2
3
Acartia
Temora
temperature
r = 0.69 (Acartia) – r = 0.79 (Temora)
Process behind Acartia/temperature
Eg
g p
rod
uct
ion
[eg
gs
fem
-1 d
-1]
Tem
per
atu
re
Hatch
ing
%
0
10
20
30
40
0 4 8 12 16 20 24 28 32 36 40
4 °C10 °C
Resting eggs vs. in-situ egg production
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9
0
20
40
60
80
100egg productiontemperaturehatching
month
Dutz et al., 2004
weeks
1980 1985 1990 1995 2000stan
dar
diz
ed a
bun
dan
ce (
n*m
-2)
& s
alin
ity
50-100m
(ps
u)& o
xyg
en (
ml*
l-1)
-2
-1
0
1
2
3Pseudocalanus
salinity
oxygen
Pseudocalanus & salinity(& oyxgen)
r = 0.46 (with 1993) – r = 0.69 (without 1993)
Process behind Pseudocalanus/salinity
Color scale – salinity [PSU]
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0- 9 0
- 8 0
- 7 0
- 6 0
- 5 0
- 4 0
- 3 0
- 2 0
- 1 0
67891 01 11 21 31 41 51 61 71 81 9
Schmidt et al., 2003
May 2002 (stagnation) April 2003 (post-inflow)
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0- 9 0
- 8 0
- 7 0
- 6 0
- 5 0
- 4 0
- 3 0
- 2 0
- 1 0
67891 01 11 21 31 41 51 61 71 81 9
Color scale – salinity [PSU]Black line – oxygen content [ml*l-1] Schmidt et al., 2003
Process behind Pseudocalanus/salinity
May 2002 (stagnation) April 2003 (post-inflow)
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0- 9 0
- 8 0
- 7 0
- 6 0
- 5 0
- 4 0
- 3 0
- 2 0
- 1 0
67891 01 11 21 31 41 51 61 71 81 9
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0
Color scale – salinity [PSU]Black line – oxygen content [ml*l-1]Red dots – individual egg-carrying females Schmidt et al., 2003
Process behind Pseudocalanus/salinity
May 2002 (stagnation) April 2003 (post-inflow)
Herring feeding
summer
1980 1985 1990 1995 2000
wet
wei
ght
(g)
0.00
0.04
0.08
0.12
0.16
0.20
other copepodsAcartiaTemora
Pseudocalanus
spring
wet
wei
ght
(g)
0.00
0.02
0.04
0.06
0.08
0.10
Condition - causes
log Pseudocalanus4.2 4.4 4.6 4.8 5.0
log
cond
itio
n
1.60
1.62
1.64
1.66
1.68
1.70
1.72
Herring - spring
r= 0.60
log sprat10.4 10.6 10.8 11.0 11.2 11.4 11.6 11.8
r = 0.71
spring
wet
wei
ght
(g)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
mean stomach contentcondition
summer
1980 1985 1990 1995 2000
wet
wei
ght
(g)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
Sprat feeding
other copepodsAcartiaTemoraPseudocalanus
cladocerans
77- 90 91- 0320
25
30
spring
summer
condition
77- 90 91- 03
500.0x103
1.0x106
1.5x106
2.0x106
2.5x106
plankton
77- 90 91- 03
100x109
200x109
300x109
sprat stock
Condition - causes
Sprat – spring & summer
Summary
• strong link between climate and hydrography• salinity and temperature changes determine copepod community• decrease in Pseudocalanus affected herring growth• no ”plankton effect” on sprat growth• strong competition due to large sprat stock• no direct effect of temperature & salinity