The pivotal role of mesograzers in modulating the impact ... · Indirect effects of warming on...
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The pivotal role of mesograzers in modulating the impact of ocean warming on Fucus The actors: 1. Structural, prennial macroalgae: Fucus serratus and Fucus vesiculosus 2. Shading filamentous epiphytes 3. Mesograzers: Idotea balthica, Gammarus spp. 4. Fishes: stickleback... 5. Bioc students Hypotheses: Fv and Fs are differently impacted by epiphytes Fish impair Fucus by suppressing mesograzer control of epiphytes OW impact on Fucus will be mitigated by mesograzers OW impact on Fucus enhanced by fish Background: OW favors filamentous algae which may be controlled by mesograzers. Mesograzers are favoured by moderate and inhibited by strong OW Fish reduce the abundance (and size?) of mesograzers Fucus are negatively impacted by epiphytes (and OW) Benthocosm Experiment 2017 1
Transcript of The pivotal role of mesograzers in modulating the impact ... · Indirect effects of warming on...
The pivotal role of mesograzers in modulating the impact of ocean warming on Fucus
The actors: 1. Structural, prennial macroalgae: Fucus serratus and Fucus vesiculosus 2. Shading filamentous epiphytes 3. Mesograzers: Idotea balthica, Gammarus spp. 4. Fishes: stickleback... 5. Bioc students
Hypotheses: Fv and Fs are differently impacted by epiphytes Fish impair Fucus by suppressing mesograzer control of epiphytes OW impact on Fucus will be mitigated by mesograzers OW impact on Fucus enhanced by fish
Background: OW favors filamentous algae which may be controlled by mesograzers. Mesograzers are favoured by moderate and inhibited by strong OW Fish reduce the abundance (and size?) of mesograzers Fucus are negatively impacted by epiphytes (and OW)
Benthocosm Experiment 2017 1
The infrastructure: Kiel Outdoor Benthocosms
Bioacid II: Seasonal response patterns
Benthocosm Experiment 2017 2
Indirect effects of
warming on epiphytes and F. vesiculosus were
mediated by grazers
ambient temperaturehigh temperature
0 800 1600
Grazer ab
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 6000 1200018000
Grazer bm [g AFDW]
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 800 1600
Grazer ab
0
5
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25
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Ma
cro
ep
iph
yte
bm
[g
DW
]
0 6000 1200018000
Grazer bm [g AFDW]
0
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Ma
cro
ep
iph
yte
bm
[g
DW
]
0 400 800 12001600
Grazer ab
0
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Fu
cu
s b
m [g
FW
]
0 6000 1200018000
Grazer bm [mg AFDW]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0x100
4x107
8x107
Microepiphyte bm [pgC]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0x100
4x100
8x100
Macroepiphyte bm [g DW]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
r=-0.72 p=.01
Grazer ab
Mic
roep
iph
yte
bm
[p
gC]
0 800 1600
Grazer ab
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 6000 1200018000
Grazer bm [g AFDW]
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 800 1600
Grazer ab
0
5
10
15
20
25
30
Ma
cro
ep
iph
yte
bm
[g
DW
]
0 6000 1200018000
Grazer bm [g AFDW]
0
5
10
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20
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30
Ma
cro
ep
iph
yte
bm
[g
DW
]
0 400 800 12001600
Grazer ab
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Fu
cu
s b
m [g
FW
]
0 6000 1200018000
Grazer bm [mg AFDW]
0
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40
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100
Fu
cu
s b
m [g
FW
]
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4x107
8x107
Microepiphyte bm [pgC]
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20
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Fu
cu
s b
m [g
FW
]
0x100
4x100
8x100
Macroepiphyte bm [g DW]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
r=0.60 p<.05
Grazer ab
Fucu
s b
m [
gFW
]
0 800 1600
Grazer ab
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 6000 1200018000
Grazer bm [g AFDW]
0x100
107
2x107
3x107
4x107
Mic
roe
pip
hyte
bm
[p
gC
]
0 800 1600
Grazer ab
0
5
10
15
20
25
30
Ma
cro
ep
iph
yte
bm
[g
DW
]
0 6000 1200018000
Grazer bm [g AFDW]
0
5
10
15
20
25
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Ma
cro
ep
iph
yte
bm
[g
DW
]
0 400 800 12001600
Grazer ab
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0 6000 1200018000
Grazer bm [mg AFDW]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0x100
4x107
8x107
Microepiphyte bm [pgC]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0x100
4x100
8x100
Macroepiphyte bm [g DW]
0
20
40
60
80
100
Fu
cu
s b
m [g
FW
]
0x100
2x107
4x107
Microepiphyte bm [pgC]
0
20
40
60
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100
Fu
cu
s b
m [g
FW
]Fu
cus
bm
[gF
W]
Microepiphyte bm [pgC]
r=-0.69 p<.05
F. Werner B. Matthiessen GEOMAR 2015
Controlled by warming, grazers may reduce epiphytes and thereby favour Fucus Benthocosm Experiment 2017 3
OW
4
Example: Warming – Grazing – Epibiosis - Fucus
Ecosystem services (structure, C & N binding, O2…) Benthocosm Experiment 2017
Performance items:
D = defense production
G = growth
P = photosynthesis
R = reproduction
reduction
enhancement
Summer
P
R
Fucus
G
Grazing rates
Epiphytism Warming
Acidifi- cation
Grazer abundance
Nutrient enrich- ment
Epibiotic biofilms
D
modulation
Benthocosm Experiment 2017 5
Fish
Burning ember for the fate of a Fucus community
F u c u s v e s i c u l o s u s
Gro
wth
Rep
ro
Def
ense
Spring Winter Summer Autumn
Very high risk
High risk
Low risk
Beneficial effect
Burning ember for the fate of a Fucus community
E p i p h y t e s
Mic
ro
Mac
ro
Spring Winter Summer Autumn
M e s o g r a z e r s A
mp
hi
Iso
Very high risk
High risk
Low risk
Beneficial effect
Burning ember for the fate of a Fucus community
F i l t e r f e e d e r s
Bal
anu
s
Myt
ilus
Spring Winter Summer Autumn
P r e d a t o r s
Ast
eria
s
Very high risk
High risk
Low risk
Beneficial effect
Tambient
T ∆5°C
Set-up
Benthocosm Experiment 2017 9
The beneficial (cleaning) or detrimental (consumption) role of gammarid mesograzers under present and future temperature conditions on two important Fucus species
x
x
Tambient
T ∆5°C
Tasks Continuous logging of pH, salinity, O2 A
pri
l Set-up Fish (y/n), mesograzers (y/n), F. vesiculosus & serratus
Fucus assessment
Fucus WW, C/N, epibiosis, performance (O2 prod)
Ecosystem assessment
24h monitoring (O2, pH, DIC, TA, plankt. CHl a)
May
Structural assessment
Fucus WW and length growth, C/N, epibiosis, performance (O2 prod), abundance & size mesograzers
Functional assessment
24h monitoring (O2, pH, DIC, TA, nutrients, plankt. CHl a), Fucus performance (O2 prod), feeding rates of mesograzers
Jun
e
Structural assessment
Fucus WW and length growth, C/N, epibiosis, performance (O2 prod), abundance & size mesograzers
Functional assessment
24h monitoring (O2, pH, DIC, TA, nutrients, plankt. CHl a), Fucus performance (O2 prod), feeding rates of mesograzers ...
July
Structural assessment
Fucus WW and length growth, C/N, epibiosis, performance (O2 prod), abundance & size mesograzers
Functional assessment
24h monitoring (O2, pH, DIC, TA, nutrients, plankt. CHl a), Fucus performance (O2 prod), feeding rates of mesograzers ...
Trophic structure
stable isotopes of all components
Set-up in mid-March
Benthocosm Experiment 2017 10
x
x
Benthocosm Experiment 2017 11
Possible project topics
(to be done alone, in student pairs, or in collaboration with a scientist)
• Effect of OW on population growth of gamarids
• Effect of temperature on consumption rates of gammarids
• Effect of OW on palatability of Fucus vesiculosus and Fucus serratus
• Do the two Fucus species differ in their responses to OW (reg.
photosynthesis, growth, palatability)?
• Effect of OW on filamentous epiphytes on Fucus
• Control of epiphytism by mesograzers und ambient and warmed conditions
• Changes of ecosystem functions in repsonse to OW and/or grazing
• ....
Benthocosm Experiment 2017 12
ANOVA REGRESSION (regular)
REGRESSION (random)
+0
+1
+2
+3
´4
+5
∆T°
The tiny engineers of Global Change W
ar
min
g
+1°
+2°
+3°
+4°
+5°
today
Moderate grazing -> epiphytes Fucus
Intense grazing -> Fucus
No grazing -> explosion of epiphytes Fucus
All year round Fucus contributes to a healthy environment provides shelter for juvenile fish habitat for numerous species supplies oxygen binds CO2 mitigates ocean acidification
X
X
Small swimming crustaceans: amphipods, isopods
What you see: tanks with and without grazers and with warming between 0 and 5°C (from light to dark shades)
N (left)
S (right)
Warming -> Grazer response -> Macroalgal response -> Ecosystem response
Expectation: with increasing warming the ecologically important macroalga Fucus will first suffer from excessive grazing, then from excessive overgrowth and may finally disappear
Responsible: Prof. Dr. Martin Wahl (GEOMAR), more infos:
