Aquatic herbivores as a regulating
factor of methane emission shallow
lakes
Paul L.E. Bodelier, Bas J.J. Dingemans, Liesbeth S. Bakker
Netherlands Institute of Ecology, Wageningen
Department of Microbial Ecology
Department of Aquatic Ecology
Netherlands Institute of Ecology
Nieuwersluis
Wageningen
WWW.NIOO.KNAW.NL
Netherlands Institute of Ecology
The Netherlands Institute of Ecology (NIOO-KNAW) conducts
marine, terrestrial and freshwater ecological research, with
the aim of elucidating how living organisms interact with
each other and with their surroundings. The Netherlands
Institute of Ecology (NIOO) is a top research institute of the
Royal Netherlands Academy of Arts and Sciences.
WWW.NIOO.KNAW.NL
Outline
Background
Methane, grazing and emergent macrophytes
Methane, grazing and submers macrophytes
Conclusions
Perspective
Background
Methane contributes 17% to total global warming
IPCC: Summary for policymakers (February 2007)
Background
Wetlands contribute 40-45% of total global methane
emission
Science:327:322-324
Bloom et al 2010: Science:327:322
Background
Wetlands plants affect methane cycling processes and facilitate
the emission of methane from wetlands.
methane
Floodwater
Anoxic soil
Carbon
Methane producing
archaea
methane
Air (oxygen)
Background
Wetland birds affect plants………..and ……
© Mark Kuiper
Background
Wetlands birds consume above ground parts of wetland
plants
Background
Wetlands birds consume above ground as well as below
ground parts of wetland plants
winter
autumn
spring
summer
Questions
Does grazing by aquatic herbivores affect methane
emission from wetlands?
Is the effect different for emergent vs. submerse
macrophytes?
Approach
Bird exclosures in lake “ Waterleidingplas” , Loenderveen,
since 2006.
Approach
Approach
Approach
12V
1
2
2
3
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Approach
Results
Figure 1
100
Grazed
Ungrazed
Stems.m-2
80
60
40
20
0
C
E
May
C
E
June
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
C
E
July
C
E
Sept
Results
Figure 1
100
Grazed
Ungrazed
Stems.m-2
80
60
40
20
0
C
E
May
C
E
June
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
C
E
July
C
E
Sept
Results
Individual shoots
Diffusive CH4 flux (mg stem-1 day-1)
40
Ungrazed
Grazed
30
20
10
0
Jun
Jul
Aug
Sep
Jun-Sep
RMA: p<0.011 (excluding sept.)
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Results
Area based (large chambers)
Diffusive CH4 flux (mg m-2 day-1)
1000
800
No Plants
Ungrazed
Grazed
600
400
200
0
Jul
Aug
Sep
RMA: p<0.017
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Jul-Sep
Results
Individual stem (large chambers)
Diffusive CH4 flux (mg stem-1 day-1)
8
Ungrazed
Grazed
6
4
2
0
Jul
Aug
Sep
RMA: p<0.058
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Jul-Sep
Results
Process level: methane oxidation
July
Aug
Sept
-3
-1
Methane oxidation (nmol.cm .h )
200
150
100
50
0
Grazed
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Ungrazed
Results
July
Aug
Sept
-3
-1
Methane production (nmol.cm .h )
50
Process level: methane production
40
30
20
10
0
Grazed
Dingemans, Bakker, Bodelier, 2011. Ecology 92:116692:1166-1173.
Ungrazed
Conclusion
Grazing of reeds by aquatic herbivores leads to 4-5
times higher methane emission probably due to physical
effects on gas diffusion through grazed stems.
General conclusion
Aquatic herbivores can modulate methane emission from
wetlands with contrasting effects when grazing on emergent
and submerse macrophytes.
Increased presence of waterfowl in wetlands (especially
Northern wetlands) due to climate change may lead to
changes in methane emission.
Perspective
Perspective
Climate change?
Acknowledgements
Financial support
KNAW Vernieuwingsfonds
Schure-Beijerinck-Popping fonds
Strategic funds NIOO
NIOO-KNAW, ME
Marion Meima-Franke, Anne Steenbergh, Anne Daebeler, Roos Keijzer
NIOO-KNAW, PAI
Koos Swart, Thijs de Boer, Peter de Vries
Marcel Klaassen, Bart Nolet, Bert Hidding, Abel Gyimesi, Casper van
Leeuwen, Naomi Huig