Aquatic herbivores as a regulating factor of methane emission ...

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Aquatic herbivores as a regulating factor of methane emission ...

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

Bloom et al 2010: Science:327:322-324

324


Background

Wetlands plants affect methane cycling processes and facilitate

the emission of methane from wetlands.

methane

Air (oxygen)

Floodwater

Anoxic soil

Carbon

Methane producing

archaea

methane


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

spring

autumn

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

1

12V

2

2

3

Dingemans, Bakker, Bodelier, 2011. Ecology 92:1166-1173.

1173.


Approach


Results

Figure 1

100

Grazed

Ungrazed

80

Stems.m -2

60

40

20

0

C E C E C E C E

May June July Sept

Dingemans, Bakker, Bodelier, 2011. Ecology 92:1166-1173.

1173.


Results

Figure 1

100

Grazed

Ungrazed

80

Stems.m -2

60

40

20

0

C E C E C E C E

May June July Sept

Dingemans, Bakker, Bodelier, 2011. Ecology 92:1166-1173.

1173.


Results

40

Individual shoots

Diffusive CH -1 day -1 4

flux (mg stem )

30

20

10

Ungrazed

Grazed

0

Jun Jul Aug Sep Jun-Sep

RMA: p


Results

1000

Area based (large chambers)

Diffusive CH -2 day -1 4

flux (mg m )

800

600

400

200

No Plants

Ungrazed

Grazed

0

Jul Aug Sep Jul-Sep

RMA: p


Results

8

Individual stem (large chambers)

Diffusive CH -1 day -1 4

flux (mg stem )

6

4

2

Ungrazed

Grazed

0

Jul Aug Sep Jul-Sep

RMA: p


Results

200

Process level: methane oxidation

Methane oxidation (nmol.cm

-3 .h -1 )

150

100

50

July

Aug

Sept

0

Grazed

Ungrazed

Dingemans, Bakker, Bodelier, 2011. Ecology 92:1166-1173.

1173.


Results

50

Process level: methane production

Methane production (nmol.cm

-3 .h -1 )

40

30

20

10

July

Aug

Sept

0

Grazed

Ungrazed

Dingemans, Bakker, Bodelier, 2011. Ecology 92:1166-1173.

1173.


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

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