Methanotrophic activity and diversity in different <i>Sphagnum magellanicum</i> dominated habitats in the southernmost peat bogs of Patagonia
<i>Sphagnum</i> peatlands are important ecosystems in the methane cycle. Methanotrophs living inside the dead hyaline cells or on the <i>Sphagnum</i> mosses are able to act as a methane filter and thereby reduce methane emissions. We investigated in situ methane concentration...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2012-01-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/9/47/2012/bg-9-47-2012.pdf |
| Summary: | <i>Sphagnum</i> peatlands are important ecosystems in the methane cycle. Methanotrophs
living inside the dead hyaline cells or on the <i>Sphagnum</i> mosses are able to act as a
methane filter and thereby reduce methane emissions. We investigated in situ methane
concentrations and the corresponding activity and diversity of methanotrophs
in different <i>Sphagnum</i> dominated bog microhabitats. In contrast to the Northern
Hemisphere peat ecosystems the temperate South American peat bogs are
dominated by one moss species; <i>Sphagnum magellanicum</i>. This permitted a species-independent
comparison of the different bog microhabitats. Potential methane oxidizing
activity was found in all <i>Sphagnum</i> mosses sampled and a positive correlation was
found between activity and in situ methane concentrations. Substantial methane
oxidation activity (23 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>−1</sup>) was found in
pool mosses and could be correlated with higher in situ methane concentrations
(>35 μmol CH<sub>4</sub> l<sup>−1</sup> pore water). Little methanotrophic activity
(<0.5 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>−1</sup>) was observed in living
<i>Sphagnum</i> mosses from lawns and hummocks. Methane oxidation activity was relatively
high (>4 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>−1</sup>) in <i>Sphagnum</i> litter at depths
around the water levels and rich in methane. The total bacterial community
was studied using 16S rRNA gene sequencing and the methanotrophic
communities were studied using a <i>pmo</i>A microarray and a complementary <i>pmo</i>A clone
library. The methanotrophic diversity was similar in the different habitats
of this study and comparable to the methanotrophic diversity found in peat
mosses from the Northern Hemisphere. The <i>pmo</i>A microarray data indicated that
both alpha- and gammaproteobacterial methanotrophs were present in all
<i>Sphagnum</i> mosses, even in those mosses with a low initial methane oxidation activity.
Prolonged incubation of <i>Sphagnum</i> mosses from lawn and hummock with methane revealed
that the methanotrophic community present was viable and showed an increased
activity within 15 days. The high abundance of methanotrophic <i>Methylocystis</i> species in the
most active mosses suggests that these might be responsible for the bulk of
methane oxidation. |
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| ISSN: | 1726-4170 1726-4189 |