CH4 Flux from Sub-arctic Mire Lakes: A Look at Relationships Between Microbial Communities and Submerged Aquatic Vegetation
Abstract
High latitude ecosystems are warming at a rapid rate, increasing permafrost thaw and thereby providing fresh sources of organic carbon ( C) to post-glacial lakes. These lakes are a significant source of methane (CH4) emissions into the atmosphere, however little is known about the reason for variations in these emissions within and between lakes. Stordalen Mire is a 25-ha hydrologically connected system of lakes and wetlands in the discontinuous permafrost zone in northern Sweden. Strong correlations between methanotroph lineage A NME-2d within lake sediments using 16S rRNA sequence data and sediment CH4 concentration measurements. Similar trends have also been observed with methanogen lineage M. Stordalenmirensis and sediment δ13C H4 measurements as well as relationships between these two microbial lineages. However, previous work has shown no strong relationships between carbon sediment geochemistry and submerged aquatic macrophyte (SAM) vegetation. We have shown strong microbial-microbial relationships and their correlations with CH4 and now ask what microbial-vegetation interactions between SAM vegetation and their associated microbial community exist in these lakes and how does that relate to measured CH4?
The effect of plant species on the CH4 flux from microbial community was investigated by constructing plant-sediment microcosms and incubating them with CH4 at a n initial concentration of 1% v/v for 32 hours at 25°C . Incubations were each performed with two SAM species (Potamogeton and chara) collected from one of the Abisko lakes (Inre Harrsjön). Furthermore, incubations were performed with sediment from the depths of 0-1 cm, 4-5 cm, and 8-9 cm depth s of cores that were taken from both high and low CH4 emitting areas of the Inre Harrsjön lake to assess sediment geochemistry and microbial community composition. After the incubation period, these geochemical and microbial community analysis were performed on the same samples t o identify changes that may have occurred in microcosm based on th e different treatment parameters . Preliminary results show variation in CH4 uptake between the different parts of the incubated plant material as well as between species of plant. These results provide early evidence of the impact of microbial-plant interactions in C cycling in sub-arctic lake sediment systems.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B41J2454M
- Keywords:
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- 0412 Biogeochemical kinetics and reaction modeling;
- BIOGEOSCIENCES;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCES