Lake sediment microbial communities vary across ecosystems and are often differentiated across pH. Additionally, these pH‐mediated differences in community composition are often correlated with changes in sediment functioning, such as methane and carbon dioxide production. However, few studies have experimentally tested pH effects on community assembly or considered how microbial community composition influences ecosystem function independent of differences in the environment. We used common garden experiments to test hypotheses about how pH influences microbial community assembly and function in lake sediments. Using inoculum from three acidic lakes and three near‐neutral lakes, we found that both pH environment and inoculum source significantly influenced sediment microbial community assembly. However, inoculum source had a larger effect size for both the sediment methanogen and nonmethanogen communities, indicating important roles of dispersal and drift. Additionally, inoculum source, but not pH environment, significantly influenced sediment methane and carbon dioxide production. This research is one of the first to experimentally test the influence of pH on sediment microbial community composition, and in doing so, we show the community composition significantly influences sediment function independent of pH. Understanding how lake sediment microbial communities are influenced by environment is the first step toward mechanistically linking changes in community composition to ecosystem function, and we provide critical evidence for how changes in microbial community assembly with environmental change will likely alter carbon cycling in lake sediments.
Little is known about how the geological history of an environment shapes its physical and chemical properties and how these, in turn, influence the assembly of communities. Evening primrose (EP), a moderately acidic hot spring (pH 5.6, 77.4°C) in Yellowstone National Park (YNP), has undergone dramatic physicochemical change linked to seismic activity. Here, we show that this legacy of geologic change led to the development of an unusual sulphur‐rich, anoxic chemical environment that supports a unique archaeal‐dominated and anaerobic microbial community. Metagenomic sequencing and informatics analyses reveal that >96% of this community is supported by dissimilatory reduction or disproportionation of inorganic sulphur compounds, including a novel, deeply diverging sulphate‐reducing thaumarchaeote. When compared to other YNP metagenomes, the inferred functions of EP populations were like those from sulphur‐rich acidic springs, suggesting that sulphur may overprint the predominant influence of pH on the composition of hydrothermal communities. Together, these observations indicate that the dynamic geological history of EP underpins its unique geochemistry and biodiversity, emphasizing the need to consider the legacy of geologic change when describing processes that shape the assembly of communities.
more » « less- Award ID(s):
- 1820658
- NSF-PAR ID:
- 10455446
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Environmental Microbiology
- Volume:
- 21
- Issue:
- 11
- ISSN:
- 1462-2912
- Page Range / eLocation ID:
- p. 4180-4195
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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