Cyanobacterial diversity in benthic mats of the McMurdo Dry Valley lakes, Antarctica
Perennially ice-covered, meromictic lakes in the McMurdo Dry Valleys, Antarctica, are useful models to study the relationship between cyanobacterial and environmental variables. They have rich benthic cyanobacterial mat accumulations and stable stratification of physical and chemical conditions. Here, we evaluated cyanobacteria from benthic mats from multiple depths in three geographically separated ice-covered lakes, Lakes Vanda, Hoare and Joyce, using 16S rRNA gene clone libraries. We identified 19 ribotypes, mostly Oscillatoriales and several Chroococcales, as well as potentially novel cyanobacterial ribotypes. The majority of ribotype diversity was shared between lakes, and only a weak relationship between ribotype community structure and environmental variables was evident. Multivariate analysis of all lake–depth combinations implied that photosynthetically active radiation, dissolved reactive phosphorus and conductivity were potentially important for shaping benthic communities in McMurdo Dry Valley lakes. Cyanobacterial-specific pigment signature analysis by high-performance liquid chromatography showed that the cyanobacterial communities responded to light conditions similarly, irrespective of community composition. The results imply a capability within a suite of cyanobacteria to colonise, adapt and grow across broad environmental ranges and geographic space, and such adaptability may provide a high degree of community resistance and resilience to future climate-driven environmental change in Antarctic terrestrial aquatic ecosystems.
KeywordsCyanobacteria 16S rRNA gene Microbial mat Pigment Diversity Lake Antarctica
We are grateful for the support from NASA’s Exobiology (NNX08AO19G) and Astrobiology (NNX09AE77A) programs; logistic support was provided by the US National Science Foundation Office of Polar Programs. We would like to acknowledge the interaction with the Taylor Valley Long-Term Ecological Research Programme (NSF Grant 115245), Stephen Emmons for assistance with the sample collection and three anonymous reviewers for insightful comments and suggestions.
Conflict of interest
The authors do not have any conflict of interest.
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