Microbial processes of the carbon and sulfur cycles in an ice‐covered, iron‐rich meromictic lake <scp>S</scp>vetloe (<scp>A</scp>rkhangelsk region, <scp>R</scp>ussia)

• Published in: Environmental Microbiology
• Main Authors: Savvichev, Alexander S., Kokryatskaya, Natalia M., Zabelina, Svetlana A., Rusanov, Igor I., Zakharova, Elena E., Veslopolova, Elena F., Lunina, Olga N., Patutina, Ekaterina O., Bumazhkin, Boris K., Gruzdev, Denis S., Sigalevich, Pavel A., Pimenov, Nikolay V., Kuznetsov, Boris B., Gorlenko, Vladimir M.
• Other Authors: Russian Foundation for Basic Research
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Ecology, Evolution, Behavior and Systematics; Microbiology; White Sea
• Online Access: http://dx.doi.org/10.1111/1462-2920.13591; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1462-2920.13591; http://onlinelibrary.wiley.com/wol1/doi/10.1111/1462-2920.13591/fullpdf

Summary Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ∼0.5 m, and the ice‐covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23–24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L −1 day −1 ) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L −1 day −1 ) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L −1 day −1 ) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH 4 L −1 day −1 at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin‐containing Synechococcus ‐related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone.