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1. A New Thermal Categorization of Ice‐Covered Lakes

   https://doi.org/10.1029/2020GL091374  

   Yang, Bernard; Wells, Mathew G.; McMeans, Bailey C.; Dugan, Hilary A.; Rusak, James A.; Weyhenmeyer, Gesa A.; Brentrup, Jennifer A.; Hrycik, Allison R.; Laas, Alo; Pilla, Rachel M.; et al (February 2021, Geophysical Research Letters)

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2. Inorganic carbon fixation in ice-covered lakes of the McMurdo Dry Valleys

   https://doi.org/10.1017/S0954102019000075  

   Vick-Majors, Trista J.; Priscu, John C. (June 2019, Antarctic Science)

   Abstract Inorganic carbon fixation, usually mediated by photosynthetic microorganisms, is considered to form the base of the food chain in aquatic ecosystems. In high-latitude lakes, lack of sunlight owing to seasonal solar radiation limits the activity of photosynthetic plankton during the polar winter, causing respiration-driven demand for carbon to exceed supply. Here, we show that inorganic carbon fixation in the dark, driven by organisms that gain energy from chemical reactions rather than sunlight (chemolithoautotrophs), provides a significant influx of fixed carbon to two permanently ice-covered lakes (Fryxell and East Bonney). Fryxell, which has higher biomass per unit volume of water, had higher rates of inorganic dark carbon fixation by chemolithoautotrophs than East Bonney (trophogenic zone average 1.0 µg C l −1 d −1 vs 0.08 µg C l −1 d −1 , respectively). This contribution from dark carbon fixation was partly due to the activity of ammonia oxidizers, which are present in both lakes. Despite the potential importance of new carbon input by chemolithoautotrophic activity, both lakes remain net heterotrophic, with respiratory demand for carbon exceeding supply. Dark carbon fixation increased the ratio of new carbon supply to respiratory demand from 0.16 to 0.47 in Fryxell, and from 0.14 to 0.22 in East Bonney. 

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3. In a PICL: The sedimentary deposits and facies of perennially ice-covered lakes

   https://doi.org/10.1111/sed.12522  

   Rivera-Hernandez, Frances; Sumner, Dawn Y.; Mackey, Tyler J.; Hawes, Ian; Andersen, Dale T.; Girardclos, Stéphanie (April 2019, Sedimentology)
4. Morphology and Distribution of Bubble‐Supported Microbial Mats From Ice‐Covered Antarctic Lakes

   https://doi.org/10.1029/2024JG008516  

   Juarez_Rivera, M; Mackey, T J; Hawes, I; Sumner, D Y (March 2025, Journal of Geophysical Research: Biogeosciences)

   Abstract Gas bubbles directly influence the macromorphology of benthic microbial mats resulting in preservable biosedimentary structures. This study characterizes the morphology and distribution of microbial mats growing in gas‐supersaturated, perennially ice‐covered lakes Fryxell, Joyce, and Hoare of the McMurdo Dry Valleys of Antarctica. Photosynthetic benthic mats within the gas‐supersaturated zone trap oxygen‐rich bubbles and become buoyant, tearing off the bottom as “liftoff mats.” These liftoff mats form a succession of morphologies starting with bubble‐induced deformation of flat mats into tent, ridge, and finger liftoff mat. With progressive deformation, mats tear, forming sheet liftoff, while multiple cycles of deformation and tearing transform sheet into strip liftoff. Some mats detach from the substrate and float to the underside of the ice. The depth range of the liftoff zone has varied over time at each lake. Downslope expansion of bubble formation brings previously bubble‐free, deep‐water pinnacle mats into the liftoff zone. When the liftoff zone shallows, liftoff mats at the deeper end deflate and can become scaffolding for additional mat growth. The superposition and relative orientation of liftoff and pinnacle mats can be used to track the maximum depth of the liftoff zone and changes in gas saturation state in these lakes through time. Our results demonstrate that gas bubbles, even when they are transitory, can exert a significant impact on the morphology of microbial mats at larger scales. This provides a way to identify similar structures and gas supersaturated environments in the biosedimentary record. 

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5. Antarctic lake viromes reveal potential virus associated influences on nutrient cycling in ice-covered lakes

   https://doi.org/10.3389/fmicb.2024.1422941  

   Robinson, David; Morgan-Kiss, Rachael M; Wang, Zhong; Takacs-Vesbach, Cristina (September 2024, Frontiers in Microbiology)

   The McMurdo Dry Valleys (MDVs) of Antarctica are a mosaic of extreme habitats which are dominated by microbial life. The MDVs include glacial melt holes, streams, lakes, and soils, which are interconnected through the transfer of energy and flux of inorganic and organic material via wind and hydrology. For the first time, we provide new data on the viral community structure and function in the MDVs through metagenomics of the planktonic and benthic mat communities of Lakes Bonney and Fryxell. Viral taxonomic diversity was compared across lakes and ecological function was investigated by characterizing auxiliary metabolic genes (AMGs) and predicting viral hosts. Our data suggest that viral communities differed between the lakes and among sites: these differences were connected to microbial host communities. AMGs were associated with the potential augmentation of multiple biogeochemical processes in host, most notably with phosphorus acquisition, organic nitrogen acquisition, sulfur oxidation, and photosynthesis. Viral genome abundances containing AMGs differed between the lakes and microbial mats, indicating site specialization. Using procrustes analysis, we also identified significant coupling between viral and bacterial communities (p = 0.001). Finally, host predictions indicate viral host preference among the assembled viromes. Collectively, our data show that: (i) viruses are uniquely distributed through the McMurdo Dry Valley lakes, (ii) their AMGs can contribute to overcoming host nutrient limitation and, (iii) viral and bacterial MDV communities are tightly coupled. 

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