02348nas a2200217 4500008004100000245023200041210006900273260001200342300001200354490000700366520154300373653001501916653002001931653000801951653002001959653001401979653002101993100002102014700002402035856007102059 2025 eng d00aChemical signatures of microbial life in an ecological end-member: Shifting hydroclimate and sediment fluxes influence DOM biogeochemistry in Lake Fryxell, a permanently ice-covered lake in the McMurdo Dry Valleys of Antarctica0 aChemical signatures of microbial life in an ecological endmember c04/2025 a24786780 v573 a

The ice-covered lakes in the McMurdo Dry Valleys (MDV) of Antarctica provide end-member ecosystems for understanding the production of dissolved organic matter (DOM) in aquatic ecosystems in the absence of vegetation on the landscape and under resource and nutrient constraints. Given these constraints, DOM in MDV lakes is derived solely from microbial phototrophs and heterotrophic bacteria, contrasting with the dominant terrestrial sources in temperate regions. Previous research developed fluorometric approaches for characterizing DOM, including in MDV lakes. In this study we leveraged these approaches along with contemporary molecular-based techniques to elucidate changes in DOM composition across the depth profile for Lake Fryxell in the MDV. The results showed that the presence of organic molecules containing sulfur increased at depth where anoxic conditions prevailed. To evaluate the influences of climate-induced rising lake levels and multiple flood events in the MDV, we compared recent and historical samples. The results indicated a remarkable consistency in source-related fluorescence metrics over time, whereas a twofold decrease in sulfur content of the fulvic acid fraction was observed in samples from above and below the oxycline. Biogeochemical processes associated with the influx of iron oxide–rich sediments during flood events may have contributed to this change, and similar processes may stimulate biogeochemical cycling and remineralization in temperate lakes during seasonal transitions.

10aAntarctica10abiogeochemistry10aDOM10alake metabolism10alimnology10anutrient cycling1 aRue, Garrett, P.1 aMcKnight, Diane, M. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2025.247867803241nas a2200505 4500008004100000022001400041245010400055210006900159260001200228300001800240490000700258520177600265653001502041653001302056653001402069653001302083653001902096100002202115700001802137700001602155700002402171700002302195700002302218700001502241700002202256700001802278700002202296700002302318700002402341700002202365700001902387700002302406700001302429700002302442700002102465700002702486700002402513700002302537700001402560700002602574700002002600700003102620700001502651856006902666 2025 eng d a0043-139700aOne-hundred fundamental, open questions to integrate methodological approaches in lake ice research0 aOnehundred fundamental open questions to integrate methodologica c05/2025 ae2024WR0390420 v613 a

The rate of technological innovation within aquatic sciences outpaces the collective ability of individual scientists within the field to make appropriate use of those technologies. The process of in situ lake sampling remains the primary choice to comprehensively understand an aquatic ecosystem at local scales; however, the impact of climate change on lakes necessitates the rapid advancement of understanding and the incorporation of lakes on both landscape and global scales. Three fields driving innovation within winter limnology that we address here are autonomous real-time in situ monitoring, remote sensing, and modeling. The recent progress in low-power in situ sensing and data telemetry allows continuous tracing of under-ice processes in selected lakes as well as the development of global lake observational networks. Remote sensing offers consistent monitoring of numerous systems, allowing limnologists to ask certain questions across large scales. Models are advancing and historically come in different types (process-based or statistical data-driven), with the recent technological advancements and integration of machine learning and hybrid process-based/statistical models. Lake ice modeling enhances our understanding of lake dynamics and allows for projections under future climate warming scenarios. To encourage the merging of technological innovation within limnological research of the less-studied winter period, we have accumulated both essential details on the history and uses of contemporary sampling, remote sensing, and modeling techniques. We crafted 100 questions in the field of winter limnology that aim to facilitate the cross-pollination of intensive and extensive modes of study to broaden knowledge of the winter period.

10acryosphere10alake ice10alimnology10amodeling10aremote sensing1 aCulpepper, Joshua1 aSharma, Sapna1 aGunn, Grant1 aMagee, Madeline, R.1 aMeyer, Michael, F.1 aAnderson, Eric, J.1 aArp, Chris1 aCooley, Sarah, W.1 aDolan, Wayana1 aDugan, Hilary, A.1 aDuguay, Claude, R.1 aJones, Benjamin, M.1 aKirillin, Georgiy1 aLadwig, Robert1 aLeppäranta, Matti1 aLong, Di1 aMagnuson, John, J.1 aPavelsky, Tamlin1 aPiccolroaz, Sebastiano1 aRobertson, Dale, M.1 aSteele, Bethel, G.1 aTom, Manu1 aWeyhenmeyer, Gesa, A.1 aWoolway, Iestyn1 aXenopoulos, Marguerite, A.1 aYang, Xiao uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024WR03904202343nas a2200217 4500008004100000245011300041210006900154260001200223490000700235520161700242653001501859653001301874653001401887653001701901653001001918100002401928700002901952700001601981700003301997856009502030 2024 eng d00aAntarctic lake viromes reveal potential virus associated influences on nutrient cycling in ice-covered lakes0 aAntarctic lake viromes reveal potential virus associated influen c09/20240 v153 a

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.

10aAntarctica10abacteria10alimnology10ametagenomics10avirus1 aRobinson, David, M.1 aMorgan-Kiss, Rachael, M.1 aWang, Zhong1 aTakacs-Vesbach, Cristina, D. uhttps://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1422941/full