02587nas a2200313   4500008004100000022001400041245012700055210006900182260001200251300001100263520145800274653001701732653001401749653000801763653001901771653001501790100002301805700001801828700001501846700002401861700002501885700003301910700002901943700001701972700002201989700002102011700002102032856022002053       2024                        eng d  a0954-102000aMcMurdo Dry Valley lake edge ‘moats’: The ecological intersection between terrestrial and aquatic polar desert habitat0 aMcMurdo Dry Valley lake edge moats The ecological intersection b  c04/2024  a1 - 173 a<p>Aquatic ecosystems - lakes, ponds and streams - are hotspots of biodiversity in the cold and arid environment of Continental Antarctica. Environmental change is expected to increasingly alter Antarctic aquatic ecosystems and modify the physical characteristics and interactions within the habitats that they support. Here, we describe physical and biological features of the peripheral &lsquo;moat&rsquo; of a closed-basin Antarctic lake. These moats mediate connectivity amongst streams, lake and soils. We highlight the cyclical moat transition from a frozen winter state to an active open-water summer system, through refreeze as winter returns. Summer melting begins at the lakebed, initially creating an ice-constrained lens of liquid water in November, which swiftly progresses upwards, creating open water in December. Conversely, freezing progresses slowly from the water surface downwards, with water at 1 m bottom depth remaining liquid until May. Moats support productive, diverse benthic communities that are taxonomically distinct from those under the adjacent permanent lake ice. We show how ion ratios suggest that summer exchange occurs amongst moats, streams, soils and sub-ice lake water, perhaps facilitated by within-moat density-driven convection. Moats occupy a small but dynamic area of lake habitat, are disproportionately affected by recent lake-level rises and may thus be particularly vulnerable to hydrological change.</p>10aconnectivity10aecosystem10aice10amicrobial mats10atransition1 aStone, Michael, S.1 aDevlin, Shawn1 aHawes, Ian1 aWelch, Kathleen, A.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D.1 aMorgan-Kiss, Rachael, M.1 aAdams, Byron1 aBarrett, John, E.1 aPriscu, John, C.1 aDoran, Peter, T.  uhttps://www.cambridge.org/core/journals/antarctic-science/article/mcmurdo-dry-valley-lake-edge-moats-the-ecological-intersection-between-terrestrial-and-aquatic-polar-desert-habitats/31D94DD51E651603482A3AE6E8A52A5702753nas a2200325   4500008004100000022001400041245011500055210007300170260001200243300001800255490000800273520178400281653001002065653001402075653001602089653000802105653001002113653001002123653001402133653001102147100002802158700002102186700003302207700002202240700002202262700002402284700002902308700002102337856006902358       2021                        eng d  a2169-895300aYear‐round and long‐term phytoplankton dynamics in Lake Bonney, a permanently ice‐covered Antarctic lake0 aYear‐round and long‐term phytoplankton dynamics in Lake Bonney a  c04/2021  ae2020JG0059250 v1263 a<p>Lake Bonney (McMurdo Dry Valleys, east Antarctica) represents a year‐round refugium for life adapted to permanent extreme conditions. Despite intensive research since the 1960s, due to the logistical constraints posed by 4‐months of 24‐h darkness, knowledge of how the resident photosynthetic microorganisms respond to the polar winter is limited. In addition, the lake level has risen by more than 3 m since 2004: impacts of rapid lake level rise on phytoplankton community structure is also poorly understood. From 2004 to 2015 an in situ submersible spectrofluorometer (bbe FluoroProbe) was deployed in Lake Bonney during the austral summer to quantify the vertical structure of four functional algal groups (green algae, mixed algae, and cryptophytes, cyanobacteria). During the 2013&ndash;2014 field season the Fluoroprobe was mounted on autonomous cable‐crawling profilers deployed in both the east and west lobes of Lake Bonney, obtaining the first daily phytoplankton profiles through the polar night. Our findings showed that phytoplankton communities were differentially impacted by physical and chemical factors over long‐term versus seasonal time scales. Following a summer of rapid lake level rise (2010&ndash;2011), an increase in depth integrated chlorophyll a (chl‐a) occurred in Lake Bonney caused by stimulation of photoautotrophic green algae. Conversely, peaks in chl‐a during the polar night were associated with an increase in mixotrophic haptophytes and cryptophytes. Collectively our data reveal that phytoplankton groups possessing variable trophic abilities are differentially competitive during seasonal and long‐term time scales owing to periods of higher nutrients (photoautotrophs) versus light/energy limitation (mixotrophs).</p>10aalgae10aAntarctic10afluorometry10aice10alakes10alight10aprofiling10awinter1 aPatriarche, Jeffrey, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aWinslow, Luke, A.1 aMyers, Krista, F.1 aBuelow, Heather, N.1 aMorgan-Kiss, Rachael, M.1 aDoran, Peter, T.  uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG005925