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1. Lake snow removal experiment phytoplankton community data, under ice, 2019-2021

   https://doi.org/10.6073/pasta/f6e271634a04819e25bc7c913cd67155  

   Socha, Ellen (January 2022, Environmental Data Initiative)

   Although it is a historically understudied season, winter is now recognized as a time of biological activity and relevant to the annual cycle of north-temperate lakes. Emerging research points to a future of reduced ice cover duration and changing snow conditions that will impact aquatic ecosystems. The aim of the study was to explore how altered snow and ice conditions, and subsequent changes to under-ice light environment, might impact ecosystem dynamics in a north, temperate bog lake in northern Wisconsin, USA. This dataset resulted from a snow removal experiment that spanned the periods of ice cover on South Sparkling Bog during the winters of 2019, 2020, and 2021. During the winters 2020 and 2021, snow was removed from the surface of South Sparkling Bog using an ARGO ATV with a snow plow attached. The 2019 season served as a reference year, and snow was not removed from the lake. This dataset represents phytoplankton community samples (pooled epilimnion and hypolimnion samples representative of 7 m water column) both under-ice and during some shoulder-season (open water) dates. Samples were collected into amber bottles and preserved with Lugol's solution before they were sent to Phycotech Inc. (St. Joseph MI, USA) for phytoplankton taxonomic identification and quantification. 

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2. Under Ice and Early Summer Phytoplankton Dynamics in Two Arctic Lakes with Differing DOC

   https://doi.org/10.1029/2020JG005972  

   Hazuková, V.; Burpee, B. T.; McFarlane‐Wilson, I.; Saros, J. E. (April 2021, Journal of Geophysical Research: Biogeosciences)

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3. Production of ice-nucleating particles (INPs) by fast-growing phytoplankton

   https://doi.org/10.5194/acp-23-12707-2023  

   Thornton, Daniel C_O; Brooks, Sarah D; Wilbourn, Elise K; Mirrielees, Jessica; Alsante, Alyssa N; Gold-Bouchot, Gerardo; Whitesell, Andrew; McFadden, Kiana (January 2023, Atmospheric Chemistry and Physics)

   Sea spray aerosol contains ice-nucleating particles (INPs), which affect the formation and properties of clouds. Here, we show that aerosols emitted from fast-growing marine phytoplankton produce effective immersion INPs, which nucleate at temperatures significantly warmer than the atmospheric homogeneous freezing (−38.0 ∘C) of pure water. Aerosol sampled over phytoplankton cultures grown in a Marine Aerosol Reference Tank (MART) induced nucleation and freezing at temperatures as high as −15.0 ∘C during exponential phytoplankton growth. This was observed in monospecific cultures representative of two major groups of phytoplankton, namely a cyanobacterium (Synechococcus elongatus) and a diatom (Thalassiosira weissflogii). Ice nucleation occurred at colder temperatures (−28.5 ∘C and below), which were not different from the freezing temperatures of procedural blanks, when the cultures were in the stationary or death phases of growth. Ice nucleation at warmer temperatures was associated with relatively high values of the maximum quantum yield of photosystem II (ΦPSII), an indicator of the physiological status of phytoplankton. High values of ΦPSII indicate the presence of cells with efficient photochemistry and greater potential for photosynthesis. For comparison, field measurements in the North Atlantic Ocean showed that high net growth rates of natural phytoplankton assemblages were associated with marine aerosol that acted as effective immersion INPs at relatively warm temperatures. Data were collected over 4 d at a sampling station maintained in the same water mass as the water column stabilized after deep mixing by a storm. Phytoplankton biomass and net phytoplankton growth rate (0.56 d−1) were greatest over the 24 h preceding the warmest mean ice nucleation temperature (−25.5 ∘C). Collectively, our laboratory and field observations indicate that phytoplankton physiological status is a useful predictor of effective INPs and more reliable than biomass or taxonomic affiliation. Ocean regions associated with fast phytoplankton growth, such as the North Atlantic during the annual spring bloom, may be significant sources of atmospheric INPs. 

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4. Ecology under lake ice

   https://doi.org/10.1111/ele.12699  

   Hampton, Stephanie E.; Galloway, Aaron W.; Powers, Stephen M.; Ozersky, Ted; Woo, Kara H.; Batt, Ryan D.; Labou, Stephanie G.; O'Reilly, Catherine M.; Sharma, Sapna; Lottig, Noah R.; et al (January 2017, Ecology Letters)
5. Platelet Ice Under Arctic Pack Ice in Winter

   https://doi.org/10.1029/2020GL088898  

   Katlein, Christian; Mohrholz, Volker; Sheikin, Igor; Itkin, Polona; Divine, Dmitry V.; Stroeve, Julienne; Jutila, Arttu; Krampe, Daniela; Shimanchuk, Egor; Raphael, Ian; et al (August 2020, Geophysical Research Letters)

   Abstract The formation of platelet ice is well known to occur under Antarctic sea ice, where subice platelet layers form from supercooled ice shelf water. In the Arctic, however, platelet ice formation has not been extensively observed, and its formation and morphology currently remain enigmatic. Here, we present the first comprehensive, long‐term in situ observations of a decimeter thick subice platelet layer under free‐drifting pack ice of the Central Arctic in winter. Observations carried out with a remotely operated underwater vehicle (ROV) during the midwinter leg of the MOSAiC drift expedition provide clear evidence of the growth of platelet ice layers from supercooled water present in the ocean mixed layer. This platelet formation takes place under all ice types present during the surveys. Oceanographic data from autonomous observing platforms lead us to the conclusion that platelet ice formation is a widespread but yet overlooked feature of Arctic winter sea ice growth. 

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