02991nas a2200229   4500008004100000245018700041210006900228260001200297490000700309520217100316653001802487653001102505653001602516653001402532653001802546653001102564100002102575700002202596700002402618700002402642856009502666       2024                        eng d00aDrifting along: Using diatoms to track the contribution of microbial mats to particulate organic matter transport in a glacial meltwater stream in the McMurdo Dry Valleys, Antarctica0 aDrifting along Using diatoms to track the contribution of microb  c05/20240 v153 a<p>Flow pulses mobilize particulate organic matter (POM) in streams from the surrounding landscape and streambed. This POM serves as a source of energy and nutrients, as well as a means for organismal dispersal, to downstream communities. In the barren terrestrial landscape of the McMurdo Dry Valleys (MDV) of Antarctica, benthic microbial mats occupying different in-stream habitat types are the dominant POM source in the many glacier-fed streams. Many of these streams experience daily flow peaks that mobilize POM, and diatoms recovered from underlying stream sediments suggest that mat-derived diatoms in the POM are retained there through hyporheic exchange. Yet, &lsquo;how much&rsquo; and &lsquo;when&rsquo; different in-stream habitat types contribute to POM diatom assemblages is unknown. To quantify the contribution of different in-stream habitat types to POM diatom assemblages, we collected time-integrated POM samples over four diel experiments, which spanned a gradient of flow conditions over three summers. Diatoms from POM samples were identified, quantified, and compared with dominant habitat types (i.e., benthic &lsquo;orange&rsquo; mats, marginal &lsquo;black&rsquo; mats, and bare sediments). Like bulk POM, diatom cell concentrations followed a clockwise hysteresis pattern with stream discharge over the daily flow cycles, indicating supply limitation. Diatom community analyses showed that different habitat types harbor distinct diatom communities, and mixing models revealed that a substantial proportion of POM diatoms originated from bare sediments during baseflow conditions. Meanwhile, orange and black mats contribute diatoms to POM primarily during daily flow peaks when both cell concentrations and discharge are highest, making mats the most important contributors to POM diatom assemblages at high flows. These observations may help explain the presence of mat-derived diatoms in hyporheic sediments. Our results thus indicate a varying importance of different in-stream habitats to POM generation and export on daily to seasonal timescales, with implications for biogeochemical cycling and the local diatom metacommunity.</p>10acyanobacteria10adiatom10aflow regime10ahydrology10amicrobial mat10aNostoc1 aStanish, Lee, F.1 aKohler, Tyler, J.1 aDarling, Joshua, P.1 aMcKnight, Diane, M.  uhttps://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1352666/full02051nas a2200253   4500008004100000245010800041210006900149260001200218520110900230653001201339653001401351653002401365653001701389653001901406653001701425100002401442700002501466700002201491700002001513700002101533700002101554700001601575856020601591       2020                        eng d00aRemote characterization of photosynthetic communities in the Fryxell basin of Taylor Valley, Antarctica0 aRemote characterization of photosynthetic communities in the Fry  c03/20203 a<p>We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.</p>10aecology10ahydrology10aMcMurdo Dry Valleys10amicrobiology10aremote sensing10aspectroscopy1 aSalvatore, Mark, R.1 aBorges, Schuyler, R.1 aBarrett, John, E.1 aSokol, Eric, R.1 aStanish, Lee, F.1 aPower, Sarah, N.1 aMorin, Paul  uhttps://www.cambridge.org/core/journals/antarctic-science/article/remote-characterization-of-photosynthetic-communities-in-the-fryxell-basin-of-taylor-valley-antarctica/8576F6BB1BCFDCA8409F5EA96CA00C6F