The Biodiversity and biogeochemistry of cryoconite holes from McMurdo Dry Valley glaciers, Antarctica

Once thought of as inert, ice has been increasingly recognized as a habitat suitable for life The landscape of the MCMurdo Dry Valleys (MCM) of Antarctica is dominated by glaciers, and glacier melt is the primary water source for life in soils, streams, and lakes. The glaciers, despite their cold and lifeless appearance, offer functioning habitats for life. The major objective of this study was to examine biogeochemical characteristics of miniecosystems present in cryoconite holes and to determine links to other components (soils, streams, and lakes) of the dry valley landscape. We examined cryoconite holes from 5 glaciers spanning the length of Taylor Valley, one of many valleys in the MCM. Cryoconite biotic communities were composed of the same species observed in streams and takes, namely, cyanobacteria (Chlorococcus, Chroococcus, Crinalium, Oscillatoria, Nostoc, and Sprirulina), rotifers (Philodina gregaria and Cephalodella catellina), tardigrades (Acutuncus antarcticus and Hypsibius spp.), and ciliates. Biotic communities did not reflect the composition of the immediately surrounding environments, suggesting the effects of eolian mixing and transport of sediments and biota across the valley. Gradients of chemistry and biotic abundance in cryoconite holes reflected the position of each glacier in the valley. Nitrogen and organic carbon concentration patterns across glaciers potentially resulted from biological activities in cryoconite holes. Properties of holes were stable from one to the next sampling season, suggesting that changes of cryoconite, hole properties develop on longer than yearly time scales.