McMurdo Dry Valleys Biological responses to landscape change in the McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys, Antarctica, are experiencing rapid landscape scale change including increased glacial melt, the expansion of water tracks, thermokarst formation, an increase in the extent of the soil active layer, lake level rise, and altered stream flow. The impacts of these changes for biological communities are currently unknown. The goal of this study was to conduct surveys and experiments in three Dry Valley soil habitats that are expected to undergo change: water tracks, lake margins, and active layer profiles. Specifically, samples were collected from: 1) transects spanning dry-wet-dry soils in two water tracks in different lake basins, including three transects from each of three reaches for each water track, 2) experiments in which water and varying levels of salt were added to dry soils immediately adjacent to water tracks, 3) transects in lake margin soils in two different lake basins, including four transects perpendicular to each lake that span wet-to-dry soils, 4) experiments in which sterilized and non-sterilized lake water were added to dry soils adjacent to lakes, 5) the soil active layer from a total of eight soil pits in two different lake basins that were sampled at 5cm increments of depth, from the surface to 30cm or the permafrost, whichever was encountered first, and 6) experiments in which soils from the bottom of the soil active layer were moved to the upper layer and vice versa. Bacterial communities were sequenced for each sample and edaphic characteristics were measured for a subset of samples.