Aufeis fields as novel groundwater‐dependent ecosystems in the arctic cryosphere

Abstract

River aufeis (ow 0 fīse) are widespread features of the arctic cryosphere. They form when river channels become locally restricted by ice, resulting in cycles of water overflow and freezing and the accumulation of ice, with some aufeis attaining areas of $ 25 + km 2 and thicknesses of 6+ m. During winter, unfrozen sediments beneath the insulating ice layer provide perennial groundwater-habitat that is otherwise restricted in regions of continuous permafrost. Our goal was to assess whether aufeis facilitate the occurrence of groundwater invertebrate communities in the Arctic. We focused on a single aufeis ecosystem ($ 5 km 2 by late winter) along the Kuparuk River in arctic Alaska. Subsurface invertebrates were sampled during June and August 2017 from 50 3.5-cm diameter PVC wells arranged in a 5 × 10 array covering $ 40 ha. Surface invertebrates were sampled using a quadrat approach. We documented a rich assemblage of groundwater invertebrates (49 [43-54] taxa, X [95% confidence limits]) that was distributed below the sediment surface to a mean depth of $ 69 ± 2 cm (X ± 1 SE) throughout the entire well array. Although community structure differed significantly between groundwater and surface habitats, the taxa richness from wells and surface sediments (43 [35-48] taxa) did not differ significantly, which was surprising given lower richness in subsurface habitats of large, riverine gravel-aquifer systems shown elsewhere. This is the first demonstration of a rich and spatially extensive groundwater fauna in a region of continuous permafrost. Given the geographic extent of aufeis fields, localized groundwater-dependent ecosystems may be widespread in the Arctic.

Spatial and temporal dynamics of aufeis in the Tso Moriri basin, eastern Ladakh, India

“…72 In addition, potential attention so far. 28 The results of the accuracy assessment support that a machine learning approach is suitable to map icing/aufeis and that the method can be transferred to other regions. Unlike thresholds, deviations in spectral properties do not require manual adjustments and have little influence on the predictions of the model, if the training samples are representative of the target classes.…”

“…Nevertheless, remote sensing provides the opportunity to monitor such changes, despite data availability remaining the main obstacle for long‐term monitoring in the region. The widespread occurrence of aufeis in the Trans‐Himalaya 31 offers the opportunity not only to investigate the hydrology or physicomechanical process but also their role for river ecology, downstream habitats or local communities – aspects which have not received much attention so far 28 …”

“…Due to climate change, the number and extent of aufeis fields are declining in several cold regions. 23,25,26 Studies on aufeis have mainly been conducted in North America or Siberia, [27][28][29][30] while research in HMA is still in an exploratory phase, with only one inventory for the upper Indus basin (UIB). 31 This inventory comprises 3,700 aufeis fields, with most of them being located in the eastern parts of UIB, indicating that cold-arid conditions might be beneficial for their formation in high-altitude regions.…”

Datasets for research on groundwater flow and its interactions with surface water in an alpine catchment on the northeastern Tibetan Plateau, China

“…In the case of global warming, interactions between groundwater flow and surface water may cause the release of carbon trapped in permafrost and aggravate the greenhouse effect (Harlan, 1973;Solomon et al, 2007;Schaefer et al, 2011;Wisser et al, 2011;Mckenzie and Voss, 2013;Connolly et al, 2020;Behnke et al, 2021). Because of the heat released by the movement of groundwater in the subsurface layer and the thermal insulation effect of the surface ice layer, saturated sediments are not frozen year round and provide interstitial habitats for groundwater fauna (Schohl and Ettema, 1990;Clark and Lauriol, 1997;Alekseyev, 2015;Huryn et al, 2020;Terry et al, 2020). All these findings undoubtedly confirm the importance of groundwater flow in cold-region hydrological systems.…”

Aufeis as a Major Forcing Mechanism for Channel Avulsion and Implications of Warming Climate

“…Springs that feed aufeis accumulations tend to be sites of particularly dense aquatic and riparian vegetation and provide overwintering sites for fish including Arctic char (Salvelinus alpinus) (Childers et al, 1977). Huryn et al (2021) found that aufeis facilitates the existence of rich and spatially extensive groundwater-dependent invertebrate communities with significantly different community structure than those present in surface habitats. River corridors in this tundra environment attract migratory songbirds (Winner, 2003), shorebirds (Johnson et al, 2007), waterfowl (Larned et al, 2012), and willow ptarmigan (Lagopus lagopus) (Christie et al, 2014), as well as moose (Alces alces) (Zhou et al, 2020) and other wildlife.…”