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Abstract Riveraufeis(ow′ 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 someaufeisattaining areas of ~ 25 + km2and 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 whetheraufeisfacilitate the occurrence of groundwater invertebrate communities in the Arctic. We focused on a singleaufeisecosystem (~ 5 km2by 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,[95% confidence limits]) that was distributed below the sediment surface to a mean depth of ~ 69 ± 2 cm (± 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 ofaufeisfields, localized groundwater‐dependent ecosystems may be widespread in the Arctic.
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Greening of the boreal peatland food web: Periphyton supports secondary production in northern peatlands
Abstract Characterizing spatial and temporal variability of food web dynamics is necessary to predict how wetter and more nutrient‐rich conditions expected with climate change will influence the fate of organic matter within northern peatlands. The goals of this study were to (1) document spatial and temporal variability in the contribution of periphyton to peatland food webs using isotope analysis (13C and15N), and (2) quantify the influence of increased nutrient availability on primary and secondary production across a gradient of rich, moderate, and poor fen peatlands common to the northern boreal biome. We established replicatem2plots within each fen located in interior Alaska to quantify periphyton (algae and bacteria) and macroinvertebrate biomass with and without nutrient addition throughout a growing season (May–August). Stable isotope analysis showed that periphyton contributed= 65% of organic matter to the food web over time and across fens compared to= 7% from plants or detritus. The transfer of basal resources was reflected in an increase in herbivore biomass as algal biomass increased over time in all fens, followed by an increase in predatory macroinvertebrates during the latter part of the growing season. Furthermore, all measures of periphyton and macroinvertebrate biomass were enhanced by nutrient addition. These data provide insight into patterns of natural variation within the aquatic food web of boreal peatlands and show that basal resources within this ecosystem, which are generally considered to be “detritus‐based,” are actually driven by periphyton with minimal input from plant detrital pathways.
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- Award ID(s):
- 1651195
- PAR ID:
- 10452905
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography
- Volume:
- 66
- Issue:
- 5
- ISSN:
- 0024-3590
- Page Range / eLocation ID:
- p. 1743-1758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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