Morphology-dependent water budgets and nutrient fluxes in Arctic thaw ponds
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Full Publication: https://doi.org/10.1002/ppp.1804Product Type: Journal Article
Year: 2014
Authors: Koch, J. C., K. Gurney, and M. S. Wipfli
Suggested Citation:
Koch, J. C., K. Gurney, and M. S. Wipfli. 2014. Morphology-dependent water budgets and nutrient fluxes in Arctic thaw ponds. Permafrost and Periglacial Processes 25(2):79-93. doi:10.1002/ppp.1804
Abstract
Thaw ponds on the Arctic Coastal Plain of Alaska are productive ecosystems, providing habitat and food resources for many fish and bird species. Permafrost in this region creates unique pond morphologies: deep troughs, shallow low-centred polygons (LCPs) and larger coalescent ponds. By monitoring seasonal trends in pond volume and chemistry, we evaluated whether pond morphology and size affect water temperature and desiccation, and nitrogen (N) and phosphorus (P) fluxes. Evaporation was the largest early-summer water flux in all pond types. LCPs dried quickly and displayed high early-summer nutrient concentrations and losses. Troughs consistently received solute-rich subsurface inflows, which accounted for 12 to 42 per cent of their volume and may explain higher P in the troughs. N to P ratios increased and ammonium concentrations decreased with pond volume, suggesting that P and inorganic N availability may limit ecosystem productivity in older, larger ponds. Arctic summer temperatures will likely increase in the future, which may accelerate mid-summer desiccation. Given their morphology, troughs may remain wet, become warmer and derive greater nutrient loads from their thawing banks. Overall, seasonal- to decadal-scale warming may increase ecosystem productivity in troughs relative to other Arctic Coastal Plain ponds.
Keywords: Arctic Coastal Plain, permafrost, ponds, climate warming, ecosystem productivity
Annotation
Thaw ponds on the Arctic Coastal Plain of Alaska are productive ecosystems, providing habitat and food resources for many fish and bird species. Because the pond ecosystems have sensitive water and nutrient budgets and morphologies, climate change may significantly alter their occurrence, extent and productivity. If the large populations of fish and migrating birds that rely on the invertebrate resources from small ponds are unable to adapt to these temporal shifts, their breeding success and population sizes may be negatively impacted, making them more vulnerable to anthropogenic impacts.