Supraglacial streams form annually during the melt season, transporting dissolved solutes from the melting ice and snowpack to subglacial flow paths and the glacier terminus. Although nutrient and carbon processing has been documented in other supraglacial environments (cryoconite holes, snowpack), little work has examined the potential for in-stream nutrient retention in supraglacial streams. Here we carried out a solute nutrient injection experiment to quantify NH3+, PO43−and labile dissolved organic carbon (DOC) retention in a supraglacial stream. The experiment was performed on a 100 m stream reach on Mendenhall Glacier, an outlet glacier on the Juneau Icefield, southeastern Alaska, USA. The study stream contained two distinct reaches of equal length. The first reach had a lower velocity (0.04 ms−1) and contained abundant gravel sediment lining the ice–water interface, while the second reach was devoid of bedload sediment and had an order-of-magnitude higher velocity. At the end of the second reach, the stream emptied into a moulin, which is typical of supraglacial streams on this and other temperate glaciers. We found that N and P were transported largely conservatively, although NO3−increased along the reach, suggestive of nitrification. Labile DOC was retained slightly within the stream, although rates were low relative to the travel times observed within the supraglacial stream. Although our findings show that these streams have low processing rates, measurable in-stream nitrification and dissolved organic matter uptake within this biologically unfavorable environment suggests that supraglacial streams with longer residence times and abundant fine substrate have the potential to modify and retain nutrients during transport to the glacier terminus.

As anthropogenic disturbance continues to degrade wetland condition in many geographic areas, it is imperative to inventory wetland functions to monitor potential loss of associated ecosystem services. Field-based functional assessments are resource intensive, prohibiting their widespread application at landscape scales. This obstacle can be avoided by basing functional assessments on publicly available remote sensed data. This pilot study examined the use of Watershed-based Preliminary Assessment of Wetland Function (W-PAWF) in the assessment of wetland restoration sites. W-PAWF was used to assess 15 depressional wetlands in the US Mid-Atlantic Coastal Plain. These sites spanned a human alteration gradient (i.e., natural wetlands, restored wetlands, and prior-converted croplands) to determine the sensitivity of the assessment method to variation in the assemblage and performance of wetland functions. Field-based rapid assessment methods were used to verify the W-PAWF assessment and detect potential functional gaps of importance to wetland restoration. Results indicate that W-PAWF can differentiate varying levels of restoration condition, but refinement will be necessary to assess functional restoration goals related to biogeochemistry and water quality. An evaluation of the field-based methods and an alternate remote functional assessment system suggest the potential for these functional characteristics to be incorporated in future iterations of the W-PAWF.

Wetlands are known to provide a myriad of vital ecosystem functions and services, which may be under threat from a changing climate. However, these effects may not be homogenous across ecosystem functions, wetland types, ecoregions, or meso‐scale watersheds, making broad application of the same management techniques inappropriate. Here, we present a relative wetland vulnerabilities framework, applicable across a range of spatial and temporal scales, to assist in identifying effective and robust management strategies in light of climate change. We deconstruct vulnerability into dimensions of exposure and sensitivity/adaptive capacity, and identify relevant measures of these as they pertain to the attributes of wetland extent and plant community composition. As a test of the framework, we populate it with data for three primary hydrogeomorphic wetland types (riverine, slope, and depression) in seven small watersheds across four ecoregions (Ridge and Valley, Piedmont, Unglaciated Plateau, and Glaciated Plateau) in the Susquehanna River watershed in Pennsylvania. We use data generated from the SRES A2 emissions experiment and MRI‐CGCM2.3.2 climate model as input to the Penn State Integrated Hydrologic Model to simulate future exposure to altered hydrologic conditions in our seven watersheds, as expressed in two hydrologic metrics: % time groundwater levels occur in the upper 30 cm (rooting zone) during the growing season, and median difference between spring and summer mean water levels. We then examine the spatial and temporal scales at which each of the components of vulnerability (exposure and sensitivity/adaptive capacity) shows significant relative differences. Overall, we find that relative differences in exposure persist at a very fine spatial grain, exhibiting high variability even among individual watersheds in a given ecoregion. For temporal scale, we find strong seasonal but weak annual relative differences in exposure resulting from a magnification of summer dry‐down combined with winter and spring wet periods becoming wetter. Sensitivities/adaptive capacities show significant differences among wetland types. A comparison between our anticipated hydrologic alterations under climate change and historical changes in hydrology due to anthropogenic disturbance indicates potential shifts in hydrologic patterns that are far beyond anything that wetland managers have experienced in the past.

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