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Denitrification is a critical process regulating the removal of bioavailable nitrogen (N) from natural and human-altered systems. While it has been extensively studied in terrestrial, freshwater, and marine systems, there has been limited communication among denitrification scientists working in these individual systems. Here, we compare rates of denitrification and controlling factors across a range of ecosystem types. We suggest that terrestrial, freshwater, and marine systems in which denitrification occurs can be organized along a continuum ranging from (1) those in which nitrification and denitrification are tightly coupled in space and time to (2) those in which nitrate production and denitrification are relatively...
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Watersheds draining the Arctic Coastal Plain (ACP) of Alaska are dominated by permafrostand snowmelt runoff that create abundant surface storage in the form of lakes, wetlands, and beaded streams. These surface water elements compose complex drainage networks that affect aquatic ecosystem connectivity and hydrologic behavior. The 4676 km2 Fishand Creek drainage basin is composed of three watersheds that represent a gradient of theACP landscape with varying extents of eolian, lacustrine, and fluvial landforms. In each watershed, we analyzed 2.5-m-resolution aerial photography, a 5-m digital elevationmodel, and river gauging and climate records to better understand ACP watershed structureand processes. We show that...
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It is well recognized that the climate is warming in response to anthropogenic emission of greenhouse gases. Over the last decade, this has had a warming effect on lakes. Water clarity is also known to effect water temperature in lakes. What is unclear is how a warming climate might interact with changes in water clarity in lakes. As part of a project at the USGS Office of Water Information, several water clarity scenarios were simulated for lakes in Wisconsin to examine how changing water clarity interacts with climate change to affect lake temperatures at a broad scale. This data set contains the following parameters: year, WBIC, durStrat, max_schmidt_stability, mean_schmidt_stability_JAS, mean_schmidt_stability_July,...
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It is well recognized that the climate is warming in response to anthropogenic emission of greenhouse gases. Over the last decade, this has had a warming effect on lakes. Water clarity is also known to effect water temperature in lakes. What is unclear is how a warming climate might interact with changes in water clarity in lakes. As part of a project at the USGS Office of Water Information, several water clarity scenarios were simulated for lakes in Wisconsin to examine how changing water clarity interacts with climate change to affect lake temperatures at a broad scale. This data set contains the following parameters: year, WBIC, durStrat, max_schmidt_stability, mean_schmidt_stability_JAS, mean_schmidt_stability_July,...
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Interactions and feedbacks between abundant surface waters and permafrost fundamentally shapelowland Arctic landscapes. Sublake permafrost is maintained when the maximum ice thickness (MIT) exceedslake depth and mean annual bed temperatures (MABTs) remain below freezing. However, decliningMIT since the1970s is likely causing talik development below shallow lakes. Here we show high-temperature sensitivity towinter ice growth at the water-sediment interface of shallow lakes based on year-round lake sensor data.Empirical model experiments suggest that shallow (1m depth) lakes have warmed substantially over the last30years (2.4°C), withMABT above freezing5 of the last 7years.This is incomparison to slower ratesofwarming...
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This layer represents the lakes in the Crown of the Continent with a 50km buffer. This layer has been produced by merging the "WATERBODY_2" shapefiles from relevant NHN folders obtained from GeoBase - National Hydro Network (NHN) for Canada within the CCE and the "NHDWaterbody" shapefile for Montana, US. This dataset was developed by the Crown Managers Partnership, as part of a transboundary collaborative management initiative for the Crown of the Continent Ecosystem, based on commonly identified management priorities that are relevant at the landscape scale. The CMP is collaborative group of land managers, scientists, and stakeholder in the CCE. For more information on the CMP and its collaborators, programs,...
Synopsis: One recent study examining Eurasian watermilfoil (Myriophyllum spicatum L., hereafter milfoil) invasions using landscape-level variables found that the amount of forest land cover in the catchment is consistently negatively related to milfoil presence (Buchan and Padilla, 2000). These results suggest that further research is needed to examine the relationships between natural and anthropogenic landscape features and macrophyte cover. The ability of lake and landscape features to predict a variety of macrophyte cover metrics using 54 north temperate lakes were examined. Univariate regression analyses demonstrated that these macrophyte cover metrics are predicted by a wide range of predictor variables, most...
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Lakes are dominant and diverse landscapefeatures in the Arctic, but conventional land coverclassification schemes typically map them as a singleuniform class. Here, we present a detailed lake-centricgeospatial database for an Arctic watershed in northernAlaska. We developed a GIS dataset consisting of 4362lakes that provides information on lake morphometry,hydrologic connectivity, surface area dynamics,surrounding terrestrial ecotypes, and other importantconditions describing Arctic lakes. Analyzing thegeospatial database relative to fish and bird survey datashows relations to lake depth and hydrologic connectivity,which are being used to guide research and aid in themanagement of aquatic resources in the NationalPetroleum...
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The Arctic Coastal Plain (ACP) of northern Alaskaconsists of an extremely low gradient, lake-richlandscape that is characterized by a complex networkof aquatic habitats and surface features stronglyinfluenced by permafrost dynamics. Much is unknownabout the form, function, and ecological conditions inthis unique hydrologic setting. Amplified climatechange and landscape responses in the Arctic furthercomplicate the capacity to separate natural variabilityfrom land use effects that may occur with petroleumdevelopment. A comprehensive, multi-disciplinaryreview and analysis of recent studies and initialinventory and monitoring in the Fish Creek watershedon the ACP provided guidance to develop a frameworkfor future aquatic...
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When resources are spatially and temporally variable, consumers can increasetheir foraging success by moving to track ephemeral feeding opportunitiesas these shift across the landscape; the best examples derive from herbivore–plant systems, where grazers migrate to capitalize on the seasonal waves ofvegetation growth. We evaluated whether analogous processes occur in watershedssupporting spawning sockeye salmon (Oncorhynchus nerka), askingwhether seasonal activities ofpredators and scavengers shift spatial distributionsto capitalize on asynchronous spawning among populations of salmon. Bothglaucous-winged gulls and coastal brown bears showed distinct shifts in theirspatial distributions over the course of the summer,...
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How local geomorphic and hydrologic features mediate the sensitivity of stream thermal regimesto variation in climatic conditions remains a critical uncertainty in understanding aquatic ecosystem responsesto climate change.We used stable isotopes of hydrogen and oxygen to estimate contributions of snow and rainfallto 80 boreal streams and show that differences in snow contribution are controlled by watershed topography.Time series analysis of streamthermal regimes revealed that streams in rain-dominated, low-elevation watershedswere 5–8 times more sensitive to variation in summer air temperature compared to streams draining steepertopography whose flows were dominated by snowmelt. This effect wasmore pronounced...
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Beaded streams are widespread in permafrost regionsand are considered a common thermokarst landform.However, little is known about their distribution, how andunder what conditions they form, and how their intriguingmorphology translates to ecosystem functions and habitat.Here we report on a circum-Arctic survey of beaded streamsand a watershed-scale analysis in northern Alaska using remotesensing and field studies.We mapped over 400 channelnetworks with beaded morphology throughout the continuouspermafrost zone of northern Alaska, Canada, and Russiaand found the highest abundance associated with mediumto high ground-ice content permafrost in moderately slopingterrain. In one Arctic coastal plain watershed, beaded...
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This tabular data set represents the presence of six National Hydrography Dataset (NHD) high resolution waterbody types compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. The six types of waterbodies presented here are: playa, ice mass, lake/pond, reservoir, swamp/marsh, and estuary. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data is the NHDPlus high resolution waterbodies produced by USGS , 2015. Units are percent. Reach catchment information characterizes data at the local scale....
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This dataset is a component of a complete package of products from the Connect the Connecticut project. Connect the Connecticut is a collaborative effort to identify shared priorities for conserving the Connecticut River Watershed for future generations, considering the value of fish and wildlife species and the natural ecosystems they inhabit. Click here to download the full data package, including all documentation. These datasets represent aquatic core areas and aquatic buffers, in combination with terrestrial cores and connectors they spatially represent the ecological network derived from the CTR LCD project. Lotic cores: This set of lotic (river and stream) core areas, in combination with the lotic cores...
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It is well recognized that the climate is warming in response to anthropogenic emission of greenhouse gases. Over the last decade, this has had a warming effect on lakes. Water clarity is also known to effect water temperature in lakes. What is unclear is how a warming climate might interact with changes in water clarity in lakes. As part of a project at the USGS Office of Water Information, several water clarity scenarios were simulated for lakes in Wisconsin to examine how changing water clarity interacts with climate change to affect lake temperatures at a broad scale. This data set contains the following parameters: year, WBIC, durStrat, max_schmidt_stability, mean_schmidt_stability_JAS, mean_schmidt_stability_July,...
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Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since manyArctic lakes are shallow and ice grows thick (historically 2 m or greater), seasonal ice commonly freezes tothe lake bed (bedfast ice) by winter’s end. Bedfast ice fundamentally alters lake energy balance and meltoutprocesses compared to deeper lakes that exceed the maximum ice thickness (floating ice) and maintainperennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-out ofbedfast ice lakes occurred on average 17 days earlier (22 June) than ice-out on adjacent floating ice lakes (9July). Earlier ice-free conditions in bedfast ice lakes caused higher open-water evaporation,...
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In Arctic ecosystems, freshwater fish migrateseasonally between productive shallow water habitatsthat freeze in winter and deep overwinter refuge in riversand lakes. How these movements relate to seasonal hydrologyis not well understood.We used passive integratedtransponder tags and stream wide antennae to track1035 Arctic grayling in Crea Creek, a seasonally flowingbeaded stream on the Arctic Coastal Plain, Alaska. Migrationof juvenile and adult fish into Crea Creek peakedin June immediately after ice break-up in the stream. Fishthat entered the stream during periods of high flow andcold stream temperature traveled farther upstream thanthose entering during periods of lower flow and warmertemperature. We used generalized...
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Numerous studies utilizing remote sensing imagery and other methods have documented that thermokarst lakes are undergoing varied hydrological transitions in response to recent climate changes, from surface area expansion to drainage and evaporative desiccation. Here, we provide a synthesis of hydrological conditions for 376 lakes of mainly thermokarst origin across high-latitude North America. We assemble surface water isotope compositions measured during the past decade at five lake-rich landscapes including Arctic Coastal Plain (Alaska), Yukon Flats (Alaska), Old Crow Flats (Yukon), northwestern Hudson Bay Lowlands (Manitoba), and Nunavik (Quebec). These landscapes represent the broad range of thermokarst environments...
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Field measurements, satellite observations, and models document a thinning trend in seasonal Arcticlake ice growth, causing a shift from bedfast to floating ice conditions. September sea iceconcentrations in the Arctic Ocean since 1991 correlate well (r=+0.69, p<0.001) to this lakeregime shift. To understand how and to what extent sea ice affects lakes, we conducted modelexperiments to simulate winters with years of high (1991/92) and low (2007/08) sea ice extent forwhich we also had field measurements and satellite imagery characterizing lake ice conditions. Alakeice growth model forced with Weather Research and Forecasting model output produced a 7%decrease in lake ice growth when 2007/08 sea ice was imposed on...
We suggest an empirical approach for determining critical loads for inorganic nitrogen (N) deposition in wetfall to the central Rocky Mountains (USA). We define "critical loads" as a deposition amount above which natural resources can be negatively affected. The arithmetic average from 1992 to 1996 of annual inorganic N deposition in wetfall at the eight National Acid-Deposition Program (NADP) sites located at elevations >2500 m in the central Rocky Mountains ranged from 2.5 to 3.5 kg�ha-1�yr-1. In contrast, inorganic N deposition was <2.5 kg�ha-1�yr-1 at all 23 NADP sites below 2500 m in elevation. At the Niwot Ridge NADP site in the Colorado Front Range, a simple linear regression of inorganic N in wetfall with...
map background search result map search result map Aquatic Cores and Buffers, CT River Watershed Wisconsin Lake Temperature Metrics Decreasing Clarity Wisconsin Lake Temperature Metrics Increasing Clarity Wisconsin Lake Temperature Metrics Stable Clarity Lakes in the Crown of the Continent Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Percent of Watershed Covered by Waterbodies from NHD High Resolution Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate A lake-centric geospatial database to guide research and inform management decisions in an Arctic watershed in northern Alaska... Arctic sea ice decline contributes to thinning lake ice trend in northern Alaska A synthesis of thermokarst lake water balance in high-latitude regions of North America from isotope tracers Watershed geomorphology and snowmelt control stream thermal sensitivity to air temperature. Riding the crimson tide: mobile terrestrial consumers track phenological variation in spawning of an anadromous fish Drainage Network Structure and Hydrologic Behavior of Three Lake-Rich Watersheds on the Arctic Coastal Plain, Alaska Developing a Long-term Aquatic Monitoring Network Developing a Long-Term Aquatic Monitoring Network in a Complex Watershed of the Alaskan Arctic Coast Seasonal cues of Arctic grayling movement in a small Arctic stream: the importance of surface water connectivity Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate A lake-centric geospatial database to guide research and inform management decisions in an Arctic watershed in northern Alaska... Arctic sea ice decline contributes to thinning lake ice trend in northern Alaska A synthesis of thermokarst lake water balance in high-latitude regions of North America from isotope tracers Seasonal cues of Arctic grayling movement in a small Arctic stream: the importance of surface water connectivity Drainage Network Structure and Hydrologic Behavior of Three Lake-Rich Watersheds on the Arctic Coastal Plain, Alaska Developing a Long-term Aquatic Monitoring Network Developing a Long-Term Aquatic Monitoring Network in a Complex Watershed of the Alaskan Arctic Coast Watershed geomorphology and snowmelt control stream thermal sensitivity to air temperature. Riding the crimson tide: mobile terrestrial consumers track phenological variation in spawning of an anadromous fish Aquatic Cores and Buffers, CT River Watershed Lakes in the Crown of the Continent Wisconsin Lake Temperature Metrics Decreasing Clarity Wisconsin Lake Temperature Metrics Increasing Clarity Wisconsin Lake Temperature Metrics Stable Clarity Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Percent of Watershed Covered by Waterbodies from NHD High Resolution