Skip to main content
Advanced Search

Filters: Tags: {"type":"Science Themes","name":"water, coasts and ice"} (X) > Categories: Publication (X)

315 results (24ms)   

View Results as: JSON ATOM CSV
This study sought to advance our understanding of the responses of large migratory whales and other marine wildlife to climate change by examining species-specific shifts in timing of migration and habitat use. We used long-term historical datasets to measure changes in timing of seasonal habitat use in the Gulf of Maine (GOM) ecosystem by North Atlantic right (Eubalaena glacialis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), and minke whales (Balaenoptera acutorostrata). Occupancy modeling, spatial analyses, and synthetic approaches evaluated changes in the seasonal habitat use by large migratory whales, changes in risk of whale interactions with human activities such as shipping and fishing...
Abstract: We examine long-term streamflow and mass balance data from two Alaskan glaciers located in climatically distinct basins: Gulkana Glacier, a continental glacier located in the Alaska Range, and Wolverine Glacier, a maritime glacier located in the Kenai Mountains. Over the 1966–2011 study interval, both glaciers lost mass, primarily as a result of summer warming, and streamflow increased in both basins. We estimate total glacier runoff via summer mass balance and quantify the fraction of runoff related to annual mass imbalances. In both climates, annual (net) mass balance contributes, on average, less than 20 % of total streamflow, substantially less than the fraction related to summer mass loss (>50 %),...
Abstract (from http://pubs.acs.org/doi/full/10.1021/acs.est.5b02685): Dissolved organic carbon (DOC) plays a fundamental role in the biogeochemistry of glacier ecosystems. However, the specific sources of glacier DOC remain unresolved. To assess the origin and nature of glacier DOC, we collected snow from 10 locations along a transect across the Juneau Icefield, Alaska extending from the coast toward the interior. The Δ14C-DOC of snow varied from −743 to −420‰ showing progressive depletion across the Icefield as δ18O of water became more depleted (R2 = 0.56). Older DOC corresponded to lower DOC concentrations in snow ( R2 = 0.31) and a decrease in percent humic-like fluorescence ( R2 = 0.36), indicating an overall...
Abstract (from http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2290.html): Over the next century, one of the largest contributions to sea level rise will come from ice sheets and glaciers calving ice into the ocean. Factors controlling the rapid and nonlinear variations in calving fluxes are poorly understood, and therefore difficult to include in prognostic climate-forced land-ice models. Here we analyse globally distributed calving data sets from Svalbard, Alaska (USA), Greenland and Antarctica in combination with simulations from a first-principles, particle-based numerical calving model to investigate the size and inter-event time of calving events. We find that calving events triggered by the brittle...
Abstract (from Valdose Zone): Infiltration and downward percolation of water in the vadose zone are important processes that can define the availability of water resources. We present an approach that provides insight into how periodic infiltration forcings at the land surface filter in a layered vadose zone in terms of changes in the timing and magnitude of hydrologic responses. To represent geologically realistic systems, we used vertical sequences of one-dimensional periodic solutions, where each solution represents a single soil in a layered profile. The overall approach is based on a linearized Richards equation and assumes that the effects on flow of continuous pressure head changes at soil interfaces are...
Abstract (from http://link.springer.com/article/10.1007%2Fs12237-013-9694-0): Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared...
Abstract: Processes that influence habitat selection in landscapes involve the interaction of habitat composition and configuration and are particularly important for species with complex life cycles. We assessed the relative influence of landscape spatial processes and local habitat characteristics on patterns in the distribution and abundance of spawning steelhead ( Oncorhynchus mykiss), a threatened salmonid fish, across ~15,000 stream km in the John Day River basin, Oregon, USA. We used hurdle regression and a multi-model information theoretic approach to identify the relative importance of covariates representing key aspects of the steelhead life cycle (e.g., site access, spawning habitat quality, juvenile...
Abstract (from EGU): The General Lake Model (GLM) is a onedimensional open-source code designed to simulate the hydrodynamics of lakes, reservoirs, and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of researchers using sensors to understand lake functioning and address questions about how lakes around the world respond to climate and land use change. The scale and diversity of lake types, locations, and sizes, and the expanding observational datasets created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management questions relevant to the GLEON community....
Abstract (from http://iopscience.iop.org/1748-9326/9/5/055005): Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon (DOC). Characterizing DOC in Mendenhall Glacier outflow (southeast Alaska) we document a seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as a ubiquitous feature of glacier outflow. We observed no systematic depletion in Δ 14 C-DOC with increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, δ 13 C-DOC, Δ 14 C-DOC and fluorescence signatures appear to have been influenced by runoff from vegetated hillslopes above the glacier...
Abstract (from SpringerLink): Poor condition of many streams and concerns about future droughts in the arid and semi-arid western USA have motivated novel restoration strategies aimed at accelerating recovery and increasing water resources. Translocation of beavers into formerly occupied habitats, restoration activities encouraging beaver recolonization, and instream structures mimicking the effects of beaver dams are restoration alternatives that have recently gained popularity because of their potential socioeconomic and ecological benefits. However, beaver dams and dam-like structures also harbor a history of social conflict. Hence, we identified a need to assess the use of beaver-related restoration projects...
The increasing availability of climate projections provides natural resource managers and scientists with a number of scenarios from which to estimate variability in hydrologic response to future climatic conditions. This presents a need for consistent and efficient conversion of climate data into model-ready format, archiving and indexing of model simulation results, and the visualization and summation of model simulation results. Furthermore, decision-makers need this information at specific locations and for specific periods of record to effectively manage their water resources. This final report summarizes a collaborative effort to help address these issues through the construction of the Monthly Water Balance...
Abstract (from http://link.springer.com/article/10.1007/s10745-016-9822-0): Complex systems, such as ocean currents, occur at multiple temporal and physical scales require simultaneous analysis across a range of geographic scales. Presently, there are few available nearshore current maps or models accessible to managers or the public in Hawai'i despite the fact that predicting nearshore currents and processes is important for understanding many other social-ecological interactions. Maps of coastal ocean currents are difficult to create because of constant change and the limited availability of nearshore data. Maps are symbols of our collective knowledge frameworks, representing various geographic areas and features...
Climate change will affect the beneficial uses of streamflow, which include supplying freshwater for irrigation and domestic needs, providing for traditional and customary Hawaiian practices, and maintaining habitat for native stream fauna. Statistical models were developed to estimate surface-water availability during low-flow conditions for varying rainfall conditions. Results of this study include a spatial understanding of changes in low flows and usable stream habitat on Maui for a range of projected rainfall conditions for the late 21st century. This analysis indicates that stream responses to rainfall vary spatially in Hawai‘i. For example, a 10-percent decrease in rainfall may result in a 7% decrease in...
What will the rivers of the Pacific Northwest look like in the future? Will they be stable or unstable? Will the waters be cold and clear or warm and muddy? Will they have salmon or other species? These questions motivated our two-year study of climate warming effects on headwater streams draining the Cascade Mountains. Using a novel combination of snow, geohydrology, and sediment transport models we assessed the vulnerability of stream channels to changing peak streamflow. Our snow modeling shows that with just a 2°C warming, snowfall shifts to rainfall at all elevations, peak snowpacks occur over two months earlier, and snowpacks are reduced by over half of historical values. Our geohydrology modeling shows that...