Digital Commons Network^™

Clues To The Medieval Destabilization Of The Nebraska Sand Hills, Usa, From Ancient Pocket Gopher Burrows, Rebecca L. Schmeisser, David B. Loope, David A. Wedin

Department of Earth and Atmospheric Sciences: Faculty Publications

The Nebraska Sand Hills are a stabilized dune field in the central United States that reflect past conditions of drought. The most recent drought, known as the Medieval Climatic Anomaly, occurred from A.D. 900 to A.D. 1300 and had an enormous effect on the thriving prairie ecosystem, which included large populations of the plains pocket gopher (Geomys bursarius). Burrows of these organisms across a paleosol-eolian sand boundary in the Sand Hills indicate abrupt climate change during the transition from stabilized to active dune field and from humid to arid conditions. Medieval gophers tunneled at greater depths below the …

Mitigation Under Section 404 Of The Clean Water Act: Where It Comes From, What It Means, Palmer Hough, Morgan Robertson

United States Environmental Protection Agency: Publications

The requirement to mitigate impacts to wetlands and streams is a frequently misunderstood policy with a long and complicated history. We narrate the history of mitigation since the inception of the Clean Water Act Section 404 permit program in 1972, through struggles between the US Environmental Protection Agency and the US Army Corps of Engineers, through the emerging importance of wetland conservation on the American political landscape, and through the rise of market-based approaches to environmental policy. Mitigation, as it is understood today, was not initially foreseen as a component of the Section 404 permitting program, but was adapted from …

Thresholds Of Climate Change In Ecosystems: Final Report, Synthesis And Assessment Product 4.2, Craig D. Allen, Charles Birkeland, F. Stuart Chapin, Iii, Peter M. Groffman, Glenn . R. Guntenspergen, Alan K. Knapp, A. David Mcguire, Patrick J. Mulholland, Debra P.C. Peters, Daniel D. Roby, George Sugihara

United States Geological Survey: Publications

As defined in this Synthesis and Assessment Report, ‘an ecological threshold is the point at which there is an abrupt change in an ecosystem quality, property, or phenomenon, or where small changes in one or more external conditions produce large and persistent responses in an ecosystem’.
Ecological thresholds occur when external factors, positive feedbacks, or nonlinear instabilities in a system cause changes to propagate in a domino-like fashion that is potentially irreversible. This report reviews threshold changes in North American ecosystems that are potentially induced by climatic change and addresses the significant challenges these threshold crossings impose on resource and …

Quantifying Equid Behavior—A Research Ethogram For Free-Roaming Feral Horses, Jason I. Ransom, Brian S. Cade

United States Geological Survey: Publications

Feral horses (Equus caballus) are globally distributed in free-roaming populations on all continents except Antarctica and occupy a wide range of habitats including forest, grassland, desert, and montane environments. The largest populations occur in Australia and North America and have been the subject of scientific study for decades, yet guidelines and ethograms for feral horse behavioral research are largely absent in the scientific literature. The U.S. Geological Survey (USGS) Fort Collins Science Center conducted research on the influences of the immunocontraceptive porcine zona pellucida (PZP) on feral horse behavior from 2003–2006 in three discrete populations in the American …

Climate Change And Water Resources Management: A Federal Perspective, Levi D. Brekke, Julie E. Kiang, J. Rolf Olsen, Roger S. Pulwarty, David A. Raff, D. Phil Turnipseed, Robert S. Webb, Kathleen D. White

United States Geological Survey: Publications

Many challenges, including climate change, face the Nation’s water managers. The Intergovernmental Panel on Climate Change (IPCC) has provided estimates of how climate may change, but more understanding of the processes driving the changes, the sequences of the changes, and the manifestation of these global changes at different scales could be beneficial. Since the changes will likely affect fundamental drivers of the hydrological cycle, climate change may have a large impact on water resources and water resources managers.

The purpose of this interagency report prepared by the U.S. Geological Survey (USGS), U.S. Army Corps of Engineers (USACE), Bureau of Reclamation …

Structured Decision Making As A Conceptual Framework To Identify Thresholds For Conservation And Management, Julien Martin, Michael C. Runge, James D. Nichols, Bruce C. Lubow, William L. Kendall2

United States Geological Survey: Staff Publications

Threshold and their relevance to conservation have become a major topic of discussion in the ecological literature. Unfortunately, in many cases the lack of a clear conceptual framework for thinking about thresholds in terms of a structured decision making process. The purpose of this framework is to promote a logical and transparent process for making informed decisions for conservation.

Specification of such a framework leads naturally to consideration of definitions and roles of different kinds of thresholds in the process. We distinguish among three categories of thresholds. Ecological thresholds are values of system state variables at which small changes bring …

Riparian And Associated Habitat Characteristics Related To Nutrient Concentrations And Biological Responses Of Small Streams In Selected Agricultural Areas, United States, 2003–04, Ronald B. Zelt, Mark D. Munn

United States Geological Survey: Publications

Physical factors, including both in-stream and riparian habitat characteristics that limit biomass or otherwise regulate aquatic biological condition, have been identified by previous studies. However, linking the ecological significance of nutrient enrichment to habitat or landscape factors that could allow for improved management of streams has proved to be a challenge in many regions, including agricultural landscapes, where many ecological stressors are strong and the variability among watersheds typically is large. Riparian and associated habitat characteristics were sampled once during 2003–04 for an intensive ecological and nutrients study of small perennial streams in five contrasting agricultural landscapes across the United …

Behavior And Reproductive Success Of Rock Sandpipers Breeding On The Yukon-Kuskokwim River Delta, Alaska, Matthew Johnson, Jesse R. Conklin, Branden L. Johnson, Brian J. Mccaffery, Susan M. Haig, Jeffrey R. Walters

United States Geological Survey: Staff Publications

We studied Rock Sandpiper (Calidris ptilocnemis) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers bred at our study site for ≥ 2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through …

Farming For The Future : Industry Practice Baselines, Danielle England, Susan Murphy-White, John Noonan, Marie Shanks, Jon Warren

Resource management technical reports

No abstract provided.

Markov Models For Linking Environments And Facies In Space And Time (Recent Arabian Gulf, Miocene Paratethys), Bernhard Riegl, Samuel J. Purkis

Marine & Environmental Sciences Faculty Articles

If, as comparative sedimentology maintains, knowledge of the Recent can sometimes be helpful to explain the past (and vice-versa), common quantitative denominators might exist between Recent and fossil systems. It may also be possible to describe dynamics and find linkages between space and time with a unique set of quantitative tools. To explore such conceptual links, spatial facies patterns mapped using satellite imagery were compared with temporal patterns in analogous ancient outcropping facies using Markov chains and graphs. Landsat and Ikonos satellite imagery was used to map benthic facies in a nearshore carbonate ramp (Ras Hasyan) and offshore platform system …

The Dilemma Of Disappearing Diatoms: Incorporating Diatom Dissolution Data Into Paleoenvironmental Modeling And Reconstruction, David B. Ryves, Richard W. Battarbee, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Taphonomic issues pose fundamental challenges for Quaternary scientists to recover environmental signals from biological proxies and make accurate inferences of past environments. The problem of microfossil preservation, specifically diatom dissolution, remains an important, but often overlooked, source of error in both qualitative and quantitative reconstructions of key variables from fossil samples, especially those using relative abundance data. A first step to tackling this complex issue is establishing an objective method of assessing preservation (here, diatom dissolution) that can be applied by different analysts and incorporated into routine counting strategies. Here, we establish a methodology for assessment of diatom dissolution under …

Significance Of The Trace Fossil Zoophycos In Pliocene Deposits, Antarctic Continental Margin (Andrill 1b Drill Core), Molly F. Miller, Ellen A. Cowan, Simon H. H. Nielsen

ANDRILL Research and Publications

Zoophycos is a complex three dimensional trace fossil that is abundant in deep ocean sediments worldwide, but has not been described previously from Cenozoic continental margin deposits of Antarctica. In the ANDRILL 1B core drilled through the north-west McMurdo ice shelf, Zoophycos occurs in a 17m thick unit of interglacial sediments bounded above and below by glacial surfaces of erosion. This unit was deposited during the transition from the relatively warm Early Pliocene characterized by productive open waters to the cooler Late Pliocene with fluctuating subpolar ice sheets. Globally, Late Cenozoic Zoophycos are most abundant at great depths (.1000 m), …

Ecosystem Jenga!, Natalie Umphlett, Tierney Brosius, Ramesh Laungani, Diandra L. Leslie-Pelecky

High Plains Regional Climate Center: Staff Publications

Students are often taught that ecosystems are "delicately balanced," But what. exactly, does this mean? How do we help students relate what they learn in the classroom about ecosystems to the world immediately around them?

As scientists who work closely with middle school students as part of a National Science Foundation-funded Graduate Fellows in K-12 Education program called Project Fulcrum. we have learned that abstract concepts, such as "delicately balanced ecosystem," are often not truly understood. We addressed this concern in a seventh-grade science classroom in Lincoln. Nebraska. by introducing students to locally threatened saline wetlands and the endangered Salt …

Effects Of Groundwater Development On Uranium: Central Valley, California, Usa, Bryant C. Jurgens, Miranda S. Fram, Kenneth Belitz, Karen R. Burow, Matthew K. Landon

United States Geological Survey: Staff Publications

Uranium (U) concentrations in groundwater in several parts of the eastern San Joaquin Valley, California, have exceeded federal and state drinking water standards during the last 20 years. The San Joaquin Valley is located within the Central Valley of California and is one of the most productive agricultural areas in the world. Increased irrigation and pumping associated with agricultural and urban development during the last 100 years have changed the chemistry and magnitude of groundwater recharge, and increased the rate of downward groundwater movement. Strong correlations between U and bicarbonate suggest that U is leached from shallow sediments by high …

Potential Export Of Unattached Benthic Macroalgae To The Deep Sea Through Wind Driven Langmuir Circulation, H. M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OES Faculty Publications

Carbon export to the deep sea is conventionally attributed to the sinking of open ocean phytoplankton. Here, we report a Langmuir supercell event driven by high winds across the shallow Great Bahama Bank that organized benthic non-attached macroalgae, Colpomenia sp., into visible windrows on the seafloor. Ocean color satellite imagery obtained before and after the windrows revealed a 588 km² patch that rapidly shifted from highly productive macroalgae to bare sand. We assess a number of possible fates for this macroalgae and contend that this event potentially transported negatively buoyant macroalgae to the deep Tongue of the Ocean …

Synergistic Effects Of Iron And Temperature On Antarctic Phytoplankton And Microzooplankton Assemblages, J. M. Rose, Y. Feng, G. R. Ditullio, R. B. Dunbar, C. E. Hare, P. A. Lee, M. Lohan, M. Long, W. O. Smith Jr., B. Sohst, S. Tozzi, Y. Zhang, D. A. Hutchins

OES Faculty Publications

Iron availability and temperature are important limiting factors for the biota in many areas of the world ocean, and both have been predicted to change in future climate scenarios. However, the impacts of combined changes in these two key factors on microbial trophic dynamics and nutrient cycling are unknown. We examined the relative effects of iron addition (+1 nM) and increased temperature (+4° C) on plankton assemblages of the Ross Sea, Antarctica, a region characterized by annual algal blooms and an active microbial community. Increased iron and temperature individually had consistently significant but relatively minor positive effects on total phytoplankton …

Geobiology: Evidence For Early Life On Earth And The Search For Life On Other Planets, Sherry L. Cady, Nora Noffke

OES Faculty Publications

Extensive research efforts in the subdisciplinary field of geobiology have focused on the interactions between Earth and life through time. As a consequence, gaps in our knowledge of Earth’s history are closing, and the search for life beyond Earth is expanding. A few examples of geobiology studies designed to advance our understanding of life on early Earth and to improve the chances of finding life on other planets are provided to highlight recent developments and research areas that are on the verge of new discoveries.

Observations Of The Transient Characteristics Of The Hydrological Balance, Matthew Czikowsky

Legacy Theses & Dissertations (2009 - 2024)

The impact of transient input events on the hydrological balance components are studied over a wide range of spatial and temporal scales. First, interception evaporation and energy-balance changes during and following precipitation events are examined at the site spatial and event temporal scale. Second, the hydrological response to spatial and seasonal changes in precipitation and evapotranspiration due to land cover changes are examined on the small-to-large watershed scale, covering the event to seasonal time scales.

Mercury Uptake By Aquatic Macrophytes In Urban And Rural Watersheds, Albany County, Ny, Bernd G. Neumann

Geology Theses and Dissertations

Plants growing in metalliferous soils may restrict metal uptake and transport depending on metal concentration, sediment characteristics, and plant species. As native plants are replaced by invasives, different patterns of metal cycling can occur, making continued study of this process important. Sediments and tissues of four aquatic plant species/genera: Phragmites australis (common reed); Iris versicolor (blueflag iris); Typha latifolia (broadleaf cattail); and genera Cyperus sp. (sedge) from three urban and two rural sites in Albany County, NY were analyzed for total mercury (Hg_­T) by cold vapor atomic absorption spectroscopy. Sediments were also measured for organic carbon (OC) by …

The Effect Of Vegetated Roofs On Acid Precipitation Runoff, Jennifer Gillen

Geology Theses and Dissertations

Vegetated, or “green” roofs are used in urban architecture and sustainable building to capture stormwater and enhance urban wildlife. Most research to date has focused on their water retention capabilities, but green roofs also have the potential to treat anthropogenic acid precipitation in urban environments. More specifically, green roofs could reduce sulfate, nitrate and hydrogen ion concentrations in runoff. One previous study has demonstrated that nitrate was reduced in water draining from a green roof (Berndtsson, et al. 2006), but this unpublished thesis appears to be the first comprehensive study of the effects of vegetated roof materials on major ions …

Trends In Streamflow Characteristics Of Selected Sites In The Elkhorn River, Salt Creek, And Lower Platte River Basins, Eastern Nebraska, 1928–2004, And Evaluation Of Streamflows In Relation To Instream-Flow Criteria, 1953–2004, Benjamin J. Dietsch, Julie A. Godberson, Gregory V. Steele

United States Geological Survey: Publications

The Nebraska Department of Natural Resources approved instream-flow appropriations on the Platte River to maintain fish communities, whooping crane roost habitat, and wet meadows used by several wild bird species. In the lower Platte River region, the Nebraska Game and Parks Commission owns an appropriation filed to maintain streamflow for fish communities between the Platte River confluence with the Elkhorn River and the mouth of the Platte River. Because Elkhorn River flow is an integral part of the flow in the reach addressed by this appropriation, the Upper Elkhorn and Lower Elkhorn Natural Resources Districts are involved in overall management …

Geomorphic Segmentation, Hydraulic Geometry, And Hydraulic Microhabitats Of The Niobrara River, Nebraska—Methods And Initial Results, Jason S. Alexander, Ronald B. Zelt, Nathaniel J. Schaepe

United States Geological Survey: Publications

The Niobrara River of Nebraska is a geologically, ecologically, and economically significant resource. The State of Nebraska has recognized the need to better manage the surface- and ground-water resources of the Niobrara River so they are sustainable in the long term. In cooperation with the Nebraska Game and Parks Commission, the U.S. Geological Survey is investigating the hydrogeomorphic settings and hydraulic geometry of the Niobrara River to assist in characterizing the types of broad-scale physical habitat attributes that may be of importance to the ecological resources of the river system. This report includes an inventory of surface-water and ground-water hydrology …

White-Nose Syndrome Threatens The Survival Of Hibernating Bats In North America, U.S. Geological Survey

United States Geological Survey: Publications

During the winter of 2006/2007, an affliction of unknown origin dubbed “White-Nose Syndrome” (WNS) began devastating colonies of hibernating bats in a small area around Albany, New York. Colonies of hibernating bats were reduced 81-97% at the affected caves and mines that were surveyed. Since then, White-Nose Syndrome has been detected more than 700 kilometers (450 mi) away from the original site, and has infected bats in eight surrounding states. Most species of bats that hibernate in the region are now known to be affected and little brown bats (Myotis lucifugus), northern long-eared bats (M. septentrionalis), …

Mercury, Methylmercury, And Other Constituents In Sediment And Water From Seasonal And Permanent Wetlands In The Cache Creek Settling Basin And Yolo Bypass, Yolo County, California, 2005−06, Mark Marvin-Dipasquale, Charles N. Alpers, Jacob A. Fleck

United States Geological Survey: Publications

This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three locations within the Cache Creek drainage basin; two within the Cache Creek Nature Preserve (CCNP) and one in the Cache Creek Settling Basin (CCSB) within the creek’s main channel near the southeast outlet to the Yolo Bypass. Two additional downstream sites within the …

Hydrodynamic Simulations Of Physical Aquatic Habitat Availability For Pallid Sturgeon In The Lower Missouri River, At Yankton, South Dakota, Kenslers Bend, Nebraska, Little Sioux, Iowa, And Miami, Missouri, 2006–07, Robert B. Jacobson, Harold E. Johnson Iii, Benjamin J. Dietsch

United States Geological Survey: Publications

The objective of this study was to assess the sensitivity of habitat availability in the Lower Missouri River to discharge variation, with emphasis on habitats that might support spawning of the endangered pallid sturgeon. We constructed computational hydrodynamic models for four reaches that were selected because of evidence that sturgeon have spawned in them. The reaches are located at Miami, Missouri (river mile 259.6–263.5), Little Sioux, Iowa (river mile 669.6–673.5), Kenslers Bend, Nebraska (river mile 743.9–748.1), and Yankton, South Dakota reach (river mile 804.8–808.4). The models were calibrated for a range of measured flow conditions, and run for a range …

Toxicity Of Polybrominated Diphenyl Ethers (De-71) In Chicken (Gallus Gallus), Mallard (Anas Platyrhynchos), And American Kestrel (Falco Sparverius) Embryos And Hatchlings, Moira A. Mckernan, Barnett A. Rattner, Robert C. Hales, Mary Ann Ottinger

United States Geological Survey: Staff Publications

Embryonic survival, pipping and hatching success, and sublethal biochemical, endocrine, and histological endpoints were examined in hatchling chickens (Gallus gallus), mallards (Anas platyrhynchos), and American kestrels (Falco sparverius) following air cell administration of a pentabrominated diphenyl ether (penta-BDE; DE-71) mixture (0.01–20 µg/g egg) or polychlorinated biphenyl (PCB) congener 126 (3,3’,4,4’,5-pentachlorobiphenyl; 0.002 µg/g egg). The penta-BDE decreased pipping and hatching success at concentrations of 10 and 20 µg/g egg in kestrels but had no effect on survival endpoints in chickens or mallards. Sublethal effects in hatchling chickens included ethoxyresorufin-O-dealkylase (EROD) induction and histological …

Investigating The Impact Of Microbial Interactions With Geologic Media On Geophysical Properties, Caroline A. Davis

Doctoral Dissertations

"The goals of this study were to investigate the effect of: (1) microbial metabolic byproducts, microbial growth, and biofilm formation on the low frequency electrical properties of porous media, (2) biofilm formation on acoustic wave properties, and (3) the natural electrical (self-potential) signatures associated with an in-situ biological permeable reactive barrier (PRB). The results suggest: (1) increases in electrolytic conductivity are consistent with increased concentrations of organic acids and biosurfactants; (2) mineral weathering promoted by organic acids causes increases in electrolytic conductivity, concomitant with increases in major cation concentrations; (3) interfacial conductivity generally parallels microbial cell concentrations and biofilm formation; …

Unusual Anatomy Of The Ectoparasitic Muricid Vitularia Salebrosa (King And Broderip, 1832) (Neogastropoda: Muricidae) From The Pacific Coast Of Panama, Luiz R. L. Simone, Gregory S. Herbert, Didier Merle

School of Geosciences Faculty and Staff Publications

The morphology and anatomy of Vitularia salebrosa, a muricid ectoparasitic on other mollusks, are investigated based on study of specimens from western Panama. Distinctive characters of this species include the small size of the buccal mass and radular apparatus, simplification of the odontophore muscles and diminished lateral teeth of the radula; an elongated, narrow proboscis; narrow digestive tract and a differentiable glandular region at the beginning of the posterior esophagus. These traits are consistent with adaptive specialization for an ectoparasitic life history

Extremely Slow Feeding In A Tropical Drilling Ectoparasite, Vitularia Salebrosa (King And Broderip, 1832) (Gastropoda: Muricidae), On Molluscan Hosts From Pacific Panama, Gregory S. Herbert, Gregory P. Dietl, Helena Fortunato, Luiz R. L. Simone, Jennifer Leigh Sliko

School of Geosciences Faculty and Staff Publications

This study documents one of the slowest feeding behaviors ever recorded for a muricid gastropod in one of the most biotically rigorous regions on the planet. In Pacific Panama, Vitularia salebrosa attacks mollusks by drilling through their shells. The duration of attacks estimated by isotope sclerochronology of oyster shells collected during attacks in progress ranges from 90 to 230 days, while experimental observation of interactions documented one attack greater than 103 days. The prolonged nature of attacks suggests that V. salebrosa is best characterized as an ectoparasite than as a predator, which is the ancestral condition in the Muricidae. An …

Pdi, Reactive Oxygen Species Stress And Polyphenolic Phytochemicals: Implications For Neurodegenerative Diseases, Rituraj Pal

Open Access Theses & Dissertations

PDI, protein disulfide isomerase, is one of the most versatile proteins and highly expressed in mammalian cells because there is a vast number of proteins that must undergo processing before secretion to their final destinations. PDI has several functions: oxidation of nascent proteins and isomerization of existing disulfide bonds. It also possesses chaperone activity and participates in protein degradation. Because of its structure, PDI can exist in a reduced or oxidized form. In mammalian cells it is mostly reduced due to the high demand of disulfide bond shuffling of secreted proteins within the ER, PDI a, a', and b' posses …