Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains of New York, USA, which have similar topographic and hydrologic characteristics but contrasting stream nitrate ($\\hbox{NO}_{3}^{-}$) concentrations. We characterized the mechanisms by which $\\hbox{NO}_{3}^{-}$ reaches the streams during hydrological events in these catchments, aiming to reconcile our field data with our conceptual model of factors that regulate nutrient exports from forested catchments. Combined hydrometric, chemical and isotopic (δ$\\hbox{NO}_{3}^{-}$) data showed that the relative contributions of both soil and ground water sources were similar between the two catchments. Temporal patterns of stream chemistry were markedly different between S14 and S15, however, because the water sources in the two catchments have different solute concentrations. During late summer/fall, the largest source of $\\hbox{NO}_{3}^{-}$ in S14 was till groundwater, whereas shallow soil was the largest $\\hbox{NO}_{3}^{-}$ source in S15. $\\hbox{NO}_{3}^{-}$ concentrations in surface water decreased in S14, whereas they increased in S15 because an increasing proportion of stream flow was derived from shallow soil sources. During snowmelt, the largest sources of $\\hbox{NO}_{3}^{-}$were in the near‐surface soil in both catchments. Concentrations of $\\hbox{NO}_{3}^{-}$ increased as stream discharge increased and usually peaked before peak discharge, when shallow soil water sources made the largest contribution to stream discharge. The timing of peaks in stream $\\hbox{NO}_{3}^{-}$concentrations was affected by antecedent moisture conditions. By elucidating the factors that affect sources and transport of N, including differences in the soil nutrient cycling and hydrological characteristics of S14 and S15, this study contributes to the overall conceptualization of $\\hbox{NO}_{3}^{-}$ release from temperate forested catchments.
Anthropogenic features such as urbanization, roads, and power lines, are increasing in western United States landscapes in response to rapidly growing human populations. However, their spatial effects have not been evaluated. Our goal was to model the human footprint across the western United States. We first delineated the actual area occupied by anthropogenic features, the physical effect area. Next, we developed the human footprint model based on the ecological effect area, the zone influenced by features beyond their physical presence, by combining seven input models: three models quantified top-down anthropogenic influences of synanthropic predators (avian predators, domestic dog and cat presence risk), and four models quantified bottom-up anthropogenic influences on habitat (invasion of exotic plants, human-caused fires, energy extraction, and anthropogenic wildland fragmentation). Using independent bird population data, we found bird abundance of four synanthropic species to correlate positively with human footprint intensity and negatively for three of the six species influenced by habitat fragmentation. We then evaluated the extent of the human footprint in relation to terrestrial (ecoregions) and aquatic systems (major rivers and lakes), regional management and conservation status, physical environment, and temporal changes in human actions. The physical effect area of anthropogenic features covered 13% of the western United States with agricultural land (9.8%) being most dominant. High-intensity human footprint areas (class 8–10) overlapped highly productive low-elevation private landholdings and covered 7% of the western United States compared to 48% for low-intensity areas (class 1–3), which were confined to low-productivity high-elevation federal landholdings. Areas within 1 km of rivers were more affected by the human footprint compared to lakes. Percentage human population growth was higher in low-intensity human footprint areas. The disproportional regional effects of the human footprint on landscapes in the western United States create a challenge to management of ecosystems and wildlife populations. Using footprint models, managers can plan land use actions, develop restoration scenarios, and identify areas of high conservation value at local landscapes within a regional context. Moreover, human footprint models serve as a tool to stratify landscapes for studies investigating floral and faunal response to human disturbance intensity gradients.
","language":"English","publisher":"ESA","doi":"10.1890/07-0480.1","usgsCitation":"Leu, M., Hanser, S., and Knick, S., 2008, The human footprint in the west: a large-scale analysis of anthropogenic impacts.: Ecological Applications, v. 18, no. 5, p. 1119-1139, https://doi.org/10.1890/07-0480.1.","productDescription":"21 p.","startPage":"1119","endPage":"1139","costCenters":[{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"links":[{"id":438856,"rank":1,"type":{"id":30,"text":"Data Release"},"url":"https://doi.org/10.5066/P9BMGEMJ","text":"USGS data release","linkHelpText":"Agricultural Land in the Western United States"},{"id":242118,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bacc1e4b08c986b323700","contributors":{"authors":[{"text":"Leu, M.","contributorId":90942,"corporation":false,"usgs":true,"family":"Leu","given":"M.","email":"","affiliations":[],"preferred":false,"id":441391,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hanser, S.E.","contributorId":13823,"corporation":false,"usgs":true,"family":"Hanser","given":"S.E.","email":"","affiliations":[],"preferred":false,"id":441389,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Knick, S.T.","contributorId":71290,"corporation":false,"usgs":true,"family":"Knick","given":"S.T.","email":"","affiliations":[],"preferred":false,"id":441390,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70030352,"text":"70030352 - 2008 - Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates","interactions":[],"lastModifiedDate":"2019-12-04T06:32:07","indexId":"70030352","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2682,"text":"Marine and Petroleum Geology","active":true,"publicationSubtype":{"id":10}},"title":"Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates","docAbstract":"Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on sediments recovered during drilling in the northern Gulf of Mexico at the Atwater Valley and Keathley Canyon sites as part of the 2005 Chevron Joint Industry Project on Methane Hydrates. The tested specimens include both unremolded specimens (as recovered from the original core liner) and remolded sediments both without gas hydrate and with pore fluid exchanged to attain 100% synthetic (tetrahydrofuran) hydrate saturation at any stage of loading. Test results demonstrate the extent to which the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. We also show how permittivity and electrical conductivity data can be used to estimate the evolution of hydrate volume fraction during formation. The gradual evolution of geophysical properties during hydrate formation probably reflects the slow increase in ionic concentration in the pore fluid due to ion exclusion in closed systems and the gradual decrease in average pore size in which the hydrate forms. During hydrate formation, the increase in S-wave velocity is delayed with respect to the decrease in permittivity, consistent with hydrate formation on mineral surfaces and subsequent crystal growth toward the pore space. No significant decementation/debonding occurred in 100% THF hydrate-saturated sediments during unloading, hence the probability of sampling hydrate-bearing sediments without disturbing the original sediment fabric is greatest for samples in which the gas hydrate is primarily responsible for maintaining the sediment fabric and for which the time between core retrieval and restoration of in situ effective stress in the laboratory is minimized. In evaluating the impact of core retrieval on specimen properties, it is also important to consider how far removed hydrate-bearing samples are from hydrate stability conditions.
","language":"English","publisher":"Elsevier","doi":"10.1016/j.marpetgeo.2008.01.019","issn":"02648","usgsCitation":"Lee, J., Santamarina, J., and Ruppel, C., 2008, Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates: Marine and Petroleum Geology, v. 25, no. 9, p. 884-895, https://doi.org/10.1016/j.marpetgeo.2008.01.019.","productDescription":"12 p.","startPage":"884","endPage":"895","costCenters":[{"id":678,"text":"Woods Hole Coastal and Marine Science Center","active":true,"usgs":true}],"links":[{"id":239301,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Louisiana, Texas","otherGeospatial":"Gulf of Mexico","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -89.8681640625,\n 30.29701788337205\n ],\n [\n -93.251953125,\n 30.372875188118016\n ],\n [\n -95.361328125,\n 29.84064389983441\n ],\n [\n -97.8662109375,\n 28.613459424004414\n ],\n [\n -97.822265625,\n 26.588527147308614\n ],\n [\n -97.294921875,\n 25.799891182088334\n ],\n [\n -95.712890625,\n 25.443274612305746\n ],\n [\n -91.845703125,\n 27.21555620902969\n ],\n [\n -88.76953125,\n 29.075375179558346\n ],\n [\n -89.8681640625,\n 30.29701788337205\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"25","issue":"9","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a5358e4b0c8380cd6ca00","contributors":{"authors":[{"text":"Lee, J.Y.","contributorId":20061,"corporation":false,"usgs":true,"family":"Lee","given":"J.Y.","email":"","affiliations":[],"preferred":false,"id":426809,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Santamarina, J.C.","contributorId":50283,"corporation":false,"usgs":true,"family":"Santamarina","given":"J.C.","email":"","affiliations":[],"preferred":false,"id":426810,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Ruppel, C.","contributorId":82050,"corporation":false,"usgs":true,"family":"Ruppel","given":"C.","email":"","affiliations":[],"preferred":false,"id":426811,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033548,"text":"70033548 - 2008 - Evaluating sampling designs by computer simulation: A case study with the Missouri bladderpod","interactions":[],"lastModifiedDate":"2012-03-12T17:21:32","indexId":"70033548","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3103,"text":"Population Ecology","active":true,"publicationSubtype":{"id":10}},"title":"Evaluating sampling designs by computer simulation: A case study with the Missouri bladderpod","docAbstract":"To effectively manage rare populations, accurate monitoring data are critical. Yet many monitoring programs are initiated without careful consideration of whether chosen sampling designs will provide accurate estimates of population parameters. Obtaining accurate estimates is especially difficult when natural variability is high, or limited budgets determine that only a small fraction of the population can be sampled. The Missouri bladderpod, Lesquerella filiformis Rollins, is a federally threatened winter annual that has an aggregated distribution pattern and exhibits dramatic interannual population fluctuations. Using the simulation program SAMPLE, we evaluated five candidate sampling designs appropriate for rare populations, based on 4 years of field data: (1) simple random sampling, (2) adaptive simple random sampling, (3) grid-based systematic sampling, (4) adaptive grid-based systematic sampling, and (5) GIS-based adaptive sampling. We compared the designs based on the precision of density estimates for fixed sample size, cost, and distance traveled. Sampling fraction and cost were the most important factors determining precision of density estimates, and relative design performance changed across the range of sampling fractions. Adaptive designs did not provide uniformly more precise estimates than conventional designs, in part because the spatial distribution of L. filiformis was relatively widespread within the study site. Adaptive designs tended to perform better as sampling fraction increased and when sampling costs, particularly distance traveled, were taken into account. The rate that units occupied by L. filiformis were encountered was higher for adaptive than for conventional designs. Overall, grid-based systematic designs were more efficient and practically implemented than the others. ?? 2008 The Society of Population Ecology and Springer.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Population Ecology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s10144-008-0100-x","issn":"14383","usgsCitation":"Morrison, L., Smith, D., Young, C., and Nichols, D., 2008, Evaluating sampling designs by computer simulation: A case study with the Missouri bladderpod: Population Ecology, v. 50, no. 4, p. 417-425, https://doi.org/10.1007/s10144-008-0100-x.","startPage":"417","endPage":"425","numberOfPages":"9","costCenters":[],"links":[{"id":214429,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s10144-008-0100-x"},{"id":242153,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"50","issue":"4","noUsgsAuthors":false,"publicationDate":"2008-07-23","publicationStatus":"PW","scienceBaseUri":"505a0bf2e4b0c8380cd52964","contributors":{"authors":[{"text":"Morrison, L.W.","contributorId":39482,"corporation":false,"usgs":true,"family":"Morrison","given":"L.W.","email":"","affiliations":[],"preferred":false,"id":441392,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Smith, D. R. 0000-0001-6074-9257","orcid":"https://orcid.org/0000-0001-6074-9257","contributorId":44108,"corporation":false,"usgs":true,"family":"Smith","given":"D. R.","affiliations":[{"id":365,"text":"Leetown Science Center","active":true,"usgs":true}],"preferred":false,"id":441393,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Young, C.","contributorId":67709,"corporation":false,"usgs":true,"family":"Young","given":"C.","email":"","affiliations":[],"preferred":false,"id":441394,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Nichols, D.W.","contributorId":107115,"corporation":false,"usgs":true,"family":"Nichols","given":"D.W.","email":"","affiliations":[],"preferred":false,"id":441395,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033550,"text":"70033550 - 2008 - Observations of the north polar water ice annulus on Mars using THEMIS and TES","interactions":[],"lastModifiedDate":"2019-02-19T09:34:12","indexId":"70033550","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3083,"text":"Planetary and Space Science","active":true,"publicationSubtype":{"id":10}},"title":"Observations of the north polar water ice annulus on Mars using THEMIS and TES","docAbstract":"The Martian seasonal CO2 ice caps advance and retreat each year. In the spring, as the CO2 cap gradually retreats, it leaves behind an extensive defrosting zone from the solid CO2 cap to the location where all CO2 frost has sublimated. We have been studying this phenomenon in the north polar region using data from the THermal EMission Imaging System (THEMIS), a visible and infra-red (IR) camera on the Mars Odyssey spacecraft, and the Thermal Emission Spectrometer (TES) on Mars Global Surveyor. Recently, we discovered that some THEMIS images of the CO2 defrosting zone contain evidence for a distinct defrosting phenomenon: some areas just south of the CO2 cap edge are too bright in visible wavelengths to be defrosted terrain, but too warm in the IR to be CO2 ice. We hypothesize that we are seeing evidence for a seasonal annulus of water ice (frost) that recedes with the seasonal CO2 cap, as predicted by previous workers. In this paper, we describe our observations with THEMIS and compare them to simultaneous observations by TES and OMEGA. All three instruments find that this phenomenon is distinct from the CO2 cap and most likely composed of water ice. We also find strong evidence that the annulus widens as it recedes. Finally, we show that this annulus can be detected in the raw THEMIS data as it is collected, enabling future long-term onboard monitoring.
","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Planetary and Space Science","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Elsevier","doi":"10.1016/j.pss.2007.08.008","issn":"00320633","usgsCitation":"Wagstaff, K.L., Titus, T.N., Ivanov, A.B., Castano, R., and Bandfield, J.L., 2008, Observations of the north polar water ice annulus on Mars using THEMIS and TES: Planetary and Space Science, v. 56, no. 2, p. 256-265, https://doi.org/10.1016/j.pss.2007.08.008.","productDescription":"10 p.","startPage":"256","endPage":"265","numberOfPages":"10","costCenters":[{"id":131,"text":"Astrogeology Science Center","active":true,"usgs":true}],"links":[{"id":242186,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"otherGeospatial":"Mars","volume":"56","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a6ac3e4b0c8380cd74338","contributors":{"authors":[{"text":"Wagstaff, Kiri L.","contributorId":213351,"corporation":false,"usgs":false,"family":"Wagstaff","given":"Kiri","email":"","middleInitial":"L.","affiliations":[{"id":7023,"text":"Jet Propulsion Laboratory, California Institute of Technology","active":true,"usgs":false}],"preferred":false,"id":441400,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Titus, Timothy N. 0000-0003-0700-4875 ttitus@usgs.gov","orcid":"https://orcid.org/0000-0003-0700-4875","contributorId":146,"corporation":false,"usgs":true,"family":"Titus","given":"Timothy","email":"ttitus@usgs.gov","middleInitial":"N.","affiliations":[{"id":131,"text":"Astrogeology Science Center","active":true,"usgs":true}],"preferred":true,"id":441404,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Ivanov, Anton B.","contributorId":213352,"corporation":false,"usgs":false,"family":"Ivanov","given":"Anton","email":"","middleInitial":"B.","affiliations":[{"id":7023,"text":"Jet Propulsion Laboratory, California Institute of Technology","active":true,"usgs":false}],"preferred":false,"id":441403,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Castano, Rebecca","contributorId":213353,"corporation":false,"usgs":false,"family":"Castano","given":"Rebecca","email":"","affiliations":[{"id":7023,"text":"Jet Propulsion Laboratory, California Institute of Technology","active":true,"usgs":false}],"preferred":false,"id":441402,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Bandfield, Joshua L.","contributorId":140356,"corporation":false,"usgs":false,"family":"Bandfield","given":"Joshua","email":"","middleInitial":"L.","affiliations":[{"id":13469,"text":"Space Science Institute, Boulder, Colorado, USA","active":true,"usgs":false}],"preferred":false,"id":441401,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70030513,"text":"70030513 - 2008 - Soil sail content estimation in the Yellow River delta with satellite hyperspectral data","interactions":[],"lastModifiedDate":"2020-09-10T16:50:41.322664","indexId":"70030513","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1175,"text":"Canadian Journal of Remote Sensing","active":true,"publicationSubtype":{"id":10}},"title":"Soil sail content estimation in the Yellow River delta with satellite hyperspectral data","docAbstract":"Soil salinization is one of the most common land degradation processes and is a severe environmental hazard. The primary objective of this study is to investigate the potential of predicting salt content in soils with hyperspectral data acquired with EO-1 Hyperion. Both partial least-squares regression (PLSR) and conventional multiple linear regression (MLR), such as stepwise regression (SWR), were tested as the prediction model. PLSR is commonly used to overcome the problem caused by high-dimensional and correlated predictors. Chemical analysis of 95 samples collected from the top layer of soils in the Yellow River delta area shows that salt content was high on average, and the dominant chemicals in the saline soil were NaCl and MgCl2. Multivariate models were established between soil contents and hyperspectral data. Our results indicate that the PLSR technique with laboratory spectral data has a strong prediction capacity. Spectral bands at 1487–1527, 1971–1991, 2032–2092, and 2163–2355 nm possessed large absolute values of regression coefficients, with the largest coefficient at 2203 nm. We obtained a root mean squared error (RMSE) for calibration (with 61 samples) of RMSEC = 0.753 (R2 = 0.893) and a root mean squared error for validation (with 30 samples) of RMSEV = 0.574. The prediction model was applied on a pixel-by-pixel basis to a Hyperion reflectance image to yield a quantitative surface distribution map of soil salt content. The result was validated successfully from 38 sampling points. We obtained an RMSE estimate of 1.037 (R2 = 0.784) for the soil salt content map derived by the PLSR model. The salinity map derived from the SWR model shows that the predicted value is higher than the true value. These results demonstrate that the PLSR method is a more suitable technique than stepwise regression for quantitative estimation of soil salt content in a large area.
","language":"English","publisher":"Taylor & Francis","usgsCitation":"Weng, Y., Gong, P., and Zhu, Z., 2008, Soil sail content estimation in the Yellow River delta with satellite hyperspectral data: Canadian Journal of Remote Sensing, v. 34, no. 3, p. 259-270.","productDescription":"12 p.","startPage":"259","endPage":"270","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":222,"text":"Earth Resources Observation and Science (EROS) Center","active":true,"usgs":true}],"links":[{"id":239105,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":378314,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://www.tandfonline.com/doi/abs/10.5589/m08-017"}],"volume":"34","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9218e4b08c986b319ccd","contributors":{"authors":[{"text":"Weng, Yongling","contributorId":64767,"corporation":false,"usgs":true,"family":"Weng","given":"Yongling","email":"","affiliations":[],"preferred":false,"id":427436,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gong, Peng","contributorId":102393,"corporation":false,"usgs":true,"family":"Gong","given":"Peng","affiliations":[],"preferred":false,"id":427435,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Zhu, Zhi-Liang zzhu@usgs.gov","contributorId":3636,"corporation":false,"usgs":true,"family":"Zhu","given":"Zhi-Liang","email":"zzhu@usgs.gov","affiliations":[{"id":223,"text":"Earth Resources Observation and Science (EROS) Center (Geography)","active":false,"usgs":true}],"preferred":false,"id":427434,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033564,"text":"70033564 - 2008 - Structural equation modeling for observational studies","interactions":[],"lastModifiedDate":"2012-03-12T17:21:30","indexId":"70033564","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2508,"text":"Journal of Wildlife Management","active":true,"publicationSubtype":{"id":10}},"title":"Structural equation modeling for observational studies","docAbstract":"Structural equation modeling (SEM) represents a framework for developing and evaluating complex hypotheses about systems. This method of data analysis differs from conventional univariate and multivariate approaches familiar to most biologists in several ways. First, SEMs are multiequational and capable of representing a wide array of complex hypotheses about how system components interrelate. Second, models are typically developed based on theoretical knowledge and designed to represent competing hypotheses about the processes responsible for data structure. Third, SEM is conceptually based on the analysis of covariance relations. Most commonly, solutions are obtained using maximum-likelihood solution procedures, although a variety of solution procedures are used, including Bayesian estimation. Numerous extensions give SEM a very high degree of flexibility in dealing with nonnormal data, categorical responses, latent variables, hierarchical structure, multigroup comparisons, nonlinearities, and other complicating factors. Structural equation modeling allows researchers to address a variety of questions about systems, such as how different processes work in concert, how the influences of perturbations cascade through systems, and about the relative importance of different influences. I present 2 example applications of SEM, one involving interactions among lynx (Lynx pardinus), mongooses (Herpestes ichneumon), and rabbits (Oryctolagus cuniculus), and the second involving anuran species richness. Many wildlife ecologists may find SEM useful for understanding how populations function within their environments. Along with the capability of the methodology comes a need for care in the proper application of SEM.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Wildlife Management","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2193/2007-307","issn":"0022541X","usgsCitation":"Grace, J., 2008, Structural equation modeling for observational studies: Journal of Wildlife Management, v. 72, no. 1, p. 14-22, https://doi.org/10.2193/2007-307.","startPage":"14","endPage":"22","numberOfPages":"9","costCenters":[],"links":[{"id":214163,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2193/2007-307"},{"id":241857,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"72","issue":"1","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505b9be4e4b08c986b31d157","contributors":{"authors":[{"text":"Grace, J.B. 0000-0001-6374-4726","orcid":"https://orcid.org/0000-0001-6374-4726","contributorId":38938,"corporation":false,"usgs":true,"family":"Grace","given":"J.B.","affiliations":[],"preferred":false,"id":441454,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70032758,"text":"70032758 - 2008 - Multiyear riparian evapotranspiration and groundwater use for a semiarid watershed","interactions":[],"lastModifiedDate":"2012-03-12T17:21:24","indexId":"70032758","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2183,"text":"Journal of Arid Environments","active":true,"publicationSubtype":{"id":10}},"title":"Multiyear riparian evapotranspiration and groundwater use for a semiarid watershed","docAbstract":"Riparian evapotranspiration (ET) is a major component of the surface and subsurface water balance for many semiarid watersheds. Measurement or model-based estimates of ET are often made on a local scale, but spatially distributed estimates are needed to determine ET over catchments. In this paper, we document the ET that was quantified over 3 years using eddy covariance for three riparian ecosystems along the Upper San Pedro River of southeastern Arizona, USA, and we use a water balance equation to determine annual groundwater use. Riparian evapotranspiration and groundwater use for the watershed were then determined by using a calibrated, empirical model that uses 16-day, 250-1000 m remote-sensing products for the years of 2001-2005. The inputs for the model were derived entirely from the NASA MODIS sensor and consisted of the Enhanced Vegetation Index and land surface temperature. The scaling model was validated using subsets of the entire dataset (omitting different sites or years) and its capable performance for well-watered sites (MAD=0.32 mm day-1, R2=0.93) gave us confidence in using it to determine ET over the watershed. Three years of eddy covariance data for the riparian sites reveal that ET and groundwater use increased as woody plant density increased. Groundwater use was less variable at the woodland site, which had the greatest density of phreatophytes. Annual riparian groundwater use within the watershed was nearly constant over the study period despite an on-going drought. For the San Pedro alone, the amounts determined in this paper are within the range of most recently reported values that were derived using an entirely different approach. However, because of our larger estimates for groundwater use for the main tributary of the San Pedro, the watershed totals were higher. The approach presented here can provide riparian ET and groundwater use amounts that reflect real natural variability in phreatophyte withdrawals and improve the accuracy of a watershed's water budget. ?? 2008 Elsevier Ltd. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Arid Environments","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.jaridenv.2008.01.001","issn":"01401963","usgsCitation":"Scott, R., Cable, W., Huxman, T., Nagler, P., Hernandez, M., and Goodrich, D., 2008, Multiyear riparian evapotranspiration and groundwater use for a semiarid watershed: Journal of Arid Environments, v. 72, no. 7, p. 1232-1246, https://doi.org/10.1016/j.jaridenv.2008.01.001.","startPage":"1232","endPage":"1246","numberOfPages":"15","costCenters":[],"links":[{"id":241427,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":213770,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.jaridenv.2008.01.001"}],"volume":"72","issue":"7","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a60bfe4b0c8380cd7165c","contributors":{"authors":[{"text":"Scott, R.L.","contributorId":103865,"corporation":false,"usgs":true,"family":"Scott","given":"R.L.","email":"","affiliations":[],"preferred":false,"id":437786,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cable, W.L.","contributorId":24578,"corporation":false,"usgs":true,"family":"Cable","given":"W.L.","email":"","affiliations":[],"preferred":false,"id":437782,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Huxman, T. E.","contributorId":33825,"corporation":false,"usgs":false,"family":"Huxman","given":"T. E.","affiliations":[{"id":7042,"text":"University of Arizona","active":true,"usgs":false}],"preferred":false,"id":437784,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Nagler, P.L. 0000-0003-0674-103X","orcid":"https://orcid.org/0000-0003-0674-103X","contributorId":29937,"corporation":false,"usgs":true,"family":"Nagler","given":"P.L.","affiliations":[],"preferred":false,"id":437783,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Hernandez, M.","contributorId":10234,"corporation":false,"usgs":true,"family":"Hernandez","given":"M.","affiliations":[],"preferred":false,"id":437781,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Goodrich, D.C.","contributorId":98492,"corporation":false,"usgs":false,"family":"Goodrich","given":"D.C.","email":"","affiliations":[],"preferred":false,"id":437785,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70033004,"text":"70033004 - 2008 - Assigning king eiders to wintering regions in the Bering Sea using stable isotopes of feathers and claws","interactions":[],"lastModifiedDate":"2012-03-12T17:21:37","indexId":"70033004","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2663,"text":"Marine Ecology Progress Series","active":true,"publicationSubtype":{"id":10}},"title":"Assigning king eiders to wintering regions in the Bering Sea using stable isotopes of feathers and claws","docAbstract":"Identification of wintering regions for birds sampled during the breeding season is crucial to understanding how events outside the breeding season may affect populations. We assigned king eiders captured on breeding grounds in northern Alaska to 3 broad geographic wintering regions in the Bering Sea using stable carbon and nitrogen isotopes obtained from head feathers. Using a discriminant function analysis of feathers obtained from birds tracked with satellite transmitters, we estimated that 88 % of feathers were assigned to the region in which they were grown. We then assigned 84 birds of unknown origin to wintering regions based on their head feather isotope ratios, and tested the utility of claws for geographic assignment. Based on the feather results, we estimated that similar proportions of birds in our study area use each of the 3 wintering regions in the Bering Sea. These results are in close agreement with estimates from satellite telemetry and show the usefulness of stable isotope signatures of feathers in assigning marine birds to geographic regions. The use of claws is currently limited by incomplete understanding of claw growth rates. Data presented here will allow managers of eiders, other marine birds, and marine mammals to assign animals to regions in the Bering Sea based on stable isotope signatures of body tissues. ?? Inter-Research 2008.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Marine Ecology Progress Series","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.3354/meps07744","issn":"01718","usgsCitation":"Oppel, S., and Powell, A., 2008, Assigning king eiders to wintering regions in the Bering Sea using stable isotopes of feathers and claws: Marine Ecology Progress Series, v. 373, p. 149-156, https://doi.org/10.3354/meps07744.","startPage":"149","endPage":"156","numberOfPages":"8","costCenters":[],"links":[{"id":488078,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.3354/meps07744","text":"Publisher Index Page"},{"id":241079,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":213453,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3354/meps07744"}],"volume":"373","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ee8ae4b0c8380cd49de7","contributors":{"authors":[{"text":"Oppel, S.","contributorId":44001,"corporation":false,"usgs":true,"family":"Oppel","given":"S.","affiliations":[],"preferred":false,"id":438926,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Powell, A.N.","contributorId":66194,"corporation":false,"usgs":true,"family":"Powell","given":"A.N.","email":"","affiliations":[],"preferred":false,"id":438927,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70033565,"text":"70033565 - 2008 - A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA","interactions":[],"lastModifiedDate":"2020-07-30T14:41:50.434855","indexId":"70033565","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1109,"text":"Bulletin of Volcanology","active":true,"publicationSubtype":{"id":10}},"title":"A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA","docAbstract":"We mapped the geometry of 13 silicic dikes at Summer Coon, an eroded Oligocene stratovolcano in southern Colorado, to investigate various characteristics of radial dike emplacement in composite volcanoes. Exposed dikes are up to about 7 km in length and have numerous offset segments along their upper peripheries. Surprisingly, most dikes at Summer Coon increase in thickness with distance from the center of the volcano. Magma pressure in a dike is expected to lessen away from the pressurized source region, which would encourage a blade-like dike to decrease in thickness with distance from the center of the volcano. We attribute the observed thickness pattern as evidence of a driving pressure gradient, which is caused by decreasing host rock shear modulus and horizontal stress, both due to decreasing emplacement depths beneath the sloping flanks of the volcano. Based on data from Summer Coon, we propose that radial dikes originate at depth below the summit of a host volcano and follow steeply inclined paths towards the surface. Near the interface between volcanic cone and basement, which may represent a neutral buoyancy surface or stress barrier, magma is transported subhorizontally and radially away from the center of the volcano in blade-like dikes. The dikes thicken with increasing radial distance, and offset segments and fingers form along the upper peripheries of the intrusions. Eruptions may occur anywhere along the length of the dikes, but the erupted volume will generally be greater for dike-fed eruptions far from the center of the host volcano owing to the increase in driving pressure with distance from the source. Observed eruptive volumes, vent locations, and vent-area intrusions from inferred post-glacial dike-fed eruptions at Mount Adams, Washington, USA, support the proposed model. Hazards associated with radial dike emplacement are therefore greater for longer dikes that propagate to the outer flanks of a volcano.
","language":"English","publisher":"Springer","doi":"10.1007/s00445-007-0175-9","issn":"02588900","usgsCitation":"Poland, M.P., Moats, W., and Fink, J., 2008, A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA: Bulletin of Volcanology, v. 70, no. 7, p. 861-875, https://doi.org/10.1007/s00445-007-0175-9.","productDescription":"15 p.","startPage":"861","endPage":"875","numberOfPages":"15","costCenters":[{"id":336,"text":"Hawaiian Volcano Observatory","active":false,"usgs":true},{"id":616,"text":"Volcano Hazards Team","active":false,"usgs":true}],"links":[{"id":241858,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Colorado","otherGeospatial":"Summer Coon volcano","geographicExtents":"{\n\n\"type\": \"FeatureCollection\",\n\n\"features\": [\n\n{\n\n\"type\": \"Feature\",\n\n\"properties\": {},\n\n\"geometry\": {\n\n\"type\": \"Polygon\",\n\n\"coordinates\": [\n\n[\n\n[\n\n-106.3916015625,\n\n37.693601037244406\n\n],\n\n[\n\n-106.10733032226562,\n\n37.693601037244406\n\n],\n\n[\n\n-106.10733032226562,\n\n37.835818618104156\n\n],\n\n[\n\n-106.3916015625,\n\n37.835818618104156\n\n],\n\n[\n\n-106.3916015625,\n\n37.693601037244406\n\n]\n\n]\n\n]\n\n}\n\n}\n\n]\n\n}","volume":"70","issue":"7","noUsgsAuthors":false,"publicationDate":"2007-11-06","publicationStatus":"PW","scienceBaseUri":"5059e46be4b0c8380cd46655","contributors":{"authors":[{"text":"Poland, Michael P. 0000-0001-5240-6123 mpoland@usgs.gov","orcid":"https://orcid.org/0000-0001-5240-6123","contributorId":146118,"corporation":false,"usgs":true,"family":"Poland","given":"Michael","email":"mpoland@usgs.gov","middleInitial":"P.","affiliations":[{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"preferred":true,"id":441457,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moats, W.P.","contributorId":7923,"corporation":false,"usgs":true,"family":"Moats","given":"W.P.","email":"","affiliations":[],"preferred":false,"id":441455,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Fink, J.H.","contributorId":44367,"corporation":false,"usgs":true,"family":"Fink","given":"J.H.","email":"","affiliations":[],"preferred":false,"id":441456,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70032757,"text":"70032757 - 2008 - Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data","interactions":[],"lastModifiedDate":"2019-04-03T14:04:31","indexId":"70032757","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3254,"text":"Remote Sensing of Environment","printIssn":"0034-4257","active":true,"publicationSubtype":{"id":10}},"title":"Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data","docAbstract":"A remote sensing approach permits for the first time the derivation of a map of the carbon dioxide concentration in a volcanic plume. The airborne imaging remote sensing overcomes the typical difficulties associated with the ground measurements and permits rapid and large views of the volcanic processes together with the measurements of volatile components exolving from craters. Hyperspectral images in the infrared range (1900–2100 nm), where carbon dioxide absorption lines are present, have been used. These images were acquired during an airborne campaign by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over the Pu`u` O`o Vent situated at the Kilauea East Rift zone, Hawaii. Using a radiative transfer model to simulate the measured up-welling spectral radiance and by applying the newly developed mapping technique, the carbon dioxide concentration map of the Pu`u` O`o Vent plume were obtained. The carbon dioxide integrated flux rate were calculated and a mean value of 396 ± 138 t d− 1 was obtained. This result is in agreement, within the measurements errors, with those of the ground measurements taken during the airborne campaign. 2008 Elsevier Inc.
","language":"English","publisher":"Elsevier","doi":"10.1016/j.rse.2008.03.010","issn":"00344257","usgsCitation":"Spinetti, C., Carrere, V., Buongiorno, M.F., Sutton, A.J., and Elias, T., 2008, Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data: Remote Sensing of Environment, v. 112, no. 6, p. 3192-3199, https://doi.org/10.1016/j.rse.2008.03.010.","productDescription":"8 p.","startPage":"3192","endPage":"3199","costCenters":[{"id":615,"text":"Volcano Hazards Program","active":true,"usgs":true}],"links":[{"id":241426,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":213769,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.rse.2008.03.010"}],"volume":"112","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f361e4b0c8380cd4b775","contributors":{"authors":[{"text":"Spinetti, C.","contributorId":64899,"corporation":false,"usgs":true,"family":"Spinetti","given":"C.","affiliations":[],"preferred":false,"id":437778,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Carrere, V.","contributorId":31212,"corporation":false,"usgs":true,"family":"Carrere","given":"V.","affiliations":[],"preferred":false,"id":437777,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Buongiorno, M. Fabrizia","contributorId":102698,"corporation":false,"usgs":true,"family":"Buongiorno","given":"M.","email":"","middleInitial":"Fabrizia","affiliations":[],"preferred":false,"id":437780,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Sutton, A. J. 0000-0003-1902-3977","orcid":"https://orcid.org/0000-0003-1902-3977","contributorId":28983,"corporation":false,"usgs":true,"family":"Sutton","given":"A.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":437776,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Elias, T. 0000-0002-9592-4518","orcid":"https://orcid.org/0000-0002-9592-4518","contributorId":71195,"corporation":false,"usgs":true,"family":"Elias","given":"T.","affiliations":[],"preferred":false,"id":437779,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70033566,"text":"70033566 - 2008 - Water movement within the unsaturated zone in four agricultural areas of the United States","interactions":[],"lastModifiedDate":"2012-03-12T17:21:30","indexId":"70033566","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2262,"text":"Journal of Environmental Quality","active":true,"publicationSubtype":{"id":10}},"title":"Water movement within the unsaturated zone in four agricultural areas of the United States","docAbstract":"Millions of tons of agricultural fertilizer and pesticides are applied annually in the USA. Due to the potential for these chemicals to migrate to groundwater, a study was conducted in 2004 using field data to calculate water budgets, rates of groundwater recharge and times of water travel through the unsaturated zone and to identify factors that influence these phenomena. Precipitation was the only water input at sites in Indiana and Maryland; irrigation accounted for about 80% of total water input at sites in California and Washington. Recharge at the Indiana site (47.5 cm) and at the Maryland site (31.5 cm) were equivalent to 51 and 32%, respectively, of annual precipitation and occurred between growing seasons. Recharge at the California site (42.3 cm) and Washington site (11.9 cm) occurred in response to irrigation events and was about 29 and 13% of total water input, respectively. Average residence time of water in the unsaturated zone, calculated using a piston-flow approach, ranged from less than 1 yr at the Indiana site to more than 8 yr at the Washington site. Results of bromide tracer tests indicate that at three of the four sites, a fraction of the water applied at land surface may have traveled to the water table in less than 1 yr. The timing and intensity of precipitation and irrigation were the dominant factors controlling recharge, suggesting that the time of the year at which chemicals are applied may be important for chemical transport through the unsaturated zone. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Environmental Quality","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2134/jeq2006.0561","issn":"00472425","usgsCitation":"Fisher, L., and Healy, R.W., 2008, Water movement within the unsaturated zone in four agricultural areas of the United States: Journal of Environmental Quality, v. 37, no. 3, p. 1051-1063, https://doi.org/10.2134/jeq2006.0561.","startPage":"1051","endPage":"1063","numberOfPages":"13","costCenters":[],"links":[{"id":214195,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2134/jeq2006.0561"},{"id":241890,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"37","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bc85be4b08c986b32c8cf","contributors":{"authors":[{"text":"Fisher, L.H.","contributorId":34725,"corporation":false,"usgs":true,"family":"Fisher","given":"L.H.","email":"","affiliations":[],"preferred":false,"id":441458,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Healy, R. W.","contributorId":89872,"corporation":false,"usgs":true,"family":"Healy","given":"R.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":441459,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70033067,"text":"70033067 - 2008 - Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s","interactions":[],"lastModifiedDate":"2012-03-12T17:21:37","indexId":"70033067","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1801,"text":"Geomorphology","active":true,"publicationSubtype":{"id":10}},"title":"Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s","docAbstract":"The climatic controls on dune mobility, especially the relative importance of wind strength, remain incompletely understood. This is a key research problem in semi-arid northern China, both for interpreting past dune activity as evidence of paleoclimate and for predicting future environmental change. Potential eolian sand transport, which is approximately proportional to wind power above the threshold for sand entrainment, has decreased across much of northern China since the 1970s. Over the same period, effective moisture (ratio of precipitation to potential evapotranspiration) has not changed significantly. This \"natural experiment\" provides insight on the relative importance of wind power as a control on dune mobility in three dunefields of northern China (Mu Us, Otindag, and Horqin), although poorly understood and potentially large effects of human land use complicate interpretation. Dune forms in these three regions are consistent with sand transport vectors inferred from weather station data, suggesting that wind directions have remained stable and the stations adequately represent winds that shaped the dunes. The predicted effect of weaker winds since the 1970s would be dune stabilization, with lower sand transport rates allowing vegetation cover to expand. Large portions of all three dunefields remained stabilized by vegetation in the 1970s despite high wind power. Since the 1970s, trends in remotely sensed vegetation greenness and change in mobile dune area inferred from sequential Landsat images do indicate widespread dune stabilization in the eastern Mu Us region. On the other hand, expansion of active dunes took place farther west in the Mu Us dunefield and especially in the central Otindag dunefield, with little overall change in two parts of the Horqin dunes. Better ground truth is needed to validate the remote sensing analyses, but results presented here place limits on the relative importance of wind strength as a control on dune mobility in the study areas. High wind power alone does not completely destabilize these dunes. A large decrease in wind power either has little short-term effect on the dunes, or more likely its effect is sufficiently small that it is obscured by human impacts on dune stability in many parts of the study areas. ?? 2008 Elsevier B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Geomorphology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.geomorph.2008.04.004","issn":"01695","usgsCitation":"Mason, J., Swinehart, J.B., Lu, H., Miao, X., Cha, P., and Zhou, Y., 2008, Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s: Geomorphology, v. 102, no. 3-4, p. 351-363, https://doi.org/10.1016/j.geomorph.2008.04.004.","startPage":"351","endPage":"363","numberOfPages":"13","costCenters":[],"links":[{"id":213421,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.geomorph.2008.04.004"},{"id":241045,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"102","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a478de4b0c8380cd678c5","contributors":{"authors":[{"text":"Mason, J.A.","contributorId":31507,"corporation":false,"usgs":true,"family":"Mason","given":"J.A.","email":"","affiliations":[],"preferred":false,"id":439238,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Swinehart, J. B.","contributorId":25244,"corporation":false,"usgs":true,"family":"Swinehart","given":"J.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":439237,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Lu, H.","contributorId":49936,"corporation":false,"usgs":true,"family":"Lu","given":"H.","email":"","affiliations":[],"preferred":false,"id":439239,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Miao, X.","contributorId":60753,"corporation":false,"usgs":true,"family":"Miao","given":"X.","email":"","affiliations":[],"preferred":false,"id":439240,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Cha, P.","contributorId":103090,"corporation":false,"usgs":true,"family":"Cha","given":"P.","email":"","affiliations":[],"preferred":false,"id":439242,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Zhou, Y.","contributorId":70526,"corporation":false,"usgs":true,"family":"Zhou","given":"Y.","email":"","affiliations":[],"preferred":false,"id":439241,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70033066,"text":"70033066 - 2008 - Alien dominance of the parasitoid wasp community along an elevation gradient on Hawai'i Island","interactions":[],"lastModifiedDate":"2012-03-12T17:21:37","indexId":"70033066","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1018,"text":"Biological Invasions","active":true,"publicationSubtype":{"id":10}},"title":"Alien dominance of the parasitoid wasp community along an elevation gradient on Hawai'i Island","docAbstract":"Through intentional and accidental introduction, more than 100 species of alien Ichneumonidae and Braconidae (Hymenoptera) have become established in the Hawaiian Islands. The extent to which these parasitoid wasps have penetrated native wet forests was investigated over a 1,765 m elevation gradient on windward Hawai'i Island. For >1 year, malaise traps were used to continuously monitor parasitoid abundance and species richness in nine sites over three elevations. A total of 18,996 individuals from 16 subfamilies were collected. Overall, the fauna was dominated by aliens, with 44 of 58 species foreign to the Hawaiian Islands. Ichneumonidae was dominant over Braconidae in terms of both diversity and abundance, comprising 67.5% of individuals and 69.0% of species collected. Parasitoid abundance and species richness varied significantly with elevation: abundance was greater at mid and high elevations compared to low elevation while species richness increased with increasing elevation, with all three elevations differing significantly from each other. Nine species purposely introduced to control pest insects were found, but one braconid, Meteorus laphygmae, comprised 98.0% of this assemblage, or 28.3% of the entire fauna. Endemic species, primarily within the genera Spolas and Enicospilus, were collected almost exclusively at mid- and high-elevation sites, where they made up 22.1% and 36.0% of the total catch, respectively. Overall, 75.9% of species and 96.0% of individuals are inferred to parasitize Lepidoptera larvae and pupae. Our results support previous data indicating that alien parasitoids have deeply penetrated native forest habitats and may have substantial impacts on Hawaiian ecosystems. ?? 2008 Springer Science+Business Media B.V.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Biological Invasions","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s10530-008-9218-1","issn":"13873","usgsCitation":"Peck, R., Banko, P., Schwarzfeld, M., Euaparadorn, M., and Brinck, K., 2008, Alien dominance of the parasitoid wasp community along an elevation gradient on Hawai'i Island: Biological Invasions, v. 10, no. 8, p. 1441-1455, https://doi.org/10.1007/s10530-008-9218-1.","startPage":"1441","endPage":"1455","numberOfPages":"15","costCenters":[],"links":[{"id":213420,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s10530-008-9218-1"},{"id":241044,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"10","issue":"8","noUsgsAuthors":false,"publicationDate":"2008-02-06","publicationStatus":"PW","scienceBaseUri":"5059e962e4b0c8380cd4823a","contributors":{"authors":[{"text":"Peck, R.W.","contributorId":96076,"corporation":false,"usgs":true,"family":"Peck","given":"R.W.","email":"","affiliations":[],"preferred":false,"id":439235,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Banko, P.C. 0000-0002-6035-9803","orcid":"https://orcid.org/0000-0002-6035-9803","contributorId":99531,"corporation":false,"usgs":true,"family":"Banko","given":"P.C.","affiliations":[],"preferred":false,"id":439236,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Schwarzfeld, M.","contributorId":95693,"corporation":false,"usgs":true,"family":"Schwarzfeld","given":"M.","affiliations":[],"preferred":false,"id":439234,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Euaparadorn, M.","contributorId":56448,"corporation":false,"usgs":true,"family":"Euaparadorn","given":"M.","affiliations":[],"preferred":false,"id":439233,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Brinck, K.W.","contributorId":25763,"corporation":false,"usgs":true,"family":"Brinck","given":"K.W.","affiliations":[],"preferred":false,"id":439232,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70032089,"text":"70032089 - 2008 - Identifying habitat sinks: A case study of Cooper's hawks in an urban environment","interactions":[],"lastModifiedDate":"2012-03-12T17:21:28","indexId":"70032089","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3669,"text":"Urban Ecosystems","active":true,"publicationSubtype":{"id":10}},"title":"Identifying habitat sinks: A case study of Cooper's hawks in an urban environment","docAbstract":"We studied a population of Cooper's hawks (Accipiter cooperii) in Tucson, Arizona from 1994 to 2005. High rates of mortality of nestlings from an urban-related disease prompted speculation that the area represented an ecological trap and habitat sink for Cooper's hawks. In this paper, we used estimates of survival and productivity from 11years of monitoring to develop an estimate of the rate of population change, ??, for Cooper's hawks in the area. We used a Cormack-Jolly-Seber approach to estimate survival of breeding hawks, and a stochastic, stage-based matrix to estimate ??. Despite the urban-related disease, the estimate of ?? indicated that the area does not function as a habitat sink for Cooper's hawks (?? = 1.11 ?? 0.047; P = 0.0073 for the null of ?? 1). Because data required to reliably identify habitat sinks are extensive and difficult to acquire, we suggest that the concept of habitat sinks be applied cautiously until substantiated with reliable empirical evidence. ?? 2008 Springer Science+Business Media, LLC.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Urban Ecosystems","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s11252-008-0056-9","issn":"10838155","usgsCitation":"Mannan, R., Steidl, R., and Boal, C.W., 2008, Identifying habitat sinks: A case study of Cooper's hawks in an urban environment: Urban Ecosystems, v. 11, no. 2, p. 141-148, https://doi.org/10.1007/s11252-008-0056-9.","startPage":"141","endPage":"148","numberOfPages":"8","costCenters":[],"links":[{"id":214784,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s11252-008-0056-9"},{"id":242535,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"11","issue":"2","noUsgsAuthors":false,"publicationDate":"2008-04-15","publicationStatus":"PW","scienceBaseUri":"505a384de4b0c8380cd6150b","contributors":{"authors":[{"text":"Mannan, R.W.","contributorId":52915,"corporation":false,"usgs":true,"family":"Mannan","given":"R.W.","email":"","affiliations":[],"preferred":false,"id":434486,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Steidl, R.J.","contributorId":16383,"corporation":false,"usgs":true,"family":"Steidl","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":434485,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Boal, C. W.","contributorId":102614,"corporation":false,"usgs":false,"family":"Boal","given":"C.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":434487,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033729,"text":"70033729 - 2008 - A test of the cross-scale resilience model: Functional richness in Mediterranean-climate ecosystems","interactions":[],"lastModifiedDate":"2018-01-12T12:15:21","indexId":"70033729","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1452,"text":"Ecological Complexity","active":true,"publicationSubtype":{"id":10}},"title":"A test of the cross-scale resilience model: Functional richness in Mediterranean-climate ecosystems","docAbstract":"Ecological resilience has been proposed to be generated, in part, in the discontinuous structure of complex systems. Environmental discontinuities are reflected in discontinuous, aggregated animal body mass distributions. Diversity of functional groups within body mass aggregations (scales) and redundancy of functional groups across body mass aggregations (scales) has been proposed to increase resilience. We evaluate that proposition by analyzing mammalian and avian communities of Mediterranean-climate ecosystems. We first determined that body mass distributions for each animal community were discontinuous. We then calculated the variance in richness of function across aggregations in each community, and compared observed values with distributions created by 1000 simulations using a null of random distribution of function, with the same n, number of discontinuities and number of functional groups as the observed data. Variance in the richness of functional groups across scales was significantly lower in real communities than in simulations in eight of nine sites. The distribution of function across body mass aggregations in the animal communities we analyzed was non-random, and supports the contentions of the cross-scale resilience model. ?? 2007 Elsevier B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Ecological Complexity","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.ecocom.2007.11.001","issn":"1476945X","usgsCitation":"Wardwell, D., Allen, C.R., Peterson, G., and Tyre, A., 2008, A test of the cross-scale resilience model: Functional richness in Mediterranean-climate ecosystems: Ecological Complexity, v. 5, no. 2, p. 165-182, https://doi.org/10.1016/j.ecocom.2007.11.001.","startPage":"165","endPage":"182","numberOfPages":"18","costCenters":[],"links":[{"id":487718,"rank":10000,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://digitalcommons.unl.edu/natrespapers/101","text":"External Repository"},{"id":241901,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214203,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.ecocom.2007.11.001"}],"volume":"5","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e5f7e4b0c8380cd4707c","contributors":{"authors":[{"text":"Wardwell, D.A.","contributorId":18987,"corporation":false,"usgs":true,"family":"Wardwell","given":"D.A.","email":"","affiliations":[],"preferred":false,"id":442182,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Allen, Craig R. 0000-0001-8655-8272 allencr@usgs.gov","orcid":"https://orcid.org/0000-0001-8655-8272","contributorId":1979,"corporation":false,"usgs":true,"family":"Allen","given":"Craig","email":"allencr@usgs.gov","middleInitial":"R.","affiliations":[{"id":200,"text":"Coop Res Unit Seattle","active":true,"usgs":true},{"id":198,"text":"Coop Res Unit Atlanta","active":true,"usgs":true}],"preferred":true,"id":442184,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Peterson, G.D.","contributorId":102835,"corporation":false,"usgs":true,"family":"Peterson","given":"G.D.","email":"","affiliations":[],"preferred":false,"id":442185,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Tyre, A.J.","contributorId":78953,"corporation":false,"usgs":true,"family":"Tyre","given":"A.J.","email":"","affiliations":[],"preferred":false,"id":442183,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70031923,"text":"70031923 - 2008 - Are fractal dimensions of the spatial distribution of mineral deposits meaningful?","interactions":[],"lastModifiedDate":"2012-03-12T17:21:27","indexId":"70031923","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2832,"text":"Natural Resources Research","onlineIssn":"1573-8981","printIssn":"1520-7439","active":true,"publicationSubtype":{"id":10}},"title":"Are fractal dimensions of the spatial distribution of mineral deposits meaningful?","docAbstract":"It has been proposed that the spatial distribution of mineral deposits is bifractal. An implication of this property is that the number of deposits in a permissive area is a function of the shape of the area. This is because the fractal density functions of deposits are dependent on the distance from known deposits. A long thin permissive area with most of the deposits in one end, such as the Alaskan porphyry permissive area, has a major portion of the area far from known deposits and consequently a low density of deposits associated with most of the permissive area. On the other hand, a more equi-dimensioned permissive area, such as the Arizona porphyry permissive area, has a more uniform density of deposits. Another implication of the fractal distribution is that the Poisson assumption typically used for estimating deposit numbers is invalid. Based on datasets of mineral deposits classified by type as inputs, the distributions of many different deposit types are found to have characteristically two fractal dimensions over separate non-overlapping spatial scales in the range of 5-1000 km. In particular, one typically observes a local dimension at spatial scales less than 30-60 km, and a regional dimension at larger spatial scales. The deposit type, geologic setting, and sample size influence the fractal dimensions. The consequence of the geologic setting can be diminished by using deposits classified by type. The crossover point between the two fractal domains is proportional to the median size of the deposit type. A plot of the crossover points for porphyry copper deposits from different geologic domains against median deposit sizes defines linear relationships and identifies regions that are significantly underexplored. Plots of the fractal dimension can also be used to define density functions from which the number of undiscovered deposits can be estimated. This density function is only dependent on the distribution of deposits and is independent of the definition of the permissive area. Density functions for porphyry copper deposits appear to be significantly different for regions in the Andes, Mexico, United States, and western Canada. Consequently, depending on which regional density function is used, quite different estimates of numbers of undiscovered deposits can be obtained. These fractal properties suggest that geologic studies based on mapping at scales of 1:24,000 to 1:100,000 may not recognize processes that are important in the formation of mineral deposits at scales larger than the crossover points at 30-60 km. ?? 2008 International Association for Mathematical Geology.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Natural Resources Research","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s11053-008-9067-8","issn":"15207439","usgsCitation":"Raines, G.L., 2008, Are fractal dimensions of the spatial distribution of mineral deposits meaningful?: Natural Resources Research, v. 17, no. 2, p. 87-97, https://doi.org/10.1007/s11053-008-9067-8.","startPage":"87","endPage":"97","numberOfPages":"11","costCenters":[],"links":[{"id":242492,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214742,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s11053-008-9067-8"}],"volume":"17","issue":"2","noUsgsAuthors":false,"publicationDate":"2008-05-14","publicationStatus":"PW","scienceBaseUri":"5059ed5be4b0c8380cd4976a","contributors":{"authors":[{"text":"Raines, G. L.","contributorId":90720,"corporation":false,"usgs":true,"family":"Raines","given":"G.","middleInitial":"L.","affiliations":[],"preferred":false,"id":433743,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70032026,"text":"70032026 - 2008 - Predictions for an invaded world: A strategy to predict the distribution of native and non-indigenous species at multiple scales","interactions":[],"lastModifiedDate":"2012-03-12T17:21:27","indexId":"70032026","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Predictions for an invaded world: A strategy to predict the distribution of native and non-indigenous species at multiple scales","docAbstract":"Habitat models can be used to predict the distributions of marine and estuarine non-indigenous species (NIS) over several spatial scales. At an estuary scale, our goal is to predict the estuaries most likely to be invaded, but at a habitat scale, the goal is to predict the specific locations within an estuary that are most vulnerable to invasion. As an initial step in evaluating several habitat models, model performance for a suite of benthic species with reasonably well-known distributions on the Pacific coast of the US needs to be compared. We discuss the utility of non-parametric multiplicative regression (NPMR) for predicting habitat- and estuary-scale distributions of native and NIS. NPMR incorporates interactions among variables, allows qualitative and categorical variables, and utilizes data on absence as well as presence. Preliminary results indicate that NPMR generally performs well at both spatial scales and that distributions of NIS are predicted as well as those of native species. For most species, latitude was the single best predictor, although similar model performance could be obtained at both spatial scales with combinations of other habitat variables. Errors of commission were more frequent at a habitat scale, with omission and commission errors approximately equal at an estuary scale. ?? 2008 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.","largerWorkTitle":"ICES Journal of Marine Science","language":"English","doi":"10.1093/icesjms/fsn021","issn":"10543139","usgsCitation":"Reusser, D., and Lee, H., 2008, Predictions for an invaded world: A strategy to predict the distribution of native and non-indigenous species at multiple scales, in ICES Journal of Marine Science, v. 65, no. 5, p. 742-745, https://doi.org/10.1093/icesjms/fsn021.","startPage":"742","endPage":"745","numberOfPages":"4","costCenters":[],"links":[{"id":214847,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1093/icesjms/fsn021"},{"id":242599,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"65","issue":"5","noUsgsAuthors":false,"publicationDate":"2008-02-28","publicationStatus":"PW","scienceBaseUri":"505a81f9e4b0c8380cd7b82c","contributors":{"authors":[{"text":"Reusser, D.A.","contributorId":61251,"corporation":false,"usgs":true,"family":"Reusser","given":"D.A.","email":"","affiliations":[],"preferred":false,"id":434209,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lee, H. II","contributorId":9077,"corporation":false,"usgs":true,"family":"Lee","given":"H.","suffix":"II","affiliations":[],"preferred":false,"id":434208,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70032034,"text":"70032034 - 2008 - Physical and chemical changes in the foreshore of an estuarine beach: Implications for viability and development of horseshoe crab Limulus polyphemus eggs","interactions":[],"lastModifiedDate":"2012-03-12T17:21:27","indexId":"70032034","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2663,"text":"Marine Ecology Progress Series","active":true,"publicationSubtype":{"id":10}},"title":"Physical and chemical changes in the foreshore of an estuarine beach: Implications for viability and development of horseshoe crab Limulus polyphemus eggs","docAbstract":"Knowledge of conditions that favor development of eggs is important for management of species whose population growth is sensitive to early life history survival. Viability and development of the eggs of horseshoe crabs Limulus polyphemus on a sand and gravel beach were evaluated using data gathered on Delaware Bay, USA, from 18 May to 19 June 2004. Eggs were transplanted to pouches and buried in the foreshore for up to 6 wk. Viability and developmental stage were estimated as a function of oxygen and temperature gradients across the foreshore. These gradients were related to the characteristics of the intertidal foreshore sediments, beach water table changes, and frequency of inundation due to tide and swash/backwash processes. Results demonstrate the importance of interstitial temperature for development to larvae and the passive role of sediment characteristics on moisture retention and temperature. Percentage of eggs remaining in egg stage was similar across the foreshore, but more eggs developed to embryos at 0.45 of foreshore width, where moisture and gravel content were greater and interstitial temperature was lower. More eggs developed to larvae at 0.60 and 0.75 of foreshore width, where moisture and gravel content were less but interstitial temperature was higher. The beach above 0.75 of foreshore width came under the influence of wave action or full tidal inundation only during high wave heights or spring tides, and pouches at 0.75 of foreshore width were inundated only 19% of the time. Periodic wetting at this elevation did not reduce overall viability of the eggs. High wave energy events resulted in sediment activation depths to pouches at 0.30 of foreshore width, where loss of eggs due to wave activation was the most important control on the development of eggs. ?? Inter-Research 2008.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Marine Ecology Progress Series","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.3354/meps07211","issn":"01718630","usgsCitation":"Jackson, N., Smith, D., and Nordstrom, K., 2008, Physical and chemical changes in the foreshore of an estuarine beach: Implications for viability and development of horseshoe crab Limulus polyphemus eggs: Marine Ecology Progress Series, v. 355, p. 209-218, https://doi.org/10.3354/meps07211.","startPage":"209","endPage":"218","numberOfPages":"10","costCenters":[],"links":[{"id":476882,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.3354/meps07211","text":"Publisher Index Page"},{"id":214932,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3354/meps07211"},{"id":242693,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"355","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a7a6ee4b0c8380cd78ee1","contributors":{"authors":[{"text":"Jackson, N.L.","contributorId":104189,"corporation":false,"usgs":true,"family":"Jackson","given":"N.L.","email":"","affiliations":[],"preferred":false,"id":434247,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Smith, D. R. 0000-0001-6074-9257","orcid":"https://orcid.org/0000-0001-6074-9257","contributorId":44108,"corporation":false,"usgs":true,"family":"Smith","given":"D. R.","affiliations":[{"id":365,"text":"Leetown Science Center","active":true,"usgs":true}],"preferred":false,"id":434246,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Nordstrom, K.F.","contributorId":17733,"corporation":false,"usgs":true,"family":"Nordstrom","given":"K.F.","email":"","affiliations":[],"preferred":false,"id":434245,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70032035,"text":"70032035 - 2008 - Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:21:27","indexId":"70032035","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":835,"text":"Applied Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA","docAbstract":"Despite the ecological and economic importance of Great Salt Lake (GSL), little is known about the input and biogeochemical cycling of nutrients and trace elements in the lake. In response to increasing public concern regarding anthropogenic inputs to the GSL ecosystem, the US Geological Survey (USGS) and US Fish and Wildlife Service (USFWS) initiated coordinated studies to quantify and evaluate the significance of nutrient and Hg inputs into GSL. A 6??? decrease in ??15N observed in brine shrimp (Artemia franciscana) samples collected from GSL during summer time periods is likely due to the consumption of cyanobacteria produced in freshwater bays entering the lake. Supporting data collected from the outflow of Farmington Bay indicates decreasing trends in ??15N in particulate organic matter (POM) during the mid-summer time period, reflective of increasing proportions of cyanobacteria in algae exported to GSL on a seasonal basis. The C:N molar ratio of POM in outflow from Farmington Bay decreases during the summer period, supportive of the increased activity of N fixation indicated by decreasing ??15N in brine shrimp and POM. Although N fixation is only taking place in the relatively freshwater inflows to GSL, data indicate that influx of fresh water influences large areas of the lake. Separation of GSL into two distinct hydrologic and geochemical systems from the construction of a railroad causeway in the late 1950s has created a persistent and widespread anoxic layer in the southern part of GSL. This anoxic layer, referred to as the deep brine layer (DBL), has high rates of SO42 - reduction, likely increasing the Hg methylation capacity. High concentrations of methyl mercury (CH3Hg) (median concentration = 24 ng/L) were observed in the DBL with a significant proportion (31-60%) of total Hg in the CH3Hg form. Hydroacoustic and sediment-trap evidence indicate that turbulence introduced by internal waves generated during sustained wind events can temporarily mix the elevated CH3Hg concentrations in the DBL with the more biologically active upper brine layer (UBL). Brine shrimp collected during the summer/fall time periods contained elevated Hg concentrations (median concentration = 0.34 mg/kg, dry weight (dw)) relative to samples collected during the spring (median concentration < 0.2 mg/kg, dw). Higher Hg in brine shrimp during the summer and fall may reflect the higher proportion of adult brine shrimp during this time period, resulting in an increased time for bioaccumulation of Hg. Eared grebes (Podiceps nigricollis) consume brine shrimp from GSL during the fall molting period. Median Hg concentrations in eared grebe livers increased by almost three times during the 3-5 month fall molting period. Selected duck species utilizing GSL have consistently exceeded the US Environmental Protection Agency (USEPA) screening level for Hg (0.3 mg/kg Hg wet weight), resulting in the issuance of warnings against unlimited human consumption of breast muscle tissue.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Applied Geochemistry","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.apgeochem.2008.03.002","issn":"08832927","usgsCitation":"Naftz, D., Angeroth, C., Kenney, T., Waddell, B., Darnall, N., Silva, S., Perschon, C., and Whitehead, J., 2008, Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA: Applied Geochemistry, v. 23, no. 6, p. 1731-1744, https://doi.org/10.1016/j.apgeochem.2008.03.002.","startPage":"1731","endPage":"1744","numberOfPages":"14","costCenters":[],"links":[{"id":242726,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214964,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.apgeochem.2008.03.002"}],"volume":"23","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ec5ae4b0c8380cd49204","contributors":{"authors":[{"text":"Naftz, D.","contributorId":37158,"corporation":false,"usgs":true,"family":"Naftz","given":"D.","affiliations":[],"preferred":false,"id":434249,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Angeroth, C.","contributorId":53607,"corporation":false,"usgs":true,"family":"Angeroth","given":"C.","email":"","affiliations":[],"preferred":false,"id":434251,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kenney, T.","contributorId":93281,"corporation":false,"usgs":true,"family":"Kenney","given":"T.","email":"","affiliations":[],"preferred":false,"id":434255,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Waddell, B.","contributorId":17007,"corporation":false,"usgs":true,"family":"Waddell","given":"B.","email":"","affiliations":[],"preferred":false,"id":434248,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Darnall, N.","contributorId":86551,"corporation":false,"usgs":true,"family":"Darnall","given":"N.","affiliations":[],"preferred":false,"id":434254,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Silva, S.","contributorId":68518,"corporation":false,"usgs":true,"family":"Silva","given":"S.","affiliations":[],"preferred":false,"id":434253,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Perschon, C.","contributorId":52403,"corporation":false,"usgs":true,"family":"Perschon","given":"C.","email":"","affiliations":[],"preferred":false,"id":434250,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Whitehead, J.","contributorId":54409,"corporation":false,"usgs":true,"family":"Whitehead","given":"J.","affiliations":[],"preferred":false,"id":434252,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70032043,"text":"70032043 - 2008 - Using semi-permeable membrane devices and stable nitrogen isotopes to detect anthropogenic influences on the Truckee River, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:21:28","indexId":"70032043","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1535,"text":"Environmental Engineering Science","active":true,"publicationSubtype":{"id":10}},"title":"Using semi-permeable membrane devices and stable nitrogen isotopes to detect anthropogenic influences on the Truckee River, USA","docAbstract":"Stable nitrogen isotopes (??15N) and semipermeable membrane devices (SPMDs) were used together to provide evidence of potential anthropogenic connections to aquatic organisms in the Truckee River, which flows through the Reno/Sparks metropolitan area in Nevada. Crayfish, snail, and periphyton ??15N values, and SPMD toxicity data collected during high and low flow periods at seven primary sites on the river were used with water quality and flow data for the assessment. All biota showed an increase of ??15N on both dates at sites downstream of inflows of a water-quality impaired tributary and urban drain relative to upstream. In addition, most of the lowest ??15N values on each date occurred at the most downstream site on the river. SPMDs sample lipophilic organic contaminants and can be used to assess organic contaminant toxicity to aquatic organisms because they use a membrane that mimics organic contaminant uptake by fish. In this study, results from a fluoroscan test [pyrene index (PI)] of SPMD extracts that responds to higher molecular weight polycyclic aromatic hydrocarbons (PAHs) showed patterns similar to stable isotope data, although observed peaks in PI values occurred in the urban area upstream of where peak ??15N values occurred. The CYP1A biomarker test, which responds to PAHs, certain polychlorinated biphenyls (PCBs), and organochlorines, showed peak toxic equivalents (TEQ) values farther downstream of the urban area. Thus, it is likely that PAHs were contributing to toxicity in the urban area, whereas other nonurban sources of organic carbon may have been present farther downstream. The combined use of stable isotope measurements and SPMDs provided a means of simultaneously examining whether aquatic biota are incorporating constituents from potential food sources (via stable isotopes) or exposure through water (via SPMDs). ?? Mary Ann Liebert, Inc. 2008.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Environmental Engineering Science","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1089/ees.2007.0090","issn":"10928758","usgsCitation":"Saito, L., Rosen, M.R., Chandra, S., Fritsen, C., Arufe, J., and Redd, C., 2008, Using semi-permeable membrane devices and stable nitrogen isotopes to detect anthropogenic influences on the Truckee River, USA: Environmental Engineering Science, v. 25, no. 4, p. 585-600, https://doi.org/10.1089/ees.2007.0090.","startPage":"585","endPage":"600","numberOfPages":"16","costCenters":[],"links":[{"id":214590,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1089/ees.2007.0090"},{"id":242329,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"25","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bc09ce4b08c986b32a20e","contributors":{"authors":[{"text":"Saito, L.","contributorId":59402,"corporation":false,"usgs":true,"family":"Saito","given":"L.","email":"","affiliations":[],"preferred":false,"id":434288,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Rosen, Michael R.","contributorId":43096,"corporation":false,"usgs":true,"family":"Rosen","given":"Michael","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":434285,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Chandra, S.","contributorId":68867,"corporation":false,"usgs":true,"family":"Chandra","given":"S.","email":"","affiliations":[],"preferred":false,"id":434289,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Fritsen, C.H.","contributorId":43979,"corporation":false,"usgs":true,"family":"Fritsen","given":"C.H.","email":"","affiliations":[],"preferred":false,"id":434286,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Arufe, J.A.","contributorId":53184,"corporation":false,"usgs":true,"family":"Arufe","given":"J.A.","email":"","affiliations":[],"preferred":false,"id":434287,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Redd, C.","contributorId":26514,"corporation":false,"usgs":true,"family":"Redd","given":"C.","email":"","affiliations":[],"preferred":false,"id":434284,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70032805,"text":"70032805 - 2008 - Long-term changes in the phosphorus loading to and trophic state of the Salton Sea, California","interactions":[],"lastModifiedDate":"2018-02-06T12:19:15","indexId":"70032805","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1919,"text":"Hydrobiologia","onlineIssn":"1573-5117","printIssn":"0018-8158","active":true,"publicationSubtype":{"id":10}},"title":"Long-term changes in the phosphorus loading to and trophic state of the Salton Sea, California","docAbstract":"The Salton Sea (Sea) is a eutrophic to hypereutrophic lake characterized by high nutrient concentrations, low water clarity, and high biological productivity. Based on dissolved phosphorus (P) and nitrogen (N) concentrations and N:P ratios, P is typically the limiting nutrient in the Sea and, therefore, should be the primary nutrient of concern when considering management efforts. Flows in the major tributaries to the Sea have been measured since 1965, whereas total P (TP) concentrations were only measured intermittently by various agencies since 1968. These data were used to estimate annual P loading from 1965 to 2002. Annual loads have increased steadily from ???940,000 kg around 1968 to ???1,450,000 kg in 2002 (???55% increase), primarily a result of increased TP concentrations and loads in the New River. Although the eutrophic condition of the Salton Sea is of great concern, only limited nutrient data are available for the Sea. It is difficult to determine whether the eutrophic state of the Sea has degraded or possibly even improved slightly in response to the change in P loading because of variability in the data and changes in the sampling and analytical methodologies. ?? 2008 Springer Science+Business Media B.V.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrobiologia","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s10750-008-9312-5","issn":"00188158","usgsCitation":"Robertson, D.M., Schladow, S., and Holdren, G., 2008, Long-term changes in the phosphorus loading to and trophic state of the Salton Sea, California: Hydrobiologia, v. 604, no. 1, p. 21-36, https://doi.org/10.1007/s10750-008-9312-5.","startPage":"21","endPage":"36","numberOfPages":"16","costCenters":[],"links":[{"id":241605,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":213930,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s10750-008-9312-5"}],"volume":"604","issue":"1","noUsgsAuthors":false,"publicationDate":"2008-03-18","publicationStatus":"PW","scienceBaseUri":"505a497ee4b0c8380cd6865c","contributors":{"authors":[{"text":"Robertson, Dale M. 0000-0001-6799-0596 dzrobert@usgs.gov","orcid":"https://orcid.org/0000-0001-6799-0596","contributorId":150760,"corporation":false,"usgs":true,"family":"Robertson","given":"Dale","email":"dzrobert@usgs.gov","middleInitial":"M.","affiliations":[{"id":37947,"text":"Upper Midwest Water Science Center","active":true,"usgs":true}],"preferred":true,"id":437989,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Schladow, S.G.","contributorId":92791,"corporation":false,"usgs":true,"family":"Schladow","given":"S.G.","email":"","affiliations":[],"preferred":false,"id":437991,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Holdren, G.C.","contributorId":63630,"corporation":false,"usgs":true,"family":"Holdren","given":"G.C.","email":"","affiliations":[],"preferred":false,"id":437990,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ]}