2,151 research outputs found
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Summary report to assist development of ecosystem flow recommendations for the Coast Fork and Middle Fork of the Willamette River, Oregon
Introduction The Willamette River Flow Project The Nature Conservancy (TNC) and the U. S. Army Corps of Engineers (USACE) are collaborating on a project to determine environmental flow requirements for the Willamette River and its tributaries and to design and test alternative flow releases from the dams that can meet these requirements. The project is part of the Sustainable Rivers Project (SRP), a national effort by TNC and USACE to investigate opportunities to change Corps Dam operations (“reoperate”) to achieve more ecologically sustainable flows, while maintaining or enhancing project benefits. Through the SRP, TNC and USACE have developed and tested a process for identifying and refining environmental flow objectives (Richter et. al. 2006). The process utilizes a series of steps to define environmental flow requirements, implement changes in operation of dams to meet those flow objectives, monitor and model the effects of those changes on both the river ecosystem and the operation of the dams, and refine over time. The Willamette River Flow Project is being conducted in conjunction with the USACE Willamette Floodplain Restoration Feasibility Study. This feasibility study is designed to identify opportunities to restore natural floodplain function in the Willamette River basin to provide ecosystem restoration, natural flood storage, and other benefits. The initial study phase has focused on the Coast and Middle Forks of the Willamette River. These subbasins contain 6 of the 13 dams in the Willamette system; their operation has implications for the operation of the other dams in the system. To date, the Floodplain Restoration Study has focused on two important aspects of the aquatic ecosystem: 1) identifying habitat, flow and water quality requirements for a variety of aquatic and floodplain species; and 2) describing and evaluating the current channel and floodplain morphological characteristics, and their changes from historic condition. Partners in the feasibility study include the Willamette Partnership, the Willamette Middle and Coast Fork Watershed councils, the Oregon Department of Fish and Wildlife, and The Nature Conservancy. There is also an inter-disciplinary expert and stakeholder group of approximately 20 federal, state and local entities plus private landowners that informs the process. The Willamette River Flow Project will build upon the Floodplain Restoration study by developing environmental flow requirements for the reaches downstream of the Corps dams and linking those flows to opportunities for stream channel and floodplain restoration, and to improvement in operation of the dams. Given the existing floodplain restoration study, the initial SRP efforts will use the Coast and Middle Forks and the mainstem Willamette immediately downstream of these tributaries as a pilot study that can be replicated in the rest of the Willamette system. River flows from both subbasins have been greatly affected by operation of the dams: 56% of the drainage area of the Coast Fork and 87% of the Middle Fork drain into USACE reservoirs. General effects of the reservoirs include reduced peak flows, lower spring flows, increased summer low flows, and infrequent bankfull and out-of-bank flows. The Willamette Flow Project partners anticipate the study will be expanded in the future to encompass the other major tributaries controlled by USACE dams.Prepared for Sustainable Rivers Project of the Nature Conservancy and the U.S. Army Corps of Engineers
Can uptake length in strams be determined by nutrient addition experiments? Results from an interbiome comparison study
Nutrient uptake length is an important parnmeter tor quantifying nutrient cycling in streams. Although nutrient tracer additions are the preierred method for measuring uptake length under ambient nutrient concentrations, short-term nutrient addition experiments have more irequently been used to estimate uptake length in streams. Theoretical analysis of the relationship between uptake length determined by nutrient addition experiments (Sw\u27) and uptake length determined by tracer additions (Sw)predicted that Sw\u27 should be consistently longer than 5, , and that the overestimate of uptake length by Sw( should be related to the level of nutrient addition above ambient concentrations and the degree of nutrient limitation. To test these predictions, we used data irom an interbiorne study of NH,- uptake length in which 15NH,- tracer and short-term NH,-a ddition experiments were performed in 10 streams using a uniform experimental approach. The experimental results largely contirmed the theoretical predictions: sw\u27 was consistently longer than Sw and Sw\u27:Sw ratios were directly related to the level of NH,- addition and to indicatvrs of N limitation. The experimentally derived Sw\u27:Sw, ratios were used with the theoretical results to infer the N limitation status of each stream. Together, the theoretical and experimental results showed the tracer experiments should be used whenever possible to determine nutrient uptake length in streams. Nutrient addition experiments may be useful for comparing uptake lengths between different streams or cliiferent times in the same stream. however, provided that nutrient additions are kept as low as possible and of similar miagnitude
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Issues surrounding the Biota of the Tualatin River Basin
Tributaries of the Tualatin River cascade down high gradient slopes for relatively short distances, then flow into the low gradient mainstem which meanders for much of its length. The gentle, east-facing slopes of Oregon's Coast Range provide the geomorphic and climatic template for the watershed's patterns of discharge, water quality, and biological distribution. Human activity has altered this stream for over 150 years. Navigation, agriculture, and dam diversion at Lake Oswego were early impacts on Tualatin tributaries and mainstem. Demands from increasing urban development, such as domestic water use and streamside development, are likely to further exacerbate alterations to flow regimes, in-stream structure, and channel morphology.
Biological communities within the stream as well as organisms inhabiting adjacent riparian vegetation and hillslopes are influenced strongly by physical processes across the entire watershed (Gregory et al 1991). From upslope headwaters through meandering mainstem, the biota comprise a continuum of organisms whose composition, quantity, and diversity reflect upstream and downstream phenomena (Vannote et al. 1980). In this report we will emphasize this landscape perspective by considering patterns of physical and biological processes across the entire basin. The purpose· of this report is to review the available information on the Tualatin River basin biota, to suggest the kinds of biological data still needed, and to identify potential problems related to recovery of biological integrity in this watershed
Factors affecting ammonium uptake in streams - an inter-biome perspective
The Lotic Intersite Nitrogen experiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of \u275~-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake
Validation of the Edinburgh Claudication Questionnaire in 1st generation Black African-Caribbean and South Asian UK migrants: A sub-study to the Ethnic-Echocardiographic Heart of England Screening (E-ECHOES) study
<p>Abstract</p> <p>Background</p> <p>We determined the diagnostic accuracy of the Edinburgh Claudication Questionnaire (ECQ) in 1<sup>st </sup>generation Black African-Caribbean UK migrants as previous diagnostic questionnaires have been found to be less accurate in this population. We also determined the diagnostic accuracy of translated versions of the ECQ in 1<sup>st </sup>generation South Asian UK migrants, as this has not been investigated before.</p> <p>Methods</p> <p>Subjects were recruited from the Ethnic-Echocardiographic Heart of England Screening (E-ECHOES) study, a community based screening survey for heart failure in minority ethnic groups. Translated versions of the ECQ were prepared following a recognised protocol. All participants attending screening between October 2007 and February 2009 were asked to complete the ECQ in the language of their choice (English, Punjabi, Bengali, Urdu, Hindi or Gujarati). Subjects answering positively to experiencing leg pain or discomfort on walking were asked to return to have Ankle Brachial Pressure Index (ABPI) measured.</p> <p>Results</p> <p>154 out of 2831 subjects participating in E-ECHOES (5.4%) were eligible to participate in this sub-study, for which 74.3% returned for ABPI assessment. Non-responders were younger than participants (59[9] vs. 65[11] years; p = 0.015). Punjabi, English and Bengali questionnaires identified participants with Intermittent Claudication, so these questionnaires were assessed. The sensitivities (SN), specificities (SP), positive (PPV) and negative (NPV) predictive values were calculated. English: SN: 50%; SP: 68%; PPV: 43%; NPV: 74%. Punjabi: SN: 50%; SP: 87%; PPV: 43%; NPV: 90%. Bengali: SN: 33%; SP: 50%; PPV: 13%; NPV: 73%. There were significant differences in diagnostic accuracy between the 3 versions (Punjabi: 83.8%; Bengali: 45%; English: 62.2%; p < 0.0001). No significant differences were found in sensitivity and specificity between illiterate and literate participants in any of the questionnaires and there was no significant different difference between those under and over 60 years of age.</p> <p>Conclusions</p> <p>Our findings suggest that the ECQ is not as sensitive or specific a diagnostic tool in 1<sup>st </sup>generation Black African-Caribbean and South Asian UK migrants than in the Edinburgh Artery Study, reflecting the findings of other diagnostic questionnaires in these minority ethnic groups. However this study is limited by sample size so conclusions should be interpreted with caution.</p
Fanny Copeland and the geographical imagination
Raised in Scotland, married and divorced in the English south, an adopted Slovene, Fanny Copeland (1872 – 1970) occupied the intersection of a number of complex spatial and temporal conjunctures. A Slavophile, she played a part in the formation of what subsequently became the Kingdom of Yugoslavia that emerged from the First World War. Living in Ljubljana, she facilitated the first ‘foreign visit’ (in 1932) of the newly formed Le Play Society (a precursor of the Institute of British Geographers) and guided its studies of Solčava (a then ‘remote’ Alpine valley system) which, led by Dudley Stamp and commended by Halford Mackinder, were subsequently hailed as a model for regional studies elsewhere. Arrested by the Gestapo and interned in Italy during the Second World War, she eventually returned to a socialist Yugoslavia, a celebrated figure. An accomplished musician, linguist, and mountaineer, she became an authority on (and populist for) the Julian Alps and was instrumental in the establishment of the Triglav National Park. Copeland’s role as participant observer (and protagonist) enriches our understanding of the particularities of her time and place and illuminates some inter-war relationships within G/geography, inside and outside the academy, suggesting their relative autonomy in the production of geographical knowledge
Chromosomal-level assembly of the Asian Seabass genome using long sequence reads and multi-layered scaffolding
We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics
Thinking outside the channel : modeling nitrogen cycling in networked river ecosystems
Author Posting. © Ecological Society of America, 2011. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Frontiers in Ecology and the Environment 9 (2011): 229–238, doi:10.1890/080211.Agricultural and urban development alters nitrogen and other biogeochemical cycles in rivers worldwide. Because such biogeochemical processes cannot be measured empirically across whole river networks, simulation models are critical tools for understanding river-network biogeochemistry. However, limitations inherent in current models restrict our ability to simulate biogeochemical dynamics among diverse river networks. We illustrate these limitations using a river-network model to scale up in situ measures of nitrogen cycling in eight catchments spanning various geophysical and land-use conditions. Our model results provide evidence that catchment characteristics typically excluded from models may control river-network biogeochemistry. Based on our findings, we identify important components of a revised strategy for simulating biogeochemical dynamics in river networks, including approaches to modeling terrestrial–aquatic linkages, hydrologic exchanges between the channel, floodplain/riparian complex, and subsurface waters, and interactions between coupled biogeochemical cycles.This research was supported by NSF (DEB-0111410).
Additional support was provided by NSF for BJP and
SMT (DEB-0614301), for WMW (OCE-9726921 and
DEB-0614282), for WHM and JDP (DEB-0620919), for
SKH (DEB-0423627), and by the Gordon and Betty
Moore Foundation for AMH, GCP, ESB, and JAS, and by
an EPA Star Fellowship for AMH
A meta-analysis of the investment-uncertainty relationship
In this article we use meta-analysis to investigate the investment-uncertainty relationship. We focus on the direction and statistical significance of empirical estimates. Specifically, we estimate an ordered probit model and transform the estimated coefficients into marginal effects to reflect the changes in the probability of finding a significantly negative estimate, an insignificant estimate, or a significantly positive estimate. Exploratory data analysis shows that there is little empirical evidence for a positive relationship. The regression results suggest that the source of uncertainty, the level of data aggregation, the underlying model specification, and differences between short- and long-run effects are important sources of variation in study outcomes. These findings are, by and large, robust to the introduction of a trend variable to capture publication trends in the literature. The probability of finding a significantly negative relationship is higher in more recently published studies. JEL Classification: D21, D80, E22 1
Digital Signal Processing Research Program
Contains table of contents for Section 2, an introduction, reports on sixteen research projects and a list of publications.Bose CorporationMIT-Woods Hole Oceanographic Institution Joint Graduate Program in Oceanographic EngineeringAdvanced Research Projects Agency/U.S. Navy - Office of Naval Research Grant N00014-93-1-0686Lockheed Sanders, Inc./U.S. Navy - Office of Naval Research Contract N00014-91-C-0125U.S. Air Force - Office of Scientific Research Grant AFOSR-91-0034AT&T Laboratories Doctoral Support ProgramAdvanced Research Projects Agency/U.S. Navy - Office of Naval Research Grant N00014-89-J-1489U.S. Navy - Office of Naval Research Grant N00014-93-1-0686National Science Foundation FellowshipMaryland Procurement Office Contract MDA904-93-C-4180U.S. Navy - Office of Naval Research Grant N00014-91-J-162
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