Consulta: subjectFacets:"Chesapeake Bay"
Registros recuperados: 24
Data/hora: 06/06/2024 10:42:42

Altered Ecological Flows Blur Boundaries in Urbanizing Watersheds
Provedor de dados: 7
Autores: Lookingbill, Todd R; University of Maryland Center for Environmental Science; tlooking@richmond.edu; Kaushal, Sujay S; University of Maryland Center for Environmental Science;; Elmore, Andrew J; University of Maryland Center for Environmental Science;; Gardner, Robert; University of Maryland Center for Environmental Science;; Eshleman, Keith N; University of Maryland Center for Environmental Science;; Hilderbrand, Robert H; University of Maryland Center for Environmental Science;; Morgan, Raymond P; University of Maryland Center for Environmental Science;; Boynton, Walter R; University of Maryland Center for Environmental Science;; Palmer, Margaret A; University of Maryland Center for Environmental Science;; Dennison, William C; University of Maryland Center for Environmental Science;.
The relevance of the boundary concept to ecological processes has been recently questioned. Humans in the post-industrial era have created novel lateral transport fluxes that have not been sufficiently considered in watershed studies. We describe patterns of land-use change within the Potomac River basin and demonstrate how these changes have blurred traditional ecosystem boundaries by increasing the movement of people, materials, and energy into and within the basin.  We argue that this expansion of ecological commerce requires new science, monitoring, and management strategies focused on large rivers and suggest that traditional geopolitical and economic boundaries for environmental decision making be appropriately revised. Effective mitigation of the...
Tipo: Peer-Reviewed Synthesis
Palavras-chave: Catchment ecology; Chesapeake Bay; Interdisciplinary science; Large river; Potomac River; Restoration; Urban metabolism.
Ano: 2009

Combined effects of temperature-salinity on larval survival of the Eastern oyster Crassostrea virginica in the Maryland portion of the Chesapeak Bay (USA)
Provedor de dados: 5
Autores: Goulletquer, Philippe; Heral, Maurice; Prou, Jean.
Oyster landings in the Maryland portion of the Chesapeake Bay have declined by more than 50fold since the early part of the century, despite intensive management efforts. The annual shell repletion program is the most critical programmatic element to effect recovery of the ailing Eastern oyster Crassotrea virginica stock and fishery. The overall efficacy of shell repletion management depends primarily on the success of spat settlement on the planted shell, and furthermore on their survival rate. The Operations Research techniques and mathematical programming developed by Rothschild et al. (1991) attempt to maximize spat recruitment to the oyster stock subject to a series of operational constraints. Allocation and timing of shell deployment are the most...
Tipo: Text
Palavras-chave: Larval; Settlement; USA; Chesapeake Bay; Crassotrea virginica; Oysters.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/1994/publication-3074.pdf

Use of the kriging method for the stock assessment of oysters in the Chesapeake Bay
Provedor de dados: 5
Autores: Bacher, Cedric; Chai, Ai-ling; Goulletquer, Philippe.
The krlging technique Is now employed ln more and more fields: mlnlng (Journel. 1977), hydrology (Delhomme, 197B; Shamsi et al" 1988; Dingman et al" 1988), fishery (Conan, 1989) and ecology (Robertson, 1987; Schotzko and O'Keeffe, 1989, 1990). Recent developments of the mathematlcal theory tend to extend the number of applications where Il may be used. Baslcally defined for the case of a statlonary spatial process, It now encompasses more general processes assuming less and less strong hypotheses (Intrinsic hypothesls, Intrlnsic generalised hypothesis, disjunctive krlglng). In its most general formulation, it allows to study the spatial structure of a process including large scale or local trends. The basic idea remains to take Into account the spatial...
Tipo: Text
Palavras-chave: Kringing technique; Stock assessment; Oysters; Crassostrea virginica; Chesapeake Bay.
Ano: 1991
URL: http://archimer.ifremer.fr/doc/00200/31110/29518.pdf

Dynamics of an estuarine ecosystem: Long-term trends in the macrobenthic communities of Chesapeake bay, (1985-1993)
Provedor de dados: 5
Autores: Dauer, Dm.
Long-term trends in subtidal macrobenthic communities of the lower Chesapeake Bay, USA, were examined using data collected quarterly (March, June, September and December) fr om 1985 through 1993 at 16 stations along a salinity gradient from tidal freshwater regions of the major tributaries (James, York and Rappahannock rivers) to the polyhaline region of the mainstem of Chesapeake Bay. In March 1989 two stations were added to the program in the mesohaline region of the Southern Branch of the Elizabeth River, a region characterized by contaminated sediments. A non-parametric trend analysis procedure was applied to five parameters characterizing macrobenthic community structure: community biomass, species richness, abundance of individuals, proportion of...
Tipo: Text
Palavras-chave: Chesapeake Bay; Benthos; Trends; Estuary; Eutrophication.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20399/18066.pdf

Aspects biométriques et biochimiques de la croissance de l'huître Crassostrea virginica en élevage suspendu à Solomons (Baie de Chesapeake)
Provedor de dados: 5
Autores: Goulletquer, Philippe; Prou, Jean; Heral, Maurice.
Growth and proximate biochemical composition of the American oyster Crassostrea virginica were studied in the Patuxent river (Maryland), located in the middle reach of the Chesapeake bay (U.S.A.). The effects of stocking densities and environmental variables (depth, temperature) were examined in 1989-1990 on oyster population by using off-bottom culture. No significant density effect was observed on the shell growth, which is described by using a seasonally oscillating function. In contrast, the meat growth and the proximate biochemical composition were bath affected by the stacking density and the depth location. The variability of the resulting effects was observed based on a seasonal trend. Different hypothesis mainly related tO environmental conditions...
Tipo: Text
Palavras-chave: USA; Chesapeake Bay; Oysters; Growth; Biochemical composition; Crassostrea virginica; Croissance; USA; Chesapeake Bay; Huîtres; Biochimie; Biométrie; Crassotrea virginica.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/1994/publication-3076.pdf

The decline of Chesapeake Bay oyster population : a century of habitat destruction and overfishing
Provedor de dados: 5
Autores: Rotschild, B. J.; Ault, J. S.; Goulletquer, Philippe; Jensen, W. P.; Heral, Maurice.
The  oyster population in the Maryland portion of the Chesapeake Bay has declined b y more than 38-fold since the early part of the century. Although the effects of fishing have been implicated, the decline has been attributed primarily to water quality and recently oyster disease. The decline has also been thought to have affected the biota and chemistry of the Bay. Our analysis provides a quantitative demonstration that the long-term declines are largely the result of habitat loss related to over fishing early in the century, stock over fishing, early in the century' through the recent times. Furthermore, the major ecological effects on Chesapeake Bay occurred well-before World War 1/, before industrialization and the prevalence of disease
Tipo: Text
Palavras-chave: USA; Chesapeake Bay; Prevalence of disease; Industrialization; Diseases; Crassostrea virginica; Oysters.
Ano: 1991
URL: http://archimer.ifremer.fr/doc/1991/acte-3058.pdf

Causes of decline of oyster production (Crassostrea virginica) in the Maryland portion of the Chesapeake Bay : a literature study
Provedor de dados: 5
Autores: Goulletquer, Philippe; Heral, Maurice; Rotschild, Brian.
The historical landings of Eastern oyster Crassostrea virginica are described for the Maryland part of the Chesapeake Bay. The different trends are analyzed concurrently with the main events and management strategies which occurred. Three main periods are identified : (1) the great fishery when annual oyster landings from 1840 to 1890 reached 600,000 metric tons. This period was characterized by gross overfishing and the destruction of oyster habitat by the oyster gears; (2) the reduced but stable landings from 1900 to 1980, with failure of the reseeding plan connected to heavy sedimentation and anoxie summer conditions. Landings did not exceed 80,000 metric tons; (3) the large decrease of production (1981-1988), with landings as low as 15,000 metric tons...
Tipo: Text
Palavras-chave: Production; Chesapeake Bay; Mortalities; Crassostrea virginica; Oysters; Production; Chesapeake Bay; Mortalités; Crassostrea virginica; Huîtres.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/1994/publication-3081.pdf

Breeding and Domestication of Eastern Oyster (  Crassostrea virginica  ) Lines for Culture in the Mid-Atlantic, Usa: Line Development and Mass Selection for Disease Resistance
Provedor de dados: 5
Autores: Frank-lawale, Anu; Allen, Standish K.; Degremont, Lionel.
A selective breeding program for Crassostrea virginica was established in 1997 as part of an initiative in Virginia to address declining oyster harvests caused by the two oyster pathogens Haplosporidium nelsoni (MSX) and Perkinsus marinus (Dermo). Housed in the Aquaculture Genetics and Breeding Technology Center (ABC), the objective of the program was to develop and disseminate disease-resistant lines that would enable an oyster culture industry. Today, culture of disease-resistant cultivars accounts formore than 90%of oyster production in the state, where 28.1 million half-shell oysters and 2 billion eyed larvae were sold in 2012. Results of our line development program as of 2006 are reported. Eight ABC lines from 3 genetic groups—East Coast (EC),...
Tipo: Text
Palavras-chave: Crassostrea gigas; Oysters; Selective breeding; Disease resistance; Chesapeake Bay; Growth; Genetic improvement; MSX; Dermo.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00188/29950/28395.pdf

Modelisation of oyster shell growth at 3 stations in the Patuxent river (Chesapeake Bay)
Provedor de dados: 5
Autores: Prou, Jean; Goulletquer, Philippe; Bacher, Cedric.
In oyster production area the determination of the stock, estimation of mortality and growth rates are determinant for knowledge of the fishery. Growth models can be used to predict the time to reach marketable size (76 mm in Chesapeake Bay). They are also important in term of management, when they can predict the future value of the stock (Askew, 1978). Oyster growth models can be built by analysing growth of natural oysters but absolute age is orten unknown. Many authors report growth data in Chesapeake Bay for suspended oyster culture. Unfortunalely, modelisation of the growth was not developed. In that study oyster, shell growth models have been established at three stations in the Patuxent river. Seasonal eITects on growth were integrated in the model
Tipo: Text
Palavras-chave: Modelisation; Oysters; Crassostrea virginica; Growth; Chesapeake Bay.
Ano: 1991
URL: http://archimer.ifremer.fr/doc/00200/31109/29512.pdf

Barriers to Eastern Oyster Aquaculture Expansion in Virginia
Provedor de dados: 5
Autores: Beckensteiner, Jennifer; Kaplan, David; Scheld, Andrew M.
The eastern oyster once provided major societal and ecosystem benefits, but these benefits have been threatened in recent decades by large declines in oyster harvests. In many areas, recovery of oyster aquaculture faces significant societal opposition and spatial constraints limiting its ability to meet expectations regarding future food needs and provision of ecosystem services. In Virginia, oyster aquaculture has begun to expand, concurrent with an increase in subaqueous leased areas (over 130,000 acres of grounds are currently leased). Though private leases must in theory be used for oyster production, in practice, they can be held for other reasons, such as speculation or intentional exclusion of others. These factors have led to large variation over...
Tipo: Text
Palavras-chave: Crassostrea virginica; Oyster aquaculture; Chesapeake Bay; Spatial management; User conflicts.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00611/72337/71162.pdf

Oyster production in Europe and in the Chesapeake Bay
Provedor de dados: 5
Autores: Heral, Maurice.
This report has been achieved during a work as short-term consultant in Chesapeake Biological Laboratory (University of Maryland) in the Laboratory of Prof. B. J. Rothschild, for a period from July 7 to August 7 1989 and at Ifremer Laboratory of La Tremblade. The terms of reference of the consultance were : to compare the oyster fishery researches between the Chesapeake Bay and Europe, particularly in reference to the French coast. To evaluate the on-going Chesapeake Bay oyster stock assessment project and to provide its comments and recommendations. To work on spat settlement in the Bay. This study was funded by the National Oceanic and Atmospheric Administration, by the Maryland Department of Natural Resources under contract F 1666-89-008 and by the...
Tipo: Text
Palavras-chave: Oyster culture; Oyster production; European countries; Maryland; Chesapeake Bay; Causes; Perspectives.
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00043/15411/12770.pdf

Dynamics of an estuarine ecosystem: The influence of flow patterns on phytoplankton trends in the Chesapeake Bay
Provedor de dados: 5
Autores: Marshall, Hg; Alden, Rw.
Long term trends in the phytoplankton of the lower Chesapeake Bay were identified using flow corrected and uncorrected data sets, with 22 of 23 significant trends similar under both conditions. The major trends between 1985-1992 were for: 1) reduced phytoplankton concentrations; 2) decreasing numbers of phytoplankton taxa during spring, summer and fall months; and 3) seasonally mixed trends for diatom abundance in waters below the pycnocline, with spring months having decreasing densities, and increasing abundance trends in November and December. The flow patterns had different effects on the trends. Flow diminished the magnitude of the trends for total phytplankton concentrations, so these trends were greater in the flow corrected data. There were mixed...
Tipo: Text
Palavras-chave: Phytoplankton; Chesapeake Bay; Trends; Flow.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20383/18051.pdf

The Certainty of Confronting Uncertainty in the Chesapeake Bay Restoration Effort
Provedor de dados: 31
Autores: Hershner,   Carlton.
Tipo: Journal Article
Palavras-chave: Environmental Restoration; TMDL; Chesapeake Bay; Adaptive Management; Uncertainty; Environmental Economics and Policy; Resource /Energy Economics and Policy; Q00; Q01; Q20; Q28.
Ano: 2011
URL: http://purl.umn.edu/117401

Nutrient Trading, the Flush Tax, and Maryland's Nitrogen Emissions to the Chesapeake Bay
Provedor de dados: 31
Autores: Hanson,   James C.; McConnell,   Kenneth E.
We investigate nutrient trading for point and non-point sources for the Bay Restoration Fund in Maryland. We demonstrate how to use the proceeds from the tax revenue to mimic trading high-cost upgrades of sewage treatment plants for low-cost winter cover crops. Under an optimistic assumption about costs for non-point sources, we calculate that abatement could be increased by more than 50%, while in a pessimistic scenario, abatement could be increased by 2%. We also explore the role of uncertainty in determining the appropriate trading ratio between point and non-point sources of pollution, showing that the higher uncertainty associated with non-point sources should induce a lower trading ratio.
Tipo: Working or Discussion Paper
Palavras-chave: Chesapeake Bay; Cover crops; Nitrogen abatement; Nutrient trading; Sewage treatment plants; Trading ratios; Water pollution; Environmental Economics and Policy.
Ano: 2007
URL: http://purl.umn.edu/7343

Allocating Pollution Load Reductions between States Fairly, Efficiently and Successfully
Provedor de dados: 31
Autores: Kwasnica,   Anthony M.
Tipo: Journal Article
Palavras-chave: Pollution; Politics; Chesapeake Bay; Transboundary Agreements; Environmental Economics and Policy; Resource /Energy Economics and Policy; Q58.
Ano: 2011
URL: http://purl.umn.edu/117407

Environmental Services Programs for the Chesapeake Bay
Provedor de dados: 31
Autores: Shabman,   Leonard A.; Rose,   Bob; Stephenson,   Kurt.
Tipo: Journal Article
Palavras-chave: Ecosystem Services; Payment for Ecosystem Services; Water Quality; Chesapeake Bay; Environmental Economics and Policy; Resource /Energy Economics and Policy; Q25; Q28; Q53; Q57.
Ano: 2011
URL: http://purl.umn.edu/117405

Impact of Environmental Policies on the Adoption of Animal Waste Management Practices in the Chesapeake Bay Watershed
Provedor de dados: 31
Autores: Savage,   Jeff; Ribaudo,   Marc.
We use data from the ERS-NASS ARMS surveys to compare the use of best management practices on poultry and livestock farms inside the watershed and outside the watershed. Animal operations within the Chesapeake Bay States were found to be adopting some important manure management practices at a greater rate than operations outside the watershed. Adoption was taking place before the implementation of the TMDL, indicating that farmers may have been acting in response to building public pressure to reduce pollution.
Tipo: Presentation
Palavras-chave: Chesapeake Bay; Confined animal operation; Water quality; Environmental Economics and Policy; Livestock Production/Industries.
Ano: 2012
URL: http://purl.umn.edu/123246

Technical Documentation of the Regional Manure Management Model for the Chesapeake Bay Watershed
Provedor de dados: 31
Autores: Aillery,   Marcel P.; Gollehon,   Noel R.; Breneman,   Vincent E.
The Regional Manure Management Model, developed for the ERS project on "Manure Management for Improved Water Quality," is used to evaluate the cost and feasibility of manure land application as a manure management strategy at the regional level. This model is a nonlinear mathematical programming model of animal manure-nutrient production and distribution applied to the Chesapeake Bay watershed. The model is designed to assess regional costs of manure management, transport, and land application in the Chesapeake Bay watershed, given the existing structure of the animal industry and manure-storage technologies currently in use. Manure-nutrient production is allocated within the basin to minimize costs to the animal sector, subject to land availability and...
Tipo: Report
Palavras-chave: Technical documentation; Regional analysis; Chesapeake Bay; Animal waste; Manure management; Nutrient management plan; Manure land application; Manure transport; Cost minimization; Optimization model; Environmental Economics and Policy; Livestock Production/Industries.
Ano: 2005
URL: http://purl.umn.edu/33570

Spatial Considerations in Air- and Water-Quality Tradeoffs for Animal Agriculture
Provedor de dados: 31
Autores: Gollehon,   Noel R.; Aillery,   Marcel P.
Total and average per ton costs of land-applying manure demonstrate the importance of spatial factors on the potential effect of policy limits for water and air emissions.  Per ton costs vary with the need to transport greater distances for land application, reflecting the spatial distribution of cropland and animal production.  Costs are estimated with a regional modeling framework, applied to the Chesapeake Bay watershed that integrates GIS-based spatial data within an optimization framework.
Tipo: Conference Paper or Presentation
Palavras-chave: Regional optimization; Geographic information systems; Spatial data; Manure management; Confined animals; Nutrient policies; Water quality; Air quality; Chesapeake Bay; Environmental Economics and Policy; Livestock Production/Industries.
Ano: 2007
URL: http://purl.umn.edu/9848

Beyond Water-Quality Regulations for CAFOs? Manure Management Costs to Meet Air-Quality Objectives
Provedor de dados: 31
Autores: Aillery,   Marcel P.; Gollehon,   Noel R.
Federal policy on manure management has focused on water-quality protection.  However, animal agriculture is an important source of ammonia-nitrogen and other air emissions, increasing attention on air-quality concerns.  Policies to address air emissions would influence both the costs of meeting water-quality objectives and environmental tradeoffs.  We consider hypothetical policies at a regional level.
Tipo: Conference Paper or Presentation
Palavras-chave: Manure management; Confined animals; Water quality; Air quality; Regional optimization; Chesapeake Bay; Environmental Economics and Policy.
Ano: 2005
URL: http://purl.umn.edu/19208

The Chesapeake Bay and the Control of NOx Emissions: A Policy Analysis
Provedor de dados: 31
Autores: Krupnick,   Alan J.; McConnell,   Virginia D.; Austin,   David H.; Cannon,   Matthew; Stoessell,   Terrell; Morton,   Brian.
Nitrogen oxide emissions not only affect air quality but have recently been found to be an important source of nitrate pollution in the Chesapeake Bay. This analysis examines the costs, emissions, source specific and location-specific allocations of NOx emissions reductions and the ancillary ozone related health benefits under a range of policy scenarios. The paper includes analysis of three separate policies. The first is a detailed analysis of the effect on nitrate loadings to the Bay of command and control policies specified in the Clean Air Act and as part of the OTAG process. The second is a comparison of alternative scenarios for reducing NOx emissions that meet nitrate loading goals, with or without concern for reducing ozone concentrations and the...
Tipo: Working or Discussion Paper
Palavras-chave: Chesapeake Bay; Cost effectiveness; Air pollution; Environmental Economics and Policy; Q20; Q25; Q28.
Ano: 1998
URL: http://purl.umn.edu/10576

Simulated Trading for Maryland's Nitrogen Loadings in the Chesapeake Bay
Provedor de dados: 31
Autores: Hanson,   James C.; McConnell,   Kenneth E.
We investigate nutrient trading for point and non-point sources for the Bay Restoration Fund in Maryland. We demonstrate how to use the proceeds from the tax revenue to mimic a market by trading high-cost upgrades of sewage treatment plants for low-cost winter cover crops. Under an optimistic assumption about costs for non-point sources and naïve assumptions about the lag from planting cover crops to changes in nitrogen load, we calculate that 100 percent of abatement could be achieved at 56 percent of total costs, while in a pessimistic scenario, 100 percent of abatement could be could be achieved at 83 percent of total costs.
Tipo: Journal Article
Palavras-chave: Chesapeake Bay; Cover crops; Nitrogen abatement; Nutrient trading; Sewage treatment plants; Trading ratios; Water pollution; Environmental Economics and Policy.
Ano: 2008
URL: http://purl.umn.edu/45669

Improving the Efficiency and Effectiveness of Agri-environmental Policies for the Chesapeake Bay
Provedor de dados: 31
Autores: Ribaudo,   Marc; Shortle,   James S.; Blandford,   David; Horan,   Richard D.
Tipo: Journal Article
Palavras-chave: Water Quality; Nonpoint Source Pollution; Policy Instrument; Chesapeake Bay; Environmental Economics and Policy; Resource /Energy Economics and Policy; Q25; Q58.
Ano: 2011
URL: http://purl.umn.edu/117403

A REGIONAL MODELING STRUCTURE FOR ASSESSING MANURE MANAGEMENT POLICIES: APPLICATION TO THE CHESAPEAKE BAY WATERSHED
Provedor de dados: 31
Autores: Aillery,   Marcel P.; Gollehon,   Noel R.; Ribaudo,   Marc; Breneman,   Vincent E.
A modeling framework addresses manure management policies within the Chesapeake Bay watershed.  Policy focus is on manure-land application at agronomic rates, as proposed under the EPA/USDA Unified Strategy.  Manure-nutrient flows are assessed subject to assimilative capacity of farmland.  National data bases and GIS coverages facilitate model transferability to other watersheds.
Tipo: Conference Paper or Presentation
Palavras-chave: Manure management; Confined livestock operations; Regional optimization; Chesapeake Bay; Environmental Economics and Policy; Livestock Production/Industries.
Ano: 2001
URL: http://purl.umn.edu/20530