Recent Submissions

  • Synthesis of summer flounder habitat parameters

    Able, Kenneth W.; Kaiser, Susan C. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1994)
    The summer flounder, Paralichthys dentatus, is overexploited and is currently at very low levels of abundance. This is reflected in the compressed age structure of the population and the low catches in both commercial and recreational fisheries. Declining habitat quantity and quality may be contributing to these declines, however we lack a thorough understanding of the role of habitats in the population dynamics of this species. Stock structure is unresolved and current interpretations, depending on the technique and study area, suggest that there may be two or three spawning populations. If so, these stocks may have differing habitat requirements. In response to this lack of knowledge, this document summarizes and synthesizes the available information on summer flounder habitat in all life history stages (eggs, larvae, juveniles and adults) and identifies areas where further research is needed.Several levels of investigation were conducted in order to produce this document. First, an extensive search for summer flounder habitat information was made, whichincluded both the primary and gray literature as well as unanalyzed data. Second, state and federal fisheries biologists and resource managers in all states within theprimary range of summer flounder (Massachusetts to Florida) were interviewed along with a number of fish ecologists and summer flounder experts from the academic and private sectors. Finally, information from all sources was analyzed and synthesized to form a coherent overview.This document first presents an overview of the economic importance and current status of summer flounder (Chapter 1). It then summarizes our present state of knowledge of summer flounder distribution, life history patterns and stock identification (Chapter 2). This is followed by a synopsis of habitat requirements during each life history stage. For convenience, this is presented by general habitat as offshore eggs (Chapter 3), offshore larvae (Chapter 4), estuarine larvae (Chapter 5), estuarinejuveniles (Chapter 6), offshore juveniles (Chapter 7) and estuarine and offshore adults (Chapter 8). In several instances, previously undigested data sets are analyzed toprovide more detailed information, especially for estuarine juveniles. The information is then discussed in terms of its relevance to resource managers (Chapter 9).
  • Technology and success in restoration, creation, and enhancement of Spartina afferniflora marshes in the United States. Vol. 1: Executive Summary and Annotated Bibliography

    Matthews, Geoffrey A.; Minello , Thomas J. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1994)
    Extensive losses of coastal wetlands in the United States caused by sea-level rise, land subsidence, erosion, and coastal development have increased hterest in the creation of salt marshes within estuaries. Smooth cordgrass Spartina altemiflora is the species utilized most for salt marsh creation and restoration throughout the Atlantic and Gulf coasts of the U.S., while S. foliosa and Salicomia virginica are often used in California. Salt marshes have many valuable functions such as protecting shorelines from erosion, stabilizing deposits of dredged material, dampening flood effects, trapping water-born sediments, serving as nutrient reservoirs, acting as tertiary watertreatment systems to rid coastal waters of contaminants, serving as nurseries for many juvenile fish and shellfish species, and serving as habitat for various wildlife species(Kusler and Kentula 1989). The establishment of vegetation in itself is generally sufficient to provide the functions of erosion control, substrate stabilization, and sediment trapping. The development of other salt marsh functions, however, is more difficult to assess. For example, natural estuarine salt marshes support a wide variety of fish and shellfish, and the abundance of coastal marshes has been correlated with fisheries landings (Turner 1977, Boesch and Turner 1984). Marshes function for aquatic species by providing breeding areas, refuges from predation, and rich feeding grounds (Zimmerman and Minello 1984, Boesch and Turner 1984, Kneib 1984, 1987, Minello and Zimmerman 1991). However, the relative value of created marshes versus that of natural marshes for estuarine animals has been questioned (Carnmen 1976, Race and Christie 1982, Broome 1989, Pacific Estuarine Research Laboratory 1990, LaSalle et al. 1991, Minello and Zimmerman 1992, Zedler 1993). Restoration of all salt marsh functions is necessary to prevent habitat creation and restoration activities from having a negative impact on coastal ecosystems.
  • Bibliography of synthesis documents on selected coastal ocean topics

    Collins, Elaine V.; Woods, Maureen; Sheifer, Isobel; Beattie, Janice (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1994)
    This compilation of references to works which synthesize information on coastal topics is intended to be useful to resource managers in decision making processes. However, the utility must be understand in terms of its limited coverage. The bibliography is not inclusive of all the published materials on the topics selected.Coverage is clearly defined in the following paragraph.The time span of the bibliography is limited to references that were published from I983 to 1993, except for a last-minute addition of a few 1994 publications. All searches were done in mid- to late-1993. The bibliography was compiled from searches done on the following DIALOG electronic databases: Aquatic Sciences and Fisheries Abstracts, BlOSlS Previews, Dissertation Abstracts Online, Life Sciences Collection, NTlS (National Technical lnformation Service), Oceanic Abstracts, Pollution Abstracts, SciSearch, and Water Resources Abstracts. Inaddition, two NOAA electronic datases were searched: the NOAA Library and lnformation Catalog and the NOAA Sea Grant Depository Database.Synthesis of information is not an ubiquitous term used in database development. In order to locate syntheses of required coastal topics, 89 search terms were used in combinations which required 10 searches from each file. From the nearly 6,000 citations which resulted from the electronic searches, the most appropriate were selected to produce this bibliography. The document was edited and indexed using Wordperfect software. When available, an abstract has been included. Every abstract was edited.The bibliography is subdivided into four main topics or sections: ecosystems, coastal water body conditions, natural disasters, and resource management. In theecosystems section, emphasis is placed on organisms in their environment on the major coastlines of the U.S. In the second section, coastal water body conditions, the environment itself is emphasized. References were found for the Alaskan coast, but none were found for Hawaii. The third section, on natural disasters, emphasizes environmental impacts resulting from natural phenomena. Guidelines, planning and management reports, modelling documents, strategic and restoration plans, and environmental economics related to sustainability are included in the fourth section, resource management. Author, geographic, and subject indices indices are provided.The authors would like to thank Victor Omelczenko and Terry Seldon of the NOAA Sea Grant Office for access to and training on the NOAA Sea Grant Depository Database. We are grateful also to Dorothy Anderson, Philip Keavey, and Elizabeth Petersen who reviewed the draft document.
  • Marine eutrophication review. Part 1: Quantifying the effects of nitrogen enrichment on phytoplankton in coastal ecosystems; Part 2: Bibliography with abstracts

    Hinga, Kenneth R.; Heon, Jeeseon; Lewis , Noelle F. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1995)
    Professionals who are responsible for coastal environmental and natural resource planning and management have a need to become conversant with new concepts designed to provide quantitative measures of the environmental benefits of natural resources. These amenities range from beaches to wetlands to clean water and other assets that normally are not bought and sold in everyday markets.At all levels of government — from federal agencies to townships and counties — decisionmakers are being asked to account for the costs and benefits of proposed actions. To non-specialists, the tools of professional economists are often poorly understood and sometimes inappropriatefor the problem at hand. This handbook is intended to bridge this gap.The most widely used organizing tool for dealing with natural and environmental resource choices is benefit-cost analysis — it offers a convenient way to carefully identify and array, quantitatively if possible, the major costs, benefits, and consequences of a proposed policy or regulation.The major strength of benefit-cost analysis is not necessarily the predicted outcome, which depends upon assumptions and techniques, but the process itself, which forces an approach to decision-making that is based largely on rigorous and quantitative reasoning.However, a major shortfall of benefit-cost analysis has been the difficulty of quantifying both benefits and costs of actions that impact environmental assets not normally, nor even regularly, bought and sold in markets. Failure to account for these assets, to omit them from the benefit-costequation, could seriously bias decisionmaking, often to the detriment of the environment. Economists and other social scientists have put a great deal of effort into addressing this shortcoming by developing techniques to quantify these non-market benefits.The major focus of this handbook is on introducing and illustrating concepts of environmental valuation, among them Travel Cost models and Contingent Valuation. These concepts, combined with advances in natural sciences that allow us to better understand how changes in the naturalenvironment influence human behavior, aim to address some of the more serious shortcomings in the application of economic analysis to natural resource and environmental management and policy analysis.Because the handbook is intended for non-economists, it addresses basic concepts of economic value such as willingness-to-pay and other tools often used in decision making such as costeffectiveness analysis, economic impact analysis, and sustainable development. A number of regionally oriented case studies are included to illustrate the practical application of these concepts and techniques.
  • Economic valuation of natural resources: a handbook for coastal resource policymakers

    Lipton, Douglas W.; Wellman, Katherine; Sheifer, Isobel; Weiher, Rodney (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1995)
    Professionals who are responsible for coastal environmental and natural resource planning and management have a need to become conversant with new concepts designed to provide quantitative measures of the environmental benefits of natural resources. These amenities range from beaches to wetlands to clean water and other assets that normally are not bought and sold in everyday markets.At all levels of government — from federal agencies to townships and counties — decisionmakers are being asked to account for the costs and benefits of proposed actions. To non-specialists, the tools of professional economists are often poorly understood and sometimes inappropriatefor the problem at hand. This handbook is intended to bridge this gap.The most widely used organizing tool for dealing with natural and environmental resource choices is benefit-cost analysis — it offers a convenient way to carefully identify and array, quantitatively if possible, the major costs, benefits, and consequences of a proposed policy or regulation.The major strength of benefit-cost analysis is not necessarily the predicted outcome, which depends upon assumptions and techniques, but the process itself, which forces an approach to decision-making that is based largely on rigorous and quantitative reasoning.However, a major shortfall of benefit-cost analysis has been the difficulty of quantifying both benefits and costs of actions that impact environmental assets not normally, nor even regularly, bought and sold in markets. Failure to account for these assets, to omit them from the benefit-costequation, could seriously bias decisionmaking, often to the detriment of the environment. Economists and other social scientists have put a great deal of effort into addressing this shortcoming by developing techniques to quantify these non-market benefits.The major focus of this handbook is on introducing and illustrating concepts of environmental valuation, among them Travel Cost models and Contingent Valuation. These concepts, combined with advances in natural sciences that allow us to better understand how changes in the naturalenvironment influence human behavior, aim to address some of the more serious shortcomings in the application of economic analysis to natural resource and environmental management and policy analysis.Because the handbook is intended for non-economists, it addresses basic concepts of economic value such as willingness-to-pay and other tools often used in decision making such as costeffectiveness analysis, economic impact analysis, and sustainable development. A number of regionally oriented case studies are included to illustrate the practical application of these concepts and techniques.
  • Methodologies and mechanisms for management of cumulative coastal environmental impacts. Part I: Synthesis, with annotated bibliography; Part II: Development and application of a cumulative impacts assessment protocol

    Vestal , Barbara; Rieser, Alison (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1995)
    What Are ~umulat iveE ffects?Coastal managers now recognize that many of the most serious resource degradation problems have built up gradually as the combined outcome of numerous actions and choices which alone may have had relatively minor impacts. For example, alteration of essential habitat throughwetland loss, degradation of water quality from nonpoint source pollution, and changes in salinity of estuarine waters from water diversion projects can be attributed to numerous small actions and choices. These incremental losses have broad spatial and temporal dimensions,resulting in the gradual alteration of structure and functioning of biophysical systems. In the environmental management field, the term "cumulative effects" is generally used to describe this phenomenon of changes in the environment that result from numerous, small-scale alterations.
  • Forestry Impacts on Freshwater Habitat of Anadromous Salmonids in the Pacific Northwest and Alaska: requirements for protection and restoration

    Murphy, Michael L. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1995)
    This synthesis presents a science overview of the major forest management Issues involved in the recovery of anadromous salmonids affected by timber harvest in the Pacific Northwest and Alaska. The issues involve the components of ecosystem-based watershed management and howbest to implement them, including how to: Design buffer zones to protect fish habitat while enabling economic timber production; Implement effective Best Management Practices (BMPs) to prevent nonpoint-source pollution;Develop watershed-level procedures across property boundaries to prevent cumulative impacts; Develop restoration procedures to contribute to recovery of ecosystem processes; and Enlist support of private landowners in watershed planning, protection, and restoration.Buffer zones, BMPs, cumulative impact prevention, and restoration are essential elements of what must be a comprehensive approach to habitat protection and restoration applied at the watershed level within a larger context of resource concerns in the river basin, species status under the Endangered Species Act (ESA), and regional environmental and economic issues (Fig. ES. 1).This synthesis 1) reviews salmonid habitat requirements and potential effects of logging; 2) describes the technical foundation of forest practices and restoration; 3) analyzes current federal and non-federal forest practices; and 4) recommends required elements of comprehensive watershed management for recovery of anadromous salmonids.
  • Watershed restoration: a guide for citizen involvement in California.

    Kier (William M.) Associates (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1995)
    There is nothing mysterious about how coastal rivers, their estuaries, and their relationship with the sea all work to satisfy many of our greatest needs, including drinkable water, fish and shellfish, and soils essential for sustaining the production of food and fiber. Nor are the methods that have proved successful in the protection andrestoration of watershed health difficult to understand. It is difficult, however, to imagine how we are to survive without healthy watersheds. Each watershed alongCalifornia’s coast shows signs of increasing abuse from road construction and maintenance, livestock grazing, residential development, timber harvesting, and a dozen other human activities. In some cases whole streams have simply been wiped away.This document has been created to guide and support every person in the community, from homemaker to elected official, who wants her or his watershed to provide cleanwater, harvestable fish resources and other proof that life in the watershed cannot only be maintained but also enjoyed. It is based on years of experience with watershedprotection and restoration in California. If citizen involvement is to be effective, it must draw not only on scientific knowledge but also on an understanding of how totranslate individual views into commitments and capable group action.This guide briefly reviews the condition of California’s coastal watersheds, identifies the kinds of concerns that have led citizens to successful watershed protection efforts, explains why citizen, in addition to government, effort is essential for watershed protection and restoration to succeed, and puts in the reader’s hands both the technical and organizational “tools of the trade” in the hope that those who use this guide will be encouraged to join in efforts to make their watershed serve this and future generations better.
  • Atmospheric nutrient input to coastal areas: reducing the uncertainties

    Valigura, Richard A.; Luke, Winston T.; Artz, Richard S.; Hicks, Bruce B. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1996)
    A significant fraction of the total nitrogen entering coastal and estuarine ecosystems along the eastern U.S. coast arises from atmospheric deposition; however, the exact role of atmospherically derived nitrogen in the decline of the health of coastal, estuarine, and inland waters is still uncertain. From the perspective of coastal ecosystem eutrophication, nitrogen compounds from the air, along with nitrogen from sewage, industrial effluent, and fertilizers, become a source of nutrients to the receiving ecosystem. Eutrophication, however, is only one of the detrimental impacts of the emission of nitrogen containing compounds to the atmosphere. Other adverse effects include the production of tropospheric ozone, acid deposition, and decreased visibility (photochemical smog).Assessments of the coastal eutrophication problem indicate that the atmospheric deposition loading is most important in the region extending from Albemarle/Parnlico Sounds to the Gulf of Maine; however, these assessments are based on model outputs supported by a meager amount of actual data. The data shortage is severe. The National Research Council specifically mentions the atmospheric role in its recent publication for the Committee on Environmental and NaturalResources, Priorities for Coastal Ecosystem Science (1994). It states that, "Problems associated with changes in the quantity and quality of inputs to coastal environments from runoff and atmospheric deposition are particularly important [to coastal ecosystem integrity]. These includenutrient loading from agriculture and fossil fuel combustion, habitat losses from eutrophication, widespread contamination by toxic materials, changes in riverborne sediment, and alteration of coastal hydrodynamics. "
  • Harmful algal blooms in coastal waters: options for prevention, control and mitigation

    Boesch, Donald F.; Anderson, Donald M.; Horner, Rita A.; Shumway, Sandra E.; Tester, Patricia A.; Whitledge, Terry E. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1997)
    This report is the product of a panel of experts in the science of blooms of unicellular marine algae which can cause mass mortalities in a variety of marine organisms and cause illness and even death in humans who consume contaminated seafood. These phenomena are collectively termed harmful algal blooms or HABs for short. As a counterpart to recent assessments of the priorities forscientific research to understand the causes and behavior of HABs, this assessment addressed the management options for reducing their incidence and extent (prevention), actions that can quell or contain blooms (control), and steps to reduce the losses of resources or economic values and minimize human health risks (mitigation).This assessment is limited to an appraisal of scientific understanding, but also reflects consideration of information and perspectives provided by regional experts, agency managers and user constituencies during three regional meetings. The panel convened these meetings during the latter half of 1996 to solicit information and opinions from scientific experts, agency managers and user constituencies in Texas, Washington, and Florida. The panel's assessment limited its attention to those HABs that result in neurotoxic shellfish poisoning, paralytic shellfish poisoning, brown tides, amnesic shellfish poisoning, and aquaculture fish kills. This covers most, but certainly not all, HAB problems in the U.S.
  • Change in Pacific Northwest coastal ecosystems. Proceedings of the Pacific Northwest Coastal Ecosystems Regional Study Workshop, August 73-14, 1996, Troutdale, Oregon

    McMurray, Gregory R.; Bailey, Robert J. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1998)
    Over the past one hundred and fifty years, the landscape and ecosystems of the Pacific Northwest coastal region, already subject to many variable natural forces, have been profoundly affected by human activities. In virtually every coastal watershed from the Strait of Juan de Fuca to CapeMendocino, settlement, exploitation and development of resou?-ces have altered natural ecosystems. Vast, complex forests that once covered the region have been largely replaced by tree plantations or converted to non-forest conditions. Narrow coastal valleys, once filled withwetlands and braided streams that tempered storm runoff and provided salmon habitat, were drained, filled, or have otherwise been altered to create land for agriculture and other uses. Tideflats and saltmarshes in both large and small estuaries were filled for industrial, commercial,and other urban uses. Many estuaries, including that of the Columbia River, have been channeled, deepened, and jettied to provide for safe, reliable navigation. The prodigious rainfall in the region, once buffered by dense vegetation and complex river and stream habitat, now surges down sirfiplified stream channels laden with increased burdens of sediment and debris. Although these and many other changes have occurred incrementally over time and in widely separated areas, their sum can now be seen to have significantly affected the natural productivity of theregion and, as a consequence, changed the economic structure of its human communities. This activity has taken place in a region already shaped by many interacting and dynamic natural forces. Large-scale ocean circulation patterns, which vary over long time periods, determine the strength and location of currents along the coast, and thus affect conditions in the nearshoreocean and estuaries throughout the region. Periodic seasonal differences in the weather and ocean act on shorter time scales; winters are typically wet with storms from the southwest while summers tend to be dry with winds from the northwest. Some phenomena are episodic, such asEl Nifio events, which alter weather, marine habitats, and the distribution and survival of marine organisms. Other oceanic and atmospheric changes operate more slowly; over time scales of decades, centuries, and longer. Episodic geologic events also punctuate the region, such asvolcanic eruptions that discharge widespread blankets of ash, frequent minor earthquakes, and major subduction zone earthquakes each 300 to 500 years that release accumulated tectonic strain, dropping stretches of ocean shoreline, inundating estuaries and coastal valleys, and triggering landslides that reshape stream profiles. While these many natural processes have altered, sometimes dramatically, the Pacific Northwest coastal region, these same processes haveformed productive marine and coastal ecosystems, and many of the species in these systems have adapted to the variable environmental conditions of the region to ensure their long-term survival.
  • Guidelines for the conservation and restoration of seagrasses in the United States and adjacent waters

    Fonseca, Mark S.; Kenworthy, W. Judson; Thayer, Gordon W. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1998)
    Seagrass ecosystems are protected under the federal "no-net-loss" policy for wetlands and form one of the mostproductive plant communities on the planet, performing important ecological functions. Seagrass beds have been recognized as a valuable resource critical to the health and function of coastal waters. Greater awareness and public education, however, is essential for conservation of this resource. Tremendous losses of this habitat have occurred as a result of development within the coastal zone. Disturbances usually kill seagrasses rapidly, and recovery is often comparatively slow. Mitigation to compensate for destruction of existing habitat usually follows when the agent of loss and responsible party are known. Compensation assumes that ecosystems can be made to order and, in essence, trades existing functional habitatfor the promise of replacement habitat. While ~lant ingse agrass is not technically complex, there is no easy way to meet the goal of maintaining or increasing seagrass acreage. Rather, the entire process of planning, planting and monitoring requires attention to detail and does notlend itself to oversimplification.
  • Bering Sea FOCI Final Report

    Macklin, S. A. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1998)
    To develop an understanding of stock structure and recruitment variation in Bering Sea pollock, the Coastal Ocean Program of the National Oceanic and Atmospheric Administration (NOAA) funded an 7-year (1991-1997),interdisciplinary project named Bering Sea Fisheries-Oceanography Coordinated Investigations (BS FOCI; Schumacher and Kendall, 1995) for which NOAA and academic researchers were selected through a competitive process(Macklin, this report). The project goals, based on recommendations from an international symposium on pollock (Aron and Balsiger, 1989) were to (1) determine stock structure in the Bering Sea and its potential relationshipto physical oceanography, and (2) examine recruitment processes in the eastern Bering Sea. Both of these have direct implication to management. An integrated set of field, laboratory, and modeling studies were establishedto accomplish these goals. To address the first goal, project objectives were to establish details of oceanic circulation relevant to larval dispersal and separation of stocks, and determine if unique chemical or genetic indicators existed for different stocks. The recruitment component of BS FOCI, addressing the second goal, focused on understanding causes of variable mortality of pollock larvae in the different habitats of the eastern Bering Sea.The emphasis of recruitment studies was to determine the dominant physical oceanographic features (turbulence, temperature, and transport) that could influence survival of pollock larvae, and investigate factors controllingfood production for the larvae. A later component contrasted juvenile habitat in three hydrographic regimes around the Pribilof Islands (Brodeur, this report).
  • Nutrient enhanced coastal ocean productivity in the north Gulf of Mexico: understanding the effects of nutrients on a coastal ecosystem

    Wiseman, Jr., William J.; Rabalais, Nancy N.; Dagg, Michael J.; Whitledge, Terry E. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
    The continental shelf adjacent to the Mississippi River is a highly productive system, often referred to as the fertile fisheries crescent. This productivity is attributed to the effects of the river, especially nutrient delivery. In the later decades of the 2oth century, though, changes in the system were becoming evident. Nutrient loads were seen to be increasing and reports of hypoxia were becoming more frequent.During most recent summers, a broad area (up to 20,000 krn2) of near bottom, inner shelf waters immediately west of the Mississippi River delta becomes hypoxic (dissolved oxygen concentrations less than 2 mgll). In 1990, the Coastal Ocean Program of the National Oceanic and Atmospheric Administration initiated the Nutrient Enhanced Coastal Ocean Productivity (NECOP) study of this area to test the hypothesis that anthropogenic nutrient addition to the coastal ocean has contributed to coastal eutrophication with a significant impact on water quality. Three major goals of the study were to determine the degree to which coastal productivity in the region is enhanced by terrestrial nutrient input, to determine the impact of enhanced productivity on water quality, and to determine the fate of fixed carbon and its impact on living marineresources. The study involved 49 federal and academic scientists from 14 institutions and cost $9.7 million. Field work proceeded from 1990 through 1993 and analysis through 1996, although some analyses continue to this day.The Mississippi River system delivers, on average, 19,000 m3/s of water to the northern Gulf of Mexico. The major flood of the river system occurs in spring following snow melt in the upper drainage basin. This water reaches the Gulf of Mexico through the Mississippi River birdfootdelta and through the delta of the Atchafalaya River. Much of this water flows westward along the coast as a highly stratified coastal current, the Louisiana Coastal Current, isolated from the bottom by a strong halocline and from mid-shelf waters by a strong salinity front. This stratification maintains dissolved and particulate matter from the rivers, as well as recycled material, in a well-defined flow over the inner shelf. It also inhibits the downward mixing of oxygenated surface waters from the surface layer to the near bottom waters. This highlystratified flow is readily identifiable by its surface turbidity, as it carries much of the fine material delivered with the river discharge and resuspended by nearshore wave activity. A second significant contribution to the turbidity of the surface waters is due to phytoplankton in these waters. This turbidity reduces the solar radiation penetrating to depth through the watercolumn. These two aspects of the coastal current, isolation of the inner shelf surface waters and maintenance of a turbid surface layer, precondition the waters for the development of near bottom summer hypoxia.
  • Characterization of Hypoxia: Topic I Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico

    Rabalais, Nancy N.; Turner, R. Eugene; Justic, Dubravko; Dortch, Quay; Wiseman, Jr., William J. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
    Nutrient overenrichment from human activities is one of the major stresses affecting coastal ecosystems. There is increasing concern in many areas around the world that an oversupply of nutrients from multiple sources is having pervasive ecological effects on shallow coastal and estuarine areas. These effects include reduced light penetration, loss of aquatic habitat, harmfid algal blooms, a decrease in dissolved oxygen (or hypoxia), and impacts on living resources. The largest zone of oxygen-depleted coastal waters in the United States, and the entire western Atlantic Ocean, is found in the northern Gulf of Mexico on the Louisiana-Texas continental shelf. This zone is influenced by the freshwater discharge and nutrient flux of the Mississippi River system.This report describes the seasonal, interannual, and long-term variability in hypoxia in the northern Gulf of Mexico and its relationship to nutrient loading. It also documents the relative roles of natural and human-induced factors in determining the size and duration of the hypoxic zone.
  • Ecological and economic consequences of hypoxia: Topic 2 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico

    Diaz, Robert J.; Solow, Andrew (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
    In this report we have attempted to evaluate the ecological and economic consequences of hypoxia in the northern Gulf of Mexico. Although our initial approach was to rely on published accounts, we quickly realized that the body of published literature deahng with hypoxia was limited,and we would have to conduct our own exploratory analysis of existing Gulf data, or rely on published accounts from other systems to infer possible or potential effects of hypoxia.For the economic analysis, we developed a conceptual model of how hypoxia-related impacts could affect fisheries. Our model included both supply and demand components. The supplymodel had two components: (1) a physical production function for fish or shrimp, and (2) the cost of fishing. If hypoxia causes the cost of a unit of fishing effort to change, then this will result in a shift in supply. The demand model considered how hypoxia might affect the quality of landed fish or shrimp. In particular, the market value per pound is lower for small shrimp thanfor large shrimp.Given the limitations of the ecological assessment, the shallow continental shelf area affected by hypoxia does show signs of hypoxia-related stress. While current ecological conditions are a response to a variety of stressors, the effects of hypoxia are most obvious in the benthos that experience mortality, elimination of larger long-lived species, and a shifting of productivity to nonhypoxic periods (energy pulsing). What is not known is whether hypoxia leads to higher productivity during productive periods, or simply to a reduction of productivity during oxygen-stressed periods.The economic assessment based on fisheries data, however, failed to detect effects attributable to hypoxia. Overall, fisheries landings statistics for at least the last few decades have been relatively constant. The failure to identify clear hypoxic effects in the fisheries statistics does not necessarily mean that they are absent. There are several possibilities: (1) hypoxic effects are small relative to the overall variability in the data sets evaluated; (2) the data and the power of the analyses are not adequate; and (3) currently there are no hypoxic effects on fisheries.Lack of identified hypoxic effects in available fisheries data does not imply that effects would not occur should conditions worsen. Experience with other hypoxic zones around the globe shows that both ecological and fisheries effects become progressively more severe as hypoxia increases. Several large systems around the globe have suffered serious ecological and economic consequencesfrom seasonal summertime hypoxia; most notable are the Kattegat and Black Sea. The consequences range from localized loss of catch and recruitment failure to complete system-wide loss of fishery species. If experiences in other systems are applicable to the Gulf of Mexico, thenin the face of worsening hypoxic conditions, at some point fisheries and other species will decline, perhaps precipitously.
  • Flux and sources of nutrients in the Mississippi-Atchafalaya River Basin: Topic 3 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico.

    Goolsby, Donald A.; Battaglin, William A.; Lawrence , Gregory B.; Artz, Richard S.; Aulenbach, Brent T.; Hooper , Richard P.; Keeney, Dennis R.; Stensland, Gary J. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
    Ths report addresses the following two questions:1) What are the loads (flux) of nutrients transported from the Mississippi-Atchafalaya River Basin to the Gulf of Mexico, and where do they come from within the basin?2) What is the relative importance of specific human activities, such as agriculture, point-source discharges, and atmospheric deposition in contributing to these loads?These questions were addressed by first estimating the flux of nutrients from the Mississippi-Atchafalaya River Basin and about 50 interior basins in the Mississippi River system using measured historical streamflow and water quality data. Annual nutrient inputs and outputs to each basin were estimated using data from the National Agricultural Statistics Service, National Atmospheric Deposition Program, and point-source data provided by the USEPA. Next, a nitrogen mass balance was developed using agricultural statistics, estimates of nutrient cycling in agricultural systems, and a geographic information system. Finally, multiple regression models were developed to estimate the relative contributions of the major input sources to the flux of nitrogen and phosphorus to the Gulfof Mexico.
  • Effects of reducing nutrient loads to surface waters within the Mississippi River Basin and the Gulf of Mexico: Topic 4 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico

    Brezonik, Patrick L.; Bierman, Jr., Victor J.; Alexander , Richard; Anderson, James; Barko, John; Dortch, Mark; Hatch, Lorin; Hitchcock , Gary L.; Keeney, Dennis; Mulla, David; et al. (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
    The overall goal of this assessment was to evaluate the effects of nutrient-source reductions that may be implemented in the Mississippi River Basin (MRB) to reduce the problem of low oxygen conditions (hypoxia) in the nearshore Gulf of Mexico. Such source reductions would affect the quality of surface waters—streams, rivers, and reservoirs—in the drainage basin itself, as well as nearshore Gulf waters. The task group’s work was divided into addressing the effects of nutrient-source reductions on: (1) surface waters in the MRB and (2) hypoxia in the Gulf of Mexico.
  • Reducing nutrient loads, especially nitrate-nitrogen, to surface water, ground water, and the Gulf of Mexico: Topic 5 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico

    Mitsch, William J.; Day, Jr. , John W.; Gilliam, J. Wendell; Groffman, Peter M.; Hey, Donald L.; Randall , Gyles W.; Wang, Naiming (NOAA/National Centers for Coastal Ocean ScienceSilver Spring, MD, 1999)
  • Evaluation of the economic costs and benefits of methods for reducing nutrient loads to the Gulf of Mexico: Topic 6 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico.

    Doering, Otto C.; Diaz-Hermelo, Francisco; Howard, Crystal; Heimlich, Ralph; Hitzhusen, Fred; Kazmierczak, Richard; Lee, John; Libby, Larry; Milon, Walter; Prato, Tony; et al. (NOAA/National Centers for Coastal Ocean ServiceSilver Spring, MD, 1999)
    In this report we analyze the Topic 5 report’s recommendations for reducing nitrogen losses to the Gulf ofMexico (Mitsch et al. 1999). We indicate the relative costs and cost-effectiveness of different control measures, and potential benefits within the Mississippi River Basin. For major nonpoint sources, such as agriculture, we examine both national and basin costs and benefits.Based on the Topic 2 economic analysis (Diaz and Solow 1999), the direct measurable dollar benefits to Gulf fisheries of reducing nitrogen loads from the Mississippi River Basin are very limited at best. Although restoring the ecological communities in the Gulf may be significant over the long term, we do not currently have information available to estimate the benefits of such measures to restore the Gulf’s long-term health. For these reasons, we assume that measures to reduce nitrogen losses to the Gulf will ultimately prove beneficial, and we concentrate on analyzing the cost-effectiveness of alternative reduction strategies.We recognize that important public decisions are seldom made on the basis of strict benefit–cost analysis, especially when complete benefits cannot be estimated. We look at different approaches and different levels of these approaches to identify those that are cost-effective and those that have limited undesirable secondary effects, such as reduced exports, which may result in lost market share.We concentrate on the measures highlighted in the Topic 5 report, and also are guided by the source identification information in the Topic 3 report (Goolsby et al. 1999). Nonpoint sources that are responsible for the bulk of the nitrogen receive most of our attention. We consider restrictions on nitrogen fertilizer levels, and restoration of wetlands and riparian buffers for denitrification. We also examine giving more emphasis to nitrogen control in regions contributing a greater share of the nitrogen load.

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