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1.
Numerous studies have concluded that better use of scientific information could improve the quality of coastal and estuarine environmental management. Approaches for effecting such a change include ecosystem-based, integrated, and adaptive management, but such basic re-orientation of estuarine and coastal management has proved difficult to achieve. Even environmental indicators, seemingly straightforward ways of injecting scientific information into decision making, have achieved broad on-the-ground use in relatively few instances—principally the largest estuary management programs. A conceptual framework useful for examining environmental management systems affecting the five PNCERS (Pacific Northwest coastal Ecosystems Regional Study) estuaries conceives of environmental managers, researchers, and interested and affected parties in the public as interacting through the multi-layered institutional arrangements that currently promote the utilization, management, or protection of coastal and estuarine resources. Considerable variation exists in the approach and effectiveness of the region's environmental management organizations. Interaction between science and management in the region appears to be limited to an extent by high transaction costs; a cultural divide between environmental scientists and environmental managers is perceived by members of both groups who work with the PNCERS estuaries as inhibiting communications between them. Mechanisms that both groups identify as useful for improving the flow of information between science and management are little used, perhaps as a result. The two groups have very different patterns of information dissemination and acquisition, and though both chose agency archives and databases as their top methods for disseminating information, neither group relies much on these vehicles for information they seek. Both residents' and practitioners' perceptions of threats to the PNCERS estuaries show patterns of estuary-to-estuary variation. One theme that emerges is that problems associated with poor land management in adjacent uplands are common to most of these estuaries, potentially providing a sense of commonality through which a more regional approach to estuary management could emerge. A common set of estuarine environmental indicators implemented for all estuaries could help instigate such a regional approach, but resource constraints, especially at the local level, will have to be overcome for that to occur. There is currently substantial lack of common vision among coastal practitioners as to the purpose and desirability of indicators, and relatively little experience or knowledge of their use, particularly at the local level. Use of estuarine science in the management of these estuaries appears to be greatest during periods in which the largest programmatic shifts in environmental management approaches occur, an observation consistent with other studies that have concluded that the use of environmental science in environmental management tends to be episodic.  相似文献   

2.
Hurricane Charley, a category 4 storm on the Safford–Simpson scale, passed over the Peace River, Florida, and its watershed on 13 August 2004 causing widespread hypoxia. An electrofishing study investigating the abundance of the euryhaline Centropomus undecimalis (common snook) began in the freshwater portions of the Peace River 3 months after the storm (November 2004) and included diet sampling. Samples were taken seasonally up to August 2006. Changes in the prey assemblages of C. undecimalis determined through multivariate analyses (e.g., nonmetric multidimensional scaling) were used as a proxy to estimate the recovery of riverine fauna. The initial posthurricane prey assemblages were dominated by species well adapted to low dissolved oxygen, namely Gambusia holbrooki and Hoplosternum littorale. A significant long-term serial change in assemblage structure occurred as the abundance of G. holbrooki and H. littorale decreased and other river fauna such as Procambarus spp. and ictalurid catfish increased. Assemblages were presumed as recovering 1 year after hurricane landfall, a posthurricane recovery period that is an order of magnitude longer than those reported for estuarine fish assemblages. The approach of using stomachs as sampling tools detected changes at the assemblage level that included an armored catfish species (e.g., H. littorale) and cryptic invertebrate species (e.g., Procambarus spp.) that went unnoticed in a study using standard electrofishing methods. Although sampling the diet of C. undecimalis was useful in detecting assemblage-level changes, other metrics—such as changes in health, sex ratio, relative abundance, and juvenile year-class strength of fishes and invertebrates collected by traditional fishing methods—are needed to fully evaluate the effects of the hurricane. Nonetheless, this study demonstrates that diet studies can supplement standard fishery gear to create a more comprehensive sampling strategy for aquatic fauna.  相似文献   

3.
Hurricane Charley, a category 4 storm, passed directly over the Charlotte Harbor estuary and Peace River watershed on August 13, 2004. Following the storm's passage, dissolved oxygen in the Peace River fell below 1 mg l−1 and hypoxic conditions (<2mgl−1) extended into Charlotte Harbor. A long-term fisheries-independent monitoring program (1989 to present) was already in place in Charlotte Harbor, and sampling was intensified during the month after the storm. Changes in fish assemblages that resulted from the hypoxic event were determined using nonmetric multidimensional scaling and similarity percentages analysis. At the mouth of the Peace River and upper Charlotte Harbor, fish abundance decreased dramatically after the hurricane, and typical estuarine fish assemblages were replaced by those dominated by a few resilient estuarine and freshwater species, including the nonindigenous brown hoplo (Hoplosternum littorale) and sailfin catfish (Pterygoplichthys spp.). Fish assemblages in the estuarine portion of the Maykka River, located only a few kilometers west of the Peace River, were unaffected. The hypoxic event was short lived; dissolved oxygen and estuarine fish assemblages in the Peace River and upper Charlotte Harbor recovered within a month. The results of this study are consistent with other hurricane-related hypoxic events in the literature which have reported acute effects to estuarine systems in the short term, rapid recoveries, and long-term resilience.  相似文献   

4.
During the summer of 2004, four hurricanes (Charley, Frances, Ivan, and Jeanne) affected Florida between August 13 and September 27. Two storms (Frances: category 2 and Jeanne: category 3) made landfall in the southern portion of the Indian River Lagoon (IRL) on the east-central coast of Florida. The presence of Florida Fish and Wildlife Conservation Commission's long-term fisheries monitoring program in the IRL provided a unique opportunity to examine the effects of large tropical events on estuarine fish communities. Increased sampling efforts to monitor the effects of tropical disturbances on the fish community within the IRL and one of its major tributaries (St. Sebastian River) were initiated within days after the passing of the last hurricane (Jeanne). The objectives of the study were to characterize changes to the composition of the fish community within the lagoon and river immediately after the passage of two hurricanes, and to examine the recovery of the fish communities. Analyses indicated that immediately after the last hurricane passed, community diversity within the estuary decreased following these storms due to the absence of many marine species, whereas the fish community within the St. Sebastian River shifted to one containing a greater percentage of freshwater species. Recovery of the community structure to pre-hurricane conditions was evident within several weeks following the last hurricane, and by mid December 2004 (ca. 3 mo after the last storm), there was little difference between the pre-hurricane and post-hurricane fish communities.  相似文献   

5.
The spatial/temporal scaling problem (i.e., fitting a given research question to the dimensions of variability of the study area) is particularly pronounced in highly variable systems such as estuaries. Long-term, multidisciplinary studies in the Apalachicola Bay system were used to evaluate variation of different physical, chemical, and biological factors. Specific limitations of weekly, monthly, and quarterly sampling intervals were directly related to the efficiency of the sampling gear, the range of variation in the study parameters, and specific biological features (motility, recruitment, natural history) of infaunal macroinvertebrates and epibenthic organisms. There are families of spatial and temporal scaling phenomena that should be considered when establishing a given field sampling program. The dimensions of variation change along spatial/temporal gradients of salinity, habitat complexity, and productivity and among different levels of biological organization. The limits of variation define the needed sampling effort for a given level of estimation. Without an adequate evaluation of such variation, representative samples cannot be taken; the resulting inadequate sampling effort often precludes reliable comparisons and robust generalization. There is a continuum of scaling dimensions (and sampling problems) that ranges from small-scale experimental approaches to system-wide analyses. Misapplication of such scaling estimates has led to overgeneralization of experimental results. Currently, there is widespread misapplication of combinations of unrelated, limited sampling efforts to broad-scale resource problems. The loss of valuable estuarine resources is favored by the lack of adequate scientific databases that are consistent with the dimensions of the individual study areas. Unless experimental studies and field sampling programs are scaled to the dimensions of the research problem and the study area in question there will be a continued proliferation of trivial studies at one end of the continuum and the progressive deterioration of estuarine resources at the other.  相似文献   

6.
Almost all engineering evacuation models define the objective as minimizing the time required to clear the region or total travel time, thus making an implicit assumption that who will or should evacuate is known. Conservatively evacuating everyone who may be affected may be the best strategy for a given storm, but there is a growing recognition that in some places that strategy is no longer viable and in any case, may not be the best alternative by itself. Here, we introduce a new bi-level optimization that reframes the decision more broadly. The upper level develops an evacuation plan that describes, as a hurricane approaches, who should stay and who should leave and when, so as to minimize both risk and travel time. The lower level is a dynamic user equilibrium (DUE) traffic assignment model. The model includes four novel features: (1) it refocuses the decision on the objectives of minimizing both risk and travel time; (2) it allows direct comparison of more alternatives, including for the first time, sheltering-in-place; (3) it uses a hurricane-scenario-based analysis that explicitly represents the critically important uncertainty in hurricane track, intensity, and speed; and (4) it includes a new DUE algorithm that is efficient enough for full-scale hurricane evacuation applications. The model can be used both to provide an evacuation plan and to evaluate a plan’s performance in terms of risk and travel time, assuming the plan is implemented and a specified hurricane scenario then actually occurs. We demonstrate the model with a full-scale case study for Eastern North Carolina.  相似文献   

7.
Shallow estuarine habitats often support large populations of small nekton (fishes and decapod crustaceans), but unique characteristics of these habitats make sampling these nekton populations difficult. We discuss development of sampling designs and evaluate some commonly used devices for quantitatively sampling nekton populations. Important considerations of the sampling design include the size and number of samples, their distribution in time and space, and control of tide level. High, stable catch efficiency should be the most important grear characteristic considered when selecting a sampling device to quantify nekton densities. However, the most commonly used gears in studies of estuarine habitats (trawls and seines) have low, variable catch efficiency. Problems with consistently low catch efficiency can be corrected, but large unpredictable variations in this gear characteristic pose a much more difficult challenge. Study results may be bised if the varibility in catch efficiency is related to the treatments or habitat characteristics being measured in the sampling design. Enclosure devices, such as throw traps and drop samplers, have fewer variables influencing catch efficiency than do towed nets (i.e., trawls and seines); and the catch efficiency of these enclosure samplers does not appear to vary substantially with habitat characteristics typical of shallow estuarine areas (e.g., presence of vegetation). The area enclosed by these samplers is often small, but increasing the sample number can generally compensate for this limitation. We recommend using enclosure samplers for estimating densities of small nekton in shallow estuarine habitats because these samplers provide the most reliable quantitative data, and the results of studies using these samplers should be comparable. Many kinds of enclosure samplers are now available, and specific requirements of a project will distate which gear should be selected.  相似文献   

8.
Several interrelated factors affect, water quality in the Albemarle-Pamlico Estuarine System (APES) including land use change in the upland and coastal watersheds, legislatively mandated basin-wide nutrient management plans, intense storms, and global and local changes in sea level. Despite its importance as an essential fish habitat, the APES has not been monitored as intensively or extensively for habitat impacts associated with decreased water quality as other estuaries have been, such as with the North Carolina tributary estuaries or Chesapeake Bay. To support the sustainable use of these estuaries, we are developing an automated water quality monitoring system aboard ferries that traverse the APES. This program, FerryMon, provides a unique, long-term, and cost-effective monitoring system to evaluate status and trends in APES water quality. Intensive temporal and spatial data obtained from all ferry routes provide an environmental baseline and are used to assess the patterns and variability in surface water hydrography, dissolved constituents, and particulate matter. The data are useful to calibrate estimates of ocean color and sea surface temperature from aircraft and satellite sensors. We are creating a searchable geographic database that is intended for scientists, managers, and the general public. Using ferries as sampling platforms to monitor estuarine water quality is a tractable approach and FerryMon represents a model for use in other large bodies of water traversed by ferries.  相似文献   

9.
Estuarine organisms can be considered three ways as bioindicators—first, as indicators of a defined set of environmental conditions, second, as indicators of contaminant loads on the system, and third, as indicators of the overall health of the system. By their very nature, estuarine organisms are eurytolerant and this, along with the various stratagems that have evolved to cope with the problems of life in estuaries results in a confusing picture for the estuarine manager. The recommended bioindicators for estuarine conditions are plankton; for contaminant loads, a range of species with different feeding types; and for system status, a eurytolerant species, such as the musselMytilus edulis for laboratory monitoring or a “target” species such as the clamMacoma balthica for field monitoring. However, it would be unwise to rely on a single indicator, and the recommendation is that the final choice, and preferably choices, be tailored to the desired goal.  相似文献   

10.
Since the mid 1990s, the Atlantic and Gulf Coast regions have experienced a dramatic increase in the number of hurricane landfalls. In eastern North Carolina alone, eight hurricances have affected the coast in the past 9 years. These storms have exhibited individualistic hydrologic, nutrient, and sediment loading effects and represent a formidable challenge to nutrient management aimed at reducing eutrophication in the Pamlico Sound and its estuarine tributaries. Different rainfall amounts among hurricanes lead to variable freshwater and nutrient discharge and variable nutrient, organic matter, and sediment enrichment. These enrichments differentially affected physical and chemical properties (salinity, water residence time, transparency, stratification, dissolved oxygen), phytoplankton primary production, and phytoplankton community composition. Contrasting ecological responses were accompanied, by changes in nutrient and oxygen cycling, habitat, and higher trophic levels, including different direct effects on fish populations. Floodwaters from the two largest hurricances, Fran (1996) and Floyd (1999), exerted, multi-month to multi-annual effects on hydrology, nutrient loads, productivity, and biotic composition. Relatively low rainfall coastal hurricanes like Isabel (2003) and Ophelia (2005) caused strong vertical mixing and storm surges, but relatively minor hydrologic and nutrient effects. Both hydrologic loading and wind forcing are important drivers and must be integrated with nutrient loading in assessing short-term and long-term ecological effects of these storms. These climatic forcings cannot be managed but should be considered in the development of water quality management strategies for these and other large estuarine ecosystems faced with increasing frequencies and intensities of hurricane activity.  相似文献   

11.
Although hurricane disturbance is a natural occurrence in mangrove forests, the effect of widespread human alterations on the resiliency of estuarine habitats is unknown. The resiliency of mangrove forests in southwest Florida to the 2004 hurricane season was evaluated by determining the immediate response of mangroves to a catastrophic hurricane in areas with restricted and unrestricted tidal connections. The landfall of Hurricane Charley, a category 4 storm, left pronounced disturbances to mangrove forests on southwest Florida barrier islands. A significant and negative relationship between canopy loss and distance from the eyewall was observed. While a species-specific response to the hurricane was expected, no significant differences were found among species in the size of severely impacted trees. In the region farthest from the eyewall, increases in canopy density indicated that refoliation and recovery occurred relatively quickly. There were no increases or decreases in canopy density in regions closer to the eyewall where there were complete losses of crown structures. In pre-hurricane surveys, plots located in areas of management concern (i.e., restricted connection) had significantly lower stem diameter at breast height and higher stem densities than plots with unrestricted connection. These differences partially dictated the severity of effect from the hurricane. There were also significantly lower red mangrove (Rhizophora mangle) seedling densities in plots with restricted connections. These observations suggest that delays in forest recovery are possible in severely impacted areas if either the delivery of propagules or the production of seedlings is reduced by habitat fragmentation.  相似文献   

12.
Sea-level rise will increase the area covered by hurricane storm surges in coastal zones. This research assesses how patterns of vulnerability to storm-surge flooding could change in Hampton Roads, Virginia as a result of sea-level rise. Physical exposure to storm-surge flooding is mapped for all categories of hurricane, both for present sea level and for future sea-level rise. The locations of vulnerable sub-populations are determined through an analysis and mapping of socioeconomic characteristics commonly associated with vulnerability to environmental hazards and are compared to the flood-risk exposure zones. Scenarios are also developed that address uncertainties regarding future population growth and distribution. The results show that hurricane storm surge presents a significant hazard to Hampton Roads today, especially to the most vulnerable inhabitants of the region. In addition, future sea-level rise, population growth, and poorly planned development will increase the risk of storm-surge flooding, especially for vulnerable people, thus suggesting that planning should steer development away from low-lying coastal and near-coastal zones.  相似文献   

13.
The most recent spate of hurricanes to strike the United States and Caribbean (1989 to the present) has occurred when many of the affected areas had long-term water quality and biological data collection efforts ongoing, as well as special follow-up studies. These data have allowed researchers to obtain a much clearer picture of how individual characteristics of hurricanes interact with human land use to lead to various types and degrees of environmental effects. Common deleterious water quality effects associated with hurricanes include excessive nutrient loading, algal blooms, elevated biochemical oxygen demand and subsequent hypoxia and anoxia, fish and invertebrate kills, aquatic animal displacements, large scale releases of chemical pollutants and debris from damaged human structures, exacerbated spread of exotic species and pathogens, and pollution of water with fecal microbial pathogens. These and other effects may or may not occur, or occur to varying degrees, depending upon individual hurricane characteristics including category, point of landfall, wind speed, amount of rainfall, and path after landfall. Landfall in a populous area, a post-landfall trajectory upriver toward a headwater region, passage along a floodplain containing pollution sources (such as wastewater treatment plants, concentrated animal feeding operations, and septic systems), and intensity sufficient to damage power generation will all lead to increased environmental damage. We suggest a number of recommendations for post-hurricane water sampling parameters and techniques, and provide several management-oriented recommendations for better coastal and floodplain land use aimed at lessening the water quality effects of hurricanes.  相似文献   

14.
平阴县浅层地下水调查采样密度为1点/16km^2,分析测试27项指标的含量变化规律后,认为调查区浅层地下水中除K,Mn,NO2^-等指标含量变化较大,局部富集外,其他指标含量变化小,在浅层地下水中分布较均匀。选择As,Ba,Be,Cd,Co,Cu,Fe,Hg,Mn,Mo,Ni,Pb,Se,Zn,F^-,Cl^-,Cr^6+,NO2^-,COD,pH等20项指标,按《地下水质量标准》对浅层地下水环境质量进行的单因子和综合评价,结果显示较好级以上者达88.4%,而较差级仅占11.6%,无极差级分布,调查区内浅层地下水环境质量状况良好。  相似文献   

15.
An analytical method has been developed for evaluating the dependence of historical fish stock levels on estuarine pollutant loadings. Categorical time series regressions were used to derive preliminary relationships among previous levels of stock size, climatic variables, and pollution indicators. The analysis technique is used here to evaluate hypotheses on the effects of human population changes and dredging activity on stock histories of the Potomac estuary’s striped bass and American shad, for the period 1929 through 1976. Whereas climatic factors dominate striped bass dynamics compared to the two pollution variates tested, the American shad stock shows strong dependence on human population levels (but not on dredging activity) compared to climatic factors. Analyses of this type will be extended for examining the effects of specific pollutants on other important exploited stocks in five northeastern eatuaries.  相似文献   

16.
Shrimp culture technology has resulted in development of a major shrimp farming industry worldwide. Without the shrimp farming industry, increasing demands for shrimp by consumers could not be met, resulting in increased pressure on wild shrimp resources. Unfortunately, there are realized and potential adverse environmental effects on estuarine ecosystems as a result of shrimp farming. The effects can be categorized as wetland destruction for construction of shrimp farms, hypernutrification of estuarine ecosystems by shrim pond effluent, “biological pollution” of native shrimp stocks through escapement of aquaculture stocks, water use and entrainment of estuarine biota, and impacts of shrimp farm chemicals on estuarine systems. While the shrimp farming industry in the United States is small, the United States is effectively addressing all the realized and potential environmental impacts through regulation and research at the federal and state levels. Areas of regulation and research include stringent prohibitions on wetland destruction, regulation of effluents and support of research to eliminate and/or reduce effluents, escapement prevention technology and development of high-health stocks, minimizing entrainment of estuarine biota through water conservation and screening technology, and regulation of chemical use in the shrimp farming industry and support of research on shrimp pathology and environmentally safe disease control. Work is still in progress and not all problems have been resolved to the complete satisfaction of shrimp farmers and estuarine conservationists. However, the situation in the United States should serve as a model of how to encourage sustainable economic development through commercial shrimp farming while abating adverse environmental impacts on estuarine systems. To further improve the situation, the development and adoption of “best management practices” for shrimp aquaculture are recommended.  相似文献   

17.
Spatial patterns of environmental processes are intrinsic yet complex components of estuaries. Spatial characterization of environmental gradients is a necessary step to better understand and classify estuarine environments. A geographic information system is developed to analyze the major abiotic environmental processes, to evaluate accuracy and spatial uncertainty, and to analyze potential zonation within the choked coastal lagoon of Chincoteague Bay in Maryland and Virginia, USA. Spatially extensive grid-based models of environmental gradients are constructed from existing geospatial and environmental databases, including tidal prism, bathymetry, salinity, wave exposure, and Secchi disk depth. Integration of wetland boundaries and bathymetric data provide for full basin analysis of flushing and tidal prism. Multivariate Principal Components Analysis demonstrates the covariation among gradients and provides an empirical approach to mapping multidimensional zones within the lagoon. The project documents the development of an estuarine geographic information system that can be used to analyze and compare estuarine environments and provide data for environmental decision making.  相似文献   

18.
Following the catastrophic and devastating Atlantic Hurricane seasons in 2004 and 2005, there has been increased interest in formulating planning directives and policy aimed at minimizing the societal impacts of future storms. Not all populations will evacuate an area forecast to be affected by a hurricane, so emergency managers must plan for these people who remain behind. Such planning includes making food, water, ice, and other provisions available at strategic locations throughout an affected area. Recent research has tackled problems related to humanitarian and relief goods distribution with respect to hurricanes. Experience shows that the torrential rains and heavy winds associated with hurricanes can severely damage transportation network infrastructure rendering it unusable. Scanning the literature on hurricane disaster relief provision, there are no studies that expressly consider the potential damage that may be caused to a transportation network by strong storms. This paper examines the impacts of simulated network failures on hurricane disaster relief planning strategies, using a smaller Florida City as an example. A relief distribution protocol is assumed where goods distribution points are set up in pre-determined locations following the passage of a storm. Simulation results reveal that modest disruptions to the transportation network produce marked changes in the number and spatial configuration of relief facilities. At the same time, the transportation network appears to be robust and is able to support relief service provision even at elevated levels of hypothesized disruption.  相似文献   

19.
We focus on the question of whether high phytoplankton production events observed in a United States Pacific Northwest estuary consist of estuarine species blooms fueled by oceanic nutrient input or reflect offshore oceanic blooms that have advected into the estuary. Our approach is to use certain phytoplankton species as indicators associated with water mass origin, either estuarine or oceanic, to help resolve this question in Willapa Bay, Washington. We used species analysis and primary production data from 10 selected dates in May–September of 1998 and 1999, representing periods of high through low productivity. Out of 108 phytoplankton species identified from Willapa Bay, nine were selected and tested as indicators of oceanic species, six as estuarine, and two as surf zone. Our test results demonstrated the oceanic and estuarine species to be satifactory indicators of source waters. The prevalence of these species indicators in our samples revealed that the highest primary production and the appearance ofPseudo-nitzschia spp. were associated with oceanic intrusions of phytoplankton biomass into Willapa Bay. While the largest blooms were oceanic in origin, numerous medium-sized production events were from either oceanic, surf zone, or estuarine sources, indicating a complex situation.  相似文献   

20.
Estimated pollutant loadings to Long Island Sound (LIS) are presented and discussed in the context of current information on population trends and land-use characteristics within the drainage basin of the sound. For the conventional pollutants (BOD, N, and P) and for most of the metals examined, the fluxes to LIS from wastewater treatment plants approach or exceed the fluxes from riverine sources. Urban runoff is a significant source for only a few contaiminants, such as lead and petroleum hydrocarbons. Atmospheric flux estimates made for other are s are extrapolated to LIS, and this source appears to be significant for lead, zinc, polynuclear aromatic hydrocarbons, and chlorinated pesticides. Continued population growth is projected through 2010, both in the urban centers of the western sound and in the coastal counties surrounding the central and eastern portions of LIS. This growth will place increased pollution pressure on the sound and increased demands on already scarce coastal and estuarine land-use categories. Close interaction between environmental planners, managers, and scientists is required to identify effective control strategies for reducing existing pollutant stress to the sound and for minimizing the effects of future development.  相似文献   

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