共查询到20条相似文献，搜索用时 921 毫秒
1.
Despite the widely acknowledged threat posed by invasive species in coastal estuaries, there are substantial gaps at the intersection
of science and policy that are impeding invasive species management. In the face of pressing management needs in coastal and
estuarine environments, we advocate that introduced species should receive the kind of management effort dedicated, for example,
to reducing pollution. We support our argument with some examples of economic costs of estuarine and coastal introduced species
and a summary of recent evidence for the ecological costs. We highlight some of the issues that either thwart or facilitate
the successful marriage between science and management of introduced species, including the regulatory framework for management.
We use the available information on coastal eradication programs, including case histories of the programs for Caulerpa taxifolia and Spartina alterniflora (and hybrids) in the western USA, to indicate the feasibility of managing introduced species and to help point out how management
and science can improve the outcome. We close with a research agenda that focuses primarily on science that will really assist
with invasive species management and reflects our own experience and the opinions of managers directly involved with this
issue. 相似文献
2.
A conceptual model of estuarine freshwater inflow management 总被引：1，自引：0，他引：1
Merryl Alber 《Estuaries and Coasts》2002,25(6):1246-1261
As humans continue to influence the quantity, timing, and quality of freshwater input to estuaries, it is becoming increasingly common for policies to be enacted that mandate the establishment of freshwater inflow criteria that will serve to preserve and protect estuarine ecosystems. This paper reviews the scientific literature describing how changes in freshwater inflow affect estuaries, proposes a conceptual model that explores the roles of scientists, citizens, politicians, and managers in the management of freshwater inflow to estuaries, and uses the model to explore the ways in which freshwater inflow is managed in a variety of estuaries. The scientific review is organized to provide an overview of the connections between freshwater inflow (in terms of the quantity, quality, and timing of water delivery), estuarine conditions (such as salinity and concentrations of dissolved and particulate material), and estuarine resources (such as the distribution and abundance of organisms), and to highlight our understanding of the causative mechanisms that underlie the relationships among these variables. The premise of the conceptual model is that the goal of estuarine freshwater inflow policy is to protect those resources and functions that we as a society value in estuaries, and that management measures use scientific information about the relationships among inflow, conditions, and resources to establish inflow standards that can meet this goal. The management approach can be inflow-based (flow is kept within some prescribed bounds under the assumption that taking too much away is bad for the resources), condition-based (inflow standards are set in order to maintain specified conditions in the estuary), or resource-based (inflow standards are set based on the requirements of specific resources), but each of these is carried out by regulating inflow. This model is used as a framework to describe the development of freshwater inflow criteria for estuaries in Texas, Florida, and California. 相似文献
3.
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
4.
Nitrogen loads to estuaries: Using loading models to assess the effectiveness of management options to restore estuarine water quality 总被引：1，自引：0，他引：1
Nitrogen (N) loading to estuaries has become a major concern for coastal planners. As urban development on coastal watershed
continues, estuaries and bays are becoming more eutrophic, and cascading effects are being felt at every trophic level. Managers
and stakeholders need to have a suite of effective management tools that can be applied to coastal watersheds to minimize
the effects of eutrophication. We applied an N loading model and an estuarine loading model to examine the effectiveness of
a suite of potential management options that could be implemented in Waquoit Bay, Cape Cod, Massachusetts. This estuarine
system is a case study in which we can explore the relative potential effectiveness of decreasing inputs from wastewater and
fertilizer-derived N, diverting nitrogenous runoff from impervious surfaces, altering zoning ordinances, preserving forested
tracts of land as well as freshwater and saltwater wetlands, harvesting macroalgae, dredging estuary channels, and exterminating
waterfowl. From a combination of simulation results, assessment of the magnitude of loads from different sources, and through
different land covers, and the additional consideration of feasibility we identified management options with high, intermediate,
and low potential effectiveness. Improvement of septic system performance, use of zoning regulations, preservation of forested
tracts and freshwater bodies, and conservation of salt marshes emerged as the most promising avenues to manage N loads in
our system. Installation of wastewater treatment plants, controlling fertilizer use, and harvesting macroalgae would potentially
have intermediate success. Diversion of runoff from impervious surfaces, dredging, and extermination of waterfowl show little
promise at reducing N loads. These conclusions potentially set priorities for decision-makers charged with the management
of Waquoit Bay. The same procedures applied to another watershed-estuary system with different land covers and different estuarine
features may differ. Evaluation studies like this need to be done for any particular site, since the watershed-estuary coupling
and the loads delivered to the receiving estuary could differ. The Waquoit Bay case study provides an example of a protocol
that leads to identification of the most promising management options. 相似文献
5.
6.
Material transfer between estuaries and the nearshore zone has long been of interest, but information on the processes affecting Pacific Northwest estuaries has lagged behind other areas. The west coast of the U.S. is a region of seasonally variable upwelling that results in enhanced phytoplankton production in the nearshore zone. We examined estuarine-nearshore links over time by measuring physical oceanographic variables and chlorophylla concentration from an anchor station in South Slough, Oregon. Data was collected during 24-h cruises conducted at approximately weekly intervals during summer 1996 and spring 1997. The results demonstrate that the physical oceanography of this estuarine site was strongly influenced by the coastal ocean. Marine water reached the estuarine site on every sampled tide, and chlorophylla was clearly advected into the estuary with this ocean water. In contrast, phytoplankton concentrations were comparatively reduced in the estuarine water. There were, however, large fluctuations in the import of chlorophyll over the course of the summer. These variations likely reflect upwelling-generated phytoplankton production in the coastal ocean and subsequent cross-shelf transport to the estuary. Suspension feeding organisms in South Slough likely depend on the advection of this coastally-derived phytoplankton. The large allochthonous chlorophyll input measured for this system appears dissimilar from most estuaries studied to date. Previous investigations have focused on the outwelling and inwelling of materials in estuaries. We must now consider the influence of coastal upwelling and downwelling processes on estuarine material exchange. 相似文献
7.
Spatial patterns of estuarine biota suggest that some nearshore ecosystems are functionally linked to interacting processes of the ocean, watershed, and coastal geomorphology. The classification of estuaries can therefore provide important information for distribution studies of nearshore biodiversity. However, many existing classifications are too coarse-scaled to resolve subtle environmental differences that may significantly alter biological structure. We developed an objective three-tier spatially nested classification, then conducted a case study in the Alexander Archipelago of Southeast Alaska, USA, and tested the statistical association of observed biota to changes in estuarine classes. At level 1, the coarsest scale (100–1000’s km2), we used patterns of sea surface temperature and salinity to identify marine domains. At level 2, within each marine domain, fjordal land masses were subdivided into coastal watersheds (10–100’s km2), and 17 estuary classes were identified based on similar marine exposure, river discharge, glacier volume, and snow accumulation. At level 3, the finest scale (1–10’s km2), homogeneous nearshore (depths <10 m) segments were characterized by one of 35 benthic habitat types of the ShoreZone mapping system. The aerial ShoreZone surveys and imagery also provided spatially comprehensive inventories of 19 benthic taxa. These were combined with six anadromous species for a relative measure of estuarine biodiversity. Results suggest that (1) estuaries with similar environmental attributes have similar biological communities, and (2) relative biodiversity increases predictably with increasing habitat complexity, marine exposure, and decreasing freshwater. These results have important implications for the management of ecologically sensitive estuaries. 相似文献
8.
An extensive literature base worldwide demonstrates how spatial differences in estuarine fish assemblages are related to those in the environment at (bio)regional, estuary-wide or local (within-estuary) scales. Few studies, however, have examined all three scales, and those including more than one have often focused at the level of individual environmental variables rather than scales as a whole. This study has identified those spatial scales of environmental differences, across regional, estuary-wide and local levels, that are most important in structuring ichthyofaunal composition throughout south-western Australian estuaries. It is the first to adopt this approach for temperate microtidal waters. To achieve this, we have employed a novel approach to the BIOENV routine in PRIMER v6 and a modified global BEST test in an alpha version of PRIMER v7. A combination of all three scales best matched the pattern of ichthyofaunal differences across the study area (ρ?=?0.59; P?=?0.001), with estuary-wide and regional scales accounting for about twice the variability of local scales. A shade plot analysis showed these broader-scale ichthyofaunal differences were driven by a greater diversity of marine and estuarine species in the permanently-open west coast estuaries and higher numbers of several small estuarine species in the periodically-open south coast estuaries. When interaction effects were explored, strong but contrasting influences of local environmental scales were revealed within each region and estuary type. A quantitative decision tree for predicting the fish fauna at any nearshore estuarine site in south-western Australia has also been produced. The estuarine management implications of the above findings are highlighted. 相似文献
9.
Estuarine Biotope Mosaics and Habitat Management Goals: An Application in Tampa Bay,FL, USA 总被引：1，自引：0，他引：1
Many types of anthropogenic stress to estuaries lead to destruction and conversion of habitats, thus altering habitat landscapes
and changing the “arena” in which the life history interactions of native fauna take place. This can lead to decreased populations
of valued fauna and other negative consequences. The Tampa Bay Estuary Program (TBEP) pioneered a system-wide management framework
that develops estuarine habitat restoration and protection goals based on supporting estuarine-dependent species and the habitat
landscapes they require (for example, the extent of seagrass beds, mangrove forests, oyster reefs, or oligohaline marshes)
within an estuary. We describe this framework and provide related statistics as methods to help managers set system-wide ecological
goals using larger conceptual approaches that are easily communicated to stakeholders and the public; we also discuss applications
of the approach to existing and evolving paradigms of estuarine management. The TBEP and partners used this framework to combine
a simple and unifying vision with a diverse and complex set of management tools, resulting in greatly improved environmental
conditions within Tampa Bay. 相似文献
10.
Living resources in estuarine systems have been so intensively harvested that many fisheries are severely depleted at a time when demand for these resources is rising. In addition, multiple use demands on estuaries often conflict, leaving unresolved management questions. With the movement of the population to the coastal regions, conflicts among uses and users of estuarine resources are increasing. Aquaculture offers one means to reconcile the conflicting demands for use of the estuarine resource. Yet, the nation has few, if any new policy or management approaches to address these conflicts. Management on the level of the watershed is one effective tool that should be more effectively used. Involvement of the full range of stakeholders or user groups in policy setting and management options has brought remarkable success in a small number of cases where this approach has been used. The nation will need to develop other tools and approaches if estuaries are to be restored and protected as protected as planned in federal, regional, and state laws and initiatives. 相似文献
11.
Eutrophication and the development of persistent opportunistic macroalgal blooms are recognised as one of the main detrimental effects of increased anthropogenic pressures on estuarine and coastal systems. This study aimed to highlight the interplay between pressures and controlling physical factors on ecosystem functioning. The hypothesis that hydrological regime can control the growth of opportunistic macroalgae was tested with the study of two Irish estuaries, the Argideen and the Blackwater, with similar nutrient loading sources but divergent hydrological regimes. Seasonal monitoring data was initially examination, while the application of a pre-existing box model allowed a further analysis of the influence of residence time and nutrient load modifications on macroalgal growth. Seasonal oscillations in monitored river flow rates altered nutrient transfer from the catchments to the estuaries in both cases, as is shown through differences between winter and summer nutrient concentrations. In the Argideen, however, the relative contribution of phosphorus (P) from adjacent marine waters was high due to the shorter residence times and greater influx of marine water into the estuary. Modelling studies showed that in the Argideen Estuary, P load reduction would have potentially minimal impact on macroalgal growth due to the shorter residence time which increased the influx of P from marine sources. Nitrogen (N) load reduction of 60 % had a significant, albeit limited, impact on macroalgae and was insufficient in achieving the environmental objectives for this waterbody. For the more river-dominated Blackwater Estuary, modelled reductions in P resulted in a considerable decrease in biomass. Any further P decreases would accentuate the existing disparity in estuarine N:P ratios with possible repercussions for N transport to the coastal system. Hence, the hydrological complexity of estuarine systems demonstrated dictates that a portfolio of separate, but complimentary, management approaches may be required to address eutrophication in these estuaries. 相似文献
12.
Charles T. Roman Norbert Jaworski Frederick T. Short Stuart Findlay R. Scott Warren 《Estuaries and Coasts》2000,23(6):743-764
Geographic signatures are physical, chemical, biotic, and human-induced characteristics or processes that help define similar or unique features of estuaries along latitudinal or geographic gradients. Geomorphologically, estuaries of the northeastern U.S., from the Hudson River estuary and northward along the Gulf of Maine shoreline, are highly diverse because of a complex bedrock geology and glacial history. Back-barrier estuaries and lagoons occur within the northeast region, but the domiant type is the drowned-river valley, often with rocky shores. Tidal range and mean depth of northeast estuaries are generally greater when compared to estuaries of the more southern U.S. Atlantic coast and Gulf of Mexico. Because of small estuarine drainage basins, low riverine flows, a bedrock substrate, and dense forest cover, sediment loads in northeast estuaries are generally quite low and water clarity is high. Tidal marshes, seagrass meadows, intertidal mudflats, and rocky shores represent major habitat types that fringe northeast estuaries, supporting commercially-important fauna, forage nekton and benthos, and coastal bird communities, while also serving as links between deeper estuarine waters and habitats through detritus-based pathways. Regarding land use and water quality trends, portions of the northeast have a history of over a century of intense urbanization as reflected in increased total nitrogen and total phosphorus loadings to estuaries, with wastewater treatment facilities and atmospheric deposition being major sources. Agricultural inputs are relatively minor throughout the northeast, with relative importance increasing for coastal plain estuaries. Identifying geographic signatures provides an objective means for comparing the structure, function, and processes of estuaries along latitudinal gradients. 相似文献
13.
Daniel D. Huppert Rebecca L. Johnson Jessica Leahy Kathleen Bell 《Estuaries and Coasts》2003,26(4):994-1009
This paper explores social, and economic aspects of coastal communities crucial to the management of estuaries in the Pacific Northwest. These aspects include the changing demographics and economies of coastal communities, and the public perceptions, attitudes, and values pertaining to estuarine ecosystems. Information from Willapa Bay and Grays Harbor in Washington and Tillamook, Yaquina, and Coos Bays in Oregon shows that the coastal communities are growing more slowly than the states overall., that the populations are relatively old, and that, although the local economies continue to rely on them, the extractive natural resource industries (fishing, aquaculture, agriculture, forest products) are declining in importance relative to tourism, recreation, and retirement industries. These trends suggest that human uses of the estuaries are changing in character, and altering the management problems. Coastal residents choose to live in these communities to enjoy the views and scenery, to experience rural living, to be near the ocean, and to recreate outdoors. People express coherent perceptions of risks to the estuaries, especially the threats of declining fish habitats, oil spills, shoreline development, invasive species, and logging in upland areas> Residential land values are enhanced by the presence of wetlands and forests and are diminished by the presence of hazardous waste sites. We conclude that, if recent trends in population age structure, income sources, and employment status continue, public attitudes and values will move towards stronger environmental protection. Because ecosystem management involves local public participation and collaboration, estuarine managers will be faced with both increased demands and opportunities. 相似文献
14.
Planktonic larvae of estuarine species often develop in the coastal ocean and return to estuaries using favorable currents.
This study investigated spatial distributions of brachyuran crab post-larvae during ingress to the Newport River estuary,
North Carolina, USA (34°41′ N, 76°40′ W). Nearshore plankton tows were conducted across the inlet to the estuary. Settlement
on passive ‘hog’s hair’ collectors was simultaneously monitored in each of four estuarine channels. Callinectes sapidus density was highest east of the inlet, whereas relative estuarine abundance was higher in western channels. In separate sampling
with collectors at coastal and estuarine locations, spatial distributions of post-larvae were consistent through time but
differed for C. sapidus, Uca spp., and Pachygrapsus transversus. The diel timing of C. sapidus settlement on collectors was determined at the coast and compared to previous studies of settlement in the estuary. Behavioral
responses to environmental cues may alter transport pathways from those predicted by hydrodynamic models. 相似文献
15.
Rafael Santana Guilherme C. Lessa John Haskins Kerstin Wasson 《Estuaries and Coasts》2018,41(1):99-113
Estuarine ecosystem diversity and function can be degraded by low oxygen concentrations. Understanding the spatial and temporal patterns of dissolved oxygen (DO) variation and the factors that predict decreases in DO is thus essential to inform estuarine management. We investigated DO variability and its drivers in Elkhorn Slough, a shallow, well-mixed estuary affected by high nutrient loading and with serious eutrophication problems. Long-term (2001–2012), high-resolution (15 min) time series of DO, water level, winds, and solar radiation from two fully tidal sites in the estuary showed that hypoxia events close to the bottom are common in the summer at the more upstream estuarine station. These events can occur in any lunar phase (spring to neap), at any time of the day, and both on sunny or cloudy days. They are, however, short-lived (lasting in average 40 min) and mainly driven by momentary low turbulent diffusion around slack tides (both at high and low water). Tidal advective transport explains up to 52.1% of the daily DO variability, and the water volume (or DO reservoir) contained in the estuary was not sufficient to avoid hypoxia in the estuary. Solar radiation was responsible for a positively correlated DO daily cycle but caused a decreased in the averaged DO in the summer at the inner station. Wind-driven upwelling reduced the average DO at the more oceanic station during spring. The approach we employed, using robust techniques to remove suspect data due to sensor drift combined with an array of statistical techniques, including spectral, harmonic, and coherence spectrum analysis, can serve as a model for analyses of long-term water quality datasets in other systems. Investigations such as ours can inform coastal management by identifying key drivers of hypoxia in estuaries. 相似文献
16.
A multimetric fish index, the Estuarine Fish Community Index (EFCI) of Harrison and Whitfield (2004), was applied to data
collected for 190 South African estuaries. Estuaries spanned three biogeographic regions and included three distinct estuarine
typologies. The EFCI is based on 14 metrics or measures that represent four broad fish community attributes: species diversity
and composition, species abundance, nursery function, and trophic integrity. Metric reference conditions and scoring criteria
were developed separately for each estuary type within each zoogeographic region. The final EFCI was applied to each estuary
by comparing its fish community with the appropriate reference. Index values ranged between 18 (very poor) and 66 (very good).
A comparison of the EFCI with independent measures of estuarine condition revealed that the index was able to effectively
differentiate between poor and good quality sites. Applying the EFCI to estuaries in which multiple samples were taken also
showed that the index is reproducible. The EFCI is both a robust and sensitive method for assessing the ecological condition
of estuarine systems; it is also an effective communication tool for converting ecological information into an easily understood
format for managers, policy makers, and the general public. 相似文献
17.
Timothy Andrew Stojanovic Hugh D. Ormerod Smith Christopher F. Wooldridge 《GeoJournal》2006,65(3):165-176
Thirteen years since the EU Habitats Directive (1992/43/EEC) became a binding legal agreement, this paper considers the implementation
of this important European environmental legislation as it applies to the coastal activities of seaports and harbours. The
paper examines the relationship between environmental legislation and ports policy, and seeks to provide a comprehensive assessment
of the policy and science that has been developed in relation to protected areas and port management. The paper reports the
results of a survey of European port professionals, and their perception of the successes and challenges of the management
regimes that have been established, as well as their opinions on how these have influenced the management within ports. The
paper also provides a detailed examination of the scientific and technical developments with particular regard to dredging
and habitat management in European ports. Key research gaps are identified, including: practical approaches to licensing procedures;
lack of baseline information, especially with regard to in-combination effects; the efficacy of techniques for mitigating
the impacts of dredging; and greater understanding on how more resilient models for collaborative action can be developed.
The paper will be of use to environmental planners, scientists, regulators, conservationists, and port managers, as they consider
how to apply science and management to the sustainable development and environmental protection of coastal areas. 相似文献
18.
J. B. Adams G. C. Bate T. D. Harrison P. Huizinga S. Taljaard L. van Niekerk E. E. Plumstead A. K. Whitfield T. H. Wooldridge 《Estuaries and Coasts》2002,25(6):1382-1393
The National Water Act (Act 36 of 1998) in South Africa recognizes basic human water requirements as well as the need to sustain the country's freshwater and estuarine ecosystems in a healthy condition for present as well as future generations. In this Act, provision is made for a water reserve to be estimated prior to the authorization of water use (e.g., for agriculture, large volume residential and industrial uses) through licensing. This reserve is the water required to satisfy basic human needs (i.e., 25 1 person?1 d?1) and to protect aquatic ecosystems to ensure present and future sustainable use of the resource. This led the Departments of Water Affairs and Forestry and estuarine scientists throughout South Africa to develop a method to determine the freshwater inflow requirements of estuaries. The method includes documenting the geographical boundaries of the estuary and determining estuarine health by comparing the present state of the estuary with a predicted reference condition with the use of an Estuarine Health Index. The importance of the estuary as an ecosystem is taken from a national rating system and together with the present health is used to set an Ecological Reserve Category for the estuary. This category represents the level of protections afforded to an estuary. Freshwater is then reserved to maintain the estuary in that Ecological Reserve Category. The Reserve, the quantity and quality of freshwater required for the estuary, is determined using an approach where realistic future river runoff scenarios are assessed, together with data for present state and reference conditions, to evaluate the extent to which abiotic and biotic conditions within an estuary are likely to vary with changes in river inflow. Results from these evaluations are used to select an acceptable river flow scenario that represents the highest reduction in freshwater inflow that will still protect the aquatic ecosystem of the estuary and keep it in the desired Ecological Reserve Category. The application of the Reserve methodology to the Mtata estuary is described. 相似文献
19.
Thomas R. Allen Harri T. Tolvanen George F. Oertel George M. McLeod 《Estuaries and Coasts》2007,30(6):959-977
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
20.
In response to legislative directives beginning in 1975, the Texas Water Development Board (TWDB) and the Texas Parks and Wildlife Department (TPWD) jointly established and currently maintain a data collection and analytical study program focused on determining the effects of and needs for freshwater inflows into the state's 10 bay and estuary systems. Study elements include hydrographic surveys, hydrodynamic modeling of circulation and salinity patterns, sediment analyses, nutrient analyses, fisheries analyses, freshwater inflow optimization modeling, and verification of needs. For determining the needs, statistical regression models are developed among freshwater inflows, salinities, and coastal fisheries. Results from the models and analyses are placed into the Texas Estuarine Mathematical Programming (TxEMP) model, along with information on salinity viability limits, nutrient budgets, fishery biomass ratios, and inflow bounds. The numerical relationships are solved within the constraints and limits, and optimized to meet state management objectives for maintenance of biological productivity and overall ecological health. Solution curves from the TxEMP model are verified by TWDB’s hydrodynamic simulation of estuarine circulation and salinity structure, which is evaluated against TPWD’s analysis of species abundance and distribution patterns in each bay and estuary system. An adequate system-wide match initially verifies the inflow solution. Long-term monitoring is recommended in order to verify that implementation of future water management strategies maintain ecological health of the estuaries and to provide an early warning of needs for adaptive management strategies. 相似文献