Introduction to Special Issue on Tropical Coastal Management

In 1992, scientists at National Estuarine Research Reserve (NERR) sites proposed establishing a national coordinated monitoring program that would attempt to identify and track short-term variability and long-term changes in representative estuarine ecosystems and coastal watersheds. Known as the NERR System-Wide Monitoring Program (SWMP), it currently consists of monitoring water quality and atmospheric variables over a range of spatial and temporal scales. Additional monitoring of ecological resources and land-water use will follow in subsequent components of the program. Water quality monitoring at NERR sites includes measurements of pH, conductivity, temperature, dissolved oxygen, turbidity, and water level. The NERR sites use data loggers that record at 30-minute intervals and relay measurements to internal memory. Standardized protocols assure that sampling, processing, and data management techniques are comparable among sites. Statistical techniques are being used to identify periodicity in water quality variables. Periodic regression analysis indicated that diel periodicity in dissolved oxygen is a larger source of variation than tidal periodicity at sites with less tidal amplitude. Tidal periodicity, however, is more important at sites with a tidal amplitude greater than 1 m. This finding suggests that natural processes controlling dissolved oxygen levels differ among sites depending upon tidal amplitude. Water quality data from the NERR SWMP have also been used to investigate occurrence of hypoxia. Results from analysis of water quality at several reserves indicate that hypoxia occurs but that the percentage of time that dissolved oxygen was less than 28% saturation varied substantially among sites and between years. Most of the hypoxic events occurred in summer but were also observed in winter and fall when low dissolved oxygen is usually not considered a problem. Without continuous monitoring by the NERR SWMP, many low dissolved oxygen events would have been missed, thus underestimating the duration and potential impact of this type of water quality variability. The NERR SWMP provides a unique opportunity to increase our understanding of how various environmental factors influence estuarine processes. Only by understanding how estuaries function and change naturally over time will we be able to predict how these systems respond to changes in climate and human-induced perturbations.     

Upstream pollution sources and coastal water quality protection in North Carolina

Abstract

A watershed‐based approach to water quality management is necessary for protecting coastal water quality, but the relative importance of inland pollution sources on estuaries is often overestimated. This can lead to a misallocation of coastal water protection resources and ignorance of coastal zone pollution sources. This overestimation of upstream contributions is attributable to a failure to recognize that many estuaries have little or no inland drainage area, the confusion of basinwide pollutant loading with pollutant delivery to estuaries, the low delivery ratios for many pollutants within drainage basins, and disproportionately high pollutant delivery for sources within the coastal zone. Examples are given from North Carolina. As a general rule, resources expended on pollution control within or near the coastal zone will result in more coastal water quality improvement per unit effort than resources expended upstream.     

A three-dimensional, wave-current coupled, sediment transport model for POM

In the high-energy environment of coastal seas and estuaries,strong sediment resuspension/ deposition events are driven by surface waves,tides,winds and buoyancy driven currents.In recent years,A POM based three-dimensional,wave-current coupled,sediment transport model has been developed by the University of New South Wales.This paper presents several examples of the model applications to study sediment dynamics in the environments where forcings such as waves,tides,and winds are equally important to affect sediment fluxes and distributions.Firstly,the sediment transport model coupled to the Yellow Sea general circulation model and a third generation wave model SWAN was implemented in the Yellow Sea to study the dynamics of the sediment transport and resuspension in the northern Jiangsu shoal-wate(rNJSW).The sediment distributions and fluxes and their inter-annual variability were studied by realistic numerical simulations.The study found that the surface waves played a dominant role over the tides to form the turbidity maxima along the muddy coast of NJSW. Secondly,the sediment transport model was used to explore the effect of suspended sediment-induced stratification in the bottom boundary laye(rBBL).The model uses a re-parameterized bottom drag coefficient Cd that incorporates a linear stability function of flux Richardson number Rf.The study has shown that the sediment induced stratification in the BBL reduces the vertical eddy viscosity and bottom shear stress in comparison with the model prediction in a neutrally stratified BBL.In response to these apparent reductions,the tidal current shear is increased and sediments are abnormally concentrated within a thin wall layer that is overlain by a thicker layer with much smaller concentration.The formation of this fluid-mud layer near the seabed has led to a significant reduction in the total sediment transport.This study contributes to the understanding of formations of tidal flats along the coasts of turbid seas and estuaries.     

Protecting Estuaries and Coastal Wetlands through State Coastal Zone Management Programs

This article, one part of the National Coastal Zone Management Effectiveness Study, evaluates the effectiveness of state coastal management programs in protecting estuaries and coastal wetlands. State programs were evaluated in a four-step, indicatorbased process to estimate (1) the relative importance of the issue; (2) the potential effectiveness of programs based on the policies, processes, and tools used; (3) outcome effectiveness based on on-the-ground indicators; and (4) overall performance, where outcome effectiveness was compared to issue importance and potential effectiveness. State evaluations were synthesized to provide a national perspective on CZM contributions and effectiveness in estuary and wetland protection. Although on-the-ground outcome data were sparse, they were sufficient to determine at least probable levels of effectiveness for about one-third of the states. Of these states, 80% were performing at expected or higher levels, considering how important the issue was in their state, and the scope and strength of the policies, processes, and tools they had deployed. Monitoring and record keeping, freshwater wetland management, and the use of nonregulatory restoration in coastal management were common program weaknesses. The evaluation approach and indicators used here are recommended as a starting point for designing a national monitoring and performance evaluation system addressing this CZM objective.     

Marine log transportation and handling systems in british columbia: Impacts on coastal management

Abstract

Over 90 percent of British Columbia's annual log harvest enters into complex water‐based systems of transportation, storage, and handling. These systems have considerable impacts on a wide range of coastal resources and uses. A number of site‐specific conflicts have arisen between forestry and preexisting or emerging values including fisheries, mariculture, recreational boating, and harbor redevelopment. Specific data on the impacts leading to conflict are often fragmentary. However, concerns about highly valued and fragile areas‐particularly estuariesalong with industrial concerns regarding log losses and handling efficiency, have prompted changes in log handling. These include moves to dryland sorting, log bundling, and a redistribution of forestry activities in estuaries to accommodate other values. Conflict adjustments and responses have in the past been largely ad hoc and attempted in a jurisdictional vacuum concerning control of coastal management. A more inclusive strategy is now slowly emerging, which involves the coordinated participation of federal, provincial, and industrial interests.     

A combined science and management framework for developing regional monitoring objectives

Abstract

Designing environmental monitoring programs to deal with widespread, subtle, and/or cumulative impacts on a regional basis is challenging. It requires a shift away from focusing primarily on individual point sources to a more regional perspective. It also necessitates involving scientists and managers together in a cooperative effort to establish priorities and articulate clear objectives. In our view, this objective‐setting task is neither a strictly scientific nor a strictly management activity. It depends on effective communication between scientists and managers but is confounded by differing perspectives, value systems, and behaviors. We present a conceptual framework to assist managers and scientists in this process. This is intended to structure such communication by helping to create a context that permits fruitful give‐and‐take between the two groups. We then describe a six‐part model for specifying the key elements of regional monitoring objectives.     

Numerical simulations of seasonal and interannual variability of the Black Sea thermohaline circulation

The Black Sea general circulation is simulated by a primitive equation model with active free surface. The forcing is seasonally variable and is based on available climatic data. The model reproduces the main features of the Black Sea circulation, including the river discharge effects on the mean sea level and the Bosphorus outflow. Model results show that the simulated sea surface elevation increases in spring over the whole sea, reaching a maximum in the Danube delta area. In the same region, a minimum is observed in winter. The amplitude of the seasonal oscillations (about 8–12 cm over the whole basin) is of the same order of magnitude as the maximum horizontal variations (about 15–18 cm between the coastal areas and the basin interior). This strong signal formed mostly by river discharges, along with the seasonal variability in the other forcing functions and the local dynamics creates a well-pronounced interannual variability. The performance of the model in simulating the seasonal and interannual variability is critically analyzed, with a special attention on the cold intermediate water formation and the circulation in the upper 150 m. The simulations demonstrate that the source of intermediate waters is on the shelf, and that the water mass in the core of cold intermediate layer changes with time as a response to the periodic forcing at sea surface. This type of variability is characterized by pronounced interannual changes, proving that important differences could exist between water mass structure in different years, even when using identical atmospheric forcings each year.     

Scientific requirements for an abyssal benthic laboratory

For over thirty years man has studied “outer space” and installed satellites which watch the surface of the Earth. The great depths of the world ocean are, however, practically unknown and there is an urgent need to put abyssal benthic laboratories into “inner space” in order to study basic phenomena of interest to marine science and climatology as well as man's impact on the oceans.In view of the numerous problems related to global change, as a first step emphasis should first be on the role of the oceans and their inherent processes, which are the focus of such international programmes as the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS). Multi-disciplinary registration of key events at selected key sites investigating the variability in time and space are of the utmost importance. The same methods and techniques must be used for the study of human impacts on the deep oceans caused by mining of metalliferous resources and by waste disposal as well as in basic studies. However, the investigation of the inner space of our planet has certain requirements. As long-term and large-scale investigations become more and more important, development of automized systems, largely independent from research vessels will be required. This will demand high capacities of energy for all technical functions as well as high storage capacities for data and samples. As a consequence the needs for two different—although overlapping—functional approaches are defined for future deep-sea deployments.(A) A system for long-term registration of the natural variability and long-term monitoring of human impacts: (B) A system for short-term observations and short-time experimentations. This report summarizes their technological demands. The envisioned interdisciplinary technology should deliver information on physical, biological and geochemical processes and their variabilities in the deep oceans. The prospected systems need to have the ability for real time video observation, data transfer and experimental manipulation, as well as sensing and sampling facilities with large storage capacities for long-term deployments.Prospective costs of the described multipurpose abyssal benthic laboratory will presumably exceed the funds for deep-sea research of a single country. A joint European effort could solve this problem and help to manifest a leading role for European marine science in international deep-sea and global change research.     

两种水质现状评价方法在港口环境影响评价中的应用

根据对水质的监测结果和取水口附近底栖动物的调查结果,分析南通港两个通用散货泊位工程建设对下游狼山水厂取水口水质的影响。用综合生物指数法对取水口附近水域水质评价的结果显示:狼山水厂取水口的综合水质评价等级为轻污,与水质理化指标的评价结果相吻合。综合生物指数评价法与水质理化指标评价法的结果相互印证,这两种水质现状评价方法可在港口环境影响评价中应用,并互为补充。     

Nutrient Assimilation Services for Water Quality Credit Trading Programs: A Comparative Analysis with Nonpoint Source Credits

Water quality trading programs allow regulated point sources to meet some nutrient control requirements by buying nutrient reduction credits from other pollutant sources. Reduction credits can be created when agricultural land managers implement best management practices and regulators predict that those practices will result in water quality conditions equivalent to controlling discharges at the regulated source. However, natural variability in runoff combines with model and data limitations to make predictions of water quality equivalence uncertain. Nutrient assimilation credits can be created by increasing the capacity of the ecosystem to assimilate nutrients through investments in aquatic plant biomass creation and harvest, shellfish aquaculture, stream restoration, and wetlands restoration and creation. Nutrient assimilation credits and agricultural nonpoint source reduction credits are evaluated based on a number of water quality criteria including service quantification certainty, temporal matching, additionality, and leakage. Nutrient assimilation credits can provide greater certainty than agricultural best management practices in producing equivalent water quality outcomes and should be an option in trading programs.     

Comparison of trends in tributyltin concentrations among three monitoring programs in the United States

The results of three national monitoring programs in the United States (U.S.) that measure concentrations of tributyltin (TBT) are compared. Regional and site comparisons are made of changes in TBT concentrations since passage of the Organotin Antifouling Paint Control Act (OAPCA) in 1988. The monitoring programs compared are the U.S. LongTerm Monitoring Program conducted by a consortium of tributyltin manufacturers, the National Oceanic and Atmospheric Administration's National Status and Trends Mussel Watch project, and the U.S. Navy's TBT monitoring program. All of the monitoring results demonstrate declining TBT concentrations over time. These declines have occurred rapidly (within a few years) and are considerable (56%–71% decrease in TBT concentrations in water, 47%–55% decrease in sediments, and 40%–82% decrease in bivalve tissues). Mean TBT concentrations in water are generally below the current U.S. Environmental Protection Agency marine chronic water quality criterion of 10ng/L. These results indicate that the OAPCA has been effective in reducing TBT concentrations in the aquatic environment.     

Regional Ocean Governance in China: An Appraisal of the Clean Bohai Sea Program

In 2001 China embarked on an ambitious program to improve water quality through creation of the Clean Bohai Sea Program (CBSP). It is the first regional ocean governance program in China. The joint conference of central and local government units directed CBSP under the leadership of the State Environment Protection Administration. To meet the environmental objectives established by the joint conference local governments must pay for the program and operate it, but to date they have not been able to fully fund the effort. Although data indicate a decline of polluted discharges to the Bohai, one tabulation shows that the area of the sea that is polluted has increased each year from 2001 to 2005. Future enhancement of CBSP depends on revising incentives to better link local environmental programs and development, establishing funding mechanisms to equitably spread costs throughout watersheds, and creating comprehensive monitoring programs to better appraise program results.     

On the observability of the fortnightly cycle of the Tagus estuary turbid plume using MODIS ocean colour images

Using three years (2003 to 2005) of MODIS-Aqua normalized water-leaving radiance at 551 nm this paper shows a fortnightly cycle in the Tagus estuary turbid plume. The Tagus estuary is one of the largest estuaries of the west coast of Europe and is located in the most populated area of Portugal, including the capital Lisbon. The turbid plume has been detected by the backscattering characteristics of the surface waters in the vicinity of the estuary mouth. In fortnightly scales, the turbid plume has smaller dimensions during and after neap tides and higher dimensions during and after spring tides. This is most probably associated with the fortnightly spring–neap tidal cycle and the consequent increase in turbidity inside the estuary during spring tides. During the summer weak spring tides (tidal amplitude approximately 2.5 m) no turbid plume is observed for an entire fortnightly cycle. Outside the summer months, precipitation, river discharge and winds, were found to increase the turbid area, but the fortnightly cycle appears to be superimposed on the large time-scale variability, and present throughout the year.     

港口施工的生态影响及对策措施

港口施工可能会导致陆地、潮间带及近岸海域生态环境发生变化。文章对潜在的渔业资源和底栖生物损失的定量计算,对于评估港口施工的生态影响具有重要意义。并提出应采取妥善安排施工时间、合理选址施工场地、加强施工现场管理、注重绿化保护与建设、落实好水土保持工作、积极实施生态补偿与修复、持续开展跟踪监测等措施,可使施工期生态影响大大缓解。     

大规模采沙对弯道滩险的影响

以岷江朱石滩为例,分析大规模采沙对弯道滩险河床演变和航道条件的影响。采沙前,朱石滩河段河床基本冲淤平衡;采沙后,河床冲淤平衡被破坏,河床严重下切,汛期河床回淤剧烈。大规模采沙对弯道滩险航道条件的影响主要表现为破坏航道边界、降低河段水位、增加上游水面比降;原来稳定的弯槽由于水深不足而被舍弃,航道改走不稳定的直槽,给航道维护带来困难;河床地形凌乱,航槽局部存在较大横流,给船舶航行带来安全隐患。     

Estuary Management and Recreational Fishing Benefits

Recognition of the benefits to society supported by estuary ecosystem functions and services, and threats to these benefits posed by human activities, has led to various public programs to restore and protect estuaries at the federal, state, and local levels. As available budgets shrink, program administrators and public elected officials struggle to allocate limited restoration and protection funds to the highest priority areas. Economic benefit and cost information can provide useful inputs into this decision-making process by quantifying estuary restoration and protection benefits and costs in commensurate terms. In this paper, a combined actual and intended travel behavior model is described that can be applied to estimate the recreational fishing benefits of estuary restoration and protection. The model was estimated for recreational fishing in the Lower Atchafalaya River Basin estuary along the Gulf of Mexico, Louisiana, USA coast. Changes in freshwater flows into this estuary may affect redfish and speckled trout game fish populations. The model indicates that changes in catch rates of these two species would have a relatively minor affect on annual fishing trips per angler. However, because total effects may be large when effects per angler are aggregated across total anglers, resource management agencies should consider these changes in recreation benefits when evaluating projects that influence the ecology of coastal estuaries, fish populations, and catch rates. Moreover, in other coastal areas or situations, the responsiveness of angling trips to changes in catch rates may vary because of differences in user populations, environmental conditions, fish populations, and fishing experiences.     

Steady streaming of viscous surface layer in waves

An investigation of the drift velocity induced by water waves of a contminated surface layer is carried out. The theoretical analysis is based on a thin boundary layer on the free surface. The results of the analysis reveal that the drift velocity of a viscous layer on the water surface is 7/4 times the Stokes prediction ofc(ak) ² wherec is the wave celerity andak the wave slope. The present experimental investigation confirms the validity of the theoretical prediction for the drift velocity for a lightly contaminated surface layer; however, for a heavily contaminated surface layer, the experimental results exceed the theoretical prediction. An investigation for a heavily contaminated layer is carried out assuming an inextensible surface layer. Thus, in the experiment, vinyl sheets are used to substitute the contaminated layers. By balancing the wave-induced mean thrust force with the mean drag force, the drift velocity is obtained and compared with the experimental results. Based on the theoretical and experimental analyses, formulae for predicting the drift velocities for laminar and turbulent flow conditions are proposed.     

Monitoring and modeling of coastal waters in support of environmental preservation

The improved monitoring and modeling capability resulting from recent technological advances in oceanographic sensors, computer processing power, and telecommunications can play a major role in environmental preservation. In particular, this capability can help improve: safe navigation and thus the prevention of maritime accidents that lead to hazardous spills; the effective cleanup of hazardous spills when they do occur; the real-time assessment of water quality problems; the assessment of long-term trends and variability due to both anthropogenic and climate change effects; and the understanding of key physical, chemical, and ecological processes. Presented at the International Conference on Technologies for Marine Environment Preservation (MARIENV’95), Tokyo, Japan, September 24–29, 1995     

山区河流航道整治施工对水生态环境的影响

山区河流航道整治一般采取筑坝、疏浚、炸礁、护岸等工程，在施工中不可避免对现状水生态环境造成扰动。以岷江下游航道整治一期工程为例，通过对代表性河段施工前后的水质、浮游生物、底栖动物、鱼类等种类和资源量开展现场监测，研究发现：施工前后水体化学需氧量、五日生化需氧量、氨氮、总磷、石油类、悬浮物的浓度有所升高，但均未超过相关标准限定值；藻类、水生维管束植物、浮游动物、底栖动物、鱼类等施工前后无明显减少。因此通过合理的时间、空间的施工避让，航道整治施工对山区河流水生态环境的影响较小。     

The Impact of Recreation on Barrier Islands: A Case Study on Masonboro Island

Since 1992, coastal researchers at the University of North Carolina at Wilmington have been documenting the impacts of human recreational use on Masonboro Island, a component of the North Carolina National Estuarine Research Reserve, and the subsequent natural processes that mitigate these impacts. Both short-term and long-term natural mitigational processes were identified. The effects of these processes were found to be much more rapid than similar impacts on typical terrestrial settings. However, careful examination of the data suggests that both physical location of the impact site and natural variability of weather patterns and events play a role. Management implications of these findings are proposed.