Marsh management plans in practice: Do they work in coastal Louisiana,USA?

Louisiana's coastal wetlands represent about 41% of the nation's total and are extensively managed for fish, fur, and waterfowl. Marsh management plans (MMPs) are currently used to avoid potential user conflicts and are believed to be a best management practice for specific management goals. In this article, we define MMPs and examine their variety, history, impacts, and future.A MMP is an organized written plan submitted to state and federal permitting agencies for approval and whose purpose is to regulate wetland habitat quantity and quality (control land loss and enhance productivity). MMPs are usually implemented by making structural modifications in the marsh, primarily by using a variety of water control structures in levees to impound or semi-impound managed areas. It appears that MMPs using impoundments are only marginally successful in achieving and often contradict management goals. Although 20% of coastal Louisiana may be in MMPs by the year 2000, conflict resolution of public and private goals is compromised by a surfeit of opinion and dearth of data and experience. Based on interpretation of these results, we believe the next phase of management should include scientific studies of actual impacts, utilization of post-construction monitoring data, inventory of existing MMPs, development of new techniques, and determination of cumulative impacts.     

The firm,environmental management and environmental measures: Lessons from a survey of European manufacturing firms

This paper reports on the results of a survey of environmental management and technical measures amongst almost 2000 European firms. Logit analysis is undertaken to determine the effects of firm characteristics, commercial conditions, perceived environmental impacts, expected benefits and stakeholder pressures on the probability of having an environmental management system in place. Subsequently, determinants of the likelihood of undertaking environmental actions in five environmental areas are estimated. There is a positive effect of environmental management on the likelihood of undertaking technical measures to reduce environmental impacts in some (but not all) areas, as well as a positive role for integrated environmental management strategies.     

Evaluation of methods for determining adverse impacts of air pollution on terrestrial ecosystems

Methods used to determine adverse impacts of air pollution on four levels of biological organization of terrestrial ecosystems were evaluated for their use in decision making by federal land managers of class I areas and as guidelines for scientists employed to design field studies in these areas. At the level of the individual, visible injury, biomass, and sulfur uptake were the most often used components; at the population level, natality and mortality; at the community level, diversity; and at the ecosystem level, biogeochemical cycling. Most studies focused on structural responses of individual organisms. These components are relatively sensitive and are easy and inexpensive to measure; however, linkages of these parameters to adverse impacts on populations, communities, or ecosystems are lacking. Measurements of effects of air pollution at the higher levels of organization are confounded by natural variability, long response times, climatic variation, pathogens, and other factors. In addition, the lack of replication and of true control areas creates severe problems for design of monitoring programs and testing of hypotheses concerning effects.     

Bird Use of Restoration and Reference Marshes Within the Barn Island Wildlife Management Area, Stonington, Connecticut, USA

/ Tidal marshes have been actively restored in Connecticut for nearly 20 years, but evaluations of these projects are typically based solely on observations of vegetation change. A formerly impounded valley marsh at the Barn Island Wildlife Management Area is a notable exception; previous research at this site has also included assessments of primary productivity, macroinvertebrates, and use by fishes. To determine the effects of marsh restoration on higher trophic levels, we monitored bird use at five sites within the Barn Island complex, including both restoration and reference marshes. Use by summer bird populations within fixed plots was monitored over two years at all sites. Our principal focus was Impoundment One, a previously impounded valley marsh reopened to full tidal exchange in 1982. This restoration site supported a greater abundance of wetland birds than our other sites, indicating that it is at least equivalent to reference marshes within the same system for this ecological function. Moreover, the species richness of birds and their frequency of occurrence at Impoundment One was greater than at 11 other estuarine marshes in southeastern Connecticut surveyed in a related investigation. A second marsh, under restoration for approximately ten years, appears to be developing in a similar fashion. These results complement previous studies on vegetation, macroinvertebrates, and fish use in this system to show that, over time, the reintroduction of tidal flooding can effectively restore important ecological functions to previously impounded tidal marshes.KEY WORDS: Estuarine; Tidal marsh; Wetland birds; Restoration     

Managing Radioactively Contaminated Land: Implications for Habitat Diversity

Radioactive contamination of agricultural land may necessitate long-term changes in food production systems, through application of selected countermeasures, in order to reduce the accumulation of radionuclides in food. We quantified the impact of selected countermeasures on habitat diversity, using the hypothetical case of two agricultural areas in Finland. The management scenarios studied were conversions from grassland to cereal production and from grassland and crop production to afforestation. The two study sites differed with respect to present agricultural production: one being predominantly cereal production and seminatural grasslands, while the other was dominated by intensive grass and dairy production. Some of the management scenarios are expected to affect landscape structures and habitat diversity. These potential changes were assessed using a spatial pattern analysis program in connection with geographic information systems. The studied landscape changes resulted in a more monotonous landscape structure compared to the present management, by increasing the mean habitat patch size, reducing the total habitat edge length and reducing the overall habitat diversity calculated by the Shannon diversity index. The degree of change was dependent on the present agricultural management practice in the case study sites. Where dairy production was predominant, the landscape structure changes were mostly due to conversion of intensive pastures and grasslands to cereal production. In the area dominated by cereal production and seminatural grasslands, the greatest predicted impacts resulted from afforestation of meadows and pastures. The studied management changes are predicted to reduce biodiversity at the species level as well as diminishing species-rich habitats. This study has predicted prominent side effects in habitat diversity resulting from application of management scenarios. These potential long-term impacts should be considered by decision-makers when planning future strategies in the event of radionuclide deposition.     

Hydrologic modeling as a predictive basis for ecological restoration of salt marshes

Roads, bridges, causeways, impoundments, and dikes in the coastal zone often restrict tidal flow to salt marsh ecosystems. A dike with tide control structures, located at the mouth of the Herring River salt marsh estuarine system (Wellfleet, Massachusetts) since 1908, has effectively restricted tidal exchange, causing changes in marsh vegetation composition, degraded water quality, and reduced abundance of fish and macroinvertebrate communities. Restoration of this estuary by reintroduction of tidal exchange is a feasible management alternative. However, restoration efforts must proceed with caution as residential dwellings and a golf course are located immediately adjacent to and in places within the tidal wetland. A numerical model was developed to predict tide height levels for numerous alternative openings through the Herring River dike. Given these model predictions and knowledge of elevations of flood-prone areas, it becomes possible to make responsible decisions regarding restoration. Moreover, tidal flooding elevations relative to the wetland surface must be known to predict optimum conditions for ecological recovery. The tide height model has a universal role, as demonstrated by successful application at a nearby salt marsh restoration site in Provincetown, Massachusetts. Salt marsh restoration is a valuable management tool toward maintaining and enhancing coastal zone habitat diversity. The tide height model presented in this paper will enable both scientists and resource professionals to assign a degree of predictability when designing salt marsh restoration programs.     

Evaluation of the Impacts of Dock Structures and Land Use on Tidal Creek Ecosystems in South Carolina Estuarine Environments

Tidal creeks and their associated salt marshes are the primary link between uplands and estuaries in the southeastern region. They are also critical nursery and feeding grounds. In addition, the uplands surrounding creeks are preferred sites for homebuilding because of their natural beauty and the ability to access the estuary from a personal dock structure. The objective of this study was to evaluate the cumulative impacts of docks on tidal creek nursery habitats for both small and large tidal creeks. The number of docks was associated with the amount of impervious cover in both small and large creeks. The presence of docks had little measurable effect on sediment metal concentrations at the scale of small and large creeks. In small and large creeks, sediment polycyclic aromatic hydrocarbon (PAH) concentrations were related to the human activity in the upland that includes the presence of docks at the scale of small and large creeks. Some impacts on the benthic community were associated with docks and human activity in small creeks but not in large creeks. Suburban development may reduce fish and crustacean abundances, but the dock may potentially mediate the development effect. Individually, the harm to the marine environment resulting from dock shading, chrominated copper arsenate leachates, and PAH contamination was small at the scale of tidal creeks. However, impacts from dock structures could not be separated from anthropogenic watershed-scale effects. These results demonstrate that suburban development with its accompanying dock construction does represent a major source of environmental degradation to tidal creeks and associated salt marsh habitats.     

Effects of Bridge Shading on Estuarine Marsh Benthic Invertebrate Community Structure and Function

The effect of bridge shading on estuarine marsh food webs was assessed by comparing benthic invertebrate communities beneath seven highway bridges with marshes outside of bridge-affected areas (reference marshes). We used light attenuation and height–width ratio (HW ratio), which takes into account the two main bridge characteristics that determine the degree of shading, to quantify the impact of shading on invertebrate communities. Low bridges, with HW ratio <0.7 and light attenuation greater than 85–90%, had benthic invertebrate densities and diversity that were significantly lower than reference marshes. Density of benthic invertebrates at low bridges was 25–52% (29,685–72,920 organisms/m²) of densities measured in adjacent reference marshes (119,329–173,351 organisms/m²). Likewise, there were fewer taxa under low bridges (5.8/11.35 cm² core) as compared to the reference marshes (9.0/11.35 cm² core). Density of numerically dominant taxa (e.g., oligochaetes and nematodes) as well as surface- and subsurface deposit feeders also were reduced under low bridges. Decreased invertebrate density, diversity, dominant taxa, and alterations of trophic feeding groups beneath low bridges was correlated with diminished above- and below-ground macrophyte biomass that presumably resulted in fewer food resources and available refuges from predators. With a greater knowledge of bridge shading effects, bridge construction and design may be improved to reduce the impacts on estuarine benthic invertebrate communities and overall ecosystem structure and function.     

Environmental occurrences, behavior, fate, and ecological effects of nanomaterials: an introduction to the special series

The release of engineered nanomaterials (ENMs) into the biosphere will increase as industries find new and useful ways to utilize these materials. Scientists and engineers are beginning to assess the material properties that determine the fate, transport, and effects of ENMs; however, the potential impacts of released ENMs on organisms, ecosystems, and human health remain largely unknown. This special collection of four review papers and four technical papers identifies many key and emerging knowledge gaps regarding the interactions between nanomaterials and ecosystems. These critical knowledge gaps include the form, route, and mass of nanomaterials entering the environment; the transformations and ultimate fate of nanomaterials in the environment; the transport, distribution, and bioavailability of nanomaterials in environmental media; and the organismal responses to nanomaterial exposure and effects of nanomaterial inputs, on ecological communities and biogeochemical processes at relevant environmental concentrations and forms. This introductory section summarizes the state of knowledge and emerging areas of research needs identified within the special collection. Despite recent progress in understanding the transport, transformations, and fate of ENMs in model environments and organisms, there remains a large need for fundamental information regarding releases, distribution, transformations and persistence, and bioavailability of nanomaterials. Moreover, fate, transport, bioaccumulation, and ecological impacts research is needed using environmentally relevant concentrations and forms of ENMs in real field materials and with a broader range of organisms.     

Wetland development trends in coastal North Carolina,USA, from 1970 to 1984

Coastal wetlands are a valuable resource to North Carolina, USA, representing important habitat for marine organisms and providing flood control areas and buffer zones from marine storms. An analysis of wetland development trends in coastal North Carolina from 1970 to 1984 was conducted using over 3000 files containing 15 years of permitting records. The total amount of coastal wetland area altered due to authorized development under the Coastal Area Management Act (CAMA), the Dredge and Fill Law, and Section 404 of the Federal Water Pollution Control Act is 1740 ha. This represents nearly 2% of the salt marsh wetlands along the coast of North Carolina. The number of permits issued steadily increased during the 1980s; however, the total amount of wetland loss decreased each year. A few large projects in the early 1970s accounted for nearly 70% of all wetland area developed during the 15-year period. Nearly two-thirds of all projects involving wetland destruction involved impacts on high marsh ecosystems. Bulkheads, canals, and filling activities made up 80% of the projects requiring permits; 62% of the permits were issued to private landowners, but this group accounted for only 16% of the losses of wetland area. Utility companies, which accounted for less than 1% of the permits issued, were responsible for 46% of the permitted wetland loss during the 15-year study period. Future studies should address agriculture and forestry practices which are exempt under CAMA laws and therefore their effects on wetland alteration have not been quantified.     

Adapting to Climate Change on Western Public Lands: Addressing the Ecological Effects of Domestic, Wild, and Feral Ungulates

Climate change affects public land ecosystems and services throughout the American West and these effects are projected to intensify. Even if greenhouse gas emissions are reduced, adaptation strategies for public lands are needed to reduce anthropogenic stressors of terrestrial and aquatic ecosystems and to help native species and ecosystems survive in an altered environment. Historical and contemporary livestock production—the most widespread and long-running commercial use of public lands—can alter vegetation, soils, hydrology, and wildlife species composition and abundances in ways that exacerbate the effects of climate change on these resources. Excess abundance of native ungulates (e.g., deer or elk) and feral horses and burros add to these impacts. Although many of these consequences have been studied for decades, the ongoing and impending effects of ungulates in a changing climate require new management strategies for limiting their threats to the long-term supply of ecosystem services on public lands. Removing or reducing livestock across large areas of public land would alleviate a widely recognized and long-term stressor and make these lands less susceptible to the effects of climate change. Where livestock use continues, or where significant densities of wild or feral ungulates occur, management should carefully document the ecological, social, and economic consequences (both costs and benefits) to better ensure management that minimizes ungulate impacts to plant and animal communities, soils, and water resources. Reestablishing apex predators in large, contiguous areas of public land may help mitigate any adverse ecological effects of wild ungulates.     

Predicting the Impacts of Future Sea-Level Rise on an Endangered Lagomorph

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-level rise to threatened and endangered species. Therefore, we estimated the impacts of rising sea levels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-level rise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-level rise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.     

An evaluation of the impact of persistent water level changes on the areal extent of Georgian Bay/North Channel marshlands

A conceptual mathematical model has recently been devised to assist environmental managers in predicting the impact on coastal marsh areas of long-term changes in water levels. The model considers such impact solely in terms of the geometry of the confining basin, the change in ambient water level, and the maximum depth for which bottom-rooted emergent vegetation is present. This model is applied to 17 shoreline marshes of various shapes in the Georgian Bay/North Channel region of the Great Lakes.Model outputs of predicted maximum and minimum marsh area subsequent to changes in long-term levels are compared to marsh areas measured from available historical air photos dating from 1935 to 1985. The results of such comparisons indicate that such a geometric model, despite its neglect of the biological complexities of marsh ecology, can serve as a valuable tool for assessing the range of impacts of both natural and man-made changes in long-term ambient water levels on shoreline marshes.     

Communicative Aspects of Environmental Management by Objectives: Examples from the Swedish Context

Management by objectives (MBO) is a technique for integrating ecological concerns into national political and administrative structures. Politicians determine environmental objectives and interim targets to be implemented and assessed by civil servants in national, regional, and local contexts. Well-developed organizational communication is a prerequisite for MBO. However, communication-related obstacles can arise when using MBO in public environmental management. We examine communicative aspects of environmental MBO, looking specifically at the implementation, administration, and assessment of Swedish environmental quality objectives. Our argument is illustrated by quotations from individual and focus group interviews. We conclude that communicative problems may arise, because different actors interpret messages from different perspectives, depending on their agendas, prior knowledge and experience, and positions in the administrative system. It is crucial to recognize the dialogical aspects of communication, by involving the receiver of a message in a process of response. In addition, the different timeframes underlying different arguments could contribute to misunderstandings between actors involved in handling environmental issues. In assessing the achievement of environmental objectives, indicators are used as communicative tools. It is important to investigate whether and how these indicators contribute to the de- and recontextualization of environmental objectives.     

Strategic Environmental Assessment of the Effects of European Union's Regional Development Plans in Doñana National Park (Spain)

The European Union's Structural Funds are implemented by means of Regional Development Plans (RDP), whose regionally scoped environmental assessment is required. We highlight the deficiencies faced by this approach when subregional areas with high conservation natural values are involved and illustrate it with the case of the RDP of Andalusia region on Doñana National Park area (Spain). Commissioned by the World Wildlife Fund, a Strategic Environmental Assessment (SEA) of the Andalusian RDP was carried out focusing on Doñana and its area of influence. This is a complex space where some of the most environmentally valuable features in the continent coexist with a surrounding intense and multi-sector economic activity, threatening its conservation. In the absence of an established sustainability framework in the Region, a “trickle-down” SEA approach evidenced the need to produce a set of environmental, economic and social guidelines for sustainable management of land, against which the RDP objectives were tested for coherence. An “incremental” SEA approach was also tested, which involved the identification of 79 measures and actions stemming from the RDP provisions and other concurrent planning documents reviewed and the qualitative assessment of their individual and cumulative potential impacts on Doñana environments. In the light of the results, a set of complementary mitigating measures was proposed for inclusion in tiered stages of the planning process. Measures to avoid, reduce, remedy and monitor the major types of impact were proposed, including provisions for public participation. SEA emerges as an instrument for non-governmental organizations (NGOs) to carry out independent assessment of public development initiatives.     

Plant Community Composition and Biomass in Gulf Coast Chenier Plain Marshes: Responses to Winter Burning and Structural Marsh Management

Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands. Although management practices are intended to influence the plant community, effects of these practices on primary productivity have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics (species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes, such as vertical accretion, that are dependent on organic matter accumulation and decay.     

Using secondary data to analyse socio-economic impacts of water management actions

This paper provides an analysis of the socio-economic impacts of river restoration schemes, and is novel in considering how a wide range of socio-economic variables can be used to understand impacts on the entire resident population within an area. A control-impacted approach was applied to explore differences in socio-economic characteristics of areas within which a restoration scheme had been carried out compared to areas without such a scheme. The results show that significant differences exist between control and impacted areas for a range of socio-economic variables. However, due to constraints in the methods and the data available, there are currently limitations in the extent to which socio-economic impacts of river restoration schemes can be fully explored. Additional datasets that become available in the future may increase the ability to detect associations between improvements in the water environment and socio-economic benefits. However, whilst the secondary data used in this paper are potentially powerful, they should be used alongside other techniques for assessing the impacts of decisions as part of future frameworks to deliver sustainable water management.     

Quantitative Assessment of the Intertidal Environment of Kuwait I: Integrated Environmental Classification

Quantitative analysis of physical, chemical and biological data of the intertidal zone in Kuwait was undertaken to develop an integrated basis for assessing and protecting this sensitive coastal ecosystem. Cluster analyses were performed to determine the resemblance between the sampling stations based on the sediment composition, the benthic macrofauna and the physico-chemical characteristics of the intertidal sediment/water. Five distinct sub-environments were delineated within the intertidal zone of Kuwait. Each sub-environment was described in terms of number of taxa, mean density of organisms, sediment type, tidal level and dominant organisms. The physico-chemical parameters investigated were found to be unimportant in the distribution of the intertidal benthic macrofauna. On the other hand, sediment type was found to be a major factor in the overall composition of the benthic community. The benthic fauna and related characteristics of the sub-environments could be used as indicators to monitor changes in the intertidal ecosystem and as guides to protection and management of the different coasts. The approach described in this paper could also be adopted elsewhere to provide a sound basis for evaluating environmental impacts and for developing sustainable coastal management.     

Effects of power-line construction on wetland vegetation in Massachusetts,USA

Utility rights-of-way corridors through wetland areas generate long-term impacts from construction activities to these valuable ecosystems. Changes to and recovery of the vegetation communities of a cattail marsh, wooded swamp, and shrub/bog wetland were documented through measurements made each growing season for two years prior, five years following, and again on the tenth year after construction of a 345-kV transmission line. While both the cattail marsh and wooded swamp recovered within a few years, measures of plant community composition in the shrub/bog wetland were still lower, compared to controls, after ten years. Long-term investigations such as the one reported here help decrease uncertainty and provide valuable information for future decision making regarding construction of power utility lines through valuable and dwindling wetland resources.