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PubMed2002

The US Clean Water Act and habitat replacement: evaluation of mitigation sites in Orange County, California, USA.

Both permit requirements and ecological assessments have been used to evaluate mitigation success. This analysis combines these two approaches to evaluate mitigation required under Section 404 of the United States Clean Water Act (CWA) and Section 10 of the Rivers and Harbors Act, which allow developers to provide compensatory mitigation for unavoidable impacts to wetlands. This study reviewed permit files and conducted field assessments of mitigation sites to evaluate the effectiveness of mitigation required by the US Army Corps of Engineers for all permits issued in Orange County, California from 1979 through 1993. The 535 permit actions approved during this period allowed 157 ha of impacts. Mitigation was required on 70 of these actions, with 152 ha of enhanced, restored, and created habitat required for 136 ha of impacts. In 15 permit actions, no mitigation project was constructed, but in only two cases was the originally permitted project built; the two cases resulted in an unmitigated loss of 1.6 ha. Of the remaining 55 sites, 55% were successful at meeting the permit conditions while 11% failed to do so. Based on a qualitative assessment of habitat quality, only 16% of the sites could be considered successful and 26% were considered failures. Thus, of the 126 ha of habitat lost due to the 55 projects, only 26 ha of mitigation was considered successful. The low success rate was not due to poor enforcement, although nearly half of the projects did not comply with all permit conditions. Mitigation success could best be improved by requiring mitigation plans to have performance standards based on habitat functions.

California↗
PubMed2003

Wetland mitigation compliance in the western upper peninsula of Michigan.

The Army Corps of Engineers (ACE) is generally responsible for the implementation of federal Clean Water Act wetland regulations. It therefore plays an important role in the protection of wetlands within the United States. Unfortunately, past evaluators of ACE's implementation of these regulations found low rates of regulatory compliance. However, the fact that two states have taken responsibility for the implementation of these regulations within their boundaries provided the opportunity to assess whether one of these states might be doing a better job of enforcement. This paper reports on compliance with some of these regulations within one Michigan region. We evaluated permittee compliance with paperwork filing requirements related to wetland mitigation projects. Sixty-seven percent of county road commission permittees were out of compliance with at least one filing requirement. Forty percent of private and non-county government permittees were out of compliance. Our results therefore suggest that serious problems exist with Michigan's implementation of wetland regulations. They do not suggest that compliance in this state is significantly better than in states under ACE administration. We believe that increased agency monitoring and enforcement would improve compliance.

Conservation of Natural Resources↗
PubMed2004

Wetland ecological and compliance assessments in the San Francisco Bay Region, California, USA.

The San Francisco Bay Region of the California Regional Water Quality Control Board (SFB CRWQCB) and the San Francisco District of the US Army Corps of Engineers (US ACOE) are looking for an expeditious means to determine whether regulated wetland projects produce ecologically valuable systems and remain in compliance with their permits (i.e. fulfill their legal requirements) until project completion. A study was therefore undertaken in which 20 compensatory wetland mitigation projects in the San Francisco Bay Region were reviewed and assessed for both permit compliance and habitat function, and this was done using a rapid assessment method adapted for this purpose. Thus, in addition to determining compliance and function, a further goal of this study was to test the efficacy of the assessment method, which, if useful, could be applied not only to mitigation projects, but also to restoration projects and natural wetland systems. Survey results suggest that most projects permitted 5 or more years ago are in compliance with their permit conditions and are realizing their intended habitat functions. The larger restoration sites or those situated between existing wetland sites tend to be more successful and offer more benefits to wildlife than the smaller isolated ones. These results are consistent with regulatory experience suggesting that economies of scale could be realized both with (1) large scale regional wetland restoration sites, through which efforts are combined to control invasive species and share costs, and (2) coordinated efforts by regulatory agencies to track project information and to monitor the increasing number and size of mitigation and restoration sites. In regard to the assessment methods, we find that their value lies in providing a consistent protocol for evaluations, but that the ultimate assessment will rely heavily on professional judgment, regulatory experience, and the garnering of pre-assessment information.

Animals↗
PubMed2006

Environmental analysis in the selection of alternative corridors in a long-distance linear project: a methodological proposal.

A linear engineering project--i.e. a pipeline--has a potential long- and short-term impact on the environment and on the inhabitants therein. We must find better, less expensive, and less time-consuming ways to obtain information on the environment and on any modifications resulting from anthropic activity. We need scientifically sound, rapid and affordable assessment and monitoring methods. Construction companies, industries and the regulating government organisms lack the resources needed to conduct long-term basic studies of the environment. Thus there is a need to make the necessary adjustments and improvements in the environmental data considered useful for this development project. More effective and less costly methods are generally needed. We characterized the landscape of the study area, situated in the center and north-east of Argentina. Little is known of the ecology of this region and substantial research is required in order to develop sustainable uses and, at the same time, to develop methods for reducing impacts, both primary and secondary, resulting from anthropic activity in this area. Furthermore, we made an assessment of the environmental impact of the planned linear project, applying an ad hoc impact index, and we analyzed the different alternatives for a corridor, each one of these involving different sections of the territory. Among the alternative corridors considered, this study locates the most suitable ones in accordance with a selection criterion based on different environmental and conservation aspects. We selected the corridor that we considered to be the most compatible--i.e. with the least potential environmental impact--for the possible construction and operation of the linear project. This information, along with suitable measures for mitigating possible impacts, should be the basis of an environmental management plan for the design process and location of the project. We pointed out the objectivity and efficiency of this methodological approach, along with the possibility of integrating the information in order to allow for the application thereof in this type of study.

Argentina↗
PubMed2002

Determining ecological equivalence in service-to-service scaling of salt marsh restoration.

The amount of ecological restoration required to mitigate or compensate for environmental injury or habitat loss is often based on the goal of achieving ecological equivalence. However, few tools are available for estimating the extent of restoration required to achieve habitat services equivalent to those that were lost. This paper describes habitat equivalency analysis (HEA), a habitat-based "service-to-service" approach for determining the amount of restoration needed to compensate for natural resource losses, and examines issues in its application in the case of salt marsh restoration. The scientific literature indicates that although structural attributes such as vegetation may recover within a few years, there is often a significant lag in the development of ecological processes such as nutrient cycling that are necessary for a fully functioning salt marsh. Moreover, natural variation can make recovery trajectories difficult to define and predict for many habitat services. HEA is an excellent tool for scaling restoration actions because it reflects this ecological variability and complexity. At the same time, practitioners must recognize that conclusions about the amount of restoration needed to provide ecological services equivalent to those that are lost will depend critically on the ecological data and assumptions that are used in the HEA calculation.

Conservation of Natural Resources↗
PubMed2002

Macroinvertebrate and fish populations in a restored impounded salt marsh 21 years after the reestablishment of tidal flooding.

During the last two decades, the State of Connecticut has restored tidal flow to many impounded salt marshes. One of the first of these and the one most extensively studied is Impoundment One in the Barn Island Wildlife Management Area in Stonington, Connecticut. In 1990, twelve years after the re-establishment of tidal flooding, the density of the marsh snail Melampus bidentatus, the numerically dominant macroinvertebrate of the high marsh, in Impoundment One was about half that in reference marshes below the breached impoundment dike. By 1999 the densities of Melampus above and below the dike were not significantly different, but the shell-free biomass was greater above the dike as a result of the somewhat larger number and size of the snails there. Twenty-one years after the renewal of tidal flooding, three marsh macroinvertebrates (the amphipods Orchestia grillus and Uhlorchestia spartinophila and the mussel Geukensia demissa) were significantly less abundant in the previously impounded marsh than in the reference marshes, whereas another amphipod (Gammarus palustris) was more abundant above the breached dike where conditions appeared to be somewhat wetter. In 1991 the fish assemblage in a mosquito-control ditch in Impoundment One was similar to that in a ditch below the breached dike; however, the common mummichog Fundulus heteroclitus appeared to be less abundant in the restoring marsh. By 1999 the number of mummichogs caught in ditches was significantly greater in Impoundment One than in the reference marsh, but the numbers of mummichogs trapped along the tidal creek were comparable above and below the dike. The results obtained in this study and those of other restoring marshes at Barn Island indicate the full recovery of certain animal populations following the reintroduction of tidal flow to impounded marshes may require up to two or more decades. Furthermore, not only do different species recover at different rates on a single marsh, but the time required for the recovery of a particular species may vary widely from marsh to marsh, often independently of other species.

Animals↗
PubMed2002

Impacts of man-made landscape features on numbers of estuarine waterbirds at low tide.

The potential impact of human disturbance on wintering waterbirds using intertidal mudflats was considered by relating their numbers to the presence of nearby footpaths, roads, railroads, and towns. Data were obtained for six English estuaries from the Wetland Bird Survey Low Tide Count scheme. Counts were undertaken monthly from November to February, and data were available for an average of 2.8 years per estuary for the period 1992-1993 to 1999-2000. Count sections and the positions of man-made landscape features were mapped using a GIS. Generalized linear models tested whether bird numbers varied according to the estuary, month, area, whether or not the section bordered water, and the proportion of each section within a specified distance of each landscape feature. In addition, the proximity of sections to the nearest footpath access point was considered. Numbers of six of nine species, northern shelduck (Tadorna tadorna), red knot (Calidris canutus), dunlin (Calidris alpina), black-tailed godwit (Limosa limosa), Eurasian curlew (Numenius arquata) and common redshank (Tringa totanus), were significantly lower where a footpath was close to a count section, while those of brant (Branta bernicla) were greater. Northern shelduck, black-bellied plover (Pluvialis squatarola), dunlin, and black-tailed godwit numbers were reduced close to railroads and those of common ringed plover (Charadrius hiaticula), black-bellied plover, and Eurasian curlew close to roads. Common ringed plover numbers were greater close to towns. The relative distances to which species were affected by footpaths corresponded to published information concerning their flight distances in response to human disturbance. The study provided evidence that sustained disturbance associated with footpaths, roads, and railroads reduced local habitat quality for waterbirds and the carrying capacity of estuaries.

Animals↗
PubMed2005

Evaluating the risk of potential acid sulfate soils and habitat modification for mosquito control (runneling) in coastal salt marshes: comparing methods and managing the risk.

Coastal environments in Australia are under development pressures. Human settlement encroaches on disease vector salt marsh mosquito breeding areas that are underlain by potential acid sulfate soils (PASS). Altering the hydrology by runneling solves the mosquito problem but may lead to acid sulfate problems. Appropriate analytical tools can assess the risk to the environment. The objective of the research was to compare three methods of assessing PASS. The study area was a low-lying intertidal subtropical salt marsh that was being considered for runneling. The results indicated that using field pH and field peroxide pH (and the relationship between these), and also the peroxide oxidation-combined acidity and sulfate (POCAS) test, appeared to overestimate the potential acidity. This was because the source of acidity in the intertidal salt marsh includes a large organic content, which is not a major environmental concern. The chromium-reducible sulfur test, which is not affected by organic content, was found to provide the most appropriate assessment, and is recommended for use in highly organic salt marshes.

Ecosystem↗
PubMed2004

Adverse effects on Alfeios River Basin and an integrated management framework based on sustainability.

The Alfeios River, the longest and highest flow-rate river in Peloponnisos, constitutes an important water resource and ecosystem in Greece. In the present study, human activities in the Alfeios River Basin are described, and their impacts on water quality and the ecosystem are analyzed; effects resulting from interventions on river geomorphology between Flokas Dam and the river delta are determined. These actions have caused significant adverse impacts on the infrastructure (the dam, railroad, and road bridges), the level of aquifer water table and area water uses, and the aquatic and riparian ecosystem. A general integrated management strategy is formulated and a master management plan is proposed for resolving management problems in river basins. The plan considers local conditions and national requirements and complies with the European Communities legislation; it would help prevent further basin deterioration, improve water quality, and protect water resources and ecosystems in the area in accordance to sustainable development. The Alfeios River Basin serves as a case study in the development of the plan.

Agriculture↗
PubMed2003

The roles and limitations of newspapers in environmental reporting. Case study: Isahaya Bay land reclamation project issue.

This paper looks at Japanese newspaper coverage of environmental issues, focusing on the case of the controversy over the Isahaya Bay land reclamation project. This project was first planned in the early 1950s and construction began in 1989. Local activists groups began raising questions about the project in the 1970s, focusing on the environmental degradation that would result, but they did not succeed in having their opinions discussed widely in the media until it was too late to prevent completion. Only after the dramatic images of the last slab of the seawall falling into place, was there intense media coverage of the project. The attention paid to the project by the media did much to inform the public about the effects of large-scale public works projects on the environment. Yet an analysis of the newspaper coverage shows that the media played mostly a "spectator" role in the controversy, merely reacting to events. A more active, "watch-dog" role would be necessary for the media to uncover threats to the environment in time for the public to be educated about such issues and have a chance to influence crucial official decisions.

Community Participation↗
PubMed2003

Dredging-induced nutrient release from sediments to the water column in a southeastern saltmarsh tidal creek.

Dredging is a large-scale anthropogenic disturbance agent in coastal and estuarine habitats that can profoundly affect water quality. We examined the impact of a small-scale dredging operation in a salt marsh in South Carolina by comparing nutrient levels (NH(4)(+), NO(x), PO(4)(-)) and total suspended solid concentrations before and during dredging activities. Nutrient enrichment was evaluated within the context of tidal, seasonal, and inter-annual variability by using long-term water chemistry data provided by the North Inlet-Winyah Bay National Estuarine Research Reserve. The conditions of the dredging permit (i.e., its relatively small scale), the season chosen for the work (fall-winter), the nature of the sediments dredged (coarse-grained), and the amount of natural variability in the estuary's water chemistry (even on a daily time-scale) all minimized the impact of the dredging activities. Results of this study will add to the limited body of empirical data that should be considered in evaluating future dredging permit applications related to shallow estuarine waterways.

Ecosystem↗
PubMed2003

Diversion of water flow from a floodplain wetland stream: an analysis of geomorphological setting and hydrological and ecological consequences.

Diversion of water has been ongoing in the Mkuze Wetland for several decades. Two canals form the focus of this study; the Mpempe-Demazane Canal and the Tshanetshe Canal. The former involved an ambitious excavation over a distance of 13.5 km in the lower part of the wetland, while the latter was a minor excavation over a distance of approximately 100 m in the upper part of the wetland. Although ambitious and costly, the Mpempe-Demazane Canal resulted in little downward or headward erosion, and there was minor diversion of flow. However, the minor excavation of the Tshanetshe Canal resulted in erosion downstream of the excavation (the Tshanetshe Stream), downward and lateral erosion of the excavated section, and headward erosion that has propagated almost 4 km upstream along the Mkuze River. Most of the flow of the Mkuze River has been captured by the Tshanetshe Canal and Stream. The impact of canalisation on floodplain wetlands is thus more dependent on the location than the scale of activity. The avulsion of the Mkuze River into the Tshanetshe Canal and Stream is due to a large difference in elevation between the Mkuze River and floodplain into which it was diverted, and the fact that in this region the river typically has high discharges. This avulsion may have been inevitable as a result of natural processes of sedimentation. In contrast, the difference in elevation between the Mkuze River and the basin into which it was diverted via the Mpempe Canal was small as is discharge of the Mkuze River in this part of the wetland. Thus, the diversion was unsuccessful. The presence of hippos that create hydraulically efficient pathways that are oriented parallel to the regional hydraulic slope, may accelerate avulsion in large African wetlands. Overall, it is argued that the environmental consequences of excavation need to be viewed against the background that wetlands are dynamic features within the landscape.

Conservation of Natural Resources↗
PubMed1996

Bioaugmentation as a soil bioremediation approach.

The debate over the efficacy of bioaugmentation rages on, with research continuing to demonstrate that its advantages for soil bioremediation are difficult to predict; however, when it works, the results are often very encouraging. The difficulties arise from, among others, the diversity of the microorganisms used, environmental heterogeneity, and variations in the influence of critical parameters (e.g. humidity, microbial predation and "bioavailability') which, unfortunately, are not even always identified.

Biodegradation, Environmental↗
PubMed2004

Foliar concentrations of volunteer willows growing on polluted sediment-derived sites versus sites with baseline contamination levels.

Many alluvial soils along navigable waterways are affected by disposal of dredged sediments or overbank sedimentation and contain metal concentrations that are elevated compared to baseline levels. Uptake patterns for metals and other elements by several volunteer Salix species growing on these sites were determined during a growing season in field plots and compared with the same species growing on soils with baseline contamination levels. For Cd and Zn, foliar concentrations were clearly higher on dredged sediment landfills. Uptake patterns differed significantly between species. A high uptake of Mn and low uptake of Cu, K and S in S. cinerea was attributed to wetland soil chemistry. Site effects on metal uptake were evaluated in more detail for Salix cinerea and S. alba growing on different sediment-derived sites under field conditions. Foliar Cd concentrations were higher in S. cinerea than in S. alba. This appeared to be a genetic feature not influenced by soil chemical properties, as it was observed both on clean sites and polluted sediment-derived sites. For S. cinerea, soil chemistry was reflected in foliar concentrations, while foliar Cd concentrations and bioavailability were found to be independent of the thickness of the polluted horizon. Dredged sediment landfills and freshwater tidal marshes with comparable Cd soil pollution had significantly different foliar Cd concentrations.

Ecosystem↗