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  Environmental Policy Issues

Wetlands:
History and Restoration Issues

(Released September 2003)

 

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  1. Residual Organochlorine Pesticides In Soils And Fish From Wetland Restoration Areas In Central Florida, USA

    Marburger, JE; Johnson, WE; Gross, TS; Douglas, DR; Di, J

    Wetlands [Wetlands]. Vol. 22, no. 4, pp. 705-711. Dec 2002.

    Four wetland restoration sites in the Emeralda Marsh Conservation Area located in central Florida, USA were flooded between 1992 and 1994. Florida Fish and Wildlife Conservation Commission stocked largemouth bass in the flooded areas from 1992 to 1996. In 1996, organochlorine pesticides (OCPs) were measured in flooded soils and in black crappie, brown bullhead catfish, and largemouth bass from the four sites. Areas 5 and 7 had the highest concentrations of total residual OCPs in the flooded soils, including dieldrin (385 plus or minus 241 mu g/kg), sum of DDT, DDD, and DDE (7,173 plus or minus 1,710 mu g/kg), and toxaphene (39,444 plus or minus 11,284 mu g/kg). Sum of chlordane residuals was highest in area 5 (1,766 plus or minus 1,037 mu g/kg). ANOVA indicated significant differences in location and fish muscle tissue concentrations for chlordane residuals, DDT residuals, and dieldrin. Fish from areas 5 and 7 had the greatest concentrations of chlordane residuals, DDT residuals, and dieldrin, which corresponded to the higher soil concentrations in these two areas. OCPs in muscle tissue were below the U.S. Food and Drug Administration action limits for human consumption. For three-year-old bass collected from Area 5, mean concentrations of chlordane residuals, DDT residuals, and dieldrin were 15-17 times higher in ovary tissue and 76-80 times higher in fat tissue compared with muscle tissue. Mean toxaphene levels in bass ovary and fat tissues were 9 and 39 times higher, respectively, than in muscle tissues. Tissue OCP concentrations were consistent with site OCPs, regardless of fish species.

  2. Using Functional Trajectories to Track Constructed Salt Marsh Development in the Great Bay Estuary, Maine/New Hampshire, U.S.A.

    Morgan, PA; Short, FT

    Restoration Ecology [Restor. Ecol.]. Vol. 10, no. 3, pp. 461-473. Sep 2002.

    A growing number of studies have assessed the functional equivalency of restored and natural salt marshes. Several of these have explored the use of functional trajectories to track the increase in restored marsh function over time; however, these studies have disagreed as to the usefulness of such models in long-term predictions of restored marsh development. We compared indicators of four marsh functions (primary production, soil organic matter accumulation, sediment trapping, and maintenance of plant communities) in 6 restored and 11 reference (matched to restored marshes using principal components analysis) salt marshes in the Great Bay Estuary. The restored marshes were all constructed and planted on imported substrate and ranged in age from 1 to 14 years. We used marsh age in a space-for-time substitution to track constructed salt marsh development and explore the use of trajectories. A high degree of variability was observed among natural salt marsh sites, displaying the importance of carefully chosen reference sites. As expected, mean values for constructed site (n = 6) and reference site (n = 11) functions were significantly different. Using constructed marsh age as the independent variable and functional indicator values as dependent variables, nonlinear regression analyses produced several ecologically meaningful trajectories (r super(2)> 0.9), demonstrating that the use of different-aged marshes can be a viable approach to developing functional trajectories. The trajectories illustrated that although indicators of some functions (primary production, sediment deposition, and plant species richness) may reach natural site values relatively quickly (<10 years), others (soil organic matter content) will take longer.

  3. Contrasting Functional Performance of Juvenile Salmon Habitat in Recovering Wetlands of the Salmon River Estuary, Oregon, U.S.A.

    Gray, A; Simenstad, CA; Bottom, DL; Cornwell, TJ

    Restoration Ecology [Restor. Ecol.]. Vol. 10, no. 3, pp. 514-526. Sep 2002.

    For an estuarine restoration project to be successful it must reverse anthropogenic effects and restore lost ecosystem functions. Restoration projects that aim to rehabilitate endangered species populations make project success even more important, because if misjudged damage to already weakened populations may result. Determining project success depends on our ability to assess the functional state or 'performance' and the trajectory of ecosystem development. Mature system structure is often the desired 'end point' of restoration and is assumed to provide maximum benefit for target species; however, few studies have measured linkages between structure and function and possible benefits available from early recovery stages. The Salmon River estuary, Oregon, U.S.A., offers a unique opportunity to simultaneously evaluate several estuarine restoration projects and the response of the marsh community while making comparisons with a concurring undiked portion of the estuary. Dikes installed in three locations in the estuary during the early 1960s were removed in 1978, 1987, and 1996, creating a 'space-for-time substitution' chronosequence. Analysis of the marsh community responses enables us to use the development state of the three recovering marshes to determine a trajectory of estuarine recovery over 23 years and to make comparisons with a reference marsh. We assessed the rate and pattern of juvenile salmon habitat development in terms of fish density, available prey resources, and diet composition of wild juvenile Oncorhynchus tshawytscha (chinook salmon). Results from the outmigration of 1998 and 1999 show differences in fish densities, prey resources, and diet composition among the four sites. Peaks in chinook salmon densities were greatest in the reference site in 1998 and in the youngest (1996) site in 1999. The 1996 marsh had higher densities of chironomids (insects; average 864/m super(2)) and lower densities of amphipods (crustaceans; average 8/m super(3)) when compared with the other sites. Fauna differences were reflected in the diets of juvenile chinook with those occupying the 1978 and 1996 marshes based on insects (especially chironomids), whereas those from the 1987 and reference marshes were based on crustaceans (especially amphipods). Tracking the development of recovering emergent marsh ecosystems in the Salmon River estuary reveals significant fish and invertebrate response in the first 2 to 3 years after marsh restoration. This pulse of productivity in newly restored systems is part of the trajectory of development and indicates some level of early functionality and the efficacy of restoring estuarine marshes for juvenile salmon habitat. However, to truly know the benefits consumers experience in recovering systems requires further analysis that we will present in forthcoming publications.

  4. Isolated Wetlands: Wisconsin Steps In with Regulations after Supreme Court Decision

    Anon.

    Coastal Services: Linking People, Information, and Technology [Coast. Serv.: Linking People, Inf., Technol.]. Vol. 5, no. 3, pp. 4-6. Jun 2002.

    A significant portion of the nation's wetlands were left unregulated last January after the U.S. Supreme Court ruled that the Clean Water Act does not give the federal government the authority to regulate "isolated" wetlands. In response to the ruling, Wisconsin was the first state to pass legislation to protect these vulnerable areas.

  5. Establishing aquatic restoration priorities using a watershed approach

    Bohn, B; Kershner, J

    Journal of Environmental Management [J. Environ. Manage.]. Vol. 64, no. 4, pp. 355-363. Apr 2002.

    Since the passage of the Clean Water Act in 1972, the United States has made great strides to reduce the threats to its rivers, lakes, and wetlands from pollution. However, despite our obvious successes, nearly half of the nation's surface water resources remain incapable of supporting basic aquatic values or maintaining water quality adequate for recreational swimming. The Clean Water Act established a significant federal presence in water quality regulation by controlling point and non-point sources of pollution. Point-sources of pollution were the major emphasis of the Act, but Section 208 specifically addressed non-point sources of pollution and designated silviculture and livestock grazing as sources of non-point pollution. Non-point source pollutants include runoff from agriculture, municipalities, timber harvesting, mining, and livestock grazing. Non-point source pollution now accounts for more than half of the United States water quality impairments. To successfully improve water quality, restoration practitioners must start with an understanding of what ecosystem processes are operating in the watershed and how they have been affected by outside variables. A watershed-based analysis template developed in the Pacific Northwest can be a valuable aid in developing that level of understanding. The watershed analysis technique identifies four ecosystem scales useful to identify stream restoration priorities: region, basin, watershed, and site. The watershed analysis technique is based on a set of technically rigorous and defensible procedures designed to provide information on what processes are active at the watershed scale, how those processes are distributed in time and space. They help describe what the current upland and riparian conditions of the watershed are and how these conditions in turn influence aquatic habitat and other beneficial uses. The analysis is organized as a set of six steps that direct an interdisciplinary team of specialists to examine the biotic and abiotic processes influencing aquatic habitat and species abundance. This process helps develop an understanding of the watershed within the context of the larger ecosystem. The understanding gained can then be used to identify and prioritize aquatic restoration activities at the appropriate temporal and spatial scale. The watershed approach prevents relying solely on site-level information, a common problem with historic restoration efforts. When the watershed analysis process was used in the Whitefish Mountains of northwest Montana, natural resource professionals were able to determine the dominant habitat forming processes important for native fishes and use that information to prioritize, plan, and implement the appropriate restoration activities at the watershed scale. Despite considerable investments of time and resources needed to complete an analysis at the watershed scale, the results can prevent the misdiagnosis of aquatic problems and help ensure that the objectives of aquatic restoration will be met. Copyright 2002 Academic Press

  6. Constraints of Seed Bank Species Composition and Water Depth for Restoring Vegetation in the Florida Everglades, U.S.A.

    Smith, SM; Mccormick, PV; Leeds, JA; Garrett, PB

    Restoration Ecology [Restor. Ecol.]. Vol. 10, no. 1, pp. 138-145. Mar 2002.

    The Rotenberger Wildlife Management Area (RWMA) is a northern Everglades marsh, in Florida, U.S.A., that will undergo hydrologic restoration to remedy an artificially shortened hydroperiod. In an effort to predict vegetation responses to the impending changes in hydrology, plant community development from the resident seed bank was observed in response to three different moisture regimes in March and September 1998. Percent cover, species densities, total seedling densities, and percentages of facultative, facultative-upland, and upland indicator species were significantly higher in moist than in saturated soils. Flooding inhibited the germination of all species except Typha domingensis (cattail), which emerged in the highest numbers from saturated soils in both assays. Lythrum alatum (purple loosestrife) was abundant in both saturated and moist conditions. The season of assay affected species densities and the communities. Percent facultative-wetland species increased in saturated soils in the March assay but not in September. In contrast, percent obligate hydrophytes were higher in saturated conditions only in the September assay. In general the assay communities bore little resemblance to vegetation in currently undisturbed or historic wetlands of the northern Everglades. Consequently the RWMA seed bank will contribute little to the development of a restored community. Moreover, rehydration may encourage the spread of undesirable hydrophytes such as T. domingensis . This study supports the contention that hydrologic restoration must be accompanied by some level of active vegetation management and that the reference condition cannot be attained passively.

  7. Integrated Management of Waterbird Habitats at Impounded Wetlands in Delaware Bay, U.S.A.

    Parsons, KC

    Waterbirds [Waterbirds]. Vol. 25, suppl. 2, pp. 25-41. 2002.

    Most streams in the upper Delaware Bay U.S.A. drainage have been impounded either historically or at present to accommodate a variety of wetland management objectives. Long-term impoundment has resulted in loss of wetland function and biodiversity. Nevertheless, extensive wetlands in Salem County, New Jersey and New Castle County, Delaware provide habitat for many important waterbirds, including breeding wading birds, migratory shorebirds, and waterfowl. Public and private agencies in both states have initiated wetland restoration programs to improve habitat values for multiple waterbird groups. I conducted wetland studies in nine streams to examine patterns of waterbird use to 1) identify water level management practices that promote waterbird utilization, and 2) develop guidelines for resource managers to meet integrated wetland management objectives. A total of 62 species (32,100 individuals) of wading birds, waterfowl, shorebirds, seabirds, marshbirds, and raptors was recorded April-July, 1993-1996 and 2000 during weekly observations. Most waterbird groups were more abundant at impounded sites than at tidal sites in streams. In addition, the use of streams within the region varied for all waterbird groups indicating that some streams were highly utilized while at others, relatively few waterbirds were present. Water level management regime was an important factor in determining waterbird use. Wading birds were most abundant at wetlands undergoing a mid-season drawdown at which time many locally-breeding species were meeting adult and nestling food requirements. Waterfowl were more abundant at wetlands with relatively high water levels in early spring compared to levels later in the season, which coincided with duck migration. Migratory shorebirds were most abundant on wetlands with relatively low water levels during May. Results 1) confirm the need for variably-managed wetland mosaics which provide habitat at a variety of water levels and 2) identify the importance of timing of drawdown in meeting the foraging needs of multiple waterbird groups.

  8. Wetland Conservation and Ducks Unlimited: Real World Approaches to Multispecies Management

    Tori, GM; McLeod, S; McKnight, K; Moorman, T; Reid, FA

    Waterbirds [Waterbirds]. Vol. 25, suppl. 2, pp. 115-121. 2002.

    Conversion and loss of coastal, riverine, and palustrine wetlands to agricultural, urban, and industrial developments have had significant impacts on waterbirds. Degradation of wetlands and associated upland habitats, and associated impacts on several duck and rail species are well documented. Wetland restoration and management are essential for wildlife diversity because of the magnitude of wetland destruction and hydrological modification that has occurred in most of the United States. Half of threatened and endangered species rely upon wetlands for some portion of their life cycle, underscoring the importance of wetlands to all wildlife. Ducks Unlimited, during its 65-year history of conservation programs, has restored, protected, and enhanced nearly 4.05 million hectares of wetlands and associated uplands in North America. Despite the accomplishments of Ducks Unlimited and its private, state, provincial and federal partners, the perception remains that our efforts benefit only waterfowl. However, wildlife inventories on Ducks Unlimited projects indicate benefits to more than 900 species. Herein, we promote an integrated, habitat-based landscape approach to wetland restoration and management, rather than individual species management, to achieve biodiversity and sustainable ecosystem objectives. We discuss the development of wetland restoration and management strategies for quality wetland complexes needed for waterbirds during their annual life cycles. Further, we underscore the importance of wetland management by our state, federal and private land partners to manage wetland complexes to provide high quality habitat for a wide array of wetland wildlife.

  9. Hydrological and nutrient budgets of freshwater and estuarine wetlands of Taylor Slough in southern Everglades, Florida (U.S.A.)

    Sutula, M; Day, J; Cable, J; Rudnick, D

    Biogeochemistry [Biogeochemistry]. Vol. 56, no. 3, pp. 287-310. Dec 2001.

    Hydrological restoration of the southern Everglades will result in increased freshwater flow to the freshwater and estuarine wetlands bordering Florida Bay. We evaluated the contribution of surface freshwater runoff versus atmospheric deposition and ground water on the water and nutrient budgets of these wetlands. These estimates were used to assess the importance of hydrologic inputs and losses relative to sediment burial, denitrification, and nitrogen fixation. We calculated seasonal inputs and outputs of water, total phosphorus (TP) and total nitrogen (TN) from surface water, precipitation, and evapotranspiration in the Taylor Slough/C-111 basin wetlands for 1.5 years. Atmospheric deposition was the dominant source of water and TP for these oligotrophic, phosphorus-limited wetlands. Surface water was the major TN source of during the wet season, but on an annual basis was equal to the atmospheric TN deposition. We calculated a net annual import of 31.4 mg m super(-2) yr super(-1) P and 694 mg m super(-2) yr super(-1) N into the wetland from hydrologic sources. Hydrologic import of P was within range of estimates of sediment P burial (33-70 mg m super(-2) yr super(-1) P), while sediment burial of N (1890-4027 mg m super(-2) yr super(-1) N) greatly exceeded estimated hydrologic N import. High nitrogen fixation rates or an underestimation of groundwater N flux may explain the discrepancy between estimates of hydrologic N import and sediment N burial rates.

  10. The importance of beaver to wetland habitats and waterfowl in Wyoming

    McKinstry, MC; Caffrey, P; Anderson, SH

    Journal of the American Water Resources Association [J. Am. Water Resour. Assoc.]. Vol. 37, no. 6, pp. 1571-1578. Dec 2001.

    Beaver (Castor canadensis) are habitat-modifying keystone species, and their activities broadly influence many other plants and animals. Beaver are especially important to waterfowl in the western U.S. where riparian and wetland habitats comprise less than 2 percent of the landscape yet provide habitat for greater than 80 percent of wildlife species. Wyoming is currently ranked sixth of the 50 states in the size of its breeding waterfowl population, and beaver ponds may play a significant role in providing habitat for these birds. The objectives of this research were to: (1) identify streams in Wyoming where beaver are currently present, extirpated, or used to manage riparian habitat; (2) identify areas where beaver could be relocated to create wetlands and improve riparian habitat; (3) compare wetland surface areas between areas that have beaver with those that did not; and (4) compare waterfowl numbers in areas with and without beaver. Using a survey of 125 land managers in Wyoming, we found that beaver have been removed from 23 percent (6,497 km) of the streams for which managers had direct knowledge (28,297 km). The same managers estimated that there are over 3,500 km of streams where beaver could improve habitat conditions. The riparian width in streams with beaver ponds averaged 33.9 m (95 percent CI = 25.1-42.7 m) in contrast to 10.5 m (CI = 8.6-12.4 m) in streams without beaver. During waterfowl surveys we counted 7.5 ducks/km (CI = 0.9-14.4 ducks/km) of stream in areas with beaver ponds and only 0.1 ducks/km (no CIs calculated) of stream in similar areas without beaver present. Beginning in 1994, we restored beaver to 14 streams throughout Wyoming in an effort to create wetlands and improve riparian habitat. Waterfowl have been quick to respond to these important habitats. We feel that beaver restoration and management can be used to improve habitat in drainages where conflicts with other land uses are minimal.

  11. Wetland creation for rare waterfowl conservation: A project designed according to the principles of ecological succession

    Shuwen, W; Pei, Q; Yang, L; Xi-Ping, L

    Ecological Engineering [Ecol. Eng.]. Vol. 18, no. 1, pp. 115-120. Oct 2001.

    The practices of wetland creation and restoration for mitigating wetland loss have been frequently carried out throughout the world; however, many of these projects do not work well. In this paper, the authors analyze wetland creation from the aspect of whole-ecosystem development, and explain the extreme difficulty of human design in wetland creation by the theories of ecological succession. More space should be given to self-design than human design in wetland creation, and the principles of ecological succession enable us to better use the great design ability of nature in just the way we wish. A wetland creation project for rare waterfowl conservation in China Yancheng Biosphere Reserve was chosen as a demonstration, designed totally according to the principles of ecological succession and allowed to self-design free of interference from human activities. A 240 ha reed wetland was created from the lalang grassland after 4 years of self-design. Success was proved by its plant composition and a good habitat value for many more birds than in the same area 4 years before.

  12. Wetland-Water Column Exchanges of Carbon, Nitrogen, and Phosphorus in a Southern Everglades Dwarf Mangrove

    Davis, SE III; Childers, DL; Day, JW Jr; Rudnick, DT; Sklar, FH

    Estuaries [Estuaries]. Vol. 24, no. 4, pp. 610-622. Aug 2001.

    We used enclosures to quantify wetland-water column nutrient exchanges in a dwarf red mangrove (Rhizophora mangle L.) system near Taylor River, an important hydraulic linkage between the southern Everglades and eastern Florida Bay, Florida, USA. Circular enclosures were constructed around small (2.5-4 m diam) mangrove islands (n = 3) and sampled quarterly from August 1996 to May 1998 to quantify net exchanges of carbon, nitrogen, and phosphorus. The dwarf mangrove wetland was a net nitrifying environment, with consistent uptake of ammonium (6.6-31.4 mu mol m super(-2) h super(-1)) and release of nitrite + nitrate (7.1-139.5 mu mol m super(-2) h super(-1)) to the water column. Significant flux of soluble reactive phosphorus was rarely detected in this nutrient-poor, P-limited environment. We did observe recurrent uptake of total phosphorus and nitrogen (2.1-8.3 and 98-502 mu mol m super(-2) h super(-1), respectively), as well as dissolved organic carbon (1.8-6.9 mu mol m super(-2) h super(-1)) from the water column. Total organic carbon flux shifted unexplainably from uptake, during Year 1, to export, during Year 2. The use of unvegetated (control) enclosures during the second year allowed us to distinguish the influence of mangrove vegetation from soil-water column processes on these fluxes. Nutrient fluxes in control chambers typically paralleled the direction (uptake or release) of mangrove enclosure fluxes, but not the magnitude. In several instances, nutrient fluxes were more than twofold greater in the absence of mangroves, suggesting an influence of the vegetation on wetland-water column processes. Our findings characterize wetland nutrient exchanges in a mangrove forest type that has received such little attention in the past, and serve as baseline data for a system undergoing hydrologic restoration.

  13. Biogeochemistry of mercury in wetlands

    Lacerda, LD; Fitzgerald, WF

    Wetlands Ecology and Management [Wetlands Ecol. Manage.]. Vol. 9, no. 4, pp. 291-293. Aug 2001.

    The environmental behavior and accumulation of Hg in aquatic organisms is subtly complex and driven by chemically and biologically mediated reactions involving exceedingly small quantities of Hg in the atmosphere and natural waters. The atmospheric and aquatic biogeochemical Hg cycle associated with wetlands and their environs will be affected not only by localized discharges (e.g., rivers; waste water treatment facilities), and tidal exchange, but from direct and indirect (via watershed leaching) airborne transport and deposition of Hg from regional and longer range sources. Increasing control of potential polluting activities and the development of 'clean' technologies have resulted in a substantial decrease in Hg emissions to the environment from point sources especially in developed countries. Unfortunately, there is no evidence suggesting that there has been a decline in total global pollution related Hg emissions. Indeed, it appears that emissions and discharges in developing regions (e.g., Asia, Africa, South America) are reducing the potential improvements gained through environmental legislation and other initiatives. Such global pollution is apparent in elevated levels of total gaseous mercury (TGM) in the Arctic (Schroeder et al., 1998) and in the equatorial Atlantic (Lamborg et al., 1999) as compared to mid-continent regions of the north-central United States (Lamborg et al., 1995; 2000). Further, effects of pollutants from longer range and diffuse sources can present a time-delayed and spatially-displaced response which depends on the ecological characteristics of the receiving ecosystems (Salomons and Stigliani, 1995).

  14. The design of ecological landscape models for Everglades restoration

    Sklar, FH*; Fitz, HC; Wu, Y; Van Zee, R; McVoy, C

    Ecological Economics [Ecol. Econ.]. Vol. 37, no. 3, pp. 379-401. Jun 2001.

    Restoration of the Everglades is a multi-objective, multi-scale, multi-agency program that requires numerous computer models to test alternatives, understand ecosystem processes, and evaluate restoration performance. Landscape models used for Everglades restoration include hydrologic models, transition probability models, gradient models, distributional mosaic models, and individual-based models. As tools for restoration feasibility and as the backbone of the policies that will drive Everglades restoration for the next 20 years, it is critical that a wide audience evaluate the strengths and weaknesses of six landscape models. Simulations of historic hydropatterns and current hydropatterns, based mostly upon sheet-flow equations and canal-flow equations, respectively, have been the realm of the Natural Systems Model (NSM) and the South Florida Water Management Model (SFWMM). Despite a lack of biology in these two models, a comparison of their spatial output became the basis for the Comprehensive Everglades Restoration Plan (CERP) approved by the US Congress in October, 2000. SAWCAT, a transitional probability model, was based upon an analysis of the patchiness of cattail (Typha) and sawgrass (Cladium) cells in association with levees, water depth, and phosphorus. This statistical approach was used to predict the amount of sawgrass that would be converted to less desirable cattail, if phosphorus runoff patterns to the Everglades remained constant. The Everglades Water Quality Model (EWQM), a mass-balance gradient approach used to track phosphorus according to a simple net phosphorus removal coefficient, was used to design Storm Water Treatment Areas (STA) and to evaluate where and when phosphorus `thresholds' would be exceeded under various hydrologic restoration plans. The Everglades landscape Model (ELM), a complex distributional mosaic model, used site-specific biogeochemical mechanisms and mass-balance to control energy and material flows, and to predict changes in carbon and phosphorus structure of the soil, water, and plant communities as a result of modified water deliveries to the Everglades. The Across Trophic Level Spatial Simulation (ATLSS), also a distributional mosaic modeling approach, used individual-based rules of behavior to predict animal movement and abundance in relation to hydrologic restoration plans. When these landscape models are combined, they effectively contribute to water management and policy for Everglades restoration. To insure their effectiveness, an applied science strategy provides the framework for their integration into the restoration process.

  15. Changes to the landscape pattern of coastal North Carolina wetlands under the Clean Water Act, 1984-1992

    Kelly, NM

    Landscape Ecology [Landscape Ecol.]. Vol. 16, no. 1, pp. 3-16. Jan 2001.

    Wetland management in the United States is organized through a permit process that requires a permit be filed with the U.S. Army Corps of Engineers prior to wetland alteration. A collection of these permits from 1984 through 1992 was analyzed in conjunction with classified Landsat Thematic Mapper data from 1984 and 1992 in order to quantify changes to wetland habitat in the study area in coastal North Carolina. The wetland management process in the U.S. focuses on a site-by-site review, possibly overlooking important changes to wetlands at the landscape-scale. These the two datasets were used to determine if wetland habitat loss was occurring at permit sites, but also to determine if landscape-scale wetland fragmentation and reorganization were occurring in the area surrounding each permit site under the wetland management process. The use of these two datasets attempted to span two scales: the site-specific scale often used in the management of wetlands, and the landscape-scale where effects of such management are evident. Important conclusions from the research include the following. First, while several sources imply that coastal wetlands are disproportionately protected as a result of the widespread recognition of their habitat value, estuarine wetlands were altered much more frequently in the study area than their inland counterparts. Second, despite federal level efforts that require compensatory mitigation when wetland habitat is lost, such mitigation was required in only three percent of permits, ensuring wetland loss. Third, correlation between estimates of wetland loss from the Permit Record and from the remotely sensed record was minimal, highlighting the problems inherent to wetland delineation and implying alterations to habitat not evidenced in the permit record. Finally, landscape-scale changes of loss, fragmentation and habitat reorganization have occurred in estuarine emergent wetland habitat in areas adjacent to several permit sites, implying unanticipated additional impacts to permitted actions. Wetland loss at the permit site occurred with additional fragmentation in 80 percent of the sites examined. The results highlight the lack of agreement between management and landscape-scale wetland structure, function and change, and imply the importance of examining the spatial context of permit sites in the permit review and evaluation procedure.

  16. Assessing ecosystem integrity of restored prairie wetlands from species production-diversity relationships

    Mayer, PM; Galatowitsch, SM

    Hydrobiologia [Hydrobiologia]. Vol. 443, no. 1-3, pp. 177-185. Jan 2001.

    We assessed ecosystem integrity in restored prairie wetlands in eastern South Dakota, U.S.A., by examining the relationship between and diatom diversity and production. We asked three questions: (1) Is production related to species diversity? (2) Can production-diversity relationships be used to distinguish between restored and reference wetlands with the purpose of assessing ecological integrity? (3) Are production-diversity relationships influenced by species composition? Eight undisturbed, unrestored wetlands were chosen as references to compare to eight wetlands restored after drainage. Diatoms were collected from artificial substrates that allowed communities to be transplanted from restored to reference wetlands and visa versa. Production was measured as total cell biovolume and diversity as species richness. Neither diversity nor production alone differed between restored and reference wetlands. However, production was negatively related to diversity at restored wetlands, whereas production at reference wetlands was not. Communities transplanted from reference to restored wetlands exhibited a production-diversity relationship like that observed among control samples in restored wetlands. Likewise, communities transplanted from restored to reference wetlands apparently lost any such relationship after they were relocated. Production was dependent on species composition. Furthermore, production of some species differed by restored and reference wetland type. The negative relationship observed between diversity and production was strongly influenced by Rhopalodia gibba and Epithemia species, suggesting that these species were superior competitors under the conditions found in some restored wetlands. We consider restored wetlands displaying the highest production:diversity ratio to be the most impaired sites, based on the extreme deviation from reference wetlands. We conclude that the relationships between diversity and production provided a rapid measure of restored wetland integrity with respect to baseline conditions observed in reference sites.

  17. Wetland Vegetation Monitoring in Cootes Paradise

    Smith, T; Lundholm, J; Simser, L

    Ecological Restoration [Ecol. Restor.]. Vol. 19, no. 3, pp. 145-154. 2001.

    The goals of the Cootes Paradise restoration include increasing the diversity and abundance of wetland vegetation. Consequently, vegetation monitoring has been critical in assessing the results of restoration initiatives to date. Due to the scale and complexity of the situation, we have used a number of different techniques to measure the plant communities of Cootes Paradise. The data we have collected in surveys during the past seven years show the restoration to be an overwhelmingly positive venture. In addition, experience gained in the process has allowed us to evaluate several methods for the long-term monitoring of emergent and submergent plant communities.

  18. Application of aerial photographs, GIS, and GPS during the restoration of a former barrier-beach wetland in Lake Erie

    Kowalski, KP; Wilcox, DA

    Coastal GeoTools '01. Proceedings of the 2nd Biennial Coastal GeoTools Conference. [np]. 2001.

    Most of the coastal wetlands and barrier beaches along the U.S. shoreline of western Lake Erie have been destroyed or severely degraded by human development and alteration of coastal processes. As a result, an innovative restoration plan was started in 1994 at the 300-ha former barrier-beach wetland known as Metzger Marsh. The Metzger Marsh project took a new approach to coastal wetland restoration by using a dike to mimic the protection offered by the former barrier beach as well as a water-control structure to maintain the hydrologic connection between the marsh and Lake Erie. Aerial photographs, GIS, and GPS were critical to the identification and analysis of the historical conditions in the marsh upon which this restoration project is based. Large-scale color-infrared photographs of the marsh were acquired annually between 1994 and 2000 and interpreted to delineate major vegetation associations and identify biological changes associated with the restoration. Historical black and white panchromatic aerial photographs were interpreted to develop an understanding of the relationship of wetland condition, water-level fluctuations, and status of the barrier beach between 1940 and 1993. Major vegetation associations delineated in 1994 and verified with ground truthing provided signatures that in many cases could be traced back through older photographs. Delineations of major vegetation associations, land features, and identification attribute data from 1940 through 2000 were digitized into PC ARC/INFO GIS, edited, and used to create vegetation maps. ArcView GIS software provided a simple mechanism for simultaneously viewing multiple data sets, conducting basic areal and distribution analysis, and producing detailed hard-copy maps. Trimble DGPS equipment was used to calculate precise geographic data to guide ground-truthing exercises, simplify the geo-referencing of GIS coverages, and locate sampling quadrants. When compared to water-level data, the geospatial data showed that the amount of wetland vegetation in Metzger Marsh was directly affected by the natural high and low water levels as well as the presence or absence of the protective barrier beach.

  19. Wetland creation for rare waterfowl conservation: A project designed according to the principles of ecological succession

    Shuwen, W; Pei, Q; Yang, L; Xi-Ping, L

    Ecological Engineering [Ecol. Eng.]. Vol. 18, no. 1, pp. 115-120. Oct 2001.

    The practices of wetland creation and restoration for mitigating wetland loss have been frequently carried out throughout the world; however, many of these projects do not work well. In this paper, the authors analyze wetland creation from the aspect of whole-ecosystem development, and explain the extreme difficulty of human design in wetland creation by the theories of ecological succession. More space should be given to self-design than human design in wetland creation, and the principles of ecological succession enable us to better use the great design ability of nature in just the way we wish. A wetland creation project for rare waterfowl conservation in China Yancheng Biosphere Reserve was chosen as a demonstration, designed totally according to the principles of ecological succession and allowed to self-design free of interference from human activities. A 240 ha reed wetland was created from the lalang grassland after 4 years of self-design. Success was proved by its plant composition and a good habitat value for many more birds than in the same area 4 years before.

  20. Wetlands Protection: Assessments Needed to Determine Effectiveness of In-Lieu-Fee Mitigation

    GAO, WASHINGTON, DC (USA). [vp]. 2001.

    Of the estimated 220 million acres of marshes, bogs, swamps, and other wetlands in the United States during the colonial times, more than half have disappeared and others have become degraded. This decrease is due, primarily, to agricultural activities and development. Developers whose projects may harm wetlands must, according to environmental regulations, first avoid and then minimize adverse impacts to wetlands to the extent practicable. If harmful impacts are unavoidable, the developer must compensate by restoring a former wetland, enhancing a degraded wetland, creating a new wetland, or preserving an existing wetland. Such mitigation efforts can occur under the following three types of arrangements: (1) mitigation banks, under which for-profit companies restore wetlands under Army Corps of Engineers agreements and then sell credits for these wetlands to developers; (2) in-lieu-fee arrangements under which developers pay public or non-profit organizations fees for establishing wetland areas, usually under formal Corps agreements; and (3) ad hoc arrangements, under which developers pay individuals or companies to perform the mitigation. This report, determines the extent to which (1) the in-lieu-fee option has been used to mitigate adverse impacts to wetlands, (2) the in-lieu-fee option has achieved its intended purpose of mitigating such impacts, and (3) in-lieu-fee organizations compete with mitigation banks for developers' mitigation business. This report also discusses the use of ad hoc arrangements as a mitigation option.

  21. Use of Restored Small Wetlands by Breeding Waterfowl in Prince Edward Island, Canada

    Stevens, CE*; Gabor, TS; Diamond, AW

    Restoration Ecology [Restor. Ecol.]. Vol. 11, no. 1, pp. 3-12. Mar 2003.

    Since 1990 under the Eastern Habitat Joint Venture over 100 small wetlands have been restored in Prince Edward Island, Canada. Wetlands were restored by means of dredging accumulated sediment from erosion to emulate pre-disturbance conditions (i.e., open water and extended hydroperiod). In 1998 and 1999 we compared waterfowl pair and brood use on 22 restored and 24 reference wetlands. More pairs and broods of Ring-necked Ducks, Gadwall, Green-winged Teal, and American Black Ducks used restored versus reference wetlands. In restored wetlands waterfowl pair density and species richness were positively correlated with wetland/cattail area, percent cattail cover, and close proximity to freshwater rivers. In addition, a waterfowl reproductive index was positively correlated with percent cattail cover. Green-winged Teal pair occurrence in restored wetlands was positively correlated with greater amounts of open water and water depths. American Black Duck pairs occurred on most (86%) restored wetlands. Restored small wetlands likely served as stopover points for American Black Duck broods during overland or stream movements, whereas they likely served as a final brood-rearing destination for Green-winged Teal broods. We suggest that wetland restoration is a good management tool for increasing populations of Green-winged Teal and American Black Ducks in Prince Edward Island.

  22. A Dying Delta? A Case Study Of A Wetland Paradigm

    Timoney, K

    Wetlands [Wetlands]. Vol. 22, no. 2, pp. 282-300. Jun 2002.

    The Peace-Athabasca Delta, Canada, a RAMSAR Wetland of International Significance, has since the 1970s been viewed as an ecosystem in decline. The putative reason for its decline has been the regulation of the Peace River by the W.A.C. Bennett Dam in British Columbia. The dying delta paradigm has its origin in a short-term study that coincided with a transient drawdown of the open drainage lakes in the delta. The paradigm has circumscribed all subsequent studies of the delta in its a priori assumption that all detected changes are due to the dam and are negative. As a result, the growth of scientific understanding has been stifled. Factors that contribute to the lack of ecological understanding include problems of data quality, quantity, and scale, ecological complexity, media marketing, failure to consult or analyze older/historical datasets, over-reliance on gray literature, too few wetland ecologists, and too little interdisciplinary thinking. Factors that may be involved in the recent changes, or lack of changes, include climatic variation and change, normal wetland dynamism, stochasticity, flow regulation, weirs, dredging, avulsions and their prevention, influxes of weeds and contaminants, delta evolution, and cultural change. The assessment of health in a delta is problematic since deltas are naturally stressed, dynamic ecosystems. Indicators of anthropogenic stress, such as declines in diversity and abundance, changes in biomass and primary production, or retrogressive succession may be difficult to apply in deltas. Long-term datasets are required that allow differentiation of normal from anthropogenic changes. Critique of the 'dying delta' view reveals little scientific support. The often-stated decline in flood frequency seems to have no statistical basis. The ecological health of the Peace-Athabasca Delta was assessed based on 26 attributes; 18 attributes indicated health, 3 indicated stress /disease, and 5 attributes were either neutral or required study. When compared to other major deltas in North America, the Peace-Athabasca Delta stands out as a paragon of ecosystem health. This study presents a cautionary lesson in the power of unchallenged paradigms in shaping scientific and popular opinion. A new paradigm views the delta as predominantly healthy, driven by large-scale natural processes, complex, and dynamically varying.

  23. Anuran call surveys on small wetlands in Prince Edward Island, Canada restored by dredging of sediments

    Stevens, CE; Diamond, AW; Gabor, TS

    Wetlands [Wetlands]. Vol. 22, no. 1, pp. 90-99. Mar 2002.

    In 1990, the North American Waterfowl Management Plan (NAWMP) implemented a small-wetland restoration program in Prince Edward Island (PEI), Canada. Wetlands were restored by means of dredging accumulated sediment and organic debris to create open water and emulate pre-disturbance conditions. Three call surveys were conducted in the spring and summer of 1998 and 1999 to estimate abundance and occurrence of spring peepers (Pseudacris crucifer), wood frogs (Rana sylvatica), northern leopard frogs (Rana pipiens), American toads (Bufo americanus), and green frogs (Rana clamitans) on restored and reference wetlands. Numbers of species calling and abundance indices of northern leopard frogs, green frogs, and spring peepers were significantly higher on restored versus reference wetlands. The number of species calling in restored wetlands was positively correlated with proximity to freshwater rivers; in reference wetlands, the number was positively associated with forested perimeters and area of open water. Occurrence of calling green frogs in restored wetlands was positively correlated with percent cattail and, in reference wetlands, with proximity to other wetlands. Our results suggest that small wetland restoration projects may be a good conservation tool for anurans. We recommend further research on reproductive success and on local population trends in restored wetlands to determine if restoration is beneficial for anurans on PEI.

  24. Comparison of avian communities on restored and natural wetlands in North and South Dakota

    Ratti, JT; Rocklage, AM; Giudice, JH; Garton, EO; Golner, DP

    Journal of Wildlife Management [J. Wildl. Manage.]. Vol. 65, no. 4, pp. 676-684. Oct 2001.

    We compared avian use of 39 restored and 39 natural wetlands in North and South Dakota during spring and summer of 1997 and 1998. Wetlands were widely distributed, but restored- and natural-wetland pairs were from the same geographic locale and had similar characteristics, including wetland size. We conducted paired comparisons between restored and natural wetlands for wetland-bird density, waterfowl-breeding pairs, and wetland-avian abundance, species richness, and diversity. We also compared abundance, species richness, and diversity of birds on upland areas adjacent to wetlands. Canada goose (avian scientific names in Appendix A), mallard, redhead, and ruddy duck had higher densities on restored wetlands. We failed to detect differences in overall avian abundance, species richness, or diversity between restored and natural wetlands. We conclude that restored wetlands in the Prairie Pothole Region supported similar avian communities with equal or higher abundances than those of natural wetlands.

  25. Biogeochemical and ecological considerations in designing wetland treatment systems in post-mining landscapes

    Kalin, M

    Waste Management [WASTE MANAGE]. Vol. 21, no. 2, pp. 191-196. Apr 2001.

    Although wetlands have gained acceptance as important components of ecosystems in post-mining landscapes in the past decade, their roles in contaminant retention/removal have not been well integrated into the designing of restoration programs. This paper describes the integration of sediment microbial activities and natural precipitation processes, along with approaches to defining the contaminant load from the mine wastes. The contaminant removal rates, which can be expected by a wetland sediment, are summarized and how they need to be reflected in the wetland size required, and the carbon supply which is needed. Contaminant loading from mining wastes can be balanced by wetland ecological processes, including wetland primary production and microbial mineralization in the sediment. This ecological engineering approach is demonstrated using case studies on hard-rock mining waste in Canada.

  26. Watersheds in Watershed Restoration: The Role of Public and Private Partnerships in Implementing Restoration Programs in the Chesapeake Bay Region

    Street, WH

    Transactions of the North American Wildlife and Natural Resources Conference [Trans. N. Am. Wildl. Nat. Resour. Conf.]. no. 66, pp. 588-597. 2001.

    The Chesapeake Bay (Bay) is legendary for its tremendous fish, shellfish and wildlife production. Once known as the premier wintering grounds for migratory waterfowl and the largest producer of fish and shellfish in the country, the Bay's health is now a mere shadow of its former glory. At the root of its decline is increased nutrient and sediment pollution entering the bay as a result of the development of the Bay's shoreline and surrounding watershed. The state-of-the-art water quality model of the US Environmental Protection Agency Chesapeake Bay Program calculates that the Bay is receiving over five times the amount of nitrogen that it would under predevelopment conditions and that 57 percent of the current nitrogen loads are derived from non-point sources (Blankenship 2001). Like most watersheds across the country, finding an effective means to reducing non-point source pollution has been very challenging. However, the Chesapeake region has recently increased its focus on restoring natural filtering mechanisms to the landscape, specifically wetlands and riparian buffers. While these efforts are primarily driven by water quality goals, they also have tremendous benefits for wildlife habitat.

  27. The development of vegetative zonation patterns in restored prairie pothole wetlands

    Seabloom, EW; van der Valk, AG

    Journal of Applied Ecology [J. Appl. Ecol.]. Vol. 40, no. 1, pp. 92-100. Feb 2003.

    1. The spatial structure of plant communities can have strong impacts on ecosystem functions and on associated animal communities. None the less, spatial structure is rarely used as a measure of restoration success. 2. The restoration of hundreds of wetlands in the prairie pothole region in the mid-western USA provided an excellent opportunity to determine whether the re-establishment of abiotic conditions is sufficient to restore structure, composition and spatial patterning of the vegetation. 3. We mapped the topography and vegetative distributions in 17 restored and nine natural wetlands. We used these data to compare the composition and spatial structure of the vegetation in both wetlands types. 4. The composition of the plant communities differed between restored and natural wetlands; the restored wetlands lacked the well-developed sedge-meadow community found in most natural wetlands. However, the spatial heterogeneity was similar, although the zonation patterns were less well-developed in the restored wetlands. 5. Although the overall structure was similar, species distributions differed among wetland types, such that species were found more than 10 cm higher in restored wetlands than in natural wetlands. 6. Synthesis and applications. This study illustrates that restored plant community composition and spatial structure may converge on their targets at different rates. Evaluations of restoration success should consider spatial structure of communities along with compositional and functional metrics.

  28. Biomass And Nutrient Dynamics In Restored Wetlands On The Outer Coastal Plain Of Maryland, USA

    Whigham, D; Pittek, M; Hofmockel, KH; Jordan, T; Pepin, AL

    Wetlands [Wetlands]. Vol. 22, no. 3, pp. 562-574. Sep 2002.

    A three-year study of aboveground biomass and nutrient dynamics in twelve restored depressional wetlands of different ages demonstrated significant annual variability among sites. Annual variations appeared to be primarily due to differences in hydrologic conditions over the three years of the study. Differences among wetlands were not related to time since restoration. When data for all sites were combined, annual differences in biomass and most measurements of nutrients (concentrations and standing stocks) did not, however, differ significantly. These results suggest that differences that are measured at individual wetland sites may be less important at the landscape level. Biomass decreased from the outer temporary to inner submersed zone, and there were few differences among wetlands when the temporary, seasonal, and submersed zones were compared. Nutrient concentrations in the plant biomass increased from the temporary zone to the submersed zone, resulting in few differences in nutrient standing crops across zones. Results from this study demonstrate that some measurements of restoration success (i.e., biomass production) should be used cautiously because they are likely to be highly variable among sites and across years and thus may be of limited use in post-restoration monitoring. Other ecosystem parameters (e.g., nutrient concentrations of biomass) are much more constant spatially and temporally, indicating that nutrient cycling processes in vegetation were established quickly following restoration. Nutrient characteristics of wetland vegetation thus may be a useful metric for evaluating restoration success or failure.

  29. N, P, and K budgets along nutrient availability and productivity gradients in wetlands

    Venterink, HO; Pieterse, NM; Belgers, JDM; Wassen, MJ; De Ruiter, PC

    Ecological Applications [Ecol. Appl.]. Vol. 12, no. 4, pp. 1010-1026. Aug 2002.

    Nutrient enrichment in Western Europe is an important cause of wetland deterioration and the concomitant loss of biodiversity. We quantified nitrogen, phosphorus, and potassium budgets along biomass gradients in wet meadows and fens (44 field sites) to evaluate the importance of various nutrient flows (atmospheric deposition, flooding, groundwater flow, leaching, soil turnover rates) for availability of the growth-limiting nutrient(s). From the nutrient budgets, we assessed N, P, and K availabilities for plants and compared them with N, P, and K in aboveground biomass. Also, potential long-term effects of annual hay harvesting on nutrient limitation were assessed. Comparing N, P, and K availabilities with N, P, and K amounts in the vegetation revealed that (1) the assessed availabilities could explain amounts and variation of nutrients in the vegetation along the biomass gradients, and (2) N was likely the major limiting nutrient along the gradients and P and K could (co)limit growth in some of the sites. Increasing N availabilities along the biomass gradients were caused by increasing N turnover rates in the soil. The contribution of atmospheric N deposition (43 kg N/ha/yr at all sites) to N availability varied from similar to 63-76% in low-productivity meadows and fens to 24-42% in highly productive meadows and fens. P and K availabilities along the biomass gradients were primarily influenced by soil processes, as indicated by soil extractable nutrient pools. Flooding could explain 20-30% of K in aboveground higher plants but was less important for P or N availabilities. Nutrient input and output by groundwater flow were more or less negligible for nutrient availability. At low-productivity sites, N output by hay harvesting just accounted for N input from atmospheric deposition, whereas there was net output of P and K. At highly productive sites, there was net output of all three nutrients. Compared to total N, P, and K pools in the top soil, net K output (1-20% of soil K pool) was at many sites much larger than that of P (generally 0.5-3%) or N (0-3%). Hay harvesting particularly seems to create K limitation. Our results indicate that conservation or restoration of low productivity wetlands in Western Europe requires (1) stable site conditions controlling low N, P, and K turnover rates in the soil, and (2) in case of N limitation, annual removal of biomass by harvesting hay, or another management measure to counterbalance the N input from atmospheric deposition.

  30. A GIS-Based Score System for Siting and Sizing of Created or Restored Wetlands: Two Case Studies

    Palmeri, L; Trepel, M

    Water Resources Management [Water Resour. Manage.]. Vol. 16, no. 4, pp. 307-328. Aug 2002.

    Water bodies are impacted by watershed loads in terms of nutrients and xenobiotics. This impact impairs the designated uses of the water body. Often preventive actions and end-of-pipe treatments do not reach the acceptable load to ensure the water quality standard in the water body. Wetlands are suitable tools for improving the self-purification capacity of a water system and can be used as a tool to reduce pollutant loads in a river network. This paper presents a methodology for the Siting and Sizing of created or restored wetlands at the watershed level, based on Geographical Information Systems (GIS) technique and estimations of wetland required area. The final outputs of the methodology are a Land Score System for Siting and a first rough estimation for the Sizing. The combination of these two elements is expected to be useful as a planning tool for watershed management and wetland planning. In order to assess the reliability of the procedure two very different case-studies are considered.

  31. Temperate freshwater wetlands: types, status, and threats

    Brinson, MM; Malvarez, AI

    Environmental Conservation [Environ. Conserv.]. Vol. 29, no. 2, pp. 115-133. Jun 2002.

    This review examines the status of temperate-zone freshwater wetlands and makes projections of how changes over the 2025 time horizon might affect their biodiversity. The six geographic regions addressed are temperate areas of North America, South America, northern Europe, northern Mediterranean, temperate Russia, Mongolia, north-east China, Korea and Japan, and southern Australia and New Zealand. Information from the recent technical literature, general accounts in books, and some first-hand experience provided the basis for describing major wetland types, their status and major threats. Loss of biodiversity is a consequence both of a reduction in area and deterioration in condition. The information base for either change is highly variable geographically. Many countries lack accurate inventories, and for those with inventories, classifications differ, thus making comparisons difficult. Factors responsible for losses and degradation include diversions and damming of river flows, disconnecting floodplain wetlands from flood flows, eutrophication, contamination, grazing, harvests of plants and animals, global warming, invasions of exotics, and the practices of filling, dyking and draining. In humid regions, drainage of depressions and flats has eliminated large areas of wetlands. In arid regions, irrigated agriculture directly competes with wetlands for water. Eutrophication is widespread, which, together with effects of invasive species, reduces biotic complexity. In northern Europe and the northern Mediterranean, losses have been ongoing for hundreds of years, while losses in North America accelerated during the 1950s through to the 1970s. In contrast, areas such as China appear to be on the cusp of expanding drainage projects and building impoundments that will eliminate and degrade freshwater wetlands. Generalizations and trends gleaned from this paper should be considered only as a starting point for developing world-scale data sets. One trend is that the more industrialized countries are likely to conserve their already impacted, remaining wetlands, while nations with less industrialization are now experiencing accelerated losses, and may continue to do so for the next several decades. Another observation is that countries with both protection and restoration programmes do not necessarily enjoy a net increase in area and improvement in condition. Consequently, both reductions in the rates of wetland loss and increases in the rates of restoration are needed in tandem to achieve overall improvements in wetland area and condition.

  32. Nekton in Gulf Coast wetlands: fine-scale distributions, landscape patterns, and restoration implications

    Minello, TJ; Rozas, LP

    Ecological Applications [Ecol. Appl.]. Vol. 12, no. 2, pp. 441-455. Apr 2002.

    Many decapod crustaceans and fishes are common inhabitants of flooded salt marshes in the northwestern Gulf of Mexico, but spatial distributions are uneven, and population sizes are difficult to estimate. We measured fine-scale (1-10 m) distributions of nekton on the vegetated marsh surface using enclosure samplers in Galveston Bay, Texas, and used these patterns to estimate population size. Natant decapod crustaceans were abundant in the marsh; densities of juvenile brown shrimp Farfantepenaeus aztecus, white shrimp Litopenaeus setiferus, and blue crabs Callinectes sapidus were highest 1 m from the water's edge and declined rapidly to 10 m from the edge. We developed regression models to describe these fine-scale density patterns and validated the models with independent data on density distributions from two other marsh systems. We used a Geographic Information System to transfer the density models to a natural marsh landscape; the highly fragmented Elmgrove Point marsh was composed of shallow nonvegetated bottom (37.4% of the area) and Spartina alterniflora vegetation (62.6%) with similar to 15% of the vegetated area within 1 m of the marsh-water interface. We estimated that this 437-ha salt marsh complex supported populations of 16.2 million brown shrimp, 15.5 million white shrimp, and 11.3 million blue crabs. We divided the marsh complex into 39 sectors and examined relationships between nekton populations and landscape-scale patterns of marsh fragmentation. The amount of edge and the population estimates in a sector increased consistently with the amount of water up to similar to 20-25%. Nekton population declines were not apparent until the late stages of marsh disintegration (>70% open water). We also used our fine-scale density models to simulate the effects of adding creeks to a 1-ha created salt marsh of solid vegetation. For shrimp, 1-2 creeks/ha (or a comparable amount of edge) were required to reach populations equivalent to shallow nonvegetated bottom, and up to 6 creeks/ha were required to reach populations similar to those estimated for the natural marsh complex. Simulated populations of blue crabs reached levels in the natural marsh complex with the addition of fewer creeks (2-3 creeks/ha).

  33. A Review of Wetland Policies and Related Guidelines of Leading Nations and Korea with Emphasis on Creation of Artificial Wetlands

    Lee, Yong Hee; Lee, Mijin

    Ocean and Polar Research [Ocean Polar Res.]. Vol. 24, no. 1, pp. 93-114. Mar 2002.

    Legal regimes of major countries actively involved in wetland programs including USA, Japan, Germany, Netherlands, and Denmark, show that these leading nations have developed their own legal regimes and policies for the conservation and restoration of wetlands since early 1990s. The main feature of their position is to preserve, create and restore wetlands, including tidal flats. However, this approach, so called "mitigation" policy, is thus far, not a fully established policy but an evolving one. For Korea, there are only a few laws and policies which hint at the importance of creating coastal wetlands as a conservation measure, however, most of those systems only exist as vague provisions which lack any tangible and compulsory implementing procedures and technical guidelines. It seems that it is necessary to strengthen the legal measures for conserving coastal wetlands in Korea including specifying economic assessment methods and funding sources for the creation, restoration and rehabilitation of tidal flats to firmly establish a national wetland mitigation policy.

  34. Submerged aquatic vegetation-based treatment wetlands for removing phosphorus from agricultural runoff: response to hydraulic and nutrient loading

    Dierberg, FE; DeBusk, TA; Jackson, SD; Chimney, MJ; Pietro, K

    Water Research [Water Res.]. Vol. 36, no. 6, pp. 1409-1422. Mar 2002.

    Submerged aquatic vegetation (SAV) communities exhibit phosphorus (P) removal mechanisms not found in wetlands dominated by emergent macrophytes. This includes direct assimilation of water column P by the plants and pH-mediated P coprecipitation with calcium carbonate (CaCO sub(3)). Recognizing that SAV might be employed to increase the performance of treatment wetlands, we investigated P removal in mesocosms (3.7 m super(2)) stocked with a mixture of taxa common to the region: Najas guadalupensis, Ceratophyllum demersum, Chara spp. and Potamogeton illinoensis. Three sets of triplicate mesocosms received agricultural runoff from June 1998 to February 2000 at nominal hydraulic retention times (HRTs) of 1.5, 3.5 or 7.0 days. Mean total P (TP) loading rates were 19.7, 8.3 and 4.5 g/m super(2)/yr. After eight months of operation, N. guadalupensis dominated the standing crop biomass and P storage, whereas C. demersum exhibited the highest tissue P content. Chara spp. was prominent only in the 7.0-day HRT treatments while P. illinoensis largely disappeared. Inflow soluble reactive phosphorus (SRP) (10-163 mu g/L) was reduced consistently to near the detection limit (2 mu g/L) in the 3.5- and 7.0-day HRT treatments, and to a mean of 9 mu g/L in the 1.5-day HRT treatment. The mean inflow TP concentration (107 mu g/L) was reduced to 52, 29 and 23 mu g/L in the 1.5-, 3.5-, and 7.0-day HRT treatments, respectively. Total P concentrations in new sediment (mean = 641, 408 and 459 mg/kg in the 1.5-, 3.5-, and 7.0-day HRT mesocosms, respectively) were much higher than in the muck soil used to stock the mesocosms (236 mg/kg). The calcium content of new sediment was twice that of the muck soil (16.5% vs. 7.6%), demonstrating that CaCO sub(3) production and, perhaps, coprecipitation of P occurred. We observed no nocturnal remobilization of SRP despite diel fluctuations in pH and dissolved oxygen. Mean outflow TP (21 mu g/L) from a 147 ha SAV wetland (4-day nominal HRT) was similar to mean outflow TP in the 3.5-day and 7.0-day HRT treatments. The mesocosms adequately mimicked P removal and other important characteristics of the larger system and can be used to address research questions regarding treatment performance of full-scale SAV wetlands. Available data suggest that the incorporation of SAV communities into the stormwater treatment areas may benefit Everglades restoration.

  35. A comparison of created and natural wetlands in Pennsylvania, USA

    Campbell, DA; Cole, CA*; Brooks, RP

    Wetlands Ecology and Management [Wetlands Ecol. Manage.]. Vol. 10, no. 1, pp. 41-49. Feb 2002.

    Recent research suggests that created wetlands do not look, or function, like the natural systems they are intended to replace. Proper planning, construction, and the introduction of appropriate biotic material should initiate natural processes which continue indefinitely in a successful wetland creation project, with minimal human input. To determine if differences existed between created and natural wetlands, we compared soil matrix chroma, organic matter content, rock fragment content, bulk density, particle size distribution, vegetation species richness, total plant cover, and average wetland indicator status in created (n = 12) and natural (n = 14) wetlands in Pennsylvania (USA). Created wetlands ranged in age from two to l8 years. Soils in created wetlands had less organic matter content, greater bulk densities, higher matrix chroma, and more rock fragments than reference wetlands. Soils in reference wetlands had clay loam textures with high silt content, while sandy clay loam textures predominated in the created sites. Vegetation species richness and total cover were both greater in natural reference wetlands. Vegetation in created wetlands included a greater proportion of upland species than found in the reference wetlands. There were significant differences in soils and vegetation characteristics between younger and older created wetlands, though we could not say older created sites were trending towards the reference wetland condition. Updated site selection practices, more careful consideration of monitoring period lengths, and, especially, a stronger effort to recreate wetland types native to the region should result in increased similarity between created and natural wetlands.

  36. Creating wetlands for waterfowl in Wyoming

    McKinstry, MC; Anderson, SH

    Ecological Engineering [Ecol. Eng.]. Vol. 18, no. 3, pp. 293-304. Jan 2002.

    Over 1500 wetlands have been created in northeast Wyoming as a result of bentonite mining. The potential for future creation is high and many groups are interested in modifying wetland creation during the construction/reclamation stage to improve habitat for waterfowl. We examined a sample of 92 bentonite wetlands for waterfowl use in 1991 and 1992. Our main objective was to relate waterfowl use with variables that could be modified during the construction phase. In general, waterfowl use wetlands that are > 1.0 ha in size, located within complexes of > 5 wetlands within a 1 km radius, and have abundant emergent and submersed vegetation. Wetlands created through bentonite mining tend to be small (< 0.5 ha), shallow, and unvegetated, but no current guidelines exist for improving their design. Building on the concept of wetland complexes, biologists and engineers could improve this region's wetland resources dramatically if aspects of waterfowl ecology and management were incorporated into the design of future sites.

  37. Vegetation development, nutrient removal and trace gas fluxes in constructed Typha wetlands

    Wild, U; Lenz, A; Kamp, T; Heinz, S; Pfadenhauer, J

    Natural Wetlands for Wastewater Treatment. pp. 101-126. Advances in Ecological Sciences [Adv. Ecol. Sci.]. Vol. 12.

    This paper presents a multifunctional concept for the restoration of an agricultural landscape. The combination of raw material production, water purification and peatland restoration is tested in a degraded fen area in southern Germany. As part of this process Typha angustifolia L. and T. latifolia L. have been cultivated in two constructed wetlands (basin 1 and 2). The raw material will be used for the fabrication of insulating materials. The Typha stands developed rapidly. In the second growing season shoot density increased and an average density of 70 shoots per m super(2) was reached for T. angustifolia L. and 45 shoots per m super(2) for T. latifolia L. Nutrient removal in the wetlands was high for NO sub(3)-N and PO sub(4)-P and low for organic N. In degraded peatlands organic N, opposed to wastewater, seems to be bound in a more persistent form. Weekly measurements of trace gas fluxes (nitrous oxide, methane) in the constructed wetlands and on a drained grassland (reference plot) were carried out. Cumulated nitrous oxide fluxes of the reference plot were significantly higher as compared to the wetlands. For methane the situation was the other way round. Global warming potential (GWP) of basin 1 was more favorable compared to the drained grassland, whereas basin 2 showed the highest GWP.

  38. Scaling considerations of mesocosm wetlands in simulating large created freshwater marshes

    Ahn, C; Mitsch, WJ

    Ecological Engineering [Ecol. Eng.]. Vol. 18, no. 3, pp. 327-342. Jan 2002.

    To explore the effects of experimental scale on ecological functions in wetlands, flow-through mesocosm wetlands (1 m super(2)) were compared over the first two growing seasons to a large, created, flow-through wetland (10 000 m super(2)) over four growing seasons. Hydrology was generally similar with mean hydraulic loading rates of 7.8 cm day super(-1) for the large wetland (excluding an extensive flooding year of 1995) and 6.3 cm day super(-1) for mesocosms. Mean hydraulic retention time was 2.1 days for the large wetland and 1.7 days for mesocosms. Temperature of surface water decreased slightly from inflow to outflow in mesocosms, while it increased in the large wetland. Conductivity of water in mesocosms showed no significant changes from inflow to outflow, while it decreased significantly in the large wetland. Phosphorus was retained effectively in the large wetland for 3 of 4 years and was retained in the mesocosms during the first of 2 years. Phosphorus was exported in the second year in the mesocosms, when dissolved oxygen (DO) and redox potential dropped significantly. Net aboveground primary productivity was similar between mesocosm wetlands ( similar to 353 g m super(-2) year super(-1)) and the large wetland ( similar to 380 g m super(-2) year super(-1)). Extensive shading with no open space may have led to cooler water temperatures and lower water column productivity in the densely vegetated mesocosms than in the large wetland in the second year. Less surface turbulence in the mesocosms due to less fetch affected DO too. These conditions may have stimulated development of reduced conditions in mesocosm soils more rapidly than in the large wetland, thereby causing the release of phosphorus. Scale of experiments and mesocosm artifacts must be considered before the results from mesocosm studies are generalized to large field-scale wetlands.

  39. Waterbird Use of Bayland Wetlands in the San Francisco Bay Estuary: Movements of Long-billed Dowitchers during the Winter

    Takekawa, JY; Warnock, N; Martinelli, GM; Miles, AK; Tsao, DC

    Waterbirds [Waterbirds]. Vol. 25, suppl. 2, pp. 93-105. 2002.

    The San Francisco Bay estuary is a migration and wintering area for more than 1.5 million waterbirds on the west coast of North America. Because the estuary is located in a metropolitan area, development and diking of baylands (the region between the edge of the bay and the historical high tide line) have greatly altered the wetland landscape. Recently, conservation interests have promoted restoration of diked baylands to tidal salt marshes for the benefit of endangered native species. However, effects of tidal marsh conversion on the existing community of waterbirds in the baylands are largely unknown, especially in muted tidal marshes with restricted inflows and in artificial salt evaporation ponds where high waterbird densities are found. The first radio-marking study of the Long-billed Dowitcher (Limnodromus scolopaceus) was conducted in November-December 2000 to examine their use of baylands. We captured 32 birds by rocket netting in a muted tidal marsh on the North Bay and radio-marked them with 1.2 g transmitters affixed with glue. Individuals were tracked for an average of 20.3 d ( plus or minus 8.5 SD) and obtained 217 high tide and 195 low tide locations. Movements between tides (x = 1.29 plus or minus 1.48 SD km) and home range sizes (x = 17.7 plus or minus 16.0 SD km super(2)) were highly variable. Long-billed Dowitchers preferred open habitats such as muted tidal marshes during the high tide, but the majority (78.5%) also remained in these wetlands during low tide rather than feeding at nearby mud flats. Their avoidance of mud flats contrasted sharply with Western Sandpipers (Calidris mauri) but was similar to Black-necked Stilts (Himantopus mexicanus). Seven Long-billed Dowitchers flew 110 km inland to Central Valley wetlands in mid-December, a regional movement documented earlier for Dunlin (Calidris alpina) wintering on the coast. However, unlike Dunlin, their movements were not in response to rainfall but may have been in response to a low pressure front or possibly predictable flooding of fields in the Central Valley. Although the estuary is a major wintering area supporting large numbers of waterbirds, some birds such as Long-billed Dowitchers move inland to freshwater wetlands in the Central Valley.

  40. Black Sea Wetlands Conservation Priorities

    Black Sea Program of Wetland International, Kiev (Ukraine). 28 pp. 2002.

    Priorities in the conservation of the Black Sea coastal wetlands, which were developed, discussed and adopted at the international workshops 'The Importance of the Black Sea Coastal Wetlands, Especially for Migratory Waterbirds' and 'Conservation, Restoration and Wise-Use of Wetlands resources along the Black Sea Coast', held in February and September, 2000 in Odessa are listed and described. It was discussed current status of Black Sea wetlands, importance of wetland areas, main threats to Black Sea wetlands, current status of wetland conservation: legislative framework and institutional framework, priorities for conservation, recommended actions, international coordination and cooperation, inventory, research and monitoring, legislation, strategy and planning, site protection, species conservation, wetland restoration, wetland management, education and public awareness. Specific national recommended actions for Black Sea coastal countries (Bulgaria, Georgia, Moldova, Romania, Russia, Turkey, and Ukraine) and 'Odessa 2000 Declaration on Black Sea Wetlands' are presented. It was concluded that activities for the Azov-Black Sea wetlands should be intensified in a coordinated approach and that international co-operation on wetland conservation should be enhanced in the Azov-Black Sea region. Key activities that will be required both to develop and implement the 'Black and Azov Seas Wetlands Initiative' (BlackSeaWet Initiative) comparable to the MedWet Initiative are listed.

  41. Directory of Azov-Black Sea Coastal Wetlands

    Black Sea Program of Wetland International, Kiev (Ukraine). 229 pp. 2002.

    The Directory is based on the national reports prepared for the Wetlands International project 'The Importance of the Black Sea Coastal Wetlands in Particular for Migratory Waterbirds' sponsored by the Netherlands Ministry of Agriculture, Nature Management and Fisheries. The project focused on collection of the baseline information on Black Sea coastal wetlands and expanding of co-operation between experts from the Black Sea coastal countries (Bulgaria, Georgia, Moldova, Romania, Russia, Turkey, and Ukraine). The aims of the inventory are: (1) to identify the wetlands and the priorities for their conservation; (2) to identify the functions of each wetland and its ecological, social and cultural values (and uses); (3) to monitor changes in the extent and quality of wetlands and trends of the changes; (4) to provide a tool for the protection and sustainable utilisation of wetlands and associated coastal habitats, both at policy and management levels; (5) to allow comparison of wetlands at national and international levels; (6) to provide information to assist in raising public awareness of the value of wetlands; (7) to assess the success of policies affecting wetlands, including management and restoration programmes. The term 'wetland' is used in the sense of the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (the Ramsar Convention): 'areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres'. Exclusively marine systems were excluded from the inventory. The Directory includes information on 94 wetlands with a total area of 24829.63 km super(2). About 38.5% of the total area of Black Sea wetlands are in Russia, 29.6% in Ukraine, 23.6% in Romania and the remaining 8.3 % in Bulgaria, Georgia, Moldova and Turkey. Thirty-two Black Sea coastal wetlands, totalling 19452.98 km super(2), are of international importance and are considered as Ramsar sites. These wetlands include habitats such as reed-dominated marshes, forest riverside flood plains, inland lakes and lagoons, limans, deltas, coastal lagoons and bays, silt and sand flats, as well as artificial wetlands such as fish ponds, rice paddies and salt ponds. The Directory consists of a series of national reports, which includes general country information (area, population, neighbouring countries, climate, biogeographical zonation, administrative division, etc.), general description of coastal wetlands (location, area, status, protected areas, check lists and occurrence of threatened taxa in key sites, etc.), information on legislative and institutional basis for wetland conservation and research, series of accounts of wetlands. All the Black Sea coastal wetlands of international importance (according to the Ramsar criteria) and of national importance are included. The site descriptions include basic information on location, area, altitude, wetland type, physical features (geology, geomorphology and soils; hydrology; water quality; climate), principal vegetation, conservation measures taken and proposed, land use and possible changes in land use, disturbances and threats, economic and social values, fauna, special floristic values, research facilities, public awareness and education, and criteria for inclusion. Where feasible, a series of codes are provided, indicating the types of wetland habitat present. Other hydrologically linked wetlands and nearby wetlands of lower conservation value are listed. References to the criterion or criteria (according to Ramsar Convention) that justify the inclusion of a site in the inventory are also given. General map for the Black Sea region, general map for each country and maps of sites was included. Glossary of the terms used is presented. Categories, criteria and sub-criteria of IUCN red list of threatened species are given in the annex.