Integrity Of Wetlands Research Articles

Assessment on ecological integrity of typical lakes, reservoirs and wetlands in Tianjin, China

The ecological health assessment of lakes, reservoirs and wetlands can provide decision-making basis for ecosystem restoration and management. We selected 20 typical lakes, reservoirs and wetlands sampling points in Tianjin, based on physical, chemical, and biological community indicators data (zooplankton, phytoplankton, benthos, fish, large aquatic plants, riparian plants) obtained during the survey from August to September 2018. We constructed an index of ecological integrity (IEI) including physical integrity, chemical integrity, and biological integrity to evaluate their ecological health. The reference points were selected based on three aspects using standardized methods: habitat environmental quality index (QHEI), water quality status, and disturbance of human activities. The analytic hierarchy process was used to calculate the weight of the three indicators. The evaluation results of the ecological integrity of typical lakes, reservoirs and wetlands in Tianjin were finally obtained. The results showed that: 1) Among all the samples, "healthy" points accounted for 5.0%, "good" points accounted for 20.0%, "general" points accounted for 35.0%, "worse" points accounted for 30.0%, and "poor" points accounted for 10.0%. Ecological health status of typical lakes, reservoirs and wetlands in Tianjin was at a general level, with a trend that the west was better than the east with significant spatial differences. 2) Reference points were selected based on the combination of habitat score, water quality conditions, and human activity disturbance. Water quality indicators could reduce subjectivity when selecting reference points and promote the application of ecological integrity evaluation. 3) The applicability verification results showed that IEI could better characterize the health status of each point, and the discrimination efficiency was obvious, which was suitable for evaluating the ecological health of lakes, reservoirs and wetlands.

Influence of Anthropic Impacts on the Functional Structure of Aquatic Invertebrates in Subtropical Wetlands

Changes in land cover are the main threats to integrity and biodiversity of wetlands. Here, we evaluated the effects of agriculture and urbanization on the functional traits (FT) of aquatic invertebrate. We evaluated 30 wetlands distributed among agricultural, urban and natural landscapes on the south of Brazil. We selected eight FT that encompassed aspects of life history, morphology and behavioral strategies to functionally characterize invertebrate fauna and 10 environmental variables of wetlands. We collected 3868 organisms distributed among 138 taxa (Crustacea, Mollusca, Hexapoda. The RLQ analysis (environmental, R; species-abundances, L; species-traits, Q) showed that there was a relationship between environmental conditions and the functional composition of the invertebrates. The FT that were more sensitive to environmental changes were scrapers feeding habit, reproduction mode, resistance form, adult aquatic stage, flat body shape, and dispersal mode. Our results suggest that land use acted as environmental filters, as they promote the selection and convergence of specific characteristics that give organisms more resilience and/or resistance to cope with the effects of anthropogenic disturbances. Also this results showed that (i) human disturbance can influence directly on the dynamic of the wetlands ecosystems functioning and (ii) the efficiency of the use FT in the environmental monitoring.

Effects of Groundwater Level Changes Associated with Coastline Changes in Coastal Wetlands

Coastline changes caused by anthropogenic and natural influences inevitably alter coastal wetland groundwater levels. In this study, we apply Visual MODFLOW (VMOD) to assess the influence of different zonal coastline types (e.g., accretion, erosion, and stable zones) on groundwater levels of a coastal wetland in the Yellow River Delta (YRD), China. We also discuss the conceptual framework of groundwater level variation in accretion, erosion, and stable zones. Results show that: (i) The groundwater flow field varied with coastline changes in this seaside region, while a similar variation pattern was also found in both the upper southwestern region and the riverside of the Yellow River where groundwater levels are high; (ii) groundwater levels increased with the expansion in land area caused by silting, while groundwater levels exhibited a slightly decreasing trend in the erosion zone; and (iii) coastal wetland groundwater levels exhibited a progressively and significantly decreasing trend in zones protected by a dam. We found that the mechanisms that drive groundwater levels clearly responded to coastline alteration, and such findings could help in our understanding of how coastlines influence groundwater in freshwater wetlands and aid in maintaining the integrity of coastal wetlands.

Perspective: Developing Flow Policies to Balance the Water Needs of Humans and Wetlands Requires a Landscape Scale Approach Inclusive of Future Scenarios and Multiple Timescales

Maintenance of the natural flow regime is essential for continued wetland integrity; however, the flow regime is greatly influenced by both natural and anthropogenic forces. Wetlands may be particularly susceptible to altered flow regimes as they are directly impacted by water flows at a variety of time scales. In Puerto Rico, contemporary water management is decreasing freshwater recharge to wetlands and contributes to the salinization of important coastal wetlands as sea levels rise. Further, downscaled climate models predict an increase in drought frequency, intensity, and duration by mid-century. Conflicts over water allocation seem imminent between human and ecological needs. Current minimum flow policies are insufficient given the complexities of ecosystem processes and the changes in precipitation patterns and sea level rise that are expected in the future. Improved flow policies need to be established that reflect the functional relationships between specific representative ecological resources and components of the natural flow regime across all relevant time scales. Similarly, flow policies need to be developed within a landscape scale to implicitly address the socio-ecological trade-offs as well as the complexities of water management. Multi-disciplinary collaborations will be essential for increasing our resiliency to anticipated future changes.

Users’ perceptions and understanding of two urban wetlands in Harare, Zimbabwe

ABSTRACTWetland management and conservation is a priority in southern Africa, and urban wetlands are particularly vulnerable to pollution, development and environmental degradation. This study focuses on the perceptions of urban residents towards two wetlands in Harare, Zimbabwe, as a means of better evaluating their sustainability and management challenges. Questionnaires, interviews and focus groups of wetland users and residents were used, focusing on their attitudes towards and understanding of wetlands, and how the wetlands are used and valued from different perspectives. Results showed that urban wetland use is driven by broader economic, social and political conditions, and has compromised wetland integrity. The majority of respondents are aware of the socioeconomic benefits of wetlands, and also the negative environmental effects associated with wetland use. However, despite this awareness, there is little institutional or governmental support for more effective wetland use by residents, and existing wetland legislation is not being effectively implemented, hindering their sustainable use.

Development and evaluation of NatureServe’s multi-metric ecological integrity assessment method for wetland ecosystems

Abstract Many ecological monitoring and assessment programs include rapid assessment methods that employ indicators or metrics to track the degree of divergence of ecosystem condition from reference conditions. Although these rapid assessment methods use a combination of metrics to rate overall ecological condition, they rarely include tests of either the merits of the component metrics being assessed or the method of aggregating the metrics into an overall rating. We used a conceptual model of ecological integrity for wetlands and field data to select and test 15 rapid assessment indicators (using specific metrics) across a spectrum of major ecological factors or MEFs (landscape, buffer, vegetation, hydrology, soil). We applied these metrics to 220 wetland sites across six states (Colorado, Indiana, Michigan, New Hampshire, New Jersey, and Washington), using two assessment area (AA) approaches: 106 sites used 0.5 ha point-based AAs; 114 sites used variable-sized polygon-based AAs. We statistically tested metric ratings and factor scores for their discriminatory power (DP) in relation to a stressor index using the Kruskal-Wallis test, and for redundancy using Spearman rank correlation and scattergrams. Of the 15 metrics, 12 had good or strong DP and were not redundant. Across all metrics, only two pairs (vegetation pair and buffer pair) were strongly correlated. The soil metric had the lowest DP, but it was among the least redundant of any metric. The DP of buffer metrics was lower for point-based approaches than for polygon-based approaches because the buffer for point-based AAs often included additional wetland area. Aggregating individual metrics into MEF scores (e.g., vegetation, hydrology, soil), primary factors scores (Landscape Context, on-site Condition) and overall ecological integrity ratings, either maintained or improved the interpretability of the ratings. Our analyses support the use of 12 rapid field-based metrics, spanning Landscape Context and on-site Condition, to assess the ecological integrity of wetlands. Although tested here for wetlands, the models and metrics are also being applied to upland terrestrial ecosystems. Our findings confirm the merits of our rapid assessment method in providing an intermediate level of assessment that is efficient and ecologically meaningful, within states and across watersheds and regions.

Urban rain-fed lakes: macro-invertebrate assemblages associated with Egeria najas as indicators of biological integrity in wetlands of Corrientes Province (Argentina)

In northeast Corrientes Province, there are more than 50,000 semi-rounded shallow rain-fed lakes. Several lakes have been disturbed mainly because urbanization causes eutrophication due to the illegal discharge of wastewater. We compared 22 metrics based on the structural attributes of macro-invertebrates associated with Egeria najas across seasons between five lakes with different human disturbance levels. Sixty-six samples of E. najas and associated invertebrates were collected seasonally using a net with an area of 962 cm2. A total of 17,737 macro-invertebrates of eight major groups, 35 families and 30 genera were recorded. The total macro-invertebrate abundance (number of individuals per plant dry weigh) and the family richness were significantly higher in less disturbed lakes than those under human disturbance, but the differences between seasons were not significant. Non-metric multidimensional scaling analysis differentiated the macro-invertebrate abundances between the more and less disturbed lakes; instead, the diversity indices were not useful for measuring the changes in the studied lakes. Besides, total number of taxa, number of EOT (Ephemeroptera, Odonata, Trichoptera) taxa, abundance and proportion of Trichoptera and abundance of Chironomidae reflected significant differences between the more and less disturbed lakes. Our results suggest that seven invertebrate metrics respond to urbanization, and they could be used to assess biological integrity of the studied lakes in complement of chemical monitoring of water quality. Management efforts should focus on the maintenance of macrophyte stands that provide high invertebrate diversity, which serve as food for a wide variety of fish.

Behavioural responses of the whooper swansCygnus cygnusto human disturbance and their adaptability to the different habitats in the Rongcheng lagoon of China

AbstractWith urbanization influences and economic development, the area and integrity of coastal wetlands are suffering destruction in China, which would affect waterfowl wintering. The Rongcheng Lake is an important wintering ground for migratory birds in Central Asia, especially for whooper swansCygnus cygnus. In this study, we investigated the numbers and behaviours of the whooper swans in the different habitats of the Swan Lake from November in 2015 to April in 2016, collected 72 water samples in the estuaries, and carried out food addition experiments in order to analyse the behavioural responses and adaptability of the whooper swans to the changing environment. Our results showed that the dominant behaviour of the whooper swans was resting, followed by feeding and locomotion and the whooper swans mainly distributed in the beach, estuary, and lagoon. Moreover, their distributions were affected by fresh water and food availability, whereas the human disturbance played an important role in their distributions and behavioural variations. To adapt to the changing environment, different wintering strategies were adopted by the whooper swans during the different overwintering period. The estuary protection and human feeding were very vital tools to help the whooper swans adjust their body to prepare for migrating next year.

Using vegetation attributes to rapidly assess degradation of East African wetlands

Wetlands in East Africa harbor a large biodiversity and provide diverse ecosystem services. Also, wetlands are highly suitable for crop production due to generally fertile soils and water availability. As a result of rising demand for cropland that is driven by population growth, degradation of upland areas and changing food demand patterns, wetlands are increasingly used for agricultural production. Such land use changes can negatively affect biodiversity and the provision of ecosystem services, especially when formerly little-disturbed wetlands are converted into croplands. For evaluating wetlands and developing land use or conservation strategies, we require methods to assess disturbance and degradation of wetlands. For instance, many indices of biological integrity for wetlands using vegetation attributes have been developed especially in the USA, but to date, no comparable assessment schemes are available for East Africa. To develop such a scheme, we sampled four different wetland localities, covering both floodplain and inland valley wetlands in Kenya, Rwanda, Tanzania and Uganda. A total of 198 wetland plots were characterized regarding land use and evaluated in terms of geomorphology, hydrology, vegetation and water quality regarding their deviation from a theoretical natural reference state without human disturbances and given respective impact scores using the WET-Health approach. Additionally, nine variables characterizing vegetation attributes were recorded. The impact scores were rescaled from 0 to 1 and used as response variables in multiple linear regression models. The predictor variables were selected for each regression model out of the nine vegetation attributes in a stepwise process. The regression models for the different response variables differed strongly regarding their accuracy. The root mean square prediction error (RMSPE) ranged between 0.14 for the “vegetation disturbance” and 0.27 for the “hydrological modification” regression model. However, we conclude that vegetation attributes such as “absolute cover of perennial species” or “average height of vegetation” are generally useful to estimate anthropogenic impacts on East African wetlands as assessed with the WET-Health approach. The presented approach can hence be a pragmatic addition to the WET-Health approach as a cost-efficient and rapidly applicable method. Furthermore, it may also be useful for ex-post application to historic data and vegetation surveys.

Loon Nest Viability Model: A Performance Indicator for Improving Water-Level Regulation of Large Water Bodies

Rule curves dictating target water levels for management have been implemented in several water bodies in North America over the last 70 years or more. Anthropogenic alterations of water levels are known to affect several components of wetland ecosystems. Evaluating the influence of rule curves on biological components with simple performance indicators could help harmonize water level management with wetland integrity. We assessed the potential of using the probability of common loon nest viability as a performance indicator of long-term impacts of rule curves on nesting wetland birds. We analyzed the outcome of rule curves on the probability of loon nest viability in Rainy Lake and Namakan Reservoir, 2 regulated water bodies located along the Ontario-Minnesota border. The analysis was focused on 4 hydrological time series between 1950 and 2013: 2 sets of time series simulating rule curves used to manage the water bodies in the past decades (referred to as the 1970RC and 2000RC), one of the historical measured water levels, and one of computed natural water levels. The probability of loon nest viability under the 1970RC was 2× higher than under natural conditions in both water bodies. The probability was also 2× higher under the 2000RC than under the 1970RC in the Namakan Reservoir but not in Rainy Lake. The rule curves generally improved conditions for nesting loons in both water bodies. The presented performance indicator can be used to evaluate future rule curves before they are implemented in the Rainy-Namakan or other similar systems.

Regulation of drainage canals on the groundwater level in a typical coastal wetlands

Activities related to reclamation alter wetland hydrological regimes and inevitably cause changes to groundwater level, which can result in the ecological degradation of coastal wetlands. Decreasing the groundwater level by the construction of drainage canals is an approach that has been widely used to control levels of root zone soil salinity as well as to protect freshwater wetlands or to expand agricultural land area in coastal wetlands. In this study, we assessed the influences of different drainage canal designs on the groundwater level using the Visual MODFLOW (VMOD) interface. We also provided an optimized drainage canal design suitable for the Yellow River Delta (YRD). Results showed that: (i) the groundwater level decreased in areas close to drainage canals, while only negligible effects were found on the groundwater level in areas with no drainage canals; (ii) the influence of drainage canals on the groundwater level decreased as distance increased; and (iii) a drainage canal network design of a depth of 5 m, with canal configuration of north-south direction and canal spacing of 1000 m was more effective in reducing the groundwater level in the study area. Our findings indicated that changes in groundwater level by the construction of drainage canals could help in our understanding of how groundwater influences freshwater wetlands and also aid in maintaining the integrity of coastal wetlands.

Assessing the Integration of Wetlands along Small European Waterways to Address Diffuse Nitrate Pollution

Nitrate concentrations in numerous European fresh watercourses have decreased due to end-of-pipe measures towards manure and fertilization management, but fail to meet the environmental objectives. The implementation of complementary measures to attenuate diffuse nitrate pollution in densely populated regions characterised by limited available area has been barely studied. To tackle this issue, this study evaluates the feasibility of integrating Constructed Wetlands (CWs) along waterways as a promising tool to facilitate compliance with the nitrate regulations. The aim is to calculate the required area of land alongside a specific watercourse to integrate CWs to reduce nitrate concentrations consistently below the 11.3 and 5.65 mgNO3-N/L levels, according to the Nitrates Directive and the Flemish Environmental Regulations. Nitrate-nitrogen removal efficiencies achieved at case study CWs were compared and validated with reported values to estimate the needed wetland areas. In addition, the removal efficiencies and areas needed to meet the standards were calculated via the kinetic model by Kadlec and Knight. The predicted areas by both methods indicated that CWs of 1.4–3.4 ha could be implemented in certain regions, such as Flanders (Belgium), with restricted available land. To conclude, three designs for ICWs (Integrated Constructed Wetlands) are proposed and evaluated, assessing the feasibility of their implementation.

Application of IBI and UAV Remote Sensing Technology to Assess Ecosystem Health of Poyang Lake Wetland

IBI is a widely used approach for assessing ecological integrity of wetland, it’s easy to be understood by the public. The ecosystem health of Poyang Lake Wetland was evaluated by IBI combined with UAV remote sensing technology. IBI was developed by means of vegetation data collected from Poyang Lake Wetland. 49 candidate vegetation metrics were tested for their ability to discriminate between sampling points with different interference levels. 8 metrics were eventually selected, and then they were transformed into uniform scores using ratio score method, the sum of the metric scores at a site becomes the IBI scores. Based on the 95% percentile of value in all sites, the criteria of health ranking is determined. The distribution range below 95% percentile is divided into 4 quarters. Result shows that among all sites, 6 were healthy, 12 were subhealthy, 8 were good-to-fair, 3 were fair and 1 was poor. The health status of Poyang Lake Wetland is closely related to the disturbance of human activities, and the health status of wetland in nature reserve is obviously superior to other areas.

Using structural equation modeling to link human activities to wetland ecological integrity

AbstractThe integrity of wetlands is of global concern. A common approach to evaluating ecological integrity involves bioassessment procedures that quantify the degree to which communities deviate from historical norms. While helpful, bioassessment provides little information about how altered conditions connect to community response. More detailed information is needed for conservation and restoration. We have illustrated an approach to addressing this challenge using structural equation modeling (SEM) and long‐term monitoring data from Rocky Mountain National Park (RMNP). Wetlands in RMNP are threatened by a complex history of anthropogenic disturbance including direct alteration of hydrologic regimes; elimination of elk, wolves, and grizzly bears; reintroduction of elk (absent their primary predators); and the extirpation of beaver. More recently, nonnative moose were introduced to the region and have expanded into the park. Bioassessment suggests that up to half of the park's wetlands are not in reference condition. We developed and evaluated a general hypothesis about how human alterations influence wetland integrity and then develop a specific model using RMNP wetlands. Bioassessment revealed three bioindicators that appear to be highly sensitive to human disturbance (HD): (1) conservatism, (2) degree of invasion, and (3) cover of native forbs. SEM analyses suggest several ways human activities have impacted wetland integrity and the landscape of RMNP. First, degradation is highest where the combined effects of all types of direct HD have been the greatest (i.e., there is a general, overall effect). Second, specific HDs appear to create a “mixed‐bag” of complex indirect effects, including reduced invasion and increased conservatism, but also reduced native forb cover. Some of these effects are associated with alterations to hydrologic regimes, while others are associated with altered shrub production. Third, landscape features created by historical beaver activity continue to influence wetland integrity years after beavers have abandoned sites via persistent landforms and reduced biomass of tall shrubs. Our model provides a system‐level perspective on wetland integrity and provides a context for future evaluations and investigations. It also suggests scientifically supported natural resource management strategies that can assist in the National Park Service mission of maintaining or, when indicated, restoring ecological integrity “unimpaired for future generations.”

Environmental Harshness Decreases ant β-Diversity Between Salt Marsh and Neighboring Upland Environments

Understanding how wetland organisms interact with neighbor habitats along environmental gradients is important to recognize wetland integrity and its connectivity at landscape-level. We evaluated whether assemblage characteristics (e.g. α-diversity) of marsh-ants are associated with geographic changes in environmental conditions, and if these factors are associated with marsh-upland dissimilarity in ant species composition (β-diversity). Ant-samples were collected both in the marsh and in the neighboring upland habitat at 5-sites along the South-west Atlantic (SWA) coastline (36°S to 40°S), encompassing two-distinct biogeographic regions. Generalized Linear Models showed that at the marsh scale, ant occurrence increased with maximum temperature and Spartina densiflora cover, but decreased with total-plant cover. Ant richness increased with salinity, S. densiflora cover and marsh area; and ant α-diversity increased with S. densiflora cover and decreased with total marsh plant cover and plant height. Composition of ant assemblages differed between the marsh and the upland habitat depending on the site, and β-diversity decreased with precipitation, salinity, tidal amplitude and α-diversity of the herbaceous stratum. Then, the abundance and α-diversity of ants varied along SWA marshes in relation to changes in local environmental factors and the regional landscape. Moreover, changes in species characteristics across coastal-landscape seem to interact with environmental gradients, resulting in reduced β-diversity values with increasing environmental harshness. Thus, our results suggest that the link of geographic changes in the physical environment with the changes in species traits drives the variation in marsh-upland dissimilarity across the space.

Imbalance of Ecosystem Services of Wetlands and the Perception of the Local Community towards their Restoration and Management in Jimma Highlands, Southwestern Ethiopia

Wetlands provide vital services for the livelihoods of local peoples; however, the ecological integrity of wetlands in Ethiopia has not yet been studied. In this study, we investigated the main ecosystem services of wetlands among different land use types, incorporating local perception toward wetland management. Six wetlands were selected from forested, agricultural and urban areas in the Jimma highlands. A total of 332 local residents within a 5-km radius of each wetland were surveyed. An additional 34 development agents and district and zonal experts were interviewed. The provisioning and cultural services were found to surpass the regulatory and supporting services of wetlands in agricultural and urban land uses compared with wetlands located in the forest. Although most individuals positively viewed wetland regulation and supporting services, the majority of households (66 %) were not interested in conserving wetlands because of small landholdings and the need to meet their livelihoods. Consequently, the vital regulatory and supporting services of impacted agricultural and urban wetlands are gradually becoming limited. Urgent action is, therefore, required to restore and protect these wetlands by promoting alternative livelihoods and improving the agricultural productivity of small landholders.

Implications of Institutional Vacuum in Wetland Conservation for Water Management

Wetlands are distinct ecological systems which provide numerous ecosystem services to human society and the environment. However, many of these important ecologically sensitive systems are threatened or are already lost, mainly due to anthropogenic pressures and land-use changes in their catchments. This article looks at the status of wetlands in India, discusses the existing legal and policy framework for wetland conservation, identifies the institutional vacuum leading to the loss of these freshwater ecosystems and assesses their implications for water management. The analysis indicates that it is difficult to estimate any sequential change in the overall wetland area by using estimates available from various wetland inventories since they all have used different methodologies and have considered different types of wetlands in their assessments. Further, deficient policy framework, poor implementation of existing policies and lack of interdisciplinary approach are the major institutional inadequacies in the approach to wetland conservation in India. As a result, various water management functions performed by wetlands, such as freshwater supplies, flood control, groundwater recharge and wastewater treatment, are under immense threat. Regulation of land-use changes in the catchment areas, pollution prevention and periodic assessment of water quality are suggested as major strategies to maintain the hydrological and ecological integrity of wetlands.

Environmental Quality and Aquatic Invertebrate Metrics Relationships at Patagonian Wetlands Subjected to Livestock Grazing Pressures.

Livestock grazing can compromise the biotic integrity and health of wetlands, especially in remotes areas like Patagonia, which provide habitat for several endemic terrestrial and aquatic species. Understanding the effects of these land use practices on invertebrate communities can help prevent the deterioration of wetlands and provide insights for restoration. In this contribution, we assessed the responses of 36 metrics based on the structural and functional attributes of invertebrates (130 taxa) at 30 Patagonian wetlands that were subject to different levels of livestock grazing intensity. These levels were categorized as low, medium and high based on eight features (livestock stock densities plus seven wetland measurements). Significant changes in environmental features were detected across the gradient of wetlands, mainly related to pH, conductivity, and nutrient values. Regardless of rainfall gradient, symptoms of eutrophication were remarkable at some highly disturbed sites. Seven invertebrate metrics consistently and accurately responded to livestock grazing on wetlands. All of them were negatively related to increased levels of grazing disturbance, with the number of insect families appearing as the most robust measure. A multivariate approach (RDA) revealed that invertebrate metrics were significantly affected by environmental variables related to water quality: in particular, pH, conductivity, dissolved oxygen, nutrient concentrations, and the richness and coverage of aquatic plants. Our results suggest that the seven aforementioned metrics could be used to assess ecological quality in the arid and semi-arid wetlands of Patagonia, helping to ensure the creation of protected areas and their associated ecological services.

Nutrient Dynamics in Wetlands of the Middle Paraná River Subjected to Rotational Cattle Management

The progressive degradation of wetlands has stressed the need of developing sustainable management strategies for maintaining their ecological character within the context of sustainable development. Rotational cattle grazing is a common grazing strategy in aquatic systems but its effect on nutrient dynamics in lakes is scarcely known. The objectives of this study were to evaluate if cattle produces a significant increase of TN and TP in wetlands, and if the value of these nutrients decrease after cattle are removed. Samples of water, sediment and macrophytes were collected for nutrient, organic matter and other chemical analyses. Results showed a significant increase in water nutrients during the presence of cattle, decreasing during their absence. These changes occurred surprisingly rapid, suggesting a high resilience of these systems to this impact. The presence of submerged vegetation in lakes ameliorated the effect of cattle on water nutrients, suggesting an important role of these plants in ecosystem management. Rotational management would minimize the increase of nutrients in water, maintaining the ecological integrity of wetlands.

Comparing disturbance gradients and bird-based indices of biotic integrity for ranking the ecological integrity of Great Lakes coastal wetlands

We compared different methods for generating indices of biotic integrity (IBIs) for Great Lakes coastal wetlands using bird community data collected by participants in Bird Studies Canada's Great Lakes Marsh Monitoring Program (GLMMP) including: rank sum and multivariate approaches for defining landscape disturbance gradients; and generalist-specialist (IBI-1), multimetric (IBI-2), and probabilistic (IBI-3) approaches for calculating IBIs. Scores from the multivariate disturbance gradient, IBI-1, and IBI-3 increased rapidly at the impaired and unimpaired ends of the impaired-to-unimpaired spectrum, whereas scores from the rank sum disturbance gradient and IBI-2 increased rapidly only at the unimpaired end. IBIs with metrics that both increased and decreased along the landscape disturbance gradient were more sensitive for identifying especially impaired and unimpaired sites (i.e., IBI-1 and IBI-3) compared to IBIs with metrics that only increased (i.e., IBI-2). Scores from all but one of the IBIs were significantly correlated with scores of at least one of the landscape disturbance gradients and scores from all three of the IBIs were significantly moderately correlated with each other (rs=0.3–0.7). Site ranks arranged from impaired to unimpaired differed by 25–50 positions out of 142 possible positions depending on the pair of IBIs chosen. Much of the variation that we observed could be explained by differences among IBIs in the metrics that contributed most to impaired and unimpaired sites. Thus, we recommend the following not only for IBI users assessing the integrity of Great Lakes coastal wetlands, but also any other ecosystem where multiple landscape disturbance gradients and IBIs are available for use: (1) use multivariate instead of rank sum approaches for defining landscape disturbance gradients; (2) use IBIs with metrics that both increase and decrease along the landscape disturbance gradient instead of IBIs with metrics that only increase or only decrease; and (3) ensure that site-level species lists are reasonably complete, particularly for species that disproportionately contribute to especially impaired and unimpaired scores. Following these guidelines will increase the sensitivity and accuracy of IBIs for identifying especially impaired and unimpaired sites and ultimately result in better conservation.