Degradation Of Coastal Wetlands Research Articles

A framework to quantitatively assess the influence of land use and land cover on coastal wetland hydrological connectivity from a landscape resistance perspective

Land use and land cover (LULC) change is one of the dominant factors contributing to coastal wetland degradation and loss. Most studies focused on LULC changes or whether they influenced on ecosystems. However, few studies quantitatively assessed the impact of different LULCs on hydrological connectivity. This study aimed to understand how LULC affected hydrological connectivity in the coastal wetlands in the Yellow River Delta (YRD), China, from 1985 to 2020. A framework from a landscape resistance perspective was used to evaluate the LULC's influence. LULCs were converted into a series of resistance surfaces whose values represent the degree to which LULC facilitated or restricted hydrological connectivity. The LULC's influence was evaluated by parameterizing the resistance surfaces using observed hydrological connectivity. The results showed that human-related LULC had more influence on hydrological connectivity. The critical time of LULC's influence on hydrological connectivity was 1985–1990 and 2010–2015. The critical areas were Zone II, Zone I, and Zone VI. The LULCs of agriculture, industry, town/city, and river had the most significant impact on the hydrological connectivity of the YRD coastal wetland. The result could direct LULC planning to mitigate the negative effect on coastal wetlands and provide support for the environmental impact assessment of coastal development practices. This paper advances the study by assessing LULCs' impact on hydrological connectivity and providing a quantitative method. The framework of this study enriches the coastal wetland conservation theory and policy-making of coastal management.

Coastal wetland degradation and ecological problems in the Yellow River Delta during 2005�2021

The Yellow River Delta wetland is one of the rare estuarine wetland ecosystems in the world, and it is also the most complete wetland ecosystem in the warm temperate zone in China. To understand its ecological problems as a sensitive and fragile new wetland ecosystem, we investigated and analyzed its coastal erosion, changes in wetland types, encroachment of invasive species, changes in the areas of seagrass beds and oyster reefs, ecosystem health status, and low salinity area. The investigation of the coastal wetlands in the Yellow River Delta revealed that from 2005 to 2020, the maximum deposition distance of the Yellow River port beach was about 10 km, and the maximum erosion distance was about 5 km. The siltation rate gradually decreased. From 2016 to 2021, the total area of the coastal wetlands in the Yellow River Delta remained stable. The area change rates of Spartina alterniflora, Phragmites australis, and Tamarix chinensis were 587, 282, and 57 ha/year, respectively, and the annual rate of change in Suaeda salsa was �60 ha/year. From 2015 to 2021, S. alterniflora increased the most sharply in the southern part of the Yellow River Estuary, and this region became the largest area of S. alterniflora in the delta. In recent years, the area of the coastal seagrass beds in the Delta has decreased sharply, and the area of the degraded oyster reefs has decreased further. The high nitrogen and phosphorus content of seawater is the main factor leading to the continuous eutrophication of the delta sea area. From 2011 to 2021, the health status of the Yellow River Estuary ecosystem remained in a sub-healthy state. The monitoring results for the low salinity area revealed that the areas of the low salinity area in 2020 and May 2021 were about 1200 and 1650 km2, respectively. Based on the survey results, the ecological problems faced by the wetlands in the Yellow River Delta such as dynamic coastline changes, coastal wetland degradation, and invasion of S. alterniflora were investigated.

Coastal wetland degradation and ecosystem service value change in the Yellow River Delta, China

The characteristics of changes in wetlands in different coastal areas vary, so it is necessary to select representative experimental areas to research wetland degradation, ecosystem service values (ESVs) and differences in changes among various wetland types in different ecological service function fields. The goal of this study is to better realize the spatiotemporal characteristics of wetland degradation and ESV in order to balance economic advancement and wetland ecological protection. The evolution of the wetland ESVs was analyzed by using the ESV equivalent correction technique and ecological contribution degree. The random forest (RF) classification model was utilized to extract wetland information in the Yellow River Delta (YRD) in four years (1990, 2000, 2010, and 2020). Thoroughly exploring the mechanism of impact and proposing reasonable suggestions based on a close combination of wetland changes and ecological services are conducive to the healthy development of global wetlands. The results demonstrated that the total area of wetlands expanded from 1459.5 km2 in 1990–1975.5 km2 in 2020, an increase of 28.5 %, with artificial wetlands increasing from 151.4 km2 to 1059.1 km2 and natural wetlands decreasing from 1308.1 km2 to 916.5 km2. The wetland ESV increased from 18.4 billion USD in 1990–28.6 billion USD in 2020. The transformation between types of natural wetlands tended to increase the ESV, while the transformation from natural wetlands to constructed wetlands reduced the ESV. The tidal flats and herbaceous wetlands have great value in terms of not only hydrological regulation but also gene diversity and climate regulation. The significant changes in various wetlands cause changes in different ecological service functions and promote changes in the ESV. Wetland protection, restoration, reconstruction, and rational utilization must be incorporated into urban land planning, and wetland parks and wetland protection zones should be established according to local conditions. This above research can provide typical examples and references for global wetland protection and sustainable development.

Coastal wetland restoration framework based on hydrogeomorphic units of the coastal wetland of Yancheng, China

Effective implementation of restoration projects is essential to solving the degradation of coastal wetlands. Due to the lack of systematic guidance or unsuitable engineering measures, some coastal wetland restoration projects have suffered from lower-than-expected results and poor sustainability. Therefore, it is necessary to construct a regional-scale wetland restoration framework from a macro perspective prior to project implementation, which can guide pre-study and follow-up restoration practices. In this study, the hydrogeomorphic units (HGUs) of Yancheng coastal wetlands were delineated according to the regional hydrogeomorphic conditions, and the changes in land use/cover and hydrological connectivity of each HGU from 1980 to 2019 were analyzed. The results showed that the area of natural wetlands in the study area declined rapidly, with a decline of 48.38%, and was mainly converted to aquaculture ponds or farmland during the 40 years. The structural complexity and transport capacity of tidal creeks decreased significantly, which indicated that the hydrological connectivity decreased. The main problems of degradation in the region were the reduction of large areas of natural wetlands, the rapid expansion of exotic species, and the decline in hydrological connectivity, etc. Combining the degradation problems and the restoration objectives, feasible strategies and methods were selected for different types of HGUs from both active and passive restoration categories, thus forming a coastal wetland restoration framework for the Yancheng coastal wetlands based on HGUs. This study takes regional hydrogeomorphology as the antecedent context condition, and the idea of a systematic restoration framework constructed by combining landscape perspectives can provide scientific support for wetland restoration practice.

Remote Sensing of Coastal Wetland Degradation Using the Landscape Directional Succession Model

In recent decades, human activities have impaired the structure, function, and diversity of coastal wetland ecosystems, and there is a need for the rational planning of ecological restoration to curb wetland degradation. However, the challenge remains to quickly and accurately identify degraded wetland areas and their degradation levels. In this study, we used remote sensing interpretation data from 1980 to 2020 and the wetland degradation evaluation method based on a landscape directional succession model to quantify the spatial and temporal characteristics of wetland degradation in Jiangsu Province, China. The key findings showed that 3020.67 km2 of wetlands became degraded over the 40 years of this study, accounting for 42.74% of the total area of coastal wetlands, and that the overall degradation was mild. This degradation presented significant spatial differences, with the wetland degradation in Yancheng City observed to be more serious than that in Nantong City. Degradation mainly occurred in Sheyang County, Dafeng District, Dongtai City, and Rudong County, and the spatial distribution pattern of severe and moderate degradation, mild degradation, and non-degradation was observed from land to sea in that order. The degradation of wetlands was observed to have obvious stages, and the degradation of coastal wetlands in the study area from 1980 to 2020 showed a significant increasing trend. The comprehensive score of wetland degradation in 2020 (1.67) was 3.70 times that in 1985 (0.45), and the turning point occurred in 2000. The types of wetland degradation were dominated by the transformation of natural wetlands into construction land (coastal industry), fish farming, and arable land, as well as the invasion of exotic species. Although great efforts have been made in recent years to protect and restore coastal wetlands, the development and utilization of coastal wetland resources should be strictly controlled to achieve the goal of sustainable development in coastal areas.

Detecting Vegetation to Open Water Transitions in a Subtropical Wetland Landscape from Historical Panchromatic Aerial Photography and Multispectral Satellite Imagery

Over the last century, direct human modification has been a major driver of coastal wetland degradation, resulting in widespread losses of wetland vegetation and a transition to open water. High-resolution satellite imagery is widely available for monitoring changes in present-day wetlands; however, understanding the rates of wetland vegetation loss over the last century depends on the use of historical panchromatic aerial photographs. In this study, we compared manual image thresholding and an automated machine learning (ML) method in detecting wetland vegetation and open water from historical panchromatic photographs in the Florida Everglades, a subtropical wetland landscape. We compared the same classes delineated in the historical photographs to 2012 multispectral satellite imagery and assessed the accuracy of detecting vegetation loss over a 72 year timescale (1940 to 2012) for a range of minimum mapping units (MMUs). Overall, classification accuracies were >95% across the historical photographs and satellite imagery, regardless of the classification method and MMUs. We detected a 2.3–2.7 ha increase in open water pixels across all change maps (overall accuracies > 95%). Our analysis demonstrated that ML classification methods can be used to delineate wetland vegetation from open water in low-quality, panchromatic aerial photographs and that a combination of images with different resolutions is compatible with change detection. The study also highlights how evaluating a range of MMUs can identify the effect of scale on detection accuracy and change class estimates as well as in determining the most relevant scale of analysis for the process of interest.

Effects of morphology and sediment permeability on coastal lagoons’ hydrological patterns

Mediterranean coastal lagoons are influenced from a wide variety of external factors such as surface and groundwater flows and climate dynamics. They are also vulnerable to human activities, which have caused a significant loss of these types of habitats. As a result, the EU habitat management have now prioritized restoration of natural wetlands. However, there is a lack of systemic studies on the mechanisms of coastal wetland degradation and ecohydrological processes that determine restored ecological functioning as an end goal, as well as a lack of reference sites to make comparisons. Furthermore, while lagoon morphometry and underlying sediment permeability have been studied extensively, combining these disciplines to evaluate lagoon hydrology and salinity dynamics is yet to be fully explored. The aim of this study was to analyze the hydrological dynamics of 4 newly constructed lagoons and compare them with 2 natural lagoons in the La Pletera salt marshes and evaluate the restoration and conservation efforts. We use the General Lake Model (GLM) to assess water volume fluctuations, salinity variability and lagoon water circulation (groundwater and surface water inflows, outflows and evaporation). We also combine data of the underlying lithological characteristics and lagoon morphometry, to compare and better understand the interplay of these parameters on the hydrological behavior of each lagoon. Results indicated that the older and natural lagoons exhibited more consistent patterns of confinement; with deeper morphologies, lower evaporation effect, lower water circulation, and more annual patterns of salinity fluctuation. The presence of low-permeability layers also resulted in less fluctuation of higher salinity levels. Conversely, three of the four new lagoons had similar, shallower morphologies and higher evaporation fluxes, but exhibited different water circulation patterns due to the presence or absence of low permeability layers. Also, their salinity fluctuations were more influenced by seasonal mixing than by evaporation, indicating more susceptibility to climatic influence in their annual hydrological pattern than in the natural lagoons. This could prove important when constructing and restoring lagoons according to predetermined morphology and underlying sediment patterns, as it could ultimately limit or enhance the success of set objectives and overall ecological functioning in a flooding – confinement driven lagoon ecosystem conditioned by irregular and unpredictable climatic events.

An evaluating system for wetland ecological risk: Case study in coastal mainland China

Coastal wetland degradation and fragmentation contribute to habitat and biodiversity loss. We construct wetland ecological risk assessment framework to evaluate the risk posed to 35 coastal wetland national nature reserves (NNRs) in China for the years 2000 and 2020. Our wetland ecological risk index (WRI) is based on an external hazard sub-index (EHI) and an internal vulnerability sub-index. Most NNRs have low EHI values in both 2000 and 2020. Ratios of change in EHI range from −22.76% to 52.15% (a negative value indicates a decrease, a positive value an increase), and the EHI for 20 of 35 NNRs (57.1%) decreases over time. Variation in the internal vulnerability index ranges −44.78% to 88.97%, and increases at 18 NNRs (51.4%) over time. WRI variation ranges between −48.13% and 82.91%, and increases at 19 NNRs (54.3%). Most NNRs are ranked as being at low, medium risk in both 2000 and 2020. Notably, the number of high-risk NNRs increases from 3 to 10 (for which WRI values also increase). Expansion of built-up land, cropland occupation (in 2020), road disturbance, and water quality are all significantly associated WRI. Intensified management of the 10 NNRs ranked at high risk is necessary to prevent further deterioration.

Detecting Coastal Wetland Degradation by Combining Remote Sensing and Hydrologic Modeling

Sea-level rise and climate change stresses pose increasing threats to coastal wetlands that are vital to wildlife habitats, carbon sequestration, water supply, and other ecosystem services with global significance. However, existing studies are limited in individual sites, and large-scale mapping of coastal wetland degradation patterns over a long period is rare. Our study developed a new framework to detect spatial and temporal patterns of coastal wetland degradation by analyzing fine-scale, long-term remotely sensed Normalized Difference Vegetation Index (NDVI) data. Then, this framework was tested to track the degradation of coastal wetlands at the Alligator River National Wildlife Refuge (ARNWR) in North Carolina, United States, during the period from 1995 to 2019. We identified six types of coastal wetland degradation in the study area. Most of the detected degradation was located within 2 km from the shoreline and occurred in the past five years. Further, we used a state-of-the-art coastal hydrologic model, PIHM-Wetland, to investigate key hydrologic processes/variables that control the coastal wetland degradation. The temporal and spatial distributions of simulated coastal flooding and saltwater intrusion confirmed the location and timing of wetland degradation detected by remote sensing. The combined method also quantified the possible critical thresholds of water tables for wetland degradation. The remote sensing–hydrologic model integrated scheme proposed in this study provides a new tool for detecting and understanding coastal wetland degradation mechanisms. Our study approach can also be extended to other coastal wetland regions to understand how climate change and sea-level rise impact wetland transformations.

Tracking the environmental impacts of ecological engineering on coastal wetlands with numerical modeling and remote sensing

Coastal wetlands are the most valuable ecosystems on the earth but facing severe degradation and losses owing to climate change and anthropogenic activities. Many ecological engineering projects (EEP) have been conducted to mitigate the degradation of coastal wetlands. However, the geomorphological impacts of EEP on coastal wetlands have not been well documented. In this study, a method employed a process-based hydrodynamic model and remote sensing (RS) was developed to evaluate the impacts of EEP on the geomorphological change of a prototype Ramsar site. Results demonstrated that RS can improve the quality of bathymetry data for the numerical model with a decrease of RMSE of bathymetry data from 0.52 m to 0.3 m. RS data also showed good capacity in trend detection of geomorphological change spatially. Results showed the Chongming Dongtan wetland experienced erosion with an annual rate of −0.035 m/yr from 2013 to 2016 after the implementation of EEP. The deposition rate changed significantly in the area within 200 m of the EEP. It is found that the EEP modified the composition of vegetation, sediment transportation, as well as substrate stability, affecting the geomorphological change of coastal wetlands. The study suggested that the EEP is a direct and effective way to restore the coastal habitats for waterbirds from moderate anthropogenic disturbance. However, the modification of the coastal wetland ecosystem by EEP will potentially increase the vulnerability to global climate change. Therefore, Future studies are needed to further evaluate the advantages and disadvantages of EEP and identify a more sustainable approach for coastal management.

One health pathogen surveillance demonstrated the dissemination of gut pathogens within the two coastal regions associated with intensive farming

BackgroundIntensive aquaculture farming has caused significant degradation of coastal wetlands and has been proposed as a reservoir for pathogenic Vibrio spp.ResultsGut pathogens including Vibrio spp., Salmonella spp., and Klebsiella spp. were isolated from bird feces, shrimp and wetland water in two typical coastal regions of China in 2015 and 2017 and were subsequently subjected to whole-genome sequencing. Meanwhile, local patient isolates were also selected to confirm the epidemiological links. Bacterial community composition analyses of the sediments that were sampled in 2015 and 2017 were conducted by the hypervariable region 4 of the 16S rRNA gene. Together with the local clinical isolates, we observed highly related Vibrio isolates from waterbirds, wetlands and shrimp. Phylogenetic genome comparisons also demonstrated that sequence types ST3 and ST2414 Vibrio parahaemolyticus isolates obtained from aquatic animals were clonally related to patient isolates. Likewise, three Salmonella typhimurium isolates were also genomically related to one clinical strain. The results showed that farming activities significantly altered the community composition and resulted in the emergence of several pathogens, including Acinetobacter, Mycobacterium and Legionella.ConclusionsIn conclusion, our results demonstrated that intensive shrimp farming in wetlands has two devastating impacts: pathogen dissemination from aquatic animals into migratory birds and transmission of foodborne pathogens into local communities.

Ensuring the adaptive potential of Coastal wetlands of India- the need of the hour for sustainable management

India is endowed with a variety of coastal wetlands viz., mangroves, seagrasses, saltmarshes, coral reefs, lagoons and tidal flats, and the country is also a signatory to the Ramsar Convention on Wetlands and the Convention of Biological Diversity, besides having a robust framework of laws and policies, governing the wetland conservation. However, the conservation strategies can better be improved in the context of increasing pressures and threats and limited success of restoration/rehabilitation. Land conversion and ecological degradation of coastal wetlands are the stressors, associated with rapid coastal developmental activities and climate change. The coastal wetlands require desired habitat niche and hence, the conversion of coastal wetlands to other land uses (including agricultural and urban lands) may lead to permanent loss, whereas ecologically degraded coastal wetlands may be resilient if supported by effective protection measures. Preventing the habitat conversion and maximizing the adaptive potential (viz., the ability of populations or species to adapt to rapid environmental change with minimal disruption) by preserving the ecological health are the need of the hour to safeguard the existing coastal wetlands and sustain the provisional ecosystem services offered by them rather than short-term increase in area by unproductive restoration/rehabilitation efforts. Since coastal wetlands are flow through ecosystems, preserving the hydrological connectivity, facilitating the connectivity between adjacent ecosystems and protection of natural corridors are potential strategies that are required to enhance the adaptive potential of coastal wetlands. This analysis calls for site-specific, long-term and integrated ecosystem-based protection, management and rehabilitation strategies based on scientific principles and enforcing the effective legislative measures to regularize the coastal developmental activities in India.

Great Lakes coastal wetlands as suitable habitat for invasive mute swans in Michigan

Great Lakes coastal wetlands provide critical habitat and food resources for more species than any other Great Lakes ecosystem. Due to past and current anthropogenic disturbances, coastal wetland area has been reduced by >50% while remaining habitat is frequently degraded. Invasive mute swans have contributed to the degradation of coastal wetlands by removing submergent vegetation and competitively excluding native species from breeding areas and food resources. Despite current control practices, mute swan population estimates in Michigan are ~8000, comparable to population estimates in the entire Atlantic Flyway of North America. We collected local abiotic data and adjacent land cover data at 3 scales from 51 sites during 2010 and 2011 and conducted 2 mute swan detection surveys each year during the summer and fall. We developed a single-species, single-season occupancy-based habitat suitability model to determine current and potential mute swan habitat among Great Lakes coastal wetlands. We found mute swans occupied heterotrophic coastal wetlands adjacent to urban areas, which were high in ammonium and oxidation-reduction potential and low in nitrates, dissolved oxygen, and turbidity. Our model provides managers with a valuable tool for rapidly identifying mute swan habitat areas for control efforts, particularly the need for targeting mute swan populations in or near urbanized areas. Our model will also aid managers in monitoring areas that mute swans may invade and prioritizing coastal wetland areas for restoration efforts.

Differences in the crab community structure between pristine and degraded Suaeda marshes after Spartina invasion

The degradation of coastal wetlands often threatens the diversity of native species. In addition to human activities, alien plant invasion is a major cause of local habitat degradation. Spartina alterniflora invasion results in extensive degradation of native Suaeda salsa marshes, and the difference in the macrobenthos between pristine and degraded S. salsa marshes remains unclear. Here, we compared the crab community structures of two S. salsa marsh sites on the Yellow Sea coast. One of the sites was coastal and experienced periodic tidal flooding, while the other site had migrated inland due to the encroachment of alien S. alterniflora onto the mudflat, which blocked the tide. A total of seven crab species were found in the two sites, and three and seven species were identified in the S. salsa marshes with and without tidal flooding, respectively. The S. salsa marsh that did not experience tidal flooding had the highest Shannon–Wiener index, while the S. salsa marsh that experienced tidal flooding had the highest total density. Our study highlighted that even if S. salsa marshes are preserved in nature reserves, there should be conspicuous differences in the crab communities between pristine and degraded S. salsa marshes after S. alterniflora invasion. Future conservation studies should assess the ecological value of different S. salsa marshes by paying increased attention to changes in the faunal groups of the habitats.

Quantitative assessment of the environmental risk due to climate change-driven coastline recession: A case study in Trincomalee coastal area, Sri Lanka

Climate change may exacerbate the environmental damage due to coastal hazards and increase associated risks. This would result in degradation of coastal wetlands, especially in developing countries due to the lack of sufficient resilience to coastal hazards such as inundation and coastal erosion. Environmental damages will lead to a decrease in services provided by the coastal wetland ecosystems that contribute to human wellbeing. To provide better insights on the little known issue of quantifying potential climate change-driven environmental risk, this article presents a stepwise approach to quantify coastline recession-driven risk associated with the tourism service provided by the Trincomalee beaches, dunes and pelagic system (Indian Ocean) along the East coast of Sri Lanka in 2110. To achieve this, here we first estimate the loss value of the tourism service due to sea level rise (SLR) and storm induced erosion in 2110, by using economic valuation techniques followed by a scenario-based approach. This is followed by the quantification of the environmental risk value by combining the result of the aforementioned loss value with the exceedance probability of coastal erosion derived from a prior study. Results show a medium environmental risk value ranging from 0 to 11,000 US$/Ha of beach area due to complete beach loss by 2110. This indicates that SLR and storm induced erosion in 2110 is not likely to pose a very high environmental risk associated with the tourism service of ecosystems in Trincomalee coasts. The approach presented in this study can be directly applied in other coastal areas of interest to gain a better understanding of the likely costs of climate change driven environmental risk, which is an emerging topic in coastal zone management.

Vulnerability of Al-hodidah wetlands in Yemen: main socio-economic causes

Abstract Wetlands provide a lot of benefits to local people such as cultivation, recreation, education, timber production, etc. Like any other country in the world, the aquatic biodiversity of wetlands in Yemen faces several threats as well as a regime of unsustainable human pressures. Several coastal wetlands were lost due to many problems. Understanding of the current situation could identify strategies to ensure the long-term conservation of wetlands. Therefore, this study aims to present the direct and indirect socio-economic causes of the coastal wetland degradation in Yemen. Ra's Eisa area (Al-hodidah coast in Red Sea) was chosen as the case study, while various people (decision makers, experts, practical coordinators and local people) were interviewed. The results show that livestock, agricultural production and wastes are the main socio-economic causes, in addition to tourism and Ra's Eisa Port activities near the wetland area. These causes are a result of the vegetative cover removal in the wetlands. The conclusion shows that the wetlands classification, awareness programs and emergency protection project should be implemented for all stakeholders especially local people. Finally, recommendations are suggested to guide decision-makers to achieve a sustainable vision for wetlands.

Decision support tool: Mottled duck habitat management and conservation in the Western Gulf Coast

The Western Gulf Coast provides important habitat for migratory and resident waterfowl. The mottled duck (Anas fulvigula) relies on this region for all of its life-cycle events. Its relatively small population, limited worldwide range, and generally declining population trajectory has earned it a “Red” status on the Audubon WatchList and is a species of concern among state and federal agencies. The Western Gulf Coast (WGC) mottled duck population decline is believed to be primarily caused by the historical conversion and degradation of coastal wetlands and native prairie, and recent declines in cultivated rice. There is general agreement among experts that negative impacts to nesting and brood-rearing habitat are the most important threats to the WGC mottled duck population and increasing recruitment is essential to the growth and sustainability of the population.Our goal was to use available knowledge of mottled duck nesting and brood-rearing requirements to develop a model to aid managers in targeting areas for conservation and management. We developed four spatially explicit models that: 1) identify and prioritize existing mottled duck nesting habitat for conservation (e.g., protection or maintenance); 2) identify and prioritize existing mottled duck brood-rearing habitat for conservation; 3) identify and prioritize areas for grassland establishment; and 4) identify and prioritize wetland basins for freshwater enhancement. Spatial models revealed that only 6 km2 and 9 km2 of nesting and brood-rearing habitat, respectively, were identified as highest priority (top 10%) for conservation in the WGC. Brood habitat was identified as potentially limiting recruitment in the Texas Mid Coast and the Laguna Madre subregions of our study area, whereas grassland habitat was potentially limiting recruitment in Chenier Plain and Mississippi River Coastal Wetlands subregions. Spatial models also revealed that there is a high density of areas of high priority for grassland establishment inland in Texas and Louisiana. Likewise, there is a high density of wetland basins of high priority for freshwater enhancement throughout coastal Louisiana and the upper Texas coast.We used two separate measures to assess the performance of our Mottled Duck Decision Support Tool (hereafter MODU-DST) and found that it adequately identified patch suitability, as defined by our model, with ≥79% accuracy. Using data from the Cooperative Breeding Mottled Duck Survey, we also found that breeding mottled ducks were using landscapes with optimal spatial arrangement of nesting and brood-rearing habitat, which is reflected by higher mean priority rankings of nesting and brood-rearing habitat in the landscape.

Analyzing Coastal Wetland Degradation and its Key Restoration Technologies in the Coastal Area of Jiangsu, China

Coastal wetland degradation severely affects ecological balance and economic and social sustainability. Ecological restoration of degraded wetlands is crucial in research on wetland degradation. A common problem with previous studies is that they use the same tactics and technologies over the whole study area, taking little account of the spatial heterogeneity of wetland degradation. This study focuses on the spatial heterogeneity of wetland degradation, and proposes the goals and technologies for wetland restoration by examining the main issues and causes of the degradation of coastal wetlands in Jiangsu, China. Habitat loss and absolute loss are the dominant forms of degradation in Jiangsu, followed by the existence of invasive species and gradual loss. Land reclamation and invasive species are the primary causes of the degradation of coastal wetlands. Appropriate technologies and engineering approaches are also proposed for the ecological restoration and reconstruction of degraded coastal wetlands against these degradation characteristics. They include the promotion of siltation in native wetlands, vegetation recovery, functional recovery of constructed wetlands, and prevention of invasive species.

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.

Integrative assessment and management implications on ecosystem services loss of coastal wetlands due to reclamation

The coastal wetland ecosystems are the critical ecological infrastructure and have a close relation to coastal sustainability. Rapid urbanization lead to a big demand of coastal reclamation in China thereafter caused the loss and degradation of coastal wetlands. In this study, we presented modified model suitable for quantifying ecosystem service values of different coastal system subtypes and assessing their loss due to coastal reclamations with a case of coastal agriculture-dominated city of Eastern China (Lianyungang). We focused on four major agriculture-related ecosystem services as follows: food production, raw material supply, disturbance regulation, and water purification. The results showed that: 32,346 ha of loss in coastal wetlands resulted in US$ 806 million year−1 loss in ecosystem service. The modified ecosystem service valuing models enable achieving categorized management of coastal ecological infrastructures. Furthermore, this study showed how to integrate the ecosystem service estimate into assessment, management, planning, restoration, and compensations of coastal ecological infrastructures.