Coastal Wetland Change Research Articles

Palynological reconstruction of environmental changes in coastal wetlands of the Florida Everglades since the mid-Holocene

Palynological, loss-on-ignition, and X-ray fluorescence data from a 5.25m sediment core from a mangrove forest at the mouth of the Shark River Estuary in the southwestern Everglades National Park, Florida were used to reconstruct changes occurring in coastal wetlands since the mid-Holocene. This multi-proxy record contains the longest paleoecological history to date in the southwestern Everglades. The Shark River Estuary basin was formed ~5700calyr BP in response to increasing precipitation. Initial wetlands were frequently-burned short-hydroperiod prairies, which transitioned into long-hydroperiod prairies with sloughs in which peat deposits began to accumulate continuously about 5250calyr BP. Our data suggest that mangrove communities started to appear after ~3800calyr BP; declines in the abundance of charcoal suggested gradual replacement of fire-dominated wetlands by mangrove forest over the following 2650yr. By~1150calyr BP, a dense Rhizophora mangle dominated mangrove forest had formed at the mouth of the Shark River. The mangrove-dominated coastal ecosystem here was established at least 2000yr later than has been previously estimated.

Long term state of coastal lagoons in Veracruz, Mexico: Effects of land use changes in watersheds on seagrasses habitats

An increase in population over the last 50 years along the central coast of Veracruz on the Gulf of Mexico has led to a corresponding intensification of agriculture, urbanization, and other economic activities. Most significantly, this has resulted in rapid changes of land use and an increase in the area dedicated to agriculture and livestock. Native coastal wetland vegetation has declined significantly, and coastal lagoons systems are altered as they receive excess nutrients and sediments from agricultural and economic activities. The aim of this study was to evaluate the influence of productive activities on four coastal lagoons and one estuary at the watershed level and to establish reference points or ecological indicators upon which future changes in coastal wetlands may be measured. For this purpose we analyzed the physico-chemical characteristics of the water column, assessed the abundance and biomass of seagrasses, and determined the historical and current trophic status of these coastal water bodies. Our results indicate that over time the lagoons have remained in a eutrophic state, and only one has become mesotrophic. The biomass of the seagrass Halodule wrightii decreased by 28% from 1991 to 2001 in La Mancha Lagoon. Our results provide a baseline to assess future changes in the water quality of the selected study sites and the seagrasses populations they contain.

Detecting Shoreline Changes in Typical Coastal Wetlands of Bohai Rim in North China

Coastal wetland shoreline change represents one of the most important land-ocean interaction processes in complex and dynamic coastal environment. This paper presents the detecting of shoreline changes in four typical coastal wetlands of ecological importance along Bohai rim based on multi-temporal shorelines extracted from obtained Normalized Difference Water Index (NDWI) images using automatic binarization algorithm. Results showed that although there were statistical uncertainties dominant trends of the shoreline changes could be detected and sections that had significant area changes could be identified from satellite images. The reasons for corresponding changes occurred in these wetlands were stated in terms of natural processes and anthropogenic activities. It is our anticipation that this work would help future studies to reveal the regional/national pattern of wetland changes and support wetland protection and management in China's coast zone.

Analysis of ALOS PALSAR InSAR data for mapping water level changes in Yellow River Delta wetlands

Wetlands play a key role in regional and global environments and are critically linked to many major issues such as climate change, water quality, hydrological and carbon cycles, and wildlife habitat and biodiversity. It is very important to measure water level changes and consequently water storage capacity changes in wetlands to enable wetland protection and reconstruction. In this study, HH polarization L-band synthetic aperture radar (SAR) data were used in conjunction with synchronous field measurements and investigations to investigate the potential to detect water level changes under different types of wetlands. After evaluating factors that influence interferometric coherence, the framework for measuring water level changes using interferometric synthetic aperture radar (InSAR) phase information is presented in this article. Additionally, the SAR data obtained are used to investigate InSAR-derived water level changes in Yellow River Delta wetlands. The results show that InSAR technology has great potential for application in mapping water level changes in coastal wetlands, and InSAR-derived water level changes can supply unprecedented spatial details.

Soil organic carbon storage changes in coastal wetlands of the modern Yellow River Delta from 2000 to 2009

Abstract. Soil carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. The storages and dynamics of soil organic carbon (SOC) of 0–30 cm soil depth in different landscape types including beaches, reservoir and pond, reed wetland, forest wetland, bush wetland, farmland, building land, bare land (severe saline land) and salt field in the modern Yellow River Delta (YRD) were studied based on the data of the regional survey and laboratory analysis. The landscape types were classified by the interpretation of remote sensing images of 2000 and 2009, which were calibrated by field survey results. The results revealed an increase of 10.59 km2 in the modem YRD area from 2000 to 2009. The SOC density varied ranging from 0.73 kg m−2 to 4.25 kg m−2 at depth of 0–30 cm. There were approx. 3.559 × 106 t and 3.545 × 106 t SOC stored in the YRD in 2000 and 2009, respectively. The SOC storages changed greatly in beaches, bush wetland, farm land and salt field which were affected dominantly by anthropogenic activities. The area of the YRD increased greatly within 10 years, however, the small increase of SOC storage in the region was observed due to landscape changes, indicating that the modern YRD was a potential carbon sink and anthropogenic activity was a key factor for SOC change.

Remote Sensing of Wetlands: Case Studies Comparing Practical Techniques

To plan for wetland protection and sensible coastal development, scientists and managers need to monitor the changes in coastal wetlands as the sea level continues to rise and the coastal population keeps expanding. Advances in sensor design and data analysis techniques are making remote sensing systems practical and attractive for monitoring natural and man-induced wetland changes. The objective of this paper is to review and compare wetland remote sensing techniques that are cost-effective and practical and to illustrate their use through two case studies. The results of the case studies show that analysis of satellite and aircraft imagery, combined with on-the-ground observations, allows researchers to effectively determine long-term trends and short-term changes of wetland vegetation and hydrology.

Analyzing coastal wetland change in the Yancheng National Nature Reserve, China

Coastal zones provide habitat cores and corridors that maintain the diversity of entire landscapes, and they can form the cornerstone elements of regional conservation strategies. Natural environmental driving factors and excessive anthropogenic activities play important roles in coastal wetland change. Many studies have used remote sensing images to map and assess coastal wetland change on local or regional scales. This paper aims to provide insight into coastal wetland change in the Yancheng National Nature Reserve (YNNR) using remote sensing technology and landscape metrics analysis. The results reveal that grass flat and reed areas have significantly decreased, whereas agriculture fields, aquaculture ponds and built-up areas have continuously increased from 1988 to 2006. The spatial pattern of the coastal landscape has become fragmented and heterogeneous under great pressure from rapid economic development and population growth. The wetland changes have important impacts on natural habitat of the red-crowned cranes. The results of this study provide basic information that is required for developing measures toward a sustainable management and conservation of the YNNR.

Sea-level rise vulnerability in the countries of the Coral Triangle

Sea-level rise is a major threat facing the Coral Triangle countries in the twenty-first century. Assessments of vulnerability and adaptation that consider the interactions among natural and social systems are critical to identifying habitats and communities vulnerable to sea-level rise and for supporting the development of adaptation strategies. This paper presents such an assessment using the DIVA model and identifies vulnerable coastal regions and habitats in Coral Triangle countries at national and sub-national levels (administrative provinces). The following four main sea-level rise impacts are assessed in ecological, social and economic terms over the twenty-first century: (1) coastal wetland change, (2) increased coastal flooding, (3) increased coastal erosion, and (4) saltwater intrusion into estuaries and deltas. The results suggest that sea-level rise will significantly affect coastal regions and habitats in the Coral Triangle countries, but the impacts will differ across the region in terms of people flooded annually, coastal wetland change and loss, and damage and adaptation costs. Indonesia is projected to be most affected by coastal flooding, with nearly 5.9 million people expected to experience flooding annually in 2100 assuming no adaptation. However, if adaptation is considered, this number is significantly reduced. By the end of the century, coastal wetland loss is most significant for Indonesia in terms of total area lost, but the Solomon Islands are projected to experience the greatest relative loss of coastal wetlands. Damage costs associated with sea-level rise are highest in the Philippines (US $6.5 billion/year) and lowest in the Solomon Islands (US $70,000/year). Adaptation is estimated to reduce damage costs significantly, in particular for the Philippines, Indonesia, and Malaysia (between 68 and 99%). These results suggest that the impacts of sea-level rise are likely to be widespread in the region and adaptation measures must be broadly applied.

Analyzing qualitative and quantitative changes in coastal wetland associated to the effects of natural and anthropogenic factors in a part of Tianjin, China

Natural and anthropogenic factors in coastal wetland changes are widely discussed in wetland studies. Previous literatures have demonstrated that many factors may cause wetland change and argued that the global climate change and nutrient enrichment may become the most important ones in the next 50 years. Through field investigation, with the help of remote sensing technology and geographic information system, this research discusses the wetland change in Tianjin under the great pressure of rapid economic development, population growth, and sea-level rising. These findings include: (1) the wetland area expanded from 466.50 km 2 to 658.38 km 2 between 1987 and 1998, but it shrank to 550.5 km 2 by the year of 2006. (2) The results show that the groundwater has not been contaminated while the surface water has been polluted. (3) The questionnaire survey shows that the social environment in some specific ways impedes the protection of natural reserve. In order to achieve the harmony between human and nature, feasible countermeasures on how to keep ecological balance should be immediately taken. Consequently, natural conservation and sustainable economic development will be realized.

Habitat changes in coastal wetlands associated to hydrological changes in the watershed

In recent decades wetlands associated with the Mar Menor lagoon (SE Spain) have undergone several hydrological and biological changes as a consequence of increased water inputs from agricultural drainage off the watershed. Changes in the vegetal communities were studied by means of supervised classification of Landsat images, and TM and ETM+ sensors during the period 1984–2000, and a series of land cover maps was created. Changes in the wetland area during this period were analysed and a good fit was found with the total area of irrigated lands in the watershed. The series of land cover maps also allowed the study of the internal composition of the vegetal communities in each wetland. Important changes were detected, with an expansion of reedbeds and a significant reduction in the area occupied by priority habitats according to the Habitats Directive.

Analysis of Coastal Wetland Changes Using the “DPSIR” Model: A Case Study in Xiamen, China

Over the past several decades, human activities have had significant impacts on coastal wetlands worldwide. Here, using a model of “Drivers-Pressures-State-Impacts-Responses (DPSIR)” and data collected from coastal wetlands in Xiamen, China, we have analyzed temporal changes in regional coastal wetland ecosystem structure and function from 1950 through 2005. The study period was divided into four parts for comparative analysis: pre-1980s, 1980s, 1990s, and 2000 to present. Our results show that anthropogenic drivers of coastal wetland degradation in this region have increased substantially since 1950, and that this is correlated with a decline in coastal wetland function over the same period.

ISPRS Journal of Photogrammetry and Remote Sensing — Theme Issue “Remote Sensing and GIS for Coastal Ecosystem Assessment and Management”

Coastal ecosystem management involves procedures of monitoring and modeling which require reliable information base and robust analytical technologies. Remote sensing and GIS, given their costeffectiveness and technological soundness, are increasingly being used to develop useful sources of information and to support decision making in connection with a wide array of coastal applications. Recent innovations in data, technologies, and theories in the wider arena of remote sensing and GIS have permitted scientists with invaluable opportunities to advance the study of the coastal environments. This theme issue focuses on the use and applications of remote sensing and GIS techniques to develop environmental indicators for coastal ecosystem assessment and management. Specifically, this issue addresses the following topics (but not limited to): Nearshore bathymetry, shoreline erosion, and coastal morphologic change Characterization, analysis, and modeling of changing landscape structure and patterns in coastal environments Coastal wetland mapping and change detection Watershed hydrological and nutrient modeling in coastal environments Remote sensing of coastal water quality (chlorophyll concentration, turbidity, TSS and others) Mapping seagrass, littoral aquatic vegetation, and benthic habitats Linking conditions in upstream watersheds to downstream estuaries for integrated assessment of the estuarine ecosystems Coastal ecosystem management case studies

Freshwater Impacts in Normally Hypersaline Marshes

Heavy rainfall in 1978 and 1980 caused flooding of southern California salt marshes. Examination of three marshes demonstrated a broad range of freshwater effects which correlated with the degree of change in soil salinity. At Tijuana Estuary (1980), a short-term reduction in the salinity of normally hypersaline soils was followed by a 40% increase in the August biomass of Spartina foliosa. At Los Penasquitos Lagoon (1978), a longer period of brackish water influence was followed by a 160% increase in August biomass of Salicornia virginica. At the San Diego River (1980), flood flows were augmented by major reservoir discharge. Continuous freshwater flow leached most of the marsh soil salts and caused replacement of halophytes by freshwater marsh species. The first two cases probably fell within the normal range of flooding events, even though the hydrology of both watersheds has been modified. The vegetation response was functional; productivity increased but there was no major change in species composition. As expected, vegetation rapidly returned to preflood conditions. However, the long-term freshwater flow in the Dan Diego River was unnatural. Floral composition changed as soils were leached of salts. Recovery following the return of saline soils has been slow because many native halophytes are not good colonizers. The system's resilience is limited, and modification of natural stream discharge can cause permanent changes in coastal wetlands.