Vulnerability Of Wetlands Research Articles

Success of coastal wetlands restoration is driven by sediment availability

Shorelines and their ecosystems are endangered by sea-level rise. Nature-based coastal protection is becoming a global strategy to enhance coastal resilience through the cost-effective creation, restoration and sustainable use of coastal wetlands. However, the resilience to sea-level rise of coastal wetlands created under Nature-based Solution has been assessed largely on a regional scale. Here we assess, using a meta-analysis, the difference in accretion, elevation, and sediment deposition rates between natural and restored coastal wetlands across the world. Our results show that restored coastal wetlands can trap more sediment and that the effectiveness of these restoration projects is primarily driven by sediment availability, not by wetland elevation, tidal range, local rates of sea-level rise, and significant wave height. Our results suggest that Nature-based Solutions can mitigate coastal wetland vulnerability to sea-level rise, but are effective only in coastal locations where abundant sediment supply is available.

Accretion, retreat and transgression of coastal wetlands experiencing sea-level rise

Abstract. The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to assess and quantify the expected impacts. Coastal wetlands respond to SLR by vertical accretion and landward migration. Wetlands accrete due to their capacity to trap sediments and to incorporate dead leaves, branches, stems and roots into the soil, and they migrate driven by the preferred inundation conditions in terms of salinity and oxygen availability. Accretion and migration strongly interact, and they both depend on water flow and sediment distribution within the wetland, so wetlands under the same external flow and sediment forcing but with different configurations will respond differently to SLR. Analyses of wetland response to SLR that do not incorporate realistic consideration of flow and sediment distribution, like the bathtub approach, are likely to result in poor estimates of wetland resilience. Here, we investigate how accretion and migration processes affect wetland response to SLR using a computational framework that includes all relevant hydrodynamic and sediment transport mechanisms that affect vegetation and landscape dynamics, and it is efficient enough computationally to allow the simulation of long time periods. Our framework incorporates two vegetation species, mangrove and saltmarsh, and accounts for the effects of natural and manmade features like inner channels, embankments and flow constrictions due to culverts. We apply our model to simplified domains that represent four different settings found in coastal wetlands, including a case of a tidal flat free from obstructions or drainage features and three other cases incorporating an inner channel, an embankment with a culvert, and a combination of inner channel, embankment and culvert. We use conditions typical of south-eastern Australia in terms of vegetation, tidal range and sediment load, but we also analyse situations with 3 times the sediment load to assess the potential of biophysical feedbacks to produce increased accretion rates. We find that all wetland settings are unable to cope with SLR and disappear by the end of the century, even for the case of increased sediment load. Wetlands with good drainage that improves tidal flushing are more resilient than wetlands with obstacles that result in tidal attenuation and can delay wetland submergence by 20 years. Results from a bathtub model reveal systematic overprediction of wetland resilience to SLR: by the end of the century, half of the wetland survives with a typical sediment load, while the entire wetland survives with increased sediment load.

Hydrologic flushing rates drive nitrogen cycling and plant invasion in a freshwater coastal wetland model.

Coastal wetlands intercept significant amounts of nitrogen (N) from watersheds, especially when surrounding land cover is dominated by agriculture and urban development. Through plant uptake, soil immobilization, and denitrification, wetlands can remove excess N from flow-through water sources and mitigate eutrophication of connected aquatic ecosystems. Excess N can also change plant community composition in wetlands, including communities threatened by invasive species. Understanding how variable hydrology and N loading impact wetland N removal and community composition can help attain desired management outcomes, including optimizing N removal and/or preventing invasion by nonnatives. By using a dynamic, process-based ecosystem simulation model, we are able to simulate various levels of hydrology and N loading that would otherwise be difficult to manipulate. We investigate in silico the effects of hydroperiod, hydrologic residence time, N loading, and the : ratio on both N removal and the invasion success of two nonnative species (Typha×glauca or Phragmites australis) in temperate freshwater coastal wetlands. We found that, when residence time increased, annual N removal increased up to 10-fold while longer hydroperiods also increased N removal, but only when residence time was >10d and N loading was >30gN·m-2 ·yr-1 . N removal efficiency also increased with increasing residence time and hydroperiod, but was less affected by N loading. However, longer hydrologic residence time increased vulnerability of wetlands to invasion by both invasive plants at low to medium N loading rates where native communities are typically more resistant to invasion. This suggests a potential trade-off between ecosystem services related to nitrogen removal and wetland invasibility. These results help elucidate complex interactions of community composition, N loading and hydrology on N removal, helping managers to prioritize N removal when N loading is high or controlling plant invasion in more vulnerable wetlands.

Functional Traits of Bats Associated with the Use of Wetlands in Colombian Tropical Dry Forests

Bats have a major functional role in wetlands; understanding how functional traits of bats depend on environmental characteristics can facilitate management of ecosystems and their services. In this study, we investigated how bat functional diversity has been affected by different anthropogenic impacts in wetlands of the Trans-Andean tropical dry forest of Colombia. Specifically, we analyzed how different functional traits responded to changing environmental conditions and land use and land cover patterns. We sampled six wetlands during the dry periods of the hydrological cycle from 2014 to 2018 and modeled the functional diversity as a function of environmental variables. To understand the association of bat community structure with environmental variables and biotic factors, we combined the RLQ analysis and the fourth-corner approach to relate environmental characteristics and species traits. The percentages of water surface area and pasture land were found to be associated with the general traits of bats when analyzed using the relative abundance of species. In addition, changes in functional diversity appeared to be driven mainly by larger species (e.g., Phyllostomus hastatus, Artibeus lituratus), whose presence was primarily associated with heterogeneous areas. The fourth-corner analysis revealed that the greatest length of skull is the trait that best describes the presence of bats in landscapes of pastures, water bodies, and high abundance of the shrubs Vismia sp. and Cecropia sp. These results suggest that combinations of specific features are important drivers of variation in functional diversity between wetlands. Considering the high vulnerability of Colombian wetlands, our findings provide fundamental information for the development of strategies for monitoring wetland biodiversity. The results can help identify priority conservation sites and improve environmental decision making.

Understanding enviro-climatological impact on fish biodiversity of the tropical floodplain wetlands for their sustainable management

Inland open water fisheries around the world are threatened due to growing anthropogenic pressures, climate change and overexploitation of the germplasm resources. Understanding how the floodplain wetland fish diversity responds to these unprecedented challenges is critical for developing alternative management and mitigation strategies in vulnerable wetland ecosystems. This communication elucidates the changing pattern of fish diversity in three moderately impacted tropical floodplain wetlands namely Bhomra, Mathura and Chandania in the lower Ganges basin during the year 2017–2019. Experimental fishing using gill net, drag net and cast net was carried out monthly to assess the fish diversity pattern in the three wetlands. Enviro-climatological parameters were assessed, and the important parameters influencing fish diversity were identified. Most of the critical environment parameters including pH, DO, water temperature were in the favourable range for fish. ANOVA indicated that pH, TDS, conductivity, salinity, transparency, depth and hardness showed significant difference (p < 0.05) among the three wetlands. Thirty-six fish species were recorded from the three wetlands out of which 2 species were vulnerable (VU) and 1 species was near threatened (NT). Species richness declined in all the studied wetlands ranging from 22.85 to 54% from the year 2002. The Canonical Correspondence Analysis showed a varying relationship of climatic and environmental parameters with the occurrence of fishes indicating species-specific adaptive capacity. The study also revealed a decrease in fish production (1991 to 2017) with the decreasing trend in rainfall and the increasing trend in temperature showing enviro-climatological influence. The new information generated would help to manage the wetland resources for sustainable fisheries enhancement and biodiversity conservation.

How Plants Influence Resilience of Salt Marsh and Mangrove Wetlands to Sea-Level Rise

This review evaluates the importance of plants and associated biological processes in determining the vulnerability of coastal wetlands to sea-level rise. Coastal wetlands occur across a broad sedimentary continuum from minerogenic to biogenic, providing an opportunity to examine the relative importance of biological processes in wetland resilience to sea-level rise. We explore how plants influence sediment accretion, elevation capital (vertical position in the tidal frame), and compaction or erosion of deposited material. We focus on salt marsh and mangrove wetlands, which occupy a similar physiographic niche and display similar physical and biological controls on resilience to sea-level rise. In both habitats, plants stabilize emergent mudflats and help sustain the wetland position in the tidal frame relative to ocean height through both surface and subsurface process controls on soil elevation. Plants influence soil elevations by modifying (1) mineral sediment deposition and retention, (2) organic matter contributions to soil volume, and (3) resistance to compaction and erosion. Recognition of the importance of plants in coastal wetland resilience to sea-level rise is key to accurate predictions about the future fate of salt marshes and mangrove forests and for development of effective management and restoration plans.

Spatio-Temporal Association of Fishing Cats with the Mammalian Assemblages in the East Godavari Mangrove Delta, India

Extrapolation of spatio-temporal association in the guild of vulnerable wetland species like the fishing cat (Prionailurus viverrinus Bennet, 1833) can inform strategies for conservation action. Camera trap study was conducted at Coringa Wildlife Sanctuary (CWLS) and the adjoined mangroves located in the East Godavari River Estuarine system (EGREE) which harbours the second largest population of fishing cats in India. The study recorded fishing cats (n = 495), jackals (n = 472), rhesus macaques (n = 186), smooth-coated otters (n = 24), jungle cats (n = 13), mongooses (n = 3), rodents (n = 49), birds (n = 62), and humans (n = 793). A predominant nocturnal activity was observed for the fishing cat and jungle cat, while the jackal showed bimodal activity. The fishing cat showed a high temporal overlap with rodents and considerable spatio-temporal segregation towards human disturbances. The overall structure of spatio-temporal relations indicates segregation in the guild and maybe an effective strategy to avoid competition. The anthropogenic stress and the negative interactions lead to conflicts which are detrimental in sustaining a viable fishing cat population in EGREE. Our study accentuates this fact and substantiates that EGREE delta region is a benign fishing cat habitat if human disturbances are abridged.

Nitrate distribution under the influence of seasonal hydrodynamic changes and human activities in Huixian karst wetland, South China

Karst wetland is a special, complex and fragile type of wetland. With increasing economic and agricultural activities, the negative impacts of human activities on water quality particularly on karst wetland is also increasing. In this paper multiple datasets and methods including hydrological, hydrochemical and stable isotope data were used to elucidate the distribution and transport of nitrate pollution in Huixian karst wetland under the influence of seasonal hydrodynamic changes and human activities. Hydrodynamic conditions around the wetland during both wet and dry seasons show large differences due to the complex exchange between surface water and groundwater. The northern recharge area receives rainfall recharge with rapid responses in groundwater level, temperature and electrical conductivity, while those responses are relatively stable in the central area where the surface water interacts with groundwater frequently. However, their diurnal variations are significant. In the western drainage area where groundwater always discharges to rivers, the groundwater levels show sharp responses after rainfall, but their temperatures are stable. In addition, δ15N and δ18O of nitrate suggest that the nitrate pollution mainly comes from NH4+ in fertilizer and rainfall, soil nitrogen, animal feces and livestock manure. The nitrate concentrations of most surface waters are lower during the wet season, affected by the dilution and mixing effect of heavy rainfall and agricultural activities. Nitrate distributions show considerable spatial variability during the dry season, especially in the wells located in residential areas which are mainly polluted by nearby residents. This study highlights the vulnerability of karst wetlands and presents methods that are significant for ecological restoration as well as development of karst water resources in karst areas.

Monitoring the Seasonal Hydrology of Alpine Wetlands in Response to Snow Cover Dynamics and Summer Climate: A Novel Approach with Sentinel-2

Climate change in the European Alps during recent years has led to decreased snow cover duration as well as increases in the frequency and intensity of summer heat waves. The risk of drought for alpine wetlands and temporary pools, which rely on water from snowmelt and provide habitat for specialist plant and amphibian biodiversity, is largely unknown and understudied in this context. Here, we test and validate a novel application of Sentinel-2 imagery aimed at quantifying seasonal variation in water surface area in the context of 95 small (median surface area &lt;100 m2) and shallow (median depth of 20 cm) alpine wetlands in the French Alps, using a linear spectral unmixing approach. For three study years (2016–2018), we used path-analysis to correlate mid-summer water surface area to annual metrics of snowpack (depth and duration) and spring and summer climate (temperature and precipitation). We further sought to evaluate potential biotic responses to drought for study years by monitoring the survival of common frog (Rana temporaria) tadpoles and wetland plant biomass production quantified using peak Normalized Difference Vegetation Index (NDVI). We found strong agreement between citizen science-based observations of water surface area and Sentinel-2 based estimates (R2 = 0.8–0.9). Mid-summer watershed snow cover duration and summer temperatures emerged as the most important factors regulating alpine wetland hydrology, while the effects of summer precipitation, and local and watershed snow melt-out timing were not significant. We found that a lack of summer snowfields in 2017 combined with a summer heat wave resulted in a significant decrease in mid-summer water surface area, and led to the drying up of certain wetlands as well as the observed mortality of tadpoles. We did not observe a negative effect of the 2017 summer on the biomass production of wetland vegetation, suggesting that wetlands that maintain soil moisture may act as favorable microhabitats for above treeline vegetation during dry years. Our work introduces a remote sensing-based protocol for monitoring the surface hydrology of alpine wetland habitats at the regional scale. Given that climate models predict continued reduction of snow cover in the Alps during the coming years, as well as particularly intense warming during the summer months, our conclusions underscore the vulnerability of alpine wetlands in the face of ongoing climate change.

A geospatially resolved wetland vulnerability index: Synthesis of physical drivers.

Assessing wetland vulnerability to chronic and episodic physical drivers is fundamental for establishing restoration priorities. We synthesized multiple data sets from E.B. Forsythe National Wildlife Refuge, New Jersey, to establish a wetland vulnerability metric that integrates a range of physical processes, anthropogenic impact and physical/biophysical features. The geospatial data are based on aerial imagery, remote sensing, regulatory information, and hydrodynamic modeling; and include elevation, tidal range, unvegetated to vegetated marsh ratio (UVVR), shoreline erosion, potential exposure to contaminants, residence time, marsh condition change, change in salinity, salinity exposure and sediment concentration. First, we delineated the wetland complex into individual marsh units based on surface contours, and then defined a wetland vulnerability index that combined contributions from all parameters. We applied principal component and cluster analyses to explore the interrelations between the data layers, and separate regions that exhibited common characteristics. Our analysis shows that the spatial variation of vulnerability in this domain cannot be explained satisfactorily by a smaller subset of the variables. The most influential factor on the vulnerability index was the combined effect of elevation, tide range, residence time, and UVVR. Tide range and residence time had the highest correlation, and similar bay-wide spatial variation. Some variables (e.g., shoreline erosion) had no significant correlation with the rest of the variables. The aggregated index based on the complete dataset allows us to assess the overall state of a given marsh unit and quickly locate the most vulnerable units in a larger marsh complex. The application of geospatially complete datasets and consideration of chronic and episodic physical drivers represents an advance over traditional point-based methods for wetland assessment.

Nitrogen Enrichment Accelerates Mangrove Range Expansion in the Temperate–Tropical Ecotone

Climate change and nutrient enrichment are two phenomena impacting coastal ecosystems. In coastal wetlands, mangroves in temperate–tropical ecotones are encroaching on adjacent saltmarshes, a pattern that is primarily attributed to warmer winter temperatures. Climate change is also expected to increase the vulnerability of coastal wetlands to eutrophication, and increases in nutrient availability may further mediate the rate of mangrove expansion. We investigated the consequences of nutrient enrichment on coastal wetlands in the mangrove–saltmarsh ecotone near the temperate edge of mangrove distribution along the northeast coast of Florida. We tested the hypothesis that nutrient enrichment enhances the ongoing, climate-driven expansion of mangroves into areas historically dominated by saltmarshes by increasing mangrove growth and cover, allowing them to outcompete and overgrow adjacent saltmarsh plants. We manipulated nitrogen (N) and phosphorus (P) availability and measured the effects on growth, cover, diversity, leaf traits, and nutrient dynamics of Avicennia germinans. We found that A. germinans shrubs growing in the saltmarsh–mangrove ecotone in northern Florida grew taller, increased their canopies, and had higher reproductive output when enriched with N compared to control plants and P-enriched plants. Nutrient enrichment did not alter Sarcocornia perennis growth and increased Batis maritima height but did not alter density or biomass. Nitrogen addition caused an increase in A. germinans cover and decrease in B. maritima cover and Simpson’s index of diversity, suggesting that N enrichment, an ongoing phenomenon, can hasten the invasion of mangroves into saltmarshes by favoring mangrove growth and reproduction without significantly enhancing saltmarsh plant growth.

Predicting the vulnerability of seasonally-flooded wetlands to climate change across the Mediterranean Basin

Predicting the vulnerability of seasonally-flooded wetlands to climate change across the Mediterranean Basin

Identifying Salt Marsh Shorelines from Remotely Sensed Elevation Data and Imagery

Salt marshes are valuable ecosystems that are vulnerable to lateral erosion, submergence, and internal disintegration due to sea level rise, storms, and sediment deficits. Because many salt marshes are losing area in response to these factors, it is important to monitor their lateral extent at high resolution over multiple timescales. In this study we describe two methods to calculate the location of the salt marsh shoreline. The marsh edge from elevation data (MEED) method uses remotely sensed elevation data to calculate an objective proxy for the shoreline of a salt marsh. This proxy is the abrupt change in elevation that usually characterizes the seaward edge of a salt marsh, designated the “marsh scarp.” It is detected as the maximum slope along a cross-shore transect between mean high water and mean tide level. The method was tested using lidar topobathymetric and photogrammetric elevation data from Massachusetts, USA. The other method to calculate the salt marsh shoreline is the marsh edge by image processing (MEIP) method which finds the unvegetated/vegetated line. This method applies image classification techniques to multispectral imagery and elevation datasets for edge detection. The method was tested using aerial imagery and coastal elevation data from the Plum Island Estuary in Massachusetts, USA. Both methods calculate a line that closely follows the edge of vegetation seen in imagery. The two methods were compared to each other using high resolution unmanned aircraft systems (UAS) data, and to a heads-up digitized shoreline. The root-mean-square deviation was 0.6 meters between the two methods, and less than 0.43 meters from the digitized shoreline. The MEIP method was also applied to a lower resolution dataset to investigate the effect of horizontal resolution on the results. Both methods provide an accurate, efficient, and objective way to track salt marsh shorelines with spatially intensive data over large spatial scales, which is necessary to evaluate geomorphic change and wetland vulnerability.

Predicting the vulnerability of seasonally-flooded wetlands to climate change across the Mediterranean Basin

Wetlands have been declining worldwide over the last century with climate change becoming an additional pressure, especially in regions already characterized by water deficit. This paper investigates how climate change will affect the values and functions of Mediterranean seasonally-flooded wetlands with emergent vegetation. We simulated the future evolution of water balance, wetland condition and water volumes necessary to maintain these ecosystems at mid- and late- 21st century, in 229 localities around the Mediterranean basin. We considered future projections of the relevant climatic variables under two Representative Concentration Pathway scenarios assuming a stabilization (RCP4.5) or increase (RCP 8.5) of greenhouse gases emissions. We found similar increases of water deficits at most localities around 2050 under both RCP scenarios. By 2100, however, water deficits under RCP 8.5 are expected to be more severe and will impact all localities. Simulations performed under current conditions show that 97% of localities could have wetland habitats in good state. By 2050, however, this proportion would decrease to 81% and 68% under the RCP 4.5 and RCP 8.5 scenarios, respectively, decreasing further to 52% and 27% by 2100. Our results suggest that wetlands can persist with up to a 400 mm decrease in annual precipitation. Such resilience to climate change is attributed to the semi-permanent character of wetlands (lower evaporation on dry ground) and their capacity to act as reservoir (higher precipitation expected in some countries during winter). Countries at highest risk of wetland degradation and loss are Algeria, Morocco, Portugal and Spain. Degradation of wetlands with emergent vegetation will negatively affect their biodiversity and the services they provide by eliminating animal refuges and primary resources for industry and tourism. A sound strategy to preserve these wetlands would consist of proactive management to reduce non-climate stressors.

Interannual lake fluctuations in the Argentine Puna: relationships with its associated peatlands and climate change

High elevation ecosystems are likely more sensitive to climate change. But, due to paucity of instrumental records, such effects are poorly studied, particularly in mountains outside Europe and North America. Here, we quantified water body area fluctuations for the last 32 years in 15 lakes spread over an area of 14.3 million ha in the Argentine Puna, through the classification of Landsat images; and we quantified peatlands NDVI (a proxy of vegetation productivity) from MODIS images. We evaluated the pairwise similarity between lakes interannual fluctuations and their relationship with climate models (TRMM 3B43 v7; CRU TS 4.10) and potential controls (ENSO index); and the correlations between water body area and the NDVI variation of its associated peatlands. Lakes were grouped in two clusters defined by their synchronic water body area variability and these clusters define two main geographic zones: NE and SW. Consistent with previous observations of an overall aridization trend, water body area generally decreased but showed large variability among lakes. Peatlands productivity was more correlated with lake variability than with modeled precipitation, and lake water body area was weakly related to indices of ENSO, providing an additional tool to relate local climate with continental and global climate models. The analysis shows that lake behavior is highly variable spatially and temporally, and that satellite-based monitoring is a valuable tool for assessing ecological conditions of wetlands in the region, characterized by the lack of climatic instrumental records; and to explore the vulnerability of wetlands to climate change.

Detecting inundation thresholds for dryland wetland vulnerability

Dryland wetlands receiving periodical floods are of key importance for ecological resilience. The inundation regime (i.e., frequency, duration, depth, and timing of inundation), is one of the major factors that determine the suitability of local conditions for specific wetland species. During droughts, inundation conditions can reach a threshold after which wetland vegetation could transition to dryland vegetation. This study analyses the response of vegetation to hydrologic variability in an arid wetland in Australia over a period of 22 years (including the Millennium drought) in order to identify inundation thresholds for transitions. We use numerical modelling, field observations and remote sensing data to relate continuous detailed simulations of the inundation regime with the response of patches of Common reed, Water couch and River red gum, three key vegetation associations in the study site. We focus in patches that were affected by the drought and presented dryland vegetation invasion as well as reference patches that remained healthy throughout the drought. On each patch, we compare annual and inter-annual simulated inundation regimes to the minimum inundation conditions that can support the specific vegetation, and we compute the percentage area of the patch that verifies minimum inundation for each year. We define this area percentage as minimum inundation index. This index is analysed in conjunction with Landsat derived information on green vegetation coverage (green Seasonal Fractional Cover) for the selected patches. We found that the minimum inundation index and inter annual frequency are able to describe the vegetation dynamics of the patches, which can be characterised by two distinct response modes that depend on a threshold value of the minimum inundation index. Inundation below the threshold noticeably leads to degraded vegetation, but the vegetation can recover quickly if this threshold is later maintained for one or two years. Values below the threshold for more extended periods (drought) result in a gradual decrease of wetland vegetation to almost complete disappearance after four years and subsequent dryland vegetation invasion.

Development of a multi-scale wetland Resilience Index from muskellunge nursery habitat in Georgian Bay, Lake Huron

In a 2012 study, no age-0 muskellunge (Esox masquinongy) were found in any of 16 historic nursery sites in coastal marshes of southeastern Georgian Bay (SEGB), and this was attributed to sustained low water levels (1999–2013) that had altered the vegetation structure of nursery habitat. In the same study, age-0 muskellunge were found in 16 coastal marshes surveyed in northern Georgian Bay (NGB), even though these sites had been subjected to the same water-level conditions. We hypothesize that hydrogeomorphic features of NGB sites made them resilient to effects of sustained low lake levels that made the SEGB sites unsuitable for age-0 muskellunge. Compared to their SEGB counterparts, the NGB nursery sites were significantly steeper, deeper, and less sheltered under low water levels. We used these hydrogeomorphic features to develop a multi-scale Resilience Index (RI) for identifying coastal wetlands that are resilient to stable low lake levels. The RI correctly classified the NGB and SEGB nursery sites, with an area-under-the-curve score of 0.973. Coarser-scale variants of the RI provide a regional screening tool in the identification of resilient wetland habitat (e.g. potential muskellunge nursery habitat), and a basin-wide approach to identify vulnerable wetland habitats. This multi-scale index, in conjunction with targeted field surveys, should provide managers a useful tool in the face of uncertain water level forecasts.

GALDIT-SUSI a modified method to account for surface water bodies in the assessment of aquifer vulnerability to seawater intrusion

The salinization of coastal aquifers is one of the major environmental issue worldwide. Overexploitation is the most common reason of salinization, since it generates a piezometric inversion, which in turn leads to groundwater flow from the coast towards inland. This also occurs in water bodies connected to the sea like lagoons, rivers, torrents and wetlands. In this study, a modification of the GALDIT method including “SUperficial Seawater Intrusion (SUSI)” is proposed. Six new parameters were added to the classical ones. The analytical hierarchy process and the sensitivity analysis were performed for weights definition and validation of the proposed GALDIT-SUSI method. Two study areas, with different characteristics were chosen for the application of both methods: the coastal area of Epanomi (Greece) and the Po River lowland (Italy). The application of the standard GALDIT in both sites showed a poor discrimination of the vulnerability to seawater intrusion, confining it only in proximity to the coastline. Conversely, GALDIT-SUSI divided the two sites in five classes of vulnerability ranging from very low to very high, stressing the higher vulnerability of lagoons and wetland for Epanomi and lagoons and rivers for the Po River lowland. GALDIT-SUSI is easy to apply and versatile, since it can be adapted to the specific hydrogeological setting of the area of interest. Moreover, GALDIT-SUSI can be further improved to deal with other salinization mechanisms.

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.

Seed germination biology of the Albany pitcher plant, Cephalotus follicularis

Cephalotus follicularis is an ecologically unique, taxonomically isolated and range-restricted carnivorous plant that occurs exclusively within vulnerable wetland habitats in coastal south-western Australia. Very little is known about the reproductive biology of this iconic plant species, particularly in relation to seed dormancy and the specific requirements for germination. This knowledge gap must be filled to facilitate the establishment of conservation and management initiatives for the species, as Cephalotus is increasingly impacted by habitat loss, alteration to natural hydrological and fire regimes and, in recent times, climatic change. This study aimed to determine the type of seed dormancy that the seeds of Cephalotus possess, determine the optimum conditions required for seed germination, and examine the storage behaviour of seeds. The seeds of Cephalotus are small (1.0 × 0.5 mm), lightweight (0.1 mg) and remain indehiscent within a wind-dispersed hairy achene. Results suggest that the seeds may exhibit some sensitivity to desiccation and appear to be short lived (&amp;lt;12 months) when stored at 23°C. Maximum germination was achieved after 16 weeks incubation at 15°C for seeds removed from the protective outer layer of the achene, while seeds retained within the protective outer layer displayed lower germination success. The post-ripening morphological changes in the embryo, limited response to gibberellic acid, and the long time period required for germination suggests that the seeds exhibit morphophysiological dormancy, with a fraction of seeds remaining dormant for a period of time post-dispersal. These results highlight the importance of limiting hydrological alteration within the few remaining habitats that continue to support Cephalotus, but to ensure its long-term protection, further research focusing on phenology and in situ recruitment is required.