Coastal Dunes Research Articles

When Grinnellian generalist species seem to be more sensitive to altered habitats than specialists: the case of Orthoptera communities settled in coastal dunes

Summary Numerous examples documented that species generalists for habitats are less sensitive to altered environment than specialists. However, in arid environments, an example indicated an opposite trend due to special adaptive features of organisms. We tested this hypothesis in the case of grasshopper communities, settled in the coastal dunes of northeast Algeria, as several aspects of dunes constitute stressful conditions resembling those of deserts. To define the dune-specific grasshoppers (specialists) and the dune non-specific ones (generalists), we applied the indicator value index to monthly samplings conducted in four coastal dune sites and 12 other sites of grasslands, fallow lands and scrublands in the same area. The degree of disturbance of each coastal dune site was deduced from the alteration of plant cover and richness. We investigated the relation between the specialist and generalist richness and abundance with the degree of perturbation using linear regressions. Results showed contrasting patterns for specialist and generalist grasshoppers: both abundance and richness of the generalists significantly decrease with an increasing degree of perturbation, while specialists show little to no changes. The higher resistance of specialist grasshoppers over generalists toward disturbance was not linked to the plant dune-specialists or generalists. This study is one of very few illustrating the relative resistance of specialized species toward disturbance.

Morphological Performance of Vegetated and Non-Vegetated Coastal Dunes with Rocky and Geotextile Tube Cores under Storm Conditions

Coastal dune restoration projects are increasingly seen as a means of protecting the coast against storms, especially with the use of natural (plants), artificial (geotextile tube cores) and hybrid (plants and geotextile tube) elements. As geotextile tube cores have been found to negatively affect dune and beach natural morphodynamics, rocky cores are thus seen as a potential alternative. We carried out laboratory experiments to compare the performance of dunes with rocky cores, geotextile cores, and both types when coupled with planted vegetation. We investigated these elements in the context of scaled mild, moderate, and intense storm conditions. The results showed that dunes with either type of core lost more sand than dunes without cores. The addition of plants generally reduced the erosion across the various options, but most strongly for rocky cores under mild and moderate storm conditions. We also found that dunes with a high density of plants were best for intense conditions. Overall, the use of rocky dune cores, when coupled with plants, is the most suitable and sustainable alternative option in hybrid engineering projects.

Limekiln services soil enrichment and water retention of an Early Islamic Plot-and-Berm groundwater-harvesting agroecosystem in coastal dunes near Caesarea, Israel

Limekiln services soil enrichment and water retention of an Early Islamic Plot-and-Berm groundwater-harvesting agroecosystem in coastal dunes near Caesarea, Israel

Detection of Yucca gloriosa in Mediterranean coastal dunes: A comparative analysis of field-based sampling, human interpretation of UAV imagery and deep learning to develop an effective tool for controlling invasive plants

Using UAV imagery is a powerful method for monitoring invasive alien plant species (IAPs), particularly when combined with automatic image analysis conducted by artificial intelligence. To this end, we conducted a pilot study on Yucca gloriosa, an invasive species of coastal dunes spread in central Italy. Specifically, we assessed the agreement in quantifying Y. gloriosa cover between field-based sampling and human visual screening of UAV images captured at different altitudes. Additionally, we examined the concordance among different operators both before and after a training procedure, comparing a simpler and quicker approach (referred to as the “envelope” method) against a seemingly more precise but time-consuming method (referred to as the “leaf by leaf” method). In our current study, we discovered a good concordance not only between operators and field sampling but also among operators, particularly when using the “envelope” method. Furthermore, we assessed the performance of deep learning in identifying Y. gloriosa plants in UAV images compared to visual identification by human operators, achieving an overall accuracy of 96 % for images taken at an altitude of 35 m. Our findings suggest that UAV imagery may serve as a valid alternative to field-based sampling for monitoring IAPs, especially when dealing with plants like Y. gloriosa, which have distinctive morphological characteristics that facilitate identification. Consequently, mapping Y. gloriosa on Mediterranean coastal dunes can be effectively accomplished using UAV images, even though an automated machine-based approach, thereby expediting and enhancing the reliability of alien species monitoring and management.

Disturbance tolerance of arbuscular mycorrhizal fungi: characterization of life-history strategies along a disturbance gradient in a coastal dune ecosystem

Disturbance tolerance of arbuscular mycorrhizal fungi: characterization of life-history strategies along a disturbance gradient in a coastal dune ecosystem

Temporal and spatial variation in extrafloral nectar and associated ants in Canavalia rosea (Fabaceae) on coastal dunes along the Gulf of Mexico

ABSTRACT Extrafloral nectar production can vary depending on the structure of the plant in which it is found, as well as environmental conditions. This can in turn influence plant-ant interactions. We evaluated the role of extrafloral nectaries of Canavalia rosea as ant attractants in a coastal zone of the Gulf of Mexico. We compared the productivity of the extrafloral nectaries present on leaves and inflorescences, as well as between day and night, and described the associated ant community. Nectar volume and concentration were higher in inflorescences than in leaves, and the rate of ant visitation was higher in inflorescences during the day. These results suggest congruence with the Optimal Defense Hypothesis. Nectar volume was generally greater during the night in both structures, but sugar concentration did not differ between day and night. We found a turnover in the ant species visiting C. rosea, with S. geminata being the most abundant species. The extrafloral nectar of C. rosea attracts several ant species and probably other arthropods, providing a valuable resource in a stressful system.

Analysis of Sedimentary Morphology and Forming Environment of Coastal Dune in Donghai Island of Zhanjiang, China

Analysis of Sedimentary Morphology and Forming Environment of Coastal Dune in Donghai Island of Zhanjiang, China

Investigating the Potential of the Tree-ring δ18O Time Series of Pinus thunbergii in the Dendroarchaeological Study

The main content of dendroarchaeology is to assign the exact calendar year to each tree ring in archaeological wood. Each tree ring can be assigned a year because the pattern of ring-width time series (hereafter, ring-width chronology) is unique for each time period and the same tree species share the pattern. However, the lack of agreement between ring-width chronologies of <i>Pinus thunbergii</i> compared to other tree species makes it difficult to use the chronologies for dating. This study was conducted to verify the dating possibility of archaeological woods using tree-ring δ<sup>18</sup>O time series (hereafter, tree-ring δ<sup>18</sup>O chronology) instead of ring-width chronology. For the study, 7 <i>P. thunbergii</i> were selected from coastal dunes, and the ring-width and tree-ring δ<sup>18</sup>O chronologies were compared. The results showed that the agreement between ring-width chronologies were large statistical deviations (<i>t</i>-value: 0.6~12.5 / G value: 38~70%) as much as difficult for dating. On the other hand, the tree-ring δ<sup>18</sup>O chronologies showed reliable agreement between them as statistically (<i>t</i>-value: 4.3~6.4 / G value: 77~84%) and visually. Based on the results, it has been verified that the dating possibility of archaeological woods for <i>P. thunbergii</i>, which is a difficult tree species for dating in dendrochronology, can be greatly improved if the tree-ring δ<sup>18</sup>O chronology is applied.

Effects of TiO2 ultraviolet filter and sunscreens on coastal dune plant performance and competitive interactions

Ultraviolet filters (UVFs) added to sunscreens (SS) are emerging contaminants in marine environments due to their adverse effects on organisms and ecosystems. UVFs have also been detected in beach-dune systems, but their influence on resident organisms has not been explored yet. Native plants are fundamental components of coastal dunes, and these ecologically/economically important systems are currently among the most threatened globally. Thus, understanding whether UVFs may act as threats to dune plants is crucial. This field study evaluated and compared the effects of titanium dioxide nanoparticles (nTiO2), one of the inorganic UVFs most commonly added to sunscreens, and those of a commercial sunscreen product containing it (SS-nTiO2) on the performance of adult dune plants of a native (Thinopyrum junceum) and a non-native invasive species (Carpobrotus sp. pl.) and their competitive interactions at environmentally realistic concentrations. The effects of nTiO2, SS-nTiO2 and of a sunscreen product containing just organic UVFs (SS-OF) on early life stages of T. junceum were also examined. Ti bulk content in sand and plants at the study site ranged from 970 to 1069 mg kg−1 and from 2 to 7.9 mg kg−1, respectively. Thinopyrum junceum adult plants periodically exposed during the summer season to seawater contaminated by SS-nTiO2 produced less biomass than un-exposed plants and nTiO2 exposed plants. nTiO2 and SS-nTiO2 reduced the capacity of T. junceum to control the spread of Carpobrotus. Both SS-nTiO2 and SS-OF reduced seedling emergence in T. junceum whereas nTiO2 did not. These results demonstrated that the periodical exposures of native dune plants to sunscreens could reduce their establishment success and growth and favor invasive plant spread potentially resulting in community structure changes. They also emphasize the need to assess the phytotoxicity not only of single UVFs but especially that of complete sunscreen products to design more eco-friendly formulations in the future.

Asymmetrical gene flow between coastal and inland dunes in a threatened digger wasp

Asymmetrical gene flow between coastal and inland dunes in a threatened digger wasp

Causes and effects of coastal dunes erosion during storm surge Axel in January 2017 on the southern Baltic Polish coast

The study is dedicated to researching the storm surge Axel, the largest on the South Baltic coast in the 20th and 21st centuries. This unique event resulted in a very large erosion along the whole Polish Baltic Sea coast in January 2017 (max. HSL = 1.65 m, the average for the coast 1.36 m). Storm surge effects on the coast were followed based on field observations of dune retreat and analysis of hydrodynamic and meteorological parameters of the surge and its passage through the Baltic Sea. The material of dune erosion was collected based on cross-shore profiling of almost every 1 km, along the whole Polish sand barrier coast, before and after this storm. The work also studies the parameters of smaller storm surges from the end of 2016, which caused the lowering of beaches and dune erosion. A relationship was observed between erosion, and beach height and sea level (SL). The higher the beach, the lower the erosion that occurred. The average dune toe retreat was 5.1 m, and the largest exceeded 9–19 m (max. 42 m). The most important for dune erosion was the height of run-up, beach height and shore exposition for a surge. The largest dune erosion was observed during the heaviest SL with wave run-up higher than 3.8 m above mean sea level (AMSL). Each coast section was eroded, which also caused losses in infrastructure.

Prevalence and Distribution of Nematodes from Coastal Sand Dunes in the Iberian Peninsula

Nematodes are a large and diversified zoological group with a wide global distribution, being able even to be present in habitats with extreme conditions. Although coastal dunes can be considered as an adverse environment for these animals, numerous species are discovered there. In general, these small animals present some morphological characteristics, which provide them a high adaptability to these habitats and the ability to reach a wide distribution. In this study, a total of 222 sample sites of coastal sand dunes have been studied in order to know the nematofauna of these habitats. Thus, 42 coastal dunes from three geographical areas of the Iberian Peninsula coast (Atlantic coast, southern Mediterranean coast, and northern Mediterranean coast) were examined. A total of 120 species of nematodes were found, belonging to eight orders. The results showed the higher prevalence of the species belonging to the order Rhabditida, which were present in 84.2% of the sand dunes studied, most of them belonging to the family Cephalobidae with 42 species, while the order with lower prevalence was the order Enoplida appearing only in one dune (0.9%). The classification of nematofauna by trophic groups showed that bacterial feeders, omnivores, hyphal feeders, and plant feeders shared a high prevalence (83.3%, 40.5%, 34.2%, and 32.8%, respectively), while predators, unicellular eukaryote feeders, and substrate ingesters account for less than 11%. A list of the found species, prevalence, and trophic groups is included.

Back to the future: Using ancient Bere barley landraces for a sustainable future

Societal Impact StatementBere is an ancient barley (Hordeum vulgare L.) that was once widely grown in northern Britain, where its ability to grow on poor soils and under challenging climatic conditions made it a valuable staple. By the end of the 20th century, Bere had largely been replaced by higher‐yielding modern varieties and only survived in cultivation on a few Scottish islands. This article reviews the recent revival of Bere, driven by its use in high‐value food and drink products and multidisciplinary research into its genetics, valuable sustainability traits and potential for developing resilient barley varieties.SummaryIn Britain, modern cereal varieties have mostly replaced landraces. A remarkable exception occurs on several Scottish islands where Bere, an ancient 6‐row barley (Hordeum vulgare L.), is grown as a monocrop or in mixtures. In the Outer Hebrides, the mixture is grown for animal feed, and cultivating it with traditional practices is integral to the conservation of Machair, an important coastal dune ecosystem. In Orkney, Bere is grown as a monocrop, and in situ conservation has recently been strengthened by improved agronomy and new markets for grain to produce unique foods and beverages from beremeal (flour) and malt. In parallel, a recently assembled collection of British and North European barley landraces has allowed the genotypic and phenotypic characterisation of Bere and several associated multidisciplinary studies. Genotyping demonstrated Bere's unique identity compared with most other barleys in the collection, indicating an earlier introduction to Scotland than the Norse settlement (c. 9th century AD) suggested previously. Valuable traits found in some Bere accessions include disease resistance, an early heading date (reflecting a short period from sowing to harvest), the ability to grow on marginal, high pH soils deficient in manganese and tolerance to salinity stress. These traits would have been important in the past for grain production under the region's challenging soil and Atlantic‐maritime climatic conditions. We discuss these results within the context of Bere as a genetic, heritage and commercial resource and as a future source of sustainability traits for barley improvement.

An Integrated Approach between Multispectral Satellite Images and Geophysical and Morpho-Topographic Surveys for the Detection of Water Stress Associated with Coastal Dune Erosion

Coastal erosion occurs due to different processes involving physical and ecological systems. One of these factors is the degree of water stress experienced by dune vegetation. While healthy dune vegetation can help to stabilize the dune systems, water-stressed vegetation can instead enhance dune erosion. In this study, remote sensing techniques were used to monitor the water stress affecting the dune vegetation in dune systems along the alluvial plain of the Chiatona coast (Apulia, Southern Italy) located on the Ionian Arc. Multispectral satellite data from Landsat 8/9 and Sentinel-2 were used to assess the water stress at different spatial scales over a 4-year monitoring period from 2019 to 2023. The normalized difference vegetation index (NDVI) and the normalized difference moisture index (NDMI) were used to identify dune surfaces that were experiencing water stress. Furthermore, a terrestrial laser scanner and LiDAR data were acquired at different temporal ranges in areas affected by water stress to highlight coastal changes in areas associated with unhealthy dune vegetation. A large drop in NDVI values was observed in May 2020 due to the occurrence of coastal fires in some parts of the Chiatona coast. Geoelectrical surveys were conducted to investigate if coastal fires were capable of saline groundwater contamination, potentially enhancing dune erosion in these areas. The joint analysis of remote sensing, topographical, and geoelectric data showed that water stress reduced the amount of healthy dune vegetation, triggering dune deflation processes that resulted in increased coastal erosion rates, while also leading to the saline contamination of groundwater.

Analysis of Topographic Surveys with RPAS in Steep Coastal Dunes

The current use of photogrammetric systems with RPAS (remotely piloted aircraft systems) for the acquisition of topographic data in every type of coastal area has the benefit of a low risk for the personnel involved, good precision, increased productivity, and lower costs. However, their accuracy has not yet been researched in areas with steep terrain. In this paper, we study dune areas with slopes between 20 and 30%. The objective of this work is to examine the influence of the inclination of both the flight and the camera and to compare the results with those obtained using constant-height flights. With the data collected during three field campaigns, a total of 18 cases were studied. Among the results obtained, in the case of the horizontal flights, a vertical error of 0.048 m was detected for a 0° inclination of the camera versus an error of 0.086 m for a 10° inclination, thus an increase in the camera inclination decreased the accuracy by 44%. Moreover, the flight inclination did not lead to a significant reduction in the error. Therefore, as a main conclusion, the planning of horizontal flights as well as the non-tilt of the camera are recommended.

COASTAL DUNES CHANGES ALONG THE WESTERN COAST OF EUROPE

Coastal dunes are natural barriers buffering storm waves, protecting coastal communities from flooding and rising sea level, and providing a valuable source of biodiversity for the surrounding environment. Significant dune erosion caused by storm waves and high water levels generally takes place over hours or days, while post-storm recovery can take years or decades (Houser et al., 2015). Although coastal dunes have received quite a lot of attention over the last decades, knowledge gaps remain, and our understanding and predicting capacity of long-term (years to decades) coastal dune evolution remain limited. The large diversity of coastal dunes along the Atlantic coast of Europe and the sequence of extreme storms observed during the 2013/14 winter, considered as the most energetic storms since at least 1948 (Masselink, 2016), represent a unique opportunity to study the spectrum of coastal dune response and recovery from an extreme winter.

PHYSICAL MODELLING OF SOLITARY WAVE OVERTOPPING IN THE PRESENCE OF A COASTAL DUNE

Oceanic underwater disturbances are associated with submarine landslides, volcano eruptions, or seismic activity occurring below or near the ocean basin, which can produce tsunami, which have a small amplitude in deep water with a very long wavelength, so they generally pass unnoticed offshore (Robke and Vott, 2017). These types of tsunami waves can cause massive damage or failures to coastal structures (Kato et al., 2007). From the field surveys after the 2004 Indian Ocean and 2011 Japanese tsunami, it was revealed that natural coastal features such as dunes, dense vegetation, and a combination of dunes with vegetation, acted as natural buffers and provided protection to infrastructure and communities further landward (Fritz and Borrero, 2006; Wijetunge, 2006; Murthy et al., 2012; Wijetunge, 2012). The role of coastal forests, such as mangrove vegetation, on tsunami run-up and inundation reduction, have been extensively studied by many researchers with physical and numerical modeling (Husrin et al., 2012; Yao et al., 2015; Esteban et al., 2017), but not the influence of coastal dunes in offering direct protection. Hence, the present research aims to investigate the mitigation of tsunami run-up and overtopping by coastal dunes.

NATURE-BASED SOLUTIONS ON MEGA-BIODIVERSE COASTS: EXPERIENCES AND CHALLENGES IN MEXICO

Coastal ecosystems in tropical areas have a very complex biodiversity where, in a small space, a large number of species is concentrated. The most common tropical ecosystems, coral reefs, seagrass beds, beaches, coastal dunes, coastal lagoons and mangrove forests, are found along the Mexican coast, the target of this analysis. Depending on geological, climatic, and nutrient conditions, some, or all of these ecosystems may be present in any one coastal unit. Within a very small distance, it is common to find several of these ecosystems which can be preserved or altered by human use. Based on the work by Silva et al., (2021), through the application of the DESCR framework (Drivers - Exchanges - State of environment – Consequences - Responses, Silva et al., (2020)) analyses were made of more than 20 Mexican case studies to assess the effectiveness of nature-based solutions.

Exploring Controls on Coastal Dune Growth Through a Simplified Model

AbstractProcess‐based morphodynamic models can be useful in understanding coastal dune responses to disturbances, as well as possible evolutionary patterns. To this aim, we employ Duna, a simplified 1D morphodynamic model, to assess the influence of dune morphology (height and slope) on sand transfer and deposition across the dune profile for different beach widths and wind incidence angles through idealized experiments. Simulations of real conditions show good model performance, both in wind flow reproduction and in topographic change along the dune profiles tested. The idealized experiments show that wind speed increases and sand accumulation decreases logarithmically with dune height and linearly with stoss slope along the dune profile. Fetch and cosine transport limiting parameters are reflected in the sand accumulated windwards from the toe, while sand transfer to the dune appears controlled by multiple factors; the higher the dune and/or the narrower the beach, the likelier that maximum accumulation occurs under oblique winds. Results point to two different types of evolution for high dunes. Either the vegetation is dense enough to maintain the stoss position, in which case vertical growth near‐ceases and seaward progradation is promoted, or the stoss is eroded and landward retreat dominates, in which case sand transfer to the crest and lee continues as a mixture of low input from the beach and recycled sand from the stoss.

Aeolian Landforms in the White Sea Coast: a Review of Classification and Spatial Distribution

This research provides classification and analysis of the spatial distribution of the Holocene aeolian landforms within the White Sea Coast. We identified 5 types of secondary dunes based on the interpretation of detailed satellite images, topographic charts and analysis of literary sources: foredune plains and beach ridges plains, cliff-top dunes, blowouts and parabolic dunes, transgressive dunefields, sand sheets. The dunes were formed mainly from the Middle-Late Holocene. They gravitate towards sandy shores, where post-glacial uplift rates didn’t exceed ~3 mm/year during the Middle-Late Holocene. The coastal dunes were formed in connection with sediments, which entered the coastal zone with solid river flow and from selective erosion of glacial deposits. The rhythms of aeolian processes activation in different parts of the White Sea Coast were non-synchronous.