http://hdl.handle.net/10498/6644 2026-05-10T01:28:26Z 2026-05-10T01:28:26Z Curcio, Andrea Celeste http://hdl.handle.net/10498/32880 2024-07-09T09:20:33Z 2024-05-24T00:00:00Z

Examining UAV-based LiDAR, Multispectral, Hyperspectral and Precision Photogrammetry Approaches for Tidal Salt Marsh Environments Curcio, Andrea Celeste Tidal salt marshes are one of the most productive and valuable ecosystems on Earth, providing multiple ecosystem services such as blue carbon trapping and coastal flood mitigation. However, this ecosystem is under serious threat due to human activities and rising sea levels. The purpose of this doctoral thesis is to adapt and evaluate various UAV-based methodologies for studying tidal marshes in the Bay of Cádiz, with the aim of optimizing these methods and enhancing the assessment, monitoring, and understanding of tidal marshes. This will enable the conservation and protection of these areas from current and future threats, with the intention of applying the results to other similar systems. The research focuses on fine-tuning remote sensing sensors for low-altitude applications in tidal marshes, developing a comprehensive methodology to optimize data collection and analysis, minimizing fieldwork while providing reliable and detailed spatial data. Several suitable approaches are generated and validated to enable the study of these valuable ecosystems, with the goal of offering new understandings and practical solutions for enhancing marine conservation. The achievements of this PhD Thesis aim to provide knowledge that both managers and researchers can use in decision-making for the protection, preservation, and management of the marine environment. The main characteristic that differentiates tidal salt marshes from other tidal environments is the dominance of a few species of vascular plants tolerant to marine influence. Understanding the environmental drivers controlling the distribution of this vegetation and improving tools to monitor changes in time and space, are urgent for successfully managing the survival of this threatened environment under scenarios of sea level rise (SLR). Surface elevation relative to mean sea level is critical for the performance of salt marsh plants, as differences of a couple of tens of centimetres can lead to a shift in dominant species. Thus, achieving maximum vertical precision when studying salt marshes is essential. Accurately assessing changes in ground level beneath the vegetation is essential for reliable estimates of aboveground biomass (AGB), which in turn allows quantification of the carbon sequestration potential of the system. An interdisciplinary approach that understands underlying mechanisms and creates extensive and high-quality field databases is needed to enhance marsh survival chances. These databases should cover essential factors such as sediment availability, precise topographic data, plant distribution, and vegetation productivity. However, the limited accessibility and the fragility of the soft soil in these environments complicate the application of traditional fieldwork techniques for data collection, which often are labour-intensive, time-consuming, and demanding, and can have negative impacts on marsh ecosystems. Their limited accessibility and the fragile structure of the soft soil hamper the easy development of fieldwork in this environment. Utilizing remote sensing techniques with unmanned aerial vehicles (UAVs) provides a significant opportunity to enhance our understanding of these complex habitats, minimizing the impact on the system, and thereby contributing to more effective management and conservation of these ecosystems. In the first application, we evaluated the optimal configuration of UAV sensors to guarantee data reliability and attain optimal outcomes using UAV-photogrammetry and UAV-LiDAR techniques for acquiring high-resolution topographic data. The results showed that UAV-photogrammetry provides the highest spatial resolution, although it requires extensive processing time, concluding that this technique is best suited for smaller areas. In contrast, UAV-LiDAR has proven to be a promising tool for coastal research. The point cloud collected by this sensor allows for the creation of accurate digital elevation models from lighter datasets, resulting in faster processing times compared to the UAV-photogrammetry technique. Nevertheless, distinguishing bare ground from vegetated surfaces in salt marshes was a challenge with UAV-LiDAR due to the similar LiDAR point cloud characteristics on both surfaces. To address this, we complemented the analysis with UAV multispectral data. By integrating multispectral (MS) and LiDAR data, the efficiency of the point cloud classification process increased significantly. The correlation between LiDAR measurements and field values was significantly improved by incorporating stable reference points (e.g., ground control points on fixed structures). The most reliable LiDAR sensor configuration for salt marsh applications, offering an appropriate balance between dataset size, spatial resolution, and processing time, has been identified. The present results demonstrate that UAV-LiDAR technology offers a suitable solution for coastal research applications where high spatial and temporal resolutions are required. The next objective of this Thesis was to map salt marshes at the plant species level using a high-resolution hyperspectral imaging system mounted on a UAV (UAV-HS). Remote sensing using UAV-HS in tidal marshes combines the advantage of high resolution in both the spatial and spectral dimensions, allowing for capturing variations at a very detailed scale. The combination of high spectral and spatial resolution facilitates the identification of the spectral signature of each plant species. Transformations were applied to the original spectral signatures to highlight the spectral characteristics of each species. The UAV-HS technique allowed for accurate differentiation of salt marsh plant species and, in combination with UAV-LiDAR data, facilitated the estimation of the corresponding elevation distribution range. The application of this technique to the Cádiz Bay salt marsh revealed the presence of two species of Sarcocornia spp. along with a class for Sporobolus maritimus. An additional class was created to represent overlapping areas with different proportions of Sarcocornia spp. and S. maritimus between low and medium marsh. The method successfully distinguished S. maritimus from mudflat areas colonized by microphytobenthos. The resulting species distribution map achieved up to 96% accuracy, with medium marsh species (i.e., Sarcocornia spp.) populating the elevation range of 2.30–2.80 meters LAT, a transitional zone spreading within the range of 1.91–2.78 meters LAT, and S. maritimus living within the range of 1.22–2.35 meters LAT. Establishing a method to assess the vulnerability of the salt marsh to SLR scenarios based on the relationship between elevation and species distribution could help prioritize areas for restoration efforts. While UAV-HS techniques offer highly customizable and easy operations, their application is limited by the large dataset generated, complex processing requirements, and computational demands, making them more suitable for smaller areas. Despite these challenges, UAV-HS offers valuable insights into specific events and invasive species distribution assessment. Although regular use may pose practical challenges, UAV-HS data holds significant promise in enhancing our understanding of coastal ecosystem responses and detecting subtle changes in plant species distribution through periodical monitoring. Finally, the performance of UAV-based techniques in estimating biomass density in salt marshes was evaluated by combining high-resolution LiDAR and MS datasets. The integration of this data allowed for the characterization of vegetation habitats through the analysis of Vegetation Indices (VIs) variability and high-resolution topographic information from LiDAR, significantly contributing to improving biomass estimation accuracy in these areas. Specifically, the Anthocyanin Reflectance Index 2 (ARI 2) along with the Digital Surface Model (DSM) facilitated the identification and differentiation of habitats dominated by different species (Sarcocornia spp. and S. maritimus). An analysis of the annual cycle of VIs revealed seasonality, with distinct seasonal changes in VIs for the two vegetation classes, suggesting different growth dynamics. Specific biomass models were developed for each habitat and season throughout the annual cycle, showing higher precision (up to 99%) compared to models that do not distinguish between the two habitat types. Differentiation of dominant salt marsh habitats revealed variations in biomass estimation trends, highlighting the impact of habitat-specific modelling on biomass seasonal dynamics. Sarcocornia reaches its maximum biomass in autumn, while S. maritimus does so in spring. The two species balance each other out, leading to minimal fluctuations in overall biomass levels throughout the year. The study revealed a seasonal pattern in the total AGB, with the highest biomass values occurring in summer and the lowest in spring, with annual variation accounting for only 9% of the total output. The reduction in AGB in spring could be attributed to increased substrate salinity and stress. The use of LiDAR and MS data from a UAV was essential to differentiate salt marsh habitats and develop their corresponding biomass models with exceptional accuracy. The methods proposed and presented in the current PhD investigation provide high-resolution data to characterize salt marsh environments and predict vegetation properties, reducing the need for invasive fieldwork. This approach, due to its ease of use, replicability, and cost-effectiveness, promises to be a valuable tool for studying marshes, understanding their dynamic patterns, and analysing their responses to climate change. These innovative tools can be applied in marsh ecosystems with typical mid-latitude zoning, significantly enriching our existing knowledge and transforming the methodology for studying and monitoring these environments. A deeper understanding of marsh dynamics can have a significant impact on their management and conservation. Additionally, the findings of this research can be used to design monitoring programs not only in various marsh environments but also in other coastal and continental habitats.

2024-05-24T00:00:00Z Mooser, Alexis http://hdl.handle.net/10498/32213 2024-06-18T07:34:13Z 2023-01-01T00:00:00Z

Beach Scenic Beauty versus Human Pressures and Natural Coastal Processes: an Innovative Approach with Case Studies from Spain, Bulgaria, France and Italy Mooser, Alexis The intensive and fast-growing use of beaches for leisure brought to the transformation, over the past decades, of many unspoiled coasts in unsustainable linear cities of strong economic relevance. Today, barely 15% of worldwide coastal sceneries remain intact from human intrusion. It is also estimated that roughly half of sand beaches may disappear by 2100 because of climate change consequences (coupled with the ongoing urbanization process). In others words, natural beaches are presently critically endangered and are disappearing. This remark is even truer for beautiful coastal areas since their capacity of attracting visitors, i.e., Scenery, is one of the five parameters of greatest relevance in beach choice. With that in mind, the emphasis of this Ph.D. project was placed on three major issues: Scenic beauty, Scenic sensitivity and Beach management. For these purposes, several coastal sectors that sum a total coastal length 3000 km along four distinctive European countries, were chosen: Spain (Andalusia and the Balearic Islands), northern France, Bulgaria and southern Italy, all standing out for exhibiting a wide variety of coastal sceneries. In the quest of identifying most attractive sites slightly or not affected by human activities, a total of 149 sites, mainly located in remote areas, were selected after field assessments. Scenic beauty was evaluated by means of the Coastal Scenic Evaluation System (CSES), a semi quantitative method based on 26 physical and human parameters and fuzzy logic mathematics. Respecting.Scenic sensitivity a method was proposed to determine sensitivity to human pressures and natural processes in a climate change context, firstly tested in Andalusia, Spain (29 sites, Chapter 2) and, then, applied in the Balearic Islands, Spain (52 sites, Chapter 3), and Bulgaria (16 sites, Chapter 4). Beach management implications on coastal scenery was the focus of the research carried out in France (16 sites, Chapter 5) and Italy (36 sites, Chapter 6). Realizado en el marco de un convenio con la Universidad de Nápoles "Parthenope" (Università degli Studi di Napoli Parthenope en Italia)

2023-01-01T00:00:00Z Almón Pazos, Bruno http://hdl.handle.net/10498/31667 2024-04-10T09:22:43Z 2023-07-03T00:00:00Z

Revisión taxonómica de las especies ibéricas de cangrejos ermitaños (DECAPODA: ANOMURA: PAGUROIDEA) y sus relaciones filogenéticas Almón Pazos, Bruno Traditionally, the study of hermit crabs has been based on the description and comparison of morphological characters that are sometimes difficult to assess, which in many cases has led to difficulties in clearly delimiting species. The morphological complexity of the group (where practically all body appendages are considered characters with taxonomic value), the intrinsic variability of each species, as well as their characteristic body asymmetry, has resulted in many cases in unclear delimitations of taxa, discrepancies about the validity of certain taxonomic categories and, in general, a knowledge about the group that still needs to be further clarified. The combination of morphological studies with molecular phylogeny analyses provides a more global view of the kinship relationships between the different species and allows us to review the relative importance of certain characters used in their delimitation. This work is structured in such a way that, firstly, specific results obtained from the revision of all the available specimens are presented. This is followed by the more general studies, which include an important part or the totality of the species studied. This structure is reflected in the form of sections, in order to facilitate access to the specific chapters that comprise them. The first section includes three chapters, the first two dedicated to the morphological study of several new species of the genus Diogenes and the redescription of Diogenes pugilator, as well as the description of a new species of the genus Pagurus from northwestern Africa. The second section focuses on the taxonomic revision of the genus Anapagurus, from an integrative perspective of the different sources of information, mainly morphology and molecular characterisation of the species. The third section is devoted to updating the list of hermit crabs from the Iberian Peninsula and nearby areas. All these species are included in an annotated checklist, that is complemented with distribution data and references, as well as the study of their phylogenetic relationships. The analysis includes 374 new sequences from a total of 54 Iberian species, 8 from neighboring areas and 55 sequences obtained from GenBank for comparison purposes. The information generated specifically for this study is the first molecular information available for 21 of these species, which represents a substantial step forward in the updating of the genetic catalog of this group and therefore in the development of the molecular tools used in the delimitation of species. The fourth and final section focuses on the study of the live colour patterns of Iberian species. These patterns are considered very characteristic and defining of the species in the case of hermit crabs, although the information available so far was generally scarce. A special effort has been made to try to collect live specimens of each species, photograph and draw them. When it was not possible to collect them in vivo, we used existing photographs, where some of the morphological details allowed us to confirm the identity of the species. With all this information, colour plates of 45 species have been produced to accompany their descriptions, where these characteristic patterns have been described, so that this chapter can be considered a proto-guide to field identification. Throughout this study we have been able to see how the taxonomic revision of the different genera has thrown up some questions that only after further revisions have we been able to begin to elucidate. We have also seen how, in the world of hermit crabs, the displacement of species outside their distribution range occurs, although it is not always possible to know if this is happening at present or if they have gone unnoticed, but it is clear that in the future there will be more changes, incorporations and discoveries of new species. This work is, therefore, a great step forward in the knowledge of this group in the Iberian Peninsula and nearby areas, as well as in the clarification of its taxonomy.

2023-07-03T00:00:00Z Sayed Ahmed, Abdelrhman Muhamed Fahmy http://hdl.handle.net/10498/29204 2023-09-14T00:33:14Z 2023-01-01T00:00:00Z

Durability problems of the archaeological construction materials in aqueous and subaerial environments, with applications for restoration and conservation in Egypt and Sudan Sayed Ahmed, Abdelrhman Muhamed Fahmy The main objective of the study was to identify and assess the conservation problems of the building materials of each case study and compare the aggressive impacts of each environment on the sustainability of the construction materials. Carefully, the construction materials (limestone, sandy limestone, sandstone, lime mortars, gypsum, hydraulic lime mortar/roman mortar) were selected from different archaeological sites with different environmental conditions in Egypt and Sudan (desert: Sahure?s pyramid and pyramids of Meroe; urban/agricultural: Nero/Ramses II Temple; coastal: Anfushi?s Necropolis; and fluvial: Abaton/Osiris Temple). To achieve this goal, field observations, analytical (X-ray diffraction, X-ray fluorescence, Raman spectroscopy, UV-Vis spectrometry), microscopic (binocular microscope, polarizing microscope and scanning electron microscope), mapping (AutoCAD, ArcMap 10.8, SeaDAS, QGIS), and physical and mechanical testing investigations were carried out. Furthermore, open-access satellite lenses were used for the detection and assessment of the archaeological sites and their risks, and, the deterioration patterns of each case study were recorded through decay mappings. Finally, to preserve the lime mortar surfaces, a newly synthesized nanomaterial of SiO2-TiO2 NPs/TEOS was applied and tested. The results showed the severity of each factor on the construction materials. In this sense, Sahure?s pyramid was affected mainly by climatic and environmental factors, earthquakes and the inner composition of the building materials. Nero/Ramses II Temple showed its susceptivity mainly from the salt attack which came from the contaminated sources of water around the temple. Water intrusion, earthquakes, storms, and heavy rains factors attacked Anfushi?s Necropolis severely. Abaton/Osiris Temple was decayed because of Nile water fluctuations impact and the inner weakness of the temple sandstones. In Sudan, the pyramids of Meroe were damaged because of the sand dunes and wind forces, in addition to the flooding risks. Finally, and concerning to the heritage conservation, the research exhibited the efficacy of the multifunctional 3% and 5% SiO2-TiO2 NPs/TEOS in the consolidation and improvement of the physical and mechanical ancient lime mortars.

2023-01-01T00:00:00Z