Browsing by Issue Date, starting with "2022-07-13"
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- Exploring chlorophyll-a satellite derived data to characterise the coastal waters of the south of PortugalPublication . Muche, Endalkachew Yeshewas; Cristina, Sónia; Cordeiro, ClaraThe chlorophyll-a (Chl-a) concentration can be used as the main indicator of the productivity, trophic condition, and proxy of phytoplankton biomass in coastal, and oceanic waters. This ecological indicator will provide useful information for reliable monitoring systems and government policy (e.g., European directives); however, assessment of Chl-a using in situ measurements in coastal and oceanic waters has some economic challenges and gives a restricted view of the dynamics of the phytoplankton. To overcome this limitation this study used Chl-a datasets from the Copernicus Marine Environment Monitoring Service (CMEMS), that provide merged multi-sensor ocean colour products. This study aimed to characterise the inter-annual variability of the Chl-a concentration retrieved by multi-ocean colour sensors data and relate these variabilities to the coastal environmental changes in five stations in the south coast of Portugal. Statistical analyses were performed to help the understanding and the characterisation of Chl-a at the coastal water stations along the southern Portugal coast based on 17 years of data (2002-2019). In addition, a comparison between Chl-a and physical (sea surface temperature (SST)) and chemical (nutrients) parameters were made to understand the inter-annual variability in these coastal waters. The extracted Chl-a values in the study area showed a seasonal cycle where the Chl-a is triggered in early spring. A clear negative relationship between Chl-a and SST was found in all stations. In the study area, a positive correlation was found between Chl-a and nutrients (NH4+, NO3-, PO4-3, and SiO4-4). Results show that SST and nutrients influence the Chl-a concentration availability in the study area. The Chl-a retrieved by satellite data reveals to be an efficient alternative tool and valuable approach to study environmental conditions of the coastal water, especially in response to eutrophication, which is the common management issue in coastal waters.
- Importance of physical health for European millennials: impact of COVID-19 on perceived importance of physical health in the futurePublication . Letz, Jan Niklas; Ferreira, Lara NThis work addresses the lack of knowledge about whether the Covid-19 pandemic will lead to a change in attitude toward physical health. The aim was to assess the impact on the perceived importance of physical health among European millennials. For this purpose, an online questionnaire was conducted. The items developed intended to measure the general importance of physical health, the specific perceived importance of physical health, and changes in attitudes towards physical health among the target group. The quality criteria of the questionnaire have been statistically verified. For data collection, a link to an online version of the questionnaire was initially sent to directly accessible persons of the respective target group, with the request to forward this link to further individuals belonging to the target group. This procedure led to a non-randomised sample in this research. The final evaluation was based on a sample of 188 respondents, of which 116 were female, 70 male, and two respondents indicated non-binary as their gender. With 158 participants who grew up in Germany, the sample only represents a section of the European region. The following conclusions can be drawn from the data collected: Physical health is important for European millennials. The Covid-19 pandemic has a changing impact on attitudes. This study shows that physical health is important for European millennials and Covid-19 further increased this attitude. While a tendency in the attitude toward the perceived importance of physical health can be observed, however, the trend is statistically not reliable. It is recommended to further develop the developed survey instrument to obtain more reliable data on the perceived importance of physical health and apply additional methods that would benefit the detection of the impact of the Covid-19 pandemic on this construct.
- Geomorphological and statistical analysis of the dune changes in Lido di Classe (Ravenna, Italy) based on remote sensing techniquesPublication . Faelga, Regine Anne; Giambastiani, Beatrice M.S.; Cantelli, Luigi; Silvestri, SoniaCoastal dunes are well-known for their significance in providing vital ecosystem services. However, its highly dynamic nature and its exposure to climatic and anthropogenic pressures make them one of the most vulnerable geologic features along the coastal zones worldwide. On a local perspective, the coast of Ravenna – a low-lying coastal zone located along the Northern Adriatic Sea in Italy, is among the areas that are subjected to increasing environmental risks such as coastal erosion, storm surge, groundwater and soil salinization. Restoration initiatives have been implemented in some of the protected dune areas to combat against impending risks. This thesis aimed to contribute to the assessment of the dune restoration project in the protected natural area of the Bevano River mouth in Ravenna using UAV monitoring surveys from 2016 to 2021. The restoration measure included two windbreak wooden fences that were installed in front of the dune foot and parallel to the coast to stop wind and facilitate sand deposition and accumulation. Primarily, the objective is to assess the impact of the 2016 restoration project in the dune development in terms of sand volume changes by utilizing the Structure from Motion (SfM) photogrammetry and the Geomorphic Change Detection (GCD) toolset. Next is to establish a systematic workflow for UAV data processing and elevation data analysis that is suitable for sediment volume calculations. Last is to explore the utility of orthomosaic images for vegetation change detection in order to determine other contributing factors to the overall geomorphology of the dune ridge. For the methodology, the UAV topographic survey, coupled with GPS ground survey using Real-time Kinematic (RTK) positioning, were carried out from 2016 to 2021 in order to assess the geomorphological evolution of the area over time. SfM photogrammetry was utilized to generate and classify the point cloud and orthomosaic images for each survey year using Agisoft Metashape Professional. The classified ground points were interpolated in ArcMap to create Digital Elevation Models (DEMs), while the orthomosaic images were utilized to confirm the possible sources of data noise in the model and assess vegetation changes. GPS points and profiles were used to validate the elevation models. The volumetric changes in sediment storage and error analysis were calculated using the DEM of Difference (DoD) approach under the Geomorphic Change Detection (GCD) extension toolbar in ArcMap. The results show that sand accumulation was observed along the dune foot where the wood fences were established. The following changes have also been observed - progradation of the front dune, development of insipient dunes, decrease in slope stoss, decrease of blowout features due to increase in vegetation colonization. There is also an increase in vegetation and debris cover within and near the wood fences. Overall, it can be concluded that the windbreak fence has proven to be an effective intervention to prevent dune erosion since significant geomorphological changes and vegetation colonization have occurred based on the comparison between the 2016 and 2021 data. This is despite numerous factors affecting the overall sediment budget dynamics in the study area. The GCD toolset can be an effective monitoring tool for coastal dunes provided that the sources of uncertainties are well accounted for. In a coastal management perspective, the results of this thesis can supplement in showcasing the importance of implementing sand trapping fences and limiting debris cleaning as nature-based solutions to combat dune degradation along the coastal zones of Ravenna. The proposed systematic workflow in this research can also be explored in creating transferable guidelines to relevant stakeholders in implementing its integrated coastal zone management (ICZM). The manuscript has a total of five (5) chapters. Chapter one includes a comprehensive literature review on the basic principles relevant to coastal dune geomorphology and the gaps that this study would like to fill in. It also includes the information about the scope and area of the research. Chapter two provides the in-depth details about the methodology of the study that includes the data acquisition and processes, the implemented workflow for SfM, DEM creation, quality check and assessment, and vegetation analysis using the high-resolution orthomosaic images. All the results are presented in Chapter three, while the detailed discussions are in Chapter four. Conclusions and recommendations are presented in Chapter five.
- Coastal flooding risk assessment at Garachico: Canary IslandsPublication . Barros, Jose Eduardo Carneiro; Hervas, Juan Garzon; Lara, Javier Lopez; Plomaritis, TheocharisCoastal Hazards are a topic of great interest for managers, given the possible socio-economic consequences associated with them. Specifically, investigating coastal flooding is particularly critical to assess the risk related to extreme ocean events. Also, climate change impacts will potentially increase the risks associated with it. In this sense, a critical parameter to predict the occurrence of flooding in vulnerable areas is the wave runup. In this study, the estimation of wave runup and overtopping were based on several published empirical formulas, derived from field and laboratory experiments, mainly depending on the oceanographic parameters, and the geomorphology of the beach or geometry of the structure. This study aims to 1) investigate the ability of expressions found in the literature to compute wave runup into a rocky and steep bottom at Garachico Island (Spain), by comparing it with past historical events; and 2) assess the risks of coastal flooding based on return periods (response approach) for extreme events using the tilted bathtub approach for evaluating the flooding extension, considering current and future conditions. Moreover, the effect of sea-level rise on different IPCC (Assessment Report 6) scenarios were evaluated. This study will contribute to the development of a methodology to assess coastal flooding, especially for areas characterized by rocky and steep bottoms, which represents a gap in the literature.
- The spatial distribution of the common dolphin, Delphinus delphis, along the Portuguese mainland coast and their interaction with the purse seine fisheryPublication . Brouder, Sarah; Gonçalves, J. M. S.; Marçalo, AnaThe common dolphin, Delphinus delphis, is the most abundant cetacean species along the Portuguese mainland coast and are faced with many anthropogenic threats. Over the past decade, intense fishing practices have contributed to a decline in the availability of their main prey, the sardine. Furthermore, the high Purse Seine Fishing (PSF) activity has raised concern over the level of by-catch along the coast. The purpose of the study is to (i) investigate the distribution of the common dolphin along the Portuguese mainland coast, and (ii) to estimate the overlap between the PSF effort and the common dolphin’s distribution. The study uses sighting data from 2005-2020 to identify dolphin hotspot areas. In addition, the study analyses changes in their offshore distribution across different time periods. Finally, the study overlaps Automatic Information System data of the PSF with common dolphin distribution data, in order to identify high by-catch risk areas. The outputs of the study identify major common dolphin hotspots along the central and southern Portuguese mainland coast, which coincide with important fishing ports and geographic features. Furthermore, the common dolphin was found to occur significantly further from the coast during from 2013-2016 (p-value < 0.05), which corresponds with a period of particularly low sardine biomass. Finally, the by-catch risk assessment reported high risk areas off the western Algarve, particularly near important fishing grounds. The study highlights the major common dolphin hotspots and potential conflict areas with the PSF. These results can be used by managers to inform conservation measures and for the sustainable management of PSF fleet along the Portuguese mainland coast.
- Phytoplankton community structure in the Goro lagoon analyzed by microscopy and molecular approachesPublication . Fondo, Joyce Rukia; Pezzolesi, Laura; Costantini, Federica; Caputo, Nicolè; Mugnai, FrancescoThis study aimed at investigating the phytoplankton dynamics in a coastal lagoon with complex hydrological dynamics (Sacca di Goro, Northern Adriatic Sea, Italy) highly utilized for shellfish farming, by combining a morphological approach (microscopy) with the innovative eDNA metabarcoding, towards a more informed management of transitional areas. A monthly sampling was carried out between September 2020-2021 in 4 sites. Both the molecular and morphological method resulted valid tools for phytoplankton monitoring. Seasonal variation in phytoplankton abundances and high densities during spring dominated by diatoms (Chaetoceros, Skeletonema, Pseudo-nitzschia, and Cyclotella spp.) were found. Differences in taxa identification between the two methods were observed, as 147 and 158 taxa were reported using the morphological and molecular approach respectively. Although eDNA resulted efficient in detecting cryptic taxa and picophytoplankton that were not morphologically identified, limitations were reported in resolution at species level, in quantification and in identification of some groups (Cyanobacteria and Euglenophyceae), due to the lack of representative sequences in current databases. Potential HAB species were found at low densities (dinoflagellates: Prorocentrum cordatum, Gonyaulax sp., Alexandrium sp., Heterocapsa sp., and diatoms: Pseudo-nitzschia delicatissima and seriata complex) which could be threats to shellfish farm and human health. The study highlights the value of implementing monitoring programs using innovative tools (e.g., eDNA) to analyse the phytoplankton diversity and identify toxic species. Due to the sensitivity of transitional ecosystems, combining different approaches, such as microscopy able to quantify phytoplankton at low taxonomic level and a fast and powerful molecular tool, could be fundamental to assess the composition and ecological function of microalgal communities and facilitate a better conservation strategy in view of climate changes.