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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Ecological Modelling of Lake Ecosystems: Integrating hydro-thermodynamics and biogeochemistry in a reduced complexity framework

López Moreira Mazacotte, Gregorio Alejandro 10 January 2019 (has links)
Freshwater lakes are among the most important ecosystems for both human and other biological communities. They account for about 87% of surface freshwater in the planet, thus constituting a major source of drinking water. They also provide a wide range of ecosystem services that go from the sustenance of a rich biodiversity to the regulation of hydrological extremes; from the provision of a means for recreation to the support of local economies, e.g., through tourism and fisheries, just to cite a few. Lakes are now also widely recognised as natural early warning systems, their responses potentially being effective indicators of local, regional and global scale phenomena such as acidification and climate change, respectively. This is because of their high sensitivity to environmental factors of the most diverse nature that can rapidly alter the course of their evolution. Examples of this are the observed abrupt shifts between alternative stable states in shallow lakes, which led them to become the archetype, go-to example in alternative stable state theory. Therefore, attaining a good scientific understanding of the many processes that take place within these ecosystems is fundamental for their adequate management. Among the tools that serve this purpose, ecological models are particularly powerful ones. Since their introduction in the 1960s, the development of mechanistic ecological models has been driven by their wide spectrum of potential applications. Nevertheless, these models often fall into one of the two following categories: overly simplistic representations of isolated processes, with limited potential to explain real-world observations as they fail to see the bigger picture; or overly complex and over-parameterised models that can hardly improve scientific understanding, their results being too difficult to analyse in terms of fundamental processes and controls. Moreover, it is now well known that an increased complexity in the mechanistic description of ecological processes, does not necessarily improve model accuracy, predictive capability or overall simulation results. To the contrary, a simpler representation allows for the inclusion of more links between model components, feedbacks which are usually overlooked in highly-complex models that partially couple a hydro-thermodynamic module to a biogeochemical one. However, ecological processes are now known to have the potential to significantly alter the physical response of aquatic ecosystems to environmental forcing. For example, steadily increasing concentrations of coloured dissolved organic carbon, a process known as brownification (also browning), as well as the intense phytoplankton blooms that characterise lakes undergoing severe nutrient enrichment, a process known as eutrophication, have been shown to have the potential to alter the duration of the stratified period, thermal structure and mixing regime of some lakes. In this thesis, with the aim of addressing the limitation of partially-coupled models to account for such feedbacks, we further develop a process-based model previously reported in scientific literature. Subsequent studies have already built upon this model in the last few years. In Chapter 2, we do so too by integrating hydro-thermodynamics and biogeochemistry in a reduced complexity framework, i.e., customising the model so that each version only includes the fundamental processes that, brought together, sufficiently describe the studied phenomena. Two case studies served the purpose of testing the adaptability and applicability of the developed model under different configurations and requirements. Limnological data for these two studies were measured at high spatial and temporal resolutions by means of an automated profiling system and recorded as part of two large-scale mesocosm experiments conducted in 2015 and 2016 at the IGB LakeLab in Lake Stechlin, Brandenburg, Germany. Meteorological datasets were also made available to us for both periods by the German Federal Environment Agency. The scope of the first experiment, which we describe in Chapter 3, was that of detecting any changes attributable to eutrophication and browning, in the competition for nutrients and light between four different groups of lake primary producers. These four groups are phytoplankton, periphyton, epiphyton and macrophytes. The model version for this study, therefore, includes equations for all four groups. By tailoring the model to these very specific needs with relative ease, we demonstrate its versatility and hint at its potential. The second experiment, described in Chapter 4, sought to shed light on the largely unknown effects of an increase in the diffuse luminance of the night sky that is due to artificial light at night (artificial skyglow) on lake metabolic rates, i.e., gross primary productivity, ecosystem respiration and net ecosystem productivity (the difference between the first two). For this purpose, an empirical equation for dissolved oxygen concentration was included, the parameters of which were estimated by means of a Markov Chain Monte Carlo sampling method within a Bayesian statistical framework, showing the compatibility, with these statistical methods, of our otherwise fully deterministic model. In Chapter 5, we present a theoretical study on the ecological controls of light and thermal patterns in lake ecosystems. A series of simulations were performed to determine in which cases ecological processes such as eutrophication and brownification may have an observable effect on the physical response of lakes to environmental forcing, which we assessed along a latitudinal gradient. Results show that, in general, across all examined latitudes, and consistent with previous studies, accounting for phytoplankton biomass results in higher surface temperatures during the warm-up phase, slightly lower water temperatures during the cool-down phase, and a shallower thermocline throughout the entire stratified period. This effect is relatively more important in eutrophic lakes where intense blooms are likely. This importance, however, decreases as lakes get browner. Finally, in line with the overall scope of the SMART EMJD, in Chapter 6 we illustrate the case of Ypacaraí Lake, the most important lake in landlocked Paraguay, hoping to provide an example of how interdisciplinary research and international intersectoral collaboration can help bridge the gap between science and management of freshwater ecosystems. This lake presents very special hydro-ecological conditions, such as very high turbidity that can impair phytoplankton growth despite its nutrient-based trophic state indices having consistently fallen within the hyper-eutrophic range in recent years. A strong interest in its complex functioning, through modelling, was taken early on. This led to a collaborative research line being established among several public and private institutions in Italy, Germany and Paraguay. Results so far include: • three concluded UniTN Master theses in Environmental Engineering, partly developed in Paraguay, the first two in collaboration with the “Nuestra Señora de la Asunción” Catholic University (UCNSA) and the third one with the National University of Asunción (UNA); • a collaborative UCNSA-UniTN research proposal submitted for consideration to receive funding through the PROCIENCIA Programme of the National Council of Science and Technology of Paraguay (CONACYT); and • the first multidisciplinary review that has ever been published about the case of Ypacaraí Lake, which highlights the importance of such a collaborative and integrative approach to further advance scientific knowledge and effectively manage this ecosystem.
52

How can light prove to be the urban catalyst to meet targets set out in the Paris Climate Agreement?

Prior, Darran January 2020 (has links)
How can reimagining the way we light our cities prove to be the urban catalyst to meet targets set out in the Paris Climate Agreement? In this Master Thesis, I question how restructuring our urban lighting can provide enormous benefits for not only reducing our energy consumption and becoming more efficient societies, but also support social interaction in shaping our cities for the future. The aspects pertaining to urban lighting and its influence on our environment have been organised into economy, political and urban evolution (social) categories, as a way to dissect and appreciate lights associated role in shaping our societies. Seeking sustainable strategies to meet urgent energy targets and urban development initiatives, are no longer optional but necessary. However, even with this undisputed need for change, particularly within urban lighting, approaches taken are still very much sequestered from general understanding and lack cross-disciplinary cooperation. Extensive publications, works and teachings from lighting designers, as well as currently adopted policies from government bodies and international case studies have been considered, in order to understand current strategies adopted and their potential co-operation for a future holistic strategy in tackling climate change as well as apparent inequalities in our urban environments.
53

In Light of Energy: Influences of Light Pollution on Linked Stream-Riparian Invertebrate Communities

Meyer, Lars Alan 30 August 2012 (has links)
No description available.
54

DEVELOPMENTAL PLASTICITY OF STRESS TOLERANCE AND LIFE-HISTORY STRATEGY TO ARTIFICIAL LIGHT AT NIGHT

Bonfoey, Alyssa M. 01 January 2022 (has links)
Artificial light at night (ALAN), or ecological light pollution, is increasingly prevalent worldwide. Exposure to ALAN tends to negatively impact animals—particularly, nocturnal animals—but life-history strategies may mitigate these costs. Animals in many regions are also increasingly exposed to climate-related stressors, such as heat and drought. Yet, interactions among ALAN, life-history strategy, and stress tolerance are unknown. Therefore, I determined if developmental ALAN exposure (1) affects development, (2) affects adult phenotype, including heat and desiccation tolerance, and (3) affects and/or interacts with life-history strategy. To address my aims, I used the variable field cricket (Gryllus lineaticeps) because its geographic range is increasingly exposed to ALAN, heat, and drought conditions; it exhibits different life-history strategies (flight-capability vs. flight-incapability); and it is mainly nocturnal. Although developmental duration and success were not impacted by ALAN exposure, ALAN affected adult phenotype, with a positive effect on body mass, body size, and reproductive investment, and a negative effect on heat tolerance. Life-history strategy also affected stress tolerance—flight-incapable females had greater heat tolerance, and their desiccation tolerance was improved by ALAN exposure. Thus, key features of environmental change (i.e., exposure to ALAN, heat, and drought) may favor some life-history strategies over others.
55

The impacts of street lighting on bats

Day, Julie January 2017 (has links)
As human population grows and develops, more urban areas are expanding. Urbanisation has many impacts on the natural environment and one understudied pollutant is artificial light at night. The aims of this thesis were to examine the impacts of street lighting on bats and investigate the exposure of British bat species to artificial light at night and explored the mitigation option of part-night lighting. The current exposure of British bat species to artificial lighting was assessed using roost locations and population sizes from a long-term dataset (1997-2012) from the Bat Conservation Trust’s National Bat Monitoring Programme on seven bat species (Eptesicus serotinus, Myotis nattereri, Pipistrellus pipistrellus, P. pygmaeus, Plecotus auritus, Rhinolophus hipposideros and R. ferrumequinum). These data were combined with satellite imagery in roost sustenance zones and home ranges. Bat roosts were found in areas with brighter light levels than random locations for P. pipistrellus, P. pygmaeus and Plecotus auritus. Species that forage around streetlights (P. pipistrellus and P. pygmaeus) had significantly higher light levels in the landscape around their roosts than species which avoid street lit areas (R. hipposideros, M. nattereri and P. auritus). Colony size was negatively correlated with light levels. This study highlights that different species have different requirements in the landscapes around their roosts. To investigate landscapes effects of artificial light at night on the understudied light avoiding species R. ferrumequinum, eight maternity roosts were surveyed to explore the interaction between habitat features and street lighting. At each maternity roost, bat detectors were deployed at 25 paired street lit and dark locations. Street lighting had a significant negative effect on bat activity. Locations closest to the maternity roost had higher bat activity than those further away and road type had a significant effect on bat activity, with the highest bat activity recorded at minor roads compared with A and B roads. These results highlight the large negative impact street lighting can have on bat activity patterns and the need for mitigation. Several mitigation strategies have been suggested to combat the effects of artificial light at night but few have been tested. One of these suggestions is to restrict the hours of lighting through the night, often called part-night lighting. Part-night lighting has been implemented by many local authorities, often switching the lights off after midnight and switching them back on before dusk. To explore the effects of part night lighting on bats, the hourly patterns of activity for R. ferrumequinum were studied. Bat activity was bimodal, with a peak in the first few hours after sunset followed by a smaller peak before sunrise. To capture more than 50% of bat activity during the dark period of the night, street lights would be required to switch off before 11pm. To explore this further, a before-and-after study of part-night lighting was conducted at towns across Devon. Following the conversion from full-night lighting to part-night lighting, switching street lights off at 2 am, there was a significant reduction in P. pipistrellus and a significant increase for P. pygmaeus and Nyctalus noctule activity. Although part-night lighting is not often operational during peak activity periods for bat species, reducing the duration of lighting at night has impacts on activity patterns for several species. This thesis shows that artificial light at night has impacts on bats across the landscapes around their roosts. Artificial lighting has impacts for species in different ways, depending on whether they forage around street lights or avoid street lit areas. For species that avoid street lit areas such as R. ferrumequinum, street lighting can have very significant negative impacts on the availability of areas around their roosts. This highlights the need for conservation measures to reduce impacts of artificial lighting. Although mitigation schemes such as part-night lighting may help to minimize impacts of nighttime lighting, more tailored schemes for bats should devised to achieve greater conservation impacts.
56

People&amp / #8217 / s Experience Of Urban Lighting In Public Space

Unver, Ahmet 01 February 2009 (has links) (PDF)
This thesis aims to create new perspectives in urban lighting design by discovering people&amp / #8217 / s preferences in urban lighting through an exploratory research on people&amp / #8217 / s perceptive experience of urban space at night. In this study, I aim to analyze the common approaches and methods of urban lighting design and make their critique through my research results. Primary research objectives include the evaluation of what people perceive from the urban lighting design and how they feel about the design outcomes. In order to explore people&amp / #8217 / s experience of lit urban space at night, my research comprises a survey that aims to discover people&amp / #8217 / s opinions on certain lit urbanscenes collected from the city of Ankara. Urban lighting design is a discipline that emerged to improve the aesthetic quality of urban space. It has significant effects on people and consequently on urban life. However, in this discipline, exploration of people&amp / #8217 / s needs and preference is a neglected phenomenon. Therefore, this study suggests that it is necessary to review the designer-centered perspective on urban lighting design and question whether existing approach to this discipline has preferable outcomes for people. Through this research I aim to test whether it is appropriate to pursue and carry out the existing type of lighting design, and propose new perspectives to urban lighting.
57

Artificiellt ljus på natten : – en fenomenografisk studie om Sveriges kunskapsläge gällande ljusförorening som miljöproblem / Artificial light at night : – a phenomenographic study of Sweden’s state of knowledge regarding light pollution as an environmental problem

Ljungentorp, Robin January 2021 (has links)
Ljusförorening är ett miljöproblem vilket inbegripes som ett nytt och globalt framväxande fenomen i samband med himlaglim. Miljöproblemet i Sverige erkänns i viss mån med det nuvarande kunskapsläge. Dock saknas det en del kunskap för att komplettera ontologin för att bidra till ökad legitimitet för miljöproblemet bland allmänheten och Sveriges instanser. Studiens teoretiska analysramverket bestod av allmänningens tragedi, biogeoastronomiska natten och legitimitet, som användes till att analysera empirin härlett från studiens intervjumetod. Metoden hade en kvalitativ fenomenografisk ansats som innefattade ett strategiskt urval som var Sveriges instanser. Där uppdagades bristen på opinionsbildning i Riksdagen och Regeringen, trots att det finns motioner som har framlagts som vill att ljusförorening ska uppmärksammas, men att problemet hanteras snarare som en trafikfråga istället för miljöfråga. En del av förklaringen till varför det påverkar samverkan mellan Sveriges instanser för att motverka miljöproblemet. Ljusföroreningar påverkar ekologin och alla dess arter, varav krävs det tydligare riktlinjer för kommuner i deras belysningsplaner gällande att minska deras miljöpåverkan (särskilt för de nattaktiva arter som drabbas) för att nå målet till en mer hållbar belysning; varav ekologiska, ekonomiska och sociala aspekter vävs samman. Varav satsningar att bevara och etablera mörkerreservat är en pusselbit, vilket kan genomföras i samklang med Miljöbalkens författningar. / Light pollution is an environmental problem which is part of a new and globally emerging phenomenon in connection with skyglow. The environmental problem in Sweden is recognized to some extent with the current state of knowledge. However, there is also a lack of knowledge to complete the ontology in order to contribute to increased legitimacy for the environmental problem among the public and within its instances. The study's theoretical analytical framework consisted of the tragedy of the commons, biogeoastronomical night and legitimacy, which were used to analyze the empirical data derived from the study's interview method. The method had a qualitative phenomenographic approach that included a strategic selection of Sweden's instances. Where the lack of opinion formation was discovered in the Parliament and the Government, despite the fact that there is a proposition that has been presented that wants to light pollution to be noticed, but the problem is handled rather as a traffic issue instead of an environmental issue. Part of the explanation for why it affects the collaboration between Sweden's instances to counteract the environmental problem. Light pollution affects the ecology and all its species, which requires clearer guidelines for municipalities in their lighting plans regarding reducing their environmental impact (especially for the nocturnal species affected) in order to achieve the goal of more sustainable lighting; whereof which ecological, economic, and social aspects are woven together. In which investments to preserve and establish the dark sanctuary is a piece of the puzzle, which can be carried out in accordance with the Swedish Environmental Code constitutions.
58

Astro Tourism - A Possible Path to Sustainable Development through Narratives and Stories

Gerasimova, Darina January 2021 (has links)
This thesis focuses on the use of narratives and how they connect Astro tourism to sustainability. This research is done from the viewpoint of the narrators and uncovers what narratives they have chosen to present to the visitors, their reasons to include those narratives, what messages they want to convey and how that relates to sustainability. This research was conducted in order to explore how narratives can be used together with Astro tourism to sustainably develop peripheral regions. This thesis uses a qualitative approach with in-depth interviews and inquests. The informants are people who conduct narrated Astro tourism tours in different parts of the world. The findings of this thesis are that in Astro tourism narratives can be used to educate, inspire, shape perceptions, raise awareness and develop environmental consciousness in people. The narratives can take part in the place, value and identity creation processes, can provide a sustainable competitive advantage, can link together the visual aspects and reconnect the visitors to nature and the past. These findings can be used in the broader field of science about narratives and storytelling in the experience-based industry. On a more practical side it is recommended to include narratives that communicate ideas about sustainability that the narrators personally feel passionate about, and they should consider what kind of message they want to convey through them and how that will affect the customer’s experience.
59

Campus landscape

Dilts, Dustin 09 September 2013 (has links)
This body of work began as an exploration of the University of Manitoba’s Southwood Lands (a former eighteen-hole golf course), with the intention of proposing something new for the site. However, analysis and critical thinking led to the realization that there was a need to not only look at the Southwood Lands, but also the entire Fort Garry Campus. The work evolved through a process of discovery, using a variety of methods from walking the site, documentation through photography, visits to the archives to uncover history, and mapping from afar. One of the underlying objectives was to highlight the importance of taking additional time to understand a place prior to making decisions, revealing what makes a place unique, where the opportunities are, and what has been hidden over time. The idea of a site being a blank slate is dismissed, drawing on the importance of found conditions in decision making. Looking deeper into a place also leads to a greater respect for what is already there. It is what we already have that is so often discarded, and seen as having no value in decision making (the natural areas in a city or the trees on a former golf course for example). It is also the ecosystems that are seen as scrubby and unkept that are the most complex systems and richest spaces for life. Once complex, biologically rich systems are erased there is no going back to them. It is the existing conditions that are worth taking the extra time to investigate, a process that must occur prior to making design decisions that seek to remove or make new. It is only though looking, and looking carefully with un-objective eyes, and an open mind, that design can truly enhance what we already have. This practicum works under the premise that landscape has value in its own right. The landscape is not empty space, not just a place to put buildings, not a luxury that can easily be cut from budgets, and certainly not something that can be considered an afterthought. Instead, landscape is valued as something which is working and active, an essential part of life on this planet that is becoming increasingly important with a rapidly changing climate. The intellectual foundation for organizing ideas around approaching the site have been interpreted from Christophe Girot’s ‘Four Trace Concepts in Landscape Architecture’. They are in this order: landing, grounding, finding, and founding. While Girot’s four trace concepts organize ideas around approaching the site, there are three underlying principles that guide the entire body of work: 1. Landscape as infrastructure and organizing system; 2. Design as a process of discovery; 3. Investigation through multiple scales of inquiry. A strategy for the Fort Garry Campus is where this work concludes, followed by reflections on the importance of context in design and the lessons learned throughout the practicum process.
60

Campus landscape

Dilts, Dustin 09 September 2013 (has links)
This body of work began as an exploration of the University of Manitoba’s Southwood Lands (a former eighteen-hole golf course), with the intention of proposing something new for the site. However, analysis and critical thinking led to the realization that there was a need to not only look at the Southwood Lands, but also the entire Fort Garry Campus. The work evolved through a process of discovery, using a variety of methods from walking the site, documentation through photography, visits to the archives to uncover history, and mapping from afar. One of the underlying objectives was to highlight the importance of taking additional time to understand a place prior to making decisions, revealing what makes a place unique, where the opportunities are, and what has been hidden over time. The idea of a site being a blank slate is dismissed, drawing on the importance of found conditions in decision making. Looking deeper into a place also leads to a greater respect for what is already there. It is what we already have that is so often discarded, and seen as having no value in decision making (the natural areas in a city or the trees on a former golf course for example). It is also the ecosystems that are seen as scrubby and unkept that are the most complex systems and richest spaces for life. Once complex, biologically rich systems are erased there is no going back to them. It is the existing conditions that are worth taking the extra time to investigate, a process that must occur prior to making design decisions that seek to remove or make new. It is only though looking, and looking carefully with un-objective eyes, and an open mind, that design can truly enhance what we already have. This practicum works under the premise that landscape has value in its own right. The landscape is not empty space, not just a place to put buildings, not a luxury that can easily be cut from budgets, and certainly not something that can be considered an afterthought. Instead, landscape is valued as something which is working and active, an essential part of life on this planet that is becoming increasingly important with a rapidly changing climate. The intellectual foundation for organizing ideas around approaching the site have been interpreted from Christophe Girot’s ‘Four Trace Concepts in Landscape Architecture’. They are in this order: landing, grounding, finding, and founding. While Girot’s four trace concepts organize ideas around approaching the site, there are three underlying principles that guide the entire body of work: 1. Landscape as infrastructure and organizing system; 2. Design as a process of discovery; 3. Investigation through multiple scales of inquiry. A strategy for the Fort Garry Campus is where this work concludes, followed by reflections on the importance of context in design and the lessons learned throughout the practicum process.

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