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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.
151

Climate change time machine : Adaptation to 30 years of warming in the Baltic Sea

Ermold, Friederike January 2016 (has links)
Earth mean surface temperature has increased by 1 °C since the industrial revolution, and this has already had considerable effects on animal and plant species. Ecological responses to the warming climate – often facilitated via phenotypic plasticity – are ubiquitous. However, even though evolution can occur rapidly there are only few examples of genetic adaptation to climate change. In my thesis, I used a near-natural system to study if and how organisms have adapted to 30 years of warming, and how this has affected competitive species interactions. I investigated Baltic Sea populations of the aquatic snails Galba truncatula and Theodoxus fluviatilis, which had been subjected to cooling water discharge from power plants, resulting in water temperatures 4 to 10 °C higher than in the surrounding sea. G. truncatula had high upper thermal limits and large acclimation potential. This plasticity may have helped the species to survive under the new conditions, allowing evolution through natural selection to take place. I found that the populations of the two thermal origins had diverged in SNP markers associated with warmer temperature, whereas divergence in selectively neutral markers was mainly related to geographical distance. Adaptation occurred from standing genetic variation, emphasizing the importance of genetic diversity and population size in enabling the persistence of populations. Changes in thermal sensitivity of growth and survival were subtle yet significant, and complied with theoretical models of thermal adaptation in ectotherms. At the community level, pre-adaptation to warmer conditions aided the native T. fluviatilis when competing with the alien Potamopyrgus antipodarum. However, interspecific competition limited the snails most in those traits favored under warming, highlighting the challenge of adapting to different selecting forces during global change. The persistence of species and populations under climate change depends on several factors - plasticity allowing for initial survival, evolvability in allowing the genetic changes, and species interactions affecting the new ecological niches. The results of my thesis indicate that persistence under climate change is possible when these factors align, but the relative roles of ecology and plasticity may explain why there are so few observed instances of evolution in response to climate change.
152

External Growth Control of Baltic Sea Cyanobacteria

Zakrisson, Anna January 2015 (has links)
The overall aim of the study was to provide better insights to the ecological role and impact of cyanobacteria in Baltic Sea (BS) bay, coastal and open sea areas. Biomass and heterocyst development of diazotrophic, heterocystous cyanobacteria were monitored over several years simultaneously as physical parameters such as nutrients and temperature. Nitrogen fixation was estimated as well as its transfer in the BS food web. Even after decades of debate there is still controversy whether eutrophication of lakes and estuaries/coastal areas should be managed by reducing phosphorus only or also nitrogen. Central to this debate is whether nitrogen fixation by cyanobacteria can replace shortages of combined nitrogen quickly enough to make phosphorus the limiting nutrient and nitrogen removal pointless or even harmful. Also, it is not clear if available combined nitrogen inhibits heterocystous cyanobacterial nitrogen fixation and if it is used for their growth in situ. A large ecosystem-wide experiment started in Himmerfjärden bay in year 1997, where the N-loadings and release depth from a modern sewage treatment plant (STP), located in the inner part of the bay, were modulated. The STP creates a steep gradient of nutrients and stable nitrogen isotopes, which can be used to study uptake of combined nitrogen, as well as biomass development and primary productivity. A 35-year long data series was used to achieve good insights into phytoplankton development and primary productivity in the Baltic Sea over the last couple of decades. These in vivo long time series, based on monitoring data, in combination with shorter series (2-3 seasons, including measurements of colony stoichiometry and stable isotopes), have resulted in a unique meta-dataset, allowing for high-resolution observations into the role of the cyanobacteria in the Baltic Sea ecosystem. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
153

Parallelization of the HIROMB ocean model

Wilhelmsson, Tomas January 2002 (has links)
No description available.
154

Dynamisk massbalansmodellering av fosfor i Östersjön / Dynamic Mass-balance Modelling of Phosphorus in the Baltic Sea

Karlsson, Malin January 2007 (has links)
<p>During the past few years a vast amount of research has been done to increase the understanding of the complex ecosystem of the Baltic Sea. Modelling and simulations are important tools to increase knowledge of the system. A suitable model must be simple to use and the parameters and variables needed in the model must be easy to access.</p><p>In this paper a dynamical mass-balance model, CoastMab, which is validated for smaller coastal areas, has been used to predict concentrations and transports of phosphorus in three large coastal areas - the Gulf of Finland, the Gulf of Gdansk and the Gulf of Riga. CoastMab uses ordinary differential equations to regulate inflow, outflow and internal flows. To reflect seasonal variations in temperature and different types of flows the model has a temporal resolution of a month. The main purposes of this paper have been to evaluate CoastMab, predict the concentrations and the transports of phosphorus in each coastal area and to analyse how much and why the results differ from empirical data.</p><p>The performed simulations show the importance of a correct calculation of the wave base. This is due to its influence on the division between surface and deep water as well as the division of areas of accumulation and areas of erosion and transport. The retention times of surface and deep water calculated by the model also is of great importance because of their direct influence on the flow of water between the study area and the sea outside the area. This together with the concentration of phosphorus determines the flow of phosphorus in and out of the study area.</p><p>The dynamical mass-balance model is considered to work well in the three studied areas even though the areas are outside the model domain in several respects. Even if the predictions of the phosphorus concentration in the gulf of Riga was less accurate than in the other study areas, the prediction was inside the interval of standard deviation that has been calculated from empirical data. The major flow of phosphorus in the model was in the cross section between the Baltic proper and the modelled coastal area.</p><p>Since the model is easy to use and requires only a small number of obligatory input variables it would be appealing to continue development of the model to handle coastal areas of the same size and larger than the study areas in this paper.</p> / <p>Under senare år har mycket forskning utförts för att öka förståelsen av det komplexa ekosystem Östersjön utgör. Viktiga redskap för att öka förståelsen för systemet är modellering och simulering. För att en modell ska vara lämplig att använda är det viktigt att den inte är för komplicerad och att de parametrar och variabler som används i modellen är lättillgängliga.</p><p>I detta arbete har en dynamisk massbalansmodell, CoastMab, som är validerad för mindre kustområden använts för att modellera fosforkoncentrationer och fosforflöden i tre större kustområden - Finska viken, Gdanskbukten och Rigabukten. CoastMab reglerar genom ordinära differentialekvationer inflöden, utflöden och interna flöden. För att kunna hantera säsongsvariationer i temperatur och olika typer av flöden har modellen en temporär upplösning på en månad. Syftet med arbetet har främst varit att se hur väl CoastMab predikterar fosforkoncentrationen och fosforflöden inom respektive område, samt att analysera hur mycket och varför prediktionerna skiljer sig från empiriska data.</p><p>De simuleringar som utfördes visade att djupet på den teoretiska vågbasen, som modellen beräknar, är av stor betydelse eftersom den i sin tur bestämmer fördelningen yt- och djupvatten samt fördelningen av ackumulationsbottnar och erosions- och transportbottnar. De utbytestider för yt- och djupvatten som modellen beräknar är också av största vikt eftersom de har en direkt inverkan på vattenflödet mellan studerat område och havet utanför, vilket i sin tur tillsammans med fosforkoncentrationen bestämmer fosforflöden in och ut ur det studerade området.</p><p>Den dynamiska massbalansmodellen kan anses fungera väl för samtliga tre studerade områden, trots att de ligger utanför modellens domän i flera avseenden. Även om prediktionen av fosforkoncentrationen i Rigabukten blev sämre än för de två övriga områdena, låg prediktionen inom det intervall för standardavvikelsen som beräknats utifrån empiriska data. De största fosforflödena i modellen förekom för samtliga områden i gränssnittet mellan egentliga Östersjön och det modellerade kustområdet.</p><p>Enkelheten i att använda modellen och det låga antalet obligatoriska drivvariabler gör att den är väl värd att utveckla för att hantera områden av samma eller större storlek än de nu studerade områdena.</p>
155

Salt, water and nutrient fluxes to Himmerfjärden bay

Khalili, Maria January 2007 (has links)
<p>Naturvårdsverket rankar övergödningen som det allvarligaste hotet mot Östersjön. Strategin för att bekämpa övergödningen i Östersjön har varit att reducera antropogena utsläpp av fosfor och kväve från punktkällor och diffusa källor. Många forskare anser att primärproduktionen i egentliga Östersjön huvudsakligen är begränsad av kväve varför Sverige har infört ett ambitiöst och kostsamt program för avancerad kväverening på reningsverk. Andra experter hävdar istället att reducerade kväveutsläpp är meningslösa eller rent av skadliga.</p><p>I ljuset av dessa fundamentalt olika åsikter och de helt motsatta strategier de innebär syftar denna studie till att försöka klargöra vilka åtgärder som borde vidtas för att minska övergödningen genom att undersöka området Himmerfjärden som ofta används som ett exempel på lyckad kväverening. Området har också studerats intensivt sedan 1970-talet.</p><p>Detta arbete har använt en processbaserad dynamisk massbalansmodell för salt för att beräkna vattenutbytestider i Himmerfjärden. Flöden av vatten och näringsämnen till och från fjärden har beräknats och det har visats att bidraget av kväve och fosfor till Himmerfjärden från reningsverket är mycket marginellt jämfört med bidraget från Östersjön.</p><p>Denna studie har också genom att granska litteratur och mätdata från Himmerfjärden visat att det finns goda skäl att ifrågasätta hypotesen om att primärproduktionen i Himmerfjärden skulle vara långsiktigt begränsad av kväve. Resultaten av denna studie kommer att användas i framtida massbalansmodelleringar av fosfor, kväve och cyanobakterier i Himmerfjärden.</p> / <p>The Swedish Environmental Protection Agency has ranked eutrophication as the most severe threat to the Baltic Sea. The strategy to combat the eutrophication in the Baltic has been to reduce antrophogenous emissions of phosphorus and nitrogen from point and diffuse sources. Many scientists argue that the primary production in the Baltic proper is primarily limited by nitrogen which is why Sweden and other countries have implemented an ambitious and expensive program of advanced nitrogen removal in sewage treatment plants. Other experts argue that reduced nitrogen load to the Baltic Sea is either pointless or even harmful.</p><p>In the light of these fundamentally different views and the very opposite management strategies they imply, this study aims to more bring clarity to which measures should be taken to reduce eutrophiction by investigating the area of Himmerfjärden. Himmerfjärden is often used as an example of successful removal of nitrogen and the area has been intensively monitored since the 1970’s.</p><p>This work used a process-based dynamic mass balance model for salt to calculate water retention times in Himmerfjärden. Water and nutrient flows to and from the bay have been calculated. It was shown that the contribution of nutrients to Himmerfjärden from the treatment plant is small compared to the contribution from the Baltic Sea.</p><p>This study showed by reviewing literature on Himmerfjärden that there are good reasons to question the hypothesis of Himmerfjärden being nitrogen limited in the long-run. The findings of this study will be used in future mass balance modelling of phosphorus, nitrogen and cyanobacteria in Himmerfjärden.</p>
156

Advective Sediment Modelling with Lagrangian Trajectories in the Baltic Sea

Kling, Hanna January 2005 (has links)
No description available.
157

Utbildning för hållbar utveckling : En studie av de möjligheter, svårigheter, kunskaper och erfarenheter som präglar utbildning för hållbar utveckling idag

Jordaan, Agneta January 2007 (has links)
<p>In agreement with Agenda 21, Baltic 21 Education and the UN decade for education for sustainable development 2005-2014, Sweden has agreed to reform its educational system in order to support a sustainable development. This thesis aims to examine the implications of education for sustainable development from the perspective of teachers of grade seven to nine by identifying the possibilities, difficulties and knowledge that exists around the concept today. This has been done by combining a literature review and a qualitative case-study, which was conducted through five indepth interviews with teachers. The purpose of these interviews was to identify a few different opinions regarding what sustainable development could imply in the reality of the school and classroom. The most important results derived from this study were: Firstly, that there exist problems in applying education for sustainable development in schools today. The reason for this is a lack of understanding of the need for dealing with sustainable development in schools, as well as a lack of understanding of what education for sustainable development implies for education. The second result of importance was that the teachers who took part in the case-study had knowledge and experiences that could easily be combined with education for sustainable development, but that there is a need for teacher education and training on several levels to increase the possibilities of successfully implementing education for sustainable development in the Swedish school-system.</p> / <p>I enighet med bland annat Agenda 21, Baltic 21 Education och FN:s årtionde för utbildning för hållbar utveckling ska Sverige omorientera sina utbildningssystem så att de stödjer en hållbar utveckling. Denna uppsats syftar till att undersöka vad utbildning för hållbar utveckling innebär för lärare i grundskolans högre årskurser,genom att identifiera och undersöka anknutna möjligheter, svårigheter och erfarenheter. Detta har gjorts utifrån en teoretisk litteraturstudie och en kvalitativ fallstudie. Den teoretiska studien baserades på vetenskaplig litteratur såväl som internationella och nationella styrdokument, överenskommelser och undersökningar et cetera. För fallstudien genomfördes fem djupintervjuer med lärare. Detta syftade till att identifiera några olika åsikter om vad perspektivet utbildning för hållbar utveckling kan innebära i skolans verklighet. De viktigaste resultaten som framkom ur denna studie var att det idag förekommer problem med att tillämpa utbildning för hållbar utveckling i skolvärlden. Detta beror dels på bristfällig förståelse för behovet av hållbar utveckling i skolan, och bristfällig förståelse för innebörden av utbildning för hållbar utveckling. Dessutom framkom att de intervjuade lärarna hade mycket kunskap och erfarenhet som är förenlig med utbildning för hållbar utveckling, men att det kommer att behövas lärarfortbildning och utbildning på olika nivåer för att lyckas integrera perspektivet i skolverksamheten.</p>
158

Phytobenthic communities in the Baltic Sea - seasonal patterns in settlement and succession

Qvarfordt, Susanne January 2006 (has links)
<p>Seasonal changes in reproduction, recruitment, occurrence and growth of marine plant and animal species is a common phenomenon world-wide. This thesis investigates whether such seasonal changes could determine the succession in subtidal phytobenthic communities on free space in the Baltic Sea. My results showed circular seasonal patterns both in the settlement of species and in the annual appearance of communities. The circular seasonal pattern was also observed in the succession. Initial species assemblages were determined by the time space became available for colonisation. Although the succession seemed to be directed towards one site-specific final community structure determined by physical factors, the time of the year when space became available influenced the rate of the succession through species interactions. Rapid growth and timing of settlement and free space occurrence allowed early species to occupy all available space and prevent further colonisation, thereby slowing the succession. My results also showed that both settlement and community structure are influenced by substrate characteristics. Studying community development on vertical artificial structures revealed communities with few species and different composition compared to communities on vertical natural substrates. A field study showed that settlement and community structure changed significantly between 60º and 90º substrate slopes. This thesis shows that some differences in the final community structure are determined already at the settlement stage and that the succession pattern varies depending on when free space occurs. However, small inter-annual and site-specific differences in seasonal settlement periods and site-specific final communities mainly determined by physical factors, suggest that succession patterns are relatively predictable. Seasonal changes seem to cause a spiralling succession towards a final, seasonally undulating, state.</p>
159

The Emergence of the Post-Socialist Welfare State - The Case of the Baltic States : Estonia, Latvia and Lithuania

Aidukaite, Jolanta January 2004 (has links)
<p>This dissertation takes a step towards providing a better understanding of post-socialist welfare state development from a theoretical as well as an empirical perspective. The overall analytical goal of this thesis has been to critically assess the development of social policies in Estonia, Latvia and Lithuania using them as illustrative examples of post-socialist welfare state development in the light of the theories, approaches and typologies that have been developed to study affluent capitalist democracies. The four studies included in this dissertation aspire to a common aim in a number of specific ways.</p><p>The first study tries to place the ideal-typical welfare state models of the Baltic States within the well-known welfare state typologies. At the same time, it provides a rich overview of the main social security institutions in the three countries by comparing them with each other and with the previous structures of the Soviet period. It examines the social insurance institutions of the Baltic States (old-age pensions, unemployment insurance, short-term benefits, sickness, maternity and parental insurance and family benefits) with respect to conditions of eligibility, replacement rates, financing and contributions. The findings of this study indicate that the Latvian social security system can generally be labelled as a mix of the basic security and corporatist models. The Estonian social security system can generally also be characterised as a mix of the basic security and corporatist models, even if there are some weak elements of the targeted model in it. It appears that the institutional changes developing in the social security system of Lithuania have led to a combination of the basic security and targeted models of the welfare state. Nevertheless, as the example of the three Baltic States shows, there is diversity in how these countries solve problems within the field of social policy. In studying the social security schemes in detail, some common features were found that could be attributed to all three countries. Therefore, the critical analysis of the main social security institutions of the Baltic States in this study gave strong supporting evidence in favour of identifying the post-socialist regime type that is already gaining acceptance within comparative welfare state research.</p><p>Study Two compares the system of social maintenance and insurance in the Soviet Union, which was in force in the three Baltic countries before their independence, with the currently existing social security systems. The aim of the essay is to highlight the forces that have influenced the transformation of the social policy from its former highly universal, albeit authoritarian, form, to the less universal, social insurance-based systems of present-day Estonia, Latvia and Lithuania. This study demonstrates that the welfare–economy nexus is not the only important factor in the development of social programs. The results of this analysis revealed that people's attitudes towards distributive justice and the developmental level of civil society also play an important part in shaping social policies. The shift to individualism in people’s mentality and the decline of the labour movement, or, to be more precise, the decline in trade union membership and influence, does nothing to promote the development of social rights in the Baltic countries and hinders the expansion of social policies. The legacy of the past has been another important factor in shaping social programs. It can be concluded that social policy should be studied as if embedded not only in the welfare-economy nexus, but also in the societal, historical and cultural nexus of a given society. </p><p>Study Three discusses the views of the state elites on family policy within a wider theoretical setting covering family policy and social policy in a broader sense and attempts to expand this analytical framework to include other post-socialist countries. The aim of this essay is to explore the various views of the state elites in the Baltics concerning family policy and, in particular, family benefits as one of the possible explanations for the observed policy differences. The qualitative analyses indicate that the Baltic States differ significantly with regard to the motives behind their family policies. Lithuanian decision-makers seek to reduce poverty among families with children and enhance the parents’ responsibility for bringing up their children. Latvian policy-makers act so as to increase the birth rate and create equal opportunities for children from all families. Estonian policy-makers seek to create equal opportunities for all children and the desire to enhance gender equality is more visible in the case of Estonia in comparison with the other two countries. It is strongly arguable that there is a link between the underlying motives and the kinds of family benefits in a given country. This study, thus, indicates how intimately the attitudes of the state bureaucrats, policy-makers, political elite and researchers shape social policy. It confirms that family policy is a product of the prevailing ideology within a country, while the potential influence of globalisation and Europeanisation is detectable too.</p><p> The final essay takes into account the opinions of welfare users and examines the performances of the institutionalised family benefits by relying on the recipients’ opinions regarding these benefits. The opinions of the populations as a whole regarding government efforts to help families are compared with those of the welfare users. Various family benefits are evaluated according to the recipients' satisfaction with those benefits as well as the contemporaneous levels of subjective satisfaction with the welfare programs related to the absolute level of expenditure on each program. The findings of this paper indicate that, in Latvia, people experience a lower level of success regarding state-run family insurance institutions, as compared to those in Lithuania and Estonia. This is deemed to be because the cash benefits for families and children in Latvia are, on average, seen as marginally influencing the overall financial situation of the families concerned. In Lithuania and Estonia, the overwhelming majority think that the family benefit systems improve the financial situation of families. It appears that recipients evaluated universal family benefits as less positive than targeted benefits. Some universal benefits negatively influenced the level of general satisfaction with the family benefits system provided in the countries being researched. This study puts forward a discussion about whether universalism is always more legitimate than targeting. In transitional economies, in which resources are highly constrained, some forms of universal benefits could turn out to be very expensive in relative terms, without being seen as useful or legitimate forms of help to families.</p><p> In sum, by closely examining the different aspects of social policy, this dissertation goes beyond the over-generalisation of Eastern European welfare state development and, instead, takes a more detailed look at what is really going on in these countries through the examples of Lithuania, Latvia and Estonia. In addition, another important contribution made by this study is that it revives ‘western’ theoretical knowledge through ‘eastern’ empirical evidence and provides the opportunity to expand the theoretical framework for post-socialist societies.</p>
160

Forecasting GDP Growth : The Case of The Baltic States

Pilström, Patrick, Pohl, Sebastian January 2009 (has links)
<p>The purpose of this thesis is to identify a general model to forecast GDP growth for the Baltic States, Estonia, Latvia and Lithuania. If the model provides reliable results for these states, then the model should be able to forecast GDP growth for other countries of interest. Forecasts are made by using a reduced vector autoregressive (VAR) model. The VAR models make use of past values of Gross Domestic Product-Inflation-Unemployment as explanatory variables.</p><p>The performed forecasts have provided good results for horizons up to t+8. The forecasts for 2009 (t+12) are in line with those of several other actors. It is reasonable to assume that some of the forecasts for t+16 have reliable results. The Lithuanian forecast show a fall in GDP with 12.51 per cent in 2009 and a GDP growth of 4.23 per cent in 2010. The forecast for Estonia show that the GDP will decrease with 1.49 per cent in 2009 and 12.72 per cent in 2010. Finally the forecast for Latvia show a fall in GDP of 3.1 per cent in 2009 and 18 per cent in 2010. From the findings it is possible to conclude that the model provided reliable estimates of future levels of GDP for the Baltic States and the benchmark countries. This indicates that the model should be applicable on other countries of interest.</p>

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