201 research outputs found
Temperature- and light-dependent ratio of energy gain to metabolic costs explains spatial and temporal habitat use of zooplanktivorous fish
No full textUnderstanding the forces that drive habitat selection of species in communities is important in both ecology and evolution. In nature, species face variation in competition, predation and physical characters among habitats. Vendace (Coregonus albula (L.)) is a specialised zooplanktivorous fish predominantly using deeper water in lakes during summer, while roach (Rutilus rutilus (L.)) uses mainly the shallow littoral zone as well as the upper layer of the pelagic zone. To understand mechanisms behind habitat use of these species, I first conducted a predation experiment to investigate their sensitivity to predation by perch (Perca fluviatilis L.). Second, I performed a foraging experiment using different temperature and light treatments. I then used metabolic calculations to estimate energetic costs when foraging. I found no difference between species regarding sensitivity to predation. Vendace was the most efficient forager on zooplankton but also swam faster spending more energy compared to roach. Roach had a comparatively high metabolic rate in the lowest temperature, where their foraging efficiency was lowest. The energy gain ratio at 6°C was highest for vendace, while it was lowest for roach. In the highest temperature (18°C) and the lowest light level (1 lux), both species were similar in their energy gain ratio. The relative energy gain ratio provides a mechanism to explain habitat distribution for the two species. An increased understanding of the role of metabolism in combination with biotic interactions and habitat use may help to foresee effects of environmental change for different species
Habitat selection and indirect interactions in fish ommunities
No full textTo increase the understanding of freshwater lake ecosystems, I have studied the habitat selection of perch (Perca fluviatilis L.), roach (Rutilus rutilus (L.)), and vendace (Coregonus albula (L.)). These fish species use the pelagic and the littoral-benthic habitats in lakes to different extents. Perch and roach are omnivorous, and perch become piscivorous at larger sizes. Vendace is a pelagic species specialized in eating zooplankton. Vendace was expected to affect biotic interactions and habitat use of roach and perch, both directly and indirectly.
I used monitoring data to examine how species distribution patterns, as well as population structures, depended on species composition. In a predation experiment, I studied the relative predation sensitivity as well as evasive behaviours of roach and vendace, with piscivorous perch used as predators. In foraging experiments in aquaria, I studied foraging efficiencies and swimming performances of roach and vendace eating zooplankton in different temperature and light treatments. I then applied metabolic models for roach and vendace, respectively, to compare their net energy gain in different abiotic conditions.
Roach used the pelagic habitat less, and the biomass of roach was lower in lakes with vendace. Results did not support the prediction that perch populations would benefit from the presence of vendace. However, results indicated that a release of competition for small perch may be mediated by vendace, through changed habitat use of roach, increasing the possibilities for predation. Roach and vendace were similar in their sensitivity to predation, indicating that energy gain can explain their habitat use. Foraging efficiencies did not explain the habitat use of roach and vendace in the field. However, the net energy gain in different abiotic conditions, could explain observed patterns of their habitat use in lakes.
This thesis shows how the trade-off between mortality and net energy gain is manifested in habitat use. Including habitat selection in ecological studies may increase our understanding of biotic interactions. Metabolic costs as well as foraging abilities in different abiotic conditions are important for explaining the habitat use of species. Such knowledge can make it possible to forecast how interacting fish species may be affected by environmental change
Habitat use in fish communities
No full textThrough the influence of abiotic factors, the habitat use of organisms affects their metabolism as well as other species- and size-dependent individual-based rates. The habitat-specific performances of individuals interacting in different habitats thereby affect biotic interactions. Habitat use is thus central for the outcomes of biotic interactions that, in turn, regulate populations and communities.
My aim is to investigate how individual processes are influenced by habitat-dependent abiotic factors, affecting biotic interactions to regulate habitat use and population structures in fish communities. I examined patterns of habitat distribution and population structures of perch (Perca fluviatilis L.), roach (Rutilus rutilus (L.)), and the zooplankton specialist vendace (Coregonus albula (L.)) using a database of standardised test fishing data in lakes. To clarify mechanisms, I experimentally studied predation from perch in pond enclosures as well as relative foraging abilities of the two competitors roach and vendace in aquaria with different temperature and light treatments. To test mechanisms in natural situations, I calculated species- and size-dependent net energy intake, incorporating temperature- and light-dependence, including metabolism, using field data from different habitats in lakes with and without vendace. I also developed and applied a stage-structured biomass model, considering a cold water species (vendace) using two habitats differing in temperature. I thereby studied how climate warming which acts differently on different lake habitats affected temperature-dependent individual-based processes, and results on the population level.
Through multi-species studies, I found that a combination of size- and environment-dependent individual processes determining energy gain, rather than predation risk, could explain size- and species-specific habitat use. The single-species study showed that stage-specific intake rates in one habitat, altered by increased temperature, affected intraspecific competition in both habitats, through a mechanism of ‘inter-habitat subsidies’ which altered population structure through maturation and reproduction rates. My thesis shows how including size- and environment-dependent individual processes, and interactions across habitats, increases our understanding of population and community structure as well as effects of environmental change
Corporate Social Responsibility - konstruktionen av dess sociala dimension
No full textAuthor: Ulrika Möllerström Title: Corporate Social Responsibility – the construction of its social dimension. Supervisor: Lars Harrysson Assessor: Carina Tigervall This paper has looked into how the social dimension of the concept “corporate social responsibility” (CSR) is constructed in corporate codes of conduct (CoC) from Swedish clothing companies. Previously made research have shown that no general definition of CSR exists and that the concept revolves around three main dimensions; economic, environmental and social. This paper attempted to, by using social constructivism and discourse theory’s concept of antagonism and hegemony amongst others, uncover the construction of the social dimension of CSR within one separate industry. A discourse analysis of six CoCs, representing ten companies, showed that even though they all share similar or the same main themes, there are crucial differences in how companies choose to write about these themes. For example, all studied CoCs forbid child labor. However, how a child is to be defined and at what age employment is acceptable varies both within CoCs and between them. The concept of CSR’s social dimension can, derived from this paper’s method and result, be understood to be constructed by using themes of a general standard and a specific use of language. This makes every company the constructer of a version of the social dimension, none exactly the same as the other. Key words: corporate social responsibility (CSR), social responsibility, social dimension, code of conduct (COC), discourse, discourse theory, antagonism, hegemony, definition*, construction, Swedish clothing companies
Égalité à la suédoise dans une économie néolibérale
No full textUlrika Jansson analyse le discours néolibéral sur les genres, et le confronte aux orientations politiques devant favoriser l’égalité entre les sexes. En se basant sur des informations collectées auprès de la Confédération des entreprises suédoises, elle montre que les femmes sont considérées à la fois comme ressource économique et problème potentiel sur le marché, pour les mêmes raisons. Les femmes semblent indispensables, pas en elles-mêmes, ni en raison d’une égalité des sexes, mais pour assurer la continuité de l’idéal néolibéral, qui prône la nécessité du marché.Ulrika Jansson analyzes the neoliberal gender discourse in relation to political directives on increasing equal opportunities. The empirical focus is the organization Confederation of Swedish Enterprise. The author shows that women are positioned both as a market economic resource and as a problem for the very same reasons. Women are assumed to be indispensable not in their own right, and not for the sake of gender equality, but in order to ensure that the neoliberal ideal of the necessity of the market can be reproduced
”Ibland är inte målet att bli självförsörjande- utan det kanske är att man ska må bättre.” En kvalitativ studie om aktivering av flyktingar med migrationsrelaterad psykisk ohälsa
No full textAuthor: Ulrika Eklund Title: "Sometimes the goal is not to become self-sufficient, it is rather about feeling better." A qualitative study on the activation of refugees, related to migration and mental illness. Supervisor: Torbjörn Hjort The purpose of this study was to examine how the city of Malmö are working with people with PTSD and mental illness related to migration who receives financial assistance to become self-sufficient. The reason I chose to explore this area was that has shown that migration is associated with mental illness and it takes a long time for refugees and immigrants to establish themselves in the labor market and become self-sufficient. I have limited the study to examine how the professionals in two organizations in Malmö are working with these individuals. The two organizations are the social services of financial assistance and a PTSD- center. The study was made using a qualitative method of doing sex semi-structured interviews. The interviews were conducted with four social worker from different districts and two labor secretaries from a PTSD-center. The collected empirical data was analyzed using the theoretical concepts of structural organization theory, street-level bureaucracies, discretion and collaboration. Results show that the organization affects the professional discretion in working with clients and the social workers had a greater discretion than labor secretaries. I also found that the collaboration between the organizations mostly worked well. As a conclusion I found that the structural conditions and the professionals discretion have an impact on the clients to become self-sufficient
Att besöka någon som inte finns : En intervjustudie om stöd till anhöriga inom demensvården.
No full textAbstract Keywords: elderly people, dementia, person-centered care and relatives. Title: To visit someone who is no longer there Author: Ulrika Stenmarck As the number of elderly people increase, the amount of people suffering from age-related illnesses is growing. Such a disease is dementia, which today is a priority research area, both nationally and internationally. It has been found that working in a person-centered way and involving the patient’s relative’s is important for the people cared for by the dementia departments. Despite this, research has shown that the support for relatives is inadequate. The purpose of this study is to identify how individual support, in the field of nursing for dementia patients, can be better adapted to support relatives. By interviewing five relatives and four staff members in a nursing home for dementia patients, answers were sought for regarding; what kind of support the relatives need and how staff work to support relatives. The relatives´ responses were analyzed based on the theories concerning crisis processing related to their relatives´ dementia diagnoses. The answers given from the staff were analyzed based on the theories concerning organizational culture The analysis indicates that the goal of crisis processing for relatives should be to “create their new life”, which seems to be a challenge for a staff that is already carrying a large workload. The results indicate that the staff have succeeded in creating a foundation of values that relatives seem to experience as a safe atmosphere. This atmosphere can be interpreted as the most important support for relatives and a necessity for progress in their crisis processing. As a complement to the unit’s staff, external support for the families can be a solution
Predicting benthic fauna biomass in the Voordelta under different hypothetical fisheries regimes : Could an expected increase in benthic fauna have occurred within an area protected from demersal trawling if shrimp fisheries should not have increased?
No full textThe aim of this study is to evaluate if an increase in benthic biomass and longer-lived species in the Voordelta area could have been possible if the shrimp fishery would not have increased over the study period. At the instigation of the bottom protection area, there were no signs yet of a very active shrimp fishing fleet, let alone that shrimp fisheries would expand substantially in magnitude. For this reason, the current study evaluates the ‘what-if’ specific changes in the fishery had not happened, how would benthic biomass have developed over time. The study uses the PMR benthic monitoring data and assigns longevity classes to each of the species found in the monitoring data. Cummulative longevity distributions are calculated and a statistical framework is used to estimate how these distributions are affected by fishing, wind and substrate. The resulting statistical model estimates are used in a population model in which we can simulate biomass development per longevity class under a number of fishing scenarios. Five scenarios were evaluated and shown in the figure below, demonstrating that restricting fishing activity by any kind of fleet would have resulted in maximum 5% change in biomass in any particular year. Even if fishing effort would have continued at similar levels as the 2004-2005 baseline situation, including a closure of the bottom protection area in 2008, there would have been a mimimal increase in biomass in the Voordelta area. As demersal fishing has declined more rapidly in recent years than expected (in comparison with the 2004-2005 baseline), there is no marked difference between the expected current state of benthos biomass in the Voordelta and the 04-05 baseline scenario
Habitat selection and indirect interactions in fish communities : mechanisms to explain spatial distribution of perch, roach, and vendace [Elektronisk resurs]
No full textTo increase the understanding of freshwater lake ecosystems, I have studied the habitat selection of perch (Perca fluviatilis L.), roach (Rutilus rutilus (L.)), and vendace (Coregonus albula (L.)). These fish species use the pelagic and the littoral-benthic habitats in lakes to different extents. Perch and roach are omnivorous, and perch become piscivorous at larger sizes. Vendace is a pelagic species specialized in eating zooplankton. Vendace was expected to affect biotic interactions and habitat use of roach and perch, both directly and indirectly. I used monitoring data to examine how species distribution patterns, as well as population structures, depended on species composition. In a predation experiment, I studied the relative predation sensitivity as well as evasive behaviours of roach and vendace, with piscivorous perch used as predators. In foraging experiments in aquaria, I studied foraging efficiencies and swimming performances of roach and vendace eating zooplankton in different temperature and light treatments. I then applied metabolic models for roach and vendace, respectively, to compare their net energy gain in different abiotic conditions. Roach used the pelagic habitat less, and the biomass of roach was lower in lakes with vendace. Results did not support the prediction that perch populations would benefit from the presence of vendace. However, results indicated that a release of competition for small perch may be mediated by vendace, through changed habitat use of roach, increasing the possibilities for predation. Roach and vendace were similar in their sensitivity to predation, indicating that energy gain can explain their habitat use. Foraging efficiencies did not explain the habitat use of roach and vendace in the field. However, the net energy gain in different abiotic conditions, could explain observed patterns of their habitat use in lakes. This thesis shows how the trade-off between mortality and net energy gain is manifested in habitat use. Including habitat selection in ecological studies may increase our understanding of biotic interactions. Metabolic costs as well as foraging abilities in different abiotic conditions are important for explaining the habitat use of species. Such knowledge can make it possible to forecast how interacting fish species may be affected by environmental change
Temperature- and light-dependent ratio of energy gain to metabolic costs explains spatial and temporal habitat use of zooplanktivorous fish [Elektronisk resurs]
No full textUnderstanding the forces that drive habitat selection of species in communities is important in both ecology and evolution. In nature, species face variation in competition, predation and physical characters among habitats. Vendace (Coregonus albula (L.)) is a specialised zooplanktivorous fish predominantly using deeper water in lakes during summer, while roach (Rutilus rutilus (L.)) uses mainly the shallow littoral zone as well as the upper layer of the pelagic zone. To understand mechanisms behind habitat use of these species, I first conducted a predation experiment to investigate their sensitivity to predation by perch (Perca fluviatilis L.). Second, I performed a foraging experiment using different temperature and light treatments. I then used metabolic calculations to estimate energetic costs when foraging. I found no difference between species regarding sensitivity to predation. Vendace was the most efficient forager on zooplankton but also swam faster spending more energy compared to roach. Roach had a comparatively high metabolic rate in the lowest temperature, where their foraging efficiency was lowest. The energy gain ratio at 6 degrees C was highest for vendace, while it was lowest for roach. In the highest temperature (18 degrees C) and the lowest light level (1lux), both species were similar in their energy gain ratio. The relative energy gain ratio provides a mechanism to explain habitat distribution for the two species. An increased understanding of the role of metabolism in combination with biotic interactions and habitat use may help to foresee effects of environmental change for different species
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