Spelling suggestions: "subject:"fish"" "subject:"fick""
61 |
Effekter av inkuberingstemperatur på kroppsform och fenstorlek hos juvenil atlantlax (Salmo salar L.) / Effects of incubation temperature on body shape and fin size in juvenile Atlantic salmon (Salmo salar L.)Flytström, Annika January 2017 (has links)
Global warming, a consequence of the ongoing climate change, is expected to increase the mean global temperature by up to 5°C this century. This is predicted to have various impacts on the earth's ecosystems and especially on ectotherms which cannot regulate body temperature by endogenous heat production. There is an intensified interest in investigating the outcomes of climate change and the role of developmental phenotypic plasticity in relation to environmental conditions experienced early in life. Here I compare the body shape and fin size of juvenile Atlantic salmon that had been incubated at two different temperature regimes during embryogenesis. Morphometric methods were used to compare body size through a box-truss network of Euclidean distances and the data were then analyzed using discriminant analysis. Fin size was analyzed by comparing fin area using analysis of covariance with body size as the covariate. The fish incubated in ambient (cold) temperatures differed from the fish incubated in ca. 4°C warmer temperatures by having a deeper body shape and bigger pectoral fin area. There was no significant difference for dorsal fin area. My findings support the notion that Atlantic salmon are morphologically plastic when exposed to different temperature regimes during embryogenesis, but additional studies are needed to determine the ecological consequences of these changes. / Global uppvärmning, en konsekvens av pågående klimatförändringar, förväntas öka den globala medeltemperaturen med upp till 5°C det här århundradet. Det här förväntas ha stor påverkan på jordens ekosystem och speciellt ektotermer som inte kan reglera sin kroppstemperatur genom endogen värmeproduktion. Intresset har intensifierats för att undersöka klimatförändringarnas utfall och rollen som fenotypisk plasticitet har som svar på tidiga miljöförhållanden. Kroppsform och fenstorlek jämfördes hos juvenil atlantlax som inkuberats i två olika temperaturbehandlingar under embryogenesen. Morfometri användes för att undersöka kroppsformen genom ett box-truss nätverk av euklidiska avstånd som sedan analyserades med en diskriminant funktionsanalys. Fenstorleken analyserades genom att mäta fenornas area som sedan användes i en kovariansanalys med kroppsstorlek som kovariat. Fiskarna som inkuberades i normal (kall) temperatur skiljde sig från fiskarna som inkuberats i ca 4°C varmare temperatur genom att ha en djupare kroppsform och större area på bröstfenorna. Det fanns ingen signifikant skillnad mellan ryggfenornas area. Mina resultat stödjer idén att atlantlaxen är morfologiskt plastisk när den utsätts för olika temperaturbehandlingar under embryogenesen, men ytterligare studier behövs för att identifiera de ekologiska konsekvenserna av dessa förändringar.
|
62 |
Phenotypic correlates of spawning migration behaviour for roach (Rutilus rutilus) and ide (Leuciscus idus) in the stream Oknebäcken, Sweden.Lindbladh, Emma, Eriksson, Johanna January 2020 (has links)
Migration occurs among many animal species for the purpose of, among other things, finding food or to reproduce. Spawning migration is a form of migration that occurs among many fish species where they move to another site for reproduction. The movement can be obstructed by migration barriers like road culverts. Barriers to migration pose one of the greatest threats to biodiversity and ecosystem functions in freshwater. They impair the connectivity of watercourses and may prevent fish from improving reproductive success or completing their life histories altogether. There are both benefits and costs with migration, benefits such as increased survival for the adults and offspring, and costs such as increased energy consumption and increased mortality. The costs are often dependent on the morphological traits of the individual, like body shape and size. In this study, the spawning migration of two species of fish of the family Cyprinidae, ide (Leuciscus idus) and roach (Rutilus rutilus) was investigated. Few studies have been made on ide or on roach compared to other cyprinids and salmonids. This study might therefore enhance the overall knowledge of these two species. The overall aims of this project are to study and compare phenotypic correlates of spawning migration behaviour of ide and roach. The field studies were performed in Oknebäcken, Mönsterås (SE632310-152985), Sweden in March and April 2020. To describe the watercourse and define the location and characteristics of different potential migration barriers, a simplified biotope mapping method was used. The fish were caught in a hoop net and then measured, weighted, sexed, and injected with passive integrated transponder using the bevel down method. In order to register in stream movement of fish, reading stations with antennas were placed, at two locations upstream from the marking station and one downstream at the estuary. The sex ratio differed from the expected 1:1 with a majority of females for both species. This might be a result of fluctuations in survival of spawn coupled with different age-at-maturity between sexes. We found that individuals that arrived early to the stream were larger for both study species, as other studies also reported. Also, male ide was both larger and arrived before female ide. There might be an energy cost associated with early arrival to the stream and therefore, larger individuals arrive first. For roach, there was no difference in arrival time between the sexes although female roach were larger. There was no difference in the time spent in the stream between the species. For ide, females stayed for a longer period of time in the stream than males. However, the opposite was true for roach. This may be because male roach might benefit from more fertilization events when staying longer. There might therefore be a trade-off between the energy cost in staying in the stream and the increased fitness advantage in fertilization events. We found no correlation between any of the morphological traits and migration distance. However, since very few individuals were registered at the upstream reading stations, there might be an effect of migration barriers on the spawning migration. The mortality after spawning was higher for roach than for ide. For ide, a larger proportion of females than males died. For roach, individuals that arrived early was classified as alive to a greater extent than those who arrived late. Both similarities and differences between the species were discovered in this study which concludes that even closely related species might differ substantially from each other.
|
63 |
Aquaculture in Sweden: challenges and opportunities : Perspectives on sustainable aquaculture developmentSkyllberg, Josefine January 2022 (has links)
The global population is expected to increase and the greatest challenge for the world’s food-producing sector is to secure food and nutrition through sustainable production methods and reduced waste. Aquaculture is the cultivation of aquatic organisms including fish, molluscs, crustaceans and algae, and has a significant role in providing food and employment as the demand for food is increasing. In this study, conventional open-net pen farming was compared to semi-closed aquaculture systems (S-CCS), as well as the possibility of implementing integrated multi-trophic aquaculture (IMTA) in Sweden. Open-net pens are cost-effective and well-proven methods, but due to environmental impacts, the opportunities are limited. Cultivation in S-CCS reduces the environmental impact by strengthening the barrier between the cultivated organism and the surroundings. Implementing IMTA offers the potential for diversification of aquaculture production and economic yield. Sweden has major potential to develop competitive aquaculture through sustainable technological solutions and by diversifying productivity. / Den globala befolkningen förväntas öka och den största utmaningen för världens livsmedelsproducerande sektor är att säkra tillgången på mat och näring genom hållbara produktionsmetoder och minskat avfall. Vattenbruk är odling av vattenlevande organismer inklusive fisk, blötdjur, kräftdjur och alger, och har en betydande roll för att tillhandahålla mat och sysselsättning när efterfrågan på mat ökar. I denna studie jämfördes konventionell kassodling med semi-slutna vattenbrukssystem (S-CCS), samt möjligheten att implementera integrerat multitrofisk vattenbruk (IMTA) i Sverige. Kassodling är kostnadseffektivt och en välbeprövad metod, men på grund av miljöpåverkan är möjligheterna begränsade. Odling i S-CCS minskar miljöpåverkan genom att stärka barriären mellan den odlade organismen och omgivningen. Implementering av IMTA erbjuder potential för diversifiering av vattenbruksproduktionen och ekonomisk avkastning. Sverige har stor potential att utveckla konkurrenskraftigt vattenbruk genom hållbara tekniska lösningar och genom att diversifiera produktiviteten.
|
64 |
The livelihoods of female seaweed farmers : A study about women's experiences of old and new techniques of seaweed farming on Zanzibar, Tanzania.Vestling, Veronika, Forsberg, Viktoria January 2018 (has links)
Seaweed has been hit hard by climate change around the world. The island of Zanzibar, which is the world’s third biggest exporter of seaweed, is one of the places where seaweed is affected. 80 percent of the seaweed farmers on Zanzibar are women who are directly affected by climate change since they are making a living from seaweed farming. New efforts to tackle the impact of climate change on seaweed has been made on Zanzibar through the SEA PoWer project which is a new technique of growing seaweed and enables twenty-four female seaweed farmers to grow in deep and cooler waters instead of the more traditional way which is in shallow waters. The aim of this study is to, from a livelihood perspective, examine women’s experiences and perceptions of the old versus the new techniques of farming seaweed on Zanzibar, Tanzania. The research questions for this study focus on finding out the women’s experiences and perceptions of the changes in the techniques in relation to opportunities for livelihoods through seaweed farming. Furthermore, this study investigates if women experience conflicts of interest with men regarding the use of ocean space. Semi-structured interviews with eleven women who have used the new technique of growing seaweed were conducted and the results was analyzed in the light of previous research, through the definitions of livelihood and gender, and the theoretical concept of feminist political ecology. The result has shown that all women experienced improvements in their livelihoods through the new technique of seaweed farming. One clear improvement was that there were no negative health effects when using the new technique. The study also found that there are no conflicts of interest between men and women regarding the use of ocean space when using the new technique of seaweed farming. The women had a positive view on the future and had high expectations, they had already noticed positive effects on their livelihoods in form of social, human, physical capital and health.
|
65 |
PCB i Oxundasjön och Rosersbergsviken : Prediktiv modellering av återhämtningsscenarierHållén, Joakim January 2016 (has links)
A regional survey of environmentally harmful substances in fish in autumn 2013 revealed elevated levels of polychlorinated biphenyls (PCBs) in perch from Lake Oxundasjön, north of Upplands Väsby in Stockholm County. Follow-up studies have shown that the quantity of PCBs contained in the lake is unique of its kind in Sweden, and that the area of influence also includes downstream Rosersbergsviken, a bay of Lake Mälaren. The elevated concentrations in fish exceed today's market limits and environmental quality standards for PCBs, as of this, responsible authorities discourage from consumption of fish from Lake Oxundasjön and Rosersbergsviken. The aim has been to use statistical analyses and mass-balance modelling to study the current state of the lake system and how it may evolve in the future under different circumstances. There is a statistically significant correlation between PCB levels in sediment and perch from 21 different sites in the Stockholm-Mälaren region, including Lake Oxundasjön and Rosersbergsviken, this was demonstrated with a linear regression model. With the multivariate analysis method principal component analysis (PCA), it was illustrated how the contaminant levels in fish from Lake Oxundasjön and Rosersbergsviken differed on contaminant levels in fish from other sites. The difference mainly concerned the size and composition of PCBs. Mass-balance modelling of quantities and flows of PCBs in Lake Oxundasjön and Rosersbergsviken was made in the simulation program STELLA®. The modelling indicated that the system currently serves as a secondary distribution source of PCBs to the environment. The recovery of PCB levels is slow in the system, it will take more than 25 years for concentrations in fish to reach today’s market limits and environmental quality standards for PCBs. The model was used to evaluate three different treatment methods for Lake Oxundasjön: dredging, capping and activated carbon treatment. Simulations of these treatments led to a substantial improvement of the PCB situation in Lake Oxundasjön. Moreover, they also had a positive impact on the recovery process in the downstream Rosersbergsviken. Future climate changes, with warmer temperatures and higher run off, led to a slightly faster recovery progress of PCBs in the system.
|
66 |
Miljöanpassningar för restaurering av vattendrag i Sverige - Småskalig vattenkraft : Ska inte den vandrande fisken få lov att vandra? / Environmental adaptations of watercourse restoration in Sweden - Small-scale hydropower : Shouldn't the migrating fish be able to migrate?Andreasson, Sandra, Ohlin, Josefin January 2023 (has links)
Vattenkraftverk utgör vandringshinder för den akvatiska faunan i vattendrag. Den vandrande fisken hindras från att nå sina lekområden vilket har lett till ett minskat bestånd. Omprövningen som ska ske av vattenkraften i Sverige kommer att ställa högre krav på miljöanpassningar och bevarandet av ekologin. Elbristen i Europa har lett till en paus av omprövningen. Pausen möjliggör för att få ytterligare kunskap kring utförandet av restaureringsarbetet innan implementeringen. Studiens syfte var att identifiera vilka utmaningar och möjligheter som finns med restaureringsarbetet av vattenkraft, både ur ett socialt och ekologiskt perspektiv. Metoden utgjordes av ett flertal intervjuer med personer som för studien hade relevant kunskap. Resultatet visar på att det finns möjligheter och utmaningar inom samarbete, finansiering och restaurering. Slutsatsen av studien var att omprövningen är en grund till förbättrat arbete som bidrar med tydligare riktlinjer för samarbete, en miljöfonden som kan finansiera miljöanpassningarna och att restaureringsåtgärder faktiskt kommer implementeras. Utmaningarna som identifierades var konflikten mellan olika intressen, den varierande effektiviteten av en fiskväg och kostsamma miljöanpassningar. En utrivning ger snabba positiva förändringar och kan också därför anses vara den mest effektiva miljöanpassningen. Slutligen, restaurering av vattendrag är värdefullt för den akvatiska faunan. / Hydroelectric power plants constitute migration barriers for the aquatic fauna in watercourses. The migrating fish are prevented from reaching their spawning areas, which has led to a reduced stock of fish. Omprövningen of hydropower in Sweden will place higher demands on environmental adaptations and the preservation of ecology. The electricity shortage in Europe has led to a pause of omprövningen. The pause makes it possible to gain additional knowledge about the execution of the restoration work before the implementation. The purpose of the study was to identify which challenges and opportunities exist with the restaureation of watercourses with hydropower, both from a social and ecological perspective. The method consisted of several interviews with people who had relevant knowledge for the study. The results showed that there are opportunities and challenges with cooperation, financing and restoration. The conclusion was that the omprövning contributes with possibilities such as clearer guidelines for cooperation, the environmental fund that can finance the environmental adaptations and that restoration measures will actually be implemented. The identified challenges were conflicts between different interests, the varying efficiency of a fish passage and financing the expensive adaptations. A removal produces rapid positive change and can therefore be considered the most effective environmental adaptation. Finally, restoration of watercourses is valuable for the aquatic fauna.
|
67 |
Perceptions on marine salmonfarming development inBíldudalur, IcelandSkúladottír, Katrín Helga January 2022 (has links)
Marine salmon farming is a new and fast-growing industry in Iceland after decades of uncertainties within aquaculture development in the country. While growing at a tremendous speed in the last few years, the development has been challenged by different social groups in regard to its socio-economic and environmental effects. Research has shown that there is a lack of knowledge on the perceptions on different stakeholders involved in the farming. This study aims to investigate how different stakeholders perceive the marine salmon farming industry being established in Bíldudalur, in the Westfjords of Iceland, by conducting a case study. Semi structured interviews were carried out with different stakeholders as well as an online survey was distributed to the residents of Bíldudalur, following a focus groupdiscussion. Analysis of the responses demonstrated that current aquaculture regulations have not held up with the expanding industry which has created tension amongst stakeholders. The results show that many worry about the wild salmon stock and that with current regulations, it is hard to predict how much marine farmed salmon will be bred in Iceland, due to weak regulations. Simultaneously, the local community of Bíldudalur has experienced a lot of positive changes in their rural community following the establishment of fish farming in their community. On this basis, further research is needed to compare the findings to other rural communities involved in fish farming in Iceland as well as further research on Iceland´s current changes in regulation and policies and how aquaculture development is promoted in Iceland.
|
68 |
Contested Modernism: Black Artists and the Spaces of American Art, 1925-1950Sledge, David January 2024 (has links)
Historically Black colleges and universities served as primary sites of modernist artmaking. In 1920, however, no HBCU offered an art major or employed full-time fine arts faculty. This dissertation examines that swift transformation, demonstrating it not as a simple evolution, but rather as a contested site of Black thought and protest. I show this not through an institutional history or "timeline" of Black college art departments, but rather in a sustained attention towards Black colleges as nodes within a larger network of publics constituting Black modernism as sites for subjectivity. In doing so, this dissertation examines the conjuncture between two coincident forms: that of modernist art and of the same era's radical modes of racial exclusion. I ask what is at stake in art as lived experience, at a moment in which modernist aesthetics made claims as a means of producing novel ways of inhabiting being human while simultaneous modes of racial formation devalued Blackness within that conceptual category as life. Through this, I track aesthetic production as a relation and set of experiences occurring through specific sites and publics as an asymmetric arena for contestation, with an emphasis on historically Black colleges and universities.
My first chapter, "Organize, Strike, Paint: Making Modern Art at Historically Black Colleges," charts that shift in a set of breaks in art-making at HBCUs, arguing for a student-driven movement away from industrial education towards a modernist visual arts, one embedded within a larger constellation of sites. My second chapter, "Aaron Douglas and a Liberatory History of the Senses," looks closely at Fisk University through the work of painter Aaron Douglas in a set of site-specific murals he made which visualize a long narrative of Black history, art, and labor. I argue that Douglas interrogated in those paintings central questions of visual modernism, placing the radical exclusion of Black subjects in slavery and its afterlives in the Jim Crow era as central to an understanding of modern vision and subjectivity. Through such works, HBCUs stand as necessary sites for theorizing a history of vision and its relation to the "human," as a rejoinder to histories of visual modernism that do not meaningfully account for racialization.
In my final chapter, "Black Study in the White Cube: Racialized Subjectivities and the Museum of Modern Art, ca. 1935," I demonstrate the circulation and exclusions that structured Black audiences and art viewing. I do so through an examination of the Museum of Modern Art’s African Negro Art exhibition, which Black artists engaged with as visitors at MoMA, through mediated forms in print and photography, as well as in circulating satellite shows presented at HBCUs. In doing so, I attend to both the modes of viewership at the museum proper as well as the ways it interacted within a broader network of Black publics. Similarly, I examine the specific content of that MoMA exhibit in its primitivist imagination of an African past, one which might be used as a ground for "modern" white subjects. I track how Black artists confronted that continued legacy of anti-Blackness and addressed the immense dislocations inherent in it. Throughout, I provided sustained attention to artists including Hale Woodruff, Loïs Mailou Jones, Aaron Douglas, John Biggers, Romare Bearden, Norman Lewis, Amaza Lee Meredith, William H. Johnson, Augusta Savage, and Elizabeth Catlett.
|
69 |
Unheard Voices and Unseen Fights: Jews, Segregation, and Higher Education in the South, 1910–1964Soltz, Wendy Fergusson January 2016 (has links)
No description available.
|
Page generated in 0.1029 seconds