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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.
21

Nordisk odling av tång: Möjligheter och utmaningar : En kvalitativ studie om hur aktörer inom tångbranschen i Norden ser på möjligheter och utmaningar / Nordic farming of kelp: Possibilities and challenges : A qualitative study regarding how actors in the kelp industry in the Nordic countries view possibilities and challenges

Jägenstedt, Nora, Löhning von Matérn, Laura, Pesu Vikström, Frida January 2023 (has links)
Syftet med studien var att undersöka hur aktörer inom tångbranschen i Norden ser på möjligheter och utmaningar i industrin. För att genomföra studien användes kvalitativ metod i form av semistrukturerade intervjuer. Fem personer intervjuades, alla kopplade till tångindustrin i Norden. Intervjuerna syftade till att ge en djupare bild av tångaktörernas syn på möjligheter och utmaningar inom industrin samt deras syn på framtiden. För att analysera det insamlade materialet användes tematisk analys. Den tematiska analysen resulterade i två huvudteman: innovativ framtidssyn och osäker framtid. I resultatet konstaterades det att tångbranschen har potential. Samtidigt visar resultatet att det finns många utmaningar industrin bör hantera innan tång kan etableras i stort på marknaden. Tång anses vara en hållbar råvara som förhoppningsvis kan ersätta vissa landbaserade råvaror, vilket är en av råvarans fördelar. Vidare kan tång växa i samspel med andra marina organismer och även skapa cirkulära samarbeten med landbaserad odling. En av utmaningarna industrin handskas med är höga produktionskostnader; det finns ett behov av teknik som kan driva ner kostnaderna. Det råder även brist på kunskap om råvaran hos konsumenter, vilket leder till svårigheter att marknadsföra samt utöka produktionen. Synen på tång som en hållbar råvara är tvådelad, även om tång som råvara är hållbar i sig, är inte tångodling synonymt med hållbarhet eftersom dess påverkan på marina ekosystem är oviss. Ytterligare en utmaning som industrin brottas med är tångens innehåll av jod. Olika tångarter har olika jodhalt där vissa lämpar sig bättre för mänsklig konsumtion medan andra bör undvikas. Detta i samband med att det finns ett gränsvärde för hur mycket jod som bör konsumeras utgör en av många utmaningar i industrin. / The purpose of the study was to examine how Nordic kelp actors view on possibilities and challenges in the industry. To conduct the study a qualitative method and semistructured interviews were used. Five individuals with connections to the kelp industry in the Nordic countries were interviewed. The interviews aimed to give a more complex picture of the kelp actors view on possibilities and challenges in the industry and their view on the future. To analyze the collected data thematic analysis was applied. The thematic analysis concluded in two themes, innovative view of the future and uncertain future. The result shows that there is potential in the kelp industry, however there are also challenges that needs to be solved before kelp can be established on the market. The potential of the industry is that kelp is seen as a sustainable raw material, and that it potentially could replace some land grown crops. Further can kelp integrate with other marine organisms and have potential to create circular cooperations with land-based cultivation, for example by using it as a fertilizer. One challenge that the industry is facing today is high production costs; there is a need for technology that can lower the costs. The consumers also have a lack of knowledge in the area which leads to producers hesitating to market kelp products sufficiently. The view on kelp as a sustainable raw material is bipartite, even though kelp in itself is sustainable, kelp farming is not equal to sustainability since its impact on the marine ecosystems is uncertain. Another challenge the industry is facing is the iodine content in kelp. Depending on kelp species the iodine content vary, where some of the species are more suitable for human consumption while others should be avoided. This together with the current limit for iodine intake constitutes one of many challenges in the industry.
22

Demography, Biomass Production and Effects of Harvesting Giant Kelp Macrocystis pyrifera (Linnaeus) in Southern New Zealand.

Pirker, John Georg January 2002 (has links)
This study examined the demography of giant kelp Macrocystis pyrifera (Linnaeus) and its interactions with understorey algae and invertebrates in southern New Zealand over two and a half years. Most of the study was done at two sites within Akaroa Harbour (Banks Peninsula) but ancillary sites at Tory Channel (Marlborough Sounds) were used for parts of the study. The kelp forests within Akaroa Harbour were generally highly productive, with a high annual turnover of giant kelp. Macrocystis plants were mostly annual and rarely reached ages greater than 12 months. Peak recruitment occurred in spring (November) during 1995-97, but lesser recruitment episodes occurred throughout the year. The maximum growth rates of Macrocystis fronds were comparable to rates reported elsewhere in southern hemisphere populations (22 mm - 24.5 mmlday), but considerably lower than those in northern hemisphere populations. The major experiment incorporated in the study tested the effects of the Macrocystis canopy and the understorey canopy of the stipitate laminarian Ecklonia radiata on macroalgae and invertebrates. The experiment was structured so that the effects of clearances at different times could be determined. One impetus for this experiment was the need to address issues relating to the commercial harvesting of giant kelp, its sustainability and its effects on other species. The effects of canopy removals on understorey algae, mostly juvenile Macrocystis, Ecklonia and Carpophyllum spp, were highly dependent on the timing of canopy removals and the combinations of canopies removed. For example, winter harvests of the Macrocystis canopy alone enhanced the survival of post-settlement Macrocystis recruits, but had little effect on Ecklonia recruitment. However, when both Macrocystis and Ecklonia canopies were removed in spring, there was heavy recruitment of Ecklonia that grew to dominate the understorey. Strong inter and intraspecific interactions from the Macrocystis surface canopy appeared to have been reduced by physical factors including water turbidity, sedimentation and the deterioration of the surface canopy during summer. These physical factors were not as limiting in Tory Channel. Fine scale extrinsic factor effects including nutrients, light and grazing on the early life history of Macrocystis were investigated in small experiments. Results suggest that recruitment may be nutrient limited even at moderately low temperatures, and that small herbivorous gastropods are an important source of mortality in the early life stages of Macrocystis. Culturing and transplantation cultivation techniques were also examined as a means of supplementing algal supplies. Macrocystis was cultured successfully through its life cycle onto culture ropes, but generally failed to produce visible sporophytes when placed in the field. Cultured plants did grow in Tory Channel, however. Juvenile plants transplanted to ropes for on-farm cultivation showed little growth during summer, but the addition of nutrients significantly enhanced growth rates of these plants during warmer months when natural nutrient levels were low. Increased growth rates at the onset of winter and with the addition of nutrients during summer confirmed that low nutrient levels during summer are growth limiting. Akaroa Harbour kelp forests exhibited considerable variation in Macrocystis canopy biomass through time. For example, the 32,000 m2 kelp forest at Wainui had a biomass of 144 t in October 1995, which then decreased to 21 t in October 1996. Canopies tended to deteriorate during summer. Thus, at Ohinepaka Bay kelp forest had a biomass of 31 t during winter 1997, which decreased to 0.06 t the following summer. The greatest reduction in biomass, however, coincided with a period of hugely increased sediment, which smothered blades in the sea-surface canopy, covered the substratum, and prevented successful recruitment of kelp for over a year. Nutrient depletion was one of several factors thought to cause the summer deterioration of the Macrocystis sea-surface canopy, which has important ramifications for the commercial harvesting of Macrocystis pyrifera in summer. Management considerations and options are discussed in relation the commercial harvesting of Macrocystis in New Zealand. The major conclusion of this study is that although Macrocystis was able to form dense surface canopies during winter its ability to dominate kelp forests was constrained by physical factors, especially sedimentation, high turbidity, nutrients, and storms. The lack of strong interactions between Macrocystis and Ecklonia are also largely a result of their different life history characteristics. Overall, there appear to be no significant negative flow-on effects resulting from kelp harvesting and it appears that Macrocystis can be harvested sustainably.
23

Kelp : Vertikal odling för inomhusmiljö

Rautio, Caroline January 2019 (has links)
Vertikal odling är en växande trend och det är trevligt att ha växter hemma, det ger en känsla av hemtrevnad. Växter bidrar till bättre luftkvalité eftersom de genom fotosyntesen suger i gifter som finns i våran inomhusluft och samtidigt producerar de syre. Växter önskar vatten och ljus för att överleva och för att fotosyntesen ska fungera.   Som designer vill jag ge vertikal odling funktion och formkvalité. Det ska inte bara vara praktiskt utan estetiskt tilltalande. Ett smycke att sätta på väggen.
24

Developing a holonomic iROV as a tool for kelp bed mapping

Williamson, Benjamin January 2013 (has links)
Kelp beds support a vast and diverse ecosystem including marine mammals, fish, invertebrates, other algae and epibiota, yet these kelp beds can be highly ephemeral. Mapping the density and distribution of kelp beds, and assessing change over yearly cycles, are important objectives for coastal oceanography. However, nearshore habitat mapping is challenging, affected by dynamic currents, tides, shallow depths, frequent non-uniform obstacles and often turbid water. Noisy and often incomplete sensor data compound a lack of landmarks available for navigation. The intelligent, position-aware holonomic ROV (iROV) SeaBiscuit was designed specifically for this nearshore habitat mapping application and represents a novel synthesis of techniques and innovative solutions to nearshore habitat mapping. The concept of an iROV combines the benefits of autonomous underwater navigation and mapping while maintaining the flexibility and security of remote high-level control and supervision required for operation in hostile, complex underwater environments. An onboard battery provides an energy buffer for high-powered thrust and security of energy supply. Onboard low-level autonomy provides robust autopilot features, including station-keeping or course-holding in a flow, allowing the operator to direct the survey and supervise mapping data in realtime during acquisition. With the aim of providing high-usability maps on a budget feasible for small-scale field research groups, SeaBiscuit fuses the data from an orthogonal arrangement of a forward-facing multibeam sonar and a complementary 360° scanning sonar with a full navigation suite to explore and map the nearshore environment. Sensor fusion, coupled with the holonomic propulsion system, also allows optimal use of the information available from the limited budget sensor suite. Robust and reliable localisation is achieved even with noisy and incomplete sensor data using a relatively basic Inertial Navigation System and sonar-aided SLAM in the absence of an expensive Doppler velocity log or baseline navigation system. Holonomic motion in the horizontal plane and an axisymmetric hull provide the manoeuvrability required to operate in this complex environment, while allowing 3D maps to be generated in-transit. The navigation algorithms were tested mapping a piling dock and the habitat mapping sensors calibrated using an ‘artificial’ kelp bed of manually dimensioned kelp stipes transplanted to a sheltered but open-water real-world environment. Sea trials demonstrated mapping open ocean kelp beds, identifying clusters of stipes, converting this into a useful measure of biomass and generating a density surface across the kelp bed. This research provides field-proven techniques to improve the nearshore habitat mapping capabilities of underwater vehicles. Future work includes the transition to full-scale kelp bed mapping, and further development of the vehicle and sensor fusion algorithms to improve nearshore navigation.
25

Detrital Production in Kelp Beds

Krumhansl, Kira 28 February 2012 (has links)
Detrital subsidy from highly productive kelp beds and forests to adjacent habitats represents a major form of connectivity between coastal ecosystems that regulates regional patterns of community organization and production. In this thesis, I investigated environmental and biological factors that influence the rate of detrital production in Nova Scotian kelp beds, with emphasis on the role of invasive species in altering these dynamics. The rate of blade erosion of the dominant kelp species (Saccharina latissima and Laminaria digitata) increased significantly with the level of encrustation by the invasive bryozoan Membranipora membranacea and the extent of grazing damage by the native snail Lacuna vincta, and by increased water temperature and site exposure. The rate of detrital production (as dry mass) ranged from 0.5 to 1.71 kg m-2 y-1 across 5 sites, and increased linearly with kelp bed biomass. Spatial variation in the total level of grazing damage on kelp blades by L. vincta was explained in part by a negative relationship with site exposure, and the distribution of grazing along blades was regulated by kelp growth rate and the associated production of grazing-deterrent polyphenolics. Grazing damage by L. vincta that exceeded 0.5 to 1.0% of blade area caused increased rates of erosion during heavy wave action associated with a passing hurricane. The maximum stress before breakage, toughness, and extensibility of blade tissues decreased with the degree of encrustation by M. membranacea or grazing damage by L. vincta, which cause degradation and removal of the outer cell layers of kelp tissues, resulting in stress concentration and breakage at lower force applications than required to break undamaged tissues. The invasive green alga Codium fragile and S. latissima differed with respect to nutritional quality and changes in biochemical composition that occurred over the course of degradation on a sandy bottom adjacent to a kelp bed. Macrofaunal communities colonizing detrital deposits responded to these differences. These findings demonstrate that invasive species can alter the quantity and quality of detritus produced from subtidal kelp beds, and that their community-level effects can extend well beyond the invaded habitats via the export of detritus.
26

Demography, Biomass Production and Effects of Harvesting Giant Kelp Macrocystis pyrifera (Linnaeus) in Southern New Zealand.

Pirker, John Georg January 2002 (has links)
This study examined the demography of giant kelp Macrocystis pyrifera (Linnaeus) and its interactions with understorey algae and invertebrates in southern New Zealand over two and a half years. Most of the study was done at two sites within Akaroa Harbour (Banks Peninsula) but ancillary sites at Tory Channel (Marlborough Sounds) were used for parts of the study. The kelp forests within Akaroa Harbour were generally highly productive, with a high annual turnover of giant kelp. Macrocystis plants were mostly annual and rarely reached ages greater than 12 months. Peak recruitment occurred in spring (November) during 1995-97, but lesser recruitment episodes occurred throughout the year. The maximum growth rates of Macrocystis fronds were comparable to rates reported elsewhere in southern hemisphere populations (22 mm - 24.5 mmlday), but considerably lower than those in northern hemisphere populations. The major experiment incorporated in the study tested the effects of the Macrocystis canopy and the understorey canopy of the stipitate laminarian Ecklonia radiata on macroalgae and invertebrates. The experiment was structured so that the effects of clearances at different times could be determined. One impetus for this experiment was the need to address issues relating to the commercial harvesting of giant kelp, its sustainability and its effects on other species. The effects of canopy removals on understorey algae, mostly juvenile Macrocystis, Ecklonia and Carpophyllum spp, were highly dependent on the timing of canopy removals and the combinations of canopies removed. For example, winter harvests of the Macrocystis canopy alone enhanced the survival of post-settlement Macrocystis recruits, but had little effect on Ecklonia recruitment. However, when both Macrocystis and Ecklonia canopies were removed in spring, there was heavy recruitment of Ecklonia that grew to dominate the understorey. Strong inter and intraspecific interactions from the Macrocystis surface canopy appeared to have been reduced by physical factors including water turbidity, sedimentation and the deterioration of the surface canopy during summer. These physical factors were not as limiting in Tory Channel. Fine scale extrinsic factor effects including nutrients, light and grazing on the early life history of Macrocystis were investigated in small experiments. Results suggest that recruitment may be nutrient limited even at moderately low temperatures, and that small herbivorous gastropods are an important source of mortality in the early life stages of Macrocystis. Culturing and transplantation cultivation techniques were also examined as a means of supplementing algal supplies. Macrocystis was cultured successfully through its life cycle onto culture ropes, but generally failed to produce visible sporophytes when placed in the field. Cultured plants did grow in Tory Channel, however. Juvenile plants transplanted to ropes for on-farm cultivation showed little growth during summer, but the addition of nutrients significantly enhanced growth rates of these plants during warmer months when natural nutrient levels were low. Increased growth rates at the onset of winter and with the addition of nutrients during summer confirmed that low nutrient levels during summer are growth limiting. Akaroa Harbour kelp forests exhibited considerable variation in Macrocystis canopy biomass through time. For example, the 32,000 m2 kelp forest at Wainui had a biomass of 144 t in October 1995, which then decreased to 21 t in October 1996. Canopies tended to deteriorate during summer. Thus, at Ohinepaka Bay kelp forest had a biomass of 31 t during winter 1997, which decreased to 0.06 t the following summer. The greatest reduction in biomass, however, coincided with a period of hugely increased sediment, which smothered blades in the sea-surface canopy, covered the substratum, and prevented successful recruitment of kelp for over a year. Nutrient depletion was one of several factors thought to cause the summer deterioration of the Macrocystis sea-surface canopy, which has important ramifications for the commercial harvesting of Macrocystis pyrifera in summer. Management considerations and options are discussed in relation the commercial harvesting of Macrocystis in New Zealand. The major conclusion of this study is that although Macrocystis was able to form dense surface canopies during winter its ability to dominate kelp forests was constrained by physical factors, especially sedimentation, high turbidity, nutrients, and storms. The lack of strong interactions between Macrocystis and Ecklonia are also largely a result of their different life history characteristics. Overall, there appear to be no significant negative flow-on effects resulting from kelp harvesting and it appears that Macrocystis can be harvested sustainably.
27

Translocation of ¹⁴C in the giant kelps Macrocystis intergrifolia and M. pyrifera

Lobban, Christopher S. January 1976 (has links)
Thesis (Ph. D.)--Simon Fraser University, 1976. / Includes bibliographical references (leaves 85-93).
28

Satellite remote sensing of Nereocystis luetkeana (bull kelp) and the use of kelp by juvenile salmon in the Salish Sea

Schroeder, Sarah 19 December 2019 (has links)
The macro-algae Nereocystis luetkeana or bull kelp is an important canopy-forming species in the rocky nearshore ecosystems of the Salish Sea. It provides structural habitat for many fish and invertebrates including juvenile salmon. In the Pacific Northwest, major declines in Chinook and Coho salmon populations have led to increased scientific efforts to determine the causes behind these losses. High mortality of juvenile salmon during their first months in the marine environment may be linked to loss of habitat such as kelp beds, which can provide shelter, concentration of prey and energetically favorable conditions. This work seeks to understand the role of kelp habitat in the early marine growth period of juvenile salmon. Initially, methods using satellite imagery were developed for mapping the location of kelp beds adjacent to a salmon bearing river in Cowichan Bay, on the West Coast of British Columbia. These methods were then applied to a time series of imagery from 2004 to 2017, to determine how kelp beds are changing over time and the possible drivers of those changes. The results found spatial and temporal variability in kelp beds with a decline from a high in 2015 to the lowest levels in 2017. The observed changes were over a short period considering the natural variability of Nereocystis and continued long term monitoring will help to determine if the declines are permanent. Spatial and temporal variability were found to relate to substrate type, current strengths and potential lag effects of declines due to warmer than average sea surface temperatures. Lastly, the maps created through satellite-based methods served to inform surveys investigating the importance of kelp habitat to the declining populations of Chinook and Coho salmon. To address this, remote underwater video and visual snorkel surveys were used to determine the presence and absence of juvenile salmon in paired kelp and no-kelp sites throughout the season when the fish are known to be present in the region. Higher densities of juvenile salmon were detected in kelp-associated areas; however, this effect was detected both before kelp growth in early spring and during kelp presence. Transects conducted on the inner edge of kelp beds, adjacent to rocky shorelines were determined to have the highest salmon densities indicating that physical factors such as substrate type and wave energy associated with these areas may be preferential to juvenile salmon. / Graduate
29

Recovery of algal assemblages from canopy disturbance : patterns and processes over a range of reef structures /

Toohey, Benjamin D. January 2006 (has links)
Thesis (Ph.D.)--University of Western Australia, 2006.
30

Efeito dos polissacarídeos sulfatados da alga marinha parda Spatoglossum schroederi sobre o aumento da resistência do camarão Litopenaeus vannamei, submetido a situações de estresse / Effect of sulfated polysaccharides from brown seaweed Spatoglossum schroederi on the increased resistance of the shrimp Litopenaeus vannamei, subjected to stress

Lima, Paula Cristina Walger de Camargo January 2007 (has links)
LIMA, Paula Cristina Walger de Camargo. Efeito dos polissacarídeos sulfatados da alga marinha parda Spatoglossum schroederi sobre o aumento da resistência do camarão Litopenaeus vannamei, submetido a situações de estresse. 2007. 84 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Foprtaleza-CE, 2007 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T13:44:29Z No. of bitstreams: 1 2007_dis_pcwclima.pdf: 3778729 bytes, checksum: 45673ef4578b230999ed7a89571f8894 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T13:44:41Z (GMT) No. of bitstreams: 1 2007_dis_pcwclima.pdf: 3778729 bytes, checksum: 45673ef4578b230999ed7a89571f8894 (MD5) / Made available in DSpace on 2016-07-20T13:44:41Z (GMT). No. of bitstreams: 1 2007_dis_pcwclima.pdf: 3778729 bytes, checksum: 45673ef4578b230999ed7a89571f8894 (MD5) Previous issue date: 2007 / O estresse é o agente imunossupressor mais potente na carcinicultura, causando o declínio das defesas naturais dos camarões, deixando-os enfraquecidos e suscetíveis às contaminações por microorganismos patogênicos, presentes na água e nos sedimentos dos viveiros. Sendo assim, o desenvolvimento de estratégias que visem tornar estes animais mais resistentes é de fundamental importância para o sucesso da atividade. Uma possível solução que vem sendo muito estudada nos últimos anos é o uso de compostos imunoestimulantes como, por exemplo, os polissacarídeos sulfatados (PS) de algas marinhas. O presente trabalho avaliou o efeito dos PS extraídos da alga marinha parda Spatoglossum schroederi, no camarão Litopenaeus vannamei, submetidos a condições de estresse. Foram realizados dois ensaios, sendo o primeiro com juvenis e o segundo com pós-larvas (PL’s) do camarão L. vannamei. No primeiro, os PS foram administrados diariamente, através de banhos de imersão, em quatro concentrações, sendo uma controle (nula, 0,0 mg.L-1, 1,0 mg.L-1 e 2,0 mg.L-1), possuindo cada tratamento quatro repetições. A administração das doses foi realizada por 33 dias e o estresse induzido no experimento através da supressão parcial da aeração, durante 5 horas, no 23°, 24° e 25° dia. No segundo ensaio, os PS foram administrados por seis dias, também por banhos de imersão, nas concentrações 0,0 mg.L-1, 2,0 mg.L-1 e 4,0 mg.L-1. As PL’s foram então submetidas ao teste de estresse por choque salino, comumente utilizado nas fazendas de camarão, com quatro repetições para cada tratamento. Após uma semana, o mesmo ensaio foi repetido, visando averiguar o tempo de ação aparente dos polissacarídeos. Os valores médios de sobrevivência foram submetidos à Análise de Variância (ANOVA) e ao teste de Tukey, ao nível de significância de 5%. Em ambos os ensaios, o tratamento 2,0 mg.L-1 apresentou resultados mais efetivos em relação à sobrevivência média, não sendo evidenciado nenhuma relação entre o aumento da sobrevivência e o aumento da dosagem para 4 mg.L-1. Um aparente efeito prolongado do composto também foi detectado uma semana após a administração dos PS. Apesar do aparente efeito imunoestimulante constatado nos ensaios, mais estudos devem ser realizados, buscando otimizar o tempo e método de administração, como também a dose ideal a ser empregada. Deve-se ainda, avaliar a eficiência imunoestimulante do composto através de testes mais específicos utilizando a hemolinfa e o tecido muscular dos animais.

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