Tesis sobre el tema "Food webs"
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Compte, Ciurana Jordi. "Food webs of Mediterranean coastal wetlands". Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/7879.
Texto completoIn this PhD, direct and indirect effects of key species were studied in the aquatic community of the Empordà wetlands (Mediterranean coastal wetlands with a simple food web). Different field experiments were carried out using microcosms and mesocosms. To analyze the results, three approaches were used: taxonomic, functional and size-based. Results obtained from the experiments confirm that, in situation with absence of predator and dominance of single zooplanktonic specie (in this case Calanipeda aquaedulcis and Daphnia magna), resource partitioning among different developmental stages of same zooplanktonic specie is a strategy to reduce the intraespecific competence when the resource is limiting. On the other hand, the presence of different top-predators in aquatic community (in this case the jellyfish Odessia maeotica and the Iberian toothcarp Aphanius iberus) triggers a trophic cascade in plankton, however they have different top-down effects according to top-predator.
Vander, Zanden M. Jake. "Trophic position in aquatic food webs". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ55390.pdf.
Texto completoChasnoff, Beth. "Food webs of the Cosumnes River, CA /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Texto completoGudmundson, Sara. "Stabilizing factors in spatially structured food webs". Thesis, Linköping University, Linköping University, Theoretical Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-18657.
Texto completoEcological models have problems showing the positive relationship between diversity and stability found in nature. Theory states that complex food webs have high extinction risks and low stability. However, persistent food webs found in nature are large and complex containing many interconnections between species. There are many possible mechanisms enabling persistent food webs such as; complex interaction patterns, asynchronous fluctuations of species densities, environmental fluctuations and spatial distribution. These factors have not been used in classical models. In this study, coloured environmental 1/f noise and dispersal between subpopulations were incorporated into a diamond shaped food web based on a model by Vasseur and Fox 2007. Contradictions between theoretical and empirical results regarding food webs can be resolved by detailed analyses of models, withholding stabilizing mechanisms. Weak environmental 1/f noise generated an increased coefficient of stability but the stabilizing effect of noise can be questioned because of a decreased mean food web biomass and reduced stabilizing effect when reddened. However, detailed studies of the food web revealed that noise can redistribute density proportions between species, evading lowest species density and thereby increase food web resistance to demographic stochasticity and catastrophes. Noise induced density proportion shifts imply that large population sizes are no insurance towards future increase in environmental variance. Synchrony of species environmental responses and dispersal between subpopulations can both have major influences on stability and extinction risk of smaller food webs indicating that spatial structure could be one of the dominating factors stabilizing complex food webs found in nature.
Teng, Jack 1979. "Structure and energetics in theoretical food webs". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80884.
Texto completoMcQuaid, Christopher Finn. "Complex food webs : the role of parasites". Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648943.
Texto completoRead, Daniel Steven. "Molecular analysis of subterranean detritivore food webs". Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55689/.
Texto completoWootton, Louise Sarah. "Salt-flocculated organic matherial as a food source in estuarine food webs". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27750.
Texto completoScience, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
Drakare, Stina. "The Role of Picophytoplankton in Lake Food Webs". Doctoral thesis, Uppsala University, Limnology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2710.
Texto completoPicophytoplankton were inferior competitors for inorganic phosphorus compared to heterotrophic bacteria. This may be due to the source of energy available for the heterotrophs, while cell-size was of minor importance. However, picophytoplankton were superior to large phytoplankton in the competition for nutrients at low concentrations.
Biomass of picophytoplankton was low in brownwater lakes and high in clearwater lakes, compared to the biomass of heterotrophic bacteria. The results suggest that picophytoplankton are inferior to heterotrophic bacteria in the competition for inorganic nutrients in brownwater lakes, where the production of heterotrophic bacteria is subsidized by humic dissolved organic carbon (DOC)
Relative to large phytoplankton, picophytoplankton were most important in lakes with intermediate water colour, despite the fact that the lowest nutrient concentrations were found in the clearwater lakes. Large phytoplankton in the clearwater lakes may be able to overcome nutrient competition with picophytoplankton by vertical migration.
In conclusion, changes in nutrient content, light availability and concentrations of DOC affect the interactions of heterotrophic bacteria, picophytoplankton and large phytoplankton and are therefore important factors for the structure of the food web in the pelagic zones of lakes.
Picophytoplankton (planktonic algae and cyanobacteria, < 2 µm) constitute an important component of pelagic food webs. They are linked to larger phytoplankton and heterotrophic bacteria through complex interactions including competition, commensalism and predation. In this thesis, field and laboratory studies on the competitive ability of picophytoplankton are reported.
Borrvall, Charlotte. "Biodiversity and Species Extinctions in Model Food Webs". Doctoral thesis, Linköping : Department of Physics, Chemistry and Biology, Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6660.
Texto completoChaneton, Enrique Jose. "Herbivore-mediated plant interactions in grassland food webs". Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314368.
Texto completoWeissbach, Astrid. "The role of allelopathy in microbial food webs". Doctoral thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-11375.
Texto completoLandrum, Jason Paul. "Movement of new nitrogen through oceanic food webs". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28151.
Texto completoCommittee Chair: Joseph Montoya; Committee Member: Ellery Ingall; Committee Member: Emanuele DiLorenzo; Committee Member: Marc Weissburg; Committee Member: Mark Hay.
Eklöf, Anna. "Species extinctions in food webs : local and regional processes". Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-51815.
Texto completoZheng, David W. "Theoretical studies linking soil food webs and ecosystem processes /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5347-X.gif.
Texto completoLamb, Philip. "Resolving the role of jellyfish in marine food webs". Thesis, University of East Anglia, 2018. https://ueaeprints.uea.ac.uk/69971/.
Texto completoNielsen, Jens Munk. "Species interactions and energy transfer in aquatic food webs". Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-123600.
Texto completoAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.
Landström, Emelie. "Resource use by macroinvertebrates within boreal stream food webs". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-105593.
Texto completoSabino, Magali. "Bioaccumulation of trace elements in Seychelles marine food webs". Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS026.
Texto completoFood security, that is guarantying food supply and quality while sustainably managing resources, is closely linked to knowing the biology and ecology of consumed species. In a context of global changes that are threatening seafood safety, it is thus necessary to establish baselines on marine ecosystem functioning, as well as nutrient availability and contamination occurrence in seafood. This is all the more important in Small Island Developing States (SIDS), where populations rely on marine resources for their subsistence, and where capture fisheries resources are the main sources of proteins and micronutrients (i.e. essential trace elements) in local populations’ diet. In spite of the importance of tropical systems in ensuring food security, they remain largely understudied compared to polar and temperate systems. This thesis thus aims to better understand the functioning of tropical marine systems, and to establish a baseline on micronutrient availability and metal(loid) contamination in a wide diversity of capture fisheries resources from the Seychelles (Western Indian Ocean), a tropical SIDS. By investigating trace element concentration patterns at the inter- and intraspecific levels, it was possible to identify intrinsic and extrinsic factors influencing trace element bioaccumulation in tropical capture fisheries resources. We thus highlighted the importance of considering different scales (individual, species, and ecosystem) to better understand essential trace element availability and non-essential trace element occurrence in seafood
Marshall, Melanie M. "Interactive effects of wastewater effluent on stream food webs". Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1563457844184326.
Texto completoHamladji, Yasmina. "Efficiency of diatom and flagellate-based marine food webs". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184613.
Texto completoPersson, Jonas. "Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7811.
Texto completoVenzon, Madelaine. "Food webs on plants the role of a generalist predator /". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/82067.
Texto completoLayton, Astrid C. "Food webs: Realizing biological inspiration for sustainable industrial resource networks". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54307.
Texto completoCross, Adam D. P. "The influence of seabird-derived nutrients on island food-webs". Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/6312/.
Texto completoEriksson, Björn. "Diversity of ecosystems : Variation in network structure among food webs". Thesis, Linköpings universitet, Biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130467.
Texto completoO'Mara, Kaitlyn M. "The Effects of Floods on Estuarine Fisheries and Food Webs". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/391521.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
Guo, Fen. "The Influence of Light and Nutrients on Stream Food Webs". Thesis, Griffith University, 2016. http://hdl.handle.net/10072/366591.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
Takahashi, Daisuke. "Theoretical investigation of the eco-evolutionary dynamics of food webs". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/189654.
Texto completoVivas, Muñoz Jenny Carolina. "Trematodes modulate aquatic food webs by altering host feeding behaviour". Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20592.
Texto completoParasites can influence energy transfer through communities via trophic cascades by inducing alterations on consumer-resource interactions. This study evaluated the role of trematodes on their host’s feeding behaviour at two trophic levels. Four different freshwater snail–trematode systems were used to test whether a general pattern can be detected for the impact of infections on snail periphyton grazing activity. Mass-specific periphyton grazing rates of infected snails were higher, lower, or similar to rates of non-infected conspecifics. The variation across systems may result from differences on how the parasites use the resources of the snail and thus affect its energy budget. Eye parasites can impair their host’s sensory performance with important consequences for the detection of prey, predators and conspecifics. European perch experimentally infected with Tylodelphys clavata were used to evaluate their feeding behaviour under competition with non-infected conspecifics, for two different prey species (Asellus aquaticus and Daphnia magna). The distance at which infected fish attacked both prey species was significantly shorter in comparison to non-infected conspecifics. Additionally, infected fish had more unsuccessful attacks and there was a general tendency that non-infected fish consumed more of the available prey. To evaluate whether fish alter their prey preference as a compensatory mechanism, perch from Lake Müggelsee were sampled and their diet was evaluated using both stomach content and stable isotope analyses. Both methods indicated that with increasing infection intensity fish had a more selective diet, while less intensively infected fish appeared to be generalist feeders. The results from this study confirm that trematodes can play a relevant role within food webs by altering their hosts’ feeding behaviour. Furthermore, in this way trematodes can affect the interaction strengths of their hosts with other species at various trophic levels.
Moriarty, David Joseph Wulstan. "Productivity and trophic role of bacteria in acquatic food webs". Thesis, 1990, 1990. http://hdl.handle.net/2440/38537.
Texto completoMoriarty, David Joseph Wulstan. "Productivity and trophic role of bacteria in acquatic food webs". 1990, 1990. http://hdl.handle.net/2440/38537.
Texto completoFelix, Leonardo Gama. "Nutrient Dynamics and Foods Webs". Laboratório Nacional de Computação Científica, 2010. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=202.
Texto completoUma rede trófica reúne as trocas de matéria e energia que ocorrem entre as espécies e entre o meio biótico e abiótico. Visto que os componentes abióticos formam a fonte de recursos basais, a abordagem deste trabalho consiste na avaliação dos efeitos da entrada de nutrientes alóctones em modelos estratégicos que descrevem a dinâmica de redes e cadeias tróficas, concentrando-se na determinação das características das populações de equilíbrio e das dinâmicas das espécies com diferentes respostas funcionais. Modelos estratégicos que contêm informações acerca do comportamento de populações interativas frente à entrada de nutrientes são uma base importante no delineamento de fenômenos gerais que podem ocorrer dentro da dinâmica de comunidades.
nnah, Marie Hannah Marie. "The effects of assembly method on food webs : integrating population dynamics, evolution and web size". Thesis, University of York, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516620.
Texto completoPtacnik, Robert. "Omnivory in planktonic food webs a study on the impact of mixotrophic flagellates and microzooplankton on food web dynamics and productivity". Kiel Inst. für Meereskunde, 2003. http://e-diss.uni-kiel.de/diss_825/d825.pdf.
Texto completoFink, Patrick. "Food quality and food choice in freshwater gastropods field and laboratory investigations on a key component of littoral food webs". Berlin Logos-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2788034&prov=M&dok_var=1&dok_ext=htm.
Texto completoFink, Patrick. "Food quality and food choice in freshwater gastropods : field and laboratory investigations on a key component of littoral food webs /". Berlin : Logos-Verl, 2006. http://deposit.ddb.de/cgi-bin/dokserv?id=2788034&prov=M&dok_var=1&dok_ext=htm.
Texto completoDrexel, Jan Peter. "Contribution of Nitrogen Fixation to Planktonic Food Webs North of Australia". Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19733.
Texto completoDuffy, Sean. "Persistence in intraguild predation food webs: possible solutions to a paradox". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114273.
Texto completoLes interactions prédateurs-proies se produisant entre les concurrents qui partagent une ressource représentent une configuration réseau alimentaire connu sous le nom de prédation « intraguilde » (IGP). La théorie dicte que l'IGP dans sa configuration la plus basique est instable, avec des critères stricts en matière de coexistence. Cependant les prédations intraguildes sont assez fréquentes dans la nature. Le principal objectif de ma thèse était de montrer comment les modifications des interactions IGP peuvent favoriser la persistance de ce réseau trophique. D'abord, j'ai analysé, de façon théorique, les effets de la commutation des proies par les prédateurs intraguildes sur la coexistence. Je me suis ensuite concentré sur les prédations intraguildes dans un système de mytiliculture. J'ai évalué, de façon empirique, les facteurs pouvant modifier les pressions provenant de la prédation intraguilde et étant exercées par les moules sur le zooplancton (proie intraguilde). Mon modèle IGP qui inclut la commutation des proies a abouti à la coexistence sur une plus grande gamme de paramètres par rapport au modèle de base IGP. Dans mon système de mytiliculture, la structure « âge / stade » ainsi que les déplacements de niches ontogénétiques ont été identifiés comme des facteurs modifiant les interactions IGP et qui empêchent potentiellement le zooplancton (la proie intraguilde) d'être exclu. Cette recherche s'ajoute à la littérature sur les interactions IGP et donne un aperçu sur les mécanismes qui permettent à ces réseaux trophiques de persister.
Layer, Katrin. "Responses of freshwater food webs to spatial and temporal PH gradients". Thesis, Queen Mary, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516661.
Texto completoPeralta, Guadalupe. "Food webs from natural to production forests: composition, phylogeny and functioning". Thesis, University of Canterbury. School of Biological Sciences, 2013. http://hdl.handle.net/10092/8556.
Texto completoHogsden, Kristy Lynn. "Structure and function of food webs in acid mine drainage streams". Thesis, University of Canterbury. School of Biological Sciences, 2013. http://hdl.handle.net/10092/10357.
Texto completoLaws, Jacob. "Conduits of contamination to contemporary food webs of the Norfolk Broads". Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2424.
Texto completoPontius, Ruth Atkins. "The impact of zebra mussels (Dreissena polymorpha) on pelagic food webs". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1400072667.
Texto completoGarvey, James E. "Strong interactions and community structure: Testing predictions for reservoir food webs /". The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487944660931703.
Texto completoBarrett, Nicholas John Barrett. "Effects Of Warming and Increased Sediment Inputs on Pelagic Food Webs". Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501154557516404.
Texto completoZurbrügg, Corinne. "Degradation patterns of transgenetic Bt maize in soil and food webs /". Bern : [s.n.], 2008. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Texto completoMerkley, Steven S. "An Invasive Species Reduces Aquatic Insect Flux to Terrestrial Food Webs". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2806.
Texto completoFigueroa, David. "Food web dynamics : new patterns from southern South America and North Wales UK, and the role of basal species structuring food webs". Thesis, Queen Mary, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582554.
Texto completoPi, Lasternas Sébastien Marie Arthur. "Implications of phytoplankton cell death losses forcarbon flux in Oceanic food-webs". Doctoral thesis, Universitat de les Illes Balears, 2012. http://hdl.handle.net/10803/108002.
Texto completoImportant phytoplankton losses by cell death, independent of grazing are occurring in the ocean. Phytoplankton cells have been described to die upon encountering adverse environmental conditions, and cell death and lysis would result in the release of the carbon incorporated in the photosynthesis by the phytoplankton as dissolved organic carbon (PDOC). The availability of dissolved organic carbon (DOC) is a major constraint for the heterotrophic bacteria, consequently the release by cell mortality of the recently photosynthate carbon is expected to benefit the bacterial community and should be channelled through the microbial food web. All this processes have been poorly documented and the contribution of the phytoplankton cell death to the release of PDOC has not been yet explored in natural communities. The goal of this PhD Thesis is to provide quantitative information on phytoplankton and bacteria cell death in natural communities and to document the fraction of DOC released by phytoplankton (PDOC) under contrasting natural conditions. The exploration of the relationships between the phytoplankton cell mortality, DOC released by phytoplankton (PDOC) and microbial survival would contribute to better understand the path of carbon from photosynthesis to heterotrophic bacteria by cell death processes. Contrasting environmental conditions and communities from different oceanic regions including the Mediterranean Sea, Arctic, Antarctic and Atlantic oceans were studied. Evaluations of the in situ health status of the natural phytoplanktonic communities and bacteria were analyzed by testing the cell membrane permeability; a property that define cell death in cell biology. The total primary production, and the DOC production by phytoplankton were quantified to explore its dynamic with regard to the variability in phytoplankton cell mortality. The bacterial cell survival was also assessed under the same contrasting conditions mediating by the quantification of percentage of living heterotrophic bacteria. The proportion of dead of phytoplankton cells from the diverse phytoplankton populations encountered in the different communities, were related to environmental conditions as water temperature and nutrients availability, and helped to identify their competitive success. Consistent proportions of dead natural phytoplanktonic cells were found during this study that could represent in average about half of the total (40.5 %) phytoplankton abundance. Phytoplankton mortality constitutes a major process implicated in the production of dissolved organic carbon, as the percentage of phytoplankton dead cells explained the 41.4 % of the percentage of released production (PDOC) relative to total primary production. The large production of PDOC observed here, represented in average the half of the total primary production (54.4%) and supported, at the oligotrophic NE Atlantic Ocean, a higher bacterial viability.