Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 82 for “"grazers"”.
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The effect of protozoan grazers on the cycling of polychlorinated biphenyls (PCBs) in marine systems
… bacterial prey and phagotrophic protozoan grazers. Initially, I studied the extent to which a protozoan grazer (Uronema sp. - 10μm ciliate) equilibrated with aqueous PCBs within 2-3 hours. Initial calculations predicted rapid equilibration via passive diffusion. Experimentally, no …
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Effects of Grazers and Elevated Temperature on the Dynamics of a Wastewater Algal Treatment System
… factors. This study examined (1) the effect of grazers on nutrient removal rates and (2) the effect of 1.7 °C increase in temperature on algal biomass. The effect of grazers was assessed outdoors by analyzing dissolved and tissue nutrient concentrations in ATS with and without biological …
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The impact of megaherbivore grazers on grasshopper communities via grassland conversion in a savannah ecosystem
Grasshoppers are sensitive indicators of the state of disturbance of grassland ecosystems. This study examined the grasshopper communities inside a game reserve, comparing those found on frequently grazed areas with communities inside plots that exclude megaherbivores. The vegetation inside the …
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The effect of protozoan grazers on the cycling of polychlorinated biphenyls (PCBs) in marine systems
… bacterial prey and phagotrophic protozoan grazers. Initially, I studied the extent to which a protozoan grazer (Uronema sp.-10[micro]m ciliate) equilibrated with aqueous PCBs within 2-3 hours. Initial calculations predicted rapid equilibration via passive diffusion. Experimentally, no …
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Feeding facilitation, the hidden interaction in mammalian herbivore assemblages?: a case-study on rabbits (Oryctolagus cuniculus L.) and large grazers
This thesis focuses on the positive interaction ‘feeding facilitation’ which is predicted to occur in assemblages of large and small(er) herbivore species. The main hypothesis of the research is that introduced large herbivores facilitate rabbits (medium-sized herbivores) by modification of the …
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Investigation Into Geometry and Behavior of Cislunar GEO-Grazer Orbits
… of cislunar trajectories referred to as GEO-grazers: orbits that traverse the Earth–Moon system while grazing or passing below geosynchronous Earth orbit (GEO). These trajectories are of interest for cislunar space domain awareness (SDA) because they provide natural dynamical pathways by …
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Influence of protozoan grazing on the marine geochemistry of particle reactive trace metals
Planktonic protozoan grazers have the potential to significantly affect the chemistry of particle-associated trace metals. This is due both to the importance of protists as consumers of bacterial-sized particles, and to the unique low-pH, enzyme-rich microenvironment of the grazer food vacuole. …
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Stable isotope analysis of fauna and soils from sites in the Eastern Free State and Western Lesotho, Southern Africa : a palaeoenvironmental interpretation
… the trophic levels, through dietary intake by grazers, and decomposition into soil sediments. By measuring the ¹³C/¹²C ratios of carbon extracted from the calcified tissues of grazers and soil organic matter recovered from within an archaeological context, a palaeoenvironmental sequence has …
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An isotope comparison of elephant (Loxodonta africana) diets in the Kruger National Park and Welgevonden Game Reserve
… is uncertainty as to whether they are primarily grazers or browsers. This has implications for conservation in Africa, as elephants are considered a keystone species in wildlife areas, and are associated with a number of management issues. This dissertation focuses primarily on spatial and …
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The effects of algal density on growth of heterotrophic microflagellates
… in the ocean is generally thought to be as grazers of bacteria, but they may also play an important role as grazers of photoautotrphs. The goal of the present study was to understand the basic growth kinetics of nanoilagellates feeding herbivorously. This was done using batch cultures in …
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Effect of organic nutrient perturbation on microbial community dynamics and composition in Scottish coastal waters
… on the growth of bacteria and their grazers, the effect of DOM produced by nutrient-stressed phytoplankton on the bacterioplankton dynamics or the factors limiting the natural microbial communities. These experiments highlighted the key role of bacteria within the microbial loop, …
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A biologically-active pest deterrent: what is the mode-of-action and how does this affect pest behaviour?
… stakeholders in the United Kingdom and overseas. Grazers Ltd has set out to produce an environmentally sustainable feeding deterring product, which can be applied in a similar fashion as chemical pesticides, but without the harmful side effects. The Grazers Ltd G3 product has a simple formulation, …
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The Influence of Changing Nutrients and Warming on Phytoplankton and its Interactions with Zooplankton in the North Sea
… Bottom-up strength (from primary producers to grazers) is highest under high light availability, N:P between 20 and 25, and intermediate SST; whereas top-down strength (from grazers to primary producers) dominates under lower light availability and N:P below 16. Other network properties respond …
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The ecological effects of grazing by the White Rhino (Ceratotherium simum simum) at a landscape scale
… rainfall mesic savanna. Other smaller species of grazers could not replicate the effect of White Rhino when their grazing was removed. In Umfolozi, a semi-arid savanna, other species of grazer could replace the effect of White Rhino grazing and exert a controlling influence on grass biomass. Hence …
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Effects of frequent burning on grass-grazer interactions in a mesic savanna
… covered with nutritious new regrowth, which grazers move into and utilise as a food resource. The effect of this change in animal grazing patterns on the grass communities is not yet well understood. Certain grass communities depend on heavy, continuous grazing for their persistence: they are …
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Rock hyraxes (Procavia capensis) and their environments : δ13Ccollagen and δ15Ncollagen as environmental indicators
… concluded that rock hyraxes are preferential grazers. There is comparatively little evidence, however, for the dietary preference of South African rock hyraxes, although it has been suggested that they consume more browse. This research aims to quantify the carbon isotopic ratios in their bone …
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Influence of leaf traits, hydrodynamics and global change on seagrass-grazer interactions
… impact on seagrass communities and that their grazers may be key to understand seagrass food webs. Thus, the contrasting response found in previous research may indicate that the susceptibility of seagrass species to be grazed may have a temporal and spatial component and even within a …
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Ecology of acidification and recovery in Welsh upland streams
… assemblages. Acid streams supported fewer grazers and filter-feeders than circumneutral waters but other functional groups were less affected by low pH. Field experiments tested the effects of acidification on two key processes in stream ecosystems, benthic algal grazing and leaf …
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Climate, Ecology, and Human Evolution during the Plio-Pleistocene
… are persistently dominated by C<sub>4</sub>-grazers.</p> <p>The second part of this dissertation is focused on climate and human evolution. The notion that aridity and seasonality have increased over the Pliocene and Pleistocene has remained central to models of environmental change (i.e. …
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Fish Assemblage Structure Before and After a Marine Heatwave in West Hawai'i
… consumers, planktivores, corallivores, scrapers, grazers and browsers. Our study revealed three key findings. First, we show that regardless of habitat differences and management strategy, all fish assemblages became more homogeneous after a major marine heatwave. Second, we found that only eight …
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