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 54 for “"stream ecosystems"”.
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Factors Influencing the Functional Roles of Crayfish in Stream Ecosystems
… for the majority of crayfish effects in the stream. At Shivering Sands Creek, small crayfish greatly reduced the abundance of many invertebrate taxa and also accelerated leaf litter breakdown rates within enclosures. In times and places where they are abundant, juvenile crayfish may strongly …
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Linking Carbon Dynamics in Stream Ecosystems to Dissolved Organic Matter Quality
Stream ecosystems form an active component of the carbon (C) cycle, and are identified as “hotspots” for carbon dioxide (CO2) emissions. However, the mechanisms driving CO2 emissions from streams are not completely understood. Beside the input of C in the form of CO2 from groundwater, streams …
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Nitrogen spiraling in stream ecosystems spanning a gradient of chronic nitrogen loading
… of nutrient cycling and advective transport) in stream ecosystems. Anthropogenic activities have greatly increased rates of N loading to aquatic ecosystems. However, streams may be important sites for retention, removal, and transformation of N. In order to identify controls on NO3-N spiraling in …
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Effects of Perturbations by Agricultural Land Use on Structure and Function of Stream Ecosystems
The effects of agricultural land use on headwater stream ecosystems were assessed. Three factors were examined: (1) the role of physical and biological processes in terrestrial, riparian, and aquatic portions of agricultural watersheds as regulators of water quality, (2) the changes in fish c
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The influence of land use on the quality of seston in southern Appalachian stream ecosystems
… particles suspended in the water column in stream ecosystems. This detrital pool is a significant vector of energy and nutrients from headwaters to the ocean. Many of the processes involved in seston generation in streams involve the terrestrial ecosystems they drain. My objective was to …
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An analysis of the contamination by and effects of highway- generated heavy metals on roadside stream ecosystems
… effects of these metals on the biota of roadside streams. Sixteen sites located on six small, soft-water streams that were crossed by the highway, encompassing six reference sites located upstream of the highway, six sites located directly at the highway, and four sites located downstream of the …
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Examining the Impacts of Valley Fills in Stream Ecosystems on Amphibian and Aquatic Insect Communities in Southeastern Kentucky
… high abundance and complex life cycles, stream salamanders and aquatic insects are important trophic links and serve a critical role in transferring energy. Despite this importance little research has examined their community structure simultaneously in aquatic ecosystems. The primary …
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Bayesian Methods to Characterize Uncertainty in Predictive Modeling of the Effect of Urbanization on Aquatic Ecosystems
… disrupting the structure and function of stream ecosystems. Urban development introduces contaminants (human waste, pesticides, industrial chemicals). Impervious surfaces and artificial drainage systems speed the delivery of contaminants to streams, while bypassing soil filtration and …
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A study of a Cape mountain stream ecosystem and its response to fire
… of a two-year (1986-1988) study of a mountain stream draining a small catchment in the south-western Cape, South Africa. The catchment was deliberately burnt half-way through the study period. The study was undertaken because although fire is a major natural disturbance, and also a major tool …
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Microbial Communities Colonizing Leaves during Early Decomposition Stages
… an important role in the cycling of nutrients in stream ecosystems. In headwater streams that are deemed as heterotrophic, bacteria and fungi are main drivers of organic matter decomposition and thus partly responsible for facilitating the cycling of nutrients from leaves that fall into the …
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Hydrodynamic controls on the movement of invertebrate larvae and organic matter in small streams
The movement of organisms and resources within ecosystems are essential elements in the productivity, stability, and distribution of communities. This thesis examines how water velocity, a defining factor of lotic systems, influences the dispersion of benthic organisms and particulate organic …
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The Effects of Multiple Stressors on Stream Communities: The Convergence of Drought, Nutrient Pollution, and Invasive Species
… invasive species, have wide-ranging effects on stream population- community- and ecosystem dynamics. We have a broad understanding of how each of these stressors works to influence stream systems independently. However, we still know relatively little about if, and how, these stressors might …
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Microbial and metazoan effects on nutrient dynamics during leaf decomposition in streams
… microbes during leaf decomposition in streams. My research addressed two overarching questions: 1) how do exogenous and endogenous factors interact to drive microbial nitrogen (N) cycling during organic matter decomposition in stream ecosystems, and 2) what affect will the global …
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The effects of forest disturbance on stream stability
… project was designed to examine the stability of stream ecosystems in response to forest disturbance and subsequent succession. Stability was defined as the ability of streams to retain particulate organic matter and nutrients during storms. I hypothesized that forest streams are least stable …
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Thermal Pollution Mitigation in Cold Water Stream Watersheds Using Bioretention
… urban stormwater runoff in developing cold water stream watersheds. Temperature and flow data were collected during ten controlled trials at a bioretention facility located in Blacksburg, Virginia. It was determined that bioretention has the ability to reduce the temperature of thermally charged …
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Effects of physical and chemical disturbance on stream ecosystem structure and function
… influence the structure and function of stream ecosystems. While past investigations have focused on the response of community indicators to stream disturbances, functional indicators may also be helpful for assessing stream ecosystem health. To date, few studies have compared the …
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Influences of Mountainside Residential Development to Nutrient Dynamics in a Stream Network
… and services (e.g., water supply) to downstream ecosystems and human communities. Fast-growing mountainside residential development not only modifies the terrestrial system but also aquatic systems by changing the nutrient input from the terrestrial to aquatic. However, the impacts of …
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Influence of stormwater control measures on watershed hydrology and biogeochemical cycling
… These excess nutrients are ultimately routed to streams through the pipe networks before it can be processed by the vegetation and microorganisms of the landscape. This combination of physical and chemical disturbances impacts stream ecosystems and degrades their ability to perform valuable …
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Modeling Watershed-Wide Bioretention Stormwater Retrofits to Achieve Thermal Pollution Mitigation Goals
Stream ecosystems are increasingly at risk for thermal impairment as urbanization intensifies, resulting in more heated runoff from impervious cover that is less likely to be cooled naturally. While several best management practices, including bioretention filters, have been able to reduce thermal …
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Ecology of acidification and recovery in Welsh upland streams
… structure and function of benthic communities in streams of contrasting pH in mid-Wales, UK, and examines barriers to biological recovery across the sites. The results of field surveys across 30 streams revealed sustained effects of acid stress on macroinvertebrate assemblages. Acid streams …
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