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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

Potassium fertilization of bluegill ponds

Viriyatum, Rawee. Boyd, Claude E. January 2009 (has links)
Thesis--Auburn University, 2009. / Abstract. Includes bibliographic references (p.27-29).
22

Network analysis of international aquaculture research and development efforts in Rwanda : tracing the flows of knowledge and technology in a USAID-funded collaborative research support program /

Egna, Hillary S. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 1998. / Typescript (photocopy). Includes bibliographical references (leaves 281-329). Also available online.
23

Pond Management Approaches and Effects on Trophic Dynamics

Sherman, Michael Scott 15 December 2012 (has links)
Mississippi has an abundance of ponds which provides a number of opportunities for anglers. Several enhancement strategies are used to improve fish production in ponds, including fertilizing and supplemental feeding. These strategies may ignore the potential ecological impacts that may unexpectedly arise, such as prolific plant growth. This study consists of two phases; first, a mesocosm experiment investigating fertilizer application rates (mg P/L) in relation to potential sunfish growth, and second, a replicated pond experiment consisting of four treatments to simulate commonly used enhancement strategies. Mesocosm experiment showed a peak of sunfish growth at the 0.6 mg P/L level and served as a high fertilizer threshold level in pond experiment. Ponds were surveyed to assess treatment effects on each trophic level. The costs associated with each pond management strategy were documented. Results from this research help refine management recommendations to maximize results while minimizing costs to landowners and ecosystems.
24

The Ecology of Chlorohydra Viridissima in a Small Perennial Pond

Graham, Elizabeth Coffee 08 1900 (has links)
The purpose of this study is to determine the influence of chemical, physical, and bilogical factors on th seasonal variation in population and on reproduction of Chlorohydra Viridissima (Schulze) in a small pernnial pond.
25

Secondary Production of Dragonflies: Comparing Ecosystem Function of Ponds within an Urban Landscape in North Central Texas

Stallings, Gillian Carol 07 1900 (has links)
The change of land use to include more urban areas is considered one of the main threats to biodiversity worldwide. Urban stormwater retention ponds have been built to collect storm runoff intensified by the increase in impervious surfaces. Although subject to environmental pressures like habitat degradation and pollution, these stormwater retention ponds are diversity hotspots by providing habitat for several aquatic and semi-aquatic species, including dragonflies. Previous research in Denton, Texas, has demonstrated that urban stormwater retention ponds support high taxa richness of adult dragonflies, but not for the aquatic nymphs. The current study builds on what we have seen by focusing on the immature aquatic stage as nymphs using secondary production of dominant dragonfly taxa and community structure to compare ecosystem function in three ponds with differing intensities of land use. Comparing communities and secondary production resulted in specific conductivity, dissolved oxygen, complex vegetation, and abundance explaining the differences between dragonfly communities. Secondary production was dependent on abundance which followed the intensity of urban land use surrounding the pond. This study supports that urban land use does have an effect on the functioning of the ponds and shows the importance of studying the communities over a year to get a clearer picture of what is happening in the ponds.
26

Developing a Stormwater Pond Filter to Capture Phosphorus and Other Pollutants

Houston, Stephanie Chung-Pei-Hua 11 June 2018 (has links)
Excess nutrients, particularly phosphorus (P), significantly contribute to anthropogenic eutrophication, which negatively impacts ecosystems, human health, and the economy. Traditional Best Management Practices (BMPs) such as wet retention ponds prevent eutrophication by acting as a sink for nutrients, but can become a source of pollutants if not properly monitored and maintained. A proposed solution is a standalone, multi-stage filter system that can attach to BMPs with standing water for targeted removal of excess nutrients and with the potential to recycle the filter media. The studies in this dissertation seek to address the feasibility of this solution through the following tasks: 1.) develop a tool that can identify ponds and locations within ponds with high total phosphorus (TP) concentrations, 2.) evaluate filter media that can remove P and can be recycled along with captured P, and 3.) develop a filter system that can remove pollutants in separate stages for the option to recycle certain pollutants. The studies focused primarily on P because the nutrient has the potential to be recycled if captured within the filter. Models developed in the first task showed that TP concentrations in the water were correlated with the pond outlet, pH of the water, and iron concentrations. TP concentrations in the sediment were correlated with the pond's length-to-width ratio and the concentration of aluminum and copper. For the second task, a batch experiment and measurements of physicochemical properties were conducted on four biochars (corn stover pyrolized at 400°C , corn stover pyrolized at 600°C, mixed hardwood, and rice husk). Results indicated that mixed hardwood biochar could sorb dissolved phosphorus (DP) above a solution concentration of 2.9 mg P/L. The properties that could allow this biochar to sorb DP were a smaller negative surface charge, high surface area, smaller concentration of elemental P, and more water-extractable cations. A laboratory-scale test of a three-stage filter system was performed as part of the third task. The filter effectively separated nitrogen and P in different stages, but did not separate lead from P. Median water quality parameters (pH, conductivity, temperature, turbidity, dissolved oxygen, carbon, iron) met U.S. EPA recommended limits, but some parameters violated the recommended limits at a few time points. These studies demonstrate that excessive pollutant concentrations exist in current BMPs, which can benefit from a filter system. The filter system has the potential to collect pollutants separately provided that the correct media mix and configuration is identified such that P can be more completely isolated and water quality parameters are met. / PHD / Excess nutrients, particularly phosphorus (P), cause harmful algae blooms in the nation’s water bodies, which negatively impacts ecosystems, human health, and the economy. Structures such as wet retention ponds detain these nutrients by storing them, but can become a source of pollutants if not properly monitored and maintained. A proposed solution is a standalone, multi-stage filter system that can attach to wet retention ponds for targeted removal of excess nutrients and with the potential to recycle the filter media. The studies in this dissertation seek to address the feasibility of this solution through the following tasks: 1.) develop a tool that can identify ponds and locations within ponds with high total phosphorus (TP) concentrations, 2.) evaluate filter media that can remove dissolved P (DP) and can be recycled along with captured DP, and 3.) develop a filter system that can remove pollutants in separate stages for the option to recycle certain pollutants. The studies focused primarily on P because the nutrient has the potential to be recycled if captured within the filter. Models developed in the first task showed that TP concentrations in the water were correlated with the pond outlet, pH of the water, and iron concentrations. TP concentrations in the sediment were correlated with the pond’s length-to-width ratio and the concentration of aluminum and copper. For the second task, four biochars (corn stover pyrolized at 400°C, corn stover pyrolized at 600°C, mixed hardwood, and rice husk) were tested for their ability to collect DP. Only the mixed hardwood biochar was able to collect DP when the surrounding DP solution was higher than 2.9 mg P/L. A laboratory-scale test of a three-stage filter system was performed as part of the third task. The filter effectively separated nitrogen and P in different stages, but did not separate lead from P. Water quality parameters (pH, conductivity, temperature, turbidity, dissolved oxygen, carbon, iron) generally met U.S. EPA recommended limits, but some parameters violated the recommended limits at a few points in time. These studies demonstrate that excessive pollutant concentrations exist in current wet retention ponds, which can benefit from a filter system. The filter system has the potential to collect pollutants separately provided that the correct media mix and configuration is identified such that P can be more completely isolated and water quality parameters are met.
27

Aquatic macroinvertebrate biodiversity of lowland rural and urban ponds in Leicestershire

Hill, Matthew J. January 2015 (has links)
Ponds are common and abundant features in nearly all landscapes typical of European lowland landscapes yet research on freshwater biodiversity has traditionally focussed on larger waterbodies such as lakes and rivers. This has led to an increased need to understand and quantify the biodiversity associated with pond habitats to better inform the active conservation and management of these small waterbodies. This thesis examines the aquatic macroinvertebrate biodiversity (alpha, beta and gamma) and conservation value of 95 ponds in Leicestershire, UK, across a variety of urban and rural landscape types and at a range of spatial scales. In addition, the relative importance of local (physicochemical and biological) and spatial (connectivity) variables in structuring macroinvertebrate communities within ponds is investigated. At a regional scale, the greatest macroinvertebrate biodiversity and conservation value was recorded within meadow ponds compared to urban, agricultural and forest ponds. Spatially, ponds were highly physically and biologically heterogeneous. Temporally (seasonally), invertebrate communities were most dissimilar in meadow and agricultural ponds but assemblages were similar in urban and forest ponds. In urban landscapes, park ponds supported a greater diversity of invertebrates than other urban or garden ponds and typically had a greater conservation value. Garden ponds were the most taxon poor of those investigated. Perennial floodplain meadow ponds supported a greater biodiversity of invertebrates compared to ephemeral meadow ponds although conservation value was similar. Despite regular inundation from the River Soar, ephemeral ponds supported distinct communities compared to perennial meadow ponds. Aquatic macrophytes supported a higher diversity of taxa than other pond mesohabitats across all landscapes studied. Physicochemical factors were identified to be the dominant influence on macroinvertebrate assemblages although, a combination of local and spatial factors best explained the variation in community composition at a regional scale and for meadow ponds. Spatial factors were not identified to significantly influence urban pond communities. This study highlights the ecological importance and conservation value of ponds in rural and anthropogenically disturbed landscapes. Recognition of the significant contribution of ponds to freshwater biodiversity at regional and landscape scales is important for future conservation of pond habitats and will help focus and direct conservation strategies to where they are needed most.
28

A theoretical and empirical consideration of trophic dynamics in some Kansas farm ponds

Arruda, Joseph A January 2011 (has links)
Digitized by Kansas Correctional Industries
29

Performance of a Wastewater Treatment Pond System with Microfiltration

Martin, Eric Todd 01 December 2012 (has links)
ABSTRACT PERFORMANCE OF A WASTEWATER TREATMENT POND SYSTEM WITH MICROFILTRATION Eric Martin The Woodlands Wastewater Treatment Plant (WWWTP) treats wastewater from the Woodlands housing community near Nipomo, California. The treated effluent is recycled for irrigation of a golf course within the community. The treatment facility consists of three facultative ponds in series followed by a microfiltration system and chlorine disinfection. Microfiltration of wastewater pond effluent is a fairly new, and potentially challenging, application of microfiltration. This thesis describes the operating conditions and behavior of the WWWTP pond system followed by a microfiltration system for the purpose of producing recyclable water fit for reuse under the regulations of Title 22. Water quality data were compiled in two ways. Weekly influent and effluent water quality and flow measurements conducted by the WWWTP operators over the course of three years were studied to show the treatment trends of the treatment plant as a whole. In addition, weekly water quality tests were performed on samples of wastewater influent, effluent, and intermediate stages of treatment for 20 weeks and studied to show treatment performance of each individual pond and the microfiltration system. Pond treatment performance was analyzed based on removal of biochemical oxygen demand (BOD) and total suspended solids (TSS) and accumulation of sludge within the pond system. Microfiltration performance was analyzed in terms of meeting the TSS discharge requirement and the membrane fouling rate. The power consumption of the pond system components and the microfiltration system were estimated. The data show that the WWWTP is producing very high quality discharge. Without microfiltration, five-day carbonaceous soluble BOD (csBOD5) averaged 3.0 mg/L and TSS averaged 42.5 mg/L. BOD5 and TSS removal efficiencies were greater than 90%. Microfilter effluent BOD5 and TSS concentrations averaged 3.0 mg/L and 1.6 mg/L, respectively. Total ammonia nitrogen was reduced to 1.61 mg/L. pH remained between 6.5 and 8.5 with few temporary exceptions. The sludge accumulation was at the high end of the range of typical accumulation rates. However, the measured rate is for the first three years of operation and so likely over-estimates the long-term accumulation rate. Although the treatment performance of the WWWTP is excellent, the power consumed was high.
30

Classification and management of earthen aquaculture ponds, with emphasis on the role of the soil

Bowman, James R. 09 January 1992 (has links)
Soil, water, and climatic classification systems are reviewed as background for the construction of a classification system for earthen aquaculture ponds. The physical and chemical properties of important soil types are also reviewed because of the critical role that the soil plays in earthen pond systems. A pond classification system is constructed using key elements from established climate, water, and soil classification systems, and its use as a management tool is demonstrated. Additional benefits of pond classification are discussed. Functional relationships pertaining to a particular management practice--the application of lime--are examined for seven classes of acid soils. Theoretical and empirical models of pH-percent base saturation relationships are evaluated using data from United States soils. Selected models are partially validated using an independent set of data and incorporated into a lime requirement determination model. A table of lime requirement estimates based on initial soil pH values is calculated for each soil class. Partial validation of the classification system is achieved by ANOVA for the cation exchange capacities of the soils, by fitting the selected pH-percent base saturation models to data from an independent source, and by comparison of the estimated lime requirements with previously published guidelines. Possible reasons for weaknesses in the classification system, the pH-percent base saturation models, or the approach to lime requirement determination are explored, and areas requiring further research are identified. Additional uses and benefits, and further validation and refinement of the classification system are discussed. It is concluded that the proposed classification is a good first approximation that provides a basis for further work. / Graduation date: 1992

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