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.

This study was designed to integrate a mailing list-based survey with an internetbased presentation/response in order to take into account the trend toward selfadministration that is evident in everyday interactions with automated services that have taken the place of personal interactions. A random sample of 2,999 was taken from applicants for Triploid Grass Carp Permits from the Texas Parks and Wildlife Department. A forty-nine question survey was constructed containing five sections: general pond characteristics, physical pond characteristics, aquatic vegetation, fish and other wildlife, and management goals. The primary emphasis of this study was to determine what specific problems Texas pond owners faced, how widely these problems occurred, and where pond owners got the information they used to deal with pond management problems. A secondary emphasis of the project was to examine the potential presented by the Internet for use in this type of information gathering and distribution for Texas Cooperative Extension. An overall response rate of 21.3% (excluding non-deliverables and unusable submitted surveys) was obtained. Summary statistics for each question were calculated and then compared in order to gain a clearer picture of the pond management practices employed by Texas pond owners. These results indicated some initial discrepancies between pond owners?? management practices and current management recommendations, most dramatically where aquatic vegetation was concerned. The internet-based survey methodology worked effectively to lower the cost of distribution and the workload of data entry when compared to the mail survey. These benefits outweighed the disadvantages caused by survey error with the new methodology.

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.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22760号 / 工博第4759号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 清水 芳久, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The topic of the thesis is determination of concentration of dissolved solids in water and seasonal changes in surface water chemistry for specific affluents of Orlík water reservoir. Water samples were collected on regular basis and analysed in a laboratory during one season (November 2014 - November 2015). The thesis is focused on monitoring of changes in phosphate and nitrate concentrations, in particular. The results of analysis indicate that measured concentrations of substances at monitored locations reflect generally measured data within the region. Concentrations of NO3-N peak in winter to early spring seasons, therefore seasonal changes do occur; differences between locations have not been proven statistically. As for the parameter PO4-P within locations downstream pond systems no significant statistic differences were identified. Values of PO4-P concentration are not primarily associated with agricultural activities but rather with local sources existing within the catch basin. It has been concluded from testing water quality upstream and downstream fish ponds that pond management had no impact on quality of water within the monitored locations in 2015; respectively no additional phosphor and nitrogen load was imposed on Orlík water reservoir