京都大学 / 新制・課程博士 / 博士(工学) / 甲第23867号 / 工博第4954号 / 新制||工||1774(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 米田 稔, 准教授 松田 知成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The biomass of the submersed macrophytic vegetation in four hydrilla (Hydrilla verticillata Royle) infested lakes in central Florida was monitored for one year. Lake Orienta and Little Lake Fairview received 2,320 and 960 grass carp, respectively, while Clear Lake and Lake Mann did not receive grass carp. Hydrilla was eliminated in Lake Orienta within six months of stocking; the lake was stocked at 19 grass carp/mt hydrilla (45 fish/ha). Hydrilla was not eliminated from Little Lake Fairview which contained 9 grass carp/mt hydrilla (30 fish/ha). The growth of hydrilla was restricted in Little Lake Fairview which produced 0.380 mt hydrilla, dry organic wt., in contrast to Clear Lake and Lake Mann in which annual net primary production was 0.728 and 0.880 mt organic matter/ha, respectively. The rate of hydrilla growth was greater in the two unstocked lakes. Clear Lake produced 0.31 g/m2/day, dry organic wt., while the net primary productivity of hydrilla in Lake Mann averaged 0.38 g/m2/day. The net primary productivity of hydrilla in Little Lake Fairview was 0.14 g organic matter/m2/day. Three species (in addition to hydrilla) were common to Little Lake Fairview and Lake Mann and provided the only data upon non-target species. Pondweed (Potamogeton illinoensis Morong.) and stonewort (Nitella sp.) were more abundant and more widely distributed in Little Lake Fairview than in Lake Mann. The poor representation of pondweed and stonewort in Lake Mann was attributed to competitive pressure exerted by hydrilla which comprised 83%, by weight, of the annual mean biomass of submersed macrophytic vegetation. In comparison, hydrilla comprised 74% of the annual mean biomass in Little Lake Fairview. The effect of the grass carp in Little Lake Fairview may have been to ease the competitive pressure exerted by hydrilla, allowing pondweed and stonewort to remain well established. The percentage frequency of occurrence was concluded to be a poor criterion for measuring changes in the hydrilla population. Changes in biomass as great as 900% resulted in no change in the percentage frequency of occurrence of hydrilla in Lake Mann.

Benthic macroinvertebrates and physicochemical parameters were monitored simultaneously with hydrilla in a central Florida lake. Changes in the benthos were described in relation to plant growth. Twenty-seven of the 54 taxa of benthic macroinvertebrates collected were members of the Family Chironomidae. Chironomids and oligochaetes numerically dominated the benthos, comprising of 82% of the individual collected. The greatest numbers of species and individuals were found during the winter when hydrilla biomass was low. Hydrilla biomass ranged from 0.385 kg/m2 in April, 1977 to 2.275 kg/m2 in October, 1977. Low numbers of species and individuals were collected from bottom sediments during summer and fall. Dissolved oxygen concentrations at the bottom were approximately 2.0 ppm during summer and fall and possibly limited benthic organisms. The annual means for the Shannon and Simpson Indices for the benthos were 1.92 and 0.36, respectively.

No description available.

Environmental heterogeneity in both space and time has significant repercussions for community structure and ecosystem processes. Dimictic lakes provide examples of vertically structured ecosystems that oscillate between stable and mixed thermal layers on a seasonal basis. Vertical patterns in abiotic conditions vary during both states, but with differing degrees of variation. For example, during summer thermal stratification there is high spatial heterogeneity in temperature, nutrients, dissolved oxygen and photosynthetically active radiation. The breakdown of stratification and subsequent mixing of the water column in fall greatly reduces the stability of the water column to a vertical gradient in light. Nutrients and biomass that were otherwise constrained to the depths are also suspended, leading to a boom in productivity. Freshwater lakes are teeming with microbial diversity that responds to the dynamic environment in a seemingly predictable manner. Although such patterns have been well studied for nanoplanktonic phototrophic and heterotrophic populations, less work has been done to integrate the influence of mixotrophic nutrition to the protistan assemblage. Phagotrophy by phytoplankton increases the complexity of nutrient and energy flow due to their dual functioning as producers and consumers. The role of mixotrophs in freshwater planktonic communities also varies depending on the relative balance between taxon-specific utilization of carbon and energy sources that ranges widely between phototrophy and heterotrophy. Therefore, the role of mixotrophy in the microbial food web is difficult to predict because functional types of mixotrophs along a gradient of nutritional strategies contribute differently to nutrient cycling and carbon sequestration. The overall objective of this work was to advance existing knowledge of the abundance and activity of phagotrophy phytoplankton in lacustrine systems. The incorporation of mixotrophy into the microbial food web requires the complement of physiological studies in culture (as described in chapter 2) and quantification of activity (including abundance and bacterivory) in relation to strict phototrophs and heterotrophs in situ (as described in chapter 3 and 4). Information on the physiological ecology of mixotrophic protists is crucial to understanding their role in planktonic food webs and influence on the dynamic microbial community structure in lake ecosystems. An understanding of the ecological functioning of lakes has ultimate consequences for management of water resources, particularly in the face of global climate change. / Biology

The Moose River Basin in northern Ontario is an important large river system, however very little is known about its aquatic invertebrate community. As macro invertebrates are an integral part of river ecosystems, I conducted an initial assessment of the aquatic invertebrate community structure in the Moose River Basin, at both a fine, and a basin-wide, scale. The fine scale study used invertebrate data collected at five reaches within a 30km stretch of the Groundhog River. The examination of the invertebrate community at a basin-wide scale was accomplished using meta-analysis techniques on twenty-two studies conducted on various rivers within the Basin. The effect of the following factors on community structure were examined: i) the use of different sampling devices, ii) water depth, iii) substrate type, iv) sampling in two consecutive years, and v) spatial scale. I found that the use of various sampling devices resulted in significantly different estimates of community structure. This strongly suggests that consistent sampling protocols are necessary to effectively compare results within, and among, studies. The effect of water depth on community structure was inconclusive, as too few samples were collected to overcome the confounding effects of substrate type. Substrate type had a significant effect on community structure, with greater invertebrate richness and diversity found in fine substrate in the Groundhog River study, but with no consistent patterns at the basin-wide scale. Invertebrate richness and diversity did not differ significantly in the Groundhog River between two consecutive years. In both the fine-scale and the basin-wide studies, the distribution of aquatic invertebrates varied among sites within a river reach, and among reaches within a river. To further examine the biological and physical processes affecting community structure at the fine-scale, consistent sampling protocols should be employed, which may also allow basin-wide trends to emerge. / Thesis / Master of Science (MS)

Due to perceived shortcomings in some aspects of hazard assessment for chemicals administered to aquatic systems, experiments were conducted to determine the effects of copper on various ecological parameters in artificial streams and microcosms. Effects investigated were colonization and growth of periphyton communities in artificial streams, community composition and nutritional content of periphyton in these streams, leaf conditioning and nutritional content in laboratory microcosms, and nutritional suitability of these leaves to a shredding macroinvertebrate. Main effects observed in periphyton growth experiments were significant reduction in substrate colonization due to copper treatment, which led to significantly lower standing biomass in treated streams. Observed growth rates were generally similar between control streams and copper treated streams. Light treatments did not affect periphyton responses to copper. Community composition of the periphyton was affected by 2.5 μg/L copper. Periphyton phosphorus and nitrogen contents were not affected by copper treatment. Conditioning rate of leaves was significantly decreased by 50 μg/L copper treatments in some cases. Leaf phosphate and nitrogen contents were not significantly affected by copper treatment. Significant differences in nutritional suitability of copper-treated leaves to a shredding macroinvertebrate were not detected. These experiments suggest that aquatic primary producers are more sensitive to copper than heterotrophs. Additionally, adverse effects on periphyton were observed at concentrations well below measures of chronic toxicity to organisms dependent on periphyton as a trophic resource and the chronic criteria for copper. As such, greater emphasis should be placed on the sensitivities of periphyton communities in future copper criteria determination. / Ph. D.

I investigated the baseline benthic macroinvertebrate community in relation to the environmental conditions in a section of Smith Creek, north of Harrisonburg, VA, prior to restoration. Quantitative benthic macroinvertebrate and environmental samples were collected in April and September 2006 from the Bruce Farm (BR) section of Smith Creek and the nearby Mixed Use (MU) section of Mountain Run. BR had been heavily used for cattle grazing for decades and suffered from sediment, nutrients, and lack of a forested riparian zone. MU had a forested riparian zone, but still received nutrient and sediment inputs from upstream cattle grazing. Visual habitat assessments were performed in September 2006 and were compared to quantitative measures. Benthic macroinvertebrate densities and taxa richness were greater at BR (total density for combined seasons = 52,438; taxa richness for both seasons = 84) than MU (total density for combined seasons = 3,982 and taxa richness for both seasons = 63). Biological environmental variables related to nutrients and growth of plants on rocks (ash-free dry mass, chlorophyll a, epilithic biomass) influenced the benthic macroinvertebrate assemblage more than physical environmental variables related to the substrate composition (% fines, % gravel, Trask's sorting coefficient). Visual habitat estimates were not as effective as quantitative measures of habitat for explaining the benthic macroinvertebrate assemblage. / Master of Science

A survey of the literature reveals little information concerning the aquatic fungi associated with submerged wood debris. During the past fifteen years several mycologists have studied such lignicolous fungi, but their efforts have been confined almost entirely to marine and brackish waters. It was thought that a study of similar organisms from fresh water would make a significant addition to our knowledge of aquatic fungi. This study involves the collection, identification, and description of freshwater lignicolous fungi from the area about Blacksburg, Virginia. To collect the fungi, sterilized panels of pine and poplar were submerged at six aquatic sites £or fifteen days or more. After submergence the wood was incubated in sterile moisture chambers and then examined with a dissecting microscope. Specimens of fungi found on the wood-surface were mounted and studied under high power. All of the collections are described in this paper, including those that could not be identified. Generic description have been adapted. Descriptions of species have been adapted and modified from the literature when they have seemed adequate, otherwise they are the author's own. Reproductive structures are illustrated. A key to the identified fungi is provided. The following fungi were identified and described: Dematiaceae - Alternaria sp., Bisporomyces chlamydosporis, Cacumisporium sp., Dictyosporium elegans, Dictyosporium sp., Gonytrichum macrocladum, Humicola sp., Leptographium sp., Monotospora megalospora, Piricauda sp., Septonema hormiscium, S. secedens, Sporidesmium caespitulosum, S. anglicum, Sporoschisma saccardoi, Trichocladium opacum; Moniliaceae - Arthrobotrys sp., Clathrosphaerina zalewski, Fusarium solani, Helicomyces roseus, Hobsonia mirabilis, Verticillium sp.; Tuberculariaceae - Bactrodesmium arnaudii; Sphaeropsidales - Aposphaeria agminalis, Asteromella sp., Coniothyrium sp., Stagonospora sp. (1), Stagonospora sp. (2); Actinomycetes - Nocardia sp.; Pyrenomycetes - Nectria sp. Two unidentified Dematiaceae and ten unidentified Pyrenomycetes were also collected and described. A comparison of the results of this study with the results of other investigations on aquatic fungi indicates the existence of a distinct aquatic mycoflora associated with wood. Aquatic Hyphomycetes have been extensively collected by other workers from submerged leaves and from pond and stream scum. None of the species, not even the genera, of those collections have been found in the present survey. No lignicolous Phycomycetes were found in the present survey, although aquatic Phycomycetes are known to grow on a vast array of substrates. The fresh-water population of lignicolous fungi may be fairly distinct from that of salt water. A survey of marine fungi reveals only five fungi - Alternaria sp., Dietyosporium elegans, Humicola sp., Trichocladium sp., Coniothyrium sp., Nectria sp. - that can be considered closely related to fungi found in the present study. This study provides some insight into the ecology of the fresh-water lignicolous fungi, although the study itself has beer, primarily taxonomic. Perhaps the most important problem now is to determine the actual habitat of these fungi. Research so far indicates only that they grow on wood and that their spores are carried in the water. Another problem is to investigate the nutrition of these organisms, to determine if they digest lignin and if they are unique in this regard. / Doctor of Philosophy

Architecture can amplify aspects of life. The proposal in this thesis is to present the nature of competitive swimming through four specifically defined architectural moments. The vehicle for the thesis is a natatorium with four specifically designed architectural apertures that present the extraordinary motion of the swimmer, especially to the younger general public. The focus will be on the motion of swimming below and above the surface of the water. Below the water surface, the approaching swimmer and the moment of the turn will be framed. Above the water surface, two apertures penetrate the roof above the pool. One directs sightlines to moment of a race's start, while the other seeks to emphasize the linearity of swimming. / Master of Architecture