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The relationships between brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), non-game fish populations and selected physical and chemical parameters were investigated in four streams draining the Blue Ridge Mountains in north-central Virginia during low flow conditions in August, 1981 and 1982. Multiple regression and discriminant function analysis identified average stream width and maximum stream temperature as the main environmental factors related to brook and brown trout abundance and distribution. Furthermore, consistent fish species assemblages relative to brown trout distribution were observed in the study streams. The movements of tagged brown trout in two streams were assessed for the period from June 1981 to July 1982. Most brown trout remained within 200 m of original tagging sections, 98.7% in the Conway River (78 out of 79) and 71.4% in the North Fork Thornton River (7 out of 9). The 1979, 1978 and 1977 year class fish (ages 2+, 3+ and 4+) exhibited extremely restricted movements and were invariably recaptured at original capture locations while the 1980 year class (age 1+) displayed small net upstream movements (<80 m) throughout the period. Two 1980 year class individuals displayed extensive movements (17.0 km downstream and 1.2 km upstream). These movements were characteristic of other stream resident brown trout populations. Results of this study suggest that brown trout may expand their range upstream into currently allopatric brook trout zones. It would likely be a slow but steady process which could be accelerated by infrequent long-range movements. The potential for establishment of reproducing brown trout populations and impacts of brown trout on native brook trout populations can be assessed utilizing fish species assemblages, average stream width and maximum stream temperature prior to further brown trout introductions in this region of Virginia. / Master of Science

Estuaries are unique coastal bodies of water where water derived from land meets the sea. In order to preserve estuaries and minimise the effects of human interference in these sensitive areas, an understanding of the hydrodynamics is essential. South Africa has 259 estuaries, of which approximately 70% are temporary open. The aim of the project was to provide data to analyse the effect of different flow scenarios on the frequency, timing and duration of mouth closure for temporary open estuaries. To achieve the project aim, two case studies were undertaken, namely Mhlanga and Mdloti Estuaries. Achieving the terms of reference required monitoring of the mouth state, water level, flow rates and developing an understanding of breaching mechanisms. Observations of the mouth were used to monitor its state and initially photographs were used to monitor the water level within each estuary. During 2003 a continuous water level monitor was developed and placed in each estuary. Velocity readings were taken upstream of the estuaries at discrete time intervals and converted to flow rates using the velocity area method. A photographic survey of the berm at Mhlanga Estuary was used to observe the effect of beach processes on the mouth area. The survey observed the estuary as it shifted from closed through to open, then partially open and finally closed again, providing information on mouth mechanisms. The continuous water level monitoring provides useful information for Mhlanga Estuary in terms of breaching patterns, tidal exchange when in the open state and an indication of the time scales involved in mechanisms which change the mouth state. Similar information for Mdloti Estuary was not available as the estuary did not breach since the installation of the water level monitors, however salinity profiles from 2002 provided qualitative information on the existence of a saline intrusion into the estuary. The relationship between flow and mouth state is complex and relies on other influences such as water level and systems losses. In general estuaries will breach under high flows and remain closed under low flows, however in between these two regimes the estuary mouth state is less predictable based on flow alone. Mhlanga Estuary repeatedly breached at low tide. During the open phase tidal influence was both observed and captured by water level monitors despite the perched nature of the estuary. Closure generally occurred at high tide trapping saline water within the estuary. The two case studies provided a good basis for exploring the affects of different flow conditions on estuaries, with Mdloti Estuary experiencing the effects of the Hazelmere Dam and abstractions, while Mhlanga Estuary has increased flow due to the discharge of treated effluent to the system. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2004.

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Flooding cycle in wetland rice (Oryza sativa L.) production systems is often subject to seasonal and cultural variations which may affect the availability and uptake of nitrogen in different ways. These factors may more or less influence the physiological and growth responses of the plant. In an effort to improve productivity in rice cropping systems, two controlled environment studies and a field trial were conducted to evaluate the growth and yield responses of rice to different flooding regimes and nitrogen fertilizer management strategies. In the first glasshouse trial, an upland cultivar (GM-1) was used to study the effects of four flooding regimes and three nitrogen application rates on the tillering, yield components and grain yield of rice. The field study determined the applicability of the results of the glasshouse trial to out-door environmental conditions, with the aim of gaining further insight into the impact of nitrogen application strategy on tiller and grain qualities. Two wetland cultivars (FKR-19 and N-19) and GM-1 were used to evaluate the effects of two flooding regimes and two nitrogen topdressing patterns. The second glasshouse trial determined the effect of hydro-priming on the establishment of direct seeded rice, and the effect of flooding on aerenchyma formation in rice roots. Results of the studies showed that flooding with standing water of 5 cm above the soil surface, irrespective of when it occurred, and nitrogen application increased the number of tillers and panicles, above ground dry matter, nitrogen uptake and grain yield of rice. However, late flooding and high nitrogen application rate of 220 kg ha-1 were found to encourage the production of late tillers, thereby reducing the efficiency of nitrogen use for grain production. Nitrogen application in three split doses tended to increase plant nitrogen content at heading; it slightly increased the protein content of the grains at maturity, but reduced the amylose content of the starch granules. Nitrogen application in two split doses led to increased grain yield in non-flooded plants, while the three-split treatment increased nitrogen uptake and grain yield in the flooded plants. Flooding significantly increased aerenchyma formation in the cortical tissues of rice roots, particularly at 50 mm behind the root tips. Hydro-priming seeds for 48 h improved plant establishment by shortening the germination and emergence times, and increasing the height and dry matter accumulation of seedlings, thereby ameliorating the susceptibility of rice to flooding stress. Overall, the thesis affirmed that controlled flooding is beneficial to rice production since it enhanced the growth and yield of the plant. It further revealed that early flooding and appropriate timing of moderate nitrogen application can ensure the conservation of water and nitrogen resources, including the quality of the environment, with no significant consequence for yield and productivity of the crop. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

This dissertation outlines the contribution of evolutionary and environmental factors on North American freshwater fish morphological variation. A more thorough understanding of the factors which result in morphological variation is essential to describing patterns of evolutionary diversification, distribution, ecological niche, ontogeny, sexual dimorphism, ecosystem role, community assembly, invasion dynamics, and conservation. This dissertation makes a unique contribution to understanding morphological diversity in freshwater fishes by linking intraspecific and interspecific variation to phylogeny, allometry, sex, habitat niche, geographic niche, hydrology, and long term environmental change. This dissertation is comprised of three chapters which detail large scale macroevolutionary patterns in morphological variation for North American freshwater fishes, long term morphological changes with hydrological alterations in Cyprinidae, and phenotypic plasticity of freshwater drum in the Wabash River. Overall, North American fishes tend to be deeper bodied and more robust with larger body size, in females, in low flow and lentic hydrological conditions, and in taxa with smaller geographic range that occupy more specialized habitat niches. Further, macroevolutionary analysis suggests that the majority of morphological diversification occurred relatively early on in the evolutionary history of North American fishes. / Evolution of North American freshwater fish morphology with variation in habitat use and geographic range -- 100 years of hydrologic alterations and morphological variation in Cyprinidae -- Effects of allometry, sex and river location on morphological variation of freshwater drum Aplodinotus grunniens in the Wabash River, USA. / Department of Biology

Operational planning of water resource systems like reservoirs and hydropower plants calls for real-time forecasting of reservoir inflow. Reservoir daily inflow forecasts provide a warning of impending floods or drought conditions and help to optimize operating policies for reservoir management based on a fine time scale. The aim of this study was to determine the best model for daily reservoir inflow prediction through linear regression, exponential smoothing and artificial neural network (ANN) techniques. The Hedi reservoir, the third largest reservoir in south China with a 1.144 x 109 m 3, was selected as the study site. The performance of these forecasting models, in terms of forecasting accuracy, efficiency of model development and adaptability for future prediction, were compared to one another. All models performed well during the dry season (inflow with low variability), while the non-linear ANNs were superior to other models in frontal rainy season and typhoon season (inflow with high variability). The performance of ANN models were hardly affected by the high degree of uncertainty and variability inherent to the rainy season. Stepwise selection was very helpful in identifying significant variables for regression models and ANNs. This procedure reduced ANN's size and greatly improved forecasting accuracy for ANN models. The impact of training data series, model architecture and network internal parameters on ANNs performances were also addressed in this study. The overall evaluation indicates that ANNs are an effective and robust tool for input-output mapping under more extreme and variable conditions. ANNs provide an alternative forecasting approach to conventional time series forecasting models for daily reservoir inflow prediction.

Copies of author's previously published articles inserted. / Bibliography: leaves 317-359. / xxii, 360 leaves : ill. (some col.), maps (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines the generality of the Flood Pulse Concept as a model for the role of flow in large floodplain rivers of all climatic zones and reviews the literature on hydrology-biology relations, with particular reference to the ecology of riverine fish. Using techniques of ordination, clustering and analysis of similarities (ANOSIM), examines the relations between flow variability, econology and climate in large rivers worldwide. Using a fie-year database for Cooper Creek in Central Australia, relates structures of fish, macroinvertebrate and zooplankton assemblages and indices of fish health and behaviour to hydrology at several spatial and temporal scales. These relations are established using multivariate techniques, univariate correlation and regression, and neural networks modelling. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1999

Copies of author's previously published articles inserted. / Bibliography: leaves 317-359. / xxii, 360 leaves : ill. (some col.), maps (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines the generality of the Flood Pulse Concept as a model for the role of flow in large floodplain rivers of all climatic zones and reviews the literature on hydrology-biology relations, with particular reference to the ecology of riverine fish. Using techniques of ordination, clustering and analysis of similarities (ANOSIM), examines the relations between flow variability, econology and climate in large rivers worldwide. Using a fie-year database for Cooper Creek in Central Australia, relates structures of fish, macroinvertebrate and zooplankton assemblages and indices of fish health and behaviour to hydrology at several spatial and temporal scales. These relations are established using multivariate techniques, univariate correlation and regression, and neural networks modelling. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1999

Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Sept. 23, 2009). Thesis advisor: John S. Schwartz. Vita. Includes bibliographical references.