Identifying the ecological mechanisms that determine food web structure is critical for understanding the causes and consequences of diversity. The objective of this thesis was to identify the mechanisms structuring aquatic food webs across environmental gradients from a multi-level perspective (individual to ecosystem) using integrative methodology and field experiments to test classic ecological theory. My results demonstrate support for the dynamic constraints hypothesis, which predicts habitats with greater disturbance should have shorter food chains, but are not consistent with the ecosystem size hypothesis that predicts larger ecosystems have longer food chains. Insect and amphibian richness increased with increasing pond size and hydroperiod, indicating that insertion of new consumers into pond communities was driving variation in food-chain length. A multivariate analysis testing the influence of physicochemical variables on food-web characteristics revealed that hydroperiod and pond area had a strong influence on amphibian and invertebrate assemblages, trophic diversity and 15N range. Food-chain length did not respond strongly to any one variable, but instead responded weakly to multiple environmental variables, suggesting interacting influences on food-web structure. Conversely, the trophic niche of amphibian larvae was not influenced by pond hydroperiod, but did exhibit ontogenetic diet shifts. Populations of amphibian larvae with broader niche widths also had increased individual variation, supporting the niche variation hypothesis. In addition, I assessed whether species diversity influenced the magnitude of cross-habitat resource flow between aquatic and terrestrial habitats via emerging aquatic insects, metamorphosing amphibians, and litter deposition. Deposition into ponds far exceeded carbon exported via insect and amphibian emergences. We found a negative relationship between resource flux and the diversity of amphibians and insects, which contradicts the general pattern of positive biodiversity-ecosystem function relationships. My research strongly suggests environmental variation is a key process in shaping food-web structure and function and that multiple methodologies are needed to understand temporal and spatial dynamics of aquatic ecosystems.

Along the Toronto shoreline, small coastal embayments (0.4 – 32 ha) are being constructed or modified to restore warmwater fish habitat. I describe how Lake Ontario (hereafter the Lake) alters the thermal regime of these small coastal embayments, how the altered thermal regimes affect growth and survival of age-0 warmwater fishes, and how the thermal habitat quality for such fishes can be improved by altering embayment design. During the warming period of the ice-free season, embayments warm faster than the Lake and so are cooled by exchanges with the Lake. Later in the year Lake exchange warms the rapidly cooling embayments, but the net effect of Lake-embayment exchange is cooling. The degree of cooling in Toronto’s small coastal embayments varies; many have temperatures near that of the Lake, and a few warm as much as local ponds. Age-0 pumpkinseed (Lepomis gibbosus) can fail to reach sufficient size to survive the winter in cooler embayments because their spawning is delayed and their growth is slowed. Most embayments along the Toronto shoreline are too cold to produce age-0 fish that can survive the winter, but all embayments are occupied by age >1 pumpkinseed, suggesting movement from warmer to cooler embayments. Using otolith microchemistry to identify natal embayments of fish, I confirm that age-0 and age-1 pumpkinseed, as well as age-0 largemouth bass (Micropterus salmoides) and age-0 yellow perch (Perca flavescens), exist in metapopulations. Embayment bathymetry is a poor predictor of temperature because almost all embayment flushing rates are very fast, usually 1-2 days. Warmer embayments are located in protected areas of Lake Ontario and receive waters that have already heated substantially. Cold embayments are located along the exposed shoreline of Lake Ontario. To protect embayments from cold lake waters, the cross-sectional area of embayment channels need to be reduced to 1-10% of their current size.

This project examines the spatial relationships that exist between Winnipeg, Canada and Tokyo, Japan, with the intent to develop an understanding of the preciseness of the world. Different site-specific systemic conditions were used as critical tools to explore the implication of distinct design catalysts and inhibitors. I have concentrated on the relationships that exist between time and space, to identify and displace localized, momentary events that exist in one site to the other. Familiarities of my local surroundings were deliberately obscured to make explicit a heightened awareness of my position on the planet. This helps to facilitate discussions. I have created a space that is dissembled through abstract understandings of displaced elements in the environment. It is my intention for this space to be experienced in a different way each time we come across it, by shifting and changing ones perception of their character in the world. / October 2008

In 1970,China carry out economic reform policy, development export-oriented agriculture, because of having the advantage of low-cost labor and land resource, loosen economic control and attract foreign capital investment gradually. In 1980, Taiwan entrepreneur start to investment agriculture related industry in China, and to bring in technology improved seed. but reviews the home, because environmental consciousness, the factory moves gradually toward the Southeast Asian country and China.Comparatively speaking, our country competitive power has the drop tendency. Separately, Taiwan and China joined one after another in WTO about in 2002, affect product wish of our country farmer because possible the low price to rob the market. We discuss bilateral in international market sales situation, the export market comparison from the Taiwan ten main aquatic products, the result discovered that the Taiwan most aquatic products all substitute by China, the government must propose in accordance to the plan and achieves the industry to continue forever to manage.

Invasive aquatic species such as Hydrilla verticillata (hydrilla) have become a pervasive and nearly ineradicable part of the waterways of the American south. Hydrilla is an aggressive colonizer; grows rapidly and rapidly blocks flow areas, which greatly reduces the capacity of water supply canals. Hydrilla grows up through the water column and is present throughout flow zones that are typically assumed to be free flowing and without resistance, other than that transmitted via the mechanics of a Newtonian fluid. Hydrilla is highly flexible and its morphology in the flow field is dependent on many parameters, including flow, growth stage, cross-section geometry and substrate. Traditional methods of calculating canal flow capacities assume that resistance to flow originates at the boundary of the channel. These methods typically attempt to account for vegetation by increasing resistance coefficients, which are associated with the boundary of the canal. A combination of field studies and experimentation in three separate laboratory channels was used to characterize the behavior of hydrilla and its impacts on open-channel flow. This work developed relationships for energy losses of flow within the vegetation, as well as velocity gradients within the vegetation and through the vegetation water interface to the open water. The information developed in this investigation was used to develop a model of the cross-section of flow with vegetation growing in the center of the channel. The model is based on the Prandtlvon Kármán universal-velocity-distribution law; and uses modifications to the method of calculating the hydraulic radius, to account for the increased frictional elements and reduced flow areas in the canal cross-section. A simple function was developed to estimate the remaining flow capacity in a canal as a function of the remaining unblocked area. The Prandtl-von Kármán universal-velocity-distribution law, together with modifications to the method for calculating the hydraulic radius, can improve estimates of the flow in channels impacted by submerged aquatic vegetation. The effects of a broad range of parameters can thus be represented by a relatively simple function, which was developed in this project.

Loss of wetland habitats across the nation is staggering and continues, especially in urbanizing areas. Thus, wetland restoration has become a priority. However, questions remain regarding system function and biotic communities. We studied a constructed floodplain wetland complex near Dallas, Texas. We sought to improve understanding of wetland ecosystem development under the influence of different approaches to wetland restoration in an urbanizing landscape. In the wetland complex, 10 constructed sloughs, approximately 70m by 15m, were designated for this study. Our experiment monitored the establishment of aquatic plant and invertebrate communities under different experimental conditions. In 5 sloughs, 5 native perennial hydrophyte species were transplanted in blocks in each slough, with the remaining 5 sloughs unplanted. Portions of each slough were caged to determine the effects of protective caging. Using 1m2 caged and neighboring uncaged areas as quadrats, we sampled vegetation and the invertebrate community over two years to determine the effects of restoration treatmentsSlough planting did not result in statistically different levels of plant cover. However, invertebrate abundance was greater in planted sloughs, and plant composition was different, comprised more of perennial species in planted sloughs than in unplanted sloughs. Caging did not have an effect on plant or invertebrate communities. However, changes due to time resulted in significant increases in plant cover and invertebrate abundance and shifts in community composition. Four of 5 transplanted species were emergent growth forms. Emergent cover and the remaining species, Potamogeton nodosus, a floating-leafed plant, accounted for invertebrate community variation. Transplanted emergent species did not fare well, though other emergent species did colonize the site, along with widespread coverage by submerged Najas guadalupensis. Potamogeton spread rapidly, colonizing unplanted sloughs, and this will likely affect community development across the site. Plant and invertebrate richness values were low, likely due to hydrological extremes and the short period of time since construction. Water level fluctuations resulted in plant communities dominated by obligate wetland plants, though drought stress took a toll on survival of plants and invertebrates in late summer. Community development and system function were dependent mostly upon time and hydrology. on the communities.

Electroplating industry is one important industries in Taiwan. Its wastewater has lead to pollution of the river, ocean, and underground water. Thus, the reduction of the concentration of heavy metals such as Cu, Zn, Ni, Cr, Pb etc. from wastewater is critical. Conventional strategies to remove the heavy metals involve adding abundant chemical agents which results in largy quantity of heavy metal sludge. Secondary pollution might occur as due to the heavy metal sludge contacted with acid. Aquatic plants have been shown to uptake the heavy metals from the surrounding environment. This unique character is different from the conventional approach and could be applied for removing the heavy metals in wastewater.This study used an aquatic plant, Najas graminea Del, to remove the heavy metals from the prepared metal solution and electroplating wastewater. Our data revealed that the relationship between the specific adsorption and residual concentration of the heavy metal was best described by the Langmiur adsorption isotherm curve. The value of maximal adsorption capacity (Ymax) in copper is 58.1 mg/g. Without buffering, the sequential order for the Ymax in the prepared metal solution is Cu > Pb > Cd> Ni > Zn. The value of Ymax was with significantly reduced under buffering circumstance as compared with that no buffer. In the electroplating wastewater containnig copper from company A, the value of Ymax was 20.7 mg/g, which was much smaller in prepared copper solution (Ymax =33.1 mg/g). Our further investigation showed that the background contaminatants especially iron in the electroplating wastewater have significant contribution to this discrepancy. In other set of experiments, we found that there is no significant difference between the electroplating wastewater and prepared solution for the adsorption of Ni. Our results provide useful information the understanding the process for the Najas graminea in adsorption the heavy metals from electroplating wastewater. Futhermore, the application of Najas graminea to remove the pollution from wastewater can protect the enviroment from pollution. This innovative concept has the potential in practical application and could be trasferred into a novel technology to substitute the conventionally physical or chemical treatment for the electroplating wastewater.

In the process of pursuing economic growth as the national target for a long time, Taiwan has created an economic miracle but sacrificed ecological environmental sources. With increasing higher living standards, more living space is demanded such that providing clean and green spaces along riverbanks in addition to offering security becomes another important mission. In recent years, the global thinking of sustainable development has demanded more ecological and environmental protection such that efficient management of waters along river, drainage and seacoast will be emphasized tasks of watershed management. The main objective of pollution investigation and quantity estimation in Chiang-Chun River watershed is to effectively comprehend the sources of pollution to assist in establishing the water quality model to be used in simulation. The QUAL2E model developed by the US EPA is used to carried out estimating the carrying capacity of Chiang-Chun River, and drafting pollution control measures and waste reduction strategies so that the objective of improving Chiang-Chun River¡¦s water quality can be achieved. Chiang-Chun River has long been subjected to pollutions from industrial and domestic waste discharges resulting in serious water quality deterioration. Additionally the waste discharge from manufacturing plants along the creek has made the pollution even worse. Hence, various environmental protection authorities have actively promoted the checking and controlling industrial and pig-farming wastewater discharges and established a mechanism encouraging local residents to participate in the watershed pollution prevention and control. These measures will not only alleviate the water pollution in Chiang-Chun River with limited resources but also achieve the purpose of communing local residents and the river. V The livestock wastewater is currently treated in three-stage system including solid-liquid separation, anaerobic treatment and aerobic treatment. With good management, the effluent is expected to meet discharge standards. However, since most pig farmers, who may try to save costs, have not efficiently managed the treatment facility so that the treated effluent does not meet the standards. If directly discharged into surface bodies, the improperly treated effluent will cause serious pollution problems. A natural treatment and water purification system is currently being promoted. If implemented in the three-stage treatment system, the natural system (aquatic treatment system) will achieve energy savings, lower the difficulty to operate the treatment system and reduce the operation and maintenance costs. Additionally, effluent quality can be improved such that the possibility of water reuse is also expected. Providing adequate treatment for domestic wastewater requires the construction of sewage system, which is costly and may take a long time to complete. Additionally, since most residents are scattered in the watershed, the construction of conventional sewage system to collect domestic wastewater is not cost-effective. Hence, the natural system, e.g. constructed wetland, is proposed as the major method for treating the wastewater discharged from communities and for achieving water reuse such that multiple-functional benefits can be reached. Additionally, the concept and tasks of water pollution prevention and control can be deeply rooted in the community development so that a community possessing the capability of water self-purification and sustainable application is developed.

Following the economy growth and commercial and industrial development, the rivers in Taiwan have suffered the environmental degradation due to the overwhelming pollution from domestic and industrial sewage. Recent environmental awareness from the citizen has turned the once ignored issues of pollution mitigation and ecological restoration into the public attention. Traditionally, resort to engineering efforts is always the first priority in dealing with river pollution problem. Nevertheless, treated as the integrated system, the nature of the problem should involve many aspects including social, economic, ecological, environmental, and engineering factors. Meanwhile, the special feature of time-dependent state has also made such system a dynamic and complex problem. It is therefore the current research employs the approach from integrated assessment trying to aggregate related studies and tackling the problem as a complete system. System dynamic, which is capable of dealing with dynamic and complex problems, has been utilized as the simulation tool in this research. The result from computer simulation can be promptly generated, and various scenario analyses can be easily achieved by modifying the model parameters to support better decision-making. Love River wandering through the Kaohsiung metropolitan area is the research target. The system dynamic software STELLA has been used to construct the simulation model, which incorporates water quality model, population growth in the upstream of the watershed, land use variation due to the assumed regional development, diverse rainfall types, ecological assessment of the domestic fishes in the river, and cost-benefit of various pollution control strategies. The system dynamic models are thus able to evaluate the overall impact on the aquatic environment between various management scenarios. Two types of system dynamic models are constructed and verified accordingly to evaluate the impact of the designate gate operations and the sewage treatment strategies on aquatic environment. The simulation based on the gate operation model shows that keeping upper stream gates shut during the initial time span of a rainfall event would have the better effect to prolong the concentration of dissolved oxygen (DO) downs to the lethal concentration (LC50) for the local fish species. In the sewage treatment strategies model, the treatment cost and effect is the primary concern. The results identify the better extending strategy on the treatment plant, which is to use fortified primary treatment by adding disinfectant facilities. The other scenario of building constructed wetland system on the public park can improve water quality with good cost/effect ratio given the land acquisition is not an issue. Keyword¡GIntegrated Assessment, System Dynamic, Sustainable River Aquatic Environment

Nutrient availability and herbivory can regulate primary production in ecosystems, but little is known about how, or whether, they may interact with one another. Here I investigate how nitrogen availability and insect herbivory interact to alter above- and belowground plant community biomass in an old-field ecosystem. In 2004, 36 experimental plots were established in which soil nitrogen (N) availability (at three levels) was manipulated and insect abundance (at two levels) in a completely randomized plot design. In 2009, after six years of treatment, I measured aboveground biomass and assessed root production at peak growth. Overall, I found a significant effect of soil N availability on both above- and belowground plant biomass while insects affected only aboveground biomass of subdominant plant species and coarse root production; there were no statistical interactions between N availability and insect herbivory for any response variable. Specifically, responses of aboveground and belowground community biomass to nutrients were driven by reductions in soil N, but not additions, indicating that soil N may not be primarily limiting production in this ecosystem. Insect herbivory altered the aboveground biomass of the subdominant plant species and altered allocation patterns to coarse root production belowground. Overall, the results of six years of nutrient amendments and insect removals suggest strong bottom-up influences on total plant community productivity.