No description available.

No description available.

This study is designed to (a) demonstrate the highly productive nature of the littoral area as compared to the pelagic region, (b) the possible importance of phyco-periphyton in the diets of fish, (c) the effects of meteorological conditions on distribution of phytoplankton, and (d) a demonstration of the invalidity of using artificial substrates as a universal means of measuring productivity.

PAHs are hydrophobic organic compounds, which have received considerable attention because of their high bioaccumulation, toxicity, carcinogenicity, and mutagenicity. Because of their hydrophobic characteristics, PAHs intent to adsorb on particles, most of PAHs contained in wastewaters are treated biologically, especially in activated sludge systems. But due to the low construction cost and high efficiency, macrophyte-based treatment systems received increasing attention lately. In this work, batch experiments were conducted to study the adsorption behaviors between the aquatic plant (Najas graminea Del.) and PAHs aqueous solutions, including acenaphthene (Acp), fluorene (Flu), phenanthrene (Phe) and pyrene (Pyr). The interactions between different PAHs and if the plant conditions affected the adsorption were also discussed. The kinetic studies showed that the more hydrophobic the PAHs are, the faster the equilibriums achieve, The kinetic constants were found to correlate with Kow. Linear adsorption isotherms were observed in all the adsorption experiments. The adsorption equilibrium constants (K) increase with the Kow indicates that the hydrophobicity of the PAHs dominates the adsorption behaviors. The existence of small mount of Pyr could lower the adsorption of Phe on the plant, while Flu couldn¡¦t. Because the hydrophobicity of Flu is too weak to compete with Phe, so the competition was not observed. The plant after dry process had even better performances in both kinetic and adsorption experiments, which provide more flexibility when put this technology into practice.

Parrotfeather [Myriophyllum aquaticum (Vellozo) Verdecourt] is a non-native aquatic plant from South America that was introduced into the United States in the 1890's. Research was conducted to elucidate seasonal life history, starch allocation patterns, and key environmental factors that may affect plant growth. Environmental factors identified in field studies were used to develop a conceptual model to display relationships between growth and environmental factors. The conceptual model served as a broad-based hypothesis to parameterize growth limiting factors as it related to M. aquaticum growth. Mesocosm experiments were then conducted to test relationships depicted in the model and define the growth requirements of this species. Emergent shoot biomass, submersed shoot biomass, and sediment root biomass were related to light transmittance. Submersed shoot biomass was also related to water temperature. Stolons accounted for 40-95% of total biomass. Starch allocation was also greatest in stolons (78.1 g m-2); where up to 16.3% of total starch was stored. Low points in biomass and starch occurred from October to March. Biomass was greater when plants were grown in 30% shade, whereas plant length was greatest when plants were grown in 50% shade, with reductions observed in full sunlight. Biomass increased by 53% when nitrogen and phosphorus were added to the water column at 1.80 and 0.01 mg L-1, respectively. Myriophyllum aquaticum yield response was positively related (r2 = 0.82) to increasing nitrogen content and a critical concentration of 1.80% nitrogen and 0.20% phosphorus was identified for M. aquaticum growth. Plants grown at 0 cm water depth had 96% greater biomass than plants grown at water depths of 137 cm. Total length was 25% greater when plants were grown at water levels from 0-77 cm. Winter drawdowns reduced biomass by 99% at 4 weeks when compared to pre drawdown biomass. Summer drawdown efficacy was more rapid where biomass was reduced by 98% at 2 weeks when compared to pre drawdown biomass. Subsurface herbicide applications were not more efficacious than herbicides applied to the foliage. The foliar application of 2,4-D was the only herbicide and application method that resulted in ¡Ý90% biomass reduction of M. aquaticum.

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.

Aquatic vegetation plays an important role in the ecological interactions and processes within a water body. However, the presence of the invasive exotic aquatic plant species, waterhyacinth [Eichhornia crassipes (Mart.) Solms], negatively affects those interactions as well as interfering with water use for recreation and navigation. An implemented management plan for waterhyacinth control relies on the use of herbicides. Efficacy is commonly assessed using visual injury and control ratings as well as estimating biomass. The problem is that those approaches are labor intensive only assessing single points throughout the entire water body. Therefore, technology like remote sensing, which is the focus of this research, is recommended as an additional tool to assess implemented management plans. Studies were conducted in a mesocosm research facility to evaluate the relationship between simulated spectral bands 3, 4, 5, and 7 Landsat 5 TM and waterhyacinth treated with the herbicides imazapyr and glyphosate. Results indicate that injury is better detected and predicted with band 4 and that relationship is negative when either herbicide was used. However, prediction is better when plants have developed sufficient injury to influence the spectral response of band 4. In the second study, the biomass of waterhyacinth was estimated using the Normalized Difference Vegetation Index (NDVI) using simulated data from Landsat 5 TM. This study was conducted over natural populations of waterhyacinth in Lakes Columbus and Aberdeen, MS over two growing seasons. Results indicate that the use of NDVI alone is a weak predictor of biomass; however, its combination with morphometric parameters like leaf area index enhanced predictive capabilities.In order to assess field herbicide treatments for waterhyacinth control and its consequent impact on native aquatic vegetation, lake-wide surveys were performed in Lake Columbus, MS using a point-intercept method. The herbicide assessed was 2,4-D which was applied aerially and by boats. Point-intercept surveys in a 400 by 400 grid of points aided with global positioning system (GPS) were performed before and after herbicide treatments. Obtained results indicate that the frequency of occurrence of waterhyacinth significantly decreased after herbicide treatments which consequently led to the reestablishment of native aquatic vegetation on the system.

In Taiwan, swine wastewater has become one of the major causes of the deterioration of surface water quality. To minimize the operational and maintenance cost of the conventional wastewater treatment utilities, less expensive natural treatment systems (e.g., aquatic plant treatment system) have been proposed to enhance the efficacy of existing three-stage treatment system (solid separation followed by anaerobic and aerobic treatment). Using the natural treatment system is an appropriate technology for treating livestock wastewater in tropical or subtropical regions or developing countries because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The main objectives of this study were to (1) examine the efficacy and capacity of using aquatic plant treatment system to polish the treated wastewater to meet the discharge standards in Taiwan (COD = 600 mg/L, BOD = 80 mg/L, and SS = 150 mg/L), (2) evaluate the potential of reusing the treated wastewater, (3) evaluate the feasibility of replacing the aerobic treatment process contained in the three-stage system with the aquatic plant system, and (4) improve the efficiency of sludge (obtained from the three-stage treatment system) composting process. In this study, a hog farm was selected as the case study site. An aquatic plant unit [13.5 (L) ¡Ñ 4 (W) ¡Ñ 3 (D)] planted with Eichhornia crassipes (water hyacinth) was placed after the aerobic system for wastewater polishment. Influent and effluent sa mples from each unit were collected and analyzed for water quality parameters including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and suspended solids (SS). Water samples were collected monthly during the 15-month investigation period. Results show that the averaged COD, BOD, and SS concentrations were approximately 708, 83, and 123 mg/L, respectively after the three-stage treatment scheme. The observed COD, BOD, and SS concentrations dropped to 518, 56, and 48 mg/L, respectively which could meet the discharge standards. Thus, the aquatic plant treatment system played an important role in meeting the discharge standards for swine wastewater. More than 99% of all pollutants were removed by the three-stage system followed by the aquatic plant system. The effluent from the treatment system has been used for hog farm cleaning. Thus, the aquatic plant system has the potential to be applied as the final polishment process to enhance the treatment efficacy of swine wastewater. Results also show that it is feasible to replace the aerobic treatment process with the aquatic plant system from the cost and regulation compliance point of view. Results from the composting study show that rice straws could enhance the activity of microorganisms and also cause the increase the quantity of potassium in the compost pile. Moreover, mixing the water hyacinth in the compost pile could increase the quantity of nitrogen and phosphorous. Results also reveal that using ceramic bioballs as the filling materials could minimize the composting time due to the increase of permeability in the piles.

Fungal communities of aquatic ecosystems are understudied, leaving major gaps in estimating global fungal biodiversity. In particular, little is known regarding the distinctiveness of (1) aquatic endophytes vs. those in terrestrial plants, and (2) waterborne fungi vs. those inhabiting aquatic plants or sediments. I assessed the diversity, composition, host affiliations, and geographic structure of culturable endophytes associated with aquatic angiosperms in reservoirs in northern Arizona, and their distinctiveness relative to waterborne- and sediment fungi. Endophytes were low in abundance yet extremely diverse. Communities differed significantly in composition among reservoirs and tissues. Aquatic endophytes were largely distinct from those in terrestrial plants, and from those in water and sediment, but did not demonstrate host specificity. This work reveals the uncommon diversity and distinctiveness of endophytes in aquatic plants, and provides a first quantitative estimation of endophytic associations in diverse, ecologically important, and economically relevant aquatic plants.

This thesis looks into the use of historical macrophyte records to assess long term changes in macrophyte communities in lakes and potential reasons for these changes. In particular it uses historical records to assess changes in macrophyte communities in the Norfolk Broads and West Midland Meres, two sets of lowland, eutrophic lakes in England. It provides a critical examination of the use of historical records, highlighting some of the constraints common to such data such as variations in recording effort, and bias in species recording and site selection. Having acknowledged these issues we then go on to develop a robust way to interpret such data, using a “change index” based on species persistence over the last 200 years within individual lakes. Species with high change index values, which represented species which had persisted or increased within the lake districts, were those known to be characteristic of eutrophic lakes. Conversely species with low index scores, which had declined in both the broads and meres over the last 200 years, included species associated with less fertile conditions but also a selection of typically eutrophic species. Averaging of change index scores in present day survey data served to identify the historically least changed lakes and to rank lakes in order of degree of botanical change over the last century. We then analysed the ecological basis of the change index in order to better understand the processes behind the decline of some species and survival of others in the Norfolk Broads and West Midland Meres. Functional groups determined from morphological and regenerative traits displayed significant differences in change index values in both groups of lakes, but declining taxa occurred across a wide range of plant growth forms. Non-hierarchical clustering of species based on their ecological preferences, obtained from published literature, resulted in groups with distinct change index values, indicating that changes in the status of species could be partly explained by these preferences. Of these, trophic preference was consistently the most important, with species of less fertile habitats consistently experiencing the greatest declines. However, some characteristically eutrophic species have also declined significantly, particularly in the broads. In these cases increasing loss of shallow water, low energy habitats in the broads, or loss of fluctuating water levels and less alkaline backwaters in the meres, appear to have been contributory factors. In addition to the change index approach, we also used historical records at a site level to complement palaeolimnological analysis and investigate the change in macrophyte community composition and structure at Barton Broad, Norfolk. Sediment samples were extracted from the bottom of the broad and analysed for sub-fossil remains and pollen of macrophytes. The historical records and palaeolimnological analysis combined showed that early communities did not consist entirely of low growing, oligotrophic and mesotrophic species as previously thought, but in fact comprised a mixture of these and other more characteristically high nutrient species associated with taller, or free-floating growth habit. As eutrophication progressed throughout the last century, the community was increasingly dominated by these latter growth forms. Diversity was maintained, however, since encroaching reedswamp generated a mosaic of low energy habitats which supported a range of species unable to withstand the hydraulic forces associated with more open water habitat. When the reedswamp disappeared in the 1950s, many of the dependent aquatic macrophytes also declined resulting in widespread macrophyte loss. The thesis demonstrates not just the complexities of using historical records, but also ways in which these can be overcome to make useful observations about macrophyte community change and lake ecological integrity to inform conservation and lake management, both on a site and lake district level.