The avian influenza virus can be transmitted from sick birds to other birds by fecal and oral secretion. Therefore, when birds with avian influenza virus enter domestic bird farms and make contacts, it is possible to carry the virus in and transmit it to domestic birds. Since the outbreak of the avian influenza in Taiwan, most bird farms had set up the screen. Yet, the actual effectiveness of screen coverage rate has not been researched. This study will discuss further regarding the results of different screen coverage rate in preventing wild birds¡¦ entering to poultry farms in Kaohsiung area. Field observations were carried out at the wetlands in Kaohsiung county, including Old Railroad Bridge artificial wetland, Fongshan reservoir and 20 poultry farms which were less than five kilometers away from wetlands from September 2008 to October 2009. Chicken and duck farms were analyzed respectively, and the screen coverage rate was categorized into full, partial and no coverage, respectively. The aims of the study were to investigate the effect of screen coverage on the entrance of wild birds to the farms, and found out the potential bridge species near poultry farms. By observing different levels of screen coverage in poultry farms, migratory birds¡¦ activity, and the contact situation between wild and domestic birds, we can analyze the contact level of high risk species and speculate possible transmission path of the avian influenza, and understand the effectiveness of the screens. Also, showing the correlation between the density of domestic poultry and the number of wild bird enterance. The result showed, in terms of screen with different coverage rates, the number of bird species within the duck farms had significant different in full and no coverage. The number of total birds within the duck and chicken farms with full coverage was significant less than partial coverage. Both in chicken and farms, screen had a great effectively in preventing small sized birds entering, yet not on big sized birds. The density of domestic poultry and the number of wild bird enterance showed negative correlation only in chicken farms with partial coverage. In terms of the wild land birds entering poultry farms, Passeer montanus is the largest species, followed by Hirundo rustica and Streptopelia tranquebarica. As for aquatic birds, it is mainly of Ardeidae, Scolopacidae, Charadriidae and Rallidae. Among all, Passeer montanus, Hirundo rustica, Streptopelia tranquebarica, and Bubulcus ibis are not migratory birds and highly pathogenic avian influenza virus species which move between poultry farms and wetlands. Therefore, they were considered bridge species. Due to the bridge species makes direct contacts with poultry, it might be the spreader of the virus. Decreasing the possibility of wild birds¡¦ contact with poultry is an important mechanism for avian influenza control. Also, based on the model of European Food Safety Authority (ESFA), risk assessments will be conducted on Kaohsiung County wetland¡¦s migratory birds¡¦ highly pathogenic avian influenza virus H5N1 transmission to poultry farms.

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This dissertation investigated locational risks to ecosystem health associated with proximity to industrial complexes. The study was performed at the behest of ranchers and citizens living and working down-prevailing wind from the Formosa Plastics, Inc. and ALCOA facilities located in Calhoun County, Texas. Concerns expressed were for potential genotoxicity resulting from exposure to complex chemical mixtures released by the facilities. Exposure assessment of the marine environment was performed with sediments and oysters from Lavaca Bay being analyzed. Numerous chemicals were found to be present at concentrations considered likely to result in adverse responses in exposed populations. Bayesian geostatistical analysis was performed to determine if the concentrations were affected by a spatial process. Mercury and polycyclic aromatic hydrocarbons were the most notable of the chemicals found to be present at elevated concentrations and affected by a spatial process. Evaluation of maps generated from spatial modeling revealed that proximity to ALCOA resulted in elevated risks for exposure to harmful concentrations of pollutants. Genotoxicity was measured in two sentinel species. Oysters (Crassostrea virginica) were utilized for evaluation of the marine environment and cattle (Bos taurus and Bos taurus crossbred cattle) were chosen for evaluation of the terrestrial environment. Chromosomal aberration analysis was performed on oyster hematocytes. Analysis of the results failed to demonstrate the presence of an important generalized spatial process but some specific locations close to the ALCOA plant had elevations in this measure of genotoxicity. Stress as measured by the lysosomal destabilization assay was also performed on oyster hematocytes. These results were found to be affected by a significant spatial process with the highest degree of destabilization occurring in close proximity to ALCOA. Genotoxicity in cattle was evaluated with the single cell gel electrophoresis assay and chromosomal aberration analysis. Bayesian geostatistical analyis revealed the presence of important spatial processes. DNA-protein cross-linkage was the most notable with a strong indication of increased damage down-prevailing wind from the industrial complexes. Results indicated that proximity to industrial facilities increased the risk for harmful exposures, genotoxicity, and lysosomal destabilization.

The purpose of this study was to determine how manatees use Swallow Caye, Drowned Cayes, and Gallows Reef, three distinct habitat types within the Belize Barrier Reef lagoon system near Belize City. Data were collected using boat-based point scan methods with the assistance of volunteers. Presence/absence and photo ID methods ensured consistency of data collection despite a changing pool of volunteer researchers. Results confirmed the mangrove and seagrass ecosystem between the Belize Barrier Reef and Belize City as important manatee habitat. Inconsistent with the prevailing "seasonal distribution hypothesis" for manatees in Belize, the probability of encountering manatees at Swallow Caye and in the Drowned Cayes was equal between dry and wet seasons. However, manatees were only observed at Gallows Reef during the wet season. Swallow Caye had the highest probability of encountering manatees, confirming traditional knowledge held by local tour operators, which led to the establishment of Swallow Caye Wildlife Sanctuary in 2002. In contrast to previous studies, my data suggest that at least 44% of the manatee population carry scars from non-lethal boat strikes. The proportion of scarred animals did not vary as a function of habitat type, season, or year. The probability of encountering manatees did not change between years, despite an exponential increase in cruise ship tourism. Marine Protected Areas (MPAs) and wildlife protection laws indicate that Belize is working to meet obligations under international agreements. However, there is still cause for concern. Manatees do not remain inside designated refuge boundaries; governmental agencies depend on co-management agreements with local non-governmental organizations for enforcement of rules inside MPAs; regulations governing human behavior outside MPAs are lacking; funds for monitoring and evaluation of MPAs are lacking. Manatee conservation strategies should be integrated into a system of riverine, coastal, and marine protected areas supported by additional tactics such as required manatee training for boat captains, slow zones at hot spots outside MPAs, and continued educational outreach. With few modifications and increased enforcement and monitoring, the Belize model for manatee conservation could lead to a shared "triumph on the commons" for the manatees and the user groups that shared their habitat.

Understanding the influence of environment and correlation/relationships among traits is necessary in selection for crop quality improvement. Therefore, correlations among antioxidant activity (AOA), total phenolics (TP), phenolic composition, and specific gravity (SPG) in four potato (Solanum tuberosum, L.) cultivars (Atlantic, Red La Soda, Russet Norkotah, and Yukon Gold) grown in nine states (California, Idaho, Michigan, Minnesota, New Jersey, North Carolina, Oregon, Texas, and Wisconsin) for three years, and in 15 advanced selections grown in Texas were investigated. Cultivars within and between locations were significantly different in AOA, TP, and SPG. Significant effects of cultivar, year, location and their interactions on AOA, TP, and SPG were observed. There were significant positive correlations among the four cultivars between AOA and TP, and negative correlations between AOA and SPG, and between TP and SPG. However, correlations between AOA and SPG, and between TP and SPG, in the advanced selections were not significant. Some tuber-bearing wild potato species were higher in AOA and TP than the commercial cultivars; therefore, they could be used as parental material in breeding for high AOA and TP. However, use of wild species that might be higher in total glycoalkaloids (TGA) than cultivars could result in progenies with high TGA if the traits are positively correlated. To elucidate the relationships among AOA, TP and TGA, accessions of Solanum jamesii and S. microdontum from the US Potato Genebank were screened for these traits and their correlations determined. Also, anti-proliferative and cytotoxic effects of 15 S. jamesii tuber extracts (5 and 10 μg/ml) on human prostate (LNCaP) and colon (HT-29) cancer cells was determined in vitro. Alpha-solanine and α-chaconine were found in both species, while tomatine and dehydrotomatine were quantified in some S. microdontum accessions. Both species were higher in all above traits than the Atlantic, Red La Soda, and Yukon Gold cultivars. More than 90% of S. jamesii accessions had TGA levels < 20 mg/100g fresh weight, while only two accessions of S. microdontum, P1 500041 and PI 473171, exhibited TGA < 20 mg/100g. Neither AOA nor TP was significantly correlated with TGA in both species. Also, individual phenolics were not correlated with TGA. Solanum jamesii accessions significantly reduced proliferation of HT-29 (5 and 10μg/ml) and LNCaP (10μg/ml) cells and were not cytotoxic compared to the control (DMSO). Therefore, since AOA and TP were not found to be correlated with TGA, using wild accessions in breeding for increased health promoting compounds would not necessarily increase glycoalkaloids in newly developed potato cultivars.

The goal of my dissertation was to describe the dynamics of a group of Houston toads located at the Griffith League Ranch (GLR), Bastrop County, Texas. My research included using statistical modeling to predict activity and abundance, mark-recapture techniques to estimate survivorship, and simulation modeling to explore the impacts of the difference in age at first reproduction and to project the future dynamics of the population at the GLR. From 2001 – 2005, 225 individual Houston toads (199 M : 26 F) were captured using two methods: breeding pond surveys and drift fences. Houston toads were neither caught equally among capture methods, nor across years. Toad activity was mostly confined within their breeding season, and activity was not continuous. A logistic regression indicated activity depended on time of year, mean precipitation, mean minimum daily temperature, and mean percent lunation as well as two-way interactions with moon-phase and other variables. Abundance depended on time of year, current precipitation, minimum temperature, and two-way interactions between time of year and the other two variables. Twenty-one of the 199 males (10.5%) and no females were recaptured among years. The probability of male survival was estimated using program MARK. Eight of 16 candidate models were supported and all but one contained precipitation as a covariate, indicating precipitation is important for Houston toad survival. Survivorship estimates varied from 0.1 to 0.41. The sex ratio was significantly male-biased. The odds of catching females in traps were 3.5 greater than capturing females in a pond, while the odds of capturing males in a trap were 0.28 compared to ponds. Results from a simulation model indicated the sex ratio is biased because of the difference in maturation times between males and females, coupled with high juvenile mortality. Results from an individual-based, spatially-explicit, stochastic simulation model, indicated a relatively low probability (~ 0.013) of B. houstonensis going extinct at the GLR within the next 10 years. Emergent properties of the model were similar to results observed in the field or reported in the literature. The model also identified that dispersal of Houston toads should be a future research priority.

Biogeographic patterns across a landscape are developed by the interplay of environmental processes operating at different spatial and temporal scales. This research investigated dynamics of salt marsh vegetation on the Skallingen salt marsh in Denmark responding to environmental variations at large, medium, and fine scales along both spatial and temporal spectrums. At the broad scale, this research addressed the importance of wind-induced rise of the sea surface in such biogeographic changes. A new hypothetical chain was suggested: recent trends in the North Atlantic Oscillation index toward its positive phase have led to increased storminess and wind tides on the ocean surface, resulting in increased frequency, duration, and magnitude of submergence and, hence, waterlogging of marsh soils and plants, which has retarded ecological succession. At the mid-scale, spatial patterns of vegetation and environmental factors were examined across tidal creeks. Sites closer to tidal creeks, compared to marsh interiors, were characterized by the dominance of later-successional species, higher bulk density, and lower nutrient contents and electrical conductivity. This finding implies that locations near creeks have experienced a better drainage condition than the inner marshes, which eventually facilitated the establishment of later-successional plants that are intolerant to physical stress. At the micro-scale, this research examined how the extent and mode of facilitation and competition vary for different combinations of plant species along physical gradients. Both positive and negative relationships were spatially manifested to a greater degree on the low marsh than on the mid marsh. This insight extends our current knowledge of scale-dependent interactions beyond pioneer zones to higher zones. On the low marsh, different types of bivariate point pattern (i.e., clustered, random, and regular) were observed for different combinations of species even at similar spatial scales. This finding implies that it is difficult to generalize at which scales competition and facilitation occur. To conclude, this research stresses the need for a holistic approach in future investigations of salt marsh biogeography. For example, based on results of this current research, it would be meaningful to develop a comprehensive simulation model that incorporates salt marsh ecology, geomorphology, and hydrology observed across scales.

The Lower Keys marsh rabbit (LKMR, Sylvilagus palustris hefneri), a subspecies of marsh rabbit endemic to the Lower Keys, Florida, is threatened with extinction due to extensive coastal development of salt marsh habitats. LKMR recovery is limited by habitat loss and degradation from brush encroachment, predation by freeroaming cats (Felis catus) and raccoons (Procyon lotor), sea-level rise, and hurricanes. This study sought to determine local and landscape factors that influence LKMR metapopulation ecology and dynamics and to evaluate strategies for their recovery. I evaluated the influence of patch and landscape characteristics on LKMR densities, extinction, and colonization rates following Hurricane Wilma, and the response of LKMRs and salt marsh habitats to prescribed fire. I used estimates of population change based on annual monitoring data to validate vital rates, constructed a spatially explicit demographic model to evaluate various levels and spatial configurations of recovery scenarios implemented throughout the LKMRs range, and validated expected changes in parameter estimates using measures of habitat degradation and raccoon activity from known LKMR populations. I found LKMR densities were higher in patches with greater numbers of bunchgrasses and forbs and less edge and lower in patches with higher measures of raccoon activity. In response to a hurricane, I found the distance between LKMR patches and the coast had a negative influence on extinction probability; the distance between an extirpated and occupied LKMR patch had a negative influence on colonization probability and patch size had a positive influence. Adult LKMRs increased as woody cover <0.5 m decreased, herbaceous cover <0.5 m increased, and food availability increased in at least one site following prescribed fire. Model results indicated habitat management actions that improve carrying capacity of local rabbit populations and juvenile survival and control raccoon populations to increase rabbit reproductive rates are effective population recovery strategies. In total, my results provide a conservation planning tool that can be used to select recovery strategies and locations that will maximize benefits to LKMRs, thus improving their viability and recovery.

In this study, a reproducible spectrophotometric method was established and applied to measure reductive capacity of various nanomaterials. Reductive capacity had been implicated in the toxicity of nanomaterials, but a standardized measurement method had been lacking until this work. The reductive capacity of nanoparticles was defined as the mass of iron reduced from Fe3 to Fe2 by unit mass of nanoparticles, in an aqueous solution that initially contained ferric ions. To measure the reductive capacity, the nanomaterials were incubated in a ferric aqueous solution for 16 hours at 37 degrees C, and the reductive capacity of the nanoparticles was determined by measuring the amount of Fe3 reduced to Fe2 using a spectrophotometric method. The reagents 1,10-phenanthroline and hydroquinone were used as a Fe2 indicator and a reducing agent respectively for the assay. To standardize this method, various experiments were carried out. For the initial ferric solution, various Fe salts were tested, and Iron(III) sulfate was chosen as Fe salt for the standard method. The measured reductive capacity of nanoparticles was found to vary with the measurement conditions; the measured reductive capacity increased with increasing the Fe/nanoparticle ratio; the measured reductive capacity increased with incubation time and leveled off after 8 hours of incubation. For hydrophobic materials, the surfactant Tween-20 was added so that the particles could be wetted and suspended in the ferric aqueous solution. After incubation, the particles were removed from the solution by either filtration or centrifugation before applying the spectrophotometric method. In addition, optimal pH and minimum time to reach ultimate color intensity were also found. Carbon-based nanomaterials, standard reference material and metal oxides were measured for their reductive capacities with this method and characterized by transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), BET measurement and Raman spectroscopy. For some nanoparticles, the reductive capacity was measured for both the pristine form and the form treated by oxidization or grinding. All carbon-based nanomaterials, except for pristine C60, have a significant reductive capacity while reductive capacity of metal oxides is very low. And it was found that reductive capacity can be increased by surface functional groups or structural defects and reduced by oxidization or heating (graphitization). The reductive capacity of a material can play an important role in its toxicology by synergistic toxic effects in the presence of transition metal ions through the Fenton reaction. Moreover, even without transition metal ions, the ability of a material to donate electrons can be involved in toxicity mechanisms via generation of reactive oxygen species.

Feral swine (Sus scrofa domesticus) are spreading across North America at an alarming rate. Four Canadian provinces and 39 states within the continental United States now report standing populations of feral pigs. Estimates place the number of feral hogs in Texas >2M, accounting for more than half of the United States population. It is known that feral swine impact local ecology following establishment, with regard to shifts in local flora and fauna. The overall objective of this research was to investigate the role of feral swine in tick-borne pathogen transmission in Texas. The underpinning objectives were to establish host records for tick species parasitizing feral swine, determine the species assemblages associated with feral swine among different ecoregions of Texas, determine by immunoassay to which tick-borne bacteria feral pigs were being exposed, and detect the DNA of tick-borne bacteria by polymerase chain reaction assay in the event of poor or early immune response by the host. Feral pigs (N=432) were harvested from June 2008 to June 2010 using box and corral traps and by aerial gunning. Seven species of ticks, Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, and D. variabilis; and Ixodes scapularis, were collected. Immature stages of A. cajennense and A. americanum were collected as well. All classes of feral pigs, gender by age, were infested with ticks. Serum was collected through a multi-organizational effort from 2006 to 2010 and tested by ELISA for previous exposure to tick-borne pathogens in the genera Rickettsia and Ehrlichia (N=888) and Borrelia (N=849). Prevalence percentages by immunoassay were 27.59 percent, 13.18 percent and 2.12 percent for Rickettsia, Ehrlichia, and Borrelia, respectively. Samples positive by ELISA for exposure to Borrelia were further screened by Western Blot for exposure to Borrelia turicatae. The results were equivocal in most cases. Blood samples (N=233) were collected from 2008 to 2010 and analyzed by polymerase chain reaction for the detection of the DNA of these same three genera of bacteria. Two of the samples were positive by PCR for the presence of Borrelia DNA. Texas feral swine are serving as hosts for at least seven species of ticks and are interacting with tick-borne pathogen transmissions cycles in Texas.