Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Geography." Includes bibliographical references (p. 38-50).

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2004. / Title from title page screen (viewed Sept. 20, 2004). Thesis advisor: Wayne K. Clatterbuck. Document formatted into pages (xiii, 174 p. : ill.). Vita. Includes bibliographical references (p. 144-152).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 99-103). Also available on the World Wide Web.

Oomycetes are eukaryotic fungus-like microorganisms that are known to be pathogenic to plants and animals, causing both ecological and economic damage. Animal pathogenic oomycetes, such as Saprolegnia species are destructive pathogens to many aquatic organisms and are found in most parts of the world. Phytophthora species cause a number of plant diseases. Pythium are less understood as many of these species are saprotrophs which are not thought to be pathogenic. Oomycete research has focussed mainly towards the characterisation and control of pathogenic species with very little information on the ecology of Oomycetes. In this thesis, oomycete species were isolated from water samples collected from rivers in Scotland and Northern England. Baiting and water filtration were used to compare the reliability of both methods, and nested PCR was used to compare the number and types of species obtained in comparison to conventional culturing methodologies. The results suggest that water filtration provided a fast, reliable method for isolating abundant, hardier species such as Pythium undulatum, Saprolegnia diclina, Saprolegnia delica, and Saprolegnia ferax. Water chemistry, surrounding land use, seasonality and land elevation were found to be important factors in Oomycete diversity. Nested PCR of oomycetes directly from filters to obtain target DNA from organisms which are more difficult to culture or less numerous proved to be useful for some species, but will need more refinement of primer and methodologies to obtain species of interest. Sampling of the rivers resulted in the isolation of three new Pythium spp. isolated from the Rivers Spey and Dochart in Scotland. Phylogenetic analysis, infection studies, growth rates and microscopy were used to characterise these three species.

Increased salinization of inland freshwater resources is present on a global scale, but is pro- gressing rapidly in the densely populated Mid-Atlantic United States. This phenomenon threatens aquatic health, ecosystem services and functionality, and can alter the percep- tion of potable drinking water. The Occoquan watershed, located in Northern Virginia has experienced rapid urbanization across recent decades and is now confronted with rising salinization. Various stakeholders in the area have focused efforts to quantify the drivers of salinization in order to take corrective action to preserve this resource. To aid these efforts, urbanization's relationship with in-stream salinity was analyzed, where its exerted influence was found to be dependent upon overland hydrologic flowpaths which connect urban areas to stream networks. The analysis was then broadened to Multiple Linear Regression models of urban and climatological drivers to statistically quantify each driver's relative influence on in-stream salinity. The models demonstrated that urbanization is the primary driver, where rainfall and roadway deicer application were also found to be significant. The model was then used to predict the magnitude of salinization in the Occoquan watershed to a time horizon of 2040 based on expected population growth as well as two anticipated climate scenarios. Finally, the analytical framework produced in this research was generated with scalability in mind, such that it can potentially be utilized as a watershed-scale screening tool accross the Mid-Atlantic, to inform proactive, regionally appropriate management decisions. / Master of Science / Increased salinization of inland freshwater resources is present on a global scale, but is progressing rapidly in the densely populated Mid-Atlantic United States. Driven by the engineered systems that define our modern world, this phenomenon threatens aquatic health, ecosystem services and functionality, and can alter the perception of potable drinking water. The Occoquan watershed, located in Northern Virginia has experienced rapid urbanization across recent decades and is now confronted with rising salinization. Various stakeholders in the area have focused efforts to quantify the drivers of salinization in order to take corrective action to preserve this resource. The analyses completed in this body of work act to model and statistically analyze the drivers which foster salinization in the Occoquan. The analyses demonstrated that while climatological factors drive salinity in the Occoquan, urbanization is the primary driver, where its exerted influence is dependent upon overland hydrologic flowpaths which connect urban areas to stream networks. Further analyses were completed to project salinization to a time horizon of 2040 based on expected population growth as well as two anticipated climate scenarios to predict the magnitude of salinization in the Occoquan watershed in decades to come. These results indicated that anticipated levels of in-stream salinity will increase across most sampling stations in coming years. Finally, the analytical framework produced in this research was generated with scalability in mind, such that it can potentially be utilized as a watershed-scale screening tool accross the Mid-Atlantic, to inform proactive, regionally appropriate management decisions.

Understanding spatiotemporal variation in net primary productivity (NPP) continues to be of fundamental importance to basic ecology and to applied conservation and management efforts for human well-being. Diversity is an important driver of NPP variation, but its effect is variable depending on ecosystem context and spatial scale as well as more closely linked to functional traits. Explicitly considering processes of trait-based community assembly and maintenance at relevant scales at which they occur can potentially resolve some of this variation. In my thesis, I address this gap by considering various processes that structure and maintain diversity in communities and analyze NPP as an outcome of these processes. I examine processes in high diversity tropical forests, relatively less explored in the context of biodiversity-ecosystem functioning. In Chapter 1, through a manipulated experiment, I show that diversity effect on biomass gain in seedling communities is modulated by light. This interactive effect holds across different functional groups that are known to respond uniquely to light. In Chapter 2, I expand the spatial scale of inquiry to community assembly processes that maintain diversity at regional spatial scales – dispersal and competition, akin to island biogeographic contexts. Through simulations, I show that dispersal and competition acting on correlated traits explain a range of variation in BEF curves observed in nature. Finally, in Chapter 3, expanding the focus of inquiry to include human aspects, I consider the impact of a biodiversity-driven human intervention, protected areas, in maintaining NPP. I show that at the landscape scale, mean annual NPP and temporal stability are both influenced by protection status, but the effectiveness of protection is contingent on environmental factors. Taken together, my thesis suggests that understanding the combined drivers of diversity and NPP can improve predictions for spatiotemporal variation of this ecosystem function. Further inquiry integrating diversity-gradients at multiple scales can improve process-based understanding of the effect of biodiversity on ecosystem functioning.

Background: Venomous snakebite and its effects are a source of fear for people living in southern Nepal. As a result, people have developed a negative attitude towards snakes, which can lead to human-snake conflicts that result in killing of snakes. Attempting to kill snakes increases the risk of snakebite, and actual killing of snakes contributes to loss of biodiversity. Currently, snake populations in southern Nepal are thought to be declining, but more research is needed to evaluate the conservation status of snakes. Therefore, we assessed attitudes, knowledge, and awareness of snakes and snakebite by Chitwan National Park's (CNP) buffer zone (BZ) inhabitants in an effort to better understand challenges to snake conservation and snakebite management. The results of this study have the potential to promote biodiversity conservation and increase human health in southern Nepal and beyond. Methods: We carried out face-to-face interviews of 150 randomly selected CNP BZ inhabitants, adopting a cross-sectional mixed research design and structured and semi-structured questionnaires from January-February 2013. Results: Results indicated that 43 % of respondents disliked snakes, 49 % would exterminate all venomous snakes, and 86 % feared snakes. Farmers were the most negative and teachers were the most ambivalent towards snakes. Respondents were generally unable to identify different snake species, and were almost completely unaware of the need of conserve snakes and how to prevent snakebites. Belief in a snake god, and the ability of snakes to absorb poisonous gases from the atmosphere were among many superstitions that appeared to predispose negativity towards snakes of BZ residents. Conclusion: People with predisposed negativity towards snakes were not proponents of snake conservation. Fear, negativity, ambivalence towards, and ignorance about, snakes and the need for snake conservation were strong indicators of the propensity to harm or kill snakes. It seems that if wanton killing of snakes continues, local snake populations will decline, and rare and endangered snake species may even become locally extirpated. Moreover, inappropriate perception and knowledge about snakes and snakebites may put BZ people at increased risk of venomous snakebite. Therefore, intensive, pragmatic educational efforts focused on natural history and ecology of snakes and prevention of snakebite should be undertaken in communities and at schools and universities.

Global demand for agricultural products is an increasingly important driver of deforestation in the Amazon Basin. This dissertation examines the consequences of agricultural expansion for stream ecosystems in the southern Amazon's agricultural frontier. At regional scales, the removal of watershed forest cover is known to change the energy balance and influence hydro-climatic cycling by altering stream flow, regional rainfall patterns, and land surface temperatures. At the landscape scale, these physical changes may be further exacerbated by land management practices that lead to the degradation of riparian forest buffers; decreases in connectivity; changes in the amount of light, nutrient, and sediment inputs; and decreases in water quality. Together, land use and management influence the quality and distribution of aquatic habitats within stream networks, potentially decreasing stream biotic integrity and resilience to further disturbances. Brazil's Mato Grosso state is one of the most actively expanding agricultural frontiers in the world and represents an ideal case study for examining the linkages among tropical deforestation, agricultural expansion, and the conservation of freshwater ecosystems. Mato Grosso accounted for 40% of deforestation in the Brazilian Amazon during the early 2000s - primarily due to the expansion of soybeans and cattle ranching. Deforestation rates have since dropped throughout the Amazon, but there is a lack of spatially explicit information about the land use transitions accompanying this decline. To address this gap, I combined government data on deforestation and production with the MODIS satellite time series to quantify the spatial-temporal dynamics of land use change in the region. Although agricultural expansion during this period slowed with declining commodity prices, the decline in deforestation is partly explained by a shift from soybean expansion into forests (26% of expansion from 2001-2005) to expansion into already cleared pasture lands (9% of expansion form 2006-2010). Beyond documenting these trends, the resulting dataset is a critical first step in evaluating the influence of land use and land use history on freshwater ecosystems at multiple scales. In the headwaters region of the Xingu River Basin, the proportion of small watersheds (microbasins) dominated by agriculture (>60% of area) increased from 20 to 40% from 2001 to 2010. At the same time, the stream network became increasingly fragmented by the removal of riparian forest buffers and installation of farm impoundments. I used high resolution satellite data (ASTER) to produce the first landscape-level documentation of farm impoundments in the region, mapping approximately 10,000 impoundments (one per 7.6 km of stream length) in 2007. At the catchment scale, I collected field data in 12 headwater streams to examine the effect of land management on instream water quality. Watershed forest cover (from MODIS), the density of impoundments (from ASTER), and the percent forest in upstream riparian buffers (from Landsat) were all associated with substantial increases in stream temperature. These increases in fragmentation and water temperature may have large cumulative effects on the stream network and reduce the ability of downstream protected areas to conserve freshwater resources. At the scale of the Amazon Basin, my analysis indicates that 30% of indigenous lands and protected areas are highly vulnerable to future reductions in hydrologic connectivity, simply because of their location within their watersheds. These impacts could be substantially mitigated through enforcement of existing legislation to protect riparian buffers and new regulations to limit the number of impoundments in emerging agricultural landscapes.

The high northern latitudes of North America are undergoing rapid climatic change with acute impacts to the ecosystems in which millions of songbirds breed each year. The goal of this dissertation is to improve understanding of how concurrent and interacting changes in environmental and land surface conditions influence annual movements and habitat selections of long distance migratory birds who must navigate the mosaic of changing North American ecosystems. Chapter 1 presents novel automated bioacoustic methods for estimating arrival dates of the songbird community to their arctic breeding grounds. Automated acoustic networks could vastly expand the spatiotemporal coverage of wildlife observations. However, the enormous datasets that autonomous recorders typically generate demand automated analyses that remain largely undeveloped. Chapter 1 demonstrates novel machine learning and signal processing techniques for estimating songbird community arrival dates near Toolik Field Station which agreed well with traditional survey estimates and were strongly related to the landscape’s snow free dates. Daily variations in vocal activity were more strongly influenced by environmental conditions prior to egg-laying dates. The success of the approaches presented in Chapter 1 indicate that variation in songbird migratory arrival can be detected autonomously. Widespread deployment of this advance could provide avian monitoring on a scale large enough to enable global-scale understanding of how climate change influences migratory timing of avian species. Chapter 2 examines potential future changes in habitat suitability for for two songbirds breeding throughout North America’s high northern latitudes – a tundra-nesting species (Lapland Longspurs (Calcarius lapponicus)) and a shrub-nesting species (White-crowned Sparrows (Zonotrichia leucophyrs)). By the late 21st century, models based on both climate and vegetation projected habitat suitability for Lapland Longspurs decreased across nearly all of the study domain (54-96%), while that for White-crowned Sparrows decreased in 69% of North America’s high northern latitudes. For both species, currently unsuitable habitats in northern Canada and Alaska are projected to provide suitable breeding habitat in the future. In contrast, models based solely on climate showed more drastic declines in habitat suitability for both species (Lapland Longspur, ~100% and White-crowned Sparrow ~80%). This discrepancy between model projections demonstrates that the future availability of suitable songbird breeding habitat for both species will be strongly dependent on how both the vegetation and climate– as opposed to climate alone - of northern ecosystems respond to ongoing climate change. Chapter 3 investigates the environmental and ecological drivers of migratory movements of songbirds breeding at high northern latitudes. For North America alone, there is overwhelming evidence of major shifts in seasonality of meteorological conditions, snow cover, and vegetation phenology. Few studies have focused on how this suite of changes impacts long distance migratory species that annually navigate throughout the spatially and temporally dynamic mosaic of ecosystems because of technological constraints in animal tracking. However, recent advances in GPS technology have generated units small enough to be placed on songbird species. In 2016-2018 a total of 55 American robins (Turdus migratorius) were tracked during their spring migration through the Canadian boreal forest en route to their breeding grounds. We found a significant trend towards earlier arrival of robins to the Canadian boreal forest over the past quarter-century, consistent with advances in spring environmental conditions. Robin stopover timing at our tagging site was delayed in response to later seasonal snowmelt, but triggered by adverse environmental conditions. Individuals breeding in regions with shorter snow-free seasons moved faster than individuals breeding in areas with longer snow-free seasons and selected locations with less favorable environmental conditions. Overall, arrival timing to breeding grounds was negatively related to snow depth and positively related to snowmelt timing. Migratory movements and timing of American robins are highly tied to seasonal environmental dynamics en route to their breeding grounds. Our findings present a unique, mechanistic understanding of how migratory birds navigate highly dynamic ecosystems. In light of rapid global change, the use of multi-disciplinary, spatially explicit approaches similar to the ones used in this dissertation will be critical for understanding how avian taxa breeding at high northern latitudes may respond to ongoing and future change. This is important for investigating both regional and global impacts because species breeding in arctic-boreal zones perform key ecosystem services around the globe.

Thesis (Ph.D. (Zoology)) --University of Limpopo (Turfloop Campus), 2011 / South Africa's water resources are limited and scarce in global terms, due to the fact that the country's climate varies from desert to semi-desert in the west to sub-humid along the coastal area. The country is also expected to experience further variability in rainfall, reduced precipitation and increased evaporation as a result of climate change. At the projected population growth and economic development rates, it is unlikely that the projected demand on water resources in South Africa will be sustainable. An additional concern is the declining water quality due to domestic, mining and industrial pollution, and eutrophication as well as salinisation due to agricultural pollution. Thus, aquatic ecosystems must be protected, monitored and managed to ensure sustainable resource use. The aim of the study was to evaluate and compare possible environmental deterioration by analysing fish health and parasite diversity in three dams within the Limpopo and Olifants River Systems by using the fish Health Assessment Index (HAI) and the Inverted Parasite Index (IPI). The intention of the study was to substantiate the theories behind the HAI and IPI in a bid to augment strategies to manage water quality, fish health and aquatic biodiversity. Seasonal surveys were carried out between April 2008 and April 2010 at three localities. The Luphephe-Nwanedi Dams are in a Nature Reserve located in a rural catchment, the Flag Boshielo Dam in an industrualised and mining catchment whereas the Return Water Dam is located on a platinum mining premise. Clarias gariepinus (Burchell, 1822) and Oreochromis mossambicus (Peters, 1852) were collected with the aid of gill nets and used as indicator fish species. Fish were examined for external parasites after which they were weighed and measured. Blood was drawn and skin smears were made. The skin smears were examined with a dissecting microscope for the presence of parasites. Fish were killed, dissected and then examined as prescribed in the fish HAI. From the ecto- and endoparasite data collected, infection statistics and ecological parameters were calculated. The HAI values were calculated for each fish species at each sampling site. To verify the results of the HAI, water quality was included in the studyThe nutrients and mining related pollutants of the three dams differed to a great extent and showed a similar increasing trend in the order: Luphephe-Nwanedi Dams < Flag Boshielo Dam < Return water Dam. Our results were consistent with previous work describing Luphephe-Nwanedi Dams as essentially unimpacted and Flag Boshielo Dam as impacted with a combination of mining and agricultural effluents. The results have shown that the Return Water Dam is an extremely polluted site with high levels of nutrients and metals. Fish health of both species responded similarly to polluted sites although mean population HAI results showed that C. gariepinus was more affected in terms of haematocrit necropsy-related alterations. The top six metrics that correlated most to fish health scores were nearly the same for both species (i.e. haematocrit values, inverted ectoparasite index, condition of the kidney, liver, gills and skin). The parasite community of C. gariepinus comprised 19 metazoan species. Seventeen parasite species were recovered from fish sampled from Luphephe-Nwanedi Dams compared to 11 at Flag Boshielo Dam and four at the Return Water Dam. The parasite community of O. mossambicus comprised 20 metazoan species. A total of 19 species, 17 species, and 4 species of metazoan parasites from O. mossambicus were obtained from Luphephe-Nwanedi Dams, Flag Boshielo Dam and the Return Water Dam, respectively. In both fish species, the Shannon Wiener Index, the inverse Simpson Index, equitability and the number of metazoan parasite individuals were highest in fish from Luphephe-Nwanedi Dams. The results of this study emphasized the negative impacts of urbanization, agricultural and mining activities on the environment. The fish hosts collected in the mining premise supported the poorest and least diverse parasite communities of all sampled sites, with virtual depletion of both heteroxenous and monoxenous species. The Return Water Dam may therefore be regarded as a simulation model for a severely environmentally deteriorated, impoverished habitat, in which all or part of the intermediate hosts have been depleted, enabling the survival of hardy parasite species only. Further studies should address the identification of parasite life stages that are more sensitive to pollutants / The National Research Foundation,the Flemish Interuniversity Council(VLIR-UOS),and the Division for Research Administration and Development,University of Limpopo