Arsenic (As) and nitrate (NO3) are common contaminants in groundwater that are introduced through a variety of natural and anthropogenic sources. In this study we investigated the sources and distribution of As and NO3 in Goshen Valley, Utah, USA. Goshen Valley is a semi-arid alluvial basin that is impacted by geothermal waters, agriculture, urban development, and legacy mining. In this study we sampled surface water, springs, and wells to analyze concentrations of major ions, trace elements (As, B, Ba, Ca, Fe, K, Li, Mg, Mn, Mo, Pb, Si, Sr, Zn), and stable isotopes in water (δ18O and δD). A subset of samples were also analyzed for 87Sr/86Sr, δ34S, and tritium (3H). Major ion concentrations showed high spatial variability ranging from freshwater to brines, with the highest concentrations found in springs discharging from playa sediments. Likewise, the highest trace element concentrations, including As, were found in the playa-impacted springs. Elevated NO3 concentrations were found in springs and wells in agricultural areas of the valley. δ18O and δD values range from -0.90238 to -17.6 and -37.0891 to -134.5 respectively and represent that the valley contains old groundwater, evaporative surface water, and mixed water signatures in multiple wells. Tritium values range from 0.5 to 7.8 and further show the diversity of water in the valley by indicating old, young, and mixtures of old and young waters. Variations in 87Sr/86Sr were used to evaluate flowpaths of waters with elevated As. 87Sr/86Sr ratios suggest that the groundwater has interacted with a mixture of lithologic units including Tertiary volcanics, Paleozoic carbonates, and Quaternary alluvial/lacustrine fill. Correlations with As and playa affected springs indicate playa sediments as a major As source. The As found in wells has no apparent elemental correlations or spatial patterns and is likely due to the naturally occurring As in the valley alluvium and carbonate units. NO3 in the valley is concentrated in agricultural areas and is likely due to fertilizers, livestock, and alfalfa crops. Of all the potential contaminant sources, the data suggests that the major source of As is the saline playa soils and the major source of NO3 is agricultural activities in the valley.

Sexual violence has been a considered tragic yet inevitable part of most armed conflicts throughout history. Various connections have been made between natural resources and conflict-related sexual violence and this paper aims to explore this relationship further. This study uses theory on lootable natural resources and sexual violence to hypothesize that lootable natural resources, compared to unlootable, will affect the likelihood of sexual violence. The proposed hypothesis is that rebels who extort alluvial diamonds, a lootable resource, are more likely to engage in sexual violence. Using data from the SVAC and the RCD datasets, the hypothesis is tested through logistic regression. The empirical analysis show that the effect of diamond extortion is indeed statistically significant, which supports the hypothesis. These results contribute to finding possible predictors of conflict-related sexual violence, to help prevent further victims of this violence.

Northern boreal alluvial meadows are ecologically significant semi-natural ecosystems within the riparian zone. The effects of disturbance like flooding, grazing, and mowing have historically maintained high nutrient turnover and succession disruption that led to high biodiversity, leading to their inclusion in the Natura 2000 network. Today, alluvial meadows are threatened by human abandonment and river flow regulations, both of which provided necessary disturbances. This leads to encroachment by woody plants and a significant reduction in biodiversity. The purpose of this project was to investigate the hydrological conditions required for the long-term maintenance of floodplains of the regulated lower Dal River and how varying water levels affect the species distribution and various vegetation characteristics. This was done by examining plant data from 3 sites in an alluvial meadow in Bredforsen and datalogger water level data to calculate the duration of flooding of plots in a transect study. The effects of altitude, flooding durations, and frequencies on species richness, proportion of woody plants, and vegetation cover were examined. Flooding times showed the most significant effects on vegetation characteristics, while altitude and flooding frequencies differed greatly between sites, with variability explained being low for all explanatory variables. On one hand, this shows that that a lack of seasonal flooding has a negative effect on the alluvial meadow ecosystem and an increase in water flow would be beneficial. On the other hand, the low degree of explained variability implies that flooding solely is not the determining factor and other management methods are necessary to maintain the alluvial meadows.

The USDA Natural Resources Conservation Service (NRCS) implemented the Migratory Bird Habitat Initiative (MBHI) in summer 2010 to provide wetlands for waterbirds inland from the Deepwater Horizon Oil Spill. To evaluate MBHI and associated wetland management practices, I estimated seed and waterbird densities in MBHI and non-managed wetlands in the Mississippi Alluvial Valley (MAV) of Mississippi and Louisiana. Although not statistically different, wetlands enrolled in MBHI contained 1.26 and 1.53 times more seed biomass and seeds consumed by waterfowl than non-managed wetlands, respectively. I also detected 3 times more dabbling ducks and all ducks combined on MBHI wetlands. When I combined density data for all waterbird species, MBHI wetlands contained more than 2 times as many birds than control wetlands. Management via MBHI increased waterbird and potential food abundances, suggesting NRCS consider sustaining MBHI and provide financial incentives to landowners for management of wetlands in the MAV and United States.

The Mississippi Alluvial Valley (MAV) was dominated by extensive lowland forests, but during the 20th century most of the MAV was converted to agricultural, aquaculture, and other human uses. These land-use changes created stopover migration and wintering habitats for waterfowl, shorebirds and other waterbird species. Before landscape modification of the MAV, shorebirds likely migrated past the MAV to wetlands along the northern Gulf of Mexico (NGoM). In 2010, the Deepwater Horizon oil spill impacted coastal marshes of the NGoM. The USDA Natural Resources Conservation Service implemented the Migratory Bird Habitat Initiative (MBHI) to provide waterbirds with wetlands inland of oil-impacted areas. My objectives were to 1) statistically model the waterbird community on wetlands in the MAV and NGoM, 2) estimate relative abundance of shorebird and other waterbirds in idled aquaculture ponds enrolled in MBHI and associated wetlands in the MAV and NGoM, and 3) collect shorebird feathers and blood for stable isotope analysis (13C/12C, 15N/14N) to assess foraging niches and potential migratory connectivity between MAV and NGoM habitats during 2012 – 2013. Consequently, autumns of these years were under a drought, extensively wet from Hurricane Isaac, and exhibited average precipitation in the post-hurricane recovery period which may have had an effect on waterbird assemblages differing by year, month, twice-monthly survey period, latitude, region, state, site, and water depth index. Latitude shifted north and water depth was narrowest when abundant wet habitat existed on the landscape in 2012. Bird abundances were greatest in 2011 and never recovered to these levels in 2012 or 2013, which may have reflected effects of drought concentrating birds on remaining wetlands in 2011 and subsequent to the hurricane. Stable isotope analysis of blood indicated spatial segregation of shorebird species. Neither blood nor feather carbon and nitrogen values revealed definitive linkage of sites between the MAV and NGoM. Shallow water habitat inland may be a limiting resource during migration for waterbirds, especially in drought years when other wetlands may have been limited. Thus, provision of wetlands (mudflat – 15 cm) by MBHI and other conservation strategies across the landscape may allow waterbirds access to needed resources during migration.

Interest in, and rates of, wetland restoration have increased over the past several decades. However, despite proliferations of restored wetlands across the landscape, the structural and functional restoration success of these systems is unclear. Thus, understanding factors and processes that influence wetland characteristics is of considerable interest. This study focuses on herbaceous wetlands in the Mississippi River Alluvial Valley (MAV), a largely agricultural region interspersed with restored and naturally occurring wetlands. Chapter I is an introduction and provides a background to wetlands, wetland ecology, and the current state of wetland restoration in the United States. Chapter II focuses on factors which affect seedling density and similarities between standing vegetation, germinated seedlings, and early successional stage assemblages. Seedling density was heavily influenced by hydrology while richness and diversity were similar between restored and non-managed wetlands. Landscape-level factors affected seedling density, while germinated seedlings did not reflect standing vegetation in MAV wetlands. In Chapter III, I examine the impact of agricultural stressors on wetland plant assemblage development. Resulting assemblages showed strong fidelity to wetland soil site of origin while richness and diversity were negatively affected by elevated stressor levels. In Chapter IV, I compare characteristics between non-managed and restored wetlands in the MAV. These wetlands differed hydrologically, had different levels of soil organic matter, were dissimilar in plant assemblage composition, and varied by surrounding land use/cover. Finally, Chapter V is a discussion of the results and places this work within a larger context.

No evaluations of plant and wildlife communities in Wetlands Reserve Program wetlands have been conducted in the Mississippi Alluvial Valley. Therefore, I evaluated active and passive moist-soil management (MTYPE) and early and late draw-down on plant communities, waterbird use, and water quality on 18 WRP lands, Mississippi, 2007-2009. Active-early sites had greater waterfowl Vegetative Forage Quality (VFQI), percentage occurrence of grass, plant diversity, and structural composition than passively managed sites (P < 0.10). I modeled variation in densities of wintering waterbirds; the best model included VFQI*MTYPE and decreased % woody vegetation (wi ≥ 0.79). Additionally, waterbird densities varied positively with active-late management (R2 ≤ 0.27), as did duck species richness with flooded area (R2 = 0.66). I compared water quality parameters among managed wetlands and drainage ditches but did not detect differences due to variability. Therefore, wetland restoration on WRP lands should focus on active management and maximizing wetland area.

Oxbow lakes are highly productive waterbodies that host multiple life stages of many freshwater aquatic species. Oxbow lakes also provide habitat to Silver Carp (Hypophthalmichthys molitrix), which has enabled populations to grow and expand within the United States. Silver Carp are undesirable because they can compete for resources with native fishes. My goal was to identify patterns of distribution and dispersion of Silver Carp in Moon Lake, Mississippi, to assist and inform precise harvesting of fish. I implanted thirty-five adult Silver Carp with acoustic tags that I released into Moon Lake. I observed that Silver Carp were disproportionately found in locations where water depths ranged from 2.0-5.9 m during all seasons, despite the availability of locations with shallower and deeper water. Silver Carp did aggregate in the wintertime (December-February) in comparison to all other seasons. This information about depth distributions and seasonal aggregations can inform removal programs.

Low grade rip rap weirs installed in agricultural surface drainage ditches manage downstream eutrophication by slowing water flow, allowing sediments time to settle out of the water column and phosphorus (P) to sorb to soil. A laboratory experiment was conducted in microcosm chambers to simulate increased hydraulic residence time caused by weirs and two field studies were conducted to compare experimental data with field data and determine sediment deposition rates. One field study monitored weirs monthly after installation and the other measured weirs of varying ages. Weirs retained significantly more water and sediment than controls. Longer inundation times led to abiotic factors known to release P during hydrologic flux, but did not translate to reduced P storage. By converting intermittently inundated sediments into more consistently saturated sediments, weirs function as a viable conservation practice for about a year until temporary P retention mechanisms and sediment retention capacities are reached.

Estimates of abundance are critical to manage and conserve waterfowl and their habitats. Most surveys of wintering waterfowl do not use probability sampling; therefore, development of more rigorous methods is needed. In response, I designed and evaluated an aerial transect survey to estimate abundance of wintering ducks in western Mississippi during winters 2002?2004. I designed a probability-based survey using stratified random and unequal probability sampling of fixed-width transects. To correct for visibility bias inherent in aerial surveys, I conducted an experiment to model bias and incorporated correction factors into estimation procedures to produce adjusted estimates. Bias-corrected estimates were most accurate. Precision of abundance estimates of total ducks met a priori goals (CV ≤ 15%) in 10 of 14 surveys. Based on a simulation study, the implemented survey design provided the most precise estimates, yet certain refinements remained possible. I also illustrated potential applications of survey results in the context of conservation and management of wintering waterfowl populations and habitats. I described patterns of abundance within and among winters, including a comparison with surveys conducted during winters 1988?1990 that revealed mallard abundance decreased 65% from the late 1980s. I developed a method to illustrate population abundance spatially for scientific and public education. I attempted to explain temporal variation in abundance estimates relative to variables potentially representing hypotheses explaining regional distributions of ducks. I concluded the data provided stronger support for factors related to energy conservation by ducks than factors related to energy acquisition. Finally, I determined associations between duck distributions and habitat and landscape features in accordance with the habitat-complex conceptual model. Landscapes with greater interspersion and diversity of wetlands attracted increased numbers of ducks, a though other factors such as wetland area also were important. I concluded that this study advanced methodologies to survey wintering waterfowl. Although improvements were warranted, I recommend this survey design for continued monitoring of wintering ducks in western Mississippi. Furthermore, I suggest habitat management on public and private lands should include complexes of seasonally flooded cropland, moist-soil, forested, and permanent wetlands to potentially increase wintering duck numbers in western Mississippi.