I evaluated diet and food selection of 5 species of spring-migrating female waterfowl including 3 dabbling ducks (Blue-winged teal, Anas discors, Mallard, Anas platyrhynchos, Gadwall, Anas strepera) and 2 diving ducks (Lesser Scaup, Aythya affinis, and Ring-necked duck, Aythya collaris). Diet was evaluated with regards to the proportion of invertebrates and seeds consumed, and compared to forage availability data collected in habitats available to them at 6 study locations throughout the Upper Mississippi River and Great Lakes Region. I found latitude (i.e., stage of migration), longitude, food availability, and date all influenced the diet of spring migrating waterfowl, with some factors having a stronger influence than others. I observed differing diet trends with regard to foraging guild (e.g., dabbling and diving ducks), as each foraging guild was represented by 1 species that was heavily dependant on invertebrates (dabbling duck - Blue-winged teal; diving duck - Lesser scaup) and 1 species that was heavily dependant on seeds (dabbling duck - Mallard; diving duck - Ring-necked duck). The proportion of invertebrate foods in the diet increased throughout spring for all species of waterfowl, suggesting the importance of invertebrate food sources during spring staging. Data from this study provides valuable information to habitat managers and conservationists wishing to improve spring habitat conditions for migrating waterfowl, which likely influences waterfowl productivity.

This study utilized a new database of levee failures along 685 km of the Middle and Lower Mississippi River from St. Louis, MO to Memphis, TN during the past 120 years. The goals of this investigation were to: 1) identify the relative importance of geologic and geomorphic factors that have led to levee failures through the past century along the Mississippi River and 2) measure levee crest elevations to determine if they have increased or decreased between 1998 and 2007 and if they are built to the proper design grade elevation. Logistic regression analysis was utilized to examine selected site characteristics at each levee failure location. These site characteristics (levee failure parameters) included: 1) levee underlain by previous channel fill, 2) presence/absence of borrow pit, 3) location of failure on a meander bend, 4) width of channel, 5) width of floodway, 6) constriction-over-time factor, 7) land-cover type, 8) width of vegetative buffer, 9) sinuosity of channel, 10) intensity of dredging, and 11) presence/absence of bank revetment. Each of these parameters was evaluated using geologic maps, soil survey data, Digital Elevation Models (DEMs), historic river maps, and dredging reports (Winkley, 1977; Pinter et al., 2004). Two models were created for each river reach. The first model for both reaches used a 95% significance threshold, while the second model for the MMR used a 80% significance threshold, and the second model for the LMR used a 90% significance threshold. The first model for the Middle Mississippi River (MMR) identified only the presence/absence of channel fills to predict levee failure as significant, had an R² value of 0.178, a p-value of 0.002, and a percentage accuracy of 68.6%. The second model for the MMR identified the following variables as significant: presence/absence of channel fills to predict levee failure, location of failure on a meander bend, channel width, land-cover type, and intensity of dredging. This model had an R2 value of 0.408, p-value of 0.002, and a percentage accuracy of 74.3%. The 95% model for the Lower Mississippi River (LMR) identified location of failure on a meander bend, land-cover type, constriction-over-time factor, and sinuosity of the channel as significant. This model had an R2 value of 0.326, p-value of 0.003, and a percentage accuracy of 69.5%. The 90% LMR model identified the following variables as significant: the presence/absence of borrow pits, location of failure on meander bend, channel width, land-cover type, constriction-over-time factor, vegetative buffer width, channel sinuosity, and presence/absence of bank revetment. This model had an R2 value of 0.385, p-value of 0.006, and a percentage accuracy of 72.0%. The MMR and LMR models with the 95% significance threshold had no predictors in common because of differences between the two river reaches or possibly because of the small sample size. However, the expanded MMR and LMR models shared three predictors (i.e., meander location, channel width, and land cover type). The second portion of this project used post-processed dual-frequency GPS surveying to measure levee elevations between St. Louis, MO and Cairo, IL. These elevations were compared to the 50-year design flood grade elevations and to a 1998 DEM to identify areas of levee heightening, levee degradation and/or subsidence, and locations of past levee crevasses. This surveying revealed areas that, between 1998 and 2007, were raised up to ~1.5 meters and other areas that degraded or subsided up to ~1.0 meter. Also, the locations of five recent levee crevasses were investigated, showing local increases or decreases at those points. The importance of levee road construction type was identified through many sharp increases or decreases at the transition between road types. Overall, this project showed promising implications for the determination of levee failure susceptibility and proper levee elevation heights using logistic regression analysis and kinematic GPS surveying. The logistic regression models predicted the potential for levee failure based on local site characteristics of levees between St. Louis, MO and Memphis, TN. The high-precision kinematic GPS surveying illustrated levee elevations along the MMR to a high degree of accuracy, allowing for the rapid and efficient identification of areas that do not correspond to the proper design flood grade elevation.

Thecamoebian tests from recent lacustrine sediments have been shown to be a useful proxy to study environmental changes such as land-use changes, pollution, and climate shifts. In this study, the usefulness of thecamoebians as an environmental proxy for the Middle Mississippi River (MMR) floodplain is explored. Sediment cores and surface samples were collected from two sites in Alexander County, IL: Southern Illinois University's (SIU) MMR Wetland Field Station near East Cape Girardeau, IL and Horseshoe Lake, a dammed oxbow managed by the IL Department of Natural Resources (DNR), near Olive Branch, IL. These sites represent different floodplain environments, management histories, and flooding patterns. The thecamoebian populations were expected to reflect these differences while also responding to regional signals associated with development, agriculture, and climate. Cores were subsampled at a 5cm interval and all samples were sieved with 150μm and 45μm screens to retain thecamoebian tests. Sieved sediment was examined under a microscope and at least 100 tests were identified in each sample. Pre- and post-land clearing assemblages are recognized at each site, primarily by the increased abundance of the eutrophic-indicating species Cucurbitella tricuspis. Additionally, grab samples collected from the wetlands site during the spring indicate that the site may be influenced by road salt runoff in addition to agricultural activity. These results suggest that thecamoebians are a useful land-use change proxy and more research is needed to better understand the environmental conditions influencing assemblages.

Accurately measuring denitrification in stochastic floodplains, particularly the leveed and unleveed reaches of the Mississippi River basin, requires innovative experiments. To replicate hydraulic variability ranging from overland flooding to groundwater exfiltration in floodplain wetlands, I incubated sediment cores collected from four field sites across the Dogtooth Bend of the middle Mississippi River; pairing novel deep injection (Graphic Abstract Fig. A, left) with traditional surface delivery (Graphic Abstract Fig. A, right) of both oxic and anoxic Mississippi River water. In sandy sediments with unconstrained flux of nutrients, denitrification more than doubled across a range from 192 to 429 mg N m-2 day-1 in a linear anoxic-injection hierarchy of anoxic deep > anoxic surface > oxic deep > oxic surface treatments. In contrast, for incubations in diffusion-limited clay sediments, injection type made no difference; however, in anoxic conditions denitrification rates were as high as 435 mg N m-2 day-1 compared to oxic incubations at 187 mg N m-2 day-1. This methodology reveals the magnitude of diverse denitrification rates spanning different hydrologic conditions (Abstract Fig. B) and the mediation of denitrification by sediment type. These findings provide quantified bounds to inform resource management decisions regarding what areas should be selected for protection or hydrologic reconnection to best facilitate nutrient processing services like denitrification under varying hydrologic conditions.

In rivers that shift in their natural or modified physical structure, it is expected that organisms alter their resource use with the shifts in physical changes. The Upper Mississippi River System (UMRS) is a modified river basin and stark contrasts in both the physical structure of habitat types and biological structure in the types of organisms present exist spatially. The upper reaches of the basin contain more complex habitat types than the lower reaches which suggests resource use of fishes likely differs at least between upper and lower reaches. To date, the resource use of some commercially important, invasive, and imperiled species has been studied. However, little information regarding resource use exists for most native fishes. Understanding resource use and how it differs across time and space would benefit managers of the UMRS as programs are underway to restore and manage the system. To determine how resource use of native fishes differs spatially and temporally in the UMRS, I quantified resource use of ten native fishes across six reaches of the UMRS using multiple techniques. At the largest spatial and temporal scale, I quantified the natal origins of six prey and two predatory fishes using trace element analysis. At a seasonal scale, I quantified the collective resource use of eight species using carbon and nitrogen isotopes to compare isotopic niche space, niche overlap, and community metrics. At the shortest scale, I quantified the diets of two predatory species that are thought to compete with one another. Both large scale similarities and nuances in resource use existed in the UMRS depending on the spatial and temporal contexts. At the longest scale, fishes consistently used network connectivity as tributaries and other mainstem river reaches contributed recruits to the mainstem river. However, the percentage of individuals resulting from network connectivity and the specific rivers that lent the recruits differed among species and reaches. Particularly, large tributaries like the Minnesota and Missouri rivers contributed relatively high numbers of recruits to nearby reaches compared to other tributaries, and the most downstream reaches had the greatest contributions from network connectivity. Prey fishes recruited more often from tributaries than predators whereas consumed prey and prey collected directly from the UMRS had similar origins which were consistent across years. At a seasonal scale, breadth of resource use of individual species and the assemblage and some community metrics increased whereas overlap decreased moving downstream in the UMRS. This shift in resource use metrics coincides with shifts in the physical structure of the system. At the shortest scale, diet compositions of the two predators were similar to one another and spatially among upper reaches in the UMRS. These two predators likely coexist in part due to diet plasticity and prey size allocations that differ between species. Additionally, the relative physical homogeneity of the upper reaches of the UMRS may have led to the spatial similarity in prey use. Together, these results suggest the physical structure of the system impacted the resource use of fishes, where trophic niches and use of network connectivity shifted with the shift in physical structure of the Mississippi River. At a minimum, spatial gradients in isotopic niches and percentage of individuals coming from network connectivity suggest the resource use of fishes in downstream reaches at seasonal and life-long scales differs from the upstream reaches within this system. These differences could stem from longitudinal or functional process zone shifts in the physical structure which cannot be determined given these data. In the context of management of the system, fishes use network connectivity to at least some degree across all species and sampling reaches, indicating that the connectivity in the system should at least be maintained if not improved. Additionally, fish move among reaches (i.e., through lock and dams) and tributaries, which highlights the need for interjurisdictional management not just in the UMRS but in nearby tributary systems like the Minnesota and Missouri River where fish originated.

The lower Mississippi River alluvial valley (LMRAV) in northwestern Mississippi is characterized by a flat landscape and predominantly agricultural land use. The fluctuations in surface heat flux throughout the crop cycle due to land cover modifications are thought to have an impact on the regional weather. This research analyzes changes in convective patterns over the LMRAV based on the rapid variations in land cover as a result of the seasonal harvest cycle. Focusing on synoptically weak days between 2012-2016, data from the GOES 13-15 satellite visible imagers were used due to their 1-km spatial resolution and ability to distinguish lower clouds over a warm surface. By comparing the spatial and temporal patterns of convective clouds, the study confirmed that convective patterns do change based on land cover evolution resulting from the harvest cycle. These changes were likely a result of low-level thermal and moisture changes resulting from variations in evapotranspiration.

The Lower Mississippi Alluvial Valley (LMAV) was once the largest floodplain in the United States. Flooding regimes in the LMAV have strong impacts on the soil biogeochemical processes, nutrient cycling, forest species distribution, agricultural production, and wildlife habitat. This study characterized the LMAV flooding regimes using the 8-day-composite Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance product from 2001 - 2018. The results showed significant spatial variations in the annual flooding duration in the LMAV, and the flooding area showed remarkable seasonal variations in the northern and central LMAV with the peak flooding area in winter and early spring. Digital Elevation Model (DEM) and slope were identified as the two major factors in determining the spatial pattern of flooding regimes. The LMAV flooding regimes dataset provides a scientific basis for the governments to design forest, agriculture, and wildlife management policies to enhance ecosystem services. Landowners also can use this information to make decisions for cropland retirement and tree plantation.

No description available.

Biofuel production-driven land-use change in agricultural land can have impacts on ecosystem services. Since there is no planned mandate after the Renewable Fuel Standard, there are questions about what implications will future land-use changes have on water quality and how do water quality changes, resulting from potential bioenergy scenarios, affect changes in people's well-being? To answer these questions, I will estimate the value of the predicted changes in water quality under biofuel policy scenarios in counties inside the Mississippi River Basin. From this study, I found that as the percent of land-use changes increase across each county, water quality decreased. I also found that for every unit increase for the change in water quality index, the percentage of individuals' willingness to pay for a change in water quality would increase. The predicted willingness to pay for a change in water quality for a given household varied from -$72 to $143.

This study was undertaken to assess the effectiveness of implanted substrates in sampling aquatic macroinvertebrate assemblages associated with stone dikes on the Lower Mississippi River and to obtain basic information on assemblage composition, structure, and patterns of distribution over a dike. For study purposes, stone-filled baskets were implanted into a dike near Vicksburg, Mississippi, in February 1979, and retrieved four months later. The resulting data indicated the presence of a diverse and productive assemblage (38 taxa; average of 101,968 organisms/m²), characterized by net-spinning caddisflies, tube-building chironomids, isopods, and clinging mayflies. The caddisfly, Hydropsyche spp., accounted for over 60 percent of the total organisms collected. A comparison of assemblage data obtained from the surface stones of the implanted substrates with data obtained from adjacent surface stones of the dike indicated close agreement in estimates of both assemblage composition and structure. However, on an average basis, over seventy percent of the total organisms collected in the substrate implants were found below the surface layer of substrate. The importance of this finding to future sampling efforts is discussed. Statistically significant differences in assemblage estimates were encountered over both the length and width of the structure sampled. These findings are discussed both in terms of their potential ecological significance and in terms of future sampling design considerations. / Master of Science