Environmental & Conservation Sciences Doctoral Work

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Multi-Element Composition of Triglochin Maritima L. from Contrasting Habitats including Hot Springs and Metal Enriched Areas
(North Dakota State University, 2011) Sunwar, Sharmila
The aim of this PhD research was to study multi-element composition in wetland plants from contrasting habitats, including hot springs, temporary wetlands, and metal-rich areas. Triglochin maritima L. (seaside arrowgrass) was chosen for the study because this species is common in alkaline/saline soils and is adapted to diverse habitats. Eleocharis rostellata, Juncus balticus, Salix exigua, S. boothii, and S. wolfii were also included in the study. Field studies and greenhouse experiments were conducted to study the multi-element composition in plants. In the greenhouse experiment the effects of temperature and soil biota on multielement uptake in T. maritima were studied. Root-zone soils and plant samples were analyzed for 32 - 50 elements using inductively coupled plasma OES/MS spectrometry. The expected outcomes from this research were: 1) the development of multi-element fingerprints for T. maritima and other plant species from contrasting habitats, and 2) a better understanding of the effects of temperature and soil biota on multi-element uptake in T. maritima. Habitat specific element concentration patterns in T. maritima were observed; concentrations of Mn, Li, and B were high in plants from hot spring influenced wetlands, whereas Ca, P, Mg, Fe, Sr, Ba, Ti, and Cu were higher in the plants of temporary wetlands. J. balticus and Salix species from mine impacted and uncontaminated sites revealed distinct differences in multi-element fingerprints. J. balticus showed high concentrations of S, K, Mn, Fe, Cu, Al, As, and Cd at contaminated sites compared to un-contaminated sites. Multi-element fingerprints of Salix species showed that S. boothii had higher concentrations of Mn, Fe, Al, and Ti compared to S. exigua and S. wolfii. To our knowledge for the first time the association of mycorrhizal fungus in T. maritima was confirmed, and significant effects of temperature on element concentrations, contents, and their translocation in plants were observed. Generally, the distribution of the total contents of P, Na, Mn, B, Cu, Mo, Li, Sr, Ti, and Cs in both roots and leaves were lower at 40 °C compared to 20 and 30 °C, but their distribution and translocation from root to leaves were higher at 40°C. Even though the biological and physiological functions of Li, Sr, Ba, Rb, and Ti in plants are not fully understood, these elements were substantially taken up by T. maritima, and significant positive correlations of these elements were found with elements that have known biological functions. Overall, concentrations of Ca, P, Mg, Mn, B, Sr, and Ba in T. maritima showed variation due to differences in habitats, temperature, and experimental growing conditions (greenhouse and field condition). Concentration patterns of Na, K, and Zn were species specific and affected by temperature. Li concentrations varied due to habitat differences, growth conditions, and species differences. Future research directions could include: 1) identification of the fungal species associated with T. maritima and studies to elucidate their possible role in survival of T. maritima in the elevated temperature of hot springs, 2) the effects of soil factors, such as salinity and 3) seasonal variation in uptake and translocation, particularly for the less studied elements with yet unrecognized but potential biological functions in plants.
Multi-Element Fingerprinting of River Sediments to Identify Diffuse Pollution Sources
(North Dakota State University, 2011) Wijeyaratne, Dimuthu Nilmini
This study was carried out in the Souris and Turtle Rivers in North Dakota. The aim of this study was to develop multi-element fingerprints of the Souris River and Turtle River sediments and to evaluate the suitability of these fingerprints to assess the geographic origin of potential pollutants of the two rivers. Preliminary analysis of Souris River sediment samples confirmed that the multi-element fingerprinting can be used to assess the sediment and contaminant loading patterns. Laboratory experiments were performed to assess the validity of linear mixing assumption in multi-element fingerprinting studies. The results of these experiments verified the assumptions and showed that there is a statistically significant spatial and temporal variation in the element concentrations depending on their mobility and re-deposition. Field studies were conducted in the Souris River and Turtle River to assess the variation of element concentrations in the top riverbed samples along the main rivers and their tributaries. The sediment contribution from the tributaries and the phosphorus concentrations in the main channel were used to calculate the phosphorus contributions from the tributary sediments to the Souris River. The differences in phosphorus contributions from tributaries were related to land use, underlying geology, and the size of the watersheds of the tributaries in the Souris River watershed. Similar analysis was used in the Turtle River to calculate Arsenic, Cadmium and Selenium contribution from the tributaries to the Turtle River. The differences in the contribution of these elements were related to the underlying geology and the size of the watersheds. This study provides a detailed analysis of element concentrations and relative sediments and element loading rates from the tributaries to the main rivers along the Souris and Turtle Rivers in North Dakota. The multi-element fingerprinting technique can be successfully used as a tool to identify the relative contribution of sediments and assessing and tracing pollution sources in rivers. Multi-element fingerprinting provides a relatively low cost, rapid tool for sediment tracking, without the need for addition of exotic chemicals such radio-tracers or dyes to natural ecosystems.
Biogeochemistry of Wet Ecosystems from Root Zone to Landscape
(North Dakota State University, 2012) Kissoon, La Toya Tricia
The biogeochemistry of wetland ecosystems varies, causing them to act as sources, sinks, filters or transformers of nutrients and pollutants. Wetland plants play important roles in the cycling of elements in wet ecosystems. The structural and physiological adaptations that allow these plants to colonize wetland habitats as emergent or submerged species contribute to biogeochemical processes in wetland substrates. Rhizosphere (root zone) oxidation, iron and manganese oxide precipitation, acidification of the rhizosphere, root exudation, and microbial activity influence the mobility of elements in wetland substrates. Both emergent and submerged wetland plants can alter conditions in the rhizosphere that influence the mobility of elements. These plants are also capable of removing elements such as Cd, Cu, Fe, Mn, N, P and Zn from solution and accumulating them in their tissues. Root zone studies were carried out in the greenhouse using the wetland plants Typha angustifolia (cattail) and Rumex crispus (curly dock) and in the field using Triglochin maritima (seaside arrowgrass) to determine differences in element concentrations in the root and bulk zone under different soil moisture conditions. Studies involving shallow lakes of Minnesota were carried out to determine relationships among (1) landscape variables (e.g. lake watershed size, percent agriculture, percent woodland), water and sediment characteristics (turbidity, chlorophyll-a, organic content, particle size), (3) element concentrations in waters and sediments, and (3) plant abundance and community composition. The studies reported here showed that different factors influenced the distribution of multiple elements in the root zone of emergent wetland plants and in waters and sediments of shallow lakes. First, the root zone studies indicated that pH, redox and moisture content of wetland soils influenced the distribution of elements in the rhizosphere and subsequent uptake of these elements by wetland plants. Second, the shallow lake study showed that land cover uses (agriculture and woodland), lake watershed size, and sediment physical characteristics (organic content and particle size) influenced the distribution of elements in waters and sediments of shallow lakes. Concentrations of these elements, land cover uses, open water area, turbidity, chlorophyll-a concentrations and sediment physical characteristics influenced abundance and distribution of submerged and floating plants.
Phosphate Removal and Recovery Using Iron Nanoparticles and Iron Cross-Linked Biopolymer
(North Dakota State University, 2012) Almeelbi, Talal Bakheet
Nanoscale zero-valent iron (NZVI) particles and iron cross-linked alginate (FCA) beads were successfully used for the first time for phosphate removal and recovery. NZVI was successfully used for phosphate removal and recovery. Batch studies indicated a removal of ~96 to 100% phosphate in 30 min (1, 5, and 10 mg PO43--P/L with 400 mg NZVI/L). Phosphate removal efficiency by NZVI was 13.9 times higher compared to Microscale ZVI (MZVI) particles. The successful rapid removal of phosphate by NZVI from aqueous solution is expected to have great ramification for cleaning up nutrient rich waters. The presence of sulfate, nitrate, and humic substances and the change in ionic strength in the water marginally affected phosphate removal by NZVI. A maximum phosphate recovery of ~78% was achieved in 30 min at pH 12. Novel iron cross-linked alginate (FCA) beads were synthesized, characterized and used for phosphate removal. The beads removed up to 37-100% phosphate from aqueous solution in 24 h. Freundlich isotherm was found to most closely fit with experimental data and the maximum adsorption capacity was found to be 14.77 mg/g of dry beads. The presence of chloride, bicarbonate, sulfate, nitrate, and natural organic matters in aqueous solution did not interfere in phosphate removal by FCA beads. The phosphate removal efficacy FCA beads was not affected due to change in pH (4-9). Nanosacle zero-valent iron (NZVI) and iron cross-linked alginate beads were also tested for phosphate removal using actual wastewater treatment plant effluent and animal feedlot runoff. The FCA beads could remove ~63% and ~77% phosphate from wastewater and feedlot runoff in 15 min, respectively. Bioavailability of phosphate was examined using algae and higher plants. Phosphate and iron bioavailability of the NZVI sorbed phosphate was examined by supplying spent particles (NZVI with sorbed phosphate) to Tyee Spinach (Spinacia oleracea) and algae (Selenastrum capricornutum). Results revealed that the phosphate was bioavailable for both the algae and spinach. Also, presence of the nanoparticles enhanced the algae growth and plant growth and increases in biomass and plant length were observed. Iron (from spent NZVI) was found to be bioavailable for spinach.
Ecological Complexity of Non-Native Species Impacts in Desert Aquatic Systems
(North Dakota State University, 2012) Henkanaththegedara, Sujan Maduranga
Without an adequate understanding of complex interactions between native and non-native species, management of invasive species can result in unforeseen detrimental impacts. I used both field and laboratory experiments to study reciprocal species interactions between the endangered Mohave tui chub (Siphateles bicolor mohavensis) and invasive western mosquitofish (Gambusia affinis). I also examined the impacts of both fish species on the aquatic invertebrate communities in desert springs. I demonstrate a case of intraguild predation (IGP) as a mechanism facilitating co-persistence of the endangered Mohave tui chub with invasive mosquitofish using field mesocosm experiments. In this case of IGP, adult tui chub prey on adult and juvenile mosquitofish, while adult mosquitofish prey on tui chub eggs and/or larvae. I conducted laboratory predation trials to assess if IGP was size-structured due to predator gape-limitation. I explored sex specific differences in gape-size limitation in mosquitofish, because mosquitofish are sexually dimorphic. Larval tui chubs had lower survival in the presence of female mosquitofish than in the presence of males. Reciprocally, male mosquitofish had lower survival than the females in the presence of Mohave tui chub. These results combined with vulnerability modeling supported that IGP in this system is size structured based on gape-size limitation. These results collectively suggest size-structured IGP may facilitate the co-persistence of these two fish species. My findings also suggest that mosquitofish may not be a limiting factor for the persistence of the endangered Mohave tui chub. Further, habitats currently harboring mosquitofish were considered as future refuge habitats for Mohave tui chub, a management option previously un-available. In addition to such reciprocal interactions between fish species, recently established fish populations may impact unique invertebrate communities. Mesocosm experiments with sympatric and allopatric populations of tui chub and mosquitofish showed negative impacts of both fish species on changes of invertebrate community structure. Specifically, fish caused population declines and, in some cases, extirpations of various invertebrate taxa. These results suggest important conservation implications of invasive fish as well as protected fish transplants into fishless desert springs. Overall my research emphasizes the complexity of ecological interactions between native and non-native fish species in desert aquatic systems.
From Bray-Curtis Ordination to Markov Chain Monte Carlo Simulation: Assessing Anthropogenically-Induced andor Climatically-Induced Changes in Arboreal Ecosystems
(North Dakota State University, 2013) Madurapperuma, Buddhika D.
Mapping forest resources is useful for identifying threat patterns and monitoring changes associated with landscapes. Remote Sensing and Geographic Information Science techniques are effective tools used to identify and forecast forest resource threats such as exotic plant invasion, vulnerability to climate change, and land-use/cover change. This research focused on mapping abundance and distribution of Russian-olive using soil and land-use/cover data, evaluating historic land-use/cover change using mappable water-related indices addressing the primary loss of riparian arboreal ecosystems, and detecting year-to-year land-cover changes on forest conversion processes. Digital image processing techniques were used to detect the changes of arboreal ecosystems using ArcGIS ArcInfo® 9.3, ENVI®, and ENVI® EX platforms. Research results showed that Russian-olive at the inundated habitats of the Missouri River is abundant compared to terrestrial habitats in the Bismarck-Mandan Wildland Urban Interface. This could be a consequence of habitat quality of the floodplain, such as its silt loam and silty clay soil type, which favors Russian-olive regeneration. Russian-olive has close assemblage with cottonwood (Populus deltoides) and buffaloberry (Shepherdia argentea) trees at the lower elevations. In addition, the Russian-olive-cottonwood association correlated with low nitrogen, low pH, and high Fe, while Russian-olive- buffaloberry association occurred in highly eroded areas. The Devils Lake sub-watershed was selected to demonstrate how both land-use/cover modification and climatic variability have caused the vulnerability of arboreal ecosystems on the fringe to such changes. Land-cover change showed that the forest acreage declined from 9% to 1%, water extent increased from 13% to 25%, and cropland extent increased from 34% to 39% between 1992 and 2006. In addition, stochastic modeling was adapted to simulate how land-use/cover change influenced forest conversion to non-forested lands at the urban-wildland fringes in Cass County. The analysis yielded two distinct statistical groups of transition probabilities for forest to non-forest, with high transition probability of unchanged forest (0.54≤; Pff≤; 0.68) from 2006 to 2011. Generally, the land-uses, such as row crops, showed an increasing trend, while grains, hay, seeds, and other crops showed a declining trend. This information is vital to forest managers for implementing restoration and conservation practices in arboreal ecosystems.
Influences of Climate Variability and Landscape Modifications on Water Dynamics, Community Structure, and Amphipod Populations in Large Prairie Wetlands: Implications for Waterbird Conservation
(North Dakota State University, 2014) Wiltermuth, Mark Thomas
Northern prairie pothole wetlands provide crucial habitat for numerous waterbirds. However, wetland abundance and quality in the Prairie Pothole Region of North America has declined because of agricultural landscape modifications. Effective management of waterbird populations relies on understanding how landscape modifications alter wetland hydrology and biological communities in context of climate-driven wet-dry periods. A common modification involves consolidation of smaller more-temporary wetlands into larger more-permanent ones. I evaluated whether consolidation drainage has progressive-chronic effects on hydrology of remaining wetlands during 2003-2010 in the Prairie Pothole Region of North Dakota. For wetlands in topographic basins that were not already full, rate of water surface area change was positively correlated with consolidation drainage during a wetting phase, but negatively correlated during a drying phase. This unbalancing of water budgets through wetting and drying phases suggests that 1) consolidation drainage has a progressive-chronic effect on wetland hydrology; and 2) wetlands receiving water in extensively drained landscapes will continue to increase in volume through each climate fluctuation until they reach their spilling point, then stabilize. Proportion of wetlands covered by cattail was negatively correlated with increases in water depth, thus cattail coverage may increase as water levels stabilize as a result of consolidation drainage. Fish were present in 57% of wetlands and probability of fish occurrence was greater in wetlands that had greater water depth and wetland connectivity. Weak evidence suggests amphipod densities decreased where there was extensive drainage and increased in more full basins, probably due to improved overwinter survival. The alternative stable states hypothesis predicts clear versus turbid observable states that reflect differing trophic structures in wetlands. I conducted a landscape-scale evaluation of this hypothesis by examining the distribution of remotely-sensed chlorophyll a concentrations within 978 wetlands. My findings suggest that trophic structure in prairie wetlands is better understood within a continuum of trophic status rather than discrete states. My results provide an improved understanding of how land use and climate variability influence productivity in wetlands across the region and should help shape future research and conservation priorities focused on wetland services and waterbird populations.
Impact of Carbon Nanotubes on Bacterial Viability: Indicators, Mitigation, and Role of Phage Shock Proteins
(North Dakota State University, 2014) Le, Tu Thi Anh
The toxicity of single walled carbon nanotubes (SWCNTs) to a model bacterium, Escherichia coli ATCC 8739 was investigated. Estimates of E. coli viability following treatment with SWCNTs were similar using four viability methods: plate count, galactosidase enzyme assay, LIVE/DEAD® Baclight™ assay, and RNA quantificatio. Pristine SWCNTs, carboxylic functionalized SWCNTs (SWCNT-COOHs) and hydroxyl functionalized SWCNTs (SWCNTOHs) were used to assess toxicity. Regardless of the length of SWCNTs, the toxicity was in the following order: SWCNT-OHs < SWCNTs < SWCNT-COOHs. While there was no difference in the impact of short and long SWCNT-OHs, the long pristine SWCNTs and SWCNT-COOHs were more toxic than the corresponding short SWCNTs. The viability of cells exposed to all three types of SWCNTs was greater with increasing cell density. Alterations of cell morphology ware observed after the cells were exposed to SWCNTs. Entrapment of cells in alginate and polyvinyl alcohol (PVA) as a means to limit the antibacterial effect of SWCNTs was examined. The results showed that cell entrapment could reduce the bactericidal effects of SWCNTs. Calcium alginate and PVA provided equivalent cell protection against SWCNTs. The toxicity of SWCNTs for entrapped cells depended on the length and concentrations of SWCNTs, the presence of functional groups, and the initial cell density. Transcriptomic and proteomic analyses were used to study the molecular mechanisms by which SWCNTs induce bactericidal activity. Expression levels of genes and proteins, particularly phage shock proteins (Psp) that are known to react under membrane stress such as iv pspA, pspB, and pspC, changed following cell exposure to SWCNTs. Expression of the Psp operon was affected by the length, concentration, and functionalization of SWCNTs. Overall, this study provided multiple methods that can be used to quantify the toxicity of SWCNTs for bacterial cells. A way to mitigate the bactericidal effects of SWCNTs was identified and verified. Gene and protein expression, particularly expression of the Psp operon, were reported in cells stressed by exposure to SWCNTs.
Impact of Artificial Aeration on Nutrients in a Small Eutrophic Lake
(North Dakota State University, 2015) Balangoda, Anusha Rupika
The Heinrich- Martin Dam Impoundment (HMDI), located in northcentral LaMoure County, North Dakota, is an important water body for fishing, boating, and other recreational activities. To eliminate the thermal stratification and low dissolved oxygen (DO) zone near the bottom, an artificial aeration system was installed and operated by the North Dakota Game and Fish Department (NDG&F). This study was conducted to investigate whether aeration improved water quality of HMDI and to evaluate aeration as a tool to effectively manage eutrophication in lakes of this type. Field monitoring and laboratory analyses were conducted during three consecutive summers, in 2010, 2011 and 2012, to evaluate the impact of aeration on the spatial and temporal variation of physical, chemical, and biological water quality. Variables monitored included total and dissolved forms of inorganic nitrogen (N) and phosphorus (P), chlorophyll a, turbidity, water temperature and dissolved oxygen (DO). Field sampling was carried out during aerated conditions in 2010 and 2012 and under non-aerated conditions in 2011. The study revealed no significant differences between aeration and non-aeration conditions in soluble reactive phosphorus (SRP), total phosphorus (TP), or total nitrogen (TN) concentrations in the water column. In contrast, mean ammonia-nitrogen concentration at the near-bottom layers during non-aerated conditions decreased significantly under artificial aeration, while mean nitrate and nitrite concentrations increased significantly under aeration. Under aerated conditions, dissolved inorganic nutrients, TN, TP, temperature, and algae were homogenously distributed throughout the water column. Aeration expanded aerobic habitats for fish and distributed bio-available nutrients, stimulating algal growth throughout the water column. These results indicate that the existing aeration system vertically mixed nutrients throughout the water column of the HMDI. Chlorophyll a results showed that aeration distributed algae throughout the water column and circulated available nutrients for their growth. In addition, the results indicated that aeration improved water quality as measured by Secchi depth, turbidity, DO and algal biomass based on recommended levels by NDDoH. In a nitrogen-limited, phosphorus-rich water body, like HMDI, lowering phosphorus (P) load rather than nitrogen (N) load is recommended as a means of reducing algal biomass.
Life History and Interspecific Co-Persistence of Native Imperiled Fishes in Single Species and Multi-Species Ex Situ Refuges
(North Dakota State University, 2015) Goodchild, Shawn Christopher
Like many imperiled fishes, the endangered Pahrump Poolfish (Empetrichthys latos latos) is managed in ex situ refuges. I investigated life history characteristics of females from two such populations at Lake Harriet and Shoshone Stock Pond. Lake Harriet is a relatively large lake with low fish densities located at relatively low elevation and low latitude, while Shoshone Stock is a small pond with high fish densities at a higher elevation and latitude. Females from the Lake Harriet population were larger, and had greater fat content, reproductive allocation, and ‘clutch’ size than females from the Shoshone Pond population. This divergence, which occurred in three decades, may result in a phenotypic mismatch if the fish are used as a source for restocking their native habitat or stocking new refuges. Poolfish conservation may require establishing new populations; however, many sites are inhabited by non-native fish and/or other protected fish species. Thus, managers may wish to consider establishing multi-species refuges that may even already include undesirable species. I established experimental communities that included allopatric and sympatric communities of Poolfish, Amargosa Pupfish (Cyprinodon nevadensis), and invasive Western Mosquitofish (Gambusia affinis). Pupfish persisted in sympatry with both poolfish and mosquitofish, but had higher juvenile production when maintained in allopatry. By contrast, poolfish juvenile production was high in allopatry, but virtually absent in the presence of other species. To evaluate the generality of these findings, I established experimental allopatric and sympatric communities of poolfish or pupfish with mosquitofish from two populations that differed in body size: Garrett mosquitofish were approximately twice the mass of Wabuska mosquitofish. Poolfish juveniles had high survival in allopatry, but produced virtually no juveniles when sympatric with either of the two mosquitofish populations. Pupfish juvenile survival was higher in allopatry than sympatric with Garrett mosquitofish, which in turn was higher than sympatric with Wabuska mosquitofish. These results were consistent with the earlier experiment suggesting that poolfish were functionally extirpated but pupfish maintained substantial production in the presence of mosquitofish. These findings suggest that poolfish should be maintained in single species refuges, but that multi-species refuges may protect imperiled pupfish species.
Impact of Climate Variability on Streamflow and Water Quality in the North Central United States
(North Dakota State University, 2015) Ryberg, Karen Renee
Long-term precipitation, temperature, and streamflow records were used to compare changes in precipitation and potential evapotranspiration to changes in runoff within 25 stream basins. Historical changes in the region appear to be more consistent with complex transient shifts in seasonal climatic conditions than with gradual climate change. Annual peak streamflow data were divided into two populations, snowmelt/spring and summer/fall, to test the hypotheses that, because of changes in precipitation regimes, the odds of summer/fall peaks have increased and, because of temperature changes, snowmelt/spring peaks happen earlier. The odds of summer/fall peaks occurring have increased across the study area. In northern portions of the study region, snowmelt/spring peaks are occurring earlier by 8.7 to 14.3 days. Tree-ring chronologies and historical precipitation data in a region around the Souris River Basin, were analyzed to model past long-term variations of precipitation. Results show that precipitation varies on multi-decadal time scales. The Red River of the North drains much of eastern North Dakota and northwestern Minnesota and flows north into Manitoba, Canada, ultimately into Lake Winnipeg, so phosphorus transport is an International concern. Phosphorus changes over time were determined and phosphorus concentrations at the International border, when adjusted for variability in streamflow (flow-normalized), have generally increased from 1972-2012; however, most of that increase happened in the 1970s. Flux, the total amount of phosphorus transported, has increased dramatically in recent decades; however, when adjusted for streamflow variability (so that flux is from variation caused by the occurrence of high- or low-flow conditions), the flow-normalized flux has declined in recent years. This indicates that an important reason for increased flux is climatic – the wet conditions experienced since 1993. These changes have implications for water interests, such as potential changes in leadtime for flood forecasting or changes in the operation of flood-control dams or wastewater treatment plants. Results suggest that the recent wet period may be a part of natural variability on a very long time scale and that this not only has implications for flood risk, but for nutrient export to Canada.
Northern Leopard Frogs in North Dakota: Assessing the Conservation Status of a Widespread Amphibian Species
(North Dakota State University, 2015) Fisher, Justin David Lee
North Dakota’s midcontinent location within the Prairie Pothole Region is widely known for the dense wetlands. These highly productive wetlands are mixed within an agricultural mosaic which places increased pressure on water quality and overall wetland persistence. These threats to wetlands affects other, more common species which are presumed to have healthy populations but lack statewide information. Such is the case with the northern leopard frog (Lithobates pipiens). I examined genetic variation for 41 populations across the state. Genetic diversity was not correlated with latitude, but was negatively correlated with longitude. Along this genetic diversity gradient, there was a distinctive break near the 100th meridian, a historical boundary between the arid western United States and the wet eastern side. Further data exploration revealed wetland densities to be positively correlated with genetic diversity whereas precipitation and anthropogenic disturbance were not correlated with genetic diversity. I also examined population genetic structure to identify conservation units. Strong population structuring was defined by the Missouri River, identifying the Western Badlands and Western Prairie conservation units. Further structuring of L. pipiens occurred within these two defined conservation units with rough correspondence to local watersheds. Additionally, I used approximate Bayesian computational analyses to evaluate coalescence times among the 10 defined units. The Western Prairie and Western Badlands unit shared common ancestry 13,600 to 18,100 generations ago. The coalescence times of the 6 populations within the Western Prairie unit varied from as recently as 588 generations to 10,900 generations, while populations within the Western Badlands unit varied as recently as 2,890 generations to 5,220 generations. In addition to the northern leopard frog genetics research, I conducted research that considered how sampling biases may lead to inaccurate estimates aquatic invertebrate abundance. I present an assessment of potential biases associated with sampling a population of the amphipod Gammarus lacustris in the presence of Polymorphus spp. acanthocephalan parasites shown to increase positive phototaxis in their amphipod hosts. Results indicated that the highest captures of G. lacustris individuals were in benthic traps, however, parasitized individuals were captured most often in surface traps.
Ecology of Cryptosporidium Parasites in Wild Rodent Populations
(North Dakota State University, 2015) Stenger, Brianna Leigh Schneck
Cryptosporidium is a genus of ubiquitous parasites that have been detected worldwide in nearly 500 species of amphibians, birds, fish, mammals, and reptiles. Most research has focused on the Cryptosporidium species and genotypes infecting humans and livestock, because of the public health significance and economic importance of the diarrheal disease cryptosporidiosis. Relatively little is known about Cryptosporidium-host dynamics in wildlife hosts, even though a wide range of wildlife species are susceptible to Cryptosporidium. Insights into ecology and host-parasite dynamics in wild populations are necessary to understand the biology and evolution of Cryptosporidium; to predict the emergence of human and livestock pathogens; and to clarify Cryptosporidium taxonomy and systematics. The focus of this research was to study the ecology of Cryptosporidium in populations of cricetid (voles, Peromyscus mice, muskrats) and sciurid (squirrels and chipmunks) rodents, and characterize Cryptosporidium taxa by sequencing multiple genetic loci (18S rRNA and actin genes). Paralogous copies of the 18S rRNA gene in Cryptosporidium genotypes from wild rodents were common and affected phylogenetic inferences. Eastern chipmunks (Tamias striatus) were infected with Cryptosporidium chipmunk genotype II, which had 18S rRNA gene paralogs that shared ~93% similarity. The degree of divergence has not been previously described in any Cryptosporidium taxa, but is similar to the divergence described in Plasmodium species, which have functionally distinct 18S rRNA gene copies. Marmotini squirrels were mainly host to novel Cryptosporidium genotypes, and to the best of our knowledge, we provide the first molecular characterization of Cryptosporidium in black-tailed prairie dogs (Cynomys ludovicianus). Cryptosporidium host adaptation and specificity was not evident in in Sciurini rodents and they were host to two zoonotic taxa, C. ubiquitum and Cryptosporidium skunk genotype. In conclusion, Cryptosporidium was prevalent in cricetid and sciurid rodents, and the extent of host adaptation varied among Cryptosporidium taxa as they are likely shaped by differences in host-parasite ecology and evolution. The rodents sampled are not significant reservoirs of zoonotic Cryptosporidium, with the exception of tree squirrels. Sequencing multiple genetic loci helped identify the presence of paralogs and resolve cryptic Cryptosporidium taxa, which strengthened phylogenetic inferences leading to a better understanding of Cryptosporidium systematics.
Understanding the Relationships between Plant Communities, Fish Communities, and Sediment Chemistry in Pristine Shallow Lake Wetlands, Red Lake, MN
(North Dakota State University, 2016) Hummel, Stephanie Elizabeth
Over 90% wetland loss in many areas of the United States has triggered extreme concern for declining biodiversity and loss of ecosystem services. Studies assessing ecological characteristics of unaltered wetlands are critical to interpreting potential responses to anthropogenic changes and how ecosystem characteristics and services might respond to future climate dynamics. Previous research shows fish and plant communities play an important role in shallow lake ecology by creating stability within the clear state. Understanding these mechanisms in a pristine setting is important for successful conservation and restoration. Our objectives, part of a long term monitoring study (2009-2015), were 1) Evaluate patterns in multi-element concentrations of pore water along a gradient from upland areas through emergent vegetation to the open water of shallow lake wetlands 2) Assess seasonal changes of multi-element concentrations of pore water during the growing season of shallow lake wetlands 3) Measure the influence of fish communities species composition on plant communities species composition 4) Evaluate how sediment chemistry impacts plant communities. We evaluated pore water chemistry on two lakes using dialysis vials from June-October 2014. We selected 24 shallow lakes located within Red Lake Nation Indian Reservation, MN, USA to conduct the remaining objectives. At each lake we assessed fish community structure and abundance using fyke nets and experimental gill nets for a 24-hr period during July. Aquatic and emergent vegetation was assessed simultaneously by rake throws and Daubenmire frame, and sediment samples were collected by taking a surface grab sample. Sediment samples were taken in the open water and emergent vegetation zones. Pore water did not change across a gradient from upland to open water, but did change over the season from June to October. We found fish community composition did not change significantly from 2009 to 2015, but fish biomass significantly decreased from 2009 to 2015. No species-specific relationships between vegetation and fish existed, but species specific relationships existed between vegetation and sediment characteristics in both the open water and emergent vegetation zones. Results will be used as reference points for restoration and conservation, and serve for a better understanding of shallow lake state stability.
Habitat Use and Foraging Ecology of Bats in North Dakota
(North Dakota State University, 2016) Nelson, Josiah
Habitat use is a key component to understanding the conservation needs of species. While an array of quantitative analyses for studying fine-scale habitat use and selection have been developed, such methods have rarely been applied to bat species, with most work focused at a broad scale or using qualitative methods. Insectivorous bat communities face major threats from habitat conversion, exploitation of natural resources, and the impending spread of white-nose syndrome. Hence, detailed knowledge of their habitat needs is critical for developing effective management plans. In North Dakota, little was known about local bat populations prior to 2009, with essentially no knowledge of habitat associations and preferences of bat species. The overall objective of this research was to survey habitats across North Dakota to document species occurrences within key ecological regions and to assess the influence of fine-scale habitat characteristics on community diversity and foraging patterns. We further aimed to assess the foraging habitat selection of little brown bats, Myotis lucifugus, a species of conservation concern. Our specific objectives were to: 1) assess species’ occurrence and distributions within North Dakota; 2) assess the influence of habitat and the availability of water resources on species diversity and community-level foraging activity; 3) identify habitats associated with areas of high foraging activity; 4) identify indicator species that characterize key habitats; 5) assess foraging habitat selection of female M. lucifugus; 6) and assess individual variation in habitat selection of M. lucifugus. From 2009 to 2012, mist netting and acoustic surveys were conducted to document species occurrence at 68 sites. From 2012 to 2015, targeted acoustic surveys were conducted at 37 sites to assess foraging activity levels in variable habitats. In 2014 and 2015, data-logging telemetry receivers were used to assess foraging habitat selection of M. lucifugus. The presence of 11 species was confirmed in the state. We found that bat community diversity and foraging activity were influenced by fine-scale habitat characteristics. M. lucifugus selected for edge habitats and nearby water sources. These results will be valuable for the conservation and management of bats and provide baseline information for future research on habitat use of bats.
Iron Nanoparticles and Biopolymers for Plant Nutrient Fortification
(North Dakota State University, 2016) Hossain, Mohammad Enayet
Novel iron (Fe) cross-linked alginate (FCA) beads were used for aqueous phosphate removal. Batch experiments were conducted with the beads using three different concentrations of phosphate (5, 50 and 100 mg PO43--P/L) as well as environmentally relevant (eutrophic lakes) concentration of 100 μg PO43--P/L. About 80-97% phosphate was removed within 3 h. for lower concentrations of phosphate. The maximum phosphate sorption capacity was found to be 78.7 mg PO43--P/g of beads. Phosphate removal was not affected because of the presence of Cl-, HCO3-, SO42-, NO3- and natural organic matter (NOM). FCA beads were also used with actual lake waters (11-69 μg PO43--P/L) and 81-100% phosphate removal was observed in 24 h. The FCA beads having a point of zero charge (PZC) of 9.2 make it an ideal candidate for phosphate removal in eutrophic lakes. Phosphate-laden spent iron cross-linked alginate (FCA) beads were used in hydroponics to evaluate the bioavailability of P and Fe using lettuce (Lactuca sativa) as a test plant. Phosphate-laden spent FCA beads were found to support the plants throughout the growth period. The bioavailability of P and Fe in the spent beads is promising considering the importance of phosphorus and iron in global nutrient security. Experiments were also conducted with lettuce and spinach (Spinacia oleracea) to evaluate the availability of iron from nanoscale zero-valent iron (NZVI). In both plants, bare NZVI enhanced the uptake of Fe as well as other essential elements. The results indicate that biofortification of spinach and lettuce with Fe is possible. The enhanced uptake of iron and other elements by lettuce and spinach is likely to have implications on global nutrient security. In another experiment, an iron-regulating gene (LsHA2) in lettuce was investigated to gain insights into the strategy taken by plants for acquisition of Fe from a readily unavailable source, e.g., NZVI. The gene of interest was found to be regulated by the presence or absence of available iron in the solution. This research is likely to give us insights into the mechanism of plant nutrient fortification with nanoparticles.
Seasonality of Some Arctic Alaskan Chironomids
(North Dakota State University, 2016) Braegelman, Shane Dennis
Arthropods, especially dipteran insects in the family Chironomidae (non-biting midges), are a primary prey resource for many vertebrate species on Alaska’s Arctic Coastal Plain. Midge-producing ponds on the ACP are experiencing climate warming that may alter insect seasonal availability. Chironomids display highly synchronous adult emergence, with most populations emerging from a given pond within a 3-5 day span and the bulk of the overall midge community emerging over a 3-4 week period. The podonomid midge Trichotanypus alaskensis Brundin is an abundant, univoltine, species in tundra ponds near Barrow, Alaska, with adults appearing early in the annual emergence sequence. To better understand regulation of chironomid emergence phenology, we conducted experiments on pre-emergence development of T. alaskensis at different temperatures, and monitored pre-emergence development of this species under field conditions. We compared chironomid community emergence from ponds at Barrow, Alaska in the 1970s with similar data from 2009-2013 to assess changes in emergence phenology. Overwintering larvae of T. alaskensis increased in larval size, dry weight, and head capsule size between pond thaw and pupation, indicating substantial larval growth as well as development preceding pupation in the year of emergence. Pupal development showed a consistent degree hour requirement independent of mean daily temperature. We detected a significant advancement of overall midge emergence by about one week in Barrow tundra ponds since the late-1970s. Chironomid midge development clearly is regulated by temperature, but at least some species require substantial feeding and growth during the post-thaw period, raising the possibility of nutritional influences on emergence phenology. Under a warming climate, altered adult emergence timing may result from earlier thaw, warmer temperatures, and possible changes in food availability.
Impact of Artificial Aeration on Phytoplankton Growth and Seasonal Succession in a Eutrophic Lake
(North Dakota State University, 2016) Valkov, Veselina Aleksandrova
Excessive phytoplankton growth caused by increased loadings of nitrogen (N) and phosphorus (P) is the most visible symptoms of eutrophication. At higher densities phytoplankton creates water quality problems such as offensive taste and odor, impaired aesthetics, depletion of dissolved oxygen (DO), and cyanotoxicity concerns. Artificial aeration is commonly used to eliminate thermal-stratification, to increase DO levels in lakes and reservoirs, and to control P-release from sediments. This research was conducted to evaluate the impact of aeration on sediment nutrient release, nutrient availability for phytoplankton growth, phytoplankton seasonal succession and Cyanobacterial growth. Water samples for nutrient and phytoplankton analysis were taken from a eutrophic reservoir in North Dakota under aerated and non-aerated conditions, where sediment nutrient release was identified as a major source of N and P. Aeration eliminated thermal stratification and increased DO concentrations throughout water column. When aerated, aerobic condition at the sediment-water interface reduced sediment P-release by nearly 50%. However, phosphorus release due to degradation of organic matter continued and was likely enhanced by increased DO levels. Induced mixing from aeration made nutrients equally distributed in the water column and more available for phytoplankton growth, which led to more phytoplankton growth measured as higher chlorophyll-a concentration and phytoplankton biovolume. Results of this study reveal that increased mixing and nutrient availability due to aeration are the major reasons for changes in phytoplankton seasonal succession resulting in favoring growth and shifting growth-periods of diatoms, dinoflagellates, and Cyanobacteria. Seasonal succession of phytoplankton community was also affected by nitrogen limitation in the reservoir. Ability of Cyanobacteria to grow at low N concentrations and low N:P ratios stimulated nitrogen-fixing cyanobacterial species to bloom and maintained higher cyanobacterial growth. Aeration did not reduce algal and cyanobacterial growth in the reservoir.
Crop Acreage Response Modeling in North Dakota and Greater Midwest
(North Dakota State University, 2017) Chowdhury, Nazea H Khan
Our research consists of two papers. First paper focus on the trend of North Dakota (ND) crop acreage changes and include economic factors (expected prices of crops, input price, crop yield, revenue of crops) and climate factors (precipitation, minimum and maximum temperature, growing degree days, and palmer drought severity index). We are using Geographic Information System (GIS) database for cropland areas throughout ND for the years 1998 through 2013. But we are using five crops for our analysis. We use Seemingly Unrelated Tobit Left Censored Regression and Monte Carlo Simulation techniques for our analysis. We also include renewable fuel standard dummy (year 2005 and 2007). Findings suggest that prices of crop, yield, revenue, input price significant impact on crop acreage. Marginal effects of crop price increase by $1 to own acreage of barley, corn, soybean, wheat, and oilseeds ranges between 50 to 295 acres, 28 to 572 acres, -24 to 45 acres, -198 to -39 acres, and 7 to 48 acres throughout ND and statistically significant except soybean. Elasticity of own-price to acreage of barley, corn, soybean, wheat, and oilseeds are 1.16%, 1.23%, 0.17%, -0.16%, and 0.53%, respectively, and statistically significant except soybean. Second paper mainly focus on three states ND, South Dakota (SD), and Minnesota (MN) causes of crop acres planted changes due to economic factors as well as weather factors. We are using Seemingly unrelated regression and Monte Carlo Simulation technique for that paper. We produce a balanced panel dataset with annual observations of the planted acreages of each of the five crops in each of the three states, along with the relevant price and yield variables for each crop and pertinent precipitation and temperature variables for each year in each state. Monte Carlo Simulation technique used to calculate own-price elasticity of MN state barley, corn, soybean, wheat, and sunflower to their own acreage are -0.506%, 0.197%, 0.116%, 0.566 %, and 11.34%, respectively; in SD state are -0.739%, 0.312%, 0.290%, 0.309%, and 1.72%, respectively and statistically significant except barley crop elasticity. This research findings will help forecast future agricultural land use trends & crop area response.
Processing Trade-offs in a Cellulosic Biorefinery
(North Dakota State University, 2017) Nahar, Nurun
Commercial scale cellulosic biorefineries face significant challenges to produce low-cost fermentable sugar from biomass. Biorefinery processing steps are interrelated and trade-offs between process parameters impact the cost and efficiency of the overall system. Although densified biomass as a biorefinery feedstock would improve biomass supply logistics, it has not been considered viable due to high energy and emissions associated with the densification process. However, the potential synergies of biomass densification with downstream processing steps are critical. An energy-efficient system with improved supply logistics, reduced severity pretreatment, and improved hydrolysis efficiency will lower the cost of sugar production from cellulosic biomass. The objective of this research was to increase overall process efficiency of biorefineries by understanding how different process parameters affect the hydrolysis efficiency. Processing trade-offs in pretreatment and enzymatic hydrolysis for densified and non-densified biomass for economical sugar production were evaluated. A life cycle perspective was taken to compare fossil energy and greenhouse gas (GHG) emissions from pelleted and non-pelleted corn stover during transportation and soaking in aqueous ammonia (SAA) pretreatment. A model developed to demonstrate the interaction of enzymatic hydrolysis factors to improve hydrolysis efficiency showed that enzyme loadings had a more significant effect on hydrolysis rates than pH or temperature. Economical optimal enzyme loadings were lower than loadings to maximize yield, loadings can be adjusted to maximize profit based on enzyme costs, ethanol price, and process temperature. Pelleted corn stover allowed reduction in SAA-pretreatment severity with different combinations of temperature, time, and ammonia concentration to produce 90% or higher glucose yields. This suggests possible economic and environmental benefits of using pelleted biomass as a biorefinery feedstock. Use of pelleted biomass reduced transportation fossil energy and GHG emissions by 25%. A significant reduction of energy (89%) for SAA-pretreatment was achieved with pelleted biomass due to lower pretreatment time and higher solid loadings. Use of pelleted biomass allowed doubling of pretreatment solid loadings, which lowered pretreatment reactors from 59 to 9, in addition to associated water and chemical savings. This study demonstrated that SAA pretreatment is not feasible for non-pelleted biomass, but process synergies make SAA pretreatment possible for pelleted biomass.

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