Environmental & Conservation Sciences Doctoral Work

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Ammonia Oxidizing Archaea in Engineered Water and Wastewater Systems: Presence, Activity and Relationship to Heavy Metal Inhibition, and Disinfectants
(North Dakota State University, 2017) Roy, Dhritikshama
Ammonia oxidizing archaea (AOA) have been found as a key player in ammonia oxidation. Over the past decade, AOA have been shown in some cases to outnumber ammonia oxidizing bacteria (AOB) in marine, terrestrial and aquatic environments, and to participate in nitrification. In this dissertation research, AOA along with AOB were examined for their presence and activities in wastewater treatment plants (WWTPs), and water treatment plants (WTPs) employing different disinfectants and their distribution systems (DSs). Firstly, this research investigated the abundance and seasonal variation of AOA and AOB by quantitative polymerase chain reaction targeting the ammonia monooxygenase subunit A gene (amoA) in the biofilm from trickling filters (TFs) and a moving bed bioreactor (MBBR) employed separately at two WWTPs. AOA and AOB dominated nitrifying cultures from the same WWTPs were selected using specific inhibitors, and investigated for nitrification activity. Secondly, this research examined copper inhibition of nitrification by attached and suspended growth ammonia-oxidizing cultures containing different fractions of AOA. The third and final research part investigated AOA and AOB abundance and nitrification activity in different treatment steps of WTPs practicing chloramination and chlorination and distal and proximal zones of their DSs. A laboratory experiment simulating DS conditions with chorine and chloramine was conducted to understand the effects of disinfectant concentration and type, and water temperature on AOA and AOB populations and activity. AOA were dominant in the nitrifying TF (NTF) and MBBR, while AOB dominated in the biochemical oxygen demand TF. AOA and AOB were more abundant during warm months. In-situ nitrification activity showed the oxidation of ammonia to nitrite decreased when AOA populations from the NTF and MBBR were inhibited, demonstrating that AOA contributes to nitrification. Nitrification by the cultures heavily dominated by AOA were less inhibited by copper than the cultures with less AOA dominance. In WTP systems studied, more AOA were observed in chloraminated DS compared to chlorinated DSs. More AOA and AOB were detected in the distal zones than the proximal zones of DSs suggesting that AOA and AOB grew in the distribution systems. AOA had longer inactivation time under cold water temperature compared to AOB.
The Applicability of Physiology for Conservation and Management Purposes: A Case-Study Using the Breeding Season of the Red-winged Blackbird (Agelaius Phoeniceus)
(North Dakota State University, 2017) Mahoney, Jessica
Physiology has the potential to play a unique and important role in conservation and management practices by helping identify the mechanistic responses of populations to environmental changes, and providing physiological tools and knowledge that can be applied to help solve conservation and environmental problems. It has previously been unclear, however, if the increase of physiology in conservation and management literature has translated into the application of physiological tools and knowledge into conservation and management plans. There were two purposes of this disquisition: 1) analyze how physiological tools have been integrated into applied conservation by reviewing USFWS endangered species recovery plans, and provide suggestions to help conservation scientists and physiologists work synergistically to solve conservation and management problems, and; 2) provide an example of how studying the physiology of a species can provide useful information for making management decisions, using the study of stress physiology in the red-winged blackbird (Agelaius phoeniceus) during their breeding season as our case study. Our results suggest that physiology is being underutilized in USFWS endangered species recovery plans. We hypothesize this absence of physiological tools and knowledge in conservation planning is primarily due to a deficit of physiological knowledge passing between physiologists and the cohort of federal agency recovery plan writers. We suggest the need for increased training of federal agency employees, the inclusion of authors with academic affiliations, increased integration of physiology and conservation research, and enhanced communication between all concerned parties. To illustrate how physiology can be useful, we exposed female red-winged blackbirds to predator and nest parasitism effigies, thus causing additional stress, during the breeding season. We were able to examine how females respond behaviorally and physiologically to stress, and how these responses alter their reproductive decisions. We found that females are responding both behaviorally and physiologically to the increased threat of predation and nest parasitism. There is potential to exploit these responses to manage the species, such as causing females to forgo breeding. We also determined that an individual’s stress physiology can be changed when held in captivity. We suggest using caution when trying to extrapolate captive data to wild populations.
Aquatic Macroinvertebrate Response to Shifts in Hydroclimatic Variability and Ecohydrological Conditions in Prairie-Pothole Wetlands: Implications for Biodiversity Conservation
(North Dakota State University, 2020) McLean, Kyle Ian
Ecosystem degradation and subsequent biodiversity loss has plagued freshwater environments globally. Wetland ecosystems, such as the depressional wetlands found in the Prairie Pothole Region of North America, have been heavily impacted by historical land-use change and continue to be vulnerable to continued landscape modifications and climate change. Using existing literature, I summarized how recent shifts in climate coupled with historic and contemporary landscape modifications have driven a shift in wetland ecohydrological variability. However, clear trends in biodiversity were often limited by the spatial and temporal resolution of published research. I used 24 years (1992–2015) of hydrologic and aquatic-macroinvertebrate data from a complex of 16 prairie-pothole wetlands located in North Dakota to relate wetland ecohydrological variability to biodiversity. I used structural equation modeling techniques to test a set of causal hypotheses linking a wetland’s hydrogeologic setting and local climate conditions (i.e., the Wetland Continuum) to changes in hydrology, water chemistry, and biology, with an emphasis on aquatic-macroinvertebrate community response. I then examined the temporal synchrony of aquatic-macroinvertebrate populations to examine the relative importance of landscape-scale controls (e.g., climate, metacommunity dynamics) and wetland-specific controls on community assembly. Using this information, I then quantified among-wetland and amongyear changes in aquatic-macroinvertebrate beta diversity to investigate patterns of biotic homogenization. I found that spatial and temporal variability in aquatic-macroinvertebrate composition was strongly influenced by ponded-water dynamics. In addition to hydrologic controls, the high levels of temporal coherence of aquatic-macroinvertebrate compositional turnover supported the hypothesis that wetland biodiversity is also dependent on metacommunity dynamics. Analyses of spatio-temporal patterns in beta diversity did not reveal climate driven homogenization of aquatic-macroinvertebrate taxa among wetlands. However, shifts towards more permanently ponded water regimes corresponded with lasting shifts in aquatic-macroinvertebrate community composition. The communities of temporarily ponded wetlands maintained high levels of both temporal and spatial beta diversity. My collective findings indicate that the conservation of aquatic-macroinvertebrate diversity is dependent on the conservation of heterogenous, wellconnected, wetland complexes.
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.
Cell Entrapment for Mitigating Fouling in Membrane Bioreactors Treating Domestic Wastewater
(North Dakota State University, 2018) Juntawang, Chaipon
Membrane bioreactors (MBRs) have been a process of choice for wastewater treatment and reuse because of several advantages over conventional process (activated sludge) including superior quality effluent, less biomass yields and more compact design. However, membrane fouling is a major drawback that hampers widespread and full-scale applications of MBRs. Cell entrapment is a relatively new wastewater treatment process. It involves cells artificially entrapped in a porous polymer matrix. In this dissertation research, three versions of entrapped cells-based MBR processes, aerobic MBR, anaerobic MBR and anaerobic forward osmosis (FO) MBR, were developed by using polyvinyl alcohol as a cell entrapment matrix. Their domestic wastewater treatment performances and fouling characteristics were tested and compared with their suspended cells-based MBR counterparts. For aerobic and anaerobic MBRs, entrapped cells-based processes provided similar organic removal but experienced delayed fouling compared to suspended cells-based processes. The entrapment diminished bound extracellular polymeric substances (bEPS) and soluble microbial products (SMP), which are a main culprit of irreversible fouling through pore blocking. Entrapped cells-based aerobic and anaerobic processes had 5 and 8 times lower pore blocking resistance than corresponding suspended cells-based processes. For anaerobic FOMBR, the entrapment protected cells from reverse salt flux leading to slightly higher organic removal. Lower bEPS and SMP in entrapped cells-based FOMBR led to higher permeate flux compared to suspended cells-based FOMBR. The delayed membrane fouling in entrapped cells-based MBRs means lower costs associated with membrane cleaning processes and longer membrane lifespan. Another contribution of this study is novel knowledge on fouling conditions and mitigation for FOMBR, an emerging wastewater treatment process.
Chironomids Then and Now: Climate Change Effects on a Tundra Food Web in the Alaskan Arctic
(North Dakota State University, 2019) Lackmann, Alec Ray
Although climate change is a global phenomenon, the Arctic is warming faster than any other region on earth. These climatic changes have driven rapid regional changes over the past half-century in both the physical landscape and the ecosystems therein. One such ecological interaction is between migratory shorebird survival and local insect emergence. Annually, tens of millions of migratory shorebirds travel to the Arctic to rear their young in the relative absence of predators, but in a relative abundance of food (insects). Over evolutionary time, these trophic levels have coupled: shorebird chicks tend to hatch during the period of highest terrestrial insect availability. However, climate change is currently uncoupling this food-web synchrony, creating potential for trophic mismatch. In the High Arctic near Utqiaġvik (formerly Barrow), Alaska, trophic mismatch between nesting shorebirds and their insect food base is already detectable. In this ecosystem, flies in the Family Chironomidae (non-biting midges) dominate the prey trophic level in the avian food web. We have found that the pre-emergence development of one particular midge, Trichotanypus alaskensis, defies conventional wisdom of the Family, as this species molts to an additional fifth larval instar prior to pupation and emergence (all other chironomids are known to have four larval instars). We discovered an Utqiaġvik midge that reproduces asexually, a species that was not documented in the 1970s. Utilizing controlled temperature rearings of Utqiaġvik midge larvae, we discovered that as temperatures rise, emerging chironomid adults are generally smaller in size. We have found that chironomid pre-emergence developmental rates follow a positive exponential relationship as temperatures increase, can vary by taxon, yet are consistent across field and lab settings for a given taxon. At Utqiaġvik in the 2010s, chironomid emergence occurs 8-12 days earlier than it did in the 1970s. These findings shape our understanding of trophic mismatch in this arctic food web.
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.
Determining Greenhouse Gas Emissions and Nitrogen Dynamics of Solid Beef Manure Applied to Fargo-Clay Soil of the Red River Valley
(North Dakota State University, 2018) Niraula, Suresh
Land application of solid beef manure may prompt greenhouse gases (GHGs) - nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) emissions. Nitrogen (N) in manure can also be lost through ammonia volatilization (NH3), leaching (NO3-), denitrification, and erosion. The objectives of this research were to assess the effects of (i) land application of solid beef manure (SM) on emission of GHGs, NH3 volatilization, and corn (Zea mays L.) yield, (ii) soil moisture [(30, 60, and 90% water-holding capacity (WHC)] on GHGs and NH3 emissions from urea and manure application, and (iii) soil temperature (5, 10, 15, and 25°C) on GHGs and NH3 emissions from urea and manure amended Fargo-Ryan silty clay soil of the RRV. The two-year growing season cumulative N2O emission (cN2O) ranged from 0.3 (non-fertilized, NF) to 1.2 (urea only, UO) kg N ha-1. The UO reduced cumulative carbon dioxide (cCO2) by 42% compared to manure N sources. The cumulative CH4 (cCH4) emission ranged from -0.03 to 0.23 kg CH4-C ha-1 CH4-C ha-1, with the highest emission from manure with straw bedding (BM). Manure reduced cNH3 by ~11% compared to UO. Cumulative soil N in 2017 were significantly greater by 11%, respectively, compared to 2016. Nitrogen source did not show any difference in grain yield and grain N uptake in field study. In the laboratory, across WHC levels, 1.01% of the total applied N was lost as N2O at 60% WHC from urea treated soil. Soil CO2 from manure was up to two times the emission from CF treated soils. The cumulative NH3 volatilization loss from soil ranged from 29.4 to 1250.5 µg NH3-N kg−1 soil, with the highest loss from CF amended soils at 30% WHC. In addition, laboratory study showed cumulative GHGs and NH3 emission generally increased with increase in temperature, with the highest emission observed at 25 °C. The results highlight the challenge of meeting crop nutrients demand while reducing GHG emissions by selection of an N source.
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.
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.
The Effect of Zinc Oxide Nanoparticles on Plants, and on Host-Pathogen Interactions
(North Dakota State University, 2019) Deka, Priyanka
Zinc oxide nanoparticles (ZnO NPs) are a type of engineered nanomaterial that is currently being explored for use in different aspects of agriculture. So far, research on this area is limited to evaluating the phenotypical responses of plants to a high concentration of the NPs which is realistically not feasible in the actual environment. This research aims to investigate the molecular-level interactions between ZnO NPs and plants, together with another significant component of the environment, a fungal plant pathogen. Prior to studying these molecular-level interactions, the uptake of ZnO NPs in planta was validated using a fluorescent zinc ion sensor, Zinpyr-1 and a zinc ion chelator, TPEN in confocal laser scanning microscopy (CLSM) and Transmission Electron Microscopy (TEM). Phenotypical effects were studied in soybean plants exposed to environmentally relevant concentrations of ZnO NPs and bioaccumulation of zinc was studied in seeds of soybean and other soy products. The next phase of this research focused on investigating the physiological responses of plants exposed to ZnO NPs. This was achieved by elucidating the complete transcriptome of the plants using a Next Generation sequencing (NGS) platform, RNA seq. A significant part of this research emphasized on exploring the effects of ZnO NPs on host-pathogen interactions. The model monocot plant, barley was used in this study, together with a necrotrophic pathogen, Pyrenophora teres f. teres (Ptt). The barley line which was used, CI5791 is resistant to the disease Net Form Net Blotch (NFNB), caused by Ptt. Rapid responses of plants to ZnO NPs were observed that subsided at the later time-points, whereas the heightened responses to the pathogen alone (P) and combined application (ZnO NP + P) persisted. Exposure to ZnO NPs also induced transcriptional reprogramming in the Ptt inoculated plant that resulted in compromised immunity in the otherwise resistant barley, due to the persistence of salicylic acid (SA)-related genes. In ZnO NP-exposed Arabidopsis thaliana, the effects were contradictory. From the barley and Arabidopsis expression data, it could be concluded that both species react differently to ZnO NPs, giving a glimpse of the differential responses that ZnO NPs may elicit in different plant species.
Essays on Land Conversion, Crop Acreage Response, and Adoption of Conservation Practices: Evidence from the Dakota's
(North Dakota State University, 2017) Parvez, Md. Rezwanul
This research is composed of three essays. It highlights the driving factors of land conversion and crop acreage response focusing on North Dakota agriculture and estimates the benefits of conservation land measures at west central South Dakota watershed. The major questions that are addressed here are how and why agricultural producers decide among different land use choices, crop selection, and land conservation measures and how their decision vary over time? The first essay examines the long run land conversion trend interconnected with change in crop, oil, and ethanol prices, climate and renewable fuel policy mandates. Data are obtained from Cropland Data Layer from 1997 to 2015 period of National Agricultural Statistics Service (NASS) at the USDA. The first essay employs a Seemingly Unrelated Tobit Regression approach to better understand the connection between land conversion and crop prices, biofuel policies, biophysical environment. Key findings indicate land-use conversion from grassland to cropland is relatively higher across the ND counties. The second essay is designed to investigate the relationship between crop acreage response and socio-economic and environmental drivers. We use prices for crude oil, planted acres of major crops (corn, wheat, soybean, hay) and prices from the period of 1990 to 2015. This essay focuses on corn acreage response due to crop prices, energy policies, climate and other socio-economic factors using a Fixed Effect parameter framework. The final essay estimates environmental benefits due to adoption of conservation practices. In other words, it analyzes the economic and environmental benefits of implemented conservation practices at Bad River watershed in South Dakota using an integrated framework. For example, in an article in the Global Journal of Agricultural Economics, Extension and Rural Development (2016), a Benefit Cost Analysis model is utilized to assess soil conservation benefits and evaluate economic impacts of conservation measures at a watershed scale. The economic analysis includes estimation of benefit cost ratio, annual rate of return of conservation practices. Key findings suggest that benefit value of sediment reduction average $2.13 per ton expressed in constant (year = 2000) dollars and the ratio of benefits to costs is greater than 1.
Evolutionary and Ecological Processes in Conservation and Preservation of Plant Adaptive Potential
(North Dakota State University, 2022) Di Santo, Lionel Nicolas
Anthropogenetic disturbances, such as habitat loss and fragmentation, overexploitation, and climate change have diminished population sizes of many species, increasing risks of population extirpation or species extinction. Consequently, conservation of genetic variability, to preserve and maintain rare species’ evolutionary potential and avoid within-population inbreeding, is a major goal of conservation biology. For plants, various approaches and guidelines have been developed to preserve species’ genetic diversity ex situ (“off-site”). However, effective methods to guide conservation and management decisions without relying on the availability of genetic data or knowledge about population size and population genetic structure are lacking. With the first two chapters of my dissertation, I aimed to complement existing ex situ strategies by investigating surrogates for estimating genetic variation to optimize conservation of rare species’ evolutionary potential when access to genetic data is limited. My results demonstrated that guiding population sampling using environmental and geographic distances, as opposed to randomly selecting source populations, can increase genetic diversity and differentiation captured in simulated ex situ collections. Likewise, my research showed that for species with largely heritable seed traits, morphological variation estimated from contemporary seed collections can be used as a proxy for standing genetic variation and help inform sampling efforts aiming to optimize genetic diversity preserved ex situ. Although strategies targeted to conserve rare species’ evolutionary potential where genetic data may be lacking are needed, the increasing affordability of next-generation sequencing technologies is increasing access to genomic data for rare species. With my third chapter, I investigated whether inferring rare species’ evolutionary history from genomic data may help inform conservation practices. My results demonstrated that teasing apart spatial and temporal effects of stochastic and deterministic processes on population genetic structure may be used to estimate past and contemporary changes in populations’ evolutionary potential, as well as to evaluate risks and benefits of genetic rescue as a management strategy. Overall, my PhD research establishes tools and approaches to preserve genetic variation for rare species using different types of data. As world’s biodiversity continue to decline, tool development to accommodate species-specific data availability for preservation of genetic variation is crucial.
Examination of the Period of Preparation for Breeding in Male and Female Songbirds
(North Dakota State University, 2017) Needham, Katie Beth
In virtually all species, reproduction must be precisely timed to coordinate breeding and rearing of offspring with favorable conditions. It is imperative for individuals to time the highest energetic cost to themselves or highest needs by offspring with greatest food availability in either abundance or nutrient make-up. To accomplish this, individuals must integrate signals conveying both internal and external status and accordingly alter the activity of the reproductive axis. To date most efforts to identify variation in control mechanisms for reproduction in seasonally breeding animals have focused on the brain as the initiator for reproduction. However, recent studies have re-directed attention to two other potential tissues, the pituitary and ovary, where variation in brake sensitivity may be important. To this end, a series of experiments were performed in two songbird species to elucidate the hormonal role in timing of breeding and the interaction of an energetic trade-off on the decision to breed in both males and females. I used two species, the wild dark-eyed junco (Junco hyemalis) and the wild-caught captive house sparrow (Passer domesticus) as model systems to address the following questions: 1) What physiological mechanisms explain individual variation in onset of gametogenesis? And 2) How are mechanisms of energy integrated with the reproductive axis’ control of reproduction and timing of breeding to regulate energetic trade-offs? Specifically, we focused the role of testosterone in males (Chapter 2), and mechanisms downstream of the hypothalamus in females (Chapter 3). Next, in Chapter 4, the question of whether an energetic demand would reduce sperm quality was addressed. Lastly, in Chapter 5, we asked if an energetically costly immune challenge would result in the delay of clutch initiation. The results of these studies demonstrate the significant differences between sexes in the signals conveying an individual’s internal and external status in order to alter activity of the reproductive axis, and therefore timing of breeding. Collectively, these findings provide further evidence that females are ‘in the driver’s seat’ for onset of breeding and should be the focus of future research.
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.
Graphene Oxide Supported Metal Oxide Nanohybrids for Aqueous Arsenic Removal
(North Dakota State University, 2021) Das, Tonoy Kumar
Arsenic contamination of drinking water is a major public health concern affecting more than 200 million people globally. Iron(Fe)-based adsorbents though promoted for aqueous arsenic removal because of their low cost and easy availability, their field application is limited due to their low efficiency and slow adsorption kinetics. In this work, two graphene oxide (GO)-Fe nanohybrids, namely GO-supported nano magnetite (GM) and GO-supported nanoscale zero-valent iron (GFeN), were compared for arsenic removal. Controls were run with bare (i.e., no GO) nanoscale zero-valent iron (FeNP) and nano magnetite (M). GFeN worked more efficiently (>90%) over a wide pH range (3-9) for both the inorganic arsenic species, As(III) and As(V). GM worked well at pH 3 (>90% efficient) for As(V), and pH 9 (80%) for As(III). GFeN exhibited better aqueous dispersibility with a zeta potential of -21.02 mV. In GFeN and FeNP, surface complexation was dominant in the adsorption of both As(III) and As(V), and electrostatic attraction played a limited role. In GM and M, As(V) removal was controlled by electrostatic attraction while As(III) adsorption was ligand exchange and surface complexation. The arsenic removal data based on normalized iron content in the adsorbents indicated that the nanohybrids (GFeN and GM) removed arsenic more efficiently compared to the bare nanoparticles (FeNP and M) with GFeN performing the best. Arsenic adsorption capacities of GFeN were found to be 306 mg/g for As(III) and 431 mg/g for As(V). The GO-sheets in GFeN acted as reservoirs for the electrons released during surface corrosion of the FeNPs. The stored electrons were transferred back to the FeNPs to reduce the oxidized iron surface, and the rejuvenated surface helped in additional arsenic removal. The arsenic desorption pattern from two As(V)-sorbed nanohybrids (GFeN and graphene oxide-supported ceria (GO-CeO2)) was studied. GFeN released ~5.73% and GO-CeO2 released ~0.94% of sorbed arsenic over a period of two years. While sorbed arsenic remained as As(V) on the GFeN surface, some As(V) in GO-CeO2 got reduced to As(III). The surface oxide composition in GFeN (FeOOH and Fe2O3) and GO-CeO2 (Ce3+/Ce4+ ratio) underwent changes over time and that played a role in arsenic desorption.
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.
Holocene Postglacial Fluvial Processes and Landforms in Low Relief Landscapes
(North Dakota State University, 2020) Phillips, Zachary Rockford
Postglacial rivers are part of the relatively young low-relief landscape system left behind by glaciers. Over time, postglacial rivers are susceptible to both minor and major channel planform changes as the Earth and its newly exposed rivers adjust to new isostatic and geomorphic equilibriums. Those planform changes result in topographic features that are well preserved among the largely unaltered landscape and offer opportunities to learn about the processes that create them. This work focuses on those minor and major planform changes and the resulting landforms, with a focus on processes effecting the glaciolacustrine Red River Valley. Here, three studies were conducted, two regarding minor planform changes and one focusing on major planform changes. Studies included in this work regard 1) the spatial distribution of meander cutoffs and meander cutoff relief on the Red River, 2), avulsion timing and length resulting from isostatic tilting and 3) mobile river ice and bank interaction frequency, locations, and erosion in meandering rivers. Results show that rivers develop meander cutoffs that faster in areas where geologic materials are more easily eroded and their relief shows a positive relationship with the rate of river incision. Major channel path changes (avulsions) in the presence of isostatic tilting were found to be most frequent soon after river establishment while rates of isostatic rebound are high enough to outpace channel incision. River ice was found to most frequently interact with the outer banks of channels with long, tight bends and high sinuosity, potentially contributing to the meandering process. From these results it can be interpreted that postglacial rivers were highly dynamic early in their history and have stabilized over time, with most of the changes occurring in areas with more erodible alluvium. Presently, rivers undergo most of their changes during the spring thaw when mobile river ice is impacting the banks, with sinuous river reaches impacted most frequently by mobile river ice.
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.
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.

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