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Assessing Relationships Of Moose Populations, Winter Ticks, And Forest Regeneration In Northern New Hampshire, Daniel Henry Bergeron

Master's Theses and Capstones

This study examined relationships among winter ticks, weather, and the nutritional and reproductive status of moose, and the impact of moose on regeneration of commercial forests in northern New Hampshire. Three methods were evaluated to assess their usefulness as indices of relative winter tick abundance, and predictors of tick epizootics: tick counts on harvested moose and roadside, spring hair-loss surveys were considered time and cost effective to index winter tick abundance. Physical characteristics of harvested moose (1988--2009) indicated ovulation rates (∼20%), and mean body weight (<200 kg) of yearlings declined since 1988; because adult body weight and ovulation rates remained stable, habitat quality was unlikely related. Winter tick epizootics are likely influenced by abnormal large scale weather events, as evident in the widespread die-off in 2002 associated with warm snowless conditions into mid-December 2001 that extended tick transmission to moose. Spring and fall weather should be monitored for unusual conditions causing high tick abundance and tick loads, particularly warm and snowless conditions in April and December. Mean stocking rate of all age classes of commercial tree species was above the threshold in all regions (49--87%); forest regeneration was not considered a regional problem at any moose density.

Unraveling The Mystery Of Leaf Reddening In Seagrasses, Alyssa B. Novak

Doctoral Dissertations

Seagrass meadows around the world are declining due to natural and anthropogenic stressors, including global climate change. Recently, more attention has been given to identifying responses that offer resistance to stressors so that researchers can better manage seagrasses for resilience to environmental change. Leaf reddening, the expression of red coloration in leaves, is a well-documented response in terrestrial plants that has been shown to increase resilience to stress, but has been poorly understood in seagrasses. To increase our understanding of the prevalence, causes, and function of leaf in seagrasses, surveys were conducted in the world's six seagrass bioregions and a …

Study Of The Rate And Spectrum Of Spontaneous Mutations, Way Sung

Doctoral Dissertations

Mutations are the initial force responsible for all aspects of genetic variation, and are a central part to evolution in all organisms. Yet despite its importance, the previously high cost that is associated with surveying mutations at a genome-wide scale has limited the understanding of the mutation process in eukaryotes. However, recent high-throughput sequencing technology has greatly reduced the cost of surveying mutations. By applying high-throughput sequencing to mutation accumulation experiments, we have begun to characterize the genome-wide mutation spectrum of eukaryotes.

Across all eukaryotes, we observe a biased rate of G/C-> A/T mutations that exceeds the number of A/T- …

Satellite-Derived Fluorescence Quantum Yields As Indicators Of Phytoplankton Photophysiology, Deborah Goodwin

Doctoral Dissertations

Understanding and quantifying phytoplankton physiological variability is essential for analyses of biogeochemical cycling, climate change and ecosystem processes. Satellite measurements of chlorophyll indicate phytoplankton biomass but hold minimal direct information about the organisms' photosynthetic capabilities: however, remote sensing-derived fluorescence quantum yields have the potential for monitoring phytoplankton photophysiological states on a global scale. Recent research has demonstrated the effects of both nutrient stress and photoacclimation on fluorescence yield. Here, a novel satellite product comprising seven years of fluorescence quantum yields, derived from MODIS/Aqua normalized fluorescence line heights and corrected for pigment packaging effects, is evaluated and explored. Fluorescence yields are …

Character Displacement In Burkholderia Biofilm Communities And The Effect Of Adaptive History On The Evolution Of Niche Breadth, Crystal Nicole Ellis

Doctoral Dissertations

Ecologists agree that biodiversity is essential for maintaining highly productive and stable ecosystems, yet the mechanisms that generate and preserve diversity are unknown in many habitats. Competition for shared resources may cause selection to favor niche specialization, which reduces competition and reinforces diversity. If the environment is significantly altered, the ecological history of the remaining colonizer may influence fitness and capacity for diversification in new environments. In many cases, specialists have limited adaptive potential due to trade-offs generated by niche-specific adaptation; however, generalists may be adaptable in many habitats, which would make them good pioneer species for colonization. We investigated …

Assessing Social-Ecological Resilience And Adaptive Capacity In The Face Of Climate Change: An Examination Of Three Communities In The Crown Of The Continent Ecosystem, Bradley B. Johnson

Doctoral Dissertations

This research examines the social-ecological resilience and adaptive capacity of the Crown of the Continent Ecosystem through a suite of three case study communities and the impacts of climate change on the ecosystem's hydrologic regime. The Crown of the Continent Ecosystem spans the U.S.-Canadian border; case study communities composed of Kalispell and Choteau, Montana and Fernie, British Columbia fall on both sides of the border.

Primary data was gathered through a "bottom-up" qualitative approach utilizing an online survey followed by a semi-structured interview process with stakeholders in natural resource dependant industries and government at the local, state, and federal levels …

Detection Of Mortality In Tropical Forests Using Remote Sensing: From Treefall Gaps To Large Disturbances, Fernando Del Bon Espirito-Santo

Doctoral Dissertations

The frequency, severity, and intensity of natural disturbances in tropical forests continually re-shape forest structure. At small scale, branch or tree-falls gaps and subsequent recovery are important mechanisms for carbon cycling. At landscape scale, large disturbances (blow-downs) may also play a role on the structure and composition of tropical forests. Quantitative studies of natural disturbances across the occurrence spectrum (branch fall-gaps to blow-downs) are rare for the Amazon. Remote sensing coupled with intense field work data collection provides the means to analyze the dynamic of tropical forests at multiple scales. In this dissertation three aspects of natural disturbances were examined: …

Interactions Between Adaptive Mutations In The Environment And The Consequences For Adaptation In Escherichia Coli, Kenneth Mark Flynn

Master's Theses and Capstones

Phenotypic plasticity, epistasis or both are expected to influence the adaptive value of mutations and, by extension, how organisms adapt to new environments. We investigated interactions among five mutations that arose and fixed in a laboratory-evolved population of E. coli in a variety of different external environments. Overall, we found that positive pleiotropy tended to be positive rather than antagonistic and that epistatic interactions were common regardless of the external environment. The nature of the epistatic interactions depended strongly on the external environment and altered which adaptive paths were selectively accessible. Ultimately, achieving high fitness in a new environment was …

Studies Of Net Community Productivity In A Near-Coastal Temperate Ecosystem, Olivia De Meo

Master's Theses and Capstones

Understanding the biological contribution to the carbon cycle is important to accurately calculate oceanic carbon budgets. The biological contribution to air-sea flux can be expressed as net community productivity (NCP), or the difference between gross primary production and community respiration. This study conducted two experiments to constrain NCP in a near-coastal region. The first experiment conducted in the western Gulf of Maine (GoM) sought to identify an indirect optical proxy for NCP that would allow for the determination of NCP remotely by satellite in the future. NCP results indicated that the GoM was near equilibrium during our study. Changes in …

Seasonal, Biogeochemical, And Microbial Response Of Soils To Simultaneous Warming And Nitrogen Additions, Alexandra R. Contosta

Doctoral Dissertations

Climate warming and nitrogen deposition are global environmental threats that could alter soil microbial communities and the biogeochemical processes they perform. Few studies have examined interactive effects of elevated temperatures and nitrogen inputs. Many studies have also not considered the role that season plays in mediating the response of soils to warming and nitrogen. Finally, most research has not linked changes in the soil microbial community with ecosystem-scale dynamics. One objective of this dissertation was to examine season-specific microbial and biogeochemical responses to simultaneous warming and nitrogen additions. Another aim was to investigate whether warming and nitrogen can restructure microbial …

Existing Regulatory Circuitries Govern Backbone And Acquired Host Association Factors In The Human Pathogen Vibrio Parahaemolyticus, Jennifer C. Mahoney

Doctoral Dissertations

Vibrio parahaemolyticus is a poorly characterized human gastrointestinal pathogen whose virulence mechanisms are not well understood. Though closely related to Vibrio cholerae, V. parahaemolyticus infections are inflammatory and utilize virulence traits that are unique from the Cholera toxins yet remain poorly characterized. Vibrio spp. in general share an extensive core genome dedicated to environmental survival and unique, often horizontally acquired, gene content that is reserved for species specific lifestyles. This diversity has resulted in a genus of highly specialized bacteria partaking in dramatically different lifestyles ranging from symbiosis to pathogenesis. We propose that a comparative genomic and transcriptomic analysis of …

Herbage Mass Accumulation In An Intensive Rotational Grazing System At Unh's Organic Dairy Research Facility, Ashley Green

Master's Theses and Capstones

Pasture-based animal management in the Northeast U.S. relies on the ability to efficiently estimate pasture production and animal intake. Accuracy and precision of a rising plate meter, NDVI meter, and height measurements for estimating pasture biomass were compared relative to hand-clipped samples. Pasture measurements were used to describe biomass accumulation, lactating dairy herd intakes, and re-growth patterns for intensively rotated pastures. Pastures were measured from May-September, 2009 at the UNH Organic Dairy Research Facility in Lee, NH. The rising plate meter provided the most robust estimates of biomass (R²=0.58, SEE=2.73). Forty-seven paddocks were measured for 82 total grazing events; grazing …

Genes Differentially Expressed At 1 Day, 6 Weeks, And 6 Months Of Age In Aortas Of Spontaneously Atherosclerotic White Carneau Pigeons, Suzanne Lee Pearlman

Master's Theses and Capstones

Genetics is reported to be the primary causative factor for individuals diagnosed with atherosclerosis, in the absence of known risk factors. The development of atherosclerosis in White Carneau (WC) pigeons is of genetic origin, making it an excellent model to study genetic factors.

Representational Difference Analysis (RDA) was used to determine genes differentially upregulated between three ages, at the celiac bifurcation of the aorta in WC pigeons. Genes responsible for spontaneous initiation of atherosclerosis were hypothesized as being differentially expressed at 1 day, while those differentially expressed at 6 weeks and 6 months were related to progression.

Multiple candidate genes …

Effect Of Carex Rostrata Removal On Methane Emissions From A Temperate Peatland, Genevieve L. Noyce

Master's Theses and Capstones

Peatlands are a large natural source of atmospheric methane (CH4). Carex rostrata, a sedge species, has a critical role in the production, oxidation, and emission of CH4 from these systems. This study examined the changes in CH4 emissions from a temperate peatland after removing all aboveground C. rostrata biomass. Methane flux, dissolved CH4 concentration at various depths, C. rostrata green leaf area, temperature, and water table depth were measured from June 2008 to November 2010.

There is a strong positive correlation between C. rostrata green area and CH4 flux and the mean summer CH4 flux from the control plots was …

Identification And Characterization Of Photorhabdus Temperata Mutants Altered In Hemolysis And Virulence, Christine A. Chapman

Master's Theses and Capstones

Photorhabdus temperata is an invertebrate pathogen and nematode symbiont that is commonly used as a biological control agent in the management of commercial crop pests. The focus of this study was to investigate the poorly understood molecular elements involved in the expression of hemolysis and virulence in this bacterium. A 10,000 transposant library was screened using a blood agar plate assay to identify mutants altered in hemolytic activity. A total of 74 mutants displaying defective, delayed, or early hemolysis were identified and subsequently tested for altered virulence in the Greater Waxmoth, Galleria mellonella, using an in vitro mortality assay. Ten …

Incidence, Abundance, Post-Harvest Processing And Population Diversity Of Pathogenic Vibrios In Oysters From The Great Bay Estuary, Jong Whan Yu

Master's Theses and Capstones

Shellfish-borne vibrio diseases have increased recently in the US, particularly in cooler, northern areas. Harvest area monitoring and post-harvest processing (PHP) have been implemented to reduce Vibrio disease risks in marketed shellfish, and rapid and reliable detection methods are needed to assess these risks. Both culture based and qPCR detection methods were useful for detecting V. parahaemolyticus (Vp) in oysters. QPCR is more rapid and less subjective, while the culture based method allowed detection of lower Vp concentrations in cold-water oysters where the Vp population diversity was more clonal. Depuration and relaying were assessed as PHP strategies for reducing Vp …

The Spatial And Temporal Distribution, Population Growth Strategies And Options For The Removal Of The Invasive Shore Crab Carcinus Maenas In Two New Hampshire Estuaries, Beth Allison Fulton

Master's Theses and Capstones

The spatial and temporal distribution of the green crab, Carcinus maenas, along with various green crab population parameters, were studied in two New Hampshire estuaries over a one-year period from November 2009 to October 2010. Results show that foraging activity in Great Bay Estuary peaked in December and March, and in HSE, in April and November. Crabs in both estuaries experienced synchronous breeding periods. Males experienced two molts per year in April and November, while females molted synchronously in June. Embryogenesis was accomplished within the month of June. Minimum size at maturity for females in New Hampshire was larger than …

Analysis Of Arabidopsis Thaliana Protein Phosphatase 2a C Subunit Expression, Megan M. Thompson

Master's Theses and Capstones

Reversible protein phosphorylation is required for presumably most biological pathways. One of the major enzymes involved in eukaryotic dephosphorylation is Protein Phosphatase 2A (PP2A). PP2A is composed of three subunits: A (scaffolding), B (regulatory), and C (catalytic). Our lab is interested in determining the function of the five C subunits (C1, C2, C3, C4 and C5) in Arabidopsis thaliana. We have identified a Na+-induced altered root growth phenotype in c4 mutant plants. The goal of this project was to determine expression of the five C subunit genes throughout the life cycle of Arabidopsis with emphasis on correlating the location of …

Discovering Signaling Events In The Actinorhizal Symbiosis, Nicholas J. Beauchemin

Master's Theses and Capstones

Although the symbiosis between Frankia and actinorhizal host plants has been widely studied, very little is known about the initial molecular interactions. To address this issue, Casuarina cunninghamiana root exudates were collected and tested on Frankia Ccl3. Frankia growth yield was enhanced by root exudates but Frankia could not utilize them as a sole carbon and energy source. Exposure to root exudates caused Frankia hyphal curling and surface property changes in fatty acids and carbohydrates. Pre-exposure to root exudates also decreased the time required for nodule initiation. The results show that root exudates and Frankia physiological changes for symbiosis are …

The Effects Of Historic Earthen Barriers On Northern New England Tital Marshes, Jordan W. Mora

Master's Theses and Capstones

Berms, defined as historic earthen barriers, represent one type of hydrological modification introduced by humans in the tidal marshes of northern New England. Three different research approaches were applied to study the impact of berms on various tidal marsh dynamics. The descriptive study shows that restricted flooding from berm interference can result in significantly altered physical gradients in addition to landward subsidence and pool development. The results from the transplant experiment indicate that the altered landward structure affects the relative importance of biological interactions, namely herbivory, in controlling plant species distribution. The predictive GIS analyses illustrate the location of 34 …

Identification And Characterization Of Photorhabdus Temperata Mutants Altered In Cell Surface And Symbiosis, Cintia R. Felix

Master's Theses and Capstones

Photorhabdus temperata forms a mutualistic association with the entomopathogenic nematode Heterorhabditis bacteriophora. Nematode growth and development has an obligate requirement for the bacterial symbiont. The objective of this study was to identify and understand cell surface properties that are required for symbiosis. A previously generated library of 10,000 P. temperata transposon mutants was screened for altered surface properties via a calcofluor dye-binding assay. Seventeen mutants were identified and tested in vitro for symbiosis. Key mutants were tested for symbiosis and insect pathogenesis in vivo with Galleria mellonella larvae. Five mutants showed at least a 10-fold decrease of IJ yield. Four …