Life Sciences Commons^™

Spatial And Hydrologic Effects Of Climate Change And Urbanization On Freshwater Fish Communities In North Georgia Watersheds, Mayuko Mizutani

Master's Theses

Urbanization and climate change are altering streamflow and land cover across the southeastern United States, threatening freshwater biodiversity in rivers already burdened by impoundments and habitat loss. I investigated how changes in streamflow and land cover might affect fish community biodiversity in the Etowah River watershed of North Georgia. By combining a dataset of fish collections from 1999 through 2019 with contemporaneous land use and daily streamflow, I was able to model fish community responses to urbanization and climate-driven hydrologic changes and then forecast fish community structure under multiple CMIP6 global climate models and greenhouse gas emissions scenarios (SSP2-4.5 and …

A Genetic Analysis Of The Rare Endemic Astragalus Ripleyi Barneby, Juan Antonio Jaramillo-Chico

Master's Theses

Astragalus ripleyi Barneby is a rare endemic species found in the San Luis Valley of the southern portions of the Rocky Mountains in Colorado and New Mexico. Though not federally listed as endangered, the species is on the Bureau of Land Management’s Sensitive Species List, warranting protection and continued management. This study aims to provide information about the genetic health of the species to inform conservation efforts and provide updated management recommendations. A genetic health analysis was conducted investigating the levels of diversity present in the species, how genetic diversity is structured across the known range of the species and …

Determining The Role Of Maumee River Sediments In Microbial Nitrogen Transformations And Net Fluxes, Ashlyn Stanalonis

Master's Theses

The Maumee River watershed is the largest of any river feeding into the Laurentian Great Lakes and is primarily comprised of agricultural land uses. Most cultivated crops require fertilizer applications to sustain growth and productivity. Fertilizer runoff is a major source of nutrient loading to the river, and total nitrogen (N) and phosphorus (P) inputs contribute to eutrophication and cyanobacterial blooms in the western basin of Lake Erie. This study aimed to characterize Maumee River sediments as net N sinks or sources to the western basin and evaluate N removal efficiency (a valuable ecosystem service) to determine if river sediments …

Blue Crab Reproductive Output And Phenology In A Changing Climate, Blaise Rohan

Master's Theses

Globally, ecosystems are experiencing rising temperatures due to climate change, with potential consequences for reproductive investment and timing in many species. Blue crabs, Callinectes sapidus, support valuable commercial fisheries throughout the U.S. Atlantic and Gulf coasts, and understanding variation in reproductive output has important management and conservation implications. This study examined two components of blue crab reproduction: (1) reproductive investment across populations spanning multiple latitudes (New York, New Jersey, North Carolina, Mississippi, and Texas), using a space-for-time substitution to assess the effects of varying thermal regimes on fecundity and egg quality, and (2) spawning phenology in North Carolina from …

A Comparison Of Survival, Growth, And Stress Resilience In Three Different Lineages Of The Pacific Oyster (Crassostrea Gigas) Farmed On The California Central Coast, Victoria F. Hanshaw

Master's Theses

Aquaculture of Pacific oysters on the US West Coast is routinely impacted by seasonal unexplained mortality events. To better understand these large-scale mortality events in oyster aquaculture, shellfish growers and scientists in California have partnered together to conduct comparative, multi-estuary farm trials of discrete Pacific oyster (Crassostrea gigas) lineages. In this thesis we investigate how the more recently imported Midori lineage performs compared to the historically used Miyagi lineage, as well as a Hybrid (Midori x Miyagi) lineage. As part of a 7-month long field study from April-November of 2024 in Morro Bay and Tomales Bay, California, we evaluated …

The Effect Of Specialty Malt On Dry-Hopping, Alexander Kivela

Master's Theses

Dry-Hopping is a modern and ever-increasing method to add hoppy flavors to beer. This is typically seen in pale ales and India Pale Ales (IPA’s). Most research has investigated the effect of dry-hopping only using pale malt, whereas most breweries used specialty malts to create a malty backbone to their beer.

The objectives of this research were to analyze the impact of specialty malts and their concentration on the efficacy of hop flavor and extraction, determined via gas chromatography and sensory analysis. Gas chromatography analysis was modeled after the ASBC Method Beer-48. Sensory analysis was performed via the 15cm line …

Effects Of Variable Light On Sexual Competition In Kelp Species, Jaycee Lanza

Master's Theses

As foundation species, kelps significantly influence the structure and composition of their surrounding habitat by modifying environmental conditions, including light levels, currents, nutrient availability, sedimentation, and seawater chemistry. Light, in particular, is a critical resource that varies greatly within kelp forests, affecting kelp reproductive processes such as gametogenesis, fertilization, and recruitment, which are vital to population persistence. Biological factors, such as density-dependent competition for resources and sexual competition with other kelps, can also affect such processes. To understand how environmental variables influence kelp populations, it is crucial to recognize their combined effects. This study investigated the impacts of light levels …

Evaluating Fungicide Programs For Grapevine Disease Management And Fungicide Sensitivity Monitoring, Abraham Ahumada

Master's Theses

Grapevine diseases, such as powdery mildew and Botrytis bunch rot, require repeated fungicide applications to maintain fruit quality and reduce yield losses. However, fungicide performance can vary among products, application programs, disease pressure, and pathogen sensitivity. This thesis evaluated fungicide programs for control of powdery mildew in ‘Chardonnay’ grapes and assessed fungicide sensitivity of Botrytis cinerea isolates collected from California vineyards.

Powdery mildew, caused by the fungal pathogen Erysiphe necator, is a major threat to the production of Vitis vinifera grapes worldwide. Because powdery mildew management relies heavily on fungicide applications, field evaluations are needed to compare the efficacy …

Evaluating The Impact Of Region, Vintage, And Carbon Dioxide-Based Winemaking Techniques On Wine Quality Of Mediterranean Varietals, Coleman R. Imrisek

Master's Theses

Changing Vitis vinifera ripening patterns as a result of increasing climate variability has provided challenges against the production of wines with a balanced sensory profile, with adequate acidity, color, aroma, and texture. This thesis aimed to evaluate the ripening patterns and wine profiles of potentially climate-adaptive Mediterranean varietals in two different California Central Coast climates. Additionally, different carbon-dioxide based winemaking techniques were also assessed. Viognier and Grenache Noir grapes were sourced from the warmer, diurnal Paso Robles AVA and the cooler, marine Santa Maria AVA during the 2024 and 2025 growing seasons, with Syrah and Grenache Blanc grapes being only …

City Farm Slo: A Case Study Of Nonprofit Regenerative Agriculture, Carver Tunnell

Master's Theses

The focus of this thesis is to create a case study on City Farm SLO, a nonprofit based in San Luis Obispo, California, that has engaged in education and regenerative agriculture on City owned land since 2013. This case study is intended for use in undergraduate agribusiness and natural resource management courses, to encourage thoughtful discussion surrounding nonprofit and regenerative agricultural systems. The case presents the nonprofit at a time of relative success, having recently secured a lease renewal, extending stewardship 40 years into the future. However, the reliance on grants and donations threatens the security of the operation going …

Independent And Combined Effects Of Early-Life Iron Deficiency And Antibiotic Exposure On Growth And Hematological Outcomes In A Piglet Model, Ginger M. Fitzpatrick

Master's Theses

Iron deficiency (ID) affects over 2 billion individuals globally. Children under 5 are at increased risk of ID due to rapid growth and are especially vulnerable to its negative consequences because of iron’s essential role in cognitive development and immune maturation. ID is the leading cause of iron deficiency anemia (IDA), with IDA affecting approximately 40% of children in this age group. Antibiotic (abx) exposure is also prevalent during early life and may disrupt growth and through gut dysbiosis, with increasing use posing additional risk in younger populations. Geographically, there is overlap in regions with high anemia prevalence and those …

Large Scale Kmer-Based Proteomic Analysis: An Application Towards Evolutionary Constraint Discovery, Matthew Chak

Master's Theses

Large protein databases now make it possible to study short peptides across natural protein sequence space at unprecedented scale, but exhaustively counting k-mers across billions of protein sequences remains computationally difficult. This thesis develops an exact amino-acid k-mer counting method based on direct addressing, in which fixed-length amino-acid strings are encoded as base-20 integers and updated with a sliding-window recurrence. By avoiding key storage and collision resolution, this approach removes overhead inherent to hash-map-based methods when the k-mer space is sufficiently dense. A memory analysis shows when direct addressing is preferable to open-addressing hash tables, and expected-saturation calculations motivate its …

Exploring Regenerative Vegetable Systems On The Central Coast Of California, Una S. O'Connell

Master's Theses

As climate change and current agricultural practices place pressure on the long term sustainability and resilience of food production systems, there is growing interest in whether existing agricultural systems can adapt to maintain productivity while improving environmental outcomes.

This study evaluated the effects of regenerative versus standard organic vegetable production systems on yield, insect communities, and weed suppression across three field trials conducted on California's Central Coast. In addition, I collected baseline soil health data for all trials. Trials 1 and 2 were carried out at the Cal Poly San Luis Obispo Organic Farm using cabbage and broccoli as cash …

The Effects Of Maceration And Enzymes On The Chemical Characteristics Of Hard Apple Cider, Manou De Pelsmaeker

Master's Theses

The purpose of this study was to analyze the effects of maceration and pectinase enzymes on the base chemical, polyphenolic, and volatile characteristics of cider. The apples (Fuji) were milled and macerated for 0, 4, 12, 24, or 36 hours, both with and without an enzymatic pectinase addition. While base chemical characteristics such as sugar content and ABV were unaffected, the acidity of cider was influenced maceration and enzymes. Extended maceration time resulted in lower concentrations of malic acid, and enzymes resulted in a lower pH compared to the control. Polyphenols were extracted during maceration time, resulting in higher concentrations …

Sustainable Management Of Soilborne Pathogens In Strawberry Production Through Host Resistance And Sanitation Practices, Maria G. Alvarez Arredondo

Master's Theses

Strawberry production in California is significantly impacted by soilborne pathogens that reduce plant productivity and increase management costs. This research addressed management of these pathogens through two independent approaches: evaluation of host resistance in strawberry cultivars and assessment of sanitation practices for reducing pathogen movement between fields.

Macrophomina root rot, caused by Macrophomina phaseolina, was evaluated over two growing seasons (2024–2025 and 2025–2026) using field trials at California Polytechnic State University, San Luis Obispo. In Year 1, disease incidence varied widely among genotypes, with mortality ranging from 1.3% to 88.8% and an average mortality of 26.4%. Area under the …

Chemical And Sensory Consequences Of Oxidative And Reductive Handling Of White Wines, Amelia Pargellis

Master's Theses

In the 2024 and 2025 vintage four experiments were performed each with a different varietal, namely Albariño, Grenache blanc, Loureiro, and Vermentino. These experiments investigated the effects of hyperoxygenation, reductive winemaking techniques, while monitoring the oxidation-reduction potential.

Albariño grapes were made following two juice protocols, control/reductive (Reductive Control) and oxidative (HyOx). Reductive Control received antioxidants (50 ppm SO₂, 160 mg/L ascorbic acid) and CO₂ blanketing, and HyOx underwent hyperoxygenation at approximately 700 mL/L/h of air for two hours through a stainless-steel sparging stone with 10-µm pores. Juice was cold-settled and racked. Reductive Control juice was split into …

Movement And Space Use Of Weaned Northern Elephant Seal (Mirounga Angustirostris) Pups During Their First At-Sea Foraging Migration, Katie Saenger

Master's Theses

The northern elephant seal (Mirounga angustirostris) is a marine mammal known for engaging in long foraging migrations at sea. Adult male northern elephant seals follow pathways along the western coast of North America towards Alaska and adult female northern elephant seals follow pathways to open ocean in the North Pacific. However, there is little information on weaned northern elephant seal pup foraging behavior during their first foraging migration. This lack of knowledge is significant because northern elephant seals have a mortality rate of >50% in the first year. This project aimed to better understand the at-sea migratory movement …

Effects Of Irrigation And Nitrogen Management On Yield And Leaching Risk In Organic And Conventional Broccoli Fields, Shane Egerstrom

Master's Theses

Under regulatory pressures to reduce groundwater contamination by nitrate from fertilizer, such as those posed by the Central Coast Regional Water Quality Control Board’s Agricultural Order 4.0, a need exists to better understand interactions between irrigation and nitrogen (N) management. To increase N use efficiency (NUE), growers are encouraged to account for additional sources of N in their management plans, such as irrigation water N and preplant soil N. The availability of these N sources for plant uptake and how it is affected by other management conditions is not yet well documented. We conducted 6 field trials, 3 organic and …

Assessing Nitrogen Leaching Risk In Organic Vegetable Production, Megan Widle

Master's Theses

Nitrogen (N) leaching is the primary driver of groundwater contamination in agricultural regions. On California’s Central Coast, Agricultural Order 4.0 regulates this risk by constraining field-level N balances (N applied minus N removed). However, the assumption that unrecovered N is lost via leaching may not hold in organic and regenerative systems that promote soil organic matter accumulation. This study evaluated whether measured N leaching aligns with estimates derived from partial N budgets in organic systems, and whether management practices (intercrops, cover crops, and reduced tillage) can mitigate leaching risk. Four field trials were conducted to investigate N dynamics in organic …

Evaluating The Commercial Aquaculture Potential Of The Native Pacific Littleneck Clam (Leukoma Staminea) As A Climate Resilient Alternative To The Non-Native Manila Littleneck Clam (Ruditapes Philippinarum)., Skylar M. Wuelfing

Master's Theses

The California shellfish industry’s near-exclusive reliance on the non-native Manila littleneck clam (Ruditapes philippinarum) creates an economic vulnerability to climate-driven disturbances, which can cause mortality events that eradicate up to 80% of stocks. This singular reliance on an introduced species highlights a need for the evaluation of native alternatives like the Pacific littleneck clam (Leukoma staminea). Our goal was to assess the feasibility of using the native Pacific littleneck in commercial aquaculture by comparing their performance to the non-native Manila littlenecks across the following conditions: 1) a five-month field outplant trial at high and low intertidal …

Marine Heatwaves And Fish Reproduction: Endocrine Responses In The Eurythermal Sheepshead Minnow (Cyprinodon Variegatus), Isabel Villafuerte

Master's Theses

Marine heatwaves associated with climate change are increasing in frequency and severity, posing significant threats to fish populations in shallow habitats such as estuaries and salt marshes. Because temperature is a primary regulator of fish reproduction, understanding how heatwaves affect reproductive physiology is critical for anticipating the biological consequences of ongoing climate change for coastal fishes. Here we examined how simulated heatwave conditions affect the reproductive hypothalamic-pituitary-gonadal (HPG) endocrine axis in the estuarine sheepshead minnow (Cyprinodon variegatus), a eurythermal fish well suited to studying thermal stress responses in estuarine environments. Adult sheepshead minnows acclimated to a daily oscillating …

Effects Of Hot Water Dipping And Sub-Zero Saline Chilling On The Microbial Safety Of Broiler Carcasses And Recycled Chilling Water, Elen Zhu

Master's Theses

Broiler meat became the most widely consumed meat within the United States and across the world in 2019. The trend of increasing broiler consumption is expected to continue due to affordability, health benefits, and production efficiency. To meet the growing demand of broilers, a substantial number of birds need to be produced and processed while minimizing bacteria contamination, water consumption and wastewater generation.

In this study, the microbial safety (mesophilic aerobic bacteria, coliforms, and Escherichia coli) of broiler carcasses and post-chill water (red water) was assessed, using innovative processing techniques and red water recycling. A total of 144 broilers …

Evaluation Of Ultraviolet-C Light For Control Of Mites And Western Tarnished Plant Bug In Strawberry & Interactive Lethal Effects Of Common Strawberry Fungicides And Adjuvants On Phytoseiulus Persimilis, Colin T. Koubek

Master's Theses

California strawberry production relies heavily on chemical pesticides to manage arthropod pests and diseases, but pesticide resistance, regulatory pressure, and the need to conserve biological control agents have increased interest in alternative pest management tools. This thesis evaluated ultraviolet-C (UV-C) light as a nonchemical management tool for key strawberry arthropod pests and assessed the compatibility of common strawberry fungicides and adjuvants with the predatory mite Phytoseiulus persimilis Athias-Henriot. The first objective was to determine the ovicidal and lethal effects of UV-C light on Lygus hesperus Knight eggs and nymphs. Laboratory and field ovicide assays were conducted using UV-C doses relevant …

Structure And Diversity Of Play Behavior In Juvenile Belding's Ground Squirrels, Paul O'Driscoll Ii

Master's Theses

Play behavior is ubiquitous among juvenile mammals and can promote motor, social, and cognitive development, providing multiple adaptive benefits to young animals in some cases. The structure of play can be linked to the benefits it confers on individuals. I evaluated the structure of play in juvenile Belding’s ground squirrels (Urocitellus beldingi), a species for which multiple adaptive benefits of play have been identified. I compared juvenile play in U. beldingi to adult sexual and aggressive behavior to determine and classify similarities between juvenile play and adult behavior. I evaluated diversity in the behaviors expressed during play interactions and diversity …

Investigating Cryptic Diversity In The Hawaiian Endemic Plant, Psychotria Mariniana (Rubiaceae), Uyen Thi Hoang Nguyen

Master's Theses

Islands, with their isolation and steep environmental gradients, serve as natural laboratories for studying speciation. Molecular phylogenetic and population genetic methods utilizing Next-Generation Sequencing (NGS) have revolutionized our ability to document patterns of genetic divergence and diversity. Cryptic diversity, genetically distinct populations that were previously unrecognized as unique, and cryptic speciation, where divergent genetic populations may be deserving of status as unique species, have been observed in many taxa. The Hawaiian Islands provide an ideal setting for studying divergence and speciation due to their extreme isolation, known ages, and volcanic origin. Previous work has investigated the evolutionary relationships of the …

Examining The Ligands, Location, And Function Of Toll-Like Receptor 10, Kiefer Keanu Tam

Master's Theses

Toll-like receptors are a class of innate immune pattern recognition receptors that detect pathogen-associated molecular patterns and regulate downstream inflammatory responses. Toll-like receptor 10 remains the only human TLR whose ligand specificity, cellular localization, and immunological function are not fully defined. Emerging evidence suggests that TLR10 may play an anti-inflammatory role and can heterodimerize with TLR2 to modulate immune signaling. Previous studies from our laboratory demonstrated that stimulation with heat-killed Mycobacterium tuberculosis promotes TLR2-TLR10 heterodimerization and trafficking to the cell surface. In this study, we expanded our ligand panel to include additional gram-positive bacteria, particularly anti-inflammatory probiotic species, to further …

Ecological And Nutritional Drivers Of Floral Fidelity In Wild Pollinators, Adelaide Elise Ergastolo

Master's Theses

Plants must receive pollen from the same species in order to successfully reproduce. For most flowering plants, the transfer of pollen occurs via animal pollinators while they forage on plants to obtain food. Therefore, the fidelity of pollinators to individual plant species during foraging trips is directly related to the amount of conspecific pollen plants receive. Low floral fidelity of pollinators can reduce plant reproductive success, which in turn has the potential to lower food resources for pollinators in the future. While many factors can potentially influence pollinator floral fidelity, several important ones may be the nutritional resources provided by …

Hormonal, Cytokinetic, And Skeletal Response To A Single Weighted Vest Exercise Treatment: A Pilot Study To Determine Weighted Vest “Rucking” Treatment For Osteoporosis In Post-Menopausal Women, Eleanor Pell

Master's Theses

Osteoporosis is characterized by a deteriorating of bone tissue leading to brittleness and increased fracture risk that affects both men and women as they age. Postmenopausal women are of particular interest due to high risk of declining bone density, a characteristic of this population. Treatments for osteoporosis range from menopause hormone therapy, bisphosphonates, biologics, nutritional changes, and exercise. Load bearing exercise interventions have shown effectiveness for stimulating bone growth, but many factors such as lack of access, motivation, self-confidence or knowledge, prevent long term compliance. “Weighted vest rucking” refers to a variation of rucking, which is a form of exercise …

Companion Parrot Vocal Learning And Reproduction Of Human Speech Sounds, Karla Vilches Castaño

Master's Theses

Vocal learning is rare among animals but is well developed in parrots, which can imitate novel sounds and, in captive settings, reproduce human speech. This study helps address a larger evolutionary question about vocal learning. Specifically, whether vocal learning ability is best understood as a single generalized trait or as a multi-dimensional system in which different acoustic features can be learned and reproduced with varying degrees of fidelity. This thesis quantifies how closely companion parrots match their human tutors across three acoustic dimensions (spectrographic structure, intensity contour, and pitch contour) and tests whether mimicry accuracy varies among individuals, differs between …

Investigating The Taxonomic Uncertainties Of Potentilla Rupincola, Natalie Elizabeth Hieber

Master's Theses

Landscape stewardship is an integral role for land managers that becomes more important when rare or endangered species occur within managed areas. Conservation across the landscape is a primary concern for land managers, but resources allocated for conservation can be limited due to many competing goals. Taxonomic uncertainty surrounding rare and endangered taxa, particularly plant taxa, that have historically been classified solely using morphological features further complicates conservation planning. One such taxon is Potentilla rupincola, a rare plant endemic to the eastern Rocky Mountains in Colorado. For over a century, botanists have debated whether P. rupincola is a distinct species …