Thesis and Dissertation Announcements

Thesis Defense

Mussel and Fish Assemblages Within Off-Channel Water Bodies of the Sabine and Neches Rivers

Major Advisor: Dr. Timothy H. Bonner, Department of Biology and The Meadows Center for Water and the Environment, Texas State University

Committee Members:

• Dr. Benjamin Schwartz, Department of Biology, Texas State University
• Dr. Charles Randklev, Texas A&M Natural Resources Institute, Texas A&M University

Abstract: Off-channel water bodies are predominantly lentic areas within the floodplain of riverine systems including adventitious streams and oxbow lakes. In the past, off-channel water bodies were largely ignored as habitats for riverine mussels and fishes based on the general perception of off-channel water bodies having poor water quality (e.g., low dissolved oxygen) and supporting only tolerant species. With increasing efforts by federal, state, and private organizations to assess population status of imperiled riverine species, there is a need to document all available habitats for more complete assessments of species occurrences and abundances within riverine systems. Objectives of this study were to quantify occurrences and abundances of mussels and fishes, to describe water quality and environmental variables, and to relate aquatic biota occurrences and abundances to reach effects (i.e., upper basin, lower basin) and system type effects (i.e., lotic, lentic) among 20 off-channel water bodies located within the Neches River and Sabine River basin of Texas between 2022 and 2025. Twenty seven species of mussels (N = 3,812) and 71 species of fishes (N = 25,480) were recorded from the 20 off channel water bodies. Most abundant mussel species were Glebula rotundata (26% in relative abundance), Quadrula quadrula (17%), and Quadrula nobilis (17%). Most abundant fish species were Dorosoma petenense (22%), Alburnops texanus (8.4%), Lepomis macrochirus (6.8%), Labidesthes (6.2%), and Pimephales vigilax (5.1%). Mussel assemblages and fish assemblages differed by reach with greater proportions of mussels with opportunistic life history strategies and lentic fishes found in upper reaches. Greater proportions of mussels with equilibrium life history strategies and lotic fishes were found in the lower reaches. In addition, off-channel water bodies classified as lotic systems (e.g., adventitious streams, oxbows running parallel to river mainstem) consisted of greater proportions of mussels with equilibrium life history strategies and lotic fishes than in off channel water bodies classified as lentic systems. Water quality variables indicated moderate levels of water quality (e.g., dissolved oxygen: 4.1-6.3 mg/l), although one time sampling during summer months was not sufficient seasonal variability in water quality. Overall, off-channel water bodies within the Neches and Sabine rivers of Texas supported a diverse community of aquatic organisms, similar to those (e.g., billabongs, fadamas, resacas) reported globally, and contributed to the biodiversity within river mainstems.

Bio: Caleb's appreciation for the outdoors began with hunting and fishing the woods and river bottoms of Northeast Texas. After earning an A.S. degree at Tyler Junior College, he transferred to Texas State University earning a B.S. degree in Wildlife Biology where his interest in the field of aquatic resources grew under the mentorship of Dr. Timothy Bonner. After graduating, Caleb hopes to continue learning and working in various freshwater rivers and streams.

Dissertation Proposal Defense

Shifting Environmental Community Behaviors Through the Use of an Education Intervention

Major Advisor: Kristy Daniel

Committee Members: 

• Leila Siciliano-Martina
• Derrick Taff
• Carrie-Jo Bucklin
• Merritt Drewery

Zoom Link: https://txstate.zoom.us/j/84149149772

Abstract: Interactive environmental education opportunities can boost one's interest in science. Engaging in meaningful outdoor activities can also promote pro-environmental behaviors among outdoor recreationists and science learners of all ages. As anthropogenic forces create strains on natural spaces, opportunities that allow visitors to connect with and learn about nature are crucial in maintaining the longevity of natural areas for communities to enjoy. A notable increase in people's investment in outdoor activities has resulted in an influx of visitors to outdoor spaces and recreational areas. Engaging with nature is crucial for human development, thus the trend of increased visitation is highly encouraging for community well-being. While spending time in nature can have positive cognitive, educational, and health benefits, increased outdoor traffic can create a negative impact on green spaces and the species that inhabit them. Common acts of trail degradation that contribute to this impact include the loss of soils and flora due to visitors venturing off-trail, water contamination due to fecal matter introduction, and wildlife disturbances. Further, when an outdoor area is visibly degraded, visitors may be less inclined to utilize the space, viewing these negative recreational impacts as intolerable. A balance must be struck between public usage and intentional conservation of natural resources. If stakeholders, such as land managers, day hikers, and other community members, treat outdoor green spaces mindfully through practices like those of Leave No Trace, degradation of the resources may be reduced. To encourage one to care for the natural world, we must first understand the factors that might motivate pro-environmental behaviors, such as environmental awareness, appreciation of nature, connectedness to place, and stewardship mindsets. Informal science experiences can engage learners by providing meaningful and relevant lessons in a hands-on, low-stakes environment. Immersive, place-based environmental education that connects content with participants' lived experiences may be key in shifting environmental attitudes and changing environmentally damaging community behaviors. Integrating authentic opportunities for scientific inquiry and data collection encourages participants to engage with nature while practicing pro-environmental behaviors.

Bio: Carolyn Jess holds her B.S. in environmental science from Sam Houston State University and a M.S. in Biology from Texas State University in 2024. While in the Daniel Biology Education Research Group and Texas Master Naturalist Program, she has had the opportunity to teach local families about nature and science topics through the Research Rangers program. Carolyn has a passion for wildlife conservation and hopes that through her work, she may teach others about San Marcos' natural spaces and inspire responsible treatment of these places.

Thesis Defense

Ribbiting stuff: Effects of environmental conditions on coping capacity, growth, and behavior in larval anurans

Major Advisor: Dr. Caitlin Gabor, Department of Biology, Texas State University

Committee Members:

• Dr. Andrea Aspbury, Department of Biology, Texas State University
• Dr. Emily Powell, Department of Biology, Texas State University

Zoom Link: https://txstate.zoom.us/j/87879723582pwd=fqXhj5sLg9scbhVsmfb071F9kTEcXa.1

Meeting ID: 878 7972 3582 Passcode: tadpoles

Abstract: Amphibians have biphasic life cycles and permeable skin that render them particularly vulnerable to shifts in both terrestrial and aquatic environments. Therefore, evaluating their fitness can determine habitat quality and provide early warnings of ecosystem stress. Amphibians exhibit plasticity and adjust their life-history traits, behavior, and morphology to cope with dynamic environmental conditions, but the anthropogenic increase in unpredictable events such as extreme weather and habitat loss/modification may exceed their coping capacity. I conducted two studies to determine effects of anthropogenically-driven environmental stressors on growth, development, activity, and coping capacity in two native Texas anurans. I tested the hypothesis that chronic exposure to environmental stressors disrupts larval development and reduces coping capacity by collecting urban-tolerant Gulf coast toad (Incilius nebulifer) tadpoles and randomly assigning each to one of five treatment groups: (1) cool/wet (control), (2) cool/dry, (3) hot/wet, (4) hot/dry, or (5) unpredictable variation of these conditions. I collected baseline waterborne corticosterone (CORT) samples on day 8, and baseline-stress recovery CORT samples on day 14 from both tadpoles and metamorphs. Baseline corticosterone in the unpredictable group was marginally elevated on day 8, suggesting unpredictability may serve as its own stressor, but by day 14 there were no significant differences in tadpole CORT. Metamorphs from both heat treatments (hot/wet and hot/dry), however, showed significantly higher CORT release rates compared to the control group, suggesting that negative latent effects on coping capacity carry over from the larval environment, even in an urban-tolerant species. I tested the hypothesis that watershed urbanization disrupts natural behaviors and reduces organism fitness by collecting urban-tolerant Gulf coast toad (I. nebulifer) tadpoles as well as Leopard frog (Rana berlandieri) tadpoles from seven sites that varied in urbanization, habitat complexity, and water quality, and recorded their time spent moving and hiding before and after exposure to a chemical predator cue. I found that habitat complexity and water quality were significantly negatively correlated with watershed urbanization, and R. berlandieri tadpoles from urban sites moved significantly less and were significantly smaller than those from rural sites, suggesting that urbanization may affect foraging success and overall fitness in R. berlandieri. I found no significant effect of urbanization on I. nebulifer tadpole behavior or size. Overall, my findings show that exposure to heat in the larval environment reduces coping capacity after metamorphosis in an urban-tolerant toad and suggests that urbanization degrades aquatic habitat quality and affects the natural behavior and fitness of R. berlandieri.

Bio: Jessie grew up in Austin, Texas, where she developed a passion for animals and conservation at an early age. She has always been especially drawn to the water, with a deep love for rivers, oceans, and other aquatic ecosystems that inspires both her work and hobbies. She graduated from Texas State University in 2022 with a BS in Geography/Environmental Studies and a BA in Spanish before returning to Texas State in 2024 to pursue her master's degree.

Thesis Defense

Assessing Fall Bat Activity in Texas: Implications of Wind Energy, White-Nose Syndrome, and Ultrasonic Deterrent Strategies

Major Advisor: Dr. Sarah Fritts

Committee Members:

• Dr. Shilo Felton
• Dr. Clay Green
• Dr. Anica Lee

Zoom Link: https://txstate.zoom.us/j/88591844610pwd=MwwaMBMLhKpedXLaoxJRF9xA4mfH38.1

Meeting ID: 974 485 6261 Passcode: 792006

Abstract: Bats serve as keystone species within ecosystems, fulfilling essential ecological functions including insect predation, plant pollination, and seed dispersal. Migratory tree bats: hoary (Lasiurus cinereus; LACI), eastern red (L. borealis; LABO), and silver-haired (Lasionycteris noctivagans; LANO), face significant threats during migration, resulting in substantial fatalities at North American wind energy facilities. Hibernating species, including cave myotis (Myotis velifer; MYVE) and tricolored bat (Perimyotis subflavus; PESU), while less impacted by wind energy, remain threatened by the westward spread of white-nose syndrome. To better understand environmental drivers of activity for these species and inform mitigation strategies, I conducted two studies. My first study assessed multiple environmental predictors of acoustic bat activity during fall across 48 sites in Texas, sampled over six four-day periods across three years using SM4BAT-FS detectors. The strongest predictor across most species was minimum daily temperature (TMIN), except for REDS. Land cover associations and effect sizes varied by species and spatial scale. For REDS, I pooled acoustic detections of LABO, western red (L. blossevillii; LABL), and Seminole bats (L. seminolus; LASE), and temperature effects remained competitive, while longitude exhibited the largest effect size among all top-performing models. My second study assessed the effectiveness of the MIDÉ ultrasonic deterrent at three pond sites in Hays County, Texas, across nine deterrent trials in September 2024. Using two SM4BAT-FS detectors and an AXIS 1942-E thermal camera, I assessed bat occupancy (via video detections and acoustic passes) within the treatment space for six control and treatment periods. Overall, the deterrent did not result in a significant reduction in bat activity, though effectiveness varied considerably across pond sites. Overall, my findings highlight the need for species-specific mitigation strategies that integrate temperature, land cover, and temporal variables to aid in the conservation of bat populations affected by wind energy operations and white-nose syndrome.

Bio: Cerise is a Georgia native with a strong passion for wildlife conservation and endangered species protection. She earned her bachelor' s degree in Wildlife, Fisheries, and Aquaculture with a concentration in Conservation Biology from Mississippi State University. Her experience includes wildlife research using drone-based survey methods, aquaculture management work on Double-crested cormorants (Nannopterum auritum) with the United States Department of Agriculture, and surveying species of concern such as northern long-eared bats (Myotis septentrionalis), oldfield mice (Peromyscus polionotus), and eastern spotted skunks (Spilogale putorius) as a Natural Resource Specialist with the Mississippi Department of Wildlife, Fisheries, and Parks. Outside of research, you can find her hiking, reading, thrifting, crafting, or binging the latest Netflix series. She looks forward to continuing her career in wildlife conservation and research and hopes to inspire more underrepresented students to pursue careers in the field.

Dissertation Proposal Defense

Identifying Novel Oncogenic Differentiation-blocking Genes from Human Druggable Receptome in Neuroblastoma Cells

Major Advisor: Liqin Du

Committee Members:

• Mar Huertas
• Peggy Biga
• Snezna Rogelj
• Tamer Saad Kaoud

Zoom: https://txstate.zoom.us/j/85862773868pwd=PylaPsOdiybiCdBwfQr0tqtnBHxAEN.1

Meeting ID: 858 6277 3868, Passcode: 961195

Abstract: Neuroblastoma is the most common extracranial solid tumor in children and a major cause of pediatric cancer related deaths. High-risk neuroblastoma is often characterized by poor differentiation, resistance to therapy, and unfavorable clinical outcomes. Differentiation therapy, such as retinoic acid treatment, has shown clinical benefit by promoting tumor cell maturation, but the molecular mechanisms that block differentiation remain poorly understood, limiting the development of more effective targeted therapies. This research project aims to identify key receptor proteins that act as molecular barriers to neuroblastoma cell differentiation and to determine whether pharmacological inhibition of these receptors can restore differentiation and suppress tumor growth. By focusing on receptor-driven signaling pathways within the human druggable receptome, the study seeks to uncover critical regulators that maintain neuroblastoma cells in an undifferentiated and proliferative state. The project integrates high-throughput functional screening with system-level network analysis to identify candidate receptor genes involved in neuronal differentiation and cell proliferation. These candidates are further explored through signaling pathway and interaction network analyses, along with microRNA-based regulatory studies, to reveal mechanisms underlying differentiation control in neuroblastoma. A key translational component of this research involves evaluating FDA-approved and clinically advanced small-molecule inhibitors targeting the identified receptors. By assessing both differentiation induction and cell viability, the study aims to prioritize compounds that promote differentiation at non-toxic concentrations. This drug repurposing strategy offers a rapid and cost-effective pathway to identify promising therapeutic candidates. Overall, this research has the potential to advance understanding of neuroblastoma biology and contribute to the development of safer, more effective differentiation-based therapies for children with high-risk neuroblastoma

Bio: Saika Anne is a PhD researcher in Aquatic Resources and Integrative Biology at Texas State University, USA. Her interdisciplinary background in agriculture, genetics, and biology has shaped her interest in understanding complex biological processes. Her research interests include molecular biology, environmental stress responses, and integrative biological systems. She aims to pursue a career in academia and foster interdisciplinary collaboration to address biological and environmental challenges.

Dissertation Proposal Defense

Spatio-temporal dynamics of tropical mammalian carnivores: functional traits, niche conservatism and human impacts

Major Advisor:  Dr. Iván Castro-Arellano

Committee Members:

• Dr. Leila Siciliano-Martina
• Dr. Michael Clay Green
• Dr. Juliana Bedoya-Durán
• Dr. José F. González-Maya

Zoom: https://txstate.zoom.us/j/85151169049pwd=eK2TaYbopMOGsAwyYdgM6gBBm35Bca.1

Meeting ID: 851 5116 9049; Passcode: 843133 

Abstract: The mechanisms structuring mammalian carnivore assemblages (order Carnivora) remain incompletely understood, limiting biodiversity conservation efforts. Resource utilization, constrained by biomechanical and physiological factors, is central to these dynamics and linked to niche dimensions such as microhabitat, diet, and time. Among these, time represents a critical axis that can be partitioned to reduce resource overlap and competition. Functional traits, including body size and dental morphology, influence energetic requirements, prey size limits, and degrees of carnivory specialization, thereby facilitating trophic niche differentiation. Coexistence is further promoted through variation in hunting strategies, activity patterns, and habitat use. Analytical tools such as the Rosario algorithm enhance assessments of temporal overlap, yet applications remain limited. Comparative evidence indicates that activity patterns differ between island and continental species, reflecting adaptive responses to distinct ecological pressures. Anthropogenic disturbances, including fragmentation, urbanization, and apex predator loss disrupt temporal partitioning, intensify competition, and destabilize communities. My dissertation addresses critical gaps in understanding how mammalian carnivores use time as a niche axis across continental and island ecosystems under natural and human-modified conditions. Specifically, it aims to: (1) test whether diel activity patterns exhibit temporal niche conservatism between islands and continents; (2) examine interactions between spatio-temporal overlap and functional traits such as body size and dentition; and (3) evaluate how habitat fragmentation reshapes temporal partitioning and coexistence strategies. Chapter 1 updates the Rosario algorithm for cyclical pattern analysis using R. Chapter 2 investigates spatio-temporal partitioning among carnivore species, the influence of functional traits on activity patterns, and the role of temporal niche conservatism across continental and island ecosystems. Chapter 3 evaluates the effects of habitat fragmentation on carnivore activity patterns in Colombia, comparing large-scale patterns (continent vs. island) with local-scale dynamics (forest remnants functioning as islands within a transformed matrix). By integrating ecological theory, functional morphology, landscape ecology, and advanced analytical tools, my research aims to elucidate mechanisms driving mammalian carnivore assemblages’ structure and providing insights for biodiversity conservation in increasingly human-modified landscapes.

Bio: Tatiana is a wildlife biologist from Colombia. Growing up in a charming small town in the middle of the Colombian Andean mountains has fueled her interest in wildlife studies. She holds a bachelor’s degree in biology from Universidad del Quindío (2016) and a master's degree from Universidad del Valle (2024). Her research focuses on the ecology, taxonomy and conservation of tropical mammals. After completing her degree, she wants to remain in academia and will encourage collaboration between NGOs, local communities, and universities in Colombia with the goal of developing targeted conservation strategies for tropical ecosystems.