Theses
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Item Characterization of the relationship between nitric oxide and serotonin in the formation of long-term memory in an invertebrate model(2024-05-03) Richards, Landrue C.; Mozzachiodi, Riccardo; Cammarata, Kirk; Omoruyi, FelixLearning is a process by which all animals modify their behaviors to ensure increased fitness. In the mollusk Aplysia, long-term sensitization (LTS) serves as a prime example of this learning process, where defensive behaviors, such as the tail-siphon withdrawal reflex (TSWR), are heightened for prolonged periods as a result of repeated exposure to noxious stimuli, showcasing the organism's adaptation to experience. This behavioral plasticity is paralleled by neurophysiological changes, including the long-term increase in excitability (LTIE) of tail sensory neurons (TSNs), serving as neural correlates of LTS and providing a window into the cellular and molecular mechanisms sustaining this form of memory. The neurotransmitter serotonin (5-HT) is known to mediate LTS formation in Aplysia. 5-HT exposure alone can also induce LTS in vivo as well as LTIE in vitro. However, recent findings indicate that the neurotransmitter nitric oxide (NO) is also necessary for LTS formation. However, it is not known where exactly NO lies in the chemical pathway concerning 5-HT. Therefore, the purpose of this project was to investigate NO’s involvement in long-term memory formation in an invertebrate model. More specifically, the way two chemical messengers, NO and 5-HT, work in the brain. Our findings reveal that NO likely functions downstream of 5-HT, as evidenced by the blockage of in vivo LTS formation by L-NAME, an NO inhibitor, despite the presence of 5-HT. Further, we confirm that NO's role is not significant in in vitro long-term increase in excitability (LTIE), reinforcing its specific importance in LTS. In conclusion, our study significantly advances the understanding of LTS in Aplysia by detailing the interactions between NO and 5-HT. Our findings not only advance our understanding of LTS but also open new avenues for memory and learning research, emphasizing the complexity of neurochemical interactions in learning processes.Item Metadiscourse markers in L2 source-based informative essays: An analysis of texts written by L2 undergraduate students(2024-04-22) Pham, Dang Thuy Anh; Doolan, Stephen M; Andrews, Christopher; Pina, ManuelImproving writing skills is considered essential for L2 students, especially in academic settings, reflecting part of the overall language proficiency (Teng et al., 2022). L2 writing complexity, influenced by internal and external factors, inspires the use of metadiscourse markers as valuable tools for self-reflection and communication (Casanave, 2017; Teng & Zhang, 2018; Hyland, 2004). Prior research has explored metadiscourse markers in L1 writing, contributing to proficiency improvements (Aull, 2019; Hong & Cao, 2014; Yoon, 2021; Lee & Deakin, 2016), within college students’ writing (Bax et al., 2019; Huh & Lee, 2016; Ramoroka, 2017), graduate theses and dissertations (Hussein et al., 2018; Ozdemir & Longo, 2014), and research articles and book reviews (Abdi, 2011; Gillaerts & Van de Velde, 2010). However, there is a limited examination of how these markers function in L2 college students’ source-based type of writing. This study, based on Hyland’s framework (2005), analyzes data from L2 college students’ informative source-based writing. Particularly, I will look at a total of 36 L2 informative, source-based, First-year writing program essays, with 16 essays in the higher-rated category (5258 words) and 20 essays in the lower-rated category (5169 words), collected from L2 students within the First-year Composition programs from two universities in the US. The essays were analyzed by a computerized program to produce comprehensive concordance lists of markers alongside essential information about the prompts and the authors, enabling analyses to explore the diversity distribution and specific functions that metadiscourse markers serve in these essays. The findings reveal that higher-rated essays displayed a broader spectrum of metadiscourse features, fostering connections within essays and enhancing communication with readers. Furthermore, while engagement markers, particularly imperative directive features, were preferred by students from both proficiency groups to establish a direct relationship with readers, various subtypes of hedges and boosters also stand out, especially in a higher-rated group, as productive tools for expressing specific shades of certainty and commitment. Lastly, highly frequent usage of self-mentions in lower-rated essays can signal students’ preference towards expressing ideas from personal perspectives and possible struggles in critically synthesizing source texts into statements. In summary, understanding metadiscourse markers used in L2 writing helps students with tools to enhance writing communication, provide insights for teachers in improving teaching approaches, and inspire further scholarly discourse.Item Group consensus with the Analytical Hierarchy Process using singular value decomposition and methods for tensors(2024-05-03) Nava, Rebecca Lee Ann; Tintera, George; Vasilyeva, Maria; Mallikarjunaiah, S. M.The Analytical Hierarchy Process (AHP), created by Saaty [12, 13, 15, 14], has been used over the last few decades to enhance the decision making process in several fields of study. Such fields include medicine, computer science, education, and business. AHP uses pairwise comparison matrices (PCM), where the diagonal entries 𝑎𝑖𝑖 = 1 and for all other entries 𝑎𝑖𝑗, 𝑎𝑗𝑖 = 1/𝑎𝑖𝑗. Consistent pairwise matrices will satisfy the requirements of a PCM, and will also satisfy the consistent property of 𝑎𝑖𝑘 = 𝑎𝑖𝑗 ×𝑎𝑗𝑘. Pairwise comparison matrices that are inconsistent may not necessarily be of rank one and will not satisfy the consistent property. Any inconsistent PCM will have an approximate consistent version. Solving a PCM means determining the individual weights of the criteria. Saaty’s Eigenvector method can be used on consistent PCMs to determine the weight vector, but is unreliable for those that are inconsistent. Gass and Rapscak [10] proposed a new method of determining weights through SVD, which is applicable to pairwise comparison matrices of varying consistency. This thesis will focus on creating tensors from pairwise comparison matrices. The tensor slices or faces will each be a pairwise comparison matrix. Each slice can be compared to an individual’s relative preference, and the tensor will group all preferences together. Ideally, the individuals will be making a decision on the same topic, but their ”best” choice may not be the same as the other group members. Once the preferences are grouped together, the method of unfolding will be used to further study the tensor. Saaty’s geometric mean method for group consensus will also be observed and compared to the method of unfolding. There are conditions a method must meet to be used for determining group consensus. These conditions will be observed and proven for unfolding. Afterwards, some calculations will be made to compare the methods and understand their differences.Item Diffusive transport and coral calcification: A comparative study of branching and plating morphologies under ocean acidification(2024-05-03) Herrera, Bryanna Noelle; Bahr, Keisha D.; Bogucki, Darek; Hu, XinpingCorals are sessile animals that are subject to their environment and have various colony morphologies that influence their diffusive boundary layer, a thin layer of fluid surrounding the coral surface. Boundary layer dynamics are crucial for corals to acquire nutrients from the environment, supporting essential functions like calcification. However, we lack knowledge regarding individual and species-specific responses to changes in water column conditions and how these changes can affect boundary layer dynamics and, consequently, calcification. Therefore, the purpose of this study is to incorporate engineering concepts to investigate drivers and connections between the physical and chemical controls on coral calcification in current and future predicted ocean acidification (OA) conditions. The Hawaiian rice coral, Montipora capitata, is a polymorphic coral with multiple growth forms, including branching, plating, and encrusting. Six branching and plating M. capitata colonies were collected, and three of each morphology were exposed to two different water chemistry conditions for two weeks. Microsensor profiles were conducted to measure boundary layer thickness and water chemistry changes, and a flume was designed and constructed to control water flow. The findings show that the plating morphology has a thicker boundary layer than the branching morphology at the site of primary photosynthesis. Moreover, at the site of primary photosynthesis, a significant difference in surface oxygen (O2) concentrations was observed between the two morphologies in ambient conditions, implying increased O2 efflux rates and coral productivity from a branching morphology.Item No humans here: Exploration in the digital age(2024-05-01) Grabko III, John L.; O'Malley, Ryan; Rote, Carey; Pena, Joe; Durham, JonathanNo Humans Here connects a lineage between landscape painters of the Hudson River School and Impressionists with 3D landscape renderings from artists of the early digital age at the turn of the millennium – work that conveyed an era of unbound creativity before dwindling as populated by more and more people over time. This transition diluted elements of exploration and curiosity through actions of curation, control, and exploitation - to the point that what once was, no longer remains. The initial magic, mystery and creativity of those early explorers and inhabitants in this digital age are now merely artifacts. As global exploration began to reach its limits by the mid 20th century, the advent of digital space opened new lands to cultivate and explore. Artists of the 90’s began using modeling programs, beginning with natural landscapes and architecture as a launchpad for creativity, akin to previous eras of landscape art – with particular comparisons to the Hudson River School. These early digital worlds were void of human inhabitants due to the practical nature of digital space itself – that humans do not exist directly within, rather we (currently) interact externally – or their presence is only alluded to because of technical limitations. Unlike early American landscape paintings, users of this new medium were unconstrained by romanticized realism or religious fervor, rather, they were unbound by the vastness of their own imaginations, and fantasy and science fiction literary influences of the 20th century such as J.R.R Tolkien (1892-1973) and William Gibson (b. 1948). Additionally, the use of light, color, and visual-distortion brushstrokes of Impressionist landscape painting parallels the pixelated, low-resolution imagery of the early digital age. As of this writing, humans do not physically exist within digital space but use it as a gateway for mental projection. Digital space exists outside of time itself – records of its early history still live on online, untouched and without decay, while also constantly evolving through the present. No Humans here pays homages to the creativity of early 90's digital landscapes through nostalgia and reimagining, while also questioning hope, loss, and entropy of our digital futures.Item A mental health literacy intervention to improve psychological treatment-seeking attitudes and intentions in African Americans(2024-05) Gipson-Washington, Raven Kye; Houlihan, Amy E.; Longley, Susan L.; Lauderdale, SeanAfrican Americans are disproportionately less likely to receive treatment for their mental illness(es) (39.4%) than their European American counterparts (52.4%). This is a public health problem. To confront this problem, it is necessary to address the issue of treatment-seeking. Typically, the first step in the treatment life-cycle is to decide to seek help. For African Americans, this decision is often complicated by a significant number of barriers to treatment, unique to the Black experience, including systemic-level barriers, cultural barriers, individual-level barriers, and psychological barriers. The present study addressed the psychological barriers. The primary aim of the study was to increase psychological help-seeking attitudes and intentions by increasing mental health literacy, reducing internalized stigma, and reducing the endorsement of Black strength schema. To do this, a single-session, online mental health literacy intervention, was developed specifically for African Americans: the Black Mental Health Education Program - Anxiety and Depression (BMHE-AD). The participants were randomly assigned to either the experimental group (culturally-relevant intervention) or the control group (non-culturally-relevant intervention). All participants demonstrated an increase in help-seeking attitudes, help-seeking intentions, depression literacy, and anxiety literacy. There was a decrease in internalized stigma and no change in the Black strength schema. There was no significant difference across conditions and no statistically significant mediation between participation in the culturally-relevant intervention and help-seeking attitudes and intentions.Item Temporal variation in sulfide intrusion in the seagrass Halodule wrightii(2024-05-03) Dalton, Natasha Alexandra; Larkin, Patrick; Abdulla, Hussain; Zhang, LinSeagrasses are productive ecosystems that form dense meadows in shallow marine waters. Anthropogenic disturbances, particularly nutrient enrichment, have caused the loss of 29% of seagrass meadows in the past century. Sulfide intrusion, a toxic byproduct of microbial processes in sediments, is known to be a significant stressor to seagrasses, leading to reduced photosynthesis, hindered growth, and even die-off. We conducted a nearly year-long study on sulfide intrusion in H. wrightii tissue, measuring d34S and total sulfur values in leaf, rhizome, and root tissues during the summer, fall, and spring seasons. We also investigated the relationship between these intrusion indicators and environmental factors known to affect them, such as sedimentary d34S, porewater H2S, total biomass, total organic content, and iron levels. While the levels of these factors varied across weeks and seasons, we found few significant correlations with intrusion. However, we did observe significant correlations between plant tissue d34S and total sulfur content (Rroots =-0.49, Rrhizome = -0.44), suggesting that sulfide intrusion contributes to total sulfur content in below-ground tissues. In general, it appears that the factors affecting sulfide intrusion are both subtle and complex. By exploring other variables and sampling sites, we may be able to uncover more information about these relationships.Item Evaluating habitat provision by restored intertidal and subtidal oyster reefs in St. Charles Bay, Texas(2024-05-02) Chapa, Neina; Pollack, Jennifer Beseres; Hollenbeck, Christopher; Olsen, ZacharyEstuarine habitats, such as Crassostrea virginica oyster reefs, are critical to the resilience of coastal environments and provide many ecosystem services. To address declining oyster populations, oyster reef restoration has become a widespread management strategy to recover and restore lost ecosystem functions and biodiversity. While traditional restoration practices in Texas have focused on subtidal oyster reefs to ameliorate harvest impacts, there is growing interest in restoring intertidal reefs to maximize habitat benefits. This study evaluates the development of oyster populations and epifaunal communities on concurrently restored intertidal and subtidal oyster reefs in St. Charles Bay, TX, USA. In May 2022, 2.4 ha of oyster reef complex were restored in intertidal (0.5 m depth) and subtidal (1.5 m depth) areas using recycled oyster shells. Epifaunal and oyster dynamics were measured on the restored reefs and nearby natural reference reefs for 12 months (epifauna) and 18 months (oysters) following restoration. Results indicate distinct timelines for oyster population and epifaunal community development: restored subtidal reefs progressed faster, reaching peak oyster densities of 2203 ind. m-2 and similar epifaunal community composition to natural reference within 6 months post- restoration. In contrast, intertidal reefs reached peak oyster densities of 390 ind. m-2 at 12 months post- restoration with dissimilar epifaunal community compositions compared to natural reefs. Spat recruitment to restored intertidal and restored subtidal reefs occurred immediately following restoration, and oysters grew rapidly during the first 3 months, averaging 0.97- 0.95 mm d-1. Submarket size oysters (25- 75 mm) were observed on both restored intertidal and restored subtidal reefs just 1 month after restoration, and market size oysters (≥ 76 mm) occurred on the restored subtidal reefs within 6 months. Large quantities of drift algae were deposited on the restored intertidal reefs in August 2022 and persisted for 4- 6 months, which may have affected oyster and epifaunal recruitment and growth. On restored subtidal reefs, epifaunal densities, biomass, diversity, and community composition became similar to natural reference reefs within 6 months following restoration. On restored intertidal reefs, although epifauna diversity became similar to natural reefs within 12 months, epifaunal community composition remained distinct throughout the 18-month study period. The findings of this study offer important insights into key differences in restored intertidal and subtidal oyster reef development, making it possible to evaluate the ecological tradeoffs of restoration approaches and inform future restoration efforts.Item Mapping oyster habitat quality in Matagorda Bay through remote sensing-derived water quality datasets(2024-05-03) Bygate, Meghan; Ahmed, Mohamed; Liu, Chuntao; Montagna, Paul; Murgulet, DorinaEvaluating oyster habitat quality is gaining importance as populations face drastic global declines. Oyster Habitat Suitability Index (HSI) models evaluate habitat quality. Environmental and water quality indicators (WQIs) generate these oyster HSIs. In this study, we extracted WQIs from remote sensing data from 2014 to 2023 (Chapter II), then utilized these WQIs alongside other physical variables to produce five oyster HSI models for Matagorda Bay (Chapter III). These oyster HSIs generated used salinity, turbidity, temperature, depth, and water velocity to depict habitat quality. Remote sensing datasets offer a unique opportunity to observe spatial and temporal trends in WQIs, such as chlorophyll-a, salinity, and turbidity, across various aquatic ecosystems. In this study, we used available in-situ WQI measurements (chlorophyll-a: 17, salinity: 478, and turbidity: 173) along with Landsat-8 surface reflectance data to examine the capability of empirical and machine learning (ML) models in retrieving these indicators over Matagorda Bay, Texas, between 2014 and 2023. Models with greatest performance were applied to generate datasets for each WQI from 2018 to 2023. Five oyster HSI models were then generated over Matagorda Bay on both monthly and annual scales from 2018 to 2023. Each model utilized five physical parameters (e.g., model inputs), including salinity, turbidity, water temperature, depth, and water velocity. The developed approach provides a reference context, a structured framework, and valuable insights for utilizing empirical and ML models and Landsat-8 data to retrieve WQIs over aquatic ecosystems. Additionally, oyster HSI models generated from this study suggests locations of optimal, moderate, and unsuitable habitat based on long-term water quality in Matagorda Bay.Item Women working overtime: The influence of the second shift discrepancy on relationship and life satisfaction(2024-04-19) Bennett, BrookEryn; Zaikman, Yuliana; Houlihan, Amy; Bartholomay, DanielThe second shift phenomenon can be described as the second unpaid shift of work performed by women after a full paid work shift. Women disproportionally perform more household work even when both men and women in a relationship perform the same working labor hours. With the utilization of Relationship Assessment Scale, Life Satisfaction Assessment, The Second Shift Scale, and Gender Role Stereotype Scale, we will be able to determine if the second shift is influenced by certain factors such as gender role attitudes, religiosity, political affiliation, gender, whether the couple has children, age of children, and relationship status (i.e., married, engaged, dating). We determine if the predictor values and the division of household labor influence relationship satisfaction and life satisfaction for each partner. Through various linear regression analyses, it was found that women who have (younger or older) children compared to women with no children had greater life satisfaction while women who had children predicted lower relationship satisfaction. Interestingly, couples who are not married had higher levels of second shift of household chores, and couples with higher levels of second shift emotional work led to lower women's life satisfaction. Past literature has not investigated the influence of incongruencies in actual versus aspiration second shift for partners on relationship satisfaction in the U.S; therefore, further analysis will focus on couples’ incongruencies of perceived second shift and how it influences men’s and women’s life and relationship satisfaction.Item Exploring the influence of built environment factors on COVID-19 vaccinatation uptake(2024-05-03) Abbasian, Ziba; Huang, Yuxia; Zhang, Hua; Jin, LeiThis study examines the interconnections between the built environment and vaccination uptake in Nueces County, Texas, through the applications of Ordinary Least Squares (OLS), Spatial Autoregressive (SAR), and Spatial Durbin Model (SDM) regressions. Focusing on an array of built environment factors—such as road density, road diversity, bus stop density, park density, traffic signal density, road connectivity, population density—and the Social Vulnerability Index (SVI) as a sociodemographic factor, the study aims to uncover how these elements influence the rates of both full and booster vaccinations. Data from the Nueces County Public Health District and OpenStreetMap were analyzed to identify significant spatial patterns and determinants affecting vaccination coverage. Key findings indicate that certain built environment attributes, notably road connectivity and park density, play a pivotal role in enhancing the vaccination uptake rates. Furthermore, the incorporation of SVI into the analysis highlights the critical nexus between social vulnerability and health disparity, emphasizing the need for targeted public health strategies. This research contributes to the broader discourse on the significance of integrating urban planning and public health efforts, proposing that well-considered urban design can be instrumental in improving vaccination rates and, by extension, community health outcomes. By analyzing the complex relationships between spatial factors and vaccination behaviors, this thesis not only enriches the existing literature but also lays the groundwork for future studies to incorporate a wider range of variables and employ more granular spatial analyses. Such advancements could provide insights into individual and community-level determinants of vaccination uptake, offering guidance for the development of more nuanced and effective public health interventions.Item Two-Species competition model with diffustion and harvesting: A numerical study(2023-12) Caro, Jasmin Tiana; Palaniappan, D.; Rao, B. Veena S.N.; Vasilyeva, Maria; Gaurdiola, JosePredicting well observed states in ecology such as co-existence, competitive exclusion of one competitor, and bi-stability is vital during multi-species competitions. Models that examine these aspects of living systems have extensive applications in the overlapping areas of applied mathematics, population ecology, invasion science, evolutionary biology, and economics. The present study investigated a twin species Lotka-Volterra competition system accommodating diffusion and harvesting environments – a scenario widely anticipated in mathematical ecology. Our mathematical setup converts the diffusion and harvesting incorporated physical model into a system of second order nonlinear partial differential equations (PDES) describing the competition of the two species in closed domains. A finite difference numerical scheme is developed to solve the nonlinear boundary value problem (BVP) with Neumann boundary conditions. We applied our model results to the case of Brown and Pink shrimp in southeastern Gulf of Campeche that compete for resources in Marine Protected Areas (MPAs). For this specific example, we computed theoretical results for the sustainable biomass yield due to the competition and the mobility in the presence of multiple fishing zones. Our numerical solutions reveal that the speed or mobility of species is critical for the design of MPAs to attain a maximum sustainable biomass yield. Additionally, the results indicate that harvesting rate is adjustable for larger number of MPAs along the coastal line for efficient fishing. Further, it is observed that a sustainable biomass can be achieved for low mobile species such as the brown and pink shrimps by having smaller MPAs and both the species can co-exist in Gulf of Campeche.Item Physiological assessment of common bottlenose dolphins (Tursiops truncatus) across a salinity gradient(2023-12) Guinn, Makayla; Orbach, Dara; Seemann, Frauke; Pollack, JenniferCommon bottlenose dolphins (Tursiops truncatus) are important bioindicators of ecosystem welfare and can inhabit environments with variable natural salinities. Anthropogenically-induced climate change exacerbates natural fluctuations in salinity and magnifies physiological imbalances in marine species. Bottlenose dolphins are well-suited model organisms to study the effects of environmental disturbances because they accumulate indices of stress in their blubber. Prolonged low salinity (< 10 ppt) exposure in dolphins elevates adrenal steroid hormones (i.e., aldosterone, cortisol) and promotes lesion development. However, the tolerances of and consequences for dolphins in hypersaline systems remain unknown. I assessed the physiological condition of three dolphin stocks in the Gulf of Mexico inhabiting areas of different natural salinities: Mississippi Sound, MS (0 – 30 ppt), Redfish Bay, TX ( 22 – 35 ppt), and Upper Laguna Madre, TX (37 + ppt). Steroid hormones were measured in remotely biopsied dolphin blubber using high-resolution liquid chromatography-mass spectrometry. Skin lesions were assessed using images of the dorsal fins and bodies of dolphins photographed from a research boat. There is a positive relationship between cortisol and salinity, indicating high salinity may impose physiological stress in dolphins. Testosterone concentrations in males are seasonal, with peaks in the fall and winter months. Progesterone levels in females were highest in the spring and summer and were indicative of gestation events. Skin lesions are most prominent on dolphins in the fall and winter, and a negative correlation between lesion prevalence and water temperature suggests cold water has a strong effect on epidermal integrity and lesion susceptibility in dolphins. I present here the first physiological assessment of free-ranging dolphins in a natural hypersaline bay. The dolphin health data collected from this research can help fill national data gaps for GoM dolphin stocks outlined by the National Oceanic and Atmospheric Administration, fill local data gaps for RB and ULM dolphin stocks, inform coastal communities of local marine ecosystem health and potential impact on human health by utilizing dolphins as bioindicators, and contribute to the understanding of how global climate change impacts the ability of marine organisms to adapt to highly variable environmental conditions. Additionally, this research will contribute to the planning of environmentally sustainable infrastructure (e.g., desalination plants) and promote environmental stewardship, ecotourism, and appreciation for natural resources.Item Distribution of polymer types in Matagorda Bay & biofilm presence on surface of plastic pollution: A study using attenuated total reflectance-Fourier Transform Infrared Spectroscopy and principal component analysis(2023-12) Ivy, Kiersten M; Abdulla, Hussain; Conkle, Jeremy; Olson, MarkGlobal plastic pollution presents significant environmental and economic challenges, exacerbated by mismanagement and low recycling rates. Studies have shown other pollutants like persistent organic pollutants (POPs) and heavy metals can sorb to plastic debris in aquatic ecosystems, making them more readily dispersed throughout ecosystems. This study (1) quantified the spatial and seasonal distribution of different plastic polymer types along the Matagorda Bay system, and (2) explored the nature of the biofilm form on these plastic debris and any correlation between biofilm type and polymer type throughout different seasons. This comprehensive study, the most extensive of its kind with over 3,000 samples, investigates the distribution of plastic polymers AND biofilm formation in the Matagorda and San Antonio Bays across three seasons in 2022. Attenuated total reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) along with Principal Component Analysis (PCA) was employed to identify polymer types and investigate biofilm formation on the collected samples. Polyethylene and polypropylene were the predominant polymer types observed across all sites and seasons. PCA suggested that biofilm was prevalent across all polymer types and seasons, and it is made mainly of extracellular polymer substances (EPS) that are rich in carbohydrates and proteins. Spectra integration showed a positive linear relationship between carbohydrate and protein biofilm components. This study not only provides a deeper understanding of biofilm roles in pollutant adsorption, but also introduces a novel, nondestructive approach for examining bacterial biofilms, paving the way for improved environmental management strategies.Item Macroinvertebrate communities and decomposition rates of leaf and stem litter in a Texas saltmarsh-mangrove ecotone(2023-12) McGuigan, Molly; Proffitt, C. Edward; Devlin, Donna J.; Montagna, Paul A.After an extreme freeze event in 2021 caused extensive mangrove mortality and widespread top-kill to surviving mangroves and salt marsh vegetation along much of the Texas coast, it produced a massive flush of dead leaf and stem material in the ensuing litterfall. I questioned if there was a difference in macroinvertebrate community composition in leaf and stem litter and litter decomposition rates between Avicennia germinans (L) L, the black mangrove, and Batis maritima L, a halophytic succulent forb. In a field experiment, I used mesh litter bags to either allow or exclude macroinvertebrates and found no difference in macroinvertebrate community composition between the two litter types, suggesting they are generalists within a mesohaline and hypersaline environment. Wetness level of bags varied from dry, partially damp, mostly damp, and wet, and was significant in determining community composition parameters, with mostly damp bags having the highest abundance, richness, and diversity of macroinvertebrates. However, wetness level was not significant in determining litter decomposition (k). I found that leaf and stem litter is rapidly colonized and decomposed at 2-weeks post placement and then faunal abundance and diversity decline after 2 weeks, suggesting litter serves as a temporary “oasis” for macroinvertebrates. There was no difference in litter decomposition rate between mesh sizes, implicating that colonization by macroinvertebrates does not have a significant effect on litter decomposition, and rather it is likely being affecting by other abiotic and biotic factors or a combination of both. This study was the first to quantify B. maritima litter decomposition, with a rate of 0.098 g day-1, as compared to A. germinans litter decomposition of 0.024 g day-1. This research should inform management decisions by coastal land managers and conservationists when making management decisions concerning small invertebrate use of and effects on litter as communities shift from herbaceous saltmarsh to woody mangrove and influence the food webs of which small invertebrates are an important component.Item Effect of observation on exhaustion and social physique anxiety(2023-12) Parikh, Vishwa Sameer; Davis, Liana; Snarr, Ronald; Ricard, RichardIntroduction: Exercising in a crowd could make some people more anxious regarding their body which can affect exercise performance (McCann et al., 2007; Gammage et al., 2009). A construct within anxiety, social physique anxiety (SPA) combines body image with social anxiety, by measuring the apprehension reported when one worries about others’ perception of one’s body structure (Hart et al., 1989). General anxiety has been found to be associated with fatigue (McCann et al., 2007), but whether crowd-related anxiety is also associated with more risk of fatigue is uncertain. Purpose Statement: This study examined the differences in exhaustion and SPA following exercising while being observed versus without observation. Methods: Fifteen recreationally active volunteers were recruited as participants. Exercise testing was performed in two different sessions through the cycling maximal oxygen consumption test, at fixed speed for each participant. SPA scoring was done using a nine-item questionnaire before and after each session. While one session of testing for everyone involved no recording, another included a recording device being set up. After each session, participants were requested to give their rate of perceived exertion (RPE) ratings. Repeated measure nonparametric test was used to analyze the differences in all scores between and within the two sessions. Results: Differences in each question of SPA were trivial to moderate. Large difference was observed for male participants’ respiratory exchange ratio (RER). Trivial differences were observed between the two sessions for time to exhaustion. Small negative correlations were noted between RPE and SPA and between SPA and time to exhaustion (TTE).Item Comparative statistical analysis of sea surface temperature time series modeling in the Gulf of Mexico(2023-12) Riba, Madison; Jin, Lei; Hu, Xinping; Guardiola, Jose; Sadovski, AlexeyThis work provides an analysis of sea surface temperature (SST) data in the Gulf of Mexico (GoM), and compares modeling methods to assess their performance through statistical simulation. The GoM is a region of global economic and environmental importance, including the notable Flower Garden Banks National Marine Sanctuary’s coral habitats. However, the area has largely not been focused on in terms of advanced SST modeling. The objective of this work is to provide insight into SST variability in the GoM by modeling time series data, concentrating on seasonal patterns and the overall linear warming trend. In the study, varying methods compared include a dynamic seasonal mean model, a dynamic sinusoidal regression model, a cyclic spline model, and a seasonal mean regression model with sandwich estimator. At the 95% nominal confidence level, methods ignoring the autocorrelation of error terms maintain empirical coverage between 60% and 80% to capture the linear yearly warming trends in the simulation. The recommended modeling approach, a dynamic sinusoidal regression model, provides such coverage of approximately 91.6%. It also offers a balance between accuracy, simplicity, and continuity, especially for frequently collected data. Analysis estimates the East Flower Garden Bank has an annual warming trend of approximately 0.028 ± 0.016°C. This comparative analysis of modeling techniques contributes to a better understanding of SST dynamics in this critical marine ecosystem.Item Icthyoplanktonic vertical distribution & ingress in the Aransas Pass inlet system(2023-12) Robson, Olivia Ann; Portnoy, David; Tolan, James; Withers, KimIn the Coastal Bend region of Texas desalination plants have been proposed as a solution to water usage problems. These plants take in brackish/marine water and dispose of brine, which in coastal inlets would create a plume of water with higher salinity and temperature. Desalination plants could impact estuarine dependent fishes whose larvae pass through the inlets on their way to nursery habitat. In this study I sample the Aransas Pass Inlet system, in the vicinity of one of the proposed desalination plans, during day and night and during both incoming and outgoing tides at three different depth strata, to provide data on larval assemblages in the channel. Results showed that larval were greatest in the deepest stratum and during nighttime hours. Key spawning months for several important families were also confirmed. Briny discharge may adversely affect larval development and survival depending on sensitivity to abrupt changes in salinity and temperature, which differs by species and developmental stage. Currently there are no specific regulations addressing desalination plant discharge, but this research suggests those regulations should limit the location and timing of discharge to mitigate potential negative impacts on local ichthyofauna.Item Benthic infaunal long term response to wastewater diffuser discharge in Lavaca Bay, Texas(2023-12) Sellers Jr., Crandon Dewylde; Montagna, Paul; Smith-Engle, Jennifer; Proffitt, EdThe Lavaca-Colorado Estuary (LCE) is one of seven major estuarine systems located on the Texas coast. As the second largest estuary in Texas, the LCE provides local and statewide residents with industrial, recreational, and agricultural benefits and historically known to be an abundant and diverse ecosystem for marine organisms. Previous studies have shown there has been long-term decline in benthic abundance, biomass, and diversity in the LCE since 1988. A more recent study found that in fact there was a long-term increase in benthic abundance, biomass, and diversity in the LCE since 1993. Multiple stressors, natural and anthropogenic in origin, are affecting biological community structure. Therefore, these stressors are transforming ecosystems. The purpose of this research is to continue the previous studies to determine if long-term diffuser discharge has any effect on benthic infauna communities in the sediment of Lavaca Bay. This thesis analyzes a 29-year long-term monitoring/time series dataset that was designed to evaluate the impact a discharge pipeline had on constituents of ecological and biological conditions in Lavaca Bay. The purpose of this study was to answer environmental questions about Lavaca Bay. The primary question is: Does the industrial discharge affect the ecological health of Lavaca Bay? If so, are the benthos being affected more near the diffuser site, or is the effect constant throughout the bay? The overall goal was to perform an analysis to determine which parts of the bay are being most affected and to reach conclusions about the overall bay health. Bay health can be indicated by a decline in benthic integrity (i.e., diversity), decreased survival rates of organisms exposed to sediments, and sediment chemical contaminant concentrations over threshold limits. The results revealed that industrial discharge does affect ecological health in localized areas near the outfall. Sediment characteristics closest to the outfall had higher combinations of silt and clay, possibly due to diffuser outflows disturbing the sediment and increasing turbidity. The water column had lower pH, temperature, and DO closer to the outfall. Survival predictions showed an increase over time suggesting that the diffuser does not negatively affect the survival rates of the benthic communities within the bay. However, benthic community diversity means were higher as distance increases away from the outfall. Therefore, even though the diffuser isn’t negatively affecting the overall benthic bay health, it has a negative local effect when compared to stations further away from the outfall area.Item A diversity baseline of benthic macrofauna along the northwestern insular slope of Cuba (Gulf of Mexico)(2023-12) Schiereck, Samantha; Montagna, Paul; Pollack, Jennifer; Schwing, PatrickThe Gulf of Mexico (GoM) is a unique ecosystem due to the physical characteristics influenced primarily by the Mississippi River in the North and the Loop Current, which originates in the south, resulting in a gradient of organic to carbonate sediment composition. The continental slope of the northern (US) and southwestern (Mexico) portions of the GoM are generally well studied; however, very little is known about the southeastern GoM along the slope of Cuba. To fill this knowledge gap, sediment cores were collected in 2017 at nine stations (974–1580 m depth) to gather baseline data and determine controls on the deep-sea benthic macrofauna community. Oceanographic data indicated a stratified water column typical of an oligotrophic ocean and no evidence of hypoxia. Sediment texture and composition indicated a west-east gradient likely determined by downslope transport of terrigenous material in the eastern part with a high proportion of carbonate in the west. Heavy metals (Cu, Hg, Pb, and Zn) at concentrations known to cause benthic effects were present in the east near the major city of Havana, with the macrofauna community showing characteristics indicative of environmental stress. Stations had a low overall average diversity (15 families/79 cm2) and abundance (7,980/ m2), with high variability among replicates within the stations. The diversity was 48% less, and the abundance was 14% less than in the northern GoM. The major factors influencing macrofauna communities in the continental slope off northwestern Cuba are most likely the lack of organically rich sediment, low sediment deposition rates, and the strong current.