Ecology and Evolutionary Biology Commons^™

Microplastic Composition And Exposure Pathways In Freshwater Systems: A Multi-Matrix Comparison Between Streams And Retention Ponds In Hamilton County, In, Mya Whaley

All-Inclusive List of Electronic Theses and Dissertations

Since the early 1900s, the use of plastics has increased exponentially. The breakdown of plastic materials has exposed all ecosystems to microplastics (small particles of plastic < 5 mm), which are now ubiquitous in natural settings. Microplastics have a relatively large surface area, and many chemicals adsorb to these small particles, impacting their fate and transport of pollution. While microplastics have been found in virtually every setting on Earth, research is necessary to understand their impact on freshwater ecosystems and biogeochemical cycles. The focus of this research was to investigate microplastic compositions in crayfish, sediments, and water samples collected in streams and retention ponds. We analyzed trends in microplastic counts across different land-cover classes, waterbody types, and species, and compared concentrations among matrices to improve our understanding of microplastic exposure pathways in freshwater ecosystems. As a secondary objective, lead and arsenic concentrations were analyzed from sediment samples to investigate metal burdens and compare them to microplastic concentrations. Our findings revealed that, in general, urban streams had the highest microplastic concentrations within land cover categories, and retention ponds had higher microplastic counts than streams. Crayfish, such as F. rusticus had higher microplastic concentrations than F. virilis and F. propinquus, although these results may be influenced by study design. The most common microplastic type was fibers, and most common color was transparent. There was no significant correlation between microplastic and metal concentrations in sediments. We found crayfish to be adequate bioindicators of microplastic pollution, because they were less impacted by environmental variability than sediment and water samples. This research presents the first evidence of microplastics in our study species, F. propinquus, F. rusticus, and F. virlis. This work presents new evidence of microplastic accumulation in crayfish, sediments, and water from freshwater systems in the Midwestern United States. Microplastics were found in every sample type—crayfish, water, and sediment—across urban, rural, and forested landscapes, highlighting their pervasive distribution. The findings provide foundational data for assessing emerging ecological and human-health risks and emphasize the importance of sustained monitoring and research on MP contamination in freshwater environments.

Quantifying Macrophyte Ecosystem Services And Improving Environmental Nonprofit Messaging, Peyton R. Hughey

All Theses

Environmental nonprofits are essential to the management and restoration of our natural spaces. They are also tasked with engaging the public via outreach, education, and advocacy. As natural spaces are degraded, the ability of environmental nonprofits to deliver on their missions will become increasingly important. This study aimed to improve two approaches to environmental nonprofits’ missions: ecological restoration and social media communication.

Environmental nonprofits operate with limited resources, and ecological restoration can be an exhaustive task; therefore, we explore functional restoration as a tool. In this study, we focus on the use of functional, trait-based restoration to restore ecological function …

Forest Overstory Mortality & Recruitment Patterns Eight Years Following Wildfire In The Southern Appalachians, Ruth Cumberland

All Theses

In this study, we investigated patterns of forest overstory mortality and recruitment eight years after wildfire in a large wildfire site the Southern Appalachians, a topic that has not been thoroughly investigated to date. With evidence that pre-fire drought promotes post-fire mortality through impaired physiological function and increased fuel consumption, unknown patterns following wildfire are important to study under shifting climate and land-use conditions. In Chapter 1, three areas of interest were investigated: (a) functional group mortality response to wildfire effects, (b) temporal differences in early (1-3 years) and late (5-8 years) periods of delayed forest overstory mortality patterns following …

Polydactyl Precursors: Insights Into Early Tetrapod Locomotion From Polydactyl American Alligators, Trevor P. Brewington

All Theses

Several of the earliest tetrapod lineages exhibited polydactyl limbs, with seven or eight digits per limb rather than the typical five or fewer seen in extant lineages. How these digit configurations might have been used during terrestrial locomotion is unclear, given the lack of living models in which their performance can be studied and limited evidence from fossil trackways. However, polydactyly occasionally appears in natural populations of American alligators (Alligator mississippiensis), animals with body plans that broadly resemble those of early tetrapods. To test how polydactyl limbs similar to those of early tetrapods might have functioned on land, …

Characterizing The Molecular Response Of Embryonic Zebra Finch To Acute Sound Playback, Saidat O. Adeniran-Obey Miss

All Theses

Auditory stimuli are important cues that influence developmental plasticity in animals and are important for development and adaptation to an ever-changing environment. In the zebra finch (Taeniopygia guttata), there is evidence of adaptive developmental reprogramming in response to a prenatal ‘heat call’. Embryos exposed to this heat call exhibit changes in growth rate post-hatch, increased heat resistance, and enhanced reproductive success at maturity. However, it has long been assumed that embryonic zebra finches cannot respond to sound due to the immaturity of their auditory system. These findings raise the critical question of whether late-stage zebra finch embryos can, …

A Series Of Investigations On The L. Cornutus Host System And Bivesiculid Sp. Cercariae, Briana K. Zaffiro

All HCAS Student Capstones, Theses, and Dissertations

Rising global temperatures are likely modulating parasite-host interactions, yet the direction and magnitude of these changes remain uncertain. Rarely are these interactions viewed from both a host and parasite perspective. Using both CT_max, or Critical Thermal Maximum, and Clark-type polarographic oxygen microelectrodes, the physiological metabolic effects are investigated. CT_max is examined in Common Shiners, Luxilis cornutus, and is shown to be modulated by parasitism: uninfected fish had the highest CT_max average of 37.0°C, whereas heavily infected fish had decreased CT_max averaging 35°C. Prior to the parasite metabolic investigation, a suitable medium was determined, as …

Degradation And Metabolic Analysis Of Synthesized Quorum-Sensing Signals By The Model Eukaryote Chlamydomonas Reinhardtii, Adam Josef Bach

Theses and Dissertations

Bacterial organisms can “talk” with one another on a colony-wide scale using a communication system known as quorum-sensing (QS) via chemical signals. These signals are produced at a basal rate throughout the life of the bacteria and are classified as autoinducers, which diffuse across the cell membrane. Once the critical concentration is reached, they begin to diffuse back into the cell and initiate a phenotypic change. As these signals exist outside the membrane of their producer, they are also accessible to other organisms. It has already been noted that some plant species uptake these compounds through their roots and break …

Shape Variation In The Mandible Of The Borophagine Canids And Implications For Predatory Behavior, Benjamin Neavear

Theses, Dissertations and Culminating Projects

The borophagines are an extinct lineage of canids that inhabited North America for more than 20 million years. This group included genera such as Aelurodon, Borophagus, and Epicyon. Borophagines are commonly referred to as “bone-crushing dogs” because their skull morphology converged with that of extant hyenas, predators capable of consuming bone. The purpose of this study was to determine whether convergence was present in the mandible, an anatomical structure strongly correlated with feeding behavior, particularly in the genera Aelurodon and Borophagus. It was hypothesized that most borophagine taxa possessed mandibular shapes similar to those of hyenas. Numerous mandibular characters were …

Bats And Bacteria: Infection Dynamics At The Human-Wildlife Interface, Isabella Katherine Deanglis

Graduate Theses and Dissertations

As the second most diverse mammalian order, bats host an array of pathogens, some of which are known to infect humans. Synanthropic bats share spaces with humans, resulting in bat-borne pathogen exposure. While most bat-borne disease research has focused on viral pathogens, bats host numerous bacterial pathogens with zoonotic potential. By integrating a global meta-analysis with field studies in Sub-Saharan Africa, I characterize the structural attributes that facilitate shared interfaces, the bacterial pathogens present in synanthropic bats of rural Kenya, and the physiological and environmental dynamics influencing odds of infection in these synanthropic bats. Finally, I evaluate the clinical relevance …

Twenty-Four-Hour Intermittent Fasting Extends Lifespan At The Expense Of Fecundity In Daphnia, Meridith L. Smith

Undergraduate Honors Theses

Dietary restriction (DR) is a well-established intervention for extending lifespan, yet the specific efficacy of intermittent fasting (IF) and its associated trade-offs remain under-explored in many Daphnia magna. This study investigated the effects of three IF intervals—2h, 24h, and 48h—on the longevity and fecundity of two clones of Daphnia. We hypothesized that longer fasting intervals would significantly extend lifespan at the cost of reproductive output, consistent with the disposable soma theory of resource allocation.
Our results demonstrate that 24h IF significantly increased longevity relative to ad libitum controls, even outperforming caloric restriction (CR) by reducing late-life mortality. In …

Discovering The Genetics Underlying Speciation Traits In Heuchera (Coral Bells), Tajinder Singh

Honors Theses

Hybridization is a key evolutionary mechanism for generating biological diversity, ultimately shaping diversification and adaptation of plant lineages in natural and agroecosystems.  Our understanding of the frequency, distribution, and significance of hybridization is rapidly increasing, but the external driving forces that dictate why certain species hybridize, and others do not remain obscure. The physical traits that shape gene flow and trait sharing among species are likely to be among the key factors that directly control hybridization. Gene flow in most plants is mediated by pollinating insects and thus by pollination syndromes, which are suites of floral traits that have evolved …

Sex Or Survival: Does Wounding Elicit A Somatic Reproductive Tradeoff In Narnia Femorata Males?, Lillian E. Burbulis

Departmental Honors & Graduate Capstone Projects

Animals must partition resources into different life history traits resulting in tradeoffs because resources are finite. A tradeoff is the allocation of resources to one trait over another. Theory states that energy is allocated in a hierarchical fashion. For example, somatic maintenance should be a higher priority than reproduction, resulting in more resources being allocated to somatic maintenance compared to reproductive traits. The metabolic investment hypothesis states that energy must follow a hierarchical order prioritizing somatic maintenance over reproduction. Another hypothesis for energy allocation is the terminal investment hypothesis. This hypothesis states that energy will be allocated to reproduction over …

The Spatial Distribution Of Coccidia In Arkansas Freshwater Snails, Julia R. Pye, Taylor M. Fiedor, Jason M. Post, Kyle D. Gustafson

Create@State

Coccidia are obligate, intracellular parasites that infect the digestive tracts of many animals and cause coccidosis, which can result in vomiting, diarrhea, and in severe cases, death. At broader scales, the disease contributes to substantial economic losses in agriculture. Our study examined the distribution of Pfeifferinella ellipsoides, a coccidian parasite in freshwater snails. Based on previous research, we hypothesized that (1) there will be statistically significant spatial clustering in northern Arkansas and (2) the parasite will be found exclusively in two snail genera, Physa and Planorbella. We sampled 17 snail species and surveyed feces for oocysts from 1,920 snails and …

How Pollinator Populations Can Impact Chronic Disease Risk, Kylee Cubbison

Honors Projects

This project investigates how pollinator populations can impact chronic disease risk. Pollinator populations are declining, which can have serious implications for human health. Declining pollinator populations can limit healthy food production and affordability. Poor nutrition is a major risk factor for most chronic diseases. Less healthy food available for people to consume can negatively impact diets and increase the risk of developing chronic diseases. This project aims to address a potential gap in research existing on this specific topic regarding pollinator populations and human chronic disease risk. A brochure targeted towards educating the general public on this topic was created …

Aggression And Fish Welfare: Challenges And Opportunities, Christine M. Soper, Peter D. Dijkstra

Animal Sentience

Oldfield & Bonano’s (2024) [O&B] target article discusses the wellbeing and sociality of bony fishes. Many fish species, such as cichlids, are not only social but territorial. Aggression is normal, but territorial aggression in a captive environment can have a negative impact on welfare. Aggression-related injuries and deaths are prevalent in pet stores as well as research settings. We discuss the need to develop effective methods to minimize the negative consequences of aggression.

Impact Of Pvc Microplastics On The Growth Of Raphanus Sativus, Olivia Fawkes, Alissia D. Fulton, Darlene Panvini

SPARK Symposium Presentations

Microplastics have emerged as a growing concern due to their increasing prevalence in terrestrial ecosystems. Understanding how microplastics affect plant growth is crucial for the agricultural industry, as crop productivity and soil quality have a direct impact on food security and farm sustainability. This study examined the impact of polyvinyl chloride (PVC) microplastics on the germination and growth rate of Raphanus sativus. Seeds were grown for six weeks in a controlled growth chamber in petri plates and soil pots containing varying concentrations of PVC microplastics (0, 25, 50, 75, 100 mg/L), including untreated PVC and PVC artificially weathered through …

New Ways To Address The Plastic Problem, Andrew J. Hanna

The Penguin Review

Since 1950, the world has produced some 9.2 billion metric tonnes of plastic.1 Other sources place the total closer to ten billion metric tonnes Furthermore, nearly 500 million tonnes of new plastic are manufactured each year– a figure that's projected to increase to 1.2 billion tonnes by 2060.2 The environmental effects of all this plastic production and pollution are disturbing. Because most plastics are synthetic–meaning they contain "no molecules found in nature"– they can't decompose. Instead, they just break down into smaller and smaller pieces, becoming microplastics (less than five millimeters (5 million nanometers) across) and then nanoplastics (less than …

Skin Pattern As A Potential Monitoring Tool For Frog Populations, Lídize Sagarnaga Rivera, Virginie Rolland Dr., Lorin Neuman-Lee Dr.

Create@State

Skin pattern as a potential monitoring tool for frog populations

Population monitoring, which requires identifying individuals, is crucial for species conservation. Common techniques involve marking, which can harm animals and alter their behaviors. Natural markings are an alternative not yet explored for amphibians. Yet, the traditional method with elastomers (fluorescent implants) is invasive and not completely reliable—the tag may become lost or hard to see. The American green tree frog (Dryophytes cinereus) possesses naturally occurring and distinct golden dots on their dorsal side.  Therefore, we aim to assess whether patterns of golden dots on the skin of green …

Variation In Infection Prevalence Of Splendidofilaria Pectoralis Across Alaskan Grouse Populations, Anahi Garcia Valdez, Diego Martinez

Create@State

In recent years, rapid climate change has altered species distributions worldwide and influenced parasite transmission dynamics in wildlife systems. Parasite infections play an important role in shaping patterns of disease distribution across species and populations. Understanding variation in infection prevalence across geographic regions and host demographic groups is essential for interpreting these patterns. Splendidofilaria pectoralis is a filarial nematode that infects the connective tissues of grouse (Aves: Tetraonini) in Alaska and has been moving northward as the climate warms. However, relatively little is known about the variation in prevalence of the nematode across geography and demography. This project examines variation …

Evaluating The Impact Of Residential Landscape Audits Using 5-Second Water Use Data, Mahmud Aveek, Camilo J. Bastidas Pacheco, David E. Rosenberg, Jeffery S. Horsburgh, Kelly Kopp, Belize A. Lane

Civil and Environmental Engineering Student Research

We used 5-s water use data to evaluate the effectiveness of residential landscape water audits in summer 2022. Fifty-nine households in two northern Utah cities were monitored for 2–5 weeks before and 3–10 weeks after an audit. We found that the distribution of weekly irrigation volumes postaudit was statistically less than the distribution preaudit (significant at the 1.9E10-5 level). Collectively, the participants reduced their landscape irrigation water use by approximately 379,000 L per week (100,300 gal per week; 0.3 acre-feet per week). We also analyzed changes in irrigation event volume, duration, frequency, and the number of days between events at …