Life Sciences Commons^™

Exploring The Consistency Of Flow Regimes Within And Among Ecoregions Of The Southeastern United States, Frank Paul Braun Iv

Electronic Theses and Dissertations

Human manipulation of river systems has long been a known contributor to the loss of freshwater biodiversity. By accounting for environmental causes of hydrologic variation among rivers, we can better understand how ecoregion mediates flow regimes and forecast species that may be at risk. Presumably, natural variation associated with ecoregion boundaries exerts strong influence on flow regimes, and may mediate relationships between other features (e.g., land use, dam operations) and hydrology. However, such between-ecoregion variation is poorly investigated, particularly at fine spatial and temporal scales. I characterized 10 hydrologic metrics, representing the five key dimensions of the flow regime (magnitude, …

An Assessment Of Functional Characteristics In Macroinvertebrates And Fishes In The Lower Ogeechee River, Molly A. Mckeon

Electronic Theses and Dissertations

The southeastern United States is a hotspot for aquatic biodiversity; yet this region is also considered vulnerable to climate and land–use changes. The Ogeechee River is an unimpeded blackwater river in Georgia that drains into the Atlantic Ocean and a unique ecosystem due to the preservation of its natural state; Historically, research conducted in the river establishes a baseline for long-term ecological studies. The aim of this study is to compare aquatic macroinvertebrate and fish community composition data collected in 2014 to 2017 to a recently collected dataset from 2023 and document temporal changes. Water quality monitoring was performed throughout …

What Are The Impacts Of Deer Browsing And Japanese Stiltgrass (Microstegium Vinenium) On Native Sapling Growth In A Residential Wetland In Southeastern Georgia?, Josie Richards

Honors College Theses

Wetlands promote biodiversity, act as climate stabilizers, and regulate water flow, yet are vulnerable to invaders. An invasive species can affect the biodiversity, abiotic conditions, and increase vulnerability of an ecosystem over time and deer browsing can actively affect new growth by removing the apical buds of young woody vegetation. Japanese stiltgrass (Microstegium vimineum), a wetland specific invader, has been shown to compete against native species for limited resources and actively crowd them out. Growth of native saplings can be further complicated by the presence of white tailed deer (Odocoileus virginianus), which browse woody vegetation and limit recruitment of trees. …

Middle Savannah River: An A/R/Tographic Ecopedagogical Ethnography Experimenting With Rhizomatic Perspectives, Lisa Augustine-Chizmar

Electronic Theses and Dissertations

This research is an experiment in perspective. Using the four commonplaces (Schwab, 1978), I practiced letting the Savannah River teach me what there is to know about the water, the land, the people, and the other entities that depend on ki through artistic, ethnographic, and ecopedagogical lenses. The ethnographic findings describe the social actors that depend on ki and give a voice to the River. The a/r/tographic findings display the River on a canvas map through two hundred years using paint, clay, photography, video, abstract acrylics, and fabric. Together, these methods contribute to a unique ecopedagogical journey. This word cloud …

Investigating Salinity Intrusion Effects On Sapelo Island, Georgia Using Benthic Macroinvertebrate Bioindicators, Raymond Paul Kidder Ii

Electronic Theses and Dissertations

Coastal wetlands are threatened by the compounding effects of sea level rise and historical land modification. Historically, much of Sapelo Island, Georgia was deforested and drained using a series of ditches and canals to create arable land fit for agriculture and to provide drainage to the inhabited parts of the island. Today, this network of artificial channels is believed to be facilitating the movement of saltwater from the nearby estuary into freshwater areas on the interior of the island. This study aimed to better understand the frequency and magnitude of salinity intrusion events along with their resulting impacts to the …

Developing Best Practices For The Propagation Of Spartina Alterniflora For Use In Salt Marsh Restortaion, Justin Hinson

Electronic Theses and Dissertations

Coastal salt marshes are valuable ecosystems under threat from climate change and sea level rise. Living shorelines offer a promising solution, often incorporating the foundational salt marsh species Spartina alterniflora due to its ability to tolerate natural stressors and maintain sediment stability. However, research suggests that seed-based propagation protocols should be developed on a local scale due to the genetic heterogeneity within and between S. alterniflora populations. Here, we attempt to contribute to the development of one such protocol for coastal Georgia S. alterniflora.

In Fall 2021, seeds were collected bi-monthly from four marshes of varying ocean proximity and …

Spatial Drivers Of Freshwater Fish Biodiversity, Community Structure, And Diet Composition Across Georgia, Usa, Patrick Lewis

Electronic Theses and Dissertations

The geographic complexity of the Southeastern United States, in particular Georgia, is evident in the diversity of stream habitats present throughout that host unique stream fish communities but is threatened by anthropogenic activity. This spatial complexity can be captured through the ecoregion framework, which delineates areas of distinct habitat. However, this differing habitat character between ecoregions leads to different environmental pressures that may promote species heterogeneity between communities, may create intraspecific niche diversity in widely distributed species, and may complicate the transferability of widely accepted theoretical models of fish ecology between them. I analyzed a long-term fish community dataset, examining …

Impacts Of Algal Morphology And Water Flow On Macroalgal Microplastic Capture, Cheyenne M. Adams

Honors College Theses

Microplastic pollution is a major area of concern in marine environments, especially as microplastics enter the food web. This study used pipe cleaners and two lichen species as algal mimics, and Chaetomorpha sp. and Chondrus crispus as model algal species to test the effects of morphology and biomass on microbead and foam capture. This study also utilized two different water flow methods: vortices and waves. Results suggest that water flow, as well as biomass and morphology, play a role in microplastic capture in macroalgae. For all mimics and algal species, except Cladonia lichens, turfs with increased biomass and length showed …

Influence Of Plant Density On Rainfall Interception By Spartina Alterniflora, Hannah K. Longaberger

Honors College Theses

Abstract

Spartina alterniflora is an abundant plant in eastern US and Gulf coast salt marshes; it is important in maintaining a diverse ecosystem. Salt marshes are impacted by rainstorms, which may affect erosion events. This project examined the partitioning of rainfall on single plants of various sizes and on central plants within different canopy densities of S. alterniflora. By calculating the rain stemflow (SF), throughfall (TF), and water adhered to the stem in S. alterniflora, we gained insight to rainfall partitioning with different plant features. My research found no statistically significant relationship between different plant features and SF, TF, …

Effects Of Water Quality On Oyster Health On Georgia Coast, Laurel Henderson

Honors College Theses

ABSTRACT

Oysters are an economically and ecologically important shellfish species found along most coastlines. Along the Georgia coastline, oysters form extensive reefs, and are economically important as a food source. In addition, oysters perform a vital role in maintaining water quality due to their high filtration capacity in coastal waters. Oyster reefs form solid, 3-D substrate that prevent coastline erosion and provide structure for numerous other coastal species to grow, including many commercially and recreationally important species. Water quality factors, such as temperature and salinity, can influence oyster density, condition, and growth, and ultimately affect the services the reefs provide …

The Potential Role Of Phenotypic Plasticity In The Ability Of Hydrocotyle Bonariensis To Occupy Two Different Habitats, Harold Ralph Parsons Iii

Honors College Theses

Phenotypic plasticity is the ability of an organism to change morphology and/or physiology in response to changes in the environment. Hydrocotyle bonariensis is a coastal perennial herb found in both coastal sand dunes and inland coastal plain habitats in Georgia. The purpose of this study was to determine if there were differences in leaf morphology for populations of H. bonariensis in coastal sand dune and inland coastal plain habitats. Leaf morphology and microenvironmental variables were compared between H. bonariensis populations at Tybee Island (TI), GA, representing the coastal sand dune habitat, and Georgia Southern University Armstrong Campus (GSU) in Savannah, …

Macroinvertebrate Responses To Hydrological Variation In Experimental Wetlands., Sergio A. Sabat-Bonilla

Electronic Theses and Dissertations

Predicted increases in the frequency of intense storms and periods of severe drought due to climate change represent a threat to wetland macroinvertebrate communities through alterations to the hydrological regime. I used experimental ponds to assess the effects of water permanence (i.e., duration of flooding) on the communities of aquatic macroinvertebrates. I predicted that permanent ponds would harbor higher diversity of longer-lived taxa whereas temporary ones will favor colonization by quick turnover, short-lived taxa and support lower consumer diversity. Results show differences in macroinvertebrate communities between permanent and temporary ponds can be mostly explained by hydrology and the amount of …

Evaluating St. Catherines Island's Shoreline, Vegetation Line, And The Locations Of Loggerhead Sea Turtle Nests, Sydney O. Davis

Electronic Theses and Dissertations

St. Catherines Island is a highly dynamic barrier island on the Georgia coast that is also federally listed critical nesting habitat for loggerhead sea turtles. Understanding how St. Catherines’ shoreline and vegetation is changing over time is geographically important as a potential template for other barrier islands. Measuring sea turtle nest locations will provide insight into their natural patterns and how they adjust those locations on a changing barrier island. Analyzing Moving Boundaries Using R (AMBUR) is implemented in this research to assess the movement of the vegetation and shorelines from 2005-2017 using the End Point Rate (EPR) and Linear …

Assessing Habitat Suitability Of Ribbed Mussels (Geukensia Demissa) In Georgia Salt Marshes By Examining Predicted Mussel Densities And Mussel Population Parameters, William K. Annis Jr

Electronic Theses and Dissertations

Geukensia demissa (ribbed mussel) is an ecology important bivalve that has the potential to contribute to salt marsh restoration. Understanding the factors that contribute to the distribution of mussels can help inform managers on choosing locations to optimize the survivorship of mussels in restoration projects. This study sought to model mussel densities across the coast of Georgia and to compare predicted mussel densities with mussel population parameters as means to gauge habitat suitability. Mussel densities were collected through field surveys across a range of salt marshes along the coast of Georgia and were compared with spatial data such as distance …

Steady Heartbeat: Field And Laboratory Studies Indicate Unexpected Resilience To High Temperatures For The Ribbed Mussel Geukensia Demissa, Ashlyn N. Smith Ms.

Honors College Theses

Salt marshes are important ecosystems found along the coast of Georgia. Salt marshes are hosts to diverse organisms that interact with each other to promote many ecosystem services, such as storm buffering and flooding, and absorption of excess nutrients. Among these diverse organisms is the ribbed mussel, Geukensia demissa. Mussels are a foundation species in this intertidal landscape, and without them the whole salt marsh would be negatively affected. The purpose of this investigation was to explore the thermal stress response of G. demissa to rising temperatures. Mussels were collected from three locations that were landlocked, close to a …

Surfacant Contamination Alters Freshwater Phytoplankton Community Composition, William H. Hodge

Electronic Theses and Dissertations

Pollution from cleaning and personal care products enter freshwater systems and have the potential to alter phytoplankton abundance and diversity. Alkyl polyglucoside (APG), a widely used foaming agent in detergents, decreases phytoplankton abundance, but whether sensitivity to APG is affected by taxonomic identity and/or the presence of competitors is unclear. Establishing taxon-specific responses to APG is important, because taxa differ in nutritional quality and palatability for zooplankton grazers.

Chapter one describes comparisons between how individual phytoplankton communities respond to the same range of APG concentrations to test hypotheses that: 1) chemical concentration determines how individual taxa respond to APG; 2) …

Scaling And Ecological Relationships In The Visual Ecology Of Sharks, Brianna Hall

Electronic Theses and Dissertations

Adaptations of visual systems, such as acuity, sensitivity, and eye size can be used to infer the relative importance of vision to an organism. The high metabolic cost of visual system development and maintenance suggests that large relative eye size (as it relates to body length) may have a significant ecological or evolutionary role. Elasmobranchs are morphologically diverse and inhabit a wide range of marine and freshwater niches. As energetic and ecological demands shift over time, several species occupy different predatory niches across their lifetime, yielding a large array of visual habitats. Additionally, eye size changes with body length allometrically, …

A Multi-Scale Investigation Of Habitat Selectivity In Coastal Plain Stream Fishes, Hayley A. Robinson

Honors College Theses

Studying the habitat use of Coastal Plain fishes enables us to develop a deeper understanding of how fishes thrive in this highly variable environment. Based on previous research by Dr. Roberts and his students, Coastal Plain fishes seem to sort into two groups: (1) species selecting stream reaches that continue to flow throughout the summer (i.e., fluvial species [F]) and (2) species occurring in streams that may stop flowing in late summer (i.e., nonfluvial species [NF]). For this study, I took a detailed look at eight of these species, spanning the F-NF gradient, and asked which environmental variables (e.g., water …

Identification Of Bird-Associated Nonpoint Sources Of Microbial Contamination In Sediments, Savannah D. Mullins

Honors College Theses

Fecal indicator bacteria (FIB), such as Enterococci, are commonly used to monitor the microbial contamination of recreational beach waters based on standards set by the United States Environmental Protection Agency. Sediment and sand may also harbor FIB and reintroduce these bacteria to the water column. Enterococci may be originated from various non-point sources such as humans and wildlife. Recent literature has shown that avian feces also harbor high concentrations of Enterococci. The purpose of this study is identify the relationship between Enterococci and avian-associated markers in sediments. Sediment samples were collected monthly from four sites at Kings Ferry Beach in …

Wetland Biogeochemical Responses To Predicted Climate Change Scenarios, Angela R. Shaffer

Electronic Theses and Dissertations

Wetlands are one of the world's largest known carbon sinks while comprising only a small amount of the Earth's surface. However, the amount of carbon sequestered by wetlands is shrinking as droughts and human disturbance increases. Carbon in wetlands is stored through the contrast of decomposition and sedimentation of organic matter and absorption of CO₂ from the atmosphere by soil microbes. Understanding how changing hydrological regimes and increased wildfires will affect wetland soil and microbial processes is important in the face of predicted climate change for future wetland conservation practices. Specifically, I seek to understand the response of southeastern …

Effects Of Climate Variability: A Long-Term Perspective On Leaf Litter Processing In The Ogeechee River, Jose A. Sanchez

Electronic Theses and Dissertations

The Intergovernmental Panel for Climate Change (IPCC) predicts a rise in temperatures and changes to precipitation patterns for the 21^st century. These changes are expected to lead to a higher frequency of extreme events such as drought and floods which lead to the alteration of the hydrology, communities, and processes of freshwater ecosystems. Leaf litter decomposition in stream ecosystems is an important component of the energy and nutrient cycle representing a food source for aquatic organisms. This has made it a tool for assessing long term responses to disturbance due to changes in the assemblage of macroinvertebrates that …

Quantifying The Morphological And Physiological Effects Of Drought, Grass Invasion, And Fire On Longleaf, Loblolly, And Slash Pine, Laura Young

Electronic Theses and Dissertations

Climate change is altering ecosystems on a global scale, creating novel ecological scenarios with which plant species must cope. Factors such as altered precipitation and fire regimes and non-native plant invasion may negatively affect native plant species, while interactions between these stressors could magnify their impacts. The complexity of multiple stressors and the effects they have on native pine seedlings are difficult to predict without evaluating their combinations in field experiments. In a multi-year study, I investigated the effects of drought and plant invasion on three southeastern pine species under pre and post-fire conditions. We planted longleaf (Pinus palustris …

Inferring Food Web Structure To Identify Seasonal And Longitudinal Patterns In Ogeechee River Invertebrate Communities, Julien Marc Buchbinder

Electronic Theses and Dissertations

Understanding how the structure and function of aquatic communities vary across space and time is essential for proper management of freshwater ecosystems. Current management relies on rapid biomonitoring using metrics of community structure, but metrics that incorporate ecosystem processes and functions are only just beginning to see use in assessment and management. Food webs inferred from known species interactions have been proposed as a method of incorporating function into bioassessment without expending extra effort or sacrificing the cost-effectiveness of current monitoring schemes. To apply food webs in biomonitoring, it is first necessary to understand how communities and food webs vary …

Successional Processes In The Benthic Invertebrate Communities At Gray’S Reef National Marine Sanctuary, Alexis A. Bivens

Honors College Theses

While the process of community development has been studied in terrestrial habitats since the turn of the 20th century, similar information is not as readily available in marine systems. Understanding patterns of community development is essential to predicting recovery potential and to designing effective marine protected areas. In the South Atlantic Bight, invertebrate communities on hard substrata can differ significantly from one rocky outcrop to another, but the factors driving these differences are not well understood. I documented the initial development of the benthic invertebrate community at Gray’s Reef National Marine Sanctuary (GRNMS) to address the prediction that this system …

Predictors Of Fish Assemblage Structure And Dynamics In Atlantic Coastal Plain Streams, Rebecca Scott

Electronic Theses and Dissertations

Effective management of freshwater fishes requires a mechanistic understanding of the drivers of assemblage composition; in other words, what determines who is where and when. Stream fish assemblages are potentially influenced by environmental factors that act on multiple spatiotemporal scales, but the relative influence of these drivers may vary between geophysically distinct regions. This study sought to determine the patterns and drivers of fish taxonomic and functional assemblage composition in the coastal plain, a region possessing unique hydrologies, faunas, and physiochemical conditions. I addressed this goal using two complementary chapters, both of which utilized environmental and biotic data collected from …

Comparison Of Three Benthic Macroinvertebrate Passive Sampling Devices For Non-Wadeable Streams, Kelsey A. Laymon

Electronic Theses and Dissertations

Rivers and streams provide essential ecosystem services to the degree that the monitoring and maintenance of these systems becomes imperative. Biomonitoring provides managers and policymakers with the tools to make informed decisions, and macroinvertebrates are often the object of biomonitoring because they are ubiquitous in most systems and are known to be good indicators of water quality. However, methods for sampling macroinvertebrates in non-wadeable streams (i.e., large rivers) have not been standardized across states and regions and an established method for macroinvertebrate biomonitoring in large rivers of Georgia is not currently available. My study compared macroinvertebrates collected with three types …

Quantification And Characterization Of Net Precipitation Bacterial Flux From A Subtropical Epiphyte-Laden Oak Forest, Preston Pound

Electronic Theses and Dissertations

Transport pathways of microbes between ecosystem spheres (atmosphere, phyllosphere, and pedosphere) represent major fluxes in nutrient cycles and have the potential to significantly affect microbially-mediated biogeochemical processes. We quantified a previously unexamined microbial flux from the phyllosphere to the pedosphere during rainfall via throughfall (rainfall dripping from the canopy and through gaps) and stemflow (rainwater funneled down the stem). Bacterial concentrations were quantified using flow cytometry and validated with quantitative Polymerase Chain Reaction (qPCR) assays for samples from a Quercus virginiana (oak)- forest with heavy epiphyte cover (Tillandsia usneoides, Spanish moss) in coastal Georgia (Southeastern USA). Bacteria concentrations …

Silver Nanoparticle Fate And Accumulation In The Aquatic Food Web Of Stream Microcosms, Stefan J. Petersen

Electronic Theses and Dissertations

Silver nanoparticles (AgNPs) are used in 25% of all nano-enabled products and applied for anti-microbial properties. Silver nanoparticles are discharged into aquatic environments through wastewater discharge, runoff, and chemical spills. Once in aquatic environments silver nanoparticles have the potential to harm aquatic organisms. While the fate of silver nanoparticles in lentic systems has been investigated, limited information is available for the fate of silver nanoparticles in flowing environments. The purpose of this study was to compare the fate of AgNPs following a one-time pulsed application simulating a chemical spill, or small repetitive applications simulating effluent discharge, in artificial stream communities …

An Industrial Chemical Used In Coal-Washing Influences Plankton Communities In Freshwater Microcosms, Danielle Turner

Honors College Theses

In 2014, 4-methylcyclohexane methanol (MCHM), an industrial chemical used to wash coal, contaminated drinking water in 300,000 homes in West Virginia, USA and raised concerns about toxicity to humans and freshwater ecosystems. The Centers for Disease Control and Prevention determined that a concentration of 1 ppm was safe for human exposure. Despite the concern for human consumption, it is important to determine if MCHM has negative effects on aquatic organisms in contaminated water, particularly plankton communities that comprise the base of freshwater food webs. I exposed freshwater plankton communities in microcosms to 0, 0.5, 1 or 3 ppm MCHM under …

Assemblage Structure, Production, And Food Web Dynamics Of Macroinvertebrates In Tropical Island Headwater Streams, Keysa G. Rosas-Rodriguez

Electronic Theses and Dissertations

Variation in long-term temperature and precipitation patterns will likely influence the decomposition and export of benthic organic matter and influence aquatic macroinvertebrate consumer communities. Tropical systems are relatively understudied; therefore basal information is urgently needed. As part of an ongoing long-term study, we monitored macroinvertebrates in two shrimp-dominated and fishless headwater streams within the Luquillo Experimental Forest in Puerto Rico from 2009-2010. We combined growth rates with yearly biomass data to calculate secondary production and examined gut contents to develop quantitative food webs. Macroinvertebrate assemblages were dominated by a few insect taxa, with similar biotic composition across streams and habitats, …