Ecology and Evolutionary Biology Commons^™

Dam It All: A Multi-Scalar Investigation Into The Ecological Role And Function Of Beaver Dams, Kenneth Larsen

Dissertations, Master's Theses and Master's Reports

The central theme of this dissertation is ecological scaling, which examines how small, localized features, such as beaver ponds, contribute to large-scale watershed processes and how different modeling approaches at various scales reveal distinct insights. Through a combination of probabilistic modeling and high-resolution empirical research, this work demonstrates that small ponded systems, particularly those created by beavers (Castor canadensis), serve as critical biogeochemical control points, whose contributions to sediment and nutrient dynamics have been historically underestimated.

In Chapter 1, I contextualize this research within the broader fields of freshwater ecology, watershed modeling, and ecological restoration. I introduce the …

Sugar Maple (Acer Saccharum Marsh.) Tree-Ring Growth And Carbon Stable Isotope Responses To Nitrogen And Climate, Libbie Ring

Dissertations, Master's Theses and Master's Reports

This dendrochronological and stable carbon isotope study used tree rings from sugar maple (Acer Saccharum Marsh.) collected at long-term nitrogen (N) amended sites throughout Michigan to understand N amendment and deposition, climate, and growth relationships. Climate responses varied by site, however, we found importance in grouping sites by “productivity” which is related to inherent N and soil nutrients. Our results did not detect an overall effect of N amendments on growth during the treatment period. However, data shows N amendments benefiting larger diameter trees, while smaller diameter trees responded more positively without amendments, especially on more productive sites. Results …

Binoculars To Bytes: Development And Field Validation Of An Ai-Driven System For Avian Monitoring, Christian J. Dupree

Graduate Student Theses, Dissertations, & Professional Papers

Autonomous camera-trap arrays coupled with artificial-intelligence (AI) vision can lift bird monitoring beyond the spatial, temporal, and labor limits of traditional field surveys. We present Binoculars to Bytes (B2B), an open-source pipeline that turns 180–360° time-lapse imagery into analysis-ready avian data. At Freezout Lake Wildlife Management Area (Montana, USA) the system ran four-hour morning deployments during spring and fall migrations (2023–2024). A YOLO-NAS detector, incrementally refined with a “Specialized Localized Iterative Model” workflow, quadrupled local accuracy and, after confidence-based species-binning, cut false-positive rates in half. Daily AI species lists were benchmarked against contemporaneous eBird citizen-science checklists and recovered ≥ …

Spatial And Temporal Patterns Of Nutrient Limitation In A Western Montana River, Matthew T. Nichols

Graduate Student Theses, Dissertations, & Professional Papers

Enhanced loading of nitrogen (N) and phosphorus (P) is pervasive in rivers around the world. As a consequence of nutrient-rich conditions, many well-lit rivers experience severe algal blooms, which threaten water quality and aquatic habitats. Nutrient enrichment in the upper Clark Fork River, located in western Montana, has increased the productivity of benthic algae, Cladophora glomerata, which routinely forms extensive blooms during summer growing seasons (July – September). Addressing eutrophication in rivers begins with identifying the nutrients that contribute toward algal productivity. I deployed nutrient diffusing substrates (NDS), collected bi-weekly surface water samples, and conducted algal surveys at four …

The Impacts Of Permafrost Thaw Slumps On Arctic Stream Ecology, Maria Dolan

Theses and Dissertations (Comprehensive)

Climate change is intensifying permafrost thaw across terrain of the circumpolar Arctic. Increased temperatures and rainfall at northern latitudes have resulted in the expansion of thermokarst features such as retrogressive thaw slumps, which make previously frozen debris available for transport into nearby river systems. In the Peel Plateau, Northwest Territories, the mobilization of these materials exposes rivers to a large quantity of sediment and solutes that may act as a chronic, press disturbance, potentially altering stream food webs. Here, I examine if: 1) thaw slumps have driven changes to the physical and biological properties of slump impacted streams since an …

Quantifying Ecological Processes Predicting Barren-Ground Caribou (Ɂetthën; Rangifer Tarandus Groenlandicus) Occurrence Across A Heterogenous Northern Indigenous Protected And Conserved Area., Eric Jolin

Theses and Dissertations (Comprehensive)

Northern ecosystems are experiencing a period of rapid and unprecedented change, with implications for species distributions, mammal community dynamics, and habitat associations. Understanding the ecological processes that shape species distributions is crucial for developing effective conservation strategies that can adapt to such change. This study examines drivers of barren-ground caribou occurrence, a species of cultural and ecological significance, across Thaıdene Nëné Indigenous Protected Area, an ecologically intact landscape of high habitat heterogeneity straddling the treeline of the Northwest Territories. I use spatial and temporal variation in caribou detections generated by camera traps to test the relative importance of apparent competition, …

Thermokarst Can Stimulate Tall Shrub Productivity And Plant-Soil Feedbacks In The Low-Arctic Tundra, Claire O'Brien

Theses and Dissertations (Comprehensive)

Warming temperatures are exacerbating permafrost thaw disturbances in the Arctic. Permafrost thaw disturbances are facilitating tall, deciduous shrub expansion. However, potential productivity differences between shrubs that colonize disturbed areas and those in undisturbed tundra remain understudied. More productive shrubs optimize for fast growth over leaf longevity, meaning they may produce more abundant and higher quality litter which could accelerate decomposition rates and lead to faster nutrient cycling. Faster nutrient cycling could create a positive feedback loop between shrubs and soil, maintaining greater ecosystem productivity. I measured in situ soil characteristics and physiological and structural shrub functional traits for green alder …

Activity, Movement, And Reproductive Patterns Of The Northern Giant Musk Turtle (Staurotypus Triporcatus) In Belize, Larissa Sage Saarel

Graduate Theses/Dissertations

The Northern Giant Musk Turtle (Staurotypus triporcatus), a near-threatened species native to southern Mexico, Guatemala, Belize, and western Honduras, faces multiple environmental challenges, yet its activity patterns, movement patterns, and reproductive biology remain poorly understood. This thesis investigates both seasonal activity and reproductive cycles of female S. triporcatus in Belize. To assess diel and seasonal activity, I tracked 12 female turtles and collected data using activity loggers. I also collected movement data through radio-telemetry and acoustic tracking methods. Results indicated that the species is primarily nocturnal, with increased activity during the wet season, particularly during flooding events. Turtles …

Seagrass Buried In The Dark: Reduced Light And Moderate Levels Of Burial Have Additive And Lethal Impacts On Posidonia Sinuosa, Nicole Said, Chanelle Webster, Kathryn Mcmahon, Natasha Dunham, Charlie Phelps, Ankje Frouws, Jack Robinson, Kieryn L. Kilminster, Simone Strydom

Reports accepted as research outputs

Executive Summary: Quantifying interactive effects among multiple stressors is important for understanding cumulative impacts on seagrasses, which is imperative for informing the appropriate management of marine ecosystems. To date, many thresholds used to understand seagrass response to dredging are based on singular stressors, such as light reduction or burial, but these pressures often occur simultaneously. Understanding the impacts of multiple stressors, which may act additively, synergistically or antagonistically, could require adjustment of existing single pressure derived thresholds. Furthermore, the recovery time of seagrasses to individual and multiple pressures has been identified as a major gap in literature. Improving our understanding …

Investigating The Mechanisms Of Freeze Tolerance In Lemna Minor, Tamara Bouchard

Honors Theses and Capstones

Freezing presents a significant abiotic stress to aquatic plants, yet little is known about the mechanisms by which species like Lemna minor (duckweed) survive subzero temperatures in nature. This study investigates whether L. minor employs freeze-avoidance or freeze-tolerance strategies and explores the potential role of its microbiome in enhancing cold resilience. Using both field-collected fronds from naturally frozen ponds and controlled freezing experiments in the lab, I assessed survival through viability staining and post-thaw survival. Results showed that L. minor can survive natural ice encasement and that prior cold acclimation significantly improves tissue survival under induced freezing. Trypan blue staining …

Seasonal Occupancy Of The Thermal Plume Of A Spring Tributary To The South Fork Roanoke River, Virginia., Steven L. Powers, Michael M. Calvert, Charlotte M. Spaulding

Southeastern Fishes Council Proceedings

Detection of temperate stream fishes varies widely across seasons as streams teeming with life in summer often appear empty during winter sampling efforts. While much literature documents the disproportionate use of the thermal plumes of spring tributaries by cold water fishes during summer, few studies have investigated occupancy of those habitats by warm water fishes in winter. We conducted quantitative snorkeling observations within the near uniform temperatures (10-14^oC) of the thermal plume of a spring tributary to the South Fork Roanoke River across seasons and compared number of fishes observed and species richness to control observations made just …

Co2 In Flowing Freshwaters: Macro Scale Database Compilation, Addressing Ph Bias In Co2 Estimates, And Quantifying Cross-Scale Interactions, Timothy R. Toavs

LSU Doctoral Dissertations

This dissertation focuses on carbon dioxide (CO₂) dynamics in flowing freshwaters, contributing to the growing body of knowledge about inland water carbon cycles. The research is structured into three main chapters, each progressing towards the objective of utilizing variability in flowing freshwaters to further understand carbon dynamics, anthropogenic land cover impacts, and potential impacts from a changing climate. Chapter one compiles a 30-year dataset of pCO₂ measurements from flowing freshwater systems across the contiguous United States. This dataset, referred to as CDFLOW, includes over 750,000 pCO₂ estimates from more than 35,000 locations. It serves …

Native Freshwater Mussel Communities In The Lower Grand River, Michigan: Assessing Tributary Confluence Effects And Updating Survey Information, Grayson L. Kosak

Masters Theses

Freshwater mussels (Unionidae) are ecosystem engineers and keystone species vital to stream ecosystems yet represent the most imperiled group of freshwater fauna. Conservation of unionids necessitates further understanding how assemblages interact with watershed features. This study investigates mussel occupancy, distribution, and assemblage structure upstream and downstream of tributary confluences in the lower Grand River, Michigan, alongside updated surveys of the unionid community with comparisons to previous assessments conducted by Michigan Natural Features Inventory (MNFI) in 2002–2003. Unionid density, richness, and diversity were greater upstream of confluences. No significant distance-gradient effects were observed. Assemblage structure differed between upstream and downstream reaches …

Social Learning And Cultural Enrichment For Fish Welfare, Chiawen Chiang, Becca Franks

Animal Sentience

This commentary examines how understanding animal culture—shared behaviors and knowledge transmitted through social learning—plays a role in advancing welfare practices for captive fishes. Despite extensive evidence of fishes' complex sociocultural capacities, their psycho-social needs remain underestimated and unmet in zoos and aquaria. We explore what considering fish culture might mean for welfare practices: diverse social learning opportunities, cultural development, and thoughtful group management. More knowledge about wild fishes' lives will help bridge the gap between their full, complex lives and current captive welfare practices.

Invasion Stress Mitigates Climate Stress In A Brackish Marsh Amphipod, Lorna E. Haworth, Sarah Nancollas, Susie N. Landa, Anne E. Todgham, Richelle L. Tanner

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

1. Organisms in coastal brackish ecosystems face not only highly variable environmental conditions, but the intensity and stochasticity of these environmental conditions are anticipated to increase due to climate change. While environmental changes are often presented unilaterally as stressors, there are some anthropogenic environmental transformations, such as the introduction of habitat forming plant species, that may mitigate physiological stress imposed by warming. In Suisun Marsh in the California Delta, native plant canopies allow light and heat to penetrate to the understory yet the canopies of the introduced Phragmites australis reed block out sunlight and heat for organisms living below.
2. We set …

Bat Activity Across Urban Forest Plantings In Lexington, Kentucky, Grayson Marie Collier

Online Theses and Dissertations

Urbanization has led to major forest loss and negatively impacts ecosystem services. Urban reforestation efforts, such as Reforest the Bluegrass (RTB) in the Lexington-Fayette metropolitan area of Kentucky, have been implemented to address these negative effects, and to create habitat for forest-dependent wildlife such as bats. My research focused on assessing differences in bat activity across a 20-year chronosequence of RTB sites. Acoustic detectors were deployed across 10 different-aged plantings at 60 randomly-defined detector locations. Each planting was surveyed across 8 sampling periods from May – August 2023. Each recording session spanned ca. 7 consecutive nights, yielding a total of …

Cyperus Blepharoleptos Maxent Ecological Niche Models, Samuel A. Schmid, Maxwell G. Gebhart, Gray Turnage

GRI Publications

Invasive species are one of the foremost threats to global biodiversity and predicting where they can inhabit is of primary concern for researchers and resource managers. Ecological niche models (ENMs) are a useful tool for addressing this problem. This study focuses on Cyperus blepharoleptos (Cuban bulrush), an aquatic sedge that is invasive in the southeastern United States. To model the ecological niche of C. blepharoleptos, 1,137 records were compiled from North and South America and partitioned into training and testing data. Five BioClim variables (BIO1, BIO7, BIO12, BIO14, and BIO15) were selected as environmental variables for modeling. Using Maxent, 12 …

Spatial Ecology Of Large Bodied Ichthyofauna In The Red River Of The North Basin, William Marshall Stuart

School of Natural Resources: Dissertations, Theses, and Student Research

Understanding spatial patterns and processes is essential for designing research studies, implementing management actions, and planning restoration efforts. The Red River of the North basin spans a broad geographic area where jurisdictional oversight is divided among several entities (Manitoba, CAN; North Dakota, USA; Minnesota, USA; South Dakota, USA), creating a mosaic of regulatory and functional process zones. Understanding the spatial ecology of freshwater fishes in this disjointed landscape is essential to address diverse life history requirements and the movement constraints imposed by anthropogenic structures. Long-term acoustic telemetry revealed that large bodied ichthyofauna employ a diverse range of movement strategies (i.e., …

Spatiotemporal Patterns In Orbicella Faveolata Wound Regeneration As An Indicator Of Colony Health, Alexander G. Wheeler

All HCAS Student Capstones, Theses, and Dissertations

Anthropogenic (e.g. damage from anchors, scuba divers, tissue sampling) and natural disturbances (e.g. predation, storm damage) can result in wounding of live tissue on coral colonies. Wounding has been shown to detract from a common resource pool, increasing disease susceptibility and impairing coral growth and reproductive activity. Regeneration not only varies between species, but also between conspecifics in the same location. A colony’s capacity to regenerate tissue can be an indicator of a colony’s condition and resilience. Understanding the physiological and environmental factors that affect tissue regeneration alongside the ultimate impact of sampling (disease and predation correlations) are needed for …

The Influence Of Wind Energy Development On Occupancy Of Medium And Large-Sized Mammals In South Texas, Elwynn Sherman

Theses and Dissertations

Conservation paradigms have shifted from single to multi-species approaches for assessing and conserving mammalian populations and the habitats that they occupy. The effect of wind turbine development is an important anthropogenic change to study due to the increasing demand for wind energy in Texas. In this study, I gathered remote camera trap data on medium and large-sized mammal populations in south Texas Tamaulipan thornscrub habitat. The objectives were to determine species presence, the effect of habitat characteristics and anthropogenic disturbances on species occupancy, and the effect of temperature on species detection. The results showed that distance from wind turbines did …

Comparing Metabolism And Hypoxia Tolerance Of Native And Non-Native Florida Freshwater Fishes In Climate Change Scenarios, Benjamin A. Share

All HCAS Student Capstones, Theses, and Dissertations

As climate change brings rising water temperatures and lower dissolved oxygen (DO) concentrations to freshwater bodies, it has become increasingly important to understand how this will affect ecosystems with established non-native or invasive species. Fishes of the family Cichlidae are the most pervasive non-native fishes in the Everglades and may increase their range further north under a changing climate. To better understand potential invasibility and competition with native fishes, the metabolism and hypoxia tolerance of non-native Blue Tilapia Oreochromis aureus was compared to native Bluegill Lepomis macrochirus when acclimated across a range of seasonal and projected temperatures. Intermittent-flow respirometry was …

Investigating The Acute Physiological Effects Of Effluent Crystal Violet On The Freshwater Bioindicator Daphnia Pulex, Hoang K. Ho

2024 Fall Honors Capstone Projects - Archive

This study examines the effects of acute exposure to crystal violet (CV) on the freshwater zooplankton Daphnia pulex in response to growing concerns over synthetic dyes from industrial runoff in aquatic ecosystems. The primary objective is to assess CV's impact on D. pulex's heart rate, mobility, morphology, and lethality via a series of acute exposure tests. 48-h acute toxicity (0-2000 μg/L), 48-h immobilization (0-180 μg/L), and 9-h heart rate (0-2,000 μg/L) tests were conducted using third-generation daphnids, followed by stereomicroscopic examination and statistical analysis. Results showed increasing mortality and decreasing mobility and heart rate with increasing CV concentration; the …

Phytoplankton Responses To Changing Irradiance And Carbon Fertilization, Alison Siersma

Graduate Theses and Dissertations (2019 - present)

Phytoplankton play a crucial role in marine ecosystems due to their innate ability to fix carbon. As atmospheric CO2 levels continue to rise from fossil fuel combustion, the resulting increase in dissolved CO2 and the concurrent decrease in ocean pH are likely to impact the phytoplankton community. The response of phytoplankton to elevated CO2 can vary significantly among species and environmental conditions (e.g. light, temperature, nutrient availability). To address these variations, an experiment was conducted using a controlled photobioreactor system, maintaining high and low light, constant temperature, nutrient levels, and two pCO2 concentrations. This study focused on two regionally relevant …

Evaluating The Success Of A Relocated Mussel Community In The Lower Sulphur River, Texas, Rachel M. Leicher

Biology Theses

Conservation efforts to preserve freshwater mussel communities have become more common as these animals become increasingly threatened by their changing habitats. As humans continue to shape and change the world around them, aquatic species living in modified and disturbed water systems can be negatively impacted leading to decline of the ecosystem. During disturbance events involving a stream, river, or pond, the relocation of affected mussel beds is becoming more widespread. Although there are few of these studies, many of those that have been conducted are seen as successful in relocating and conserving their mussel communities. This study focuses on detection …

Investigating Nekton Response To Changing Salinities In The Mississippi Sound: An Experimental And Statistical Approach, Adam Murray

Master's Theses

The Mississippi Sound provides nursery habitats for many coastal species and is recognized for its commercial fisheries. Previous freshening events linked to the Bonnet Carré Spillway, a Mississippi River flood diversion structure, proved catastrophic for oyster populations in the Mississippi Sound, but effects on mobile fish and shellfish species are not well-defined. The planned Mid-Breton Sediment Diversion (MBSD), an initiative to combat wetland loss, is also forecasted to lower salinities in the region, increasing the need to better understand responses of commercially and ecologically important species to freshening events. The objective of this study was to characterize effects of salinity …

Bioindicators Of Mercury In Riverine Systems, Kathryn Mudica

All-Inclusive List of Electronic Theses and Dissertations

This study focuses on the bioaccumulation and biomagnification of mercury in freshwater food webs, with emphasis on bioindicators, such as macroinvertebrates, crayfish, and river otters. Despite regulatory efforts and advancements in monitoring, significant gaps remain in understanding mercury dynamics in freshwater systems—especially regarding its transport, methylation, and bioavailability across different ecosystems. To address these knowledge gaps, this study adopts a biocentric approach, emphasizing the role of living organisms in their environment. By utilizing macroinvertebrates, crayfish, and river otters as bioindicators, we aim to assess mercury bioavailability and distribution. These organisms provide varying temporal and spatial scales of mercury accumulation, offering …

Time Series Decomposition Of Land Surface Temperature For Long-Term Trend Forecasting And Impact On Nesting Sea Turtle Habitats In The Arabian Gulf, Sachi Perera, Rommel H. Maneja, Mohamed Allali, Cyril Rakovski, Erik Linstead, Daniele Struppa, Ali Qasem, Hesham El-Askary

Mathematics, Physics, and Computer Science Faculty Articles and Research

Improving land surface temperature (LST) modeling is vital for mitigating climate change effects on various ecosystems and marine habitats such as important sea turtle habitats. Over the past decade, extreme temperatures have likely significantly affected nesting sea turtle habitats in the Arabian Gulf, with predominantly female hatchlings creating an imbalance in the sex ratio. Such shifts have profound implications for these habitats’ long-term survival and conservation management. This study leverages statistical machine learning models to measure ongoing temporal variations in LST. We break down the LST time series into trend, seasonal, and noise components using classical decomposition methods like X11, …

Frogs On A Plain: Spatial Ecology Of Crawfish Frogs In Arkansas’ Remnant Prairies, Elliot T. Lassiter

Graduate Theses and Dissertations

The prairie peninsula was an expansive and important habitat that covered much of midwestern North America, from Canada to Arkansas, USA. But the prairie peninsula has shrunk by as much as 99% since 1830, and therefore, land acquisition and public/private partnerships are critical for the preservation of prairies and their associated species. In Arkansas, one species that benefits from protected prairies is the Crawfish Frog (Lithobates areolatus), which is currently declining precipitously throughout its range. Adult Crawfish Frogs spend most of their lives in terrestrial refugia (crayfish burrows), making them highly vulnerable to habitat loss and fragmentation, thereby …

Influence Of Hydrologic And Anthropogenic Disturbance On Stream Populations And Communities, Sarah Frances Sorensen

Graduate Theses and Dissertations

Disturbances occur when an external force modifies a habitat, destroying living space, removing food resources, or altering or destroying habitat structure. In lotic systems, a primary source of disturbance is hydrologic disturbance, including drought and flood. Hydrologic disturbances lead to increased mortality rates and dispersal out of disturbed habitats, causing population sizes to decrease and changes to community structures. More research is needed on how disturbances impact stream species and communities, as disturbances are predicted to become more intense with climate change. This dissertation aims to understand how disturbance influences streams at both the population and community level, through a …

Understanding Mechanisms For Coastal Marsh Sustainability In A Changing Climate, Ashley R. Booth

LSU Doctoral Dissertations

In the Chenier Plain of Louisiana and Texas, coastal marshes are subject to high rates of relative sea level rise (RSLR), restricted sedimentation, and declining elevation attributed to subsidence and decades of intensive management. These marshes were created via mineral sedimentation but now largely accrete via organic matter accumulation. This organic matter accumulation (OMA) – or the balance between plant productivity and decomposition – is essential for maintaining elevation and thus long-term sustainability. However, management for elevation is complicated by a poor understanding of how abiotic factors like flooding and salinity impact processes driving OMA and elevation. To better understand …