Physical Sciences and Mathematics Commons^™

Population Ecology Of A Caribbean Epiphyte Trichocentrum Undulatum (Orchidaceae): Defining Habitat And The Effects Of Herbivory And Hurricanes At Its Peripheral And Core Range, Haydee Borrero

FIU Electronic Theses and Dissertations

Population ecology studies are central to species conservation. My dissertation focused on the Florida state-listed endangered orchid, Trichocentrum undulatum at its northern-most range in the Everglades National Park (ENP), Florida and multiple populations throughout its core range in Cuba. Through surveying populations of T. undulatum across this range from 2013-2021, I made a new reporting on the occurrence of a specialized insect herbivore, Melanagromyza miamensis in Cuba (Chapter 1). This flower-crippling herbivore was previously known only in the ENP. With this discovery I assess the intensity and impacts of this herbivore, as well as others on T. undulatum across the …

Evaluating Changes In Visible To Short-Wave Infrared Spectral Reflectance Of Arctic Mosses In Response To Experimental Drying To Find The Best Predictors Of Moisture Content, Steven L. Unger

FIU Electronic Theses and Dissertations

Mosses are a dominant understory component in the Arctic and because of sparse canopy cover, contribute to spectral signals used in remote sensing estimates of various ecologically important characteristics such as productivity, phenology, and vegetation mapping. However, little is known about their contributions to community level spectra or how moisture content influences those spectral signals. Unlike vascular plants, mosses cannot actively regulate moisture content and are highly susceptible to desiccation. Previous research has shown that moss reflectance is sensitive to tissue moisture content. Here, a lab-controlled drying experiment was conducted to identify the best spectral predictors of moisture content of …

Drivers Of Extracellular Polysaccharide Production By A Mat-Forming Diatom, Kaitlin A. Stansbury

FIU Electronic Theses and Dissertations

Microbial biofilms are held together by extracellular polymeric substances (EPS), which can be secreted by many organisms. EPS production can facilitate intercellular communication and inter-guild microbial mutualisms, intraspecific gamete exchange, nutrient sequestration, and desiccation resistance. Benthic microbial mats (periphyton) of the Florida Everglades and other karstic wetlands contain abundant EPS generated by mat-producing filamentous blue-green algae and many other species of mat-dwelling algae, cyanobacteria, and bacteria, including the most abundant Everglades diatom, Mastagloia calcarea. The benthic diatom genus Mastogloia is characterized by several morphological and physiological features that foster production of a ‘halo’ of EPS around the frustule, but the …

Quantifying How Coastal Flooding And Stormwater Runoff Drive Spatiotemporal Variability In Carbon And Nutrient Processing In Urban Aquatic Ecosystems, Matthew A. Smith

FIU Electronic Theses and Dissertations

Coastal river networks alter the transport and transformation of dissolved organic carbon (DOC) and dissolved organic matter (DOM), which can vary in concentration and composition across spatiotemporal scales. Given climate-induced shifts in rainfall and tidal variation in low-lying coastal regions, there is an increasing need to quantify effects of flooding on biogeochemical cycling. Specifically, urban flooding is becoming increasingly common due to biophysical alterations to hydrology from urbanization and climate change. Urban ecosystems have been characterized as having a distinct biogeochemistry compared to other systems, largely due to increased frequency and magnitude of riverine and coastal flooding. Consequently, the role …

Comparison Of Modern And Mid-Holocene Benthic Foraminifera To Assess Recent Environmental Change In Almirante Bay, Caribbean Panama, Maria N. Gudnitz

FIU Electronic Theses and Dissertations

This study used the diversity and distribution of benthic foraminiferal assemblages of Almirante Bay, Caribbean Panama, as environmental proxies to compare modern coral, seagrass and mangrove habitats to mid-Holocene coral reef facies on the island of Isla Colón, to investigate both natural and human-influenced changes.

The modern study associated species and assemblage characteristics with environmental conditions related to degraded water quality. Assemblages were fairly similar among neighboring habitats but differed in species proportions, while several stress-tolerant taxa might indicate eutrophic conditions. Diversity appeared to be regionally controlled by freshwater input irrespective of habitat type, was generally lower near the mainland …

Connections In The Underworld: A Morphological And Molecular Study Of Diversity And Connectivity Among Anchialine Shrimp., Robert Eugene Ditter

FIU Electronic Theses and Dissertations

This research investigates the distribution and population structure of crustaceans, endemic to anchialine systems in the tropical western Atlantic focusing on cave-dwelling shrimp from the family Barbouriidae. Taxonomic and molecular tools (genetic and genomic) are utilized to examine population dynamics and the presence of phenotypic hypervariation (PhyV) of the critically endangered species Barbouria cubensis (von Martens, 1872). The presence of PhyV and its geographic distribution is investigated among anchialine populations of B. cubensis from 34 sites on Abaco, Eleuthera, and San Salvador, Bahamas. Examination of 54 informative morphological characters revealed PhyV present in nearly 90% (n=463) of specimens with no …

Computational Analysis Of Large-Scale Trends And Dynamics In Eukaryotic Protein Family Evolution, Joseph Boehm Ahrens

FIU Electronic Theses and Dissertations

The myriad protein-coding genes found in present-day eukaryotes arose from a combination of speciation and gene duplication events, spanning more than one billion years of evolution. Notably, as these proteins evolved, the individual residues at each site in their amino acid sequences were replaced at markedly different rates. The relationship between protein structure, protein function, and site-specific rates of amino acid replacement is a topic of ongoing research. Additionally, there is much interest in the different evolutionary constraints imposed on sequences related by speciation (orthologs) versus sequences related by gene duplication (paralogs). A principal aim of this dissertation is to …

Changes In Soil Microbial Functioning In Coastal Wetlands Exposed To Environmental Stressors And Subsidies, Shelby M. Servais

FIU Electronic Theses and Dissertations

Environmental perturbations are ubiquitous features of ecosystems and shape ecological structure and function. Climate change will alter the intensity and frequency of disturbances and expose ecosystems to novel combinations of useful inputs (subsidies) and harmful inputs (stressors). Coastal wetlands are particularly vulnerable to changing environmental conditions and are increasingly exposed to effects of interacting subsidies and stressors. In particular, the Florida Coastal Everglades, which has experienced accelerated change due to a history of water management practices, is vulnerable to new disturbances associated with climate change. The low-lying Florida Everglades faces multiple disturbances from storm surge, nutrient enrichment, and sea-level rise …

Potential Effects Of Chemical Contamination On South Florida Bonefish Albula Vulpes, Christine P. Beck

FIU Electronic Theses and Dissertations

An ecological risk assessment was conducted on the risk to fish of chemical contaminants detected in the habitat of Albula vulpes in South Florida, to evaluate whether contaminants may be a driver of declines in the recreational bonefish fishery. All available contaminant detection data from Biscayne Bay, Florida Bay, and the Florida Keys were compared to federal and state guidelines for aquatic health to identify Contaminants of Potential Ecological Concern (COPECS). For these COPECs, species sensitivity distributions were constructed and compared with recent detections at the 90^th centile of exposure. Copper in Biscayne Bay was identified as the highest …

The Effect Of Disturbance And Freshwater Availability On Lower Florida Keys’ Coastal Forest Dynamics, Danielle E. Ogurcak

FIU Electronic Theses and Dissertations

Coastal forest retreat in the Florida Keys during the 20^th century has been attributed to a combination of sea level rise and hurricane storm surge impacts, but the interactions between these two disturbances leading to forest decline are not well understood. The goal of my research was to assess their effects over a period spanning more than two decades, and to examine the relationships between these press and pulse disturbances and freshwater availability in pine rockland, hardwood hammock, and supratidal scrub communities. Impacts and recovery from two storm surges, Hurricanes Georges (1998) and Wilma (2005), were assessed with satellite-derived …

Evidence Of Climate Variability And Tropical Cyclone Activity From Diatom Assemblage Dynamics In Coastal Southwest Florida, Emily R. Nodine

FIU Electronic Theses and Dissertations

Estuaries are dynamic on many spatial and temporal scales. Distinguishing effects of unpredictable events from cyclical patterns can be challenging but important to predict the influence of press and pulse drivers in the face of climate change. Diatom assemblages respond rapidly to changing environmental conditions and characterize change on multiple time scales. The goals of this research were to 1) characterize diatom assemblages in the Charlotte Harbor watershed, their relationships with water quality parameters, and how they change in response to climate; and 2) use assemblages in sediment cores to interpret past climate changes and tropical cyclone activity.

Diatom assemblages …

Habitat Use Of The Key Largo Woodrat (Neotoma Floridana Smalli), Lauren J. Barth

FIU Electronic Theses and Dissertations

Key Largo woodrats are an endangered subspecies with an extremely limited habitat. This study sought to understand woodrat habitat preferences in order to guide management. Woodrats build stick nests from natural and artificial materials, so nest distribution and nest occupancy were used as indicators of preference. Distribution was determined by nest surveys, and remote cameras were used to assess occupancy. Forest structure, human disturbance, nest, and animal presence metrics were also collected. More nests were found along abandoned roads than along forest transects and more artificial nests were occupied than natural nests. These findings indicate that woodrats prefer areas with …

Characterization Of Rhizobial Diversity And Relationship Of Rhizobial Partner And Legume Performance In Four South Florida Pine Rockland Soils, Vanessa Sánchez

FIU Electronic Theses and Dissertations

Pine rocklands are endangered ecosystems unique to south Florida, the Bahamas and Cuba. As a result of their karstic calcium carbonate­rich soil, these systems are limited in phosphorus and nitrogen, making symbiotic associations critical to plant growth. Four leguminous species (Cajanus cajan, Chamaecrista fasciculata, Tephrosia angustissima, and Abrus precatorious) were used to determine the relationship between rhizobial partners and plant performance, and the symbiosis related gene nifH was amplified to characterize the diversity of rhizobial symbionts. Plants were grown in soils from four different south Florida pine rocklands, and a salinity treatment was added to determine …

Spatio-Temporal Analysis Of Chilling Events In Mangrove Forests Of South Florida, Bina Thapa

FIU Electronic Theses and Dissertations

Chilling events are infrequent but important disturbances in subtropical Florida. When temperatures drop to near freezing, significant mortality often accrues in mangrove forests. Chilling events play a role in maintaining structural diversity in mangrove forests, and in limiting mangrove poleward distribution. I examined the spatio-temporal distribution of chilling events in mangrove forests of southern Biscayne Bay by using Landsat TM5 images since 1989. Damage was usually confined to dwarf mangrove forest, especially when chilling temperatures were moderate and short in duration. However, damage from extended and severe freezes such as in January 2010 impacted larger trees as well. Recovery is …

Controls On Ecosystem Carbon Dioxide Exchange In Short- And Long-Hydroperiod Florida Everglades Freshwater Marshes, Jessica L. Schedlbauer, Jay W. Munyon, Steven F. Oberbauer, Evelyn E. Gaiser, Gregory Starr

FCE LTER Journal Articles

Although freshwater wetlands are among the most productive ecosystems on Earth, little is known of carbon dioxide (CO₂) exchange in low latitude wetlands. The Everglades is an extensive, oligotrophic wetland in south Florida characterized by short- and long-hydroperiod marshes. Chamber-based CO₂ exchange measurements were made to compare the marshes and examine the roles of primary producers, seasonality, and environmental drivers in determining exchange rates. Low rates of CO₂ exchange were observed in both marshes with net ecosystem production reaching maxima of 3.77 and 4.28 μmol CO₂ m⁻² s⁻¹ in short- and long-hydroperiod marshes, …