Life Sciences Commons^™

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 …

Reconstructing Cyclical Browning In A Subtropical Lake From Diatoms, Meredith Emery

FIU Electronic Theses and Dissertations

Lakes are browning globally from increased inputs of colored dissolved organic carbon (cDOC) driven by climate and land-use change. Browning changes lake ecosystems, especially through reductions in water transparency. I used long-term limnological and plankton records and upper surface sediment diatom assemblages to infer a ~1600-year history of browning from diatom assemblages in a 166 cm core from a subtropical, oligotrophic lake known to experience cyclical browning related to climate oscillations. Diatom assemblages were strongly regulated by cDOC-driven transparency fluctuations in a 14-year plankton dataset (modern model, R² = 0.62) and in the upper 35 cm of sediments corresponding …

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 …

Long-Term And Seasonal Drivers Of Phytoplankton Assembly In A Subtropical Monomictic Lake, Kristy Lee Sullivan

FIU Electronic Theses and Dissertations

Seasonal phytoplankton dynamics in lakes are highly sensitive physicochemical changes in the water column. As climate-driven frequency and variability of precipitation increases, lakes may experience increased inputs of allochthonous organic matter and nutrients through pulsed rain events. The resultant effects of lake physicochemistry on phytoplankton seasonal succession and assemblage are poorly understood. In the current study, the phytoplankton assemblage of a subtropical monomictic lake was examined in the context of natural interannual oscillations in allochthonous dissolved organic carbon and nutrient inputs resulting in prolonged clear-water and dark-water phases over a 14-year period. Differences in water clarity and nutrient concentrations among …

Beyond Predation: How Do Consumers Mediate Bottom-Up Processes In Ecosystems?, Bradley Austin Strickland

FIU Electronic Theses and Dissertations

By eating and scaring prey, predators can exert strong effects on communities and ecosystems. In addition, some animals may physically alter habitats and may recycle nutrients through digestion, both of which affect resources available to producers. Bottom-up effects initiated by large predators have not been well-studied and could prove to be important for understanding food webs and how ecosystems function. American alligators (Alligator mississippiensis) are abundant mobile predators that are capable of engineering aquatic habitats by moving organic material across ecosystem boundaries and creating and maintaining alligator ponds. In this dissertation, I documented the scale of ecological impacts …

Understanding, Quantifying, And Reducing Bias In Fisheries-Independent Visual Surveys, James Kilfoil

FIU Electronic Theses and Dissertations

Understanding spatiotemporal changes in populations is vital for conservation managers to assess current recovery efforts, determine future conservation priorities, and forms the basis to explore complex ecological questions. In fisheries, these data have traditionally been collected using fisheries-independent surveys that rely on extractive sampling practices (e.g., longlines, gillnets, trawls). However, with the growing availability of low-cost, high-definition cameras, researchers are increasingly using visual surveys as a non-invasive alternative. Camera surveys have a number of advantages including their archivable data, and offer insights into species habitat use and behavior. However, the use of cameras has a number of inherent biases. Understanding, …

Taking Apart The Time Machine: Investigating Space-For-Time Substitution Modeling In The Florida Everglades, Theresa Kelly Brown

FIU Electronic Theses and Dissertations

Space-for-Time substitution modeling has been used with increasing frequency to identify functional relationships between environmental drivers and ecological responses. I investigated the use of space-for-time substitution as a null model and beta diversity as a validity test for this null model in the Greater Everglades aquatic metacommunity. I began by conducting a literature review and analysis to investigate the suitability of the space-for-time substitution method as a null model. I then analyzed beta diversity of the Greater Everglades aquatic metacommunity through a sums-of-squares approach. Finally, I tested for correlation between the beta diversity analysis and the space-for-time models. Results indicate …

Mechanisms For The Persistence Of The Coral Holobiont In The Warming Oceans Of The Anthropocene, Daniel G. Merselis

FIU Electronic Theses and Dissertations

Coral Reefs are rapidly deteriorating in response to an onslaught of human-mediated stressors. Just one stressor alone, climate change, may extirpate coral reef ecosystems within a human lifetime, threatening societal and ecological catastrophe. Reef-derived ecosystem services are crucial for sustenance, coastal protection, and economic prosperity in over 100 countries. Near-term human decisions will determine whether reef-corals, the ecosystems they engineer, the 25% of marine biodiversity they support, and the human communities that depend upon them can be protected. My dissertation aims to characterize the potential for corals' adaptive mechanisms to facilitate their continued survival- information which will only represent hope …

Cavity Nest Webs As A Template For Studying Non-Trophic Interactions In Invasion Ecology, Joshua M. Diamond

FIU Electronic Theses and Dissertations

Invasive exotic animals are considered destructive forces in cities for preying on and competing with native species. I examined an aspect of competition from a different perspective, focusing on the role of Miami’s rich exotic bird assemblage in its cavity nest web, where a supply of woodpecker-created cavity nests limited by urbanization is the focal point of competition. We located 967 nest trees with 1,864 cavities and determined that woodpeckers successfully nested in this tropical urban region by exploiting standing dead palms (snags). Native upland forests were the most important cover type for woodpeckers but planted landscapes like parks and …

Survival At The Summits: Amphibian Responses To Thermal Extremes, Disease, And Rapid Climate Change In The High Tropical Andes, Kelsey E. Reider

FIU Electronic Theses and Dissertations

Understanding biological responses to climate change is a primary concern in conservation biology. Of the ecosystems being rapidly impacted by climate change, those in the high-elevation tropics are among the most poorly studied. The tropical Andean biosphere includes record elevations above 5000 meters, where extreme environmental conditions challenge many organisms. In the Cordillera Vilcanota of southern Peru, frogs including Pleurodema marmoratum and Telmatobius marmoratus have expanded their ranges to 5244 – 5400 m into habitats created by glacial recession, making them among the highest recorded amphibians on Earth. To understand how hydrologic alterations from loss of glacial meltwater and climatic …

Habitat Use Of Three Abundant Predatory Fish Species In The Freshwater Marshes Of The Florida Everglades, Alex T. Ontkos

FIU Electronic Theses and Dissertations

The Florida Everglades presents a model setting for studying animal-habitat relationships in a dynamic landscape that is heavily influenced by seasonal hydrology and water management. I used dynamic, high-resolution habitat classification maps and radio-telemetry to examine habitat preference of Largemouth Bass, Bowfin, and Florida Gar before and after a field-scale manipulation was established to address uncertainties with Everglades restoration and water management practices. Results indicate preference for the canal habitat by all three species, which represents only a small portion of the submerged landscape even in the driest conditions. Bowfin and Florida Gar were more likely to be relocated within …

Spatial And Temporal Patterns Of Arctic Nearshore Fish Community And Food Web Structures, Mark B. Barton

FIU Electronic Theses and Dissertations

Climate change and increasing anthropogenic activities are causing rapid changes to environmental and ecological processes in the Arctic Ocean. To better understand these changes, scientists have increased research efforts in these regions, but to date the number of studies on Arctic nearshore habitats are lacking. My dissertation responds to the paucity of information and investigates patterns in Arctic nearshore fish communities and food webs to gain insight to how these ecosystems may shift as these changes continue. I used multivariate statistical analysis to examine patterns in community structure and composition to determine that Arctic nearshore fish communities are largely driven …

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 …

Linking Husbandry And Behavior To Enhance Amphibian Reintroduction Success, Luke Jack Linhoff

FIU Electronic Theses and Dissertations

Wildlife in captivity has a long history of benefiting global conservation goals. Captive animals can raise awareness and appreciation for the conservation of endangered species. Additionally, captive animals can be used as source populations to reintroduce animals back to the wild or to supplement existing wild populations. The rapid increase in amphibian species threatened with imminent extinction has necessitated the creation of dozens of captive-breeding programs. The focus of this dissertation has integrated topics across the spectrum of animals in captivity and the wild, and the results provide useful recommendations for conservation action. First, I describe how market pressures over …

Impact Of Herbivory, Structural Complexity, And Sediment On Caribbean Coral Reefs, Alain Duran

FIU Electronic Theses and Dissertations

The resilience of coral reefs depends, among others, upon local physical and biological characteristics. This dissertation focused on how herbivory, structural complexity, and sedimentation can impact the structure, function, and, ultimately, resilience of Caribbean coral reefs. We filled an important knowledge gap related to trophic niche and ecological roles of surgeonfishes (A. coeruleus and A. tractus), two of the most important herbivorous fishes in the Caribbean. We showed that both species feed primarily on turf algae preventing further progression of algal succession while A. tractus may also help reduce macroalgal abundance by targeting common macroalgal species such as …

Phenomenological And Molecular Basis Of The Cnidarian Immune System, Tanya Brown

FIU Electronic Theses and Dissertations

Coral reefs are one of the most diverse ecosystems on the planet due partially to the habitat structure provided by corals. Corals are long lived organisms that can live for hundreds of years and as a result growth of many species is very slow. As a result of this, recovery of corals from disease outbreaks is very slow and difficult and therefore the ecosystem is deteriorating rapidly. Due to this increase in disease and its detrimental effect on coral reefs, it has become imperative to study how corals respond to disease outbreaks. The response of the coral to pathogens is …

Experimental Analysis Of The Effects Of Hydroscape Structure On Fishes In A Dynamic Wetland, Michael R. Bush

FIU Electronic Theses and Dissertations

Hydroscape structure can play a critical role in animal behavior, abundance, and community structure dynamics. Hydroscape configuration can be dynamic and can change quickly in ephemeral systems. However, ephemeral freshwater wetlands are among the most impacted systems in the world and restoration efforts often rely on incomplete information when establishing management objectives. Further understanding how alterations in hydroscape structure in dynamic systems affect animals is critical for conservation and management success.

To determine impacts that changing hydroscape conditions can have on consumers in freshwater wetlands, I examined the effects of a large-scale physical model on fish behavior, abundance, and community …

Examining Movement And Habitat Selection Of Everglades Fishes In Response To Seasonal Water Levels, Gregory J. Hill

FIU Electronic Theses and Dissertations

Fish distribution patterns and seasonal habitat use play a key role in the food web dynamics of aquatic ecosystems, including the Florida Everglades. In this study I examined the fine scale habitat shifts and movements of spotted sunfish, Lepomis punctatus across varying seasons and hydrologic conditions using in-situ field enclosures and Passive Integrated Transponder (PIT) systems. Data on fish use of three dominant Everglades marsh habitats and activity level were recorded continuously from January to August, 2015. Fish were more active and had the highest use of higher elevation habitats when water levels rose during an experimental reversal in mid-April. …

An Ecological Study Of The Anurans In Tea Plantations In A Biodiversity Hotspot, Lilly M. Eluvathingal

FIU Electronic Theses and Dissertations

Increasing human population size is increasing the demand for resources like timber, oil, tea, coffee, and other crops. Plantation crops mimic some aspects of native habitats, and there are studies that report the presence of some native anuran biodiversity in plantations. I focused on tea plantations in the Western Ghats-Sri Lanka Biodiversity Hotspot and studied the diversity and health of anurans in different habitats found within a tea cultivation area, near Munnar region in the Western Ghats, India. The landscape includes tea bushes, native evergreen shola forest patches, and eucalyptus forest stands. I reviewed 40 studies comparing amphibian species richness …

Investigating Sub-Tropical Community Resistance And Resilience To Climate Disturbance, Ross E. Boucek

FIU Electronic Theses and Dissertations

Changes in global climate will likely increase climate variability. In turn, changes in climate variability have begun to alter the frequency, intensity, and timing of climate disturbances. Continued changes in the climate disturbance regime experienced by natural systems will undoubtedly affect ecological processes at every hierarchical scale. Thus, in order to predict the dynamics of ecological systems in the future, we must develop a more mechanistic understanding of how and in what ways climate disturbance affects natural systems. In South Florida, two climate disturbances recently affected the region, a severe cold spell in 2010, and a drought in 2011. Importantly, …

Pesticides And Pollination Of Imperiled Plants Of The Lower Florida Keys, Brittany M. Harris

FIU Electronic Theses and Dissertations

Degraded pollinator habitat may have far-reaching consequences for recovery of imperiled flowering plant populations. Studies indicate that broad-spectrum insecticides used in mosquito abatement are detrimental to non-target invertebrates, including pollinators. A decline in efficient pollinators can reduce plant fitness by decreasing reproductive output and constraining genetic diversity, a challenge for rare plants.

In 2015, I monitored flower visitation and fruit set of three imperiled plant species throughout protected areas on three islands in The Lower Florida Keys. These islands consist of conservation land fragmented by intermittently dispersed residential neighborhoods that seasonally spray insecticides for mosquito control. Flowers open at treatment …

Responses Of Four Non-Tidal Forest Communities Of The Florida Everglades To Hurricane Impact Over 21 Years, Jeremy L. May

FIU Electronic Theses and Dissertations

The regular occurrence of hurricane-associated winds has been an important factor in shaping the structure and composition of the forest ecosystems of the Florida Everglades. Forest communities in the Everglades are adapted to hurricane disturbances, but increased frequency and/or intensity of hurricanes may lead to decline or even collapse of these communities. The overall objective of this project is to understand the patterns, pace, and mechanisms of the recovery process to Hurricane Andrew damage in four Everglade forest communities: pinelands, hardwood hammocks, bayhead tree islands, and cypress domes. This study combines long- and short-term field measurements and experimental garden studies …

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 …

The Effects Of Climate Warming On Plant-Herbivore Interactions, Nathan Lemoine

FIU Electronic Theses and Dissertations

Rising temperatures associated with climate change will alter the fundamental physiological processes of most ectothermic species. Drastic changes in catabolic and anabolic reaction rates exert strong effects on growth, reproduction, and consumption rates that cascade up through all levels of the biological hierarchy. This dissertation determined how climate warming might alter the important relationship between plants and insect herbivores, as mediated through changes in herbivore physiology. Consumption and fitness increased with temperature for almost all consumers. However, all consumers also exhibited a critical temperature, beyond which consumption declined rapidly through metabolism continued to increase. This mismatch in metabolic demands and …

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 …

Stable Isotope Biogeochemistry Of South Florida Coastal Marine Ecosystems, Sarah Elise Strand

FIU Electronic Theses and Dissertations

Southeast Florida’s continual urban expansion will potentially increase anthropogenic pollution in adjacent coastal marine systems. Furthermore, increased nutrient loads could have detrimental effects on the already threatened Florida Reef Tract. The present study uses a stable isotopic approach to determine the sources and the impact of nutrients on the Florida Reef Tract. δ¹³C and δ¹⁵N analysis of macroalgae, sponges, and sediment were analyzed in order to determine nutrient inputs in this region. While δ¹³C data did not display any significant trends spatially, δ¹⁵N values of the majority of biota exhibited a strong …

Environmental Influences On Bacterio-Phytoplanktonic Coupling And Bacterial Growth Efficiency In A Sub-Tropical Estuary, Rachel Kotkowski

FIU Electronic Theses and Dissertations

Bacterio-phytoplanktonic coupling and bacterial growth efficiency (BGE) measurements were used to analyze microbial trophic dynamics and the influence of environmental factors in Florida Bay, Florida. Phytoplankton gross primary productivity (GPP) was measured using 24-hour in situ oxygen incubations; bacterial productivity (BP) was measured using ³H- thymidine incorporation. Weak bacterio-phytoplanktonic coupling was observed over the sampling period. BP was more influenced by local total nitrogen concentrations while GPP was more evenly distributed. BGE rates were low but consistent with marine and estuarine ecosystems worldwide. Results suggest that bacterioplankton growth in Florida Bay is relatively uncoupled from phytoplankton production, which may …

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 …