Physical Sciences and Mathematics Commons^™

Iron Isotope Transformations In Saanich Inlet, Claire Onak

USF Tampa Graduate Theses and Dissertations

Iron (Fe) is required for many biogeochemical processes, with Fe bioavailability and chemistry being controlled by redox reactions that transform Fe between oxidation states and dissolved and particulate phases. In oxic seawater, Fe is present in the Fe(III) oxidation state, mainly as Fe oxyhydroxides. Under anoxic marine conditions, such as margin sediments under oxygen minimum zones or restricted basins with anoxic bottom water, Fe(III) is reduced to Fe(II), which is highly soluble and can be present at high concentrations ([Fe]). Fe isotope ratios (δ56Fe relative to IRMM-14) can be used to characterize Fe redox transformations, constrain Fe sources of Fe …

Labile Dissolved Nickel (Ni) Concentrations In The North Pacific, Calyn M. Crawford

USF Tampa Graduate Theses and Dissertations

Nickel (Ni) is an important micronutrient for phytoplankton and bacteria that serves as a required co-factor in several metalloenzymes. Despite these known biological uses, total dissolved Ni concentrations remain elevated in global surface waters, in contrast to the surface depletion commonly observed for macronutrients and other nutrient-type trace elements. A prevailing hypothesis for the muted depletion of dissolved Ni concentrations in surface waters is that dissolved Ni in seawater is not in a bioavailable form. The chemical lability of Ni in seawater provides insight into Ni speciation and bioavailability, but few measurements have been made in the open ocean to …

Stable Isotope Analysis On Yellowfin And Blackfin Tuna Eye Lenses Reveals Life History Patterns In The Gulf Of Mexico, Kylee M. Rullo

USF Tampa Graduate Theses and Dissertations

Spatial geography, ontogenetic movement, and trophic patterns of mobile species are key elements of effective marine resource management. A number of methods are currently available for tracking movements of pelagic migratory species, including the use of conventional and electronic tags. However, tagging campaigns can take years to provide useful data, can be expensive, and only capture a portion of a fish’s lifetime. For this project, I used stable-isotopic ratios of nitrogen (δ15N) and carbon (δ13C) in metabolically inert, chronologically-layered fish-eye lenses to explore lifetime movement and trophic patterns of yellowfin tuna (Thunnus albacares) and blackfin tuna (Thunnus atlanticus) in the …

Meta-Analysis Of United States Seabird Populations Based On Ocean Biodiversity Information System (Obis) Records (1965–2018), Savannah Hartman

USF Tampa Graduate Theses and Dissertations

Understanding the distribution of organisms is an important priority for society as we live through ecosystem transformations that threaten the well-being of all organisms. I have approached the dynamic and complex issue of studying biodiversity by using open-access seabird data collected along the Americas since the 1960s. I explained how these data have changed over time and space, how certain species populations could have shifted over time, and possible correlations between this potential geographic change and select environmental variables.

In Chapter 2 I evaluated the suitability of the open-access data archive Ocean Biodiversity Information System (OBIS) for supporting detailed inquiry …

Exploring The Impact Of Eddies On Southern Ocean Biogeochemical Structure Using Bgc-Argo Float Observations, Nicola J. Guisewhite

USF Tampa Graduate Theses and Dissertations

The Southern Ocean plays a crucial role in global ocean circulation, and global heat and nutrient transport. However, this region is both distant and dangerous and is therefore largely under-sampled and understudied. Methods to fill in biogeochemical data-gaps include using limited in-situ data in models to output biogeochemical property estimates, but a number of recent studies have raised concerns about how most Southern Ocean models do not resolve eddies. Eddies are known to impact biogeochemistry around the globe but little is known about their impact in the Southern Ocean. This study examines temperature, salinity, oxygen, nitrate, and dissolved inorganic carbon …

Environmental Chemical Analysis Method Optimization And Application To Northwest Cuban Marine Sediment, Thea R. Bartlett

USF Tampa Graduate Theses and Dissertations

A method for gas chromatography tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode has been optimized to quantify 250 compounds of a variety of compound classes such as polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, organochlorinated pesticides, polychlorinated biphenyls, biomarkers (hopanes, steranes, tri-aromatic steroids, and fecal sterols), aliphatic hydrocarbons, and plastic additives. This method was validated based on available QA/QC standards using several environmental samples, both sediment and biota, and standard reference materials. This contaminant-focused method can be used as a forensic geochemistry tool to evaluate oil contamination and other contaminant histories in future research studies. When applied to …

Stable Isotope Analysis Of Doryteuthis (Amerigo) Pealeii Eye Lenses To Determine Migratory Patterns In The Eastern Gulf Of Mexico Using Statoliths For Age Determination, Hannah M. Schwaiger

USF Tampa Graduate Theses and Dissertations

Doryteuthis (Amerigo) pealeii is a common fisheries squid that occurs in the Gulf of Mexico (GoM) and along the east coast of the United States. These squid are an important link in the food web, linking higher and lower trophic positions (Madsen et al., 2007), and they are also used for human consumption. The migration patterns of D. pealeii populations in the northwestern North Atlantic have been thoroughly studied when compared to those in the GoM. This research aims to combine statolith aging and stable isotope analysis to enhance the understanding of D. pealeii migration patterns throughout their short, sub-annual …

Time Series Analysis Of Pseudo-Nitzschia Species Composition, Domoic Acid, And Environmental Conditions In The Gulf Of Maine From 2013-2020, Christina Chadwick

USF Tampa Graduate Theses and Dissertations

Phytoplankton are abundant in both fresh and marine waters and can form harmful algal blooms (HABs) by producing potent toxins that have devastating effects on human, wildlife, and economic health. The HAB-forming diatom genus, Pseudo-nitzschia, occurs globally and approximately half of the 59 currently identified species can produce the neurotoxin, domoic acid (DA). DA accumulates in shellfish and finfish and can cause Amnesic Shellfish Poisoning (ASP) in humans and DA Poisoning (DAP) in several species of wildlife, resulting in severe neurological dysfunction and mortality. Along with these health threats, DA toxicity is a major economic threat for shellfish and fish …

The Effects Of Temperature And Oxygen Availability On Aerobic Performance In Three Coastal Shark Species; Squalus Acanthias, Carcharhinus Limbatus, And Carcharhinus Leucas, Alyssa M. Andres

USF Tampa Graduate Theses and Dissertations

Anthropogenically driven climate changes are altering marine habitats globally. Rising sea surface temperatures and coastal eutrophication, arising from global warming and coastal nutrient loading, have resulted in progressive ocean deoxygenation. This may restrict available habitat of marine organisms as studies suggest that the balance between metabolic oxygen demand and environmental supply plays an important role in limiting viable habitat and species fitness. As ectothermic predators, with temperature-dependent metabolism and high metabolic demands, coastal shark species may be susceptible to shifts in ocean temperature and oxygen. Such environmental changes may alter metabolic performance and ultimately success and survival within shark habitat. …

Zooplankton Biodiversity In The Northeast Gulf Of Mexico And On The West Florida Shelf From 2005 - 2014, Megan Ferguson

USF Tampa Graduate Theses and Dissertations

Zooplankton abundance and biodiversity was measured in the northeast Gulf of Mexico (NEGoM) and on the West Florida Shelf. Bongo net samples were collected between May 2005 to September 2009 through the SEAMAP program, and between July 2010 to August 2014 through the C-IMAGE program. Calanoid copepods were the most abundant zooplankton group in most of the samples collected, but ostracods, larvaceans, and chaetognaths were also abundant. Shannon and Inverse Simpson indices were calculated for all zooplankton samples and generally showed similar trends, but only Shannon indices were used for statistical analyses. In the winter and spring there were significant …

Elucidating The Sources Supplying Aerosol Iron, Zinc, And Cadmium To The Surface Of The North Pacific Ocean With Stable Isotopes, Zach B. Bunnell

USF Tampa Graduate Theses and Dissertations

Transition metals, such as iron (Fe), zinc (Zn) and cadmium (Cd), are found at just trace amounts within the global oceans yet are vital for many biological functions of phytoplankton. As a result, these metals influence the ocean’s efficacy for carbon sequestration. Atmospheric dust is the primary input of Fe to various surface waters and may also supply Zn and Cd to oligotrophic surface waters. Here, I present Fe, Zn, and Cd isotope data from the US North Pacific GEOTRACES Section GP15 (Alaska-Tahiti) from the low-dust season (Sept. – Nov. 2018). Using this data and aerosol enrichment factors, I show …

Chronological Accumulation Of Microplastics In The Gulf Of Mexico And Their Acute Effects On Coral Bleaching, Martina M. Plafcan

USF Tampa Graduate Theses and Dissertations

Microplastics have accumulated in the environment since plastic production began. They have spread to all areas of the globe from marine trenches to mountains and they can be harmful to organisms. However, research on microplastics has only recently begun so it is unclear how they have changed over time in many regions of the ocean and how current oceanic concentrations might affect marine life. Additionally, organisms such as corals are under stress and have been declining due to climate change, so it is not yet known if microplastics exacerbate these threats. My thesis addressed these gaps in the literature by …

Determinations Of Chemical Equilibria In Natural Waters Using Spectrophotometric Techniques, Katelyn M. Schockman

USF Tampa Graduate Theses and Dissertations

Accurate characterizations of chemical equilibria and thermodynamic processes in natural waters are key components for assessing the current state of our global climate and predicting future changes, especially for observations of small rates of change over long time scales. One of the most important chemical systems in natural waters is the system of inorganic carbon species comprised of carbon dioxide (CO2), bicarbonate, and carbonate. The bicarbonate dissociation constant, K2, describes the relationship between pH and the relative concentrations of bicarbonate and carbonate ions at thermodynamic equilibrium. The carbonate/bicarbonate equilibrium quotient is required in nearly all CO2 system calculations relevant to …

Empirical And Modeled Δ13c And Δ15n Isoscapes In The Gulf Of Mexico And Their Application To Fish Eye Lens Migration Studies, Brianna Michaud

USF Tampa Graduate Theses and Dissertations

Isoscapes are depictions of the spatial patterns of isotopic values in a given area. Isoscapes can be created using measurements form samples (empirical isoscapes) or using statistical models of spatial isotopic variation (modeled isoscapes). Isoscapes have a wide variety of potential applications though, in the realm of marine ecology, they are most often used infer ecological processes, food web linkages, the origin of samples, and the movements of marine organisms.

However, to use isoscapes for these applications, it is necessary to have isoscapes at spatial scales relevant to the application in question. It is also necessary to have isoscapes that …

Quantitative Assessment Of The Trophic Ecology Of The Oceanic Ctenophore, Bolinopsis Infundibulum, In Monterey Bay, California, Victoria C. Scriven

USF Tampa Graduate Theses and Dissertations

Bolinopsis infundibulum is a wide-ranging, ubiquitous ctenophore whose fragile nature makes the collection of specimens and quantification of key predator-prey activities in controlled laboratory experiments, challenging. Thus, in situ methods often represent the best means for data collection. However, while present in surface waters, these animals can also be abundant at depths well beyond those attainable by divers. As a result, very little empirical data exist over the depth range of their natural habitats which limits our ability to assess key predator-prey interactions needed to assess their ecological role in midwater food webs. Working in Monterey Bay, California, remotely operated …

Riverine And Estuarine Co2-System Studies On The West Coast Of Florida, Christopher S. Moore

USF Tampa Graduate Theses and Dissertations

Coastal and estuarine acidification impacts ecosystem health and economic resources and has both natural and anthropogenic components (Cai et al., 2021). Riverine input is one of several important factors that can influence acidification in coastal ecosystems. Rivers disgorging into coastal environments can create strong gradients, both spatial and temporal, that make accurate CO2-system characterization challenging. The work described in this thesis provides a baseline CO2-system study of four major rivers that flow into Tampa bay with an emphasis on seasonal change. As a second objective, this thesis examines the effects of HgII additions on CO2-system measurements in organic-rich estuarine waters. …

From River To Sea: Improving Carbon System Measurement Methods For Use In Rivers, Estuaries, And Oceans, Ellie Hudson-Heck

USF Tampa Graduate Theses and Dissertations

Over the last 30 years, spectrophotometric methodologies have been developed, with increasing rigor, to accurately measure all four carbon system parameters: total alkalinity (A_T), total carbon (C_T), partial pressure of CO₂ (pCO₂), and pH. Spectrophotometric measurements of carbon system parameters rely on quantitative characterizations of the response of sulfonephthalein indicator dyes (e.g., meta-cresol purple (mCP), thymol blue (TB), and bromocresol purple (BCP)) to changing solution pH, as well the response of indicator physical-chemical characteristics to key environmental variables (salinity (S_P), temperature (T), and pressure). Until recently, the physical-chemical properties …

Modeling Early Life: Ontogenetic Growth And Behavior Affect Population Connectivity In Gulf Of Mexico Marine Fish, Kelly Vasbinder

USF Tampa Graduate Theses and Dissertations

This dissertation is an examination of growth, behavior, and dispersal during the early life stages of marine fishes in the Gulf of Mexico. Understanding movements of early life stages is a key part of managing exploited fish populations. Position in the water column can impact larval dispersal, since it determines those currents to which larvae are exposed. First, I investigated the relationship between length and age in early life stages of marine fishes. I found that demersal fish taxa tend to be represented by exponential models, while pelagic fish tend to be represented by linear models. I suggest this may …

Analytical Methods And Critical Analyses Supporting Thermodynamically Consistent Characterizations Of The Marine Co2 System, Jonathan D. Sharp

USF Tampa Graduate Theses and Dissertations

Chemical equilibria describing the unique behavior of gaseous and ionic forms of dissolved carbon dioxide (CO₂) in seawater comprise what is known as the marine CO₂ (or carbonate) system. Observations of the marine CO₂ system with high degrees of accuracy, reproducibility, spatial coverage, and temporal resolution are critical for evaluating natural cycles of carbon within the Earth system, as well as chemical and biological responses to anthropogenic CO₂ emissions.

One component of the CO₂ system is the carbonate ion (CO²−₃), a dissolved ion that is produced when carbonic acid (H …

A Process-Based Approach To Evaluating The Role Of Organic Ligands In Trace Metal Cycling In The Marine Environment, Travis Mellett

USF Tampa Graduate Theses and Dissertations

In addition to control by major nutrient elements (nitrogen, phosphorous, and silicon) growth and community composition of marine phytoplankton is also regulated by trace element nutrients (iron, copper, manganese, zinc, cobalt, nickel, and cadmium). Of these, iron is the most influential in the modern ocean, regulating phytoplankton growth and carbon export in high-nutrient low-chlorophyll regimes and exerting an important control on the marine nitrogen cycle through its role in di-nitrogen fixation. The distributions of these metals has the capacity to control primary production and phytoplankton community composition through differences in cellular quotas or metal sensitivities amongst species. The relationship between …

Investigating The Isotope Signatures Of Dissolved Iron In The Southern Atlantic Ocean, Brent A. Summers

USF Tampa Graduate Theses and Dissertations

Iron (Fe), used as a cofactor in nitrogen fixation and photosynthesis by oceanic microorganisms, has extremely low dissolved concentrations in the surface ocean, leading to widespread limitation of phytoplankton growth. Dissolved Fe isotope ratios (δ56Fe) have been shown to be useful in helping to quantify the sources and cycling of Fe in the oceans if Fe source signatures and fractionation processes are well understood. Here, this thesis presents data from GEOTRACES section GA10W, and investigate the isotopic signature of sediment-derived dissolved Fe from the South Atlantic margins. My results show that there are both shallow (δ56Fe of -0.2‰) and deep …

Polycyclic Aromatic Hydrocarbon Exposure, Hepatic Accumulation, And Associated Health Impacts In Gulf Of Mexico Tilefish (Lopholatilus Chamaeleonticeps), Susan M. Snyder

USF Tampa Graduate Theses and Dissertations

Following the 2010 Deepwater Horizon oil spill, systematic demersal longline surveys were conducted throughout the Gulf of Mexico (GoM) continental shelf to evaluate polycyclic aromatic hydrocarbon (PAH) exposure, hepatic accumulation, and health indices in demersal fishes. Tilefish (Lopholatilus chamaeleonticeps) were chosen as a target species due to high vulnerability to environmental disturbance, commercial importance, Gulf-wide distribution, and documented high exposure to PAHs post-Deepwater Horizon. Over 200 Tilefish were sampled in the north central GoM at repeat stations from 2012 to 2017, and from the northwest GoM, southwest GoM, Bay of Campeche, and Yucatán Shelf over years 2015 and 2016. Tilefish …

Large Thecosome Pteropods Of The Northern Gulf Of Mexico: Species Abundance, Spatial And Vertical Distribution With A Temporal Comparison Of Shell Thickness, Sarah M. Shedler

USF Tampa Graduate Theses and Dissertations

Large thecosome pteropods have a significant role in the pelagic ecosystem of the northern Gulf of Mexico (GoM). This research analyzed species abundances, vertical and horizontal distributions, and trends in shell thickness between 2011 and 2015. Pteropod samples were collected following the 2010 Deepwater Horizon oil spill by two midwater sampling programs: the Offshore Nekton Sampling and Analysis Program (ONSAP, 2011) and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND, 2015). All samples were collected using a 10-m2 Multiple Opening/Closing Net and Environmental Sensing System (MOC10) midwater trawl, with 3-mm mesh size. This gear sampled five discrete …

Testing The Efficacy Of Recompression Tools To Reduce The Discard Mortality Of Reef Fishes In The Gulf Of Mexico, Oscar E. Ayala

USF Tampa Graduate Theses and Dissertations

In order to enhance the recovery of overfished stocks, fishery managers have implemented increasingly restrictive harvest regulations. However, discarded fish are susceptible to mortality from barotrauma when retrieved from depth. Venting tools are commonly used to enable fish to return to their depth of capture. An alternative method has been developed that involves the rapid descent of fish to their depth of capture to reduce buoyancy. In the Gulf of Mexico, the released portion of Red Snapper (Lutjanus campechanus) and Red Grouper (Epinephelus morio) has exceeded 80% of total catch. I tested the survival of these two economically important species …

Investigation Of Retention Versus Export Of Planktonic Fish Eggs In The Northeastern Gulf Of Mexico, Bich Vi Viviane Nguyen

USF Tampa Graduate Theses and Dissertations

Planktonic fish eggs can be reliably identified with DNA barcoding, and their distribution and abundance can be monitored. Passive drifting fish eggs can be advected by ocean currents and as a result, can either be locally retained or exported away from the West Florida Shelf (WFS). Investigating their retention or export helps in the interpretation of egg abundance trends and in understanding their distribution in long-term surveys. The present investigation was performed in two steps using a combination of biological and physical oceanographic methods. First, fish fecundity of three species (Red Snapper, Vermilion Snapper, and Sand Perch) was assessed, first, …

Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, Amy A. Wallace

USF Tampa Graduate Theses and Dissertations

The present research examined the viability and utility of eye lenses as a source of lifetime stable-isotope records in fish. It is presented in three sections. The first section compared bulk isotopic variation (bulk analysis) within fish eye-lenses at two temporal resolutions and compared patterns obtained from left and right eyes. The first temporal resolution was lower in an attempt to expose broad-scale isotopic changes during life while reducing effort and cost. This approach did reveal lifetime patterns, but tended to miss certain life events, particularly during early life. The second resolution was higher and provided detail that was missed …

Use Of Spectrofluorometry To Detect Petroleum Hydrocarbons In The Marine Environment, Mary Iris Abercrombie

USF Tampa Graduate Theses and Dissertations

The genesis of this research was the Deepwater Horizon oil spill, which discharged petroleum and gas into the Gulf of Mexico for 87 days in 2010. High-resolution fluorescence spectroscopy was employed for the detection of petroleum in seawater samples following the oil spill. Fluorescence arises from the chemical structure of π-bonding in C=C bonds, especially those in aromatic structures. Spectrofluorometry was also used to observe and track the formation of petroleum plumes in seawater undergoing controlled physical dispersion in a wave tank, both with and without the addition of chemical dispersant. Further, the changing fluorescence characteristics of a broad range …

Untapped Potential Of Gorgonian Octocorals For Detecting Environmental Change In Biscayne National Park, Florida, Usa, Selena A. Kupfner Johnson

USF Tampa Graduate Theses and Dissertations

One consequence of dramatic stony-coral loss has been recognition that gorgonian octocorals (Anthozoa: Octocorallia) have emerged among the dominant reef fauna. However, gorgonians are notoriously difficult to field-identify and consequently have been underrepresented in most monitoring efforts resulting in a lack of long-term data. The rich diversity of habitats, close proximity to the urban center of Miami, and connectivity to other areas of Florida have made Biscayne National Park an active location for reef research since its establishment in 1968. As such, a plethora of data (e.g., museum specimen and species abundance data) has been collected and stored in archives …

The Adaptations Of The Sulfur-Oxidizing, Gammaproteobacterium "Candidatus Endoriftia Persephone", Endosymbiont Of The Giant Tubeworm Riftia Pachyptila, To Hydrothermal Vent Habitat Heterogeneity, Juliana M. Leonard

USF Tampa Graduate Theses and Dissertations

The siboglinid tubeworm Riftia pachyptila is a dominant member of the deep-sea megafauna where seawater and hydrothermal vent (HTV) effluent interface and mix. It is one of the fastest growing invertebrates on land or in the sea. It does not have a digestive tract (e.g. mouth, gut, or anus), and is completely dependent on its sulfur-oxidizing endosymbiont, the Gammaproteobacterium “Candidatus Endoriftia persephone” for its nutritional requirements. This association was the first and is the most well studied among chemolithoautotrophic symbioses. “Ca. E. persephone” is a chemolithoautotrophic bacterium that oxidizes sulfide as an electron donor for energy, reduces oxygen as a …

Can Florida's Springs Coast Provide A Potential Refuge For Calcifying Organisms? Evidence From Benthic Foraminifera, Kyle E. Amergian

USF Tampa Graduate Theses and Dissertations

Florida’s Springs Coast, located in the northeast Gulf of Mexico, includes an extensive system of salt marshes that discharge millions of liters of fresh water into coastal waters daily. The chemical properties of the spring waters include high alkalinity and high calcium concentrations due to the Paleogene limestone lithology of this region of Florida. Benthic foraminifers, which are recognized as ecologically important bioindicators, occur abundantly on the shallow shelf off the Springs Coast. Based on the prevalence of the benthic foraminifer Archaias angulatus in the seagrass beds along this shallow shelf, a previous study proposed that the Springs Coast provides …