Life Sciences Commons^™

Influence Of Energy Availability On The Carbon Isotopes Of Methane And Biomarkers During Hydrogenotrophic Methanogenesis, Tran Nguyen

Theses and Dissertations

Signatures of organic molecules in the environment are widely used to identify microbial metabolic processes and to track the cycling of carbon. The lipid biomarkers of methane cycling archaea are of particular interest as they are unique, preserved over geologic time scales, and reflect processes that impact an important greenhouse gas. Their isotopic compositions have been used to distinguish regions where archaea produce and anaerobically consume CH4. Previous work has demonstrated that energy availability impacts the stable carbon isotopes of CH4 during microbial synthesis from H2 and CO2. Here, we investigated whether this relationship could be extended to lipids and …

Determining The Subsidence Rate Of The Cascade Seamount Using Strontium Isotope Stratigraphy, Sarah L. Vorsanger

Theses and Dissertations

The Cascade Seamount is a wave-planated feature located on the microcontinent of the East Tasman Plateau (ETP). The minimum subsidence rate of the Seamount and the ETP can be estimated by dividing the present-day depth of the wave-cut surface (640 m) by the age of Cascade Seamount basalts as determined by potassium-argon (K-Ar) dating (33.4 and 36 Ma). This approach yields a subsidence rate of 18 m/Myr. However, a significantly more rapid subsidence rate of the ETP since the Eocene-Oligocene transition has been proposed based on sedimentological and biostratigraphic techniques. The late Eocene paleodepths determined by Stickley et al. (2004) …

Climate Metric Coherence: Stationarity Of The Relationships Between North Pacific Climate Indices And Ecological Processes In The Gulf Of Alaska, Michael Opiekun

Theses and Dissertations

The Pacific Decadal Oscillation (PDO) has been used to characterize the dominant basin-scale climate variability, in the North Pacific. The PDO index has been correlated to Pacific salmon (Oncorhynchus spp.) population dynamics in the Gulf of Alaska (GOA) during the late 1900s, but the stationarity of the statistical relationships between salmon production and the basin-scale index (and between the regional physical processes and the basin-scale index) has not been quantified. A change in the relationship between the PDO and salmon catches has been noted during the late 1980s, motivating further investigation of variability in climate and ecosystem properties during this …

Phenotypic Response Of Marine Cryptophytes To Varying Spectral Irradiance, Kristin M. Heidenreich

Theses and Dissertations

Cryptophytes are eukaryotic algae found in a variety of aquatic ecosystems, that vary in the color of light available for photosynthesis. This algal division displays a diversity in necessary photosynthetic pigments, possessing either phycoerythrin (Cr-PE; “pink”) phycocyanin (Cr-PC; “green”). According to the theory of complementary chromatic adaptation, this diversity should help maximize absorption of light within natural environments. The objective of this study was to determine if pigmentation related to growth performance in environments of differing spectral irradiance. Eight species of marine cryptophytes (5 Cr-PE and 3 Cr-PC species) were grown under four different spectral light environments. Growth rates, cellular …

Marine Tardigrades From South Carolina, Usa, Paul J. Bartels, Lilvia J. Bradbury, Diane R. Nelson

Journal of the South Carolina Academy of Science

Until now, there have been only three studies of marine tardigrades from South Carolina, USA. The Fall 2015 invertebrate zoology class from Warren Wilson College collected four sediment samples from Huntington Beach State Park: shallow beach sand, deep beach sand, shallow salt marsh sediment, and deep salt marsh sediment. No tardigrades were found in the salt marsh, but two species were found in the beach samples. Batillipes pennaki Marcus, 1946 was found in shallow and deep beach sand, and three specimens of a potentially new species of Stygarctus Schulz, 1951 were found in the deep beach sand at groundwater level. …

Causes And Consequences Of Individual Phenotypic Differences In Brachyuran Crabs With A Focus On Behavior, Benjamin A. Belgrad

Theses and Dissertations

Individual variation defines almost every morphological, physiological, and behavioral aspect of populations and is a fundamental component of many ecosystem processes. Recent work indicates that accounting for these individual differences can enhance our ability to predict community responses to environmental disturbances which is becoming increasingly important in an era of extraordinary global change. However, our understanding of how different individual characteristics are connected to each other and governed by the environment remains limited.

This study sought to evaluate the relationship between individual behavior, physiological condition, and local habitat for Brachyuran crabs as well as the subsequent strength of their predator-prey …

The Energetic Consequences Of Temperature Variation And Sequential Autotomization For The Stone Crab, Menippe Spp., Eric R. Hancock

Theses and Dissertations

The stone crab, Menippe spp., is harvested in a claw only fishery along the Gulf and southeastern Atlantic coasts of the United States. As climate change continues to warm these areas, crabs are forced to cope with higher water temperatures and lower dissolved O2 concentrations. These altered environmental conditions may influence crab energetics by altering both energy intake and expenditure. To inform fishery sustainability as well as prepare for a potential range expansion of the crab, this study investigates the energetic intake and expenditure of individual stone crabs. Crabs were found to respire 80 and 69% more following the loss …

Differential Response Of Coral Symbiotic Dinoflagellates To Bacterial Toxins That Produce Bleaching In Stony Corals, Diego L. Gil-Agudelo, Yael Ban-Haim, Eugene Rosenberg, Garriet W. Smith

Journal of the South Carolina Academy of Science

Bleaching of corals and other organisms with symbiotic zooxanthellae is a worldwide phenomenon with increasing importance due to global warming scenarios. Bleaching has been historically related to changes in the environment, especially water temperature increase, that stress corals and provoke the release of zooxanthellae. The discovery of Vibrio shilonii, a bacterium causing bleaching under thermal stress in corals of the Mediterranean Sea has changed our thinking about the cause (or explanation) for bleaching of corals worldwide. During this study, we evaluated the effect of a proline rich toxin, extracted from Vibrio shilonii, on zooxanthellae obtained from: Oculina patagonica from the …

Air- Sea Interactions And Ocean Dynamics In The Southwest Tropical Indian Ocean, Jessica Maureen Burns

Theses and Dissertations

The Southwest Tropical Indian Ocean (SWTIO) features a unique, seasonal upward lift of the thermocline, which is known as the Seychelles-Chagos Thermocline Ridge (SCTR; 55°E-65°E, 5°S-12°S). It is known that a high correlation exists between the depth of the thermocline and sea surface temperature (SST; a key ingredient for tropical cyclogenesis). With a particular focus on 2012/2013, this study reveals the dynamic properties of the SCTR that play an important role in the modulation of tropical cyclones in the SWTIO. Phenomena including Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) are also well correlated to cyclogenesis through changes …

Marine Phosphorus Biogeochemistry Ecological Insights From Analytical Chemistry, Douglas W. Bell

Theses and Dissertations

The supply of phosphorus (P) directly impacts the growth and speciation of marine microbes (i.e., phytoplankton, bacteria, Archaea). In turn, microbial communities shape the magnitude and rate of marine biogeochemical cycles, ultimately affecting global climate and food production. This dynamic reflects the continuum of temporal and spatial scales at which the marine P cycle operates. However, linking multiple scales of cycling remains a consistent challenge. The primary objective of my dissertation was to gain insight into marine P biogeochemistry, by means of analytical chemistry, at the molecular and environmental scales of cycling. The first component of my research was to …

Molecular Exploration Of Bioavailable Dissolved Organic Matter Across Aquatic Ecosystems, Yuan Shen

Theses and Dissertations

Dissolved organic matter (DOM) in aquatic ecosystems is a large reservoir of reduced carbon that is mostly resistant to degradation. A small fraction of DOM cycles relatively quickly and is biologically utilized on timescales of days to months. This bioavailable DOM (BDOM) supports aquatic food webs, drives major elemental cycles, and is coupled to atmospheric CO2. Despite wide-ranging importance, bioavailability of DOM and its linkages to ecosystem properties (e.g., primary production, nutrients) are poorly characterized, particularly at the ecosystem level. Bioassay experiments are commonly used to determine BDOM, but this approach alters conditions and has limited spatial and temporal coverage. …

Wind Driven Shelf Circulation: Effects Of Shoreline Orientation, Bathymetry, And Surface Cooling, Xiaodong Wu

Theses and Dissertations

The dynamic region extending from the inner- to outer-shelf is the nearshore region where an accurate understanding of the development of cross-shore flows is important as they control the exchange of constituents (e.g., pollutants, larvae, heat and biota) between the coastline and the open ocean. These flows are driven by a variety of forces, including wind and buoyancy. The wind forcing relevant to shelf circulation broadly falls within the synoptic scale of storm events, consisting of frontal systems (cold and warm fronts) and tropical storms. The buoyancy on the shelf is characterized by a vertical stratification or a pronounced cross-shore …

Development Of A Sandwich Hybridization Assay For The Harmful Cyanobacteria Microcystis Spp., Nicole M. Dearth

Theses and Dissertations

Cyanobacteria are responsible for the largest number of harmful blooms (HABs) worldwide. HABs caused by the genus Microcystis pose public health threats because they often occur within close proximity to humans and produce microcystin (hepatotoxin), which can contaminate drinking water and recreational areas. Novel molecular techniques facilitate monitoring, ‘early warnings’ of HAB events, and appropriate management responses. Sandwich hybridization assay (SHA), the technique considered here, directly (no amplification) identifies and quantifies planktonic species using ribosomal RNA (rRNA)-targeted oligonucleotides. This project developed SHA for Microcystis 16S rRNA and validated the assay using laboratory cultures and samples from a multi-specific cyanobacteria bloom …

The Influence Of Phytoplankton Size And Community Composition On Carbon Cycling And Planktonic Food Webs In The Sargasso Sea, Bridget Elise Cotti-Rausch

Theses and Dissertations

The Sargasso Sea is a dynamic physical environment located in the western North Atlantic where strong seasonal variability combines with forcing by mesoscale (~100 km) eddies. These drivers determine nutrient, light, and temperature regimes, and ultimate the size, composition and productivity of the phytoplankton community. My general objective was to determine how the structure and function of planktonic communities affected carbon export from the surface ocean in the Sargasso Sea. On four cruises (2011 and 2012; one eddy per cruise), I investigated links between water column structure, plankton community composition, size, and primary production (PP). I then combined PP data …

Coastal Wetland Response To Sea-Level Rise In A Fluvial Estuarine System, Karim Alizad, Scott C. Hagen, James T. Morris, Stephen C. Medeiros, Matthew V. Bilskie, John F. Weishampel

Faculty Publications

Coastal wetlands are likely to lose productivity under increasing rates of sea-level rise (SLR). This study assessed a fluvial estuarine salt marsh system using the Hydro-MEM model under four SLR scenarios. The Hydro-MEM model was developed to apply the dynamics of SLR as well as capture the effects associated with the rate of SLR in the simulation. Additionally, the model uses constants derived from a 2-year bioassay in the Apalachicola marsh system. In order to increase accuracy, the lidar-based marsh platform topography was adjusted using Real Time Kinematic survey data. A river inflow boundary condition was also imposed to simulate …

Coastal Wetland Response To Sea-Level Rise In A Fluvial Estuarine System, Karim Alizad, Scott C. Hagen, James T. Morris, Stephen C. Medeiros, Matthew V. Bilskie, John F. Weishampel

Faculty Publications

Coastal wetlands are likely to lose productivity under increasing rates of sea-level rise (SLR). This study assessed a fluvial estuarine salt marsh system using the Hydro-MEM model under four SLR scenarios. The Hydro-MEM model was developed to apply the dynamics of SLR as well as capture the effects associated with the rate of SLR in the simulation. Additionally, the model uses constants derived from a 2-year bioassay in the Apalachicola marsh system. In order to increase accuracy, the lidar-based marsh platform topography was adjusted using Real Time Kinematic survey data. A river inflow boundary condition was also imposed to simulate …

Assessing The Effects Of The Mud Snail, Ilyanassa Obsoleta, On The Benthic Microalgal Community In A Pristine Saltmarsh, Miranda Gore

Theses and Dissertations

Saltmarshes are among the most productive ecosystems globally. At North Inlet estuary, South Carolina, about one third of the primary production comes from benthic microalgae. During the tidal cycle, mobile microalgae vertically migrate through the upper 3 mm of sediment. At low tide, algae are vulnerable to a variety of grazers, including the mud snail, Ilyanassa obsoleta, which is abundant in tidal creeks. Many species of intertidal snails have been shown to significantly alter the community structure and density of microalgae within the sediment. The purpose of this study was to determine how I. obsoleta affects the benthic microalgae community …

Bioavailability Of Dissolved Organic Matter In The North Inlet Estuary, Andrew Mason Gaines Banks

Senior Theses

Dissolved organic matter (DOM) is an important source of carbon and energy for microbial food webs in estuaries. The export of DOM from estuaries to the coastal ocean influences shelf productivity and biogeochemical cycles. Chromophoric dissolved organic matter (CDOM) is an important component of the DOM pool that absorbs light, and is photoreactive. There are various optical properties of CDOM that can be used to indicate the sources of DOM, such as whether or not it is derived from terrestrial or marine environments. In this study, the sources and bioavailability of DOM were characterized in the North Inlet estuary near …

Dynamic Simulation And Numerical Analysis Of Hurricane Storm Surge Under Sea Level Rise With Geomorphologic Changes Along The Northern Gulf Of Mexico, Matthew V. Bilskie, S. C. Hagen, Karim Alizad, S. C. Medeiros, D. L. Passeri, H. F. Needham, A. Cox

Faculty Publications

This work outlines a dynamic modeling framework to examine the effects of global climate change, and sea level rise (SLR) in particular, on tropical cyclone-driven storm surge inundation. The methodology, applied across the northern Gulf of Mexico, adapts a present day large-domain, high resolution, tide, wind-wave, and hurricane storm surge model to characterize the potential outlook of the coastal landscape under four SLR scenarios for the year 2100. The modifications include shoreline and barrier island morphology, marsh migration, and land use land cover change. Hydrodynamics of 10 historic hurricanes were simulated through each of the five model configurations (present day …

The Response Of Runoff And Sediment Loading In The Apalachicola River, Florida To Climate And Land Use Land Cover Change, Paige A. Hovenga, Dingbao Wang, Stephen C. Medeiros, Scott C. Hagen, Karim Alizad

Faculty Publications

The response of runoff and sediment loading in the Apalachicola River under projected climate change scenarios and land use land cover (LULC) change is evaluated. A hydrologic model using the Soil and Water Assessment Tool was developed for the Apalachicola region to simulate daily runoff and sediment load under present (circa 2000) and future conditions (2100) to understand how parameters respond over a seasonal time frame to changes in climate, LULC, and coupled climate/LULC. The Long Ashton Research Station-Weather Generator was used to downscale temperature and precipitation from three general circulation models, each under Intergovernmental Panel on Climate Change (IPCC) …

Tidal Hydrodynamics Under Future Sea Level Rise And Coastal Morphology In The Northern Gulf Of Mexico, Davina L. Passeri, Scott C. Hagen, Nathaniel G. Plant, Matthew V. Bilskie, Stephen C. Medeiros, Karim Alizad

Faculty Publications

This study examines the integrated influence of sea level rise (SLR) and future morphology on tidal hydrodynamics along the Northern Gulf of Mexico (NGOM) coast including seven embayments and three ecologically and economically significant estuaries. A large-domain hydrodynamic model was used to simulate astronomic tides for present and future conditions (circa 2050 and 2100). Future conditions were simulated by imposing four SLR scenarios to alter hydrodynamic boundary conditions and updating shoreline position and dune heights using a probabilistic model that is coupled to SLR. Under the highest SLR scenario, tidal amplitudes within the bays increased as much as 67% (10.0 …

Development And Application Of Foraminiferal Carbonate System Proxies To Quantify Ocean Acidification In The California Current, Emily B. Osborne

Theses and Dissertations

The oceanic uptake of anthropogenic carbon has mitigated climate change, but has also resulted in a global average 0.1 decline in surface ocean pH over 20th century known as ocean acidification. The parallel reduction in carbonate ion concentration ([CO32-]) and the saturation state of seawater (Ω) has caused many major calcium carbonate-secreting organisms such as planktonic foraminifera to exhibit impaired calcification. We develop proxy calibrations and down core records that use calcification and geochemical characteristics of planktonic foraminifera as proxies for the marine carbonate system. This study focuses specifically on the surface ocean chemistry of the California Current Ecosystem (CCE), …

Utilization Of Satellite-Derived Salinity To Study Indian Ocean Climate Variability, Joseph Matthew D’Addezio

Theses and Dissertations

For several decades, researchers have explored Indian Ocean climate variability primarily using numerical models because of a lack of observations. Remote sensing technology has helped overcome this scarcity of observational data, but satellite-derived salinity has only been recently made available by the ESA’s Soil Moisture and Ocean Salinity (SMOS, operating since November 2009-present) and NASA’s Aquarius SAC-D (operated during June 2011-June 2015) satellites. Along with the Lagrangian in situ Argo floats array, these new datasets may be used to validate widely used numerical models, such as the HYbrid Coordinate Ocean Model (HYCOM), and also potentially observe new salinity phenomena that …

Applicability Of Lidar Technology In Saltmarshes: Landscape-Scale Predictive Models To Local-Scale Biomass Estimation, James Dean Edwards Jr.

Theses and Dissertations

The management of saltmarshes requires detailed knowledge of the underlying processes driving their distribution in both time and space to make appropriate management decisions. With most of the world’s population living in the coastal zone and rising sea levels, one of our most important natural resources in the coastal zone faces increasing threat of collapse. This study uses the current state of Light Detection and Ranging (LiDAR) technology to model and predict saltmarsh distribution at a landscape-scale and provide evidence that a terrestrial laser scanner (TLS) can be used to estimate saltmarsh biomass for inclusion into existing models.

Land cover …

Mislabeling Of Commercial Atlantic Cod (Gadus Morhua) Products In Spain, Joshua Helgoe

Theses and Dissertations

The mislabeling of commercial fish products is a pervasive, worldwide problem. Most consumers of seafood are unaware this issue directly affects them and can even have negative impacts on their health. Mislabeling occurs when a product’s label is inconsistent with its content. Although mislabeling can be unintentional, deliberate mislabeling is a more common trend to increase profits and/or bypass fishing regulations - a form of economic fraud. Unfortunately, oversight, enforcement, and research are vastly insufficient in relation to the global scale of the problem. In order to add to the small knowledge base on European mislabeling rates, determine if overfished …

Biodegradation Of Highly Weathered Deepwater Horizon Oil, Joel T. Bostic

Theses and Dissertations

Oil from the Deepwater Horizon (DwH) spill continues to be found on beaches five years post-spill. Understanding the role of microbes in removing DwH oil from sandy beaches is necessary to elucidate the fate of DwH oil in the coastal zone. Oiled sand patties and non-oiled sand were collected from affected beaches five years post- DwH. Biomarkers in oiled sand indicated that sand patties originated from the DwH spill, however the oil was heavily weathered and dominated by oxygenated hydrocarbons. Microbial communities, as measured by phospholipid fatty acids (PLFA), were present on oiled sand patties and distinct from microbes on …

Decadal Salinity Changes In The Oceanic Subtropical Gyres And Connection To Changes In The Global Water Cycle, Bryce Andrew Melzer

Theses and Dissertations

There is evidence that the global water cycle has been undergoing an intensification over several decades as a response to increasing atmospheric temperatures, particularly in regions with skewed evaporation – precipitation (E-P) patterns such as the oceanic subtropical gyres. However, observational data (rain gauges, etc.) can be quite sparse over such areas due to the inaccessibility of open ocean regions. This study utilizes in situ data, reanalysis, and model outputs to infer interannual to decadal scale trends in surface freshwater forcing within remote, evaporation-dominated subtropical regions of the ocean as they pertain to the past and present state of the …

Global Methylation Of Dna Among Spartina Alterniflora Clones Differing In Age At North Inlet, Sc, Trenton Agrelius

Theses and Dissertations

“Brown marsh” or “sudden marsh dieback” refers to the rapid death of patches varying in size of Spartina alterniflora. In 2000 following a 100-year record drought, approximately 8,000 hectares of S. alterniflora died along the Louisiana coast, which prompted Louisiana Governor Foster to declare a state of emergency. Other cases have been documented at North Inlet, SC as well as various other marshes along the southeastern United States. Currently, there is much dispute regarding the cause of “sudden marsh dieback” but environmental stress is one of the acknowledged constants across sites. We hypothesized an alternative mechanism in which methylation of …

Viruses And Metals In Ocean Food Webs: Top-Down And Bottom-Up Effects Of Marine Viruses And Trace Elements On Marine Picophytoplankton, Brady Robert Cunningham

Theses and Dissertations

Viruses are the most numerous biological entities in the ocean, playing a key role in microbial ecology and biogeochemical cycling. In order to replicate, viruses must first infect a host and then use the host’s cellular machinery to produce new viral particles. Some of the most abundant viral hosts in the subtropical open ocean are picophytoplankton. However, picophytoplankton growth is typically constrained by nutrient availability. In many regions of the ocean, iron (Fe) is only available in very low concentrations causing growth-limitation of picophytoplankton. Interestingly, the interactions between Fe-limitation and viral infection of picophytoplankton have not been extensively studied. This …

Size-Fractionated Relationships Between Phytoplankton Production And Biomass, Luke Auman Bassett

Senior Theses

Phytoplankton are the autotrophic foundation of almost all marine ecosystems.

The flow of energy through an ecosystem is largely dependent how productivity moves through organisms of various sizes. For this reason, numerous studies have set out to quantify the respective contributions of these size-fractions to biomass and rates of primary production. This is done through field measurements of production or through mathematic models that infer production contributions from the easier field measured contributions to biomass. However, the accuracy of this method has been called into question. Can contributions to biomass really be used to accurately interpret contributions to production?

The …