Physical Sciences and Mathematics Commons^™

Nitrogen Cycling In The Lower Chesapeake Bay And Mid- And South Atlantic Bight, Yifan Zhu

OES Theses and Dissertations

Nitrogen (N) is central to marine primary production; its availability often limits the capacity and rates of primary productivity in most of the world’s oceans. Contrastingly, estuaries frequently receive anthropogenic N loading, oftentimes resulting in eutrophication, harmful algal blooms (HABs), and substantially degraded water quality. Nutrient variability in both estuaries and oceanic regimes results from meteorological forcing and physical processes, including wind-induced, tidal, and mesoscale mixing and upwelling. In this dissertation, a comprehensive investigation of N variability and cycling and its links to physical-biogeochemical processes was conducted using time-series monitoring approaches, flux estimations, satellite imaging, biogeochemical measurements, and molecular analyses. …

Tidal Flooding In The Mid-Atlantic Region Of The Us: Water Quality Effects In The Lower Chesapeake Bay, Alfonso Macias Tapia

OES Theses and Dissertations

Many coastal areas around the globe suffer from nutrient pollution and its environmental, social, and economic consequences. Nutrient inputs can come from point (e.g., the end of a pipe) and nonpoint sources, from which the former are better constrained as sampling need only be conducted at a discharge point. Given the temporal and spatially extensive nature of tidal flooding events, they can represent another type of nonpoint source of nutrients to adjacent water bodies heretofore, unexamined and quantified. Most studies examining impacts of tidal flooding have focused on threats to resources on land, such as urban infrastructure and human health …

Biophysical Interactions Control The Progression Of Harmful Algal Blooms In Chesapeake Bay: A Novel Lagrangian Particle Tracking Model With Mixotrophic Growth And Vertical Migration, Jilian Xiong, Jian Shen, Qubin Qin, Michelle C. Tomlinson, Yinglong J. Zhang, Xun Cai, Fei Yi, Linlin Cui, Margaret R. Mulholland

OES Faculty Publications

Climate change and nutrient pollution contribute to the expanding global footprint of harmful algal blooms. To better predict their spatial distributions and disentangle biophysical controls, a novel Lagrangian particle tracking and biological (LPT-Bio) model was developed with a high-resolution numerical model and remote sensing. The LPT-Bio model integrates the advantages of Lagrangian and Eulerian approaches by explicitly simulating algal bloom dynamics, algal biomass change, and diel vertical migrations along predicted trajectories. The model successfully captured the intensity and extent of the 2020 Margalefidinium polykrikoides bloom in the lower Chesapeake Bay and resolved fine-scale structures of bloom patchiness, demonstrating a reliable …

Codar's Surface Flow At The Mouth Of The Chesapeake Bay: Relation To Bay's And Atlantic's Forcing, Shelby Kathryn Henderson

OES Theses and Dissertations

Surface currents in the lower Chesapeake Bay (CB) observed with land-based high-frequency radar antennas, or Coastal Ocean Dynamics Application Radar (CODAR), produce hourly 2D maps of current velocities used for search and rescue, pollution tracking, and fishing operations. This study analyzes the correlations between a 9-year record of surface currents measured by CODAR to coastal sea level, local wind forcing, river discharge into CB, and water transport through the Florida Straits, representing the Gulf Stream’s control on sea level along the U.S. mid-Atlantic coast. The goal of this study is to find ways to use CODAR data to detect and …

Impacts Of Multiple Environmental Changes On Long‐Term Nitrogen Loading From The Chesapeake Bay Watershed, Shufen Pan, Zihao Bian, Hanqin Tian, Yuanzhi Yao, Raymond G. Najjar, Marjorie A.M. Friedrichs, Eileen E. Hofmann, Rongting Xu, Bowen Zhang

CCPO Publications

Excessive nutrient inputs from land, particularly nitrogen (N), have been found to increase the occurrence of hypoxia and harmful algal blooms in coastal ecosystems. To identify the main contributors of increased N loading and evaluate the efficacy of water pollution control policies, it is essential to quantify and attribute the long‐term changes in riverine N export. Here, we use a state‐of‐the‐art terrestrial–aquatic interface model to examine how multiple environmental factors may have affected N export from the Chesapeake Bay watershed since 1900. These factors include changes in climate, carbon dioxide, land use, and N inputs (i.e., atmospheric N deposition, animal …

Sediment Resuspension In A Microtidal Estuary: Causative Forces And Links With Algal Blooms, Samantha C. Mcgill

OES Theses and Dissertations

After years of efforts to restore the Chesapeake Bay, bacterial levels are down and species diversity has increased, however, algal blooms (primarily dinoflagellates) persist, occurring nearly every summer. Dinoflagellates produce resting cysts that accumulate in the bottom sediments and are thought to provide seed populations for future algal blooms when they are resuspended. When estuarine sediments are advected from a bed, other materials, such as pollutants, nutrients, and organic matter are also released into the water column. Thus, resuspended sediments can contribute to the degradation of water quality, habitat, and aquatic life, and impart negative impacts on local ecosystems and …

Living Shorelines: Barriers And Promotion: Accomack County, Va, Amy Belcher, Rhiannon Bezore, Michelle Covi, Wie Yusuf

Presentations, Lectures, Posters, Reports

Living shorelines can offer shoreline protection for low energy shorelines as well as providing ecoservices such as purifying water, buffering against floods, and attracting wildlife. This report highlights key benefits, possible barriers and solutions, and ideas for their promotion. Recommendations for implementing living shorelines are included for Accomack County, Virginia to aid in increasing awareness and utilization of living shorelines.

Nutrient Controls Over Cyanobacterial Synthesis Of The Neurotoxin Β-N-Methylamino-L-Alanine (Bmaa) And Its Potential Accumulation In The Blue Crab (Callinectes Sapidus), Madeline M. Hummel

OES Theses and Dissertations

Cyanobacteria are known to produce a variety of toxins that negatively impact both aquatic and terrestrial organisms. One putative neurotoxic compound is the non-protein amino acid β-N-methylamino-L-alanine (BMAA), which has epidemiological linkages to the development of several human neurological diseases. Three cyanobacterial species thought to produce BMAA —Microcystis aeruginosa, Synechococcus bacillaris, and Nostoc sp. —were grown in nutrient replete cultures to examine its synthesis and cellular distribution over a growth cycle. Production of BMAA was also examined in nutrient (nitrogen and phosphorus) deplete cultures of Microcystis aeruginosa. In addition, natural assemblages of phytoplankton dominated by …

Estuarine Dissolved Organic Carbon Flux From Space: With Application To Chesapeake And Delaware Bays, Sergio R. Signorini, Antonio Mannino, Marjorie A.M. Friedrichs, Pierre St-Laurent, John Wilkin, Aboozar Tabatabai, Raymond G. Najjar, Eileen E. Hofmann, Fei Da, Hanqin Tian, Yuanzhi Yao

CCPO Publications

This study uses a neural network model trained with in situ data, combined with satellite data and hydrodynamic model products, to compute the daily estuarine export of dissolved organic carbon (DOC) at the mouths of Chesapeake Bay (CB) and Delaware Bay (DB) from 2007 to 2011. Both bays show large flux variability with highest fluxes in spring and lowest in fall as well as interannual flux variability (0.18 and 0.27 Tg C/year in 2008 and 2010 for CB; 0.04 and 0.09 Tg C/year in 2008 and 2011 for DB). Based on previous estimates of total organic carbon (TOCexp) exported by …

Scientific And Technical Advisory Committee Review Of The Chesapeake Bay Program Partnership’S Climate Change Assessment Framework And Programmatic Integration And Response Efforts, Maria Hermann, Scott Doney, Tal Ezer, Keryn Gedan, Philip Morefield, Barbara Muhling, Douglas Pirhalla, Stephen Shaw

CCPO Publications

[From the Executive Summary] The following report presents a synthesis of reviewer responses from the Scientific and Technical Advisory Committee’s (STAC) panel on the Chesapeake Bay Program Partnership’s Climate Change Assessment Framework (CCAF) and Programmatic Integration and Response Efforts. The enclosed findings and recommendations are in response to the 16 questions delivered to the panel (Appendix A).

In summary, given the current state of knowledge, the combination of using climate model projections and downscaling provides an acceptable baseline for estimating changing climate conditions for the Chesapeake Bay, and the panel finds the CCAF approach to be fundamentally sound. However, the …

Investigating Physical Processes Associated With Chesapeake Bay And Changjiang Estuary, Arash Niroomandi

Civil & Environmental Engineering Theses & Dissertations

Coastal and estuaries are landforms that not only have great impacts on large marine ecosystem, but also play a significant role in moderating or aggravating natural hazards and erosion risks that are expected to increase with climate change. This dissertation explores some of the concerns associated with coasts and coastal systems. In the second chapter, a thirty seven year wave hindcast (1979-2015) in Chesapeake Bay using NCEP's Climate Forecast System Reanalysis (CFSR) wind is presented. The long-term significant wave heights are generated by the third-generation nearshore wave model SWAN, which is validated using the wave height measurements at buoy stations …

Spaceborne Synthetic Aperture Radar Survey Of Subsidence In Hampton Roads, Virginia (Usa), D.P.S. Bekaert, B. D. Hamlington, B. Buzzanga, C. E. Jones

CCPO Publications

Over the past century, the Hampton Roads area of the Chesapeake Bay region has experienced one of the highest rates of relative sea level rise on the Atlantic coast of the United States. This rate of relative sea level rise results from a combination of land subsidence, which has long been known to be present in the region, and rising seas associated with global warming on long timescales and exacerbated by shifts in ocean dynamics on shorter timescales. An understanding of the current-day magnitude of each component is needed to create accurate projections of future relative sea level rise upon …

Twenty-First Century Climate Change And Submerged Aquatic Vegetation In A Temperate Estuary: The Case Of Chesapeake Bay, Thomas M. Arnold, Richard C. Zimmerman, Katharina A.M. Engelhardt, J. Court Stevenson

OES Faculty Publications

Introduction: The Chesapeake Bay was once renowned for expansive meadows of submerged aquatic vegetation (SAV). However, only 10% of the original meadows survive. Future restoration effortswill be complicated by accelerating climate change, including physiological stressors such as a predicted mean temperature increase of 2-6°C and a 50-160% increase in CO2 concentrations.

Outcomes: As the Chesapeake Bay begins to exhibit characteristics of a subtropical estuary, summer heat waves will become more frequent and severe. Warming alone would eventually eliminate eelgrass (Zostera marina) from the region. It will favor native heat-tolerant species such as widgeon grass (Ruppia maritima) while facilitating colonization by …

Total Water Level And Wave Run Up Forecast, Eric Seymour

July 29, 2016: The Latest in Sea Level Rise Science

No abstract provided.

Sea Level Rise In Virginia – Causes, Effects And Response, Tal Ezer, Larry P. Atkinson

Virginia Journal of Science

Sea level rise (SLR) along Virginia’s coasts and around the Chesapeake Bay as measured by tide gauges is analyzed and discussed. It is shown that the SLR rates vary between one location to another and in most locations the rates increase over time (i.e., SLR is accelerating). The latest science of SLR is reviewed and the causes of the high SLR rates in Virginia are discussed. The impacts of land subsidence and ocean currents (changes in the Gulf Stream in particular) on sea level are especially notable and important for predicting future SLR in Virginia. The consequences of SLR on …

A Survey Of Aquatic Organisms For The Cyanotoxin Beta-Methylamino-L-Alanine (Bmaa), Ian M. Sammler

OES Theses and Dissertations

Cyanobacteria blooms are increasing globally as a result of eutrophication. Many cyanobacteria are potentially harmful, not only because of the oxygen depleted zones created when they decay, but also because of the toxins they produce. β- Methylamino-L-alanine (BMAA), reportedly produced by many species of cyanobacteria, is a non-proteinogenic amino acid that has been linked to the development of neurodegenerative diseases (amyotrophic lateral sclerosis (ALS) and Alzheimer's) in humans. This study presents results from an assessment of BMAA in cyanobacteria and their grazers from the lower Chesapeake Bay and Lake Erie regions. BMAA was analyzed in samples prepared with the EZ:Faast™ …

Emergence Of Algal Blooms: The Effects Of Short-Term Variability In Water Quality On Phytoplankton Abundance, Diversity, And Community Composition In A Tidal Estuary, Todd A. Egerton, Ryan E. Morse, Harold G. Marshall, Margaret R. Mulholland

OES Faculty Publications

Algal blooms are dynamic phenomena, often attributed to environmental parameters that vary on short timescales (e.g., hours to days). Phytoplankton monitoring programs are largely designed to examine long-term trends and interannual variability. In order to better understand and evaluate the relationships between water quality variables and the genesis of algal blooms, daily samples were collected over a 34 day period in the eutrophic Lafayette River, a tidal tributary within Chesapeake Bay's estuarine complex, during spring 2006. During this period two distinct algal blooms occurred; the first was a cryptomonad bloom and this was followed by a bloom of the mixotrophic …

Distinguishing Molecular Characteristics Of Aerosol Water Soluble Organic Matter From The 2011 Trans-North Atlantic Us Geotraces Cruise, A. S. Wozniak, A. S. Willoughby, S. C. Gurganus, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The molecular characteristics of aerosol organic matter (OM) determines to a large extent its impacts on the atmospheric radiative budget and ecosystem function in terrestrial and aquatic environments, yet the OM molecular details of aerosols from different sources are not well established. Aerosol particulate samples with North American-influenced, North African-influenced, and marine (minimal recent continental influence) air mass back trajectories were collected as part of the 2011 trans-North Atlantic US GEOTRACES cruise and analyzed for their water soluble OM (WSOM) molecular characteristics using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Principal component analysis (PCA) separated the samples into …

Can We Predict The Future: Juvenile Finfish And Their Seagrass Nurseries In The Chesapeake Bay, Cynthia M. Jones

OES Faculty Publications

The importance of estuarine seagrass beds as nurseries for juvenile fish has become a universal paradigm, especially for estuaries that are as important as the Chesapeake Bay. Yet, scientific tests of this hypothesis were equivocal depending on species, location, and metrics. Moreover, seagrasses themselves are under threat and one-third of seagrasses have disappeared worldwide with 65 of their losses occurring in estuaries. Although there have been extensive studies of seagrasses in the Chesapeake Bay, surprisingly few studies have quantified the relationship between seagrass as nurseries for finfish in the Bay. Of the few studies that have directly evaluated the use …

Circulation, Vol. 18, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Malcolm Scully

CCPO Circulation

Spring 2013 issue of CCPO Circulation featuring article "Physical Modulation of Dissolved Oxygen in Chesapeake Bay" by Dr. Malcolm Scully

Seasonal Dynamics Of Mesodinium Rubrum In Chesapeake Bay, Matthew D. Johnson, Doane K. Stoecker, Harold G. Marshall

Biological Sciences Faculty Publications

The photosynthetic ciliate Mesodinium rubrum is a common member of coastal phytoplankton communities that is well adapted to low-light, turbid ecosystems. It supports the growth of, or competes with, harmful dinoflagellate species for cryptophyte prey, as well as being a trophic link to copepods and larval fish. We have compiled data from various sources (n = 1063), on the abundance and distribution of M. rubrum in Chesapeake Bay and its tributaries. Because M. rubrum relies on obtaining organelles from cryptophyte algae to maintain rapid growth, we also enumerated cryptophyte algae in the portion of these samples that we collected …

A Centennial Record Of Paleosalinity Change In The Tidal Reaches Of The Potomac And Rappahannock Rivers, Tributaries To Chesapeake Bay, Neil E. Tibert, Lindsay J. Walker, William P. Patterson, J. Bradford Hubeny, Emma Jones, Olivia R. Cooper

Virginia Journal of Science

Gravity and push cores from the Potomac and Rappahannock Rivers (Virginia Tidewater) were collected from central and proximal estuarine zones with known seasonal salinity stratification. The lowermost microfossil associations in the cores comprise alternating ostracode populations of Cyprideis salebrosa and Cytheromorpha. This microfossil association gives way to an oligohaline association dominated by the freshwater ostracode Darwinula stevensoni. Stable oxygen isotope values (δ¹⁸O) of Rapphannock Cyprideis salebrosa are highly variable ranging between -6.6 to -3.2‰ VPDB. δ¹⁸O values for Potomac Cytheromorpha fuscata range from -8.2 to -3.2‰ VPDB. Positive excursions in δ¹⁸O values …

Analysis Of Relative Sea Level Variations And Trends In The Chesapeake Bay: Is There Evidence For Acceleration In Sea Level Rise?, Tal Ezer, William B. Corlett

CCPO Publications

Over the past few decades the pace of relative sea level rise (SLR) in the Chesapeake Bay (CB) has been 2-3 times faster than that of the globally mean absolute sea level. Our study is part of ongoing research that tries to determine if this SLR trend is continuing at the same pace, slowing down (SLR deceleration) or speeding up (SLR acceleration). We introduce a new analysis method for sea level data that is based on Empirical Mode Decomposition (EMD) and Hilbert-Huang Transform (HHT); the analysis separates the SLR trend from other oscillating modes of different scales. Bootstrap calculations using …

A Google Earth-Based Framework For Visualization Of The Chesapeake Bay Operational Forecast System, Gary Lawson

Computational Modeling & Simulation Engineering Theses & Dissertations

For the persons who live near and travel the waters of the Chesapeake Bay, the data provided by the Chesapeake Bay Operational Forecast System (CBOFS) is invaluable. The information provided includes measurements and forecasts of surface wind velocity, water current velocity, salinity levels, water level, and temperature. Currently, this information is freely available on the CBQ_FS website hosted by the National Oceanographic and Atmospheric Administration (NOAA). It is offered as Nowcast, measured data, and Forecast data and is visualized using 2D images which describe a subset of the data in an easy to read chart. However, if the data were …

Population Dynamics Of Sheepshead (Archosargus Probatocephalus; Walbaum 1792) In The Chesapeake Bay Region: A Comparison To Other Areas And An Assessment Of Their Current Status, Joseph Charles Ballenger

OES Theses and Dissertations

Sheepshead recently have seen an increase in fishing pressure in Virginian waters of the Chesapeake Bay. This increase in fishing pressure has led to demands to install effective management measures to protect the fishery. However, no study regarding the population dynamics, and thus potential yield, of sheepshead has been conducted north of Cape Hatteras. We addressed the need for information regarding the population dynamics of Chesapeake Bay sheepshead by investigating their age distribution, growth rate and reproductive biology. We used this information to construct yield-per-recruit models, which local management agencies may use in the formation of scientifically based management measures. …

Evaluating Methods For Optimizing Classification Success From Otolith Tracers For Spotted Seatrout (Cynoscion Nebulosus) In The Chesapeake Bay, Stacy Kavita Beharry

OES Theses and Dissertations

Identifying the natal sources of fish is an important step in understanding its population dynamics. Adult recruits are often sourced from multiple nursery areas, with good quality locations contributing disproportionately more fish to the adult stock. Because population persistence is strongly influenced by nursery habitat, methods that correctly identify the source of recruits are necessary for effective management. Within the last decade, otolith chemistry signatures have been increasingly used as a natural marker to delineate fish from a mixture of nursery sources. Despite the widespread use of otolith trace element and stable isotope ratios as habitat markers, the statistical approaches …

Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman

OES Faculty Publications

The diffuse attenuation coefficient Kᵈ is critical to understand the vertical distribution of underwater downwelling irradiance (Eᵈ). Theoretically Eᵈ is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kᵈ is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Eᵈ(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4%. Field …

Phytoplankton Blooms: Their Occurrence And Composition Within Virginia's Tidal Tributaries, Harold G. Marshall, Todd A. Egerton

Virginia Journal of Science

Sporadic algal bloom development within a 10 year monitoring program in Virginia tidal tributaries of Chesapeake Bay is reviewed. These blooms were common events, characteristically producing a color signature to the surface water, typically short lived, occurring mainly from spring into autumn throughout different salinity regions of these rivers, and were produced primarily by dinoflagellates. The abundance threshold levels that would identify bloom status from a non-bloom presence were species specific, varied with the taxon's cell size, and ranged from ca. 10 to 10⁴ cells mL^-1. Among the most consistent sporadic bloom producers were the dinoflagellates Akashiwo …

First Records Of Hypleurochilus Geminatus And Centropristis Philadelphica From Chesapeake Bay, Aimee D. Halvorson

Virginia Journal of Science

During the fall of 2007, Centropris philadelphica (rock seabass) and Hypleurochilus geminatus (Crested blenny) were collected from Chesapeake Bay. These captures are significant as they represent the first substantiated record of C. philadelphica from Chesapeake Bay and only the second and third validated records of H. geminatus. Additionally, the first record of H. geminatus from Chesapeake Bay was only recently recognized since the specimen had been previously misidentified as Parablennius marmoreus (seaweed blenny). The collection of seven individuals of H. geminatus in 2007, from two locations, indicates that the species may be resident within the Chesapeake Bay estuary.

Phytoplankton Blooms: Their Occurence And Composition Within Virginia's Tidal Tributaries, Harold G. Marshall, Todd A. Egerton

Biological Sciences Faculty Publications

Sporadic algal bloom development within a 10 year monitoring program in Virginia tidal tributaries of Chesapeake Bay is reviewed. These blooms were common events, characteristically producing a color signature to the surface water, typically short lived, occurring mainly from spring into autumn throughout different salinity regions of these rivers, and were produced primarily by dinoflagellates. The abundance threshold levels that would identify bloom status from a non-bloom presence were species specific, varied with the taxon's cell size, and ranged from ca. 10 to 10(4) cells mL(-1). Among the most consistent sporadic bloom producers were the dinoflagellates Akashiwo sanguinea, Cochlodinium …