Oceanography and Atmospheric Sciences and Meteorology Commons^™

Iron Geochemistry Across An Estuary-To-Coastal Gradient, Lissett G. Diaz

Honors Theses

Iron is a ubiquitous earth element that participates in biogeochemical processes that occur in marine sediments. Microorganisms utilize iron for many purposes, including cell growth, conserving energy, and for maintaining metabolic activity. In coastal sedimentary settings, understanding the redox reactions involving ferric iron, Fe³⁺, and ferrous iron, Fe²⁺, in its solid phase and pore-water phases, respectively, enable an appreciation of biogeochemical transformations occurring in the coastal zone. In this study, iron concentrations in sediment of ranging permeability were determined at four stations marking an estuary-coast transition zone in Singleton Swash in Myrtle Beach, South Carolina. The …

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 …

Nutrient Cycling In Tropical And Temperate Coastal Waters: Is Latitude Making A Difference?, Christian Lønborg, Moritz Müller, Edward C. V. Butler, Shan Jiang, Seng Keat Ooi, Dieu Huong Trinh, Pui Yee Wong, Suryati M. Ali, Chun Cui, Wee Boon Siong, Erik S. Yando, Daniel A. Friess, Judith A. Rosentreter, Bradley D. Eyre, Patrick Martin

Biological Sciences Faculty Publications

Tropical coastal waters are highly dynamic and amongst the most biogeochemically active zones in the ocean. This review compares nitrogen (N) and phosphorus (P) cycles in temperate and tropical coastal waters. We review the literature to identify major similarities and differences between these two regions, specifically with regards to the impact of environmental factors (temperature, sunlight), riverine inputs, groundwater, lateral fluxes, atmospheric deposition, nitrogen fixation, organic nutrient cycling, primary production, respiration, sedimentary burial, denitrification and anammox. Overall, there are some similarities but also key differences in nutrient cycling, with differences relating mainly to temperature, sunlight, and precipitation amounts and patterns. …

Radiocarbon Analyses Quantify Peat Carbon Losses With Increasing Temperature In A Whole Ecosystem Warming Experiment, Rachel M. Wilson, Natalie A. Griffiths, Ate Visser, Karis J. Mcfarlane, Stephen D. Sebestyen, Keith C. Oleheiser, Samantha Bosman, Anya M. Hopple, Malak M. Tfaily, Randall K. Kolka, Paul J. Hanson, Joel E. Kostka, Scott D. Bridgham, Jason K. Keller, Jeffrey P. Chanton

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Climate warming is expected to accelerate peatland degradation and release rates of carbon dioxide (CO2) and methane (CH4). Spruce and Peatlands Responses Under Changing Environments is an ecosystem-scale climate manipulation experiment, designed to examine peatland ecosystem response to climate forcings. We examined whether heating up to +9 °C to 3 m-deep in a peat bog over a 7-year period led to higher C turnover and CO2 and CH4 emissions, by measuring 14C of solid peat, dissolved organic carbon (DOC), CH4, and dissolved CO2 (DIC). DOC, a major substrate for heterotrophic respiration, increased significantly with warming. There was no 7-year trend …

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 …

Blue Carbon In South Florida's Mangroves: The Role Of Large Roots And Necromass, Zoë I. Shribman

LSU Master's Theses

Blue carbon sequestration and storage in mangroves largely result from belowground biomass allocation in response to flooded anaerobic soil conditions and nutrient availability. Biomass allocation to belowground roots is a major driver of mangrove soil formation and organic matter accumulation leading to blue carbon storage potential. Belowground biomass sampling in mangroves is labor intensive, limiting data availability on biomass stocks, particularly for large roots (>20 mm diameter) and necromass (dead roots). The mangrove nutrient model (NUMAN) uses mostly literature values to parameterize a soil cohort approach to simulate depth distribution of root mass and organic carbon concentration. We evaluated …

Carbon And Nitrogen Dynamics Of A Lagoon Salt Marsh In Davenport, California, Mark D. Gormley

Dissertations, Theses, and Capstone Projects

Wetlands are complex environments that play a critical role in regulating the global biogeochemical cycle of carbon (C) and nitrogen (N). Wetlands are critical contributors to global climate change and atmospheric chemistry since they store as much as 33% of the world’s soil organic carbon (SOC), release more than 20% of the atmospheric methane (CH₄), and produce nitrous oxide (N₂O), an extremely potent greenhouse gas (GHG). Despite the enormous radiative forcing potential of carbon dioxide (CO₂), CH₄ and N₂O derived from wetlands, uncertainties over the rates of C sequestration and GHG …

The Variability Of Seawater Carbonate Chemistry In Two Florida Urban Mangrove Ecosystems, Alexandrina R. Rangel

All HCAS Student Capstones, Theses, and Dissertations

Anthropogenic carbon dioxide (CO₂) emissions into the atmosphere are yielding serious impacts across the world’s ocean, including ocean acidification, sea level rise, and increasing seawater temperature. However, these changes are not occurring uniformly across all marine ecosystems. Coastal ecosystems, such as mangroves, already experience extreme and variable environmental conditions due to natural biogeochemical and physical processes. The goal of this study was to document small-scale variability in two urban mangrove ecosystems to gain insight into how ocean acidification will manifest within these systems. Using a stand-up paddleboard, a suite of sensors, and traditional bottle sampling techniques, we measured …

Phragmites Australis Dieback In The Mississippi River Delta: Chemical Profiles Of Soil Types And Restoration Potential, Herie Lee

LSU Master's Theses

Since 2016, there has been widespread dieback of P. australis in the Lower Mississippi River Delta (hereafter referred to as Lower MRD, which is defined as the Birds Foot Delta) with relatively little to no signs of recovery. The cause of the current dieback is not fully understood. This thesis explores P. australis with emphasis on chemical profile characterization of different soil types and its effects on plant growth and the potential for restoration in the Lower MRD.

In chapter 2, I characterized the chemical profiles of soils collected from healthy and dieback stands of Phragmites, and from newly …

An Integrative Model For Soil Biogeochemistry And Methane Processes: I. Model Structure And Sensitivity Analysis, Daniel M. Ricciuto, Xiaofeng Xu, Xiaoying Shi, Yihui Wang, Xia Song, Christopher W. Schadt, Natalie A. Griffiths, Jiafu Mao, Jeffrey M. Warren, Peter E. Thornton, Jeff Chanton, Jason K. Keller, Scott D. Bridgham, Jessica Gutknecht, Stephen D. Sebestyen, Adrien Finzi, Randall Kolka, Paul J. Hanson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Environmental changes are anticipated to generate substantial impacts on carbon cycling in peatlands, affecting terrestrial-climate feedbacks. Understanding how peatland methane (CH₄) fluxes respond to these changing environments is critical for predicting the magnitude of feedbacks from peatlands to global climate change. To improve predictions of CH₄ fluxes in response to changes such as elevated atmospheric CO₂ concentrations and warming, it is essential for Earth system models to include increased realism to simulate CH₄ processes in a more mechanistic way. To address this need, we incorporated a new microbial-functional group-based CH₄ module into the Energy …

Linking Human Activities To Water Quality In Coastal New England: Past And Present, Amelia Hurst

University Scholar Projects

This project examines the timing and effect of direct and indirect anthropogenic and natural influences on the marine environment in embayments in southern New England over the past decades to century timescale. We investigated the effects of human land use from colonial through post-industrial times, determined baseline conditions and natural climatic variability, and analyzed the response of marine ecosystems to specific local management actions aimed to improve water quality. A coastal sediment core was taken in Mumford Cove, CT and was analyzed downcore for eutrophication markers (C: N, %C, %N, d¹⁵N, d¹³C) and metals (Hg, Pb, …

Microplankton Dynamics In The River-Dominated Mississippi Bight, Adam D. Boyette

Dissertations

The Mississippi Bight (MSB) is a river-dominated continental margin influenced by multiple large river systems, including the Mississippi River, Alabama and Tombigbee rivers via Mobile Bay, and numerous smaller rivers, creeks, and bayous. This is part of a biologically-rich ecosystem that supports the second largest fishery industry by volume in the United States. Despite our understanding of the linkages between primary production with higher trophic levels, there remains limited studies quantifying these trophic interactions in this system. Microplankton (µm) community dynamics and trophic connectivity between primary producers and heterotrophic protists represent a critical nexus influencing overall biological productivity in this …

Isolated Point Discharges Into Coastal Swashes As Nutrient Sources To Coastal Waters, Mary E. Olsen

Honors Theses

Coastal water quality in the Grand Strand of South Carolina is directly influenced by human activities. Nutrient-rich runoff, stemming from numerous anthropogenic sources, finds its way into coastal waters through freshwater inputs often through tidal creeks, termed swashes. In order to better describe the amount of nutrient inputs into Singleton Swash and White Point Swash, we examine anthropogenic runoff from isolated identifiable point discharges and their nutrient concentrations. We report concentrations of dissolved inorganic nitrogen (DIN, as the sum of nitrate, nitrite and ammonium) and phosphate in discharge and creek water. We hypothesize that nutrient concentrations of isolated, minor point …

Organic Matter Spatial And Temporal Patterns In Coastal Sands Of Long Bay, South Carolina, Kayla B. Christofferson

Honors Theses

Sandy coastlines serve crucial functions to coastal economies and coastal ecology alike. In the past, organic-poor sands were considered of lower importance than organic-rich muds. Recent studies showed that sands’ low organic matter concentrations are due to high biogeochemical cycling rates, driven by rapid physical exchange, but remain infrequently studied. I present time-series of sand mass-loss-on-ignition (LOI, an organic matter proxy) profiles from February 2017 onwards at multiple sites along Long Bay, South Carolina. LOI profiles exhibit subsurface maximum values, unlike the typical decrease with depth in muddy sediments. I hypothesize that organic matter distribution with depth is affected by …

Alexandrium In The Arctic: Are Harmful Algae Spreading As The Arctic Warms?, Sveinn Einarsson, Kate Lowry, Robert Pickart, Karin Ashjian, P. Dreux Chappell

College of Sciences Posters

Alexandrium tamerense is a well-studied dinoflagellate known for its ability to produce the neurotoxin that causes paralytic shellfish poisoning. Until 1970 Alexandrium tamerense was only found in Europe, North America, and Japan but has been increasingly found all over the globe. Alexandrium is characteristically found in temperate and subtropical regions and as the Arctic warms, there is considerable concern that it may be expanding into the Arctic. We found Alexandrium tamerense during a research expedition to the Alaskan Beaufort Sea shelf to study upwelling. Upwelling events are known to support seasonal blooms of phytoplankton, which are important primary producers at …

Defining The Environmental Niche Of The Two Main Clades Of Trichodesmium: A Study On The West Florida Shelf, Kristina Confesor, Corday Selden, Kimberly Powell, Angela Knapp, Kristen Buck, Laura Donahue, Dreux Chappell

College of Sciences Posters

Dinitrogen (N₂) fixation is the process of taking widely abundant but mostly biologically inaccessible N₂ gas and converting it into more biologically accessible forms of the essential macronutrient nitrogen. Only a small fraction of organisms known as diazotrophs can perform biological N₂ fixation. Trichodesmium is one such genus of N₂-fixing marine cyanobacteria that is commonly observed in waters along the West Florida Shelf (WFS). We hypothesize that the two main Trichodesmium clades (T. erythraeum and T. thiebautii) occupy distinct environmental niches, one being more coastal and one being more oceanic. To test …

Seasonal Variability In Diazotroph Abundance And Gene Expression At A Coastal N2 Fixation Hotspot (Outer Banks, Nc), Katherine Crider, Corday Selden, Kimberly Powell, P. Dreux Chappell

College of Sciences Posters

Marine microbial dinitrogen (N₂) fixation, the conversion of gaseous N₂ to bioavailable species, is the primary source of new oceanic nitrogen (N). N is present in nucleic acids, amino acids, and proteins, and is essential to all life. Long considered to be a primarily oligotrophic ocean process, significant N₂ fixation rates have recently been observed in coastal environments, including along the Cape Hatteras front. To see if elevated N₂ fixation was a persistent feature in this region, N₂ fixation rates and N₂ fixer (diazotroph) abundance and gene expression were investigated through roughly monthly …

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

FIU Electronic Theses and Dissertations

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

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

Multi-Source Eo For Dynamic Wetland Mapping And Monitoring In The Great Lakes Basin, Michael Battaglia, Sarah Banks, Amir Behnamian, Laura Bourgeau-Chavez

Michigan Tech Publications

Wetland managers, citizens and government leaders are observing rapid changes in coastal wetlands and associated habitats around the Great Lakes Basin due to human activity and climate variability. SAR and optical satellite sensors offer cost effective management tools that can be used to monitor wetlands over time, covering large areas like the Great Lakes and providing information to those making management and policy decisions. In this paper we describe ongoing efforts to monitor dynamic changes in wetland vegetation, surface water extent, and water level change. Included are assessments of simulated Radarsat Constellation Mission data to determine feasibility of continued monitoring …

Estuaries As Filters For Riverine Microplastics: Simulations In A Large, Coastal-Plain Estuary, Alexander G. Lopez, Raymond G. Najjar, Marjorie A.M. Friedrichs, Michael A. Hickner, Denice H. Wardrop

VIMS Articles

Public awareness of microplastics and their widespread presence throughout most bodies of water are increasingly documented. The accumulation of microplastics in the ocean, however, appears to be far less than their riverine inputs, suggesting that there is a “missing sink” of plastics in the ocean. Estuaries have long been recognized as filters for riverine material in marine biogeochemical budgets. Here we use a model of estuarine microplastic transport to test the hypothesis that the Chesapeake Bay, a large coastal-plain estuary in eastern North America, is a potentially large filter, or “sink,” of riverine microplastics. The 1-year composite simulation, which tracks …

Effects Of Tidal Flooding On Estuarine Biogeochemistry: Quantifying Flood-Driven Nitrogen Inputs In An Urban, Lower Chesapeake Bay Sub-Tributary, Alfonso Macías-Tapia, Margaret R. Mulholland, Corday R. Selden, J. Derek Loftis, Peter W. Bernhardt

OES Faculty Publications

Sea level rise has increased the frequency of tidal flooding even without accompanying precipitation in many coastal areas worldwide. As the tide rises, inundates the landscape, and then recedes, it can transport organic and inorganic matter between terrestrial systems and adjacent aquatic environments. However, the chemical and biological effects of tidal flooding on urban estuarine systems remain poorly constrained. Here, we provide the first extensive quantification of floodwater nutrient concentrations during a tidal flooding event and estimate the nitrogen (N) loading to the Lafayette River, an urban tidal sub-tributary of the lower Chesapeake Bay (USA). To enable the scale of …

Bioactive Trace Metals And Their Isotopes As Paleoproductivity Proxies: An Assessment Using Geotraces-Era Data, T. J. Horner, S. H. Little, T. W. Conway, J. R. Farmer, Jennifer E. Hertzberg, D. J. Janssen, A.J.M. Lough, J.L. Mckay, A. Tessin, S.J.G. Galer, S. L. Jaccard, F. Lacan, A. Paytan, K. Wuttig, Geotraces-Pages Biological Productivity Working Group Members

OES Faculty Publications

Phytoplankton productivity and export sequester climatically significant quantities of atmospheric carbon dioxide as particulate organic carbon through a suite of processes termed the biological pump. Constraining how the biological pump operated in the past is important for understanding past atmospheric carbon dioxide concentrations and Earth's climate history. However, reconstructing the history of the biological pump requires proxies. Due to their intimate association with biological processes, several bioactive trace metals and their isotopes are potential proxies for past phytoplankton productivity, including iron, zinc, copper, cadmium, molybdenum, barium, nickel, chromium, and silver. Here, we review the oceanic distributions, driving processes, and depositional …

Neodymium Isotope Geochemistry Of A Subterranean Estuary, Darren A. Chevis, T. Jade Mohajerin, Ningfang Yang, Jaye E. Cable, E. Troy Rasbury, Sidney R. Hemming, David J. Burdige, Jonathan B. Martin, Christopher D. White, Karen H. Johannesson

OES Faculty Publications

Rare earth elements (REE) and Nd isotope compositions of surface and groundwaters from the Indian River Lagoon in Florida were measured to investigate the influence of submarine groundwater discharge (SGD) on these parameters in coastal waters. The Nd flux of the terrestrial component of SGD is around 0.7 ± 0.03 μmol Nd/day per m of shoreline across the nearshore seepage face of the subterranean estuary. This translates to a terrestrial SGD Nd flux of 4 ± 0.2 mmol/day for the entire 5,880 m long shoreline of the studied portion of the lagoon. The Nd flux from bioirrigation across the nearshore …

The Quantitative Assessment Of Pond Scum: An Examination Of The Biogeochemistry Of Phosphorus Cycling In The Belgrade Lakes, Abbey M. Sykes

Honors Theses

The internal recycling phosphorus in freshwater lake bottom sediments represents a significant source of hypolimnetic phosphorus (P) release for many of Maine’s lakes. In summer months, Maine lakes often thermally stratify and the lake hypolimnion develops anoxia, leading to a reduction in redox potential at the sediment-water interface. These reducing conditions facilitate the reductive dissolution of ferric iron, and, since phosphorus is often present in freshwater lake sediments as solid FeOOH-PO₄ complexes, results in release of soluble phosphorus into the water column. Our current study presents field and laboratory data from sediment fractionation extractions designed to quantify concentrations of …

Taxonomic And Nutrient Controls On Phytoplankton Iron Quotas In The Ocean, Benjamin S. Twining, Olga Antipova, P. Dreux Chappell, Natalie R. Cohen, Jeremy E. Jacquot, Elizabeth L. Mann, Adrian Marchetti, Daniel C. Ohnemus, Sara Rauschenberg, Alessandro Tagliabue

OES Faculty Publications

Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of …