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Articles 31 - 60 of 208
Full-Text Articles in Oceanography
Nitrogen Cycling In The Lower Chesapeake Bay And Mid- And South Atlantic Bight, Yifan Zhu
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. …
The Dynamics Of Sedimentary Chlorophyll Α At A High-Energy Beach, Sarah (Gray) Abel
The Dynamics Of Sedimentary Chlorophyll Α At A High-Energy Beach, Sarah (Gray) Abel
Honors Theses
Productive sandy beaches are one of the most crucial areas serving our ecosystem today. While often overlooked in scientific research, productive beaches have many essential functions that lead to the preservation and protection of many different species as well as ecological wellness and stability. A key factor that is linked to this productivity is the presence of chlorophyll in the sediments. Piston cores of the sediments at the low-tide mark at Waties Island, South Carolina, were collected across multiple years and subsequently analyzed for chlorophyll concentrations through fluorometry after acetone extraction and acidification. Each core profile was processed to calculate …
Investigation Of A Possible Switch Of Benthic Photosynthetic Organisms And Phytoplanktonic Organisms In White Point Swash, South Carolina, Nathan Easterling
Investigation Of A Possible Switch Of Benthic Photosynthetic Organisms And Phytoplanktonic Organisms In White Point Swash, South Carolina, Nathan Easterling
Honors Theses
This research study examined the possible switch from benthic photosynthetic organisms to phytoplankton in the water column at White Point Swash, Long Bay, South Carolina, and what is causing this switch to occur. During Dr. Hannides’ and his group’s studies at this and other swashes in the past, they noticed this phenomenon of the benthic photosynthetic organisms taking over during a certain time and then the phytoplankton in the water column taking over during a different time. In this study, I measured the relative benthic macroalgal area coverage and sedimentary chlorophyll a concentration as measures of the abundance of benthic …
Suboxic And Anaerobic Respiration Across A Sandy-Shore-To-Estuarine Gradient, Jacey Ballard
Suboxic And Anaerobic Respiration Across A Sandy-Shore-To-Estuarine Gradient, Jacey Ballard
Honors Theses
Sulfate is an inorganic ion that is one of the major ions of seawater. Sulfate is also an essential reactant in microbially mediated anaerobic respiration that produces sulfide, an energy source during chemosynthesis. Sulfide is widely found in sediment, and water rich in decaying organic material, as well as hydrothermal vents. While sulfate reduction occurs extensively in muds, such as those of marshes, it is not expected to occur in sand which is much better aerated. Recent research in our group documented extensive sub aerobic respiration in coastal sands which suggests that sulfate reduction may have also been happening. This …
Dust Deposition To The Bermuda Region: A Comparison Of Estimates Using Seasonally-Resolved Measurements Of Aluminum In Water-Column, Aerosol, And Rain Samples, Tara Williams, Peter Sedwick, Bettina Sohst, Joe Resing, Kristen Buck, Salvatore Caprara, Rod Johnson, Dan Ohnemus, Ben Twining, Alessandro Tagliabue
Dust Deposition To The Bermuda Region: A Comparison Of Estimates Using Seasonally-Resolved Measurements Of Aluminum In Water-Column, Aerosol, And Rain Samples, Tara Williams, Peter Sedwick, Bettina Sohst, Joe Resing, Kristen Buck, Salvatore Caprara, Rod Johnson, Dan Ohnemus, Ben Twining, Alessandro Tagliabue
College of Sciences Posters
Dust deposition is a major source of bioactive trace elements to the surface ocean, yet this flux remains difficult to constrain. Previously, time-averaged dust flux has been estimated using surface ocean dissolved aluminum (DAl) concentrations, assumed values for aerosol aluminum solubility (%AlS), and the residence time of DAl in the surface mixed layer (SML). We apply this method to estimate dust deposition in the Bermuda Atlantic Time-series Study (BATS) region using water-column DAl data from cruises in 2019, which is compared with direct flux estimates from contemporaneous measurements of aluminum in aerosols and rain collected on Bermuda. Seasonal …
Interactions Of Bioactive Trace Metals In Shipboard Southern Ocean Incubation Experiments, Shannon M. Burns, Randelle M. Bundy, William Abbott, Zuzanna Abdala, Alexa R. Sterling, P. Dreux Chappell, Bethany D. Jenkins, Kristen N. Buck
Interactions Of Bioactive Trace Metals In Shipboard Southern Ocean Incubation Experiments, Shannon M. Burns, Randelle M. Bundy, William Abbott, Zuzanna Abdala, Alexa R. Sterling, P. Dreux Chappell, Bethany D. Jenkins, Kristen N. Buck
OES Faculty Publications
In the Southern Ocean, it is well‐known that iron (Fe) limits phytoplankton growth. Yet, other trace metals can also affect phytoplankton physiology. This study investigated feedbacks between phytoplankton growth and dissolved Fe, manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in Southern Ocean shipboard incubations. Three experiments were conducted in September–October 2016 near the West Antarctic Peninsula: Incubations 1 and 3 offshore in the Antarctic Circumpolar Current, and Incubation 2 inshore in Bransfield Strait. Additions of Fe and/or vitamin B12 to inshore and offshore waters were employed and allowed assessment of metal (M) …
Carbonate Chemistry And Carbon Sequestation Driven By Inorganic Carbon Outwelling From Mangroves And Saltmarshes, Gloria M. S. Reithmaier, Alex Cabral, Anirban Akhand, Matthew J. Bogard, Alberto V. Borges, Steven Bouillon, David J. Burdige, Mitchell Call, Nengwang Chen, Xiaogang Chen, Luiz C. Cotovicz Jr., Meagan J. Eagle, Erik Kristensen, Kevin D. Kroeger, Zeyang Lu, Damien T. Maher, J. Lucas Pérez-Lloréns, Raghab Ray, Pierre Taillardat, Joseph J. Tamborski, Rob C. Upstill-Goddard, Faming Wang, Zhaohui Aleck Wang, Kai Xiao, Yvonne Y.Y. Yau, Isaac R. Santos
Carbonate Chemistry And Carbon Sequestation Driven By Inorganic Carbon Outwelling From Mangroves And Saltmarshes, Gloria M. S. Reithmaier, Alex Cabral, Anirban Akhand, Matthew J. Bogard, Alberto V. Borges, Steven Bouillon, David J. Burdige, Mitchell Call, Nengwang Chen, Xiaogang Chen, Luiz C. Cotovicz Jr., Meagan J. Eagle, Erik Kristensen, Kevin D. Kroeger, Zeyang Lu, Damien T. Maher, J. Lucas Pérez-Lloréns, Raghab Ray, Pierre Taillardat, Joseph J. Tamborski, Rob C. Upstill-Goddard, Faming Wang, Zhaohui Aleck Wang, Kai Xiao, Yvonne Y.Y. Yau, Isaac R. Santos
OES Faculty Publications
Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that >70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing the pH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m−2 …
Epiphytic Diatom Production On The Seagrass Thalassia Testudinum In Northern Gulf Of Mexico, Jonathan L. Venable, Shayna A. Sura, Jeffrey W. Krause
Epiphytic Diatom Production On The Seagrass Thalassia Testudinum In Northern Gulf Of Mexico, Jonathan L. Venable, Shayna A. Sura, Jeffrey W. Krause
Gulf and Caribbean Research
No abstract provided.
Larval Ecology Of Atlantic Bluefin Tuna (Thunnus Thynnus): New Insights From Otolith Microstructure, Biotic, And Abiotic Analyses From The Gulf Of Mexico And Mediterranean Sea, Estrella Malca
All HCAS Student Capstones, Theses, and Dissertations
Atlantic bluefin tuna (ABT), Thunnus thynnus, spawn in the Gulf of Mexico (GoM) and the Mediterranean Sea (MED). Spawning occurs within narrow temporal and environmental parameters. Efforts to characterize growth of ABT in wild conditions revealed a wide range of growth variability during the early life stages. This series of studies examined potential biotic and abiotic influences of larval growth from seven ABT cohorts, and identified several key drivers of growth for this commercially valuable species. A detailed investigation of larval dynamics using otolith microstructure was conducted as follows. First, companion growth curves and stable isotope analysis from the same …
Evaluating The Impact Of Submarine Groundwater Discharge On Nutrients And Trace Elements In Coastal Systems: The Examples Of The Tuckean Swamp (Australia) And The Mississippi Sound (Usa), Amy Moody
Dissertations
Submarine groundwater discharge (SGD) is the advective flow of both fresh terrestrial groundwater and recirculating seawater through aquifer sediments, which is released into the coastal ocean. In this dissertation, I evaluated the impact of SGD on the distributions and input of trace metals and nutrients. In the Tuckean Swamp, an estuary in Australia dominated by coastal acid sulfate soils, I determined the impact of groundwater on Ba and U during the flood season, when the local aquifer is flushed out after a rapid increase in water table elevation. For Ba and U, groundwater contributed up to 18 and 66 % …
Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot
Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot
LSU Master's Theses
Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …
Understanding Biogeochemical And Physical Controls On Methane Air-Sea Exchange Fluxes In The Pacific Ocean, Sarah Raney
Understanding Biogeochemical And Physical Controls On Methane Air-Sea Exchange Fluxes In The Pacific Ocean, Sarah Raney
Master's Theses
Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH4 m-2 d-1. Average CH4 flux along the Alaskan margin was 2.2 ± 2.9 µmol CH4 m-2 d-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near …
Controls On Buffering And Coastal Acidification In A Temperate Estuary, Christopher W. Hunt, Joseph Salisbury, Douglas Vandemark
Controls On Buffering And Coastal Acidification In A Temperate Estuary, Christopher W. Hunt, Joseph Salisbury, Douglas Vandemark
Faculty Publications
Estuaries may be uniquely susceptible to the combined acidification pressures of atmospherically driven ocean acidification (OA), biologically driven CO2 inputs from the estuary itself, and terrestrially derived freshwater inputs. This study utilized continuous measurements of total alkalinity (TA) and the partial pressure of carbon dioxide (pCO2) from the mouth of Great Bay, a temperate northeastern U.S. estuary, to examine the potential influences of endmember mixing and biogeochemical transformation upon estuary buffering capacity (β–H). Observations were collected hourly over 28 months representing all seasons between May 2016 and December 2019. Results indicated that endmember mixing explained most of the observed variability …
Editorial: Carbon Cycling In Aquatic Critical Zones, Peng Yao, Thomas S. Bianchi, David J. Burdige, Xiaojuan Feng, Peter A. Raymond
Editorial: Carbon Cycling In Aquatic Critical Zones, Peng Yao, Thomas S. Bianchi, David J. Burdige, Xiaojuan Feng, Peter A. Raymond
OES Faculty Publications
No abstract provided.
Validation Of The Use Of Clathromorphum Compactum Growth And Skeletal Δ18o As A Proxy For Seawater Conditions, Teagan Mcmahon
Validation Of The Use Of Clathromorphum Compactum Growth And Skeletal Δ18o As A Proxy For Seawater Conditions, Teagan Mcmahon
Pitzer Senior Theses
Crustose coralline algae (CCA) are important organisms that create benthic habitat in the photic zone of oceans worldwide. CCAs mechanisms of photosynthesis and calcification may, in some cases, make them vulnerable to climate change and ocean acidification. Therefore, CCA are important not only for their ecological role within ecosystems but also for their ability to indicate the effects that ocean acidification and climate change may have on other marine calcifying organisms. Some species of CCA are known to be useful recorders of paleo oceanic conditions. These climate archives and reconstructions of past environmental conditions are important for understanding past changes …
Iron Geochemistry Across An Estuary-To-Coastal Gradient, Lissett G. Diaz
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 …
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
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. …
Blue Carbon In South Florida's Mangroves: The Role Of Large Roots And Necromass, Zoë I. Shribman
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 …
Organic Matter Spatial And Temporal Patterns In Coastal Sands Of Long Bay, South Carolina, Kayla B. Christofferson
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 …
Isolated Point Discharges Into Coastal Swashes As Nutrient Sources To Coastal Waters, Mary E. Olsen
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 …
Microplankton Dynamics In The River-Dominated Mississippi Bight, Adam D. Boyette
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 …
Alexandrium In The Arctic: Are Harmful Algae Spreading As The Arctic Warms?, Sveinn Einarsson, Kate Lowry, Robert Pickart, Karin Ashjian, P. Dreux Chappell
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 …
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
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 …
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
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 …
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
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 …
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
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 …
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
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 …
In The Margins: Reconsidering The Range And Contribution Of Diazotrophs In Nearshore Environments, Corday R. Selden
In The Margins: Reconsidering The Range And Contribution Of Diazotrophs In Nearshore Environments, Corday R. Selden
OES Theses and Dissertations
Dinitrogen (N2) fixation enables primary production and, consequently, carbon dioxide drawdown in nitrogen (N) limited marine systems, exerting a powerful influence over the coupled carbon and N cycles. Our understanding of the environmental factors regulating its distribution and magnitude are largely based on the range and sensitivity of one genus, Trichodesmium. However, recent work suggests that the niche preferences of distinct diazotrophic (N2 fixing) clades differ due to their metabolic and ecological diversity, hampering efforts to close the N budget and model N2 fixation accurately. Here, I explore the range of N2 fixation …
Monitoring 2019 Bonnet Carré Spillway Impacts - Final Report, J. Read Hendon, Jerry D. Wiggert, Jill Hendon
Monitoring 2019 Bonnet Carré Spillway Impacts - Final Report, J. Read Hendon, Jerry D. Wiggert, Jill Hendon
Faculty Publications
Due to the multiple and extended openings of the Bonnet Carré Spillway in 2019, the University of Southern Mississippi (USM) was tasked by the Mississippi Department of Marine Resources to conduct ecological sampling in the Mississippi Sound and adjacent waters. in an effort to better understand the impacts of the extensive freshwater diversion of Bonnet Carré Spillway operations on Mississippi's coastal and marine resources. The period of performance for this project was June 1, 2019, to August 31, 2019. This technical report summarizes the three months of weekly surveys and analyses, over June - August 2019, conducted by the University …
Potential Virus-Mediated Nitrogen Cycling In Oxygen-Depleted Oceanic Waters, M. Consuelo Gazitúa, Dean R. Vik, Simon Roux, Ann C. Gregory, Benjamin Bolduc, Brittany Widner, Margaret R. Mulholland, Steven J. Hallam, Osvaldo Ulloa, Matthew B. Sullivan
Potential Virus-Mediated Nitrogen Cycling In Oxygen-Depleted Oceanic Waters, M. Consuelo Gazitúa, Dean R. Vik, Simon Roux, Ann C. Gregory, Benjamin Bolduc, Brittany Widner, Margaret R. Mulholland, Steven J. Hallam, Osvaldo Ulloa, Matthew B. Sullivan
OES Faculty Publications
Viruses play an important role in the ecology and biogeochemistry of marine ecosystems. Beyond mortality and gene transfer, viruses can reprogram microbial metabolism during infection by expressing auxiliary metabolic genes (AMGs) involved in photosynthesis, central carbon metabolism, and nutrient cycling. While previous studies have focused on AMG diversity in the sunlit and dark ocean, less is known about the role of viruses in shaping metabolic networks along redox gradients associated with marine oxygen minimum zones (OMZs). Here, we analyzed relatively quantitative viral metagenomic datasets that profiled the oxygen gradient across Eastern Tropical South Pacific (ETSP) OMZ waters, assessing whether OMZ …