Oceanography Commons^™

Characterizing The Unique Chemical Imprint Of On-Axis, Lower-Temperature Hydrothermal Flow To The Deep Ocean (Southern East Pacific Rise, 16.5°–18.0°S), Laura E. Moore, Randelle M. Bundy, Joseph A. Resing, Scott M. White, Tamara Baumberger, Peter N. Sedwick, Nathaniel J. Buck, Anson M. Antriasian, Isaac Keohane

Faculty Publications

In addition to high-temperature vents, lower-temperature flow (LTF) (< 300°C) is abundant along mid-ocean ridges and contributes globally-important fluxes of heat and water along with largely-unconstrained geochemical influences on the ocean. We examined the impact of on-axis LTF on the chemical composition of the overlying water column (< 40 m above seafloor) along the 16.5°–18.0°S sector of the ultrafast-spreading southern East Pacific Rise using autonomous underwater vehicle Sentry surveys and conductivity-temperature-depth rosette casts. LTF sites were typically spatially isolated from high-temperature systems and imparted unique chemical signatures to the overlying ocean. Water column samples impacted by LTF exhibited low particulate iron:sulfur ratios and high methane: total-dissolvable manganese ratios, whereas samples influenced by high-temperature venting exhibited opposite trends. We confirmed that LTF imparts a distinct and measurable chemical signature to the water column, independent from high-temperature vents. Isolated, on-axis LTF will be important to consider when assessing hydrothermal circulation impacts upon ocean biogeochemistry.

Bgc-Argo Float Reveals Shifts In Nitrogen-Carbon Cycling In An Oxygen-Deficient Zone, Mariana B. Bif, Colette Kelly, Mark A. Altabet, Annie Bourbonnais, Claire Elbon, Edgart Flores, Alanna Mnich, Josh Plant, Kenneth S. Johnson

Faculty Publications

Oxygen-deficient zones are hotspots of marine fixed nitrogen loss, but the temporal dynamics of their microbial processes remain poorly resolved. Here we present a nearly three-year high-resolution record from a Biogeochemical Argo float in the Eastern Tropical North Pacific that captures a decline in nitrite concentrations, reflecting a shift in nitrogen redox balance. Using a stoichiometric mass-balance model, we quantify nitrogen transformations, including dissimilatory nitrate reduction to nitrite, denitrification, anammox, and nitrite oxidation, and their coupling to carbonate chemistry. The model shows that dissimilatory nitrate reduction to nitrite dominates nitrogen transformations, while denitrification and anammox vary over depth, biogeochemical transition, …

Ecology And Life History Of Baleen Whales Inform Climate Change Vulnerabilities And Priorities For Future Monitoring, Lesley H. Thorne, Erin L. Meyer-Gutbrod

Faculty Publications

Baleen whales are key consumers in marine habitats that serve as vectors of nutrients, but their populations have been slow to recover from past commercial whaling due to their low reproductive rates and ongoing anthropogenic threats. Climate impacts have become central to the demography and habitat use of baleen whales, and conservation efforts must account for these impacts to be effective. However, knowledge of baleen whale climate responses is lacking, and current survey effort is insufficient to capture changes in migration and habitat use for many species. Due to their unique combination of ecological and life history characteristics, baleen whales …

Understanding The 2016–2018 Freshening Dynamics Of The Beaufort Gyre Through Observations And Model Reanalysis, Christina Gregory, Ganesh Gopalakrishnan, Bulusu Subrahmanyam

Faculty Publications

The Beaufort Gyre (BG) in the Arctic Ocean has experienced rapid changes in losing extensive amounts of sea-ice and undergoing freshening over the past few decades. In this study, we highlight important recent changes in BG’s surface circulation, and its impact on freshwater (FW) fluxes and freshwater content (FWC) and draw attention to the critical importance of continuous monitoring of BG dynamics. Using satellite observations of the upper ocean state and ocean and atmospheric reanalysis, here we attempt to understand the anomalous behavior of BG dynamics over the past few decades. In recent years, atmospheric forcings increasingly influenced important judications …

Streams Guidelines: Standards For Technical Reporting In Environmental And Host-Associated Microbiome Studies, Julia M. Kelliher, Chloe Mirzayi, Sarah R. Bordenstein, Aaron Oliver, Christina A. Kellogg, Eneida L. Hatcher, Maureen Berg, Petr Baldrian, Mashael Aljumaah, Cassandra Maria Luz Miller, Christopher Mungall, Vlastimil Novak, Alexis Palucki, Ethan Smith, Nazifa Tabassum, Gregory Bonito, J. Rodney Brister, Patrick S. Chain, Mingfei Chen, Samuel Degregori, Xuefeng Peng, Et. Al.

Faculty Publications

The interdisciplinary nature of microbiome research, coupled with the generation of complex multi-omics data, makes knowledge sharing challenging. The Strengthening the Organization and Reporting of Microbiome Studies (STORMS) guidelines provide a checklist for the reporting of study information, experimental design and analytical methods within a scientific manuscript on human microbiome research. Here, in this Consensus Statement, we present the standards for technical reporting in environmental and host-associated microbiome studies (STREAMS) guidelines. The guidelines expand on STORMS and include 67 items to support the reporting and review of environmental (for example, terrestrial, aquatic, atmospheric and engineered), synthetic and non-human host-associated microbiome …

Flow Structure And Mixing Near A Small River Plume Front: Winyah Bay, Sc, Usa, Christopher Papageorgiou, George Voulgaris, Alexander E. Yankovsky, Diane Bennett Fribance

Faculty Publications

This study presents Eulerian data from Winyah Bay, SC, USA collected during the passage of a tidal plume. The data captured the evolution and structure of the plume and include high-resolution velocity and temperature time series, supplemented by temperature – salinity profiles from a MicroCTD profiler. The observations identified a pre-existing plume extending to 4 m, with a water density of 1023.6 kg m⁻³, laying above denser ambient waters. Upon arrival, the newly discharged tidal plume introduced a fresher layer (1020.7 kg m⁻³) extending to 2.6 m, gradually thinning due to radial spreading. The plume's frontal …

Flow Structure And Mixing Near A Small River Plume Front: Winyah Bay, Sc, Usa, Christopher Papageorgiou, George Voulgaris, Alexander E. Yankovsky, Diane Bennett Fribance

Faculty Publications

This study presents Eulerian data from Winyah Bay, SC, USA collected during the passage of a tidal plume. The data captured the evolution and structure of the plume and include high-resolution velocity and temperature time series, supplemented by temperature – salinity profiles from a MicroCTD profiler. The observations identified a pre-existing plume extending to 4 m, with a water density of 1023.6 kg m⁻³, laying above denser ambient waters. Upon arrival, the newly discharged tidal plume introduced a fresher layer (1020.7 kg m⁻³) extending to 2.6 m, gradually thinning due to radial spreading. The plume's frontal …

Interactions And Community Structure Of Fungi And Prokaryotes In Salt And Brackish Marsh Ecosystems, Madeleine A. Thompso, Xuefeng Peng

Faculty Publications

Microbial communities play a fundamental role in biogeochemical cycling within salt and brackish marsh ecosystems, yet fungal-prokaryotic interactions in these environments remain poorly understood. This study employed metabarcoding of the 16S and 28S rRNA genes to investigate prokaryotic and fungal communities across four locations in sediments and surface waters of the North Inlet salt marsh and Winyah Bay brackish marsh (South Carolina, USA) over four time points from 2020 to 2021. Co-occurrence network analyses were used to identify potential microbial interactions and their ecological implications. Distinct fungal and prokaryotic communities were observed between the two marsh types. From the 16S …

Decreasing Foraminiferal Flux In Response To Ongoing Climate Change In The Santa Barbara Basin, California, Emily Harvard, Katherine Cherry, Claudia R. Benitez-Nelson, Eric Tappa, Catherine V. Davis

Faculty Publications

The rapid response of foraminiferal assemblages to changing climate makes their shells an invaluable geological record of the past. However, the time frame over which foraminifera respond to climatic signals and the specific drivers influencing assemblage composition and abundance remain obscure. We focus on the impact of ongoing, anthropogenic climate change on planktic foraminifera in the California Current ecosystem, which would appear as a nearly instantaneous event in the sediment record. The Santa Barbara Basin sediment trap, located off the coast of California, USA since 1993, provides a record of more than 30 years of particulate and foraminiferal flux in …

A 12,800-Year-Old Layer With Cometary Dust, Microspherules, And Platinum Anomaly Recorded In Multiple Cores From Baffin Bay, Christopher R. Moore, Vladimir A. Tselmovich, Malcolm A. Lecompte, Allen West, Stephen J. Culver, David J. Mallinson, Mohammed Baalousha M.Sc, Ph.D., James P. Kennett, William M. Napier, Michael Bizimis, Victor Adedeji, Seth R. Sutton, Gunther Kleteschka, Kurt A. Langworthy, Jesus P. Perez, Timothy Witwer, Marc D. Young, Jordan Jeffreys, Richard C. Greenwood, James A. Malley

Faculty Publications

The Younger Dryas Impact Hypothesis (YDIH) posits that ~12,800 years ago Earth encountered the debris stream of a disintegrating comet, triggering hemisphere-wide airbursts, atmospheric dust loading, and the deposition of a distinctive suite of extraterrestrial (ET) impact proxies at the Younger Dryas Boundary (YDB). Until now, evidence supporting this hypothesis has come only from terrestrial sediment and ice-core records. Here we report the first discovery of similar impact-related proxies in ocean sediments from four marine cores in Baffin Bay that span the YDB layer at water depths of 0.5–2.4 km, minimizing the potential for modern contamination. Using scanning electron microscopy …

Expanded Genetic And Functional Diversity Of Oceanic Fungi, Xuefeng Peng, David L. Valentine

Faculty Publications

Background

Fungi are known members of marine microbiomes that can act as saprotrophs, parasites, and pathogens. Although a few studies utilizing cultivation-based methods and metabarcoding have been conducted, the diversity, ecological roles, and functional activities of fungi in the open ocean remain vastly underexplored. This gap in knowledge is particularly notable in oxygen minimum zones (OMZ) of the ocean, which have expanded over the past 50 years, affecting marine ecosystems and biogeochemical cycles. The eastern tropical North Pacific Ocean (ETNP) is the largest oxygen minimum zone where fungi have been implicated in the production of the potent greenhouse gas nitrous …

Basil And Swiss Chard: Edible Crops For Use In Floating Treatment Wetlands Improving Agricultural Runoff, Clare Escamilla, David R. Tyrpak, William H.J. Stronsnider, Sarah A. White

Faculty Publications

The plant species established within floating treatment wetlands (FTWs) influence nutrient removal efficiency. To enhance adoption of FTWs by agricultural producers, both economic and ecological benefits from FTWs are needed to increase their use within irrigation retention reservoirs. Thus, we ascertained the feasibility of growing food crops in FTWs by evaluating two edible plant species to determine survivability and nutrient accumulation when grown in FTWs. We quantified plant growth (at saleable/harvestable size), nutrient uptake in root and shoot tissues, and overall nutrient removal efficiency of sweet basil (Ocimum basilicum) and Swiss chard (Beta vulgaris) over a …

Urbanization Impacts Dissolved Organic Matter Concentration And Quality In A Southeastern United States Watershed, Gwendolyn M. Hopper, Erik M. Smith, Jade Dormoy-Boulanger, Claudia R. Benitez-Nelson

Faculty Publications

Blackwater rivers are named due to their exceptionally high concentrations of chromophoric dissolved organic matter (CDOM). They are the predominant lotic ecosystem in the United States Southeastern Coastal Plain, a region experiencing some of the nation’s highest rates of development. This study assessed variability in DOM concentration and composition across forested to urbanized blackwater systems in coastal South Carolina, U.S. Dissolved organic carbon and nutrient concentrations as well as absorbance and fluorescence optical properties reveal that urban sites have lower concentrations, elemental ratios, and less complex DOM. In contrast, forested blackwater sites have concentrations an order of magnitude higher, elevated …

Heterogeneous Mantle Effects On The Behaviour Of Smks Waves And Outermost Core Imaging, Daniel A. Frost, Edward J. Garnero, Neala Creasy, Jonathan Wolf, Ebru Bozdağ, Maureen D. Long, Adeolu Aderoju, Reynaldo Vite

Faculty Publications

Seismic traveltime anomalies of waves that traverse the uppermost 100–200 km of the outer core have been interpreted as evidence of reduced seismic velocities(relative to radial reference models) just below the core–mantle boundary (CMB). These studies typically investigate differential traveltimes of SmKS waves, which propagate as P waves through the shallowest outer core and reflect from the underside of the CMB m times. The use of SmKS and S(m-1)KS differential traveltimes for core imaging are often assumed to suppress contributions from earthquake location errors and unknown and unmodelled seismic velocity heterogeneity in the mantle. The goal of this study is …

Understanding The Role Of The Jet Streams And Gulf Stream Eddies On The Northwest Atlantic Marine Heatwaves, Lydia Rose Duncan Sims

Theses and Dissertations

The Northwest (NW) Atlantic is one of the fastest warming regions in the global ocean and in the recent decade has experienced several extreme temperature events. These extreme anomalous temperature events are known as Marine Heatwaves (MHWs), which are forced by a variety of physical processes that affect the heat source and sink of the water column. These MHWs have been increasing globally in duration and frequency due to anthropogenic warming, and have increased ecological damage seen in mass mortality events of economically viable species. Within the NW Atlantic, several key processes encourage the formation of MHWs, such as the …

Soil Organic Matter Diagenetic State Informs Boreal Forest Ecosystem Feedbacks To Climate Change, Allison N. Myers-Pigg, Karl Kaiser, Ronald Benner, Susan E. Ziegler

Faculty Publications

The fate of soil organic carbon (SOC) in boreal forests is dependent on the integrative ecosystem response to climate change. For example, boreal forest productivity is often nitrogen (N) limited, and climate warming can enhance N cycling and primary productivity. However, the net effect of this feedback on the SOC reservoir and its longevity with climate change remain unclear due to difficulty in detecting small differences between large and variable carbon (C) fluxes needed to determine net changes in soil reservoirs. The diagenetic state of SOC – resulting from the physicochemical and biological transformations that alter the original biomolecular composition …

Tropical Cyclone And Ocean-Atmosphere Interactions In The Gulf Of Mexico, Emily Nichole Eley

Theses and Dissertations

The Gulf of Mexico (GoM) is historically a favorable region for the formation, maintenance and intensification of tropical cyclones that frequently evolve into powerful hurricanes. These natural disasters threaten the basin’s innate habitat and wildlife diversity, and the expansive coastal economies and communities. The dominant ocean circulation feature in the GoM is the Loop Current System (LCS) which includes the Loop Current (LC) and its associated mesoscale eddy field. The LC originates at the Yucatán Channel, loops anticyclonically into the basin, and ends at the Florida Straits; further it produces both anticyclonic and cyclonic eddies. The existence of the LCS …

Sources And Cycling Of Neodymium And Rare Earth Elements In The Arctic Amerasian Basin And Bering Sea, Brian D. Duggan

Theses and Dissertations

The isotopic composition of dissolved neodymium (¹⁴³Nd/¹⁴⁴Nd, expressed as εNd) behaves quasi-conservatively in the ocean and has been used as a palaeoceanographic tracer of ocean circulation. The εNd value of water masses is acquired—and often altered—during interaction with sediments along the margins; however, the processes involved in seawater εNd acquisition remains poorly characterized and quantified. Here we report the results of 349 Nd isotope and 354 rare earth element (REE) concentration measurements from 27 water column profiles across the Bering shelf and through the Arctic Amerasian Basin collected during U.S. Arctic GEOTRACES cruise HLY1502 (GEOTRACES section …

Arctic Ocean And Subarctic Seas Dynamics In A Changing Climate, Sarah B. Hall

Theses and Dissertations

Salinity is the primary determinant of the Arctic Ocean’s vertical density stratification in the upper ocean, which has major implications on the ocean’s physical dynamics alongside a period of rapidly declining sea ice. In recent decades, the Arctic’s freshwater content (FWC) has increased as a result of the accumulation of freshwater source inputs. Additional freshwater exported to the North Atlantic may hinder overturning processes that are vital to the regulation of global climate. This dissertation employs in situ measurements, satellite observations, and ocean model simulations to better understand salinity and freshwater changes in the Arctic Ocean during this changing climate. …

Carbon In The Deep Biosphere: Forms, Fates, And Biogeochemical Cycling, Susan Q. Lang, Magdalena R. Osburn, Andrew D. Steen

Faculty Publications

Building on the synthesis of carbon reservoirs in Earth's subsurface, this chapter focuses on the forms, cycling, and fate of the carbon supporting microbial life in the terrestrial and marine subsurface. As the subsurface is estimated to host a vast reservoir of life on Earth, identifying the carbon compounds that life uses for energy and growth is key to understanding ecosystem functioning in the past and at present, and also for extrapolating these findings to the search for life in the universe. This chapter highlights advances in quantifying small carbon compounds, measuring rates of carbon turnover, and the fate of …

An Implementation Strategy To Quantify The Marine Microbial Carbon Pump And Its Sensitivity To Global Change, Carol Robinson, Douglas Wallace, Jung-Ho Hyun, Luca Polimene, Ronald Benner, Yao Zhang, Ruanhong Cai, Rui Zhang, Nianzhi Jiao

Faculty Publications

No abstract provided.

Mixing It Up In The Ocean Carbon Cycle And The Removal Of Refractory Dissolved Organic Carbon, Yuan Shen, Ronald Benner

Faculty Publications

A large quantity of reduced carbon is sequestered in the ocean as refractory dissolved molecules that persist through several circuits of global overturning circulation. Key aspects of the cycling of refractory dissolved organic carbon (DOC) remain unknown, making it challenging to predict how this large carbon reservoir will respond to climate change. Herein we investigate mechanisms that remove refractory DOC using bioassay experiments with DOC isolated from surface, mesopelagic and deep waters of the Atlantic Ocean. The isolated DOC was refractory to degradation by native microbial communities, even at elevated concentrations. However, when the refractory DOC was introduced to a …

Shelf Cross-Shore Flows Under Storm-Driven Conditions: Role Of Stratification, Shoreline Orientation, And Bathymetry., Xiaodong Wu, Nirnimesh Kumar, George Voulgaris

Faculty Publications

Numerical simulations are used to study the response of Long Bay, SC (USA), a typical coastal embayment with curved coastline located on the South Atlantic Bight, to realistic, climatologically defined, synoptic storm forcing. Synoptic storms, consisting of cold and warm 25 fronts as well as tropical storms, are used as forcing under both mixed and stratified initial conditions. The analysis focuses on the development of cross-shore shelf circulation and the relative contributions of regionally defined cross-shore winds and alongshore bathymetric variation. The simulation results show that, under stratified conditions, the regionally defined offshore directed wind component promotes upwelling during the …

Biochemical And Structural Controls On The Decomposition Dynamics Of Boreal Upland Forest Moss Tissues, Michael Philben, Sara Butler, Sharon A. Billings, Ronald Benner, Kate A. Edwards, Susan E. Ziegler

Faculty Publications

Mosses contribute an average of 20 % of boreal upland forest net primary productivity and are frequently observed to degrade slowly compared to vascular plants. If this is caused primarily by the chemical complexity of their tissues, moss decomposition could exhibit high temperature sensitivity (measured as Q10) due to high activation energy, which would imply that soil organic carbon (SOC) stocks derived from moss remains are especially vulnerable to decomposition with warming. Alternatively, the physical structure of the moss cell-wall biochemical matrix could inhibit decomposition, resulting in low decay rates and low temperature sensitivity. We tested these hypotheses by …

A Recent Project Shows That The Microbial Carbon Pump Is A Primary Mechanism Driving Ocean Carbon Uptake, Jing M. Chen, Louis Legendre, Ronald Benner

Faculty Publications

No abstract provided.

Biological Hot Spots And The Accumulation Of Marine Dissolved Organic Matter In A Highly Productive Ocean Margin, Yuan Shen, Cédric G. Fichot, Sheng-Kang Liang, Ronald Benner

Faculty Publications

Concentrations of dissolved organic carbon (DOC) and major biochemicals (amino acids and carbohydrates) were measured during five cruises (2009–2010) to the Louisiana margin in the northern Gulf of Mexico. Concentrations of amino acids and carbohydrates were elevated at mid-salinities and were indicative of plankton production of dissolved organic matter (DOM) in surface waters. Hot spots of two compositionally distinct types of labile DOM were identified based on the relative abundances of amino acids and carbohydrates. Amino acid-rich hot spots occurred sporadically in regions of high phytoplankton biomass and were mostly observed between dusk and dawn, reflecting a grazing source. In …

Isotopic (Δ13c, Δ14c) Analysis Of Organic Acids In Marine Samples Using Wet Chemical Oxidation, Susan Q. Lang, G. L. Früh-Green, S. M. Bernasconi, L. Wacker

Faculty Publications

We present a method for the isolation and off-line isotope analysis of formate and acetate in marine samples. Organic acids are separated by high performance liquid chromatography and collected in glass Exetainer® screw-capped vials that have been prespiked with an oxidant and flushed with helium. The vials are subsequently heated to convert the organic compounds to CO₂ for radiocarbon and δ¹³C analysis. Small aliquots are sampled for measurement of δ¹³C by isotope ratio mass spectrometry, whereas the majority of the CO₂ is saved for radiocarbon analysis by accelerator mass spectrometry using a gas ion …

A Physiochemically Constrained Seawater Culturing System For Production Of Benthic Foraminifera, Christopher J. Hintz, G. Thomas Chandler, Jay M. Bernhardt, Daniel C. Mccorkle, Suzanne M. Havach, Jessica K. Blanks, Timothy J. Shaw

Faculty Publications

No abstract provided.

Methods And Models For Estimating Advective Pore Water Exchange In Tidal Flats, Timothy J. Shaw

Faculty Publications

No abstract provided.

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw

Faculty Publications

No abstract provided.