Biogeochemistry Commons^™

Autonomous Float Data Reveal Decoupled Trends In Chlorophyll And Stratification In The Indian Ocean, Marufa Ishaque, Sophie Clayton, John Klinck

OES Faculty Publications

Recent studies have shown that the Indian Ocean is warming significantly, but how this warming impacts primary production is largely unresolved due to a relative lack of depth-resolved biological observations. In this study, we have used Biogeochemical-Argo data from 2013 to 2022, comprising over 9,000 individual profiles, to examine regional patterns and trends in depth-integrated chlorophyll, depth-integrated net primary production and stratification in the northern and Equatorial Indian Ocean. Our analysis shows that water column stratification is increasing in the majority of the study area, with the highest rate of increase observed in the western Bay of Bengal. At the …

Comparison Of Nutrient Concentrations And Primary Production Indicators Across Plume Fronts, Taylor Dishon

Electronic Theses and Dissertations

Coastal buoyant plumes carry low-salinity waters containing particulate and dissolved terrestrial materials with an abundance of nutrients into the coastal ocean, including inorganic nitrogen and phosphorous. Plume fronts act as transport barriers created from the convergence of a fresher plume with an older, saltier plume or with ambient waters, leading to potential accumulation of phytoplankton and nutrients. This accumulation creates an optimal environment for primary production. The primary goals of this study were: to investigate the distribution of and potential relationships between nutrient concentrations and chlorophyll a across plume fronts of the Winyah Bay River Plume, and examine potential relationships …

Effects Of Urbanization On Eutrophication Parameters In Three Tidal Creeks, Ella Swantek

Honors Theses

Marshes and swashes are vital environments as a controlling barrier between land affected by various pollutants and the ocean. Eutrophication and the effects of this process can be detrimental for the areas experiencing it. I am interested in ways areas that have little contact with human interactions compare to areas that are heavily urbanized, and whether either of these locations is at a higher risk for eutrophication. Using spectrophotometry and fluorometry, I analyzed samples collected from the relatively undeveloped and restricted-access locations of Waities Island Beach and Dunn Sound monthly for dissolved nutrients, and chlorophyll. At the time of sampling, …

Impacts Of Hurricane Idalia’S Surge On Coastal Sand Biogeochemistry, Wendy "Cor" Mchone

Honors Theses

Beaches are heavily influenced by extreme events, such as hurricanes. Biological and chemical processes, such as primary production and diagenesis are often interrupted by these events. To examine the effects of hurricanes on coastal biogeochemistry, this study used sand and porewater samples from Waties Island, SC, which were collected before and after Hurricane Idalia. The samples were analyzed for macronutrient concentrations, organic content, and chlorophyll concentrations. Macronutrient pore water concentration changes were not uniform. The inventory of nitrite decreased significantly after the storm, which was reflected in slight increases in the inventories of nitrate and ammonium. Concentrations of nitrate, which …

Sedimentary Conditions At A Tidal Creek That Exhibits Seasonal Pelagic-Benthic Variations, Jack B. Corbin

Honors Theses

Tidal creeks in the Grand Strand of South Carolina are small but numerous connectors between land and ocean. One of these creeks, White Point Swash, exhibits a seasonal switch between planktonic and benthic photosynthesizers. As plankton become less abundant in fall, benthic macroalgae bloom, aided by lower water levels due to fall-winter dredging of the main channel, until late Spring. This study builds on previous findings and examines sedimentary conditions at this site further. Sedimentary chlorophyll a (in microphytobenthos) and pore water nutrient concentrations are confirmed to be higher than water-column concentrations. Sedimentary nutrient fluxes to the sediment-water interface, calculated …

Unraveling Sources Of Cyanate In The Marine Environment: Insights From Cyanate Distributions And Production During The Photochemical Degradation Of Dissolved Organic Matter, Rui Wang, Jihua Liu, Yongle Xu, Li Liu, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Cyanate is a nitrogen and energy source for diverse marine microorganisms, playing important roles in the nitrogen cycle. Despite the extensive research on cyanate utilization, the sources of this nitrogen compound remain largely enigmatic. To unravel the sources of cyanate, distributions and production of cyanate during photochemical degradation of natural dissolved organic matter (DOM) were investigated across various environments, including freshwater, estuarine, coastal areas in Florida, and the continental and slope regions of the North American mid-Atlantic Ocean (NATL). Cyanate production was also examined during the photochemical degradation of exudates from a typical strain of Synechococcus, an important phytoplankton …

A New View Of Chlorophyll Dynamics In The Southern Mid-Atlantic Bight From A Two-Year High-Resolution Spray Glider Survey, Francesco Lane

OES Theses and Dissertations

The southern Mid-Atlantic Bight (MAB) near Cape Hatteras, NC, USA, is likely a hotspot for the episodic export of carbon-rich shelf waters to the open ocean. Over a 2 year period, from March 2017 to May 2019, Spray gliders repeatedly occupied transects, along the slope and across the shelf, generating high-resolution chlorophyll fluorescence (fChl) data in the southern MAB. This study implements an fChl calibration method utilizing remotely sensing ocean color as a standard. We validate the method’s utility by demonstrating a reduction in post-calibration cross-mission fChl variability and demonstrating close correspondence between the calibrated fChl data and an in …

Authigenic Iron Is A Significant Component Of Oceanic Labile Particulate Iron Inventories, Laura E. Sofen, Olga A. Antipova, Kristen N. Buck, Salvatore Caprara, Lauren Chacho, Rodney J. Johnson, Gabriella Kim, Peter Morton, Daniel C. Ohnemus, Sara Rauschenberg, Peter N. Sedwick, Alessandro Tagliabue, Benjamin S. Twining

OES Faculty Publications

Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile …

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.

Characterizing Freshwater Phytoplankton Dynamics With Electro-Optical Remote Sensing, Michael Sayers

Dissertations, Master's Theses and Master's Reports

Freshwater lakes are an important component contributing to ecosystem health and biodiversity on local, regional, and global scales. And while lakes only represent <5% of the global surface area, they are often very productive systems which contribute significantly to carbon cycling dynamics and freshwater fish production on a number of spatial scales. Due to the remote location and sheer size of some of these lakes it has proven difficult to adequately document changes in water quality. Significant challenges exist to adequately monitor water quality, and in particular phytoplankton dynamics, over large spatial and temporal scales using traditional in situ methods. Satellite electro-optical remote sensing offers a potential tool to provide better characterization of phytoplankton dynamics for a variety of freshwater systems. This work resulted in an approach to quantify global summer phytoplankton abundance using a newly developed remote sensing derived chlorophyll-a product. This product was also used in conjunction with a newly created carbon fixation model to assess global freshwater phytoplankton production which provided new insights into the role freshwater systems play in the …

Characterizing Diatom Biofilms And Their Influence On The Sand Biogeochemistry Of High Energy Beaches, Logan C. Jarrell

Honors Theses

High energy beaches are among the most dynamic ecological settings on Earth. Compared to mudflats, diatoms of high energy beaches have been more neglected in the literature, particularly true of the intertidal biofilms that form and dissipate with nutrient cycling and light intensity over the tidal cycle. Although short lived, the productivity of these biofilms may be critical to the organic-poor sand. Through sediment coring and subsequent analyses of the uppermost sand of three suspected biofilm stations—non-runnel, runnel crest, and runnel trough—along with seemingly bare sand as a control, this study sought to verify the presence of diatom biofilms and …

Dissolved Oxygen Dynamics During A Phytoplankton Bloom In The Ross Sea Polyna, Bastien Y. Queste, Karen J. Heywood, Walker O. Smith Jr., Daniel E. Kaufman, Timothy D. Jickells, Michael S. Dinniman

CCPO Publications

The Ross Sea polynya is one of the most productive regions in the Southern Ocean. However, limited access and high spatio-temporal variability of physical and biological processes limit the use of conventional oceanographic methods to measure early season primary productivity. High-resolution observations from two Seagliders provide insights into the timing of a bloom in the southern Ross Sea polynya in December 2010. Changes in chlorophyll and oxygen concentrations are used to assess bloom dynamics. Using a ratio of dissolved oxygen to carbon, net primary production is estimated over the duration of the bloom showing a sensitive balance between net autotrophy …

The Biogeochemistry Of Hydrogen Sulfide In The Open Ocean, Joël Radford-Knoery

OES Theses and Dissertations

Hydrogen sulfide is a poorly quantified component of the global sulfur cycle. In seawater, its dissolved species (dissolved sulfide) can react with trace metals to form dissolved complexes and insoluble compounds. Therefore, the study of dissolved° sulfide in the open ocean can yield a better understanding of the biogeochemical cycles of sulfur and trace metals.

The biogeochemical cycling of dissolved sulfide was examined using specially developed sampling and analytical methods. In the western North Atlantic and central Equatorial Pacific Oceans, total dissolved sulfide concentrations ranged from /L; they were highest, in the mixed layer and decreased with depth. The depth …