Oceanography and Atmospheric Sciences and Meteorology Commons^™

Sensitivity Of The Relationship Between Antarctic Ice Shelves And Iron Supply To Projected Changes In The Atmospheric Forcing, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken

CCPO Publications

Upward advection or mixing of iron-rich deep waters due to circulation changes driven by the rate of basal ice shelf melt was shown to be a primary control on chlorophyll a production in coastal polynyas over the Antarctic continental shelf. Here, the effects of atmospheric changes projected in 2100 on this relationship were examined with a 5-km resolution ocean/sea ice/ice shelf model of the Southern Ocean with different simulated dissolved iron sources and idealized biological uptake. The atmospheric changes are added as idealized increments to the forcing. Inclusion of a poleward shift and strengthening of the winds, increased precipitation, and …

An Analysis Of Tidal Mixing Front Dynamics And Frontal Biophysical Interaction In The Harpswell Sound Shelf Sea, Lemona Yingzhuo Niu

Honors Projects

Tidal Mixing Fronts (TMFs) are prominent hydrographic features of tidally energetic shallow shelf seas, representing the transition from mixed to stratified waters. These frontal boundaries often host enhanced phytoplankton primary productivity, as complete vertical mixing exhumes nutrients from depth to the light-lit surface. Existing observational programs for locating TMFs include infra-red satellite imagery of sea surface temperature (SST) and vertical profiling of temperature and density. However, challenges in observationally distinguishing mixed from mixing using only conservatively mixed hydrographic properties persist. A novel approach based on phytoplankton in-situ oxygen production response to light is proposed in this paper to distinguish stable …

Nitrite Cycling In The Primary Nitrite Maxima Of The Eastern Tropical North Pacific, Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, Karen L. Casciotti

OES Faculty Publications

The primary nitrite maximum (PNM) is a ubiquitous feature of the upper ocean, where nitrite accumulates in a sharp peak at the base of the euphotic zone. This feature is situated where many chemical and hydrographic properties have strong gradients and the activities of several microbial processes overlap. Near the PNM, four major microbial processes are active in nitrite cycling: ammonia oxidation, nitrite oxidation, nitrate reduction and nitrite uptake. The first two processes are mediated by the nitrifying archaeal/bacterial community, while the second two processes are primarily conducted by phytoplankton. The overlapping spatial habitats and substrate requirements for these microbes …

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 …

Insights Into The Deglacial Variability Of Phytoplankton Community Structure In The Eastern Equatorial Pacific Ocean Using [231Pa/230Th]Xs And Opal-Carbonate Fluxes, Danielle Schimmenti, Franco Marcantonio, Christopher T. Hayes, Jennifer Hertzberg, Matthew Schmidt, John Sarao

OES Faculty Publications

Fully and accurately reconstructing changes in oceanic productivity and carbon export and their controls is critical to determining the efficiency of the biological pump and its role in the global carbon cycle through time, particularly in modern CO₂ source regions like the eastern equatorial Pacific (EEP). Here we present new high-resolution records of sedimentary ²³⁰Th-normalized opal and nannofossil carbonate fluxes and [²³¹Pa/²³⁰Th]xs ratios from site MV1014-02-17JC in the Panama Basin. We find that, across the last deglaciation, phytoplankton community structure is driven by changing patterns of nutrient (nitrate, iron, and silica) availability which, in …

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

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 …

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 …

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 …

Water Quality Assessment In The Occurrence Of Acanthaster Spp. (Crown-Of-Thorns Starfish, Cots) On Coral Reefs In Menjangan Island, Bali, Indonesia, Novia Arinda Pradisty, Eghbert Elvan Ampou, Rizki Hanintyo

Makara Journal of Science

Aquatic stressors are known to cause biological impairment that can result in biodiversity loss in several Marine Protected Areas (MPA), including in Menjangan Island, West Bali National Park. The objectives of this study were to correlate the changes in water quality parameters with the biological effect of Crown-of-Thorns starfish (CoTS) population dynamics and to assess the most applicable parameters for continuous environmental monitoring. Field observations and surveys were conducted three times in 2017, during the wet season, dry season and season transition, in order to assess the effect of seasonal variability. Redundancy Analysis (RDA) was performed to determine the relationship …

Organic Sulfur: A Spatially Variable And Understudied Component Of Marine Organic Matter, Krista Longnecker, Lisa Oswald, Melissa C. Kido Soule, Gregory A. Cutter, Elizabeth B. Kujawinski

OES Faculty Publications

Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecular-level composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass …

Temporal And Spatial Scales Of Correlation In Marine Phytoplankton Communities, A. M. Kuhn, S. Dutkiewicz, O. Jahn, Sophie Clayton, T. A. Rynearson, M. R. Mazloff, A. D. Barton

OES Faculty Publications

Ocean circulation shapes marine phytoplankton communities by setting environmental conditions and dispersing organisms. In addition, processes acting on the water column (e.g., heat fluxes and mixing) affect the community structure by modulating environmental variables that determine in situ growth and loss rates. Understanding the scales over which phytoplankton communities vary in time and space is key to elucidate the relative contributions of local processes and ocean circulation on phytoplankton distributions. Using a global ocean ecosystem model, we quantify temporal and spatial correlation scales for phytoplankton phenotypes with diverse functional traits and cell sizes. Through this analysis, we address these questions: …

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

Iron Fertilization With Enhanced Phytoplankton Productivity Under Minimal Sulfur Compounds And Grazing Control Analysis In Hnlc Region, Tai-Jin Kim, G. H. Hong, D. G. Kim Kim, Mark Baskaran

Environmental Science and Geology Faculty Research Publications

The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the im- proved iron fertilization for climate change. The limitation of iron (Fe) for phytoplankton growth in HNLC regions was confirmed by sulfur compounds (S) such as volcanic ash and hydrogen sulfide (H2S) in batch cultures, whose chemical sediment of Fe3S4 showed 4.06 wt%. The technologies developed for iron fertilization since 1993 till now were not practical to provide sufficient amounts of bioavailable iron due to sedimentary iron sulfides induced by undersea volcanic sulfur compounds. The proposed technology for iron fertilization was improved …

Interpreting Mosaics Of Ocean Biogeochemistry, Andrea Fassbender, A. Bourbonnais, Sophie Clayton, P. Gaube, M. Ormand, P.J.S. Franks, M. A. Altabet, D.J. Mcgillicuddy Jr.

OES Faculty Publications

Advances in technology and modeling capabilities are driving a surge in progress in our understanding of how ocean ecosystems mix and mingle on medium to small scales.

Exploration Of Spatial And Temporal Changes In Trophic Status Of Lakes In The Northern Temporal Forest Biome Using Remote Sensing, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a critical need for detailed surveys of lakes covering large spatial (>100 km²) and temporal scales (decades) to determine if there is an increase in the magnitude and frequency of phytoplankton blooms. Remote sensing was used to: (1) develop a regression model that relates chlorophyll a (chl-a) as a proxy of lake phytoplankton biomass to Landsat TM and ETM+ optical reflectance (r²=0.85, p

Iron Supply And Demand In Antarctic Shelf Ecosystem, D. J. Mcgillicuddy Jr., Peter N. Sedwick, Michael S. Dinniman, K. R. Arrigo, T. S. Bibby, B. J. W. Greenan, Eileen E. Hofmann, John M. Klinck, W. O. Smith Jr., S. L. Mack, C. M. Marsay, B. M. Sohst, G. L. Van Dijken

OES Faculty Publications

The Ross Sea sustains a rich ecosystem and is the most productive sector of the Southern Ocean. Most of this production occurs within a polynya during the November-February period, when the availability of dissolved iron (dFe) is thought to exert the major control on phytoplankton growth. Here we combine new data on the distribution of dFe, high-resolution model simulations of ice melt and regional circulation, and satellite-based estimates of primary production to quantify iron supply and demand over the Ross Sea continental shelf. Our analysis suggests that the largest sources of dFe to the euphotic zone are wintertime mixing and …

Phytoplankton And Nutrient Dynamics In A Tidally Dominated Eutrophic Estuary: Daily Variability And Controls On Bloom Formation, Ryan E. Morse, Margaret R. Mulholland, Todd A. Egerton, Harold G. Marshall

OES Faculty Publications

To better understand nutrient dynamics and factors that promote the initiation of algal blooms, the Lafayette River, a tidal subestuary of Chesapeake Bay that experiences seasonal algal blooms, was sampled daily for a period of 54 d in the fall of 2005. Three phytoplankton blooms (chl a concentrations exceeding twice the average of monthly measurements from 2000 to 2009) occurred during this period: a mixed bloom of Akashiwo sanguinea and Gymnodinium sp., a monospecific Skeletonema costatum bloom, and a monospecific Gymnodinium sp. bloom. Over the sampling period, nutrient concentrations increased following precipitation events and were elevated between bloom periods but …

The Great 2012 Arctic Ocean Summer Cyclone Enhanced Biological Productivity On The Shelves, Jinlun Zhang, Carin Ashjian, Robert Campbell, Victoria Hill, Yvette H. Spitz, Michael Steele

OES Faculty Publications

A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and …

Springtime Contribution Of Dinitrogen Fixation To Primary Production Across The Mediterranean Sea, E. Rahav, B. Herut, A. Levi, Margaret Mulholland, I. Berman-Frank

OES Faculty Publications

Dinitrogen (N-2) fixation rates were measured during early spring across the different provinces of Mediterranean Sea surface waters. N-2 fixation rates, measured using N-15(2) enriched seawater, were lowest in the eastern basin and increased westward with a maximum at the Strait of Gibraltar (0.10 to 2.35 nmol NL-1 d(-1), respectively). These rates were 3-7 fold higher than N-2 fixation rates measured previously in the Mediterranean Sea during summertime and we estimated that methodological differences alone did not account for the seasonal changes we observed. Higher contribution of N-2 fixation to primary production (4-8 %) was measured in the western basin …

Distributions Of Particulate Heme B In The Atlantic And Southern Oceans- Implications For Electron Transport In Phytoplankton, Martha Gledhill, Eric P. Achterberg, David J. Honey, Maria C. Nielsdottir, Micha J.A. Rijkenberg

OES Faculty Publications

Concentrations of heme b, the iron-containing component of b-type hemoproteins, ranged from b concentrations were enhanced in the photic zone and decreased with depth. Heme b concentrations correlated positively with chlorophyll a (chl a) in the TNA (r=0.41, pb did not correlate with chl a in the IB or SS. In the IB and SS, stations with high-chlorophyll and low-nutrient (Fe and/or Si) concentrations exhibited low heme bconcentrations relative to particulate organic carbon (< 0.1 μmolmol^-1, and high chl a:heme b ratios (> 500). High chl a:heme b ratios resulted from relative decreases in …

Phosphorus Cycling In The Sargasso Sea: Investigation Using The Oxygen Isotopic Composition Of Phosphate, Enzyme-Labeled Fluorescence, And Turnover Times, Karen Mclaughlin, Jill A. Sohm, Gregory A. Cutter, Michael W. Lomas, Adina Paytan

OES Faculty Publications

Dissolved inorganic phosphorus (DIP) concentrations in surface water of vast areas of the ocean are extremely low (<10 nM) and phosphorus (P) availability could limit primary productivity in these regions. We explore the use of oxygen isotopic signature of dissolved phosphate (δ¹⁸O_PO4) to investigate biogeochemical cycling of P in the Sargasso Sea, Atlantic Ocean. Additional techniques for studying P dynamics including ³³P-based DIP turnover time estimates and percent of cells expressing alkaline phosphatase (AP) activity as measured by enzyme-labeling fluorescence are also used. In surface waters, δ¹⁸O_PO4 values were lower than equilibrium by 3–6%, indicative of dissolved organic phosphorous (DOP) remineralization by extracellular enzymes. An isotope mass balance model using a variety of possible combinations of …

Production Of Bioactive Secondary Metabolites By Florida Harmful Bloom Dinoflagellates Karenia Brevis And Pyrodinium Bahamense, Cheska Burleson

USF Tampa Graduate Theses and Dissertations

Despite the critical role algae serve as primary producers, increases or accumulation of certain algae may result in Harmful Algal Blooms (HABs). Algal toxins from these blooms contribute significantly to incidences of food borne illness, and evidence suggests HABs are expanding in frequency and distribution. Mitigation of these HABs without knowledge of the ecological purpose and biochemical regulation of their toxins is highly unlikely. The production, function, and potential of secondary metabolites produced by the dinoflagellates Karenia brevis and Pyrodinium bahamense, were investigated.

Brevetoxins were demonstrated by two different methods to localize within the cytosol of Karenia brevis. …

Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio

OES Faculty Publications

The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO₂sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (~ 0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show …

On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church

OES Faculty Publications

Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and …

Co2 Sensitivity Of Southern Ocean Phytoplankton, Philippe D. Tortell, Christopher D. Payne, Yingyu Li, Scarlett Trimborn, Bjorn Rost, Walker O. Smith, Christina Riesselman, Robert B. Dunbar, Peter Sedwick, Giacomo R. Ditullio

OES Faculty Publications

The Southern Ocean exerts a strong impact on marine biogeochemical cycles and global air-sea CO₂ fluxes. Over the coming century, large increases in surface ocean CO₂ levels, combined with increased upper water column temps. and stratification, are expected to diminish Southern Ocean CO₂ uptake. These effects could be significantly modulated by concomitant CO₂-dependent changes in the region's biol. carbon pump. Here we show that CO₂ concentrations affect the physiology, growth and species composition. of phytoplankton assemblages in the Ross Sea, Antarctica. Field results from in situ sampling and ship-board incubation experiments demonstrate that inorganic …

The Observation, Modeling, And Retrieval Of Bio-Optical Properties For Coastal Waters Of The Southern Chesapeake Bay, Xiaoju Pan

OES Theses and Dissertations

The primary purpose of this study was to develop an inverse method to retrieve the inherent optical properties (IOPs) and biogeochemical parameters (e.g. chlorophyll a concentration and salinity) appropriate to monitor the water quality and biogeochemical processes from remote sensing of the coastal waters in the southern Chesapeake Bay and coastal Mid-Atlantic Bight region (MAB) dominated by Case 2 waters. For this purpose, knowledge of the relationship between remote sensing reflectance (R_rs) and IOPs and the effect from bottom reflectance on R_rs, is required.

A substantial investigation of IOPs has been conducted for the coastal …

Evaluating The Biogeochemical Cycle Of Selenium In San Francisco Bay Through Modeling, Shannon L. Meseck, Gregory A. Cutter

OES Faculty Publications

A biogeochemical model was developed to simulate salinity, total suspended material, phytoplankton biomass, dissolved selenium concentrations (selenite, selenate, and organic selenide), and particulate selenium concentrations (selenite + selenate, elemental selenium, and organic selenide) in the San Francisco Bay estuary. Model-generated estuarine profiles of total dissolved selenium reproduced observed estuarine profiles at a confidence interval of 91- 99% for 8 different years under various environmental conditions. The model accurately reproduced the observed dissolved speciation at confidence intervals of 81-98% for selenite, 72-91% for selenate, and 60-96% for organic selenide. For particulate selenium, model-simulated estuarine profiles duplicated the observed behavior of total …

A Unique Seasonal Pattern In Phytoplankton Biomass In Low-Latitude Waters In The South China Sea, Chun-Mao Tseng, George T. F. Wong, I.-I. Lin, C.-R. Wu, K.-K. Liu

OES Faculty Publications

A distinctive seasonal pattern in phytoplankton biomass was observed at the South East Asian Time series Study (SEATS) station (18°N, 116°E) in the northern South China Sea (SCS). Surface chlorophyll-a, depth integrated chlorophyll-a and primary production were elevated to 0.3 mg/m³, ~35 mg/m² and 300 mg-C/m²/d, respectively, in the winter but stayed low, at 0.1 mg/m³, ~15 mg/m² and 110 mg-C/m²/d as commonly found in other low latitude waters, in the rest of the year. Concomitantly, soluble reactive phosphate and nitrate+nitrite in the mixed layer also became …

Uptake Of Dissolved Organic Selenides By Marine Phytoplankton, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter

OES Faculty Publications

Se is present in multiple oxidation states in nature, each of which has unique chemical and biological reactivities. As a consequence, the rate of Se incorporation into food webs or its role as either a limiting nutrient or a toxic substance is a function of complex biogeochemistry. In particular, little is understood about the accumulation of dissolved organic selenides by phyto- or bacterioplankton. We assessed the bioavailability of dissolved organic selenides to marine and estuarine phytoplankton by presenting various algal species with filtered lysates of the diatom, Thalassiosira pseudonana, grown on media amended with radiolabeled selenite (⁷⁵Se[IV]). …