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OES Faculty Publications

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Articles 301 - 330 of 496

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Iron Limitation Of A Springtime Bacterial And Phytoplankton Community In The Ross Sea: Implications For Vitamin B12 Nutrition, Erin M. Bertrand, Mak A. Saito, Peter A. Lee, Robert B. Dunbar, Peter N. Sedwick, Giacomo R. Ditullio Aug 2011

Iron Limitation Of A Springtime Bacterial And Phytoplankton Community In The Ross Sea: Implications For Vitamin B12 Nutrition, Erin M. Bertrand, Mak A. Saito, Peter A. Lee, Robert B. Dunbar, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B-12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B-12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B-12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early …

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Use Of Sarima Models To Assess Data-Poor Fisheries: A Case Study With A Sciaenid Fishery Off Portugal, Nuno Prista, Norou Diawara, Maria J. Costa, Cynthia M. Jones Jan 2011

Use Of Sarima Models To Assess Data-Poor Fisheries: A Case Study With A Sciaenid Fishery Off Portugal, Nuno Prista, Norou Diawara, Maria J. Costa, Cynthia M. Jones

OES Faculty Publications

Research on assessment and monitoring methods has primarily focused on fisheries with long multivariate data sets. Less research exists on methods applicable to data-poor fisheries with univariate data sets with a small sample size. In this study, we examine the capabilities of seasonal autoregressive integrated moving average (SARIMA) models to fit, forecast, and monitor the landings of such data-poor fisheries. We use a European fishery on meagre (Sciaenidae: Argyrosomus regius), where only a short time series of landings was available to model (n=60 months), as our case-study. We show that despite the limited sample size, a SARIMA model could …

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Anaerobic Oxidation Of Methane And The Stoichiometry Of Remineralization Processes In Continental Margin Sediments, David J. Burdige, Tomoko Kamada Jan 2011

Anaerobic Oxidation Of Methane And The Stoichiometry Of Remineralization Processes In Continental Margin Sediments, David J. Burdige, Tomoko Kamada

OES Faculty Publications

In many coastal and continental margin sediments, pore-water property-property plots yield values of rc:s, the stoichiometric ratio of dissolved inorganic carbon (DIC) produced to sulfate reduced, that are lower than the commonly assumed value of 2. Remineralization of organic matter more reduced than CH2O can cause such observations, as can DIC loss due to authigenic carbonate precipitation. However, through studies of Santa Monica Basin sediments, we have observed that these observations could also be related to the occurrence of anaerobic oxidation of methane (AOM) in sediments. Specifically, using a reactive transport sediment model, we have shown …

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Cascading Migrations And Implications For Vertical Fluxes In Pelagic Ecosystems, Stephen M. Bollens, Gretchen Rollwagen-Bollens, Joel A. Quenette, Alexander B. Bochdansky Jan 2011

Cascading Migrations And Implications For Vertical Fluxes In Pelagic Ecosystems, Stephen M. Bollens, Gretchen Rollwagen-Bollens, Joel A. Quenette, Alexander B. Bochdansky

OES Faculty Publications

Diel vertical migration is widespread across diverse taxa in the world's lakes and seas, yet its biogeochemical consequences are still poorly understood. The biologically mediated vertical flux of material in the ocean (also known as the "biological pump") is a matter of major interest and concern, as it is thought to play an important role in regulating ocean carbon storage, and by extension, the global carbon cycle. Recent studies spanning multiple trophic levels from fish to dinoflagellates have led us to a concept of coupled vertical migrations that we refer to as "cascading migrations". That is, migrations that …

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Modern Dirty Sea Ice Characteristics And Sources: The Role Of Anchor Ice, Dennis A. Darby, Wesley B. Myers, Martin Jakobsson, Ignatius Rigor Jan 2011

Modern Dirty Sea Ice Characteristics And Sources: The Role Of Anchor Ice, Dennis A. Darby, Wesley B. Myers, Martin Jakobsson, Ignatius Rigor

OES Faculty Publications

Extensive dirty ice patches with up to 7 kg m-2 sediment concentrations in layers of up to 10 cm thickness were encountered in 2005 and 2007 in numerous areas across the central Arctic. The Fe grain fingerprint determination of sources for these sampled dirty ice floes indicated both Russian and Canadian sources, with the latter dominating. The presence of benthic shells and sea weeds along with thick layers (2-10 cm) of sediment covering 5-10 m2 indicates an anchor ice entrainment origin as opposed to suspension freezing for some of these floes. The anchor ice origin might explain the …

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Draft Genome Sequence Of Strain Himb100, A Cultured Representative Of The Sar116 Clade Of Marine Alphaproteobacteria, Jana Grote, Cansu Bayindirli, Kristin Bergauer, Paula C. De Moraes, Huan Chen, Lindsay D'Ambrosio, Bethany Edwards, Beatriz Fernandez-Gomez, Mariam Hamisi, Dan Nguyen, Yoshimi M. Rii, Emily Saeck, Charles Schutte, Brittany Widner Jan 2011

Draft Genome Sequence Of Strain Himb100, A Cultured Representative Of The Sar116 Clade Of Marine Alphaproteobacteria, Jana Grote, Cansu Bayindirli, Kristin Bergauer, Paula C. De Moraes, Huan Chen, Lindsay D'Ambrosio, Bethany Edwards, Beatriz Fernandez-Gomez, Mariam Hamisi, Dan Nguyen, Yoshimi M. Rii, Emily Saeck, Charles Schutte, Brittany Widner

OES Faculty Publications

Strain HIMB100 is a planktonic marine bacterium in the class Alphaproteobacteria. This strain is of interest because it is one of the first known isolates from a globally ubiquitous clade of marine bacteria known as SAR116 within the family Rhodospirillaceae. Here we describe preliminary features of the organism, together with the draft genome sequence and annotation. This is the second genome sequence of a member of the SAR116 clade. The 2,458,945 bp genome contains 2,334 protein-coding and 42 RNA gene

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Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz Jan 2011

Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz

OES Faculty Publications

The prevailing paradigm of abrupt climate change holds that rapid shifts associated with the most extreme climate swings of the last glacial cycle were forced by changes in the strength and northward extension of Atlantic Meridional Overturning Circulation (AMOC), resulting in an abrupt reorganization of atmospheric circulation patterns with global teleconnections. To determine the timing of tropical Atlantic atmospheric circulation changes over the past 21 ka BP, we reconstruct high resolution sea surface temperature and δ18OSW (a proxy for surface salinity) records based on Mg/Ca ratios and oxygen isotope measurements in the planktonic foraminifera Globigerinoides ruber from …

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Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero Jan 2011

Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero

OES Faculty Publications

Paleoproxy studies show a strong correlation between tropical climate and high-latitude temperature variability recorded in the Greenland ice cores over the last glacial cycle. In particular, abrupt cooling events in the Greenland Ice Sheet Project II δ18O ice record appear synchronous with a southward migration of the Intertropical Convergence Zone (ITCZ) in the Atlantic, a weakening of the Indian and East Asian monsoon systems, and a strengthening of the South American monsoon system. Because this high-to-low-latitude climate teleconnection significantly alters the tropical hydrologic cycle around the globe, it plays a critical role in regulating global climate on glacial-interglacial …

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Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry Jan 2011

Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry

OES Faculty Publications

The waters passing through the Florida Straits today reflect both the western portion of the wind-driven subtropical gyre and the northward flow of the upper waters which cross the equator, compensating North Atlantic Deep Water export as part of the large-scale Atlantic meridional overturning circulation. It has been postulated from various lines of evidence that the overturning circulation was weaker during the Younger Dryas cold event of the last deglaciation. We show here that the contrast in the oxygen isotopic composition of benthic foraminiferal tests across the Florida Current is reduced during the Younger Dryas. This most likely reflects a …

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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 Jan 2011

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 …

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Clay Mineral Cycles Identified By Diffuse Spectral Reflectance In Quaternary Sediments From The Northwind Ridge: Implications For Glacial-Interglacial Sedimentation Patterns In The Arctic Ocean, Lyanne N. Yurco, Joseph D. Ortiz, Leonid Polyak, Dennis A. Darby, Kevin A. Crawford Aug 2010

Clay Mineral Cycles Identified By Diffuse Spectral Reflectance In Quaternary Sediments From The Northwind Ridge: Implications For Glacial-Interglacial Sedimentation Patterns In The Arctic Ocean, Lyanne N. Yurco, Joseph D. Ortiz, Leonid Polyak, Dennis A. Darby, Kevin A. Crawford

OES Faculty Publications

A Quaternary record of fine-grained sediment composition is used to investigate Arctic Ocean climate variability on glacial-interglacial time scales. Diffuse spectral reflectance data from sediment core P1-92AR-P25 from the Northwind Ridge, north of Alaska, demonstrates cyclic variations in mineralogy. Varimax-rotated R-mode factor analysis of down-core data revealed three major mineralogical assemblages, which were then compared with the content of manganese, a proxy for basin ventilation, and thus glacial-interglacial cycles. Results indicate that factor 1, a smectite + chlorite clay assemblage, was delivered to the core site during interglacials, either by fluvial discharge or sea-ice drift from Siberian rivers or inflow …

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Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige Jan 2010

Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OES Faculty Publications

Development of repeatable and quantitative tools are necessary for determining the abundance and distribution of different types of benthic habitats, detecting changes to these ecosystems, and determining their role in the global carbon cycle. Here we used ocean color remote sensing techniques to map different major groups of primary producers and estimate net primary productivity (NPP) across Great Bahama Bank (GBB). Field investigations on the northern portion of the GBB in 2004 revealed 3 dominant types of benthic primary producers: seagrass, benthic macroalgae, and microalgae attached to sediment. Laboratory measurements of NPP ranged from barely net autotrophic for grapestone sediment …

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On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church Jan 2010

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 …

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Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman Jan 2010

Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman

OES Faculty Publications

The diffuse attenuation coefficient Kᵈ is critical to understand the vertical distribution of underwater downwelling irradiance (Eᵈ). Theoretically Eᵈ is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kᵈ is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Eᵈ(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4%. Field …

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The Widespread Occurrence Of Coupled Carbonate Dissolution/Reprecipitation In Surface Sediments On The Bahamas Bank, David J. Burdige, Xinping Hu, Richard C. Zimmerman Jan 2010

The Widespread Occurrence Of Coupled Carbonate Dissolution/Reprecipitation In Surface Sediments On The Bahamas Bank, David J. Burdige, Xinping Hu, Richard C. Zimmerman

OES Faculty Publications

Using two complimentary approaches (pore water advection/diffusion/reaction modeling and stable isotope mass balance calculations) we show that carbonate dissolution/reprecipitation occurs on early diagenetic time scales across a broad range of sediments on the Great Bahamas Bank. The input of oxygen into the sediments, which strongly controls sediment carbonate dissolution, has two major sources belowground input by seagrasses (that is, seagrass O2 pumping), and permeability-driven advective pore water exchange. The relative importance of these O2 delivery mechanisms depends on both seagrass density, and on how bottom water flow interacts with the seagrass canopy and leads to this advective exchange. …

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The Path To Preservation: Using Proteomics To Decipher The Fate Of Diatom Proteins During Microbial Degradation, Brook L. Nunn, Ying S. Ting, Lars Malmström, Yihsuan S. Tsai, Angela Aquier, David R. Goodlett, H. Rodger Harvey Jan 2010

The Path To Preservation: Using Proteomics To Decipher The Fate Of Diatom Proteins During Microbial Degradation, Brook L. Nunn, Ying S. Ting, Lars Malmström, Yihsuan S. Tsai, Angela Aquier, David R. Goodlett, H. Rodger Harvey

OES Faculty Publications

We drew upon recent advances in tandem mass spectrometry-based proteomic analyses in order to examine the proteins that remain after a diatom bloom enters the stationary phase, precipitates out of the photic zone, and is subjected to microbial degradation over a 23-d period within a controlled laboratory environment. Proteins were identified from tandem mass spectra searched against three different protein databases in order to track proteins from Thalassiosira pseudonana and any potential bacterial contributions. A rapid loss of diatom protein was observed over the incubation period; 75% of the proteins initially identified were not detected after 72 h of exposure …

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Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully Jan 2010

Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully

OES Faculty Publications

Turbulent mixing of salt is examined in a shallow salt wedge estuary with strong fluvial and tidal forcing. A numerical model of the Merrimack River estuary is used to quantify turbulent stress, shear production, and buoyancy flux. Little mixing occurs during flood tides despite strong velocities because bottom boundary layer turbulence is dislocated from stratification elevated in the water column. During ebbs, bottom salinity fronts form at a series of bathymetric transitions. At the fronts, near-bottom velocity and shear stress are low, but shear, stress, and buoyancy flux are elevated at the pycnocline. Internal shear layers provide the dominant source …

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Effect Of The Heterotrophic Dinoflagellate Oxyrrhis Marina And The Copepod Acartia Tonsa On Vertical Carbon Flux In And Around Thin Layers Of The Phytoflagellate Isochrysis Galbana, A. B. Bochdansky, S. M. Bollens, G. C. Rollwagen-Bollens, A. H. Gibson Jan 2010

Effect Of The Heterotrophic Dinoflagellate Oxyrrhis Marina And The Copepod Acartia Tonsa On Vertical Carbon Flux In And Around Thin Layers Of The Phytoflagellate Isochrysis Galbana, A. B. Bochdansky, S. M. Bollens, G. C. Rollwagen-Bollens, A. H. Gibson

OES Faculty Publications

Dynamics of material and energy flow through food webs differ when resources are allocated in patches in comparison to situations in which the same resources are distributed evenly throughout the water column. Thin layers of plankton are special cases of such resource patches. While previous studies have predominantly focused on the response of organisms to these layers, we investigated how 2 types of grazers in turn affect thin layers. In an experimental study with tightly controlled environmental conditions, we monitored the redistribution of particulate organic (POC), dissolved organic (DOC) and inorganic (DIC) carbon from thin layers of Isochrysis galbana. …

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Role Of Macroscopic Particles In Deep-Sea Oxygen Consumption, Alexander B. Bochdansky, Hendrik M. Van Aken, Gerhard J. Herndl Jan 2010

Role Of Macroscopic Particles In Deep-Sea Oxygen Consumption, Alexander B. Bochdansky, Hendrik M. Van Aken, Gerhard J. Herndl

OES Faculty Publications

Macroscopic particles (> 500 µg), including marine snow, large migrating zooplankton, and their fast-sinking fecal pellets, represent primary vehicles of organic carbon flux from the surface to the deep sea. In contrast, freely suspended microscopic particles such as bacteria and protists do not sink, and they contribute the largest portion of metabolism in the upper ocean. In bathy- and abyssopelagic layers of the ocean (2,000-6,000 m), however, microscopic particles may not dominate oxygen consumption. In a section across the tropical Atlantic, we show that macroscopic particle peaks occurred frequently in the deep sea, whereas microscopic particles were barely detectable. In …

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Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan Jan 2010

Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan

OES Faculty Publications

A sensitive flow-injection method with chemiluminescence detection (FI-CL) for the determination of dissolved cobalt in open ocean samples, suitable for shipboard use has been developed. To date, FI methods for dissolved cobalt have been used only in coastal and estuarine waters. Therefore, significant modifications to existing methods were required, including (1) the use of a commercially available iminodiacetate (IDA) resin (Toyopearl AF-chelate 650M) in place of resin immobilized 8-hydroxyquinoline for online preconcentration and matrix removal, (2) the introduction of acidified ammonium acetate (pH 4) as a column-conditioning step before sample loading and rinse steps, and most importantly, (3) UV irradiation …

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Causes Of Tropical Atlantic Paleo-Salinity Variation During Periods Of Reduced Amoc, Xiuquan Wan, Ping Chang, Matthew W. Schmidt Jan 2010

Causes Of Tropical Atlantic Paleo-Salinity Variation During Periods Of Reduced Amoc, Xiuquan Wan, Ping Chang, Matthew W. Schmidt

OES Faculty Publications

During periods of reduced Atlantic meridional overturning circulation (AMOC) associated with a freshening of northern North Atlantic surface water, paleo proxy records indicate a corresponding surface salinity increase over the entire tropical Atlantic. Although latitudinal-shifts in the mean position of the Atlantic Intertropical Convergence Zone (ITCZ) can explain certain features of the paleo salinity reconstructions, this mechanism does not offer an explanation for the reconstructed basin-wide paleo-salinity response to AMOC change. Here, we present new results from general circulation model simulations that suggest the sea surface salinity (SSS) increase in the tropical north Atlantic during periods of weakened AMOC is …

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A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio Jan 2010

A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

We report the distribution of cobalt (Co) in the Ross Sea polynya during austral summer 2005-2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo) was similar to soluble reactive phosphate (PO(4)(3-)), with dCo and PO(4)(3-) showing a significant correlation throughout the water column (r(2) = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from similar to ~ 45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range …

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Variations In Synechococcus Cell Quotas Of Phosphorus, Sulfur, Manganese, Iron, Nickel, And Zinc Within Mesoscale Eddies In The Sargasso Sea, Benjamin S. Twining, Daliangelis Nunez-Milland, Stefan Vogt, Rodney S. Johnson, Peter N. Sedwick Jan 2010

Variations In Synechococcus Cell Quotas Of Phosphorus, Sulfur, Manganese, Iron, Nickel, And Zinc Within Mesoscale Eddies In The Sargasso Sea, Benjamin S. Twining, Daliangelis Nunez-Milland, Stefan Vogt, Rodney S. Johnson, Peter N. Sedwick

OES Faculty Publications

The quotas of P, S, Mn, Fe, Ni, and Zn in individual Synechococcus cells collected from the surface and deep chlorophyll maximum (DCM) layer of three mesoscale eddies in the Sargasso Sea were measured using synchrotron X-ray fluorescence microscopy. Cells in a mode-water eddy had significantly higher P (57 +/- 10 amol) and Mn (28 +/- 7 zmol) cell quotas than cells collected from a cyclone (22 +/- 2 amol and 10 +/- 1 zmol, respectively) or anticyclone (25 +/- 3 amol and 18 +/- 3 zmol, respectively). Conversely, Ni and Zn quotas were significantly higher in the cells from …

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Nutrient Cycles And Marine Microbes In A Co2-Enriched Ocean, David A. Hutchins, Margaret R. Mulholland, Feixue Fu Dec 2009

Nutrient Cycles And Marine Microbes In A Co2-Enriched Ocean, David A. Hutchins, Margaret R. Mulholland, Feixue Fu

OES Faculty Publications

The ocean carbon cycle is tightly linked with the cycles of the major nutrient elements nitrogen, phosphorus, and silicon. It is therefore likely that enrichment of the ocean with anthropogenic CO2 and attendant acidification will have large consequences for marine nutrient biogeochemistry, and for the microbes that mediate many key nutrient transformations. The best available evidence suggests that the nitrogen cycle may respond strongly to higher CO2 through increases in global N2 fixation and possibly denitrification, as well as potential decreases in nitrification. These trends could cause nitrification to become a nitrogen cycle "bottleneck," by increasing the flux of N2 …

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Optics And Remote Sensing Of Bahamian Carbonate Sediment Whitings And Potential Relationship To Wind-Driven Langmuir Circulation, H. M. Dierssen, Richard C. Zimmerman, David J. Burdige Mar 2009

Optics And Remote Sensing Of Bahamian Carbonate Sediment Whitings And Potential Relationship To Wind-Driven Langmuir Circulation, H. M. Dierssen, Richard C. Zimmerman, David J. Burdige

OES Faculty Publications

Regions of milky white seas or "whitings" periodically occur to the west of Andros Island along the Great Bahama Bank where the bottom sediment consists of fine-grained aragonite mud. We present measurements of inherent optical properties within a sediment whiting patch and discuss the potential for monitoring the frequency, extent, and quantity of suspended matter from ocean colour satellite imagery. Sea spectral reflectance measured in situ and remotely from space revealed highly reflective waters elevated across the visible spectrum (i.e., "whitened") with a peak at 490 nm. Particulate backscattering was an order of magnitude higher than that measured at other …

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Potential Export Of Unattached Benthic Macroalgae To The Deep Sea Through Wind Driven Langmuir Circulation, H. M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige Jan 2009

Potential Export Of Unattached Benthic Macroalgae To The Deep Sea Through Wind Driven Langmuir Circulation, H. M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OES Faculty Publications

Carbon export to the deep sea is conventionally attributed to the sinking of open ocean phytoplankton. Here, we report a Langmuir supercell event driven by high winds across the shallow Great Bahama Bank that organized benthic non-attached macroalgae, Colpomenia sp., into visible windrows on the seafloor. Ocean color satellite imagery obtained before and after the windrows revealed a 588 km2 patch that rapidly shifted from highly productive macroalgae to bare sand. We assess a number of possible fates for this macroalgae and contend that this event potentially transported negatively buoyant macroalgae to the deep Tongue of the Ocean …

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Influence Of Irradiance And Iron On The Growth Of Colonial Phaeocystic Antarctica: Implications For Seasonal Bloom Dynamics In The Ross Sea, Antarctica, Nathan S. Garcia, Peter N. Sedwick, Giacomo R. Ditullio Jan 2009

Influence Of Irradiance And Iron On The Growth Of Colonial Phaeocystic Antarctica: Implications For Seasonal Bloom Dynamics In The Ross Sea, Antarctica, Nathan S. Garcia, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

Laboratory culture experiments were used to investigate the growth rate of colonial Phaeocystis anarctica as a function of irradiance and dissolved iron concentration. The experiments were conducted with a P. antarctica strain isolated from the southern Ross Sea, Antarctica, and made use of natural, low-iron (P. antarctica attained an average maximum cell-specific growth rate of 0.37 d-1at an irradiance of 68 μE m-2s-1, above which growth rates decreased to 0.27 d-1 at an irradiance of 314 μE m-2s-1. The dependence of growth rate on ambient dissolved iron concentration was …

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Anthropogenic Osmium In Rain And Snow Reveals Global-Scale Atmospheric Contamination, Cynthia Chen, Peter N. Sedwick, Mukul Sharma Jan 2009

Anthropogenic Osmium In Rain And Snow Reveals Global-Scale Atmospheric Contamination, Cynthia Chen, Peter N. Sedwick, Mukul Sharma

OES Faculty Publications

Osmium is one of the rarer elements in seawater, with typical concentration of ≈10 x 10-15 g g-1 ( 5.3 x 10-14 mol kg-1. The osmium isotope composition (187Os/188Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (≈ 1.3) and mantle/cosmic dust (≈ 0.13). Here, we show that the 187Os/188Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (approximate to 0.2) …

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Cirene Air-Sea Interactions In The Seychelles-Chagos Thermocline Ridge Region, J. Vialard, J. P. Duvel, M. J. Mcphaden, P. Bouruet-Aubertot, B. Ward, E. Key, D. Bourras, R. Weller, P. Minnett, A. Weil Jan 2009

Cirene Air-Sea Interactions In The Seychelles-Chagos Thermocline Ridge Region, J. Vialard, J. P. Duvel, M. J. Mcphaden, P. Bouruet-Aubertot, B. Ward, E. Key, D. Bourras, R. Weller, P. Minnett, A. Weil

OES Faculty Publications

A field experiment in the southwestern Indian Ocean provides new insights into ocean-atmosphere interactions in a key climatic region.

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Thin Layer Formation During Runaway Stratification In The Tidally Dynamic San Francisco Estuary, Alexander B. Bochdansky, Stephen M. Bollens Jan 2009

Thin Layer Formation During Runaway Stratification In The Tidally Dynamic San Francisco Estuary, Alexander B. Bochdansky, Stephen M. Bollens

OES Faculty Publications

During the course of a year, we repeatedly collected high-resolution vertical fluorometer data timed to coincide with a specific state during the tidal cycle. The time (end of the ebb during neap tide) and the location (a deep channel half-way between the Golden Gate and the point of tidally averaged bottom salinity of 2 psu) were chosen with the goal to observe runaway stratification. We consistently found at least one pronounced chlorophyll peak in the water column; however, the vertical location of these peaks varied within three types including surface, bottom and subsurface maxima. Our results showed that heterogeneity of …

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