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Sample records for affect ocean productivity

  1. Iron mobilization in mineral dust: Can anthropogenic SO2 emissions affect ocean productivity?

    NASA Astrophysics Data System (ADS)

    Meskhidze, N.; Chameides, W. L.; Nenes, A.; Chen, G.

    2003-11-01

    For Fe contained in long-range transported aeolian dust to act as a micronutrient for oceanic phytoplankton it must be first dissolved or mobilized. We propose that Fe-mobilization can occur in mineral dust from East Asia by the incorporation of SO2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO2 oxidation. To test this hypothesis, we consider a dust plume that originated from the gobi-deserts and advected over the Pacific Ocean. Data collected over the Yellow Sea confirm that this plume contained high concentrations of dust and SO2. Significant gaseous HNO3 concentrations indicate that the dust particles were acidified (i.e., pH < 2). At these pH's, 1-2% of the Fe contained in a deliquescent mineral dust particle would be mobilized within 3-5 days. These results suggest a possible link between the rate of C-fixation in so-called High-Nitrate-Low-Chlorophyll regions of the Pacific Ocean and SO2 emissions from East Asia.

  2. Light Conditions Affect the Measurement of Oceanic Bacterial Production via Leucine Uptake

    PubMed Central

    Morán, Xosé Anxelu G.; Massana, Ramon; Gasol, Josep M.

    2001-01-01

    The effect of irradiance in the range of 400 to 700 nm or photosynthetically active radiation (PAR) on bacterial heterotrophic production estimated by the incorporation of 3H-leucine (referred to herein as Leu) was investigated in the northwestern Mediterranean Sea and in a coastal North Atlantic site, with Leu uptake rates ranging over 3 orders of magnitude. We performed in situ incubations under natural irradiance levels of Mediterranean samples taken from five depths around solar noon and compared them to incubations in the dark. In two of the three stations large differences were found between light and dark uptake rates for the surfacemost samples, with dark values being on average 133 and 109% higher than in situ ones. Data obtained in coastal North Atlantic waters confirmed that dark enclosure may increase Leu uptake rates more than threefold. To explain these differences, on-board experiments of Leu uptake versus irradiance were performed with Mediterranean samples from depths of 5 and 40 m. Incubations under a gradient of 12 to 1,731 μmol of photons m−2 s−1 evidenced a significant increase in incorporation rates with increasing PAR in most of the experiments, with dark-incubated samples departing from this pattern. These results were not attributed to inhibition of Leu uptake in the light but to enhanced bacterial response when transferred to dark conditions. The ratio of dark to light uptake rates increased as dissolved inorganic nitrogen concentrations decreased, suggesting that bacterial nutrient deficiency was overcome by some process occurring only in the dark bottles. PMID:11525969

  3. East meets West: Differing views of the Aleutian Low's role in affecting Holocene productivity in the Subarctic North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Addison, J. A.; Finney, B. P.; Harada, N.

    2012-12-01

    Modern instrumental and monitoring observations indicate strong multi-decadal changes and spatial heterogeneities affect climate and marine ecosystems in the North Pacific Ocean. Networks of high-resolution paleoclimate archives from this dynamic region are therefore required to describe changes prior to historical records. We present new decadally-resolved marine sediment core data from the Kuril Islands in the Sea of Okhotsk, together with sub-decadal data from the temperate fjords of the Gulf of Alaska (GoAK). These distant sites are located along the western (Kuril) and eastern (GoAK) boundaries of the Subarctic North Pacific Ocean, where micronutrient-rich coastal waters interact with North Pacific high-nutrient-low-chlorophyll (HNLC) waters to drive highly productive marine ecosystems. In the Sea of Okhotsk, a notable increase in opal concentrations (a proxy for past siliceous primary productivity) occurs during the middle Holocene between ~5000 and 6000 yrs ago, while alkenone-based warm season SST proxies either decline or remain relatively constant. A similar middle Holocene increase in opal concentrations is also observed in the GoAK during an interval of declining warm season coastal SAT as inferred from pollen transfer functions [Heusser et al., 1985]. Declining summer solar insolation during the middle Holocene can explain the overall decline in warm-season SST in both the Sea of Okhotsk and the Gulf of Alaska. However, as the increase in opal likely reflects an improvement in North Pacific phytoplankton growing conditions during the spring/summer bloom season, then the opal increase seems unlikely to be related directly to summer solar insolation. We propose a middle Holocene intensification of the Aleutian Low (AL) pressure cell and concomitant changes in North Pacific circulation may be responsible. In both regions, several potential mechanisms related to an intensified AL could result in greater productivity including: (i) increased advection

  4. The Ocean? No Sweat! How the Oceans Affect Temperatures.

    ERIC Educational Resources Information Center

    Current: The Journal of Marine Education, 1986

    1986-01-01

    Presents an activity which helps students investigate how the ocean affects air temperature. Includes temperature data and a map for students to use in plotting and analyzing the temperature ranges of selected cities in Oregon. A supplementary laboratory activity is also offered. (ML)

  5. Will ocean acidification affect marine microbes?

    PubMed Central

    Joint, Ian; Doney, Scott C; Karl, David M

    2011-01-01

    The pH of the surface ocean is changing as a result of increases in atmospheric carbon dioxide (CO2), and there are concerns about potential impacts of lower pH and associated alterations in seawater carbonate chemistry on the biogeochemical processes in the ocean. However, it is important to place these changes within the context of pH in the present-day ocean, which is not constant; it varies systematically with season, depth and along productivity gradients. Yet this natural variability in pH has rarely been considered in assessments of the effect of ocean acidification on marine microbes. Surface pH can change as a consequence of microbial utilization and production of carbon dioxide, and to a lesser extent other microbially mediated processes such as nitrification. Useful comparisons can be made with microbes in other aquatic environments that readily accommodate very large and rapid pH change. For example, in many freshwater lakes, pH changes that are orders of magnitude greater than those projected for the twenty second century oceans can occur over periods of hours. Marine and freshwater assemblages have always experienced variable pH conditions. Therefore, an appropriate null hypothesis may be, until evidence is obtained to the contrary, that major biogeochemical processes in the oceans other than calcification will not be fundamentally different under future higher CO2/lower pH conditions. PMID:20535222

  6. Calibration and Validation for VIIRS Ocean Products

    NASA Astrophysics Data System (ADS)

    Arnone, R.; Davis, C.; May, D.

    2008-12-01

    Satellite data products for ocean color and SST both require precise calibration and validation to meet the continuity of present satellite ocean products. Here we outline the proposed plan for calibration and validation of VIIRS ocean data. The primary ocean color Environmental Data Records (EDRs) are Remote Sensing Reflectances (RSRs); the other EDRs such as chlorophyll are derived from the RSRs. RSRs are derived from the VIIRS Sensor Data Records (SDR) by applying an atmospheric correction that removes the gas absorptions and Rayleigh, aerosol and sea-surface reflectances. Ocean color products require highly accurate calibration and refinement of the sensor calibration using highly accurate in-situ measurements of RSRs (vicarious calibration). Similarly, the SST EDR is strongly dependent on accurate "tuning" algorithm coefficients based on large ocean match-up data sets of buoy and skin temperatures. Ocean products require both a short term and long term monitoring of the sensor "calibration" in order to provide real time ocean products for Navy and NOAA operations. Validation of EDR ocean products requires characterizing the product uncertainty based on match up ocean data from various water and atmospheric types, spanning seasonal and latitudinal variability. Product validation includes matchups with AERONET SeaPRISM above water RSRs combined with in-situ measurements of optical properties, chlorophyll, SST (bulk and skin), and other products. Ocean product validation plans are exploring using an automated network of ocean data for assessing algorithm stability and product uncertainty in order to meet the present need for real-time operational products.

  7. Is the Eocene's climate affected by ocean tides?

    NASA Astrophysics Data System (ADS)

    Weber, Tobias; Thomas, Maik

    2014-05-01

    Global ocean models can generally be divided into Ocean General Circulation and tidal models. Paleoclimate simulations consider dynamics due to the ocean's general, i.e., thermohaline, wind and pressure driven circulation, while tidal dynamics most commonly are neglected due to their strict periodicity and high frequencies. Nevertheless, it could be demonstrated that transport ellipses and energy fluxes are being deformed over shelf areas due to tidal induced friction thus altering ocean circulation and energy fluxes on longer timescales. This makes tides not only an interesting subject of investigation of present-day dynamics, but also of paleo time slices, when both different celestial constellations and geometric shapes of ocean basins affected tidal waves. Using the coupled atmosphere-ocean general circulation model ECHAM5/MPIOM with an integrated tidal module based on luni-solar ephemerides, we simultaneously simulate circulation and tidal dynamics for the Early Eocene (50Ma) and a pre-industrial control run. Major changes in ocean circulation cannot only be observed in shelf areas, but also in the open ocean, for example the Indian and North Atlantic Oceans. Especially the opening of the Tethys Sea alters ocean basin geometry and hereby the dissipation of tidal waves. The southern position of Australia allows resonance between the Indian and Pacific Ocean and leads to high amplitudes in the M2 tide that dominate the Western Pacific and Eastern Indian Oceans. Including tidal dynamics in the ocean model also affects climate by decreasing global mean temperature.

  8. Observations of Ocean Primary Productivity Using MODIS

    NASA Technical Reports Server (NTRS)

    Esaias, Wayne E.; Abbott, Mark R.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Measuring the magnitude and variability of oceanic net primary productivity (NPP) represents a key advancement toward our understanding of the dynamics of marine ecosystems and the role of the ocean in the global carbon cycle. MODIS observations make two new contributions in addition to continuing the bio-optical time series begun with Orbview-2's SeaWiFS sensor. First, MODIS provides weekly estimates of global ocean net primary productivity on weekly and annual time periods, and annual empirical estimates of carbon export production. Second, MODIS provides additional insight into the spatial and temporal variations in photosynthetic efficiency through the direct measurements of solar-stimulated chlorophyll fluorescence. The two different weekly productivity indexes (first developed by Behrenfeld & Falkowski and by Yoder, Ryan and Howard) are used to derive daily productivity as a function of chlorophyll biomass, incident daily surface irradiance, temperature, euphotic depth, and mixed layer depth. Comparisons between these two estimates using both SeaWiFS and MODIS data show significant model differences in spatial distribution after allowance for the different integration depths. Both estimates are strongly dependence on the accuracy of the chlorophyll determination. In addition, an empirical approach is taken on annual scales to estimate global NPP and export production. Estimates of solar stimulated fluorescence efficiency from chlorophyll have been shown to be inversely related to photosynthetic efficiency by Abbott and co-workers. MODIS provides the first global estimates of oceanic chlorophyll fluorescence, providing an important proof of concept. MODIS observations are revealing spatial patterns of fluorescence efficiency which show expected variations with phytoplankton photo-physiological parameters as measured during in-situ surveys. This has opened the way for research into utilizing this information to improve our understanding of oceanic NPP

  9. Evaluation of VIIRS ocean color products

    NASA Astrophysics Data System (ADS)

    Wang, Menghua; Liu, Xiaoming; Jiang, Lide; Son, SeungHyun; Sun, Junqiang; Shi, Wei; Tan, Liqin; Naik, Puneeta; Mikelsons, Karlis; Wang, Xiaolong; Lance, Veronica

    2014-11-01

    The Suomi National Polar-orbiting Partnership (SNPP) was successfully launched on October 28, 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi NPP, which has 22 spectral bands (from visible to infrared) similar to the NASA's Moderate Resolution Imaging Spectroradiometer (MODIS), is a multi-disciplinary sensor providing observations for the Earth's atmosphere, land, and ocean properties. In this paper, we provide some evaluations and assessments of VIIRS ocean color data products, or ocean color Environmental Data Records (EDR), including normalized water-leaving radiance spectra nLw(λ) at VIIRS five spectral bands, chlorophyll-a (Chl-a) concentration, and water diffuse attenuation coefficient at the wavelength of 490 nm Kd(490). Specifically, VIIRS ocean color products derived from the NOAA Multi-Sensor Level-1 to Level-2 (NOAA-MSL12) ocean color data processing system are evaluated and compared with MODIS ocean color products and in situ measurements. MSL12 is now NOAA's official ocean color data processing system for VIIRS. In addition, VIIRS Sensor Data Records (SDR or Level- 1B data) have been evaluated. In particular, VIIRS SDR and ocean color EDR have been compared with a series of in situ data from the Marine Optical Buoy (MOBY) in the waters off Hawaii. A notable discrepancy of global deep water Chl-a derived from MODIS and VIIRS between 2012 and 2013 is observed. This discrepancy is attributed to the SDR (or Level-1B data) calibration issue and particularly related to VIIRS green band at 551 nm. To resolve this calibration issue, we have worked on our own sensor calibration by combining the lunar calibration effect into the current calibration method. The ocean color products derived from our new calibrated SDR in the South Pacific Gyre show that the Chl-a differences between 2012 and 2013 are significantly reduced. Although there are still some issues, our results show that VIIRS is capable of providing high-quality global

  10. LIDAR and acoustics applications to ocean productivity

    NASA Technical Reports Server (NTRS)

    Collins, D. J.

    1982-01-01

    The requirements for the submersible, the instrumentation necessary to perform these measurements, and the optical and acoustical technology required to develop the ocean color scanner instrumentation are described. The development of a second generation ocean color scanner produced the need for coincident in situ scientific measurements which examine the primary productivity of the upper ocean on time and space scales which are large compared to the environmental scales. The vertical and horizontal variability of the biota, including the relationship between chlorophyll and primary productivity, the productivity of zooplankton, and the dynamic interaction between phytoplankton and zooplankton, and between these populations and the physical environment are investigated. A towed submersible will be constructed which accommodates both an underwater LIDAR instrument and a multifrequency sonar.

  11. Global oceanic production of nitrous oxide.

    PubMed

    Freing, Alina; Wallace, Douglas W R; Bange, Hermann W

    2012-05-05

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N(2)O) to estimate the concentration of biologically produced N(2)O and N(2)O production rates in the ocean on a global scale. Our approach to estimate the N(2)O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N(2)O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N(2)O are not taken into account in our study. The largest amount of subsurface N(2)O is produced in the upper 500 m of the water column. The estimated global annual subsurface N(2)O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr(-1). This is in agreement with estimates of the global N(2)O emissions to the atmosphere and indicates that a N(2)O source in the mixed layer is unlikely. The potential future development of the oceanic N(2)O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed.

  12. Global oceanic production of nitrous oxide

    PubMed Central

    Freing, Alina; Wallace, Douglas W. R.; Bange, Hermann W.

    2012-01-01

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N2O) to estimate the concentration of biologically produced N2O and N2O production rates in the ocean on a global scale. Our approach to estimate the N2O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N2O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N2O are not taken into account in our study. The largest amount of subsurface N2O is produced in the upper 500 m of the water column. The estimated global annual subsurface N2O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr−1. This is in agreement with estimates of the global N2O emissions to the atmosphere and indicates that a N2O source in the mixed layer is unlikely. The potential future development of the oceanic N2O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed. PMID:22451110

  13. Sensitivity analysis of an Ocean Carbon Cycle Model in the North Atlantic: an investigation of parameters affecting the air-sea CO2 flux, primary production and export of detritus

    NASA Astrophysics Data System (ADS)

    Scott, V.; Kettle, H.; Merchant, C. J.

    2010-12-01

    The sensitivity of the biological parameters in a nutrient-phytoplankton-zooplankton-detritus (NPZD) model in the calculation of the air-sea CO2 flux, primary production and detrital export is analysed. The NPZD model is the Hadley Centre Ocean Carbon Cycle model (HadOCC) from the UK Met Office, used in the Hadley Centre Coupled Model 3 (HadCM3) and FAst Met Office and Universities Simulator (FAMOUS) GCMs. Here, HadOCC is coupled to the 1-D General Ocean Turbulence Model (GOTM) and forced with European Centre for Medium-Range Weather Forecasting meteorology to undertake a sensitivity analysis of its twenty biological parameters. Analyses are performed at three sites in the EuroSITES European Ocean Observatory Network: the Central Irminger Sea (60° N 40° W), the Porcupine Abyssal Plain (49° N 16° W) and the European Station for Time series in the Ocean Canary Islands (29° N 15° W) to assess variability in parameter sensitivities at different locations in the North Atlantic Ocean. Reasonable changes to the values of key parameters are shown to have a large effect on the calculation of the air-sea CO2 flux, primary production, and export of biological detritus to the deep ocean. Changes in the values of key parameters have a greater effect in more productive regions than in less productive areas. We perform the analysis using one-at-a-time perturbations and using a statistical emulator, and compare results. The most sensitive parameters are generic to many NPZD ocean ecosystem models. The air-sea CO2 flux is most influenced by variation in the parameters that control phytoplankton growth, detrital sinking and carbonate production by phytoplankton (the rain ratio). Primary production is most sensitive to the parameters that define the shape of the photosythesis-irradiance curve. Export production is most sensitive to the parameters that control the rate of detrital sinking and the remineralisation of detritus.

  14. Ensuring Continuity of Coastal Ocean Optical Products

    NASA Astrophysics Data System (ADS)

    Crout, Richard L.; Ladner, Sherwin; Lawson, Adam; Martinolich, Paul; Arnone, Bob; Vandermeulen, Ryan; Bowers, Jennifer

    2015-12-01

    Satellite ocean colour remote sensing evolved rapidly following the 1978 launch of the Color Zone Coastal Scanner (CZCS). Since that launch, the Naval Research Laboratory (NRL) has developed and transitioned tactical ocean optical products (diver visibility, laser penetration depth, chlorophyll concentration, and inherent optical products) from polar-orbiting ocean color sensors to the Naval Oceanographic Office (NAVOCEANO). Beginning with CZCS, NRL exploited the succession of ocean color sensors, including Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging Spectrometer (Aqua MODIS), MEdium Resolution Imaging Spectrometer (MERIS), and the Suomi National Polar-orbiting Partnership Visible Infra Infrared Imager Radiometer Suite (S-NPP VIIRS). Additionally, the geostationary Communication, Ocean, and Meteorological Satellite Geostationary Ocean Color Imager (COMS GOCI) is also being exploited. Future sensors of interest include the Sentinel-3 series Ocean and Land Color Imager (OLCI) and the Joint Polar Satellite System (JPSS) VIIRS. NRL’s Automated Optical Processing System (AOPS) processes ocean color satellite data to provide an operational near-real time depiction of the bio-optical ocean environment. These products are also used for validation of/or assimilation into ocean forecast models and to predict the impact of the environment on Navy coastal operations. NRL contributes to advancements in satellite processing techniques, atmospheric correction for coastal waters, enhanced resolution optical properties using imaging bands, cloud masking, and sensor merging for optimal operational products. Multiple satellites are necessary to provide changing conditions throughout the day allowing for detection of rapid optical temporal and spatial changes due to tides, winds, and river outflow. The Sentinel-3A and -3B OLCIs are critical to Navy coastal operations due to the quality of the data and the morning orbit that complements MODIS Aqua and

  15. Production and fate of transparent exopolymer particles in the ocean

    NASA Astrophysics Data System (ADS)

    Wurl, Oliver; Miller, Lisa; Vagle, Svein

    2011-07-01

    The production and fate of transparent exopolymer particles (TEP) have been investigated in various oceanic regions (tropical, temperate, and polar), from the sea surface microlayer (SML) to the deep ocean. Accumulation of TEP within the mixed layer was observed even in the absence of phytoplankton blooms, indicating abiotic processes are important in TEP production. The abiotic TEP aggregation rates measured in the tropical and temperate North Pacific and the Arctic Ocean averaged between 8 and 12 μmol C L-1 d-1. Depth profiles from under sea ice in the Arctic revealed the highest TEP concentrations, potentially released by sympagic algal activity at the bottom of the sea ice. The aggregation rates in the SML, the interfacial layer between the ocean and atmosphere, were generally enhanced over those in the bulk surface waters by factors of 2 to 30. This finding further strengthens a developing consensus on the gelatinous nature of the SML, which will also affect microbial life, light penetration, and surface wave properties. We present a conceptual model implying that abiotic aggregation is an important factor for TEP production in the ocean, in particular in sea surface microlayers, while consumption by zooplankton and protists recycle TEP, providing a new pool of dissolved precursor material. Overall, TEP is recycled within the water column through heterotrophic grazing and degradation, providing a new pool of TEP precursor materials, while enhanced aggregation rates of TEP in the SML indicates the importance of this thin surface film in the marine carbon cycle.

  16. Processes affecting the oceanic distributions of dissolved calcium and alkalinity

    SciTech Connect

    Shiller, A.M.; Gieskes, J.M.

    1980-05-20

    Recent studies of the CO/sub 2/ system have suggested that chemical processes in addition to the dissolution and precipitation of calcium carbonate affect the oceanic calcium and alkalinity distributions. Calcium and alkalinity data from the North Pacific have been examined both by using the simple physical-chemical model of previous workers and by a study involving the broader oceanographic context of these data. The simple model is shown to be an inadequate basis for these studies. Although a proton flux associated with organic decomposition may affect the alkalinity, previously reported deviations of calcium-alkalinity correlations from expected trends appear to be related to boundary processes that have been neglected rather than to this proton flux. The distribution of calcium in the surface waters of the Pacific Ocean is examined.

  17. New Multiplatform Ocean Surface Wind Product Available

    NASA Astrophysics Data System (ADS)

    Ardizzone, Joseph; Atlas, Robert; Hoffman, Ross N.; Jusem, Juan Carlos; Leidner, S. Mark; Moroni, David F.

    2009-07-01

    A new cross-calibrated, multiplatform (CCMP) ocean surface wind product with wide-ranging research applications in meteorology and oceanography became available at the Physical Oceanography Distributed Active Archive Center (PO.DACC) in May 2009. Data sets at three different levels of processing may be downloaded from http://podaac.jpl.nasa.gov/DATA_CATALOG/ccmpinfo.html. The principal data set, denoted as level 3.0, has global ocean coverage (except for the Arctic Ocean) with 25-kilometer resolution every 6 hours for more than 20 years, beginning in July 1987. Applying an enhanced variational analysis method (VAM) to multiple input data sources creates the level 3.0 data set. The VAM performs quality control and optimally combines wind observations from several individual satellite microwave radiometer and scatterometer sensors along with available conventional ship and buoy wind observations and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses.

  18. Ocean fronts drive marine fishery production and biogeochemical cycling

    PubMed Central

    Woodson, C. Brock; Litvin, Steven Y.

    2015-01-01

    Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy–sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom–up vs. top–down regulation and high productivity in marine ecosystems. PMID:25624488

  19. Ocean fronts drive marine fishery production and biogeochemical cycling.

    PubMed

    Woodson, C Brock; Litvin, Steven Y

    2015-02-10

    Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy-sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom-up vs. top-down regulation and high productivity in marine ecosystems.

  20. Sensitivity analysis of an ocean carbon cycle model in the North Atlantic: an investigation of parameters affecting the air-sea CO2 flux, primary production and export of detritus

    NASA Astrophysics Data System (ADS)

    Scott, V.; Kettle, H.; Merchant, C. J.

    2011-06-01

    The sensitivity of the biological parameters in a nutrient-phytoplankton-zooplankton-detritus (NPZD) model in the calculation of the air-sea CO2 flux, primary production and detrital export is analysed. We explore the effect on these outputs of variation in the values of the twenty parameters that control ocean ecosystem growth in a 1-D formulation of the UK Met Office HadOCC NPZD model used in GCMs. We use and compare the results from one-at-a-time and all-at-a-time perturbations performed at three sites in the EuroSITES European Ocean Observatory Network: the Central Irminger Sea (60° N 40° W), the Porcupine Abyssal Plain (49° N 16° W) and the European Station for Time series in the Ocean Canary Islands (29° N 15° W). Reasonable changes to the values of key parameters are shown to have a large effect on the calculation of the air-sea CO2 flux, primary production, and export of biological detritus to the deep ocean. Changes in the values of key parameters have a greater effect in more productive regions than in less productive areas. The most sensitive parameters are generally found to be those controlling well-established ocean ecosystem parameterisations widely used in many NPZD-type models. The air-sea CO2 flux is most influenced by variation in the parameters that control phytoplankton growth, detrital sinking and carbonate production by phytoplankton (the rain ratio). Primary production is most sensitive to the parameters that define the shape of the photosynthesis-irradiance curve. Export production is most sensitive to the parameters that control the rate of detrital sinking and the remineralisation of detritus.

  1. Parameterization of Oceanic Convection In Primary Production

    NASA Astrophysics Data System (ADS)

    Wehde, Henning

    The influence of Oceanic Convection in Primary Production was investigated in a numerical model study. Lagrangian tracers were introduced to a 2.5 dimensional non- hydrostatic convection model. Model domain is a vertical ocean slice with an isotropic grid size of 5 meters, vanishing gradients normal to the plane and cyclic lateral bound- ary conditions. The horizontal dimension is chosen according to the expected convec- tive aspect ratios that vary between 1 and 3. For each tracer a simple phytoplankton model predicts growth dependent on light conditions. The mean amount of light avail- able for growth for a plankton cell depends on the thickness of the mixed layer and the convective activity. The model was applied to several shelf and open ocean strat- ifications and forced with varying atmospheric conditions to study the sensitivity and to quantify the contact duration and return frequency of plankton into the euphotic zone. The phytoplankton concentration is closely related to the depth of the convec- tively mixed layer. The oceanic convection forms the actual mixed layer depth and was found to heavily influence the contact duration and return frequency of a plank- ton cell into the euphotic zone. Phytoplankton is dispersed by convection in vertical orbit cells. The vertical motion allow for the frequent return of plankton cells to the euphotic zone.

  2. Affective Productions of Mathematical Experience

    ERIC Educational Resources Information Center

    Walshaw, Margaret; Brown, Tony

    2012-01-01

    In underscoring the affective elements of mathematics experience, we work with contemporary readings of the work of Spinoza on the politics of affect, to understand what is included in the cognitive repertoire of the Subject. We draw on those resources to tell a pedagogical tale about the relation between cognition and affect in settings of…

  3. Ocean Surface Topography Data Products and Tools

    NASA Technical Reports Server (NTRS)

    Case, Kelley E.; Bingham, Andrew W.; Berwin, Robert W.; Rigor, Eric M.; Raskin, Robert G.

    2004-01-01

    The Physical Oceanography Distributed Active Archiving Center (PO.DAAC), NASA's primary data center for archiving and distributing oceanographic data, is supporting the Jason and TOPEX/Poseidon satellite tandem missions by providing a variety of data products, tools, and distribution methods to the wider scientific and general community. PO.DAAC has developed several new data products for sea level residual measurements, providing a longterm climate data record from 1992 to the present These products provide compatible measurements of sea level residuals for the entire time series including the tandem TOPEX/Poseidon and Jason mission. Several data distribution tool. are available from NASA PO.DAAC. The Near-Real-Time Image Distribution Server (NEREIDS) provides quicklook browse images and binary data files The PO.DAAC Ocean ESIP Tool (POET) provides interactive, on-tine data subsetting and visualization for several altimetry data products.

  4. Continued increases in Arctic Ocean primary production

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.; van Dijken, Gert L.

    2015-08-01

    Dramatic declines in sea-ice cover in the Arctic Ocean in recent decades have the potential to fundamentally alter marine ecosystems. Here we investigate changes in sea ice between the years 1998 and 2012 at regional and basin scales and how these have impacted rates of phytoplankton net primary production (NPP). Annual NPP increased 30% over the Arctic Ocean during our study period, with the largest increases on the interior shelves and smaller increases on inflow shelves. Increased annual NPP was often, but not always, associated with reduced sea-ice extent and a longer phytoplankton growing season (fewer days of ice cover). Spatial patterns of increased annual NPP suggest that increased nutrient fluxes may also play an important role. Outflow shelves either exhibited no change in annual NPP during our study period or a significant decline, perhaps indicating that nutrients had been consumed by increased NPP farther upstream.

  5. The South Channel Ocean Productivity EXperiment

    NASA Astrophysics Data System (ADS)

    Kenney, Robert D.; Wishner, Karen F.

    The South Channel Ocean Productivity EXperiment (SCOPEX) was a multidisciplinary study of a whale-zooplankton predator-prey system in the southwestern Gulf of Maine, focusing on the oceanographic factors responsible for the development of dense patches of the copepod Calanus finmarchicus, which comprise the major prey resource for right whales ( Eubalaena glacialis). Three non-mutually exclusive hypotheses underlay the study: patch development is due to (1) extremely high in situ primary and secondary productivity; (2) large numbers of Calanus advected into the region and concentrated by hydrographic processes; and/or (3) a behavioral tendency of the copepods themselves to aggregate. The results confirmed the cooccurrence of right whales with high density Calanus patches, and also demonstrated that right whales fed on patches with higher proportions of larger lifestages. The physical oceanographic studies supported the advection hypothesis, possibly augmented by a tendency of Calanus to aggregate, but there was little evidence to support the productivity hypothesis.

  6. Coalition releases declaration for healthy and productive oceans

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-06-01

    Coalition releases declaration for healthy and productive oceans A coalition of 13 countries or federal agencies participating in a new Global Partnership for Oceans (GPO) indicated its support for a “Declaration for Healthy and Productive Oceans to Help Reduce Poverty” on 16 June, just prior to the Rio+20 conference in Rio de Janeiro, Brazil.

  7. Comparative Analysis of GOCI Ocean Color Products

    PubMed Central

    Amin, Ruhul; Lewis, Mark David; Lawson, Adam; Gould, Richard W.; Martinolich, Paul; Li, Rong-Rong; Ladner, Sherwin; Gallegos, Sonia

    2015-01-01

    The Geostationary Ocean Color Imager (GOCI) is the first geostationary ocean color sensor in orbit that provides bio-optical properties from coastal and open waters around the Korean Peninsula at unprecedented temporal resolution. In this study, we compare the normalized water-leaving radiance (nLw) products generated by the Naval Research Laboratory Automated Processing System (APS) with those produced by the stand-alone software package, the GOCI Data Processing System (GDPS), developed by the Korean Ocean Research & Development Institute (KORDI). Both results are then compared to the nLw measured by the above water radiometer at the Ieodo site. This above-water radiometer is part of the Aerosol Robotic NETwork (AeroNET). The results indicate that the APS and GDPS processed nLw correlates well within the same image slot where the coefficient of determination (r2) is higher than 0.84 for all the bands from 412 nm to 745 nm. The agreement between APS and the AeroNET data is higher when compared to the GDPS results. The Root-Mean-Squared-Error (RMSE) between AeroNET and APS data ranges from 0.24 [mW/(cm2srμm)] at 555 nm to 0.52 [mW/(cm2srμm)] at 412 nm while RMSE between AeroNET and GDPS data ranges from 0.47 [mW/(cm2srμm)] at 443 nm to 0.69 [mW/(cm2srμm)] at 490 nm. PMID:26473861

  8. Anthropogenic processing of dust affects the oxygen content of the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nenes, Athanasios; Ito, Taka; Johnson, Matthew; Meskhidze, Nicholas; Valett, Jackie; Deutsch, Curtis

    2015-04-01

    Observations from the last several decades show a significant expansion of the tropical Pacific oxygen minimum zone (OMZ). However, the underlying causes remain elusive, as the currently accepted effects of ocean warming and associated solubility decease cannot fully explain the observed oxygen trend. Here we show that anthropogenic pollution can change the pattern of biological productivity and oxygen trends consistent with observations in the tropics and extratropics. These effects are caused by the mobilization of iron in mineral dust by pollutants, where it is transported and deposited to the HNLC regions of the tropical pacific affecting primary productivity and oxygen consumption by bacterial respiration. In this study, it is shown that pollution-mobilized iron deposited to high latitude oceanic environments can profoundly impact subsurface oxygen and the extent of the OMZ through long-range oceanic transport. Together with the intensification of tropical upwelling since the 1990s associated with natural climate variability, our results can explain the expansion of the OMZ in the tropical Pacific in the late twentieth century. Unlike climate variability, however, anthropogenic pollution likely influences the long-term trends in marine biogeochemistry and further alters regional productivity and subsurface oxygen distributions with profound implications for marine habitats and nitrate inventory of the oceans.

  9. Anthropogenic processing of dust affects the oxygen content of the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nenes, A.; Ito, T.; Johnson, M. S.; Meskhidze, N.; Valett, J.; Deutsch, C. A.

    2014-12-01

    Observations from the last several decades show a significant expansion of the tropical Pacific oxygen minimum zone (OMZ). However, the underlying causes remain elusive, as the currently accepted effects of ocean warming and associated solubility decease cannot fully explain the observed oxygen trend. Here we show that anthropogenic pollution can change the pattern of biological productivity and oxygen trends consistent with observations in the tropics and extratropics. These effects are caused by the mobilization of iron in mineral dust by pollutants, where it is transported and deposited to the HNLC regions of the tropical pacific affecting primary productivity and oxygen consumption by bacterial respiration. In this study, it is shown that pollution-mobilized iron deposited to high latitude oceanic environments can profoundly impact subsurface oxygen and the extent of the OMZ through long-range oceanic transport. Together with the intensification of tropical upwelling since the 1990s associated with natural climate variability, our results can explain the expansion of the OMZ in the tropical Pacific in the late twentieth century. Unlike climate variability, however, anthropogenic pollution likely influences the long-term trends in marine biogeochemistry and further alters regional productivity and subsurface oxygen distributions with profound implications for marine habitats and nitrate inventory of the oceans.

  10. Suomi NPP VIIRS Ocean Color Data Product Early Mission Assessment

    NASA Technical Reports Server (NTRS)

    Turpie, Kevin R.; Robinson, Wayne D.; Franz, Bryan A.; Eplee, Robert E., Jr.; Meister, Gerhard; Fireman, Gwyn F.; Patt, Frederick S.; Barnes, Robert A.; McClain, Charles R.

    2013-01-01

    Following the launch of the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polarorbiting Partnership (NPP) spacecraft, the NASA NPP VIIRS Ocean Science Team (VOST) began an evaluation of ocean color data products to determine whether they could continue the existing NASA ocean color climate data record (CDR). The VOST developed an independent evaluation product based on NASA algorithms with a reprocessing capability. Here we present a preliminary assessment of both the operational ocean color data products and the NASA evaluation data products regarding their applicability to NASA science objectives.

  11. Models for ecological models: Ocean primary productivity

    USGS Publications Warehouse

    Wikle, Christopher K.; Leeds, William B.; Hooten, Mevin B.

    2016-01-01

    The ocean accounts for more than 70% of planet Earth's surface, and it processes are critically important to marine and terrestrial life.  Ocean ecosystems are strongly dependent on the physical state of the ocean (e.g., transports, mixing, upwelling, runoff, and ice dynamics(.  As an example, consider the Coastal Gulf of Alaska (CGOA) region.

  12. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics

    PubMed Central

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-01-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring–summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus–host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus–host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems. PMID:26296067

  13. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics.

    PubMed

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-02-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring-summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus-host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus-host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems.

  14. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Patadia, F.; Hsu, N. C.

    2013-11-01

    The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. The C6 aerosol data set will be created from three separate retrieval algorithms that operate over different surface types. These are the two "Dark Target" (DT) algorithms for retrieving (1) over ocean (dark in visible and longer wavelengths) and (2) over vegetated/dark-soiled land (dark in the visible), plus the "Deep Blue" (DB) algorithm developed originally for retrieving (3) over desert/arid land (bright in the visible). Here, we focus on DT-ocean and DT-land (#1 and #2). We have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, while relaxing the solar zenith angle limit (up to ≤ 84°) to increase poleward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence on the surface reflectance, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. At the same time, we quantified how "upstream" changes to instrument calibration, land/sea masking and cloud masking will also impact the statistics of global AOD, and affect Terra and Aqua differently. For Aqua, all changes will result in reduced

  15. Reconciling fisheries catch and ocean productivity.

    PubMed

    Stock, Charles A; John, Jasmin G; Rykaczewski, Ryan R; Asch, Rebecca G; Cheung, William W L; Dunne, John P; Friedland, Kevin D; Lam, Vicky W Y; Sarmiento, Jorge L; Watson, Reg A

    2017-02-21

    Photosynthesis fuels marine food webs, yet differences in fish catch across globally distributed marine ecosystems far exceed differences in net primary production (NPP). We consider the hypothesis that ecosystem-level variations in pelagic and benthic energy flows from phytoplankton to fish, trophic transfer efficiencies, and fishing effort can quantitatively reconcile this contrast in an energetically consistent manner. To test this hypothesis, we enlist global fish catch data that include previously neglected contributions from small-scale fisheries, a synthesis of global fishing effort, and plankton food web energy flux estimates from a prototype high-resolution global earth system model (ESM). After removing a small number of lightly fished ecosystems, stark interregional differences in fish catch per unit area can be explained (r = 0.79) with an energy-based model that (i) considers dynamic interregional differences in benthic and pelagic energy pathways connecting phytoplankton and fish, (ii) depresses trophic transfer efficiencies in the tropics and, less critically, (iii) associates elevated trophic transfer efficiencies with benthic-predominant systems. Model catch estimates are generally within a factor of 2 of values spanning two orders of magnitude. Climate change projections show that the same macroecological patterns explaining dramatic regional catch differences in the contemporary ocean amplify catch trends, producing changes that may exceed 50% in some regions by the end of the 21st century under high-emissions scenarios. Models failing to resolve these trophodynamic patterns may significantly underestimate regional fisheries catch trends and hinder adaptation to climate change.

  16. Effects of ocean products variability from PSF blurring in NIR band

    NASA Astrophysics Data System (ADS)

    Oh, Eunsong; Ahn, Jae-Hyun; Cho, Seongick; Ahn, Ki-Beom; Park, Young-Je; Kim, Suk-Whan

    2016-10-01

    Development and operational planning for ocean color satellite requires lots of careful consideration of the spatial and radiometric performance, which are represented by modulation transfer function (MTF) and signal-to-noise ratio (SNR) respectively. Those representative values are crucial indicator of sensor performance so that small changes of ocean properties (e.g., remote sensed reflectance (Rrs), surface chlorophyll-a concentrations (Chl-a), and so on) can be quantified and directly related with those values. MTF is affected from a performance of instrument itself and environmental conditions, and its variation leads to change the final products. The goal of this study is to simulate and to analyze the relationship between MTF parameter and ocean product variations, and then to provide a reference for the design of future ocean color sensors. In this study, we used the Geostationary Ocean Color Imager (GOCI) data to generate the simulated atmospheric correction band image. And then Rrs data and ocean products were generated with imagery from two different locations and acquisition times, and we analyzed and compared the statistical results with study area having different characteristics. For ocean products relationships, we notify the linear variation of the absolute percentage difference (APD) according to the changeable MTF value. Especially, Case-II water (turbid water) area shows more sensitive variation than Case-I water (clear water) area. Even though the same area was applied in the simulation, it was 1-2 times higher sensitivity of variation when a specific ocean phenomena such as red tide. The suggested simulation can be confirmed the relationship between blurred NIR band image and ocean products. And statistical results with MTF values were able to help estimating ocean product precision and designing a future mission such as the Geostationary Ocean Color Imager-II (GOCI-II) mission currently being progressed.

  17. Ocean color products from the Korean Geostationary Ocean Color Imager (GOCI).

    PubMed

    Wang, Menghua; Ahn, Jae-Hyun; Jiang, Lide; Shi, Wei; Son, SeungHyun; Park, Young-Je; Ryu, Joo-Hyung

    2013-02-11

    The first geostationary ocean color satellite sensor, Geostationary Ocean Color Imager (GOCI), which is onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS), was successfully launched in June of 2010. GOCI has a local area coverage of the western Pacific region centered at around 36°N and 130°E and covers ~2500 × 2500 km(2). GOCI has eight spectral bands from 412 to 865 nm with an hourly measurement during daytime from 9:00 to 16:00 local time, i.e., eight images per day. In a collaboration between NOAA Center for Satellite Applications and Research (STAR) and Korea Institute of Ocean Science and Technology (KIOST), we have been working on deriving and improving GOCI ocean color products, e.g., normalized water-leaving radiance spectra (nLw(λ)), chlorophyll-a concentration, diffuse attenuation coefficient at the wavelength of 490 nm (Kd(490)), etc. The GOCI-covered ocean region includes one of the world's most turbid and optically complex waters. To improve the GOCI-derived nLw(λ) spectra, a new atmospheric correction algorithm was developed and implemented in the GOCI ocean color data processing. The new algorithm was developed specifically for GOCI-like ocean color data processing for this highly turbid western Pacific region. In this paper, we show GOCI ocean color results from our collaboration effort. From in situ validation analyses, ocean color products derived from the new GOCI ocean color data processing have been significantly improved. Generally, the new GOCI ocean color products have a comparable data quality as those from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua. We show that GOCI-derived ocean color data can provide an effective tool to monitor ocean phenomenon in the region such as tide-induced re-suspension of sediments, diurnal variation of ocean optical and biogeochemical properties, and horizontal advection of river discharge. In particular, we show some examples of ocean

  18. The marketing implications of affective product design.

    PubMed

    Seva, Rosemary R; Duh, Henry Been-Lirn; Helander, Martin G

    2007-11-01

    Emotions are compelling human experiences and product designers can take advantage of this by conceptualizing emotion-engendering products that sell well in the market. This study hypothesized that product attributes influence users' emotions and that the relationship is moderated by the adherence of these product attributes to purchase criteria. It was further hypothesized that the emotional experience of the user influences purchase intention. A laboratory study was conducted to validate the hypotheses using mobile phones as test products. Sixty-two participants were asked to assess eight phones from a display of 10 phones and indicate their emotional experiences after assessment. Results suggest that some product attributes can cause intense emotional experience. The attributes relate to the phone's dimensions and the relationship between these dimensions. The study validated the notion of integrating affect in designing products that convey users' personalities.

  19. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Hsu, N. C.

    2013-01-01

    The twin Moderate Imaging resolution Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an incredible dataset of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there is significant impact on the products and their interpretation. The C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties (1) over ocean (dark in visible and near-IR wavelengths), (2) over vegetated/dark-soiled land (dark in the visible) and (3) over desert/arid land (bright in the visible). Here, we focus on the changes to both "dark target" algorithms (#1 and #2; DT-ocean and DT-land). Affecting both DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, and relaxed the solar zenith angle limit (up to ≤ 84°) to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. All together, the changes to the DT algorithms result in reduced global AOD (by 0.02) over ocean and increased AOD (by 0.01) over land, along with some changes in spatial coverage. Preliminary validation shows that compared to surface-based sunphotometer data, the C6 DT-products should compare at least as well as those from C5. However, at the same time as we

  20. Plio-Pleistocene Ocean Productivity: A Story of Interbasin Symmetry

    NASA Astrophysics Data System (ADS)

    Lawrence, K. T.; Cleaveland, L. C.; Mulligan, A. B.; Herbert, T. D.

    2005-12-01

    The precipitous decline of biological productivity in the high latitude oceans of both the north Pacific and Antarctic synchronous with the intensification of northern hemisphere glaciation (NHG) (2.75 Ma), has previously been attributed to the abrupt onset of ocean stratification in both of these regions. Using the concentration of alkenones, organic compounds exclusively produced by a few species of haptophyte algae, in ocean sediments from the north Atlantic (ODP Site 982), eastern equatorial Pacific (ODP Site 846) and eastern equatorial Atlantic (ODP Site 662) we document the continuous evolution of high latitude and tropical ocean productivity over the past 3.5 Myr. We find that biological productivity in the north Atlantic behaved similarly to that in the high latitude regions of the north Pacific and Antarctic, declining precipitously just after the intensification of NHG. These data suggest that high latitude stratification may have extended into the north Atlantic Ocean, implying that overturning in the north Atlantic after the intensification of NHG may have been significantly weaker than previously proposed. In contrast, productivity in the eastern equatorial Pacific and Atlantic, both low latitude upwelling zones, rose sharply approximately synchronous with the intensification of NHG. We hypothesize that nutrients that were inhibited by the onset of water column stratification from upwelling at high latitudes were instead entrained into the source waters for low latitude upwelling zones feeding the dramatic rise in productivity that occurred in these regions. Our high-resolution (3 kyr) records indicate that on orbital timescales, ocean productivity was anti-correlated to sea surface temperature changes at all sites. In the north Atlantic productivity variations beat at precessional and obliquity periods, while those in the upwelling zones of both the eastern Pacific and Atlantic Oceans beat primarily at obliquity periods. The symmetric behavior of both

  1. Ocean productivity: A personal perspective since the first Liege Colloquium

    NASA Astrophysics Data System (ADS)

    Marra, John F.

    2015-07-01

    I briefly review the changing dominant research agenda in ocean productivity over the time since the first Liege Colloquium, 44 years ago, and coincidentally, about when I started in oceanography. I then consider two lingering issues, the depth of the ocean's productive layer and the dynamics of dissolved organic carbon. These two topics are united through respiration, the former concerning autotrophic respiration, and the latter heterotrophic respiration.

  2. Impacts of VIIRS SDR performance on ocean color products

    NASA Astrophysics Data System (ADS)

    Wang, Menghua; Liu, Xiaoming; Tan, Liqin; Jiang, Lide; Son, SeungHyun; Shi, Wei; Rausch, Kameron; Voss, Kenneth

    2013-09-01

    of the primary goals for the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership is to provide the science and user communities with the data continuity of the Environmental Data Records (EDR) (or Level-2 products) over global oceanic waters for various research and applications, including assessment of climatic and environmental variations. The ocean color EDR is one of the most important products derived from VIIRS. Since ocean color EDR is processed from the upstream Sensor Data Records (SDR) (or Level-1B data), the objective of this study is to evaluate the impact of the SDR on the VIIRS ocean color EDR. The quality of the SDR relies on prelaunch sensor characterizations as well as on-orbit radiometric calibrations, which are used to develop the sensor F-factor lookup tables (F-LUTs). VIIRS F-LUTs derived from solar and lunar calibrations have been used in processing data from the VIIRS Raw Data Records (or Level-0 data) to SDR. In this study, three sets of F-LUTs with different generation schemes have been used to reprocess the SDR and then the ocean color EDR for product evaluations. VIIRS ocean color products are compared with in situ data from the Marine Optical Buoy and products from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua. It is found that the data quality of VIIRS operational ocean color products before 6 February 2012 is poor due to the inappropriate use of the at-launch F-LUTs for the SDR calibration, and that the recently updated VIIRS F-LUTs have significantly improved the SDR and ocean color EDR. Using reprocessed SDR with updated F-LUTs and including vicarious calibration, VIIRS ocean color EDR products are consistent with those from MODIS-Aqua in global deep waters. Although there are still some significant issues with VIIRS ocean color EDR, e.g., poor data quality over coastal regions, our results demonstrate that VIIRS has great potential to provide the

  3. Hydrodynamic Regimes Affect Coral Reef Resilience to Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Teneva, L. T.; Dunbar, R. B.; Koseff, J. R.; Fleischfresser, J. D.; Koweek, D.

    2013-05-01

    Caribbean reefs hold tremendous value as sources of food, income, coastal protection, in addition to their cultural significance. Recently, studies showed that Caribbean reef growth has been surpassed in places by excessive rates of erosion due to climate change. The rates of coral reef response to ocean pH changes and warming and the implications for ecosystem resilience remain largely unknown. One way to investigate the potential structural resilience of reefs to climate change is to measure the physical oceanographic conditions in the area. Determining the hydrodynamic regimes and residence time of water in a particular reef environment is crucial to understanding the rates of future warming and acidification a reef site would experience. Our work on Pacific Islands' hydrodynamics - Central Equatorial Pacific, Great Barrier Reef, and Western Pacific -- would be of interest to Caribbean physical oceanographers and coral reef scientists. We use a combination of Acoustic Doppler Current Profilers, Acoustic Doppler Velocimeters, temperature and salinity sensors, and pressure sensors to characterize reef hydrodynamic regimes. Our work indicates that shallower, more protected reef habitats are characterized by longer residence times, their biological signals are strongly tidally modulated, essentially subjecting such habitats to higher rates of warming and acidification in the future. Reef crest environments and fore reef habitats, on the other hand, are well-mixed with open-ocean water. The hydrodynamic regimes there condition such reef sites to more attenuated temperature and pH ranges, conditions more typical of the open ocean. Our work suggests that investigating the geomorphology and resulting localized hydrodynamics in a reef area can provide insights into the relative rates at which a reef could resist or succumb to impacts of ocean acidification. Such information for different reef islands, in the Pacific or Caribbean basins, could provide helpful insights

  4. Climate-driven trends in contemporary ocean productivity

    NASA Astrophysics Data System (ADS)

    Behrenfeld, Michael J.; O'Malley, Robert T.; Siegel, David A.; McClain, Charles R.; Sarmiento, Jorge L.; Feldman, Gene C.; Milligan, Allen J.; Falkowski, Paul G.; Letelier, Ricardo M.; Boss, Emmanuel S.

    2006-12-01

    Contributing roughly half of the biosphere's net primary production (NPP), photosynthesis by oceanic phytoplankton is a vital link in the cycling of carbon between living and inorganic stocks. Each day, more than a hundred million tons of carbon in the form of CO2 are fixed into organic material by these ubiquitous, microscopic plants of the upper ocean, and each day a similar amount of organic carbon is transferred into marine ecosystems by sinking and grazing. The distribution of phytoplankton biomass and NPP is defined by the availability of light and nutrients (nitrogen, phosphate, iron). These growth-limiting factors are in turn regulated by physical processes of ocean circulation, mixed-layer dynamics, upwelling, atmospheric dust deposition, and the solar cycle. Satellite measurements of ocean colour provide a means of quantifying ocean productivity on a global scale and linking its variability to environmental factors. Here we describe global ocean NPP changes detected from space over the past decade. The period is dominated by an initial increase in NPP of 1,930teragrams of carbon a year (TgCyr-1), followed by a prolonged decrease averaging 190TgCyr-1. These trends are driven by changes occurring in the expansive stratified low-latitude oceans and are tightly coupled to coincident climate variability. This link between the physical environment and ocean biology functions through changes in upper-ocean temperature and stratification, which influence the availability of nutrients for phytoplankton growth. The observed reductions in ocean productivity during the recent post-1999 warming period provide insight on how future climate change can alter marine food webs.

  5. Climate-driven trends in contemporary ocean productivity.

    PubMed

    Behrenfeld, Michael J; O'Malley, Robert T; Siegel, David A; McClain, Charles R; Sarmiento, Jorge L; Feldman, Gene C; Milligan, Allen J; Falkowski, Paul G; Letelier, Ricardo M; Boss, Emmanuel S

    2006-12-07

    Contributing roughly half of the biosphere's net primary production (NPP), photosynthesis by oceanic phytoplankton is a vital link in the cycling of carbon between living and inorganic stocks. Each day, more than a hundred million tons of carbon in the form of CO2 are fixed into organic material by these ubiquitous, microscopic plants of the upper ocean, and each day a similar amount of organic carbon is transferred into marine ecosystems by sinking and grazing. The distribution of phytoplankton biomass and NPP is defined by the availability of light and nutrients (nitrogen, phosphate, iron). These growth-limiting factors are in turn regulated by physical processes of ocean circulation, mixed-layer dynamics, upwelling, atmospheric dust deposition, and the solar cycle. Satellite measurements of ocean colour provide a means of quantifying ocean productivity on a global scale and linking its variability to environmental factors. Here we describe global ocean NPP changes detected from space over the past decade. The period is dominated by an initial increase in NPP of 1,930 teragrams of carbon a year (Tg C yr(-1)), followed by a prolonged decrease averaging 190 Tg C yr(-1). These trends are driven by changes occurring in the expansive stratified low-latitude oceans and are tightly coupled to coincident climate variability. This link between the physical environment and ocean biology functions through changes in upper-ocean temperature and stratification, which influence the availability of nutrients for phytoplankton growth. The observed reductions in ocean productivity during the recent post-1999 warming period provide insight on how future climate change can alter marine food webs.

  6. Ocean glider observations of iceberg-enhanced biological production in the northwestern Weddell Sea

    NASA Astrophysics Data System (ADS)

    Biddle, Louise C.; Kaiser, Jan; Heywood, Karen J.; Thompson, Andrew F.; Jenkins, Adrian

    2015-01-01

    Icebergs affect local biological production around Antarctica. We used an ocean glider to observe the effects of a large iceberg that was advected by the Antarctic Slope Current along the continental slope in the northwestern Weddell Sea in early 2012. The high-resolution glider data reveal a pronounced effect of the iceberg on ocean properties, with oxygen concentrations of (13 ± 4) μmol kg-1 higher than levels in surrounding waters, which are most likely due to positive net community production. This response was confined to three areas of water in the direct vicinity of the iceberg track, each no larger than 2 km2. Our findings suggest that icebergs have an impact on Antarctic production presumably through local micronutrient injections, on a scale smaller than typical satellite observations of biological production in the Southern Ocean.

  7. Isotopic evidence for reduced productivity in the glacial Southern Ocean

    SciTech Connect

    Shemesh, A. ); Macko, S.A. ); Charles, C.D. ); Rau, G.H. )

    1993-10-15

    Records of carbon and nitrogen isotopes in biogenic silica and carbon isotopes in planktonic foraminifera from deep-sea sediment cores from the Southern Ocean reveal that the primary production during the last glacial maximum was lower than Holocene productivity. These observations conflict with the hypothesis that the low atmospheric carbon dioxide concentrations were introduced by an increase in the efficiency of the high-latitude biological pump. Instead, different oceanic sectors may have had high glacial productivity, or alternative mechanisms that do not involve the biological pump must be considered as the primary cause of the low glacial atmospheric carbon dioxide concentrations.

  8. Ocean carbon cycling in the Indian Ocean: 2. Estimates of net community production

    NASA Astrophysics Data System (ADS)

    Bates, Nicholas R.; Pequignet, A. Christine; Sabine, Christopher L.

    2006-09-01

    The spatiotemporal variability of ocean carbon cycling and air-sea CO2 exchange in the Indian Ocean was examined using inorganic carbon data collected as part of the World Ocean Circulation Experiment (WOCE) cruises in 1995. Several carbon mass balance approaches were used to estimate rates of net community production (NCP) in the Indian Ocean. Carbon transports into and out of the Indian Ocean were derived using mass transport estimates of Robbins and Toole (1997) and Schmitz (1996), and transoceanic hydrographic and TCO2 sections at 32°S and across the Indonesian Throughflow. The derived NCP rates of 749 ± 227 to 1572 ± 180 Tg C yr-1 (0.75-1.57 Pg C yr-1) estimated by carbon mass balance were similar to new production rates (1100-1800 Tg C yr-1) determined for the Indian Ocean by a variety of other methods (Louanchi and Najjar, 2000; Gnanadesikan et al., 2002). Changes in carbon inventories of the surface layer were also used to evaluate the spatiotemporal patterns of NCP. Significant NCP occurred in all regions during the Northeast Monsoon and Spring Intermonsoon periods. During the Southwest Monsoon and Fall Intermonsoon periods, the trophic status appears to shift from net autotrophy to net heterotrophy, particularly in the Arabian Sea, Bay of Bengal, and 10°N to 10°S zones.

  9. Ocean Acidification Affects the Phyto-Zoo Plankton Trophic Transfer Efficiency

    PubMed Central

    Cripps, Gemma; Flynn, Kevin J.; Lindeque, Penelope K.

    2016-01-01

    The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios. PMID:27082737

  10. Ocean Acidification Affects the Phyto-Zoo Plankton Trophic Transfer Efficiency.

    PubMed

    Cripps, Gemma; Flynn, Kevin J; Lindeque, Penelope K

    2016-01-01

    The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios.

  11. New production regulates export stoichiometry in the ocean.

    PubMed

    Tamelander, Tobias; Reigstad, Marit; Olli, Kalle; Slagstad, Dag; Wassmann, Paul

    2013-01-01

    The proportion in which carbon and growth-limiting nutrients are exported from the oceans' productive surface layer to the deep sea is a crucial parameter in models of the biological carbon pump. Based on >400 vertical flux observations of particulate organic carbon (POC) and nitrogen (PON) from the European Arctic Ocean we show the common assumption of constant C:N stoichiometry not to be met. Exported POC:PON ratios exceeded the classical Redfield atomic ratio of 6.625 in the entire region, with the largest deviation in the deep Central Arctic Ocean. In this part the mean exported POC:PON ratio of 9.7 (a:a) implies c. 40% higher carbon export compared to Redfield-based estimates. When spatially integrated, the potential POC export in the European Arctic was 10-30% higher than suggested by calculations based on constant POC:PON ratios. We further demonstrate that the exported POC:PON ratio varies regionally in relation to nitrate-based new production over geographical scales that range from the Arctic to the subtropics, being highest in the least productive oligotrophic Central Arctic Ocean and subtropical gyres. Accounting for variations in export stoichiometry among systems of different productivity will improve the ability of models to resolve regional patterns in carbon export and, hence, the oceans' contribution to the global carbon cycle will be predicted more accurately.

  12. Ocean and atmosphere feedbacks affecting AMOC hysteresis in a GCM

    NASA Astrophysics Data System (ADS)

    Jackson, L. C.; Smith, R. S.; Wood, R. A.

    2016-10-01

    Theories suggest that the Atlantic Meridional Overturning Circulation (AMOC) can exhibit a hysteresis where, for a given input of fresh water into the north Atlantic, there are two possible states: one with a strong overturning in the north Atlantic (on) and the other with a reverse Atlantic cell (off). A previous study showed hysteresis of the AMOC for the first time in a coupled general circulation model (Hawkins et al. in Geophys Res Lett. doi: 10.1029/2011GL047208, 2011). In this study we show that the hysteresis found by Hawkins et al. (2011) is sensitive to the method with which the fresh water input is compensated. If this compensation is applied throughout the volume of the global ocean, rather than at the surface, the region of hysteresis is narrower and the off states are very different: when the compensation is applied at the surface, a strong Pacific overturning cell and a strong Atlantic reverse cell develops; when the compensation is applied throughout the volume there is little change in the Pacific and only a weak Atlantic reverse cell develops. We investigate the mechanisms behind the transitions between the on and off states in the two experiments, and find that the difference in hysteresis is due to the different off states. We find that the development of the Pacific overturning cell results in greater atmospheric moisture transport into the North Atlantic, and also is likely responsible for a stronger Atlantic reverse cell. These both act to stabilize the off state of the Atlantic overturning.

  13. Does the Maritime Continent region affect sea level change of the eastern Indian Ocean?

    NASA Astrophysics Data System (ADS)

    Llovel, W.; Lee, T.

    2014-12-01

    The Maritime Continent region, in particular, the Indonesian Sea, regulates the oceanic communication between the Pacific and Indian Oceans. Previous studies suggest that the freshwater transported from the South China Sea to the Indonesian Sea affects the magnitude and structure of the Indonesian throughflow, and the strong tidal mixing in the Indonesian Sea alters the time mean vertical structure of the water mass carried from the Pacific to the Indian Oceans. Sea level changes in the eastern Indian Ocean is known to be affected by those in the northwestern Pacific via coastal Kelvin wave propagation through the Indonesian Sea. However, whether the Maritime Continent region influences sea level changes in the eastern Indian Ocean has not been investigated. In this study, we used Argo floats and satellite altimeter data to study the near decadal change of sea level during the 2005-2013 period. We found that the steric sea level change in eastern Indian Ocean cannot be fully explained by either local forcing or the transmission of steric signal from the western Pacific. This implicates the potential role of the Maritime Continent region in regulating sea level changes in the eastern Indian Ocean.

  14. Decadal Changes in Global Ocean Annual Primary Production

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Conkright, Margarita E.; Behrenfeld, Michael J.; Ginoux, Paul; Casey, Nancy W.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence

  15. Estimating oceanic primary productivity from ocean color remote sensing: A strategic assessment

    NASA Astrophysics Data System (ADS)

    Lee, Zhongping; Marra, John; Perry, Mary Jane; Kahru, Mati

    2015-09-01

    It has long been realized that approaches using satellite ocean-color remote sensing are the only feasible means to quantify primary productivity (PP) adequately for the global ocean. Through decades of dedicated efforts and with the help of various satellite ocean-color missions, great progresses have been achieved in obtaining global PP as well as its spatial and temporal variations. However, there still exist wide differences between satellite estimations and in situ measurements, as well as large discrepancies among results from different models. The reasons for these large differences are many, which include uncertainties in measurements, errors in satellite-derived products, and limitations in the modeling approaches. Unlike previous round-robin reports on PP modeling where the performance of specific models was evaluated and compared, here we try to provide a candid overview of three primary modeling strategies and the nature of present satellite ocean-color products. We further highlight aspects where efforts should be focused in the coming years, with the overarching goal of reducing the gaps between satellite modeling and in situ measurements.

  16. Ocean Processes Driving the Phenology and Productivity of Marine Birds in the California Current System

    NASA Astrophysics Data System (ADS)

    Roth, J. E.; Bradley, R. W.; Warzybok, P.; Abraham, C. L.; Jahncke, J.

    2008-12-01

    We will examine the effects of local ocean conditions and basin-scale patterns of climate variability on phenology and productivity of five species of marine birds to assess how long-term changes in ocean conditions are affecting marine bird populations and to provide insight into how populations may respond to predicted changes in the marine environment under various climate change scenarios. We will focus on Cassin's Auklets, Common Murres, Pigeon Guillemots, Brandt's Cormorants, and Pelagic Cormorants. We will conduct the analyses using an Akaike's Information Criterion approach to model selection, with spring transition date, upwelling strength, and sea surface temperature as measures of local ocean conditions and the Southern Oscillation Index, the Pacific Decadal Oscillation, and the North Pacific Gyre Oscillation as basin-scale measures of climate variability. We will evaluate the relative importance of local versus basin- scale processes on observed trends in seabird breeding phenology and productivity from 1972-2007.

  17. Use of Real Time Satellite Infrared and Ocean Color to Produce Ocean Products

    NASA Astrophysics Data System (ADS)

    Roffer, M. A.; Muller-Karger, F. E.; Westhaver, D.; Gawlikowski, G.; Upton, M.; Hall, C.

    2014-12-01

    Real-time data products derived from infrared and ocean color satellites are useful for several types of users around the world. Highly relevant applications include recreational and commercial fisheries, commercial towing vessel and other maritime and navigation operations, and other scientific and applied marine research. Uses of the data include developing sampling strategies for research programs, tracking of water masses and ocean fronts, optimizing ship routes, evaluating water quality conditions (coastal, estuarine, oceanic), and developing fisheries and essential fish habitat indices. Important considerations for users are data access and delivery mechanisms, and data formats. At this time, the data are being generated in formats increasingly available on mobile computing platforms, and are delivered through popular interfaces including social media (Facebook, Linkedin, Twitter and others), Google Earth and other online Geographical Information Systems, or are simply distributed via subscription by email. We review 30 years of applications and describe how we develop customized products and delivery mechanisms working directly with users. We review benefits and issues of access to government databases (NOAA, NASA, ESA), standard data products, and the conversion to tailored products for our users. We discuss advantages of different product formats and of the platforms used to display and to manipulate the data.

  18. How liability law affects medical productivity.

    PubMed

    Kessler, Daniel P; McClellan, Mark B

    2002-11-01

    Previous research suggests that "direct" reforms to the liability system-reforms designed to reduce the level of compensation to potential claimants-reduce medical expenditures without important consequences for patient health outcomes. We extend this research by identifying the mechanisms through which reforms affect the behavior of health care providers. Although we find that direct reforms improve medical productivity primarily by reducing malpractice claims rates and compensation conditional on a claim, our results suggest that other policies that reduce the time spent and the amount of conflict involved in defending against a claim can also reduce defensive practices substantially. In addition, we find that "malpractice pressure" has a more significant impact on diagnostic rather than therapeutic treatment decisions. Our results provide an empirical foundation for simulating the effects of untried malpractice reforms on health care expenditures and outcomes, based on their predicted effects on the malpractice pressure facing medical providers.

  19. Net production of oxygen in the subtropical ocean.

    PubMed

    Riser, Stephen C; Johnson, Kenneth S

    2008-01-17

    The question of whether the plankton communities in low-nutrient regions of the ocean, comprising 80% of the global ocean surface area, are net producers or consumers of oxygen and fixed carbon is a key uncertainty in the global carbon cycle. Direct measurements in bottle experiments indicate net oxygen consumption in the sunlit zone, whereas geochemical evidence suggests that the upper ocean is a net source of oxygen. One possible resolution to this conflict is that primary production in the gyres is episodic and thus difficult to observe: in this model, oligotrophic regions would be net consumers of oxygen during most of the year, but strong, brief events with high primary production rates might produce enough fixed carbon and dissolved oxygen to yield net production as an average over the annual cycle. Here we examine the balance of oxygen production over three years at sites in the North and South Pacific subtropical gyres using the new technique of oxygen sensors deployed on profiling floats. We find that mixing events during early winter homogenize the upper water column and cause low oxygen concentrations. Oxygen then increases below the mixed layer at a nearly constant rate that is similar to independent measures of net community production. This continuous oxygen increase is consistent with an ecosystem that is a net producer of fixed carbon (net autotrophic) throughout the year, with episodic events not required to sustain positive oxygen production.

  20. Invariable biomass-specific primary production of taxonomically discrete picoeukaryote groups across the Atlantic Ocean.

    PubMed

    Grob, Carolina; Hartmann, Manuela; Zubkov, Mikhail V; Scanlan, Dave J

    2011-12-01

    Oceanic photosynthetic picoeukaryotes (< 3 µm) are responsible for > 40% of total primary production at low latitudes such as the North-Eastern tropical Atlantic. In the world ocean, warmed by climate changes, the expected gradual shift towards smaller primary producers could render the role of photosynthetic picoeukaryotes even more important than they are today. Little is still known, however, about how the taxonomic composition of this highly diverse group affects primary production at the basin scale. Here, we combined flow cytometric cell sorting, NaH¹⁴CO₃ radiotracer incubations and class-specific fluorescence in situ hybridization (FISH) probes to determine cell- and biomass-specific inorganic carbon fixation rates and taxonomic composition of two major photosynthetic picoeukaryote groups on a ∼7500-km-long latitudinal transect across the Atlantic Ocean (Atlantic Meridional Transect, AMT19). We show that even though larger cells have, on average, cell-specific CO₂ uptake rates ∼5 times higher than the smaller ones, the average biomass-specific uptake is statistically similar for both groups. On the other hand, even at a high taxonomic level, i.e. class, the contributions to both groups by Prymnesiophyceae, Chrysophyceae and Pelagophyceae are significantly different (P < 0.001 in all cases). We therefore conclude that these group's carbon fixation rates are independent of the taxonomic composition of photosynthetic picoeukaryotes across the Atlantic Ocean. Because the above applies across different oceanic regions the diversity changes seem to be a secondary factor determining primary production.

  1. Oceanic upwelling and productivity in the eastern tropical Pacific

    SciTech Connect

    Fiedler, P.C.; Philbrick, V. ); Chavez, F.P. )

    1991-12-01

    An oceanographic survey of the eastern tropical Pacific Ocean in August-November 1990 found a productive, nutrient-rich, moderately high-chlorophyll surface layer in two oceanic upwelling regions: the equatorial divergence, especially east of the Galapagos, and the countercurrent divergence out to 105{degree}W, > 1,000 km west of the Costa Rica Dome. Although NO{sub 3} is not depleted in upwelling regions, relationships among nutrient concentrations and temperature in 1986-1988 data from the same area show that NO{sub 3} is the first macronutrient to be depleted in adjacent, less-productive regions. A three-dimensional, two-layer box model of NO{sub 3} flux within and into the euphotic zone gives estimated rates of new production that are {approximately}29% of measured rates of {sup 14}C phytoplankton production. Persistence of excess NO{sub 3} in the euphotic zone exceeds 1 yr under high-nutrient, low-chlorophyll conditions off the equator where weak upwelling, or downwelling, occurs. These results indicate substantial control or limitation of NO{sub 3} utilization and productivity in nutrient-rich oceanic regions of the eastern tropical Pacific.

  2. Carbon-based ocean productivity and phytoplankton physiology from space

    NASA Astrophysics Data System (ADS)

    Behrenfeld, Michael J.; Boss, Emmanuel; Siegel, David A.; Shea, Donald M.

    2005-03-01

    Ocean biogeochemical and ecosystem processes are linked by net primary production (NPP) in the ocean's surface layer, where inorganic carbon is fixed by photosynthetic processes. Determinations of NPP are necessarily a function of phytoplankton biomass and its physiological status, but the estimation of these two terms from space has remained an elusive target. Here we present new satellite ocean color observations of phytoplankton carbon (C) and chlorophyll (Chl) biomass and show that derived Chl:C ratios closely follow anticipated physiological dependencies on light, nutrients, and temperature. With this new information, global estimates of phytoplankton growth rates (μ) and carbon-based NPP are made for the first time. Compared to an earlier chlorophyll-based approach, our carbon-based values are considerably higher in tropical oceans, show greater seasonality at middle and high latitudes, and illustrate important differences in the formation and demise of regional algal blooms. This fusion of emerging concepts from the phycological and remote sensing disciplines has the potential to fundamentally change how we model and observe carbon cycling in the global oceans.

  3. Can ocean acidification affect population dynamics of the barnacle Semibalanus balanoides at its southern range edge?

    PubMed

    Findlay, Helen S; Burrows, Michael T; Kendall, Michael A; Spicer, John I; Widdicombe, Stephen

    2010-10-01

    The global ocean and atmosphere are warming. There is increasing evidence suggesting that, in addition to other environmental factors, climate change is affecting species distributions and local population dynamics. Additionally, as a consequence of the growing levels of atmospheric carbon dioxide (CO2), the oceans are taking up increasing amounts of this CO2, causing ocean pH to decrease (ocean acidification). The relative impacts of ocean acidification on population dynamics have yet to be investigated, despite many studies indicating that there will be at least a sublethal impact on many marine organisms, particularly key calcifying organisms. Using empirical data, we forced a barnacle (Semibalanus balanoides) population model to investigate the relative influence of sea surface temperature (SST) and ocean acidification on a population nearing the southern limit of its geographic distribution. Hindcast models were compared to observational data from Cellar Beach (southwestern United Kingdom). Results indicate that a declining pH trend (-0.0017 unit/yr), indicative of ocean acidification over the past 50 years, does not cause an observable impact on the population abundance relative to changes caused by fluctuations in temperature. Below the critical temperature (here T(crit) = 13.1 degrees C), pH has a more significant affect on population dynamics at this southern range edge. However, above this value, SST has the overriding influence. At lower SST, a decrease in pH (according to the National Bureau of Standards, pHNBs) from 8.2 to 7.8 can significantly decrease the population abundance. The lethal impacts of ocean acidification observed in experiments on early life stages reduce cumulative survival by approximately 25%, which again will significantly alter the population level at this southern limit. Furthermore, forecast predictions from this model suggest that combined acidification and warming cause this local population to die out 10 years earlier than

  4. Limitations on relating ocean surface chlorophyll to productivity

    NASA Technical Reports Server (NTRS)

    Volk, Tyler

    1987-01-01

    An important potential use of ocean color chlorophyll data is to determine other important properties of the marine biosphere, such as primary productivity, new production, and particulate fluxes at spatial scales larger and temporal scales longer than those possible with ground-based observations. Such determinations will likely progress from relatively simple empirical correlations to algorithms that are actually predictive models of ecosystem dynamics. As an example, this paper demonstrates how an empirical correlation between nitrate concentration and new production can be understood by a simple productivity model. Several models are then constructed to examine the functional relationship between total production and surface chlorophyll. The empirical correlation is substantially different than the analogous relation in the model. Understanding the relationship between surface chlorophyll and productivity on a global scale will probably require families of models for various marine ecosystems.

  5. Factors affecting the estimate of primary production from space

    NASA Technical Reports Server (NTRS)

    Balch, W. M.; Byrne, C. F.

    1994-01-01

    Remote sensing of primary production in the euphotic zone has been based mostly on visible-band and water-leaving radiance measured with the coastal zone color scanner. There are some robust, simple relationships for calculating integral production based on surface measurements, but they also require knowledge for photoadaptive parameters such as maximum photosynthesis which currently cannot be obtained from spave. A 17,000-station data set is used to show that space-based estimates of maximum photosynthesis could improve predictions of psi, the water column light utiliztion index, which is an important term in many primary productivity models. Temperature is also examined as a factor for predicting hydrographic structure and primary production. A simple model is used to relate temperature and maximum photosynthesis; the model incorporates (1) the positive relationship between maximum photosynthesis and temperature and (2) the strongly negative relationship between temperature and nitrate in the ocean (which directly affects maximum growth rates via nitrogen limitation). Since these two factors relate to carbon and nitrogen, 'balanced carbon/nitrogen assimilation' was calculated using the Redfield ratio, It is expected that the relationship between maximum balanced carbon assimilation versus temperature is concave-down, with the peak dependent on nitrate uptake kinetics, temperature-nitrate relationships,a nd the carbon chlorophyll ration. These predictions were compared with the sea truth data. The minimum turnover time for nitrate was also calculated using this approach. Lastly, sea surface temperature gradients were used to predict the slope of isotherms (a proxy for the slope of isopycnals in many waters). Sea truth data show that at size scales of several hundred kilometers, surface temperature gradients can provide information on the slope of isotherms in the top 200 m of the water column. This is directly relevant to the supply of nutrients into the surface

  6. Surface Ocean CO2 Atlas (SOCAT) gridded data products

    SciTech Connect

    Sabine, Christopher; Hankin, S.; Koyuk, H; Bakker, D C E; Pfeil, B; Olsen, A; Metzl, N; Fassbender, A; Manke, A; Malczyk, J; Akl, J; Alin, S R; Bellerby, R G J; Borges, A; Boutin, J; Cai, W-J; Chavez, F P; Chen, A; Cosa, C; Feely, R A; Gonzalez-Davila, M; Goyet, C; Hardman-Mountford, N; Heinze, C; Hoppema, M; Hunt, C W; Hydes, D; Ishii, M; Johannessen, T; Key, R M; Kortzinger, A; Landschutzer, P; Lauvset, S K; Lefevre, N; Lourantou, A; Mintrop, L; Miyazaki, C; Murata, A; Nakadate, A; Nakano, Y; Nakaoka, S; Nojiri, Y; et al.

    2013-01-01

    A well documented, publicly available, global data set for surface ocean carbon dioxide (CO2) parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT) project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC). SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968 2007). The SOCAT gridded data is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust regularly spaced fCO2 product with minimal spatial and temporal interpolation which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet, but also contains biases and limitations that the user needs to recognize and address.

  7. Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle.

    PubMed

    Lea-Smith, David J; Biller, Steven J; Davey, Matthew P; Cotton, Charles A R; Perez Sepulveda, Blanca M; Turchyn, Alexandra V; Scanlan, David J; Smith, Alison G; Chisholm, Sallie W; Howe, Christopher J

    2015-11-03

    Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2-540 pg alkanes per mL per day, which translates into a global ocean yield of ∼ 308-771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities.

  8. Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

    PubMed Central

    Lea-Smith, David J.; Biller, Steven J.; Davey, Matthew P.; Cotton, Charles A. R.; Perez Sepulveda, Blanca M.; Turchyn, Alexandra V.; Scanlan, David J.; Smith, Alison G.; Chisholm, Sallie W.; Howe, Christopher J.

    2015-01-01

    Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2–540 pg alkanes per mL per day, which translates into a global ocean yield of ∼308–771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities. PMID:26438854

  9. The significance of nitrification for oceanic new production.

    PubMed

    Yool, Andrew; Martin, Adrian P; Fernández, Camila; Clark, Darren R

    2007-06-21

    The flux of organic material sinking to depth is a major control on the inventory of carbon in the ocean. To first order, the oceanic system is at equilibrium such that what goes down must come up. Because the export flux is difficult to measure directly, it is routinely estimated indirectly by quantifying the amount of phytoplankton growth, or primary production, fuelled by the upward flux of nitrate. To do so it is necessary to take into account other sources of biologically available nitrogen. However, the generation of nitrate by nitrification in surface waters has only recently received attention. Here we perform the first synthesis of open-ocean measurements of the specific rate of surface nitrification and use these to configure a global biogeochemical model to quantify the global role of nitrification. We show that for much of the world ocean a substantial fraction of the nitrate taken up is generated through recent nitrification near the surface. At the global scale, nitrification accounts for about half of the nitrate consumed by growing phytoplankton. A consequence is that many previous attempts to quantify marine carbon export, particularly those based on inappropriate use of the f-ratio (a measure of the efficiency of the 'biological pump'), are significant overestimates.

  10. Mercator Ocean Forecasting Products: Fitting into the Users Needs

    NASA Astrophysics Data System (ADS)

    Baudel, S.; Toumazou, V.

    2006-07-01

    Mercator O cean is a French public initiative aimed to develop ocean forecast op erational systems based on ocean physical models assimilating routin ely r emote sensing (altimetry from Envisat, Jason-1, GFO and Topex/Poseidon), sea surface temperature (in the years to come SMO S sea surf ace salinities) and in situ data. The oth er essen tial and subsequent mission is to allow, to contr ibute and to further operational o ceanography downstream applications. For th at purpose, Mercator Ocean mak es its products available through two different ways: 1. Imag es on the web targeting the g eneral public Every w eek, more than 3000 maps are updated describ ing 3D modelled ocean: now cast, forecast for up to 14 d ays and hind cast, temp erature, salinity, surface current and other ocean par ameters, 5 dep ths from surface to bottom. These images ar e freely av ailab le on the web , excep t the zonal maps younger than 30 day s. For these, the user is expected to fill an on-line form, asking h is/her motiv ations and the use h e/she in tends to do w ith these maps. This con trolled access allows us to dr aw the profile of this aud ience: 370 users ( end of February 2006), represented by the "g eneral public" ( about 40%), resear chers (16%), sailing (13%), studen ts- teachers (10 %), public institutions (8%), in charge of State missions concerning oil dr ift prev ention, environment monitoring, and recreative or professional fishing (7 %). 2. Dig ital files targeting professional u ses The use of d igital files containing the Mer cator outpu ts 3D fields is th e most impor tant criter ia to evaluate the impact of th e usefulness of our products. Mercator has created 'showcase products', summar izing Mercator outpu ts on regular grid s in NetCDF format. Sever al ways are proposed to access these products : FTP and H TTP, in clud ing a LAS/Op endap server, wh ich allows the user to make extraction of a per iod/area/ver tical levels/ocean parameters, and enab ling continuous

  11. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    NASA Astrophysics Data System (ADS)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

  12. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    PubMed Central

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-01-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans. PMID:27982085

  13. Sea spray geoengineering can reduce ocean net primary productivity and carbon uptake

    NASA Astrophysics Data System (ADS)

    Partanen, Antti-Ilari; Keller, David; Korhonen, Hannele; Matthews, Damon

    2016-04-01

    Sea spray geoengineering or marine cloud brightening is one of the proposed methods to deliberately increase planetary albedo and thus counteract climate change. Previous studies have shown that it has potential to significantly alter the global energy balance and reduce impacts on temperature and precipitation. However, its effects on ecosystems have received considerably less attention. Our goal is to assess the effects of sea spray geoengineering on marine biological productivity and global carbon cycle. We use the University of Victoria Earth System Climate Model (UVic ESCM) to simulate the effects of prescribed aerosol forcing from previous simulations with the aerosol-climate model ECHAM-HAMMOZ. In our baseline simulation (GEO), forcing from geoengineering was applied over three persistent stratocumulus regions off the coasts of North America, South America, and South Africa. The global mean forcing was -1 W m-2. Other forcings and emissions were set according to the RCP4.5 scenario. The control run (CTRL) was identical to GEO except that no geoengineering was present. As a more extreme case, we simulated a scenario where forcing from geoengineering was applied over all ocean area (GEO-ALL) giving a global mean forcing of -4.9 W m-2. Geoengineering decreased the global total ocean net primary productivity (NPP) during the first decades, but the effect was insignificant by the end of the 21st century. The decrease was caused by decreased temperature of the ocean and climate system in general, not by the decrease in available sunlight as might have been expected. This was demonstrated by two sensitivity simulations where geoengineering was affecting only either temperature or the light available to marine ecosystems. The simulation GEO-ALL behaves in a different way than GEO: ocean NPP was lower than that in CTRL for the first three decades of geoengineering as in GEO, but then NPP increased over the level in CTRL for the remaining of the simulation. In

  14. A more productive, but different, ocean after mitigation

    NASA Astrophysics Data System (ADS)

    John, Jasmin G.; Stock, Charles A.; Dunne, John P.

    2015-11-01

    Reversibility studies suggest a lagged recovery of global mean sea surface temperatures after mitigation, raising the question of whether a similar lag is likely for marine net primary production (NPP). Here we assess NPP reversibility with a mitigation scenario in which projected Representative Concentration Pathway (RCP) 8.5 forcings are applied out to 2100 and then reversed over the course of the following century in a fully coupled carbon-climate Earth System Model. In contrast to the temperature lag, we find a rapid increase in global mean NPP, including an overshoot to values above contemporary means. The enhanced NPP arises from a transient imbalance between the cooling surface ocean and continued warming in subsurface waters, which weakens upper ocean density gradients, resulting in deeper mixing and enhanced surface nitrate. We also find a marine ecosystem regime shift as persistent silicate depletion results in increased prevalence of large, non-diatom phytoplankton.

  15. Disciplinary reporting affects the interpretation of climate change impacts in global oceans.

    PubMed

    Hauser, Donna D W; Tobin, Elizabeth D; Feifel, Kirsten M; Shah, Vega; Pietri, Diana M

    2016-01-01

    Climate change is affecting marine ecosystems, but different investigative approaches in physical, chemical, and biological disciplines may influence interpretations of climate-driven changes in the ocean. Here, we review the ocean change literature from 2007 to 2012 based on 461 of the most highly cited studies in physical and chemical oceanography and three biological subdisciplines. Using highly cited studies, we focus on research that has shaped recent discourse on climate-driven ocean change. Our review identified significant differences in spatial and temporal scales of investigation among disciplines. Physical/chemical studies had a median duration of 29 years (n = 150) and covered the greatest study areas (median 1.41 × 10(7) km(2) , n = 148). Few biological studies were conducted over similar spatial and temporal scales (median 8 years, n = 215; median 302 km(2) , n = 196), suggesting a more limited ability to separate climate-related responses from natural variability. We linked physical/chemical and biological disciplines by tracking studies examining biological responses to changing ocean conditions. Of the 545 biological responses recorded, a single physical or chemical stressor was usually implicated as the cause (59%), with temperature as the most common primary stressor (44%). The most frequently studied biological responses were changes in physiology (31%) and population abundance (30%). Differences in disciplinary studies, as identified in this review, can ultimately influence how researchers interpret climate-related impacts in marine systems. We identified research gaps and the need for more discourse in (1) the Indian and other Southern Hemisphere ocean basins; (2) research themes such as archaea, bacteria, viruses, mangroves, turtles, and ocean acidification; (3) physical and chemical stressors such as dissolved oxygen, salinity, and upwelling; and (4) adaptive responses of marine organisms to climate-driven ocean change. Our findings reveal

  16. Photochemical Production of Alkyl Nitrates in the Tropical Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Dahl, E. E.; Yvon-Lewis, S. A.; Saltzman, E. S.

    2005-12-01

    Alkyl nitrates are important to the tropospheric NOx/ozone cycle because they represent a significant fraction of the reactive nitrogen (NOy). Previous work has shown that there is an oceanic source of alkyl nitrates. A photochemical mechanism for the formation of alkyl nitrates in seawater has been proposed. This mechanism involves the reaction of ROO and NO, where ROO is an alkyl peroxy radical. ROO and NO radicals in seawater are derived from the photolysis of DOM and nitrite, respectively. In this study, the photochemical production of low molecular weight alkyl nitrates (C1-C3) was observed in shipboard incubation experiments in the tropical Pacific during the PHASE 1 cruise. Seawater samples from several regions, including high and low-chlorophyll areas, were collected and incubated. Alkyl nitrate production rates as high as 2 nM/hour were observed. The production rate of alkyl nitrates was clearly dependent upon the initial concentration of nitrite, most likely as the source for NO radicals. While the magnitude of production varied between sample locations, the ratios of the production rates of the various alkyl nitrates remained relatively constant. The observed production ratios of methyl, ethyl, isopropyl, and n-propyl nitrate were 5.9:1.0:0.1:0.2. These ratios presumably reflect the speciation of peroxy radicals formed in seawater, and the yield of alkyl nitrates from the ROO+NO reaction. The observed production rate ratios are similar to the concentration ratios of alkyl nitrates observed in ambient seawater and the overlying atmosphere during the study. A comparison of the measured production rates and the observed concentrations, suggests that photochemically produced alkyl nitrates are a major source of atmospheric alkyl nitrates in the surface ocean and marine atmosphere.

  17. Seabird guano enhances phytoplankton production in the Southern Ocean.

    NASA Astrophysics Data System (ADS)

    Shatova, Olga; Wing, Stephen; Hoffmann, Linn; Jack, Lucy; Gault-Ringold, Melanie

    2015-04-01

    Great congregations of seabirds in sub-Antarctic and Antarctic coastal areas result in delivery of nutrient-rich guano to marine ecosystems that potentially enhances productivity and supports biodiversity in the region. Guano-derived bio-available micronutrients and macronutrients might be utilized by marine phytoplankton for photosynthetic production, however, mechanisms and significance of guano fertilization in the Southern Ocean are largely understudied. Over austral summers of 2012 and 2013 we performed a series of guano-enrichment phytoplankton incubation experiments with water samples collected from three different water masses in the Southern Ocean: Antarctic waters of the Ross sea and sub-Antarctic waters offshore the Otago Peninsula, both showing iron limitation of phytoplankton productivity in summer, and in the subtropical frontal zone offshore from the Snares Islands, which is generally micronutrient-repleted. Samples were enriched with known concentrations of guano-derived nutrients. Phytoplankton biomass increased significantly in guano-treated samples during all three incubation experiments (7-10 fold increase), while remained low in control samples. This response indicates that seabird guano provides nutrients that limit primary production in the Southern Ocean and that these nutrients are readily taken up by phytoplankton. Guano additions were compared to Fe and Macronutrient treatments (both added in quantities similar to those in the guano treatment). Phytoplankton biomass increased significantly in response to the Macronutrient treatment in the subtropical frontal zone, however, the response had a smaller magnitude compared to the guano treatment (2.8 µgL-1 vs 5.2 µgL-1) ; there was no significant effect of Fe on phytoplankton growth. This suggests the potential importance of synergistic effects of nutrients in guano. Incubation with sub-Antarctic waters showed that Fe and Macronutrients might be equally important for enhancement of

  18. Silent oceans: ocean acidification impoverishes natural soundscapes by altering sound production of the world's noisiest marine invertebrate.

    PubMed

    Rossi, Tullio; Connell, Sean D; Nagelkerken, Ivan

    2016-03-16

    Soundscapes are multidimensional spaces that carry meaningful information for many species about the location and quality of nearby and distant resources. Because soundscapes are the sum of the acoustic signals produced by individual organisms and their interactions, they can be used as a proxy for the condition of whole ecosystems and their occupants. Ocean acidification resulting from anthropogenic CO2 emissions is known to have profound effects on marine life. However, despite the increasingly recognized ecological importance of soundscapes, there is no empirical test of whether ocean acidification can affect biological sound production. Using field recordings obtained from three geographically separated natural CO2 vents, we show that forecasted end-of-century ocean acidification conditions can profoundly reduce the biological sound level and frequency of snapping shrimp snaps. Snapping shrimp were among the noisiest marine organisms and the suppression of their sound production at vents was responsible for the vast majority of the soundscape alteration observed. To assess mechanisms that could account for these observations, we tested whether long-term exposure (two to three months) to elevated CO2 induced a similar reduction in the snapping behaviour (loudness and frequency) of snapping shrimp. The results indicated that the soniferous behaviour of these animals was substantially reduced in both frequency (snaps per minute) and sound level of snaps produced. As coastal marine soundscapes are dominated by biological sounds produced by snapping shrimp, the observed suppression of this component of soundscapes could have important and possibly pervasive ecological consequences for organisms that use soundscapes as a source of information. This trend towards silence could be of particular importance for those species whose larval stages use sound for orientation towards settlement habitats.

  19. Silent oceans: ocean acidification impoverishes natural soundscapes by altering sound production of the world's noisiest marine invertebrate

    PubMed Central

    Rossi, Tullio; Connell, Sean D.; Nagelkerken, Ivan

    2016-01-01

    Soundscapes are multidimensional spaces that carry meaningful information for many species about the location and quality of nearby and distant resources. Because soundscapes are the sum of the acoustic signals produced by individual organisms and their interactions, they can be used as a proxy for the condition of whole ecosystems and their occupants. Ocean acidification resulting from anthropogenic CO2 emissions is known to have profound effects on marine life. However, despite the increasingly recognized ecological importance of soundscapes, there is no empirical test of whether ocean acidification can affect biological sound production. Using field recordings obtained from three geographically separated natural CO2 vents, we show that forecasted end-of-century ocean acidification conditions can profoundly reduce the biological sound level and frequency of snapping shrimp snaps. Snapping shrimp were among the noisiest marine organisms and the suppression of their sound production at vents was responsible for the vast majority of the soundscape alteration observed. To assess mechanisms that could account for these observations, we tested whether long-term exposure (two to three months) to elevated CO2 induced a similar reduction in the snapping behaviour (loudness and frequency) of snapping shrimp. The results indicated that the soniferous behaviour of these animals was substantially reduced in both frequency (snaps per minute) and sound level of snaps produced. As coastal marine soundscapes are dominated by biological sounds produced by snapping shrimp, the observed suppression of this component of soundscapes could have important and possibly pervasive ecological consequences for organisms that use soundscapes as a source of information. This trend towards silence could be of particular importance for those species whose larval stages use sound for orientation towards settlement habitats. PMID:26984624

  20. Southern Ocean Seasonal Net Production from Satellite, Atmosphere, and Ocean Data Sets

    NASA Technical Reports Server (NTRS)

    Keeling, Ralph F.; Campbell, J. (Technical Monitor)

    2002-01-01

    A new climatology of monthly air-sea O2 flux was developed using the net air-sea heat flux as a template for spatial and temporal interpolation of sparse hydrographic data. The climatology improves upon the previous climatology of Najjar and Keeling in the Southern Hemisphere, where the heat-based approach helps to overcome limitations due to sparse data coverage. The climatology is used to make comparisons with productivity derived from CZCS images. The climatology is also used in support of an investigation of the plausible impact of recent global warming an oceanic O2 inventories.

  1. Ocean acidification affects iron speciation during a coastal seawater mesocosm experiment

    NASA Astrophysics Data System (ADS)

    Breitbarth, E.; Bellerby, R. J.; Neill, C. C.; Ardelan, M. V.; Meyerhöfer, M.; Zöllner, E.; Croot, P. L.; Riebesell, U.

    2010-03-01

    Rising atmospheric CO2 is acidifying the surface ocean, a process which is expected to greatly influence the chemistry and biology of the future ocean. Following the development of iron-replete phytoplankton blooms in a coastal mesocosm experiment at 350, 700, and 1050 μatm pCO2, we observed significant increases in dissolved iron concentrations, Fe(II) concentrations, and Fe(II) half-life times during and after the peak of blooms in response to CO2 enrichment and concomitant lowering of pH, suggesting increased iron bioavailability. If applicable to the open ocean this may provide a negative feedback mechanism to the rising atmospheric CO2 by stimulating marine primary production.

  2. Parameters affecting solvent production by Clostridium pasteurianum

    SciTech Connect

    Dabrock, B.; Bahl, H.; Gottschalk, G. )

    1992-04-01

    The effect of pH, growth rate, phosphate and iron limitation, carbon monoxide, and carbon source on product formation by Clostridium pasteurianum was determined. Under phosphate limitation, glucose was fermented almost exclusively to acetate and butyrate independently of the pH and growth rate. Iron limitation caused lactate production (38 mol/100 mol) from glucose in batch and continuous culture. At 15% (vol/vol) carbon monoxide in the atmosphere, glucose was fermented to ethanol (24 mol/100 mol), lactate (32 mol/100 mol), and butanol (36 mol/100 mol) in addition to the usual products, acetate (38 mol/100 mol) and butyrate (17 mol/100 mol). During glycerol fermentation, a completely different product pattern was found. In continuous culture under phosphate limitation, acetate and butyrate were produced only in trace amounts, whereas ethanol (30 mol/10 mol), butanol (18 mol/100 mol), and 1,3-propanediol (18 mol/100 mol) were the major products. Under iron limitation, the ratio of these products could be changed in favor of 1,3-propanediol (34 mol/100 mol). In addition, lactate was produced in significant amounts (25 mol/100 mol). The tolerance of C. pasteurianum to glycerol was remarkably high; growth was not inhibited by glycerol concentrations up to 17% (wt/vol). Increasing glycerol concentrations favored the production of 1,3-propanediol.

  3. The Making of a Productivity Hotspot in the Coastal Ocean

    PubMed Central

    Wingfield, Dana K.; Peckham, S. Hoyt; Foley, David G.; Palacios, Daniel M.; Lavaniegos, Bertha E.; Durazo, Reginaldo; Nichols, Wallace J.; Croll, Donald A.; Bograd, Steven J.

    2011-01-01

    Background Highly productive hotspots in the ocean often occur where complex physical forcing mechanisms lead to aggregation of primary and secondary producers. Understanding how hotspots persist, however, requires combining knowledge of the spatio-temporal linkages between geomorphology, physical forcing, and biological responses with the physiological requirements and movement of top predators. Methodology/Principal Findings Here we integrate remotely sensed oceanography, ship surveys, and satellite telemetry to show how local geomorphology interacts with physical forcing to create a region with locally enhanced upwelling and an adjacent upwelling shadow that promotes retentive circulation, enhanced year-round primary production, and prey aggregation. These conditions provide an area within the upwelling shadow where physiologically optimal water temperatures can be found adjacent to a region of enhanced prey availability, resulting in a foraging hotspot for loggerhead sea turtles (Caretta caretta) off the Baja California peninsula, Mexico. Significance/Conclusions We have identified the set of conditions that lead to a persistent top predator hotspot, which increases our understanding of how highly migratory species exploit productive regions of the ocean. These results will aid in the development of spatially and environmentally explicit management strategies for marine species of conservation concern. PMID:22132156

  4. Declining Global Per Capita Agricultural Production and Warming Oceans Threaten Food Security

    NASA Technical Reports Server (NTRS)

    Funk, Chris C.; Brown, Molly E.

    2009-01-01

    Despite accelerating globalization, most people still eat food that was grown locally. Developing countries with weak purchasing power tend to import as little food as possible from global markets, suffering consumption deficits during times of high prices or production declines. Local agricultural production, therefore, is critical to both food security and economic development among the rural poor. The level of local agricultural production, in turn, will be controlled by the amount and quality of arable land, the amount and quality of agricultural inputs (fertilizer, seeds, pesticides, etc.), as well as farm-related technology, practices, and policies. In this paper we discuss several emerging threats to global and regional food security, including declining yield gains that are failing to keep up with population increases, and warming in the tropical Indian Ocean and its impact on rainfall. If yields continue to grow more slowly than per capita harvested area, parts of Africa, Asia, and Central and Southern America will experience substantial declines in per capita cereal production. Global per capita cereal production will potentially decline by 14 percent between 2008 and 2030. Climate change is likely to further affect food production, particularly in regions that have very low yields due to lack of technology. Drought, caused by anthropogenic warming in the Indian and Pacific Oceans, may also reduce 21 st century food availability by disrupting Indian Ocean moisture transports and tilting the 21 st century climate toward a more El Nino-like state. The impacts of these circulation changes over Asia remain uncertain. For Africa, however, Indian Ocean warming appears to have already reduced main growing season rainfall along the eastern edge of tropical Africa, from southern Somalia to northern parts of the Republic of South Africa. Through a combination of quantitative modeling of food balances and an examination of climate change, we present an analysis of

  5. Productivity of the glacial ocean: Discussion of the iron hypothesis

    SciTech Connect

    Berger, W.H. ); Wefer, G. )

    1991-12-01

    An increase in the productivity of the glacial-age Southern Ocean has been postulated to explain the decrease in pCO{sub 2} of the atmosphere observed in ice cores. A plausible mechanism has been proposed elsewhere that productivity is limited by the availability of Fe in this region and that the greater supply of eolian dust during glacial time removed this limit. Recently published evidence from cores from the Southern Ocean suggests that in fact there was no change in productivity in the assumed manner. Glacial-age productivity was indeed greatly increased in the equatorial Pacific and in the eastern boundary upwelling systems. The cause, presumably, was the mechanical action of glacial-age winds rather than a greater supply of Fe. However, a role of increased supply of micronutrients from the continents in the increase of equatorial productivity during glacial time cannot be excluded. Such enhancement from increased supply of dust would have the interesting corollary of more efficient export transfer to depth, possibly contributing to nutrient depletion in glacial-age, deep intermediate waters. There is some indication, as well, of a general decrease in nutrient content in the tropical thermocline in the western Pacific during the last several million years, a depletion that may have been fostered by increasing supply of dust from emerging Asian highlands. Alternative explanations are available. The case for Fe as a major modifier of productivity and biogenic sedimentation on geological time scales cannot be made in the absence of criteria diagnostic for Fe supply as opposed to stirring and upwelling.

  6. Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent.

    PubMed

    Nicol, S; Pauly, T; Bindoff, N L; Wright, S; Thiele, D; Hosie, G W; Strutton, P G; Woehler, E

    2000-08-03

    Sea ice and oceanic boundaries have a dominant effect in structuring Antarctic marine ecosystems. Satellite imagery and historical data have identified the southern boundary of the Antarctic Circumpolar Current as a site of enhanced biological productivity. Meso-scale surveys off the Antarctic peninsula have related the abundances of Antarctic krill (Euphausia superba) and salps (Salpa thompsoni) to inter-annual variations in sea-ice extent. Here we have examined the ecosystem structure and oceanography spanning 3,500 km of the east Antarctic coastline, linking the scales of local surveys and global observations. Between 80 degrees and 150 degrees E there is a threefold variation in the extent of annual sea-ice cover, enabling us to examine the regional effects of sea ice and ocean circulation on biological productivity. Phytoplankton, primary productivity, Antarctic krill, whales and seabirds were concentrated where winter sea-ice extent is maximal, whereas salps were located where the sea-ice extent is minimal. We found enhanced biological activity south of the southern boundary of the Antarctic Circumpolar Current rather than in association with it. We propose that along this coastline ocean circulation determines both the sea-ice conditions and the level of biological productivity at all trophic levels.

  7. Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota.

    PubMed

    Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe

    2014-10-01

    Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed.

  8. Uranium Stable Isotopes: A Proxy For Productivity Or Ocean Oxygenation?

    NASA Astrophysics Data System (ADS)

    Severmann, S.

    2015-12-01

    Uranium elemental abundances in sediments have traditionally been used to reconstruct primary productivity and carbon flux in the ocean. 238U/235U isotope compositions, in contrast, are currently understood to reflect the extent of bottom water anoxia in the ocean. A review of our current understanding of authigenic U enrichment mechanism into reducing sediments suggests that a revision of this interpretation is warranted. Specifically, the current interpretation of U isotope effects in suboxic vs. anoxic deposits has not taken into account the well-documented linear relationship with organic C burial rates. Although organic C rain rates (i.e., surface productivity) and bottom water oxygenation are clearly related, distinction between these two environmental controls is conceptually important as it relates to the mechanism of enhanced C burial and ultimately the strength of the biological pump. Here we will review new and existing data to test the hypothesis that the isotope composition of authigenic U in reducing sediments are best described by their relationship with parameters related to organic carbon delivery and burial, rather than bottom water oxygen concentration.

  9. Strategies for gas production from oceanic Class 3 hydrateaccumulations

    SciTech Connect

    Moridis, George J.; Reagan, Matthew T.

    2007-05-01

    Gas hydrates are solid crystalline compounds in which gasmolecules are lodged within the lattices of ice crystals. Vast amounts ofCH4 are trapped in gas hydrates, and a significant effort has recentlybegun to evaluate hydrate deposits as a potential energy source. Class 3hydrate deposits are characterized by an isolated Hydrate-Bearing Layer(HBL) that is not in contact with any hydrate-free zone of mobile fluids.The base of the HBL in Class 3 deposits may occur within or at the edgeof the zone of thermodynamic hydrate stability.In this numerical study oflong-term gas production from typical representatives of unfracturedClass 3 deposits, we determine that simple thermal stimulation appears tobe a slow and inefficient production method. Electrical heating and warmwater injection result in very low production rates (4 and 12 MSCFD,respectively) that are orders of magnitude lower than generallyacceptable standards of commercial viability of gas production fromoceanic reservoirs. However, production from depressurization-baseddissociation based on a constant well pressure appears to be a promisingapproach even in deposits characterized by high hydrate saturations. Thisapproach allows the production of very large volumes ofhydrate-originating gas at high rates (>15 MMSCFD, with a long-termaverage of about 8.1 MMSCFD for the reference case) for long times usingconventional technology. Gas production from hydrates is accompanied by asignificant production of water. However, unlike conventional gasreservoirs, the water production rate declines with time. The lowsalinity of the produced water may require care in its disposal. Becauseof the overwhelming advantage of depressurization-based methods, thesensitivity analysis was not extendedto thermal stimulation methods. Thesimulation results indicate that depressurization-induced gas productionfrom oceanic Class 3 deposits increases (and the corresponding waterto-gas ratio decreases) with increasing hydrate temperature

  10. Assessment of uncertainties of ocean color parameters for the ocean Carbon-based Productivity Model

    NASA Astrophysics Data System (ADS)

    Sheng, M. A.; Xiaofeng, Yang; Zui, Tao; Ziwei, Li; Xuan, Zhou

    2014-03-01

    With the developments of ocean color remote sensing technology, some ocean color parameters can be derived by satellite globally. These terms, including chlorophyll concentration (Chl), particulate backscattering coefficients (bbp), photosynthetically available radiation (PAR), have been proved to be related to NPP of phytoplankton. Based on these parameters with other auxiliary data, a carbon-based productivity model (CbPM) had been developed. The model derives phytoplankton carbon(C) from bbp and utilizes the ratios of C and Chl to describe the phytoplankton growth rates (μ) which has physiological dependencies on light (through variations in PAR), nutrients, and temperature. This paper indicated how the uncertainties in satellite derived parameters (Chl, bbp and PAR) propagated through the CbPM using Monte Carlo method. Comparisons on the individual contributor to the random uncertainty in NPP between these input items were discussed. The analysis results showed that among the three parameters, the biggest contribution to the uncertainty in the model output came from Chl. Therefore, improvements in the accuracy of Chl would have the largest potential to improve the ability of CbPM in estimating NPP of phytoplankton.

  11. Evidence for deep-water production in the North Pacific Ocean during the early Cenozoic warm interval.

    PubMed

    Thomas, Deborah J

    2004-07-01

    The deep-ocean circulation is responsible for a significant component of global heat transport. In the present mode of circulation, deep waters form in the North Atlantic and Southern oceans where surface water becomes sufficiently cold and dense to sink. Polar temperatures during the warmest climatic interval of the Cenozoic era (approximately 65 to 40 million years (Myr) ago) were significantly warmer than today, and this may have been a consequence of enhanced oceanic heat transport. However, understanding the relationship between deep-ocean circulation and ancient climate is complicated by differences in oceanic gateways, which affect where deep waters form and how they circulate. Here I report records of neodymium isotopes from two cores in the Pacific Ocean that indicate a shift in deep-water production from the Southern Ocean to the North Pacific approximately 65 Myr ago. The source of deep waters reverted back to the Southern Ocean 40 Myr ago. The relative timing of changes in the neodymium and oxygen isotope records indicates that changes in Cenozoic deep-water circulation patterns were the consequence, not the cause, of extreme Cenozoic warmth.

  12. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-12-01

    Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from -15.2 ± 1.8 to -13.3 ± 1.6 Pg C yr-1 °C-1 in global stratified oceans during 1948-2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming.

  13. OceanNOMADS: Real-time and retrospective access to operational U.S. ocean prediction products

    NASA Astrophysics Data System (ADS)

    Harding, J. M.; Cross, S. L.; Bub, F.; Ji, M.

    2011-12-01

    The National Oceanic and Atmospheric Administration (NOAA) National Operational Model Archive and Distribution System (NOMADS) provides both real-time and archived atmospheric model output from servers at the National Centers for Environmental Prediction (NCEP) and National Climatic Data Center (NCDC) respectively (http://nomads.ncep.noaa.gov/txt_descriptions/marRutledge-1.pdf). The NOAA National Ocean Data Center (NODC) with NCEP is developing a complementary capability called OceanNOMADS for operational ocean prediction models. An NCEP ftp server currently provides real-time ocean forecast output (http://www.opc.ncep.noaa.gov/newNCOM/NCOM_currents.shtml) with retrospective access through NODC. A joint effort between the Northern Gulf Institute (NGI; a NOAA Cooperative Institute) and the NOAA National Coastal Data Development Center (NCDDC; a division of NODC) created the developmental version of the retrospective OceanNOMADS capability (http://www.northerngulfinstitute.org/edac/ocean_nomads.php) under the NGI Ecosystem Data Assembly Center (EDAC) project (http://www.northerngulfinstitute.org/edac/). Complementary funding support for the developmental OceanNOMADS from U.S. Integrated Ocean Observing System (IOOS) through the Southeastern University Research Association (SURA) Model Testbed (http://testbed.sura.org/) this past year provided NODC the analogue that facilitated the creation of an NCDDC production version of OceanNOMADS (http://www.ncddc.noaa.gov/ocean-nomads/). Access tool development and storage of initial archival data sets occur on the NGI/NCDDC developmental servers with transition to NODC/NCCDC production servers as the model archives mature and operational space and distribution capability grow. Navy operational global ocean forecast subsets for U.S waters comprise the initial ocean prediction fields resident on the NCDDC production server. The NGI/NCDDC developmental server currently includes the Naval Research Laboratory Inter-America Seas

  14. Production Characteristics of Oceanic Natural Gas Hydrate Reservoirs

    NASA Astrophysics Data System (ADS)

    Max, M. D.; Johnson, A. H.

    2014-12-01

    -water separation can begin within the seafloor, and specialized production techniques. NGH is the only oceanic hydrocarbon deposit in which pressure can be controlled within the reservoir by balancing conversion and extraction. Oceanic NGH has a very low environmental risk, which also serves to distinguish it from other deepwater hydrocarbon deposits.

  15. Declining global per capita agricultural production and warming oceans threaten food security

    USGS Publications Warehouse

    Funk, Christopher C.; Brown, Molly E.

    2009-01-01

    Despite accelerating globalization, most people still eat food that is grown locally. Developing countries with weak purchasing power tend to import as little food as possible from global markets, suffering consumption deficits during times of high prices or production declines. Local agricultural production, therefore, is critical to both food security and economic development among the rural poor. The level of local agricultural production, in turn, will be determined by the amount and quality of arable land, the amount and quality of agricultural inputs (fertilizer, seeds, pesticides, etc.), as well as farm-related technology, practices and policies. This paper discusses several emerging threats to global and regional food security, including declining yield gains that are failing to keep up with population increases, and warming in the tropical Indian Ocean and its impact on rainfall. If yields continue to grow more slowly than per capita harvested area, parts of Africa, Asia and Central and Southern America will experience substantial declines in per capita cereal production. Global per capita cereal production will potentially decline by 14% between 2008 and 2030. Climate change is likely to further affect food production, particularly in regions that have very low yields due to lack of technology. Drought, caused by anthropogenic warming in the Indian and Pacific Oceans, may also reduce 21st century food availability in some countries by disrupting moisture transports and bringing down dry air over crop growing areas. The impacts of these circulation changes over Asia remain uncertain. For Africa, however, Indian Ocean warming appears to have already reduced rainfall during the main growing season along the eastern edge of tropical Africa, from southern Somalia to northern parts of the Republic of South Africa. Through a combination of quantitative modeling of food balances and an examination of climate change, this study presents an analysis of emerging

  16. African dust carries microbes across the ocean: are they affecting human and ecosystem health?

    USGS Publications Warehouse

    Kellogg, Christina A.; Griffin, Dale W.

    2003-01-01

    Atmospheric transport of dust from northwest Africa to the western Atlantic Ocean region may be responsible for a number of environmental hazards, including the demise of Caribbean corals; red tides; amphibian diseases; increased occurrence of asthma in humans; and oxygen depletion (eutrophication) in estuaries. Studies of satellite images suggest that hundreds of millions of tons of dust are trans-ported annually at relatively low altitudes across the Atlantic Ocean to the Caribbean Sea and southeastern United States. The dust emanates from the expanding Sahara/Sahel desert region in Africa and carries a wide variety of bacteria and fungi. The U.S. Geological Survey, in collaboration with the NASA/Goddard Spaceflight Center, is conducting a study to identify microbes--bacteria, fungi, viruses--transported across the Atlantic in African soil dust. Each year, millions of tons of desert dust blow off the west African coast and ride the trade winds across the ocean, affecting the entire Caribbean basin, as well as the southeastern United States. Of the dust reaching the U.S., Florida receives about 50 percent, while the rest may range as far north as Maine or as far west as Colorado. The dust storms can be tracked by satellite and take about one week to cross the Atlantic.

  17. Deposition of 7Be to Bermuda and the regional ocean: Environmental factors affecting estimates of atmospheric flux to the ocean

    NASA Astrophysics Data System (ADS)

    Kadko, David; Prospero, Joseph

    2011-02-01

    The distribution of 7Be in ocean surface waters is used as tracer of upper ocean transport and atmospheric deposition processes. However, there is very little ocean deposition data available to characterize the temporal and spatial input of 7Be to the oceans and test model results. Here we measure the deposition of 7Be in bulk collectors at two sites at Bermuda over a span of nearly 2 years (April 2007 to January 2009) and compare these rates to the flux required to sustain the inventory of 7Be measured in the nearby Sargasso Sea. The Tudor Hill collector site undersampled (by ˜40%) both the rainfall compared to other Bermuda sites and the 7Be flux required for the ocean inventory. On the other hand, the 7Be flux captured at the Bermuda Institute of Ocean Sciences station site (0.048 dpm cm-2 d-1) matched that expected from the ocean observations. Previously measured long-term atmospheric concentration of 7Be in surface air at Bermuda was used to estimate deposition velocities and scavenging ratios, and our estimates in this marine environment were found to be similar to those measured in continental regions. The deposition of 7Be to the oceans is overwhelmingly determined by wet processes; dry deposition to the ocean surface accounts for only a few percent, at most, of the total deposition to the ocean. We place these measurements in a longer-term and large-scale spatial context by using climatological rainfall data on Bermuda and ocean rainfall estimates from the Global Precipitation Climatology Program and Tropical Rainfall Measuring Mission.

  18. Regional Ocean Products Portal: Transforming Information to Knowledge

    NASA Astrophysics Data System (ADS)

    Howard, M. K.; Kobara, S.; Gayanilo, F. C.; Baum, S. K.; Simoniello, C.; Jochens, A. E.

    2010-12-01

    .S. Integrated Ocean Observing System (IOOS). With IOOS guidance, and cooperation of regional data providers, GCOOS-RA has established a regional interoperable system of systems which has the potential to deliver marine, and coastal marine oceanographic, atmospheric, biogeochemical, and ecosystem related data in an automated and largely unattended way from sensors to products. GCOOS-RA devotes 10% of it’s funding to Education and Outreach activities and we have a number of modeling partners producing terabytes of output. With the interoperable parts of the data delivery system complete, our current challenge has been producing automated workflows that generate useful interactive graphical representations over the web. We have used a variety of commercial and free software packages. Some are net-enabled and can acquire remote datasets. Several are designed for 3D including ITTVIS IDL, Unidata IDV, and IVS’s Fledermaus. This talk will present a survey of software packages we’ve used, our successes and remaining challenges.

  19. Gas production from oceanic Class 2 hydrate accumulations

    SciTech Connect

    Moridis, G.J.; Reagan, M.T.

    2007-02-01

    Gas hydrates are solid crystalline compounds in which gasmolecules are lodged within the lattices of ice crystals. The vastamounts of hydrocarbon gases that are trapped in hydrate deposits in thepermafrost and in deep ocean sediments may constitute a promising energysource. Class 2 hydrate deposits are characterized by a Hydrate-BearingLayer (HBL) that is underlain by a saturated zone of mobile water. Inthis study we investigated three methods of gas production via verticalwell designs. A long perforated interval (covering the hydrate layer andextending into the underlying water zone) yields the highest gasproduction rates (up to 20 MMSCFD), but is not recommended for long-termproduction because of severe flow blockage caused by secondary hydrateand ice. A short perforated interval entirely within the water zoneallows long-term production, but only at rates of 4.5 7 MMSCFD. A newwell design involving localized heating appears to be the most promising,alleviating possible blockage by secondary hydrate and/or ice near thewellbore) and delivering sustainably large, long-term rates (10-15MMSCFD).The production strategy involves a cyclical process. During eachcycle, gas production continuously increases, while the correspondingwater production continuously decreases. Each cycle is concluded by acavitation event (marked by a precipitous pressure drop at the well),brought about by the inability of thesystem to satisfy the constant massproduction rate QM imposed at the well. This is caused by the increasinggas contribution to the production stream, and/or flow inhibition causedby secondary hydrate and/or ice. In the latter case, short-term thermalstimulation removes the blockage. The results show that gas productionincreases (and the corresponding water-to-gas ratio RWGC decreases) withan increasing(a) QM, (b) hydrate temperature (which defines its stabilityfor a given pressure), and (c) intrinsic permeability. Lower initialhydrate saturations lead initially to higher gas

  20. Ocean export production and foraminiferal stable isotopes in the Antarctic Southern Ocean across the mid-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Hasenfratz, A. P.; Martinez-Garcia, A.; Jaccard, S.; Hodell, D. A.; Vance, D.; Bernasconi, S. M.; Greaves, M.; Haug, G. H.

    2014-12-01

    Changes in buoyancy forcing in the Antarctic Zone (AZ) of the Southern Ocean are believed to play an instrumental role in modulating atmospheric CO2 concentrations during glacial cycles by regulating the transfer of carbon between the ocean interior and the atmosphere. Indeed, a million-year-spanning high-resolution excess Barium record from the AZ of the South Atlantic (ODP 1094), which traces changes in export production, shows decreased export production during cold periods suggesting decreased overturning. Here, we extend this AZ export production record back to 1.6 Myr. In addition, we present new carbon and oxygen isotope records of benthic and planktic foraminifera from the same site, complemented by Mg/Ca measurements in some intervals. The interpretation of these new data in the context of other South Atlantic records contributes to a better understanding of Southern Ocean hydrography and its role in modulating glacial/interglacial cycles over the past 1.6 Myr.

  1. Production of desalinated water using ocean thermal energy

    NASA Astrophysics Data System (ADS)

    Rabas, T.; Panchal, C.

    This paper describes an Ocean Thermal Energy Conversion (OTEC) desalination plant that consists of a multistage flash evaporator (MSF), a closed-cycle OTEC power plant, and an appropriate seawater system depending if the desalination plant is land based or floating. OTEC desalination plants of this type are preferred because the production of desalinated water far exceeds that obtained from other OTEC plant types employing the same size seawater system. The focus of the paper is on the multistage flash evaporator. The similarities and differences between conventional MSF and OTEC multistage flash evaporators (OTEC-MSF) are first described. Then the details of the OTEC-MSF evaporator design are discussed and preliminary correlations are recommended for the three major elements: the flash chamber, the moisture removal device, and the condenser. Recent advances such as enhanced condenser tubes, condensers of the compact type, and corrugated-plate moisture separators are introduced into the design. Comparisons of the water production capability, evaporator shell volume, and material cost are then presented for state-of-the-art and the new design concepts.

  2. Production of desalinated water using ocean thermal energy

    SciTech Connect

    Rabas, T.; Panchal, C.

    1991-01-01

    This paper describes an Ocean Thermal Energy Conversion (OTEC) desalination plant that consists of a multistage flash evaporator (MSF), a closed-cycle OTEC power plant, and an appropriate seawater system depending if the desalination plant is land based or floating. OTEC desalination plants of this type are preferred because the production of desalinated water far exceeds that obtained from other OTEC plant types employing the same size seawater system. The focus of the paper is on the multistage flash evaporator. The similarities and differences between conventional MSF and OTEC multistage flash evaporators (OTEC-MSF) are first described. Then the details of the OTEC-MSF evaporator design are discussed and preliminary correlations are recommended for the three major elements: the flash chamber, the moisture removal device, and the condenser. Recent advances such as enhanced condenser tubes, condensers of the compact type, and corrugated-plate moisture separators are introduced into the design. Comparisons of the water production capability, evaporator shell volume, and material cost are then presented for state-of-the-art and the new design concepts. 20 refs., 11 figs., 5 tabs.

  3. Coastal Upwelling off Chile: Ocean Productivity and Surface Sediments

    NASA Astrophysics Data System (ADS)

    Hebbeln, D.; Lamy, F.

    2002-12-01

    The coastal upwelling system of the Peru-Chile Current belongs to the most productive regions in the world oceans. In spite of this fact only very little is known about the sediment distribution in its southern part off the coast of Chile. To increase the knowledge about this region a multi-parameter study of the surface sediment distribution at over 100 sampling sites along the Chilean continental slope between 23°S and 45°S has been carried out. Detailed analyses of sedimentary data (TOC, carbonate, and biogenic opal contents, delta 15N) reveal a close relation to environmental conditions in the region. Coastal upwelling along the Chilean coast, centered around main upwelling centers such as off Antofagasta (23°S), off Lengua de Vaca (30°S), off Valparaiso (33°S), and off Concepci¢n (35-38°S), sustains the high productivity observed in satellite pigment data and in sediment data. However, the highest pigment concentrations are found south of 40°S where prevailing onshore winds of the Southern Westerlies generally prevent coastal upwelling. There, also highest estimated accumulation rates of organic carbon and biogenic opal at the sea floor are found. Thus, the general pattern of a southward increase of surface water productivity known from satellite data is closely reflected in the organic carbon, biogenic opal and ?15N data, although the observation of highest productivity south of the upwelling area is surprising. Probably, this high productivity in the south can be attributed to the advection of (macro-) nutrients by the Antarctic Circumpolar Current, supplying so-called high nutrient-low chlorophyll (HNLC) waters to the Chilean margin. Impinging on the Chilean margin these waters can take up micronutrients such as iron from the strong riverine input and from benthic exchange processes. The combination of macro- and micro-nutrients in this area most likely results in the high productivity of the area between 40°S and 45°S. From there these fertile

  4. Negligible effects of ocean acidification on Eurytemora affinis (Copepoda) offspring production

    NASA Astrophysics Data System (ADS)

    Almén, Anna-Karin; Vehmaa, Anu; Brutemark, Andreas; Bach, Lennart; Lischka, Silke; Stuhr, Annegret; Furuhagen, Sara; Paul, Allanah; Bermúdez, J. Rafael; Riebesell, Ulf; Engström-Öst, Jonna

    2016-02-01

    Ocean acidification is caused by increasing amounts of carbon dioxide dissolving in the oceans leading to lower seawater pH. We studied the effects of lowered pH on the calanoid copepod Eurytemora affinis during a mesocosm experiment conducted in a coastal area of the Baltic Sea. We measured copepod reproductive success as a function of pH, chlorophyll a concentration, diatom and dinoflagellate biomass, carbon to nitrogen (C : N) ratio of suspended particulate organic matter, as well as copepod fatty acid composition. The laboratory-based experiment was repeated four times during 4 consecutive weeks, with water and copepods sampled from pelagic mesocosms enriched with different CO2 concentrations. In addition, oxygen radical absorbance capacity (ORAC) of animals from the mesocosms was measured weekly to test whether the copepod's defence against oxidative stress was affected by pH. We found no effect of pH on offspring production. Phytoplankton biomass, as indicated by chlorophyll a concentration and dinoflagellate biomass, had a positive effect. The concentration of polyunsaturated fatty acids in the females was reflected in the eggs and had a positive effect on offspring production, whereas monounsaturated fatty acids of the females were reflected in their eggs but had no significant effect. ORAC was not affected by pH. From these experiments we conclude that E. affinis seems robust against direct exposure to ocean acidification on a physiological level, for the variables covered in the study. E. affinis may not have faced acute pH stress in the treatments as the species naturally face large pH fluctuations.

  5. Negligible effects of ocean acidification on Eurytemora affinis (Copepoda) offspring production

    NASA Astrophysics Data System (ADS)

    Almén, A.-K.; Vehmaa, A.; Brutemark, A.; Bach, L.; Lischka, S.; Stuhr, A.; Furuhagen, S.; Paul, A.; Bermúdez, R.; Riebesell, U.; Engström-Öst, J.

    2015-10-01

    Ocean acidification is caused by increasing amounts of carbon dioxide dissolving in the oceans leading to lower seawater pH. We studied the effects of lowered pH on the calanoid copepod Eurytemora affinis during a mesocosm experiment conducted in a coastal area of the Baltic Sea. We measured copepod reproductive success as a function of pH, chlorophyll a concentration, diatom and dinoflagellate biomass, carbon to nitrogen (C : N) ratio of suspended particulate organic matter, as well as copepod fatty acid composition. The laboratory-based experiment was repeated four times during four consecutive weeks, with water and copepods sampled from pelagic mesocosms enriched with different CO2 concentrations. In addition, oxygen radical absorbance capacity (ORAC) of animals from the mesocosms was measured weekly to test whether the copepod's defence against oxidative stress was affected by pH. We found no effect of pH on offspring production. Phytoplankton biomass, as indicated by chlorophyll a concentration, had a strong positive effect. The concentration of polyunsaturated fatty acids in the females were reflected in the eggs and had a positive effect on offspring production, whereas monounsaturated fatty acids of the females were reflected in their eggs but had no significant effect. ORAC was not affected by pH. From these experiments we conclude that E. affinis seems robust against direct exposure to ocean acidification on a physiological level, for the variables covered in the study. E. affinis may not have faced acute pH stress in the treatments as the species naturally face large pH fluctuations.

  6. Metabolic differences in temperamental Brahman cattle can affect productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many factors may adversely affect the growth and productivity of livestock. These include stressors associated with management practices, such as weaning, handling relative to transportation, and vaccination, that can modulate growth through the production of stress-related hormones (i.e., cortisol,...

  7. Hydrogen sulfide production in surface layers of sediments in the Atlantic Ocean (from radioisotope data)

    NASA Astrophysics Data System (ADS)

    Lein, A. Yu.; Ivanov, M. V.

    2015-11-01

    The report presents the results of 35S-radioisotope researches of sulfate reduction rates in Holocene sediments (0-20 cm) of the shelf and the continental slope at the eastern coasts of the Atlantic Ocean from 81° N to 25° S, including sediments in the most environmentally hazardous upwelling zones. Data from experiments on the rates of sulfate reduction were used in calculating the production of hydrogen sulfide. The rates of sulfate reduction are comparable at the polar shelf and the equatorial area of the influence of the Congo River (11.9 and 14.96 mg S/m2 day, respectively). It must be acknowledged that the production of microbial diagenetic hydrogen sulfide is first affected by the content and composition of organic matter in the sediments and secondly by the thermal conditions of the basin.

  8. The Global Ocean Data Analysis Project version 2 (GLODAPv2) - an internally consistent data product for the world ocean

    NASA Astrophysics Data System (ADS)

    Olsen, Are; Key, Robert M.; van Heuven, Steven; Lauvset, Siv K.; Velo, Anton; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; Jutterström, Sara; Steinfeldt, Reiner; Jeansson, Emil; Ishii, Masao; Pérez, Fiz F.; Suzuki, Toru

    2016-08-01

    Version 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. The data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. This compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg-1 in dissolved inorganic carbon, 6 µmol kg-1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracers.The original data and their documentation and doi codes are available at the Carbon Dioxide Information Analysis Center (oceans/GLODAPv2/" target="_blank">http://cdiac.ornl.gov/oceans/GLODAPv2/). This site also provides access to the calibrated data product, which is provided as a single global file or four regional ones - the Arctic, Atlantic, Indian, and Pacific oceans - under the doi:10.3334/CDIAC

  9. Polyhalogenated Very Short Live Substances in the Atlantic Ocean, and their Linkages with Ocean Primary Production

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Yvon-Lewis, S. A.; Hu, L.; Bianchi, T. S.; Campbell, L.; Smith, R. W.

    2011-12-01

    The Halocarbon Air-Sea Transect - Atlantic (HalocAST-A) cruise was conducted aboard FS Polarstern during the ANT-XXVII/1 expedition. The ship departed from Bremerhaven, Germany on October 25th and arrived in Cape Town, South Africa on November 24th in 2010. The HalocAST-A cruise was devoted to studying air-sea fluxes of a suite of halocarbon compounds. Atmospheric mixing ratios and seawater concentrations of the halocarbons were continuously measured with the gas chromatograph - mass spectrometer (GC-MS). This study focuses on the polyhalogenated very short lived substances (VSLSs) such as bromoform (CHBr3), dibromomethane (CH2Br2), chlorodibromomethane (CHClBr2), and bromodichloromethane (CHBrCl2). The goal of this study is to examine the distributions of these compounds and possible relationship between their emissions and oceanic primary production. Therefore, along with the halocarbon concentrations, parameters like dissolved organic carbon concentrations, nutrient concentrations, pigment concentrations, and picoplankton and heterotrophic bacteria counts were also determined. The observed saturation anomalies indicated these VSLSs were supersaturated for almost the entire duration of the cruise. The highest seawater concentrations for these compounds were observed near the Canary Islands. Air mixing ratios were also elevated in this region. The net fluxes for CHBr3, CH2Br2, CHClBr2, and CHBrCl2 were 13.8 nmol m-2 d-1, 4.5 nmol m-2 d-1, 4.5 nmol m-2 d-1 and 1.2 nmol m-2 d-1, respectively. During the HalocAST-A cruise, these compounds exhibit similar trends with total chlorophyll a. Contributions from selected phytoplankton group will be further assessed through the use of individual pigment biomarkers.

  10. A reduction in marine primary productivity driven by rapid warming over the tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Roxy, Mathew Koll; Modi, Aditi; Murtugudde, Raghu; Valsala, Vinu; Panickal, Swapna; Prasanna Kumar, S.; Ravichandran, M.; Vichi, Marcello; Lévy, Marina

    2016-01-01

    Among the tropical oceans, the western Indian Ocean hosts one of the largest concentrations of marine phytoplankton blooms in summer. Interestingly, this is also the region with the largest warming trend in sea surface temperatures in the tropics during the past century—although the contribution of such a large warming to productivity changes has remained ambiguous. Earlier studies had described the western Indian Ocean as a region with the largest increase in phytoplankton during the recent decades. On the contrary, the current study points out an alarming decrease of up to 20% in phytoplankton in this region over the past six decades. We find that these trends in chlorophyll are driven by enhanced ocean stratification due to rapid warming in the Indian Ocean, which suppresses nutrient mixing from subsurface layers. Future climate projections suggest that the Indian Ocean will continue to warm, driving this productive region into an ecological desert.

  11. Snapshot prediction of carbon productivity, carbon and protein content in a Southern Ocean diatom using FTIR spectroscopy

    PubMed Central

    Sackett, Olivia; Petrou, Katherina; Reedy, Brian; Hill, Ross; Doblin, Martina; Beardall, John; Ralph, Peter; Heraud, Philip

    2016-01-01

    Diatoms, an important group of phytoplankton, bloom annually in the Southern Ocean, covering thousands of square kilometers and dominating the region's phytoplankton communities. In their role as the major food source to marine grazers, diatoms supply carbon, nutrients and energy to the Southern Ocean food web. Prevailing environmental conditions influence diatom phenotypic traits (for example, photophysiology, macromolecular composition and morphology), which in turn affect the transfer of energy, carbon and nutrients to grazers and higher trophic levels, as well as oceanic biogeochemical cycles. The paucity of phenotypic data on Southern Ocean phytoplankton limits our understanding of the ecosystem and how it may respond to future environmental change. Here we used a novel approach to create a ‘snapshot' of cell phenotype. Using mass spectrometry, we measured nitrogen (a proxy for protein), total carbon and carbon-13 enrichment (carbon productivity), then used this data to build spectroscopy-based predictive models. The models were used to provide phenotypic data for samples from a third sample set. Importantly, this approach enabled the first ever rate determination of carbon productivity from a single time point, circumventing the need for time-series measurements. This study showed that Chaetoceros simplex was less productive and had lower protein and carbon content during short-term periods of high salinity. Applying this new phenomics approach to natural phytoplankton samples could provide valuable insight into understanding phytoplankton productivity and function in the marine system. PMID:26230047

  12. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production

    PubMed Central

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  13. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role.

  14. Recent Changes in Primary Production in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Arrigo, K. R.

    2015-12-01

    Over the last decade and a half, the continued loss of sea is in the Arctic ocean has led to a dramatic increase in marine net primary production (NPP). Increased annual NPP is often, but not always, associated with reduced sea-ice extent and a longer phytoplankton growing season (fewer days of ice cover). However, spatial patterns of enhanced annual NPP suggest that increased nutrient fluxes may also play a role. For instance, the greatest increases in Arctic NPP have been observed on the interior shelves in waters near the shelfbreak. These are areas where additional nutrients may become increasingly available as the sea ice retreats toward the pole, facilitated by increased shelfbreak upwelling. The eastern Arctic, which receives a large fraction of the high-nutrient Pacific water, exhibits an unusual pattern whereby increased annual NPP in more upstream waters of the Chukchi and Beaufort seas is offset by lower annual NPP in downstream regions of the Greenland Sea. The reason for the decline in NPP in downstream waters is unclear, especially if upstream nutrient supplies and NPP are increasing. Perhaps higher NPP on the Chukchi shelf has caused an increase in the rate of sediment denitrification, resulting in larger losses of fixed nitrogen. This would require that the large increase in annual NPP in the Beaufort Sea be driven by some other nutrient source, perhaps local shelfbreak upwelling. More efficient utilization of these nutrients, due perhaps to longer growing seasons, could eventually reduce inventories downstream, resulting in no change in annual NPP in the Baffin sector and a decline over the outflow shelves near Greenland. This is consistent with the observation that large increases in Chukchi Sea NPP preceded significant declines in Greenland Sea waters by more than a year. More work needs to be done to understand the factors responsible for both the large-scale and the small-scale patterns in annual NPP.

  15. Molecular biology in studies of oceanic primary production

    SciTech Connect

    LaRoche, J.; Falkowski, P.G.; Geider, R.

    1992-07-01

    Remote sensing and the use of moored in situ instrumentation has greatly improved our ability to measure phytoplankton chlorophyll and photosynthesis on global scales with high temporal resolution. However, the interpretation of these measurements and their significance with respect to the biogeochemical cycling of carbon relies on their relationship with physiological and biochemical processes in phytoplankton. For example, the use of satellite images of surface chlorophyll to estimate primary production is often based on the functional relationship between photosynthesis and irradiance. A variety of environmental factors such as light, temperature, nutrient availability affect the photosynthesis/irradiance (P vs I) relationship in phytoplankton. We present three examples showing how molecular biology can be used to provide basic insight into the factors controlling primary productivity at three different levels of complexity: 1. Studies of light intensity regulation in unicellular alga show how molecular biology can help understand the processing of environmental cues leading to the regulation of photosynthetic gene expression. 2. Probing of the photosynthetic apparatus using molecular techniques can be used to test existing mechanistic models derived from the interpretation of physiological and biophysical measurements. 3. Exploratory work on the expression of specific proteins during nutrient-limited growth of phytoplankton may lead to the identification and production of molecular probes for field studies.

  16. Molecular biology in studies of oceanic primary production

    SciTech Connect

    LaRoche, J.; Falkowski, P.G. ); Geider, R. . Coll. of Marine Studies)

    1992-01-01

    Remote sensing and the use of moored in situ instrumentation has greatly improved our ability to measure phytoplankton chlorophyll and photosynthesis on global scales with high temporal resolution. However, the interpretation of these measurements and their significance with respect to the biogeochemical cycling of carbon relies on their relationship with physiological and biochemical processes in phytoplankton. For example, the use of satellite images of surface chlorophyll to estimate primary production is often based on the functional relationship between photosynthesis and irradiance. A variety of environmental factors such as light, temperature, nutrient availability affect the photosynthesis/irradiance (P vs I) relationship in phytoplankton. We present three examples showing how molecular biology can be used to provide basic insight into the factors controlling primary productivity at three different levels of complexity: 1. Studies of light intensity regulation in unicellular alga show how molecular biology can help understand the processing of environmental cues leading to the regulation of photosynthetic gene expression. 2. Probing of the photosynthetic apparatus using molecular techniques can be used to test existing mechanistic models derived from the interpretation of physiological and biophysical measurements. 3. Exploratory work on the expression of specific proteins during nutrient-limited growth of phytoplankton may lead to the identification and production of molecular probes for field studies.

  17. Ocean Acidification Affects Redox-Balance and Ion-Homeostasis in the Life-Cycle Stages of Emiliania huxleyi

    PubMed Central

    Rokitta, Sebastian D.; John, Uwe; Rost, Björn

    2012-01-01

    Ocean Acidification (OA) has been shown to affect photosynthesis and calcification in the coccolithophore Emiliania huxleyi, a cosmopolitan calcifier that significantly contributes to the regulation of the biological carbon pumps. Its non-calcifying, haploid life-cycle stage was found to be relatively unaffected by OA with respect to biomass production. Deeper insights into physiological key processes and their dependence on environmental factors are lacking, but are required to understand and possibly estimate the dynamics of carbon cycling in present and future oceans. Therefore, calcifying diploid and non-calcifying haploid cells were acclimated to present and future CO2 partial pressures (pCO2; 38.5 Pa vs. 101.3 Pa CO2) under low and high light (50 vs. 300 µmol photons m−2 s−1). Comparative microarray-based transcriptome profiling was used to screen for the underlying cellular processes and allowed to follow up interpretations derived from physiological data. In the diplont, the observed increases in biomass production under OA are likely caused by stimulated production of glycoconjugates and lipids. The observed lowered calcification under OA can be attributed to impaired signal-transduction and ion-transport. The haplont utilizes distinct genes and metabolic pathways, reflecting the stage-specific usage of certain portions of the genome. With respect to functionality and energy-dependence, however, the transcriptomic OA-responses resemble those of the diplont. In both life-cycle stages, OA affects the cellular redox-state as a master regulator and thereby causes a metabolic shift from oxidative towards reductive pathways, which involves a reconstellation of carbon flux networks within and across compartments. Whereas signal transduction and ion-homeostasis appear equally OA-sensitive under both light intensities, the effects on carbon metabolism and light physiology are clearly modulated by light availability. These interactive effects can be attributed

  18. Product design enhancement using apparent usability and affective quality.

    PubMed

    Seva, Rosemary R; Gosiaco, Katherine Grace T; Santos, Ma Crea Eurice D; Pangilinan, Denise Mae L

    2011-03-01

    In this study, apparent usability and affective quality were integrated in a design framework called the Usability Perception and Emotion Enhancement Model (UPEEM). The UPEEM was validated using structural equation modeling (SEM). The methodology consists of four phases namely product selection, attribute identification, design alternative generation, and design alternative evaluation. The first stage involved the selection of a product that highly involves the consumer. In the attribute identification stage, design elements of the product were identified. The possible values of these elements were also determined for use in the experimentation process. Design of experiments was used to identify how the attributes will be varied in the design alternative stage and which of the attributes significantly contribute to affective quality, apparent usability, and desirability in the design evaluation stage. Results suggest that product attributes related to form are relevant in eliciting intense affect and perception of usability in mobile phones especially those directly related to functionality and aesthetics. This study considered only four product attributes among so many due to the constraints of the research design employed. Attributes related to aesthetic perception of a product enhance apparent usability such as those related to dimensional ratios.

  19. Forcings of nutrient, oxygen, and primary production interannual variability in the southeast Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bachèlery, M.-L.; Illig, S.; Dadou, I.

    2016-08-01

    The recurrent occurrences of interannual warm and cold events along the coast of Africa have been intensively studied because of their striking effects on climate and fisheries. Using sensitivity experimentation based on a coupled physical/biogeochemical model, we show that the oceanic remote equatorial forcing explains more than 85% of coastal interannual nitrate and oxygen fluctuations along the Angolan and Namibian coasts up to the Benguela Upwelling System (BUS). These events, associated with poleward propagations of upwelling and downwelling Coastal Trapped Waves (CTW), are maximum in subsurface and controlled by physical advection processes. Surprisingly, an abrupt change in the CTW biogeochemical signature is observed in the BUS, associated with mixed vertical gradients due to the strong local upwelling dynamics. Coastal modifications of biogeochemical features result in significant primary production variations that may affect fisheries habitats and coastal biodiversity along the southwestern African coasts and in the BUS.

  20. Impact of sea-ice biology on overall primary production in a biophysical model of the pan-Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Dupont, Frédéric

    2012-08-01

    The contribution of sea-ice biology and impact of Arctic warming on overall primary production in a Pan-Arctic ocean model are investigated in a 57 year (1950-2006) simulation at coarse resolution using a simple ecosystem model. The ice biology model formally represents the growth and aggregation of micro algae into an ice-water interface, nearly undisturbed by surface mixed layer dynamics. The importance of this so-called ‘ice-algae’ stems from their significant contribution to the total primary production (up to 50% depending on the locations, according to observations described in Gosselin et al. (1997). Simple 1D tests reveal that, depending on their initial biomass and light availability, ice algae can affect the temporal variation of surface nutrients, while they marginally impact the total primary production, or the long term position of the nutricline. The sea-ice primary production is found in the model to be as high as 40% of the total primary production depending on the location and 7.5% for the whole Arctic. The modeled primary production of the ocean is negatively correlated to the September ice cover whereas the production in the ice is more weakly positively correlated. Because of the negative correlation between sea ice cover and pelagic primary production, the short term response to the continuing ice decline will be an increased total production as seen in the model, while the ice algae production would decline.

  1. The Global Ocean Data Analysis Project version 2 (GLODAPv2) – an internally consistent data product for the world ocean

    DOE PAGES

    Olsen, Are; Key, Robert M.; van Heuven, Steven; ...

    2016-08-15

    Version 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. Themore » data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. In conclusion, this compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg-1 in dissolved inorganic carbon, 6 µmol kg-1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracers.« less

  2. The Global Ocean Data Analysis Project version 2 (GLODAPv2) – an internally consistent data product for the world ocean

    SciTech Connect

    Olsen, Are; Key, Robert M.; van Heuven, Steven; Lauvset, Siv K.; Velo, Anton; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; Jutterström, Sara; Steinfeldt, Reiner; Jeansson, Emil; Ishii, Masao; Pérez, Fiz F.; Suzuki, Toru

    2016-08-15

    Version 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. The data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. In conclusion, this compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg-1 in dissolved inorganic carbon, 6 µmol kg-1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracers.

  3. Modeling the role of nitrification in open ocean productivity and the nitrogen cycle.

    PubMed

    Yool, Andrew

    2011-01-01

    The ocean is an important component of the global carbon cycle, and currently serves as the principal sink for anthropogenic CO(2) from the atmosphere. A key role in the natural oceanic carbon cycle is played by the plankton ecosystem, which acts to elevate the storage capacity of the ocean, but it is believed that this will experience change in the future in response to anthropogenic forcing. One of the approaches used to understand and forecast the oceanic carbon cycle is ecosystem modeling, and this is typically grounded on the nitrogen cycle because of the strong regulatory role this element plays in biological productivity. Nitrification is one of the central processes in the oceanic nitrogen cycle, one whose role may change in the future, but also one with a particular relevance to observational efforts to quantify the biological carbon cycle. Here, we describe and summarize current efforts to model nitrification in pelagic open ocean ecosystems, and look forward to future avenues for progress.

  4. Indonesian throughflow nutrient fluxes and their potential impact on Indian Ocean productivity

    NASA Astrophysics Data System (ADS)

    Ayers, Jennifer M.; Strutton, Peter G.; Coles, Victoria J.; Hood, Raleigh R.; Matear, Richard J.

    2014-07-01

    The Indonesian throughflow (ITF) is a chokepoint in the upper ocean thermohaline circulation, carrying Pacific waters through the strongly mixed Indonesian Seas and into the Indian Ocean. Yet the influence of the ITF on biogeochemical fluxes into the Indian Ocean is largely unknown. This study determines the first depth- and time-resolved nitrate, phosphate, and silicate fluxes at the three main exit passages of the ITF: Lombok Strait, Ombai Strait, and Timor Passage. Nutrient flux as well as its variability with depth and time differs greatly between the passages. We estimate the effective flux of nutrients into the Indian Ocean by accounting for existing nutrients in the basin and find it largest in the upper 300-400 m. This suggests that the majority of ITF nutrient supply to the Indian Ocean is to thermocline waters, where it is likely to support new production and significantly impact Indian Ocean biogeochemical cycling.

  5. DISCOVER Near Real-Time Ocean Data Products: Examples of Uses and Limitations

    NASA Astrophysics Data System (ADS)

    Smith, D. K.; Wentz, F. J.; Gentemann, C. L.

    2010-12-01

    Scientists at Remote Sensing Systems produce satellite microwave ocean data products for DISCOVER, a NASA MEaSUREs project. These ocean products include ocean surface winds, sea surface temperatures, atmospheric water vapor, cloud liquid water and rain rates created from passive microwave instrument data including that from SSM/I, TMI, AMSR-E, SSMIS and WindSat. Many users download DISCOVER data products in near real-time and use them within their specific applications. For example, some of the applications include ocean weather assessment for military sortie determination, sea surface temperature front identification for use by fishermen, and whale and turtle habitat monitoring. We will present the processing steps used to create the near real-time DISCOVER data, show several examples of user applications and discuss the benefits and limitations users find in applying our data products to their needs.

  6. Inter-Sensor Comparison of Satellite Ocean Color Products from GOCI and MODIS

    DTIC Science & Technology

    2013-02-26

    Ocean Model (NCOM). 15. SUBJECT TERMS satellite ocean color products, GOCI, MODIS, phytoplankton 16. SECURITY CLASSIFICATION OF: a. REPORT...region. The GOCI FLH products were generated using nLw at bands 5, 6 and 7. 3. Results and Discussion: Phytoplankton blooms develop over the course of a...few days to a week and the complete dynamics of the blooms are not captured by individual LEO sensors. The physiology of phytoplankton cells

  7. Solar Irradiance Changes and Phytoplankton Productivity in Earth's Ocean Following Astrophysical Ionizing Radiation Events

    NASA Astrophysics Data System (ADS)

    Neale, Patrick J.; Thomas, Brian C.

    2016-04-01

    Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer (>600 nm) wavelengths of photosynthetically available radiation (PAR, 400-700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short-wavelength PAR. Here, we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response, which was developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and on remote-sensing-based observations of spectral water transparency, temperature, wind speed, and mixed layer depth. Predicted productivity declined after a simulated ionizing event, but the effect integrated over the water column was small. For integrations taking into account the full depth range of PAR transmission (down to 0.1% of utilizable PAR), the decrease was at most 2-3% (depending on strain), with larger effects (5-7%) for integrations just to the depth of the surface mixed layer. The deeper integrations were most affected by the decreased utilizable PAR at depth due to the NO2 haze, whereas shallower integrations were most affected by the increased surface UV. Several factors tended to dampen the magnitude of productivity responses relative to increases in surface-damaging radiation, for example, most inhibition in the modeled strains is caused by UVA and PAR, and the greatest relative increase in damaging exposure is predicted to occur in the winter when UV and productivity are low.

  8. Solar Irradiance Changes and Phytoplankton Productivity in Earth's Ocean Following Astrophysical Ionizing Radiation Events.

    PubMed

    Neale, Patrick J; Thomas, Brian C

    2016-04-01

    Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer (>600 nm) wavelengths of photosynthetically available radiation (PAR, 400-700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short-wavelength PAR. Here, we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response, which was developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and on remote-sensing-based observations of spectral water transparency, temperature, wind speed, and mixed layer depth. Predicted productivity declined after a simulated ionizing event, but the effect integrated over the water column was small. For integrations taking into account the full depth range of PAR transmission (down to 0.1% of utilizable PAR), the decrease was at most 2-3% (depending on strain), with larger effects (5-7%) for integrations just to the depth of the surface mixed layer. The deeper integrations were most affected by the decreased utilizable PAR at depth due to the NO2 haze, whereas shallower integrations were most affected by the increased surface UV. Several factors tended to dampen the magnitude of productivity responses relative to increases in surface-damaging radiation, for example, most inhibition in the modeled strains is caused by UVA and PAR, and the greatest relative increase in damaging exposure is predicted to occur in the winter when UV and productivity are low.

  9. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming

    PubMed Central

    Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-01-01

    Abstract Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from −15.2 ± 1.8 to −13.3 ± 1.6 Pg C yr−1 °C−1 in global stratified oceans during 1948–2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming. PMID:27867233

  10. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming.

    PubMed

    Wang, Rong; Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-12-28

    Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from -15.2 ± 1.8 to -13.3 ± 1.6 Pg C yr(-1) °C(-1) in global stratified oceans during 1948-2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming.

  11. MET2 affects production of hydrogen sulfide during wine fermentation.

    PubMed

    Huang, Chien; Roncoroni, Miguel; Gardner, Richard C

    2014-08-01

    The production of hydrogen sulfide (H2S) during yeast fermentation contributes negatively to wine aroma. We have mapped naturally occurring mutations in commercial wine strains that affect production of H2S. A dominant R310G mutant allele of MET2, which encodes homoserine O-acetyltransferase, is present in several wine yeast strains as well as in the main lab strain S288c. Reciprocal hemizygosity and allele swap experiments demonstrated that the MET2 R310G allele confers reduced H2S production. Mutations were also identified in genes encoding the two subunits of sulfite reductase, MET5 and MET10, which were associated with reduced H2S production. The most severe of these, an allele of MET10, showed five additional phenotypes: reduced growth rate on sulfate, elevated secretion of sulfite, and reduced production in wine of three volatile sulfur compounds: methionol, carbon disulfide and methylthioacetate. Alleles of MET5 and MET10, but not MET2, affected H2S production measured by colour assays on BiGGY indicator agar, but MET2 effects were seen when bismuth was added to agar plates made with Sauvignon blanc grape juice. Collectively, the data are consistent with the hypothesis that H2S production during wine fermentation results predominantly from enzyme activity in the sulfur assimilation pathway. Lower H2S production results from mutations that reduce the activity of sulfite reductase, the enzyme that produces H2S, or that increase the activity of L-homoserine-O-acetyltransferase, which produces substrate for the next step in the sulfur assimilation pathway.

  12. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

    PubMed Central

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

  13. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    PubMed

    Ow, Yan X; Uthicke, Sven; Collier, Catherine J

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

  14. Corrections to the MODIS Aqua Calibration Derived From MODIS Aqua Ocean Color Products

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard; Franz, Bryan Alden

    2013-01-01

    Ocean color products such as, e.g., chlorophyll-a concentration, can be derived from the top-of-atmosphere radiances measured by imaging sensors on earth-orbiting satellites. There are currently three National Aeronautics and Space Administration sensors in orbit capable of providing ocean color products. One of these sensors is the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, whose ocean color products are currently the most widely used of the three. A recent improvement to the MODIS calibration methodology has used land targets to improve the calibration accuracy. This study evaluates the new calibration methodology and describes further calibration improvements that are built upon the new methodology by including ocean measurements in the form of global temporally averaged water-leaving reflectance measurements. The calibration improvements presented here mainly modify the calibration at the scan edges, taking advantage of the good performance of the land target trending in the center of the scan.

  15. Glacial cycles drive variations in the production of oceanic crust.

    PubMed

    Crowley, John W; Katz, Richard F; Huybers, Peter; Langmuir, Charles H; Park, Sung-Hyun

    2015-03-13

    Glacial cycles redistribute water between oceans and continents, causing pressure changes in the upper mantle, with consequences for the melting of Earth's interior. Using Plio-Pleistocene sea-level variations as a forcing function, theoretical models of mid-ocean ridge dynamics that include melt transport predict temporal variations in crustal thickness of hundreds of meters. New bathymetry from the Australian-Antarctic ridge shows statistically significant spectral energy near the Milankovitch periods of 23, 41, and 100 thousand years, which is consistent with model predictions. These results suggest that abyssal hills, one of the most common bathymetric features on Earth, record the magmatic response to changes in sea level. The models and data support a link between glacial cycles at the surface and mantle melting at depth, recorded in the bathymetric fabric of the sea floor.

  16. Enhanced Carbohydrate Production by Phytoplankton of the Southern Ocean in Response to Iron Fertilization

    NASA Astrophysics Data System (ADS)

    van Oijen, T.; Veldhuis, M. J.; van Leeuwe, M. A.; de Baar, H. J.

    2002-12-01

    Iron concentrations in the Southern Ocean are generally low. At these concentrations microalgal growth, in particular of large diatoms, is affected because iron plays a central role in photosynthesis and several metabolic processes. During the Polarstern 2000 iron release experiment, we studied the effect of in situ iron enrichment on the microalgal production and consumption of water-extractable carbohydrates. The experiment was performed in the Southern Polar Frontal Zone and lasted three weeks. During the course of the experiment, discrete samples were taken along vertical profiles (0-100m), both in the center of the iron enriched patch and outside the patch. In the patch, the carbohydrate concentration in the particulate fraction had doubled at the end of the experiment. An increasing part of the carbohydrates was produced by large diatom cells. Outside the patch, little changes were observed. On day 6, 10 and 19 after the release, seawater from inside and outside the patch was incubated on deck for 24h. In all three deck incubations, the diurnal production and nocturnal consumption of carbohydrates by phytoplankton were higher in iron-enriched bottles. Concluding, carbohydrate production showed to be a sensitive parameter that clearly indicated enhanced phytoplankton growth in response to iron fertilization. This study contributes to a better understanding of factors governing phytoplankton growth in High Nitrogen Low Chlorophyll areas.

  17. The Influence of Sea Ice on Primary Production in the Southern Ocean: A Satellite Perspective

    NASA Technical Reports Server (NTRS)

    Smith, Walker O., Jr.; Comiso, Josefino C.

    2007-01-01

    Sea ice in the Southern Ocean is a major controlling factor on phytoplankton productivity and growth, but the relationship is modified by regional differences in atmospheric and oceanographic conditions. We used the phytoplankton biomass (binned at 7-day intervals), PAR and cloud cover data from SeaWiFS, ice concentrations data from SSM/I and AMSR-E, and sea-surface temperature data from AVHRR, in combination with a vertically integrated model to estimate primary productivity throughout the Southern Ocean (south of 60"s). We also selected six areas within the Southern Ocean and analyzed the variability of the primary productivity and trends through time, as well as the relationship of sea ice to productivity. We found substantial interannual variability in productivity from 1997 - 2005 in all regions of the Southern Ocean, and this variability appeared to be driven in large part by ice dynamics. The most productive regions of Antarctic waters were the continental shelves, which showed the earliest growth, the maximum biomass, and the greatest areal specific productivity. In contrast, no large, sustained blooms occurred in waters of greater depth (> 1,000 m). We suggest that this is due to the slightly greater mixed layer depths found in waters off the continental shelf, and that the interactive effects of iron and irradiance (that is, increased iron requirements in low irradiance environments) result in the limitation of phytoplankton biomass over large regions of the Southern Ocean.

  18. Ocean acidification causes bleaching and productivity loss in coral reef builders.

    PubMed

    Anthony, K R N; Kline, D I; Diaz-Pulido, G; Dove, S; Hoegh-Guldberg, O

    2008-11-11

    Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of framework builders. In addition, acidification is likely to affect the relationship between corals and their symbiotic dinoflagellates and the productivity of this association. However, little is known about how acidification impacts on the physiology of reef builders and how acidification interacts with warming. Here, we report on an 8-week study that compared bleaching, productivity, and calcification responses of crustose coralline algae (CCA) and branching (Acropora) and massive (Porites) coral species in response to acidification and warming. Using a 30-tank experimental system, we manipulated CO(2) levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO(2) is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds. We propose that CO(2) induces bleaching via its impact on photoprotective mechanisms of the photosystems. Overall, acidification impacted more strongly on bleaching and productivity than on calcification. Interestingly, the intermediate, warm CO(2) scenario led to a 30% increase in productivity in Acropora, whereas high CO(2) lead to zero productivity in both corals. CCA were most sensitive to acidification, with high CO(2) leading to negative productivity and high rates of net dissolution. Our findings suggest that sensitive reef-building species such as CCA may be pushed beyond their thresholds for growth and survival within the next few decades whereas corals will show delayed and mixed responses.

  19. Oceanic isoprene and DMS distributions during low-productive conditions in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Booge, Dennis; Zavarsky, Alexander; Bell, Thomas; Marandino, Christa

    2015-04-01

    Despite their low abundances compared to the long lived greenhouse gases such as carbon dioxide and methane, short-lived trace gases produced in the oceans have been recognized as playing an important role in atmospheric chemistry and climate. Both isoprene and dimethylsulfide (DMS) are biogenic trace gases produced in the ocean and due to their supersaturation in the surface ocean are emitted to the atmosphere. Once emitted, they produce secondary organic aerosols via fast oxidation processes in the atmosphere (isoprene has a lifetime on approximately 1 hour and DMS 1 day). Consequently, both are hypothesized to significantly impact the radiative balance of the marine atmosphere. However, the strength of this impact is controversial. It is known that the emissions of these compounds to the atmosphere are critically controlled by surface ocean biogeochemical and physical factors which are, especially for isoprene, poorly quantified and unpredictable. Therefore, in order to more fully understand the role of isoprene and DMS on the marine atmosphere, more studies of their distributions, controlling factors, and air-sea exchange are urgently needed. Here we present preliminary measurements of isoprene and DMS concentrations from the SPACES and OASIS campaigns onboard the R/V Sonne that took place from July 8th to August 7th starting in Durban, South Africa and ending in Malé, Maledives. An improved purge and trap technique coupled with a gas chromatograph-mass spectrometer (GC-MS) was used to measure isoprene and DMS in one run for both surface and depth profile samples. In addition, an atmospheric pressure chemical ionization mass spectrometer (AP-CIMS) was used to perform continuous surface measurements of these compounds. The discrete surface measurements were made every three hours using a submersible pump located in the ship's moonpool at 6 m depth. For depth profile measurements samples were taken from 5 m to about 100 m depth. There have been no reported

  20. Community structure across a large-scale ocean productivity gradient: Marine bird assemblages of the Southern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Hyrenbach, K. David; Veit, Richard R.; Weimerskirch, Henri; Metzl, Nicolas; Hunt, George L., Jr.

    2007-07-01

    Our objective was to understand how marine birds respond to oceanographic variability across the Southern Indian Ocean using data collected during an 16-day cruise (4-21 January 2003). We quantified concurrent water mass distributions, ocean productivity patterns, and seabird distributions across a heterogeneous pelagic ecosystem from subtropical to sub-Antarctic waters. We surveyed 5155 km and sighted 15,606 birds from 51 species, and used these data to investigate how seabirds respond to spatial variability in the structure and productivity of the ocean. We addressed two spatial scales: the structure of seabird communities across macro-mega scale (1000 s km) biogeographic domains, and their coarse-scale (10 s km) aggregation at hydrographic and bathymetric gradients. Both seabird density and species composition changed with latitudinal and onshore-offshore gradients in depth, water temperature, and chlorophyll-a concentration. The average seabird density increased across the subtropical convergence (STC) from 2.4 birds km -2 in subtropical waters to 23.8 birds km -2 in sub-Antarctic waters. The composition of the avifauna also differed across biogeographic domains. Prions ( Pachyptila spp.) accounted for 57% of all sub-Antarctic birds, wedge-tailed shearwaters ( Puffinus pacificus) accounted for 46% of all subtropical birds, and Indian Ocean yellow-nosed albatross ( Thallasarche carteri) accounted for 32% of all birds in the STC. While surface feeders were the most abundant foraging guild across the study area, divers were disproportionately more numerous in the sub-Antarctic domain, and plungers were disproportionately more abundant in subtropical waters. Seabird densities were also higher within shallow shelf-slope regions, especially in sub-Antarctic waters, where large numbers of breeding seabirds concentrated. However, we did not find elevated seabird densities along the STC, suggesting that this broad frontal region is not a site of enhanced aggregation.

  1. Parameters Affecting Ethyl Ester Production by Saccharomyces cerevisiae during Fermentation▿

    PubMed Central

    Saerens, S. M. G.; Delvaux, F.; Verstrepen, K. J.; Van Dijck, P.; Thevelein, J. M.; Delvaux, F. R.

    2008-01-01

    Volatile esters are responsible for the fruity character of fermented beverages and thus constitute a vital group of aromatic compounds in beer and wine. Many fermentation parameters are known to affect volatile ester production. In order to obtain insight into the production of ethyl esters during fermentation, we investigated the influence of several fermentation variables. A higher level of unsaturated fatty acids in the fermentation medium resulted in a general decrease in ethyl ester production. On the other hand, a higher fermentation temperature resulted in greater ethyl octanoate and decanoate production, while a higher carbon or nitrogen content of the fermentation medium resulted in only moderate changes in ethyl ester production. Analysis of the expression of the ethyl ester biosynthesis genes EEB1 and EHT1 after addition of medium-chain fatty acid precursors suggested that the expression level is not the limiting factor for ethyl ester production, as opposed to acetate ester production. Together with the previous demonstration that provision of medium-chain fatty acids, which are the substrates for ethyl ester formation, to the fermentation medium causes a strong increase in the formation of the corresponding ethyl esters, this result further supports the hypothesis that precursor availability has an important role in ethyl ester production. We concluded that, at least in our fermentation conditions and with our yeast strain, the fatty acid precursor level rather than the activity of the biosynthetic enzymes is the major limiting factor for ethyl ester production. The expression level and activity of the fatty acid biosynthetic enzymes therefore appear to be prime targets for flavor modification by alteration of process parameters or through strain selection. PMID:17993562

  2. Factors affecting methane production and mitigation in ruminants.

    PubMed

    Shibata, Masaki; Terada, Fuminori

    2010-02-01

    Methane (CH(4)) is the second most important greenhouse gas (GHG) and that emitted from enteric fermentation in livestock is the single largest source of emissions in Japan. Many factors influence ruminant CH(4) production, including level of intake, type and quality of feeds and environmental temperature. The objectives of this review are to identify the factors affecting CH(4) production in ruminants, to examine technologies for the mitigation of CH(4) emissions from ruminants, and to identify areas requiring further research. The following equation for CH(4) prediction was formulated using only dry matter intake (DMI) and has been adopted in Japan to estimate emissions from ruminant livestock for the National GHG Inventory Report: Y = -17.766 + 42.793X - 0.849X(2), where Y is CH(4) production (L/day) and X is DMI (kg/day). Technologies for the mitigation of CH(4) emissions from ruminants include increasing productivity by improving nutritional management, the manipulation of ruminal fermentation by changing feed composition, the addition of CH(4) inhibitors, and defaunation. Considering the importance of ruminant livestock, it is essential to establish economically feasible ways of reducing ruminant CH(4) production while improving productivity; it is therefore critical to conduct a full system analysis to select the best combination of approaches or new technologies to be applied under long-term field conditions.

  3. Analysis of Atmosphere-Ocean Surface Flux Feedbacks in Recent Satellite and Model Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Roberts, J. Brent; Robertson, F. R.; Clayson, C. A.

    2010-01-01

    Recent investigations have examined observations in an attempt to determine when and how the ocean forces the atmosphere, and vice versa. These studies focus primarily on relationships between sea surface temperature anomalies and the turbulent and radiative surface heat fluxes. It has been found that both positive and negative feedbacks, which enhance or reduce sea surface temperature anomaly amplitudes, can be generated through changes in the surface boundary layer. Consequent changes in sea surface temperature act to change boundary layer characteristics through changes in static stability or turbulent fluxes. Previous studies over the global oceans have used coarse-resolution observational and model products such as ICOADS and the NCEP Reanalysis. This study focuses on documenting the atmosphere ocean feedbacks that exist in recently produced higher resolution products, namely the SeaFlux v1.0 product and the NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA). It has been noted in recent studies that evidence of oceanic forcing of the atmosphere exists on smaller scales than the usually more dominant atmospheric forcing of the ocean, particularly in higher latitudes. It is expected that use of these higher resolution products will allow for a more comprehensive description of these small-scale ocean-atmosphere feedbacks. The SeaFlux intercomparisons have revealed large scatter between various surface flux climatologies. This study also investigates the uncertainty in surface flux feedbacks based on several of these recent satellite based climatologies

  4. Ocean plankton. Environmental characteristics of Agulhas rings affect interocean plankton transport.

    PubMed

    Villar, Emilie; Farrant, Gregory K; Follows, Michael; Garczarek, Laurence; Speich, Sabrina; Audic, Stéphane; Bittner, Lucie; Blanke, Bruno; Brum, Jennifer R; Brunet, Christophe; Casotti, Raffaella; Chase, Alison; Dolan, John R; d'Ortenzio, Fabrizio; Gattuso, Jean-Pierre; Grima, Nicolas; Guidi, Lionel; Hill, Christopher N; Jahn, Oliver; Jamet, Jean-Louis; Le Goff, Hervé; Lepoivre, Cyrille; Malviya, Shruti; Pelletier, Eric; Romagnan, Jean-Baptiste; Roux, Simon; Santini, Sébastien; Scalco, Eleonora; Schwenck, Sarah M; Tanaka, Atsuko; Testor, Pierre; Vannier, Thomas; Vincent, Flora; Zingone, Adriana; Dimier, Céline; Picheral, Marc; Searson, Sarah; Kandels-Lewis, Stefanie; Acinas, Silvia G; Bork, Peer; Boss, Emmanuel; de Vargas, Colomban; Gorsky, Gabriel; Ogata, Hiroyuki; Pesant, Stéphane; Sullivan, Matthew B; Sunagawa, Shinichi; Wincker, Patrick; Karsenti, Eric; Bowler, Chris; Not, Fabrice; Hingamp, Pascal; Iudicone, Daniele

    2015-05-22

    Agulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic.

  5. Assessment of NPP VIIRS Ocean Color Data Products: Hope and Risk

    NASA Technical Reports Server (NTRS)

    Turpie, Kevin R.; Meister, Gerhard; Eplee, Gene; Barnes, Robert A.; Franz, Bryan; Patt, Frederick S.; Robinson, Wayne d.; McClain, Charles R.

    2010-01-01

    For several years, the NASA/Goddard Space Flight Center (GSFC) NPP VIIRS Ocean Science Team (VOST) provided substantial scientific input to the NPP project regarding the use of Visible Infrared Imaging Radiometer Suite (VIIRS) to create science quality ocean color data products. This work has culminated into an assessment of the NPP project and the VIIRS instrument's capability to produce science quality Ocean Color data products. The VOST concluded that many characteristics were similar to earlier instruments, including SeaWiFS or MODIS Aqua. Though instrument performance and calibration risks do exist, it was concluded that programmatic and algorithm issues dominate concerns. Keywords: NPP, VIIRS, Ocean Color, satellite remote sensing, climate data record.

  6. Hydrates in the Ocean beneath, around, and above Production Equipment

    SciTech Connect

    Anderson, Karl; Bhatnagar, Gaurav; Crosby, Daniel; Hatton, Greg; Manfield, Philip; Kuzmicki, Adam; Fenwick, Nevil; Pontaza, Juan; Wicks, Moye; Socolofsky, Scott; Brady, Cole; Svedeman, Steve; Sum, Amadeu K.; Koh, Carolyn; Levine, Jonathan; Warzinski, Robert P.; Shaffer, Franklin

    2012-07-19

    Hydrates amass beneath and around production equipment and can also form in hydrocarbon-seawater jets and plumes. The sources of hydrocarbons in these hydrates are natural seeps or temporary production system leaks. This paper focuses on two areas: the formation parameters and the impacts on normal production operations and hydrocarbon-spill capture systems.

  7. Redox stabilization of the atmosphere and oceans by phosphorus-limited marine productivity

    PubMed

    Van Cappellen, P; Ingall, E D

    1996-01-26

    Data from modern and ancient marine sediments demonstrate that burial of the limiting nutrient phosphorus is less efficient when bottom waters are low in oxygen. Mass-balance calculations using a coupled model of the biogeochemical cycles of carbon, phosphorus, oxygen, and iron indicate that the redox dependence of phosphorus burial in the oceans provides a powerful forcing mechanism for balancing production and consumption of atmospheric oxygen over geologic time. The oxygen-phosphorus coupling further guards against runaway ocean anoxia. Phosphorus-mediated redox stabilization of the atmosphere and oceans may have been crucial to the radiation of higher life forms during the Phanerozoic.

  8. Possible Factors affecting the Thermal Contrast between Middle-Latitude Asian Continent and Adjacent Ocean

    NASA Astrophysics Data System (ADS)

    Cheng, Huaqiong; Wu, Tongwen; Dong, Wenjie

    2015-04-01

    A middle-latitude Land-Sea thermal contrast Index was used in this study which has close connection to the East Asian summer precipitation. The index has two parts which are land thermal index defined as JJA 500-hPa geopotential height anomalies at a land area (75°-90° E, 40° -55°N ) and ocean thermal index defined as that at an oceanic area (140° -150°E, 35° -42.5°N). The impact of the surface heat flux and atmospheric diabatic heating over the land and the ocean on the index was studied. The results show that the surface heat flux over Eurasian inner land has little influence to the land thermal index, while the variation of the surface latent heat flux and long-wave radiation over the Pacific adjacent to Japan has highly correlation with the ocean thermal index. The changes with height of the atmospheric diabatic heating rates over the Eurasian inner land and the Pacific adjacent to Japan have different features. The variations of the middle troposphere atmospheric long-wave and short-wave radiation heating have significantly influences on land thermal index, and that of the low troposphere atmospheric long-wave radiation, short-wave radiation and deep convective heating also have impact on the yearly variation of the land thermal index. For the ocean thermal index, the variations of the surface layer atmospheric vertical diffuse heating, large-scale latent heating and long-wave radiation heating are more important, low and middle troposphere atmospheric large-scale latent heating and shallow convective heating also have impact on the yearly variation of the ocean thermal index. And then the ocean thermal index has closely connection with the low troposphere atmospheric temperature, while the land thermal index has closely connection with the middle troposphere atmospheric temperature. The Effect of the preceding global SST anomalies on the index also was analyzed. The relations of land thermal index and ocean thermal index and the global SST anomalies

  9. Two MODIS Aerosol Products Over Ocean on the Terra and Aqua CERES SSF Datasets

    NASA Technical Reports Server (NTRS)

    Ignatov, Alexander; Minnis, Patrick; Loeb, Norman; Wielicki, Bruce; Miller, Walter; Sun-Mack, Sunny; Tanre, Didier; Remer, Lorraine; Laszlo, Istvan; Geier, Erika

    2004-01-01

    Over ocean, two aerosol products are reported on the Terra and Aqua CERES SSFs. Both are derived from MODIS, but using different sampling and aerosol algorithms. This study briefly summarizes these products, and compares using 2 weeks of global Terra data from 15-21 December 2000, and 1-7 June 2001.

  10. Enhancing moderate-resolution ocean color products over coastal/inland waters (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pahlevan, Nima; Schott, John R.; Zibordi, Giuseppe

    2016-10-01

    With the successful launch of Landsat-8 in 2013 followed by a very recent launch of Sentinel-2A, we are entering a new area where frequent moderate resolution water quality products over coastal/inland waters will be available to scientists and operational agencies. Although designed for land observations, the Operational Land Imager (OLI) has proven to provide high-fidelity products in these aquatic systems where coarse-resolution ocean color imagers fail to provide valid observations. High-quality, multi-scale ocean color products can give insights into the biogeochemical/physical processes from the upstream in watersheds, into near-shore regions, and further out in ocean basins. In this research, we describe a robust cross-calibration approach, which facilitates seamless ocean color products at multi scales. The top-of-atmosphere (TOA) OLI imagery is cross-calibrated against near-simultaneous MODIS and VIIRS ocean color observations in high-latitude regions. This allows for not only examining the overall relative performance of OLI but also for characterizing non-uniformity (i.e., banding) across its swath. The uncertainty of this approach is, on average, found to be less than 0.5% in the blue channels. The adjustments made for OLI TOA reflectance products are then validated against in-situ measurements of remote sensing reflectance collected in research cruises or at the AERONET-OC.

  11. Assessing the contribution of foraminiferan protists to global ocean carbonate production.

    PubMed

    Langer, Martin R

    2008-01-01

    Larger symbiont-bearing foraminifera are prominent and important producers of calcium carbonate in modern tropical environments. With an estimated production of at least 130 million tons of CaCO(3) per year, they contribute almost 5% of the annual present-day carbonate production in the world's reef and shelf areas (0-200 m) and approximately 2.5% of the CaCO(3) of all oceans. Together with non-symbiont-bearing smaller foraminifera, all benthic foraminifera are estimated to annually produce 200 million tons of calcium carbonate worldwide. The majority of foraminiferal calcite in modern oceans is produced by planktic foraminifera. With an estimated annual production of at least 1.2 billion tons, planktic foraminifera contribute more than 21% of the annual global ocean carbonate production. Total CaCO(3) of benthic and planktic foraminifera together amounts to 1.4 billion tons of calcium carbonate per year. This accounts to almost 25% of the present-day carbonate production of the oceans, and highlights the importance of foraminifera within the CaCO(3) budget of the world's oceans.

  12. Glacial cycles drive variations in the production of oceanic crust

    NASA Astrophysics Data System (ADS)

    Katz, R. F.; Crowley, J. W.; Langmuir, C. H.

    2012-12-01

    Glacial cycles redistribute water between the oceans and continents, causing long-wavelength changes of static pressure in the upper mantle. Previous work has shown that subaerial, glaciated volcanoes respond to these changes with variation in eruption rates (Jull & McKenzie 1996, Huybers & Langmuir 2009), and has suggested that the magmatic flux at mid-ocean ridges may vary with changes in sea-level (Huybers & Langmuir 2009, Lund & Asimow 2011). The latter is speculative, however, because previous theory has assumed highly simplified melt transport and neglected the dependence of the ridge thermal structure on spreading rate. Moreover, it remains a challenge to connect model predictions of variations arising from sea-level change with sea-floor observations. Here we present results from a theoretical model of a mid-ocean ridge based on conservation of mass, momentum, energy, and composition for two phases (magma & mantle) and two thermodynamic components (enriched & depleted) (Katz 2008, 2010). The model is driven by imposed variations in the static pressure within the mantle. We consider both the geochemically inferred record of past sea-level variation, as well as simpler harmonic and instantaneous variations. The output of these models is compared with observations of bathymetry at ridges that are undisturbed by off-axis volcanism. The comparison is preliminary but suggests that some abyssal hills on the sea-floor are, at least in part, the result of glacial cycles. To understand the simulation results in more detail, we develop analytical solutions for a reduced-complexity model. This model is derived according to the idea that the melting induced by sea-level changes can be thought of as a small perturbation to a steady-state system. We obtain a Green's function solution for crustal thickness as a function of sea-level change with the associated dependencies on geophysical parameters of the magma/mantle system. We show that this solution captures much of the

  13. Carbohydrate Production and Consumption In Phytoplankton Subjected To Iron Fertilisation In The Southern Ocean

    NASA Astrophysics Data System (ADS)

    van Oijen, T.; Veldhuis, M. J. W.; van Leeuwe, M. A.; de Baar, H. J. W.

    Iron concentrations in the Southern Ocean are generally low. At these concentrations microalgal growth, in particular of large diatoms, is affected because iron plays a central role in photosynthesis and several metabolic processes. During the Polarstern 2000 iron release experiment, we studied the effect of in situ iron enrichment on the microalgal production and consumption of intracellular carbohydrates. The experi- ment was performed in the Southern Polar Frontal Zone and lasted three weeks. Dur- ing the course of the experiment, discrete samples were taken along vertical profiles (0-100m), both in the centre of the iron enriched patch and outside the patch. In the patch, the particulate carbohydrate concentration had doubled at the end of the exper- iment. An increasing part of the carbohydrates was produced by large diatom cells (>10 micrometer). Outside the patch, little changes were observed. On day 6, 10 and 19 after the release, seawater from inside and outside the patch was incubated on deck for 24h. In all three deck incubations, the diurnal production and nocturnal con- sumption of intracellular carbohydrates by phytoplankton were higher in iron-enriched bottles. Concluding, particulate carbohydrate concentration showed to be a sensitive parameter that clearly responded to iron fertilisation. This study contributes to a bet- ter understanding of factors governing phytoplankton growth in High Nitrogen Low Chlorophyll areas.

  14. A comparison of global estimates of marine primary production from ocean color

    NASA Astrophysics Data System (ADS)

    Carr, Mary-Elena; Friedrichs, Marjorie A. M.; Schmeltz, Marjorie; Noguchi Aita, Maki; Antoine, David; Arrigo, Kevin R.; Asanuma, Ichio; Aumont, Olivier; Barber, Richard; Behrenfeld, Michael; Bidigare, Robert; Buitenhuis, Erik T.; Campbell, Janet; Ciotti, Aurea; Dierssen, Heidi; Dowell, Mark; Dunne, John; Esaias, Wayne; Gentili, Bernard; Gregg, Watson; Groom, Steve; Hoepffner, Nicolas; Ishizaka, Joji; Kameda, Takahiko; Le Quéré, Corinne; Lohrenz, Steven; Marra, John; Mélin, Frédéric; Moore, Keith; Morel, André; Reddy, Tasha E.; Ryan, John; Scardi, Michele; Smyth, Tim; Turpie, Kevin; Tilstone, Gavin; Waters, Kirk; Yamanaka, Yasuhiro

    2006-03-01

    The third primary production algorithm round robin (PPARR3) compares output from 24 models that estimate depth-integrated primary production from satellite measurements of ocean color, as well as seven general circulation models (GCMs) coupled with ecosystem or biogeochemical models. Here we compare the global primary production fields corresponding to eight months of 1998 and 1999 as estimated from common input fields of photosynthetically-available radiation (PAR), sea-surface temperature (SST), mixed-layer depth, and chlorophyll concentration. We also quantify the sensitivity of the ocean-color-based models to perturbations in their input variables. The pair-wise correlation between ocean-color models was used to cluster them into groups or related output, which reflect the regions and environmental conditions under which they respond differently. The groups do not follow model complexity with regards to wavelength or depth dependence, though they are related to the manner in which temperature is used to parameterize photosynthesis. Global average PP varies by a factor of two between models. The models diverged the most for the Southern Ocean, SST under 10C, and chlorophyll concentration exceeding 1 mg Chl m-3. Based on the conditions under which the model results diverge most, we conclude that current ocean-color-based models are challenged by high-nutrient low-chlorophyll conditions, and extreme temperatures or chlorophyll concentrations. The GCM-based models predict comparable primary production to those based on ocean color: they estimate higher values in the Southern Ocean, at low SST, and in the equatorial band, while they estimate lower values in eutrophic regions (probably because the area of high chlorophyll concentrations is smaller in the GCMs). Further progress in primary production modeling requires improved understanding of the effect of temperature on photosynthesis and better parameterization of the maximum photosynthetic rate.

  15. Physical processes affecting availability of dissolved silicate for diatom production in the Arabian Sea

    NASA Technical Reports Server (NTRS)

    Young, David K.; Kindle, John C.

    1994-01-01

    A passive tracer to represent dissolved silicate concentrations, with biologically realistic uptake kinetics, is successfully incorporated into a three-dimensional, eddy-resolving, ocean circulation model of the Indian Ocean. Hypotheses are tested to evaluate physical processes which potentially affect the availability of silicate for diatom production in the Arabian Sea. An alternative mechanism is offered to the idea that open ocean upwelling is primarily responsible for the high, vertical nutrient flux and consequent large-scale phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon. Model results show that dissolved silicate in surface waters available for uptake by diatoms is primarily influenced by the intensity of nearshore upwelling from soutwest monsoonal wind forcing and by the offshore advective transport of surface waters. The upwelling, which in the model occurs within 200 +/- 50 km of the coast, appears to be a result of a combination of coastal upwelling, Elkman pumping, and divergence of the coastal flow as it turns offshore. Localized intensifications of silicate concentrations appear to be hydrodynamically driven and geographically correlated to coastal topographic features. The absence of diatoms in sediments of the eastern Arabian Basin is consistent with modeled distributional patterns of dissolved silicate resulting from limited westward advection of upwelled coastal waters from the western continental margin of India and rapid uptake of available silicate by diatoms. Concentrations of modeled silicate become sufficiently low to become unavailable for diatom production in the eastern Arabian Sea, a region between 61 deg E and 70 deg E at 8 deg N on the south, with the east and west boundaries converging on the north at approximately 67 deg E, 20 deg N.

  16. Marine foods sourced from farther as their use of global ocean primary production increases.

    PubMed

    Watson, Reg A; Nowara, Gabrielle B; Hartmann, Klaas; Green, Bridget S; Tracey, Sean R; Carter, Chris G

    2015-06-16

    The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the world's poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodder-based feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, require an increasing proportion of the ocean's primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the ocean's ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes.

  17. Marine foods sourced from farther as their use of global ocean primary production increases

    PubMed Central

    Watson, Reg A.; Nowara, Gabrielle B.; Hartmann, Klaas; Green, Bridget S.; Tracey, Sean R.; Carter, Chris G.

    2015-01-01

    The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the world's poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodder-based feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, require an increasing proportion of the ocean's primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the ocean's ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes. PMID:26079714

  18. Ocean colour products from geostationary platforms, opportunities with Meteosat Second and Third Generation

    NASA Astrophysics Data System (ADS)

    Kwiatkowska, E. J.; Ruddick, K.; Ramon, D.; Vanhellemont, Q.; Brockmann, C.; Lebreton, C.; Bonekamp, H. G.

    2015-12-01

    Ocean colour applications from medium-resolution polar-orbiting satellite sensors have now matured and evolved into operational services. The examples include the Sentinel-3 OLCI missions of the European Earth Observation Copernicus programme and the VIIRS missions of the US Joint Polar Satellite System programme. Key drivers for Copernicus ocean colour services are the national obligations of the EU member states to report on the quality of marine, coastal and inland waters for the EU Water Framework Directive and Marine Strategy Framework Directive. Further applications include CO2 sequestration, carbon cycle and climate, fisheries and aquaculture management, near-real-time alerting to harmful algae blooms, environmental monitoring and forecasting, and assessment of sediment transport in coastal waters. Ocean colour data from polar-orbiting satellite platforms, however, suffer from fractional coverage, primarily due to clouds, and inadequate resolution of quickly varying processes. Ocean colour remote sensing from geostationary platforms can provide significant improvements in coverage and sampling frequency and support new applications and services. EUMETSAT's SEVIRI instrument on the geostationary Meteosat Second Generation platforms (MSG) is not designed to meet ocean colour mission requirements, however, it has been demonstrated to provide valuable contribution, particularly in combination with dedicated ocean colour polar observations. This paper describes the ongoing effort to develop operational ocean colour water turbidity and related products and user services from SEVIRI. A survey of user requirements and a study of technical capabilities and limitations of the SEVIRI instruments are the basis for this development and are described in this paper. The products will support monitoring of sediment transport, water clarity, and tidal dynamics. Further products and services are anticipated from EUMETSAT's FCI instruments on Meteosat Third Generation

  19. Subsurface Hybrid Power Options for Oil & Gas Production at Deep Ocean Sites

    SciTech Connect

    Farmer, J C; Haut, R; Jahn, G; Goldman, J; Colvin, J; Karpinski, A; Dobley, A; Halfinger, J; Nagley, S; Wolf, K; Shapiro, A; Doucette, P; Hansen, P; Oke, A; Compton, D; Cobb, M; Kopps, R; Chitwood, J; Spence, W; Remacle, P; Noel, C; Vicic, J; Dee, R

    2010-02-19

    An investment in deep-sea (deep-ocean) hybrid power systems may enable certain off-shore oil and gas exploration and production. Advanced deep-ocean drilling and production operations, locally powered, may provide commercial access to oil and gas reserves otherwise inaccessible. Further, subsea generation of electrical power has the potential of featuring a low carbon output resulting in improved environmental conditions. Such technology therefore, enhances the energy security of the United States in a green and environmentally friendly manner. The objective of this study is to evaluate alternatives and recommend equipment to develop into hybrid energy conversion and storage systems for deep ocean operations. Such power systems will be located on the ocean floor and will be used to power offshore oil and gas exploration and production operations. Such power systems will be located on the oceans floor, and will be used to supply oil and gas exploration activities, as well as drilling operations required to harvest petroleum reserves. The following conceptual hybrid systems have been identified as candidates for powering sub-surface oil and gas production operations: (1) PWR = Pressurized-Water Nuclear Reactor + Lead-Acid Battery; (2) FC1 = Line for Surface O{sub 2} + Well Head Gas + Reformer + PEMFC + Lead-Acid & Li-Ion Batteries; (3) FC2 = Stored O2 + Well Head Gas + Reformer + Fuel Cell + Lead-Acid & Li-Ion Batteries; (4) SV1 = Submersible Vehicle + Stored O{sub 2} + Fuel Cell + Lead-Acid & Li-Ion Batteries; (5) SV2 = Submersible Vehicle + Stored O{sub 2} + Engine or Turbine + Lead-Acid & Li-Ion Batteries; (6) SV3 = Submersible Vehicle + Charge at Docking Station + ZEBRA & Li-Ion Batteries; (7) PWR TEG = PWR + Thermoelectric Generator + Lead-Acid Battery; (8) WELL TEG = Thermoelectric Generator + Well Head Waste Heat + Lead-Acid Battery; (9) GRID = Ocean Floor Electrical Grid + Lead-Acid Battery; and (10) DOC = Deep Ocean Current + Lead-Acid Battery.

  20. Are Ferroan Anorthosites Direct Products of the Lunar Magma Ocean?

    NASA Technical Reports Server (NTRS)

    Neal, C. R.; Draper, D. S.

    2016-01-01

    According to Lunar Magma Ocean (LMO) theory, lunar samples that fall into the ferroan anorthosite (FAN) category represent the only samples we have of of the primordial crust of the Moon. Modeling indicates that plagioclase crystallizes after >70% LMO crystallization and formed a flotation crust, depending upon starting composition. The FAN group of highlands materials has been subdivided into mafic-magnesian, mafic-ferroan, anorthositic- sodic, and anorthositic-ferroan, although it is not clear how these subgroups are related. Recent radiogenic isotope work has suggested the range in FAN ages and isotopic systematics are inconsistent with formation of all FANs from the LMO. While an insulating lid could have theoretically extend the life of the LMO to explain the range of the published ages, are the FAN compositions consistent with crystallization from the LMO? As part of a funded Emerging Worlds proposal (NNX15AH76G), we examine this question through analysis of FAN samples. We compare the results with various LMO crystallization models, including those that incorporate the influence of garnet.

  1. Satellite assessment of sea spray aerosol productivity: Southern Ocean case study

    NASA Astrophysics Data System (ADS)

    Witek, Marcin L.; Diner, David J.; Garay, Michael J.

    2016-01-01

    Despite many years of observations by multiple sensors, there is still substantial ambiguity regarding aerosol optical depths (AOD) over remote oceans, in particular, over the pristine Southern Ocean. Passive satellite retrievals (e.g., Multiangle Imaging Spectroradiometer (MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS)) and global aerosol transport models show a distinct AOD maximum around the 60°S latitude band. Sun photometer measurements performed by the Maritime Aerosol Network (MAN), on the other hand, indicate no increased AODs over the Southern Ocean. In this study elevated Southern Ocean AODs are examined from the modeling perspective. The primary aerosol component over the Southern Ocean is sea spray aerosol (SSA). Multiple simulations of SSA concentrations and optical depths are carried out using a single modeling framework, the Navy Aerosol Analysis and Prediction System (NAAPS) model. Several SSA emission functions are examined, including recently proposed formulations with sea surface temperature corrections. The differences between NAAPS simulations are primarily due to different SSA emission formulations. The results are compared against satellite-derived AODs from the MISR and MODIS instruments. MISR and MODIS AOD retrievals are further filtered to eliminate retrievals potentially affected by cloud contamination and cloud adjacency effects. The results indicate a very large impact of SSA emission parameterization on the simulated AODs. For some scenarios, the Southern Ocean AOD maximum almost completely disappears. Further MISR and MODIS AOD quality screening substantially improves model/satellite agreement. Based on these comparisons, an optimal SSA emission function for global aerosol transport models is recommended.

  2. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Holding, J. M.; Duarte, C. M.; Sanz-Martín, M.; Mesa, E.; Arrieta, J. M.; Chierici, M.; Hendriks, I. E.; García-Corral, L. S.; Regaudie-de-Gioux, A.; Delgado, A.; Reigstad, M.; Wassmann, P.; Agustí, S.

    2015-12-01

    The Arctic Ocean is warming at two to three times the global rate and is perceived to be a bellwether for ocean acidification. Increased CO2 concentrations are expected to have a fertilization effect on marine autotrophs, and higher temperatures should lead to increased rates of planktonic primary production. Yet, simultaneous assessment of warming and increased CO2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO2-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range of 145-2,099 μatm however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO2-enhanced primary production has significant implications for metabolic balance in a warmer, CO2-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.

  3. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    PubMed Central

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-01-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity. PMID:27185933

  4. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    NASA Astrophysics Data System (ADS)

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-05-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.

  5. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years.

    PubMed

    Winckler, Gisela; Anderson, Robert F; Jaccard, Samuel L; Marcantonio, Franco

    2016-05-31

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.

  6. Use of coastal zone color scanner imagery to identify nearshore ocean areas affected by land-based pollutants. Final report

    SciTech Connect

    LaPointe, T.F.; Basta, D.J.

    1981-01-01

    The purpose of the analysis was to use remotely sensed satellite imagery to determine the spatial boundaries of nearshore areas or zones likely to be affected by pollutants from land-based sources, so that data collected on the presence or absence of living marine resources could be combined with information on land-based pollutant discharges in a preliminary relative assessment of potential risk. Ocean zones of impact related to East Coast estuaries and embayments were approximated using reflectance patterns from data transmitted from the Coastal Zone Color Scanner (CZCS) instrument mounted on the NASA Nimbus-7 satellite. Data were transformed from numerical measures of radiance to photographic images suitable for identifying and mapping ocean impact zones through a simple enhancement technique.

  7. Global relationship between phytoplankton diversity and productivity in the ocean.

    PubMed

    Vallina, S M; Follows, M J; Dutkiewicz, S; Montoya, J M; Cermeno, P; Loreau, M

    2014-07-01

    The shape of the productivity-diversity relationship (PDR) for marine phytoplankton has been suggested to be unimodal, that is, diversity peaking at intermediate levels of productivity. However, there are few observations and there has been little attempt to understand the mechanisms that would lead to such a shape for planktonic organisms. Here we use a marine ecosystem model together with the community assembly theory to explain the shape of the unimodal PDR we obtain at the global scale. The positive slope from low to intermediate productivity is due to grazer control with selective feeding, which leads to the predator-mediated coexistence of prey. The negative slope at high productivity is due to seasonal blooms of opportunist species that occur before they are regulated by grazers. The negative side is only unveiled when the temporal scale of the observation captures the transient dynamics, which are especially relevant at highly seasonal latitudes. Thus selective predation explains the positive side while transient competitive exclusion explains the negative side of the unimodal PDR curve. The phytoplankton community composition of the positive and negative sides is mostly dominated by slow-growing nutrient specialists and fast-growing nutrient opportunist species, respectively.

  8. Variability of the Black Sea from My Ocean Black Sea Monitoring and Forecasting Center Products

    NASA Astrophysics Data System (ADS)

    Korotaev, G.; Ratner, Yu.; Kholod, A.; Martynov, M.; Ivanchik, M.; Denmyshev, S.; Dorofeev, V.; Knysh, V.; Moiseenko, V.; Kybryakov, A.; Churilova, T.; Suslin, V.

    2012-04-01

    My Ocean project has started provision of the full set of services from 10 January 2012. Regional products in the Black Sea are provided by the Black Sea Marine Forecasting Center (BS MFC). The BS MFC products include operational three-dimensional fields of temperature, salinity, current velocity hindcast, analysis and forecast up to five years (snapshots every three hours or daily averaged fields), reanalysis of the Black Sea dynamics from 1971 to 2002 years, nitrate and phytoplankton daily averaged fields in the upper 200 meter layer and attenuation coefficient analysis. Operational products are simulated by means of assimilation of the sea level anomalies, sea surface temperature and surface chlorophyll concentration, which are products of the Thematic Assembly Centers of My Ocean project, in the models of marine dynamics and ecosystem. Atmospheric forcing for the dynamical model operation is downloaded fro the SKIRON web site. All products are free available in the real-time on the My Ocean project site www.myocean.eu from the My Ocean interactive catalogue in the form of maps on different levels, animations or in digital form. An accuracy of the Black Sea MFC product is estinmated by means fof the comparison of simulations with space remote sensing data or independent in situ measurements by profiling floats or surface drifting buoys. The Black Sea MFC products provide a new insight to the broad range variability of the Black sea dynamics and ecosystem This study is carried out with partial support of the FP6 Sesame project (contract 036949) and FP7 MyOcean project (grant agreement n°218812).

  9. Does word frequency affect lexical selection in speech production?

    PubMed

    Navarrete, Eduardo; Basagni, Benedetta; Alario, F-Xavier; Costa, Albert

    2006-10-01

    We evaluated whether lexical selection in speech production is affected by word frequency by means of two experiments. In Experiment 1 participants named pictures using utterances with the structure "pronoun + verb + adjective". In Experiment 2 participants had to perform a gender decision task on the same pictures. Access to the noun's grammatical gender is needed in both tasks, and therefore lexical selection (lemma retrieval) is required. However, retrieval of the phonological properties (lexeme retrieval) of the referent noun is not needed to perform the tasks. In both experiments we observed faster latencies for high-frequency pictures than for low-frequency pictures. This frequency effect was stable over four repetitions of the stimuli. Our results suggest that lexical selection (lemma retrieval) is sensitive to word frequency. This interpretation runs against the hypothesis that a word's frequency exerts its effects only at the level at which the phonological properties of words are retrieved.

  10. Ocean acidification affects fish spawning but not paternity at CO2 seeps.

    PubMed

    Milazzo, Marco; Cattano, Carlo; Alonzo, Suzanne H; Foggo, Andrew; Gristina, Michele; Rodolfo-Metalpa, Riccardo; Sinopoli, Mauro; Spatafora, Davide; Stiver, Kelly A; Hall-Spencer, Jason M

    2016-07-27

    Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO2 levels. Despite the higher risk of sperm competition found at elevated CO2, we also found a trend of lower satellite and sneaker male paternity at elevated CO2 Given the importance of fish for food security and ecosystem stability, this study highlights the need for targeted research into the effects of rising CO2 levels on patterns of reproduction in wild fish.

  11. Climatic, tectonic, and biological factors affecting the oxidation state of the atmosphere and oceans: Implications for Phanerozoic O2 evolution

    NASA Astrophysics Data System (ADS)

    Ozaki, K.; Tajika, E.

    2015-12-01

    The Earth's atmosphere and oceans have seen fundamental changes in its oxidation state in response to the climatic, tectonic and geochemical variations. Over the past decade, several geochemical proxies have led to significant progress in understanding the paleredox states of ancient oceans. However, a quantitative interpretation of these data for atmospheric O2 levels remain unclear because the relationship between atmospheric O2 levels (pO2) and oceanic redox state depends on several environmental factors, such as terrestrial weathering rate, sea-level stands, and sinking rate of particulate organic matter (POM) in the water column and so on. It is widely thought that the redox-dependent P cycling also plays a crucial role in regulating pO2 because it acts as a negative feedback on a geological timescale. It is important that strength of this feedback for a given pO2 is also modulated by environmental factors, affecting not only O2 levels at steady state but also its susceptibility to environmental changes. In this study, a quantitative role of environmental factors in the oxidation state of Earth's surface environment is evaluated with an oceanic biogeochemical cycle model (CANOPS) coupled with global C cycle model, which enables us to understand the ancient CO2 and O2 evolution. Our results demonstrate that atmospheric O2 level at steady state is affected by CO2 input flux from Earth's interior via changes in biogeochemical cycles, but its response is modulated by several internal factors such as shelf area and POM sinking rate. We also found that early Paleozoic atmospheric O2 levels before the advent of land plant would be determined so that oceans may locate at the "edge of anoxia (EoA)" where the redox-dependency of marine P cycle plays a crucial role in regulating O2 cycle, and that POM sinking rate has a great impact on the EoA. Our findings provide insights into the O2 cycle over the Phanerozoic in response to the climatic and tectonic variations and

  12. Satellites for the study of ocean primary productivity

    NASA Technical Reports Server (NTRS)

    Smith, R. C.; Baker, K. S.

    1983-01-01

    The use of remote sensing techniques for obtaining estimates of global marine primary productivity is examined. It is shown that remote sensing and multiplatform (ship, aircraft, and satellite) sampling strategies can be used to significantly lower the variance in estimates of phytoplankton abundance and of population growth rates from the values obtained using the C-14 method. It is noted that multiplatform sampling strategies are essential to assess the mean and variance of phytoplankton biomass on a regional or on a global basis. The relative errors associated with shipboard and satellite estimates of phytoplankton biomass and primary productivity, as well as the increased statistical accuracy possible from the utilization of contemporaneous data from both sampling platforms, are examined. It is shown to be possible to follow changes in biomass and the distribution patterns of biomass as a function of time with the use of satellite imagery.

  13. Global relationship between phytoplankton diversity and productivity in the ocean

    PubMed Central

    Vallina, S. M.; Follows, M. J.; Dutkiewicz, S.; Montoya, J. M.; Cermeno, P.; Loreau, M.

    2014-01-01

    The shape of the productivity–diversity relationship (PDR) for marine phytoplankton has been suggested to be unimodal, that is, diversity peaking at intermediate levels of productivity. However, there are few observations and there has been little attempt to understand the mechanisms that would lead to such a shape for planktonic organisms. Here we use a marine ecosystem model together with the community assembly theory to explain the shape of the unimodal PDR we obtain at the global scale. The positive slope from low to intermediate productivity is due to grazer control with selective feeding, which leads to the predator-mediated coexistence of prey. The negative slope at high productivity is due to seasonal blooms of opportunist species that occur before they are regulated by grazers. The negative side is only unveiled when the temporal scale of the observation captures the transient dynamics, which are especially relevant at highly seasonal latitudes. Thus selective predation explains the positive side while transient competitive exclusion explains the negative side of the unimodal PDR curve. The phytoplankton community composition of the positive and negative sides is mostly dominated by slow-growing nutrient specialists and fast-growing nutrient opportunist species, respectively. PMID:24980772

  14. Ocean Primary Production Estimates from Terra MODIS and Their Dependency on Satellite Chlorophyll Alpha Algorithms

    NASA Technical Reports Server (NTRS)

    Essias, Wayne E.; Abbott, Mark; Carder, Kendall; Campbell, Janet; Clark, Dennis; Evans, Robert; Brown, Otis; Kearns, Ed; Kilpatrick, Kay; Balch, W.

    2003-01-01

    Simplistic models relating global satellite ocean color, temperature, and light to ocean net primary production (ONPP) are sensitive to the accuracy and limitations of the satellite estimate of chlorophyll and other input fields, as well as the primary productivity model. The standard MODIS ONPP product uses the new semi-analytic chlorophyll algorithm as its input for two ONPP indexes. The three primary MODIS chlorophyll Q estimates from MODIS, as well as the SeaWiFS 4 chlorophyll product, were used to assess global and regional performance in estimating ONPP for the full mission, but concentrating on 2001. The two standard ONPP algorithms were examined with 8-day and 39 kilometer resolution to quantify chlorophyll algorithm dependency of ONPP. Ancillary data (MLD from FNMOC, MODIS SSTD1, and PAR from the GSFC DAO) were identical. The standard MODIS ONPP estimates for annual production in 2001 was 59 and 58 GT C for the two ONPP algorithms. Differences in ONPP using alternate chlorophylls were on the order of 10% for global annual ONPP, but ranged to 100% regionally. On all scales the differences in ONPP were smaller between MODIS and SeaWiFS than between ONPP models, or among chlorophyll algorithms within MODIS. Largest regional ONPP differences were found in the Southern Ocean (SO). In the SO, application of the semi-analytic chlorophyll resulted in not only a magnitude difference in ONPP (2x), but also a temporal shift in the time of maximum production compared to empirical algorithms when summed over standard oceanic areas. The resulting increase in global ONPP (6-7 GT) is supported by better performance of the semi-analytic chlorophyll in the SO and other high chlorophyll regions. The differences are significant in terms of understanding regional differences and dynamics of ocean carbon transformations.

  15. Initial pH of medium affects organic acids production but do not affect phosphate solubilization

    PubMed Central

    Marra, Leandro M.; de Oliveira-Longatti, Silvia M.; Soares, Cláudio R.F.S.; de Lima, José M.; Olivares, Fabio L.; Moreira, Fatima M.S.

    2015-01-01

    The pH of the culture medium directly influences the growth of microorganisms and the chemical processes that they perform. The aim of this study was to assess the influence of the initial pH of the culture medium on the production of 11 low-molecular-weight organic acids and on the solubilization of calcium phosphate by bacteria in growth medium (NBRIP). The following strains isolated from cowpea nodules were studied: UFLA03-08 (Rhizobium tropici), UFLA03-09 (Acinetobacter sp.), UFLA03-10 (Paenibacillus kribbensis), UFLA03-106 (Paenibacillus kribbensis) and UFLA03-116 (Paenibacillus sp.). The strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 solubilized Ca3(PO4)2 in liquid medium regardless of the initial pH, although without a significant difference between the treatments. The production of organic acids by these strains was assessed for all of the initial pH values investigated, and differences between the treatments were observed. Strains UFLA03-09 and UFLA03-10 produced the same acids at different initial pH values in the culture medium. There was no correlation between phosphorus solubilized from Ca3(PO4)2 in NBRIP liquid medium and the concentration of total organic acids at the different initial pH values. Therefore, the initial pH of the culture medium influences the production of organic acids by the strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 but it does not affect calcium phosphate solubilization. PMID:26273251

  16. The CAFE model: A net production model for global ocean phytoplankton

    NASA Astrophysics Data System (ADS)

    Silsbe, Greg M.; Behrenfeld, Michael J.; Halsey, Kimberly H.; Milligan, Allen J.; Westberry, Toby K.

    2016-12-01

    The Carbon, Absorption, and Fluorescence Euphotic-resolving (CAFE) net primary production model is an adaptable framework for advancing global ocean productivity assessments by exploiting state-of-the-art satellite ocean color analyses and addressing key physiological and ecological attributes of phytoplankton. Here we present the first implementation of the CAFE model that incorporates inherent optical properties derived from ocean color measurements into a mechanistic and accurate model of phytoplankton growth rates (μ) and net phytoplankton production (NPP). The CAFE model calculates NPP as the product of energy absorption (QPAR), and the efficiency (ϕμ) by which absorbed energy is converted into carbon biomass (CPhyto), while μ is calculated as NPP normalized to CPhyto. The CAFE model performance is evaluated alongside 21 other NPP models against a spatially robust and globally representative set of direct NPP measurements. This analysis demonstrates that the CAFE model explains the greatest amount of variance and has the lowest model bias relative to other NPP models analyzed with this data set. Global oceanic NPP from the CAFE model (52 Pg C m-2 yr-1) and mean division rates (0.34 day-1) are derived from climatological satellite data (2002-2014). This manuscript discusses and validates individual CAFE model parameters (e.g., QPAR and ϕμ), provides detailed sensitivity analyses, and compares the CAFE model results and parameterization to other widely cited models.

  17. CryoSat Mission over the Ocean: A Review of Product Validations, Evolutions and Scientific Exploitation

    NASA Astrophysics Data System (ADS)

    Bouffard, J.; Abdalla, S.; Bojkov, B.; Calafat, F. M.; Cipollini, P.; Féménias, P.; Leuliette, E. W.; Naeije, M.; Parrinello, T.; Schrama, E. J. O.; Snaith, H. M.; Urien, S.

    2015-12-01

    The main objective of this paper is to present the status of the CryoSat (CS) Mission over the ocean. Launched in 2010, the polar-orbiting CS was primarily developed to measure the changes in the thickness of polar sea ice and the elevation of the ice sheets. Going beyond its ice-monitoring objective, CS is also a valuable source of data for the oceanographic community. The satellite's radar altimeter can indeed measure high resolution Sea-Level Height (SSH), Significant Wave Height (SWH), and Wind Speed (WS) from the open-ocean to the coast. To enable their full scientific and operational exploitation, the CS ocean products continuously evolve and need to be thoroughly validated via science-oriented diagnostics based on in situ data, models and other satellite missions. In support to ESA, the CS ocean validation team (NOCS, ECMWF and TU Delft/DEOS) conjointly conduct these analysis for both the near real time and offline products for the SSH, the SWH, and the WS parameters. The SSH is validated at the coast against sea level measured by a set of carefully selected tide gauges, HF radars and with the help of tools from the Radar Altimetry Database System (RADS). In the open ocean, the SSH is compared globally with the steric heights derived from ARGO temperature and salinity profiles. Near real time WS and SWH are monitored and validated against the corresponding parameters from ECMWF Integrated Forecast System (IFS), the Wavewatch III model, in-situ buoy and platform instruments as well as from other altimetric missions (Jason2 and Saral/AltiKa). Numerical experiments with CS SWH data assimilation have been recently conducted, showing positive impact on ECMWF model analysis and forecasts and leading to the operational assimilation of CS SWH in IFS. Based on the outcomes from these analysis and the scientific exploitations of CS over the ocean, ESA intends to upgrade the CryoSat Ocean processing chain for 2016.

  18. Geophysical evidence for reduced melt production on the Arctic ultraslow Gakkel mid-ocean ridge.

    PubMed

    Jokat, W; Ritzmann, O; Schmidt-Aursch, M C; Drachev, S; Gauger, S; Snow, J

    2003-06-26

    Most models of melt generation beneath mid-ocean ridges predict significant reduction of melt production at ultraslow spreading rates (full spreading rates &<20 mm x yr(-1)) and consequently they predict thinned oceanic crust. The 1,800-km-long Arctic Gakkel mid-ocean ridge is an ideal location to test such models, as it is by far the slowest portion of the global mid-ocean-ridge spreading system, with a full spreading rate ranging from 6 to 13 mm x yr(-1) (refs 4, 5). Furthermore, in contrast to some other ridge systems, the spreading direction on the Gakkel ridge is not oblique and the rift valley is not offset by major transform faults. Here we present seismic evidence for the presence of exceptionally thin crust along the Gakkel ridge rift valley with crustal thicknesses varying between 1.9 and 3.3 km (compared to the more usual value of 7 km found on medium- to fast-spreading mid-ocean ridges). Almost 8,300 km of closely spaced aeromagnetic profiles across the rift valley show the presence of discrete volcanic centres along the ridge, which we interpret as evidence for strongly focused, three-dimensional magma supply. The traces of these eruptive centres can be followed to crustal ages of approximately 25 Myr off-axis, implying that these magma production and transport systems have been stable over this timescale.

  19. Photosynthetic production in the central Arctic Ocean during the record sea-ice minimum in 2012

    NASA Astrophysics Data System (ADS)

    Fernández-Méndez, M.; Katlein, C.; Rabe, B.; Nicolaus, M.; Peeken, I.; Bakker, K.; Flores, H.; Boetius, A.

    2015-06-01

    The ice-covered central Arctic Ocean is characterized by low primary productivity due to light and nutrient limitations. The recent reduction in ice cover has the potential to substantially increase phytoplankton primary production, but little is yet known about the fate of the ice-associated primary production and of the nutrient supply with increasing warming. This study presents results from the central Arctic Ocean collected during summer 2012, when sea-ice extent reached its lowest ever recorded since the onset of satellite observations. Net primary productivity (NPP) was measured in the water column, sea ice and melt ponds by 14CO2 uptake at different irradiances. Photosynthesis vs. irradiance (PI) curves were established in laboratory experiments and used to upscale measured NPP to the deep Eurasian Basin (north of 78° N) using the irradiance-based Central Arctic Ocean Primary Productivity (CAOPP) model. In addition, new annual production has been calculated from the seasonal nutrient drawdown in the mixed layer since last winter. Results show that ice algae can contribute up to 60% to primary production in the central Arctic Ocean at the end of the productive season (August-September). The ice-covered water column has lower NPP rates than open water due to light limitation in late summer. As indicated by the nutrient ratios in the euphotic zone, nitrate was limiting primary production in the deep Eurasian Basin close to the Laptev Sea area, while silicate was the main limiting nutrient at the ice margin near the Atlantic inflow. Although sea-ice cover was substantially reduced in 2012, total annual new production in the Eurasian Basin was 17 ± 7 Tg C yr-1, which is within the range of estimates of previous years. However, when adding the contribution by sub-ice algae, the annual production for the deep Eurasian Basin (north of 78° N) could double previous estimates for that area with a surplus of 16 Tg C yr-1. Our data suggest that sub-ice algae are an

  20. Global and regional drivers of nutrient supply, primary production and CO2 drawdown in the changing Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Éric; Anderson, Leif G.; Matrai, Patricia; Coupel, Pierre; Bélanger, Simon; Michel, Christine; Reigstad, Marit

    2015-12-01

    The main environmental factors driving spatial patterns, variability and change in primary production (PP) in the Arctic Ocean are reviewed. While instantaneous PP rates are predominantly influenced by the local factors affecting light penetration through clouds, sea ice and water, net PP (NPP) at the annual scale is conditioned by a hierarchy of remote and local processes that affect nutrient supply and light availability in general. Nutrient supply sets spatial differences in realized or potential trophic status (i.e. oligotrophic or eutrophic), whereas light availability modulates PP within each regime. Horizontal nutrient supply through Atlantic and Pacific ocean gateways differ markedly, which is explained by their position at opposite ends of the global meridional overturning circulation and imbalanced nitrogen (N) cycling in the Pacific sector. Nutrient supply by rivers is locally important, but does not appear to sustain a major portion of overall pan-Arctic NPP so far. Horizontal nutrient inputs to the surface Arctic Ocean are eventually transferred to the halocline through winter convection and the decomposition of settling organic matter. The subsequent re-injection of these nutrients to the euphotic zone varies by two orders of magnitude across sectors, depending on the strength and persistence of the vertical stratification. Such differences in nutrient delivery are commensurate with those of PP and NPP rates. Widespread N deficiency in surface waters fosters the occurrence and seasonal persistence of subsurface layers of maximum chlorophyll a (SCM) and phytoplankton carbon biomass in several sectors. The contribution of these layers to NPP is possibly higher in the Arctic than in thermally-stratified waters of the subtropical gyres due to a combination of extreme acclimation to low light and a shallow nitracline in the former. The overall impacts of SCM layers on biogeochemical fluxes remain to be quantified directly, both regionally and at the pan

  1. Ocean Acidification Affects Hemocyte Physiology in the Tanner Crab (Chionoecetes bairdi)

    PubMed Central

    Meseck, Shannon L.; Alix, Jennifer H.; Swiney, Katherine M.; Long, W. Christopher; Wikfors, Gary H.; Foy, Robert J.

    2016-01-01

    We used flow cytometry to determine if there would be a difference in hematology, selected immune functions, and hemocyte pH (pHi), under two different, future ocean acidification scenarios (pH = 7.50, 7.80) compared to current conditions (pH = 8.09) for Chionoecetes bairdi, Tanner crab. Hemocytes were analyzed after adult Tanner crabs were held for two years under continuous exposure to acidified ocean water. Total counts of hemocytes did not vary among control and experimental treatments; however, there were significantly greater number of dead, circulating hemocytes in crabs held at the lowest pH treatment. Phagocytosis of fluorescent microbeads by hemocytes was greatest at the lowest pH treatment. These results suggest that hemocytes were dying, likely by apoptosis, at a rate faster than upregulated phagocytosis was able to remove moribund cells from circulation at the lowest pH. Crab hemolymph pH (pHe) averaged 8.09 and did not vary among pH treatments. There was no significant difference in internal pH (pHi) within hyalinocytes among pH treatments and the mean pHi (7.26) was lower than the mean pHe. In contrast, there were significant differences among treatments in pHi of the semi-granular+granular cells. Control crabs had the highest mean semi-granular+granular pHi compared to the lowest pH treatment. As physiological hemocyte functions changed from ambient conditions, interactions with the number of eggs in the second clutch, percentage of viable eggs, and calcium concentration in the adult crab shell was observed. This suggested that the energetic costs of responding to ocean acidification and maintaining defense mechanisms in Tanner crab may divert energy from other physiological processes, such as reproduction. PMID:26859148

  2. Ocean Acidification Affects Hemocyte Physiology in the Tanner Crab (Chionoecetes bairdi).

    PubMed

    Meseck, Shannon L; Alix, Jennifer H; Swiney, Katherine M; Long, W Christopher; Wikfors, Gary H; Foy, Robert J

    2016-01-01

    We used flow cytometry to determine if there would be a difference in hematology, selected immune functions, and hemocyte pH (pHi), under two different, future ocean acidification scenarios (pH = 7.50, 7.80) compared to current conditions (pH = 8.09) for Chionoecetes bairdi, Tanner crab. Hemocytes were analyzed after adult Tanner crabs were held for two years under continuous exposure to acidified ocean water. Total counts of hemocytes did not vary among control and experimental treatments; however, there were significantly greater number of dead, circulating hemocytes in crabs held at the lowest pH treatment. Phagocytosis of fluorescent microbeads by hemocytes was greatest at the lowest pH treatment. These results suggest that hemocytes were dying, likely by apoptosis, at a rate faster than upregulated phagocytosis was able to remove moribund cells from circulation at the lowest pH. Crab hemolymph pH (pHe) averaged 8.09 and did not vary among pH treatments. There was no significant difference in internal pH (pHi) within hyalinocytes among pH treatments and the mean pHi (7.26) was lower than the mean pHe. In contrast, there were significant differences among treatments in pHi of the semi-granular+granular cells. Control crabs had the highest mean semi-granular+granular pHi compared to the lowest pH treatment. As physiological hemocyte functions changed from ambient conditions, interactions with the number of eggs in the second clutch, percentage of viable eggs, and calcium concentration in the adult crab shell was observed. This suggested that the energetic costs of responding to ocean acidification and maintaining defense mechanisms in Tanner crab may divert energy from other physiological processes, such as reproduction.

  3. Effects of ocean acidification on primary production in a coastal North Sea phytoplankton community

    PubMed Central

    Eberlein, Tim; Wohlrab, Sylke; Rost, Björn; John, Uwe; Bach, Lennart T.; Riebesell, Ulf; Van de Waal, Dedmer B.

    2017-01-01

    We studied the effect of ocean acidification (OA) on a coastal North Sea plankton community in a long-term mesocosm CO2-enrichment experiment (BIOACID II long-term mesocosm study). From March to July 2013, 10 mesocosms of 19 m length with a volume of 47.5 to 55.9 m3 were deployed in the Gullmar Fjord, Sweden. CO2 concentrations were enriched in five mesocosms to reach average CO2 partial pressures (pCO2) of 760 μatm. The remaining five mesocosms were used as control at ambient pCO2 of 380 μatm. Our paper is part of a PLOS collection on this long-term mesocosm experiment. Here, we here tested the effect of OA on total primary production (PPT) by performing 14C-based bottle incubations for 24 h. Furthermore, photoacclimation was assessed by conducting 14C-based photosynthesis-irradiance response (P/I) curves. Changes in chlorophyll a concentrations over time were reflected in the development of PPT, and showed higher phytoplankton biomass build-up under OA. We observed two subsequent phytoplankton blooms in all mesocosms, with peaks in PPT around day 33 and day 56. OA had no significant effect on PPT, except for a marginal increase during the second phytoplankton bloom when inorganic nutrients were already depleted. Maximum light use efficiencies and light saturation indices calculated from the P/I curves changed simultaneously in all mesocosms, and suggest that OA did not alter phytoplankton photoacclimation. Despite large variability in time-integrated productivity estimates among replicates, our overall results indicate that coastal phytoplankton communities can be affected by OA at certain times of the seasonal succession with potential consequences for ecosystem functioning. PMID:28273107

  4. Climatic and anthropogenic factors affecting river discharge to the global ocean, 1951-2000

    USGS Publications Warehouse

    Milliman, John D.; Farnsworth, K.L.; Jones, P.D.; Xu, K.H.; Smith, L.C.

    2008-01-01

    During the last half of the 20th century, cumulative annual discharge from 137 representative rivers (watershed areas ranging from 0.3 to 6300 ?? 103??km2) to the global ocean remained constant, although annual discharge from about one-third of these rivers changed by more than 30%. Discharge trends for many rivers reflected mostly changes in precipitation, primarily in response to short- and longer-term atmospheric-oceanic signals; with the notable exception of the Parana, Mississippi, Niger and Cunene rivers, few of these "normal" rivers experienced significant changes in either discharge or precipitation. Cumulative discharge from many mid-latitude rivers, in contrast, decreased by 60%, reflecting in large part impacts due to damming, irrigation and interbasin water transfers. A number of high-latitude and high-altitude rivers experienced increased discharge despite generally declining precipitation. Poorly constrained meteorological and hydrological data do not seem to explain fully these "excess" rivers; changed seasonality in discharge, decreased storage and/or decreased evapotranspiration also may play important roles. ?? 2008 Elsevier B.V. All rights reserved.

  5. Near-Cloud Aerosol Properties from the 1 Km Resolution MODIS Ocean Product

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2014-01-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds-on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550nm AOT changes instantaneous direct aerosol radiative forcing by up to 8W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  6. Near-cloud aerosol properties from the 1 km resolution MODIS ocean product

    NASA Astrophysics Data System (ADS)

    Várnai, Tamás.; Marshak, Alexander

    2014-02-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds—on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550 nm AOT changes instantaneous direct aerosol radiative forcing by up to 8 W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  7. Ocean science. Enhanced: internal tides and ocean mixing.

    PubMed

    Garrett, Chris

    2003-09-26

    Recent satellite and in situ observations have shown that at ocean ridges and other seafloor topographic features, a substantial amount of energy is transferred from the main ocean tides into "internal tides." In his Perspective, Garrett explains how these internal waves with tidal periods propagate through the density-stratified deep ocean and eventually break down into turbulence. The resulting mixing affects ocean stratification and ocean circulation. It thus influences climate as well as biological production. The energy for the internal tides is derived from the rotational energy of the Earth-Moon system changes of the length of the day and the distance to the Moon.

  8. A linkage between Asian dust, dissolved iron and marine export production in the deep ocean

    NASA Astrophysics Data System (ADS)

    Han, Yongxiang; Zhao, Tianliang; Song, Lianchun; Fang, Xiaomin; Yin, Yan; Deng, Zuqin; Wang, Suping; Fan, Shuxian

    2011-08-01

    Iron-addition experiments have revealed that iron supply exerts controls on biogeochemical cycles in the ocean and ultimately influences the Earth's climate system. The iron hypothesis in its broad outlines has been proved to be correct. However, the hypothesis needs to be verified with an observable biological response to specific dust deposition events. Plankton growth following the Asian dust storm over Ocean Station PAPA (50°N, 145°W) in the North Pacific Ocean in April 2001 was the first supportive evidence of natural aeolian iron inputs to ocean; The data were obtained through the SeaWiFS satellite and robot carbon explorers by Bishop et al. Using the NARCM modeling results in this study, the calculated total dust deposition flux was 35 mg m -2 per day in PAPA region from the dust storm of 11-13 April, 2001 into 0.0615 mg m -2 d -1 (about 1100 nM) soluble iron in the surface layer at Station PAPA. It was enough for about 1100 nM to enhance the efficiency of the marine biological pump and trigger the rapid increase of POC and chlorophyll. The iron fertilization hypothesis therefore is plausible. However, even if this specific dust event can support the iron fertilization hypothesis, long-term observation data are lacking in marine export production and continental dust. In this paper, we also conducted a simple correlation analysis between the diatoms and foraminifera at about 3000 m and 4000 m at two subarctic Pacific stations and the dust aerosol production from China's mainland. The correlation coefficient between marine export production and dust storm frequency in the core area of the dust storms was significantly high, suggesting that aerosols generated by Asian dust storm are the source of iron for organic matter fixation in the North Pacific Ocean. These results suggest that there could be an interlocking chain for the change of atmospheric dust aerosol-soluble iron-marine export production.

  9. Oceanic primary production 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll

    NASA Astrophysics Data System (ADS)

    Antoine, David; André, Jean-Michel; Morel, André

    A fast method has been proposed [Antoine and Morel, this issue] to compute the oceanic primary production from the upper ocean chlorophyll-like pigment concentration, as it can be routinely detected by a spaceborne ocean color sensor. This method is applied here to the monthly global maps of the photosynthetic pigments that were derived from the coastal zone color scanner (CZCS) data archive [Feldman et al., 1989]. The photosynthetically active radiation (PAR) field is computed from the astronomical constant and by using an atmospheric model, thereafter combined with averaged cloud information, derived from the International Satellite Cloud Climatology Project (ISCCP). The aim is to assess the seasonal evolution, as well as the spatial distribution of the photosynthetic carbon fixation within the world ocean and for a ``climatological year,'' to the extent that both the chlorophyll information and the cloud coverage statistics actually are averages obtained over several years. The computed global annual production actually ranges between 36.5 and 45.6 Gt C yr-1 according to the assumption which is made (0.8 or 1) about the ratio of active-to-total pigments (recall that chlorophyll and pheopigments are not radiometrically resolved by CZCS). The relative contributions to the global productivity of the various oceans and zonal belts are examined. By considering the hypotheses needed in such computations, the nature of the data used as inputs, and the results of the sensitivity studies, the global numbers have to be cautiously considered. Improving the reliability of the primary production estimates implies (1) new global data sets allowing a higher temporal resolution and a better coverage, (2) progress in the knowledge of physiological responses of phytoplankton and therefore refinements of the time and space dependent parameterizations of these responses.

  10. What causes the inverse relationship between primary production and export efficiency in the Southern Ocean?

    NASA Astrophysics Data System (ADS)

    Le Moigne, Frédéric A. C.; Henson, Stephanie A.; Cavan, Emma; Georges, Clément; Pabortsava, Katsiaryna; Achterberg, Eric P.; Ceballos-Romero, Elena; Zubkov, Mike; Sanders, Richard J.

    2016-05-01

    The ocean contributes to regulating atmospheric CO2 levels, partly via variability in the fraction of primary production (PP) which is exported out of the surface layer (i.e., the e ratio). Southern Ocean studies have found that contrary to global-scale analyses, an inverse relationship exists between e ratio and PP. This relationship remains unexplained, with potential hypotheses being (i) large export of dissolved organic carbon (DOC) in high PP areas, (ii) strong surface microbial recycling in high PP regions, and/or (iii) grazing-mediated export that varies inversely with PP. We find that the export of DOC has a limited influence in setting the negative e ratio/PP relationship. However, we observed that at sites with low PP and high e ratios, zooplankton-mediated export is large and surface microbial abundance low suggesting that both are important drivers of the magnitude of the e ratio in the Southern Ocean.

  11. Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products

    NASA Astrophysics Data System (ADS)

    Karspeck, A. R.; Stammer, D.; Köhl, A.; Danabasoglu, G.; Balmaseda, M.; Smith, D. M.; Fujii, Y.; Zhang, S.; Giese, B.; Tsujino, H.; Rosati, A.

    2015-09-01

    The mean and variability of the Atlantic meridional overturning circulation (AMOC), as represented in six ocean reanalysis products, are analyzed over the period 1960-2007. Particular focus is on multi-decadal trends and interannual variability at 26.5°N and 45°N. For four of the six reanalysis products, corresponding reference simulations obtained from the same models and forcing datasets but without the imposition of subsurface data constraints are included for comparison. An emphasis is placed on identifying general characteristics of the reanalysis representation of AMOC relative to their reference simulations without subsurface data constraints. The AMOC as simulated in these two sets are presented in the context of results from the Coordinated Ocean-ice Reference Experiments phase II (CORE-II) effort, wherein a common interannually varying atmospheric forcing data set was used to force a large and diverse set of global ocean-ice models. Relative to the reference simulations and CORE-II forced model simulations it is shown that (1) the reanalysis products tend to have greater AMOC mean strength and enhanced variance and (2) the reanalysis products are less consistent in their year-to-year AMOC changes. We also find that relative to the reference simulations (but not the CORE-II forced model simulations) the reanalysis products tend to have enhanced multi-decadal trends (from 1975-1995 to 1995-2007) in the mid to high latitudes of the northern hemisphere.

  12. Analysis of Management Behavior Assessments and Affect on Productivity

    DTIC Science & Technology

    2005-06-10

    Analysis of Management Behavior 23 VARIABLES (Behavioral Attributes) Individual and Org. Behavior Individual and Org. Behavor - ILeader’ship...Independent Management Response Affect on Emnployee Beliefs of Management Behavor Manageent Affect Employee Beliefs Sum of Squares df Mean Square F* sig...IncepenteenlMnaemnt Respone Affect on Enployee Beliefs of vknagement Behavor Mamgent Affect FEmployee Beliefs Sum of Squares df Mean Square F* sig

  13. Ocean acidification affects competition for space: projections of community structure using cellular automata

    PubMed Central

    2016-01-01

    Historical ecological datasets from a coastal marine community of crustose coralline algae (CCA) enabled the documentation of ecological changes in this community over 30 years in the Northeast Pacific. Data on competitive interactions obtained from field surveys showed concordance between the 1980s and 2013, yet also revealed a reduction in how strongly species interact. Here, we extend these empirical findings with a cellular automaton model to forecast ecological dynamics. Our model suggests the emergence of a new dominant competitor in a global change scenario, with a reduced role of herbivory pressure, or trophic control, in regulating competition among CCA. Ocean acidification, due to its energetic demands, may now instead play this role in mediating competitive interactions and thereby promote species diversity within this guild. PMID:26936244

  14. Ocean acidification affects competition for space: projections of community structure using cellular automata.

    PubMed

    McCoy, Sophie J; Allesina, Stefano; Pfister, Catherine A

    2016-03-16

    Historical ecological datasets from a coastal marine community of crustose coralline algae (CCA) enabled the documentation of ecological changes in this community over 30 years in the Northeast Pacific. Data on competitive interactions obtained from field surveys showed concordance between the 1980s and 2013, yet also revealed a reduction in how strongly species interact. Here, we extend these empirical findings with a cellular automaton model to forecast ecological dynamics. Our model suggests the emergence of a new dominant competitor in a global change scenario, with a reduced role of herbivory pressure, or trophic control, in regulating competition among CCA. Ocean acidification, due to its energetic demands, may now instead play this role in mediating competitive interactions and thereby promote species diversity within this guild.

  15. Fish Productivity in Open-Ocean Gyre Systems in the Late Oligocene and Miocene

    NASA Astrophysics Data System (ADS)

    Cuevas, J. M.; Sibert, E. C.; Norris, R. D.

    2015-12-01

    Understanding how marine ecosystems respond to climate change is very important as we continue to warm the climate. Fish represent a critical protein source for a significant portion of the global population, and as such, an understanding of fish production and its interactions with climate change may help better prepare for the future. Ichthyoliths, fossil fish teeth and shark scales, are a novel fossil group which can be used as an indicator for fish productivity. Several important climate events occurred during the Miocene (7 to 23 Ma), including the Middle Miocene Climatic Optimum. Here we reconstruct fish production from across the Miocene from Pacific and Atlantic Ocean gyres. South Atlantic samples, from Deep Sea Drilling Program (DSDP) Site 522 spanning from 30 to 20 Ma, show fairly variable numbers in the Oligocene (ranging from 100 to 800 ich/cm2/yr), but stabilization in the Early Miocene (around 400 ich/cm2/yr), suggesting that the beginning of the Miocene brought consistent conditions for fish production. In the North Pacific, our record from Ocean Drilling Program (ODP) Site 886 shows a distinct crash in fish productivity at 11 Ma, from 3500 ich/cm2/yr to a steady decline around 100 ich/cm2/yr for the next million years. This crash is followed by a marked increase in the presence of diatoms and biogenous opal. This is somewhat surprising, since in modern oceanic systems, an increase in diatoms and other large-celled phytoplankton is associated with shorter, more efficient food chains and higher levels of fish. It is also interesting to note that denticles remain consistently low at both sites, indicating consistently low shark populations through this time period. Together, these results suggest that the Late Oligocene and Miocene was a time of variable fish production and provide a window into understanding of dynamic ecosystem changes through the Miocene in open-ocean gyre ecosystems.

  16. Modeling of Geomechanical Performance of Sloping Oceanic Hydrate Deposits Subjected Production Activities

    NASA Astrophysics Data System (ADS)

    Rutqvist, J.; Moridis, G. J.

    2012-12-01

    Oceanic Hydrate-Bearing Sediments (HBS) subjected to production activities can induced strongly coupled fluid flow and geomechanical changes that may have adverse consequences on wellbore integrity, the HBS, and the bounding formations. For a sloping hydrate bearing system, the geomechanical changes could potentially be catastrophic if triggering large slides of the seafloor. Marine sediments adjacent to the seafloor as well as hydrate deposits that are suitable target for production often involves unconsolidated sediments of relatively high porosity that are usually characterized by limited shear strength. The dissociation of the solid hydrates (a strong cementing agent) during gas production can degrade the structural strength of the HBS and thereby undermine the stability of the seafloor. In this study we investigate two cases of coupled hydraulic, thermodynamic and geomechanical behavior of sloping oceanic HBS: 1) hydrate heating as warm fluids from deeper conventional reservoirs ascend to the ocean floor through uninsulated pipes intersecting an HBS adjacent to the seafloor, 2) system response during gas production from a hydrate deposit located 400 m below the seafloor. In the first case we consider a situation when a hydraulically confined hydrate layer near the ocean floor is dissociated by heating from the well with associated gas release and forced pressure increase, which could undermine the stability of the slope. In the second case, depressurization leads to hydrate dissociation over a large lateral distance that may provide a weakening potential slip surface along the sloping hydrate system. The results of our analysis indicate that although these production activities induces strongly coupled geomechanical responses that may adversely impact the production itself, they are unlikely to trigger large scale slides of the seafloor.

  17. Will ocean acidification affect the early ontogeny of a tropical oviparous elasmobranch (Hemiscyllium ocellatum)?

    PubMed Central

    Johnson, Martijn S.; Kraver, Daniel W.; Renshaw, Gillian M. C.; Rummer, Jodie L.

    2016-01-01

    Atmospheric CO2 is increasing due to anthropogenic causes. Approximately 30% of this CO2 is being absorbed by the oceans and is causing ocean acidification (OA). The effects of OA on calcifying organisms are starting to be understood, but less is known about the effects on non-calcifying organisms, notably elasmobranchs. One of the few elasmobranch species that has been studied with respect to OA is the epaulette shark, Hemiscyllium ocellatum. Mature epaulette sharks can physiologically and behaviourally tolerate prolonged exposure to elevated CO2, and this is thought to be because they are routinely exposed to diurnal decreases in O2 and probably concomitant increases in CO2 in their coral reef habitats. It follows that H. ocellatum embryos, while developing in ovo on the reefs, would have to be equally if not more tolerant than adults because they would not be able to escape such conditions. Epaulette shark eggs were exposed to either present-day control conditions (420 µatm) or elevated CO2 (945 µatm) and observed every 3 days from 10 days post-fertilization until 30 days post-hatching. Growth (in square centimetres per day), yolk usage (as a percentage), tail oscillations (per minute), gill movements (per minute) and survival were not significantly different in embryos reared in control conditions when compared with those reared in elevated CO2 conditions. Overall, these findings emphasize the importance of investigating early life-history stages, as the consequences are expected to transfer not only to the success of an individual but also to populations and their distribution patterns. PMID:27293755

  18. Oceanic acidification affects marine carbon pump and triggers extended marine oxygen holes.

    PubMed

    Hofmann, Matthias; Schellnhuber, Hans-Joachim

    2009-03-03

    Rising atmospheric CO(2) levels will not only drive future global mean temperatures toward values unprecedented during the whole Quaternary but will also lead to massive acidification of sea water. This constitutes by itself an anthropogenic planetary-scale perturbation that could significantly modify oceanic biogeochemical fluxes and severely damage marine biota. As a step toward the quantification of such potential impacts, we present here a simulation-model-based assessment of the respective consequences of a business-as-usual fossil-fuel-burning scenario where a total of 4,075 Petagrams of carbon is released into the atmosphere during the current millennium. In our scenario, the atmospheric pCO(2) level peaks at approximately 1,750 microatm in the year 2200 while the sea-surface pH value drops by >0.7 units on global average, inhibiting the growth of marine calcifying organisms. The study focuses on quantifying 3 major concomitant effects. The first one is a significant (climate-stabilizing) negative feedback on rising pCO(2) levels as caused by the attenuation of biogenic calcification. The second one is related to the biological carbon pump. Because mineral ballast, notably CaCO(3), is found to play a dominant role in carrying organic matter through the water column, a reduction of its export fluxes weakens the strength of the biological carbon pump. There is, however, a third effect with severe consequences: Because organic matter is oxidized in shallow waters when mineral-ballast fluxes weaken, oxygen holes (hypoxic zones) start to expand considerably in the oceans in our model world--with potentially harmful impacts on a variety of marine ecosystems.

  19. Evaluation of Global Ocean Data Assimilation Experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model

    NASA Astrophysics Data System (ADS)

    Kourafalou, Vassiliki H.; Peng, Ge; Kang, Heesook; Hogan, Patrick J.; Smedstad, Ole-Martin; Weisberg, Robert H.

    2009-02-01

    The South Florida Hybrid Coordinate Ocean Model (SoFLA-HYCOM) encompasses a variety of coastal regions (the broad Southwest Florida shelf, the narrow Atlantic Keys shelf, the shallow Florida Bay, and Biscayne Bay) and deep regions (the Straits of Florida), including Marine Protected Areas (the Florida Keys Marine Sanctuary and the Dry Tortugas Ecological Reserve). The presence of the strong Loop Current/Florida Current system and associated eddies connects the local and basin-wide dynamics. A multi-nested approach has been developed to ensure resolution of coastal-scale processes and proper interaction with the large scale flows. The simulations are free running and effects of data assimilation are introduced through boundary conditions derived from Global Ocean Data Assimilation Experiment products. The study evaluates the effects of boundary conditions on the successful hindcasting of circulation patterns by a nested model, applied on a dynamically and topographically complex shelf area. Independent (not assimilated) observations are employed for a quantitative validation of the numerical results. The discussion of the prevailing dynamics that are revealed in both modeled and observed patterns suggests the importance of topography resolution and local forcing on the inner shelf to middle shelf areas, while large scale processes are found to dominate the outer shelf flows. The results indicate that the successful hindcasting of circulation patterns in a coastal area that is characterized by complex topography and proximity to a large scale current system requires a dynamical downscaling approach, with simulations that are nested in a hierarchy of data assimilative outer models.

  20. Role of eddy pumping in enhancing primary production in the ocean

    NASA Technical Reports Server (NTRS)

    Falkowski, Paul G.; Kolber, Zbigniew; Ziemann, David; Bienfang, Paul K.

    1991-01-01

    Eddy pumping is considered to explain the disparity between geochemical estimates and biological measurements of exported production. Episodic nutrient injections from the ocean into the photic zone can be generated by eddy pumping, which biological measurements cannot sample accurately. The enhancement of production is studied with respect to a cyclonic eddy in the subtropical Pacific. A pump-and-probe fluorimeter generates continuous vertical profiles of primary productivity from which the contributions of photochemical and nonphotochemical processes to fluorescence are derived. A significant correlation is observed between the fluorescence measurements and radiocarbon measurements. The results indicate that eddy pumping has an important effect on phytoplankton production and that this production is near the maximum relative specific growth rates. Based on the production enhancement observed in this case, eddy pumping increases total primary production by only 20 percent and does not account for all enhancement.

  1. Ocean Products from the SMAP Radiometer: Surface Salinity and Wind Speeds

    NASA Astrophysics Data System (ADS)

    Meissner, T.; Wentz, F. J.; Scott, J. P.

    2015-12-01

    Though designed to measure soil moisture, the SMAP radiometer is an excellent sensor to measure sea surface salinity and sea surface wind speed. It is possible to retrieve both quantities from passive SMAP observations without using the SMAP radar, whose transmitter likely failed in July 2015. With the demise of Aquarius the ability of the SMAP sensor to measure ocean salinity has gained importance. The main part of our presentation discusses the adaption of the Aquarius salinity retrieval algorithm to SMAP. It includes corrections for spurious signals coming from cold space, the galaxy, the sun and the moon as well as sidelobe and cross polarization effects from the SMAP antenna. Based on Aquarius observations, we have developed a radiative transfer model that characterizes the surface emission of a wind roughened ocean. Our surface roughness correction for the SMAP salinity retrieval will use match-ups of SMAP radiometer observations and surface wind speeds from WindSat or SSMIS. Our presentation will also address several important differences between the Aquarius and SMAP sensors that impact the ocean salinity retrievals. The full 360o look capability of SMAP makes it possible to take observations from the forward and backward looking direction basically at the same instance of time. We expect that this two-look capability will strongly aid the salinity retrievals. It will be possible to observe some of the spurious contamination sources like the reflected galaxy or the reflected sun from two different directions. Finally, we will address the capability to measure ocean surface wind speed with the SMAP radiometer. As it has been demonstrated with Aquarius and SMOS the L-band passive ocean surface emission exhibits very good sensitivity to surface wind speeds to at least 35 m/s and it is very little affected by precipitation. This allows the retrieval of ocean surface winds, in particular in storms and even under rainy conditions.

  2. Understanding Oceanic Heavy Precipitation Using Scatterometer, Satellite Precipitation, and Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Garg, Piyush; Nesbitt, Stephen W.; Lang, Timothy J.; Chronis, Themis

    2016-01-01

    The primary aim of this study is to understand the heavy precipitation events over Oceanic regions using vector wind retrievals from space based scatterometers in combination with precipitation products from satellite and model reanalysis products. Heavy precipitation over oceans is a less understood phenomenon and this study tries to fill in the gaps which may lead us to a better understanding of heavy precipitation over oceans. Various phenomenon may lead to intense precipitation viz. MJO (Madden-Julian Oscillation), Extratropical cyclones, MCSs (Mesoscale Convective Systems), that occur inside or outside the tropics and if we can decipher the physical mechanisms behind occurrence of heavy precipitation, then it may lead us to a better understanding of such events which further may help us in building more robust weather and climate models. During a heavy precipitation event, scatterometer wind observations may lead us to understand the governing dynamics behind that event near the surface. We hypothesize that scatterometer winds can observe significant changes in the near-surface circulation and that there are global relationships among these quantities. To the degree to which this hypothesis fails, we will learn about the regional behavior of heavy precipitation-producing systems over the ocean. We use a "precipitation feature" (PF) approach to enable statistical analysis of a large database of raining features.

  3. Corrections to MODIS Terra Calibration and Polarization Trending Derived from Ocean Color Products

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard; Eplee, Robert E.; Franz, Bryan A.

    2014-01-01

    Remotely sensed ocean color products require highly accurate top-of-atmosphere (TOA) radiances, on the order of 0.5% or better. Due to incidents both prelaunch and on-orbit, meeting this requirement has been a consistent problem for the MODIS instrument on the Terra satellite, especially in the later part of the mission. The NASA Ocean Biology Processing Group (OBPG) has developed an approach to correct the TOA radiances of MODIS Terra using spatially and temporally averaged ocean color products from other ocean color sensors (such as the SeaWiFS instrument on Orbview-2 or the MODIS instrument on the Aqua satellite). The latest results suggest that for MODIS Terra, both linear polarization parameters of the Mueller matrix are temporally evolving. A change to the functional form of the scan angle dependence improved the quality of the derived coefficients. Additionally, this paper demonstrates that simultaneously retrieving polarization and gain parameters improves the gain retrieval (versus retrieving the gain parameter only).

  4. Eddies as trigger for diatom productivity in the open-ocean Northeast Atlantic

    NASA Astrophysics Data System (ADS)

    Romero, Oscar E.; Fischer, Gerhard; Karstensen, Johannes; Cermeño, Pedro

    2016-09-01

    Anticyclonic mesoscale eddies (ACME) have been proposed as a mechanism by which new nutrients are episodically delivered into the euphotic zone, thereby enhancing new production as well as shifting phytoplankton community structure. In this paper, we report on a 34-month sediment trap experiment at the Cape Verde Ocean Observatory (CVOO; ca. 18°N, 24°E; December 2009-October 2012), occasionally influenced by ACME passages. The typically oligotrophic, weakly seasonal particle flux pattern at the CVOO is strongly modified by the appearance of a highly productive and low oxygen ACME. Out of four recorded diatom flux maxima at CVOO, three were associated with the passage of ACMEs. The recorded diatom maxima events support the view that local ACME dynamics promotes upward nutrient supply into the euphotic zone leading to a rapid response of diatoms. This response is clearly reflected by the flux seasonality: between 40% and 60% of the total annual diatom flux at the CVOO site was intercepted in a relatively short time interval (<60 days). A highly diverse diatom community characterized the diatom fluxes throughout. Along with the ACME passages, small species of the genus Nitzschia, and Thalassionema nitzschioides var. parva dominated and delivered a major portion of the opal and organic carbon into deeper waters at site CVOO. Several pelagic, warm-water background species became dominant during intervals with low nutrient availability in the euphotic zone. Results of our interannual time-series suggest that ACMEs impact on total diatom production and the species-specific composition of the assemblage north of the Cave Verde Islands, and can strengthen the biological pump in open-ocean, oligotrophic subtropical regions of the world ocean. Our observations are useful for testing biogeochemical ocean models and will also help in improving the knowledge of processes and mechanisms behind interannual time-series of bulk components and microorganisms in pelagic and

  5. Blending remote sensing data products to estimate photochemical production of hydrogen peroxide and superoxide in the surface ocean.

    PubMed

    Powers, Leanne C; Miller, William L

    2014-04-01

    Hydrogen peroxide (H₂O₂) and its precursor, superoxide (O₂(-)), are well-studied photochemical products that are pivotal in regulating redox transformations of trace metals and organic matter in the surface ocean. In attempts to understand the magnitude of both H₂O₂ and O₂(-) photoproduction on a global scale, we implemented a model to calculate photochemical fluxes of these products from remotely sensed ocean color and modeled solar irradiances. We generated monthly climatologies for open ocean H₂O₂ photoproduction rates using an average apparent quantum yield (AQY) spectrum determined from laboratory irradiations of oligotrophic water collected in the Gulf of Alaska. Because the formation of H₂O₂ depends on secondary thermal reactions involving O₂(-), we also implemented a temperature correction for the H₂O₂ AQY using remotely sensed sea surface temperature and an Arrhenius relationship for H₂O₂ photoproduction. Daily photoproduction rates of H₂O₂ ranged from <1 to over 100 nM per day, amounting to ∼30 μM per year in highly productive regions. When production rates were calculated without the temperature correction, maximum daily rates were underestimated by 15-25%, highlighting the importance of including the temperature modification for H₂O₂ in these models. By making assumptions about the relationship between H₂O₂ and O₂(-) photoproduction rates and O₂(-) decay kinetics, we present a method for calculating midday O₂(-) steady-state concentrations ([O₂(-)]ss) in the open ocean. Estimated [O₂(-)]ss ranged from 0.1-5 nM assuming biomolecular dismutation was the only sink for O₂(-), but were reduced to 0.1-290 pM when catalytic pathways were included. While the approach presented here provides the first global scale estimates of marine [O₂(-)]ss from remote sensing, the potential of this model to quantify O₂(-) photoproduction rates and [O₂(-)]ss will not be fully realized until the mechanisms

  6. Future change in ocean productivity: Is the Arctic the new Atlantic?

    NASA Astrophysics Data System (ADS)

    Yool, A.; Popova, E. E.; Coward, A. C.

    2015-12-01

    One of the most characteristic features in ocean productivity is the North Atlantic spring bloom. Responding to seasonal increases in irradiance and stratification, surface phytopopulations rise significantly, a pattern that visibly tracks poleward into summer. While blooms also occur in the Arctic Ocean, they are constrained by the sea-ice and strong vertical stratification that characterize this region. However, Arctic sea-ice is currently declining, and forecasts suggest this may lead to completely ice-free summers by the mid-21st century. Such change may open the Arctic up to Atlantic-style spring blooms, and do so at the same time as Atlantic productivity is threatened by climate change-driven ocean stratification. Here we use low and high-resolution instances of a coupled ocean-biogeochemistry model, NEMO-MEDUSA, to investigate productivity. Drivers of present-day patterns are identified, and changes in these across a climate change scenario (IPCC RCP 8.5) are analyzed. We find a globally significant decline in North Atlantic productivity (> -20%) by 2100, and a correspondingly significant rise in the Arctic (> +50%). However, rather than the future Arctic coming to resemble the current Atlantic, both regions are instead transitioning to a common, low nutrient regime. The North Pacific provides a counterexample where nutrients remain high and productivity increases with elevated temperature. These responses to climate change in the Atlantic and Arctic are common between model resolutions, suggesting an independence from resolution for key impacts. However, some responses, such as those in the North Pacific, differ between the simulations, suggesting the reverse and supporting the drive to more fine-scale resolutions. This article was corrected on 5 JAN 2016. See the end of the full text for details.

  7. Holocene primary productivity and the atmosphere/ocean linkage in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Addison, J. A.; Finney, B.; Anderson, L.; Barron, J. A.; Hayes, S. M.; Sliwinski, M.; Mix, A. C.

    2015-12-01

    Recent work in the temperate fjords of the Gulf of Alaska, located in the subarctic northeast Pacific Ocean, has demonstrated a positive link between modern atmosphere/ocean dynamics and accumulation of biogenic sediments during the last 100 years, where intensified Aleutian Low atmospheric pressure cell regimes correspond to peaks in export primary productivity (Addison et al., 2013). Here, this work is extended by examining the last 7500 years of biogenic sedimentation from marine sediment core EW0408-33JC (57.16°N, 135.36°W, 144 m water depth), which is constrained by 17 age-control points spaced every ~500 years. We use bromine (Br) intensities measured by core-scanning XRF with a 2-mm sampling resolution as a geochemical proxy for past primary productivity. These Br intensities are calibrated to organic Br concentrations using a combination of quantitative WD-XRF methods and synchrotron-radiation Br speciation studies, with cross-verification provided by low-resolution analyses of other productivity proxies, including biogenic silica (opal), total organic carbon (TOC), and organic matter δ13C ratios. Our findings indicate distinct centennial-to-millennial changes, with positive productivity excursions between 7500-7000, 6500-6000, 5000-3500, 2500-1500, and 1000-500 INTCAL13 yr BP. We compare the timing of these excursions against a compilation of marine and terrestrial paleoclimate records sensitive to forcing by the Aleutian Low to determine if the positive relationship between atmosphere/ocean dynamics and marine primary productivity has remained consistent over the last 7500 years. Other potential forcing mechanisms (e.g., solar insolation, irradiance) are also considered. Reference: Addison, J.A., Finney, B., Jaeger, J., Stoner, J., Norris, R., & Hangsterfer, A., 2013, Integrating satellite observations and modern climate measurements with the recent sedimentary record: an example from Southeast Alaska. JGR-Oceans, v. 118, 18 pgs.

  8. Productivity response to the PETM in the North Atlantic and South Indian Ocean

    NASA Astrophysics Data System (ADS)

    Sime, T.; Kanamaru-Shinn, K.; Stoll, H. M.; Shimizu, N.

    2009-12-01

    During the Paleocene Eocene Thermal Maximum (PETM), transient changes in climate and the ocean carbonate system resulted from a major release of isotopically light C into the ocean and atmosphere. We examine the productivity response of calcareous planktonic nannofossils to the dramatic climate and ecosystem changes at DSDP Site 401 in the Bay of Biscay, North Atlantic, and ODP Site 738, Southernmost Indian Ocean. We use the productivity indicator based on Sr/Ca ratios of coccoliths, which is independent of changes in sediment accumulation rate. Sr/Ca is measured in individually picked coccoliths using secondary ion mass spectrometry. At site 401, Sr/Ca ratios in coccoliths of Toweius and Coccolithus pelagicus increase during the PETM, indicating an increase in coccolithophore productivity until the PETM isotope recovery. We are working to characterize the background pre-PETM variability at this site to establish if this increase is a unique response to PETM environmental changes. Bulk sediment Sr/Ca ratios from the same depths, measured by ICP-AES, do not covary with Sr/Ca Coccolithus or Toweius but instead increases monotonically towards shallower depths. One possible explanation is a change in proportion of Sr-poor type coccoliths, such as Discoaster sp. and Zygrhab sp. Stable oxygen and carbon isotopes at site 401 exhibit extremely similar values among three different coccolith size fractions dominated by different genera, consistent with limited vital effects as observed at other sites. At ODP 738, Sr/Ca ratios in Toweius increase during the later part of the PETM and decrease by the end of the recovery, indicating a brief productivity increase. This increase is clearly beyond the background variability before the PETM or during the first part of the CIE. We are assessing whether a similar pattern is observed in Coccolithus. We will also similarly characterize productivity response to ELMO in the Equatorial Pacific and Southernmost Indian Ocean.

  9. Ocean thermal plantships for production of ammonia as the hydrogen carrier.

    SciTech Connect

    Panchal, C.B.; Pandolfini, P. P.; Kumm, W. H.; Energy Systems; Johns Hopkins Univ.; Arctic Energies, Ltd.

    2009-12-02

    Conventional petroleum, natural gas, and coal are the primary sources of energy that have underpinned modern civilization. Their continued availability in the projected quantities required and the impacts of emission of greenhouse gases (GHGs) on the environment are issues at the forefront of world concerns. New primary sources of energy are being sought that would significantly reduce the emissions of GHGs. One such primary source that can help supply energy, water, and fertilizer without GHG emissions is available in the heretofore unexploited thermal gradients of the tropical oceans. The world's oceans are the largest natural collector and reservoir of solar energy. The potential of ocean energy is limitless for producing base-load electric power or ammonia as the hydrogen carrier and fresh water from seawater. However, until now, ocean energy has been virtually untapped. The general perception is that ocean thermal energy is limited to tropical countries. Therefore, the full potential of at-sea production of (1) ammonia as a hydrogen carrier and (2) desalinated water has not been adequately evaluated. Using ocean thermal plantships for the at-sea co-production of ammonia as a hydrogen carrier and desalinated water offer potential energy, environmental, and economic benefits that support the development of the technology. The introduction of a new widespread solution to our projected energy supply requires lead times of a decade or more. Although continuation of the ocean thermal program from the 1970s would likely have put us in a mitigating position in the early 2000s, we still have a window of opportunity to dedicate some of our conventional energy sources to the development of this renewable energy by the time new sources would be critically needed. The primary objective of this project is to evaluate the technical and economic viability of ocean thermal plantships for the production of ammonia as the hydrogen carrier. This objective is achieved by

  10. NASA In Situ Data Needs to Support the Operational Calibration and Validation of Ocean Color Satellite Data Products

    NASA Technical Reports Server (NTRS)

    Werdel, P. Jeremy

    2012-01-01

    Calibrating ocean color satellite instruments and validating their data products requires temporal and spatial abundances of high quality in situ oceanographic data. The Consortium for Ocean Leadership Ocean Observing Initiative (OOl) is currently implementing a distributed array of in-water sensors that could provide a significant contribution to future ocean color activities. This workshop will scope the optimal way to use and possibly supplement the planned OOl infrastructure to maximize its utility and relevance for calibration and validation activities that support existing and planned NASA ocean color missions. Here, I present the current state of the art of NASA validation of ocean color data products, with attention to autonomous time-series (e.g., the AERONET -OC network of above-water radiometers), and outline NASA needs for data quality assurance metrics and adherence to community-vetted data collection protocols

  11. Emotions, affects and the production of social life.

    PubMed

    Fox, Nick J

    2015-06-01

    While many aspects of social life possess an emotional component, sociology needs to explore explicitly the part emotions play in producing the social world and human history. This paper turns away from individualistic and anthropocentric emphases upon the experience of feelings and emotions, attending instead to an exploration of flows of 'affect' (meaning simply a capacity to affect or be affected) between bodies, things, social institutions and abstractions. It establishes a materialist sociology of affects that acknowledges emotions as a part, but only a part, of a more generalized affective flow that produces bodies and the social world. From this perspective, emotions are not a peculiarly remarkable outcome of the confluence of biology and culture, but part of a continuum of affectivity that links human bodies to their physical and social environment. This enhances sociological understanding of the part emotions play in shaping actions and capacities in many settings of sociological concern.

  12. Analytical solution for the vertical profile of daily production in the ocean

    NASA Astrophysics Data System (ADS)

    Kovač, Žarko; Platt, Trevor; Sathyendranath, Shubha; Morović, Mira

    2016-05-01

    Photosynthesis parameters are routinely estimated from in vitro measurements of primary production under constant light reaching each incubation bottle, by fitting a photosynthesis-irradiance function to the measurements. Here we take one such function and integrate it in time for variable light input, similar to natural conditions, to obtain the analytical solution for the vertical profile of daily phytoplankton production in the field. This solution is then fitted to in situ measurements of primary production profiles in the same manner as a photosynthesis-irradiance function is fitted to in vitro measurements under controlled and constant light conditions to retrieve the photosynthesis-irradiance parameters. The method is tested on the Hawaii Ocean Time-series data set. The solution explained 97.88% of the variance in measured normalized production at individual depths. The recovered parameters were then used to model the normalized daily water-column production. The model explained 99.21% of variance in normalized watercolumn production of the entire data set. The seasonal cycle of the photosynthesis parameters recovered with the analytical solution was further studied for the Hawaii Ocean Time-series. With respect to the photosynthesis parameter determination, the solution bridges the gap between classical photosynthesis-irradiance measurements under controlled light conditions and in situ measurements which are made under natural, variable light conditions. It presents a new tool for the estimation of photosynthesis parameters from in situ measurements of primary production.

  13. Interacting effects of ocean acidification and warming on growth and DMS-production in the haptophyte coccolithophore Emiliania huxleyi.

    PubMed

    Arnold, Hayley E; Kerrison, Philip; Steinke, Michael

    2013-04-01

    The production of the marine trace gas dimethyl sulfide (DMS) provides 90% of the marine biogenic sulfur in the atmosphere where it affects cloud formation and climate. The effects of increasing anthropogenic CO2 and the resulting warming and ocean acidification on trace gas production in the oceans are poorly understood. Here we report the first measurements of DMS-production and data on growth, DMSP and DMS concentrations in pH-stated cultures of the phytoplankton haptophyte Emiliania huxleyi. Four different environmental conditions were tested: ambient, elevated CO2 (+CO2 ), elevated temperature (+T) and elevated temperature and CO2 (+TCO2 ). In comparison to the ambient treatment, average DMS production was about 50% lower in the +CO2 treatment. Importantly, temperature had a strong effect on DMS production and the impacts outweighed the effects of a decrease in pH. As a result, the +T and +TCO2 treatments showed significantly higher DMS production of 36.2 ± 2.58 and 31.5 ± 4.66 μmol L(-1) cell volume (CV) h(-1) in comparison with the +CO2 treatment (14.9 ± 4.20 μmol L(-1) CV h(-1) ). As the cultures were aerated with an air/CO2 mixture, DMS was effectively removed from the incubation bottles so that concentration remained relatively low (3.6-6.1 mmol L(-1) CV). Intracellular DMSP has been shown to increase in E. huxleyi as a result of elevated temperature and/or elevated CO2 and our results are in agreement with this finding: the ambient and +CO2 treatments showed 125 ± 20.4 and 162 ± 27.7 mmol L(-1) CV, whereas +T and +TCO2 showed significantly increased intracellular DMSP concentrations of 195 ± 15.8 and 211 ± 28.2 mmol L(-1) CV respectively. Growth was unaffected by the treatments, but cell diameter decreased significantly under elevated temperature. These results indicate that DMS production is sensitive to CO2 and temperature in E. huxleyi. Hence, global environmental change that manifests in ocean acidification and warming may not result in

  14. Validation of Ocean Color Satellite Data Products in Under Sampled Marine Areas. Chapter 6

    NASA Technical Reports Server (NTRS)

    Subramaniam, Ajit; Hood, Raleigh R.; Brown, Christopher W.; Carpenter, Edward J.; Capone, Douglas G.

    2001-01-01

    The planktonic marine cyanobacterium, Trichodesmium sp., is broadly distributed throughout the oligotrophic marine tropical and sub-tropical oceans. Trichodesmium, which typically occurs in macroscopic bundles or colonies, is noteworthy for its ability to form large surface aggregations and to fix dinitrogen gas. The latter is important because primary production supported by N2 fixation can result in a net export of carbon from the surface waters to deep ocean and may therefore play a significant role in the global carbon cycle. However, information on the distribution and density of Trichodesmium from shipboard measurements through the oligotrophic oceans is very sparse. Such estimates are required to quantitatively estimate total global rates of N2 fixation. As a result current global rate estimates are highly uncertain. Thus in order to understand the broader biogeochemical importance of Trichodesmium and N2 fixation in the oceans, we need better methods to estimate the global temporal and spatial variability of this organism. One approach that holds great promise is satellite remote sensing. Satellite ocean color sensors are ideal instruments for estimating global phytoplankton biomass, especially that due to episodic blooms, because they provide relatively high frequency synoptic information over large areas. Trichodesmium has a combination of specific ultrastructural and biochemical features that lend themselves to identification of this organism by remote sensing. Specifically, these features are high backscatter due to the presence of gas vesicles, and absorption and fluorescence of phycoerythrin. The resulting optical signature is relatively unique and should be detectable with satellite ocean color sensors such as the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS).

  15. Changing nutrient stoichiometry affects phytoplankton production, DOP accumulation and dinitrogen fixation - a mesocosm experiment in the eastern tropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Meyer, J.; Löscher, C. R.; Neulinger, S. C.; Reichel, A. F.; Loginova, A.; Borchard, C.; Schmitz, R. A.; Hauss, H.; Kiko, R.; Riebesell, U.

    2016-02-01

    Ocean deoxygenation due to climate change may alter redox-sensitive nutrient cycles in the marine environment. The productive eastern tropical North Atlantic (ETNA) upwelling region may be particularly affected when the relatively moderate oxygen minimum zone (OMZ) deoxygenates further and microbially driven nitrogen (N) loss processes are promoted. Consequently, water masses with a low nitrogen to phosphorus (N : P) ratio could reach the euphotic layer, possibly influencing primary production in those waters. Previous mesocosm studies in the oligotrophic Atlantic Ocean identified nitrate availability as a control of primary production, while a possible co-limitation of nitrate and phosphate could not be ruled out. To better understand the impact of changing N : P ratios on primary production and N2 fixation in the ETNA surface ocean, we conducted land-based mesocosm experiments with natural plankton communities and applied a broad range of N : P ratios (2.67-48). Silicic acid was supplied at 15 µmol L-1 in all mesocosms. We monitored nutrient drawdown, biomass accumulation and nitrogen fixation in response to variable nutrient stoichiometry. Our results confirmed nitrate to be the key factor determining primary production. We found that excess phosphate was channeled through particulate organic matter (POP) into the dissolved organic matter (DOP) pool. In mesocosms with low inorganic phosphate availability, DOP was utilized while N2 fixation increased, suggesting a link between those two processes. Interestingly this observation was most pronounced in mesocosms where nitrate was still available, indicating that bioavailable N does not necessarily suppress N2 fixation. We observed a shift from a mixed cyanobacteria-proteobacteria dominated active diazotrophic community towards a diatom-diazotrophic association of the Richelia-Rhizosolenia symbiosis. We hypothesize that a potential change in nutrient stoichiometry in the ETNA might lead to a general shift within

  16. Simulating oceanic CaCO3 export production in the greenhouse

    NASA Astrophysics Data System (ADS)

    Heinze, C.

    2004-08-01

    A model scenario for the change in global marine biogenic CaCO3 export production (CaCO3 = calcium carbonate) due to increasing atmospheric carbon dioxide partial pressure is carried out. Findings from laboratory experiments, which suggest a decrease of biocalcification at higher pCO2, are extrapolated to the world ocean by use of the biogeochemical ocean general circulation model HAMOCC. For an A1B IPCC emission scenario and constant emission rates after year 2100, the simulation predicts a global decrease of biological CaCO3 export production by about 50% in year 2250. The negative feedback due to this drop in CaCO3 export on the atmospheric CO2 concentration is small as compared to the anthropogenic CO2 emissions. This negative feedback will potentially be compensated by a shallower remineralization of organic carbon.

  17. Benthic macrofaunal production for a typical shelf-slope-basin region in the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Lin, Heshan; Wang, Jianjun; Liu, Kun; He, Xuebao; Lin, Junhui; Huang, Yaqin; Zhang, Shuyi; Mou, Jianfeng; Zheng, Chengxing; Wang, Yu

    2016-02-01

    Secondary production by macrofaunal communities in the western Arctic Ocean were quantified during the 4th and 5th Chinese Arctic Scientific Expeditions. The total production and P/B ratio for each sector ranged from 3.8 (±7.9) to 615.6 (±635.5) kJ m-2 yr-1 and 0.5 (± 0.2) to 0.7 (± 0.2) yr-1, respectively. The shallow shelves in the western Arctic Ocean exhibited particularly high production (178.7-615.6 kJ m-2 yr-1), particularly in the two "hotspots" - the southern and northeastern (around Barrow Canyon) Chukchi Sea. Benthic macrofaunal production decreased sharply with depth and latitude along a shelf-slope-basin transect, with values of 17.0-269.8 kJ m-2 yr-1 in slope regions and 3.8-10.1 kJ m-2 yr-1 in basins. Redundancy analysis indicated that hydrological characteristics (depth, bottom temperature and salinity) and granulometric parameters (mean particle size, % sand and % clay) show significant positive/negative correlations with total production. These correlations revealed that the dominant factors influencing benthic production are the habitat type and food supply from the overlying water column. In the Arctic, the extreme environmental conditions and low temperature constrain macrofaunal metabolic processes, such that food and energy are primarily used to increase body mass rather than for reproduction. Hence, energy turnover is relatively low at high latitudes. These data further our understanding of benthic production processes and ecosystem dynamics in the context of rapid climate change in the western Arctic Ocean.

  18. Factors affecting the distribution of haemosporidian parasites within an oceanic island.

    PubMed

    Padilla, David P; Illera, Juan Carlos; Gonzalez-Quevedo, Catalina; Villalba, Miry; Richardson, David S

    2017-03-01

    Understanding how different ecological and evolutionary processes influence the distribution of pathogens within the environment is important from many perspectives including wildlife epidemiology, evolutionary ecology and conservation. The simultaneous use of ecological and evolutionary frameworks can enhance our conceptual understanding of host-parasite interactions, however such studies are rare in the wild. Using samples from 12 bird species caught across all habitats existing on an oceanic island, we evaluated how environmental variables, parasite host specificity and parasite phylogenetic relationships determine the distribution and prevalence of haemosporidians (Haemoproteus, Plasmodium and Leucocytozoon) in the wild living avifauna. Differences were found in the prevalence of Plasmodium, but not Leucocytozoon, strains between habitats. The warmest temperature best predicted Plasmodium prevalence in the low altitude habitats, which had the highest incidence of Plasmodium. The prevalence of Leucocytozoon lineages was associated with natural factors, i.e. rainfall, temperature and habitat, but the two most important predictors (from model averaging) for models of Leucocytozoon were anthropogenic: poultry farms and distance to a water reservoir. We found no relationship between local (Tenerife, Canary Islands) versus global host range indices (which assess the diversity of hosts that a parasite is observed to infect), thus global generalist lineages do not behave in the same way on Tenerife (i.e. they infected less avian hosts than was expected). Phylogenetic analysis revealed that the most abundant haemosporidians on Tenerife grouped with lineages found in African host species. Our data indicate that climatic and anthropogenic factors, plus proximity to the African mainland, are the main factors influencing the presence and distribution of avian haemosporidians on Tenerife. Future climate projections for the archipelago foresee significant temperature

  19. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean.

    PubMed

    Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-20

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79 °N). Here we present the first central Arctic Ocean (79-90 °N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85 °N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  20. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean

    PubMed Central

    Heimbürger, Lars-Eric; Sonke, Jeroen E.; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T.; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-01-01

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79°N). Here we present the first central Arctic Ocean (79–90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81–85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150–200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production. PMID:25993348

  1. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Heimbürger, Lars-Eric; Sonke, Jeroen E.; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T.; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-01

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79°N). Here we present the first central Arctic Ocean (79-90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  2. Assignment of photosynthetic parameters in estimation of marine phytoplankton production from remote sensing of ocean colour

    NASA Astrophysics Data System (ADS)

    Forget, Marie-Helene

    2007-12-01

    Photosynthesis (primary production) is the fundamental process by which solar photons are transformed into organic matter that is the source of energy for the entire food web. The first chapter of this thesis reviews the concepts that underpin models of marine primary production as well as the relevant parameters and their variation according to phytoplankton functional type. The application of the models to compute primary production from remotely-sensed images of ocean colour is then reviewed. The different approaches for assignment of the photosynthetic parameters in the model are presented and the advantages and disadvantages of each one of them are discussed. Particular emphasis is given to understanding the variability in photosynthesis-irradiance ( P -- E) parameters, which is the focus of the thesis. In Chapter 2 and 4, new measurements of P -- E are presented for two ecologically-different regions of the North Atlantic: the tropical Caribbean waters and the temperate North-West Atlantic. The issues that have to be addressed for regional computations of primary production are examined, and results are presented for primary production in the two regions using remotely-sensed data on ocean colour. Chapter 3 presents a new method for extraction of the photosynthesis-response parameters from profiles of in situ phytoplankton production. The procedure, previously proposed but hitherto untested, is here implemented in various aquatic systems and a protocol is established for its use. The major conclusions and recommendations for future work are presented in the fifth and final chapter.

  3. Net Community Production in the Southern Ocean Monitored with Nitrate and Oxygen Sensors on Profiling Floats

    NASA Astrophysics Data System (ADS)

    Johnson, K. S.; Riser, S.; Swift, D.; Coletti, L.; Jannasch, H. W.; Plant, J.; Sakamoto, C.

    2011-12-01

    The Southern Ocean is the least observed ocean due to its remote location and severe weather. There are few areas visited regularly by ships and surface moorings are difficult to maintain. Profiling floats equipped with biogeochemical sensors provide one mechanism to sustain long term observations in this region. Here we present results obtained from two Apex profiling floats equipped with In Situ Ultraviolet Spectrophotometer (ISUS) nitrate sensors and Aanderaa Optode oxygen sensors. Float 5146 operated for over three years near 55° South in the Indian Ocean sector of the Southern Ocean. It made 230 vertical profiles at 5 day intervals from 1000 m to the surface with 60 nitrate and oxygen measurements on each profile before its batteries were exhausted near the Kerguelen Plateau. Nitrate reported by Float 5146 is shown in the figure. Float 5426 has operated over 2.5 years and made 190 vertical profiles to date. It was initially launched in the near 55° South, 80° West in the Pacific sector and then passed through the Drake Passage and is now near 45° South in the Atlantic sector. Each of these floats provides a unique perspective on changes in net community production along their trajectory. Data quality over the multi-year operating life of each float will first be assessed. Rates of biogeochemical processes that are diagnosed by combining sensor data with a 1-D mixed layer model will then be discussed.

  4. Primary productivity in the southeast Pacific Ocean: Effect of enhanced ultraviolet-B radiation

    SciTech Connect

    Behrenfeld, M. ); Hardy, J.T. ); Gucinski, H.; Wones, A.G. )

    1990-01-09

    Experiments were conducted to determine the effects of predicted increases in solar UV-B radiation, resulting from stratospheric ozone depletion, on the primary production of natural marine phytoplankton assemblages over a wide latitudinal gradient. Primary production was measured every 2 to 4[degrees] latitude in the southeast Pacific using the carbon-14 technique. Fluorescent sunlamps were used to enhance the dose of UV-B radiation above ambient during shipboard incubations. Enhanced UV-B radiation caused a significant mean decrease of 34% in surface water primary production. Decreases in primary production increased with increasing assimilation efficiencies. Results indicate that predicted increases in ambient solar UV-B radiation could result in mean annual decreases of near-surface oceanic primary production of less than 1% near the equator to more than 34% at high southern latitudes.

  5. Discourse Goals Affect the Process and Product of Nominal Metaphor Production.

    PubMed

    Utsumi, Akira; Sakamoto, Maki

    2015-10-01

    Although a large number of studies have addressed metaphor comprehension, only a few attempts have so far been made at exploring the process of metaphor production. Therefore, in this paper, we address the problem of how people generate nominal metaphors or identify an apt vehicle for a given topic of nominal metaphors. Specifically, we examine how the process and product of metaphor production differ between two discourse goals of metaphor, namely an explanatory purpose (e.g., to clarify) and a literary purpose (e.g., to aesthetically pleasing). Experiment 1 analyzed the metaphors (or vehicles) generated in the metaphor production task, and demonstrated that people identified more prototypical exemplars of the property to be attributed to the topic as a vehicle for explanatory metaphors than for literary metaphors. In addition, it was found that metaphors generated for the explanatory purpose were more apt and conventional, and had high topic-vehicle similarity than those generated for the literary purpose, while metaphors generated for the literary purpose were more familiar and imageable than those for the explanatory purpose. Experiment 2 used a priming paradigm to assess the online availability of prototypical and less prototypical members of the topic property during metaphor production. The result was that both prototypical and less prototypical members were activated in producing literary metaphors, while neither members were activated in the production of explanatory metaphors. These findings indicate that the process of metaphor production is affected by discourse goals of metaphor; less prototypical members of the category are searched for a vehicle during the production of literary metaphors, and thus literary metaphors are generated with less prototypical vehicles than explanatory metaphors.

  6. An Inter-calibrated Passive Microwave Brightness Temperature Data Record and Ocean Products

    NASA Astrophysics Data System (ADS)

    Hilburn, K. A.; Wentz, F. J.

    2014-12-01

    Inter-calibration of passive microwave sensors has been the subject of on-going activity at Remote Sensing Systems (RSS) since 1974. RSS has produced a brightness temperature TB data record that spans the last 28 years (1987-2014) from inter-calibrated passive microwave sensors on 14 satellites: AMSR-E, AMSR2, GMI, SSMI F08-F15, SSMIS F16-F18, TMI, WindSat. Accompanying the TB record are a suite of ocean products derived from the TBs that provide a 28-year record of wind speed, water vapor, cloud liquid, and rain rate; and 18 years (1997-2014) of sea surface temperatures, corresponding to the period for which 6 and/or 10 GHz measurements are available. Crucial to the inter-calibration and ocean product retrieval are a highly accurate radiative transfer model RTM. The RSS RTM has been continually refined for over 30 years and is arguably the most accurate model in the 1-100 GHz spectrum. The current generation of TB and ocean products, produced using the latest version of the RTM, is called Version-7. The accuracy of the Version-7 inter-calibration is estimated to be 0.1 K, based on inter-satellite comparisons and validation of the ocean products against in situ measurements. The data record produced by RSS has had a significant scientific impact. Over just the last 14 years (2000-2013) RSS data have been used in 743 peer-reviewed journal articles. This is an average of 4.5 peer-reviewed papers published every month made possible with RSS data. Some of the most important scientific contributions made by RSS data have been to the study of the climate. The AR5 Report "Climate Change 2013: The Physical Science Basis" by the Intergovernmental Panel on Climate Change (IPCC), the internationally accepted authority on climate change, references 20 peer-reviewed journal papers from RSS scientists. The report makes direct use of RSS water vapor data, RSS atmospheric temperatures from MSU/AMSU, and 9 other datasets that are derived from RSS data. The RSS TB data record is

  7. Contribution of Archaea to total prokaryotic production in the deep Atlantic Ocean.

    PubMed

    Herndl, Gerhard J; Reinthaler, Thomas; Teira, Eva; van Aken, Hendrik; Veth, Cornelius; Pernthaler, Annelie; Pernthaler, Jakob

    2005-05-01

    Fluorescence in situ hybridization (FISH) in combination with polynucleotide probes revealed that the two major groups of planktonic Archaea (Crenarchaeota and Euryarchaeota) exhibit a different distribution pattern in the water column of the Pacific subtropical gyre and in the Antarctic Circumpolar Current system. While Euryarchaeota were found to be more dominant in nearsurface waters, Crenarchaeota were relatively more abundant in the mesopelagic and bathypelagic waters. We determined the abundance of archaea in the mesopelagic and bathypelagic North Atlantic along a south-north transect of more than 4,000 km. Using an improved catalyzed reporter deposition-FISH (CARD-FISH) method and specific oligonucleotide probes, we found that archaea were consistently more abundant than bacteria below a 100-m depth. Combining microautoradiography with CARD-FISH revealed a high fraction of metabolically active cells in the deep ocean. Even at a 3,000-m depth, about 16% of the bacteria were taking up leucine. The percentage of Euryarchaeota and Crenarchaeaota taking up leucine did not follow a specific trend, with depths ranging from 6 to 35% and 3 to 18%, respectively. The fraction of Crenarchaeota taking up inorganic carbon increased with depth, while Euryarchaeota taking up inorganic carbon decreased from 200 m to 3,000 m in depth. The ability of archaea to take up inorganic carbon was used as a proxy to estimate archaeal cell production and to compare this archaeal production with total prokaryotic production measured via leucine incorporation. We estimate that archaeal production in the mesopelagic and bathypelagic North Atlantic contributes between 13 to 27% to the total prokaryotic production in the oxygen minimum layer and 41 to 84% in the Labrador Sea Water, declining to 10 to 20% in the North Atlantic Deep Water. Thus, planktonic archaea are actively growing in the dark ocean although at lower growth rates than bacteria and might play a significant role in the

  8. Contribution of Archaea to Total Prokaryotic Production in the Deep Atlantic Ocean

    PubMed Central

    Herndl, Gerhard J.; Reinthaler, Thomas; Teira, Eva; van Aken, Hendrik; Veth, Cornelius; Pernthaler, Annelie; Pernthaler, Jakob

    2005-01-01

    Fluorescence in situ hybridization (FISH) in combination with polynucleotide probes revealed that the two major groups of planktonic Archaea (Crenarchaeota and Euryarchaeota) exhibit a different distribution pattern in the water column of the Pacific subtropical gyre and in the Antarctic Circumpolar Current system. While Euryarchaeota were found to be more dominant in nearsurface waters, Crenarchaeota were relatively more abundant in the mesopelagic and bathypelagic waters. We determined the abundance of archaea in the mesopelagic and bathypelagic North Atlantic along a south-north transect of more than 4,000 km. Using an improved catalyzed reporter deposition-FISH (CARD-FISH) method and specific oligonucleotide probes, we found that archaea were consistently more abundant than bacteria below a 100-m depth. Combining microautoradiography with CARD-FISH revealed a high fraction of metabolically active cells in the deep ocean. Even at a 3,000-m depth, about 16% of the bacteria were taking up leucine. The percentage of Euryarchaeota and Crenarchaeaota taking up leucine did not follow a specific trend, with depths ranging from 6 to 35% and 3 to 18%, respectively. The fraction of Crenarchaeota taking up inorganic carbon increased with depth, while Euryarchaeota taking up inorganic carbon decreased from 200 m to 3,000 m in depth. The ability of archaea to take up inorganic carbon was used as a proxy to estimate archaeal cell production and to compare this archaeal production with total prokaryotic production measured via leucine incorporation. We estimate that archaeal production in the mesopelagic and bathypelagic North Atlantic contributes between 13 to 27% to the total prokaryotic production in the oxygen minimum layer and 41 to 84% in the Labrador Sea Water, declining to 10 to 20% in the North Atlantic Deep Water. Thus, planktonic archaea are actively growing in the dark ocean although at lower growth rates than bacteria and might play a significant role in the

  9. Biological productivity regime and associated N cycling in the vicinity of Kerguelen Island area, Southern Ocean

    NASA Astrophysics Data System (ADS)

    Cavagna, A. J.; Fripiat, F.; Elskens, M.; Dehairs, F.; Mangion, P.; Chirurgien, L.; Closset, I.; Lasbleiz, M.; Flores-Leiva, L.; Cardinal, D.; Leblanc, K.; Fernandez, C.; Lefèvre, D.; Oriol, L.; Blain, S.; Quéguiner, B.

    2014-12-01

    Although the Southern Ocean is considered a High Nutrient Low Chlorophyll area (HNLC), massive and recurrent blooms are observed over and downstream the Kerguelen Plateau. This mosaic of blooms is triggered by a higher iron supply resulting from the interaction between the Antarctic Circumpolar Current and the local bathymetry. Net primary production, N-uptake (NO3- and NH4+), and nitrification rates were measured at 8 stations in austral spring 2011 (October-November) during the KEOPS2 cruise in the Kerguelen area. Iron fertilization stimulates primary production, with integrated net primary production and growth rates much higher in the fertilized areas (up to 315 mmol C m-2 d-1 and up to 0.31 d-1, respectively) compared to the HNLC reference site (12 mmol C m-2 d-1 and 0.06 d-1, respectively). Primary production is mainly sustained by nitrate uptake, with f ratio (corresponding to NO3- uptake/(NO3- uptake + NH4+ uptake)) lying in the upper end of the observations for the Southern Ocean (up to 0.9). Unexpectedly, we report unprecedented rates of nitrification (up to ~3 mmol C m-2 d-1, with ~90% of them <1 mmol C m-2 d-1). It appears that nitrate is assimilated in the upper part of the mixed layer (coinciding with the euphotic layer) and regenerated in the lower parts. We suggest that such high contribution of nitrification to nitrate assimilation is driven by (i) a deep mixed layer, extending well below the euphotic layer, allowing nitrifiers to compete with phytoplankton for the assimilation of ammonium, (ii) extremely high rates of primary production for the Southern Ocean, stimulating the release of dissolved organic matter, and (iii) an efficient food web, allowing the reprocessing of organic N and the retention of nitrogen into the dissolved phase through ammonium, the substrate for nitrification.

  10. Quantitative estimation of surface ocean productivity and bottom water oxygen concentration using benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Loubere, Paul

    1994-10-01

    An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the usemame andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01624, Quantitative estimation of surface oceanproductivity and bottom water concentration using benthicforaminifera, by P. Loubere). Diskette may be ordered from AmericanGeophysical Union, 2000 Florida Avenue, N.W., Washington, DC20009; $15.00. Payment must accompany order.Quantitative estimation of surface ocean productivity and bottom water oxygen concentration with benthic foraminifera was attempted using 70 samples from equatorial and North Pacific surface sediments. These samples come from a well defined depth range in the ocean, between 2200 and 3200 m, so that depth related factors do not interfere with the estimation. Samples were selected so that foraminifera were well preserved in the sediments and temperature and salinity were nearly uniform (T = 1.5° C; S = 34.6‰). The sample set was also assembled so as to minimize the correlation often seen between surface ocean productivity and bottom water oxygen values (r² = 0.23 for prediction purposes in this case). This procedure reduced the chances of spurious results due to correlations between the environmental variables. The samples encompass a range of productivities from about 25 to >300 gC m-2 yr-1, and a bottom water oxygen range from 1.8 to 3.5 ml/L. Benthic foraminiferal assemblages were quantified using the >62 µm fraction of the sediments and 46 taxon categories. MANOVA multivariate regression was used to project the faunal matrix onto the two environmental dimensions using published values for productivity and bottom water oxygen to calibrate this operation. The success of this regression was measured with the multivariate r

  11. Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs

    NASA Astrophysics Data System (ADS)

    Duprat, Luis P. A. M.; Bigg, Grant R.; Wilton, David J.

    2016-03-01

    Primary productivity is enhanced within a few kilometres of icebergs in the Weddell Sea owing to the input of terrigeneous nutrients and trace elements during iceberg melting. However, the influence of giant icebergs, over 18 km in length, on marine primary production in the Southern Ocean is less well studied. Here we present an analysis of 175 satellite images of open ocean colour before and after the passage of 17 giant icebergs between 2003 and 2013. We detect substantially enhanced chlorophyll levels, typically over a radius of at least 4-10 times the iceberg's length, that can persist for more than a month following passage of a giant iceberg. This area of influence is more than an order of magnitude larger than that found for sub-kilometre scale icebergs or in ship-based surveys of giant icebergs. Assuming that carbon export increases by a factor of 5-10 over the area of influence, we estimate that up to a fifth of the Southern Ocean's downward carbon flux originates with giant iceberg fertilization. We suggest that, if giant iceberg calving increases this century as expected, this negative feedback on the carbon cycle may become more important.

  12. Geologic and societal factors affecting the international oceanic transport of aggregate

    USGS Publications Warehouse

    Langer, W.H.

    1995-01-01

    Crushed stone and sand and gravel are the two main sources of natural aggregate, and together comprise approximately half the volume and tonnage of mined material in the United States. Natural aggregate is a bulky, heavy material without special or unique properties, and it is commonly used near its source of production to minimize haulage cost. However, remoteness is no longer an absolute disqualifier for the production of aggregate. Today interstate aggregate routinely is shipped hundreds of kilometers by rail and barge. In addition, during 1992, the United States imported 1,317,000 metric tons of aggregate from Canada and 1,531,000 metric tons from Mexico. A number of ports on the Atlantic Coast and Gulf Coast of the United States receive imports of crushed stone from foreign sources for transport to various parts of the eastern United States. These areas either lack adequate supplies of aggregate or are augmenting their supplies because they have difficulties meeting current demand. These difficulties may include poor stone quality, environmental permitting problems, or transportation. Certain societal and geologic conditions of New York City and Philadelphia along the Atlantic Coast, and Tampa and New Orleans along the Gulf Coast, are discussed to demonstrate the different combinations of issues that contribute to the economic viability of importing crushed stone. ?? 1995 Oxford University Press.

  13. Statistical frequency in perception affects children's lexical production.

    PubMed

    Richtsmeier, Peter T; Gerken, LouAnn; Goffman, Lisa; Hogan, Tiffany

    2009-06-01

    Children's early word production is influenced by the statistical frequency of speech sounds and combinations. Three experiments asked whether this production effect can be explained by a perceptual learning mechanism that is sensitive to word-token frequency and/or variability. Four-year-olds were exposed to nonwords that were either frequent (presented 10 times) or infrequent (presented once). When the frequent nonwords were spoken by the same talker, children showed no significant effect of perceptual frequency on production. When the frequent nonwords were spoken by different talkers, children produced them with fewer errors and shorter latencies. The results implicate token variability in perceptual learning.

  14. Transpiration affects soil CO2 production in a dry grassland

    NASA Astrophysics Data System (ADS)

    Balogh, János; Fóti, Szilvia; Pintér, Krisztina; Burri, Susanne; Eugster, Werner; Papp, Marianna; Nagy, Zoltán

    2014-05-01

    Although soil CO2 efflux can be highly variable on the diel time scale, it is often measured during daytime only. However, to get a full understanding of soil CO2 efflux and its impact on carbon cycle processes, looking at diurnal processes is crucial. Therefore, our aim was to investigate how diel variation in soil CO2 efflux from a dry, sandy grassland in Hungary depends on variations in potential drivers, such as gross primary production (GPP) and evapotranspiration (ET). In order to reach this goal, we combined measurements of CO2 and H2O fluxes by eddy covariance, soil chambers and soil CO2 gradient system. Surface CO2 fluxes were partitioned into the three CO2 production components originating from the three soil layers to clarify the timing and the source of the CO2 within the top 50 cm of the soil. CO2 production rates during the growing season were higher during nighttime than during daytime. This diel course was not only driven by soil temperature and soil moisture, but also by ET. This was shown by changes of ET causing a hysteresis loop in the diel response of CO2 production to soil temperature. CO2 production was coupled to soil temperature at night and during midday (12-14 h), when ET remained relatively constant. However, when ET was changing over time, CO2 production was decoupled from soil temperature. In order to disentangle these effects, we carried out time-lag analyses between CO2 production and efflux residuals after having subtracted the main effects of soil temperature and soil water content from measured CO2 fluxes. The results showed a strong negative correlation between ET rates and residuals of soil CO2 production, and a less strong, but still significantly time-lagged positive correlation between GPP and residuals of soil CO2 production. Thus, we could show that there is a rapid negative response of soil CO2 production rates to transpiration (suggesting CO2 transport in the xylem stream) and a delayed positive response to GPP

  15. Seasonality of oceanic primary production and its interannual variability from 1998 to 2007

    NASA Astrophysics Data System (ADS)

    Brown, Christopher W.; Schollaert Uz, Stephanie; Corliss, Bruce H.

    2014-08-01

    The seasonality of primary productivity plays an important role in nutrient and carbon cycling. We quantify the seasonality of satellite-derived, oceanic net primary production (NPP) and its interannual variability during the first decade of the SeaWiFS mission (1998 to 2007) using a normalized seasonality index (NSI). The NSI, which is based upon production half-time, t(1/2), generally becomes progressively more episodic with increasing latitude in open ocean waters, spanning from a relatively constant rate of primary productivity throughout the year (mean t(1/2) ~5 months) in subtropical waters to more pulsed events (mean t(1/2) ~3 months) in subpolar waters. This relatively gradual, poleward pattern in NSI differs from recent estimates of phytoplankton bloom duration, another measure of seasonality, at lower latitudes (~40°S-40°N). These differences likely reflect the temporal component of production assessed by each metric, with NSI able to more fully capture the irregular nature of production characteristic of waters in this zonal band. The interannual variability in NSI was generally low, with higher variability observed primarily in frontal and seasonal upwelling zones. The influence of the El Niño-Southern Oscillation on this variability was clearly evident, particularly in the equatorial Pacific, where primary productivity was anomalously episodic from the date line east to the coast of South America in 1998. Yearly seasonality and the magnitude of annual production were generally positively correlated at mid-latitudes and negatively correlated at tropical latitudes, particularly in a region bordering the Pacific equatorial divergence. This implies that increases of annual production in the former region are attained over the course of a year by shorter duration but higher magnitude NPP events, while in the latter areas it results from an increased frequency or duration of similar magnitude events. Statistically significant trends in the seasonality

  16. Exploring posttraumatic growth in Tamil children affected by the Indian Ocean Tsunami in 2004.

    PubMed

    Exenberger, Silvia; Ramalingam, Panch; Höfer, Stefan

    2016-10-13

    Few studies explore posttraumatic growth (PTG) in children from Eastern cultures. To help address this gap, the present study examined PTG among 177 South Indian children aged 8-17 years who were affected by the 2004 Tsunami. The study identifies the underlying factor structure of the Tamil version of the Revised Posttraumatic Growth Inventory for Children (PTGI-C-R), and aims to explore the prevalence of PTG, the relationship between distress and growth, and gender and age differences in PTG. The results of the principal component analysis indicated a two-factor structure with an interpersonal and a person-centred dimension of growth. The total scores of the Tamil PTGI-C-R were positively associated with posttraumatic stress symptoms (PTSS) and age. Moreover, there was a significant relationship between age and the person-centred growth subscale. Non-parametric tests found no gender differences in perceived growth. The role of socio-cultural factors on the nature of PTG is discussed.

  17. Global net community production and the putative net heterotrophy of the oligotrophic oceans

    NASA Astrophysics Data System (ADS)

    Westberry, Toby K.; Williams, Peter J. Le B.; Behrenfeld, Michael J.

    2012-12-01

    Reconciling rates of organic carbon export from the euphotic zone with the consumption of organic material in the dark ocean remains one of the major quantitative uncertainties of the ocean carbon cycle. Euphotic zone net community production (NCP) provides one broad constraint on export flux and potential carbon drawdown. However, in vitro measurements of NCP consistently suggest that oligotrophic oceans are net heterotrophic, which is inconsistent with evidence of their carbon export to depth. Further, we have been unable to identify organic inputs on a scale to supplement the purported net heterotrophy. Here, we calculate global NCP rates using empirical relationships between in vitro photosynthesis (P) and respiration (R) and a satellite-based productivity model. A low value for global NCP (˜139 ± 325 Tmol C a-1) is found when a single P versus R (PvR) relation is derived from all in vitro data, with areas of net heterotrophy occupying 52% of the surface ocean. If a set of PvR relationships are instead derived by segregating the in vitro data into broad latitudinal zones associated with differing nutrient dynamics, we find a global NCP distribution in better agreement with independent model estimates of particulate carbon export, except in the 10°-40° latitudinal band where negative NCP values remain. Consistency between NCP and particulate export across all latitudes is achieved by applying a single PvR relationship derived using all in vitro data collected outside the 10°-40° latitudinal band. With this model, global NCP is estimated at ˜781 ± 393 Tmol C a-1 and modeled values at well-characterized field sites are in good agreement with non-incubation based in situ measurements. We infer from our results that in vitro NCP data from oligotrophic sites are too low, and suggest that this error is more likely the result of underestimated photosynthesis than overestimated respiration, although the precise physiological nature of the problem remains to be

  18. Some factors affecting tannase production by Aspergillus niger Van Tieghem

    PubMed Central

    Aboubakr, Hamada A.; El-Sahn, Malak A.; El-Banna, Amr A.

    2013-01-01

    One variable at a time procedure was used to evaluate the effect of qualitative variables on the production of tannase from Aspergillus niger Van Tieghem. These variables including: fermentation technique, agitation condition, tannins source, adding carbohydrates incorporation with tannic acid, nitrogen source type and divalent cations. Submerged fermentation under intermittent shaking gave the highest total tannase activity. Maximum extracellular tannase activity (305 units/50 mL) was attained in medium containing tannic acid as tannins source and sodium nitrate as nitrogen source at 30 °C for 96 h. All added carbohydrates showed significant adverse effects on the production of tannase. All tested divalent cations significantly decreased tannase production. Moreover, split plot design was carried out to study the effect of fermentation temperature and fermentation time on tannase production. The results indicated maximum tannase production (312.7 units/50 mL) at 35 °C for 96 h. In other words, increasing fermentation temperature from 30 °C to 35 °C resulted in increasing tannase production. PMID:24294255

  19. Some factors affecting tannase production by Aspergillus niger Van Tieghem.

    PubMed

    Aboubakr, Hamada A; El-Sahn, Malak A; El-Banna, Amr A

    2013-01-01

    One variable at a time procedure was used to evaluate the effect of qualitative variables on the production of tannase from Aspergillus niger Van Tieghem. These variables including: fermentation technique, agitation condition, tannins source, adding carbohydrates incorporation with tannic acid, nitrogen source type and divalent cations. Submerged fermentation under intermittent shaking gave the highest total tannase activity. Maximum extracellular tannase activity (305 units/50 mL) was attained in medium containing tannic acid as tannins source and sodium nitrate as nitrogen source at 30 °C for 96 h. All added carbohydrates showed significant adverse effects on the production of tannase. All tested divalent cations significantly decreased tannase production. Moreover, split plot design was carried out to study the effect of fermentation temperature and fermentation time on tannase production. The results indicated maximum tannase production (312.7 units/50 mL) at 35 °C for 96 h. In other words, increasing fermentation temperature from 30 °C to 35 °C resulted in increasing tannase production.

  20. Effects of sea ice cover on satellite-detected primary production in the Arctic Ocean.

    PubMed

    Kahru, Mati; Lee, Zhongping; Mitchell, B Greg; Nevison, Cynthia D

    2016-11-01

    The influence of decreasing Arctic sea ice on net primary production (NPP) in the Arctic Ocean has been considered in multiple publications but is not well constrained owing to the potentially large errors in satellite algorithms. In particular, the Arctic Ocean is rich in coloured dissolved organic matter (CDOM) that interferes in the detection of chlorophyll a concentration of the standard algorithm, which is the primary input to NPP models. We used the quasi-analytic algorithm (Lee et al 2002 Appl. Opti. 41, 5755-5772. (doi:10.1364/AO.41.005755)) that separates absorption by phytoplankton from absorption by CDOM and detrital matter. We merged satellite data from multiple satellite sensors and created a 19 year time series (1997-2015) of NPP. During this period, both the estimated annual total and the summer monthly maximum pan-Arctic NPP increased by about 47%. Positive monthly anomalies in NPP are highly correlated with positive anomalies in open water area during the summer months. Following the earlier ice retreat, the start of the high-productivity season has become earlier, e.g. at a mean rate of -3.0 d yr(-1) in the northern Barents Sea, and the length of the high-productivity period has increased from 15 days in 1998 to 62 days in 2015. While in some areas, the termination of the productive season has been extended, owing to delayed ice formation, the termination has also become earlier in other areas, likely owing to limited nutrients.

  1. The EUMETSAT ocean and sea ice SAF (OSI SAF) : Overview on the project and the products

    NASA Astrophysics Data System (ADS)

    Guevel, Guenole

    The EUMETSAT OSI SAF (www.osi-saf.org) was created in 1997 as an answer to requirements for a comprehensive information derived from meteorological satellites at the ocean-atmosphere interface. The OSI SAF consortium is constituted of Météo-France as leading entity, and Met.no (Norske ee Meteorologiske Institutt), DMI (Danish Meteorological Institute), SMHI (Swedish Meteorolog-ical and Hydrological Institute), KNMI (Koninklijk Nederlands Meteorologisch Instituut) and IFREMER (Institut Français de Recherche pour l'Exploitation de la MER) as co-operating c entities. The two previous phases of the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF), the Development phase (1997-2002) and the IOP (initial Operations Phase, 2002-2007) met the main target which was to develop, validate and then produce operationally quality controlled satellite-derived products related to four key parameters of the sea surface (Sea Surface Temperature, Radiative Fluxes, Sea Ice, Wind) over various geographical coverage from regional to global. These products are currently available in near real time both through EUMETCAST and local FTP servers, and off line from local archive. Archiving at EUMETSAT Data Center is also being implemented. The current phase of the EUMETSAT OSI SAF, the CDOP (Continuous Development and Operations Phase, 2007-2012) has taken into account new requirements expressed in particular in the context of GODAE, GHRSST and GCOS at international level, and GMES (through MyOcean) at European level, with in particular a strong need for increasing the temporal and geographical resolution of the products and user friendly interfaces allowing access to high level allowing flexible extraction An overview on the OSI SAF project and its current and future production in the time frame of the CDOP will be presented, as well as first glance on the following phase, the CDOP-2, that will cover 2012 to 2017.

  2. Drivers of trophic amplification of ocean productivity trends in a changing climate

    NASA Astrophysics Data System (ADS)

    Stock, C. A.; Dunne, J. P.; John, J. G.

    2014-12-01

    Pronounced projected 21st century trends in regional oceanic net primary production (NPP) raise the prospect of significant redistributions of marine resources. Recent results further suggest that NPP changes may be amplified at higher trophic levels. Here, we elucidate the role of planktonic food web dynamics in driving projected changes in mesozooplankton production (MESOZP) found to be, on average, twice as large as projected changes in NPP by the latter half of the 21st century under a high emissions scenario in the Geophysical Fluid Dynamics Laboratory's ESM2M-COBALT (Carbon, Ocean Biogeochemistry and Lower Trophics) earth system model. Globally, MESOZP was projected to decline by 7.9% but regional MESOZP changes sometimes exceeded 50%. Changes in three planktonic food web properties - zooplankton growth efficiency (ZGE), the trophic level of mesozooplankton (MESOTL), and the fraction of NPP consumed by zooplankton (zooplankton-phytoplankton coupling, ZPC), explain the projected amplification. Zooplankton growth efficiencies (ZGE) changed with NPP, amplifying both NPP increases and decreases. Negative amplification (i.e., exacerbation) of projected subtropical NPP declines via this mechanism was particularly strong since consumers in the subtropics have limited surplus energy above basal metabolic costs. Increased mesozooplankton trophic level (MESOTL) resulted from projected declines in large phytoplankton production. This further amplified negative subtropical NPP declines but was secondary to ZGE and, at higher latitudes, was often offset by increased ZPC. Marked ZPC increases were projected for high-latitude regions experiencing shoaling of deep winter mixing or decreased winter sea ice - both tending to increase winter zooplankton biomass and enhance grazer control of spring blooms. Increased ZPC amplified projected NPP increases in the Arctic and damped projected NPP declines in the northwestern Atlantic and Southern Ocean. Improved understanding of the

  3. Temperature can interact with landscape factors to affect songbird productivity.

    PubMed

    Cox, W Andrew; Thompson, Frank R; Reidy, Jennifer L; Faaborg, John

    2013-04-01

    Increased temperatures and more extreme weather patterns associated with global climate change can interact with other factors that regulate animal populations, but many climate change studies do not incorporate other threats to wildlife in their analyses. We used 20 years of nest-monitoring data from study sites across a gradient of habitat fragmentation in Missouri, USA, to investigate the relative influence of weather variables (temperature and precipitation) and landscape factors (forest cover and edge density) on the number of young produced per nest attempt (i.e., productivity) for three species of songbirds. We detected a strong forest cover × temperature interaction for the Acadian Flycatcher (Empidonax virescens) on productivity. Greater forest cover resulted in greater productivity because of reduced brood parasitism and increased nest survival, whereas greater temperatures reduced productivity in highly forested landscapes because of increased nest predation but had no effect in less forested landscapes. The Indigo Bunting (Passerina cyanea) exhibited a similar pattern, albeit with a marginal forest cover × temperature interaction. By contrast, productivity of the Northern Cardinal (Cardinalis cardinalis) was not influenced by landscape effects or temperature. Our results highlight a potential difficulty of managing wildlife in response to global change such as habitat fragmentation and climate warming, as the habitat associated with the greatest productivity for flycatchers was also that most negatively influenced by high temperatures. The influence of high temperatures on nest predation (and therefore, nest predators) underscores the need to acknowledge the potential complexity of species' responses to climate change by incorporating a more thorough consideration of community ecology in the development of models of climate impacts on wildlife.

  4. Arctic Ocean Atmosphere Sea Ice Snowpack (OASIS) Interactions Affecting Atmospheric Biogeochemistry, Climate and Ecosystems in the Arctic

    NASA Astrophysics Data System (ADS)

    Beine, H.

    2006-12-01

    The Arctic Ocean is central to the understanding of climate and global environmental change. As a critical component of the Earth system, the Arctic region both influences and responds rapidly to natural variations and to human-induced perturbations, such as warming, contaminant accumulation, and associated impacts. While it is clear that there are dramatic changes occurring in the Arctic, the interactions between the air and surfaces are still not understood. The international, multidisciplinary Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) program addresses the knowledge gaps and coordinates studies of Arctic atmosphere-surface interactions and associated feedbacks to the climate system. OASIS is planned as a long term science program for the next decade. OASIS is linked to a number of international organizations and activities, including AMAP, the IGBP programs IGAC under the AICI (Air Ice Chemical Interactions) activity, and SOLAS (Surface Ocean Lower Atmosphere Study), and the WCRP project CliC (Climate and Cryosphere). The abundant snowpack in the Arctic is not just a white cover: an array of intriguing reactions has been observed within and on snowpacks and sea-ice during springtime Arctic sunrise that dramatically influences the composition of the atmosphere. Building on these discoveries, the OASIS research approach is aimed at a better understanding of air-surface chemical exchange in the context of a changing climate. Fundamental physical, chemical, and biologically-mediated chemical exchange processes will be studied to answer questions such as: Will climate change increase or decrease the amount of mercury deposited in the Arctic? How will warming affect regional and global climate? How are sea ice and snow chemistry and physics changing? What is the role of biological processes in producing reactive atmospheric gases? What is the role of sea-salt in ozone depletion? What are ecological and human health impacts of toxic materials such as mercury and

  5. Gas production potential of disperse low-saturation hydrateaccumulations in oceanic sediments

    SciTech Connect

    Moridis, George J.; Sloan, E. Dendy

    2006-07-19

    In this paper we evaluate the gas production potential ofdisperse, low-saturation (SH<0.1) hydrate accumulations in oceanicsediments. Such hydrate-bearing sediments constitute a significantportion of the global hydrate inventory. Using numerical simulation, weestimate (a) the rates of gas production and gas release from hydratedissociation, (b) the corresponding cumulative volumes of released andproduced gas, as well as (c) the water production rate and the mass ofproduced water from disperse, low-SH hydrate-bearing sediments subject todepressurization-induced dissociation over a 10-year production period.We investigate the sensitivity of items (a) to (c) to the followinghydraulic properties, reservoir conditions, and operational parameters:intrinsic permeability, porosity, pressure, temperature, hydratesaturation, and constant pressure at which the production well is kept.The results of this study indicate that, despite wide variations in theaforementioned parameters (covering the entire spectrum of suchdeposits), gas production is very limited, never exceeding a few thousandcubic meters of gas during the 10-year production period. Such lowproduction volumes are orders of magnitude below commonly acceptedstandards of economic viability, and are further burdened with veryunfavorable gas-to-water ratios. The unequivocal conclusion from thisstudy is that disperse, low-SH hydrate accumulations in oceanic sedimentsare not promising targets for gas production by means ofdepressurization-induced dissociation, and resources for early hydrateexploitation should be focused elsewhere.

  6. Sex of littermate twin affects lifetime ewe productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ewe productivity is synonymous with annual litter-weight weaned (LWW) per ewe exposed to rams for breeding, and LWW is largely a function of number of lambs born (NLB) and weaned (NLW). Selecting for LWW should increase litter size and numbers of ewe-ram co-twins. Thus, we used historical records to...

  7. Affected functional networks associated with sentence production in classic galactosemia.

    PubMed

    Timmers, Inge; van den Hurk, Job; Hofman, Paul Am; Zimmermann, Luc Ji; Uludağ, Kâmil; Jansma, Bernadette M; Rubio-Gozalbo, M Estela

    2015-08-07

    Patients with the inherited metabolic disorder classic galactosemia have language production impairments in several planning stages. Here, we assessed potential deviations in recruitment and connectivity across brain areas responsible for language production that may explain these deficits. We used functional magnetic resonance imaging (fMRI) to study neural activity and connectivity while participants carried out a language production task. This study included 13 adolescent patients and 13 age- and gender-matched healthy controls. Participants passively watched or actively described an animated visual scene using two conditions, varying in syntactic complexity (single words versus a sentence). Results showed that patients recruited additional and more extensive brain regions during sentence production. Both groups showed modulations with syntactic complexity in left inferior frontal gyrus (IFG), a region associated with syntactic planning, and in right insula. In addition, patients showed a modulation with syntax in left superior temporal gyrus (STG), whereas the controls did not. Further, patients showed increased activity in right STG and right supplementary motor area (SMA). The functional connectivity data showed similar patterns, with more extensive connectivity with frontal and motor regions, and restricted and weaker connectivity with superior temporal regions. Patients also showed higher baseline cerebral blood flow (CBF) in right IFG and trends towards higher CBF in bilateral STG, SMA and the insula. Taken together, the data demonstrate that language abnormalities in classic galactosemia are associated with specific changes within the language network. These changes point towards impairments related to both syntactic planning and speech motor planning in these patients.

  8. Monitoring and Predicting the Export and Fate of Global Ocean Net Primary Production: The EXPORTS Field Program

    NASA Astrophysics Data System (ADS)

    Exports Science Definition Team

    2016-04-01

    Ocean ecosystems play a critical role in the Earth's carbon cycle and its quantification on global scales remains one of the greatest challenges in global ocean biogeochemistry. The goal of the EXport Processes in the Ocean from Remote Sensing (EXPORTS) science plan is to develop a predictive understanding of the export and fate of global ocean primary production and its implications for the Earth's carbon cycle in present and future climates. NASA's satellite ocean-color data record has revolutionized our understanding of global marine systems. EXPORTS is designed to advance the utility of NASA ocean color assets to predict how changes in ocean primary production will impact the global carbon cycle. EXPORTS will create a predictive understanding of both the export of organic carbon from the euphotic zone and its fate in the underlying "twilight zone" (depths of 500 m or more) where variable fractions of exported organic carbon are respired back to CO2. Ultimately, it is the sequestration of deep organic carbon transport that defines the impact of ocean biota on atmospheric CO2 levels and hence climate. EXPORTS will generate a new, detailed understanding of ocean carbon transport processes and pathways linking upper ocean phytoplankton processes to the export and fate of organic matter in the underlying twilight zone using a combination of field campaigns, remote sensing and numerical modeling. The overarching objective for EXPORTS is to ensure the success of future satellite missions by establishing mechanistic relationships between remotely sensed signals and carbon cycle processes. Through a process-oriented approach, EXPORTS will foster new insights on ocean carbon cycling that will maximize its societal relevance and be a key component in the U.S. investment to understand Earth as an integrated system.

  9. Quantifying melt production and degassing rate at mid-ocean ridges from global mantle convection models with plate motion history

    NASA Astrophysics Data System (ADS)

    Li, Mingming; Black, Benjamin; Zhong, Shijie; Manga, Michael; Rudolph, Maxwell L.; Olson, Peter

    2016-07-01

    The Earth's surface volcanism exerts first-order controls on the composition of the atmosphere and the climate. On Earth, the majority of surface volcanism occurs at mid-ocean ridges. In this study, based on the dependence of melt fraction on temperature, pressure, and composition, we compute melt production and degassing rate at mid-ocean ridges from three-dimensional global mantle convection models with plate motion history as the surface velocity boundary condition. By incorporating melting in global mantle convection models, we connect deep mantle convection to surface volcanism, with deep and shallow mantle processes internally consistent. We compare two methods to compute melt production: a tracer method and an Eulerian method. Our results show that melt production at mid-ocean ridges is mainly controlled by surface plate motion history, and that changes in plate tectonic motion, including plate reorganizations, may lead to significant deviation of melt production from the expected scaling with seafloor production rate. We also find a good correlation between melt production and degassing rate beneath mid-ocean ridges. The calculated global melt production and CO2 degassing rate at mid-ocean ridges varies by as much as a factor of 3 over the past 200 Myr. We show that mid-ocean ridge melt production and degassing rate would be much larger in the Cretaceous, and reached maximum values at ˜150-120 Ma. Our results raise the possibility that warmer climate in the Cretaceous could be due in part to high magmatic productivity and correspondingly high outgassing rates at mid-ocean ridges during that time.

  10. Diverse patterns of ocean export productivity change across the Cretaceous-Paleogene boundary: New insights from biogenic barium

    NASA Astrophysics Data System (ADS)

    Hull, Pincelli M.; Norris, Richard D.

    2011-09-01

    One of the best-studied aspects of the K-Pg mass extinction is the decline and subsequent recovery of open ocean export productivity (e.g., the flux of organic matter from the surface to deep ocean). Some export proxies, including surface-to-deep water δ13C gradients and carbonate sedimentation rates, indicate a global decline in export productivity triggered by the extinction. In contrast, benthic foraminiferal and other geochemical productivity proxies suggest spatially and temporally heterogeneous K-Pg boundary effects. Here we address these conflicting export productivity patterns using new and compiled measurements of biogenic barium. Unlike a previous synthesis, we find that the boundary effect on export productivity and the timing of recovery varied considerably between different oceanic sites. The northeast and southwest Atlantic, Southern Ocean, and Indian Ocean records saw export production plummet and remain depressed for 350 thousand to 2 million years. Biogenic barium and other proxies in the central Pacific and some upwelling or neritic Atlantic sites indicate the opposite, with proxies recording either no change or increased export production in the early Paleocene. Our results suggest that widespread declines in surface-to-deep ocean δ13C do not record a global decrease in export productivity. Rather, independent proxies, including barium and other geochemical proxies, and benthic community structure, indicate that some regions were characterized by maintained or rapidly recovered organic flux from the surface ocean to the deep seafloor, while other regions had profound reductions in export productivity that persisted long into the Paleocene.

  11. Insect-transmitted viruses affecting tomato production in western North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect-transmitted viruses cause significant losses annually for tomato production in western North America (California and western Mexico). Considerable variability exists among viruses impacting production throughout the region. This is influenced by variable climatic conditions which affect vec...

  12. Controls on 231Pa/230Th in the Indian Ocean: Circulation or Productivity?

    NASA Astrophysics Data System (ADS)

    Thomas, A. L.; Henderson, G. M.; McCave, N.

    2004-12-01

    (231Paxs/230Thxs)0 ratios in marine sediments are a potential proxy of palaeoproductivity and/or past ocean circulation. Studies in the Atlantic have demonstrated the particular potential of this proxy to assess the rate of past circulation AƒAøAøâ_sA¬Aøâ,¬Å" an important environmental variable which is otherwise difficult to reconstruct {[1, 2]}. In this study, we present new water-column and sediment data from the western Indian Ocean to improve understanding of the controls on (231Paxs/230Thxs)0 and test the use of this proxy. The Indian Ocean differs from the Atlantic because deep waters forming in the Southern Ocean and transported into the basin have high rather than low Pa and Th concentrations [3]. The ability to reconstruct past rates of flow into the Indian Ocean would be a powerful new use of Pa/Th, but no data presently exist to test this application. Water samples (10 litre), surface sediments, and a 5.5m Kasten core were collected on the Charles Darwin cruise CD154 from the area East of Madagascar. The down-core record, from10°S extends to 150 ka, and is coupled with a stable isotope stratigraphy and a sortable silt record. Water and sediment samples were analysed for isotopes of Pa, Th and U on a Nu Instruments MC-ICP-MS. The water-column dataset (26 samples) indicate that Pa concentrations are high in NADW transported into the Indian Ocean from the Atlantic, while opal scavenging has lowered Pa concentrations in deeper water masses. Sedimentary 230Th data indicate that there has been significant sediment focusing and that sediment mass fluxes are low. Preliminary sedimentary Pa/Th data show little relation to the sortable silt record. Ongoing Pa/Th and Ba data will complete this downcore record and allow comparison of a Pa/Th record with independent proxies of current speed and productivity in the same core. [1] E.F. Yu, et al, Nature 379, 689-694, 1996. [2] J.F. McManus, et al, Nature 428, 834-837, 2004. [3] M. M. Rutgers van der Loeff

  13. Seasonal cycle of plankton production in the Iberian margin based on a high resolution ocean model

    NASA Astrophysics Data System (ADS)

    Reboreda, Rosa; Nolasco, Rita; Castro, Carmen G.; Álvarez-Salgado, Xosé A.; Cordeiro, Nuno G. F.; Queiroga, Henrique; Dubert, Jesus

    2014-11-01

    The seasonal variability of plankton in the entire Iberian margin and the adjacent oceanic region was simulated by applying a NPZD-type biogeochemical model coupled to a physical high resolution configuration of the 3D Regional Ocean Modeling System (ROMS). The NPZD model simulated the time and space evolution of nitrate, phytoplankton/chlorophyll, zooplankton and detritus. Model results were compared to remotely sensed sea surface temperature from AVHRR, mixed layer depth from ARGO floats, and sea surface chlorophyll-a from a monthly SeaWiFS climatology. The model was able to reasonably reproduce the seasonal cycle of phytoplankton biomass in the Iberian Atlantic margin and the adjacent oceanic region. It allowed us to make a general characterization of the spatio-temporal patterns of phytoplankton and zooplankton biomass, as well as detritus and nitrate distribution. However, some limitations in the model were revealed by the Taylor Diagrams analysis. The model seemed to overestimate the offshore spring phytoplankton bloom and the upwelling-related coastal maxima of chlorophyll-a in the shelf. On the other hand, winter chlorophyll-a decrease simulated by the model over the shelf agreed with in situ samplings reported in the literature, contrasting with the high chlorophyll-a estimations of satellite data. This evidenced that care should be taken when validating model results in the Iberian coastal region using satellite chlorophyll-a products, particularly in winter.

  14. Net community production in the North Atlantic Ocean derived from Volunteer Observing Ship data

    NASA Astrophysics Data System (ADS)

    Ostle, Clare; Johnson, Martin; Landschützer, Peter; Schuster, Ute; Hartman, Susan; Hull, Tom; Robinson, Carol

    2015-01-01

    The magnitude of marine plankton net community production (NCP) is indicative of both the biologically driven exchange of carbon dioxide between the atmosphere and the surface ocean and the export of organic carbon from the surface ocean to the ocean interior. In this study the seasonal variability in the NCP of five biogeochemical regions in the North Atlantic was determined from measurements of surface water dissolved oxygen and dissolved inorganic carbon (DIC) sampled from a Volunteer Observing Ship (VOS). The magnitude of NCP derived from dissolved oxygen measurements (NCPO2) was consistent with previous geochemical estimates of NCP in the North Atlantic, with an average annual NCPO2 of 9.5 ± 6.5 mmol O2 m-2 d-1. Annual NCPO2 did not vary significantly over 35° of latitude and was not significantly different from NCP derived from DIC measurements (NCPDIC). The relatively simple method described here is applicable to any VOS route on which surface water dissolved oxygen concentrations can be accurately measured, thus providing estimates of NCP at higher spatial and temporal resolution than currently achieved.

  15. Sensitivity of Simulated Global Ocean Carbon Flux Estimates to Forcing by Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Casey, Nancy W.; Rousseaux, Cecile S.

    2015-01-01

    Reanalysis products from MERRA, NCEP2, NCEP1, and ECMWF were used to force an established ocean biogeochemical model to estimate air-sea carbon fluxes (FCO2) and partial pressure of carbon dioxide (pCO2) in the global oceans. Global air-sea carbon fluxes and pCO2 were relatively insensitive to the choice of forcing reanalysis. All global FCO2 estimates from the model forced by the four different reanalyses were within 20% of in situ estimates (MERRA and NCEP1 were within 7%), and all models exhibited statistically significant positive correlations with in situ estimates across the 12 major oceanographic basins. Global pCO2 estimates were within 1% of in situ estimates with ECMWF being the outlier at 0.6%. Basin correlations were similar to FCO2. There were, however, substantial departures among basin estimates from the different reanalysis forcings. The high latitudes and tropics had the largest ranges in estimated fluxes among the reanalyses. Regional pCO2 differences among the reanalysis forcings were muted relative to the FCO2 results. No individual reanalysis was uniformly better or worse in the major oceanographic basins. The results provide information on the characterization of uncertainty in ocean carbon models due to choice of reanalysis forcing.

  16. Atmospheric deposition—Another source of nutrients enhancing primary productivity in the eastern tropical Indian Ocean during positive Indian Ocean Dipole phases

    NASA Astrophysics Data System (ADS)

    Siswanto, Eko

    2015-07-01

    This study used in situ and multisensor satellite data and combinations of various primary productivity (PP) and surface nitrate models to assess the contributions of upwelling and atmospheric deposition to modulating PP in the eastern tropical Indian Ocean (ETIO) during positive phases of the Indian Ocean Dipole (+IOD). Surprisingly, atmospheric deposition of nutrients from wildfires accounted for a higher portion of enhanced PP during +IODs than wind-driven nutrient upwelling. Substantial atmospheric nutrient deposition likely also maintains high PP postupwelling and postwildfire. Multiple regression analysis further supported the importance of atmospheric deposition in determining ETIO PP with a significantly large partial regression coefficient for aerosol optical thickness. It is possible that aerosols from major wildfire areas worldwide contribute nutrients that also nontrivially modulate PP in the oceans' main upwelling systems.

  17. The 2004 Indian Ocean Tsunami in Maldives: waves and disaster affected by shape of coral reefs and islands

    NASA Astrophysics Data System (ADS)

    Kan, H.; Ali, M.; Riyaz, M.

    2005-12-01

    In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third of the Maldivian people are severely affected by the Indian Ocean Tsunami in 26 December 2004. We surveyed tsunami impact in 43 islands by measuring island topography and run-up height, interview to local people and mapping of the flooded and destructed areas. The differences in tsunami height and disaster corresponding to the atoll shape and island topography are observed. In the northern atolls, atoll rims consist of many ring-shaped reefs, i.e. miniature atolls called `faro', and interrupted many channels between them. The interrupted atoll rim may play an important role to reducing tsunami run-up height. Severe damage was not observed in the eastern coast of the islands. Beach ridge also contribute to the protection against tsunami. However, in some islands, houses beside the lagoon are damaged by backwashing floodwater from the lagoon. Water marks show the run-up height of -1.8m above MSL. The lagoon water-level seems to set-up by tsunami which permeates into the lagoon through the interrupted atoll rim. The disaster was severe at the southern atolls of Meemu, Thaa and Laamu. The higher run-up heights of up to 3.2m above MSL and enormous building damages were observed at the islands on the eastern atoll rims. The continuous atoll rim of these atolls may reinforce tsunami impact at the eastern islands. In addition, tsunami surge washed the islands totally because of low island topography without beach ridge. Significant floodwater from lagoon was not observed in these atolls. It seems the lagoon water-level was not set-up largely. The continuous atoll rim reduces the tsunami influence to the lagoon and the western side of the atolls. The continuity of atoll rim is probably the major factor to cause the difference in water movement, i.e. tsunami run-up and lagoon set-up, which affects the disaster in the islands. Beach ridge contribute to reduce the tsunami impact to

  18. Marine biological production from in situ oxygen measurements on a profiling float in the subarctic Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Bushinsky, Seth M.; Emerson, Steven

    2015-12-01

    Evaluating the organic carbon flux from the surface ocean to the interior (the marine biological pump) is essential for predictions of ocean carbon cycle feedback to climate change. One approach for determining these fluxes is to measure the concentration of oxygen in the upper ocean over a seasonal cycle, calculate the net O2 flux using an upper ocean model, and then use a stoichiometric relationship between oxygen evolved and organic carbon produced. Applying this tracer in a variety of ocean areas over seasonal cycles requires accurate O2 measurements on autonomous vehicles. Here we demonstrate this approach using an O2 sensor on a profiling float that is periodically calibrated against atmospheric pO2. Using accurate data and a model that includes all physical and biological processes influencing oxygen, we determine an annual net community production of 0.7 ± 0.5 mol C m-2 yr-1 in the northeast Pacific Ocean (50°N, 145°W) from June 2012 to June 2013. There is a strong seasonal cycle in net biological oxygen production with wintertime fluxes caused by bubble processes critical to determining the annual flux. Approximately 50% of net autotrophic production during summer months is consumed by net respiration during the winter. The result is a biological pump in the subarctic Pacific Ocean that is less than that determined by similar methods in the subtropics to the south. This estimate is significantly lower than that predicted by satellite remote sensing and global circulation models.

  19. The presence of the glycolysis operon in SAR11 genomes is positively correlated with ocean productivity.

    PubMed

    Schwalbach, M S; Tripp, H J; Steindler, L; Smith, D P; Giovannoni, S J

    2010-02-01

    Bacteria in the SAR11 clade are highly abundant in marine surface waters, but currently little is known about the carbon compounds that support these large heterotrophic populations. To better understand the carbon requirements of these organisms, we conducted a multiphasic exploration of carbohydrate utilization among SAR11 isolates from the Northeast Pacific Ocean and the Sargasso Sea. A comparison of three SAR11 genomes showed they all lacked a recognizable PTS system, the oxidative portion of the pentose phosphate shunt (zwf-, pgl-), genes for the Embden-Meyerhoff-Parnas (pfk-, pyk-) and Entner-Doudoroff (eda-) pathways of glycolysis. Strain HTCC7211, isolated from an ocean gyre, was missing other glycolysis genes as well. Growth assays, radioisotopes, metagenomics and microarrays were used to test the hypothesis that these isolates might be limited in their abilities to transport and oxidize exogenous carbohydrates. Galactose, fucose, rhamnose, arabinose, ribose and mannose could not serve as carbon sources for the isolates tested. However, differences in glucose utilization were detected between coastal and ocean gyre isolates, with the coastal isolates capable of transporting, incorporating and oxidizing glucose while the open ocean isolate could not. Subsequent microarray analysis of a coastal isolate suggested that an operon encoding a variant of the Entner-Doudoroff pathway is likely responsible for the observed differences in glucose utilization. Metagenomic analysis indicated this operon is more commonly found in coastal environments and is positively correlated with chlorophyll a concentrations. Our results indicated that glycolysis is a variable metabolic property of SAR11 metabolism and suggest that glycolytic SAR11 are more common in productive marine environments.

  20. SeaWiFS ocean color products and services at the NASA Goddard Distributed Active Archive Center (DAAC)

    NASA Astrophysics Data System (ADS)

    Farr, Rebecca A.; Kartan, Ravi; Li, Angela W.; Simmon, Robert B.

    1997-02-01

    SeaWiFS ocean color data will be archived at the Goddard DAAC in early 1997. The Goddard DAAC has been designated the primary archive for all SeaWiFS data. Almost all authorized SeaWiFS users will access SeaWiFS data via the Goddard DAAC Ocean Color Data and Resources web page. New interfaces and services are being developed by the Goddard DAAC Ocean Color Data Support Team on the Ocean Color website to support the SeaWiFS community following launch: A new SeaWiFS WWW Browser will allow users to browse and order SeaWiFS data via the Web. This Browser will incorporate all necessary elements for SeaWiFS data ordering, including password controls, subsetting, coincident search and visual browse. Users will also find SeaWiFS ancillary data, software routines, SeaWiFS data products specification, an order form for the SeaWIFS Technical Memoranda, as well as direct links to the 'Dear Colleague' letter and other documents and software on the SeaWiFS Project homepage. Other ocean color products available at he Goddard DAAC Ocean Color website include the following: New HDF versions of CZCS data files, including browse images and collection of regridded global composites designed for interdisciplinary study. New CZCS read and visualization software are available. A bibliography of ocean color research papers, several previously rare hardcopy documents, and a periodic ocean color newsletter are also available via the Web. The website also contains a collection of several new educational resources for ocean color educators and students. Being the main source of SeaWiFS data and consolidating ocean color data, documents, software, and points of contact form several other sources all at one convenient location, the Goddard DAAC hopes to become an important nexus for the entire global ocean color community. The Ocean Color Data and Resources webpage can be found at http://daac.gsfc.nasa.gov under 'ocean color'. Contact the Goddard DAAC Ocean Color Data Support Team about

  1. Influence of Southern Ocean Intermediate Water on productivity in the eastern equatorial Pacific on orbital timescale

    NASA Astrophysics Data System (ADS)

    Rippert, N.; Max, L.; Tiedemann, R.; Cacho Lascorz, I.; Mackensen, A.

    2015-12-01

    The eastern equatorial Pacific (EEP) is one of the key areas for studying oceanic processes that control atmospheric CO2 concentrations. Southern-sourced water masses (SOIW) are thought to stimulate the biological pump in the EEP and hence contributed to the CO2 drawdown during glacial times. Orbital forcing in combination with local feedback mechanisms are assumed to be the main driver for this water mass advection. Newest studies, however, question the capability of SOIW to stimulate primary productivity during Marine Isotope Stage 2 (MIS2), as nutrients are rather utilized in the Southern Ocean. Instead, nutrient-rich Glacial North Pacific Intermediate Waters (GNPIW) seem to be a major component of water masses upwelled in the EEP to enhance productivity in the EEP during MIS2. We present changes in biological productivity in the EEP over the last 190 ka derived from surface-dwelling planktic foraminifera Globigerinoides ruber and deep-dwelling planktic foraminifera Globorotaloides hexagonus (ODP Site 1240). The δ13C gradient between surface and sub-thermocline (Δδ13Crub-hex) has been used to assess export production in that area. We compare this with variations in the nutrient gradient (Δδ13Chex-SOIW) between sub-thermocline equatorial waters (~350 m) and SOIW. The Δδ13Chex-SOIW variability is dominated by 100 kyr and 23 kyr cycles. This implies a strong response to changes in orbital precession and internal climate forcing related to major changes in ice volume. At times of low precession the difference between the nutrient concentrations of EEP waters and nutrients delivered via SOIW differ substantially, thus indicating that SOIW is not providing sufficient nutrients to stimulate productivity in the EEP. This scenario is most prominent during MIS2 and MIS6. Following the interpretation by Max et al. (submitted) we speculate that similar to MIS2, nutrients were trapped in the Southern Ocean also during MIS6 leaving northward-advected SOIW rather

  2. Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Walter, S.; Kock, A.; Steinhoff, T.; Fiedler, B.; Fietzek, P.; Kaiser, J.; Krol, M. C.; Popa, M. E.; Chen, Q.; Tanhua, T.; Röckmann, T.

    2015-10-01

    Oceans are a net source of molecular hydrogen (H2) to the atmosphere. The production of marine H2 is assumed to be mainly biological by N2 fixation, but photochemical pathways are also discussed. We present measurements of mole fraction and isotopic composition of dissolved and atmospheric H2 from the southern and northern Atlantic between 2008 and 2010. In total almost 400 samples were taken during five cruises along a transect between Punta Arenas (Chile) and Bremerhaven (Germany), as well as at the coast of Mauretania. The isotopic source signatures of dissolved H2 extracted from surface water are highly deuterium-depleted and correlate negatively with temperature, showing δD values of (-629 ± 54) ‰ for water temperatures at (27 ± 3) °C and (-249 ± 88) ‰ below (19 ± 1) °C. The results for warmer water masses are consistent with biological production of H2. This is the first time that marine H2 excess has been directly attributed to biological production by isotope measurements. However, the isotope values obtained in the colder water masses indicate that beside possible biological production a significant different source should be considered. The atmospheric measurements show distinct differences between both hemispheres as well as between seasons. Results from the global chemistry transport model TM5 reproduce the measured H2 mole fractions and isotopic composition well. The climatological global oceanic emissions from the GEMS database are in line with our data and previously published flux calculations. The good agreement between measurements and model results demonstrates that both the magnitude and the isotopic signature of the main components of the marine H2 cycle are in general adequately represented in current atmospheric models despite a proposed source different from biological production or a substantial underestimation of nitrogen fixation by several authors.

  3. Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Walter, S.; Kock, A.; Steinhoff, T.; Fiedler, B.; Fietzek, P.; Kaiser, J.; Krol, M.; Popa, M. E.; Chen, Q.; Tanhua, T.; Röckmann, T.

    2016-01-01

    Oceans are a net source of molecular hydrogen (H2) to the atmosphere. The production of marine H2 is assumed to be mainly biological by N2 fixation, but photochemical pathways are also discussed. We present measurements of mole fraction and isotopic composition of dissolved and atmospheric H2 from the southern and northern Atlantic between 2008 and 2010. In total almost 400 samples were taken during 5 cruises along a transect between Punta Arenas (Chile) and Bremerhaven (Germany), as well as at the coast of Mauritania.

    The isotopic source signatures of dissolved H2 extracted from surface water are highly deuterium-depleted and correlate negatively with temperature, showing δD values of (-629 ± 54) ‰ for water temperatures at (27 ± 3) °C and (-249 ± 88) ‰ below (19 ± 1) °C. The results for warmer water masses are consistent with the biological production of H2. This is the first time that marine H2 excess has been directly attributed to biological production by isotope measurements. However, the isotope values obtained in the colder water masses indicate that beside possible biological production, a significant different source should be considered.

    The atmospheric measurements show distinct differences between both hemispheres as well as between seasons. Results from the global chemistry transport model TM5 reproduce the measured H2 mole fractions and isotopic composition well. The climatological global oceanic emissions from the GEMS database are in line with our data and previously published flux calculations. The good agreement between measurements and model results demonstrates that both the magnitude and the isotopic signature of the main components of the marine H2 cycle are in general adequately represented in current atmospheric models despite a proposed source different from biological production or a substantial underestimation of nitrogen fixation by several authors.

  4. Factors affecting the bioaccessibility of fluoride from seafood products.

    PubMed

    Rocha, R A; de la Fuente, B; Clemente, M J; Ruiz, A; Vélez, D; Devesa, V

    2013-09-01

    Fluoride is considered important for health because of its beneficial effect on the prevention of dental caries and on bone development in the child population. However, excessive intake has negative effects. The main pathway for exposure is oral, through consumption of drinking water, and some food products. Therefore its bioaccessibility (quantity of the element solubilized during the digestive process) is a parameter to be considered when estimating the risk/benefit associated with this element. The aim of the present study was to evaluate the influence of the digestion phase, gastrointestinal digestion factors (pH, pepsin and bile salt concentrations) and the presence of cations on the bioaccessibility of fluoride from seafood products. The results show that the solubilization of fluoride takes place entirely during the gastric phase. Its bioaccessibility is strongly influenced by conditions that favor the formation of insoluble complexes of fluoride with other elements present in the matrix. The factors that are most influential in reducing its bioaccessibility are the increase in pH in the gastric phase, the presence of cations, especially in the intestinal phase, and a low concentration of bile salts.

  5. Gradients in microbial methanol uptake: productive coastal upwelling waters to oligotrophic gyres in the Atlantic Ocean.

    PubMed

    Dixon, Joanna L; Sargeant, Stephanie; Nightingale, Philip D; Colin Murrell, J

    2013-03-01

    Methanol biogeochemistry and its importance as a carbon source in seawater is relatively unexplored. We report the first microbial methanol carbon assimilation rates (k) in productive coastal upwelling waters of up to 0.117±0.002 d(-1) (~10 nmol l(-1 )d(-1)). On average, coastal upwelling waters were 11 times greater than open ocean northern temperate (NT) waters, eight times greater than gyre waters and four times greater than equatorial upwelling (EU) waters; suggesting that all upwelling waters upon reaching the surface (≤20 m), contain a microbial population that uses a relatively high amount of carbon (0.3-10 nmol l(-1 )d(-1)), derived from methanol, to support their growth. In open ocean Atlantic regions, microbial uptake of methanol into biomass was significantly lower, ranging between 0.04-0.68 nmol l(-1 )d(-1). Microbes in the Mauritanian coastal upwelling used up to 57% of the total methanol for assimilation of the carbon into cells, compared with an average of 12% in the EU, and 1% in NT and gyre waters. Several methylotrophic bacterial species were identified from open ocean Atlantic waters using PCR amplification of mxaF encoding methanol dehydrogenase, the key enzyme in bacterial methanol oxidation. These included Methylophaga sp., Burkholderiales sp., Methylococcaceae sp., Ancylobacter aquaticus, Paracoccus denitrificans, Methylophilus methylotrophus, Methylobacterium oryzae, Hyphomicrobium sp. and Methylosulfonomonas methylovora. Statistically significant correlations for upwelling waters between methanol uptake into cells and both chlorophyll a concentrations and methanol oxidation rates suggest that remotely sensed chlorophyll a images, in these productive areas, could be used to derive total methanol biological loss rates, a useful tool for atmospheric and marine climatically active gas modellers, and air-sea exchange scientists.

  6. Hydrographic Processes Driven by Seasonal Monsoon System Affect Siphonophore Assemblages in Tropical-Subtropical Waters (Western North Pacific Ocean)

    PubMed Central

    Lo, Wen-Tseng; Yu, Shwu-Feng; Hsieh, Hung-Yen

    2014-01-01

    This work is a part of the Taiwan Cooperative Oceanic Fisheries Investigation, the first large scale hydrographic and plankton survey around Taiwan (21–26°N, 119–123°E). The present study examined the influence of hydrodynamic and biological variables driven by monsoon system on the siphonophore assemblages through an annual cycle in 2004. Calycophorans, namely Chelophyes appendiculata, Diphyes chamissonis, Lensia subtiloides, Bassia bassensis, and Muggiaea atlantica, were the most dominant siphonophore species. Maximum abundance of these dominant species generally occurred during the warm period (May and August), while M. atlantica had a significantly peak abundance in February. Although no apparently temporal difference in siphonophore abundance was observed in the study, siphonophore assemblage was more diverse in August than in other sampling times. Result of a cluster analysis indicated that assemblage structure of siphonophores in the waters around Taiwan varied at temporal and spatial scales during the sampling period. The intrusions of the Kuroshio Branch Current and China Coastal Current to the study area play an important role on the transportation of siphonophores. Also, the distribution of siphonophore assemblage was closely related to the hydrographic characteristics, with temperature, chlorophyll a concentration, and zooplankton abundance being the major environmental factors affecting the spatio-temporal variability of siphonophores. This study contributes substantially to the new knowledge of the siphonophore assemblage in the tropical-temperate waters of Taiwan. PMID:24932727

  7. 40 CFR 63.5984 - What emission limits must I meet for tire production affected sources?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... tire production affected sources? 63.5984 Section 63.5984 Protection of Environment ENVIRONMENTAL... POLLUTANTS FOR SOURCE CATEGORIES National Emissions Standards for Hazardous Air Pollutants: Rubber Tire Manufacturing Emission Limits for Tire Production Affected Sources § 63.5984 What emission limits must I...

  8. 40 CFR Table 3 to Subpart Nnnnn of... - Performance Test Requirements for HCl Production Affected Sources

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 14 2011-07-01 2011-07-01 false Performance Test Requirements for HCl... Requirements for HCl Production Affected Sources As stated in § 63.9020, you must comply with the following requirements for performance tests for HCl production for each affected source. For each HCl process vent...

  9. Biome-specific scaling of ocean productivity, temperature, and carbon export efficiency

    NASA Astrophysics Data System (ADS)

    Britten, Gregory L.; Primeau, François W.

    2016-05-01

    Mass conservation and metabolic theory place constraints on how marine export production (EP) scales with net primary productivity (NPP) and sea surface temperature (SST); however, little is empirically known about how these relationships vary across ecologically distinct ocean biomes. Here we compiled in situ observations of EP, NPP, and SST and used statistical model selection theory to demonstrate significant biome-specific scaling relationships among these variables. Multiple statistically similar models yield a threefold variation in the globally integrated carbon flux (~4-12 Pg C yr-1) when applied to climatological satellite-derived NPP and SST. Simulated NPP and SST input variables from a 4×CO2 climate model experiment further show that biome-specific scaling alters the predicted response of EP to simulated increases of atmospheric CO2. These results highlight the need to better understand distinct pathways of carbon export across unique ecological biomes and may help guide proposed efforts for in situ observations of the ocean carbon cycle.

  10. Calibration/validation of Landsat-Derived Ocean Colour Products in Boston Harbour

    NASA Astrophysics Data System (ADS)

    Pahlevan, Nima; Sheldon, Patrick; Peri, Francesco; Wei, Jianwei; Shang, Zhehai; Sun, Qingsong; Chen, Robert F.; Lee, Zhongping; Schaaf, Crystal B.; Schott, John R.; Loveland, Thomas

    2016-06-01

    The Landsat data archive provides a unique opportunity to investigate the long-term evolution of coastal ecosystems at fine spatial scales that cannot be resolved by ocean colour (OC) satellite sensors. Recognizing Landsat's limitations in applications over coastal waters, we have launched a series of field campaigns in Boston Harbor and Massachusetts Bay (MA, USA) to validate OC products derived from Landsat-8. We will provide a preliminary demonstration on the calibration/validation of the existing OC algorithms (atmospheric correction and in-water optical properties) to enhance monitoring efforts in Boston Harbor. To do so, Landsat optical images were first compared against ocean colour products over high-latitude regions. The in situ cruise data, including optical data (remote sensing reflectance) and water samples were analyzed to obtain insights into the optical and biogeochemical properties of near-surface waters. Along with the cruise data, three buoys were deployed in three locations across the Harbor to complement our database of concentrations of chlorophyll a, total suspended solids (TSS), and absorption of colour dissolved organic matter (CDOM). The data collected during the first year of the project are used to develop and/or tune OC algorithms. The data will be combined with historic field data to map in-water constituents back to the early 1990's. This paper presents preliminary analysis of some of the data collected under Landsat-8 overpasses.

  11. Ocean Productivity May Predict Recruitment of the Rainbow Wrasse (Coris julis)

    PubMed Central

    Semmens, Brice; Caselle, Jennifer E.; Santos, Ricardo S.; Prakya, Shree R.

    2016-01-01

    Predicting recruitment fluctuations of fish populations remains the Holy Grail of fisheries science. While previous work has linked recruitment of reef fish to environmental variables including temperature, the demonstration of a robust relationship with productivity remains elusive. Despite decades of research, empirical evidence to support this critical link remains limited. Here we identify a consistent and strong relationship between recruitment of a temperate wrasse Coris julis, from temperate reefs in the mid-Atlantic region, with Chlorophyll, over contrasting scales, across multiple years. Additionally, we find that the correlation between Chlorophyll and recruitment is not simply masking a temperature-recruitment relationship. Understanding the potential mechanisms underlying recruitment variability, particularly as it relates to changing climate and ocean regimes, is a critical first step towards characterizing species’ vulnerability to mismatches between pulsed planktonic production and early pelagic life stages. PMID:27824889

  12. Biological production models as elements of coupled, atmosphere-ocean models for climate research

    NASA Technical Reports Server (NTRS)

    Platt, Trevor; Sathyendranath, Shubha

    1991-01-01

    Process models of phytoplankton production are discussed with respect to their suitability for incorporation into global-scale numerical ocean circulation models. Exact solutions are given for integrals over the mixed layer and the day of analytic, wavelength-independent models of primary production. Within this class of model, the bias incurred by using a triangular approximation (rather than a sinusoidal one) to the variation of surface irradiance through the day is computed. Efficient computation algorithms are given for the nonspectral models. More exact calculations require a spectrally sensitive treatment. Such models exist but must be integrated numerically over depth and time. For these integrations, resolution in wavelength, depth, and time are considered and recommendations made for efficient computation. The extrapolation of the one-(spatial)-dimension treatment to large horizontal scale is discussed.

  13. Seabird diversity hotspot linked to ocean productivity in the Canary Current Large Marine Ecosystem

    PubMed Central

    Attrill, Martin J.; Becker, Peter H.; Egevang, Carsten; Furness, Robert W.; Grémillet, David; Kopp, Matthias; Lescroël, Amélie; Matthiopoulos, Jason; Peter, Hans-Ulrich; Phillips, Richard A.

    2016-01-01

    Upwelling regions are highly productive habitats targeted by wide-ranging marine predators and industrial fisheries. In this study, we track the migratory movements of eight seabird species from across the Atlantic; quantify overlap with the Canary Current Large Marine Ecosystem (CCLME) and determine the habitat characteristics that drive this association. Our results indicate the CCLME is a biodiversity hotspot for migratory seabirds; all tracked species and more than 70% of individuals used this upwelling region. Relative species richness peaked in areas where sea surface temperature averaged between 15 and 20°C, and correlated positively with chlorophyll a, revealing the optimum conditions driving bottom-up trophic effects for seabirds. Marine vertebrates are not confined by international boundaries, making conservation challenging. However, by linking diversity to ocean productivity, our research reveals the significance of the CCLME for seabird populations from across the Atlantic, making it a priority for conservation action. PMID:27531154

  14. Seabird diversity hotspot linked to ocean productivity in the Canary Current Large Marine Ecosystem.

    PubMed

    Grecian, W James; Witt, Matthew J; Attrill, Martin J; Bearhop, Stuart; Becker, Peter H; Egevang, Carsten; Furness, Robert W; Godley, Brendan J; González-Solís, Jacob; Grémillet, David; Kopp, Matthias; Lescroël, Amélie; Matthiopoulos, Jason; Patrick, Samantha C; Peter, Hans-Ulrich; Phillips, Richard A; Stenhouse, Iain J; Votier, Stephen C

    2016-08-01

    Upwelling regions are highly productive habitats targeted by wide-ranging marine predators and industrial fisheries. In this study, we track the migratory movements of eight seabird species from across the Atlantic; quantify overlap with the Canary Current Large Marine Ecosystem (CCLME) and determine the habitat characteristics that drive this association. Our results indicate the CCLME is a biodiversity hotspot for migratory seabirds; all tracked species and more than 70% of individuals used this upwelling region. Relative species richness peaked in areas where sea surface temperature averaged between 15 and 20°C, and correlated positively with chlorophyll a, revealing the optimum conditions driving bottom-up trophic effects for seabirds. Marine vertebrates are not confined by international boundaries, making conservation challenging. However, by linking diversity to ocean productivity, our research reveals the significance of the CCLME for seabird populations from across the Atlantic, making it a priority for conservation action.

  15. Drivers of trophic amplification of ocean productivity trends in a changing climate

    NASA Astrophysics Data System (ADS)

    Stock, C. A.; Dunne, J. P.; John, J. G.

    2014-07-01

    Pronounced projected 21st century trends in regional oceanic net primary production (NPP) raise the prospect of significant redistributions of marine resources. Recent results further suggest that NPP changes may be amplified at higher trophic levels. Here, we elucidate the role of planktonic food web dynamics in driving projected changes in mesozooplankton production (MESOZP) found to be, on average, twice as large as projected changes in NPP by the latter half of the 21st century under a high emissions scenario. Globally, MESOZP was projected to decline by 7.9% but regional MESOZP changes sometimes exceeded 50%. Changes in three planktonic food web properties - zooplankton growth efficiency (ZGE), the trophic level of mesozooplankton (MESOTL), and the fraction of NPP consumed by zooplankton (zooplankton-phytoplankton coupling, ZPC), were demonstrated to be responsible for the projected amplification. Zooplankton growth efficiencies (ZGE) changed with NPP, amplifying both NPP increases and decreases. Negative amplification (i.e., exacerbation) of projected subtropical NPP declines via this mechanism was particularly strong since consumers in the subtropics already have limited surplus energy above basal metabolic costs. Increased mesozooplankton trophic level (MESOTL) resulted from projected declines in large phytoplankton production, the primary target of herbivorous mesozooplankton. This further amplified negative subtropical NPP declines but was secondary to ZGE and, at higher latitudes, was often offset by increased ZPC. Marked ZPC increases were projected for high latitude regions experiencing shoaling of deep winter mixing or decreased winter sea ice - both tending to increase winter zooplankton biomass and enhance grazer control of spring blooms. Increased ZPC amplified projected NPP increases associated with declining sea ice in the Artic and damped projected NPP declines associated with decreased mixing in the Northwest Atlantic and Southern Ocean

  16. Sequences affecting the regulation of solvent production in Clostridium acetobutylicum.

    PubMed

    Scotcher, Miles C; Huang, Ke-xue; Harrison, Mary L; Rudolph, Frederick B; Bennett, George N

    2003-07-01

    The high solvent phenotype of Clostridium acetobutylicum mutants B and H was complemented by the introduction of a plasmid that contains either an intact or partially-deleted copy of solR, restoring acetone and butanol production to wild-type levels. This demonstrates that the solR open reading frame on pSOLThi is not required to restore solvent levels. The promoter region upstream of alcohol dehydrogense E (adhE) was examined in efforts to identify sites that play major roles in the control of expression. A series of adhE promoter fragments was constructed and the expression of each in acid- and solvent-phases of growth was analyzed using a chloramphenicol acetyl-transferase reporter system. Our results show that a region beyond the 0A box is needed for full induction of the promoter. Additionally, we show that the presence of sequences around a possible processing site designated S2 may have a negative role in the regulation of adhE expression.

  17. Clinorotation affects morphology and ethylene production in soybean seedlings

    NASA Technical Reports Server (NTRS)

    Hilaire, E.; Peterson, B. V.; Guikema, J. A.; Brown, C. S.; Sager, J. C. (Principal Investigator)

    1996-01-01

    The microgravity environment of spaceflight influences growth, morphology and metabolism in etiolated germinating soybean. To determine if clinorotation will similarly impact these processes, we conducted ground-based studies in conjunction with two space experiment opportunities. Soybean (Glycine max [L.] Merr.) seeds were planted within BRIC (Biological Research In Canister) canisters and grown for seven days at 20 degrees C under clinorotation (1 rpm) conditions or in a stationary upright mode. Gas samples were taken daily and plants were harvested after seven days for measurement of growth and morphology. Compared to the stationary upright controls, plants exposed to clinorotation exhibited increased root length (125% greater) and fresh weight (42% greater), whereas shoot length and fresh weight decreased by 33% and 16% respectively. Plants grown under clinorotation produced twice as much ethylene as the stationary controls. Seedlings treated with triiodo benzoic acid (TIBA), an auxin transport inhibitor, under clinorotation produced 50% less ethylene than the untreated control subjected to the same gravity treatment, whereas a treatment with 2,4-D increased ethylene by five-fold in the clinorotated plants. These data suggest that slow clinorotation influences biomass partitioning and ethylene production in etiolated soybean plants.

  18. Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Fichot, C. G.; Benner, R.

    2012-07-01

    Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the Western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001) in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the Western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the Central Arctic basins.

  19. Synthesis of integrated primary production in the Arctic Ocean: II. In situ and remotely sensed estimates

    NASA Astrophysics Data System (ADS)

    Hill, Victoria J.; Matrai, Patricia A.; Olson, Elise; Suttles, S.; Steele, Mike; Codispoti, L. A.; Zimmerman, Richard C.

    2013-03-01

    Recent warming of surface waters, accompanied by reduced ice thickness and extent may have significant consequences for climate-driven changes of primary production (PP) in the Arctic Ocean (AO). However, it has been difficult to obtain a robust benchmark estimate of pan-Arctic PP necessary for evaluating change. This paper provides an estimate of pan-Arctic PP prior to significant warming from a synthetic analysis of the ARCSS-PP database of in situ measurements collected from 1954 to 2007 and estimates derived from satellite-based observations from 1998 to 2007. Vertical profiles of in situ chlorophyll a (Chl a) and PP revealed persistent subsurface peaks in biomass and PP throughout the AO during most of the summer period. This was contradictory with the commonly assumed exponential decrease in PP with depth on which prior satellite-derived estimates were based. As remotely sensed Chl a was not a good predictor of integrated water column Chl a, accurate satellite-based modeling of vertically integrated primary production (IPPsat), requires knowledge of the subsurface distribution of phytoplankton, coincident with the remotely sensed ocean color measurements. We developed an alternative approach to modeling PP from satellite observations by incorporating climatological information on the depths of the euphotic zone and the mixed layer that control the distribution of phytoplankton that significantly improved the fidelity of satellite derived PP to in situ observations. The annual IPP of the Arctic Ocean combining both in situ and satellite based estimates was calculated here to be a minimum of 466 ± 94 Tg C yr-1 and a maximum of 993 ± 94 Tg C yr-1, when corrected for subsurface production. Inflow shelf seas account for 75% of annual IPP, while the central basin and Beaufort northern sea were the regions with the lowest annual integrated productivity, due to persistently stratified, oligotrophic and ice-covered conditions. Although the expansion of summertime

  20. The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves.

    PubMed

    Zhang, Jinlun; Ashjian, Carin; Campbell, Robert; Hill, Victoria; Spitz, Yvette H; Steele, Michael

    2014-01-01

    [1] 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 phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing

  1. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain sustained observatory

    NASA Astrophysics Data System (ADS)

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; Omar, A. M.; Jeansson, E.; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-10-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the Northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m-2 day-1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production. Seasonal NCP and new production were found to be 4.57 ± 0.85 mol C m-2 and 0.37 ± 0.14 mol N m-2, respectively. The C : N ratio was high (12) compared to the Redfield ratio (6.6), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4 %, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.

  2. 21st century projections of ocean ecology and productivity across the CMIP5 models: contrasting the Southern Ocean and the Arctic

    NASA Astrophysics Data System (ADS)

    Marinov, I.; Cabre, A.; Leung, S.

    2014-12-01

    We use the newest generation of fully-coupled earth system models to study and contrast the response of Southern Ocean and Arctic phytoplankton productivity and biomass to 21st century climate change. The Arctic is warming at a rate much higher than the Southern high latitudes. Despite fundamental differences between the physical responses to climate in these regions, CMIP5 modes predict small increases in biological production both in the SO and the Arctic, partially compensating for the severe loss of primary production in the rest of the oceans. South of 40ºS, the CMIP5 models predict a complex, zonally-banded pattern of phytoplankton abundance and productivity changes driven by shifts in light and iron availability with future warming, in agreement with patterns and mechanisms emerging from a satellite trend analysis and other recent observational work. Increased SAM plays a major role in these projections, as increased Southern Ocean westerlies act both to increase mixing and phytoplankton light limitation in a band around 50S, and to modify iron supply to the surface in regions where phytoplankton are iron limited. By contrast, phytoplankton are light and nitrate co-limited in the strongly stratified Arctic ocean. Here we find that over 100 years, release of light limitation due to sea ice retreat is counter-balanced by an increase in nitrogen limitation due to increased stratification. While most models predict net increases in Arctic production by the end of the 21st century, the different strengths of nutrient-light co-limitation among models result in different magnitude changes in production across models. We assess the multi-model 100-year trend significance using a novel technique based on bootstrap combined with a weighting scheme based in similarity across models. We find that model uncertainty in ecological and biogeochemical parameters is higher than for the physical parameters. Additionally, the spread in model predictions is smaller than the

  3. The value of Operational Ocean SST and Current products in glider deployments

    NASA Astrophysics Data System (ADS)

    Griffin, D.; Proctor, R.; Hollings, B.; Pattiaratchi, C.; Suthers, I.

    2009-04-01

    On November 26, 2008 a Slocum Glider was launched with the mission to explore near-shore processes off southern New South Wales, Australia, then return to the coast. This study contributed to regional activity of the Integrated Marine Observing System (www.imos.org.au), an AU100m 5-year project to establish an ocean and regional ocean observing system for Australia. The planned mission got into difficulties due to the strength of the East Australian Current and the glider began to track offshore and away from the region of interest. In order not to lose the glider to the ocean the mission was redefined to circumnavigate a warm-core eddy evident in satellite imagery. CSIRO routinely generates maps of sea surface temperature from satellite AVHRR imagery and geostrophic currents derived from sea surface height anomalies measured by satellite altimetry. By tracking the development of the SST and geostrophic circulation against the glider reported positions the satellite data helped to guide the glider into the eddy and thus continue the study, even though the satellite SST data quality was low during much of the deployment due to heavy cloud cover, and there being only two altimeters presently useful for estimating currents. The glider was successfully retrieved on December 11, 2008 40km off Jervis Bay after travelling 1002.84 km in 15 days, an average of 0.76m/s, or 1.5kt. This was achieved principally by drifting with the current, and using the glider's 0.25m/s horizontal glide velocity to go sideways with respect to the currents, to get into water thought to be going in the desired direction. The glider was saved and 2374 CTD casts produced giving a valuable dataset for understanding warm-core eddy processes, a dataset which would not have been obtained without the use of operational products.

  4. Standing stocks, production, and respiration of phytoplankton and heterotrophic bacteria in the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.; Hill, Victoria; Cottrell, Matthew T.; Gradinger, Rolf; Malmstrom, Rex R.; Parker, Alexander

    2009-08-01

    Standing stocks and production rates for phytoplankton and heterotrophic bacteria were examined during four expeditions in the western Arctic Ocean (Chukchi Sea and Canada Basin) in the spring and summer of 2002 and 2004. Rates of primary production (PP) and bacterial production (BP) were higher in the summer than in spring and in shelf waters than in the basin. Most surprisingly, PP was 3-fold higher in 2004 than in 2002; ice-corrected rates were 1581 and 458 mg C m -2 d -1, respectively, for the entire region. The difference between years was mainly due to low ice coverage in the summer of 2004. The spatial and temporal variation in PP led to comparable variation in BP. Although temperature explained as much variability in BP as did PP or phytoplankton biomass, there was no relationship between temperature and bacterial growth rates above about 0 °C. The average ratio of BP to PP was 0.06 and 0.79 when ice-corrected PP rates were greater than and less than 100 mg C m -2 d -1, respectively; the overall average was 0.34. Bacteria accounted for a highly variable fraction of total respiration, from 3% to over 60% with a mean of 25%. Likewise, the fraction of PP consumed by bacterial respiration, when calculated from growth efficiency (average of 6.9%) and BP estimates, varied greatly over time and space (7% to >500%). The apparent uncoupling between respiration and PP has several implications for carbon export and storage in the western Arctic Ocean.

  5. The inhibition of N2O production by ocean acidification in cold temperate and polar waters

    NASA Astrophysics Data System (ADS)

    Rees, Andrew P.; Brown, Ian J.; Jayakumar, Amal; Ward, Bess B.

    2016-05-01

    The effects of ocean acidification (OA) on nitrous oxide (N2O) production and on the community composition of ammonium oxidizing archaea (AOA) were examined in the northern and southern sub-polar and polar Atlantic Ocean. Two research cruises were performed during June 2012 between the North Sea and Arctic Greenland and Barent Seas, and in January-February 2013 to the Antarctic Scotia Sea. Seven stations were occupied in all during which shipboard experimental manipulations of the carbonate chemistry were performed through additions of NaHCO3-+HCl in order to examine the impact of short-term (48 h for N2O and between 96 and 168 h for AOA) exposure to control and elevated conditions of OA. During each experiment, triplicate incubations were performed at ambient conditions and at 3 lowered levels of pH which varied between 0.06 and 0.4 units according to the total scale and which were targeted at CO2 partial pressures of ~500, 750 and 1000 μatm. The AOA assemblage in both Arctic and Antarctic regions was dominated by two major archetypes that represent the marine AOA clades most often detected in seawater. There were no significant changes in AOA assemblage composition between the beginning and end of the incubation experiments. N2O production was sensitive to decreasing pHT at all stations and decreased by between 2.4% and 44% with reduced pHT values of between 0.06 and 0.4. The reduction in N2O yield from nitrification was directly related to a decrease of between 28% and 67% in available NH3 as a result of the pH driven shift in the NH3:NH4+ equilibrium. The maximum reduction in N2O production at conditions projected for the end of the 21st century was estimated to be 0.82 Tg N y-1.

  6. The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Palevsky, Hilary I.; Quay, Paul D.; Lockwood, Deirdre E.; Nicholson, David P.

    2016-02-01

    We measured triple oxygen isotopes and oxygen/argon dissolved gas ratios as nonincubation-based geochemical tracers of gross oxygen production (GOP) and net community production (NCP) on 16 container ship transects across the North Pacific from 2008 to 2012. We estimate rates and efficiency of biological carbon export throughout the full annual cycle across the North Pacific basin (35°N-50°N, 142°E-125°W) by constructing mixed layer budgets that account for physical and biological influences on these tracers. During the productive season from spring to fall, GOP and NCP are highest in the Kuroshio region west of 170°E and decrease eastward across the basin. However, deep winter mixed layers (>200 m) west of 160°W ventilate ~40-90% of this seasonally exported carbon, while only ~10% of seasonally exported carbon east of 160°W is ventilated in winter where mixed layers are <120 m. As a result, despite higher annual GOP in the west than the east, the annual carbon export (sequestration) rate and efficiency decrease westward across the basin from export of 2.3 ± 0.3 mol C m-2 yr-1 east of 160°W to 0.5 ± 0.7 mol C m-2 yr-1 west of 170°E. Existing productivity rate estimates from time series stations are consistent with our regional productivity rate estimates in the eastern but not western North Pacific. These results highlight the need to estimate productivity rates over broad spatial areas and throughout the full annual cycle including during winter ventilation in order to accurately estimate the rate and efficiency of carbon sequestration via the ocean's biological pump.

  7. Impact of icebergs on net primary productivity in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Wu, Shuang-Ye; Hou, Shugui

    2017-03-01

    Productivity in the Southern Ocean (SO) is iron-limited, and supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine environment. However, recent studies show that icebergs could provide a comparable amount of bioavailable iron to the SO as aeolian dust. In addition, small-scale areal studies suggest increased concentrations of chlorophyll, krill, and seabirds surrounding icebergs. Based on previous research, this study aims to examine whether iceberg occurrence has a significant impact on marine productivity at the scale of the SO, using remote sensing data of iceberg occurrences and ocean net primary productivity (NPP) covering the period 2002-2014. The impacts of both large and small icebergs are examined in four major ecological zones of the SO: the continental shelf zone (CSZ), the seasonal ice zone (SIZ), the permanent open ocean zone (POOZ), and the polar front zone (PFZ). We found that the presence of icebergs is associated with elevated levels of NPP, but the differences vary in different zones. Grid cells with small icebergs on average have higher NPP than other cells in most iron-deficient zones: 21 % higher for the SIZ, 16 % for the POOZ, and 12 % for the PFZ. The difference is relatively small in the CSZ where iron is supplied from meltwater and sediment input from the continent. In addition, NPP of grid cells adjacent to large icebergs on average is 10 % higher than that of control cells in the vicinity. The difference is larger at higher latitudes, where most large icebergs are concentrated. From 1992 to 2014, there is a significant increasing trend for both small and large icebergs. The increase was most rapid in the early 2000s and has leveled off since then. As the climate continues to warm, the Antarctic Ice Sheet is expected to experience increased mass loss as a whole, which could lead to more icebergs in the region. Based on our study, this could result in a higher level of NPP in the SO as a whole

  8. Climate change decouples oceanic primary and export productivity and organic carbon burial

    PubMed Central

    Lopes, Cristina; Kucera, Michal; Mix, Alan C.

    2015-01-01

    Understanding responses of oceanic primary productivity, carbon export, and burial to climate change is essential for model-based projection of biological feedbacks in a high-CO2 world. Here we compare estimates of productivity based on the composition of fossil diatom floras with organic carbon burial off Oregon in the Northeast Pacific across a large climatic transition at the last glacial termination. Although estimated primary productivity was highest during the Last Glacial Maximum, carbon burial was lowest, reflecting reduced preservation linked to low sedimentation rates. A diatom size index further points to a glacial decrease (and deglacial increase) in the fraction of fixed carbon that was exported, inferred to reflect expansion, and contraction, of subpolar ecosystems that today favor smaller plankton. Thus, in contrast to models that link remineralization of carbon to temperature, in the Northeast Pacific, we find dominant ecosystem and sea floor control such that intervals of warming climate had more efficient carbon export and higher carbon burial despite falling primary productivity. PMID:25453073

  9. Climate change decouples oceanic primary and export productivity and organic carbon burial

    NASA Astrophysics Data System (ADS)

    Lopes, Cristina; Kucera, Michal; Mix, Alan C.

    2015-01-01

    Understanding responses of oceanic primary productivity, carbon export, and burial to climate change is essential for model-based projection of biological feedbacks in a high-CO2 world. Here we compare estimates of productivity based on the composition of fossil diatom floras with organic carbon burial off Oregon in the Northeast Pacific across a large climatic transition at the last glacial termination. Although estimated primary productivity was highest during the Last Glacial Maximum, carbon burial was lowest, reflecting reduced preservation linked to low sedimentation rates. A diatom size index further points to a glacial decrease (and deglacial increase) in the fraction of fixed carbon that was exported, inferred to reflect expansion, and contraction, of subpolar ecosystems that today favor smaller plankton. Thus, in contrast to models that link remineralization of carbon to temperature, in the Northeast Pacific, we find dominant ecosystem and sea floor control such that intervals of warming climate had more efficient carbon export and higher carbon burial despite falling primary productivity.

  10. Climate change decouples oceanic primary and export productivity and organic carbon burial.

    PubMed

    Lopes, Cristina; Kucera, Michal; Mix, Alan C

    2015-01-13

    Understanding responses of oceanic primary productivity, carbon export, and burial to climate change is essential for model-based projection of biological feedbacks in a high-CO2 world. Here we compare estimates of productivity based on the composition of fossil diatom floras with organic carbon burial off Oregon in the Northeast Pacific across a large climatic transition at the last glacial termination. Although estimated primary productivity was highest during the Last Glacial Maximum, carbon burial was lowest, reflecting reduced preservation linked to low sedimentation rates. A diatom size index further points to a glacial decrease (and deglacial increase) in the fraction of fixed carbon that was exported, inferred to reflect expansion, and contraction, of subpolar ecosystems that today favor smaller plankton. Thus, in contrast to models that link remineralization of carbon to temperature, in the Northeast Pacific, we find dominant ecosystem and sea floor control such that intervals of warming climate had more efficient carbon export and higher carbon burial despite falling primary productivity.

  11. Late summer net community production in the central Arctic Ocean using multiple approaches

    NASA Astrophysics Data System (ADS)

    Ulfsbo, Adam; Cassar, Nicolas; Korhonen, Meri; Heuven, Steven; Hoppema, Mario; Kattner, Gerhard; Anderson, Leif G.

    2014-10-01

    Large-scale patterns of net community production (NCP) were estimated during the late summer cruise ARK-XXVI/3 (TransArc, August/September 2011) to the central Arctic Ocean. Several approaches were used based on the following: (i) continuous measurements of surface water oxygen to argon ratios (O2/Ar), (ii) underway measurements of surface partial pressure of carbon dioxide (pCO2), (iii) discrete samples of dissolved inorganic carbon, and (iv) dissolved inorganic nitrogen and phosphate. The NCP estimates agreed well within the uncertainties associated with each approach. The highest late summer NCP (up to 6 mol C m-2) was observed in the marginal sea ice zone region. Low values (<1 mol C m-2) were found in the sea ice-covered deep basins with a strong spatial variability. Lowest values were found in the Amundsen Basin and moderate values in the Nansen and Makarov Basins with slightly higher estimates over the Mendeleev Ridge. Our findings support a coupling of NCP to sea ice coverage and nutrient supply and thus stress a potential change in spatial and temporal distribution of NCP in a future Arctic Ocean. To follow the evolution of NCP in space and time, it is suggested to apply one or several of these approaches in shipboard investigations with a time interval of 3 to 5 years.

  12. Isotopic disequilibrium in Globigerina bulloides and carbon isotope response to productivity increase in Southern Ocean

    PubMed Central

    Prasanna, K.; Ghosh, Prosenjit; Bhattacharya, S. K.; Mohan, K.; Anilkumar, N.

    2016-01-01

    Oxygen and carbon isotope ratios in planktonic foraminifera Globigerina bulloides collected from tow samples along a transect from the equatorial Indian ocean to the Southern Ocean (45°E and 80°E and 10°N to 53°S) were analysed and compared with the equilibrium δ18O and δ13C values of calcite calculated using the temperature and isotopic composition of the water column. The results agree within ~0.25‰ for the region between 10°N and 40°S and 75–200 m water depth which is considered to be the habitat of Globigerina bulloides. Further south (from 40°S to 55°S), however, the measured δ18O and δ13C values are higher than the expected values by ~2‰ and ~1‰ respectively. These enrichments can be attributed to either a ‘vital effect’ or a higher calcification rate. An interesting pattern of increase in the δ13C(DIC) value of the surface water with latitude is observed between 35°S and~ 60°S, with a peak at~ 42°S. This can be caused by increased organic matter production and associated removal. A simple model accounting for the increase in the δ13C(DIC) values is proposed which fits well with the observed chlorophyll abundance as a function of latitude. PMID:26903274

  13. Integration of radiative transfer into satellite models of ocean primary production

    NASA Astrophysics Data System (ADS)

    Smyth, T. J.; Tilstone, G. H.; Groom, S. B.

    2005-10-01

    A major goal of ocean color observations from space is the determination of phytoplankton primary productivity (PP) and hence oceanic carbon uptake. Results of a PP model implemented to use satellite-derived fields of chlorophyll, photosynthetically available radiation (PAR) and sea-surface temperature (SST) are presented. The model gave a global estimate of PP of around 57 Gt C yr-1 and gives a low RMS (0.16) when compared with in situ data. However, as the model's in-water light field parameterization only considers attenuation by pure water and chlorophyll, PP is overestimated in case II waters where other optically important constituents such as colored dissolved organic matter (CDOM) and suspended particulate matter (SPM) are also present. This paper develops a novel technique to determine PP by coupling a radiative transfer code, which allows the inclusion of CDOM and SPM, to the original photosynthesis model. For the global calculations, a look-up table has been generated using chlorophyll, CDOM, SST, PAR and day length as inputs. The resultant 364,500 element look-up table has been applied to data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate-Resolution Imaging Spectroradiometer (MODIS). PP retrievals are improved in case II waters and global estimates are reduced to between 52 and 55 Gt C yr-1.

  14. Isotopic disequilibrium in Globigerina bulloides and carbon isotope response to productivity increase in Southern Ocean.

    PubMed

    Prasanna, K; Ghosh, Prosenjit; Bhattacharya, S K; Mohan, K; Anilkumar, N

    2016-02-23

    Oxygen and carbon isotope ratios in planktonic foraminifera Globigerina bulloides collected from tow samples along a transect from the equatorial Indian ocean to the Southern Ocean (45°E and 80°E and 10°N to 53°S) were analysed and compared with the equilibrium δ(18)O and δ(13)C values of calcite calculated using the temperature and isotopic composition of the water column. The results agree within ~0.25‰ for the region between 10°N and 40°S and 75-200 m water depth which is considered to be the habitat of Globigerina bulloides. Further south (from 40°S to 55°S), however, the measured δ(18)O and δ(13)C values are higher than the expected values by ~2‰ and ~1‰ respectively. These enrichments can be attributed to either a 'vital effect' or a higher calcification rate. An interesting pattern of increase in the δ(13)C(DIC) value of the surface water with latitude is observed between 35°S and~ 60°S, with a peak at~ 42°S. This can be caused by increased organic matter production and associated removal. A simple model accounting for the increase in the δ(13)C(DIC) values is proposed which fits well with the observed chlorophyll abundance as a function of latitude.

  15. Bio-mining the microbial treasures of the ocean: new natural products.

    PubMed

    Imhoff, Johannes F; Labes, Antje; Wiese, Jutta

    2011-01-01

    The biological resources of the oceans have been exploited since ancient human history, mainly by catching fish and harvesting algae. Research on natural products with special emphasis on marine animals and also algae during the last decades of the 20th century has revealed the importance of marine organisms as producers of substances useful for the treatment of human diseases. Though a large number of bioactive substances have been identified, some many years ago, only recently the first drugs from the oceans were approved. Quite astonishingly, the immense diversity of microbes in the marine environments and their almost untouched capacity to produce natural products and therefore the importance of microbes for marine biotechnology was realized on a broad basis by the scientific communities only recently. This has strengthened worldwide research activities dealing with the exploration of marine microorganisms for biotechnological applications, which comprise the production of bioactive compounds for pharmaceutical use, as well as the development of other valuable products, such as enzymes, nutraceuticals and cosmetics. While the focus in these fields was mainly on marine bacteria, also marine fungi now receive growing attention. Although culture-dependent studies continue to provide interesting new chemical structures with biological activities at a high rate and represent highly promising approaches for the search of new drugs, exploration and use of genomic and metagenomic resources are considered to further increase this potential. Many efforts are made for the sustainable exploration of marine microbial resources. Large culture collections specifically of marine bacteria and marine fungi are available. Compound libraries of marine natural products, even of highly purified substances, were established. The expectations into the commercial exploitation of marine microbial resources has given rise to numerous institutions worldwide, basic research facilities as

  16. Shelf and open-ocean calcareous phytoplankton assemblages across the Paleocene-Eocene thermal maximum: Implications for global productivity gradients

    USGS Publications Warehouse

    Gibbs, S.J.; Bralower, T.J.; Bown, P.R.; Zachos, J.C.; Bybell, L.M.

    2006-01-01

    Abrupt global warming and profound perturbation of the carbon cycle during the Paleocene-Eocene Thermal Maximum (PETM, ca. 55 Ma) have been linked to a massive release of carbon into the ocean-atmosphere system. Increased phytoplankton productivity has been invoked to cause subsequent CO2 drawdown, cooling, and environmental recovery. However, interpretations of geochemical and biotic data differ on when and where this increased productivity occurred. Here we present high-resolution nannofossil assemblage data from a shelf section (the U.S. Geological Survey [USGS] drill hole at Wilson Lake, New Jersey) and an open-ocean location (Ocean Drilling Program [ODP] Site 1209, paleoequatorial Pacific). These data combined with published biotic records indicate a transient steepening of shelf-offshelf trophic gradients across the PETM onset and peak, with a decrease in open-ocean productivity coeval with increased nutrient availability in shelf areas. Productivity levels recovered in the open ocean during the later stages of the event, which, coupled with intensified continental weathering rates, may have played an important role in carbon sequestration and CO2 drawdown. ?? 2006 Geological Society of America.

  17. Hidden biosphere in an oxygen-deficient Atlantic open ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Loescher, Carolin; Fischer, Martin; Neulinger, Sven; Fiedler, Björn; Philippi, Miriam; Schütte, Florian; Singh, Arvind; Hauss, Helena; Karstensen, Johannes; Körtzinger, Arne; Schmitz, Ruth

    2016-04-01

    The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of approximately 40 μmol kg-1. The recent discovery of re-occurring mesoscale eddies with close to anoxic O2 concentrations (<1 μmol kg-1) located just below the mixed layer has challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our data indicate that high primary production in the eddy fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed layer base. The O2-depleted core waters eddy promoted transcription of the key gene for denitrification, nirS. This process is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.

  18. Hidden biosphere in an oxygen-deficient Atlantic open ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Löscher, C. R.; Fischer, M. A.; Neulinger, S. C.; Fiedler, B.; Philippi, M.; Schütte, F.; Singh, A.; Hauss, H.; Karstensen, J.; Körtzinger, A.; Künzel, S.; Schmitz, R. A.

    2015-08-01

    The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of around 40 μmol kg-1. Only recently, the discovery of re-occurring mesoscale eddies with sometimes close to anoxic O2 concentrations (<1 μmol kg-1) and located just below the mixed layer challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first metagenomic dataset from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed a significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and increased carbon uptake rates up to three times as high as in surrounding waters. Carbon uptake below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our combined data indicate that high primary production in the eddy fuels export production and the presence of a specific microbial community responsible for enhanced respiration at shallow depths, below the mixed layer base. Progressively decreasing O2 concentrations in the eddy were found to promote transcription of the key gene for denitrification, nirS, in the O2-depleted core waters. This process is usually absent from the open ETNA waters. In the light of future ocean deoxygenation our results show exemplarily that even distinct events of anoxia have the potential to alter microbial community structures and with that critically impact primary productivity and biogeochemical processes of oceanic water bodies.

  19. Estimates of oceanic mesozooplankton production: a comparison using the Bermuda and Hawaii time-series data

    NASA Astrophysics Data System (ADS)

    Roman, M. R.; Adolf, H. A.; Landry, M. R.; Madin, L. P.; Steinberg, D. K.; Zhang, X.

    Mesozooplankton growth rates were estimated for the Hawaiian (HOT) and Bermuda (BATS) ocean time-series stations using the empirical model of Hirst and Lampitt (Marine Biology 132 (1998) 247), which predicts copepod growth rate from temperature and body size. Using this approach we derived seasonal and annual estimates of mesozooplankton production as well as rates of mesozooplankton ingestion and egestion using assumed growth and assimilation efficiencies for the period 1994-1997. Annual mesozooplankton production estimates at HOT (average 0.79 mol C m -2 yr -1) were higher than production estimates at BATS (average 0.33 mol C m -2 yr -1) due to both higher mesozooplankton biomass and higher estimated mesozooplankton individual growth rates. Annual primary production at the two sites was similar (average 14.92 mol C m -2 yr -1 at HOT and 13.43 mol C m -2 yr -1 at BATS). Thus, mesozooplankton production was a greater fraction of primary production at HOT (0.05) as compared to BATS (0.02). Mesozooplankton potentially contributed more to the gravitational flux of carbon at HOT, where the ratio of the average annual estimate of mesozooplankton fecal pellet carbon production/annual estimate of carbon flux at the base of the euphotic zone was 1.03 compared to the same ratio of 0.39 at BATS. Mortality estimates were similar to estimates of mesozooplankton production when compared over the entire study period. The higher mesozooplankton biomass and derived rate parameters at HOT compared to BATS may be due to the more episodic nature of nutrient inputs at BATS, which could result in mis-matches between increases in phytoplankton production and the grazing/production response by mesozooplankton. In addition, there is evidence to suggest that there are periodic blooms of gelatinous macrozooplankton (salps) at BATS that may not be captured sufficiently by the monthly sampling program. Thus the gelatinous zooplankton would add to the overall grazing impact on the

  20. Synergetic impact of Southern Ocean ventilation and -export production on atmospheric CO2 during the last deglacial and glacial periods

    NASA Astrophysics Data System (ADS)

    Skinner, L. C.; Gottschalk, J.; Lippold, J. A.; Vogel, H.; Frank, N.; Jaccard, S.; Waelbroeck, C.

    2015-12-01

    Millennial climate changes during the last deglacial and glacial periods were accompanied by rapid changes in atmospheric CO2 (CO2,atm) that still remain unexplained. While the role of the Southern Ocean as major control of ocean-atmosphere CO2 exchange has often been emphasized, it has been debated whether millennial-scale rises in CO2,atm are linked with variations in biological export productivity in the sub-Antarctic region, possibly driven by fluctuations in airborne dust supply, or with variations in vertical mixing in the Antarctic region, possibly driven by changes in westerly wind stress or density stratification of the water column. We present high-resolution multi-proxy bottom water [O2]- (closely linked to dissolved organic carbon concentrations in the ocean), biological export production- and 14C ventilation age reconstructions in the sub-Antarctic Atlantic sediment core MD07-3076Q (14°13.7'W, 44°9.2'S, 3770 m water depth), to provide new insights into the role of the Southern Ocean in the global carbon cycle from a deep-sea perspective. Our new data show that millennial-scale changes in CO2,atm during the last 70,000 years were paralleled by decreases in deep-ocean carbon storage, which were linked with increases in deep-ocean ventilation of the Southern Ocean carbon pool (via southern-sourced water masses) and decreases in the export of carbon to the deep sub-Antarctic Atlantic. Reconstructed bottom water [O2] changes indicate a deep-ocean carbon loss of 509±68 Gt C during the early deglaciation and 292±111 Gt C during mid-glacial events, when extrapolated to the global deep ocean below 3 km, which may fully account for the observed CO2,atm changes. We propose that the Southern Ocean's 'organic carbon pump' has exerted a tight control on CO2,atm and global climate specifically via a synergy of both physical (e.g. ocean dynamics, and air-sea CO2 exchange) and biological processes (e.g. export productivity).

  1. Nematode community composition and feeding shaped by contrasting productivity regimes in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Lins, Lidia; da Silva, Maria Cristina; Hauquier, Freija; Esteves, André Morgado; Vanreusel, Ann

    2015-05-01

    In the Southern Ocean, during the ANT-XXVIII expedition (RV Polarstern), four stations contrasting in terms of surface primary productivity were studied along the Polar Front from 39°W to 10°E. We investigated to what extent differences in surface primary productivity, together with benthic environmental parameters (concentration of Chlorophyll a and its derivatives, and sediment fatty acid composition) mirrored in nematode standing stocks (i.e. density and biomass) and differences in community composition. Moreover, nematode fatty acid (FA) analyses were performed to unravel feeding selectivity patterns on "bulk" nematodes and particular nematode taxa (Desmodora and Desmoscolecidae). South Georgia station, located NW of South Georgia island, possessed not only highest surface primary productivity, but also highest Chlorophyll a (and its derivatives) and total sediment FA concentrations, also reflected in up to 10-fold higher nematode standing stocks. FA composition from "bulk" nematodes, Desmodora and desmoscolecids revealed a planktonic-based diet, as revealed by diatom biomarkers (16:1 ω 7/16:0 > 1) for "bulk" nematodes and Desmodora from South Georgia. Nematodes at the other stations situated more to the east showed non-selectivity for fresh diatom material based on the FA composition, associated with low surface primary productivity and low labile carbon concentrations (low Chlorophyll a values) in these areas. Uncommonly found in typical deep-sea environments, the nematode genus Desmodora exhibited high numbers at South Georgia station, probably as a response to the high primary productivity at the surface, confirming the strong benthic-pelagic coupling even at great depths. This study suggests that alterations in nematode standing stocks and community composition, together with selective feeding reflected by distinct FA composition, can be positively associated and shaped by surface productivity regimes.

  2. Ecosystem model intercomparison of under-ice and total primary production in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Jin, Meibing; Popova, Ekaterina E.; Zhang, Jinlun; Ji, Rubao; Pendleton, Daniel; Varpe, Øystein; Yool, Andrew; Lee, Younjoo J.

    2016-01-01

    Previous observational studies have found increasing primary production (PP) in response to declining sea ice cover in the Arctic Ocean. In this study, under-ice PP was assessed based on three coupled ice-ocean-ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project. All models showed good agreement with under-ice measurements of surface chlorophyll-a concentration and vertically integrated PP rates during the main under-ice production period, from mid-May to September. Further, modeled 30-year (1980-2009) mean values and spatial patterns of sea ice concentration compared well with remote sensing data. Under-ice PP was higher in the Arctic shelf seas than in the Arctic Basin, but ratios of under-ice PP over total PP were spatially correlated with annual mean sea ice concentration, with higher ratios in higher ice concentration regions. Decreases in sea ice from 1980 to 2009 were correlated significantly with increases in total PP and decreases in the under-ice PP/total PP ratio for most of the Arctic, but nonsignificantly related to under-ice PP, especially in marginal ice zones. Total PP within the Arctic Circle increased at an annual rate of between 3.2 and 8.0 Tg C/yr from 1980 to 2009. This increase in total PP was due mainly to a PP increase in open water, including increases in both open water area and PP rate per unit area, and therefore much stronger than the changes in under-ice PP. All models suggested that, on a pan-Arctic scale, the fraction of under-ice PP declined with declining sea ice cover over the last three decades.

  3. How will ocean acidification affect Baltic sea ecosystems? an assessment of plausible impacts on key functional groups.

    PubMed

    Havenhand, Jonathan N

    2012-09-01

    Increasing partial pressure of atmospheric CO₂ is causing ocean pH to fall-a process known as 'ocean acidification'. Scenario modeling suggests that ocean acidification in the Baltic Sea may cause a ≤ 3 times increase in acidity (reduction of 0.2-0.4 pH units) by the year 2100. The responses of most Baltic Sea organisms to ocean acidification are poorly understood. Available data suggest that most species and ecologically important groups in the Baltic Sea food web (phytoplankton, zooplankton, macrozoobenthos, cod and sprat) will be robust to the expected changes in pH. These conclusions come from (mostly) single-species and single-factor studies. Determining the emergent effects of ocean acidification on the ecosystem from such studies is problematic, yet very few studies have used multiple stressors and/or multiple trophic levels. There is an urgent need for more data from Baltic Sea populations, particularly from environmentally diverse regions and from controlled mesocosm experiments. In the absence of such information it is difficult to envision the likely effects of future ocean acidification on Baltic Sea species and ecosystems.

  4. New production in the warm waters of the tropical Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Pena, M. Angelica; Lewis, Marlon R.; Cullen, John J.

    1994-01-01

    The average depth-integrated rate of new production in the tropical Pacific Ocean was estimated from a calculation of horizontal and vertical nitrate balance over the region enclosed by the climatological 26 C isotherm. The net turbulent flux of nitrate into the region was computed in terms of the climatological net surface heat flux and the nitrate-temperature relationship at the base of the 26 C isotherm. The net advective transport of nitrate into the region was estimated using the mean nitrate distribution obtained from the analysis of historical data and previous results of a general circulation model of the tropical Pacific. The rate of new production resulting from vertical turbulent fluxes of nitrate was found to be similar in magnitude to that due to advective transport. Most (about 75%) of the advective input of nitrate was due to the horizontal transport of nutrient-rich water from the eastern equatorial region rather than from equatorial upwelling. An average rate of new production of 14.5 - 16 g C/sq m/yr was found for the warm waters of the tropical Pacific region. These values are in good agreement with previous estimates for this region and are almost five times less than is estimated for the eastern equatorial Pacific, where most of the nutrient upwelling occurs.

  5. The rise of ocean giants: maximum body size in Cenozoic marine mammals as an indicator for productivity in the Pacific and Atlantic Oceans

    PubMed Central

    Vermeij, Geerat J.

    2016-01-01

    Large consumers have ecological influence disproportionate to their abundance, although this influence in food webs depends directly on productivity. Evolutionary patterns at geologic timescales inform expectations about the relationship between consumers and productivity, but it is very difficult to track productivity through time with direct, quantitative measures. Based on previous work that used the maximum body size of Cenozoic marine invertebrate assemblages as a proxy for benthic productivity, we investigated how the maximum body size of Cenozoic marine mammals, in two feeding guilds, evolved over comparable temporal and geographical scales. First, maximal size in marine herbivores remains mostly stable and occupied by two different groups (desmostylians and sirenians) over separate timeframes in the North Pacific Ocean, while sirenians exclusively dominated this ecological mode in the North Atlantic. Second, mysticete whales, which are the largest Cenozoic consumers in the filter-feeding guild, remained in the same size range until a Mio-Pliocene onset of cetacean gigantism. Both vertebrate guilds achieved very large size only recently, suggesting that different trophic mechanisms promoting gigantism in the oceans have operated in the Cenozoic than in previous eras. PMID:27381883

  6. The rise of ocean giants: maximum body size in Cenozoic marine mammals as an indicator for productivity in the Pacific and Atlantic Oceans.

    PubMed

    Pyenson, Nicholas D; Vermeij, Geerat J

    2016-07-01

    Large consumers have ecological influence disproportionate to their abundance, although this influence in food webs depends directly on productivity. Evolutionary patterns at geologic timescales inform expectations about the relationship between consumers and productivity, but it is very difficult to track productivity through time with direct, quantitative measures. Based on previous work that used the maximum body size of Cenozoic marine invertebrate assemblages as a proxy for benthic productivity, we investigated how the maximum body size of Cenozoic marine mammals, in two feeding guilds, evolved over comparable temporal and geographical scales. First, maximal size in marine herbivores remains mostly stable and occupied by two different groups (desmostylians and sirenians) over separate timeframes in the North Pacific Ocean, while sirenians exclusively dominated this ecological mode in the North Atlantic. Second, mysticete whales, which are the largest Cenozoic consumers in the filter-feeding guild, remained in the same size range until a Mio-Pliocene onset of cetacean gigantism. Both vertebrate guilds achieved very large size only recently, suggesting that different trophic mechanisms promoting gigantism in the oceans have operated in the Cenozoic than in previous eras.

  7. Turnover, Diversity, and Productivity of Siliceous Plankton in the Pliocene Southern Ocean

    NASA Astrophysics Data System (ADS)

    Cody, R. D.; Naish, T.; Crampton, J. S.; Levy, R. H.

    2010-12-01

    The siliceous microfossil record of the Southern Ocean and Antarctic margin reveals much about the climatic and oceanographic evolution of the region during the late Cenozoic. We have constructed a composite record of the first and last appearances of 106 diatom taxa and 96 radiolarian taxa from 40 Neogene drillcores ranging from 40-80°S latitude. The composite biostratigraphic ranges, which correct for incomplete preservation and sampling in individual sections, are dated to within an average of ±33kyrs for the Pliocene, and allow us to discriminate local migration events from regional origination and extinction events. We examine the environmental history of the region in the context of the pace of evolution and extinction, regional diversity and productivity, and the biogeographic ranges of individual species through time. The Miocene-Pliocene transition was marked by a dramatic increase in nearshore biosiliceous production around the Antarctic margin, suggesting a longer growing season and enhanced nutrient supply in the warm Pliocene. The start of the Pliocene was also marked by rapid synchronous evolutionary turnover among both diatoms and radiolaria. However, whereas endemic diatom diversity increased throughout the Pliocene and underwent a subsequent major turnover pulse ~3.5Ma, rates of origination and extinction among radiolaria have been uniformly low since 4.7Ma. Episodes of rapid turnover among diatoms (5.0-4.7Ma, and 3.6-3.3Ma) coincide with intervals of elevated environmental instability, as measured by long-term benthic oxygen isotope variance. They may also reflect profound oceanographic transitions which altered the biogeographic isolation and nutrient supply patterns of the region. High endemic diversity and high nearshore productivity of fossil diatom assemblages from the Pliocene Southern Ocean indicates that these ecosystems evolved in response to unique environmental conditions that are without analog elsewhere in the Pliocene oceans, or

  8. Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Fichot, C. G.; Benner, R.

    2012-12-01

    Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High concentrations and yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Concentrations and yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001) in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi Sea implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the central Arctic basins.

  9. NOAA GCOM-W1/AMSR2 Oceanic Environmental Products: Phase-2

    NASA Astrophysics Data System (ADS)

    Jelenak, Z.; Alsweiss, S.; Chang, P.; Park, J. Y.

    2014-12-01

    Passive microwave radiometry is a special application of microwave communications technology for the purpose of collecting Earth's electromagnetic radiation. With the use of radiometers onboard earth orbiting satellites, scientists are able to monitor the Earth's environment and climate system on both short- and long-term temporal scales with near global coverage. The Global Change Observation Mission (GCOM) is part of the Japanese Aerospace Exploration Agency (JAXA) broader commitment toward global and long-term observation of the Earth's environment. GCOM consists of two polar orbiting satellite series, GCOM-W (Water) and GCOM-C (Climate), with 1-year overlap between them for inter-calibration. AMSR2 onboard GCOM-W1 is a microwave radiometer system that measures dual polarized radiances at 6.9, 7.3, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz. It is a sun-synchronous orbiter that acquires microwave radiances by conically scanning the Earth's surface at a nominal earth incidence angle of 55 degrees that results in a wide swath of 1450 km. As a part of Joint Polar Satellite System (JPSS) program the National Oceanic and Atmospheric Administration (NOAA) GCOM-W1 product development and validation project will provide NOAA's users access to critical geophysical products derived from AMSR-2. These products, which are detailed in NOAA's JPSS Level 1 Requirements Document Supplement, include: microwave brightness temperature, total precipitable water, cloud liquid water, precipitation type/rate, sea surface temperature, and Sea Surface Wind Speed. Phase-1 of the AMSR-2 project at NOAA included inter-calibration of AMSR-2 measured brightness temperatures with the Tropical Rainfall Measuring Mission Microwave Imager as the reference radiometer. The second phase of the project utilized the calibrated brightness temperatures in a robust Bayesian network to retrieve more accurate geophysical parameters over the ocean surface. It can handle retrievals even with missing channels and

  10. Assessment of Energy Production Potential from Ocean Currents along the United States Coastline

    SciTech Connect

    Haas, Kevin A.

    2013-10-03

    Increasing energy consumption and depleting reserves of fossil fuels have resulted in growing interest in alternative renewable energy from the ocean. Ocean currents are an alternative source of clean energy due to their inherent reliability, persistence and sustainability. General ocean circulations exist in the form of large rotating ocean gyres, and feature extremely rapid current flow in the western boundaries due to the Coriolis Effect. The Gulf Stream system is formed by the western boundary current of the North Atlantic Ocean that flows along the east coastline of the United States, and therefore is of particular interest as a potential energy resource for the United States.

  11. Investigation the Behavior of Modis Ocean Color Products Under the 2008 Red Tide in the Eastern Persian Gulf

    NASA Astrophysics Data System (ADS)

    Ghanea, M.; Moradi, M.; Kabiri, K.

    2015-12-01

    package. The Strait of Hormuz was selected as the study area in the eastern part of the PG. Images including high cloud coverage (>50%) over the study area were filtered out. The classification maps of the above products were shown during RT and normal periods. Monthly variations of mentioned products were calculated for the dates before, during, and after RT appearance. The results were demonstrated as time-series diagrams. All the above calculations and presentations were performed in Matlab 7 software package. The results show that MODIS Chl-a, nFLH, and kd490 increased during the 2008 RT. Based on the feedback of these parameters under RT conditions, hybrid ocean color index (HOCI) is defined. HOCI is able to display better water variations during RT outbreak. High values of HOCI show RT affected areas.

  12. Underway Sampling of Marine Inherent Optical Properties on the Tara Oceans Expedition as a Novel Resource for Ocean Color Satellite Data Product Validation

    NASA Technical Reports Server (NTRS)

    Werdell, P. Jeremy; Proctor, Christopher W.; Boss, Emmanuel; Leeuw, Thomas; Ouhssain, Mustapha

    2013-01-01

    Developing and validating data records from operational ocean color satellite instruments requires substantial volumes of high quality in situ data. In the absence of broad, institutionally supported field programs, organizations such as the NASA Ocean Biology Processing Group seek opportunistic datasets for use in their operational satellite calibration and validation activities. The publicly available, global biogeochemical dataset collected as part of the two and a half year Tara Oceans expedition provides one such opportunity. We showed how the inline measurements of hyperspectral absorption and attenuation coefficients collected onboard the R/V Tara can be used to evaluate near-surface estimates of chlorophyll-a, spectral particulate backscattering coefficients, particulate organic carbon, and particle size classes derived from the NASA Moderate Resolution Imaging Spectroradiometer onboard Aqua (MODISA). The predominant strength of such flow-through measurements is their sampling rate-the 375 days of measurements resulted in 165 viable MODISA-to-in situ match-ups, compared to 13 from discrete water sampling. While the need to apply bio-optical models to estimate biogeochemical quantities of interest from spectroscopy remains a weakness, we demonstrated how discrete samples can be used in combination with flow-through measurements to create data records of sufficient quality to conduct first order evaluations of satellite-derived data products. Given an emerging agency desire to rapidly evaluate new satellite missions, our results have significant implications on how calibration and validation teams for these missions will be constructed.

  13. Sea ice phenology and timing of primary production pulses in the Arctic Ocean.

    PubMed

    Ji, Rubao; Jin, Meibing; Varpe, Øystein

    2013-03-01

    Arctic organisms are adapted to the strong seasonality of environmental forcing. A small timing mismatch between biological processes and the environment could potentially have significant consequences for the entire food web. Climate warming causes shrinking ice coverage and earlier ice retreat in the Arctic, which is likely to change the timing of primary production. In this study, we test predictions on the interactions among sea ice phenology and production timing of ice algae and pelagic phytoplankton. We do so using the following (1) a synthesis of available satellite observation data; and (2) the application of a coupled ice-ocean ecosystem model. The data and model results suggest that, over a large portion of the Arctic marginal seas, the timing variability in ice retreat at a specific location has a strong impact on the timing variability in pelagic phytoplankton peaks, but weak or no impact on the timing of ice-algae peaks in those regions. The model predicts latitudinal and regional differences in the timing of ice algae biomass peak (varying from April to May) and the time lags between ice algae and pelagic phytoplankton peaks (varying from 45 to 90 days). The correlation between the time lag and ice retreat is significant in areas where ice retreat has no significant impact on ice-algae peak timing, suggesting that changes in pelagic phytoplankton peak timing control the variability in time lags. Phenological variability in primary production is likely to have consequences for higher trophic levels, particularly for the zooplankton grazers, whose main food source is composed of the dually pulsed algae production of the Arctic.

  14. Climatic and oceanic forcing of new, net, and diatom production in the North Water

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Eric; Gratton, Yves; Fauchot, Juliette; Price, Neil M.

    New, net, and diatom production in the North Water were estimated during May to July 1998 from in vitro measurements of nitrate uptake and mesoscale temporal changes in the inventories of nitrate, silicate, oxygen, and inorganic carbon (DIC). Sampling stations were divided into two domains according to the position of the dominant water types: the silicate-rich Arctic water (SRAW) and Baffin Bay Water (BBW). BBW dominated in the southeast and was associated with relatively shallow upper mixed layers (UMLs) and weak horizontal advection. A phytoplankton bloom started in late April in BBW and grew slowly over 7 weeks, during which time the build-up of particulate organic nitrogen and carbon accounted for ca. 80% of the nitrate and DIC deficit, respectively. Over half of the new production (1.37 g C m -2 d -1) during this period was attributed to wind-driven replenishment of nitrate in the euphotic zone. The bloom culminated when seasonally declining winds and rising temperatures severed the UML from the deep nutrient reservoir. The same change in weather induced ice melt, stratification, and bloom development in northern SRAW, which had previously been characterized by deep UMLs. Collectively, the results imply that the timing and magnitude of blooms in the North Water are controlled by a succession of oceanic and climatic forcings. New C production in the North Water during April to July (1.11 g C m -2 d -1) was an order of magnitude higher than in adjacent waters and up to 8 times higher than in the Northeast Water polynya. As much as 80% of this production was mediated by diatoms >5 μm, suggesting potentially high and efficient C transfer to the herbivorous food web and deep waters.

  15. Western Pacific atmospheric nutrient deposition fluxes, their impact on surface ocean productivity

    NASA Astrophysics Data System (ADS)

    Martino, M.; Hamilton, D.; Baker, A. R.; Jickells, T. D.; Bromley, T.; Nojiri, Y.; Quack, B.; Boyd, P. W.

    2014-07-01

    The atmospheric deposition of both macronutrients and micronutrients plays an important role in driving primary productivity, particularly in the low-latitude ocean. We report aerosol major ion measurements for five ship-based sampling campaigns in the western Pacific from ~25°N to 20°S and compare the results with those from Atlantic meridional transects (~50°N to 50°S) with aerosols collected and analyzed in the same laboratory, allowing full incomparability. We discuss sources of the main nutrient species (nitrogen (N), phosphorus (P), and iron (Fe)) in the aerosols and their stoichiometry. Striking north-south gradients are evident over both basins with the Northern Hemisphere more impacted by terrestrial dust sources and anthropogenic emissions and the North Atlantic apparently more impacted than the North Pacific. We estimate the atmospheric supply rates of these nutrients and the potential impact of the atmospheric deposition on the tropical western Pacific. Our results suggest that the atmospheric deposition is P deficient relative to the needs of the resident phytoplankton. These findings suggest that atmospheric supply of N, Fe, and P increases primary productivity utilizing some of the residual excess phosphorus (P*) in the surface waters to compensate for aerosol P deficiency. Regional primary productivity is further enhanced via the stimulation of nitrogen fixation fuelled by the residual atmospheric iron and P*. Our stoichiometric calculations reveal that a P* of 0.1 µmol L-1 can offset the P deficiency in atmospheric supply for many months. This study suggests that atmospheric deposition may sustain ~10% of primary production in both the western tropical Pacific.

  16. Past and future climate patterns affecting temperate, sub-tropical and tropical horticultural crop production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Perennial horticultural crop production will be impacted by climate change effects on temperature, water availability, solar radiation, air pollution, and carbon dioxide. Horticultural crop value is derived from both the quantity and the quality of the harvested product; both of which are affected ...

  17. Development and Validation of New Advanced Ocean Altimetry Products From Cryosat-2 in Conventional and in SAR Mode

    NASA Astrophysics Data System (ADS)

    Cotton, D.; Gommenginger, C.; Andersen, O. B.; Boy, F.; Cancet, M.; Egido, A.; Fernandes, J.; Moreau, T.; Naeije, M.; Garcia, P.; Dinardo, S.; Benveniste, J.

    2013-12-01

    The ESA CryoSat-2 mission is the first space mission to carry a radar altimeter that can operate in Synthetic Aperture Radar (SAR) mode, as well as the more conventional Low Rate Mode (LRM), and also the SAR Interferometric mode (SARIN). Although the prime mission objective of CryoSat-2 is to monitor land and marine ice, the SAR mode capability of the CryoSat-2 SIRAL altimeter also presents the opportunity of demonstrating significant potential benefits of SAR altimetry for ocean applications. Expected performance enhancements of SAR mode include improved range precision, finer along track spatial resolution, and an improved ability to provide measurements close to the coast. The 'Cryosat Plus for Oceans' (CP4O) project is supported by ESA under the Support To Science Element Programme. CP4O started in June 2012, and will continue to June 2014. The objectives of CP4O are: to build a sound scientific basis for new scientific and operational applications of CryoSat-2 data over the open ocean, polar ocean, coastal seas and for sea-floor mapping. to generate and evaluate new methods and products that will enable the full exploitation of the capabilities of the CryoSat-2 SIRAL altimeter, and extend their application beyond the initial mission objectives. to ensure that the scientific return of the CryoSat-2 mission is maximised. This work is being carried out within four sub-themes: Open Ocean Altimetry, Coastal Zone Altimetry, Polar Ocean Altimetry, and Sea Floor Altimetry. In this presentation we provide a detailed assessment of the capability of SAR altimeter data to provide improved oceanographic measurements over the open ocean, coastal ocean and polar ocean. We describe different processing schemes applied to Cryosat-2 SAR mode data, to carry out full resolution SAR processing and SAR mode retracking, and to construct LRM-type altimeter waveforms from the SAR bursts, - so called Reduced SAR mode (RDSAR). The latter processing is important to determine if it is

  18. Regional patterns in current and future export production in the central Arctic Ocean quantified from nitrate fluxes

    NASA Astrophysics Data System (ADS)

    Randelhoff, Achim; Guthrie, John D.

    2016-08-01

    Due to severe nutrient and light limitation, the central Arctic Ocean has been characterized as a region of low primary productivity, with high retention of carbon in the surface waters. Using an in-depth analysis of published and new measurements of turbulent microstructure and high-resolution profiles of nitrate concentration, we reassess the vertical supply of nitrate to the Polar Mixed Layer and the associated export of particulate organic matter across the nitracline. We estimate annual export production to be approximately 1.5-3 g C m-2, but regional differences in both current and future potential of export production are large, with the eastern Arctic being least constrained by vertical nutrient supply and the western Arctic the most. Future changes in export production are assessed using a 1-D budget model; increases in the Atlantic sector are possibly compensated by decreases in the rest of the central Arctic Ocean such that the net change might be insignificant.

  19. Production of arabitol from glycerol: strain screening and study of factors affecting production yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glycerol is a major byproduct from biodiesel production, and developing new uses for glycerol is imperative to overall economics and sustainability of the biodiesel industry. With the aim of producing xylitol and/or arabitol as the value-added products from glycerol, 214 yeast strains, many osmotole...

  20. Nutrient regulation of bacterial production and ectoenzyme activities in the subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Donachie, Stuart P.; Christian, James R.; Karl, David M.

    Interactions between Bacteria and dissolved organic matter (DOM) in the open ocean are poorly understood. While it is likely that particular compounds may disproportionately regulate heterotrophic activity, very little is known about the underlying processes. Through 10 cruises between December 1996 and April 1998 we investigated how heterotrophic (non-pigmented) Bacteria cell production, per cell α- and β-glucosidase and leucine aminopeptidase (LAPase) activities, and 14C-glucose uptake in 0.8 μm filtered seawater (fsw) cultures at Station ALOHA (22°45'N, 158°W) responded to organic and inorganic nutrient additions (glucose, single amino acids, NH 4+, NO 3-). Bacterial cell production did not change significantly in fsw with glucose (1 μM) or single exogenous N sources (1 μM N) compared to that in fsw alone. Furthermore, there was no significant difference in heterotrophic bacterial cell production in fsw amended with organic or inorganic N, nor between that in fsw with organic N and glucose, or inorganic N and glucose. Cell production did increase significantly, however, in fsw with exogenous glucose (0.38 μM) plus 1 μM inorganic N (NH 4+) relative to that in fsw only, in fsw with glucose, and in fsw with 1 μM N as amino acids (His, Tyr, Leu). There was no significant difference between heterotrophic bacterial cell production in fsw with glucose, glucose plus amino acids, and that in fsw alone. Cell-specific LAPase activity increased significantly relative to that in unamended fsw when exogenous glucose plus NH 4+ or NO 3- were provided, but amino acids, glucose, NH 4+ or NO 3- alone had little or no effect. α-Glucosidase activity tended to increase with exogenous His and Tyr additions. Our results suggest that heterotrophic activity at Station ALOHA can be regulated by the abundance of particular compounds, regardless of their total concentrations. It appears that auxotrophy and de novo synthesis of cell protein from glucose may coexist among Bacteria

  1. Biological Heating in a Global Operational Ocean Forecast System: Using VIIRS Products and a Two-band Scheme

    NASA Astrophysics Data System (ADS)

    Kim, H. C.; Mehra, A.; Garraffo, Z. D.; Nadiga, S.; Bayler, E. J.; Behringer, D.

    2015-12-01

    A key long-term goal for the NWS/NCEP Environmental Modeling Center (EMC) is integrating biogeochemical variables within NOAA's Global Real-Time Ocean Forecast System (RTOFS-Global), implementing, as appropriate, the assimilation of relevant observations for an enhanced spectrum and accuracy of forecasts. In this initial effort, we combined VIIRS products with a recent algorithm (Lee et al., 2005) that can resolve vertical distribution of downwelling solar irradiance at two separate bands (EVIS: 400-700 nm and EIR: 700-2000 nm), and examined the heat transfer and its effects on the upper oceanic thermal structure in the operational RTOFS-Global. Our near-term future goals include: coupling of a global ocean biogeochemical model (Gregg, 2008) to the operational RTOFS-Global; and validation of free runs with VIIRS-derived ocean color products. This will eventually lead to the end-point goal, building data assimilative lower trophic ecosystem components in the context of "setting/updating baselines of daily marine ecosystem processes." Assimilation of VIIRS data will provide a unique and timely opportunity to establish a path toward ecological forecasting through biogeochemical analyses and forecasts. This proposed effort fully aligns with NOAA's ecological forecasting roadmap's objectives to: establish the infrastructure capability for operational biogeochemical modeling; quantify forecast accuracy and utility; identify gaps; and prioritize improvements in ecological products and services.

  2. Design and cost of near-term OTEC (Ocean Thermal Energy Conversion) plants for the production of desalinated water and electric power. [Ocean Thermal Energy Conversion (OTEC)

    SciTech Connect

    Rabas, T.; Panchal, C.; Genens, L.

    1990-01-01

    There currently is an increasing need for both potable water and power for many islands in the Pacific and Caribbean. The Ocean Thermal Energy Conversion (OTEC) technology fills these needs and is a viable option because of the unlimited supply of ocean thermal energy for the production of both desalinated water and electricity. The OTEC plant design must be flexible to meet the product-mix demands that can be very different from site to site. This paper describes different OTEC plants that can supply various mixes of desalinated water and vapor -- the extremes being either all water and no power or no water and all power. The economics for these plants are also presented. The same flow rates and pipe sizes for both the warm and cold seawater streams are used for different plant designs. The OTEC plant designs are characterized as near-term because no major technical issues need to be resolved or demonstrated. The plant concepts are based on DOE-sponsored experiments dealing with power systems, advanced heat exchanger designs, corrosion and fouling of heat exchange surfaces, and flash evaporation and moisture removal from the vapor using multiple spouts. In addition, the mature multistage flash evaporator technology is incorporated into the plant designs were appropriate. For the supply and discharge warm and cold uncertainties do exist because the required pipe sizes are larger than the maximum currently deployed -- 40-inch high-density polyethylene pipe at Keahole Point in Hawaii. 30 refs., 6 figs., 8 tabs.

  3. 40 CFR 63.5987 - What are my alternatives for meeting the emission limits for tire cord production affected sources?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the emission limits for tire cord production affected sources? 63.5987 Section 63.5987 Protection of... Pollutants: Rubber Tire Manufacturing Emission Limits for Tire Cord Production Affected Sources § 63.5987 What are my alternatives for meeting the emission limits for tire cord production affected sources?...

  4. Uncertainties in radiative transfer computations: consequences on the ocean color products

    NASA Astrophysics Data System (ADS)

    Dilligeard, Eric; Zagolski, Francis; Fischer, Juergen; Santer, Richard P.

    2003-05-01

    Operational MERIS (MEdium Resolution Imaging Spectrometer) level-2 processing uses auxiliary data generated by two radiative transfer tools. These two codes simulate upwelling radiances within a coupled 'Atmosphere-Ocean' system, using different approaches based on the matrix-operator method (MOMO) and the successive orders (SO) technique. Intervalidation of these two radiative transfer codes was performed in order to implement them in the MERIS level-2 processing. MOMO and SO simulations were then conducted on a set of representative test cases. Results stressed both for all test cases good agreements were observed. The scattering processes are retrieved within a few tenths of a percent. Nevertheless, some substantial discrepancies occurred if the polarization is not taken into account mainly in the Rayleigh scattering computations. A preliminary study indicates that the impact of the code inaccuracy in the water leaving radiances retrieval (a level-2 MERIS product) is large, up to 50% in relative difference. Applying the OC2 algorithm, the effect on the retrieval chlorophyll concentration is less than 10%.

  5. Modulation of oxygen production in Archaean oceans by episodes of Fe(II) toxicity

    NASA Astrophysics Data System (ADS)

    Swanner, Elizabeth D.; Mloszewska, Aleksandra M.; Cirpka, Olaf A.; Schoenberg, Ronny; Konhauser, Kurt O.; Kappler, Andreas

    2015-02-01

    Oxygen accumulated in the surface waters of the Earth's oceans and atmosphere several hundred million years before the Great Oxidation Event between 2.4 and 2.3 billion years ago. Before the Great Oxidation Event, periods of enhanced submarine volcanism associated with mantle plume events supplied Fe(II) to sea water. These periods generally coincide with the disappearance of indicators of the presence of molecular oxygen in Archaean sedimentary records. The presence of Fe(II) in the water column can lead to oxidative stress in some organisms as a result of reactions between Fe(II) and oxygen that produce reactive oxygen species. Here we test the hypothesis that the upwelling of Fe(II)-rich, anoxic water into the photic zone during the late Archaean subjected oxygenic phototrophic bacteria to Fe(II) toxicity. In laboratory experiments, we found that supplying Fe(II) to the anoxic growth medium housing a common species of planktonic cyanobacteria decreased both the efficiency of oxygenic photosynthesis and their growth rates. We suggest that this occurs because of increasing intracellular concentrations of reactive oxygen species. We use geochemical modelling to show that Fe(II) toxicity in conditions found in the late Archaean photic zone could have substantially inhibited water column oxygen production, thus decreasing fluxes of oxygen to the atmosphere. We therefore propose that the timing of atmospheric oxygenation was controlled by the timing of submarine, plume-type volcanism, with Fe(II) toxicity as the modulating factor.

  6. Identifying and Analyzing Uncertainty Structures in the TRMM Microwave Imager Precipitation Product over Tropical Ocean Basins

    NASA Technical Reports Server (NTRS)

    Liu, Jianbo; Kummerow, Christian D.; Elsaesser, Gregory S.

    2016-01-01

    Despite continuous improvements in microwave sensors and retrieval algorithms, our understanding of precipitation uncertainty is quite limited, due primarily to inconsistent findings in studies that compare satellite estimates to in situ observations over different parts of the world. This study seeks to characterize the temporal and spatial properties of uncertainty in the Tropical Rainfall Measuring Mission Microwave Imager surface rainfall product over tropical ocean basins. Two uncertainty analysis frameworks are introduced to qualitatively evaluate the properties of uncertainty under a hierarchy of spatiotemporal data resolutions. The first framework (i.e. 'climate method') demonstrates that, apart from random errors and regionally dependent biases, a large component of the overall precipitation uncertainty is manifested in cyclical patterns that are closely related to large-scale atmospheric modes of variability. By estimating the magnitudes of major uncertainty sources independently, the climate method is able to explain 45-88% of the monthly uncertainty variability. The percentage is largely resolution dependent (with the lowest percentage explained associated with a 1 deg x 1 deg spatial/1 month temporal resolution, and highest associated with a 3 deg x 3 deg spatial/3 month temporal resolution). The second framework (i.e. 'weather method') explains regional mean precipitation uncertainty as a summation of uncertainties associated with individual precipitation systems. By further assuming that self-similar recurring precipitation systems yield qualitatively comparable precipitation uncertainties, the weather method can consistently resolve about 50 % of the daily uncertainty variability, with only limited dependence on the regions of interest.

  7. Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem

    PubMed Central

    Hardman-Mountford, Nick J.; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J. W.; Aiken, Jim

    2013-01-01

    Geo-engineering proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these geo-engineering approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these geo-engineering approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative geo-engineering approaches. PMID:24132201

  8. Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem.

    PubMed

    Hardman-Mountford, Nick J; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J W; Aiken, Jim

    2013-12-06

    Geo-engineering proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these geo-engineering approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these geo-engineering approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative geo-engineering approaches.

  9. Relationships between Meiofaunal Biodiversity and Prokaryotic Heterotrophic Production in Different Tropical Habitats and Oceanic Regions

    PubMed Central

    Pusceddu, Antonio; Gambi, Cristina; Corinaldesi, Cinzia; Scopa, Mariaspina; Danovaro, Roberto

    2014-01-01

    Tropical marine ecosystems are among the most diverse of the world oceans, so that assessing the linkages between biodiversity and ecosystem functions (BEF) is a crucial step to predict consequences of biodiversity loss. Most BEF studies in marine ecosystems have been carried out on macrobenthic diversity, whereas the influence of the meiofauna on ecosystem functioning has received much less attention. We compared meiofaunal and nematode biodiversity and prokaryotic heterotrophic production across seagrass, mangrove and reef sediments in the Caribbean, Celebes and Red Seas. For all variables we report the presence of differences among habitats within the same region, and among regions within the same habitat. In all regions, the richness of meiofaunal taxa in reef and seagrass sediments is higher than in mangrove sediments. The sediments of the Celebes Sea show the highest meiofaunal biodiversity. The composition of meiofaunal assemblages varies significantly among habitats in the same region. The nematode beta diversity among habitats within the same region is higher than the beta diversity among regions. Although one site per habitat was considered in each region, these results suggest that the composition of meiofaunal assemblages varies primarily among biogeographic regions, whereas the composition of nematode assemblages varies more considerably among habitats. Meiofauna and nematode biodiversity and prokaryotic heterotrophic production, even after the removal of covariate effects linked with longitude and the quantity and nutritional quality of organic matter, are positively and linearly linked both across regions and within each habitat type. Our results confirm that meiofauna and nematode biodiversity may influence benthic prokaryotic activity, which, in turn, implies that diversity loss could have negative impacts on ecosystem functioning in these systems. PMID:24603709

  10. A guided search genetic algorithm using mined rules for optimal affective product design

    NASA Astrophysics Data System (ADS)

    Fung, Chris K. Y.; Kwong, C. K.; Chan, Kit Yan; Jiang, H.

    2014-08-01

    Affective design is an important aspect of new product development, especially for consumer products, to achieve a competitive edge in the marketplace. It can help companies to develop new products that can better satisfy the emotional needs of customers. However, product designers usually encounter difficulties in determining the optimal settings of the design attributes for affective design. In this article, a novel guided search genetic algorithm (GA) approach is proposed to determine the optimal design attribute settings for affective design. The optimization model formulated based on the proposed approach applied constraints and guided search operators, which were formulated based on mined rules, to guide the GA search and to achieve desirable solutions. A case study on the affective design of mobile phones was conducted to illustrate the proposed approach and validate its effectiveness. Validation tests were conducted, and the results show that the guided search GA approach outperforms the GA approach without the guided search strategy in terms of GA convergence and computational time. In addition, the guided search optimization model is capable of improving GA to generate good solutions for affective design.

  11. Production of cercosporin toxin by the phytopathogenic Cercospora fungi is affected by diverse environmental signals.

    PubMed

    You, Bang-Jau; Lee, Miin-Hui; Chung, Kuang-Ren

    2008-04-01

    Cercosporin is a polyketide phytotoxin produced by many phytopathogenic Cercospora spp. We investigated environmental signals that have elaborate control of cercosporin production. Light is the most critical factor for cercosporin production. Cercospora nicotianae accumulated substantial quantities of cercosporin only when grown on a particular potato dextrose agar under light but produced little cercosporin on other brands of potato dextrose agar or media with defined ingredients. In addition to light regulation, numerous factors including salts, buffers, and ions markedly affected cercosporin production. By contrast, pH had little effect on cercosporin production. Depletion or alteration of the carbon or nitrogen sources also affected cercosporin production. Production of cercosporin was elevated to varying levels by metal ions, such as cobalt, ferric, manganese, and zinc. Significant differences in cercosporin production were observed among various Cercospora species. Further, regulation of cercosporin production by phosphate buffer, ammonium, LiCl, but not metal ions appeared to occur at transcriptional levels. Expression of the genes involved in cercosporin biosynthesis and regulation decreased markedly and was closely concomitant with the amounts of cercosporin reduced as the fungus was grown on medium containing phosphate, LiCl, ammonium, or dimethyl sulfoxide. The results reveal the complexity of cercosporin production at the physiological and genetic levels. A model delineating regulatory controls of cercosporin biosynthesis is proposed and discussed.

  12. Estimating Oceanic Primary Production Using Vertical Irradiance and Chlorophyll Profiles from Ocean Gliders in the North Atlantic.

    PubMed

    Hemsley, Victoria S; Smyth, Timothy J; Martin, Adrian P; Frajka-Williams, Eleanor; Thompson, Andrew F; Damerell, Gillian; Painter, Stuart C

    2015-10-06

    An autonomous underwater vehicle (Seaglider) has been used to estimate marine primary production (PP) using a combination of irradiance and fluorescence vertical profiles. This method provides estimates for depth-resolved and temporally evolving PP on fine spatial scales in the absence of ship-based calibrations. We describe techniques to correct for known issues associated with long autonomous deployments such as sensor calibration drift and fluorescence quenching. Comparisons were made between the Seaglider, stable isotope ((13)C), and satellite estimates of PP. The Seaglider-based PP estimates were comparable to both satellite estimates and stable isotope measurements.

  13. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    NASA Astrophysics Data System (ADS)

    Pinedo-González, Paulina; West, A. Joshua; Tovar-Sánchez, Antonio; Duarte, Carlos M.; Marañón, Emilio; Cermeño, Pedro; González, Natalia; Sobrino, Cristina; Huete-Ortega, María.; Fernández, Ana; López-Sandoval, Daffne C.; Vidal, Montserrat; Blasco, Dolors; Estrada, Marta; Sañudo-Wilhelmy, Sergio A.

    2015-10-01

    The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.

  14. Purple Nutsedge Tuber Productivity as Affected by Organic Mulches in a Watermelon Production System

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research was conducted in Isabela, Puerto Rico, to determine the tuber productivity of the weed purple nutsedge (PN) and the yield of ‘Crimson Sweet' watermelon when grown with or without organic soil bed mulches [hays of millet (Pennisetum glaucum), nutsedge (Cyperus rotundus), sunnhemp (Crotalaria...

  15. Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Iglesias-Rodriguez, Maria Debora

    The oceans play a central role in the maintenance of life on Earth. Oceans provide extensive ecosystems for marine animals and plants covering two-thirds of the Earth's surface, are essential sources of food, economic activity, and biodiversity, and are central to the global biogeochemical cycles. The oceans are the largest reservoir of carbon in the Planet, and absorb approximately one-third of the carbon emissions that are released to the Earth's atmosphere as a result of human activities. Since the beginning of industrialization, humans have been responsible for the increase in one greenhouse gas, carbon dioxide (CO2), from approximately 280 parts per million (ppm) at the end of the nineteenth century to the current levels of 390ppm. As well as affecting the surface ocean pH, and the organisms living at the ocean surface, these increases in CO2 are causing global mean surface temperatures to rise.

  16. Demographic and Academic Factors Affecting Research Productivity at the University of KwaZulu-Natal

    ERIC Educational Resources Information Center

    North, D.; Zewotir, T.; Murray, M.

    2011-01-01

    Research output affects both the strength and funding of universities. Accordingly university academic staff members are under pressure to be active and productive in research. Though all academics have research interest, all are not producing research output which is accredited by the Department of Education (DOE). We analyzed the demographic and…

  17. Factors that Affect Student Motivation in a Dairy Products Elective Course

    ERIC Educational Resources Information Center

    Ismail, Baraem; Hayes, Kirby

    2005-01-01

    Student motivation is influenced by instructional approach. Motivation is a function of initiating and sustaining goal-directed behavior. The objective of this study was to identify factors (positive and negative) that affect motivation in a junior-level dairy products elective course. Student attitudes were surveyed each year half-way through the…

  18. Factors affecting pheromone production by the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and collection efficiency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several factors which might affect pheromone production by male pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae), were investigated. Included were a comparison of porous polymer adsorbents (Tenax versus Super Q), the effect of male age, the effect of time of day, the effect of mal...

  19. 75 FR 50033 - WTO Dispute Settlement Proceeding Regarding United States-Measures Affecting the Production and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-16

    ... From the Federal Register Online via the Government Publishing Office OFFICE OF THE UNITED STATES TRADE REPRESENTATIVE WTO Dispute Settlement Proceeding Regarding United States-- Measures Affecting the Production and Sale of Clove Cigarettes AGENCY: Office of the United States Trade Representative....

  20. The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans.

    PubMed

    Hamilton, Trinity L; Bryant, Donald A; Macalady, Jennifer L

    2016-02-01

    Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well-preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane-derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co-occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low-oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic photosynthesis

  1. The role of biology in planetary evolution: cyanobacterial primary production in low‐oxygen Proterozoic oceans

    PubMed Central

    Bryant, Donald A.; Macalady, Jennifer L.

    2016-01-01

    Summary Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well‐preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane‐derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O 2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co‐occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low‐oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic

  2. Net community production at Ocean Station Papa observed with nitrate and oxygen sensors on profiling floats

    NASA Astrophysics Data System (ADS)

    Plant, Joshua N.; Johnson, Kenneth S.; Sakamoto, Carole M.; Jannasch, Hans W.; Coletti, Luke J.; Riser, Stephen C.; Swift, Dana D.

    2016-06-01

    Six profiling floats equipped with nitrate and oxygen sensors were deployed at Ocean Station P in the Gulf of Alaska. The resulting six calendar years and 10 float years of nitrate and oxygen data were used to determine an average annual cycle for net community production (NCP) in the top 35 m of the water column. NCP became positive in February as soon as the mixing activity in the surface layer began to weaken, but nearly 3 months before the traditionally defined mixed layer began to shoal from its winter time maximum. NCP displayed two maxima, one toward the end of May and another in August with a summertime minimum in June corresponding to the historical peak in mesozooplankton biomass. The average annual NCP was determined to be 1.5 ± 0.6 mol C m-2 yr-1 using nitrate and 1.5 ± 0.7 mol C m-2 yr-1 using oxygen. The results from oxygen data proved to be quite sensitive to the gas exchange model used as well as the accuracy of the oxygen measurement. Gas exchange models optimized for carbon dioxide flux generally ignore transport due to gas exchange through the injection of bubbles, and these models yield NCP values that are two to three time higher than the nitrate-based estimates. If nitrate and oxygen NCP rates are assumed to be related by the Redfield model, we show that the oxygen gas exchange model can be optimized by tuning the exchange terms to reproduce the nitrate NCP annual cycle.

  3. Enhanced production of oxidised mercury over the tropical Pacific Ocean: a key missing oxidation pathway

    NASA Astrophysics Data System (ADS)

    Wang, F.; Saiz-Lopez, A.; Mahajan, A. S.; Gómez Martín, J. C.; Armstrong, D.; Lemes, M.; Hay, T.; Prados-Roman, C.

    2014-02-01

    Mercury is a contaminant of global concern. It is transported in the atmosphere primarily as gaseous elemental mercury, but its reactivity and deposition to the surface environment, through which it enters the aquatic food chain, is greatly enhanced following oxidation. Measurements and modelling studies of oxidised mercury in the polar to sub-tropical marine boundary layer (MBL) have suggested that photolytically produced bromine atoms are the primary oxidant of mercury. We report year-round measurements of elemental and oxidised mercury, along with ozone, halogen oxides (IO and BrO) and nitrogen oxides (NO2), in the MBL over the Galápagos Islands in the equatorial Pacific. Elemental mercury concentration remained low throughout the year, while higher than expected levels of oxidised mercury occurred around midday. Our results show that the production of oxidised mercury in the tropical MBL cannot be accounted for by bromine oxidation only, or by the inclusion of ozone and hydroxyl. As a two-step oxidation mechanism, where the HgBr intermediate is further oxidised to Hg(II), depends critically on the stability of HgBr, an additional oxidant is needed to react with HgBr to explain more than 50% of the observed oxidised mercury. Based on best available thermodynamic data, we show that atomic iodine, NO2, or HO2 could all play the potential role of the missing oxidant, though their relative importance cannot be determined explicitly at this time due to the uncertainties associated with mercury oxidation kinetics. We conclude that the key pathway that significantly enhances atmospheric mercury oxidation and deposition to the tropical oceans is missing from the current understanding of atmospheric mercury oxidation.

  4. Comparisons of Monthly Mean 10 M Wind Speeds from Satellites and NWP Products Over the Global Ocean

    DTIC Science & Technology

    2009-10-09

    Resolution QSCAT SSM/I NOGAPS ERA-40 NCEP Sea Winds instrument on the Quick Scatterometer Special Sensor Microwave/Imager Navy Operational...measurements with 25-point smoothing as described earlier. [25] Within the latitudes spanning the Arctic and Antarctic , no ice mask is applied in order to...ET AL.: 10 M WINDS OVER THE GLOBAL OCEAN D16109 egies that blend two or more of these products to produce improved forcing fields. [53

  5. Community production modulates coral reef pH and the sensitivity of ecosystem calcification to ocean acidification

    NASA Astrophysics Data System (ADS)

    DeCarlo, Thomas M.; Cohen, Anne L.; Wong, George T. F.; Shiah, Fuh-Kwo; Lentz, Steven J.; Davis, Kristen A.; Shamberger, Kathryn E. F.; Lohmann, Pat

    2017-01-01

    Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals, and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a 2 week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the nonbleaching period was ˜8.5, significantly elevated above that of the surrounding open ocean (˜8.0-8.1) as a consequence of daytime NEP (up to 112 mmol C m-2 h-1). Diurnal-averaged NEC was 390 ± 90 mmol CaCO3 m-2 d-1, higher than any other coral reef studied to date despite comparable calcifier cover (25%) and relatively high fleshy algal cover (19%). Coral bleaching linked to elevated temperatures significantly reduced daytime NEP by 29 mmol C m-2 h-1. pH on the reef flat declined by 0.2 units, causing a 40% reduction in NEC in the absence of pH changes in the surrounding open ocean. Our findings highlight the interactive relationship between carbonate chemistry of coral reef ecosystems and ecosystem production and calcification rates, which are in turn impacted by ocean warming. As open-ocean waters bathing coral reefs warm and acidify over the 21st century, the health and composition of reef benthic communities will play a major role in determining on-reef conditions that will in turn dictate the ecosystem response to climate change.

  6. Impact of ocean acidification on phytoplankton assemblage, growth, and DMS production following Fe-dust additions in the NE Pacific high-nutrient, low-chlorophyll waters

    NASA Astrophysics Data System (ADS)

    Mélançon, Josiane; Levasseur, Maurice; Lizotte, Martine; Scarratt, Michael; Tremblay, Jean-Éric; Tortell, Philippe; Yang, Gui-Peng; Shi, Guang-Yu; Gao, Huiwang; Semeniuk, David; Robert, Marie; Arychuk, Michael; Johnson, Keith; Sutherland, Nes; Davelaar, Marty; Nemcek, Nina; Peña, Angelica; Richardson, Wendy

    2016-03-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying iron (Fe) speciation and bioavailability or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust and set at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38 %) in the final concentration of chl a was measured compared to their nonacidified counterparts, and a 15 % reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched nonacidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria as estimated from algal pigment signatures. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  7. An assessment of phytoplankton primary productivity in the Arctic Ocean from satellite ocean color/in situ chlorophyll-a based models.

    PubMed

    Lee, Younjoo J; Matrai, Patricia A; Friedrichs, Marjorie A M; Saba, Vincent S; Antoine, David; Ardyna, Mathieu; Asanuma, Ichio; Babin, Marcel; Bélanger, Simon; Benoît-Gagné, Maxime; Devred, Emmanuel; Fernández-Méndez, Mar; Gentili, Bernard; Hirawake, Toru; Kang, Sung-Ho; Kameda, Takahiko; Katlein, Christian; Lee, Sang H; Lee, Zhongping; Mélin, Frédéric; Scardi, Michele; Smyth, Tim J; Tang, Shilin; Turpie, Kevin R; Waters, Kirk J; Westberry, Toby K

    2015-09-01

    We investigated 32 net primary productivity (NPP) models by assessing skills to reproduce integrated NPP in the Arctic Ocean. The models were provided with two sources each of surface chlorophyll-a concentration (chlorophyll), photosynthetically available radiation (PAR), sea surface temperature (SST), and mixed-layer depth (MLD). The models were most sensitive to uncertainties in surface chlorophyll, generally performing better with in situ chlorophyll than with satellite-derived values. They were much less sensitive to uncertainties in PAR, SST, and MLD, possibly due to relatively narrow ranges of input data and/or relatively little difference between input data sources. Regardless of type or complexity, most of the models were not able to fully reproduce the variability of in situ NPP, whereas some of them exhibited almost no bias (i.e., reproduced the mean of in situ NPP). The models performed relatively well in low-productivity seasons as well as in sea ice-covered/deep-water regions. Depth-resolved models correlated more with in situ NPP than other model types, but had a greater tendency to overestimate mean NPP whereas absorption-based models exhibited the lowest bias associated with weaker correlation. The models performed better when a subsurface chlorophyll-a maximum (SCM) was absent. As a group, the models overestimated mean NPP, however this was partly offset by some models underestimating NPP when a SCM was present. Our study suggests that NPP models need to be carefully tuned for the Arctic Ocean because most of the models performing relatively well were those that used Arctic-relevant parameters.

  8. An assessment of phytoplankton primary productivity in the Arctic Ocean from satellite ocean color/in situ chlorophyll‐a based models

    PubMed Central

    Matrai, Patricia A.; Friedrichs, Marjorie A. M.; Saba, Vincent S.; Antoine, David; Ardyna, Mathieu; Asanuma, Ichio; Babin, Marcel; Bélanger, Simon; Benoît‐Gagné, Maxime; Devred, Emmanuel; Fernández‐Méndez, Mar; Gentili, Bernard; Hirawake, Toru; Kang, Sung‐Ho; Kameda, Takahiko; Katlein, Christian; Lee, Sang H.; Lee, Zhongping; Mélin, Frédéric; Scardi, Michele; Smyth, Tim J.; Tang, Shilin; Turpie, Kevin R.; Waters, Kirk J.; Westberry, Toby K.

    2015-01-01

    Abstract We investigated 32 net primary productivity (NPP) models by assessing skills to reproduce integrated NPP in the Arctic Ocean. The models were provided with two sources each of surface chlorophyll‐a concentration (chlorophyll), photosynthetically available radiation (PAR), sea surface temperature (SST), and mixed‐layer depth (MLD). The models were most sensitive to uncertainties in surface chlorophyll, generally performing better with in situ chlorophyll than with satellite‐derived values. They were much less sensitive to uncertainties in PAR, SST, and MLD, possibly due to relatively narrow ranges of input data and/or relatively little difference between input data sources. Regardless of type or complexity, most of the models were not able to fully reproduce the variability of in situ NPP, whereas some of them exhibited almost no bias (i.e., reproduced the mean of in situ NPP). The models performed relatively well in low‐productivity seasons as well as in sea ice‐covered/deep‐water regions. Depth‐resolved models correlated more with in situ NPP than other model types, but had a greater tendency to overestimate mean NPP whereas absorption‐based models exhibited the lowest bias associated with weaker correlation. The models performed better when a subsurface chlorophyll‐a maximum (SCM) was absent. As a group, the models overestimated mean NPP, however this was partly offset by some models underestimating NPP when a SCM was present. Our study suggests that NPP models need to be carefully tuned for the Arctic Ocean because most of the models performing relatively well were those that used Arctic‐relevant parameters. PMID:27668139

  9. Analysis of extrinsic and intrinsic factors affecting event related desynchronization production.

    PubMed

    Takata, Yohei; Kondo, Toshiyuki; Saeki, Midori; Izawa, Jun; Takeda, Kotaro; Otaka, Yohei; It, Koji

    2012-01-01

    Recently there has been an increase in the number of stroke patients with motor paralysis. Appropriate re-afferent sensory feedback synchronized with a voluntary motor intention would be effective for promoting neural plasticity in the stroke rehabilitation. Therefore, BCI technology is considered to be a promising approach in the neuro-rehabilitation. To estimate human motor intention, an event-related desynchronization (ERD), a feature of electroencephalogram (EEG) evoked by motor execution or motor imagery is usually used. However, there exists various factors that affect ERD production, and its neural mechanism is still an open question. As a preliminary stage, we evaluate mutual effects of intrinsic (voluntary motor imagery) and extrinsic (visual and somatosensory stimuli) factors on the ERD production. Experimental results indicate that these three factors are not always additively interacting with each other and affecting the ERD production.

  10. Microphytobenthos sustain intertidal fish production in the Persian Gulf (Northern Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Shahraki, Maryam; Krumme, Uwe; Rixen, Tim

    2014-05-01

    In order to better understand the role of mangroves for fish production, we assessed the relative importance of potential food sources to fish diet in the mangrove-lined and un-vegetated intertidal creeks of Qeshm Island at the Strait of Hormuz, Persian Gulf, Northern Indian Ocean (26° N). The most abundant feeding guilds, stable carbon (δ13C) and nitrogen (δ15N) isotopic ratios of food sources and fishes as well as nutrient concentrations were determined in both sites. Detritivores were the most abundant feeding guild in both the mangrove and un-vegetated sites (41% and 81% relative abundance, respectively), followed by zooplanktivores (32%; 8%) and macrobenthivores (18%; 7%). At both sites, organic matter formed by mangrove trees contributed only up to 20% to the fish diet whereas organic carbon produced by microphytobenthos and plankton played a major role in the diet of the dominant fish species. Compared to the mangrove-lined creek, the pelagic and benthic food webs of the un-vegetated creeks were enriched in the heavier 13C and lighter 14N indicating an enhanced proportion of organic matter originally produced by benthic nitrogen-fixing cyanobacteria within food web of the un-vegetated creeks. The dominant role of cyanobacteria was also reflected in the nutrient concentrations. Relatively high nitrate and low phosphate concentrations showed the preferential capturing of phosphates that is leached from the sediments by the cyanobacteria mats leading to phosphate-limiting conditions in the un-vegetated intertidal creeks. Higher phosphate and lower nitrate concentrations suggest in turn that nitrate is, as in many other ecosystems, the factor limiting productivity of the pelagic food web in the mangrove-lined creek. Since the species richness in mangrove creeks was higher than in un-vegetated site, it is furthermore assumed that mangrove trees play an indirect role in the food web by providing a more heterogeneous substrate for associated biota, besides

  11. An evaluation of ocean color model estimates of marine primary productivity in coastal and pelagic regions across the globe

    NASA Astrophysics Data System (ADS)

    Saba, V. S.; Friedrichs, M. A. M.; Antoine, D.; Armstrong, R. A.; Asanuma, I.; Behrenfeld, M. J.; Ciotti, A. M.; Dowell, M.; Hoepffner, N.; Hyde, K. J. W.; Ishizaka, J.; Kameda, T.; Marra, J.; Mélin, F.; Morel, A.; O'Reilly, J.; Scardi, M.; Smith, W. O., Jr.; Smyth, T. J.; Tang, S.; Uitz, J.; Waters, K.; Westberry, T. K.

    2011-02-01

    Nearly half of the earth's photosynthetically fixed carbon derives from the oceans. To determine global and region specific rates, we rely on models that estimate marine net primary productivity (NPP) thus it is essential that these models are evaluated to determine their accuracy. Here we assessed the skill of 21 ocean color models by comparing their estimates of depth-integrated NPP to 1156 in situ 14C measurements encompassing ten marine regions including the Sargasso Sea, pelagic North Atlantic, coastal Northeast Atlantic, Black Sea, Mediterranean Sea, Arabian Sea, subtropical North Pacific, Ross Sea, West Antarctic Peninsula, and the Antarctic Polar Frontal Zone. Average model skill, as determined by root-mean square difference calculations, was lowest in the Black and Mediterranean Seas, highest in the pelagic North Atlantic and the Antarctic Polar Frontal Zone, and intermediate in the other six regions. The maximum fraction of model skill that may be attributable to uncertainties in both the input variables and in situ NPP measurements was nearly 72%. On average, the simplest depth/wavelength integrated models performed no worse than the more complex depth/wavelength resolved models. Ocean color models were not highly challenged in extreme conditions of surface chlorophyll-a and sea surface temperature, nor in high-nitrate low-chlorophyll waters. Water column depth was the primary influence on ocean color model performance such that average skill was significantly higher at depths greater than 250 m, suggesting that ocean color models are more challenged in Case-2 waters (coastal) than in Case-1 (pelagic) waters. Given that in situ chlorophyll-a data was used as input data, algorithm improvement is required to eliminate the poor performance of ocean color NPP models in Case-2 waters that are close to coastlines. Finally, ocean color chlorophyll-a algorithms are challenged by optically complex Case-2 waters, thus using satellite-derived chlorophyll-a to

  12. An evaluation of ocean color model estimates of marine primary productivity in coastal and pelagic regions across the globe

    NASA Astrophysics Data System (ADS)

    Saba, V. S.; Friedrichs, M. A. M.; Antoine, D.; Armstrong, R. A.; Asanuma, I.; Behrenfeld, M. J.; Ciotti, A. M.; Dowell, M.; Hoepffner, N.; Hyde, K. J. W.; Ishizaka, J.; Kameda, T.; Marra, J.; Mélin, F.; Morel, A.; O'Reilly, J.; Scardi, M.; Smith, W. O., Jr.; Smyth, T. J.; Tang, S.; Uitz, J.; Waters, K.; Westberry, T. K.

    2010-09-01

    Nearly half of the earth's photosynthetically fixed carbon derives from the oceans. To determine global and region specific rates, we rely on models that estimate marine net primary productivity (NPP) thus it is essential that these models are evaluated to determine their accuracy. Here we assessed the skill of 21 ocean color models by comparing their estimates of depth-integrated NPP to 1156 in situ 14C measurements encompassing ten marine regions including the Sargasso Sea, pelagic North Atlantic, coastal Northeast Atlantic, Black Sea, Mediterranean Sea, Arabian Sea, subtropical North Pacific, Ross Sea, West Antarctic Peninsula, and the Antarctic Polar Frontal Zone. Average model skill, as determined by root-mean square difference calculations, was lowest in the Black and Mediterranean Seas, highest in the pelagic North Atlantic and the Antarctic Polar Frontal Zone, and intermediate in the other six regions. The maximum fraction of model skill that may be attributable to uncertainties in both the input variables and in situ NPP measurements, was nearly 72%. Contrary to prior studies, ocean color models were not highly challenged in extreme conditions of surface chlorophyll-a and sea surface temperature, nor in high-nitrate low-chlorophyll waters. On average, the simplest depth/wavelength integrated models performed no worse than the more complex depth/wavelength resolved models. Water column depth (distance to coastlines) was the primary influence on ocean color model performance such that average skill was significantly higher at depths greater than 250 m, suggesting that ocean color models are more challenged in Case-2 waters (coastal) than in Case-1 (pelagic) waters. Given that in situ chlorophyll-a data was used as input data, algorithm improvement is required to eliminate the poor performance of ocean color models in Case-2 waters that are close to coastlines. Finally, ocean color chlorophyll-a algorithms are challenged by optically complex Case-2 waters

  13. Climate Change Response of Ocean Net Primary Production (NPP) and Export Production (EP) Regulated by Stratification Increases in The CMIP5 models

    NASA Astrophysics Data System (ADS)

    Fu, W.; Randerson, J. T.; Moore, J. K.

    2014-12-01

    Ocean warming due to rising atmospheric CO2 has increasing impacts on ocean ecosystems by modifying the ecophysiology and distribution of marine organisms, and by altering ocean circulation and stratification. We explore ocean NPP and EP changes at the global scale with simulations performed in the framework of the fifth Coupled Model Inter-comparison Project (CMIP5). Global NPP and EP are reduced considerably by the end of the century for the representative concentration pathway (RCP) 8.5 scenario, although models differ in their significantly in their direct temperature impacts on production and remineralization. The Earth system models used here project similar NPP trends albeit the magnitudes vary substantially. In general, projected changes in the 2090s for NPP range between -2.3 to -16.2% while export production reach -7 to -18% relative to 1990s. This is accompanied by increased stratification by 17-30%. Results indicate that globally reduced NPP is closely related to increased ocean stratification (R2=0.78). This is especially the case for global export production, that seems to be mostly controlled by the increased stratification (R2=0.95). We also identify phytoplankton community impacts on these patterns, that vary across the models. The negative response of NPP to climate change may be through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. There are large disagreements among the CMIP5 models in terms of simulated nutrient and oxygen concentrations for the 1990s, and their trends over time with climate change. In addition, potentially important marine biogeochemical feedbacks on the climate system were not well represented in the CMIP5 models, including important feedbacks with aerosol deposition and the marine iron cycle, and feedbacks involving the oxygen minimum zones and the marine nitrogen cycle. Thus, these substantial reductions in primary productivity and export production over

  14. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    NASA Technical Reports Server (NTRS)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  15. Seasonal Changes in the Marine Production Cycles in Response to Changes in Arctic Sea Ice and Upper Ocean Circulation

    NASA Astrophysics Data System (ADS)

    Spitz, Y. H.; Ashjian, C. J.; Campbell, R. G.; Steele, M.; Zhang, J.

    2011-12-01

    Significant seasonal changes in arctic sea ice have been observed in recent years, characterized by unprecedented summer melt-back. As summer sea ice extent shrinks to record low levels, the peripheral seas of the Arctic Ocean are exposed much earlier to atmospheric surface heat flux, resulting in longer and warmer summers with more oceanic heat absorption. The changing seasonality in the arctic ice/ocean system will alter the timing, magnitude, duration, and pattern of marine production cycles by disrupting key trophic linkages and feedbacks in planktonic food webs. We are using a coupled pan-arctic Biology/Ice/Ocean Modeling and Assimilation System (BIOMAS) to investigate the changes in the patterns of seasonality in the arctic physical and biological system. Focus on specific regions of the Arctic, such as the Chukchi Sea, the Beaufort Sea and the adjacent central Arctic, reveals that changes in the timing of the spring bloom, its duration and the response of the secondary producers vary regionally. The major changes are, however, characterized by an earlier phytoplankton bloom and a slight increase of the biomass. In addition, the largest response in the secondary producers is seen in the magnitude of the microzooplankton concentration as well as in the period (early summer to late fall) over which the microzooplankton is present.

  16. Timing and number of colonizations but not diversification rates affect diversity patterns in hemosporidian lineages on a remote oceanic archipelago.

    PubMed

    Cornuault, Josselin; Warren, Ben H; Bertrand, Joris A M; Milá, Borja; Thébaud, Christophe; Heeb, Philipp

    2013-12-01

    Parasite diversity on remote oceanic archipelagos is determined by the number and timing of colonizations and by in situ diversification rate. In this study, we compare intra-archipelago diversity of two hemosporidian parasite genera, Plasmodium and Leucocytozoon, infecting birds of the Mascarene archipelago. Despite the generally higher vagility of Plasmodium parasites, we report a diversity of Plasmodium cytochrome b haplotypes in the archipelago much lower than that of Leucocytozoon. Using phylogenetic data, we find that this difference in diversity is consistent with differences in the timing and number of colonizations, while rates of diversification do not vary significantly between the two genera. The prominence of immigration history in explaining current diversity patterns highlights the importance of historical contingencies in driving disparate biogeographic patterns in potentially harmful blood parasites infecting island birds.

  17. Phonological similarity affects production of gestures, even in the absence of overt speech

    PubMed Central

    Nozari, Nazbanou; Göksun, Tilbe; Thompson-Schill, Sharon L.; Chatterjee, Anjan

    2015-01-01

    Highlights Does phonological similarity affect gesture production in the absence of speech?Participants produced gestures from pictures with no words presented or spoken.Same pictures and gestures but different training labels were used.Phonologically similar labels led to more errors in subsequent gestures.Thus, phonological similarity affects gesture production in the absence of speech. Are manual gestures affected by inner speech? This study tested the hypothesis that phonological form influences gesture by investigating whether phonological similarity between words that describe motion gestures creates interference for production of those gestures in the absence of overt speech. Participants learned to respond to a picture of a bottle by gesturing to open the bottle's cap, and to a picture of long hair by gesturing to twirl the hair. In one condition, the gestures were introduced with phonologically-similar labels “twist” and “twirl” (similar condition), while in the other condition, they were introduced with phonologically-dissimilar labels “unscrew” and “twirl” (dissimilar condition). During the actual experiment, labels were not produced and participants only gestured by looking at pictures. In both conditions, participants also gestured to a control pair that was used as a baseline. Participants made significantly more errors on gestures in the similar than dissimilar condition after correction for baseline differences. This finding shows the influence of phonology on gesture production in the absence of overt speech and poses new constraints on the locus of the interaction between language and gesture systems. PMID:26441724

  18. Estimating photosynthetically available radiation at the ocean surface for primary production (3P Project): modeling, evaluation, and application to global MERIS imagery

    NASA Astrophysics Data System (ADS)

    Ramon, Didier; Jolivet, Dominique; Tan, Jing; Frouin, Robert

    2016-05-01

    The goal of the Photosynthetically available radiation (PAR) for Primary Production (3P) project is to provide robust, complete, and user-friendly satellite radiation products for ecosystem modeling, carbon cycle investigations, and climate change monitoring. A specific objective is to design and distribute a daily PAR product from MERIS and potentially the recent OLCI. In view of this, a PAR algorithm, based on the NASA Ocean Biology Processing Group (OBPG) operational algorithm, has been developed. The algorithm takes into account statistical diurnal variability of clouds using 3-hourly International Satellite Cloud Climatology (ISCCP) data. The PAR modeling, simplified to accommodate the information available, is evaluated using a Monte Carlo tool that simulates the satellite radiance and corresponding daily PAR. The daily PAR estimates obtained from reduced resolution (i.e., 1 km) MERIS data are evaluated against in situ measurements routinely collected from fixed buoys and platforms, namely BOUSSOLE in the Mediterranean Sea, CCE- 1 and -2 off the West coast of the United States, and COVE in the coastal Atlantic Ocean. The agreement between estimated and measured values is good on a daily time scale and substantially improved on a monthly time scale, with a bias of 2.7 (7.7%) E/m2/day and RMS errors of 8.5 (24.9%) and 4.5 (12.9%) E/m2/day. The bias is reduced significantly (by 1.8%) when using diurnal cloud climatology. Overestimation in cloudy conditions is partly explained by decoupling the clear atmosphere from the cloud/surface layer. Large gaps in regions affected by sun glint (not processed because incorrectly interpreted as cloudy) are adequately filled in the monthly PAR imagery. The statistical performance is satisfactory for long-term studies of aquatic primary production, especially in view of the much larger uncertainties on the fraction of PAR absorbed by live algae and the quantum yield of carbon fixation.

  19. 40 CFR Table 4 to Subpart III of... - Compliance Requirements for Slabstock Foam Production Affected Sources Complying With the Source...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Foam Production Affected Sources Complying With the Source-Wide Emission Limitation 4 Table 4 to... Standards for Hazardous Air Pollutants for Flexible Polyurethane Foam Production Pt. 63, Subpt. III, Table 4 Table 4 to Subpart III of Part 63—Compliance Requirements for Slabstock Foam Production Affected...

  20. Does Dietary Mitigation of Enteric Methane Production Affect Rumen Function and Animal Productivity in Dairy Cows?

    PubMed Central

    Veneman, Jolien B.; Muetzel, Stefan; Hart, Kenton J.; Faulkner, Catherine L.; Moorby, Jon M.; Perdok, Hink B.; Newbold, Charles J.

    2015-01-01

    It has been suggested that the rumen microbiome and rumen function might be disrupted if methane production in the rumen is decreased. Furthermore concerns have been voiced that geography and management might influence the underlying microbial population and hence the response of the rumen to mitigation strategies. Here we report the effect of the dietary additives: linseed oil and nitrate on methane emissions, rumen fermentation, and the rumen microbiome in two experiments from New Zealand (Dairy 1) and the UK (Dairy 2). Dairy 1 was a randomized block design with 18 multiparous lactating cows. Dairy 2 was a complete replicated 3 x 3 Latin Square using 6 rumen cannulated, lactating dairy cows. Treatments consisted of a control total mixed ration (TMR), supplementation with linseed oil (4% of feed DM) and supplementation with nitrate (2% of feed DM) in both experiments. Methane emissions were measured in open circuit respiration chambers and rumen samples were analyzed for rumen fermentation parameters and microbial population structure using qPCR and next generation sequencing (NGS). Supplementation with nitrate, but not linseed oil, decreased methane yield (g/kg DMI; P<0.02) and increased hydrogen (P<0.03) emissions in both experiments. Furthermore, the effect of nitrate on gaseous emissions was accompanied by an increased rumen acetate to propionate ratio and consistent changes in the rumen microbial populations including a decreased abundance of the main genus Prevotella and a decrease in archaeal mcrA (log10 copies/ g rumen DM content). These results demonstrate that methane emissions can be significantly decreased with nitrate supplementation with only minor, but consistent, effects on the rumen microbial population and its function, with no evidence that the response to dietary additives differed due to geography and different underlying microbial populations. PMID:26509835

  1. Modeling Oceanic Primary Production: Photoacclimation and Nutrient Effects on Light-saturated Photosynthesis

    NASA Technical Reports Server (NTRS)

    Behrenfeld, Michael J.; Maranon, Emilio; Siegel, David A.; Hooker, Stanford B.

    2000-01-01

    In this report, we describe a new model (the 'PhotoAcc' model) for estimating changes in the light-saturated rate of chlorophyll-normalized phytoplankton carbon fixation (Pbmax). The model is based on measurements conducted during the Atlantic Meridional Transect studies and the Bermuda Time Series program. The PhotoAcc model explained 64% to 82% of the observed variability in Pbmax for our data set, whereas none of the previously published Pbmax models described over the past 44 years explained any of the variance. The significance of this result is that a primary limiting factor for extracting ocean carbon fixation rates from satellite measurements of near surface chlorophyll has been errors in the estimate of Pbmax. Our new model should thus result in much improved calculations of oceanic photosynthesis and thus the role of the oceans in the global carbon cycle.

  2. Quality and safety aspects of meat products as affected by various physical manipulations of packaging materials.

    PubMed

    Lee, Keun Taik

    2010-09-01

    This article explores the effects of physically manipulated packaging materials on the quality and safety of meat products. Recently, innovative measures for improving quality and extending the shelf-life of packaged meat products have been developed, utilizing technologies including barrier film, active packaging, nanotechnology, microperforation, irradiation, plasma and far-infrared ray (FIR) treatments. Despite these developments, each technology has peculiar drawbacks which will need to be addressed by meat scientists in the future. To develop successful meat packaging systems, key product characteristics affecting stability, environmental conditions during storage until consumption, and consumers' packaging expectations must all be taken into consideration. Furthermore, the safety issues related to packaging materials must also be taken into account when processing, packaging and storing meat products.

  3. Sea-surface temperature and salinity product comparison against external in situ data in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Stroh, J. N.; Panteleev, Gleb; Kirillov, Sergey; Makhotin, Mikhail; Shakhova, Natalia

    2015-11-01

    Sea-surface temperature and salinity (SST/S) in the Arctic Ocean (AO) are largely governed by sea-ice and continental runoff rather than evaporation and precipitation as in lower latitude oceans, and global satellite analyses and models which incorporate remotely observed SST/S may be inaccurate in the AO due to lack of direct measurements for calibrating satellite data. For this reason, we are motivated to validate several satellite sea-surface temperature (SST) data products and SST/S models by comparing gridded data in the AO with oceanographic records from 2006 to 2013. Statistical analysis of product-minus-observation differences reveals that the satellite SST products considered have a temperature bias magnitude of less than 0.5°C compared to ship-based CTD measurements, and most of these biases are negative in sign. SST/S models also show an overall negative temperature bias, but no common sign or magnitude of salinity bias against CTD data. Ice tethered profiler (ITP) near-surface data span the seasons of several years, and these measurements reflect a sea-ice dominated region where the ocean surface cannot be remotely observed. Against this data, many of the considered models and products show large errors with detectable seasonal differences in SST bias. Possible sources of these errors are discussed, and two adjustments of product SST on the basis of sea-ice concentration are suggested for reducing bias to within less than 0.01°C of ITP near-surface temperatures.

  4. Precessional control on ocean productivity in the Western Pacific Warm Pool for the last 400 kyr: Insight from biogenic magnetite

    NASA Astrophysics Data System (ADS)

    Yamazaki, Toshitsugu; Horiuchi, Kazuho

    2016-11-01

    Western Pacific Warm Pool plays a significant role in large-scale atmospheric circulation and global hydrology. We conducted an environmental magnetic study of two late Pleistocene sediment cores from the western equatorial Pacific Ocean offshore of New Guinea in order to better constrain climatic and oceanographic variability, particularly spatiotemporal ocean productivity variations. Magnetic property measurements and transmission electron microscopy reveal that the magnetic mineral assemblages in the studied sediments are a mixture of biogenic and terrigenous magnetite. Variations in the acid soluble sediment component, interpreted as carbonate content, and the proportion of biogenic to terrigenous magnetite estimated from the ratio of anhysteretic to saturation remanent magnetizations are in-phase with northern hemisphere summer insolation variations. We interpret that ocean productivity increased during insolation maxima, which induced higher populations of magnetotactic bacteria through a larger nutrient supply to the seafloor. This interpretation assumes that magnetotactic bacterial populations are greatest in sediments just below the seafloor. Precessional frequencies in magnetic mineral concentration variations are suppressed after correction for carbonate dilution, whereas cyclic changes with a ˜100 kyr periodicity remain in carbonate-free magnetic concentration variations. Glacial/interglacial changes in bottom water currents may have influenced transportation and deposition of magnetic minerals. We demonstrate the usefulness of magnetic proxies for paleoceanographic studies, particularly of biogenic magnetite proxies for estimating paleoproductivity variations.

  5. Heat advection processes leading to El Niño events as depicted by an ensemble of ocean assimilation products

    NASA Astrophysics Data System (ADS)

    Ballester, Joan; Bordoni, Simona; Petrova, Desislava; Rodó, Xavier

    2016-06-01

    The oscillatory nature of El Niño-Southern Oscillation results from an intricate superposition of near-equilibrium balances and out-of-phase disequilibrium processes between the ocean and the atmosphere. The main objective of the present work is to perform an exhaustive spatiotemporal analysis of the upper ocean heat budget in an ensemble of state-of-the-art ocean assimilation products. We put specific emphasis on the ocean heat advection mechanisms, and their representation in individual ensemble members and in the different stages of the ENSO oscillation leading to EN events. Our analyses consistently show that the initial subsurface warming in the western equatorial Pacific is advected to the central Pacific by the equatorial undercurrent, which, together with the equatorward advection associated with anomalies in both the meridional temperature gradient and circulation at the level of the thermocline, explains the heat buildup in the central Pacific during the recharge phase. We also find that the recharge phase is characterized by an increase of meridional tilting of the thermocline, as well as a southward upper-ocean cross-equatorial mass transport resulting from Ekman-induced anomalous vertical motion in the off-equatorial regions. Although differences between data sets are generally small, and anomalies tend to have the same sign, the differences in the magnitude of the meridional term are seen to be key for explaining the different propagation speed of the subsurface warming tendency along the thermocline. The only exception is GECCO, which does not produce the patterns of meridional surface Ekman divergence (subsurface Sverdrup convergence) in the western and central equatorial Pacific.

  6. Enhanced production of oxidised mercury over the tropical Pacific Ocean: a key missing oxidation pathway

    NASA Astrophysics Data System (ADS)

    Wang, F.; Saiz-Lopez, A.; Mahajan, A. S.; Gómez Martín, J. C.; Armstrong, D.; Lemes, M.; Hay, T.; Prados-Roman, C.

    2013-08-01

    Mercury is a contaminant of global concern. It is transported in the atmosphere primarily as gaseous elemental mercury, but its reactivity and deposition to the surface environment, through which it enters the aquatic food chain, is greatly enhanced following oxidation. Measurements of oxidised mercury in the polar to sub-tropical marine boundary layer have suggested that photolytically produced bromine atoms are the primary oxidant of mercury. We report year-round measurements of elemental and oxidised mercury, along with ozone, halogen oxides (IO and BrO) and nitrogen oxides (NO2), in the marine boundary layer over the Galápagos Islands in the Equatorial Pacific. Elemental mercury concentration remained low throughout the year, while considerable concentrations of oxidised mercury occurred around midday. Our results show that the production of oxidised mercury in the tropical marine boundary layer cannot be accounted for by only bromine oxidation, or by the inclusion of ozone and hydroxyl. A two-step oxidation mechanism where the HgBr intermediate is further oxidised to Hg(II) depends critically on the stability of HgBr. If the current paradigm is considered, another oxidant is needed to explain more than 50% of the observed oxidised mercury. We show that atomic iodine could play the role of the missing oxidant, explaining not only the Hg(II) levels observed, but also the daily variability. However, more recent theoretical calculations indicate that the thermal dissociation rate of HgBr is much faster, by an order of magnitude, than previously reported, which implies that only trace gases at relatively high mixing ratios forming stable complexes with HgBr (such as HO2 and NO2) could compete to generate levels of Hg(II) similar to those observed in our study. Nevertheless, the daily variability of oxidised mercury is not well accounted for by using these new theoretically estimated rates. Furthermore, correlation analysis does not support a major role of NO2 or

  7. Ocean acidification affects parameters of immune response and extracellular pH in tropical sea urchins Lytechinus variegatus and Echinometra luccunter.

    PubMed

    Leite Figueiredo, Débora Alvares; Branco, Paola Cristina; Dos Santos, Douglas Amaral; Emerenciano, Andrews Krupinski; Iunes, Renata Stecca; Shimada Borges, João Carlos; Machado Cunha da Silva, José Roberto

    2016-11-01

    The rising concentration of atmospheric CO2 by anthropogenic activities is changing the chemistry of the oceans, resulting in a decreased pH. Several studies have shown that the decrease in pH can affect calcification rates and reproduction of marine invertebrates, but little attention has been drawn to their immune response. Thus this study evaluated in two adult tropical sea urchin species, Lytechinus variegatus and Echinometra lucunter, the effects of ocean acidification over a period of 24h and 5days, on parameters of the immune response, the extracellular acid base balance, and the ability to recover these parameters. For this reason, the phagocytic capacity (PC), the phagocytic index (PI), the capacity of cell adhesion, cell spreading, cell spreading area of phagocytic amebocytes in vitro, and the coelomic fluid pH were analyzed in animals exposed to a pH of 8.0 (control group), 7.6 and 7.3. Experimental pH's were predicted by IPCC for the future of the two species. Furthermore, a recovery test was conducted to verify whether animals have the ability to restore these physiological parameters after being re-exposed to control conditions. Both species presented a significant decrease in PC, in the pH of coelomic fluid and in the cell spreading area. Besides that, Echinometra lucunter showed a significant decrease in cell spreading and significant differences in coelomocyte proportions. The recovery test showed that the PC of both species increased, also being below the control values. Even so, they were still significantly higher than those exposed to acidified seawater, indicating that with the re-establishment of the pH value the phagocytic capacity of cells tends to restore control conditions. These results demonstrate that the immune system and the coelomic fluid pH of these animals can be affected by ocean acidification. However, the effects of a short-term exposure can be reversible if the natural values ​​are re-established. Thus, the effects of

  8. Assessment of Energy Production Potential from Ocean Currents along the United States Coastline

    SciTech Connect

    Haas, Kevin

    2013-09-15

    Increasing energy consumption and depleting reserves of fossil fuels have resulted in growing interest in alternative renewable energy from the ocean. Ocean currents are an alternative source of clean energy due to their inherent reliability, persistence and sustainability. General ocean circulations exist in the form of large rotating ocean gyres, and feature extremely rapid current flow in the western boundaries due to the Coriolis Effect. The Gulf Stream system is formed by the western boundary current of the North Atlantic Ocean that flows along the east coastline of the United States, and therefore is of particular interest as a potential energy resource for the United States. This project created a national database of ocean current energy resources to help advance awareness and market penetration in ocean current energy resource assessment. The database, consisting of joint velocity magnitude and direction probability histograms, was created from data created by seven years of numerical model simulations. The accuracy of the database was evaluated by ORNL?s independent validation effort documented in a separate report. Estimates of the total theoretical power resource contained in the ocean currents were calculated utilizing two separate approaches. Firstly, the theoretical energy balance in the Gulf Stream system was examined using the two-dimensional ocean circulation equations based on the assumptions of the Stommel model for subtropical gyres with the quasi-geostrophic balance between pressure gradient, Coriolis force, wind stress and friction driving the circulation. Parameters including water depth, natural dissipation rate and wind stress are calibrated in the model so that the model can reproduce reasonable flow properties including volume flux and energy flux. To represent flow dissipation due to turbines additional turbine drag coefficient is formulated and included in the model. Secondly, to determine the reasonableness of the total power

  9. Improving Ocean Color Data Products using a Purely Empirical Approach: Reducing the Requirement for Radiometric Calibration Accuracy

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2008-01-01

    Radiometric calibration is the foundation upon which ocean color remote sensing is built. Quality derived geophysical products, such as chlorophyll, are assumed to be critically dependent upon the quality of the radiometric calibration. Unfortunately, the goals of radiometric calibration are not typically met in global and large-scale regional analyses, and are especially deficient in coastal regions. The consequences of the uncertainty in calibration are very large in terms of global and regional ocean chlorophyll estimates. In fact, stability in global chlorophyll requires calibration uncertainty much greater than the goals, and outside of modern capabilities. Using a purely empirical approach, we show that stable and consistent global chlorophyll values can be achieved over very wide ranges of uncertainty. Furthermore, the approach yields statistically improved comparisons with in situ data, suggesting improved quality. The results suggest that accuracy requirements for radiometric calibration cab be reduced if alternative empirical approaches are used.

  10. Modeling UV-B Effects on Primary Production Throughout the Southern Ocean Using Multi-Sensor Satellite Data

    NASA Technical Reports Server (NTRS)

    Lubin, Dan

    2001-01-01

    This study has used a combination of ocean color, backscattered ultraviolet, and passive microwave satellite data to investigate the impact of the springtime Antarctic ozone depletion on the base of the Antarctic marine food web - primary production by phytoplankton. Spectral ultraviolet (UV) radiation fields derived from the satellite data are propagated into the water column where they force physiologically-based numerical models of phytoplankton growth. This large-scale study has been divided into two components: (1) the use of Total Ozone Mapping Spectrometer (TOMS) and Special Sensor Microwave Imager (SSM/I) data in conjunction with radiative transfer theory to derive the surface spectral UV irradiance throughout the Southern Ocean; and (2) the merging of these UV irradiances with the climatology of chlorophyll derived from SeaWiFS data to specify the input data for the physiological models.

  11. "Supergreen" Renewables: Integration of Mineral Weathering Into Renewable Energy Production for Air CO2 Removal and Storage as Ocean Alkalinity

    NASA Astrophysics Data System (ADS)

    Rau, G. H.; Carroll, S.; Ren, Z. J.

    2015-12-01

    Excess planetary CO2 and accompanying ocean acidification are naturally mitigated on geologic time scales via mineral weathering. Here, CO2 acidifies the hydrosphere, which then slowly reacts with silicate and carbonate minerals to produce dissolved bicarbonates that are ultimately delivered to the ocean. This alkalinity not only provides long-term sequestration of the excess atmospheric carbon, but it also chemically counters the effects of ocean acidification by stabilizing or raising pH and carbonate saturation state, thus helping rebalance ocean chemistry and preserving marine ecosystems. Recent research has demonstrated ways of greatly accelerating this process by its integration into energy systems. Specifically, it has been shown (1) that some 80% of the CO2 in a waste gas stream can be spontaneously converted to stable, seawater mineral bicarbonate in the presence of a common carbonate mineral - limestone. This can allow removal of CO2 from biomass combustion and bio-energy production while generating beneficial ocean alkalinity, providing a potentially cheaper and more environmentally friendly negative-CO2-emissions alternative to BECCS. It has also been demonstrated that strong acids anodically produced in a standard saline water electrolysis cell in the formation of H2 can be reacted with carbonate or silicate minerals to generate strong base solutions. These solutions are highly absorptive of air CO2, converting it to mineral bicarbonate in solution. When such electrochemical cells are powered by non-fossil energy (e.g. electricity from wind, solar, tidal, biomass, geothermal, etc. energy sources), the system generates H2 that is strongly CO2-emissions-negative, while producing beneficial marine alkalinity (2-4). The preceding systems therefore point the way toward renewable energy production that, when tightly coupled to geochemical mitigation of CO2 and formation of natural ocean "antacids", forms a high capacity, negative-CO2-emissions, "supergreen

  12. Bacterial Production and Enzymatic Activities in Deep-Sea Sediments of the Pacific Ocean: Biogeochemical Implications of Different Temperature Constraints

    NASA Astrophysics Data System (ADS)

    Danovaro, R.; Corinaldesi, C.; dell'Anno, A.

    2002-12-01

    The deep-sea bed, acting as the ultimate sink for organic material derived from the upper oceans primary production, is now assumed to play a key role in biogeochemical cycling of organic matter on global scale. Early diagenesis of organic matter in marine sediments is dependent upon biological processes (largely mediated by bacterial activity) and by molecular diffusion. Organic matter reaching the sea floor by sedimentation is subjected to complex biogeochemical transformations that make organic matter largely unsuitable for direct utilization by benthic heterotrophs. Extracellular enzymatic activities in the sediment is generally recognized as the key step in the degradation and utilization of organic polymers by bacteria and a key role in biopolymeric carbon mobilization is played by aminopeptidase, alkaline phosphatase and glucosidase activities. In the present study we investigated bacterial density, bacterial C production and exo-enzymatic activities (aminopeptidase, glucosidase and phosphatase activity) in deep-sea sediments of the Pacific Ocean in relation with the biochemical composition of sediment organic matter (proteins, carbohydrates and lipids), in order to gather information on organic matter cycling and diagenesis. Benthic viral abundance was also measured to investigate the potential role of viruses on microbial loop functioning. Sediment samples were collected at eight stations (depth ranging from 2070-3100 m) along two transects located at the opposite side (north and south) of ocean seismic ridge Juan Fernandez (along latitudes 33° 20' - 33° 40'), constituted by the submerged vulcanoes, which connects the Chilean coasts to Rapa Nui Island. Since the northern and southern sides of this ridge apparently displayed small but significant differences in deep-sea temperature (related to the general ocean circulation), this sampling strategy allowed also investigating the role of different temperature constraints on bacterial activity and

  13. Manure phosphorus extractability as affected by aluminum- and iron by-products and aerobic composting.

    PubMed

    Dao, T H; Sikora, L J; Hamasaki, A; Chaney, R L

    2001-01-01

    Shifts in manure phosphorus (P) chemical forms and pool sizes induced by water treatment residuals and industrial mineral by-products are largely undefined. We conducted a manure P fractionation study to determine mechanisms of reduction of dissolved reactive phosphorus (DRP) in poultry manure upon mineral by-product additions. The effects of composting on the P immobilization efficacy of the by-products were determined using laboratory self-heating composting simulators. The mineral by-products included an aluminum-water treatment residual (Al-WTR) and an iron-rich titanium-processing by-product. The noncomposted manure averaged 0.11 g g(-1) of total P as DRP forms. The by-products significantly reduced manure DRP, by an average of 39 and 48% in the Al- and the Fe-treated manure, respectively. The by-products also reduced the 0.5 M NH4F-extractable phosphorus (FEP) fraction. Shifts in P forms between FEP and 0.1 M NaOH-extractable phosphorus (SHEP) depended upon the Al and Fe contents of the by-products while the combined FEP + SHEP pool remained constant. Phosphate sorption measurements supported the observations that the Fe-rich by-product was more effective at reducing manure DRP and enhancing the formation of SHEP forms at the expense of FEP than the Al-WTR. Composting had no effect on the efficacy of either by-product to reduce DRP. Potential mechanisms of enhanced P stabilization in treated manure upon composting included chemical shifts from the DRP and FEP fractions to the citrate-bicarbonate-dithionite extractable P fraction. Thus, the choice of P immobilization agents affected the stability of immobilized P forms and should be taken into consideration in developing manure processing and nutrient stabilization methods.

  14. Regional estimates of reef carbonate dynamics and productivity Using Landsat 7 ETM+, and potential impacts from ocean acidification

    USGS Publications Warehouse

    Moses, C.S.; Andrefouet, S.; Kranenburg, C.; Muller-Karger, F. E.

    2009-01-01

    Using imagery at 30 m spatial resolution from the most recent Landsat satellite, the Landsat 7 Enhanced Thematic Mapper Plus (ETM+), we scale up reef metabolic productivity and calcification from local habitat-scale (10 -1 to 100 km2) measurements to regional scales (103 to 104 km2). Distribution and spatial extent of the North Florida Reef Tract (NFRT) habitats come from supervised classification of the Landsat imagery within independent Landsat-derived Millennium Coral Reef Map geomorphologic classes. This system minimizes the depth range and variability of benthic habitat characteristics found in the area of supervised classification and limits misclassification. Classification of Landsat imagery into 5 biotopes (sand, dense live cover, sparse live cover, seagrass, and sparse seagrass) by geomorphologic class is >73% accurate at regional scales. Based on recently published habitat-scale in situ metabolic measurements, gross production (P = 3.01 ?? 109 kg C yr -1), excess production (E = -5.70 ?? 108 kg C yr -1), and calcification (G = -1.68 ?? 106 kg CaCO 3 yr-1) are estimated over 2711 km2 of the NFRT. Simple models suggest sensitivity of these values to ocean acidification, which will increase local dissolution of carbonate sediments. Similar approaches could be applied over large areas with poorly constrained bathymetry or water column properties and minimal metabolic sampling. This tool has potential applications for modeling and monitoring large-scale environmental impacts on reef productivity, such as the influence of ocean acidification on coral reef environments. ?? Inter-Research 2009.

  15. Research and operational products from the combination of a monthly hydrographic station and an oceanic buoy: The Biscay AGL fixed-point water column observatory.

    NASA Astrophysics Data System (ADS)

    Lavin, Alicia; Cano, Daniel; González-Pola, Cesar; Tel, Elena; Rodriguez, Carmen; Ruiz, Manuel; Somavilla, Raquel

    2015-04-01

    Long term time series are an important tool for increasing the knowledge of ocean processes as well as for studying water masses variability in different time scales and changes and tendencies in marine ecosystems. Time series has been classically obtained by oceanographic ships that regularly cover standard sections and stations. From 1991, shelf and slope waters of the Southern Bay of Biscay are regularly sampled in a monthly hydrographic line north of Santander to a depth of 1000 m in early stages and for the whole water column down to 2580 m in recent times. Nearby, in June 2007, the IEO deployed an oceanic-meteorological buoy (AGL Buoy, 43° 50.67'N; 3° 46.20'W, and 40 km offshore, www.boya-agl.st.ieo.es). The long-term hydrographical record have allowed to define the seasonality, trends, and interannual variability at all levels, including the mixing layer and the main water masses North Atlantic Central Water and Mediterranean Water. The relation of these changes with high frequency surface conditions has been examined using the AGL buoy data from 2007 as well as satellite and reanalysis data. On that context and using that combination of sources, some products and quality controlled series of high interest and utility for scientific purposes have been developed and are offered hourly in the web page. Main products obtained are: SST and SSS anomalies, wave significant height character with respect to monthly average, and currents with respect to seasonal averages. Ocean-atmosphere heat fluxes (latent and sensible) are computed from the buoy atmospheric and oceanic measurements. Estimations of the mixed layer depth and bulk series at different water levels are provided in a monthly basis. Quality controlled series are provided for sea surface salinity, oxygen and chlorophyll data. Some sensors are particularly affected by biofouling, and monthly visits to the buoy permit to follow these sensors behaviour. Chlorophyll-fluorescence sensor is the main concern

  16. Respiration of Mediterranean cold-water corals is not affected by ocean acidification as projected for the end of the century

    NASA Astrophysics Data System (ADS)

    Maier, C.; Bils, F.; Weinbauer, M. G.; Watremez, P.; Peck, M. A.; Gattuso, J.-P.

    2013-08-01

    The rise of CO2 has been identified as a major threat to life in the ocean. About one-third of the anthropogenic CO2 produced in the last 200 yr has been taken up by the ocean, leading to ocean acidification. Surface seawater pH is projected to decrease by about 0.4 units between the pre-industrial revolution and 2100. The branching cold-water corals Madrepora oculata and Lophelia pertusa are important, habitat-forming species in the deep Mediterranean Sea. Although previous research has investigated the abundance and distribution of these species, little is known regarding their ecophysiology and potential responses to global environmental change. A previous study indicated that the rate of calcification of these two species remained constant up to 1000 μatm CO2, a value that is at the upper end of changes projected to occur by 2100. We examined whether the ability to maintain calcification rates in the face of rising pCO2 affected the energetic requirements of these corals. Over the course of three months, rates of respiration were measured at a pCO2 ranging between 350 and 1100 μatm to distinguish between short-term response and longer-term acclimation. Respiration rates ranged from 0.074 to 0.266 μmol O2 (g skeletal dry weight)-1 h-1 and 0.095 to 0.725 μmol O2 (g skeletal dry weight)-1 h-1 for L. pertusa and M. oculata, respectively, and were independent of pCO2. Respiration increased with time likely due to regular feeding, which may have provided an increased energy supply to sustain coral metabolism. Future studies are needed to confirm whether the insensitivity of respiration to increasing pCO2 is a general feature of deep-sea corals in other regions.

  17. Respiration of Mediterranean cold-water corals is not affected by ocean acidification as projected for the end of the century

    NASA Astrophysics Data System (ADS)

    Maier, C.; Bils, F.; Weinbauer, M. G.; Watremez, P.; Peck, M. A.; Gattuso, J.-P.

    2013-05-01

    The rise of CO2 has been identified as a major threat to life in the ocean. About one-third of the anthropogenic CO2 produced in the last 200 yr has been taken up by the ocean, leading to ocean acidification. Surface seawater pH is projected to decrease by about 0.4 unit between the pre-industrial revolution and 2100. The branching cold-water corals Madrepora oculata and Lophelia pertusa are important, habitat-forming species in the deep Mediterranean Sea. Although previous research has investigated the abundance and distribution of these species, little is known regarding their ecophysiology and potential responses to global environmental change. A previous study indicated that the rate of calcification of these two species remained constant up to 1000 μatm CO2 a value that is at the upper end of changes projected to occur by 2100. We examined whether the ability to maintain calcification rates in the face of rising pCO2 affected the energetic requirements of these corals. Over the course of three months, rates of respiration were measured at a pCO2 ranging between 350 and 1100 μatm to distinguish between short-term response and longer-term acclimation. Respiration rates ranged from 0.074 to 0.266 μmol O2 (g skeletal dry weight)-1 h-1 and 0.095 to 0.725 μmol O2 (g skeletal dry weight)-1 h-1 for L. and M. oculata, respectively, and were independent of pCO2. Respiration increased with time likely due to regular feeding which may have provided an increased energy supply to sustain coral metabolism. Future studies are needed to confirm whether the insensitivity of respiration to increasing pCO2 is a general feature of deep-sea corals in other regions.

  18. A general ecosystem model for applications to primary productivity and carbon cycle studies in the global oceans

    NASA Astrophysics Data System (ADS)

    Kantha, Lakshmi H.

    We have developed a general 1-D multi-component ecosystem model that incorporates a skillful upper ocean mixed layer model based on second moment closure of turbulence. The model is intended for eventual incorporation into coupled 3-D physical-biogeochemical ocean models with potential applications to modeling and studying primary productivity and carbon cycling in the global oceans as well as to promote the use of chlorophyll concentrations, in concert with satellite-sensed ocean color, as a diagnostic tool to delineate circulation features in numerical circulation models. The model is nitrogen-based and the design is deliberately general enough and modular to enable many of the existing ecosystem model formulations to be simulated and hence model-to-model comparisons rendered feasible. In its more general form (GEM10), the model solves for nitrate, ammonium, dissolved nitrogen, bacteria and two size categories of phytoplankton, zooplankton and detritus, in addition to solving for dissolved inorganic carbon and total alkalinity to enable estimation of the carbon dioxide flux at the air-sea interface. Dissolved oxygen is another prognostic variable enabling air-sea exchange of oxygen to be calculated. For potential applications to HNLC regions where productivity is constrained by the availability of a trace constituent such as iron, the model carries the trace constituent as an additional prognostic variable. Here we present 1-D model simulations for the Black Sea, Station PAPA and the BATS site. The Black Sea simulations assimilate seasonal monthly SST, SSS and surface chlorophyll, and the seasonal modulations compare favorably with earlier work. Station PAPA simulations for 1975-1977 with GEM5 assimilating observed SST and a plausible seasonal modulation of surface chlorophyll concentration also compare favorably with earlier work and with the limited observations on nitrate and pCO 2 available. Finally, GEM5 simulations at BATS for 1985-1997 are consistent with

  19. Phytoplankton class-specific primary production in the world's oceans: Seasonal and interannual variability from satellite observations

    NASA Astrophysics Data System (ADS)

    Uitz, Julia; Claustre, Hervé; Gentili, Bernard; Stramski, Dariusz

    2010-09-01

    We apply an innovative approach to time series data of surface chlorophyll from satellite observations with SeaWiFS (Sea-viewing Wide Field-of-view Sensor) to estimate the primary production associated with three major phytoplankton classes (micro-, nano-, and picophytoplankton) within the world's oceans. Statistical relationships, determined from an extensive in situ database of phytoplankton pigments, are used to infer class-specific vertical profiles of chlorophyll a concentration from satellite-derived surface chlorophyll a. This information is combined with a primary production model and class-specific photophysiological parameters to compute global seasonal fields of class-specific primary production over a 10-year period from January 1998 through December 2007. Microphytoplankton (mostly diatoms) appear as a major contributor to total primary production in coastal upwelling systems (70%) and temperate and subpolar regions (50%) during the spring-summer season. The contribution of picophytoplankton (e.g., prokaryotes) reaches maximum values (45%) in subtropical oligotrophic gyres. Nanophytoplankton (e.g., prymnesiophytes) provide a ubiquitous, substantial contribution (30-60%). Annual global estimates of class-specific primary production amount to 15 Gt C yr-1 (32% of total), 20 Gt C yr-1 (44%) and 11 Gt C yr-1 (24%) for micro-, nano-, and picophytoplankton, respectively. The analysis of interannual variations revealed large anomalies in class-specific primary production as compared to the 10-year mean cycle in both the productive North Atlantic basin and the more stable equatorial Pacific upwelling. Microphytoplankton show the largest range of variability of the three phytoplankton classes on seasonal and interannual time scales. Our results contribute to an understanding and quantification of carbon cycle in the ocean.

  20. A review on factors affecting microcystins production by algae in aquatic environments.

    PubMed

    Dai, Ruihua; Wang, Pinfei; Jia, Peili; Zhang, Yi; Chu, Xincheng; Wang, Yifei

    2016-03-01

    Microcystins, a toxin produced by Microcystis aeruginosa have become a global environmental issue in recent years. As a consequence of eutrophication, microcystins have become widely disseminated in drinking water sources, seriously impairing drinking water quality. This review focuses on the relationship between microcystins synthesis and physical, chemical, and biological environmental factors that are significant in controlling their production. Light intensity and temperature are the more important physical factors, and in many cases, an optimum level for these two factors has been observed. Nitrogen and phosphorus are the key chemical factors causing frequent occurrence of harmful algal blooms and microcystins production. The absorption of nutrients and metabolic activities of algae are affected by different concentrations and forms of nitrogen and phosphorus, leading to variations in microcystins production Metal ions and emerging pollutants are other significant chemical factors, whose comprehensive impact is still being studied. Algae can also interact with biological agents like predators and competitors in aquatic environments, and such interactions are suggested to promote MCs production and release. This review further highlights areas that require further research in order to gain a better understanding of microcystins production. It provides a theoretical basis for the control of microcystins production and releasing into aquatic environments.

  1. Factors affecting RFID adoption in the agricultural product distribution industry: empirical evidence from China.

    PubMed

    Shi, Ping; Yan, Bo

    2016-01-01

    We conducted an exploratory investigation of factors influencing the adoption of radio frequency identification (RFID) methods in the agricultural product distribution industry. Through a literature review and field research, and based on the technology-organization-environment (TOE) theoretical framework, this paper analyzes factors influencing RFID adoption in the agricultural product distribution industry in reference to three contexts: technological, organizational, and environmental contexts. An empirical analysis of the TOE framework was conducted by applying structural equation modeling based on actual data from a questionnaire survey on the agricultural product distribution industry in China. The results show that employee resistance and uncertainty are not supported by the model. Technological compatibility, perceived effectiveness, organizational size, upper management support, trust between enterprises, technical knowledge, competitive pressure and support from the Chinese government, which are supported by the model, have significantly positive effects on RFID adoption. Meanwhile, organizational size has the strongest positive effect, while competitive pressure levels have the smallest effect. Technological complexities and costs have significantly negative effects on RFID adoption, with cost being the most significantly negative influencing factor. These research findings will afford enterprises in the agricultural products supply chain with a stronger understanding of the factors that influence RFID adoption in the agricultural product distribution industry. In addition, these findings will help enterprises remain aware of how these factors affect RFID adoption and will thus help enterprises make more accurate and rational decisions by promoting RFID application in the agricultural product distribution industry.

  2. Proximity to forest edge does not affect crop production despite pollen limitation.

    PubMed

    Chacoff, Natacha P; Aizen, Marcelo A; Aschero, Valeria

    2008-04-22

    A decline in pollination function has been linked to agriculture expansion and intensification. In northwest Argentina, pollinator visits to grapefruit, a self-compatible but pollinator-dependent crop, decline by approximately 50% at 1km from forest edges. We evaluated whether this decrease in visitation also reduces the pollination service in this crop. We analysed the quantity and quality of pollen deposited on stigmas, and associated limitation of fruit production at increasing distances (edge: 10, 100, 500 and 1000m) from the remnants of Yungas forest. We also examined the quantitative and qualitative efficiency of honeybees as pollen vectors. Pollen receipt and pollen tubes in styles decreased with increasing distance from forest edge; however, this decline did not affect fruit production. Supplementation of natural pollen with self- and cross-pollen revealed that both pollen quantity and quality limited fruit production. Despite pollen limitation, honeybees cannot raise fruit production because they often do not deposit sufficient high-quality pollen per visit to elicit fruit development. However, declines in visitation frequency well below seven visits during a flower's lifespan could decrease production beyond current yields. In this context, the preservation of forest remnants, which act as pollinator sources, could contribute to resilience in crop production. Like wild plants, pollen limitation of the yield among animal-pollinated crops may be common and indicative not only of pollinator scarcity, but also of poor pollination quality, whereby pollinator efficiency, rather than just abundance, can play a broader role than previously appreciated.

  3. Spatial pattern affects diversity-productivity relationships in experimental meadow communities

    NASA Astrophysics Data System (ADS)

    Lamošová, Tereza; Doležal, Jiří; Lanta, Vojtěch; Lepš, Jan

    2010-05-01

    Plant species create aggregations of conspecifics as a consequence of limited seed dispersal, clonal growth and heterogeneous environment. Such intraspecific aggregation increases the importance of intraspecific competition relative to interspecific competition which may slow down competitive exclusion and promote species coexistence. To examine how spatial aggregation impacts the functioning of experimental assemblages of varying species richness, eight perennial grassland species of different growth form were grown in random and aggregated patterns in monocultures, two-, four-, and eight-species mixtures. In mixtures with an aggregated pattern, monospecific clumps were interspecifically segregated. Mixed model ANOVA was used to test (i) how the total productivity and productivity of individual species is affected by the number of species in a mixture, and (ii) how these relationships are affected by spatial pattern of sown plants. The main patterns of productivity response to species richness conform to other studies: non-transgressive overyielding is omnipresent (the productivity of mixtures is higher than the average of its constituent species so that the net diversity, selection and complementarity effects are positive), whereas transgressive overyielding is found only in a minority of cases (average of log(overyielding) being close to zero or negative). The theoretical prediction that plants in a random pattern should produce more than in an aggregated pattern (the distances to neighbours are smaller and consequently the competition among neighbours stronger) was confirmed in monocultures of all the eight species. The situation is more complicated in mixtures, probably as a consequence of complicated interplay between interspecific and intraspecific competition. The most productive species ( Achillea, Holcus, Plantago) were competitively superior and increased their relative productivity with mixture richness. The intraspecific competition of these species is

  4. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain (PAP) sustained observatory

    NASA Astrophysics Data System (ADS)

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; Omar, A. M.; Jeansson, E.; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-04-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m-2 d-1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production, respectively. Seasonal NCP and new production were found to be 4.57 ± 0.27 mol C m-2 and 0.37 ± 0.14 mol N m-2. The Redfield ratio was high (12), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4%, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.

  5. Air-Water Exchange of N2 and O2 from In Situ Measurements in the Subarctic and Subtropical Pacific Oceans: Oxygen Flux and Net Biological Production

    NASA Astrophysics Data System (ADS)

    Emerson, S.

    2008-12-01

    In-situ measurements of wind speed, atmospheric pressure, surface-ocean total dissolved gas pressure and oxygen concentration are used to determine the flux of nitrogen and oxygen between the ocean and atmosphere in the subarctic and subtropical Pacific Oceans. Measurements were made hourly over a period of about one year on surface moorings at the Hawaii Ocean Time series (HOT) in 2005 and at Station P in 2007. Gas pressures in the mixed layer were determined using a gas tension device (GTD) and an oxygen sensor calibrated by Winkler O2 titrations. The pressures of nitrogen and oxygen vary smoothly within a few percent of atmospheric saturation in the subtropical Pacific Ocean, but in the subarctic surface waters these values are punctuated by very rapid excursions caused by storms. The primary flux of oxygen in the upper ocean is between the ocean and atmosphere. We use a simple ocean mixed-layer model to determine this flux and estimate the net biological oxygen production at these sites. Assuming that the net biological oxygen and carbon production are stoichiometrically related over an annual cycle, this method provides a measure of the annual carbon export from the mixed layer, an important component of the ocean's role in the global carbon cycle. There is net biological O2 production most of the year in the subtropical ocean; however, little evidence of net O2 production in the wintertime in the subarctic Pacific. This contrasts with earlier 14C primary production measurements which indicate that wintertime production is about half that in summer at both locations. Annual estimates of biologically produced carbon export at these two sites will be contrasted at the presentation in the fall meeting. This research indicates that it should be possible to derive estimates of the net annual air-water oxygen fluxes caused by biological production at any location of the open ocean where there is a surface mooring. Large, abrupt atmospheric pressure changes (up to 50

  6. Fermentation Conditions that Affect Clavulanic Acid Production in Streptomyces clavuligerus: A Systematic Review

    PubMed Central

    Ser, Hooi-Leng; Law, Jodi Woan-Fei; Chaiyakunapruk, Nathorn; Jacob, Sabrina Anne; Palanisamy, Uma Devi; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

    2016-01-01

    The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO), from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g., olive oil, corn oil) could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.). Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus. PMID:27148211

  7. Preliminary study on detection sediment contamination in soil affected by the Indian Ocean giant tsunami 2004 in Aceh, Indonesia using laser-induced breakdown spectroscopy (LIBS)

    NASA Astrophysics Data System (ADS)

    Idris, Nasrullah; Ramli, Muliadi; Hedwig, Rinda; Lie, Zener Sukra; Kurniawan, Koo Hendrik

    2016-03-01

    This work is intended to asses the capability of LIBS for the detection of the tsunami sediment contamination in soil. LIBS apparatus used in this work consist of a laser system and an optical multichannel analyzer (OMA) system. The soil sample was collected from in Banda Aceh City, Aceh, Indonesia, the most affected region by the giant Indian Ocean tsunami 2004. The laser beam was focused onto surface of the soil pellet using a focusing lens to produce luminous plasma. The experiment was conducted under air as surrounding gas at 1 atmosphere. The emission spectral lines from the plasma were detected by the OMA system. It was found that metal including heavy metals can surely be detected, thus implying the potent of LIBS technique as a fast screening tools of tsunami sediment contamination.

  8. Seasonal Assessment of Biomass and Fatty Acid Productivity by Tetraselmis sp. in the Ocean Using Semi-Permeable Membrane Photobioreactors.

    PubMed

    Kim, Z-Hun; Park, Hanwool; Lee, Choul-Gyun

    2016-06-28

    A green microalga, Tetraselmis sp., was cultivated in the coastal seawater of Young-Heung Island using semi-permeable membrane photobioreactors (SPM-PBRs) in different seasons. The microalgae in the SPM-PBRs were able to grow on nutrients diffused into the PBRs from the surrounding seawater through SPMs. The biomass productivity varied depending on the ion permeabilities of the SPMs and environmental conditions, whereas the quality and quantity of fatty acids were constant. The temperature of seawater had a greater influence than solar radiation did on productivity of Tetraselmis sp. in SPM-PBRs. SPM-PBRs could provide technologies for concurrent algal biomass and fatty acids production, and eutrophication reduction in the ocean.

  9. Latitudinal variations in plankton delta C-13 - Implications for CO2 and productivity in past oceans

    NASA Technical Reports Server (NTRS)

    Rau, Greg H.; Takahashi, Taro; Des Marais, David J.

    1989-01-01

    Low C-13/C-12 in present-day Antarctic plankton has been ascribed to high CO2 availability. It is reported here, however, that this high-latitude C-13 depletion develops at CO2 partial pressures that are often below that of the present atmosphere and usually below that of equatorial upwelling systems. Nevertheless, because of much lower water temperatures and hence greater CO2 solubility at high latitude, the preceding pCO2 measurements translate into Antarctic surface-water CO2 (aq) concentrations that are as much as 2.5 times higher than in equatorial waters. It is calculated that an oceanic pCO2 level greater than 800 micro-atm is a warmer low-latitude Cretaceous ocean would have been required to produce the plankton C-13 depletion preserved in Cretaceous sediments.

  10. Comment on "Glacial cycles drive variations in the production of oceanic crust".

    PubMed

    Goff, John A

    2015-09-04

    Crowley et al. (Reports, 13 March 2015, p. 1237) propose that abyssal hill topography can be generated by variations in volcanism at mid-ocean ridges modulated by Milankovitch cycle-driven changes in sea level. Published values for abyssal hill characteristic widths versus spreading rate do not generally support this hypothesis. I argue that abyssal hills are primarily fault-generated rather than volcanically generated features.

  11. Production of sulphate-rich vapour during the Chicxulub impact and implications for ocean acidification

    NASA Astrophysics Data System (ADS)

    Ohno, Sohsuke; Kadono, Toshihiko; Kurosawa, Kosuke; Hamura, Taiga; Sakaiya, Tatsuhiro; Shigemori, Keisuke; Hironaka, Yoichiro; Sano, Takayoshi; Watari, Takeshi; Otani, Kazuto; Matsui, Takafumi; Sugita, Seiji

    2014-04-01

    The mass extinction event at the Cretaceous/Palaeogene boundary 65.5 Myr ago has been widely attributed to the Chicxulub impact, but the mechanisms of extinction remain debated. In the oceans, near-surface planktonic foraminifera suffered severe declines, in contrast to the relatively high survival rates of bottom-dwelling benthic foraminifera. The vapour produced by an impact into Chicxulub's target rocks, which include sulphate-rich anhydrite, could have led to global acid rain, which can explain the pattern of oceanic extinctions. However, it has been suggested that most of the sulphur in the target rocks would have been released as sulphur dioxide and would have stayed in the stratosphere for a long time. Here we show, from impact experiments into anhydrite at velocities exceeding 10 km s-1, that sulphur trioxide dominates over sulphur dioxide in the resulting vapour cloud. Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapour to form sulphuric acid aerosol particles. We also find, using a theoretical model of aerosol coagulation following the Chicxulub impact, that larger silicate particles ejected during the impact efficiently scavenge sulphuric acid aerosol particles and deliver the sulphuric acid to the surface within a few days. The rapid surface deposition of sulphuric acid would cause severe ocean acidification and account for preferential extinction of planktonic over benthic foraminifera.

  12. Net primary productivity estimates and environmental variables in the Arctic Ocean: An assessment of coupled physical-biogeochemical models

    NASA Astrophysics Data System (ADS)

    Lee, Younjoo J.; Matrai, Patricia A.; Friedrichs, Marjorie A. M.; Saba, Vincent S.; Aumont, Olivier; Babin, Marcel; Buitenhuis, Erik T.; Chevallier, Matthieu; de Mora, Lee; Dessert, Morgane; Dunne, John P.; Ellingsen, Ingrid H.; Feldman, Doron; Frouin, Robert; Gehlen, Marion; Gorgues, Thomas; Ilyina, Tatiana; Jin, Meibing; John, Jasmin G.; Lawrence, Jon; Manizza, Manfredi; Menkes, Christophe E.; Perruche, Coralie; Le Fouest, Vincent; Popova, Ekaterina E.; Romanou, Anastasia; Samuelsen, Annette; Schwinger, Jörg; Séférian, Roland; Stock, Charles A.; Tjiputra, Jerry; Tremblay, L. Bruno; Ueyoshi, Kyozo; Vichi, Marcello; Yool, Andrew; Zhang, Jinlun

    2016-12-01

    The relative skill of 21 regional and global biogeochemical models was assessed in terms of how well the models reproduced observed net primary productivity (NPP) and environmental variables such as nitrate concentration (NO3), mixed layer depth (MLD), euphotic layer depth (Zeu), and sea ice concentration, by comparing results against a newly updated, quality-controlled in situ NPP database for the Arctic Ocean (1959-2011). The models broadly captured the spatial features of integrated NPP (iNPP) on a pan-Arctic scale. Most models underestimated iNPP by varying degrees in spite of overestimating surface NO3, MLD, and Zeu throughout the regions. Among the models, iNPP exhibited little difference over sea ice condition (ice-free versus ice-influenced) and bottom depth (shelf versus deep ocean). The models performed relatively well for the most recent decade and toward the end of Arctic summer. In the Barents and Greenland Seas, regional model skill of surface NO3 was best associated with how well MLD was reproduced. Regionally, iNPP was relatively well simulated in the Beaufort Sea and the central Arctic Basin, where in situ NPP is low and nutrients are mostly depleted. Models performed less well at simulating iNPP in the Greenland and Chukchi Seas, despite the higher model skill in MLD and sea ice concentration, respectively. iNPP model skill was constrained by different factors in different Arctic Ocean regions. Our study suggests that better parameterization of biological and ecological microbial rates (phytoplankton growth and zooplankton grazing) are needed for improved Arctic Ocean biogeochemical modeling.

  13. 40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...: Rubber Tire Manufacturing Testing and Initial Compliance Requirements for Tire Production Affected... to determine the mass percent of HAP in cements and solvents. To determine the HAP content in the cements and solvents used at your tire production affected source, use EPA Method 311 of appendix A...

  14. 40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...: Rubber Tire Manufacturing Testing and Initial Compliance Requirements for Tire Production Affected... to determine the mass percent of HAP in cements and solvents. To determine the HAP content in the cements and solvents used at your tire production affected source, use EPA Method 311 of appendix A...

  15. 40 CFR 63.5996 - How do I demonstrate initial compliance with the emission limits for tire production affected...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... with the emission limits for tire production affected sources? 63.5996 Section 63.5996 Protection of... Pollutants: Rubber Tire Manufacturing Testing and Initial Compliance Requirements for Tire Production Affected Sources § 63.5996 How do I demonstrate initial compliance with the emission limits for...

  16. 40 CFR Table 12 to Subpart Xxxx of... - Continuous Compliance With the Emission Limits for Tire Cord Production Affected Sources

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Limits for Tire Cord Production Affected Sources 12 Table 12 to Subpart XXXX of Part 63 Protection of... Pollutants: Rubber Tire Manufacturing Pt. 63, Subpt. XXXX, Table 12 Table 12 to Subpart XXXX of Part 63—Continuous Compliance With the Emission Limits for Tire Cord Production Affected Sources As stated in §...

  17. 40 CFR 63.5986 - What emission limits must I meet for tire cord production affected sources?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... tire cord production affected sources? 63.5986 Section 63.5986 Protection of Environment ENVIRONMENTAL... POLLUTANTS FOR SOURCE CATEGORIES National Emissions Standards for Hazardous Air Pollutants: Rubber Tire Manufacturing Emission Limits for Tire Cord Production Affected Sources § 63.5986 What emission limits must...

  18. 40 CFR Table 7 to Subpart Xxxx of... - Initial Compliance With the Emission Limits for Tire Cord Production Affected Sources

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Limits for Tire Cord Production Affected Sources 7 Table 7 to Subpart XXXX of Part 63 Protection of... Pollutants: Rubber Tire Manufacturing Pt. 63, Subpt. XXXX, Table 7 Table 7 to Subpart XXXX of Part 63—Initial Compliance With the Emission Limits for Tire Cord Production Affected Sources As stated in § 63.5999,...

  19. Climate change induced rainfall patterns affect wheat productivity and agroecosystem functioning dependent on soil types

    NASA Astrophysics Data System (ADS)

    Tabi Tataw, James; Baier, Fabian; Krottenthaler, Florian; Pachler, Bernadette; Schwaiger, Elisabeth; Whylidal, Stefan; Formayer, Herbert; Hösch, Johannes; Baumgarten, Andreas; Zaller, Johann G.

    2014-05-01

    Wheat is a crop of global importance supplying more than half of the world's population with carbohydrates. We examined, whether climate change induced rainfall patterns towards less frequent but heavier events alter wheat agroecosystem productivity and functioning under three different soil types. Therefore, in a full-factorial experiment Triticum aestivum L. was cultivated in 3 m2 lysimeter plots containing the soil types sandy calcaric phaeozem, gleyic phaeozem or calcic chernozem. Prognosticated rainfall patterns based on regionalised climate change model calculations were compared with current long-term rainfall patterns; each treatment combination was replicated three times. Future rainfall patterns significantly reduced wheat growth and yield, reduced the leaf area index, accelerated crop development, reduced arbuscular mycorrhizal fungi colonisation of roots, increased weed density and the stable carbon isotope signature (δ13C) of both old and young wheat leaves. Different soil types affected wheat growth and yield, ecosystem root production as well as weed abundance and biomass. The interaction between climate and soil type was significant only for the harvest index. Our results suggest that even slight changes in rainfall patterns can significantly affect the functioning of wheat agroecosystems. These rainfall effects seemed to be little influenced by soil types suggesting more general impacts of climate change across different soil types. Wheat production under future conditions will likely become more challenging as further concurrent climate change factors become prevalent.

  20. Differential phenolic production in leaves of Vitis vinifera cv. Alvarinho affected with esca disease.

    PubMed

    Lima, Marta R M; Felgueiras, Mafalda L; Cunha, Ana; Chicau, Gisela; Ferreres, Federico; Dias, Alberto C P

    2017-03-01

    Esca is a destructive disease of complex etiology affecting grapevines worldwide. A major constraint to the study and control of esca is that the disease is not diagnosed until external leaf and/or fruit symptoms are visible; however external symptoms usually appear several years after infection onset. We studied the phenolic content of V. vinifera cv. Alvarinho leaves using high performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS)/LC-MS. Leaves from affected cordons with and without visible symptoms (diseased and apparently healthy leaves, respectively) and leaves from asymptomatic cordons (healthy leaves) were analyzed. Application of principal components analysis (PCA) to HPLC data showed a clear separation between diseased, apparently healthy, and healthy leaves, with the apparently healthy leaves clustered in a medial position. Several compounds were highly correlated with diseased leaves indicating a differential phenolic production due to esca disease in V. vinifera cv. Alvarinho leaves. Total phenolic production was shown to significantly increase in diseased leaves, compared to healthy leaves, with apparently healthy leaves containing a medial amount. Trans-caffeoyltartaric acid, trans-coumaroyl-tartaric acid, quercetin-3-O-glucoside, quercetin-3-O-galactoside, kaempferol-3-glucoside and myricetin were identified among the compounds associated with disease and their content shown to change similarly to total phenolic production. This study shows that it is possible to discriminate between diseased, healthy and apparently healthy leaves by applying PCA to HPLC data.

  1. Do non-native plant species affect the shape of productivity-diversity relationships?

    USGS Publications Warehouse

    Drake, J.M.; Cleland, E.E.; Horner-Devine, M. C.; Fleishman, E.; Bowles, C.; Smith, M.D.; Carney, K.; Emery, S.; Gramling, J.; Vandermast, D.B.; Grace, J.B.

    2008-01-01

    The relationship between ecosystem processes and species richness is an active area of research and speculation. Both theoretical and experimental studies have been conducted in numerous ecosystems. One finding of these studies is that the shape of the relationship between productivity and species richness varies considerably among ecosystems and at different spatial scales, though little is known about the relative importance of physical and biological mechanisms causing this variation. Moreover, despite widespread concern about changes in species' global distributions, it remains unclear if and how such large-scale changes may affect this relationship. We present a new conceptual model of how invasive species might modulate relationships between primary production and species richness. We tested this model using long-term data on relationships between aboveground net primary production and species richness in six North American terrestrial ecosystems. We show that primary production and abundance of non-native species are both significant predictors of species richness, though we fail to detect effects of invasion extent on the shapes of the relationship between species richness and primary production.

  2. Physical factors affecting the cost and efficiency of sound production in the treefrog Hyla versicolor.

    PubMed

    McLister, J D

    2001-01-01

    The metabolic cost, energy output and efficiency (i.e. the ratio of energy output to metabolic cost) of sound production were compared among male grey treefrogs (Hyla versicolor) as a function of body size and temperature. The effects of call length (in notes per call) and dominant frequency (in kHz) were also considered. Cost, determined from the amount of oxygen consumed, averaged 12.1 mJ per note and was dependent only upon body mass. Acoustic energy per note, determined from oscillograms of recorded calls, averaged 0.34 mJ and was dependent only upon temperature. Conventional theory suggests that the efficiency of sound production should be a function of the ratio of the linear size of the radiating structures to the wavelength of the sound generated (i.e. efficiency is assumed to be a function of the product of mass(0.33) and frequency), but efficiency in H. versicolor was found to be a function of the product of temperature(2.1) and mass(-1.08). Adjusting for temperature and body mass, the efficiency of sound production in H. versicolor (average 2.4 %) is greater than the efficiency of other frog species for which data are available. Temperature may affect acoustic energy output because trunk muscle contraction speed increases with temperature, which increases the velocity of airflow across the vocal cords.

  3. Nuclear DNA content affects the productivity of conifer forests by altering hydraulic architecture

    NASA Astrophysics Data System (ADS)

    Alday, Josu; Resco de Dios, Víctor

    2014-05-01

    Predictions of future global climate rely on feedbacks between terrestrial vegetation and the global carbon cycle, but the exact mechanisms underlying this relationship are still being discussed. One of the key knowledge gaps lies on the scaling of cellular processes to the ecosystem level. Here we examine whether an under-explored plant trait, inter-specific variation in the bulk amount of DNA in unreplicated somatic cells (2C DNA content), can explain inter-specific variation in the maximum productivity of conifer forests. We expected 2C DNA content to be negatively related to conifer productivity because: 1) it is positively correlated with cell volume (which, in turn, potentially affects structural features such as leaf mass area, a strong predictor of photosynthetic capacity); 2) it is positively correlated with stomatal size (with larger stomata leading to lower overall stomatal conductance and, by extension, lower CO2 uptake); and 3) larger genome sizes may reduce P availability in RNA (which has been hypothesized to slow growth). We present the results of regression and independent contrasts in different monospecific forests encompassing a 52º latitudinal gradient, each being dominated by 1 of 35 different conifer species. Contrary to expectations, we observed a positive correlation between genome size and maximum Gross Primary Productivity (R2 = 0.47) and also between genome size maximum tree height (R2 = 0.27). This correlation was apparently driven by the effects of genome size on stem hydraulics, since 2C DNA was positively correlated with wood density (R2 = 0.40) and also with resistance to cavitation (P50, R2 = 0.28). That is, increased genome sizes have a positive effect on the productivity of conifer forests by affecting the vascular tissues to increase their capacity for water transport. Our results shed a new light on the evolution of the vascular system of conifer forests and how they affect ecosystem productivity, and indicate the potential to

  4. Condition-dependent ejaculate production affects male mating behavior in the common bedbug Cimex lectularius.

    PubMed

    Kaldun, Bettina; Otti, Oliver

    2016-04-01

    Food availability in the environment is often low and variable, constraining organisms in their resource allocation to different life-history traits. For example, variation in food availability is likely to induce condition-dependent investment in reproduction. Further, diet has been shown to affect ejaculate size, composition and quality. How these effects translate into male reproductive success or change male mating behavior is still largely unknown. Here, we concentrated on the effect of meal size on ejaculate production, male reproductive success and mating behavior in the common bedbug Cimex lectularius. We analyzed the production of sperm and seminal fluid within three different feeding regimes in six different populations. Males receiving large meals produced significantly more sperm and seminal fluid than males receiving small meals or no meals at all. While such condition-dependent ejaculate production did not affect the number of offspring produced after a single mating, food-restricted males could perform significantly fewer matings than fully fed males. Therefore, in a multiple mating context food-restricted males paid a fitness cost and might have to adjust their mating strategy according to the ejaculate available to them. Our results indicate that meal size has no direct effect on ejaculate quality, but food availability forces a condition-dependent mating rate on males. Environmental variation translating into variation in male reproductive traits reveals that natural selection can interact with sexual selection and shape reproductive traits. As males can modulate their ejaculate size depending on the mating situation, future studies are needed to elucidate whether environmental variation affecting the amount of ejaculate available might induce different mating strategies.

  5. Does humor in radio advertising affect recognition of novel product brand names?

    PubMed

    Berg, E M; Lippman, L G

    2001-04-01

    The authors proposed that item selection during shopping is based on brand name recognition rather than recall. College students rated advertisements and news stories of a simulated radio program for level of amusement (orienting activity) before participating in a surprise recognition test. Humor level of the advertisements was varied systematically, and content was controlled. According to signal detection analysis, humor did not affect the strength of recognition memory for brand names (nonsense units). However, brand names and product types were significantly more likely to be associated when appearing in humorous advertisements than in nonhumorous advertisements. The results are compared with prior findings concerning humor and recall.

  6. Activity Book: Ocean Ecology.

    ERIC Educational Resources Information Center

    Learning, 1992

    1992-01-01

    Presents a collection of activities to help elementary students study ocean ecology. The activities have students investigate ocean inhabitants, analyze animal adaptations, examine how temperature and saltiness affect ocean creatures, and learn about safeguarding the sea. Student pages offer reproducible learning sheets. (SM)

  7. Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; d'Ovidio, F.

    2015-06-01

    The Kerguelen Plateau region in the Indian sector of the Southern Ocean supports annually a large-scale phytoplankton bloom which is naturally fertilized with iron. As part of the second Kerguelen Ocean and Plateau compared Study expedition (KEOPS2) in austral spring (October-November 2011), one CARbon Interface OCean Atmosphere (CARIOCA) buoy was deployed east of the Kerguelen Plateau. It drifted eastward downstream along the Kerguelen plume. Hourly surface measurements of pCO2, O2 and ancillary observations were collected between 1 November 2011 and 12 February 2012 with the aim of characterizing the spatial and temporal variability of the biological net community production, NCP, downstream the Kerguelen Plateau, assessing the impact of iron-induced productivity on the biological inorganic carbon consumption and consequently on the CO2 flux exchanged at the air-sea interface. The trajectory of the buoy up to mid-December was within the longitude range 72-83° E, close to the polar front and then in the polar frontal zone, PFZ, up to 97° E. From 17 November to 16 December, the buoy drifted within the Kerguelen plume following a filament carrying dissolved iron, DFe, for a total distance of 700 km. In the first part of the trajectory of the buoy, within the iron plume, the ocean surface waters were always a sink for CO2 and a source for O2, with fluxes of respective mean values equal to -8 mmol CO2 and +38 mmol O2 m-2 d-1. To the east, as the buoy escaped the iron-enriched filament, the fluxes were in the opposite direction, with respective mean values of +5 mmol CO2 and -48 mmol O2 m-2 d-1. These numbers clearly indicate the strong impact of biological processes on the biogeochemistry in the surface waters within the Kerguelen plume in November-mid-December, while it is undetectable to the east in the PFZ from mid- December to mid-February. While the buoy follows the Fe-enriched filament, simultaneous observations of dissolved inorganic carbon (DIC) and

  8. A new release 06 of the GRACE Atmosphere and Ocean De-aliasing Level-1B (AOD1B) product

    NASA Astrophysics Data System (ADS)

    Fagiolini, E.; Dobslaw, H.; Flechtner, F.; Rudenko, S.

    2014-12-01

    We present a new release 06 of the GRACE AOD1B product, intended to serve as a background model for the removal of high-frequency non-tidal mass variations due to short-term (daily and sub-daily) mass transport in the atmosphere and oceans. AOD1B shall avoid aliasing of these high frequency signals into monthly gravity models derived from modern gravity missions (CHAMP, GRACE or GRACE-FO) and shall help to consistently reprocess altimetry and SLR satellites for later combination of gravimetric and geometric results. Therefore, AOD1B RL06 will be provided for an extended time-range (from 1976 till present). Some results on the use of the new and previous releases of the AOD1B product for precise orbit determination (POD) of these satellites are presented as well. For AOD1B RL06 the ocean part is the same as in RL05, while the atmospheric one includes an improved algorithm for the vertical integration of the atmospheric columns as well as a correction strategy for errors (jumps) present in the atmospheric input data. These errors are estimated by comparing the standard atmospheric coefficients based on the ECMWF operational analysis with independently generated coefficients based on the ECMWF ERA-Interim reanalysis. With this, we are able to correct the 6-hourly AOD1B data sets applied during GRACE POD. The derived gravity solutions, as well as the monthly averages 'GAA' (atmosphere only) and 'GAC' (atmosphere combined with ocean), are then free from errors present in the atmospheric input data. Furthermore, we are checking routinely processing changes at ECMWF, since they are strictly associated with the above mentioned errors, and will estimate new correction coefficients, if necessary.

  9. Phonological Neighborhood Competition Affects Spoken Word Production Irrespective of Sentential Context

    PubMed Central

    Fox, Neal P.; Reilly, Megan; Blumstein, Sheila E.

    2015-01-01

    Two experiments examined the influence of phonologically similar neighbors on articulation of words’ initial stop consonants in order to investigate the conditions under which lexically-conditioned phonetic variation arises. In Experiment 1, participants produced words in isolation. Results showed that the voice-onset time (VOT) of a target’s initial voiceless stop was predicted by its overall neighborhood density, but not by its having a voicing minimal pair. In Experiment 2, participants read aloud the same targets after semantically predictive sentence contexts and after neutral sentence contexts. Results showed that, although VOTs were shorter in words produced after predictive contexts, the neighborhood density effect on VOT production persisted irrespective of context. These findings suggest that global competition from a word’s neighborhood affects spoken word production independently of contextual modulation and support models in which activation cascades automatically and obligatorily among all of a selected target word’s phonological neighbors during acoustic-phonetic encoding. PMID:26124538

  10. Antrodia camphorata-fermented product cultured in deep ocean water has more liver protection against thioacetamide-induced fibrosis.

    PubMed

    Wang, Li-Chun; Kuo, Iau-Uen; Tsai, Tsung-Yu; Lee, Chun-Lin

    2013-12-01

    Antrodia camphorata is a unique fungus in Taiwan; the submerged fermentation product is used as the functional food for liver protection. Deep ocean water (DOW) containing rich metals and trace elements is proven to stimulate the production of functional metabolites and health function of functional fungus product in our previous study. Therefore, A. camphorata-fermented product cultured in DOW (DOW-AC) or reverse osmosis water (ROW-AC) as culture water was daily fed thioacetamide (TAA)-induced fibrosis rat for 8 weeks in order to investigate whether DOW promoted the effect of A. camphorata-fermented product on the prevention against TAA-induced liver damage and fibrosis. In the results, feeding one dose of DOW-AC prevented from TAA-induced weight loss and had more effect on inhibiting lipid peroxidation, reactive oxygen species, iNOS, and TNF-α expression than one dose of ROW-AC. Furthermore, DOW-AC also had more potent effect on protection against TAA-induced liver damage and fibrosis according to the results of H&E stain and collagen stain. However, higher liver protection of DOW-AC should be due to the fact that DOW not only increased the production of A. camphorata-fermented functional metabolites including triterpenoids, polysaccharides, flavonoids, and polyphenols but also contributed to protection against TAA-induced damage and fibrosis.

  11. SeaWiFS on-orbit gain and detector calibrations: effect on ocean products.

    PubMed

    Eplee, Robert E; Patt, Frederick S; Franz, Bryan A; Bailey, Sean W; Meister, Gerhard; McClain, Charles R

    2007-09-20

    The NASA Ocean Biology Processing Group's Calibration and Validation Team has analyzed the mission-long Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) on-orbit gain and detector calibration time series to verify that lunar calibrations, obtained at nonstandard gains and radiance ranges, are valid for Earth data collected at standard gains and typical ocean, cloud, and land radiances. For gain calibrations, a constant voltage injected into the postdetector electronics allows gain ratios to be computed for all four detectors in each band. The on-orbit lunar gain ratio time series show small drifts for the near infrared bands. These drifts are propagated into the ocean color data through the atmospheric correction parameter epsilon, which uses the 765/865 nm band ratio. An anomaly analysis of global mean normalized water-leaving radiances at 510 nm shows a small decrease over the mission, while an analysis of epsilon shows a corresponding increase. The drifts in the lunar time series for the 765 and 865 nm bands were corrected. An analysis of the revised water-leaving radiances at 510 nm shows the drift has been eliminated, while an analysis of epsilon shows a reduced drift. For detector calibrations, solar diffuser observations made by the individual detectors in each band allows the response of the detectors to be monitored separately. The mission-long time series of detector calibration data show that the variations in the response of the individual detectors are less than 0.5% over the mission for all bands except the 865 nm band, where the variations are less than 1%.

  12. SeaWiFS on-orbit gain and detector calibrations: effect on ocean products

    SciTech Connect

    Eplee, Robert E. Jr.; Patt, Frederick S.; Franz, Bryan A.; Bailey, Sean W.; Meister, Gerhard; McClain, Charles R

    2007-09-20

    The NASA Ocean Biology Processing Group's Calibration and Validation Team has analyzed the mission-long Sea-Viewing Wide Field-of-View Sensor(SeaWiFS) on-orbit gain and detector calibration time series to verify that lunar calibrations, obtained at nonstandard gains and radiance ranges, are valid for Earth data collected at standard gains and typical ocean, cloud,and land radiances. For gain calibrations, a constant voltage injected into the postdetector electronics allows gain ratios to be computed for all four detectors in each band. The on-orbit lunar gain ratio time series show small drifts for the near infrared bands. These drifts are propagated into the ocean color data through the atmospheric correction parameter ?, which uses the765/865 nm band ratio. An anomaly analysis of global mean normalized water-leaving radiances at510 nm shows a small decrease over the mission,while an analysis of ? shows a corresponding increase. The drifts in the lunar time series for the 765 and865 nm bands were corrected. An analysis of the revised water-leaving radiances at510 nm shows the drift has been eliminated,while an analysis of ? shows a reduced drift. For detector calibrations, solar diffuser observations made by the individual detectors in each band allows the response of the detectors to be monitored separately. The mission-long time series of detector calibration data show that the variations in the response of the individual detectors are less than 0.5% over the mission for all bands except the865 nm band, where the variations are less than 1%.

  13. New Global Deep Blue Aerosol Product over Land and Ocean from VIIRS, and Its comparisons with MODIS

    NASA Astrophysics Data System (ADS)

    Hsu, N. Y. C.; Bettenhausen, C.; Sayer, A. M.; Lee, J.; Tsay, S. C.; Carletta, N.

    2015-12-01

    The impacts of natural and anthropogenic sources of air pollution on climate and human health have continued to gain attention from the scientific community. In order to facilitate these effects, high quality consistent long-term global aerosol data records from satellites are essential. Several EOS-era instruments (e.g., SeaWiFS, MODIS, and MISR) are able to provide such information with a high degree of fidelity. However, with the aging MODIS sensors and the launch of the VIIRS instrument on Suomi NPP in late 2011, the continuation of long-term aerosol data records suitable for climate studies from MODIS to VIIRS is needed urgently. VIIRS was designed to have similar capabilities to MODIS, with similar visible/infrared spectral channels, and spatial/ temporal resolution. However, small but significant differences in several key channels used in aerosol retrievals between MODIS and VIIRS mean that significant effort is required to revise aerosol models and surface reflectance determination modules previously developed using MODIS data. In this study, we will show the global (land and ocean) distribution of aerosols from Version 1 of the VIIRS Deep Blue data set. The preliminary validation results of these new VIIRS Deep Blue aerosol products using data from AERONET sunphotometers over land and ocean will be discussed. We will also compare the monthly averaged Deep Blue aerosol optical thickness (AOT) from VIIRS with the MODIS C6 products to investigate if any systematic biases may exist between MODIS C6 and VIIRS AOT.

  14. Episodes of intensified biological productivity in the subtropical Atlantic Ocean during the termination of the Middle Eocene Climatic Optimum (MECO)

    NASA Astrophysics Data System (ADS)

    Moebius, Iris; Friedrich, Oliver; Edgar, Kirsty M.; Sexton, Philip F.

    2015-08-01

    The Middle Eocene Climatic Optimum (MECO) is an ~500 kyr interval of pronounced global warming from which the climate system recovered in <50 kyr. The deep-sea sedimentary record can provide valuable insight on the marine ecosystem response to this protracted global warming event and consequently on the ecological changes during this time. Here we present new benthic foraminiferal assemblage data from Ocean Drilling Program Site 1051 in the subtropical North Atlantic, spanning the MECO and post-MECO interval (41.1 to 39.5 Ma). We find little change in the species composition of benthic foraminiferal assemblages during the studied interval, suggesting that the rate of environmental change was gradual enough that these organisms were able to adapt. However, we identify two transient intervals associated with peak warming (higher-productivity interval (HPI)-1; 40.07-39.96 Ma) and shortly after the MECO (HPI-2; 39.68-39.55 Ma), where benthic foraminiferal accumulation rates increase by an order of magnitude. These HPIs at Site 1051 appear to coincide with intervals of strengthened productivity in the Tethys, Southern Ocean, and South Atlantic, and we suggest that an intensified hydrological cycle during the climatic warmth of the MECO was responsible for eutrophication of marine shelf and slope environments.

  15. A Comparison of Latent Heat Fluxes over Global Oceans for Four Flux Products

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.

    2003-01-01

    To improve our understanding of global energy and water cycle variability, and to improve model simulations of climate variations, it is vital to have accurate latent heat fluxes (LHF) over global oceans. Monthly LHF, 10-m wind speed (U10m), 10-m specific humidity (Q10h), and sea-air humidity difference (Qs-Q10m) of GSSTF2 (version 2 Goddard Satellite-based Surface Turbulent Fluxes) over global Oceans during 1992-93 are compared with those of HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP (NCEP/NCAR reanalysis). The mean differences, standard deviations of differences, and temporal correlation of these monthly variables over global Oceans during 1992-93 between GSSTF2 and each of the three datasets are analyzed. The large-scale patterns of the 2yr-mean fields for these variables are similar among these four datasets, but significant quantitative differences are found. The temporal correlation is higher in the northern extratropics than in the south for all variables, with the contrast being especially large for da Silva as a result of more missing ship data in the south. The da Silva has extremely low temporal correlation and large differences with GSSTF2 for all variables in the southern extratropics, indicating that da Silva hardly produces a realistic variability in these variables. The NCEP has extremely low temporal correlation (0.27) and large spatial variations of differences with GSSTF2 for Qs-Q10m in the tropics, which causes the low correlation for LHF. Over the tropics, the HOAPS LHF is significantly smaller than GSSTF2 by approx. 31% (37 W/sq m), whereas the other two datasets are comparable to GSSTF2. This is because the HOAPS has systematically smaller LHF than GSSTF2 in space, while the other two datasets have very large spatial variations of large positive and negative LHF differences with GSSTF2 to cancel and to produce smaller regional-mean differences. Our analyses suggest that the GSSTF2 latent heat flux

  16. How do strategic decisions and operative practices affect operating room productivity?

    PubMed

    Peltokorpi, Antti

    2011-12-01

    Surgical operating rooms are cost-intensive parts of health service production. Managing operating units efficiently is essential when hospitals and healthcare systems aim to maximize health outcomes with limited resources. Previous research about operating room management has focused on studying the effect of management practices and decisions on efficiency by utilizing mainly modeling approach or before-after analysis in single hospital case. The purpose of this research is to analyze the synergic effect of strategic decisions and operative management practices on operating room productivity and to use a multiple case study method enabling statistical hypothesis testing with empirical data. 11 hypotheses that propose connections between the use of strategic and operative practices and productivity were tested in a multi-hospital study that included 26 units. The results indicate that operative practices, such as personnel management, case scheduling and performance measurement, affect productivity more remarkably than do strategic decisions that relate to, e.g., units' size, scope or academic status. Units with different strategic positions should apply different operative practices: Focused hospital units benefit most from sophisticated case scheduling and parallel processing whereas central and ambulatory units should apply flexible working hours, incentives and multi-skilled personnel. Operating units should be more active in applying management practices which are adequate for their strategic orientation.

  17. Factors Affecting Pheromone Production by the Pepper Weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and Collection Efficiency

    PubMed Central

    Eller, Fred J.; Palmquist, Debra E.

    2014-01-01

    Several factors affecting pheromone production by male pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae) as well as collection efficiency were investigated. Factors studied included: porous polymer adsorbents (Tenax versus Super Q), male age, time of day, male density, and male diet. Super Q was found to be a superior adsorbent for the male-produced alcohols and geranic acid as well as the plant-produced E-β-ocimene. Pheromone production increased with male age up to about age 15 days old and then tapered off. Male pepper weevils produced the highest amount of pheromone between noon and 2 pm (i.e., 4 to 6 h after “lights on”) and were producing ca. 800 ng/h during this period. Thereafter, pheromone production decreased and was extremely low during the scotophase (i.e., ca. 12 ng/h). Male pepper weevil density had a significant effect on both release rate and pheromone composition. Pheromone production on a per male basis was highest for individual males and the percentage of geranic acid in the blend was lowest for individual males. Male pepper weevils produced only extremely low amounts of pheromone when feeding on artificial diet; however, they produced very high amounts when on fresh peppers. Together, this information will be useful in designing better attractant lures for pepper weevils. PMID:26462948

  18. Factors Affecting Pheromone Production by the Pepper Weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and Collection Efficiency.

    PubMed

    Eller, Fred J; Palmquist, Debra E

    2014-11-18

    Several factors affecting pheromone production by male pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae) as well as collection efficiency were investigated. Factors studied included: porous polymer adsorbents (Tenax versus Super Q), male age, time of day, male density, and male diet. Super Q was found to be a superior adsorbent for the male-produced alcohols and geranic acid as well as the plant-produced E-β-ocimene. Pheromone production increased with male age up to about age 15 days old and then tapered off. Male pepper weevils produced the highest amount of pheromone between noon and 2 pm (i.e., 4 to 6 h after "lights on") and were producing ca. 800 ng/h during this period. Thereafter, pheromone production decreased and was extremely low during the scotophase (i.e., ca. 12 ng/h). Male pepper weevil density had a significant effect on both release rate and pheromone composition. Pheromone production on a per male basis was highest for individual males and the percentage of geranic acid in the blend was lowest for individual males. Male pepper weevils produced only extremely low amounts of pheromone when feeding on artificial diet; however, they produced very high amounts when on fresh peppers. Together, this information will be useful in designing better attractant lures for pepper weevils.

  19. Evolution and Production of Calcareous Nannoplankton During the Cretaceous as Proxies of LIP-induced Oceanic Fertilization, Acidification and Anoxia

    NASA Astrophysics Data System (ADS)

    Erba, E.; Bottini, C.; Tiraboschi, D.

    2008-12-01

    Through the Phanerozoic, biota have been intimately linked to Earth's degassing inducing major changes in composition and structure of the ocean-atmosphere system. Emplacement of large igneous provinces (LIPs) has been the primary natural source of atmCO2 with dramatic consequences on climate and ecosystems. During the mid-Cretaceous the Ontong Java-Manihiki and Caribbean Plateaus LIPs are recognized as responsible of pCO2 as high as 2000 ppm. Coeval biocalcification crises occurred in pelagic and neritic settings, suggesting a causal link between high concentrations of carbon dioxide and drops in benthic and planktonic calcifiers' efficiency. Within the oceanic biosphere, calcareous nannoplankton play a key-role as: (1) is widespread and consists of cosmopolitan and endemic taxa; (2) has a 220 My-long evolutionary history; (3) is one the most effective calcite producers; (4) is relevant for the C cycle; (5) is extremely sensitive to environmental variations. Diversity pulses of Cretaceous calcareous nannoplankton are grossly coeval with LIP construction, climate and sea-level changes, variations in ocean structure and composition, suggesting that evolutionary patterns are closely linked to environmental modifications. We explored time-intervals of LIP formation marked by nannoplankton adaptation/evolution, quantifying evolutionary rates, species richness, abundance, calcite production and morphometry. High-resolution investigations of the initial phase of both early Aptian oceanic anoxic event (OAE) 1a and latest Cenomanian OAE 2 pointed out major evolutionary changes, decreases in heavily calcified nannoliths and occurrence of dwarf coccoliths. Nannoplankton calcification crises and dwarfism is here interpreted as forced by rapidly increasing pCO2 during formation of the Ontong Java-Maniniki and Caribbean Plateaus. Alternatively or concurrently, calcification crash and dwarfism might result from enhanced fertility associated to OAE1a and OAE2 regardless of ocean

  20. The main issues affecting coasts of the Indian and western Pacific Oceans: a meta-analysis from Seas at the Millennium.

    PubMed

    Sheppard, C

    2001-12-01

    A review of the world oceans in three volumes by 365 scientists, provides scope for several 'meta-analyses' of the main problems affecting over 100 areas in the year 2000. This article summarises the main issues affecting a sub-set of the reviewed areas, covering Asian, African and Arabian countries dealt with in Volume 2, which included over 50 articles. From all issues raised, assessment is made of the nature of the major ones, including evaluation of reasons why so many of them remain important issues after so much attention to them. These include long standing problems, several problems more newly flagged as becoming particularly important, the issue of global warming and no less than three related issues connected with fishing and over exploitation. One or two issues such as industrial pollution and sewage, previously considered of almost universal concern, almost traditional pollution issues even, continue to feature strongly for some countries, but while these were almost always referred to in Seas chapters, by and large these categories appear not to be the most pressing of issues today, except in localized areas (albeit areas where huge numbers of people live). Perhaps other issues have simply taken over. They are excluded from this article.

  1. Constraints on the sources of branched GDGTs in open ocean sediments: dust transport or in situ production?

    NASA Astrophysics Data System (ADS)

    Weijers, J.; Schefuss, E.; Kim, J.; Sinninghe Damsté, J. S.; Schouten, S.

    2012-12-01

    Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are membrane lipids synthesized by soil bacteria that, upon soil erosion, are transported by rivers to the ocean where they accumulate in the near shore sedimentary archive. The degrees of cyclisation (CBT) and methylation (MBT) of these compounds have been shown to relate to soil pH and annual mean air temperature [1]. Therefore, brGDGTs in near shore sedimentary archives can be used to estimate past continental air temperatures and enable a direct comparison of these to marine sea surface temperature estimates obtained from the same samples. In addition, brGDGT abundance relative to crenarchaeol, an isoprenoid GDGT synthesized by marine pelagic Thaumarchaeota, quantified in the branched vs. isoprenoid tetraether (BIT) index, is an indicator of the relative input of soil organic matter in near shore sediments [2]. High BIT values near river outflows testify of relative strong soil organic matter input and generally the BIT index will decrease off shore to values near 0, the marine end-member value. Even in remote open ocean sediments, however, the BIT index will rarely reach 0 as small amounts of brGDGTs are often present. The occurrence of these brGDGTs in open marine settings might be a result of i) dust input, ii) sediment dispersion from near coastal areas, or iii) in situ production in marine sediments. In order to constrain the origin of branched GDGTs in open marine sediments we analyzed i) atmospheric dust samples taken along an equatorial African coastal transect, ii) marine surface waters near and away of the Congo river outflow, iii) a series of surface sediments at and around the Congo deep sea fan, and iv) a series of open marine surface sediments from different oceans with BIT values < 0.08. Our results show that brGDGTs are present, though in relative low amounts, in dust. Their distribution resembles that of soil input as also found in the Congo deep sea fan, with MBT and CBT values that

  2. Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Hamme, Roberta C.; Cassar, Nicolas; Lance, Veronica P.; Vaillancourt, Robert D.; Bender, Michael L.; Strutton, Peter G.; Moore, Tommy S.; Degrandpre, Michael D.; Sabine, Christopher L.; Ho, David T.; Hargreaves, Bruce R.

    2012-04-01

    We use continuous and discrete measurements of the dissolved O2/Ar ratio in the mixed layer to investigate the dynamics of biological productivity during the Southern Ocean Gas Exchange Experiment in March and April 2008. Injections of SF6 defined two water masses (patches) that were followed for up to 2 weeks. In the first patch, dissolved O2/Ar was supersaturated, indicating net biological production of organic carbon. In the second patch, rapidly decreasing O2/Ar could only be reasonably explained if the mixed layer was experiencing a period of net heterotrophy. The observations rule out dominant contributions from vertical mixing, lateral dilution, or respiration in the ship's underway seawater supply lines. We also compare nine different estimates of net community, new, primary, or gross production made during the experiment. Net community and new production estimates agreed well in the first patch but disagreed in the second patch, both during an initial net heterotrophic period but also during the apparently autotrophic period at the end of the observations. Rapidly changing productivity during the second patch complicated the comparison of methods that integrate over daily and several week timescales. Primary productivity values from on-deck 24 h 14C incubations and gross carbon production values from photosynthesis-irradiance experiments were nearly identical even during highly dynamic periods of net heterotrophy, while gross oxygen production measurements were 3.5-4.2 times higher but with uncertainties in that ratio near ±2. These comparisons show that the photosynthesis-irradiance experiments based on 1-2 h 14C incubations underestimated gross carbon production.

  3. Soil water repellency affects production and transport of CO2 and CH4 in soil

    NASA Astrophysics Data System (ADS)

    Urbanek, Emilia; Qassem, Khalid

    2016-04-01

    Soil moisture is known to be vital in controlling both the production and transport of C gases in soil. Water availability regulates the decomposition rates of soil organic matter by the microorganisms, while the proportion of water/air filled pores controls the transport of gases within the soil and at the soil-atmosphere interface. Many experimental studies and process models looking at soil C gas fluxes assume that soil water is uniformly distributed and soil is easily wettable. Most soils, however, exhibit some degree of soil water repellency (i.e. hydrophobicity) and do not wet spontaneously when dry or moderately moist. They have restricted infiltration and conductivity of water, which also results in extremely heterogeneous soil water distribution. This is a world-wide occurring phenomenon which is particularly common under permanent vegetation e.g. forest, grass and shrub vegetation. This study investigates the effect of soil water repellency on microbial respiration, CO2 transport within the soil and C gas fluxes between the soil and the atmosphere. The results from the field monitoring and laboratory experiments show that soil water repellency results in non-uniform water distribution in the soil which affects the CO2 and CH4 gas fluxes. The main conclusion from the study is that water repellency not only affects the water relations in the soil, but has also a great impact on greenhouse gas production and transport and therefore should be included as an important parameter during the sites monitoring and modelling of gas fluxes.

  4. Electrostatics in the environment: How they may affect health and productivity

    NASA Astrophysics Data System (ADS)

    Jamieson, K. S.; Simon, H. M. Ap; Bell, J. N. B.

    2008-12-01

    Lifestyles and the built environment have changed considerably during the past century and have greatly influenced the electric field, small air ion and charged submicron aerosol regimes to which individuals are often exposed. In particular the use of electrical items, synthetic materials/finishes and low humidity levels that can lead to the generation of high electrostatic charges, along with inadequate grounding protocols and building techniques which create 'Faraday cage'-like conditions, have all greatly altered the electromagnetic nature of the microclimates many people occupy for prolonged periods of time. It is suggested that the type, polarity and strengths of electric fields individuals are exposed to may affect their likelihood of succumbing to ill-health through influencing biological functioning, oxygen-uptake and retention rates of inhaled submicron contaminants to a far greater degree than previously realised. These factors can also influence the degree of local surface contamination and adhesion that occurs. It is further suggested that both health and work productivity can be affected by such factors, and that improved 'best practice' electro-hygiene/productivity protocols should be adopted wherever practical.

  5. Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum.

    PubMed

    Subramaniam, Rajagopal; Narayanan, Swara; Walkowiak, Sean; Wang, Li; Joshi, Manisha; Rocheleau, Hélène; Ouellet, Thérèse; Harris, Linda J

    2015-11-01

    TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins [deoxynivalenol (DON)] and acetylated forms such as 15-Acetyl-DON) in the cereal pathogen Fusarium graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen-limiting conditions, sources of nitrogen and carbon, pH and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains underexplored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wild-type F. graminearum and a Δtri6 mutant strain, grown in nutrient-rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched-chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl-CoA-carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down-regulated TRI6 expression and reduced 15-ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15-ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum.

  6. TITER AND PRODUCT AFFECTS THE DISTRIBUTION OF GENE EXPRESSION AFTER INTRAPUTAMINAL CONVECTION-ENHANCED DELIVERY

    PubMed Central

    Emborg, Marina E.; Hurley, Samuel A.; Joers, Valerie; Tromp, Do P.M.; Swanson, Christine R.; Ohshima-Hosoyama, Sachiko; Bondarenko, Viktorya; Cummisford, Kyle; Sonnemans, Marc; Hermening, Stephan; Blits, Bas; Alexander, Andrew L.

    2014-01-01

    Background Efficacy and safety of intracerebral gene therapy for brain disorders, like Parkinson’s disease, depends on appropriate distribution of gene expression. Objectives To assess if the distribution of gene expression is affected by vector titer and protein type. Methods Four adult macaque monkeys seronegative for adeno-associated virus 5 (AAV5) received in the right and left ventral postcommisural putamen 30μl inoculation of a high or low titer suspension of AAV5 encoding glial derived neurotrophic factor (GDNF) or green fluorescent protein (GFP). Inoculations were performed using convection enhanced delivery and intraoperative MRI (IMRI). Results IMRI confirmed targeting and infusion cloud irradiating from the catheter tip into surrounding area. Postmortem analysis six weeks after surgery revealed GFP and GDNF expression ipsilateral to the injection side that had a titer-dependent distribution. GFP and GDNF expression was also observed in fibers in the Substantia Nigra (SN) pars reticulata (pr), demonstrating anterograde transport. Few GFP-positive neurons were present in the SN pars compacta (pc), possibly by direct retrograde transport of the vector. GDNF was present in many SNpc and SNpr neurons. Conclusions After controlling for target and infusate volume, intracerebral distribution of gene product is affected by vector titer and product biology. PMID:24943657

  7. Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, Porolithon onkodes in an experimental system

    NASA Astrophysics Data System (ADS)

    Nash, M. C.; Uthicke, S.; Negri, A. P.; Cantin, N. E.

    2015-01-01

    There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesized that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement affected by increasing pCO2 levels (365, 444, 676 and 904 ppm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by pCO2. Our results show there was no significant effect of pCO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with pCO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.

  8. Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, Porolithon onkodes in an experimental system

    NASA Astrophysics Data System (ADS)

    Nash, M. C.; Uthicke, S.; Negri, A. P.; Cantin, N. E.

    2015-09-01

    There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesised that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes, the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement was affected by increasing CO2 levels (365, 444, 676 and 904 μatm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by CO2. Our results show that there was no significant effect of CO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with CO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.

  9. Effect of the salts of deep ocean water on the production of cordycepin and adenosine of Cordyceps militaris-fermented product.

    PubMed

    Hung, Yu-Ping; Wang, Jyh-Jye; Wei, Bai-Luh; Lee, Chun-Lin

    2015-12-01

    Cordyceps militaris is a type of entomogenous fungi and has been widely used as a medicinal fungus in Asia. Cordycepin produced by C. militaris has also been found to protect the liver. Moreover, deep ocean water (DOW) was proven to increase the functional compounds of functional fungi-fermented products. However, the regulation of the metals in DOW is still unclear