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Sample records for controls phytoplankton production

  1. Changing restoration rules: exotic bivalves interact with residence time and depth to control phytoplankton productivity

    Science.gov (United States)

    Lucas, Lisa V.; Thompson, Janet K.

    2012-01-01

    Non-native species are a prevalent ecosystem stressor that can interact with other stressors to confound resource management and restoration. We examine how interactions between physical habitat attributes and a particular category of non-native species (invasive bivalves) influence primary production in aquatic ecosystems. Using mathematical models, we show how intuitive relationships between phytoplankton productivity and controllable physical factors (water depth, hydraulic transport time) that hold in the absence of bivalves can be complicated—and even reversed—by rapid bivalve grazing. In light-limited environments without bivalves, shallow, hydrodynamically “slow” habitats should generally have greater phytoplankton biomass and productivity than deeper, “faster” habitats. But shallower, slower environments can be less productive than deeper, faster ones if benthic grazing is strong. Moreover, shallower and slower waters exhibit a particularly broad range of possible productivity outcomes that can depend on whether bivalves are present. Since it is difficult to predict the response of non-native bivalves to habitat restoration, outcomes for new shallow, slow environments can be highly uncertain. Habitat depth and transport time should therefore not be used as indicators of phytoplankton biomass and production where bivalve colonization is possible. This study provides for ecosystem management a particular example of a broad lesson: abiotic ecosystem stressors should be managed with explicit consideration of interactions with other major (including biotic) stressors. We discuss the applicability and management implications of our models and results for a range of aquatic system types, with a case study focused on the Sacramento-San Joaquin Delta (California, USA). Simple mathematical models like those used here can illuminate interactions between ecosystem stressors and provide process-based guidance for resource managers as they develop strategies

  2. Controls of primary production in two phytoplankton blooms in the Antarctic Circumpolar Current

    Science.gov (United States)

    Hoppe, C. J. M.; Klaas, C.; Ossebaar, S.; Soppa, M. A.; Cheah, W.; Laglera, L. M.; Santos-Echeandia, J.; Rost, B.; Wolf-Gladrow, D. A.; Bracher, A.; Hoppema, M.; Strass, V.; Trimborn, S.

    2017-04-01

    The Antarctic Circumpolar Current has a high potential for primary production and carbon sequestration through the biological pump. In the current study, two large-scale blooms observed in 2012 during a cruise with R.V. Polarstern were investigated with respect to phytoplankton standing stocks, primary productivity and nutrient budgets. While net primary productivity was similar in both blooms, chlorophyll a -specific photosynthesis was more efficient in the bloom closer to the island of South Georgia (39 °W, 50 °S) compared to the open ocean bloom further east (12 °W, 51 °S). We did not find evidence for light being the driver of bloom dynamics as chlorophyll standing stocks up to 165 mg m-2 developed despite mixed layers as deep as 90 m. Since the two bloom regions differ in their distance to shelf areas, potential sources of iron vary. Nutrient (nitrate, phosphate, silicate) deficits were similar in both areas despite different bloom ages, but their ratios indicated more pronounced iron limitation at 12 °W compared to 39 °W. While primarily the supply of iron and not the availability of light seemed to control onset and duration of the blooms, higher grazing pressure could have exerted a stronger control toward the declining phase of the blooms.

  3. Isoprene Production by Marine Phytoplankton

    Science.gov (United States)

    Shaw, S. L.; Chisholm, S. W.; Prinn, R. G.

    2001-12-01

    The oceans are a small source of non-methane hydrocarbons (NMHC). Previous work has established a photochemical source in the water column for many alkenes, and a phytoplanktonic source for isoprene. The focus of this work was to gain further insight on marine microbiological cycling of NMHC. A variety of phytoplankton species were examined for the ability to produce isoprene in laboratory cultures. All were found to have constant isoprene production rates per cell during exponential growth, with decreasing rates as the populations reached stationary phase. Production rates ranged from approximately 1x10-21 to 2x10-18 moles (cell)-1 (day)-1 for the different species. A positive allometric correlation between isoprene production rate and cell volume was found; highest production rates per cell were found for the largest cell tested, Emiliania huxleyi, and lowest rates for Prochlorococcus, the smallest. Isoprene production by Prochlorococcus was found to be a function of light intensity and temperature, with patterns similar to the relationships between growth rate of this species and these environmental parameters. Grazing (by Cafeteria roenbergensis) and cyanophage infection of Prochlorococcus both caused cell mortality, and thus the total amount of isoprene produced declined. While isoprene production per cell remained constant in the grazed cultures, there was a decrease in isoprene production per cell associated with the latent stage of cyanophage infection. We also regularly monitored 5 other NMHC, but detected no clear production or consumption of ethane, ethene, propene, 2-mepropene, or hexane from any of the phytoplankton or heterotrophic organisms tested. Total isoprene production in the water column was estimated for both oligotrophic and North Atlantic ocean regions using reported in situ measurements of cell abundance and our laboratory production rates. These estimates are on the order of 1 to 10 (x107 molecules isoprene (cm)-2 (sec)-1), which is

  4. Phytoplankton productivity quantified from chlorophyll fluorescence

    DEFF Research Database (Denmark)

    Hancke, Kasper; Dalsgaard, Tage; Sejr, Mikael Kristian

    Phytoplankton are the main food source for marine life, and accurate uantification of its productivity is essential for understanding how marine food webs function. As a novel non-invasive technology, chlorophyll fluorescence can be used to assess in situ primary production in phytoplankton...

  5. Phytoplankton diversity, biomass, and production

    Digital Repository Service at National Institute of Oceanography (India)

    Madondkar, S.G.P.; Gomes, H.; Parab, S.G.; Pednekar, S.; Goes, J.I.

    (September) phytoplankton counts range in Mandovi was 0.68 –1.36 X 10 sup(5) L sup(-1) and that of Zuari were 1.02 – 3.07 X 10 sup(5) L sup(-1). Similar pattern was also observed in pigment distribution. In Mandovi Chl a during non monsoon period was as high...

  6. Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)

    Science.gov (United States)

    Rochelle-Newall, E. J.; Chu, V. T.; Pringault, O.; Amouroux, D.; Arfi, R.; Bettarel, Y.; Bouvier, T.; Bouvier, C.; Got, P.; Nguyen, T. M. H.; Mari, X.; Navarro, P.; Duong, T. N.; Cao, T. T. T.; Pham, T. T.; Ouillon, S.; Torréton, J.-P.

    2011-01-01

    The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both

  7. Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam

    Directory of Open Access Journals (Sweden)

    E. J. Rochelle-Newall

    2011-01-01

    Full Text Available The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin were measured during two seasons: wet (July 2008 and dry (March 2009. Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also

  8. Development of phytoplankton communities: Implications of nutrient injections on phytoplankton composition, pH and ecosystem production

    DEFF Research Database (Denmark)

    Jakobsen, Hans; Blanda, Elisa; Stæhr, Peter Anton

    2015-01-01

    The development of a marine phytoplankton community was studied in a series of mesocosm tanks exposed to different levels of nutrient inputs. Key ecosystem variables such as phytoplankton species development, ecosystem net production (NEP), pH and bacteria production were measured. The overall ai...... ultimately uncoupling high bacterial production from primary production, leading to severe oxygen consumption following ephemeral blooms...

  9. Five Years of Experimental Warming Increases the Biodiversity and Productivity of Phytoplankton.

    Science.gov (United States)

    Yvon-Durocher, Gabriel; Allen, Andrew P; Cellamare, Maria; Dossena, Matteo; Gaston, Kevin J; Leitao, Maria; Montoya, José M; Reuman, Daniel C; Woodward, Guy; Trimmer, Mark

    2015-12-01

    Phytoplankton are key components of aquatic ecosystems, fixing CO2 from the atmosphere through photosynthesis and supporting secondary production, yet relatively little is known about how future global warming might alter their biodiversity and associated ecosystem functioning. Here, we explore how the structure, function, and biodiversity of a planktonic metacommunity was altered after five years of experimental warming. Our outdoor mesocosm experiment was open to natural dispersal from the regional species pool, allowing us to explore the effects of experimental warming in the context of metacommunity dynamics. Warming of 4°C led to a 67% increase in the species richness of the phytoplankton, more evenly-distributed abundance, and higher rates of gross primary productivity. Warming elevated productivity indirectly, by increasing the biodiversity and biomass of the local phytoplankton communities. Warming also systematically shifted the taxonomic and functional trait composition of the phytoplankton, favoring large, colonial, inedible phytoplankton taxa, suggesting stronger top-down control, mediated by zooplankton grazing played an important role. Overall, our findings suggest that temperature can modulate species coexistence, and through such mechanisms, global warming could, in some cases, increase the species richness and productivity of phytoplankton communities.

  10. EXAMINATION OF SILICATE LIMITATION OF PRIMARY PRODUCTION IN JIAOZHOU BAY, CHINA Ⅰ. SILICATE BEING A LIMITING FACTOR OF PHYTOPLANKTON PRIMARY PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    杨东方; 张经; 吕吉斌; 高振会; 陈豫

    2002-01-01

    Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou B ay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO-3-N, NO-2-N, NH+4-N, SiO2-3-Si, PO3-4-P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq.(1) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temp erature; that the main factor controlling the primary production is Si; that water temper ature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecologica l niches for C, the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D, the coefficient of water temperature's effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay , the biogeochemical sediment process of the silicon, the phytoplankton predominan t species and the phytoplankton structure. The authors considered silicate a limit ing factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and up take by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrins ic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant

  11. EXAMINATION OF SILICATE LIMITATION OF PRIMARY PRODUCTION IN JIAOZHOU BAY, CHINA——I. SILICATE BEING A LIMITING FACTOR OF PHYTOPLANKTON PRIMARY PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    杨东方; 张经; 吕吉斌; 高振会; 陈豫

    2002-01-01

    Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou Bay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO3--N, NO2--N, NH4+-N, SIO32--Si, PO43--P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq. ( 1 ) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temperature; that the main factor controlling the primary production is Si; that water temperature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecological niches for C, the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D, the coefficient of water temperature's effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay, the biogeochemical sediment process of the silicon, the phytoplankton predominant species and the phytoplankton structure. The authors considered silicate a limiting factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and uptake by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrinsic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant

  12. Resource supply overrides temperature as a controlling factor of marine phytoplankton growth.

    Science.gov (United States)

    Marañón, Emilio; Cermeño, Pedro; Huete-Ortega, María; López-Sandoval, Daffne C; Mouriño-Carballido, Beatriz; Rodríguez-Ramos, Tamara

    2014-01-01

    The universal temperature dependence of metabolic rates has been used to predict how ocean biology will respond to ocean warming. Determining the temperature sensitivity of phytoplankton metabolism and growth is of special importance because this group of organisms is responsible for nearly half of global primary production, sustains most marine food webs, and contributes to regulate the exchange of CO2 between the ocean and the atmosphere. Phytoplankton growth rates increase with temperature under optimal growth conditions in the laboratory, but it is unclear whether the same degree of temperature dependence exists in nature, where resources are often limiting. Here we use concurrent measurements of phytoplankton biomass and carbon fixation rates in polar, temperate and tropical regions to determine the role of temperature and resource supply in controlling the large-scale variability of in situ metabolic rates. We identify a biogeographic pattern in phytoplankton metabolic rates, which increase from the oligotrophic subtropical gyres to temperate regions and then coastal waters. Variability in phytoplankton growth is driven by changes in resource supply and appears to be independent of seawater temperature. The lack of temperature sensitivity of realized phytoplankton growth is consistent with the limited applicability of Arrhenius enzymatic kinetics when substrate concentrations are low. Our results suggest that, due to widespread resource limitation in the ocean, the direct effect of sea surface warming upon phytoplankton growth and productivity may be smaller than anticipated.

  13. Resource supply overrides temperature as a controlling factor of marine phytoplankton growth.

    Directory of Open Access Journals (Sweden)

    Emilio Marañón

    Full Text Available The universal temperature dependence of metabolic rates has been used to predict how ocean biology will respond to ocean warming. Determining the temperature sensitivity of phytoplankton metabolism and growth is of special importance because this group of organisms is responsible for nearly half of global primary production, sustains most marine food webs, and contributes to regulate the exchange of CO2 between the ocean and the atmosphere. Phytoplankton growth rates increase with temperature under optimal growth conditions in the laboratory, but it is unclear whether the same degree of temperature dependence exists in nature, where resources are often limiting. Here we use concurrent measurements of phytoplankton biomass and carbon fixation rates in polar, temperate and tropical regions to determine the role of temperature and resource supply in controlling the large-scale variability of in situ metabolic rates. We identify a biogeographic pattern in phytoplankton metabolic rates, which increase from the oligotrophic subtropical gyres to temperate regions and then coastal waters. Variability in phytoplankton growth is driven by changes in resource supply and appears to be independent of seawater temperature. The lack of temperature sensitivity of realized phytoplankton growth is consistent with the limited applicability of Arrhenius enzymatic kinetics when substrate concentrations are low. Our results suggest that, due to widespread resource limitation in the ocean, the direct effect of sea surface warming upon phytoplankton growth and productivity may be smaller than anticipated.

  14. Do high concentrations of microcystin prevent Daphnia control of phytoplankton?

    Science.gov (United States)

    Chislock, Michael F; Sarnelle, Orlando; Jernigan, Lauren M; Wilson, Alan E

    2013-04-15

    Toxin-producing cyanobacteria have frequently been hypothesized to limit the ability of herbivorous zooplankton (such as Daphnia) to control phytoplankton biomass by inhibiting feeding, and in extreme cases, causing zooplankton mortality. Using limnocorral experiments in hyper-eutrophic ponds located in Alabama and Michigan (U.S.A.), we tested the hypothesis that high levels of cyanobacteria and microcystin, a class of hepatotoxins produced by several cyanobacterial genera, prevent Daphnia from strongly reducing phytoplankton abundance. At the start of the first experiment (Michigan), phytoplankton communities were dominated by toxic Microcystis and Anabaena (∼96% of total phytoplankton biomass), and concentrations of microcystin were ∼3 μg L⁻¹. Two weeks after adding Daphnia pulicaria from a nearby eutrophic lake, microcystin levels increased to ∼6.5 μg L⁻¹, yet Daphnia populations increased exponentially (r = 0.24 day⁻¹). By the third week, Daphnia had suppressed phytoplankton biomass by ∼74% relative to the no Daphnia controls and maintained reduced phytoplankton biomass until the conclusion of the five-week experiment. In the second experiment (Alabama), microcystin concentrations were greater than 100 μg L⁻¹, yet a mixture of three D. pulicaria clones from eutrophic lakes in southern MI increased and again reduced phytoplankton biomass, in this case by over 80%. The ability of Daphnia to increase in abundance and suppress phytoplankton biomass, despite high initial levels of cyanobacteria and microcystin, indicates that the latter does not prevent strong control of phytoplankton biomass by Daphnia genotypes that are adapted to environments with abundant cyanobacteria and associated cyanotoxins.

  15. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton.

    Science.gov (United States)

    Mincer, Tracy J; Aicher, Athena C

    2016-01-01

    Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.

  16. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Tracy J Mincer

    Full Text Available Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus, and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.

  17. Phytoplankton productivity in newly dug fish ponds within Lake ...

    African Journals Online (AJOL)

    EJIRO

    Key words: phytoplankton, primary productivity, fish ponds, light-limitation, Uganda. ... options for poor farmers and increase their income while reducing their vulnerability and also improving land and water management (Briones et al., 2004). However much ... was estimated using chlorophyll-a method (Wetzel and Likens,.

  18. Phytoplankton biomass, production and potential export in the North Water

    Science.gov (United States)

    Klein, Bert; LeBlanc, Bernard; Mei, Zhi-Ping; Beret, Rachel; Michaud, Josée; Mundy, C.-J.; von Quillfeldt, Cecilie H.; Garneau, Marie-Ève; Roy, Suzanne; Gratton, Yves; Cochran, J. Kirk; Bélanger, Simon; Larouche, Pierre; Pakulski, J. Dean; Rivkin, Richard B.; Legendre, Louis

    The seasonal patterns of phytoplankton biomass and production were determined in the North Water, located between Greenland and Ellesmere Island (Canadian Arctic), in August 1997, April-July 1998, and August-September 1999. The patterns differed among the four defined regions of this large polynya, i.e. North (>77.5°N), East (>75°W), West (5 μm) fraction dominated the biomass and production during the bloom. During July, August, and September, biomass and production decreased over the whole region, with the highest biomass, dominated by large cells, occurring in the North. The annual particulate and dissolved phytoplankton production were the highest ever reported for the high Arctic, reaching maximum values of 254 and 123 g C m -2 yr -1, respectively, in the East. Rates in the North and West were considerably lower than in the East (ca. two- and three-fold, respectively). The f-ratios (i.e. ratio of new to total production), derived from the size structure of phytoplankton, were high north of 76°N (0.4-0.7). Regionally, this indicated a high potential export of particulate organic carbon ( EPOC) from the phytoplankton community to other trophic compartments and/or downwards in the East (155 g C m -2 yr -1), with lower values in the North and West (i.e. 77 and 42 g C m -2 yr -1, respectively). The seasonal and spatial patterns of EPOC were consistent with independent estimates of potential carbon export. Phytoplankton biomass and production were generally dominated by the large size fraction, whereas EPOC seemed to be dominated by the large size fraction early in the season and by the small size fraction (<5 μm) from June until the end of the growing season.

  19. Interannual Variation in Phytoplankton Primary Production at A Global Scale

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    Cecile S. Rousseaux

    2013-12-01

    Full Text Available We used the NASA Ocean Biogeochemical Model (NOBM combined with remote sensing data via assimilation to evaluate the contribution of four phytoplankton groups to the total primary production. First, we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998–2011. Globally, diatoms contributed the most to the total phytoplankton production (~50%, the equivalent of ~20 PgC∙y−1. Coccolithophores and chlorophytes each contributed ~20% (~7 PgC∙y−1 of the total primary production and cyanobacteria represented about 10% (~4 PgC∙y−1 of the total primary production. Primary production by diatoms was highest in the high latitudes (>40° and in major upwelling systems (Equatorial Pacific and Benguela system. We then assessed interannual variability of this group-specific primary production over the period 1998–2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4% (1–2 PgC∙y−1. We assessed the effects of climate variability on group-specific primary production using global (i.e., Multivariate El Niño Index, MEI and “regional” climate indices (e.g., Southern Annular Mode (SAM, Pacific Decadal Oscillation (PDO and North Atlantic Oscillation (NAO. Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p < 0.05 between the MEI and the group-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatoms/cyanobacteria and in the North Atlantic (chlorophytes and coccolithophores. We found that climate variability as indicated by SAM had only a limited effect on group-specific primary production in the Southern Ocean. These

  20. Assessing controls on cross-shelf phytoplankton and suspended particle distributions using repeated bio-optical glider surveys

    Science.gov (United States)

    Henderikx Freitas, Fernanda; Siegel, David A.; Washburn, Libe; Halewood, Stuart; Stassinos, Erik

    2016-10-01

    Characterizing the space/time variability of bio-optical properties is essential to understand the mechanisms that control cross-shelf phytoplankton and suspended particle distributions in coastal waters. Approximately 400 high-resolution cross-shelf sections of bio-optical properties collected with an oceanographic glider in the coastal Santa Barbara Channel, California, revealed complex relationships among optical properties and environmental conditions. Surface waves were found as a proximate control on suspended sediment variability for both inner and midshelves. Increases in phytoplankton abundances attributed to horizontal advection and upwelling events were observed only on episodic time scales. The lack of all-encompassing linear relationships between environmental forcings and changes in cross-shelf phytoplankton highlights the challenge of decoupling bio-optical signals from their controlling processes in coastal zones where phytoplankton distributions are patchy, and where nearshore and offshore phytoplankton populations and suspended sediments often occupy the same portion of the water column. Clear relationships between runoff and productivity were not observed. Temporal variability of suspended particles and phytoplankton distributions were roughly independent from each other during stratified conditions. Synchronous increases in phytoplankton and suspended sediments were observed when associated with strong upwelling events that may induce mixing and promote productivity. The repeated glider sections illustrated many processes regulating phytoplankton and particle transport in the innershelf and showed the difficulty in establishing general connections between high-frequency changes in optical properties and potential environmental forcings in a complex coastal environment.

  1. Modelling the production of dimethylsulfide during a phytoplankton bloom

    Science.gov (United States)

    Gabric, Albert; Murray, Nicholas; Stone, Lewi; Kohl, Manfred

    1993-12-01

    Dimethylsulfide (DMS) is an important sulfur-containing atmospheric trace gas of marine biogenic origin. DMS emitted from the oceans may be a precursor of tropospheric aerosols and cloud condensation nuclei (CCN), thereby affecting the Earth's radiative balance and possibly constituting a negative feedback to global warming, although this hypothesis is still somewhat controversial. The revised conceptual model of the marine pelagic food web gives a central role to planktonic bacteria. Recent experiments have shown that consumption of dissolved DMS by microbial metabolism may be more important than atmospheric exchange in controlling its concentration in surface waters and hence its ventilation to the atmosphere. In this paper we investigate the effect of the marine food web on cycling of dissolved DMS in surface waters during a phytoplankton bloom episode. A nitrogen-based flow network simulation model has been used to analyze the relative importance of the various biological and chemical processes involved. The model predictions suggest that the concentration of DMS in marine surface waters is indeed governed by bacterial metabolism. Environmental factors that affect the bacterial compartment are thus likely to have a relatively large influence on dissolved DMS concentrations. The ecological succession is particularly sensitive to the ratio of phytoplankton to bacterial nutrient uptake rates as well the interaction between herbivore food chain and the microbial loop. Importantly for the design of field studies, the model predicts that peak DMS concentrations are achieved during the decline of the phytoplankton bloom with a typical time lag between peak DMS and peak phytoplankton biomass of 1 to 2 days. Significantly, the model predicts a relatively high DMS concentration persisting after the phytoplankton bloom due to excretion from large protozoa and zooplankton, which may be an additional explanation for the lack of correlation between DMS and chlorophyll a

  2. Production of Biodiesel from Lipid of Phytoplankton Chaetoceros calcitrans through Ultrasonic Method

    OpenAIRE

    Raymond Kwangdinata; Indah Raya; Muhammad Zakir

    2014-01-01

    A research on production of biodiesel from lipid of phytoplankton Chaetoceros calcitrans through ultrasonic method has been done. In this research, we carried out a series of phytoplankton cultures to determine the optimum time of growth and biodiesel synthesis process from phytoplankton lipids. Process of biodiesel synthesis consists of two steps, that is, isolation of phytoplankton lipids and biodiesel synthesis from those lipids. Oil isolation process was carried out by ultrasonic extracti...

  3. Biodiversity increases the productivity and stability of phytoplankton communities.

    Directory of Open Access Journals (Sweden)

    Alina A Corcoran

    Full Text Available Global biodiversity losses provide an immediate impetus to elucidate the relationships between biodiversity, productivity and stability. In this study, we quantified the effects of species richness and species combination on the productivity and stability of phytoplankton communities subject to predation by a single rotifer species. We also tested one mechanism of the insurance hypothesis: whether large, slow-growing, potentially-defended cells would compensate for the loss of small, fast-growing, poorly-defended cells after predation. There were significant effects of species richness and species combination on the productivity, relative yield, and stability of phytoplankton cultures, but the relative importance of species richness and combination varied with the response variables. Species combination drove patterns of productivity, whereas species richness was more important for stability. Polycultures containing the most productive single species, Dunaliella, were consistently the most productive. Yet, the most species rich cultures were the most stable, having low temporal variability in measures of biomass. Polycultures recovered from short-term negative grazing effects, but this recovery was not due to the compensation of large, slow-growing cells for the loss of small, fast-growing cells. Instead, polyculture recovery was the result of reduced rotifer grazing rates and persisting small species within the polycultures. Therefore, although an insurance effect in polycultures was found, this effect was indirect and unrelated to grazing tolerance. We hypothesize that diverse phytoplankton assemblages interfered with efficient rotifer grazing and that this "interference effect" facilitated the recovery of the most productive species, Dunaliella. In summary, we demonstrate that both species composition and species richness are important in driving patterns of productivity and stability, respectively, and that stability in biodiverse

  4. Subsurface phytoplankton blooms fuel pelagic production in the North Sea

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering......, Limnol. Oceanogr., 12, 196-206, 1967)] occurring in these blooms may be greater than that occurring in the spring bloom in the same regions. Thus, such blooms may explain apparent discrepancies in production yields between different temperate marine systems...

  5. River Flow Control on the Phytoplankton Dynamics of Chesapeake Bay

    Institute of Scientific and Technical Information of China (English)

    YU Qingyun; WANG You; TANG Xuexi; LI Ming

    2013-01-01

    Recent observations support an emerging paradigm that climate variability dominates nutrient enrichment in costal ecosystems,which can explain seasonal and inter-annual variability of phytoplankton community composition,biomass (Chl-a),and primary production (PP).In this paper,we combined observation and modeling to investigate the regulation of phytoplankton dynamics in Chesapeake Bay.The year we chose is 1996 that has high river runoff and is usually called a ‘wet year’.A 3-D physical-biogeochemical model based on ROMS was developed to simulate the seasonal cycle and the regional distributions of phytoplankton biomass and primary production in Chesapeake Bay.Based on the model results,NO3 presents a strong contrast to the river nitrate load during spring and the highest concentration in the bay reaches around 80mmol N m3.Compared with the normal year,phytoplankton bloom in spring of 1996 appears in lower latitudes with a higher concentration.Quantitative comparison between the modeled and observed seasonal averaged dissolved inorganic nitrogen concentrations shows that the model produces reliable results.The correlation coefficient r2 for all quantities exceeds 0.95,and the skill parameter for the four seasons is all above 0.95.

  6. Production, Organic Characterization, and Phase Transformations of Marine Particles Aerosolized from a Laboratory Mesocosm Phytoplankton Bioreactor

    Science.gov (United States)

    Alpert, P. A.; Knopf, D. A.; Aller, J. Y.; Radway, J.; Kilthau, W.

    2012-12-01

    Previous studies have shown that particles emitted from bubble bursting and wave breaking of ocean waters with high biological activity can contain sea salts associated with organic material, with smaller particles containing a larger mass fraction of organics than larger particles. This likely indicates a link between phytoplankton productivity in oceans and particulate organic material in marine air. Once aerosolized, particles with significant amount of organic material can affect cloud activation and formation of ice crystals, among other atmospheric processes, thus influencing climate. This is significant for clouds and climate particularly over nutrient rich polar seas, in which concentrations of biological organisms can reach up to 109 cells per ml during spring phytoplankton blooms. Here we present results of bubble bursting aerosol production from a seawater mesocosm containing artificial seawater, natural seawater and unialgal cultures of three representative phytoplankton species. These phytoplankton (Thalassiosira pseudonana, Emilianaia huxleyi, and Nannochloris atomus), possessed siliceous frustules, calcareous frustules and no frustules, respectively. Bubbles were generated employing recirculating impinging water jets or glass frits. Dry and humidified aerosol size distributions and bulk aerosol organic composition were measured as a function of phytoplankton growth, and chlorophyll composition and particulate and dissolved organic carbon in the water were determined. Finally, particles were collected on substrates for ice nucleation and water uptake experiments, their elemental compositions were determined using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEMEDAX), and their carbon speciation was determined using scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Particle size distributions exposed to dry and humidified air employing

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

    Science.gov (United States)

    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

  8. Does nitrogen or silicon limit phytoplankton production in the Mississippi River plume and nearby regions?

    Science.gov (United States)

    Dortch, Quay; Whitledge, Terry E.

    1992-11-01

    The Mississippi River carries very high concentrations of nutrients into the otherwise oligotrophic Gulf of Mexico, resulting in high primary production and hypoxia along the Louisiana continental shelf. The hypothesis that nitrogen availability controls and ultimately limits phytoplankton production on the shelf was tested by measuring an indicator of nitrogen deficiency, the ratio of intracellular free amino acids/particulate protein (AA/Pr), in the area of the Mississippi River plume on a spring and a summer cruise. Neither AA/Pr ratios or nutrients in the water showed nitrogen limitation to be widespread. Ammonium concentrations were generally quite high, so the lack of phytoplankton nitrogen deficiency can be explained by rapid regeneration rates. Nitrogen limitation was most likely in the summer at high salinities. However, ratios of dissolved nutrient concentrations suggested that silicate was as likely, or sometimes more likely, to be a limiting nutrient than nitrogen. Although silicate depletion may not cause a decrease in productivity, it could result in major changes in phytoplankton size and species composition, and ultimately influence trophodynamics, regeneration, the fate of carbon, and severity and extent of hypoxia.

  9. Carbon disulphide production in laboratory cultures of marine phytoplankton

    Science.gov (United States)

    Xie, Huixiang; Scarratt, Michael G.; Moore, Robert M.

    Carbon disulphide (CS 2) data were collected from axenic monocultures of six species of marine phytoplankton. The tested species included Chaetoceros calcitrans, Phaeodactylum tricornutum, Phaeocystis sp., Porphyridium purpureum, Synechococcus sp. and Isochrysis sp. For a period of between two weeks and forty days, substantial accumulation of CS 2 was found in the cultures of C. calcitrans, P. tricornutum and Phaeocystis sp., whereas the change of CS 2 concentration in the remaining cultures was insignificant. C. calcitrans had a potential for CS 2 production about 10 times higher than P. tricornutum or Phaeocystis sp. The formation of the compound was strongly dependent on the physiological state of the cultured species. More investigation is needed to elucidate the mechanisms responsible for the formation of this sulphur compound in these cultures.

  10. Small phytoplankton contribution to the standing stocks and the total primary production in the Amundsen Sea

    Science.gov (United States)

    Lee, Sang H.; Kim, Bo Kyung; Lim, Yu Jeong; Joo, HuiTae; Kang, Jae Joong; Lee, Dabin; Park, Jisoo; Ha, Sun-Yong; Lee, Sang Hoon

    2017-08-01

    Small phytoplankton are anticipated to be more important in a recently warming and freshening ocean condition. However, little information on the contribution of small phytoplankton to overall phytoplankton production is currently available in the Amundsen Sea. To determine the contributions of small phytoplankton to total biomass and primary production, carbon and nitrogen uptake rates of total and small phytoplankton were obtained from 12 productivity stations in the Amundsen Sea. The daily carbon uptake rates of total phytoplankton averaged in this study were 0.42 g C m-2 d-1 (SD = ± 0.30 g C m-2 d-1) and 0.84 g C m-2 d-1 (SD = ± 0.18 g C m-2 d-1) for non-polynya and polynya regions, respectively, whereas the daily total nitrogen (nitrate and ammonium) uptake rates were 0.12 g N m-2 d-1 (SD = ± 0.09 g N m-2 d-1) and 0.21 g N m-2 d-1 (SD = ± 0.11 g N m-2 d-1), respectively, for non-polynya and polynya regions, all of which were within the ranges reported previously. Small phytoplankton contributed 26.9 and 27.7 % to the total carbon and nitrogen uptake rates of phytoplankton in this study, respectively, which were relatively higher than the chlorophyll a contribution (19.4 %) of small phytoplankton. For a comparison of different regions, the contributions for chlorophyll a concentration and primary production of small phytoplankton averaged from all the non-polynya stations were 42.4 and 50.8 %, which were significantly higher than those (7.9 and 14.9 %, respectively) in the polynya region. A strong negative correlation (r2 = 0. 790, p<0. 05) was found between the contributions of small phytoplankton and the total daily primary production of phytoplankton in this study. This finding implies that daily primary production decreases as small phytoplankton contribution increases, which is mainly due to the lower carbon uptake rate of small phytoplankton than large phytoplankton.

  11. Small phytoplankton contribution to the total primary production in the highly productive Ulleung Basin in the East/Japan Sea

    Science.gov (United States)

    Joo, HuiTae; Son, SeungHyun; Park, Jung-Woo; Kang, Jae Joong; Jeong, Jin-Yong; Kwon, Jae-Il; Kang, Chang-Keun; Lee, Sang Heon

    2017-09-01

    The Ulleung Basin in the southwestern East/Japan Sea (hereafter East Sea) is known as a biologically productive ;hot spot; but climate-associated changes in the physicochemical oceanographic conditions and some biological changes have been reported. In this study, our main objective was to determine the contribution of small phytoplankton to the total primary production, which is valuable information for detecting marine ecosystem changes in the Ulleung Basin. The small phytoplankton productivity contributions determined by Moderate-Resolution Imaging Spectroradiometer (MODIS)-derived monthly productivities using a phytoplankton community-based productivity algorithm was significantly consistent with the field-measured productivity contributions of small phytoplankton in this study. The daily primary productivity of small phytoplankton ranged from 42.7 to 418.7 mg C m-2 d-1 with an average of 172.9 mg C m-2 d-1 (S.D. = ±61.4 mg C m-2 d-1, n = 120), and the annual contribution of small phytoplankton ranged from 19.6% to 28.4% with an average of 23.6% (S.D. = ±8.1%) in the Ulleung Basin from 2003 to 2012. Overall, large phytoplankton were a major contributor to the total primary production in the Ulleung Basin (76.4 ± 8.2%) from 2003 to 2012, which indicates that the Ulleung Basin is a highly productive region. A significantly negative relationship (p < 0.05) was found between the small phytoplankton primary productivity contribution and the annual primary production in this study. This finding revealed that the recent decreasing annual primary production in the Ulleung Basin could be a consequence of the increasing contribution of small phytoplankton. The response of phytoplankton to ongoing climate change depending on different-size phytoplankton compositions should be a subject for further investigation in the Ulleung Basin as a biologically highly productive region in the East Sea.

  12. Copepod grazing and their impact on phytoplankton standing stock and production in a tropical coastal water during the different seasons.

    Science.gov (United States)

    Jagadeesan, L; Jyothibabu, R; Arunpandi, N; Parthasarathi, S

    2017-03-01

    of the seasons, dominant calanoid copepods showed a negative selection of pico-phytoplankton fraction. The cyclopoid O. similis and Poecilostomatoid Corycaeus danae showed a positive selection of nano- and pico-phytoplankton fractions rather than micro-fraction. The grazing pressure of copepod community ingestion on micro-fraction was less (0.56% of the phytoplankton biomass and 1.06% of the phytoplankton production) during the PKSWM. This study provides, for the first time, clear findings on the seasonal variation in the top-down control of phytoplankton by copepods in a tropical coastal water ecosystem and discusses its implications on phytoplankton blooming, plankton food web, and biogeochemistry.

  13. Phytoplankton primary production in the world's estuarine-coastal ecosystems

    Science.gov (United States)

    Cloern, James E.; Foster, S.Q.; Kleckner, A.E.

    2014-01-01

    Estuaries are biogeochemical hot spots because they receive large inputs of nutrients and organic carbon from land and oceans to support high rates of metabolism and primary production. We synthesize published rates of annual phytoplankton primary production (APPP) in marine ecosystems influenced by connectivity to land – estuaries, bays, lagoons, fjords and inland seas. Review of the scientific literature produced a compilation of 1148 values of APPP derived from monthly incubation assays to measure carbon assimilation or oxygen production. The median value of median APPP measurements in 131 ecosystems is 185 and the mean is 252 g C m−2 yr−1, but the range is large: from −105 (net pelagic production in the Scheldt Estuary) to 1890 g C m−2 yr−1 (net phytoplankton production in Tamagawa Estuary). APPP varies up to 10-fold within ecosystems and 5-fold from year to year (but we only found eight APPP series longer than a decade so our knowledge of decadal-scale variability is limited). We use studies of individual places to build a conceptual model that integrates the mechanisms generating this large variability: nutrient supply, light limitation by turbidity, grazing by consumers, and physical processes (river inflow, ocean exchange, and inputs of heat, light and wind energy). We consider method as another source of variability because the compilation includes values derived from widely differing protocols. A simulation model shows that different methods reported in the literature can yield up to 3-fold variability depending on incubation protocols and methods for integrating measured rates over time and depth. Although attempts have been made to upscale measures of estuarine-coastal APPP, the empirical record is inadequate for yielding reliable global estimates. The record is deficient in three ways. First, it is highly biased by the large number of measurements made in northern Europe (particularly the Baltic region) and North America. Of the 1148

  14. Phytoplankton pigments and primary production around the oil fields off Maharashtra

    Digital Repository Service at National Institute of Oceanography (India)

    JiyalalRam, M.J.; Ramaiah, Neelam; Mehta, P.; Krishnakumari, L.; Nair, V.R.

    Studies on phytoplankton pigments, primary productivity and particulate organic carbon were made at 21 locations off Bombay (Maharashtra, India) and adjacent waters during the 48th cruise of @iORV Sagar Kanya@@ in December 1988 to January 1989...

  15. Seasonal patterns of phytoplankton biomass and productivity in a tropical estuarine complex (west coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Devassy, V.P.; Goes, J.I.

    Phytoplankton cell numbers and chlorophyll a determinations were made during the premonsoon, monsoon and postmonsoon periods in the Mandovi-Zuari estuarine complex (west coast of India). Primary productivity estimates agreed well with chlorophyll a...

  16. Effects of tidal shallowing and deepening on phytoplankton production dynamics: A modeling study

    Science.gov (United States)

    Lucas, L.V.; Cloern, J.E.

    2002-01-01

    Processes influencing estuarine phytoplankton growth occur over a range of time scales, but many conceptual and numerical models of estuarine phytoplankton production dynamics neglect mechanisms occurring on the shorter (e.g., intratidal) time scales. We used a numerical model to explore the influence of short time-scale variability in phytoplankton sources and sinks on long-term growth in an idealized water column that shallows and deepens with the semidiurnal tide. Model results show that tidal fluctuations in water surface elevation can determine whether long-term phytoplankton growth is positive or negative. Hourly-scale interactions influencing weekly-scale to monthly-scale phytoplankton dynamics include intensification of the depth-averaged benthic grazing effect by water column shallowing and enhancement of water column photosynthesis when solar noon coincides with low tide. Photosynthesis and benthic consumption may modulate over biweekly time scales due to spring-neap fluctuations in tidal range and the 15-d cycle of solar noon-low tide phasing. If tidal range is a large fraction of mean water depth, then tidal shallowing and deepening may significantly influence net phytoplankton growth. In such a case, models or estimates of long-term phytoplankton production dynamics that neglect water surface fluctuations may overestimate or underestimate net growth and could even predict the wrong sign associated with net growth rate.

  17. Interannual Variation in Phytoplankton Class-specific Primary Production at a Global Scale

    Science.gov (United States)

    Rousseaux, Cecile; Gregg, Watson

    2014-01-01

    Phytoplankton is responsible for over half of the net primary production on earth. The knowledge on the contribution of various phytoplankton groups to the total primary production is still poorly understood. Data from satellite observations suggest that for upwelling regions, photosynthetic rates by microplankton is higher than that of nanoplankton but that when the spatial extent is considered, the production by nanoplankton is comparable or even larger than microplankton. Here, we used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. Globally, diatoms were the group that contributed the most to the total phytoplankton production (approx. 50%) followed by coccolithophores and chlorophytes. Primary production by diatoms was highest in high latitude (>45 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nino Index, MEI) and 'regional' climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability. These results provide a modeling and data assimilation perspective to phytoplankton partitioning of primary production and contribute to our understanding of the dynamics of the carbon cycle in the oceans at a global scale.

  18. Production of biodiesel from lipid of phytoplankton Chaetoceros calcitrans through ultrasonic method.

    Science.gov (United States)

    Kwangdinata, Raymond; Raya, Indah; Zakir, Muhammad

    2014-01-01

    A research on production of biodiesel from lipid of phytoplankton Chaetoceros calcitrans through ultrasonic method has been done. In this research, we carried out a series of phytoplankton cultures to determine the optimum time of growth and biodiesel synthesis process from phytoplankton lipids. Process of biodiesel synthesis consists of two steps, that is, isolation of phytoplankton lipids and biodiesel synthesis from those lipids. Oil isolation process was carried out by ultrasonic extraction method using ethanol 96%, while biodiesel synthesis was carried out by transesterification reaction using methanol and KOH catalyst under sonication. Weight of biodiesel yield per biomass Chaetoceros calcitrans is 35.35%. Characterization of biodiesel was well carried out in terms of physical properties which are density and viscosity and chemical properties which are FFA content, saponification value, and iodine value. These values meet the American Society for Testing and Materials (ASTM D6751) standard levels, except for the viscosity value which was 1.14 g · cm(-3).

  19. Nutrients and toxin producing phytoplankton control algal blooms – a spatio-temporal study in a noisy environment

    Indian Academy of Sciences (India)

    Ram Rup Sarkar; Horst Malchow

    2005-12-01

    A phytoplankton-zooplankton prey-predator model has been investigated for temporal, spatial and spatio-temporal dissipative pattern formation in a deterministic and noisy environment, respectively. The overall carrying capacity for the phytoplankton population depends on the nutrient level. The role of nutrient concentrations and toxin producing phytoplankton for controlling the algal blooms has been discussed. The local analysis yields a number of stationary and/or oscillatory regimes and their combinations. Correspondingly interesting is the spatio-temporal behaviour, modelled by stochastic reaction-diffusion equations. The present study also reveals the fact that the rate of toxin production by toxin producing phytoplankton (TPP) plays an important role for controlling oscillations in the plankton system. We also observe that different mortality functions of zooplankton due to TPP have significant influence in controlling oscillations, coexistence, survival or extinction of the zooplankton population. External noise can enhance the survival and spread of zooplankton that would go extinct in the deterministic system due to a high rate of toxin production.

  20. Photochemical Production and Behavior of Hydroperoxyacids in Heterotrophic Bacteria Attached to Senescent Phytoplanktonic Cells

    Directory of Open Access Journals (Sweden)

    Frédéric Vaultier

    2013-06-01

    Full Text Available The photooxidation of cellular monounsaturated fatty acids was investigated in senescent phytoplanktonic cells (Emiliania huxleyi and in their attached bacteria under laboratory controlled conditions. Our results indicated that UV-visible irradiation of phytodetritus induced the photooxidation of oleic (produced by phytoplankton and bacteria and cis-vaccenic (specifically produced by bacteria acids. These experiments confirmed the involvement of a substantial singlet oxygen transfer from senescent phytoplanktonic cells to attached bacteria, and revealed a significant correlation between the concentration of chlorophyll, a photosensitizer, in the phytodetritus and the photodegradation state of bacteria. Hydroperoxyacids (fatty acid photoproducts appeared to be quickly degraded to ketoacids and hydroxyacids in bacteria and in phytoplanktonic cells. This degradation involves homolytic cleavage (most likely induced by UV and/or transition metal ions and peroxygenase activity (yielding epoxy acids.

  1. Silicon limitation on primary production and its destiny in Jiaozhou Bay, China Ⅵ: The ecological variation process of the phytoplankton

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The combination effect of light, water temperature and nutrients on phytoplankton growth in Jiaozhou Bay is studied in this paper. The order of importance of the influence on phytoplankton growth is determined as nutrients, water temperature, and light. The influence of these factors unveiled the mechanism of the influence, and revealed the variation process of the nutrients limiting phytoplankton primary production, and of the water temperature influencing the phytoplankton reproduction capacity, and hence influencing the structure of phytoplankton assemblage. Temporal and spatial quantification shows different stages of the influence by water temperature and nutrients on the phytoplankton growth. Moreover, the authors expatiated the ideal state of the phytoplankton growth and the reason of red tide occurrence. People should consider in their activity the input of nutrient Si first, and then the variation of water temperature, advocating sustainable development manner.

  2. Monitoring phytoplankton and marine biotoxins in production waters of the Netherlands: results after one decade

    NARCIS (Netherlands)

    Fels-Klerx, van der H.J.; Adamse, P.; Goedhart, P.W.; Poelman, M.; Pol-Hofstad, I.; Egmond, van H.J.; Gerssen, A.

    2012-01-01

    Shellfish products may be contaminated with marine biotoxins which, after consumption, may lead to human illness. The Netherlands has a regular monitoring programme for marine biotoxins and the possible toxic phytoplankton in shellfish production waters. The aim of the current study was to evaluate

  3. Productivity and abundance of bacteria and phytoplankton in Incheon Dock, western coast of Korea.

    Science.gov (United States)

    Yoo, Jong Su

    2008-07-01

    The monthly variations of abundance and productivity of bacteria and phytoplankton were investigated in 2002 at Incheon Dock in Korea, almost closed marine ecosystem. Incheon Dock has unique marine environment with scarcely a current and waves such as in a lake. The bacterial abundance was 0.4-6.3 x 10(6) cells x ml(-1), while the bacterial productivity showed in the range of 0.7-26.3 mgC m(-3) hr(-1). The phytoplankton chlorophyll-a concentrations fell between 2.1 and 18.1 microg x l(-1), where nanoplankton fractions contributed in 32.5-96.78% (average: 73.2%). The algal bloom occurred in March and August, and primary productivity measured by using 14C method, showed a fluctuation ranging from 49.4 to 4,359.4 mgC m(-2) day(-1). The primary productivity of nanotoplankton accounted for 79% of total phytoplankton. Meanwhile, the ratio of bacterial productivity over primary productivity was between 2.0 and 7.7. This study showed that the abundance and productivity of bacteria and phytoplankton were higher at Incheon Dock than those at other coastal areas in Korea. Especially the assimilation number was higher at Incheon Dock than that at lake Shihwa which is a severely eutrophicated area. This result indicates that Incheon Dock has unique ecosystem oceanographically and topographically and it differs from other coastal areas in terms of the low trophic level organisms being abundant and highly productive.

  4. Coastal phytoplankton productivity associated with different stability and nutrient patterns

    Science.gov (United States)

    Cabeçadas, G.; Brogueira, M. J.; Nogueira, M.; Cabeçadas, L.; Cavaco, H.; Nogueira, P.

    2003-04-01

    In order to assess the ecological status of the adjacent coastal zone of Tagus estuary (western Portugal) three cruises were carried out in 1994, 2000 and 2002. Coastal upwelling conditions prevailed during summer cruise (May/June 2002) and, also exceptionally, in winter (February/March 1994), and were absent in May 2000. The impact of such conditions on the chemical and biological properties of the coastal waters is examined. In March 1994, one week after the occurrence of upwelling favourable winds and under intense freshwater input from Tagus river (monthly mean 350 m^3/s), nutrient levels reached values up to 16.0 μmol/l NO_3, 1.0 μmol/l PO_4 and 14.0 μmol/l Si(OH)_4 in the estuarine plume, and an exceptional bloom of phytoplankton (chlorophyll \\underline{a} up to 40 mg/m^3) developed in the adjacent waters. In May/June 2002, during an upwelling event and when Tagus river inflow was reduced, nutrient levels did not surpass 9.0 μmol/l NO_3, 0.8 μmol/l PO_4 and 2.0 μmol/l Si(OH)_4, and phytoplankton biomass attained chlorophyll \\underline{a} levels of only 6 mg/m^3. By contrast, in May 2000 in a calm period and under moderate river discharge (190 m^3/s), nutrients reached values of NO_3 17.0 μmol/l, PO_4 1.0 μmol/l and Si(OH)_4 8.9 μmol/l and chlorophyll \\underline{a} exhibited values of 8.0 mg/m^3 in the Tagus estuarine plume. The results obtained in these different occasions point out to potential enhancement of phytoplankton growth when a shift on the upwelling pattern occurs in the region. Actually, in winter, the combined effect of maximum freshwater runoff and upwelling episodes is responsible for an extra supply of nutrients to the surface layers. Further, the intensification of the frontal boundary established between the river plume stratified water and the mixed upwelled water, is likely to promote the development of phytoplankton blooms over the coastal area.

  5. Are Methods for Estimating Primary Production and the Growth Rates of Phytoplankton Approaching Agreement?

    Science.gov (United States)

    Cullen, J. J.

    2016-02-01

    During the 1980s, estimates of primary productivity and the growth rates of phytoplankton in oligotrophic waters were controversial, in part because rates based on seasonal accumulations of oxygen in the shallow oxygen maximum were reported to be much higher than could be accounted for with measurements of photosynthesis based on incubations with C-14. Since then, much has changed: tested and standardized methods have been employed to collect comprehensive time-series observations of primary production and related oceanographic properties in oligotrophic waters of the North Pacific subtropical gyre and the Sargasso Sea; technical and theoretical advances have led to new tracer-based estimates of photosynthesis (e.g., oxygen/argon and triple isotopes of dissolved oxygen); and biogeochemical sensor systems on ocean gliders and profiling floats can describe with unprecedented resolution the dynamics of phytoplankton, oxygen and nitrate as driven by growth, loss processes including grazing, and vertical migration for nutrient acquisition. Meanwhile, the estimation of primary productivity, phytoplankton biomass and phytoplankton growth rates from remote sensing of ocean color has matured, complementing biogeochemical models that describe and predict these key properties of plankton dynamics. In a selective review focused on well-studied oligotrophic waters, I compare methods for estimating the primary productivity and growth rates of phytoplankton to see if they are converging on agreement, not only in the estimated rates, but also in the underlying assumptions, such as the ratio of gross- to net primary production — and how this relates to the measurement — and the ratio of chlorophyll to carbon in phytoplankton. Examples of agreement are encouraging, but some stark contrasts illustrate the need for improved mechanistic understanding of exactly what each method is measuring.

  6. Astaxanthin production in marine pelagic copepods grazing on two different phytoplankton diets

    Science.gov (United States)

    Van Nieuwerburgh, Lies; Wänstrand, Ingrid; Liu, Jianguo; Snoeijs, Pauli

    2005-02-01

    The red carotenoid astaxanthin is a powerful natural antioxidant of great importance in aquatic food webs where it is abundant in eggs and body tissues of fish and crustaceans. Little is known about the impact of the phytoplankton diet on astaxanthin production in copepods, its major pelagic producers. We followed the transfer of carotenoids from phytoplankton to copepods in a mesocosm experiment on the northern Atlantic coast (Norway) and recorded the astaxanthin production in copepods. Wild copepods grazed on nutrient-manipulated phytoplankton blooms, which differed in community composition and nutrient status (nitrogen or silicate limitation). The copepod pigments consisted mainly of free astaxanthin and mono- and diesters of astaxanthin. We found no significant difference in astaxanthin production per copepod individual or per unit C depending on the phytoplankton community. However, in the mesocosms astaxanthin per unit C decreased compared with natural levels, probably through a lower demand for photoprotection by the copepods in the dense phytoplankton blooms. The total astaxanthin production per litre was higher in the silicate-limited mesocosms through increased copepod density. Pigment ratio comparisons suggested that the copepod diet here consisted more of diatoms than in the nitrogen-limited mesocosms. Silicate-saturated diatoms were less grazed, possibly because they could invest more in defence mechanisms against their predators. Our study suggests that the production of astaxanthin in aquatic systems can be affected by changes in nutrient dynamics mediated by phytoplankton community composition and copepod population growth. This bottom-up force may have implications for antioxidant protection at higher trophic levels in the food web.

  7. Primary production in a tropical large lake: The role of phytoplankton composition

    Energy Technology Data Exchange (ETDEWEB)

    Darchambeau, F., E-mail: francois.darchambeau@ulg.ac.be [Chemical Oceanography Unit, University of Liège, Liège (Belgium); Sarmento, H., E-mail: hugo.sarmento@gmail.com [Department of Hydrobiology, Federal University of São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Descy, J.-P., E-mail: jean-pierre.descy@unamur.be [Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur (Belgium)

    2014-03-01

    Phytoplankton biomass and primary production in tropical large lakes vary at different time scales, from seasons to centuries. We provide a dataset made of 7 consecutive years of phytoplankton biomass and production in Lake Kivu (Eastern Africa). From 2002 to 2008, bi-weekly samplings were performed in a pelagic site in order to quantify phytoplankton composition and biomass, using marker pigments determined by HPLC. Primary production rates were estimated by 96 in situ {sup 14}C incubations. A principal component analysis showed that the main environmental gradient was linked to a seasonal variation of the phytoplankton assemblage, with a clear separation between diatoms during the dry season and cyanobacteria during the rainy season. A rather wide range of the maximum specific photosynthetic rate (P{sub Bm}) was found, ranging between 1.15 and 7.21 g carbon g{sup −1} chlorophyll a h{sup −1}, and was best predicted by a regression model using phytoplankton composition as an explanatory variable. The irradiance at the onset of light saturation (I{sub k}) ranged between 91 and 752 μE m{sup −2} s{sup −1} and was linearly correlated with the mean irradiance in the mixed layer. The inter-annual variability of phytoplankton biomass and production was high, ranging from 53 to 100 mg chlorophyll a m{sup −2} (annual mean) and from 143 to 278 g carbon m{sup −2} y{sup −1}, respectively. The degree of seasonal mixing determined annual production, demonstrating the sensitivity of tropical lakes to climate variability. A review of primary production of other African great lakes allows situating Lake Kivu productivity in the same range as that of lakes Tanganyika and Malawi, even if mean phytoplankton biomass was higher in Lake Kivu. - Highlights: • We provide a 7-year dataset of primary production in a tropical great lake. • Specific photosynthetic rate was determined by community composition. • Annual primary production varied between 143 and 278 mg C m

  8. Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models

    Science.gov (United States)

    Fu, Weiwei; Randerson, James T.; Moore, J. Keith

    2016-09-01

    We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2-16 % and EP by 7-18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface-ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP. There is considerable variability across the models in the magnitudes of NPP, EP, surface nutrient concentrations and their perturbations by climate change. The negative response of NPP and EP to increasing stratification reflects primarily a bottom-up control, as upward nutrient flux declines at the global scale. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This pattern is driven by phytoplankton community composition shifts, with reductions in productivity by large phytoplankton as smaller phytoplankton (which export less efficiently) are favored under the increasing nutrient stress. Thus, the projections of the NPP response to climate change are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump and the resulting levels of regenerated production, which vary widely across the models. Community structure is represented simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and climate-driven changes in export

  9. Urea as nitrogen source for phytoplankton production in coastal waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.

    Annual variation of urea in coastal waters off Goa, India is 0 to 2.92 mu g-at N.1/1 and 0 to 4.69 mu g-at N.1/1 in adjacent estuarine waters of Mandovi. Peaks of phytoplankton production accompanied with the decrease in urea in June and October...

  10. Phytoplankton absorption predicts patterns in primary productivity in Australian coastal shelf waters

    Science.gov (United States)

    Robinson, C. M.; Cherukuru, N.; Hardman-Mountford, N. J.; Everett, J. D.; McLaughlin, M. J.; Davies, K. P.; Van Dongen-Vogels, V.; Ralph, P. J.; Doblin, M. A.

    2017-06-01

    The phytoplankton absorption coefficient (aPHY) has been suggested as a suitable alternate first order predictor of net primary productivity (NPP). We compiled a dataset of surface bio-optical properties and phytoplankton NPP measurements in coastal waters around Australia to examine the utility of an in-situ absorption model to estimate NPP. The magnitude of surface NPP (0.20-19.3 mmol C m-3 d-1) across sites was largely driven by phytoplankton biomass, with higher rates being attributed to the microplankton (>20 μm) size class. The phytoplankton absorption coefficient aPHY for PAR (photosynthetically active radiation; āPHY)) ranged from 0.003 to 0.073 m-1, influenced by changes in phytoplankton community composition, physiology and environmental conditions. The aPHY coefficient also reflected changes in NPP and the absorption model-derived NPP could explain 73% of the variability in measured surface NPP (n = 41; RMSE = 2.49). The absorption model was applied to two contrasting coastal locations to examine NPP dynamics: a high chlorophyll-high variation (HCHV; Port Hacking National Reference Station) and moderate chlorophyll-low variation (MCLV; Yongala National Reference Station) location in eastern Australia using the GIOP-DC satellite aPHY product. Mean daily NPP rates between 2003 and 2015 were higher at the HCHV site (1.71 ± 0.03 mmol C m-3 d-1) with the annual maximum NPP occurring during the austral winter. In contrast, the MCLV site annual NPP peak occurred during the austral wet season and had lower mean daily NPP (1.43 ± 0.03 mmol C m-3 d-1) across the time-series. An absorption-based model to estimate NPP is a promising approach for exploring the spatio-temporal dynamics in phytoplankton NPP around the Australian continental shelf.

  11. Hydrodynamic control of phytoplankton loss to the benthos in an estuarine environment

    Science.gov (United States)

    Jones, N.L.; Thompson, J.K.; Arrigo, K.R.; Monismith, Stephen G.

    2009-01-01

    Field experiments were undertaken to measure the influence of hydrodynamics on the removal of phytoplankton by benthic grazers in Suisun Slough, North San Francisco Bay. Chlorophyll a concentration boundary layers were found over beds inhabited by the active suspension feeders Corbula amurensis and Corophium alienense and the passive suspension feeders Marenzellaria viridis and Laonome sp. Benthic losses of phytoplankton were estimated via both the control volume and the vertical flux approach, in which chlorophyll a concentration was used as a proxy for phytoplankton biomass. The rate of phytoplankton loss to the bed was positively correlated to the bed shear stress. The maximum rate of phytoplankton loss to the bed was five times larger than estimated by laboratory-derived pumping rates for the active suspension feeders. Reasons for this discrepancy are explored including a physical mechanism whereby phytoplankton is entrained in a near-bed fluff layer where aggregation is mediated by the presence of mucus produced by the infaunal community. ?? 2009, by the American Society of Limnology and Oceanography, Inc.

  12. Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China.

    Science.gov (United States)

    Tian, Chang; Pei, Haiyan; Hu, Wenrong; Hao, Daping; Doblin, Martina A; Ren, Ying; Wei, Jielin; Feng, Yawei

    2015-11-01

    Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations.

  13. A river-scale Lagrangian experiment examining controls on phytoplankton dynamics in the presence and absence of treated wastewater effluent high in ammonium

    Science.gov (United States)

    Kraus, Tamara; Carpenter, Kurt; Bergamaschi, Brian; Parker, Alexander; Stumpner, Elizabeth; Downing, Bryan D.; Travis, Nicole; Wilkerson, Frances; Kendall, Carol; Mussen, Timothy

    2017-01-01

    Phytoplankton are critical component of the food web in most large rivers and estuaries, and thus identifying dominant controls on phytoplankton abundance and species composition is important to scientists, managers, and policymakers. Recent studies from a variety of systems indicate that ammonium ( NH+4) in treated wastewater effluent decreases primary production and alters phytoplankton species composition. However, these findings are based mainly on laboratory and enclosure studies, which may not adequately represent natural systems. To test effects of effluent high in ammonium on phytoplankton at the ecosystem scale, we conducted whole-river–scale experiments by halting discharges to the Sacramento River from the regional wastewater treatment plant (WWTP), and used a Lagrangian approach to compare changes in phytoplankton abundance and species composition in the presence (+EFF) and absence (−EFF) of effluent. Over 5 d of downstream travel from 20 km above to 50 km below the WWTP, chlorophyll concentrations declined from 15–25 to ∼2.5 μg L−1, irrespective of effluent addition. Benthic diatoms were dominant in most samples. We found no significant difference in phytoplankton abundance or species composition between +EFF and −EFF conditions. Moreover, greatest declines in chlorophyll occurred upstream of the WWTP where NH+4 concentrations were low. Grazing by clams and zooplankton could not account for observed losses, suggesting other factors such as hydrodynamics and light limitation were responsible for phytoplankton declines. These results highlight the advantages of conducting ecosystem-scale, Lagrangian-based experiments to understand the dynamic and complex interplay between physical, chemical, and biological factors that control phytoplankton populations.

  14. Optimal Environmental Conditions and Anomalous Ecosystem Responses: Constraining Bottom-up Controls of Phytoplankton Biomass in the California Current System

    Science.gov (United States)

    Jacox, Michael G.; Hazen, Elliott L.; Bograd, Steven J.

    2016-06-01

    In Eastern Boundary Current systems, wind-driven upwelling drives nutrient-rich water to the ocean surface, making these regions among the most productive on Earth. Regulation of productivity by changing wind and/or nutrient conditions can dramatically impact ecosystem functioning, though the mechanisms are not well understood beyond broad-scale relationships. Here, we explore bottom-up controls during the California Current System (CCS) upwelling season by quantifying the dependence of phytoplankton biomass (as indicated by satellite chlorophyll estimates) on two key environmental parameters: subsurface nitrate concentration and surface wind stress. In general, moderate winds and high nitrate concentrations yield maximal biomass near shore, while offshore biomass is positively correlated with subsurface nitrate concentration. However, due to nonlinear interactions between the influences of wind and nitrate, bottom-up control of phytoplankton cannot be described by either one alone, nor by a combined metric such as nitrate flux. We quantify optimal environmental conditions for phytoplankton, defined as the wind/nitrate space that maximizes chlorophyll concentration, and present a framework for evaluating ecosystem change relative to environmental drivers. The utility of this framework is demonstrated by (i) elucidating anomalous CCS responses in 1998-1999, 2002, and 2005, and (ii) providing a basis for assessing potential biological impacts of projected climate change.

  15. Optimal Environmental Conditions and Anomalous Ecosystem Responses: Constraining Bottom-up Controls of Phytoplankton Biomass in the California Current System.

    Science.gov (United States)

    Jacox, Michael G; Hazen, Elliott L; Bograd, Steven J

    2016-06-09

    In Eastern Boundary Current systems, wind-driven upwelling drives nutrient-rich water to the ocean surface, making these regions among the most productive on Earth. Regulation of productivity by changing wind and/or nutrient conditions can dramatically impact ecosystem functioning, though the mechanisms are not well understood beyond broad-scale relationships. Here, we explore bottom-up controls during the California Current System (CCS) upwelling season by quantifying the dependence of phytoplankton biomass (as indicated by satellite chlorophyll estimates) on two key environmental parameters: subsurface nitrate concentration and surface wind stress. In general, moderate winds and high nitrate concentrations yield maximal biomass near shore, while offshore biomass is positively correlated with subsurface nitrate concentration. However, due to nonlinear interactions between the influences of wind and nitrate, bottom-up control of phytoplankton cannot be described by either one alone, nor by a combined metric such as nitrate flux. We quantify optimal environmental conditions for phytoplankton, defined as the wind/nitrate space that maximizes chlorophyll concentration, and present a framework for evaluating ecosystem change relative to environmental drivers. The utility of this framework is demonstrated by (i) elucidating anomalous CCS responses in 1998-1999, 2002, and 2005, and (ii) providing a basis for assessing potential biological impacts of projected climate change.

  16. The importance of phytoplankton production for carbon budgets in a semiarid floodplain wetland

    Directory of Open Access Journals (Sweden)

    Álvarez-Cobelas, Miguel

    2011-12-01

    Full Text Available Phytoplankton production (PP in wetlands is not measured as often as that of macrophytes. A three year-study during a period of sustained high flooding was undertaken in a central Spanish floodplain wetland (Las Tablas de Daimiel National Park to determine net PP, its spatial heterogeneity and controlling factors, and compare it with primary production in macrophyte communities. This enabled us to estimate carbon budgets for each community. All PP variables showed high spatial and temporal variability among sites, resulting in low coherence even when flooding connected all sites. Net PP corresponded to 25- 36% of submerged plant production and 3-10% of helophyte production. Net PP was controlled by different size fractions of phytoplankton biomass at different wetland sites. Neither nutrients nor zooplankton affected net PP or productivity. A high spatiotemporal variability of PP in wetlands occurs arising from complex processes that affect the underwater light field. Carbon budgets of phytoplankton often exceeded those of submerged macrophytes and attained between 4 and 37% of helophyte budgets. Although usually considered to be marginal, our study shows that PP in the open water of wetlands should be taken into account for determining accurate wetland carbon budgets, mostly in periods of high flooding, which often result in changing the carbon budget of primary producers.

    La producción de fitoplancton (PF en los humedales no se mide tan a menudo como la de los macrófitos. En este estudio se lleva a cabo un trabajo de tres años durante un periodo de gran inun dación en un humedal de llanura de inundación (Parque Nacional de Las Tablas de Daimiel a fin de determinar la producción neta del fitoplancton, su heterogeneidad espacial y los factores que la controlan. También comparamos la PF con la producción primaria de las comunidades de macrófitos, lo cual nos permite estimar las cantidades de carbono que fija cada comunidad vegetal

  17. Production of Biodiesel from Lipid of Phytoplankton Chaetoceros calcitrans through Ultrasonic Method

    Directory of Open Access Journals (Sweden)

    Raymond Kwangdinata

    2014-01-01

    Full Text Available A research on production of biodiesel from lipid of phytoplankton Chaetoceros calcitrans through ultrasonic method has been done. In this research, we carried out a series of phytoplankton cultures to determine the optimum time of growth and biodiesel synthesis process from phytoplankton lipids. Process of biodiesel synthesis consists of two steps, that is, isolation of phytoplankton lipids and biodiesel synthesis from those lipids. Oil isolation process was carried out by ultrasonic extraction method using ethanol 96%, while biodiesel synthesis was carried out by transesterification reaction using methanol and KOH catalyst under sonication. Weight of biodiesel yield per biomass Chaetoceros calcitrans is 35.35%. Characterization of biodiesel was well carried out in terms of physical properties which are density and viscosity and chemical properties which are FFA content, saponification value, and iodine value. These values meet the American Society for Testing and Materials (ASTM D6751 standard levels, except for the viscosity value which was 1.14 g·cm−3.

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

    Science.gov (United States)

    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.

  19. Lack of seasonality in phytoplankton standing stock (chlorophyll a) and production in the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Madhu, N.V.; Jyothibabu, R.; Maheswaran, P.A.; Gerson, V.J.; Gopalakrishnan, T.C.; Nair, K.K.C.

    The investigations in the western Bay of Bengal (BoB) during summer, winter and spring intermonsoon periods evidenced lack of pronounced seasonal variation in phytoplankton standing stock (chlorophyll a) and primary production. The supply...

  20. Winter and spring phytoplankton composition and production in a shallow eutrophic Baltic lagoon

    Science.gov (United States)

    Schumann, R.; Hammer, A.; Görs, S.; Schubert, H.

    2005-01-01

    Taxonomic composition and productivity of winter and spring phytoplankton in a eutrophic estuary have been investigated in order to elucidate the carbon flux under conditions of limitation by physical factors - light and temperature. In spite of the important differences in nutrients, solar radiation and water temperature between winter and spring season, mean concentrations of particulate organic carbon were equal to 13.2 and 13.0 mgC l -1, respectively. Chlorophyll a averaged at 79 μgChl l -1 in winter, that is 69% of spring. Although community respiration accounted for only 6-26% of light saturated photosynthesis, integrated net primary production of the 1.2 m deep water column was negative until April. High attenuation of the water body ( Ko = 2.9 m -1) lead to a negative carbon balance (net heterotrophy) below 35 cm for all sampling dates. Thus, the high winter POC and phytoplankton values can only originate from summer or autumn primary production. This assumption was supported by a carbon loss rate of just 3% of total organic carbon per day for the whole water column. The composition of phytoplankton was very constant through both seasons: 39% Chlorophyceae, 33% Cyanobacteria and 25% Bacillariophyceae. As expected, phytoplankton was low light acclimated, having high α values (slope of light limited photosynthesis), but moderate maximum photosynthesis rates at saturating irradiances, which were heavily affected by temperature. Calculation of net carbon flux yet showed net heterotrophy of the Bodden waters in winter and early spring were caused by external physical limitation (low surface irradiance and low temperature) in combination with a high light attenuation of the water body.

  1. Influence of anomalous subarctic water intrusion on phytoplankton production off Baja California

    Science.gov (United States)

    Espinosa-Carreón, T. L.; Gaxiola-Castro, G.; Durazo, R.; De la Cruz-Orozco, M. E.; Norzagaray-Campos, M.; Solana-Arellano, E.

    2015-01-01

    The southern region of the California Current (CC) off Baja California represents a transitional environment, with the influence of low temperature and less saline CC water during spring and summer, and warm and salty tropical and subtropical conditions through the end of summer and autumn. From 2002 to 2006, an anomalous subarctic water (SAW) intrusion generated changes in the epipelagic ecosystem dynamics, affecting phytoplankton biomass and primary production. The goal of the present work is to show the effects of the SAW intrusion off Baja California in the phytoplankton production during the two contrasting years 2002 and 2005. Our results show that the minimum water salinity was associated with density levels of 24.6-25.5 kg m-3 in 2002 and 24.3-25.2 kg m-3 in 2005, indicating that the anomalous SAW intrusion was more pronounced in 2005. In 2005, the mean chlorophyll concentration was low (1.0 mg m-3 in some months. CHL values were significantly different between the north and south zone and among months (p<0.01). The mean values of the photosynthetic parameters (maximum light utilization coefficient (αB) and maximum photosynthesis rate (PBm)) were one order of magnitude higher in 2005 compared to 2002 (p<0.01). The primary production estimated by the Herman and Platt model and the Carr model was very different in 2002 (mean values of 907 and 143 mgC m-2 d-1 respectively), but similar in 2005 (750 and 1006 mgC m-2 d-1 respectively). The differences between models may be due to the diverse chlorophyll data used in the singular models (in situ vs. satellite-derived), and to the weight of the phytoplankton photosynthetic parameters in each algorithm. We conclude that for the present data set the Herman and Platt model is more suitable. To assess the relative importance of physical variables, as well as bio-optical and physiological parameters in primary production, we conducted a principal component analysis (PCA). There was an apparent separation between the

  2. Approach for estimating the dynamic physical thresholds of phytoplankton production and biomass in the tropical-subtropical Pacific Ocean

    Science.gov (United States)

    Gómez-Ocampo, E.; Gaxiola-Castro, G.; Durazo, Reginaldo

    2017-06-01

    Threshold is defined as the point where small changes in an environmental driver produce large responses in the ecosystem. Generalized additive models (GAMs) were used to estimate the thresholds and contribution of key dynamic physical variables in terms of phytoplankton production and variations in biomass in the tropical-subtropical Pacific Ocean off Mexico. The statistical approach used here showed that thresholds were shallower for primary production than for phytoplankton biomass (pycnocline topography and Ekman pumping (ADT 0 cm d-1 versus ADT 4 cm d-1). The relatively high productivity on seasonal (spring) and interannual (La Niña 2008) scales was linked to low ADT (45-60 cm) and shallow pycnocline depth (9-68 m) and mixed layer (8-40 m). Statistical estimations from satellite data indicated that the contributions of ocean circulation to phytoplankton variability were 18% (for phytoplankton biomass) and 46% (for phytoplankton production). Although the statistical contribution of models constructed with in situ integrated chlorophyll a and primary production data was lower than the one obtained with satellite data (11%), the fits were better for the former, based on the residual distribution. The results reported here suggest that estimated thresholds may reliably explain the spatial-temporal variations of phytoplankton in the tropical-subtropical Pacific Ocean off the coast of Mexico.

  3. Diagnosis of Physical and Biological Controls on Phytoplankton Distribution in the Sargasso Sea

    Institute of Scientific and Technical Information of China (English)

    WANG Caixia; Paola Malanotte-Rizzoli

    2014-01-01

    The linkage between physical and biological processes is studied by applying a one-dimensional physical-biological coupled model to the Sargasso Sea. The physical model is the Princeton Ocean Model and the biological model is a five-component system including phytoplankton, zooplankton, nitrate, ammonium, and detritus. The coupling between the physical and biological model is accomplished through vertical mixing which is parameterized by the level 2.5 Mellor and Yamada turbulence closure scheme. The coupled model investigates the annual cycle of ecosystem production and the response to external forcing, such as heat flux, wind stress, and surface salinity, and the relative importance of physical processes in affecting the ecosystem. Sensitivity ex-periments are also carried out, which provide information on how the model bio-chemical parameters affect the biological system. The computed seasonal cycles compare reasonably well with the observations of the Bermuda Atlantic Time-series Study (BATS). The spring bloom of phytoplankton occurs in March and April, right after the weakening of the winter mixing and before the estab-lishment of the summer stratification. The bloom of zooplankton occurs about two weeks after the bloom of phytoplankton. The sen-sitivity experiments show that zooplankton is more sensitive to the variations of biochemical parameters than phytoplankton.

  4. Effects of dust additions on phytoplankton growth and DMS production in high CO2 northeast Pacific HNLC waters

    Directory of Open Access Journals (Sweden)

    J. Mélançon

    2015-08-01

    Full Text Available 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 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 % of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15 % reduction in particulate organic carbon (POC concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. 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.

  5. Effects of dust additions on phytoplankton growth and DMS production in high CO2 northeast Pacific HNLC waters

    Science.gov (United States)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M.; Tremblay, J.-É.; Tortell, P.; Yang, G.-P.; Shi, G.-Y.; Gao, H.-W.; Semeniuk, D. M.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Peña, A.; Richardson, W.

    2015-08-01

    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 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 %) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15 % reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. 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.

  6. Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem

    Science.gov (United States)

    Kämpf, J.

    2015-01-01

    Satellite-derived chlorophyll a data using the standard NASA-OC3 (ocean colour) algorithm are strongly biased by coloured dissolved organic matter and suspended sediment of river discharges, which is a particular problem for the western Tasmanian shelf. This work reconstructs phytoplankton blooms in the study region using a quadratic regression between OC3 data and chlorophyll fluorescence based on the fluorescence line height (FLH) data. This regression is derived from satellite data of the nearby Bonney upwelling region, which is devoid of river influences. To this end, analyses of 10 years of MODIS-aqua satellite data reveal the existence of a highly productive ecosystem on the western Tasmanian shelf. The region normally experiences two phytoplankton blooms per annum. The first bloom occurs during late austral summer months as a consequence of upwelling-favourable coastal winds. Hence, the western Tasmanian shelf forms a previously unknown upwelling centre of the regional upwelling system, known as Great South Australian Coastal Upwelling System. The second phytoplankton bloom is a classical spring bloom also developing in the adjacent Tasman Sea. The author postulates that this region forms another important biological hot spot for the regional marine ecosystem.

  7. Effects of chemical ecological adjustment and control experiment on phytoplankton community in the Aoshan Bay

    Institute of Scientific and Technical Information of China (English)

    陈碧鹃; 赵俊; 辛福言; 崔毅; 过锋

    2002-01-01

    There is a low nutrient level in the Aoshan Bay. In June 1999, the chemical adjustment and control experiment was made in the Aoshan Bay. Following tracts investigation was carried out before the experiment and on the 1st, 2nd, 4th, 5th, 6th and 45th day/after the experiment. While the variance of amount of phytoplankton, the replacement of superior species and the species composition of phytoplankton were researched. The results show that the amount of phytoplankton in the Aoshan Bay rises gradually after the experiment. Ceratium macroceros Cleve of pyrophyta was the dominant species before the experiment, its dominant index was 37.7%. Six days after the experiment, its dominant index dropped to 17.6%. Meanwhile the dominant index of Asterionella japonics Cleve rose from 7.1% to 39.2%, it became the first dominant species. Forty-five days after the experiment, the amount of phytoplankton in the Aoshan Bay was 5.15 to 137.32 times more than that in 1997.

  8. Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs

    Directory of Open Access Journals (Sweden)

    Baoli Wang

    2013-02-01

    Full Text Available In order to systematically understand the mechanisms controlling the carbon stable isotope composition of phytoplankton (δ13CPHYin freshwater ecosystems, seasonal changes in δ13CPHY and related environmental factors were determined in karst reservoirs from the Wujiang river basin, China. Substantial and systematic differences within seasons and reservoirs were observed for δ13CPHY, which ranged from -39.2‰ to -15.1‰. An increase in water temperature triggered fast growth of phytoplankton which assimilated more dissolved inorganic carbon (DIC, resulting in the increase of δ13CPHY, δ13CDIC and pH. When the concentration of dissolved carbon dioxide (CO2 was less than 10 mmol L–1, phytoplankton shifted to using HCO3– as a carbon source. This resulted in the sharp increase of δ13CPHY. The carbon stable isotope composition of phytoplankton tended to decrease with the increase of Bacillariophyta, which dominated in January and April, but tended to increase with the increase of Chlorophyta and Dinophyta, which dominated in July. Multiple regression equations suggested that the influence of biological factors such as taxonomic difference on δ13CPHY could be equal or more important than that of physical and chemical factors. Thus, the effect of taxonomic differences on δ13CPHY must be considered when explaining the δ13C of organic matter in lacustrine ecosystem.

  9. The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study.

    Science.gov (United States)

    Yap, Leni G; Azanza, Rhodora V; Talaue-McManus, Liana

    2004-11-01

    From 1995 up to the present, fish pens proliferated in the municipal waters of Bolinao, northern Philippines. Since then, fish kills and phytoplankton blooms have been recurrent. Have fishpens altered the phytoplankton community composition and production of these waters? The phytoplankton community in Cape Bolinao, Lingayen Gulf is typical of a tropical coastal area where diatoms alternate with dinoflagellates during the dry and wet seasons. In the nutrient-rich fish pens, phytoplankton in this study showed a lower diatom/dinoflagellate ratio and unusually high phytoplankton counts of 10(4) cells/l and even as high as 10(5) cells/l. Correlations between physico-chemical parameters, phytoplankton production and community composition were made in 2001. This paper tried to explain the occurrence of a Cylindrotheca closterium bloom (10(5) cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 x 10(5) cells/l), which accompanied a massive fish kill during January 2002.

  10. The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Leni G. [University of the Philippines in the Visayas, Tacloban College, Tacloban City, Leyte 6500 (Philippines)]. E-mail: leni@upmsi.ph; Azanza, Rhodora V. [Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101 (Philippines)]. E-mail: rhod@upmsi.ph; Talaue-McManus, Liana [Division of Marine Affairs, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 (United States)]. E-mail: lmcmanus@rsmas.miami.edu

    2004-11-01

    From 1995 up to the present, fish pens proliferated in the municipal waters of Bolinao, northern Philippines. Since then, fish kills and phytoplankton blooms have been recurrent. Have fishpens altered the phytoplankton community composition and production of these waters? The phytoplankton community in Cape Bolinao, Lingayen Gulf is typical of a tropical coastal area where diatoms alternate with dinoflagellates during the dry and wet seasons. In the nutrient-rich fish pens, phytoplankton in this study showed a lower diatom/dinoflagellate ratio and unusually high phytoplankton counts of 10{sup 4} cells/l and even as high as 10{sup 5} cells/l. Correlations between physico-chemical parameters, phytoplankton production and community composition were made in 2001. This paper tried to explain the occurrence of a Cylindrotheca closterium bloom (10{sup 5} cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 x 10{sup 5} cells/l), which accompanied a massive fish kill during January 2002.

  11. Phytoplankton dynamics of a subtropical reservoir controlled by the complex interplay among hydrological, abiotic, and biotic variables.

    Science.gov (United States)

    Kuo, Yi-Ming; Wu, Jiunn-Tzong

    2016-12-01

    This study was conducted to identify the key factors related to the spatiotemporal variations in phytoplankton abundance in a subtropical reservoir from 2006 to 2010 and to assist in developing strategies for water quality management. Dynamic factor analysis (DFA), a dimension-reduction technique, was used to identify interactions between explanatory variables (i.e., environmental variables) and abundance (biovolume) of predominant phytoplankton classes. The optimal DFA model significantly described the dynamic changes in abundances of predominant phytoplankton groups (including dinoflagellates, diatoms, and green algae) at five monitoring sites. Water temperature, electrical conductivity, water level, nutrients (total phosphorus, NO3-N, and NH3-N), macro-zooplankton, and zooplankton were the key factors affecting the dynamics of aforementioned phytoplankton. Therefore, transformations of nutrients and reactions between water quality variables and aforementioned processes altered by hydrological conditions may also control the abundance dynamics of phytoplankton, which may represent common trends in the DFA model. The meandering shape of Shihmen Reservoir and its surrounding rivers caused a complex interplay between hydrological conditions and abiotic and biotic variables, resulting in phytoplankton abundance that could not be estimated using certain variables. Additional water quality and hydrological variables at surrounding rivers and monitoring plans should be executed a few days before and after reservoir operations and heavy storm, which would assist in developing site-specific preventive strategies to control phytoplankton abundance.

  12. Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem

    Directory of Open Access Journals (Sweden)

    J. Kämpf

    2014-09-01

    Full Text Available Analyses of >10 years of satellite-derived ocean-color data reveal the existence of a highly productive ecosystem on the west Tasmanian shelf. A closer event-based analysis indicates that the nutrient supply for this system has two different dynamical origins: (a wind-driven coastal upwelling and (b river plumes. During austral summer months, the west Tasmanian shelf forms a previously unknown upwelling center of the "Great South Australian Coastal Upwelling System", presumably injecting nutrient-rich water into western Bass Strait. Surprisingly, river discharges render the study region productive during other seasons of the year, except when nutrient-poor water of the South Australian Current reaches the region. Overall, the west Tasmanian shelf is more phytoplankton-productive than the long-known coastal upwelling along the Bonney Coast. The existence of phytoplankton blooms during the off-upwelling-season may explain the wintertime spawing aggregations of the blue grenadier (Macruronus novaezelandiae and the associated regionally high abundance of Australian fur seals (Arctocephalus pusillus doriferus.

  13. The effect of coastal processes on phytoplankton biomass and primary production within the near-shore Subtropical Frontal Zone

    Science.gov (United States)

    Jones, Katherine N.; Currie, Kim I.; McGraw, Christina M.; Hunter, Keith A.

    2013-06-01

    This study evaluated drivers of phytoplankton net primary production (NPP) rates and chlorophyll-a (chl-a) concentrations within the coastally oriented Subtropical Frontal Zone (STFZ) off the South Island of New Zealand. Time series measurements of hydrographic parameters, macronutrients, size fractionated NPP and chl-a were conducted on a bi-monthly basis from July 2009 to November 2010. This study found that nutrient limitation in these waters is controlled by the dual influx of silicate inputs from riverine sources in coastal neritic water (NW) and oceanic inputs of nitrate from the high nutrient, low chlorophyll (HNLC) region of the offshore Sub-Antarctic Surface Waters (SASW). Total chl-a concentrations and primary production rates were perennially higher in near-shore NW and modified Subtropical waters (STW) than in the SASW, with highest indicators of biological production observed in the Austral spring and summer seasons (October to March). These periods of peak production and biomass were dominated in both parameters by microphytoplankton (>20 μm) size fractions. The coupled dominance by these large phytoplankton and the near depletion of silicate in all characterised waters within the frontal system indicate the importance of silicic diatoms as drivers of bloom production. The influence of coastal waters on the STFZ system is most pronounced with the intrusion of neritic water beyond the shelf boundary during periods of surface water thermal stratification and riverine dilution through flooding events. These two events were notably observed during the Spring 2009 sampling cruise in December 2009 and in the flood event in May 2010.

  14. Seasonal and interannual phytoplankton production in a sub-arctic tidewater outlet glacier fjord, west Greenland

    DEFF Research Database (Denmark)

    Juul-Pedersen, T.; Arendt, K.; Mortensen, J.

    2015-01-01

    This study describes seasonal patterns and proposes likely drivers of an unusual phytoplankton primary production pattern in the outer-sill region of a tidewater outlet glacierinfluenced fjord (Godthåbsfjord) in SW Greenland. It is based on monthly measurements of pelagic primary production...... in a water column almost fully mixed due to tidal forces at the fjord sill. After the spring bloom, primary production decreased in June, after which a summer bloom of up to 1383 mg C m−2 d−1 built up. This bloom coincided with the development of a pycnocline caused by substantial runoff from the Greenland...... Ice Sheet every year during midsummer. This observation supports a hypothesis that fjord circulation modes and subglacial freshwater discharge, leading to upwelling of nutrient rich water, stimulate primary production in the fjord. Future changes in the timing or magnitude of meltwater runoff from...

  15. Delineating environmental control of phytoplankton biomass and phenology in the Southern Ocean

    Science.gov (United States)

    Ardyna, Mathieu; Claustre, Hervé; Sallée, Jean-Baptiste; D'Ovidio, Francesco; Gentili, Bernard; van Dijken, Gert; D'Ortenzio, Fabrizio; Arrigo, Kevin R.

    2017-05-01

    The Southern Ocean (SO), an area highly sensitive to climate change, is currently experiencing rapid warming and freshening. Such drastic physical changes might significantly alter the SO's biological pump. For more accurate predictions of the possible evolution of this pump, a better understanding of the environmental factors controlling SO phytoplankton dynamics is needed. Here we present a satellite-based study deciphering the complex environmental control of phytoplankton biomass (PB) and phenology (PH; timing and magnitude of phytoplankton blooms) in the SO. We reveal that PH and PB are mostly organized in the SO at two scales: a large latitudinal scale and a regional scale. Latitudinally, a clear gradient in the timing of bloom occurrence appears tightly linked to the seasonal cycle in irradiance, with some exceptions in specific light-limited regimes (i.e., well-mixed areas). Superimposed on this latitudinal scale, zonal asymmetries, up to 3 orders of magnitude, in regional-scale PB are mainly driven by local advective and iron supply processes. These findings provide a global understanding of PB and PH in the SO, which is of fundamental interest for identifying and explaining ongoing changes as well as predicting future changes in the SO biological pump.

  16. Impacts of sea ice on the marine iron cycle and phytoplankton productivity

    Directory of Open Access Journals (Sweden)

    S. Wang

    2014-02-01

    Full Text Available Iron is a key nutrient for phytoplankton growth in the surface ocean. At high latitudes, the iron cycle is closely related to sea ice. In recent decades, Arctic sea ice cover has been declining rapidly and Antarctic sea ice has exhibited large regional trends. A significant reduction of sea ice in both hemispheres is projected in future climate scenarios. To study impacts of sea ice on the iron cycle, iron sequestration in ice is incorporated to the Biogeochemical Elemental Cycling (BEC model. Sea ice acts as a reservoir of iron during winter and releases iron to the surface ocean in spring and summer. Simulated iron concentrations in sea ice generally agree with observations, in regions where iron concentrations are lower. The maximum iron concentrations simulated in the Arctic sea ice and the Antarctic sea ice are 192 nM and 134 nM, respectively. These values are much lower than observed, which is likely due to missing biological processes in sea ice. The largest iron source to sea ice is suspended sediments, contributing fluxes of iron of 2.2 × 108 mol Fe month−1 to the Arctic and 4.1 × 106 mol Fe month−1 to the Southern Ocean during summer. As a result of the iron flux from ice, iron concentrations increase significantly in the Arctic. Iron released from melting ice increases phytoplankton production in spring and summer and shifts phytoplankton community composition in the Southern Ocean. Simulation results for the period of 1998 to 2007 indicate that a reduction of sea ice in the Southern Ocean will have a negative influence on phytoplankton production. Iron transport by sea ice appears to be an important process bringing iron to the central Arctic. Impacts of iron fluxes from ice to ocean on marine ecosystems are negligible in the current Arctic Ocean, as iron is not typically the growth-limiting nutrient. However, it may become a more important factor in the future, particularly in the central Arctic, as iron concentrations will

  17. Phytoplankton production and physiological adaptation on the southeastern shelf of the Agulhas ecosystem

    Science.gov (United States)

    Barlow, R.; Lamont, T.; Kyewalyanga, M.; Sessions, H.; Morris, T.

    2010-07-01

    An investigation of phytoplankton production and physiology was undertaken during two research cruises on the southeastern shelf of southern Africa. The data set included photosynthesis-irradiance and active fluorescence parameters, phytoplankton absorption coefficients and HPLC pigment concentrations. Primary production was estimated to vary over a similar range for both cruises within 0.27-3.69 g C m -2 d -1. Pigment indices indicated that diatoms were dominant on the first cruise and the communities were subject to conditions where the mixed layer was deeper than the euphotic zone and they optimized their photosynthesis to very low light intensities at the bottom and below the euphotic zone. Mixed diatom-flagellate populations were observed during the second cruise where the euphotic zone was deeper than the mixed layer and the populations adapted to irradiances higher in the euphotic zone. In response to a mean lower water column PAR, it was found that these mixed communities increased the proportion of chlorophyll a in the pigment pool and had a higher quantum yield of photochemistry and higher light-limited photosynthetic efficiency.

  18. Large variability in continental shelf production of phytoplankton carbon revealed by satellite

    Directory of Open Access Journals (Sweden)

    B. F. Jönsson

    2010-12-01

    Full Text Available We estimate the net production of phytoplankton in the Gulf of Maine (GoM over a 3-year period using satellite ocean color data in conjunction with surface velocities from a high-resolution operational ocean circulation model. Chlorophyll (chl-a and light attenuation (K490 products are combined with a carbon to chlorophyll model to estimate the phytoplankton carbon (PC stock in the euphotic layer. A satellite-based productivity, termed NCPe in analogy with net community production (NCP, is derived by tracking changes in satellite-derived PC from one satellite image to the next, along water parcel trajectories calculated with surface velocities from the ocean circulation model. Such an along-trajectory analysis of satellite data discounts the effect of advection that would otherwise contribute to the temporal change between consecutive images viewed in the fixed reference frame. Our results show a high variability of up to ± 500 mg C m−2 d−1 in NCPe on spatial scales of 10–100 km. A region-wide median NCPe of 40–50 mg C m−2 d−1 is often prevalent in the Gulf, while blooms attain peak values of 400 mg C m−2 d−1 for a few days. The spatio-temporal variability of NCPe in this region, though conditioned by seasonality, is dominated by events lasting a few days, which if integrated, lead to large inter-annual variability in the annual carbon budget. This study is a step toward achieving synoptic and time-dependent estimates of oceanic productivity and NCP from satellite data.

  19. Seasonal changes of phytoplankton production in response to high nitrogen load in the Bay of Seine

    Science.gov (United States)

    L Helguen, S.; Maguer, J.-F.; Madec, C.

    2003-04-01

    Seasonal changes of uptake of nitrogenous nutrients and regeneration were investigated in nitrogen rich waters of the Bay of Seine. Uptake of nitrogen nutrients (NO_3-, NH_4^+ and urea), and NH_4^+ regeneration, were measured using the 15N isotope technique in three different water masses along a salinity gradient (salinity: 27-29, 31-32 and 34-35). The Seine river add very high quantities of inorganic nitrogen to the coastal waters mainly in the form of nitrate (up to 120 μmol l-1). In the plume, the nitrate concentration remained high (> 10 μmol l-1) during all the seasons. In these nitrate enrich waters, phytoplankton attained high biomass (20-25 μg chla l-1). Species succession was marked by blooms formation from the beginning of spring until the end of summer. The high biomass was represented by microplankton generally dominated by diatom species during all the seasons. However, nano- and picoplankton biomass increased significantly during the summer and represented up to 50% of the total biomass of phytoplankton. Nitrogen uptake rates were higher in the Seine Bay plume (0.5 μmol l-1 h-1) than the other coastal waters. Although, the N uptake was high, it was limited by light, which was due to the high turbidity and strong vertical mixing in these plume waters. The seasonal variations in nitrogen uptake demonstrated that during spring, up to 80% of nitrogen was utilized by microplancton whereas in summer, all the fractions utilized nitrogen significantly. In spring, nitrate was the major nitrogen nutrient taken up (˜ 80% of total nitrogen uptake). During other seasons, ammonium and urea were the highly utilized nitrogen compounds (up to 95% of total nitrogen uptake). Ammonium regeneration by microhétérotrophs increased significantly in the plume waters during the spring bloom and remained high (> 0.1 μmol l-1 h-1) until the end of summer. The high and prolonged use of NH_4^+ was due to high autochthonous production, fulfil 40 to 100% of NH_4^+ demand of

  20. Measuring phytoplankton primary production: review of existing methodologies and suggestions for a common approach. EcApRHA Deliverable WP 3.2

    NARCIS (Netherlands)

    Kromkamp, J.; Capuzzo, E.; Philippart, C.J.M.

    2017-01-01

    Executive SummaryThe importance of the phytoplankton production indicator is clearly stated in the MSFD‐Foodweb homepage1: “the phytoplankton production indicator can reflect several pressures (e. g. hydrological changes,contaminants, nutrient inputs or climate changes). Hence, this indicator is hig

  1. Solar irradiance changes and phytoplankton productivity in Earth's ocean following astrophysical ionizing radiation events

    CERN Document Server

    Neale, Patrick J

    2016-01-01

    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 developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and remote-sensing based observations of spectral water transparency, temperature, wind speed and mixed...

  2. Seasonal patterns in phytoplankton photosynthetic parameters and primary production at a coastal NW Mediterranean site

    KAUST Repository

    Gasol, Josep M.

    2016-10-11

    We carried out monthly photosynthesis-irradiance (P-E) experiments with the 14C-method for 12 years (2003–2014) to determine the photosynthetic parameters and primary production of surface phytoplankton in the Blanes Bay Microbial Observatory, a coastal sampling station in the NW Mediterranean Sea. Our goal was to obtain seasonal trends and to establish the basis for detecting future changes of primary production in this oligotrophic area. The maximal photosynthetic rate PBmax ranged 30-fold (0.5-15 mg C mg Chl a–1 h–1), averaged 3.7 mg C mg Chl a–1 h–1 (±0.25 SE) and was highest in August and lowest in April and December. We only observed photoinhibition twice. The initial or light-limited slope of the P-E relationship, αB, was low, averaging 0.007 mg C mg Chl a–1 h–1 (μmol photons m–2 s–1)–1 (±0.001 SE, range 0.001-0.045) and showed the lowest values in spring (April-June). The light saturation parameter or saturation irradiance, EK, averaged 711 μmol photons m–2 s–1 (±58.4 SE) and tended to be higher in spring and lower in winter. Phytoplankton assemblages were typically dominated by picoeukaryotes in early winter, diatoms in late autumn and late winter, dinoflagellates in spring and cyanobacteria in summer. Total particulate primary production averaged 1.45 mg C m–3 h–1 (±0.13 SE) with highest values in winter (up to 8.50 mg C m–3 h–1) and lowest values in summer (summer average, 0.30 mg C m–3 h–1), while chlorophyll-specific primary production averaged 2.49 mg C mg Chl a–1 h–1 (±0.19, SE) and peaked in summer (up to 12.0 mg C mg Chl a–1 h–1 in August). 14C-determined phytoplankton growth rates varied between ca. 0.3 d–1 in winter and 0.5 d–1 in summer and were within 60-80% of the maximal rates of growth, based on PBmax. Chlorophyll a was a good predictor of primary production only in the winter and autumn. Seasonality appeared to explain most of the variability in the studied variables, while

  3. Seasonal patterns in phytoplankton photosynthetic parameters and primary production at a coastal NW Mediterranean site

    Directory of Open Access Journals (Sweden)

    Josep M. Gasol

    2016-09-01

    Full Text Available We carried out monthly photosynthesis-irradiance (P-E experiments with the 14C-method for 12 years (2003–2014 to determine the photosynthetic parameters and primary production of surface phytoplankton in the Blanes Bay Microbial Observatory, a coastal sampling station in the NW Mediterranean Sea. Our goal was to obtain seasonal trends and to establish the basis for detecting future changes of primary production in this oligotrophic area. The maximal photosynthetic rate PBmax ranged 30-fold (0.5-15 mg C mg Chl a–1 h–1, averaged 3.7 mg C mg Chl a–1 h–1 (±0.25 SE and was highest in August and lowest in April and December. We only observed photoinhibition twice. The initial or light-limited slope of the P-E relationship, αB, was low, averaging 0.007 mg C mg Chl a–1 h–1 (μmol photons m–2 s–1–1 (±0.001 SE, range 0.001-0.045 and showed the lowest values in spring (April-June. The light saturation parameter or saturation irradiance, EK, averaged 711 μmol photons m–2 s–1 (± 58.4 SE and tended to be higher in spring and lower in winter. Phytoplankton assemblages were typically dominated by picoeukaryotes in early winter, diatoms in late autumn and late winter, dinoflagellates in spring and cyanobacteria in summer. Total particulate primary production averaged 1.45 mg C m-3 h–1 (±0.13 SE with highest values in winter (up to 8.50 mg C m-3 h–1 and lowest values in summer (summer average, 0.30 mg C m-3 h–1, while chlorophyll-specific primary production averaged 2.49 mg C mg Chl a–1 h–1 (±0.19, SE and peaked in summer (up to 12.0 mg C mg Chl a–1 h–1 in August. 14C-determined phytoplankton growth rates varied between ca. 0.3 d–1 in winter and 0.5 d–1 in summer and were within 60-80% of the maximal rates of growth, based on PBmax. Chlorophyll a was a good predictor of primary production only in the winter and autumn. Seasonality appeared to explain most of the variability in the studied variables, while

  4. Seasonal and interannual phytoplankton production in a sub-arctic tidewater outlet glacier fjord, west Greenland

    DEFF Research Database (Denmark)

    Juul-Pedersen, T.; Arendt, K.; Mortensen, J.;

    2015-01-01

    and hydrographic conditions during a 7 yr period. Total annual primary production during 2005 to 2012 was between 84.6 and 139.1 g C m−2 yr−1. Two phytoplankton blooms of similar magnitude reoccur in the fjord every year. A ‘classical’ spring bloom of up to 1743 mg C m−2 d−1 occurred in late April/early May...... in a water column almost fully mixed due to tidal forces at the fjord sill. After the spring bloom, primary production decreased in June, after which a summer bloom of up to 1383 mg C m−2 d−1 built up. This bloom coincided with the development of a pycnocline caused by substantial runoff from the Greenland...

  5. Influence of hydrography on the spatiotemporal variability of phytoplankton assemblages and primary productivity in Funka Bay and the Tsugaru Strait

    Science.gov (United States)

    Isada, Tomonori; Hirawake, Toru; Nakada, Satoshi; Kobayashi, Tsukuru; Sasaki, Ken'ichi; Tanaka, Yoshiyuki; Watanabe, Shuichi; Suzuki, Koji; Saitoh, Sei-Ichi

    2017-03-01

    Phytoplankton community structures and primary productivity were assessed in relation to the oceanographic conditions in the coastal waters of Funka bay and the eastern end of the Tsugaru Strait, adjacent to southwestern Hokkaido, Japan, from April 2010 to January 2012. Phytoplankton community compositions, as estimated from chemotaxonomic analysis based on high-performance liquid chromatography of pigments, showed diatom blooms during spring in both 2010 and 2011. However, spatial heterogeneity of chlorophyll a (Chl a) concentration and primary productivity were found between regions investigated within and outside of Funka Bay during the spring diatom blooms in April 2010. The low Chl a concentrations within Funka Bay in April 2010 were related to the depletion of dissolved inorganic macronutrients, which implies that this difference was related to both the small inflow of the cold Coastal Oyashio Current (COW) into the bay and the development of clockwise circulation caused by discharge of fresh water into the bay. After the spring diatom blooms, the major phytoplankton groups in the study area were Chl b-containing phytoplanktons (chlorophytes and prasinophytes) because of changes in salinity associated with river discharge during the melting season. The results indicate that these phytoplanktons play an important role in the carbon cycle after the spring bloom in Funka Bay and the eastern end of the Tsugaru Strait. The thermohaline fronts created by the COW and the Tsugaru Warm Water in late February produced north-south differences in phytoplankton community structures in the eastern end of the Tsugaru Strait. Diatoms with high Chl a concentrations dominated in the northern section of the front. In the southern section, the proportions of chlorophytes and cryptophytes were high. Increases in cyanobacterial abundance and temperature were detected in both regions. Additionally, the contribution of pico- plus nano-sized phytoplankton productivity to the total

  6. Factors affecting surf zone phytoplankton production in Southeastern North Carolina, USA

    KAUST Repository

    Cahoon, Lawrence B.

    2017-07-15

    Abstract: The biomass and productivity of primary producers in the surf zone of the ocean beach at Wrightsville Beach, North Carolina, USA, were measured during all seasons, along with environmental parameters and nutrient levels. Variation in biomass (chlorophyll a) was associated with temperature. Primary production (PP), measured by in situ 14-C incubations, was a function of chlorophyll a, tide height at the start of incubations, and rainfall in the preceding 24-hr period. Biomass-normalized production (PB) was also a function of tide height and rainfall in the preceding 24-hr period. We interpreted these results as evidence of surf production 1) as combined contributions of phytoplankton and suspended benthic microalgae, which may confound application of simple P-E models to surf zone production, and 2) being regulated by nutrient source/supply fluctuations independently from other factors. Surf zone biomass and production levels are intermediate between relatively high estuarine values and much lower coastal ocean values. Surf zone production may represent an important trophic connection between these two important ecosystems.

  7. Climate warming is predicted to reduce omega-3, long-chain, polyunsaturated fatty acid production in phytoplankton.

    Science.gov (United States)

    Hixson, Stefanie M; Arts, Michael T

    2016-08-01

    Phytoplankton are the main source of energy and omega-3 (n-3) long-chain essential fatty acids (EFA) in aquatic ecosystems. Their growth and biochemical composition are affected by surrounding environmental conditions, including temperature, which continues to increase as a result of climate warming. Increasing water temperatures may negatively impact the production of EFA by phytoplankton through the process of homeoviscous adaptation. To investigate this, we conducted an exploratory data synthesis with 952 fatty acid (FA) profiles from six major groups of marine and freshwater phytoplankton. Temperature was strongly correlated with a decrease in the proportion of n-3 long-chain polyunsaturated FA (LC-PUFA) and an increase in omega-6 FA and saturated FA. Based on linear regression models, we predict that global n-3 LC-PUFA production will be reduced by 8.2% for eicosapentaenoic acid (EPA) and 27.8% for docosahexaenoic acid (DHA) with an increase in water temperature of 2.5 °C. Using a previously published estimate of the global production of EPA by diatoms, which contribute to most of the world's supply of EPA, we predict a loss of 14.2 Mt of EPA annually as a result of ocean warming. The n-3 LC-PUFA are vitally important for an array of key physiological functions in aquatic and terrestrial organisms, and these FA are mainly produced by phytoplankton. Therefore, reduced production of these EFA, as a consequence of climate warming, is predicted to negatively affect species that depend on these compounds for optimum physiological function. Such profound changes in the biochemical composition of phytoplankton cell membranes can lead to cascading effects throughout the world's ecosystems.

  8. Spatial and seasonal variability of fractionated phytoplankton biomass and primary production in the frontal region of the Northern Adriatic Sea

    Directory of Open Access Journals (Sweden)

    M.R. VADRUCCI

    2005-06-01

    Full Text Available Spatial and seasonal patterns of variation of fractionated phytoplankton biomass and primary production and their relationships with nutrient concentrations were analyzed along an inshore - offshore gradient and in relation to the presence of a frontal system in the Northern Adriatic Sea. Sampling was carried out in winter and summer during four oceanographic cruises (June 1996 and 1997, February 1997 and 1998 as part of the PRISMA II project. Water samples for determining nutrient concentrations, phytoplankton biomass (as Chla and primary production (as 14 C assimilation were collected at five optical depths. Sampling stations were located along 2 or 4 parallel transects arranged perpendicularly to the shoreline and the frontal system. The transects were located at such a distance from the coast that the frontal system crossed them at their halfway point. Total dissolved nitrogen (TDN and total dissolved phosphorus concentrations (TDP were 12.41 ± 3 .95 mM and 0.146 ± 0 .070 mM, respectively. The values in the two seasonal periods were similar, decreasing along the inshore-offshore gradient. Values for phytoplankton biomass and primary productionwere higher in the winter than the summer cruises, and decreased, in both seasonal periods, along the inshore / offshore gradient. Moreover, in both seasonal periods, picophytoplankton dominated both biomass and productivity, (56% and 44%, respectively at stations beyond the frontal system, while microphytoplankton was more important at stations inside it (44% and 44%, respectively. Total phytoplankton biomass and primary production were directly related to nutrient concentrations. Regarding size classes, significant patterns of variation with nutrients were observed particularly for biomass. The results indicate that the size structure and function of phytoplankton guilds seem to be mediated by nutrient inflow, as well as by competitive interaction among size fractions.

  9. Effect of environmental forcing on the biomass, production and growth rate of size-fractionated phytoplankton in the central Atlantic Ocean

    Science.gov (United States)

    Huete-Ortega, María; Calvo-Díaz, Alejandra; Graña, Rocío; Mouriño-Carballido, Beatriz; Marañón, Emilio

    2011-11-01

    To ascertain the response of phytoplankton size classes to changes in environmental forcing, we determined size-fractionated biomass, carbon fixation and growth (production/biomass) rates in surface waters along the central Atlantic Ocean (26°N-5°S). As a result of the enhanced input of nutrients into the euphotic layer and the higher water column stability found at the equatorial upwelling, we observed increases not only in phytoplankton biomass and primary production, but also in turnover rates, suggesting nutrient limitation of phytoplankton physiology in the oligotrophic central Atlantic. The phytoplankton groups analysed (pico-, small nano-, large nano- and micro-phytoplankton) showed different responses to the equatorial environmental forcing, in terms of carbon biomass, primary production and growth rate. Large nano- and micro-phytoplankton consistently showed higher growth rates and carbon fixation to chl a ratios than smaller phytoplankton. We observed a higher stimulating effect of increased nitrate supply on the small phytoplankton growth rates. This observation can be explained by the dynamics of the equatorial upwelling, where the continuous but small nutrient input into the euphotic layer provide a competitive advantage for smaller cells adapted to oligotrophic conditions. The size-fractionated approach shown here reveals important group-specific differences in the response to environmental forcing, which cannot be appreciated in bulk measurements of the whole community.

  10. Cell cycle and cell signal transduction in marine phytoplankton

    Institute of Scientific and Technical Information of China (English)

    LIU Jingwen; JIAO Nianzhi; CAI Huinong

    2006-01-01

    As unicellular phytoplankton, the growth of a marine phytoplankton population results directly from the completion of a cell cycle, therefore, cell-environment communication is an important way which involves signal transduction pathways to regulate cell cycle progression and contribute to growth, metabolism and primary production and respond to their surrounding environment in marine phytoplankton. Cyclin-CDK and CaM/Ca2+ are essentially key regulators in control of cell cycle and signal transduction pathway, which has important values on both basic research and applied biotechnology. This paper reviews progress made in this research field, which involves the identification and characterization of cyclins and cell signal transduction system, cell cycle control mechanisms in marine phytoplankton cells, cell cycle proteins as a marker of a terminal event to estimate the growth rate of phytoplankton at the species level, cell cycle-dependent toxin production of toxic algae and cell cycle progression regulated by environmental factors.

  11. Connecting marine productivity to sea-spray via nanoscale biological processes: Phytoplankton Dance or Death Disco?

    Science.gov (United States)

    O'Dowd, Colin; Ceburnis, Darius; Ovadnevaite, Jurgita; Bialek, Jakub; Stengel, Dagmar B.; Zacharias, Merry; Nitschke, Udo; Connan, Solene; Rinaldi, Matteo; Fuzzi, Sandro; Decesari, Stefano; Cristina Facchini, Maria; Marullo, Salvatore; Santoleri, Rosalia; Dell'Anno, Antonio; Corinaldesi, Cinzia; Tangherlini, Michael; Danovaro, Roberto

    2015-10-01

    Bursting bubbles at the ocean-surface produce airborne salt-water spray-droplets, in turn, forming climate-cooling marine haze and cloud layers. The reflectance and ultimate cooling effect of these layers is determined by the spray’s water-uptake properties that are modified through entrainment of ocean-surface organic matter (OM) into the airborne droplets. We present new results illustrating a clear dependence of OM mass-fraction enrichment in sea spray (OMss) on both phytoplankton-biomass, determined from Chlorophyll-a (Chl-a) and Net Primary Productivity (NPP). The correlation coefficient for OMss as a function of Chl-a increased form 0.67 on a daily timescale to 0.85 on a monthly timescale. An even stronger correlation was found as a function of NPP, increasing to 0.93 on a monthly timescale. We suggest the observed dependence is through the demise of the bloom, driven by nanoscale biological processes (such as viral infections), releasing large quantities of transferable OM comprising cell debris, exudates and other colloidal materials. This OM, through aggregation processes, leads to enrichment in sea-spray, thus demonstrating an important coupling between biologically-driven plankton bloom termination, marine productivity and sea-spray modification with potentially significant climate impacts.

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

    Science.gov (United States)

    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.

  13. Heterotrophic utilization of extracellular products of phytoplankton in a tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Gomes, H.; Pant, A; Goes, J.I.; Parulekar, A

    Bacterial uptake of algal exudates has been estimated in a tropical estuary, Dona Paula, Goa, India, where the seasonal fluctuations in hydrographic and nutrient parameters as well as dissolved organic matter concentrations and phytoplankton species...

  14. The method of multispectral image processing of phytoplankton processing for environmental control of water pollution

    Science.gov (United States)

    Petruk, Vasil; Kvaternyuk, Sergii; Yasynska, Victoria; Kozachuk, Anastasia; Kotyra, Andrzej; Romaniuk, Ryszard S.; Askarova, Nursanat

    2015-12-01

    The paper presents improvement of the method of environmental monitoring of water bodies based on bioindication by phytoplankton, which identify phytoplankton particles carried out on the basis of comparison array multispectral images using Bayesian classifier of solving function based on Mahalanobis distance. It allows to evaluate objectively complex anthropogenic and technological impacts on aquatic ecosystems.

  15. Impact of ocean acidification on phytoplankton assemblage, growth, and DMS production following Fe-dust additions in the NE Pacific high-nutrient, low-chlorophyll waters

    Science.gov (United States)

    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.

  16. Interactions of anthropogenic stress factors on phytoplankton

    Directory of Open Access Journals (Sweden)

    Donat P. Häder

    2015-03-01

    Full Text Available Phytoplankton are the main primary producers in aquatic ecosystems. Their biomass production and CO2 sequestration equals that of all terrestrial plants taken together. Phytoplankton productivity is controlled by a number of environmental factors, many of which currently undergo substantial changes due to anthropogenic global climate change. Light availability is an absolute requirement for photosynthesis, but excessive visible and UV radiation impair productivity. Increasing temperatures enhance stratification, decrease the depth of the upper mixing layer exposing the cells to higher solar radiation, and reduce nutrient upward transport from deeper layers. At the same time, stratospheric ozone depletion exposes phytoplankton to higher solar UV-B radiation especially in polar and mid latitudes. Terrestrial runoff carrying sediments and dissolved organic matter into coastal waters leads to eutrophication while reducing UV penetration. All these environmental forcings are known to affect physiological and ecological processes of primary producers. Ocean acidification due to increased atmospheric CO2 concentrations changes the seawater chemistry; it reduces calcification in phytoplankton, macroalgae and many zoological taxa and enhances UV-induced damage. Ocean warming results in changing species composition and favors blooms of toxic prokaryotic and eukaryotic phytoplankton; it moderates UV-induced damage of the photosynthetic apparatus because of higher repair rates. Increasing pollution from crude oil spills, persistent organic pollutants, heavy metal as well as industrial and household wastewaters affect phytoplankton, which is augmented by solar UV radiation. In view of the fact that extensive analyses of the impacts of multiple stressors are scarce, here we review reported findings on the impacts of anthropogenic stressors on phytoplankton with an emphasis on their interactive effects and a prospect for future studies.

  17. Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

    NARCIS (Netherlands)

    Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

    2014-01-01

    Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged macrop

  18. Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

    NARCIS (Netherlands)

    Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

    2014-01-01

    Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged

  19. Carbohydrate production by phytoplankton and degradation in the marine microbial food web

    NARCIS (Netherlands)

    Alderkamp, Anne-Carlijn

    2006-01-01

    In this PhD thesis I describe studies relating to the cycling of the algal storage glucan chrysolaminaran. Chrysolaminaran is the most abundant type of storage carbohydrate in marine phytoplankton. I choose it as a model substrate to study factors influencing the cycling of carbohydrates, one of the

  20. Enhanced carbohydrate production by Southern Ocean phytoplankton in response to in situ iron fertilization

    NARCIS (Netherlands)

    van Oijen, T; Veldhuis, MJW; Gorbunov, MY; Nishioka, J; van Leeuwe, MA; de Baara, HJW; de Baar, H.J.W.

    2005-01-01

    Storage carbohydrates (e.g., water-extractable beta-1,3-D-glucan in diatoms) are of key importance for phytoplankton growth in a variable light climate, because they facilitate continued growth of the cells in darkness by providing energy and carbon skeletons for protein synthesis. Here, we tested t

  1. Carbohydrate production by phytoplankton and degradation in the marine microbial food web

    NARCIS (Netherlands)

    Alderkamp, Anne-Carlijn

    2006-01-01

    In this PhD thesis I describe studies relating to the cycling of the algal storage glucan chrysolaminaran. Chrysolaminaran is the most abundant type of storage carbohydrate in marine phytoplankton. I choose it as a model substrate to study factors influencing the cycling of carbohydrates, one of the

  2. Study of the lacustrine phytoplankton productivity dependence on solar radiation, on the basis of direct high-frequency measurements

    Science.gov (United States)

    Provenzale, Maria; Ojala, Anne; Heiskanen, Jouni; Erkkilä, Kukka-Maaria; Mammarella, Ivan; Hari, Pertti; Vesala, Timo

    2016-04-01

    One of the main components of the carbon cycle in lakes is phytoplankton. Its in situ photosynthesis and respiration are usually studied with traditional methods (dark and light bottle method, 14C labelling technique). These methods, relying on sampling and incubation, may lead to unrealistic results. They also have a poor temporal resolution, which does not allow the non-linear relationship between photosynthetically active solar radiation (PAR) and photosynthesis to be properly investigated. As a consequence, the phytoplankton net primary productivity (NPP) cannot be parameterised as a function of ambient variables. In 2008 an innovative free-water approach was proposed. It is based on non-dispersive infrared air CO2 probes that, by building an appropriate system, can be used to measure the CO2 concentration in the water at a high-frequency. At that time, the method was tested only on 3 days of data. Here, we deployed it on a boreal lake in Finland for four summers, in order to calculate the NPP and verify its dependence on PAR. The set-up was completed by an eddy-covariance system and water PAR and temperature sensors. In analogy with the procedure typically used in terrestrial ecology, we obtained the phytoplankton NPP computing the mass balance of CO2 in the mixed layer of the lake, i.e. the superficial layer where the conditions are homogeneous and most of the photosynthetic activity takes place. After calculating the NPP , we verified its dependence on PAR. The theoretical model we used was a saturating Michaelis-Menten curve, in which the variables are water temperature and PAR. The equation also contains parameters typical of the phytoplankton communities, which represent their maximum potential photosynthetic rate, their half-saturation constant and their basal respiration. These parameters allow the NPP to be parameterised as a function of T and PAR. For all the analysed year, we found a very good agreement between theory and data (R2 ranged from 0.80 to

  3. Bacterial production, primary production, phytoplankton, zooplankton, biological analysis of fish, and massive fish length data from the EVRIKA and other platforms in the Antarctic from 23 February 1980 to 09 December 1988 (NODC Accession 9600039)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bacterial production, primary production, phytoplankton, zooplankton, biological analysis of fish, and massive fish length data were collected from the EVRIKA and...

  4. MERIS Phytoplankton Time Series Products from the SW Iberian Peninsula (Sagres Using Seasonal-Trend Decomposition Based on Loess

    Directory of Open Access Journals (Sweden)

    Sónia Cristina

    2016-05-01

    Full Text Available The European Space Agency has acquired 10 years of data on the temporal and spatial distribution of phytoplankton biomass from the MEdium Resolution Imaging Spectrometer (MERIS sensor for ocean color. The phytoplankton biomass was estimated with the MERIS product Algal Pigment Index 1 (API 1. Seasonal-Trend decomposition of time series based on Loess (STL identified the temporal variability of the dynamical features in the MERIS products for water leaving reflectance (ρw(λ and API 1. The advantages of STL is that it can identify seasonal components changing over time, it is responsive to nonlinear trends, and it is robust in the presence of outliers. One of the novelties in this study is the development and the implementation of an automatic procedure, stl.fit(, that searches the best data modeling by varying the values of the smoothing parameters, and by selecting the model with the lowest error measure. This procedure was applied to 10 years of monthly time series from Sagres in the Southwestern Iberian Peninsula at three Stations, 2, 10 and 18 km from the shore. Decomposing the MERIS products into seasonal, trend and irregular components with stl.fit(, the ρw(λ indicated dominance of the seasonal and irregular components while API 1 was mainly dominated by the seasonal component, with an increasing effect from inshore to offshore. A comparison of the seasonal components between the ρw(λ and the API 1 product, showed that the variations decrease along this time period due to the changes in phytoplankton functional types. Furthermore, inter-annual seasonal variation for API 1 showed the influence of upwelling events and in which month of the year these occur at each of the three Sagres stations. The stl.fit( is a good tool for any remote sensing study of time series, particularly those addressing inter-annual variations. This procedure will be made available in R software.

  5. Biomarker reconstruction of phytoplankton productivity and community structure changes in the middle Okinawa Trough during the last 15 ka

    Institute of Scientific and Technical Information of China (English)

    XING Lei; ZHAO MeiXun; ZHANG HaiLong; LIU YanGuang; SHI XueFa

    2008-01-01

    Biomarkers have been widely used to reconstruct phytoplankton productivity and community structure changes,and this method has been applied for the first time in the middle Okinawa Trough during the transition from the last deglaciation to the Holocene.The total content of all marine phytoplankton biomarkers,used as a total productivity indicator,reveals higher productivity during the deglaciation.The ratios of the biomarkers are used as community structure indicators which show that,compared with the Holocene,the contribution from haptophytes decreased while the contributions from diatoms and dinoflagellates increased during the deglaciation.The increased productivity during the deglacia-tion was likely caused by the stronger winter monsoon.Also increased nutrient supply from terrestrial sources contributes to the higher productivity due to lower sea-level,which is consistent with higher terrestrial biomarker (long-chain n-alkanols) content.These changes in the nutrient supply also con-tributed to the community structure changes in the Okinawa Trough.

  6. Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

    Science.gov (United States)

    Kaufman, Daniel E.; Friedrichs, Marjorie A. M.; Smith, Walker O.; Hofmann, Eileen E.; Dinniman, Michael S.; Hemmings, John C. P.

    2017-03-01

    The Ross Sea, a highly productive region of the Southern Ocean, is expected to experience warming during the next century along with reduced summer sea ice concentrations and shallower mixed layers. This study investigates how these climatic changes may alter phytoplankton assemblage composition, primary productivity, and export. Glider measurements are used to force a one-dimensional biogeochemical model, which includes diatoms and both solitary and colonial forms of Phaeocystis antarctica. Model performance is evaluated with glider observations, and experiments are conducted using projections of physical drivers for mid-21st and late-21st century. These scenarios reveal a 5% increase in primary productivity by midcentury and 14% by late-century and a proportional increase in carbon export, which remains approximately 18% of primary production. In addition, scenario results indicate diatom biomass increases while P. antarctica biomass decreases in the first half of the 21st century. In the second half of the century, diatom biomass remains relatively constant and P. antarctica biomass increases. Additional scenarios examining the independent contributions of expected future changes (temperature, mixed layer depth, irradiance, and surface iron inputs from melting ice) demonstrate that earlier availability of low light due to reduction of sea ice early in the growing season is the primary driver of productivity increases over the next century; shallower mixed layer depths additionally contribute to changes of assemblage composition and export. This study further demonstrates how glider data can be effectively used to facilitate model development and simulation, and inform interpretation of biogeochemical observations in the context of climate change.Plain Language SummaryUnderstanding how the global ocean responds to climate change requires knowing the natural behavior of individual regions and anticipating how future changes will affect each region differently. It

  7. Controls on marine carbon fluxes via phytoplankton-microzooplankton interactions in continental shelf waters. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1994-05-01

    The project is an in-depth evaluation of the phytoplankton-microzooplankton trophic link. The principal goals of the project remain as originally proposed: (1) Impact of grazing by phagotrophic microzooplankton on phytoplankton, particularly on phototrophic cells <5 {mu}m in size, which are not effectively grazed by macrozooplankton. (2) Impact of grazing by phagotrophic microzooplankton on bacterioplankton. (3) Taxon-specific growth rates of phytoplankton in situ, particularly of <5 {mu}m sized cells, as they are affected by phagotrophy rates. The authors are developing protocols for making quantitative estimates of grazing by phagotrophic protists on ultraphytoplankton, and for determining the intrinsic reproductive rates of phytoplankton species. They have also begun a series of experiments, testing and utilizing these methods, evaluating the grazing impact of flagellates and ciliates on phytoplankton species of different sizes and taxonomic affinities. A series of preliminary experiments in coastal waters adjacent to the Oregon Institute of Marine Biology have provided a coastal benchmark. They participated in a preliminary cruise in May, 1993 to the OMP field site off Cape Hatteras. Their purpose was to obtain background information on heterotrophic microbial distributional patterns in this region and to measure rates of protist bacterivory.

  8. Photosynthetic parameters and primary production, with focus on large phytoplankton, in a temperate mid-shelf ecosystem

    KAUST Repository

    Moran, Xose Anxelu G.

    2015-01-09

    Annual variability of photosynthetic parameters and primary production (PP), with a special focus on large (i.e. >2μm) phytoplankton was assessed by monthly photosynthesis-irradiance experiments at two depths of the southern Bay of Biscay continental shelf in 2003. Integrated chl a (22-198mgm-2) was moderately dominated by large cells on an annual basis. The March through May dominance of diatoms was replaced by similar shares of dinoflagellates and other flagellates during the rest of the year. Variability of photosynthetic parameters was similar for total and large phytoplankton, but stratification affected the initial slope αB [0.004-0.049mgCmg chl a-1h-1 (μmol photons m-2s-1)-1] and maximum photosynthetic rates PmB (0.1-10.7mgCmg chl a-1h-1) differently. PmB, correlated positively with αB only for the large fraction. PmB tended to respond faster to ambient irradiance than αB, which was negatively correlated with diatom abundance in the >2μm fraction. Integrated PP rates were relatively low, averaging 387 (132-892) for the total and 207 (86-629) mg C m-2d-1 for the large fraction, probably the result of inorganic nutrient limitation. Although similar mean annual contributions of large phytoplankton to total values were found for biomass and PP (~58%), water-column production to biomass ratios (2-26mgCmg chl-1d-1) and light utilization efficiency of the >2μm fraction (0.09-0.84gCg chl-1mol photons-1m2) were minimum during the spring bloom. Our results indicate that PP peaks in the area are not necessarily associated to maximum standing stocks.

  9. Comment on "Does the fall phytoplankton blooom control recruitment of Georges Bank, haddock, Melanogrammus aeglefinus, through parental condition?"

    DEFF Research Database (Denmark)

    Payne, Mark; Dickey-Collas, Mark; Nash, Richard D.M.

    2009-01-01

    In the paper "Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus, through parental condition?", Friedland et al. (Can. J. Fish. Aquat. Sci. 65(6): 1076-1086, 2008) examine a sizable number of hypotheses aiming to explain the recruitment patterns...... observed in Georges Bank haddock. The authors focus on a correlation between the size of the autumnal phytoplankton bloom and the survivor ratio (recruitment), concluding this to be the main factor determining recruitment, via the mechanism of adult condition at the time of spawning. Here we examine....... disregard correlations that are, in fact, significant. Furthermore, we show that the parental condition hypothesis hinges upon a single, highly uncertain data point, without which the correlation is no longer significant. We find that evidence for the parental condition hypothesis is weak...

  10. Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters

    CSIR Research Space (South Africa)

    Thomalla, J

    2010-01-01

    Full Text Available . The results from this study favour Si limitation, light-limited deep mixing and likely Fe deficiency as the dominant mechanisms controlling significant new production by micro-phytoplankton. Increased concentrations of micro-phytoplankton cells and and rates...

  11. Diagnosis of Physical and Biological Control over Phytoplankton in the Gulf of Maine-Georges Bank Region Using an Adjoint Data Assimilation Approach

    Institute of Scientific and Technical Information of China (English)

    WANG Caixia; Paola Malanotte-Rizzoli

    2014-01-01

    The linkage between physical and biological processes, particularly the effect of the circulation field on the distribution of phytoplankton, is studied by applying a two-dimensional model and an adjoint data assimilation approach to the Gulf of Maine-Georges Bank region. The model results, comparing well with observation data, reveal seasonal and geographic variations of phytoplankton concentration and verify that the seasonal cycles of phytoplankton are controlled by both biological sources and ad-vection processes which are functions of space and time and counterbalance each other. Although advective flux divergences have greater magnitudes on Georges Bank than in the coastal region of the western Gulf of Maine, advection control over phytoplankton concentration is more significant in the coastal region of the western Gulf of Maine. The model results also suggest that the two separated populations in the coastal regions of the western Gulf of Maine and on Georges Bank are self-sustaining.

  12. Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon.

    Science.gov (United States)

    Deininger, A; Faithfull, C-L; Bergström, A-K

    2017-01-31

    Global change has increased inorganic nitrogen (N) and dissolved organic carbon (DOC; i.e. 'browning') inputs to northern hemisphere boreal lakes. However, we do not know how phytoplankton in nutrient poor lake ecosystems of different DOC concentration respond to increased N availability. Here, we monitored changes in phytoplankton production, biomass and community composition in response to whole lake inorganic N fertilization in six boreal unproductive Swedish lakes divided into three lake pairs (control, N enriched) at three DOC levels (low, medium, high), with one reference year (2011) and two impact years (2012, 2013). We found that phytoplankton biomass and production decreased with DOC concentration before N fertilization. Further, phytoplankton community composition also differed with respect to DOC, with a dominance of non-flagellated autotrophs at low DOC towards an increasing dominance of flagellated autotrophs with increased lake DOC concentration. The N fertilization increased phytoplankton biomass and production in all lakes, but did not affect phytoplankton community composition. However, the net response in biomass and production to N fertilization declined with increasing DOC, implying that the lake DOC concentration is critical in order to infer phytoplankton responses to N fertilization, and that the system switches from being primarily nutrient limited to becoming increasingly light limited with increased DOC concentration. In conclusion, our results show that browning will reduce phytoplankton production and biomass and influence phytoplankton community composition, whereas increased inorganic N loadings from deposition, forestry or other land use will primarily enhance phytoplankton biomass and production. Together, any change in the landscape that enhances inorganic N availability will increase phytoplankton production and biomass, but the positive effects of N will be much weaker or even neutralized in browner lakes as caused by light

  13. Spring phytoplankton in the eastern coastal Gulf of Alaska: Photosynthesis and production during high and low bloom years

    Science.gov (United States)

    Strom, Suzanne L.; Fredrickson, Kerri A.; Bright, Kelley J.

    2016-10-01

    Primary production associated with the spring bloom in high-latitude seas constitutes a substantial fraction of annual total in those environments, and provides a seasonally timed bounty to benthic and pelagic organisms at higher trophic levels. Light is widely believed to regulate the timing and magnitude of spring production in the coastal Gulf of Alaska, although few data are available on the relationship between light and photosynthesis or primary production in that region. In two cruises to the coastal waters of southeast Alaska (May 2011 and April 2013), we observed strongly contrasting early-season phytoplankton communities, although environmental conditions were largely similar. An early, diatom-dominated spring bloom occurred in April 2013, while the anomalously low chlorophyll conditions of spring 2011 were widely observed in May of that year. Integrated chlorophyll a (Chl) was substantially higher in April 2013 than in May 2011 (median 62 versus 29 mg m-2), and April 2013 saw a greater contribution by large cells (>20 μm size fraction) to total Chl. The rate (0.18 versus 0.65 d-1), and a greater biomass of picophytoplankton (cells ≤2 μm) in 2011. Photosynthesis-irradiance experiments in both years revealed low light-acclimated spring communities, with high photosynthetic efficiencies (αB) and low irradiances for the onset of light saturation, contrasting strongly with the high light-acclimated summer Gulf of Alaska community previously described. Photoinhibition was seen in both springs but was more frequent and severe in the small cell-dominated community of 2011. Maximum photosynthetic rates (PMB) were higher in the high-Chl month of April 2013 than in May 2011, averaging 5.3 versus 3.4 μg C μg Chl-1 h-1 across all depths and both size classes. In May 2011, PMB showed a strong negative correlation with salinity, while several photosynthetic parameters were correlated to light exposure history. In contrast, we found no environmental correlates to

  14. Spatio-temporal variability of the phytoplankton biomass in the Levantine basin between 2002 and 2015 using MODIS products

    Directory of Open Access Journals (Sweden)

    Roy El Hourany

    2017-04-01

    Full Text Available The Levantine basin in the Eastern Mediterranean Sea is subject to spatial and seasonal variations in primary production and physical-chemical properties both on a short and long-term basis. In this study, the monthly means of daily MODIS product images were averaged between 2002 and 2015, and used to characterize the phytoplankton blooms in different bioregions of the Levantine basin. The selected products were the sea surface temperature (SST, the chlorophyll-a concentration (Chl-a, the diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490 and the colored dissolved organic matter index (CDOM_index. Our results showed that phytoplankton blooms were spatially and temporally variable. They occurred in late autumn at the Nile Delta, in early spring and late summer at the eastern coastline, and in spring at the northeastern coastline. The northern coastline and the open water had a common bloom occurring in winter. The Nile Delta was found to be the most productive area of the Levantine basin showing high Chl-a. Kd_490 and Chl-a present a parallel co-variation indicating a dominance of Case 1 waters in the Levantine basin. The CDOM_index shows a phase shift with the Chl-a fluctuation. A strong inverse correlation was observed between both Chl-a and CDOM_index with SST, connoting an indirect relation represented by a depression of CDOM in summer by photobleaching, and a suppression of the chlorophyll-a concentration due to water stratification, together with nutrient stress. An overestimation of the Chl-a values had been signaled by the use of the CDOM_index, suggesting a correction plan in a latter study.

  15. Directional and Spectral Irradiance in Ocean Models:Effects on Simulated Global Phytoplankton,Nutrients,and Primary Production

    Directory of Open Access Journals (Sweden)

    Watson Gregg

    2016-11-01

    Full Text Available The importance of including directional and spectral light in simulations of ocean radiative transfer was investigated using a coupled biogeochemical-circulation-radiative model of the global oceans. The effort focused on phytoplankton abundances, nutrient concentrations and net primary production.The importance was approached by sequentially removing directional (i.e., direct vs. diffuse and spectral irradiance and comparing results of the above variables to a fully directionally and spectrally-resolved model.In each case the total irradiance was kept constant; it was only the pathways and spectral nature that were changed.Assuming all irradiance was diffuse had negligible effect on global ocean primary production. Global nitrate and total chlorophyll concentrations declined by about 20% each. The largest changes occurred in the tropics and sub-tropics rather than the high latitudes, where most of the irradiance is already diffuse. Disregarding spectral irradiance had effects that depended upon the choice of attenuation wavelength. The wavelength closest to the spectrally-resolved model, 500nm, produced lower nitrate (19% and chlorophyll (8% and higher primary production (2% than the spectral model. Phytoplankton relative abundances were very sensitive to the choice of non-spectral wavelength transmittance. The combined effects of neglecting both directional and spectral irradiance exacerbated the differences, despite using attenuation at 500nm. Global nitrate decreased 33% and chlorophyll decreased 24%. Changes in phytoplankton community structure were considerable, representing a change from chlorophytes to cyanobacteria and coccolithophores. This suggested a shift in community function, from light-limitation to nutrient limitation: lower demands for nutrients from cyanobacteria and coccolithophores favored them over the more nutrient-demanding chlorophytes. Although diatoms have the highest nutrient demands in the model, their relative

  16. Seasonal changes in temperature and nutrient control of photosynthesis, respiration and growth of natural phytoplankton communities

    DEFF Research Database (Denmark)

    Stæhr, P. A.; Sand-Jensen, K.

    2006-01-01

    1. To investigate the influence of elevated temperatures and nutrients on photosynthesis, respiration and growth of natural phytoplankton assemblages, water was collected from a eutrophic lake in spring, summer, autumn, winter and the following spring and exposed to ambient temperature and ambient...... +2, +4 and +6 °C for 2 weeks with and without addition of extra inorganic nutrients. 2. Rates of photosynthesis, respiration and growth generally increased with temperature, but this effect was strongly enhanced by high nutrient availability, and therefore was most evident for nutrient amended....... 4. Although we found distinct responses to relatively small temperature increases, the interaction between nutrient availability, time of the year and, thus, ambient temperature was responsible for most of the observed variability in phytoplankton growth, photosynthesis and respiration. 5. Although...

  17. Ammonium production off central Chile (36°S by photodegradation of phytoplankton-derived and marine dissolved organic matter.

    Directory of Open Access Journals (Sweden)

    Angel Rain-Franco

    Full Text Available We investigated the production of ammonium by the photodegradation of dissolved organic matter (DOM in the coastal upwelling system off central Chile (36°S. The mean penetration of solar radiation (Z1% between April 2011 and February 2012 was 9.4 m, 4.4 m and 3.2 m for Photosynthetically Active Radiation (PAR; 400-700 nm, UV-A (320-400 nm and UV-B (280-320 nm, respectively. Ammonium photoproduction experiments were carried out using exudates of DOM obtained from cultured diatom species (Chaetoceros muelleri and Thalassiosira minuscule as well as natural marine DOM. Diatom exudates showed net photoproduction of ammonium under exposure to UVR with a mean rate of 0.56±0.4 µmol L(-1 h(-1 and a maximum rate of 1.49 µmol L(-1 h(-1. Results from natural marine DOM showed net photoproduction of ammonium under exposure to PAR+UVR ranging between 0.06 and 0.2 µmol L(-1 h(-1. We estimated the potential contribution of photochemical ammonium production for phytoplankton ammonium demand. Photoammonification of diatom exudates could support between 117 and 453% of spring-summer NH4(+ assimilation, while rates obtained from natural samples could contribute to 50-178% of spring-summer phytoplankton NH4(+ requirements. These results have implications for local N budgets, as photochemical ammonium production can occur year-round in the first meters of the euphotic zone that are impacted by full sunlight.

  18. Biophysical interactions control the size and abundance of large phytoplankton chains at the Ushant tidal front.

    Directory of Open Access Journals (Sweden)

    José M Landeira

    Full Text Available Phytoplankton blooms are usually dominated by chain-forming diatom species that can alter food pathways from primary producers to predators by reducing the interactions between intermediate trophic levels. The food-web modifications are determined by the length of the chains; however, the estimation is biased because traditional sampling strategies damage the chains and, therefore, change the phytoplankton size structure. Sedimentological studies around oceanic fronts have shown high concentrations of giant diatom mats (>1 cm in length, suggesting that the size of diatom chains is underestimated in the pelagic realm. Here, we investigate the variability in size and abundance of phytoplankton chains at the Ushant tidal front (NW France using the Video Fluorescence Analyzer (VFA, a novel and non-invasive system. CTD and Scanfish profiling characterized a strong temperature and chlorophyll front, separating mixed coastal waters from the oceanic-stratified domain. In order to elucidate spring-neap variations in the front, vertical microstructure profiler was used to estimate the turbulence and vertical nitrate flux. Key findings were: (1 the VFA system recorded large diatom chains up to 10.7 mm in length; (2 chains were mainly distributed in the frontal region, with maximum values above the pycnocline in coincidence with the maximum chlorophyll; (3 the diapycnal fluxes of nitrate enabled the maintenance of the bloom in the frontal area throughout the spring-neap tidal cycle; (4 from spring to neap tide the chains length was significantly reduced; (5 during neap tide, the less intense vertical diffusion of nutrients, as well as the lower turbulence around the chains, intensified nutrient-depleted conditions and, thus, very large chains became disadvantageous. To explain this pattern, we suggest that size plasticity is an important ecological trait driving phytoplankton species competition. Although this plasticity behavior is well known from

  19. Nitrogen and carbon limitation of planktonic primary production and phytoplankton-bacterioplankton coupling in ponds on the McMurdo Ice Shelf, Antarctica

    DEFF Research Database (Denmark)

    Sorrell, B.K.; Hawes, I.; Safi, K.

    2013-01-01

    The nature of nutrient limitation and coupling of planktonic primary and secondary production were investigated in meltwater ponds of the Ross Ice Shelf, Antarctica, using regression tree analysis and multiple regression. Phytoplankton were primaril N-limited but inorganic carbon apparently co...

  20. Glacial meltwater influences on plankton community structure and the importance of top-down control (of primary production) in a NE Greenland fjord

    DEFF Research Database (Denmark)

    Arendt, Kristine Engel; Agersted, Mette Dalgaard; Sejr, Mikael Kristian

    2016-01-01

    , and their grazing impact was the highest among the copepod groups. Copepod grazing impact on the phytoplankton standing stock, however, was exceeded by microzooplankton grazing, investigated by dilution experiments, with the highest grazing impact on the phytoplankton standing stock of 63% d−1 in the inner part...... of the fjord. In spite of high phytoplankton instantaneous growth rates at the innermost fjord station, proto-zooplankton was capable of controlling the phytoplankton production. The study showed functional differences within the system and provides indications of how dynamic the coastal ecosystem of Greenland...

  1. Effects of the pH/pCO2 control method in the growth medium of phytoplankton

    Directory of Open Access Journals (Sweden)

    F. M. M. Morel

    2009-02-01

    Full Text Available To study the effects of ocean acidification on the physiology of phytoplankton requires that the key chemical parameters of the growth medium, pCO2, pH and Ω (the saturation state of calcium carbonate be carefully controlled. This is made difficult by the interdependence of these parameters. Moreover, in growing batch cultures of phytoplankton, the fixation of CO2, the uptake of nutrients and, for coccolithophores, the precipitation of calcite all change the inorganic carbon and acid-base chemistry of the medium. For example, absent pH-buffering or CO2 bubbling, a sizeable decrease in pCO2 occurs at a biomass concentration as low as 50 μM C in non-calcifying cultures. Even in cultures where pCO2 or pH is maintained constant, other chemical parameters change substantially at high cell densities. The quantification of these changes is facilitated by the use of buffer capacities. Experimentally we observe that all methods of adjustment of pCO2/pH can be used, the choice of one or the other depending on the specifics of the experiments. The mechanical effect of bubbling of cultures seems to induce more variable results than other methods of pCO2/pH control. While highly convenient, the addition of pH buffers to the medium induces changes in trace metal availability and cannot be used under trace metal-limiting conditions.

  2. Late holocene trends of phytoplankton productivity and anoxia as inferred from diatom and geochemical proxies in Lake Victoria, Eastern Africa

    Science.gov (United States)

    Andama, M.; Lejju, J. B.; Tolo, C. U.

    2013-11-01

    Lake Victoria ecosystem has undergone major ecological changes in the recent decades. Sedimentary diatom analysis and Fe / Mn determined by Energy Dispersive X-ray Fluorescence (EDXRF) have provided phytoplankton (diatom) productivity and the resultant anoxia (Fe / Mn) in Lake Victoria at Napoleon Gulf during the late Holocene (1778 cal yr BP (calibrated years before present) to 2008 AD) with radiocarbon dates determined using Accelerator Mass Spectrometry standard method. The results showed that increased total diatom counts in Napoleon Gulf during the late Holocene correspond with increased Fe / Mn ratio (anoxia) in some of the profiles and not in others and in most cases those that correspond correlate very well with increased eutrophication from nitrate input (Total Nitrogen, TN). Therefore slightly increased anoxia not related to increased diatom productivity was recorded in Lake Victoria at Napoleon Gulf from the period 1778 to 1135 cal yr BP. There was slightly increased diatom productivity at Napoleon Gulf from the period 857 to 758 cal yr BP but it did not increase anoxia in the lake. The period 415 cal yr BP to 2008 AD recorded increased anoxia at Napoleon Gulf related to high diatom productivity especially from 415 to 390 cal yr BP and 191 cal yr BP to 2008 AD.

  3. Phytoplankton abundance and community structure in the Antarctic polar frontal region during austral summer of 2009

    Institute of Scientific and Technical Information of China (English)

    SHRAMIK Patil; RAHUL Mohan; SUHAS Shetye; SAHINA Gazi

    2013-01-01

    The Antarctic polar front region in the Southern Ocean is known to be most productive.We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February,2009) onboard R/V Akademic Boris Petrov.We used the phytoplankton and microheterotrophs abundance,as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region.This study emphasizes the shift of phytoplankton,from large (>10 μm) to small (<10 μm) size.The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure.This probably reduces small (<10 μm) and large (>10 μm)phytoplankton abundance during the late austral summer.This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance,due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.

  4. Global Ocean Phytoplankton

    Science.gov (United States)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2014-01-01

    Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.

  5. Upwelling and anthropogenic forcing on phytoplankton productivity and community structure changes in the Zhejiang coastal area over the last 100 years

    Institute of Scientific and Technical Information of China (English)

    DUAN Shanshan; XING Lei; ZHANG Hailong; FENG Xuwen; YANG Haili; ZHAO Meixun

    2014-01-01

    Phytoplankton productivity and community structure in marginal seas have been altered significantly dur-ing the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores (#34:28.5°N, 122.272°E;CJ12-1269:28.861 9°N, 122.515 3°E) from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970s and increased rapidly after the late 1990s at Site #34;and it started to increase gradually from the middle 1960s and increased rapidly after the late 1980s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phy-toplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B (dinosterol/brassicasterol) ratio of Core #34 since the 1960s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950s indicated in-creased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950-1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.

  6. Factors controlling phytoplankton ice-edge blooms in the marginal ice-zone of the northwestern Weddell Sea during sea ice retreat 1988 : field observations and mathematical modelling

    NARCIS (Netherlands)

    Lancelot, Christiane; Mathot, Sylvie; Veth, Cornelis; Baar, Hein de

    1993-01-01

    The factors controlling phytoplankton bloom development in the marginal ice zone of the northwestern Weddell Sea were investigated during the EPOS (Leg 2) expedition (1988). Measurements were made of physical and chemical processes and biological activities associated with the process of ice-melting

  7. Factors controlling phytoplankton ice-edge blooms in the marginal ice-zone of the northwestern Weddell Sea during sea ice retreat 1988 : field observations and mathematical modelling

    NARCIS (Netherlands)

    Lancelot, Christiane; Mathot, Sylvie; Veth, Cornelis; Baar, Hein de

    1993-01-01

    The factors controlling phytoplankton bloom development in the marginal ice zone of the northwestern Weddell Sea were investigated during the EPOS (Leg 2) expedition (1988). Measurements were made of physical and chemical processes and biological activities associated with the process of ice-melting

  8. Copepod grazing and their impact on phytoplankton standing stock and production in a tropical coastal water during the different seasons

    Digital Repository Service at National Institute of Oceanography (India)

    Jagadeesan, L.; Jyothibabu, R.; Arunpandi, N.; Parthasarathi, S.

    structure (Bautista and Harris 1992; Lee et al. 2012). Calanoid copepods showed both positive electivity on micro and nano plankton fractions (Fig.4) during low phytoplankton standing stock periods (Pre-Monsoon and Post-Monsoon), whereas they showed... on phytoplankton biomass are variable, ranging from <10% to 30% to standing stock (Morales et al. 1991; Bautista and Harris 1992; Dagg 1995; Froneman 2000; Grunewald et al. 2002; Li et al. 2003; Kibirige and Perisinotto 2003). Copepods normally consumed <30...

  9. Measurement of water column primary production using photosynthesis-irradiance relations for surface phytoplankton, the vertical chlorophyll profile, and underwater light intensity

    Science.gov (United States)

    Demidov, A. B.; Gagarin, V. I.; Mosharov, S. A.

    2016-09-01

    A method has been developed to measure water column integrated primary production (PPint) in the water column using photosynthesis-irradiance relations for surface phytoplankton, the vertical profile of chlorophyll a concentration, and the underwater light intensity. Good correlation has been found for the results calculated with this method and light dependences in situ. The advantages of this method are the independence of PPint calculation from CTD profiling and water sampling, and thus optimization (reduction) of the station working time.

  10. Silicon limitation on primary production and its destiny in Jiaozhou Bay, China Ⅷ: The variation of atmospheric carbon caused by both phytoplankton and human

    Institute of Scientific and Technical Information of China (English)

    杨东方; 苗振清; 石强; 陈豫; 陈国光

    2010-01-01

    Statistical analysis on data collected in the Jiaozhou Bay (Shandong, China) from May 1991 to February 1994 and those collected in Hawaii from March 1958 to December 2007 shows dynamic and cyclic changes in atmospheric carbon in the Northern Pacific Ocean (NPO), as well as the variation in space-time distribution of phytoplankton primary production and atmospheric carbon in the study regions. The study indicates that the human beings have imposed an important impact on the changing trends of the atmospheric...

  11. Saccharides enhance iron bioavailability to Southern Ocean phytoplankton

    NARCIS (Netherlands)

    Hassler, C.S.; Schoemann, V.; Nichols, C.M.; Butler, E.C.V.; Boyd, P.W.; Nichols, C.M.

    2011-01-01

    Iron limits primary productivity in vast regions of the ocean. Given that marine phytoplankton contribute up to 40% of global biological carbon fixation, it is important to understand what parameters control the availability of iron (iron bioavailability) to these organisms. Most studies on iron bio

  12. A 150-year record of phytoplankton community succession controlled by hydroclimatic variability in a tropical lake

    Science.gov (United States)

    Afrifa Yamoah, Kweku; Callac, Nolwenn; Fru, Ernest Chi; Wohlfarth, Barbara; Wiech, Alan; Chabangborn, Akkaneewut; Smittenberg, Rienk H.

    2016-07-01

    Climate and human-induced environmental change promote biological regime shifts between alternate stable states, with implications for ecosystem resilience, function, and services. While these effects have been shown for present-day ecosystems, the long-term response of microbial communities has not been investigated in detail. This study assessed the decadal variations in phytoplankton communities in a ca. 150 year long sedimentary archive of Lake Nong Thale Prong (NTP), southern Thailand using a combination of bulk geochemical analysis, quantitative polymerase chain reaction (qPCR) and lipid biomarkers techniques including compound-specific hydrogen isotope analysis as a proxy for precipitation. Relatively drier and by inference warmer conditions from ca. 1857 to 1916 Common Era (CE) coincided with a dominance of the green algae Botryococcus braunii, indicating lower nutrient levels in the oxic lake surface waters, possibly related to lake water stratification. A change to higher silica (Si) input around 1916 CE was linked to increased rainfall and concurs with an abrupt takeover by diatom blooms lasting for 50 years. These were increasingly outcompeted by cyanobacteria from the 1970s onwards, most likely because of increased levels of anthropogenic phosphate and a reduction in rainfall. Our results showcase that the multi-proxy approach applied here provides an efficient way to track centennial-scale limnological, geochemical and microbial change, as influenced by hydroclimatic and anthropogenic forcing.

  13. Phytoplankton production and chlorophyll distribution in the eastarn and central Arabian Sea in 1994-1995

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattathiri, P.M.A.; Pant, A.; Sawant, S.S.; Gauns, M.; Matondkar, S.G.P.; Mahanraju, R.

    Measurements of primary production, chlorophyll a, particulate organic carbon (POC) and nitrogen (PON) were carried out during the inter-monsoon winter monsoon and summer monsoon seasons of 1994-95 in the central and eastern Arabian Sea...

  14. Biological production, export efficiency, and phytoplankton communities across 8000 km of the South Atlantic

    Science.gov (United States)

    Howard, E. M.; Durkin, C. A.; Hennon, G. M. M.; Ribalet, F.; Stanley, R. H. R.

    2017-07-01

    In situ oxygen tracers (triple oxygen isotope and oxygen/argon ratios) were used to evaluate meridional trends in surface biological production and export efficiency across 8000 km of the tropical and subtropical South Atlantic in March-May 2013. We used observations of picophytoplankton, nanophytoplankton, and microphytoplankton to evaluate community structure and diversity and assessed the relationships of these characteristics with production, export efficiency, and particulate organic carbon (POC) fluxes. Rates of productivity were relatively uniform along most of the transect with net community production (NCP) between 0 and 10 mmol O2 m-2 d-1, gross primary production (GPP) between 40 and 100 mmol O2 m-2 d-1, and NCP/GPP, a measure of export efficiency, ranging from 0.1 to 0.2 (0.05-0.1 in carbon units). However, notable exceptions to this basin-scale homogeneity included two locations with highly enhanced NCP and export efficiency compared to surrounding regions. Export of POC and particulate nitrogen, derived from sediment traps, correlated with GPP across the transect, over which the surface community was dominated numerically by picophytoplankton. NCP, however, did not correlate with POC flux; the mean difference between NCP and POC flux was similar to published estimates of dissolved organic carbon export from the surface ocean. The interrelated rates of production presented in this work contribute to the understanding, building on the framework of better-studied ocean basins, of how carbon is biologically transported between the atmosphere and the deep ocean.

  15. Importance of wind and river discharge in influencing nutrient dynamics and phytoplankton production in summer in the central Strait of Georgia

    DEFF Research Database (Denmark)

    Yin, K.D.; Goldblatt, R.H.; Harrison, P.J.;

    1997-01-01

    profiles of salinity, temperature, fluorescence and nutrients (nitrate and phosphate) were taken daily along a transect. A wind event occurred on August 7 and a rapid increase in the Fraser River discharge took place from August 8 to 14. The wind event mixed the water column and nutrients increased...... at the same time. Phytoplankton responded to the increase in nutrients and a bloom occurred soon after the wind event. The rapid increase in river discharge caused the entrainment of nitrate in the estuarine plume and, as a result, a subsurface maximum of chi a was developed. Our results clearly demonstrated...... that summer phytoplankton productivity in the central Strait of Georgia is fueled by a supply of nutrients from the nitracline through vertical mixing induced by the interaction of winds, river discharge and tidal cycles. Of these 3 factors, winds are the most variable and therefore a summer with frequent...

  16. Shipboard measurements of phytoplankton production and solar-stimulated fluorescence rates in the northwest Atlantic

    Science.gov (United States)

    Stegmann, P. M.; Lewis, M. R.

    1997-06-01

    We present results from a cruise to the Canadian sub-arctic and the Scotian Shelf designed to evaluate optical methods for bio-optical estimation of primary productivity. Vertical profiles of temperature and chlorophyll showed much variability from one station to the next, while primary production (normalized to biomass) ranged from 0.4 to 1 gC gChl -1 h -1 near the surface and decreased with depth. We used the linear model of Stegmann et al. (1992) (in Journal of Geophysical Research97, 627-638) to examine the relationship between solar-stimulated fluorescence and primary production and to determine the variability of the ratio of the quantum yield of photosynthesis, Φ c to the quantum yield of fluorescence, Φ f. We found that (1) there was a clear relation between production and fluorescence; (2) diurnal variations contributed to the variability in and (3) ranged from 0.32 to 0.42 molC Ein -1. The range of Φ found in this study is similar to the one from the equatorial Pacific (Stegmann et al., 1992, in Journal of Geophysical Research97, 627-638), despite the fact that the environmental conditions in the two regions were very different from each other. We did not find an increase in Φ c Φ as temperature increased.

  17. Net production and consumption of fluorescent colored dissolved organic matter by natural bacterial assemblages growing on marine phytoplankton exudates.

    Science.gov (United States)

    Romera-Castillo, Cristina; Sarmento, Hugo; Alvarez-Salgado, Xosé Antón; Gasol, Josep M; Marrasé, Celia

    2011-11-01

    An understanding of the distribution of colored dissolved organic matter (CDOM) in the oceans and its role in the global carbon cycle requires a better knowledge of the colored materials produced and consumed by marine phytoplankton and bacteria. In this work, we examined the net uptake and release of CDOM by a natural bacterial community growing on DOM derived from four phytoplankton species cultured under axenic conditions. Fluorescent humic-like substances exuded by phytoplankton (excitation/emission [Ex/Em] wavelength, 310 nm/392 nm; Coble's peak M) were utilized by bacteria in different proportions depending on the phytoplankton species of origin. Furthermore, bacteria produced humic-like substances that fluoresce at an Ex/Em wavelength of 340 nm/440 nm (Coble's peak C). Differences were also observed in the Ex/Em wavelengths of the protein-like materials (Coble's peak T) produced by phytoplankton and bacteria. The induced fluorescent emission of CDOM produced by prokaryotes was an order of magnitude higher than that of CDOM produced by eukaryotes. We have also examined the final compositions of the bacterial communities growing on the exudates, which differed markedly depending on the phytoplankton species of origin. Alteromonas and Roseobacter were dominant during all the incubations on Chaetoceros sp. and Prorocentrum minimum exudates, respectively. Alteromonas was the dominant group growing on Skeletonema costatum exudates during the exponential growth phase, but it was replaced by Roseobacter afterwards. On Micromonas pusilla exudates, Roseobacter was replaced by Bacteroidetes after the exponential growth phase. Our work shows that fluorescence excitation-emission matrices of CDOM can be a helpful tool for the identification of microbial sources of DOM in the marine environment, but further studies are necessary to explore the association of particular bacterial groups with specific fluorophores.

  18. Factors controlling phytoplankton ice-edge blooms in the marginal ice-zone of the northwestern Weddell Sea during sea ice retreat 1988: field observations and mathematical modelling

    OpenAIRE

    Lancelot, Christiane; Mathot, Sylvie; Veth, Cornelis; de Baar, Hein

    1993-01-01

    The factors controlling phytoplankton bloom development in the marginal ice zone of the northwestern Weddell Sea were investigated during the EPOS (Leg 2) expedition (1988). Measurements were made of physical and chemical processes and biological activities associated with the process of ice-melting and their controlling variables particularly light limitation mediated by vertical stability and ice-cover, trace metal deficiency and grazing pressure. The combined observations and process studi...

  19. Impact of atmospheric nitrogen deposition on phytoplankton productivity in the South China Sea

    Science.gov (United States)

    Kim, Tae-Wook; Lee, Kitack; Duce, Robert; Liss, Peter

    2014-05-01

    The impacts of anthropogenic nitrogen (N) deposition on the marine N cycle are only now being revealed, but the magnitudes of those impacts are largely unknown in time and space. The South China Sea (SCS) is particularly subject to high anthropogenic N deposition, because the adjacent countries are highly populated and have rapidly growing economies. Analysis of data sets for atmospheric N deposition, satellite chlorophyll-a (Chl-a), and air mass back trajectories reveals that the transport of N originating from the populated east coasts of China and Indonesia, and its deposition to the ocean, has been responsible for the enhancements of Chl-a in the SCS. We found that atmospheric N deposition contributed approximately 20% of the annual biological new production in the SCS. The airborne contribution of N to new production in the SCS is expected to grow considerably in the coming decades.

  20. Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific

    Directory of Open Access Journals (Sweden)

    T. S. Bibby

    2010-10-01

    Full Text Available Mesoscale eddies in sub-tropical gyres physically perturb the water column and can introduce macronutrients to the euphotic zone, stimulating a biological response by which phytoplankton communities can become dominated by large phytoplankton. Mesoscale eddies are therefore important in driving export in oligotrophic regions of the modern ocean. The character and magnitude of the biological response sustained by eddies are, however, variable. Here we present data from mesoscale eddies in the Sargasso Sea (Atlantic and the waters off Hawai'i (Pacific, alongside mesoscale events that affected the Bermuda Atlantic Time Series (BATS over the past decade. From this analysis, we suggest that the phytoplankton community structure sustained by mesoscale eddies is predetermined by the relative abundance of silicate over nitrate (Si* in the upwelled waters. We present data that demonstrate that mode-water eddies (MWE in the Sargasso Sea upwell locally formed waters with high Si* to the euphotic zone, and that cyclonic eddies in the Sargasso Sea introduce waters with low Si*, a signature that originated in the iron-limited Southern Ocean. We propose that this phenomenon can explain the observed abundance of large-diatom species in MWE and small prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic, cyclonic eddies in waters off Hawai'i induce North Pacific Intermediate Water (NPIW that has high Si* and therefore also appears capable of establishing diatom populations. These observations suggest that the structure of phytoplankton communities sustained by eddies may not be directly related to the physical nature of the eddy but rather to the chemical composition of the upwelled waters. This paper links the biological production and export efficiency of mesoscale eddies to events in spatially and temporally disparate locations.

  1. Phytoplankton Bloom Phenology near Palmer Station Antarctica

    Science.gov (United States)

    Crews, L.; Doney, S. C.; Kavanaugh, M.; Ducklow, H. W.; Schofield, O.; Glover, D. M.

    2015-12-01

    West Antarctic Peninsula (WAP) phytoplankton bloom phenology is coupled to growing season water column stratification precipitated by seasonal warming and the melting of winter sea-ice. Previous studies document declining bloom magnitude over decadal timescales in conjunction with decreasing sea-ice extent and duration in the Northern WAP, but less work has been to done explain the observed inter-annual variability in this region. Here we use a high-resolution in situ time series collected by the Palmer Station Antarctica Long Term Ecological Research program and satellite ocean color imagery to investigate the underlying mechanisms controlling phytoplankton bloom timing and magnitude near Palmer Station. We pair chlorophyll and CTD measurements collected twice per week during the austral summer, 1992—2003, with satellite ocean color and ice fractional cover data to examine bloom development and within-season trends in mixed layer depth. Initial results suggest a possible shift over time with spring/summer blooms occurring earlier in the growing season reflecting earlier sea-ice free conditions. Net phytoplankton accumulation rates are also computed and compared against growth estimates. Our results can be used to develop and validate models of coastal Antarctic primary production that better represent inter-annual primary production variability.

  2. The bacterial abundance and production in the East China Sea:seasonal variations and relationships with the phytoplankton biomass and production

    Institute of Scientific and Technical Information of China (English)

    CHEN Bingzhang; HUANG Bangqin; XIE Yuyuan; GUO Cui; SONG Shuqun; LI Hongbo; LIU Hongbin

    2014-01-01

    The East China Sea is a productive marginal sea with a wide continental shelf and plays an important role in absorbing atmospheric carbon dioxide and transferring terrigenous organic matter to the open ocean. To investigate the roles of heterotrophic bacteria in the biogeochemical dynamics in the East China Sea, bacterial biomasses (BB) and productions (BP) were measured in four cruises. The spatial distributions of the BB and the BP were highly season-dependent. Affected by the Changjiang River discharge, the BB and the BP were high in shelf waters (bottom depth not deeper than 50 m) and generally decreased offshore in August 2009. In December 2009 to January 2010, and November to December 2010, the BB and the BP were high in waters with medium bottom depth. The onshore-offshore decreasing trends of the BB and the BP also existed in May-June 2011, when the BB was significantly higher than in other cruises in shelf break waters (bottom depth deeper than 50 m but not deeper than 200 m). The results of generalized additive models (GAM) suggest that the BB increased with the temperature at a range of 8-20°C, increased with the chlorophyll concentration at a range of 0.02-3.00 mg/m3 and then declining, and decreased with the salinity from 28 to 35. The relationship between the temperature and the log-transformed bacterial specific growth rate (SGR) was linear. The estimated temperature coefficient (Q10) of the SGR was similar with that of the phytoplankton growth. The SGR also increased with the chlorophyll concentration. The ratio of the bacterial to phytoplankton production ranged from less than 0.01 to 0.40, being significantly higher in November-December 2010 than in May-June 2011. Calculated from the bacterial production and growth efficiency, the bacterial respiration consumed, on average, 59%, 72%and 23%of the primary production in August 2009, November-December 2010, and May-June 2011, respectively.

  3. Action spectrum and maximum quantum yield of carbon fixation in natural phytoplankton populations: implications for primary production estimates in the ocean

    Science.gov (United States)

    Arbones, B.; Figueiras, F. G.; Varela, R.

    2000-09-01

    Spectral and non-spectral measurements of the maximum quantum yield of carbon fixation for natural phytoplankton assemblages were compared in order to evaluate their effect on bio-optical models of primary production. Field samples were collected from two different coastal regions of NW Spain in spring, summer and autumn and in a polar environment (Gerlache Strait, Antarctica) during the austral summer. Concurrent determinations were made of spectral phytoplankton absorption coefficient [ aph( λ)], white-light-limited slope of the photosynthesis-irradiance relationships ( αB), carbon uptake action spectra [ αB( λ)], broad-band maximum quantum yields ( φm), and spectral maximum quantum yields [ φm( λ)]. Carbon uptake action spectra roughly followed the shape of the corresponding phytoplankton absorption spectra but with a slight displacement in the blue-green region that could be attributed to imbalance between the two photosystems PS I and PS II. Results also confirmed previous observations of wavelength dependency of maximum quantum yield. The broad-band maximum quantum yield ( φm) calculated considering the measured spectral phytoplankton absorption coefficient and the spectrum of the light source of the incubators was not significantly different form the averaged spectral maximum quantum yield [ overlineφ max(λ) ] ( t-test for paired samples, P=0.34). These results suggest that maximum quantum yield can be estimated with enough accuracy from white-light P- E curves and measured phytoplankton absorption spectra. Primary production at light limiting regimes was compared using four different models with a varying degree of spectral complexity. No significant differences ( t-test for paired samples, P=0.91) were found between a spectral model based on the carbon uptake action spectra [ αB( λ) — model a] and a model which uses the broad-band φm and measured aph( λ) (model b). In addition, primary production derived from constructed action spectra [ ac

  4. Modelling Kara Sea phytoplankton primary production: Development and skill assessment of regional algorithms

    Science.gov (United States)

    Demidov, Andrey B.; Kopelevich, Oleg V.; Mosharov, Sergey A.; Sheberstov, Sergey V.; Vazyulya, Svetlana V.

    2017-07-01

    Empirical region-specific (RSM), depth-integrated (DIM) and depth-resolved (DRM) primary production models are developed based on data from the Kara Sea during the autumn (September-October 1993, 2007, 2011). The model is validated by using field and satellite (MODIS-Aqua) observations. Our findings suggest that RSM algorithms perform better than non-region-specific algorithms (NRSM) in terms of regression analysis, root-mean-square difference (RMSD) and model efficiency. In general, the RSM and NRSM underestimate or overestimate the in situ water column integrated primary production (IPP) by a factor of 2 and 2.8, respectively. Additionally, our results suggest that the model skill of the RSM increases when the chlorophyll specific carbon fixation rate, efficiency of photosynthesis and photosynthetically available radiation (PAR) are used as input variables. The parameterization of chlorophyll (chl a) vertical profiles is performed in Kara Sea waters with different trophic statuses. Model validation with field data suggests that the DIM and DRM algorithms perform equally (RMSD of 0.29 and 0.31, respectively). No changes in the performance of the DIM and DRM algorithms are observed (RMSD of 0.30 and 0.31, respectively) when satellite-derived chl a, PAR and the diffuse attenuation coefficient (Kd) are applied as input variables.

  5. THE IMPACT OF PHYTOPLANKTON ON SPECTRAL WATER TRANSPARENCY IN THE SOUTHERN-OCEAN - IMPLICATIONS FOR PRIMARY PRODUCTIVITY

    NARCIS (Netherlands)

    TILZER, MM; GIESKES, WW; HEUSEL, R; FENTON, N

    1994-01-01

    Spectral water transparency in the Northern Weddell Sea was studied during Austral spring. The depth of the 1-% surface irradiance level (''euphotic depth'') varied between 35 and 109 m and was strongly influenced by phytoplankton biomass. Secchi depths were non-linearly related to euphotic depth. I

  6. Disassembling iron availability to phytoplankton

    Directory of Open Access Journals (Sweden)

    Yeala eShaked

    2012-04-01

    Full Text Available The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron and ecosystem processes. We first examine how phytoplankton acquire free and organically-bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotes and eukaryotes. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as spectrum rather than an absolute all or nothing. We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe compounds and environments, and for gauging the contribution of various Fe substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  7. Disassembling iron availability to phytoplankton.

    Science.gov (United States)

    Shaked, Yeala; Lis, Hagar

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis, and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO(2) drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature, and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron, and ecosystem processes. We first examine how phytoplankton acquire free and organically bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotic and eukaryotic autotrophs. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as a spectrum rather than an absolute "all or nothing." We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe-compounds, and environments, and for gaging the contribution of various Fe-substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  8. Software product quality control

    CERN Document Server

    Wagner, Stefan

    2013-01-01

    Quality is not a fixed or universal property of software; it depends on the context and goals of its stakeholders. Hence, when you want to develop a high-quality software system, the first step must be a clear and precise specification of quality. Yet even if you get it right and complete, you can be sure that it will become invalid over time. So the only solution is continuous quality control: the steady and explicit evaluation of a product's properties with respect to its updated quality goals.This book guides you in setting up and running continuous quality control in your environment. Star

  9. Environmental controls of marine productivity hot spots around Antarctica

    Science.gov (United States)

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

    2015-08-01

    Antarctic coastal polynyas are biologically rich ecosystems that support large populations of mammals and birds and are globally significant sinks of atmospheric carbon dioxide. To support local phytoplankton blooms, these highly productive ecosystems require a large input of iron (Fe), the sources of which are poorly known. Here we assess the relative importance of six different environmental factors in controlling the amount of phytoplankton biomass and rates of net primary production (NPP) in 46 coastal polynyas around Antarctica. Data presented here suggest that melting ice shelves are a primary supplier of Fe to coastal polynyas, with basal melt rates explaining 59% of the between-polynya variance in mean chlorophyll a (Chl a) concentration. In a multiple regression analysis, which explained 78% of the variance in chlorophyll a (Chl a) between polynyas, basal melt rate explained twice as much of the variance as the next most important variable. Fe upwelled from sediments, which is partly controlled by continental shelf width, was also important in some polynyas. Of secondary importance to phytoplankton abundance and NPP were sea surface temperature and polynya size. Surprisingly, differences in light availability and the length of the open water season explained little or none of the variance in either Chl a or NPP between polynyas. If the productivity of coastal polynyas is indeed sensitive to the release of Fe from melting ice shelves, future changes in ice shelf melt rates could dramatically influence Antarctic coastal ecosystems and the ability of continental shelf waters to sequester atmospheric carbon dioxide. This article was corrected on 26 AUG 2015. See the end of the full text for details.

  10. Phytoplankton Productivity in an Arctic Fjord (West Greenland): Estimating Electron Requirements for Carbon Fixation and Oxygen Production.

    Science.gov (United States)

    Hancke, Kasper; Dalsgaard, Tage; Sejr, Mikael Kristian; Markager, Stiig; Glud, Ronnie Nøhr

    2015-01-01

    Accurate quantification of pelagic primary production is essential for quantifying the marine carbon turnover and the energy supply to the food web. Knowing the electron requirement (Κ) for carbon (C) fixation (ΚC) and oxygen (O2) production (ΚO2), variable fluorescence has the potential to quantify primary production in microalgae, and hereby increasing spatial and temporal resolution of measurements compared to traditional methods. Here we quantify ΚC and ΚO2 through measures of Pulse Amplitude Modulated (PAM) fluorometry, C fixation and O2 production in an Arctic fjord (Godthåbsfjorden, W Greenland). Through short- (2h) and long-term (24h) experiments, rates of electron transfer (ETRPSII), C fixation and/or O2 production were quantified and compared. Absolute rates of ETR were derived by accounting for Photosystem II light absorption and spectral light composition. Two-hour incubations revealed a linear relationship between ETRPSII and gross 14C fixation (R2 = 0.81) during light-limited photosynthesis, giving a ΚC of 7.6 ± 0.6 (mean ± S.E.) mol é (mol C)-1. Diel net rates also demonstrated a linear relationship between ETRPSII and C fixation giving a ΚC of 11.2 ± 1.3 mol é (mol C)-1 (R2 = 0.86). For net O2 production the electron requirement was lower than for net C fixation giving 6.5 ± 0.9 mol é (mol O2)-1 (R2 = 0.94). This, however, still is an electron requirement 1.6 times higher than the theoretical minimum for O2 production [i.e. 4 mol é (mol O2)-1]. The discrepancy is explained by respiratory activity and non-photochemical electron requirements and the variability is discussed. In conclusion, the bio-optical method and derived electron requirement support conversion of ETR to units of C or O2, paving the road for improved spatial and temporal resolution of primary production estimates.

  11. Phytoplankton Productivity in an Arctic Fjord (West Greenland: Estimating Electron Requirements for Carbon Fixation and Oxygen Production.

    Directory of Open Access Journals (Sweden)

    Kasper Hancke

    Full Text Available Accurate quantification of pelagic primary production is essential for quantifying the marine carbon turnover and the energy supply to the food web. Knowing the electron requirement (Κ for carbon (C fixation (ΚC and oxygen (O2 production (ΚO2, variable fluorescence has the potential to quantify primary production in microalgae, and hereby increasing spatial and temporal resolution of measurements compared to traditional methods. Here we quantify ΚC and ΚO2 through measures of Pulse Amplitude Modulated (PAM fluorometry, C fixation and O2 production in an Arctic fjord (Godthåbsfjorden, W Greenland. Through short- (2h and long-term (24h experiments, rates of electron transfer (ETRPSII, C fixation and/or O2 production were quantified and compared. Absolute rates of ETR were derived by accounting for Photosystem II light absorption and spectral light composition. Two-hour incubations revealed a linear relationship between ETRPSII and gross 14C fixation (R2 = 0.81 during light-limited photosynthesis, giving a ΚC of 7.6 ± 0.6 (mean ± S.E. mol é (mol C-1. Diel net rates also demonstrated a linear relationship between ETRPSII and C fixation giving a ΚC of 11.2 ± 1.3 mol é (mol C-1 (R2 = 0.86. For net O2 production the electron requirement was lower than for net C fixation giving 6.5 ± 0.9 mol é (mol O2-1 (R2 = 0.94. This, however, still is an electron requirement 1.6 times higher than the theoretical minimum for O2 production [i.e. 4 mol é (mol O2-1]. The discrepancy is explained by respiratory activity and non-photochemical electron requirements and the variability is discussed. In conclusion, the bio-optical method and derived electron requirement support conversion of ETR to units of C or O2, paving the road for improved spatial and temporal resolution of primary production estimates.

  12. Massive phytoplankton blooms under Arctic sea ice.

    Science.gov (United States)

    Arrigo, Kevin R; Perovich, Donald K; Pickart, Robert S; Brown, Zachary W; van Dijken, Gert L; Lowry, Kate E; Mills, Matthew M; Palmer, Molly A; Balch, William M; Bahr, Frank; Bates, Nicholas R; Benitez-Nelson, Claudia; Bowler, Bruce; Brownlee, Emily; Ehn, Jens K; Frey, Karen E; Garley, Rebecca; Laney, Samuel R; Lubelczyk, Laura; Mathis, Jeremy; Matsuoka, Atsushi; Mitchell, B Greg; Moore, G W K; Ortega-Retuerta, Eva; Pal, Sharmila; Polashenski, Chris M; Reynolds, Rick A; Schieber, Brian; Sosik, Heidi M; Stephens, Michael; Swift, James H

    2012-06-15

    Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.

  13. Spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Tiwari, P. K.; Misra, A. K.

    2015-01-01

    The production of toxins by some species of phytoplankton is known to have several economic, ecological, and human health impacts. However, the role of toxins on the spatial distribution of phytoplankton is not well understood. In the present study, the spatial dynamics of a nutrient-phytoplankto...

  14. In situ phytoplankton distributions in the Amundsen Sea Polynya measured by autonomous gliders

    Directory of Open Access Journals (Sweden)

    Oscar Schofield

    2015-10-01

    Full Text Available Abstract The Amundsen Sea Polynya is characterized by large phytoplankton blooms, which makes this region disproportionately important relative to its size for the biogeochemistry of the Southern Ocean. In situ data on phytoplankton are limited, which is problematic given recent reports of sustained change in the Amundsen Sea. During two field expeditions to the Amundsen Sea during austral summer 2010–2011 and 2014, we collected physical and bio-optical data from ships and autonomous underwater gliders. Gliders documented large phytoplankton blooms associated with Antarctic Surface Waters with low salinity surface water and shallow upper mixed layers (< 50 m. High biomass was not always associated with a specific water mass, suggesting the importance of upper mixed depth and light in influencing phytoplankton biomass. Spectral optical backscatter and ship pigment data suggested that the composition of phytoplankton was spatially heterogeneous, with the large blooms dominated by Phaeocystis and non-bloom waters dominated by diatoms. Phytoplankton growth rates estimated from field data (≤ 0.10 day−1 were at the lower end of the range measured during ship-based incubations, reflecting both in situ nutrient and light limitations. In the bloom waters, phytoplankton biomass was high throughout the 50-m thick upper mixed layer. Those biomass levels, along with the presence of colored dissolved organic matter and detritus, resulted in a euphotic zone that was often < 10 m deep. The net result was that the majority of phytoplankton were light-limited, suggesting that mixing rates within the upper mixed layer were critical to determining the overall productivity; however, regional productivity will ultimately be controlled by water column stability and the depth of the upper mixed layer, which may be enhanced with continued ice melt in the Amundsen Sea Polynya.

  15. Spatio-temporal dynamics of phytoplankton and primary production in Lake Tanganyika using a MODIS based bio-optical time series

    DEFF Research Database (Denmark)

    Bergamino, N; Horion, Stéphanie; Stenuite, S

    2010-01-01

    of the chlorophyll-a dataset (July 2002–November 2005), allowed for the separation of the lake in 11 spatially coherent and co-varying regions, with 2 delocalised coastal regions. Temporal patterns of chlorophyll-a showed significant differences between regions. Estimation of the daily primary production in each......Lake Tanganyika, the second largest freshwater ecosystem in Africa, is characterised by a significant heterogeneity in phytoplankton concentration linked to its particular hydrodynamics. To gather a proper understanding of primary production, it is necessary to consider spatial and temporal...... dynamics throughout the lake. In the present work, daily MODIS-AQUA satellite measurements were used to estimate chlorophyll-a concentrations and the diffuse attenuation coefficient (K490) for surface waters. The spatial regionalisation of Lake Tanganyika, based on Empirical Orthogonal Functions...

  16. Seasonal variations of phytoplankton dynamics in Nunatsiavut fjords (Labrador, Canada) and their relationships with environmental conditions

    Science.gov (United States)

    Simo-Matchim, Armelle-Galine; Gosselin, Michel; Blais, Marjolaine; Gratton, Yves; Tremblay, Jean-Éric

    2016-04-01

    We assessed phytoplankton dynamics and its environmental control in four Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during summer, early fall and late fall. Primary production and chlorophyll a (chl a) biomass were measured at seven optical depths, including the depth of subsurface chl a maximum (SCM). Phytoplankton abundance, size structure and taxonomy were determined at the SCM. Principal component analysis and non-metric multidimensional scaling were used to analyze relationships between production, biomass and community composition in relation to environmental variables. We observed a marked seasonal variability, with significant differences in phytoplankton structure and function between summer and fall. Surprisingly, primary production and chl a biomass were not significantly different from one fjord to another. The highest values of primary production (1730 mg C m- 2 day- 1) and chl a biomass (96 mg chl a m- 2) were measured during the summer bloom, and those high values indicate that Labrador fjords are highly productive ecosystems. The summer community showed relatively high abundance of nanophytoplankton (2-20 μm) while the fall community was characterized by low primary production and chl a biomass as well as relatively high abundance of picophytoplankton (< 2 μm). The low value of carbon potentially exported out of the euphotic zone throughout the study (≤ 31% of total primary production) suggests that phytoplankton production was mainly grazed by microzooplankton rather than being exported to greater depths. We observed a mixed assemblage of diatoms and flagellates in summer, whereas the fall community was largely dominated by flagellates. Seasonal variations in phytoplankton dynamics were mainly controlled by the strength of the vertical stratification and by the large differences in day length due to the northerly location of Labrador fjords. This study documents for the very first time phytoplankton structure and function in

  17. Experimental evolution meets marine phytoplankton.

    Science.gov (United States)

    Reusch, Thorsten B H; Boyd, Philip W

    2013-07-01

    Our perspective highlights potentially important links between disparate fields-biological oceanography, climate change research, and experimental evolutionary biology. We focus on one important functional group-photoautotrophic microbes (phytoplankton), which are responsible for ∼50% of global primary productivity. Global climate change currently results in the simultaneous change of several conditions such as warming, acidification, and nutrient supply. It thus has the potential to dramatically change phytoplankton physiology, community composition, and may result in adaptive evolution. Although their large population sizes, standing genetic variation, and rapid turnover time should promote swift evolutionary change, oceanographers have focussed on describing patterns of present day physiological differentiation rather than measure potential adaptation in evolution experiments, the only direct way to address whether and at which rate phytoplankton species will adapt to environmental change. Important open questions are (1) is adaptation limited by existing genetic variation or fundamental constraints? (2) Will complex ecological settings such as gradual versus abrupt environmental change influence adaptation processes? (3) How will increasing environmental variability affect the evolution of phenotypic plasticity patterns? Because marine phytoplankton species display rapid acclimation capacity (phenotypic buffering), a systematic study of reaction norms renders them particularly interesting to the evolutionary biology research community.

  18. The significance of phytoplankton photo-adaptation and benthic pelagic coupling to primary production in the South China Sea: Observations and numerical investigations

    Science.gov (United States)

    Liu, Kon-Kee; Chen, Ying-Jie; Tseng, Chun-Mao; Lin, I.-I.; Liu, Hong-Bin; Snidvongs, Anond

    2007-07-01

    The primary production in the South China Sea (SCS) has been assessed by a coupled physical-biogeochemical model with a simple NPZD ecosystem [Liu et al., 2002. Monsoon-forced chlorophyll distribution and primary production in the SCS: observations and a numerical study. Deep-Sea Research I 49(8), 1387-1412]. In recent years there have been an increasing number of observations in the SCS that may be used to check the validity of the previous approach. The coupled model of the SCS mentioned above employs a photo-adaptation scheme for the phytoplankton growth and uses the simplest bottom boundary condition of an inert benthic layer. These adopted schemes are checked against observations at the South-East Asian Time-series Study (SEATS) Station in the northern SCS and in the Gulf of Thailand. Numerical experiments with or without photo-adaptation or active benthic processes are carried out in this study. Additional experiments are performed with different parameters used for these processes. The observations at the SEATS Station provide direct evidence for the variable chlorophyll-to-nitrogen ratio in phytoplankton as required by photo-adaptation. It is concluded that a photo-adaptation scheme is critical to the phytoplankton growth, especially for the development of the subsurface chlorophyll maximum (SCM). Without photo-adaptation, the average value of the vertically integrated primary production (IPP) over the whole SCS domain would be 35% lower. It is noted that, the modeled SCM occurs at depths shallower than observations due to physical as well as biological processes employed by the model. Increasing the upper limit of the chlorophyll-to-nitrogen ratio, as suggested by observations, enhances chlorophyll level in the lower part of the euphotic zone and raises primary productivity in areas with rich nutrient supply. The observed values of the IPP in the Gulf of Thailand clearly demonstrate the importance of the benthic-pelagic coupling to the nutrient cycle

  19. Spatial and temporal dynamics of size-structured photosynthetic parameters (PAM) and primary production (13C) of pico- and nano-phytoplankton in an atoll lagoon.

    Science.gov (United States)

    Lefebvre, Sébastien; Claquin, Pascal; Orvain, Francis; Véron, Benoît; Charpy, Loïc

    2012-01-01

    Atoll lagoons display a high diversity of trophic states due mainly to their specific geomorphology, and probably to their level and mode of human exploitation. We investigated the functioning of the Ahe atoll lagoon, utilized for pearl oyster farming, through estimations of photosynthetic parameters (pulse amplitude modulation fluorometry) and primary production ((13)C incorporation) measurements of the size structured phytoplankton biomass (2 μm). Spatial and temporal scales of variability were surveyed during four seasons, over 16 months, at four sites within the lagoon. While primary production (P) was dominated by the picophytoplankton, its biomass specific primary productivity (P(B)) was lower than in other atoll lagoons. The variables size fraction of the phytoplankton, water temperature, season, the interaction term station*fraction and site, explained significantly the variance of the data set using redundancy analysis. No significant trends over depth were observed in the range of 0-20 m. A clear spatial pattern was found which was persistent over the seasons: south and north sites were different from the two central stations for most of the measured variables. This pattern could possibly be explained by the existence of water cells showing different water residence time within the lagoon. Photoacclimation strategies of the two size fractions differed through their light saturation coefficient (higher for picophytoplankton), but not through their maximum photosynthetic capacity (ETR(max)). Positive linear relationships between photosynthetic parameters indicated that their dynamic was independent of light availability in this ecosystem, but most probably dependent on nutrient availability and/or rapid changes in the community structure. Spatial and temporal patterns of the measured processes are then further discussed in the context of nutrient availability and the possible role of cultured oysters in nutrient recycling.

  20. Disassembling Iron Availability to Phytoplankton

    OpenAIRE

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis, and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdow...

  1. Disassembling iron availability to phytoplankton

    OpenAIRE

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdown...

  2. Photosynthetic characteristics and estimated growth rates indicate grazing is the proximate control of primary production in the equatorial Pacific

    Science.gov (United States)

    Cullen, John J.; Lewis, Marlon R.; Davis, Curtiss O.; Barber, Richard T.

    1992-01-01

    Macronutrients persist in the surface layer of the equatorial Pacific because the production of phytoplankton is limited; the nature of this limitation has yet to be resolved. Measurements of photosynthesis as a function of irradiance (P-I) provide information on the control of primary productivity, a question of great biogeochemical importance. Accordingly, P-I was measured in the equatorial Pacific along 150 deg W, during February-March 1988. Diel variability of P-I showed a pattern consistent with nocturnal vertical mixing in the upper 20 m followed by diurnal stratification, causing photoinhibition near the surface at midday. Otherwise, the distribution of photosynthetic parameters with depth and the stability of P-I during simulated in situ incubations over 2 days demonstrated that photoadaptation was nearly complete at the time of sampling: photoadaptation had not been effectively countered by upwelling or vertical mixing. Measurements of P-I and chlorophyll during manipulations of trace elements showed that simple precautions to minimize contamination were sufficient to obtain valid rate measurements and that the specific growth rates of phytoplankton were fairly high in situ, a minimum of 0.6/d. Diel variability of beam attenuation also indicated high specific growth rates of phytoplankton and a strong coupling of production with grazing. It appears that grazing is the proximate control on the standing crop of phytoplankton. Nonetheless, the supply of a trace nutrient such as iron might ultimately regulate productivity by influencing species composition and food-web structure.

  3. Photosynthetic characteristics and estimated growth rates indicate grazing is the proximate control of primary production in the equatorial Pacific

    Science.gov (United States)

    Cullen, John J.; Lewis, Marlon R.; Davis, Curtiss O.; Barber, Richard T.

    1992-01-01

    Macronutrients persist in the surface layer of the equatorial Pacific because the production of phytoplankton is limited; the nature of this limitation has yet to be resolved. Measurements of photosynthesis as a function of irradiance (P-I) provide information on the control of primary productivity, a question of great biogeochemical importance. Accordingly, P-I was measured in the equatorial Pacific along 150 deg W, during February-March 1988. Diel variability of P-I showed a pattern consistent with nocturnal vertical mixing in the upper 20 m followed by diurnal stratification, causing photoinhibition near the surface at midday. Otherwise, the distribution of photosynthetic parameters with depth and the stability of P-I during simulated in situ incubations over 2 days demonstrated that photoadaptation was nearly complete at the time of sampling: photoadaptation had not been effectively countered by upwelling or vertical mixing. Measurements of P-I and chlorophyll during manipulations of trace elements showed that simple precautions to minimize contamination were sufficient to obtain valid rate measurements and that the specific growth rates of phytoplankton were fairly high in situ, a minimum of 0.6/d. Diel variability of beam attenuation also indicated high specific growth rates of phytoplankton and a strong coupling of production with grazing. It appears that grazing is the proximate control on the standing crop of phytoplankton. Nonetheless, the supply of a trace nutrient such as iron might ultimately regulate productivity by influencing species composition and food-web structure.

  4. Primary description of surface water phytoplankton pigment patterns in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, R.K.; Anil, A.C.; Narale, D.D.; Chitari, R.R.; Kulkarni, V.V.

    . Biogeochemical controls and feedbacks on ocean primary production. Science 281, 200-206. Gibb, S.W., Barlow, R.G., Cummings, D.G., Rees, N.W., Trees, C.C., Holligan, P., Suggett, D., 2000. Surface phytoplankton pigment distributions in the Atlantic Ocean...

  5. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

    Directory of Open Access Journals (Sweden)

    M. J. Behrenfeld

    2008-11-01

    Full Text Available Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we use satellite-based fluorescence measurements to evaluate light-absorption and energy-dissipation processes influencing phytoplankton light use efficiency and demonstrate its utility as a global physiological indicator of iron-limited growth conditions. This new tool provides a path for monitoring climate-phytoplankton physiology interactions, improving descriptions of light use efficiency in ocean productivity models, evaluating nutrient-stress predictions in ocean ecosystem models, and appraising phytoplankton responses to natural iron enrichments or purposeful iron fertilizations activities.

  6. Iron availability, nitrate uptake, and exportable new production in the subarctic Pacific. [phytoplankton population growth support and atmospheric CO2 removal

    Science.gov (United States)

    Banse, Karl

    1991-01-01

    This paper presents a critique of experimental data and papers by Martin et al. (1989, 1990), who suggested that the phytoplankton growth is iron-limited and that, small additions of iron to large subarctic ocean areas might be a way of removing significant amounts of atmospheric CO2 by increasing phytoplancton growth. Data are presented to show that, in the summer of 1987, the phytoplankton assemblage as a whole was not iron limited, as measured by the bulk removal of nitrate or by the increase of chlorophyll. It is suggested that grazing normally prevents the phytoplankton from reaching concentrations that reduce the iron (and nitrate) to levels that depress division rates drastically.

  7. Phytoplankton Monitoring Network (PMN)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Phytoplankton Monitoring Network (PMN) is a part of the National Centers for Coastal Ocean Science (NCCOS). The PMN was created as an outreach program to connect...

  8. Primary production of phytoplankton in the estuaries of different types (by the example of the Curonian and Vistula Lagoons of the Baltic Sea and the Volga delta)

    Science.gov (United States)

    Aleksandrov, Sergei; Gorbunova, Julia

    2016-04-01

    The aim was to analyze the long-term change of the primary production in large estuaries of different types (Volga delta, Curonian and Vistula Lagoons) under the impact of environmental factors (e.g. climate changes, algal blooms, invasion mollusk). The researches (primary production, chlorophyll, nutrients and others) were carried out monthly from March-April to November in the Vistula and Curonian Lagoons since 1991 to 2015, and in the Lower part of the Volga Delta and fore-delta since 1996 to 2007. The Volga River is the largest river in Europe that flows into the Caspian Sea and it forms a great delta. According to the analysis of long-term data (from the 1960s), the maximum eutrophication and primary production (85-100 gCṡm-2ṡyear-1) in the Volga Delta was observed in the 1980s. In the 1990s, fertilizers use and the input of nutrients into the Volga Delta decreased significantly. Due of the high-flow exchange in the delta, especially during high-water years, observed in the 1980s - early 2000s, this led to a significant decrease in the concentration of nutrients in the water in the Volga Delta. As a result, in the 1990-2000s, the primary production has decreased to the level of 1960s-1970s (40-60 gCṡm-2ṡyear-1) and the process of eutrophication was replaced by de-eutrophication. At present, the trophic status of the Volga delta assessed as mesotrophic. The future trend of phytoplankton primary production of the Volga delta will greatly depend on the scenario of nutrients loading and river runoff. The Curonian Lagoon and Vistula Lagoon are the largest coastal lagoons of the Baltic Sea, relating to the most highly productive water bodies of Europe. The Curonian Lagoon is choke mostly freshwater lagoon, while the Vistula Lagoon is restricted brackish water lagoon. In the last decades the nutrients loading changes, warming trend and biological invasions are observed. The Curonian Lagoon may be characterized as hypertrophic water body. The local climate

  9. Nutrient limitation in Northern Gulf of Mexico (NGOM: phytoplankton communities and photosynthesis respond to nutrient pulse.

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    Full Text Available Although the Mississippi-Atchafalaya River system exports large amounts of nutrients to the Northern Gulf of Mexico annually, nutrient limitation of primary productivity still occurs offshore, acting as one of the major factors controlling local phytoplankton biomass and community structure. Bioassays were conducted for 48 hrs at two stations adjacent to the river plumes in April and August 2012. High Performance of Liquid Chromatography (HPLC combined with ChemTax and a Fluorescence Induction and Relaxation (FIRe system were combined to observe changes in the phytoplankton community structure and photosynthetic activity. Major fluorescence parameters (Fo, Fv/Fm performed well to reveal the stimulating effect of the treatments with nitrogen (N-nitrate and with nitrogen plus phosphate (+NPi. HPLC/ChemTax results showed that phytoplankton community structure shifted with nitrate addition: we observed an increase in the proportion of diatoms and prasinophytes and a decrease in cyanobacteria and prymnesiophytes. These findings are consistent with predictions from trait-based analysis which predict that phytoplankton groups with high maximum growth rates (μmax and high nutrient uptake rates (Vmax readily take advantage of the addition of limiting nutrients. Changes in phytoplankton community structure, if persistent, could trigger changes of particular organic matter fluxes and alter the micro-food web cycles and bottom oxygen consumption.

  10. Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India.

    Science.gov (United States)

    Madhu, N V; Jyothibabu, R; Balachandran, K K

    2010-07-01

    Changes in the autotrophic pico- (0.2-2 microm), nano- (2-20 microm), and microplankton (>20 microm) biomass (chlorophyll a) and primary production were measured in the estuarine and coastal waters off Cochin, southwest coast of India during the onset and establishment of a monsoon. During this period, the estuary was dominated by nutrient-rich freshwater, whereas the coastal waters were characterized with higher salinity values (>30 psu) and less nutrients. The average surface chlorophyll a concentrations and primary production rates were higher in the estuary (average 13.7 mg m(-3) and 432 mgC m(-3) day(-1)) as compared to the coastal waters (5.3 mg m(-3) and 224 mgC m(-3) day(-1)). The nanoplankton community formed the major fraction of chlorophyll a and primary production, both in the estuary (average 85 +/- SD 8.3% and 81.2 +/- SD 3.2%) and the coastal waters (average 73.2 +/- SD 17.2% and 81.9 +/- 15.7%). Nanoplankton had the maximum photosynthetic efficiency in the coastal waters (average 4.8 +/- SD 3.9 mgC mgChl a m(-3) h(-1)), whereas in the estuary, the microplankton had higher photosynthetic efficiency (average 7.4 +/- 7 mgC mgChl a m(-3) h(-1)). The heavy cloud cover and increased water column turbidity not only limit the growth of large-sized phytoplankton in the Cochin estuary and coastal waters but also support the proliferation of nanoplankton community during the monsoon season, even though large variation in nanoplankton chlorophyll a and production exists between these two areas.

  11. Changes in production and respiration during a spring phytoplankton bloom in San Francisco Bay, California, USA: Implications for net ecosystem metabolism

    Science.gov (United States)

    Caffrey, J.M.; Cloern, J.E.; Grenz, C.

    1998-01-01

    We present results of an intensive sampling program designed to measure weekly changes in ecosystem respiration (oxygen consumption in the water column and sediments) around the 1996 spring bloom in South San Francisco Bay, California, USA. Measurements were made at a shallow site (2 m, where mean photic depth was 60% of the water column height) and a deep site (15 m, mean photic depth was only 20% of the water column). We also estimated phytoplankton primary production weekly at both sites to develop estimates of net oxygen flux as the sum of pelagic production (PP), pelagic respiration (PR) and benthic respiration (BR). Over the 14 wk period from February 5 to May 14, PP ranged from 2 to 210, PR from 9 to 289, and BR from 0.1 to 48 mmol O2 m-2 d-1, illustrating large variability of estuarine oxygen fluxes at the weekly time scale. Pelagic production exceeded total respiration at the shallow site, but not at the deep site, demonstrating that the shallow domains are net autotrophic but the deep domains are net heterotrophic, even during the period of the spring bloom. If we take into account the potential primary production by benthic microalgae, the estuary as a whole is net autotrophic during spring, net heterotrophic during the nonbloom seasons, and has a balanced net metabolism over a full annual period. The seasonal shift from net autotrophy to heterotrophy during the transition from spring to summer was accompanied by a large shift from dominance by pelagic respiration to dominance by benthic respiration. This suggests that changes in net ecosystem metabolism can reflect changes in the pathways of energy flow in shallow coastal ecosystems.

  12. Simulation of phytoplankton distribution and variation in the Bering-Chukchi Sea using a 3-D physical-biological model

    Science.gov (United States)

    Hu, Haoguo; Wang, Jia; Liu, Hui; Goes, Joaquim

    2016-06-01

    A three-dimensional physical-biological model has been used to simulate seasonal phytoplankton variations in the Bering and Chukchi Seas with a focus on understanding the physical and biogeochemical mechanisms involved in the formation of the Bering Sea Green Belt (GB) and the Subsurface Chlorophyll Maxima (SCM). Model results suggest that the horizontal distribution of the GB is controlled by a combination of light, temperature, and nutrients. Model results indicated that the SCM, frequently seen below the thermocline, exists because of a rich supply of nutrients and sufficient light. The seasonal onset of phytoplankton blooms is controlled by different factors at different locations in the Bering-Chukchi Sea. In the off-shelf central region of the Bering Sea, phytoplankton blooms are regulated by available light. On the Bering Sea shelf, sea ice through its influence on light and temperature plays a key role in the formation of blooms, whereas in the Chukchi Sea, bloom formation is largely controlled by ambient seawater temperatures. A numerical experiment conducted as part of this study revealed that plankton sinking is important for simulating the vertical distribution of phytoplankton and the seasonal formation of the SCM. An additional numerical experiment revealed that sea ice algae account for 14.3-36.9% of total phytoplankton production during the melting season, and it cannot be ignored when evaluating primary productivity in the Arctic Ocean.

  13. Absorption-based algorithm of primary production for total and size-fractionated phytoplankton in coastal waters

    NARCIS (Netherlands)

    Barnes, M.K.; Tilstone, G.H.; Smyth, T.J.; Suggett, D.J.; Astoreca, R.; Lancelot, C.; Kromkamp, J.C.

    2014-01-01

    Most satellite models of production have been designed and calibrated for use in the open ocean. Coastal waters are optically more complex, and the use of chlorophyll a (chl a) as a first-order predictor of primary production may lead to substantial errors due to significant quantities

  14. Environmental and biological factors controlling the spring phytoplankton bloom at the Patagonian shelf-break front - Degraded fucoxanthin pigments and the importance of microzooplankton grazing

    Science.gov (United States)

    Carreto, José I.; Montoya, Nora G.; Carignan, Mario O.; Akselman, Rut; Acha, E. Marcelo; Derisio, Carla

    2016-08-01

    The aim of this study was to investigate the biotic and abiotic factors controlling the spring phytoplankton blooms at the Patagonian shelf-break front (PSBF). Using a CHEMTAX analysis of HPLC pigment data and other methods, the biomass and spatial variability of plankton communities were studied in four sections (39-48°S) across the PSBF during October 2005. Environmental factors and the biomass and composition of plankton communities exhibited a marked spatial heterogeneity. The latitudinal and cross-shelf progression in the timing of the spring bloom initiation and the nutritive properties of the water masses (Subantarctic Shelf Waters and Malvinas Current Waters) seemed to be the key factors. Three plankton regions were distinguished: (a) Outer shelf (OS), (b) Shelf-break front (SBF) and (c) Malvinas Current (MC). At the highly stratified OS region, the post-bloom community showed low-biomasshigh-phytoplankton diversity formed mainly by small cells (haptophytes 30-62%, diatoms 17-49%, chlorophytes 0-34%, and prasinophytes 0-21% of total Chl a). High amounts of degraded fucoxanthin were found associated with the heterotrophic dinoflagellate, Protoperidinium capurroi. Grazing by this microheterotroph on the diatom population seemed to be the most important factor for the spring bloom decay at the OS. A remarkable quasi monospecific bloom (∼90%) of a nanodiatom (Thalassiosira bioculata var. raripora) associated with high Chl a (up to 20 mg m-3) occurred along (∼1000 km) the SBF and in the most northern extension of the MC. In the southern region, the bloom was developed under absent or incipient density stratification, increasing solar irradiance, high nitrate and phosphate availability, and low numbers of phytoplankton grazers. The average mixedlayer PAR irradiance (<2.0 mol quanta PAR m-2 d-1) and Si:N ratios (<0.2) were low, suggesting a diatom population limited by light and under progressive silicate limitation. The more stratified northern region of the

  15. Assessing spatial and temporal variability of phytoplankton communities' composition in the Iroise Sea ecosystem (Brittany, France): A 3D modeling approach. Part 1: Biophysical control over plankton functional types succession and distribution

    Science.gov (United States)

    Cadier, Mathilde; Gorgues, Thomas; Sourisseau, Marc; Edwards, Christopher A.; Aumont, Olivier; Marié, Louis; Memery, Laurent

    2017-01-01

    Understanding the dynamic interplay between physical, biogeochemical and biological processes represents a key challenge in oceanography, particularly in shelf seas where complex hydrodynamics are likely to drive nutrient distribution and niche partitioning of phytoplankton communities. The Iroise Sea includes a tidal front called the 'Ushant Front' that undergoes a pronounced seasonal cycle, with a marked signal during the summer. These characteristics as well as relatively good observational sampling make it a region of choice to study processes impacting phytoplankton dynamics. This innovative modeling study employs a phytoplankton-diversity model, coupled to a regional circulation model to explore mechanisms that alter biogeography of phytoplankton in this highly dynamic environment. Phytoplankton assemblages are mainly influenced by the depth of the mixed layer on a seasonal time scale. Indeed, solar incident irradiance is a limiting resource for phototrophic growth and small phytoplankton cells are advantaged over larger cells. This phenomenon is particularly relevant when vertical mixing is intense, such as during winter and early spring. Relaxation of wind-induced mixing in April causes an improvement of irradiance experienced by cells across the whole study area. This leads, in late spring, to a competitive advantage of larger functional groups such as diatoms as long as the nutrient supply is sufficient. This dominance of large, fast-growing autotrophic cells is also maintained during summer in the productive tidally-mixed shelf waters. In the oligotrophic surface layer of the western part of the Iroise Sea, small cells coexist in a greater proportion with large, nutrient limited cells. The productive Ushant tidal front's region (1800 mgC·m- 2·d- 1 between August and September) is also characterized by a high degree of coexistence between three functional groups (diatoms, micro/nano-flagellates and small eukaryotes/cyanobacteria). Consistent with

  16. Does biodiversity of estuarine phytoplankton depend on hydrology?

    NARCIS (Netherlands)

    Ferreira, JG; Wolff, WJ; Simas, TC; Bricker, SB

    2005-01-01

    Phytoplankton growth in estuaries is controlled by factors such as flushing, salinity tolerance, light, nutrients and grazing. Here, we show that biodiversity of estuarine phytoplankton is related to flushing, and illustrate this for some European estuaries. The implications for the definition of re

  17. Effect of phytoplankton-released organic matter on the production and properties of the primary marine aerosol (Invited)

    Science.gov (United States)

    Fuentes, E.; Coe, H.; Green, D.; de Leeuw, G.; McFiggans, G.

    2010-12-01

    This study investigates the effect of the biogenic matter exuded by marine biota on the production and properties of the submicron primary sea-spray, based on the laboratory simulation of marine aerosol formation from seawater enriched with organic matter released by laboratory-grown algal cultures. Primary aerosol formation by bubble bursting was reproduced by using a plunging water jet generation system. Particle production experiments with seawater enriched in marine exudate marine organics. An increase in the production of particles production experiments. Estimations of the relationship between Chl-a biomass and seawater OC concentration indicated that effects on particle fluxes due to biological activity are likely to occur in diatom blooms with Chl-a diatom biomass >0.35-2 mg/m3 (OC>175 µM), depending on the primary organic production conditions in the algal bloom. Analysis of the hygroscopicity and cloud condensation nuclei (CCN) activity of the organics-enriched primary aerosol indicated both a suppression of the water uptake and the CCN activity with increasing amount of organic exudate in the source seawater. The increase in the CCN number likely to occur in algal bloom areas due to the potential increase in particle production would therefore be counteracted by the reduction of the particle CCN activity induced by the incorporation of organic matter. Calculations of the primary particle composition using a mixing rule yielded organic mass fractions in the range 5-37%, with the organic particle enrichment proportional to the seawater organic content. This level of organic mass fraction is in contrast with values up to 80% reported from atmospheric measurements, suggesting the presence of organics of secondary origin in the atmospheric marine aerosol.

  18. Seasonal Phytoplankton Dynamics in the Eastern Tropical Atlantic

    Science.gov (United States)

    Monger, Bruce; McClain, Charles; Murtugudde, Ragu

    1997-01-01

    The coastal zone color scanner (CZCS) that operated aboard the Nimbus 7 satellite provided extensive coverage of phytoplankton pigment concentrations in the surface waters of the eastern tropical Atlantic (ETA) from March 1979 to February 1980 and coincided with four major research cruises to this region. Total primary production within the ETA (5 deg N-10 deg S, 25 deg W-10 deg E) was determined from CZCS pigment estimates and an empirical algorithm derived from concurrent in situ data taken along 4 deg W that relates near-surface chlorophyll concentration and integrated primary production. We estimated an average annual production for the ETA of 2.3 Gt C/yr with an associated 3.5-fold seasonal variation in the magnitude of this production. We describe the principal physical mechanisms controlling seasonal phytoplankton dynamics within the ETA and propose that in addition to seasonal change in the thermocline depth, one must also consider changes in the depth of the equatorial under current. An extensive validation effort indicates that the standard CZCS global products are a conservative estimate of pigment concentrations in ETA surface waters. Significant underestimates by the CZCS global products were observed in June and July which we attributed, in part, to aerosol correction errors and, more importantly, to errors caused by a significant reduction in the concentration of near-surface dissolved organic matter that resulted from strong equatorial upwelling.

  19. Linking small-scale circulation dynamics with large-scale seasonal production (phytoplankton) in the Southern Ocean

    CSIR Research Space (South Africa)

    Nicholson, S

    2012-10-01

    Full Text Available Understanding the seasonal and intra-seasonal (daily to weekly) changes of the upper ocean and the impact on the primary production in the Southern Ocean is key to better understanding the sensitivities of the global carbon cycle....

  20. Earth's Most Important Producers: Meet the Phytoplankton!

    Science.gov (United States)

    Marrero, Meghan E.; Stevens, Nicole

    2011-01-01

    The ocean is home to some of Earth's most important producers. Single-celled organisms in the ocean are responsible for more than half of Earth's productivity, as well as most of its oxygen. Phytoplankton are single-celled, plantlike organisms. That is, they have chloroplasts and perform photosynthesis, but are not true plants, which are typically…

  1. Coupled Response of Bacterial Production to a Wind-induced Fall Phytoplankton Bloom and Sediment Resuspension in the Chukchi Sea Shelf, Western Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mario Uchimiya

    2016-11-01

    Full Text Available Heterotrophic bacterial abundance and production, dissolved free amino acid (DFAA and dissolved combined amino acid (DCAA concentrations, and other microbial parameters were determined for seawater samples collected at a fixed station (maximum water depth, 56 m deployed on the Chukchi Sea Shelf, in the western Arctic Ocean, during a 16-day period in September 2013. During the investigation period, the sampling station experienced strong winds and a subsequent phytoplankton bloom, which was thought to be triggered by enhanced vertical mixing and upward nutrient fluxes. In this study, we investigated whether bacterial and dissolved amino acid parameters changed in response to these physical and biogeochemical events. Bacterial abundance and production in the upper layer increased with increasing chlorophyll a concentration, despite a concomitant decrease in seawater temperature from 3.2°C to 1.5°C. The percentage of bacteria with high nucleic acid content during the bloom was significantly higher than that during the prebloom period. The ratio of the depth-integrated (0–20 m bacterial production to primary production differed little between the prebloom and bloom period, with an overall average value of 0.14 ± 0.03 (± standard deviation, n = 8. DFAA and DCAA concentrations varied over a limited range throughout the investigation, indicating that the supply and consumption of labile dissolved amino acids were balanced. These results indicate that there was a tightly coupled, large flow of organic carbon from primary producers to heterotrophic bacteria during the fall bloom. Our data also revealed that bacterial production and abundance were high in the bottom nepheloid (low transmittance layer during strong wind events, which was associated with sediment resuspension due to turbulence near the seafloor. The impacts of fall wind events, which are predicted to become more prominent with the extension of the ice-free period, on bacterial

  2. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    KAUST Repository

    Pinedo-González, Paulina

    2015-10-25

    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.

  3. A review of phytoplankton dynamics in tropical African lakes

    Directory of Open Access Journals (Sweden)

    Charles F. Musil

    2010-03-01

    Full Text Available This paper provides a synthesis of current knowledge on phytoplankton production, seasonality, and stratification in tropical African lakes and considers the effects of nutrient enrichment and the potential impacts of climate warming on phytoplankton production and composition. Tropical African lakes are especially sensitive to climate warming as they experience wide fluctuations in the thermocline over a narrow range of high water temperatures. Recent climate warming has reduced phytoplankton biomass and production in the lakes. A decline in the production of palatable chlorophytes and an increase in cyanobacteria has led to reduced zooplankton production and a consequent decline in fish stocks, all of which can be associated with the elevated water temperatures. This indicates that even moderate climate warming may destabilise phytoplankton dynamics in tropical African lakes, thereby reducing water quality and food resources for planktivorous fish, with consequent negative impacts on human livelihoods.

  4. A seasonal diary of phytoplankton in the North Atlantic

    DEFF Research Database (Denmark)

    Lindemann, Christian; St. John, Michael

    2014-01-01

    In recent years new biological and physical controls have been suggested to drive phytoplankton bloom dynamics in the North Atlantic. A better understanding of the mechanisms driving primary production has potentially important implications for the understanding of the biological carbon pump......, as it has for prediction of the system in climate change scenarios. However, the scientific discussion regarding this topic has generally failed to integrate the different drivers into a coherent picture, often rendering the proposed mechanisms exclusive to each other. We feel that the suggested mechanisms...

  5. Model estimating the effect of marginal ice zone processes on the phytoplankton primary production and air-sea flux of CO2 in the Barents Sea

    Science.gov (United States)

    Dvornikov, Anton; Sein, Dmitry; Ryabchenko, Vladimir; Gorchakov, Victor; Martjyanov, Stanislav

    2016-04-01

    This study is aimed to assess the impact of sea ice on the primary production of phytoplankton (PPP) and air-sea CO2 flux in the Barents Sea. To get the estimations, we apply a three-dimensional eco-hydrodynamic model based on the Princeton Ocean Model which includes: 1) a module of sea ice with 7 categories, and 2) the 11-component module of marine pelagic ecosystem developed in the St. Petersburg Branch, Institute of Oceanology. The model is driven by atmospheric forcing, prescribed from the reanalysis NCEP / NCAR, and conditions on the open sea boundary, prescribed from the regional model of the atmosphere-ocean-sea ice-ocean biogeochemistry, developed at Max Planck Institute for Meteorology, Hamburg. Comparison of the model results for the period 1998-2007 with satellite data showed that the model reproduces the main features of the evolution of the sea surface temperature, seasonal changes in the ice extent, surface chlorophyll "a" concentration and PPP in the Barents Sea. Model estimates of the annual PPP for whole sea, APPmod, appeared in 1.5-2.3 times more than similar estimates, APPdata, from satellite data. The main reasons for this discrepancy are: 1) APPdata refers to the open water, while APPmod, to the whole sea area (under the pack ice and marginal ice zone (MIZ) was produced 16 - 38% of PPP); and 2) values of APPdata are underestimated because of the subsurface chlorophyll maximum. During the period 1998-2007, the modelled maximal (in the seasonal cycle) sea ice area has decreased by 15%. This reduction was accompanied by an increase in annual PPP of the sea at 54 and 63%, based, respectively, on satellite data and the model for the open water. According to model calculations for the whole sea area, the increase is only 19%. Using a simple 7-component model of oceanic carbon cycle incorporated into the above hydrodynamic model, the CO2 exchange between the atmosphere and sea has been estimated in different conditions. In the absence of biological

  6. Limnology in El Dorado: some surprising aspects of the regulation of phytoplankton productive capacity in a high-altitude Andean lake (Laguna de Guatavita, Colombia).

    Science.gov (United States)

    Donato, Jhon; Jimenez, Paola; Reynolds, Colin

    2012-09-01

    High-altitude mountain lakes remain understudied, mostly because of their relative inaccessibility. Laguna de Guatavita, a small, equatorial, high-altitude crater lake in the Eastern Range of the Colombian Andes, was once of high cultural importance to pre-Columban inhabitants, the original location of the legendary El Dorado. We investigated the factors regulating the primary production in Laguna de Guatavita (4degrees58'50" N - 73degrees46'43" W, alt. 2 935m.a.s.l., area: 0.11km2, maximum depth: 30m), during a series of three intensive field campaigns, which were conducted over a year-long period in 2003-2004. In each, standard profiles of temperature, oxygen concentration and light intensity were determined on each of 16-18 consecutive days. Samples were collected and analysed for chlorophyll and for biologically-significant solutes in GF/F-filtered water (NH4+, NO3(-), NO2(-); soluble reactive phosphorus). Primary production was also determined, by oxygen generation, on each day of the campaign. Our results showed that the productive potential of the lake was typically modest (campaign averages of 45-90mg C/m2.h) but that many of the regulating factors were not those anticipated intuitively. The lake is demonstrably meromictic, reminiscent ofkarstic dolines in higher latitudes, its stratification being maintained by solute- concentration gradients. Light penetration is poor, attributable to the turbidity owing to fine calcite and other particulates in suspension. Net primary production in the mixolimnion of Laguna de Guavita is sensitive to day-to-day variations in solar irradiance at the surface. However, deficiencies in nutrient availability, especially nitrogen, also constrain the capacity of the lake to support a phytoplankton. We deduced that Laguna de Guatavita is something of a limnological enigma, atypical of the common anticipation of a "mountain lake". While doubtlessly not unique, comparable descriptions of similar sites elsewhere are sufficiently

  7. Genetic diversity of marine Synechococcus and co-occurring cyanophage communities: evidence for viral control of phytoplankton.

    Science.gov (United States)

    Mühling, Martin; Fuller, Nicholas J; Millard, Andrew; Somerfield, Paul J; Marie, Dominique; Wilson, William H; Scanlan, David J; Post, Anton F; Joint, Ian; Mann, Nicholas H

    2005-04-01

    Unicellular cyanobacteria of the genus Synechococcus are a major component of the picophytoplankton and make a substantial contribution to primary productivity in the oceans. Here we provide evidence that supports the hypothesis that virus infection can play an important role in determining the success of different Synechococcus genotypes and hence of seasonal succession. In a study of the oligotrophic Gulf of Aqaba, Red Sea, we show a succession of Synechococcus genotypes over an annual cycle. There were large changes in the genetic diversity of Synechococcus, as determined by restriction fragment length polymorphism analysis of a 403- bp rpoC1 gene fragment, which was reduced to one dominant genotype in July. The abundance of co-occurring cyanophage capable of infecting marine Synechococcus was determined by plaque assays and their genetic diversity was determined by denaturing gradient gel electrophoresis analysis of a 118-bp g20 gene fragment. The results indicate that both abundance and genetic diversity of cyanophage covaried with that of Synechococcus. Multivariate statistical analyses show a significant relationship between cyanophage assemblage structure and that of Synechococcus. These observations are consistent with cyanophage infection being a major controlling factor in picophytoplankton succession.

  8. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

    Directory of Open Access Journals (Sweden)

    M. J. Behrenfeld

    2009-05-01

    Full Text Available Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.

  9. Studies on Antarctic phytoplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Pant, A.

    Ice-edge data from a single polynya station at 70 degrees S 11 degrees E over a 2-month period is assessed in relation to previously published work in similar environments. The phytoplankton community seems to be composed of 2 quite different...

  10. Seasonal Variability in Phytoplankton Responses to Water Accommodated Petroleum Hydrocarbons in the Northern Gulf of Mexico

    Science.gov (United States)

    Cole, L. K.; Krause, J. W.; Thamatrakoln, K.

    2016-02-01

    Seasonality in the relative abundance of phytoplankton groups is primarily due to environmental variables such as light availability, nutrient availability and flux as well as shifts in higher trophic level abundance. This variation is amplified in shallow coastal waters, where the biology and physical characteristics are influenced by dynamic temporal variation in freshwater plume influx. The flooding of the Gulf of Mexico with organic matter from the Deepwater Horizon Oil spill in April 2010 highlighted the lack of regional baseline knowledge regarding phytoplankton succession and the effect of petrocarbon loading on different phytoplankton groups. To understand the effect of perturbations on seasonal succession, we are conducting monthly multi-day grow out experiments using water from the Alabama Coast, in the northern Gulf of Mexico. These assessments are conducted using treatments of water accommodated fraction of crude oil (WAF, MC252 Surrogate Crude Oil) and chemically enhanced WAF (CEWAF, Crude + Dasic International Slickgone NS®) relative to controls. We are examining changes in photophysiology, productivity, biomass accumulation and community composition. Preliminary results show significant photochemical quenching of chlorophyll fluorescence after one day of exposure to 10% WAF. In addition, significant divergences in chlorophyll concentration were observed among oil exposure treatments. These results imply strong sublethal effects for the aggregate phytoplankton community. Ongoing time-series results will be presented to examine whether similar sublethal effects are observed throughout the year and whether the magnitude of this variation is affected by the encountered community composition and hydrographic conditions. Given that phytoplankton mediate the transfer of carbon to higher trophic levels, understanding the effect of perturbations on seasonal relative phytoplankton abundance has implications for ecosystem resilience as a whole.

  11. Effects of varied nitrate and phosphate supply on polysaccharidic and proteinaceous gel particles production during tropical phytoplankton bloom experiments

    Directory of Open Access Journals (Sweden)

    A. Engel

    2015-04-01

    Full Text Available It has been suggested that oxygen minimum zones (OMZ will expand in the tropical oceans as a result of global change with potential consequences for marine element cycling, such as an increase in anaerobic nitrogen loss, resulting in a lower supply of nitrate relative to phosphate to the euphotic zone. So far, the effects of changes in nutrient ratios on organic matter recycling and export fluxes are not well understood. Here, were investigated how different phosphate (Varied P: 0.15–1.58 μmol L−1 or nitrate (Varied N: 1.9–21.9 μmol L−1 concentrations affect the abundance and size distribution of polysaccharidic transparent exopolymer particles (TEP, which are suggested to enhance particle aggregation and export fluxes, and on proteinaceous coomassie stainable particles (CSP, a supposedly good substrate for heterotrophic bacteria. Two series of mesocosm bloom experiments were conducted with natural plankton communities collected from the Eastern Tropical North Atlantic (ETNA close to Cape Verde in October 2012. Until bloom peak, a positive correlation between gel particle abundance and Chl a concentration was determined, linking the release of dissolved gel precursors and the subsequent formation of gel particles to autotrophic production. After bloom peak, gel particle abundance remained stable or even increased, implying a continued partitioning of dissolved into particulate organic matter after biomass production itself ceased. During both experiments, differences between TEP and CSP dynamics were observed; TEP were generally more abundant than CSP. Changes in size distribution indicated aggregation of TEP during the bloom, while newly formed CSP decomposed. Abundance of gel particles clearly increased with nitrate concentration during the second experiment, suggesting that changes in [DIN]:[DIP] ratios can affect gel particle formation with potential consequences for carbon and nitrogen cycling as well as food web dynamics in

  12. High production of nitrous oxide (N2O, methane (CH4 and dimethylsulphoniopropionate (DMSP in a massive marine phytoplankton culture

    Directory of Open Access Journals (Sweden)

    L. Farías

    2010-09-01

    Full Text Available The production of large amounts of algal biomass for different purposes such as aquaculture or biofuels, may cause impacts on the marine environment. One such impact is the production of radiatively active trace gases and aerosols with climate cooling (dimethyl sulfide DMS and its precursor DMSP and warming (N2O and CH4 effects. Total and dissolved DMSP, N2O and CH4, together with other environmental variables were monitored daily for 46 days within a massive microalgae monoculture of Nannochloris (Chlorophyceae in an open pond system. The growth of this green microalgae was stimulated by the addition of N- and P-rich salts, resulting in exponential growth (growth phase during the first 17 days observed by cell abundance (1 × 106 to 4.4 × 106 cell mL−1 and Chl-a levels (from 1.4 to 96 mg Chl-a m−3 followed by a decrease in both Chl-a and cell abundance (senescence phase. Total DMSP (from 6.3 to 142 μmol m−3, dissolved DMSP i.e. 5.8 to 137 μmol m−3 and N2O (from 8 to 600 μmol m−3 abruptly peaked during the senescence phase, whereas CH4 steadily increased between 2 and 10 μmol m−3 during the growth phase. Different ratios between tracers and Chl-a during both phases reveal different biochemical processes involved in the cycling of these gases and tracers. Our results show that despite the consumption of large quantities of CO2 by the massive algal culture, a minor amount of DMS and huge amounts of greenhouse gases were produced, in particular N2O, which has a greater radiative effect per molecule than CO2. These findings have important implications for biogeochemical studies and for environmental management of aquaculture activities.

  13. Phytoplankton size impact on export flux in the global ocean

    Science.gov (United States)

    Mouw, Colleen B.; Barnett, Audrey; McKinley, Galen A.; Gloege, Lucas; Pilcher, Darren

    2016-10-01

    Efficiency of the biological pump of carbon to the deep ocean depends largely on biologically mediated export of carbon from the surface ocean and its remineralization with depth. Global satellite studies have primarily focused on chlorophyll concentration and net primary production (NPP) to understand the role of phytoplankton in these processes. Recent satellite retrievals of phytoplankton composition now allow for the size of phytoplankton cells to be considered. Here we improve understanding of phytoplankton size structure impacts on particle export, remineralization, and transfer. A global compilation of particulate organic carbon (POC) flux estimated from sediment traps and 234Th are utilized. Annual climatologies of NPP, percent microplankton, and POC flux at four time series locations and within biogeochemical provinces are constructed. Parameters that characterize POC flux versus depth (export flux ratio, labile fraction, and remineralization length scale) are fit for time series locations, biogeochemical provinces, and times of the year dominated by small and large phytoplankton cells where phytoplankton cell size show enough dynamic range over the annual cycle. Considering all data together, our findings support the idea of high export flux but low transfer efficiency in productive regions and vice versa for oligotrophic regions. However, when parsing by dominant size class, we find periods dominated by small cells to have both greater export flux efficiency and lower transfer efficiency than periods when large cells comprise a greater proportion of the phytoplankton community.

  14. Phytoplankton Identification Manual

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Desai, S.R.

    of Environment & Forests, New Delhi 3 FOREWORD Since its inception in 1966 the National Institute of Oceanography is involved in taxonomic classification of marine phytoplankton, zooplankton, benthos and other flora and fauna under the Project ? Measurement... details of taxonomic classification and description of the concerned organisms / species. All the figures are well illustrated and detailed identification key is provided. This should surely guide even a beginner to understand the identification...

  15. PHYTOPLANKTON OF CASPIAN

    Directory of Open Access Journals (Sweden)

    Aysha Sharapatinovna Gasanova

    2015-01-01

    Full Text Available Aim. The composition of the species of the phytoplankton in the Russian sector of the Caspian Sea in conditions of transgression, anthropogenic and chemical contamination has been studied.Location.The Russian sector of the Caspian SeaMethods. The phytoplankton samples were collected at the depths of 8 – 50m by the use of the Nansen bathometer and subsequently were fixed in 4% formalin. The office processing was carried out in a box of Nozhotta type, which has the volume of 0.1 ml and the triplicate surface, under the light microscope of Biolam P15. The system of domestic diamotologists was used during the classification of Bacillariaphyta, as for the classification of Dinophyta, the Dodge scheme was applied. Cyanophyta algae were classified according to the system of A.A. Elenkina with the amendments adopted by A.I. Proshkin-Lavrenko and V.V. Makarova. The classification of the Chlorophyta division has been done according to the Smith system.Results, main conclusions. Presented the taxonomic structure and the lists of species of the phytoplankton community in the sea coastal shallow waters Russian sector of the Caspian Sea have been presented. A high floristic diversity and domination of small cell forms are characteristics of the modern structure of the coastal shoal waters of the Dagestan part of the Caspian Sea. The auttaclimatizant of 1934, Pseudosolenia calcaravis, has not been discovered in the plankton of the researched water area. The phytoplankton community has been represented by 58 species of six groups: Cyanophyta, Bacillariaphyta, Dinophyta, Euglenophyta, Chlorophyta and the small flagellate. Bacillariaphyta were the basis of both the taxonomic diversity and the biomass. Cyanophita prevailed in number.

  16. Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal.

    Science.gov (United States)

    Brogueira, Maria José; Oliveira, Maria do Rosário; Cabeçadas, Graça

    2007-12-01

    In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.

  17. Monitoring and toxicity evaluation of phytoplankton on lithium manganese oxide adsorbents at lithium recovery pilot plant field.

    Science.gov (United States)

    Yoon, H. O.; Kim, J. A.; Kim, J. C.; Chung, K. S.; Ryu, J. H.

    2015-12-01

    For recovery of rare mineral resources such as lithium or boron from seawater, the lithium adsorbent material have been made by Korea Institute of Geoscience and Mineral Resources (KIGAM) and pilot plant was conducted in Okgye Harbor, Gangneung, Korea. The application of lithium adsorbent in pilot plant, it is important to consider the impact on the marine environment. Especially phytoplankton communities are important marine microorganism to represent marine primary product. At the same time, phytoplankton is possible to induce the decrease of lithium recovery rate due to cause of biofouling to surfaces of lithium adsorbents. Therefore long-term and periodic monitoring of phytoplankton is necessary to understand the environmental impact and biofouling problems near the lithium pilot plant. The abundance and biomass of phytoplankton have been evaluated through monthly interval sampling from February 2013 to May 2015. Abundance and species diversity of phytoplankton went up to summer from winter. When lithium adsorbents were immersing to seawater, eco-toxicities of released substances were determined using Microtox with bioluminescence bacteria Vibrio fischeri. The adsorbents were soaked in sterilized seawater and aeration for 1, 3, 5, 7, 10 and 14 days intervals under controlled temperature. Maximum EC50 concentration was 61.4% and this toxicity was showed in more than 10 days exposure.

  18. Ecotoxicology of bromoacetic acid on estuarine phytoplankton.

    Science.gov (United States)

    Gordon, Ana R; Richardson, Tammi L; Pinckney, James L

    2015-11-01

    Bromoacetic acid is formed when effluent containing chlorine residuals react with humics in natural waters containing bromide. The objective of this research was to quantify the effects of bromoacetic acid on estuarine phytoplankton as a proxy for ecosystem productivity. Bioassays were used to measure the EC50 for growth in cultured species and natural marine communities. Growth inhibition was estimated by changes in chlorophyll a concentrations measured by fluorometry and HPLC. The EC50s for cultured Thalassiosira pseudonana were 194 mg L(-1), 240 mg L(-1) for Dunaliella tertiolecta and 209 mg L(-1) for Rhodomonas salina. Natural phytoplankton communities were more sensitive to contamination with an EC50 of 80 mg L(-1). Discriminant analysis suggested that bromoacetic acid additions cause an alteration of phytoplankton community structure with implications for higher trophic levels. A two-fold EC50 decrease in mixed natural phytoplankton populations affirms the importance of field confirmation for establishing water quality criteria.

  19. Phytoplankton of the North Sea and its dynamics: A review

    Science.gov (United States)

    Reid, P. C.; Lancelot, C.; Gieskes, W. W. C.; Hagmeier, E.; Weichart, G.

    microscopic observations has been documented by measurements of taxon-specific pigments such as chlorophyll b (green algae), alloxanthin (Cryptophyceae) and 19' - hexanolyloxyfucoxanthin (Prymnesiophyceae or Haptophyceae). Analysis of time series of satellite images is a promising way to assess in a quantitative and, more important, synoptic way the patchy distribution of phytoplankton over large regions. Growth processes of the phytoplankton respond according to variables amenable to such satellite remote sensing. Empirical and theoretical relationships that can be established between chlorophyll a, 14C uptake, turbidity, stratification, suspended sediment type, irradiance and temperature in some well-investigated areas make remote sensing a potential tool to obtain reliable estimates of primary production in the whole North Sea. The 14C method for estimates of the rate of algal growth processes appears to agree reasonably well with other methods, both involving incubation of samples and in situ measurements of temporal changes of oxygen and pH. The level of net primary production is 250 g C.m -2.a -1 in the central North Sea, 150 to 200 g C.m -2.a -1 in the northern North Sea, and 200 g in the South. The main metabolic processes involved in phytoplankton growth have been modelled mathematically in terms of the most important controlling environmental parameters. Such parameters comprise not only those of a chemical signature (micro- and macronutrients, both inorganic and organic) but also physical effects of vertical mixing and sinking, and biological effects including allelopathic interactions, antibiotic excretions, vertical migration, and mortality due to grazing and parasitism. The balance between primary production and consumption of organic matter appears to vary both geographically and seasonally. The process of regeneration of primary products both in the water column and in and near the bottom seems to be of major importance. Future research should center around a

  20. Pigment signatures of phytoplankton communities in the Beaufort Sea

    Science.gov (United States)

    Coupel, P.; Matsuoka, A.; Ruiz-Pino, D.; Gosselin, M.; Marie, D.; Tremblay, J.-É.; Babin, M.

    2015-02-01

    Phytoplankton are expected to respond to recent environmental changes of the Arctic Ocean. In terms of bottom-up control, modifying the phytoplankton distribution will ultimately affect the entire food web and carbon export. However, detecting and quantifying changes in phytoplankton communities in the Arctic Ocean remains difficult because of the lack of data and the inconsistent identification methods used. Based on pigment and microscopy data sampled in the Beaufort Sea during summer 2009, we optimized the chemotaxonomic tool CHEMTAX (CHEMical TAXonomy) for the assessment of phytoplankton community composition in an Arctic setting. The geographical distribution of the main phytoplankton groups was determined with clustering methods. Four phytoplankton assemblages were determined and related to bathymetry, nutrients and light availability. Surface waters across the whole survey region were dominated by prasinophytes and chlorophytes, whereas the subsurface chlorophyll maximum was dominated by the centric diatoms Chaetoceros socialis on the shelf and by two populations of nanoflagellates in the deep basin. Microscopic counts showed a high contribution of the heterotrophic dinoflagellates Gymnodinium and Gyrodinium spp. to total carbon biomass, suggesting high grazing activity at this time of the year. However, CHEMTAX was unable to detect these dinoflagellates because they lack peridinin. In heterotrophic dinoflagellates, the inclusion of the pigments of their prey potentially leads to incorrect group assignments and some misinterpretation of CHEMTAX. Thanks to the high reproducibility of pigment analysis, our results can serve as a baseline to assess change and spatial or temporal variability in several phytoplankton populations that are not affected by these misinterpretations.

  1. Production control system specified quality sausage products

    Directory of Open Access Journals (Sweden)

    A. V. Tokarev

    2016-01-01

    Full Text Available The problem of management of production target in technological system of production of sausages of the set quality is considered in article. Decomposition of technological system is considered. Functions of management are allocated: formation of an optimum compounding of forcemeat, expert analysis of a compounding, laboratory analysis of a compounding and its statement. Information technology of interaction of these functions is offered. The mathematical problem definition of finding of an optimum compounding meat product with use of possible substitutes of ingredients is presented. This mathematical problem is a classical linear programming problem whose solution has the standard program. Since the manufacture of the finished product are various nonlinear effects are taken into account at the present time it is practically impossible, the methodology provided in this operation "Expert analysis of the formulation" and "Laboratory analysis of the finished product." An example of calculating the optimum alternative base recipe "Sausages “Viennese with cheese”" TS 9213-010-40155161-2002. For an alternative formulation demands were made at a cost of meat, the ingredient composition, as well as the final product organoleptic and physic-chemical indicators should comply with regulatory requirements "Sausages “Viennese with cheese”" TS 9213-010-40155161-2002. Indicator acid activity (pH calculated stuffing formulation should be in the range 6.0-6.3. As a partial replacement for the main raw material have been proposed acceptable substitutes. It was necessary to calculate on the basis of the formulation "Sausages “Viennese with cheese”" TS 9213-010-40155161-2002 optimal price and quality alternative formulation. As a result of depreciation of the value of alternative stuffing recipe was 14,5 % when all of the restrictions on the consumer properties. The proposed information technology implemented in the software package "Multi

  2. Observing and modelling phytoplankton community structure in the North Sea

    Science.gov (United States)

    Ford, David A.; van der Molen, Johan; Hyder, Kieran; Bacon, John; Barciela, Rosa; Creach, Veronique; McEwan, Robert; Ruardij, Piet; Forster, Rodney

    2017-03-01

    Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models are therefore not yet frequently validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical-biogeochemical ocean models, the biogeochemical components of which are different variants of the widely used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. An initial comparison of the formulations and parameterizations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed phytoplankton community structure. These findings will help inform future model development, which should be coupled

  3. Volatile products controlling Titan's tholins production

    KAUST Repository

    Carrasco, Nathalie

    2012-05-01

    A quantitative agreement between nitrile relative abundances and Titan\\'s atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan\\'s atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O\\'Brien et al. (Sciamma-O\\'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O\\'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan\\'s INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.

  4. The Effect of Atrazine on Louisiana Gulf Coast Estuarine Phytoplankton.

    Science.gov (United States)

    Starr, Alexis V; Bargu, Sibel; Maiti, Kanchan; DeLaune, Ronald D

    2017-02-01

    Pesticides may enter water bodies in areas with a high proportion of agricultural land use through surface runoff, groundwater discharge, and erosion and thus negatively impact nontarget aquatic organisms. The herbicide atrazine is used extensively throughout the Midwest and enters the Mississippi River through surface runoff and groundwater discharge. The purpose of this study was to determine the extent of atrazine contamination in Louisiana's estuaries from Mississippi River water under different flow and nutrient regimes (spring and summer) and its effect on the biomass and oxygen production of the local phytoplankton community. The results showed that atrazine was consistently present in these systems at low levels. Microcosm experiments exposed to an atrazine-dilution series under low and high nutrient conditions to determine the phytoplankton stress response showed that high atrazine levels greatly decreased phytoplankton biomass and oxygen production. Phytoplankton exposed to low and moderate atrazine levels under high nutrient conditions were able to recover after an extended acclimation period. Communities grown under high nutrient conditions grew more rapidly and produced greater levels of oxygen than the low nutrient treatment groups, thus indicating that atrazine exposure may induce a greater stress response in phytoplankton communities under low-nutrient conditions. The native community also experienced a shift from more sensitive species, such as chlorophytes, to potentially more resilient species such as diatoms. The phytoplankton response to atrazine exposure at various concentrations can be especially important to greater trophic levels because their growth and abundance can determine the potential productivity of the entire ecosystem.

  5. Iron, phytoplankton growth, and the carbon cycle.

    Science.gov (United States)

    Street, Joseph H; Paytan, Adina

    2005-01-01

    Iron is an essential nutrient for all living organisms. Iron is required for the synthesis of chlorophyll and of several photosynthetic electron transport proteins and for the reduction of CO2, SO4(2-), and NO3(-) during the photosynthetic production of organic compounds. Iron concentrations in vast areas of the ocean are very low (iron in oxic seawater. Low iron concentrations have been shown to limit primary production rates, biomass accumulation, and ecosystem structure in a variety of open-ocean environments, including the equatorial Pacific, the subarctic Pacific and the Southern Ocean and even in some coastal areas. Oceanic primary production, the transfer of carbon dioxide into organic carbon by photosynthetic plankton (phytoplankton), is one process by which atmospheric CO2 can be transferred to the deep ocean and sequestered for long periods of time. Accordingly, iron limitation of primary producers likely plays a major role in the global carbon cycle. It has been suggested that variations in oceanic primary productivity, spurred by changes in the deposition of iron in atmospheric dust, control atmospheric CO2 concentrations, and hence global climate, over glacial-interglacial timescales. A contemporary application of this "iron hypothesis" promotes the large-scale iron fertilization of ocean regions as a means of enhancing the ability of the ocean to store anthropogenic CO2 and mitigate 21st century climate change. Recent in situ iron enrichment experiments in the HNLC regions, however, cast doubt on the efficacy and advisability of iron fertilization schemes. The experiments have confirmed the role of iron in regulating primary productivity, but resulted in only small carbon export fluxes to the depths necessary for long-term sequestration. Above all, these experiments and other studies of iron biogeochemistry over the last two decades have begun to illustrate the great complexity of the ocean system. Attempts to engineer this system are likely to

  6. Optogenetic control of ROS production

    Directory of Open Access Journals (Sweden)

    Andrew P. Wojtovich

    2014-01-01

    Full Text Available Reactive Oxygen Species (ROS are known to cause oxidative damage to DNA, proteins and lipids. In addition, recent evidence suggests that ROS can also initiate signaling cascades that respond to stress and modify specific redox-sensitive moieties as a regulatory mechanism. This suggests that ROS are physiologically-relevant signaling molecules. However, these sensor/effector molecules are not uniformly distributed throughout the cell. Moreover, localized ROS damage may elicit site-specific compensatory measures. Thus, the impact of ROS can be likened to that of calcium, a ubiquitous second messenger, leading to the prediction that their effects are exquisitely dependent upon their location, quantity and even the timing of generation. Despite this prediction, ROS signaling is most commonly intuited through the global administration of chemicals that produce ROS or by ROS quenching through global application of antioxidants. Optogenetics, which uses light to control the activity of genetically-encoded effector proteins, provides a means of circumventing this limitation. Photo-inducible genetically-encoded ROS-generating proteins (RGPs were originally employed for their phototoxic effects and cell ablation. However, reducing irradiance and/or fluence can achieve sub-lethal levels of ROS that may mediate subtle signaling effects. Hence, transgenic expression of RGPs as fusions to native proteins gives researchers a new tool to exert spatial and temporal control over ROS production. This review will focus on the new frontier defined by the experimental use of RGPs to study ROS signaling.

  7. Remote sensing of bio-optical water types, phytoplankton seasonality, and algal pigments in ocean margin waters

    Science.gov (United States)

    Bontempi, Paula Susan

    A frontal edge detection algorithm was applied to remotely sensed ocean color satellite data to identify incorrect retrievals of phytoplankton chl a concentrations, and refine estimates of primary producer abundance in bio-optically complex ocean margin waters. Improvement of the remotely sensed biological signal will facilitate establishment of more accurate daily to decadal phytoplankton spatial patterns in these waters, and enable prediction of phytoplankton blooms or features from space. Spatial patterns of chlorophyll a (chl a) and water-leaving radiance (Lwn) from 1998 SeaWiFS (Sea-Viewing Wide Field-of-View Sensor) images were examined from ocean margin waters off the southeastern continental United States (SEC). Ocean margin waters are bio-optically complex due to riverine input, terrestrial runoff, and associated dissolved and particulate materials. Dissolved and particulate materials affect water-leaving radiance values in regions of the electromagnetic spectrum (412, 443, 555 nm) where their absorption and scattering properties are strongest. The radiative signal of non chlorophyll-containing fractions is misinterpreted as chl a. Waters are bio-optically classified as dominated by phytoplankton and derivative products (Morel Case I), or non chlorophyll-containing in-water constituents (Morel Case II). An edge detection algorithm delineated bio-optical water masses. Spatial congruence of Lwn(555) and chl a fronts defined Case II waters, and residual chl a fronts identified Case I waters. Monthly phytoplankton spatial variability was examined during January, March, May, August, and November, representing major seasonal periods. Phytoplankton were associated with a shelf region based on their response to local physical forcings. River flow and wind stress affect inner shelf chl a distributions, while offshore chl a distributions are controlled by Gulf Stream meanders. Carolina Capes' oceanography influenced chl a frontal variability. Radiance data at 443nm

  8. Remote Sensing the Phytoplankton Seasonal Succession of the Red Sea

    KAUST Repository

    Raitsos, Dionysios E.

    2013-06-05

    The Red Sea holds one of the most diverse marine ecosystems, primarily due to coral reefs. However, knowledge on large-scale phytoplankton dynamics is limited. Analysis of a 10-year high resolution Chlorophyll-a (Chl-a) dataset, along with remotely-sensed sea surface temperature and wind, provided a detailed description of the spatiotemporal seasonal succession of phytoplankton biomass in the Red Sea. Based on MODIS (Moderate-resolution Imaging Spectroradiometer) data, four distinct Red Sea provinces and seasons are suggested, covering the major patterns of surface phytoplankton production. The Red Sea Chl-a depicts a distinct seasonality with maximum concentrations seen during the winter time (attributed to vertical mixing in the north and wind-induced horizontal intrusion of nutrient-rich water in the south), and minimum concentrations during the summer (associated with strong seasonal stratification). The initiation of the seasonal succession occurs in autumn and lasts until early spring. However, weekly Chl-a seasonal succession data revealed that during the month of June, consistent anti-cyclonic eddies transfer nutrients and/or Chl-a to the open waters of the central Red Sea. This phenomenon occurs during the stratified nutrient depleted season, and thus could provide an important source of nutrients to the open waters. Remotely-sensed synoptic observations highlight that Chl-a does not increase regularly from north to south as previously thought. The Northern part of the Central Red Sea province appears to be the most oligotrophic area (opposed to southern and northern domains). This is likely due to the absence of strong mixing, which is apparent at the northern end of the Red Sea, and low nutrient intrusion in comparison with the southern end. Although the Red Sea is considered an oligotrophic sea, sporadic blooms occur that reach mesotrophic levels. The water temperature and the prevailing winds control the nutrient concentrations within the euphotic zone

  9. 青草沙水库浮游藻类的调查及控制%Investigation and Control of Phytoplankton in Qingcaosha Reservoir

    Institute of Scientific and Technical Information of China (English)

    蒋增辉

    2012-01-01

    为预防和控制青草沙水库藻类大量增殖,在水库全面通水前(2011年1~6月)对浮游藻类进行调查,共检出8门80属,鉴定出124种/变种,出现频次较高的有梅尼小环藻、游丝藻、针晶蓝纤维藻、波吉卵囊藻、扁圆卵形藻等.水库进水中检出蓝藻9属、硅藻18属、绿藻14属、其他藻5属,水库内检出蓝藻14属、硅藻23属、绿藻27属、其他藻7属,库内种类比库外大幅增加.结果表明水库在发挥“避污蓄清”和“避咸蓄淡”功能时会导致库内水体流速减慢,有利于藻类增殖.并提出一系列藻类预警及监控措施.%To control and prevent the excessively proliferating of algae in Qingcaosha reservoir in Shanghai China, phytoplankton was investigated. A total of 8 phylum, 80 genera and 124 species (varieties) were identified. Among them, Cyclotella meneghiniana, Planctonema lauterbornii, Dactylococcopsis rhaphidioides, Oocystis borgei, Cocconeis placentula, etc, has higher frequency of occurrence. There were 9 genera of Cyanophyta, 18 genera of Bacillariophyta, 14 genera of Chlorophyta, 5 genera of other phylum identified in influent and 14 genera of Cyanophyta, 23 genera of Bacillariophyta, 27 genera of Chlorophyta, 5 genera of other phylum identified in the reservoir. The results show that while the function of avoiding saltwater and polluted water together with storing fresh and clean water is applied in the reservoir, reducing the flowing rate may promotes proliferating of algae. In addition, some special methods of monitoring, pre-warning, controlling of algae are put forward.

  10. Spatial and temporal dynamics of phytoplankton and bacterioplankton biomass in Sanya Bay, northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    ZHOU Weihua; LI Tao; XU Jirong; WANG Hankui; CAI Chuanghua; DONG Junde; ZHANG Si

    2009-01-01

    The composition of phytoplankton and the dynamics of phytoplankton and bacterioplankton biomass (PB and BB, respectively) of Sanya Bay, South China Sea, were determined. A total of 168 species (67 genera) phytoplankton were identified, including Bacillariophyta (diatom, 128 species), Pyrrophyta (35 species), Cyanophyta (3 species), and Chrysophyta (2 species). Annual average abundance of phytoplankton was 1.2 × 107 cells/m3, with the highest abundance in autumn, and the lowest in summer. Annual average diversity index (H′) and evenness (J) values were 3.86 and 0.70, respectively. Average chlorophyll a was 2.5 mg/m3, and the average PB was 124 mg C/m3, with the highest value in autumn. Surface PB was higher than the bottom, except for summer. Annual mean bacterioplankton abundance and BB were 6.9 × 1011 cells/m3 and 13.8 mg C/m3, respectively. The highest BB was found in summer, followed by winter, spring, and autumn. Surface BB was higher than bottom all year round. The spatial distribution patterns of PB and BB were very similar with the highest biomass in the estuary and decreasing seaward, primarily due to terrestrial input from the Sanya River and influx of oceanic water. The main factor influencing on PB and BB was DIN, with other factors such as temperature, which was above 22℃ throughout the year, having a negligible impact. The correlation between BB and PB was significant (P < 0.01). The annual average ratio of BB/PB was 0.12 (0.06--0.15). Phytoplankton primary production was one of the most important factors in controlling the distribution of bacterioplankton.

  11. Turbulent mixing, restratification, and phytoplankton growth at a submesoscale eddy

    Science.gov (United States)

    Taylor, J. R.

    2016-06-01

    High-resolution large-eddy simulations are used to study the influence of submesoscale mixed layer instability and small-scale turbulence on phytoplankton growth in light-limited conditions. Four simulations are considered with small-scale turbulence driven by varying levels of surface cooling. Significant small-scale turbulence is seen even without surface forcing, and the downward mixing of phytoplankton is sufficient to briefly delay the developing bloom. Moderate and strong values of the constant surface heat flux (Q =- 10,-100 W/m2) are sufficient to prevent a bloom. In contrast to the critical depth hypothesis, the growth rate for phytoplankton does not appear to be controlled by the mixed layer depth. Instead, a comparison between the turbulent diffusivity above the compensation depth and a critical value predicted by the critical turbulence hypothesis closely matches the timing and magnitude of phytoplankton growth.

  12. Revaluating ocean warming impacts on global phytoplankton

    Science.gov (United States)

    Behrenfeld, Michael J.; O'Malley, Robert T.; Boss, Emmanuel S.; Westberry, Toby K.; Graff, Jason R.; Halsey, Kimberly H.; Milligan, Allen J.; Siegel, David A.; Brown, Matthew B.

    2016-03-01

    Global satellite observations document expansions of the low-chlorophyll central ocean gyres and an overall inverse relationship between anomalies in sea surface temperature and phytoplankton chlorophyll concentrations. These findings can provide an invaluable glimpse into potential future ocean changes, but only if the story they tell is accurately interpreted. Chlorophyll is not simply a measure of phytoplankton biomass, but also registers changes in intracellular pigmentation arising from light-driven (photoacclimation) and nutrient-driven physiological responses. Here, we show that the photoacclimation response is an important component of temporal chlorophyll variability across the global ocean. This attribution implies that contemporary relationships between chlorophyll changes and ocean warming are not indicative of proportional changes in productivity, as light-driven decreases in chlorophyll can be associated with constant or even increased photosynthesis. Extension of these results to future change, however, requires further evaluation of how the multifaceted stressors of a warmer, higher-CO2 world will impact plankton communities.

  13. Reactivity of metals for marine phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, N.S.

    1986-03-01

    The concentration of metals by marine phytoplankton, assessed for diverse species in laboratory culture experiments with radiotracer methodology and taken together with literature values for other metals, was analyzed in light of geochemical models describing particle surface chemistry. Concentration factors vary among the metals from approx. ordered 0 to approx. ordered 10/sup 6/. Regression analyses show that, at equilibrium, the logs of the concentration factors are exponentially related to solubility products of metal hydroxides and to cytotoxicity and are linearly related to the log of the mean oceanic residence times (years) of the metals. It would appear that concentration factors and toxicity of metals in marine phytoplankton and oceanic residence times of metals can be predicted to within an order of magnitude from the chemical literature.

  14. Limnology in El Dorado: some surprising aspects of the regulation of phytoplankton productive capacity in a high-altitude Andean lake (Laguna de Guatavita, Colombia

    Directory of Open Access Journals (Sweden)

    Jhon Donato

    2012-09-01

    Full Text Available High-altitude mountain lakes remain understudied, mostly because of their relative inaccessibility. Laguna de Guatavita, a small, equatorial, high-altitude crater lake in the Eastern Range of the Colombian Andes, was once of high cultural importance to pre-Columban inhabitants, the original location of the legendary El Dorado. We investigated the factors regulating the primary production in Laguna de Guatavita (4°58’50” N - 73°46’43” W, alt. 2 935m.a.s.l., area: 0.11km², maximum depth: 30m, during a series of three intensive field campaigns, which were conducted over a year-long period in 2003-2004. In each, standard profiles of temperature, oxygen concentration and light intensity were determined on each of 16-18 consecutive days. Samples were collected and analysed for chlorophyll and for biologically-significant solutes in GF/F-filtered water (NH4+, NO3- , NO2-; soluble reactive phosphorus. Primary production was also determined, by oxygen generation, on each day of the campaign. Our results showed that the productive potential of the lake was typically modest (campaign averages of 45-90mg C/m².h but that many of the regulating factors were not those anticipated intuitively. The lake is demonstrably meromictic, reminiscent of karstic dolines in higher latitudes, its stratification being maintained by solute- concentration gradients. Light penetration is poor, attributable to the turbidity owing to fine calcite and other particulates in suspension. Net primary production in the mixolimnion of Laguna de Guavita is sensitive to day-to-day variations in solar irradiance at the surface. However, deficiencies in nutrient availability, especially nitrogen, also constrain the capacity of the lake to support a phytoplankton. We deduced that Laguna de Guatavita is something of a limnological enigma, atypical of the common anticipation of a “mountain lake”. While doubtlessly not unique, comparable descriptions of similar sites elsewhere

  15. Spectral effects in bio-optical control on the ocean system

    Directory of Open Access Journals (Sweden)

    Shubha Sathyendranath

    2007-03-01

    Full Text Available The influence of phytoplankton on the spectral structure of the submarine irradiance field is reviewed. The implications for the ocean system of the spectral response by phytoplankton to the ambient light field are discussed. For example, it provides the basis for retrieval of phytoplankton biomass by visible spectral radiometry (ocean-colour remote sensing. In the computation of primary production, the results of spectral models differ in a known and systematic manner from those of non-spectral ones. The bias can be corrected without risk of incurring additional random errors. The models in use for phytoplankton growth, whether based on available light or absorbed light, whether expressed in terms of chlorophyll or carbon, are shown all to conform to the same basic formalism with the same parameters. Residual uncertainty lies less with the models than with the parameters required for their implementation. The submarine light field and the spectral characteristics of phytoplankton carry latent information on phytoplankton community structure. Differences in spectral response by different functional types of phytoplankton are small but significant. Optical considerations limit the maximum phytoplankton biomass that can be sustained in a given surface mixed layer. Moreover, the upper bound on the biomass depends on the spectral response of the dominant phytoplankton taxa. As a result, an optical control exists in the mixed layer that tends to resist extreme excursions of the biomass and also to maintain biodiversity in the phytoplankton.

  16. Generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis.

    Science.gov (United States)

    Giometto, Andrea; Altermatt, Florian; Maritan, Amos; Stocker, Roman; Rinaldo, Andrea

    2015-06-02

    Phototaxis, the process through which motile organisms direct their swimming toward or away from light, is implicated in key ecological phenomena (including algal blooms and diel vertical migration) that shape the distribution, diversity, and productivity of phytoplankton and thus energy transfer to higher trophic levels in aquatic ecosystems. Phototaxis also finds important applications in biofuel reactors and microbiopropellers and is argued to serve as a benchmark for the study of biological invasions in heterogeneous environments owing to the ease of generating stochastic light fields. Despite its ecological and technological relevance, an experimentally tested, general theoretical model of phototaxis seems unavailable to date. Here, we present accurate measurements of the behavior of the alga Euglena gracilis when exposed to controlled light fields. Analysis of E. gracilis' phototactic accumulation dynamics over a broad range of light intensities proves that the classic Keller-Segel mathematical framework for taxis provides an accurate description of both positive and negative phototaxis only when phototactic sensitivity is modeled by a generalized "receptor law," a specific nonlinear response function to light intensity that drives algae toward beneficial light conditions and away from harmful ones. The proposed phototactic model captures the temporal dynamics of both cells' accumulation toward light sources and their dispersion upon light cessation. The model could thus be of use in integrating models of vertical phytoplankton migrations in marine and freshwater ecosystems, and in the design of bioreactors.

  17. Warming will affect phytoplankton differently: evidence through a mechanistic approach.

    Science.gov (United States)

    Huertas, I Emma; Rouco, Mónica; López-Rodas, Victoria; Costas, Eduardo

    2011-12-07

    Although the consequences of global warming in aquatic ecosystems are only beginning to be revealed, a key to forecasting the impact on aquatic communities is an understanding of individual species' vulnerability to increased temperature. Despite their microscopic size, phytoplankton support about half of the global primary production, drive essential biogeochemical cycles and represent the basis of the aquatic food web. At present, it is known that phytoplankton are important targets and, consequently, harbingers of climate change in aquatic systems. Therefore, investigating the capacity of phytoplankton to adapt to the predicted warming has become a relevant issue. However, considering the polyphyletic complexity of the phytoplankton community, different responses to increased temperature are expected. We experimentally tested the effects of warming on 12 species of phytoplankton isolated from a variety of environments by using a mechanistic approach able to assess evolutionary adaptation (the so-called ratchet technique). We found different degrees of tolerance to temperature rises and an interspecific capacity for genetic adaptation. The thermal resistance level reached by each species is discussed in relation to their respective original habitats. Our study additionally provides evidence on the most resistant phytoplankton groups in a future warming scenario.

  18. Phytoplankton Monitoring Network - Phytoplankton Analysis with Associated Collection Information

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A qualitative collection of data that includes salinity, temperature, phytoplankton counts and abundance ratios obtained from surface tows in the estuarine and...

  19. Bacterial survival governed by organic carbon release from senescent oceanic phytoplankton

    Directory of Open Access Journals (Sweden)

    S. Lasternas

    2013-10-01

    Full Text Available Bacteria recycle vast amounts of organic carbon, playing key biogeochemical and ecological roles in the ocean. Bacterioplankton dynamics are expected to be dependent on phytoplankton primary production, but there is a high diversity of processes (e.g. sloppy feeding, cell exudation, viral lysis involved in the transference of primary production to dissolved organic carbon available to bacteria. Here we show cell survival of heterotrophic bacterioplankton in the subtropical Atlantic Ocean to be determined by phytoplankton extracellular carbon release (PER. PER represents the fraction of primary production released as dissolved organic carbon, and changes in the PER variability was explained by phytoplankton cell death, with the communities experiencing the highest phytoplankton cell mortality showing a larger proportion of extracellular carbon release. Both PER and the percent of dead phytoplankton cells increased from eutrophic to oligotrophic waters, while heterotrophic bacteria communities, including 60 to 95% of living cells (%LC, increased from the productive to the most oligotrophic waters. The percentage of living heterotrophic bacterial cells increased with increasing phytoplankton extracellular carbon release, across oligotrophic to productive waters in the NE Atlantic, where lower PER have resulted in a decrease in the flux of phytoplankton DOC per bacterial cell. The results highlight phytoplankton cell death as a process influencing the flow of dissolved photosynthetic carbon in the NE Atlantic Ocean, and demonstrated a close coupling between the fraction of primary production released and heterotrophic bacteria survival.

  20. Development of Production Control in Small Batch Production

    Directory of Open Access Journals (Sweden)

    Németh Péter

    2016-01-01

    Full Text Available Our aim with this paper is to develop a new performance measurement and control system for small batch production in the automotive industry. For this reason, we present our previous research results for warehouse performance measurement and adopt its methodology to production control. The proposed method is based on artificial intelligence (neural networks.

  1. Robust Planning and Control Using Intelligent Products

    NARCIS (Netherlands)

    Meyer, Gerben; Wortmann, Johan; David, Esther; Gerding, Enrico; Sarne, David; Shehory, Onn

    2010-01-01

    The advances in production planning and control in the last decades have confirmed the centralized nature of the planning function. However, centralization has disadvantages when quick response to local production problems is required. Therefore, renewed interest in decentralized approaches emerges.

  2. Tilapia rendalli increases phytoplankton biomass of a shallow tropical lake

    Directory of Open Access Journals (Sweden)

    Lúcia Helena Sampaio da Silva

    2014-12-01

    Full Text Available AIM: This study aimed to experimentally test the influence of a planktivorous filter-feeding fish (Tilapia rendalli on the phytoplankton dynamics of a small and shallow tropical reservoir (Lake Monte Alegre, Brazil. Adults of T. rendalli of this lake feed preferentially on phytoplankton, and we hypothesize that: I adults of T. rendalli will decrease the phytoplankton biomass and composition through direct herbivory, and II as it is a eutrophic system, fish would not have strong influence on phytoplankton through nutrient cycling. METHODS: To evaluate these different effects on algae, a field experiment was performed in the summer period for 15 days, in mesocosms isolated from the sediment, using a control group (no fish and a treatment group (with one fish in each mesocosm. Physical and chemical variables and phyto- and zooplankton were evaluated at the start, middle, and end of the experiment. RESULTS: At the end of the experiment, it was observed a significant increase in ammonium concentrations and total phytoplankton biomass, Cyanobacteria and Zygnemaphyceae and all size classes except class II (20-30 µm in the treatment group (with fish. The biomass increase of the potentially toxic cyanobacterium Cylindrospermospsis raciborskii was also observed in the fish treatment at the end of the experimental period. CONCLUSION: This study did not support both initial hypotheses. It supports the assertion that in tropical water bodies, with similar characteristics to the environment studied, planktivorous filter-feeding fish, such as T. rendalli, are not effective in reducing phytoplankton biomass through direct grazing, even when phytoplankton is one of their main food items. T. rendalli can contribute to the increase of phytoplankton biomass and can promote or increase the eutrophication of aquatic systems.

  3. Glacial meltwater influences on plankton community structure and the importance of top-down control (of primary production) in a NE Greenland fjord

    Science.gov (United States)

    Arendt, Kristine Engel; Agersted, Mette Dalgaard; Sejr, Mikael Kristian; Juul-Pedersen, Thomas

    2016-12-01

    Freshwater runoff from the Greenland Ice Sheet (GIS) can be an important driver influencing plankton community structure in Greenland fjords. In the present study, we describe physical, taxonomic and functional differences in the plankton community in Young Sound, a NE Greenland fjord, from the inner fjord close to the GIS towards the coastal region in late summer. The fjord is influenced by runoff from land-terminating glaciers that separated the surface layer from cold underlying waters. The highest chlorophyll a concentration ( 74.9% of the total copepod biomass at all stations, and their grazing impact was the highest among the copepod groups. Copepod grazing impact on the phytoplankton standing stock, however, was exceeded by microzooplankton grazing, investigated by dilution experiments, with the highest grazing impact on the phytoplankton standing stock of 63% d-1 in the inner part of the fjord. In spite of high phytoplankton instantaneous growth rates at the innermost fjord station, proto-zooplankton was capable of controlling the phytoplankton production. The study showed functional differences within the system and provides indications of how dynamic the coastal ecosystem of Greenland can be.

  4. Impact of wastewater on phytoplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Jaiswar, M.J.R.

    A number of studies on phytoplankton were conducted by National Institute of Oceanography, Goa, India at Thane Creek, Maharashtra, India, Ulhas River estuary, Versova Creek and Mahim Creek under Coastal Ocean Monitoring and Prediction System (COMAPS...

  5. Phytoplankton depth profiles and their transitions near the critical sinking velocity.

    Science.gov (United States)

    Kolokolnikov, Theodore; Ou, Chunhua; Yuan, Yuan

    2009-07-01

    We consider a simple phytoplankton model introduced by Shigesada and Okubo which incorporates the sinking and self-shading effect of the phytoplankton. The amount of light the phytoplankton receives is assumed to be controlled by the density of the phytoplankton population above the given depth. We show the existence of non-homogeneous solutions for any water depth and study their profiles and stability. Depending on the sinking rate of the phytoplankton, light intensity and water depth, the plankton can concentrate either near the surface, at the bottom of the water column, or both, resulting in a "double-peak" profile. As the buoyancy passes a certain critical threshold, a sudden change in the phytoplankton profile occurs. We quantify this transition using asymptotic techniques. In all cases we show that the profile is locally stable. This generalizes the results of Shigesada and Okubo where infinite depth was considered.

  6. Changing nutrient stoichiometry affects phytoplankton production, DOP build up and dinitrogen fixation – a mesocosm experiment in the eastern tropical North Atlantic

    Directory of Open Access Journals (Sweden)

    J. Meyer

    2015-07-01

    Full Text Available 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 N : P ratio could reach the euphotic layer, possibly influencing primary production in those waters. Previous mesocosm studies in the oligotrophic Atlantic Ocean identified N availability as controlling of primary production, while a possible co-limitation of nitrate and phosphate (P could not be ruled out. To better understand the impact of changing N : P ratios on primary production and on 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. Silicate was supplied at 15 μmol L−1 in all mesocosms. We monitored nutrient drawdown, bloom formation, biomass build up and diazotrophic feedback in response to variable nutrient stoichiometry. Our results confirmed N to be limiting to primary production. We found that excess P was channeled through particulate organic matter (POP into the dissolved organic matter (DOP pool. In mesocosms with low P availability, DOP was utilized while N2 fixation increased, suggesting a link between those two processes. Interestingly this observation was most pronounced in mesocosms where inorganic N was still available, indicating that bioavailable N does not necessarily has to have a negative impact on N2 fixation. We observed a shift from a mixed cyanobacterial/proteobacterial dominated active diazotrophic community towards diazotrophic diatom symbionts of the Richelia-Rhizosolenia symbiosis. We hypothesize that a potential change in nutrient stoichiometry in the ETNA might lead to a general shift within the

  7. Automatic control algorithm effects on energy production

    Science.gov (United States)

    Mcnerney, G. M.

    1981-01-01

    A computer model was developed using actual wind time series and turbine performance data to simulate the power produced by the Sandia 17-m VAWT operating in automatic control. The model was used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long term energy production. The results from local site and turbine characteristics were generalized to obtain general guidelines for control algorithm design.

  8. Controls on the ratio of mesozooplankton production to primary production in marine ecosystems

    Science.gov (United States)

    Stock, Charles; Dunne, John

    2010-01-01

    An ecosystem model was used to (1) determine the extent to which global trends in the ratio of mesozooplankton production to primary production (referred to herein as the " z-ratio") can be explained by nutrient enrichment, temperature, and euphotic zone depth, and (2) quantitatively diagnose the mechanisms driving these trends. Equilibrium model solutions were calibrated to observed and empirically derived patterns in phytoplankton biomass and growth rates, mesozooplankton biomass and growth rates, and the fraction of phytoplankton that are large (>5 μm ESD). This constrained several otherwise highly uncertain model parameters. Most notably, half-saturation constants for zooplankton feeding were constrained by the biomass and growth rates of their prey populations, and low zooplankton basal metabolic rates were required to match observations from oligotrophic ecosystems. Calibrated model solutions had no major biases and produced median z-ratios and ranges consistent with estimates. However, much of the variability around the median values in the calibration dataset (72 points) could not be explained. Model results were then compared with an extended global compilation of z-ratio estimates (>10 000 points). This revealed a modest yet significant ( r=0.40) increasing trend in z-ratios from values ˜0.01-0.04 to ˜0.1-0.2 with increasing primary productivity, with the transition from low to high z-ratios occurring at lower primary productivity in cold-water ecosystems. Two mechanisms, both linked to increasing phytoplankton biomass, were responsible: (1) zooplankton gross growth efficiencies increased as their ingestion rates became much greater than basal metabolic rates and (2) the trophic distance between primary producers and mesozooplankton shortened as primary production shifted toward large phytoplankton. Mechanism (1) was most important during the transition from low to moderate productivity ecosystems and mechanism (2) was responsible for a relatively

  9. In situ study on photosynthetic characteristics of phytoplankton in the Yellow Sea and East China Sea in summer 2013

    Science.gov (United States)

    Li, Junlei; Sun, Xiaoxia; Zheng, Shan

    2016-08-01

    In situ studies on photosynthetic characteristics of phytoplankton were important for the analysis of changes in community structure and for the prediction and control of algal blooms, but such studies of phytoplankton in offshore China were few. In this study, the detailed distribution of photosynthetic characteristics of phytoplankton in the summer of 2013 in the Yellow Sea and East China Sea was measured using Phyto-PAM (Pulse Amplitude Modulation). The phytoplankton community structure and the environmental parameters were also investigated to estimate the relationship between the distribution of the photochemical competence of phytoplankton and ecological factors. The total average Fv/Fm (the potential maximum quantum yield) value of phytoplankton in the Yellow Sea and East China Sea in summer 2013 was less than 0.5, reflecting that the photosynthetic activity of phytoplankton was relatively low. Fv/Fm of phytoplankton in summer was significantly positively associated with nitrate content (NO2-), which reflects relationship between metabolism and photosynthesis of phytoplankton: accompanied by NO2- metabolism, photosynthesis and photosynthetic capacity may be enhanced simultaneously, so the Fv/Fm value would increase with the NO2- released by phytoplankton. Through the in situ study on photosynthetic characteristics of phytoplankton in the Yellow Sea and East China Sea, we come to the conclusion that photosynthetic characteristics and activity of phytoplankton are influenced by its biological characteristics and surrounding ecological factors, such as irradiance, nutrients and phytoplankton community. Meanwhile, the thermally stratified structure and the movement of water masses, such as the Yangtze River diluted water, the Yellow Sea cold water mass and other different water system, also have an important impact on phytoplankton photosynthetic activity and characteristics. Greater understanding of the detailed photosynthetic characteristics of phytoplankton

  10. Heterotrophic bacterial responses to the winter–spring phytoplankton bloom in open waters of the NW Mediterranean

    KAUST Repository

    Gomes, Ana

    2014-12-03

    The response of planktonic heterotrophic prokaryotes to the NW Mediterranean winter–spring offshore phytoplankton bloom was assessed in 3 cruises conducted in March, April–May and September 2009. Bulk measurements of phytoplankton and bacterioplankton biomass and production were complemented with an insight into bacterial physiological structure by single-cell analysis of nucleic acid content [low (LNA) vs. high (HNA)] and membrane integrity (“Live” vs. “Dead” cells). Bacterial production empirical conversion factors (0.82±0.25 SE kg C mol leucine−1) were almost always well below the theoretical value. Major differences in most microbial variables were found among the 3 periods, which varied from extremely high phytoplankton biomass and production during the bloom in March (>1 g C m−2 d−1 primary production) to typically oligotrophic conditions during September stratification (<200 mg C m−2 d−1). In both these periods bacterial production was ~30 mg C m−2 d−1 while very large bacterial production (mean 228, with some stations exceeding 500 mg C m−2 d−1) but low biomass was observed during the April–May post-bloom phase. The contribution of HNA (30–67%) and “Live” cells (47–97%) were temporally opposite in the study periods, with maxima in March and September, respectively. Different relationships were found between physiological structure and bottom-up variables, with HNA bacteria apparently more responsive to phytoplankton only during the bloom, coinciding with larger average cell sizes of LNA bacteria. Moderate phytoplankton–bacterioplankton coupling of biomass and activity was only observed in the bloom and post-bloom phases, while relationships between both compartments were not significant under stratification. With all data pooled, bacteria were only weakly bottom-up controlled. Our analyses show that the biomass and production of planktonic algae and bacteria followed opposite paths in the transition from bloom to

  11. Resolving variability of phytoplankton species composition and blooms in coastal ecosystems

    Science.gov (United States)

    Klais, Riina; Cloern, James E.; Harrison, Paul J.

    2015-09-01

    The contributions to this special volume focus on phytoplankton dynamics in coastal ecosystems, where perturbations from terrestrial, atmospheric, oceanic sources and human activities converge to cause changes in phytoplankton communities. Analyses of phytoplankton time series across the range of coastal sites, either as meta-analyses or single site based studies, complete our general understanding of the ecology of coastal phytoplankton dynamics. The role of short-term variability of the phytoplankton community appears to be more important for the annual primary production than previously thought, especially during the high biomass spring bloom period (Gallegos and Neale, 2015). Diel vertical migration of motile species is commonplace even in shallow and presumably well-mixed estuaries (Hall et al., 2015). Comparing phytoplankton patterns in various sites reveals contrasting long-term trends in the last two decades, reflecting the recent history of economic growth in related coastal areas. In Chesapeake Bay Estuary (US east coast) and Thau Lagoon (southern France), oligotrophication has been achieved by different nutrient reduction measures (Gowen et al., 2015; Harding et al., 2015), while in the Patos Lagoon Estuary (Brazil) and SE coast of Arabian Sea, the last two decades showed signs of eutrophication, following the more recent period of economic growth in the area (Haraguchi et al., 2015; Godhe et al., 2015). The global meta-analyses in this volume exposed the great challenges involved when working with this type of data, due to the diversity of idiosyncrasies characteristic to most phytoplankton time series, for example, the taxonomic practices, cell volume calculations (Harrison et al., 2015), volume to carbon conversions (Carstensen et al., 2015; Olli et al., 2015). But also the diversity of the patterns themselves makes analyses challenging (Carstensen et al., 2015; Thompson et al., 2015). To begin to move towards more similar practices in plankton

  12. Fe availability drives phytoplankton photosynthesis rates during spring bloom in the Amundsen Sea Polynya, Antarctica

    Directory of Open Access Journals (Sweden)

    Anne-Carlijn Alderkamp

    2015-04-01

    Full Text Available Abstract To evaluate what drives phytoplankton photosynthesis rates in the Amundsen Sea Polynya (ASP, Antarctica, during the spring bloom, we studied phytoplankton biomass, photosynthesis rates, and water column productivity during a bloom of Phaeocystis antarctica (Haptophyceae and tested effects of iron (Fe and light availability on these parameters in bioassay experiments in deck incubators. Phytoplankton biomass and productivity were highest (20 µg chlorophyll a L−1 and 6.5 g C m−2 d−1 in the central ASP where sea ice melt water and surface warming enhanced stratification, reducing mixed layer depth and increasing light availability. In contrast, maximum photosynthesis rate (P*max, initial light-limited slope of the photosynthesis–irradiance curve (α*, and maximum photochemical efficiency of photosystem II (Fv/Fm were highest in the southern ASP near the potential Fe sources of the Dotson and Getz ice shelves. In the central ASP, P*max, α*, and Fv/Fm were all lower. Fe addition increased phytoplankton growth rates in three of twelve incubations, and at a significant level when all experiments were analyzed together, indicating Fe availability may be rate-limiting for phytoplankton growth in several regions of the ASP early in the season during build-up of the spring bloom. Moreover, Fe addition increased P*max, α*, and Fv/Fm in almost all experiments when compared to unamended controls. Incubation under high light also increased P*max, but decreased Fv/Fm and α* when compared to low light incubation. These results indicate that the lower values for P*max, α*, and Fv/Fm in the central ASP, compared to regions close to the ice shelves, are constrained by lower Fe availability rather than light availability. Our study suggests that higher Fe availability (e.g., from higher melt rates of ice shelves would increase photosynthesis rates in the central ASP and potentially increase water column productivity 1.7-fold, making the ASP

  13. A model study on carbon cycle and phytoplankton dynamical processes in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    魏皓; 赵亮; 冯士筰

    2003-01-01

    The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimension-al biological and physical coupled model. The influences of the processes (including horizontal advection,river nutrient load, active transport etc. ) on the phytoplankton biomass and its evolution are estimated.The Bohai Sea is a weak sink of the CO2 in the atmosphere. During the cycle, 13.7% of the gross pro-duction of the phytoplankton enter the higher trophic level and 76.8 % of it are consumed by the respira-tion itself. The nutrient reproduction comes mainly from the internal biogeochemical loop and the rem-ineralization is an important mechanism of the nutrient transfer from organic form to inorganic. Horizon-tal advection decreases the total biomass and the eutrophication in some sea areas. Change in the nutrientload of a river can only adjust the local system near its estuary. Controlling the input of the nutrient,which limits the alga growth, can be very useful in lessening the phytoplankton biomass.

  14. An Improved Production Activity Control Architecture for Shop Floor Control

    Institute of Scientific and Technical Information of China (English)

    SHAHIDIkramullahButt; SUNHou-fang; HAMIDUllahKhanNiazi

    2005-01-01

    This paper presents a further improved Production Activity Control Architecture to deal with the complexity of information by creating Sub-Producers and Sub-Movers which will not only give a better control at workstation level but also reduce load on the Dispatcher. It also makes an analysis of the basic and improved PAC (Production Activity Control) Architecture in the Control System for Integrated Manufacturing. The PAC Architecture and the improvement will further enhance the flexibility and adaptability of the architecture in the ever changing environment of the Shop Floor Control (SFC) Systems.

  15. Studies on phytoplankton-bacterial interactions

    Digital Repository Service at National Institute of Oceanography (India)

    DeCosta, P.M.

    Given the sheer range of phytoplankton-bacterial interactions, some intriguing aspects have been addressed in this study. Firstly, the role of bacteria in influencing phytoplankton communities at the system level was examined. The seasonal changes...

  16. Phytoplankton community structure is influenced by seabird guano enrichment in the Southern Ocean

    Science.gov (United States)

    Shatova, O. A.; Wing, S. R.; Hoffmann, L. J.; Wing, L. C.; Gault-Ringold, M.

    2017-05-01

    Phytoplankton biomass, productivity and community structure are strongly influenced by differences in nutrient concentrations among oceanographic water masses. Changes in community composition, particularly in the distribution of cell sizes, can result in dramatic changes in the energetics of pelagic food webs and ecosystem function in terms of biogeochemical cycling and carbon sequestration. Here we examine responses of natural phytoplankton communities from four major water masses in the Southern Ocean to enrichment from seabird guano, a concentrated source of bioactive metals (Mn, Fe, Co, Ni, Cu, Zn) and macronutrients (N, P), in a series of incubation experiments. Phytoplankton communities from sub-tropical water, modified sub-tropical water from the Snares Island wake, sub-Antarctic water and Antarctic water from the Ross Sea, each showed dramatic changes in community structure following additions of seabird guano. We observed particularly high growth of prymnesiophytes in response to the guano-derived nutrients within sub-Antarctic and sub-tropical frontal zones, resulting in communities dominated by larger cell sizes than in control incubations. Community changes within treatments enriched with guano were distinct, and in most cases more extensive, than those observed for treatments with additions of macronutrients (N, P) or iron (Fe) alone. These results provide the first empirical evidence that seabird guano enrichment can drive significant changes in the structure and composition of natural phytoplankton communities. Our findings have important implications for understanding the consequences of accumulation of bioactive metals and macronutrients within food webs and the role of seabirds as nutrient vectors within the Southern Ocean ecosystem.

  17. Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems

    Science.gov (United States)

    Paerl, Hans; Yin, Kedong; Cloern, James

    2011-03-01

    Scientific Committee on Ocean Research Working Group 137 Meeting; Hangzhou, China, 17-21 October 2010; Phytoplankton biomass and community structure have undergone dramatic changes in coastal ecosystems over the past several decades in response to climate variability and human disturbance. These changes have short- and long-term impacts on global carbon and nutrient cycling, food web structure and productivity, and coastal ecosystem services. There is a need to identify the underlying processes and measure the rates at which they alter coastal ecosystems on a global scale. Hence, the Scientific Committee on Ocean Research (SCOR) formed Working Group 137 (WG 137), “Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems: A Comparative Analysis of Time Series Observations” (http://wg137.net/). This group evolved from a 2007 AGU-sponsored Chapman Conference entitled “Long Time-Series Observations in Coastal Ecosystems: Comparative Analyses of Phytoplankton Dynamics on Regional to Global Scales.”

  18. Microbiological Quality Control of Probiotic Products

    OpenAIRE

    Astashkina, Anna Pavlovna; Khudyakova, L. I.; Kolbysheva, Yuliya Vladimirovna

    2014-01-01

    Microbiological quality control of probiotic products such as Imunele, Dannon, Pomogayka showed that they contain living cultures of the Lactobacillus Bifidobacterium genus in the amount of 107 CFU/ml, which corresponds to the number indicated on the label of products. It is identified that the survival rate of test-strains cultured with pasteurized products does not exceed 10%. The cell concentration of target-microorganisms was reduced by 20-45% after the interaction with living probiotic b...

  19. Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Phytoplankton species composition and species succession were determined in 1998~1999 based on 2 nestle investigation cruises in the Bohai Sea and two monthly monitoring stations at Penglai and Changdao for 15 months. The seasonal succession and pathway of phytoplankton community in the Bohai Sea were discussed complementarily with history data. The main process of phytoplankton community development in the Bohai Sea was controlled by temperature and nutrient replenishes. There were two cell abundance peaks in an annual variation, the main peak in April and the secondary peak in September. In winter, the cell abundance was low due to the low temperature, the phytoplankton community was mainly made up of small-crled diatoms. In spring, the phytoplankton community was developed very quickly by small-celled diatom in suitable conditions of temperature and nutrients. In summer, the cell abundance decreased and big-celled diatoms became predominated. In autumn, because of the replenish of nutrient, big-celled diatoms and dinoflagellates formed another cell abundance peak.During the annual variation of phytoplankton community in the Bohai Sea, species succession was the main process of community development, the species sequence just occur at special areas and special periods. The evolution of phytoplankton community in the Bohai Sea accords with the hypothesis of Margalef's phytoplankton community of four stages. But the size feature is contrary to the hypothesis,which may be caused by nutrient replenish in autumn in Bohai Sea and the top to down control.

  20. Goniometer Control System for Coherent Bremsstrahlung Production

    Science.gov (United States)

    Acousta, V. M.

    2002-08-01

    A system for the generation of a high-intensity, quasi-monochromatic photon beam is discussed. The theory behind coherent bremsstrahlung photon beam production is analyzed and developed. The mechanics of a goniometer control system are presented. The software developed for remote control of the goniometer is also discussed. Finally, the results from various performance measurements are included.

  1. Toxicity of atmospheric aerosols on marine phytoplankton

    Science.gov (United States)

    Paytan, A.; Mackey, K.R.M.; Chen, Y.; Lima, I.D.; Doney, S.C.; Mahowald, N.; Labiosa, R.; Post, A.F.

    2009-01-01

    Atmospheric aerosol deposition is an important source of nutrients and trace metals to the open ocean that can enhance ocean productivity and carbon sequestration and thus influence atmospheric carbon dioxide concentrations and climate. Using aerosol samples from different back trajectories in incubation experiments with natural communities, we demonstrate that the response of phytoplankton growth to aerosol additions depends on specific components in aerosols and differs across phytoplankton species. Aerosol additions enhanced growth by releasing nitrogen and phosphorus, but not all aerosols stimulated growth. Toxic effects were observed with some aerosols, where the toxicity affected picoeukaryotes and Synechococcus but not Prochlorococcus.We suggest that the toxicity could be due to high copper concentrations in these aerosols and support this by laboratory copper toxicity tests preformed with Synechococcus cultures. However, it is possible that other elements present in the aerosols or unknown synergistic effects between these elements could have also contributed to the toxic effect. Anthropogenic emissions are increasing atmospheric copper deposition sharply, and based on coupled atmosphere-ocean calculations, we show that this deposition can potentially alter patterns of marine primary production and community structure in high aerosol, low chlorophyll areas, particularly in the Bay of Bengal and downwind of South and East Asia.

  2. Title: Freshwater phytoplankton responses to global warming.

    Science.gov (United States)

    Wagner, Heiko; Fanesi, Andrea; Wilhelm, Christian

    2016-09-20

    Global warming alters species composition and function of freshwater ecosystems. However, the impact of temperature on primary productivity is not sufficiently understood and water quality models need to be improved in order to assess the quantitative and qualitative changes of aquatic communities. On the basis of experimental data, we demonstrate that the commonly used photosynthetic and water chemistry parameters alone are not sufficient for modeling phytoplankton growth under changing temperature regimes. We present some new aspects of the acclimation process with respect to temperature and how contrasting responses may be explained by a more complete physiological knowledge of the energy flow from photons to new biomass. We further suggest including additional bio-markers/traits for algal growth such as carbon allocation patterns to increase the explanatory power of such models. Although carbon allocation patterns are promising and functional cellular traits for growth prediction under different nutrient and light conditions, their predictive power still waits to be tested with respect to temperature. A great challenge for the near future will be the prediction of primary production efficiencies under the global change scenario using a uniform model for phytoplankton assemblages. Copyright © 2016 Elsevier GmbH. All rights reserved.

  3. Network-based production quality control

    Science.gov (United States)

    Kwon, Yongjin; Tseng, Bill; Chiou, Richard

    2007-09-01

    This study investigates the feasibility of remote quality control using a host of advanced automation equipment with Internet accessibility. Recent emphasis on product quality and reduction of waste stems from the dynamic, globalized and customer-driven market, which brings opportunities and threats to companies, depending on the response speed and production strategies. The current trends in industry also include a wide spread of distributed manufacturing systems, where design, production, and management facilities are geographically dispersed. This situation mandates not only the accessibility to remotely located production equipment for monitoring and control, but efficient means of responding to changing environment to counter process variations and diverse customer demands. To compete under such an environment, companies are striving to achieve 100%, sensor-based, automated inspection for zero-defect manufacturing. In this study, the Internet-based quality control scheme is referred to as "E-Quality for Manufacturing" or "EQM" for short. By its definition, EQM refers to a holistic approach to design and to embed efficient quality control functions in the context of network integrated manufacturing systems. Such system let designers located far away from the production facility to monitor, control and adjust the quality inspection processes as production design evolves.

  4. Short-term variations of phytoplankton communities in response to anthropogenic stressors in a highly altered temperate estuary

    Science.gov (United States)

    Sin, Yongsik; Jeong, Byungkwan

    2015-04-01

    Data for phytoplankton size classes, taxonomy, and water properties were collected through an episodic freshwater discharge event (4 days) in the temperate Youngsan River estuary, which is highly disturbed by manually regulated inputs of freshwater from a sea dike, to investigate the effects of an acute change in anthropogenic stressors on the short-term dynamics of phytoplankton and their surrounding environments. The salinity of the well-mixed saline water (33.2-33.5) decreased to as low as 4.0 and water temperature increased to 24.0 °C during the freshwater discharge, resulting in a stratified water column in the upper region of the estuary. During the discharge, chlorophyll a (chl a) concentrations increased to as much as 15.66 μg L-1 with micro-sized phytoplankton being dominant due to the presence of micro-sized freshwater phytoplankton, mostly Aulacoseira ambigua (98% in cell abundance), transported from the reservoir. Primary production decreased to as little as 87.9 mg C m-2 d-1, although nutrients such as NO2- + NO3- were supplied by the freshwater inputs of the discharge. Following the discharge, dinoflagellate blooms, dominated by Heterocapsa sp. (>88%), a nano-sized red tide species, developed in the upper regions of the estuary with peaks in chl a concentrations reaching as high as 30.33 μg L-1. Another red tide species, Prorocentrum micans, was also dominant in the estuary, suggesting that harmful algal blooms (HABs) are associated with anthropogenic stressors related to the freshwater inputs. The Shannon diversity index decreased to 0.18 while the Simpson dominance index increased to 0.94 during the discharge, but the diversity increased again following the discharge. The phytoplankton communities and diversity changed along the salinity gradient, corresponding to an "ecocline" pattern. The results of multivariate statistical analysis suggested that phytoplankton species and size structure were controlled mainly by salinity, water temperature

  5. Influence of Seawater Temperature on Phytoplankton Growth in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    杨东方; 高振会; 陈豫; 王培刚; 孙培艳

    2004-01-01

    The phytoplankton reproduction capacity (PRC), as a new concept regarding chlorophyll-a and primary production (PP) is described. PRC is different from PP, carbon assimilation number (CAN) or photosynthetic rate (PB). PRC quantifies phytoplankton growth with a special consideration of the effect of seawater temperature. Observation data in Jiaozhou Bay, Qingdao, China, collected from May 1991 to February 1994 were used to analyze the horizontal distribution and seasonal variation of the PRC in Jiaozhou Bay in order to determine the characteristics, dynamic cycles and trends of phytoplankton growth in Jiaozhou Bay; and to develop a corresponding dynamic model of seawater temperature vs. PRC. Simulation curves showed that seawater temperature has a dual function of limiting and enhancing PRC. PRC's periodicity and fluctuation are similar to those of the seawater temperature. Nutrient silicon in Jiaozhou Bay satisfies phytoplankton growth from June 7 to November 3. When nutrients N, P and Si satisfy the phytoplankton growth and solar irradiation is sufficient, the PRC would reflect the influence of seawater temperature on phytoplankton growth. Moreover, the result quantitatively explains the scenario of one-peak or two-peak phytoplankton reproduction in Jiaozhou Bay, and also quantitatively elucidates the internal mechanism of the one- or two-peak phytoplankton reproduction in the global marine areas.

  6. Modern control of mineral wool production process

    Directory of Open Access Journals (Sweden)

    Stankov Stanko P.

    2013-01-01

    Full Text Available In this paper, the control of the plant for mineral wool production consisting of a number of the technological units of different sizes and complexity is considered. The application of modern equipment based on PLC (Programmable Logic Controller and SCADA (Supervisory Control And Data Acquisition configuration provides optimal control of technological process. Described supervisory and control system is consisting of a number of units doing decentralized distributed control of technological entities where all possible situation are considered during work of machines and devices, which are installed in electric drive and are protected from technological and electrical accident. Transformer station and diesel engine, raw materials transport and dosage, processes in dome oven, centrifuges, polycondensation (PC chamber, burners, compressor station, binder preparation and dosage, wool cutting, completed panel packing and their transport to storehouse are controlled. Process variables and parameters like as level, flow, velocity, temperature, pressure, etc. are controlled. Control system is doing identification of process states changes, diagnostic and prediction of errors and provides prediction of behavior of control objects when input flows of materials and generates optimal values of control variables due to decreasing downtime and technic - economical requires connected to wool quality to be achieved. Supervisory and control system either eliminates unwanted changes in the production line or restricts them within the allowable limits according to the technology. In this way, the optimization of energy and raw materials consumption and appropriate products quality is achieved, where requirements are satisfied in accordance with process safety and environmental standards. SCADA provides a visual representation of controlled and uncontrolled parts of the technological process, processing alarms and events, monitoring of the changes of relevant

  7. Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

    Institute of Scientific and Technical Information of China (English)

    MINU P; SHAJU S S; MUHAMED ASHRAF P; MEENAKUMARI B

    2014-01-01

    Remote sensing applications are important in the fisheries sector and efforts were on to improve the predic-tions of potential fishing zones using ocean color. The present study was aimed to investigate the phyto-plankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×103 to 55.075×106 cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera asSkeletonemaspp.,Planktionellaspp.andThalassiosiraspp. Annual variations in abun-dance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophylla, Chlorophyllb, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin,β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.

  8. A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

    Directory of Open Access Journals (Sweden)

    K. Fennel

    2011-07-01

    Full Text Available The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer, but the mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. Unraveling these interactions will have to rely on a combination of observations and models. Here we present results from a realistic, 3-dimensional, physical-biological model with focus on a quantification of nutrient-stimulated phytoplankton growth, its variability and the fate of this organic matter. We demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input, and find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes.

  9. Basin-scale spatio-temporal variability and control of phytoplankton photosynthesis in the Baltic Sea: The first multiwavelength fast repetition rate fluorescence study operated on a ship-of-opportunity

    Science.gov (United States)

    Houliez, Emilie; Simis, Stefan; Nenonen, Susanna; Ylöstalo, Pasi; Seppälä, Jukka

    2017-05-01

    This study presents the results of the first field application of a flow-through multi-wavelength Fast Repetition Rate fluorometer (FRRF) equipped with two excitation channels (458 and 593 nm). This device aims to improve the measurement of mixed cyanobacteria and algae community's photosynthetic parameters and was designed to be easily incorporated into existing ferrybox systems. We present a spatiotemporal analysis of the maximum photochemical efficiency (Fv/Fm) and functional absorption cross section (σPSII) recorded from April to August 2014 on a ship-of-opportunity commuting twice per week between Helsinki (Finland) and Travemünde (Germany). Temporal variations of Fv/Fm and σPSII differed between areas of the Baltic Sea. However, even though the Baltic Sea is characterized by several physico-chemical gradients, no gradient was observed in Fv/Fm and σPSII spatial distribution suggesting complex interactions between biotic and abiotic controls. σPSII was sensitive to phytoplankton seasonal succession and thus differed according to the wavelength used to excite photosystems II (PSII) pigments. This was particularly true in summer when high σPSII(593) values were observed later and longer than high σPSII(458) values, reflecting the role of cyanobacteria in photosynthetic light uptake measured at community scale. In contrast, Fv/Fm variations were similar after excitation at 458 nm or 593 nm suggesting that the adjustment of Fv/Fm in response to environmental factors was similar for the different groups (algae vs. cyanobacteria) present within the phytoplankton community.

  10. Satellite and ship studies of phytoplankton along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Gomes, H.; Kumar, A; Gouveia, A; Devassy, V.P.; Parulekar, A; Rao, L.V.G.

    AidEd. by a sequence of chlorophyll images from the Coastal Zone Color Scanner on board the Nimbus-7 satellite and extensive shipboard observations, a descriptive analysis of the factors influencing the distribution and production of phytoplankton...

  11. Latitudinal phytoplankton distribution and the neutral theory of biodiversity

    KAUST Repository

    Chust, Guillem

    2012-11-16

    Recent studies have suggested that global diatom distributions are not limited by dispersal, in the case of both extant species and fossil species, but rather that environmental filtering explains their spatial patterns. Hubbell\\'s neutral theory of biodiversity provides a framework in which to test these alternatives. Our aim is to test whether the structure of marine phytoplankton (diatoms, dinoflagellates and coccolithophores) assemblages across the Atlantic agrees with neutral theory predictions. We asked: (1) whether intersite variance in phytoplankton diversity is explained predominantly by dispersal limitation or by environmental conditions; and (2) whether species abundance distributions are consistent with those expected by the neutral model. Location: Meridional transect of the Atlantic (50° N-50° S). Methods: We estimated the relative contributions of environmental factors and geographic distance to phytoplankton composition using similarity matrices, Mantel tests and variation partitioning of the species composition based upon canonical ordination methods. We compared the species abundance distribution of phytoplankton with the neutral model using Etienne\\'s maximum-likelihood inference method. Results: Phytoplankton communities are slightly more determined by niche segregation (24%), than by dispersal limitation and ecological drift (17%). In 60% of communities, the assumption of neutrality in species\\' abundance distributions could not be rejected. In tropical zones, where oceanic gyres enclose large stable water masses, most communities showed low species immigration rates; in contrast, we infer that communities in temperate areas, out of oligotrophic gyres, have higher rates of species immigration. Conclusions: Phytoplankton community structure is consistent with partial niche assembly and partial dispersal and drift assembly (neutral processes). The role of dispersal limitation is almost as important as habitat filtering, a fact that has been

  12. The use of the stable isotope, oxygen-18, as a tracer to measure gross primary production in coastal and oligotrophic waters and in monoclonal cultures of marine phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Grande, K.D.

    1988-01-01

    A new technique was developed to measure the in vitro rates of gross oxygen production in planktonic communities, in which water is enriched with the stable isotope {sup 18}O, and photosynthetic evolution of {sup 18}O{sup 16}O is measured. In order to calculate gross oxygen production, they correct for the {sup 18}O fractionation due to respiration. The standard technique for measuring production in the oceans, {sup 14}C-bicarbonate uptake, has recently been questioned due to discrepancies with other estimates of water column production and suspected intrinsic problems with the {sup 14}C technique. They compared rates of {sup 18}O gross production and {sup 14}C production in oligotrophic and coastal sites. Samples were generally incubated under natural lighting with neutral density screening. Some oligotrophic bottles were incubated in situ at the depth of collection. Rates of {sup 14}C production were 60-100% of {sup 18}O gross production in both coastal and oceanic communities. Assuming a PQ of 1.0 to 1.5, these comparisons suggest that {sup 14}C production rates are not seriously underestimating actual in vitro rates of production. They also measured rates of light respiration in cultures and natural populations by the {sup 18}O technique. The rates of light respiration in algal cultures were generally greater than dark rates by a factor of two to ten. The increased respiration in the light could be due to increased rates of mitochondrial respiration, photorespiration or Mehler respiration. They measured the enhanced {sup 14}C production under reduced (O{sub 2}) conditions (the Warburg effect), as an estimate of the rate of photorespiration. In three clones, rates of photorespiration were a significant fraction of light respiration. In five other clones examined, photorespiration was not implicated as a source of light respiration.

  13. Exploring the link between micro-nutrients and phytoplankton in the Southern Ocean during the 2007 austral summer

    Directory of Open Access Journals (Sweden)

    Christel eHassler

    2012-07-01

    Full Text Available Bottle assays and large-scale fertilisation experiments have demonstrated that, in the Southern Ocean, iron often controls the biomass and the biodiversity of primary producers. To grow, phytoplankton need numerous other trace metals (micronutrients required for the activity of key enzymes and other intracellular functions. However, little is known of the potential these other trace elements have to limit the growth of phytoplankton in the Southern Ocean. This study investigates the link between the distribution of several micronutrients (Zn, Co, Cu, Cd, Ni and phytoplankton from samples collected during the SAZ-Sense oceanographic expedition (RV Aurora Australis, Jan.–Feb. 2007. Larger phytoplankton are usually associated with lower diffusive supply and higher micronutrient requirement; for this reason, the delineation between phytoplankton larger than 10 µm and those with a size ranging from 0.8–10 µm was made. In addition, different species of phytoplankton may have different requirements to sustain their growth; the phytoplankton biodiversity here was inferred using biomarker pigments. This study, therefore, attempts to elucidate whether micronutrients other than iron need to be considered as parameters for controlling the phytoplankton growth in the Australian sector of the Southern Ocean. Understanding of the parameters controlling phytoplankton is paramount, as it affects the functioning of the Southern Ocean, its marine resources and ultimately the global carbon cycle.

  14. Management Control in New Product Development

    DEFF Research Database (Denmark)

    Jørgensen, Brian; Messner, Martin

    2009-01-01

    Several studies in management control have drawn upon the concepts of coercive and enabling forms of bureaucracy (Adler and Borys 1996) to discuss how the features of a control system may affect employees' attitudes toward control. This question is relevant because enabling forms of control allow...... organizations to better manage tensions between efficiency and flexibility, which is arguably a key issue in many organizations today. Our paper contributes to this stream of research by detailing how enabling control functions in the particular setting of new product development. To this end, we draw upon...... empirical material collected through an in-depth field study carried out in a manufacturing organization. We use data from interviews, participant observation, and internal documentation in this firm to demonstrate how the combination of different control mechanisms helps the organization balance efficiency...

  15. Decision Support for effective production control

    DEFF Research Database (Denmark)

    Africa, E.; Nehzati, T.; Strandhagen, J.O.;

    2012-01-01

    This study aims to identify the actual needs of decision makers for decision support in the production control activity, considering the role and cognitive skills of human decision-makers in the decision-making process. Multiple case studies have been conducted in order to gain practical insights...

  16. Internal transport control in pot plant production

    NARCIS (Netherlands)

    Annevelink, E.

    1999-01-01

    Drawing up internal transport schedules in pot plant production is a very complex task. Scheduling internal transport at the operational level and providing control on a day-to-day or even hour-to-hour basis in particular requires a new approach. A hierarchical planning approach based on

  17. Control of primary production in the Arctic by nutrients and light: insights from a high resolution ocean general circulation model

    Directory of Open Access Journals (Sweden)

    E. E. Popova

    2010-07-01

    Full Text Available Until recently, the Arctic Basin was generally considered to be a low productivity area and was afforded little attention in global- or even basin-scale ecosystem modelling studies. Due to anthropogenic climate change however, the sea ice cover of the Arctic Ocean is undergoing an unexpectedly fast retreat, exposing increasingly large areas of the basin to sunlight. As indicated by existing Arctic phenomena such as ice-edge blooms, this decline in sea-ice is liable to encourage pronounced growth of phytoplankton in summer and poses pressing questions concerning the future of Arctic ecosystems. It thus provides a strong impetus to modelling of this region.

    The Arctic Ocean is an area where plankton productivity is heavily influenced by physical factors. As these factors are strongly responding to climate change, we analyse here the results from simulations of the 1/4° resolution global ocean NEMO (Nucleus for European Modelling of the Ocean model coupled with the MEDUSA (Model for Ecosystem Dynamics, carbon Utilisation, Sequestration and Acidification biogeochemical model, with a particular focus on the Arctic Basin. Simulated productivity is consistent with the limited observations for the Arctic, with significant production occurring both under the sea-ice and at the thermocline, locations that are difficult to sample in the field.

    Results also indicate that a substantial fraction of the variability in Arctic primary production can be explained by two key physical factors: (i the maximum penetration of winter mixing, which determines the amount of nutrients available for summer primary production, and (ii short-wave radiation at the ocean surface, which controls the magnitude of phytoplankton blooms. A strong empirical correlation was found in the model output between primary production these two factors, highlighting the importance of physical processes in the Arctic Ocean.

  18. A Projection of Automated Book Production Control

    Directory of Open Access Journals (Sweden)

    Mario Barisic

    2006-12-01

    Full Text Available The paper elaborates on the recommendation of systematic introducing of XML technologies as a standard and integral factor in publishing and graphic business activities and as a further improvement of the existing PostScript graphic production platform. Procedures are proposed for applying norm setting in respect to production processes through related connections organized databases under XML technology in a hierarchical way, as well as a book production norm setting system. The proposal for work processes automation in the domain of printing business control is elaborated under the CIP4-JDF automating system. Operation results are used as guidelines for setting the elements of automated business operations in the book production domain, with integrated elements of new technologies, compatible with global trends.

  19. Robust Planning and Control Using Intelligent Products

    Science.gov (United States)

    Meyer, Gerben G.; Wortmann, J. C. (Hans)

    The advances in production planning and control in the last decades have confirmed the centralized nature of the planning function. However, centralization has disadvantages when quick response to local production problems is required. Therefore, renewed interest in decentralized approaches emerges. This paper investigates the possibility to use intelligent products for decentralized handling of disturbances. Intelligent products are aware of their local context and they can negotiate with local manufacturing resources. Therefore, local solutions for problems can be suggested, virtually at the same time at which the problem occurs. The paper demonstrates the viability of this approach via a simulation study. For reasons of comparison, the TAC SCM environment is used. Moreover, robustness is taken as an additional measurement of performance. The results of the simulations are encouraging.

  20. Phytoplankton diversity of the Gharni Reservoir in Latur district, Maharashtra, India

    Directory of Open Access Journals (Sweden)

    Vishwas Balasaheb Sakhare

    2015-08-01

    Full Text Available The phytoplanktonic samples were collected from the Gharni Reservoir of Latur district of Maharashtra for a period of one year, from June 2013 to May 2014. Totally 18 species of phytoplankton belonging to different taxonomic groups were identified. Among these 7 species belong to Chlorophyceae, 5 species to Cyanophyceae, 3 species to Bacillariophyceae and 3 species to Euglenophyceae. The phytoplankton productivity fluctuated seasonally and the maximum number of 560 units/liter was recorded during month of February and March and minimum number of 95 units/liter during the month of September.

  1. Warming accelerates termination of a phytoplankton spring bloom by fungal parasites

    NARCIS (Netherlands)

    Frenken, Thijs; Velthuis, M.; De Senerpont Domis, Lisette; Stephan, Susanne; Aben, Ralf Cornelis; Kosten, S.; van Donk, E.; Van de Waal, D.B.

    2016-01-01

    Climate change is expected to favour infectious diseases across ecosystems worldwide. In freshwater and marine environments, parasites play a crucial role in controlling plankton population dynamics. Infection of phytoplankton populations will cause a transfer of carbon and nutrients into parasites,

  2. Management Control in New Product Development

    DEFF Research Database (Denmark)

    Jørgensen, Brian; Messner, Martin

    2009-01-01

    organizations to better manage tensions between efficiency and flexibility, which is arguably a key issue in many organizations today. Our paper contributes to this stream of research by detailing how enabling control functions in the particular setting of new product development. To this end, we draw upon......Several studies in management control have drawn upon the concepts of coercive and enabling forms of bureaucracy (Adler and Borys 1996) to discuss how the features of a control system may affect employees' attitudes toward control. This question is relevant because enabling forms of control allow...... that these repair efforts are perceived as not wholly satisfactory, which suggests that, in the case of important strategic changes, repair may require more top-down management intervention....

  3. Photoadaptation in Marine Phytoplankton 1

    Science.gov (United States)

    Neori, Amir; Holm-Hansen, Osmund; Mitchell, B. Greg; Kiefer, Dale A.

    1984-01-01

    The optical properties of marine phytoplankton were examined by measuring the absorption spectra and fluorescence excitation spectra of chlorophyll a for natural marine particles collected on glass fiber filters. Samples were collected at different depths from stations in temperate waters of the Southern California Bight and in polar waters of the Scotia and Ross Seas. At all stations, phytoplankton fluorescence excitation and absorption spectra changed systematically with depth and vertical stability of the water columns. In samples from deeper waters, both absorption and chlorophyll a fluorescence excitation spectra showed enhancement in the blue-to-green portion of the spectrum (470-560 nm) relative to that at 440 nm. Since similar changes in absorption and excitation were induced by incubating sea water samples at different light intensities, the changes in optical properties can be attributed to photoadaptation of the phytoplankton. The data indicate that in the natural populations studied, shade adaptation caused increases in the concentration of photosynthetic accessory pigments relative to chlorophyll a. These changes in cellular pigment composition were detectable within less than 1 day. Comparisons of absorption spectra with fluorescence excitation spectra indicate an apparent increase in the efficiency of sensitization of chlorophyll a fluorescence in the blue and green spectral regions for low light populations. PMID:16663873

  4. Phytoplankton community structure at the juncture of the Agulhas return front and subtropical front in the Indian Ocean sector of Southern Ocean: Bottom-up and top-down control

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, R.K.; George, J.V.; Soares, M.A.; Devi, A.; Anilkumar, N.; Roy, R.; Bhaskar, P.V.; Murukesh, N.; Achuthankutty, C.T.

    The juncture of the Agulhas Return Front (ARF) and Subtropical Front (STF) in the Indian Ocean sector of Southern Ocean (SO) is characterized by high mesoscale turbulence, which results in sporadic, short lived phytoplankton proliferation The biota...

  5. Mechanics of human voice production and control

    Science.gov (United States)

    Zhang, Zhaoyan

    2016-01-01

    As the primary means of communication, voice plays an important role in daily life. Voice also conveys personal information such as social status, personal traits, and the emotional state of the speaker. Mechanically, voice production involves complex fluid-structure interaction within the glottis and its control by laryngeal muscle activation. An important goal of voice research is to establish a causal theory linking voice physiology and biomechanics to how speakers use and control voice to communicate meaning and personal information. Establishing such a causal theory has important implications for clinical voice management, voice training, and many speech technology applications. This paper provides a review of voice physiology and biomechanics, the physics of vocal fold vibration and sound production, and laryngeal muscular control of the fundamental frequency of voice, vocal intensity, and voice quality. Current efforts to develop mechanical and computational models of voice production are also critically reviewed. Finally, issues and future challenges in developing a causal theory of voice production and perception are discussed. PMID:27794319

  6. Light utilization and photoinhibition of photosynthesis in marine phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Falkowski, P.G., Greene, R., Kolber, Z.

    1993-12-31

    Introduction to Phytoplankton. Based on the record of the oldest identifiable fossils, the first oxygenic photosynthetic organisms appeared about 2 {times} l0{sup 9} years ago in the form of marine single celled, planktonic procaryotes (Riding, 1992; Sarmiento and Bender, 1993). In the intervening eons, phytoplankton have evolved and diversified; presently they represent at least 11 classes of procaryotic and euacaryotic photoautotrophs. While the carbon of these organisms cumulatively amounts to only 1 to 2% of the global plant biomass, they fix between 35 and 50 gigatonnes ({times} 10{sup 9} metric tons) of carbon annually, about 40% of the global total (Falkowski and Woodhead, 1992). On average, each gram of phytoplankton chlorophyll converts about 6% of the photosynthetically active radiation (440 to 700 nm) incident on the sea surface to photochemical energy (Morel, 1978). Despite a great deal of variability in ocean environments, this photosynthetic conversion efficiency is relatively constant for integrated water column production (Morel, 1978; Falkowski, 1981; Platt, 1986; Morel, 1991). Here we review the factors determining light utilization efficiency of phytoplankton in the oceans, and the physiological acclimations which have evolved to optimize light utilization efficiency.

  7. What is causing the phytoplankton increase in San Francisco Bay?

    Science.gov (United States)

    Cloern, J.E.; Jassby, A.D.; Schraga, T.S.; Dallas, K.L.

    2006-01-01

    The largest living component of San Francisco Bay is the phytoplankton, a suspension of microscopic cells that convert sunlight energy into new living biomass through the same process of photosynthesis used by land plants. This primary production is the ultimate source of food for clams, zooplankton, crabs, sardines, halibut, sturgeon, diving ducks, pelicans, and harbor seals. From measurements made in 1980, we estimated that phytoplankton primary production in San Francisco Bay was about 200,000 tons of organic carbon per year (Jassby et al. 1993). This is equivalent to producing the biomass of 5500 adult humpback whales, or the calories to feed 1.8 million people. These numbers may seem large, but primary production in San Francisco Bay is low compared to many other nutrient-enriched estuaries.

  8. Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms.

    Directory of Open Access Journals (Sweden)

    Presentación Carrillo

    Full Text Available Some of the most important effects of global change on coastal marine systems include increasing nutrient inputs and higher levels of ultraviolet radiation (UVR, 280-400 nm, which could affect primary producers, a key trophic link to the functioning of marine food webs. However, interactive effects of both factors on the phytoplankton community have not been assessed for the Mediterranean Sea. An in situ factorial experiment, with two levels of ultraviolet solar radiation (UVR+PAR vs. PAR and nutrients (control vs. P-enriched, was performed to evaluate single and UVR×P effects on metabolic, enzymatic, stoichiometric and structural phytoplanktonic variables. While most phytoplankton variables were not affected by UVR, dissolved phosphatase (APAEX and algal P content increased in the presence of UVR, which was interpreted as an acclimation mechanism of algae to oligotrophic marine waters. Synergistic UVR×P interactive effects were positive on photosynthetic variables (i.e., maximal electron transport rate, ETRmax, but negative on primary production and phytoplankton biomass because the pulse of P unmasked the inhibitory effect of UVR. This unmasking effect might be related to greater photodamage caused by an excess of electron flux after a P pulse (higher ETRmax without an efficient release of carbon as the mechanism to dissipate the reducing power of photosynthetic electron transport.

  9. Dust in an acidified ocean: iron bioavailability, phytoplankton growth and DMS

    Science.gov (United States)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M. G.; Tremblay, J. E.; Tortell, P. D.; Yang, G.; Shi, G. Y.; Gao, H.; Semeniuk, D.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Pena, A.; Richardson, W.

    2015-12-01

    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 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 maintained 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%) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15% reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. 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.

  10. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Iris Kriest; Geoffrey T Evans

    2000-12-01

    This work presents models of the vertical distribution and flux of phytoplankton aggregates, including changes with time in the distribution of aggregate sizes and sinking speeds. The distribution of sizes is described by two parameters, the mass and number of aggregates, which greatly reduces the computational cost of the models. Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations is small, and it presents the difference in timing between settlement of aggregates and fecal pellets.

  11. Controlling defectiveness in a complex product

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C.L.

    1976-09-01

    A common practice when measuring defectiveness in a complicated product is to assign ''demerit'' points to each defect in proportion to the seriousness of the fault. A plan is presented for monitoring defectives by using a modified demerit per unit control chart. The statistics presented are basic to control charts for demerits. What is different is the chart format which has the advantage of minimum effort for daily updates and independence from required sample sizes. Basically, the charts were designed for simplicity of use where product quantities are not large. Emphasis is placed on maintaining perspective between plotting data and completing the circle of defect reporting, analysis and corrective action feedback.

  12. Physicochemical conditions in affecting the distribution of spring phytoplankton community

    Science.gov (United States)

    Wei, Yuqiu; Liu, Haijiao; Zhang, Xiaodong; Xue, Bing; Munir, Sonia; Sun, Jun

    2017-03-01

    To better understand the physicochemical conditions in affecting regional distribution of phytoplankton community, one research cruise was carried out in the Bohai Sea and Yellow Sea during 3rd and 23th May, 2010. The phytoplankton community, including Bacillariophyta (105 taxa), Pyrrophyta (54 taxa), Chrysophyta (1 taxon) and Chlorophyta (2 taxa), had been identified and clearly described from six ecological provinces. And, the six ecological provinces were partitioned based on the top twenty dominant species related with notable physicochemical parameters. In general, the regional distributions of phytoplankton ecological provinces were predominantly influenced by the physicochemical properties induced by the variable water masses and circulations. The predominant diatoms in most of water samples showed well adaptability in turbulent and eutrophic conditions. However, several species of dinoflagellates e.g., Protoperidinium conicum, Protoperidinium triestinum, Protoperidinium sp. and Gymnodinium lohmanni preferred warmer, saltier and nutrient-poor environment. Moreover, the dinoflagellates with high frequency in the Yellow Sea might be transported from the Yellow Sea Warm Current. The horizontal distribution of phytoplankton was depicted by diatoms and controlled by phosphate concentration, while the vertical distribution was mainly supported by light and nutrients availability in the subsurface and bottom layers, respectively.

  13. The Molecular Ecophysiology of Programmed Cell Death in Marine Phytoplankton

    Science.gov (United States)

    Bidle, Kay D.

    2015-01-01

    Planktonic, prokaryotic, and eukaryotic photoautotrophs (phytoplankton) share a diverse and ancient evolutionary history, during which time they have played key roles in regulating marine food webs, biogeochemical cycles, and Earth's climate. Because phytoplankton represent the basis of marine ecosystems, the manner in which they die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining upper-ocean biogeochemistry. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of nutrient stressors and are employed by parasitic viruses, play an integral role in determining the cell fate of diverse photoautotrophs in the modern ocean. Indeed, these multifaceted death pathways continue to shape the success and evolutionary trajectory of diverse phytoplankton lineages at sea. Research over the past two decades has employed physiological, biochemical, and genetic techniques to provide a novel, comprehensive, mechanistic understanding of the factors controlling this key process. Here, I discuss the current understanding of the genetics, activation, and regulation of PCD pathways in marine model systems; how PCD evolved in unicellular photoautotrophs; how it mechanistically interfaces with viral infection pathways; how stress signals are sensed and transduced into cellular responses; and how novel molecular and biochemical tools are revealing the impact of PCD genes on the fate of natural phytoplankton assemblages.

  14. Operation and Control of Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Huusom, Jakob Kjøbsted; Nordblad, Mathias

    -product. Current literature indicates that enzymatic processing of oils and fats to produce biodiesel is technically feasible and developments in immobilization technology indicate that enzyme catalysts can become cost effective compared to chemical processing. However, with very few exceptions, enzyme technology...... is not currently used in commercial-scale biodiesel production. This is mainly due to non-optimized process designs, which do not use the full potential of the catalysts in a cost-efficient way. Furthermore is it unclear what process variables need to be monitored and controlled to ensure optimal economics...... an enzymatic route, batch operation is a straightforward and efficient means for producing BD with its main disadvantage being the downtime between batches. For large-scale production of biodiesel, continuous operation is an attractive alternative as it enables efficient use of manpower and capital assets...

  15. Decision Support for effective production control

    DEFF Research Database (Denmark)

    Africa, E.; Nehzati, T.; Strandhagen, J.O.

    2012-01-01

    This study aims to identify the actual needs of decision makers for decision support in the production control activity, considering the role and cognitive skills of human decision-makers in the decision-making process. Multiple case studies have been conducted in order to gain practical insights...... from the manufacturing industry. This paper contributes to raise the issues that should be considered for successful implementation of the decision support systems in practice....

  16. Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Madhu, N.V.; Jyothibabu, R.; Balachandran, K.K.

    . R, Balachandran. K. K National Institute of Oceanography, Regional Centre, Kochi -18, India Abstract Changes in the autotrophic pico- (0.2-2µm), nano- (2-20µm) and micro- (>20µm) plankton biomass (chlorophyll a) and primary production were... in the pico- (0.2 - 2µm), nano- (2 - 20µm) and micro- (>20µm) fractions showed significant variations in the estuarine and coastal waters (Fig. 4). The total chl a was higher in the estuary, both in the surface (av. 13.7 ± 8 mgm -3 ) and bottom (av. 9.6 ± 4...

  17. 21 CFR 226.40 - Production and control procedures.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Production and control procedures. 226.40 Section...) DRUGS: GENERAL CURRENT GOOD MANUFACTURING PRACTICE FOR TYPE A MEDICATED ARTICLES Product Quality Control § 226.40 Production and control procedures. Production and control procedures shall include...

  18. 21 CFR 820.70 - Production and process controls.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Production and process controls. 820.70 Section...) MEDICAL DEVICES QUALITY SYSTEM REGULATION Production and Process Controls § 820.70 Production and process controls. (a) General. Each manufacturer shall develop, conduct, control, and monitor production...

  19. 21 CFR 211.188 - Batch production and control records.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Batch production and control records. 211.188... Reports § 211.188 Batch production and control records. Batch production and control records shall be... production and control of each batch. These records shall include: (a) An accurate reproduction of...

  20. Changes in phytoplankton communities along nutrient gradients in Lake Taihu: evidence for nutrient reduction strategies

    Science.gov (United States)

    Ai, Ying; Bi, Yonghong; Hu, Zhengyu

    2015-03-01

    An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu, East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area, where algal blooms often appear, and co-dominated in the southern area. In the northern part, the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume, both along the phosphorus (P) gradient, and between total nitrogen levels (≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no significant variations in total biovolume along P and N (nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced P release needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms.

  1. Production planning and control of less emitting production systems

    Energy Technology Data Exchange (ETDEWEB)

    Haasis, H.D. [Bremen Univ. (Germany)

    1995-12-31

    The concept of integral environmental protection has been growing in importance within Western Europe in recent years. Increasingly, it has come to be recognized that no one part of the environment is separate from any other, it functions as a whole. Yet, pollution control was until recently, usually based on an approach which considers emissions to air, water, and land separately. That has begun to change, particularly since the 1987 report by the World Commission on Environment and Development. This can be recognized, for example, within the proposal for a Directive of the Council of the European Union on Integrated Pollution Prevention and Control. By this, the environmental media are placed on an equal legislative footing so that the final result will be that the way in which an installation is operated will be better for the whole environment. In other words, less emission production systems are obtained. Realization of an integral concept or of less emission production systems initially requires technical measures for the avoidance and the minimization of emissions, as well as recovery and recycling of materials and substances

  2. An assessment of phytoplankton primary productivity in the Arctic Ocean from satellite ocean color/in situ chlorophyll‐a based models

    Science.gov (United States)

    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

  3. An assessment of phytoplankton primary productivity in the Arctic Ocean from satellite ocean color/in situ chlorophyll-a based models.

    Science.gov (United States)

    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.

  4. To what extent does the salinity flux influence phytoplankton blooms? - Baltic Sea modeling study

    Science.gov (United States)

    Cieszyńska, Agata; Stramska, Małgorzata

    2016-04-01

    This work is focused on numerical modeling of biological-physical interactions and their influence on phytoplankton production and vertical distribution of biomass and its variability in the surface waters of the Baltic Sea. The area of interest is an inland sea with water salinity much smaller than observed in the global ocean (about one fifth of the open ocean value). Vertical distribution of the salinity has a significant influence on water column density stratification, and therefore influences intensity of mixing and the depth of mixed layer. This, in turn, defines environmental conditions for phytoplankton growth. Vertical distribution of water salinity in the basin is controlled by processes such as evaporation/precipitation, freezing/melting of sea ice and runoff of freshwater from land. There are a lot of different phytoplankton species in the area of the Baltic Sea. Every single one has its own characteristics and is sensitive to distinct complex environmental conditions. Biological-physical interactions controlling these microorganisms' life cycles are multiplicitous and because of their complexity difficult to quantify. The best and probably only way to study presented issue is the usage of numerical modeling tool. The results presented here are based on 1D numerical simulations carried out with Princeton Ocean Model (POM, http://www.ccpo.odu.edu/POMWEB/) merged with the Ecological Regional Ecosystem Model (ERGOM, http://ergom.net/) developed for the Baltic Sea research by German scientists from the Leibniz Institute for Baltic Sea Research in Warnemünde. In model simulations surface salinity flux was determined from the difference between the precipitation and evaporation rate at the air-sea interface. Data for parameterization of atmospheric forcing were defined based on data sets from National Centers of Environmental Prediction (NCEP). We carried out systematic calculations using different values of surface fluxes encompassing the range of

  5. Phytoplankton-bacteria coupling under elevated CO2 levels: a stable isotope labelling study

    Directory of Open Access Journals (Sweden)

    J. J. Middelburg

    2010-11-01

    Full Text Available The potential impact of rising carbon dioxide (CO2 on carbon transfer from phytoplankton to bacteria was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Sets of mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated under 1× (~350 μatm, 2× (~700 μatm, and 3× present day CO2 (~1050 μatm initial seawater and sustained atmospheric CO2 levels for 3 weeks. 13C labelled bicarbonate was added to all mesocosms to follow the transfer of carbon from dissolved inorganic carbon (DIC into phytoplankton and subsequently heterotrophic bacteria, and settling particles. Isotope ratios of polar-lipid-derived fatty acids (PLFA were used to infer the biomass and production of phytoplankton and bacteria. Phytoplankton PLFA were enriched within one day after label addition, whilst it took another 3 days before bacteria showed substantial enrichment. Group-specific primary production measurements revealed that coccolithophores showed higher primary production than green algae and diatoms. Elevated CO2 had a significant positive effect on post-bloom biomass of green algae, diatoms, and bacteria. A simple model based on measured isotope ratios of phytoplankton and bacteria revealed that CO2 had no significant effect on the carbon transfer efficiency from phytoplankton to bacteria during the bloom. There was no indication of CO2 effects on enhanced settling based on isotope mixing models during the phytoplankton bloom, but this could not be determined in the post-bloom phase. Our results suggest that CO2 effects are most pronounced in the post-bloom phase, under nutrient limitation.

  6. The role of phytoplankton photosynthesis in global biogeochemical cycles.

    Science.gov (United States)

    Falkowski, P G

    1994-03-01

    Phytoplankton biomass in the world's oceans amounts to only ∽1-2% of the total global plant carbon, yet these organisms fix between 30 and 50 billion metric tons of carbon annually, which is about 40% of the total. On geological time scales there is profound evidence of the importance of phytoplankton photosynthesis in biogeochemical cycles. It is generally assumed that present phytoplankton productivity is in a quasi steady-state (on the time scale of decades). However, in a global context, the stability of oceanic photosynthetic processes is dependent on the physical circulation of the upper ocean and is therefore strongly influenced by the atmosphere. The net flux of atmospheric radiation is critical to determining the depth of the upper mixed layer and the vertical fluxes of nutrients. These latter two parameters are keys to determining the intensity, and spatial and temporal distributions of phytoplankton blooms. Atmospheric radiation budgets are not in steady-state. Driven largely by anthropogenic activities in the 20th century, increased levels of IR- absorbing gases such as CO2, CH4 and CFC's and NOx will potentially increase atmospheric temperatures on a global scale. The atmospheric radiation budget can affect phytoplankton photosynthesis directly and indirectly. Increased temperature differences between the continents and oceans have been implicated in higher wind stresses at the ocean margins. Increased wind speeds can lead to higher nutrient fluxes. Throughout most of the central oceans, nitrate concentrations are sub-micromolar and there is strong evidence that the quantum efficiency of Photosystem II is impaired by nutrient stress. Higher nutrient fluxes would lead to both an increase in phytoplankton biomass and higher biomass-specific rates of carbon fixation. However, in the center of the ocean gyres, increased radiative heating could reduce the vertical flux of nutrients to the euphotic zone, and hence lead to a reduction in phytoplankton

  7. Relationship between bacteria and phytoplankton during the giant jellyfish Nemopilema nomurai bloom in an oligotrophic temperate marine ecosystem

    Institute of Scientific and Technical Information of China (English)

    ZENG Yang; HUANG Xuguang; HUANG Bangqin; MI Tiezhu

    2016-01-01

    Bacterial abundance, phytoplankton community structure and environmental parameters were investigated to study the relationships between bacteria and phytoplankton during giant jellyfish Nemopilema nomurai blooms in the central Yellow Sea during 2013. N. nomurai appeared in June, increased in August, reached a peak and began to degrade in September 2013. Results showed that phosphate was possible a key nutrient for both phytoplankton and bacteria in June, but it changed to nitrate in August and September. Phytoplankton composition significantly changed that pico-phytoplankton relative biomass significantly increased, whereas other size phytoplankton significantly decreased during jellyfish bloom. In June, a significantly positive correlation was observed between chlorophyll a concentration and bacterial abundance (r=0.67, P0.05, n=25), but the relationship (r=0.71, P<0.001, n=31) was rebuilt with jellyfish degradation in September. In August, small size phytoplankton occupied the mixed layer in offshore stations, while bacteria almost distributed evenly in vertical. Chlorophyll a concentration significantly increased from (0.42±0.056) μg/L in June to (0.74±0.174) μg/L in August , while bacterial abundance just slightly increased. Additionally, the negative net community production indicated that community respiration was not entirely determined by the local primary productivity in August. These results indicated that jellyfish blooms potentially affect coupling of phytoplankton and bacteria in marine ecosystems.

  8. QUALITY CONTROL OF SOME TRADITIONAL MEAT PRODUCTS

    Directory of Open Access Journals (Sweden)

    S. DOBRINAS

    2014-03-01

    Full Text Available In this paper, we present the characterization of six traditional meat products: smoked file, smoked bacon, pork sausages, sausage prepared from swine’s entrails, pork pastrami, sheep sausages. Organoleptic tests (the aspect and shape, the aspect of freshly cut in the section, smell, taste and consistency, physico-chemical and microbiological determinations (NTG, Salmonella, Listeria monocytogenes and Escherichia coli were performed. These analyzes are a part of quality control that must be done in order to obtain a certificate from the Ministry of Agriculture for a traditional product. After identification of H2S and starch and according to fat oxidation degree it was concluded that analyzed samples didn’t contain counterfeiters and all parameters analyzed are within the maximum limits allowed by law. Considering all the procedures for manufacturing, characteristics of raw and auxiliary materials, organoleptic properties of final products analyzed in this study, it can be concluded that analyzed meat specialties meet the requirements of Ministry Order no. 690/28.09.2004 for the traditional products certification.

  9. Diel Cycle of Photosynthetic Electron Transport and Fluorescence Characteristics in Natural Phytoplankton Communities.

    Science.gov (United States)

    Kolber, Z.; Klimov, D.

    2007-12-01

    Phytoplankton photosynthetic performance is strongly controlled by the daily irradiance cycle. The most pronounced effects are the photoinhibition of photosynthetic activity in the morning and noon hours, and the development of non-photochemical quenching throughout the day. These two effects are extensively investigated as they significantly diminish the daily production rates. Less obvious, but equally important are the daily changes in the kinetics of rate-limiting electron transport within Photosystem II and Photosystem I of the photosynthetic apparatus. Using a fast repetition rate (FRR) fluorometer operating in the continuous flow-through mode in the Eastern Tropical Pacific, we observed theses rates to decelerate by a factor of five during the night, but recovering to a full speed just before the dawn. We characterized the effects of these changes on the photosynthetic performance of phytoplankton by continuously recording the fast light curves (variable fluorescence versus irradiance relationship). Besides controlling photochemistry, these changes strongly affect the chlorophyll fluorescence yield, especially when measured with a multiple turnover excitation. We will discuss how the knowledge of these rate-limiting steps may improve the fluorescence-based estimates of photosynthesis and chlorophyll biomass.

  10. Biological Carbon Dioxide Assimilation Process Using Marine Phytoplankton Tetraselmis suecica and Bivalve Perna viridis

    OpenAIRE

    Sirichai Dharmvanij; Sorawit Powtongsook; Chompunut Chairattana; Piamsak Manesveta

    2012-01-01

    The Biological CO2 assimilation process using marine phytoplankton and marine bivalve was evaluated by carbon assimilation of the green mussel Perna viridis fed with Tetraselmis suecica under laboratory condition. Incorporation of carbon dioxide into phytoplankton biomass was performed through aeration. The experiment consisted of three treatments i.e. mussels without feeding (Control), mussels fed with T. suecica cultured with air (Treatment 1: T-Air), and mussels fed with T. suecica culture...

  11. Phytoplankton and nutrient distributions in a front-eddy area adjacent to the coastal upwelling zone off Concepcion (Chile): implications for ecosystem productivity.

    Science.gov (United States)

    Morales, Carmen; Anabalón, Valeria; Hormazábal, Samuel; Cornejo, Marcela; Bento, Joaquim; Silva, Nelson

    2016-04-01

    The impact that sub-mesoscale (1-10 km) to mesocale (50-100 km) oceanographic variability has on plankton and nutrient distributions (horizontal and vertical) in the coastal upwelling and transition zones off Concepcion was the focus of this study. Satellite time-series data (wind, sea-surface temperature (SST), and altimetry) were used to understand the dynamic context of in situ data derived from a short-term front survey (3 d) during the upwelling period (3-6 February, 2014). The survey included two transects perpendicular to the coast, covering the shelf and shelf-break areas just north of Punta Lavapie, a main upwelling center (˜37° S). Wind and SST time-series data indicated that the survey was undertaken just after a moderate upwelling event (end of January) which lead to a relaxation phase during early February. A submesoscale thermal front was detected previous to and during the survey and results from an eddy tracking algorithm based on altimetry data indicated that this front (F1) was flanked on its oceanic side by an anticyclonic, mesoscale eddy (M1), which was ˜25 d old at the sampling time. M1 strengthened the thermal gradient of F1 by bringing warmer oceanic water nearer to the colder coastal upwelling zone. The distributions of hydrographic variables and nutrients in the water column (interaction creates a complex field of submesoscale processes in the top layer, including vertical nutrient injections and lateral stirring, which contributes to the exportation of coastal communities to the open ocean in this region. We discuss how this interaction might affect ecosystem productivity in the coastal band.

  12. Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

    DEFF Research Database (Denmark)

    Daniels, C.J.; Poulton, A. J.; Esposito, M.;

    2015-01-01

    The spring bloom is a key annual event in the phenology of pelagic ecosystems, making a major contribution to the oceanic biological carbon pump through the production and export of organic carbon. However, there is little consensus as to the main drivers of spring bloom formation, exacerbated...... by a lack of in situ observations of the phytoplankton community composition and its evolution during this critical period. We investigated the dynamics of the phytoplankton community structure at two contrasting sites in the Iceland and Norwegian Basins during the early stage (25 March–25 April...... a biomass. The ICB phytoplankton composition appeared primarily driven by the physicochemical environment, with periodic events of increased mixing restricting further increases in biomass. In contrast, the NWB phytoplankton community was potentially limited by physicochemical and/or biological factors...

  13. Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions

    Science.gov (United States)

    Hornick, Thomas; Bach, Lennart T.; Crawfurd, Katharine J.; Spilling, Kristian; Achterberg, Eric P.; Woodhouse, Jason N.; Schulz, Kai G.; Brussaard, Corina P. D.; Riebesell, Ulf; Grossart, Hans-Peter

    2017-01-01

    The oceans absorb about a quarter of the annually produced anthropogenic atmospheric carbon dioxide (CO2), resulting in a decrease in surface water pH, a process termed ocean acidification (OA). Surprisingly little is known about how OA affects the physiology of heterotrophic bacteria or the coupling of heterotrophic bacteria to phytoplankton when nutrients are limited. Previous experiments were, for the most part, undertaken during productive phases or following nutrient additions designed to stimulate algal blooms. Therefore, we performed an in situ large-volume mesocosm ( ˜ 55 m3) experiment in the Baltic Sea by simulating different fugacities of CO2 (fCO2) extending from present to future conditions. The study was conducted in July-August after the nominal spring bloom, in order to maintain low-nutrient conditions throughout the experiment. This resulted in phytoplankton communities dominated by small-sized functional groups (picophytoplankton). There was no consistent fCO2-induced effect on bacterial protein production (BPP), cell-specific BPP (csBPP) or biovolumes (BVs) of either free-living (FL) or particle-associated (PA) heterotrophic bacteria, when considered as individual components (univariate analyses). Permutational Multivariate Analysis of Variance (PERMANOVA) revealed a significant effect of the fCO2 treatment on entire assemblages of dissolved and particulate nutrients, metabolic parameters and the bacteria-phytoplankton community. However, distance-based linear modelling only identified fCO2 as a factor explaining the variability observed amongst the microbial community composition, but not for explaining variability within the metabolic parameters. This suggests that fCO2 impacts on microbial metabolic parameters occurred indirectly through varying physicochemical parameters and microbial species composition. Cluster analyses examining the co-occurrence of different functional groups of bacteria and phytoplankton further revealed a separation of

  14. Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica

    Science.gov (United States)

    Ryan-Keogh, Thomas J.; DeLizo, Liza M.; Smith, Walker O.; Sedwick, Peter N.; McGillicuddy, Dennis J.; Moore, C. Mark; Bibby, Thomas S.

    2017-02-01

    The bioavailability of iron influences the distribution, biomass and productivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (> 24 h) and short-term (24 h) iron-addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December-February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (σPSII) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplankton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea.

  15. Effect of ocean acidification and elevated fCO2 on trace gas production by a Baltic Sea summer phytoplankton community

    Science.gov (United States)

    Webb, Alison L.; Leedham-Elvidge, Emma; Hughes, Claire; Hopkins, Frances E.; Malin, Gill; Bach, Lennart T.; Schulz, Kai; Crawfurd, Kate; Brussaard, Corina P. D.; Stuhr, Annegret; Riebesell, Ulf; Liss, Peter S.

    2016-08-01

    The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on trace gas biogeochemistry, a large-scale mesocosm experiment was performed off Tvärminne Research Station, Finland, in summer 2012. During the second half of the experiment, dimethylsulfide (DMS) concentrations in the highest-fCO2 mesocosms (1075-1333 µatm) were 34 % lower than at ambient CO2 (350 µatm). However, the net production (as measured by concentration change) of seven halocarbons analysed was not significantly affected by even the highest CO2 levels after 5 weeks' exposure. Methyl iodide (CH3I) and diiodomethane (CH2I2) showed 15 and 57 % increases in mean mesocosm concentration (3.8 ± 0.6 increasing to 4.3 ± 0.4 pmol L-1 and 87.4 ± 14.9 increasing to 134.4 ± 24.1 pmol L-1 respectively) during Phase II of the experiment, which were unrelated to CO2 and corresponded to 30 % lower Chl a concentrations compared to Phase I. No other iodocarbons increased or showed a peak, with mean chloroiodomethane (CH2ClI) concentrations measured at 5.3 (±0.9) pmol L-1 and iodoethane (C2H5I) at 0.5 (±0.1) pmol L-1. Of the concentrations of bromoform (CHBr3; mean 88.1 ± 13.2 pmol L-1), dibromomethane (CH2Br2; mean 5.3 ± 0.8 pmol L-1), and dibromochloromethane (CHBr2Cl, mean 3.0 ± 0.5 pmol L-1), only CH2Br2 showed a decrease of 17 % between Phases I and II, with CHBr3 and CHBr2Cl showing similar mean concentrations in both phases. Outside the mesocosms, an upwelling event was responsible for bringing colder, high-CO2, low-pH water to the surface starting on day t16 of the experiment; this variable CO2 system with frequent upwelling events implies that the community of the Baltic Sea is acclimated to regular significant declines in pH caused by up to 800 µatm fCO2. After

  16. 21 CFR 211.186 - Master production and control records.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Master production and control records. 211.186... Reports § 211.186 Master production and control records. (a) To assure uniformity from batch to batch, master production and control records for each drug product, including each batch size thereof, shall...

  17. Observing phytoplankton physiology and ocean ecosystem structure from space

    Science.gov (United States)

    Schultz, Patrick

    Changes in ocean circulation in response to anthropogenic climate change affect ocean biology on a global scale. Based on a previously published empirical model that links ocean circulation to chlorophyll and chlorophyll to primary production, I predict an increase in primary production of 10--27% at the end of the 23rd century under four times pre-industrial atmospheric CO 2. The uncertainty in this prediction largely stems from the reliance on chlorophyll as the only model constraint. Chlorophyll concentrations are difficult to interpret, as they depend on phytoplankton biomass and cellular pigmentation, which adjusts to growth conditions. The objective of this thesis is to bridge the gap between laboratory-based knowledge of physiological adjustments to growth conditions and global satellite observations to reduce ambiguities in the interpretation of chlorophyll concentrations on a global scale. Satellite estimates of phytoplankton carbon and the chlorophyll to carbon ratio (Chl:C), a measure of pigmentation, are the foundation of this work. My main contribution is a re-evaluation of chlorophyll variability in the eastern subarctic Pacific, which updates the old paradigm for seasonal phytoplankton dynamics in this iron-limited region. In contrast to previous studies, I conclude that the consistently low chlorophyll concentrations are caused by a suppression of Chl:C by iron stress, rather than by reduced accumulation of phytoplankton biomass. Field observations during iron enrichment experiments and model simulations confirm that the satellite-observed suppression of Chl:C is consistent with physiological adjustments to low iron. On a global scale, I analyze how phytoplankton biomass and pigmentation interact to yield the spatial structure in surface chlorophyll and I employ a mechanistic photoacclimation model to diagnose the contributions of light, nutrients and temperature to the spatial structure in Chl:C. I further argue that the temporal variability of

  18. Oil Reservoir Production Optimization using Optimal Control

    DEFF Research Database (Denmark)

    Völcker, Carsten; Jørgensen, John Bagterp; Stenby, Erling Halfdan

    2011-01-01

    Practical oil reservoir management involves solution of large-scale constrained optimal control problems. In this paper we present a numerical method for solution of large-scale constrained optimal control problems. The method is a single-shooting method that computes the gradients using the adjo......Practical oil reservoir management involves solution of large-scale constrained optimal control problems. In this paper we present a numerical method for solution of large-scale constrained optimal control problems. The method is a single-shooting method that computes the gradients using...... the adjoint method. We use an Explicit Singly Diagonally Implicit Runge-Kutta (ESDIRK) method for the integration and a quasi-Newton Sequential Quadratic Programming (SQP) algorithm for the constrained optimization. We use this algorithm in a numerical case study to optimize the production of oil from an oil...... reservoir using water ooding and smart well technology. Compared to the uncontrolled case, the optimal operation increases the Net Present Value of the oil field by 10%....

  19. A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

    Directory of Open Access Journals (Sweden)

    K. Fennel

    2011-01-01

    Full Text Available The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer. The mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. We present results from a realistic, 3-dimensional, physical-biological model that includes the processes thought to be of first order importance to hypoxia formation and demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input. We find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes. We hypothesize that increased retention of river water in high discharge years explains this phenomenon.

  20. Macroecological patterns in the distribution of marine phytoplankton

    DEFF Research Database (Denmark)

    Mousing, Erik Askov

    Marine phytoplankton are responsible for approximately half of the global total primary production. The photosynthesis they carry out sustains higher trophic levels in the marine ecosystem. Changes in phytoplankton community composition can have cascading effects on food web dynamics, total...... stratification limiting the flux of nutrients from the deep ocean). This affect has important implications for the global carbon cycle and should be included in future climate models. In manuscript II, changes in the mean cyst size of dinoflagellates are investigated in relation to temperature changes during...... in the 1970s. However, increasing silicate in the deep ocean over the same period has indicated that there is an overlooked source of silicate and has brought the paradigm of silica limitation into question. Here, it is shown that silicate-using protists became more diluted in the sediment after 1970...

  1. Macroecological patterns in the distribution of marine phytoplankton

    DEFF Research Database (Denmark)

    Mousing, Erik Askov

    Marine phytoplankton are responsible for approximately half of the global total primary production. The photosynthesis they carry out sustains higher trophic levels in the marine ecosystem. Changes in phytoplankton community composition can have cascading effects on food web dynamics, total...... stratification limiting the flux of nutrients from the deep ocean). This affect has important implications for the global carbon cycle and should be included in future climate models. In manuscript II, changes in the mean cyst size of dinoflagellates are investigated in relation to temperature changes during...... in the 1970s. However, increasing silicate in the deep ocean over the same period has indicated that there is an overlooked source of silicate and has brought the paradigm of silica limitation into question. Here, it is shown that silicate-using protists became more diluted in the sediment after 1970...

  2. Microbial control of hydrogen sulfide production

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J. [Univ. of Oklahoma, Tulsa, OK (United States)] [and others

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  3. Sensitivity in forward modeled hyperspectral reflectance due to phytoplankton groups

    Science.gov (United States)

    Manzo, Ciro; Bassani, Cristiana; Pinardi, Monica; Giardino, Claudia; Bresciani, Mariano

    2016-04-01

    Phytoplankton is an integral part of the ecosystem, affecting trophic dynamics, nutrient cycling, habitat condition, and fisheries resources. The types of phytoplankton and their concentrations are used to describe the status of water and the processes inside of this. This study investigates bio-optical modeling of phytoplankton functional types (PFT) in terms of pigment composition demonstrating the capability of remote sensing to recognize freshwater phytoplankton. In particular, a sensitivity analysis of simulated hyperspectral water reflectance (with band setting of HICO, APEX, EnMAP, PRISMA and Sentinel-3) of productive eutrophic waters of Mantua lakes (Italy) environment is presented. The bio-optical model adopted for simulating the hyperspectral water reflectance takes into account the reflectance dependency on geometric conditions of light field, on inherent optical properties (backscattering and absorption coefficients) and on concentrations of water quality parameters (WQPs). The model works in the 400-750nm wavelength range, while the model parametrization is based on a comprehensive dataset of WQP concentrations and specific inherent optical properties of the study area, collected in field surveys carried out from May to September of 2011 and 2014. The following phytoplankton groups, with their specific absorption coefficients, a*Φi(λ), were used during the simulation: Chlorophyta, Cyanobacteria with phycocyanin, Cyanobacteria and Cryptophytes with phycoerythrin, Diatoms with carotenoids and mixed phytoplankton. The phytoplankton absorption coefficient aΦ(λ) is modelled by multiplying the weighted sum of the PFTs, Σpia*Φi(λ), with the chlorophyll-a concentration (Chl-a). To highlight the variability of water reflectance due to variation of phytoplankton pigments, the sensitivity analysis was performed by keeping constant the WQPs (i.e., Chl-a=80mg/l, total suspended matter=12.58g/l and yellow substances=0.27m-1). The sensitivity analysis was

  4. Assessing Pigment-Based Phytoplankton Community Distributions in the Red Sea

    KAUST Repository

    Kheireddine, Malika

    2017-05-10

    Pigment-based phytoplankton community composition and primary production were investigated for the first time in the Red Sea in February-April 2015 to demonstrate how the strong south to north environmental gradients determine phytoplankton community structure in Red Sea offshore regions (along the central axis). Taxonomic pigments were used as size group markers of pico, nano-, and microphytoplankton. Phytoplankton primary production rates associated with the three phytoplankton groups (pico-, nano-, and microphytoplankton) were estimated using a bio-optical model. Pico- (Synechococcus and Prochlorococcus sp.) and Nanophytoplankton (Prymnesiophytes and Pelagophytes) were the dominant size groups and contributed to 49 and 38%, respectively, of the phytoplankton biomass. Microphytoplankton (diatoms) contributed to 13% of the phytoplankton biomass within the productive layer (1.5 Zeu). Sub-basin and mesoscale structures (cyclonic eddy and mixing) were exceptions to this general trend. In the southern Red Sea, diatoms and picophytoplankton contributed to 27 and 31% of the phytoplankton biomass, respectively. This result induced higher primary production rates (430 ± 50 mgC m−2 d−1) in this region (opposed to CRS and NRS). The cyclonic eddy contained the highest microphytoplankton proportion (45% of TChla) and the lowest picophytoplankton contribution (17% of TChla) while adjacent areas were dominated by pico- and nano-phytoplankton. We estimated that the cyclonic eddy is an area of enhanced primary production, which is up to twice those of the central part of the basin. During the mixing of the water column in the extreme north of the basin, we observed the highest TChla integrated (40 mg m−2) and total primary production rate (640 mgC m−2 d−1) associated with the highest nanophytoplankton contribution (57% of TChla). Microphytoplankton were a major contributor to total primary production (54%) in the cyclonic eddy. The contribution of picophytoplankton

  5. Wind farms production: Control and prediction

    Science.gov (United States)

    El-Fouly, Tarek Hussein Mostafa

    Wind energy resources, unlike dispatchable central station generation, produce power dependable on external irregular source and that is the incident wind speed which does not always blow when electricity is needed. This results in the variability, unpredictability, and uncertainty of wind resources. Therefore, the integration of wind facilities to utility electrical grid presents a major challenge to power system operator. Such integration has significant impact on the optimum power flow, transmission congestion, power quality issues, system stability, load dispatch, and economic analysis. Due to the irregular nature of wind power production, accurate prediction represents the major challenge to power system operators. Therefore, in this thesis two novel models are proposed for wind speed and wind power prediction. One proposed model is dedicated to short-term prediction (one-hour ahead) and the other involves medium term prediction (one-day ahead). The accuracy of the proposed models is revealed by comparing their results with the corresponding values of a reference prediction model referred to as the persistent model. Utility grid operation is not only impacted by the uncertainty of the future production of wind farms, but also by the variability of their current production and how the active and reactive power exchange with the grid is controlled. To address this particular task, a control technique for wind turbines, driven by doubly-fed induction generators (DFIGs), is developed to regulate the terminal voltage by equally sharing the generated/absorbed reactive power between the rotor-side and the gridside converters. To highlight the impact of the new developed technique in reducing the power loss in the generator set, an economic analysis is carried out. Moreover, a new aggregated model for wind farms is proposed that accounts for the irregularity of the incident wind distribution throughout the farm layout. Specifically, this model includes the wake effect

  6. The influence of dissolved organic carbon on bacterial phosphorus uptake and bacteria-phytoplankton dynamics in two Minnesota lakes

    Science.gov (United States)

    Stets, E.G.; Cotner, J.B.

    2008-01-01

    The balance of production in any ecosystem is dependent on the flow of limiting nutrients into either the autotrophic or heterotrophic components of the food web. To understand one of the important controls on the flow of inorganic nutrients between phytoplankton and bacterioplankton in lakes, we manipulated dissolved organic carbon (DOC) in two lakes of different trophic status. We hypothesized that labile DOC additions would increase bacterial phosphorus (P) uptake and decrease the response of phytoplankton to nutrient additions. Supplemental nutrients and carbon (C), nitrogen (N, 1.6 ??mol NH4Cl L-1 d-1), P (0.1 ??mol KH 2PO4 L-1 d-1), and DOC (glucose, 15 ??mol C L-1 d-1) were added twice daily to 8-liter experimental units. We tested the effect of added DOC on chlorophyll concentration, bacterial production, biomass, and P uptake using size-fractionated 33P-PO4 uptake. In the oligotrophic lake, DOC additions stimulated bacterial production and increased bacterial biomass-specific P uptake. Bacteria consumed added DOC, and chlorophyll concentrations were significantly lower in carboys receiving DOC additions. In the eutrophic lake, DOC additions had less of a stimulatory effect on bacterial production and biomass-specific P uptake. DOC accumulated over the time period, and there was little evidence for a DOC-induced decrease in phytoplankton biomass. Bacterial growth approached the calculated ??max and yet did not accumulate biomass, indicating significant biomass losses, which may have constrained bacterial DOC consumption. Excess bacterial DOC consumption in oligotrophic lakes may result in greater bacterial P affinity and enhanced nutrient uptake by the heterotrophic compartment of the food web. On the other hand, constraints on bacterial biomass accumulation in eutrophic lakes, from either viral lysis or bacterial grazing, can allow labile DOC to accumulate, thereby negating the effect of excess DOC on the planktonic food web. ?? 2008, by the American

  7. Quantifying the impact of submesoscale processes on the spring phytoplankton bloom in a turbulent upper ocean using a Lagrangian approach

    Science.gov (United States)

    Brody, Sarah R.; Lozier, M. Susan; Mahadevan, Amala

    2016-05-01

    The spring phytoplankton bloom in the subpolar North Atlantic and the mechanisms controlling its evolution and onset have important consequences for marine ecosystems and carbon cycling. Submesoscale mixed layer eddies (MLEs) play a role in the onset of the bloom by creating localized stratification and alleviating phytoplankton light limitation; however, the importance of MLEs for phytoplankton in a turbulent surface mixed layer has not yet been examined. We explore the effect of MLEs on phytoplankton by simulating their trajectories with Lagrangian particles subject to turbulent vertical displacements in an MLE-resolving model. By tracking the light exposure of the simulated phytoplankton, we find that MLEs can advance the timing of the spring bloom by 1 to 2 weeks, depending on surface forcing conditions. The onset of the bloom is linked with the onset of positive heat fluxes, whether or not MLEs are present.

  8. Evolution of nutrient structure and phytoplankton composition in the Jiaozhou Bay ecosystem

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shu-jiang; JIAO Nian-zhi; WU Chang-wen; LIANG Bing; ZHANG Shu-yi

    2005-01-01

    The inventories of nutrients in the surface water and large phytoplankton( > 69 μm) were analyzed from the data set of JERS ecological database about a typical coastal waters, the Jiaozhou Bay, China, from 1960s for N, P and from 1980s for Si. By examining long-term changes of nutrient concentration, calculating stoichiometric balance, and comparing diatom composition, Si limitation of diatom production was found to be more possible. The possibility of Si limitation was from 37% in 1980s to 50% in 1990s. Jiaozhou Bay ecosystem is becoming serious eutrophication, with notable increase of NO2-N, NO3-N and NH4-N from 0.1417 μmol/L, 0.5414 μmol/L,1.7222 μmol/L in 1960s to 0.9551 μmol/L, 3.001 μmol/L, 8.0359 μmol/L in late 1990s respectively and prominent decrease of Si from 4.2614μmol/L in 1980s to 1.5861 μmol/L in late 1990s; the nutrient structure is controlled by nitrogen; the main limiting nutrient is probably silicon;because of the Si limitation the phytoplankton community structure has changed drastically.

  9. DWPF waste glass Product Composition Control System

    Energy Technology Data Exchange (ETDEWEB)

    Brown, K.G.; Postles, R.L.

    1992-07-01

    The Defense Waste Processing Facility (DWPF) will be used to blend aqueous radwaste (PHA) with solid radwaste (Sludge) in a waste receipt vessel (the SRAT). The resulting SRAT material is transferred to the SME an there blended with ground glass (Frit) to produce a batch of melter feed slurry. The SME material is passed to a hold tank (the MFT) which is used to continuously feed the DWPF melter. The melter. The melter produces a molten glass wasteform which is poured into stainless steel canisters for cooling and, ultimately, shipment to and storage in a geologic repository. The Product Composition Control System (PCCS) is the system intended to ensure that the melt will be processible and that the glass wasteform will be acceptable. This document provides a description of this system.

  10. DWPF waste glass Product Composition Control System

    Energy Technology Data Exchange (ETDEWEB)

    Brown, K.G.; Postles, R.L.

    1992-01-01

    The Defense Waste Processing Facility (DWPF) will be used to blend aqueous radwaste (PHA) with solid radwaste (Sludge) in a waste receipt vessel (the SRAT). The resulting SRAT material is transferred to the SME an there blended with ground glass (Frit) to produce a batch of melter feed slurry. The SME material is passed to a hold tank (the MFT) which is used to continuously feed the DWPF melter. The melter. The melter produces a molten glass wasteform which is poured into stainless steel canisters for cooling and, ultimately, shipment to and storage in a geologic repository. The Product Composition Control System (PCCS) is the system intended to ensure that the melt will be processible and that the glass wasteform will be acceptable. This document provides a description of this system.

  11. Fluorescence signatures of an iron-enriched phytoplankton community in the eastern equatorial Pacific Ocean

    Science.gov (United States)

    Hoge, Frank E.; Wayne Wright, C.; Swift, Robert N.; Yungel, James K.; Berry, Richard E.; Mitchell, Richard

    Laser-induced fluorescence profiles of chlorophyll and phycoerythrin pigments and chromophoric dissolved organic matter (CDOM) fluorescence acquired over an iron-enriched phytoplankton patch are compared to profiles made over adjacent, naturally occurring phytoplankton patches. A total of four airborne missions were flown during an 8 day period following the release of the iron-rich fertilizer. Analyses of the airborne laser-induced fluorescence profiles from the upper-ocean layer reveal: (1) Ship-dispersed iron enhances localized phytoplankton production in high-nutrient/low-chlorophyll regions such as found in the eastern equatorial Pacific Ocean. (2) The chlorophyll concentration within the iron-enriched phytoplankton patch exceeded levels of chlorophyll found in naturally occurring phytoplankton patches located outside the enriched region. (3) An increase in phycoerythrin fluorescence was observed within the enriched region in correspondence with the elevated chlorophyll fluorescence. However, the phycoerythrin/chlorophyll fluorescence ratio was lower within the enriched patch than in naturally occurring phytoplankton patches outside of the enriched region. (4) No above-background chromorophoric dissolved organic matter (CDOM) fluorescence was observed in the enriched patch. Elevated CDOM fluorescence was associated with some of the naturally occurring phytoplankton patches outside the enriched region, while other such phytoplankton patches showed no measurable increase in CDOM over background levels. (5) The surface layer manifestation of the patch was observed to be transported to the north and west in close agreement with the drogue positions. No elevated surface layer chlorophyll fluorescence was seen in the vicinity of the ship as it sampled the submerged fraction at the time of the 30 October and 1 November overflights. The phycoerythrin pigment fluorescence emission was insensitive to ambient cloud-induced downwelling irradiance variability, while at the

  12. First steps of ecological restoration in Mediterranean lagoons: Shifts in phytoplankton communities

    Science.gov (United States)

    Leruste, A.; Malet, N.; Munaron, D.; Derolez, V.; Hatey, E.; Collos, Y.; De Wit, R.; Bec, B.

    2016-10-01

    Along the French Mediterranean coast, a complex of eight lagoons underwent intensive eutrophication over four decades, mainly related to nutrient over-enrichment from continuous sewage discharges. The lagoon complex displayed a wide trophic gradient from mesotrophy to hypertrophy and primary production was dominated by phytoplankton communities. In 2005, the implementation of an 11 km offshore outfall system diverted the treated sewage effluents leading to a drastic reduction of anthropogenic inputs of nitrogen and phosphorus into the lagoons. Time series data have been examined from 2000 to 2013 for physical, chemical and biological (phytoplankton) variables of the water column during the summer period. Since 2006, total nitrogen and phosphorus concentrations as well as chlorophyll biomass strongly decreased revealing an improvement in lagoon water quality. In summertime, the decline in phytoplankton biomass was accompanied by shifts in community structure and composition that could be explained by adopting a functional approach by considering the common functional traits of the main algal groups. These phytoplankton communities were dominated by functional groups of small-sized and fast-growing algae (diatoms, cryptophytes and green algae). The trajectories of summer phytoplankton communities displayed a complex response to changing nutrient loads over time. While diatoms were the major group in 2006 in all the lagoons, the summer phytoplankton composition in hypertrophic lagoons has shifted towards green algae, which are particularly well adapted to summertime conditions. All lagoons showed increasing proportion and occurrence of peridinin-rich dinophytes over time, probably related to their capacity for mixotrophy. The diversity patterns were marked by a strong variability in eutrophic and hypertrophic lagoons whereas phytoplankton community structure reached the highest diversity and stability in mesotrophic lagoons. We observe that during the re

  13. Effect of ocean acidification on the nutritional quality of phytoplankton for copepod reproduction

    Science.gov (United States)

    Meyers, M.; Cochlan, W. P.; Kimmerer, W.; Carpenter, E. J.

    2016-02-01

    Phytoplankton are the oceans' primary producers of essential polyunsaturated fatty acids (PUFA), which provide marine organisms with nutrients needed for health and reproduction. It is hypothesized that future ocean acidification (OA) conditions could change the availability of phytoplankton PUFAs for ecologically significant predators such as copepods, affecting their reproductive success. Three species of phytoplankton (Rhodomonas salina, Skeletonema marinoi, Prorocentrum micans) were cultured under present-day (400ppm CO2, pH 8.1) and predicted future (1000ppm CO2, pH 7.8) oceanic conditions. For four days, female Acartia tonsa copepods were fed a phytoplankton mixture from either the present-day or predicted-future treatment. To assess changes in phytoplankton PUFA content, fatty acid profiles were analyzed via capillary gas chromatography. Copepod egg production (EP), hatching success (HS), and egg viability (EV) were determined to assess copepod reproductive success. Fatty acid analysis shows essential PUFAs comprise a smaller percentage of total fatty acids in phytoplankton cultured under high pCO2 (Rho 21.5%; Ske 14.1%; Pro 14.4%) compared to those cultured under present-day pCO2 (Rho 28.8%, Ske 32.7%, Pro 39.3%). Copepod reproduction data demonstrate that females fed phytoplankton cultured under high pCO2 have significantly lower EP (μ=14.3 eggs female-1), HS (μ=35.8%), and EV (μ=12.5%) compared to reproductive success of females fed phytoplankton cultured under present-day CO2 (EP μ=27.0 eggs female-1; HS μ=91.5%; EV μ=96.6%). This study demonstrates that OA can change the nutritional quality of primary producers, which can affect the reproductive success of fundamental secondary consumers.

  14. Bacterial and protist community changes during a phytoplankton bloom

    KAUST Repository

    Pearman, John K.

    2015-10-01

    The present study aims to characterize the change in the composition and structure of the bacterial and microzooplankton planktonic communities in relation to the phytoplankton community composition during a bloom. High-throughput amplicon sequencing of regions of the 16S and 18S rRNA gene was undertaken on samples collected during a 20 day (d) mesocosm experiment incorporating two different nutrient addition treatments [Nitrate and Phosphate (NPc) and Nitrate, Phosphate and Silicate (NPSc)] as well as a control. This approach allowed us to discriminate the changes in species composition across a broad range of phylogenetic groups using a common taxonomic level. Diatoms dominated the bloom in the NPSc treatment while dinoflagellates were the dominant phytoplankton in the control and NPc treatment. Network correlations highlighted significant interactions between OTUs within each treatment including changes in the composition of Paraphysomonas OTUs when the dominant Chaetoceros OTU switched. The microzooplankton community composition responded to changes in the phytoplankton composition while the prokaryotic community responded more to changes in ammonia concentration.

  15. 46 CFR 164.019-13 - Production quality control requirements.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Production quality control requirements. 164.019-13....019-13 Production quality control requirements. (a) General. Each component manufacturer shall establish procedures for maintaining quality control of the materials used in production,...

  16. On the variation of alkalinity during phytoplankton photosynthesis

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available The alkalinity of the organic constituents of marine phytoplankton and their participation in the total alkalinity (TA change of seawater during photosynthesis are carefully assessed. Quantification of the contribution of phytoplankton chlorophyll, proteins and phosphorus compounds to the hydrogen ion balance of seawater in terms of total inorganic nitrogen (∆[NT] = ∆[NH4 +] + ∆[N2] + ∆[NO2 –] + ∆[NO3 –] and total inorganic phosphorus (∆[PT] changes during photosynthesis yielded that the organic components of marine phytoplankton are alkaline by –0.06 × ∆[NT] – 0.49 × ∆[PT], and that the potential total alkalinity (TAP during photosynthesis is TAP = TA – [NH4 –] + 0.93 × [NO2 –] + [NO3 –] + 0.08 × [NT] + 0.23 × [PT] for unfiltered seawater samples and TAP = TA – [NH4 –] + 0.93 × [NO2 –] + [NO3 –] + 0.02 × [NT] + 0.26 × [PT] for filtered seawater samples. These equations correct the traditionally used expression TAP = TA + [NO3 –]. The TAP anomalies are produced, in order of increasing importance, by N2 fixation, DMSP production and CaCO3 fixation.

  17. Physicochemical Flux and Phytoplankton diversity in Shagari ...

    African Journals Online (AJOL)

    USER

    2007-03-20

    Mar 20, 2007 ... environments for the development of phytoplankton communities, which may ... Gawon gulbe which originates partly from River Rima in the northern part of .... may not affect fish as reported by Ayodele and. Ajani (1999).

  18. Marine biogeochemistry: Phytoplankton in a witch's brew

    Science.gov (United States)

    Behrenfeld, Michael

    2016-03-01

    Natural seafloor hydrocarbon seeps are responsible for roughly half of the oil released into the ocean. As these oils and gases rise to the surface, they transport nutrients upwards, benefiting phytoplankton in the upper sunlit layer.

  19. Association between product quality control and process quality control of bulk milk

    NARCIS (Netherlands)

    Velthuis, A.; Asseldonk, van M.A.P.M.

    2010-01-01

    Assessment of dairy-milk quality is based on product quality control (testing bulk-milk samples) and process quality control (auditing dairy farms). It is unknown whether process control improves product quality. To quantify possible association between product control and process control a statisti

  20. Feedback Interactions between Trace Metal Nutrients and Phytoplankton in the Ocean.

    Science.gov (United States)

    Sunda, William G

    2012-01-01

    In addition to control by major nutrient elements (nitrogen, phosphorus, and silicon) the productivity and species composition of marine phytoplankton communities are also regulated by a number of trace metal nutrients (iron, zinc, cobalt, manganese, copper, and cadmium). Of these, iron is most limiting to phytoplankton growth and has the greatest effect on algal species diversity. It also plays an important role in limiting di-nitrogen (N(2)) fixation rates, and thus is important in controlling ocean inventories of fixed nitrogen. Because of these effects, iron is thought to play a key role in regulating biological cycles of carbon and nitrogen in the ocean, including the biological transfer of carbon to the deep sea, the so-called biological CO(2) pump, which helps regulate atmospheric CO(2) and CO(2)-linked global warming. Other trace metal nutrients (zinc, cobalt, copper, and manganese) have lesser effects on productivity; but may exert an important influence on the species composition of algal communities because of large differences in metal requirements among species. The interactions between trace metals and ocean plankton are reciprocal: not only do the metals control the plankton, but the plankton regulate the distributions, chemical speciation, and cycling of these metals through cellular uptake and recycling processes, downward flux of biogenic particles, biological release of organic chelators, and mediation of redox reactions. This two way interaction has influenced not only the biology and chemistry of the modern ocean, but has had a profound influence on biogeochemistry of the ocean and earth system as a whole, and on the evolution of marine and terrestrial biology over geologic history.

  1. Basin-wide distribution of phytoplankton lipids in the South China Sea during intermonsoon seasons: Influence by nutrient and physical dynamics

    Science.gov (United States)

    Dong, Liang; Li, Li; Li, Qianyu; Liu, Jie; Chen, Yuxing; He, Juan; Wang, Hui

    2015-12-01

    Four algal biomarkers, brassicasterol, C30-diol/keto-ol, dinosterol and C37-alkenone, representing diatoms, estigmatophytes, dinoflagellates and coccolithophorids, respectively, were detected in samples collected during two South China Sea cruises to study the modern phytoplankton community structure in the region. For the first time, the basin-wide distribution of these phytoplankton algal biomarkers in the sea surface water during two intermonsoon seasons (spring 2010 and autumn 2011) is documented and charted. Generally, the abundance of the biomass is higher in spring than autumn, with high productivity mostly in the regions of Pearl River estuary, off Palawan and around the Luzon Strait, showing the abundance order: diatoms>estigmatophytes>dinoflagellates>coccolithophorids. We run both redundancy analysis (RDA) and SPSS correlation analysis to interpret the relationship between individual groups and environmental variables. The results indicate that temperature and salinity play a dominant role in controlling the distribution of phytoplankton in these intermonsoon seasons, followed by nitrate playing a secondary role. Our biomarker survey provides important reference data for interpreting paleo-productivity in the geological records in the SCS.

  2. Photophysiological and light absorption properties of phytoplankton communities in the river-dominated margin of the northern Gulf of Mexico

    Science.gov (United States)

    Chakraborty, Sumit; Lohrenz, Steven E.; Gundersen, Kjell

    2017-06-01

    Spatial and temporal variability in photophysiological properties of phytoplankton were examined in relationship to phytoplankton community composition in the river-dominated continental margin of the northern Gulf of Mexico (NGOM). Observations made during five research cruises in the NGOM included phytoplankton photosynthetic and optical properties and associated environmental conditions and phytoplankton community structure. Distinct patterns of spatial and temporal variability in photophysiological parameters were found for waters dominated by different phytoplankton groups. Photophysiological properties for locations associated with dominance by a particular group of phytoplankton showed evidence of photoacclimation as reflected by differences in light absorption and pigment characteristics in relationship to different light environments. The maximum rate of photosynthesis normalized to chlorophyll (PmaxB) was significantly higher for communities dominated (>60% biomass) by cyanobacteria + prochlorophyte (cyano + prochl). The initial slope of the photosynthesis-irradiance (P-E) curve normalized to chlorophyll (αB) was not clearly related to phytoplankton community structure and no significant differences were found in PmaxB and αB between different geographic regions. In contrast, maximum quantum yield of carbon fixation in photosynthesis (Φcmax) differed significantly between regions and was higher for diatom-dominated communities. Multiple linear regression models, specific for the different phytoplankton communities, using a combination of environmental and bio-optical proxies as predictor variables showed considerable promise for estimation of the photophysiological parameters on a regional scale. Such an approach may be utilized to develop size class-specific or phytoplankton group-specific primary productivity models for the NGOM.Plain Language SummaryThis study examined the relationships between phytoplankton community composition and associated

  3. PHYTOPLANKTON OF THE NORTH-SEA AND ITS DYNAMICS - A REVIEW

    NARCIS (Netherlands)

    REID, PC; LANCELOT, C; GIESKES, WWC; HAGMEIER, E; WEICHART, G

    1990-01-01

    Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m-2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of E

  4. PHYTOPLANKTON OF THE NORTH-SEA AND ITS DYNAMICS - A REVIEW

    NARCIS (Netherlands)

    REID, PC; LANCELOT, C; GIESKES, WWC; HAGMEIER, E; WEICHART, G

    1990-01-01

    Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m-2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of

  5. Advanced monitoring and control in biopharmaceutical production

    NARCIS (Netherlands)

    Soons, Z.I.T.A.

    2008-01-01

    Bioprocesses are characterised by natural variability in raw materials, initial conditions, human intervention, and varying properties of the micro-organism. In traditional biopharmaceutical production quality of the product is currently tested at the end of the production process only. Recently the

  6. Production paths – an innovative concept for heavy machinery production planning and control

    OpenAIRE

    R. Lenort; R. Klepek; A. Samolejová; Besta, P.

    2013-01-01

    The paper introduces a new concept for planning and control of complicated heavy machinery production which is based on the principle of „production paths“ – production paths planning and control concept. The concept refl ects the limited applicability of traditional concepts and systems for production planning and control in conditions of heavy machinery industry that is specifi c by the limited repeatability of product structures and volumes, by complicated and variant material ...

  7. Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean

    KAUST Repository

    Coello-Camba, Alexandra

    2017-06-02

    development. This could lead to changes in the blooming phytoplankton community, threatening the production peak and cycles in the Arctic. Our forecasted phytoplankton responses, are constrained by the limited data set, besides uncertainties in the most plausible future Arctic temperature scenarios. To improve predictions in polar oceans, we need to increase the number of studies, in particular for a fast-changing Arctic.

  8. Biological control and sustainable food production

    NARCIS (Netherlands)

    Bale, J.S.; Lenteren, van J.C.; Bigler, F.

    2008-01-01

    The use of biological control for the management of pest insects pre-dates the modern pesticide era. The first major successes in biological control occurred with exotic pests controlled by natural enemy species collected from the country or area of origin of the pest (classical control). Augmentati

  9. Phytoplankton production by remote sensing in the region off Cabo Corrientes, Mexico Producción fitoplanctónica por sensores remotos en la región frente a Cabo Corrientes, México

    Directory of Open Access Journals (Sweden)

    Daffne C. López-Sandoval

    2009-12-01

    Full Text Available Integrated total phytoplankton production (PPmod (grams of carbon per square meter per day, gC m-2 d-1 was calculated for the oceanic region off Cabo Corrientes, Mexico. This was done with semi-analytic models from the literature and using chlorophyll a concentrations (Chl sat and photosynthetically active radiation (PARsat from monthly composites of the satellite sensor SeaWIFS, for May and November 2002, and June 2003. Average values for PPmod had a seasonal variation for the inshore (1.50 and 0.70 gC m-2 d-1 for May and June, and 0.38 for November and the offshore (0.55 and 0.41 gC m-2 d-1 for May and June, and 0.31 for November zones. It is interesting to note that our PPmod data are similar to the previously reported PP14C values for the Cabo Corrientes region. In general, Chl sat and PPmod support the previously reported ship data, which showed intense upwelling conditions during May, an upwelling relaxation period in June, and non-upwelling in November. Estimated PPmod values are within the range of those for other upwelling enriched ecosystems of the Pacific off Mexico.Se calculó la producción integrada del fitoplancton (PPmod (gC m-2 d-1 para la región oceánica frente a Cabo Corrientes, México. Se utilizaron modelos semi-analíticos publicados en la literatura científica, y concentraciones de clorofila a (Chl sat y la radiación fotosinteticamente activa (PARsat de imágenes satelitales compuestas mensuales del sensor SeaWIFS, de mayo y noviembre 2002, y junio 2003. Los valores promedios de PPmod tuvieron una variación estacional en la zona costera (1.50 y 0.70 gC m-2 d-1 para mayo y junio, y 0.38 para noviembre y fuera de la costa (0.55 y 0.41 gC m-2 d-1 para mayo y junio, y 0.31 para noviembre. Los datos de PPmod fueron similares a los valores previamente reportados de PP14C para la región frente a Cabo Corrientes. En general, Chl sat y PPmod concuerdan con los datos publicados previamente, mostrando condiciones intensas de

  10. Effects of lowered pH on marine phytoplankton growth rates

    DEFF Research Database (Denmark)

    Berge, Terje; Daugbjerg, Niels; Andersen, Betinna Balling

    2010-01-01

    concentration of seawater. Ocean acidification may potentially both stimulate and reduce primary production by marine phytoplankton. Data are scarce on the response of marine phytoplankton growth rates to lowered pH/increased CO2. Using the acid addition method to lower the seawater pH and manipulate...... the carbonate system, we determined in detail the lower pH limit for growth rates of 2 model species of common marine phytoplankton. We also tested whether growth and production rates of 6 other common species of phytoplankton were affected by ocean acidification (lowered to pH 7.0). The lower pH limits...... statistically similar in the pH range of ~7.0 to 8.5. Our results and literature reports on growth at lowered pH indicate that marine phytoplankton in general are resistant to climate change in terms of ocean acidification, and do not increase or decrease their growth rates according to ecological relevant...

  11. Mixing and phytoplankton dynamics in a submarine canyon in the West Antarctic Peninsula

    Science.gov (United States)

    Carvalho, Filipa; Kohut, Josh; Oliver, Matthew J.; Sherrell, Robert M.; Schofield, Oscar

    2016-07-01

    Bathymetric depressions (canyons) exist along the West Antarctic Peninsula shelf and have been linked with increased phytoplankton biomass and sustained penguin colonies. However, the physical mechanisms driving this enhanced biomass are not well understood. Using a Slocum glider data set with over 25,000 water column profiles, we evaluate the relationship between mixed layer depth (MLD, estimated using the depth of maximum buoyancy frequency) and phytoplankton vertical distribution. We use the glider deployments in the Palmer Deep region to examine seasonal and across canyon variability. Throughout the season, the ML becomes warmer and saltier, as a result of vertical mixing and advection. Shallow ML and increased stratification due to sea ice melt are linked to higher chlorophyll concentrations. Deeper mixed layers, resulting from increased wind forcing, show decreased chlorophyll, suggesting the importance of light in regulating phytoplankton productivity. Spatial variations were found in the canyon head region where local physical water column properties were associated with different biological responses, reinforcing the importance of local canyon circulation in regulating phytoplankton distribution in the region. While the mechanism initially hypothesized to produce the observed increases in phytoplankton over the canyons was the intrusion of warm, nutrient enriched modified Upper Circumpolar Deep Water (mUCDW), our analysis suggests that ML dynamics are key to increased primary production over submarine canyons in the WAP.

  12. Phytoplankton growth rate and nitrogen content: Implications for feeding and fecundity in a herbivorous copepod

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    1989-01-01

    at a concentration of 1.5 ppm. Over more than 2 orders of magnitude increase in algal growth rate, the ingested cell volume increased by less than a factor of 2, ingested carbon remained constant whereas ingested nitrogen as well as rate of egg production increased by a factor of ca 6. Variation in ingested cell......Observations of natural feeding and egg-production rates of planktonic copepods have revealed distinct responses, independent of phytoplankton biomass, to oceanographic processes that fertilize the photic layer. Are such responses caused by changes in phytoplankton growth rate, influencing feeding...... behaviour, and/or by changes in the chemical composition of the phytoplankton, influencing fecundity? The diatom Thalassiosira weissflogii, grown in continuous cultures at different dilution rates and different nitrogen concentrations in the growth medium, was offered to the copepod Acartia tonsa...

  13. SynSen PFT: Synergistic Retrieval of Phytoplankton Functional Types from Space From Hyper-and Multispectral Measurements

    Science.gov (United States)

    Soppa, Mariana A.; Loza, Svetlana N.; Dinter, Tilman; Wolanin, Aleksandra; Bricaud, Annick; Brewein, Robert; Rozanov, Vladimir; Barcher, Astrid

    2016-08-01

    To gain knowledge on the role of marine phytoplankton in the global marine ecosystem and biogeochemical cycles, information on the global distribution of major phytoplankton functional types is essential. The Synergistic Retrieval of Phytoplankton Functional Types from Space from Hyper- and Multispectral Measurements project (SynSenPFT) aims to improve the retrieval of phytoplankton types (PFTs) from space by exploring the synergistic use of low-spatial-hyper- spectral and high-spatial-multi-spectral satellite data. Three PFTs are investigated: diatoms, coccolithophores and cyanobacteria. The work involves the improvement/revision of existing PFT algorithms based on hyper- (PhytoDOAS, [1]) and multi-spectral (OC- PFT, [2]) datasets, development of synergistic PFT products combining the retrievals of these two algorithms and intercomparison of the synergistic PFT products with those derived from other methods [3,4,5].

  14. Natural products and body weight control

    Directory of Open Access Journals (Sweden)

    Jay Lee

    2011-01-01

    Full Text Available The purpose of the review was to summarise the effect of some commonly available natural products used for body weight management. We collected data from PubMed and scientific journals. There are numerous publications on this topic, however we have summarized the most commonly available and potent natural products from recent 53 publications. The natural products analyzed in this paper include catechins, capsaicin, conjugated linoleic acid, fucoxanthin, soy isoflavone, glabridin, astaxanthin and cyaniding-3-glucoside. These natural products are effective and safe for body weight management. Further studies need to be conducted to investigate the mechanism of action, metabolism, long term safety and side effects of these natural products, as well as interactions between these natural products with dietary components.

  15. Distributions of chlorophyll a and carbon fixed strength of phytoplankton in autumn of the southern Huanghai Sea waters

    Institute of Scientific and Technical Information of China (English)

    ZHENG Guoxia; SONG Jinming; DAI Jicui; WANG Yiming

    2006-01-01

    Chlorophyll a (Chl a) concentration and primary productivity (PP), namely, carbon fixed strength of phytoplankton along four transects in the southern Huanghai Sea (SHS) were studied for their distribution features and controlling mechanisms based on the investigations from 17 October to 3 November 2005. The Chl a concentration in the study waters dynamically changed spatially.Surface Chl a concentrations ranged from 0.11 to 2.38 mg/m3 with higher and lower values observed in the nutrient-laden inshore waters and central part of the SHS occupied by oligotrophic current, respectively. The vertical distribution of Chl a concentration showed a predominant pattern of subsurface concentration maximum profile. It followed the previous result of the deep dissolved oxygen concentration maximum profile, which was significantly correlated with phytoplankton and regional water mass. The primapecially phosphate concentration in seawater and hydrological condition. Furthermore, associating the present study results together with previous studies, the annual value of carbon fixed production of phytoplankton in the entire marginal seas of East China(including the Bohai Sea, the Huanghai Sea and the East China Sea) was estimated to be 222 Mt, which accounted for 2% of that in the global margins. Besides, it was as 16.2 times as the annual value of apparent carbon sink strength ( 13.96 Mt) in the marginal seas of East China. This multiple was different in different sea areas (3.0 in the Bohai Sea, 6.7 in the Huanghai Sea and 81.6 in the East China Sea).

  16. Influence of Vitamin B Auxotrophy on Nitrogen Metabolism in Eukaryotic Phytoplankton

    Directory of Open Access Journals (Sweden)

    Erin M Bertrand

    2012-10-01

    Full Text Available While nitrogen availability is known to limit primary production in large parts of the ocean, vitamin starvation amongst eukaryotic phytoplankton is becoming increasingly recognized as an oceanographically relevant phenomenon. Cobalamin (B12 and thiamine (B1 auxotrophy are widespread throughout eukaryotic phytoplankton, with over 50% of cultured isolates requiring B12 and 20% requiring B1. The frequency of vitamin auxotrophy in harmful algal bloom species is even higher. Instances of colimitation between nitrogen and B vitamins have been observed in marine environments, and interactions between these nutrients have been shown to impact phytoplankton species composition. This review evaluates the potential for interactive effects of nitrogen and vitamin B12 and B1 starvation in eukaryotic phytoplankton. B12 plays essential roles in amino acid and one-carbon metabolism, while B1 is important for primary carbohydrate and amino acid metabolism and likely useful as an anti-oxidant. Here we will focus on three potential metabolic interconnections between vitamin, nitrogen and sulfur metabolism that may have ramifications for the role of vitamin and nitrogen scarcities in driving ocean productivity and species composition. These include: (1 B12, B1, and N starvation impacts on osmolyte and antioxidant production, (2 B12 and B1 starvation impacts on polyamine biosynthesis, and (3 influence of B12 and B1 starvation on the diatom urea cycle and amino acid recycling through impacts on the citric acid cycle. We evaluate evidence for these interconnections and identify oceanographic contexts in which each may impact rates of primary production and phytoplankton community composition. Major implications include that B12 and B1 deprivation may impair the ability of phytoplankton to recover from nitrogen starvation and that changes in vitamin and nitrogen availability may synergistically impact harmful algal bloom formation.

  17. Effects of nutrients and zooplankton on the phytoplankton community structure in Marudu Bay

    Science.gov (United States)

    Tan, Kar Soon; Ransangan, Julian

    2017-07-01

    Current study was carried out to provide a better understanding on spatial and temporal variations in the phytoplankton community structure in Marudu Bay, an important nursery ground for fishery resources within the Tun Mustapha Marine Park and Coral Triangle Initiative, and their relationship with environmental variables. Samplings were conducted monthly from April 2014 to April 2015 in Marudu Bay, Malaysia. Water samples were collected for nutrients analysis, zooplankton and phytoplankton counting. Moreover, the in situ environmental parameters were also examined. The field study showed a total of forty seven phytoplankton genera, representative of 33 families were identified. The nutrient concentrations in Marudu Bay was low (mesotrophic) throughout the year, where the phytoplankton community was often dominated by Chaetoceros spp. and Bacteriastrum spp. In general, increase in nitrate concentration triggered the bloom of centric diatom, Chaetoceros spp. and Bacteriastrum spp. in Marudu Bay. However, the bloom of these phytoplankton taxa did not occur in the presence of high ammonia concentration. In addition, high abundance of zooplankton also a limiting factor of the phytoplankton blooms particularly at end of southwest monsoon. High silica concentration promoted the growth of pennate diatoms, Proboscia spp. and Thallassionema spp., but the depletion of silica quickly terminated the bloom. Interestingly, our study showed that Chaetoceros spp., tolerated silica depletion condition, but the average cell size of this taxon reduced significantly. In summary, the phytoplankton community structure in mesotrophic environment is more sensitive to the changes in zooplankton abundance, nutrient concentration and its ratio than that in nutrient rich environments. This study also recommends that bivalve farming at industrial scale is not recommended in Marudu Bay because it potentially depletes the primary productivity hence jeopardizing the availability of live food for

  18. Underlying Factors for Practicality of the Production Control Systems

    DEFF Research Database (Denmark)

    Arica, Emrah; Strandhagen, Jan Ola; Hvolby, Hans-Henrik

    2012-01-01

    This paper gives indications to important factors that must be considered for effectiveness of the production control systems under uncertainty. Five key factors have been identified by the literature study. Production schedule generation and execution approach under uncertainty, information...

  19. Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate

    Science.gov (United States)

    Charlson, Robert J.; Warren, Stephen G.; Lovelock, James E.; Andreae, Meinrat O.

    1987-04-01

    The major source of cloud-condensation nuclei (CCN) over the oceans appears to be dimethylsulphide, which is produced by planktonic algae in sea water and oxidizes in the atmosphere to form a sulphate aerosol. Because the reflectance (albedo) of clouds (and thus the earth's radiation budget) is sensitive to CCN density, biological regulation of the climate is possible through the effects of temperature and sunlight on phytoplankton population and dimethylsulphide production. To counteract the warming due to doubling of atmospheric CO2, an approximate doubling of CCN would be needed.

  20. Phytoplankton Bloom in North Sea off Scotland

    Science.gov (United States)

    2008-01-01

    The northern and western highlands of Scotland were still winter-brown and even dusted with snow in places, but the waters of the North Sea were blooming with phytoplankton on May 8, 2008, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite passed over the region and captured this image. The tiny, plant-like organisms swirled in the waters off the country's east coast, coloring the shallow coastal waters shades of bright blue and green. Phytoplankton are tiny organisms--many are just a single cell--that use chlorophyll and other pigments to capture light for photosynthesis. Because these pigments absorb sunlight, they change the color of the light reflected from the sea surface back to the satellite. Scientists have used observations of 'ocean color' from satellites for more than 20 years to track worldwide patterns in phytoplankton blooms. Phytoplankton are important to the Earth system for a host of reasons, including their status as the base of the ocean food web. In the North Sea, they are the base of the food web that supports Scotland's commercial fisheries, including monkfish and herring. As photosynthesizers, they also play a crucial role in the carbon cycle, removing carbon dioxide from the atmosphere. Some oceanographers are concerned that rising ocean temperatures will slow phytoplankton growth rates, harming marine ecosystems and causing carbon dioxide to accumulate more rapidly in the atmosphere.

  1. Phytoplankton community and environmental correlates in a coastal upwelling zone along western Taiwan Strait

    Science.gov (United States)

    Wang, Yu; Kang, Jian-hua; Ye, You-yin; Lin, Geng-ming; Yang, Qing-liang; Lin, Mao

    2016-02-01

    Upwelling system in western Taiwan Strait is important for facilitating the fishery production. This study investigated hydro-chemical properties, phytoplankton biomass, phytoplankton species composition, three-dimensional (horizontal, vertical and transect) distribution of phytoplankton abundance, as well as phytoplankton annual variation and the correlation of phytoplankton community with the upwelling of underlying current and nutrients according to samples of Fujian-Guangdong coastal upwelling zone in western Taiwan Strait from August 27 to September 8, 2009. The results manifest that the nutrient-rich cold and high salinity current on the continental shelf of South China Sea upwells to the Fujian-Guangdong coastal waters through Taiwan Bank and the surging strength to surface is weak while strong at 30-m layer. The thermohaline center of coastal upwelling shifts to the east of Dongshan Island and expanded to offshore waters in comparison with previous records. A total of 137 phytoplankton species belonging to 59 genera in 4 phyla are identified excluding the unidentified species. Diatom is the first major group and followed by dinoflagellate. Cyanobacteria mainly composed by three Trichodesmium species account for a certain proportions, while Chrysophyta are only found in offshore waters. The dominant species include Thalassionema nitzschioides, Pseudo-nitzschia pungens, Thalassionema frauenfeldii, Pseudo-nitzschia delicatissima, Rhizosolenia styliformis, Chaetoceros curvisetus, Diplopsalis lenticula and Trichodesmium thiebautii. Phytoplankton community mainly consists of eurythermal and eurytopic species, followed by warm-water species, tropic high-salinity species and oceanic eurythermic species in order. Phytoplankton abundance ranges from 1.00 × 102 ind./L ~ 437.22 × 102 ind./L with an average of 47.36 × 102 ind./L. For vertical distribution, maximum abundance is found at 30 m-depth and the surface comes second. Besides, the abundance below 30 m

  2. SOME ENVIRONMENTAL FEATURES OF PHYTOPLANKTON

    Directory of Open Access Journals (Sweden)

    Taha A. Al-Tayyar

    2013-05-01

    Full Text Available Todefine the biological features of phytoplankton in Mosul  Dam  Lake, monthly samples were collectedalong a year from September 2003 to August 2004. Consisting thermalstratification and turn over periods from four locations in the main lake andanother location in the regulating lake. Total numbers of algae  reached 2300 cell/ml in the main lake and 1100cell/ml in the regulating lake.Bacillariophyta were dominant with a maximum number of 1400 cell/ml in autumn. Chlorophytawere dominant in autumn also with 550 cell/ml. Ten genus of Chlorophyta wereappeared in this water body: Cosmarium, Chlorella, Spirogyra, Scendesmus, Pediastrum, Tetraedron, Quadrigula, Ankiseradosm, Pandorina, and Straurastrum.Seven genus of Bacillariophyta were noticeable. Some genus of Cyanophyta was recorded as Aphanocapsa. In addition someEuglenophyta spp. were occurred in the main lake and the regulating lake also. On thebasis of these algae abundance, the lake is undergoing cultural Eutrophication.It has passed in mesotrophic state (the middle trophic state ofEutrophication. Some genera which were appeared are the indication ofeutrophic state.Totalplate count bacteria ranged from 400-1700 cell/ ml in the main lake and 200-950 cell/ml in the regulating lakewere also recorded. Coliform bacteria were founded with most probablenumber  reached 460 cell/100ml in themain lake and 150 cell/100ml in the regulating lake. Therefore, the lake wateris classified as moderate pure and considering a good source of raw water supplywith all treatment units and safe for swimming and recreational uses.

  3. Direct product quality control for energy efficient climate controlled transport of agro-material

    NARCIS (Netherlands)

    Verdijck, G.J.C.; Preisig, H.A.; Straten, van G.

    2005-01-01

    A (model-based) Product Quality Controller is presented for climate controlled operations involving agro-material, such as storage and transport. This controller belongs to the class of Model Predictive Controllers and fits in a previously developed hierarchical control structure. The new Product

  4. Speech production as state feedback control.

    Science.gov (United States)

    Houde, John F; Nagarajan, Srikantan S

    2011-01-01

    Spoken language exists because of a remarkable neural process. Inside a speaker's brain, an intended message gives rise to neural signals activating the muscles of the vocal tract. The process is remarkable because these muscles are activated in just the right way that the vocal tract produces sounds a listener understands as the intended message. What is the best approach to understanding the neural substrate of this crucial motor control process? One of the key recent modeling developments in neuroscience has been the use of state feedback control (SFC) theory to explain the role of the CNS in motor control. SFC postulates that the CNS controls motor output by (1) estimating the current dynamic state of the thing (e.g., arm) being controlled, and (2) generating controls based on this estimated state. SFC has successfully predicted a great range of non-speech motor phenomena, but as yet has not received attention in the speech motor control community. Here, we review some of the key characteristics of speech motor control and what they say about the role of the CNS in the process. We then discuss prior efforts to model the role of CNS in speech motor control, and argue that these models have inherent limitations - limitations that are overcome by an SFC model of speech motor control which we describe. We conclude by discussing a plausible neural substrate of our model.

  5. Speech production as state feedback control

    Directory of Open Access Journals (Sweden)

    John F Houde

    2011-10-01

    Full Text Available Spoken language exists because of a remarkable neural process. Inside a speaker’s brain, an intended message gives rise to neural signals activating the muscles of the vocal tract. The process is remarkable because these muscles are activated in just the right way that the vocal tract produces sounds a listener understands as the intended message. What is the best approach to understanding the neural substrate of this crucial motor control process? One of the key recent modeling developments in neuroscience has been the use of state feedback control (SFC theory to explain the role of the CNS in motor control. SFC postulates that the CNS controls motor output by (1 estimating the current dynamic state of the thing (e.g., arm being controlled, and (2 generating controls based on this estimated state. SFC has successfully predicted a great range of non-speech motor phenomena, but as yet has not received attention in the speech motor control community. Here, we review some of the key characteristics of speech motor control and what they say about the role of the CNS in the process. We then discuss prior efforts to model the role of CNS in speech motor control, and argue that these models have inherent limitations – limitations that are overcome by an SFC model of speech motor control which we describe. We conclude by discussing a plausible neural substrate of our model.

  6. Production Quality Control Of Microfluidic Chip Designs

    DEFF Research Database (Denmark)

    Calaon, Matteo; Hansen, Hans Nørgaard; Tosello, Guido

    2012-01-01

    process chain, test geometries were designed and produced on the side of the functional features. The so called “Finger Print” of the lithography and molding processes was qualitatively and quantitatively evaluated through scanning electron microscopy and atomic force microscopy respectively. The entire......The challenge of fabricating geometries with critical dimensions ranging from few microns down to 10 nanometers with high production rate is delaying the development of nanotechnology based products. Diverse research works have shown the capability of technologies such as UV lithography, nano...... imprint lithography and e-beam lithography to produce micro and nano features. However, their application for tooling purposes is relatively new and the potential to produce nanometer features with high volume low cost production is enormous. Considering possible implementation in a mass production...

  7. Phytoplankton can actively diversify their migration strategy in response to turbulent cues

    Science.gov (United States)

    Sengupta, Anupam; Carrara, Francesco; Stocker, Roman

    2017-03-01

    Marine phytoplankton inhabit a dynamic environment where turbulence, together with nutrient and light availability, shapes species fitness, succession and selection. Many species of phytoplankton are motile and undertake diel vertical migrations to gain access to nutrient-rich deeper layers at night and well-lit surface waters during the day. Disruption of this migratory strategy by turbulence is considered to be an important cause of the succession between motile and non-motile species when conditions turn turbulent. However, this classical view neglects the possibility that motile species may actively respond to turbulent cues to avoid layers of strong turbulence. Here we report that phytoplankton, including raphidophytes and dinoflagellates, can actively diversify their migratory strategy in response to hydrodynamic cues characteristic of overturning by Kolmogorov-scale eddies. Upon experiencing repeated overturning with timescales and statistics representative of ocean turbulence, an upward-swimming population rapidly (5-60 min) splits into two subpopulations, one swimming upward and one swimming downward. Quantitative morphological analysis of the harmful-algal-bloom-forming raphidophyte Heterosigma akashiwo together with a model of cell mechanics revealed that this behaviour was accompanied by a modulation of the cells’ fore-aft asymmetry. The minute magnitude of the required modulation, sufficient to invert the preferential swimming direction of the cells, highlights the advanced level of control that phytoplankton can exert on their migratory behaviour. Together with observations of enhanced cellular stress after overturning and the typically deleterious effects of strong turbulence on motile phytoplankton, these results point to an active adaptation of H. akashiwo to increase the chance of evading turbulent layers by diversifying the direction of migration within the population, in a manner suggestive of evolutionary bet-hedging. This migratory

  8. Grazing impact of microzooplankton on phytoplankton in the Xiamen Bay using pigment-specific dilution technique

    Institute of Scientific and Technical Information of China (English)

    HUANG Bangqin; LIU Yuan; XIANG Weiguo; TIAN Haojie; LIU Hongbin; CAO Zhenrui; HONG Huasheng

    2008-01-01

    Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography (HPLC) in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d -1 with the highest value occurred in the inner bay in May. Microzooplankton grazing rates ranged from 0.5 to 3.1 d-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate (up to 3.3 d -1 ) was recorded for diatoms in August, while the maximum grazing rate ( up to 2.1 d -1 ) was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes (83%) in August, while the maximum grazing pressure on primary production was observed for cyanobacteria (up to 151% ) in December in the inner bay. Net growth rates of larger phytoplanktons (diatoms and dinoflagellates) were higher than those of smaller groups (prasinophytes, chlorophytes and cyanobacteria). Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons ( December and February).

  9. Connections between the growth of Arctica islandica and phytoplankton dynamics on the Faroe Shelf

    Science.gov (United States)

    Bonitz, Fabian; Andersson, Carin; Trofimova, Tamara

    2017-04-01

    In this study we use molluscan sclerochronological techniques in order to obtain closer insights into environmental and ecological dynamics of Faroe Shelf waters. The Faroe Shelf represents a special ecosystem with rich benthic and neritic communities, which also have great importance for many economically relevant fish stocks. Thus, a better understanding of seasonal and year-to-year phytoplankton and stratification dynamics would be useful because they also have implications for higher trophic levels. The water masses of the Faroe Shelf are fairly homogenous and isolated from off-shelf waters but at a certain depth, which is referred to as transition zone, seasonal stratification and horizontal exchange occur. Systematic observations and phytoplankton dynamic investigations have only been performed during the last 29 years but longer records are missing. Thus, we use the growth increment variability in long-lived Arctica islandica shells from the transition zone of the eastern Faroe Shelf to evaluate its potential to estimate on-shelf phytoplankton and stratification dynamics since previous studies have shown that the growth of A. islandica is highly dependent on food availability. We have built a shell-based master-chronology reaching back to the 17th century. Comparisons between the growth indices of our chronology and fluorescence data reveal significant positive relationships. In combination with an index that accounts for stratification even stronger correlations are obtained. This indicates that the growth of A. islandica is largely influenced by a combination of how much phytoplankton is produced and how much actually reaches the bottom, i.e. how well-mixed the water column is. Further significant positive correlations can also be found between the growth indices and other primary productivity data from the Faroe Shelf. In conclusion, our results suggest that the growth indices can be related to year-to-year changes in phytoplankton production and

  10. Seasonal carbon uptake rates of phytoplankton in the northern East/Japan Sea

    Science.gov (United States)

    Lee, Sang Heon; Joo, HuiTae; Lee, Jae Hyung; Lee, Jang Han; Kang, Jae Joong; Lee, Ho Won; Lee, Dabin; Kang, Chang Keun

    2017-09-01

    Korea-Russia joint expeditions have been conducted mainly in the less studied Russian sector of the East/Japan Sea to understand the physical and ecological structures. In this study, the carbon uptake rates of phytoplankton measured in 2012 (middle-late October) and 2015 (middle April-early May) were analyzed to understand seasonal and spatial distributions of phytoplankton production, using a 13C-15N dual isotope tracer technique. The water columns in the euphotic layers were well mixed during our cruise periods in both years. The water column-integrated chl-a concentrations (mean ± S.D. = 2.28 ± 1.47 mg m-3) in 2015 was significantly higher (t-test, p 20 μm) was observed near the Russian coast. The daily carbon uptake rates in this study were 180.5 and 441.6 mg C m-2 d-1 in 2012 and 2015, respectively which are significantly (t-test, p Japan Sea (863 ± 679.6 mg C m-2 d-1). The potential reasons for the lower rate in this study are discussed. The small phytoplankton contribution (47.4%) averaged from the two different cruises in this study is consistent with the result (47%) reported in temperate regions. Moreover, a significantly (t-test, p < 0.01) lower contribution of small phytoplankton in total primary production than total phytoplankton biomass in this study is consistent with the results from other regions. Lower total primary production might be expected due to increasing contribution of small phytoplankton under warmer conditions.

  11. Biomass relations between phytoplankton and zooplankton in Goa waters

    Digital Repository Service at National Institute of Oceanography (India)

    Pant, A.; Matondkar, S.G.P.; Goswami, S.C.

    Biomass of phytoplankton and zooplankton, measured as particulate oxidizable carbon, shows that at shallowest stations (5 m) there is large excess of phytoplankton organic carbon over zooplankton carbon in all the samples There is no significant...

  12. Phytoplankton biovolume is independent from the slope of the size spectrum in the oligotrophic atlantic ocean

    KAUST Repository

    Moreno-Ostos, Enrique

    2015-08-06

    Modelling the size-abundance spectrum of phytoplankton has proven to be a very useful tool for the analysis of physical-biological coupling and the vertical flux of carbon in oceanic ecosystems at different scales. A frequent observation relates high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does not correspond with measurements of the phytoplankton community in the Atlantic Ocean open waters. As part of the Malaspina Circunnavegation Expedition, sixty seven sampling stations within the Atlantic Ocean covering six oceanographic provinces, at different seasons, produced a complete set of phytoplankton size-spectra whose slope and biovolume did not show any obvious interrelation. In these oligotrophic sites, small (procaryotes) and medium-size (nanoplankton) cells are responsible for the most part of biovolume, and their response to environmental conditions does not apply to changes in the size-abundance spectrum slope as expected in richer, large-cell dominated ecosystems.

  13. Annual boom-bust cycles of polar phytoplankton biomass revealed by space-based lidar

    Science.gov (United States)

    Behrenfeld, Michael J.; Hu, Yongxiang; O'Malley, Robert T.; Boss, Emmanuel S.; Hostetler, Chris A.; Siegel, David A.; Sarmiento, Jorge L.; Schulien, Jennifer; Hair, Johnathan W.; Lu, Xiaomei; Rodier, Sharon; Scarino, Amy Jo

    2017-02-01

    Polar plankton communities are among the most productive, seasonally dynamic and rapidly changing ecosystems in the global ocean. However, persistent cloud cover, periods of constant night and prevailing low solar elevations in polar regions severely limit traditional passive satellite ocean colour measurements and leave vast areas unobserved for many consecutive months each year. Consequently, our understanding of the annual cycles of polar plankton and their interannual variations is incomplete. Here we use space-borne lidar observations to overcome the limitations of historical passive sensors and report a decade of uninterrupted polar phytoplankton biomass cycles. We find that polar phytoplankton dynamics are categorized by `boom-bust' cycles resulting from slight imbalances in plankton predator-prey equilibria. The observed seasonal-to-interannual variations in biomass are predicted by mathematically modelled rates of change in phytoplankton division. Furthermore, we find that changes in ice cover dominated variability in Antarctic phytoplankton stocks over the past decade, whereas ecological processes were the predominant drivers of change in the Arctic. We conclude that subtle and environmentally driven imbalances in polar food webs underlie annual phytoplankton boom-bust cycles, which vary interannually at each pole.

  14. Annual boom-bust cycles of polar phytoplankton biomass revealed by space-based lidar

    Science.gov (United States)

    Behrenfeld, Michael J.; Hu, Yongxiang; O'Malley, Robert T.; Boss, Emmanuel S.; Hostetler, Chris A.; Siegel, David A.; Sarmiento, Jorge L.; Schulien, Jennifer; Hair, Johnathan W.; Lu, Xiaomei; Rodier, Sharon; Scarino, Amy Jo

    2016-12-01

    Polar plankton communities are among the most productive, seasonally dynamic and rapidly changing ecosystems in the global ocean. However, persistent cloud cover, periods of constant night and prevailing low solar elevations in polar regions severely limit traditional passive satellite ocean colour measurements and leave vast areas unobserved for many consecutive months each year. Consequently, our understanding of the annual cycles of polar plankton and their interannual variations is incomplete. Here we use space-borne lidar observations to overcome the limitations of historical passive sensors and report a decade of uninterrupted polar phytoplankton biomass cycles. We find that polar phytoplankton dynamics are categorized by `boom-bust' cycles resulting from slight imbalances in plankton predator-prey equilibria. The observed seasonal-to-interannual variations in biomass are predicted by mathematically modelled rates of change in phytoplankton division. Furthermore, we find that changes in ice cover dominated variability in Antarctic phytoplankton stocks over the past decade, whereas ecological processes were the predominant drivers of change in the Arctic. We conclude that subtle and environmentally driven imbalances in polar food webs underlie annual phytoplankton boom-bust cycles, which vary interannually at each pole.

  15. Availability of iron for phytoplankton growth in the north-east Atlantic

    Science.gov (United States)

    Blain, S.; Guieu, C.; Claustre, H.; Leblanc, K.; Moutin, T.; Quéguiner, B.; Sarthou, G.

    2003-04-01

    We present results from a cruise (February March 2001, Programme Océanographique Multi disciplinaire Meso-echelle POMME) in the north east Atlantic between Azore and Portugal (39N--44N, 17--21W). The studied area was characterised by high mesoscale activities. The availability of iron for phytoplankton was studied using deck incubation experiments. On a qualitative point of view, experiments demonstrated that dissolved iron concentration was limiting the primary production in spring. For diatoms a simultaneous limitation by silicic acid has been also observed. The availability of iron has been manipulated using desferral ligand (DFOB). Addition of DFOB clearly reduced the growth of the phytoplankton community showing that a large part of the ambient iron was bioavailable. However our results confirm also previous works showing that a small growth of the phytoplankton community is possible even if DFOB is added. Based on pigment analysis we determined the half saturation constant for different phytoplankton groups. Estimated values were 0.2 nM for micro- and nano-phytoplankton and and much lower for picoplankton.

  16. Seasonal change of phytoplankton (spring vs. summer) in the southern Patagonian shelf

    Science.gov (United States)

    Gonçalves-Araujo, Rafael; de Souza, Márcio Silva; Mendes, Carlos Rafael Borges; Tavano, Virginia Maria; Garcia, Carlos A. E.

    2016-08-01

    As part of the Patagonian Experiment (PATEX) project two sequential seasons (spring/summer 2007-2008) were sampled in the southern Patagonian shelf, when physical-chemical-biological (phytoplankton) data were collected. Phytoplankton biomass and community composition were assessed through both microscopic and high-performance liquid chromatography/chemical taxonomy (HPLC/CHEMTAX) techniques and related to both in situ and satellite data at spatial and seasonal scales. Phytoplankton seasonal variation was clearly modulated by water column thermohaline structure and nutrient dynamics [mainly dissolved inorganic nitrogen (DIN) and silicate]. The spring phytoplankton community showed elevated biomass and was dominated by diatoms [mainly Corethron pennatum and small (bloom. In contrast, the phytoplankton community in summer presented lower biomass and was mainly dominated by haptophytes (primarily Emiliania huxleyi and Phaeocystis antarctica) and dinoflagellates, associated with shallower and well-stratified upper mixed layers with higher nutrient concentrations, likely due to lateral advection of nutrient-rich waters from the Malvinas Current. The gradual establishment of a strongly stratified and shallow UMLD as season progressed, was an important factor leading to the replacement of the spring diatom community by a dominance of calcifying organisms, as shown in remote sensing imagery and confirmed by microscopic examination. Furthermore, in spring, phaeopigments a (degradation products of chlorophyll a) relative to chlorophyll a, were twice that of summer, indicating the diatom bloom was under higher grazing pressure.

  17. Imaging flow cytometry for phytoplankton analysis.

    Science.gov (United States)

    Dashkova, Veronika; Malashenkov, Dmitry; Poulton, Nicole; Vorobjev, Ivan; Barteneva, Natasha S

    2017-01-01

    This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments.

  18. Iron-nutrient interactions within phytoplankton

    Directory of Open Access Journals (Sweden)

    Hanan Schoffman

    2016-08-01

    Full Text Available Iron limits photosynthetic activity in up to one third of the world’s oceans and in many fresh water environments. When studying the effects of Fe limitation on phytoplankton or their adaptation to low Fe environments, we must take into account the numerous cellular processes within which this micronutrient plays a central role. Due to its flexible redox chemistry, Fe is indispensable in enzymatic catalysis and electron transfer reactions and is therefore closely linked to the acquisition, assimilation and utilization of essential resources. Iron limitation will therefore influence a wide range of metabolic pathways within phytoplankton, most prominently photosynthesis. In this review we map out four well-studied interactions between Fe and essential resources: nitrogen, manganese, copper and light. Data was compiled from both field and laboratory studies to shed light on larger scale questions such as the connection between metabolic pathways and ambient iron levels and the biogeographical distribution of phytoplankton species.

  19. Interaction and signalling between a cosmopolitan phytoplankton and associated bacteria

    Science.gov (United States)

    Amin, S. A.; Hmelo, L. R.; van Tol, H. M.; Durham, B. P.; Carlson, L. T.; Heal, K. R.; Morales, R. L.; Berthiaume, C. T.; Parker, M. S.; Djunaedi, B.; Ingalls, A. E.; Parsek, M. R.; Moran, M. A.; Armbrust, E. V.

    2015-06-01

    Interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape ecosystem diversity. In marine ecosystems, these interactions are difficult to study partly because the major photosynthetic organisms are microscopic, unicellular phytoplankton. Coastal phytoplankton communities are dominated by diatoms, which generate approximately 40% of marine primary production and form the base of many marine food webs. Diatoms co-occur with specific bacterial taxa, but the mechanisms of potential interactions are mostly unknown. Here we tease apart a bacterial consortium associated with a globally distributed diatom and find that a Sulfitobacter species promotes diatom cell division via secretion of the hormone indole-3-acetic acid, synthesized by the bacterium using both diatom-secreted and endogenous tryptophan. Indole-3-acetic acid and tryptophan serve as signalling molecules that are part of a complex exchange of nutrients, including diatom-excreted organosulfur molecules and bacterial-excreted ammonia. The potential prevalence of this mode of signalling in the oceans is corroborated by metabolite and metatranscriptome analyses that show widespread indole-3-acetic acid production by Sulfitobacter-related bacteria, particularly in coastal environments. Our study expands on the emerging recognition that marine microbial communities are part of tightly connected networks by providing evidence that these interactions are mediated through production and exchange of infochemicals.

  20. Nitrogen and phosphorus intake by phytoplankton in the Xiamen Bay

    Institute of Scientific and Technical Information of China (English)

    林彩; 林辉; 贺青; 许焜灿; 吴省三; 张元标; 陈金民; 陈宝红; 林力斌; 卢美鸾; 陈维芬; 汤荣坤; 暨卫东

    2010-01-01

    This paper describes a time series experiment examining the nitrogen and phosphorus intake of natural phytoplankton communities by a microcosms approach.Seawater samples containing natural phytoplankton communities were collected from waters around Baozhu Islet in inner Xiamen Bay and around Qingyu Islet in the outer bay.The goal was to elucidate the relationship between phytoplankton population enhancement,the biological removal of nitrogen and phosphorus from the seawater,and the phytoplankton nitrogen an...

  1. Bivalve grazing can shape phytoplankton communities

    Science.gov (United States)

    Lucas, Lisa; Cloern, James E.; Thompson, Janet K.; Stacey, Mark T.; Koseff, Jeffrey K.

    2016-01-01

    The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.

  2. The annual cycles of phytoplankton biomass

    Science.gov (United States)

    Winder, M.; Cloern, J.E.

    2010-01-01

    Terrestrial plants are powerful climate sentinels because their annual cycles of growth, reproduction and senescence are finely tuned to the annual climate cycle having a period of one year. Consistency in the seasonal phasing of terrestrial plant activity provides a relatively low-noise background from which phenological shifts can be detected and attributed to climate change. Here, we ask whether phytoplankton biomass also fluctuates over a consistent annual cycle in lake, estuarine-coastal and ocean ecosystems and whether there is a characteristic phenology of phytoplankton as a consistent phase and amplitude of variability. We compiled 125 time series of phytoplankton biomass (chloro-phyll a concentration) from temperate and subtropical zones and used wavelet analysis to extract their dominant periods of variability and the recurrence strength at those periods. Fewer than half (48%) of the series had a dominant 12-month period of variability, commonly expressed as the canonical spring-bloom pattern. About 20 per cent had a dominant six-month period of variability, commonly expressed as the spring and autumn or winter and summer blooms of temperate lakes and oceans. These annual patterns varied in recurrence strength across sites, and did not persist over the full series duration at some sites. About a third of the series had no component of variability at either the six-or 12-month period, reflecting a series of irregular pulses of biomass. These findings show that there is high variability of annual phytoplankton cycles across ecosystems, and that climate-driven annual cycles can be obscured by other drivers of population variability, including human disturbance, aperiodic weather events and strong trophic coupling between phytoplankton and their consumers. Regulation of phytoplankton biomass by multiple processes operating at multiple time scales adds complexity to the challenge of detecting climate-driven trends in aquatic ecosystems where the noise to

  3. Association between product quality control and process quality control of bulk milk

    OpenAIRE

    Velthuis, A.; Asseldonk, van, M.M.L.

    2010-01-01

    Assessment of dairy-milk quality is based on product quality control (testing bulk-milk samples) and process quality control (auditing dairy farms). It is unknown whether process control improves product quality. To quantify possible association between product control and process control a statistical analysis was conducted. The analysis comprised 64.373 audit results on 26,953 dairy farms and all conducted lab tests of bulk-milk samples two, six or 12 months before the audit. Lab results in...

  4. Phosphate and iron limitation of phytoplankton biomass in Lake Tahoe

    Science.gov (United States)

    Chang, Cecily C.Y.; Kuwabara, J.S.; Pasilis, S.P.

    1992-01-01

    Bioassays were carried out to assess the response of inoculated, single-species diatom populations (Cyclotella meneghiniana and Aulocosiera italica) to additions of synthetic chelators and phosphate. A chemical speciation model along with the field data was also used to predict how trace metal speciation, and hence bioavailability, was affected by the chelator additions. Results suggest that phosphate was limiting to phytoplankton biomass. Other solutes, Fe in particular, may also exert controls on biomass. Nitrate limitation seems less likely, although Fe-limiting conditions may have led to an effective N limitation because algae require Fe to carry out nitrate reduction. -from Authors

  5. Planetary camera control improves microfiche production

    Science.gov (United States)

    Chesterton, W. L.; Lewis, E. B.

    1965-01-01

    Microfiche is prepared using an automatic control system for a planetary camera. The system provides blank end-of-row exposures and signals card completion so the legend of the next card may by photographed.

  6. Estimating phytoplankton photosynthesis by active fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Falkowski, P.G.; Kolber, Z.

    1992-01-01

    Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated in situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.

  7. Estimating phytoplankton photosynthesis by active fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Falkowski, P.G.; Kolber, Z.

    1992-10-01

    Photosynthesis can be described by target theory, At low photon flux densities, photosynthesis is a linear function of irradiance (I), The number of reaction centers (n), their effective absorption capture cross section {sigma}, and a quantum yield {phi}. As photosynthesis becomes increasingly light saturated, an increased fraction of reaction centers close. At light saturation the maximum photosynthetic rate is given as the product of the number of reaction centers (n) and their maximum electron transport rate (I/{tau}). Using active fluorometry it is possible to measure non-destructively and in real time the fraction of open or closed reaction centers under ambient irradiance conditions in situ, as well as {sigma} and {phi} {tau} can be readily, calculated from knowledge of the light saturation parameter, I{sub k} (which can be deduced by in situ by active fluorescence measurements) and {sigma}. We built a pump and probe fluorometer, which is interfaced with a CTD. The instrument measures the fluorescence yield of a weak probe flash preceding (f{sub 0}) and succeeding (f{sub 0}) a saturating pump flash. Profiles of the these fluorescence yields are used to derive the instantaneous rate of gross photosynthesis in natural phytoplankton communities without any incubation. Correlations with short-term simulated in situ radiocarbon measurements are extremely high. The average slope between photosynthesis derived from fluorescence and that measured by radiocarbon is 1.15 and corresponds to the average photosynthetic quotient. The intercept is about 15% of the maximum radiocarbon uptake and corresponds to the average net community respiration. Profiles of photosynthesis and sections showing the variability in its composite parameters reveal a significant effect of nutrient availability on biomass specific rates of photosynthesis in the ocean.

  8. Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean) : Iron biogeochemistry

    NARCIS (Netherlands)

    Gerringa, Loes J. A.; Alderkamp, Anne-Carlijn; Laan, Patrick; Thuroczy, Charles-Edouard; De Baar, Hein J. W.; Mills, Matthew M.; van Dijken, Gert L.; van Haren, Hans; Arrigo, Kevin R.

    2012-01-01

    Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive cont

  9. Distribution of phytoplankton pigments in Auranga, Ambika, Purna and Mindola estuaries of Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, B.N.; JiyalalRam, M.J.; Abidi, S.A.H.; Nair, V.R.

    m-3 respectively and the average concentration of carotenoids in the same order were 5.03, 7.32, 6.03 and 19.87 m-SPU m-3. Effect of pollution on phytoplankton production was discernible only at Mindola where the relatively higher level of nutrients...

  10. Phosphorus limitation during a phytoplankton spring bloom in the western Dutch Wadden Sea

    NARCIS (Netherlands)

    Ly, J.; Philippart, C.J.M.; Kromkamp, J.C.

    2014-01-01

    Like many aquatic ecosystems, the western Dutch Wadden Sea has undergone eutrophication. Due to changes in management policy, nutrient loads, especially phosphorus decreased after the mid-80s. It is still under debate, however, whether nutrients or light is limiting phytoplankton production in the w

  11. Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean) : Iron biogeochemistry

    NARCIS (Netherlands)

    Gerringa, Loes J. A.; Alderkamp, Anne-Carlijn; Laan, Patrick; Thuroczy, Charles-Edouard; De Baar, Hein J. W.; Mills, Matthew M.; van Dijken, Gert L.; van Haren, Hans; Arrigo, Kevin R.

    2012-01-01

    Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive

  12. Ocean acidification with (de)eutrophication will alter future phytoplankton growth and succession.

    Science.gov (United States)

    Flynn, Kevin J; Clark, Darren R; Mitra, Aditee; Fabian, Heiner; Hansen, Per J; Glibert, Patricia M; Wheeler, Glen L; Stoecker, Diane K; Blackford, Jerry C; Brownlee, Colin

    2015-04-07

    Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO2 into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake of dissolved inorganic carbon during photosynthesis increases water-column pH (bloom-induced basification). This increased pH can adversely affect plankton growth. With OA, basification commences at a lower pH. Using experimental analyses of the growth of three contrasting phytoplankton under different pH scenarios, coupled with mathematical models describing growth and death as functions of pH and nutrient status, we show how different conditions of pH modify the scope for competitive interactions between phytoplankton species. We then use the models previously configured against experimental data to explore how the commencement of bloom-induced basification at lower pH with OA, and operating against a background of changing patterns in nutrient loads, may modify phytoplankton growth and competition. We conclude that OA and changed nutrient supply into shelf seas with eutrophication or de-eutrophication (the latter owing to pollution control) has clear scope to alter phytoplankton succession, thus affecting future trophic dynamics and impacting both biogeochemical cycling and fisheries.

  13. Phytoplankton community dynamics in an intermittently open hypereutrophic coastal lagoon in southern Portugal

    Science.gov (United States)

    Coelho, Susana; Pérez-Ruzafa, Angel; Gamito, Sofia

    2015-12-01

    Phytoplankton community' dynamics were studied in Salgados coastal lagoon in order to evaluate the effects of excessive organic loads and also physical stress caused by the irregular opening of the lagoon. Salgados is a hypereutrophic intermittently open coastal lagoon, which received freshwater inputs from small rivers and from a wastewater treatment plant. Cyanophyceae dominated the phytoplankton communities most of the time; Bacillariophyceae became the main taxonomic group in winter when the lagoon was closed; Chlorophyceae was the major class in early summer; pico-nano flagellate algae accounted for a high percentage of total phytoplankton during spring. Potentially harmful taxa were observed during most of the sampling periods, forming blooms and accounting for a considerable percentage of total phytoplankton abundance. A strong differentiation among dry and wet seasons could be noticed. The dry season was dominated by Microsystis aeruginosa, Rhodomonas sp., pico-nano flagellate algae, Cyclotella spp. and Planktothrix sp., while the wet season, although still with the presence of Microsystis aeruginosa, was dominated by Dolichospermum spiroides. The best environmental variables explaining stations patterns and based on phytoplankton taxa were days of isolation, pH, and salinity. Temperature, cumulative rain and total phosphorus were also related with species and stations patterns. The high nutrient load in Salgados lagoon promoted the development and persistence of harmful algae blooms. Proper management of coastal lagoons involves not only the control of direct discharges of nutrients, but also of other factors, including water level and communication with the sea.

  14. Relationship between N : P : Si ratio and phytoplankton community composition in a tropical estuarine mangrove ecosystem

    Directory of Open Access Journals (Sweden)

    A. K. Choudhury

    2015-02-01

    Full Text Available The present work aims at understanding the importance of Brzezinski–Redfield ratio (modified Redfield ratio as a determinant of natural phytoplankton community composition in a mangrove ecosystem. Even though this ecoregion has been reported to be mostly eutrophic, localised and anthropogenic influences often result in habitat variability especially with regard to nutrient concentrations at different parts of this ecosystem. Phytoplankton, an important sentinel in aquatic ecosystems may respond differently to such alterations in habitat thereby bringing about significant changes in the community composition. Results show that even though habitat variability does exist at our study area and varied on a spatial and temporal scale, the nutrient concentrations were intricately balanced that never became limited and complemented well with the concept of modified Redfield ratio. However, an integrative approach to study phytoplankton community involving microscopy and rbcL clone library and sequencing approach revealed that it was the functional traits of individual phytoplankton taxa that determined the phytoplankton community composition rather than the nutrient concentrations of the study area. Hence we conclude that the recent concept of functional traits and elemental stoichiometry does not remain restricted to controlled environment of experimental studies only but occur in natural mangrove habitat.

  15. Relationship between N : P : Si ratio and phytoplankton community composition in a tropical estuarine mangrove ecosystem

    Science.gov (United States)

    Choudhury, A. K.; Bhadury, P.

    2015-02-01

    The present work aims at understanding the importance of Brzezinski-Redfield ratio (modified Redfield ratio) as a determinant of natural phytoplankton community composition in a mangrove ecosystem. Even though this ecoregion has been reported to be mostly eutrophic, localised and anthropogenic influences often result in habitat variability especially with regard to nutrient concentrations at different parts of this ecosystem. Phytoplankton, an important sentinel in aquatic ecosystems may respond differently to such alterations in habitat thereby bringing about significant changes in the community composition. Results show that even though habitat variability does exist at our study area and varied on a spatial and temporal scale, the nutrient concentrations were intricately balanced that never became limited and complemented well with the concept of modified Redfield ratio. However, an integrative approach to study phytoplankton community involving microscopy and rbcL clone library and sequencing approach revealed that it was the functional traits of individual phytoplankton taxa that determined the phytoplankton community composition rather than the nutrient concentrations of the study area. Hence we conclude that the recent concept of functional traits and elemental stoichiometry does not remain restricted to controlled environment of experimental studies only but occur in natural mangrove habitat.

  16. Environmental drivers of phytoplankton distribution and composition in Tagus Estuary, Portugal

    Science.gov (United States)

    Gameiro, C.; Cartaxana, P.; Brotas, V.

    2007-10-01

    A 7-year (March 1999-November 2005) monitoring program was developed in the Tagus estuary to study phytoplankton dynamics and several key controlling factors, namely nutrient content, light availability, atmospheric and hydrodynamic conditions (temperature, wind, rainfall, river flow, and salinity). Water was collected at four sampling sites on a monthly basis. Phytoplankton biomass, analyzed as Chl a, was moderate to low, when compared to other mesotidal estuaries: interannual average Chl a values ranged from 1.4 in winter to 8.0 μg L -1 in summer. A consistent seasonal pattern was observed, with a unimodal peak extending from late spring to summer. The phytoplankton community, as determined by biomarker pigment concentration using HPLC and CHEMTAX, was dominated by diatoms (57%), and included cryptophytes (23%), dinoflagellates (6.8%), chlorophytes (5.4%), euglenophytes (4.9%), and prasinophytes (2.6%). The method was capable of detecting phytoplankton taxa generally underestimated or overlooked when using standard microscopic techniques. Diatoms were the main bloom-formers in the summer Chl a maximum. A stepwise regression analysis showed that air temperature, river flow and irradiance explained 47% of the observed Chl a variance, illustrating the importance of climatic factors as driving forces for seasonal and interannual variability of phytoplankton.

  17. Nutrient and phytoplankton analysis of a Mediterranean coastal area.

    Science.gov (United States)

    Sebastiá, M T; Rodilla, M

    2013-01-01

    Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected (Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

  18. Nutrient and Phytoplankton Analysis of a Mediterranean Coastal Area

    Science.gov (United States)

    Sebastiá, M. T.; Rodilla, M.

    2013-01-01

    Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected ( Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

  19. Effects of mixing-induced irradiance fluctuations on nitrogen uptake in size-fractionated coastal phytoplankton communities

    Science.gov (United States)

    Maguer, Jean-François; L'Helguen, Stéphane; Waeles, Matthieu

    2015-03-01

    In coastal waters subjected to strong tidal forcing, phytoplankton populations are exposed to highly variable light regimes. To grow under such fluctuating light environments, phytoplankton adjust their physiological properties. Here, we investigated nitrogen (N) uptake patterns in the western English Channel to determine whether phytoplankton modify their physiological processes involved in N uptake in response to changing irradiance conditions induced by spring-neap tidal cycles. Nitrate (NO3-) and ammonium (NH4+) uptake kinetics as a function of irradiance (VN-E curves) were assessed using 15N tracer techniques on two size fractions (10 μm) of phytoplankton collected at 50% and 1% of surface irradiance during two spring-neap tidal cycles. Overall, the results showed that both small and large phytoplankton, whatever their vertical position in the water column, increased their maximum uptake capacity and their light utilization efficiency for the two N substrates following the decrease in vertical mixing intensity. Moreover, the improvement of irradiance conditions at neap tides was of greater benefit for the larger cells than for the smaller ones and was more favorable for NO3- uptake than for NH4+ uptake. These findings show that the light regime fluctuation resulting from the relaxation of tidal mixing during spring-neap tidal cycle leads to profound physiological adjustments of N uptake processes in phytoplankton communities. They suggest that the changes in NO3- uptake by large phytoplankton associated with the fortnightly spring-neap tidal cycle can account for most of the deviation in background productivity in the western English Channel which is based on NH4+ and is dominated by small cells. The dynamic light regime inherent to macrotidal coastal ecosystems could therefore determine, to a large extent, the importance of new vs. regenerated production as well as the size structure of the phytoplankton community.

  20. Developing an Integrated Set of Production Planning and Control Models

    OpenAIRE

    Wang, Hui

    2012-01-01

    This paper proposes an integrated set of production planning and control models that can be applied in the Push system (Make-to-stock). The integrated model include forecasting, aggregate planning, materials requirements planning, inventory control, capacity planning and scheduling. This integrated model solves the planning issues via three levels, which include strategic level, tactical level and operational level. The model obtains the optimal production plan for each product type in each p...

  1. Targeted metagenomics and ecology of globally important uncultured eukaryotic phytoplankton.

    Science.gov (United States)

    Cuvelier, Marie L; Allen, Andrew E; Monier, Adam; McCrow, John P; Messié, Monique; Tringe, Susannah G; Woyke, Tanja; Welsh, Rory M; Ishoey, Thomas; Lee, Jae-Hyeok; Binder, Brian J; DuPont, Chris L; Latasa, Mikel; Guigand, Cédric; Buck, Kurt R; Hilton, Jason; Thiagarajan, Mathangi; Caler, Elisabet; Read, Betsy; Lasken, Roger S; Chavez, Francisco P; Worden, Alexandra Z

    2010-08-17

    Among eukaryotes, four major phytoplankton lineages are responsible for marine photosynthesis; prymnesiophytes, alveolates, stramenopiles, and prasinophytes. Contributions by individual taxa, however, are not well known, and genomes have been analyzed from only the latter two lineages. Tiny "picoplanktonic" members of the prymnesiophyte lineage have long been inferred to be ecologically important but remain poorly characterized. Here, we examine pico-prymnesiophyte evolutionary history and ecology using cultivation-independent methods. 18S rRNA gene analysis showed pico-prymnesiophytes belonged to broadly distributed uncultivated taxa. Therefore, we used targeted metagenomics to analyze uncultured pico-prymnesiophytes sorted by flow cytometry from subtropical North Atlantic waters. The data reveal a composite nuclear-encoded gene repertoire with strong green-lineage affiliations, which contrasts with the evolutionary history indicated by the plastid genome. Measured pico-prymnesiophyte growth rates were rapid in this region, resulting in primary production contributions similar to the cyanobacterium Prochlorococcus. On average, pico-prymnesiophytes formed 25% of global picophytoplankton biomass, with differing contributions in five biogeographical provinces spanning tropical to subpolar systems. Elements likely contributing to success include high gene density and genes potentially involved in defense and nutrient uptake. Our findings have implications reaching beyond pico-prymnesiophytes, to the prasinophytes and stramenopiles. For example, prevalence of putative Ni-containing superoxide dismutases (SODs), instead of Fe-containing SODs, seems to be a common adaptation among eukaryotic phytoplankton for reducing Fe quotas in low-Fe modern oceans. Moreover, highly mosaic gene repertoires, although compositionally distinct for each major eukaryotic lineage, now seem to be an underlying facet of successful marine phytoplankton.

  2. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    Science.gov (United States)

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since

  3. Long Term Effect of Cyprinid Fishes on Phytoplankton and Zooplankton Communities in a Shallow Water Protection Reservoir

    Science.gov (United States)

    Mátyás, Kálmán; Korponai, János; Tátrai, István; Paulovits, Gábor

    2004-01-01

    The effects of fish kill and different fish stocks on the phytoplankton and zooplankton dynamics were studied in a shallow hypertrophic reservoir system. When fish stock was below 100 kg ha-1, nutrient availability was not the main limiting factor for growth of phytoplankton. Consequently top-down forces controlled phytoplankton. In the years with high fish stock (>100 kg ha-1) the bottom-up forces dominated as nutrient availability was the main limiting factor for growth of phytoplankton. We can conclude that significant water quality improvement can be achieved in the reservoir system by decreasing fish stock below 100 kg ha-1. Although clear-water phase could be stabilised temporary by macrophytes, stabilisation of good water quality requires continuous regulation of fish community. (

  4. Mid Pleistocene foraminiferal mass extinction coupled with phytoplankton evolution

    Science.gov (United States)

    Kender, Sev; McClymont, Erin L.; Elmore, Aurora C.; Emanuele, Dario; Leng, Melanie J.; Elderfield, Henry

    2016-06-01

    Understanding the interaction between climate and biotic evolution is crucial for deciphering the sensitivity of life. An enigmatic mass extinction occurred in the deep oceans during the Mid Pleistocene, with a loss of over 100 species (20%) of sea floor calcareous foraminifera. An evolutionarily conservative group, benthic foraminifera often comprise >50% of eukaryote biomass on the deep-ocean floor. Here we test extinction hypotheses (temperature, corrosiveness and productivity) in the Tasman Sea, using geochemistry and micropalaeontology, and find evidence from several globally distributed sites that the extinction was caused by a change in phytoplankton food source. Coccolithophore evolution may have enhanced the seasonal `bloom' nature of primary productivity and fundamentally shifted it towards a more intra-annually variable state at ~0.8 Ma. Our results highlight intra-annual variability as a potential new consideration for Mid Pleistocene global biogeochemical climate models, and imply that deep-sea biota may be sensitive to future changes in productivity.

  5. Spectral absorption coefficient of phytoplankton and its relation to chlorophyll a and remote sensing reflectance in coastal waters of southern China

    Institute of Scientific and Technical Information of China (English)

    CAO Wenxi; YANG Yuezhong; LIU Sheng; XU Xiaoqiang; YANG Dingtian; ZHANG Jianlin

    2005-01-01

    The spectral absorption coefficient of phytoplankton in coastal waters of southern China is investigated. Large variations in the absorption coefficient of phytoplankton are found. The absorption coefficient of phytoplankton at 443 nm ranged from 0. 006 m- 1 to 0. 484 m - 1, with an average value of 0. 067 m - 1. The chlorophyll-specific absorption coefficient of phytoplankton is also a bio-optical varito pigment composition of phytoplankton and package effect. The chlorophyll-specific absorption coefficient of phytoplankton decreases with the increasing of chlorophyll a concentration. This relationship can be described by a power law function, with the parameters and the coefficient of determination r2 as functions of wavelength, but the parameters describing the relationships in present study differed from that in Case 1 waters, thus the regional adjustment of model parameters was of particular significance for improving the accuracy of bio-optical algorithms for estimation of Chl-a concentration and primary production from remotely sensed data. Regression analysis of reflectance (R rs) ratio and absorption coefficient of phytoplankton (a ph) indicates a close correlation between them, which means that it is possible to retrieve absorption coefficient of phytoplankton using ocean color remote sensing data in optically complex coastal waters.

  6. Systematic Product Development of Control and Diagnosis Functionalities

    Science.gov (United States)

    Stetter, R.; Simundsson, A.

    2017-01-01

    In the scientific field of systematic product development a wide range of helpful methods, guidelines and tools were generated and published in recent years. Until now little special attention was given to design guidelines aiming at supporting product development engineers to design products that allow and support control or diagnosis functions. The general trend to ubiquitous computing and the first development steps towards cognitive systems as well as a general trend toward higher product safety, reliability and reduced total cost of ownership (TCO) in many engineering fields lead to a higher importance of control and diagnosis. In this paper a first attempt is made to formulate general valid guidelines how products can be developed in order to allow and to achieve effective and efficient control and diagnosis. The guidelines are elucidated on the example of an automated guided vehicle. One main concern of this paper is the integration of control and diagnosis functionalities into the development of complete systems which include mechanical, electrical and electronic subsystems. For the development of such systems the strategies, methods and tools of systematic product development have attracted significant attention during the last decades. Today, the functionality and safety of most products is to a large degree dependent on control and diagnosis functionalities. Still, there is comparatively little research concentrating on the integration of the development of these functionalities into the overall product development processes. The paper starts with a background describing Systematic Product Development. The second section deals with the product development of the sample product. The third part clarifies the notions monitoring, control and diagnosis. The following parts summarize some insights and formulate first hypotheses concerning control and diagnosis in Systematic Product Development.

  7. The dynamical landscape of marine phytoplankton diversity.

    Science.gov (United States)

    Lévy, Marina; Jahn, Oliver; Dutkiewicz, Stephanie; Follows, Michael J; d'Ovidio, Francesco

    2015-10-01

    Observations suggest that the landscape of marine phytoplankton assemblage might be strongly heterogeneous at the dynamical mesoscale and submesoscale (10-100 km, days to months), with potential consequences in terms of global diversity and carbon export. But these variations are not well documented as synoptic taxonomic data are difficult to acquire. Here, we examine how phytoplankton assemblage and diversity vary between mesoscale eddies and submesoscale fronts. We use a multi-phytoplankton numerical model embedded in a mesoscale flow representative of the North Atlantic. Our model results suggest that the mesoscale flow dynamically distorts the niches predefined by environmental contrasts at the basin scale and that the phytoplankton diversity landscape varies over temporal and spatial scales that are one order of magnitude smaller than those of the basin-scale environmental conditions. We find that any assemblage and any level of diversity can occur in eddies and fronts. However, on a statistical level, the results suggest a tendency for larger diversity and more fast-growing types at fronts, where nutrient supplies are larger and where populations of adjacent water masses are constantly brought into contact; and lower diversity in the core of eddies, where water masses are kept isolated long enough to enable competitive exclusion.

  8. Phytoplankton and sediments in Gulf of Mexico

    Science.gov (United States)

    2002-01-01

    Affected both by terrestrial factors like agriculture, deforestation, and erosion, and by marine factors like salinity levels, ocean temperature and water pollution, coastal environments are the dynamic interface between land and sea. In this MODIS image from January 15, 2002, the Gulf of Mexico is awash in a mixture of phytoplankton and sediment. Tan-colored sediment is flowing out into the Gulf from the Mississippi River, whose floodplain cuts a pale, wide swath to the right of center in the image, and also from numerous smaller rivers along the Louisiana coast (center). Mixing with the sediment are the multi-colored blue and green swirls that reveal the presence of large populations of marine plants called phytoplankton. Phytoplankton populations bloom and then fade, and these cycles affect fish and mammals-including humans-higher up the food chain. Certain phytoplankton are toxic to both fish and humans, and coastal health departments must monitor ecosystems carefully, often restricting fishing or harvesting of shellfish until the blooms have subsided.

  9. Phytoplankton and sediments in Gulf of Mexico

    Science.gov (United States)

    2002-01-01

    Affected both by terrestrial factors like agriculture, deforestation, and erosion, and by marine factors like salinity levels, ocean temperature and water pollution, coastal environments are the dynamic interface between land and sea. In this MODIS image from January 15, 2002, the Gulf of Mexico is awash in a mixture of phytoplankton and sediment. Tan-colored sediment is flowing out into the Gulf from the Mississippi River, whose floodplain cuts a pale, wide swath to the right of center in the image, and also from numerous smaller rivers along the Louisiana coast (center). Mixing with the sediment are the multi-colored blue and green swirls that reveal the presence of large populations of marine plants called phytoplankton. Phytoplankton populations bloom and then fade, and these cycles affect fish and mammals-including humans-higher up the food chain. Certain phytoplankton are toxic to both fish and humans, and coastal health departments must monitor ecosystems carefully, often restricting fishing or harvesting of shellfish until the blooms have subsided.

  10. Automation and control of off-planet oxygen production processes

    Science.gov (United States)

    Marner, W. J.; Suitor, J. W.; Schooley, L. S.; Cellier, F. E.

    1990-01-01

    This paper addresses several aspects of the automation and control of off-planet production processes. First, a general approach to process automation and control is discussed from the viewpoint of translating human process control procedures into automated procedures. Second, the control issues for the automation and control of off-planet oxygen processes are discussed. Sensors, instruments, and components are defined and discussed in the context of off-planet applications, and the need for 'smart' components is clearly established.

  11. The metabolic control of schistosome egg production

    Science.gov (United States)

    Pearce, Edward J.; Huang, Stanley Ching-Cheng

    2015-01-01

    Schistosomiasis is a Neglected Tropical Disease caused by infection with trematode parasites of the genus Schistosoma. Despite ongoing treatment programs, the prevalence of schistosomiasis has failed to decline and the disease remains a cause of severe morbidity in millions of people. Understanding the biology of egg production by schistosomes is critical since eggs allow transmission of the infection, and when trapped in host tissues induce the immune responses that are responsible for the pathologic changes that underlie disease development. Unusually among trematodes, adult schistosomes exhibit sexual dimorphism and display a fascinating codependency in that the female is dependent on the male to grow and sexually mature. Thus virgin females are developmentally stunted compared to females from mixed-sex infections and are unable to lay eggs. Moreover, fecund female schistosomes rapidly lose the ability to produce eggs when placed in tissue culture. Here we discuss the metabolic regulation of egg production in schistosomes, and in particular the critical role played by fatty acid oxidation in this process. PMID:25850569

  12. Physical and Combustion Characteristics of Briquettes Made from Water Hyacinth and Phytoplankton Scum as Binder

    Directory of Open Access Journals (Sweden)

    R. M. Davies

    2013-01-01

    Full Text Available The study investigated the potential of water hyacinths and phytoplankton scum, an aquatic weed, as binder for production of fuel briquettes. It also evaluated some physical and combustion characteristics. The water hyacinths were manually harvested, cleaned, sun-dried, and milled to particle sizes distribution ranging from <0.25 to 4.75 mm using hammer mill. The water hyacinth grinds and binder (phytoplankton scum at 10% (B1, 20% (B2, 30% (B3, 40% (B4, and 50% (B5 by weight of each feedstock were fed into a steel cylindrical die of dimension 14.3 cm height and 4.7 cm diameter and compressed by hydraulic press at pressure 20 MPa with dwell time of 45 seconds. Data were analysed using analysis of variance and descriptive statistics. Initial bulk density of uncompressed mixture of water hyacinth and phytoplankton scum at different binder levels varied between 113.86 ± 3.75 (B1 and 156.93 ± 4.82 kg/m3 (B5. Compressed and relaxed densities of water hyacinth briquettes at different binder proportions showed significant difference . Durability of the briquettes improved with increased binder proportion. Phytoplankton scum improved the mechanical handling characteristics of the briquettes. It could be concluded that production of water hyacinth briquettes is feasible, cheaper, and environmentally friendly and that they compete favourably with other agricultural products.

  13. Phytoplankton assemblages in a reservoir cascade of a large tropical - subtropical river (SE, Brazil

    Directory of Open Access Journals (Sweden)

    MG Nogueira

    Full Text Available The phytoplankton assemblages from eight reservoirs of the Paranapanema River were studied during two consecutive years. Chlorophyceae and Bacillaryophyceae dominated in richness. The observed high number of taxa, 234, reflects the extensive sampling programme and evidences the necessity of considering the whole hydrograph basin to assess the biodiversity status of inland water ecosystems. The dams had a negative effect on phytoplankton richness, with higher number of taxa associate to riverine (non-regulated stretches. The tributary rivers also exhibited high species richness, showing the importance of considering the lateral dimension, in addition to the longitudinal one, for aquatic biota inventories in large river basins/reservoirs. Richness and diversity were also positively influenced by the connectivity with lateral wetlands (macrophyte-dominated lakes due to the periphyton influence. The phytoplankton abundance/biomass was not influenced by higher water retention time. Higher values occurred in the middle basin stretches (river-passage reservoirs due to the increase in the trophic conditions. There was a positive correlation with phosphorus. Poorer light conditions in the cascade do not limit the phytoplankton biomass, with assemblages dominated by species tolerant to turbulent conditions and high mineral turbidity. Bacillariophyceae and Cryptophyceae dominated numerically. The first group (unicellular forms was prominent in the large and oligotrophic upstream reservoirs. The second was highly abundant in the river-passage (low retention time, and more eutrophic, reservoirs. Cyanophyceae growth is probably controlled by advection processes (wash-out effect. The zooplankton does not control the phytoplankton biomass and the diversity of both groups is positively associated in the cascade. The structure of the phytoplankton assemblages showed to be a good indicator of the operationally distinct reservoirs of the Paranapanema cascade and

  14. A New Mathematical Modeling Technique for Pull Production Control Systems

    Directory of Open Access Journals (Sweden)

    O. Srikanth

    2013-12-01

    Full Text Available The Kanban Control System widely used to control the release of parts of multistage manufacturing system operating under a pull production control system. Most of the work on Kanban Control System deals with multi-product manufacturing system. In this paper, we are proposing a regression modeling technique in a multistage manufacturing system is to be coordinates the release of parts into each stage of the system with the arrival of customer demands for final products. And also comparing two variants stages of the Kanban Control System model and combines with mathematical and Simulink model for the production coordination of parts in an assembly manufacturing systems. In both variants, the production of a new subassembly is authorized only when an assembly Kanban is available. Assembly kanbans become available when finished product is consumed. A simulation environment for the product line system has to generate with the proposed model and the mathematical model have to give implementation against the simulation model in the working platform of MATLAB. Both the simulation and model outputs have provided an in depth analysis of each of the resulting control system for offering model of a product line system.

  15. Controlling nitrous oxide emissions from grassland livestock production systems

    NARCIS (Netherlands)

    Oenema, O.; Gebauer, G.; Rodriguez, M.; Sapek, A.; Jarvis, S.C.; Corré, W.J.; Yamulki, S.

    1998-01-01

    There is growing awareness that grassland livestock production systems are major sources of nitrous oxide (N2O). Controlling these emissions requires a thorough understanding of all sources and controlling factors at the farm level. This paper examines the various controlling factors and proposes

  16. STATISTICAL CONTROL OF PROCESSES AND PRODUCTS IN AGRICULTURE

    Directory of Open Access Journals (Sweden)

    D. Horvat

    2006-06-01

    Full Text Available Fundamental concept of statistical process control is based on decision-making about the process on the basis of comparison of data collected from process with calculated control limits. Statistical process and quality control of agricultural products is used to provide agricultural products that will satisfy customer requirements in a view of quality pretension as well as costumer requirements in a cost price. In accordance with ISO 9000, quality standards for process and products are defined. There are many institutions in Croatia that work in accordance with these standards. Implementation of statistical process control and usage of a control charts can greatly help in convergence to the standards and in decreasing of production costs. To illustrate the above mentioned we tested a work quality of a nozzle at the eighteen meter clutch sprayer.

  17. Remote sensing of bacterial response to degrading phytoplankton in the Arabian Sea.

    Science.gov (United States)

    Priyaja, P; Dwivedi, R; Sini, S; Hatha, M; Saravanane, N; Sudhakar, M

    2016-12-01

    A remote sensing technique has been developed to detect physiological condition of phytoplankton using in situ and moderate imaging spectroradiometer (MODIS)-Aqua data. The recurring massive mixed algal bloom of diatom and Noctiluca scintillans in the Northern Arabian Sea during winter-spring was used as test bed to study formation, growth and degradation of phytoplankton. The ratio of chlorophyll (chl) to particulate organic carbon (POC) was considered as an indicator of phytoplankton physiological condition and used for the approach development. Algal blooms represent the areas of new production, and therefore, knowledge of their degradation is important to the study microbial loop and export carbon flux. Relation of chl/POC ratio with bacterial abundance revealed Gaussian distribution. Bacteria were strongly correlated with POC, and hence, the latter which is available from satellite data could be used as a proxy for remote assessment of bacteria. Thresholds for active and degrading phytoplankton were determined using the ratio computed from the satellite data. The criteria were implemented on MODIS data to generate an image representing distribution of degrading algal bloom. Bacteria abundance data from two validation cruises during dinoflagellate and cyanobacteria bloom confirmed well match up of phytoplankton degradation information from the satellite. Comparison of environmental parameters during decay phase of dinoflagellate (N. scintillans bloom (winter) and Trichodesmium bloom (summer) revealed that degradation after active Trichodesmium bloom was more severe as compared to the N. scintillans. The present study also highlights the prediction capability of phytoplankton degradation using a time series of satellite retrieved chlorophyll/POC images.

  18. Evaluating the Addition of a Dinoflagellate Phytoplankton Functional Type Using Radiance Anomalies for Monterey Bay, CA

    Science.gov (United States)

    Houskeeper, H. F.; Kudela, R. M.

    2016-12-01

    Ocean color sensors have enabled daily, global monitoring of phytoplankton productivity in the world's oceans. However, to observe key structures such as food webs, or to identify regime shifts of dominant species, tools capable of distinguishing between phytoplankton functional types using satellite remote sensing reflectance are necessary. One such tool developed by Alvain et al. (2005), PHYSAT, successfully linked four phytoplankton functional types to chlorophyll-normalized remote sensing spectra, or radiance anomalies, in case-1 waters. Yet this tool was unable to characterize dinoflagellates because of their ubiquitous background presence in the open ocean. We employ a radiance anomaly technique based on PHYSAT to target phytoplankton functional types in Monterey Bay, a region where dinoflagellate populations are larger and more variable than in open ocean waters, and thus where they may be viable targets for satellite remote sensing characterization. We compare with an existing Santa Cruz Wharf photo-pigment time series spanning from 2006 to the present to regionally ground-truth the method's predictions, and we assess its accuracy in characterizing dinoflagellates, a phytoplankton group that impacts the region's fish stocks and water quality. For example, an increase in dinoflagellate abundance beginning in 2005 led to declines in commercially important fish stocks that persisted throughout the following year. Certain species of dinoflagellates in Monterey Bay are also responsible for some of the harmful algal bloom events that negatively impact the shellfish industry. Moving toward better tools to characterize phytoplankton blooms is important for understanding ecosystem shifts, as well as protecting human health in the surrounding areas.

  19. The Effects of Bis(tri-n-butyltin) Oxide on Three Species of Marine Phytoplankton.

    Science.gov (United States)

    1985-05-01

    fluorescence with time indicates an actively photosynthesizing culture that is healthy and growing. The photosynthetic capability of phytoplankton was...vivo fluorescence data with the FRs suggests that the control replicates were actively photosynthesizing and growing. For each species, the mean in vivo

  20. Warming accelerates termination of a phytoplankton spring bloom by fungal parasites

    NARCIS (Netherlands)

    Frenken, Thijs; Velthuis, Mandy; Senerpont Domis, de L.N.; Stephan, Susanne; Aben, Ralf; Kosten, Sarian; Donk, van Ellen; Waal, Van de D.B.

    2016-01-01

    Climate change is expected to favour infectious diseases across ecosystems worldwide. In freshwater and marine environments, parasites play a crucial role in controlling plankton population dynamics. Infection of phytoplankton populations will cause a transfer of carbon and nutrients into parasit

  1. Engineering Documentation Control Handbook Configuration Management and Product Lifecycle Management

    CERN Document Server

    Watts, Frank B

    2011-01-01

    In this new edition of his widely-used Handbook, Frank Watts, widely recognized for his significant contributions to engineering change control processes, provides a thoroughly practical guide to the implementation and improvement of Engineering Documentation Control (EDC), Product Lifecycle Management and Product Configuration Management (CM). Successful and error-free implementation of EDC/CM is critical to world-class manufacturing. Huge amounts of time are wasted in most product manufacturing environments over EDC/CM issues such as interchangeability, document release and change control -

  2. Spatio-temporal variability of phytoplankton dimensional classes in the Mediterranean Sea from satellite data

    Science.gov (United States)

    Sammartino, Michela; Di Cicco, Annalisa; Marullo, Salvatore; Santoleri, Rosalia

    2016-04-01

    Phytoplankton contributes to fix half of the carbon dioxide released on Earth, becoming a key component not only in the carbon cycle, but also in several biogeochemical cycles. It is involved in the control of greenhouse gases and, consequently, in the effect of climate change on marine system. Therefore, phytoplankton is often considered one of the most common bio-indicator for any environmental changes, which, in turn, can affect the algal community composition and structure. The alteration of the biological, physical and chemical conditions in the ocean can be reflected in the algal assemblage structure, in terms of variation of dominant size class and taxonomic composition. In this work, the seasonal and year-to-year variability of the phytoplankton size class (PSC) spatial distribution has been examined in the Mediterranean Sea using ten year of satellite observations. The estimation of PSCs from space is based on relationship between chlorophyll a (Chl a) and diagnostic pigments that should be verified at regional scales. Our analysis shows that the Mediterranean pigments ratios differs from the global ones; therefore, we regionalized the mathematical relation existing between the Chl a and the diagnostic pigments, used in the in situ PSC identification. This regionally tuned relation allowed to improve the estimation of PSCs from space by reducing the observed bias between modelled and measured PSCs. The analysis of PSC satellite time series allowed, for the first time, to have a quantitative description of the seasonal and inter-annual variability of the spatial distribution of the algal community in the Mediterranean Sea. The results demonstrated that the pico-phytoplankton contributes with high values to the total Chl a, especially in summer and in ultra-oligotrophic environments, such as the Levantine basin. Micro-phytoplankton contribution results high during spring bloom period in offshore areas, characterized by a strong water mixing; while, in

  3. Seasonal phytoplankton blooms in the Gulf of Aden revealed by remote sensing

    KAUST Repository

    Gittings, John A.

    2016-11-25

    The Gulf of Aden, situated in the northwest Arabian Sea and linked to the Red Sea, is a relatively unexplored ecosystem. Understanding of large-scale biological dynamics is limited by the lack of adequate datasets. In this study, we analyse 15 years of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass) acquired from the Ocean Colour Climate Change Initiative (OC-CCI) of the European Space Agency (ESA). The improved spatial coverage of OC-CCI data in the Gulf of Aden allows, for the first time, an investigation into the full seasonal succession of phytoplankton biomass. Analysis of indices of phytoplankton phenology (bloom timing) reveals distinct phytoplankton growth periods in different parts of the gulf: a large peak during August (mid-summer) in the western part of the gulf, and a smaller peak during November (mid-autumn) in the lower central gulf and along the southern coastline. The summer bloom develops rapidly at the beginning of July, and its peak is approximately three times higher than that of the autumnal bloom. Remotely-sensed sea-surface temperature (SST), wind-stress curl, vertical nutrient profiles and geostrophic currents inferred from the sea-level anomaly, were analysed to examine the underlying physical mechanisms that control phytoplankton growth. During summer, the prevailing southwesterlies cause upwelling along the northern coastline of the gulf (Yemen), leading to an increase in nutrient availability and enhancing phytoplankton growth along the coastline and in the western part of the gulf. In contrast, in the central region of the gulf, lowest concentrations of Chl-a are observed during summer, due to strong downwelling caused by a mesoscale anticyclonic eddy. During autumn, the prevailing northeasterlies enable upwelling along the southern coastline (Somalia) causing local nutrient enrichment in the euphotic zone, leading to higher levels of phytoplankton biomass along the coastline and in the lower central gulf

  4. Intracellular speciation and transformation of inorganic mercury in marine phytoplankton.

    Science.gov (United States)

    Wu, Yun; Wang, Wen-Xiong

    2014-03-01

    Metal speciation is closely related to toxicity in aquatic organisms, but quantitative study of mercury transformation has rarely been reported. In this study, the ability of three marine phytoplankton species, including a green alga Chlorella autotrophica, a flagellate Isochrysis galbana and a diatom Thalassiosira weissflogii, to convert inorganic mercury were examined. We found that all algae tested were able to transform Hg(II) into dissolved gaseous mercury (DGM), phytochelatin (PC) complexes and metacinnabar (β-HgS). The most tolerant species, T. weissflogii, generally produced the highest level of PCs and β-HgS. Attributed to the highest DGM production ability, C. autotrophica accumulated the least Hg, but was the most sensitive due to low PC induction and β-HgS formation. Of the added Hg(II), less than 5% was reduced to DGM per day in all species. Of the intracellular Hg, <20% and 20-90% were chelated by PCs and transformed into β-HgS, respectively. These results suggest that intracellular biotransformation might be more important than bioavailability regulation in Hg(II) detoxification in marine phytoplankton.

  5. IMPLEMENTATION OF CONTROL CARDS AND SUPPORTING METHOD IN PRODUCTION ENGINEERING

    Directory of Open Access Journals (Sweden)

    Anna WOLNOWSKA

    2012-10-01

    Full Text Available In the article there were presented chosen method associated with statistical control of production processes. Mainly focused on control cards and Pareto‐Lorenz analysis. Showed method were implemented to analysis production process stability of hearing aids in X company (the brand name don’t give because date of production is secret. Researches were made few months after new assembly lines starts‐up. Main aim of researches was defects types identification occurred in production process and determine the scale of effect. Finally received results were satisfactory, i.e. despite of occurred errors, control cards analysis showed that production process of BTE‐type (Behind‐The‐Ear hearing aids was stable.

  6. Optimum Production Control and Workforce Scheduling of Machining Project

    Science.gov (United States)

    Lan, Tian-Syung; Lo, Chih-Yao; Hou, Cheng-I.

    Through the proposed model in this study, the production control with the consideration of workforce scheduling for advanced manufacturing systems becomes realistically and concretely solvable. This study not only meditates the concept of balancing machine productivity and human ability into the objective, but also implements Calculus of Variations to optimize the profit for a deterministic production quantity. In addition, the optimum solutions of dynamic productivity control and workforce scheduling are comprehensively provided. Moreover, the decision criteria for selecting the optimum solution and the sensitivity analysis of the critical variables are fully discussed. This study definitely contributes the applicable strategy to control the productivity and workforce in manufacturing and provides the valuable tool to conclusively optimize the profit of a machining project for operations research in today`s manufacturing industry with profound insight.

  7. Role of phytoplankton in maintaining endemicity and seasonality of cholera in Bangladesh.

    Science.gov (United States)

    Islam, M Sirajul; Islam, M Shafiqul; Mahmud, Zahid H; Cairncross, Sandy; Clemens, John D; Collins, Andrew E

    2015-09-01

    In Bangladesh, cholera is endemic and maintains a regular seasonal pattern. The role of phytoplankton in maintaining endemicity and seasonality of cholera was monitored in Matlab, Bangladesh. Phytoplankton and water samples were collected from two ponds bi-weekly for 1 year. The association of Vibrio cholerae O1 with phytoplankton was studied by culture and direct fluorescent antibody techniques. The bio-physicochemical parameters of water were measured and data for cases of cholera were collected from the records of Matlab hospital. The correlation of cholera cases with levels of phytoplankton, V. cholerae and bio-physicochemical parameters of water was carried out using Pearson's correlation coefficients. V. cholerae O1 survived for 48 days in association with Anabaena variabilis in a culturable state, but survived for a year in a viable but non-culturable (VBNC) state. V. cholerae survived for 12 and 32 days in a culturable state in control water (without algae) and water with algae, respectively. There was a significant correlation between changing levels of cholera cases in the community and the blue green algae and total phytoplankton in the aquatic environment. A significant correlation was also found between the cholera cases and chlorophyll-a and VBNC V. cholerae O1 in the aquatic environment. This study demonstrated the role of phytoplankton in maintaining endemicity and seasonality of cholera in Bangladesh. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay)

    KAUST Repository

    Álvarez, E

    2015-12-09

    © Inter-Research 2016. Shelf waters of the Cantabrian Sea (southern Bay of Biscay) are productive ecosystems with a marked seasonality. We present the results from 1 yr of monthly monitoring of the phytoplankton community together with an intensive sampling carried out in 2 contrasting scenarios during the summer and autumn in a mid-shelf area. Stratification was apparent on the shelf in summer, while the water column was comparatively well mixed in autumn. The size structure of the photoautotrophic community, from pico-to micro-phytoplankton, was tightly coupled with the meteo-climatic and hydrographical conditions. Over the short term, variations in the size structure and chlorophyll content of phytoplankton cells were related to changes in the physico-chemical environment, through changes in the availability of nutrients and light. Uncoupling between the dynamics of carbon biomass and chlorophyll resulted in chlorophyll to carbon ratios dependent on body size. The slope of the size dependence of chlorophyll content increased with increasing irradiance, reflecting different photoacclimation plasticity from pico-to micro-phytoplankton. The results have important implications for the productivity and the fate of biogenic carbon in this region, since the size dependence of photosynthetic rates is directly related to the size scaling of chlorophyll content.

  9. Phytoplankton succession in an isolated upwelled Benguela water body in relation to different initial nutrient conditions

    Science.gov (United States)

    Wasmund, Norbert; Nausch, Günther; Hansen, Anja

    2014-11-01

    Freshly upwelled water is poor in phytoplankton biomass but rich in nutrients. With its ageing, phytoplankton biomass increases whereas the nutrients are consumed. The overall aim of our investigation was to check the succession in the phytoplankton composition as a consequence of changing nutrient conditions. The experiments were carried out in mesocosms filled with surface water in the northern Benguela region and installed on board of R/V "Maria S. Merian". In the freshly upwelled water, phytoplankton took up nitrogen at a higher rate than phosphorus if compared with the Redfield ratio. Therefore, nitrogen was exhausted already by day 6. Nitrogen limitation after day 6 was indicated by decreasing chlorophyll a (chla) concentrations, primary production rates and productivity indices and increasing C/N ratios in particulate matter. Despite nitrogen limitation, phosphorus addition stimulated further growth, mainly of diatoms, pointing to luxury uptake. Cyanobacteria did not develop and nitrogen fixation was zero even with phosphorus and iron addition. Diatoms stay the most important group in the freshly upwelled water, but autotrophic and heterotrophic dinoflagellates increase strongly in the matured upwelled water. Mesocosms excluded disturbances by advective water transports, which influence the study of succssions under field conditions.

  10. An Inverse Modeling Approach to Estimating Phytoplankton Pigment Concentrations from Phytoplankton Absorption Spectra

    Science.gov (United States)

    Moisan, John R.; Moisan, Tiffany A. H.; Linkswiler, Matthew A.

    2011-01-01

    Phytoplankton absorption spectra and High-Performance Liquid Chromatography (HPLC) pigment observations from the Eastern U.S. and global observations from NASA's SeaBASS archive are used in a linear inverse calculation to extract pigment-specific absorption spectra. Using these pigment-specific absorption spectra to reconstruct the phytoplankton absorption spectra results in high correlations at all visible wavelengths (r(sup 2) from 0.83 to 0.98), and linear regressions (slopes ranging from 0.8 to 1.1). Higher correlations (r(sup 2) from 0.75 to 1.00) are obtained in the visible portion of the spectra when the total phytoplankton absorption spectra are unpackaged by multiplying the entire spectra by a factor that sets the total absorption at 675 nm to that expected from absorption spectra reconstruction using measured pigment concentrations and laboratory-derived pigment-specific absorption spectra. The derived pigment-specific absorption spectra were further used with the total phytoplankton absorption spectra in a second linear inverse calculation to estimate the various phytoplankton HPLC pigments. A comparison between the estimated and measured pigment concentrations for the 18 pigment fields showed good correlations (r(sup 2) greater than 0.5) for 7 pigments and very good correlations (r(sup 2) greater than 0.7) for chlorophyll a and fucoxanthin. Higher correlations result when the analysis is carried out at more local geographic scales. The ability to estimate phytoplankton pigments using pigment-specific absorption spectra is critical for using hyperspectral inverse models to retrieve phytoplankton pigment concentrations and other Inherent Optical Properties (IOPs) from passive remote sensing observations.

  11. Managing unforeseen events in production scheduling and control

    DEFF Research Database (Denmark)

    Arica, E.; Falster, Peter; Hvolby, H. H.

    2016-01-01

    The production planning and control process is performed within complex and dynamic organizations made up of customer expectations, equipment, materials, people, information, and technologies. Changes in both internal and external factors can create a variety of unforeseen events, which make...

  12. Suprachiasmatic Nucleus Neuropeptides and Their Control of Endogenous Glucose Production

    NARCIS (Netherlands)

    Foppen, E; Tan, A A T; Ackermans, M T; Fliers, E; Kalsbeek, A

    2016-01-01

    Defective control of endogenous glucose production is an important factor responsible for hyperglycaemia in the diabetic individual. During the past decade, progressively more evidence has appeared indicating a strong and potentially causal relationship between disturbances of the circadian system a

  13. Advancement in modern approaches to mineral production quality control

    Science.gov (United States)

    Freidina, EV; Botvinnik, AA; Dvornikova, AN

    2017-02-01

    The natural resource potential of mineral deposits is represented by three categories: upside, attainable and investment. A modern methodology is proposed in this paper for production quality control, and its tools aimed at ensuring agreement between the product quality and the market requirements are described. The definitions of the costs of the product quality compliance and incompliance with the consumer requirements are introduced; the latter is suggested to use in evaluating resource potential of mineral deposits at a certain degree of probability.

  14. Virtual Factory Framework for Supporting Production Planning and Control.

    Science.gov (United States)

    Kibira, Deogratias; Shao, Guodong

    2017-01-01

    Developing optimal production plans for smart manufacturing systems is challenging because shop floor events change dynamically. A virtual factory incorporating engineering tools, simulation, and optimization generates and communicates performance data to guide wise decision making for different control levels. This paper describes such a platform specifically for production planning. We also discuss verification and validation of the constituent models. A case study of a machine shop is used to demonstrate data generation for production planning in a virtual factory.

  15. Supervisory controller synthesis for product lines using CIF 3

    NARCIS (Netherlands)

    M.H. ter Beek (Maurice); M.A. Reniers (Michel); E.P. de Vink (Erik Peter)

    2016-01-01

    textabstractUsing the CIF 3 toolset, we illustrate the general idea of controller synthesis for product line engineering for a prototypical example of a family of coffee machines. The challenge is to integrate a number of given components into a family of products such that the resulting behaviour

  16. Dubai to take control of its oil production

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2006-09-15

    The government of Dubai is to take control of the emirate's oil production. From 2nd April, 2007, the foreign consortium responsible for nearly all of Dubai's production will cease to operate the concession and be replaced by a new state-owned company, bringing to an end an era that has lasted over forty years. (author)

  17. Designing pull production control systems : Customization and robustness

    NARCIS (Netherlands)

    Gaury, E.G.A.

    2000-01-01

    In this dissertation we address the issues of selecting and configuring pull production control systems for single-product flowlines. We start with a review of pull systems in the literature, yielding a new classification. Then we propose a novel selection procedure based on a generic system that we

  18. Regional to Global Assessments of Phytoplankton Dynamics From The SeaWiFS Mission

    Science.gov (United States)

    Siegel, David; Behrenfeld, Michael; Maritorena, Stephanie; McClain, Charles R.; Antoine, David; Bailey, Sean W.; Bontempi, Paula S.; Boss, Emmanuel S.; Dierssen, Heidi M.; Doney, Scott C.; Eplee, R. E., Jr.; Evans, Robert H.; Feldman, Gene C.; Fields, Erik; Franz, Bryan A.; Kuring, Norman A.; Mengelt, Claudia; Nelson, Norman B.; Patt, Fred S.; Robinson, Wayne D.; Sarmiento, J. L.; Swan, C. M.; Werdell, Paul J.; Westberry, T. K.; Wilding, John G.; Yoder, J. A.

    2013-01-01

    Photosynthetic production of organic matter by microscopic oceanic phytoplankton fuels ocean ecosystems and contributes roughly half of the Earth's net primary production. For 13 years, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission provided the first consistent, synoptic observations of global ocean ecosystems. Changes in the surface chlorophyll concentration, the primary biological property retrieved from SeaWiFS, have traditionally been used as a metric for phytoplankton abundance and its distribution largely reflects patterns in vertical nutrient transport. On regional to global scales, chlorophyll concentrations covary with sea surface temperature (SST) because SST changes reflect light and nutrient conditions. However, the oceanmay be too complex to be well characterized using a single index such as the chlorophyll concentration. A semi-analytical bio-optical algorithm is used to help interpret regional to global SeaWiFS chlorophyll observations from using three independent, well-validated ocean color data products; the chlorophyll a concentration, absorption by CDM and particulate backscattering. First, we show that observed long-term, global-scale trends in standard chlorophyll retrievals are likely compromised by coincident changes in CDM. Second, we partition the chlorophyll signal into a component due to phytoplankton biomass changes and a component caused by physiological adjustments in intracellular chlorophyll concentrations to changes in mixed layer light levels. We show that biomass changes dominate chlorophyll signals for the high latitude seas and where persistent vertical upwelling is known to occur, while physiological processes dominate chlorophyll variability over much of the tropical and subtropical oceans. The SeaWiFS data set demonstrates complexity in the interpretation of changes in regional to global phytoplankton distributions and illustrates limitations for the assessment of phytoplankton dynamics using chlorophyll

  19. Effect of high iron concentration enrichment on the phytoplankton in the Prydz Bay

    Institute of Scientific and Technical Information of China (English)

    张武昌; 孙松; 张永山; 扈传昱; 刘诚刚

    2004-01-01

    Shipboard iron enrichment phytoplankton incubations were carried out in the Prydz Bay, Antarctic, in January through to March 2002. Waters for the three incubations ( Exp 1,2 and 3 ) were collected from 20 m depth in three stations ( St. Ⅰ -1, Ⅶ-1 and Ⅶ-5 ), respectively. Although the nutrient concentrations in the surface waters of the three stations were consistently high, the Chl a concentrations varied considerably. Chl a concentrations in the 20 m depth of St. Ⅰ-1 and Ⅶ-1 werewas 2.35-2.65 for St. Ⅶ-5. There were six levels of enriched iron concentrations(control 5, 10, 20, 40 and 80 nM) in Exp 1 (6-29th, January) while three enriched iron levels (control 10 and 40 nM) were arranged in Exp 2 and 3 (both were from 20th February to 4 th March). The iron enrichments stimulated the phytoplankton growth and nutrient drawdown in Exp 1 and Exp 2. In Exp 3, phytoplankton growth and nutrient drawdown were at nearly the same rate in the control and iron enriched bottles. In Exp 1, Chl a concentrations in the bottles with 20, 40 and 80 nM iday, respectively, with a growth rate of 0.36-0.38 d-1. Chl a concentration in the day ( growth rate 0.27 d - 1 ). Phytoplankton growth rates in the control bottle and the bottle enriched with 5 nM iron were 0.13 and 0.16 d -1, respectively. In Exp 2, the Chl a growth rates were 0.13, 0.32 and 0.40 d-1 in the control bottle and bottles with 10 and 40 nM iron enrichments, respectively. It seems that 10 nM iron enrichment was not enough to stimulate the phytoplankton to reach their maximum growth rate. The result that the phytoplankton < 10 μm bloomed in Exp 1 and 2 was controversial to the "Ecumenical Iron Hypothesis" of Morel et al. ( 1991 ) that upon enrichment of iron, phytoplankton >10 μm would grow faster than phytoplankton<10 μm.

  20. In situ Measurements of Phytoplankton Fluorescence Using Low Cost Electronics

    Directory of Open Access Journals (Sweden)

    Dana L. Wright

    2013-06-01

    Full Text Available Chlorophyll a fluorometry has long been used as a method to study phytoplankton in the ocean. In situ fluorometry is used frequently in oceanography to provide depth-resolved estimates of phytoplankton biomass. However, the high price of commercially manufactured in situ fluorometers has made them unavailable to some individuals and institutions. Presented here is an investigation into building an in situ fluorometer using low cost electronics. The goal was to construct an easily reproducible in situ fluorometer from simple and widely available electronic components. The simplicity and modest cost of the sensor makes it valuable to students and professionals alike. Open source sharing of architecture and software will allow students to reconstruct and customize the sensor on a small budget. Research applications that require numerous in situ fluorometers or expendable fluorometers can also benefit from this study. The sensor costs US$150.00 and can be constructed with little to no previous experience. The sensor uses a blue LED to excite chlorophyll a and measures fluorescence using a silicon photodiode. The sensor is controlled by an Arduino microcontroller that also serves as a data logger.

  1. Phytoplankton phenology indices in coral reef ecosystems: Application to ocean-color observations in the Red Sea

    KAUST Repository

    Racault, Marie-Fanny

    2015-02-18

    Phytoplankton, at the base of the marine food web, represent a fundamental food source in coral reef ecosystems. The timing (phenology) and magnitude of the phytoplankton biomass are major determinants of trophic interactions. The Red Sea is one of the warmest and most saline basins in the world, characterized by an arid tropical climate regulated by the monsoon. These extreme conditions are particularly challenging for marine life. Phytoplankton phenological indices provide objective and quantitative metrics to characterize phytoplankton seasonality. The indices i.e. timings of initiation, peak, termination and duration are estimated here using 15 years (1997–2012) of remote sensing ocean-color data from the European Space Agency (ESA) Climate Change Initiative project (OC-CCI) in the entire Red Sea basin. The OC-CCI product, comprising merged and bias-corrected observations from three independent ocean-color sensors (SeaWiFS, MODIS and MERIS), and processed using the POLYMER algorithm (MERIS period), shows a significant increase in chlorophyll data coverage, especially in the southern Red Sea during the months of summer NW monsoon. In open and reef-bound coastal waters, the performance of OC-CCI chlorophyll data is shown to be comparable with the performance of other standard chlorophyll products for the global oceans. These features have permitted us to investigate phytoplankton phenology in the entire Red Sea basin, and during both winter SE monsoon and summer NW monsoon periods. The phenological indices are estimated in the four open water provinces of the basin, and further examined at six coral reef complexes of particular socio-economic importance in the Red Sea, including Siyal Islands, Sharm El Sheikh, Al Wajh bank, Thuwal reefs, Al Lith reefs and Farasan Islands. Most of the open and deeper waters of the basin show an apparent higher chlorophyll concentration and longer duration of phytoplankton growth during the winter period (relative to the summer

  2. Variation of summer phytoplankton community composition and its relationship to nitrate and regenerated nitrogen assimilation across the North Atlantic Ocean

    Science.gov (United States)

    Van Oostende, N.; Fawcett, S. E.; Marconi, D.; Lueders-Dumont, J.; Sabadel, A. J. M.; Woodward, E. M. S.; Jönsson, B. F.; Sigman, D. M.; Ward, B. B.

    2017-03-01

    The North Atlantic Ocean is considered a nitrogen (N) limited system once vernal stabilisation of the water column alleviates light limitation and allows phytoplankton growth to deplete surface nutrients to virtually undetectable levels. Ammonium and other regenerated N forms are then the main surface N source for phytoplankton production. The effort to determine which phytoplankton groups contribute to long-term biological export production would be greatly aided by information on which phytoplankton groups are responsible for the assimilation of nitrate, as opposed to those assimilating predominantly regenerated N. In this study, we used the natural abundance N isotopes to examine basin-scale patterns of nitrate and regenerated N assimilation and evaluated the relationships between these trends and phytoplankton community composition. Samples were collected during a summertime cruise transect (August-September 2013) from the subtropical (36°N 73°W) to the subarctic (54°N 20°W) North Atlantic and analysed for the N isotopic composition (δ15N vs. N2 in air) of particulate nitrogen (PN) and nitrate, size-fractionated chlorophyll a, and phytoplankton group biomass using flow cytometry. The depth of the 300 nmol l-1 nitrate isopleth shoaled from the subtropics (79 m), where phytoplankton stripped surface waters of nitrate, to the subarctic, where it intersected with the surface and the upward nutrient supply drove a summer phytoplankton bloom. The δ15N of PN above the nitracline increased from the subtropics (-0.3‰) to the subarctic (4.2‰), reflecting both a change in the δ15N of the subsurface nitrate source (from 2.4‰ to 5.1‰) and increased reliance by phytoplankton on nitrate relative to regenerated N. Throughout the transect, the phytoplankton community was mainly composed of pico- and nano-sized cells (>88% of chlorophyll a in the <20 μm size fraction). In the part of the transect southwest of the Grand Banks, Prochlorococcus and Synechococcus

  3. Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton-bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes

    Science.gov (United States)

    Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villafañe, V. E.; Helbling, E. W.

    2015-02-01

    An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280-400 nm) and photosynthetically active radiation (PAR, 400-700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton-bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton-bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.

  4. Patterns and multi-scale drivers of phytoplankton species richness in temperate peri-urban lakes

    Energy Technology Data Exchange (ETDEWEB)

    Catherine, Arnaud, E-mail: arnocat@mnhn.fr [UMR7245 MCAM MNHN-CNRS, Muséum National d' Histoire Naturelle, CC 39, 12 rue Buffon, F-75231 Paris, Cedex 05 (France); Selma, Maloufi, E-mail: maloufi@mnhn.fr [UMR7245 MCAM MNHN-CNRS, Muséum National d' Histoire Naturelle, CC 39, 12 rue Buffon, F-75231 Paris, Cedex 05 (France); Mouillot, David, E-mail: david.mouillot@univ-montp2.fr [UMR 9190 MARBEC UM2-CNRS-IRD-UM1-IFREMER, CC 93, Place Eugène Bataillon, Université de Montpellier 2, F-34095 Montpellier (France); Troussellier, Marc, E-mail: troussel@univ-montp2.fr [UMR 9190 MARBEC UM2-CNRS-IRD-UM1-IFREMER, CC 93, Place Eugène Bataillon, Université de Montpellier 2, F-34095 Montpellier (France); Bernard, Cécile, E-mail: cbernard@mnhn.fr [UMR7245 MCAM MNHN-CNRS, Muséum National d' Histoire Naturelle, CC 39, 12 rue Buffon, F-75231 Paris, Cedex 05 (France)

    2016-07-15

    Local species richness (SR) is a key characteristic affecting ecosystem functioning. Yet, the mechanisms regulating phytoplankton diversity in freshwater ecosystems are not fully understood, especially in peri-urban environments where anthropogenic pressures strongly impact the quality of aquatic ecosystems. To address this issue, we sampled the phytoplankton communities of 50 lakes in the Paris area (France) characterized by a large gradient of physico-chemical and catchment-scale characteristics. We used large phytoplankton datasets to describe phytoplankton diversity patterns and applied a machine-learning algorithm to test the degree to which species richness patterns are potentially controlled by environmental factors. Selected environmental factors were studied at two scales: the lake-scale (e.g. nutrients concentrations, water temperature, lake depth) and the catchment-scale (e.g. catchment, landscape and climate variables). Then, we used a variance partitioning approach to evaluate the interaction between lake-scale and catchment-scale variables in explaining local species richness. Finally, we analysed the residuals of predictive models to identify potential vectors of improvement of phytoplankton species richness predictive models. Lake-scale and catchment-scale drivers provided similar predictive accuracy of local species richness (R{sup 2} = 0.458 and 0.424, respectively). Both models suggested that seasonal temperature variations and nutrient supply strongly modulate local species richness. Integrating lake- and catchment-scale predictors in a single predictive model did not provide increased predictive accuracy; therefore suggesting that the catchment-scale model probably explains observed species richness variations through the impact of catchment-scale variables on in-lake water quality characteristics. Models based on catchment characteristics, which include simple and easy to obtain variables, provide a meaningful way of predicting phytoplankton

  5. Interaction among non-toxic phytoplankton, toxic phytoplankton and zooplankton: inferences from field observations.

    Science.gov (United States)

    Roy, Shovonlal; Bhattacharya, Sabyasachi; Das, Partha; Chattopadhyay, Joydev

    2007-02-01

    We explore the mutual dependencies and interactions among different groups of species of the plankton population, based on an analysis of the long-term field observations carried out by our group in the North-West coast of the Bay of Bengal. The plankton community is structured into three groups of species, namely, non-toxic phytoplankton (NTP), toxic phytoplankton (TPP) and zooplankton. To find the pair-wise dependencies among the three groups of plankton, Pearson and partial correlation coefficients are calculated. To explore the simultaneous interaction among all the three groups, a time series analysis is performed. Following an Expectation Maximization (E-M) algorithm, those data points which are missing due to irregularities in sampling are estimated, and with the completed data set a Vector Auto-Regressive (VAR) model is analyzed. The overall analysis demonstrates that toxin-producing phytoplankton play two distinct roles: the inhibition on consumption of toxic substances reduces the abundance of zooplankton, and the toxic materials released by TPP significantly compensate for the competitive disadvantages among phytoplankton species. Our study suggests that the presence of TPP might be a possible cause for the generation of a complex interaction among the large number of phytoplankton and zooplankton species that might be responsible for the prolonged coexistence of the plankton species in a fluctuating biomass.

  6. Can Differentiated Production Planning and Control enable both Responsiveness and Efficiency in Food Production?

    Directory of Open Access Journals (Sweden)

    Anita Romsdal

    2014-07-01

    Full Text Available This paper addresses the complex production planning and control (PPC challenges in food supply chains. The study illustrates how food producers' traditional make‐to‐stock (MTS approach is not well suited to meet the trends of increasing product variety, higher demand uncertainty, increasing sales of fresh food products and more demanding customers. The paper proposes a framework for differentiated PPC that combines MTS with make‐to‐order (MTO.The framework matches products with the most appropriate PPC approaches and buffering techniques depending on market and product characteristics. The core idea is to achieve more volume flexibility in the production system by exploiting favourable product and market characteristics (high demand predictability, long customer order leadtime allowances and low product perishability. A case study is used to demonstrate how the framework can enable food producers to achieve efficiency in production, inventory and PPC processes – and simultaneously be responsive to market requirements.

  7. FPGA based Control of a Production Cell System

    NARCIS (Netherlands)

    Groothuis, Marcel A.; Zuijlen, van Jasper J.P.; Broenink, Jan F.

    2008-01-01

    Most motion control systems for mechatronic systems are implemented on digital computers. In this paper we present an FPGA based solution implemented on a low cost Xilinx Spartan III FPGA. A Production Cell setup with multiple parallel operating units is chosen as a test case. The embedded control s

  8. Modeling and control for closed environment plant production systems

    Science.gov (United States)

    Fleisher, David H.; Ting, K. C.; Janes, H. W. (Principal Investigator)

    2002-01-01

    A computer program was developed to study multiple crop production and control in controlled environment plant production systems. The program simulates crop growth and development under nominal and off-nominal environments. Time-series crop models for wheat (Triticum aestivum), soybean (Glycine max), and white potato (Solanum tuberosum) are integrated with a model-based predictive controller. The controller evaluates and compensates for effects of environmental disturbances on crop production scheduling. The crop models consist of a set of nonlinear polynomial equations, six for each crop, developed using multivariate polynomial regression (MPR). Simulated data from DSSAT crop models, previously modified for crop production in controlled environments with hydroponics under elevated atmospheric carbon dioxide concentration, were used for the MPR fitting. The model-based predictive controller adjusts light intensity, air temperature, and carbon dioxide concentration set points in response to environmental perturbations. Control signals are determined from minimization of a cost function, which is based on the weighted control effort and squared-error between the system response and desired reference signal.

  9. Inhibitory Control Predicts Language Switching Performance in Trilingual Speech Production

    Science.gov (United States)

    Linck, Jared A.; Schwieter, John W.; Sunderman, Gretchen

    2012-01-01

    This study investigated the role of domain-general inhibitory control in trilingual speech production. Taking an individual differences approach, we examined the relationship between performance on a non-linguistic measure of inhibitory control (the Simon task) and a multilingual language switching task for a group of fifty-six native English (L1)…

  10. Phytoplankton succession in recurrently fluctuating environments.

    Directory of Open Access Journals (Sweden)

    Daniel L Roelke

    Full Text Available Coastal marine systems are affected by seasonal variations in biogeochemical and physical processes, sometimes leading to alternating periods of reproductive growth limitation within an annual cycle. Transitions between these periods can be sudden or gradual. Human activities, such as reservoir construction and interbasin water transfers, influence these processes and can affect the type of transition between resource loading conditions. How such human activities might influence phytoplankton succession is largely unknown. Here, we employ a multispecies, multi-nutrient model to explore how nutrient loading switching mode might affect phytoplankton succession. The model is based on the Monod-relationship, predicting an instantaneous reproductive growth rate from ambient inorganic nutrient concentrations whereas the limiting nutrient at any given time was determined by Liebig's Law of the Minimum. When these relationships are combined with population loss factors, such as hydraulic displacement of cells associated with inflows, a characterization of a species' niche can be achieved through application of the R* conceptual model, thus enabling an ecological interpretation of modeling results. We found that the mode of reversal in resource supply concentrations had a profound effect. When resource supply reversals were sudden, as expected in systems influenced by pulsed inflows or wind-driven mixing events, phytoplankton were characterized by alternating succession dynamics, a phenomenon documented in inland water bodies of temperate latitudes. When resource supply reversals were gradual, as expected in systems influenced by seasonally developing wet and dry seasons, or annually occurring periods of upwelling, phytoplankton dynamics were characterized by mirror-image succession patterns. This phenomenon has not been reported previously in plankton systems but has been observed in some terrestrial plant systems. These findings suggest that a

  11. Phytoplankton succession in recurrently fluctuating environments.

    Science.gov (United States)

    Roelke, Daniel L; Spatharis, Sofie

    2015-01-01

    Coastal marine systems are affected by seasonal variations in biogeochemical and physical processes, sometimes leading to alternating periods of reproductive growth limitation within an annual cycle. Transitions between these periods can be sudden or gradual. Human activities, such as reservoir construction and interbasin water transfers, influence these processes and can affect the type of transition between resource loading conditions. How such human activities might influence phytoplankton succession is largely unknown. Here, we employ a multispecies, multi-nutrient model to explore how nutrient loading switching mode might affect phytoplankton succession. The model is based on the Monod-relationship, predicting an instantaneous reproductive growth rate from ambient inorganic nutrient concentrations whereas the limiting nutrient at any given time was determined by Liebig's Law of the Minimum. When these relationships are combined with population loss factors, such as hydraulic displacement of cells associated with inflows, a characterization of a species' niche can be achieved through application of the R* conceptual model, thus enabling an ecological interpretation of modeling results. We found that the mode of reversal in resource supply concentrations had a profound effect. When resource supply reversals were sudden, as expected in systems influenced by pulsed inflows or wind-driven mixing events, phytoplankton were characterized by alternating succession dynamics, a phenomenon documented in inland water bodies of temperate latitudes. When resource supply reversals were gradual, as expected in systems influenced by seasonally developing wet and dry seasons, or annually occurring periods of upwelling, phytoplankton dynamics were characterized by mirror-image succession patterns. This phenomenon has not been reported previously in plankton systems but has been observed in some terrestrial plant systems. These findings suggest that a transition from alternating

  12. [Pharmaceutical product quality control and good manufacturing practices].

    Science.gov (United States)

    Hiyama, Yukio

    2010-01-01

    This report describes the roles of Good Manufacturing Practices (GMP) in pharmaceutical product quality control. There are three keys to pharmaceutical product quality control. They are specifications, thorough product characterization during development, and adherence to GMP as the ICH Q6A guideline on specifications provides the most important principles in its background section. Impacts of the revised Pharmaceutical Affairs Law (rPAL) which became effective in 2005 on product quality control are discussed. Progress of ICH discussion for Pharmaceutical Development (Q8), Quality Risk Management (Q9) and Pharmaceutical Quality System (Q10) are reviewed. In order to reconstruct GMP guidelines and GMP inspection system in the regulatory agencies under the new paradigm by rPAL and the ICH, a series of Health Science studies were conducted. For GMP guidelines, product GMP guideline, technology transfer guideline, laboratory control guideline and change control system guideline were written. For the GMP inspection system, inspection check list, inspection memo and inspection scenario were proposed also by the Health Science study groups. Because pharmaceutical products and their raw materials are manufactured and distributed internationally, collaborations with other national authorities are highly desired. In order to enhance the international collaborations, consistent establishment of GMP inspection quality system throughout Japan will be essential.

  13. Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

    NARCIS (Netherlands)

    Thuroczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

    2012-01-01

    Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for > 70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe).

  14. Numerical Simulation of Nutrient and Phytoplankton Dynamics in Guangxi Coastal Bays, China

    Institute of Scientific and Technical Information of China (English)

    QIAO Xudong; WANG Baodong; SUN Xia; LIANG Shengkang

    2014-01-01

    The increasing riverine pollutants have resulted in nutrient enrichment and deterioration of water quality in the coastal water of Guangxi Province, China. However, the quantitative relationship between nutrient loads and water quality responses, which is crucial for developing eutrophication control strategies, is not well studied. In this study, the riverine fluxes of nutrients were quan-tified and integrated with nutrient cycling and phytoplankton dynamics by using box models for Guangxi coastal bays. The model concepts and biogeochemical equations were the same; while most model parameters were specific for each bay. The parameters were calibrated with seasonal observations during 2006-2007, and validated with yearly averaged measurements in 2009. The gen-eral features of nutrient and phytoplankton dynamics were reproduced, and the models were proved feasible under a wide range of bay conditions. Dissolved inorganic nitrogen was depleted during the spring algal bloom in Zhenzhu Bay and Fangcheng Bay with relatively less nutrient inputs. Phosphorus concentration was high in spring, which decreased then due to continuous phytoplankton consumption. Chlorophyll-a concentration reached its annual maximum in summer, but was the minimum in winter. Eutrophication was characterized by both an increase in nutrient concentrations and phytoplankton biomass in Lianzhou Bay. Either about 80%re-duction of nitrogen or 70%reduction of phosphorus was required to control the algal bloom in Lianzhou Bay. Defects of the models were discussed and suggestions to the environmental protection of Guangxi coastal bays were proposed.

  15. Responses of phytoplankton to experimental fertilization with ammonium and phosphate in an African soda lake.

    Science.gov (United States)

    Melack, John M; Kilham, Peter; Fisher, Thomas R

    1982-01-01

    Phytoplankton abundance in tropical lakes is more often judged to be limited by nitrogen than phosphorus, but seldom does the evidence include controlled enrichments of natural populations. In January 1980 we performed the first experimental fertilization in an equatorial African soda lake, Lake Sonachi, a small, meromictic volcanic crater lake in Kenya. During our study the natural phytoplankton abundance was ca. 80 μg chl a/l, and the euphotic zone PO4 and NH4 concentrations were less than 0.5 μM. In the monimolimnion PO4 reached 180 μM and NH4 reached 4,600 μM. Replicate polyethylene cylinders (5 m long, 1.2 m(3)) were enriched to attain 10 μM PO4 and 100 μM NH4. Phytoplankton responses were measured as chlorophyll, cell counts and particulate N, P and C. After two days, the chlorophyll increase in the P treatment was significantly higher than the control (PLake Sonachi sample was 21 and in samples from Lakes Bogoria and Elmenteita, two shallow soda lakes in Kenya, the ratios were 12 and 70 respectively. We conclude that limitation of phytoplankton abundance by phosphorus can occur even in some tropical African soda lakes.

  16. Primary production control of methane emission from wetlands

    Science.gov (United States)

    Whiting, G. J.; Chanton, J. P.

    1993-01-01

    Based on simultaneous measurements of CO2 and CH4 exchange in wetlands extending from subarctic peatlands to subtropical marshes, a positive correlation between CH4 emission and net ecosystem production is reported. It is suggested that net ecosystem production is a master variable integrating many factors which control CH4 emission in vegetated wetlands. It is found that about 3 percent of the daily net ecosystem production is emitted back to the atmosphere as CH4. With projected stimulation of primary production and soil microbial activity in wetlands associated with elevated atmospheric CO2 concentration, the potential for increasing CH4 emission from inundated wetlands, further enhancing the greenhouse effect, is examined.

  17. Spontaneous Assembly of Exopolymers from Phytoplankton

    Directory of Open Access Journals (Sweden)

    Yong-Xue Ding

    2009-01-01

    Full Text Available Phytoplankton exopolymeric substances (EPS contribute significantly to the dissolved organic car bon (DOC pool in the ocean, playing crucial roles in the surface ocean car bon cycle. Recent studies have demonstrated that ~10% of marine DOC can self-assemble as microgels through electro static Ca bonds providing hotspots of enriched microbial substrate. How ever, the question whether EPS can self-assemble and the formation mechanisms for EPS microgels have not been examined. Here were port that EPS from three representative phytoplankton species, Synechococcus, Emiliania huxleyi, and Skeletonema costatum can spontaneously self assemble in artificial sea water (ASW, forming microscopic gels of ~ 3 - 4 _ in diameter. Different from the marine DOC polymers assembly, these EPS samples can self-assemble in Ca2+-free ASW. Further experiments from fluorescence enhancement and chemical composition analysis confirmed the existence of fair amounts of hydrophobic domains in these EPS samples. These results suggest that hydrophobic interactions play a key role in the assembly of EPS from these three species of marine phytoplankton.

  18. Fluid dynamical niches of phytoplankton types.

    Science.gov (United States)

    d'Ovidio, Francesco; De Monte, Silvia; Alvain, Séverine; Dandonneau, Yves; Lévy, Marina

    2010-10-26

    The biogeochemical role of phytoplanktonic organisms strongly varies from one plankton type to another, and their relative abundance and distribution have fundamental consequences at the global and climatological scales. In situ observations find dominant types often associated to specific physical and chemical water properties. However, the mechanisms and spatiotemporal scales by which marine ecosystems are organized are largely not known. Here we investigate the spatiotemporal organization of phytoplankton communities by combining multisatellite data, notably high-resolution ocean-color maps of dominant types and altimetry-derived Lagrangian diagnostics of the surface transport. We find that the phytoplanktonic landscape is organized in (sub-)mesoscale patches (10-100 km) of dominant types separated by physical fronts induced by horizontal stirring. These physical fronts delimit niches supported by water masses of similar history and whose lifetimes are comparable with the timescale of the bloom onset (few weeks). The resonance between biological activity and physical processes suggest that the spatiotemporal (sub-)mesoscales associated to stirring are determinant in the observation and modeling of marine ecosystems.

  19. Run-to-run product quality control of batch processes

    Institute of Scientific and Technical Information of China (English)

    JIA Li; SHI Ji-ping; CHENG Da-shuai; CHIU Min-sen

    2009-01-01

    Batch processes have been increasingly used in the production of low volume and high value added products.Consequently,optimization control in batch processes is crucial in order to derive the maximum benefit.In this paper,a run-to-run product quality control based on iterative learning optimization control is developed.Moreover,a rigorous theorem is proposed and proven in this paper,which states that the tracking error under the optimal iterative learning control (ILC) law can converge to zero.In this paper,a typical nonlinear batch continuous stirred tank reactor (CSTR) is considered,and the results show that the performance of trajectory tracking is gradually improved by the ILC.

  20. Volcanism, Iron, and Phytoplankton in the Heard and McDonald Islands Region, Southern Indian Ocean

    Science.gov (United States)

    Coffin, M. F.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Trull, T. W.; Heobi in2016 v01 Shipboard Party, T.

    2016-12-01

    Phytoplankton supply approximately half of the oxygen in Earth's atmosphere, and iron supply limits the growth of phytoplankton in the anemic Southern Ocean. Situated entirely within the Indian Ocean sector of the Southern Ocean are Australia's only active subaerial volcanoes, Heard and McDonald islands (HIMI) on the central Kerguelen Plateau, a large igneous province. Widespread fields of submarine volcanoes, some of which may be active, extend for distances of up to several hundred kilometers from the islands. The predominantly eastward-flowing Antarctic Circumpolar Current sweeps across the central Kerguelen Plateau, and extensive blooms of phytoplankton are observed on the Plateau down-current of HIMI. The goal of RV Investigator voyage IN2016_V01, conducted in January/February 2016, is to test the hypothesis that hydrothermal fluids, which cool active submarine volcanoes in the HIMI region, ascend from the seafloor and fertilise surface waters with iron, thereby enhancing biological productivity beginning with phytoplankton. Significant initial shipboard results include: Documentation, for the first time, of the role of active HIMI and nearby submarine volcanoes in supplying iron to the Southern Ocean. Nearshore waters had elevated dissolved iron levels. Although biomass was not correspondingly elevated, fluorescence induction data indicated highly productive resident phytoplankton. Discovery of >200 acoustic plumes emanating from the seafloor and ascending up to tens of meters into the water column near HIMI. Deep tow camera footage shows bubbles rising from the seafloor in an acoustic plume field north of Heard Island. Mapping 1,000 km2 of uncharted seafloor around HIMI. Submarine volcanic edifices punctuate the adjacent seafloor, and yielded iron-rich rocks similar to those found on HIMI, respectively. Acoustic plumes emanating from some of these features suggest active seafloor hydrothermal systems.

  1. A comprehensive framework for functional diversity patterns of marine chromophytic phytoplankton using rbcL phylogeny

    Science.gov (United States)

    Samanta, Brajogopal; Bhadury, Punyasloke

    2016-02-01

    Marine chromophytes are taxonomically diverse group of algae and contribute approximately half of the total oceanic primary production. To understand the global patterns of functional diversity of chromophytic phytoplankton, robust bioinformatics and statistical analyses including deep phylogeny based on 2476 form ID rbcL gene sequences representing seven ecologically significant oceanographic ecoregions were undertaken. In addition, 12 form ID rbcL clone libraries were generated and analyzed (148 sequences) from Sundarbans Biosphere Reserve representing the world’s largest mangrove ecosystem as part of this study. Global phylogenetic analyses recovered 11 major clades of chromophytic phytoplankton in varying proportions with several novel rbcL sequences in each of the seven targeted ecoregions. Majority of OTUs was found to be exclusive to each ecoregion, whereas some were shared by two or more ecoregions based on beta-diversity analysis. Present phylogenetic and bioinformatics analyses provide a strong statistical support for the hypothesis that different oceanographic regimes harbor distinct and coherent groups of chromophytic phytoplankton. It has been also shown as part of this study that varying natural selection pressure on form ID rbcL gene under different environmental conditions could lead to functional differences and overall fitness of chromophytic phytoplankton populations.

  2. Grazers and phytoplankton growth in the oceans: an experimental and evolutionary perspective.

    Directory of Open Access Journals (Sweden)

    Simona Ratti

    Full Text Available The taxonomic composition of phytoplankton responsible for primary production on continental shelves has changed episodically through Earth history. Geological correlations suggest that major changes in phytoplankton composition correspond in time to changes in grazing and seawater chemistry. Testing hypotheses that arise from these correlations requires experimentation, and so we carried out a series of experiments in which selected phytoplankton species were grown in treatments that differed with respect to the presence or absence of grazers as well as seawater chemistry. Both protistan (Euplotes sp. and microarthropod (Acartia tonsa grazers changed the growth dynamics and biochemical composition of the green alga Tetraselmis suecica, the diatom Thalassiosira weissflogii, and the cyanobacterium Synechococcus sp., increasing the specific growth rate and palatability of the eukaryotic algae, while decreasing or leaving unchanged both parameters in the cyanobacteria. Synechococcus (especially and Thalassiosira produced toxins effective against the copepod, but ciliate growth was unaffected. Acartia induced a 4-6 fold increase of Si cell quota in the diatom, but Euplotes had no similar effect. The differential growth responses of the eukaryotic algae and cyanobacteria to ciliate grazing may help to explain the apparently coeval radiation of eukaryophagic protists and rise of eukaryotes to ecological prominence as primary producers in Neoproterozoic oceans. The experimental results suggest that phytoplankton responses to the later radiation of microarthropod grazers were clade-specific, and included changes in growth dynamics, toxin synthesis, encystment, and (in diatoms enhanced Si uptake.

  3. Measurement of phytoplankton photosynthesis rate using a pump-and-probe fluorometer

    Directory of Open Access Journals (Sweden)

    Taras K. Antal

    2001-09-01

    Full Text Available In this work we have studied the possibility of determining the rate of phytoplankton photosynthesis in situ using a submersible pump-and-probe fluorometer in water areas differing in their trophic level, as well as in climatic and hydrophysical characteristics. A biophysical model was used to describe the relationship between photosynthesis, underwater irradiance, and the intensity of phytoplankton fluorescence excited by an artificial light source. Fluorescence intensity was used as a measure of light absorption by phytoplankton and for assessing the efficiency of photochemical energy conversion at photosynthetic reaction centers. Parameters of the model that could not be measured experimentally were determined by calibrating fluorescence and irradiance data against the primary production measured in the Baltic Sea with the radioactive carbon method. It was shown that the standard deviation of these parameters in situ did not exceed 20%, and the use of their mean values to estimate the phytoplankton photosynthetic rate showed a good correlation between the calculated and meas

  4. Constraining the variability of optical properties in the Santa Barbara Channel, CA: A phytoplankton story

    Science.gov (United States)

    Barron, Rebecca Katherine

    approximately 16% of surface water data. Variability in CDOM spectral shape was quantified using the EOF technique, and regression analysis with EOF outputs showed that CDOM absorption intensity and spectral shape were well correlated dinoflagellate presence. Furthermore, results showed that phytoplankton biomass played a secondary role in relation to CDOM absorption, and that variability in CDOM absorption coefficients were primarily driven by community composition. CDOM quality in the SBC was also assessed using CDOM fluorescence properties via excitation emission matrix spectroscopy (EEMS). The EEMS data was analyzed using a multivariate statistical procedure, again, an EOF analysis, to identify three dominant CDOM source regimes: the surface pelagic regime, deep-water (up to 300 m) regime and kelp forest pelagic regime. This work also found that while CDOM absorption coefficient was strongly influence by which phytoplankton groups were present, DOM quality was characterized more so by the amount of phytoplankton biomass, hence indicating strong microbial component to DOM production. Lastly, with the use of the EEMS data, and characterization of CDOM absorption properties, e.g. spectral slope, S, slope ratio, SR, specific UV-absorbance, SUVA and MAA Index, we found that terrestrial sources of CDOM were very limited in the SBC. Based on this research, mineral particle concentrations that significantly correlated with IOPs were thought to be associated with suspended sediments from shoaling of the continental shelf rather than from stream/river influence. Thus, the SBC is a unique, optically complex ocean system where IOP dynamics, thus remote sensing reflectance, are strongly influenced by shifts in phytoplankton community structure.

  5. Phytoplankton composition of Sazlidere Dam lake, Istanbul, Turkey

    Directory of Open Access Journals (Sweden)

    Nese Yilmaz

    2013-05-01

    Full Text Available The phytoplankton composition of Sazlidere Dam lake was studied at 5 sampling sites between December 2003 - November 2005. A total of 67 taxa were recorded, representing Bacillariophyta (31, Chlorophyta (18, Cyanophyta (9, Chrysophyta (1, Cryptophyta (1, Dinophyta (3 and Euglenophyta (4. Bacillariophyta members constituted the dominant phytoplankton group in terms of species number. Nygaard’s compound index value and composition of phytoplankton indicate that the trophic state of Sazlidere Dam lake was changing from oligotrophic to mesotrophic.

  6. Control design for an autonomous wind based hydrogen production system

    Energy Technology Data Exchange (ETDEWEB)

    Valenciaga, F.; Evangelista, C.A. [CONICET, Laboratorio de Electronica Industrial Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata, CC.91, C.P. 1900, La Plata (Argentina)

    2010-06-15

    This paper presents a complete control scheme to efficiently manage the operation of an autonomous wind based hydrogen production system. This system comprises a wind energy generation module based on a multipolar permanent magnet synchronous generator, a lead-acid battery bank as short term energy storage and an alkaline von Hoerner electrolyzer. The control is developed in two hierarchical levels. The higher control level or supervisor control determines the general operation strategy for the whole system according to the wind conditions and the state of charge of the battery bank. On the other hand, the lower control level includes the individual controllers that regulate the respective module operation assuming the set-points determined by the supervisor control. These last controllers are approached using second-order super-twisting sliding mode techniques. The performance of the closed-loop system is assessed through representative computer simulations. (author)

  7. One-of-a-kind Production: Controller Algorithms for Real-time Control

    DEFF Research Database (Denmark)

    Ørum-Hansen, Claus

    PhD Dissertation.IPS2-programme - Integrated Production Systems - supportet by the Danish Technical Research Council, STVF.The project is a part of the IPS 2 research Programmme - Integrated Production System - with focus on one-of-a-kind production.The research area deals with controller...... algorithms for real-time control. The work includes practical cases from ship design and manufacturing. Cooperation with Odense Steel Shipyard....

  8. Methodical Grounds of Managing the Product Quality Control

    Directory of Open Access Journals (Sweden)

    Shapoval Olena A.

    2014-01-01

    Full Text Available The article analyses the modern state of products quality control management. It justifies a necessity of organisation of the quality control system under conditions of uninterrupted flow line production. It reveals problems connected with a low level of the products quality control management. It forms a set of factors of internal and external environments, which should be taken into account in the process of selection of a type of managerial actions by the products quality control. It considers specific features of identification of the most important factors at an enterprise on the basis of use of the matrix of strategic SWOT analysis. It offers a procedure of identification of a general assessment of factors of influence. It analyses a mechanism of use of main conceptual models, which reflect the system nature of quality management in an organisation – quality pyramids and quality loops. It proves a necessity of application of a principally new scheme of relations between the customer and enterprise, which envisages that requirements of the quality management system focus not on control and screening of semi-finished products, but on creation of conditions that exclude rejects. It considers the role of ISO 9000 in the system of quality management, which recommend the customers to make a preliminary assessment of activity of the producing enterprise.

  9. Ozone depletion - Ultraviolet radiation and phytoplankton biology in Antarctic waters

    Science.gov (United States)

    Smith, R. C.; Prezelin, B. B.; Baker, K. S.; Bidigare, R. R.; Boucher, N. P.; Coley, T.; Karentz, D.; Macintyre, S.; Matlick, H. A.; Menzies, D.

    1992-01-01

    The near-50-percent thinning of the stratospheric ozone layer over the Antarctic, with increased passage of mid-UV radiation to the surface of the Southern Ocean, has prompted concern over possible radiation damage to the near-surface phytoplankton communities that are the bases of Antarctic marine ecosystems. As the ozone layer thinned, a 6-week study of the marginal ice zone of the Bellingshousen Sea in the austral spring of 1990 noted sea-surface and depth-dependent ratios of mid-UV irradiance to total irradiance increased, and mid-UV inhibition of photosynthesis increased. A 6-12 percent reduction in primary production associated with ozone depletion was estimated to have occurred over the course of the present study.

  10. Product market competition, ultimate controlling structure and related party transactions

    Directory of Open Access Journals (Sweden)

    Shenglan Chen

    2012-12-01

    Full Text Available Previous studies have shown that product market competition has an important effect on corporate strategies and internal governance mechanisms. Using a sample of China’s listed firms from 2004 to 2009, we explore the relationship between product market competition and normal related party transactions and find a significant positive relationship. In addition, we investigate the substitutive effect of product market competition and the cash flow rights owned by ultimate controlling shareholders on the extent of normal related party transactions. In particular, our results suggest a positive relationship between the ultimate controlling shareholders’ cash flow rights and normal related party transactions that is strongest in noncompetitive industries and weakens as product market competition increases.

  11. Phytoplankton community structure in reservoirs of different trophic status, Northeast China

    Institute of Scientific and Technical Information of China (English)

    MA Chengxue; YU Hongxian

    2013-01-01

    The aim of this study was to determine the phytoplankton community structures of reservoirs of different trophic status,located in a cold region.Physical and chemical variables and the phytoplankton communities were investigated in two reservoirs (Xiquanyan Reservoir and Taoshan Reservoir) in Northeast China in 2009.The two reservoirs showed strong seasonal fluctuations in their physical and chemical composition.Results of the trophic status index indicated that Xiaquanyan Reservoir was mesotrophic,whilst Taoshan Reservoir was eutrophic.Diatoms were the dominant phytoplankton group in Xiquanyan Reservoir throughout all seasons of the study,while in Taoshan Reservoir,diatoms dominated in spring,and cyanobacteria dominated in summer and autumn.This difference was resulted from differences in local environmental factors,including nutrients and hydrology.This study suggests that in mesotrophic reservoirs,nutrients played a key role in controlling seasonal phytoplankton successions,whereas in eutrophic reservoirs water temperature was the key factor in a cold region.Notably,the dominant species in summer in the Taoshan Reservoir was Microcystis,which may produce toxins depending on the ambient conditions,and presenting a risk of local toxin contamination.

  12. Effects of inorganic nutrients in recycled water on freshwater phytoplankton biomass and composition.

    Science.gov (United States)

    Muhid, Priyanesh; Davis, Timothy W; Bunn, Stuart E; Burford, Michele A

    2013-01-01

    Planned indirect potable reuse water treated with advanced wastewater technologies (AWWT) to remove pollutants is increasingly being used to augment drinking water and groundwater supplies. While the treatment process substantially reduces the high nitrogen (N) and phosphorus (P) concentrations typically of wastewater, both nutrients can remain at concentrations and in biologically available forms that may stimulate phytoplankton growth in nutrient-deficient systems. This study examined the short-term effect of N plus P additions, at a range of concentrations, on phytoplankton growth and species composition in mesocosm experiments in a subtropical reservoir. Nitrate (NO(3)) plus orthophosphate (PO(4)) concentrations as low as 50 and 5 μg L(-1), respectively, resulted in significant increases in phytoplankton biomass, with a 3.99 μg L(-1) increase in chlorophyll a concentration with every 10 μg L(-1) increase in N plus 1 μg L(-1) in P. The system was likely to be co-limited because the addition of N or P alone did not result in increased chlorophyll a concentrations compared with the control. However, the toxic cyanobacterium, Cylindrospermopsis raciborskii, had higher growth rates with P addition alone. This study has shown that inputs of AWWT water have the potential to increase the phytoplankton biomass in this subtropical reservoir, at least in the short term. Therefore, the effect of AWWT water on water quality in reservoirs should be further investigated before widespread application occurs.

  13. A nonlocal and periodic reaction-diffusion-advection model of a single phytoplankton species.

    Science.gov (United States)

    Peng, Rui; Zhao, Xiao-Qiang

    2016-02-01

    In this article, we are concerned with a nonlocal reaction-diffusion-advection model which describes the evolution of a single phytoplankton species in a eutrophic vertical water column where the species relies solely on light for its metabolism. The new feature of our modeling equation lies in that the incident light intensity and the death rate are assumed to be time periodic with a common period. We first establish a threshold type result on the global dynamics of this model in terms of the basic reproduction number R0. Then we derive various characterizations of R0 with respect to the vertical turbulent diffusion rate, the sinking or buoyant rate and the water column depth, respectively, which in turn give rather precise conditions to determine whether the phytoplankton persist or become extinct. Our theoretical results not only extend the existing ones for the time-independent case, but also reveal new interesting effects of the modeling parameters and the time-periodic heterogeneous environment on persistence and extinction of the phytoplankton species, and thereby suggest important implications for phytoplankton growth control.

  14. Temperature affects the size-structure of phytoplankton communities in the ocean

    KAUST Repository

    López-Urrutia, Ángel

    2015-03-05

    The strong inverse correlation between resource availability and temperature in the ocean poses a challenge to determine the relative effect of these two variables on the size-structure of natural phytoplankton communities. Maranon et al (2012) compiled a dataset of concurrent temperature and resource level proxies that they claim disentangled the effect of temperature from that of resource supply. They concluded that the hypothesis that temperature per se plays a direct role in controlling phytoplankton size structure should be rejected. But our reanalysis of their data reaches a very different conclusion and suggests that they failed to separate the effects of temperature from the effects of resources. Although we obviously concur with Maranon et al (2012) in the long-known predominance of small phytoplankton cells under oligotrophic conditions, from our point of view this should not deter us from considering temperature as an important explanatory variable at a global scale since we show that, for the vast oligotrophic areas of the world\\'s oceans where chlorophyll concentrations are below <1 g L-1 temperature explains a high proportion of the variability in the size distribution of phytoplankton communities, a variability that can not be explained on the basis of the resource level proxies advocated by Maranon et al. (2012).

  15. Rhizobacterial characterization for quality control of eucalyptus biogrowth promoter products

    OpenAIRE

    Talyta Galafassi Zarpelon; Lúcio Mauro da Silva Guimarães; Poliane Alfenas-Zerbini; Eli Sidney Lopes; Reginaldo Gonçalves Mafia; Acelino Couto Alfenas

    2016-01-01

    Abstract Plant growth-promoting rhizobacteria strains from special formulations have been used to optimize eucalyptus cutting production. To undertake quality control for the formulated products, the rhizobacterial strains should be characterized to assess their purity and authentication. In the present study, we characterized nine strains of rhizobacteria, including three Bacillus subtilis (S1, S2 and 3918), two Pseudomonas sp. (MF4 and FL2), P. putida (MF2), P. fulva (Ca), Frateuria auranti...

  16. Effects of cadmium accumulation from suspended sediments and phytoplankton on the Oyster Saccostrea glomerata

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Helena A.; Maher, William A., E-mail: bill.maher@canberra.edu.au; Taylor, Anne M.; Krikowa, Frank

    2015-03-15

    Highlights: • Saccostrea glomerata accumulated cadmium from sediments and phytoplankton. • Effects were similar for both pathways. • Antioxidant capacity, lipid peroxidation and lysosomal destabilisation were affected. • Clear exposure–dose–response relationships were demonstrated. - Abstract: Metals are accumulated by filter feeding organisms via water, ingestion of suspended sediments or food. The uptake pathway can affect metal toxicity. Saccostrea glomerata were exposed to cadmium through cadmium-spiked suspended sediments (19 and 93 μg/g dry mass) and cadmium-enriched phytoplankton (1.6–3 μg/g dry mass) and cadmium uptake and effects measured. Oysters accumulated appreciable amounts of cadmium from both low and high cadmium spiked suspended sediment treatments (5.9 ± 0.4 μg/g and 23 ± 2 μg/g respectively compared to controls 0.97 ± 0.05 μg/g dry mass). Only a small amount of cadmium was accumulated by ingestion of cadmium-enriched phytoplankton (1.9 ± 0.1 μg/g compared to controls 1.2 ± 0.1 μg/g). In the cadmium spiked suspended sediment experiments, most cadmium was desorbed from sediments and cadmium concentrations in S. glomerata were significantly related to dissolved cadmium concentrations (4–21 μg/L) in the overlying water. In the phytoplankton feeding experiment cadmium concentrations in overlying water were <0.01 μg/L. In both exposure experiments, cadmium-exposed oysters showed a significant reduction in total antioxidant capacity and significantly increased lipid peroxidation and percentage of destabilised lysosomes. Destabilised lysosomes in the suspended sediments experiments also resulted from stress of exposure to the suspended sediments. The study demonstrated that exposure to cadmium via suspended sediments and to low concentrations of cadmium through the ingestion of phytoplankton, can cause sublethal stress to S. glomerata.

  17. Molecular biology in studies of oceanic primary production

    Energy Technology Data Exchange (ETDEWEB)

    LaRoche, J.; Falkowski, P.G. [Brookhaven National Lab., Upton, NY (United States); Geider, R. [Delaware Univ., Lewes, DE (United States). Coll. of Marine Studies

    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.

  18. Molecular biology in studies of oceanic primary production

    Energy Technology Data Exchange (ETDEWEB)

    LaRoche, J.; Falkowski, P.G. (Brookhaven National Lab., Upton, NY (United States)); Geider, R. (Delaware Univ., Lewes, DE (United States). 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.

  19. Climate versus geological controls on glacial meltwater micronutrient production in southern Greenland

    Science.gov (United States)

    Aciego, S. M.; Stevenson, E. I.; Arendt, C. A.

    2015-08-01

    Low concentrations of micronutrients in subarctic North Atlantic surface waters limit phytoplankton growth. Iron, phosphorous, and silicon are all potentially bio-limiting nutrients; iron is the most well documented in the subarctic North Atlantic. Manganese, nickel, copper and zinc are also essential trace metals for phytoplankton cell function. However, the spatial and temporal variability in the flux of these elements to the subarctic North Atlantic is undercharacterized. Here we show new data from the meltseason peak in 2013 indicating that glacial meltwater from the southern tip of Greenland has elevated dissolved major and trace metal concentrations compared to glacial meltwater draining shorter melt season glacial catchments to the north. Fe concentrations range from 0.13 to 6.97 μM, Zn from 4 to 95 μM, and Si from 4 to 36 μM, all higher than the depleted surface waters of the subarctic North Atlantic. Measured hydrochemical data modeled by PHREEQC indicates meltwater is undersaturated in pyrite and silicate phases but supersaturated with respect to oxyhydroxides, hematite and goethite, all phases that precipitate Fe as colloids, of which the nanoparticle phases should remain biologically available. The variability in geologic units between the sites indicates that subglacial lithology is a minor but not the dominant control on meltwater chemistry. The disparity in concentrations is directly correlated with climate, and an extended melt season, suggesting that future warming in Greenland will lead to increased trace element, and potential micronutrient, flux to the subarctic North Atlantic surface waters.

  20. Will Global Change Effect Primary Productivity in Coastal Ecosystems?

    Science.gov (United States)

    Rothschild, Lynn J.; Peterson, David L. (Technical Monitor)

    1997-01-01

    Algae are the base of coastal food webs because they provide the source of organic carbon for the remaining members of the community. Thus, the rate that they produce organic carbon to a large extent controls the productivity of the entire ecosystem. Factors that control algal productivity range from the physical (e.g., temperature, light), chemical (e.g., nutrient levels) to the biological (e.g., grazing). Currently, levels of atmospheric carbon dioxide surficial fluxes of ultraviolet radiation are rising. Both of these environmental variables can have a profound effect on algal productivity. Atmospheric carbon dioxide may increase surficial levels of dissolved inorganic carbon. Our laboratory and field studies of algal mats and phytoplankton cultures under ambient and elevated levels of pCO2 show that elevated levels of inorganic carbon can cause an increase in photosynthetic rates. In some cases, this increase will cause an increase in phytoplankton numbers. There may be an increase in the excretion of fixed carbon, which in turn may enhance bacterial productivity. Alternatively, in analogy with studies on the effect of elevated pCO2 on plants, the phytoplankton could change their carbon to nitrogen ratios, which will effect the feeding of the planktonic grazers. The seasonal depletion of stratospheric ozone has resulted in elevated fluxes of UVB radiation superimposed on the normal seasonal variation. Present surface UV fluxes have a significant impact on phytoplankton physiology, including the inhibition of the light and dark reactions of photosynthesis, inhibition of nitrogenase activity, inhibition of heterocyst formation, reduction in motility, increased synthesis of the UV-screening pigment scytonemin, and mutation. After reviewing these issues, recent work in our lab on measuring the effect of UV radiation on phytoplankton in the San Francisco Bay Estuary will be presented.

  1. The response of San Francisco Bay Delta phytoplankton communities to experimental ammonium, nitrate, and wastewater effluent additions and changes in irradiance

    Science.gov (United States)

    Strong, A. L.; van Dijken, G.; Mills, M. M.; Huang, I. B.; Francis, C.; Monismith, S. G.; Arrigo, K. R.

    2016-02-01

    The Bay Delta ecosystem exhibits unusually low levels of productivity, given the high levels of inorganic nutrient loading to the system. It has been suggested that anthropogenic ammonium (NH4+) loading inhibits diatom nitrate (NO3-) uptake and ultimately prevents blooms from occurring. From May 5-May 9, 2015, we conducted experimental manipulations and water column profiling research in the Bay Delta, in order to assess the ecological effects of anthropogenic nitrogen loading in the lower Sacramento River on phytoplankton growth, community structure, and dissolved inorganic nitrogen (N) uptake rates. We collected surface water at three locations, two located above and one below the Sacramento Regional wastewater treatment plant's diffuser pipe and incubated water for 48 hours. Experimental treatments included control, +NH4+ to 60 µM, +NO3- to 7.5 µM, and added whole wastewater effluent containing 60 µM NH4+. The water was incubated at ambient water temperature in 10-L cubitainers at two light levels: 50% and 5% of surface irradiance. Over two days, chlorophyll a (Chl a) concentrations increased seven-fold in response to both the +NH4+ and effluent additions at the upstream stations in the 50% light treatment, suggesting strong phytoplankton growth in response to added NH4+. Organic carbon accumulation showed similar patterns, and inorganic nutrients, including dissolved silica were all significantly drawn down. At all stations, Chl a accumulation was strongly affected by light limitation in the 5% light treatment. We also report changes in phytoplankton community structure, based on microscopy enumeration and HPLC pigment analysis. among treatments over the 48 hours. Additionally, we assessed variations in NO3- and NH4+ uptake and CO2 fixation across treatments over the course of the incubation. Taken as a whole, our results suggest that NH4+ from wastewater effluent does not inhibit phytoplankton growth in the Bay Delta, contrary to what has been previously

  2. Discrimination of cheese products for authenticity control by infrared spectroscopy.

    Science.gov (United States)

    Hruzikova, Jana; Milde, David; Krajancova, Pavla; Ranc, Vaclav

    2012-02-22

    Quality and authenticity control serve as the customers' and manufacturers' insurance, and thus the development of analytical tools providing these tasks represents an important step of each product development. The control of authenticity in food manufacturing is even more important due to the direct influence of its products on the health of the population. This study sought to develop an easy to use and robust method for the authenticity control of cheese products. The method is based on the measurement of infrared spectra of the gas phase obtained by heating of selected cheese under controlled conditions. Two different procedures, that is, treatment of samples in a desiccator and their freeze-drying, were compared, and also various temperatures and heating times were studied. It was found that suitable fingerprint infrared spectra can be obtained by both techniques; however, freeze-drying offered faster analysis times. The sample heating temperature and time were evaluated using advanced statistical approaches, and it was found that suitable results could be obtained using 120 °C heating for 90 min. This method was tested for the authenticity control of two cheese families, Tvaruzky and Romadur, for which four cheese products were evaluated and successfully discriminated for each family. This method can be potentially used as a cheap and easy to use alternative to other commercially available options.

  3. Mesoscale and sub-mesoscale variability in phytoplankton community composition in the Sargasso Sea

    Science.gov (United States)

    Cotti-Rausch, Bridget E.; Lomas, Michael W.; Lachenmyer, Eric M.; Goldman, Emily A.; Bell, Douglas W.; Goldberg, Stacey R.; Richardson, Tammi L.

    2016-04-01

    The Sargasso Sea is a dynamic physical environment in which strong seasonal variability combines with forcing by mesoscale (~100 km) eddies. These drivers determine nutrient, light, and temperature regimes and, ultimately, the composition and productivity of the phytoplankton community. On four cruises (2011 and 2012; one eddy per cruise), we investigated links between water column structure and phytoplankton community composition in the Sargasso at a range of time and space scales. On all cruises, cyanobacteria (Prochlorococcus and Synechococcus) dominated the phytoplankton numerically, while haptophytes were the dominant eukaryotes (up to 60% of total chl-a). There were substantial effects of mesoscale and sub-mesoscale forcing on phytoplankton community composition in both spring and summer. Downwelling (in anticyclones) resulted in Prochlorococcus abundances that were 22-66% higher than at 'outside' stations. Upwelling (in cyclones) was associated with significantly higher abundances and POC biomass of nanoeukaryotes. In general, however, each eddy had its own unique characteristics. The center of anticyclone AC1 (spring 2011) had the lowest phytoplankton biomass (chl-a) of any eddy we studied and had lower nitrate+nitrite (N+N deep mixed layer, yet had relatively low nutrient concentrations. We observed a shift in the taxonomic composition of haptophytes between a coccolithophore-dominated community in C2 (98% of total haptophyte chl-a) and a non-coccolithophore community at BATS. In summer 2012, downwelling associated with anticyclone AC2 occurred at the edge of the eddy (not at the center), where AC2 interacted with a nearby cyclone. At the edge, we found significantly lower Synechococcus abundances and higher eukaryote chl-a compared to the center of AC2 and BATS. These along-transect nuances demonstrate the significance of small-scale perturbations that substantially alter phytoplankton community structure. Therefore, while seasonality in the North

  4. Viewing hybrid systems as products of control systems and automata

    Science.gov (United States)

    Grossman, R. L.; Larson, R. G.

    1992-01-01

    The purpose of this note is to show how hybrid systems may be modeled as products of nonlinear control systems and finite state automata. By a hybrid system, we mean a network of consisting of continuous, nonlinear control system connected to discrete, finite state automata. Our point of view is that the automata switches between the control systems, and that this switching is a function of the discrete input symbols or letters that it receives. We show how a nonlinear control system may be viewed as a pair consisting of a bialgebra of operators coding the dynamics, and an algebra of observations coding the state space. We also show that a finite automata has a similar representation. A hybrid system is then modeled by taking suitable products of the bialgebras coding the dynamics and the observation algebras coding the state spaces.

  5. Chinese vaccine products go global: vaccine development and quality control.

    Science.gov (United States)

    Xu, Miao; Liang, Zhenglun; Xu, Yinghua; Wang, Junzhi

    2015-05-01

    Through the continuous efforts of several generations, China has become one of the few countries in the world that is capable of independently addressing all the requirements by the Expanded Program on Immunization. Regulatory science is applied to continuously improve the vaccine regulatory system. Passing the prequalification by WHO has allowed Chinese vaccine products to go global. Chinese vaccine products not only secure disease prevention and control domestically but also serve the needs for international public health. This article describes the history of Chinese vaccine development, the current situation of Chinese vaccine industry and its contribution to the prevention and control of infectious diseases. We also share our experience of national quality control and vaccine regulation during the past decades. China's experience in vaccine development and quality control can benefit other countries and regions worldwide, including the developing countries.

  6. In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content.

    Science.gov (United States)

    Álvarez, Eva; Nogueira, Enrique; López-Urrutia, Ángel

    2017-04-01

    In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production.IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution.

  7. Annual cycles of phytoplankton biomass in the subarctic Atlantic and Pacific Ocean

    Science.gov (United States)

    Westberry, Toby K.; Schultz, Patrick; Behrenfeld, Michael J.; Dunne, John P.; Hiscock, Michael R.; Maritorena, Stephane; Sarmiento, Jorge L.; Siegel, David A.

    2016-02-01

    High-latitude phytoplankton blooms support productive fisheries and play an important role in oceanic uptake of atmospheric carbon dioxide. In the subarctic North Atlantic Ocean, blooms are a recurrent feature each year, while in the eastern subarctic Pacific only small changes in chlorophyll (Chl) are seen over the annual cycle. Here we show that when evaluated using phytoplankton carbon biomass (Cphyto) rather than Chl, an annual bloom in the North Pacific is evident and can even rival blooms observed in the North Atlantic. The annual increase in subarctic Pacific phytoplankton biomass is not readily observed in the Chl record because it is paralleled by light- and nutrient-driven decreases in cellular pigment levels (Cphyto:Chl). Specifically, photoacclimation and iron stress effects on Cphyto:Chl oppose the biomass increase, leading to only modest changes in bulk Chl. The magnitude of the photoacclimation effect is quantified using descriptors of the near-surface light environment and a photophysiological model. Iron stress effects are diagnosed from satellite chlorophyll fluorescence data. Lastly, we show that biomass accumulation in the Pacific is slower than that in the Atlantic but is closely tied to similar levels of seasonal nutrient uptake in both basins. Annual cycles of satellite-derived Chl and Cphyto are reproduced by in situ autonomous profiling floats. These results contradict the long-standing paradigm that environmental conditions prevent phytoplankton accumulation in the subarctic Northeast Pacific and suggest a greater seasonal decoupling between phytoplankton growth and losses than traditionally implied. Further, our results highlight the role of physiol