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Sample records for marine plankton comparative

  1. Bioprospecting Marine Plankton

    Directory of Open Access Journals (Sweden)

    Chris Bowler

    2013-11-01

    Full Text Available The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics.

  2. Origin of marine planktonic cyanobacteria.

    Science.gov (United States)

    Sánchez-Baracaldo, Patricia

    2015-12-01

    Marine planktonic cyanobacteria contributed to the widespread oxygenation of the oceans towards the end of the Pre-Cambrian and their evolutionary origin represents a key transition in the geochemical evolution of the Earth surface. Little is known, however, about the evolutionary events that led to the appearance of marine planktonic cyanobacteria. I present here phylogenomic (135 proteins and two ribosomal RNAs), Bayesian relaxed molecular clock (18 proteins, SSU and LSU) and Bayesian stochastic character mapping analyses from 131 cyanobacteria genomes with the aim to unravel key evolutionary steps involved in the origin of marine planktonic cyanobacteria. While filamentous cell types evolved early on at around 2,600-2,300 Mya and likely dominated microbial mats in benthic environments for most of the Proterozoic (2,500-542 Mya), marine planktonic cyanobacteria evolved towards the end of the Proterozoic and early Phanerozoic. Crown groups of modern terrestrial and/or benthic coastal cyanobacteria appeared during the late Paleoproterozoic to early Mesoproterozoic. Decrease in cell diameter and loss of filamentous forms contributed to the evolution of unicellular planktonic lineages during the middle of the Mesoproterozoic (1,600-1,000 Mya) in freshwater environments. This study shows that marine planktonic cyanobacteria evolved from benthic marine and some diverged from freshwater ancestors during the Neoproterozoic (1,000-542 Mya).

  3. Mixotrophy in the marine plankton

    DEFF Research Database (Denmark)

    Stoecker, Diane K.; Hansen, Per Juel; Caron, David

    2017-01-01

    Mixotrophs are important components of the bacterioplankton, phytoplankton, microzooplankton, and (sometimes) zooplankton in coastal and oceanic waters. Bacterivory among the phytoplankton may be important for alleviating inorganic nutrient stress and may increase primary production in oligotrophic...... waters. Mixotrophic phytoflagellates and dinoflagellates are often dominant components of the plankton during seasonal stratification. Many of the microzooplankton grazers, including ciliates and Rhizaria, are mixotrophic owing to their retention of functional algal organelles or maintenance of algal...

  4. Sexual selection in marine plankton

    DEFF Research Database (Denmark)

    Sichlau, Mie Hylstofte

    Copepods are among the most abundant metazoans on the planet and play an important role in the marine food web. Many aspects of their ecology have consequently been studied, including details of their reproductive biology and mating behaviour. Sexual selection, the part of evolution which selects...

  5. Developmental Stages of some Tropical and Subtropical Planktonic Marine Copepods

    NARCIS (Netherlands)

    Björnberg, Tagea K.S.

    1972-01-01

    Most planktonic marine copepods have nauplii which differ greatly from the copepodids so that it is difficult to relate them to the adult form. Rearing experiments are usually unsuccessful; only 8% of ca. 800 species of planktonic marine copepods have identified nauplii (see below cited list). To

  6. Ether lipids of planktonic archae in the marine water column

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Hoefs, M.J.L.; Schouten, S.; King, L.L.; Wakeham, S.G.; Leeuw, J.W. de

    1997-01-01

    Acyclic and cyclic biphytanes derived from the membrane ether lipids of archaea were found in water column particulate and sedimentary organic matter from several oxic and anoxic marine environments. Compound-specific isotope analyses of the carbon skeletons suggest that planktonic archaea utilize

  7. Limits to gene flow in a cosmopolitan marine planktonic diatom.

    Science.gov (United States)

    Casteleyn, Griet; Leliaert, Frederik; Backeljau, Thierry; Debeer, Ann-Eline; Kotaki, Yuichi; Rhodes, Lesley; Lundholm, Nina; Sabbe, Koen; Vyverman, Wim

    2010-07-20

    The role of geographic isolation in marine microbial speciation is hotly debated because of the high dispersal potential and large population sizes of planktonic microorganisms and the apparent lack of strong dispersal barriers in the open sea. Here, we show that gene flow between distant populations of the globally distributed, bloom-forming diatom species Pseudo-nitzschia pungens (clade I) is limited and follows a strong isolation by distance pattern. Furthermore, phylogenetic analysis implies that under appropriate geographic and environmental circumstances, like the pronounced climatic changes in the Pleistocene, population structuring may lead to speciation and hence may play an important role in diversification of marine planktonic microorganisms. A better understanding of the factors that control population structuring is thus essential to reveal the role of allopatric speciation in marine microorganisms.

  8. [Research advances in ecological stoichiometry of marine plankton].

    Science.gov (United States)

    Chen, Lei; Li, Chao-Lun

    2014-10-01

    Ecological stoichiometry can be simply defined as: The biology of elements from molecules to the biosphere, which spans all levels of the environment and of the life. It's a new idea to build a unified theory and becomes an inevitable trend to develop the ecological science. Marine ecosystems, which contribute to 50% of the biosphere biomass, are the important component of the global biogeochemical cycles. Marine zooplankton plays an important role in the material circulation and energy flow of marine ecosystems and serves as a connecting link between the preceding and the following in a more precise understanding of the key elemental cycles. However, research on ecological stoichiometry of marine plankton is fragmentary and rare. This article summarized the ecological phenomena and mechanisms of limiting elements affecting marine plankton, the response of biochemical substances to nutrition limitation, and the food chain transmission and feedback of nutrition limitation. Meanwhile, we also put forward some perspectives for future research of ecological stoichiometry of plankton in China' s seas.

  9. Chemical ecology of the marine plankton.

    Science.gov (United States)

    Roy, Jessie S; Poulson-Ellestad, Kelsey L; Drew Sieg, R; Poulin, Remington X; Kubanek, Julia

    2013-10-11

    This review summarizes recent work in the chemical ecology of pelagic marine ecosystems. In order to provide a comprehensive overview of advances in the field over the period covered, we have organized this review by ecological interaction type beginning with intraspecific interactions, then interspecific interactions (including mutualism, parasitism, competition, and predation), and finally community- and ecosystem-wide interactions.

  10. Quasi-planktonic behavior of foraging top marine predators

    Science.gov (United States)

    Della Penna, Alice; de Monte, Silvia; Kestenare, Elodie; Guinet, Christophe; D'Ovidio, Francesco

    2015-12-01

    Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels.

  11. Scaling of fecundity, growth and development in marine planktonic copepods

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Sabatini, M.

    1995-01-01

    We compiled information from the literature on female and egg sizes and maximum egg production, growth and developmental rates in marine planktonic copepods. While specific growth and developmental rates are invariant with body mass, weight- specific fecundity scales with female body mass(-0...... to 50% and have weight-specific fecundities that are 2.5 times and egg production rates that are 7.5 times those of the former, Nauplii develop faster (by a factor of 2) but grow slower (by 20 to 40%) than copepodites in both spawning types. The main demographic implications of these findings are (1...

  12. Magnetic light cloaking control in the marine planktonic copepod Sapphirina

    Science.gov (United States)

    Kashiwagi, H.; Mizukawa, Y.; Iwasaka, M.; Ohtsuka, S.

    2017-05-01

    We investigated the light cloaking behavior of the marine planktonic copepod Sapphirina under a magnetic field. Optical interferences in the multi-laminated guanine crystal layer beneath the dorsal body surface create a brilliant structural color, which can be almost entirely removed by changing the light reflection. In the investigation, we immersed segments of Sapphirina in seawater contained in an optical chamber. When the derived Sapphirina segments were attached to the container surface, they were inert to magnetic fields up to 300 mT. However, when the back plate segments were attached to the substrate at a point, with most of the plate floating in the seawater, the plate rotated oppositely to the applied magnetic field. In addition, the brilliant parts of the Sapphirina back plate rotated backward and forward by changing the magnetic field directions. Our experiment suggests a new model of an optical micro-electro-mechanical system that is controllable by magnetic fields.

  13. Cenozoic planktonic marine diatom diversity and correlation to climate change

    Science.gov (United States)

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂18O (climate) and carbon cycle records (∂13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p2 were only moderately higher than today. Diversity is strongly correlated to both ∂13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  14. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    Directory of Open Access Journals (Sweden)

    David Lazarus

    Full Text Available Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂(18O (climate and carbon cycle records (∂(13C, and 20-0 Ma pCO2. Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p.9, detrended r>.6, all p<.001, but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  15. Marine plankton as an indicator of low-level radionuclide contamination in the Southern Ocean

    International Nuclear Information System (INIS)

    Marsh, K.V.; Buddemeier, R.W.

    1984-07-01

    We have initiated an investigation of the utility of marine plankton as bioconcentrating samplers of low-level marine radioactivity in the southern hemisphere. A literature review shows that both freshwater and marine plankton have trace element and radionuclide concentration factors (relative to water) of up to 10 4 . In the years 1956-1958, considerable work was done on the accumulation and distribution of a variety of fission and activation products produced by the nuclear tests in the Marshall Islands. Since then, studies have largely been confined to a few selected radionuclides, and by far most of this work has been done in the northern hemisphere. We participated in Operation Deepfreeze 1981, collecting 32 plankton samples from the U.S. Coast Guard Cutter Glacier on its Antarctic cruise, while Battelle Pacific Northwest Laboratories concurrently sampled air, water, rain and fallout. We were able to measure concentrations of the naturally occurring radionuclides 7 Be, 40 K and the U and th series, and we believe that we have detected low levels of 144 Ce and 95 Nb in seven samples ranging as far south as 68 0 . There is a definite association between the radionuclide content of plankton and air filters, suggesting that aerosol resuspension of marine radioactivity may be occurring. Biological identification of the plankton suggests a possible correlation between radionuclide concentration and foraminifera content of the samples. 38 references, 7 figures, 3 tables

  16. Global marine plankton functional type biomass distributions : Phaeocystis spp

    NARCIS (Netherlands)

    Vogt, M.; O'Brien, C.; Peloquin, J.; Schoemann, V.; Breton, E.; Estrada, M.; Gibson, J.; Karentz, D.; van Leeuwe, M. A.; Stefels, J.; Widdicombe, C.; Peperzak, L.

    2012-01-01

    The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to

  17. Assimilation of Ocean-Color Plankton Functional Types to Improve Marine Ecosystem Simulations

    Science.gov (United States)

    Ciavatta, S.; Brewin, R. J. W.; Skákala, J.; Polimene, L.; de Mora, L.; Artioli, Y.; Allen, J. I.

    2018-02-01

    We assimilated phytoplankton functional types (PFTs) derived from ocean color into a marine ecosystem model, to improve the simulation of biogeochemical indicators and emerging properties in a shelf sea. Error-characterized chlorophyll concentrations of four PFTs (diatoms, dinoflagellates, nanoplankton, and picoplankton), as well as total chlorophyll for comparison, were assimilated into a physical-biogeochemical model of the North East Atlantic, applying a localized Ensemble Kalman filter. The reanalysis simulations spanned the years 1998-2003. The skill of the reference and reanalysis simulations in estimating ocean color and in situ biogeochemical data were compared by using robust statistics. The reanalysis outperformed both the reference and the assimilation of total chlorophyll in estimating the ocean-color PFTs (except nanoplankton), as well as the not-assimilated total chlorophyll, leading the model to simulate better the plankton community structure. Crucially, the reanalysis improved the estimates of not-assimilated in situ data of PFTs, as well as of phosphate and pCO2, impacting the simulation of the air-sea carbon flux. However, the reanalysis increased further the model overestimation of nitrate, in spite of increases in plankton nitrate uptake. The method proposed here is easily adaptable for use with other ecosystem models that simulate PFTs, for, e.g., reanalysis of carbon fluxes in the global ocean and for operational forecasts of biogeochemical indicators in shelf-sea ecosystems.

  18. Proteorhodopsin lateral gene transfer between marine planktonic Bacteria and Archaea

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Martinez, Asuncion; Mincer, Tracy J

    2006-01-01

    Planktonic Bacteria, Archaea and Eukarya reside and compete in the ocean's photic zone under the pervasive influence of light. Bacteria in this environment were recently shown to contain photoproteins called proteorhodopsins, thought to contribute to cellular energy metabolism by catalysing light...... phylogenetic distribution of proteorhodopsins reflects their significant light-dependent fitness contributions, which drive the photoprotein's lateral acquisition and retention, but constrain its dispersal to the photic zone....

  19. Mortality of marine planktonic copepods : global rates and patterns

    DEFF Research Database (Denmark)

    Hirst, A.G.; Kiørboe, Thomas

    2002-01-01

    Using life history theory we make predictions of mortality rates in marine epi-pelagic copepods from field estimates of adult fecundity, development times and adult sex ratios. Predicted mortality increases with temperature in both broadcast and sac spawning copepods, and declines with body weight...... in broadcast spawners, while mortality in sac spawners is invariant with body size. Although the magnitude of copepod mortality does lie close to the overall general pattern for pelagic animals, copepod mortality scaling is much weaker, implying that small copepods are avoiding some mortality agent....../s that other pelagic animals of a similar size do not, We compile direct in situ estimates of copepod mortality and compare these with our indirect predictions; we find the predictions generally match the field measurements well with respect to average rates and patterns. Finally, by comparing in situ adult...

  20. Genomes of planktonic Acidimicrobiales: widening horizons for marine Actinobacteria by metagenomics.

    Science.gov (United States)

    Mizuno, Carolina Megumi; Rodriguez-Valera, Francisco; Ghai, Rohit

    2015-02-10

    The genomes of four novel marine Actinobacteria have been assembled from large metagenomic data sets derived from the Mediterranean deep chlorophyll maximum (DCM). These are the first marine representatives belonging to the order Acidimicrobiales and only the second group of planktonic marine Actinobacteria to be described. Their streamlined genomes and photoheterotrophic lifestyle suggest that they are planktonic, free-living microbes. A novel rhodopsin clade, acidirhodopsins, related to freshwater actinorhodopsins, was found in these organisms. Their genomes suggest a capacity to assimilate C2 compounds, some using the glyoxylate bypass and others with the ethylmalonyl-coenzyme A (CoA) pathway. They are also able to derive energy from dimethylsulfopropionate (DMSP), sulfonate, and carbon monoxide oxidation, all commonly available in the marine habitat. These organisms appear to be prevalent in the deep photic zone at or around the DCM. The presence of sister clades to the marine Acidimicrobiales in freshwater aquatic habitats provides a new example of marine-freshwater transitions with potential evolutionary insights. Despite several studies showing the importance and abundance of planktonic Actinobacteria in the marine habitat, a representative genome was only recently described. In order to expand the genomic repertoire of marine Actinobacteria, we describe here the first Acidimicrobidae genomes of marine origin and provide insights about their ecology. They display metabolic versatility in the acquisition of carbon and appear capable of utilizing diverse sources of energy. One of the genomes harbors a new kind of rhodopsin related to the actinorhodopsin clade of freshwater origin that is widespread in the oceans. Our data also support their preference to inhabit the deep chlorophyll maximum and the deep photic zone. This work contributes to the perception of marine actinobacterial groups as important players in the marine environment with distinct and

  1. Bioavailability of autochthonous dissolved organic nitrogen in marine plankton communities

    DEFF Research Database (Denmark)

    Knudsen, Helle; Markager, Svend Stiig; Søndergaard, Morten

    The purpose of this study was to investigate the bioavailability of dissolved organic nitrogen (DON) produced during a phytoplankton bloom. The experiments were conducted with natural plankton communities as batch growth experiments over approximately 30 days with nitrogen limitation. Five to six...... times during the exponential and stationary phases of each experimental bloom the bioavailability of DON was measured over 60 days together with DOC and oxygen consumption. The overall aim was to quantify remineralization of the added nitrate. The results showed that maximum 33 % of the added nitrate...

  2. Bio-PIXE marine science. Otoliths and plankton

    International Nuclear Information System (INIS)

    Malmqvist, K.G.; Buelow, K.; Elfman, M.; Kristiansson, P; Pallon, J.; Shariff, S.; Limburg, K.E.; Karlsson, C.

    1999-01-01

    Otoliths and phytoplanktons have been investigated using a nuclear microprobe. A brief description of sample preparation and irradiation conditions is given. The results indicate a great potential of the technique in marine sciences. (author)

  3. Reduced calcification of marine plankton in response to increased atmospheric CO2.

    Science.gov (United States)

    Riebesell, U; Zondervan, I; Rost, B; Tortell, P D; Zeebe, R E; Morel, F M

    2000-09-21

    The formation of calcareous skeletons by marine planktonic organisms and their subsequent sinking to depth generates a continuous rain of calcium carbonate to the deep ocean and underlying sediments. This is important in regulating marine carbon cycling and ocean-atmosphere CO2 exchange. The present rise in atmospheric CO2 levels causes significant changes in surface ocean pH and carbonate chemistry. Such changes have been shown to slow down calcification in corals and coralline macroalgae, but the majority of marine calcification occurs in planktonic organisms. Here we report reduced calcite production at increased CO2 concentrations in monospecific cultures of two dominant marine calcifying phytoplankton species, the coccolithophorids Emiliania huxleyi and Gephyrocapsa oceanica. This was accompanied by an increased proportion of malformed coccoliths and incomplete coccospheres. Diminished calcification led to a reduction in the ratio of calcite precipitation to organic matter production. Similar results were obtained in incubations of natural plankton assemblages from the north Pacific ocean when exposed to experimentally elevated CO2 levels. We suggest that the progressive increase in atmospheric CO2 concentrations may therefore slow down the production of calcium carbonate in the surface ocean. As the process of calcification releases CO2 to the atmosphere, the response observed here could potentially act as a negative feedback on atmospheric CO2 levels.

  4. Global marine plankton functional type biomass distributions: Phaeocystis spp.

    Directory of Open Access Journals (Sweden)

    C. Widdicombe

    2012-09-01

    Full Text Available The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to carbon biomass using species-specific carbon conversion factors. Microscopic counts of single-celled and colonial Phaeocystis were obtained both through the mining of online databases and by accepting direct submissions (both published and unpublished from Phaeocystis specialists. We recorded abundance data from a total of 1595 depth-resolved stations sampled between 1955–2009. The quality-controlled dataset includes 5057 counts of individual Phaeocystis cells resolved to species level and information regarding life-stages from 3526 samples. 83% of stations were located in the Northern Hemisphere while 17% were located in the Southern Hemisphere. Most data were located in the latitude range of 50–70° N. While the seasonal distribution of Northern Hemisphere data was well-balanced, Southern Hemisphere data was biased towards summer months. Mean species- and form-specific cell diameters were determined from previously published studies. Cell diameters were used to calculate the cellular biovolume of Phaeocystis cells, assuming spherical geometry. Cell biomass was calculated using a carbon conversion factor for prymnesiophytes. For colonies, the number of cells per colony was derived from the colony volume. Cell numbers were then converted to carbon concentrations. An estimation of colonial mucus carbon was included a posteriori, assuming a mean colony size for each species. Carbon content per cell ranged from 9 pg C cell−1 (single-celled Phaeocystis antarctica to 29 pg C cell−1 (colonial Phaeocystis globosa. Non-zero Phaeocystis cell biomasses (without mucus carbon range from 2.9 × 10−5 to 5.4 × 103 μg C l−1, with a mean of 45.7 μg C

  5. Interactions of marine plankton with transuranic elements. II

    International Nuclear Information System (INIS)

    Fisher, N.S.; Bjerregaard, P.; Huynh-Ngoc, L.; Harvey, G.R.

    1983-01-01

    To assess the significance of naturally occurring dissolved organic matter (DOM) on complexation of transuranic elements in seawater, a series of bioassay experiments was conducted in which the effect of DOM on the accumulation of 241 Am, 237 Pu(III-IV), and 237 Pu(V-VI) by the marine diatom Thalassiosira pseudonana was measured. EDTA at 0.3 μM complexed both metals substantially, resulting in reduced radio-isotope uptake by the diatom; the greatest effect was on Pu(III-IV). In contrast, there was no apparent complexation of either element by equimolar concentrations of marine fulvic (MFA) or humic acids (MHA), naturally occurring photooxidizable DOM (uncharacterized), or diatom exudates, as none of these materials reduced isotope uptake; on the contrary, there were indications that some of this DOM enhanced transuranic bioaccumulation in the diatom slightly. Subsequent experiments showed this enhancement was probably due to complexation of transition metals by the DOM, leading to fewer ambient ions 'competing' for binding sites on the cells; 241 Am uptake rates were negatively correlated (r = -0.846, P<.01) with ΣASV-labile Cu + Zn + Cd + Pb. These experiments suggest that naturally occurring DOM may not appreciably complex Am or Pu or greatly affect their bioavailability in the sea. (Auth.)

  6. Reverse transcriptase genes are highly abundant and transcriptionally active in marine plankton assemblages

    KAUST Repository

    Lescot, Magali

    2015-11-27

    Genes encoding reverse transcriptases (RTs) are found in most eukaryotes, often as a component of retrotransposons, as well as in retroviruses and in prokaryotic retroelements. We investigated the abundance, classification and transcriptional status of RTs based on Tara Oceans marine metagenomes and metatranscriptomes encompassing a wide organism size range. Our analyses revealed that RTs predominate large-size fraction metagenomes (>5 μm), where they reached a maximum of 13.5% of the total gene abundance. Metagenomic RTs were widely distributed across the phylogeny of known RTs, but many belonged to previously uncharacterized clades. Metatranscriptomic RTs showed distinct abundance patterns across samples compared with metagenomic RTs. The relative abundances of viral and bacterial RTs among identified RT sequences were higher in metatranscriptomes than in metagenomes and these sequences were detected in all metatranscriptome size fractions. Overall, these observations suggest an active proliferation of various RT-assisted elements, which could be involved in genome evolution or adaptive processes of plankton assemblage.

  7. Reverse transcriptase genes are highly abundant and transcriptionally active in marine plankton assemblages

    KAUST Repository

    Lescot, Magali; Hingamp, Pascal; Kojima, Kenji K; Villar, Emilie; Romac, Sarah; Veluchamy, Alaguraj; Boccara, Martine; Jaillon, Olivier; Ludicone, Daniele; Bowler, Chris; Wincker, Patrick; Claverie, Jean-Michel; Ogata, Hiroyuki

    2015-01-01

    Genes encoding reverse transcriptases (RTs) are found in most eukaryotes, often as a component of retrotransposons, as well as in retroviruses and in prokaryotic retroelements. We investigated the abundance, classification and transcriptional status of RTs based on Tara Oceans marine metagenomes and metatranscriptomes encompassing a wide organism size range. Our analyses revealed that RTs predominate large-size fraction metagenomes (>5 μm), where they reached a maximum of 13.5% of the total gene abundance. Metagenomic RTs were widely distributed across the phylogeny of known RTs, but many belonged to previously uncharacterized clades. Metatranscriptomic RTs showed distinct abundance patterns across samples compared with metagenomic RTs. The relative abundances of viral and bacterial RTs among identified RT sequences were higher in metatranscriptomes than in metagenomes and these sequences were detected in all metatranscriptome size fractions. Overall, these observations suggest an active proliferation of various RT-assisted elements, which could be involved in genome evolution or adaptive processes of plankton assemblage.

  8. Partitioning of organic production in marine plankton communities

    DEFF Research Database (Denmark)

    Conan, P.; Søndergaard, Morten; Kragh, T.

    2007-01-01

    We investigated the partitioning of carbon, nitrogen, and phosphorus between particulate and dissolved production using 11-m(3) marine mesocosms (bags) in a Norwegian fjord with a salinity of 28.3, a chlorophyll concentration of 0.6 mu g L-1, an even biomass among five algal groups, and nitrogen...... between 17 and 58 in the P-replete bags. The C: P ratio of new DOM in the +Si bags was about 300 at all dosing regimes. Consequently, the range in N: P ratios was also large, with values from below 1 to about 30. Carbon-rich DOM in oceans and coastal waters is not necessarily a function of a slow...

  9. Effects on the function of three trophic levels in marine plankton communities under stress from the antifouling compound zinc pyrithione

    International Nuclear Information System (INIS)

    Hjorth, M.; Dahlloef, I.; Forbes, V.E.

    2006-01-01

    This study aimed to investigate functional responses of natural marine planktonic communities to stress from the antifouling compound zinc pyrithione (ZPT). Isotope labelling techniques ( 14 C) were applied to study bacterial incorporation of leucine, photosynthetic activity of phytoplankton and grazing of labelled prey by zooplankton communities for 6 days after exposures to nominal concentrations of 0, 5, 25, 50 nM ZPT in a mesocosm experiment in Isefjord, Denmark. Significant direct effects were visible on chlorophyll a concentrations, which decreased in all exposed communities, to between 48 and 36% of control concentrations on Day 3, 1 day after the last exposure. Phytoplankton activities were also significantly affected on Day 3 with activities between 9 and 26% of control levels, as was zooplankton activities in the 25 and 50 nM exposures. In the 50 nM exposure the total community zooplankton activity was reduced to 25 ± 4%, and per individual to 46 ± 11% of control levels. Bacterial communities showed positive indirect effects with high activities (up to 183 ± 40%) due to higher amounts of available substrate from algal death. Pollution induced community tolerance analyses performed on phytoplankton and bacterial communities at the end of the experiment indicated a development of increased tolerance for phytoplankton in the 50 nM exposed communities, whereas there were no changes in tolerance in the bacterial communities. Multivariate analysis of the integrated functional response by the plankton communities revealed a significant difference (p < 0.05) between exposed communities compared to controls in the first 3 days after last exposure and in the end of the experiment. The study provides evidence of diverse effects on the functions of marine plankton communities under stress from a pollutant. Direct effects lead to cascading indirect effects throughout the community, eventually causing different developments. Continuous exposure to ZPT could lead to

  10. Marine Group II Dominates Planktonic Archaea in Water Column of the Northeastern South China Sea

    Directory of Open Access Journals (Sweden)

    Haodong Liu

    2017-06-01

    Full Text Available Temperature, nutrients, and salinity are among the important factors constraining the distribution and abundance of microorganisms in the ocean. Marine Group II (MGII belonging to Euryarchaeota commonly dominates the planktonic archaeal community in shallow water and Marine Group I (MGI, now is called Thaumarchaeota in deeper water in global oceans. Results of quantitative PCR (qPCR and 454 sequencing in our study, however, showed the dominance of MGII in planktonic archaea throughout the water column of the northeastern South China Sea (SCS that is characterized by strong water mixing. The abundance of ammonia-oxidizing archaea (AOA representing the main group of Thaumarchaeota in deeper water in the northeastern SCS was significantly lower than in other oceanic regions. Phylogenetic analysis showed that the top operational taxonomic units (OTUs of the MGII occurring predominantly below 200 m depth may be unique in the northeastern SCS based on the observation that they are distantly related to known sequences (identity ranging from 90–94%. The abundance of MGII was also significantly correlated with total bacteria in the whole column, which may indicate that MGII and bacteria may have similar physiological or biochemical properties or responses to environmental variation. This study provides valuable information about the dominance of MGII over AOA in both shallow and deep water in the northeastern SCS and highlights the need for comprehensive studies integrating physical, chemical, and microbial oceanography.

  11. Bacterioplankton: a sink for carbon in a coastal marine plankton community

    International Nuclear Information System (INIS)

    Ducklow, H.W.; Purdie, D.A.; Williams, P.J.LeB.; Davis, J.M.

    1986-01-01

    Recent determinations of high production rates (up to 30% of primary production in surface waters) implicate free-living marine bacterioplankton as a link in a microbial loop that supplements phytoplankton as food for herbivores. An enclosed water column of 300 cubic meters was used to test the microbial loop hypothesis by following the fate of carbon-14-labeled bacterioplankton for over 50 days. Only 2% of the label initially fixed from carbon-14-labeled glucose by bacteria was present in larger organisms after 13 days, at which time about 20% of the total label added remained in the particulate fraction. Most of the label appeared to pass directly from particles smaller than 1 micrometer (heterotrophic bacterioplankton and some bacteriovores) to respired labeled carbon dioxide or to regenerated dissolved organic carbon-14. Secondary (and, by implication, primary) production by organisms smaller than 1 micrometer may not be an important food source in marine food chains. Bacterioplankton can be a sink for carbon in planktonic food webs and may serve principally as agents of nutrient regeneration rather than as food

  12. Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

    International Nuclear Information System (INIS)

    Auger, P.A.; Machu, E.; Gorgues, T.; Grima, N.; Waeles, M.

    2015-01-01

    A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes

  13. Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

    Energy Technology Data Exchange (ETDEWEB)

    Auger, P.A., E-mail: pierreamael.auger@gmail.com [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Machu, E.; Gorgues, T.; Grima, N. [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Waeles, M. [Université de Bretagne Occidentale (UBO), Laboratoire de l' Environnement Marin (LEMAR), UMR-CNRS 6539/IRD/UBO, place N. Copernic, 29280 Plouzané (France)

    2015-02-01

    A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes.

  14. Addressing the impact of environmental uncertainty in plankton model calibration with a dedicated software system: the Marine Model Optimization Testbed (MarMOT 1.1 alpha)

    Science.gov (United States)

    Hemmings, J. C. P.; Challenor, P. G.

    2012-04-01

    A wide variety of different plankton system models have been coupled with ocean circulation models, with the aim of understanding and predicting aspects of environmental change. However, an ability to make reliable inferences about real-world processes from the model behaviour demands a quantitative understanding of model error that remains elusive. Assessment of coupled model output is inhibited by relatively limited observing system coverage of biogeochemical components. Any direct assessment of the plankton model is further inhibited by uncertainty in the physical state. Furthermore, comparative evaluation of plankton models on the basis of their design is inhibited by the sensitivity of their dynamics to many adjustable parameters. Parameter uncertainty has been widely addressed by calibrating models at data-rich ocean sites. However, relatively little attention has been given to quantifying uncertainty in the physical fields required by the plankton models at these sites, and tendencies in the biogeochemical properties due to the effects of horizontal processes are often neglected. Here we use model twin experiments, in which synthetic data are assimilated to estimate a system's known "true" parameters, to investigate the impact of error in a plankton model's environmental input data. The experiments are supported by a new software tool, the Marine Model Optimization Testbed, designed for rigorous analysis of plankton models in a multi-site 1-D framework. Simulated errors are derived from statistical characterizations of the mixed layer depth, the horizontal flux divergence tendencies of the biogeochemical tracers and the initial state. Plausible patterns of uncertainty in these data are shown to produce strong temporal and spatial variability in the expected simulation error variance over an annual cycle, indicating variation in the significance attributable to individual model-data differences. An inverse scheme using ensemble-based estimates of the

  15. Combined toxicity effects of chlorine, ammonia, and temperature on marine plankton. Progress report, September 16, 1975--September 30, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, J. C.; Ryther, J. H.

    1976-10-01

    Research on the combined effects of chlorine, ammmonia and temperature on marine plankton have been carried out for 20 months. To date continuous-flow bioassays have been conducted on lobster larvae (Homarus americanus), oyster larvae (Crassostrea virginica), copepods (Acartia tonsa), rotifers (Brachionus plicatilis), three juvenile and larval fish, killifish (Fundulus heteroclitus), scup (Stenotomus versicolor), and winter flounder (Pseudopleuronectes americanus), and phytoplankton (the diatom Phaeodactylum tricornutum). In addition, studies on zooplankton metabolism, filtration rates, and growth were carried out on exposed organisms. In general, the responses of invertebrates were distinctly different than those of fish: increasing mortality with increasing chlorine dose and greater sensitivity to chloramines than free chlorine in the former, and a threshold level of chlorine and greater sensitivity to free chlorine in the latter. Phytoplankton responses indicate that chlorine effects on primary producers are minimal compared to the serious effects on zooplankton, particularly larval forms that spawn intermittently. The overall conclusion of our studies is that chlorine application at power plants must be carried out with extreme caution and that serious consideration should be given to applying dechlorination at all coastal cooling systems.

  16. Comparative proteomic analysis of Listeria monocytogenes exposed to enterocin AS-48 in planktonic and sessile states.

    Science.gov (United States)

    Caballero Gómez, Natacha; Abriouel, Hikmate; Ennahar, Said; Gálvez, Antonio

    2013-10-15

    Enterocin AS-48 is a cyclic peptide of great interest for application in food preservation and sanitation. In the present study, the proteome response of Listeria monocytogenes to purified enterocin AS-48 was studied under two different conditions: planktonic cells and sessile cells grown on polystyrene plates. Ten different proteins were differentially expressed in planktonic L. monocytogenes cells treated with 0.1 μg/ml enterocin AS-48 compared to the untreated controls. Overexpressed proteins were related to stress response (DnaK) or carbohydrate transport and metabolism, while underexpressed and unexpressed proteins were related to metabolism (such as glyceraldehyde-3-phosphate dehydrogenase, pyruvate oxidase, glutamate dehydrogenase or glutamate decarboxylase) or stress (GroEL). In the sessile state, L. monocytogenes cells tolerated up to 10 μg/ml bacteriocin, and the treated biofilm cells overexpressed a set of 11 proteins, some of which could be related to stress response (DnaK, GroEL), protein synthesis and carbohydrate metabolism, while glyceraldehyde-3-phosphate dehydrogenase was the only unexpressed protein. Some of the overexpressed proteins (such as elongation factor Tu and GroEL) could also be implicated in cell adhesion. These results suggest different cell responses of L. monocytogenes to enterocin AS-48 in the planktonic and in the sessile state, including stress response and cell metabolism proteins. While in the planktonic state the bacterium may tend to compensate for the cytoplasmic cell permeability changes induced by AS-48 by reinforcing carbohydrate transport and metabolism, sessile cells seem to respond by shifting carbohydrate metabolism and reinforcing protein synthesis. Stress response proteins also seem to be important in the response to AS-48, but the stress response seems to be different in planktonic and in sessile cells. © 2013.

  17. Combined toxicity effects of chlorine, ammonia, and temperature on marine plankton. Progress report, November 1976--31 January 1978

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, J. C.

    1978-02-01

    Studies on the effects of chlorine, chloramines, and temperature on marine plankton have been carried out for three years. Species studied include marine phytoplankton, lobster larvae (Homarus americanus), oyster larvae (Crassostrea virginica), copepods (Acartia tonsa), rotifers (Brachionas plicatilis), grass shrimp (Palamonetes pugio) summer flounder larvae (Paralichthys dentatus), larval and juvenile killifish (Fundulus heteroclitus), juvenile scup (Stenotomus versicolor), and juvenile winter flounder (Pseudopleuronectes americanus). In addition extensive studies on chlorine chemistry in seawater have been carried out. The major conclusions are that entrainment effects on permanent plankton such as phytoplankton, copepods, and rotifers are temporary, that is those organisms surviving chlorination and temperature shocks are capable of renewed and unrestricted growth once returned to the receiving water. Because chlorine is only applied for short periods daily in most power plants, the total population of the above organisms actually exposed to chlorine is small and the effects may be hardly measurable in receiving waters. However, chlorination effects on larval species that spawn intermittently could be catastrophic. In addition, there are many unanswered questions regarding the fate of chlorine that is dissipated in marine waters. Are the losses real and, if so, do they pose a toxicity threat to marine biota.

  18. Comparative metatranscriptomics reveals decline of a neustonic planktonic population

    KAUST Repository

    Mojib, Nazia; Thimma, Manjula; Kumaran, M.; Sougrat, Rachid; Irigoien, Xabier

    2016-01-01

    The neuston layer in tropical seas provides a good model to study the effects of increased levels of different stressors (e.g., temperature, ultraviolet radiation and Trichodesmium blooms). Here, we use a comparative in situ metatranscriptomics approach to reveal the functional genomic composition of metabolically active neustonic mesozooplankton community in response to the summer conditions in the Red Sea. The neustonic population exhibited changes in composition and abundance with a significant decline in copepods and appendicularia in July, when Trichodesmium cells were more abundant along with high temperatures and UV-B radiation. Nearly 23,000 genes were differentially expressed at the community level when the metatranscriptomes of the neustonic zooplankton were compared in April, July, and October. On a wider Phylum level, the genes related to oxidative phosphorylation, carbon, nucleotides, amino acids, and lipids were significantly overrepresented in both arthropods and chordates in April and October. On organism level for copepods, expression of genes responsive to oxidative stress, defense against bacteria, immune response, and virus reproduction were increased along with the observed increased appearance of copepod carcasses in the samples collected during July. The differences in expression correspond either to secondary effects of the Trichodesmium bloom or more likely to the increased UV-B radiation in July. Given the dearth of information on the zooplankton gene expression in response to environmental stimuli, our study provides the first transcriptome landscape of the mesozooplankton community during a period of increased mortality of the copepod and appendicularia population.

  19. Comparative metatranscriptomics reveals decline of a neustonic planktonic population

    KAUST Repository

    Mojib, Nazia

    2016-10-20

    The neuston layer in tropical seas provides a good model to study the effects of increased levels of different stressors (e.g., temperature, ultraviolet radiation and Trichodesmium blooms). Here, we use a comparative in situ metatranscriptomics approach to reveal the functional genomic composition of metabolically active neustonic mesozooplankton community in response to the summer conditions in the Red Sea. The neustonic population exhibited changes in composition and abundance with a significant decline in copepods and appendicularia in July, when Trichodesmium cells were more abundant along with high temperatures and UV-B radiation. Nearly 23,000 genes were differentially expressed at the community level when the metatranscriptomes of the neustonic zooplankton were compared in April, July, and October. On a wider Phylum level, the genes related to oxidative phosphorylation, carbon, nucleotides, amino acids, and lipids were significantly overrepresented in both arthropods and chordates in April and October. On organism level for copepods, expression of genes responsive to oxidative stress, defense against bacteria, immune response, and virus reproduction were increased along with the observed increased appearance of copepod carcasses in the samples collected during July. The differences in expression correspond either to secondary effects of the Trichodesmium bloom or more likely to the increased UV-B radiation in July. Given the dearth of information on the zooplankton gene expression in response to environmental stimuli, our study provides the first transcriptome landscape of the mesozooplankton community during a period of increased mortality of the copepod and appendicularia population.

  20. Linking the planktonic and benthic habitat: genetic structure of the marine diatom Skeletonema marinoi.

    Science.gov (United States)

    Godhe, Anna; Härnström, Karolina

    2010-10-01

    Dormant life stages are important strategies for many aquatic organisms. The formation of resting stages will provide a refuge from unfavourable conditions in the water column, and their successive accumulation in the benthos will constitute a genetic reservoir for future planktonic populations. We have determined the genetic structure of a common bloom-forming diatom, Skeletonema marinoi, in the sediment and the plankton during spring, summer and autumn two subsequent years (2007-2009) in Gullmar Fjord on the Swedish west coast. Eight polymorphic microsatellite loci were used to assess the level of genetic differentiation and the respective gene diversity of the two different habitats. We also determined the degree of genetic differentiation between the seed banks inside the fjord and the open sea. The results indicate that Gullmar Fjord has one dominant endogenous population of S. marinoi, which is genetically differentiated from the open sea population. The fjord population is encountered in the plankton and in the sediment. Shifts from the dominant population can happen, and in our study, two genetically differentiated plankton populations, displaying reduced genetic diversity, occurred in September 2007 and 2008. Based on our results, we suggest that sill fjords maintain local long-lived and well-adapted protist populations, which continuously shift between the planktonic and benthic habitats. Intermittently, short-lived and mainly asexually reproducing populations can replace the dominant population in the water column, without influencing the genetic structure of the benthic seed bank. © 2010 Blackwell Publishing Ltd.

  1. Planktonic foraminiferal abnormalities in coastal and open marine eastern Mediterranean environments: A natural stress monitoring approach in recent and early Holocene marine systems

    Science.gov (United States)

    Antonarakou, A.; Kontakiotis, G.; Zarkogiannis, S.; Mortyn, P. G.; Drinia, H.; Koskeridou, E.; Anastasakis, G.

    2018-05-01

    Marine environmental status can be assessed through the study of bio-indicator species. Here, we monitor natural environmental stress by the occurrence of morphologically abnormal planktonic foraminiferal specimens from a suite of surface sediments in the eastern Mediterranean Sea. We also compare Scanning Electron Microscopy (SEM) abnormality observations from sapropel S1-derived sediments in the Aegean, Libyan and Levantine basins, since they provide a direct record of a natural stress experiment that took place over past time scales. At initial sapropel deposition levels, we observe increased growth asymmetry in Globigerinoides ruber twinned and twisted individuals, possibly associated with eutrophication and anoxia. In modern material, a range of malformations and aberrant morphologies from slight deformity with smaller or overdeveloped chambers to more severe deformity with abnormally protruding or misplaced chambers, distorted spirals, and double tests is also observed, as a result of the hypersaline, oligotrophic and oxygen-depleted nature of the Mediterranean Sea water column. Overall, we highlight the current use of the relative abundance of abnormal tests as a bio-indicator for monitoring natural stress, especially the occurrence of twin specimens as indicative of high-salinity stress conditions, and further illustrate the necessity to map both their spatial and temporal distribution for accurate paleoenvironmental reconstructions. Such an approach presents the advantage to rapidly provide information over wide spatial and temporal scales, extending our ability to monitor a wide variety of environments (from coastal to the open-sea). However, further investigations should extend this approach to test the robustness of our findings in a number of similar oceanic settings.

  2. Data integration for European marine biodiversity research: creating a database on benthos and plankton to study large-scale patterns and long-term changes

    NARCIS (Netherlands)

    Vandepitte, L.; Vanhoorne, B.; Kraberg, A.; Anisimova, N.; Antoniadou, C.; Araújo, R.; Bartsch, I.; Beker, B.; Benedetti-Cecchi, L.; Bertocci, I.; Cochrane, S.J.; Cooper, K.; Craeymeersch, J.A.; Christou, E.; Crisp, D.J.; Dahle, S.; de Boissier, M.; De Kluijver, M.; Denisenko, S.; De Vito, D.; Duineveld, G.; Escaravage, V.L.; Fleischer, D.; Fraschetti, S.; Giangrande, A.; Heip, C.H.R.; Hummel, H.; Janas, U.; Karez, R.; Kedra, M.; Kingston, P.; Kuhlenkamp, R.; Libes, M.; Martens, P.; Mees, J.; Mieszkowska, N.; Mudrak, S.; Munda, I.; Orfanidis, S.; Orlando-Bonaca, M.; Palerud, R.; Rachor, E.; Reichert, K.; Rumohr, H.; Schiedek, D.; Schubert, P.; Sistermans, W.C.H.; Sousa Pinto, I.S.; Southward, A.J.; Terlizzi, A.; Tsiaga, E.; Van Beusekom, J.E.E.; Vanden Berghe, E.; Warzocha, J.; Wasmund, N.; Weslawski, J.M.; Widdicombe, C.; Wlodarska-Kowalczuk, M.; Zettler, M.L.

    2010-01-01

    The general aim of setting up a central database on benthos and plankton was to integrate long-, medium- and short-term datasets on marine biodiversity. Such a database makes it possible to analyse species assemblages and their changes on spatial and temporal scales across Europe. Data collation

  3. Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition.

    Science.gov (United States)

    Alberti, Adriana; Poulain, Julie; Engelen, Stefan; Labadie, Karine; Romac, Sarah; Ferrera, Isabel; Albini, Guillaume; Aury, Jean-Marc; Belser, Caroline; Bertrand, Alexis; Cruaud, Corinne; Da Silva, Corinne; Dossat, Carole; Gavory, Frédérick; Gas, Shahinaz; Guy, Julie; Haquelle, Maud; Jacoby, E'krame; Jaillon, Olivier; Lemainque, Arnaud; Pelletier, Eric; Samson, Gaëlle; Wessner, Mark; Acinas, Silvia G; Royo-Llonch, Marta; Cornejo-Castillo, Francisco M; Logares, Ramiro; Fernández-Gómez, Beatriz; Bowler, Chris; Cochrane, Guy; Amid, Clara; Hoopen, Petra Ten; De Vargas, Colomban; Grimsley, Nigel; Desgranges, Elodie; Kandels-Lewis, Stefanie; Ogata, Hiroyuki; Poulton, Nicole; Sieracki, Michael E; Stepanauskas, Ramunas; Sullivan, Matthew B; Brum, Jennifer R; Duhaime, Melissa B; Poulos, Bonnie T; Hurwitz, Bonnie L; Pesant, Stéphane; Karsenti, Eric; Wincker, Patrick

    2017-08-01

    A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems.

  4. Laser damage to marine plankton and its application to checking biofouling and invasion by aquatic species: a laboratory study.

    Science.gov (United States)

    Nandakumar, Kanavillil; Obika, Hideki; Sreekumari, Kurissery; Utsumi, Akihiro; Ooie, Toshihiko; Yano, Tetsuo

    2009-01-01

    In this laboratory study, the ability of low-power pulsed laser irradiation to kill planktonic organisms in a flowing water system was examined, thus, to test the possibility of using this technique as a water treatment strategy to reduce biofouling growth in condenser tubes of power plants and to reduce bioinvasion via the ballast water of ships. Two flow rates (4.6 and 9.0 l h(-1)) were tested on three planktonic organisms: two marine centric diatoms viz. Skeletonema costatum and Chaetoceros gracilis and a dinoflagellate, Heterocapsa circularisquama. A low-power pulsed laser irradiation at 532 nm with a fluence of 0.1 J cm(-2) from a frequency-doubled Nd:YAG laser was used as the irradiation source. The laser irradiation resulted in a heavy mortality of the test cells. The mortality observed was >90% for S. costatum and H. circularisqama and >70% for C. gracilis. The results suggest that laser irradiation has the potential to act as a water treatment strategy to reduce biofouling of condenser tubes in power plants as well as to reduce species invasion via the ballast water of ships.

  5. Heterospecific mating and partial prezygotic reproductive isolation in the planktonic marine copepods Centropages typicus and Centropages hamatus

    DEFF Research Database (Denmark)

    Goetze, Erica

    2008-01-01

    Using three-dimensional (3D) video observations in laboratory experiments, I describe interspecific and intergeneric mating behaviors and motility patterns of the common planktonic marine copepods Centropages typicus, Centropages hamatus, and Temora longicornis. These observations are then used...... to estimate heterospecific and conspecific male mate-search volume rates and mate encounter rates in North Sea Centropages populations. Behavioral prezygotic reproductive isolation between Centropages species is incomplete, since males of each species pursued, contacted, captured, and, in rare cases, placed...... a spermatophore on the urosome of heterospecific females. T. longicornis males also detected the diffusible pheromone trail and pursued C. typicus females to the point of mate contact. Male mate-search tracking behavior was equally effective on diffusible pheromone trails of heterospecific and conspecific females...

  6. Influence of plankton community structure on the sinking velocity of marine aggregates

    Science.gov (United States)

    Bach, L. T.; Boxhammer, T.; Larsen, A.; Hildebrandt, N.; Schulz, K. G.; Riebesell, U.

    2016-08-01

    About 50 Gt of carbon is fixed photosynthetically by surface ocean phytoplankton communities every year. Part of this organic matter is reprocessed within the plankton community to form aggregates which eventually sink and export carbon into the deep ocean. The fraction of organic matter leaving the surface ocean is partly dependent on aggregate sinking velocity which accelerates with increasing aggregate size and density, where the latter is controlled by ballast load and aggregate porosity. In May 2011, we moored nine 25 m deep mesocosms in a Norwegian fjord to assess on a daily basis how plankton community structure affects material properties and sinking velocities of aggregates (Ø 80-400 µm) collected in the mesocosms' sediment traps. We noted that sinking velocity was not necessarily accelerated by opal ballast during diatom blooms, which could be due to relatively high porosity of these rather fresh aggregates. Furthermore, estimated aggregate porosity (Pestimated) decreased as the picoautotroph (0.2-2 µm) fraction of the phytoplankton biomass increased. Thus, picoautotroph-dominated communities may be indicative for food webs promoting a high degree of aggregate repackaging with potential for accelerated sinking. Blooms of the coccolithophore Emiliania huxleyi revealed that cell concentrations of 1500 cells/mL accelerate sinking by about 35-40%, which we estimate (by one-dimensional modeling) to elevate organic matter transfer efficiency through the mesopelagic from 14 to 24%. Our results indicate that sinking velocities are influenced by the complex interplay between the availability of ballast minerals and aggregate packaging; both of which are controlled by plankton community structure.

  7. Dynamics of autotrophic marine planktonic thaumarchaeota in the East China Sea.

    Science.gov (United States)

    Hu, Anyi; Yang, Zao; Yu, Chang-Ping; Jiao, Nianzhi

    2013-01-01

    The ubiquitous and abundant distribution of ammonia-oxidizing Thaumarchaeota in marine environments is now well documented, and their crucial role in the global nitrogen cycle has been highlighted. However, the potential contribution of Thaumarchaeota in the carbon cycle remains poorly understood. Here we present for the first time a seasonal investigation on the shelf region (bathymetry≤200 m) of the East China Sea (ECS) involving analysis of both thaumarchaeal 16S rRNA and autotrophy-related genes (acetyl-CoA carboxylase gene, accA). Quantitative PCR results clearly showed a higher abundance of thaumarchaeal 16S and accA genes in late-autumn (November) than summer (August), whereas the diversity and community structure of autotrophic Thaumarchaeota showed no statistically significant difference between different seasons as revealed by thaumarchaeal accA gene clone libraries. Phylogenetic analysis indicated that shallow ecotypes dominated the autotrophic Thaumarchaeota in the ECS shelf (86.3% of total sequences), while a novel non-marine thaumarchaeal accA lineage was identified in the Changjiang estuary in summer (when freshwater plumes become larger) but not in autumn, implying that Changjiang freshwater discharge played a certain role in transporting terrestrial microorganisms to the ECS. Multivariate statistical analysis indicated that the biogeography of the autotrophic Thaumarchaeota in the shelf water of the ECS was influenced by complex hydrographic conditions. However, an in silico comparative analysis suggested that the diversity and abundance of the autotrophic Thaumarchaeota might be biased by the 'universal' thaumarchaeal accA gene primers Cren529F/Cren981R since this primer set is likely to miss some members within particular phylogenetic groups. Collectively, this study improved our understanding of the biogeographic patterns of the autotrophic Thaumarchaeota in temperate coastal waters, and suggested that new accA primers with improved coverage

  8. Transfer of diazotroph-derived nitrogen towards non-diazotrophic planktonic communities: a comparative study between Trichodesmium erythraeum, Crocosphaera watsonii and Cyanothece sp.

    Science.gov (United States)

    Berthelot, Hugo; Bonnet, Sophie; Grosso, Olivier; Cornet, Véronique; Barani, Aude

    2016-07-01

    Biological dinitrogen (N2) fixation is the major source of new nitrogen (N) for the open ocean, and thus promotes marine productivity, in particular in the vast N-depleted regions of the surface ocean. Yet, the fate of the diazotroph-derived N (DDN) in marine ecosystems is poorly understood, and its transfer to auto- and heterotrophic surrounding plankton communities is rarely measured due to technical limitations. Moreover, the different diazotrophs involved in N2 fixation (Trichodesmium spp. vs. UCYN) exhibit distinct patterns of N2 fixation and inhabit different ecological niches, thus having potentially different fates in the marine food webs that remain to be explored. Here we used nanometer scale secondary ion mass spectrometry (nanoSIMS) coupled with 15N2 isotopic labelling and flow cytometry cell sorting to examine the DDN transfer to specific groups of natural phytoplankton and bacteria during artificially induced diazotroph blooms in New Caledonia (southwestern Pacific). The fate of the DDN was compared according to the three diazotrophs: the filamentous and colony-forming Trichodesmium erythraeum (IMS101), and the unicellular strains Crocosphaera watsonii WH8501 and Cyanothece ATCC51142. After 48 h, 7-17 % of the N2 fixed during the experiment was transferred to the dissolved pool and 6-12 % was transferred to non-diazotrophic plankton. The transfer was twice as high in the T. erythraeum bloom than in the C. watsonii and Cyanothece blooms, which shows that filamentous diazotrophs blooms are more efficient at promoting non-diazotrophic production in N-depleted areas. The amount of DDN released in the dissolved pool did not appear to be a good indicator of the DDN transfer efficiency towards the non-diazotrophic plankton. In contrast, the 15N-enrichment of the extracellular ammonium (NH4+) pool was a good indicator of the DDN transfer efficiency: it was significantly higher in the T. erythraeum than in unicellular diazotroph blooms, leading to a DDN

  9. Comparative transcriptome analysis of biofilm and planktonic cells of Bacillus cereus ATCC 14579

    NARCIS (Netherlands)

    Wijman, Janneke; Mols, M.; Tempelaars, Marcel; Abee, Tjakko

    2015-01-01

    Planktonic and biofilm cells of Bacillus cereus ATCC 14579 and ATCC 10987 were studied using microscopy and transcriptome analysis. By microscopy, clear differences could be observed between biofilm and planktonic cells as well as between the two strains. By using hierarchical clustering of the

  10. Comparative transcriptome analysis of biofilm and planktonic cells of Bacillus cereus ATCC 10987

    NARCIS (Netherlands)

    Wijman, Janneke; Mols, M.; Tempelaars, Marcel; Abee, Tjakko

    2015-01-01

    Planktonic and biofilm cells of Bacillus cereus ATCC 14579 and ATCC 10987 were studied using microscopy and transcriptome analysis. By microscopy, clear differences could be observed between biofilm and planktonic cells as well as between the two strains. By using hierarchical clustering of the

  11. A direct pre-screen for marine bacteria producing compounds inhibiting quorum sensing reveals diverse planktonic bacteria that are bioactive.

    Science.gov (United States)

    Linthorne, Jamie S; Chang, Barbara J; Flematti, Gavin R; Ghisalberti, Emilio L; Sutton, David C

    2015-02-01

    A promising new strategy in antibacterial research is inhibition of the bacterial communication system termed quorum sensing. In this study, a novel and rapid pre-screening method was developed to detect the production of chemical inhibitors of this system (quorum-quenching compounds) by bacteria isolated from marine and estuarine waters. This method involves direct screening of mixed populations on an agar plate, facilitating specific isolation of bioactive colonies. The assay showed that between 4 and 46 % of culturable bacteria from various samples were bioactive, and of the 95 selectively isolated bacteria, 93.7 % inhibited Vibrio harveyi bioluminescence without inhibiting growth, indicating potential production of quorum-quenching compounds. Of the active isolates, 21 % showed further activity against quorum-sensing-regulated pigment production by Serratia marcescens. The majority of bioactive isolates were identified by 16S ribosomal DNA (rDNA) amplification and sequencing as belonging to the genera Vibrio and Pseudoalteromonas. Extracts of two strongly bioactive Pseudoalteromonas isolates (K1 and B2) were quantitatively assessed for inhibition of growth and quorum-sensing-regulated processes in V. harveyi, S. marcescens and Chromobacterium violaceum. Extracts of the isolates reduced V. harveyi bioluminescence by as much as 98 % and C. violaceum pigment production by 36 % at concentrations which had no adverse effect on growth. The activity found in the extracts indicated that the isolates may produce quorum-quenching compounds. This study further supports the suggestion that quorum quenching may be a common attribute among culturable planktonic marine and estuarine bacteria.

  12. Synchrotron X-ray microscopy of marine calcifiers: how plankton record past climate change

    International Nuclear Information System (INIS)

    Redfern, S A T; Branson, O; Read, E

    2017-01-01

    We have used STXM and PEEM to reveal the underpinning chemistry and nanoscale structure behind palaeo-climate geochemical signatures, such as trace Mg in shells- proposed proxies for palaeo-ocean temperature. This has allowed us to test the chemical assumptions and mechanisms underpinning the use of such empirical proxies. We have determined the control on driving chemical variations in biogenic carbonates using STXM at the absorption edge of Mg, B, and Na in the shells of modern plankton. The power of these observations lies in their ability to link changes in chemistry, microstructure, and growth process in biogenic carbonate to environmental influences. We have seen that such changes occur at length scales of tens of nanometres and demonstrated that STXM provides an invaluable route to understanding chemical environment and key heterogeneity at the appropriate length scale. This new understanding provides new routes for future measurements of past climate variation in the sea floor fossil record. (paper)

  13. Effect of Low ph on Carbohydrate Production by a Marine Planktonic Diatom (Chaetoceros muelleri)

    International Nuclear Information System (INIS)

    Thornton, D.C.O.

    2009-01-01

    Rising carbon dioxide (CO 2 ) concentrations in the atmosphere due to human activity are causing the surface ocean to become more acidic. Diatoms play a pivotal role in biogeochemical cycling and ecosystem function in the ocean. ph affected the quantum efficiency of photosystem II and carbohydrate metabolism in a planktonic diatom (Chaetoceros muelleri), representative of a widely distributed genus. In batch cultures grown at low ph, the proportion of total carbohydrate stored within the cells decreased and more dissolved carbohydrates were exuded from the cells into the surrounding medium. Changes in productivity and the way in which diatoms allocate carbon into carbohydrates may affect ecosystem function and the efficiency of the biological carbon pump in a low ph ocean.

  14. Dynamics of autotrophic marine planktonic thaumarchaeota in the East China Sea.

    Directory of Open Access Journals (Sweden)

    Anyi Hu

    Full Text Available The ubiquitous and abundant distribution of ammonia-oxidizing Thaumarchaeota in marine environments is now well documented, and their crucial role in the global nitrogen cycle has been highlighted. However, the potential contribution of Thaumarchaeota in the carbon cycle remains poorly understood. Here we present for the first time a seasonal investigation on the shelf region (bathymetry≤200 m of the East China Sea (ECS involving analysis of both thaumarchaeal 16S rRNA and autotrophy-related genes (acetyl-CoA carboxylase gene, accA. Quantitative PCR results clearly showed a higher abundance of thaumarchaeal 16S and accA genes in late-autumn (November than summer (August, whereas the diversity and community structure of autotrophic Thaumarchaeota showed no statistically significant difference between different seasons as revealed by thaumarchaeal accA gene clone libraries. Phylogenetic analysis indicated that shallow ecotypes dominated the autotrophic Thaumarchaeota in the ECS shelf (86.3% of total sequences, while a novel non-marine thaumarchaeal accA lineage was identified in the Changjiang estuary in summer (when freshwater plumes become larger but not in autumn, implying that Changjiang freshwater discharge played a certain role in transporting terrestrial microorganisms to the ECS. Multivariate statistical analysis indicated that the biogeography of the autotrophic Thaumarchaeota in the shelf water of the ECS was influenced by complex hydrographic conditions. However, an in silico comparative analysis suggested that the diversity and abundance of the autotrophic Thaumarchaeota might be biased by the 'universal' thaumarchaeal accA gene primers Cren529F/Cren981R since this primer set is likely to miss some members within particular phylogenetic groups. Collectively, this study improved our understanding of the biogeographic patterns of the autotrophic Thaumarchaeota in temperate coastal waters, and suggested that new accA primers with

  15. Nitrogenase genes in non-cyanobacterial plankton: prevalence, diversity, and regulation in marine waters

    DEFF Research Database (Denmark)

    Riemann, Lasse; Farnelid, H.; Steward, G.F.

    2010-01-01

    Marine waters are generally considered to be nitrogen (N) limited and are therefore favourable environments for diazotrophs, i.e. organisms converting atmospheric N2 into ammonium or nitrogen oxides available for growth. In some regions, this import of N supports up to half of the primary...... productivity. Diazotrophic Cyanobacteria appear to be the major contributors to marine N2 fixation in surface waters, whereas the contribution of heterotrophic or chemoautotrophic diazotrophs to this process is usually regarded inconsequential. Culture-independent studies reveal that non......-cyanobacterial diazotrophs are diverse, widely distributed, and actively expressing the nitrogenase gene in marine and estuarine environments. The detection of nifH genes and nifH transcripts, even in N-replete marine waters, suggests that N2 fixation is an ecologically important process throughout the oceans. Because...

  16. Physiology, Fe(II oxidation, and Fe mineral formation by a marine planktonic cyanobacterium grown under ferruginous conditions

    Directory of Open Access Journals (Sweden)

    Elizabeth D. Swanner

    2015-10-01

    Full Text Available Evidence for Fe(II oxidation and deposition of Fe(III-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF. While the exact mechanisms of Fe(II oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II-rich waters in terms of growth, Fe uptake and homeostasis, and Fe mineral formation. We therefore grew the common marine cyanobacterium Synechococcus PCC 7002 in closed bottles that began anoxic, and contained Fe(II concentrations that span the range of possible concentrations in Precambrian seawater. These results, along with cell suspension experiments, indicate that Fe(II is likely oxidized by this strain via chemical oxidation with oxygen produced during photosynthesis, and not via any direct enzymatic or photosynthetic pathway. Imaging of the cell-mineral aggregates with scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM are consistent with extracellular precipitation of Fe(III (oxyhydroxide minerals, but that >10% of Fe(III sorbs to cell surfaces rather than precipitating. Proteomic experiments support the role of reactive oxygen species (ROS in Fe(II toxicity to Synechococcus PCC 7002. The proteome expressed under low Fe conditions included multiple siderophore biosynthesis and siderophore and Fe transporter proteins, but most siderophores are not expressed during growth with Fe(II. These results provide a mechanistic and quantitative framework for evaluating the geochemical consequences of perhaps life’s greatest metabolic innovation, i.e. the evolution and activity of oxygenic photosynthesis, in ferruginous

  17. Marine biogeography and evolution : Diversity patterns of planktonic gastropods and amphipods

    NARCIS (Netherlands)

    Burridge, A.K.

    2017-01-01

    Current changes in the oceans, including global warming and ocean acidification, are partially caused by human activity, unlike earlier episodes of change throughout geological history. Understanding and forecasting the responses of marine organisms to these changes is top priority for scientists,

  18. Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

    KAUST Repository

    Mesa, Elena; Delgado-Huertas, Antonio; Carrillo-de-Albornoz, Paloma; Garcí a-Corral, Lara S.; Sanz-Martí n, Marina; Wassmann, Paul; Reigstad, Marit; Sejr, Mikael; Dalsgaard, Tage; Duarte, Carlos M.

    2017-01-01

    Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton

  19. Insights into bioassessment of marine pollution using body-size distinctness of planktonic ciliates based on a modified trait hierarchy.

    Science.gov (United States)

    Xu, Henglong; Jiang, Yong; Xu, Guangjian

    2016-06-15

    Based on a modified trait hierarchy of body-size units, the feasibility for bioassessment of water pollution using body-size distinctness of planktonic ciliates was studied in a semi-enclosed bay, northern China. An annual dataset was collected at five sampling stations within a gradient of heavy metal contaminants. Results showed that: (1) in terms of probability density, the body-size spectra of the ciliates represented significant differences among the five stations; (2) bootstrap average analysis demonstrated a spatial variation in body-size rank patterns in response to pollution stress due to heavy metals; and (3) the average body-size distinctness (Δz(+)) and variation in body-size distinctness (Λz(+)), based on the modified trait hierarchy, revealed a clear departure pattern from the expected body-size spectra in areas with pollutants. These results suggest that the body-size diversity measures based on the modified trait hierarchy of the ciliates may be used as a potential indicator of marine pollution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Taxonomic and functional diversity of a coastal planktonic bacterial community in a river-influenced marine area.

    Science.gov (United States)

    Thiele, Stefan; Richter, Michael; Balestra, Cecilia; Glöckner, Frank Oliver; Casotti, Raffaella

    2017-04-01

    The Gulf of Naples is a dynamical area with intense exchanges between offshore oligotrophic and coastal eutrophic waters with frequent freshwater inputs. The Sarno River, one of the most polluted rivers in Europe, strongly contributes to the pollution of the area, discharging high amounts of heavy metals and organic wastes from heavily cultivated and industrial areas. This paper reports on the diversity and community structure of the marine residential Bacteria and Archaea of the Gulf of Naples in an area close to the river Sarno plume and investigates their small-scale taxonomic diversity and expression patterns as a proxy of potential metabolic activity using metagenomics and metatranscriptomics. Bacteria and Archaea were mainly represented by marine clades, with only minor contributors from freshwater ones. The community was dominated by Alpha- and Gammaproteobacteria, of which Rhodospirillales, Pelagibacteriales, and Oceanospirilalles were most represented. However, Alteromonadales and Rhodobacterales were the most active, despite their relative lower abundance, suggesting that they are important for overall ecosystem functioning and nutrient cycling. Nitrification and a reversed form of dissimilatory sulfate reduction were the major metabolic processes found in the metatrascriptomes and were mainly associated to Nitrosopumilales and Pelagibacter, respectively. No clear indication of transcripts related to stress induced by heavy metals or organic pollutants was found. In general, despite the high loads of pollutants discharged continuously by the Sarno River, the microbial community did not show marks of stress-induced changes neither structural nor functional, thus suggesting that this river has little or no effect on the planktonic bacterial community of the Gulf of Naples. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Diversity of marine planktonic ostracods in South China Sea: a DNA taxonomy approach.

    Science.gov (United States)

    Xu, Lei; Wang, Lianggen; Ning, Jiajia; Li, Hong; Ji, Yingying; Du, Feiyan

    2018-04-19

    Ostracods (Crustacea, Ostracoda) are small bivalved crustaceans, contributing over 200 described species to the marine zooplankton community. They are widely distributed and are relatively abundant components of the mesozooplankton, playing an important role in the transport of organic matter to deep layers. However, identification of ostracods based on micro-morphological characters is extremely difficult and time-consuming. Previous fragmentary taxonomic studies of ostracods in the South China Sea (SCA), were based solely on morphology. Here, by analysing the mitochondrial COI gene, we explore the taxa across the SCA using molecular tools for the first time. Our results show that sequence divergence among species varies within a large range, from 12.93% to 35.82%. Sixteen of the taxonomic units recovered by DNA taxonomy agree well with morphology, but Paraconchoecia oblonga, Conchoecia magna and Halocypris brevirostris split into two clades each, each of which contains cryptic species.

  2. Production and decomposition of new DOC by marine plankton communities: carbohydrates, refractory components and nutrient limitation

    DEFF Research Database (Denmark)

    Kragh, T.; Søndergaard, Morten

    2009-01-01

    The accumulation and biodegradation of dissolved organic carbon (DOC) and dissolved and particulate combined neutral sugars (DCNS, PCNS) were followed during a period of 22 days in experimental marine phytoplankton incubations. Five different growth regimes were established in 11 m(3) coastal...... in the mesocosms with diatoms dominating could be explained by DCNS, while only 6% was explained in the mesocosms with few diatoms. PCNS composition was similar in all mesocosms and with dominance of glucose and mannose, while DCNS were more evenly distributed with the following mole percentages fucose 15......, rhamnose 14, arabinose 6, galactose 27, glucose 20 and mannose 18%. The DCNS composition did not reflect the PCNS composition at any time during the experiment. Accumulated DCNS were quickly degraded and only 1% of the new RDOC was explained by DCNS. RDOC accumulated after day #17 in the two mesocosms...

  3. Mandibular gnathobases of marine planktonic copepods – feeding tools with complex micro- and nanoscale composite architectures

    Directory of Open Access Journals (Sweden)

    Jan Michels

    2015-03-01

    Full Text Available Copepods are dominant members of the marine zooplankton. Their diets often comprise large proportions of diatom taxa whose silicified frustules are mechanically stable and offer protection against grazers. Despite of this protection, many copepod species are able to efficiently break even the most stable frustule types. This ability requires specific feeding tools with mechanically adapted architectures, compositions and properties. When ingesting food, the copepods use the gnathobases of their mandibles to grab and, if necessary, crush and mince the food items. The morphology of these gnathobases is related to the diets of the copepods. Gnathobases of copepod species that mainly feed on phytoplankton feature compact and stable tooth-like structures, so-called teeth. In several copepod species these gnathobase teeth have been found to contain silica. Recent studies revealed that the siliceous teeth are complex microscale composites with silica-containing cap-like structures located on chitinous exoskeleton sockets that are connected with rubber-like bearings formed by structures with high proportions of the soft and elastic protein resilin. In addition, the silica-containing cap-like structures exhibit a nanoscale composite architecture. They contain some amorphous silica and large proportions of the crystalline silica type α-cristobalite and are pervaded by a fine chitinous fibre network that very likely serves as a scaffold during the silicification process. All these intricate composite structures are assumed to be the result of a coevolution between the copepod gnathobases and diatom frustules in an evolutionary arms race. The composites very likely increase both the performance of the siliceous teeth and their resistance to mechanical damage, and it is conceivable that their development has favoured the copepods’ dominance of the marine zooplankton observed today.

  4. UV-MAOR - UV-B-specific reactions of marine planktons. Final report

    International Nuclear Information System (INIS)

    Gerbersdorf, S.; Steeger, H.U.; Schubert, H.; Paul, R.J.

    2001-02-01

    An initial finding of the studies performed here is that under certain hydrogeographic and meteorological conditions vertical migration of phyto and zooplankton also occurs in near-shore parts of flat waters. The vertical migration of phytoplankton was induced by exceeding the threshold intensity of approx. 300 μmol photons m -2 s -1 (PAR). However, the sigmoidal course of the reaction of phytoplankton suggests that it is apparently not the PAR intensity alone but the ratio of PAR/UV-B which governs the downward migration. However, the present body of data is not sufficient for a definitive statistical verification of this finding. Light irradiation resulted in an increased density and thus in a reduced buoyancy of flounder spawn. This effect was primarily dependent on intensity and did not increase upon irradiation with UV-B, UV-A and PAR as compared to UV-A and PAR alone. Irradiation with UV-B did not influence the substance located in the vitellus whose absorption maximum was found to be 300 nm, probably gadusol

  5. Marine Biology

    Science.gov (United States)

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  6. Comparative assessment of antibiotic susceptibility of coagulase-negative staphylococci in biofilm versus planktonic culture as assessed by bacterial enumeration or rapid XTT colorimetry.

    Science.gov (United States)

    Cerca, Nuno; Martins, Silvia; Cerca, Filipe; Jefferson, Kimberly K; Pier, Gerald B; Oliveira, Rosário; Azeredo, Joana

    2005-08-01

    To quantitatively compare the antibiotic susceptibility of biofilms formed by the coagulase-negative staphylococci (CoNS) Staphylococcus epidermidis and Staphylococcus haemolyticus with the susceptibility of planktonic cultures. Several CoNS strains were grown planktonically or as biofilms to determine the effect of the mode of growth on the level of susceptibility to antibiotics with different mechanisms of action. The utility of a new, rapid colorimetric method that is based on the reduction of a tetrazolium salt (XTT) to measure cell viability was tested by comparison with standard bacterial enumeration techniques. A 6 h kinetic study was performed using dicloxacillin, cefazolin, vancomycin, tetracycline and rifampicin at the peak serum concentration of each antibiotic. In planktonic cells, inhibitors of cell wall synthesis were highly effective over a 3 h period. Biofilms were much less susceptible than planktonic cultures to all antibiotics tested, particularly inhibitors of cell wall synthesis. The susceptibility to inhibitors of protein and RNA synthesis was affected by the biofilm phenotype to a lesser degree. Standard bacterial enumeration techniques and the XTT method produced equivalent results both in biofilms and planktonic assays. This study provides a more accurate comparison between the antibiotic susceptibilities of planktonic versus biofilm populations, because the cell densities in the two populations were similar and because we measured the concentration required to inhibit bacterial metabolism rather than to eradicate the entire bacterial population. While the biofilm phenotype is highly resistant to antibiotics that target cell wall synthesis, it is fairly susceptible to antibiotics that target RNA and protein synthesis.

  7. In situ camera observations reveal major role of zooplankton in modulating marine snow formation during an upwelling-induced plankton bloom

    Science.gov (United States)

    Taucher, Jan; Stange, Paul; Algueró-Muñiz, María; Bach, Lennart T.; Nauendorf, Alice; Kolzenburg, Regina; Büdenbender, Jan; Riebesell, Ulf

    2018-05-01

    Particle aggregation and the consequent formation of marine snow alter important properties of biogenic particles (size, sinking rate, degradability), thus playing a key role in controlling the vertical flux of organic matter to the deep ocean. However, there are still large uncertainties about rates and mechanisms of particle aggregation, as well as the role of plankton community structure in modifying biomass transfer from small particles to large fast-sinking aggregates. Here we present data from a high-resolution underwater camera system that we used to observe particle size distributions and formation of marine snow (aggregates >0.5 mm) over the course of a 9-week in situ mesocosm experiment in the Eastern Subtropical North Atlantic. After an oligotrophic phase of almost 4 weeks, addition of nutrient-rich deep water (650 m) initiated the development of a pronounced diatom bloom and the subsequent formation of large marine snow aggregates in all 8 mesocosms. We observed a substantial time lag between the peaks of chlorophyll a and marine snow biovolume of 9-12 days, which is much longer than previously reported and indicates a marked temporal decoupling of phytoplankton growth and marine snow formation during our study. Despite this time lag, our observations revealed substantial transfer of biomass from small particle sizes (single phytoplankton cells and chains) to marine snow aggregates of up to 2.5 mm diameter (ESD), with most of the biovolume being contained in the 0.5-1 mm size range. Notably, the abundance and community composition of mesozooplankton had a substantial influence on the temporal development of particle size spectra and formation of marine snow aggregates: While higher copepod abundances were related to reduced aggregate formation and biomass transfer towards larger particle sizes, the presence of appendicularia and doliolids enhanced formation of large marine snow. Furthermore, we combined in situ particle size distributions with

  8. Ecological Stoichiometry of Ocean Plankton

    Science.gov (United States)

    Moreno, Allison R.; Martiny, Adam C.

    2018-01-01

    Marine plankton elemental stoichiometric ratios can deviate from the Redfield ratio (106C:16N:1P); here, we examine physiological and biogeochemical mechanisms that lead to the observed variation across lineages, regions, and seasons. Many models of ecological stoichiometry blend together acclimative and adaptive responses to environmental conditions. These two pathways can have unique molecular mechanisms and stoichiometric outcomes, and we attempt to disentangle the two processes. We find that interactions between environmental conditions and cellular growth are key to understanding stoichiometric regulation, but the growth rates of most marine plankton populations are poorly constrained. We propose that specific physiological mechanisms have a strong impact on plankton and community stoichiometry in nutrient-rich environments, whereas biogeochemical interactions are important for the stoichiometry of the oligotrophic gyres. Finally, we outline key areas with missing information that is needed to advance understanding of the present and future ecological stoichiometry of ocean plankton.

  9. Estimating cyclopoid copepod species richness and geographical distribution (Crustacea across a large hydrographical basin: comparing between samples from water column (plankton and macrophyte stands

    Directory of Open Access Journals (Sweden)

    Gilmar Perbiche-Neves

    2014-06-01

    Full Text Available Species richness and geographical distribution of Cyclopoida freshwater copepods were analyzed along the "La Plata" River basin. Ninety-six samples were taken from 24 sampling sites, twelve sites for zooplankton in open waters and twelve sites for zooplankton within macrophyte stands, including reservoirs and lotic stretches. There were, on average, three species per sample in the plankton compared to five per sample in macrophytes. Six species were exclusive to the plankton, 10 to macrophyte stands, and 17 were common to both. Only one species was found in similar proportions in plankton and macrophytes, while five species were widely found in plankton, and thirteen in macrophytes. The distinction between species from open water zooplankton and macrophytes was supported by nonmetric multidimensional analysis. There was no distinct pattern of endemicity within the basin, and double sampling contributes to this result. This lack of sub-regional faunal differentiation is in accordance with other studies that have shown that cyclopoids generally have wide geographical distribution in the Neotropics and that some species there are cosmopolitan. This contrasts with other freshwater copepods such as Calanoida and some Harpacticoida. We conclude that sampling plankton and macrophytes together provided a more accurate estimate of the richness and geographical distribution of these organisms than sampling in either one of those zones alone.

  10. The effects of the Sea Empress oil spill on the plankton of the southern Irish Sea

    International Nuclear Information System (INIS)

    Batten, S.; Allen, R.; Wotton, C.

    1997-07-01

    This report describes the methodology used to determine any effects of the Sea Empress oil spill on the plankton communities of the southern Irish Sea. The Continuous Plankton Recorder (CPR) survey has monitored the plankton in this area since 1970 so there is a long time series of data collected before the spill, almost 2000 samples, with which to compare the post-spill data. The analytical procedures applied and results obtained are presented and reveal that in the majority of cases no significant effects were evident. Some exceptions are also described. The results suggest that no further analysis of the plankton communities is necessary, unless other studies reveal that other marine habitats which may have an influence on the plankton of this area are continuing to display effects of the spill. There is scope for further investigation of the trends and events described in this report but this is outside the remit of the project. (author)

  11. Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

    KAUST Repository

    Mesa, Elena

    2017-04-21

    Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring and summer. Here we demonstrate that plankton community respiration evaluated under the continuous daylight conditions present in situ, tends to be higher than that evaluated in the dark. The ratio between community respiration measured in the light (Rlight) and in the dark (Rdark) increased as the 2/3 power of Rlight so that the Rlight:Rdark ratio increased from an average value of 1.37 at the median Rlight measured here (3.62 µmol O2 L-1 d-1) to an average value of 17.56 at the highest Rlight measured here (15.8 µmol O2 L-1 d-1). The role of respiratory processes as a source of CO2 in the Arctic has, therefore, been underestimated and is far more important than previously believed, particularly in the late spring, with 24 h photoperiods, when community respiration rates are highest.

  12. Comparative study on composition and abundance of major planktons and physico-chemical characteristics among two ponds and Lake Tana, Ethiopia

    Directory of Open Access Journals (Sweden)

    Wondie Zelalem Amanu

    2015-11-01

    Full Text Available Objective: To evaluate the difference in physico-chemical characteristics, composition and abundance of plankton communities owing to the supplementary feed added in fish ponds as compared to Lake Tana. Methods: Physico-chemical and biological data of plankton were collected from 3 studied sites from November 2008 to October 2009. Data were compared using One-way ANOVA to see the difference among sites. Diversity indices such as Margalef's index, Shannon-Wiener index, and evenness index were employed to describe the distribution of plankton community among the studied sites. Results: The pH value was remarkably higher in ponds water. However, conductivity and total dissolved solids were the highest in lake water. Nitrate concentration was relatively high in ponds. Zooplankton species richness was higher in lake water than ponds. The lake also had the highest mean value of both Shannon-Wiener index and evenness index in phytoplankton. Conclusions: The results revealed that the supplementary feed added to each pond had influence on nutrient content which enhanced algal biomass and productivity of the ponds. However, the pond water has to be regularly refreshed to control eutrophication.

  13. Relative invasion risk for plankton across marine and freshwater systems: examining efficacy of proposed international ballast water discharge standards.

    Directory of Open Access Journals (Sweden)

    Oscar Casas-Monroy

    Full Text Available Understanding the implications of different management strategies is necessary to identify best conservation trajectories for ecosystems exposed to anthropogenic stressors. For example, science-based risk assessments at large scales are needed to understand efficacy of different vector management approaches aimed at preventing biological invasions associated with commercial shipping. We conducted a landscape-scale analysis to examine the relative invasion risk of ballast water discharges among different shipping pathways (e.g., Transoceanic, Coastal or Domestic, ecosystems (e.g., freshwater, brackish and marine, and timescales (annual and per discharge event under current and future management regimes. The arrival and survival potential of nonindigenous species (NIS was estimated based on directional shipping networks and their associated propagule pressure, environmental similarity between donor-recipient ecosystems (based on salinity and temperature, and effects of current and future management strategies (i.e., ballast water exchange and treatment to meet proposed international biological discharge standards. Our findings show that current requirements for ballast water exchange effectively reduce invasion risk to freshwater ecosystems but are less protective of marine ecosystems because of greater environmental mismatch between source (oceanic and recipient (freshwater ecoregions. Future requirements for ballast water treatment are expected to reduce risk of zooplankton NIS introductions across ecosystem types but are expected to be less effective in reducing risk of phytoplankton NIS. This large-scale risk assessment across heterogeneous ecosystems represents a major step towards understanding the likelihood of invasion in relation to shipping networks, the relative efficacy of different invasion management regimes and seizing opportunities to reduce the ecological and economic implications of biological invasions.

  14. Planktonic benthonic foraminiferal ratios: Modern patterns and Tertiary applicability

    Science.gov (United States)

    Gibson, T.G.

    1989-01-01

    The abundance of planktonic specimens in foraminiferal assemblages was determined in numerous bottom samples from inner neritic to deep oceanic depths along the Atlantic margin of the northeastern United States. The results augment previous studies in other areas that have shown a general increase in percentage of planktonic specimens in total foraminiferal bottom assemblages as water depth increases. The patterns found in this area of complex shelf bathymetry and hydrography illustrate the influence on the planktonic-benthonic percentages of water depth, distance from shore, different water mass properties and downslope movement of tests in high energy areas. The patterns found in the 661 samples from the Atlantic margin were compared with results from 795 stations in the Gulf of Mexico, Pacific Ocean and Red Sea. The relative abundance of planktonic specimens and water depth correlates positively in all open oceanic areas even though taxonomic composition and diversity of the faunas from different areas is variable. The variation of planktonic percentages in bottom samples within most depth intervals is large so that a precise depth determination cannot be made for any given value. However, an approximate upper depth limit for given percentages can be estimated for open ocean environments. A decrease in planktonic percentages is seen in the lower salinity and higher turbidity coastal waters of the Gulf of Maine. Planktonic percentages intermediate between the lower values in the less saline coastal waters and the higher values in the normal open oceanic conditions occur in the transitional area between the Gulf of Maine and the open marine Atlantic Ocean to the east. Similarly lowered values in another area of restricted oceanic circulation occur in the high salinity, clear, but nutrient-poor waters of the Gulf of Aqaba off the Red Sea. A comparison of the similarity of modern planktonic percentage values to those found in earlier Tertiary assemblages was made to

  15. A comparative phylogenetic analysis of full-length mariner elements

    Indian Academy of Sciences (India)

    Mariner like elements (MLEs) are widely distributed type II transposons with an open reading frame (ORF) for transposase. We studied comparative phylogenetic evolution and inverted terminal repeat (ITR) conservation of MLEs from Indian saturniid silkmoth, Antheraea mylitta with other full length MLEs submitted in the ...

  16. Detection of biofilm production of Yersinia enterocolitica strains isolated from infected children and comparative antimicrobial susceptibility of biofilm versus planktonic forms.

    Science.gov (United States)

    Ioannidis, A; Kyratsa, A; Ioannidou, V; Bersimis, S; Chatzipanagiotou, S

    2014-06-01

    The ability of Yersinia species to produce biofilms has not been hitherto systematically studied, although there is evidence, that Y. enterocolitica is able to form biofilms on inanimate surfaces. The present study aimed to detect the production of biofilms by 60 clinical strains of Y. enterocolitica and to compare the antimicrobial susceptibility of planktonic versus biofilm-forming bacteria. Y. enterocolitica strains were collected from stool and blood cultures collected from β-thalassaemic children, with gastroenteritis and/or septicemia. The isolated bacterial strains were grouped by biotyping and serotyping and the antimicrobial susceptibility of the planktonic forms was investigated by MIC determination. Biofilm formation was detected by the use of silicone disks and for the biofilm forming strains the minimum inhibitory concentration for bacterial regrowth (MICBR) of 11 clinically important antimicrobials was determined. The presence of the waaE, a gene reported to be related with biofilm formation was investigated in all the strains. All of 60 strains were positive for biofilm production by the use of silicone disks. The great majority of the biofilm forms were resistant to all the antimicrobials. In antimicrobial concentrations far higher than the CLSI breakpoints, bacterial regrowth from the biofilms was still possible. None of the strains bore the waaE gene. These results, indicate that biofilm formation by Y. enterocolitica might be an inherent feature. The presence of biofilms increased dramatically the MICBR in all antimicrobials. The way in which biofilms could contribute to Y. enterocolitica pathogenicity in humans is a matter needing further investigation.

  17. Gelatinous plankton is central to the diet of European eel (Anguilla anguilla) larvae in the Sargasso Sea

    DEFF Research Database (Denmark)

    Ayala, Daniel Jiro; Munk, Peter; Lundgreen, Regitze B. C.

    2018-01-01

    endangered species. Next-generation 18S rRNA gene sequencing data of Sargasso Sea eel larvae gut contents and marine snow aggregates was compared with a reference plankton database to assess the trophic relations of eel larvae. Gut contents of A. anguilla larvae were not well explained by the eukaryotic...

  18. Comprehensive model of annual plankton succession based on the whole-plankton time series approach.

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Romagnan

    Full Text Available Ecological succession provides a widely accepted description of seasonal changes in phytoplankton and mesozooplankton assemblages in the natural environment, but concurrent changes in smaller (i.e. microbes and larger (i.e. macroplankton organisms are not included in the model because plankton ranging from bacteria to jellies are seldom sampled and analyzed simultaneously. Here we studied, for the first time in the aquatic literature, the succession of marine plankton in the whole-plankton assemblage that spanned 5 orders of magnitude in size from microbes to macroplankton predators (not including fish or fish larvae, for which no consistent data were available. Samples were collected in the northwestern Mediterranean Sea (Bay of Villefranche weekly during 10 months. Simultaneously collected samples were analyzed by flow cytometry, inverse microscopy, FlowCam, and ZooScan. The whole-plankton assemblage underwent sharp reorganizations that corresponded to bottom-up events of vertical mixing in the water-column, and its development was top-down controlled by large gelatinous filter feeders and predators. Based on the results provided by our novel whole-plankton assemblage approach, we propose a new comprehensive conceptual model of the annual plankton succession (i.e. whole plankton model characterized by both stepwise stacking of four broad trophic communities from early spring through summer, which is a new concept, and progressive replacement of ecological plankton categories within the different trophic communities, as recognised traditionally.

  19. Plankton biodiversity of Dharamtar creek adjoining Mumbai harbour

    Digital Repository Service at National Institute of Oceanography (India)

    Tiwari, L.R.; Nair, V.R.

    rich plankton community. However, recent industrial development along the banks of creek may pose the problem due to waste disposal into this creek system. Losses of marine life diversity are largely the results of conflicting uses, in particular...

  20. Modelling emergent trophic strategies in plankton

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Aksnes, Dag L.; Berge, Terje

    2015-01-01

    Plankton are typically divided into phytoplankton and zooplankton in marine ecosystem models. Yet, most protists in the photic zone engage in some degree of phagotrophy, and it has been suggested that trophic strategy is really a continuum between pure phototrophs (phytoplankton) and pure...

  1. Marine snow, zooplankton and thin layers: indications of a trophic link from small-scale sampling with the Video Plankton Recorder

    DEFF Research Database (Denmark)

    Möller, Klas O.; St. John, Michael; Temming, Axel

    2012-01-01

    Marine aggregates of biogenic origin, known as marine snow, are considered to play a major role in the ocean’s particle flux and may represent a concentrated food source for zooplankton. However, observing the marine snow−zooplankton interaction in the field is difficult since conventional net sa...... to aggregates and demonstrating feeding behaviour, which also suggests a trophic interaction. Our observations highlight the potential significance of marine snow in marine ecosystems and its potential as a food resource for various trophic levels, from bacteria up to fish...

  2. Unraveling the intricate dynamics of planktonic Arctic marine food webs. A sensitivity analysis of a well-documented food web model

    Science.gov (United States)

    Saint-Béat, Blanche; Maps, Frédéric; Babin, Marcel

    2018-01-01

    The extreme and variable environment shapes the functioning of Arctic ecosystems and the life cycles of its species. This delicate balance is now threatened by the unprecedented pace and magnitude of global climate change and anthropogenic pressure. Understanding the long-term consequences of these changes remains an elusive, yet pressing, goal. Our work was specifically aimed at identifying which biological processes impact Arctic planktonic ecosystem functioning, and how. Ecological Network Analysis (ENA) indices reveal emergent ecosystem properties that are not accessible through simple in situ observation. These indices are based on the architecture of carbon flows within food webs. But, despite the recent increase in in situ measurements from Arctic seas, many flow values remain unknown. Linear inverse modeling (LIM) allows missing flow values to be estimated from existing flow observations and, subsequent reconstruction of ecosystem food webs. Through a sensitivity analysis on a LIM model of the Amundsen Gulf in the Canadian Arctic, we were able to determine which processes affected the emergent properties of the planktonic ecosystem. The analysis highlighted the importance of an accurate knowledge of the various processes controlling bacterial production (e.g. bacterial growth efficiency and viral lysis). More importantly, a change in the fate of the microzooplankton within the food web can be monitored through the trophic level of mesozooplankton. It can be used as a "canary in the coal mine" signal, a forewarner of larger ecosystem change.

  3. The predictive skill of species distribution models for plankton in a changing climate

    DEFF Research Database (Denmark)

    Brun, Philipp Georg; Kiørboe, Thomas; Licandro, Priscilla

    2016-01-01

    Statistical species distribution models (SDMs) are increasingly used to project spatial relocations of marine taxa under future climate change scenarios. However, tests of their predictive skill in the real-world are rare. Here, we use data from the Continuous Plankton Recorder program, one...... null models, is essential to assess the robustness of projections of marine planktonic species under climate change...

  4. Gelatinous plankton is central to the diet of European eel (Anguilla anguilla) larvae in the Sargasso Sea

    DEFF Research Database (Denmark)

    Ayala, Daniel Jiro; Munk, Peter; Lundgreen, Regitze B. C.

    2018-01-01

    endangered species. Next-generation 18S rRNA gene sequencing data of Sargasso Sea eel larvae gut contents and marine snow aggregates was compared with a reference plankton database to assess the trophic relations of eel larvae. Gut contents of A. anguilla larvae were not well explained by the eukaryotic...... composition of marine snow aggregates; gut contents being dominated by gene sequences of Hydrozoa taxa (phylum Cnidaria), while snow aggregates were dominated by Crustacea taxa. Pronounced differences between gut contents and marine snow aggregates were also seen in the prokaryotic 16S rRNA gene composition...

  5. Research highlights: impacts of microplastics on plankton.

    Science.gov (United States)

    Lin, Vivian S

    2016-02-01

    Each year, millions of metric tons of the plastic produced for food packaging, personal care products, fishing gear, and other human activities end up in lakes, rivers, and the ocean. The breakdown of these primary plastics in the environment results in microplastics, small fragments of plastic typically less than 1-5 mm in size. These synthetic particles have been detected in all of the world's oceans and also in many freshwater systems, accumulating in sediment, on shorelines, suspended in surface waters, and being ingested by plankton, fish, birds, and marine mammals. While the occurrence of plastics in surface waters has been surveyed in a number of studies, the impacts of microplastics on marine organisms are still being elucidated. This highlight features three recent publications that explore the interactions of microplastics with planktonic organisms to clarify the effects of these pollutants on some of the ocean's smallest and most important inhabitants.

  6. Habitat suitability and ecological niches of different plankton functional types in the global ocean

    Science.gov (United States)

    Vogt, Meike; Brun, Philipp; Payne, Mark R.; O'Brien, Colleen J.; Bednaršek, Nina; Buitenhuis, Erik T.; Doney, Scott C.; Leblanc, Karine; Le Quéré, Corinne; Luo, Yawei; Moriarty, Róisín; O'Brien, Todd D.; Schiebel, Ralf; Swan, Chantal

    2013-04-01

    Marine plankton play a central role in the biogeochemical cycling of important elements such as carbon, nitrogen, and sulphur. While our knowledge about marine ecosystem structure and functioning is still scarce and episodic, several recent observational studies confirm that marine ecosystems have been changing due to recent climate change, overfishing, and coastal eutrophication. In order to better understand marine ecosystem dynamics, the MAREDAT initiative has recently collected abundance and biomass data for 5 autotrophic (diatoms, Phaeocystis, coccolithophores, nitrogen fixers, picophytoplankton), and 6 heterotrophic plankton functional types (PFTs; bacteria, micro-, meso- and macrozooplankton, foraminifera and pteropods). Species distribution models (SDMs) are statistical tools that can be used to derive information about species habitats in space and time. They have been used extensively for a wide range of ecological applications in terrestrial ecosystems, but here we present the first global application in the marine realm, which was made possible by the MAREDAT data synthesis effort. We use a maximum entropy SDM to simulate global habitat suitability, habitat extent and ecological niches for different PFTs in the modern ocean. Present habitat suitability is derived from presence-only MAREDAT data and the observed annual and monthly mean levels of physiologically relevant variables such as SST, nutrient concentration or photosynthetic active radiation received in the mixed layer. This information can then be used to derive ecological niches for different species or taxa within each PFT, and to compare the ecological niches of different PFTs. While these results still need verification because data was not available for all ocean regions for all PFTs, they can give a first indication what present and future plankton habitats may look like, and what consequences we may have to expect for future marine ecosystem functioning and service provision in a warmer

  7. Planktonic Crustacean Culture - Live Planktonic Crustaceans as Live Feed for Finfish and Shrimps in Aquaculture

    DEFF Research Database (Denmark)

    Jepsen, Per Meyer; Syberg, Kristian; Drillet, Guillaume

    2018-01-01

    The cultivation of planktonic crustaceans as live feed is of paramount importance for the aquaculture and aquarium industries. The use of live cladocerans as feed for freshwater fish is limited to the aquarium industry, whereas Artemia and copepods are used to feed edible marine fish larvae...... assessments for hazardous chemicals. Cladocerans are widely used for ecotoxicology testing but Artemia and copepods are emerging new model species. In the present chapter, we review the culturing procedures of these important planktonic crustaceans: Artemia, cladocerans and copepods and discuss their use...

  8. Computer vision for continuous plankton monitoring

    OpenAIRE

    Damian Janusz Matuszewski

    2014-01-01

    Plankton microorganisms constitute the base of the marine food web and play a great role in global atmospheric carbon dioxide drawdown. Moreover, being very sensitive to any environmental changes they allow noticing (and potentially counteracting) them faster than with any other means. As such they not only influence the fishery industry but are also frequently used to analyze changes in exploited coastal areas and the influence of these interferences on local environment and climate. As a co...

  9. A comparative life cycle assessment of marine power systems

    International Nuclear Information System (INIS)

    Ling-Chin, Janie; Roskilly, Anthony P.

    2016-01-01

    Highlights: • Correlation among resources, emissions, key components and processes was attained. • Environmental benefits of innovative power systems were verified. • New-build system showed a great advantage over retrofit and conventional systems. • Relative contribution of significant components remained or became more profound. • Influence of fuel consumption quantity over the estimates varied with impact types. - Abstract: Despite growing interest in advanced marine power systems, knowledge gaps existed as it was uncertain which configuration would be more environmentally friendly. Using a conventional system as a reference, the comparative life cycle assessment (LCA) study aimed to compare and verify the environmental benefits of advanced marine power systems i.e. retrofit and new-build systems which incorporated emerging technologies. To estimate the environmental impact attributable to each system, a bottom-up integrated system approach was applied, i.e. LCA models were developed for individual components using GaBi, optimised operational profiles and input data standardised from various sources. The LCA models were assessed using CML2001, ILCD and Eco-Indicator99 methodologies. The estimates for the advanced systems were compared to those of the reference system. The inventory analysis results showed that both retrofit and new-build systems consumed less fuels (8.28% and 29.7% respectively) and released less emissions (5.2–16.6% and 29.7–55.5% respectively) during operation whilst more resources were consumed during manufacture, dismantling and the end of life. For 14 impact categories relevant to global warming, acidification, eutrophication, photochemical ozone creation and PM/respiratory inorganic health issues, reduction in LCIA results was achieved by retrofit (2.7–6.6%) and new-build systems (35.7–50.7%). The LCIA results of the retrofit system increased in ecotoxicity (1–8%), resource depletion (1–2%) and fossil fuel depletion

  10. Is Ammonification Rate in Marine Sediment Related to Plankton Composition and Abundance? A Time-series Study in Villefranche Bay (NW Mediterranean)

    Science.gov (United States)

    Fernex, François E.; Braconnot, Jean-Claude; Dallot, Serge; Boisson, Michel

    1996-09-01

    Observations were made near Cap Ferrat (Station B, about 80 m in water depth) France, in the water column and in the sediment, in order to evaluate to what extent variations in the ammonia and nitrate concentrations of the sediments are related to plankton population abundance and composition. Nitrate, nitrite, ammonia and chlorophyll awere measured several times during 1987 to 1989, at two depths (1 and 40 m). Copepods and salps in the upper 75 m of the water column were counted several times a week from 1987 to 1990. Ammonia and nitrate concentrations and ammonification rate were determined in the underlying sediments. During Spring 1987, phytoplankton biomass showed a maximum at the end of March; copepod populations increased regularly till the end of April, and salps increased from this time to the end of May. These populations were not so well developed during Spring 1988 and 1989. During the blooms, salp were mainly represented by Thalia democratica. The biomass of phytoplankton and zooplankton was low in summer. The sequence suggests that the copepod decline was related to reduced food levels after the phytoplankton decline. Salp population growth was not at the expense of phytoplankton and it can be assumed that the salp fed on other material. In 1987 and 1988, maximum organic nitrogen concentration in the bottom sediment and maximum ammonification rate directly followed the salp spring bloom. In 1987, the highest ammonification rate measured in the surficial sediment (0-2 cm) reached 0·05 μ M cm 3day -1(in June). In 1990, the rate exceeded 0·1 μM cm -3 day -1during an important salp bloom. Therefore, it seems that the sinking of salp fecal pellets plays an important part in the transfer of organic matter to the bottom, and microbial activity in the surficial sediment leads to mineralization of a great part of the organic nitrogen quickly after its deposition.

  11. Comparing marine and terrestrial ecosystems: Implications for the design of coastal marine reserves

    Science.gov (United States)

    Carr, M.H.; Neigel, J.E.; Estes, J.A.; Andelman, S.; Warner, R.R.; Largier, J. L.

    2003-01-01

    Concepts and theory for the design and application of terrestrial reserves is based on our understanding of environmental, ecological, and evolutionary processes responsible for biological diversity and sustainability of terrestrial ecosystems and how humans have influenced these processes. How well this terrestrial-based theory can be applied toward the design and application of reserves in the coastal marine environment depends, in part, on the degree of similarity between these systems. Several marked differences in ecological and evolutionary processes exist between marine and terrestrial ecosystems as ramifications of fundamental differences in their physical environments (i.e., the relative prevalence of air and water) and contemporary patterns of human impacts. Most notably, the great extent and rate of dispersal of nutrients, materials, holoplanktonic organisms, and reproductive propagules of benthic organisms expand scales of connectivity among near-shore communities and ecosystems. Consequently, the "openness" of marine populations, communities, and ecosystems probably has marked influences on their spatial, genetic, and trophic structures and dynamics in ways experienced by only some terrestrial species. Such differences appear to be particularly significant for the kinds of organisms most exploited and targeted for protection in coastal marine ecosystems (fishes and macroinvertebrates). These and other differences imply some unique design criteria and application of reserves in the marine environment. In explaining the implications of these differences for marine reserve design and application, we identify many of the environmental and ecological processes and design criteria necessary for consideration in the development of the analytical approaches developed elsewhere in this Special Issue.

  12. Whole transcriptome analysis of Acinetobacter baumannii assessed by RNA-sequencing reveals different mRNA expression profiles in biofilm compared to planktonic cells.

    Directory of Open Access Journals (Sweden)

    Soraya Rumbo-Feal

    Full Text Available Acinetobacterbaumannii has emerged as a dangerous opportunistic pathogen, with many strains able to form biofilms and thus cause persistent infections. The aim of the present study was to use high-throughput sequencing techniques to establish complete transcriptome profiles of planktonic (free-living and sessile (biofilm forms of A. baumannii ATCC 17978 and thereby identify differences in their gene expression patterns. Collections of mRNA from planktonic (both exponential and stationary phase cultures and sessile (biofilm cells were sequenced. Six mRNA libraries were prepared following the mRNA-Seq protocols from Illumina. Reads were obtained in a HiScanSQ platform and mapped against the complete genome to describe the complete mRNA transcriptomes of planktonic and sessile cells. The results showed that the gene expression pattern of A. baumannii biofilm cells was distinct from that of planktonic cells, including 1621 genes over-expressed in biofilms relative to stationary phase cells and 55 genes expressed only in biofilms. These differences suggested important changes in amino acid and fatty acid metabolism, motility, active transport, DNA-methylation, iron acquisition, transcriptional regulation, and quorum sensing, among other processes. Disruption or deletion of five of these genes caused a significant decrease in biofilm formation ability in the corresponding mutant strains. Among the genes over-expressed in biofilm cells were those in an operon involved in quorum sensing. One of them, encoding an acyl carrier protein, was shown to be involved in biofilm formation as demonstrated by the significant decrease in biofilm formation by the corresponding knockout strain. The present work serves as a basis for future studies examining the complex network systems that regulate bacterial biofilm formation and maintenance.

  13. Radionuclides in plankton from the South Pacific Basin

    International Nuclear Information System (INIS)

    Marsh, K.V.; Buddemeier, R.W.

    1984-01-01

    An investigation has been initiated of the utility of marine plankton as bioconcentrating samplers of low-level marine radioactivity in the southern hemisphere. A literature review has shown that both freshwater and marine plankton have trace element and radionuclide concentration factors (relative to water) of up to 10 4 . In 1956 and 1958 considerable work was done on the accumulation and distribution of a variety of fission and activation products produced by nuclear tests in the Marshall Islands. Since then, studies, have largely been confined to a few radionuclides, and most of the work in the last twenty years has been done in the northern hemisphere. The authors participated in Operations Deepfreeze 1981 and 1982, collecting a total of 48 plankton samples from the USCGC Glacier on its Antarctic cruises. Battelle Pacific Northwest Laboratories sampled air, water, rain, and fallout. The authors were able to measure concentrations in plankton of the naturally-occurring radionuclides 7 Be, 40 K, and the U and Th series, and they believe that they have detected low levels of 144 Ce and 95 Nb in seven samples ranging as far south as 68 0 . Biological identification of the plankton suggests a possible correlation between radionuclide concentration and the protozoa content of the samples. 7 references, 5 figures, 1 table

  14. Public aquaria as long-term enrichments for investigating planktonic Archaea

    Science.gov (United States)

    Goldenstein, Nadine I.; Warren, Courtney E.; Lipp, Julius S.; Pagani, Mark; Hinrichs, Kai-Uwe

    2016-04-01

    The most abundant group of planktonic Archaea , the so-called Thaumarchaeota, represents 20% of all marine planktonic microorganisms (Karner et al., 2001) and their energy efficient performance of nitrification makes them key players in the global nitrogen- and carbon-cycle (Könneke et al., 2014). Furthermore, planktonic Archaea are considered to be the major producers of specific microbial membrane lipids that are extensively used as paleoproxies in marine climate research (Schouten et al., 2002). Therefore, assessing the parameters controlling the distribution of Archaea in the marine water column is crucial for studies of modern and past marine environments. Although diverse studies utilizing DNA- and biomarker-based approaches have constrained the turnover and distribution of marine Archaea, the environmental factors affecting their abundance and activity (e.g., Wuchter et al., 2006; Bale et al., 2013) are still poorly understood. Further, previous surveys, using enrichment cultivation and pure culture experiments, provided valuable information on adaptation of planktonic Archaea to changes of parameters affecting growth conditions, such as temperature, salinity and growth stage (Elling et al., 2014, 2015). Hence, we know that planktonic Archaea directly adapt their membranes to changing growth conditions, but also that environmental selection for individual phylogenetic groups of these organisms is also reflected in the membrane lipid pool. Extending these studies, this project further aims at constraining the environmental parameters controlling archaeal abundance in the marine environment. Public aquaria, which are comparable to perfectly monitored long-term enrichment cultures, are optimal sampling sites for this task. A comprehensive set of 120 water and substrate samples from fresh, marine and brackish systems exhibiting diverse conditions was selected from 15 public aquaria at the east and west coast of the USA. These samples were examined for their

  15. Erythrocyte levels compared with reported dietary intake of marine n-3 fatty acids in pregnant women

    DEFF Research Database (Denmark)

    Olsen, S.F.; Hansen, H.S.; Sandstrom, B.

    1995-01-01

    It is well established that marine n-3 fatty acids measured in erythrocyte phospholipids of non-pregnant subjects reflect the subjects' intake of these fatty acids. In 135 pregnant women in the 30th week of gestation we compared intake of marine n-3 fatty acids and energy, estimated by a combined...... dietary self- administered questionnaire and interview, with fatty acids measured in erythrocyte phospholipids. Daily intake (g/d) and nutrient density of marine n-3 fatty acids (mg/MJ) correlated with the n-3 fatty acid: arachidonic acid ratio (FA-ratio) with correlation coefficients of 0.48 and 0.......54 respectively. In a linear regression model with three frequency questions about marine sandwiches, marine cooked meals and fish oil as explanatory variables, and the FA-ratio as dependent variable, the multiple correlation coefficient was 0.46. Conclusions from the study were (1) levels of erythrocyte fatty...

  16. Erythrocyte levels compared with reported dietary intake of marine n-3 fatty acids in pregnant women

    DEFF Research Database (Denmark)

    Olsen, S.F.; Hansen, Harald S.; Sandstrom, B.

    1995-01-01

    It is web established that marine n-3 fatty acids measured in erythrocyte phospholipids of non-pregnant subjects reflect the subjects' intake of these fatty acids. In 135 pregnant women in the 30th week of gestation we compared intake of marine n-3 fatty acids and energy, estimated by a combined...... dietary self-administered questionnaire and interview, with fatty acids measured in erythrocyte phospholipids. Daily intake (g/d) and nutrient density of marine n-3 fatty acids (mg/MJ) correlated with the n-3 fatty acid: arachidonic acid ratio (FA-ratio) with correlation coefficients of 0.48 and 0.......54 respectively. In a linear regression model with three frequency questions about marine sandwiches, marine cooked meals and fish oil as explanatory variables, and the FA-ratio as dependent variable, the multiple correlation coefficient was 0.46. Conclusions from the study were (1) levels of erythrocyte fatty...

  17. Een methode ter bepaling van de respiratieaktiviteit in marien plankton

    NARCIS (Netherlands)

    Lambeck, R.H.D.

    1973-01-01

    The usefulness of a method, described by T.T. Packard (1971), for the determination of the potential respiratory rate in marine plankton, based on the use of tetrazolium dye, was tested. Especially the influence of a few aspects of the homogenisation procedure on the final results was investigated.

  18. Kelimpahan dan Keanekaragaman Plankton di Perairan Selat Bali (Plankton Abundance and Diversity in the Bali Strait

    Directory of Open Access Journals (Sweden)

    Ruly Isfatul Khasanah

    2013-12-01

    transitional season in November 2012 and the west season in February 2013. This research was done to observe the differences in the abundance and diversity of plankton in the two monsoon seasons. Water sample and plankton sample were collected simultaneously at the same location. Water samples were taken using a water sampler, while plankton were taken by using a planktonnet with mesh size 20 μm. Samples were taken vertically and horizontally at a depth of 1 m and 20 m below the surface. The result of nutrient measurement at Bali Strait during transitional II season showed that the concentration of phosphate, nitrate, organic matter, sillica and chlorofill-a are higher than during west season. This result indicates that there is probably movement of water mass from deeper water column to shallower area. Phosphate and nitrate are required by phytoplankton to maintain their cell membrane and sillica are used to form cell wall, especially for diatom. The reasearch also revealed that diatom (Bacillariophyceae are 95,9 % of total species and abundance of phytoplankton, and the rest are Dinophyceae. It was found that highest abundance occur during transitional season was Rhizosolenia stolterfothii of 51.405 sel.L-1 (80,1 %. While during the west monsoon the Copepod had dominates at 8.178 cell.L-1 (88,3 %. These results indicate that with plankton abundance the Bali Strait has the potential to support pelagic marine life. Keywords: plankton, Bali strait, rhizosolenia stolterfothii, monsoon

  19. Microbial eukaryote plankton communities of high-mountain lakes from three continents exhibit strong biogeographic patterns.

    Science.gov (United States)

    Filker, Sabine; Sommaruga, Ruben; Vila, Irma; Stoeck, Thorsten

    2016-05-01

    Microbial eukaryotes hold a key role in aquatic ecosystem functioning. Yet, their diversity in freshwater lakes, particularly in high-mountain lakes, is relatively unknown compared with the marine environment. Low nutrient availability, low water temperature and high ultraviolet radiation make most high-mountain lakes extremely challenging habitats for life and require specific molecular and physiological adaptations. We therefore expected that these ecosystems support a plankton diversity that differs notably from other freshwater lakes. In addition, we hypothesized that the communities under study exhibit geographic structuring. Our rationale was that geographic dispersal of small-sized eukaryotes in high-mountain lakes over continental distances seems difficult. We analysed hypervariable V4 fragments of the SSU rRNA gene to compare the genetic microbial eukaryote diversity in high-mountain lakes located in the European Alps, the Chilean Altiplano and the Ethiopian Bale Mountains. Microbial eukaryotes were not globally distributed corroborating patterns found for bacteria, multicellular animals and plants. Instead, the plankton community composition emerged as a highly specific fingerprint of a geographic region even on higher taxonomic levels. The intraregional heterogeneity of the investigated lakes was mirrored in shifts in microbial eukaryote community structure, which, however, was much less pronounced compared with interregional beta-diversity. Statistical analyses revealed that on a regional scale, environmental factors are strong predictors for plankton community structures in high-mountain lakes. While on long-distance scales (>10 000 km), isolation by distance is the most plausible scenario, on intermediate scales (up to 6000 km), both contemporary environmental factors and historical contingencies interact to shift plankton community structures. © 2016 John Wiley & Sons Ltd.

  20. Ecological partitioning and diversity in tropical planktonic foraminifera

    Directory of Open Access Journals (Sweden)

    Seears Heidi A

    2012-04-01

    Full Text Available Abstract Background Ecological processes are increasingly being viewed as an important mode of diversification in the marine environment, where the high dispersal potential of pelagic organisms, and a lack of absolute barriers to gene flow may limit the occurrence of allopatric speciation through vicariance. Here we focus on the potential role of ecological partitioning in the diversification of a widely distributed group of marine protists, the planktonic foraminifera. Sampling was conducted in the tropical Arabian Sea, during the southwest (summer monsoon, when pronounced environmental conditions result in a strong disparity in temperature, salinity and productivity between distinct northern and southern water masses. Results We uncovered extensive genetic diversity within the Arabian Sea planktonic foraminifera, identifying 13 morphospecies, represented by 20 distinct SSU rRNA genetic types. Several morphospecies/genetic types displayed non-random biogeographical distributions, partitioning between the northern and southern water masses, giving a strong indication of independent ecological adaptations. Conclusions We propose sea-surface primary productivity as the main factor driving the geographical segregation of Arabian Sea planktonic foraminifera, during the SW monsoon, with variations in symbiotic associations possibly playing a role in the specific ecological adaptations observed. Our findings suggest that ecological partitioning could be contributing to the high levels of 'cryptic' genetic diversity observed within the planktonic foraminifera, and support the view that ecological processes may play a key role in the diversification of marine pelagic organisms.

  1. Design and calibration of a new optical plankton counter capable of sizing small zooplankton

    Science.gov (United States)

    Herman, Alex W.

    1992-04-01

    A new design of optical plankton counter (OPC) capable of sizing zooplankton in the size range of 256μ to 2 cm is presented. The detection sensitivity is the result of new optical design of the previous system ( HERMAN, 1988, Continental Shelf Research, 8, 205-221) that originally had a lower detection limit of 550 μm. Both theoretical and experimental calibrations for the OPC are derived and compared. Preserved copepods and eggs introduced in a flow tank demonstrate the response of the OPC and its capability for detecting plankton to a limit of 250 μm. Copepod profiles measured by the OPC mounted on plankton net samplers provided intercomparisons that showed good agreement in identifying copepod layers and identifying some species, for example, copepods as small as Calanus finmarchicus II and up to the adult stages. Profiles containing marine snow and Ceratium illustrate some of the limitations of the OPC in directly measuring and identifying copepods. An additional modification to the OPC may result in a potential lower limit detection of 120 μm, and the practicality of such applications are discussed.

  2. Responses of marine plankton to pollutant stress

    DEFF Research Database (Denmark)

    Hjorth, M.

    to reveal indirect effects and co-effects with the abiotic environment on three trophic levels, namely bacteria, phytoplankton and zooplankton. The role of mesocosms and community studies in risk assessment and their usefulness in integrating ecological knowledge into ecotoxicology is discussed...... with examples of work done on natural communities of phytoplankton and zooplankton. Abiotic conditions such as UV light and nutrient concentrations are shown to influence pollutant effects....

  3. Identification of major planktonic sulfur oxidizers in stratified freshwater lake.

    Directory of Open Access Journals (Sweden)

    Hisaya Kojima

    Full Text Available Planktonic sulfur oxidizers are important constituents of ecosystems in stratified water bodies, and contribute to sulfide detoxification. In contrast to marine environments, taxonomic identities of major planktonic sulfur oxidizers in freshwater lakes still remain largely unknown. Bacterioplankton community structure was analyzed in a stratified freshwater lake, Lake Mizugaki in Japan. In the clone libraries of 16S rRNA gene, clones very closely related to a sulfur oxidizer isolated from this lake, Sulfuritalea hydrogenivorans, were detected in deep anoxic water, and occupied up to 12.5% in each library of different water depth. Assemblages of planktonic sulfur oxidizers were specifically analyzed by constructing clone libraries of genes involved in sulfur oxidation, aprA, dsrA, soxB and sqr. In the libraries, clones related to betaproteobacteria were detected with high frequencies, including the close relatives of Sulfuritalea hydrogenivorans.

  4. Regime shifts in demersal assemblages of the Benguela Current Large Marine Ecosystem: a comparative assessment

    DEFF Research Database (Denmark)

    Kirkman, Stephen P.; Yemane, Dawit; Atkinson, Lara J.

    2015-01-01

    Using long‐term survey data, changes in demersal faunal communities in the Benguela Current Large Marine Ecosystem were analysed at community and population levels to provide a comparative overview of the occurrence and timing of regime shifts. For South Africa, the timing of a community‐level sh......Using long‐term survey data, changes in demersal faunal communities in the Benguela Current Large Marine Ecosystem were analysed at community and population levels to provide a comparative overview of the occurrence and timing of regime shifts. For South Africa, the timing of a community...

  5. Estimating planktonic diversity through spatial dominance patterns in a model ocean.

    Science.gov (United States)

    Soccodato, Alice; d'Ovidio, Francesco; Lévy, Marina; Jahn, Oliver; Follows, Michael J; De Monte, Silvia

    2016-10-01

    In the open ocean, the observation and quantification of biodiversity patterns is challenging. Marine ecosystems are indeed largely composed by microbial planktonic communities whose niches are affected by highly dynamical physico-chemical conditions, and whose observation requires advanced methods for morphological and molecular classification. Optical remote sensing offers an appealing complement to these in-situ techniques. Global-scale coverage at high spatiotemporal resolution is however achieved at the cost of restrained information on the local assemblage. Here, we use a coupled physical and ecological model ocean simulation to explore one possible metrics for comparing measures performed on such different scales. We show that a large part of the local diversity of the virtual plankton ecosystem - corresponding to what accessible by genomic methods - can be inferred from crude, but spatially extended, information - as conveyed by remote sensing. Shannon diversity of the local community is indeed highly correlated to a 'seascape' index, which quantifies the surrounding spatial heterogeneity of the most abundant functional group. The error implied in drastically reducing the resolution of the plankton community is shown to be smaller in frontal regions as well as in regions of intermediate turbulent energy. On the spatial scale of hundreds of kms, patterns of virtual plankton diversity are thus largely sustained by mixing communities that occupy adjacent niches. We provide a proof of principle that in the open ocean information on spatial variability of communities can compensate for limited local knowledge, suggesting the possibility of integrating in-situ and satellite observations to monitor biodiversity distribution at the global scale. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Large-scale ocean connectivity and planktonic body size

    KAUST Repository

    Villarino, Ernesto

    2018-01-04

    Global patterns of planktonic diversity are mainly determined by the dispersal of propagules with ocean currents. However, the role that abundance and body size play in determining spatial patterns of diversity remains unclear. Here we analyse spatial community structure - β-diversity - for several planktonic and nektonic organisms from prokaryotes to small mesopelagic fishes collected during the Malaspina 2010 Expedition. β-diversity was compared to surface ocean transit times derived from a global circulation model, revealing a significant negative relationship that is stronger than environmental differences. Estimated dispersal scales for different groups show a negative correlation with body size, where less abundant large-bodied communities have significantly shorter dispersal scales and larger species spatial turnover rates than more abundant small-bodied plankton. Our results confirm that the dispersal scale of planktonic and micro-nektonic organisms is determined by local abundance, which scales with body size, ultimately setting global spatial patterns of diversity.

  7. Large-scale ocean connectivity and planktonic body size

    KAUST Repository

    Villarino, Ernesto; Watson, James R.; Jö nsson, Bror; Gasol, Josep M.; Salazar, Guillem; Acinas, Silvia G.; Estrada, Marta; Massana, Ramó n; Logares, Ramiro; Giner, Caterina R.; Pernice, Massimo C.; Olivar, M. Pilar; Citores, Leire; Corell, Jon; Rodrí guez-Ezpeleta, Naiara; Acuñ a, José Luis; Molina-Ramí rez, Axayacatl; Gonzá lez-Gordillo, J. Ignacio; Có zar, André s; Martí , Elisa; Cuesta, José A.; Agusti, Susana; Fraile-Nuez, Eugenio; Duarte, Carlos M.; Irigoien, Xabier; Chust, Guillem

    2018-01-01

    Global patterns of planktonic diversity are mainly determined by the dispersal of propagules with ocean currents. However, the role that abundance and body size play in determining spatial patterns of diversity remains unclear. Here we analyse spatial community structure - β-diversity - for several planktonic and nektonic organisms from prokaryotes to small mesopelagic fishes collected during the Malaspina 2010 Expedition. β-diversity was compared to surface ocean transit times derived from a global circulation model, revealing a significant negative relationship that is stronger than environmental differences. Estimated dispersal scales for different groups show a negative correlation with body size, where less abundant large-bodied communities have significantly shorter dispersal scales and larger species spatial turnover rates than more abundant small-bodied plankton. Our results confirm that the dispersal scale of planktonic and micro-nektonic organisms is determined by local abundance, which scales with body size, ultimately setting global spatial patterns of diversity.

  8. Comparative toxicological effects of two antifouling biocides on the marine diatom Chaetoceros lorenzianus: Damage and post-exposure recovery.

    Science.gov (United States)

    Chavan, Pooja; Kumar, Rajesh; Kirubagaran, Ramalingam; Venugopalan, Vayalam P

    2017-10-01

    Antifouling biocides are commonly used in coastal electric power stations to prevent biofouling in their condenser cooling systems. However, the environmental impact of the chemical biocides is less understood than the thermal stress effects caused by the condenser effluents. In this study, Chaetoceros lorenzianus, a representative marine diatom, was used to analyse the toxicity of two antifouling biocides, chlorine and chlorine dioxide. The diatom cells were subjected to a range of concentrations of the biocides (from 0.05 to 2mg/L, as total residual oxidants, TRO) for contact time of 30min. They were analysed for viability, genotoxicity, chlorophyll a and cell density endpoints. The cells were affected at all concentrations of the biocides (0.05-2mg/L), showing dose-dependent decrease in viability and increase in DNA damage. The treated cells were later incubated in filtered seawater devoid of biocide to check for recovery. The cells were able to recover in terms of overall viability and DNA damage, when they had been initially treated with low concentrations of the biocides (0.5mg/L of Cl 2 or 0.2mg/L of ClO 2 ). Chlorophyll a analysis showed irreparable damage at all concentrations, while cell density showed increasing trend of reduction, if treated above 0.5mg/L of Cl 2 and 0.2mg/L of ClO 2 . The data indicated that in C. lorenzianus, cumulative toxic effects and recovery potential of ClO 2 up to 0.2mg/L were comparable with those of Cl 2 , up to 0.5mg/L concentration in terms of the studied endpoints. The results indicate that at the biocide levels currently being used at power stations, recovery of the organism is feasible upon return to ambient environment. Similar studies should be carried out on other planktonic and benthic organisms, which will be helpful in the formulation of future guidelines for discharge of upcoming antifouling biocides such as chlorine dioxide. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. The structure and evolution of plankton communities

    Science.gov (United States)

    Longhurst, Alan R.

    New understanding of the circulation of ancient oceans is not yet matched by progress in our understanding of their pelagic ecology, though it was the planktonic ecosystems that generated our offshore oil and gas reserves. Can we assume that present-day models of ecosystem function are also valid for ancient seas? This question is addressed by a study of over 4000 plankton samples to derive a comprehensive, global description of zooplankton community structure in modern oceans: this shows that copepods form only 50% of the biomass of all plankton, ranging from 70% in polar to 35% in tropical seas. Comparable figures are derived from 14 other taxonomic categories of zooplankton. For trophic groupings, the data indicate globally: geletinous predators - 14%; gelatinous herbivores - 4%; raptorial predators - 33%; macrofiltering herbivores - 20%; macrofiltering omnivores - 25%; and detritivores - 3%. A simple, idealized model for the modern pelagic ecosystem is derived from these percentages which indicates that metazooplankton are not the most important consumers of pico- and nano-plankton production which itself probably constitutes 90% of primary production in warm oceans. This model is then compared with candidate life-forms available in Palaeozoic and Mesozoic oceans to determine to what extent it is also valid for ancient ecosystems: it is concluded that it is probably unnecessary to postulate models fundamentally differing from it in order to accommodate the life-forms, both protozoic and metazoic, known to have populated ancient seas. Remarkably few life-forms have existed which cannot be paralleled in the modern ocean, which contains remarkably few life-forms which cannot be paralleled in the Palaeozoic ocean. As a first assumption, then, it is reasonable to assume that energy pathways were similar in ancient oceans to those we study today.

  10. Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology

    Directory of Open Access Journals (Sweden)

    R. Morard

    2017-06-01

    Full Text Available Deep-sea sediments constitute a unique archive of ocean change, fueled by a permanent rain of mineral and organic remains from the surface ocean. Until now, paleo-ecological analyses of this archive have been mostly based on information from taxa leaving fossils. In theory, environmental DNA (eDNA in the sediment has the potential to provide information on non-fossilized taxa, allowing more comprehensive interpretations of the fossil record. Yet, the process controlling the transport and deposition of eDNA onto the sediment and the extent to which it preserves the features of past oceanic biota remains unknown. Planktonic foraminifera are the ideal taxa to allow an assessment of the eDNA signal modification during deposition because their fossils are well preserved in the sediment and their morphological taxonomy is documented by DNA barcodes. Specifically, we re-analyze foraminiferal-specific metabarcodes from 31 deep-sea sediment samples, which were shown to contain a small fraction of sequences from planktonic foraminifera. We confirm that the largest portion of the metabarcode originates from benthic bottom-dwelling foraminifera, representing the in situ community, but a small portion (< 10 % of the metabarcodes can be unambiguously assigned to planktonic taxa. These organisms live exclusively in the surface ocean and the recovered barcodes thus represent an allochthonous component deposited with the rain of organic remains from the surface ocean. We take advantage of the planktonic foraminifera portion of the metabarcodes to establish to what extent the structure of the surface ocean biota is preserved in sedimentary eDNA. We show that planktonic foraminifera DNA is preserved in a range of marine sediment types, the composition of the recovered eDNA metabarcode is replicable and that both the similarity structure and the diversity pattern are preserved. Our results suggest that sedimentary eDNA could preserve the ecological structure of

  11. Comparative Toxicity of Different Crude Oils on the Cardiac Function of Marine Medaka (Oryzias melastigma Embryo

    Directory of Open Access Journals (Sweden)

    Zhendong Zhang

    2014-12-01

    Full Text Available The acute toxic effect of different crude oils (heavy crude oil and bonny light crude oil on embryos of marine medaka Oryzias melastigma was measured and evaluated by exposure to the water-accommodated fraction (WAF in the present study. The cardiac function of medaka embryos was used as target organ of ecotoxicological effect induced by oil exposure. Results showed that the developing marine medaka heart was a sensitive target organ to crude oil exposure the heavy crude oil WAF was more toxic to cardiac function of medaka embryos than bonny light cured oil one. Cardiac function of medaka embryos was clearly affected by exposure to heavy crude oil WAF after 24 hours exposure and showed a dose-dependent slowing of heart rate. Furthermore, swelled and enlarged heart morphology, lowered blood circulation and accumulation of blood cells around the heart area were found. However, the toxic effect of bonny light crude oil on cardiac function of medaka embryos was comparatively low. Statistical results showed that the cardiac function was only affected by highest bonny light crude oil WAF (9.8 mg/L exposure treatment. These findings indicated that cardiac function of marine medaka embryo was a good toxicity model for oil pollution and could be used to compare and evaluate the toxicity of different crude oils. The heart rate was an appropriate endpoint in the acute toxicity test.

  12. Initiation of a comparative metagenomic study of the Red Sea and Pacific Ocean marine microbiomes

    KAUST Repository

    Kodzius, Rimantas

    2014-03-26

    The marine microbiome is a fundamental component of the biosphere. Its bacteria are abundant and play critical roles within the ocean environment. The majority of this important group of bacteria are genetically uncharacterized. Relatively few species have been studied in the laboratory. However, by applying metagenomic analyses to marine microbial populations, genomic ‘snapshots’ may be taken and from appropriate time series experiments their dynamics established. As a key component of the CBRC Centre Research Program (2014-2020), we are initiating a comparative study of the Red Sea and North Eastern Japanese coast and bay complexes. These environments differ in physical characteristics significantly. The Red Sea exhibits consistently high salinity, temperature and insolation characteristics, whereas the Japanese waters are less saline, cooler and receive lower insolation. Here, we present initial data and analytical pipelines for Phase 1 of our collaborative research program.

  13. Initiation of a comparative metagenomic study of the Red Sea and Pacific Ocean marine microbiomes

    KAUST Repository

    Kodzius, Rimantas; Gojobori, Takashi; Bajic, Vladimir B.; Alam, Intikhab; Mineta, Katsuhiko; Watabe, Shugo; Ikeo, Kazuho; Mori, Takahisa; Archer, John A.C.

    2014-01-01

    The marine microbiome is a fundamental component of the biosphere. Its bacteria are abundant and play critical roles within the ocean environment. The majority of this important group of bacteria are genetically uncharacterized. Relatively few species have been studied in the laboratory. However, by applying metagenomic analyses to marine microbial populations, genomic ‘snapshots’ may be taken and from appropriate time series experiments their dynamics established. As a key component of the CBRC Centre Research Program (2014-2020), we are initiating a comparative study of the Red Sea and North Eastern Japanese coast and bay complexes. These environments differ in physical characteristics significantly. The Red Sea exhibits consistently high salinity, temperature and insolation characteristics, whereas the Japanese waters are less saline, cooler and receive lower insolation. Here, we present initial data and analytical pipelines for Phase 1 of our collaborative research program.

  14. Plankton motility patterns and encounter rates

    DEFF Research Database (Denmark)

    Visser, Andre; Kiørboe, Thomas

    2006-01-01

    measure of run length to reaction distance determines whether the underlying encounter is ballistic or diffusive. Since ballistic interactions are intrinsically more efficient than diffusive, we predict that organisms will display motility with long correlation run lengths compared to their reaction...... distances to their prey, but short compared to the reaction distances of their predators. We show motility data for planktonic organisms ranging from bacteria to copepods that support this prediction. We also present simple ballistic and diffusive motility models for estimating encounter rates, which lead...

  15. Simulated Sampling of Estuary Plankton

    Science.gov (United States)

    Fortner, Rosanne W.; Jenkins, Deborah Bainer

    2009-01-01

    To find out about the microscopic life in the valuable estuary environment, it is usually necessary to be near the water. This dry lab offers an alternative, using authentic data and a simulation of plankton sampling. From the types of organisms found in the sample, middle school students can infer relationships in the biological and physical…

  16. Comparative study of receiver-side ghost wavefield attenuation on different marine acquisition configurations

    Science.gov (United States)

    Zhang, Hao; Liu, Qiancheng; Li, Hongyuan; Zhang, Yi

    2018-04-01

    In marine seismic exploration, the ghost energies (down-going waves), which arise from the reflection at the surface, are often treated as unwanted signals for data processing. The ghost wave fields interfere with the desired primary signals, leads to frequency notches and attenuation of low frequencies, which in turn downgrade the resolution of the recorded seismic data. There are two main categories of methods to solve the ghost or the so-called notch problem: the non-conventional acquisition configuration-based technique and a deghosting algorithm-based solution. The variable-depth streamer (VDS) acquisition solution is one of the most representative methods in the first category, which has become a popular solution for marine seismic acquisition to obtain broad data bandwidth. However, this approach is not as economic as the conventional constant depth streamer (CDS) acquisition, due to the precise control of the towing streamer. In addition, there are large quantities of conventionally-towed legacy data stored in the data library. Applying receiver deghosting to the CDS data thus becomes a more economical method. In theory, both types of data after deghosting should have the same bandwidth and S/N ratio, but in reality they are different. In this paper, we conduct a comparative study and evaluation to apply receiver deghosting to a set of real 2D marine data including both types of acquisition (CDS and VDS) corresponding to the same geology. The deghosting algorithm we employed is a self-sustained, inversion-based approach operated in the τ-p domain. This evaluation can help us to understand two questions: whether the VDS acquisition has more broadband characteristics compared to conventional CDS acquisition after deghosting, and whether we can achieve the identical or similar data quality (e.g., S/N ratio) through the proper deghosting algorithm for both types of data. The comparative results are illustrated and discussed.

  17. Planktonic Euryarchaeota are a significant source of archaeal tetraether lipids in the ocean.

    Science.gov (United States)

    Lincoln, Sara A; Wai, Brenner; Eppley, John M; Church, Matthew J; Summons, Roger E; DeLong, Edward F

    2014-07-08

    Archaea are ubiquitous in marine plankton, and fossil forms of archaeal tetraether membrane lipids in sedimentary rocks document their participation in marine biogeochemical cycles for >100 million years. Ribosomal RNA surveys have identified four major clades of planktonic archaea but, to date, tetraether lipids have been characterized in only one, the Marine Group I Thaumarchaeota. The membrane lipid composition of the other planktonic archaeal groups--all uncultured Euryarchaeota--is currently unknown. Using integrated nucleic acid and lipid analyses, we found that Marine Group II Euryarchaeota (MG-II) contributed significantly to the tetraether lipid pool in the North Pacific Subtropical Gyre at shallow to intermediate depths. Our data strongly suggested that MG-II also synthesize crenarchaeol, a tetraether lipid previously considered to be a unique biomarker for Thaumarchaeota. Metagenomic datasets spanning 5 y indicated that depth stratification of planktonic archaeal groups was a stable feature in the North Pacific Subtropical Gyre. The consistent prevalence of MG-II at depths where the bulk of exported organic matter originates, together with their ubiquitous distribution over diverse oceanic provinces, suggests that this clade is a significant source of tetraether lipids to marine sediments. Our results are relevant to archaeal lipid biomarker applications in the modern oceans and the interpretation of these compounds in the geologic record.

  18. Comparability of data for natural radionuclides in marine sediment obtained by different analytical techniques

    International Nuclear Information System (INIS)

    Bojanowski, R.; Fukai, R.; Holm, E.

    1987-01-01

    The results of postassium, uranium, thorium and radium measurements performed on the natural marine sediment sample SD-N-1/2 in the framework of the IAEA-organized worldwide intercomparison excercise are presented. Analytical methods applied in this excercise were evaluated for performance, and significance of the observed discrepancies are discussed in the light of statistical and operative criteria. Possible sources of error were identified in alpha and gamma spectrometric measurements and suggestions are given about how to avoid them. Well characterized reference materials based on natural matrices are shown to be helpful in achieving better data comparability in low level measurements of environmental radioactivity. (author)

  19. Comparative proteomic analysis of extracellular proteins expressed by various clonal types of Staphylococcus aureus and during planktonic growth and biofilm development.

    Science.gov (United States)

    Atshan, Salman S; Shamsudin, Mariana N; Sekawi, Zamberi; Thian Lung, Leslie T; Barantalab, Fatemeh; Liew, Yun K; Alreshidi, Mateg Ali; Abduljaleel, Salwa A; Hamat, Rukman A

    2015-01-01

    Staphylococcus aureus is well known for its biofilm formation with rapid emergence of new clones circulating worldwide. The main objectives of the study were (1) to identify possible differences in protein expression among various and closely related clonal types of S. aureus, (2) to establish the differences in protein expression in terms of size of protein spots and its intensities between bacteria which are grown statically (biofilm formation) with that of under aeration and agitation, and (3) to compare the differences in protein expression as a function of time (in hours). In this study, we selected six clinical isolates comprising two similar (MRSA-527 and MRSA-524) and four different (MRSA-139, MSSA-12E, MSSA-22d, and MSSA-10E) types identified by spa typing, MLST and SCCmec typing. We performed 2D gel migration comparison. Also, two MRSA isolates (527 and 139) were selected to determine quantitative changes in the level of extracellular proteins at different biofilm growth time points of 12, 24, and 48 h. The study was done using a strategy that combines 2-DGE and LC-MS/MS analysis for absolute quantification and identification of the extracellular proteins. The 2DGE revealed that the proteomic profiles for the isolates belonging to the similar spa, MLST, and SCCmec types were still quite different. Among the extracellular proteins secreted at different time points of biofilm formation, significant changes in protein expression were observed at 48 h incubation as compared to the exponential growth at 12 h incubation. The main conclusion of the work is that the authors do observe differences among isolates, and growth conditions do influence the protein content at different time points of biofilm formation.

  20. Comparative analysis of food webs based on flow networks: effects of nutrient supply on structure and function of coastal plankton communities

    Science.gov (United States)

    Olsen, Yngvar; Reinertsen, Helge; Vadstein, Olav; Andersen, Tom; Gismervik, Ingrid; Duarte, Carlos; Agusti, Susana; Stibor, Herwig; Sommer, Ulrich; Lignell, Risto; Tamminen, Timo; Lancelot, Christiane; Rousseau, Veronique; Hoell, Espen; Sanderud, Knut Arvid

    2001-12-01

    The objective of COMWEB was to develop efficient analytical, numerical and experimental methods for assessing and predicting the effects of nutrient (N, P, Si) supply on the stability and persistence of pelagic food web structure and function in coastal waters. The experimental comparative work included a geographic gradient covering Baltic, Mediterranean, and NE Atlantic waters and a NE Atlantic gradient in state of eutrophication. COMWEB has been an experimental approach to coastal eutrophication, studying effects of enhanced nutrient supply on components and flows of the entire lower pelagic food web. Flow network representations of pelagic food webs has been a framework of data reduction and flows were established by sophisticated inverse modelling. Fundamental information on physiological properties of functional key species in the pelagic food web was used to constrain flow estimations. A main conclusion derived from the flow networks was that very little energy and materials were transferred from the microbial food web to the main food chain. The lower food web could therefore be described as two parallel food chains with relatively limited interaction between heterotrophic groups. Short-term effects of nutrient perturbations were examined in mesocosms along the geographic gradient. The response was comparable in all systems, with a stronger effect on the activity and biomass of autotrophic groups than those of heterotrophic ones. Mediterranean waters showed much lower autotrophic biomass response than Baltic and NE Atlantic waters, which responded almost equally. The response of primary production was, however, more comparable. High phytoplankton lysis rate explained this low accumulation of biomass in Mediterranean waters. The study of Atlantic coastal waters of different eutrophic states revealed that the ecological response was higher in the closed nutrient perturbed mesocosms than in open systems exposed for >4 summer months (summer/autumn season). The

  1. Moderate effect of damming the Romaine River (Quebec, Canada) on coastal plankton dynamics

    Science.gov (United States)

    Senneville, Simon; Schloss, Irene R.; St-Onge Drouin, Simon; Bélanger, Simon; Winkler, Gesche; Dumont, Dany; Johnston, Patricia; St-Onge, Isabelle

    2018-04-01

    Rivers' damming disrupts the seasonal cycle of freshwater and nutrient inputs into the marine system, which can lead to changes in coastal plankton dynamics. Here we use a 3-D 5-km resolution coupled biophysical model and downscale it to a 400-m resolution to simulate the effect of damming the Romaine River in Québec, Canada, which discharges on average 327 m3 s-1 of freshwater into the northern Gulf of St. Lawrence. Model results are compared with environmental data obtained from 2 buoys and in situ sampling near the Romaine River mouth during the 2013 spring-summer period. Noteworthy improvements are made to the light attenuation parametrization and the trophic links of the biogeochemical model. The modelled variables reproduced most of the observed levels of variability. Comparisons between natural and regulated discharge simulation show differences in primary production and in the dominance of plankton groups in the Romaine River plume. The maximum increase in primary production when averaged over the inner part of Mingan Archipelago is 41%, but 7.1% when the primary production anomaly is averaged from March to September.

  2. Comparative toxicity test of water-accommodated fractions of oils and oil dispersants to marine organisms

    International Nuclear Information System (INIS)

    1989-01-01

    This reference method describes a simple procedure for comparing the toxicity of oil, oil dispersants, and mixtures thereof, to marine animals. It allows the toxicity of different dispersants to be rapidly compared to that of oil, or of a mixture of oil an oil dispersant. It is designed for routine monitoring and screening purposes and is not appropriate as a research method. The physical and chemical properties of oil dispersants create many difficulties in the measurements of their toxicity to marine organisms. Strictly speaking, their toxicity can only be accurately estimated using complex procedures and apparatus. (A relatively simple apparatus for preparing oil/water or oil/water/oil dispersant emulsions is described in Appendix B). Simpler methods can provide useful information, provided their limitations are clearly understood and taken into consideration in the assessment and application of their results. Some of the special considerations relating to the measurement of the toxicity of oil and oil dispersants are described in Appendix A. The Appendix also explains the rationale and limitations of the method described here. 3 refs, 4 figs, 2 tabs

  3. Assessment of marine gas hydrate deposits: A comparative study of seismic, electromagnetic and seafloor compliance methods

    Energy Technology Data Exchange (ETDEWEB)

    Willoughby, E. C.; Schwalenberg, K.; Edwards, R.N.; Spence, G.D.; Hyndman, R.D.

    2005-07-01

    The existence, distribution and concentration of marine natural gas hydrate are mostly diagnosed using seismic data. The base of the hydrate stability zone marks an acoustic impedance contrast, which generally mimics seafloor topography and is associated with a bright, negative-polarity reflector, known as the Bottom Simulating Reflector (BSR). However, limitations of seismic methods include uncertainty in the origin of the BSR, which does not distinguish between low velocity gas and high velocity hydrate, blanking, and lack of clear upper boundary reflections. Sufficiently accurate hydrate layer velocities have been obtained at few sites, and these could better evaluate hydrate content with reference to velocities in similar sediments without hydrate- a situation very difficult to find. Therefore, estimation of the total mass of a deposit is difficult using seismic data alone. We have developed two supplementary geophysical imaging techniques for the evaluation of marine hydrate: A deep-towed controlled-source electromagnetic (CSEM) and a seafloor compliance experiment. These methods are sensitive to physical properties of the sedimentary section, which are modified by the presence of gas hydrate, namely the resistivity and the bulk shear modulus depth profile, respectively. CSEM data are gathered by inline receivers towed behind an AC transmitter; high precision timing allows measurement of the EM field propagation time through marine sediments which is proportional to resistivity, which is increased by the presence of insulating hydrate. Seafloor compliance is the transfer function between pressure induced on the seafloor by surface gravity waves and the associated deformation of the seafloor. It is mostly sensitive to shear modulus anomalies. Shear modulus is increased by hydrates, which can cement grains together. Here we present field data at a gas hydrate site, south of ODP Hole 889B in northern Cascadia, over a proposed new IODP transect, where these three

  4. Automatic plankton image classification combining multiple view features via multiple kernel learning.

    Science.gov (United States)

    Zheng, Haiyong; Wang, Ruchen; Yu, Zhibin; Wang, Nan; Gu, Zhaorui; Zheng, Bing

    2017-12-28

    Plankton, including phytoplankton and zooplankton, are the main source of food for organisms in the ocean and form the base of marine food chain. As the fundamental components of marine ecosystems, plankton is very sensitive to environment changes, and the study of plankton abundance and distribution is crucial, in order to understand environment changes and protect marine ecosystems. This study was carried out to develop an extensive applicable plankton classification system with high accuracy for the increasing number of various imaging devices. Literature shows that most plankton image classification systems were limited to only one specific imaging device and a relatively narrow taxonomic scope. The real practical system for automatic plankton classification is even non-existent and this study is partly to fill this gap. Inspired by the analysis of literature and development of technology, we focused on the requirements of practical application and proposed an automatic system for plankton image classification combining multiple view features via multiple kernel learning (MKL). For one thing, in order to describe the biomorphic characteristics of plankton more completely and comprehensively, we combined general features with robust features, especially by adding features like Inner-Distance Shape Context for morphological representation. For another, we divided all the features into different types from multiple views and feed them to multiple classifiers instead of only one by combining different kernel matrices computed from different types of features optimally via multiple kernel learning. Moreover, we also applied feature selection method to choose the optimal feature subsets from redundant features for satisfying different datasets from different imaging devices. We implemented our proposed classification system on three different datasets across more than 20 categories from phytoplankton to zooplankton. The experimental results validated that our system

  5. Comparative analysis of marine paleogene sections and biota from West Siberia and the Arctic Region

    Science.gov (United States)

    Akhmet'ev, M. A.; Zaporozhets, N. I.; Iakovleva, A. I.; Aleksandrova, G. N.; Beniamovsky, V. N.; Oreshkina, T. V.; Gnibidenko, Z. N.; Dolya, Zh. A.

    2010-12-01

    The analysis of the main biospheric events that took place in West Siberia and the Arctic region during the Early Paleogene revealed the paleogeographic and paleobiogeographic unity of marine sedimentation basins and close biogeographic relations between their separate parts. Most biotic and abiotic events of the first half of the Paleogene in the Arctic region and West Siberia were synchronous, unidirectional, and interrelated. Shelf settings, sedimentation breaks, and microfaunal assemblages characteristic of these basins during the Paleogene are compared. The comparative analysis primarily concerned events of the Paleocene-Eocene thermal maximum (PETM) and beds with Azolla (aquatic fern). The formation of the Eocene Azolla Beds in the Arctic region and West Siberia was asynchronous, although it proceeded in line with a common scenario related to the development of a system of estuarine-type currents in a sea basin partly isolated from the World Ocean.

  6. Trophic strategies of unicellular plankton

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Nielsen, Lasse Tor; Andersen, Ken Haste

    2017-01-01

    . To this end, we develop and calibrate a trait-based model for unicellular planktonic organisms characterized by four traits: cell size and investments in phototrophy, nutrient uptake, and phagotrophy. We use the model to predict how optimal trophic strategies depend on cell size under various environmental...... unicellulars are colimited by organic carbon and nutrients, and only large photoautotrophs and smaller mixotrophs are nutrient limited; (2) trophic strategy is bottom-up selected by the environment, while optimal size is top-down selected by predation. The focus on cell size and trophic strategies facilitates......Unicellular plankton employ trophic strategies ranging from pure photoautotrophs over mixotrophy to obligate heterotrophs (phagotrophs), with cell sizes from 10-8 to 1 μg C. A full understanding of how trophic strategy and cell size depend on resource environment and predation is lacking...

  7. Drivers of Plankton Patch Formation, Persistence and Decline in East Sound, Orcas Island, Washington

    Science.gov (United States)

    2012-09-30

    Population dynamics of the marine planktonic ciliate Strombidinopsis multiauris: its potential to control phytoplankton blooms . Aquat. Microb. Ecol., 20...radii with patch exploitation in the coastal ocean. 5th International Zooplankton Production Symposium. Pucón, Chile Menden-Deuer S & Harvey* EL

  8. Plankton Dynamics and Mesoscale Turbulence

    Science.gov (United States)

    2010-06-29

    transformation of inorganic materials and light into living matter by photosynthesis) is operated mainly by small, unicellular algae that float freely in the...Aquatic ecosystems are characterized by the essential role played by fluid dynamics. The small organisms which compose the plankton are advected by the...surrounding flow and must cope with environmental currents, turbulence, and waves. And those organisms which anchor themselves to the rocks and to the

  9. Coastal and marine biodiversity of India

    Digital Repository Service at National Institute of Oceanography (India)

    Venkataraman, K.; Wafar, M.V.M.

    endangered eco-regions of the world 1 . Among the Asian countries, India is perhaps the only one that has a long INDIAN J. MAR. SCI., VOL. 34, No. 1, MARCH 2005 58 record of inventories of coastal and marine biodiversity dating back to at least two..., planktonic algae appear to have been more completely catalogued 2,3 . Their compilation suggests that the number of pennate diatoms in the world oceans could range from 500 to 784 and that of centric diatoms, from 865 to 999. Compared with these, not more...

  10. Comparative taphonomy, taphofacies, and bonebeds of the Mio-Pliocene Purisima Formation, central California: strong physical control on marine vertebrate preservation in shallow marine settings.

    Directory of Open Access Journals (Sweden)

    Robert W Boessenecker

    Full Text Available Taphonomic study of marine vertebrate remains has traditionally focused on single skeletons, lagerstätten, or bonebed genesis with few attempts to document environmental gradients in preservation. As such, establishment of a concrete taphonomic model for shallow marine vertebrate assemblages is lacking. The Neogene Purisima Formation of Northern California, a richly fossiliferous unit recording nearshore to offshore depositional settings, offers a unique opportunity to examine preservational trends across these settings.Lithofacies analysis was conducted to place vertebrate fossils within a hydrodynamic and depositional environmental context. Taphonomic data including abrasion, fragmentation, phosphatization, articulation, polish, and biogenic bone modification were recorded for over 1000 vertebrate fossils of sharks, bony fish, birds, pinnipeds, odontocetes, mysticetes, sirenians, and land mammals. These data were used to compare both preservation of multiple taxa within a single lithofacies and preservation of individual taxa across lithofacies to document environmental gradients in preservation. Differential preservation between taxa indicates strong preservational bias within the Purisima Formation. Varying levels of abrasion, fragmentation, phosphatization, and articulation are strongly correlative with physical processes of sediment transport and sedimentation rate. Preservational characteristics were used to delineate four taphofacies corresponding to inner, middle, and outer shelf settings, and bonebeds. Application of sequence stratigraphic methods shows that bonebeds mark major stratigraphic discontinuities, while packages of rock between discontinuities consistently exhibit onshore-offshore changes in taphofacies.Changes in vertebrate preservation and bonebed character between lithofacies closely correspond to onshore-offshore changes in depositional setting, indicating that the dominant control of preservation is exerted by physical

  11. Comparative taphonomy, taphofacies, and bonebeds of the Mio-Pliocene Purisima Formation, central California: strong physical control on marine vertebrate preservation in shallow marine settings.

    Science.gov (United States)

    Boessenecker, Robert W; Perry, Frank A; Schmitt, James G

    2014-01-01

    Taphonomic study of marine vertebrate remains has traditionally focused on single skeletons, lagerstätten, or bonebed genesis with few attempts to document environmental gradients in preservation. As such, establishment of a concrete taphonomic model for shallow marine vertebrate assemblages is lacking. The Neogene Purisima Formation of Northern California, a richly fossiliferous unit recording nearshore to offshore depositional settings, offers a unique opportunity to examine preservational trends across these settings. Lithofacies analysis was conducted to place vertebrate fossils within a hydrodynamic and depositional environmental context. Taphonomic data including abrasion, fragmentation, phosphatization, articulation, polish, and biogenic bone modification were recorded for over 1000 vertebrate fossils of sharks, bony fish, birds, pinnipeds, odontocetes, mysticetes, sirenians, and land mammals. These data were used to compare both preservation of multiple taxa within a single lithofacies and preservation of individual taxa across lithofacies to document environmental gradients in preservation. Differential preservation between taxa indicates strong preservational bias within the Purisima Formation. Varying levels of abrasion, fragmentation, phosphatization, and articulation are strongly correlative with physical processes of sediment transport and sedimentation rate. Preservational characteristics were used to delineate four taphofacies corresponding to inner, middle, and outer shelf settings, and bonebeds. Application of sequence stratigraphic methods shows that bonebeds mark major stratigraphic discontinuities, while packages of rock between discontinuities consistently exhibit onshore-offshore changes in taphofacies. Changes in vertebrate preservation and bonebed character between lithofacies closely correspond to onshore-offshore changes in depositional setting, indicating that the dominant control of preservation is exerted by physical processes. The

  12. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    International Nuclear Information System (INIS)

    Hamilton, T.F.; Smith, J.D.

    1991-01-01

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and 241 Am was low, with specific activity in the tissues 241 Am occurred and 241 Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author)

  13. The influence of historical climate changes on Southern Ocean marine predator populations: a comparative analysis.

    Science.gov (United States)

    Younger, Jane L; Emmerson, Louise M; Miller, Karen J

    2016-02-01

    The Southern Ocean ecosystem is undergoing rapid physical and biological changes that are likely to have profound implications for higher-order predators. Here, we compare the long-term, historical responses of Southern Ocean predators to climate change. We examine palaeoecological evidence for changes in the abundance and distribution of seabirds and marine mammals, and place these into context with palaeoclimate records in order to identify key environmental drivers associated with population changes. Our synthesis revealed two key factors underlying Southern Ocean predator population changes; (i) the availability of ice-free ground for breeding and (ii) access to productive foraging grounds. The processes of glaciation and sea ice fluctuation were key; the distributions and abundances of elephant seals, snow petrels, gentoo, chinstrap and Adélie penguins all responded strongly to the emergence of new breeding habitat coincident with deglaciation and reductions in sea ice. Access to productive foraging grounds was another limiting factor, with snow petrels, king and emperor penguins all affected by reduced prey availability in the past. Several species were isolated in glacial refugia and there is evidence that refuge populations were supported by polynyas. While the underlying drivers of population change were similar across most Southern Ocean predators, the individual responses of species to environmental change varied because of species specific factors such as dispersal ability and environmental sensitivity. Such interspecific differences are likely to affect the future climate change responses of Southern Ocean marine predators and should be considered in conservation plans. Comparative palaeoecological studies are a valuable source of long-term data on species' responses to environmental change that can provide important insights into future climate change responses. This synthesis highlights the importance of protecting productive foraging grounds

  14. PFR²: a curated database of planktonic foraminifera 18S ribosomal DNA as a resource for studies of plankton ecology, biogeography and evolution.

    Science.gov (United States)

    Morard, Raphaël; Darling, Kate F; Mahé, Frédéric; Audic, Stéphane; Ujiié, Yurika; Weiner, Agnes K M; André, Aurore; Seears, Heidi A; Wade, Christopher M; Quillévéré, Frédéric; Douady, Christophe J; Escarguel, Gilles; de Garidel-Thoron, Thibault; Siccha, Michael; Kucera, Michal; de Vargas, Colomban

    2015-11-01

    Planktonic foraminifera (Rhizaria) are ubiquitous marine pelagic protists producing calcareous shells with conspicuous morphology. They play an important role in the marine carbon cycle, and their exceptional fossil record serves as the basis for biochronostratigraphy and past climate reconstructions. A major worldwide sampling effort over the last two decades has resulted in the establishment of multiple large collections of cryopreserved individual planktonic foraminifera samples. Thousands of 18S rDNA partial sequences have been generated, representing all major known morphological taxa across their worldwide oceanic range. This comprehensive data coverage provides an opportunity to assess patterns of molecular ecology and evolution in a holistic way for an entire group of planktonic protists. We combined all available published and unpublished genetic data to build PFR(2), the Planktonic foraminifera Ribosomal Reference database. The first version of the database includes 3322 reference 18S rDNA sequences belonging to 32 of the 47 known morphospecies of extant planktonic foraminifera, collected from 460 oceanic stations. All sequences have been rigorously taxonomically curated using a six-rank annotation system fully resolved to the morphological species level and linked to a series of metadata. The PFR(2) website, available at http://pfr2.sb-roscoff.fr, allows downloading the entire database or specific sections, as well as the identification of new planktonic foraminiferal sequences. Its novel, fully documented curation process integrates advances in morphological and molecular taxonomy. It allows for an increase in its taxonomic resolution and assures that integrity is maintained by including a complete contingency tracking of annotations and assuring that the annotations remain internally consistent. © 2015 John Wiley & Sons Ltd.

  15. Foraging strategy switch of a top marine predator according to seasonal resource differences

    Directory of Open Access Journals (Sweden)

    Malcolm Daniel O'Toole

    2015-04-01

    Full Text Available The spatio-temporal variability in marine resources influences the foraging behaviour and success of top marine predators. However, little is known about the links between these animals and ocean productivity, specifically, how plankton density influences their foraging behaviour. Southern elephant seals (Mirounga leonina have two annual at-sea foraging trips: a two month post-breeding foraging trip (Nov – Jan that coincides with elevated summer productivity; and an eight month post-moulting foraging trip (Feb – Oct over winter, when productivity is low. Physical parameters are often used to describe seal habitat, whereas information about important biological parameters is lacking. We used electronic tags deployed on elephant seals during both trips to determine their movement and foraging behaviour. The tags also recorded light, which measured the bio-optical properties of the water column, the bulk of which is presumably influenced by phytoplankton. We investigated the relationship between plankton density and seal foraging behaviour; comparing trends between summer and winter trips. We found a positive relationship between plankton density and foraging behaviour, which did not vary seasonally. We propose that profitable concentrations of seal prey are more likely to coincide with planktonic aggregations, but we also acknowledge that trophic dynamics may shift in response to seasonal trends in productivity. Seal prey (mid-trophic level and plankton (lower-trophic level are expected to overlap in space and time during summer trips when peak phytoplankton blooms occur. In contrast, aggregated patches of lower trophic levels are likely to be more dispersed during winter trips when plankton density is considerably lower and heterogeneous. These results show that southern elephant seals are able to exploit prey resources in different ways throughout the year as demonstrated by the variation observed between seal foraging behaviour and trophic

  16. Progress Towards a Global Understanding of Plankton Dynamics: The Global Alliance of CPR Surveys (GACS)

    Science.gov (United States)

    Batten, S.; Richardson, A.; Melrose, C.; Muxagata, E.; Hosie, G.; Verheye, H.; Hall, J.; Edwards, M.; Koubbi, P.; Abu-Alhaija, R.; Chiba, S.; Wilson, W.; Nagappa, R.; Takahashi, K.

    2016-02-01

    The Continuous Plankton Recorder (CPR) was first used in 1931 to routinely sample plankton and its continued deployment now sustains the longest-running, and spatially most extensive marine biological sampling programme in the world. Towed behind, for the most part commercial, ships it collects plankton samples from the surface waters that are subsequently analysed to provide taxonomically-resolved abundance data on a broad range of planktonic organisms from the size of coccolithophores to euphausiids. Plankton appear to integrate changes in the physical environment and by underpinning most marine food-webs, pass on this variability to higher trophic levels which have societal value. CPRs are deployed increasingly around the globe in discrete regional surveys that until recently interacted in an informal way. In 2011 the Global Alliance of CPR Surveys (GACS) was launched to bring these surveys together to collaborate more productively and address issues such as: methodological standardization, data integration, capacity building, and data analysis. Early products include a combined global database and regularly-released global marine ecological status reports. There are, of course, limitations to the exploitation of CPR data as well as the current geographic coverage. A current focus of GACS is integration of the data with models to meaningfully extrapolate across time and space. In this way the output could be used to provide more robust synoptic representations of key plankton variables. Recent years have also seen the CPR used as a platform in itself with the inclusion of additional sensors and water samplers that can sample the microplankton. The archive of samples has already been used for some molecular investigations and curation of samples is maintained for future studies. Thus the CPR is a key element of any regional to global ocean observing system of biodiversity.

  17. Comparative Genomics Highlights Symbiotic Capacities and High Metabolic Flexibility of the Marine Genus Pseudovibrio.

    Science.gov (United States)

    Versluis, Dennis; Nijsse, Bart; Naim, Mohd Azrul; Koehorst, Jasper J; Wiese, Jutta; Imhoff, Johannes F; Schaap, Peter J; van Passel, Mark W J; Smidt, Hauke; Sipkema, Detmer

    2018-01-01

    Pseudovibrio is a marine bacterial genus members of which are predominantly isolated from sessile marine animals, and particularly sponges. It has been hypothesized that Pseudovibrio spp. form mutualistic relationships with their hosts. Here, we studied Pseudovibrio phylogeny and genetic adaptations that may play a role in host colonization by comparative genomics of 31 Pseudovibrio strains, including 25 sponge isolates. All genomes were highly similar in terms of encoded core metabolic pathways, albeit with substantial differences in overall gene content. Based on gene composition, Pseudovibrio spp. clustered by geographic region, indicating geographic speciation. Furthermore, the fact that isolates from the Mediterranean Sea clustered by sponge species suggested host-specific adaptation or colonization. Genome analyses suggest that Pseudovibrio hongkongensis UST20140214-015BT is only distantly related to other Pseudovibrio spp., thereby challenging its status as typical Pseudovibrio member. All Pseudovibrio genomes were found to encode numerous proteins with SEL1 and tetratricopeptide repeats, which have been suggested to play a role in host colonization. For evasion of the host immune system, Pseudovibrio spp. may depend on type III, IV, and VI secretion systems that can inject effector molecules into eukaryotic cells. Furthermore, Pseudovibrio genomes carry on average seven secondary metabolite biosynthesis clusters, reinforcing the role of Pseudovibrio spp. as potential producers of novel bioactive compounds. Tropodithietic acid, bacteriocin, and terpene biosynthesis clusters were highly conserved within the genus, suggesting an essential role in survival, for example through growth inhibition of bacterial competitors. Taken together, these results support the hypothesis that Pseudovibrio spp. have mutualistic relations with sponges. © The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  18. Plankton composition and biomass development

    DEFF Research Database (Denmark)

    Jakobsen, H.H.; Jepsen, P.M.; Blanda, E.

    2016-01-01

    Plankton food web dynamics were studied during a complete production season in a semi-intensive land-based facility for rearing of turbot (Scophthalmus maximus) larvae. The production season was divided into three production cycles of 3–5 weeks. Phytoplankton biomass (using chlorophyll a as biomass...... proxy) peaked in each production cycle. However, the maximum biomass decreased from spring (18 μg chlorophyll a L−1) to fall (ca. 7 μg chlorophyll a L−1), simultaneous with a decline in the concentration of dissolved nitrogen in the inoculating water. During the three production cycles, we observed...

  19. Hydromechanical signals in the plankton

    DEFF Research Database (Denmark)

    Visser, Andre

    2001-01-01

    The distance at which plankters can detect and thus interact with each other depends on their sensitivity, size, and motion, as well as the hydrodynamic characteristics of their behaviour. Through a simple consideration of the distribution of forces exerted on the ambient fluid by different...... proportional to a(3)Ur(-3). Within this context, observed planktonic interactions, particularly for copepods, were analysed and showed reasonably good support for the theory. The remote detection of inert particles by feeding-current-generating and free-swimming copepods was found to be feasible for known...... swimming ciliates under turbulent conditions showed good agreement with previously reported observations....

  20. Studies on marine ecosystem in particular emphasis on phytoplankton (lecture by the member awarded the oceanographic society of Japan prize for 1992). Shokubutsu plankton wo chushintoshita kaiyo seitaikei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, M. (The University of Tokyo, Tokyo (Japan). Faculty of Science)

    1993-06-25

    This paper, while introducing major study results of the author, summarizes his studies on ecosystems in lakes and oceans with respect mainly to phytoplanktons. The studies include the following subjects: A proposal on mathematical model equations to estimate growth of photosynthetic bacterial populations in deep lake beds; evaluation of stimulative effects for photosynthetic production provided by fertilizer application in lakes, and influences of phytoplanktons on population structures; evaluation on effects imposed on ecosystems from dumping chemical substances, as observed in experimental ecosystems that incorporate part of marine ecosystems; correlation between red-tide life absorbing proliferation stimulating substances and red tide generation; growth of high-concentration phytoplankton populations containing algae as a dominant species in local upwelling environments in oceans; and verification on establishment of specific phytoplankton populations containing pico-phytoplankton as a dominant species in oligotrophic environments in open seas. The paper mentions influences of the author's book, Biological Oceanographic Processes under joint authorship with Parsons on marine ecosystem researchers. 66 refs., 8 figs.

  1. De scheiding van slib en plankton

    NARCIS (Netherlands)

    Budding, M.C.

    1974-01-01

    It is possible to separate non-living suspended matter and living plankton with the help of a common laboratory centrifuge and a commercial silica-gel called LUDOX. With this method it becomes possible to determine particle size of suspended matter and plankton separately with e.g. a Coulter

  2. Comparing the sensitivity of permafrost and marine gas hydrate to climate warming

    International Nuclear Information System (INIS)

    Taylor, A.E.; Dallimore, S.R.; Hyndman, R.D.; Wright, F.

    2005-01-01

    The sensitivity of Arctic subpermafrost gas hydrate at the Mallik borehole was compared to temperate marine gas hydrate located offshore southwestern Canada. In particular, a finite element geothermal model was used to determine the sensitivity to the end of the ice age, and contemporary climate warming of a 30 m thick methane hydrate layer lying at the base of a gas hydrate stability zone prior to 13.5 kiloannum (ka) before present (BP). It was suggested that the 30 m gas-hydrate-bearing layer would have disappeared by now, according to the thermal signal alone. However, the same gas-hydrate-bearing layer underlying permafrost would persist until at least 4 ka after present, even with contemporary climate warming. The longer time for subpermafrost gas hydrate comes from the thawing pore ice at the base of permafrost, at the expense of dissociation of the deeper gas hydrate. The dissociation of underlying gas hydrate from climate surface warming is buffered by the overlying permafrost

  3. A Comparative Study of Vocabulary Learning Strategies Used by Marine Engineering Students and Iranian EFL Learners

    Directory of Open Access Journals (Sweden)

    Davood Mashhadi Heidar

    2017-11-01

    Full Text Available The present study explored the vocabulary learning strategies used by Iranian EFL learners and Marine Engineering (ME students by using the categorization of vocabulary learning strategies proposed by Schmitt (1997. A vocabulary learning strategies questionnaire was administered to 30 EFL learners and 43 ME students. Then, the strategies used by each group were determined and the two groups were compared with each other. It was found that both groups used determination strategies more frequently than social strategies for discovering a new word’s meaning. The most frequently used discovery strategy by both groups was found to be “bilingual dictionary”. The second and third most frequently used strategy for discovery by EFL learners and ME students was found to be “monolingual dictionary” and “guess from textual context”, respectively. It was also revealed that EFL learners used memory strategies more frequently than other strategies for consolidating the meaning of new words and ME students used cognitive strategies the most frequently. Both groups were found to use “verbal repetition” more frequently than all other consolidation strategies. The second most frequently used strategy by EFL learners was “use Englishlanguage media” whilst for ME students they were “written repetition” and “word lists”. The comparison of the strategy use by the participants in the two groups showed no significant difference.

  4. Comparative study of plutonium and americium bioaccumulation from two marine sediments contaminated in the natural environment

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, T.F.; Smith, J.D. (Melbourne Univ., Parkville (Australia). Dept. of Inorganic Chemistry); Fowler, S.W.; LaRosa, J.; Holm, E. (International Atomic Energy Agency, Monaco-Ville (Monaco). Lab. of Marine Radioactivity); Aarkrog, A.; Dahlgaard, H. (Risoe National Lab., Roskilde (Denmark))

    1991-01-01

    Plutonium and americium sediment-animal transfer was studied under controlled laboratory conditions by exposure of the benthic polychaete Nereis diversicolor (O. F. Mueller) to marine sediments contaminated by a nuclear bomb accident (near Thule, Greenland) and nuclear weapons testing (Enewetak Atoll). In both sediment regimes, the bioavailability of plutonium and {sup 241}Am was low, with specific activity in the tissues <1% (dry wt) than in the sediments. Over the first three months, a slight preference in transfer of plutonium over {sup 241}Am occurred and {sup 241}Am uptake from the Thule sediment was enhanced compared to that from lagoon sediments of Enewetak Atoll. Autoradiography studies indicated the presence of hot particles of plutonium in the sediments. The results highlight the importance of purging animals of their gut contents in order to obtain accurate estimates of transuranic transfer from ingested sediments into tissue. It is further suggested that enhanced transuranic uptake by some benthic species could arise from ingestion of highly activity particles and organic-rich detritus present in the sediments. (author).

  5. The effects of the Sea Empress oil spill on the plankton of the Southern Irish Sea

    International Nuclear Information System (INIS)

    Batten, S.D.; Allen, R.J.S.; Wotton, C.O.M.

    1998-01-01

    This study investigates the effects of the Sea Empress oil spill on the local plankton communities which are an important component of the marine ecosystem. The Continuous Plankton Recorder survey has monitored the plankton in this area since 1970 giving an extensive time series for comparison with post-spill samples. The analytical procedures applied and results obtained are presented and reveal that, with some exceptions, no significant effects were evident. Barnacle larvae were not recorded post-spill and the spring zooplankton community was somewhat different to the previous year. A long-term trend is apparent in the community but the most common taxa showed no significant changes, suggesting a minor shift in species composition rather than a dramatic change. (author)

  6. Public attitudes towards marine aquaculture: A comparative analysis of Germany and Israel

    International Nuclear Information System (INIS)

    Freeman, Shirra; Vigoda-Gadot, Eran; Sterr, Horst; Schultz, Michael; Korchenkov, Irina; Krost, Peter; Angel, Dror

    2012-01-01

    We report on bi-national (Germany–Israel) research on relationships between public attitudes, behaviours and preferences related to marine aquaculture. Aquaculture's world-wide market share accounts for over half of all aquatic products. In many places, the sector's explosive growth has outstripped scientific knowledge and governance provisions. Small producers such as Israel and Germany seeking to expand domestic production must address environmental challenges posed by fish farming, stakeholder competition in crowded coastal zones and public/consumer receptiveness. Based on survey data obtained from both the countries, correlation analysis (Pearson's r-statistic) was used to test four hypotheses. Of these, one (positive relationship between coastal tourism and aquaculture attitudes) was supported in both countries. The hypothesis of positive relationships between lifestyle (environment/health) behaviours and aquaculture attitudes was supported only in Germany and the hypothesis of negative relationships between concern for the environment and aquaculture attitudes was supported only in Israel. These results are significant for policy, business, NGO and other stakeholders. Moreover, they point to the importance of this type of comparative research in improving our understanding of local factors influencing attitude-formation and inter-relationships. First, the tourism–aquaculture relationship found indicates potential synergies between two sectors reliant on the coastal zone that should be taken into account by planning authorities. The divergent environment–aquaculture results were especially interesting since in both countries, the primary concern regarding aquaculture expansion was environmental impacts. Closer inspection of the survey results revealed that this relationship may have been influenced by the orientation of environmental concerns in each population. Germans focus on depletion of wildstocks and Israelis on cage effluent and marine pollution

  7. Planktonic foraminifera in the Arctic: potentials and issues regarding modern and quaternary populations

    International Nuclear Information System (INIS)

    Eynaud, Frederique

    2011-01-01

    Calcareous microfossils are widely used by paleoceanographers to investigate past sea-surface hydrology. Among these microfossils, planktonic foraminifera are probably the most extensively used tool (e.g. [1] for a review), as they are easy to extract from the sediment and can also be used for coupled geochemical (e.g; δ 18 O, δ 13 C, Mg/Ca) and paleo-ecological investigations. Planktonic foraminifera are marine protists, which build a calcareous shell made of several chambers which reflect in their chemistry the properties of the ambient water-masses. Planktonic foraminifera are known to thrive in various habitats, distributed not only along a latitudinal gradient, but also along different water-depth intervals within surface waters (0-1000 m). Regarding their biogeographical distribution, planktonic foraminifera assemblages therefore mirror different water-masses properties, such as temperature, salinity and nutrient content of the surface water in which they live. The investigation of the specific composition of a fossil assemblage (relative abundances) is therefore a way to empirically obtain (paleo)information on past variations of sea-surface hydrological parameters. This paper focuses on the planktonic foraminifera record from the Arctic domain. This polar region records peculiar sea-surface conditions, with the influence of nearly perennial sea-ice cover development. This has strong impact on living foraminifera populations and on the preservation of their shells in the underlying sediments.

  8. Planktonic foraminifera in the Arctic: potentials and issues regarding modern and quaternary populations

    Energy Technology Data Exchange (ETDEWEB)

    Eynaud, Frederique, E-mail: f.eynaud@epoc.u-bordeaux1.fr [Universite Bordeaux I, Laboratoire EPOC (Environnements et Paleoenvironnements OCeaniques), UMR CNRS 5805, Avenue des facultes, 33405 Talence cedex - France (France)

    2011-05-15

    Calcareous microfossils are widely used by paleoceanographers to investigate past sea-surface hydrology. Among these microfossils, planktonic foraminifera are probably the most extensively used tool (e.g. [1] for a review), as they are easy to extract from the sediment and can also be used for coupled geochemical (e.g; {delta}{sup 18}O, {delta}{sup 13}C, Mg/Ca) and paleo-ecological investigations. Planktonic foraminifera are marine protists, which build a calcareous shell made of several chambers which reflect in their chemistry the properties of the ambient water-masses. Planktonic foraminifera are known to thrive in various habitats, distributed not only along a latitudinal gradient, but also along different water-depth intervals within surface waters (0-1000 m). Regarding their biogeographical distribution, planktonic foraminifera assemblages therefore mirror different water-masses properties, such as temperature, salinity and nutrient content of the surface water in which they live. The investigation of the specific composition of a fossil assemblage (relative abundances) is therefore a way to empirically obtain (paleo)information on past variations of sea-surface hydrological parameters. This paper focuses on the planktonic foraminifera record from the Arctic domain. This polar region records peculiar sea-surface conditions, with the influence of nearly perennial sea-ice cover development. This has strong impact on living foraminifera populations and on the preservation of their shells in the underlying sediments.

  9. Comparative copper sensitivity between life stages of common subantarctic marine invertebrates.

    Science.gov (United States)

    Holan, Jessica R; King, Catherine K; Davis, Andrew R

    2018-03-01

    The development of environmental guidelines in the Antarctic and subantarctic is essential, because expansion of research, tourism, and fishing is placing these regions at increasing risk of contamination. Data are currently insufficient to create the region-specific guidelines needed for the unique conditions in these areas. To develop the most appropriate environmental guidelines, data from the most sensitive life stages of a species should be included to ensure effective protection throughout its life cycle. It is generally accepted that early life stages are more sensitive to contaminants. We compared the toxicity of copper between juvenile and adult life stages of 4 subantarctic marine invertebrates using sublethal and lethal endpoints. For 2 of the species tested, juveniles were more sensitive than adults. (The 7-d median effect concentration [EC50] values for the gastropod Laevilittorina caliginosa were 79 μg/L at the juvenile stage and 125 μg/L at the adult; for the flatworm Obrimoposthia ohlini, values were 190 μg/L at the juvenile stage and 300 μg/L at the adult.) For the isopod Limnoria stephenseni, juveniles were either more sensitive or of equal sensitivity to adults (7-d EC50 values: juvenile 278 μg/L and adult 320 μg/L). In contrast, for the bivalve Gaimardia trapesina, adults appeared to be more sensitive than young adults (7-d EC50 values: juvenile 23 μg/L and adult life history stages was observed, the present study contributes important information for the development of water quality guidelines in polar regions. Environ Toxicol Chem 2018;37:807-815. © 2017 SETAC. © 2017 SETAC.

  10. Dosimetry of natural and man-made alpha emitters in plankton

    International Nuclear Information System (INIS)

    Paschoa, A.S.; Baptista, G.B.; Wrenn, M.E.; Eisenbrid, M.

    1980-11-01

    Comparison between the natural and man-made alpha radiation dose rates to plankton can be important for predicting the potential long-term effects on aquatic biota resulting from the routine or accidental radioactive releases from the nuclear fuel cycle. A contribution is made here towards the goal of comparing natural with man-made alpha radiation dose rates to plankton using the same method of calculation in both cases. (Author) [pt

  11. Persistent organic pollutants in Mediterranean seawater and processes affecting their accumulation in plankton.

    Science.gov (United States)

    Berrojalbiz, Naiara; Dachs, Jordi; Del Vento, Sabino; Ojeda, María José; Valle, María Carmen; Castro-Jiménez, Javier; Mariani, Giulio; Wollgast, Jan; Hanke, Georg

    2011-05-15

    The Mediterranean and Black Seas are unique marine environments subject to important anthropogenic pressures due to riverine and atmospheric inputs of organic pollutants. Here, we report the results obtained during two east-west sampling cruises in June 2006 and May 2007 from Barcelona to Istanbul and Alexandria, respectively, where water and plankton samples were collected simultaneously. Both matrixes were analyzed for hexaclorochyclohexanes (HCHs), hexachlorobenzene (HCB), and 41 polychlorinated biphenyl (PCB) congeners. The comparison of the measured HCB and HCHs concentrations with previously reported dissolved phase concentrations suggests a temporal decline in their concentrations since the 1990s. On the contrary, PCB seawater concentrations did not exhibit such a decline, but show a significant spatial variability in dissolved concentrations with lower levels in the open Western and South Eastern Mediterranean, and higher concentrations in the Black, Marmara, and Aegean Seas and Sicilian Strait. PCB and OCPs (organochlorine pesticides) concentrations in plankton were higher at lower plankton biomass, but the intensity of this trend depended on the compound hydrophobicity (K(OW)). For the more persistent PCBs and HCB, the observed dependence of POP concentrations in plankton versus biomass can be explained by interactions between air-water exchange, particle settling, and/or bioaccumulation processes, whereas degradation processes occurring in the photic zone drive the trends shown by the more labile HCHs. The results presented here provide clear evidence of the important physical and biogeochemical controls on POP occurrence in the marine environment.

  12. Influence of ocean acidification and deep water upwelling on oligotrophic plankton communities in the subtropical North Atlantic

    DEFF Research Database (Denmark)

    Taucher, Jan; Bach, Lennart T.; Boxhammer, Tim

    2017-01-01

    Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. Increasing evidence indicates that these changes-summarized by the term ocean acidification (OA)-can significantly affect marine food webs and biogeochemical...... cycles. However, current scientific knowledge is largely based on laboratory experiments with single species and artificial boundary conditions, whereas studies of natural plankton communities are still relatively rare. Moreover, the few existing community-level studies were mostly conducted in rather...... and successfully simulated a deep water upwelling event that induced a pronounced plankton bloom. Our study revealed significant effects of OA on the entire food web, leading to a restructuring of plankton communities that emerged during the oligotrophic phase, and was further amplified during the bloom...

  13. Comparative analysis of marine ecosystems: workshop on predator-prey interactions

    DEFF Research Database (Denmark)

    Bailey, Kevin M.; Ciannelli, Lorenzo; Hunsicker, Mary

    2010-01-01

    in marine ecosystems was held at the Oregon State University, Corvallis, OR, USA on 16–18 March 2010. The meeting brought together scientists from diverse fields of expertise including theoretical ecology, animal behaviour, fish and seabird ecology, statistics, fisheries science and ecosystem modelling......Climate and human influences on marine ecosystems are largely manifested by changes in predator–prey interactions. It follows that ecosystem-based management of the world's oceans requires a better understanding of food web relationships. An international workshop on predator–prey interactions...

  14. Activities of Fluconazole, Caspofungin, Anidulafungin, and Amphotericin B on Planktonic and Biofilm Candida Species Determined by Microcalorimetry

    Science.gov (United States)

    Maiolo, Elena Maryka; Furustrand Tafin, Ulrika; Borens, Olivier

    2014-01-01

    We investigated the activities of fluconazole, caspofungin, anidulafungin, and amphotericin B against Candida species in planktonic form and biofilms using a highly sensitive assay measuring growth-related heat production (microcalorimetry). C. albicans, C. glabrata, C. krusei, and C. parapsilosis were tested, and MICs were determined by the broth microdilution method. The antifungal activities were determined by isothermal microcalorimetry at 37°C in RPMI 1640. For planktonic Candida, heat flow was measured in the presence of antifungal dilutions for 24 h. Candida biofilm was formed on porous glass beads for 24 h and exposed to serial dilutions of antifungals for 24 h, and heat flow was measured for 48 h. The minimum heat inhibitory concentration (MHIC) was defined as the lowest antifungal concentration reducing the heat flow peak by ≥50% (≥90% for amphotericin B) at 24 h for planktonic Candida and at 48 h for Candida biofilms (measured also at 24 h). Fluconazole (planktonic MHICs, 0.25 to >512 μg/ml) and amphotericin B (planktonic MHICs, 0.25 to 1 μg/ml) showed higher MHICs than anidulafungin (planktonic MHICs, 0.015 to 0.5 μg/ml) and caspofungin (planktonic MHICs, 0.125 to 0.5 μg/ml). Against Candida species in biofilms, fluconazole's activity was reduced by >1,000-fold compared to its activity against the planktonic counterparts, whereas echinocandins and amphotericin B mainly preserved their activities. Fluconazole induced growth of planktonic C. krusei at sub-MICs. At high concentrations of caspofungin (>4 μg/ml), paradoxical growth of planktonic C. albicans and C. glabrata was observed. Microcalorimetry enabled real-time evaluation of antifungal activities against planktonic and biofilm Candida organisms. It can be used in the future to evaluate new antifungals and antifungal combinations and to study resistant strains. PMID:24566186

  15. Short-term effects of medetomidine on photosynthesis and protein synthesis in periphyton, epipsammon and plankton communities in relation to predicted environmental concentrations.

    Science.gov (United States)

    Ohlauson, Cecilia; Eriksson, Karl Martin; Blanck, Hans

    2012-01-01

    Medetomidine is a new antifouling substance, highly effective against barnacles. As part of a thorough ecotoxicological evaluation of medetomidine, its short-term effects on algal and bacterial communities were investigated and environmental concentrations were predicted with the MAMPEC model. Photosynthesis and bacterial protein synthesis for three marine communities, viz. periphyton, epipsammon and plankton were used as effect indicators, and compared with the predicted environmental concentrations (PECs). The plankton community showed a significant decrease in photosynthetic activity of 16% at 2 mg l⁻¹ of medetomidine, which was the only significant effect observed. PECs were estimated for a harbor, shipping lane and marina environment using three different model scenarios (MAMPEC default, Baltic and OECD scenarios). The highest PEC of 57 ng l⁻¹, generated for a marina with the Baltic scenario, was at least 10,000-fold lower than the concentration that significantly decreased photosynthetic activity. It is concluded that medetomidine does not cause any acute toxic effects on bacterial protein synthesis and only small acute effects on photosynthesis at high concentrations in marine microbial communities. It is also concluded that the hazard from medetomidine on these processes is low since the effect levels are much lower than the highest PEC.

  16. Comparative distributions of alkaline earths and Pb among tissues of marine plants and animals

    International Nuclear Information System (INIS)

    Burnett, M.W.; Settle, D.M.; Patterson, C.C.

    1978-01-01

    Lead, barium, strontium and calcium were studied by isotope dilution, clean-lab techniques in both a marine and a terrestrial ecosystem. Analyses for Pb and Ba are difficult since their concentrations range down to the ng g -1 level in plant and animal tissue. Experimental details are given. Results are presented and discussed. (U.K.)

  17. Comparative Analysis of Glycoside Hydrolases Activities from Phylogenetically Diverse Marine Bacteria of the Genus Arenibacter

    Directory of Open Access Journals (Sweden)

    Valery Mikhailov

    2013-06-01

    Full Text Available A total of 16 marine strains belonging to the genus Arenibacter, recovered from diverse microbial communities associated with various marine habitats and collected from different locations, were evaluated in degradation of natural polysaccharides and chromogenic glycosides. Most strains were affiliated with five recognized species, and some presented three new species within the genus Arenibacter. No strains contained enzymes depolymerizing polysaccharides, but synthesized a wide spectrum of glycosidases. Highly active β-N-acetylglucosaminidases and α-N-acetylgalactosaminidases were the main glycosidases for all Arenibacter. The genes, encoding two new members of glycoside hydrolyses (GH families, 20 and 109, were isolated and characterized from the genomes of Arenibacter latericius. Molecular genetic analysis using glycosidase-specific primers shows the absence of GH27 and GH36 genes. A sequence comparison with functionally-characterized GH20 and GH109 enzymes shows that both sequences are closest to the enzymes of chitinolytic bacteria Vibrio furnissii and Cellulomonas fimi of marine and terrestrial origin, as well as human pathogen Elisabethkingia meningoseptica and simbionts Akkermansia muciniphila, gut and non-gut Bacteroides, respectively. These results revealed that the genus Arenibacter is a highly taxonomic diverse group of microorganisms, which can participate in degradation of natural polymers in marine environments depending on their niche and habitat adaptations. They are new prospective candidates for biotechnological applications due to their production of unique glycosidases.

  18. Predicting plankton net community production in the Atlantic Ocean

    Science.gov (United States)

    Serret, Pablo; Robinson, Carol; Fernández, Emilio; Teira, Eva; Tilstone, Gavin; Pérez, Valesca

    2009-07-01

    We present, test and implement two contrasting models to predict euphotic zone net community production (NCP), which are based on 14C primary production (PO 14CP) to NCP relationships over two latitudinal (ca. 30°S-45°N) transects traversing highly productive and oligotrophic provinces of the Atlantic Ocean (NADR, CNRY, BENG, NAST-E, ETRA and SATL, Longhurst et al., 1995 [An estimation of global primary production in the ocean from satellite radiometer data. Journal of Plankton Research 17, 1245-1271]). The two models include similar ranges of PO 14CP and community structure, but differ in the relative influence of allochthonous organic matter in the oligotrophic provinces. Both models were used to predict NCP from PO 14CP measurements obtained during 11 local and three seasonal studies in the Atlantic, Pacific and Indian Oceans, and from satellite-derived estimates of PO 14CP. Comparison of these NCP predictions with concurrent in situ measurements and geochemical estimates of NCP showed that geographic and annual patterns of NCP can only be predicted when the relative trophic importance of local vs. distant processes is similar in both modeled and predicted ecosystems. The system-dependent ability of our models to predict NCP seasonality suggests that trophic-level dynamics are stronger than differences in hydrodynamic regime, taxonomic composition and phytoplankton growth. The regional differences in the predictive power of both models confirm the existence of biogeographic differences in the scale of trophic dynamics, which impede the use of a single generalized equation to estimate global marine plankton NCP. This paper shows the potential of a systematic empirical approach to predict plankton NCP from local and satellite-derived P estimates.

  19. Ecological dispersal barrier across the equatorial Atlantic in a migratory planktonic copepod

    Science.gov (United States)

    Goetze, Erica; Hüdepohl, Patricia T.; Chang, Chantel; Van Woudenberg, Lauren; Iacchei, Matthew; Peijnenburg, Katja T. C. A.

    2017-11-01

    Resolving the large-scale genetic structure of plankton populations is important to understanding their responses to climate change. However, few studies have reported on the presence and geographic extent of genetically distinct populations of marine zooplankton at ocean-basin scales. Using mitochondrial sequence data (mtCOI, 718 animals) from 18 sites across a basin-scale Atlantic transect (39°N-40°S), we show that populations of the dominant migratory copepod, Pleuromamma xiphias, are genetically subdivided across subtropical and tropical waters (global FST = 0.15, global ΦST = 0.21, both P marine plankton, and we suggest that this may be a dominant mechanism driving the large-scale genetic structure of zooplankton species. Our results also demonstrate the potential importance of the Atlantic equatorial province as a region of evolutionary novelty for the holoplankton.

  20. Trophic efficiency of plankton food webs: Observations from the Gulf of Mannar and the Palk Bay, Southeast Coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Anjusha, A.; Jyothibabu, R; Jagadeesan, L.; Mohan, A.P.; Sudheesh, K.; Krishna, K.; Ullas, N.; Deepak, M.P.

    This paper introduces the structure and trophic efficiency of plankton food webs in the Gulf of Mannar (GoM) and the Palk Bay (PB) - two least studied marine environments located between India and Sri Lanka. The study is based on the results...

  1. High resilience of two coastal plankton communities to 21st century seawater acidification: Evidence from microcosm studies

    DEFF Research Database (Denmark)

    Nielsen, Lasse Tor; Jakobsen, Hans Henrik; Hansen, Per Juul

    2010-01-01

    Increased free CO2 and ocean acidification are among the consequences of anthropogenic carbon emissions. Responses of marine protists to increased levels of CO2 are highly species-specific, and this has been suggested to cause an alteration in plankton species composition, community functions...

  2. Psd1 Effects on Candida albicans Planktonic Cells and Biofilms

    Directory of Open Access Journals (Sweden)

    Sónia Gonçalves

    2017-06-01

    Full Text Available Candida albicans is an important human pathogen, causing opportunistic infections. The adhesion of planktonic cells to a substrate is the first step for biofilm development. The antimicrobial peptide (AMP Psd1 is a defensin isolated from Pisum sativum seeds. We tested the effects of this AMP on C. albicans biofilms and planktonic cells, comparing its activity with amphotericin B and fluconazole. Three C. albicans variants were studied, one of them a mutant deficient in glucosylceramide synthase, conferring resistance to Psd1 antifungal action. Atomic force microscopy (AFM was used to assess morphological and biomechanical changes on fungal cells. Surface alterations, with membrane disruption and leakage of cellular contents, were observed. Cytometry assays and confocal microscopy imaging showed that Psd1 causes cell death, in a time and concentration-dependent manner. These results demonstrate Psd1 pleiotropic action against a relevant fungal human pathogen, suggesting its use as natural antimycotic agent.

  3. SAR11 Bacteria: The Most Abundant Plankton in the Oceans.

    Science.gov (United States)

    Giovannoni, Stephen J

    2017-01-03

    SAR11 is a group of small, carbon-oxidizing bacteria that reach a global estimated population size of 2.4×10 28 cells-approximately 25% of all plankton. They are found throughout the oceans but reach their largest numbers in stratified, oligotrophic gyres, which are an expanding habitat in the warming oceans. SAR11 likely had a Precambrian origin and, over geological time, evolved into the niche of harvesting labile, low-molecular-weight dissolved organic matter (DOM). SAR11 cells are minimal in size and complexity, a phenomenon known as streamlining that is thought to benefit them by lowering the material costs of replication and maximizing transport functions that are essential to competition at ultralow nutrient concentrations. One of the surprises in SAR11 metabolism is their ability to both oxidize and produce a variety of volatile organic compounds that can diffuse into the atmosphere. SAR11 cells divide slowly and lack many forms of regulation commonly used by bacterial cells to adjust to changing environmental conditions. As a result of genome reduction, they require an unusual range of nutrients, which leads to complex biochemical interactions with other plankton. The study of SAR11 is providing insight into the biogeochemistry of labile DOM and is affecting microbiology beyond marine science by providing a model for understanding the evolution and function of streamlined cells.

  4. Comparative analysis of purified Pacific and Caribbean ciguatoxin congeners and related marine toxins using a modified ELISA technique.

    Science.gov (United States)

    Campora, Cara E; Hokama, Y; Ebesu, Joanne S M

    2006-01-01

    The monoclonal antibody to ciguatoxin (CTX) produced from a hybridoma cell line was assayed for the detection of four congeners of CTX: Pacific ciguatoxin-1 (P-CTX-1), Pacific ciguatoxin-2 (P-CTX-2), Pacific ciguatoxin-3 (P-CTX-3), and Caribbean ciguatoxin-1 (C-CTX-1) and related marine toxins, including domoic acid, palytoxin, and okadaic acid, using a modified enzyme-linked immunosorbent assay (ELISA). Lower detection limits were assessed and linearity was statistically established (P<0.05) for P-CTX-1, P-CTX-2, and P-CTX-3 and C-CTX-1 at concentrations ranging from 0 to 5.00 ng, while the other marine toxins showed statistically insignificant cross-reactivities at similar concentrations. Thus, the monoclonal antibody to CTX is able to specifically detect various CTX congeners at levels comparable to those naturally occurring in ciguatoxic fish. (c) 2006 Wiley-Liss, Inc.

  5. Cultivation of seaweed Gracilaria lemaneiformis enhanced biodiversity in a eukaryotic plankton community as revealed via metagenomic analyses.

    Science.gov (United States)

    Chai, Zhao Yang; He, Zhi Li; Deng, Yun Yan; Yang, Yu Feng; Tang, Ying Zhong

    2018-02-01

    Plankton diversity reflects the quality and health of waters and should be monitored as a critical feature of marine ecosystems. This study applied a pair of 28S rRNA gene-specific primers and pyrosequencing to assess the effects of large-scale cultivation of the seaweed Gracilaria lemaneiformis on the biodiversity of eukaryotic plankton community in the coastal water of Guangdong, China. With 1 million sequences (2,221 operational taxonomic units [OTUs]) obtained from 51 samples, we found that the biodiversity of eukaryotic plankton community was significantly higher in the seaweed cultivation area than that in the nearby control area as reflected in OTU richness, evenness (Shannon-Wiener index) and dominance (Simpson index) for total plankton community and its four subcategories when Gracilaria biomass reached the maximum, while no such a significant difference was observed before seaweed inoculation. Our laboratory experiment using an artificial phytoplankton community of nine species observed the same effects of Gracilaria exposure. Principal component analysis and principal coordinates analysis showed the plankton community structure in cultivation area markedly differed from the control area when Gracilaria biomass reached its maximum. Redundancy analysis showed that G. lemaneiformis was the critical factor in controlling the dynamics of eukaryotic plankton communities in the studied coastal ecosystem. Our results explicitly demonstrated G. lemaneiformis cultivation could enhance biodiversity of plankton community via allelopathy, which prevents one or several plankton species from blooming and consequently maintains a relatively higher biodiversity. Our study provided further support for using large-scale G. lemaneiformis cultivation as an effective approach for improving costal ecosystem health. © 2018 John Wiley & Sons Ltd.

  6. Crustacean Larvae-Vision in the Plankton.

    Science.gov (United States)

    Cronin, Thomas W; Bok, Michael J; Lin, Chan

    2017-11-01

    We review the visual systems of crustacean larvae, concentrating on the compound eyes of decapod and stomatopod larvae as well as the functional and behavioral aspects of their vision. Larval compound eyes of these macrurans are all built on fundamentally the same optical plan, the transparent apposition eye, which is eminently suitable for modification into the abundantly diverse optical systems of the adults. Many of these eyes contain a layer of reflective structures overlying the retina that produces a counterilluminating eyeshine, so they are unique in being camouflaged both by their transparency and by their reflection of light spectrally similar to background light to conceal the opaque retina. Besides the pair of compound eyes, at least some crustacean larvae have a non-imaging photoreceptor system based on a naupliar eye and possibly other frontal eyes. Larval compound-eye photoreceptors send axons to a large and well-developed optic lobe consisting of a series of neuropils that are similar to those of adult crustaceans and insects, implying sophisticated analysis of visual stimuli. The visual system fosters a number of advanced and flexible behaviors that permit crustacean larvae to survive extended periods in the plankton and allows them to reach acceptable adult habitats, within which to metamorphose. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  7. Fossil-based comparative analyses reveal ancient marine ancestry erased by extinction in ray-finned fishes.

    Science.gov (United States)

    Betancur-R, Ricardo; Ortí, Guillermo; Pyron, Robert Alexander

    2015-05-01

    The marine-freshwater boundary is a major biodiversity gradient and few groups have colonised both systems successfully. Fishes have transitioned between habitats repeatedly, diversifying in rivers, lakes and oceans over evolutionary time. However, their history of habitat colonisation and diversification is unclear based on available fossil and phylogenetic data. We estimate ancestral habitats and diversification and transition rates using a large-scale phylogeny of extant fish taxa and one containing a massive number of extinct species. Extant-only phylogenetic analyses indicate freshwater ancestry, but inclusion of fossils reveal strong evidence of marine ancestry in lineages now restricted to freshwaters. Diversification and colonisation dynamics vary asymmetrically between habitats, as marine lineages colonise and flourish in rivers more frequently than the reverse. Our study highlights the importance of including fossils in comparative analyses, showing that freshwaters have played a role as refuges for ancient fish lineages, a signal erased by extinction in extant-only phylogenies. © 2015 John Wiley & Sons Ltd/CNRS.

  8. Plankton bloom controlled by horizontal stirring

    Science.gov (United States)

    McKiver, W.; Neufeld, Z.; Scheuring, I.

    2009-10-01

    Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass.

  9. Comparing Ecological and Genetic Diversity Within the Marine Diatom Genus Pseudo-nitzschia: A Multiregional Synthesis

    Science.gov (United States)

    Hubbard, K.; Bruzek, S.

    2016-02-01

    The globally distributed marine diatom genus Pseudo-nitzschia consists of approximately 40 species, more than half of which occur in US coastal waters. Here, sensitive genetic tools targeting a variable portion of the internal transcribed spacer 1 (ITS1) region of the rRNA gene were used to assess Pseudo-nitzschia spp. diversity in more than 600 environmental DNA samples collected from US Atlantic, Pacific, and Gulf of Mexico waters. Community-based approaches employed genus-specific primers for environmental DNA fingerprinting and targeted sequencing. For the Gulf of Mexico samples especially, a nested PCR approach (with or without degenerate primers) improved resolution of species diversity. To date, more than 40 unique ITS1 amplicon sizes have been repeatedly observed in ITS1 fingerprints. Targeted sequencing of environmental DNA as well as single chains isolated from live samples indicate that many of these represent novel and known inter- and intra-specific Pseudo-nitzschia diversity. A few species (e.g., P. pungens, P. cuspidata) occur across all three regions, whereas other species and intraspecific variants occurred at local to regional spatial scales only. Generally, species frequently co-occur in complex assemblages, and transitions in Pseudo-nitzschia community composition occur seasonally, prior to bloom initiation, and across (cross-shelf, latitudinal, and vertical) environmental gradients. These observations highlight the dynamic nature of diatom community composition in the marine environment and the importance of classifying diversity at relevant ecological and/or taxonomic scales.

  10. Spatial Distribution of Viruses Associated with Planktonic and Attached Microbial Communities in Hydrothermal Environments

    Science.gov (United States)

    Nunoura, Takuro; Kazama, Hiromi; Noguchi, Takuroh; Inoue, Kazuhiro; Akashi, Hironori; Yamanaka, Toshiro; Toki, Tomohiro; Yamamoto, Masahiro; Furushima, Yasuo; Ueno, Yuichiro; Yamamoto, Hiroyuki; Takai, Ken

    2012-01-01

    Viruses play important roles in marine surface ecosystems, but little is known about viral ecology and virus-mediated processes in deep-sea hydrothermal microbial communities. In this study, we examined virus-like particle (VLP) abundances in planktonic and attached microbial communities, which occur in physical and chemical gradients in both deep and shallow submarine hydrothermal environments (mixing waters between hydrothermal fluids and ambient seawater and dense microbial communities attached to chimney surface areas or macrofaunal bodies and colonies). We found that viruses were widely distributed in a variety of hydrothermal microbial habitats, with the exception of the interior parts of hydrothermal chimney structures. The VLP abundance and VLP-to-prokaryote ratio (VPR) in the planktonic habitats increased as the ratio of hydrothermal fluid to mixing water increased. On the other hand, the VLP abundance in attached microbial communities was significantly and positively correlated with the whole prokaryotic abundance; however, the VPRs were always much lower than those for the surrounding hydrothermal waters. This is the first report to show VLP abundance in the attached microbial communities of submarine hydrothermal environments, which presented VPR values significantly lower than those in planktonic microbial communities reported before. These results suggested that viral lifestyles (e.g., lysogenic prevalence) and virus interactions with prokaryotes are significantly different among the planktonic and attached microbial communities that are developing in the submarine hydrothermal environments. PMID:22210205

  11. SEAMAP 2015 Fall Plankton Survey (PC1504, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2015 Fall Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  12. SEAMAP 2013 Fall Plankton Survey (PC1305, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2013 Fall Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  13. SEAMAP Fall 2014 Plankton Survey (GU1405, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2014 Fall Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  14. SEAMAP 2013 Fall Plankton Survey (PC1305, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2013 Fall Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  15. SEAMAP Spring 2016 Plankton Survey (R21601, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2016 Spring Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  16. SEAMAP Spring 2015 Plankton Survey (GU1501, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the 2015 Spring Plankton Survey, plankton samples were collected from a systematic grid of stations to assess distribution, occurrence and abundance of the...

  17. Nesting phenology of marine turtles: insights from a regional comparative analysis on green turtle (Chelonia mydas.

    Directory of Open Access Journals (Sweden)

    Mayeul Dalleau

    Full Text Available Changes in phenology, the timing of seasonal activities, are among the most frequently observed responses to environmental disturbances and in marine species are known to occur in response to climate changes that directly affects ocean temperature, biogeochemical composition and sea level. We examined nesting seasonality data from long-term studies at 8 green turtle (Chelonia mydas rookeries that include 21 specific nesting sites in the South-West Indian Ocean (SWIO. We demonstrated that temperature drives patterns of nesting seasonality at the regional scale. We found a significant correlation between mean annual Sea Surface Temperature (SST and dates of peak nesting with rookeries exposed to higher SST having a delayed nesting peak. This supports the hypothesis that temperature is the main factor determining peak nesting dates. We also demonstrated a spatial synchrony in nesting activity amongst multiple rookeries in the northern part of the SWIO (Aldabra, Glorieuses, Mohéli, Mayotte but not with the eastern and southern rookeries (Europa, Tromelin, differences which could be attributed to females with sharply different adult foraging conditions. However, we did not detect a temporal trend in the nesting peak date over the study period or an inter-annual relation between nesting peak date and SST. The findings of our study provide a better understanding of the processes that drive marine species phenology. The findings will also help to predict their ability to cope with climate change and other environmental perturbations. Despite demonstrating this spatial shift in nesting phenology, no trend in the alteration of nesting dates over more than 20 years was found.

  18. Dispersal similarly shapes both population genetics and community patterns in the marine realm

    KAUST Repository

    Chust, Guillem

    2016-06-27

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns.

  19. Dispersal similarly shapes both population genetics and community patterns in the marine realm

    Science.gov (United States)

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Fernández de Puelles, María L.; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G.; Mozetič, Patricija; Vandepitte, Leen; Veríssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-06-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns.

  20. Dispersal similarly shapes both population genetics and community patterns in the marine realm

    KAUST Repository

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Ferná ndez de Puelles, Marí a L.; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G.; Mozetič, Patricija; Vandepitte, Leen; Verí ssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-01-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns.

  1. Composition of planktonic organisms and its associated physico ...

    African Journals Online (AJOL)

    Composition of plankton communities in two ponds at African Regional Agriculture Centre (ARAC) Aluu, Port Harcourt was undertaken between May and June 2004, to assess the composition, relative abundance and distribution of plankton. The diversity of plankton was poor. Twenty-eight taxa representing four (4) families ...

  2. Planktonic interactions and chaotic advection in Langmuir circulation

    DEFF Research Database (Denmark)

    Bees, Martin Alan; Mezic, I.; McGlade, J.

    1998-01-01

    The role of unsteady laminar flows for planktonic communities is investigated. Langmuir circulation is used, as a typical medium-scale structure, to illustrate mechanisms for the generation of plankton patches. Two behaviours are evident: chaotic regions that help to spread plankton and locally...

  3. Decomposition in pelagic marine ecosytems

    International Nuclear Information System (INIS)

    Lucas, M.I.

    1986-01-01

    During the decomposition of plant detritus, complex microbial successions develop which are dominated in the early stages by a number of distinct bacterial morphotypes. The microheterotrophic community rapidly becomes heterogenous and may include cyanobacteria, fungi, yeasts and bactivorous protozoans. Microheterotrophs in the marine environment may have a biomass comparable to that of all other heterotrophs and their significance as a resource to higher trophic orders, and in the regeneration of nutrients, particularly nitrogen, that support 'regenerated' primary production, has aroused both attention and controversy. Numerous methods have been employed to measure heterotrophic bacterial production and activity. The most widely used involve estimates of 14 C-glucose uptake; the frequency of dividing cells; the incorporation of 3 H-thymidine and exponential population growth in predator-reduced filtrates. Recent attempts to model decomposition processes and C and N fluxes in pelagic marine ecosystems are described. This review examines the most sensitive components and predictions of the models with particular reference to estimates of bacterial production, net growth yield and predictions of N cycling determined by 15 N methodology. Directed estimates of nitrogen (and phosphorus) flux through phytoplanktonic and bacterioplanktonic communities using 15 N (and 32 P) tracer methods are likely to provide more realistic measures of nitrogen flow through planktonic communities

  4. Taxonomic and Functional Microbial Signatures of the Endemic Marine Sponge Arenosclera brasiliensis

    Science.gov (United States)

    Trindade-Silva, Amaro E.; Rua, Cintia; Silva, Genivaldo G. Z.; Dutilh, Bas E.; Moreira, Ana Paula B.; Edwards, Robert A.; Hajdu, Eduardo; Lobo-Hajdu, Gisele; Vasconcelos, Ana Tereza; Berlinck, Roberto G. S.; Thompson, Fabiano L.

    2012-01-01

    The endemic marine sponge Arenosclera brasiliensis (Porifera, Demospongiae, Haplosclerida) is a known source of secondary metabolites such as arenosclerins A-C. In the present study, we established the composition of the A. brasiliensis microbiome and the metabolic pathways associated with this community. We used 454 shotgun pyrosequencing to generate approximately 640,000 high-quality sponge-derived sequences (∼150 Mb). Clustering analysis including sponge, seawater and twenty-three other metagenomes derived from marine animal microbiomes shows that A. brasiliensis contains a specific microbiome. Fourteen bacterial phyla (including Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Cloroflexi) were consistently found in the A. brasiliensis metagenomes. The A. brasiliensis microbiome is enriched for Betaproteobacteria (e.g., Burkholderia) and Gammaproteobacteria (e.g., Pseudomonas and Alteromonas) compared with the surrounding planktonic microbial communities. Functional analysis based on Rapid Annotation using Subsystem Technology (RAST) indicated that the A. brasiliensis microbiome is enriched for sequences associated with membrane transport and one-carbon metabolism. In addition, there was an overrepresentation of sequences associated with aerobic and anaerobic metabolism as well as the synthesis and degradation of secondary metabolites. This study represents the first analysis of sponge-associated microbial communities via shotgun pyrosequencing, a strategy commonly applied in similar analyses in other marine invertebrate hosts, such as corals and algae. We demonstrate that A. brasiliensis has a unique microbiome that is distinct from that of the surrounding planktonic microbes and from other marine organisms, indicating a species-specific microbiome. PMID:22768320

  5. Comparative biogeochemical behaviors of iron-55 and stable iron in the marine environment

    International Nuclear Information System (INIS)

    Weimer, W.C.; Langford, J.C.; Jenkins, C.E.

    1978-01-01

    Studies of atmospheric aerosols have demonstrated that much of the 55 Fe associated with the aerosol input to the oceans is present as either an amorphous or hydrous iron oxide or as very small particulate species attached to the surfaces of the large aerosol particles. By comparison, nearly all of the stable iron is bound in the mineral phase of aerosol particles. This difference in the chemical and physical forms of the radioactive and stable iron isotopes results in the 55 Fe being more biologically available than is the stable iron. This difference in availability is responsible for the transfer of a much higher specific activity 55 Fe to certain ocean organisms and man relative to the specific activity of the total aerosol or of sea water. This differential biological uptake of the radioactive element and its stable element counterpart points out that natural levels of stable elements in the marine environment may not effectively dilute radioelements or other stable elements of anthropogenic sources. The effectiveness of dilution by natural sources depends on the chemical and physical forms of the materials in both the source terms and the receiving environments. The large difference in specific activities of 55 Fe in aerosols and sea water relative to ocean organisms reflects the independent behaviors of 55 Fe and stable iron

  6. Factors affecting egg ratios in planktonic rotifers

    NARCIS (Netherlands)

    Sarma, S.S.S.; Gulati, R.D.; Nandini, S.

    2005-01-01

    Edmondson’s egg ratio (number of amictic eggs per female) is an important life history variable, which has been in wide use to understand and predict patterns of population growth in planktonic rotifers under field conditions. It is also useful as an indicator of the health of rotifers under culture

  7. Standard filtration practices may significantly distort planktonic microbial diversity estimates

    Directory of Open Access Journals (Sweden)

    Cory Cruz Padilla

    2015-06-01

    Full Text Available Fractionation of biomass by filtration is a standard method for sampling planktonic microbes. It is unclear how the taxonomic composition of filtered biomass changes depending on sample volume. Using seawater from a marine oxygen minimum zone, we quantified the 16S rRNA gene composition of biomass on a prefilter (1.6 μm pore-size and a downstream 0.2 μm filter over sample volumes from 0.05 to 5 L. Significant community shifts occurred in both filter fractions, and were most dramatic in the prefilter community. Sequences matching Vibrionales decreased from ~40-60% of prefilter datasets at low volumes (0.05-0.5 L to less than 5% at higher volumes, while groups such at the Chromatiales and Thiohalorhabdales followed opposite trends, increasing from minor representation to become the dominant taxa at higher volumes. Groups often associated with marine particles, including members of the Deltaproteobacteria, Planctomycetes and Bacteroidetes, were among those showing the greatest increase with volume (4 to 27-fold. Taxon richness (97% similarity clusters also varied significantly with volume, and in opposing directions depending on filter fraction, highlighting potential biases in community complexity estimates. These data raise concerns for studies using filter fractionation for quantitative comparisons of aquatic microbial diversity, for example between free-living and particle-associated communities.

  8. Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean.

    Science.gov (United States)

    McMahon, Kelton W; McCarthy, Matthew D; Sherwood, Owen A; Larsen, Thomas; Guilderson, Thomas P

    2015-12-18

    Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ(13)C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations. Copyright © 2015, American Association for the Advancement of Science.

  9. Quantification and localization of trace metals in natural plankton using a synchrotron x-ray fluorescence microprobe

    International Nuclear Information System (INIS)

    Twining, B. S.; Baines, S. B.; Fisher, N. S.; Jacobsen, C.; Maser, J.; State Univ. of New York at Stony Brook

    2003-01-01

    The accumulation of trace metals by planktonic protists influences the growth of primary producers, metal biogeochemical cycling, and metal bioaccumulation in aquatic food chains. Despite their importance, unequivocal measurements of trace element concentrations in individual plankton cells have not been possible to date. We have used the 2-ID-E side-branch hard x-ray microprobe at the Advanced Photon Source to measure trace elements in individual marine plankton cells. This microprobe employs zoneplate optics to produce the sub-micron spatial resolution and low background fluorescence required to produce trace element maps of planktonic protist cells ranging in size from 3 to >50 (micro)m. We have developed preservation, rinsing, and mounting protocols that remove most of the salt from our marine samples, thus simplifying the identification of unknown cells and reducing high Cl-related background fluorescence. We have also developed spectral modeling techniques that account for the frequent overlap of adjacent fluorescence peaks and non-uniform detector response. Finally, we have used parallel soft x-ray transmission and epifluorescence microscopy images to estimate C normalized trace element concentrations, identify functional cell types (e.g., photosynthetic vs. non-photosynthetic), and correlate cell structures with spatial patterns in trace element fluorescence

  10. Stratification of archaeal membrane lipids in the ocean and implications for adaptation and chemotaxonomy of planktonic archaea.

    Science.gov (United States)

    Zhu, Chun; Wakeham, Stuart G; Elling, Felix J; Basse, Andreas; Mollenhauer, Gesine; Versteegh, Gerard J M; Könneke, Martin; Hinrichs, Kai-Uwe

    2016-12-01

    Membrane lipids of marine planktonic archaea have provided unique insights into archaeal ecology and paleoceanography. However, past studies of archaeal lipids in suspended particulate matter (SPM) and sediments mainly focused on a small class of fully saturated glycerol dibiphytanyl glycerol tetraether (GDGT) homologues identified decades ago. The apparent low structural diversity of GDGTs is in strong contrast to the high diversity of metabolism and taxonomy among planktonic archaea. Furthermore, adaptation of archaeal lipids in the deep ocean remains poorly constrained. We report the archaeal lipidome in SPM from diverse oceanic regimes. We extend the known inventory of planktonic archaeal lipids to include numerous unsaturated archaeal ether lipids (uns-AELs). We further reveal (i) different thermal regulations and polar headgroup compositions of membrane lipids between the epipelagic (≤ 100 m) and deep (>100 m) populations of archaea, (ii) stratification of unsaturated GDGTs with varying redox conditions, and (iii) enrichment of tetra-unsaturated archaeol and fully saturated GDGTs in epipelagic and deep oxygenated waters, respectively. Such stratified lipid patterns are consistent with the typical distribution of archaeal phylotypes in marine environments. We, thus, provide an ecological context for GDGT-based paleoclimatology and bring about the potential use of uns-AELs as biomarkers for planktonic Euryarchaeota. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Marine Benthic Invertebrates in Mamala Bay, Oahu, Hawaii 1994 (NODC Accession 9900151)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Planktonic larval stages of many benthic marine invertebrates are especially susceptible to environmental stress, such as the presence of pollution. Recruitment of...

  12. Comparative Omics and Trait Analyses of Marine Pseudoalteromonas Phages Advance the Phage OTU Concept

    Directory of Open Access Journals (Sweden)

    Melissa B. Duhaime

    2017-07-01

    considered viral niches, while host ranges and infection efficiencies are tracked as viral traits. Quantitative host range assays revealed conserved traits within virus OTUs that break down between OTUs, suggesting the defined units capture niche and fitness differentiation. Together these analyses provide a foundation for model system-based hypothesis testing that will improve our understanding of marine copiotrophs, as well as phage–host interactions on the ocean particles and aggregates where Pseudoalteromonas thrive.

  13. Mesh size effects on assessments of planktonic hydrozoan abundance and assemblage structure

    Science.gov (United States)

    Nogueira Júnior, Miodeli; Pukanski, Luis Eduardo de M.; Souza-Conceição, José M.

    2015-04-01

    The choice of appropriate mesh-size is paramount to accurately quantify planktonic assemblages, however there is no such information available for hydrozoans. Here planktonic hydrozoan abundance and assemblage structure were compared using 200 and 500 μm meshes at Babitonga estuary (S Brazil), throughout a year cycle. Species richness and Shannon-Wiener diversity were higher in the 200 μm mesh, while evenness was typically higher in the 500 μm. Assemblage structure was significantly different between meshes (PERMANOVA, P 8 mm in October. These results suggest that both meshes have their drawbacks and the best choice would depend on the objectives of each study. Nevertheless species richness, total abundances and most taxa were better represented by the 200 μm mesh, suggesting that it is more appropriate to quantitatively sample planktonic hydrozoan assemblages.

  14. A resource-based game theoretical approach for the paradox of the plankton

    Directory of Open Access Journals (Sweden)

    Weini Huang

    2016-08-01

    Full Text Available The maintenance of species diversity is a central focus in ecology. It is not rare to observe more species than the number of limiting resources, especially in plankton communities. However, such high species diversity is hard to achieve in theory under the competitive exclusion principles, known as the plankton paradox. Previous studies often focus on the coexistence of predefined species and ignore the fact that species can evolve. We model multi-resource competitions using evolutionary games, where the number of species fluctuates under extinction and the appearance of new species. The interspecific and intraspecific competitions are captured by a dynamical payoff matrix, which has a size of the number of species. The competition strength (payoff entries is obtained from comparing the capability of species in consuming resources, which can change over time. This allows for the robust coexistence of a large number of species, providing a possible solution to the plankton paradox.

  15. A resource-based game theoretical approach for the paradox of the plankton.

    Science.gov (United States)

    Huang, Weini; de Araujo Campos, Paulo Roberto; Moraes de Oliveira, Viviane; Fagundes Ferrreira, Fernando

    2016-01-01

    The maintenance of species diversity is a central focus in ecology. It is not rare to observe more species than the number of limiting resources, especially in plankton communities. However, such high species diversity is hard to achieve in theory under the competitive exclusion principles, known as the plankton paradox. Previous studies often focus on the coexistence of predefined species and ignore the fact that species can evolve. We model multi-resource competitions using evolutionary games, where the number of species fluctuates under extinction and the appearance of new species. The interspecific and intraspecific competitions are captured by a dynamical payoff matrix, which has a size of the number of species. The competition strength (payoff entries) is obtained from comparing the capability of species in consuming resources, which can change over time. This allows for the robust coexistence of a large number of species, providing a possible solution to the plankton paradox.

  16. Resting Stage of Plankton Diversity from Singapore Coastal Water: Implications for Harmful Algae Blooms and Coastal Management

    Science.gov (United States)

    Trottet, Aurore; Wilson, Bryan; Sew Wei Xin, Genevieve; George, Christaline; Casten, Lemuel; Schmoker, Claire; Rawi, Nurul Syazana Binte Modh; Chew Siew, Moon; Larsen, Ole; Eikaas, Hans S.; Tun, Karenne; Drillet, Guillaume

    2018-02-01

    Resting strategies of planktonic organisms are important for the ecological processes of coastal waters and their impacts should be taken into consideration in management of water bodies used by multiple industries. We combined different approaches to evaluate the importance of resting stages in Singapore coastal waters. We used molecular approaches to improve the knowledge on Singapore biodiversity, we sampled and extracted cysts from sediments to evaluate the density of resting stages in Johor Strait, and we compared systematically information on Singapore planktonic biodiversity to existing published information on resting stages from these reported organisms. This is the first study evaluating the importance of resting stages in Singapore waters. Above 120 species reported in Singapore are known to produce resting stages though no previous work has ever been done to evaluate the importance of these strategies in these waters. The results from the resting stage survey confirmed 0.66 to 5.34 cyst g-1 dry weight sediment were present in the Johor Strait suggesting that cysts may be flushed by tidal currents into and out of the strait regularly. This also suggest that the blooms occurring in Singapore are likely due to secondary growth of Harmful Algae Bloom species in the water rather than from direct germination of cysts from sediment. Finally, we discuss the importance of these resting eggs for three main national industries in Singapore (shipping, marine aquaculture and provision of drinking water through seawater desalination). We argue that this study will serve as a baseline for some of the future management of Singapore waters.

  17. A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)

    Science.gov (United States)

    Nabi, Md. Nurun; Brown, Richard J.; Ristovski, Zoran; Hustad, Johan Einar

    2012-09-01

    The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

  18. Are Mussels Always the Best Bioindicators? Comparative Study on Biochemical Responses of Three Marine Invertebrate Species to Chronic Port Pollution.

    Science.gov (United States)

    Laitano, María V; Fernández-Gimenez, Analía V

    2016-07-01

    Bivalves have traditionally been considered good bioindicators due to their sensitivity to pollution, among other features. This characteristic is shared by several other non-bivalve species as well, though studies in this respect remain scarce. This work aims to compare biomarker sensitivity to chronic port pollution among three intertidal invertebrate species with good bioindicator characteristics. Mussels' immunological (phenoloxidase and peroxidases) and biotransformation (glutathione-S-transferase) responses were contrasted against those of limpets and barnacles. The three species under study evidenced activity of all the enzymes measured, although with differences. Barnacle Balanus glandula was the most sensitive species showing pollution modulation of the three enzymes, which suggests that mussels would not always be the best bioindicator species among marine invertebrates depending on the responses that are assessed.

  19. Smoothing a Piecewise-Smooth: An Example from Plankton Population Dynamics

    DEFF Research Database (Denmark)

    Piltz, Sofia Helena

    2016-01-01

    In this work we discuss a piecewise-smooth dynamical system inspired by plankton observations and constructed for one predator switching its diet between two different types of prey. We then discuss two smooth formulations of the piecewise-smooth model obtained by using a hyperbolic tangent funct...... function and adding a dimension to the system. We compare model behaviour of the three systems and show an example case where the steepness of the switch is determined from a comparison with data on freshwater plankton....

  20. Study the Seasonal Variability of Plankton and Forage Fish in the Gulf of Khambhat Using Npzfd Model

    Science.gov (United States)

    Kumar, V.; Kumar, S.

    2016-02-01

    Numerical modelling of marine ecology exploits several assumptions and it is indeed quite challenging to include marine ecological phenomena into a mathematical framework with too many unknown parameters. The governing ordinary differential equations represent the interaction of the biological and chemical processes in a marine environment. The key concern in the development of a numerical models are parameterizations based on output, viz., mathematical modelling of ecological system mainly depends on parameters and its variations. Almost, all constituents of each trophic level of marine food web are depended on phytoplankton, which are mostly influenced by initial slope of P-I curve and nutrient stock in the study domain. Whereas, the earlier plankton dynamic models rarely include a compartment of small fish and as an agent in zooplankton mortality, which is most important for the modelling of higher trophic level of marine species. A compartment of forage fish in the modelling of plankton dynamics has been given more realistic mortality rates of plankton, viz., they feed upon phytoplankton and zooplankton. The inclusion of an additional compartment increases complexity of earlier plankton dynamics model as it introduces additional unknown parameters, which has been specified for performing the numerical simulations.As a case study we applied our analysis to explain the aquatic ecology of Gulf of Khambhat (19o 48' N - 22o20' N, 65o E - 72o40' E), west coast of India, which has rich bio-diversity and a high productive area in the form of plankton and forage fish. It has elevated turbidity and varying geography location, viz., one of the regions among world's ocean with high biological productivity.The model presented in this study is able to bring out the essential features of the observed data; that includes the bimodal oscillations in the observed data, monthly mean chlorophyll-a in the SeaWiFs/MODIS Aqua data and in-situ data of plankton. The additional

  1. Effects of Pollutants on Marine Life Probed

    Science.gov (United States)

    Chemical and Engineering News, 1973

    1973-01-01

    Discusses research activities conducted by scientists from the United State of America, Canada, and the United Kingdom to determine the long-term effects on natural marine ecosystems, especially plankton communities, of such pollutants as heavy metals, synthetic hydrocarbons, and petroleum hydrocarbons. (CC)

  2. Ecological roulette: the global transport of nonindigenous marine organisms.

    Science.gov (United States)

    Cariton, J T; Geller, J B

    1993-07-02

    Ocean-going ships carry, as ballast, seawater that is taken on in port and released at subsequent ports of call. Plankton samples from Japanese ballast water released in Oregon contained 367 taxa. Most taxa with a planktonic phase in their life cycle were found in ballast water, as were all major marine habitat and trophic groups. Transport of entire coastal planktonic assemblages across oceanic barriers to similar habitats renders bays, estuaries, and inland waters among the most threatened ecosystems in the world. Presence of taxonomically difficult or inconspicuous taxa in these samples suggests that ballast water invasions are already pervasive.

  3. How well does the Continuous Plankton Recorder (CPR) sample zooplankton? A comparison with the Longhurst Hardy Plankton Recorder (LHPR) in the northeast Atlantic

    Science.gov (United States)

    Richardson, Anthony J.; John, Eurgain H.; Irigoien, Xabier; Harris, Roger P.; Hays, Graeme C.

    2004-09-01

    The Continuous Plankton Recorder (CPR) survey has collected data on basin-scale zooplankton abundance in the North Atlantic since the 1930s. These data have been used in many studies to elucidate seasonal patterns and long-term change in plankton populations, as well as more recently to validate ecosystem models. There has, however, been relatively little comparison of the data from the CPR with that from other samplers. In this study we compare zooplankton abundance estimated from the CPR in the northeast Atlantic with near-surface samples collected by a Longhurst-Hardy Plankton Recorder (LHPR) at Ocean Weather Station India (59°N, 19°W) between 1971 and 1975. Comparisons were made for six common copepods in the region: Acartia clausi, Calanus finmarchicus, Euchaeta norvegica, Metridia lucens, Oithona sp., and Pleuromamma robusta. Seasonal cycles based on CPR data were similar to those recorded by the LHPR. Differences in absolute abundances were apparent, however, with the CPR underestimating abundances by a factor of between 5 and 40, with the exception of A. clausi. Active avoidance by zooplankton is thought to be responsible. This avoidance is species specific, so that care must be taken describing communities, as the CPR emphasises those species that are preferentially caught, a problem common to many plankton samplers.

  4. Methodology for single-cell genetic analysis of planktonic foraminifera for studies of protist diversity and evolution

    Directory of Open Access Journals (Sweden)

    Agnes Katharina Maria Weiner

    2016-12-01

    Full Text Available Single-cell genetic analysis is an essential method to investigate the biodiversity and evolutionary ecology of marine protists. In protist groups that do not reproduce under laboratory conditions, this approach provides the only means to directly associate molecular sequences with cell morphology. The resulting unambiguous taxonomic identification of the DNA sequences is a prerequisite for barcoding and analyses of environmental metagenomic data. Extensive single-cell genetic studies have been carried out on planktonic foraminifera over the past 20 years to elucidate their phylogeny, cryptic diversity, biogeography and the relationship between genetic and morphological variability. In the course of these investigations, it has become evident that genetic analysis at the individual specimen level is confronted by innumerable challenges ranging from the negligible amount of DNA present in the single cell to the substantial amount of DNA contamination introduced by endosymbionts or food particles. Consequently, a range of methods has been developed and applied throughout the years for the genetic analysis of planktonic foraminifera in order to enhance DNA amplification success rates. Yet, the description of these methods in the literature rarely occurred with equivalent levels of detail and the different approaches have never been compared in terms of their efficiency and reproducibility. Here, aiming at a standardization of methods, we provide a comprehensive review of all methods that have been employed for the single-cell genetic analysis of planktonic foraminifera. We compile data on success rates of DNA amplification and use these to evaluate the effects of key parameters associated with the methods of sample collection, storage and extraction of single-cell DNA. We show that the chosen methods influence the success rates of single-cell genetic studies, but the differences between them are not sufficient to hinder comparisons between studies

  5. TOF-SIMS characterization of planktonic foraminifera

    International Nuclear Information System (INIS)

    Vering, G.; Crone, C.; Bijma, J.; Arlinghaus, H.F.

    2003-01-01

    Oceanic sediment properties that are closely related to former environmental (e.g. climatic) parameters are called 'proxies'. Planktonic foraminifera are small protists which make up part of the plankton. Certain element concentrations, element ratios and isotopic ratios of their calcite shell found in the sediment can be used as proxies reflecting the state of the ocean during the life of the animal; they supply useful information for the reconstruction of environmental parameters. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to examine the inner and outer part of foraminiferal shells, as well as foraminiferal shells dissolved in HCl. High resolution elemental images and mass spectra were obtained from the foraminifera. The data show that TOF-SIMS is a useful technique for determining the elemental distribution and for measuring isotope ratios such as δ 11 B with high precision in a single foraminiferal shell

  6. TOF-SIMS characterization of planktonic foraminifera

    Energy Technology Data Exchange (ETDEWEB)

    Vering, G.; Crone, C.; Bijma, J.; Arlinghaus, H.F

    2003-01-15

    Oceanic sediment properties that are closely related to former environmental (e.g. climatic) parameters are called 'proxies'. Planktonic foraminifera are small protists which make up part of the plankton. Certain element concentrations, element ratios and isotopic ratios of their calcite shell found in the sediment can be used as proxies reflecting the state of the ocean during the life of the animal; they supply useful information for the reconstruction of environmental parameters. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to examine the inner and outer part of foraminiferal shells, as well as foraminiferal shells dissolved in HCl. High resolution elemental images and mass spectra were obtained from the foraminifera. The data show that TOF-SIMS is a useful technique for determining the elemental distribution and for measuring isotope ratios such as {delta}{sup 11}B with high precision in a single foraminiferal shell.

  7. A comparative analysis of diffusion and transport models applying to releases in the marine environment

    International Nuclear Information System (INIS)

    Mejon, M.J.

    1984-05-01

    This study is a contribution to the development of methodologies allowing to assess the radiological impact of liquid effluent releases from nuclear power plants. It first concerns hydrodynamics models and their applications to the North sea, which is of great interest to the European Community. Starting from basic equations of geophysical fluid mechanics, the assumptions made at each step in order to simplifly resolution are analysed and commented. The results published on the application of the Liege University models (NIHOUL, RONDAY et al.) are compared to observations both on tides and tempests and residual circulation which is responsible for the long-terme transport of pollutants. The results for residual circulation compare satisfactorily, and the expected accuracy of the other models is indicated. A dispersion model by the same authors is then studied with a numerical integration method using a moving grid. Others models (Laboratoire National d'Hydraulique, EDF) used for the Channel, are also presented [fr

  8. Evaluation of two autoinducer-2 quantification methods for application in marine environments

    KAUST Repository

    Wang, Tian-Nyu

    2018-02-11

    This study evaluated two methods, namely high performance liquid chromatography with fluorescence detection (HPLC-FLD) and Vibrio harveyi BB170 bioassay, for autoinducer-2 (AI-2) quantification in marine samples. Using both methods, the study also investigated the stability of AI-2 in varying pH, temperature and media, as well as quantified the amount of AI-2 signals in marine samples.HPLC-FLD method showed a higher level of reproducibility and precision compared to V. harveyi BB170 bioassay. Alkaline pH > 8 and high temperature (> 37°C) increased the instability of AI-2. The AI-2 concentrations in seawater were low, ca. 3.2-27.6 pmol l-1 whereas 8- week old marine biofilm grew on an 18.8 cm2 substratum accumulated ca. 0.207 nmol of AI-2.Both methods have pros and cons for AI-2 quantification in marine samples. Regardless, both methods reported a ubiquitous presence of AI-2 in both planktonic and biomass fractions of seawater, as well as in marine biofilm.In this study, AI-2 signals were for the first time enumerated in marine samples to reveal the ubiquitous presence of AI-2 in this environment. The findings suggest a possible role of AI-2 in biofilm formation in marine environment, and the contribution of AI-2 in biofilm-associated problems such as biofouling and biocorrosion. This article is protected by copyright. All rights reserved.

  9. Estimates of zooplankton abundance and size distribution with the Optical Plankton Counter (OPC)

    DEFF Research Database (Denmark)

    Wieland, Kai; Petersen, D.; Schnack, D.

    1997-01-01

    The capability of the Optical Plankton Count er (OPC) to examine the abundance and size distribution of zooplankton was tested in Storfjorden, Norway, in June 1993. Selected material obtained from net sampling was measured with a laboratory version of the OPC and compared with microscope analysis...

  10. Effects of Photoactivated Titanium Dioxide Nanopowders and Coating on Planktonic and Biofilm Growth of Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Polo, Andrea; Diamanti, Maria Vittoria; Bjarnsholt, Thomas

    2011-01-01

    eradication of P. aeruginosa planktonic cells (initial concentration 10(8) cells/ml) in 24 h compared to a 3-log reduction caused by UV-A light alone. In contrast, neither the photocatalytic treatment with TiO(2) film nor that with TiO(2) nanopowder had any effect on P. aeruginosa biofilms at all...

  11. Inorganic mercury (Hg2+ uptake by different plankton fractions of Andean Patagonian lakes (Argentina

    Directory of Open Access Journals (Sweden)

    Diéguez M.C.

    2014-07-01

    Full Text Available The species composition and the size structure of natural planktonic food webs may provide essential information to understand the fate of mercury and, in particular, the bioaccumulation pattern of Hg2+ in the water column of lake ecosystems. Heterotrophic and autotrophic picoplankton and phytoplankton are the most important entry points for Hg in aquatic ecosystems since they concentrate Hg2+ and MeHg from ambient water, making them available to planktonic consumers at higher trophic levels of lake food webs. In this investigation we studied the uptake of 197Hg2+ in natural plankton assemblages from four Andean lakes (Nahuel Huapi National Park, Patagonia, Argentina, comprised in the size fractions 0.2-2.7 μm (picoplankton, 0.2-20 μm (pico and nanoplankton and 20-50 μm (microplankton through experiments using Hg2+ labeled with 197Hg2+. The experimental results showed that the uptake of Hg2+ was highest in the smallest plankton fractions (0.2-2.7 μm and 0.2-20 μm compared to the larger fraction comprising microplankton (20-50 um. This pattern was consistent in all lakes, reinforcing the idea that among pelagic organisms, heterotrophic and autotrophic bacteria with the contribution of nanoflagellates and dinoflagellates constitute the main entry point of Hg2+ to the pelagic food web. Moreover, a significant direct relationship was found between the Hg2+ uptake and surface index of the planktonic fractions (SIf. Thus, the smaller planktonic fractions which bore the higher SI were the major contributors to the Hg2+ passing from the abiotic to the biotic pelagic compartments of these Andean lakes.

  12. Non-destructive alpha-particle activation analysis of P, Cl, K and Ca in marine macro-alga samples using synthetic multielement reference material as comparative standard

    International Nuclear Information System (INIS)

    Iwata, Y.; Naitoh, H.; Suzuki, N.

    1992-01-01

    A Synthetic Reference Material (SyRM) composed with accurately known amounts of 12 elements has been prepared. The elemental composition of the SyRM is closely similar to that of marine macro-algae sample. The elemental composition of the SyRM was regulated by the starting materials used for the synthesis. The SyRM was used as a comparative standard for non-destructive alpha-particle activation analysis of marine macro-alga samples. P, Cl, K and Ca were determined simultaneously without correction for alpha range due to difference in the elemental composition between the analytical samples and the comparative standard. (author) 19 refs.; 4 tabs

  13. Community barcoding reveals little effect of ocean acidification on the composition of coastal plankton communities: Evidence from a long-term mesocosm study in the Gullmar Fjord, Skagerrak.

    Directory of Open Access Journals (Sweden)

    Julia A F Langer

    Full Text Available The acidification of the oceans could potentially alter marine plankton communities with consequences for ecosystem functioning. While several studies have investigated effects of ocean acidification on communities using traditional methods, few have used genetic analyses. Here, we use community barcoding to assess the impact of ocean acidification on the composition of a coastal plankton community in a large scale, in situ, long-term mesocosm experiment. High-throughput sequencing resulted in the identification of a wide range of planktonic taxa (Alveolata, Cryptophyta, Haptophyceae, Fungi, Metazoa, Hydrozoa, Rhizaria, Straminipila, Chlorophyta. Analyses based on predicted operational taxonomical units as well as taxonomical compositions revealed no differences between communities in high CO2 mesocosms (~ 760 μatm and those exposed to present-day CO2 conditions. Observed shifts in the planktonic community composition were mainly related to seasonal changes in temperature and nutrients. Furthermore, based on our investigations, the elevated CO2 did not affect the intraspecific diversity of the most common mesozooplankter, the calanoid copepod Pseudocalanus acuspes. Nevertheless, accompanying studies found temporary effects attributed to a raise in CO2. Differences in taxa composition between the CO2 treatments could, however, only be observed in a specific period of the experiment. Based on our genetic investigations, no compositional long-term shifts of the plankton communities exposed to elevated CO2 conditions were observed. Thus, we conclude that the compositions of planktonic communities, especially those in coastal areas, remain rather unaffected by increased CO2.

  14. Community barcoding reveals little effect of ocean acidification on the composition of coastal plankton communities: Evidence from a long-term mesocosm study in the Gullmar Fjord, Skagerrak.

    Science.gov (United States)

    Langer, Julia A F; Sharma, Rahul; Schmidt, Susanne I; Bahrdt, Sebastian; Horn, Henriette G; Algueró-Muñiz, María; Nam, Bora; Achterberg, Eric P; Riebesell, Ulf; Boersma, Maarten; Thines, Marco; Schwenk, Klaus

    2017-01-01

    The acidification of the oceans could potentially alter marine plankton communities with consequences for ecosystem functioning. While several studies have investigated effects of ocean acidification on communities using traditional methods, few have used genetic analyses. Here, we use community barcoding to assess the impact of ocean acidification on the composition of a coastal plankton community in a large scale, in situ, long-term mesocosm experiment. High-throughput sequencing resulted in the identification of a wide range of planktonic taxa (Alveolata, Cryptophyta, Haptophyceae, Fungi, Metazoa, Hydrozoa, Rhizaria, Straminipila, Chlorophyta). Analyses based on predicted operational taxonomical units as well as taxonomical compositions revealed no differences between communities in high CO2 mesocosms (~ 760 μatm) and those exposed to present-day CO2 conditions. Observed shifts in the planktonic community composition were mainly related to seasonal changes in temperature and nutrients. Furthermore, based on our investigations, the elevated CO2 did not affect the intraspecific diversity of the most common mesozooplankter, the calanoid copepod Pseudocalanus acuspes. Nevertheless, accompanying studies found temporary effects attributed to a raise in CO2. Differences in taxa composition between the CO2 treatments could, however, only be observed in a specific period of the experiment. Based on our genetic investigations, no compositional long-term shifts of the plankton communities exposed to elevated CO2 conditions were observed. Thus, we conclude that the compositions of planktonic communities, especially those in coastal areas, remain rather unaffected by increased CO2.

  15. The ecology of plankton in biological oceanography: a tribute to Marta Estrada’s task

    Directory of Open Access Journals (Sweden)

    Jordi Solé

    2016-09-01

    Full Text Available Plankton ecology has been the object of intense research and progress in the last few decades. This has been partly due to technological advances that have facilitated the multidisciplinary and high-resolution sampling of ecosystems and improved experimentation and analytical methodologies, and to sophisticated modelling. In addition, exceptional researchers have had the vision to integrate all these innovative tools to form a solid theoretical background in ecology. Here we provide an overview of the outstanding research work conducted by Professor Marta Estrada and her pioneering contribution to different areas of research in the last four decades. Her research in biological oceanography has mainly focussed on phytoplankton ecology, taxonomy and physiology, the functional structure of plankton communities, and physical and biological interactions in marine ecosystems. She has combined a variety of field and laboratory approaches and methodologies, from microscopy to satellite observations, including in-depth statistical data analysis and modelling. She has been a reference for scientists all over the world. Here, her contributions to plankton ecology are summarized by some of her students and closest collaborators, who had the privilege to share their science and everyday experiences with her.

  16. Mercury speciation in plankton from the Cabo Frio Bay, SE--Brazil.

    Science.gov (United States)

    Silva-Filho, Emmanoel V; Kütter, Vinicius T; Figueiredo, Thiago S; Tessier, Emmanuel; Rezende, Carlos E; Teixeira, Daniel C; Silva, Carlos A; Donard, Olivier F X

    2014-12-01

    Mercury (Hg) is considered a global pollutant, and the scientific community has shown great concern about its toxicity as it may affect the biota of entire systems, through bioaccumulation and bioamplification processes of its organic form, methylmercury (MeHg), along food web. However, few research studies deal with bioaccumulation of Hg from marine primary producers and the first-order consumers. So, this study aims to determine Hg distribution and concentration levels in phytoplankton and zooplankton in the Cabo Frio Bay, Brazil, a site influenced by coastal upwelling. The results from Hg speciation analyses show that inorganic mercury Hg(II) was the predominant specie in plankton from this bay. The annual Hg species distribution in plankton shown mean concentration of 2.00 ± 1.28 ng Hg(II) g(-1) and 0.15 ± 0.08 ng MeHg g(-1) wet weight (phytoplankton) and 2.5 ± 2.03 ng Hg(II) g(-1) and 0.25 ± 0.09 ng MeHg g(-1) wet weight (zooplankton). Therefore, upwelling zones should be considered in the Hg biogeochemical cycle models as a process that enhances Hg(II) bioaccumulation in plankton, raising its bioavailability and shelf deposition.

  17. Urban and marine corrosion: Comparative behaviour between field and laboratory conditions

    Energy Technology Data Exchange (ETDEWEB)

    Iribarren Laco, J.I.; Liesa Mestres, F.; Bilurbina Alter, L. [Departament d' Enginyeria Quimica E.T.S.E.I.B. Universitat Politecnica de Catalunya, Barcelona (Spain); Cadena Villota, F. [Departamento de Materiales, Escuela Politecnica Nacional, Quito (Ecuador)

    2004-09-01

    A detailed study of the corrosion phenomena of carbon steel has been investigated in this work by means of the comparison of field and laboratory tests. Two areas of the metropolitan area of Barcelona (Spain) were selected to carry out the field tests, whereas two different solutions of sodium chloride and sodium hydrogen sulfite were used to simulate the field conditions by means of cyclic laboratory tests. The corrosion rate has been evaluated from the weight loss of the specimens and the morphology surface has been visualized by optical and scanning electron microscopy. Corrosion products and contaminants have been analyzed by X-ray diffraction and energy-dispersive X-ray spectroscopy, respectively. The penetration results can be adjusted to the Passano equation and the corrosivity degree can be assigned in accordance with ISO standards. A correlation between field and laboratory tests has been found, by comparing the specimens with the same degree of corrosion, showing the validity of the accelerated laboratory tests in order to simulate the field conditions. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  18. Comparative Proteomic Analysis Reveals Proteins Putatively Involved in Toxin Biosynthesis in the Marine Dinoflagellate Alexandrium catenella

    Directory of Open Access Journals (Sweden)

    Da-Zhi Wang

    2013-01-01

    Full Text Available Alexandrium is a neurotoxin-producing dinoflagellate genus resulting in paralytic shellfish poisonings around the world. However, little is known about the toxin biosynthesis mechanism in Alexandrium. This study compared protein profiles of A. catenella collected at different toxin biosynthesis stages (non-toxin synthesis, initial toxin synthesis and toxin synthesizing coupled with the cell cycle, and identified differentially expressed proteins using 2-DE and MALDI-TOF-TOF mass spectrometry. The results showed that toxin biosynthesis of A. catenella occurred within a defined time frame in the G1 phase of the cell cycle. Proteomic analysis indicated that 102 protein spots altered significantly in abundance (P < 0.05, and 53 proteins were identified using database searching. These proteins were involved in a variety of biological processes, i.e., protein modification and biosynthesis, metabolism, cell division, oxidative stress, transport, signal transduction, and translation. Among them, nine proteins with known functions in paralytic shellfish toxin-producing cyanobacteria, i.e., methionine S-adenosyltransferase, chloroplast ferredoxin-NADP+ reductase, S-adenosylhomocysteinase, adenosylhomocysteinase, ornithine carbamoyltransferase, inorganic pyrophosphatase, sulfotransferase (similar to, alcohol dehydrogenase and arginine deiminase, varied significantly at different toxin biosynthesis stages and formed an interaction network, indicating that they might be involved in toxin biosynthesis in A. catenella. This study is the first step in the dissection of the behavior of the A. catenella proteome during different toxin biosynthesis stages and provides new insights into toxin biosynthesis in dinoflagellates.

  19. Comparative proteomic analysis reveals proteins putatively involved in toxin biosynthesis in the marine dinoflagellate Alexandrium catenella.

    Science.gov (United States)

    Wang, Da-Zhi; Gao, Yue; Lin, Lin; Hong, Hua-Sheng

    2013-01-22

    Alexandrium is a neurotoxin-producing dinoflagellate genus resulting in paralytic shellfish poisonings around the world. However, little is known about the toxin biosynthesis mechanism in Alexandrium. This study compared protein profiles of A. catenella collected at different toxin biosynthesis stages (non-toxin synthesis, initial toxin synthesis and toxin synthesizing) coupled with the cell cycle, and identified differentially expressed proteins using 2-DE and MALDI-TOF-TOF mass spectrometry. The results showed that toxin biosynthesis of A. catenella occurred within a defined time frame in the G1 phase of the cell cycle. Proteomic analysis indicated that 102 protein spots altered significantly in abundance (P translation. Among them, nine proteins with known functions in paralytic shellfish toxin-producing cyanobacteria, i.e., methionine S-adenosyltransferase, chloroplast ferredoxin-NADP+ reductase, S-adenosylhomocysteinase, adenosylhomocysteinase, ornithine carbamoyltransferase, inorganic pyrophosphatase, sulfotransferase (similar to), alcohol dehydrogenase and arginine deiminase, varied significantly at different toxin biosynthesis stages and formed an interaction network, indicating that they might be involved in toxin biosynthesis in A. catenella. This study is the first step in the dissection of the behavior of the A. catenella proteome during different toxin biosynthesis stages and provides new insights into toxin biosynthesis in dinoflagellates.

  20. The Continuous Plankton Imaging and Classification Sensor (CPICS): A Sensor for Quantifying Mesoplankton Biodiversity and Community Structure

    Science.gov (United States)

    Gallager, S. M.

    2016-02-01

    Marine ecosystems are changing at a variety of time scales as a function of a diverse suite of forcing functions both natural and anthropogenic. Establishing a continuous plankton time series consisting of scales from rapid (seconds) to long-term (decades), provides a sentinel for ecosystem change. The key is to measure plankton biodiversity at sufficiently fast time scales that allow disentanglement of physical (transport) and biological (growth) properties of an ecosystem. CPICS is a plankton and particle imaging microscope system that is designed to produce crisp darkfield images of light scattering material in aquatic environments. The open flow design is non-invasive and non-restrictive providing images of very fragile plankton in their natural orientation. Several magnifications are possible from 0.5 to 5x forming a field of view of 10cm to 1mm, respectively. CPICS has been installed on several cabled observing systems called OceanCubes off the coast of Okinawa and Tokyo, Japan providing a continuous stream of plankton images to a machine vision image classifier located at WHOI. Image features include custom algorithms for texture, color pattern, morphology and shape, which are extracted from in-focus target. The features are then used to train a classifier (e.g., Random Forest) resulting in classifications that are tested using cross-validation, confusion matrices and ROC curves. High (>90%) classification accuracies are possible depending on the number of training categories and target complexity. A web-based utility allows access to raw images, training sets, classifiers and classification results. Combined with chemical and physical data from the observatories, an ecologically meaningful plankton index of biodiversity and its variance is developed using a combination of species and taxon groups, which provides an approach for understanding ecosystem change without the need to identify all targets to species. http://oceancubes.whoi.edu/instruments/CPICS

  1. Comparative responses of two species of marine phytoplankton to metolachlor exposure

    International Nuclear Information System (INIS)

    Thakkar, Megha; Randhawa, Varunpreet; Wei Liping

    2013-01-01

    Metolachlor, a chloroacetanilide herbicide, has been frequently detected in coastal waters. This study examined the growth, photosynthesis, and detoxification responses of chlorophyte Dunaliella tertiolecta (DT) and brown tide alga Aureococcus anophagefferens (AA) upon 5-day exposure to 0.5–5 mg L −1 metolachlor. Growth was assessed with exponential growth rate, and 5th day in vivo chlorophyll fluorescence, chlorophyll a, b or c, cell density and cell size. The photosynthesis function was assessed with photochemical parameters of photosystem II (PSII) during the mid-exponential growth phase (i.e. 2–4 day metolachlor exposure). The biochemical detoxification was analyzed with glutathione production and metolachlor degradation. Results show that metolachlor caused up to ∼9% inhibition in growth rate in both species and an expected ∼35% and 25% inhibition in chlorophyll based endpoints in DT and AA respectively. DT had an up to 70% inhibition in cell density, but AA a 35% hormesis at 1 mg L −1 metolachlor and no significant inhibition, as compared to the controls. Both DT and AA's cell sizes were enlarged by metolachlor exposure, but greater in DT (1.2% per mg L −1 ) than in AA (0.68% per mg L −1 ). On PSII photochemistry, maximum quantum yield was not affected in both species; PSII optical cross section and connectivity factor increased in DT but decreased in AA, suggesting species specific impact on PSII function. On detoxification responses, glutathione production, when normalized to total chlorophyll a, was not affected by metolachlor in both species; further, despite of heterotrophic capacity of A. anophagefferens metolachlor was not significantly degraded by this alga during the 5-day incubation. The species specific effects on algal growth have ecological implications of potential selective inhibition of chlorophytes by metolachlor herbicide.

  2. Biofilms and planktonic cells of Deinococcus geothermalis in extreme environments

    Science.gov (United States)

    Panitz, Corinna; Reitz, Guenther; Rabbow, Elke; Rettberg, Petra; Flemming, Hans-Curt; Wingender, Jost; Froesler, Jan

    In addition to the several extreme environments on Earth, Space can be considered as just another exceptional environment with a unique mixture of stress factors comprising UV radiation, vacuum, desiccation, temperature, ionizing radiation and microgravity. Life that processes in these environments can depend on the life forms and their state of living. The question is whether there are different strategies for individual microorganisms compared to communities of the same organisms to cope with the different factors of their surroundings. Comparative studies of the survi-val of these communities called biofilms and planktonic cell samples of Deinococcus geothermalis stand at the focal point of the presented investigations. A biofilm is a structured community of microorganisms that live encapsulated in a matrix of extracellular polymeric substances on a surface. Microorganisms living in a biofilm usually have significantly different properties to cooperate than individually living microorganisms of the same species. An advantage of the biofilm is increased resistance to various chemical and physical effects, while the dense extracellular matrix and the outer layer of the cells protect the interior of the microbial consortium. The space experiment BOSS (Biofilm organisms surfing Space) as part the ESA experimental unit EXPOSE R-2 with a planned launch date in July 2014 will be subsequently mounted on the Russian Svesda module outside the ISS. An international team of scientists coordinated by Dr. P. Rettberg will investigate the hypothesis whether microorganisms organized as biofilm outmatch the same microorganisms exposed individually in the long-term survival of the harsh environmental conditions as they occur in space and on Mars. Another protective function in the samples could be dust par-ticles for instance Mars regolith simulant contained inside the biofilms or mixed with the planktonic cells, as additional shelter especially against the extraterrestrial UV

  3. Impact of ultraviolet-B radiation on planktonic fish larvae: Alteration of the osmoregulatory function

    Energy Technology Data Exchange (ETDEWEB)

    Sucre, Elliott, E-mail: elliott.sucre@univ-montp2.fr [AEO Team (Adaptation Ecophysiologique et Ontogenese), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc092, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Vidussi, Francesca [RESEAUX Team (Reseaux Planctoniques et Changement Environnemental), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc093, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Mostajir, Behzad [RESEAUX Team (Reseaux Planctoniques et Changement Environnemental), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc093, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Centre d' ecologie marine experimentale MEDIMEER (Mediterranean centre for Marine Ecosystem Experimental Research), Universite Montpellier 2-CNRS (UMS 3301), Station Mediterraneenne de l' Environnement Littoral, MEDIMEER, 2 Rue des Chantiers, 34200 Sete (France); Charmantier, Guy; Lorin-Nebel, Catherine [AEO Team (Adaptation Ecophysiologique et Ontogenese), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc092, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France)

    2012-03-15

    Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 {mu}W cm{sup -2}: 4 h L/20 h D) and medium (80 {mu}W cm{sup -2}: 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na{sup +}/K{sup +}-ATPase and the Na{sup +}/K{sup +}/2Cl{sup -} cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.

  4. COPEPOD: The Coastal & Oceanic Plankton Ecology, Production, & Observation Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coastal & Oceanic Plankton Ecology, Production, & Observation Database (COPEPOD) provides NMFS scientists with quality-controlled, globally distributed...

  5. Modeling physiological processes in plankton on enzyme kinetic principles

    Directory of Open Access Journals (Sweden)

    Ted Packard

    2004-04-01

    Full Text Available Many ecologically important chemical transformations in the ocean are controlled by biochemical enzyme reactions in plankton. Nitrogenase regulates the transformation of N2 to ammonium in some cyanobacteria and serves as the entryway for N2 into the ocean biosphere. Nitrate reductase controls the reduction of NO3 to NO2 and hence new production in phytoplankton. The respiratory electron transfer system in all organisms links the carbon oxidation reactions of intermediary metabolism with the reduction of oxygen in respiration. Rubisco controls the fixation of CO2 into organic matter in phytoplankton and thus is the major entry point of carbon into the oceanic biosphere. In addition to these, there are the enzymes that control CO2 production, NH4 excretion and the fluxes of phosphate. Some of these enzymes have been recognized and researched by marine scientists in the last thirty years. However, until recently the kinetic principles of enzyme control have not been exploited to formulate accurate mathematical equations of the controlling physiological expressions. Were such expressions available they would increase our power to predict the rates of chemical transformations in the extracellular environment of microbial populations whether this extracellular environment is culture media or the ocean. Here we formulate from the principles of bisubstrate enzyme kinetics, mathematical expressions for the processes of NO3 reduction, O2 consumption, N2 fixation, total nitrogen uptake.

  6. Contribution of offshore petroleum deposits to marine food chain

    Science.gov (United States)

    Mori, S.

    2009-12-01

    Petroleum production out of offshore petroleum deposits often coincides with abundant fisheries in the world. Superposition of marine microorganism concentration distribution and offshore petroleum field distribution from various data in the literature provides to prove this coincidence. Sakhalin Island coastal regions, North Sea, Gulf of Mexico, etc. are chosen for the superpositions. Significant conformity is observed between the plankton concentration distribution and the offshore petroleum deposit distribution in all those regions. Also, most studies on the consequence of oil spills to marine eco-systems have focused mainly on hazardous marine pollution caused by spilled petroleum at high concentration in marine environment. However, some of those data clearly indicate stimulation of plankton population in properly low concentration levels of dissolved hydrocarbons and dissolved petroleum compositions. Further, increase of hydrocarbon concentration leads to its inhibition from its stimulation conditions upon crossing over a critical concentration level—a plankton stimulation/inhibition threshold concentration (SITC) of hydrocarbons. The SITC varies depending on hydrocarbon compounds, petroleum compositions, and microorganisms such as planktons. Further, petroleum composition diffusing through subterranean layers from petroleum deposits reacts with dissolved oxygen to be consumed at the ocean floor to precipitate the agglomerate suspension of hydrocarbons, leaving the sea water in a condition of oxygen depletion on the ocean floor. Such incidents are also briefly discussed.Plankton stimulation/inhibition threshold concentration of petroleum fractions

  7. Planktonic Foraminifera Proxies Calibration Off the NW Iberian Margin: Nutrients Approach

    Science.gov (United States)

    Salgueiro, E.; Castro, C. G.; Zuniga, D.; Martin, P. A.; Groeneveld, J.; de la Granda, F.; Villaceiros-Robineau, N.; Alonso-Perez, F.; Alberto, A.; Rodrigues, T.; Rufino, M. M.; Abrantes, F. F. G.; Voelker, A. H. L.

    2014-12-01

    Planktonic foraminifera (PF) shells preserved in marine sediments are a useful tool to reconstruct productivity conditions at different geological timescales. However, the accuracy of these paleoreconstructions depends on the data set and calibration quality. Several calibration works have been defining and improving the use of proxies for productivity and nutrient cycling parameters. Our contribution is centred on a multi-proxy calibration at a regional coastal upwelling system. To minimize the existing uncertainties affecting the use of trace elements and C stable isotopes as productivity proxy in the high productivity upwelling areas, we investigate the content and distribution of Ba/Ca and δ13C in the water column, its transference into the planktonic foraminifera shells, and, how the living planktonic foraminifera Ba/Ca and δ13C signal is related to the same planktonic foraminiferal species preserved in the sediment record. This study is based on a large data set from two stations (RAIA - 75m water depth, and CALIBERIA - 350m water depth) located off the NW Iberian margin (41.5-42.5ºN; 9-10ºW), and includes: i) two year monthly water column data (temperature, salinity, nutrients, chlorophyll a, Ba/Ca, and δ13C-DIC); ii) seasonal Ba/Ca, δ13C in several living PF species at both stations; and iii) Ba/Ca and δ13C in several PF species from a large set of core-top sediment samples in the study region. Additionally, total organic carbon and total alkenones were also measured in the sediment. Our results showed the link between productivity proxies in the surface sediment foraminifera assemblage and the processes regulating the actual phytoplankton dynamics in an upwelling area. The understanding of this relationship has special relevance since it gives fundamental information related to the past oceanic biogeochemistry and/or climate and improves the prevision of future changes against possible climate variability due to anthropogenic forcing.

  8. Comparative evaluation of analytical procedures for the recovery of Enterobacteriaceae in coastal marine waters; Valutazione comparativa di procedure analitiche per il rilevamento di Enterobacteriaceae in acque marine costiere

    Energy Technology Data Exchange (ETDEWEB)

    Bonadonna, Lucia; Chiaretti, Gianluca; Coccia, Anna Maria; Semproni, Maurizio [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Igiene Ambientale

    1997-03-01

    The use of quick and reliable procedures is fundamental for water quality evaluation control. In order to improve the analytical methods for microbiological examination of bathing waters, a comparison of different substrates for the recovery of Enterobacteriaceae from coastal marine waters was carried out. The medium indicated in the Italian technical normative has shown a good selectivity when the red colonies with a green metallic surface sheen were counted, as stated in the Standard Methods. On the other hand, the chronogenic substrate used in this study resulted easy to read, selective and specific for both Escherichia coli and total coliforms.

  9. Designing connected marine reserves in the face of global warming.

    Science.gov (United States)

    Álvarez-Romero, Jorge G; Munguía-Vega, Adrián; Beger, Maria; Del Mar Mancha-Cisneros, Maria; Suárez-Castillo, Alvin N; Gurney, Georgina G; Pressey, Robert L; Gerber, Leah R; Morzaria-Luna, Hem Nalini; Reyes-Bonilla, Héctor; Adams, Vanessa M; Kolb, Melanie; Graham, Erin M; VanDerWal, Jeremy; Castillo-López, Alejandro; Hinojosa-Arango, Gustavo; Petatán-Ramírez, David; Moreno-Baez, Marcia; Godínez-Reyes, Carlos R; Torre, Jorge

    2018-02-01

    Marine reserves are widely used to protect species important for conservation and fisheries and to help maintain ecological processes that sustain their populations, including recruitment and dispersal. Achieving these goals requires well-connected networks of marine reserves that maximize larval connectivity, thus allowing exchanges between populations and recolonization after local disturbances. However, global warming can disrupt connectivity by shortening potential dispersal pathways through changes in larval physiology. These changes can compromise the performance of marine reserve networks, thus requiring adjusting their design to account for ocean warming. To date, empirical approaches to marine prioritization have not considered larval connectivity as affected by global warming. Here, we develop a framework for designing marine reserve networks that integrates graph theory and changes in larval connectivity due to potential reductions in planktonic larval duration (PLD) associated with ocean warming, given current socioeconomic constraints. Using the Gulf of California as case study, we assess the benefits and costs of adjusting networks to account for connectivity, with and without ocean warming. We compare reserve networks designed to achieve representation of species and ecosystems with networks designed to also maximize connectivity under current and future ocean-warming scenarios. Our results indicate that current larval connectivity could be reduced significantly under ocean warming because of shortened PLDs. Given the potential changes in connectivity, we show that our graph-theoretical approach based on centrality (eigenvector and distance-weighted fragmentation) of habitat patches can help design better-connected marine reserve networks for the future with equivalent costs. We found that maintaining dispersal connectivity incidentally through representation-only reserve design is unlikely, particularly in regions with strong asymmetric patterns of

  10. A Comparative biochemical study on two marine endophytes, Bacterium SRCnm and Bacillus sp. JS, Isolated from red sea algae.

    Science.gov (United States)

    Ahmed, Eman Fadl; Hassan, Hossam Mokhtar; Rateb, Mostafa Ezzat; Abdel-Wahab, Noha; Sameer, Somayah; Aly Taie, Hanan Anwar; Abdel-Hameed, Mohammed Sayed; Hammouda, Ola

    2016-01-01

    Two marine endophytic bacteria were isolated from the Red Sea algae; a red alga; Acanthophora dendroides and the brown alga Sargassum sabrepandum. The isolates were identified based on their 16SrRNA sequences as Bacterium SRCnm and Bacillus sp. JS. The objective of this study was to investigate the potential anti-microbial and antioxidant activities of the extracts of the isolated bacteria grown in different nutrient conditions. Compared to amoxicillin (25μg/disk) and erythromycin (15μg/disk), the extracts of Bacterium SRCn min media II, III, IV and V were potent inhibitors of the gram-positive bacterium Sarcina maxima even at low concentrations. Also, the multidrug resistant Staphylococcus aureus(MRSA) was more sensitive to the metabolites produced in medium (II) of the same endophyte than erythromycin (15μg/disk). A moderate activity of the Bacillus sp. JS extracts of media I and II was obtained against the same pathogen. The total compounds (500ug/ml) of both isolated endophytes showed moderate antioxidant activities (48.9% and 46.1%, respectively). LC/MS analysis of the bacterial extracts was carried out to investigate the likely natural products produced. Cyclo(D-cis-Hyp-L-Leu), dihydrosphingosine and 2-Amino-1,3-hexadecanediol were identified in the fermentation medium of Bacterium SRCnm, whereas cyclo (D-Pro-L-Tyr) and cyclo (L-Leu-L-Pro) were the suggested compounds of Bacillus sp. JS.

  11. Intraseasonal patterns in coastal plankton biomass off central Chile derived from satellite observations and a biochemical model

    Science.gov (United States)

    Gomez, Fabian A.; Spitz, Yvette H.; Batchelder, Harold P.; Correa-Ramirez, Marco A.

    2017-10-01

    Subseasonal (5-130 days) environmental variability can strongly affect plankton dynamics, but is often overlooked in marine ecology studies. We documented the main subseasonal patterns of plankton biomass in the coastal upwelling system off central Chile, the southern part of the Humboldt System. Subseasonal variability was extracted from temporal patterns in satellite data of wind stress, sea surface temperature, and chlorophyll from the period 2003-2011, and from a realistically forced eddy-resolving physical-biochemical model from 2003 to 2008. Although most of the wind variability occurs at submonthly frequencies (< 30 days), we found that the dominant subseasonal pattern of phytoplankton biomass is within the intraseasonal band (30-90 days). The strongest intraseasonal coupling between wind and plankton is in spring-summer, when increased solar radiation enhances the phytoplankton response to upwelling. Biochemical model outputs show intraseasonal shifts in plankton community structure, mainly associated with the large fluctuations in diatom biomass. Diatom biomass peaks near surface during strong upwelling, whereas small phytoplankton biomass peaks at subsurface depths during relaxation or downwelling periods. Strong intraseasonally forced changes in biomass and species composition could strongly impact trophodynamics connections in the ecosystem, including the recruitment of commercially important fish species such as common sardine and anchovy. The wind-driven variability of chlorophyll concentration was connected to mid- and high-latitude atmospheric anomalies, which resemble disturbances with frequencies similar to the tropical Madden-Julian Oscillation.

  12. Influence of water mixing and food web status on the response of planktonic communities to enhanced ultraviolet-B radiation

    Science.gov (United States)

    Mostajir, B.; Uvbr Team

    2003-04-01

    Two series of mesocosm experiments were carried out in 1996 and 1997 using the natural planktonic assemblage, ultraviolet-B radiation (UVBR: 280-320 nm) at the community level. The water used in the first experiment was rich in nitrate (ca. 8-10 μM) and phytoplankton biomass (5 μg Chlorophyll a L-1: Chl a), conditions typical of an eutrophic coastal zone with herbivorous food web characteristics. In contrast, the water used in the second experiment was poor in nitrate (food web. Furthermore, to understand the influence of vertical mixing on the effects of UVBR on the planktonic community, two mixing regimes (fast and slow) were tested during the mesocosm experiments of 1997. The results showed that the mixing regime can moderate the effects of UVBR on the planktonic community and can also modify completely the species composition in the mesocosms much more than the UVBR. Comparison between the impact of UVBR on the planktonic community presented in these two experiments suggested that regenerated production-based systems (e.g. microbial food webs) tolerate the effects of UVBR more efficiently than do new production-based systems (herbivorous food webs). Results regarding the potential effects of UVBR in different marine systems, coastal versus oceanic, where different physical systems dominate, fast versus slow mixing, and consequently the development of different food webs are favored, herbivorous versus microbial, will be discussed.

  13. Toxicity of waters from the Rochester Embayment Area of Concern to the plankton species Pseudokirchneriella subcapitata and Ceriodaphnia dubia

    Science.gov (United States)

    Baldigo, Barry P.; Duffy, Brian T.; Smith, Alexander J.; George, Scott D.

    2016-01-01

    The lower Genesee River and Rochester Embayment of Lake Ontario are a designated Area of Concern (AOC) under the binational Great Lakes Water Quality Agreement. The “degradation of phytoplankton and zooplankton populations” or plankton Beneficial Use Impairment (BUI) was classified as unknown and in need of further assessment in this AOC because water quality data suggested plankton communities could be effected and community data were either unavailable or indicated impacts. The plankton BUI may now be obsolete because local contaminant sources have been largely eliminated. The present study was conducted between July 2013 and August 2014 to assess the BUI-removal criteria: “AOC plankton bioassays confirm that toxicity in ambient waters (i.e., no growth inhibition) is not significantly higher than comparable non-AOC controls”. Acute and chronic toxicity of waters from 13 sites were quantified seasonally using standardized bioassays with the green alga Pseudokirchneriella subcapitata and water flea Ceriodaphnia dubia to test the hypothesis that toxicity of waters from AOC sites was not higher than that of waters from comparable non-AOC reference sites. Survival and reproduction of C. dubia did not differ significantly between site types, systems, or months. The growth of P. subcapitata did not differ between site types, but differed among systems and months. All results indicate that waters from AOC sites were no more toxic to both plankton species than waters from reference sites. Assuming test species represent natural plankton assemblages, water quality should not negatively affect survival and growth of resident plankton populations in the Rochester Embayment AOC.

  14. Planktonic percentage of foraminiferal fauna in surface sediments of the Arabian sea (Indian Ocean) and a regional model for paleodepth determination

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Henriques, P.J.

    with previous studies in other areas that planktonic percentage increased with depth. The resultant pattern is compared with results from the Atlantic margin of the northeastern United States, Gulf of Mexico, Timor Sea and Red Sea. Comparisons reveal...

  15. Antimicrobial Resistance Profile of Planktonic and Biofilm Cells of Staphylococcus aureus and Coagulase-Negative Staphylococci

    Directory of Open Access Journals (Sweden)

    Adilson de Oliveira

    2016-09-01

    Full Text Available The objective of the present study was to determine the antimicrobial resistance profile of planktonic and biofilm cells of Staphylococcus aureus and coagulase-negative staphylococci (CoNS. Two hundred Staphylococcus spp. strains were studied, including 50 S. aureus and 150 CoNS strains (50 S. epidermidis, 20 S. haemolyticus, 20 S. warneri, 20 S. hominis, 20 S. lugdunensis, and 20 S. saprophyticus. Biofilm formation was investigated by adherence to polystyrene plates. Positive strains were submitted to the broth microdilution method to determine the minimum inhibitory concentration (MIC for planktonic and biofilm cells and the minimal bactericidal concentration for biofilm cells (MBCB. Forty-nine Staphylococcus spp. strains (14 S. aureus, 13 S. epidermidis, 13 S. saprophyticus, 3 S. haemolyticus, 1 S. hominis, 3 S. warneri, and 2 S. lugdunensis were biofilm producers. These isolates were evaluated regarding their resistance profile. Determination of planktonic cell MIC identified three (21.4% S. aureus strains that were resistant to oxacillin and six (42.8% that were resistant to erythromycin. Among the CoNS, 31 (88.6% strains were resistant to oxacillin, 14 (40% to erythromycin, 18 (51.4% to gentamicin, and 8 (22.8% to sulfamethoxazole/trimethoprim. None of the planktonic isolates were resistant to vancomycin or linezolid. MICs were 2-, 4-, 8-, and up to 16-fold higher for biofilm cells than for planktonic cells. This observation was more common for vancomycin and erythromycin. The MBCB ranged from 8 to >256 µg/mL for oxacillin, 128 to >128 µg/mL for vancomycin, 256 to >256 µg/mL for erythromycin and gentamicin, >64 µg/mL for linezolid, and 32/608 to >32/608 µg/mL for sulfamethoxazole/trimethoprim. The results showed considerably higher MICs for S. aureus and CoNS biofilm cells compared to planktonic cells. Analysis of MBCM confirmed that even high concentrations of vancomycin were unable to eliminate the biofilms of S. aureus and Co

  16. Zooplankton motile behavior: traits and trade-offs in planktonic copepods

    DEFF Research Database (Denmark)

    van Someren Gréve, Hans

    Research on planktonic copepod ecology is vital to understand the factors controlling marine food web dynamics since copepods are the major components of zooplankton communities and the main link between trophic levels in marine environments. Despite their taxonomic diversity, copepods share...... certain phenotypic characteristics, or ´traits´, that are essential in determining trophic interactions and fitness. One important characteristic that decisively influences organism interactions is behavior. Copepods display two distinct behavioral strategies in terms of motility: ´active´ (feeding...... differences between genders in feeding efficiency and predation risk. Finally, we also found that foraging activity decreased with increasing food availability, especially in active feeding strategies, resulting in a decrease in predation risk. Therefore, changes in behavior depending on food availability...

  17. Epithelial cell detachment by Porphyromonas gingivalis biofilm and planktonic cultures

    NARCIS (Netherlands)

    Huang, L.; van Loveren, C.; Ling, J.; Wei, X.; Crielaard, W.; Deng, D.M.

    2016-01-01

    Porphyromonas gingivalis is present as a biofilm at the sites of periodontal infections. The detachment of gingival epithelial cells induced by P. gingivalis biofilms was examined using planktonic cultures as a comparison. Exponentially grown planktonic cultures or 40-h biofilms were co-incubated

  18. Larval and Juvenile Ascothoracida (Crustacea) from the Plankton

    OpenAIRE

    Grygier, Mark J.

    1988-01-01

    Two kinds of previously recorded ascothoracid larvae from plankton over coral reefs in Hawaii and the Virgin Islands are redescribed as possible representatives of the Lauridae and Petrarcidae, respectively. A bathyal, tropical Atlantic ascothoracid larva from an epibenthic sled sample cannot confidently be identified to family. A planktonic, juvenile ascothoracidan from the eastern Indian Ocean belongs to the genus Synagoga.

  19. Key to marine arthropod larvae

    Directory of Open Access Journals (Sweden)

    John A. Fornshell

    2012-03-01

    Full Text Available The scope of this key is restricted to the larvae of marine arthropods. The key is based solely on their morphology, patterns of body segmentation, numbers of appendages, and mode of locomotion. An effort has been made to treat all traditionally named larval forms, both planktonic and benthic. It is intended that this key be useful for a researcher working with archived museum specimens and therefore, does not include habitat information as a identifying trait, even though this information is usually available in the archived records. Within the phylum Arthropoda there are two sub-phyla and eleven classes having larval stages in the marineenvironment. Where feasible the original names of the various larval types have been used. Because this nomenclature is less commonly used today compared to the past, the more recent taxonomic affinities are included in parentheses after the original larval name. The key includes the following thirty-four larvae: Branchhiopoda nauplii; Cephalocarida nauplii; Mystacocarida nauplii; trilobite larva; protonymphon; hexapod larvae; Remipedia nauplii; nauplius - Y larvae; Cirripedia nauplii; Ascothoracida nauplii; Ostracoda nauplii; Euphausiacea nauplii; Penaeidea nauplii; Cyclopoida nauplii; Calanoida nauplii; Harpacticoida nauplii;Polyarthra nauplii; cypris larva; eryonecius larva; cypris-Y larva; elapthocaris larvae; mysis larvae; lucifer zoea; acetes zoea; acanthosoma larva; phyllosoma; antizoea larva; anomuran zoea; brachyuran zoea; calyptopis larvae; furcilia larva; crytopia larva; puerulus larva; alima larva.

  20. Phylogeography of the tropical planktonic foraminifera lineage globigerinella reveals isolation inconsistent with passive dispersal by ocean currents.

    Directory of Open Access Journals (Sweden)

    Agnes K M Weiner

    Full Text Available Morphologically defined species of marine plankton often harbor a considerable level of cryptic diversity. Since many morphospecies show cosmopolitan distribution, an understanding of biogeographic and evolutionary processes at the level of genetic diversity requires global sampling. We use a database of 387 single-specimen sequences of the SSU rDNA of the planktonic foraminifera Globigerinella as a model to assess the biogeographic and phylogenetic distributions of cryptic diversity in marine microplankton on a global scale. Our data confirm the existence of multiple, well isolated genetic lineages. An analysis of their abundance and distribution indicates that our sampling is likely to approximate the actual total diversity. Unexpectedly, we observe an uneven allocation of cryptic diversity among the phylogenetic lineages. We show that this pattern is neither an artifact of sampling intensity nor a function of lineage age. Instead, we argue that it reflects an ongoing speciation process in one of the three major lineages. Surprisingly, four of the six genetic types in the hyperdiverse lineage are biogeographically restricted to the Indopacific. Their mutual co-occurrence and their hierarchical phylogenetic structure provide no evidence for an origin through sudden habitat fragmentation and their limitation to the Indopacific challenges the view of a global gene flow within the warm-water provinces. This phenomenon shows that passive dispersal is not sufficient to describe the distribution of plankton diversity. Rather, these organisms show differentiated distribution patterns shaped by species interactions and reflecting phylogenetic contingency with unique histories of diversification rates.

  1. Phylogeography of the tropical planktonic foraminifera lineage globigerinella reveals isolation inconsistent with passive dispersal by ocean currents.

    Science.gov (United States)

    Weiner, Agnes K M; Weinkauf, Manuel F G; Kurasawa, Atsushi; Darling, Kate F; Kucera, Michal; Grimm, Guido W

    2014-01-01

    Morphologically defined species of marine plankton often harbor a considerable level of cryptic diversity. Since many morphospecies show cosmopolitan distribution, an understanding of biogeographic and evolutionary processes at the level of genetic diversity requires global sampling. We use a database of 387 single-specimen sequences of the SSU rDNA of the planktonic foraminifera Globigerinella as a model to assess the biogeographic and phylogenetic distributions of cryptic diversity in marine microplankton on a global scale. Our data confirm the existence of multiple, well isolated genetic lineages. An analysis of their abundance and distribution indicates that our sampling is likely to approximate the actual total diversity. Unexpectedly, we observe an uneven allocation of cryptic diversity among the phylogenetic lineages. We show that this pattern is neither an artifact of sampling intensity nor a function of lineage age. Instead, we argue that it reflects an ongoing speciation process in one of the three major lineages. Surprisingly, four of the six genetic types in the hyperdiverse lineage are biogeographically restricted to the Indopacific. Their mutual co-occurrence and their hierarchical phylogenetic structure provide no evidence for an origin through sudden habitat fragmentation and their limitation to the Indopacific challenges the view of a global gene flow within the warm-water provinces. This phenomenon shows that passive dispersal is not sufficient to describe the distribution of plankton diversity. Rather, these organisms show differentiated distribution patterns shaped by species interactions and reflecting phylogenetic contingency with unique histories of diversification rates.

  2. Progress in Late Cretaceous planktonic foraminiferal stable isotope paleoecology and implications for paleoceanographic reconstructions

    Science.gov (United States)

    Petrizzo, Maria Rose; Falzoni, Francesca; Huber, Brian T.; MacLeod, Kenneth G.

    2015-04-01

    were adapted to shallow layers and eutrophic environments (Falzoni et al., 2013; Falzoni et al., in prep.). Interestingly, globigeriniform planktonic foraminifera with meridional ornamentation (Paracostellagerina and Rugoglobigerina), a morphological feature generally considered to be genetically controlled and thus taxonomically significant, typically yield higher δ13C values than co-occurring finely ornamented morphotypes (Petrizzo et al., 2008). A possible explanation to these results invokes the presence of facultative photosymbionts enhancing test calcification or alternatively, the occurrence of ecophenotypes adapted to a different sea-surface 13C/12C ratio within the same fossil species (Falzoni et al., 2014). Finally, we discuss evidences against the traditional species depth-distribution model and highlight the restrictions in performing Late Cretaceous paleoenvironmental and paleoceanographic reconstructions based on shell morphology and/or inferred life strategies of planktonic foraminifera. References Falzoni, F., Petrizzo, M.R., MacLeod, K.G., Huber, B.T. (2013). Santonian-Campanian planktonic foraminifera from Tanzania, Shatsky Rise and Exmouth Plateau: species depth ecology and paleoceanographic inferences. Marine Micropaleontology 103, 15-29. Falzoni, F., Petrizzo, M.R., Huber, B.T., MacLeod, K.G. (2014). Insights into the meridional ornamentation of the planktonic foraminiferal genus Rugoglobigerina (Late Cretaceous) and implications for taxonomy. Cretaceous Research 47, 87-104. Petrizzo, M.R., Huber, B.T., Wilson, P.A., MacLeod, K.G. (2008). Late Albian paleoceanography of the western subtropical North Atlantic. Paleoceanography 23. http://dx.doi.org/10.1029/2007PA001517 (PA1213).

  3. Xylella fastidiosa differentially accumulates mineral elements in biofilm and planktonic cells.

    Science.gov (United States)

    Cobine, Paul A; Cruz, Luisa F; Navarrete, Fernando; Duncan, Daniel; Tygart, Melissa; De La Fuente, Leonardo

    2013-01-01

    Xylella fastidiosa is a bacterial plant pathogen that infects numerous plant hosts. Disease develops when the bacterium colonizes the xylem vessels and forms a biofilm. Inductively coupled plasma optical emission spectroscopy was used to examine the mineral element content of this pathogen in biofilm and planktonic states. Significant accumulations of copper (30-fold), manganese (6-fold), zinc (5-fold), calcium (2-fold) and potassium (2-fold) in the biofilm compared to planktonic cells were observed. Other mineral elements such as sodium, magnesium and iron did not significantly differ between biofilm and planktonic cells. The distribution of mineral elements in the planktonic cells loosely mirrors the media composition; however the unique mineral element distribution in biofilm suggests specific mechanisms of accumulation from the media. A cell-to-surface attachment assay shows that addition of 50 to 100 µM Cu to standard X. fastidiosa media increases biofilm, while higher concentrations (>200 µM) slow cell growth and prevent biofilm formation. Moreover cell-to-surface attachment was blocked by specific chelation of copper. Growth of X. fastidiosa in microfluidic chambers under flow conditions showed that addition of 50 µM Cu to the media accelerated attachment and aggregation, while 400 µM prevented this process. Supplementation of standard media with Mn showed increased biofilm formation and cell-to-cell attachment. In contrast, while the biofilm accumulated Zn, supplementation to the media with this element caused inhibited growth of planktonic cells and impaired biofilm formation. Collectively these data suggest roles for these minerals in attachment and biofilm formation and therefore the virulence of this pathogen.

  4. Xylella fastidiosa differentially accumulates mineral elements in biofilm and planktonic cells.

    Directory of Open Access Journals (Sweden)

    Paul A Cobine

    Full Text Available Xylella fastidiosa is a bacterial plant pathogen that infects numerous plant hosts. Disease develops when the bacterium colonizes the xylem vessels and forms a biofilm. Inductively coupled plasma optical emission spectroscopy was used to examine the mineral element content of this pathogen in biofilm and planktonic states. Significant accumulations of copper (30-fold, manganese (6-fold, zinc (5-fold, calcium (2-fold and potassium (2-fold in the biofilm compared to planktonic cells were observed. Other mineral elements such as sodium, magnesium and iron did not significantly differ between biofilm and planktonic cells. The distribution of mineral elements in the planktonic cells loosely mirrors the media composition; however the unique mineral element distribution in biofilm suggests specific mechanisms of accumulation from the media. A cell-to-surface attachment assay shows that addition of 50 to 100 µM Cu to standard X. fastidiosa media increases biofilm, while higher concentrations (>200 µM slow cell growth and prevent biofilm formation. Moreover cell-to-surface attachment was blocked by specific chelation of copper. Growth of X. fastidiosa in microfluidic chambers under flow conditions showed that addition of 50 µM Cu to the media accelerated attachment and aggregation, while 400 µM prevented this process. Supplementation of standard media with Mn showed increased biofilm formation and cell-to-cell attachment. In contrast, while the biofilm accumulated Zn, supplementation to the media with this element caused inhibited growth of planktonic cells and impaired biofilm formation. Collectively these data suggest roles for these minerals in attachment and biofilm formation and therefore the virulence of this pathogen.

  5. Examination of a high resolution laser optical plankton counter and FlowCAM for measuring plankton concentration and size

    Science.gov (United States)

    Kydd, Jocelyn; Rajakaruna, Harshana; Briski, Elizabeta; Bailey, Sarah

    2018-03-01

    Many commercial ships will soon begin to use treatment systems to manage their ballast water and reduce the global transfer of harmful aquatic organisms and pathogens in accordance with upcoming International Maritime Organization regulations. As a result, rapid and accurate automated methods will be needed to monitoring compliance of ships' ballast water. We examined two automated particle counters for monitoring organisms ≥ 50 μm in minimum dimension: a High Resolution Laser Optical Plankton Counter (HR-LOPC), and a Flow Cytometer with digital imaging Microscope (FlowCAM), in comparison to traditional (manual) microscopy considering plankton concentration, size frequency distributions and particle size measurements. The automated tools tended to underestimate particle concentration compared to standard microscopy, but gave similar results in terms of relative abundance of individual taxa. For most taxa, particle size measurements generated by FlowCAM ABD (Area Based Diameter) were more similar to microscope measurements than were those by FlowCAM ESD (Equivalent Spherical Diameter), though there was a mismatch in size estimates for some organisms between the FlowCAM ABD and microscope due to orientation and complex morphology. When a single problematic taxon is very abundant, the resulting size frequency distribution curves can become skewed, as was observed with Asterionella in this study. In particular, special consideration is needed when utilizing automated tools to analyse samples containing colonial species. Re-analysis of the size frequency distributions with the removal of Asterionella from FlowCAM and microscope data resulted in more similar curves across methods with FlowCAM ABD having the best fit compared to the microscope, although microscope concentration estimates were still significantly higher than estimates from the other methods. The results of our study indicate that both automated tools can generate frequency distributions of particles

  6. Comparative safety of the antifouling compound butenolide and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) to the marine medaka (Oryzias melastigma)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lianguo [Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region (Hong Kong); Ye, Rui [State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Xu, Ying; Gao, Zhaoming [Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region (Hong Kong); Au, Doris W.T. [State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Qian, Pei-Yuan, E-mail: boqianpy@ust.hk [Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region (Hong Kong)

    2014-04-01

    Highlights: • Adverse effects of antifouling compound butenolide were studied using marine medaka. • The active ingredient in SeaNine 211, DCOIT, was employed as positive control. • Butenolide induced transient, reversible biological effects on marine medaka. • Lower toxicity of butenolide on marine biota highlights its promising application. • The increased sensitivity of male medaka addresses the gender difference. - Abstract: This study evaluated the potential adverse effects of butenolide, a promising antifouling compound, using the marine medaka (Oryzias melastigma), a model fish for marine ecotoxicology. The active ingredient used in the commercial antifoulant SeaNine 211, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) was employed as the positive control. Adult marine medaka (4-month-old) were exposed to various concentrations of butenolide or DCOIT for 28 days and then depurated in clean seawater for 14 days (recovery). A suite of sensitive biomarkers, including hepatic oxidative stress, neuronal signal transmission, endocrine disruption, and reproductive function, was used to measure significant biological effects induced by the chemicals. Compared to DCOIT, chronic exposure to butenolide induced a lower extent of oxidative stress in the liver of male and female medaka. Furthermore, butenolide-exposed fish could recover faster from oxidative stress than fish exposed to DCOIT. Regarding neurotransmission, DCOIT significantly inhibited acetylcholinesterase (AChE) activity in the brain of both male and female medaka, whereas this was not significant for butenolide. In addition, plasma estradiol (E{sub 2}) level was elevated and testosterone (T) level was decreased in male medaka exposed to DCOIT. This greatly imbalanced sex hormones ratio (E{sub 2}/T) in exposed males, indicating that DCOIT is a potent endocrine disruptive chemical. In contrast, butenolide induced only moderate effects on sex hormone levels in exposed males, which could be

  7. Comparative safety of the antifouling compound butenolide and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) to the marine medaka (Oryzias melastigma)

    International Nuclear Information System (INIS)

    Chen, Lianguo; Ye, Rui; Xu, Ying; Gao, Zhaoming; Au, Doris W.T.; Qian, Pei-Yuan

    2014-01-01

    Highlights: • Adverse effects of antifouling compound butenolide were studied using marine medaka. • The active ingredient in SeaNine 211, DCOIT, was employed as positive control. • Butenolide induced transient, reversible biological effects on marine medaka. • Lower toxicity of butenolide on marine biota highlights its promising application. • The increased sensitivity of male medaka addresses the gender difference. - Abstract: This study evaluated the potential adverse effects of butenolide, a promising antifouling compound, using the marine medaka (Oryzias melastigma), a model fish for marine ecotoxicology. The active ingredient used in the commercial antifoulant SeaNine 211, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) was employed as the positive control. Adult marine medaka (4-month-old) were exposed to various concentrations of butenolide or DCOIT for 28 days and then depurated in clean seawater for 14 days (recovery). A suite of sensitive biomarkers, including hepatic oxidative stress, neuronal signal transmission, endocrine disruption, and reproductive function, was used to measure significant biological effects induced by the chemicals. Compared to DCOIT, chronic exposure to butenolide induced a lower extent of oxidative stress in the liver of male and female medaka. Furthermore, butenolide-exposed fish could recover faster from oxidative stress than fish exposed to DCOIT. Regarding neurotransmission, DCOIT significantly inhibited acetylcholinesterase (AChE) activity in the brain of both male and female medaka, whereas this was not significant for butenolide. In addition, plasma estradiol (E 2 ) level was elevated and testosterone (T) level was decreased in male medaka exposed to DCOIT. This greatly imbalanced sex hormones ratio (E 2 /T) in exposed males, indicating that DCOIT is a potent endocrine disruptive chemical. In contrast, butenolide induced only moderate effects on sex hormone levels in exposed males, which could be gradually

  8. Comparative genomics of the marine bacterial genus Glaciecola reveals the high degree of genomic diversity and genomic characteristic for cold adaptation.

    Science.gov (United States)

    Qin, Qi-Long; Xie, Bin-Bin; Yu, Yong; Shu, Yan-Li; Rong, Jin-Cheng; Zhang, Yan-Jiao; Zhao, Dian-Li; Chen, Xiu-Lan; Zhang, Xi-Ying; Chen, Bo; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2014-06-01

    To what extent the genomes of different species belonging to one genus can be diverse and the relationship between genomic differentiation and environmental factor remain unclear for oceanic bacteria. With many new bacterial genera and species being isolated from marine environments, this question warrants attention. In this study, we sequenced all the type strains of the published species of Glaciecola, a recently defined cold-adapted genus with species from diverse marine locations, to study the genomic diversity and cold-adaptation strategy in this genus.The genome size diverged widely from 3.08 to 5.96 Mb, which can be explained by massive gene gain and loss events. Horizontal gene transfer and new gene emergence contributed substantially to the genome size expansion. The genus Glaciecola had an open pan-genome. Comparative genomic research indicated that species of the genus Glaciecola had high diversity in genome size, gene content and genetic relatedness. This may be prevalent in marine bacterial genera considering the dynamic and complex environments of the ocean. Species of Glaciecola had some common genomic features related to cold adaptation, which enable them to thrive and play a role in biogeochemical cycle in the cold marine environments.

  9. Using flow cytometry for counting natural planktonic bacteria and understanding the structure of planktonic bacterial communities

    Directory of Open Access Journals (Sweden)

    Josep M. Gasol

    2000-06-01

    Full Text Available Flow cytometry is rapidly becoming a routine methodology in aquatic microbial ecology. The combination of simple to use bench-top flow cytometers and highly fluorescent nucleic acid stains allows fast and easy determination of microbe abundance in the plankton of lakes and oceans. The different dyes and protocols used to stain and count planktonic bacteria as well as the equipment in use are reviewed, with special attention to some of the problems encountered in daily routine practice such as fixation, staining and absolute counting. One of the main advantages of flow cytometry over epifluorescence microscopy is the ability to obtain cell-specific measurements in large numbers of cells with limited effort. We discuss how this characteristic has been used for differentiating photosynthetic from non-photosynthetic prokaryotes, for measuring bacterial cell size and nucleic acid content, and for estimating the relative activity and physiological state of each cell. We also describe how some of the flow cytometrically obtained data can be used to characterize the role of microbes on carbon cycling in the aquatic environment and we prospect the likely avenues of progress in the study of planktonic prokaryotes through the use of flow cytometry.

  10. Composition and structure of managed pine stands compared to reference longleaf pine sites on Marine Corps Base Camp Lejeune, North Carolina

    Science.gov (United States)

    Joan L. Walker; Andrea M. Silletti; Susan Cohen

    2010-01-01

    We sampled the ground layer of 28 pine plantations to compare with ecological reference sites at Marine Corps Base, Camp Lejeune (MCBCL), NC. Plantations were ≥ 18 years old and had been burned within the previous year. Pines had been hand-planted on beds or fl at-planted, and the plantations were burned every 3 to 4 years after age 7. Data from 39 reference sites were...

  11. Resting Stage of Plankton Diversity from Singapore Coastal Water: Implications for Harmful Algae Blooms and Coastal Management.

    Science.gov (United States)

    Trottet, Aurore; Wilson, Bryan; Sew Wei Xin, Genevieve; George, Christaline; Casten, Lemuel; Schmoker, Claire; Rawi, Nurul Syazana Binte Modh; Chew Siew, Moon; Larsen, Ole; Eikaas, Hans S; Tun, Karenne; Drillet, Guillaume

    2018-02-01

    Resting strategies of planktonic organisms are important for the ecological processes of coastal waters and their impacts should be taken into consideration in management of water bodies used by multiple industries. We combined different approaches to evaluate the importance of resting stages in Singapore coastal waters. We used molecular approaches to improve the knowledge on Singapore biodiversity, we sampled and extracted cysts from sediments to evaluate the density of resting stages in Johor Strait, and we compared systematically information on Singapore planktonic biodiversity to existing published information on resting stages from these reported organisms. This is the first study evaluating the importance of resting stages in Singapore waters. Above 120 species reported in Singapore are known to produce resting stages though no previous work has ever been done to evaluate the importance of these strategies in these waters. The results from the resting stage survey confirmed 0.66 to 5.34 cyst g -1 dry weight sediment were present in the Johor Strait suggesting that cysts may be flushed by tidal currents into and out of the strait regularly. This also suggest that the blooms occurring in Singapore are likely due to secondary growth of Harmful Algae Bloom species in the water rather than from direct germination of cysts from sediment. Finally, we discuss the importance of these resting eggs for three main national industries in Singapore (shipping, marine aquaculture and provision of drinking water through seawater desalination). We argue that this study will serve as a baseline for some of the future management of Singapore waters.

  12. A comparative study of the contamination of some marine burrower invertebrates by cobalt 60 and cesium 137

    International Nuclear Information System (INIS)

    Amiard-Triquet, C.

    1975-01-01

    Experments were carried out with species whose mode of life is characterized by close contact with the sediments; they represent different zoological groups: an Annelid (Arenicola marina L.), an Echinoderm (Echinocardium cordatum Pennant) and two Lamellibranchs (Scrobicularia plana da Costa, Macoma balthica L.). The data obtained indicate that main vector of contamination of benthic marine invertebrates is water. The main part of these organisms in the sedimentary zone would be the redistribution, within the sediment, of radioelements adsorbed on the surface [fr

  13. Comparing differential tolerance of native and non-indigenous marine species to metal pollution using novel assay techniques

    International Nuclear Information System (INIS)

    Piola, Richard F.; Johnston, Emma L.

    2009-01-01

    Recent research suggests anthropogenic disturbance may disproportionately advantage non-indigenous species (NIS), aiding their establishment within impacted environments. This study used novel laboratory- and field-based toxicity testing to determine whether non-indigenous and native bryozoans (common within marine epibenthic communities worldwide) displayed differential tolerance to the common marine pollutant copper (Cu). In laboratory assays on adult colonies, NIS showed remarkable tolerance to Cu, with strong post-exposure recovery and growth. In contrast, native species displayed negative growth and reduced feeding efficiency across most exposure levels. Field transplant experiments supported laboratory findings, with NIS growing faster under Cu conditions. In field-based larval assays, NIS showed strong recruitment and growth in the presence of Cu relative to the native species. We suggest that strong selective pressures exerted by the toxic antifouling paints used on transport vectors (vessels), combined with metal contamination in estuarine environments, may result in metal tolerant NIS advantaged by anthropogenically modified selection regimes. - Greater tolerance to pollutants in marine NIS may increase the risk of invasion in port and harbours worldwide by providing a competitive advantage over native taxa.

  14. Evolution of a Planktonic Foraminifer during Environmental Changes in the Tropical Oceans.

    Science.gov (United States)

    Ujiié, Yurika; Ishitani, Yoshiyuki

    2016-01-01

    Ecological adaptation to environmental changes is a strong driver of evolution, enabling speciation of pelagic plankton in the open ocean without the presence of effective physical barriers to gene flow. The tropical ocean environment, which plays an important role in shaping marine biodiversity, has drastically and frequently changed since the Pliocene. Nevertheless, the evolutionary history of tropical pelagic plankton has been poorly understood, as phylogeographic investigations are still in the developing state and paleontological approaches are insufficient to obtain a sequential record from the deep-sea sediments. The planktonic foraminifer Pulleniatina obliquiloculata is widely distributed in the tropical area throughout the world's oceans, and its phylogeography is well established. It is thus one of the best candidates to examine how past environmental changes may have shifted the spatial distribution and affected the diversification of tropical pelagic plankton. Such an examination requires the divergence history of the planktonic foraminifers, yet the gene marker (partial small subunit (SSU) rDNA) previously used for phylogeographic studies was not powerful enough to achieve a high accuracy in estimating the divergence times. The present study focuses on improving the precision of divergence time estimates for the splits between sibling species (genetic types) of planktonic foraminifers by increasing the number of genes as well as the number of nucleotide bases used for molecular clock estimates. We have amplified the entire coding regions of two ribosomal RNA genes (SSU rDNA and large subunit (LSU) rDNA) of three genetic types of P. obliquiloculata and two closely related species for the first time and applied them to the Bayesian relaxed clock method. The comparison of the credible intervals of the four datasets consisting either of sequences of the partial SSU rDNA, the complete SSU rDNA, LSU rDNA, or a combination of both genes (SSU+LSU) clearly

  15. Otters, Marine

    Science.gov (United States)

    Estes, James A.; Bodkin, James L.; Ben-David, M.; Perrin, William F.; Würsing, Bernd; Thewissen, J.G.M.

    2009-01-01

    The otters (Mustelidae; Lutrinae) provide an exceptional perspective into the evolution of marine living by mammals. Most extant marine mammals (e.g. the cetaceans, pinnipeds, and sirenians) have been so highly modified by long periods of selection for life in the sea that they bear little resemblance to their terrestrial ancestors. Marine otters, in contrast, are more recent expatriates from freshwater habitats and some species still live in both environments. Contrasts among species within the otters, and among the otters, terrestrial mammals, and the more highly adapted pinnipeds and cetaceans provide powerful insights into mammalian adaptations to life in the sea (Estes, 1989). Among the marine mammals, sea otters (Enhydra lutris, Fig. 1) provide the clearest understanding of consumer-induced effects on ecosystem function. This is due in part to opportunities provided by history and in part to the relative ease with which shallow coastal systems where sea otters live can be observed and studied. Although more difficult to study than sea otters, other otter species reveal the connectivity among the marine, freshwater, and terrestrial systems. These three qualities of the otters – their comparative biology, their role as predators, and their role as agents of ecosystem connectivity – are what make them interesting to marine mammalogy.The following account provides a broad overview of the comparative biology and ecology of the otters, with particular emphasis on those species or populations that live in the sea. Sea otters are features prominently, in part because they live exclusively in the sea whereas other otters have obligate associations with freshwater and terrestrial environments (Kenyon, 1969; Riedman and Estes, 1990).

  16. Influence of ocean acidification on plankton community structure during a winter-to-summer succession: An imaging approach indicates that copepods can benefit from elevated CO2 via indirect food web effects

    Science.gov (United States)

    Taucher, Jan; Haunost, Mathias; Boxhammer, Tim; Bach, Lennart T.; Algueró-Muñiz, María; Riebesell, Ulf

    2017-01-01

    Plankton communities play a key role in the marine food web and are expected to be highly sensitive to ongoing environmental change. Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. These changes–summarized by the term ocean acidification (OA)–can significantly affect the physiology of planktonic organisms. However, studies on the response of entire plankton communities to OA, which also include indirect effects via food-web interactions, are still relatively rare. Thus, it is presently unclear how OA could affect the functioning of entire ecosystems and biogeochemical element cycles. In this study, we report from a long-term in situ mesocosm experiment, where we investigated the response of natural plankton communities in temperate waters (Gullmarfjord, Sweden) to elevated CO2 concentrations and OA as expected for the end of the century (~760 μatm pCO2). Based on a plankton-imaging approach, we examined size structure, community composition and food web characteristics of the whole plankton assemblage, ranging from picoplankton to mesozooplankton, during an entire winter-to-summer succession. The plankton imaging system revealed pronounced temporal changes in the size structure of the copepod community over the course of the plankton bloom. The observed shift towards smaller individuals resulted in an overall decrease of copepod biomass by 25%, despite increasing numerical abundances. Furthermore, we observed distinct effects of elevated CO2 on biomass and size structure of the entire plankton community. Notably, the biomass of copepods, dominated by Pseudocalanus acuspes, displayed a tendency towards elevated biomass by up to 30–40% under simulated ocean acidification. This effect was significant for certain copepod size classes and was most likely driven by CO2-stimulated responses of primary producers and a complex interplay of trophic interactions that allowed this

  17. Production of live prey for marine fish larvae

    OpenAIRE

    Kraul, S

    1989-01-01

    Tropical marine fish larvae vary in their requirements for live planktonic food. Selection of live prey species for culture depends on larval size and larval tolerance of water quality. This report describes some of the cultured prey species, and their uses and limits as effective food for fish larvae. Methods are presented for the culture of phytoplankton, rotifers, copepods, and other live feeds.

  18. Recent planktonic foraminifera from the sediment off Karwar and Mangalore

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.; Guptha, M.V.S.

    Eleven samples collected from the shelf-slope regions off Karwar and mangalore transects of the Arabian Sea, yielded fifteen planktonic foraminiferal species, which are identified and described. There is a progressive increase in the percentage...

  19. GLOBEC NEP Vertical Plankton Tow (VPT) Data, 1997-2001

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GLOBEC (GLOBal Ocean ECosystems Dynamics) NEP (Northeast Pacific) California Current Program Vertical Plankton Tow (VPT) Data For more information, see...

  20. GLOBEC NEP MOCNESS Plankton (MOC1) Data, 2000-2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GLOBEC (GLOBal Ocean ECosystems Dynamics) NEP (Northeast Pacific) California Current Program MOCNESS Plankton (MOC1) Data The MOCNESS is based on the Tucker Trawl...

  1. Living planktonic foraminifera of the Wadge bank, Northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Panikkar, B.M.; Kutty, M.K.

    Twenty three species of living planktonic Foraminifera belonging to 11 genera have been studied from the Wadge Bank area off southern tip of the Indian peninsula. The fauna is characterized by species such as Globigerinoides conglobatus, G...

  2. Planktonic algae and cyanoprokaryotes as indicators of ecosystem ...

    African Journals Online (AJOL)

    Planktonic algae and cyanoprokaryotes as indicators of ecosystem quality in the Mooi River system in the North-West Province, South Africa. ... is important for maintaining the quality of potable water of Potchefstroom and surrounding areas.

  3. Bacteriophage-antibiotic synergism to control planktonic and biofilm ...

    African Journals Online (AJOL)

    Bacteriophage-antibiotic synergism to control planktonic and biofilm producing clinical isolates of Pseudomonas aeruginosa. Amina Amal Mahmoud Nouraldin, Manal Mohammad Baddour, Reem Abdel Hameed Harfoush, Sara AbdelAziz Mohamed Essa ...

  4. New perspectives on the functioning and evolution of photosymbiosis in plankton

    Science.gov (United States)

    Decelle, Johan

    2013-01-01

    Photosymbiosis is common and widely distributed in plankton and is considered to be beneficial for both partners (mutualism). Such intimate associations involving heterotrophic hosts and microalgal symbionts have been extensively studied in coral reefs, but in the planktonic realm, the ecology and evolution of photosymbioses remain poorly understood. Acantharia (Radiolaria) are ubiquitous and abundant heterotrophic marine protists, many of which host endosymbiotic microalgae. Two types of photosymbiosis involving acantharians have recently been described using molecular techniques: one found in a single acantharian species involving multiple microalgal partners (dinoflagellates and haptophytes), and the other observed in more than 25 acantharian species exclusively living with the haptophyte Phaeocystis. Contrary to most benthic and terrestrial mutualistic symbioses, these symbiotic associations share the common feature of involving symbionts that are abundant in their free-living stage. We propose a hypothetical framework that may explain this original mode of symbiosis, and discuss the ecological and evolutionary implications. We suggest that photosymbiosis in Acantharia, and probably in other planktonic hosts, may not be a mutualistic relationship but rather an “inverted parasitism,” from which only hosts seem to benefit by sequestrating and exploiting microalgal cells. The relatively small population size of microalgae in hospite would prevent reciprocal evolution that can select uncooperative symbionts, therefore making this horizontally-transmitted association stable over evolutionary time. The more we learn about the diversity of life and the structure of genomes, the more it appears that much of the evolution of biodiversity is about the manipulation of other species—to gain resources and, in turn, to avoid being manipulated (John Thompson, 1999). PMID:23986805

  5. New perspectives on the functioning and evolution of photosymbiosis in plankton: Mutualism or parasitism?

    Science.gov (United States)

    Decelle, Johan

    2013-07-01

    Photosymbiosis is common and widely distributed in plankton and is considered to be beneficial for both partners (mutualism). Such intimate associations involving heterotrophic hosts and microalgal symbionts have been extensively studied in coral reefs, but in the planktonic realm, the ecology and evolution of photosymbioses remain poorly understood. Acantharia (Radiolaria) are ubiquitous and abundant heterotrophic marine protists, many of which host endosymbiotic microalgae. Two types of photosymbiosis involving acantharians have recently been described using molecular techniques: one found in a single acantharian species involving multiple microalgal partners (dinoflagellates and haptophytes), and the other observed in more than 25 acantharian species exclusively living with the haptophyte Phaeocystis. Contrary to most benthic and terrestrial mutualistic symbioses, these symbiotic associations share the common feature of involving symbionts that are abundant in their free-living stage. We propose a hypothetical framework that may explain this original mode of symbiosis, and discuss the ecological and evolutionary implications. We suggest that photosymbiosis in Acantharia, and probably in other planktonic hosts, may not be a mutualistic relationship but rather an "inverted parasitism," from which only hosts seem to benefit by sequestrating and exploiting microalgal cells. The relatively small population size of microalgae in hospite would prevent reciprocal evolution that can select uncooperative symbionts, therefore making this horizontally-transmitted association stable over evolutionary time. The more we learn about the diversity of life and the structure of genomes, the more it appears that much of the evolution of biodiversity is about the manipulation of other species-to gain resources and, in turn, to avoid being manipulated (John Thompson, 1999).

  6. Modeling marine surface microplastic transport to assess optimal removal locations

    Science.gov (United States)

    Sherman, Peter; van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres.

  7. Modeling marine surface microplastic transport to assess optimal removal locations

    International Nuclear Information System (INIS)

    Sherman, Peter; Van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres. (letter)

  8. Life spans of planktonic foraminifers: New sight through sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Saraswat, R.; Mazumder, A.

    ), indicated by black arrows are remarkably present for all three trap locations. (Modified after Curry et l.t 1992). 2002; Eguchi, Ujiie, Kawahata and Taira 2003), (ii) all the traps can not stop functioning simultaneously and that for the same time... estimates of the life spans of planktonic foraminifera based on extrapolation of lab culture observations. According to Be et al (1981), an inverse relationship exists between feeding frequency and survival time, and that planktonic foraminifers under...

  9. Influence of UVB radiation on the lethal and sublethal toxicity of dispersed crude oil to planktonic copepod nauplii.

    Science.gov (United States)

    Almeda, Rodrigo; Harvey, Tracy E; Connelly, Tara L; Baca, Sarah; Buskey, Edward J

    2016-06-01

    Toxic effects of petroleum to marine zooplankton have been generally investigated using dissolved petroleum hydrocarbons and in the absence of sunlight. In this study, we determined the influence of natural ultraviolet B (UVB) radiation on the lethal and sublethal toxicity of dispersed crude oil to naupliar stages of the planktonic copepods Acartia tonsa, Temora turbinata and Pseudodiaptomus pelagicus. Low concentrations of dispersed crude oil (1 μL L(-1)) caused a significant reduction in survival, growth and swimming activity of copepod nauplii after 48 h of exposure. UVB radiation increased toxicity of dispersed crude oil by 1.3-3.8 times, depending on the experiment and measured variables. Ingestion of crude oil droplets may increase photoenhanced toxicity of crude oil to copepod nauplii by enhancing photosensitization. Photoenhanced sublethal toxicity was significantly higher when T. turbinata nauplii were exposed to dispersant-treated oil than crude oil alone, suggesting that chemical dispersion of crude oil may promote photoenhanced toxicity to marine zooplankton. Our results demonstrate that acute exposure to concentrations of dispersed crude oil and dispersant (Corexit 9500) commonly found in the sea after oil spills are highly toxic to copepod nauplii and that natural levels of UVB radiation substantially increase the toxicity of crude oil to these planktonic organisms. Overall, this study emphasizes the importance of considering sunlight in petroleum toxicological studies and models to better estimate the impact of crude oil spills on marine zooplankton. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. The background to the proposition that plankton be used as food in the United Kingdom during the Second World War.

    Science.gov (United States)

    Moore, P G

    2011-01-01

    Food shortages, particularly of proteins, in Britain during the Second World War led to the suggestion re-surfacing that marine plankton might be harvested on an industrial scale first as human food, then turning to its potential use as a supplement to stock and poultry feed. The notion emanated in the United Kingdom from Sir John Graham Kerr, at Glasgow University. He encouraged Alister Hardy, at Hull, to develop the idea and the natural testing ground was the Clyde Sea Area (given the extensive history of plankton research at Millport). Unpublished documents from the archives of the Scottish Association for Marine Science shed new light on the interactions behind the scenes of this project between Kerr, Hardy and the Millport Marine Station's then director, Richard Elmhirst. Elmhirst, who was sceptical about the feasibility of the plan from the outset, went along with it; not least as a way of attracting welcome research funding during lean times but also, doubtless, regarding it as his patriotic duty in case the proposal proved worthwhile.

  11. Environmental Impacts—Marine Ecosystems

    DEFF Research Database (Denmark)

    Brander, Keith; Ottersen, Geir; Bakker, J.P.

    2016-01-01

    This chapter presents a review of what is known about the impacts of climate change on the biota (plankton, benthos, fish, seabirds and marine mammals) of the North Sea. Examples show how the changing North Sea environment is affecting biological processes and organisation at all scales, including...... the physiology, reproduction, growth, survival, behaviour and transport of individuals; the distribution, dynamics and evolution of populations; and the trophic structure and coupling of ecosystems. These complex responses can be detected because there are detailed long-term biological and environmental records...

  12. Ecological effects of scrubber water discharge on coastal plankton: Potential synergistic effects of contaminants reduce survival and feeding of the copepod Acartia tonsa

    DEFF Research Database (Denmark)

    Koski, Marja; Stedmon, Colin; Trapp, Stefan

    2017-01-01

    and hydrocarbons. We investigated 1) the threshold concentrations of scrubber discharge water for survival, feeding and reproduction of the copepod Acartia tonsa, 2) whether the effects depend on the exposure route and 3) whether exposure to discharge water can be detected in field-collected organisms. A direct...... constituents could have synergistic effects on plankton productivity and bioaccumulation of metals, although the effects will depend on their dilution in the marine environment....

  13. Worldwide Genotyping in the Planktonic Foraminifer Globoconella inflata: Implications for Life History and Paleoceanography

    Science.gov (United States)

    Morard, Raphaël; Quillévéré, Frédéric; Douady, Christophe J.; de Vargas, Colomban; de Garidel-Thoron, Thibault; Escarguel, Gilles

    2011-01-01

    The planktonic foraminiferal morpho-species Globoconella inflata is widely used as a stratigraphic and paleoceanographic index. While G. inflata was until now regarded as a single species, we show that it rather constitutes a complex of two pseudo-cryptic species. Our study is based on SSU and ITS rDNA sequence analyses and genotyping of 497 individuals collected at 49 oceanic stations covering the worldwide range of the morpho-species. Phylogenetic analyses unveil the presence of two divergent genotypes. Type I inhabits transitional and subtropical waters of both hemispheres, while Type II is restricted to the Antarctic subpolar waters. The two genetic species exhibit a strictly allopatric distribution on each side of the Antarctic Subpolar Front. On the other hand, sediment data show that G. inflata was restricted to transitional and subtropical environments since the early Pliocene, and expanded its geographic range to southern subpolar waters ∼700 kyrs ago, during marine isotopic stage 17. This datum may correspond to a peripatric speciation event that led to the partition of an ancestral genotype into two distinct evolutionary units. Biometric measurements performed on individual G. inflata from plankton tows north and south of the Antarctic Subpolar Front indicate that Types I and II display slight but significant differences in shell morphology. These morphological differences may allow recognition of the G. inflata pseudo-cryptic species back into the fossil record, which in turn may contribute to monitor past movements of the Antarctic Subpolar Front during the middle and late Pleistocene. PMID:22028935

  14. The response of calcifying plankton to climate change in the Pliocene

    Directory of Open Access Journals (Sweden)

    C. V. Davis

    2013-09-01

    Full Text Available As a result of anthropogenic pCO2 increases, future oceans are growing warmer and lower in pH and oxygen, conditions that are likely to impact planktic communities. Past intervals of elevated and changing pCO2 and temperatures can offer a glimpse into the response of marine calcifying plankton to changes in surface oceans under conditions similar to those projected for the future. Here we present new records of planktic foraminiferal and coccolith calcification (weight and size from Deep Sea Drilling Project Site 607 (mid-North Atlantic and Ocean Drilling Program Site 999 (Caribbean Sea from the Pliocene, the last time that pCO2 was similar to today, and extending through a global cooling event into the intensification of Northern Hemisphere glaciation (3.3 to 2.6 million years ago. Test weights of both surface-dwelling Foraminifera Globigerina bulloides and thermocline-dwelling Foraminifera Globorotalia puncticulata vary with a potential link to regional temperature variation in the North Atlantic, whereas in the tropics Globigerinoides ruber test weight remains stable. In contrast, reticulofenestrid coccoliths show a narrowing size range and a decline in the largest lith diameters over this interval. Our results suggest no major changes in plankton calcite production during the high pCO2 Pliocene or during the transition into an icehouse world.

  15. Standing out from the crowd: Spotting your targets in a mixed plankton sample.

    Science.gov (United States)

    Harada, Alice E; Burton, Ronald S

    2017-11-01

    The diversity of marine organisms is staggering, and this fact is readily appreciated by microscopic examination of the contents of a plankton net after a short tow across the ocean surface. Although this diversity is beautiful, it can present a significant problem for those seeking to extract information about a single species of interest. Enumeration of the eggs and larvae of a specific target species can provide a quantitative window into reproductive dynamics that are of great use for fisheries stock assessment and management. But how do you efficiently sort through the mass of plankton and identify target species' eggs and larvae that may be morphologically indistinguishable from those of a number of other local species? In this issue of Molecular Ecology Resources, Oxley et al. () describe an innovative in situ hybridization (ISH) approach that successfully solves this important problem and opens an exciting new avenue to ichthyoplankton analysis that may be widely adopted by both fish ecologists and fisheries managers. © 2017 John Wiley & Sons Ltd.

  16. Assembling the Marine Metagenome, One Cell at a Time

    Energy Technology Data Exchange (ETDEWEB)

    Woyke, Tanja; Xie, Gary; Copeland, Alex; Gonzalez, Jose M.; Han, Cliff; Kiss, Hajnalka; Saw, Jimmy H.; Senin, Pavel; Yang, Chi; Chatterji, Sourav; Cheng, Jan-Fang; Eisen, Jonathan A.; Sieracki, Michael E.; Stepanauskas, Ramunas

    2010-06-24

    The difficulty associated with the cultivation of most microorganisms and the complexity of natural microbial assemblages, such as marine plankton or human microbiome, hinder genome reconstruction of representative taxa using cultivation or metagenomic approaches. Here we used an alternative, single cell sequencing approach to obtain high-quality genome assemblies of two uncultured, numerically significant marine microorganisms. We employed fluorescence-activated cell sorting and multiple displacement amplification to obtain hundreds of micrograms of genomic DNA from individual, uncultured cells of two marine flavobacteria from the Gulf of Maine that were phylogenetically distant from existing cultured strains. Shotgun sequencing and genome finishing yielded 1.9 Mbp in 17 contigs and 1.5 Mbp in 21 contigs for the two flavobacteria, with estimated genome recoveries of about 91percent and 78percent, respectively. Only 0.24percent of the assembling sequences were contaminants and were removed from further analysis using rigorous quality control. In contrast to all cultured strains of marine flavobacteria, the two single cell genomes were excellent Global Ocean Sampling (GOS) metagenome fragment recruiters, demonstrating their numerical significance in the ocean. The geographic distribution of GOS recruits along the Northwest Atlantic coast coincided with ocean surface currents. Metabolic reconstruction indicated diverse potential energy sources, including biopolymer degradation, proteorhodopsin photometabolism, and hydrogen oxidation. Compared to cultured relatives, the two uncultured flavobacteria have small genome sizes, few non-coding nucleotides, and few paralogous genes, suggesting adaptations to narrow ecological niches. These features may have contributed to the abundance of the two taxa in specific regions of the ocean, and may have hindered their cultivation. We demonstrate the power of single cell DNA sequencing to generate reference genomes of uncultured

  17. Benthic foraminifera in the plankton following storms: what does this mean for (palaeo)-ecological interpretations?

    Science.gov (United States)

    Hart, Malcolm; Molina, Giulia; Smart, Christopher; Widdicombe, Claire

    2017-04-01

    The Western Channel Observatory was established by the Natural Environment Research Council (NERC), with Plymouth Marine Laboratory managing the two autonomous buoys that are located to the south of Plymouth in the English Channel (Stations L4 and E1): see Smyth et al. (2015). These two locations are now monitored continually and there is regular sampling of the water column and the sea floor at both locations. At Station L4, despite being in waters with a depth of 50 m, benthic foraminifera are regularly found in the surface water plankton samples. Some of these benthic foraminifera contain algal symbionts, indicating that they may be living at the time of capture. If benthic foraminifera can be entrained in the water column, while still living, then this provides a mechanism for 'migration' that is much more rapid and efficient than the rate at which protists could migrate within, or on, the sediment surface. Recolonization by foraminifera, following disturbance, could well be facilitated by this mechanism which has only rarely been reported in the literature (e.g., Murray, 1965). It is clearly limited to depths impacted by fair weather ( 30 m) or storm wave base (80 - 100 m). Data gathered during winter 2015-2016 certainly indicate that, following storm events, the larger the number of benthic foraminifera in the plankton tows and the greater their overall size. Some of the individuals being observed appear to contain sediment, indicating that they have been picked up from the sediment surface and, despite their greater weight, have still been transported into the plankton. Using data from the nearby sea area, off-shore and within Plymouth Sound, we are trying to ascertain if the recorded assemblage is from the L4 area, or whether they have been transported out from shallower-water environments, possibly assisted by increased run-off caused by heavy rainfall (associated with the storms). Clearly, re-distribution of foraminifera in the environment might make

  18. Negative consequences of glacial turbidity for the survival of freshwater planktonic heterotrophic flagellates.

    Science.gov (United States)

    Sommaruga, Ruben; Kandolf, Georg

    2014-02-17

    Heterotrophic (phagotrophic) flagellates are key components of planktonic food webs in freshwater and marine ecosystems because they are the main consumers of bacteria. Although they are ubiquitous in aquatic ecosystems, they were numerically undetectable in turbid glacier-fed lakes. Here we show that glacial particles had negative effects on the survival and growth of heterotrophic flagellates. The effect of glacial particles was concentration-dependent and was caused by their interference with bacterial uptake rather than by physical damage. These results are the first to reveal why establishment of heterotrophic flagellates populations is hindered in very turbid glacial lakes. Because glaciers are vanishing around the world, recently formed turbid meltwater lakes represent an excellent opportunity to understand the environmental conditions that probably shaped the establishment of lake communities at the end of the last glaciation.

  19. Circadian cycles in growth and feeding rates of heterotrophic protist plankton

    DEFF Research Database (Denmark)

    Jakobsen, Hans Henrik; Strom, S.L.

    2004-01-01

    Growth and feeding rates of four species of planktonic marine heterotrophic protists showed pronounced diel cycles. In most cases, rates were higher during the day and lower at night. However, for the ciliate Strobilidium sp., growth was highest at night. In another ciliate species, Balanion...... comatum, no day-night difference in growth and feeding rates was found. Maintenance of day-night rate differences during 24-h exposures to continuous darkness demonstrated that most of these protists had circadian cycles. The heterotrophic dinoflagellate Oxyrrhis marina exhibited a clear irradiance...... to culturing in a day: night light cycle in O. marina and found that resetting the circadian cycle in this dinoflagellate temporarily arrested growth and feeding. We suggest that protists use a time-integrated light threshold rather than an instantaneous irradiance to maintain the circadian cell cycle...

  20. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    International Nuclear Information System (INIS)

    Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

    2016-01-01

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  1. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

    2016-06-15

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  2. Experimental assessment of cumulative temperature and UV-B radiation effects on Mediterranean plankton metabolism

    KAUST Repository

    Garcia-Corral, Lara S.

    2015-07-07

    The Mediterranean Sea is a vulnerable region for climate change, warming at higher rates compare to the global ocean. Warming leads to increased stratification of the water column and enhanced the oligotrophic nature of the Mediterranean Sea. The oligotrophic waters are already highly transparent, however, exposure of Mediterranean plankton to ultraviolet radiation (UV-B and UV-A) may increase further if the waters become more oligotrophic, thereby, allowing a deeper UV radiation penetration and likely enhancing impacts to biota. Here we experimentally elucidate the cumulative effects of warming and natural UV-B radiation on the net community production (NCP) of plankton communities. We conducted five experiments at monthly intervals, from June to October 2013, and evaluated the responses of NCP to ambient UV-B radiation and warming (+3°C), alone and in combination, in a coastal area of the northwest Mediterranean Sea. UV-B radiation and warming lead to reduced NCP and resulted in a heterotrophic (NCP < 0) metabolic balance. Both UV-B radiation and temperature, showed a significant individual effect in NCP across treatments and time. However, their joint effect showed to be synergistic as the interaction between them (UV × Temp) was statistically significant in most of the experiments performed. Our results showed that both drivers, would affect the gas exchange of CO2−O2 from and to the atmosphere and the role of plankton communities in the Mediterranean carbon cycle.

  3. Experimental assessment of cumulative temperature and UV-B radiation effects on Mediterranean plankton metabolism

    Directory of Open Access Journals (Sweden)

    Lara S. eGarcia-Corral

    2015-07-01

    Full Text Available The Mediterranean Sea is a vulnerable region for climate change, warming at higher rates compare to the global ocean. Warming leads to increased stratification of the water column and enhanced the oligotrophic nature of the Mediterranean Sea. The oligotrophic waters are already highly transparent, however, exposure of Mediterranean plankton to ultraviolet radiation (UV-B and UV-A may increase further if the waters become more oligotrophic, thereby, allowing a deeper UV radiation penetration and likely enhancing impacts to biota.Here we experimentally elucidate the cumulative effects of warming and natural UV-B radiation on the net community production (NCP of plankton communities. We conducted five experiments at monthly intervals, from June to October 2013, and evaluated the responses of NCP to ambient UV-B radiation and warming (+3ºC, alone and in combination, in a coastal area of the northwest Mediterranean Sea. UV-B radiation and warming lead to reduced net community production and resulted in a heterotrophic (NCP<0 metabolic balance. Both UV-B radiation and temperature, showed a significant individual effect in NCP across treatments and time. However, their joint effect showed to be synergistic as the interaction between them (UV x Temp was statistically significant in most of the experiments performed. Our results showed that both drivers, would affect the gas exchange of CO2-O2 from and to the atmosphere and the role of plankton communities in the Mediterranean carbon cycle

  4. Planktonic growth and biofilm formation profiles in Candida haemulonii species complex.

    Science.gov (United States)

    Ramos, Lívia S; Oliveira, Simone S C; Souto, Xênia M; Branquinha, Marta H; Santos, André L S

    2017-10-01

    Candida haemulonii species complex have emerged as multidrug-resistant yeasts able to cause fungemia worldwide. However, very little is known regarding their physiology and virulence factors. In this context, planktonic growth and biofilm formation of Brazilian clinical isolates of Candida haemulonii (n = 5), Candida duobushaemulonii (n = 4), and Candida haemulonii var. vulnera (n = 3) were reported. Overall, the fungal planktonic growth curves in Sabouraud dextrose broth reached the exponential phase in 48 h at 37°C. All the clinical isolates formed biofilm on polystyrene in a time-dependent event, as judged by the parameters evaluated: biomass (crystal violet staining), metabolic activity (XTT reduction), and extracellular matrix (safranin incorporation). No statistically significant differences were observed when the average measurements among the three Candida species were compared regarding both planktonic and biofilm lifestyles; however, typical isolate-specific differences were clearly noticed in fungal growth kinetics. © The Author 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Effect of water irrigation volume on Capsicum frutescens growth and plankton abundance in aquaponics system

    Science.gov (United States)

    Andriani, Y.; Dhahiyat, Y.; Zahidah; Subhan, U.; Iskandar; Zidni, I.; Mawardiani, T.

    2018-03-01

    This study aimed to understand Capsicum frutescens growth and plankton abundance in aquaponics culture. A Completely Randomized Design (CRD) with six treatments in triplicates comprising of treatment A (positive control using organic liquid fertilizer), B (negative control without fertilizer), C (drip irrigation aquaponics with a water debit of 100 ml/day/plant), D (drip irrigation aquaponics with a water debit of 150 ml/day/plant), E (drip irrigation with a water debit of 200 ml/day/plant), and F (drip irrigation aquaponics with a water debit of 250 ml/day/plant) was applied. The water used in treatments C, D, E, and F contained comet fish feces as fertilizer. C. frutescens growth and plankton abundance were observed. Analysis was conducted using analysis of variance for plant productivity and descriptive analysis for plankton abundance and water quality. The results of this study showed that the highest plant growth was seen in plants receiving F treatment with 50 ml/day drip irrigation. However, no significant difference was found when compared to the positive control with organic artificial fertilizer. Eleven types of phytoplankton and six types of zooplankton were found, with Stanieria sp. as the most abundant phytoplankton and Brachionus sp. and Epistylis sp. as the most abundant zooplanktons.

  6. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    Science.gov (United States)

    Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

    2016-06-01

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  7. Differences in planktonic microbial communities associated with three types of macrophyte stands in a shallow lake.

    Science.gov (United States)

    Mentes, Anikó; Szabó, Attila; Somogyi, Boglárka; Vajna, Balázs; Tugyi, Nóra; Csitári, Bianka; Vörös, Lajos; Felföldi, Tamás

    2018-02-01

    Little is known about how various substances from living and decomposing aquatic macrophytes affect the horizontal patterns of planktonic bacterial communities. Study sites were located within Lake Kolon, which is a freshwater marsh and can be characterised by open-water sites and small ponds with different macrovegetation (Phragmites australis, Nymphea alba and Utricularia vulgaris). Our aim was to reveal the impact of these macrophytes on the composition of the planktonic microbial communities using comparative analysis of environmental parameters, microscopy and pyrosequencing data. Bacterial 16S rRNA gene sequences were dominated by members of phyla Proteobacteria (36%-72%), Bacteroidetes (12%-33%) and Actinobacteria (5%-26%), but in the anoxic sample the ratio of Chlorobi (54%) was also remarkable. In the phytoplankton community, Cryptomonas sp., Dinobryon divergens, Euglena acus and chrysoflagellates had the highest proportion. Despite the similarities in most of the measured environmental parameters, the inner ponds had different bacterial and algal communities, suggesting that the presence and quality of macrophytes directly and indirectly controlled the composition of microbial plankton. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Some trace elements in the waters, marine organisms and sediments of the Adriatic by neutron activation analysis

    International Nuclear Information System (INIS)

    Kosta, L.; Ravnik, V.; Byrne, A.R.; Dermelj, M.; Stirn, J.

    1978-01-01

    A number of investigations of trace elements in the waters, organisms and sediments of the Adriatic, using neutron activation analysis with radiochemical separations are reported. These include studies of Hg in mussels from the Northern Adriatic, of Hg and Se in edible animals from the Rijeka region, and of seven elements (As, Cd, Cu, Hg, Mn, Se and Zn) in marine invertebrates from the Slovene coast. Additionally, plankton, sediment cores and water samples were taken from a grid of stations covering the whole Adriatic and analyzed for 6 to 11 of the trace elements As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Sb and Zn (Hg only in water). Generally, levels found were not indicative of pollution as compared with oceanic samples, but some evidence of locally increased levels was found, especially for Hg. The levels of eleven trace elements in three marine Intercomparison samples prepared by the IAEA Monaco Laboratory are also presented. (T.G.)

  9. Comparative Study on the Effects of Boiling, Steaming, Grilling, Microwaving and Superheated Steaming on Quality Characteristics of Marinated Chicken Steak

    Science.gov (United States)

    Choi, Yun-Sang; Kim, Young-Boong; Jeon, Ki-Hong; Kim, Eun-Mi; Sung, Jung-Min; Kim, Hyun-Wook

    2016-01-01

    The effects of five different cooking methods (boiling, steaming, grilling, microwaving, and superheated steaming) on proximate composition, pH, color, cooking loss, textural properties, and sensory characteristics of chicken steak were studied. Moisture content and lightness value (L*-value) were higher in superheated steam cooked chicken steak than that of the other cooking treatments such as boiling, steaming, grilling and microwaving cooking (pcooked chicken steak was lower than that in the other cooking treatments (pchicken steak cooked using various methods (p>0.05). Among the sensory characteristics, tenderness score, juiciness score and overall acceptability score were the highest for the superheated steam samples (p0.05). These results show that marinated chicken steak treated with superheated steam in a preheated 250℃ oven and 380℃ steam for 5 min until core temperature reached 75℃ improved the quality characteristics and sensory properties the best. Therefore, superheated steam was useful to improve cooked chicken steak. PMID:27499656

  10. Comparative safety of the antifouling compound butenolide and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) to the marine medaka (Oryzias melastigma)

    KAUST Repository

    Chen, Lianguo

    2014-04-01

    This study evaluated the potential adverse effects of butenolide, a promising antifouling compound, using the marine medaka (Oryzias melastigma), a model fish for marine ecotoxicology. The active ingredient used in the commercial antifoulant SeaNine 211, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) was employed as the positive control. Adult marine medaka (4-month-old) were exposed to various concentrations of butenolide or DCOIT for 28 days and then depurated in clean seawater for 14 days (recovery). A suite of sensitive biomarkers, including hepatic oxidative stress, neuronal signal transmission, endocrine disruption, and reproductive function, was used to measure significant biological effects induced by the chemicals. Compared to DCOIT, chronic exposure to butenolide induced a lower extent of oxidative stress in the liver of male and female medaka. Furthermore, butenolide-exposed fish could recover faster from oxidative stress than fish exposed to DCOIT. Regarding neurotransmission, DCOIT significantly inhibited acetylcholinesterase (AChE) activity in the brain of both male and female medaka, whereas this was not significant for butenolide. In addition, plasma estradiol (E2) level was elevated and testosterone (T) level was decreased in male medaka exposed to DCOIT. This greatly imbalanced sex hormones ratio (E2/T) in exposed males, indicating that DCOIT is a potent endocrine disruptive chemical. In contrast, butenolide induced only moderate effects on sex hormone levels in exposed males, which could be gradually recovered during depuration. Moreover, the endocrine disruptive effect induced by butenolide did not affect normal development of offspring. In contrast, DCOIT-exposed fish exhibited a decrease of egg production and impaired reproductive success. Overall, the above findings demonstrated that chronic exposure to butenolide induced transient, reversible biological effect on marine medaka, while DCOIT could impair reproductive success of fish, as

  11. Comparative safety of the antifouling compound butenolide and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) to the marine medaka (Oryzias melastigma).

    Science.gov (United States)

    Chen, Lianguo; Ye, Rui; Xu, Ying; Gao, Zhaoming; Au, Doris W T; Qian, Pei-Yuan

    2014-04-01

    This study evaluated the potential adverse effects of butenolide, a promising antifouling compound, using the marine medaka (Oryzias melastigma), a model fish for marine ecotoxicology. The active ingredient used in the commercial antifoulant SeaNine 211, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) was employed as the positive control. Adult marine medaka (4-month-old) were exposed to various concentrations of butenolide or DCOIT for 28 days and then depurated in clean seawater for 14 days (recovery). A suite of sensitive biomarkers, including hepatic oxidative stress, neuronal signal transmission, endocrine disruption, and reproductive function, was used to measure significant biological effects induced by the chemicals. Compared to DCOIT, chronic exposure to butenolide induced a lower extent of oxidative stress in the liver of male and female medaka. Furthermore, butenolide-exposed fish could recover faster from oxidative stress than fish exposed to DCOIT. Regarding neurotransmission, DCOIT significantly inhibited acetylcholinesterase (AChE) activity in the brain of both male and female medaka, whereas this was not significant for butenolide. In addition, plasma estradiol (E2) level was elevated and testosterone (T) level was decreased in male medaka exposed to DCOIT. This greatly imbalanced sex hormones ratio (E2/T) in exposed males, indicating that DCOIT is a potent endocrine disruptive chemical. In contrast, butenolide induced only moderate effects on sex hormone levels in exposed males, which could be gradually recovered during depuration. Moreover, the endocrine disruptive effect induced by butenolide did not affect normal development of offspring. In contrast, DCOIT-exposed fish exhibited a decrease of egg production and impaired reproductive success. Overall, the above findings demonstrated that chronic exposure to butenolide induced transient, reversible biological effect on marine medaka, while DCOIT could impair reproductive success of fish, as

  12. Radiocarbon dating of planktonic foraminifer shells: A cautionary tale

    Science.gov (United States)

    Mekik, Figen

    2014-01-01

    rate, bioturbation, winnowing, and calcite dissolution produce significant radiocarbon age offsets among multiple species of coexisting planktonic foraminifers and pteropod fragments. We compare the radiocarbon age of foraminifer species and pteropod fragments with estimates of percent calcite dissolved made with a sedimentary proxy (Globorotalia menardii fragmentation index—MFI) to delineate the effect of dissolution on radiocarbon age of foraminifers. Data from two core top transects on the Rio Grande Rise (RIO) and Ontong Java Plateau (OJP) and from down core sediments of varying sedimentation rates in the tropical Pacific (ME-27, MD98 2177, and MW91-9 56GGC) reveal that sediments with the greatest accumulation rates produce the least age offsets among coexisting species. Age offsets among coexisting foraminifers are about 3500 years on RIO, and 1000 years on OJP. Two core tops from RIO yield an age of the Last Glacial Maximum possibly due to mass displacement of younger sediments downslope. Foraminifer age increases with increasing dissolution and there is a consistent pattern of older foraminifer fragments coexisting with younger whole shells of the same species. The only exception is sediments which have experienced high dissolution where fragments are younger than whole shells. The age offset between fragments of G. menardii and its coexisting whole shells does not exceed the age offset among other coexisting foraminifer species in the same core tops.

  13. Effects of the global changes on the aquatic ecosystems in West Europe - role of the plankton communities

    International Nuclear Information System (INIS)

    Souissi, S.

    2007-01-01

    Examination of long-term records of aquatic ecosystems has provided useful information to find out their major driving forces. Understanding the impact of climate change on these ecosystems, the management of their resources and the extrapolation between sites are the main scopes of actual and emerging studies. Such goals can be achieved by inter-site and inter-ecosystem comparisons. This approach was undertaken during our project which has the originality to tackle with marine and freshwater ecosystems. It allowed us to compile and validate several multi-decadal time series of planktonic and other physical driving forces at local and regional scales. Then, the same methodology based on the analysis of the variability of climate indices and biological data across several spatial scales was used. The different ecosystems analyzed here showed clear response to the North Atlantic climate variability. Although the local differences abrupt changes in community composition occurred in all ecosystems in the middle of the years 80. During this period there was also a major shift in climatic conditions during winter and early spring, suggesting an impact of climatic factors. Phenological changes were also observed in plankton communities in all sites. The consequences of the modifications of plankton dynamics on higher trophic levels were also showed. Fluctuations in plankton have resulted in long-term changes in cod recruitment in the North Sea (bottom-up control). On the other hand, both climate change and the improvement of trophic status in Geneva Lake favored the outbreak of whitefish during the years 90. Lower larval mortality and better recruitment are supposed to be linked to faster growth associated with warmer temperatures and better food conditions induced by better temporal overlap between larvae hatching and zooplankton development. (author)

  14. Planktonic food web structure at a coastal time-series site: I. Partitioning of microbial abundances and carbon biomass

    Science.gov (United States)

    Caron, David A.; Connell, Paige E.; Schaffner, Rebecca A.; Schnetzer, Astrid; Fuhrman, Jed A.; Countway, Peter D.; Kim, Diane Y.

    2017-03-01

    Biogeochemistry in marine plankton communities is strongly influenced by the activities of microbial species. Understanding the composition and dynamics of these assemblages is essential for modeling emergent community-level processes, yet few studies have examined all of the biological assemblages present in the plankton, and benchmark data of this sort from time-series studies are rare. Abundance and biomass of the entire microbial assemblage and mesozooplankton (>200 μm) were determined vertically, monthly and seasonally over a 3-year period at a coastal time-series station in the San Pedro Basin off the southwestern coast of the USA. All compartments of the planktonic community were enumerated (viruses in the femtoplankton size range [0.02-0.2 μm], bacteria + archaea and cyanobacteria in the picoplankton size range [0.2-2.0 μm], phototrophic and heterotrophic protists in the nanoplanktonic [2-20 μm] and microplanktonic [20-200 μm] size ranges, and mesozooplankton [>200 μm]. Carbon biomass of each category was estimated using standard conversion factors. Plankton abundances varied over seven orders of magnitude across all categories, and total carbon biomass averaged approximately 60 μg C l-1 in surface waters of the 890 m water column over the study period. Bacteria + archaea comprised the single largest component of biomass (>1/3 of the total), with the sum of phototrophic protistan biomass making up a similar proportion. Temporal variability at this subtropical station was not dramatic. Monthly depth-specific and depth-integrated biomass varied 2-fold at the station, while seasonal variances were generally web structure and function at this coastal observatory.

  15. Increasing Water Temperature Triggers Dominance of Small Freshwater Plankton.

    Science.gov (United States)

    Rasconi, Serena; Gall, Andrea; Winter, Katharina; Kainz, Martin J

    2015-01-01

    Climate change scenarios predict that lake water temperatures will increase up to 4°C and rainfall events will become more intense and frequent by the end of this century. Concurrently, supply of humic substances from terrestrial runoff is expected to increase, resulting in darker watercolor ("brownification") of aquatic ecosystems. Using a multi-seasonal, low trophic state mesocosm experiment, we investigated how higher water temperature and brownification affect plankton community composition, phenology, and functioning. We tested the hypothesis that higher water temperature (+3°C) and brownification will, a) cause plankton community composition to shift toward small sized phytoplankton and cyanobacteria, and, b) extend the length of the growing season entailing higher phytoplankton production later in the season. We demonstrate that the 3°C increase of water temperature favored the growth of heterotrophic bacteria and small sized autotrophic picophytoplankton cells with significantly higher primary production during warmer fall periods. However, 3X darker water (effect of brownification) caused no significant changes in the plankton community composition or functioning relative to control conditions. Our findings reveal that increased temperature change plankton community structure by favoring smaller sized species proliferation (autotrophic phytoplankton and small size cladocerans), and increase primary productivity and community turnover. Finally, results of this multi-seasonal experiment suggest that warming by 3°C in aquatic ecosystems of low trophic state may cause planktonic food web functioning to become more dominated by fast growing, r-trait species (i.e., small sizes and rapid development).

  16. Plankton of Southern Chilean fjords: trends and linkages

    Directory of Open Access Journals (Sweden)

    Tarcisio Antezana

    1999-12-01

    Full Text Available The present paper compiles and reviews past and recent results from Magellan and Fuegian fjords for an overview of the planktonic assemblage there. It first examines linkages to local, adjacent and remote environments. The plankton assemblage presents deviations from the biota of the Magellan biogeographic Province, where the occasional presence of Antarctic species is related to oceanographic phenomena at the Polar Front. Complex bathymetric and hydrographic features within the fjords suggest that the plankton is rather isolated. Adaptations and constraints for population survival, and the role of diel migrators and gregarious zooplankters with regard to bentho-pelagic coupling are discussed. Results on seasonal differences in the plankton of the largest and most isolated basin of the Strait of Magellan are compiled. In spring the plankton was dominated by large diatoms suggesting a short food chain where most of the phytoplankton bloom goes to the bottom, to the meroplankton and to a few dominant holoplankters. In summer, the phytoplankton was dominated by pico- and nanophytoplankton suggesting a more complex food web mediated by a bacterial loop. High abundance of holo- and meroplanktonic larvae coincided with spring blooming conditions.

  17. The biomass of the deep-sea benthopelagic plankton

    Science.gov (United States)

    Wishner, K. F.

    1980-04-01

    Deep-sea benthopelagic plankton samples were collected with a specially designed opening-closing net system 10 to 100 m above the bottom in five different oceanic regions at depths from 1000 to 4700 m. Benthopelagic plankton biomasses decrease exponentially with depth. At 1000 m the biomass is about 1% that of the surface zooplankton, at 5000 m about 0.1%. Effects of differences in surface primary productivity on deep-sea plankton biomass are much less than the effect of depth and are detectable only in a few comparisons of extreme oceanic regions. The biomass at 10 m above the bottom is greater than that at 100 m above the bottom (in a three-sample comparison), which could be a consequence of an enriched near-bottom environment. The deep-sea plankton biomass in the Red Sea is anomalously low. This may be due to increased decomposition rates in the warm (22°C) deep Red Sea water, which prevent much detritus from reaching the deep sea. A model of organic carbon utilization in the benthic boundary layer (bottom 100 m), incorporating results from deep-sea sediment trap and respiration studies, indicates that the benthopelagic plankton use only a small amount of the organic carbon flux. A large fraction of the flux is unaccounted for by present estimates of benthic and benthopelagic respiration.

  18. Modelling of the impact of the Rhone River N:P ratios over the NW Mediterranean planktonic food web

    Science.gov (United States)

    Alekseenko, Elena; Baklouti, Melika; Carlotti, François

    2016-04-01

    their growth and ultimately enhances our understanding of the functioning of this planktonic food-web. The present work consisted in running two different scenarios (low and high NO3:PO4 in the Rhone River). The lower ratio is the one presently found in the Rhône river outputs while the higher ratio is twice the lower one.The study focused on a one-year period (2010) since the model outputs during this period have already been partially validated (Alekseenko et al., 2014). At this stage, we first explore the spatial and temporal dynamics of the carbon stocks, in living and non-living compartments as well as related carbon fluxes. Results showed that, after one year of simulation, the change in NO3:PO4 of Rhone River mostly impacts organisms in the shelf zone of GoL, and especially the lowest trophic levels during the spring phytoplankton bloom. The increase in NO3:PO4 decreases primary production and bacterial production rates, thereby decreasing food availability for zooplankton which population growth decreases. During the spring phytoplankton bloom period, the decrease in Chl-a induced by the high NO3:PO4 Rhone ratio has an order of value comparable to the Chl-a mean level observed in the GoL. In the case of the scenario with high NO3:PO4 ratio, bacterial production increases after the spring bloom, what, in turn, increases the development of ciliates. The impact of NO3:PO4 scenarios on the mesozooplankton and jellyfish compartments considered in the model is overall low after a one-year simulation, but, probably due to their longer life cycle comparing to smaller organisms, this should be investigated at longer time scales. Acknowledgements The present research is a contribution to the Labex OT-Med (n_ ANR-11-LABX-0061) funded by the French Government «Investissements d'Avenir» program of the French National Research Agency (ANR) through the A*MIDEX project (n_ ANR-11 IDEX-0001-02). The work is also partially supported by the grant of Russian Foundation for Basic

  19. Comparative Salt Stress Study on Intracellular Ion Concentration in Marine and Salt-adapted Freshwater Strains of Microalgae

    Directory of Open Access Journals (Sweden)

    Ahmad Farhad TALEBI

    2013-08-01

    Full Text Available Salinity imposes significant stresses in various living organisms including microalgae. High extracellular concentration of Na+ directly influences ionic balance inside the cell and subsequently the cellular activities. In the present study, the effect of such stress on growth and intracellular ions concentration (IIC of Dunaliella salina and Chlorella Spp. was investigated. IIC was analyzed using Ion chromatography technique. D. salina showed the highest degree of resistance to increase in salinity as little changes occurred both in IIC and in growth parameters. D. salina could maintain the balance of K+ inside the cell and eject the excess Na+ even at NaCl concentrations above 1M. Moreover, D. salina accumulated β-carotene in order to protect its photosynthetic apparatus. Among Chlorella species, C. vulgaris showed signs of adaptation to high content of salinity, though it is a fresh water species by nature. Moreover, the response shown by C. vulgaris to rise in salinity was even stronger than that of C. salina, which is presumably a salt-water resistant species. In fact, C. vulgaris could maintain intracellular K+ better than C. salina in response to increasing salinity, and as a result, it could survive at NaCl concentrations as high as 0.75 M. Marine strains such as D. salina well cope with the fluctuations in salinity through the existing adaptation mechanisms i.e. maintaining the K+/N+ balance inside the cell, K+ accumulation and Na+ ejection, accumulation of photosynthetic pigments like β-carotene.

  20. Wave of chaos in a diffusive system: Generating realistic patterns of patchiness in plankton-fish dynamics

    International Nuclear Information System (INIS)

    Upadhyay, Ranjit Kumar; Kumari, Nitu; Rai, Vikas

    2009-01-01

    We show that wave of chaos (WOC) can generate two-dimensional time-independent spatial patterns which can be a potential candidate for understanding planktonic patchiness observed in marine environments. These spatio-temporal patterns were obtained in computer simulations of a minimal model of phytoplankton-zooplankton dynamics driven by forces of diffusion. We also attempt to figure out the average lifetimes of these non-linear non-equilibrium patterns. These spatial patterns serve as a realistic model for patchiness found in aquatic systems (e.g., marine and oceanic). Additionally, spatio-temporal chaos produced by bi-directional WOCs is robust to changes in key parameters of the system; e.g., intra-specific competition among individuals of phytoplankton and the rate of fish predation. The ideas contained in the present paper may find applications in diverse fields of human endeavor.

  1. Ecology and distribution of recent planktonic foraminifera in eastern part of Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Kutty, M.K.

    Thirty species of living planktonic foraminifera have been studied from 97 plankton tows collected from the eastern Arabian Sea with an accent on their ecological and distributional aspects. Species density is higher with less dominance in the deep...

  2. Comparative performances of eggs and embryos of sea urchin (Paracentrotus lividus) in toxicity bioassays used for assessment of marine sediment quality.

    Science.gov (United States)

    Khosrovyan, A; Rodríguez-Romero, A; Salamanca, M J; Del Valls, T A; Riba, I; Serrano, F

    2013-05-15

    The potential toxicity of sediments from various ports was assessed by means of two different liquid-phase toxicity bioassays (acute and chronic) with embryos and eggs of sea urchin Paracentrotus lividus. Performances of embryos and eggs of P. lividus in these bioassays were compared for their interchangeable applicability in integrated sediment quality assessment. The obtained endpoints (percentages of normally developed plutei and fertilized eggs) were linked to physical and chemical properties of sediments and demonstrated dependence on sediment contamination. The endpoints in the two bioassays were strongly correlated and generally exhibited similar tendency throughout the samples. Therein, embryos demonstrated higher sensitivity to elutriate exposure, compared to eggs. It was concluded that these tests could be used interchangeably for testing toxicity of marine sediments. Preferential use of any of the bioassays can be determined by the discriminatory capacity of the test or vulnerability consideration of the test subject to the surrounding conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Determining Microeukaryotic Plankton Community around Xiamen Island, Southeast China, Using Illumina MiSeq and PCR-DGGE Techniques.

    Directory of Open Access Journals (Sweden)

    Lingyu Yu

    Full Text Available Microeukaryotic plankton are important components of aquatic environments and play key roles in marine microbial food webs; however, little is known about their genetic diversity in subtropical offshore areas. Here we examined the community composition and genetic diversity of the microeukaryotic plankton in Xiamen offshore water by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis, clone-based sequencing and Illumina based sequencing. The Illumina MiSeq sequencing revealed a much (approximately two orders of magnitude higher species richness of the microeukaryotic community than DGGE, but there were no significant difference in species richness and diversity among the northern, eastern, southern or western stations based on both methods. In this study, Copepoda, Ciliophora, Chlorophyta, Dinophyceae, Cryptophyta and Bacillariophyta (diatoms were the dominant groups even though diatoms were not detected by DGGE. Our Illumina based results indicated that two northern communities (sites N2 and N3 were significantly different from others in having more protozoa and fewer diatoms. Redundancy analysis (RDA showed that both temperature and salinity were the significant environmental factors influencing dominant species communities, whereas the full microeukaryotic community appeared to be affected by a complex of environmental factors. Our results suggested that extensive sampling combined with more deep sequencing are needed to obtain the complete diversity of the microeukaryotic community, and different diversity patterns for both abundant and rare taxa may be important in evaluating the marine ecosystem health.

  4. ASSESSING THE STATE OF THE PELAGIC HABITAT: A CASE STUDY OF PLANKTON AND ITS ENVIRONMENT IN THE WESTERN IRISH SEA

    Directory of Open Access Journals (Sweden)

    Cordula Scherer

    2016-11-01

    Full Text Available Much work had been undertaken on tracking change in the condition of marine pelagic ecosystems and on identifying regime shifts. However, it is also necessary to relate change to states of good ecosystem health or what the European Marine Strategy Framework Directive (MSFD calls 'Good Environmental Status' (GES. Drawing on existing scientific and legislative principles, including those of OSPAR's 'Strategy to Combat Eutrophication', we propose a framework for assessing the status of what the MSFD calls the 'pelagic habitat' in temperate coastal seas. The framework uses knowledge of local ecohydrodynamic conditions, especially those relating to the stratification and optical environment, to guide expectations of what would be recognised as healthy in terms of ecosystem 'organisation' and 'vigour'. We apply this framework to the seasonally stratified regime of the Western Irish Sea, drawing on published and new work on stratification, nutrient and phytoplankton seasonal cycles, zooplankton, and the implications of plankton community structure and production for higher trophic levels. We conclude that, despite human pressures including nutrient enrichment, and the food-web effects of fisheries, the pelagic ecosystem here is in GES, and hence may be used as a reference for the 'Plankton Index' method of tracking change in state space in seasonally stratified waters.

  5. Community structure and function of planktonic Crenarchaeota: changes with depth in the South China Sea.

    Science.gov (United States)

    Hu, Anyi; Jiao, Nianzhi; Zhang, Chuanlun L

    2011-10-01

    Marine Crenarchaeota represent a widespread and abundant microbial group in marine ecosystems. Here, we investigated the abundance, diversity, and distribution of planktonic Crenarchaeota in the epi-, meso-, and bathypelagic zones at three stations in the South China Sea (SCS) by analysis of crenarchaeal 16S rRNA gene, ammonia monooxygenase gene amoA involved in ammonia oxidation, and biotin carboxylase gene accA putatively involved in archaeal CO(2) fixation. Quantitative PCR analyses indicated that crenarchaeal amoA and accA gene abundances varied similarly with archaeal and crenarchaeal 16S rRNA gene abundances at all stations, except that crenarchaeal accA genes were almost absent in the epipelagic zone. Ratios of the crenarchaeal amoA gene to 16S rRNA gene abundances decreased ~2.6 times from the epi- to bathypelagic zones, whereas the ratios of crenarchaeal accA gene to marine group I crenarchaeal 16S rRNA gene or to crenarchaeal amoA gene abundances increased with depth, suggesting that the metabolism of Crenarchaeota may change from the epi- to meso- or bathypelagic zones. Denaturing gradient gel electrophoresis profiling of the 16S rRNA genes revealed depth partitioning in archaeal community structures. Clone libraries of crenarchaeal amoA and accA genes showed two clusters: the "shallow" cluster was exclusively derived from epipelagic water and the "deep" cluster was from meso- and/or bathypelagic waters, suggesting that niche partitioning may take place between the shallow and deep marine Crenarchaeota. Overall, our results show strong depth partitioning of crenarchaeal populations in the SCS and suggest a shift in their community structure and ecological function with increasing depth.

  6. Progressive changes in the Western English Channel foster a reorganization in the plankton food web

    DEFF Research Database (Denmark)

    Reygondeau, Gabriel; Molinero, J.C.; Coombs, S.

    2015-01-01

    . (2013) drive a profound restructuration of the plankton community modifying the phenology and the dominance of key planktonic groups including fish larvae. Consequently, the slow but deep modifications detected in the plankton community highlight a climate driven ecosystem shift in the Western English...

  7. Characterizing Marine Soundscapes.

    Science.gov (United States)

    Erbe, Christine; McCauley, Robert; Gavrilov, Alexander

    2016-01-01

    The study of marine soundscapes is becoming widespread and the amount of data collected is increasing rapidly. Data owners (typically academia, industry, government, and defense) are negotiating data sharing and generating potential for data syntheses, comparative studies, analyses of trends, and large-scale and long-term acoustic ecology research. A problem is the lack of standards and commonly agreed protocols for the recording of marine soundscapes, data analysis, and reporting that make a synthesis and comparison of results difficult. We provide a brief overview of the components in a marine soundscape, the hard- and software tools for recording and analyzing marine soundscapes, and common reporting formats.

  8. Marine n-3 polyunsaturated fatty acids in patients with end-stage renal failure and in subjects without kidney disease: a comparative study.

    Science.gov (United States)

    Madsen, Trine; Christensen, Jeppe H; Svensson, My; Witt, Petra M; Toft, Egon; Schmidt, Erik B

    2011-03-01

    Patients with end-stage renal disease treated with chronic hemodialysis (HD) are reported to have low levels of marine n-3 polyunsaturated fatty acids (PUFA) in plasma and cell membranes compared with healthy subjects. The aim of this study was to investigate whether n-3 PUFA levels in plasma and cells are lower in HD patients as compared with subjects without kidney disease. A comparative study was carried out. This study was carried out at the Departments of Nephrology and Cardiology, Aalborg Hospital, Aarhus University Hospital, Denmark. This study consisted of 2 study populations comprising HD patients and 5 study populations comprising subjects without kidney disease. The fatty acid distribution in plasma phospholipids and platelet phospholipids was measured using gas chromatography. Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA) levels in plasma or serum phospholipids and platelet phospholipids in HD patients were compared with n-3 PUFA levels in subjects without kidney disease. EPA and DHA were lower and AA/EPA was higher in plasma/serum phospholipids in HD patients than in subjects without kidney disease. Similarly, higher AA and AA/EPA and lower EPA and DHA levels were found in platelet phospholipids of HD patients. Adjustment for gender, age, and habitual intake of fish and fish oil supplements did not change these results. HD patients have lower n-3 PUFA levels in plasma and cells compared with subjects without kidney disease. Copyright © 2011 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  9. Holocene planktonic foraminifera from the shelf sediments off Kerala Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Twenty-two planktonic foraminifers were identified from a few samples collected aboard INS KISTNA at 9~'N and 76~'E, at 89 metres depth from the bottom sediment-water interface. A few of the more characteristic features of each are described. Some...

  10. Planktonic Biodiversity of Bhoj Wetland, Bhopal, India | Neelam ...

    African Journals Online (AJOL)

    Biodiversity found on Earth today consists of many millions of distinct biological species, which is the product of nearly 3.5 billion years of evolution. This article deals with planktonic distribution of Bhoj Wetland, Bhopal, India . Bhoj Wetland comprises of two lakes i.e. Upper and Lower lakes of Bhopal. The Upper lake is ...

  11. Plankton dynamics associated with the convergence zone of a shear ...

    African Journals Online (AJOL)

    Multiple linear regression was used to determine the relationships between water quality variables and plankton abundances. Community analysis was also run on the data in order to determine community dynamics associated with frontal system convergence and downwelling. Key words: ichthyoplankton, phytoplankton, ...

  12. The comparative effects of oil dispersants and oil/dispersant conjugates on germination of the marine macroalga Phyllospora comosa (Fucales: Phaeophyta)

    International Nuclear Information System (INIS)

    Burridge, T.R.; Shir, M.-A.

    1995-01-01

    Germination inhibition of the marine macrophyte Phyllospora comosa was utilized as a sub-lethal end-point to assess and compare the effects of four oil dispersants and dispersed diesel fuel and crude oil combinations. Inhibition of germination by the water-soluble fraction of diesel fuel increased following the addition of each of the dispersants; the nominal 48-h EC 50 concentration of diesel fuel declined from 6800 to approximately 400 μl 1 -1 nominal for each dispersed combination. This contrasted with crude oil, where the addition of two dispersants resulted in an enhanced germination rate and an increase in nominal EC 50 concentrations from 130 μl 1 -1 for the undispersed crude to 4000 and 2500 μl 1 -1 . The results indicate that, while germination inhibition of P. comosa may be enhanced by the chemical dispersal of oil response varies with type of both oil and oil dispersant. (author)

  13. Biogeochemical Indicators in High- and Low-Arctic Marine and Terrestrial Avian Community Changes: Comparative Isotopic (13C, 15N, and 34S) Studies in Alaska and Greenland

    Science.gov (United States)

    Causey, D.; Bargmann, N. A.; Burnham, K. K.; Burnham, J. L.; Padula, V. M.; Johnson, J. A.; Welker, J. M.

    2011-12-01

    Understanding the complex dynamics of environmental change in northern latitudes is of paramount importance today, given documented rapid shifts in sea ice, plant phenology, temperatures, deglaciation, and habitat fidelity. This knowledge is particularly critical for Arctic avian communities, which are integral components by which biological teleconnections are maintained between the mid and northern latitudes. Furthermore, Arctic birds are fundamental to Native subsistence lifestyles and a focus for conservation activities. Avian communities of marine and terrestrial Arctic environments represent a broad spectrum of trophic levels, from herbivores (eg., geese Chen spp.), planktivores (eg., auklets Aethia spp.), and insectivores (eg., passerines: Wheatears Oenanthe spp., Longspurs Calcarius spp.), to predators of marine invertebrates (eg., eiders Somateria spp.), nearshore and offshore fish (eg., cormorants Phalacrocorax spp, puffins Fratercula spp.), even other bird species (eg., gulls Larus spp., falcons Peregrinus spp.). This diversity of trophic interconnections is an integral factor in the dynamics of Arctic ecosystem ecology, and they are key indicators for the strength and trajectories of change. We are especially interested in their feeding ecology, using stable isotope-diet relations to examine historical diets and to predict future feeding ecology by this range of species. Since 2009, we have been studying the foodweb ecology using stable isotopes (δ13C, δ15N, δ34S) of contemporaneous coastal and marine bird communities in High Arctic (Northwest Greenland) and Low Arctic (western Aleutian Islands, AK). We are quantifying the isotopic values of blood, organ tissues, and feathers, and have carried out comparisons between native and lipid-extracted samples. Although geographically distant, these communities comprise similar taxonomic and ecological congeners, including several species common to both (eg., Common Eider, Black-legged Kittiwake, Northern

  14. Oligotrophy as a major driver of mercury bioaccumulation in medium-to high-trophic level consumers: A marine ecosystem-comparative study.

    Science.gov (United States)

    Chouvelon, Tiphaine; Cresson, Pierre; Bouchoucha, Marc; Brach-Papa, Christophe; Bustamante, Paco; Crochet, Sylvette; Marco-Miralles, Françoise; Thomas, Bastien; Knoery, Joël

    2018-02-01

    Mercury (Hg) is a global contaminant of environmental concern. Numerous factors influencing its bioaccumulation in marine organisms have already been described at both individual and species levels (e.g., size or age, habitat, trophic level). However, few studies have compared the trophic characteristics of ecosystems to explain underlying mechanisms of differences in Hg bioaccumulation and biomagnification among food webs and systems. The present study aimed at investigating the potential primary role of the trophic status of systems on Hg bioaccumulation and biomagnification in temperate marine food webs, as shown by their medium-to high-trophic level consumers. It used data from samples collected at the shelf-edge (i.e. offshore organisms) in two contrasted ecosystems: the Bay of Biscay in the North-East Atlantic Ocean and the Gulf of Lion in the North-West Mediterranean Sea. Seven species including crustaceans, sharks and teleost fish, previously analysed for their total mercury (T-Hg) concentrations and their stable carbon and nitrogen isotope compositions, were considered for a meta-analysis. In addition, methylated mercury forms (or methyl-mercury, Me-Hg) were analysed. Mediterranean organisms presented systematically lower sizes than Atlantic ones, and lower δ 13 C and δ 15 N values, the latter values especially highlighting the more oligotrophic character of Mediterranean waters. Mediterranean individuals also showed significantly higher T-Hg and Me-Hg concentrations. Conversely, Me-Hg/T-Hg ratios were higher than 85% for all species, and quite similar between systems. Finally, the biomagnification power of Hg was different between systems when considering T-Hg, but not when considering Me-Hg, and was not different between the Hg forms within a given system. Overall, the different parameters showed the crucial role of the low primary productivity and its effects rippling through the compared ecosystems in the higher Hg bioaccumulation seen in organisms

  15. Increasing Water Temperature Triggers Dominance of Small Freshwater Plankton.

    Directory of Open Access Journals (Sweden)

    Serena Rasconi

    Full Text Available Climate change scenarios predict that lake water temperatures will increase up to 4°C and rainfall events will become more intense and frequent by the end of this century. Concurrently, supply of humic substances from terrestrial runoff is expected to increase, resulting in darker watercolor ("brownification" of aquatic ecosystems. Using a multi-seasonal, low trophic state mesocosm experiment, we investigated how higher water temperature and brownification affect plankton community composition, phenology, and functioning. We tested the hypothesis that higher water temperature (+3°C and brownification will, a cause plankton community composition to shift toward small sized phytoplankton and cyanobacteria, and, b extend the length of the growing season entailing higher phytoplankton production later in the season. We demonstrate that the 3°C increase of water temperature favored the growth of heterotrophic bacteria and small sized autotrophic picophytoplankton cells with significantly higher primary production during warmer fall periods. However, 3X darker water (effect of brownification caused no significant changes in the plankton community composition or functioning relative to control conditions. Our findings reveal that increased temperature change plankton community structure by favoring smaller sized species proliferation (autotrophic phytoplankton and small size cladocerans, and increase primary productivity and community turnover. Finally, results of this multi-seasonal experiment suggest that warming by 3°C in aquatic ecosystems of low trophic state may cause planktonic food web functioning to become more dominated by fast growing, r-trait species (i.e., small sizes and rapid development.

  16. Lunar periodicity in the shell flux of planktonic foraminifera in the Gulf of Mexico

    Science.gov (United States)

    Jonkers, Lukas; Reynolds, Caitlin E.; Richey, Julie N.; Hall, Ian R.

    2015-01-01

    Synchronised reproduction offers clear benefits to planktonic foraminifera – an important group of marine calcifiers – as it increases the chances of successful gamete fusion. Such synchrony requires tuning to an internal or external clock. Evidence exists for lunar reproductive cycles in some species, but its recognition in shell flux time series has proven difficult, raising questions about reproductive strategies. Using spectral analysis of a 4-year time series (mostly at weekly resolution) from the northern Gulf of Mexico, we show that the shell flux ofGloborotalia menardii, Globigerinella siphonifera, Orbulina universa, Globigerinoides sacculifer, Globigerinoides ruber (both pink and white varieties), Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globigerinella calida and Globigerinita glutinata is characterised by lunar periodicity. However, the lunar rhythm is not present in all size fractions of each species and tends to be more dominant in the flux of larger shells, consistent with reproduction being more prevalent in larger specimens. Lunar periodicity is superimposed on longer term/seasonal changes in the shell fluxes, but accounts for a significant part of the variance in the fluxes. The amplitude of the lunar cycle increases roughly proportional with the magnitude of the flux, demonstrating that most of the population is indeed affected by lunar-phased synchronisation. In most species peak fluxes occur predominantly around, or just after, full moon. Only G. siphonifera and G. calida show a contrasting pattern with peaks concentrated around new moon. Although the exact cause of the synchronisation remains elusive, our data considerably increase the number of species for which lunar synchronised reproduction is reported and suggest that such reproductive behaviour is common in many species of planktonic foraminifera.

  17. Concentrations of plutonium and americium in plankton from the western Mediterranean Sea.

    Science.gov (United States)

    Sanchez-Cabeza, Joan-Albert; Merino, Juan; Masqué, Pere; Mitchell, Peter I; Vintró, L León; Schell, William R; Cross, Lluïsa; Calbet, Albert

    2003-07-20

    Understanding the transfer of radionuclides through the food chain leading to man and in particular, the uptake of transuranic nuclides by plankton, is basic to assess the potential radiological risk of the consumption of marine products by man. The main sources of transuranic elements in the Mediterranean Sea in the past were global fallout and the Palomares accident, although at present smaller amounts are released from nuclear establishments in the northwestern region. Plankton from the western Mediterranean Sea was collected and analyzed for plutonium and americium in order to study their biological uptake. The microplankton fractions accounted for approximately 50% of the total plutonium contents in particulate form. At Garrucha (Palomares area), microplankton showed much higher 239,240 Pu activity, indicating the contamination with plutonium from the bottom sediments. Concentration factors were within the range of the values recommended by the International Atomic Energy Agency. Continental shelf mesoplankton was observed to efficiently concentrate transuranics. In open seawaters, concentrations were much lower. We speculate that sediments might play a role in the transfer of transuranics to mesoplankton in coastal waters, although we cannot discard that the difference in species composition may also play a role. In Palomares, both 239,240 Pu and 241Am showed activities five times higher than the mean values observed in continental shelf mesoplankton. As the plutonium isotopic ratios in the contaminated sample were similar to those found in material related to the accident, the contamination was attributed to bomb debris from the Palomares accident. Concentration factors in mesoplankton were also in relatively good agreement with the ranges recommended by IAEA. In the Palomares station the highest concentration factor was observed in the sample that showed predominance of the dynoflagellate Ceratium spp. Mean values of the enrichment factors showed, on

  18. Spatiotemporal Distribution and Assemblages of Planktonic Fungi in the Coastal Waters of the Bohai Sea

    Directory of Open Access Journals (Sweden)

    Yaqiong Wang

    2018-03-01

    Full Text Available Fungi play a critical role in the nutrient cycling and ecological function in terrestrial and freshwater ecosystems. Yet, many ecological aspects of their counterparts in coastal ecosystems remain largely elusive. Using high-throughput sequencing, quantitative PCR, and environmental data analyses, we studied the spatiotemporal changes in the abundance and diversity of planktonic fungi and their abiotic and biotic interactions in the coastal waters of three transects along the Bohai Sea. A total of 4362 ITS OTUs were identified and more than 60% of which were unclassified Fungi. Of the classified OTUs three major fungal phyla, Ascomycota, Basidiomycota, and Chytridiomycota were predominant with episodic low dominance phyla Cryptomycota and Mucoromycota (Mortierellales. The estimated average Fungi-specific 18S rRNA gene qPCR abundances varied within 4.28 × 106 and 1.13 × 107copies/L with significantly (P < 0.05 different abundances among the transects suggesting potential influence of the different riverine inputs. The spatiotemporal changes in the OTU abundance of Ascomycota and Basidiomycota phyla coincided significantly (P < 0.05 with nutrients traced to riverine inputs and phytoplankton detritus. Among the eight major fungal orders, the abundance of Hypocreales varied significantly (P < 0.01 across months while Capnodiales, Pleosporales, Eurotiales, and Sporidiobolales varied significantly (P < 0.05 across transects. In addition, our results likely suggest a tripartite interaction model for the association within members of Cryptomycota (hyperparasites, Chytridiomycota (both parasites and saprotrophs, and phytoplankton in the coastal waters. The fungal network featured several hubs and keystone OTUs besides the display of cooperative and competitive relationship within OTUs. These results support the notion that planktonic fungi, hitherto mostly undescribed, play diverse ecological roles in marine habitats and further outline niche processes

  19. Limnology and plankton diversity of salt lakes from Transylvanian Basin (Romania: A review

    Directory of Open Access Journals (Sweden)

    Mircea Alexe

    2017-09-01

    Full Text Available In the present work, we review the current knowledge on genesis, limnology and biodiversity of salt lakes distributed around the inner contour of Eastern Carpathian arc (Transylvanian Basin, Central Romania. Transylvanian salt lakes formed on ancient halite (NaCl deposits following natural processes or quarrying activities.  Most of these lakes are located in eastern (Sovata area, southern (Ocna Sibiului, and western (Turda-Cojocna parts of the Transylvanian Basin, have small surfaces (0.1-4 ha, variable depths (2-100 m, are hypersaline (>10%, w/v, total salts, mainly NaCl and permanently stratified. As consequence of steady salinity/density gradient, heat entrapment below surface layer (i.e., heliothermy develops in several Transylvanian lakes. The physical and chemical water stratification is mirrored in the partition of plankton diversity. Lakes with less saline (2-10% salinity water layers appear to harbor halotolerant representatives of phyto- (e.g., marine native Picochlorum spp. and Synechococcus spp., zoo- (e.g., Moina salina, and bacterioplankton (e.g., Actinobacteria, Verrucomicobia, whereas halophilic plankton communities (e.g., green algae Dunaliella sp., brine shrimp Artemia sp., and members of Halobacteria class dominate in the oxic surface of hypersaline (>10% salinity lakes. Molecular approaches (e.g., PCR-DGGE, 16S rRNA gene-based clone libraries, and DNA metabarcoding showed that the O2-depleted bottom brines of deep meromictic Transylvanian lakes are inhabited by known extremely halophilic anaerobes (e.g. sulfate-reducing Delta-Proteobacteria, fermenting Clostridia, methanogenic and polymer-degrading archaea in addition to representatives of uncultured/unclassified prokaryotic lineages. Overall, the plankton communities thriving in saline Transylvanian lakes seem to drive full biogeochemical cycling of main elements. However, the trophic interactions (i.e., food web structure and energy flow as well as impact of human

  20. Comparative Study on Assimilating Remote Sensing High Frequency Radar Surface Currents at an Atlantic Marine Renewable Energy Test Site

    OpenAIRE

    Lei Ren; Michael Hartnett

    2017-01-01

    A variety of data assimilation approaches have been applied to enhance modelling capability and accuracy using observations from different sources. The algorithms have varying degrees of complexity of implementation, and they improve model results with varying degrees of success. Very little work has been carried out on comparing the implementation of different data assimilation algorithms using High Frequency radar (HFR) data into models of complex inshore waters strongly influenced by both ...

  1. Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar).

    Science.gov (United States)

    Lundebye, Anne-Katrine; Lock, Erik-Jan; Rasinger, Josef D; Nøstbakken, Ole Jakob; Hannisdal, Rita; Karlsbakk, Egil; Wennevik, Vidar; Madhun, Abdullah S; Madsen, Lise; Graff, Ingvild Eide; Ørnsrud, Robin

    2017-05-01

    Contaminants and fatty acid levels in farmed- versus wild Atlantic salmon have been a hot topic of debate in terms of food safety. The present study determined dioxins (polychlorinated dibenzo-p-dioxin and dibenzofuran), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), metals and fatty acids in wild and farmed Atlantic salmon. Contaminant levels of dioxins, PCBs, OCPs (DDT, dieldrin, lindane, chlordane, Mirex, and toxaphene), and mercury were higher in wild salmon than in farmed salmon, as were the concentrations of the essential elements selenium, copper, zinc and iron, and the marine omega-3 fatty acid docosahexaenoic acid (DHA). PBDE, endosulfan, pentachlorobenzene, hexachlorobenzene, cadmium and lead levels were low and comparable in both wild and farmed fish, and there was no significant difference in the marine omega-3 fatty acid eicosapentaenoic acid (EPA) concentration. The total fat content was significantly higher in farmed than wild salmon due to a higher content of both saturated and monounsaturated fatty acids, as well as a higher content of omega-6 fatty acids. The omega-3 to omega-6 fatty acid ratio was considerably lower in farmed than wild salmon due to the high level of omega-6 fatty acids. Contaminant concentrations in Atlantic salmon were well below maximum levels applicable in the European Union. Atlantic salmon, both farmed and wild, is a good source of EPA and DHA with a 200g portion per week contributing 3.2g or 2.8g respectively, being almost twice the intake considered adequate for adults by the European Food Safety Authority (i.e. 250mg/day or 1.75g/week). Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Plankton food-webs: to what extent can they be simplified?

    Directory of Open Access Journals (Sweden)

    Domenico D'Alelio

    2016-05-01

    Full Text Available Plankton is a hugely diverse community including both unicellular and multicellular organisms, whose individual dimensions span over seven orders of magnitude. Plankton is a fundamental part of biogeochemical cycles and food-webs in aquatic systems. While knowledge has progressively accumulated at the level of single species and single trophic processes, the overwhelming biological diversity of plankton interactions is insufficiently known and a coherent and unifying trophic framework is virtually lacking. We performed an extensive review of the plankton literature to provide a compilation of data suitable for implementing food-web models including plankton trophic processes at high taxonomic resolution. We identified the components of the plankton community at the Long Term Ecological Research Station MareChiara in the Gulf of Naples. These components represented the sixty-three nodes of a plankton food-web. To each node we attributed biomass and vital rates, i.e. production, consumption, assimilation rates and ratio between autotrophy and heterotrophy in mixotrophic protists. Biomasses and rates values were defined for two opposite system’s conditions; relatively eutrophic and oligotrophic states. We finally identified 817 possible trophic links within the web and provided each of them with a relative weight, in order to define a diet-matrix, valid for both trophic states, which included all consumers, fromn anoflagellates to carnivorous plankton. Vital rates for plankton resulted, as expected, very wide; this strongly contrasts with the narrow ranges considered in plankton system models implemented so far. Moreover, the amount and variety of trophic links highlighted by our review is largely excluded by state-of-the-art biogeochemical and food-web models for aquatic systems. Plankton models could potentially benefit from the integration of the trophic diversity outlined in this paper: first, by using more realistic rates; second, by better

  3. Influence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake.

    Science.gov (United States)

    Amaral, João Henrique F; Borges, Alberto V; Melack, John M; Sarmento, Hugo; Barbosa, Pedro M; Kasper, Daniele; de Melo, Michaela L; De Fex-Wolf, Daniela; da Silva, Jonismar S; Forsberg, Bruce R

    2018-07-15

    We investigated plankton metabolism and its influence on carbon dioxide (CO 2 ) dynamics in a central Amazon floodplain lake (Janauacá, 3°23' S, 60°18' W) from September 2015 to May 2016, including a period with exceptional drought. We made diel measurements of CO 2 emissions to the atmosphere with floating chambers and depth profiles of temperature and CO 2 partial pressure (pCO 2 ) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism. Overnight community respiration (CR), and gross primary production (GPP) rates were higher in clear chambers and positively correlated with chlorophyll-a (Chl-a). CO 2 air-water fluxes varied over 24-h periods with changes in thermal structure and metabolism. Most net daily CO 2 fluxes during low water and mid-rising water at the wind exposed site were into the lake as a result of high rates of photosynthesis. All other measurements indicated net daily release to the atmosphere. Average GPP rates (6.8gCm -2 d -1 ) were high compared with other studies in Amazon floodplain lakes. The growth of herbaceous plants on exposed sediment during an exceptional drought led to large carbon inputs when these areas were flooded, enhancing CR, pCO 2 , and CO 2 fluxes. During the period when the submerged herbaceous vegetation decayed phytoplankton abundance increased and photosynthetic uptake of CO 2 occurred. While planktonic metabolism was often autotrophic (GPP:CR>1), CO 2 out-gassing occurred during most periods investigated indicating other inputs of carbon such as sediments or soils and wetland plants. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Atmospheric Deposition Effects on Plankton Communities in the Eastern Mediterranean: A Mesocosm Experimental Approach

    Directory of Open Access Journals (Sweden)

    Tatiana M. Tsagaraki

    2017-07-01

    Full Text Available The effects of atmospheric deposition on plankton community structure were examined during a mesocosm experiment using water from the Cretan Sea (Eastern Mediterranean, an area with a high frequency of atmospheric aerosol deposition events. The experiment was carried out under spring-summer conditions (May 2012. The main objective was to study the changes induced from a single deposition event, on the autotrophic and heterotrophic surface microbial populations, from viruses to zooplankton. To this end, the effects of Saharan dust addition were compared to the effects of mixed aerosol deposition on the plankton community over 9 days. The effects of the dust addition seemed to propagate throughout the food-web, with changes observed in nearly all of the measured parameters up to copepods. The dust input stimulated increased productivity, both bacterial and primary. Picoplankton, both autotrophic and heterotrophic capitalized on the changes in nutrient availability and microzooplankton abundance also increased due to increased availability of prey. Five days after the simulated deposition, copepods also responded, with an increase in egg production. The results suggest that nutrients were transported up the food web through autotrophs, which were favored by the Nitrogen supplied through both treatments. Although, the effects of individual events are generally short lived, increased deposition frequency and magnitude of events is expected in the area, due to predicted reduction in rainfall and increase in temperature, which can lead to more persistent changes in plankton community structure. Here we demonstrate how a single dust deposition event leads to enhancement of phytoplankton and microzooplankton and can eventually, through copepods, transport more nutrients up the food web in the Eastern Mediterranean Sea.

  5. Comparative Study on Assimilating Remote Sensing High Frequency Radar Surface Currents at an Atlantic Marine Renewable Energy Test Site

    Directory of Open Access Journals (Sweden)

    Lei Ren

    2017-12-01

    Full Text Available A variety of data assimilation approaches have been applied to enhance modelling capability and accuracy using observations from different sources. The algorithms have varying degrees of complexity of implementation, and they improve model results with varying degrees of success. Very little work has been carried out on comparing the implementation of different data assimilation algorithms using High Frequency radar (HFR data into models of complex inshore waters strongly influenced by both tides and wind dynamics, such as Galway Bay. This research entailed implementing four different data assimilation algorithms: Direct Insertion (DI, Optimal Interpolation (OI, Nudging and indirect data assimilation via correcting model forcing into a three-dimensional hydrodynamic model and carrying out detailed comparisons of model performances. This work will allow researchers to directly compare four of the most common data assimilation algorithms being used in operational coastal hydrodynamics. The suitability of practical data assimilation algorithms for hindcasting and forecasting in shallow coastal waters subjected to alternate wetting and drying using data collected from radars was assessed. Results indicated that a forecasting system of surface currents based on the three-dimensional model EFDC (Environmental Fluid Dynamics Code and the HFR data using a Nudging or DI algorithm was considered the most appropriate for Galway Bay. The largest averaged Data Assimilation Skill Score (DASS over the ≥6 h forecasting period from the best model NDA attained 26% and 31% for east–west and north–south surface velocity components respectively. Because of its ease of implementation and its accuracy, this data assimilation system can provide timely and useful information for various practical coastal hindcast and forecast operations.

  6. Italy. Report 2 [Marine Radioecology. Current Research and Future Scope

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, B. [Istituto di Zoologia, Universita-Parma (Italy)

    1967-03-15

    Present research programme (long-term): Radionuclides in plankton an marine sediments. Ecology of Anvantheria as Sr ''scanengers''. General distribution of radionuclides in marine environment Systematics and ecology of Avantharia, studied in different seas as a biological problem. Content of {sup 90}Sr in plankton in relation to the presence or absence of Avantharia Radiochemistry of sea sediments (littoral); sedimentological and petrographical researches for stratigraphic purposes. Fall-out and wastes radionuclides absorbed by sediments. Correlation between Acantharia and concentration factor for {sup 90}Sr. Stratigraphy of fall-out radionuclides in sea sediments. Biological researches on Acantharia rearing for turnover studies in vitro. Stratigraphical researches on recent coastal sediments for geochronological problems by means of fall-out radionuclides.

  7. Italy. Report 2 [Marine Radioecology. Current Research and Future Scope

    International Nuclear Information System (INIS)

    Schreiber, B.

    1967-01-01

    Present research programme (long-term): Radionuclides in plankton an marine sediments. Ecology of Anvantheria as Sr ''scanengers''. General distribution of radionuclides in marine environment Systematics and ecology of Avantharia, studied in different seas as a biological problem. Content of 90 Sr in plankton in relation to the presence or absence of Avantharia Radiochemistry of sea sediments (littoral); sedimentological and petrographical researches for stratigraphic purposes. Fall-out and wastes radionuclides absorbed by sediments. Correlation between Acantharia and concentration factor for 90 Sr. Stratigraphy of fall-out radionuclides in sea sediments. Biological researches on Acantharia rearing for turnover studies in vitro. Stratigraphical researches on recent coastal sediments for geochronological problems by means of fall-out radionuclides

  8. Comparative cradle-to-grave life cycle assessment of biogas production from marine algae and cattle manure biorefineries.

    Science.gov (United States)

    Giwa, Adewale

    2017-11-01

    The environmental impacts resulting from the cradle-to-grave life cycles of Enteromorpha prolifera macroalgae and cattle manure biorefineries are assessed and compared. Sensitivity analysis is carried out to evaluate the response of the impacts to changes in biogas application by using Simapro 7.3.3. Three scenarios are considered in the biorefineries. In the first and second scenarios, the biogas produced is considered to be used for electricity production and transportation, respectively. In the third scenario, the biogas is considered to be recycled back to the systems. Process energy requirements and transportation of inputs contribute the largest share of the overall impacts. The cattle manure biorefinery is slightly more eco-friendly than the macroalgae biorefinery in Scenarios 1 and 2 because it requires more eco-friendly inputs. However, the macroalgae biorefinery becomes more eco-friendly than the cattle manure biorefinery in Scenario 3 because macroalgae require less energy and water for biogas production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Marine ecology

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Studies on marine ecology included marine pollution; distribution patterns of Pu and Am in the marine waters, sediments, and organisms of Bikini Atoll and the influence of physical, chemical, and biological factors on their movements through marine biogeochemical systems; transfer and dispersion of organic pollutants from an oil refinery through coastal waters; transfer of particulate pollutants, including sediments dispersed during construction of offshore power plants; and raft culture of the mangrove oysters

  10. The role of marine zooplankton in the vertical oceanic transport of alpha-emitting nuclides

    International Nuclear Information System (INIS)

    Cherry, R.D.; Heyraud, M.; Higgo, J.J.W.; Fowler, S.W.; LaRosa, J.

    1976-01-01

    This project aims at studying, in quantitative detail, the role played by marine plankton in the vertical oceanic transport of alpha-emitting nuclides. The common Mediterranean euphausiid, Meganyotiphanes norvegica, for which the necessary quantitative biological data are available as a result of previous work in the Monaco Laboratory, has been selected as the typical macrozooplanktonic species which is the focus of this work

  11. Validation and application of fossil DNA as a recorder of past marine ecosystems and environmental conditions

    NARCIS (Netherlands)

    Boere, A.C.

    2010-01-01

    The majority of planktonic species, including those that are informative in the reconstructions of past marine environmental conditions, do not produce diagnostic features (e.g., cysts, spores, or lipid biomarkers) and would therefore escape identification from the fossil record using traditional

  12. Genes and Structural Proteins of the Phage Syn5 of the Marine Cyanobacteria Synechococcus

    Science.gov (United States)

    2005-09-01

    Morgan et al., 2002; van de Putte et al., 1980). Inversion of the segment is controlled by a phage encoded invertase , expressed by the gene gin, which...growth of marine planktonic cyanobacteria. Methods in Enzymology , 167, 100-105. 170 Weigele, P.R., Scanlon, E. and King, J. (2003) Homotrimeric, beta

  13. Marine Biology: Ecology of the Sea. A Zephyr Learning Packet. Revised.

    Science.gov (United States)

    Tanner, Joey

    From the smallest plankton to the most massive whales, marine biology is the study of the flora and fauna, the living creatures of the ocean. This Zephyr self-directed study unit was developed to bridge the gap between students as passive learners to students as active participants. Originally developed for gifted students, these units emphasize…

  14. Marine pollution

    International Nuclear Information System (INIS)

    Albaiges, J.

    1989-01-01

    This book covers the following topics: Transport of marine pollutants; Transformation of pollutants in the marine environment; Biological effects of marine pollutants; Sources and transport of oil pollutants in the Persian Gulf; Trace metals and hydrocarbons in Syrian coastal waters; and Techniques for analysis of trace pollutants

  15. Marine sampling in Malaysia coastal area: the challenge, problems and solution

    International Nuclear Information System (INIS)

    Norfaizal Mohamed; Khairul Nizam Razali; Mohd Rafaie Mohd Murtadza; Muhammad Amin Abdul Ghani; Zaharudin Ahmad; Abdul Kadir Ishak

    2005-01-01

    Malaysia Marine Radioactivity Database Development Project is one of the five research contracts that was signed between MINT and AELB. Three marine sampling expeditions had been carried out using K.L. PAUS vessel owned by Malaysian Fisheries Institute, Chendering, Terengganu. The first marine sampling expedition was taken place at East Coast Peninsular Malaysia waters on August 2003, followed on February 2004 at West Coast Peninsular Malaysia waters, and lastly at Sarawak-Sabah waters on July 2004. Many challenges and problems were faced when collecting sediment, water, biota and plankton sample during this marine sampling. (Author)

  16. Plankton networks driving carbon export in the oligotrophic ocean

    Science.gov (United States)

    Larhlimi, Abdelhalim; Roux, Simon; Darzi, Youssef; Audic, Stephane; Berline, Léo; Brum, Jennifer; Coelho, Luis Pedro; Espinoza, Julio Cesar Ignacio; Malviya, Shruti; Sunagawa, Shinichi; Dimier, Céline; Kandels-Lewis, Stefanie; Picheral, Marc; Poulain, Julie; Searson, Sarah; Stemmann, Lars; Not, Fabrice; Hingamp, Pascal; Speich, Sabrina; Follows, Mick; Karp-Boss, Lee; Boss, Emmanuel; Ogata, Hiroyuki; Pesant, Stephane; Weissenbach, Jean; Wincker, Patrick; Acinas, Silvia G.; Bork, Peer; de Vargas, Colomban; Iudicone, Daniele; Sullivan, Matthew B.; Raes, Jeroen; Karsenti, Eric; Bowler, Chris; Gorsky, Gabriel

    2015-01-01

    The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterised. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria, alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of just a few bacterial and viral genes can predict most of the variability in carbon export in these regions. PMID:26863193

  17. Plankton networks driving carbon export in the oligotrophic ocean

    Science.gov (United States)

    2016-04-01

    The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterized. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria and alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of a few bacterial and viral genes can predict a significant fraction of the variability in carbon export in these regions.

  18. High motility reduces grazing mortality of planktonic bacteria

    DEFF Research Database (Denmark)

    Matz, Carsten; Jurgens, K.

    2005-01-01

    We tested the impact of bacterial swimming speed on the survival of planktonic bacteria in the presence of protozoan grazers. Grazing experiments with three common bacterivorous nanoflagellates revealed low clearance rates for highly motile bacteria. High-resolution video microscopy demonstrated...... size revealed highest grazing losses for moderately motile bacteria with a cell size between 0.2 and 0.4 mum(3). Grazing mortality was lowest for cells of >0.5 mum(3) and small, highly motile bacteria. Survival efficiencies of >95% for the ultramicrobacterial isolate CP-1 (less than or equal to0.1 mum......(3), >50 mum s(-1)) illustrated the combined protective action of small cell size and high motility. Our findings suggest that motility has an important adaptive function in the survival of planktonic bacteria during protozoan grazing....

  19. Microbial extracellular polymeric substances in marine biogeochemical processes

    Digital Repository Service at National Institute of Oceanography (India)

    Bhaskar, P.V.; Bhosle, N.B.

    and are found in free dissolved form, colloids, discreet partcles like TEP and/or associated with particulate matter, including cell aggregates, detritus, biofilms, microbial mats, etc. The chemical composition of EPS is influenced by various factors... of EPS in marine waters. Hence, various aspects of EPS di- cussed hereafter indicate bacterial and/or phyto origin unless specified. Characteristics of EPS Microorganisms grow in free planktonic state16,17 or are ata- ched to surfaces (natural...

  20. Using the marine unicellular algae in biological monitoring

    OpenAIRE

    Kapkov V. I.; Shoshina E. V.; Belenikina O. A.

    2017-01-01

    The possibility of using marine unicellular algae from natural plankton community in biomonitoring of pollution by heavy metals has been investigated. Algae of different taxa from the Mediterranean Sea have been allocated to culture. In the laboratory the culture conditions – i. e. growth medium, temperature, photoperiod, level of artificial light and initial density – have been selected for every species. The impact of heavy metals (Hg, Cd, Cu, Pb) in the form of chloride salts on the growth...

  1. Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar)

    International Nuclear Information System (INIS)

    Lundebye, Anne-Katrine; Lock, Erik-Jan; Rasinger, Josef D.; Nøstbakken, Ole Jakob; Hannisdal, Rita; Karlsbakk, Egil; Wennevik, Vidar; Madhun, Abdullah S.; Madsen, Lise; Graff, Ingvild Eide; Ørnsrud, Robin

    2017-01-01

    Contaminants and fatty acid levels in farmed- versus wild Atlantic salmon have been a hot topic of debate in terms of food safety. The present study determined dioxins (polychlorinated dibenzo-p-dioxin and dibenzofuran), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), metals and fatty acids in wild and farmed Atlantic salmon. Contaminant levels of dioxins, PCBs, OCPs (DDT, dieldrin, lindane, chlordane, Mirex, and toxaphene), and mercury were higher in wild salmon than in farmed salmon, as were the concentrations of the essential elements selenium, copper, zinc and iron, and the marine omega-3 fatty acid docosahexaenoic acid (DHA). PBDE, endosulfan, pentachlorobenzene, hexachlorobenzene, cadmium and lead levels were low and comparable in both wild and farmed fish, and there was no significant difference in the marine omega-3 fatty acid eicosapentaenoic acid (EPA) concentration. The total fat content was significantly higher in farmed than wild salmon due to a higher content of both saturated and monounsaturated fatty acids, as well as a higher content of omega-6 fatty acids. The omega-3 to omega-6 fatty acid ratio was considerably lower in farmed than wild salmon due to the high level of omega-6 fatty acids. Contaminant concentrations in Atlantic salmon were well below maximum levels applicable in the European Union. Atlantic salmon, both farmed and wild, is a good source of EPA and DHA with a 200 g portion per week contributing 3.2 g or 2.8 g respectively, being almost twice the intake considered adequate for adults by the European Food Safety Authority (i.e. 250 mg/day or 1.75 g/week). - Highlights: • A comprehensive study of contaminants and nutrients in farmed- and wild Atlantic salmon. • Wild salmon had higher levels of persistent organic pollutants and mercury than farmed salmon. • Farmed salmon had higher levels of omega-6 fatty acids than wild salmon. • Farmed- and wild salmon had comparable

  2. Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar)

    Energy Technology Data Exchange (ETDEWEB)

    Lundebye, Anne-Katrine, E-mail: aha@nifes.no [National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, 5817 Bergen (Norway); Lock, Erik-Jan; Rasinger, Josef D.; Nøstbakken, Ole Jakob; Hannisdal, Rita [National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, 5817 Bergen (Norway); Karlsbakk, Egil; Wennevik, Vidar; Madhun, Abdullah S. [Institute of Marine Research,, P.O. Box 1870 Nordnes, 5817 Bergen (Norway); Madsen, Lise; Graff, Ingvild Eide; Ørnsrud, Robin [National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, 5817 Bergen (Norway)

    2017-05-15

    Contaminants and fatty acid levels in farmed- versus wild Atlantic salmon have been a hot topic of debate in terms of food safety. The present study determined dioxins (polychlorinated dibenzo-p-dioxin and dibenzofuran), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), metals and fatty acids in wild and farmed Atlantic salmon. Contaminant levels of dioxins, PCBs, OCPs (DDT, dieldrin, lindane, chlordane, Mirex, and toxaphene), and mercury were higher in wild salmon than in farmed salmon, as were the concentrations of the essential elements selenium, copper, zinc and iron, and the marine omega-3 fatty acid docosahexaenoic acid (DHA). PBDE, endosulfan, pentachlorobenzene, hexachlorobenzene, cadmium and lead levels were low and comparable in both wild and farmed fish, and there was no significant difference in the marine omega-3 fatty acid eicosapentaenoic acid (EPA) concentration. The total fat content was significantly higher in farmed than wild salmon due to a higher content of both saturated and monounsaturated fatty acids, as well as a higher content of omega-6 fatty acids. The omega-3 to omega-6 fatty acid ratio was considerably lower in farmed than wild salmon due to the high level of omega-6 fatty acids. Contaminant concentrations in Atlantic salmon were well below maximum levels applicable in the European Union. Atlantic salmon, both farmed and wild, is a good source of EPA and DHA with a 200 g portion per week contributing 3.2 g or 2.8 g respectively, being almost twice the intake considered adequate for adults by the European Food Safety Authority (i.e. 250 mg/day or 1.75 g/week). - Highlights: • A comprehensive study of contaminants and nutrients in farmed- and wild Atlantic salmon. • Wild salmon had higher levels of persistent organic pollutants and mercury than farmed salmon. • Farmed salmon had higher levels of omega-6 fatty acids than wild salmon. • Farmed- and wild salmon had comparable

  3. Ecosystem-based approach for the numerical modelling of {sup 137}Cs transfer to the western North Pacific plankton populations after the Fukushima nuclear power plant accident - New approach for the modelling of radiocesium in pelagic food chain in the Northwestern Pacific after the Fukushima nuclear power plant accident

    Energy Technology Data Exchange (ETDEWEB)

    Belharet, Mokrane [Institut de Radioprotection et de Surete Nucleaire, SESURE/ LERCM, 83507 La Seyne-sur-mer (France); Laboratoire d' Aerologie, 14 av Eduard Belin, 31400 Toulouse (France); Estournel, Claude [Laboratoire d' Aerologie, 14 av Eduard Belin, 31400 Toulouse (France); Charmasson, Sabine [Institut de Radioprotection et de Surete Nucleaire, SESURE/ LERCM, 83507 La Seyne-sur-mer (France)

    2014-07-01

    Huge quantities of radiocesium ({sup 134}Cs and {sup 137}Cs) were released to the coastal northwestern Pacific ocean after the Fukushima nuclear power plant accident, that occurred on 11 March 2011. The resultant radiocesium contamination was quickly transferred to marine biota resulting in elevated cesium levels measured in various organisms sampled over this area. This study aims to understand the mechanism of radiocesium behavior in the marine food chain under this non steady state situation (accident) and to estimate contamination levels in these organisms, by using a new modelling approach based on the coupling of three different models: a model of cesium dispersion in the ocean, an ecosystem model and a radioecological model. The model was run for 2 years (2011 and 2012) and was first applied to study marine plankton and planktonivorous fishes contamination. Results of spatio-temporal radiocesium activities in these different organisms, and calculated parameters like concentration ratios, biological half-lives, percentages of contamination coming from each compartment (food and water), and trophic transfer factors were compared to the observed values acquired before and after the accident (steady and non-steady states). (authors)

  4. Marine Sciences

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    PNL research in the marine sciences is focused on establishing a basic understanding of the mechanisms of stress and tolerance in marine organisms exposed to contaminants. Several environmental stressors had been investigated in earlier energy-related research. In a landmark study, for example, PNL had established that the severity of fish disease caused by the common infectious agent, Flexobacter columnaris, was seriously aggravated by thermal enhancement and certain ecological factors. Subsequent studies demonstrated that the primary immune response in fish, challenged by columnaris, could be permanently suppressed by comparatively low tritium exposures. The research has suggested that a potential exists for a significant biological impact when an aquatic stressor is added to an ambient background of other stressors, which may include heat, heavy metal ions, radiation or infectious microorganisms. More recently, PNL investigators have shown that in response to heavy metal contaminants, animals synthesize specific proteins (metallothioneins), which bind and sequester metals in the animals, thus decreasing metal mobility and effects. Companion studies with host-specific intracellular pathogens are being used to investigate the effects of heavy metals on the synthesis of immune proteins, which mitigate disease processes. The results of these studies aid in predicting the ecological effects of energy-related contaminants on valued fin and shellfish species

  5. Massive consumption of gelatinous plankton by Mediterranean apex predators.

    Directory of Open Access Journals (Sweden)

    Luis Cardona

    Full Text Available Stable isotopes of carbon and nitrogen were used to test the hypothesis that stomach content analysis has systematically overlooked the consumption of gelatinous zooplankton by pelagic mesopredators and apex predators. The results strongly supported a major role of gelatinous plankton in the diet of bluefin tuna (Thunnus thynnus, little tunny (Euthynnus alletteratus, spearfish (Tetrapturus belone and swordfish (Xiphias gladius. Loggerhead sea turtles (Caretta caretta in the oceanic stage and ocean sunfish (Mola mola also primarily relied on gelatinous zooplankton. In contrast, stable isotope ratios ruled out any relevant consumption of gelatinous plankton by bluefish (Pomatomus saltatrix, blue shark (Prionace glauca, leerfish (Lichia amia, bonito (Sarda sarda, striped dolphin (Stenella caerueloalba and loggerhead sea turtles (Caretta caretta in the neritic stage, all of which primarily relied on fish and squid. Fin whales (Balaenoptera physalus were confirmed as crustacean consumers. The ratios of stable isotopes in albacore (Thunnus alalunga, amberjack (Seriola dumerili, blue butterfish (Stromaeus fiatola, bullet tuna (Auxis rochei, dolphinfish (Coryphaena hyppurus, horse mackerel (Trachurus trachurus, mackerel (Scomber scombrus and pompano (Trachinotus ovatus were consistent with mixed diets revealed by stomach content analysis, including nekton and crustaceans, but the consumption of gelatinous plankton could not be ruled out completely. In conclusion, the jellyvorous guild in the Mediterranean integrates two specialists (ocean sunfish and loggerhead sea turtles in the oceanic stage and several opportunists (bluefin tuna, little tunny, spearfish, swordfish and, perhaps, blue butterfish, most of them with shrinking populations due to overfishing.

  6. Planktonic Subsidies to Surf-Zone and Intertidal Communities

    Science.gov (United States)

    Morgan, Steven G.; Shanks, Alan L.; MacMahan, Jamie H.; Reniers, Ad J. H. M.; Feddersen, Falk

    2018-01-01

    Plankton are transported onshore, providing subsidies of food and new recruits to surf-zone and intertidal communities. The transport of plankton to the surf zone is influenced by wind, wave, and tidal forcing, and whether they enter the surf zone depends on alongshore variation in surf-zone hydrodynamics caused by the interaction of breaking waves with coastal morphology. Areas with gently sloping shores and wide surf zones typically have orders-of-magnitude-higher concentrations of plankton in the surf zone and dense larval settlement in intertidal communities because of the presence of bathymetric rip currents, which are absent in areas with steep shores and narrow surf zones. These striking differences in subsidies have profound consequences; areas with greater subsidies support more productive surf-zone communities and possibly more productive rocky intertidal communities. Recognition of the importance of spatial subsidies for rocky community dynamics has recently advanced ecological theory, and incorporating surf-zone hydrodynamics would be an especially fruitful line of investigation.

  7. Marine genomics

    DEFF Research Database (Denmark)

    Oliveira Ribeiro, Ângela Maria; Foote, Andrew David; Kupczok, Anne

    2017-01-01

    Marine ecosystems occupy 71% of the surface of our planet, yet we know little about their diversity. Although the inventory of species is continually increasing, as registered by the Census of Marine Life program, only about 10% of the estimated two million marine species are known. This lag......-throughput sequencing approaches have been helping to improve our knowledge of marine biodiversity, from the rich microbial biota that forms the base of the tree of life to a wealth of plant and animal species. In this review, we present an overview of the applications of genomics to the study of marine life, from...

  8. COMPAR

    International Nuclear Information System (INIS)

    Kuefner, K.

    1976-01-01

    COMPAR works on FORTRAN arrays with four indices: A = A(i,j,k,l) where, for each fixed k 0 ,l 0 , only the 'plane' [A(i,j,k 0 ,l 0 ), i = 1, isub(max), j = 1, jsub(max)] is held in fast memory. Given two arrays A, B of this type COMPAR has the capability to 1) re-norm A and B ind different ways; 2) calculate the deviations epsilon defined as epsilon(i,j,k,l): =[A(i,j,k,l) - B(i,j,k,l)] / GEW(i,j,k,l) where GEW (i,j,k,l) may be chosen in three different ways; 3) calculate mean, standard deviation and maximum in the array epsilon (by several intermediate stages); 4) determine traverses in the array epsilon; 5) plot these traverses by a printer; 6) simplify plots of these traverses by the PLOTEASY-system by creating input data blocks for this system. The main application of COMPAR is given (so far) by the comparison of two- and three-dimensional multigroup neutron flux-fields. (orig.) [de

  9. First records of two planktonic Indo-Pacific diatoms: Chaetoceros bacteriastroides and C. pseudosymmetricus in the Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Marijeta Čalić

    2018-01-01

    Full Text Available Unusual occurrence of planktonic diatom species, Chaetoceros bacteriastroides and Chaetoceros pseudosymmetricus, was noticed in three different marine ecosystems of Adriatic Sea: the Krka Estuary and Telaščica Bay in the Central Adriatic, and in southern Adriatic offshore. From 2010 to 2015, these two Chaetoceros species were recorded in heterogeneous environmental conditions and in a very low abundances. Both species are regarded as very rare in world oceans, and consequently knowledge of their distribution and ecology is rather poor. Primarily described from tropical waters and showing Indo-Pacific distribution, C. bacteriastroides and C. pseudosymmetricus findings in Adriatic represent the northernmost records in world's oceans and seas. For C. pseudosymmetricus this is also the first occurrence in European seas. Areal expansion and introduction of new phytoplankton species in the Adriatic Sea might be related to different circulation regimes in the Ionian Sea and the concurrent rise in sea temperature in the Mediterranean in the last decade. Recent investigations have shown that entering currents, of either Atlantic/Western Mediterranean or Eastern Mediterranean origin, modify the composition of the plankton community in the Adriatic by bringing different newcomers.

  10. Inactivation kinetics of various chemical disinfectants on Aeromonas hydrophila planktonic cells and biofilms.

    Science.gov (United States)

    Jahid, Iqbal Kabir; Ha, Sang-Do

    2014-05-01

    The present article focuses on the inactivation kinetics of various disinfectants including ethanol, sodium hypochlorite, hydrogen peroxide, peracetic acid, and benzalkonium chloride against Aeromonas hydrophila biofilms and planktonic cells. Efficacy was determined by viable plate count and compared using a modified Weibull model. The removal of the biofilms matrix was determined by the crystal violet assay and was confirmed by field-emission scanning electron microscope. The results revealed that all the experimental data and calculated Weibull α (scale) and β (shape) parameters had a good fit, as the R(2) values were between 0.88 and 0.99. Biofilms are more resistant to disinfectants than planktonic cells. Ethanol (70%) was the most effective in killing cells in the biofilms and significantly reduced (preduction as well as the effectiveness of chemical disinfectants on biofilms. The study showed that the Weibull model could successfully be used on food and food contact surfaces to determine the exact contact time for killing biofilms-forming foodborne pathogens.

  11. Bioassessment of a Drinking Water Reservoir Using Plankton: High Throughput Sequencing vs. Traditional Morphological Method

    Directory of Open Access Journals (Sweden)

    Wanli Gao

    2018-01-01

    Full Text Available Drinking water safety is increasingly perceived as one of the top global environmental issues. Plankton has been commonly used as a bioindicator for water quality in lakes and reservoirs. Recently, DNA sequencing technology has been applied to bioassessment. In this study, we compared the effectiveness of the 16S and 18S rRNA high throughput sequencing method (HTS and the traditional optical microscopy method (TOM in the bioassessment of drinking water quality. Five stations reflecting different habitats and hydrological conditions in Danjiangkou Reservoir, one of the largest drinking water reservoirs in Asia, were sampled May 2016. Non-metric multi-dimensional scaling (NMDS analysis showed that plankton assemblages varied among the stations and the spatial patterns revealed by the two methods were consistent. The correlation between TOM and HTS in a symmetric Procrustes analysis was 0.61, revealing overall good concordance between the two methods. Procrustes analysis also showed that site-specific differences between the two methods varied among the stations. Station Heijizui (H, a site heavily influenced by two tributaries, had the largest difference while station Qushou (Q, a confluence site close to the outlet dam, had the smallest difference between the two methods. Our results show that DNA sequencing has the potential to provide consistent identification of taxa, and reliable bioassessment in a long-term biomonitoring and assessment program for drinking water reservoirs.

  12. In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces

    Science.gov (United States)

    Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

    2016-01-01

    Background The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). Material/Methods This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. Results Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. Conclusions The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect. PMID:27058704

  13. Can nearby eutrophic reservoirs sustain a differentiated biodiversity of planktonic microcrustaceans in a tropical semiarid basin?

    Science.gov (United States)

    Diniz, Leidiane P; Melo-Júnior, Mauro DE

    2017-01-01

    This paper aims to compare alpha and beta diversities of planktonic microcrustaceans from three reservoirs located nearby in a tropical semiarid basin. Our hypothesis was that alpha and beta diversities of the community are different, although the ecosystems are located close to each other. We carried out two sampling campaigns: dry and rainy seasons. The sampling of microcrustaceans and environmental variables (dissolved oxygen, chlorophyll a and nutrient) was performed at twelve stations and were distributed throughout the three zones (river, transition, and lacustrine), using a plankton net (45 µm). The reservoirs showed different uses and types of nitrogen predominance: Cachoeira (supply/nitrate), Borborema (sewage/ammonia) and Saco (aquaculture/ammonia). Seventeen species were recorded whose richness was assessed as particularly specific to each one of the studied reservoirs. Seasonally, both reservoirs with high anthropogenic alteration showed greater richness in the dry season. The three reservoirs located in a same basin showed different richness and composition, but the diversity did not differ between the zones of the reservoirs. Although communities are close to each other, their composition and richness were found to be distinct for each reservoir. This may be in response to the peculiar particularities, such as nitrogen sources and the different uses.

  14. Can nearby eutrophic reservoirs sustain a differentiated biodiversity of planktonic microcrustaceans in a tropical semiarid basin?

    Directory of Open Access Journals (Sweden)

    LEIDIANE P. DINIZ

    Full Text Available ABSTRACT This paper aims to compare alpha and beta diversities of planktonic microcrustaceans from three reservoirs located nearby in a tropical semiarid basin. Our hypothesis was that alpha and beta diversities of the community are different, although the ecosystems are located close to each other. We carried out two sampling campaigns: dry and rainy seasons. The sampling of microcrustaceans and environmental variables (dissolved oxygen, chlorophyll a and nutrient was performed at twelve stations and were distributed throughout the three zones (river, transition, and lacustrine, using a plankton net (45 µm. The reservoirs showed different uses and types of nitrogen predominance: Cachoeira (supply/nitrate, Borborema (sewage/ammonia and Saco (aquaculture/ammonia. Seventeen species were recorded whose richness was assessed as particularly specific to each one of the studied reservoirs. Seasonally, both reservoirs with high anthropogenic alteration showed greater richness in the dry season. The three reservoirs located in a same basin showed different richness and composition, but the diversity did not differ between the zones of the reservoirs. Although communities are close to each other, their composition and richness were found to be distinct for each reservoir. This may be in response to the peculiar particularities, such as nitrogen sources and the different uses.

  15. In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces.

    Science.gov (United States)

    Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

    2016-04-08

    BACKGROUND The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). MATERIAL AND METHODS This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. RESULTS Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. CONCLUSIONS The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect.

  16. Microbubble-Mediated Ultrasound Enhances the Lethal Effect of Gentamicin on Planktonic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Han-Xiao Zhu

    2014-01-01

    Full Text Available Previous research has found that low-intensity ultrasound enhanced the lethal effect of gentamicin on planktonic E. coli. We aimed to further investigate whether microbubble-mediated low-intensity ultrasound could further enhance the antimicrobial efficacy of gentamicin. The planktonic E. coli (ATCC 25922 was distributed to four different interventions: control (GCON, microbubble only (GMB, ultrasound only (GUS, and microbubble-mediated ultrasound (GMUS. Ultrasound was applied with 100 mW/cm2 (average intensity and 46.5 KHz, which presented no bactericidal activity. After 12 h, plate counting was used to estimate the number of bacteria, and bacterial micromorphology was observed with transmission electron microscope. The results showed that the viable counts of E. coli in GMUS were decreased by 1.01 to 1.42 log10 CFU/mL compared with GUS (P<0.01. The minimal inhibitory concentration (MIC of gentamicin against E. coli was 1 μg/mL in the GMUS and GUS groups, lower than that in the GCON and GMB groups (2 μg/mL. Transmission electron microscopy (TEM images exhibited more destruction and higher thickness of bacterial cell membranes in the GMUS than those in other groups. The reason might be the increased permeability of cell membranes for gentamicin caused by acoustic cavitation.

  17. Relationship between luminous fish and symbiosis. I. Comparative studies of lipopolysaccharides isolated from symbiotic luminous bacteria of the luminous marine fish, Physiculus japonicus.

    Science.gov (United States)

    Kuwae, T; Andoh, M; Fukasawa, S; Kurata, M

    1983-01-01

    In order to investigate the relationship between host and symbiosis in the luminous marine fish, Physiculus japonicus, the bacterial lipopolysaccharides (LPS) of symbiotic luminous bacteria were compared serologically and electrophoretically. Five symbiotic luminous bacteria (PJ strains) were separately isolated from five individuals of this fish species caught at three points, off the coasts of Chiba, Nakaminato, and Oharai. LPS preparations were made from these bacteria by Westphal's phenol-water method and highly purified by repeated ultracentrifugation. These LPSs contained little or no 2-keto-3-deoxyoctonate and had powerful mitogenic activity. In sodium dodecylsulfate polyacrylamide gel electrophoresis, these PJ-1 to -5 LPSs were separated by their electrophoretic patterns into three groups; the first group included PJ-1 and PJ-4, the second group PJ-2 and PJ-3, and the third group PJ-5 alone. The results agreed with those of the double immunodiffusion test; precipitin lines completely coalesced within each group but not with other groups. In immunoelectrophoresis, one precipitin line was observed between anti PJ-2 LPS serum and PJ-5 LPS but the electrophoretic mobility of PJ-5 LPS was clearly different from that of the PJ-2 LPS group. Furthermore, in a 50% inhibition test with PJ-2 LPS by the passive hemolysis system, the doses of PJ-2 LPS, PJ-3 LPS, and PJ-5 LPS required for 50% inhibition (ID50) in this system were 0.25, 0.25, and 21.6 micrograms/ml for each alkali-treated LPS, respectively, and the ID50's of both PJ-1 LPS and PJ-4 LPS were above 1,000 micrograms/ml. These results indicate that PJ-5 LPS has an antigenic determinant partially in common with LPS from the PJ-2 group but not with LPS from the PJ-1 group and that the symbiotic luminous bacterium PJ-5 is more closely related to the PJ-2 group than to the PJ-1 group. These results show that the species Physiculus japonicus is symbiotically associated with at least three immunologically different

  18. The Effects of U.S. Marine Corps Officer Graduate Education Programs on Officer Performance: A Comparative Analysis of Professional Military Education and Graduate Education

    National Research Council Canada - National Science Library

    Lianez, Raul

    2003-01-01

    ...) or Non-PME, on officer performance. The intent of the thesis is to provide empirical evidence to support or refute Marine Corps cultural perceptions that PME improves officer performance more than Non-PME graduate education...

  19. The identification of plankton, water quality, blood cell, and histology in culture pond of tilapia Oreochromis niloticus which infected by viral nervous necrosis (VNN)

    Science.gov (United States)

    Yanuhar, U.; Rahayu, D. T.; Musa, M.; Arfiati, D.

    2018-04-01

    Currently, Viral Nervous Necrotic (VNN) is not only attacking the marine fish but also the freshwater fish like tilapia (Oreochromis niloticus). The aims of study to identify the type of plankton, water quality status, blood cell status, also histology of VNN infected tilapia obtained in culture ponds. The methods included plankton identification and water quality analysis from the infected fish pond in the Krakal, Blitar. The quality of blood cells and the histology of tilapia infected by VNN observed using a microscope with Hematoxylin-Eosin staining. The result show plankton in a fish pond of infected tilapia includes 3 divisions: Chlorophyta, Cyanophyta, and Bacillariophyta and 2 phyla: Arthropoda, and Rotifera. The values of erythrocyte, hematocrit, and hemoglobin were smaller than normal tilapia, however, the leukocyte and macronucleus values of VNN-infected fish were higher than normal fish. The fish histology shows the vacuolation in the brain and eyes tissue. The water quality of the culture pond have the temperature, pH, turbidity, DO, CO2, NO3, PO4, TOM in the range of 30-32°C 7.0-9.0; 25cm; 6.082–7.44mg/L 3.98–9.08mg/L 1.039–1.139 mg/L; 0.051-0.054mg/L; and 11.377-13.905mg/L, respectively. VNN causing high leukocyte and macronuclei and the damaging in brain and eyes tissue in infected tilapia.

  20. UV sensitivity of planktonic net community production in ocean surface waters

    OpenAIRE

    Regaudie de Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-01-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we tes...

  1. Ocean Acidification-Induced Restructuring of the Plankton Food Web Can Influence the Degradation of Sinking Particles

    Directory of Open Access Journals (Sweden)

    Paul Stange

    2018-04-01

    Full Text Available Ocean acidification (OA is expected to alter plankton community structure in the future ocean. This, in turn, could change the composition of sinking organic matter and the efficiency of the biological carbon pump. So far, most OA experiments involving entire plankton communities have been conducted in meso- to eutrophic environments. However, recent studies suggest that OA effects may be more pronounced during prolonged periods of nutrient limitation. In this study, we investigated how OA-induced changes in low-nutrient adapted plankton communities of the subtropical North Atlantic Ocean may affect particulate organic matter (POM standing stocks, POM fluxes, and POM stoichiometry. More specifically, we compared the elemental composition of POM suspended in the water column to the corresponding sinking material collected in sediment traps. Three weeks into the experiment, we simulated a natural upwelling event by adding nutrient-rich deep-water to all mesocosms, which induced a diatom-dominated phytoplankton bloom. Our results show that POM was more efficiently retained in the water column in the highest CO2 treatment levels (>800 μatm pCO2 subsequent to this bloom. We further observed significantly lower C:N and C:P ratios in post-bloom sedimented POM in the highest CO2 treatments, suggesting that degradation processes were less pronounced. This trend is most likely explained by differences in micro- and mesozooplankton abundance during the bloom and post-bloom phase. Overall, this study shows that OA can indirectly alter POM fluxes and stoichiometry in subtropical environments through changes in plankton community structure.

  2. Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm.

    Science.gov (United States)

    Kurzbaum, Eyal; Kirzhner, Felix; Sela, Shlomo; Zimmels, Yoram; Armon, Robert

    2010-09-01

    In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent. In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10(-9) mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10(-11)-2.04 × 10(-10) and 8.04 × 10(-11)-4.39 × 10(-10) (mg phenol/CFU/h), respectively. In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ(max) = 1.15/h, K(s) = 35.4 mg/L and K(i) = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes. Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass. Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Japan [Marine Radioecology. Current Research and Future Scope

    International Nuclear Information System (INIS)

    Saiki, M.

    1967-01-01

    Among the present research programmes: Studies on rcidiochemical analysis of sea-water and fishes; Studies on uptake of radionuclides by marine organisms; Studies on internal exposure arising from marine products; The convenient and appropriate method of analysis and determination of radioactivity in sea— water and fishes is investigated; Biological concentration of fission products and induced products in fishes and plankton arc studied from the radioecological point of view; Contribution of radionuclides in fishes and algae to those in the total Japanese diet is studied, in connection with fall-out studies

  4. The novel oral glucan synthase inhibitor SCY-078 shows in vitro activity against sessile and planktonic Candida spp.

    Science.gov (United States)

    Marcos-Zambrano, Laura Judith; Gómez-Perosanz, Marta; Escribano, Pilar; Bouza, Emilio; Guinea, Jesús

    2017-07-01

    We studied the antifungal activity of SCY-078 (an orally bioavailable 1,3-β -d- glucan synthesis inhibitor), micafungin and fluconazole against the planktonic and sessile forms of 178 Candida and non- Candida isolates causing fungaemia in patients recently admitted to a large European hospital. The in vitro activity of SCY-078, micafungin and fluconazole against the planktonic form of the isolates was assessed using EUCAST EDef 7.3 and CLSI M27-A3. Antibiofilm activity was assessed using the XTT reduction assay. SCY-078 and micafungin showed potent in vitro activity against Candida and non- Candida isolates. The in vitro activity of both drugs was similar, but SYC-078 displayed significantly lower MIC values than micafungin against Candida parapsilosis and non- Candida isolates, whereas micafungin displayed significantly lower MIC values for the remaining species ( P  Candida glabrata , in which the micafungin sessile MIC values were significantly lower ( P  Candida isolates in both sessile and planktonic forms is comparable to that of micafungin. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Variable Responses to Carbon Utilization between Planktonic and Biofilm Cells of a Human Carrier Strain of Salmonella enterica Serovar Typhi.

    Directory of Open Access Journals (Sweden)

    Kalaivani Kalai Chelvam

    Full Text Available Salmonella enterica serovar Typhi (S. Typhi is a foodborne pathogen that causes typhoid fever and infects only humans. The ability of S. Typhi to survive outside the human host remains unclear, particularly in human carrier strains. In this study, we have investigated the catabolic activity of a human carrier S. Typhi strain in both planktonic and biofilm cells using the high-throughput Biolog Phenotype MicroArray, Minimum Biofilm Eradication Concentration (MBEC biofilm inoculator (96-well peg lid and whole genome sequence data. Additional strains of S. Typhi were tested to further validate the variation of catabolism in selected carbon substrates in the different bacterial growth phases. The analyzes of the carbon utilization data indicated that planktonic cells of the carrier strain, S. Typhi CR0044 could utilize a broader range of carbon substrates compared to biofilm cells. Pyruvic acid and succinic acid which are related to energy metabolism were actively catabolised in the planktonic stage compared to biofilm stage. On the other hand, glycerol, L-fucose, L-rhamnose (carbohydrates and D-threonine (amino acid were more actively catabolised by biofilm cells compared to planktonic cells. Notably, dextrin and pectin could induce strong biofilm formation in the human carrier strain of S. Typhi. However, pectin could not induce formation of biofilm in the other S. Typhi strains. Phenome data showed the utilization of certain carbon substrates which was supported by the presence of the catabolism-associated genes in S. Typhi CR0044. In conclusion, the findings showed the differential carbon utilization between planktonic and biofilm cells of a S. Typhi human carrier strain. The differences found in the carbon utilization profiles suggested that S. Typhi uses substrates mainly found in the human biliary mucus glycoprotein, gallbladder, liver and cortex of the kidney of the human host. The observed diversity in the carbon catabolism profiles among

  6. Report on the intercomparison run: radionuclides in seawater and plankton collected outside Mururoa Atoll

    International Nuclear Information System (INIS)

    Ballestra, S.; Noshkin, V.

    1991-07-01

    This report contains a brief outline of the sampling program and a summary of all available radiological data provided by the three participants. The Direction des Centres d'Experimentations Nucleaires Laboratory (DIRCEN-CEA), Montlhery, France; The Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA; and the IAEA International Laboratory of Marine Radioactivity, (IAEA-ILMR), Principality of Monaco. The IAEA-ILMR results are complied in a separate report by Ballestra et al. (1991) that has details of the program and copies of the protocol and the ''Proces-verbal de constat'' produced by the legal representative at the end of the sampling program. A sampling program was designed to collect 3 large volume seawater and 2 plankton samples from locations near the territorial limit outside Mururoa Atoll. The different samples were to be used for a radiological intercomparison exercise. A legal representative from Papeete, Tahiti (French Polynesia) was given the task to verify the authenticity of the samples and to ensure that the protocol was followed by the participants. 4 refs, 1 fig., 3 tabs

  7. A deep-sea agglutinated foraminifer tube constructed with planktonic foraminifer shells of a single species

    Science.gov (United States)

    Pearson, Paul N.; Expedition 363 Shipboard Scientific Party, IODP

    2018-01-01

    Agglutinated foraminifera are marine protists that show apparently complex behaviour in constructing their shells, involving selecting suitable sedimentary grains from their environment, manipulating them in three dimensions, and cementing them precisely into position. Here we illustrate a striking and previously undescribed example of complex organisation in fragments of a tube-like foraminifer (questionably assigned to Rhabdammina) from 1466 m water depth on the northwest Australian margin. The tube is constructed from well-cemented siliciclastic grains which form a matrix into which hundreds of planktonic foraminifer shells are regularly spaced in apparently helical bands. These shells are of a single species, Turborotalita clarkei, which has been selected to the exclusion of all other bioclasts. The majority of shells are set horizontally in the matrix with the umbilical side upward. This mode of construction, as is the case with other agglutinated tests, seems to require either an extraordinarily selective trial-and-error process at the site of cementation or an active sensory and decision-making system within the cell.

  8. Isolation of microplastics in biota-rich seawater samples and marine organisms

    Science.gov (United States)

    Cole, Matthew; Webb, Hannah; Lindeque, Pennie K.; Fileman, Elaine S.; Halsband, Claudia; Galloway, Tamara S.

    2014-01-01

    Microplastic litter is a pervasive pollutant present in aquatic systems across the globe. A range of marine organisms have the capacity to ingest microplastics, resulting in adverse health effects. Developing methods to accurately quantify microplastics in productive marine waters, and those internalized by marine organisms, is of growing importance. Here we investigate the efficacy of using acid, alkaline and enzymatic digestion techniques in mineralizing biological material from marine surface trawls to reveal any microplastics present. Our optimized enzymatic protocol can digest >97% (by weight) of the material present in plankton-rich seawater samples without destroying any microplastic debris present. In applying the method to replicate marine samples from the western English Channel, we identified 0.27 microplastics m−3. The protocol was further used to extract microplastics ingested by marine zooplankton under laboratory conditions. Our findings illustrate that enzymatic digestion can aid the detection of microplastic debris within seawater samples and marine biota. PMID:24681661

  9. The marine bacteria Shewanella frigidimarina NCIMB400 upregulates the type VI secretion system during early biofilm formation.

    Science.gov (United States)

    Linares, Denis; Jean, Natacha; Van Overtvelt, Perrine; Ouidir, Tassadit; Hardouin, Julie; Blache, Yves; Molmeret, Maëlle

    2016-02-01

    Shewanella sp. are facultative anaerobic Gram-negative bacteria, extensively studied for their electron transfer ability. Shewanella frigidimarina has been detected and isolated from marine environments, and in particular, from biofilms. However, its ability to adhere to surfaces and form a biofilm is poorly understood. In this study, we show that the ability to adhere and to form a biofilm of S. frigidimarina NCIMB400 is significantly higher than that of Shewanella oneidensis in our conditions. We also show that this strain forms a biofilm in artificial seawater, whereas in Luria-Bertani, this capacity is reduced. To identify proteins involved in early biofilm formation, a proteomic analysis of sessile versus planktonic membrane-enriched fractions allowed the identification of several components of the same type VI secretion system gene cluster: putative Hcp1 and ImpB proteins as well as a forkhead-associated domain-containing protein. The upregulation of Hcp1 a marker of active translocation has been confirmed using quantitative reverse transcription polymerase chain reaction. Our data demonstrated the presence of a single and complete type VI secretion system in S. frigidimarina NCIMB400 genome, upregulated in sessile compared with planktonic conditions. The fact that three proteins including the secreted protein Hcp1 have been identified may suggest that this type VI secretion system is functional. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. Marine biology

    International Nuclear Information System (INIS)

    Thurman, H.V.; Webber, H.H.

    1984-01-01

    This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index

  11. KOEFISIEN SAPROBIK PLANKTON DI PERAIRAN EMBUNG UNIVERSITAS NEGERI SEMARANG

    Directory of Open Access Journals (Sweden)

    AS Awaludin

    2016-04-01

    Full Text Available Embung Universitas Negeri Semarang dibangun dengan tujuan sebagai tempat penampungan air hujan dan penyerapan air di Universitas Negeri Semarang dan mempunyai kapasitas penampungan air 5.000 m3. Keberadaan embung tersebut menciptakan suatu ekosistem baru yaitu tempat hidup ikan-ikan di dalamnya. Saprobitas perairan digunakan untuk mengetahui keadaan kualitas air yang diakibatkan adanya penambahan bahan organik dalam suatu  perairan yang biasanya indikatornya adalah jumlah dan susunan spesies dari organisme di dalam perairan tersebut. Plankton dapat digunakan sebagai bioindikator perairan karena memiliki tingkat kepekaan tinggi terhadap adanya pencemaran. Penelitian ini menggunakan rancangan eksplorasi dengan metode survai, dimana penetapan stasiun pengambilan sampel dengan purposive sampling. Penempatan stasiun didasarkan atas perkiraan beban pencemar dan aktivitas yang terdapat di sepanjang aliran dari (stasiun satu sampai sembilan, pengambilan sampel dilakukan sebanyak 3 kali dengan selang waktu 2 minggu. Data dalam penelitian ini adalah data kuantitatif berupa jumlah jenis spesies plankton yang ditemukan pada penelitian ini kemudian diinterpretasikan pada tabel hubungan antara koefisien saprobitas perairan dengan tingkat pencemaran perairan. Berdasarkan perhitungan dan analisis nilai koefisien saprobik dari stasiun satu sampai sampai sembilan didapatkan nilai koefisien saprobik plankton berkisar antara -0,4 s/d 0,9. Berdasarkan kriteria tingkat pencemaran menunjukkan bahwa Embung Universitas Negeri Semarang berada dalam kondisi tercemar ringan sampai dengan sedang.Universitas Negeri Semarang Reservoir was constructed for the purpose as rain water reservoirs and water absorption in Universitas Negeri Semarang and has a water storage capacity of 5,000 cubic meters. The existence of such ponds are creating a new ecosystem where fish live in it. Saprobic waters are used to determine the state of water quality resulting from the addition of

  12. A comparative study of microbial diversity and community structure in marine sediments using poly(A tailing and reverse transcription PCR

    Directory of Open Access Journals (Sweden)

    Tatsuhiko eHoshino

    2013-06-01

    Full Text Available To obtain a better understanding of metabolically active microbial communities, we tested a molecular ecological approach using poly(A tailing of environmental 16S rRNA, followed by full-length complementary DNA (cDNA synthesis and sequencing to eliminate potential biases caused by mismatching of PCR primer sequences. The RNA pool tested was extracted from marine sediments of the Yonaguni Knoll IV hydrothermal field in the southern Okinawa Trough. The sequences obtained using the ploy(A tailing method were compared statistically and phylogenetically with those obtained using conventional reverse transcription-polymerase chain reaction (RT-PCR with published domain-specific primers. Both methods indicated that Deltaproteobacteria are predominant in sediment (>85% of the total sequence read. The poly(A tailing method indicated that Desulfobacterales were the predominant deltaproteobacteria, while most of the sequences in libraries constructed using RT-PCR were derived from Desulfuromonadales. This discrepancy may have been due to low coverage of Desulfobacterales by the primers used. A comparison of library diversity indices indicated that the poly(A tailing method retrieves more phylogenetically diverse sequences from the environment. The four archaeal 16S rRNA sequences that were obtained using the poly(A tailing method formed deeply branching lineages that were related to Candidatus Parvarchaeum and the Ancient Archaeal Group. These results clearly demonstrate that poly(A tailing followed by cDNA sequencing is a powerful and less biased molecular ecological approach for the study of metabolically active microbial communities.

  13. A Model of the Dynamics of Plankton Patchiness

    Directory of Open Access Journals (Sweden)

    Wolfgang Ebenhöh

    1980-04-01

    Full Text Available A mathematical model of the dynamics of plankton patchiness in the intermediate scale (1 km-10 km was developed. Mechanisms that may be important in the creation and destruction of patches were selected and modelled. Such mechanisms are: horizontal turbulent diffusion, noise in the vertical turbulence, vertical migration of the zooplankton combined with a velocity profile and consumption of zooplankton by fish in schools. Patchiness is described by thc usc of the moments of density distributions, coherence lengths and correlations of phytoplankton and zooplankton. These parameters are investigated as functions of time and, also, for their dependence on the parameters of the patch creation mechanisms.

  14. How the marine biotoxins affect human health.

    Science.gov (United States)

    Morabito, Silvia; Silvestro, Serena; Faggio, Caterina

    2018-03-01

    Several marine microalgae produce dangerous toxins very damaging to human health, aquatic ecosystems and coastal resources. These Harmful Algal Blooms (HABs) in recent decades seem greatly increased regarding frequency, severity and biogeographical level, causing serious health risks as a consequence of the consumption of contaminated seafood. Toxins can cause various clinically described syndromes, characterised by a wide range of symptoms: amnesic (ASP), diarrhoetic (DSP), azaspirazid (AZP), neurotoxic (NSP) and paralytic (PSP) shellfish poisonings and ciguatera fish poisoning. The spread of HABs is probably a result of anthropogenic activities and climate change, that influence marine planktonic systems, including global warming, habitat modification, eutrophication and growth of exogenous species in response to human pressures. HABs are a worldwide matter that requests local solutions and international cooperation. This review supplies an overview of HAB phenomena, and, in particular, we describe the major consequences of HABs on human health.

  15. Efficacy of a novel antimicrobial peptide against periodontal pathogens in both planktonic and polymicrobial biofilm states.

    Science.gov (United States)

    Wang, Hong-Yan; Cheng, Jya-Wei; Yu, Hui-Yuan; Lin, Li; Chih, Ya-Han; Pan, Ya-Ping

    2015-10-01

    Streptococcus gordonii, Fusobacterium nucleatum and Porphyromonas gingivalis represent the early, middle and late colonizers of the bacterial accretion in dental plaque biofilms. These sessile communities constitute a protected mode of growth that promotes survival in a hostile environment. This study describes a novel and unrecognized role for a synthetic cationic antimicrobial peptide, Nal-P-113, which inhibits and kills periodontal bacteria in planktonic state, inhibits the formation of biofilms and eradicates polymicrobial biofilms. Nal-P-113 is also stable in saliva, serum and saline solution. At a concentration less than 320 μg/mL which is harmless to normal oral cells, Nal-P-113 can kill bacteria in planktonic state. At a concentration of antimicrobial peptide Nal-P-113 (1280 μg/mL) which only causes slight damages to normal oral cells is needed to kill bacteria in biofilm state. It is worth mentioning that this concentration of Nal-P-113 is harmless to rat oral mucosa compared to chlorhexidine. The mechanism of Nal-P-113 inhibiting and killing periodontal bacteria might rely on the abilities to permeabilize and/or to form pores within the cytoplasmic membranes, thus causes the death of bacteria. Here, we provided a novel and stable antimicrobial peptide with very low mammalian cytotoxicity, which can inhibit and kill periodontal bacteria in both planktonic and polymicrobial biofilm states. Nal-P-113 is a potent antimicrobial peptide with strong antimicrobial ability, improved deficiency compared with other antibacterial peptides, and remains stable in phosphate buffered saline, saliva, brain-heart infusion medium and bovine calf serum. Nal-P-113 exhibits a broad spectrum of bacteriocidal activity with excellent eradicating capability on oral pathogens and the respective biofilms. In this study, we used propidium iodide staining, scanning electron microscopy and transmission electron microscopy to confirm that Nal-P-113 can perforate plasmalemma thereby

  16. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ... or by any means without permission in writing from the copyright holder. ..... Journal of Chemical Engineering Research and Design 82 ... Indian Ocean Marine Science Association Technical.

  17. Marine Biomedicine

    Science.gov (United States)

    Bang, Frederik B.

    1977-01-01

    Describes early scientific research involving marine invertebrate pathologic processes that may have led to new insights into human disease. Discussed are inquiries of Metchnikoff, Loeb, and Cantacuzene (immunolgic responses in sea stars, horseshoe crabs, and marine worms, respectively). Describes current research stemming from these early…

  18. Effects of ultraviolet radiation on the lower levels of the planktonic food web in Antarctica

    International Nuclear Information System (INIS)

    Ferreyra, Gustavo A.; Schloss, Irene; Tosonotto, Gabriela; Calvino, Eduardo; Rodriguez, Silvia; Cantoni, Leonardo; Gonzalez, Oscar; Ulrich, Alejandro; Hernando, Marcelo; Hernandez, Edgardo; Oyarbide, Fabricio

    2004-01-01

    Full text: Most of the studies that investigated the effects of ultraviolet radiation (UVR, 280-400 NM) on the first levels of the marine food web used experimental approaches (in situ incubations, micro and mesocosms). However, research on the responses to UVR of the micro community in their natural environment is scarce. A time series study including most of the oceanographic parameters described as controlling bacteria and phytoplankton dynamics was carried out (PAR, tidal mixing, turbulent mixing by winds and currents, nutrient stress). In this case, however, the effects of ultraviolet A and B (UVB, 280-320 nm and UVA, 320-400 nm, respectively) were added as forcing parameters. Fieldwork was done in the vicinity of Melchior Station (64 degrees 20' S, 62 degrees 59' W, Observatory Island). It involved the automated measurement of physical variables (currents, tides and meteorological data), as well as discrete sampling of physical (salinity, temperature), chemical (macro nutrients) and biological variables (bacterial and phytoplankton abundance and production, PSI I system, photo protective compounds). Sub-surface sampling (0.5 m depth) was conducted with 5 L Niskin bottles at a fixed station (sampling every 6/12 h centered at local noon during the whole study period), and vertical profiles at 6 fixed depths (0, 5, 10, 20, 30 and 50 m) were done every four days. The whole study lasted for one month, from February 11 to March 12 2002. Average upper mixed layer (UML) was around 20 m and the depth of the euphotic zone (1% of incident radiation) for UVB and UVA was respectively 17 and 32 m, suggesting a strong influence of UVR on cells within the UML. PSII activity showed a significant inverse correlation with UVB, phased with irradiance oscillations. Bacterio plankton and phytoplankton biomass and production of both presented a similar response, but minimum values were lagged by 4-6 h from UVR maxima. Mycosporin like aminoacids (MAA's) were also phased and directly

  19. Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession: First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations.

    Directory of Open Access Journals (Sweden)

    Lennart T Bach

    Full Text Available Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2 leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes-summarized by the term ocean acidification (OA-could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (~380 μatm pCO2, whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (~760 μatm pCO2. We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a "long-term mesocosm" approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1 Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2 Plankton communities fueled by regenerated nutrients may be

  20. Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession: First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations

    Science.gov (United States)

    Taucher, Jan; Boxhammer, Tim; Ludwig, Andrea; Achterberg, Eric P.; Algueró-Muñiz, María; Anderson, Leif G.; Bellworthy, Jessica; Büdenbender, Jan; Czerny, Jan; Ericson, Ylva; Esposito, Mario; Fischer, Matthias; Haunost, Mathias; Hellemann, Dana; Horn, Henriette G.; Hornick, Thomas; Meyer, Jana; Sswat, Michael; Zark, Maren; Riebesell, Ulf

    2016-01-01

    Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2) leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes–summarized by the term ocean acidification (OA)–could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (~380 μatm pCO2), whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (~760 μatm pCO2). We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a “long-term mesocosm” approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1) Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2) Plankton communities fueled by regenerated nutrients may be more

  1. Disinfection efficiencies of sage and spearmint essential oils against planktonic and biofilm Staphylococcus aureus cells in comparison with sodium hypochlorite.

    Science.gov (United States)

    Vetas, Dimitrios; Dimitropoulou, Eleni; Mitropoulou, Gregoria; Kourkoutas, Yiannis; Giaouris, Efstathios

    2017-09-18

    biofilm communities, found here to be ca. 100 times more resistant to NaOCl compared to planktonic ones, and stress the urgent need for further research on alternative, adequate and safe disinfection strategies to control them in food processing and other environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Feeding, growth, and food conversion of the marine planktonic copepod Calanus helgolandicus

    Energy Technology Data Exchange (ETDEWEB)

    Paffenhoefer, G.A.

    1976-01-01

    Food intake, growth rate, and food conversion of nauplii, copepodids, and adult females of Calanus helgolandicus were investigated experimentally at 15/sup 0/C. The diatom Lauderia borealis and the dinoflagellates Gonyaulax polyedra, Gymnodinium splendens, and Prorocentrum micans were offered separately as food at concentrations ranging from 41 to 101 ..mu..g C liter/sup -1/. Amounts of food ingested differed with concentration and species. Daily exponential growth rates were highest for nauplii and young copepodids (k = 0.29 to 0.41) and decreased gradually with increasing age of the copepods to k = 0.02. Gross growth efficiency changed during the different juvenile life periods of the copepod with maximum values for the period CdI to CIII. Feeding on L. borealis at lower food concentrations resulted in an increase in gross growth efficiency. (auth)

  3. Distribution of planktonic foraminifera in waters of the submarine coral banks in southeast Arabian Sea during winter

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Balasubramanian, T.

    Twentyfive species of planktonic foraminifera are recorded from 36 plankton tows collected from waters of the submerged coral banks- Bassas de Pedro, Sesostris and Cora Divh-located at northern end of the Laccadive group of islands in southeastern...

  4. Daytime pelagic schooling behaviour and relationships with plankton patch distribution in the Sicily Strait (Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    B. Patti

    2011-06-01

    Full Text Available In this study, hydroacoustic data collected with a scientific echosounder working at two frequencies (38 and 120 kHz over the continental shelf off the southern Sicilian coast were used in order to investigate the relationship between fish schools and plankton patches. Specifically, image analysis algorithms were applied to raw echograms in order to detect and characterise pelagic fish schools and plankton aggregations, considered as a proxy of food availability. The relationship was first investigated using estimated total plankton biomass over the whole water column and, second, by dividing the study area into three sub-regions and further distinguishing plankton patches between the surface and the bottom. In the relatively lower plankton abundance areas of Zone 1 (northern sector of the study area, results showed an inverse relationship between the biomass (and density of fish schools and the biomass of co-occurring plankton patches located close to the bottom. Instead, over the Sicilian-Maltese shelf (Zone 3, characterised by higher plankton abundances, a direct relationship was found when using plankton data from the whole water column. The observed difference between Zones 1 and 3 is probably due to diverse dominant fish species in the two sub-regions.

  5. Antimicrobial activity of vanadium chloroperoxidase on planktonic Streptococcus mutans cells and Streptococcus mutans biofilms

    NARCIS (Netherlands)

    Hoogenkamp, M.A.; Crielaard, W.; ten Cate, J.M.; Wever, R.; Hartog, A.F.; Renirie, R.

    2009-01-01

    The aim of this study was to investigate the antimicrobial activity of vanadium chloroperoxidase (VCPO) reaction products on planktonic and biofilm cellsof Streptococcus mutans C180-2. Planktonic and biofilm cells were incubated in a buffered reaction mixture containing VCPO, halide (either chloride

  6. [Interdependence of plankton spatial distribution and plancton biomass temporal oscillations: mathematical simulation].

    Science.gov (United States)

    Medvedinskiĭ, A B; Tikhonova, I A; Li, B L; Malchow, H

    2003-01-01

    The dynamics of aquatic biological communities in a patchy environment is of great interest in respect to interrelations between phenomena at various spatial and time scales. To study the complex plankton dynamics in relation to variations of such a biologically essential parameter as the fish predation rate, we use a simple reaction-diffusion model of trophic interactions between phytoplankton, zooplankton, and fish. We suggest that plankton is distributed between two habitats one of which is fish-free due to hydrological inhomogeneity, while the other is fish-populated. We show that temporal variations in the fish predation rate do not violate the strong correspondence between the character of spatial distribution of plankton and changes of plankton biomass in time: regular temporal oscillations of plankton biomass correspond to large-scale plankton patches, while chaotic oscillations correspond to small-scale plankton patterns. As in the case of the constant fish predation rate, the chaotic plankton dynamics is characterized by coexistence of the chaotic attractor and limit cycle.

  7. Covariance among North Sea nutrient and climate drivers: consequences for plankton dynamics.

    NARCIS (Netherlands)

    McQuatters-Gollop, A.; Vermaat, J.E.

    2011-01-01

    Regime shift and principal component analysis of a spatially disaggregated database capturing time-series of climatic, nutrient and plankton variables in the North Sea revealed considerable covariance between groups of ecosystem indicators. Plankton and climate time-series span the period 1958-2003,

  8. Temporal changes in plankton of the North Sea: community shfits and environmental drivers

    NARCIS (Netherlands)

    Alvarez-Fernandez, S.; Lindeboom, H.J.; Meesters, H.W.G.

    2012-01-01

    This paper analyses long-term and seasonal changes in the North Sea plankton community during the period 1970 to 2008. Based on Continuous Plankton Recorder (CPR) data covering 38 yr, major changes in both phytoplankton and zooplankton abundance and community structure were identified. Regime

  9. Living planktonic foraminifera during the late summer monsoon period in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.; Muralinath, A.S.

    with deepening of the mixed layer, since this species preferentially dwells in nutrient-rich upwelling waters. The population density of planktonic foraminifera ranges between 31 and 185 specimens per 10@u-3@@m@u3@@. The low absolute numbers of planktonic...

  10. Unsteady motion: escape jumps in planktonic copepods, their kinematics and energetics

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Andersen, Anders Peter; Langlois, Vincent J.

    2010-01-01

    velocities in other aquatic organisms. The relative duration of the pauses between power strokes was observed to increase with organism size. We demonstrate that this is an inherent property of swimming by alternating power strokes and pauses. We finally show that the Strouhal number is in the range of peak......We describe the kinematics of escape jumps in three species of 0.3–3.0 mm-sized planktonic copepods. We find similar kinematics between species with periodically alternating power strokes and passive coasting and a resulting highly fluctuating escape velocity. By direct numerical simulations, we...... estimate the force and power output needed to accelerate and overcome drag. Both are very high compared with those of other organisms, as are the escape velocities in comparison to startle velocities of other aquatic animals. Thus, the maximum weight-specific force, which for muscle motors of other animals...

  11. A web portal for accessing, viewing and comparing in situ observations, EO products and model output data

    Science.gov (United States)

    Vines, Aleksander; Hamre, Torill; Lygre, Kjetil

    2014-05-01

    The GreenSeas project (Development of global plankton data base and model system for eco-climate early warning) aims to advance the knowledge and predictive capacities of how marine ecosystems will respond to global change. A main task has been to set up a data delivery and monitoring core service following the open and free data access policy implemented in the Global Monitoring for the Environment and Security (GMES) programme. A key feature of the system is its ability to compare data from different datasets, including an option to upload one's own netCDF files. The user can for example search in an in situ database for different variables (like temperature, salinity, different elements, light, specific plankton types or rate measurements) with different criteria (bounding box, date/time, depth, Longhurst region, cruise/transect) and compare the data with model data. The user can choose model data or Earth observation data from a list, or upload his/her own netCDF files to use in the comparison. The data can be visualized on a map, as graphs and plots (e.g. time series and property-property plots), or downloaded in various formats. The aim is to ensure open and free access to historical plankton data, new data (EO products and in situ measurements), model data (including estimates of simulation error) and biological, environmental and climatic indicators to a range of stakeholders, such as scientists, policy makers and environmental managers. We have implemented a web-based GIS(Geographical Information Systems) system and want to demonstrate the use of this. The tool is designed for a wide range of users: Novice users, who want a simple way to be able to get basic information about the current state of the marine planktonic ecosystem by utilizing predefined queries and comparisons with models. Intermediate level users who want to explore the database on their own and customize the prefedined setups. Advanced users who want to perform complex queries and

  12. Aspergillus Sydowii Marine Fungal Bloom in Australian Coastal Waters, Its Metabolites and Potential Impact on Symbiodinium Dinoflagellates

    Directory of Open Access Journals (Sweden)

    Aiko Hayashi

    2016-03-01

    Full Text Available Dust has been widely recognised as an important source of nutrients in the marine environment and as a vector for transporting pathogenic microorganisms. Disturbingly, in the wake of a dust storm event along the eastern Australian coast line in 2009, the Continuous Plankton Recorder collected masses of fungal spores and mycelia (~150,000 spores/m3 forming a floating raft that covered a coastal area equivalent to 25 times the surface of England. Cultured A. sydowii strains exhibited varying metabolite profiles, but all produced sydonic acid, a chemotaxonomic marker for A. sydowii. The Australian marine fungal strains share major metabolites and display comparable metabolic diversity to Australian terrestrial strains and to strains pathogenic to Caribbean coral. Secondary colonisation of the rafts by other fungi, including strains of Cladosporium, Penicillium and other Aspergillus species with distinct secondary metabolite profiles, was also encountered. Our bioassays revealed that the dust-derived marine fungal extracts and known A. sydowii metabolites such as sydowic acid, sydowinol and sydowinin A adversely affect photophysiological performance (Fv/Fm of the coral reef dinoflagellate endosymbiont Symbiodinium. Different Symbiodinium clades exhibited varying sensitivities, mimicking sensitivity to coral bleaching phenomena. The detection of such large amounts of A. sydowii following this dust storm event has potential implications for the health of coral environments such as the Great Barrier Reef.

  13. Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensitivity distribution.

    Science.gov (United States)

    Foekema, E M; Kaag, N H B M; Kramer, K J M; Long, K

    2015-07-15

    The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6m(3) mesocosms. Five treatment levels, ranging from 2.9 to 31μg dissolved Cu/L, were created in triplicate and maintained for 82days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9μg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7μg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD. Copyright © 2015. Published by Elsevier B.V.

  14. Ecology of planktonic foraminifera and their symbiotic algae

    International Nuclear Information System (INIS)

    Gastrich, M.D.

    1986-01-01

    Two types of symbiotic algae occurred abundantly and persistently in the cytoplasm of several species of planktonic Foraminifera over a ten year period in different tropical and subtropical areas of the North Atlantic Ocean. These planktonic Foraminifera host species consistently harbored either dinoflagellates or a newly described minute coccoid algal type. There appeared to be a specific host-symbiont relationship in these species regardless of year, season or geographic locality. The larger ovoid dinoflagellates (Pyrrhophycophyta) occur in the spinose species Globigerinoides ruber, Globigerinoides sacculifer, G. conglobatus and Orbulina universa. The smaller alga, from 1.5 to 3.5 um in diameter, occurs in one spinose species Globigerinella aequilateralis and also in the non-spinose species Globigerinita glutinata, Globoquadrina dutertrei, Globorotalia menardii, Globorotalia cristata, Globorotalia inflata, Candeina nitida, in various juvenile specimens and at all seasons except the winter months in Pulleniatina obliquiloculata and Globorotalial hirsuta. Controlled laboratory studies indicated a significant C incorporation into the host cytoplasm and inorganic calcium carbonate test of Globigerinoides ruber. During incubation for up to two hours, the 14 C uptake into the cytoplasm and test in the light was significantly greater than uptake in the dark by living specimens or by dead foraminifers. There appears to be light-enhanced uptake of 14 C into the test with dinoflagellate photosynthesis contributing to host calcification. In culture, symbiotic algae were observed to survive for the duration of the lifespan of their hosts

  15. Salinity controls on Na incorporation in Red Sea planktonic foraminifera

    Science.gov (United States)

    Mezger, E. M.; de Nooijer, L. J.; Boer, W.; Brummer, G. J. A.; Reichart, G. J.

    2016-12-01

    Whereas several well-established proxies are available for reconstructing past temperatures, salinity remains challenging to assess. Reconstructions based on the combination of (in)organic temperature proxies and foraminiferal stable oxygen isotopes result in relatively large uncertainties, which may be reduced by application of a direct salinity proxy. Cultured benthic and planktonic foraminifera showed that Na incorporation in foraminiferal shell calcite provides a potential independent proxy for salinity. Here we present the first field calibration of such a potential proxy. Living planktonic foraminiferal specimens from the Red Sea surface waters were collected and analyzed for their Na/Ca content using laser ablation quadrupole inductively coupled plasma mass spectrometry. Using the Red Sea as a natural laboratory, the calibration covers a broad range of salinities over a steep gradient within the same water mass. For both Globigerinoides ruber and Globigerinoides sacculifer calcite Na/Ca increases with salinity, albeit with a relatively large intraspecimen and interspecimen variability. The field-based calibration is similar for both species from a salinity of 36.8 up to 39.6, while values for G. sacculifer deviate from this trend in the northernmost transect. It is hypothesized that the foraminifera in the northernmost part of the Red Sea are (partly) expatriated and hence should be excluded from the Na/Ca-salinity calibration. Incorporation of Na in foraminiferal calcite therefore provides a potential proxy for salinity, although species-specific calibrations are still required and more research on the effect of temperature is needed.

  16. Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition.

    Science.gov (United States)

    Benson, Roger B J; Druckenmiller, Patrick S

    2014-02-01

    Marine and terrestrial animals show a mosaic of lineage extinctions and diversifications during the Jurassic-Cretaceous transition. However, despite its potential importance in shaping animal evolution, few palaeontological studies have focussed on this interval and the possible climate and biotic drivers of its faunal turnover. In consequence evolutionary patterns in most groups are poorly understood. We use a new, large morphological dataset to examine patterns of lineage diversity and disparity (variety of form) in the marine tetrapod clade Plesiosauria, and compare these patterns with those of other organisms. Although seven plesiosaurian lineages have been hypothesised as crossing the Jurassic-Cretaceous boundary, our most parsimonious topology suggests the number was only three. The robust recovery of a novel group including most Cretaceous plesiosauroids (Xenopsaria, new clade) is instrumental in this result. Substantial plesiosaurian turnover occurred during the Jurassic-Cretaceous boundary interval, including the loss of substantial pliosaurid, and cryptoclidid diversity and disparity, followed by the radiation of Xenopsaria during the Early Cretaceous. Possible physical drivers of this turnover include climatic fluctuations that influenced oceanic productivity and diversity: Late Jurassic climates were characterised by widespread global monsoonal conditions and increased nutrient flux into the opening Atlantic-Tethys, resulting in eutrophication and a highly productive, but taxonomically depauperate, plankton. Latest Jurassic and Early Cretaceous climates were more arid, resulting in oligotrophic ocean conditions and high taxonomic diversity of radiolarians, calcareous nannoplankton and possibly ammonoids. However, the observation of discordant extinction patterns in other marine tetrapod groups such as ichthyosaurs and marine crocodylomorphs suggests that clade-specific factors may have been more important than overarching extrinsic drivers of faunal

  17. LC-MS-MS aboard ship: tandem mass spectrometry in the search for phycotoxins and novel toxigenic plankton from the North Sea.

    Science.gov (United States)

    Krock, Bernd; Tillmann, Urban; John, Uwe; Cembella, Allan

    2008-11-01

    Phycotoxins produced by various species of toxigenic microalgae occurring in the plankton are a global threat to the security of seafood resources and the health of humans and coastal marine ecosystems. This has necessitated the development and application of advanced methods in liquid chromatography coupled to mass spectrometry (LC-MS) for monitoring of these compounds, particularly in plankton and shellfish. Most such chemical analyses are conducted in land-based laboratories on stored samples, and thus much information on the near real-time biogeographical distribution and dynamics of phycotoxins in the plankton is unavailable. To resolve this problem, we conducted ship-board analysis of a broad spectrum of phycotoxins collected directly from the water column on an oceanographic cruise along the North Sea coast of Scotland, Norway, and Denmark. We equipped the ship with a triple-quadrupole linear ion-trap hybrid LC-MS-MS system for detection and quantitative analysis of toxins, such as domoic acid, gymnodimine, spirolides, dinophysistoxins, okadaic acid, pectenotoxins, yessotoxins, and azaspiracids (AZAs). We focused particular attention on the detection of AZAs, a group of potent nitrogenous polyether toxins, because the culprit species associated with the occurrence of these toxins in shellfish has been controversial. Marine toxins were analyzed directly from size-fractionated plankton net tows (20 microm mesh size) and Niskin bottle samples from discrete depths, after rapid methanolic extraction but without any further clean-up. Almost all expected phycotoxins were detected in North Sea plankton samples, with domoic acid and 20-methylspirolide G being most abundant. Although AZA was the least abundant of these toxins, the high sensitivity of the LC-MS-MS enabled detailed quantification, indicating that the highest amounts of AZA-1 were present in the southern Skagerrak in the 3-20 microm size-fraction. The direct on-board toxin measurements enabled isolation

  18. Slope Failure Hazards at Basalt Geomorphosites: A Comparative Analysis of the Giant's Causeway World Heritage Site, UK and Penghu Marine Geopark, Taiwan.

    Science.gov (United States)

    Gruendemann, Ciaran; Chung Lin, Jiun; Smith, Bernard

    2010-05-01

    Columnar basalt landscapes hold a fascination that transcends geographical and cultural boundaries. It is because of this that they feature so prominently on the global register of significant geomorphosites. Arguably the most iconic of these basalt landscapes is the Giant's Causeway in Northern Ireland, a status recognized by its inscription as a World Heritage Site. Recognition at this level invariably brings visitor pressure, and with it concern as to the impact they exert on site integrity. Rarely, however, is the same overt concern expressed for the risks that such sites pose to the visitors - or not at least until disaster strikes. Yet, the very features that make these sites attractive - tall, exposed, largely unconstrained columns - render many of them intrinsically unstable, prone to catastrophic collapse and potentially hazardous to visitors. In this presentation we highlight the nature of these slope instability issues through a comparative analysis of two geographically contrasting basalt geomorphosites. Investigations of slope hazard at the Giant's Causeway have shown that many are linked to the distinctive structural characteristics and weathering patterns of flood basalts. Typically, individual flows comprise a columnar ‘colonnade', topped by a blocky ‘entablature' and separated from the flows above and below it by a structurally weaker, but often less-permeable, palaeosol that formed during periods of volcanic quiescence. The collapse of columns is often facilitated by a combination of weathering along ever-widening joints and wedging outwards by debris that falls into them. This gradual distortion of the colonnade makes columns increasingly susceptible to collapse. Often this is triggered by intense rainfall (perhaps following a dry spell) that rapidly infiltrates joints and is ponded on the underlying palaeosol. The precise nature of the failure (toppling or outwards rotation of the column base) is largely dictated by the nature of the

  19. Marine Science

    African Journals Online (AJOL)

    between humans and the coastal and marine environment. ... The journal has a new and more modern layout, published online only, and the editorial .... the population structure of Platorchestia fayetta sp. nov. and their interaction with the.

  20. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the ... tidal height and amplitude can influence light penetra- ...... to environmental parameters in cage culture area of Sepanggar Bay, Malaysia.

  1. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ... consist of special issues on major events or important thematic issues. ... of sources, including plant and animal by- products.

  2. Marine biotoxins

    National Research Council Canada - National Science Library

    2004-01-01

    ... (ciguatera fish poisoning). It discusses in detail the causative toxins produced by marine organisms, chemical structures and analytical methods, habitat and occurrence of the toxin-producing organisms, case studies and existing regulations...

  3. Marine Science

    African Journals Online (AJOL)

    pod diversity and distribution are important especially since studies on marine biodiversity are scarce .... Method II –. Zamoum &. Furla (2012) protocol. Method III. – Geist et al (2008) protocol ..... Public Library Of Science One 8: 51273.

  4. Marine pollution

    International Nuclear Information System (INIS)

    Clark, R.B.

    1992-01-01

    The effects of petroleum, waste materials, halogenated hydrocarbons, radioactivity and heat on the marine ecosystem, the fishing industry and human health are discussed using the example of the North Sea. (orig.) [de

  5. Marine Science

    African Journals Online (AJOL)

    No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form ... to optimize nucleic acid extraction protocols from marine gastropods, present an ...... Greenfield., Gomez E, Harvell CD, Sale PF, Edwards.

  6. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ..... circulation patterns include the nutrient-rich Somali ...... matical Structures in Computer Science 24: e240311.

  7. Marine insects

    National Research Council Canada - National Science Library

    Cheng, Lanna

    1976-01-01

    .... Not only are true insects, such as the Collembola and insect parasites of marine birds and mammals, considered, but also other kinds of intertidal air-breathing arthropods, notably spiders, scorpions...

  8. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue .... shell growth is adversely affected. ... local stressors in action, such as ocean acidification ..... that the distribution of many intertidal sessile animals.

  9. Genome analysis of the freshwater planktonic Vulcanococcus limneticus sp. nov. reveals horizontal transfer of nitrogenase operon and alternative pathways of nitrogen utilization.

    Science.gov (United States)

    Di Cesare, Andrea; Cabello-Yeves, Pedro J; Chrismas, Nathan A M; Sánchez-Baracaldo, Patricia; Salcher, Michaela M; Callieri, Cristiana

    2018-04-16

    Many cyanobacteria are capable of fixing atmospheric nitrogen, playing a crucial role in biogeochemical cycling. Little is known about freshwater unicellular cyanobacteria Synechococcus spp. at the genomic level, despite being recognised of considerable ecological importance in aquatic ecosystems. So far, it has not been shown whether these unicellular picocyanobacteria have the potential for nitrogen fixation. Here, we present the draft-genome of the new pink-pigmented Synechococcus-like strain Vulcanococcus limneticus. sp. nov., isolated from the volcanic Lake Albano (Central Italy). The novel species Vulcanococcus limneticus sp. nov. falls inside the sub-cluster 5.2, close to the estuarine/marine strains in a maximum-likelihood phylogenetic tree generated with 259 marker genes with representatives from marine, brackish, euryhaline and freshwater habitats. V.limneticus sp. nov. possesses a complete nitrogenase and nif operon. In an experimental setup under nitrogen limiting and non-limiting conditions, growth was observed in both cases. However, the nitrogenase genes (nifHDK) were not transcribed, i.e., V.limneticus sp. nov. did not fix nitrogen, but instead degraded the phycobilisomes to produce sufficient amounts of ammonia. Moreover, the strain encoded many other pathways to incorporate ammonia, nitrate and sulphate, which are energetically less expensive for the cell than fixing nitrogen. The association of the nif operon to a genomic island, the relatively high amount of mobile genetic elements (52 transposases) and the lower observed GC content of V.limneticus sp. nov. nif operon (60.54%) compared to the average of the strain (68.35%) support the theory that this planktonic strain may have obtained, at some point of its evolution, the nif operon by horizontal gene transfer (HGT) from a filamentous or heterocystous cyanobacterium. In this study, we describe the novel species Vulcanococcus limneticus sp. nov., which possesses a complete nif operon for

  10. Spaceborne Lidar in the Study of Marine Systems.

    Science.gov (United States)

    Hostetler, Chris A; Behrenfeld, Michael J; Hu, Yongxiang; Hair, Johnathan W; Schulien, Jennifer A

    2018-01-03

    Satellite passive ocean color instruments have provided an unbroken ∼20-year record of global ocean plankton properties, but this measurement approach has inherent limitations in terms of spatial-temporal sampling and ability to resolve vertical structure within the water column. These limitations can be addressed by coupling ocean color data with measurements from a spaceborne lidar. Airborne lidars have been used for decades to study ocean subsurface properties, but recent breakthroughs have now demonstrated that plankton properties can be measured with a satellite lidar. The satellite lidar era in oceanography has arrived. Here, we present a review of the lidar technique, its applications in marine systems, a perspective on what can be accomplished in the near future with an ocean- and atmosphere-optimized satellite lidar, and a vision for a multiplatform virtual constellation of observational assets that would enable a three-dimensional reconstruction of global ocean ecosystems.

  11. Spaceborne Lidar in the Study of Marine Systems

    Science.gov (United States)

    Hostetler, Chris A.; Behrenfeld, Michael J.; Hu, Yongxiang; Hair, Johnathan W.; Schulien, Jennifer A.

    2018-01-01

    Satellite passive ocean color instruments have provided an unbroken ˜20-year record of global ocean plankton properties, but this measurement approach has inherent limitations in terms of spatial-temporal sampling and ability to resolve vertical structure within the water column. These limitations can be addressed by coupling ocean color data with measurements from a spaceborne lidar. Airborne lidars have been used for decades to study ocean subsurface properties, but recent breakthroughs have now demonstrated that plankton properties can be measured with a satellite lidar. The satellite lidar era in oceanography has arrived. Here, we present a review of the lidar technique, its applications in marine systems, a perspective on what can be accomplished in the near future with an ocean- and atmosphere-optimized satellite lidar, and a vision for a multiplatform virtual constellation of observational assets that would enable a three-dimensional reconstruction of global ocean ecosystems.

  12. Plankton community structure and role of Oithona similis on the western coast of Greenland during the winter-spring transition

    DEFF Research Database (Denmark)

    Zamora-Terol, Sara; Nielsen, Torkel Gissel; Saiz, Enric

    2013-01-01

    The cyclopoid copepod Oithona similis is one of the most abundant copepods in the oceans, and has a potentially important role in pelagic food webs. However, there is a lack of knowledge on aspects of Oithona's biology and function in plankton communities. In the present study, we aimed to assess...... and compare its trophic role in Greenlandic coastal waters during the winter-spring transition, with a focus on its winter behaviour, when large calanoids are not present in the surface layer. Two locations were studied: waters offshore from Godthåbsfjord (Nuuk) in winter, and Qeqertarsuaq (Disko Bay...

  13. Photosynthetic planulae and planktonic hydroids: contrasting strategies of propagule survival

    Directory of Open Access Journals (Sweden)

    Patrizia Pagliara

    2000-12-01

    Full Text Available Settlement delays can be important to prevent propagule waste when proper settling substrates are not immediately available. Under laboratory conditions, the planulae of Clytia viridicans underwent two alternative developmental patterns. Some settled on the bottom, forming a hydranth-gonotheca complex that produced up to four medusae and later either degenerated or gave rise to a hydroid colony. Other planulae settled right below the air-water interface, forming floating colonies that eventually fell to the bottom and settled. Halecium nanum released planulae with a rich population of symbiotic zooxanthellae that survived into a rearing jar for three months. After a long period of apparent quiescence (possibly fuelled by photosynthetic activities of zooxanthellae the planulae produced new colonies. Both photosynthetic planulae and settlement at the interface air-water allow a delay in the passage from a planktonic to a fully functional benthic life.

  14. Escape response of planktonic protists to fluid mechanical signals

    DEFF Research Database (Denmark)

    Jakobsen, Hans Henrik

    2001-01-01

    The escape response to fluid mechanical signals was examined in 6 protists, 4 ciliates and 2 dinoflagellates. When exposed to a siphon flow. 3 species of ciliates, Balanion comatum, Strobilidium sp., and Mesodinium pulex, responded with escape jumps. The threshold deformation rates required...... times lower than that of a non-jumping similar sized protist when the predator was Temora longicornis, which captures prey entrained in a feeding current. However, when the predator was the ambush- feeding copepod Acartia tonsa, the predation mortalities of jumping and non-jumping protists were...... of similar magnitude. Escape responses may thus be advantageous in some situations. However, jumping behaviour may also enhance susceptibility to some predators, explaining the different predator avoidance strategies (jumping or not) that have evolved in planktonic protists....

  15. Why is relating plankton community structure to pelagic production ...

    African Journals Online (AJOL)

    spamer

    The conceptual framework for quantitative marine ecology is attributable to Victor Hensen (1887), who pro- ... As fish were being “harvested” by man, it was argued that relationships .... carry their own functional chloroplasts or else derive.

  16. 16S rRNA gene metabarcoding and TEM reveals different ecological strategies within the genus Neogloboquadrina (planktonic foraminifer.

    Directory of Open Access Journals (Sweden)

    Clare Bird

    Full Text Available Uncovering the complexities of trophic and metabolic interactions among microorganisms is essential for the understanding of marine biogeochemical cycling and modelling climate-driven ecosystem shifts. High-throughput DNA sequencing methods provide valuable tools for examining these complex interactions, although this remains challenging, as many microorganisms are difficult to isolate, identify and culture. We use two species of planktonic foraminifera from the climatically susceptible, palaeoceanographically important genus Neogloboquadrina, as ideal test microorganisms for the application of 16S rRNA gene metabarcoding. Neogloboquadrina dutertrei and Neogloboquadrina incompta were collected from the California Current and subjected to either 16S rRNA gene metabarcoding, fluorescence microscopy, or transmission electron microscopy (TEM to investigate their species-specific trophic interactions and potential symbiotic associations. 53-99% of 16S rRNA gene sequences recovered from two specimens of N. dutertrei were assigned to a single operational taxonomic unit (OTU from a chloroplast of the phylum Stramenopile. TEM observations confirmed the presence of numerous intact coccoid algae within the host cell, consistent with algal symbionts. Based on sequence data and observed ultrastructure, we taxonomically assign the putative algal symbionts to Pelagophyceae and not Chrysophyceae, as previously reported in this species. In addition, our data shows that N. dutertrei feeds on protists within particulate organic matter (POM, but not on bacteria as a major food source. In total contrast, of OTUs recovered from three N. incompta specimens, 83-95% were assigned to bacterial classes Alteromonadales and Vibrionales of the order Gammaproteobacteria. TEM demonstrates that these bacteria are a food source, not putative symbionts. Contrary to the current view that non-spinose foraminifera are predominantly herbivorous, neither N. dutertrei nor N. incompta

  17. A trait database for marine copepods

    Science.gov (United States)

    Brun, Philipp; Payne, Mark R.; Kiørboe, Thomas

    2017-02-01

    The trait-based approach is gaining increasing popularity in marine plankton ecology but the field urgently needs more and easier accessible trait data to advance. We compiled trait information on marine pelagic copepods, a major group of zooplankton, from the published literature and from experts and organized the data into a structured database. We collected 9306 records for 14 functional traits. Particular attention was given to body size, feeding mode, egg size, spawning strategy, respiration rate, and myelination (presence of nerve sheathing). Most records were reported at the species level, but some phylogenetically conserved traits, such as myelination, were reported at higher taxonomic levels, allowing the entire diversity of around 10 800 recognized marine copepod species to be covered with a few records. Aside from myelination, data coverage was highest for spawning strategy and body size, while information was more limited for quantitative traits related to reproduction and physiology. The database may be used to investigate relationships between traits, to produce trait biogeographies, or to inform and validate trait-based marine ecosystem models. The data can be downloaded from PANGAEA, PANGAEA.862968" target="_blank">doi:10.1594/PANGAEA.862968.

  18. Biomass changes and trophic amplification of plankton in a warmer ocean

    KAUST Repository

    Chust, Guillem

    2014-05-07

    Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3-D coupled physical-biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate-change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and

  19. Biomass changes and trophic amplification of plankton in a warmer ocean

    KAUST Repository

    Chust, Guillem; Allen, Julian Icarus; Bopp, Laurent; Schrum, Corinna; Holt, Jason T.; Tsiaras, Kostas P.; Zavatarelli, Marco; Chifflet, Marina; Cannaby, Heather; Dadou, Isabelle C.; Daewel, Ute; Wakelin, Sarah L.; Machú , Eric; Pushpadas, Dhanya; Butenschö n, Momme; Artioli, Yuri; Petihakis, George; Smith, Chris J M; Garç on, Vé ronique C.; Goubanova, Katerina; Le Vu, Briac; Fach, Bettina A.; Salihoglu, Baris; Clementi, Emanuela; Irigoien, Xabier

    2014-01-01

    Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3-D coupled physical-biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate-change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and

  20. Biomass changes and trophic amplification of plankton in a warmer ocean.

    Science.gov (United States)

    Chust, Guillem; Allen, J Icarus; Bopp, Laurent; Schrum, Corinna; Holt, Jason; Tsiaras, Kostas; Zavatarelli, Marco; Chifflet, Marina; Cannaby, Heather; Dadou, Isabelle; Daewel, Ute; Wakelin, Sarah L; Machu, Eric; Pushpadas, Dhanya; Butenschon, Momme; Artioli, Yuri; Petihakis, George; Smith, Chris; Garçon, Veronique; Goubanova, Katerina; Le Vu, Briac; Fach, Bettina A; Salihoglu, Baris; Clementi, Emanuela; Irigoien, Xabier

    2014-07-01

    Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3-D coupled physical-biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate-change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and

  1. Draft genome sequence of marine alphaproteobacterial strain HIMB11, the first cultivated representative of a unique lineage within the Roseobacter clade possessing an unusually small genome.

    Science.gov (United States)

    Durham, Bryndan P; Grote, Jana; Whittaker, Kerry A; Bender, Sara J; Luo, Haiwei; Grim, Sharon L; Brown, Julia M; Casey, John R; Dron, Antony; Florez-Leiva, Lennin; Krupke, Andreas; Luria, Catherine M; Mine, Aric H; Nigro, Olivia D; Pather, Santhiska; Talarmin, Agathe; Wear, Emma K; Weber, Thomas S; Wilson, Jesse M; Church, Matthew J; DeLong, Edward F; Karl, David M; Steward, Grieg F; Eppley, John M; Kyrpides, Nikos C; Schuster, Stephan; Rappé, Michael S

    2014-06-15

    Strain HIMB11 is a planktonic marine bacterium isolated from coastal seawater in Kaneohe Bay, Oahu, Hawaii belonging to the ubiquitous and versatile Roseobacter clade of the alphaproteobacterial family Rhodobacteraceae. Here we describe the preliminary characteristics of strain HIMB11, including annotation of the draft genome sequence and comparative genomic analysis with other members of the Roseobacter lineage. The 3,098,747 bp draft genome is arranged in 34 contigs and contains 3,183 protein-coding genes and 54 RNA genes. Phylogenomic and 16S rRNA gene analyses indicate that HIMB11 represents a unique sublineage within the Roseobacter clade. Comparison with other publicly available genome sequences from members of the Roseobacter lineage reveals that strain HIMB11 has the genomic potential to utilize a wide variety of energy sources (e.g. organic matter, reduced inorganic sulfur, light, carbon monoxide), while possessing a reduced number of substrate transporters.

  2. Plankton as an indicator of the temporal variation of the Chernobyl fallout

    International Nuclear Information System (INIS)

    Ravera, O.; Giannoni, L.

    1995-01-01

    Here we describe the pattern of radionuclide activities (iodine-131; cesium-134; cesium-137; ruthenium-106) in net-plankton and water samples collected from two lakes in Northern Italy (Lake Monate and Lake Comabbio) during and after the presence in the area of the radioactive cloud from the Chernobyl accident: from 30 April to 3 September 1986. The results show that, because of its short lifespan, plankton is a good indicator of daily variations of environmental contamination. The contamination level of plankton depends on various factors, such as the speciation and biological role of the radionuclide, the community structure and chemical characteristics of the water

  3. Temperature, salinity, transmissivity, pressure, plankton, oxygen, nutrients, chlorophyll, and primary productivity data collected using CTD, bottle, and plankton net from the R/V Italica in the Ross Sea and Magellan Strait during 10th Italian Antarctic Expedition from 1994-11-13 to 1995-04-02 (NCEI Accession 0068289)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, transmissivity, pressure, plankton, oxygen, nutrients, chlorophyll, and primary productivity data collected using CTD, bottle, and plankton...

  4. Community cascades in a marine pelagic food web controlled by the non-visual apex predator Mnemiopsis leidyi

    DEFF Research Database (Denmark)

    Tiselius, Peter; Møller, Lene Friis

    2017-01-01

    Trophic cascades are a ubiquitous feature of many terrestrial and fresh-water food webs, but have been difficult to demonstrate in marine systems with multispecies trophic levels. Here we describe significant trophic cascades in an open coastal planktonic ecosystem exposed to an introduced top...... predator. The ctenophore Mnemiopsis leidyi was monitored for an 8-year period concurrent with measures of the food web structure of the plankton and strong trophic cascades were evident. In the 5 years when M. leidyi were found, their target prey (grazing copepods) were reduced 5-fold and the primary...

  5. The old and the new plankton: ecological replacement of associations of mollusc plankton and giant filter feeders after the Cretaceous?

    Directory of Open Access Journals (Sweden)

    Amane Tajika

    2018-01-01

    Full Text Available Owing to their great diversity and abundance, ammonites and belemnites represented key elements in Mesozoic food webs. Because of their extreme ontogenetic size increase by up to three orders of magnitude, their position in the food webs likely changed during ontogeny. Here, we reconstruct the number of eggs laid by large adult females of these cephalopods and discuss developmental shifts in their ecologic roles. Based on similarities in conch morphology, size, habitat and abundance, we suggest that similar niches occupied in the Cretaceous by juvenile ammonites and belemnites were vacated during the extinction and later partially filled by holoplanktonic gastropods. As primary consumers, these extinct cephalopod groups were important constituents of the plankton and a principal food source for planktivorous organisms. As victims or, respectively, profiteers of this case of ecological replacement, filter feeding chondrichthyans and cetaceans likely filled the niches formerly occupied by large pachycormid fishes during the Jurassic and Cretaceous.

  6. The planktonic communities of the Jamaican south-east coast; a comparison of harbor, shelf and oceanic areas

    Directory of Open Access Journals (Sweden)

    Hugh Small

    2014-09-01

    Full Text Available Few studies have compared water quality and plankton along the eutrophication gradient from Kingston Harbour to oceanic waters around Jamaica. To compare the planktonic community along the expected nutrient gradient, we sampled every two weeks at four stations, from eutrophic Kingston Harbour to oceanic California Bank. Phytoplankton was assessed from whole water Niskin bottle casts and zooplankton by vertical hauls with plankton nets of three different mesh sizes: 64µm, 200µm, and 600µm. Total phytoplankton biomass declined sharply away from the harbour (1.0 μg L-1 at the Harbour Shoal Beacon to 0.2 μg L-1 at California Bank. Characteristic estuarine phytoplankton genera -such as Ceratium, Gonyaulax, Gyrodinium and Rhizosolenia- dominated harbour samples while genera characteristic of offshore locations -such as Asterionelliopsis, Navicula, Nitzschia, Rhizosolenia and Thalassionema- dominated California Bank. Highest phytoplankton densities (mean values of 34 174 cells L-1 were found at the harbor mouth. Mean zooplankton abundances ranged from maximum (5 858.5m-3 at Beacon to minimum (2 124.2 m-3 at California; 171 species of zooplankton were identified and copepods dominated with 76 species. Overall, 75 species of zooplankton were identified from Beacon, 107 from Port Royal Cays- South East Cay, 110 from the exposed shelf edge- Windward Edge, and 95 from the oceanic California Bank. Larval forms dominated; copepod nauplii, fish eggs and echinoderm larvae occurred at all sites. Lucifer faxoni and Penilia avirostris were indicative of harbor waters and Microsetella sp. and Farranula carinata of offshore waters. Some zooplankton taxa, like L. faxoni, Paracalanus parvus and copepod nauplii, despite showing gradual decline with distance from Beacon to the Edge, increased in abundance at the furthest station, California. California Bank clearly experiences enrichment which at times can be as high as near-shore areas, but the planktonic

  7. Astronomically forced paleoclimate change from middle Eocene to early Oligocene: continental conditions in central China compared with the global marine isotope record

    Science.gov (United States)

    Huang, C.; Hinnov, L. A.

    2010-12-01

    The early Eocene climatic optimum ended with a long interval of global cooling that began in the early Middle Eocene and ended at the Eocene-Oligocene transition. During this long-term cooling, a series of short-term warming reversals occurred in the marine realm. Here, we investigate corresponding continental climate conditions as revealed in the Qianjiang Formation of the Jianghan Basin in central China, which consists of more than 4000 m of saline lake sediments. The Qianjiang Formation includes, in its deepest sections, a halite-rich rhythmic sediment succession with dark mudstone, brownish-white siltstone and sandstone, and greyish-white halite. Alternating fresh water (humid/cool)—saline water (dry/hot) deposits reflect climate cycles driven by orbital forcing. High-resolution gamma ray (GR) logging from the basin center captures these pronounced lithological rhythms throughout the formation. Several halite-rich intervals are interpreted as short-term warming events within the middle Eocene to early Oligocene, and could be expressions of coeval warming events in the global marine oxygen isotope record, for example, the middle Eocene climate optimum (MECO) event around 41 Ma. The Eocene-Oligocene boundary is distinguished by a radical change from halite-rich to clastic sediments, indicating a dramatic climate change from warm to cool conditions. Power spectral analysis of the GR series indicates strong short (~100 kyr) eccentricity cycling during the warm/hot episodes. Amplitude modulation of the short eccentricity in the GR series occurs with a strong 405 kyr periodicity. This cycling is calibrated to the La2004 orbital eccentricity model. A climate reversal occurs at 36.5 Ma within the long-term marine cooling trend following MECO, which is reflected also in the Qianjiang GR series, with the latter indicating several brief warm/dry reversals within the trend. A ~2.6 Myr halite-rich warm interval occurs in the latest Eocene in the continental record; both

  8. Marine Natural Products from New Caledonia—A Review

    Directory of Open Access Journals (Sweden)

    Sofia-Eléna Motuhi

    2016-03-01

    Full Text Available Marine micro- and macroorganisms are well known to produce metabolites with high biotechnological potential. Nearly 40 years of systematic prospecting all around the New Caledonia archipelago and several successive research programs have uncovered new chemical leads from benthic and planktonic organisms. After species identification, biological and/or pharmaceutical analyses are performed on marine organisms to assess their bioactivities. A total of 3582 genera, 1107 families and 9372 species have been surveyed and more than 350 novel molecular structures have been identified. Along with their bioactivities that hold promise for therapeutic applications, most of these molecules are also potentially useful for cosmetics and food biotechnology. This review highlights the tremendous marine diversity in New Caledonia, and offers an outline of the vast possibilities for natural products, especially in the interest of pursuing collaborative fundamental research programs and developing local biotechnology programs.

  9. Contribution of fish to the marine inorganic carbon cycle.

    Science.gov (United States)

    Wilson, R W; Millero, F J; Taylor, J R; Walsh, P J; Christensen, V; Jennings, S; Grosell, M

    2009-01-16

    Oceanic production of calcium carbonate is conventionally attributed to marine plankton (coccolithophores and foraminifera). Here we report that marine fish produce precipitated carbonates within their intestines and excrete these at high rates. When combined with estimates of global fish biomass, this suggests that marine fish contribute 3 to 15% of total oceanic carbonate production. Fish carbonates have a higher magnesium content and solubility than traditional sources, yielding faster dissolution with depth. This may explain up to a quarter of the increase in titratable alkalinity within 1000 meters of the ocean surface, a controversial phenomenon that has puzzled oceanographers for decades. We also predict that fish carbonate production may rise in response to future environmental changes in carbon dioxide, and thus become an increasingly important component of the inorganic carbon cycle.

  10. THE EARLY PLIOCENE MAMMAL ASSEMBLAGE OF VAL DI PUGNA (TUSCANY, ITALY IN THE LIGHT OF CALCAREOUS PLANKTON BIOSTRATIGRAPHICAL DATA AND PALEOECOLOGICAL OBSERVATIONS

    Directory of Open Access Journals (Sweden)

    GIOVANNI BIANUCCI

    2001-11-01

    Full Text Available The stratigraphy of clayey and sandy beds outcropping in Val di Pugna locality near Siena (Tuscany, Italy celebrated for the past finds of fossil mammalian remains, is studied here. The research is aimed to date and define the depositional environment of the sediments that yielded fossil bones of known provenance.  Two sequences have been studied in detail; they are located near the hamlets of Ruffolo and Case il Poggio, where both marine and land mammal remains had been found. The integrated biostratigraphic analysis of the planktonic foraminifers and calcareous nannoplankton indicates that the deposits straddle the transition from the Zone MPL3 to MPL4 of the planktonic foraminifer biostratigraphic scale, which is correlated with the Reticulofenestra pseudoumbilicus Zone (MNN14-15 Zone of the calcareous nannoplankton scale. The sedimentary characters and the faunal content are suggestive of a progressively deepening marine environment, with a transition from upper shoreface deposits to lower shoreface-offshore deposits. The vertebrates include a cetacean (Tusciziphis crispus and a sirenid (Metaxyterium gervaisi amongst the marine mammals, while the land mammals are represented by a rhino (Stephanorhinus jeanvireti and a bovid (Alephis lyrix. The sirenid remains are likely the only autochthonous elements because of their ecologic consistency with the depositional environment of the embedding sediments. The other fossil specimens are interpreted here as parts of decaying and floating carcasses that deposited their bones as they drifted away, inflated by decomposition gasses.The biostratigraphy of the sites permits to date the fossil bones. Noteworthy occurrences are those of Stephanorhinus jeanvireti and Alephis lyrix in levels correlated with Zone MN14, since they are usually reported in Zone MN16 and Zone MN15 assemblages, respectively.   

  11. Marine Battlefields

    DEFF Research Database (Denmark)

    Harðardóttir, Sara

    as they are an important food source for various marine animals. For both phytoand zooplankton predation is a major cause of mortality, and strategies for protection or avoidance are important for survival. Diatoms of the genera Nitzschia and Pseudo-nitzschia are known to produce a neuro-toxin, domoic acid (DA). Despite......Phytoplankton species are photosynthetic organisms found in most aquatic habitats. In the ocean, phytoplankton are tremendously important because they produce the energy that forms the base of the marine food web. Zooplankton feed on phytoplankton and mediate the energy to higher trophic levels...

  12. Marine biodiversity in Colombia

    International Nuclear Information System (INIS)

    Diaz, Juan Manuel

    2002-01-01

    One decade ago, the seas and oceans were considered biologically less diverse that the terrestrial environment. Now it is known that it is on the contrary; 33 of the 34 categories of animals (phylum), they are represented in the sea, compared with those solely 15 that exist in earth. The investigation about the diversity of life in the sea has been relatively scorned, but there are big benefits that we can wait if this is protected. The captures of fish depend on it; the species captured by the fisheries are sustained of the biodiversity of their trophic chains and habitats. The marine species are probably the biggest reservoir of chemical substances that can be used in pharmaceutical products. The genetic material of some species can be useful in biotechnical applications. The paper treats topics like the current state of the knowledge in marine biodiversity and it is done a diagnostic of the marine biodiversity in Colombia

  13. Experimental assessment of cumulative temperature and UV-B radiation effects on Mediterranean plankton metabolism

    KAUST Repository

    Garcia-Corral, Lara S.; Martinez Ayala, Juan; Duarte, Carlos M.; Agusti, Susana

    2015-01-01

    . The oligotrophic waters are already highly transparent, however, exposure of Mediterranean plankton to ultraviolet radiation (UV-B and UV-A) may increase further if the waters become more oligotrophic, thereby, allowing a deeper UV radiation penetration and likely

  14. Planktonic foraminifera from a quaternary deep sea core from the southern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Rao, P.S.; Pattan, J.N.

    An investigation on planktonic foraminifera and calcium carbonate content of a box core collected at a depth of 2556 m from the southern part of the Arabian sea indicates faunal changes depicting Quaternary climatic fluctuations. Based on the study...

  15. Modeling the distribution of colonial species to improve estimation of plankton concentration in ballast water

    Science.gov (United States)

    Rajakaruna, Harshana; VandenByllaardt, Julie; Kydd, Jocelyn; Bailey, Sarah

    2018-03-01

    The International Maritime Organization (IMO) has set limits on allowable plankton concentrations in ballast water discharge to minimize aquatic invasions globally. Previous guidance on ballast water sampling and compliance decision thresholds was based on the assumption that probability distributions of plankton are Poisson when spatially homogenous, or negative binomial when heterogeneous. We propose a hierarchical probability model, which incorporates distributions at the level of particles (i.e., discrete individuals plus colonies per unit volume) and also within particles (i.e., individuals per particle) to estimate the average plankton concentration in ballast water. We examined the performance of the models using data for plankton in the size class ≥ 10 μm and test ballast water compliance using the above models.

  16. An Experimental-Numerical Study of Small Scale Flow Interaction with Bioluminescent Plankton

    National Research Council Canada - National Science Library

    Latz, Michael

    1998-01-01

    Numerical and experimental approaches were used to investigate the effects of quantified flow stimuli on bioluminescence sUmulatidn at the small length and time scales appropriate for individual plankton...

  17. Sediment traps as a new tool for estimation of longevity of planktonic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    Sediment trap technique provides time series data of sinking particles (faunal and sediment) from surface to bottom of the sea. Besides many other applications, data can also be used to estimate life span of planktonic foraminifera. Based on rearing...

  18. Response of planktonic bacteria of New Calabar River to zinc stress ...

    African Journals Online (AJOL)

    Response of planktonic bacteria of New Calabar River to zinc stress. ... The result of the in vitro study indicated that the bacterial strains are sensitive to Zn2+ stress. Therefore, Zn2+ contamination would ... Featuring journals from 32 Countries:.

  19. Influence of monsoon upwelling on the planktonic foraminifera off Oman during Late Quaternary

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    Planktonic foraminifer abundances, fluxes, test sizes, and coiling properties are influenced in various ways by the southwest monsoon winds and associated upwelling in the western Arabian Sea. The influence of monsoon driven upwelling...

  20. Sensitivity of planktonic and biofilm-associated Aeromonas spp. to ionizing radiation

    International Nuclear Information System (INIS)

    Nagar, Vandan; Bandekar, J.R.

    2015-01-01

    Genus Aeromonas has emerged as an important human pathogen because it causes a variety of diseases including gastroenteritis and extra-intestinal infections. Aeromonas have the ability to adhere and form biofilms on food surfaces and food contact surfaces. Biofilm formation on foods and food contact surfaces is the major reason for contamination, cross contamination and post-processing contamination of the final food product leading to food spoilage, product rejection, economic losses and food-borne diseases. Biofilms have shown high resistance to heat, desiccation, acidic condition, high salt concentration, antibiotics and other food preservatives. Earlier studies in our laboratory have shown that ionizing radiation effectively inactivates Aeromonas in different food products. However, the relative efficacy of this process against biofilm associated cells versus free-living planktonic cells of Aeromonas is not well documented. Therefore, the dose of gamma radiation required to reduce the population by 90% (D10) was calculated for planktonic and biofilm-associated A. salmonicida Y567 and A. hydrophila A331 cells. Both A. hydrophila A331 and A. salmonicida Y567 expressed significant ability to attach and grow on glass surface following incubation at 30℃ in TSB. Ionizing radiation effectively reduced the populations of both planktonic and biofilm-associated cells for both the strains. Mean cell counts of survivors and surviving fraction of planktonic and biofilm-associated cells decreased with increased irradiation doses. The D10 values of planktonic cells and biofilm cells for A. salmonicida (Y567) were 232.65 Gy and 248.41 Gy, respectively; whereas, the D10 values of planktonic cells and biofilm cells for A. hydrophila (A331) were 249.2 Gy and 240.2 Gy respectively. No significant difference in the D10 values of planktonic and biofilm associated Aeromonas was observed. The influence of the cultured state of the organism, i.e., planktonic versus biofilm associated

  1. Factors Affecting Catalase Expression in Pseudomonas aeruginosa Biofilms and Planktonic Cells

    OpenAIRE

    Frederick, Jesse R.; Elkins, James G.; Bollinger, Nikki; Hassett, Daniel J.; McDermott, Timothy R.

    2001-01-01

    Previous work with Pseudomonas aeruginosa showed that catalase activity in biofilms was significantly reduced relative to that in planktonic cells. To better understand biofilm physiology, we examined possible explanations for the differential expression of catalase in cells cultured in these two different conditions. For maximal catalase activity, biofilm cells required significantly more iron (25 μM as FeCl3) in the medium, whereas planktonic cultures required no addition of iron. However, ...

  2. Emergent Patterns of Diversity and Dynamics in Natural Populations of Planktonic Vibrio Bacteria

    Science.gov (United States)

    2005-06-01

    1973. Ecology of Vibrio parahemolyticus in mixed-template amplifications: formation, consequences and elimination by Chesapeake Bay. J. Bacteriol. 113...Science 1930 and Engineering DOCTORAL DISSERTATION Emergent Patterns of Diversity and Dynamics in Natural Populations of Planktonic Vibrio Bacteria by...DYNAMICS IN NATURAL POPULATIONS OF PLANKTONIC VIBRIO BACTERIA by Janelle Ren6e Thompson B.S. Biological Sciences, Stanford University 1998 M.S

  3. Marine Science

    African Journals Online (AJOL)

    Science. The journal has a new and more modern layout, published online only, and the editorial. Board was increased to include more disciplines pertaining to marine sciences. While important chal- lenges still lie ahead, we are steadily advancing our standard to increase visibility and dissemination throughout the global ...

  4. Marine Mammals.

    Science.gov (United States)

    Meith, Nikki

    Marine mammals have not only fascinated and inspired human beings for thousands of years, but they also support a big business by providing flesh for sea-borne factories, sustaining Arctic lifestyles and traditions, and attracting tourists to ocean aquaria. While they are being harpooned, bludgeoned, shot, netted, and trained to jump through…

  5. Marine Science

    African Journals Online (AJOL)

    Mauritius Marine Conservation Society through their. Abstract. While no populations of seals are resident in the tropical Indian Ocean, vagrant animals are occasionally sighted in the region. Here we detail two new sightings of pinnipeds in the Mascarene Islands (Mauritius, Reunion and Rodri- gues) since 1996 and review ...

  6. Marine Science

    African Journals Online (AJOL)

    J O U R N A L O F. Marine Science. Coral reefs of Mauritius in a changing global climate ..... in confined aquifers, and a lesser influence in uncon- fined systems. On the ... massive cloud cover during the critical months, some. 70% bleaching ...

  7. Marine Science

    African Journals Online (AJOL)

    Copy Editor Timothy Andrew. Published ... 2007; Zhou et al., 2009) and they play an important role in the ... At both sites, zonal variation in TMPB was evident with significantly higher C-biomass closer to ... ton is considered to be an essential parameter in eco- systems ...... logical significance of toxic marine dinoflagellates.

  8. Marine Science

    African Journals Online (AJOL)

    sustainable coastal development in the region, as well as contributing to the ... between humans and the coastal and marine environment. ... exploitation for timber, fuel wood, aquaculture, urban. Abstract. Given the high dependence of coastal communities on natural resources, mangrove conservation is a challenge in.

  9. Marine Science

    African Journals Online (AJOL)

    No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means ... USA/Norway ... The last couple of years have been a time of change for the Western Indian Ocean Journal of Marine.

  10. Marine Science

    African Journals Online (AJOL)

    Chief Editor José Paula | Faculty of Sciences of University of Lisbon, Portugal. Copy Editor Timothy Andrew. Published biannually. Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) ...

  11. Abundance of plankton population densities in relation to bottom soil textural types in aquaculture ponds

    Directory of Open Access Journals (Sweden)

    F. Siddika

    2012-06-01

    Full Text Available Plankton is an important food item of fishes and indicator for the productivity of a water body. The present study was conducted to evaluate the effects of bottom soil textural conditions on abundance of plankton in aquaculture pond. The experiment was carried out using three treatments, i.e., ponds bottom with sandy loam (T1, with loam (T2 and with clay loam (T3. The ranges of water quality parameters analyzed were suitable for the growth of plankton during the experimental period. Similarly, chemical properties of soil were also within suitable ranges and every parameter showed higher ranges in T2. A total 20 genera of phytoplankton were recorded belonged to Chlorophyceae (7, Cyanophyceae (5, Bacillariophyceae (5, Euglenophyceae (2 and Dinophyceae (1. On the other hand, total 13 genera of zooplankton were recorded belonged to Crustacea (7 and Rotifera (6. The highest ranges of phytoplankton and zooplankton densities were found in T2 where low to medium-type bloom was observed during the study period. Consequently, the mean abundance of plankton (phytoplankton and zooplankton density was significantly highest in T2. The highest abundance of plankton in the T2 indicated that pond bottom with loamy soil is suitable for the growth and production of plankton in aquaculture ponds.

  12. UV sensitivity of planktonic net community production in ocean surface waters

    Science.gov (United States)

    Regaudie-de-Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-05-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we test the sensitivity of net community production (NCP) to UVB of planktonic communities in surface waters across contrasting regions of the ocean. We observed here that UVB radiation affects net plankton community production at the ocean surface, imposing a shift in NCP by, on average, 50% relative to the values measured when excluding partly UVB. Our results show that under full solar radiation, the metabolic balance shows the prevalence of net heterotrophic community production. The demonstration of an important effect of UVB radiation on NCP in surface waters presented here is of particular relevance in relation to the increased UVB radiation derived from the erosion of the stratospheric ozone layer. Our results encourage design future research to further our understanding of UVB effects on the metabolic balance of plankton communities.

  13. Ecological-network models link diversity, structure and function in the plankton food-web

    Science.gov (United States)

    D'Alelio, Domenico; Libralato, Simone; Wyatt, Timothy; Ribera D'Alcalà, Maurizio

    2016-02-01

    A planktonic food-web model including sixty-three functional nodes (representing auto- mixo- and heterotrophs) was developed to integrate most trophic diversity present in the plankton. The model was implemented in two variants - which we named ‘green’ and ‘blue’ - characterized by opposite amounts of phytoplankton biomass and representing, respectively, bloom and non-bloom states of the system. Taxonomically disaggregated food-webs described herein allowed to shed light on how components of the plankton community changed their trophic behavior in the two different conditions, and modified the overall functioning of the plankton food web. The green and blue food-webs showed distinct organizations in terms of trophic roles of the nodes and carbon fluxes between them. Such re-organization stemmed from switches in selective grazing by both metazoan and protozoan consumers. Switches in food-web structure resulted in relatively small differences in the efficiency of material transfer towards higher trophic levels. For instance, from green to blue states, a seven-fold decrease in phytoplankton biomass translated into only a two-fold decrease in potential planktivorous fish biomass. By linking diversity, structure and function in the plankton food-web, we discuss the role of internal mechanisms, relying on species-specific functionalities, in driving the ‘adaptive’ responses of plankton communities to perturbations.

  14. [Effect of Pseudomonas aeruginosa exometabolites on planktonic and biofilm cultures of Escherichia coli].

    Science.gov (United States)

    Kuznetsova, M V; Karpunina, T I; Maslennikova, I L; Nesterova, L Iu; Demakov, V A

    2012-01-01

    Study the effect of P. aeruginosa exometabolites on planktonic and biofilm cultures of bioluminescent E. coli strain. E. coli K12 TG1 (pF1 lux+ Ap(r)) recombinant bioluminescent strain, P. aeruginosa ATCC 27853 reference strain and 2 nosocomial isolates were used. Pyocyanin and pyoverdin content in supernatant of P. aeruginosa over-night cultures was evaluated according to E. Deziel et al. (2001). Planktonic and biofilm cultures of E. coli were obtained in 96-well plates (LB, statically, 37 degrees C), optical density of plankton, film biomass (OD600, OD580) and bioluminescence in plankton and biofilm were evaluated in microplate reader Infiniti M200 (Tecan, Austria). P. aeruginosa exometabolites increased the duration of lag-phase in E. coli, and short term exposition inhibited luminescence of planktonic cells. These effects are determined by bactericidal action ofpyocyanin and pyoverdin. Supernatants ofover-night cultures of P. aeruginosa inhibit formation of biofilm and disrupt the formed biofilm of E. coli. Effect of pyocyanin and pyoverdin on these processes is not established, other factors may have higher significance. Bioluminescence of E. coli K12 TGI that reflects the energetic status of the cell allows to evaluate and prognose the character of coexistence of P. aeruginosa in combined with E. coli planktonic and biofilm culture.

  15. Seasonal variation of plankton communities influenced by environmental factors in an artificial lake

    Science.gov (United States)

    Li, Xuemei; Yu, Yuhe; Zhang, Tanglin; Feng, Weisong; Ao, Hongyi; Yan, Qingyun

    2012-05-01

    We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA and 18S rRNA genes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis ( R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis ( R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.

  16. Biogenic Properties of Deep Waters from the Black Sea Reduction (Hydrogen Sulphide) Zone for Marine Algae

    OpenAIRE

    Polikarpov, Gennady G.; Lazorenko, Galina Е.; Тereschenko, Natalya N.

    2015-01-01

    Abstract Generalized data of biogenic properties investigations of the Black Sea deep waters from its reduction zone for marine algae are presented. It is shown on board and in laboratory that after pre-oxidation of hydrogen sulphide by intensive aeration of the deep waters lifted to the surface of the sea, they are ready to be used for cultivation of the Black Sea unicellular, planktonic, and multicellular, benthic, algae instead of artificial medium. Naturally balanced micro- and macroeleme...

  17. Spatial and Temporal Water Quality Dynamics in the Lake Maumelle Reservoir (Arkansas): Geochemical and Planktonic Variance in a Drinking Water Source

    Science.gov (United States)

    Carey, M. D.; Ruhl, L. S.

    2017-12-01

    The Lake Maumelle reservoir is Central Arkansas's main water supply. Maintaining a high standard of water quality is important to the over 400,000 residents of this area whom rely on this mesotrophic waterbody for drinking water. Lake Maumelle is also a scenic attraction for recreational boating and fishing. Past research has focused primarily on watershed management with land use/land cover modeling and quarterly water sampling of the 13.91mi2 reservoir. The surrounding land within the watershed is predominately densely forested, with timber farms and the Ouachita National Forest. This project identifies water quality changes spatially and temporally, which have not been as frequently observed, over a 6-month timespan. Water samples were collected vertically throughout the water column and horizontally throughout the lake following reservoir zonation. Parameters collected vertically for water quality profiles are temperature, dissolved oxygen, electrical conductivity, salinity, and pH. Soft sediment samples were collected and pore water was extracted by centrifuge. Cation and anion concentrations in the water samples were determined using ion chromatography, and trace element concentrations were determined using ICPMS. Planktonic abundances were determined using an inverted microscope and a 5ml counting chamber. Trace element, cation, and anion concentrations have been compared with planktonic abundance and location to determine microorganismal response to geochemical variance. During June 2017 sampling, parameters varied throughout the water column (temperature decreased 4 degrees Celsius and dissolved oxygen decreased from 98% to 30% from surface to bottom depths), revealing that the reservoir was becoming stratified. Collected plankton samples revealed the presence of copepod, daphnia, and dinoflagellate algae. Utricularia gibba was present in the littoral zone. Low electrical conductivity readings and high water clarity are consistent with the lake

  18. Marine intervals in Neogene fluvial deposits of western Amazonia

    Science.gov (United States)

    Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

    2014-05-01

    Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

  19. Eukaryotic Plankton Species Diversity in the Western Channel of the Korea Strait using 18S rDNA Sequences and its Implications for Water Masses

    Science.gov (United States)

    Lee, Sang-Rae; Song, Eun Hye; Lee, Tongsup

    2018-03-01

    Organisms entering the East Sea (Sea of Japan) through the Korea Strait, together with water, salt, and energy, affect the East Sea ecosystem. In this study, we report on the biodiversity of eukaryotic plankton found in the Western Channel of the Korea Strait for the first time using small subunit ribosomal RNA gene (18S rDNA) sequences. We also discuss the characteristics of water masses and their physicochemical factors. Diverse taxonomic groups were recovered from 18S rDNA clone libraries, including putative novel, higher taxonomic entities affiliated with Cercozoa, Raphidophyceae, Picozoa, and novel marine Stramenopiles. We also found that there was cryptic genetic variation at both the intraspecific and interspecific levels among arthropods, diatoms, and green algae. Specific plankton assemblages were identified at different sampling depths and they may provide useful information that could be used to interpret the origin and the subsequent mixing history of the water masses that contribute to the Tsushima Warm Current waters. Furthermore, the biological information highlighted in this study may help improve our understanding about the complex water mass interactions that were highlighted in the Korea Strait.

  20. Ingestion and transfer of microplastics in the planktonic food web

    International Nuclear Information System (INIS)

    Setälä, Outi; Fleming-Lehtinen, Vivi; Lehtiniemi, Maiju

    2014-01-01

    Experiments were carried out with different Baltic Sea zooplankton taxa to scan their potential to ingest plastics. Mysid shrimps, copepods, cladocerans, rotifers, polychaete larvae and ciliates were exposed to 10 μm fluorescent polystyrene microspheres. These experiments showed ingestion of microspheres in all taxa studied. The highest percentage of individuals with ingested spheres was found in pelagic polychaete larvae, Marenzelleria spp. Experiments with the copepod Eurytemora affinis and the mysid shrimp Neomysis integer showed egestion of microspheres within 12 h. Food web transfer experiments were done by offering zooplankton labelled with ingested microspheres to mysid shrimps. Microscopy observations of mysid intestine showed the presence of zooplankton prey and microspheres after 3 h incubation. This study shows for the first time the potential of plastic microparticle transfer via planktonic organisms from one trophic level (mesozooplankton) to a higher level (macrozooplankton). The impacts of plastic transfer and possible accumulation in the food web need further investigations. -- Highlights: • Experiments show the potential of ingestion of plastics by various zooplankton taxa. • This ingestion of plastics can be indirect via other zooplankton organisms. • There may be several alternate routes for microplastic transfer in the food webs. -- Experiments with zooplankton and microspheres showed ingestion of spheres by zpl and the transfer of ingested microspheres to higher trophic level organisms via labelled zooplankton

  1. A light-induced shortcut in the planktonic microbial loop

    Science.gov (United States)

    Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martínez, Rodrigo A.; Schabhüttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

    2016-07-01

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  2. A light-induced shortcut in the planktonic microbial loop

    KAUST Repository

    Ptacnik, Robert

    2016-07-11

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  3. A light-induced shortcut in the planktonic microbial loop

    KAUST Repository

    Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martí nez, Rodrigo A.; Schabhü ttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

    2016-01-01

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  4. Why is relating plankton community structure to pelagic production ...

    African Journals Online (AJOL)

    mixing regulates primary production, and assuming certain features of food-chain length and efficiency, one can estimate fish yields. Fundamental to these arguments are assumptions concerning resource limitation which appear to be uncertain as generic marine pelagic characteristics, primarily that trophic levels are ...

  5. Potential of medicinal plants from the Brazilian semi-arid region (Caatinga) against Staphylococcus epidermidis planktonic and biofilm lifestyles.

    Science.gov (United States)

    Trentin, Danielle da Silva; Giordani, Raquel Brandt; Zimmer, Karine Rigon; da Silva, Alexandre Gomes; da Silva, Márcia Vanusa; Correia, Maria Tereza Dos Santos; Baumvol, Israel Jacob Rabin; Macedo, Alexandre José

    2011-09-01

    Medicinal plants from the Caatinga, a Brazilian xeric shrubland, are used in folk medicine to treat infections. These ethnopharmacological data can contribute to obtaining new antimicrobial/antibiofilm extracts and natural product prototypes for the development of new drugs. The aim of this study was to investigate the antibiofilm and antibacterial activities of 45 aqueous extracts from 24 Caatinga plant species. The effect of aqueous extracts on planktonic cells and on biofilm formation by Staphylococcus epidermidis was studied by the OD(600) absorbance and by the crystal violet assay, respectively. Scanning electron microscopy (SEM) was used to generate comparative images of extract-treated and untreated biofilms. Chromatographic analyses were performed to characterize the active extracts. The in vitro screening, at 0.4 mg/mL and 4.0mg/mL, showed 20 plants effective in preventing biofilm formation and 13 plants able to inhibit planktonic bacterial growth. SEM images demonstrated distinct profiles of bacterial adhesion, matrix production and cell morphology according to different treatments and surfaces. The phytochemical analysis of the selected active extracts indicates the polyphenols, coumarins, steroids and terpenes as possible active compounds. This study describes the first antibiofilm and antibacterial screening of Caatinga plants against S. epidermidis. The evaluation presented in this study confirms several ethnopharmacological reports and can be utilized to identify new antibiofilm and antibacterial products against S. epidermidis from traditional Brazilian medicine. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  6. C-di-GMP regulates Pseudomonas aeruginosa stress response to tellurite during both planktonic and biofilm modes of growth

    DEFF Research Database (Denmark)

    Chua, Song Lin; Sivakumar, Krishnakumar; Rybtke, Morten Levin

    2015-01-01

    tellurite (TeO3(2-)) exposure induced the intracellular content of the secondary messenger cyclic di-GMP (c-di-GMP) of Pseudomonas aeruginosa. Two diguanylate cyclases (DGCs), SadC and SiaD, were responsible for the increased intracellular content of c-di-GMP. Enhanced c-di-GMP levels by TeO3(2-) further...... increased P. aeruginosa biofilm formation and resistance to TeO3(2-). P. aeruginosa ΔsadCΔsiaD and PAO1/p(lac)-yhjH mutants with low intracellular c-di-GMP content were more sensitive to TeO3(2-) exposure and had low relative fitness compared to the wild-type PAO1 planktonic and biofilm cultures exposed...... to TeO3(2-). Our study provided evidence that c-di-GMP level can play an important role in mediating stress response in microbial communities during both planktonic and biofilm modes of growth....

  7. Marine copepod cytochrome P450 genes and their applications for molecular ecotoxicological studies in response to oil pollution.

    Science.gov (United States)

    Han, Jeonghoon; Won, Eun-Ji; Kang, Hye-Min; Lee, Min-Chul; Jeong, Chang-Bum; Kim, Hui-Su; Hwang, Dae-Sik; Lee, Jae-Seong

    2017-11-30

    Recently, accidental spills of heavy oil have caused adverse effects in marine organisms. Oil pollution can induce damages on development and reproduction, linking with detrimental effects on diverse molecular levels of genes and proteins in plankton and fish. However, most information was mainly focused on marine vertebrates and consequently, limited information was available in marine invertebrates. Furthermore, there is still a lack of knowledge bridging in vivo endpoints with the functional regulation of cytochrome P450 (CYP) genes in response to oil spill pollution in marine invertebrates. In this paper, adverse effects of oil spill pollution in marine invertebrates are summarized with the importance of CYP genes as a potential biomarker, applying for environmental monitoring to detect oil spill using marine copepods. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Building bridges across subdisciplines in marine ecology

    Directory of Open Access Journals (Sweden)

    Lawrence R. Pomeroy

    2004-04-01

    Full Text Available Ecology has evolved many subdisciplines whose members do not necessarily communicate regularly through attending the same meetings or reading and publishing in the same journals. As a result, explanations of ecological processes are often limited to a single factor, process, or group of organisms, and this limited approach may fail to provide the best understanding of how communities and ecosystems are assembled and function. Specifically, there is a need to bring together information on the interplay of top-down and bottom-up influences on complete communities consisting of both macroorganisms and microorganisms. A number of examples from the recent literature illustrate the problems encountered in achieving this goal. These include declining fish populations, estuarine eutrophication, the complex origin of a toxic dinoflagellate bloom, and the interactions of microorganisms and macrooorganisms in marine planktonic food webs.

  9. Assessment of Nuclear Power Plant Impact to the Environment: Effect of Sea Water Temperature Increase on Plankton Population

    International Nuclear Information System (INIS)

    Tjahaja, I P; Pujadi; Supriharyono; Aviati, N; Ruswahyun; Busono, H

    1996-01-01

    Research to study the effect of sea water temperature increase on plankton population had been carried out to predict nuclear power plant impact to the environment. Plankton collected from Jepara waters, Muria Peninsula, was grown on growth medium i.e. sea water enriched with silicate fertilizer. Plankton growth was maintained at temperature varied from 34oC to 46oC and the amount of plankton individu was counted twice a day until it was reduced about 95%. The results showed that the reduction of amount of plankton individu occurred on the medium with temperature above the ambient temperature (34oC). The rate of reduction is linear to the temperature increase. There is no plankton survived at temperature above 40oC for more than 24 hours

  10. Sheldon spectrum and the plankton paradox: two sides of the same coin-a trait-based plankton size-spectrum model.

    Science.gov (United States)

    Cuesta, José A; Delius, Gustav W; Law, Richard

    2018-01-01

    The Sheldon spectrum describes a remarkable regularity in aquatic ecosystems: the biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. While size-spectrum models have explained this phenomenon for assemblages of multicellular organisms, this paper introduces a species-resolved size-spectrum model to explain the phenomenon in unicellular plankton. A Sheldon spectrum spanning the cell-size range of unicellular plankton necessarily consists of a large number of coexisting species covering a wide range of characteristic sizes. The coexistence of many phytoplankton species feeding on a small number of resources is known as the Paradox of the Plankton. Our model resolves the paradox by showing that coexistence is facilitated by the allometric scaling of four physiological rates. Two of the allometries have empirical support, the remaining two emerge from predator-prey interactions exactly when the abundances follow a Sheldon spectrum. Our plankton model is a scale-invariant trait-based size-spectrum model: it describes the abundance of phyto- and zooplankton cells as a function of both size and species trait (the maximal size before cell division). It incorporates growth due to resource consumption and predation on smaller cells, death due to predation, and a flexible cell division process. We give analytic solutions at steady state for both the within-species size distributions and the relative abundances across species.

  11. A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments

    International Nuclear Information System (INIS)

    Szefer, P.; Fowler, S.W.; Ikuta, K.; Osuna, F. Paez; Ali, A.A.; Kim, B.-S.; Fernandes, H.M.; Belzunce, M.-J.; Guterstam, B.; Kunzendorf, H.; Wolowicz, M.; Hummel, H.; Deslous-Paoli, M.

    2006-01-01

    Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas. - Byssus of mytilids, like soft tissues can be used as efficient biomonitor for heavy metals in the marine environment

  12. A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments

    Energy Technology Data Exchange (ETDEWEB)

    Szefer, P. [Department of Food Sciences, Medical University of Gdansk, Al. Gen. J. Hallera 107, PL 80-416 Gdansk (Poland)]. E-mail: pszef@amg.gda.pl; Fowler, S.W. [IAEA Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 (Monaco); Ikuta, K. [Laboratory of Aquatic Environment and Ecology, Department of Fisheries, Faculty of Agriculture, Miyazaki University, 889-21 Miyazaki (Japan); Osuna, F. Paez [Institute of Marine Sciences and Limnology, Mazatlan Station, National Autonomous University of Mexico, Mazatlan 82000, Sinaloa (Mexico); Ali, A.A. [Faculty of Science, Arts and Education, University of Aden, PO Box 6014, Khormaksar, Aden (Yemen); Kim, B.-S. [School of Earth and Environmental Science, Seoul National University, 56-1 Shillimdong, 151-742 (Korea, Republic of); Fernandes, H.M. [Instituto de Radioprotecao e Dosimetria, Cz. Postal 37 750 - CEP: 22642-970, Rio de Janeiro (Brazil); Belzunce, M.-J. [Instituto Tecnnologico Pesquero y Alimentario, Dpto de Oceanografia y Medio Ambiente Marino, Herrera Kaia, Portualdea z/g, 20110 Pasaia (Gipuzkoa) (Spain); Guterstam, B. [Stensund Ecological Center, 61991 Trosa, Sweden and Global Water Partnership Secretariat, Hantverkargatan 5, SE-112 21 Stockholm (Sweden); Kunzendorf, H. [Gamma Dating Center (GDC), Institute of Geography, University of Copenhagen, Oster Voldgage 10 DK-1350 Copenhagen K (Denmark); Wolowicz, M. [Laboratory of Estuarine Ecology, Institute of Oceanography, University of Gdansk, Al. Pilsudskiego 46, 81-378, Gdynia (Poland); Hummel, H. [Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology, Korringaweg 7, 4401 NT Yerseke (Netherlands); Deslous-Paoli, M. [IFREMER, Unite Ecologie Conchylicole, 1, rue Jean Vilar, 34200 Sete (France)

    2006-01-15

    Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas. - Byssus of mytilids, like soft tissues can be used as efficient biomonitor for heavy metals in the marine environment.

  13. Comparison of transcriptional heterogeneity of eight genes between batch Desulfovibrio vulgaris biofilm and planktonic culture at a single-cell level

    Directory of Open Access Journals (Sweden)

    Zhenhua eQi

    2016-04-01

    Full Text Available Sulfate-reducing bacteria (SRB biofilm formed on metal surfaces can change the physicochemical properties of metals and cause metal corrosion. To enhance understanding of differential gene expression in Desulfovibrio vulgaris under planktonic and biofilm growth modes, a single-cell based RT-qPCR approach was applied to determine gene expression levels of 8 selected target genes in four sets of the 31 individual cells isolated from each growth condition (i.e., biofilm formed on a stainless steel (SS) and planktonic cultures, exponential and stationary phases. The results showed obvious gene-expression heterogeneity for the target genes among D. vulgaris single cells of both biofilm and planktonic cultures. In addition, an increased gene-expression heterogeneity in the D. vulgaris biofilm when compared with the planktonic culture was also observed for seven out of eight selected genes, which may be contributing to the increased complexity in terms of structures and morphology in the biofilm. Moreover, the results showed up-regulation of DVU0281 gene encoding exopolysaccharide biosynthesis protein, and down-regulation of genes involved in energy metabolism (i.e., DVU0434 and DVU0588, stress responses (i.e., DVU2410 and response regulator (i.e., DVU3062 in the D. vulgaris biofilm cells. Finally, the gene (DVU2571 involved in iron transportation was found down-regulated, and two genes (DVU1340 and DVU1397 involved in ferric uptake repressor and iron storage were up-regulated in D. vulgaris biofilm, suggesting their possible roles in maintaining normal metabolism of the D. vulgaris biofilm under environments of high concentration of iron. This study showed that the single-cell based analysis could be a useful approach in deciphering metabolism of microbial biofilms.

  14. The combination of ultrasound with antibiotics released from bone cement decreases the viability of planktonic and biofilm bacteria: an in vitro study with clinical strains.

    Science.gov (United States)

    Ensing, Geert T; Neut, Daniëlle; van Horn, Jim R; van der Mei, Henny C; Busscher, Henk J

    2006-12-01

    Antibiotic-loaded bone cements are used for the permanent fixation of joint prostheses. Antibiotic-loaded cements significantly decrease the incidence of infection. The objective of this study was to investigate whether the viability of bacteria derived from patients with a prosthesis-related infection could be further decreased when antibiotic release from bone cements was combined with application of pulsed ultrasound. Escherichia coli ATCC 10798, Staphylococcus aureus 7323, coagulase-negative staphylococci (CoNS 7368 and CoNS 7391) and Pseudomonas aeruginosa 5148 were grown planktonically in suspension and as a biofilm on three different bone cements: Palacos R without gentamicin as control, gentamicin-loaded Palacos R-G and gentamicin/clindamycin-loaded Copal. The viability of planktonic and biofilm bacteria was measured in the absence and presence of pulsed ultrasound for 40 h. Ultrasound itself did not affect bacterial viability. However, application of pulsed ultrasound in combination with antibiotic release by antibiotic-loaded bone cements yielded a reduction of both planktonic and biofilm bacterial viability compared with antibiotic release without application of ultrasound. This study shows that antibiotic release in combination with ultrasound increases the antimicrobial efficacy further than antibiotic release alone against a variety of clinical isolates. Application of ultrasound in combination with antibiotic release in clinical practice could therefore lead to better prevention or treatment of prosthesis-related infections.

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

    International Nuclear Information System (INIS)

    Sorrell, Brian K; Safi, Karl; Hawes, Ian

    2013-01-01

    We compared planktonic primary and secondary production across twenty meltwater ponds on the surface of the McMurdo Ice Shelf in January 2007, including some ponds with basal brines created by meromictic stratification. Primary production ranged from 1.07 to 65.72 mgC m −3 h −1 in surface waters. In stratified ponds primary production was always more than ten times higher in basal brines than in the corresponding mixolimnion. Regression tree analysis (r 2 = 0.80) identified inorganic nitrogen (as NH 4 + ) as the main factor limiting planktonic primary production. However, there was also evidence of inorganic carbon co-limitation of photosynthesis in some of the more oligotrophic waters. Neither C nor N limited carbon fixation at [NH 4 –N] > 50 mg m −3 , with photoinhibition the factor most likely limiting photosynthesis under such conditions. Primary production was the only factor significantly correlated to bacterial production and the relationship (r 2 = 0.56) was non-linear. Nitrogen limitation and tight coupling of planktonic primary and bacterial production is surprising in these ponds, as all have large pools of dissolved organic carbon (1.2–260 g m −3 ) and organic nitrogen (all >130 mg m −3 ). The dissolved pools of organic carbon and nitrogen appear to be recalcitrant and bacterial production to be constrained by limited release of labile organics from phytoplankton. (letter)

  16. Plankton community structure and connectivity in the Kimberley-Browse region of NW Australia

    Science.gov (United States)

    McKinnon, A. D.; Duggan, S.; Holliday, D.; Brinkman, R.

    2015-02-01

    We describe the zooplankton and ichthyoplankton communities of coastal waters of the Kimberley coast (North West Australia), sampled in macrotidal Camden Sound during both the wet and dry seasons of 2011, and compare these to six other Kimberley embayments during the wet season of 2013. Zooplankton abundance in Camden Sound was 7038 ± 3913 SD ind. m-3 in the wet season and 1892 ± 708 SD ind. m-3 in the dry season, with copepods accounting for 85% by number. In all, 78 species of copepods were recorded, with the families Paracalanidae and Oithonidae dominant. In Camden Sound, 48 families of larval fish occurred, with ichthyoplankton more abundant in the wet season than the dry season (1.16 ± 0.2 ind. m-3 cf 0.76 ± 0.2 ind. m-3). Larval gobiids (Subfamily Gobiinae) were most abundant, with other common families associated with either pelagic or soft-bottom habitats as adults. Multivariate analyses of both copepod and ichthyoplankton communities demonstrated strong seasonal contrasts, although an along-shelf gradient in copepod community composition was apparent along the embayments sampled in 2013. There was little spatial variation in plankton communities within Camden Sound as a result of the large tidal range (up to 11.7 m, with 2.5 m-1 velocities), although gradients in abundance and composition on cross-shelf transects occurred in the more northern embayments that had a lower tidal range, such as Napier Broome Bay. Copepod communities of the Kimberley-Browse region were placed in regional perspective by multivariate analyses of similar data collected in the eastern Indian Ocean at Scott Reef, in the Arafura Sea and on the southern North West (NW) shelf. The plankton communities of the NW shelf form a series of along-shore metacommunities linked by advection, with weaker cross-shelf connectivity. The presence of the larvae of mesopelagic fishes of the family Myctophidae in coastal waters confirms seasonal cross-shelf connectivity.

  17. Synthetical Analysis for Morphology, biological Species, and stable Isotopes (SAMSI) of single-cell planktonic foraminifer

    Science.gov (United States)

    Ujiie, Y.; Kimoto, K.; Ishimura, T.

    2017-12-01

    Planktonic foraminifers are widely used in the studies of paleontology and paleoceanography, because the morphology of their calcareous shells is enough highly variable to identify the morphospecies and the chemical composition of the shells reflect ambient seawater condition. Although the morphospecies were believed to represent environments associating with latitudinal temperature range of the world ocean, molecular phylogeographic studies have unveiled the presence of multiple biological species in a single morphospecies and their species-specific distributions. This implicates the actual complexity of planktonic foraminiferal ecology. Conversely, these biological species have a high potential for providing novel ecological and environmental information to us. In order to reassess the morphological and geochemical characters of biological species, the DNA extraction method with the guanidium isothiocyanate buffer was developed to preserve the calcareous shells. The present study carefully tested the physical and chemical damages of the DNA extraction process to the shells, by our novel approaches with geochemical analysis of the shells after non-destructive analysis for morphometrics on a same specimen. First, we checked the changes of the shell densities between pre- and post-DNA extraction by using the micro-focus X-ray CT (MXCT) scanning. Based on the simultaneous measurement of a sample and the standard material, we confirmed no significant changes to the shell densities through the DNA extraction process. As a next step, we compared stable oxygen and carbon isotopes among individuals of three sample sets: (1) no chemical and incubation as control, (2) incubation in the DNA extraction buffer at 65-70°C for 40 minutes as standard way, and (3) incubation in the DNA extraction buffer at 65-70°C for 120 minutes, by using the microscale isotopic analytical system (MICAL3c). Consequently, there were no significant differences among the three sample sets. These

  18. The continuous plankton recorder survey: A long-term, basin-scale oceanic time series

    Science.gov (United States)

    Gamble, John C.; Hunt, Harold G.

    1992-01-01

    In the 1920s, before the advent of echo sounders, fishery biologists were greatly concerned with assisting the fisherman to locate schools of pelagic fish. One of the approaches they developed was to relate the distribution of the planktonic food organisms to the presence of the schools of predators such as herring (Clupea harengus). The British planktologist, Alister Hardy, who had already carried out extensive studies on the feeding preferences of herring (Hardy, 1926a), initiated a program to examine the fishermen's contention that herring schools avoided 'green', i.e., phytoplankton-rich, water but could be correlated with high concentrations of zooplankton. This practical program was centered on the use of a specially developed instrument, the 'Plankton Indicator', designed to be used by the fisherman to assist in the search for suitable waters. It had limited success in its main aim but, as a collecting device, it embodied several profoundly important features. It was a simple instrument which was robust enough to be deployed and recovered by the crew of commercial vessels (in this case fishing vessels) while they were underway. The Indicator however, was no more than a high speed net which integrated the plankton over the area of sampling, but Hardy had also become interested in describing the patchiness of planktonic populations. He thus developed the Continuous Plankton Recorder (CPR) where he substituted the fixed filter screen of the Indicator by a continually moving length of silk mesh. The screen traversed at constant speed across the path of the incoming water and the trapped organisms were retained in place by sandwiching beneath an additional second mesh screen. Thus, knowing the speed of the towing vessel and the shooting and hauling positions, the spatial patterns of the plankton could be determined. Hardy took the first CPR to the Antarctic where he used it in the Southern Atlantic (Hardy, 1926b) and later deployed it in the North Sea to make

  19. Activation analysis of several species of marine invertebrates as indicators of environmental conditions

    International Nuclear Information System (INIS)

    Fukushima, M.; Tamate, H.; Nakano, Y.

    2000-01-01

    Marine invertebrates are well known to accumulate trace metals from seawater, plankton, sea plants, and sediments. To test the usefulness of such organisms as a bio-indicator of environmental conditions, we have determined levels of trace elements in tissue of twelve species of marine invertebrates by photon and neutron activation analysis. Relatively higher concentration of elements were observed for Ni and Sn in mid-gut gland, for Cu and Zn in oyster tissues, for Se in swimming crabs, for Cu, Fe, and Se in gills of swimming crabs. Our results indicate that mid-gut gland of ear-shell will be useful as the indicator of environmental conditions. (author)

  20. Extreme warmth and heat-stressed plankton in the tropics during the Paleocene-Eocene Thermal Maximum.

    Science.gov (United States)

    Frieling, Joost; Gebhardt, Holger; Huber, Matthew; Adekeye, Olabisi A; Akande, Samuel O; Reichart, Gert-Jan; Middelburg, Jack J; Schouten, Stefan; Sluijs, Appy

    2017-03-01

    Global ocean temperatures rapidly warmed by ~5°C during the Paleocene-Eocene Thermal Maximum (PETM; ~56 million years ago). Extratropical sea surface temperatures (SSTs) met or exceeded modern subtropical values. With these warm extratropical temperatures, climate models predict tropical SSTs >35°C-near upper physiological temperature limits for many organisms. However, few data are available to test these projected extreme tropical temperatures or their potential lethality. We identify the PETM in a shallow marine sedimentary section deposited in Nigeria. On the basis of planktonic foraminiferal Mg/Ca and oxygen isotope ratios and the molecular proxy [Formula: see text], latest Paleocene equatorial SSTs were ~33°C, and [Formula: see text] indicates that SSTs rose to >36°C during the PETM. This confirms model predictions on the magnitude of polar amplification and refutes the tropical thermostat theory. We attribute a massive drop in dinoflagellate abundance and diversity at peak warmth to thermal stress, showing that the base of tropical food webs is vulnerable to rapid warming.

  1. An integrated fish-plankton aquaculture system in brackish water.

    Science.gov (United States)

    Gilles, S; Fargier, L; Lazzaro, X; Baras, E; De Wilde, N; Drakidès, C; Amiel, C; Rispal, B; Blancheton, J-P

    2013-02-01

    Integrated Multi-Trophic Aquaculture takes advantage of the mutualism between some detritivorous fish and phytoplankton. The fish recycle nutrients by consuming live (and dead) algae and provide the inorganic carbon to fuel the growth of live algae. In the meanwhile, algae purify the water and generate the oxygen required by fishes. Such mechanism stabilizes the functioning of an artificially recycling ecosystem, as exemplified by combining the euryhaline tilapia Sarotherodon melanotheron heudelotii and the unicellular alga Chlorella sp. Feed addition in this ecosystem results in faster fish growth but also in an increase in phytoplankton biomass, which must be limited. In the prototype described here, the algal population control is exerted by herbivorous zooplankton growing in a separate pond connected in parallel to the fish-algae ecosystem. The zooplankton production is then consumed by tilapia, particularly by the fry and juveniles, when water is returned to the main circuit. Chlorella sp. and Brachionus plicatilis are two planktonic species that have spontaneously colonized the brackish water of the prototype, which was set-up in Senegal along the Atlantic Ocean shoreline. In our system, water was entirely recycled and only evaporation was compensated (1.5% volume/day). Sediment, which accumulated in the zooplankton pond, was the only trophic cul-de-sac. The system was temporarily destabilized following an accidental rotifer invasion in the main circuit. This caused Chlorella disappearance and replacement by opportunist algae, not consumed by Brachionus. Following the entire consumption of the Brachionus population by tilapias, Chlorella predominated again. Our artificial ecosystem combining S. m. heudelotii, Chlorella and B. plicatilis thus appeared to be resilient. This farming system was operated over one year with a fish productivity of 1.85 kg/m2 per year during the cold season (January to April).

  2. Extinction, recolonization, and dispersal through time in a planktonic crustacean.

    Science.gov (United States)

    Mergeay, Joachim; Vanoverbeke, Joost; Verschuren, Dirk; De Meester, Luc

    2007-12-01

    Dormant propagule banks are important reservoirs of biological and genetic diversity of local communities and populations and provide buffering mechanisms against extinction. Although dormant stages of various plant and animal species are known to remain viable for decades and even centuries, little is known about the effective influence of recolonization from such old sources on the genetic continuity of intermittent populations under natural conditions. Using recent and old dormant eggs recovered from a dated lake sediment core in Kenya, we traced the genetic composition of a local population of the planktonic crustacean Daphnia barbata through a sequence of extinction and recolonization events. This was combined with a phylogeographic and population-genetic survey of regional populations. Four successive populations, fully separated in time, inhabited Lake Naivasha from ca. 1330 to 1570 AD, from ca. 1610 to 1720 AD, from ca. 1840 to 1940 AD, and from 1995 to the present (2001 AD). Our results strongly indicate genetic continuity between the 1840-1940 and 1995-2001 populations, which are separated in time by at least 50 years, and close genetic relatedness of them both to the 1330-1580 population. A software tool (Colonize) was developed to find the most likely source population of the refounded 1995-2001 population and to test the number of colonists involved in the recolonization event. The results confirmed that the 1995-2001 population most probably developed out of a limited number of surviving local dormant eggs from the previous population, rather than out of individuals from regional (central and southern Kenya) or more distant (Ethiopia, Zimbabwe) populations that may have immigrated to Lake Naivasha through passive dispersal. These results emphasize the importance of prolonged dormancy for the natural long-term dynamics of crustacean zooplankton in fluctuating environments and suggest an important role of old local dormant egg banks in aquatic habitat

  3. Modelling the competition of planktonic and sessile aerobic heterotrophs for complementary nutrients in biofilm reactor.

    Science.gov (United States)

    Lu, T; Saikaly, P E; Oerther, D B

    2007-01-01

    A comprehensive, simplified microbial biofilm model was developed to evaluate the impact of bioreactor operating parameters on changes in microbial population abundance. Biofilm simulations were conducted using three special cases: fully penetrated, internal mass transfer resistance and external mass transfer resistance. The results of model simulations showed that for certain operating conditions, competition for growth limiting nutrients generated oscillations in the abundance of planktonic and sessile microbial populations. These oscillations resulted in the violation of the competitive exclusion principle where the number of microbial populations was greater than the number of growth limiting nutrients. However, the operating conditions which impacted microbial community diversity were different for the three special cases. Comparing the results of model simulations for dispersed-growth, biofilms and bioflocs showed that oscillations and microbial community diversity were a function of competition as well as other key features of the ecosystem. The significance of the current study is that it is the first to examine competition as a mechanism for controlling microbial community diversity in biofilm reactors.

  4. Attached and planktonic Listeria monocytogenes global proteomic responses and associated influence of strain genetics and temperature.

    Science.gov (United States)

    Mata, Marcia M; da Silva, Wladimir P; Wilson, Richard; Lowe, Edwin; Bowman, John P

    2015-02-06

    Contamination of industrial and domestic food usage environments by the attachement of bacterial food-borne pathogen Listeria monocytogenes has public health and economic implications. Comprehensive proteomics experiments using label-free liquid chromatography/tandem mass spectrometry were used to compare the proteomes of two different L. monocytogenes strains (Siliken_1/2c and F2365_4b), which show very different capacities to attach to surfaces. Growth temperature and strain type were highly influential on the proteomes in both attached and planktonic cells. On the basis of the proteomic data, it is highly unlikely that specific surface proteins play a direct role in adherence to inanimate surfaces. Instead, strain-dependent responses related to cell envelope polymer biosynthesis and stress response regulation likely contribute to a different ability to attach and also to survive external stressors. Collectively, the divergent proteome-level responses observed define strain- and growth-temperature-dependent differences relevant to attachment efficacy, highlight relevant proteins involved in stress protection in attached cells, and suggest that strain differences and growth conditions are important in relation to environmental persistence.

  5. Biosorption of nonylphenol by pure algae, field-collected planktons and their fractions

    International Nuclear Information System (INIS)

    Zhang, Dainan; Ran, Yong; Cao, Xiaoyan; Mao, Jingdong; Cui, Jinfang; Schmidt-Rohr, Klaus

    2015-01-01

    Algal samples were fractionated into lipid (LP), lipid free (LF), alkaline nonhydrolyzable carbon (ANHC), and acid nonhydrolyzable carbon (NHC) fractions, and were characterized by the quantitative 13 C multiCP NMR technique. The biosorption isotherms for nonylphenol (NP) were established and compared with previously published data for phenanthrene (Phen). The log K OC values are significantly higher for the field-collected plankton samples than for the commercial algae and cultured algae samples, correlating with their lipid contents and aliphatic carbon structure. As the NHC fraction contains more poly(methylene) carbon, it exhibits a higher biosorption capacity. The sorption capacities are negatively related to the polarity index, COO/N–C=O, polar C and O-alkyl C concentrations, but are positively related to the H/O atomic ratios and poly(methylene) carbon. The higher sorption capacities observed for NP than for Phen on the investigated samples are explained by specific interactions such as hydrogen bonding and π–π interaction. - Highlights: • Quantitative 13 C NMR technique was applied to algae and their fraction samples. • The biosorption isotherms for the ANHC and NHC fractions are nonlinear. • Polarity and lipid affect the biosorption capacity of NP. • The sorption capacity is positively related to polymethylene carbon. • The hydrogen and π–π interactions between NP and algae could be important. - The NHC fractions are chemically and structurally different from other fractions, and their biosorption for NP is much higher than that of the bulk algae

  6. Effects of the global changes on the aquatic ecosystems in West Europe - role of the plankton communities; Effets des changements globaux sur les ecosystemes aquatiques d'Europe Occidentale - role des communautes planctoniques

    Energy Technology Data Exchange (ETDEWEB)

    Souissi, S. [Universite des Sciences et Technologies de Lille, Ecosystem COmplexity REsearch Group, Station Marine de Wimereux, CNRS - FRE 2816 ELICO, 62 - Wimereux (France)

    2007-07-01

    Examination of long-term records of aquatic ecosystems has provided useful information to find out their major driving forces. Understanding the impact of climate change on these ecosystems, the management of their resources and the extrapolation between sites are the main scopes of actual and emerging studies. Such goals can be achieved by inter-site and inter-ecosystem comparisons. This approach was undertaken during our project which has the originality to tackle with marine and freshwater ecosystems. It allowed us to compile and validate several multi-decadal time series of planktonic and other physical driving forces at local and regional scales. Then, the same methodology based on the analysis of the variability of climate indices and biological data across several spatial scales was used. The different ecosystems analyzed here showed clear response to the North Atlantic climate variability. Although the local differences abrupt changes in community composition occurred in all ecosystems in the middle of the years 80. During this period there was also a major shift in climatic conditions during winter and early spring, suggesting an impact of climatic factors. Phenological changes were also observed in plankton communities in all sites. The consequences of the modifications of plankton dynamics on higher trophic levels were also showed. Fluctuations in plankton have resulted in long-term changes in cod recruitment in the North Sea (bottom-up control). On the other hand, both climate change and the improvement of trophic status in Geneva Lake favored the outbreak of whitefish during the years 90. Lower larval mortality and better recruitment are supposed to be linked to faster growth associated with warmer temperatures and better food conditions induced by better temporal overlap between larvae hatching and zooplankton development. (author)

  7. Ecological Significance of Marine Microzooplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Godhantaraman, N.

    ). Studies concerning microzooplankton in marine coastal, estuarine and brackish-water systems along tropical Indian waters are limited. Hence, in the following sections, I provide the results obtained by the research conducted in the tropical Vellar... estuarine systems, southeast coast of India. This was one of the first comprehensive studies on microzooplankton in India. There are also comparative accounts of microzooplankton researches from my studies in Japanese coastal marine waters. Microzooplankton...

  8. TBT toxicity on a natural planktonic assemblage exposed to enhanced ultraviolet-B radiation.

    Science.gov (United States)

    Sargian, Peggy; Pelletier, Emilien; Mostajir, Behzad; Ferreyra, Gustavo A; Demers, Serge

    2005-07-01

    A microcosm approach was designed to study the combined effects of tributyltin (TBT) from antifouling paints and ultraviolet-B radiation (UVBR: 280-320 nm), on a natural planktonic assemblage (TBT (120 ng l -1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBT-added (NUVBR+TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR+TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR+TBT treatment), Chl a concentrations never exceeded 1 microg l-1 whereas final values as high as 54 microg l-1 were observed in TBT-free treatments (NUVBR and HUVBR). TBT addition resulted also in the lost of fluorescence signal of the maximum efficiency of the photosystem II in phytoplankton assemblage. TBT toxicity caused on phytoplankton TBT resulted in a final abundance of phytoplankton TBT relative to NUVBR treatment (i.e., 31,846+/-312 cells ml-1). Moreover, when cells were submitted to TBT under enhanced UVBR (HUVBR+TBT treatment), final abundance of phytoplankton TBT and UVBR during the last 2 days of the experiment. The same type of interaction was also observed for bacterial abundance in NUVBR+TBT and HUVBR+TBT with stimulation of 226 and of 403%, respectively due to TBT addition relative to NUVBR treatment. When considering bacterial productivity, TBT addition resulted in an inhibition of 32%, and this inhibition was significantly more pronounced under dual stresses (i.e., 77% in HUVBR+TBT). These results clearly demonstrate that the combination of TBT and UVBR

  9. TBT toxicity on a natural planktonic assemblage exposed to enhanced ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Sargian, Peggy; Pelletier, Emilien; Mostajir, Behzad; Ferreyra, Gustavo A.; Demers, Serge

    2005-01-01

    A microcosm approach was designed to study the combined effects of tributyltin (TBT) from antifouling paints and ultraviolet-B radiation (UVBR: 280-320 nm), on a natural planktonic assemblage ( -1 ) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR) (ii) NUVBR light condition with TBT-added (NUVBR + TBT) (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR + TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl a concentrations never exceeded 1 μg l -1 whereas final values as high as 54 μg l -1 were observed in TBT-free treatments (NUVBR and HUVBR). TBT addition resulted also in the lost of fluorescence signal of the maximum efficiency of the photosystem II in phytoplankton assemblage. TBT toxicity caused on phytoplankton -1 in NUVBR + TBT relative to NUVBR treatment (i.e., 31,846 ± 312 cells ml -1 ). Moreover, when cells were submitted to TBT under enhanced UVBR (HUVBR + TBT treatment), final abundance of phytoplankton -1 , with a significant interaction between TBT and UVBR during the last 2 days of the experiment. The same type of interaction was also observed for bacterial abundance in NUVBR + TBT and HUVBR + TBT with stimulation of 226 and of 403%, respectively due to TBT addition relative to NUVBR treatment. When considering bacterial productivity, TBT addition resulted in an inhibition of 32%, and this inhibition was significantly more pronounced under dual stresses (i.e., 77% in HUVBR + TBT). These results clearly demonstrate that the combination of TBT

  10. Factors driving the seasonal distribution of planktonic and epiphytic ciliates in a eutrophicated Mediterranean Lagoon

    Energy Technology Data Exchange (ETDEWEB)

    Dhib, Amel [Université de Franche-Comté, Laboratoire de Chrono-Environnement, UMR CNRS 6249 (France); Institut National des Sciences et Technologies de la Mer (INSTM), Laboratoire Milieu Marin, Centre la Goulette (Tunisia); Brahim, Mounir Ben; Ziadi, Boutheina; Akrout, Fourat; Turki, Souad [Institut National des Sciences et Technologies de la Mer (INSTM), Laboratoire Milieu Marin, Centre la Goulette (Tunisia); Aleya, Lotfi [Université de Franche-Comté, Laboratoire de Chrono-Environnement, UMR CNRS 6249 (France)

    2013-09-15

    Highlights: • Distribution of planktonic and epiphytic ciliates at five stations in Ghar El Melh Lagoon. • 28 planktonic ciliates were identified with spring-early autumn peaks. • 4 epiphytic ciliates of the seagrass Ruppia cirrhosa were recorded with high density. • Significant correlations were found between ciliate assemblages, environmental factors and harmful dinoflagellates. -- Abstract: We studied the distribution of planktonic and epiphytic ciliates coupled with environmental factors and microalgae abundance at five stations in Ghar El Melh Lagoon (Tunisia). Planktonic ciliates were monitored for a year and epiphytic ciliates were sampled during summer 2011 in concordance with the proliferation of the seagrass Ruppia cirrhosa. Ciliate assemblage was largely dominated by Spirotrichea followed respectively by Tintinnida of and Strombidiida. No significant difference was found in the distribution of ciliate species among the stations. Redundancy analysis indicates that abiotic factors (temperature and nutriments) have a significant effect on the dynamics of certain ciliates. For epiphytic ciliates, 4 species were identified: Tintinnopsis campanula, Aspidisca sp., Strombidium acutum and Amphorides amphora. Based on PERMANOVA analyses, ciliates exhibit significant correlations among months and stations. According to ACP, epiphyte distribution follows roughly those of R. cirrhosa and pH. Significant correlations were found between harmful dinoflagellates and both planktonic and epiphytic ciliates.

  11. Factors driving the seasonal distribution of planktonic and epiphytic ciliates in a eutrophicated Mediterranean Lagoon

    International Nuclear Information System (INIS)

    Dhib, Amel; Brahim, Mounir Ben; Ziadi, Boutheina; Akrout, Fourat; Turki, Souad; Aleya, Lotfi

    2013-01-01

    Highlights: • Distribution of planktonic and epiphytic ciliates at five stations in Ghar El Melh Lagoon. • 28 planktonic ciliates were identified with spring-early autumn peaks. • 4 epiphytic ciliates of the seagrass Ruppia cirrhosa were recorded with high density. • Significant correlations were found between ciliate assemblages, environmental factors and harmful dinoflagellates. -- Abstract: We studied the distribution of planktonic and epiphytic ciliates coupled with environmental factors and microalgae abundance at five stations in Ghar El Melh Lagoon (Tunisia). Planktonic ciliates were monitored for a year and epiphytic ciliates were sampled during summer 2011 in concordance with the proliferation of the seagrass Ruppia cirrhosa. Ciliate assemblage was largely dominated by Spirotrichea followed respectively by Tintinnida of and Strombidiida. No significant difference was found in the distribution of ciliate species among the stations. Redundancy analysis indicates that abiotic factors (temperature and nutriments) have a significant effect on the dynamics of certain ciliates. For epiphytic ciliates, 4 species were identified: Tintinnopsis campanula, Aspidisca sp., Strombidium acutum and Amphorides amphora. Based on PERMANOVA analyses, ciliates exhibit significant correlations among months and stations. According to ACP, epiphyte distribution follows roughly those of R. cirrhosa and pH. Significant correlations were found between harmful dinoflagellates and both planktonic and epiphytic ciliates

  12. Norwegian deep-water coral reefs: cultivation and molecular analysis of planktonic microbial communities.

    Science.gov (United States)

    Jensen, Sigmund; Lynch, Michael D J; Ray, Jessica L; Neufeld, Josh D; Hovland, Martin

    2015-10-01

    Deep-sea coral reefs do not receive sunlight and depend on plankton. Little is known about the plankton composition at such reefs, even though they constitute habitats for many invertebrates and fish. We investigated plankton communities from three reefs at 260-350 m depth at hydrocarbon fields off the mid-Norwegian coast using a combination of cultivation and small subunit (SSU) rRNA gene and transcript sequencing. Eight months incubations of a reef water sample with minimal medium, supplemented with carbon dioxide and gaseous alkanes at in situ-like conditions, enabled isolation of mostly Alphaproteobacteria (Sulfitobacter, Loktanella), Gammaproteobacteria (Colwellia) and Flavobacteria (Polaribacter). The relative abundance of isolates in the original sample ranged from ∼ 0.01% to 0.80%. Comparisons of bacterial SSU sequences from filtered plankton of reef and non-reef control samples indicated high abundance and metabolic activity of primarily Alphaproteobacteria (SAR11 Ia), Gammaproteobacteria (ARCTIC96BD-19), but also of Deltaproteobacteria (Nitrospina, SAR324). Eukaryote SSU sequences indicated metabolically active microalgae and animals, including codfish, at the reef sites. The plankton community composition varied between reefs and differed between DNA and RNA assessments. Over 5000 operational taxonomic units were detected, some indicators of reef sites (e.g. Flavobacteria, Cercozoa, Demospongiae) and some more active at reef sites (e.g. Gammaproteobacteria, Ciliophora, Copepoda). © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Surface ocean metabarcoding confirms limited diversity in planktonic foraminifera but reveals unknown hyper-abundant lineages.

    Science.gov (United States)

    Morard, Raphaël; Garet-Delmas, Marie-José; Mahé, Frédéric; Romac, Sarah; Poulain, Julie; Kucera, Michal; de Vargas, Colomban

    2018-02-07

    Since the advent of DNA metabarcoding surveys, the planktonic realm is considered a treasure trove of diversity, inhabited by a small number of abundant taxa, and a hugely diverse and taxonomically uncharacterized consortium of rare species. Here we assess if the apparent underestimation of plankton diversity applies universally. We target planktonic foraminifera, a group of protists whose known morphological diversity is limited, taxonomically resolved and linked to ribosomal DNA barcodes. We generated a pyrosequencing dataset of ~100,000 partial 18S rRNA foraminiferal sequences from 32 size fractioned photic-zone plankton samples collected at 8 stations in the Indian and Atlantic Oceans during the Tara Oceans expedition (2009-2012). We identified 69 genetic types belonging to 41 morphotaxa in our metabarcoding dataset. The diversity saturated at local and regional scale as well as in the three size fractions and the two depths sampled indicating that the diversity of foraminifera is modest and finite. The large majority of the newly discovered lineages occur in the small size fraction, neglected by classical taxonomy. These unknown lineages dominate the bulk [>0.8 µm] size fraction, implying that a considerable part of the planktonic foraminifera community biomass has its origin in unknown lineages.

  14. Changes in Microbial Plankton Assemblages Induced by Mesoscale Oceanographic Features in the Northern Gulf of Mexico.

    Directory of Open Access Journals (Sweden)

    Alicia K Williams

    Full Text Available Mesoscale circulation generated by the Loop Current in the Northern Gulf of Mexico (NGOM delivers growth-limiting nutrients to the microbial plankton of the euphotic zone. Consequences of physicochemically driven community shifts on higher order consumers and subsequent impacts on the biological carbon pump remain poorly understood. This study evaluates microbial plankton <10 μm abundance and community structure across both cyclonic and anti-cyclonic circulation features in the NGOM using flow cytometry (SYBR Green I and autofluorescence parameters. Non-parametric multivariate hierarchical cluster analyses indicated that significant spatial variability in community structure exists such that stations that clustered together were defined as having a specific 'microbial signature' (i.e. statistically homogeneous community structure profiles based on relative abundance of microbial groups. Salinity and a combination of sea surface height anomaly and sea surface temperature were determined by distance based linear modeling to be abiotic predictor variables significantly correlated to changes in microbial signatures. Correlations between increased microbial abundance and availability of nitrogen suggest nitrogen-limitation of microbial plankton in this open ocean area. Regions of combined coastal water entrainment and mesoscale convergence corresponded to increased heterotrophic prokaryote abundance relative to autotrophic plankton. The results provide an initial assessment of how mesoscale circulation potentially influences microbial plankton abundance and community structure in the NGOM.

  15. Evaluation of the Effects of Photodynamic Therapy Alone and Combined with Standard Antifungal Therapy on Planktonic Cells and Biofilms of Fusarium spp. and Exophiala spp.

    Science.gov (United States)

    Gao, Lujuan; Jiang, Shaojie; Sun, Yi; Deng, Meiqi; Wu, Qingzhi; Li, Ming; Zeng, Tongxiang

    2016-01-01

    Infections of Fusarium spp. and Exophiala spp. are often chronic, recalcitrant, resulting in significant morbidity, causing discomfort, disfigurement, social isolation. Systemic disseminations happen in compromised patients, which are often refractory to available antifungal therapies and thereby lead to death. The antimicrobial photodynamic therapy (aPDT) has been demonstrated to effectively inactivate multiple pathogenic fungi and is considered as a promising alternative treatment for mycoses. In the present study, we applied methylene blue (8, 16, and 32 μg/ml) as a photosensitizing agent and light emitting diode (635 ± 10 nm, 12 and 24 J/cm(2)), and evaluated the effects of photodynamic inactivation on five strains of Fusarium spp. and five strains of Exophiala spp., as well as photodynamic effects on in vitro susceptibility to itraconazole, voriconazole, posaconazole and amphotericin B, both planktonic and biofilm forms. Photodynamic therapy was efficient in reducing the growth of all strains tested, exhibiting colony forming unit-reductions of up to 6.4 log10 and 5.6 log10 against planktonic cultures and biofilms, respectively. However, biofilms were less sensitive since the irradiation time was twice longer than that of planktonic cultures. Notably, the photodynamic effects against Fusarium strains with high minimal inhibitory concentration (MIC) values of ≥16, 4-8, 4-8, and 2-4 μg/ml for itraconazole, voriconazole, posaconazole and amphotericin B, respectively, were comparable or even superior to Exophiala spp., despite Exophiala spp. showed relatively better antifungal susceptibility profile. MIC ranges against planktonic cells of both species were up to 64 times lower after aPDT treatment. Biofilms of both species showed high sessile MIC50 (SMIC50) and SMIC80 of ≥16 μg/ml for all azoles tested and variable susceptibilities to amphotericin B, with SMIC ranging between 1 and 16 μg/ml. Biofilms subjected to aPDT exhibited a distinct reduction in

  16. Marine ecoregion and Deepwater Horizon oil spill affect recruitment and population structure of a salt marsh snail

    Science.gov (United States)

    Pennings, Steven C.; Zengel, Scott; Oehrig, Jacob; Alber, Merryl; Bishop, T. Dale; Deis, Donald R.; Devlin, Donna; Hughes, A. Randall; Hutchens, John J.; Kiehn, Whitney M.; McFarlin, Caroline R.; Montague, Clay L.; Powers, Sean P.; Proffitt, C. Edward; Rutherford, Nicolle; Stagg, Camille L.; Walters, Keith

    2016-01-01

    Marine species with planktonic larvae often have high spatial and temporal variation in recruitment that leads to subsequent variation in the ecology of benthic adults. Using a combination of published and unpublished data, we compared the population structure of the salt marsh snail, Littoraria irrorata, between the South Atlantic Bight and the Gulf Coast of the United States to infer geographic differences in recruitment and to test the hypothesis that the Deepwater Horizon oil spill led to widespread recruitment failure of L. irrorata in Louisiana in 2010. Size-frequency distributions in both ecoregions were bimodal, with troughs in the distributions consistent with a transition from sub-adults to adults at ~13 mm in shell length as reported in the literature; however, adult snails reached larger sizes in the Gulf Coast. The ratio of sub-adults to adults was 1.5–2 times greater in the South Atlantic Bight than the Gulf Coast, consistent with higher recruitment rates in the South Atlantic Bight. Higher recruitment rates in the South Atlantic Bight could contribute to higher snail densities and reduced adult growth in this region. The ratio of sub-adults to adults in Louisiana was lower in 2011 than in previous years, and began to recover in 2012–2014, consistent with widespread recruitment failure in 2010, when large expanses of spilled oil were present in coastal waters. Our results reveal an important difference in the ecology of a key salt marsh invertebrate between the two ecoregions, and also suggest that the Deepwater Horizon oil spill may have caused widespread recruitment failure in this species and perhaps others with similar planktonic larval stages.

  17. Marine Fish Hybridization

    KAUST Repository

    He, Song

    2017-04-01

    Natural hybridization is reproduction (without artificial influence) between two or more species/populations which are distinguishable from each other by heritable characters. Natural hybridizations among marine fishes were highly underappreciated due to limited research effort; it seems that this phenomenon occurs more often than is commonly recognized. As hybridization plays an important role in biodiversity processes in the marine environment, detecting hybridization events and investigating hybridization is important to understand and protect biodiversity. The first chapter sets the framework for this disseration study. The Cohesion Species Concept was selected as the working definition of a species for this study as it can handle marine fish hybridization events. The concept does not require restrictive species boundaries. A general history and background of natural hybridization in marine fishes is reviewed during in chapter as well. Four marine fish hybridization cases were examed and documented in Chapters 2 to 5. In each case study, at least one diagnostic nuclear marker, screened from among ~14 candidate markers, was found to discriminate the putative hybridizing parent species. To further investigate genetic evidence to support the hybrid status for each hybrid offspring in each case, haploweb analysis on diagnostic markers (nuclear and/or mitochondrial) and the DAPC/PCA analysis on microsatellite data were used. By combining the genetic evidences, morphological traits, and ecological observations together, the potential reasons that triggered each hybridization events and the potential genetic/ecology effects could be discussed. In the last chapter, sequences from 82 pairs of hybridizing parents species (for which COI barcoding sequences were available either on GenBank or in our lab) were collected. By comparing the COI fragment p-distance between each hybridizing parent species, some general questions about marine fish hybridization were discussed: Is

  18. Active Marine Station Metadata

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Active Marine Station Metadata is a daily metadata report for active marine bouy and C-MAN (Coastal Marine Automated Network) platforms from the National Data...

  19. Exposure factors for marine eutrophication impacts assessment based on a mechanistic biological model

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Koski, Marja; Hauschild, Michael Zwicky

    2015-01-01

    marine ecosystem (LME), five climate zones, and site-generic. The XFs obtained range from 0.45 (Central Arctic Ocean) to 15.9kgO2kgN-1 (Baltic Sea). While LME resolution is recommended, aggregated PE or XF per climate zone can be adopted, but not global aggregation due to high variability. The XF......Emissions of nitrogen (N) from anthropogenic sources enrich marine waters and promote planktonic growth. This newly synthesised organic carbon is eventually exported to benthic waters where aerobic respiration by heterotrophic bacteria results in the consumption of dissolved oxygen (DO......). This pathway is typical of marine eutrophication. A model is proposed to mechanistically estimate the response of coastal marine ecosystems to N inputs. It addresses the biological processes of nutrient-limited primary production (PP), metazoan consumption, and bacterial degradation, in four distinct sinking...

  20. Marine and estuarine natural microbial biofilms: ecological and biogeochemical dimensions

    Directory of Open Access Journals (Sweden)

    O. Roger Anderson

    2016-08-01

    Full Text Available Marine and estuarine microbial biofilms are ubiquitously distributed worldwide and are increasingly of interest in basic and applied sciences because of their unique structural and functional features that make them remarkably different from the biota in the plankton. This is a review of some current scientific knowledge of naturally occurring microbial marine and estuarine biofilms including prokaryotic and microeukaryotic biota, but excluding research specifically on engineering and applied aspects of biofilms such as biofouling. Because the microbial communities including bacteria and protists are integral to the fundamental ecological and biogeochemical processes that support biofilm communities, particular attention is given to the structural and ecological aspects of microbial biofilm formation, succession, and maturation, as well as the dynamics of the interactions of the microbiota in biofilms. The intent is to highlight current state of scientific knowledge and possible avenues of future productive research, especially focusing on the ecological and biogeochemical dimensions.