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Sample records for zooplankton vertical migration

  1. Twilight vertical migrations of zooplankton in a Chilean fjord

    Science.gov (United States)

    Valle-Levinson, Arnoldo; Castro, Leonardo; Cáceres, Mario; Pizarro, Oscar

    2014-12-01

    Time series of acoustic backscatter and vertical velocity profiles were obtained at three sites along a Chilean fjord with the purpose of determining dominant structures of vertical migrations of the sound scattering layer. Ancillary data obtained with stratified net samples indicated that the sound scattering layer may have been dominated by euphausiids and decapods. Therefore, distributions of acoustic backscatter anomalies and vertical velocities were attributed to vertical migrations of predominantly these organisms. Migration patterns were dominated by twilight excursions in which organisms swam toward the water surface at sunset, spent 100 m). This migration strategy can also be termed 'semidiel migration' as two double excursions were linked to light levels. The reasons for this twilight migration remain uncertain. But it is possible that the up and down motion around sunset was related to predation avoidance, hunger-satiation state, ontogeny, seaward transport evasion, or reaction to the environmental shock from the pycnocline, or a combination of all or some of them. In contrast, the sunrise double excursion was probably linked to feeding requirements by organisms that need to spend the day at great depth with no food available. This study demonstrated the existence of semidiel patterns throughout the fjord and through prolonged periods. In addition, identification of this pattern by acoustic backscatter was complemented by direct vertical velocity measurements. It is proposed that twilight vertical migration is a common strategy in Chilean fjords.

  2. The effects of diel vertical migration of Daphnia on zooplankton-phytoplankton interactions

    OpenAIRE

    Reichwaldt, Elke S.

    2004-01-01

    Zooplankton populations which perform diel vertical migration (DVM) only spend the night in surface water layers but migrate downwards into the lower water layers during the day. The intention of this study was to investigate effects of DVM of Daphnia on phytoplankton dynamics and Daphnia life history parameters in a lake. I conducted field and laboratory experiments in which I compared ‘migration’ with ‘no-migration’ situations. It is generally assumed that phytoplankton communities in the e...

  3. Diel vertical migration and distribution of zooplankton in a tropical Brazilian reservoir

    Directory of Open Access Journals (Sweden)

    Ana M. A. da Silva

    2009-03-01

    Full Text Available Diel vertical migration of zooplankton is a strategy usually employed to reduce the risk of predation, and it can also be associated with the environmental day/night shifts, particularly of light and temperature. The aim of this study was to identify the diel patterns of zooplankton vertical migration and their relationship to the environmental variables in a shallow reservoir in northeastern Brazil. Water samples were taken at a single five-meter depth sampling station (Subsurface, 50% Io, 1% Io and Bottom at four-hour intervals over a period of 24 hours. Two Cladocera species (Moina minuta and Diaphanosoma spinulosum and one Copepoda species (Notodiaptomus cearensis showed similar patterns of nocturnal migration, staying at the bottom during the day and rising toward the surface in the afternoon and during the night. Brachionus falcatus and Hexarthra mira (Rotifera showed no patterns of vertical migration and their vertical distributions were relatively homogenous. Environmental variables were poorly correlated to the species distribution, suggesting that other mechanisms may be responsible of inducing vertical migration.

  4. Zooplankton diel vertical migration and contribution to deep active carbon flux in the NW Mediterranean

    Science.gov (United States)

    Isla, Alejandro; Scharek, Renate; Latasa, Mikel

    2015-03-01

    The diel vertical migration (DVM) of zooplankton contributes to the biological pump transporting material from surface to deep waters. We examined the DVM of the zooplankton community in different size fractions (53-200 ?m, 200-500 ?m, 500-1000 ?m, 1000-2000 ?m and > 2000 ?m) during three cruises carried out in the open NW Mediterranean Sea. We assessed their metabolic rates from empirical published relationships and estimated the active fluxes of dissolved carbon to the mesopelagic zone driven by migrant zooplankton. Within the predominantly oligotrophic Mediterranean Sea, the NW region is one of the most productive ones, with a seasonal cycle characterized by a prominent spring bloom. The study area was visited at three different phases of the seasonal cycle: during the spring bloom, the post-bloom, and strongly stratified oligotrophic conditions. We found seasonal differences in DVM, less evident during the bloom. Changes in DVM intensity were related to the composition of the zooplanktonic assemblage, which also varied between cruises. Euphausiids appeared as the most active migrants in all seasons, and their life cycle conditioned the observed pattern. Immature stages, which are unable to perform large diel vertical movements, dominated during the bloom, in contrast to the higher relative importance of migrating adults in the other two sampling periods. The amount of dissolved carbon exported was determined by the migrant zooplankton biomass, being highest during the post-bloom (2.2 mmol C respired m- 2 d- 1, and up to 3.1 mmol C exported m- 2 d- 1 when DOC release estimations are added). The active transport by diel migrants represented a substantial contribution to total carbon export to deep waters, especially under stratified oligotrophic conditions, revealing the importance of zooplankton in the biological pump operating in the study area.

  5. Zooplankton grazing in a eutrophic lake: implications of diel vertical migration

    International Nuclear Information System (INIS)

    During summer and fall, depth profiles of zooplankton community grazing were determined in situ during day and night in the Schoehsee, a small eutrophic lake. Labeled algae of two different sizes were mixed with the natural suspension of phytoplankton in a grazing chamber. A small blue-green alga (Synechococcus, 1 ?m) was labeled with 32P; a larger green alga (Scenedesmus, 4-15 ?m) was labeled with 14C. During summer, grazing in the upper 5 m was negligible during day but strong at night. Hence, algae grow relatively unimpeded by grazing during daytime but are harvested at night. Vertical and diel differences in grazing rates disappeared when the vertical migration ceased in fall. Selectivity of grazing was controlled by the zooplankton species composition. Eudiaptomus showed a strong preference for Scenedesmus. Daphnia showed a slight preference for Scenedesmus, but Ceriodaphnia preferred Synechococcus. Cyclopoid copepodites did not ingest the small blue-green. Because Daphnia and Eudiaptomus were dominant, grazing rates on larger cells were usually higher than grazing rates on the small cells. Negative electivity indices for scenedesmus occurred only when the biomass of large crustaceans was extremely low (near the surface, during day). Zooplankton biomass was the main factor controlling both vertical and seasonal variations in grazing. Highest grazing rates (65%/d) were measured during fall when zooplankton abundance was high. Because differential losses can produce substantial errors in the results, it was necessary to process the samples on the boat immediately after collection, without preservation

  6. Tidal influence on the diel vertical migration pattern of zooplankton in a tropical monsoonal Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Vineetha, G.; Jyothibabu, R.; Madhu, N.V.; Kusum, K.K.; Sooria, P.M.; Shivaprasad, A.; Reny, P.D.; Deepak, M.P.

    habitats is often determined by their dominant behavioral patterns: diel vertical migration (DVM) and tidal vertical migration (TVM). The modes of these endogenous rhythms often vary among estuaries based on the river runoff and tidal characteristics...

  7. Diel vertical migration patterns of three zooplankton populations in a Chilean lake Patrones de migración vertical de tres poblaciones de zooplancton en un lago chileno

    Directory of Open Access Journals (Sweden)

    RODRIGO RAMOS-JILIBERTO

    2004-03-01

    Full Text Available In this work we analyzed the depth-distribution, at noon and midnight, of three zooplankton populations which are common inhabitants of lakes from central Chile and coexist in lake El Plateado. The species were Tumeodiaptomus diabolicus, Diaphanosoma chilense and Bosmina longirostris. Also, we analyzed the association between the depth-specific abundances of the groups and the depth-specific temperature and oxygen values during the sampling period. Our results show that: (1 the three population exhibited diel vertical migration during part of the year; (2 T. diabolicus and D. chilense exhibited the normal pattern of vertical migration, and B. longirostris presented both the normal and the reverse pattern; (3 for all species and most dates, zooplankters experience significant decreases in oxygen exposure as a consequence of downward migration. Temperature costs are less important but present in T. diabolicus and D. chilense during part of the yearEn este trabajo analizamos la distribución en profundidad, a mediodía y medianoche, de tres poblaciones de zooplancton que son habitantes comunes de los lagos de Chile central, y que coexisten en el lago El Plateado. Las especies fueron Tumeodiaptomus diabolicus, Diaphanosoma chilense y Bosmina longirostris. También analizamos la asociación entre las abundancias profundidad-específicas de los grupos y los valores profundidad-específicos de temperatura y oxígeno durante el periodo de muestreo. Nuestros resultados muestran que: (1 las tres poblaciones exhibieron migración vertical durante una parte del año; (2 T. diabolicus y D. chilense exhibieron el patrón normal de migración, y B. longirostris presentó tanto el patrón normal como el inverso; (3 para todas las especies y en la mayoría de las fechas, el zooplancton presentó reducciones significativas en su exposición al oxígeno como consecuencia de la migración descendente. Los costos térmicos son menos importantes pero existentes en T. diabolicus y D. chilense durante parte del año

  8. Diel vertical migration patterns of three zooplankton populations in a Chilean lake / Patrones de migración vertical de tres poblaciones de zooplancton en un lago chileno

    Scientific Electronic Library Online (English)

    RODRIGO, RAMOS-JILIBERTO; JOSÉ L., CARVAJAL; MAURICIO, CARTER; LUIS R., ZÚÑIGA.

    2004-03-01

    Full Text Available En este trabajo analizamos la distribución en profundidad, a mediodía y medianoche, de tres poblaciones de zooplancton que son habitantes comunes de los lagos de Chile central, y que coexisten en el lago El Plateado. Las especies fueron Tumeodiaptomus diabolicus, Diaphanosoma chilense y Bosmina long [...] irostris. También analizamos la asociación entre las abundancias profundidad-específicas de los grupos y los valores profundidad-específicos de temperatura y oxígeno durante el periodo de muestreo. Nuestros resultados muestran que: (1) las tres poblaciones exhibieron migración vertical durante una parte del año; (2) T. diabolicus y D. chilense exhibieron el patrón normal de migración, y B. longirostris presentó tanto el patrón normal como el inverso; (3) para todas las especies y en la mayoría de las fechas, el zooplancton presentó reducciones significativas en su exposición al oxígeno como consecuencia de la migración descendente. Los costos térmicos son menos importantes pero existentes en T. diabolicus y D. chilense durante parte del año Abstract in english In this work we analyzed the depth-distribution, at noon and midnight, of three zooplankton populations which are common inhabitants of lakes from central Chile and coexist in lake El Plateado. The species were Tumeodiaptomus diabolicus, Diaphanosoma chilense and Bosmina longirostris. Also, we analy [...] zed the association between the depth-specific abundances of the groups and the depth-specific temperature and oxygen values during the sampling period. Our results show that: (1) the three population exhibited diel vertical migration during part of the year; (2) T. diabolicus and D. chilense exhibited the normal pattern of vertical migration, and B. longirostris presented both the normal and the reverse pattern; (3) for all species and most dates, zooplankters experience significant decreases in oxygen exposure as a consequence of downward migration. Temperature costs are less important but present in T. diabolicus and D. chilense during part of the year

  9. Diel vertical migration and spatial overlap between fish larvae and zooplankton in two tropical lakes, Brazil / Migração vertical diária e sobreposição espacial entre larvas de peixes e zooplâncton em dois lagos tropicais, Brasil

    Scientific Electronic Library Online (English)

    PHS., Picapedra; FA., Lansac-Tôha; A., Bialetzki.

    2015-05-01

    Full Text Available O efeito de larvas de peixes sobre a distribuição vertical dia-noite da comunidade zooplanctônica foi investigada em duas lagoas tropicais, lagoa Finado Raimundo e Pintado, Mato Grosso do Sul, Brasil. Foram realizadas amostragens noturnas e diurnas na região limnética de cada lagoa durante um períod [...] o de 10 meses consecutivos, entre abril de 2008 a janeiro de 2009. A comunidade zooplanctônica apresentou uma variada gama de respostas à pressão de predação exercida pelas larvas de peixes nos dois ambientes, enquanto que as larvas de peixes exibiram um padrão típico de migração vertical diária normal. Os resultados mostraram ainda, que a migração vertical diária é um comportamento importante para evitar a predação, uma vez que diminuiu a sobreposição espacial entre presa e seu predador em potencial, dando suporte a hipótese de que a migração vertical é um mecanismo de defesa contra a predação. Abstract in english The effect of fish larvae on the diel vertical migration of the zooplankton community was investigated in two tropical lakes, Finado Raimundo and Pintado lakes, Mato Grosso do Sul State, Brazil. Nocturnal and diurnal samplings were conducted in the limnetic region of each lake for 10 consecutive mon [...] ths from April 2008 to January 2009. The zooplankton community presented a wide range of responses to the predation pressure exerted by fish larvae in both environments, while fish larvae showed a typical pattern of normal diel vertical migration. Our results also demonstrated that the diel vertical migration is an important behaviour to avoid predation, since it reduces the spatial overlap between prey and potential predator, thus supporting the hypothesis that vertical migration is a defence mechanism against predation.

  10. Efecto de la zona de mínimo oxígeno sobre la migración vertical de zooplancton gelatinoso en la bahía de Mejillones The effect of the oxygen minimum zone on vertical migration of gelatinous zooplankton in Mejillones Bay

    Directory of Open Access Journals (Sweden)

    Pedro Apablaza

    2006-11-01

    Full Text Available Se analizó la distribución estacional y migración vertical de zooplancton gelatinoso colectado en la bahía de Mejillones. Se identificaron 39 especies distribuidas en 14 de hidromedusas, 20 de sifonóforos y 5 de quetognatos. Las especies dominantes fueron Obelia spp., Liriope tetraphylla, Solmundella bitentaculata, Rophalonema velatum, Muggiaea atlantica, Sphaeronectes gracilis, Sagitta enfiata y S. bierii, las que presentaron un estrecho rango de distribución vertical y migración nictimeral, debido a la infiuencia de la Zona de Mínimo Oxígeno (ZMO (The seasonal distribution and vertical migration of gelatinous zooplankton collected in Mejillones Bay was analyzed. The 39 species identified included 14 hydromedusae, 20 siphonophores, and 5 chaetognates. The dominant species were Obelia spp., Liriope tetraphylla, Solmundella bitentaculata, Rophalonema velatum, Muggiaea atlantica, Sphaeronectes gracilis, Sagitta enfiata, and S. bierii. Their vertical distribution and nictimeral migration ranges were narrow due to the infiuence of the Oxygen Minimum Zone (OMZ (< 1 mL·L-1, whose upper limit was quite shallow (25-50 m. In spring, the majority of the dominant species presented nictimeral movements due to the greater oxygenation of the water column. On the other hand, in summer, when the thermocline was more intense, and in winter, when the OMZ neared the surface, the majority of the dominant species showed no changes in their vertical distribution throughout the daily cycle. Obelia spp. had a shallow distribution, related principally to the presence of the thermocline. R. velatum, however, was well adapted to the scant dissolved oxygen in the OMZ

  11. Diel vertical migration patterns of three zooplankton populations in a Chilean lake Patrones de migración vertical de tres poblaciones de zooplancton en un lago chileno

    OpenAIRE

    RODRIGO RAMOS-JILIBERTO; JOSÉ L. CARVAJAL; MAURICIO CARTER; LUIS R. ZÚÑIGA

    2004-01-01

    In this work we analyzed the depth-distribution, at noon and midnight, of three zooplankton populations which are common inhabitants of lakes from central Chile and coexist in lake El Plateado. The species were Tumeodiaptomus diabolicus, Diaphanosoma chilense and Bosmina longirostris. Also, we analyzed the association between the depth-specific abundances of the groups and the depth-specific temperature and oxygen values during the sampling period. Our results show that: (1) the three populat...

  12. Trophic ecology and vertical patterns of carbon and nitrogen stable isotopes in zooplankton from oxygen minimum zone regions

    Science.gov (United States)

    Williams, Rebecca L.; Wakeham, Stuart; McKinney, Rick; Wishner, Karen F.

    2014-08-01

    The unique physical and biogeochemical characteristics of oxygen minimum zones (OMZs) influence plankton ecology, including zooplankton trophic webs. Using carbon and nitrogen stable isotopes, this study examined zooplankton trophic webs in the Eastern Tropical North Pacific (ETNP) OMZ. ?13C values were used to indicate zooplankton food sources, and ?15N values were used to indicate zooplankton trophic position and nitrogen cycle pathways. Vertically stratified MOCNESS net tows collected zooplankton from 0 to 1000 m at two stations along a north-south transect in the ETNP during 2007 and 2008, the Tehuantepec Bowl and the Costa Rica Dome. Zooplankton samples were separated into four size fractions for stable isotope analyses. Particulate organic matter (POM), assumed to represent a primary food source for zooplankton, was collected with McLane large volume in situ pumps. The isotopic composition and trophic ecology of the ETNP zooplankton community had distinct spatial and vertical patterns influenced by OMZ structure. The most pronounced vertical isotope gradients occurred near the upper and lower OMZ oxyclines. Material with lower ?13C values was apparently produced in the upper oxycline, possibly by chemoautotrophic microbes, and was subsequently consumed by zooplankton. Between-station differences in ?15N values suggested that different nitrogen cycle processes were dominant at the two locations, which influenced the isotopic characteristics of the zooplankton community. A strong depth gradient in zooplankton ?15N values in the lower oxycline suggested an increase in trophic cycling just below the core of the OMZ. Shallow POM (0-110 m) was likely the most important food source for mixed layer, upper oxycline, and OMZ core zooplankton, while deep POM was an important food source for most lower oxycline zooplankton (except for samples dominated by the seasonally migrating copepod Eucalanus inermis). There was no consistent isotopic progression among the four zooplankton size classes for these bulk mixed assemblage samples, implying overlapping trophic webs within the total size range considered.

  13. Plankton vertical migrations - Implications for the pelagic ecosystem

    OpenAIRE

    Haupt, Florian

    2011-01-01

    Habitat selection is an important behavior of many organisms. The direction and strength of this behavior is often characterized as a result of a trade off between predator avoidance and obtaining resources. A characteristic example of this trade off may be seen in organisms in the pelagic ecosystem in the form of vertical migrations. Diel vertical migration (DVM) is a predator avoidance behavior of many zooplankton species, which is marked by a significant shift in the vertical distribution ...

  14. Vertical distribution of zooplankton: density dependence and evidence for an ideal free distribution with costs

    Directory of Open Access Journals (Sweden)

    Lampert Winfried

    2005-04-01

    Full Text Available Abstract Background In lakes with a deep-water algal maximum, herbivorous zooplankton are faced with a trade-off between high temperature but low food availability in the surface layers and low temperature but sufficient food in deep layers. It has been suggested that zooplankton (Daphnia faced with this trade-off distribute vertically according to an "Ideal Free Distribution (IFD with Costs". An experiment has been designed to test the density (competition dependence of the vertical distribution as this is a basic assumption of IFD theory. Results Experiments were performed in large, indoor mesocosms (Plankton Towers with a temperature gradient of 10°C and a deep-water algal maximum established below the thermocline. As expected, Daphnia aggregated at the interface between the two different habitats when their density was low. The distribution spread asymmetrically towards the algal maximum when the density increased until 80 % of the population dwelled in the cool, food-rich layers at high densities. Small individuals stayed higher in the water column than large ones, which conformed with the model for unequal competitors. Conclusion The Daphnia distribution mimics the predictions of an IFD with costs model. This concept is useful for the analysis of zooplankton distributions under a large suite of environmental conditions shaping habitat suitability. Fish predation causing diel vertical migrations can be incorporated as additional costs. This is important as the vertical location of grazing zooplankton in a lake affects phytoplankton production and species composition, i.e. ecosystem function.

  15. How internal waves influence the vertical distribution of zooplankton

    OpenAIRE

    Rinke, Karsten; Hübner, Ina; Petzoldt, Thomas; Rolinski, Susanne; König-Rinke, Marie; Post, Johannes; Lorke, Andreas; Benndorf, Jürgen

    2007-01-01

    1. We present data with a high spatio-temporal resolution from a 72-h field survey in Bautzen Reservoir (Saxony, Germany). The aims of this survey were to observe hydrophysical processes during a period of unstable stratification in spring and investigate the effect of wind-induced internal waves on the vertical distribution of zooplankton.2. Wind velocities up to 10 m s)1 caused a strong downwelling event of warm water at the sampling site and led to the generation of internal waves with an ...

  16. Initial size structure of natural phytoplankton communities determines the response to Daphnia diel vertical migration

    OpenAIRE

    Maarten Boersma; Florian Haupt; Maria Stockenreiter; Herwig Stibor

    2012-01-01

    Diel vertical migration (DVM) is a common behavior of many pelagic herbivorous zooplankton species in response to predation pressure. It is characterized by a twice daily habitat shift of the zooplankton species: staying in the epilimnion only during night time and migrating down in the crack of dawn in deeper water layers, staying there during the day time. This causes a discontinuous grazing regime and previous studies have shown that the direction and strength of phytoplankton community re...

  17. Trade-offs in the vertical distribution of zooplankton: ideal free distribution with costs?

    OpenAIRE

    Lampert, Winfried; McCauley, Edward; Manly, Bryan F J

    2003-01-01

    Zooplankton vertical migratory patterns are a classic example of optimal habitat choice. We hypothesize that zooplankton distribute themselves vertically in the water column according to an ideal free distribution (IFD) with costs such as to optimize their fitness. In lakes with a deep-water chlorophyll maximum, zooplankton are faced with a trade-off, either experiencing high food (high reproductive potential) but low temperature (slow development) in the hypolimnion or high temperature and l...

  18. Schooling of the vertically migrating mesopelagic fish Maurolicus muelleri in light summer nights

    OpenAIRE

    Kaartvedt, Stein; Knutsen, Tor; Holst, Jens Christian

    1998-01-01

    Vertically migrating Maurolicus muelleri arrested their nocturnal ascent below the peak zooplankton concentrations during Light summer nights at 62 degrees N. At 69 degrees N, the behavior was further modified, with M, muelleri forming schools in the upper layer at night. We suggest that M. muelleri used schooling as an antipredator strategy due to the absence of dark periods.

  19. Turbulence and zooplankton production: insights from PROVESS

    DEFF Research Database (Denmark)

    Visser, Andre; Stips, A.

    2002-01-01

    Zooplankton are directly influenced by turbulence in both a passive and an active manner. Passively, zooplankton are at the mercy of turbulence in how it affects their vertical mixing, encounter rate, detection abilities and feeding current efficiency. Many zooplankton species, however, are actively able to mitigate the effects of turbulence by modifying their behaviour, e.g. vertical migration, prey switching and habituation to hydromechanical stimuli. Both theoretical treatments of these proce...

  20. Vertical oceanic transport of alpha-radioactive nuclides by zooplankton fecal pellets

    International Nuclear Information System (INIS)

    This paper gives the results of research to explain the role played by marine plankton metabolism in the vertical oceanic transport of the alpha-emitting nuclides. The common Mediterranean euphausiid, Meganyctiphanes norvegica, was selected as the typical zooplanktonic species that is the focus of this work. Measurements of 239240Pu, 238U, 232Th, and 210Po are reported in whole euphausiids and in euphausiid fecal pellets and molts. The resulting data are inserted into a simple model that describes the flux of an element through a zooplanktonic animal. Concentrations of the nuclides concerned are high in fecal pellets, at levels which are typical of geological rather than biological material. It is suggested that zooplanktonic fecal pellets play a significant role in the vertical oceanic transport of plutonium, thorium, and polonium

  1. Seasonal variations in vertical migration of glacier lanternfish, Benthosema glaciale

    KAUST Repository

    Dypvik, Eivind

    2012-06-05

    The seasonal variations in glacier lanternfish (Benthosema glaciale) vertical distribution and diel vertical migration (DVM) were studied by use of a bottom-mounted upward-facing 38 kHz echo sounder deployed at 392 m depth and cabled to shore in Masfjorden (~6052?N, ~524?E), Norway. Acoustic data from July 2007-October 2008 were analyzed, and scattering layers below ~220 m during daytime were attributed to glacier lanternfish based on net sampling in this, and previous studies, as well as from analysis of the acoustic data. At these depths, three different diel behavioral strategies were apparent: normal diel vertical migration (NDVM), inverse DVM (IDVM), and no DVM (NoDVM). NoDVM was present all year, while IDVM was present in autumn and winter, and NDVM was present during spring and summer. The seasonal differences in DVM behavior seem to correlate with previously established seasonal distribution of prey. We hypothesize that in regions with seasonally migrating zooplankton, such as where calanoid copepods overwinter at depth, similar plasticity in DVM behavior might occur in other populations of lanternfishes. 2012 The Author(s).

  2. Dissipation Rate of Turbulent Kinetic Energy in Diel Vertical Migrations: Comparison of ANSYS Fluent Model to Measurements

    Science.gov (United States)

    Dean, Cayla; Soloviev, Alexander; Hirons, Amy; Frank, Tamara; Wood, Jon

    2015-04-01

    Recent studies suggest that diel vertical migrations of zooplankton may have an impact on ocean mixing, though details are not completely clear. A strong sound scattering layer of zooplankton undergoing diel vertical migrations was observed in Saanich Inlet, British Colombia, Canada by Kunze et al. (2006). In this study, a shipboard 200-kHz echosounder was used to track vertical motion of the sound scattering layer, and microstructure profiles were collected to observe turbulence. An increase of dissipation rate of turbulent kinetic energy by four to five orders of magnitude was measured during diel vertical migrations of zooplankton in one case (but not observed during other cases). A strong sound scattering layer undergoing diel vertical migration was also observed in the Straits of Florida via a bottom mounted acoustic Doppler current profiler at 244 m isobath. A 3-D non-hydrostatic computational fluid dynamics model with Lagrangian particle injections (a proxy for migrating zooplankton) via a discrete phase model was used to simulate the effect of diel vertical migrations on the turbulence for both Saanich Inlet and the Straits of Florida. The model was initialized with idealized (but based on observation) density and velocity profiles. Particles, with buoyancy adjusted to serve as a proxy for vertically swimming zooplankton, were injected to simulate diel vertical migration cycles. Results of models run with extreme concentrations of particles showed an increase in dissipation rate of turbulent kinetic energy of approximately five orders of magnitude over background turbulence during migration of particles in both Saanich Inlet and the Straits of Florida cases (though direct relation of the turbulence produced by buoyant particles and swimming organisms isn't straightforward). This increase was quantitatively consistent, with turbulence measurements by Kunze et al. (2006). When 10 times fewer particles were injected into the model, the effect on dissipation rate of turbulent kinetic energy was an order of magnitude smaller than that from the extreme concentration. At a concentration of particles 100 times smaller than the extreme concentration, there was no longer an observable effect. In the Straits of Florida, direct turbulence measurements were not available to make a quantitative comparison. However, a small, but statistically significant decrease in northward current velocity profiles during migration times were observed after averaging these profiles over 11 months. A small decrease of current velocity connected to the vertical migrations of particles was reproduced in the Straits of Florida model case. The deviations in the velocity profiles can be explained by the increase in turbulent mixing during vertical migration periods.

  3. Elastic kirchhoff migration for vertical seismic profiles

    International Nuclear Information System (INIS)

    Elastic Kirchhoff migration is implemented for the VSP recording geometry. The resulting migration formula requires measurement of the stress as well as the displacement. Since stress is not measured in a VSP, and in many cases the horizontal component of displacement is not measured, approximate migration formulas are given for these cases. The elastic migration formula for the case where only the vertical components are available, is the same as the acoustic migration formula, where the pressure data are replaced by the magnitudes of the elastic data as reconstructed from the vertical components, and the acoustic Green's functions are replaced with either the P or S wave elastic Green's functions. Two expressions for migration of two component displacement data are presented. In the first, the terms involving traction data are simply ignored. In the second, an improved backpropagation operator for the displacement field is obtained by replacing the traction data in the Kirchhoff integral by displacement data using Hooke's law. The migration expressions for the cases where two component data are available produce images which are less contaminated by artifacts than the migration images of one component data

  4. Diel vertical migration in marine dinoflagellates

    OpenAIRE

    Jephson, Therese

    2012-01-01

    Increasing precipitation and surface water temperature due to global change may strengthen stratification in coastal regions, which could influence the behavior of dinoflagellate diel vertical migration (DVM). DVM is a behavioral mechanism by which dinoflagellates can access photosynthetically active radiation near the surface, and nutrients at depth. During this process, cells may need to cross both salinity and temperature gradients (haloclines and thermoclines, respectively). My results sh...

  5. Vertical migration and diel feeding periodicity of the skinnycheek lanternfish (Benthosema pterotum) in the Red Sea

    KAUST Repository

    Dypvik, Eivind

    2012-11-13

    The vertical migration and diel feeding periodicity of the skinnycheek lanternfish (Benthosema pterotum) were studied by use of a hull-mounted 38 kHz echo sounder, ROV-deployments and net-sampling at two locations (?24°48?N, ?36°15?E and ?21°27?N, ?38°5?E) in the central Red Sea. The mesopelagic zone of the Red Sea represents an unusual environment with very high temperatures (?22 °C) and low zooplankton concentrations (<10 individuals m?3 below 600 m). The skinnycheek lanternfish performed normal diel vertical migration from ?500 to 750 m during daytime to the epipelagic zone (upper ?200 m) at night. A strict feeding periodicity occurred; with the skinnycheek lanternfish foraging on zooplankton throughout the night, while rapidly digesting the preceding nocturnal meal in the warm mesopelagic region. We hypothesize that the constrained epipelagic distribution of zooplankton and the unusual warm waters of the Red Sea force the whole population to ascend and feed in epipelagic waters every night, as the prey-ration eaten each night is fully digested at mesopelagic depths during daytime.

  6. Internal wave-mediated shading causes frequent vertical migrations in fishes

    KAUST Repository

    Kaartvedt, Stein

    2012-04-25

    We provide evidence that internal waves cause frequent vertical migrations (FVM) in fishes. Acoustic data from the Benguela Current revealed that pelagic scattering layers of fish below ~140 m moved in opposite phases to internal waves, ascending ~20 m towards the wave trough and descending from the wave crest. At the trough, the downward displacement of upper waters and the upward migration of fish created an overlapping zone. Near-bottom fish correspondingly left the benthic boundary zone at the wave trough, ascending into an acoustic scattering layer likely consisting of zooplankton and then descending to the benthic boundary zone at the wave crest. We suggest that this vertical fish migration is a response to fluctuations in light intensity of 3 to 4 orders of magnitude caused by shading from a turbid surface layer that had chlorophyll a values of 3 to 4 mg m?3 and varied in thickness from ~15 to 50 m at a temporal scale corresponding to the internal wave period (30 min). This migration frequency thus is much higher than that of the common and widespread light-associated diel vertical migration. Vertical movements affect prey encounters, growth, and survival. We hypothesize that FVM increase the likelihood of prey encounters and the time for safe visual foraging among planktivorous fish, thereby contributing to efficient trophic transfer in major upwelling areas.

  7. Differences in vertical and horizontal distribution of fish larvae and zooplankton, related to hydrography

    DEFF Research Database (Denmark)

    Höffle, Hannes; Nash, Richard D.M.

    2013-01-01

    Planktonic fish larvae have little influence on their horizontal distribution, while they are able to control their vertical position in the water column. While prey and light are among the factors with an apparent influence on the vertical distribution, the effects of other factors are less clear. Notably, distributional differences between larvae of different fish species are poorly understood. Information on the horizontal distribution of larvae of 27 species and the vertical distribution of seven species of Gadidae, two Pleuronectidae and one Scophthalmidae, was compiled from one survey in the northern North Sea. Horizontally, fish larvae aggregated near frontal structures, correlating with high densities of zooplankton. Increasing length and decreasing numbers indicated an origin in the western North Sea, followed by an eastward drift. Vertically, the different species exhibited similarities but also notable differences in their vertical distribution. Most gadoid species aggregated in the upper (B40 m)or middle water column (40 m) during the day with an increase in abundance at shallower depths during the night, while all flatfish were distributed at greater depths under all light conditions. Hence, larvae differed in their distributional patterns, but the relative depth distributions among the species in the larval community generally remained constant

  8. Do Daphnia use metalimnetic organic matter in a north temperate lake? An analysis of vertical migration

    Science.gov (United States)

    Brosseau, Chase Julian; Cline, Timothy J.; Cole, Jonathan J.; Hodgson, James R.; Pace, Michael L.; Weidel, Brian C.

    2012-01-01

    Diel vertical migration of zooplankton is influenced by a variety of factors including predation, food, and temperature. Research has recently shifted from a focus on factors influencing migration to how migration affects nutrient cycling and habitat coupling. Here we evaluate the potential for Daphnia migrations to incorporate metalimnetic productivity in a well-studied northern Wisconsin lake. We use prior studies conducted between 1985 and 1990 and current diel migration data (2008) to compare day and night Daphnia vertical distributions with the depth of the metalimnion (between the thermocline and 1% light depth). Daphnia migrate from a daytime mean residence depth of between about 1.7 and 2.5 m to a nighttime mean residence depth of between 0 and 2.0 m. These migrations are consistent between the prior period and current measurements. Daytime residence depths of Daphnia are rarely deep enough to reach the metalimnion; hence, metalimnetic primary production is unlikely to be an important resource for Daphnia in this system.

  9. Bacteria dispersal by hitchhiking on zooplankton

    DEFF Research Database (Denmark)

    Grossart, Hans-Peter; Dziallas, Claudia

    2010-01-01

    Microorganisms and zooplankton are both important components of aquatic food webs. Although both inhabit the same environment, they are often regarded as separate functional units that are indirectly connected through nutrient cycling and trophic cascade. However, research on pathogenic and nonpathogenic bacteria has shown that direct association with zooplankton has significant influences on the bacteria's physiology and ecology. We used stratified migration columns to study vertical dispersal of hitchhiking bacteria through migrating zooplankton across a density gradient that was otherwise impenetrable for bacteria in both upward and downward directions (conveyor-belt hypothesis). The strength of our experiments is to permit quantitative estimation of transport and release of associated bacteria: vertical migration of Daphnia magna yielded an average dispersal rate of 1.3 x 10(5) x cells x Daphnia(-1) x migration cycle(-1) for the lake bacterium Brevundimonas sp. Bidirectional vertical dispersal by migrating D. magna was also shown for two other bacterial species, albeit at lower rates. The prediction that diurnally migrating zooplankton acquire different attached bacterial communities from hypolimnion and epilimnion between day and night was subsequently confirmed in our field study. In mesotrophic Lake Nehmitz, D. hyalina showed pronounced diel vertical migration along with significant diurnal changes in attached bacterial community composition. These results confirm that hitchhiking on migrating animals can be an important mechanism for rapidly relocating microorganisms, including pathogens, allowing them to access otherwise inaccessible resources.

  10. Vertical distribution of zooplankton in the water column of Lago Amapá, Rio Branco, Acre, Brazil

    Directory of Open Access Journals (Sweden)

    Erlei Cassiano Keppeler

    2004-06-01

    Full Text Available The aim of investigation was to study the model of vertical distribution in Lago Amapá, taking into consideration the seasonality of its zooplanktonic composition. Lago Amapá (10º2'36"S and 67º50'24"W is located in the floodplain of the Rio Acre. Samplings were conducted at three different depths of the water column, to study the vertical distribution of zooplankton populations and determine some physico-chemical and biological parameters of Lago Amapá. Weekly samples were taken with a Van Dorn sampler. The species showed greater concentrations at the by means of water column. Thirty-eight zooplankton species were found in the samples represented by Rotifera (30, Cladocera (5 and Cyclopoida (3. The temperature of the water column showed a tendency toward relatively high values (about 30ºC with little variation, consequently resulting in low viscosity. Based of Jaccard's index, it was seen that during the low-water phase, S1 and S3 of the three sampling stations studied, had greater similarity (Cj = 0.7058 in the middle of the water column. Lago Amapá showed characteristics in line with the intermediate disturbance hypothesis model, favoring colonization by opportunistic species such as rotifers.O objetivo desta investigação foi observar a distribuição vertical da comunidade do zooplâncton no Lago Amapá (10º2'36"S e 67º50'24"W, localizado na planície de inundação do Rio Acre. Amostragens foram conduzidas em três diferentes profundidades da coluna da água, considerando aspectos sazonais do zooplâncton, parâmetros físicos, químicos e biológicos. Coletas foram realizadas semanalmente com Garrafa de Van Dorn. As espécies apresentaram maiores concentrações no meio da coluna da água. Foram encontradas 38 espécies, assim distribuídas: Rotifera (30, Cladocera (5 e Cyclopoida (3. A temperatura da coluna da água em geral apresentou-se alta, em torno de 30ºC, com pequena variação, resultando em baixa viscosidade. O índice de Jaccard, comparando-se as três estações de coletas, demonstrou que durante a fase de águas baixas, as estações 1 e 3 foram as mais similares (Cj = 0.7058, especialmente no meio da coluna da água. Lago Amapá apresentou características em conformidade com o Modelo do Distúrbio Intermediário, favorecendo a colonização de grupos oportunistas, tais como rotíferos.

  11. Vertical distribution of zooplankton in the water column of Lago Amapá, Rio Branco, Acre, Brazil

    Scientific Electronic Library Online (English)

    Erlei Cassiano, Keppeler; Elsa Rodrigues, Hardy.

    2004-06-01

    Full Text Available O objetivo desta investigação foi observar a distribuição vertical da comunidade do zooplâncton no Lago Amapá (10º2'36"S e 67º50'24"W), localizado na planície de inundação do Rio Acre. Amostragens foram conduzidas em três diferentes profundidades da coluna da água, considerando aspectos sazonais do [...] zooplâncton, parâmetros físicos, químicos e biológicos. Coletas foram realizadas semanalmente com Garrafa de Van Dorn. As espécies apresentaram maiores concentrações no meio da coluna da água. Foram encontradas 38 espécies, assim distribuídas: Rotifera (30), Cladocera (5) e Cyclopoida (3). A temperatura da coluna da água em geral apresentou-se alta, em torno de 30ºC, com pequena variação, resultando em baixa viscosidade. O índice de Jaccard, comparando-se as três estações de coletas, demonstrou que durante a fase de águas baixas, as estações 1 e 3 foram as mais similares (Cj = 0.7058), especialmente no meio da coluna da água. Lago Amapá apresentou características em conformidade com o Modelo do Distúrbio Intermediário, favorecendo a colonização de grupos oportunistas, tais como rotíferos. Abstract in english The aim of investigation was to study the model of vertical distribution in Lago Amapá, taking into consideration the seasonality of its zooplanktonic composition. Lago Amapá (10º2'36"S and 67º50'24"W) is located in the floodplain of the Rio Acre. Samplings were conducted at three different depths o [...] f the water column, to study the vertical distribution of zooplankton populations and determine some physico-chemical and biological parameters of Lago Amapá. Weekly samples were taken with a Van Dorn sampler. The species showed greater concentrations at the by means of water column. Thirty-eight zooplankton species were found in the samples represented by Rotifera (30), Cladocera (5) and Cyclopoida (3). The temperature of the water column showed a tendency toward relatively high values (about 30ºC) with little variation, consequently resulting in low viscosity. Based of Jaccard's index, it was seen that during the low-water phase, S1 and S3 of the three sampling stations studied, had greater similarity (Cj = 0.7058) in the middle of the water column. Lago Amapá showed characteristics in line with the intermediate disturbance hypothesis model, favoring colonization by opportunistic species such as rotifers.

  12. Vertical and horizontal distribution of zooplankton and polar cod in southern Baffin Bay (66-71°N) in September 2009

    DEFF Research Database (Denmark)

    Kjellerup, Sanne; Dünweber, Michael

    2015-01-01

    Zooplankton are the link connecting primary producers to higher trophic levels, and knowing their distribution and community is important for predicting the distribution of predator species, like fish, seabirds, and marine mammals. However, data from open Arctic oceans are still scarce. In autumn, tens of millions of the planktivorous little auks (Alle alle) (about 75 % of the world’s population) and millions of thick-billed murres (Uria lomvia) pass through the Baffin Bay. To investigate their potential food sources, we investigated the spatial and vertical distribution of zooplankton and small fishes in the upper 500 m of southern Baffin Bay in September 2009. The zooplankton community was dominated by copepods (55 % of abundance in the upper 500 m), primarily of the genus Calanus. Other important zooplankton taxa included Limacina helicina, Chaetognatha, and Cirripedia nauplii. On the Greenland Shelf, most Calanus were late copepodite stages and most were found at the depths of >200 m, suggesting they werein diapause. On the Canadian Shelf, there were relatively more Calanus in the near-surface layers, which were probably still actively feeding and which were available to visual predators such as seabirds and fish. The acoustic survey showed the highest density of polar cod Boreogadus saida in the upper 50 m on the western part of the Greenland Shelf. A particularly high biomass of both zooplankton and polar cod was found in the central part of the basin in association with a local relatively shallow area

  13. Diel Vertical Migration Thresholds of Karenia brevis (Dinophyceae).

    Science.gov (United States)

    Light and nutrient availability change throughout dinoflagellate diel vertical migration (DVM) and/or with subpopulation location in the water column along the west Florida shelf. Typically, the vertical depth of the shelf is greater than the distance a subpopulation can vertical...

  14. Vertical distribution, composition, and abundance of crustacean zooplankton in the offshore waters of Lake Michigan

    International Nuclear Information System (INIS)

    During 1975, zooplankton samples were collected on eight cruises (April to November) in the southern basin of Lake Michigan. Four stations in the northern basin were also sampled in January during a cruise aboard the USCGC Westwind. One of the goals of this study was to quantitatively estimate the standing crop of herbivorous crustacean zooplankton in units that would represent their functional roles as consumers of phytoplankton

  15. Diel vertical migration in deep sea plankton is finely tuned to latitudinal and seasonal day length.

    Science.gov (United States)

    van Haren, Hans; Compton, Tanya J

    2013-01-01

    Diel vertical migration (DVM) is a ubiquitous phenomenon in marine and freshwater plankton communities. Most commonly, plankton migrate to surface waters at dusk and return to deeper waters at dawn. Up until recently, it was thought that DVM was triggered by a relative change in visible light intensity. However, evidence has shown that DVM also occurs in the deep sea where no direct and background sunlight penetrates. To identify whether such DVM is associated with latitudinal and seasonal day light variation, one and a half years of recorded acoustic data, a measure of zooplankton abundance and movement, were examined. Acoustic Doppler current profilers, moored at eight different sub-tropical latitudes in the North-Atlantic Ocean, measured in the vertical range of 500-1600 m. DVM was observed to follow day length variation with a change in season and latitude at all depths. DVM followed the rhythm of local sunrise and sunset precisely between 500 and 650 m. It continued below 650 m, where the deepest penetrable irradiance level are solar diurnal and seasonal rhythms in deep sea plankton motions. In accordance with this hypothesis, the deepest plankton were consistently the first to migrate upwards. PMID:23717613

  16. Effects of net cages on the vertical distribution of zooplankton in a semi-arid reservoir, northeastern Brazil / Interferência de tanques-rede na distribuição vertical do zooplâncton num açude do semi-árido, nordeste do Brasil

    Scientific Electronic Library Online (English)

    Glécia Trinta de Paula, Freitas; Maria Cristina, Crispim; Hênio do Nascimento de, Melo Júnior.

    2012-06-01

    Full Text Available OBJETIVO: O açude do Carneiro é um ambiente aquático utilizado para atividades de aquicultura em tanques-rede, localizado na região semi-árida do nordeste do Brasil. A distribuição vertical foi avaliada com a finalidade de determinar os efeitos do enriquecimento orgânico induzido pela aquicultura no [...] s movimentos do zooplâncton. MÉTODOS: três réplicas amostrais foram coletadas à meia noite (0:00 horas) e ao meio dia (12:00 horas ) em cada uma de três profundidades da coluna d'água (i.e. superfície: 0 m; meio: 2 m e fundo: 4 m) em duas áreas (próximo e distante dos tanques-rede). As amostras foram coletadas utilizando uma garrafa de Van Dorn com 3 L de capacidade volumétrica. Os indivíduos coletados foram preservados em uma solução de formol a 4% saturada com açúcar e, posteriormente, identificados e quantificados com uma câmara de contagem Sedgwick-Rafter sob microscópio, considerando um mínimo de 100 indivíduos por subamostra. RESULTADOS: a riqueza de espécies e a densidade foram maiores na estação N (próxima aos tanques-rede) quando comparadas com a estação F (distante dos tanques-rede). Com poucas exceções, espécies de Rotifera não exibiram padrões típicos de migração vertical, concentrando-se nas camadas mais profundas durante o dia e nas camadas intermediárias durante a noite. Brachionus dolabratus e Hexarthra mira foram as únicas espécies que mostraram padrões de migração vertical inversos na estação N, em oposição aos padrões do copépodo ciclopóide Termocyclops crassus. Além disso, padrões de migração vertical não foram claros para as espécies de Cladocera e Copepoda próximos aos tanques-rede, mas foram evidentes na estação F. CONCLUSÕES: a presença de tanques-rede para peixes aumentou a riqueza de espécies (a maioria rotíferos) e a densidade de zooplâncton. Movimentos verticais foram mais pronunciados nos locais distantes dos tanques-rede, sugerindo que o aumento da disponibilidade de alimento reduziu a necessidade dos movimentos verticais típicos durante o dia, nos locais próximos aos tanques-rede. Abstract in english AIM: Carneiro reservoir is an aquatic environment used for net cage aquaculture activities, located in the semi-arid region of northeastern Brazil. Vertical distribution was evaluated in order to determine the effects of organic enrichment induced by aquaculture on zooplankton movements. METHODS: th [...] ree replicate samples were collected during midday and midnight at each of three depths along the water column (i.e. surface: 0 m; middle: 2 m and bottom: 4 m) at two sites (near and far from the net cages). Samples were collected using a 3 L volume capacity Van Dorn bottle. The collected individuals were preserved in a 4% formaldehyde solution saturated with sugar and, later, identified and counted on a Sedgwick-Rafter chamber under a microscope, considering a minimum of 100 individuals per subsample. RESULTS: higher species richness and density were observed at the N station (nearby the net cages) compared to the F station (distant from the net cages). With few exceptions, Rotifer species did not exhibit typical vertical migration patterns, concentrating at bottom depths during daytime and at intermediate depths during nighttime. Brachionus dolabratus and Hexarthra mira were the only species to show reverse vertical migration at the N station, in opposition to patterns of the cyclopoid copepod Termocyclops crassus. Furthermore, vertical migration patterns were not clear for Cladocera and Copepoda species nearby the net cages, but were rather clear at the F station. CONCLUSIONS: the presence of fish net cages increased zooplankton species richness (mostly rotifers) and density. Vertical movements were more pronounced at sites distant from net cages, suggesting that the increased food availability reduced the need for the typical vertical movements during daytime at sites nearby the net cages.

  17. Effects of net cages on the vertical distribution of zooplankton in a semi-arid reservoir, northeastern Brazil Interferência de tanques-rede na distribuição vertical do zooplâncton num açude do semi-árido, nordeste do Brasil

    Directory of Open Access Journals (Sweden)

    Glécia Trinta de Paula Freitas

    2012-06-01

    Full Text Available AIM: Carneiro reservoir is an aquatic environment used for net cage aquaculture activities, located in the semi-arid region of northeastern Brazil. Vertical distribution was evaluated in order to determine the effects of organic enrichment induced by aquaculture on zooplankton movements. METHODS: three replicate samples were collected during midday and midnight at each of three depths along the water column (i.e. surface: 0 m; middle: 2 m and bottom: 4 m at two sites (near and far from the net cages. Samples were collected using a 3 L volume capacity Van Dorn bottle. The collected individuals were preserved in a 4% formaldehyde solution saturated with sugar and, later, identified and counted on a Sedgwick-Rafter chamber under a microscope, considering a minimum of 100 individuals per subsample. RESULTS: higher species richness and density were observed at the N station (nearby the net cages compared to the F station (distant from the net cages. With few exceptions, Rotifer species did not exhibit typical vertical migration patterns, concentrating at bottom depths during daytime and at intermediate depths during nighttime. Brachionus dolabratus and Hexarthra mira were the only species to show reverse vertical migration at the N station, in opposition to patterns of the cyclopoid copepod Termocyclops crassus. Furthermore, vertical migration patterns were not clear for Cladocera and Copepoda species nearby the net cages, but were rather clear at the F station. CONCLUSIONS: the presence of fish net cages increased zooplankton species richness (mostly rotifers and density. Vertical movements were more pronounced at sites distant from net cages, suggesting that the increased food availability reduced the need for the typical vertical movements during daytime at sites nearby the net cages.OBJETIVO: O açude do Carneiro é um ambiente aquático utilizado para atividades de aquicultura em tanques-rede, localizado na região semi-árida do nordeste do Brasil. A distribuição vertical foi avaliada com a finalidade de determinar os efeitos do enriquecimento orgânico induzido pela aquicultura nos movimentos do zooplâncton. MÉTODOS: três réplicas amostrais foram coletadas à meia noite (0:00 horas e ao meio dia (12:00 horas em cada uma de três profundidades da coluna d'água (i.e. superfície: 0 m; meio: 2 m e fundo: 4 m em duas áreas (próximo e distante dos tanques-rede. As amostras foram coletadas utilizando uma garrafa de Van Dorn com 3 L de capacidade volumétrica. Os indivíduos coletados foram preservados em uma solução de formol a 4% saturada com açúcar e, posteriormente, identificados e quantificados com uma câmara de contagem Sedgwick-Rafter sob microscópio, considerando um mínimo de 100 indivíduos por subamostra. RESULTADOS: a riqueza de espécies e a densidade foram maiores na estação N (próxima aos tanques-rede quando comparadas com a estação F (distante dos tanques-rede. Com poucas exceções, espécies de Rotifera não exibiram padrões típicos de migração vertical, concentrando-se nas camadas mais profundas durante o dia e nas camadas intermediárias durante a noite. Brachionus dolabratus e Hexarthra mira foram as únicas espécies que mostraram padrões de migração vertical inversos na estação N, em oposição aos padrões do copépodo ciclopóide Termocyclops crassus. Além disso, padrões de migração vertical não foram claros para as espécies de Cladocera e Copepoda próximos aos tanques-rede, mas foram evidentes na estação F. CONCLUSÕES: a presença de tanques-rede para peixes aumentou a riqueza de espécies (a maioria rotíferos e a densidade de zooplâncton. Movimentos verticais foram mais pronunciados nos locais distantes dos tanques-rede, sugerindo que o aumento da disponibilidade de alimento reduziu a necessidade dos movimentos verticais típicos durante o dia, nos locais próximos aos tanques-rede.

  18. Effects of diel vertical migration on ephippia production in Daphnia

    OpenAIRE

    Alekseev, Victor

    2004-01-01

    Fish presence in experimentally simulated temperature conditions (limno-towers) led to diel vertical migration and resulted in a decrease of ephippia production in Daphnia pulicaria. Diel fluctuation of food, temperature and day length similar to those experienced by migrating Daphnia were tested in laboratory experiments with flow-through-systems. Daphnids were kept under these conditions for 15 days and the proportions of females producing an ephippium were determined. In addition, maturati...

  19. Turbulence and zooplankton production: insights from PROVESS

    DEFF Research Database (Denmark)

    Visser, Andre; Stips, A.

    2002-01-01

    Zooplankton are directly influenced by turbulence in both a passive and an active manner. Passively, zooplankton are at the mercy of turbulence in how it affects their vertical mixing, encounter rate, detection abilities and feeding current efficiency. Many zooplankton species, however, are actively able to mitigate the effects of turbulence by modifying their behaviour, e.g. vertical migration, prey switching and habituation to hydromechanical stimuli. Both theoretical treatments of these processes and field observations from the northern North Sea are examined. Field observations show that some copepod species actively migrate to avoid high turbulence levels in surface waters. Furthermore, observations show a negative relationship between turbulence and zooplankton ingestion rates. This supports the paradigm of a dome-shaped response for zooplankton production with environmental turbulence. A theoretical treatment shows that the reaction distance, R, for an ambush-feeding copepod feeding on swimming organisms follows R alpha epsilon(-1/6) where epsilon is the turbulent dissipation rate, a result that shows close agreement with previously reported experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.

  20. The distribution and vertical flux of fecal pellets from large zooplankton in Monterey bay and coastal California

    Science.gov (United States)

    Dagg, Michael J.; Jackson, George A.; Checkley, David M.

    2014-12-01

    We sampled zooplankton and fecal pellets in the upper 200 m of Monterey Bay and nearby coastal regions in California, USA. On several occasions, we observed high concentrations of large pellets that appeared to be produced during night-time by dielly migrating euphausiids. High concentrations of pellets were found in near-surface waters only when euphausiids co-occurred with high concentrations of large (>10 ?m) phytoplankton. Peak concentrations of pellets at mid-depth (100 or 150 m) during the day were consistent with the calculated sinking speeds of pellets produced near the surface at night. At these high flux locations (HI group), pellet concentrations declined below mid-depth. In contrast, at locations where the phytoplankton assemblage was dominated by small phytoplankton cells (populations were high. Protozooplankton concentrations did not affect this pattern. We concluded that the day and night differences in pellet concentration and flux in the HI profiles were mostly due to sinking of dielly-pulsed inputs in the surface layer, and that small zooplankton (Oithona, Oncaea), heterotrophic dinoflagellates, and bacterial activity probably caused some pellet degradation or consumption below 100 m. We estimated that consumption of sinking pellets by large copepods was insignificant. High fluxes of pellets were episodic because they required both high concentrations of large phytoplankton and large stocks of euphausiids. Under these conditions, flux events overwhelmed retention mechanisms, resulting in large exports of organic matter from the upper 200 m.

  1. Reproducing 137Cs vertical migration in Spanish soils - Reproducing 137Cs and 90Sr vertical migration in Spanish mainland

    International Nuclear Information System (INIS)

    As a result of caesium's and strontium's activity migration study developed in Spanish mainland soils, there has been obtained convective - diffusive migration equation that will reproduce adequately the movement that an activity deposit would follow in this land. Taking into account the dependence on rain that apparent convection velocity shows, it has been defined a new migration parameter that depends only on soil's properties. By means of a least square method and fitting the migration equation to experimental activity profiles, the values showed by the migration parameters in the studied soils, characteristics of that area, have been obtained. After that, there have been obtained the mean values of these parameters for each defined group that, depending on soil's texture, have been observed in the study performed about the movement of both radionuclides in soils and to whom these soils belong. Using these mean values and obtained equation, it has been properly reproduce those vertical activity profiles that were experimentally determined. In order to validate these values, a new sampling programme is carrying out in the north of Spain and, with obtained new sampling points' information, is going to verify if, indeed, obtained mean values also reproduce these new sampling points' activity vertical profile. (authors)

  2. Diel vertical migration arising in a habitat selection game

    DEFF Research Database (Denmark)

    Sainmont, Julie; Thygesen, Uffe Høgsbro; Visser, Andre

    2013-01-01

    Predator and prey react to each other, adjusting their behavior to maximize their fitness and optimizing their food intake while keeping their predation risk as low as possible. In a pelagic environment, prey reduce their predation mortality by adopting a diel vertical migration (DVM) strategy, avoiding their predator during their peak performance by finding refuge in deep layers during daylight hours and feeding at the surface during the night. Due to the duality of the interaction between prey...

  3. Optimal foraging and diel vertical migration in a life history model

    DEFF Research Database (Denmark)

    Sainmont, Julie; Andersen, Ken Haste

    Zooplankton such as copepods are known to perform diel vertical migration, avoiding the food rich surface during bright hours to avoid visual predator when they are most dangerous, and returning to the surface to feed at night. The resolution of this foraging behaviour requires fine time scale in the model, unsuited for life history modeling. We propose a method based on optimal foraging theory to take into account the emergent feeding rates as a function of the copepod metabolic cost, latitude, time and predation. We predict that copepods will balance their growth rate and mortality, playing a safe strategy when food is plentiful, but taking greater risks at low food concentrations. We apply these concepts to high latitude ecosystems where there is a strong seasonal variation in both food availability and day length. Specifically, during the summer, the midnight sun will force the animals to take more risk and maintain some feeding at the surface to cover their nutritional needs, compensate for predationmortality and sustain their growth

  4. Inverse vertical migration and feeding in glacier lanternfish (Benthosema glaciale)

    KAUST Repository

    Dypvik, Eivind

    2011-11-08

    A bottom-mounted upward-facing 38-kHz echo sounder was deployed at ~400 m and cabled to shore in Masfjorden (~60 52?N, ~5 24?E), Norway. The scattering layers seen during autumn (September-October) 2008 were identified by trawling. Glacier lanternfish (Benthosema glaciale) were mainly distributed below ~200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study. It consisted of 2-year and older individuals migrating to ~200-270 m during the daytime, while descending back to deeper than ~270 m during the night. Stomach content analysis revealed increased feeding during the daytime on overwintering Calanus sp. We conclude that visually searching glacier lanternfish performing IDVM benefit from the faint daytime light in mid-waters when preying on overwintering Calanus sp. 2011 The Author(s).

  5. Inverse vertical migration and feeding in glacier lanternfish (Benthosema glaciale)

    OpenAIRE

    Dypvik, Eivind; Klevjer, Thor A.; Kaartvedt, Stein

    2011-01-01

    A bottom-mounted upward-facing 38-kHz echo sounder was deployed at ~400 m and cabled to shore in Masfjorden (~60°52?N, ~5°24?E), Norway. The scattering layers seen during autumn (September–October) 2008 were identified by trawling. Glacier lanternfish (Benthosema glaciale) were mainly distributed below ~200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study. It con...

  6. Diatom vertical migration within land-fast Arctic sea ice

    Science.gov (United States)

    Aumack, C. F.; Juhl, A. R.; Krembs, C.

    2014-11-01

    Light levels inside first-year, landfast sea ice were experimentally altered by manipulating overlying snow depths. Irradiance available for ice algae growing near the ice-bottom, and under the ice, was highly dependent on snow depths ranging from 0 to > 30 cm. Importantly, algal vertical distributions also changed under different irradiances. Under thick snow (low light), the majority of algae were found several cm above the ice-seawater interface, while progressively more were found nearer the interface at locations with thinner overlying snow (higher light). Short-term field experiments suggested that ice algae were able to reposition themselves within the ice column within 3 days after manipulating snow depths. Laboratory gliding rate measurements of a cultured ice diatom suggested that it is capable of daily cm-scale movement. Vertical migration may help ice diatoms balance opposing light and nutrient resource gradients, similar to strategies used by some benthic and pelagic algae. Moreover, when ice algae congregate near the ice-seawater interface, they may be especially susceptible to loss from the ice environment. Vertical repositioning in response to changing light dynamics may be a mechanism to optimize between vertically-opposing environmental factors and help explain the connection between melting snow cover and export of biomass from sea ice.

  7. Effects of diel vertical migration on ephippia production in Daphnia

    Directory of Open Access Journals (Sweden)

    Victor ALEKSEEV

    2004-09-01

    Full Text Available Fish presence in experimentally simulated temperature conditions (limno-towers led to diel vertical migration and resulted in a decrease of ephippia production in Daphnia pulicaria. Diel fluctuation of food, temperature and day length similar to those experienced by migrating Daphnia were tested in laboratory experiments with flow-through-systems. Daphnids were kept under these conditions for 15 days and the proportions of females producing an ephippium were determined. In addition, maturation time, survival to maturation, size of the first clutch and female dry weight (without eggs on day 15 were traced. The most important factor affecting ephippia production in migrating Daphnia was photoperiod change, and when mother and embryo are exposed to alternating light conditions, these are thought to have the effect on the mother of acting as a signal to stop ephippia production. Such effects might be explained by the different sensitiveness to light intensity in females carrying an embryo and an embryo itself in broods. Fish presence forced Daphnia to stay in low-light conditions during daytime hours, to avoid attacks by fish. The Daphnia were able to check light intensity constantly by short vertical jumps above a light-threshold that was confirmed experimentally in limno-towers. The dim conditions were possibly light enough for adults to check day length, but were too dark for embryos shaded by the mother's body. Food conditions played a relatively small role in the process, and no effects of temperature on ephippia production were found. As expected, food affected the size of the first clutch, and temperature controlled the time to maturation. Photoperiod had a marginally significant influence on the time to maturation in Daphnia. A hypothesis on the role of photoperiod as the key factor for Daphnia life cyclic recurrence and other seasonal adaptations is proposed.

  8. Diel vertical migration arising in a habitat selection game

    DEFF Research Database (Denmark)

    Sainmont, Julie; Thygesen, Uffe HØgsbro

    2013-01-01

    Predator and prey react to each other, adjusting their behavior to maximize their fitness and optimizing their food intake while keeping their predation risk as low as possible. In a pelagic environment, prey reduce their predation mortality by adopting a diel vertical migration (DVM) strategy, avoiding their predator during their peak performance by finding refuge in deep layers during daylight hours and feeding at the surface during the night. Due to the duality of the interaction between prey and predator, we used a game theory approach to investigate whether DVM can be a suitable strategy for the predator as well as the prey. We formulated three scenarios in plankton ecology in order to address this question. A novel finding is that mixed strategies emerge as optimal over a range of the parameter space, where part of the predator or prey population adopts a DVM while the rest adopt one or other "sit and wait" strategies

  9. Effects of net cages on the vertical distribution of zooplankton in a semi-arid reservoir, northeastern Brazil Interferência de tanques-rede na distribuição vertical do zooplâncton num açude do semi-árido, nordeste do Brasil

    OpenAIRE

    Glécia Trinta de Paula Freitas; Maria Cristina Crispim; Hênio do Nascimento de Melo Júnior

    2012-01-01

    AIM: Carneiro reservoir is an aquatic environment used for net cage aquaculture activities, located in the semi-arid region of northeastern Brazil. Vertical distribution was evaluated in order to determine the effects of organic enrichment induced by aquaculture on zooplankton movements. METHODS: three replicate samples were collected during midday and midnight at each of three depths along the water column (i.e. surface: 0 m; middle: 2 m and bottom: 4 m) at two sites (near and far from the n...

  10. Importance des phénomènes de migration verticale des hydrocarbures Significance of Vertical Migration Phenomea of Hydrocarbons

    Directory of Open Access Journals (Sweden)

    Chiarelle A.

    2006-11-01

    Full Text Available Cette publication a pour but de démonter les mécanismes de migration verticale des hydrocarbures et d'en analyser les conséquences, à partir d'exemples concrets choisis sur les domaines d'activité de la Société Nationale Elf Aquitaine (Production [SNEA (PJ. Les hydrocarbures, huile et gaz, rassemblés en phase individualisée évoluent dans un milieu poreux, fin, généralement mouillé à l'eau. Dans un tel environnement la migration suppose des pressions capillaires élevées. On démontre que cette condition se realise plus particulièrement sur Ies zones hautes fermées où les élements d'hydrocarbures expulses de la roche mère peuvent se rassembler en amas de taille importante, développant une forte poussee d'Archimède. De même le gaz, du fait de sa masse volumique faible par rapport à celle de l'eau, manifestera une grande aptitude à la migration verticale, ce qui conduira souvent à une redistribution verticale des hydrocarbures non conforme au schéma diagénétique classique : présence d'un gisement de gaz en surface et huile en profondeur. Combinés à l'effet Gussow, phénomène de refoulement de l'huile par le gaz hors de la fermeture critique d'une structure, les processus envisagés ici, où tes accidents tectoniques tiennent une place importante, aboutiront généralement à sil: aerer spatialement l'huile et le gaz. Ces transferts semblent s'accompagner fréquemment de modifications dans la composition chimique des huiles : augmentation des teneurs en soufre, en métaux traces, en hydrocarbures aromatiques, et alourdissement des huiles The purpose of this article is ta described the vertical migration mechanisms of hydrocarbons and to analyze their conséquences, on the basis of concrete examples selected in the fields of activities carried on by Société Nationale Elf Aquitaine (SNEA. When hydrocarbons (ai( and gas are gathered in a distinct phase, they evolve in a fine porous medium that is usually water wet. In such on environment, migration requires high capillary pressures. lt is shown that such conditions occur especially in high closed zones where the hydrocarbons driven out of the source rock con gather together in a large-sized mass, thus building up a high degree of buoyancy. In the same way, because gas has a louver specific gravity thon water, it has a great tendency ta migrote vertically, which often brings about a vertical redistribution of hydrocarbons that does not conform ta the conventional diagenetic pattern, i. e. the presence of a gas pool above a deeper ail pool.

  11. Depth-selection patterns and diel vertical migration of Daphnia ambigua (Crustacea: Cladocera) in lake El Plateado / Patrones de selección de profundidad y migración vertical de Daphnia ambigua (Crustacea: Cladocera) en el lago El Plateado

    Scientific Electronic Library Online (English)

    RODRIGO, RAMOS-JILIBERTO; LUIS R., ZÚÑIGA.

    2001-09-01

    Full Text Available Los lagos templados y sub-tropicales a menudo presentan una marcada estructura vertical durante la estación cálida que involucra importantes diferencias espaciales de variables físicas, químicas y biológicas. El zooplancton se encuentra por ello expuesto a un ambiente marcadamente heterogéneo en su [...] dimensión vertical. En este trabajo analizamos la distribución vertical del cladócero D. ambigua en el lago eutrófico y monomíctico El Plateado, a mediodía y a medianoche, y su relación con la distribución vertical de la temperatura del agua y concentración de oxígeno disuelto. Intentamos también definir si esta población exhibe o no una conducta de migración vertical. Los resultados muestran cambios significativos en la distribución vertical día/noche de D. ambigua durante su periodo de crecimiento, con excepción de la última fecha. Los datos revelan también que la profundidad promedio seleccionada por D. ambigua disminuye en el tiempo, así como la amplitud de la migración vertical. Dentro del periodo de estratificación del lago, la temperatura aparece positivamente correlacionada y el oxígeno negativamente correlacionado con la frecuencia de D. ambigua. Se sugiere que la concentración de oxígeno juega un papel crucial en la modulación de la conducta de migración vertical de D. ambigua en el lago El Plateado, con importantes consecuencias para el entendimiento del patrón atípico de dinámica poblacional que presenta esta especie Abstract in english Eutrophic temperate and sub-tropical lakes often exhibit a marked vertical structure during the warm season that involves important spatial differences of physical, chemical and biological variables. Therefore, zooplankton is exposed to a highly heterogeneous environment in the vertical dimension. I [...] n this work, We analyze the depth-distribution of the cladoceran Daphnia ambigua in the eutrophic, monomictic lake El Plateado at midday and midnight, along with its relationship with the vertical distribution of water temperature and dissolved oxygen concentration. We also attempt to define whether or not this population exhibits a diel vertical migration. The results show significant changes in the day/night vertical distribution of D. ambigua during its growing season, with the exception of the last date. Also, the data revealed that average depth selected by D. ambigua becomes shallower with time, and the amplitude of the vertical migration decreases throughout the season. During the period of lake stratification, temperature appears positively correlated, and oxygen negatively correlated to the frequency of D. ambigua. It is suggested that oxygen concentration plays a crucial role in modulating the vertical migration behavior of D. ambigua in lake El Plateado, which has important consequences for understanding the atypical pattern of population dynamics exhibited by this species

  12. Potential acidification impacts on zooplankton in CCS leakage scenarios

    International Nuclear Information System (INIS)

    Highlights: • Effects of CCS techniques and ocean acidification on zooplankton are under-studied. • Vulnerable zooplankton are meso-, bathypelagic and vertically migrating species. • Impacts include impaired calcification, reproduction, development and survival. • Need for modelling studies combining physico-chemical with ecological impacts. -- Abstract: Carbon capture and storage (CCS) technologies involve localized acidification of significant volumes of seawater, inhabited mainly by planktonic species. Knowledge on potential impacts of these techniques on the survival and physiology of zooplankton, and subsequent consequences for ecosystem health in targeted areas, is scarce. The recent literature has a focus on anthropogenic greenhouse gas emissions into the atmosphere, leading to enhanced absorption of CO2 by the oceans and a lowered seawater pH, termed ocean acidification. These studies explore the effects of changes in seawater chemistry, as predicted by climate models for the end of this century, on marine biota. Early studies have used unrealistically severe CO2/pH values in this context, but are relevant for CCS leakage scenarios. Little studied meso- and bathypelagic species of the deep sea may be especially vulnerable, as well as vertically migrating zooplankton, which require significant residence times at great depths as part of their life cycle

  13. Vertical and horizontal distribution of zooplankton and polar cod in southern Baffin Bay (66-71°N) in September 2009

    DEFF Research Database (Denmark)

    Kjellerup, Sanne; Dünweber, Michael; Møller, Eva Friis; Schiedek, Doris; Oskarsson, Gudmundur J.; Riget, Frank Farsø; Johansen, Kasper Lambert; Mosbech, Anders

    2015-01-01

    Zooplankton are the link connecting primary producers to higher trophic levels, and knowing their distribution and community is important for predicting the distribution of predator species, like fish, seabirds, and marine mammals. However, data from open Arctic oceans are still scarce. In autumn, tens of millions of the planktivorous little auks (Alle alle) (about 75 % of the world’s population) and millions of thick-billed murres (Uria lomvia) pass through the Baffin Bay. To investigate their ...

  14. Horizontal distribution of Fukushima-derived radiocesium in zooplankton in the northwestern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    M. Kitamura

    2013-08-01

    Full Text Available The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1. Fission products were emitted, falling over a broad range in the Northern Hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radiocesium in zooplankton and in seawater in the western North Pacific Ocean (500–2100 km from the FNPP1 10 months after the accident. 134Cs and 137Cs were detected in zooplankton and seawater from all the stations. Because of its short half-life, the 134Cs detected in our samples could only be derived from the FNPP1 accident. The highest 137Cs activity in zooplankton was the same order of magnitude as it was one month after the accident, and average activity was one or two orders of magnitude higher than 137Cs activities observed before the accident around Japan. Horizontally, the radiocesium activity concentrations in zooplankton were high at around 25° N while those in surface seawater were high at around the transition area between the Kuroshio and the Oyashio currents (36–40° N. We observed subsurface radiocesium maxima in density range of the North Pacific Subtropical Mode Water and the occurrence of many diel vertical migratory zooplankton. These suggested that the high activity concentrations in the subtropical zooplankton at around 25° N were connected to the subsurface radiocesium and active vertical migration of zooplankton. However, the high activity concentrations of radiocesium in subsurface seawater did not necessarily correlate with the higher radiocesium activity in zooplankton. Activity concentrations of radiocesium in zooplankton might be influenced not only by the environmental radiocesium activity concentrations but also by other factors, which are still unknown.

  15. Horizontal distribution of Fukushima-derived radiocesium in zooplankton in the northwestern Pacific Ocean

    Science.gov (United States)

    Kitamura, M.; Kumamoto, Y.; Kawakami, H.; Cruz, E. C.; Fujikura, K.

    2013-08-01

    The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1). Fission products were emitted, falling over a broad range in the Northern Hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radiocesium in zooplankton and in seawater in the western North Pacific Ocean (500-2100 km from the FNPP1) 10 months after the accident. 134Cs and 137Cs were detected in zooplankton and seawater from all the stations. Because of its short half-life, the 134Cs detected in our samples could only be derived from the FNPP1 accident. The highest 137Cs activity in zooplankton was the same order of magnitude as it was one month after the accident, and average activity was one or two orders of magnitude higher than 137Cs activities observed before the accident around Japan. Horizontally, the radiocesium activity concentrations in zooplankton were high at around 25° N while those in surface seawater were high at around the transition area between the Kuroshio and the Oyashio currents (36-40° N). We observed subsurface radiocesium maxima in density range of the North Pacific Subtropical Mode Water and the occurrence of many diel vertical migratory zooplankton. These suggested that the high activity concentrations in the subtropical zooplankton at around 25° N were connected to the subsurface radiocesium and active vertical migration of zooplankton. However, the high activity concentrations of radiocesium in subsurface seawater did not necessarily correlate with the higher radiocesium activity in zooplankton. Activity concentrations of radiocesium in zooplankton might be influenced not only by the environmental radiocesium activity concentrations but also by other factors, which are still unknown.

  16. Horizontal distribution of Fukushima-derived radiocesium in zooplankton in the northwestern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    M. Kitamura

    2013-04-01

    Full Text Available The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1. Fission products were emitted, falling over a broad range in the northern hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radiocesium in zooplankton and in seawater in the western North Pacific Ocean (500–2100 km from the FNPP1 10 months after the accident. 134Cs and 137Cs were detected in zooplankton and seawater from all the stations. Because of its short half-lives, 134Cs detected in our samples could only be derived from the FNPP1 accident. The highest 137Cs activity in zooplankton was same order of magnitude as that one month after the accident, and average activity was one or two orders of magnitude higher than 137Cs activities observed before the accident around Japan. Horizontally, the radiocesium activity concentrations in zooplankton were high at around 25° N while those in surface seawater were high at around the transition area between the Kuroshio and the Oyashio Currents (36–40° N. We observed subsurface radiocesium maxima in density range of the North Pacific Subtropical Mode Water and occurrence of many diel vertical migratory zooplanktons. These suggested that the high activity concentrations in the subtropical zooplankton at around 25° N were connected to the subsurface radiocesium and active vertical migration of zooplankton. However, the high activity concentrations of radiocesium in subsurface seawater did not necessarily follow the higher radiocesium activity in zooplankton. Biological characteristics of zooplankton community possibly influenced how large was contamination of radiocesium in the community but it is still unknown what kind of biological factors were important.

  17. Reproducing {sup 137}Cs vertical migration in Spanish soils - Reproducing {sup 137}Cs and {sup 90}Sr vertical migration in Spanish mainland

    Energy Technology Data Exchange (ETDEWEB)

    Olondo, C.; Legarda, F.; Herranz, M.; Idoeta, R. [The University of the Basque Country - UPV/EHU, Nuclear Engineering and Fluid Mechanics Dept. Faculty of Engineering, Alda. Urquijo 48013, Bilbao (Spain)

    2014-07-01

    As a result of caesium's and strontium's activity migration study developed in Spanish mainland soils, there has been obtained convective - diffusive migration equation that will reproduce adequately the movement that an activity deposit would follow in this land. Taking into account the dependence on rain that apparent convection velocity shows, it has been defined a new migration parameter that depends only on soil's properties. By means of a least square method and fitting the migration equation to experimental activity profiles, the values showed by the migration parameters in the studied soils, characteristics of that area, have been obtained. After that, there have been obtained the mean values of these parameters for each defined group that, depending on soil's texture, have been observed in the study performed about the movement of both radionuclides in soils and to whom these soils belong. Using these mean values and obtained equation, it has been properly reproduce those vertical activity profiles that were experimentally determined. In order to validate these values, a new sampling programme is carrying out in the north of Spain and, with obtained new sampling points' information, is going to verify if, indeed, obtained mean values also reproduce these new sampling points' activity vertical profile. (authors)

  18. Feeding ecology of mesopelagic zooplankton of the subtropical and subarctic North Pacific Ocean determined with fatty acid biomarkers

    Science.gov (United States)

    Wilson, S. E.; Steinberg, D. K.; Chu, F.-L. E.; Bishop, J. K. B.

    2010-10-01

    Mesopelagic zooplankton may meet their nutritional and metabolic requirements in a number of ways including consumption of sinking particles, carnivory, and vertical migration. How these feeding modes change with depth or location, however, is poorly known. We analyzed fatty acid (FA) profiles to characterize zooplankton diet and large particle (>51 ?m) composition in the mesopelagic zone (base of euphotic zone -1000 m) at two contrasting time-series sites in the subarctic (station K2) and subtropical (station ALOHA) Pacific Ocean. Total FA concentration was 15.5 times higher in zooplankton tissue at K2, largely due to FA storage by seasonal vertical migrators such as Neocalanus and Eucalanus. FA biomarkers specific to herbivory implied a higher plant-derived food source at mesotrophic K2 than at oligotrophic ALOHA. Zooplankton FA biomarkers specific to dinoflagellates and diatoms indicated that diatoms, and to a lesser extent, dinoflagellates were important food sources at K2. At ALOHA, dinoflagellate FAs were more prominent. Bacteria-specific FA biomarkers in zooplankton tissue were used as an indicator of particle feeding, and peaks were recorded at depths where known particle feeders were present at ALOHA (e.g., ostracods at 100-300 m). In contrast, depth profiles of bacterial FA were relatively constant with depth at K2. Diatom, dinoflagellate, and bacterial biomarkers were found in similar proportions in both zooplankton and particles with depth at both locations, providing additional evidence that mesopelagic zooplankton consume sinking particles. Carnivory indices were higher and increased significantly with depth at ALOHA, and exhibited distinct peaks at K2, representing an increase in dependence on other zooplankton for food in deep waters. Our results indicate that feeding ecology changes with depth as well as by location. These changes in zooplankton feeding ecology from the surface through the mesopelagic zone, and between contrasting environments, have important consequences for the quality and quantity of organic material available to deeper pelagic and benthic food webs, and for organic matter sequestration.

  19. Seasonal response of zooplankton to monsoonal reversals in the Arabian Sea

    Science.gov (United States)

    Smith, Sharon; Roman, Michael; Prusova, Irina; Wishner, Karen; Gowing, Marcia; Codispoti, L. A.; Barber, Richard; Marra, John; Flagg, Charles

    The US JGOFS Arabian Sea Process Study was designed to provide a seasonally and spatially resolved carbon budget for a basin exhibiting some of the highest and lowest concentrations of plant biomass in the world's ocean. During the US JGOFS Process Study in the Arabian Sea (September 1994-January 1996), the absolute maximum in biomass of epipelagic zooplankton in the entire study was observed during the Southwest Monsoon season inshore of the Findlater Jet in the area of upwelling. The greatest contrast between high and low biomass in the study area also was observed during the Southwest Monsoon, as was the strongest onshore-offshore gradient in biomass. Lowest biomass throughout the study was observed at the most offshore station (S15), outside the direct influence of the monsoon forcing. The greatest day/night contrasts in biomass were observed nearshore in all seasons, with nighttime biomass exceeding daytime in the Northeast Monsoon season, but daytime exceeding nighttime in the Southwest Monsoon season. The diel vertical migration patterns in general reversed between the monsoons at all stations in the southern part of the study area. Virtually, no diel vertical migration of zooplankton took place in any season at the station with strong, persistent subsurface suboxic conditions (N7), suggesting that these conditions suppress migration. Based on the distribution of biomass, we hypothesize that inshore of the Findlater Jet, zooplankton grazing on phytoplankton is the dominant pathway of carbon transformation during both monsoon seasons, whereas offshore the zooplankton feed primarily on microplankton or are carnivorous, conditions that result in reduction of the carbon flux mediated by the zooplankton. Predation by mesopelagic fish, primarily myctophids, may equal daily growth of zooplankton inshore of the Findlater Jet during all seasons. This suggests that the food web inshore of the Findlater Jet is well integrated, may have evolved during past periods of intensified upwelling, and has a distinctly annual cycle.

  20. Lateral and Vertical Vent Migration at Tecuitlapa Maar, Mexico

    Science.gov (United States)

    Ort, M. H.; Carrasco-Nunez, G.

    2006-12-01

    Tecuitlapa maar, in the Serdan-Oriental Basin, east-central Mexico, is 1.5 km diameter and 100 m deep. Reworked ash and lapilli (`toba cafe'), derived from surrounding volcanic highlands via eolian and fluvial processes, provided fluidized water-saturated sediment for fuel-coolant interactions. The eruption sequence begins with 1.5 2-m bedded tuff comprising 50% clast-supported accretionary-lapilli beds and 50% lapilli tuff of juvenile (basalt) and andesite lapilli in a mostly toba-cafe matrix. This grades into a lithic-rich breccia near the vent (east end of maar at this stage). Weakly bedded wet surge deposits complete unit I. Unit I is the finest of the sequence but has poor sorting and variable median grain size. Basaltic juvenile grains dominate (50-80%) and andesite and oxidized grains are subordinate. Unit II deposits are dune-bedded tuffs and 10-20-cm-thick basalt lapilli beds, with abundant lithic lapilli and bomb sags. Breccia beds coarsen (to 1-25 cm diam.), thicken (to 1-2 m), and become more lithic-rich (to 40%) upward, but tuff beds dominate. Matrices are mostly toba cafe ash. Average grain size of the matrix (-2 - -3 phi) coarsens in unit II and sorting improves. Andesitic and oxidized accidental lapilli increase upward, to 50%. Unit III is similar to unit II, but is less regularly bedded and is dominated by tuff breccias. 3-5-m sections alternate between more breccia-like and more tuff-like, but all are mixed in texture. 1-3-cm-thick accretionary lapilli beds are common. Unit III has the coarsest median grain size (-3 phi), slightly better sorting than lower units and components are similar to unit II. Unit IV is many 20-50-cm-thick open-framework basalt lapilli-breccia beds. The uppermost 2-3 m contain a few thin tuffs. Unit IV scoria resemble those at the cinder/spatter cones on the crater floor. Juvenile scoria dominate, but andesitic fine lapilli are 15-40% in the tuff layers. Tecuitlapa erupted from an E-W dike system. Facies analysis and impact-sag and duneform orientations show the vent migrated westward. Componentry changes may correlate with excavation and lateral migration into more andesite-rich toba cafe (fluvial deposits). Stratigraphic relations show that the drying-out phase produced scoria cones in a west-to-east direction.

  1. Zooplankton Distribution in Four Western Norwegian Fjords

    Science.gov (United States)

    Gorsky, G.; Flood, P. R.; Youngbluth, M.; Picheral, M.; Grisoni, J.-M.

    2000-01-01

    A multi-instrumental array constructed in the Laboratoire d'Ecologie du Plancton Marin in Villefranche sur mer, France, named the Underwater Video Profiler (UVP), was used to investigate the vertical distribution of zooplankton in four western Norwegian fjords in the summer 1996. Six distinct zoological groups were monitored. The fauna included: (a) small crustaceans (mainly copepods), (b) ctenophores (mainly lobates), (c) siphonophores (mainly physonects), (d) a scyphomedusa Periphylla periphylla, (e) chaetognaths and (f) appendicularians. The use of the non-disturbing video technique demonstrated that the distribution of large zooplankton is heterogeneous vertically and geographically. Furthermore, the abundance of non-migrating filter feeders in the deep basins of the fjords indicates that there is enough food (living and non-living particulate organic matter) to support their dietary needs. This adaptation may be considered as a strategy for survival in fjords. Specifically, living in dark, deep water reduces visual predation and population loss encountered in the upper layer due to advective processes.

  2. The role of zooplankton in the pelagic-benthic coupling of the Southern Ocean

    OpenAIRE

    Schnack-Schiel, Sigrid B.; Isla, Enrique

    2005-01-01

    Zooplankton contributes in different ways to pelagic-benthic coupling: Their faecal material is a major route of energy flow and the vertical migrations of many species as well as the production of pelagic larvae by benthic organisms represent different paths to link the two subsystems. Antarctic particle fluxes have been shown to be highly variable in size and composition within a given region and even at the same site from year to year. There are also differences throughout the water column...

  3. Depth-selection patterns and diel vertical migration of Daphnia ambigua (Crustacea: Cladocera) in lake El Plateado Patrones de selección de profundidad y migración vertical de Daphnia ambigua (Crustacea: Cladocera) en el lago El Plateado

    OpenAIRE

    RODRIGO RAMOS-JILIBERTO; LUIS R. ZÚÑIGA

    2001-01-01

    Eutrophic temperate and sub-tropical lakes often exhibit a marked vertical structure during the warm season that involves important spatial differences of physical, chemical and biological variables. Therefore, zooplankton is exposed to a highly heterogeneous environment in the vertical dimension. In this work, We analyze the depth-distribution of the cladoceran Daphnia ambigua in the eutrophic, monomictic lake El Plateado at midday and midnight, along with its relationship with the vertical ...

  4. Dynamic patterns of zooplankton transport and migration in Catuama Inlet (Pernambuco, Brazil), with emphasis on the decapod crustacean larvae / Patrones dinámicos de transporte y migración de zooplancton en el estuario Catuama (Pernambuco, Brasil), con énfasis en las larvas de crustáceos decápodos

    Scientific Electronic Library Online (English)

    Ralf, Schwamborn; Mauro de Meló, Júnior; Sigrid Neumann, Leitão; Werner, Ekau; Maryse Nogueira, Paranaguá.

    Full Text Available Esta investigación tiene como objetivo cuantificar y modelar el transporte de zooplancton, con énfasis en las larvas de Crustacea Decapoda. El muestreo se realizó a tres profundidades con una bomba de plancton acoplada a una red con malla de 300 /¿m. Se obtuvieron los datos de corrientes con un ADCP [...] . Los datos mostraron la existencia de campos de corrientes y de transporte vertical y horizontal heterogéneos. Se identificaron 27 grupos de Decapoda (larvas de Sergestidae, Porcellanidae, Upogebiidae, Caridea, Brachyura). La mayoría de las especies y fases larvales mostraron patrones de migración vertical característicos, en fase con los ciclos de la marea diurnos, favoreciendo la retención o exportación del estuario. Abstract in english The objective of this study was to quantify and to model zooplankton transport with emphasis on decapod crustacean larvae. Sampling was carried out at three depths with a plankton pump coupled to a 300-/¿m mesh. Current data were obtained with an ADCP. Our data showed the existence of vertically and [...] horizontally heterogeneous current and transport fields. We identified 27 groups of Decapoda (larvae of Sergestidae, Porcellanidae, Upogebiidae, Cari dea, Brachyura). Most of the species and larval phases showed characteristic vertical migration patterns, in phase with the diurnal tidal cycles, thus enhancing retention or export from the estuary.

  5. Dynamic patterns of zooplankton transport and migration in Catuama Inlet (Pernambuco, Brazil, with emphasis on the decapod crustacean larvae Patrones dinámicos de transporte y migración de zooplancton en el estuario Catuama (Pernambuco, Brasil, con énfasis en las larvas de crustáceos decápodos

    Directory of Open Access Journals (Sweden)

    Ralf Schwamborn

    2008-01-01

    Full Text Available The objective of this study was to quantify and to model zooplankton transport with emphasis on decapod crustacean larvae. Sampling was carried out at three depths with a plankton pump coupled to a 300-/¿m mesh. Current data were obtained with an ADCP. Our data showed the existence of vertically and horizontally heterogeneous current and transport fields. We identified 27 groups of Decapoda (larvae of Sergestidae, Porcellanidae, Upogebiidae, Cari dea, Brachyura. Most of the species and larval phases showed characteristic vertical migration patterns, in phase with the diurnal tidal cycles, thus enhancing retention or export from the estuary.Esta investigación tiene como objetivo cuantificar y modelar el transporte de zooplancton, con énfasis en las larvas de Crustacea Decapoda. El muestreo se realizó a tres profundidades con una bomba de plancton acoplada a una red con malla de 300 /¿m. Se obtuvieron los datos de corrientes con un ADCP. Los datos mostraron la existencia de campos de corrientes y de transporte vertical y horizontal heterogéneos. Se identificaron 27 grupos de Decapoda (larvas de Sergestidae, Porcellanidae, Upogebiidae, Caridea, Brachyura. La mayoría de las especies y fases larvales mostraron patrones de migración vertical característicos, en fase con los ciclos de la marea diurnos, favoreciendo la retención o exportación del estuario.

  6. Vertical Distribution of Daily Migrating Mesopelagic Fish in Respect to Nocturnal Lights

    KAUST Repository

    Prihartato, Perdana

    2014-12-01

    The nighttime distribution of vertically migrating mesopelagic fish in relation to nocturnal light was studied during a circumglobal survey, in the Red Sea, and in a fjord at high latitude. The study was based on data derived from ship borne echo sounders (circumglobal and the Red Sea) as well as using upward looking echo sounders mounted on the bottom (Masfjorden, Norway). We also applied a numerical model for analyzing diel vertical migration patterns. The effect of the lunar cycle was the focus in studies at low latitudes, while seasonal changes in nocturnal light climate was in focus at high latitude. Lunar phase significantly affected the distribution of mesopelagic fish at the global scale and in the Red Sea. During nights near full moon, scattering layers of mesopelagic fish distributed deeper than during darker phases of the moon. At high latitude, mesopelagic fish switched its behavior along with seasonal changes in nocturnal lights. In autumn, the population of the studied fish (Maurolicus mueleri) formed separated layers. Juveniles performed normal diel vertical migration followed by midnight sinking, with midnight sinking mainly related to temperature minima and also for avoiding predators. Meanwhile the adults did not migrate vertically, reducing foraging but increasing the adult survival. From late winter to mid-Spring, interrupted ascents behavior was noted in the afternoon. Predator avoidance, satiation, and finding temperature optimum might be the reason behind interrupted ascents. At lighter nights in mid-summer, M. muelleri took on schooling behavior, likely as an anti-predator behavior permitting access to the upper waters in the absence of darkness.

  7. Horizontal and vertical dynamics of zooplankton and larval fish communities during mid-summer in Disko Bay, West Greenland

    DEFF Research Database (Denmark)

    Munk, Peter; Nielsen, Torkel Gissel

    2015-01-01

    Disko Bay is a highly productive inlet at the border between high- and low-arctic sectors of west Greenland. The physical/chemical conditions in the bay have changed during recent decades, specifically during an inflow event in 1996–1997 that led to increased deep-water temperatures. To further understand the consequences of physical changes to the plankton community in the bay, we examine findings from a field study on mesozooplankton and fish larvae in the areas of Disko Bay and Disko Bank carried out in 1997. We sampled 31 stations over 5 days along four transects and assessed horizontal and vertical distribution patterns, community composition and plankton trophodynamics. Plankton abundance was enhanced near-coast and across the pycnocline, and communities differed between regions. Polar cod (Boreogadus saida) and the sandeel (Ammodytes sp.) were among the abundant fish larvae. Productivity/growth estimates of key species of copepods and fish larvae showed no apparent relationship to food availability; they reached weight specific values of ?6% day?1 for copepods and ?14% day?1 for fish larvae. Overall, we found a rich and dynamic plankton community, strongly influenced by the complex hydrography of the area. Thus, changes in physical characteristics of the bay could threaten the resilience of its ecosystem.

  8. Proximate control of diel vertical migration in Phyllosoma larvae of the Caribbean spiny lobster Panulirus argus.

    Science.gov (United States)

    Ziegler, Tracy A; Cohen, Jonathan H; Forward, Richard B

    2010-12-01

    Phyllosoma larvae of the spiny lobster Panulirus argus undergo diel vertical migration (DVM), in which they are at depth during the day and nearer the surface at night. This study determined the visual spectral sensitivity of Stage I larvae and investigated whether light plays a proximate role in DVM as an exogenous cue and as an entrainment cue for an endogenous rhythm in vertical migration. Under constant conditions, larvae have a circadian rhythm (24.5-h period) in vertical swimming that resulted in a twilight DVM pattern. The behavioral response spectrum and electroretinogram recording indicated two photoreceptor spectral classes with maxima at 360 and 486 nm. When stimulated in an apparatus that simulated the underwater angular light distribution, dark-adapted larvae showed only positive phototaxis, with a threshold intensity of 1.8 × 10(13) photons m(-2) s(-1) (3.0 × 10(-5) ?moles photons m(-2) s(-1)). They have an avoidance response to predator shadows in which they descend upon sudden decreases in light intensity of more than 69%. When stimulated with relative rates of decrease in light intensity as occur at sunset they ascended, whereas they descended upon relative rates of light intensity increase as occur at sunrise. Thus, the DVM pattern is controlled by both an endogenous circadian rhythm in swimming and behavioral responses to light at sunrise and sunset. PMID:21183442

  9. On the lateral migration of a slightly deformed bubble rising near a vertical plane wall

    CERN Document Server

    Sugiyama, Kazuyasu

    2010-01-01

    Deformation-induced lateral migration of a bubble slowly rising near a vertical plane wall in a stagnant liquid is numerically and theoretically investigated. In particular, our focus is set on a situation with a short clearance $c$ between the bubble interface and the wall. Motivated by the fact that numerically and experimentally measured migration velocities are considerably higher than the velocity estimated by the available analytical solution using the Fax\\'{e}n mirror image technique for $a/(a+c)\\ll 1$ (here $a$ is the bubble radius), when the clearance parameter $\\varepsilon(= c/a)$ is comparable to or smaller than unity, the numerical analysis based on the boundary-fitted finite-difference approach solving the Stokes equation is performed to complement the experiment. The migration velocity is found to be more affected by the high-order deformation modes with decreasing $\\varepsilon$. The numerical simulations are compared with a theoretical migration velocity obtained from a lubrication study of a n...

  10. UV B-induced vertical migrations of cyanobacteria in a microbial mat

    International Nuclear Information System (INIS)

    Exposure to moderate doses of UV B (0.35 to 0.79 W m-2 s-1 or 0.98 to 2.2 ?mol of photons m-2 s-1 at 310 nm) caused the surface layers of microbial mats from Solar Lake, Sinai, Egypt, to become visibly lighter green. Concurrent with the color change were rapid and dramatic reductions in gross photosynthesis and in the resultant high porewater oxygen concentrations in the surface layers of the mats. The depths at which both maximum gross photosynthesis and maximum oxygen concentrations occurred were displaced downward. In contrast, gross photosynthesis in the deeper layers of the mats increased in response to UV B incident upon the surface. The cessation of exposure to UV B partially reversed all of these changes. Taken together, these responses suggest that photoautotrophic members of the mat community, most likely the dominant cyanobacterium Microcoleus chthonoplastes, were migrating in response to the added UV B. The migration phenomenon was also observed in response to increases in visible radiation and UV A, but UV B was ca. 100-fold more effective than visible radiation and ca. 20-fold more effective than UV A in provoking the response. Migrating microorganisms within this mat are apparently able to sense UV B directly and respond behaviorally to limit their exposure to UV. Because of strong vertical gradients of light and dissolved substances in microbial mats, the migration and the resultant vertical redistribution of photosynthetic activity have important consequences for both the photobiology of the cyanobacteria and the net primary productivity of the mat ecosystem

  11. Vertical distribution and diel vertical migration of krill beneath snow-covered ice and in ice-free waters

    KAUST Repository

    Vestheim, Hege

    2013-11-11

    A bottom mounted upward looking Simrad EK60 120-kHz echo sounder was used to study scattering layers (SLs) and individuals of the krill Meganyctiphanes norvegica. The mooring was situated at 150-m depth in the Oslofjord, connected with an onshore cable for power and transmission of digitized data. Records spanned 5 months from late autumn to spring. A current meter and CTD was associated with the acoustic mooring and a shore-based webcam monitored ice conditions in the fjord. The continuous measurements were supplemented with intermittent krill sampling campaigns and their physical and biological environment.The krill carried out diel vertical migration (DVM) throughout the winter, regardless of the distribution of potential prey. The fjord froze over in mid-winter and the daytime distribution of a mid-water SL of krill immediately became shallower associated with snow fall after freezing, likely related to reduction of light intensities. Still, a fraction of the population always descended all the way to the bottom, so that the krill population by day seemed to inhabit waters with light levels spanning up to six orders of magnitude. Deep-living krill ascended in synchrony with the rest of the population in the afternoon, but individuals consistently reappeared in near-bottom waters already? 1 h after the ascent. Thereafter, the krill appeared to undertake asynchronous migrations, with some krill always being present in near-bottom waters even though the entire population appeared to undertake DVM. The Author 2013. Published by Oxford University Press. All rights reserved.

  12. Mathematical simulation of vertical migration of 137Cs and 134Cs in soil

    International Nuclear Information System (INIS)

    In the general case, simulation of radionuclide migration in soil reduces to a self-consistent description of the simultaneous process; exchange and nonexchange in adsorption, chemisorption, molecular adsorption, biological adsorption, diffusion of free and adsorbed ions, radionuclide transport during infiltration of atmospheric precipitation, transport of moisture in a capillary flow to the surface as a result of evaporation and under the influence of a temperature gradient, as well as transport to the root system of vegetation. The extent to which each of these processes affects the vertical distribution of radionuclides depends on the landscape and climatic conditions and is determined by a large number of factors characterizing the soil, local conditions, and physicochemical properties of radioactive fallout. The indeterminancy of many parameters affecting the radionuclide transport and the possibility of adsorption occurring by several interaction mechanisms simultaneously greatly hinder the use of the known laws of colloid and physical chemistry to describe the migration and absorption of radioactive substances. Considerable complexities are encountered in attempts to construct a model that would describe the infiltration and capillary flow of moisture with dissolved and suspended radioactive substances. By virtue of the universal laws of migration in soil, characteristic of both global fallout and fallout from the Chernobyl disaster complex mechanisms of migration can be described by a comparatively simple phenomenological model which, with a proper choice of parameters for the law, reflects the evolution of the radionuclide depth distribution in the soil layer. Such a model, the simplest versions of which were suggested back in the 1970s, is based on the use of the diffusion approximation to describe the migration of radioactive substances

  13. Inventory and vertical migration of 137Cs in Spanish mainland soils

    International Nuclear Information System (INIS)

    In this study the total activity of 137Cs deposited per unit area over the Spanish peninsular territory was analysed using a 150 x 150 km2 mesh grid, with samples taken from 29 points. The deposited activities ranged between 251 and 6074 Bq/m2. A linear relationship was obtained between these values and the mean annual rainfall at each sampling point which allowed a map to be drawn, using GIS software, which shows the distribution of total deposited 137Cs activity across the Spanish mainland. At twelve of these sampling points the vertical migration profile of 137Cs was obtained. These profiles are separated into two groups with different behaviour, one of which includes clay and loam soils and the other containing sandy soils. For both groups of profiles the parameters of the convective-diffusive model, which describes the vertical migration of 137Cs in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) were calculated. - Highlights: ? Measured the 137Cs activity in Spanish mainland, being within a range of [251, 6074] Bq/m2, with a mean value of 1726 Bq/m2. ? Establishment of the 137Cs background by means of a 137Cs inventory map showing its distribution in the Spanish mainland. ? 137Cs shows two different behaviour tendencies in soil depending on it. ? The parameters which govern the applied model have been obtained for the analysed profiles. ? Analysed those parameters, the two tendencies have been reflected in the obtained values.

  14. Type I Planet Migration in a Magnetized Disk. II. Effect of Vertical Angular Momentum Transport

    CERN Document Server

    Bans, Alissa; Uribe, Ana

    2015-01-01

    We study the effects of a large-scale, ordered magnetic field in protoplanetary disks on Type I planet migration using a linear perturbation analysis in the ideal-MHD limit. We focus on wind-driving disks, in which a magnetic torque $\\propto B_{0z} \\partial B_{0\\varphi}/\\partial z$ (where $B_{0z}$ and $B_{0\\varphi}$ are the equilibrium vertical and azimuthal field components) induces vertical angular momentum transport. We derive the governing differential equation for the disk response and identify its resonances and turning points. For a disk containing a slightly subthermal, pure-$B_{0z}$ field, the total 3D torque is close to its value in the 2D limit but remains lower than the hydrodynamic torque. In contrast with the 2D pure-$B_{0\\varphi}$ field model considered by Terquem (2003), inward migration is not reduced in this case when the field amplitude decreases with radius. The presence of a subdominant $B_{0\\varphi}$ component whose amplitude increases from zero at $z=0$ has little effect on the torque w...

  15. Zooplankton fecal pellets, marine snow, phytodetritus and the ocean's biological pump

    Science.gov (United States)

    Turner, Jefferson T.

    2015-01-01

    The 'biological pump' is the process by which photosynthetically-produced organic matter in the ocean descends from the surface layer to depth by a combination of sinking particles, advection or vertical mixing of dissolved organic matter, and transport by animals. Particulate organic matter that is exported downward from the euphotic zone is composed of combinations of fecal pellets from zooplankton and fish, organic aggregates known as 'marine snow' and phytodetritus from sinking phytoplankton. Previous reviews by Turner and Ferrante (1979) and Turner (2002) focused on publications that appeared through late 2001. Since that time, studies of the biological pump have continued, and there have been >300 papers on vertical export flux using sediment traps, large-volume filtration systems and other techniques from throughout the global ocean. This review will focus primarily on recent studies that have appeared since 2001. Major topics covered in this review are (1) an overview of the biological pump, and its efficiency and variability, and the role of dissolved organic carbon in the biological pump; (2) zooplankton fecal pellets, including the contribution of zooplankton fecal pellets to export flux, epipelagic retention of zooplankton fecal pellets due to zooplankton activities, zooplankton vertical migration and fecal pellet repackaging, microbial ecology of fecal pellets, sinking velocities of fecal pellets and aggregates, ballasting of sinking particles by mineral contents, phytoplankton cysts, intact cells and harmful algae toxins in fecal pellets, importance of fecal pellets from various types of zooplankton, and the role of zooplankton fecal pellets in picoplankton export; (3) marine snow, including the origins, abundance, and distributions of marine snow, particles and organisms associated with marine snow, consumption and fragmentation of marine snow by animals, pathogens associated with marine snow; (4) phytodetritus, including pulsed export of phytodetritus, phytodetritus from Phaeocystis spp., picoplankton in phytodetritus, the summer export pulse (SEP) of phytodetritus in the subtropical North Pacific, benthic community responses to phytodetritus; (5) other components of the biological pump, including fish fecal pellets and fish-mediated export, sinking carcasses of animals and macrophytes, feces from marine mammals, transparent exopolymer particles (TEP); (6) the biological pump and climate, including origins of the biological pump, the biological pump and glacial/interglacial cycles, the biological pump and contemporary climate variations, and the biological pump and anthropogenic climate change. The review concludes with potential future modifications in the biological pump due to climate change.

  16. Hydrothermal venting at endeavour ridge: effect on zooplankton biomass throughout the water column

    Science.gov (United States)

    Burd, Brenda J.; Thomson, Richard E.

    1994-09-01

    Bio-acoustical data reveal that the hydrothermal plume emanating from the main vent field near 2100 m depth on Endeavour Ridge (47°57'N, 129°06'W) affects the distribution and migration of zooplankton throughout the entire water column. Net samples taken in July of 1991 and 1992 show that the standing stock of macrozooplankton integrated over the water column was considerably higher within several kilometers of the main vent site than at locations tens of kilometers from the vent site. Community analysis reveals that there were distinct shallow (800 m depth) faunal assemblages in the vent region. Shallow fauna infiltrated the deep zooplankton acoustic scattering layers in the immediate vicinity of Endeavour Ridge, producing a mixed assemblage of animals, including large numbers of juvenile filter-feeding copepods and their predators that normally inhabit the shallow layer. In contrast, the deep acoustic scattering layers found 11 km to the southeast and 15 km to the north of the central vent field in 1991, and 50 km to the west of the central vent field in 1992, were composed of distinctly deep-sea fauna. The enhanced, vertically-integrated biomass over the vent region appears to result from vertical migration of zooplankton. A simple circulation model indicates that fauna can make the round-trip journey between the top of the plume and the upper ocean without being advected beyond the range of the detectable hydrothermal effluent.

  17. Long-term acoustical observations of the mesopelagic fish Maurolicus muelleri reveal novel and varied vertical migration patterns

    KAUST Repository

    Staby, A

    2011-11-15

    We studied the temporal dynamics in the vertical distribution of Maurolicus muelleri scattering layers (SL) by examining continuous acoustic recordings over a 15 mo period in Masfjorden, Norway, complemented by intermittent sampling campaigns. The data revealed known patterns as normal diel vertical migration (DVM), midnight sinking between dusk and dawn, and periods without migrations, as well as novel behaviours consisting of early morning ascents, reverse diel vertical migrations, and interrupted ascents in the evening. During the first autumn of the study, adult fish modified their normal DVM behaviour by suspending their migration in the evening, yet ascending toward the surface in the later part of the night to reach upper layers during dawn. This behaviour was not observed during the second autumn of the study. By mid- to end of November (1st autumn), adult fish had suspended the nocturnal ascent entirely, and in the subsequent period until the end of January, a fraction of the population rather performed limited reverse migrations, slightly shifting their vertical distribution upwards during the first part of the day. From January to March 2008, fish interrupted their evening ascent at apparently random intervals and returned to deeper waters, instead of completing a full ascent to the surface. Our study underlines the value of long-term recordings, with the results suggesting that M. muelleri has the capability of changing its behaviour in response to ontogeny and internal state (satiation and hunger) as well as to external stimuli.

  18. Providing food for zooplankton in the aboratory

    International Nuclear Information System (INIS)

    We are currently working in the laboratory with a species of zooplankton named Euphausiacea, but more commonly known as krill. This form of animal life is found abundantly in sea-water all over the world and serves as ideal food for numerous species of fish and cetaceans. Krill live in aggregates, often consisting of several thousand individuals, and migrate vertically each day; during the migration they feed, inter alia, on smaller crustaceans such as Copepoda. It is therefore highly instructive to study the part played by this form of animal life in the concentration and transport of radioactive substances in the sea. To make this possible, we have had to acclimatize the krill to laboratory conditions. In doing so many problems have been encountered, since it is a delicate creature and often difficult to keep alive. More specifically, one of our main worries has been to find food approximating as closely as possible the natural sustenance of Euphausiacea, food that is readily assimilable and relatively simple to procure. Artemia salina appeared to meet our requirements and we have begun rearing it on a mass scale

  19. Zooplankton and fisheries

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    Zooplankton are considered as the chief index of utilization of aquatic biotope at the secondary trophic level. The intensity of zooplankton aggregation depends on their ability to counter dispersion, phytoplankton growth, grazing rates, predator...

  20. Vertical migration of cryptosporidium parvum in unsaturated sand columns under transient flow conditions

    International Nuclear Information System (INIS)

    The objective of this study was to identify the effect of lag time and residual water saturation on the vertical migration of Cryptosporidium parvum oocysts under transient flow conditions experienced across vegetated filter strips (VFS) receiving runoff from livestock areas. The vertical migration of C. parvum oocysts through unsaturated soils was studied in laboratory sand columns. Approximately 1x105 C. parvum oocysts and 1x105 carboxylated latex microspheres (4.5 ?m diameter, Polysciences, Inc.) were applied to the top of sand columns at the beginning of each run. Transient water applications to the top of the sand columns (73 cm per hour) simulated an unusually high rate of pond overflow to the inlet area of a VFS after a large storm event, followed by a lag period of either 4 or 48 hours and a repeated water application. Residual water saturation conditions, during the lag period, were controlled to either 2.9 or 12.6 percent by applying a mild vacuum to the bottom of the sand column. The oocysts and microspheres were enumerated along the sand column profile using epifluorescence microscopy. The median travel distance for oocysts was 8.7 ± 1.1 cm at 12.6 percent residual saturation versus 6.7 ± 0.8 cm for 2.9 percent residual saturation. Lag time did not have a statistically significant effect on median travel distance. The study indicates that surface applied C. parvum oocysts have limited mobility through a uniform unsaturated sand medium experiencing high rates of transient water infiltration. (author)

  1. Vertical migration of cryptosporidium parvum in unsaturated sand columns under transient flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, T.; Mackert, S.D.; Graham, D.W. [Univ. of Kansas, Dept. of Civil, Environmental and Architectural Engineering, Lawrence, Kansas (United States)

    2002-06-15

    The objective of this study was to identify the effect of lag time and residual water saturation on the vertical migration of Cryptosporidium parvum oocysts under transient flow conditions experienced across vegetated filter strips (VFS) receiving runoff from livestock areas. The vertical migration of C. parvum oocysts through unsaturated soils was studied in laboratory sand columns. Approximately 1x10{sup 5} C. parvum oocysts and 1x10{sup 5} carboxylated latex microspheres (4.5 {mu}m diameter, Polysciences, Inc.) were applied to the top of sand columns at the beginning of each run. Transient water applications to the top of the sand columns (73 cm per hour) simulated an unusually high rate of pond overflow to the inlet area of a VFS after a large storm event, followed by a lag period of either 4 or 48 hours and a repeated water application. Residual water saturation conditions, during the lag period, were controlled to either 2.9 or 12.6 percent by applying a mild vacuum to the bottom of the sand column. The oocysts and microspheres were enumerated along the sand column profile using epifluorescence microscopy. The median travel distance for oocysts was 8.7 {+-} 1.1 cm at 12.6 percent residual saturation versus 6.7 {+-} 0.8 cm for 2.9 percent residual saturation. Lag time did not have a statistically significant effect on median travel distance. The study indicates that surface applied C. parvum oocysts have limited mobility through a uniform unsaturated sand medium experiencing high rates of transient water infiltration. (author)

  2. Zooplankton abundance, species composition and ecology of tropical high-mountain crater lake Wonchi, Ethiopia

    Directory of Open Access Journals (Sweden)

    Fasil Degefu

    2014-11-01

    Full Text Available The highlands of Ethiopia represent some of the remnants of undisturbed aquatic ecosystems; they are however highly threatened by significant socio–economic developments and associated anthropogenic impacts. Lake Wonchi is one of the few remaining fairly pristine high–mountain crater lakes in the central highlands and has never been investigated in detail. We present a first study on zooplankton taxa composition, abundance and biomass conducted over more than one year including the underlying environmental drivers. The lake is basic (pH 7.9-8.9, dilute (specific conductivity 185-245 µS cm-1 and oligotrophic with mean trophic status index of 36. The zooplankton community composition showed low species richness comprising a total of fourteen taxa with six cladocerans, one copepod and seven rotifers. Simpson´s index of diversity with values between 0.6 and 0.8 pointed towards a homogenous taxa occurrence within the single sample units. The overall mean (±SD standing biomass of zooplankton was 62.02±25.76 mg dry mass m-3,which is low compared to other highland and rift valley lakes in Ethiopia. Cyclopoid copepods, in particular Thermocyclops ethiopiensis were the most abundant group and contributed 50% to the total zooplankton abundance followed by cladocerans (38% and rotifers (12%. Non-metric multi-dimensional scaling resulted in a 3-dimensional model, which revealed similar community composition on successive sampling dates except in December/January and May. Temperature, alkalinity, conductivity and nitrate-N had significant influence on this seasonal pattern. A weak, but significant positive correlation (r=0.482, N=20, P=0.037 between Chlorophyll a and zooplankton biomass mirrors a bottom-up effect of phytoplankton biomass on zooplankton dynamics. The zooplankton of Lake Wonchi displayed some degree of segregation along the epi– and metalimnion during this study, but diel vertical migration was not observed. The results show that fish predation is not the key factor in structuring the vertical distribution of zooplankton in Lake Wonchi.

  3. Is vertical migration in Antarctic krill (Euphausia superba) influenced by an underlying circadian rhythm?

    Indian Academy of Sciences (India)

    Edward Gaten; Geraint Tarling; Harold Dowse; Charalambos Kyriacou; Ezio Rosato

    2008-12-01

    Antarctic krill (Euphausia superba) is a keystone species in the southern ocean ecosystem where it is the main consumer of phytoplankton and constitutes the main food item of many higher predators. Both food and predators are most abundant at the surface, thus krill hide in the depth of the ocean during the day and migrate to the upper layers at night, to feed at a time when the predatory risk is lowest. Although the functional significance of this diel vertical migration (DVM) is clear and its modulation by environmental factors has been described, the involvement of an endogenous circadian clock in this behaviour is as yet not fully resolved. We have analysed the circadian behaviour of Euphausia superba in a laboratory setting and here we present the first description of locomotor activity rhythms for this species. Our results are in agreement with the hypothesis that the circadian clock plays a key role in DVM. They also suggest that the interplay between food availability, social cues and the light:dark cycle acts as the predominant Zeitgeber for DVM in this species.

  4. Latitudinal comparisons of equatorial Pacific zooplankton

    Science.gov (United States)

    Roman, M. R.; Dam, H. G.; Le Borgne, R.; Zhang, X.

    Zooplankton biomass and rates of ingestion, egestion and production in the equatorial Pacific Ocean along 140°W and 180° exhibit maximum values in the High-Nutrient Low-Chlorophyll (HNLC) zone associated with equatorial upwelling (5°S-5°N) as compared to the more oligotrophic regions to the north and south. Zooplankton biomass and rates are not usually highest on the equator, but increase "downstream" of the upwelling center as the zooplankton populations exhibit a delayed response to enhanced phytoplankton production. The vertical distribution of zooplankton biomass in the equatorial HNLC area tends to be concentrated in surface waters and is more uniform with depth in oligotrophic regions to the north and south of the equatorial upwelling zone. In general, the amount of mesozooplankton (>200 ?m) carbon biomass is approximately 25% of estimated phytoplankton biomass and 30% of bacterial biomass in the HNLC area of the equatorial Pacific Ocean. Zooplankton grazing on phytoplankton is low in the equatorial Pacific Ocean, generally demand, it is apparent that zooplankton in the equatorial Pacific Ocean are omnivores, consuming primarily microzooplankton and detritus. Estimated zooplankton growth rates in the warm waters of the HNLC equatorial Pacific Ocean are high, ranging from 0.58 d -1 for 64-200 ?m zooplankton to 0.08 d -1 for 1000-2000 ?m zooplankton. Thus, the numerical and functional response of equatorial zooplankton to increases in phytoplankton production are more rapid than normally occurs in sub-tropical and temperate waters. Potential zooplankton fecal pellet production, estimated from metabolic demand, is approximately 1.6 times the estimated gravitational carbon flux at 150 m in the zone of equatorial upwelling (5°S-5°N) and 1.1 times the export flux in the more oligotrophic regions to the north and south. The active flux of carbon by diel migrant zooplankton in the HNLC zone is a minor fraction of the gravitational flux (2% at 140°W, 4% at 180°) but increases in the more oligotrophic regions to the north and south where there is a deeper mixed layer and a greater relative proportion of diel migrant zooplankton.

  5. Migrant biomass and respiratory carbon flux by zooplankton and micronekton in the subtropical northeast Atlantic Ocean (Canary Islands)

    Science.gov (United States)

    Ariza, A.; Garijo, J. C.; Landeira, J. M.; Bordes, F.; Hernández-León, S.

    2015-05-01

    Diel Vertical Migration (DVM) in marine ecosystems is performed by zooplankton and micronekton, promoting a poorly accounted export of carbon to the deep ocean. Major efforts have been made to estimate carbon export due to gravitational flux and to a lesser extent, to migrant zooplankton. However, migratory flux by micronekton has been largely neglected in this context, due to its time-consuming and difficult sampling. In this paper, we evaluated gravitational and migratory flux due to the respiration of zooplankton and micronekton in the northeast subtropical Atlantic Ocean (Canary Islands). Migratory flux was addressed by calculating the biomass of migrating components and measuring the electron transfer system (ETS) activity in zooplankton and dominant species representing micronekton (Euphausia gibboides, Sergia splendens and Lobianchia dofleini). Our results showed similar biomass in both components. The main taxa contributing to DVM within zooplankton were juvenile euphausiids, whereas micronekton were mainly dominated by fish, followed by adult euphausiids and decapods. The contribution to respiratory flux of zooplankton (3.4 ± 1.9 mg C m-2 d-1) was similar to that of micronekton (2.9 ± 1.0 mg C m-2 d-1). In summary, respiratory flux accounted for 53% (range 23-71) of the gravitational flux measured at 150 m depth (11.9 ± 5.8 mg C m-2 d-1). However, based on larger migratory ranges and gut clearance rates, micronekton are expected to be the dominant component that contributes to carbon export in deeper waters. Micronekton estimates in this paper as well as those in existing literature, although variable due to regional differences and difficulties in calculating their biomass, suggest that carbon fluxes driven by this community are important for future models of the biological carbon pump.

  6. A New Trait-Based Auto-Emergent Model for Zooplankton and Confrontation with Size-Structured Observations from the Bay of Biscay

    Science.gov (United States)

    Vandromme, Pieter; Sourisseau, Marc; Huret, Martin

    2013-04-01

    Zooplankton plays a significant role in marine ecosystems bridging the gap between primary producers and top consumers and interacting with the particle flux through complex dynamics. Scarcity of data and complexity of observing zooplankton make it difficult to integrate it in biogeochemical models where it is most often formulated in a simpler manner, i.e. classic box models with usually two compartments (micro and meso/macro zooplankton). Recent advances in automatic sizing, counting and identification allow better estimates of the dynamics and distribution of zooplankton, notably through the measurement of its size structure, and for zooplankton size matter. Most zooplankton physiological rates as well as predator:prey interactions can be significantly relied to individuals size through allometric relations. Such size-dependency was used in recent models. Yet, these models were neither confronted to observations nor integrated in 3D biogeochemical models. Here we propose a newly developed model of zooplankton dynamics based on size-dependent allometric relations but which allows various diet types regardless of the size. A size and a degree of herbivory is randomly drawn for each zooplankton species generated within the model (up to 400 here, limited by actual computational costs). By generating random degree of herbivory zooplankton species of same size could have various diet (from herbivore to carnivore). Other parameters leading to various reproductive strategies or vertical migration could also be drawn randomly (not tested here). The zooplankton model is coupled to the 3D biogeochemical model MARS3D on a test case representing a simplified view of the Bay of Biscay (i.e., continental shelf, estuary, tides). The model shows auto-emergent properties with the selection of size/diet most adapted to local conditions (here offshore vs. coastal, estuary…). Then, patterns of the modeled size-structure of the zooplankton are confronted to the ones observed during Spring-time cruises in the Bay of Biscay. The usefulness of the proposed zooplankton model for large scale biogeochemical models is further discussed.

  7. More active vertical migration of 137 Cs towards the groundwater level within areas of intensive agricultural activities

    International Nuclear Information System (INIS)

    Effect of agricultural pollutants upon the rate of 137 Cs migration in soil profiles has been studied. To estimate changes in the radiocaesium migration capacity with the presence of high amounts of potassic fertilizers were applied within experimental plots with podzolic and peat-boggy soils. The results of layer-by layer soil and ground testing within experimental and untreated (without KCL) plots were used to estimate an increase of the diffusion coefficient and 137 Cs migration rate in these soils in the period from June to September. Experimental results obtained suggest that the soil section enrichment with potassium provides a several times increase of radiocaesium vertical migration along soil profiles towards the groundwater level

  8. Diet of larvae and juvenile perch, Perca fluviatilis performing diel vertical migrations in a deep reservoir.

    Czech Academy of Sciences Publication Activity Database

    Kratochvíl, Michal; Peterka, Ji?í; Kube?ka, Jan; Mat?na, Josef; Vašek, Mojmír; Vaní?ková, I.; ?ech, Martin; Se?a, Jaromír

    2008-01-01

    Ro?. 57, ?. 3 (2008), s. 313-323. ISSN 0139-7893 R&D Projects: GA AV ?R(CZ) IAA600170502; GA AV ?R(CZ) 1QS600170504; GA ?R(CZ) GA206/06/1371 Institutional research plan: CEZ:AV0Z60170517 Keywords : 0+fish * Slapy Reservoir * digestive tracts fullness * zooplankton Subject RIV: EG - Zoology Impact factor: 0.522, year: 2008

  9. Diel vertical migrations of age 0+ percids in a shallow, well-mixed reservoir

    Directory of Open Access Journals (Sweden)

    Jaromír SE?A

    2010-08-01

    Full Text Available The distribution of age 0+ percids (perch, Perca fluviatilis and pikeperch, Sander lucioperca was investigated in a shallow, wellmixed reservoir during a 24-h period in late May, using acoustic and netting methods. Diel vertical migrations (DVMs were acoustically recorded between the layers close to the bottom and the whole water column. The netting data showed a high abundance of larvae and juveniles at night (nearly 1 ind m-3, or 6 ind m-2, whereas negligible numbers of age 0+ percids were present in the water column during the day (3% of night abundance. Age 0+ percids remained during the day in the layer very close to bottom. Smaller pikeperch larvae dominated the pelagic age 0+ fish assemblage during daylight, while larger perch prevailed at night. A strong difference between day and night abundances along with a clear pattern discerned by acoustic methods revealed the DVM of age 0+ percids. Analyses of the fish digestive tract contents indicate that DVM was not governed by feeding behaviour, but rather a defensive strategy against predation. This is in agreement with the size distribution of age 0+ percids, since they were smaller in water column during the day as opposed to the night.

  10. VERTICAL MIGRATION OF RADIONUCLIDES IN THE VICINITY OF THE CHERNOBYL CONFINEMENT SHELTER

    Energy Technology Data Exchange (ETDEWEB)

    Farfan, E.; Jannik, T.; Marra, J.

    2011-10-01

    Studies on vertical migration of Chernobyl-origin radionuclides in the 5-km zone of the Chernobyl Nuclear Power Plant (ChNPP) in the area of the Red Forest experimental site were completed. Measurements were made by gamma spectrometric methods using high purity germanium (HPGe) detectors with beryllium windows. Alpha-emitting isotopes of plutonium were determined by the measurement of the x-rays from their uranium progeny. The presence of {sup 60}Co, {sup 134,137}Cs, {sup 154,155}Eu, and {sup 241}Am in all soil layers down to a depth of 30 cm was observed. The presence of {sup 137}Cs and {sup 241}Am were noted in the area containing automorphous soils to a depth of 60 cm. In addition, the upper soil layers at the test site were found to contain {sup 243}Am and {sup 243}Cm. Over the past ten years, the {sup 241}Am/{sup 137}Cs ratio in soil at the experimental site has increased by a factor of 3.4, nearly twice as much as would be predicted based solely on radioactive decay. This may be due to 'fresh' fallout emanating from the ChNPP Confinement Shelter.

  11. Global fallout 137Cs accumulation and vertical migration in selected soils from South Patagonia

    International Nuclear Information System (INIS)

    The spatial distribution and vertical migration of global fallout 137Cs were studied in soils from South Patagonia at the austral region of South America in semi-natural and natural environments located between 50-54 deg. S and 68-74 deg. W. The 137Cs areal activity density varied from 222 to 858 Bq m-2, and was found to be significantly positively correlated (ps of 137Cs in the soil in such polar isotundra climate has been determined to be 0.056 cm y-1. This value is higher than vs determined under polar climate (-0.012 cm y-1) and is near to the upper limit of vs-values determined in temperate environments from Chile (0.019 cm y-1). The median value of the diffusion coefficient Ds (0.048 cm2 y-1) is similar to Ds observed in an Antarctic region (0.043 cm2 y-1) and lower than Ds in temperate regions of Chile (1.24 cm2 y-1). About 35 years after the highest depositions, 137Cs had penetrated to a depth of 6-14 cm in the Patagonian soils and can be expected to remain in the rooting zone of grass for many decades. Nevertheless, because of its low transfer to steppe grass observed at this region, the radioecological sensitivity of this ecosystem with respect to fallout radiocesium seems to be lower than in other polar regions

  12. Inter- and intra-specific diurnal habitat selection of zooplankton during the spring bloom observed by Video Plankton Recorder

    DEFF Research Database (Denmark)

    Sainmont, Julie; Gislason, Astthor

    2014-01-01

    Diel vertical migration (DVM) is a common behavior adopted by zooplankton species. DVM is a prominent adaptation for avoiding visual predation during daylight hours and still being able to feed on surface phytoplankton blooms during night. Here, we report on a DVM study using a Video Plankton Recorder (VPR), a tool that allows mapping of vertical zooplankton distributions with a far greater spatial resolution than conventional zooplankton nets. The study took place over a full day–night cycle in Disko Bay, Greenland, during the peak of the phytoplankton spring bloom. The sampling revealed a large abundance of copepods performing DVM (up during night and down during day). Migration behavior was expressed differently among the abundant groups with either a strong DVM (euphausiids), an absence of DVM (i.e., permanently deep; ostracods) or a marked DVM, driven by strong surface avoidance during the day and more variable depth preferences at night (Calanus spp.). The precise individual depth position provided by the VPR allowed us to conclude that the escape from surface waters during daytime reduces feeding opportunities but also lowers the risk of predation (by reducing the light exposure) and thereby is likely to influence both state (hunger, weight and stage) and survival. The results suggest that the copepods select day and night time habitats with similar light levels (~10?9 ?mol photon s?1 m?2). Furthermore, Calanus spp. displayed state-dependent behavior, with DVM most apparent for smaller individuals, and a deeper residence depth for the larger individuals.

  13. Evidence of vertical migration in the Ipanema bat Pygoderma bilabiatum (Chiroptera: Phyllostomidae: Stenodermatinae)

    OpenAIRE

    Carlos E. L. Esbérard; Isaac P. de Lima; Pedro H. Nobre; Althoff, Sérgio L.; Tássia Jordão-Nogueira; Daniela Dias; Fernando Carvalho; Marta E. Fabián; Margareth L. Sekiama; Artur Stanke Sobrinho

    2011-01-01

    Migration is defined as a seasonal and cyclic population movement observed in all animal classes and studied mainly in vertebrates. A considerable part of the knowledge on migration comes from birds, for which migration is an important aspect of their biology. In the case of bats, females usually migrate larger distances than males in some species. The present study analyzes the seasonal occurrence of Pygoderma bilabiatum (Wagner, 1843) at different elevations, in order to test for a pattern ...

  14. Vertical migration and dispersion of sprat ( Sprattus sprattus ) and herring ( Clupea harengus ) schools at dusk in the Baltic Sea

    DEFF Research Database (Denmark)

    Nilsson, Lars Anders Fredrik; Thygesen, Uffe Høgsbro; Lundgren, Bo; Nielsen, Bo Friis; Nielsen, J. Rasmus; Beyer, Jan

    2003-01-01

    In populations of herring (Clupea harengus) or sprat (Sprattus sprattus), one typically observes a pattern of schools forming at dawn and dispersing at dusk, usually combined with vertical migration. This behaviour influences interactions with other species; hence a better understanding of the processes could contribute to deeper insight into ecosystem dynamics. This paper reports field measurements of the dispersal at dusk and examines two hypotheses through statistical modelling: that the vert...

  15. Global fallout (137)Cs accumulation and vertical migration in selected soils from South Patagonia.

    Science.gov (United States)

    Schuller, P; Bunzl, K; Voigt, G; Ellies, A; Castillo, A

    2004-01-01

    The spatial distribution and vertical migration of global fallout (137)Cs were studied in soils from South Patagonia at the austral region of South America in semi-natural and natural environments located between 50-54 degrees S and 68-74 degrees W. The (137)Cs areal activity density varied from 222 to 858 Bq m(-2), and was found to be significantly positively correlated (pIslands (median 8%) and in other temperate environments in south-central Chile (median 0.2%). The median of the convection velocity v(s) of (137)Cs in the soil in such polar isotundra climate has been determined to be 0.056 cm y(-1). This value is higher than v(s) determined under polar climate (-0.012 cm y(-1)) and is near to the upper limit of v(s)-values determined in temperate environments from Chile (0.019 cm y(-1)). The median value of the diffusion coefficient D(s) (0.048 cm(2) y(-1)) is similar to D(s) observed in an Antarctic region (0.043 cm(2) y(-1)) and lower than D(s) in temperate regions of Chile (1.24 cm(2) y(-1)). About 35 years after the highest depositions, (137)Cs had penetrated to a depth of 6-14 cm in the Patagonian soils and can be expected to remain in the rooting zone of grass for many decades. Nevertheless, because of its low transfer to steppe grass observed at this region, the radioecological sensitivity of this ecosystem with respect to fallout radiocesium seems to be lower than in other polar regions. PMID:14557036

  16. Zooplankton from Lake Magelungen, Central Sweden 1960-1963

    International Nuclear Information System (INIS)

    The investigation of the zooplankton of Lake Magelungen, Central Sweden, was carried out over a period of three years. The aim of the investigation was to illustrate the qualitative and quantitative composition of the zooplankton before the release of waste water from the Aagesta Heat and Power Station began. Vertical sampling series were collected once a month at three different stations in the lake. The highest volumes of zooplankton were obtained in the summer. The ciliates predominated when the conditions were unfavourable for other zooplankton, as in winter just below the ice. The rotifers dominated during and immediately after the spring circulation. With one exception the crustaceans reached their peak volume values in August or September. The composition of the zooplankton indicates that Lake Magelungen is highly eutrophic

  17. Zooplankton from Lake Magelungen, Central Sweden 1960-1963

    Energy Technology Data Exchange (ETDEWEB)

    Almquist, Elisabeth

    1970-11-15

    The investigation of the zooplankton of Lake Magelungen, Central Sweden, was carried out over a period of three years. The aim of the investigation was to illustrate the qualitative and quantitative composition of the zooplankton before the release of waste water from the Aagesta Heat and Power Station began. Vertical sampling series were collected once a month at three different stations in the lake. The highest volumes of zooplankton were obtained in the summer. The ciliates predominated when the conditions were unfavourable for other zooplankton, as in winter just below the ice. The rotifers dominated during and immediately after the spring circulation. With one exception the crustaceans reached their peak volume values in August or September. The composition of the zooplankton indicates that Lake Magelungen is highly eutrophic

  18. 137Cs vertical migration in a deciduous forest soil following the Fukushima Dai-ichi Nuclear Power Plant accident

    International Nuclear Information System (INIS)

    The large amount of 137Cs deposited on the forest floor because of the Fukushima Dai-ichi Nuclear Power Plant accident represents a major potential long-term source for mobile 137Cs. To investigate 137Cs mobility in forest soils, we investigated the vertical migration of 137Cs through seepage water, using a lysimetric method. The study was conducted in a deciduous forest soil over a period spanning 2 month to 2 y after the Fukushima nuclear accident. Our observations demonstrated that the major part of 137Cs in the litter layer moved into the mineral soil within one year after the accident. On the other hand, the topsoil prevented migration of 137Cs, and only 2% of 137Cs in the leachate from litter and humus layer penetrated below a 10 cm depth. The annual migration below a 10 cm depth accounted for 0.1% of the total 137Cs inventory. Therefore, the migration of 137Cs by seepage water comprised only a very small part of the total 137Cs inventory in the mineral soil, which was undetectable from the vertical distribution of 137Cs in the soil profile. In the present and immediate future, most of the 137Cs deposited on the forest floor will probably remain in the topsoil successively, although a small but certain amount of bioavailable 137Cs exists in forest surface soil. -- Highlights: • Lysimeter captured 137Cs mobility in a forest soil after the Fukushima accident. • Major part of 137Cs in the litter layer moved into the mineral soil within a year. • Litter-leachate 137Cs was predominantly adsorbed within the topsoil. • The annual migration below a 10 cm depth was 0.1% of the total 137Cs inventory

  19. Assessment of brine migration risks along vertical pathways due to CO2 injection

    Science.gov (United States)

    Kissinger, Alexander; Class, Holger

    2015-04-01

    Global climate change, shortage of resources and the growing usage of renewable energy sources has lead to a growing demand for the utilization of subsurface systems. Among these competing uses are Carbon Capture and Storage (CCS), geothermal energy, nuclear waste disposal, 'renewable' methane or hydrogen storage as well as the ongoing production of fossil resources like oil, gas and coal. Additionally, these technologies may also create conflicts with essential public interests such as water supply. For example, the injection of CO2 into the subsurface causes an increase in pressure reaching far beyond the actual radius of influence of the CO2 plume, potentially leading to large amounts of displaced salt water. In this work we focus on the large scale impacts of CO2 storage on brine migration but the methodology and the obtained results may also apply to other fields like waste water disposal, where large amounts of fluid are injected into the subsurface. In contrast to modeling on the reservoir scale the spatial scale required for this work is much larger in both vertical and lateral direction, as the regional hydrogeology has to be considered. Structures such as fault zones, hydrogeological windows in the Rupelian clay or salt domes are considered as potential pathways for displaced fluids into shallow systems and their influence has to be taken into account. We put the focus of our investigations on the latter type of scenario, since there is still a poor understanding of the role that salt diapirs would play in CO2 storage projects. As there is hardly any field data available on this scale, we compare different levels of model complexity in order to identify the relevant processes for brine displacement and simplify the modeling process wherever possible, for example brine injection vs. CO2 injection, simplified geometries vs. the complex formation geometry and the role of salt induced density differences on flow. Further we investigate the impact of the displaced brine due to CO2 injection and compare it to the natural fluid exchange between shallow and deep aquifers in order to asses possible damage.

  20. Vertical migration of 85Sr, 137Cs and 131I in various arable and undisturbed soils.

    Czech Academy of Sciences Publication Activity Database

    Palágyi, Š.; Palágyiová, Jana

    2003-01-01

    Ro?. 257, ?. 2 (2003), s. 353-359. ISSN 0236-5731 Institutional research plan: CEZ:AV0Z1048901 Keywords : radionuclides migration * models of migration * soil profiles Subject RIV: DL - Nuclear Waste, Radioactive Pollution ; Quality Impact factor: 0.472, year: 2003

  1. Predator evasion in zooplankton is suppressed by polyunsaturated fatty acid limitation.

    Science.gov (United States)

    Brzezi?ski, Tomasz; von Elert, Eric

    2015-11-01

    Herbivorous zooplankton avoid size-selective predation by vertical migration to a deep, cold water refuge. Adaptation to low temperatures in planktonic poikilotherms depends on essential dietary lipids; the availability of these lipids often limits growth and reproduction of zooplankton. We hypothesized that limitation by essential lipids may affect habitat preferences and predator avoidance behavior in planktonic poikilotherms. We used a liposome supplementation technique to enrich the green alga Scenedesmus obliquus and the cyanobacterium Synecchococcus elongatus with the essential lipids, cholesterol and eicosapentaenoic acid (EPA), and an indoor system with a stratified water-column (plankton organ) to test whether the absence of these selected dietary lipids constrains predator avoidance (habitat preferences) in four species of the key-stone pelagic freshwater grazer Daphnia. We found that the capability of avoiding fish predation through habitat shift to the deeper and colder environment was suppressed in Daphnia unless the diet was supplemented with EPA; however, the availability of cholesterol did not affect habitat preferences of the tested taxa. Thus, their ability to access a predator-free refuge and the outcome of predator-prey interactions depends upon food quality (i.e. the availability of an essential fatty acid). Our results suggest that biochemical food quality limitation, a bottom-up factor, may affect the top-down control of herbivorous zooplankton. PMID:26232092

  2. Effect of plant trichomes on the vertical migration of Haemonchus contortus infective larvae on five tropical forages.

    Science.gov (United States)

    Oliveira, Aruaque L F; Costa, Ciniro; Rodella, Roberto A; Silva, Bruna F; Amarante, Alessandro F T

    2009-06-01

    The influence of trichomes on vertical migration and survival of Haemonchus contortus infective larvae (L3) on different forages was investigated. Four different forages showing different distributions of trichomes (Brachiaria brizantha cv. Marandu, Brachiaria brizantha cv. Xaraes, Andropogon gayanus, and Stylosanthes spp.), and one forage species without trichomes (Panicum maximum cv. Tanzania), were used. Forages cut at the post-grazing height were contaminated with faeces containing L3. Samples of different grass strata (0-10, 10-20, >20 cm) and faeces were collected for L3 quantification once per week over four weeks. In all forages studied, the highest L3 recovery occurred seven days after contamination, with the lowest recovery on A. gayanus. In general, larvae were found on all forages' strata. However, most of the larvae were at the lower stratum. There was no influence of trichomes on migration and survival of H. contortus L3 on the forages. PMID:18975119

  3. [Vertical Migration Characteristics of Organochlorine Pesticides in Overlying Soil in Karst Terranes and Its Impact on Groundwater].

    Science.gov (United States)

    Sun, Yu-chuan; Wang, Yong-qi; Liang, Zuo-bing; Yuan, Dao-xian

    2015-05-01

    Five soil profiles and four typical epikarst springs were selected in Nanchuan District, Chongqing Municipality as objects of the study on vertical migration of organochlorine pesticides (OCPs) in the soils and its impact on groundwater. OCPs in soil and epikarst spring water samples were quantitatively analyzed by gas chromatography. The results showed that HCHs and DDTs were detected in all the 5 soil profiles, varying in the range of 0.77-18.3 and 0.34-226 ng · g(-1), and averaging 5.16 and 16 ng · g(-1) in concentration, respectively. The highest concentrations of HCHs and DDTs were found in the subsoil (10-40 cm) in most sampling sites. The detection ratios of HCHs and DDTs in four springs were 100%. The concentrations of HCHs and DDTs fluctuated greatly in epikarst spring water during the one-year observation, and the concentration ranged from 2.09 to 60.1 and from N. D. to 79.8 ng · L(-1), with a mean value of 12 and 9.16 ng · L(-1), respectively. The concentrations of HCHs and DDTs in Hougou, Baishuwan and Lanhuagou spring in rainy season were all. higher than those in dry season in these three epikarst springs. There were no good corresponding relationship between HCHs and DDTs contents in spring water and those in corresponding spring catchment soil. TOC, soil water content, clay content and pH all inhibited the vertical migration of OCPs in Hougou spring catchment, which led to the lowest content of OCPs in spring water, although the OCPs content in Hougou spring catchment soils was the highest in the four spring catchments. However, the four factors didn't inhibit the vertical migration of OCPs in Shuifang spring catchment, which led to higher OCPs content in spring water, although the OCPs content in spring catchment soils was the lowest in the four spring catchments. PMID:26314106

  4. Zooplankton body composition

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2013-01-01

    I compiled literature on zooplankton body composition, from protozoans to gelatinous plankton, and report allometric relations and average body composition. Zooplankton segregate into gelatinous and non-gelatinous forms, with few intermediate taxa (chaetognaths, polychaetes, and pteropods). In most groups body composition is size independent. Exceptions are protozoans, chaetognaths, and pteropods, where larger individuals become increasingly watery. I speculate about the dichotomy in body compos...

  5. Marine zooplankton studies in Brazil: a brief evaluation and perspectives

    Directory of Open Access Journals (Sweden)

    Rubens M. Lopes

    2007-09-01

    Full Text Available Marine zooplankton research in Brazil has been primarily descriptive, with most studies focusing on community structure analysis and related issues. The composition and spatial distribution of several taxonomic groups are currently well known, although less-abundant and small-sized taxa as well as initial stages of almost all species have received little attention. Some numerically important taxa such as heterotrophic protists, ctenophores, acoel turbellarians and ostracods remain virtually unstudied. Large sectors of the continental shelf have not been sampled in detail, particularly those areas influenced by the North Brazil Current (5ºN-15ºS. Zooplankton abundance and biomass in offshore waters have seldom been quantified, and information on the distribution and vertical migration of meso- and bathypelagic species are lacking. Additional faunistic assessments must target those less-studied taxa and geographical locations. However, priority in ecological studies should be given to process-oriented investigations aimed at understanding the mechanisms controlling zooplankton distribution, trophic interactions within pelagic food webs and production cycles in relation to the physical environment. An effort should be made to incorporate state-of-the-art sampling technology and analytical methods into future research projects.As pesquisas sobre o zooplâncton marinho no Brasil têm sido primariamente descritivas, com a maioria dos estudos enfocando a análise da estrutura da comunidade e assuntos relacionados. A composição e a distribuição espacial de muitos grupos taxonômicos encontram-se bem estudadas, embora os táxons menos abundantes e de menores dimensões, assimcomo os estágios iniciais do ciclo de vida da maioria das espécies, tenham recebido pouca atenção. Alguns táxons numericamenteimportantes encontram-se pouco estudados, como no caso dos protistas heterotróficos, ctenóforos, turbelários acelos e ostrácodes. Amplos setores da plataforma continental não têm sido suficientemente amostrados, em particular nas áreas influenciadas pela Corrente Norte do Brasil (5ºN-15ºS. As áreas oceânicas têm sido também pouco estudadas e praticamente inexistem dados sobre a distribuição espacial e vertical das espécies meso- e batipelágicas. Levantamentos faunísticos adicionais devem focalizar os táxons e locais menos conhecidos. No entanto, sob o ponto de vista ecológico é necessário darprioridade a estudos de processos voltados ao entendimentodos mecanismos que governam a distribuição, as interações tróficas nas teias alimentares pelágicas e os ciclos de produção do zooplâncton em relação ao ambiente físico. Deve ser feito um esforço para incorporar novas tecnologias de amostragem e métodos analíticos em futuros projetos de pesquisa.

  6. Marine zooplankton studies in Brazil: a brief evaluation and perspectives

    Scientific Electronic Library Online (English)

    Rubens M., Lopes.

    2007-09-01

    Full Text Available As pesquisas sobre o zooplâncton marinho no Brasil têm sido primariamente descritivas, com a maioria dos estudos enfocando a análise da estrutura da comunidade e assuntos relacionados. A composição e a distribuição espacial de muitos grupos taxonômicos encontram-se bem estudadas, embora os táxons me [...] nos abundantes e de menores dimensões, assimcomo os estágios iniciais do ciclo de vida da maioria das espécies, tenham recebido pouca atenção. Alguns táxons numericamenteimportantes encontram-se pouco estudados, como no caso dos protistas heterotróficos, ctenóforos, turbelários acelos e ostrácodes. Amplos setores da plataforma continental não têm sido suficientemente amostrados, em particular nas áreas influenciadas pela Corrente Norte do Brasil (5ºN-15ºS). As áreas oceânicas têm sido também pouco estudadas e praticamente inexistem dados sobre a distribuição espacial e vertical das espécies meso- e batipelágicas. Levantamentos faunísticos adicionais devem focalizar os táxons e locais menos conhecidos. No entanto, sob o ponto de vista ecológico é necessário darprioridade a estudos de processos voltados ao entendimentodos mecanismos que governam a distribuição, as interações tróficas nas teias alimentares pelágicas e os ciclos de produção do zooplâncton em relação ao ambiente físico. Deve ser feito um esforço para incorporar novas tecnologias de amostragem e métodos analíticos em futuros projetos de pesquisa. Abstract in english Marine zooplankton research in Brazil has been primarily descriptive, with most studies focusing on community structure analysis and related issues. The composition and spatial distribution of several taxonomic groups are currently well known, although less-abundant and small-sized taxa as well as i [...] nitial stages of almost all species have received little attention. Some numerically important taxa such as heterotrophic protists, ctenophores, acoel turbellarians and ostracods remain virtually unstudied. Large sectors of the continental shelf have not been sampled in detail, particularly those areas influenced by the North Brazil Current (5ºN-15ºS). Zooplankton abundance and biomass in offshore waters have seldom been quantified, and information on the distribution and vertical migration of meso- and bathypelagic species are lacking. Additional faunistic assessments must target those less-studied taxa and geographical locations. However, priority in ecological studies should be given to process-oriented investigations aimed at understanding the mechanisms controlling zooplankton distribution, trophic interactions within pelagic food webs and production cycles in relation to the physical environment. An effort should be made to incorporate state-of-the-art sampling technology and analytical methods into future research projects.

  7. Habitat choice by marine zooplankton in a high-latitude ecosystem

    OpenAIRE

    Fossheim, Maria; Primicerio, Raul

    2008-01-01

    According to habitat choice theory, zooplanktonic prey should choose a depth habitat that maximizes food intake while minimizing predation risk. Body size affects competitive ability and vulnerability in zooplankton, thereby influencing the adaptive choice of depth habitat. To study sizedependent habitat choice in marine zooplankton, we sampled their vertical distributions on a finescale with an optical plankton counter (OPC) during a post-bloom condition in late spring on the continental she...

  8. Seasonal variation of zooplankton abundance, composition and biomass in the Chabahar Bay, Oman Sea

    OpenAIRE

    Neda Fazeli; Ahmad Savari; Seyed Mohamad Bagher Nabavi; Rasool Zare

    2013-01-01

    Temporal and spatial variation of zooplankton abundance, composition and biomass were examined on the Chabahar Bay, Oman Sea. The Chabahar Bay, a subtropical and semi-enclosed bay, provides an ideal breeding ground for many fish and shellfish. Five stations were investigated along the Bay. This area is under the influence of the Indian Ocean seasonal monsoons. Zooplankton was collected with vertical plankton tows using 100 µm mesh nets. Copepods dominated the zooplankton community followed by...

  9. Inventory and vertical migration of 90Sr fallout and 137Cs/90Sr ratio in Spanish mainland soils

    International Nuclear Information System (INIS)

    In this paper the inventory of 90Sr in 34 points distributed along the Spanish peninsular territory is presented. Obtained values range between 173 Bq/m2 and 2047 Bq/m2. From these data set and those 137Cs data obtained in a previous work the 137Cs/90Sr activity ratio has been established, laying this value between 0.9 and 3.6. Also the migration depth of both radionuclides has been analysed obtaining for 137Cs an average value 57% lower than that obtained for 90Sr. Additionally, this paper presents the results obtained in 11 sampling points in which the activity vertical profile has been measured. These profiles have been analysed to state the behaviour of strontium in soils and after, by using a convective-diffusive model, the parameters of the model which governs the vertical migration of 90Sr in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) have been evaluated. Mean values obtained are 0.20 cm/year and 3.67 cm2/year, respectively. - Highlights: ? Measured 90Sr activity in Spanish mainland, being within a range of [173, 2047] Bq/m2, with a mean value of 793 Bq/m2. ? Compared the migration capacity of 137Cs and 90Sr in the same soils. ? 90Sr shows a unique behaviour tendency in soil. ? The parameters which govern the applied model have been obtained for the analysed profiles. ? Analysed those parameters' values also reflects this unique tendency.

  10. Evidence of vertical migration in the Ipanema bat Pygoderma bilabiatum (Chiroptera: Phyllostomidae: Stenodermatinae)

    Scientific Electronic Library Online (English)

    Carlos E. L., Esbérard; Isaac P. de, Lima; Pedro H., Nobre; Sérgio L., Althoff; Tássia, Jordão-Nogueira; Daniela, Dias; Fernando, Carvalho; Marta E., Fabián; Margareth L., Sekiama; Artur Stanke, Sobrinho.

    2011-12-01

    Full Text Available Migration is defined as a seasonal and cyclic population movement observed in all animal classes and studied mainly in vertebrates. A considerable part of the knowledge on migration comes from birds, for which migration is an important aspect of their biology. In the case of bats, females usually mi [...] grate larger distances than males in some species. The present study analyzes the seasonal occurrence of Pygoderma bilabiatum (Wagner, 1843) at different elevations, in order to test for a pattern that evidences migration, using data from the states of Espírito Santo, Minas Gerais, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul, Brazil. A total of 529 specimens of P. bilabiatum were captured. Pygoderma bilabiatum seems to be more frequent at intermediate and high elevations (over 80% of all captures were made above 250 m a.s.l.) and at latitudes above 22°S, where rainfall is high (over 1,500 mm) and temperatures are mild (16-23°C). Sex ratio varied with elevation; it was skewed towards males at lower elevations (N = 9, r² = 0.60, F = 12.311, p = 0.008, Sex ratio = 0.0004*elevation + 0.976), though females predominated at all altitudinal bands and in all states analyzed.

  11. Seasonal migration, vertical activity and winter temperature experience of Greenland halibut Reinhardtius hippoglossoides (Walbaum) in West Greenland waters

    DEFF Research Database (Denmark)

    Boje, Jesper; Neuenfeldt, Stefan

    2014-01-01

    The deep-water flatfish Greenland halibut Reinhardtius hippoglossoides (Walbaum) is common along the West Greenland coast. In the northwestern fjords, Greenland halibut is an important socio-economic resource for the Greenland community, but due to the deep and partly ice-covered environment, very little is known about its behavior and habitat characteristics. We tagged adult Greenland halibut in the waters off Ilulissat with electronic data storage tags that collected information on depth, temperature, and time. Although clear differences between individuals in migration and vertical behavior were present, we discovered a consistent seasonal migration from the relatively shallow-water Disko Bay area into the deep waters of the Ilulissat Icefjord, where the fish resided in the winter months before returning to Disko Bay. Vertical activity was pronounced at both locations, with fish covering vertical distances of up to 100 m within 15 min. During the winter months, the fish experienced temperatures between ca.0 and 4°C, with most experiencing temperatures of 2 to 3°C. Irrespective of year and quarter of the year, the fish experienced warmer water and a broader range of temperatures when resident in Disko Bay (mean range 2.6°C) than when resident in the ice fjord (mean range 1.4°C). Using the tagged halibut as a 'live tool,' we show that parts of the ice fjord are hundreds of meters deeper than previously thought. We also document the first seawater temperature measurements made beneath the Jakobshavn Isbræ outlet glacier, revealing a positive relationship between depth and temperature for the upper 600 m and a between-year variation in temperatures beneath the ice sheet in 2001, 2002, and 2003

  12. Age-specific light preferences and vertical migration patterns of a Great Lakes invasive invertebrate, Hemimysis anomala

    Science.gov (United States)

    Boscarino, Brent T.; Halpin, Kathleen E.; Rudstam, Lars G.; Walsh, Maureen G.; Lantry, Brian F.

    2012-01-01

    We use a combination of spectral sensitivity analyses, laboratory behavioral observations and field distributions of a vertically migrating invertebrate, Hemimysis anomala (a recent invasive species to the Laurentian Great Lakes of North America), to determine if light preference and timing of emergence has an ontogenetic component. Juvenile Hemimysis (?3.4 and 10?2.4 mylux— a Hemimysis-specific unit of brightness derived from visual pigment analyses (wavelength of maximum absorbance = 500 nm; 1 mylux ~ 159 lx). These preferred light levels are equivalent to those present during nautical twilight on the Earth's surface and were several orders of magnitude brighter than those most preferred by adults (> 4.5 mm) in the laboratory (10?6.4 to 10?7.4 mylux). Both size classes completely avoided light levels of 10?0.4 mylux and greater, which are representative of daytime light levels at the Earth's surface. Net hauls taken at ~ 20-min intervals from sunset to the end of nautical twilight on two sampling occasions on Seneca Lake, New York (sampling depth = 2 m) revealed that juveniles emerged into the water column during civil twilight. Adult Hemimysis emerged later during nautical twilight when juveniles had already reached their maximum abundance in the water column. Laboratory-derived light preferences successfully predicted the timing of emergence and time of maximal abundance of both size classes on both sampling occasions. This study is one of the first to demonstrate that Hemimysis diel vertical migration has an ontogenetic component and to report the specific light levels likely to initiate and limit vertical movements.

  13. LONG-TERM DYNAMICS OF RADIONUCLIDE VERTICAL MIGRATION IN SOILS OF THE CHERNOBYL NUCLEAR POWER PLANT EXCLUSION ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Farfan, E

    2009-11-19

    The radioactive fallout from the Chernobyl Nuclear Power Plant (ChNPP) accident consisted of fuel and condensation components. An important radioecological task associated with the late phase of the accident is to evaluate the dynamics of radionuclide mobility in soils. Identification of the variability (or invariability) in the radionuclide transfer parameters makes it possible to (1) accurately predict migration patterns and biological availability of radionuclides and (2) evaluate long-term exposure trends for the population who may reoccupy the remediated abandoned areas. In 1986-1987, a number of experimental plots were established within various tracts of the fallout plume to assist with the determination of the long-term dynamics of radionuclide vertical migration in the soils. The transfer parameters for {sup 137}Cs, {sup 90}Sr, and {sup 239,240}Pu in the soil profile, as well as their ecological half-time of the radionuclide residence (T{sub 1/2}{sup ecol}) values in the upper 5-cm thick soil layers of different grasslands were estimated at various times since the accident. Migration characteristics in the grassland soils tend to decrease as follows: {sup 90}Sr > {sup 137}Cs {ge} {sup 239,240}Pu. It was found that the {sup 137}Cs absolute T{sub 1/2}{sup ecol} values are 3-7 times higher than its radioactive decay half-life value. Therefore, changes in the exposure dose resulting from the soil deposited {sup 137}Cs now depend only on its radioactive decay. The {sup 90}Sr T{sub 1/2}{sup ecol} values for the 21st year after the fallout tend to decrease, indicating an intensification of its migration capabilities. This trend appears consistent with a pool of mobile {sup 90}Sr forms that grows over time due to destruction of the fuel particles.

  14. Zooplankton community structure in a cyclonic and mode-water eddy in the Sargasso Sea

    Science.gov (United States)

    Eden, Bethany R.; Steinberg, Deborah K.; Goldthwait, Sarah A.; McGillicuddy, Dennis J., Jr.

    2009-10-01

    Mesoscale eddies are important suppliers of nutrients to the surface waters of oligotrophic gyres, but little is known about the biological response, particularly that of higher trophic levels, to these physical perturbations. During the summers of 2004 and 2005, we followed the development of a cyclonic eddy and an anti-cyclonic mode-water eddy in the Sargasso Sea. Zooplankton (>150 ?m) were collected across both eddies in 9 discrete depth intervals between 0 and 700 m. Comparison of the abundance of major taxa of mesozooplankton in the upper 150 m at eddy center and outside the eddies (day and night) indicated that the cyclone and mode-water eddy supported similar mesozooplankton communities, with several taxa significantly higher in abundance inside than outside the eddies, when compared with the Bermuda Atlantic Time-series Study site as representative of mean conditions. In both eddies copepod peak abundance occurred in the 50-100 m depth interval, coincident with the chlorophyll a maximum, suggesting elevated food concentration in the eddies may have influenced zooplankton vertical distribution. The two eddies differed in the strength of diel vertical migration of zooplankton, as indicated by the ratio of night:day abundance in the epipelagic zone, which was higher at the center of the mode-water eddy for most taxa. Over the sampling interval of 1-2 months, abundance of the three most common taxa (copepods, chaetognaths, and ostracods) decreased in the cyclone and increased in the mode-water eddy. This further supports previous findings that over the sampling period the cyclone was in a decay phase, while the mode-water eddy was sustaining nutrient fluxes and high phytoplankton concentrations. A more detailed analysis of community structure in the mode-water eddy indicated the 0-700 m integrated abundance of doliolids was significantly higher inside the mode-water eddy than outside. The presence of a mesopelagic (200-700 m) layer of lepadid barnacle cyprids in this eddy highlights the potential of eddies to transport and disperse biota. We conclude that when compared with average ambient conditions (as measured at BATS), mesoscale eddies can influence zooplankton behavior and alter zooplankton community structure which can affect food-web interactions and biogeochemical cycling in the open ocean.

  15. Zooplankton standing stock, community structure and diversity in the northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Srivastava, Y.

    The effects of large scale oil spill, which occurred during the Gulf War in 1991 on zooplankton standing stock, community structure and diversity in the northern Arabian Sea were studied. Surface (1-0 m) and vertical zooplankton hauls (200-0 m, 250...

  16. Vertical-cavity surface-emitting laser (VCSEL) sources for frequency domain photon migration

    Science.gov (United States)

    O'Sullivan, Thomas D.; No, Keun-Sik; Matlock, Alex; Hill, Brian; Cerussi, Albert E.; Tromberg, Bruce J.

    2015-03-01

    Frequency domain photon migration (FDPM) uses modulated laser light to measure the bulk optical properties of turbid media and is increasingly being applied for noninvasive functional medical imaging. Though semiconductor edge emitting laser diodes (EELs) have been traditionally used for this application, we show that VCSELs exhibit performance characteristics suitable for FDPM measurements of tissue optical properties. Their output power and modulation characteristics are more than sufficient for optical property recovery. In addition, their small size, high efficiency, low cost, and simple packaging make them an attractive choice as components in clinical FDPM systems. We demonstrate a unique, compact optical probe that was enabled by VCSEL technology.

  17. Soft-lubrication effect on the lateral migration of a slightly deformed bubble rising near a vertical plane wall

    CERN Document Server

    Sugiyama, Kazuyasu

    2008-01-01

    Deformation-induced lateral migration of a bubble slowly rising near a vertical plane wall in a stagnant liquid is numerically and theoretically investigated. In particular, our focus is set on a situation with a small clearance $c$ between the bubble interface and the wall. Motivated by the fact that experimentally measured migration velocity (Takemura et al. (2002, J. Fluid Mech. {\\bf 461}, 277)) is higher than the velocity estimated by the available analytical solution (Magnaudet et al. (2003, J. Fluid Mech. {\\bf 476}, 115)) using the Fax\\'{e}n mirror image technique for $\\kappa(=a/(a+c))\\ll 1$ (here $a$ is the bubble radius), when the clearance parameter $\\varepsilon(=c/a)$ is comparable to or smaller than unit, the numerical analysis based on the boundary-fitted finite-difference approach by solving the Stokes equation is performed to complement the experiment. To improve the understandings of a role of the squeezing flow within the bubble-wall gap, the theoretical analysis based on a soft-lubrication ap...

  18. Type I Planet Migration in a Magnetized Disk. I. Effect of Large-Scale Vertical and Azimuthal Field Components

    CERN Document Server

    Uribe, Ana; Königl, Arieh

    2015-01-01

    We study the effects of a large-scale, ordered magnetic field in protoplanetary disks on Type I planet migration using a combination of numerical simulations in 2D and 3D and a linear perturbation analysis. Steady-state models of such disks require the inclusion of magnetic diffusivity. To make progress using ideal MHD, we focus on simplified field configurations, involving purely vertical ($B_z$) and azimuthal ($B_\\varphi$) field components and a combination of the two. For each of the models we calculate the locations of the relevant resonances and of the turning points, which delineate the propagation regions of the MHD waves that transport angular momentum from the planet to the disk. We use both numerical and semianalytic methods to evaluate the cumulative back torque acting on the planet, and explore the effect of spatial gradients in the disk's physical variables on the results. We conclude that, under realistic (3D) circumstances, a large-scale magnetic field can slow down the inward migration that ch...

  19. Zooplankton of West Madagascar

    Science.gov (United States)

    Bemiasa, John; Remanevy, Sitraka

    2014-05-01

    During six week survey (August - October 2009) in Western and Northern coast of Madagascar, the R/V 'Dr. Fridtjof Nansen' has carried out a study of the pelagic ecosystem. In collaboration with Agulhas & Somali Current Large Marine Ecosystems project (ASCLME) and South West Indian Ocean Fisheries Project (SWIOFP), the aim of the survey was to establish the physical, chemical and biological characteristics of the Western Madagascar shelf region as a whole. Zooplankton samples were collected with Hydrobios Multinet at all environmental stations ranging from 200 m depth to the surface. The Multinet was equipped with 5 nets for depth-stratified sampling. The nets were fitted with 180 µm mesh size and the water flow through the nets was measured. The Multinet was deployed and retrieved at a rate of ~ 1.5 m per second and was obliquely hauled. The five nets were triggered at the pre-selected depth intervals 0-25m, 25-50m, 50-80m, 80-120m and 120-200m. All samples were stored in marked bottles and preserved with buffered formaldehyde of 4% for further analysis. As results,the zooplankton abundance was influenced by physico-chemical factors. During the study period 34 Family of zooplankton were identified which are dominated by Copepoda (58,69%) followed by Radiolaria (12,06%), Appendicularia (6,47%), Sagitta (5,11%), Larvae (4,57%), Ostracoda (3,13%), pelagic Foraminifera (2,15%). Family of zooplankton with abundance Madagascar.

  20. Abundancia estacional y distribución vertical del zooplancton gelatinoso carnívoro en una área de surgencia en el norte del Sistema de la Corriente de Humboldt Seasonal abundance and vertical distribution of the carnivorous gelatinous zooplankton in an upwelling area of the northern Humboldt Current System

    Directory of Open Access Journals (Sweden)

    Sergio Palma

    2004-01-01

    Full Text Available Se analizó la abundancia estacional y distribución vertical del zooplancton gelatinoso colectado en cuatro cruceros efectuados frente a la bahía de Mejillones. En esta zona se identificaron 44 especies macroplanctónicas distribuidas en 23 de sifonóforos, 17 de hidromedusas, y 4 de ctenóforos, de las cuales 8 especies, Sphaeronectes irregularis, Rhizophysa eysenhardti, Amphogona apicata, Proboscidactyla stellata, Sarsia coccometra, Pleurobrachia bachei, Thalassocalyce inconstans y Velamen parallelum, se registran por primera vez para el Sistema de la Corriente de Humboldt. Se determinó un incremento de abundancia en primavera y verano, con densas agregaciones (> 2.600 ind·100 m-3 en octubre de Aglaura hemistoma, Solmundella bitentaculata, Muggiaea atlantica y Pleurobrachia bachei, y en febrero de Obelia spp. Las mayores densidades se determinaron en la estación más costera y en el frente oceánico, mientras que en la estación oceánica se registró una fuerte disminución de abundancia. La mayoría de las especies dominantes se encontraron en los primeros 100 m de la columna de agua, con una mayor concentración de ejemplares en los primeros 25 o 50 m de profundidad. Esta distribución vertical estaría limitada por la capa de mínimo oxígeno (The seasonal abundance and vertical distribution of gelatinous zooplankton collected during four cruises off Mejillones bay were analyzed. In this area we identified 44 species of macroplankton distributed in 23 siphonophores, 17 hydromedusae, and 4 ctenophores. Eight species, Sphaeronectes irregularis, Rhizophysa eysenhardti, Amphogona apicata, Proboscidactyla stellata, Sarsia coccometra, Pleurobrachia bachei, Thalassocalyce inconstans and Velamen parallelum, are the first records in the Humboldt Current System. The seasonal distribution showed an increase in abundance in spring and summer, with the highest aggregations (> 2600 ind·100 m-3 of Aglaura hemistoma, Solmundella bitentaculata, Muggiaea atlantica and Pleurobrachia bachei in October and Obelia spp. in February. The highest densities were observed in the coastal station and in the oceanic front, while the oceanic station was characterized by a strong decrease in abundance. The vertical distribution showed that the most dominant species were founded in the first 100 m of the water column, with a higher concentration of organisms in the first 25 or 50 m of depth. This vertical distribution could be limited by presence of a minimum dissolved oxygen layer (< 1 ml·L-1 in shallow waters (30-50 m during de upwelling events

  1. Distribución vertical de la biomasa zooplanctónica y densidad ictioplanctónica durante un ciclo anual en la plataforma continental del sur del Golfo de México / Vertical distribution of zooplankton biomass and ichthyoplankton density during an annual cycle on the continental shelf of the southern Gulf of Mexico

    Scientific Electronic Library Online (English)

    María de la Luz, Espinosa-Fuentes; César, Flores-Coto; Laura, Sanvicente-Añorve; Faustino, Zavala-García.

    2009-08-01

    Full Text Available Se analizó estacionalmente la biomasa zooplanctónica (BZ) y la densidad ictioplanctónica (DI) en la columna de agua sobre la plataforma continental del sur del Golfo de México, para determinar sus patrones de distribución vertical y establecer si existe una relación entre ambos componentes. Se muest [...] rearon cinco niveles de profundidad: 0-6 m, 6-12 m, 12-18 m, 45-55 m y 95-105 m. El patrón de distribución vertical de la BZ y de la DI fue similar en todas las épocas de muestreo, con la mayor concentración de organismos en los niveles superficiales y la más baja en los niveles más profundos. Estos resultados sugieren que la columna de agua en el área de estudio puede estar dividida en una capa superficial (0 a 18 m) y una capa profunda (45 a 100 m) y que las diferencias estacionales pueden ser atribuidas a los procesos de mezcla. Esta diferencia entre las capas superficiales y las profundas ocurre porque, en general, las capas superficiales de la columna de agua son las más productivas. La relación entre la BZ y la DI fue positiva y significativa (ANCOVA, P Abstract in english Seasonal zooplankton biomass (ZB) and ichthyoplankton density (ID) in the water column on the continental shelf of the southern Gulf of Mexico were analyzed to determine their vertical distribution patterns and assess if there is a relationship between both components. Five depth levels were sampled [...] : 0-6, 6-12, 12-18, 45-55 and 95-105 m. The vertical distribution patterns of ZB and ID were similar for all sampling seasons, with the greatest concentration of organisms in the upper levels and the lowest at deeper levels. These results suggest that the water column in the study area may be divided into a surface layer (0-18 m) and a deep layer (45-100 m), and seasonal differences may be attributed to mixing processes. The difference between the surface and the deep layers occurs because, in general, the upper layer is the most productive sector of the water column. The relationship between ZB and ID in the water column was positive and significant (ANCOVA, P

  2. Habitat use and diel vertical migration of bigeye thresher shark: Overlap with pelagic longline fishing gear.

    Science.gov (United States)

    Coelho, Rui; Fernandez-Carvalho, Joana; Santos, Miguel N

    2015-12-01

    Pelagic longliners targeting swordfish and tunas in oceanic waters regularly capture sharks as bycatch, including currently protected species as the bigeye thresher, Alopias superciliosus. Fifteen bigeye threshers were tagged with pop-up satellite archival tags (PSATs) in 2012-2014 in the tropical northeast Atlantic, with successful transmissions received from 12 tags for a total of 907 tracking days. Marked diel vertical movements were recorded on all specimens, with most of the daytime spent in deeper colder water (mean depth = 353 m, SD = 73; mean temperature = 10.7 °C, SD = 1.8) and nighttime spent in warmer water closer to the surface (mean depth = 72 m, SD = 54; mean temperature = 21.9 °C, SD = 3.7). The operating depth of the pelagic longline gear was measured with Minilog Temperature and Depth Recorders (TDRs), and the overlap with habitat utilization was calculated. Overlap is taking place mainly during the night and is higher for juveniles. The results presented herein can be used as inputs for Ecological Risk Assessments for bigeye threshers captured in oceanic tuna fisheries, and serve as a basis for efficient management and conservation of this vulnerable shark species. PMID:26559889

  3. Influence of dinoflagellate diurnal vertical migrations on dimethylsulfoniopropionate and dimethylsulfide distribution and dynamics (St. Lawrence Estuary, Canada)

    Energy Technology Data Exchange (ETDEWEB)

    Merzouk, A.; Levasseur, M. [Laval Univ., Sainte-Foy, PQ (Canada). Dept. of Biology; Scarratt, M.; Michaud, S. [Fisheries and Oceans Canada, Maurice Lamontagne Inst., Mont Joli, PQ (Canada); Gosselin, M. [Quebec Univ., Rimouski, PQ (Canada). Institut des Sciences de la Mer de Rimouski

    2004-05-01

    Many biological processes control the production of climatically active dimethyl sulfide (DMS) in the ocean. Peaks in DMS often coincide with the collapse of algal blooms and the release of dimethylsulfoniopropionate (DMSP), the algal precursor of DMS. Large fluctuations in DMSP and DMS concentrations have been recently reported. While the cause for this is not well understood, it may be due to the vertical migration of dinoflagellates, physiological response to the light regime, and the impact of light on bacterial utilization of DMSP and DMS. This study, conducted in July 2000 in the lower St. Lawrence Estuary, gathered information on the influence of the diurnal migration of DMSP-rich dinoflagellates on the distribution and cycling of DMSP and DMS. A water mass with high concentration of Alexandrium tamarense and Scrippsiella trochoidea was localized through a series of short rosette casts. The water mass was marked and followed for 34 hours during calm conditions. Diel patterns were noted in particulate DMSP, dissolved DMSP and DMS with minimum concentrations during the night and maximum concentrations around noon. Similar diel variations were noted in DMSP-normalized to chlorophyll 'a', suggesting a light-induced de novo DMSP synthesis during the day. Accumulation of DMS around noon may be due to the physiological response of the algae and bacteria to light. Biological gross DMS production and bacterial DMS consumption were decoupled, resulting in prompt fluctuations in DMS. The study showed that DMS concentrations in DMSP-rich dinoflagellate systems containing DMSP lyases can vary by as much as a factor of 10 over a 24 hour period. 36 refs., 2 tabs., 7 figs.

  4. Vertical migration of gas through fractures due to salinity-buffered hydrate formation within the hydrate stability zone

    Science.gov (United States)

    Meyer, D.; Flemings, P. B.

    2014-12-01

    Seafloor gas vents within the hydrate stability zone along continental margins are frequently associated with high saturations of gas hydrate that increase upwards towards the seafloor (e.g. NGHP 01 Site 10A, UBGH2 Site 3, ODP Site 1249A). One model for how gas migrates through the hydrate stability zone proposes that salt exclusion during hydrate formation elevates the in-situ salinity, which allows for the coexistence of gas, hydrate, and water. In some portions of these sites, however, the hydrate saturations derived from pressure cores are insufficient to elevate the bulk salinity enough to induce three-phase conditions. Commonly, hydrate in these zones exists in individual, high-angle fractures within mudstone. An alternative gas migration model, applicable to fractured regions, proposes that the fractures act as highly permeable gas conduits for upward fluid flow. We present a model to describe gas flow and hydrate formation in these fractures. Hydrate begins forming at the fracture wall, where the components (water and gas) are available. Water is continuously drawn from the mudstone to the fracture by capillary forces. Due to hydrate formation, salinity is elevated to three-phase conditions at the fracture wall. Simultaneously, salt diffuses away from the fracture into the bounding mudstone. At this point, hydrate formation is controlled by the chemical diffusion of salt away from and the advection of less-saline water towards the fracture wall. Hydrate formation is ultimately limited by either insufficient water flow to the hydrate front or elevation of the bulk salinity to three-phase conditions. We explore the timescale, nature, and limitation of hydrate formation in vertical fractures.

  5. Diel vertical migration patterns in two populations of Chaoborus flavicans larvae (Diptera: Chaoboridae in response to fish kairomones

    Directory of Open Access Journals (Sweden)

    Takayuki HANAZATO

    2008-08-01

    Full Text Available Diel vertical migration (DVM of larvae of the phantom midge Chaoborus flavicans (Diptera: Chaoboridae inhabiting a fishless pond and a fish-abundant lake (Lake Nakanuma was studied in the field and in the laboratory. In the fishless pond, dissolved oxygen concentration and water temperature were homogeneously distributed in the vertical profiles and Chaoborus larvae did not show DVM. In contrast, there was thermal stratification and an anoxic layer in Lake Nakanuma, and 2nd, 3rd and 4th instar Chaoborus larvae exhibited DVM. Fourth instar Chaoborus larvae collected from the two populations were introduced into thermally stratified acrylic tubes containing 'fish water' (water conditioned by fish and containing only the fish 'smell' or control water free of fish smell after a two-day acclimatization, and the larval positions in the tubes were analysed during the day and at night. The two populations of Chaoborus larvae showed different DVM patterns in the control water: the larvae from Lake Nakanuma exhibited DVM, whereas those from the fishless pond did not. Chaoborus larvae from Lake Nakanuma responded to the fish kairomones, exhibiting marked DVM in the fish water, whereas little response to the fish smell was recognized in the larvae from the fishless pond. The presence of a difference in response between the two populations implies that they had genetically different patterns of expression of DVM and thus different behavioural responses to the fish smell. The fish smell tended to cause the Chaoborus larvae in the tubes to increase their depth, during both the day and night. The effects of the fish smell became ambiguous with time, suggesting microbial degradation of the fish kairomones.

  6. Assessment of vertical scar migration after classical abdominoplasty followed by lower abdominal flap fixation / Avaliação da migração vertical da cicatriz pós-abdominoplastia clássica com fixação do retalho abdominal inferior

    Scientific Electronic Library Online (English)

    Paul, Kaufmann; Luís Gustavo Moraes, Prado; Vinícius Volpe D' Angieri, Basile; Francesco, Mazzarone; Ivo, Pitanguy.

    2011-09-01

    Full Text Available INTRODUÇÃO: Na cirurgia plástica, uma constante preocupação é a cicatriz pós-operatória. É muito importante para o cirurgião conhecer a evolução natural da cicatriz. A cicatriz de abdominoplastia tem a tendência natural de subir com o passar do tempo. Neste estudo, calculou-se a migração vertical na [...] tural da cicatriz pós-abdominoplastia, avaliando o efeito da fixação do retalho abdominal inferior na prevenção dessa ascensão. MÉTODO: Estudo prospectivo e randomizado, realizado na 38ª Enfermaria da Santa Casa de Misericórdia do Rio de Janeiro durante o ano de 2010, incluindo 20 pacientes do sexo feminino com indicação de abdominoplastia, divididas em dois grupos, A e B, aleatoriamente. Nas pacientes do grupo A, foi realizada abdominoplastia clássica, segundo técnica preconizada pelo Prof. Ivo Pitanguy, e no grupo B foi incluída a fixação do retalho abdominal inferior por meio de sutura interessando a fáscia de Scarpa e a aponeurose do músculo reto abdominal. Duas semanas e seis meses após a cirurgia, foi medida a distância vertical em 16 pacientes, após aplicação dos critérios de exclusão, calculando-se a média de migração vertical e a diferença média entre os dois grupos. RESULTADOS: A diferença média de migração vertical ao longo de toda a cicatriz foi de 0,4 cm, sendo a média geral de migração nos grupo A (controle) e B (casos com fixação) de 1,06 cm e 0,68 cm, respectivamente. CONCLUSÕES: A cicatriz pós-abdominoplastia sofre migração vertical ao longo do tempo, sendo menor quando o retalho inferior é fixado. O cirurgião deve estar ciente da migração sofrida pela cicatriz para melhor planejamento da posição de sua incisão Abstract in english BACKGROUND: In plastic surgery, the postoperative scar is a frequent concern. It is very important for the surgeon to understand the natural evolution of the scar. The abdominoplasty scar has a natural tendency to move upwards over time. In this study, the extent of natural vertical scar migration a [...] fter abdominoplasty was calculated and the effect of fixing the lower abdominal flap to prevent this rise was assessed. METHODS: This prospective and randomized study was conducted at the 38th Nursing service of Santa Casa de Misericórdia do Rio de Janeiro, during 2010, and included 20 female patients with an indication for abdominoplasty. The patients were randomly divided into two groups, A and B. Classical abdominoplasty was performed in group A patients, according to the technique recommended by Prof. Ivo Pitanguy. Patients in group B also underwent lower abdominal flap fixation by suturing of Scarpa's fascia and the rectus abdominis muscle aponeurosis. At both two weeks and six months after surgery, the distance of vertical scar movement was measured in 16 patients after application of exclusion criteria. The average vertical migration and the mean difference between the groups were calculated. RESULTS: The average difference between the groups in vertical migration throughout the scar was 0.4 cm, with a mean overall migration of 1.06 cm and 0.68 cm in groups A (control group) and B (cases with fixation), respectively. CONCLUSIONS: The scar formed after abdominoplasty undergoes vertical migration over time; this migration is decreased when the lower abdominal flap is fixed. The surgeon should be aware of scar migration for better planning of the incision location

  7. Migraciones verticales de Alexandrium excavatum (Braarud) Balech et Tangen en columnas experimentales / Vertical migration of Alexandrium excavatum (Braaruud) Balech et Tangen in experimental columns

    Scientific Electronic Library Online (English)

    Betina Andrea, Santos; Jose Ignacio, Carreto.

    Full Text Available As migrações verticais nicterais do dinoflagelado Alexandrium excavatum, foram observadas em uma coluna de vidro (50 cm de altura e 8 cm de diâmetro), durante um ciclo de 14 horas de luz/10 horas de escuro. As amostras foram tomadas a cada 2 ou 3 horas em superfície, meio e fundo. Verificou-se que o [...] s organismos de A. excavatum se agregam em superfície durante o dia e descem à noite. Os efeitos da estratificação da temperatura e exaustão dos nutrientes sobre o padrão da migração vertical foram examinados. A presença da termoclina de 6ºC retardou o movimento de migração. A deficiência do nitrogênio na camada superior da cultura antecipou a migração dos organismos em direção ao fundo, durante o dia; a adição de nitrato à camada de fundo antecipou a migração em direção à superfície, durante a noite. A velocidade de absorção do nitrato, no escuro, por células deficientes em nitrogênio, foi determinada a partir da diminuição da concentração desse nutriente na cultura. A taxa de absorção de nitrato foi elevada durante a primeira hora, decresceu nas três horas seguintes e foi nula a seguir. Sugere-se que a habilidade de A excavatum para absorver nitrato no período de escuro, juntamente com a migração vertical, possam ser mecanismos que regulem o seu florescimento. Abstract in spanish [...] Abstract in english Diel vertical migrations of the marine dinoflagellate A excavatum were followed in a laboratory water column, and the effects of temperature stratification and nitrogen depletion on patterns of migration were examined. It was found that A. excavatum is a vertical migrator aggregating at surface duri [...] ng daylight, and descending at night. A six-degree thermocline did not restrict its migration but delayed the vertical movements. Nitrogen depletion in the culture was correlated with earlier downward migration in the day, and nitrate assimilation in the dark was confirmed. In another essay, with a nitrogen deficient culture, nocturnal nitrate uptake per cell was measured. It is suggested that the ability of A. excavatum to take up nitrate in the dark working together with diurnal vertical migration could be important mechanisms regulating bloom developments.

  8. Effects of nitrate on the diurnal vertical migration, carbon to nitrogen ratio, and the photosynthetic capacity of the dinoflagellate Gymnodinium splendens

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, J.J.; Horrigan, S.G.

    1981-01-01

    A non-thecate dinoflagellate, Gymnodinium splendens, was studied in a 12 d laboratory experiment in 2.0 x 0.25 m containers in which light, temperature, and nutrients could be manipulated. Under a 12 h light:12 h dark cycle, the dinoflagellates exhibited diurnal vertical migrations, swimming downward before the dark period began and upward before the end of the dark period. This vertical migration probably involved geotaxis and a diel rhythm, as well as light-mediated behavior. The vertical distribution of nitrate affected the behavior and physiology of the dinoflagellate. When nitrate was present throughout the container, the organisms resembled those in exponential batch culture both in C:N ratios and photosynthetic capacity (P/sub max/); moreover, they migrated to the surface during the day. In contrast, when nitrate was depleted, C:N ratios increased, P/sub max/ decreased, and the organisms formed a subsurface layer at a depth corresponding to the light level at which photosynthesis saturated. When nitrate was present only at the bottom of the tank, C:N ratios of the population decreased until similar to those of nutrient-saturated cells and P/sub max/ increased; however, the dinoflagellates behaved the same as nutient-depleted cells, forming a subsurface layer during the light period. Field measurements revealed a migratory subsurface chlorophyll maximum layer dominated by G. splendens. It was just above the nitracline during the day, and in the nitracline during the night, which concurs with our laboratory observations.

  9. Statistical Mechanics of Zooplankton.

    Science.gov (United States)

    Hinow, Peter; Nihongi, Ai; Strickler, J Rudi

    2015-01-01

    Statistical mechanics provides the link between microscopic properties of many-particle systems and macroscopic properties such as pressure and temperature. Observations of similar "microscopic" quantities exist for the motion of zooplankton, as well as many species of other social animals. Herein, we propose to take average squared velocities as the definition of the "ecological temperature" of a population under different conditions on nutrients, light, oxygen and others. We test the usefulness of this definition on observations of the crustacean zooplankton Daphnia pulicaria. In one set of experiments, D. pulicaria is infested with the pathogen Vibrio cholerae, the causative agent of cholera. We find that infested D. pulicaria under light exposure have a significantly greater ecological temperature, which puts them at a greater risk of detection by visual predators. In a second set of experiments, we observe D. pulicaria in cold and warm water, and in darkness and under light exposure. Overall, our ecological temperature is a good discriminator of the crustacean's swimming behavior. PMID:26270537

  10. Sobre a migração vertical diária do plâncton ao largo de Santos, Estado de São Paulo, Brasil / On the diurnal vertical migration of plankton off the coast of Santos, São Paulo State, Brazil

    Scientific Electronic Library Online (English)

    Gloria Soares, Moreira.

    Full Text Available Várias estações foram ocupadas ao largo de Santos, durante os anos de 1960, 1961 e 1962, com a finalidade do estudo da migração vertical diária do plâncton, assim como sua relação com os parâmetros temperatura, salinidade e massas de água. Os quadros gerais do movimento vertical variaram nas diferen [...] tes datas. Demonstrou-se que a luz nem sempre pôde ser considerada como o principal fator envolvido na migração. A termoclina atuou como um fator limitando o movimento em apenas uma, das cinco estações onde esteve presente. Em estações onde ocorreram massas de água de diferentes limites de salinidade, a migração dos zooplanctontes ocorreu em geral acima ou abaixo da região de encontro dessas massas de água, independente da presença ou não de termoclina. Concluiu-se que, na região onde os estudos foram feitos, a migração diária do plâncton se apresenta bastante diversificada e não pode ser diretamente relacionada a diferentes épocas do ano ou condições oceanográficas predominantes na região. Este fato deve ser levado em conta em futuros estudos de distribuição e ecologia na região, assim como, nos resultados obtidos nos estudos de indicadores planctônicos. Abstract in english Several stations were occupied off the coast of Santos, with the purpose of studying the diurnal vertical migration of plankton. The results showed that in the region, the patterns of migration of net plankton are quite diversified and they cannot be related to differ ent seasons or oceanographie pa [...] rameters.

  11. Distribution and vertical dynamics of planktonic communities at Sofala Bank, Mozambique

    Science.gov (United States)

    Leal, M. C.; Sá, C.; Nordez, S.; Brotas, V.; Paula, J.

    2009-10-01

    Coastal ecosystem processes are largely influenced by the interaction of different factors operating at various temporal and spatial scales, specifically those responsible for primary production patterns that modulate zooplankton and subsequent trophic levels. Hydrological processes, such as tidal cycles and coastal currents, nutrients availability, phytoplankton groups (studied through algal pigment signatures analysed by HPLC), and zooplankton abundance and distribution were investigated at the Sofala Bank (Mozambique), with special emphasis on their horizontal distribution and vertical dynamics (48 h). Horizontal distribution has shown inshore-offshore gradients in all analysed parameters, as well as inshore waters intrusion probably related to Zambezi River delta runoff. Tidal currents were responsible for major hydrological vertical variations and for horizontal and vertical advection of phytoplankton biomass in the surface and deepest layers, respectively. Nutrient concentrations were typical from oligotrophic regions, and nutrient ratios were strongly influenced by depleted nitrate + nitrite concentrations, indicating low estuarine discharges typical from the dry season. The very low N:P ratio obtained suggests strong nitrogen limitation to phytoplankton communities, supporting the low phytoplankton abundance observed. Both phytoplankton pigments and zooplankton were found mainly near the bottom (40 m depth), despite the latter displayed vertical migrations triggered by light variations. Phytoplankton community was dominated by microflagellates, specifically prymnesiophyceans, and behaved as a whole, except Cyanobacteria that displayed vertical distribution movements different from other phytoplankton groups, being mainly concentrated at mid-water column depths (10-20 m). This investigation enhances physico-chemical phenomena and their importance determining the planktonic communities vertical dynamics at Sofala Bank, a tropical coastal ecosystem of the Western Indian Ocean where planktonic dynamics are still poorly described and understood.

  12. Effect of Water Hyacinth (Eichornia crassippes) Infestation on Zooplankton Populations in Awba Reservoir, Ibadan South-West Nigeria

    OpenAIRE

    K.S. Chukwuka; U.N. Uka

    2007-01-01

    The effects of water hyacinth infestation on the distribution, abundance and species composition of zooplankton in Awba reservoir were investigated. Samples were collected in each of the sampling areas (water hyacinth infested and open water) by vertical zooplankton hauls using 64 um bolting silk net. The samples were immediately fixed in 4% formalin for preservation. The species composition of the zooplankton from the sampled areas consisted of 3 taxa, comprising of 6 species of Cladocera (M...

  13. Seasonal variation of zooplankton abundance, composition and biomass in the Chabahar Bay, Oman Sea

    Directory of Open Access Journals (Sweden)

    Neda Fazeli

    2013-12-01

    Full Text Available Temporal and spatial variation of zooplankton abundance, composition and biomass were examined on the Chabahar Bay, Oman Sea. The Chabahar Bay, a subtropical and semi-enclosed bay, provides an ideal breeding ground for many fish and shellfish. Five stations were investigated along the Bay. This area is under the influence of the Indian Ocean seasonal monsoons. Zooplankton was collected with vertical plankton tows using 100 µm mesh nets. Copepods dominated the zooplankton community followed by larvacea, cladocera and chaetognatha. Fifteen taxa of zooplankton were identified. Oithona nana and Euterpina acutifrons were dominated in the whole year and Larvacea showed a bloom in Northeast Monsoon. A Two-way ANOVA indicated that there were differences in abundance and biomass between sampling periods and between stations were significant. The peak zooplankton abundance in NE Monsoon could be due to winter cooling, with entrainment of nutrients into the upper layer producing phytoplankton blooms. The decline of zooplankton abundance and biomass in South West Monsoon and post-monsoon could be explained by decrease in chlorophyll a concentrations. The present result showed the composition and distribution of zooplankton differed between the monsoon seasons, resulted from changes in hydrographic conditions.

  14. Zooplankton interactions with the oxygen minimum zone in the eastern south pacific / Interacciones del zooplancton con la zona de mínimo oxigeno en el Pacífico sur oriental

    Scientific Electronic Library Online (English)

    Rubén, Escribano.

    2006-10-01

    Full Text Available El zooplancton de la zona de surgencia costera en el Pacífico Sur Oriental se encuentra afecto a una zona de mínimo de oxígeno muy somera (ZMO). En el presente trabajo, se resume la información disponible de las especies del zooplancton que interactuan con la ZMO en la región de surgencia del norte [...] de Chile. Los datos provienen desde los cruceros MinOx y ZOMEI realizados en marzo del 2000 y octubre del 2005, respectivamente a bordo del R/V Vidal Gormáz de la Armada de Chile. Cerca de 19 especies de copépodos y 10 de eufáusidos se analizaron en su distribución vertical y conducta migratoria. Varias especies abundantes se encuentran restringidas por la ZMO a la capa superior de 50 m. Sin embargo, otras especies abundantes habitan temporal o permanentemente la ZOM, contribuyendo sustancialmente al flujo vertical de C producido en la zona fótica a través de la migración vertical activa. La dinámica poblacional y las estrategias de los ciclos de vida, así como las adaptaciones metabólicas de las distintas especies, pueden no solo modular la contribución de ellas a los flujos verticales de C, sino que además a la mantención y persistencia de la masa de agua deficiente en oxígeno. Abstract in english Zooplankton in the coastal upwelling zone off the eastern South Pacific must cope with a shallow oxygen minimum zone. In this work, I summarize available information on the zooplankton species that interact with the OMZ in the upwelling region off northern Chile. Data are available from the MinOx cr [...] uise carried out in March 2000 and the ZOMEI cruise perfomed in October 2005, both onboard the R/V Vidal Gormaz of the Chilean navy. Nineteen species of copepods and 10 of euphausiids were analyzed in their vertical distribution and migrating behavior. Several abundante species appeared constrained by the OMZ and restricted to the upper 50m layer. However, other abundant species inhabit temporarily or permanently the OMZ contributing substantially to the vertical flux of C produced in the photic zone through active vertical migration. Population dynamics and life cycle strategies, as well as metabolic adaptations of the species, may not only modulate their contributions to vertical fluxes of C, but also to the maintenance and persistence of the oxygen-depleted water mass.

  15. Zooplankton interactions with the oxygen minimum zone in the eastern south pacific Interacciones del zooplancton con la zona de mínimo oxigeno en el Pacífico sur oriental

    Directory of Open Access Journals (Sweden)

    Rubén Escribano

    2006-10-01

    Full Text Available Zooplankton in the coastal upwelling zone off the eastern South Pacific must cope with a shallow oxygen minimum zone. In this work, I summarize available information on the zooplankton species that interact with the OMZ in the upwelling region off northern Chile. Data are available from the MinOx cruise carried out in March 2000 and the ZOMEI cruise perfomed in October 2005, both onboard the R/V Vidal Gormaz of the Chilean navy. Nineteen species of copepods and 10 of euphausiids were analyzed in their vertical distribution and migrating behavior. Several abundante species appeared constrained by the OMZ and restricted to the upper 50m layer. However, other abundant species inhabit temporarily or permanently the OMZ contributing substantially to the vertical flux of C produced in the photic zone through active vertical migration. Population dynamics and life cycle strategies, as well as metabolic adaptations of the species, may not only modulate their contributions to vertical fluxes of C, but also to the maintenance and persistence of the oxygen-depleted water mass.El zooplancton de la zona de surgencia costera en el Pacífico Sur Oriental se encuentra afecto a una zona de mínimo de oxígeno muy somera (ZMO. En el presente trabajo, se resume la información disponible de las especies del zooplancton que interactuan con la ZMO en la región de surgencia del norte de Chile. Los datos provienen desde los cruceros MinOx y ZOMEI realizados en marzo del 2000 y octubre del 2005, respectivamente a bordo del R/V Vidal Gormáz de la Armada de Chile. Cerca de 19 especies de copépodos y 10 de eufáusidos se analizaron en su distribución vertical y conducta migratoria. Varias especies abundantes se encuentran restringidas por la ZMO a la capa superior de 50 m. Sin embargo, otras especies abundantes habitan temporal o permanentemente la ZOM, contribuyendo sustancialmente al flujo vertical de C producido en la zona fótica a través de la migración vertical activa. La dinámica poblacional y las estrategias de los ciclos de vida, así como las adaptaciones metabólicas de las distintas especies, pueden no solo modular la contribución de ellas a los flujos verticales de C, sino que además a la mantención y persistencia de la masa de agua deficiente en oxígeno.

  16. Diel changes in phased-dividing cultures of Ceratium furca (dinophyceae): nucleotide triphosphates, adenylate energy charge, cell carbon, and patterns of vertical migration

    Energy Technology Data Exchange (ETDEWEB)

    Weiler, C.S.; Karl, D.M.

    1979-12-01

    The diel pattern of cell division, cell carbon, adenine nucleotides and vertical migration was determined for laboratory cultures of the photosynthetic marine dinoflagellate, Ceratium furca (Ehr.) Clap. and Lachm., entrained on an alternating 12:12 LD schedule at 20 C. Cell division was initiated during the latter portion of the dark period with ca. 30% of the population undergoing division. Cell C increased during the light period and exhibited a linear decrease with a loss of 33% during the dark period. ATP . cell/sup -1/ increased during the light period and decreased by Ca. 40 to 50% during the dark period. The diel patterns of cell C and ATP tended to buffer the magnitude of the change in C:ATP ratios around an overall mean value of 89. There was no obvious trend in the concentration of (GTP + UTP) . cell /sup -1/ over the cell cycle. The cellular adenylate energy charge was maintained at values between 0.8 to 0.9 throughout the 24 h LD cycle, despite a ca. 40% decrease in total adenylates (A/sub T/ = ATP + ADP + AMP) during the dark period on 12:12 LD, and over a 68% decrease in ATP during 42 h of continuous darkness. These data lend experimental support to the theory of cellular metabolic control by the adenine nucleotides. With lateral illumination on 12:12 LD cycles, the cells began to concentrate at the surface of the experimental tubes shortly before the lights were turned on, and at the bottom of the tubes shortly before the lights were extinguished. This patterncontinued for 6 days in continuous darkness, suggesting that the vertical migration pattern is independent of a phototactic response and may be under the control of an endogenous rhythm.

  17. Effects of phytoplankton vertical migration on the formation of oxygen depleted water in a shallow coastal sea

    Science.gov (United States)

    Haraguchi, K.; Yamamoto, T.; Chiba, S.; Shimizu, Y.; Nagao, M.

    2010-02-01

    In this paper, oxygen budget was estimated for the lower layer of water column in a semi-enclosed bay, Ago Bay, Japan. Benthic oxygen consumption rates were measured directly with an in situ measurement device from 13 July to 16 August 2004. Oxygen budget was calculated based on physical, chemical and biological processes using the observed data. Along with the change of the water column structure at the time of a hit of typhoon, dominant phytoplankton species shifted from the diatom Skeletonema costatum to the dinoflagellate Heterocapsa circularisquama. During the diatom-dominating period, oxygen supply rate in the lower layer due to photosynthesis was comparable to or slightly lower than the sediment oxygen consumption rate. In contrast, during the dominance of the dinoflagellate, net oxygen budget was significantly negative in the lower layer while it was positive in the upper layer. This could be attributed to the migration behavior of the dominant dinoflagellate H. circularisquama that swim up to the upper layer and produce oxygen in daytime, and swim down to the lower layer and consume oxygen in nighttime. The results of the present study suggest that phytoplankton migration behavior can enhance the development of oxygen depleted water mass in the lower layer of eutrophic shallow coastal seas.

  18. Influence of Irrigation Rate and Soil Type on the Vertical Migration of Iron and Manganese in the Soils of South-East Spain

    International Nuclear Information System (INIS)

    The citrus plantations in south-east Spain, situated largely on calcareous soils which are submitted to intensive cultivation, are investigating nutritional changes caused mainly by deficiencies of trace elements, especially iron and manganese, which result in a lower yield and premature exhaustion of the trees. The paper deals with a radioactive tracer study of the behaviour of these ions in soils and with the factors influencing their migration to the root zone; the object of the work is to develop a rational and economic fertilization policy. The work has been based on two types of soil, representing extreme situations encountered in practice; one soil is calcareous and the other non-calcareous. A set of columnsiwas assembled, each column having a length of 1 m and a cross-section of 32 cm2 ; solutions of 59Fe and 54Mn were added to these columns both in sulphate and chelate form. A definite amount of water, proportional to the requirements .of citrus plantations, was intermittently passed through these columns. Soil samples were taken periodically and the total activity and the activity of the assimilable and non-assimilable fractions of the elements being studied were measured. At the same time an apparatus involving a collimated scintillation detector was developed to follow the vertical migration of these ions in soils; the water drained from the columns after each irrigation was analysed radiochemically for the same purpose. (author)

  19. Zooplankton species identities, zooplankton species number per sample, and zooplankton abundance collected using zooplankton net as part of the California Cooperative Fisheries Investigation (CALCOFI) project, for 1994-03-01 (NODC Accession 9700104)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities, zooplankton species number per sample, and zooplankton abundance were collected from March 1, 1994 to March 1, 1994. Data were...

  20. Vertical nutrient and trace element migration in cambisoils after application of residues from anaerobic digestion of pig manure

    Science.gov (United States)

    Sager, Manfred; Unterfrauner, Hans

    2013-04-01

    Cambisols sampled in alpine pastures were packed into soil columns in order to monitor downward migration of nutrient and trace elements, applied within the residue from anaerobic digestion of a pig manure. 2 rain events per week were simulated. The manure added substantial amounts of K, ammonium, Na, Ca, P, S, Cl, B, Zn and Cu to the soil, whereas Mg, Mn, Ni, Cr, Pb, Cd and V were at the same level. In the eluates, total elemental composition as well as nitrate and ammonium were monitored. Addition of soluble Fe (at 1000 mg/l as FeCl3) decreased the release of soluble sulphate, but had no significant effect on the release of Fe and P. During subsequent rain events, exchangeable K remained enriched in the topsoil, wheras total sulfur moved to deeper layers. After 8 weeks, the columns were dismantled and analyzed for quasi-total and mobile fractions. Both in topsoils and subsoils, manure addition finally increased soil pH in case of low P soils, but decreased soil pH in case of high pH soils. Effects of manure applications on groundwater formation processes will be discussed.

  1. Zooplankton of the Zaporiz’ke Reservoir

    Directory of Open Access Journals (Sweden)

    T. V. Mykolaichuk

    2006-01-01

    Full Text Available The paper is devoted to zooplankton species composition in the Zaporiz’ke Reservoir. The greatest species diversity was found in the macrophyte communities of the upper reservoir’s littoral, but the least zooplankton diversity – in the pelagic zone of the lower reservoir.

  2. Near-surface enrichment of zooplankton over a shallow back reef: implications for coral reef food webs

    Science.gov (United States)

    Alldredge, A. L.; King, J. M.

    2009-12-01

    Zooplankton were 3-8 times more abundant during the day near the surface than elsewhere in the water column over a 1-2.4 m deep back reef in Moorea, French Polynesia. Zooplankton were also significantly more abundant near the surface at night although gradients were most pronounced under moonlight. Zooplankton in a unidirectional current became concentrated near the surface within 2 m of departing a well-mixed trough immediately behind the reef crest, indicating that upward swimming behavior, rather than near-bottom depletion by reef planktivores, was the proximal cause of these gradients. Zooplankton were highly enriched near the surface before and after a full lunar eclipse but distributed evenly throughout the water column during the eclipse itself supporting light as a proximal cue for the upward swimming behavior of many taxa. This is the first investigation of the vertical distribution of zooplankton over a shallow back reef typical of island barrier reef systems common around the world. Previous studies on deeper fringing reefs found zooplankton depletion near the bottom but no enrichment aloft. In Moorea, where seawater is continuously recirculated out the lagoon and back across the reef crest onto the back reef, selection for upward swimming behavior may be especially strong, because the surface serves both as a refuge from predation and an optimum location for retention within the reef system. Planktivorous fish and corals that can forage or grow even marginally higher in the water column might have a substantial competitive advantage over those nearer the bottom on shallow reefs. Zooplankton abundance varied more over a few tens of centimeters vertical distance than it did between seasons or even between day and night indicating that great care must be taken to accurately assess the availability of zooplankton as food on shallow reefs.

  3. Eclipse effects on field crops and marine zooplankton: the 29 March 2006 Total Solar Eclipse

    Directory of Open Access Journals (Sweden)

    G. Economou

    2008-01-01

    Full Text Available The effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on the photoenergetic and photoregulatory plant processes, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 ?mol CO2 m?2 s?1. However, since solar irradiance attenuation has not at the same time induced stomatal closure thus not blocking CO2 uptake by plants, it is probably other endogenous factors that has been responsible for the observed fall in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates, and meso-zooplankton due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

  4. Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

    Directory of Open Access Journals (Sweden)

    G. Economou

    2008-08-01

    Full Text Available Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 ?mol CO2 m?2 s?1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates, and meso-zooplankton due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

  5. Three-dimensional acoustic visualization of zooplankton patchiness

    Science.gov (United States)

    Greene, Charles H.; Wiebe, Peter H.; Pelkie, Chris; Benfield, Mark C.; Popp, Jacqueline M.

    Acoustic data were collected and visualized to characterize the 3-dimensional patchiness of zooplankton at a thermally stratified site on Georges Bank. The work was carried out as part of a field study conducted to examine the effects of springtime water-column stratification on the distributions of zooplankton and larval fish on the Bank. The acoustic data were acquired as the ship steamed a survey grid relative to the track of a surface drifter with a subsurface drogue. Although quite irregular in geographical coordinate space, the ship's track relative to the moving water closely matched the intended grid pattern once the drifter's movement in the tidal flow was taken into account. After changing coordinate systems to compensate for tidal advection, the acoustic data set was transformed from its curtain-like distribution in 3-dimensional space to a volumetric distribution. Two-dimensional point kriging was performed on the irregularly spaced data from each 2-m-thick depth stratum to produce a series of 2-dimensional, regularly spaced data grids. These data grids were then stacked to construct the 3-dimensional data grid required for volumetric visualization. A similar procedure was followed with the error variance values produced at each grid point through kriging to construct a 3-dimensional, volumetric distribution of the error variance. To examine zooplankton patchiness within the surveyed volume of water, isosurfaces corresponding to specific levels of acoustic backscatter were highlighted in the visualization. The 3-dimensional distribution of error variance was used to control the opacity of the isosurfaces to provide an objective, visual approach for displaying the statistical confidence one can have in the patches detected. In this survey, the ship steamed directly over a large, southwest- to northeast-oriented patch of zooplankton on at least three different passes. It also steamed over several smaller patches. The vertically compressed nature of the patches and their high degree of spatial heterogeneity in the horizontal plane are characteristic of the zooplankton distributions found in the deeper, seasonally stratified portions of Georges Bank.

  6. Estructura comunitaria del zooplancton asociada con el fitoplancton y las masas de agua del Estrecho de Bransfield y la Isla Elefante durante el verano austral del 2006 / Zooplankton community structure and its association with the phytoplankton and water masses from the Bransfield strait and elephant island during 2006 austral summer

    Scientific Electronic Library Online (English)

    Jessica, Bonicelli P.; Diana, López P.; Noemí, Ochoa L.; Rachael S., Shreeve.

    2008-12-01

    Full Text Available Durante el verano austral del año 2006, la abundancia y distribución espacial del zooplancton y su asociación con algunas variables físicas (masas de agua) y biológicas (fitoplancton) fueron investigadas en el Estrecho de Bransfield y al sureste de la Isla Elefante. La comunidad estuvo compuesta pri [...] ncipalmente por copépodos, siendo las especies más abundantes Metridia gerlachei y Ctenocalanus sp. Mediante el análisis cluster se diferenciaron 3 grupos de estaciones asociados con las masas de agua. Un grupo se halló al sureste de la Isla Elefante y del Estrecho de Bransfield, donde predominó la masa de agua del mar de Weddell. Allí el fitoplancton fue escaso, mientras que el zooplancton fue abundante. Esto puede ser un ejemplo de un control top-down debido al pastoreo. Otro grupo se distribuyó al noroeste del Estrecho, donde predominaron las aguas del mar de Bellingshausen, en esta zona el zooplancton tuvo abundancias bajas, mientras que el fitoplancton fue encontrado en altas concentraciones. El último grupo fue encontrado en el centro del estrecho, en donde se encuentra el Frente de Bransfield. A pesar de las altas abundancias de fitoplancton, la mayoría de especies zooplanctónicas presentaron bajas abundancias, pudiendo ser por las fuertes turbulencias que se forman en el Frente. Sin embargo, Metridia gerlachei fue la más abundante en esta zona probablemente por su extensa migración vertical. Abstract in english During the austral summer of 2006 the spatial distribution of zooplankton and its association with some abiotic (water masses) and biotic variables (phytoplankton) were investigated in the Bransfield Strait and to the southeast of Elephant Island, Southern Ocean. The zooplankton community was mainly [...] composed of copepods; the main species present were Metridia gerlachei and Ctenocalanus sp. Nearest neighbor cluster analysis of zooplankton indicated the presence of three major station groupings which were influenced by water masses. One group was found in the southeast of the Bransfield Strait and Elephant Island, where the Weddell water masses predominated. This showed low phytoplankton abundance, whilst zooplankton abundance was high. This may be an example of top down grazing control. A second group was found in the northwest of the Strait, where the Bellingshausen water masses predominated. Here the zooplankton abundance was low, whilst the phytoplankton was found in high concentrations. A third group was found in the Bransfield front. Despite the high abundances of phytoplankton located here, zooplankton abundance was low. This could be due to the strong turbulence at the front. However, Metridia gerlachei was found in much higher concentrations here than other copepods. This species may be able to cope with such conditions due to its extensive diurnal vertical migrations.

  7. Trait-based approaches to zooplankton communities

    DEFF Research Database (Denmark)

    Lichtman, E.; Ohman, M.D.

    2013-01-01

    Zooplankton are major primary consumers and predators in most aquatic ecosystems. They exhibit tremendous diversity of traits, ecological strategies and, consequently, impacts on other trophic levels and the cycling of materials and energy. An adequate representation of this diversity in community and ecosystem models is necessary to generate realistic predictions on the functioning of aquatic ecosystems but remains extremely challenging. We propose that the use of trait-based approaches is a promising way to reduce complexity while retaining realism in developing novel descriptions of zooplankton in ecosystem models. Characterizing zooplankton traits and trade-offs will also be helpful in understanding the selection pressures and diversity patterns that emerge in different ecosystems along major environmental gradients. Zooplankton traits can be characterized according to their function and type. Some traits, such as body size and motility, transcend several functions and are major determinants of zooplankton ecological strategies. Future developments of trait-based approaches to zooplankton should assemble a comprehensive matrix of key traits for diverse groups and explore it for general patterns; develop novel predictive models that explicitly incorporate traits and associated trade-offs; and utilize these traits to explain and predict zooplankton community structure and dynamics under different environmental conditions, including global change scenarios

  8. Fish-mediated trait compensation in zooplankton

    DEFF Research Database (Denmark)

    Hylander, Samuel; Souza, M.S.

    2012-01-01

    1. Environmental factors fluctuate spatially and temporally, and organisms that can alter phenotype in response to these changes may increase their fitness. Zooplankton are known to be able to induce body pigmentation in response to ultraviolet radiation (UVR) and to reduce the pigmentation when exposed to fish predators. Hence, reduced pigmentation because of the presence of fish could potentially lead to UVR damage, which calls for alternative protective echanisms. 2. We exposed zooplankton to fish cues and UVR stress to assess whether body pigmentation and cellular antioxidants are flexible predation and UVR defences. 3. Zooplankton exposed to fish predator cues (no direct predation) reduced their pigmentation by c. 30% in 20 days. However, they were able to rapidly counteract negative UVR effects by increasing the activity of antioxidant defences such as glutathione S-transferase (GST). When exposed to UVR, the GST activity increased by c. 100% in zooplankton that had previously reduced their pigmentation because of fish cues. Transparency in the zooplankton did not lead to considerably higher UVR damage, here measured as inhibition of olinesterase (ChE). 4. We conclude that zooplankton pigmentation and antioxidant enzymes are flexible UVR defence systems, which can be induced when needed. Zooplankton may employ antioxidant defences when pigmentation is reduced to counteract predation risk and thereby rapidly respond to detrimental effects of UVR exposure, that is, they can compensate one trait with another

  9. Zooplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Jyothibabu, R.; Madhu, N.V.

    ://www.ngdc.noaa.gov/mgg/topo/globe.html. Godhantaraman N. (1994) Species composition and abundance of tintinnids and copepods in the Pichavaram mangroves (South India); Ciencias Marinas 20 371?391. Goswami S. C. (1983) Coexistence and succession of copepod species in the Mandovi and Zuari estuaries...

  10. A Review: Potentiality of Zooplankton as Bioindicator

    OpenAIRE

    Zannatul Ferdous; A. K.M Muktadir

    2009-01-01

    Problem statement: This review tended to summarize some recent research on zooplankton as bioindicator in India and some other countries of the world. Approach: These researches were mainly on fresh water bodies. Results: Qualitative as well as quantitative analysis were done by Shannon diversity index (H'), Evenness index (J), Species Richness index (S) and Saprobic index. In most of the cases zooplankton population size was correlated with biotic and abiotic parameters (pH, alkalinity, temp...

  11. Distribución espacial de larvas de crustáceos decápodos planctónicos en canales orientales de la isla Chiloé, Chile / Vertical distribution of planktonic decapods crustacean larvae in oriental channels of the Chiloé Island, Chile

    Scientific Electronic Library Online (English)

    Armando, Mujica; María L, Nava.

    Full Text Available Se analiza la distribución vertical y abundancia de larvas de crustáceos decápodos planctónicos en canales orientales de la isla Chiloé. Se relaciona la distribución de larvas con la hora de captura y marea, que interferirían con las migraciones verticales u ontogénicas descritas para el meroplancto [...] n. De las especies identificadas, las larvas de Neotrypaea uncinata fueron las más abundantes. Su distribución vertical, fue inversa a la descrita para la migración circadiaria de zooplancton, sin que se encontraran diferencias significativas en la abundancia en los dos estratos de profundidad. Las abundancias de larvas de Cancridae y Pinnotheridae, fueron las únicas que tuvieron diferencias significativas en ambos estratos, aunque inversas al patrón de distribución vertical circadiaria. La amplitud de marea y dinámica oceanográfica descrita para los canales del área de estudio, serían determinantes en la distribución de las larvas en el sector, sobreponiéndose el transporte de ellas al comportamiento migratorio descrito para el zooplancton en general. Abstract in english The vertical distribution and abundance of planktonic decapods larvae in channels from the inside part of Chiloé Island is analyzed. The larvae distribution is related with the capture daytime and the tide conditions and which could interfere with the vertical or ontogenic migrations described for t [...] he meroplankton. From the identified species, the Neotrypaea uncinata larvae were the most abundant. Their vertical distribution was inverse to the one described by the circadian migration of the zooplankton, without detecting significant differences among the abundances in both sampled strata. The abundance of Cancridae and Pinnotheridae larvae were the only ones that had significant differences in the two strata, although they were inverse to the pattern of circadian vertical distribution. The tide height and the oceanographic dynamic described for the channels of the area under study would be decisive in the distribution of larvae in the sector, overcoming their transport to the migratory behavior described for the zooplankton in general.

  12. Emergent and floating-leaved macrophytes as refuge for zooplankton in a eutrophic temperate lake without submerged vegetation

    DEFF Research Database (Denmark)

    Cazzanelli, Matteo; Perlt, Trine Warming

    2008-01-01

    Several studies have shown that submerged macrophytes provide a refuge for zooplankton against fish predation, whereas the role of emergent and floating-leaved species, which are often dominant in eutrophic turbid lakes, is far less investigated. Zooplankton density in open water and amongst emergent and floating-leaved vegetation was monitored in a small, eutrophic lake (Frederiksborg Slotssø) in Denmark during July-October 2006. Emergent and floating-leaved macrophytes harboured significantly higher densities of pelagic as well as plant-associated zooplankton species, compared to the open water, even during periods where the predation pressure was presumably high (during the recruitment of 0+ fish fry). Zooplankton abundance in open water and among vegetation exhibited low values in July and peaked in August. Bosmina and Ceriodaphnia dominated the zooplankton community in the littoral vegetated areas (up to 4,400 ind l-1 among Phragmites australis and 11,000 ind l-1 between Polygonum amphibium stands), whereas the dominant species in the pelagic were Daphnia (up to 67 ind l-1) and Cyclops (41 ind l-1). The zooplankton density pattern observed was probably a consequence of concomitant modifications in the predation pressure, refuge availability and concentration of cyanobacteria in the lake. It is suggested that emergent and floating-leaved macrophytes may play an important role in enhancing water clarity due to increased grazing pressure by zooplankton migrating into the plant stands. As a consequence, especially in turbid lakes, the ecological role of these functional types of vegetation, and not merely that of submerged macrophyte species, should be taken into consideration.

  13. Zooplankton characteristics of the coastal ecosystem off Bombay, India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Ramaiah, Neelam

    The nearshore waters of Bombay sustain a rich and diverse zooplankton fauna. Continuous observations for a period of 15 months indicated a variation from 0.4 to 19.9 mg C.m sup(3) (av. 4.3 mg C.m sup(-3)) in zooplankton biomass. The zooplankton...

  14. A Review: Potentiality of Zooplankton as Bioindicator

    Directory of Open Access Journals (Sweden)

    Zannatul Ferdous

    2009-01-01

    Full Text Available Problem statement: This review tended to summarize some recent research on zooplankton as bioindicator in India and some other countries of the world. Approach: These researches were mainly on fresh water bodies. Results: Qualitative as well as quantitative analysis were done by Shannon diversity index (H', Evenness index (J, Species Richness index (S and Saprobic index. In most of the cases zooplankton population size was correlated with biotic and abiotic parameters (pH, alkalinity, temperature, dissolve oxygen, transparency, phosphate, chlorine. Species of Rotifers, Cladocerans, Copepods and Ostracods were found in all cases. Species variation of these order deceased in polluted water. Some species were not found in some highly polluted area though these species have high tolerance level. Conclusion/Recommendations: All the results of the studies indicated that potentiality of zooplankton as bioindicator is very high. Other countries can develop these concepts to monitor water quality.

  15. ZOOPLANKTON OCCURANCE DURING MONSOON SEASON FROM EKRUK TANK, SOLAPUR

    Directory of Open Access Journals (Sweden)

    M. R. Gurav , K. R. Rao

    2014-06-01

    Full Text Available In the present study zooplankton occurrence and abundance were investigated from Ekruk tank, Solapur. Samples were collected bimonthly for a duration of four months in monsoon season (July to October 2012. The results showed that the occurrence of zooplanktons such as Rotifers, Copepods and Cladocerans during the investigation. Physico- chemical parameters of given water plays an important role in occurrence and abundance of zooplankton species. These environmental factors mainly affect the distribution of zooplankton species from Ekruk tank, Solapur. Our results are discussed in the light of the seasonal effect on the occurrence of zooplankton community.

  16. Effect of Water Hyacinth (Eichornia crassippes Infestation on Zooplankton Populations in Awba Reservoir, Ibadan South-West Nigeria

    Directory of Open Access Journals (Sweden)

    K.S. Chukwuka

    2007-01-01

    Full Text Available The effects of water hyacinth infestation on the distribution, abundance and species composition of zooplankton in Awba reservoir were investigated. Samples were collected in each of the sampling areas (water hyacinth infested and open water by vertical zooplankton hauls using 64 um bolting silk net. The samples were immediately fixed in 4% formalin for preservation. The species composition of the zooplankton from the sampled areas consisted of 3 taxa, comprising of 6 species of Cladocera (Moina sp., Ceriodaphnia sp., Pleuroxus sp., Diaphanosoma sp., Chydorus sp. and Leydigia sp. 6 species of Rotifers (Asplanchna sp., Trichocerca, Filinia sp., Polyarthra sp., Brachionus sp. and Lecane sp. and 3 species of Copepoda (Cycloid copepods, Copepodite nauphii and Calanoid copepods. However, the study showed that the Rotifers had higher numerical abundance in the study areas. Water hyacinth infested area had a total density of 95 individuals/L while open water had 215 individuals/L. The study showed that the density of zooplanktons were significantly lower (p< 0.05 in the infested area. Biotic indices such as Margalef`s and Simpson`s indices were lower in the infested area while Shannon-wiener diversity index was significantly lower (p< 0.05 in the water hyacinth infested area. The result suggests that water hyacinth dense mats affected the numerical abundance of the zooplanktons.

  17. Rapid removal of plutonium from the oceanic surface layer by zooplankton faecal pellets

    International Nuclear Information System (INIS)

    In view of the possibility that increasing quantities of Pu may in due course be introduced into the marine environment, it is important to have a detailed knowledge of its oceanic behaviour. It has been suggested that algae and perhaps the phytoplanktonic mass may have an important role in determining the chemical and physical forms of Pu predominant in the ocean. The role of the zooplanktonic mass has not been investigated in detail, but it is known that for several elements zooplankton metabolism may be an important biological factor in the removal of elements from the surface layers of the ocean. The particular importance of zooplankton faecal pellets in this process has been stressed, and it has been found that M. norvegica is rich in the naturally-occurring ?-emitter 210Po when compared with whole organism levels. A study is here described for Pu, and it is reported that M. norvegica faecal pellets are relatively rich in Pu. It is suggested that zooplankton faecal pellet deposition might be an important vector in the vertical oceanic transport of this element. Experimental details are given and results are shown in tabular form. The implications of the high concentrations of Pu in faecal pellets are described, and rough estimates are made for the removal time of Pu from the upper mixed ocean layers by zooplankton pellets alone; the result is 3.6 years. It is suggested that faecal pellets may have a significant role in the removal of Pu from the surface layers of the sea. (U.K.)

  18. Zooplankton may serve as transmission vectors for viruses infecting algal blooms in the ocean.

    Science.gov (United States)

    Frada, Miguel José; Schatz, Daniella; Farstey, Viviana; Ossolinski, Justin E; Sabanay, Helena; Ben-Dor, Shifra; Koren, Ilan; Vardi, Assaf

    2014-11-01

    Marine viruses are recognized as a major driving force regulating phytoplankton community composition and nutrient cycling in the oceans. Yet, little is known about mechanisms that influence viral dispersal in aquatic systems, other than physical processes, and that lead to the rapid demise of large-scale algal blooms in the oceans. Here, we show that copepods, abundant migrating crustaceans that graze on phytoplankton, as well as other zooplankton can accumulate and mediate the transmission of viruses infecting Emiliania huxleyi, a bloom-forming coccolithophore that plays an important role in the carbon cycle. We detected by PCR that >80% of copepods collected during a North Atlantic E. huxleyi bloom carried E. huxleyi virus (EhV) DNA. We demonstrated by isolating a new infectious EhV strain from a copepod microbiome that these viruses are infectious. We further showed that EhVs can accumulate in high titers within zooplankton guts during feeding or can be adsorbed to their surface. Subsequently, EhV can be dispersed by detachment or via viral-dense fecal pellets over a period of 1 day postfeeding on EhV-infected algal cells, readily infecting new host populations. Intriguingly, the passage through zooplankton guts prolonged EhV's half-life of infectivity by 35%, relative to free virions in seawater, potentially enhancing viral transmission. We propose that zooplankton, swimming through topographically adjacent phytoplankton micropatches and migrating daily over large areas across physically separated water masses, can serve as viral vectors, boosting host-virus contact rates and potentially accelerating the demise of large-scale phytoplankton blooms. PMID:25438947

  19. Swimming in turbulence: zooplankton fitness in terms of foraging efficiency and predation risk

    DEFF Research Database (Denmark)

    Visser, Andre; Mariani, Patrizio

    2009-01-01

    Turbulence impacts zooplankton fitness in opposing manners, by increasing contacts with prey but at the same time increasing contacts with predators. We investigate the fitness of individual zooplankton in terms of a trade-off between energetic gains and costs, and risk of predation. Through idealized descriptions of foraging and predation in a turbulent water column, we determine how fast a zooplankter should swim, if at all, and where should it position itself in the vertical to maximize its fitness given certain environmental conditions. Suspension feeding has an advantage over ambush feeding at high turbulence levels, whereas cruise feeding becomes optimal at low turbulence levels. In general, behaviours that seek out low levels of turbulence increase an individual's fitness, a prediction that runs counter to turbulent encounter rate arguments, and exposes the fallacy of examining only the foraging aspects of the fitness trade-off.

  20. Vertical migration of {sup 60}Co, {sup 137}Cs and {sup 226}Ra in agricultural soils as observed in lysimeters under crop rotation

    Energy Technology Data Exchange (ETDEWEB)

    Shinonaga, T. [Division of Environmental and Life Science, ARC Seibersdorf Research, A-2444 Seibersdorf (Austria)]. E-mail: t.shinonaga@iaea.org; Schimmack, W. [Institute of Radiation Protection, GSF-National Research Center for Environment and Health, D-85764 Neuherberg (Germany); Gerzabek, M.H. [Division of Environmental and Life Science, ARC Seibersdorf Research, A-2444 Seibersdorf (Austria); Department for Forest and Soil Sciences, University of Natural Resources and Applied Life Science, Gregor-Mendel-Strasse 33, A-1180 Vienna (Austria)

    2005-07-01

    In most studies quantifying the migration parameters - apparent migration velocity and apparent dispersion coefficient - of radionuclides in the soil by model calculations, these parameters are determined for undisturbed soils. For soils disturbed by ploughing, however, no such data are available in the literature. Therefore, in the present study, the migration parameters of {sup 137}Cs, {sup 60}Co and {sup 226}Ra were estimated for ploughed soils by means of a convection-dispersion model. The depth distributions of the radionuclides were determined in four lysimeters (area: 1 m{sup 2}, depth of soil monolith: 0.75 m) filled with artificially contaminated soils of different types in July 1990. The lysimeters were cropped with agricultural plants. The soil in each lysimeter was ploughed manually once a year until 1996 (plough depth 20 cm). In July 1999, soil samples were collected from three pits in each lysimeter. The depth distributions of all radionuclides proved to be very similar in each soil pit. The spatial variability of the depth distributions of a given radionuclide within the lysimeters was about the same as their variability between the four lysimeters. Evaluation of the migration parameters revealed that the convective transport of the radionuclides was always rather small or even zero, while the dispersive transport caused a 'melting' process of the initially sharp activity edge at the lower border of the Ap horizon. These results are explained by the high evapotranspiration (80-90% of the total precipitation plus irrigation) and the small amounts of seepage water during the observation period of 9 years.

  1. Survival probability of larval sprat in response to decadal changes in diel vertical migration behavior and prey abundance in the Baltic Sea

    DEFF Research Database (Denmark)

    Hinrichsen, Hans-Harald; Peck, Myron A.; Schmidt, Jörn; Huwer, Bastian; Voss, Rudi

    2010-01-01

    We employed a coupled three-dimensional biophysical model to explore long-term inter- and intra-annual variability in the survival of sprat larvae in the Bornholm Basin, a major sprat spawning area in the Baltic Sea. Model scenarios incorporated observed decadal changes in larval diel vertical distribution and climate-driven abiotic and biotic environmental factors including variability in the abundance of different, key prey species (calanoid copepods) as well as seasonal changes, long-term tre...

  2. Experiments on the influence of Chaoborus brasiliensis Theobald, 1901 (Diptera: Chaoboridae) on the diel vertical migration of microcrustaceans from Lake Monte Alegre, Brazil / Experimentos sobre a influência de Chaoborus brasiliensis (Diptera: Chaoboridae) sobre a migração vertical de microcrustáceos do Lago Monte Alegre, Brasil

    Scientific Electronic Library Online (English)

    WJ., Minto; MS., Arcifa; A., Perticarrari.

    2010-02-01

    Full Text Available O objetivo deste trabalho foi avaliar se a migração vertical dos microcrustáceos do Lago Monte Alegre é relacionada aos predadores invertebrados, nomeadamente larvas de Chaoborus brasiliensis. A hipótese testada no experimento foi a de que o comportamento migratório da presa seria dependente do cont [...] ato físico com as larvas de Chaoborus ou dos "kairomones" liberados por elas. Dois experimentos foram realizados no laboratório, com dois tratamentos e três réplicas cada. Os experimentos foram feitos dentro de cilindros de acrílico de 1,5 m de altura e 0,20 m de diâmetro. Os tratamentos do Experimento I foram: A) predador e "kairomones" presentes e B) predador e "kairomones" presentes, mas o predador isolado em tubos de rede dentro do cilindro, não tendo contato físico com a presa. Os tratamentos do Experimento II foram: A) predador e "kairomones" ausentes e B) igual ao Experimento I. Fatores físicos e químicos (temperatura, oxigênio dissolvido, pH, condutividade elétrica) e alimento (algas) não influenciaram a distribuição vertical das presas, pois eles estavam quase homogeneamente distribuídos na coluna d'água em ambos os experimentos; as concentrações de alimento não foram limitantes. Copépodos adultos (Tropocyclops prasinus meridionalis e Thermocyclops decipiens) realizaram migração reversa no tratamento B dos dois experimentos; o cladócero Daphnia gessneri migrou de modo noturno no tratamento A do Experimento I; migração vertical não foi detectada para copepoditos, bem como para larvas de Chaoborus. Os experimentos indicaram que Daphnia respondeu ao contato físico com as larvas de Chaoborus e não aos "kairomones". Copépodos adultos foram aparentemente mais sensíveis aos "kairomones". Abstract in english The aim of this work was to evaluate whether diel vertical migration of microcrustaceans from Lake Monte Alegre is related to invertebrate predators, namely larvae of Chaoborus brasiliensis. The hypothesis tested in the experiments was that the migratory behaviour of prey would depend on physical co [...] ntact with Chaoborus brasiliensis larvae or with kairomones released by them. Two experiments were undertaken in the laboratory, with two treatments and three replicates each. Experiments were carried out in acrylic cylinders 1.5 m high and 0.20 m in diameter. Treatments in Experiment I were: A) predator and kairomones present and B) predator and kairomones present, but predator isolated in net tube inside the cylinder, having no physical contact with prey. Treatments in Experiment II were: A) predator and kairomones absent and B) the same as in experiment I. Physical and chemical factors (temperature, dissolved oxygen, pH, electrical conductivity) and food (algae) did not influence vertical distribution of prey, as they were almost homogeneously distributed in the water column in both experiments; food concentrations were not limiting. Adult copepods (Tropocyclops prasinus meridionalis and Thermocyclops decipiens) showed reverse migration in the treatment B of both experiments; the cladoceran Daphnia gessneri migrated nocturnally in the treatment A of the Experiment I; vertical migration was undetectable for copepodites, as well as for Chaoborus larvae. The experiments indicated that Daphnia responded to physical contact with Chaoborus larvae but not to kairomones alone. Adult copepods seemed to be more sensitive to kairomones.

  3. Zooplankton, especially calanoid copepods, in the upper 1000m of the south-east Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Haridas, P.

    and adults of subtropical oceanic copepods. Mar. BioI., 94, 561-577. Angel,M. V. (1979) Studies on Atlantic halocyprid ostracods: their vertical distributions and community structure in the central gyre region along latitude 30"N from Africa to Bermuda. Prog..., especially euphausiids in the eastern tropical Pacific. Prog. Oceanogr., 8, 125-189. Deevey,G.B. and Brooks,A.L. (1971) The annual cycle in quantity and composition ofth.~ zooplankton of the Sargasso Sea off Bermuda. 11. The surface to 2000 m. Limnol...

  4. Seasonal Variations of the Zooplankton Composition and Abundance in the Istanbul Strait

    Directory of Open Access Journals (Sweden)

    Ahmet Nuri Tarkan

    2005-01-01

    Full Text Available Composition and variation of zooplankton of the Istanbul Strait were studied to obtain information on the distribution, abundance and biomass of dominant zooplankton species in the both layers of Black Sea and Mediterranean Sea of Istanbul Strait and to determine the exchange of these species between those layers. Samples were collected vertically, using WP2 nets. In winter sampling period, the copepod Acartia clausi took part in the first place in abundance and meroplankton of bivalves occupied the second place. In the samples collected during spring period, diversity and abundance of different species were higher than other seasonal periods. Noctiluca scintillans with an abundance value of 2380 ind./m-3 was the dominant species, which was followed by A. clausi with 2156 ind./m-3 in the samples collected from the upper layer, while A. clausi showed the highest abundance with 924 ind./m-3, followed by the meroplankton of bivalves with 840 ind./m-3 in the samples collected from the lower layer. In summer period, A. clausi with 952 ind./m-3 and Penilia avirostris with 840 ind./m3 were collected intensively. In the Black Sea water average zooplankton abundance in winter period were 3485 ind./m-3 and during this time A. clausi was found to be the dominant species (976 ind./m-3. A second increase in the population of zooplankton was observed in the autumn period with a total abundance of 5969 ind./m-3. This study carried out seasonally through the year was important in determining dominant species of Istanbul Strait, towards understanding the ecology of the region.

  5. Zooplankton composition in Dharamtar creek adjoining Bombay harbour

    Digital Repository Service at National Institute of Oceanography (India)

    Tiwari, L.R; Nair, V.R

    Dharamtar creek (Bombay, India) creek maintained rich zooplankton standing stock (av. 30.3 ml 100 m/3) with peak production during August-November. Zooplankton production rate for the entire system amounted to 10.32 mg C.100 m/3 d/1 with an annual...

  6. Biochemical composition of Antarctic zooplankton from the Indian Ocean sector

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Parulekar, A.H.

    Zooplankton samples were analysed for faunal composition, organic carbon, protein, carbohydrate and lipid content. Total zooplankton biomass (as displacement volume) varied from 0.032 to 0.500 ml.m sup(-3) (x = 0.23 + or - 0.14) in upper 200 m...

  7. Zooplankton assemblage of Oyun Reservoir, Offa, Nigeria

    Scientific Electronic Library Online (English)

    Moshood K, Mustapha.

    2009-12-01

    Full Text Available La influencia de las propiedades fisicoquímicas del Reservorio Oyun, Offa, Nigeria (un embalse tropical somero) sobre la composición y abundancia del zooplancton fue investigada en tres estaciones entre enero de 2002 y diciembre de 2003. La diversidad no resultó muy alta con tres grupos de zooplanct [...] on: Rotifera con ocho géneros, y Cladocera y Copepoda con tres géneros cada uno. Rotifera dominó (71.02%), seguido de Cladocera (16.45%) y Copepoda (12.53%). El zooplancton fue más común durante la temporada de lluvias, y hubo variaciones en su composición y abundancia a lo largo del embalse. Factores tales como la temperatura, los nutrientes, la disponibilidad de alimentos, la forma y la hidrodinámica del embalse, así como las estrategias reproductivas de los organismos, influyen fuertemente en la composición genérica y la densidad poblacional del zooplancton. La prevención del deterioro ecológico de esta masa de agua, resultaría en un cuerpo de agua más productivo, rico en zooplancton y con mejor pesca. Abstract in english The influence of physico-chemical properties of Oyun Reservoir, Offa, Nigeria (a shallow tropical African reservoir) on its zooplankton composition and abundance were investigated at three stations for two years between January 2002 and December 2003. Diversity is not high: only three groups of zoop [...] lankton were found: Rotifera with eight genera; and Cladocera and Copepoda with three genera each. Rotifera dominated numerically (71.02%), followed by Cladocera (16.45%) and Copepoda (12.53%). The zooplankton was more prevalent during the rainy season, and there were variations in the composition and abundance along the reservoir continuum. Factors such as temperature, nutrients, food availability, shape and hydrodynamics of the reservoir, as well as reproductive strategies of the organisms, strongly influence the generic composition and population density of zooplankton. Prevention of ecological deterioration of the water body would greatly should result in a more productive water body, rich in zooplankton and with better fisheries. Rev. Biol. Trop. 57 (4): 1027-1047. Epub 2009 December 01.

  8. Short term changes in zooplankton community during the summer-autumn transition in the open NW Mediterranean Sea: species composition, abundance and diversity

    Directory of Open Access Journals (Sweden)

    V. Raybaud

    2008-05-01

    Full Text Available Short term changes in zooplankton community were investigated at a fixed station in offshore waters of the Ligurian Sea (Dynaproc 2 cruise, September–October 2004. Mesozooplankton was sampled with vertical WP2 hauls (200 µm mesh-size and large mesozooplankton, macrozooplankton and micronekton with a BIONESS multinet sampler (500 µm mesh-size. Temporal variations of total biomass, species composition and abundance of major taxa were studied. Intrusions of low salinity water masses were observed two times during the cruise. The first one, which was the most important, was associated with changes in zooplankton community composition. Among copepods, the abundance of Calocalanus, Euchaeta, Heterorhabdus, Mesocalanus, Nannocalanus, Neocalanus, Pleuromamma and also calanoid copepodites increased markedly. Among non-copepod taxa, only small ostracods abundance increased. After this low salinity event, abundance of all taxa nearly returned to their initial values. The influence of salinity on each zooplankton taxon was confirmed by a statistical analysis (Perry's method. Shannon diversity index, Pielou evenness and species richness were used to describe temporal variations of large copepod (>500 µm diversity. Shannon index and Pielou evenness decreased at the beginning of the low salinity water intrusions, but not species richness. We suggest that low salinity water masses contained its own zooplankton community and passed through the sampling area, thus causing the replacement of zooplankton population.

  9. Hydrostatic Pressure and Temperature Effects on the Membranes of a Seasonally Migrating Marine Copepod

    Science.gov (United States)

    Pond, David W.; Tarling, Geraint A.; Mayor, Daniel J.

    2014-01-01

    Marine planktonic copepods of the order Calanoida are central to the ecology and productivity of high latitude ecosystems, representing the interface between primary producers and fish. These animals typically undertake a seasonal vertical migration into the deep sea, where they remain dormant for periods of between three and nine months. Descending copepods are subject to low temperatures and increased hydrostatic pressures. Nothing is known about how these organisms adapt their membranes to these environmental stressors. We collected copepods (Calanoides acutus) from the Southern Ocean at depth horizons ranging from surface waters down to 1000 m. Temperature and/or pressure both had significant, additive effects on the overall composition of the membrane phospholipid fatty acids (PLFAs) in C. acutus. The most prominent constituent of the PLFAs, the polyunsaturated fatty acid docosahexanoic acid [DHA – 22:6(n-3)], was affected by a significant interaction between temperature and pressure. This moiety increased with pressure, with the rate of increase being greater at colder temperatures. We suggest that DHA is key to the physiological adaptations of vertically migrating zooplankton, most likely because the biophysical properties of this compound are suited to maintaining membrane order in the cold, high pressure conditions that persist in the deep sea. As copepods cannot synthesise DHA and do not feed during dormancy, sufficient DHA must be accumulated through ingestion before migration is initiated. Climate-driven changes in the timing and abundance of the flagellated microplankton that supply DHA to copepods have major implications for the capacity of these animals to undertake their seasonal life cycle successfully. PMID:25338196

  10. Zooplankton species identities and other data collected from zooplankton net casts in the NE Atlantic Ocean from DISCOVERY; 12 November 1969 to 01 July 1988 (NODC Accession 9500097)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities and other data were collected by DISCOVERY using zooplankton net casts in the Northeast Atlantic Ocean. Data were collected from 12...

  11. Zooplankton distribution in the polluted environment around Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Abidi, S.A.H.

    Zooplankton distribution, abundance and composition with reference to polluted environments off Bombay was estimated. This study was taken up along three transects viz. Versova, Mahim and Thana covering eleven stations around Bombay during 1980...

  12. Rapid local adaptation mediates zooplankton community assembly in experimental mesocosms.

    Science.gov (United States)

    Pantel, Jelena H; Duvivier, Cathy; Meester, Luc De

    2015-10-01

    Adaptive evolution can occur over similar timescales as ecological processes such as community assembly, but its particular effects on community assembly and structure and their magnitude are poorly understood. In experimental evolution trials, Daphnia magna were exposed to varying environments (presence and absence of fish and artificial macrophytes) for 2 months. Then, in a common gardening experiment, we compared zooplankton community composition when either experimentally adapted or D. magna from the original population were present. Local adaptation of D. magna significantly altered zooplankton community composition, leading to a suppression of abundances for some zooplankton taxa and facilitation for others. The effect size of D. magna adaptation was similar to that of adding fish or macrophytes to mesocosms, two important drivers of zooplankton community structure. Our results suggest that substantial amounts of variation in community composition in natural systems may be unexplained if evolutionary dynamics are ignored. PMID:26251339

  13. Stratification of zooplankton in the northwestern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Paulinose, V.T.; Gopalakrishnan, T.C.; Nair, K.K.C.; Aravindakshan, P.N.

    Study on stratification of zooplankton in the north western Indian Ocean was carried out with special reference to its relative abundance and distribution. Samples were collected using multiple plankton net, during first cruise of ORV Sagar Kanya...

  14. Flow disturbances generated by feeding and swimming zooplankton

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, Haisong; Goncalves, R. J.; Nielsen, L. T.; Wadhwa, Navish

    2014-01-01

    Interactions between planktonic organisms, such as detection of prey, predators, and mates, are often mediated by fluid signals. Consequently, many plankton predators perceive their prey from the fluid disturbances that it generates when it feeds and swims. Zooplankton should therefore seek to minimize the fluid disturbance that they produce. By means of particle image velocimetry, we describe the fluid disturbances produced by feeding and swimming in zooplankton with diverse propulsion mechanis...

  15. Improved Method for Determining Bacterial Filtration Rates in Zooplankton

    OpenAIRE

    Marvalin, Olivier; Lazarek, Stanislaw

    1988-01-01

    Filtration rates were determined for a natural population of zooplankton grazers (Bosmina longirostris [Müll.], Cyclops vicinus vicinus [Ulianine], Acanthodiaptomus denticornis [Wierz.], and Daphnia longispina [Müll.]) by using 3H-labeled bacteria as food for these organisms. There was a relationship between filtration rates of the major zooplankton grazers and the prevailing algal and bacterial composition in the lake water. Low filtration rates were obtained in the presence of colonial and ...

  16. Climate Impacts on Zooplankton Population Dynamics in Coastal Marine Ecosystems

    OpenAIRE

    Harold P. Batchelder; Daly, Kendra L.; Cabell S. Davis; Rubao Ji; Mark D. Ohman; Peterson, William T.; Runge, Jeffrey A.

    2013-01-01

    The 20-year US GLOBEC (Global Ocean Ecosystem Dynamics) program examined zooplankton populations and their predators in four coastal marine ecosystems. Program scientists learned that environmental controls on zooplankton vital rates, especially the timing and magnitude of reproduction, growth, life-cycle progression, and mortality, determine species population dynamics, seasonal and spatial distributions, and abundances. Improved knowledge of spatial-temporal abundance and distribution of in...

  17. On autumn zooplankton of Semipalatinsk test site water-bodies

    International Nuclear Information System (INIS)

    The autumn zooplankton in six water-bodies with mineralization diapason from 0.27 to 343.0 g/l was investigated. The species composition and number of structural characteristics were determined. The state of the zooplankton community by biodiversity and development indices is determined as normal. The observed increase of body dimensions in some species of Rotatoria and Microcrustacea requires the additional research. (author)

  18. Ecology and abundance of zooplankton in Karanja reservoir

    OpenAIRE

    Majagi, Shashikanth; Vijaykumar, K.

    2008-01-01

    The present work aims to study the Zooplankton seasonal distribution and diversity in Karanja reservoir, Bidar district for the period of two years from October 2001 to September 2003. We have recorded 36 species of which, 15 species belongs to rotifera, 11 species belongs to cladocera, nine species belongs to copepoda and ostracoda three species. Among zooplankton, particularly rotifera was the dominant group throughout the study period and highest count was recorded in the month of March 20...

  19. High Mortality of Red Sea Zooplankton under Ambient Solar Radiation

    OpenAIRE

    Al-Aidaroos, Ali M.; El-Sherbiny, Mohsen M. O.; Satheesh, Sathianeson; Mantha, Gopikrishna; Agust?, Susana; Carreja, Beatriz; Duarte, Carlos M.

    2014-01-01

    High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiatio...

  20. Planet Migration

    OpenAIRE

    Thommes, Edward W.; Lissauer, Jack J.

    2010-01-01

    Planet migration is the process by which a planet's orbital radius changes in time. The main agent for causing gas giant planet migration is the gravitational interaction of the young planet with the gaseous disk from which it forms. We describe the migration rates resulting from these interactions based on a simple model for disk properties. These migration rates are higher than is reasonable for planet survival. We discuss some proposed models for which the migration rates...

  1. Assessment of Zooplankton Community Composition along a Depth Profile in the Central Red Sea

    KAUST Repository

    Pearman, John K.

    2015-07-17

    The composition of zooplankton in the water column has received limited attention in the main body of the Red Sea and this study investigates the change in the community both spatially and temporally across 11 stations in the central Red Sea. Using molecular methods to target the v9 region of the 18S rRNA gene a total of approximately 11.5 million reads were sequenced resulting in 2528 operational taxonomic units (OTUs) at 97% similarity. The phylum Arthropoda dominated in terms of reads accounting for on average 86.2% and 65.3% for neuston nets and vertical multinets respectively. A reduction in the number of OTUs was noticed with depth for both total metazoa and Maxillopoda whilst there was also a significant change in the composition of the Maxillopoda community. The genus Corycaeus had a higher proportion of reads in the epipelagic zone with Pleuromamma becoming increasingly dominant with depth. No significant difference was observed in the community between night and day sampling however there was a significant difference in the zooplankton community between two sampling periods separated by 10 days.

  2. Diel vertical migrations of bathypelagic perch fry.

    Czech Academy of Sciences Publication Activity Database

    ?ech, Martin; Kratochvíl, Michal; Kube?ka, Jan; Draštík, Vladislav; Mat?na, Josef

    2005-01-01

    Ro?. 66, ?. 3 (2005), s. 685-702. ISSN 0022-1112 R&D Projects: GA AV ?R(CZ) IAA6017201 Institutional research plan: CEZ:AV0Z60170517 Keywords : Slapy Reservoir * fry distribution * echosounder Subject RIV: GL - Fishing Impact factor: 1.188, year: 2005

  3. Impacts of ontogenetically migrating copepods on downward carbon flux in the western subarctic Pacific Ocean

    Science.gov (United States)

    Kobari, Toru; Steinberg, Deborah K.; Ueda, Ai; Tsuda, Atsushi; Silver, Mary W.; Kitamura, Minoru

    2008-07-01

    To evaluate the impacts of ontogenetically (seasonally) migrating copepods on carbon transport to the mesopelagic zone, we investigated depth distribution, population structure, and feeding activity of the ontogentic copepod community in the western subarctic Pacific Ocean from day-night pairs of zooplankton samples down to 1000 m during the VERtical Transport In the Global Ocean (VERTIGO) program. Over the 31 July-16 August 2005 study period, the biomass of Neocalanus cristatus and Neocalanus plumchrus predominated in the near surface waters, while Neocalanus flemingeri was already dormant at depth. We observed a strong diel migration for Metridia pacifica, and a seasonal downward migration for Eucalanus bungii. Based on gut pigment analysis, ingestion rate of the copepod community was 214-375 mg C m -2 day -1, which was equal to 26-37% of the concurrent primary production. However, comparison of grazing estimated from gut pigments to calculated carbon demand of the copepod community indicates that phytoplankton comprised 37-59% of the ingested carbon. Thus, the copepod community appears to have also relied on detritus and microzooplankton for their nutrition, likely because primary production during this time was dominated by picophytoplankton too small to be grazed by these large copepods. Fecal pellet flux by the copepod community was estimated to account for 141-223% of the sedimentary particulate organic carbon (POC) flux at 150 m, suggesting considerable fragmentation and consumption of pellets in the upper layers. Fecal pellets alone were adequate to meet copepod carbon demand in the surface 0-150 m layer. Active carbon flux by diel migration of M. pacifica (respiration, egestion, and mortality) was 4-17 mg C m -2 day -1, equal to 6-44% of sedimentary POC flux at 150 m. Active carbon flux by N. flemingeri ontogenetic migration (i.e., respiration and mortality at depth) contributed 246 mg C m -2 year -1, equal to 9% of sedimentary POC flux at 1000 m. The imminent downward migration of N. cristatus and N. plumchrus would lead to an additional ontogenetic carbon flux on the order of 1719 mg C m -2 year -1. Copepod fecal pellet transport and active transport by diel and ontogenetic migration are thus important carbon fluxes during a season dominated by small phytoplankton, and ontogenetic migrants in the subarctic Pacific Ocean play a relatively more important role in active carbon flux compared with other open-ocean regions.

  4. Zooplankton production, composition and diversity in the coastal waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Padmavati, G.

    Spatial and temporal variability in zooplankton production, composition and diversity in the coastal waters of Goa were studied. Zooplankton production was bimodal with primary peak during September-October and secondary peak during March...

  5. Association of the stramenopilan protists, the aplanochytrids, with zooplankton of the equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, V.; Raghukumar, S.

    are widespread in coastal and oceanic waters, it is possible that they are also associated with pelagic zooplankton. This study examines their occurrence in zooplankton from equatorial waters of the Indian Ocean. A total of 171 of 2100 individual specimens...

  6. Zooplankton of the southwest coast of India: abundance, composition, temporal and spatial variability in 1987

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Haridas, P.; Ramaiah, Neelam; Achuthankutty, C.T.

    During early southwest and northeast monsoon periods of 1967, zooplankton standing stocks and abundances were high all along the west coast of India. Swarms of zooplankton were common in the shelf areas resulting in a low diversity-high biomass...

  7. Cell Migration

    OpenAIRE

    Trepat, Xavier; Chen, Zaozao; Jacobson, Ken

    2012-01-01

    Cell migration is fundamental to establishing and maintaining the proper organization of multicellular organisms. Morphogenesis can be viewed as a consequence, in part, of cell locomotion, from large-scale migrations of epithelial sheets during gastrulation, to the movement of individual cells during development of the nervous system. In an adult organism, cell migration is essential for proper immune response, wound repair, and tissue homeostasis, while aberrant cell migration is found in va...

  8. 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

    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 sampling does not collect marine snow quantitatively and cannot resolve so-called thin layers in which this interaction occurs. Hence, field evidence for the importance of the marine snow?zooplankton link is scarce. Here we employed a Video Plankton Recorder (VPR) to quantify small-scale (metres) vertical distribution patterns of fragile marine snow aggregates and zooplankton in the Baltic Sea during late spring 2002. By using this non-invasive optical sampling technique we recorded a peak in copepod abundance (ca. 18 ind. l?1) associated with a pronounced thin layer (50 to 55 m) of marine snow (maximum abundance of 28 particles l?1), a feature rarely resolved. We provide indirect evidence of copepods feeding on marine snow by computing a spatial overlap index that indicated a strong positively correlated distribution pattern within the thin layer. Furthermore we recorded images of copepods attached 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

  9. Irradiation effect on zooplankton eggs applied by bremsstrahlung induced from pulsed intense electron beam

    International Nuclear Information System (INIS)

    We have considered an irradiation effect on zooplankton eggs applied by bremsstrahlung induced from pulsed intense electron beam. Zooplankton eggs about 200 have been successfully inactivated using a bremsstrahlung at 3 kGy. We found that 63.9% of zooplankton eggs are inactivated by bremsstrahlung irradiation. It was the increase of 30 points in comparisons with 33.3% of zooplankton eggs inactivated for non-irradiation case. (author)

  10. Zooplankton-mediated nutrient limitation patterns in marine phytoplankton: an experimental approach with natural communities

    OpenAIRE

    Trommer, Gabriele; Pondaven, Philippe; Siccha, Michael; Stibor, Herwig

    2012-01-01

    Zooplankton nutrient recycling has been shown to substantially affect nutrient availability for phytoplankton. However, investigations are required to determine whether zooplankton also influence nutrient limitation in marine phytoplankton communities, and whether grazing by different zooplankton groups results in different patterns of phytoplankton nutrient limitation. We performed laboratory experiments under different nutrient supply conditions on a variety of phytoplankton communities wit...

  11. High mortality of Red Sea zooplankton under ambient solar radiation.

    Science.gov (United States)

    Al-Aidaroos, Ali M; El-Sherbiny, Mohsen M O; Satheesh, Sathianeson; Mantha, Gopikrishna; Agust?, Susana; Carreja, Beatriz; Duarte, Carlos M

    2014-01-01

    High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiation doses with zooplankton mortality were evaluated by exposing organisms, enclosed in quartz bottles, allowing all the wavelengths of solar radiation to penetrate, to five different levels of ambient solar radiation (100%, 21.6%, 7.2%, 3.2% and 0% of solar radiation). The maximum mortality rates under ambient solar radiation levels averaged (±standard error of the mean, SEM) 18.4±5.8% h(-1), five-fold greater than the average mortality in the dark for the eight taxa tested. The UV-B radiation required for mortality rates to reach ½ of maximum values averaged (±SEM) 12±5.6 h(-1)% of incident UVB radiation, equivalent to the UV-B dose at 19.2±2.7 m depth in open coastal Red Sea waters. These results confirm that Red Sea zooplankton are highly vulnerable to ambient solar radiation, as a consequence of the combination of high incident radiation and high water transparency allowing deep penetration of damaging UV-B radiation. These results provide evidence of the significance of ambient solar radiation levels as a stressor of marine zooplankton communities in tropical, oligotrophic waters. Because the oligotrophic ocean extends across 70% of the ocean surface, solar radiation can be a globally-significant stressor for the ocean ecosystem, by constraining zooplankton use of the upper levels of the water column and, therefore, the efficiency of food transfer up the food web in the oligotrophic ocean. PMID:25309996

  12. Reaction of fresh water zooplankton community to chronic radiation exposure

    International Nuclear Information System (INIS)

    The characteristic features of ecological community as a whole and cenosis of zooplankton organisms as part of it determine the intensity of the processes of self-purification of water and the formation of a particular body of water. Identifying features of the structure and composition of the zooplankton community of aquatic ecosystems exposed to different levels of radiation exposure, it is necessary to identify patterns of changes in zooplankton and hydro-biocenosis as a whole. Industrial reservoirs, the storage of liquid low-level radioactive waste 'Mayak' for decades, have high radiation load. A large range of levels of radioactive contamination (total volume beta-activity in water varies from 2.2x103 to 2.3x107 Bq/l, total volume alpha-activity - from 2.6x10-1 to 3.1x103 Bq/l) provides a unique opportunity to study ecosystems in a number of reservoirs with increasing impact of radiation factor. We studied five reservoirs that were used as the storage of low-and intermediate-level liquid radioactive waste pond and one comparison water body. In parallel with zooplankton sampling water samples were collected for hydro-chemical analysis. 41 indicators were analysed in order to assess the water chemistry. To determine the content of radionuclides in the various components of the ecosystem samples were collected from water, bottom sediments and plankton. Sampling of zooplankton for the quantitative analysis was performed using the method of weighted average auto bathometer. Apshteyn's plankton net of the surface horizon was used for qualitative analysis of the species composition of zooplankton. Software package ERICA Assessment Tool 2012 was used for the calculation of the absorbed dose rate. Species diversity and biomass of zooplankton, the share of rotifers in the number of species, abundance and biomass decrease with the increase of the absorbed dose rate and salinity. The number of species in a sample decreases with the increase of the absorbed dose according to the S-shaped function. 5 % reduction in species diversity corresponds to 1.1x102 mcGy/hr, 50 % reduction - 1.1x103 mcGy/hr. Margalef's index and Shannon's index were 5% lower at 9.1x102 mcGy/hr and 50% lower at 1.7x103 mcGy/hr, that points to simplified communication in the plankton community. Quantitative indicators of zooplankton are less sensitive to changes in the aquatic environment under study than indicators of species richness and the complexity of relationships in the community. Document available in abstract form only. (authors)

  13. The effect of radial migration on galactic disks

    International Nuclear Information System (INIS)

    We study the radial migration of stars driven by recurring multi-arm spiral features in an exponential disk embedded in a dark matter halo. The spiral perturbations redistribute angular momentum within the disk and lead to substantial radial displacements of individual stars, in a manner that largely preserves the circularity of their orbits and that results, after 5 Gyr (?40 full rotations at the disk scale length), in little radial heating and no appreciable changes to the vertical or radial structure of the disk. Our results clarify a number of issues related to the spatial distribution and kinematics of migrators. In particular, we find that migrators are a heavily biased subset of stars with preferentially low vertical velocity dispersions. This 'provenance bias' for migrators is not surprising in hindsight, for stars with small vertical excursions spend more time near the disk plane, and thus respond more readily to non-axisymmetric perturbations. We also find that the vertical velocity dispersion of outward migrators always decreases, whereas the opposite holds for inward migrators. To first order, newly arrived migrators simply replace stars that have migrated off to other radii, thus inheriting the vertical bias of the latter. Extreme migrators might therefore be recognized, if present, by the unexpectedly small amplitude of their vertical excursions. Our results show that migration, understood as changes in angular momentum that preserve circularity, can strongly affect the thin disk, but cast doubts on models that envision the Galactic thick disk as a relic of radial migration.

  14. THE VERTICAL

    Science.gov (United States)

    Albert, Stephen L.; Spencer, Jeffrey B.

    1994-01-01

    'THE VERTICAL' computer keyboard is designed to address critical factors which contribute to Repetitive Motion Injuries (RMI) (including Carpal Tunnel Syndrome) in association with computer keyboard usage. This keyboard splits the standard QWERTY design into two halves and positions each half 90 degrees from the desk. In order to access a computer correctly. 'THE VERTICAL' requires users to position their bodies in optimal alignment with the keyboard. The orthopaedically neutral forearm position (with hands palms-in and thumbs-up) reduces nerve compression in the forearm. The vertically arranged keypad halves ameliorate onset occurrence of keyboard-associated RMI. By utilizing visually-reference mirrored mylar surfaces adjustable to the user's eye, the user is able to readily reference any key indicia (reversed) just as they would on a conventional keyboard. Transverse adjustability substantially reduces cumulative musculoskeletal discomfort in the shoulders. 'THE VERTICAL' eliminates the need for an exterior mouse by offering a convenient finger-accessible curser control while the hands remain in the vertically neutral position. The potential commercial application for 'THE VERTICAL' is enormous since the product can effect every person who uses a computer anywhere in the world. Employers and their insurance carriers are spending hundreds of millions of dollars per year as a result of RMI. This keyboard will reduce the risk.

  15. Detecting response patterns of zooplankton to environmental parameters in shallow freshwater wetlands: discovery of the role of macrophytes as microhabitat for epiphytic zooplankton

    Directory of Open Access Journals (Sweden)

    Jong-Yun Choi

    2015-05-01

    Full Text Available Freshwater macrophytes improve the structural heterogeneity of microhabitats in water, often providing an important habitat for zooplankton. Some studies have focused on the overall influence of macrophytes on zooplankton, but the effects of macrophyte in relation to different habitat characteristics of zooplankton (e.g., epiphytic and pelagic have not been intensively studied. We hypothesized that different habitat structures (i.e., macrophyte habitat would strongly affect zooplankton distribution. We investigated zooplankton density and diversity, macrophyte characteristics (dry weight and species number, and environmental parameters in 40 shallow wetlands in South Korea. Patterns in the data were analyzed using a self-organizing map (SOM, which extracts information through competitive and adaptive properties. A total of 20 variables (11 environmental parameters and 9 zooplankton groups were patterned onto the SOM. Based on a U-matrix, 3 clusters were identified from the model. Zooplankton assemblages were positively related to macrophyte characteristics (i.e., dry weight and species number. In particular, epiphytic species (i.e., epiphytic rotifers and cladocerans exhibited a clear relationship with macrophyte characteristics, while large biomass and greater numbers of macrophyte species supported high zooplankton assemblages. Consequently, habitat heterogeneity in the macrophyte bed was recognized as an important factor to determine zooplankton distribution, particularly in epiphytic species. The results indicate that macrophytes are critical for heterogeneity in lentic freshwater ecosystems, and the inclusion of diverse plant species in wetland construction or restoration schemes is expected to generate ecologically healthy food webs.

  16. Changes in fecal pellet characteristics with depth as indicators of zooplankton repackaging of particles in the mesopelagic zone of the subtropical and subarctic North Pacific Ocean

    Science.gov (United States)

    Wilson, Stephanie E.; Steinberg, Deborah K.; Buesseler, Ken O.

    2008-07-01

    We investigated how fecal pellet characteristics change with depth in order to quantify the extent of particle repackaging by mesopelagic zooplankton in two contrasting open-ocean systems. Material from neutrally buoyant sediment traps deployed in the summer of 2004 and 2005 at 150, 300, and 500 m was analyzed from both a mesotrophic (Japanese time-series station K2) and an oligotrophic (Hawaii Ocean Time series—HOT station ALOHA) environment in the Pacific Ocean as part of the VERtical Transport In the Global Ocean (VERTIGO) project. We quantified changes in the flux, size, shape, and color of particles recognizable as zooplankton fecal pellets to determine how these parameters varied with depth and location. Flux of K2 fecal pellet particulate organic carbon (POC) at 150 and 300 m was four to five times higher than at ALOHA, and at all depths, fecal pellets were two to five times larger at K2, reflective of the disparate zooplankton community structure at the two sites. At K2, the proportion of POC flux that consisted of fecal pellets generally decreased with depth from 20% at 150 m to 5% at 500 m, whereas at ALOHA this proportion increased with depth (and was more variable) from 14% to 35%. This difference in the fecal fraction of POC with increasing depth is hypothesized to be due to differences in the extent of zooplankton-mediated fragmentation (coprohexy) and in zooplankton community structure between the two locations. Both regions provided indications of sinking particle repackaging and zooplankton carnivory in the mesopelagic. At ALOHA, this was reflected in a significant increase in the mean flux of larvacean fecal pellets from 150 to 500 m of 3-46 ?g C m -2 d -1, respectively, and at K2 a large peak in larvacean mean pellet flux at 300 m of 3.1 mg C m -2 d -1. Peaks in red pellets produced by carnivores occurred at 300 m at K2, and a variety of other fecal pellet classes showed significant changes in their distribution with depth. There was also evidence of substantially higher pellet fragmentation at K2 with nearly double the ratio of broken:intact pellets at 150 and 300 m (mean of 67% and 64%, respectively) than at ALOHA where the proportion of broken pellets remained constant with depth (mean 35%). Variations in zooplankton size and community structure within the mesopelagic zone can thus differentially alter the transfer efficiency of sinking POC.

  17. Climate Impacts on Zooplankton Population Dynamics in Coastal Marine Ecosystems

    Directory of Open Access Journals (Sweden)

    Harold P. Batchelder

    2013-12-01

    Full Text Available The 20-year US GLOBEC (Global Ocean Ecosystem Dynamics program examined zooplankton populations and their predators in four coastal marine ecosystems. Program scientists learned that environmental controls on zooplankton vital rates, especially the timing and magnitude of reproduction, growth, life-cycle progression, and mortality, determine species population dynamics, seasonal and spatial distributions, and abundances. Improved knowledge of spatial-temporal abundance and distribution of individual zooplankton taxa coupled with new information linking higher trophic level predators (salmon, cod, haddock, penguins, seals to their prey yielded mechanistic descriptions of how climate variation impacts regionally important marine resources. Coupled ecological models driven by improved regional-scale climate scenario models developed during GLOBEC enable forecasts of plausible future conditions in coastal ecosystems, and will aid and inform decision makers and communities as they assess, respond, and adapt to the effects of environmental change. Multi-region synthesis revealed that conditions in winter, before upwelling, or seasonal stratification, or ice melt (depending on region had significant and important effects that primed the systems for greater zooplankton population abundance and productivity the following spring-summer, with effects that propagated to higher trophic levels.

  18. Vertical distribution of phytoplankton functional groups in a tropical shallow lake: driving forces on a diel scale / Distribuição vertical de grupos funcionais fitoplanctônicos em um lago tropical raso: forças direcionadoras em escala nictemeral

    Scientific Electronic Library Online (English)

    Luciana Gomes, Barbosa; Paulina Maria Maia, Barbosa; Francisco Antonio Rodrigues, Barbosa.

    2011-03-01

    Full Text Available OBJETIVO: Analisar a distribuição vertical dos grupos funcionais fitoplanctônicos em dois ciclos nictemerais em um lago tropical monomítico raso; MÉTODOS: As amostragens das variáveis abióticas, comunidades fitoplanctônica e zooplanctônica foram realizadas a intervalos de 3 horas ao longo de 24 hora [...] s em perfis verticais, nos períodos de estratificação (fevereiro) e de circulação (julho); RESULTADOS: A elevada estabilidade térmica e a atelomixia parcial favoreceram a coexistência de grupos funcionais sensíveis a desestratificação N A e F, compostos por desmidias e clorofícias cocoides e pelos grupos S2 e Lo, persistentes durante a circulação, e compostos por cianobactérias filamentosas não fixadoras de N2 e dinoflagelados, respectivamente. A descontinuidade na distribuição vertical dos grupos funcionais com dominância de N A e F no epilímnio e de R e Lo no metalímnio e hipolímnio foi característica da estratificação, e diferenças entre períodos diurno e noturno não foram significativas. CONCLUSÕES: A redução em até 80% da biomassa do grupo NA durante a circulação indica a influência da estabilidade térmica e atelomixia parcial como fatores determinantes na compartimentalização dos grupos funcionais, restringindo a migração vertical diurna (MVD) e a perda por sedimentação durante a estratificação. Abstract in english AIM: This study analyzed the vertical distribution of phytoplankton functional groups in two diel cycles in a warm monomictic shallow tropical lake; METHODS: Sampling of the abiotic variables, phytoplankton and zooplankton communities was performed at intervals of 3 hours over 24 hours in vertical p [...] rofiles, in the stratification (February) and circulation (July) periods; RESULTS: The high thermal stability and the partial atelomixis favored the coexistence of functional groups that are sensitive to destratification, N A and F, composed by desmids and Chlorophyceae coccoids, and groups S2 and Lo, which persisted during the circulation, and were composed by filamentous cyanobacteria which do not fix N2 and dinoflagellates, respectively. The discontinuity in the vertical distribution of the functional groups, with dominance of N A and F in the epilimnion and R and Lo in the metalimnion and hypolimnion, was characteristic of the stratification, and differences between the daytime and nighttime periods were not significant. CONCLUSIONS: The reduction of 80% of the biomass of the NA group during the mixing period indicates the influence of thermal stability and partial atelomixis as determinant factors in the compartmentalization of functional groups, restricting daytime vertical migration (DVM) and loss by sedimentation during the stratification period.

  19. Italian migration

    OpenAIRE

    DEL BOCA, Daniela; Venturini, Alessandra

    2003-01-01

    Italy is a country with a long history of emigration and a very short experience of immigration. The paper first surveys the Italian emigration pattern describing the characteristics of the Italian emigrants (age, sex, skill level), their area of origins and the directions of their movement. The determinants of the migration choice are then analyzed as well as the policies affecting the decision to migrate. The end of the first section provides an analysis of the emigration effects in the are...

  20. Migration chemistry

    International Nuclear Information System (INIS)

    Migration chemistry, the influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour of pollutants in the environment, is an interplay between the actual natur of the pollutant and the characteristics of the environment, such as pH, redox conditions and organic matter content. The wide selection of possible pollutants in combination with varying geological media, as well as the operation of different chemical -, biochemical - and physico-chemical reactions compleactes the prediction of the influence of these processes on the mobility of pollutants. The report summarizes a wide range of potential pollutants in the terrestrial environment as well as a variety of chemical -, biochemical - and physico-chemical reactions, which can be expected to influence the migration behaviour, comprising diffusion, dispersion, convection, sorption/desorption, precipitation/dissolution, transformations/degradations, biochemical reactions and complex formation. The latter comprises the complexation of metal ions as well as non-polar organics to naturally occurring organic macromolecules. The influence of the single types of processes on the migration process is elucidated based on theoretical studies. The influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour is unambiguous, as the processes apparently control the transport of pollutants in the terrestrial environment. As the simple, conventional KD concept breaks down, it is suggested that the migration process should be described in terms of the alternative concepts chemical dispersion, average-elution-time and effective retention. (AB) (134 refs.)

  1. Coprophagy in copepods and in a natural zooplankton community

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; KiØrboe, Thomas

    Sediment trap studies have revealed that often only a minor fraction of the zooplankton fecal pellet production leave the upper ocean, and it has been suggested that copepod grazing on pellets (coprophagy) is the reason for this. A simple model is here used to estimate rate of coprophagy from lab and field observations. In the lab Acartia tonsa and Temora longicornis have coprophagous behavior and clear fecal pellets at a rate of 10-15 ml/female/d. Observations of fecal pellet production, sedimentation, and abundance collected during a 10-d late summer study in the North Sea revealed that less than 5 % of the fecal pellet production in the upper 50 m was lost as flux below 50 m depth. Estimates of coprophagy rates showed, however, that the zooplankton community > 200 um could account for only a few percent of the fecal pellet loss. Thus, plankton organisms < 200 ?m must be responsible for the degradation of the fecal pellets

  2. Resurrecting the ghost of competition past with dormant zooplankton eggs.

    Science.gov (United States)

    Steiner, Christopher F; Cáceres, Carla E; Smith, Sigrid D P

    2007-03-01

    A common prediction of evolutionary theory is that the strength of interspecific competition should decline over time among sympatric populations of competing species. Here we provide experimental evidence of historical declines in competition effects among competing zooplankton populations. Using diapausing eggs, we resurrected clones of three species of zooplankton obtained from different periods of community assembly in a single lake. We show that clones of Daphnia ambigua obtained from early in assembly when D. ambigua was dominant became extinct in competition with clones of Daphnia pulicaria and Daphnia dentifera (the current lake dominants). In contrast, D. ambigua clones obtained from later in the lake's history experienced weaker competition effects and persisted with D. dentifera. While we cannot rule out the role of intraspecific competition within D. ambigua, our results are in line with the view that natural selection favors reduced interaction strength among co-occurring species, facilitating coexistence and population persistence. PMID:17238127

  3. Estimation of zooplankton mortality caused by an Arctic glacier outflow

    Directory of Open Access Journals (Sweden)

    Marek J. Zaj±czkowski

    2001-09-01

    Full Text Available The outflow of freshwater from underwater channels in the Kongsbreen tidal glacier in Kongsfjorden, Svalbard, 79oN, was measured as 138.8 m3 s-1 at the peak of the melting season. Experiments on local marine plankton mortality show that when exposed to salinities below 9 PSU, all copepods die within 15 minutes. We estimate that during 100 days of the melting season, as many as 85 tonnes wet weight (WW of plankton is removed from the water column due to osmotic shock, which makes up 15% of the standing zooplankton biomass of the fjord. The dead zooplankton sinks after exposure to low salinities and is probably an important food source for scavenging benthic fauna in the fjord. This mechanism could be responsible for the high numbers of Onisimus caricus near the glacier front.

  4. Ecological considerations on the lake Bolonha zooplankton, Belém, Pará, Brazil

    Directory of Open Access Journals (Sweden)

    Nuno Filipe Alves Correia de Melo

    2006-04-01

    Full Text Available Zooplankton population of the lake Bolonha were sampled in three stations in September of 1993. The objective was to determine the basic characteristics of the populations, as the composition and density of species, besides some environmental parameters. Fifty six species were determined, thirty of them were of Rotifera, nineteen Cladocera and seven Copepoda. Among Rotifera, the most frequent organisms were Brachionus zahniseri gessneri, Polyarthra vulgaris and Tricocerca similis, while enter Cladocera, Bosminopsis deitersi and Bosmina hagmanni were the most important in density terms. For Copepoda, the nauplii and copepodits they were the ones that presented the largerst densities, but Oithona amazonica and Notodiaptomus amazonicus deserve to be registered for they have also presented a great density. The lake Bolonha came with a great diversity of zooplanktonic organisms, needing, meantime of more intensive studies, because that number in biodiversity terms should increase considerable.

  5. Reaction of fresh water zooplankton community to chronic radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Osipov, D.; Pryakhin, E. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation); Ivanov, I. [FSUE Mayak PA (Russian Federation)

    2014-07-01

    The characteristic features of ecological community as a whole and cenosis of zooplankton organisms as part of it determine the intensity of the processes of self-purification of water and the formation of a particular body of water. Identifying features of the structure and composition of the zooplankton community of aquatic ecosystems exposed to different levels of radiation exposure, it is necessary to identify patterns of changes in zooplankton and hydro-biocenosis as a whole. Industrial reservoirs, the storage of liquid low-level radioactive waste 'Mayak' for decades, have high radiation load. A large range of levels of radioactive contamination (total volume beta-activity in water varies from 2.2x10{sup 3} to 2.3x10{sup 7} Bq/l, total volume alpha-activity - from 2.6x10{sup -1} to 3.1x10{sup 3} Bq/l) provides a unique opportunity to study ecosystems in a number of reservoirs with increasing impact of radiation factor. We studied five reservoirs that were used as the storage of low-and intermediate-level liquid radioactive waste pond and one comparison water body. In parallel with zooplankton sampling water samples were collected for hydro-chemical analysis. 41 indicators were analysed in order to assess the water chemistry. To determine the content of radionuclides in the various components of the ecosystem samples were collected from water, bottom sediments and plankton. Sampling of zooplankton for the quantitative analysis was performed using the method of weighted average auto bathometer. Apshteyn's plankton net of the surface horizon was used for qualitative analysis of the species composition of zooplankton. Software package ERICA Assessment Tool 2012 was used for the calculation of the absorbed dose rate. Species diversity and biomass of zooplankton, the share of rotifers in the number of species, abundance and biomass decrease with the increase of the absorbed dose rate and salinity. The number of species in a sample decreases with the increase of the absorbed dose according to the S-shaped function. 5 % reduction in species diversity corresponds to 1.1x10{sup 2} mcGy/hr, 50 % reduction - 1.1x10{sup 3} mcGy/hr. Margalef's index and Shannon's index were 5% lower at 9.1x10{sup 2} mcGy/hr and 50% lower at 1.7x10{sup 3} mcGy/hr, that points to simplified communication in the plankton community. Quantitative indicators of zooplankton are less sensitive to changes in the aquatic environment under study than indicators of species richness and the complexity of relationships in the community. Document available in abstract form only. (authors)

  6. Metals in coastal zooplanktons - A coastal living resource hazard

    Digital Repository Service at National Institute of Oceanography (India)

    Paimpillil, J.S.; Joseph, T.; Rejomon, G.; Gerson, V.J.

    by planktonic species. Keywords: Trace metals, Zooplankton, Bioaccumulation. INTRODUCTION Trace metal accumulation in aquatic consumers is of great interest to ecologists and to environmentalists for evaluating the fate and effects of this in the marine food web... these are more concentrated within the tissues as they go to higher trophic levels. Tissue levels of heavy metals may often relate to longevity and growth rate of the organisms rather than its position in the food web (Landner, 1975). The main effects due...

  7. Fatty acid transformation in zooplankton: from seston to benthos

    DEFF Research Database (Denmark)

    Tiselius, Peter; Hansen, Benni Winding; Calliari, Danilo

    2012-01-01

    All organic matter, fatty acids (FA) in particular, is transformed in the pelagic plankton food web before reaching fishes or benthic organisms. Mesozooplankton (0.2 to 2 mm) is the main conduit for FA transfer, and FA profiles in sedimenting matter should therefore be significantly affected by its activity. To test this hypothesis, we sampled seston, zooplankton and sediment trap material for FA analysis during 5 campaigns spanning 4 seasons at a coastal site on the west coast of Sweden. Satura...

  8. Ingestion of Microplastics by Zooplankton in the Northeast Pacific Ocean.

    Science.gov (United States)

    Desforges, Jean-Pierre W; Galbraith, Moira; Ross, Peter S

    2015-10-01

    Microplastics are increasingly recognized as being widespread in the world's oceans, but relatively little is known about ingestion by marine biota. In light of the potential for microplastic fibers and fragments to be taken up by small marine organisms, we examined plastic ingestion by two foundation species near the base of North Pacific marine food webs, the calanoid copepod Neocalanus cristatus and the euphausiid Euphausia pacifia. We developed an acid digestion method to assess plastic ingestion by individual zooplankton and detected microplastics in both species. Encounter rates resulting from ingestion were 1 particle/every 34 copepods and 1/every 17 euphausiids (euphausiids > copepods; p = 0.01). Consistent with differences in the size selection of food between these two zooplankton species, the ingested particle size was greater in euphausiids (816 ± 108 ?m) than in copepods (556 ± 149 ?m) (p = 0.014). The contribution of ingested microplastic fibres to total plastic decreased with distance from shore in euphausiids (r (2) = 70, p = 0.003), corresponding to patterns in our previous observations of microplastics in seawater samples from the same locations. This first evidence of microplastic ingestion by marine zooplankton indicate that species at lower trophic levels of the marine food web are mistaking plastic for food, which raises fundamental questions about potential risks to higher trophic level species. One concern is risk to salmon: We estimate that consumption of microplastic-containing zooplankton will lead to the ingestion of 2-7 microplastic particles/day by individual juvenile salmon in coastal British Columbia, and ?91 microplastic particles/day in returning adults. PMID:26066061

  9. Flow disturbances generated by feeding and swimming zooplankton

    DEFF Research Database (Denmark)

    KiØrboe, Thomas; Jiang, Haisong

    2014-01-01

    Interactions between planktonic organisms, such as detection of prey, predators, and mates, are often mediated by fluid signals. Consequently, many plankton predators perceive their prey from the fluid disturbances that it generates when it feeds and swims. Zooplankton should therefore seek to minimize the fluid disturbance that they produce. By means of particle image velocimetry, we describe the fluid disturbances produced by feeding and swimming in zooplankton with diverse propulsion mechanisms and ranging from 10-µm flagellates to greater than millimeter-sized copepods. We show that zooplankton, in which feeding and swimming are separate processes, produce flow disturbances during swimming with a much faster spatial attenuation (velocity u varies with distance r as u ? r?3 to r?4) than that produced by zooplankton for which feeding and propulsion are the same process (u ? r?1 to r?2). As a result, the spatial extension of the fluid disturbance produced by swimmers is an order of magnitude smaller than that produced by feeders at similar Reynolds numbers. The “quiet” propulsion of swimmers is achieved either through swimming erratically by short-lasting power strokes, generating viscous vortex rings, or by “breast-stroke swimming.” Both produce rapidly attenuating flows. The more “noisy” swimming of those that are constrained by a need to simultaneously feed is due to constantly beating flagella or appendages that are positioned either anteriorly or posteriorly on the (cell) body. These patterns transcend differences in size and taxonomy and have thus evolved multiple times, suggesting a strong selective pressure to minimize predation risk.

  10. Midsummer crustacean zooplankton communities in acid-stressed lakes

    Energy Technology Data Exchange (ETDEWEB)

    Sprules, W.G.

    1975-01-01

    The distribution of limnetic crustacean zooplankton species and species associations in 47 industrially acidified lakes of the La Cloche Mountains, Ontario, are examined. PH, which ranged from 3.8 to 7.0, and to a lesser extent lake area and depth are the major determinants of the structure of these communities. Mesocyclops edax, Cyclops bicuspidatus thomasi, Diaptomus minutus, Holopedium gibberum, Diaphanosoma leuchtenbergianum, and Bosmina sp. were common species which occurred over the entire pH range. Tropocyclops prasinus mexicanus, Epischura lacustris, Diaptomus oregonensis, Leptodora kindtii, Daphnia galeata mendotae, D. retrocurva, D. ambigua, and D. longiremis plus some other rare species making a total of 64% of all species found never or rarely occurred below pH 5.0. Polyphemus pediculus, Daphnia catawba, and D. pulicaria were found primarily in lakes with low pH. An increase in the complexity of the zooplankton communities with increasing pH was evident. Above pH 5.0 the communities contained 9-16 species with three or four dominant species; in lakes with pH 5.0 or less the communities comprised one to seven species with only one or two dominants. Compared with relatively unspoiled lakes of similar morphometry in northwestern Ontario (Ela Lakes) the La Cloche Lakes have unusually simple zooplankton associations, particularly the very acidic lakes. In the La Cloche Lakes the group of six species occurred most frequently in lakes with pH above 5.0 although it maintained its integrity even down to pH 5.0. It is concluded that pH has a great effect on these zooplankton communities, primarily in lakes with pH below 5.0 where many species are completely eliminated and even tolerant species become progressively rarer until in some lakes a single species (D. minutus) remains.

  11. Effect of hydrodynamic cavitation on zooplankton: A tool for disinfection

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Anil, A.C.; Venkat, K.; Gaonkar, C.; Kolwalkar, J.; Khandeparker, L.; Desai, D.V.; Mahulkar, A.V.; Ranade, V.V.; Pandit, A.B.

    . But it is seen in the present study that the required turbulent shear stress can be generated in a very energy efficient manner by volumetric oscillations of the cavities in the downstream orifice plates by creating hydrodynamic cavitating conditions. 7.... Energy efficiency of zooplankton mortality using orifice plate was seen to be much higher than that in partially closed valve or in pump. 4. Theoretical model for quantifying the cavitational intensity and the extent of microbial cell disruption has been...

  12. Zooplankton fecal pellets link fossil fuel and phosphate deposits

    Science.gov (United States)

    Porter, K.G.; Robbins, E.I.

    1981-01-01

    Fossil zooplankton fecal pellets found in thinly bedded marine and lacustrine black shales associated with phosphate, oil, and coal deposits, link the deposition of organic matter and biologically associated minerals with planktonic ecosystems. The black shales were probably formed in the anoxic basins of coastal marine waters, inland seas, and rift valley lakes where high productivity was supported by runoff, upwelling, and outwelling. Copyright ?? 1981 AAAS.

  13. Towards methodological approaches to implement the zooplankton component in “end to end” food-web models

    OpenAIRE

    Carlotti, F.; Poggiale, JC

    2009-01-01

    The modelling of marine zooplankton has made great progress over the two last decades covering a large range of representations from detailed individual processes to functional groups. A new challenge is to dynamically represent zooplankton within marine food webs coupling lower trophic levels to fish and to thereby further our understanding of the role of zooplankton in global change. In this respect, the “rhomboid strategy” (deYoung et al., 2004) has been suggested as a generic approach to ...

  14. Natural and cultivated zooplankton as food for halibut (Hippoglossus hippoglossus) larvae

    OpenAIRE

    Naas, Kjell Emil; Berg, Leif; Klungsøyr, Jarle; Pittman, Karin

    1987-01-01

    Natural zooplankton were pumped into a collector and size-fractionated. The zooplankton smaller than 350 ym were fed on a diatom dominated algal suspension cultured in 3 m deep out-door plastic bags. Halibut larvae were kept through the yolk sac stages in large temperature regulated bags, and when ready to start first feeding, they were offered both cultivated and natural zooplankton. The composition of fatty acids in growing larvae were analyzed to study the influence of dietary lipids.

  15. Ecological investigation of zooplankton abundance in the river Haraz, northeast Iran: Impact of environmental variables

    OpenAIRE

    Jafari Naser; Nabavi Mohamad Saiad; Akhavan Moslem

    2011-01-01

    The influence of physicochemical properties of Haraz river on its zooplankton composition and abundance were investigated at three sites for one year between August 2009 and July 2010. The present study records for the first time the aspects of zooplankton diversity and composition in relation to the physicochemical environment of the Haraz river. Only three groups of zooplankton were found: Rotifera with eighteen genera; Cladocera with nine and Copepoda with six genera. Rotifera was th...

  16. A global analysis of zooplankton in natural and artificial fresh waters

    OpenAIRE

    Faye L. Merrix-Jones; Stephen J. Ormerod; Stephen J. Thackeray

    2013-01-01

    Water-body size and location influence zooplankton diversity in freshwaters, but less is known about systematic variations in zooplankton community composition between natural and artificial waters on different continents. We used meta-analysis to assess how zooplankton in artificial water bodies across different biomes might differ from natural water bodies of similar size. Among 79 lakes, ponds and reservoirs (11 artificial and 68 natural), proximity to other water bodies apparently increas...

  17. STUDIES ON ZOOPLANKTONS OF GODADA LAKE OF BULDHANA DISTRICT, (M. S.) INDIA

    OpenAIRE

    Meena T. Nikam

    2012-01-01

    The plankton constitutes the basic food sources of any aquatic ecosystem, which supports fish and other aquatic animals. Zooplankton diversity is one of the most important ecological parameters in water quality assessment. Zooplanktons are good indicators of the changes in water quality because they are strongly affected by environmental conditions & respond quickly to changes in water quality. Zooplankton is the intermediate link between phytoplankton and fish. Hence qualitative a...

  18. Considerations on the biochemical composition of some freshwater zooplankton species.

    Directory of Open Access Journals (Sweden)

    Nicoletta RICCARDI

    1999-02-01

    Full Text Available The mean elemental (C, H, N and biochemical composition (lipids, carbohydrates and proteins of some abundant crustacean zooplankton species of Italian insubric lakes has been estimated by the analysis of samples collected at different seasons from various environments (Lake Maggiore, Lake Varese, Lake Comabbio, Lake Monate. From each sample an adequate number of specimens of each abundant species was sorted and analyzed by a CHN elemental analyzer. The percentage of lipids, carbohydrates and proteins and the calorific content were calculated from the elemental composition according to Gnaiger & Bitterlich (1984. Inter- and intraspecific variability of biochemical composition was quite high, while elemental composition and calorific content were less variable. An estimate of the mean elemental and biochemical composition of each species was obtained by pooling the data. These mean values have been used to estimate the pools of elements and compounds in the crustacean zooplankton of Lake Comabbio to provide an example of the importance of a multiple approach in zooplankton studies.

  19. Phytoplanktons and zooplanktons diversity in karachi coastal seawater under high and low tide during winter monsoon

    International Nuclear Information System (INIS)

    This paper represents the population density of phytoplanktons and zooplanktons recorded during the marine environmental studies at Karachi coast in the month of February 2011. Samples were collected by towing net, preserved and quantification and identification was carried out under light microscope. Twenty-three phytoplanktons species and nine zooplankton groups were recorded in the seawater from the sampling area of 10 square kilometers. Coscinodiscus and Copepods were dominant in the population of phytoplankton and zooplankton, respectively. Phytoplankton population density increased while zooplankton abundance decreased offshore from the coastline in the open sea. (author)

  20. Prestack exploding reflector modeling and migration in TI media

    KAUST Repository

    Wang, H.

    2014-01-01

    Prestack depth migration in anisotropic media, especially those that exhibit tilt, can be costly using reverse time migration (RTM). We present two-way spectral extrapolation of prestack exploding reflector modeling and migration (PERM) in acoustic transversely isotropic (TI) media. We construct systematic ways to evaluate phase angles and phase velocities in dip oriented TI (DTI), vertical TI (VTI) and tilted TI (TTI) media. Migration results from the Marmousi VTI model and the BP2007 TTI model show the feasibility of our approach.

  1. Planetary migration

    CERN Document Server

    Armitage, P J; Armitage, Philip J.

    2005-01-01

    Gravitational torques between a planet and gas in the protoplanetary disk result in orbital migration of the planet, and are likely to play an important role in the formation and early evolution of planetary systems. For masses comparable to those of observed giant extrasolar planets, the interaction with the disk is strong enough to form a gap, leading to coupled evolution of the planet and disk on a viscous time scale (Type II migration). Both the existence of hot Jupiters, and the statistical distribution of observed orbital radii, are consistent with an important role for Type II migration in the history of currently observed systems. We discuss the possibility of improving constraints on migration by including information on the host stars' metallicity, and note that migration could also form a population of massive planets at large orbital radii that may be indirectly detected via their influence on debris disks. For lower mass planets with masses of the order of that of the Earth, surface density pertu...

  2. Zooplankton data collected from zooplankton net casts from RESEARCHER I and other platforms in TOGA Area of Pacific Ocean; 16 March 1968 to 02 July 1970 (NODC Accession 9500141)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities and other data were collected using zooplankton casts in the TOGA Area of Pacific Ocean from RESEARCHER I and other platforms. Data...

  3. Zooplankton data collected from zooplankton net casts in TOGA Area - Atlantic and Indian Ocean by GAVESHANI and other platforms from 01 March 1963 to 31 March 1965 (NODC Accession 9400163)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected from GAVESHANI and other platforms using zooplankton net casts in the TOGA Area - Atlantic and Indian Ocean. Data were collected...

  4. Zooplankton data from zooplankton net casts and other instruments in the Delaware Bay and North Atlantic Ocean as part of the Ocean Continental Shelf (OCS - Mid Atlantic) project, 03 November 1976 - 18 November 1977 (NODC Accession 7800340)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts and other instruments in the Delaware Bay and North Atlantic Ocean from November 3, 1976 to November 18,...

  5. Migration Theories

    Science.gov (United States)

    Crida, Aurélien

    2015-08-01

    The great variety of the architectures of the extra-solar planetary systems has revealed the fundamental role played by planetary migration: the interactions between the planets and the gaseous disk in which they form leads to a modification of their orbits. Here, I will review the basic processes and the most recent results in this area.Planets up to ~50 Earth masses are prone to so-called type I migration.I will describe the processes at play, namely the Lindblad and corotation torques, and explain how the total torque depends on the planet mass and the local disk structure. Application to realistic disks shows one or two sweet spot(s) for outward migration of planets roughly between 5 and 30 Earth masses around the snowline ; this is confirmed by dedicated 3D numerical simulations. This has strong consequences on the formation of hot Super-Earths or mini-Neptunes.For smaller mass planets, it has been recently proposed that the heating of the neighboring gas by the luminous planet can lead to a positive torque, hence promoting outward migration. On the other hand, if the planet is not a heat source, a cold finger appears, whose resulting torque is negative. Applications of these two recent results should be discussed.Giant planets open gaps in the proto-planetary disk, and then are supposedly subject to type II migration, following the viscous accretion of the disk. This standard picture has been questioned recently, as gas appears to drift through the gap. Although the gap opening process is well understood in 2D for a planet on a fixed orbit, recent results on 3D simulations or migrating planets make the picture more accurate.Our ever better understanding of planet-disk interactions is of crucial importance as the statistics on extra solar systems keep growing and the results of these interactions are now imaged.

  6. Zooplankton data collected from THOMAS G. THOMPSON in Arabian Sea; 18 September 1994 to 27 December 1995 (NODC Accession 9800077)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts in Arabian Sea from THOMAS G. THOMPSON. Data were collected from 18 September 1994 to 27 December 1995...

  7. A three-dimensional biophysical model of Karenia brevis dynamics on the west Florida shelf: A look at physical transport and potential zooplankton grazing controls

    Science.gov (United States)

    Milroy, Scott P.; Dieterle, Dwight A.; He, Ruoying; Kirkpatrick, Gary J.; Lester, Kristen M.; Steidinger, Karen A.; Vargo, Gabriel A.; Walsh, John J.; Weisberg, Robert H.

    2008-01-01

    The development of accurate predictive models of toxic dinoflagellate blooms is of great ecological importance, particularly in regions that are most susceptible to their detrimental effects. This is especially true along the west Florida shelf (WFS) and coast, where episodic bloom events of the toxic dinoflagellate Karenia brevis often wreak havoc on the valuable commercial fisheries and tourism industries of west Florida. In an effort to explain the dynamics at work within the maintenance and termination phases of a red tide, a simple three-dimensional coupled biophysical model was used in the analysis of the October 1999 red tide offshore Sarasota, Florida. Results of the numerical experiments indicate that: (1) measured and modeled flowfields were capable of transporting the observed offshore inoculum of K. brevis to within 16 km of the coastal boundary; (2) background concentrations (1000 cells L -1) of K. brevis could grow to a red tide of over 2×10 6 cells L -1 in little more than a month, assuming an estuarine initiation site with negligible offshore advection, no grazing losses, negligible competition from other phytoplankton groups, and no nutrient limitation; (3) maximal grazing pressure could not prevent the initiation of a red tide or cause its termination, assuming no other losses to algal biomass and a zooplankton community ingestion rate similar to that of Acartia tonsa; and (4) the light-cued ascent behavior of K. brevis served as an aggregational mechanism, concentrating K. brevis at the 55 ?E m -2 s -1 isolume when mean concentrations of K. brevis exceeded 100,000 cells L -1. Further improvements in model fidelity will be accomplished by the future inclusion of phytoplankton competitors, disparate nutrient availability and limitation schemes, a more realistic rendering of the spectral light field and the attendant effects of photo-inhibition and compensation, and a mixed community of vertically-migrating proto- and metazoan grazers. These model refinements are currently under development and shall be used to aid progress toward an operational model of red tide forecasting along the WFS.

  8. Influence de la luminosité nocturne et de la turbidité sur le comportement vertical de migration de la civelle d'anguille (Anguilla anguilla L. dans l'estuaire de l'Adour

    Directory of Open Access Journals (Sweden)

    DE CASAMAJOR M. N.

    1999-07-01

    Compte tenu des observations effectuées, le schéma migratoire vertical de l'espèce peut être modélisé de la manière suivante : l'interaction entre la luminosité nocturne et la turbidité influence les déplacements de civelles dans la colonne d'eau en relation avec leur comportement lucifuge. Plus la lumière nocturne qui pénètre dans la colonne d'eau est importante et plus les civelles migrent en profondeur.

  9. Spatial and temporal variation in mercury bioaccumulation by zooplankton in Lake Champlain (North America)

    International Nuclear Information System (INIS)

    Trophic transfer of Hg across lakes within a region has been related to multiple environmental factors, but the nature of these relationships across distinct basins within individual large lakes is unknown. We investigated Hg bioaccumulation in zooplankton in basins of differing trophic status in Lake Champlain (Vermont, USA) to determine the strongest predictors of Hg bioaccumulation. Zooplankton were sampled in Malletts Bay (oligotrophic) and Missisquoi Bay (eutrophic) in 2005–2008. Zooplankton in the eutrophic basin had lower concentrations of total Hg and MeHg than those in the oligotrophic basin in all years but 2007, when no bloom occurred in Missisquoi. In addition, Hg concentrations in seston and small zooplankton, sampled during 2009 at 12 sites spanning the lake, decreased with increasing phytoplankton and zooplankton biomass. Thus, Hg bioaccumulation in zooplankton across basins in Lake Champlain is related to trophic status, as observed previously in multiple lake studies. - Highlights: ? Lake Champlain zooplankton Hg was lower in the eutrophic than the oligotrophic basin. ? Algal blooms in years present biodiluted Hg in plankton. ? Lake-wide spatial patterns of Hg in plankton decreased with increasing biomass. ? Lake-wide Hg bioaccumulation patterns are consistent with multiple lake studies. - Large spatiotemporal variations in MeHg bioaccumulation in zooplankton within a single large lake were linked to spatial variation in trophic status across basins and to inter-annual variation in algal density.

  10. PHYTOPLANKTON AND ZOOPLANKTON SEASONAL DYNAMICS IN A SUBTROPICAL ESTUARY: IMPORTANCE OF CYANOBACTERIA

    Science.gov (United States)

    Murrell, Michael C. and Emile M. Lores. 2004. Phytoplankton and Zooplankton Seasonal Dynamics in a Subtropical Estuary: Importance of Cyanobacteria. J. Plankton Res. 26(3):371-382. (ERL,GB 1190). A seasonal study of phytoplankton and zooplankton was conducted from 1999-20...

  11. 210Po uptake by zooplankton during a one year cycle in relation to trophic conditions in Monaco Bay

    International Nuclear Information System (INIS)

    Former evidence showed that in oligotrophic waters in French Polynesia there is an inverse correlation between zooplankton biomass and zooplankton 210Po concentration. To study the same phenomenon in a more seasonal environment, monthly samples of zooplankton, water, fecal pellets, and particulate organic matter were obtained in Monaco monthly and analyzed for 210Po content

  12. Micro-zooplankton and its abundance relative to the larger zooplankton and other seston components, 08 February 1967 to 27 February 1967 (NODC Accession 0000916)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Micro-zooplankton populations in the upper 100 m were sampled from 5 marine environments in the northeast Pacific Ocean extending from slope waters off San Diego to...

  13. Zooplankton community analysis in the Changjiang River estuary by single-gene-targeted metagenomics

    Science.gov (United States)

    Cheng, Fangping; Wang, Minxiao; Li, Chaolun; Sun, Song

    2014-07-01

    DNA barcoding provides accurate identification of zooplankton species through all life stages. Single-gene-targeted metagenomic analysis based on DNA barcode databases can facilitate longterm monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity>96%) or genus level (similaritymetagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.

  14. Zooplankton Variation of Murat River (Elaz??- within the borders Palu district

    Directory of Open Access Journals (Sweden)

    Hilal Bulut

    2014-01-01

    Full Text Available Zooplankton of Murat River was examined from monthly taken samples between June 2011 and May 2012. As a result of research were identified total 33 species, 25 of them belong to Rotifera, 6 belong to Cladocera, 2 belong to Copepoda. Zooplanktonik species were comprised as 75.76% Rotifera 18.18% Cladocera and 6.06% Copepoda species. There was marked decrease in at the zooplankton species diversity in winter months. There was sharp increase at the zooplankton species diversity in spring and in summer months. Especially in spring month’s zooplankton were recorded in highest species and numbers individual. The most species were determined in April (nine species. At least species were determined January (four species. pH, dissolved oxygen, water temperature were measured of the study area. The study has got an importance as to be the first research on zooplankton in this area.

  15. The effect of salinity levels on the structure of zooplankton communities

    Directory of Open Access Journals (Sweden)

    Paturej Ewa

    2015-01-01

    Full Text Available The objective of this study was to determine the qualitative and quantitative structure of zooplankton communities in the Vistula Lagoon and to establish whether zooplankton abundance and biodiversity are affected by salinity levels. Samples for biological analyses were collected in the summer (June-September of 2007-2011 at eleven sampling sites. Statistical analysis revealed a significant correlation between salinity levels and the number of species (r= -0.2020, abundance (r= 0.1967 and biomass (r= 0.3139 of zooplankton. No significant correlations were found between salinity and the biodiversity of zooplankton. The results of the study suggest that salinity affects the abundance and structure, but not the diversity of zooplankton communities in the Vistula Lagoon.

  16. Neuronal Migration Disorders

    Science.gov (United States)

    NINDS Neuronal Migration Disorders Information Page Table of Contents (click to jump to sections) What is Neuronal Migration Disorders? Is there ... being done? Clinical Trials Organizations What is Neuronal Migration Disorders? Neuronal migration disorders (NMDs) are a group ...

  17. Neustonic microplastic and zooplankton in the North Western Mediterranean Sea

    OpenAIRE

    Collignon, Amandine; Hecq, Jean-Henri; Galgani, François; Voisin, Pierre; Collard, France; Goffart, Anne

    2012-01-01

    Neustonic microplastic and zooplankton abundance was determined in the North Western Mediterranean Sea during a summer cruise between July 9th and August 6th 2010, with a break between July 22th and 25th due to a strong wind event. Ninety percent of the 40 stations contained microplastic particles (size 0.3-5 mm) of various compositions: e.g., filaments, polystyrene, thin plastic films. An average concentration of 0.116 particles/m² was observed. The highest abundances (> 0.36 particles/m...

  18. Hydroacoustic estimation of zooplankton biomass at two shoal complexes in the Apostle Islands Region of Lake Superior

    Science.gov (United States)

    Holbrook, B.V.; Hrabik, T.R.; Branstrator, D.K.; Yule, D.L.; Stockwell, J.D.

    2006-01-01

    Hydroacoustics can be used to assess zooplankton populations, however, backscatter must be scaled to be biologically meaningful. In this study, we used a general model to correlate site-specific hydroacoustic backscatter with zooplankton dry weight biomass estimated from net tows. The relationship between zooplankton dry weight and backscatter was significant (p biomass, we used geostatistics to analyze the mean and variance, and ordinary kriging to create spatial zooplankton distribution maps. The mean zooplankton dry weight biomass estimates from plankton net tows and hydroacoustics were not significantly different (p = 0.19) but the hydroacoustic data had a significantly lower coefficient of variation (p biomass that were not discernable from the overall means.

  19. Zooplankton size and distribution within mesoscale structures in the Mozambique Channel: A comparative approach using the TAPS acoustic profiler, a multiple net sampler and ZooScan image analysis

    Science.gov (United States)

    Lebourges-Dhaussy, A.; Huggett, J.; Ockhuis, S.; Roudaut, G.; Josse, E.; Verheye, H.

    2014-02-01

    Two surveys were conducted in the Mozambique Channel in November 2009 and April/May 2010 to study the influence of mesoscale eddies on the zooplanktonic component of the ecosystem. Three complementary methods were used to sample zooplankton: (1) hydro-acoustics with a TAPS™ multi-frequency zooplankton profiler; (2) in situ biological sampling using a Multinet with samples processed via the classical settled biovolume technique; (3) ZooScan image analysis which determines biovolume, size and taxonomic composition. This approach presented an ideal opportunity to compare the results of these different methods which highlighted a large overlap in their detectable size range. Each method favoured a particular size fraction of the population, i.e. TAPS for the microzooplankton (3 mm ESR). In the case of the 2009 cruise, a well-established cyclone-anticyclone dipole was sampled, with results clearly indicating a higher concentration of zooplankton in the cyclonic eddy compared to the anticyclonic counterpart. The TAPS also detected high surface (0-22 m) concentrations of what appeared to be microzooplankton or marine snow in the cyclone. In 2010, the eddy field was less defined and more spatially variable compared to that in 2009. Two cyclonic and anticyclonic features were sampled during the cruise, each with different life histories and levels of stability. Results were inconsistent compared to those of 2009 and dependent on the size component of the population, with both cyclonic and anticyclonic features capable of having higher planktonic biomass. Differences in species composition between these mesoscale features were not too different and mainly a matter of relative biovolume. Less well formed eddy fields, particularly in the mid-Mozambique Channel, therefore appear to result in indistinct vertical and horizontal zooplankton distribution patterns.

  20. International Migration and Remittances

    Directory of Open Access Journals (Sweden)

    Dattatray Sitaram Bagade

    2012-08-01

    Full Text Available Human migration is a physical movement by human beings from one geographical areato another geographical area. Migration is internal as well as external. At theinternational level, no universally accepted definition for “Migrant” exists. The UniteNations defines “migration as an individual who has resided in a foreign country formore than one year irrespective of the causes, voluntary or involuntary, and the means,regular or irregular, used migrate”. Key terms of migrations is documented migration,economic migration, irregular migration, skilled migration, temporary workersmigration, internally displaced persons (IDP migration, refugee, stateless person, etc. .

  1. Short-term variation in zooplankton community from Daya Bay with outbreaks of Penilia avirostris

    Directory of Open Access Journals (Sweden)

    Kaizhi Li

    2014-06-01

    Full Text Available The zooplankton community structure in bays fluctuates as a result of anthropogenic activities in such waters. We focused on the short-term variability of a zooplankton community and compared its differences at the outflow of a nuclear power plant (ONPP, in a marine cage-culture area (MCCA and in unpolluted waters (UW in the south-west part of Daya Bay from 28 April to 1 June 2001. Environmental factors and zooplankton abundance differed significantly among stations at ONPP, MCCA and UW: high temperatures and a high zooplankton abundance occurred at ONPP, while a high chlorophyll a concentration and a low zooplankton abundance prevailed in MCCA. Statistical analysis revealed that the zooplankton diversity and abundance could be reduced by the activity of the marine cage-culture in a short time. Penilia avirostris made up an important component of the zooplankton in the study area, its abundance ranging widely from 16 to 7267 indiv. m-3 from April to June and peaking at the ONPP outflow. The outbreak of P. avirostris probably resulted from the combined effects of favourable water temperature, food concentration and its parthenogenetic behaviour.

  2. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    Science.gov (United States)

    Le Quéré, C.; Buitenhuis, E. T.; Moriarty, R.; Alvain, S.; Aumont, O.; Bopp, L.; Chollet, S.; Enright, C.; Franklin, D. J.; Geider, R. J.; Harrison, S. P.; Hirst, A.; Larsen, S.; Legendre, L.; Platt, T.; Prentice, I. C.; Rivkin, R. B.; Sathyendranath, S.; Stephens, N.; Vogt, M.; Sailley, S.; Vallina, S. M.

    2015-07-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs); six types of phytoplankton, three types of zooplankton, and heterotrophic bacteria. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing zooplankton, and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean High Nutrient Low Chlorophyll (HNLC) region during summer. When model simulations do not represent crustacean macrozooplankton grazing, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there was no iron deposition from dust. When model simulations included the developments of the zooplankton component, the simulation of phytoplankton biomass improved and the high chlorophyll summer bias in the Southern Ocean HNLC region largely disappeared. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  3. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    Directory of Open Access Journals (Sweden)

    C. Le Quéré

    2015-07-01

    Full Text Available Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs; six types of phytoplankton, three types of zooplankton, and heterotrophic bacteria. We improved the representation of zooplankton dynamics in our model through (a the explicit inclusion of large, slow-growing zooplankton, and (b the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean High Nutrient Low Chlorophyll (HNLC region during summer. When model simulations do not represent crustacean macrozooplankton grazing, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there was no iron deposition from dust. When model simulations included the developments of the zooplankton component, the simulation of phytoplankton biomass improved and the high chlorophyll summer bias in the Southern Ocean HNLC region largely disappeared. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  4. Spatial distribution of zooplankton in the intertidal marsh creeks of the Yangtze River Estuary, China

    Science.gov (United States)

    Zhou, Shuchan; Jin, Binsong; Guo, Li; Qin, Haiming; Chu, Tianjiang; Wu, Jihua

    2009-11-01

    Zooplankton are important grazers of primary production within intertidal marshes and are the optimal prey of higher trophic consumers; however, the patterns of their spatial distribution in marsh creeks are rarely reported. The zooplankton in the intertidal creeks with different salinities at Dongtan marshes of the Yangtze River Estuary was surveyed. The mean zooplankton densities in the intertidal creeks were 53,638 ind. m -3 in April and 132,916 ind. m -3 in July, respectively, which were as high as in the near-shore subtidal waters of the Yangtze River Estuary. This high abundance implied the important roles of zooplankton in the matter flux between marshes and near-shore waters through complex intertidal creek systems. Zooplankton total densities changed significantly from northern to southern creeks. ANOSIM and CCA analyses revealed that the zooplankton community structure were significantly different among the northern, eastern and southern creeks, and between two sampling seasons. Salinity accounted for most of the spatial variation of zooplankton community, whereas water temperature, chlorophyll a concentration, and pH were the main reasons of the temporal variation observed. Copepods were the most abundant zooplankton group. A total of 24 copepod species, belonging to 15 families and 20 genera, were recorded. Planktonic copepods preferred the northern and eastern creeks, with higher densities in July than in April, while benthic copepods predominated only in the northern creeks in April. Since the role of benthic and planktonic copepods may differ in transporting nutrients in the intertidal creeks, it is suggested that the variations in their distribution may influence the ecological functions of zooplankton in the estuarine matter fluxes both spatially and temporally.

  5. Biochemical composition and calorific value of zooplankton from the coastal waters of South Andaman

    Directory of Open Access Journals (Sweden)

    M. Arun Kumar

    2013-09-01

    Full Text Available Estimation of biochemical composition of zooplankton is important in understanding their metabolism, nutritive value and energy transfer which are relevant to the marine ecosystem. Zooplankton biomass and their biochemical composition were estimated from the coastal waters of South Andaman during October 2011 to September 2012. The dry weight biomass and chlorophyll a discerned a positive correlation (p is less than 0.05; one-way ANOVA in two stations. Protein formed the major fraction of the organic constituents. Seasonal variation in the protein content of zooplankton was observed. Carbohydrate was the minor component and ranged from 1.1-12.2% ( Mean= 3.4+-1.1 in terms of dry weight. Neither lipid nor carbohydrate appeared to be significant source of energy for these organisms. Caloric value obtained in this study ranged from 1.35 to 2.72 kcal/g dry weight ( Mean=1.8+-0.2. Relatively higher values were attributed to the dominance of calanoid copepods in the zooplankton population almost throughout the year. Zooplankton did not show an extensive lipid storage suggesting that protein may serve as metabolic reserve. It is therefore evident that zooplankton can be utilized as nutritional live feed for the cultivable species of fish and prawn in aquaculture farms. The variations in biochemical composition of zooplankton are influenced by species composition and feeding activities of zooplankton, which is in accordance with the previous studies. This study is the first report on Biochemical Composition and Calorific Value of Zooplankton from the coastal waters of Port Blair, South Andaman.

  6. Changes in the abundance and composition of zooplankton from the ports of Mumbai, India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaonkar, C; Venkat, K.; Anil, A.C

    . 3.2 Zooplankton abundance Station wise variations in the abundance of zooplankton during the 3 different sampling periods (Nov 01, Apr 02 and Oct 02) are shown in Fig. 2 a, b and c. The zooplankton abundance peaked at station 5 (556515 100m -3... arabiensis. The variation in copepod abundance is presented in Fig. 7. The maximum observed abundance was found during Nov 01 at station 5 (Fig. 7a) followed by Oct 02 at station 4 (Fig. 7c) and Apr 02 at station 2 (Fig. 7b). 4 Discussion Results of our...

  7. VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Buesseler, K.O.; Trull, T.W.; Steinberg, D.K.; Silver, M.W.; Siegel, D.A.; Saitoh, S.-I.; Lamborg, C.H.; Lam, P.J.; Karl, D.M.; Jiao, N.Z.; Honda, M.C.; Elskens, M.; Dehairs, F.; Brown, S.L.; Boyd, P.W.; Bishop, J.K.B.; Bidigare, R.R.

    2008-06-10

    The VERtical Transport In the Global Ocean (VERTIGO) study examined particle sources and fluxes through the ocean's 'twilight zone' (defined here as depths below the euphotic zone to 1000 m). Interdisciplinary process studies were conducted at contrasting sites off Hawaii (ALOHA) and in the NW Pacific (K2) during 3 week occupations in 2004 and 2005, respectively. We examine in this overview paper the contrasting physical, chemical and biological settings and how these conditions impact the source characteristics of the sinking material and the transport efficiency through the twilight zone. A major finding in VERTIGO is the considerably lower transfer efficiency (T{sub eff}) of particulate organic carbon (POC), POC flux 500/150 m, at ALOHA (20%) vs. K2 (50%). This efficiency is higher in the diatom-dominated setting at K2 where silica-rich particles dominate the flux at the end of a diatom bloom, and where zooplankton and their pellets are larger. At K2, the drawdown of macronutrients is used to assess export and suggests that shallow remineralization above our 150 m trap is significant, especially for N relative to Si. We explore here also surface export ratios (POC flux/primary production) and possible reasons why this ratio is higher at K2, especially during the first trap deployment. When we compare the 500 m fluxes to deep moored traps, both sites lose about half of the sinking POC by >4000 m, but this comparison is limited in that fluxes at depth may have both a local and distant component. Certainly, the greatest difference in particle flux attenuation is in the mesopelagic, and we highlight other VERTIGO papers that provide a more detailed examination of the particle sources, flux and processes that attenuate the flux of sinking particles. Ultimately, we contend that at least three types of processes need to be considered: heterotrophic degradation of sinking particles, zooplankton migration and surface feeding, and lateral sources of suspended and sinking materials. We have evidence that all of these processes impacted the net attenuation of particle flux vs. depth measured in VERTIGO and would therefore need to be considered and quantified in order to understand the magnitude and efficiency of the ocean's biological pump.

  8. VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

    Science.gov (United States)

    Buesseler, K. O.; Trull, T. W.; Steinberg, D. K.; Silver, M. W.; Siegel, D. A.; Saitoh, S.-I.; Lamborg, C. H.; Lam, P. J.; Karl, D. M.; Jiao, N. Z.; Honda, M. C.; Elskens, M.; Dehairs, F.; Brown, S. L.; Boyd, P. W.; Bishop, J. K. B.; Bidigare, R. R.

    2008-07-01

    The VERtical Transport In the Global Ocean (VERTIGO) study examined particle sources and fluxes through the ocean's "twilight zone" (defined here as depths below the euphotic zone to 1000 m). Interdisciplinary process studies were conducted at contrasting sites off Hawaii (ALOHA) and in the NW Pacific (K2) during 3-week occupations in 2004 and 2005, respectively. We examine in this overview paper the contrasting physical, chemical and biological settings and how these conditions impact the source characteristics of the sinking material and the transport efficiency through the twilight zone. A major finding in VERTIGO is the considerably lower transfer efficiency ( Teff) of particulate organic carbon (POC), POC flux 500/150 m, at ALOHA (20%) vs. K2 (50%). This efficiency is higher in the diatom-dominated setting at K2 where silica-rich particles dominate the flux at the end of a diatom bloom, and where zooplankton and their pellets are larger. At K2, the drawdown of macronutrients is used to assess export and suggests that shallow remineralization above our 150-m trap is significant, especially for N relative to Si. We explore here also surface export ratios (POC flux/primary production) and possible reasons why this ratio is higher at K2, especially during the first trap deployment. When we compare the 500-m fluxes to deep moored traps, both sites lose about half of the sinking POC by >4000 m, but this comparison is limited in that fluxes at depth may have both a local and distant component. Certainly, the greatest difference in particle flux attenuation is in the mesopelagic, and we highlight other VERTIGO papers that provide a more detailed examination of the particle sources, flux and processes that attenuate the flux of sinking particles. Ultimately, we contend that at least three types of processes need to be considered: heterotrophic degradation of sinking particles, zooplankton migration and surface feeding, and lateral sources of suspended and sinking materials. We have evidence that all of these processes impacted the net attenuation of particle flux vs. depth measured in VERTIGO and would therefore need to be considered and quantified in order to understand the magnitude and efficiency of the ocean's biological pump.

  9. Studies on the associates and parasites of zooplankton from southwest and southeast coasts of India

    Digital Repository Service at National Institute of Oceanography (India)

    Santhakumari, V.

    Associates and parasites of zooplankton from southwest and southeast coasts of India were studied. Among the epizoic forms two species of ciliates infesting copepods were new records from Indian waters. Eight species of suctorians were found epizoic...

  10. Zooplankton standing stock assessment and fishery resources in the indian seas

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Sarupria, J.S.; Bhargava, R.M.S.

    Based on data from 1864 samples collected over a period of 12 years (1976-88), an assessment of zooplankton standing stock (biomass), secondary production and potential fishery resources has been made. The areas studied included Arabian Sea, Bay...

  11. Elemental (C, H, N) composition of zooplankton from north Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Bhat, K.L.; Ansari, Z.A.; Parulekar, A.H.

    Zooplankton samples collected from north Arabian Sea during March 1992 were analysed for elemental (C,H,N) composition. Estimated carbon, hydrogen and nitrogen concentrations displayed variations among different groups but their ratios were nearly...

  12. Preliminary studies on the association between zooplankton and the stramenopilan fungi, Aplanochytrids

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, V.S.; Damare, S.R.; Ramanujam, P.; Meena, R.M.; Raghukumar, S.

    : [1] using fluorescently-labeled prey approach and [2] using internal transcribed spacerbased molecular probe and in situ hybridization approach. The aplanochytrid cells were detected in the guts as well as fecal pellets of the zooplankton, thus...

  13. Phytoplankton and zooplankton of some paddy-cum-prawn culture fields in and around Cochin

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishnan, T.C.; Devi, C.B.L.; Aravindakshan, P.N.; Nair, K.K.C.; Balasubramanian, T.; Kutty, M.K.

    The Phytoplankton and zooplankton from the paddy-cum-prawn culture fields from 4 areas in and around the Cochin backwaters were studied. Total Phytoplankton counts in the seasonal and perennial fields in all the areas showed good similarity...

  14. Biochemical composition and caloric potential of zooplankton from Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sreepada, R.A.; Rivonker, C.U.; Parulekar, A.H.

    Proximate composition and variations in protein, lipid, carbohydrate, ash and organic carbon in zooplankton from 42 stations in the Bay of Bengal are reported. Average percentages of moisture, protein, lipid, carbohydrate, ash and carbon were 85...

  15. EFFECTS OF DIFFERENT MIXING SCHEDULES ON PHYTOPLANKTON, ZOOPLANKTON AND NUTRIENTS IN MARINE MICROCOSMS

    Science.gov (United States)

    An experiment was carried out with different mixing schedules in marine microcosms. Continuous mixing resulted in higher chlorophyll concentrations, lower nutrient concentrations and lower zooplankton biomass than no mixing. No mixing caused water-column stratifications of chloro...

  16. Migration of birds

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers the migration of birds. Topics covered include why birds migrate, when birds migrate, speed, altitude, courses, distance, major flyways and...

  17. Spatial and temporal variation in mercury bioaccumulation by zooplankton in Lake Champlain (North America)

    OpenAIRE

    Chen, Celia; Kamman, Neil; Williams, Jason; Bugge, Deenie; Taylor, Vivien; Jackson, Brian; Miller, Eric

    2011-01-01

    Trophic transfer of Hg across lakes within a region has been related to multiple environmental factors, but the nature of these relationships across distinct basins within individual large lakes is unknown. We investigated Hg bioaccumulation in zooplankton in basins of differing trophic status in Lake Champlain (Vermont, USA) to determine the strongest predictors of Hg bioaccumulation. Zooplankton were sampled in Malletts Bay (oligotrophic) and Missisquoi Bay (eutrophic) in 2005–2008. Zooplan...

  18. Zooplankton of Two Drinking Water Reservoirs in Central Anatolia: Composition and Seasonal Cycle

    OpenAIRE

    DEM?R, Nilsun

    2005-01-01

    Comparative studies were performed on the zooplankton composition and some physical and chemical properties of the Kurtbo?az? and Çaml?dere reservoirs. Zooplankton abundance, conductivity, organic matter, hardness and orthophosphate concentrations were lower and Secchi depth was higher in Çaml?dere than in Kurtbo?az? (P < 0.01). Rotifera species such as Polyarthra dolichoptera, Keratella quadrata, Asplanchna priodonta and Ascomorpha saltans showed peaks, particularly in spring, summer and ...

  19. Evaluation of sound extinction and echo interference in densely aggregated zooplankton

    OpenAIRE

    Natalia Gorska

    2000-01-01

    The investigation of sound extinction and echo interference is important as regards the accurate assessment of the abundance of densely aggregated zooplankton. To study these effects,the analytical model describing sound backscattering by an aggregation of isotropic scatterers (Rytov et al. 1978, Sun & Gimenez 1992) has been extended to the case of densely aggregated elongated zooplankton. The evaluation of the effects in the case of a dense krill aggregation demonstrates that they can b...

  20. The Impact of Fish Predation and Cyanobacteria on Zooplankton Size Structure in 96 Subtropical Lakes

    OpenAIRE

    Zhang, Jing; Ping XIE; Tao, Min; Guo, Longgen; Chen, Jun; Li, Li; XueZhen Zhang,; Zhang, Lu

    2013-01-01

    Zooplankton are relatively small in size in the subtropical regions. This characteristic has been attributed to intense predation pressure, high nutrient loading and cyanobacterial biomass. To provide further information on the effect of predation and cyanobacteria on zooplankton size structure, we analyzed data from 96 shallow aquaculture lakes along the Yangtze River. Contrary to former studies, both principal components analysis and multiple regression analysis showed that the mean zooplan...

  1. Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs

    OpenAIRE

    Persson, Jonas

    2007-01-01

    Poor food quality can have large negative effects on zooplankton growth and this can also affect food web interactions. The main aims of this thesis were to study the importance of different food quality aspects in Daphnia, to identify potentially important differences among zooplankton taxa, and to put food quality research into a natural context by identifying the importance of food quality and quantity in lakes of different nutrient content. In the first experiment, the RNA:DNA ratio was p...

  2. Zooplankton and diatoms of temporary and permanent freshwater pans in the Mpumalanga Highveld region, South Africa

    OpenAIRE

    Riato, Luisa; Van Ginkel, Carin; Taylor, Jonathan C.

    2014-01-01

    This paper provides a description of the zooplankton and epiphytic diatom communities of permanent and temporary freshwater pans in the Mpumalanga Highveld region of South Africa. Few studies have investigated the biota of pans in this area, which is seriously threatened by mining and agricultural development. Nineteen pan sites within a 20 km radius covering a wide range of water chemistries were sampled once for zooplankton, epiphytic diatoms and water physico-chemical data in 2009. Collect...

  3. A multivariate approach to environmental-zooplankton relationships in Maldonado Bay (Uruguay)

    OpenAIRE

    Ana Milstein

    1986-01-01

    Environment-zooplankton relationships were analysed in Maldonado Bay (Uruguay), an estuarine area between the River Plate and the Atlantic Ocean. This was done through Principal Component Analysis. Most of the environment variability is accounted for, primarily, by the outflow of the River Plate and the inflow of coastal waters which change through the annual cycle, and in the second place by surface water conditions. On the other hand, most of the zooplankton variability is accounted for by ...

  4. Impact of the fungicide carbendazim in freshwater microcosms. II. Zooplankton, primary producers and final conclusions

    OpenAIRE

    P. J. Brink; Hattink, J.; Bransen, F.; Donk, E., van; Brock, T.C.M.

    2000-01-01

    Effects of chronic application of the fungicide Derosal(R) (active ingredient carbendazim) were studied in indoor macrophyte-dominated freshwater microcosms. The concentrations (0, 3.3, 33, 100, 330 and 1000 microg/l) were kept at a constant level for 4 weeks. This paper is the second of a series of two; it describes the effects on zooplankton and primary producers and presents an overall discussion. The zooplankton community was negatively affected by the three highest treatment levels (NOEC...

  5. Do zooplankton contribute to an ultraviolet clear-water phase in lakes?

    OpenAIRE

    Williamson, C. E.; Lange, H.J., de; Leech, D.M.

    2007-01-01

    Seasonal increases in the ultraviolet (UV) transparency of the surface waters of an oligotrophic lake in Pennsylvania suggest that clear-water phase (CWP) events similar to those previously observed for visible light also exist for the potentially damaging UV wavelengths. Seasonal increases in zooplankton grazers indicate that they play a role in these changes in UV that is similar to the role that zooplankton play in CWP events involving longer-wavelength visible, or photosynthetically activ...

  6. Accumulation of petroleum hydrocarbons in zooplankton of Banyas coastal waters (Syria)

    International Nuclear Information System (INIS)

    We present in this paper the distribution of petroleum hydrocarbons in seawater and their levels in zooplanktonic samples. Sampling operation was carried our between August 1995 and November 1996 in the coastal area of Banyas city (Eastern Mediterranean). Petroleum hydrocarbons concentrations were: ranged between non detectable values and 16.4 pill in seawater, and between non detectable values and 4304 ?/g dry weight in zooplanktonic samples

  7. Migration trends in Europe

    OpenAIRE

    Wanner, Philippe ( Laboratoire de démographie et d'études familiales, Université de Genève, Switzerland )

    2002-01-01

    In order to grasp the complexity of migration trends in Europe it is important, given the limitations of the available statistics, to look at the wider issue, breaking it down into four separate elements: 1. the migration flows affecting Council of Europe member states in recent decades, distinguishing between migration between member states and migration flows with other parts of the world; 2. the reasons for migration, with particular reference to illegal migration or asylum; 3. the socio-d...

  8. Effect of removal of free-floating macrophytes on zooplankton habitat in shallow wetland

    Directory of Open Access Journals (Sweden)

    Choi Jong-Yun

    2014-01-01

    Full Text Available Submerged macrophytes improve the structural heterogeneity of microhabitats in aquatic ecosystems, often providing an important habitat for zooplankton. However, excessive development of free-floating macrophytes on the water surface can reduce the biomass of submerged macrophytes and result in a relatively simple habitat structure. We hypothesized that controlling the development of free-floating macrophytes would result in a more complex habitat structure by promoting the development of submerged macrophytes. After applying three experimental treatments (NR, no removal; IR, intermediate removal; CR, complete removal of free-floating macrophytes, we found that CR of free-floating macrophytes improved the growth and development of submerged macrophytes and supported a large zooplankton assemblage. However, the largest zooplankton assemblage (in terms of abundance and diversity was recorded after the IR treatment. Although submerged macrophytes were abundant in the CR treatment, the number, abundance, and density of zooplankton species were much lower than those in the IR treatment. Preferential selection of different macrophyte types by zooplankton presumably led to variation in plant utilization of niches, and the simultaneous presence of different macrophyte life forms created a complex microhabitat structure that induced high species diversity and zooplankton density.

  9. Incorporation of nitrogen from N2 fixation into amino acids of zooplankton

    DEFF Research Database (Denmark)

    Loick-Wilde, Natalie; Dutz, Jörg

    2012-01-01

    Eurytemora affinis (Copepoda) were fed 15N-labeled Rhodomonas salina (Cryptophyta) or 15N-labeled Nodularia spumigena (Cyanobacteria) in excess under controlled laboratory conditions. Zooplankton collected from the Baltic Sea were fed natural phytoplankton amended with 15N-labeled N. spumigena. We quantified the direct incorporation of 15N tracer from N2-fixing N. spumigena (diazotroph nitrogen) and ammonium-utilizing R. salina into the amino acid nitrogen (AA-N) of zooplankton using complementary gas chromatography– combustion–isotope ratio mass spectrometry, gas chromatography–mass spectrometry, and elemental analysis– isotope ratio mass spectrometry approaches. Specific and mass-specific TN and AA-N incorporation rates of the 15N tracers were calculated for zooplankton. Highest incorporation of 15N was found in field zooplankton relying on N. spumigena and in E. affinis relying on R. salina. Lowest incorporation was found in E. affinis relying on N. spumigena. Decreasing specific and mass-specific rates during field experiments possibly were due to food shortage, whereas decreasing rates in E. affinis grazing on R. salina were more likely due to satiation. Specific and mass-specific rates were consistently low in E. affinis when exposed to N. spumigena, suggesting that these animals were reluctant to feed on N. spumigena. Essential isoleucine received most of the diazotroph nitrogen in field zooplankton, while nonessential amino acids received most 15N tracer in E. affinis. N. spumigena was clearly an important amino acid nitrogen source for Baltic Sea zooplankton

  10. Responses of phyto- and zooplankton communities to Prymnesium polylepis (Prymnesiales) bloom in the Baltic Sea.

    Science.gov (United States)

    Gorokhova, Elena; Hajdu, Susanna; Larsson, Ulf

    2014-01-01

    A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007-spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypotheses, we analyzed inter-annual variability in phytoplankton and zooplankton dynamics as well as growth indices (RNA:DNA ratio) in dominant zooplankton in relation to the Prymnesium abundance and biomass. Contrary to the hypothesized relationships, no measurable negative responses to P. polylepis were observed for either the total phytoplankton stocks or the zooplankton community. The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008. Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA:DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton. Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce. PMID:25393031

  11. Zooplankton Responses In A Tropical System With Environmental Stress

    Directory of Open Access Journals (Sweden)

    Nelson Javier Aranguren Riaño

    2014-03-01

    Full Text Available Processes of environmental transformation that currently occur in the climatic change context generate changes in ecosystems and biological communities. ¿How populations respond to these stressors? ¿what effects could occur on taxonomic and ecological diversity? The taxonomic composition and structure of the zooplankton was analyzed with relationship to environmental changes in a tropical water reservoir located at 6º02`18``N and 73º29`16`` W. During four months, samples were taken weekly covering stations of low, medium, and high precipitation. A high degree of temporal variability was established, it associated with a short hydraulic retention time estimated at 8 days.  Nine species were collected, of which Keratella tropica tropica and Thermocyclops decipiens were the two most abundant and constant species. Found values of H’ diversity and S richness were considered low, corresponding to a little mature community associated with a fluctuating physical environment and supported by high variation coefficients of electrical conductivity and Sechhi disk transparency. Drastic variations on the system volume in short time lapses generate important changes in the physical expression of system with a direct effect on composition and structure of the zooplankton. In general, the response model of the zooplankton in the reservoir according to the statement by the intermediate disturbance hypothesis.  RESPUESTAS DEL ZOOPLANCTON EN UN SISTEMA TROPICAL CON ALTA TENSIÓN AMBIENTAL Los procesos de transformación ambiental que se dan en la actualidad, en un marco de cambio climático, generan modificaciones en los ecosistemas y comunidades biológicas, ¿Cómo responden las poblaciones a estos factores de tensión? ¿Qué efectos se darían sobre la diversidad taxonómica y ecológica? Se analizó la variación de la composición taxonómica y estructura del zooplancton en función de los cambios ambientales en un reservorio tropical ubicado a 6º02`18``N y 73º29`16`` O.  Semanalmente se realizaron muestreos en la zona limnética del sistema durante cuatro meses que abarcaron los periodos seco, de transición y de alta precipitación. Se estableció un  alto grado de variabilidad temporal asociada al poco tiempo de retención hidráulica estimado en 8 días. Se registraron 9 especies, entre ellas Keratella tropica tropica y Thermocyclops decipiens  que fueron las más abundantes y constantes. Los valores de diversidad H´ y riqueza S hallados se consideran bajos, lo que corresponde a una comunidad poco madura vinculada a un ambiente físico fluctuante, evidenciado en los elevados coeficientes de variación de la conductividad eléctrica y la transparencia Secchi. La fluctuación del volumen del sistema en lapsos cortos de tiempo, genera cambios significativos en la expresión física del sistema con efecto directo sobre la composición y estructura del zooplancton.  En general el modelo de respuesta del zooplancton en este reservorio, se ajusta a los supuestos de la hipótesis de disturbio intermedio. 

  12. Measurement of vertical integration

    Energy Technology Data Exchange (ETDEWEB)

    Maddigan, R.J.

    1981-08-01

    An index of vertical integration is constructed as a tool to examine how the average level of vertical integration has changed over time. The hypothesis that if vertical integration can lower costs or reduce risks, more firms will integrate vertically is subjected to an empirical test using the Vertical Industry Connection index. A randem sample of firms is selected from the COMPUSAT data base. The results support the contention that vertical integration has increased in contrast with Laffer's findings. 17 references, 10 figures, 3 tables.

  13. Zooplankton of an urban coastal lagoon: composition and association with environmental factors and summer fish kill

    Scientific Electronic Library Online (English)

    Leonardo C. e, Souza; Christina W. C., Branco; Patrícia, Domingos; Sérgio L. C., Bonecker.

    2011-06-01

    Full Text Available Zooplankton may be regarded as a sensitive tool for monitoring environmental variations in coastal lagoons due to their ability to immediately react to changes in the water column trophic features and salinity levels. As a coastal lagoon with a broad history of anthropic influence, Rodrigo de Freita [...] s Lagoon (Rio de Janeiro, Brazil) is widely used for water sports and artisanal fishing. The present study aimed to expand the knowledge base about zooplankton in the Rodrigo de Freitas Lagoon by assessing the composition and time-spatial distribution of the major zooplankton groups. Samples were collected fortnightly from at four distinct sampling points August 2001 to July 2002. At each point, salinity, temperature, dissolved oxygen and water transparency were measured. During the study period, the lagoon behaved as an spatially homogeneous environment in what regards the abiotic variables. However, all these variables showed significant differences along the time, mainly related to seasonality (air temperature and rainy and dry periods). The zooplankton community showed low taxonomic richness, with the predominance of species commonly found in coastal lagoons, especially with mesohaline conditions, as well as those found in estuaries. An interesting fact was the rise in zooplankton abundance at all sampling points right after a fish kill event. Such increase was caused mainly by the Brachionus plicatilis O.F. Müller 1786 species. Thus, the zooplankton community was affected by physical and chemical factors, mainly by the dissolved oxygen decline event and variations in the influx of seawater into the lagoon. In addition, phytoplankton availability and fish predation pressure were suggested as important regulating factors of the zooplankton community.

  14. Zooplankton of an urban coastal lagoon: composition and association with environmental factors and summer fish kill

    Directory of Open Access Journals (Sweden)

    Leonardo C. e Souza

    2011-06-01

    Full Text Available Zooplankton may be regarded as a sensitive tool for monitoring environmental variations in coastal lagoons due to their ability to immediately react to changes in the water column trophic features and salinity levels. As a coastal lagoon with a broad history of anthropic influence, Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil is widely used for water sports and artisanal fishing. The present study aimed to expand the knowledge base about zooplankton in the Rodrigo de Freitas Lagoon by assessing the composition and time-spatial distribution of the major zooplankton groups. Samples were collected fortnightly from at four distinct sampling points August 2001 to July 2002. At each point, salinity, temperature, dissolved oxygen and water transparency were measured. During the study period, the lagoon behaved as an spatially homogeneous environment in what regards the abiotic variables. However, all these variables showed significant differences along the time, mainly related to seasonality (air temperature and rainy and dry periods. The zooplankton community showed low taxonomic richness, with the predominance of species commonly found in coastal lagoons, especially with mesohaline conditions, as well as those found in estuaries. An interesting fact was the rise in zooplankton abundance at all sampling points right after a fish kill event. Such increase was caused mainly by the Brachionus plicatilis O.F. Müller 1786 species. Thus, the zooplankton community was affected by physical and chemical factors, mainly by the dissolved oxygen decline event and variations in the influx of seawater into the lagoon. In addition, phytoplankton availability and fish predation pressure were suggested as important regulating factors of the zooplankton community.

  15. Migration and trade

    OpenAIRE

    Egger, Peter H.; Ehrlich, Maximilian von; Nelson, Douglas R.

    2011-01-01

    Theoretical and empirical research in economics suggests that bilateral migration triggers bilateral trade through a number of channels. This paper assesses the functional form of the impact of migration on trade flows in a quasi-experimental setting. We provide evidence that the relationship is not log-linear. In particular, at small levels of migration (stocks) the elasticity of trade to migration is quite high, and it declines to zero at about 4,000 immigrants. If migration stocks exceed s...

  16. International Migration and Remittances

    OpenAIRE

    Dattatray Sitaram Bagade

    2012-01-01

    Human migration is a physical movement by human beings from one geographical areato another geographical area. Migration is internal as well as external. At theinternational level, no universally accepted definition for “Migrant” exists. The UniteNations defines “migration as an individual who has resided in a foreign country formore than one year irrespective of the causes, voluntary or involuntary, and the means,regular or irregular, used migrate”. Key terms of migrations is documented migr...

  17. Characterization of intermittency in zooplankton behaviour in turbulence.

    Science.gov (United States)

    Michalec, François-Gaël; Schmitt, François G; Souissi, Sami; Holzner, Markus

    2015-10-01

    We consider Lagrangian velocity differences of zooplankters swimming in still water and in turbulence. Using cumulants, we quantify the intermittency properties of their motion recorded using three-dimensional particle tracking velocimetry. Copepods swimming in still water display an intermittent behaviour characterized by a high probability of small velocity increments, and by stretched exponential tails. Low values arise from their steady cruising behaviour while heavy tails result from frequent relocation jumps. In turbulence, we show that at short time scales, the intermittency signature of active copepods clearly differs from that of the underlying flow, and reflects the frequent relocation jumps displayed by these small animals. Despite these differences, we show that copepods swimming in still and turbulent flow belong to the same intermittency class that can be modelled by a log-stable model with non-analytical cumulant generating function. Intermittency in swimming behaviour and relocation jumps may enable copepods to display oriented, collective motion under strong hydrodynamic conditions and thus, may contribute to the formation of zooplankton patches in energetic environments. PMID:26490249

  18. Zooplankton diversity across three Red Sea reefs using pyrosequencing

    KAUST Repository

    Pearman, John K.

    2014-07-30

    Coral reefs are considered among the most diverse ecosystems on Earth, yet little is known about the diversity of plankton in the surrounding water column. Moreover, few studies have utilized genomic methods to investigate zooplankton diversity in any habitat. This study investigated the diversity of taxa by sampling 45 stations around three reef systems in the central/southern Red Sea. The diversity of metazoan plankton was investigated by targeting the 18S rRNA gene and clustering OTUs at 97% sequence similarity. A total of 754 and 854 metazoan OTUs were observed in the data set for the 1380F and 1389F primer sets respectively. The phylum Arthropoda dominated both primer sets accounting for ~60% of reads followed by Cnidaria (~20%). Only about 20% of OTUs were shared between all three reef systems and the relation between geographic distance and Jaccard Similarity measures was not significant. Cluster analysis showed that there was no distinct split between reefs and stations from different reefs clustered together both for metazoans as a whole and for the phyla Arthropoda, Cnidaria and Chordata separately. This suggests that distance may not be a determining factor in the taxonomic composition of stations.

  19. Small zooplankton sensing their environment: feeding, mating, and predator avoidance

    Science.gov (United States)

    Nihongi, Ai

    2004-03-01

    Since zooplankton play a significant role at the base of the food web in aquatic environments, it is important to understand their feeding behaviors, mating behaviors, and predator avoidance. First, I will present the water flow regime of Daphnia. Using a high-speed video, I filmed how water with algae particles enters and leaves Daphnia, how the water flows within Daphnia and how the appendages of Daphnia work to produce the water flow. Second, I will discuss mate-searching behaviors of freshwater calanoid copepods and Daphnia. Male and female zooplankters have to encounter each other for successful mating in 3D environment. I have observed the behaviors of freshwater calanoid copepods from Lake Michigan. As a result, they showed different behaviors from other species studied. Likewise, I have observed differences in mate-searching behaviors of D. pulex and D. magna. Last, I will show the results of predator-prey interactions in D. pulex with kairomone, a chemical cue, from predatory fish using 3-D near infrared optical system. As experimental conditions, we used the following treatments: (a) no light/ no kairomone, (b) no light/ kairomone, (c) light/ no kairomone, and (d) light/ kairomone. While it appears that light and kairomone have an interactive effect on the swimming behaviors of Daphnia, light seems to be the most influential factor. The observed frequent spinning movements of D. pulex in a darkened tank with a predatory fish, fathead minnow (Pimephales promelas), were successful predator avoidance maneuvers.

  20. Fatty acid transformation in zooplankton: from seston to benthos

    DEFF Research Database (Denmark)

    Tiselius, Peter; Hansen, Benni Winding

    2012-01-01

    All organic matter, fatty acids (FA) in particular, is transformed in the pelagic plankton food web before reaching fishes or benthic organisms. Mesozooplankton (0.2 to 2 mm) is the main conduit for FA transfer, and FA profiles in sedimenting matter should therefore be significantly affected by its activity. To test this hypothesis, we sampled seston, zooplankton and sediment trap material for FA analysis during 5 campaigns spanning 4 seasons at a coastal site on the west coast of Sweden. Saturated (SAFAs) and monounsaturated (MUFAs) FAs dominated seston and trap material, while copepods contained 75 to 90% polyunsaturated FAs (PUFAs). Sedimentation of bulk particulate organic carbon did not vary significantly with season (coefficient of variation, CV = 33%), while pigment (CV = 49%) and in particular faecal pellet fluxes (CV = 100%) were highly variable as a result of copepod feeding activity. Copepod feeding, pellet production and egg production were all high after the spring bloom and in summer and autumn. Overall, 5 to 25% of the sedimenting FAs were affected by copepod feeding activities, and the supply of PUFAs to the benthos was significantly enhanced by copepod grazing activity. SAFAs and MUFAs were enriched by 5 to 10% in sediment traps, while the proportion of the most important PUFA, docosahexaenoic acid, was reduced by up to 15% in summer and autumn. In conclusion, the periods of significant input of PUFAs to the sediment coincide with the period of highest transformation by the mesozooplankton, which in the present study was summer and autumn.

  1. Zooplankton of Lake Orta after liming: an eleven years study

    Directory of Open Access Journals (Sweden)

    Andrea PASTERIS

    2001-02-01

    Full Text Available Lake Orta (N. Italy was severely polluted from 1927 by an effluent from a rayon factory, which discharged great amounts of ammonium nitrogen and copper into the lake. In the mid nineteen fifties, some plating factories also started dumping chromium and aluminum. As a result of ammonium oxidation, the lake became very acid and the concentration of metals in the waters reached very high values. Phytoplankton, zooplankton and fish disappeared suddenly from the lake which was by 1930 classified as “sterile”. Later on, about the fifties, a small population of Cyclops abyssorum re-colonised the lake together with some rotifers, in particular Hexarthra fennica. In mid eighties following the introduction of anti-pollution legislation, ammonium loads were greatly reduced and Daphnia obtusa was recorded. The lake waters however were still very acid, prompting the proposal of the Istituto Italiano di Idrobiologia to lime the lake with calcium carbonate to neutralise the excess acidity and reconstruct the alkaline reserve. This was done successfully from May 1989 to June 1990. pH values began to rise and in the same time the metal concentrations decreased, so that at present the lake waters are almost “normal”. In the meantime, due to the increased pH values, D. obtusa was replaced by D. longispina and, as toxic metal concentrations became lower, Megacyclops viridis, Bosmina longirostris, Diaphanosoma brachyurum, Keratella quadrata, Asplanchna priodonta. and other Brachionidae species appeared. Diaptomidae are still absent, except for some specimens of Arctodiaptomus wierzejskii.

  2. In different pressure an experimental study on migration of radon

    International Nuclear Information System (INIS)

    The migration study of Radon in the air is the foundation theory problems of radon measurement and protection. Basing on experiment, this paper uses the method of active carbon accumulated measuring radon to study the migration regularity of radon gas in different gas pressure. Through series experiments, following conclusions can be obtained: the migration velocity of radon in the air is related with the air pressure, with greater air pressure, the conveyance speed is faster. Especially at low-pressure state the downward migration is more apparent. Through the comparison of measurement results of radon in vertical direction and a horizontal direction, the migration ability of radon in the vertical height is far larger than that in the horizontal direction whatever the pressure is. The average speed of radon in different pressures cases are estimated as follows: the upward migration average speed under atmospheric environment is 1.02 × 10-6 m/s, the downward migration average speed is 2.08 × 10-6 m/s; The upward migration average speed under -0.06 MPa vacuum environment is 0 91 × 10-6 m/s, the downward migration average speed is 2.77 × 10-6 m/s. As is consistent with the practical measurement result. (authors)

  3. Zooplankton data collected from BUREVESTNIK and other platforms in White Sea; 28 October 1952 to 12 February 1958 (NODC Accession 9900004)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts in White Sea from BUREVESTNIK and other platforms. Data were collected from 28 October 1952 to 12...

  4. Zooplankton characterisation of Pampean saline shallow lakes, habitat of the Andean flamingoes

    Directory of Open Access Journals (Sweden)

    Yamila S. Battauz

    2013-10-01

    Full Text Available The lowland saline shallow lakes in the Pampa de las Lagunas (Argentina, constitute an important habitat for flamingoes Phoenicopterus chilensis Molina and Phoenicoparrus andinus (Philippii. Little is known about the zooplankton communities of these systems, and their relationships with the temporal and spatial distribution of flamingoes. Ten shallow lakes in the Pampean region were studied in 2009 and 2010 winters, and in 2010 summer in order to assess the abundance, size and biomass of zooplankton and the density of flamingoes populations. Zooplankton was represented by 28 species. Copepods and cladocerans were dominant when salinity was lower (winter and summer of 2010. Seasonal changes were recorded in composition and mean abundance of zooplankton. Significant differences were  observed in mean size of zooplankton showing a negative relationship with the abundance of P. chilensis, which can be interpreted as a consequence of the selective flamingoes zooplanktophagy feeding upon the largest members of this community. Other community parameters, such as abundance, biomass, diversity and composition, did not show an apparent direct relationship with the presence or abundance of flamingoes.

  5. Zooplankton Atlas of the Southern Ocean: The SCAR SO-CPR Survey (1991-2008)

    Science.gov (United States)

    McLeod, David J.; Hosie, Graham W.; Kitchener, John A.; Takahashi, Kunio T.; Hunt, Brian P. V.

    2010-08-01

    The SCAR Southern Ocean Continuous Plankton Recorder (SO-CPR) Survey produces one of the largest and most accessed zooplankton data sets in the world. These data serve as a reference for other Southern Ocean monitoring programmes such as those run by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the developing Southern Ocean Observing System (SOOS). It has been instrumental in providing baseline data on zooplankton composition, communities, and distribution patterns on the ocean basin scale. The SO-CPR Survey is publishing the first detailed geographical atlas of the near-surface Southern Ocean zooplankton. This atlas is based on 22,553 CPR samples collected from 1991 to 2008 from voyages operated by Australia, Japan, Germany, New Zealand, USA and Russia. The Atlas documents the distribution and abundance of the 50 most abundant zooplankton taxa amongst the 200+ taxa sampled. The maps are printed in alphabetical order of the genera within each taxon and nomenclature is based on the Register of Antarctic Marine Species (RAMS) developed by the SCAR Marine Biodiversity Information Network (SCAR-MarBIN). The SO-CPR Atlas will operate as a ready reference to researchers interested in the distribution of zooplankton in the Southern Ocean, for example knowing the distribution of grazers in relation to phytoplankton production or the availability of prey for higher predators.

  6. Local and regional factors influencing zooplankton communities in the connected Kasseb Reservoir, Tunisia

    Scientific Electronic Library Online (English)

    Ikbel, Sellami; Jannet, Elloumi; Asma, Hamza; Mohammed Alaoui, Mhamdi; Habib, Ayadi.

    2011-04-01

    Full Text Available Associations between zooplankton community structure and abiotic (temperature, dissolved oxygen, turbidity, nutriments) and biotic factors (chlorophyll a and phytoplankton community) were examined, in Kasseb Reservoir, northern Tunisia. Samples were taken bimonthly from July to December 2002 at 3 sa [...] mpling stations (deepest station: Station 1, Brik River: Station 2 and M'Zaz Stama River: Station 3). From our results it is evident that zooplankton exhibit seasonally and spatially heterogeneous distribution. The highest density of zooplankton was recorded in September at a depth of 5 m (10.8 × 10³ ind·?-1). At Station 1 cyclopoid copepods (65% of total abundance) were the most abundant group followed by Cladocera (21% of total abundance). At Station 2 (93% of total abundance) and Station 3 (98% of total abundance) cyclopoid copepods were numerically dominant throughout the study period. Canonical correspondence analysis (CCA) was used to estimate the influence of abiotic and biotic factors in structuring the zooplankton assemblage. Zooplankton abundance was negatively correlated with turbidity (r= -0.381, P

  7. Combined effect of predatory zooplankton and allelopathic aquatic macrophytes on algal suppression.

    Science.gov (United States)

    Zuo, Shengpeng; Wan, Kun; Ma, Sumin

    2015-01-01

    The present study evaluated the combined effects of four typical predatory zooplankton and allelopathic aquatic macrophytes on algal control in a microcosm system. It would determine the effects of diverse species and biological restoration on the growth of harmful water-bloom microalgae in great lakes polluted by excess nutrients. It was found that the mixtures of each zooplankton and the floating plant Nymphoides peltatum had stronger inhibitory effects on harmful water-bloom microalgae than the individual species in clean or eutrophic water bodies. In addition, a community of four zooplankton types had a synergistic effect on algal inhibition. Algal suppression by the zooplankton community was enhanced significantly when the macrophyte was co-cultured in the microcosm. Furthermore, Chlorella pyrenoidosa was more susceptible than Microcystis aeruginosa when exposed to grazing by zooplankton and the allelopathic potential of the macrophyte. Algal inhibition was also weaker in eutrophic conditions compared with the control. These findings indicate that diverse species may enhance algal inhibition. Therefore, it is necessary to restore biological diversity and rebuild an ecologically balanced food chain or web to facilitate the control of harmful algal blooms in eutrophic lakes. PMID:25409583

  8. Vertical axis wind turbines

    Science.gov (United States)

    Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  9. The possibilities of least-squares migration of internally scattered seismic energy

    KAUST Repository

    Aldawood, Ali

    2015-05-26

    Approximate images of the earth’s subsurface structures are usually obtained by migrating surface seismic data. Least-squares migration, under the single-scattering assumption, is used as an iterative linearized inversion scheme to suppress migration artifacts, deconvolve the source signature, mitigate the acquisition fingerprint, and enhance the spatial resolution of migrated images. The problem with least-squares migration of primaries, however, is that it may not be able to enhance events that are mainly illuminated by internal multiples, such as vertical and nearly vertical faults or salt flanks. To alleviate this problem, we adopted a linearized inversion framework to migrate internally scattered energy. We apply the least-squares migration of first-order internal multiples to image subsurface vertical fault planes. Tests on synthetic data demonstrated the ability of the proposed method to resolve vertical fault planes, which are poorly illuminated by the least-squares migration of primaries only. The proposed scheme is robust in the presence of white Gaussian observational noise and in the case of imaging the fault planes using inaccurate migration velocities. Our results suggested that the proposed least-squares imaging, under the double-scattering assumption, still retrieved the vertical fault planes when imaging the scattered data despite a slight defocusing of these events due to the presence of noise or velocity errors.

  10. Zooplankton community changes confound the biodilution theory of methylmercury accumulation in a recovering mercury-contaminated lake.

    Science.gov (United States)

    Todorova, Svetoslava; Driscoll, Charles T; Matthews, David A; Effler, Steven W

    2015-04-01

    In this study, the biodilution hypothesis of methylmercury (MeHg) accumulation was examined in a Hg-contaminated ecosystem that has undergone concurrent changes in nutrient loading and zooplankton community composition. Using a long-term record of 17 years (between 1980 and 2009), we demonstrate that zooplankton MeHg concentrations in Onondaga Lake, NY, are strongly driven by changes in the zooplankton community and body size. MeHg concentrations in zooplankton increased with an increase in body size and biomass. The highest concentrations of MeHg were observed under eutrophic and hypereutrophic conditions when large-bodied Daphnia species, Daphnia pulicaria and Daphnia galeata mendotae, were present. Bioconcentration rather than biodilution was governing the accumulation of MeHg in zooplankton without apparent growth dilution or zooplankton biomass dilution. Algal-bloom dilution controlled the variability in the MeHg concentration only under hypereutrophic conditions when Ceriodaphnia predominated the cladoceran population. Our study demonstrates that changes in zooplankton community composition confound the biodilution theory in Onondaga Lake and that the presence of large-bodied zooplankton species drives elevated MeHg concentrations. PMID:25741879

  11. Inter-annual variability of a zooplankton community: the importance of summer concentrated rainfall in a regulated river ecosystem

    Directory of Open Access Journals (Sweden)

    Jong-Yun Choi

    2011-03-01

    Full Text Available We monitored the zooplankton community dynamics of a regulated river system (the Nakdong River in South Korea,in an effort to characterize the relationship between basin rainfall quantity and changes in zooplankton communitystructure. The river studied herein has four multipurpose dams upstream and one estuarine barrage at the river mouth,resulting in intensive flow regulation. We hypothesized that flow regulation would effect zooplankton community structurechanges not only within the summer period of concentrated rainfall, but also during the subsequent seasons. Fieldmonitoring was conducted on a weekly basis (1999 to 2009 at the study site (27 km upstream from the estuary dam.The studied years were divided into two groups: rainy years with annual rainfall greater than total average annual rainfall,and dry years (years with lower than average annual rainfall. The zooplankton community data was also dividedinto two groups according to year and community structural characteristics. The summer density of zooplankton waslow during the summer concentrated rainfall period. In the autumn, zooplankton density was statistically related toriver flow (r2 = 0.30, P < 0.05, N = 11, which was affected by the summer concentrated rainfall (r2 = 0.31, P < 0.05, N = 11.Furthermore, autumn zooplankton density was positively related to that observed in the summer (r2 = 0.53, P < 0.05, N= 11. Therefore, it can be concluded that summer concentrated rainfall can affect the following seasons’ zooplanktondensities caused by dam flow control, and the potential growth rate of zooplankton

  12. Size-related response of zooplankton to hydroclimatic variability and water-quality in an organically polluted estuary of the Basque coast (Bay of Biscay)

    Science.gov (United States)

    Intxausti, Lander; Villate, Fernando; Uriarte, Ibon; Iriarte, Arantza; Ameztoy, Iban

    2012-06-01

    Seasonal, interannual and spatial variabilities were analysed for the > 100 ?m and > 200 ?m zooplankton assemblages in the estuary of Bilbao throughout 1997-2000, and related to hydroclimatic and water-quality factors. Seasonal and interannual patterns of abundance differed between assemblages, and only the abundance of the > 100 ?m zooplankton was correlated with temperature. The large-sized zooplankton decreased more drastically than the small-sized zooplankton with decreasing salinity, and showed highest correlations with dissolved oxygen and water transparency. Seasonal changes were the major variability mode of zooplankton composition in both assemblages. Interannual changes associated to phytoplankton biomass and temperature were more evident in the small-sized zooplankton, whilst spatial differences related to oxygen depletion were more evident in the large-sized zooplankton. This indicates that small zooplankton was more sensitive to climate-related factors, while large zooplankton was more sensitive to water quality. Small copepods, cirriped larvae, appendicularians and Noctiluca were the main taxa responsible for the interannual variations in the > 100 ?m assemblage. In the > 200 ?m assemblage, large copepods were the main zooplankton responsible for the spatial variability related to oxygen depletion. Cnidarians and cladocerans responded mainly to decreases in salinity, and polychaete larvae were found to be unaffected by the decrease in dissolved oxygen and salinity. Results suggest that size-related differential responses of zooplankton should be considered when zooplankton monitoring is performed to assess the effect of climate forcing and pollution in coastal and estuarine environments.

  13. Metal and proton toxicity to lake zooplankton: A chemical speciation based modelling approach

    International Nuclear Information System (INIS)

    The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. The fitted results give toxic potencies increasing in the order H+ TOX to relate combined toxic effects of protons and metal cations towards lake crustacean zooplankton. • The fitted results give toxic potencies increasing in the order H+ TOX model has been applied to field data for pelagic lake crustacean zooplankton. The fitted results give metal toxic potencies increasing in the order H+ < Al < Cu < Zn < Ni

  14. Zooplankton composition in five oxbow lakes from the Upper Juruá River, Acre State, Brazil

    Directory of Open Access Journals (Sweden)

    Maria José Alencar dos Santos

    2013-12-01

    Full Text Available This work was conducted in five oxbow lakes located between Cruzeiro do Sul and Rodrigues Alves counties (Acre State, Brazil, to provide additional information about the composition of zooplankton assemblages in the Upper Juruá River. Samples were collected from May 2009 to May 2010, and fixed with 4% formalina. The numeric density (ind.m -3 was obtained from subsequent sub-samples (1 mL. The study recorded 19 zooplankton families. Rotifers showed higher species richness (81 species, followed by cladocerans (3 species and various forms of copepods and other organisms. Higher zooplankton means of numeric density was found in Novo Lake, with rotifers (1879 ind.m -3, cladocerans (207 ind.m -3, copepods (870 ind.m -3 . Diversity and numeric density were similar to other Neotropical aquatic ecosystems.

  15. Food habits of Juvenile American Shad and dynamics of zooplankton in the lower Columbia River

    Science.gov (United States)

    Haskell, C.A.; Tiffan, K.F.; Rondorf, D.W.

    2006-01-01

    As many as 2.4 million adult American shad annually pass John Day Dam, Columbia River to spawn upriver, yet food web interactions of juvenile shad rearing in John Day Reservoir are unexplored. We collected zooplankton and conducted mid-water trawls in McNary (June-July) and John Day reservoirs (August-November) from 1994 through 1996 during the outmigration of subyearling American shad and Chinook salmon. Juvenile American shad were abundant and represented over 98% of the trawl catch in late summer. The five major taxa collected in zooplankton tows were Bosmina longirostris, Daphnia, cyclopoid cope-pods, rotifers, and calanoid copepods. We evaluated total crustacean zooplankton abundance and Daphnia biomass in relation to water temperature, flow, depth, diel period, and cross-sectional location using multiple regression. Differences in zooplankton abundance were largely due to differences in water temperature and flow. Spatial variation in total zooplankton abundance was observed in McNary Reservoir, but not in John Day Reservoir. Juvenile American shad generally fed on numerically abundant prey, despite being less preferred than larger bodied zooplankton. A decrease in cladoceran abundance and size in August coupled with large percentages of Daphnia in juvenile American shad stomachs indicated heavy planktivory. Smaller juvenile American shad primarily fed on Daphnia in August, but switched to more evasive copepods as the mean size of fish increased and Daphnia abundance declined. Because Daphnia are particularly important prey items for subyearling Chinook salmon in mainstem reservoirs in mid to late summer, alterations in the cladoceran food base is of concern for the management of outmigrating salmonids and other Columbia River fishes. ?? 2006 by the Northwest Scientific Association. All rights reserved.

  16. Stable isotope methods: The effect of gut contents on isotopic ratios of zooplankton

    Science.gov (United States)

    Hill, J. M.; McQuaid, C. D.

    2011-05-01

    In the past decade there has been an increased awareness of the potential for methodological bias resulting from multiple pre-analytical procedures in foodweb interpretations based on stable isotope techniques. In the case of small organisms, this includes the effect of gut contents on whole body signatures. Although gut contents may not reflect actual assimilation, their carbon and nitrogen values will be isotopically lighter than after the same material has been assimilated. The potential skewing of isotopic ratios in whole organism samples is especially important for aquatic environments as many studies involve trophic relationships among small zooplankton. This is particularly important in pelagic waters, where herbivorous zooplankton comprise small taxa. Hence this study investigated the effect of gut contents on the ?13C and ?15N ratios of three size classes of zooplankton (1.0-2.0, 2.0-4.0 and >4.0 mm) collected using bongo net tows in the tropical waters of the south-west Indian Ocean. Animals were collected at night, when they were likely to be feeding, sieved into size classes and separated into genera. We focused on Euphausia spp which dominated zooplankton biomass. Three treatment types were processed: bulk animals, bulk animals without guts and tail muscle from each size class at 10 bongo stations. The ?15N ratios were influenced by zooplankton size class, presumably reflecting ontogenetic changes in diet. ANOVA post hoc results and correlations in ?15N signatures among treatments suggest that gut contents may not affect overall nitrogen signatures of Euphausia spp., but that ?13C signatures may be significantly altered by their presence. Carbon interpretations however, were complicated by potential effects of variation in chitin, lipids and metabolism among tissues and the possibility of opportunistic omnivory. Consequently we advocate gut evacuation before sacrifice in euphausiids if specific tissue dissection is impractical and recommend caution when using isotopic ratios of whole body zooplankton for trophic interpretations.

  17. Zooplankton assemblages and biomass during a 4-period survey in a northern Mediterranean coastal lagoon.

    Science.gov (United States)

    Lam-Hoai, T; Rougier, C

    2001-01-01

    The authors proposed to examine zooplankton biomass at three stations inside (T and Z) and outside (M) a coastal lagoon of the north-western Mediterranean Sea. Station T represented the lagoon central area, and station Z was positioned in a shellfish farming sector, while the seaside station (M) served as a reference of marine environment. Analyses were designed to outline the net zooplankton assemblages (taxonomic structures and length distributions) in different environmental conditions, including the farming activity. A discriminant analysis of environmental variables determined that temperature, salinity and phytoplankton implied mainly in spatial pattern of the samples. An ordination of taxa biomasses showed two main factors which might contribute to the organisation of the zooplankton assemblages: the geographical position and the thermal period. The geographical position integrated the lagoon-sea water exchange under forcing parameters (habitat, tides and winds). The thermal period reflected both the populations development cycles and the environmental constraints (temperature, salinity, trophic resources). The resulting effects appeared in structured zooplankton assemblages in space and time. The number of 50 microns interval length classes and of taxa decreased from the seaside and the lagoon central area free of farming activity to the shallower farming zone. But the biomass-length distribution profiles did not closely follow such an expected opposition between opened and confined areas: more extended profiles were observed at station Z. Biomass dominant size classes concerned the range up to 300 microns. This size category appeared to collapse in terms of biomass from the seaside or central area of the lagoon towards the farming area, similarly to zooplankton global biomass fluctuations. Difference between biomass levels and between biomass structures suggested that net zooplankton partly acted as food competitors of macro-filtering organisms, and as preys for farming shellfish and associated epifauna. This impact mainly concerned microzooplankton populations. PMID:11257882

  18. Migration and revolution

    Directory of Open Access Journals (Sweden)

    Nando Sigona

    2012-06-01

    Full Text Available The Arab Spring has not radically transformed migration patterns in the Mediterranean, and the label ‘migration crisis’ does not do justice to the composite and stratified reality.

  19. Evaluation of sound extinction and echo interference in densely aggregated zooplankton

    Directory of Open Access Journals (Sweden)

    Natalia Gorska

    2000-09-01

    Full Text Available The investigation of sound extinction and echo interference is important as regards the accurate assessment of the abundance of densely aggregated zooplankton. To study these effects,the analytical model describing sound backscattering by an aggregation of isotropic scatterers (Rytov et al. 1978, Sun & Gimenez 1992 has been extended to the case of densely aggregated elongated zooplankton. The evaluation of the effects in the case of a dense krill aggregation demonstrates that they can be significant and should be taken into account.

  20. Potential Importance of Fish Predation and Zooplankton Grazing on Natural Populations of Freshwater Bacteria †

    OpenAIRE

    Riemann, Bo

    1985-01-01

    The rates of ingestion of natural bacterial assemblages by natural populations of zooplankton (>50 ?m in size) were measured during a 19-day period in eutrophic Frederiksborg Slotssø, Denmark, as well as in experimental enclosures (containing 5.3 m3 of lake water). The fish and nutrients of the enclosures were manipulated. In enclosures without fish, large increases in ingestion by zooplankton >140 ?m in size were found (up to 3 ?g of C liter?1 h?1), compared with values less than 0.3 ?g of C...

  1. Zooplankton of the waters adjacent to the C. P. Crane generating station. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Grant, G.C.; Womack, C.J.; Olney, J.E.

    1980-08-01

    Zooplankton population in the Gunpowder River and its tributaries were sampled monthly from July, 1979-March, 1980 in a continuation of similar studies begun in March, 1979. The objective of the study was to determine the effect of the present once-through cooling system of the Crane Power Plant. The principal effect of the C.P. Crane generating station on zooplankton of the area is a displacement of an original freshwater community through the pumping of cooling water from Seneca Creek to Saltpeter Creek.

  2. Irregular Migration of Egyptians

    OpenAIRE

    ROMAN, Howaida

    2008-01-01

    After defining irregular migration and tackling its different dimensions, the analytical note proposes to analyse the causes and dynamics of irregular migration in Egypt. It highlights furthermore the determinants of EU Policies in the realm of irregular migration, and Egypt’s policy-making approach towards irregular migrants. The conclusion emphasizes the necessity of forging coherent and effective policies on irregular migration in the context of a partnership between origin countries and d...

  3. Globalization, Migration and Development

    OpenAIRE

    George, Susan; Samuel, John

    2002-01-01

    EnglishMigration may become the most important branch of demography in the earlydecades of the new millennium in a rapidly globalizing world. This paper discusses the causes, costsand benefits of international migration to countries of the South and North, and key issues of commonconcern. International migration is as old as national boundaries, though its nature, volume,direction, causes and consequences have changed. The causes of migration are rooted in the rate ofpopulation growth and the...

  4. Vertical distribution and isotopic composition of living planktonic foraminifera in the western North Atlantic

    International Nuclear Information System (INIS)

    Thirteen species of planktonic foraminifera collected with vertically stratified zooplankton tows in the slope water, Gulf Stream cold core ring, and northern Sargasso Sea show significant differences in their vertical distributions in the upper 200 meters of these different hydrographic regimes. Gulf Stream cold core rings may be responsible for a southern displacement of the faunal boundary associated with the Gulf Stream when reconstructed from the deep-sea sediment record. Oxygen isotope analyses of seven species reveal that nonspinose species (algal symbiont-barren) apparently calcify in oxygen isotope equilibrium, whereas spinose species usually calcify out of oxygen isotope equilibrium by approximately -0.3 to -0.4 per mil in delta18O values. The isotope data indicate that foraminifera shells calcify in depth zones that are significantly narrower than the overall vertical distribution of a species would imply

  5. Signatures of currency vertices

    CERN Document Server

    Holme, Petter

    2008-01-01

    Many real-world networks have broad degree distributions. For some systems, this means that the functional significance of the vertices is also broadly distributed, in other cases the vertices are equally significant, but in different ways. One example of the latter case is metabolic networks, where the high-degree vertices -- the currency metabolites -- supply the molecular groups to the low-degree metabolites, and the latter are responsible for the higher-order biological function, of vital importance to the organism. In this paper, we propose a generalization of currency metabolites to currency vertices. We investigate the network structural characteristics of such systems, both in model networks and in some empirical systems. In addition to metabolic networks, we find that a network of music collaborations and a network of e-mail exchange could be described by a division of the vertices into currency vertices and others.

  6. On Marriage and Migration

    OpenAIRE

    Stark, Oded

    1988-01-01

    Marriage, migration and related phenomena such as marital stability, fertility and investment in human capital may be better explained by studying marriage and migration jointly. We thus proceed in this paper to explore the role of migration in obtaining joint labour-market and marriage-market equilibrium. This facilitates identification of several novel and testable hypotheses.

  7. Current status of zooplankton in reservoir R-3 of the 'Mayak' production association

    Energy Technology Data Exchange (ETDEWEB)

    Osipova, O.; Pryakhin, E. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation); Ivanov, I. [FSUE Mayak PA (Russian Federation)

    2014-07-01

    One of the commonly used objects for the study of human influence on aquatic ecosystems is zooplankton. Zooplankton community is a sensitive component of biota in reservoir which can change their functional parameters and species composition in response to exposure to different factors. The role of zooplankton in the transformation of energy and in the biotic cycling of the substance is very important. The study of the responses of this element in the water ecosystem with anthropogenic influences, including radioactive contamination, is an important task. The object of the study was the zooplankton in the reservoir R-3, Chelyabinsk region, Russia. R-3 is located in the buffer zone of the 'Mayak' PA and is the storage for low-level radioactive waste. In addition to the high content of radionuclides (the average specific activity of {sup 90}Sr in water was 2.8 kBq/l, {sup 137}Cs - 0.7 kBq/l), this reservoir is characterized by high values of dichromate oxidizability and phosphate contamination. Previously, the study of the zooplankton of this reservoir was conducted in 1952, regular observations were not organized. Assessment of the current status of the community, more than half a century residing in the conditions of radioactive and chemical contamination, seems highly interesting. Sampling was carried out in 2011-2012 at three stations: in the upper, middle, and near the dam of the reservoir by the method of weighted average of samples with bathometer. Analysis of samples showed that the zooplankton community consists of the following major groups: rotifers and cladocerans and copepods crustaceans. In total in R-3 27 species of zooplankton, including 19 species of rotifers, 3 species of copepod and 3 species of cladocerans, as well as two species of ciliates were discovered. Zooplankton abundance in 2011 was 9±9 million individuals/m{sup 3} (given the mean and standard deviation), in 2012 - 26.0±0.9 million individuals/m{sup 3}. The main contribution was that of rotifers: 88.5 % of the total number of zooplankton organisms in 2011 and 97.5 % - in 2012. In general, the studied community is characterized by a high degree of heterogeneity of the structure without overwhelming dominance of one species. When compared with data obtained in 1952 by team headed by A.N. Marey, it could be said that the crustacean species has almost completely disappeared from zooplankton community along with the increase in the total abundance of planktonic animals which is two or three orders of magnitude higher due to the development of rotifers. These changes are characteristic of eutrophication processes that obviously play an important role in shaping the modern image of the zooplankton community in the reservoir R-3. Further investigation is required to determine the stability of the changes and clarify the role of radiation and chemical factors in these processes. Document available in abstract form only. (authors)

  8. Current status of zooplankton in reservoir R-3 of the 'Mayak' production association

    International Nuclear Information System (INIS)

    One of the commonly used objects for the study of human influence on aquatic ecosystems is zooplankton. Zooplankton community is a sensitive component of biota in reservoir which can change their functional parameters and species composition in response to exposure to different factors. The role of zooplankton in the transformation of energy and in the biotic cycling of the substance is very important. The study of the responses of this element in the water ecosystem with anthropogenic influences, including radioactive contamination, is an important task. The object of the study was the zooplankton in the reservoir R-3, Chelyabinsk region, Russia. R-3 is located in the buffer zone of the 'Mayak' PA and is the storage for low-level radioactive waste. In addition to the high content of radionuclides (the average specific activity of 90Sr in water was 2.8 kBq/l, 137Cs - 0.7 kBq/l), this reservoir is characterized by high values of dichromate oxidizability and phosphate contamination. Previously, the study of the zooplankton of this reservoir was conducted in 1952, regular observations were not organized. Assessment of the current status of the community, more than half a century residing in the conditions of radioactive and chemical contamination, seems highly interesting. Sampling was carried out in 2011-2012 at three stations: in the upper, middle, and near the dam of the reservoir by the method of weighted average of samples with bathometer. Analysis of samples showed that the zooplankton community consists of the following major groups: rotifers and cladocerans and copepods crustaceans. In total in R-3 27 species of zooplankton, including 19 species of rotifers, 3 species of copepod and 3 species of cladocerans, as well as two species of ciliates were discovered. Zooplankton abundance in 2011 was 9±9 million individuals/m3 (given the mean and standard deviation), in 2012 - 26.0±0.9 million individuals/m3. The main contribution was that of rotifers: 88.5 % of the total number of zooplankton organisms in 2011 and 97.5 % - in 2012. In general, the studied community is characterized by a high degree of heterogeneity of the structure without overwhelming dominance of one species. When compared with data obtained in 1952 by team headed by A.N. Marey, it could be said that the crustacean species has almost completely disappeared from zooplankton community along with the increase in the total abundance of planktonic animals which is two or three orders of magnitude higher due to the development of rotifers. These changes are characteristic of eutrophication processes that obviously play an important role in shaping the modern image of the zooplankton community in the reservoir R-3. Further investigation is required to determine the stability of the changes and clarify the role of radiation and chemical factors in these processes. Document available in abstract form only. (authors)

  9. Vertical pump assembly

    International Nuclear Information System (INIS)

    The mounting is described of the drive assembly of a vertical pump for nuclear power plants in areas with seismic risk. The assembly is attached to the building floor using flexible and damping elements. The design allows producing seismically resistant pumps without major design changes in the existing types of vertical pumps. (E.S.). 1 fig

  10. Synthetic seismic monitoring using reverse-time migration and Kirchhoff migration for CO2 sequestration in Korea

    Science.gov (United States)

    Kim, W.; Kim, Y.; Min, D.; Oh, J.; Huh, C.; Kang, S.

    2012-12-01

    During last two decades, CO2 sequestration in the subsurface has been extensively studied and progressed as a direct tool to reduce CO2 emission. Commercial projects such as Sleipner, In Salah and Weyburn that inject more than one million tons of CO2 per year are operated actively as well as test projects such as Ketzin to study the behavior of CO2 and the monitoring techniques. Korea also began the CCS (CO2 capture and storage) project. One of the prospects for CO2 sequestration in Korea is the southwestern continental margin of Ulleung basin. To monitor the behavior of CO2 underground for the evaluation of stability and safety, several geophysical monitoring techniques should be applied. Among various geophysical monitoring techniques, seismic survey is considered as the most effective tool. To verify CO2 migration in the subsurface more effectively, seismic numerical simulation is an essential process. Furthermore, the efficiency of the seismic migration techniques should be investigated for various cases because numerical seismic simulation and migration test help us accurately interpret CO2 migration. In this study, we apply the reverse-time migration and Kirchhoff migration to synthetic seismic monitoring data generated for the simplified model based on the geological structures of Ulleung basin in Korea. Synthetic seismic monitoring data are generated for various cases of CO2 migration in the subsurface. From the seismic migration images, we can investigate CO2 diffusion patterns indirectly. From seismic monitoring simulation, it is noted that while the reverse-time migration generates clear subsurface images when subsurface structures are steeply dipping, Kirchhoff migration has an advantage in imaging horizontal-layered structures such as depositional sediments appearing in the continental shelf. The reverse-time migration and Kirchhoff migration present reliable subsurface images for the potential site characterized by stratigraphical traps. In case of vertical CO2 migration at injection point, the reverse time migration yields better images than Kirchhoff migration does. On the other hand, Kirchhoff migration images horizontal CO2 migration clearer than the reverse time migration does. From these results, we can conclude that the reverse-time migration and Kirchhoff migration can complement with each other to describe the behavior of CO2 in the subsurface. Acknowledgement This work was financially supported by the Brain Korea 21 project of Energy Systems Engineering, the "Development of Technology for CO2 Marine Geological Storage" program funded by the Ministry of Land, Transport and Maritime Affairs (MLTM) of Korea and the Korea CCS R&D Center (KCRC) grant funded by the Korea government (Ministry of Education, Science and Technology) (No. 2012-0008926).

  11. Zooplankton ecology in the Mandovi-Zuari estuarine system of Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Padmavati, G.; Goswami, S.C

    were influenced by the southwest monsoon. Salinity fluctuations were drastic (0.1 to 36.6 x 10 sup(-3)). This appeared to cause variations in plankton production and heterogeneity of various taxa. Zooplankton biomass and total numerical counts varied...

  12. Initial succession of zooplankton and zoobenthos assemblages in newly formed quarry Lake Medard (Sokolov, Czech Republic).

    Czech Academy of Sciences Publication Activity Database

    Kosík, M.; ?adková, Z.; P?ikryl, I.; Se?a, Jaromír; Pechar, L.; Pecharová, E.

    Aachen : IMWA, 2011 - (Rüde, T.; Freund, A.; Wolkersdorfer, C.), s. 517-522 ISBN 978-1-897009-47-5 Institutional research plan: CEZ:AV0Z60170517 Keywords : brown coal mine pit lake * zoobenthos * zooplankton * crustaceans * conductivity Subject RIV: EH - Ecology, Behaviour

  13. Relative abundance of resident versus oceanic zooplankton over an interisland reef

    International Nuclear Information System (INIS)

    Zooplankton were collected from various substrate types. Densities were determined and results indicated that demersal plankton were abundant on the Japtan reef flat. Behavioral mechanisms were exhibited by many organisms including swimming near the substrate or in the lees of coral heads. Demersal plankton may provide an important food source for nocturnally foraging fishes

  14. Trace metal dynamics in zooplankton from the Bay of Bengal during summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; DineshKumar, P.K.; Nair, M.; Muraleedharan, K.R.

    of the northeast coast, and lowest concentrations in the open ocean warm gyre regions. The average trace metal concentrations (mu g g su(-1)) in coastal zooplankton (Fe, 44894.1 + or – 12198.2; Co, 46.2 + or – 4.6; Ni, 62.8 + or – 6.5; Cu, 84.9 + or – 6.7; Zn, 7546...

  15. Zooplankton biomass and potential fishery resources of the EEZ of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    An assessment of zooplankton biomass, secondary production and potential fishery resources of the EEZ of India was made from the data collected during a period of 15 years from 1976 to 1991. The areas studied included the Arabian Sea, Bay of Bengal...

  16. Changes in fish production effectivity in eutrophic fishponds of zooplankton structure.

    Czech Academy of Sciences Publication Activity Database

    Potužák, J.; H?da, J.; Pechar, Libor

    2007-01-01

    Ro?. 15, - (2007), s. 201-210. ISSN 0967-6120 R&D Projects: GA MŽP(CZ) SM/640/18/03; GA MŽP(CZ) SL/1/6/04 Institutional research plan: CEZ:AV0Z60870520 Keywords : fishponds * zooplankton * eutrophication * fish management * primary production Subject RIV: GL - Fishing Impact factor: 0.828, year: 2007

  17. Richness of Phytoplankton and Zooplankton in Water Streams at Jobolarangan Forest

    Directory of Open Access Journals (Sweden)

    WIRYANTO

    2001-07-01

    Full Text Available Plankton is components of aquatic ecosystem. Phytoplankton play as primary producers, zooplankton play an important role in the higher order in the transfer of energy primary producers, the alga, to the higher order consumers such as aquatic insects, larval fish, and some adult fish. Streams of Jobolarangan forest may show phytoplankton and zooplankton that unique. The objectives of this research were to know diversity of phytoplankton and zooplankton and to determined their density. Plankton were sampled using 25-30 ?m mesh net, in three location of streams, i.e.: Parkiran (1773 m asl., Mrutu (1875 m asl., and Air Terjun (1600 m asl.. Samples were examined under light microscope for identification, and determined their density/L. Richness of phytoplankton in streams at Jobolarangan forest composed by family of Chlorophyceae, Euglenophyceae (Algae, and Bacillariophyceae. Zooplanktons that were found order of rotifer, cladoceras, and copepods. Allochtonous productivity, low nutrient level, low light level, and flowing water condition caused density of plankton/L in stream at Jobolarangan was low, i.e. 0,064 to 0,232.

  18. Pollution effect on specific composition and diversity of zooplankton in Syrian coastal waters

    International Nuclear Information System (INIS)

    The main objective of this study was to compare specific composition of zooplankton in relatively polluted water with that in water considered clean. Certain differences in specific composition and in number of species were found for the two types of water

  19. Correlations between zooplankton assemblages and environmental factors in the downtown rivers of Shanghai, China

    Science.gov (United States)

    Yu, Na; Li, Erchao; Feng, Dexiang; Xiao, Baicai; Wei, Chaoqun; Zhang, Meiling; Chen, Liqiao

    2014-11-01

    Most urban rivers play an important role in urban flood control and drainage in China, but pollution is fast becoming an issue of greater importance in water management. In this study, 63 zooplankton species were recorded in four downtown rivers in Shanghai between November 2007 and October 2008. Of these, 44 species belonged to the Rotifera, 13 to Cladocera, and six to Copepoda. The three most frequently occurring zooplankton ( Brachionus calyciflorus, Microcyclops leuckarti, and Asplanchna priodonta) accounted for 80.00%, 76.84%, and 53.68%, respectively. Rotifera were found to be dominant, comprising 86.26% of total zooplankton, while cladoceran and copepod abundance amounted to 5.08% and 8.67%, respectively. Water temperature, salinity, electrical conductivity, and total nitrogen were of the greatest significance in the occurrence of zooplankton. Two species ( Schmackeria forbesi and Lepadella ovalis) were notably more sensitive to environmental factors such as salinity and electrical conductivity than other species. The population size and community were inversely correlated with the increasing nutrient levels of the four rivers, suggesting that the water quality of the four rivers had been gradually recovering from a severe eutrophic state and that water conditions of the rivers had been gradually improved.

  20. Zooplankton Linkages between Rivers and Great Lakes: Case Study from the St. Louis River

    Science.gov (United States)

    In this case study, we characterized the spatial and seasonal distribution and abundance of zooplankton within the hydrologically complex drowned river mouth of the St. Louis River, the second largest tributary to Lake Superior and an important fish nursery. We hypothesize that z...

  1. Metal and proton toxicity to lake zooplankton: A chemical speciation based modelling approach.

    Czech Academy of Sciences Publication Activity Database

    Stockdale, A.; Tipping, E.; Lofts, S.; Fott, J.; Garmo, Ø.; Hruška, Jakub; Keller, B.; Löfgren, S.; Maberlyh, S.; Majer, V.; Nierzwicki-Bauer, S. A.; Persson, G.; Schartau, A.; Thackeray, S. J.; Valois, A.; Vrba, Jaroslav; Walseng, B.; Yan, N.

    2014-01-01

    Ro?. 186, MAR (2014), s. 115-125. ISSN 0269-7491 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA ?R GA206/07/1200 Institutional support: RVO:67179843 ; RVO:60077344 Keywords : chemical speciation * bioavailability * recovery * crustacean zooplankton * lakes Subject RIV: EH - Ecology, Behaviour Impact factor: 4.143, year: 2014

  2. DEGRADATION OF THE PERITROPHIC MEMBRANE OF FRESH-WATER ZOOPLANKTON FECAL PELLETS

    Science.gov (United States)

    Fecal pellets produced by Lake Michigan and Douglas Lake zooplankton in laboratory experiments were settled gently onto microscope slides in specially designed settling chambers. Permanent slides of settled pellets were made in triplicate 24, 48, 72, 96, 120, and 144 hours after ...

  3. Effects of acid and cadmium on improved zooplankton in a Canadian shield lake

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, S.G.

    1980-01-01

    The effects of plankton invertebrate populations of added acid and of cadmium were monitored in seven 1.5 x 10/sup 5/ L impoundments placed over sediments in a lake being artificially acidified. Two enclosures were acidified to pH 5 and pH 4 and immediate effects on the zooplankton community studied. 1, 3, 10, and 30 ..mu..g cadmium/L were added to each of four enclosures in 1977 and residual effects of 1-10 ..mu..g Cd/L on the zooplankton community studied in 1978. The system containing 30 ..mu..g Cd/L was acidified to pH 4 in 1978 and effects on the zooplankton monitored. The biomass of the control impoundment was dominated by Diaptomus minutus. In all but one manipulated system the average total biomass was lower than in the control. The zooplankton biomass of manipulated systems were dominated by Tropocyclops prasinus mexicanus, Bosmina longirostris or rotifers. 14 references, 6 figures, 3 tables.

  4. Heavy metals and zooplankton with special reference to Minamata (Japan) mercury pollution - A case study

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Hirota, R.

    mercury was discharged about 30 years ago is still contaminated. Concentrations of total Hg in zooplankton decreased with increasing distance from the point of incident. Total Hg varied in the range of 0.037 to 5.40 mu g g/1 (dry) whereas methyl mercury...

  5. Trace metal concentrations in marine zooplankton from the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; Balachandran, K.K.; Nair, M.; Joseph, T.

    Trace metal contents in zooplankton samples were estimated as a part of Marine Research-Living Resource Programme (MRLR) programme at 24 stations to establish the importance of these metals in the Bay of Bengal. The average concentration of Fe, Co...

  6. Seasonal composition and population density of zooplankton in Lake Timsah, Suez Canal, Egypt:

    Directory of Open Access Journals (Sweden)

    Mohsen M. El-Sherbiny

    2011-09-01

    Full Text Available Zooplankton composition and abundance were investigated seasonally at ten sites in Lake Timsah and the adjacent, connected western lagoon in relation to the physico-chemical conditions. A total of 42 taxa (including larval stages were identified, among them 21 species of copepods, 6 rotifers, 5 cladocerans, 1 chaetognath and 1 urochordate. Copepods represented the predominant component (77.7% of the total community, followed by rotifers, molluscs, cladocerans and (9.2, 4.7 and 3.9% respectively, while other groups collectively formed about 4.5% of the total zooplankton population. Summer was the most productive season with an average count of 40 864 individuals m-3. The dominant copepod species were Paracalanus crassirostris and Oithona nana representing 28.3 and 24.3% of the total zooplankton respectively. The total zooplankton count, including copepods, and its dominant species showed significant positive correlations with temperature, pH and total phytoplankton density. However, negative correlations were detected between densities of rotifers, and salinity and dissolved oxygen.

  7. Biochemical composition of zooplankton of Bombay High (oil platform) area in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, K.L.; Wagh, A.B.

    the major component (greater than 80%) of zooplankton throughout the year. Of the proximate principals, protein formed the major component. Overall mean values, calculated as percentages of dry weight were 16.65 protein, 4.33 carbohydrate, 2.51 lipid and 23...

  8. Field responses to zooplankton populations to temperature changes caused by reactor operations

    International Nuclear Information System (INIS)

    Field determinations of thermal tolerance limits for zooplankton have helped in the definition of experiments needed to evaluate the effects of reactor operations upon these animals. Currently, the rates of births and deaths for populations of Cladocera are being quantified in hyperthermal and nonhyperthermal areas of the reactor cooling reservoir, Par Pond

  9. Horizontal and vertical dynamics of zooplankton and larval fish communities during mid-summer in Disko Bay, West Greenland

    DEFF Research Database (Denmark)

    Munk, Peter; Nielsen, Torkel Gissel; Hansen, Benni Winding

    2015-01-01

    Disko Bay is a highly productive inlet at the border between high- and low-arctic sectors of west Greenland. The physical/chemical conditions in the bay have changed during recent decades, specifically during an inflow event in 1996–1997 that led to increased deep-water temperatures. To further understand the consequences of physical changes to the plankton community in the bay, we examine findings from a field study on mesozooplankton and fish larvae in the areas of Disko Bay and Disko Bank car...

  10. The Vertical Distribution of Zooplankton at Ocean Station "P" in June-July, 1971 (NODC Accession 7500631)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The report contains the data gathered at Ocean Station "P" in late June and early July of 1971 on the "SUBARCTIC-A" cruise of R/V YAQUINA. The data include: 1)...

  11. A model to resolve organochlorine pharmacokinetics in migrating humpback whales.

    Science.gov (United States)

    Cropp, Roger; Nash, Susan Bengtson; Hawker, Darryl

    2014-07-01

    Humpback whales are iconic mammals at the top of the Antarctic food chain. Their large reserves of lipid-rich tissues such as blubber predispose them to accumulation of lipophilic contaminants throughout their lifetime. Changes in the volume and distribution of lipids in humpback whales, particularly during migration, could play an important role in the pharmacokinetics of lipophilic contaminants such as the organochlorine pesticide hexachlorobenzene (HCB). Previous models have examined constant feeding and nonmigratory scenarios. In the present study, the authors develop a novel heuristic model to investigate HCB dynamics in a humpback whale and its environment by coupling an ecosystem nutrient-phytoplankton-zooplankton-detritus (NPZD) model, a dynamic energy budget (DEB) model, and a physiologically based pharmacokinetic (PBPK) model. The model takes into account the seasonal feeding pattern of whales, their energy requirements, and fluctuating contaminant burdens in the supporting plankton food chain. It is applied to a male whale from weaning to maturity, spanning 20 migration and feeding cycles. The model is initialized with environmental HCB burdens similar to those measured in the Southern Ocean and predicts blubber HCB concentrations consistent with empirical concentrations observed in a southern hemisphere population of male, migrating humpback whales. Results show for the first time some important details of the relationship between energy budgets and organochlorine pharmacokinetics. PMID:24733631

  12. Bridging the gap between marine biogeochemical and fisheries sciences; configuring the zooplankton link

    DEFF Research Database (Denmark)

    Mitra, Aditee; Castellani, Claudia

    2014-01-01

    Exploring climate and anthropogenic impacts on marine ecosystems requires an understanding of how trophic components interact. However, integrative end-to-end ecosystem studies (experimental and/or modelling) are rare. Experimental investigations often concentrate on a particular group or individual species within a trophic level, while tropho-dynamic field studies typically employ either a bottom-up approach concentrating on the phytoplankton community or a top-down approach concentrating on the fish community. Likewise the emphasis within modelling studies is usually placed upon phytoplankton- dominated biogeochemistry or on aspects of fisheries regulation. In consequence the roles of zooplankton communities (protists and metazoans) linking phytoplankton and fish communities are typically under-represented if not (especially in fisheries models) ignored. Where represented in ecosystem models, zooplankton are usually incorporated in an extremely simplistic fashion, using empirical descriptions merging various interacting physiological functions governing zooplankton growth and development, and thence ignoring physiological feedback mechanisms. Here we demonstrate, within a modelled plankton food-web system, how trophic dynamics are sensitive to small changes in parameter values describing zooplankton vital rates and thus the importance of using appropriate zooplankton descriptors. Through a comprehensive review, we reveal the mismatch between empirical understanding and modelling activities identifying important issues that warrant further experimental and modelling investigation. These include: food selectivity, kinetics of prey consumption and interactions with assimilation and growth, form of voided material, mortality rates at different age-stages relative to prior nutrient history. In particular there is a need for dynamic data series in which predator and prey of known nutrient history are studied interacting under varied pH and temperature regimes

  13. Ecological investigation of zooplankton abundance in the river Haraz, northeast Iran: Impact of environmental variables

    Directory of Open Access Journals (Sweden)

    Jafari Naser

    2011-01-01

    Full Text Available The influence of physicochemical properties of Haraz river on its zooplankton composition and abundance were investigated at three sites for one year between August 2009 and July 2010. The present study records for the first time the aspects of zooplankton diversity and composition in relation to the physicochemical environment of the Haraz river. Only three groups of zooplankton were found: Rotifera with eighteen genera; Cladocera with nine and Copepoda with six genera. Rotifera was the predominant group (64.89%, followed by Cladocera (19.62% and Copepoda (15.32%. Upstream, the abundance was 805 individuals/m3, while it varied from 922 to 1126 ind/m3 downstream. Alkaline pH and nutrients were the main environmental factors which affected zooplankton abundance in the river. Site variation in dominance, diversity, evenness and richness were calculated. The study revealed that the presence of certain species, such as Lepadella sp., Mesocyclops sp., Polyarthra sp. and Brachionus sp. is considered to be a biological indicator for eutrophication. The calculated Jack1 values of sites 1 to 3 were 7.624, 16.426 and 19.221, respectively. The Shannon-Wiever species diversity index (H’ values were also different for all the three sites viz., site 1 (1.992, site 2 (1.21 and site 3 (2.48. Simpson’s dominance index (H value was highest at site 1 (0.692, indicating maximum dominance, whereas at site 3 dominance was the lowest (0.227 and diversity was the highest. Overall, our results showed that changes in the water quality of the river Haraz have considerable effects on the composition of zooplankton assemblages that can potentially affect the functioning of these ecosystems.

  14. Bridging the gap between marine biogeochemical and fisheries sciences; configuring the zooplankton link

    Science.gov (United States)

    Mitra, Aditee; Castellani, Claudia; Gentleman, Wendy C.; Jónasdóttir, Sigrún H.; Flynn, Kevin J.; Bode, Antonio; Halsband, Claudia; Kuhn, Penelope; Licandro, Priscilla; Agersted, Mette D.; Calbet, Albert; Lindeque, Penelope K.; Koppelmann, Rolf; Møller, Eva F.; Gislason, Astthor; Nielsen, Torkel Gissel; St. John, Michael

    2014-12-01

    Exploring climate and anthropogenic impacts on marine ecosystems requires an understanding of how trophic components interact. However, integrative end-to-end ecosystem studies (experimental and/or modelling) are rare. Experimental investigations often concentrate on a particular group or individual species within a trophic level, while tropho-dynamic field studies typically employ either a bottom-up approach concentrating on the phytoplankton community or a top-down approach concentrating on the fish community. Likewise the emphasis within modelling studies is usually placed upon phytoplankton-dominated biogeochemistry or on aspects of fisheries regulation. In consequence the roles of zooplankton communities (protists and metazoans) linking phytoplankton and fish communities are typically under-represented if not (especially in fisheries models) ignored. Where represented in ecosystem models, zooplankton are usually incorporated in an extremely simplistic fashion, using empirical descriptions merging various interacting physiological functions governing zooplankton growth and development, and thence ignoring physiological feedback mechanisms. Here we demonstrate, within a modelled plankton food-web system, how trophic dynamics are sensitive to small changes in parameter values describing zooplankton vital rates and thus the importance of using appropriate zooplankton descriptors. Through a comprehensive review, we reveal the mismatch between empirical understanding and modelling activities identifying important issues that warrant further experimental and modelling investigation. These include: food selectivity, kinetics of prey consumption and interactions with assimilation and growth, form of voided material, mortality rates at different age-stages relative to prior nutrient history. In particular there is a need for dynamic data series in which predator and prey of known nutrient history are studied interacting under varied pH and temperature regimes.

  15. A global analysis of zooplankton in natural and artificial fresh waters

    Directory of Open Access Journals (Sweden)

    Faye L. Merrix-Jones

    2013-02-01

    Full Text Available Water-body size and location influence zooplankton diversity in freshwaters, but less is known about systematic variations in zooplankton community composition between natural and artificial waters on different continents. We used meta-analysis to assess how zooplankton in artificial water bodies across different biomes might differ from natural water bodies of similar size. Among 79 lakes, ponds and reservoirs (11 artificial and 68 natural, proximity to other water bodies apparently increased species richness in all lake types, probably reflecting dispersal. However, richness did not differ systematically between natural and artificial water bodies of comparable size. In contrast, community composition differed between artificial and natural waters after accounting for depth, productivity, longitude and conductivity, with models explaining up to 50% of the overall variance at genus level. Leptodiaptomus, Chydorus, Cyclops, Acanthocyclops, Skistodiaptomus, Epischura, Limnocalanus, Senecella, Heterocope, Arctodiaptomus and Aglaodiaptomus all occurred more frequently in natural waters, whilst Thermocyclops, Moina and Epischura occurred more frequently in artificial lakes. Rank-occurrence data revealed that Ceriodaphnia, Orthocyclops, Holopedium and Eucyclops were equitably distributed across water bodies of contrasting sizes, depths and climates. Other genera occurred under more specific conditions, typically where they had strong associations with natural lakes (e.g. Limnocalanus, Senecella, Heterocope, Arctodiaptomus and Aglaodiaptomus. These results are among the first to illustrate systematic differences in zooplankton composition between natural and artificial lakes at a global scale. Potential explanations require further evidence, but might include provision for niche specialists in natural lakes versus reduced heterogeneity, management or disturbance effects in artificial lakes; and effects of lake age, stability and habitat naturalness in natural lakes. While zooplankton communities in natural lakes are well studied globally, more extensive data are required from artificial lakes.

  16. Restoring lakes by using artificial plant beds: habitat selection of zooplankton in a clear and a turbid shallow lake

    DEFF Research Database (Denmark)

    Schou, Majbritt Overgård; Risholt, Casper; Lauridsen, Torben L.; Søndergaard, Martin; Grønkjær, Peter; Jacobsen, Lene; Berg, Søren; Skov, Christian; Brucet, Sandra; Jeppesen, Erik

    2009-01-01

    1. Return of large-bodied zooplankton populations is of key importance for creating a shift from a turbid to a clear-water state in shallow lakes after a nutrient loading reduction. In temperate lakes, recovery is promoted by submerged macrophytes which function as a daytime refuge for large zooplankton. However, recovery of macrophytes is often delayed and use of artificial plant beds (APB) has been suggested as a tool to enhance zooplankton refuges, thereby reinforcing the shift to a clear-wat...

  17. Feminization of migrations?

    Directory of Open Access Journals (Sweden)

    Morokvaši? Mirjana

    2010-01-01

    Full Text Available Women have always taken part in migrations, but their presence varied depending on their origins, on the labour market situation both in the areas of origin and in the target areas, as well as the migration policies in the immigration areas. Their presence was not always visible and did not attract as much scholarly and political attention as today. What happened, how can one explain such an interest lately, whereas only few years ago the subject was marginal, in the shadow of the "mainstream - malestream", i.e. migration as a phenomenon which focuses on geographic mobility of men, while women are not considered as equal protagonists, they either follow or remain at home. Could the so called "feminization" of migration explain the great and sudden interest for women and gender in migrations? This text critically examines the notion of "feminization" considered today as one of the main dimensions of global migration flows. Drawing on trends both globally and in specific countries, it shows that "feminization" is neither a new nor a sudden trend and entails variations depending on the origins, level of development and maturity of migration flows. In some groups men were primo-migrants and with a gradual feminization the flows reach a balanced sex ratio. There where women migrated first, or became numerically predominant, one observs the opposite trend: a "masculinization". Some authors rightly refer to "gender transition", the term which covers both trends. It is argued in the conclusion that the visibility and growing interest for women in migration and, more recently, for a gender perspective in migration, is not only due to the changing migration patterns and profile of migrants but also to the renewal of theoretical perspectives in migration and gender studies in a context that largely facilitated that renewal. The focus of our attention today on specific aspects of migration is triggered not only by genuine changes in migration trends, but it is also a result of a long process of visibilisation in the academic production on migration, women and gender. These trends may have existed earlier in the migration history but had remained in the shadow of categories defining, recording and analyzing migration.

  18. Migration and pollution

    OpenAIRE

    Jha, Raghbendra; Whalley, John

    2003-01-01

    We explore the links between migration of labour and location specific (urban) pollution, suggesting a sense in which pollution can be welfare improving. In a conventional Harris-Todaro model of urban-rural migration, individuals migrate so as to equate the expected urban wage (given a downward rigid real wage in the urban sector) to the real wage. Unemployment is endogenously determined. Interpreting unemployment as damage, urban pollution (damage denoted in units of labour) can also support...

  19. Migration within the Eurozone

    OpenAIRE

    Graversen, Mads Byskov

    2013-01-01

    As society ads more and more value to human capital, it is becoming increasingly important. Especially for regions which need migration to smooth their overall unemployment. This aspect of migration within the Eurozone is of vital importance as Dreyer & Schmid (2013) earlier concluded that the fiscal transfers are highly lacking. Therefore according to Mundell’s theory (1961), in order to correct this lacking aspect of the Eurozone, there should be a high internal migration to be an optimum c...

  20. Regime shifts in shallow lakes: the importance of seasonal fish migration

    DEFF Research Database (Denmark)

    Brönmark, Christer; Brodersen, Jakob

    2010-01-01

    Shallow eutrophic lakes commonly exist in two alternative stable states: a clear-water state and a turbid water state. A number of mechanisms, including both abiotic and biotic processes, buffer the respective states against changes, whereas other mechanisms likely drive transitions between states. Our earlier research shows that a large proportion of zooplanktivorous fish populations in shallow lakes undertake seasonal migrations where they leave the lake during winter and migrate back to the lake in spring. Based on our past research, we propose a number of scenarios of how feedback processes between the individual and ecosystem levels may affect stability of alternative stable states in shallow lakes when mediated by fish migration. Migration effects on shallow lakes result from processes at different scales, from the individual to the ecosystem. Our earlier research has shown that ecosystem properties, including piscivore abundance and zooplankton productivity, affect the individual state of zooplanktivorous fish, such as growth rate or condition. Individual state, in turn, affects the relative proportion and timing of migrating zooplanktivorous fish. This change, in turn, may stabilize states or cause runaway processes that eventually lead to state shifts. Consequently, such knowledge of processes coupled to seasonal migration of planktivorous fish should increase our understanding of shallow lake dynamics.

  1. Recent blooms of the dinoflagellate Ceratium in Albert Falls Dam (KZN): history, causes, spatial features and impacts on a reservoir ecosystem and its zooplankton

    Scientific Electronic Library Online (English)

    Rob C, Hart; Peter D, Wragg.

    2009-07-01

    Full Text Available A lake-wide bloom of the dinoflagellate Ceratium hirundinella, discovered in Albert Falls Dam in October 2006, exposed a significant ecological change indicative of reduced water quality in this historically mesotrophic reservoir. The spatial distribution of the bloom was examined synoptically in Oc [...] tober 2006 and January 2007; these surveys revealed generally higher dinoflagellate densities in inshore reaches of the lake, and especially in the discharge plume of the inflowing Mgeni River. Ceratium totally dominated the phytoplankton assemblage, accounting almost completely for coincident chlorophyll levels, which generally increased with depth to generate a 'deep' chlorophyll maximum. Vertical oxygen profiles during the bloom differed substantially from corresponding profiles during non-bloom conditions historically typical in this reservoir. Direct count data and ordination analysis using non-metric multidimensional scaling exposed marked changes in zooplankton community structure compared to seasonally congruent non-bloom conditions in other years. Changes included the effective replacement of Moina by Bosmina, substantial reductions in Daphnia and Ceriodaphnia, and smaller but definite increases in abundance especially of calanoid copepods, as well as cyclopoid copepods and of Chaoborus, although not all of these differences were apparent in both survey months. These compositional changes are attributable to intrinsic differences in feeding biology among taxa and their associated susceptibility to the altered food environment, which was commensurate with Ceratium's emergence. In addition, chydorid cladocerans appeared as a new (but spatially restricted) eutrophic bio-indicator component of the zooplankton, and the species diversity of cyclopoid copepods was enriched. The historical incidence of Ceratium in the lake since 1995 coincided with low NO3-N:TP values (used here as an N:P ratio proxy), particularly of inflow waters, and with broadly coincident values in the open lake. Ceratium was present but sparse in 1995, at average N:P ratios around 5.5. It disappeared in 1996 when the ratio increased radically to >10, and reappeared in 2004 after an erratic decline of the ratio to

  2. Regional Redistribution and Migration

    DEFF Research Database (Denmark)

    Manasse, Paolo; Schultz, Christian

    1999-01-01

    We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out to be equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to sub...

  3. Vertical distribution of natural radionuclides in soils

    Directory of Open Access Journals (Sweden)

    Lozano J. C.

    2012-04-01

    Full Text Available Low-level alpha spectrometry techniques using semiconductor detectors (PIPS and liquid scintillation counters (LKB Quantulus 1220™ were used in order to determine the activity concentration of 238U, 232Th, 234U, 230Th, 226Ra, and 210Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were selected with different levels of influence from the installation, in such a way that they had different levels of radioactive contamination. The vertical profiles in the soils (down to 40 cm depth were studied in order to evaluate the vertical distribution of the natural radionuclides. The possible contamination of subsurface waters depends strongly on vertical migration, and the transfer to plants (herbs, shrubs, and trees also will depend on the distribution of the radionuclides in the root zone. The study of the activity ratios between radionuclides belonging to the same series allowed us to assess the differing behaviour of the radionuclides involved. The vertical profiles for these radionuclides were different at each sampling point, showing the local impact of the installation. However, the profiles per point were similar for the long-lived radionuclides of the 238TJ series (238U, 234U, 230Th, and 226Ra. Also, a major disequilibrium was observed between 210Pb and 226Ra in the surface layer, due to 222Rn emanation and subsequent surface deposition of 210Pb.

  4. Vertical distribution of natural radionuclides in soils

    Science.gov (United States)

    Blanco Rodríguez, P.; Tomé, F. Vera; Lozano, J. C.

    2012-04-01

    Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation counters (LKB Quantulus 1220™) were used in order to determine the activity concentration of 238U, 232Th, 234U, 230Th, 226Ra, and 210Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were selected with different levels of influence from the installation, in such a way that they had different levels of radioactive contamination. The vertical profiles in the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. The possible contamination of subsurface waters depends strongly on vertical migration, and the transfer to plants (herbs, shrubs, and trees) also will depend on the distribution of the radionuclides in the root zone. The study of the activity ratios between radionuclides belonging to the same series allowed us to assess the differing behaviour of the radionuclides involved. The vertical profiles for these radionuclides were different at each sampling point, showing the local impact of the installation. However, the profiles per point were similar for the long-lived radionuclides of the 238TJ series (238U, 234U, 230Th, and 226Ra). Also, a major disequilibrium was observed between 210Pb and 226Ra in the surface layer, due to 222Rn emanation and subsequent surface deposition of 210Pb.

  5. Vertical surround parallax correction

    Science.gov (United States)

    Lipton, Lenny

    2007-02-01

    An improved technique for displaying stereoscopic moving images is described that makes for a more comfortable and enjoyable viewing experience by reducing the conflict of cues that occurs at the vertical edges of the screen surround when objects with negative parallax values are partially occluded. One such means for mitigating the vertical surround edge conflicts is given, in which the convergence of the camera fields is effectively altered to produce the zero parallax condition in the regions of the image immediately adjacent to the vertical edges of the screen surround. The transition is proportional to the proximity to the vertical edge and controlled proportionately. The net effect of this edge treatment is to allow for an increase in the projected image's parallax budget, thereby heightening the overall depth effect.

  6. Hybrid vertical cavity laser

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2010-01-01

    A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.

  7. Asymmetric vertical integration

    OpenAIRE

    Buehler, Stefan; Schmutzler, Armin

    2005-01-01

    We examine vertical backward integration in a reduced-form model of successive oligopolies. Our key findings are: (i) There may be asymmetric equilibria where some firms integrate and others remain separated, even if firms are symmetric initially; (ii) Efficient firms are more likely to integrate vertically. As a result, integrated firms also tend to have a large market share. The driving force behind these findings are demand/mark-up complementarities in the product market. We also identify ...

  8. Radon migration in the soils of the Irno Valley (Southern Italy) inferred from radioactive disequilibrium

    OpenAIRE

    P. Gasparini; C. Sabbarese; Martino, S.

    1995-01-01

    Radon migration along vertical profiles in the soils of Irno River alluvial Valley (Southern Italy) was studied using radioactive disequilibrium between 226 Ra and 210 Pb. Fractional Radon loss, migration length, diffusion and emanation coefficient and Radon flux density were determined. Our results are in agreement with a migra- tion model by simple diffusion. The migration parameters are within typical values, except the Radon flux density, which is about one order of magnitude higher than ...

  9. Factors influencing zooplankton size structure at contrasting temperatures in coastal shallow lakes: Implications for effects of climate change

    OpenAIRE

    Brucet Balmaña, Sandra; Boix Masafret, Dani; Quintana Pou, Xavier; Jensen, Elisabeth; Nathansen, Louise W.; Trochine, Carolina; Meerhoff, Mariana; Gascón Garcia, Stéphanie; Jeppesen, Erik

    2010-01-01

    We assessed the importance of temperature, salinity, and predation for the size structure of zooplankton and provided insight into the future ecological structure and function of shallow lakes in a warmer climate. Artificial plants were introduced in eight comparable coastal shallow brackish lakes located at two contrasting temperatures: cold-temperate and Mediterranean climate region. Zooplankton, fish, and macroinvertebrates were sampled within the plants and at open-water habitats. The fis...

  10. Long-term changes of the crustacean zooplankton community in Lake Mjøsa, the largest lake in Norway

    OpenAIRE

    Løvik, Jarl Eivind; Gösta KJELLBERG

    2003-01-01

    Lake Mjøsa has been subject to an accelerating eutrophication from the 1950s to the mid 1970s, but comprehensive nutrient reduction efforts caused marked reductions of phytoplankton production and biomass during the 1980s, a process that continued during the 1990s. Zooplankton biomass and species composition was considerably affected during the eutrophication and subsequent oligotrophication. Total crustacean zooplankton biomass decreased along with decreasing algal biomass during the 1980s a...

  11. World Migration Degree Global migration flows in directed networks

    CERN Document Server

    Porat, Idan

    2015-01-01

    In this article we analyze the global flow of migrants from 206 source countries to 145 destination countries (2006-2010) and focus on the differences in the migration network pattern between destination and source counters as represented by its degree and weight distribution. Degree represents the connectivity of a country to the global migration network, and plays an important role in defining migration processes and characteristics. Global analysis of migration degree distribution offers a strong potential contribution to understanding of migration as a global phenomenon. In regard to immigration, we found that it is possible to classify destination countries into three classes: global migration hubs with high connectivity and high migration rate; local migration hubs with low connectivity and high migration rate; and local migration hubs with opposite strategy of high connectivity and low migration rate. The different migration strategies of destination countries are emerging from similar and homogenies p...

  12. Effects of acidification and cadmium pollution on the populations and habitats of limnetic zooplankton; Effekter av forsuring og kadmium-forurensning paa populasjoner og samfunn av limnisk zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Schartau, A.K.L. [Norsk Inst. for Naturforskning, Trondheim (Norway)

    1996-01-01

    The conference paper deals with executed field tests on the adding of cadmium alone or combined with acidification of an enclosed space under different nutrient and predatory conditions. The addition of cadmium changed the biomass and the composition of the phytoplankton. In combination with the added nutrient salts, the biomass of special algae increased in the Cd loaded spaces, and the addition of acid changed the effect of Cd concentration by increased production of the same. The effect of a given Cd concentration on the zooplankton varied in a wide range of environmental conditions. 22 refs., 1 tab.

  13. Environmental change and migration.

    Czech Academy of Sciences Publication Activity Database

    Stojanov, Robert

    Santa Barbara, Calif : Praeger, 2012 - (Segal, U.; Elliot, D.), s. 55-89 ISBN 978-0-313-37807-2 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : migration processes * environmental change * climate change * environmental migrants * human migration Subject RIV: AO - Sociology, Demography

  14. Effects of natural banks of free-floating plants on zooplankton community in a shallow subtropical lake in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Vanessa Gazulha

    2011-08-01

    Full Text Available The aim of this study was to test the effects of natural free-floating plants on zooplankton distribution in a shallow subtropical lake. First, the hypothesis that free-floating plants have an effect on physico-chemicals, leading to a decrease on nutrient availability and influencing the phytoplankton biomass and zooplankton community was tested. Second, the hypothesis that free-floating plants act as a refuge for zooplankton was tested. Three microhabitats were selected: free-floating plants, littoral area and open water. Results demonstrated that the effects of different microhabitats on phytoplankton biomass and physico-chemicals were not significant, indicating a weak influence of the plants. Zooplankton densities were higher in free-floating plants and littoral area, although the effect of microhabitats was weak for most of the predominant genera. The absence of free-floating plant effects on phytoplankton and physico-chemicals showed that it was not a factor influencing the microcrustacean distribution in the microhabitats. Low differences in densities of zooplankton among microhabitats and low abundance of large-bodied cladocerans led to reject the hypothesis that free-floating plants act as a refuge for zooplankton.

  15. Feeding of dominant zooplankton species and their grazing impact on autotrophic phytoplankton in the Yenisei Estuary in autumn

    Science.gov (United States)

    Drits, A. V.; Arashkevich, E. G.; Nikishina, A. B.; Sergeeva, V. M.; Solovyev, K. A.; Flint, M. V.

    2015-07-01

    Feeding of dominant mesozooplankton species was investigated in freshwater zone, estuarine frontal zone of Yenisei Estuary and adjacent inner shelf area during autumn season. Ingestion rate was estimated based on gut fluorescence measurements. It was shown that in spite on the end of productive season daily ingestion of phytoplankton for the most of the investigated freshwater, brackish and marine zooplankton species was higher than their metabolic requirements. Total phytoplankton consumption by zooplankton differed in different zones. In freshwater zone under high level of autotrophic phytoplankton biomass and primary production zooplankton grazing impact was low: 1.5% of standing stock and 20% of primary production. In the estuarine frontal zone 3.2-14.3% of standing stock and 150-290% of primary production was grazed by zooplankton per day, in adjacent inner shelf: 1.4-7.0% and 130%, accordingly. Based on comparatively analysis of obtained data and results of investigation of zooplankton feeding in Ob Estuary during the same season some general patterns of the zooplankton role in organic matter biotransformation in the large arctic rivers estuarine areas were revealed.

  16. Many Faces of Migrations

    Directory of Open Access Journals (Sweden)

    Milica Anti? Gaber

    2013-12-01

    Full Text Available Temporary or permanent, local or international, voluntary or forced, legal or illegal, registered or unregistered migrations of individuals, whole communities or individual groups are an important factor in constructing and modifying (modern societies. The extent of international migrations is truly immense. At the time of the preparation of this publication more than 200 million people have been involved in migrations in a single year according to the United Nations. Furthermore, three times more wish to migrate, mostly from sub-Saharan Africa towards some of the most economically developed areas of the world according to the estimates by the Gallup Institute (Esipova, 2011. Some authors, although aware that it is not a new phenomenon, talk about the era of migration (Castles, Miller, 2009 or the globalization of migration (Friedman, 2004. The global dimensions of migration are definitely influenced also by the increasingly visible features of modern societies like constantly changing conditions, instability, fluidity, uncertainty etc. (Beck, 2009; Bauman, 2002.The extent, direction, type of migrations and their consequences are affected by many social and natural factors in the areas of emigration and immigration. In addition, researchers from many scientific disciplines who study migrations have raised a wide range of research questions (Boyle, 2009, 96, use a variety of methodological approaches and look for different interpretations in various spatial, temporal and contextual frameworks. The migrations are a complex, multi-layered, variable, contextual process that takes place at several levels. Because of this, research on migrations has become an increasingly interdisciplinary field, since the topics and problems are so complex that they cannot be grasped solely and exclusively from the perspective of a single discipline or theory. Therefore, we are witnessing a profusion of different “faces of migration”, which is reflected and at the same time also contributed to by this thematic issue of the journal Ars & Humanitas.While mobility or migration are not new phenomena, as people have moved and migrated throughout the history of mankind, only recently, in the last few decades, has theoretical and research focus on them intensified considerably. In the last two decades a number of research projects, university programs and courses, research institutes, scientific conferences, seminars, magazines, books and other publications, involving research, academia as well as politics and various civil society organizations have emerged. This shows the recent exceptional interest in the issue of migration, both in terms of knowledge of the processes involved, their mapping in the history of mankind, as well as the theoretical development of migration studies and daily management of this politically sensitive issue.Migration affects many entities on many different levels: the individuals, their families and entire communities at the local level in the emigrant societies as well as in the receiving societies. The migration is changing not only the lives of individuals but whole communities and societies, as well as social relations; it is also shifting the cultural patterns and bringing important social transformations (Castles 2010. This of course raises a number of questions, problems and issues ranging from human rights violations to literary achievements. Some of these are addressed by the authors in this thematic issue.The title “Many faces of migration”, connecting contributions in this special issue, is borrowed from the already mentioned Gallup Institute’s report on global migration (Esipova, 2011. The guiding principle in the selection of the contributions has been their diversity, reflected also in the list of disciplines represented by the authors: sociology, geography, ethnology and cultural anthropology, history, art history, modern Mediterranean studies, gender studies and media studies. Such an approach necessarily leads not only to a diverse, but at least seemingly also incompatible,

  17. On marriage and migration.

    Science.gov (United States)

    Stark, O

    1988-09-01

    Marriage, migration, and related phenomena such as marital stability, fertility, and investment in human capital may be better explained by studying marriage and migration jointly. This paper examines the role of migration in obtaining joint labor market and marriage market equilibrium. When broadly interpreted, marriage and migration share a number of common features. Both involve search and its resolution (pairing of mates in the former and matching of labor and firms in the latter). In both cases, success in finding a partner is sensitive to the availability of partners and to the distribution of their endowments and traits. Almost always, and along with separation and divorce, marriage mandates spatial relocation which may translate into migration. Both involve a movement that is associated with adjustment costs from 1 state into another. The decisions to enter marriage and undertake employment or the decisions to divorce and quit a job depend on exogenous parameters, some of which are determined by the marriage market and the labor market. Since both marriage and divorce take place in the context of broadly defined markets, they may and often are analyzed applying market concepts, theorems, and solutions. Yet the authors could not pinpoint 1 single, systematic attempt that checks through the interactions between marriage and migration, so this paper attempts to rectify this state of research. Essentially, this paper 1) discusses individual decision making pending possible migration prior to or following marriage, 2) examines whether it is easier for a married couple or a single person to migrate, and 3) considers whether marriage dissolution could cause migration when marriage is the only reason that has kept a spouse from moving. This integrated research agenda for both marriage and migration can delineate interesting new implications to examine. PMID:12158993

  18. Phytoplankton response to winter warming modified by large-bodied zooplankton: an experimental microcosm study

    Directory of Open Access Journals (Sweden)

    Hu He

    2014-02-01

    Full Text Available While several field investigations have demonstrated significant effects of cool season (winter or spring warming on phytoplankton development, the role played by large-bodied zooplankton grazers for the responses of phytoplankton to winter warming is ambiguous. We conducted an outdoor experiment to compare the effect of winter warming (heating by 3°C in combination with presence and absence of Daphnia grazing (D. similis on phytoplankton standing crops and community structure under eutrophic conditions. When Daphnia were absent, warming was associated with significant increases in phytoplankton biomass and cyanobacterial dominance. In contrast, when Daphnia were present, warming effects on phytoplankton dynamics were offset by warming-enhanced grazing, resulting in no significant change in biomass or taxonomic dominance. These results emphasize that large-bodied zooplankton like Daphnia spp. may play an important role in modulating the interactions between climate warming and phytoplankton dynamics in nutrient rich lake ecosystems.

  19. Structure, seasonal dynamics and distribution of zooplankton in lake Drukshiai in 1994

    International Nuclear Information System (INIS)

    Investigations on the zooplankton of Lake Drukshiai were carried out in 1994. There were registered 62 taxons of protozoa and 50 taxons of metazoa, and compared with the data of 1979 - 1986 the diversity of species composition decreased 2.1 times. Eurytermic and stenothermic thermophylic species prevailed in the plankton biocenosis. In protozooplankton dominated ciliates of subclasses teolotricha and spirotricha, in metazooplankton -planctonic crustacea (Copopeda and Cladocera). Rotifers (Rotaria) were abundant only in the shallow and heated water outlet area. Seasonal dynamics of protozooplankton indicated one maximum in spring and metazooplankton - in summer. High diferentiation in quantity and biomass of zooplankton in the lake revealed different level of eutrophication of some areas. (author). 7 refs., 5 figs

  20. A Generic Process Migration Algorithm

    OpenAIRE

    Amirreza Zarrabi

    2012-01-01

    Process migration has been advocated as a means of improving multicomputer configuration performance. The optimized migration algorithm utilized in migration event has direct effect on the efficiency and deployment of the process migration system. However, every design has preference factors results in concentration on specific aspect of the migration algorithm. There is no generic migration algorithm which could satisfy all circumstances with almost reasonable costs. This paper reviews the...

  1. Eclipse effects on field crops and marine zooplankton: the 29 March 2006 Total Solar Eclipse

    OpenAIRE

    Economou, G; E. D. Christou; Giannakourou, A.; Gerasopoulos, E.; Georgopoulos, D; Kotoulas, V.; Lyra, D.; N. Tsakalis; Tziortzou, M.; P. Vahamidis; E. Papathanassiou; Karamanos, A.

    2008-01-01

    Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 a...

  2. Zooplankton characterisation of Pampean saline shallow lakes, habitat of the Andean flamingoes

    OpenAIRE

    José de Paggi, Susana B.; Marcelo Romano; Juan C. Paggi; Ignacio Barberis; Yamila S. Battauz

    2013-01-01

    The lowland saline shallow lakes in the Pampa de las Lagunas (Argentina), constitute an important habitat for flamingoes Phoenicopterus chilensis Molina and Phoenicoparrus andinus (Philippii). Little is known about the zooplankton communities of these systems, and their relationships with the temporal and spatial distribution of flamingoes. Ten shallow lakes in the Pampean region were studied in 2009 and 2010 winters, and in 2010 summer in order to assess the abundance, size and biomass of zo...

  3. Physical-chemical parameters and zooplankton community structure of the Odra oxbow in the spring season

    OpenAIRE

    ?awniczak, Jacek; ?widnicki, Kasper; Wi?niewska, Ma?gorzata; Bodzioch, Adam; Kuczy?ska-Kippen, Natalia

    2008-01-01

    The examination of the distribution of rotifers and crustaceans between particular stations located within vegetated (zones of helophytes and nymphaeids) and unvegetated (open water area) zones of an oxbow lake situated within the River Odra valley was carried out during the period of high water level in April of 2007. The obtained results revealed a considerable species diversity along with low densities of particular zooplankton species, which are characteristic features for ...

  4. Stability and bifurcation in a two harmful phytoplankton-zooplankton system

    International Nuclear Information System (INIS)

    In this paper, a mathematical model consisting of two harmful phytoplankton and zooplankton with discrete time delays is considered. We prove that a sequence of Hopf bifurcations occur at the interior equilibrium as the delay increases. Meanwhile, the phenomenon of stability switches is found under certain conditions. The direction of the Hopf bifurcations and the stability of the bifurcating periodic solutions are determined by using the theory of normal form and center manifold. Numerical simulations are given to support the theoretical results.

  5. Carbon partitioning in the food web of a high mountain lake: from bacteria to zooplankton

    Directory of Open Access Journals (Sweden)

    Alessandra PUGNETTI

    1999-08-01

    Full Text Available The organisms of the microbial loop in Lake Paione Superiore (LPS, a high mountain lake in the Italian Alpine region, were studied together with phytoplankton and zooplankton for three successive years. The biomass of bacteria, HNF (heterotrophic nanoflagellates, ciliates and phytoplankton, as mean carbon concentration in the three years, was 30 and 37 ?g C l-1 near the surface (SUR and the bottom (BOT respectively. Under the ice-cover the mean biomass carbon decreased especially at the BOT, whereas at SUR the decrease was less evident due to the maintenance of higher phytoplankton biomass (mixotrophic flagellates. In LPS ~50% of the carbon was confined in bacteria, 20% in protozoa and 30% in phytoplankton. The ratio Autotrophs/Heterotrophs was lower than 1 (mean: 0,97 at SUR and 0,58 at BOT thus indicating a system with a predominance of the heterotrophs. This might be the result of light inhibition of algal growth coupled to a production of dissolved carbon, utilized by bacteria. During late summer the peak of Daphnia longispina, the main component of the zooplankton of LPS, increased the carbon content in the lake to a total of 158 and 300 ?g C l-1 in 1997 and 1998 respectively. At the late summer peaks, zooplankton represented from 78 to 89% of the total carbon of the pelagic communities. Furthermore, the presence of Daphnia could be responsible for a decrease in the biomass carbon of a variety of organisms (algae, protozoa and bacteria. It may be possible that this is an instance of zooplankton grazing on algae, protozoa and also bacteria, as Daphnia has very broad niches and may eat pico-, nanoplankton and small ciliates. In the oligotrophic LPS, a diet which also includes protozoa could give Daphnia a further chance of survival, as ciliates are an important source of fatty acids and sterols.

  6. Responses of Phyto- and Zooplankton Communities to Prymnesium polylepis (Prymnesiales) Bloom in the Baltic Sea

    OpenAIRE

    Gorokhova, Elena; Hajdu, Susanna; Larsson, Ulf

    2014-01-01

    A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007 – spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypothe...

  7. Seasonal composition and population density of zooplankton in Lake Timsah, Suez Canal, Egypt:

    OpenAIRE

    El-Sherbiny, Mohsen M.; Al-Aidaroos, Ali M.; Ali Gab-Alla

    2011-01-01

    Zooplankton composition and abundance were investigated seasonally at ten sites in Lake Timsah and the adjacent, connected western lagoon in relation to the physico-chemical conditions. A total of 42 taxa (including larval stages) were identified, among them 21 species of copepods, 6 rotifers, 5 cladocerans, 1 chaetognath and 1 urochordate. Copepods represented the predominant component (77.7% of the total community), followed by rotifers, molluscs, cladocerans and (9.2, 4.7 and 3.9% respecti...

  8. 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 in order to identify main species in the in situ size frequency distributions obtained by the submersible version of the OPC. Differences in the particle concentration between shallow and deep water lay...

  9. Metal and proton toxicity to lake zooplankton: a chemical speciation based modelling approach

    OpenAIRE

    Stockdale, Anthony; Tipping, Edward; Lofts, Stephen; Fott, Jan; Garmo, Oyvind A.; Hruska, Jakub; Keller, Bill; Lofgren, Stefan; Maberly, Stephen C; Majer, Vladimir; Nierzwicki-Bauer, Sandra A.; Persson, Gunnar; Schartau, Ann-Kristin; Stephen J. Thackeray; Valois, Amanda

    2014-01-01

    The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. ...

  10. Trace metal concentrations in zooplankton from the eastern Arabian Sea and western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Rejomon, G.; Balachandran, K.K; Nair, M.; Joseph, T.; DineshKumar, P.K; Achuthankutty, C; Nair, K.K.C; Pillai, N.G.K

    , 2000 mu g g sup(-1); Cd, 18.7 mu g g sup(-1); and Pb, 6.55 mu g g sup(-1)) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 mu g g sup(-1); Co, 14.2 mu g g sup(-1); Ni, 18.6 mu g g sup(-1); Cu, 21.5 mu g g sup...

  11. Spatial interaction among nontoxic phytoplankton, toxic phytoplankton, and zooplankton: emergence in space and time.

    OpenAIRE

    Roy, S

    2008-01-01

    In homogeneous environments, by overturning the possibility of competitive exclusion among phytoplankton species, and by regulating the dynamics of overall plankton population, toxin-producing phytoplankton (TPP) potentially help in maintaining plankton diversity—a result shown recently. Here, I explore the competitive effects of TPP on phytoplankton and zooplankton species undergoing spatial movements in the subsurface water. The spatial interactions among the species are represented in the ...

  12. Interaction among Non-toxic Phytoplankton, Toxic Phytoplankton and Zooplankton: Inferences from Field Observations

    OpenAIRE

    Roy, S; Bhattacharya, S.; Das, P; Chattopadhyay, J.

    2007-01-01

    We explore the mutual dependencies and interactions among different groups of species of the plankton population, based on an analysis of the long-term field observations carried out by our group in the North-West coast of the Bay of Bengal. The plankton community is structured into three groups of species, namely, non-toxic phytoplankton (NTP), toxic phytoplankton (TPP) and zooplankton. To find the pair-wise dependencies among the three groups of plankton, Pearson and partial correlation coe...

  13. Effects of perfluorooctane sulfonate and perfluorooctanoic acid on the zooplanktonic community.

    Science.gov (United States)

    Sanderson, Hans; Boudreau, Timothy M; Mabury, Scott A; Solomon, Keith R

    2004-05-01

    This comparative survey summarizes six individual studies on the ecological effects of two common perfluorinated surfactants, PFOS and PFOA, on zooplankton. We compare the test designs and quantify the relative sensitivity and statistical power (1-beta > or = 0.8). The survey compares 30-L indoor microcosm to 12,000-L outdoor microcosm experiments, with 225-mL single species laboratory tests as reference. By this we elucidate the extrapolation of ecological effects in space and complexity. Generally, zooplankton had lower tolerance toward PFOS than toward PFOA. With increasing concentrations the zooplankton community became simplified toward more robust rotifer species, which, as an indirect effect, increased their abundance due to a shift in competition and predation. The statistical power of the designs exhibits inverse proportionality between complexity and realism, indoor microcosm>outdoor microcosm. Surprisingly, the 30-L study had a lower LOEC value for Daphnia magna than the laboratory chronic test, indicating that D. magna and D. pulicaria were not the most sensitive species and that laboratory tests are not always conservative relative to microcosm experiments. Food scarcity due to phytotoxicity was not the reason for the difference. PMID:15087165

  14. Zooplankton biomass and electron transport system activity around the Balearic Islands (western Mediterranean)

    Science.gov (United States)

    Herrera, A.; Gómez, M.; Packard, T. T.; Fernández de Puelles, M. L.

    2014-03-01

    Measuring electron transport system (ETS) activity in zooplankton provides an index of respiration, theoretically, the potential respiration rate. We apply the ETS technique to estimate potential respiration and carbon demand from the zooplankton community in the upper 200 m of the water column near the Balearic Islands. The investigation was focused on two areas with different oceanographic conditions: the Balearic and Algerian subbasins. It compared the biomass, potential respiration and specific potential respiration of different size fractions (53-200, 200-500, > 500 ?m) in both areas. In these regions the largest contribution to respiration was found in the larger sizes. The specific respiration (per unit biomass) was greater in smaller fractions, indicating that they have a more active metabolism. Both biomass and potential respiration increased in the Algerian subbasin and for both regions biomass and potential respiration were greater in shallow waters over the continental shelf (depressed (shifted down). In cultures and in eutrophic ocean waters (upwelling areas) b normally is greater than 0.75, consequently we intuit that the low value of b over the Balearic and Algerian subbasins indicates that the zooplankton is not well fed and that they are living under oligotrophic stress.

  15. Reprint of “Zooplankton biomass and electron transport system activity around the Balearic Islands (western Mediterranean)”

    Science.gov (United States)

    Herrera, A.; Gómez, M.; Packard, T. T.; Fernández de Puelles, M. L.

    2014-10-01

    Measuring electron transport system (ETS) activity in zooplankton provides an index of respiration, theoretically, the potential respiration rate. We apply the ETS technique to estimate potential respiration and carbon demand from the zooplankton community in the upper 200 m of the water column near the Balearic Islands. The investigation was focused on two areas with different oceanographic conditions: the Balearic and Algerian subbasins. It compared the biomass, potential respiration and specific potential respiration of different size fractions (53-200, 200-500, > 500 ?m) in both areas. In these regions the largest contribution to respiration was found in the larger sizes. The specific respiration (per unit biomass) was greater in smaller fractions, indicating that they have a more active metabolism. Both biomass and potential respiration increased in the Algerian subbasin and for both regions biomass and potential respiration were greater in shallow waters over the continental shelf (depressed (shifted down). In cultures and in eutrophic ocean waters (upwelling areas) b normally is greater than 0.75, consequently we intuit that the low value of b over the Balearic and Algerian subbasins indicates that the zooplankton is not well fed and that they are living under oligotrophic stress.

  16. Quantifying Preferences and Responsiveness of Marine Zooplankton to Changing Environmental Conditions using Microfluidics

    Science.gov (United States)

    Merten, Christoph A.; Arendt, Detlev

    2015-01-01

    Global environmental change significantly affects marine species composition. However, analyzing the impact of these changes on marine zooplankton communities was so far mostly limited to assessing lethal doses through mortality assays and hence did not allow a direct assessment of the preferred conditions, or preferendum. Here, we use a microfluidic device to characterize individual behavior of actively swimming zooplankton, and to quantitatively determine their ecological preferendum. For the annelid zooplankton model Platynereis dumerilii we observe a broader pH preferendum than for the copepod Euterpina acutifrons, and reveal previously unrecognized sub-populations with different pH preferenda. For Platynereis, the minimum concentration difference required to elicit a response (responsiveness) is ~1 ?M for H+ and ~13.7 mM for NaCl. Furthermore, using laser ablations we show that olfactomedin-expressing sensory cells mediate chemical responsiveness in the Platynereis foregut. Taken together, our microfluidic approach allows precise assessment and functional understanding of environmental perception on planktonic behaviour. PMID:26517120

  17. Zooplankton community resilience and aquatic environmental stability on aquaculture practices: a study using net cages.

    Science.gov (United States)

    Dias, J D; Simões, N R; Bonecker, C C

    2012-02-01

    Fish farming in net cages causes changes in environmental conditions. We evaluated the resilience of zooplankton concerning this activity in Rosana Reservoir (Paranapanema River, PR-SP). Samples were taken near the net cages installed at distances upstream and downstream, before and after net cage installation. The resilience was estimated by the decrease in the groups' abundance after installing the net cages. The zooplankton community was represented by 106 species. The most abundant species were Synchaeta pectinata, S. oblonga, Conochilus coenobasis, Polyarthra dolichoptera and C. unicornis (Rotifera), Ceriodaphnia cornuta, Moina minuta, Bosmina hagmanni and C. silvestrii (Cladocera) and Notodiaptomus amazonicus (Copepoda). The resilience of microcrustaceans was affected in the growing points as this activity left the production environment for longer, delaying the natural ability of community responses. Microcrustaceans groups, mainly calanoid and cyclopoid copepods, had a different return rate. The net cage installation acted as a stress factor on the zooplankton community. Management strategies that cause fewer risks to the organisms and maximize energy flow may help in maintaining system stability. PMID:22437379

  18. Evidence of microplastics in samples of zooplankton from Portuguese coastal waters.

    Science.gov (United States)

    Frias, J P G L; Otero, V; Sobral, P

    2014-04-01

    Records of high concentrations of plastic and microplastic marine debris floating in the ocean have led to investigate the presence of microplastics in samples of zooplankton from Portuguese coastal waters. Zooplankton samples collected at four offshore sites, in surveys conducted between 2002 and 2008, with three different sampling methods, were used in this preliminary study. A total of 152 samples were processed and microplastics were identified in 93 of them, corresponding to 61% of the total. Costa Vicentina, followed by Lisboa, were the regions with higher microplastic concentrations (0.036 and 0.033 no. m?³) and abundances (0.07 and 0.06 cm³ m?³), respectively. Microplastic: zooplankton ratios were also higher in these two regions, which is probably related to the proximity of densely populated areas and inputs from the Tejo and Sado river estuaries. Microplastics polymers were identified using Micro Fourier Transformed Infrared Spectroscopy (?-FTIR), as polyethylene (PE), polypropylene (PP) and polyacrylates (PA). The present work is the first report on the composition of microplastic particles collected with plankton nets in Portuguese coastal waters. Plankton surveys from regular monitoring campaigns conducted worldwide may be used to monitor plastic particles in the oceans and constitute an important and low cost tool to address marine litter within the scope of the Marine Strategy Framework Directive (2008/56/EC). PMID:24461782

  19. Biotic Spectrum of Chando Lake in Context of Ecological Status and Zooplankton Diversity

    Directory of Open Access Journals (Sweden)

    Anuradha Shukla

    2012-11-01

    Full Text Available Covering an area of approximate 650 ha, Chando Lake is located in South East of Basti, (U.P.. No precise study regarding its hydrobiology has been conducted. Hence, present study has been undertaken to observe its ecological status and zooplankton diversity from June 2010 to May 2012. The early mean flow in this lake relied on rains and the mean annual rain fall was recorded to be 1094 cm with in 51 average rainy days. The average value of the temperature was recorded to be 28.46°C, pH 7.38, transparency 58.52 cm, DO 6024 mg/L, free CO2 3.70 mg/L, TDS 1 52.20 mg/L, total hardness 153.69 mg/L , total alkalinity 272.44 mg/L , Nitrate 7.11 mg/L, phosphate 0.83 mg/L and chloride 34.63 mg/L. In the present study 23 species of zooplankton were noticed out of which six species belong to cladocerans, six species of copepods, four species of protozoans and seven species of rotiferans. The study of zooplankton species diversity and abundance with respect to biotic factors may assist in future planning for the management of intensive fish culture in this vast lake.

  20. Estimation of the toxicity of pollutants to marine phytoplanktonic and zooplanktonic organisms

    International Nuclear Information System (INIS)

    One of the basic components of the action plans sponsored by UNEP in the framework of the Regional Seas Programme is the assessment of the state of the marine environment and of its resources, and of the sources and trends of the pollution, and the impact of pollution on human health, marine ecosystems, and amenities. In order to ensure that the data obtained through this assessment can be compared on a world-wide basis and thus contribute to the Global Environment Monitoring System (GEMS) of UNEP, a set of Reference Methods and Guidelines for marine pollution studies are being developed as part of a programme of comprehensive technical support which includes the provision of expert advice, reference methods and materials, training and data quality assurance. This reference method describes procedures for estimating the toxicity of pollutants to marine phytoplankton and zooplankton. Procedures are given for estimating the media effective concentrations (EC50) of toxicants to phytoplankton, and the minimum algistatic concentration (MAC-5). For zooplankton, procedures are given for determining median lethal concentrations. Organisms are exposed to each of a range of concentrations of the test substance. For phytoplankton, the median effective concentration (EC50) is estimated in terms of the number of individuals surviving, the biomass of individuals surviving, or the chlorophyll content of the individuals surviving. For zooplankton, the media lethal concentration (LC50) is estimated by conventional log-probit analysis of the mortality data

  1. Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish

    Directory of Open Access Journals (Sweden)

    W. Ekau

    2010-05-01

    Full Text Available Dissolved oxygen (DO concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 mL O2 L?1 through impacted growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 mL O2 L?1. A change in the average or the range of DO may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity.

    Evidence for the deleterious effects of oxygen depletion on pelagic species is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with variable DOs and exploit adaptive mechanisms, nektonic species may avoid areas of unfavourable DO and develop adapted migration strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ. In shallow areas only the surface layer can serve as a refuge, but in deep waters many organisms have developed vertical migration strategies to use, pass through and cope with the OMZ.

    This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity. We describe processes in two contrasting systems, the semi-enclosed Baltic Sea and the coastal upwelling system of the Benguela Current to demonstrate the consequences of increasing hypoxia on ecosystem functioning and services.

  2. Impacts of hypoxia on the structure and processes in the pelagic community (zooplankton, macro-invertebrates and fish

    Directory of Open Access Journals (Sweden)

    W. Ekau

    2009-05-01

    Full Text Available Dissolved oxygen (DO concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 ml L?1 and show impact on growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 ml L?1. A change in the average or the minimum or maximum DO in an area may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity.

    Evidence of the deleterious effects of oxygen depletion on species of the pelagic realm is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with different DOs and find adaptive mechanisms, nektonic species may avoid areas of inconvenient DO and develop adapted migrational strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ. In shallow areas only the surface layer can serve as a refuge, in deep waters many organisms have developed vertical migration strategies to use, pass and cope with the OMZ.

    This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity.

  3. Stable oxygen and hydrogen isotope analyses of bowhead whale baleen as biochemical recorders of migration and arctic environmental change

    Science.gov (United States)

    deHart, Pieter A. P.; Picco, Candace M.

    2015-06-01

    An analysis of the stable isotopes of oxygen (?18O) and hydrogen (?D) was used to examine the linkage between sea ice concentration and the migration of western arctic bowhead whales (Balaena mysticetus; WABW). We compared ?18O and ?D variability along the length of WABW baleen with isotopic values of zooplankton prey from different WABW habitat, with published ?13C and ?15N data, and with historical sea ice records. Zooplankton signatures varied widely (?18O = -13‰-56‰; ?D = -220‰ to -75‰), with regional separation between winter (Bering Sea) and summer (eastern Beaufort Sea) habitats of WABW observable in ?D. The ?18O and ?D of WABW varied significantly along the length of baleen (?18O = 8-18‰; ?D = -180 to -80‰), confirming seasonal migration and reflecting distinct regional dietary variation in isotopes. WABW migration appears to have varied concomitant with temporal sea ice concentration (SIC) changes; in years with high SIC, the difference in ?D of WABW baleen between seasonal habitats was significantly greater than low SIC periods. This work shows that SIC is not only a determinant of habitat accessibility for WABW, but baleen may also be a record of historical SIC and Arctic climate.

  4. Interactions between benthic predators and zooplanktonic prey are affected by turbulent waves.

    Science.gov (United States)

    Robinson, H E; Finelli, C M; Koehl, M A R

    2013-11-01

    Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones, increases in these aspects of flow have been shown to enhance feeding rates and efficiency of motile benthic fish that lunge out of their burrows to catch zooplankton. Faster, more turbulent flow interferes with the ability of prey to detect predators and execute escape maneuvers, and thus enhances capture rates both for passive suspension-feeding predators and for actively swimming predators. However, prey captured in the mouths of fish are not washed away by ambient flow, whereas prey captured on the tentacles of suspension feeders can be swept off before they are ingested. Therefore, the effects of flowing water on predation on zooplankton by benthic animals depend on the feeding mode of the predator. PMID:23942646

  5. Vertical muon flux

    International Nuclear Information System (INIS)

    A derivation of the vertical flux of muons generated by a hadron cascade in the atmosphere is presented. It is supposed that the hadron cascade is only composed by charged nucleons and pions and it is assumed the free particle model to describe the hadron cascade development in the atmosphere

  6. Migration of cells in the rat corneal epithelium

    International Nuclear Information System (INIS)

    The migration of cells in the rat corneal epithelium was studied using continuous labelling with tritiated thymidine [3H]TdR, during a 24 h period. Most mitoses resulted in 2 new basal cells. Cells leaving the basal cell layer moved vertically to the surface in all areas of the corneal epithelium. The first labelled cells reached the surface 3 days after the first injection of [3H]TdR. No stream of cells from the conjunctiva to the cornea in the limbal areas was observed, and no centripetal migration of epithelial cells in the cornea could be observed. After a cell has lost its attachment to the basement membrane, it is committed to be exfoliated in a few days without undergoing mitosis. Thus the slow centripetal migration of epithelial cells and the exchange of centrally located cells, as indicated by clinical findings and experimental studies, can only be explained by migration of basal cells. (author)

  7. Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web

    International Nuclear Information System (INIS)

    There is a well documented accumulation of mercury in fish to concentrations of concern for human consumption. Variation in fish Hg burden between lakes is often high and may result from differences in Hg transfer through lower levels of the food web where mercury is bioconcentrated to phytoplankton and transferred to herbivorous zooplankton. Prior research derived patterns of mercury accumulation in freshwater invertebrates from field collected animals. This study provides results from controlled mesocosm experiments comparing the effects of zooplankton composition, algal abundance, and the chemical speciation of mercury on the ability of zooplankton to accumulate mercury from phytoplankton and transfer that mercury to planktivores. Experiments were conducted in 550-L mesocosms across a gradient of algal densities manipulated by inorganic nutrient additions. Enriched, stable isotopes of organic (CH3200HgCl) and inorganic (201HgCl2) mercury were added to mesocosms and their concentrations measured in water, seston, and three common zooplankton species. After 2 weeks, monomethylmercury (MMHg) concentrations were two to three times lower in the two copepod species, Leptodiaptomus minutus and Mesocyclops edax than in the cladoceran, Daphnia mendotae. All three zooplankton species had higher MMHg concentrations in mesocosms with low versus high initial algal abundance. However, despite higher concentrations of inorganic mercury (HgI) in seston from low nutrient mesocosms, there were no significant differences in the HgI accumulated by zooplankton across nutrient treatments. Bioaccumulation factors for MMHg in the plankton were similar to those calculated for plankton in natural lakes and a four-compartment (aqueous, seston, macrozooplankton, and periphyton/sediments) mass balance model after 21 days accounted for ?18% of the CH3200Hg and ?33% of the 201Hg added. Results from our experiments corroborate results from field studies and suggest the importance of particular zooplankton herbivores (e.g., Daphnia) in the transfer of Hg to higher trophic levels in aquatic food webs

  8. Global Governance of Migration

    OpenAIRE

    Rustamov, Sirus

    2011-01-01

    The aim of this thesis is to analyze the recently formed global governance of migration, which has got an unprecedented trans-boundary nature due to the impacts og globalization in the post Cold War era. 

  9. Community structure of zooplankton in the main entrance of Bahía Magdalena, México during 1996

    Scientific Electronic Library Online (English)

    Jaime, Gómez-Gutiérrez; Ricardo, Palomares-García; Sergio, Hernández-Trujillo; Azucena, Carballido-Carranza.

    2001-06-01

    Full Text Available La estructura de la comunidad de zooplancton, incluyendo copépodos, eufáusidos, quetognatos y larvas de decápodos, fue monitoriada por seis ciclos circadianos usando muestras de redes Bongo (red de 500 mm de poro) de bahía Magdalena, en la costa suroeste de Baja California, México. Las muestras se o [...] btuvieron durante tres viajes oceanográficos (marzo, julio y diciembre de 1996) para describir los cambios en la estructura de la comunidad de zooplancton por toda la boca principal de la bahía Magdalena. La estructura de la comunidad de zooplancton mostró cambios fuertes con una relación cercana a las condiciones ambientales. Durante marzo, una columna de agua bien mezclada con baja temperatura y salinidad indicó una influencia del agua de la Corriente de California y de procesos de afloramiento local. Durante julio, la temperatura aumentó y se registró un ámbito de de salinidad amplio. La estratificación de la columna de agua fue intensa durante el verano, realzando la termoclina. Las temperatura y salinidad más altas fueron registradas en diciembre, relacionadas a la presencia de la Corriente Costera de Costa Rica (CRCC). La termoclina se hizo más profunda al aumentar la temperatura del agua. Una estructura de una comunidad templada típica con una riqueza específica baja denominada por Calanus pacificus, Nyctiphanes simplex y Acartia clausi y una biomasa de zooplancton alta (promedio 9.3 y 5.5 ml 1000 m-3 respectivamente) durante marzo y julio cambió a una estructura de una comunidad tropical más compleja con biomasa de zooplanton baja en diciembre (promedio 0.37 ml 1000 m-3). La boca de la bahía Magdalena tiene un intercambio vigoroso de agua causado por corrientes. La estructura de la comunidad de zooplancton no fue significantemente diferente entre la parte central de la bahía Magdalena y la plataforma continental afuera de la bahía en todos los meses. Los resultados sugieren una interacción de adentro hacia afuera más dinámica de los grupos de zooplancton que los antes pensado. Abstract in english The zooplankton community structure, including copepods, euphausiids, chaetognaths, and decapod larvae, was monitored during six circadian cycles using Bongo net (500 *m mesh net) samples from Bahía Magdalena, on the southwest coast of Baja California, México. Samples were obtained during three ocea [...] nographic surveys (March, July, and December 1996) to describe the changes in the zooplankton community structure throughout the main mouth of Bahía Magdalena. The zooplankton community structure showed strong changes with a close relation to environmental conditions. During March, a well-mixed water column with low temperature and salinity indicated an influence of the California Current water and local upwelling processes. During July, temperature increased a nd a wide salinity range was recorded. The stratification of the water column was intense during summer, enhancing the thermocline. The highest temperatures and salinity were recorded in December, related to the presence of the Costa Rica Coastal Current (CRCC). The thermocline deepened as water temperature increased. A typical temperate community structure with low specific richness dominated by Calanus pacificus, Nyctiphanes simplex, and Acartia clausi and high zooplankton biomass (average 9.3 and 5.5 ml 1000 m-3respectively) during March and July shifted to a more complex tropical community structure with a low zooplankton biomass in December (average 0.37 ml 1000 m-3). The mouth of Bahía Magdalena has a vigorous exchange of water caused by tidal currents. The zooplankton community structure was not significantly different between the central part of Bahía Magdalena and the continental shelf outside the bay for all months. The results suggest a more dynamic inside-outside interaction of zooplankton assemblages than first thought.

  10. Employment Protection and Migration

    OpenAIRE

    Bazillier, Rémi; Moullan, Yasser

    2012-01-01

    We argue in this paper that labor market institutions, and more particularly employment protection (EPL), are an important determinant of migration. Using a bilateral migration database, we empirically show that the employment protection di fferential has a negative impact on bilateral ows. Contrary to pop- ular wisdom which assumes that migrants look for a more protected market, we show that migrants tend to move to countries where employment protection is close to that of their country of o...

  11. Migration and culture

    OpenAIRE

    Epstein, Gil S.; Gang, Ira N.

    2010-01-01

    Culture is not new to the study of migration. It has lurked beneath the surface for some time, occasionally protruding openly into the discussion, usually under some pseudonym. The authors bring culture into the open. They are concerned with how culture manifests itself in the migration process for three groups of actors: the migrants, those remaining in the sending areas, and people already living in the recipient locations. The topics vary widely. What unites the authors is an understanding...

  12. International Migration of Couples

    DEFF Research Database (Denmark)

    Munk, Martin D.; Junge, Martin; Poutvaara, Panu

    2015-01-01

    We develop a theoretical model regarding the migration of dual-earner couples and test it in the context of international migration. Our model predicts that the probability that a couple emigrates increases with the income of the primary earner, whereas the income of the secondary earner may affect the decision in either direction. We conduct an empirical analysis that uses population-wide administrative data from Denmark, and the results are consistent with our model. We find that primary earne...

  13. Migration = cloning; aliasiing

    DEFF Research Database (Denmark)

    Hüttel, Hans; Kleist, Josva; Nestmann, Uwe; Merro, Massimo

    1999-01-01

    In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider the creation of object surrogates as an abstraction of the abovementioned style of migration. We introduce Øjeblik, a distribution-free subset of Obliq, and provide three different configuration-style semantics, ...

  14. Migration og etnicitet

    DEFF Research Database (Denmark)

    Christiansen, Connie Carøe

    2004-01-01

    Migration og etnicitet er aktuelle og forbundne fænomener, idet migration øger berøringsfladerne mellem befolkningsgrupper. Etniciteter formes i takt med at grænser drages imellem disse grupper. Imod moderniserings-teoriernes forventning forsvandt etnicitet ikke som en traditionel eller oprindelig måde at skabe tilhørsforhold på; globalt set fremstår vor tid istedet som en "migrationens tidsalder", der tilsyneladende også er en tidsalder, hvor kulturelle særtræk, i form af etnicitet, udgør vigti...

  15. Migration, Narration, Identity

    DEFF Research Database (Denmark)

    Leese, Peter

    2013-01-01

    (co-editor with Carly McLaughlin and Wladyslaw Witalisz) This book presents articles resulting from joint research on the representations of migration conducted in connection with the Erasmus Intensive Programme entitled «Migration and Narration» taught to groups of international students over three consecutive summers from 2010 to 2012. The articles focus on various aspects of the migrant experience and try to answer questions about migrant identity and its representations in literature and the...

  16. Migrating for a Profession

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2015-01-01

    Youths from the Global South migrating for further education often face various forms of discrimination. This Caribbean case study discusses how conditions in the home country can provide a foundation for educational migration that helps the migrants overcome such obstacles and even develop a strong sense of agency and self-empowerment. In the post-WWII period, numerous Caribbean women trained in nursing at British hospitals that have been described as marred by race and gender related inequalit...

  17. Migration, klima og sundhed

    DEFF Research Database (Denmark)

    Tellier, Siri; Carballo, Manuel

    2009-01-01

    Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which environmental refugees find themselves and the consequences this may have. Finally, it points to the urgent need to reform health systems in both developing and developed countries to adapt to rapidly changing ...

  18. Samtidskunst og migration

    DEFF Research Database (Denmark)

    Petersen, Anne Ring

    2010-01-01

    "Samtidskunst og migration. En oversigt over faglitteraturen" er en forskningsoversigt der gør status over hvad der hidtil er skrevet inden for det kunsthistoriske område om vor tids billedkunst og migration som politisk, socialt og kulturelt fænomen, primært i forbindelse med immigration til Europa og i bredere forstand Vesten. Rapporten er en intern rapport som er lavet i tilknytning til det kollektive forskningsprojekt "Islam i europæisk litteratur" på Afdelingen for Litteraturvidenskab og Mo...

  19. Migration of Interplanetary Dust

    OpenAIRE

    Ipatov, S. I.; Mather, J. C.; Taylor, P.A.

    2003-01-01

    We numerically investigate the migration of dust particles with initial orbits close to those of the numbered asteroids, observed trans-Neptunian objects, and Comet Encke. The fraction of silicate asteroidal particles that collided with the Earth during their lifetime varied from 1.1% for 100 micron particles to 0.008% for 1 micron particles. Almost all asteroidal particles with diameter d>4 microns collided with the Sun. The peaks in the migrating asteroidal dust particles'...

  20. Migration and malaria.

    Science.gov (United States)

    Jitthai, Nigoon

    2013-01-01

    Migration is an important global issue as poorly managed migration can result in a diversity of problems, including an increase in the transmission of diseases such as malaria. There is evidence to suggest that malaria is no longer a forest-dependent disease and may largely be affected by population movements, mostly to agricultural areas. While internal and transnational migration has different legal implications in most countries, both types of migration occur for the same reasons; economic and/ or safety. Although migration in itself is not a definitive risk for malaria, several factors can put, migrants and local communities alike, in vulnerable situations. In particular, infrastructure and rural development, deforestation for logging and economic farming, political movements, and natural disasters are some of the major factors that push and pull people in and out of malaria-endemic areas. Therefore, understanding the changing socio-environmental situation as well as population movements and their associated risks for malaria infection, is critical for malaria control, containment, and elimination. Efforts to address these issues should include advocacy, mapping exercises and expanded/ strengthened surveillance to also include migrant health information systems. Malaria related information, prevention measures, and early diagnosis and appropriate treatment should be made easily accessible for migrants regardless of their migration status; not only to ensure that they are equipped with appropriate knowledge and devices to protect themselves, but also to ensure that they are properly diagnosed and treated, to prevent further transmission, and to ensure that they are captured by the surveillance system. PMID:24159832

  1. An experimental study of turbulent flow in vertical slot fishways

    OpenAIRE

    Tarrade, Laurent; Texier, Alain; David, Laurent; Pineau, Gérard; Larinier, Michel

    2006-01-01

    The vertical slot fishways are hydraulic structures that allow the upstream migration of fishes through engineering constructions or natural obstructions in rivers. This type of pool fish pass is generally very effective in ensuring passage of the target species, particularly diadromous species. However, visual observations have shown that certain small species may be trapped in the large recirculation zones and seem to have difficulty in rapidly passing through very large pools. An experimen...

  2. Zooplankton, temperature, salinity, and nutrients data from bottle and net casts in the Flores Sea from the SAMUDERA from 14 July 1976 to 26 July 1976 (NODC Accession 0000672)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton, phytoplankton, nutrients, and other data were collected using bottles and nets from the SAMUDERA from 14 July 1976 to 26 July 1976 . Zooplankton data...

  3. AFSC/RACE/EcoFOCI - Zooplankton data collected in support of FOCI assessment surveys and ecosystem observations in the Bering, Beaufort, and Chukchi Seas and the Gulf of Alaska, 1987 – Present

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data are abundance by taxanomic group (to species where possible), stage, size and sex. Zooplankton sorting is performed at The Polish Plankton Sorting...

  4. Preliminary assessment of the zooplankton community composition in a region under the influence of a uranium mine (Caldas, Southeastern Brazil)

    International Nuclear Information System (INIS)

    The Ore Treatment Unit consists of an open cast mine (CM), its mining waste areas, facilities for the physical treatment of the ore, and a chemical treatment plant for uranium extraction. At CM, the processes of acid drainage create effluents, which are treated by chemical processes and, thereafter, disposed of in Antas dam. The objective of the present study was to make an inventory of zooplanktonic and describe the physicochemical characteristics of site CM and at the site of treated effluents disposal (site 41), located at Antas dam. Water samples were collected in October/08 and January/09, in order to describe the abiotic variables and the zooplankton community. The average values of conductivity at sites CM and 41 were 2415 and 422 ?/cm2, respectively. Values of pH at site CM remained acid, whereas, at site 41 we recorded values near neutrality. The concentrations of total nutrients at both sampling sites were higher in the rainy season. Zooplankton species richness present at site CM was lower than at site 41, and there were only two identified species Bosmina sp and Keratella americana. At site 41 we recorded more species, mainly of the Rotifera. Among Cladocera, we identified two species, regarding Copepoda, the orders Cyclopoida and Calanoida were present. At site CM the density values were lower compared to site 41. The preliminary assessment of the zooplankton community showed lower values of species richness and density at site CM, what may be probably explained by the adverse environmental conditions for zooplankton community. (author)

  5. TOWARD MIGRATION TRANSITION IN ROMANIA

    OpenAIRE

    Cristian Incaltarau

    2012-01-01

    Most studies regarding the contribution of migration to development are limited to an isolated analysis of the economic effects of migration. But the migration process is in turn influenced by other processes. So a wider framework including migration and other processes of development would be more appropriate. The experience of South European and East Asian countries have shown us that, during development, countries can change their migration profile from emigration to immigration. The prese...

  6. Globalization, Migration and Development

    Directory of Open Access Journals (Sweden)

    George, Susan

    2002-01-01

    Full Text Available EnglishMigration may become the most important branch of demography in the earlydecades of the new millennium in a rapidly globalizing world. This paper discusses the causes, costsand benefits of international migration to countries of the South and North, and key issues of commonconcern. International migration is as old as national boundaries, though its nature, volume,direction, causes and consequences have changed. The causes of migration are rooted in the rate ofpopulation growth and the proportion of youth in the population, their education and training,employment opportunities, income differentials in society, communication and transportationfacilities, political freedom and human rights and level of urbanization. Migration benefits the Souththrough remittances of migrants, improves the economic welfare of the population (particularly womenof South countries generally, increases investment, and leads to structural changes in the economy.However, emigration from the South has costs too, be they social or caused by factors such as braindrain. The North also benefits by migration through enhancement of economic growth, development ofnatural resources, improved employment prospects, social development and through exposure toimmigrants' new cultures and lifestyles. Migration also has costs to the North such as of immigrantintegration, a certain amount of destabilization of the economy, illegal immigration, and socialproblems of discrimination and exploitation. Issues common to both North and South include impact onprivate investment, trade, international cooperation, and sustainable development. Both North andSouth face a dilemma in seeking an appropriate balance between importing South's labour or itsproducts and exporting capital and technology from the North.FrenchLa migration est sans doute devenue la partie la plus importante de la démographie des premières décennies du nouveau millénaire dans un monde qui change rapidement. Ce document porte sur les causes, les coûts et les avantages de la migration internationale vers les pays du Sud et du Nord ainsi que sur les grandes préoccupations communes. La migration internationale existe depuis l'avènement des frontières nationales, bien que sa nature, son volume, sa direction ainsi que ses causes et conséquences aient changé. Les causes de la migration trouvent leur origine dans le taux de croissance d'une population, sa proportion de jeunes, leur niveau d'éducation et de formation, les occasions d'emploi, les écarts de revenu dans la société, les systèmes de communication et de transport, la liberté politique, les droits de la personne et le niveau d'urbanisation. La migration profite au Sud parce que les migrants envoient de l'argent, améliorant généralement le bien-être économique de la population (surtout celui des femmes des pays du Sud, augmentant les investissements et donne lieu à des changements structuraux de l'économie. Cependant, l'émigration du Sud a tout de même un prix, que ce soit social ou causé par des facteurs tels que l'exode des cerveaux. Le Nord profite aussi de la migration grâce à une meilleure croissance économique, l'exploitation de richesses naturelles, de meilleures possibilités d'emploi et le développement social par l'exposition aux nouvelles cultures et styles de vie des immigrants. La migration a aussi un prix pour le Nord tel que l'intégration des immigrants, une certaine déstabilisation de l'économie, l'immigration illégale ainsi que les problèmes sociaux relatifs à la discrimination et à l'exploitation. Les préoccupations communes au Sud et au Nord incluent les incidences sur les investissements privés, le commerce, la coopération internationale et le développement durable. Autant le Nord que le Sud doivent composer avec le dilemme de trouver l'équilibre entre l'importation de la main-d'œuvre du Sud.

  7. Migration of radionuclides following shallow land burial

    International Nuclear Information System (INIS)

    The site of a former nuclear laboratory and shallow land burial facility 25 km southwest of Chicago (USA) has been examined for radionuclide migration and residual radioactive materials. The radioactivity was produced during operations with the first nuclear reactors and associated research from 1943 to 1955. The chronology of events and details of the decommissioning procedures, including reactor burial, are described. Surface soil, surface water, soil borings drilled through and around the facility, and water from the dolomite aquifer and glacial till overburden were analyzed for a variety of radionuclides. The only nuclide found to have migrated out of the burial site is hydrogen-3, as tritiated water. This nuclide was detected in surface water, soil water, and nearby picnic wells. The concentrations in the wells show a seasonal fluctuation, from 0.1 nCi/t in the summer to 14 nCi/l in the recharging of the groundwater winter, that is attributed to by spring rains. Water migration rates in the glacial till and dolomite were estimated by several methods. The time of travel of water to the nearest well, 400 m from the facility, is estimated to be 58 months. The vertical and horizontal distribution of tritium in the glacial till was measured. The origin of the tritium, neutron-irradiated lithium, was established from measurements of the hydrogen isotopic ratios. Concentrations of other radionuclides in soil and water were normal, except for plutonium (at about twice fallout concentrations) in the first 2 m below the buried material. The solid-element nuclides have migrated very little. Exposure pathways and their associated doses, and procedures for retarding further migration are discUssed. (author)

  8. Vertical organic transistors

    Science.gov (United States)

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-01

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100?nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-?m structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

  9. Vertical Protocol Composition

    OpenAIRE

    Groß, Thomas; Mödersheim, Sebastian Alexander

    2011-01-01

    The security of key exchange and secure channel protocols, such as TLS, has been studied intensively. However, only few works have considered what happens when the established keys are actually used—to run some protocol securely over the established “channel”. We call this a vertical protocol composition, and it is truly commonplace in today’s communication with the diversity of VPNs and secure browser sessions. In fact, it is normal that we have several layers of secu...

  10. 'Endurance' All Around Vertical)

    Science.gov (United States)

    2004-01-01

    This 360-degree view of the terrain surrounding NASA's Mars Exploration Rover Opportunity was taken on the rover's 171st sol on Mars (July 17, 2004). It was assembled from images taken by the rover's navigation camera at a position referred to as 'site 33.' Opportunity had driven 11 meters (36 feet) into 'Endurance Crater.' The view is a vertical projection with geometrical seam correction.

  11. Vertical Protocol Composition

    DEFF Research Database (Denmark)

    Groß, Thomas; Mödersheim, Sebastian Alexander

    2011-01-01

    The security of key exchange and secure channel protocols, such as TLS, has been studied intensively. However, only few works have considered what happens when the established keys are actually used—to run some protocol securely over the established “channel”. We call this a vertical protocol composition, and it is truly commonplace in today’s communication with the diversity of VPNs and secure browser sessions. In fact, it is normal that we have several layers of secure channels: For instance, ...

  12. Radially Magnetized Protoplanetary Disk: Vertical Profile

    Science.gov (United States)

    Russo, Matthew; Thompson, Christopher

    2015-11-01

    This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field Br ? (10?4–10?2)(r/ AU)?2 G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ?1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10?8 M? yr?1 are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper.

  13. Biodiversity of zooplankton communities in the Upper Paraná River floodplain: interannual variation from long-term studies Biodiversidade de comunidades de zooplâncton na planície de inundação do Alto Rio Paraná: variações interanuais em estudos de longa duração

    OpenAIRE

    FA Lansac-Tôha; CC. Bonecker; LFM. Velho; NR. Simões; JD Dias; GM. Alves; EM. Takahashi

    2009-01-01

    We investigated the effect of interannual variation of hydrosedimentological regime and connectivity on the zooplankton biodiversity in the Upper Paraná River floodplain. Zooplankton samplings were undertaken between 2000 and 2007, in different environments of the floodplain, including connected and isolated floodplain lakes, backwaters, rivers and channels. The zooplankton included 541 species. Rotifers showed the highest species richness and abundance. Among the zooplankton species, 71 repr...

  14. Behind the impact of introduced trout in high altitude lakes: adult, not juvenile fish are responsible of the selective predation on crustacean zooplankton

    Directory of Open Access Journals (Sweden)

    Rocco Tiberti

    2014-05-01

    Full Text Available Introduced fish seriously affect zooplankton communities in mountain lakes, often leading to the loss of large species. Selective predation is recognized to be the ultimate cause of such a strong impact. Here we describe the selection of zooplankton prey by analyzing the stomach contents of more than 300 brook trout (Salvelinus fontinalis inhabiting seven alpine lakes in the Gran Paradiso National Park (western Italian Alps. Our results show that planktivory is much more common in young fish, which feed on a larger number of taxa, but also adult fish maintain the ability to feed on zooplankton. There is a direct dependence between the length of zooplankton prey and the length of their fish predators, and adult, not juvenile fish are responsible of the selective predation on large crustacean zooplankton, which drive the impact of introduced fish throughout the entire zooplankton community. In some rare cases, large zooplankton populations develop in the presence of brook trout, and planktivory can become an important temporary resource for adult fish during the ice-free season. Thus, in the early stages of the establishment of non-native trout in alpine lakes, large-bodied zooplankton may represent an important food resource.

  15. Effects of experimental eutrophization on zooplankton community / Efeitos da eutrofização experimental sobre a comunidade zooplanctônica

    Scientific Electronic Library Online (English)

    Ana Maria Alves de, Medeiros; Cyntya Eustáquio de, Sousa; Maria Cristina, Crispim; Ana Karla Araújo, Montenegro.

    2013-06-01

    Full Text Available OBJETIVOS: O presente estudo avaliou os efeitos do aumento na concentração de nutrientes sobre a comunidade zooplanctônica, através de experimentos laboratoriais. MÉTODOS: Os experimentos foram realizados em laboratório, onde três estados tróficos foram simulados, a saber, mesotrófico, eutrófico e h [...] ipereutrófico. Cada tratamento foi replicado três vezes, e indivíduos de Brachionus urceolaris (10 indivíduos), Hexarthra mira (5) (Rotifera), Latonopsis sp. (10), Moina minuta (10) (Cladocera) e Thermocyclops sp. (5) (Copepoda) foram introduzidos em cada réplica. Durante o primeiro dia de experimento, e a cada sete dias de intervalo durante 14 dias (totalizando três amostragens), toda a água foi coletada de cada aquário e filtrada, para a determinação das densidades de cada espécie de zooplâncton. MANOVAs duas vias e ANOVAs de uma via foram empregadas para a determinação das variações nas densidades de zooplâncton entre os tratamentos e ao longo do período de estudo. Ainda, Modelos Lineares Generalizados (MLGs) foram empregados para avaliar como fatores ambientais que influenciaram a densidade do zooplâncton. A composição do fitoplâncton foi determinada no ínicio e no final do experimento. RESULTADOS: B. urceolaris e náuplios de copépodos, típicos de ambientes eutrofizados, apresentaram maiores densidades nos tratamentos eutrófico e hipereutrófico. Ainda, cianobactérias como Aphanothece sp. e Merismopedia sp. foram registradas nos tratamentos eutrófico e hipereutrófico, respectivamente. CONCLUSÕES: De maneira similar ao observado na natureza, o tratamento eutrófico apresentou maiores densidades de espécies do zooplâncton que se beneficiam do aumento na concentração de nutrientes. Respostas positivas ou negativas na dinâmica do zooplâncton fornecem uma ferramenta bioindicadora eficaz. Ainda, os resultados do presente estudo enfatizam a necessidade de implementar medidas reparadoras em ambientes aquáticos sujeitos a entradas constantes de nutrientes. Abstract in english AIMS: The present study evaluated the role that increased nutrient concentrations play on zooplankton community, by employing an experimental laboratory approach. METHODS: Experiments were conducted in the laboratory, where three trophic state conditions were simulated, namely, mesotrophic, eutrophi [...] c and hypereutrophic. Each treatment was replicated three times and individuals of Brachionus urceolaris (10 individuals), Hexarthra mira (5) (Rotifera), Latonopsis sp. (10), Moina minuta (10) (Cladocera) and Thermocyclops sp. (5) (Copepoda) were introduced to each replicate. On the first experiment day, and at 7-day intervals for a 14-day period (totaling three evaluations), all water content was collected from each container and filtered to determine the densities of each zooplankton species. Two-way MANOVA and one-way ANOVA designs were used to determine zooplankton density fluctuations among treatments and throughout the study period. Further, Generalized Linear Models (GLMs) were employed to assess how environmental factors affected zooplankton numbers. Phytoplankton composition was also determined in the beginning and in the end of the experiment. RESULTS: B. urceolaris and copepod nauplii, which are typical of eutrophic environments, showed higher densities on the eutrophic and hypereutrophic treatments. Furthermore, cyanobacteria such as Aphanothece sp. and Merismopedia sp. were recorded on the eutrophic and hypereutrophic treatments, respectively. CONCLUSIONS: Similarly to what is frequently observed in the wild, the eutrophic treatment showed higher densities of particular zooplankton species which are known to temporarily benefit from an increase in trophic concentrations. Positive or negative responses from zooplankton dynamics (but also phytoplankton species), provide an important bioindicator framework. Furthermore, results of the present study outline the need for implementing recovery measures on aquatic environments subject to constant nutrient inputs.

  16. Zooplankton associations and environmental factors in Ogunpa and Ona rivers, Nigeria

    Directory of Open Access Journals (Sweden)

    Gbemisola A. Akin-Oriola

    2003-06-01

    Full Text Available Zooplankton abundance, composition and environmental parameters were monitored in two tropical rivers over a twenty month period. The data was subjected to cluster, factor and correlation analysis to determine the grouping pattern of zooplankton and their relationship to environmental parameters. Environmental factors in Ogunpa and Ona rivers -included buffering capacity, trace metal ions, pH-temperature/ transparency- were primarily influenced by rainfall. The dominance of the Rotifera in both rivers was attributed to their short developmental rate and fish predation on larger zooplankton. Two groups of associations were identified in each river - a commonly occurring species group exhibiting strong homogenous correlation with environmental factors and a predominant group exhibiting weak correlation with environmental factors and whose abundance / composition may be defined by biotic factors.La abundancia, y composición del zooplancton, y parámetros ambientales fueron monitoreados en dos ríos tropicales durante un período de doce meses. Los datos fueron sometidos a análisis de agrupaciones, de factores y de correlación para determinar los patrones de agrupamiento del zooplancton y sus relaciones con parámetros ambientales. Los factores ambientales en los ríos Ogunpa y Ona, incluidos la capacidad tampón, iones metálicos traza, pH-temperatura/ transparencia, fueron influenciados principalmente por la lluvia. La dominancia de los Rotíferos en ambos ríos fue atribuida a su corta tasa de desarrollo y a la depredación del zooplancton grande por peces. Dos grupos de asociaciones fueron identificadas en cada río - la presencia de un grupo común de especies que exhiben una fuerte y homogénea correlación con factores ambientales y un grupo predominante que exhibe una débil correlación con factores ambientales y cuya abundancia / composición que podría estar definida por factores bióticos.

  17. Does the zooplankton prey availability limit the larval habitats of pike in the Baltic Sea?

    Science.gov (United States)

    Kallasvuo, Meri; Salonen, Maiju; Lappalainen, Antti

    2010-01-01

    The objectives of this study were to (1) investigate whether the availability of suitable zooplankton prey limits the distribution of the coastal larval areas of pike ( Esox lucius) in two archipelago areas of the northern Baltic Sea and (2) compare the availability of zooplankton prey in spring between different types of coastal littoral habitat. According to the results, reed belt habitats formed by Phragmites australis constitute hot spots for zooplankton prey in the coastal ecosystem. During the spring, reed-covered shores of the inner archipelago maintained more than 10 times higher densities of copepods and cladocerans, the preferred prey for larval pike, compared to the other studied shores. Temperature conditions were also most favourable in the reed belt habitat. Thus, the reed belts of the inner and middle archipelago were shown to form the best habitat for larval pike in the coastal area of the northern Baltic Sea, and this was also the only habitat where pike larvae were found. Our results suggest that the poor survival and recruitment of pike in the outer archipelago, however, cannot exclusively be explained by sub-optimal feeding conditions of the larvae. There are also other important factors, presumably connected to the exposure to the open sea, that affect the distribution of the pike larvae. Our results, however, highlight the importance of sheltered coastal reed belt shores as reproduction habitat for spring-spawning fish in the northern Baltic Sea. Further, this study disproves the assumption that the seaweed bladder wrack ( Fucus vesiculosus) forms a reproduction habitat for pike in the coastal area.

  18. Recovery after local extinction: factors affecting re-establishment of alpine lake zooplankton.

    Science.gov (United States)

    Knapp, Roland A; Sarnelle, Orlando

    2008-12-01

    The introduction of fishes into naturally fishless mountain lakes often results in the extirpation of large-bodied zooplankton species. The ability to predict whether or not particular species will recover following fish removal is critically important for the design and implementation of lake restoration efforts but is currently not possible because of a lack of information on what factors affect recovery. The objective of this study was to identify the factors influencing recovery probability in two large-bodied zooplankton species following fish removal. We predicted that (1) Daphnia melanica would have a higher probability of recovery than Hesperodiaptomus shoshone due to differences in reproductive mode (D. melanica is parthenogenetic, H. shoshone is obligately sexual), (2) recovery probability would be a decreasing function of fish residence time due to the negative relationship between fish residence time and size of the egg bank, and (3) recovery probability would be an increasing function of lake depth as a consequence of a positive relationship between lake depth and egg bank size. To test these predictions, we sampled contemporary zooplankton populations and collected paleolimnological data from 44 naturally fishless lakes that were stocked with trout for varying lengths of time before reverting to a fishless condition. D. melanica had a significantly higher probability of recovery than did H. shoshone (0.82 vs. 0.54, respectively). The probability of recovery for H. shoshone was also significantly influenced by lake depth, fish residence time, and elevation, but only elevation influenced the probability of recovery in D. melanica. These results are consistent with between-species differences in reproductive mode combined with the much greater longevity of diapausing eggs in D. melanica than in H. shoshone. Our data also suggest that H. shoshone will often fail to recover in lakes with fish residence times exceeding 50 years. PMID:19263883

  19. Migration from Packaging Materials

    Science.gov (United States)

    Meulenaer, B. De

    Various chemical compounds can be present in foodstuffs which may induce health problems in humans. The origin of these compounds can be very diverse. Mathematical modeling can sometimes be used to predict the concentration of these chemicals in the food. Particularly for compounds which are produced in the food during, e.g., processing and for compounds which migrate from a food contact material this technique can be very fruitful. For the former type of compounds, classical chemical kinetics can be applied. In this contribution, the modeling of the migration from polymeric food contact materials is considered. This migration phenomenon can be modeled mathematically since the physical processes which govern this process are very well studied and understood. Therefore, initially some of these fundamentals will be discussed in more detail.

  20. Quandary of migrated IUCD

    Directory of Open Access Journals (Sweden)

    Divya Pandey

    2014-08-01

    Full Text Available Intra Uterine Contraception Device (IUCD is the most widely used method of reversible contraception. However complications are known to occur with IUCD. Although uterine perforation is not very rare, but asymptomatic migration into urinary bladder and mesoappendix, is a very rare occurrence. We hereby report two such cases. Two cases of migrated IUCD into urinary bladder and mesoappendix is described here. Both case remained asymptomatic over years and diagnosed incidentally. But IUCD was retrieved in both by surgical means. Owing to possibility of potential complications and medico-legal concerns due to migrated IUCD, it needs to be removed even in asymptomatic cases. [Int J Reprod Contracept Obstet Gynecol 2014; 3(4.000: 1110-1112

  1. Does salinity change determine zooplankton variability in the saline Qarun Lake (Egypt)?

    Science.gov (United States)

    El-Shabrawy, Gamal M.; Anufriieva, Elena V.; Germoush, Mousa O.; Goher, Mohamed E.; Shadrin, Nickolai V.

    2015-11-01

    Zooplankton and 14 abiotic variables were studied during August 2011 at 10 stations in Lake Qarun, Egypt. Stations with the lowest salinity and highest nutrient concentrations and turbidity were close to the discharge of waters from the El-Bats and El-Wadi drainage systems. A total of 15 holozooplankton species were identified. The salinity in Lake Qarun increased and fluctuated since 1901: 12 g/L in 1901; 8.5 g/L in 1905; 12.0 g/L in 1922; 30.0 g/L in 1985; 38.7 g/L in 1994; 35.3 g/L in 2006, and 33.4 g/L in 2011. The mean concentration of nutrients (nitrate, nitrite and orthophosphate) gradually increased from 35, 0.16 and 0.38 µg/L, respectively, in 1953-1955 to 113, 16.4, and 30.26 µg/L in 2011. From 1999-2003 some decrease of species diversity occurred. Average total zooplankton density was 30 000 ind./m3 in 1974-1977; 356 125 ind./m3 in 1989; 534 000 ind./m3 in 1994-1995; from 965 000 to 1 452 000 ind./m3 in 2006, and 595 000 ind./m3 in 2011. A range of long-term summer salinity variability during the last decades was very similar to a range of salinity spatial variability in summer 2011. There is no significant correlation between zooplankton abundance and salinity in spatial and long-term changes. We conclude that salinity fluctuations since at least 1955 did not directly drive the changes of composition and abundance of zooplankton in the lake. A marine community had formed in the lake, and it continues to change. One of the main drivers of this change is a regular introduction and a pressure of alien species on the existent community. Eutrophication also plays an important role. The introduction of Mnemiopsis leidyi, first reported in 2014, may lead to a start of a new stage of the biotic changes in Lake Qarun, when eutrophication and the population dynamics of this ctenophore will be main drivers of the ecosystem change.

  2. Spring bloom dynamics and zooplankton biomass response on the US Northeast Continental Shelf

    Science.gov (United States)

    Friedland, Kevin D.; Leaf, Robert T.; Kane, Joe; Tommasi, Desiree; Asch, Rebecca G.; Rebuck, Nathan; Ji, Rubao; Large, Scott I.; Stock, Charles; Saba, Vincent S.

    2015-07-01

    The spring phytoplankton bloom on the US Northeast Continental Shelf is a feature of the ecosystem production cycle that varies annually in timing, spatial extent, and magnitude. To quantify this variability, we analyzed remotely-sensed ocean color data at two spatial scales, one based on ecologically defined sub-units of the ecosystem (production units) and the other on a regular grid (0.5°). Five units were defined: Gulf of Maine East and West, Georges Bank, and Middle Atlantic Bight North and South. The units averaged 47×103 km2 in size. The initiation and termination of the spring bloom were determined using change-point analysis with constraints on what was identified as a bloom based on climatological bloom patterns. A discrete spring bloom was detected in most years over much of the western Gulf of Maine production unit. However, bloom frequency declined in the eastern Gulf of Maine and transitioned to frequencies as low as 50% along the southern flank of the Georges Bank production unit. Detectable spring blooms were episodic in the Middle Atlantic Bight production units. In the western Gulf of Maine, bloom duration was inversely related to bloom start day; thus, early blooms tended to be longer lasting and larger magnitude blooms. We view this as a phenological mismatch between bloom timing and the "top-down" grazing pressure that terminates a bloom. Estimates of secondary production were available from plankton surveys that provided spring indices of zooplankton biovolume. Winter chlorophyll biomass had little effect on spring zooplankton biovolume, whereas spring chlorophyll biomass had mixed effects on biovolume. There was evidence of a "bottom up" response seen on Georges Bank where spring zooplankton biovolume was positively correlated with the concentration of chlorophyll. However, in the western Gulf of Maine, biovolume was uncorrelated with chlorophyll concentration, but was positively correlated with bloom start and negatively correlated with magnitude. This observation is consistent with both a "top-down" mechanism of control of the bloom and a "bottom-up" effect of bloom timing on zooplankton grazing. Our inability to form a consistent model of these relationships across adjacent systems underscores the need for further research.

  3. Horizontal distribution of Fukushima-derived radiocesium in zooplankton in the northwestern Pacific Ocean

    OpenAIRE

    Kitamura, M.; Kumamoto, Y.; Kawakami, H.; E.C. Cruz; K. Fujikura

    2013-01-01

    The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1). Fission products were emitted, falling over a broad range in the northern hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radiocesium in zooplankton and in seawater in the western North Pacific Ocean (500–2100 km from the FN...

  4. L-Lake zooplankton: L-Lake/Steel Creek Biological Monitoring Program, November 1985--December 1991

    International Nuclear Information System (INIS)

    The L- Lake Biological Monitoring Program was designed to meet environmental regulatory requirements associated with the restart of L-Reactor and address portions of Section 316(a) of the Clean Water Act, which requires an applicant for a discharge permit to provide scientific evidence that the discharge causes no significant impact on the indigenous ecosystem. The Department of Energy (DOE) must demonstrate that the discharge of L-Reactor affluent into L Lake will not inhibit the eventual establishment of a ''Balanced Biological Community'' (BBC) in at least 50% of the lake. This report details results of monitoring zooplankton populations in L-Lake

  5. Diel variations in zooplankton and their biochemical composition from Vengurla to Ratnagiri, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; KrishnaKumari, L.; Shrivastava, Y.

    for estimation of biochemical components. The samples were cleared of debris, washed with distilled water and dried at 60?C till constant weight. Proetins8, carbohydrates9 and lipids10 were estimated in triplicate. For diel variation study, the zooplankton... 326 349 325 93 139 70 00 46 29818 00 00 1163 93 488 00 4534 674 116 1884 00 325 232 232 SHORT COMMUNICATION 279 Average values (%) for proteins, carbohydrates and lipid for day and night samples are given in Fig.2. Protein ranged from 14.82 to 45...

  6. L-Lake zooplankton: L-Lake/Steel Creek Biological Monitoring Program, November 1985--December 1991

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, J.A. [Westinghouse Savannah River Co., Aiken, SC (United States); Bowen, M. [Normandeau Associates, Inc., New Ellenton, SC (United States)

    1992-03-01

    The L- Lake Biological Monitoring Program was designed to meet environmental regulatory requirements associated with the restart of L-Reactor and address portions of Section 316(a) of the Clean Water Act, which requires an applicant for a discharge permit to provide scientific evidence that the discharge causes no significant impact on the indigenous ecosystem. The Department of Energy (DOE) must demonstrate that the discharge of L-Reactor affluent into L Lake will not inhibit the eventual establishment of a ``Balanced Biological Community`` (BBC) in at least 50% of the lake. This report details results of monitoring zooplankton populations in L-Lake.

  7. Impact of climate change on zooplankton communities, seabird populations and arctic terrestrial ecosystem—A scenario

    Science.gov (United States)

    Stempniewicz, Lech; B?achowiak-Samo?yk, Katarzyna; W?s?awski, Jan M.

    2007-11-01

    Many arctic terrestrial ecosystems suffer from a permanent deficiency of nutrients. Marine birds that forage at sea and breed on land can transport organic matter from the sea to land, and thus help to initiate and sustain terrestrial ecosystems. This organic matter initiates the emergence of local tundra communities, increasing primary and secondary production and species diversity. Climate change will influence ocean circulation and the hydrologic regime, which will consequently lead to a restructuring of zooplankton communities between cold arctic waters, with a dominance of large zooplankton species, and Atlantic waters in which small species predominate. The dominance of large zooplankton favours plankton-eating seabirds, such as the little auk ( Alle alle), while the presence of small zooplankton redirects the food chain to plankton-eating fish, up through to fish-eating birds (e.g., guillemots Uria sp.). Thus, in regions where the two water masses compete for dominance, such as in the Barents Sea, plankton-eating birds should dominate the avifauna in cold periods and recess in warmer periods, when fish-eaters should prevail. Therefore under future anthropogenic climate scenarios, there could be serious consequences for the structure and functioning of the terrestrial part of arctic ecosystems, due in part to changes in the arctic marine avifauna. Large colonies of plankton-eating little auks are located on mild mountain slopes, usually a few kilometres from the shore, whereas colonies of fish-eating guillemots are situated on rocky cliffs at the coast. The impact of guillemots on the terrestrial ecosystems is therefore much smaller than for little auks because of the rapid washing-out to sea of the guano deposited on the seabird cliffs. These characteristics of seabird nesting sites dramatically limit the range of occurrence of ornithogenic soils, and the accompanying flora and fauna, to locations where talus-breeding species occur. As a result of climate warming favoring the increase of ichthyiofagous cliff-nesting seabirds, we can expect that large areas of ornithogenic tundra around the colonies of plankton-eating seabirds situated far from the sea may disappear, while areas of tundra in the vicinity of cliffs inhabited by fish-eating seabirds, with low total production and supporting few large herbivores, will likely increase, but only imperceptibly. This may lead to habitat fragmentation with negative consequences for populations of tundra-dependent birds and mammals, and the possibility of a substantial decrease in biodiversity of tundra plant and animal communities.

  8. Zooplankton communities fluctuations from 1995 to 2005 in the Bay of Villefranche-sur-Mer (Northern Ligurian Sea, France

    Directory of Open Access Journals (Sweden)

    P. Vandromme

    2010-12-01

    Full Text Available An integrated analysis of the pelagic ecosystems of the Ligurian Sea is performed combining time series of different zooplankton groups (small and large copepods, chaetognaths, appendicularians, pteropods, thaliaceans, decapods larvae, other crustaceans, other gelatinous and other zooplankton, chlorophyll-a and nutrients, seawater salinity, temperature and density and local weather at the Point B coastal station (Northern Ligurian Sea. From January 1995 to December 2005, a shift in most variables occurred ca. 2000. From 1995 to 2000 winters were wet and mild resulting in lower winter sea surface density. These years showed lower than average nutrients and zooplankton concentrations while phytoplankton biomass was higher. After 2000, winters were colder and dryer resulting in higher sea surface density. Nutrients and zooplankton showed higher concentrations while phytoplankton was lower than average. The ca. 2000 shift was observed for most zooplankton groups with a one year delay for certain groups. The observed patterns suggest that the pelagic ecosystem trophic state is mostly set by the winter forcing on the convection that upwells nutrients to the surface sustaining the spring bloom. However, low phytoplankton concentrations in higher nitrate and zooplankton conditions during the well mixed years suggest that phytoplankton is controlled by grazers. The proposed mechanisms of convection regimes hold for most of the time series, but specific years with contradicting patterns needed to be explained by other factors. The limitation of phytoplankton growth by the light availability in spring/summer was then proposed as a secondary driving force that can moderate or even reverse the winter forcing. Finally, the eleven years of observation did not reveal a clear link with the North Atlantic Oscillation, suggesting a more complex dynamics linking large scale climate to Ligurian Sea ecosystems or that the length of the plankton monitoring is not yet sufficient to detect those links.

  9. Unix Application Migration Guide

    CERN Document Server

    Microsoft. Redmond

    2003-01-01

    Drawing on the experience of Microsoft consultants working in the field, as well as external organizations that have migrated from UNIX to Microsoft® Windows®, this guide offers practical, prescriptive guidance on the issues you are likely to face when porting existing UNIX applications to the Windows operating system environment. Senior IT decision makers, network managers, and operations managers will get real-world guidance and best practices on planning and implementation issues to understand the different methods through which migration or co-existence can be accomplished. Also detailing

  10. [Migration, climate and health].

    Science.gov (United States)

    Tellier, Siri; Carballo, Manuel; Calballo, Manuel

    2009-10-26

    Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which environmental refugees find themselves and the consequences this may have. Finally, it points to the urgent need to reform health systems in both developing and developed countries to adapt to rapidly changing disease patterns and to become more responsive to them. PMID:19857400

  11. Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities

    Directory of Open Access Journals (Sweden)

    L. Patara

    2008-08-01

    Full Text Available This paper analyzes the relationship between deep sedimentary fluxes and ocean current vertical velocities in an offshore area of the Ionian Sea, the deepest basin of the Eastern Mediterranean Sea. Sediment trap data are collected at 500 m and 2800 m depth in two successive moorings covering the period September 1999–May 2001. A tight coupling is observed between the upper and deep traps and the estimated particle sinking rates are higher than 200 m day?1. The current vertical velocity field is computed from a high resolution Ocean General Circulation Model simulation and from the wind stress curl. Current vertical velocities are larger and more variable than Ekman vertical velocities, yet the general patterns are alike. Current vertical velocities are generally smaller than 1 m day?1: we therefore exclude a direct effect of downward velocities in determining high sedimentation rates. However, we find that upward velocities in the subsurface layers of the water column are positively correlated with deep particle fluxes. We thus hypothesize that upwelling would produce an increase in upper ocean nutrient levels – thus stimulating primary production and grazing – a few weeks before an enhanced vertical flux is found in the sediment traps. By analyzing the delayed effects of ocean vertical velocities on deep particle fluxes we envisage a spectrum of particle sinking speeds ranging from about 100 m day?1 to more than 200 m day?1. High particle sedimentation rates may be attained by means of rapidly sinking fecal pellets produced by gelatinous macro-zooplankton. Other sedimentation mechanisms, such as dust deposition, are also considered in explaining large pulses of deep particle fluxes. The fast sinking rates estimated in this study might be an evidence of the efficiency of the biological pump in sequestering organic carbon from the surface layers of the deep Eastern Mediterranean basins.

  12. Changes of species composition, formation of quantitative structure and peculiarities of development of proto- and meta zooplankton under the impact of ecological factors in Lake Drukshiai

    International Nuclear Information System (INIS)

    According to 1993-95 research data, water temperature was found to be the most significant factor influencing the structure of zooplankton as well as seasonal development changes. Because of great amount of heated water discharged from Ignalina NPP, determining an increase of the temperature in all water layers and disappearance of the thermal zone below 10 degrees of Centigrade in deep water layers in summer, the species diversity of zooplankton decreased more than twice if compared with 1979-86. Cold-steno thermal species were the first to disappear. At the same time, warm-requiring and eurithermal species predominated. Natural seasonal rise of temperature (till 26.5 degrees of Centigrade) stimulated the development of some groups of meta zooplankton (Cladocera and Copepod a). The abundance of most species of Rotator ia decreased when the water temperature was over 15 degrees of Centigrade. The heated water discharged from Ignalina NPP caused structural changes of meta zooplankton, decrease of its biomass, decrease of the amount and biomass of proto zooplankton in this area. Because of heated water impact, the highest mortality of proto zooplankton was observed in summer. One maximum of quantitative development was characteristic of seasonal dynamics of zooplankton in Lake Drukshiai, while in water basins with natural thermal regime there are 2 seasonal maxima. Dependence of proto zooplankton on phytoplankton nd on Copepod a as well as dependence of meta zooplankton on phytoplankton were investigated. Data on spatial distribution of zooplankton in Lake Drukshiai indicate the eutrophication process in the southwestern part of the lake (because of increase of biogen s concentration). (author)

  13. Concerning calculation methods and limitations of proxy-estimates of Proteins, Carbohydrates and Lipids in crustacean zooplankton from CHN analyses

    Directory of Open Access Journals (Sweden)

    Richard A. VOLLENWEIDER

    2000-08-01

    Full Text Available The present comments resulted from a discussion I had with Dr. Riccardi about the validity of proxy estimates of protein, carbohydrate, and lipid in various zooplankton species of Northern Italian lakes (Riccardi & Mangoni 1999. For these estimates the authors used a calculation method proposed by Gnaiger & Bitterlich (1984; below referred to as G&B. The reason why I questioned the application of the unmodified G&B model to zooplankton was that carbohydrate in crustaceans is mostly present in form of chitin. The argumentation grow rapidly beyond a simple dispute about modes of calculation, leading to some more principle considerations about the limits of proxy estimates.

  14. Zooplankton as an environmental monitoring tool in the area under Almirante Alvaro Alberto nuclear power plant influence

    International Nuclear Information System (INIS)

    Available as short communication only. Angra nuclear power plant refrigeration systems uses sea water collected in Itaorna and discharged in Piraquara de Fora, with an increase in temperature. Besides this, chlorine is added to avoid fouling in the circulation system. Zooplankton, small and generally microscope organism is very sensible to environmental changes. This work describes the methodology to evaluate the influence of Angra nuclear power plant liquid effluents in zooplankton organisms describing results and verifying impacts in this area. (author). 4 refs, 4 figs

  15. The vertical transportation handbook

    CERN Document Server

    Strakosch, George R

    2010-01-01

    This new edition of a one-of-a-kind handbook provides an essential updating to keep the book current with technology and practice.  New coverage of topics such as machine-room-less systems and current operation and control procedures, ensures that this revision maintains its standing as the premier general reference on vertical transportation.  A team of new contributors has been assembled to shepherd the book into this new edition and provide the expertise to keep it up to date in future editions.  A new copublishing partnership with Elevator World Magazine ensures that the quality of the rev

  16. 'Endurance' Untouched (vertical)

    Science.gov (United States)

    2004-01-01

    This navigation camera mosaic, created from images taken by NASA's Mars Exploration Rover Opportunity on sols 115 and 116 (May 21 and 22, 2004) provides a dramatic view of 'Endurance Crater.' The rover engineering team carefully plotted the safest path into the football field-sized crater, eventually easing the rover down the slopes around sol 130 (June 12, 2004). To the upper left of the crater sits the rover's protective heatshield, which sheltered Opportunity as it passed through the martian atmosphere. The 360-degree view is presented in a vertical projection, with geometric and radiometric seam correction.

  17. Vertical Protocol Composition

    DEFF Research Database (Denmark)

    Groß, Thomas; Mödersheim, Sebastian Alexander

    2011-01-01

    The security of key exchange and secure channel protocols, such as TLS, has been studied intensively. However, only few works have considered what happens when the established keys are actually used—to run some protocol securely over the established “channel”. We call this a vertical protocol composition, and it is truly commonplace in today’s communication with the diversity of VPNs and secure browser sessions. In fact, it is normal that we have several layers of secure channels: For instance, on top of a VPN-connection, a browser may establish another secure channel (possibly with a different end point). Even using the same protocol several times in such a stack of channels is not unusual: An application may very well establish another TLS channel over an established one. We call this selfcomposition. In fact, there is nothing that tells us that all these compositions are sound, i.e., that the combination cannot introduce attacks that the individual protocols in isolation do not have. In this work, we provea composability result in the symbolic model that allows for arbitrary vertical composition (including self-composition). It holds for protocols from any suite of channel and application protocols that fulfills a number of sufficient preconditions. These preconditions are satisfied for many practically relevant protocols such as TLS.

  18. From migration flows to migration systems: the case of Ukraine

    OpenAIRE

    Pyatkovska, Oksana

    2013-01-01

    The author of the article singles out countriesparticipants of migration systems with Ukraine as a source country and, by ranking them according to the selected indicators, makes the analysis of the formation and effectiveness of migration systems. As the result, an attempt to predict possible destination countries of future migration outflows from Ukraine is made.

  19. The International Organization for Migration in Global Migration Governance

    OpenAIRE

    Poulsen, Sofie Havn; Andersen, Lise

    2011-01-01

    This project focuses on the IOM, the notion of global governance of migration and the interaction between these two. The point of departure has been an attempt to grasp the current global approach to migration and comprehend whether, or to what degree, there is governance of migration issues taking place at a global level.

  20. International Migration of Couples

    DEFF Research Database (Denmark)

    Munk, Martin D.; Junge, Martin

    2015-01-01

    We analyze emigration and return decisions of Danish couples. Our main questions are how emigration and return migration decisions depend on education, earnings, and the number and age of children. We use register data on full population from 1982 to 2006, focusing on opposite-gender couples in which the female is aged 23 to 37, and the male 25 to 39. We find that power couples in which both are highly educated are most likely to emigrate, but also most likely to return. Couples in which only the male is highly educated are more than twice as likely to emigrate as if only the female is highly edu-cated. Couples in which neither partner is highly educated are least likely to emigrate, but also have lowest return migration rates. This suggests that migration as brain circu-lation is most pronounced among the highly-educated. The probability of emigration is increasing in male earnings, but does not depend much on female earnings. Having children reduces the likelihood of emigration and the more so the older children are. Surprisingly, the return rates do not depend much on the number of children. Overall, our findings suggest that family migration patterns are still surprisingly traditional, re-sponding more to the male's job opportunities and education.

  1. Selective Migration--Again.

    Science.gov (United States)

    Kamin, Leon J.

    1980-01-01

    Wolff has recently reinterpreted the data of Lee to indicate that Black migration from the south to Philadelphia had been selective in an IQ-relevant manner. However, Wolff's deduction from Lee's data is shown to depend entirely upon an assumption about cumulative IQ deficit in southern Black children. (Author/CTM)

  2. Practical Data Migration

    CERN Document Server

    Morris, Johny

    2012-01-01

    This book is for executives and practitioners tasked with the movement of data from old systems to a new repository. It uses a series of steps guaranteed to get the reader from an empty new system to one that is working and backed by the user population. Using this proven methodology will vastly increase the chances of a successful migration.

  3. Migration pathways in soils

    International Nuclear Information System (INIS)

    This study looked at diffusive migration through three types of deformation; the projectile pathways, hydraulic fractures of the sediments and faults, and was divided into three experimental areas: autoradiography, the determination of diffusion coefficients and electron microscopy of model projectile pathways in clay. For the autoradiography, unstressed samples were exposed to two separate isotopes, Pm-147 (a possible model for Am behaviour) and the poorly sorbed iodide-125. The results indicated that there was no enhanced migration through deformed kaolin samples nor through fractured Great Meteor East (GME) sediment, although some was evident through the projectile pathways in GME and possibly through the GME sheared samples. The scanning electron microscopy of projectile pathways in clay showed that emplacement of a projectile appeared to have no effect on the orientation of particles at distances greater than two projectile radii from the centre of a projectile pathway. It showed that the particles were not simply aligned with the direction of motion of the projectile but that, the closer to the surface of a particular pathway, the closer the particles lay to their original orientation. This finding was of interest from two points of view: i) the ease of migration of a pollutant along the pathway, and ii) possible mechanisms of hole closure. It was concluded that, provided that there is no advective migration, the transport of radionuclides through sediments containing these defects would not be significantly more rapid than in undeformed sediments. (author)

  4. Brain Migration Revisited

    Science.gov (United States)

    Vinokur, Annie

    2006-01-01

    The "brain drain/brain gain" debate has been going on for the past 40 years, with irresolvable theoretical disputes and unenforceable policy recommendations that economists commonly ascribe to the lack of reliable empirical data. The recent report of the World Bank, "International migration, remittances and the brain drain", documents the…

  5. Migration and Africa

    DEFF Research Database (Denmark)

    Zoppi, Marco

    2014-01-01

    European powers imposed the nation-state on Africa through colonialism. But even after African independencies, mainstream discourses and government policies have amplified the idea that sedentariness and the state are the only acceptable mode of modernity. Migration is portrayed as a menace to the societies where the migrants wish to settle

  6. Religion, migration og integration

    DEFF Research Database (Denmark)

    Borup, Jørn

    2010-01-01

    Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i integrationsspørgsmål.

  7. Radionuclide migration in groundwater

    International Nuclear Information System (INIS)

    The migration rates and mechanisms of a large suite of radionuclides in groundwater created by the disposal of low-level aqueous effluents from the Hanford N-Reactor are being characterized. These studies are developing information which can be applied to understanding and predicting the movement of radionuclides in shallow-land burial sites which may become saturated with groundwater. The movement of the various radionuclides in groundwater at the N-Reactor disposal site is being investigated as a function of their physicochemical forms. Those radionuclides most readily migrating include tritium and anionic species of 131133I, 60Co, 103106Ru, 122124125Sb, /sup 99m,99/Tc, and 99Mo. Also migrating are traces of 238239240Pu in an oxidized (V or VI) anionic form(s). Various parameters affecting the physicochemical speciation of the radionuclides, including the major and trace ions, organic constitutents, colloidal materials, and soil chemistry are being characterized to determine their relative roles in the migration processes. the data generated in this study will be extremely valuable in formulating guidelines for the operation of existing low-level waste disposal sites, in determining what long-term surveillance and maintenance needs will be required, and in determining essential requirements for remedial action. 4 tables

  8. Fall armyworm migration patterns.

    Science.gov (United States)

    Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), infestations in most of North America arise from annual migrations of populations that overwinter in southern Texas and Florida. Cytochrome Oxidase I haplotype profiles within the fall armyworm corn-strain, the subgroup tha...

  9. Migration measurement of acetabular components in cementless total hip arthroplasty

    International Nuclear Information System (INIS)

    Migration measurements of acetabular components using a special computer aided method (EBRA = abbrevation for the German term ''Ein-Bild-Roentgenanalyse'') were performed to evaluate early results of the implants and predict aseptic loosening. Methods: Standard ap-radiographs of the pelvis were marked, specific points were digitised. Simulating the spatial situation the programme computes lengitudinal and vertical migration of the cup. 74 acetabular components in 71 patients could be studied by migration measurements. Results: 14 patients showed migration of more than 1 mm, which is the confidence limit of this method. Each of these patients showed diverse reasons for the migration, i.e. osteoporosis of the acetabular bone stock or problems concerning the surgical technique which means malposition of the cup or insufficient reaming of the bone. There were some patients with severe congenital dysplasia of the hip and in some cases the inclination angle of the cup was too great. Conclusion: The technique applied for measuring migration of acetabular components can be useful for evaluating early instability of the implant and can be helpful in detecting problems concerning the surgical technique. (orig.)

  10. Estimates of potential radionuclide migration at the Bullion site

    International Nuclear Information System (INIS)

    The Bullion site in Area 20 of the Nevada Test Site has been selected for an intensive study of the hydrologic consequences of underground testing, including subsequent radionuclide migration. The bulk of the chimney and cavity lie in zeolitized tuffs of low hydraulic conductivity, while the base of the cavity may extend downward into more conductive rhyolite flows. A mathematical analog to the Bullion setting is used here to estimate expected radionuclide migration rates and concentrations. Because of a lack of hydrologic data at the site, two contrasting scenarios are considered. The first is downward-transport, in which downward hydraulic gradients flush chimney contents into the conductive underlying units, enhancing migration. The other is upward-transport, in which upward gradients tend to drive chimney contents into the low-conductivity zeolitized tuffs, discouraging migration. In the downward-transport scenario, radionuclide travel times and concentrations are predicted to be similar to those encountered at Cheshire, requiring approximately 10 years to reach a proposed well 300 m downgradient. The upward transport scenario yields predicted travel times on the order of 2,000 years to the downgradient well. The most likely scenario is a combination of these results, with vertical movement playing a limited role. Radionuclides injected directly into the rhyolites should migrate laterally very quickly, with travel times as in the downward-transport scenario. Those in the zeolitized tuff-walled portion of the chimney should migrate extremely slowly, as in the upward-transport scenario

  11. Oceanic migration behaviour of tropical Pacific eels from Vanuatu

    DEFF Research Database (Denmark)

    Schabetsberger, R; Økland, F

    2013-01-01

    Information on oceanic migrations and spawning areas of tropical Pacific freshwater eels (genus Anguilla) is very limited. Lake Letas and its single outflowing river, Mbe Solomul on Gaua Island, Vanuatu, were surveyed for large migrating individuals. Twenty-four Anguilla marmorata (87 to 142 cm), 39 A. megastoma (50 to 131 cm), and 3 A. obscura (119 to 126 cm) were caught. Seven individuals were tagged with pop-up satellite transmitters and released offshore. One A. marmorata migrated 843 km towards the South Equatorial Current. The tag surfaced only 330 km from the point where the smallest leptocephalus has been captured so far. Tags on A. megastoma and A. obscura popped up within the archipelago. All 3 species exhibited pronounced diel vertical migrations. Eels descended from around 200 m nighttime depth, to 320 (A. obscura), 650 (A. marmorata), and 750 m (A. megastoma) during the day. A clear impact of the lunar cycle on the upper limit of migration depths was found in A. marmorata (full moon: 230 m, new moon: 170 m). These behaviours may be explained as a trade-off between predator avoidance and the necessity to maintain a sufficiently high metabolism for migration.

  12. Radionuclide migration studies in soil

    International Nuclear Information System (INIS)

    In this work a brief description about retention and migration parameters of radionuclides in soil, including main methods to determine the distribution coefficient (K) are given. Some of several factors that can act on the migration are also mentioned. (author)

  13. Chemical Response of the Toxic Dinoflagellate Karenia mikimotoi Against Grazing by Three Species of Zooplankton.

    Science.gov (United States)

    Dang, Lin-Xi; Li, Yue; Liu, Fei; Zhang, Yong; Yang, Wei-Dong; Li, Hong-Ye; Liu, Jie-Sheng

    2015-01-01

    We investigated the toxicity of Karenia mikimotoi toward three model grazers, the cladoceran Moina mongolica, the copepod Pseudodiaptomus annandalei, and the crustacean Artemia salina, and explored its chemical response upon zooplankton grazing. An induction experiment, where K. mikimotoi was exposed to grazers or waterborne cues from the mixed cultures revealed that K. mikimotoi might be toxic or nutritionally inadequate toward the three grazers. In general, direct exposure to the three grazers induced the production of hemolytic toxins and the synthesis of eicosapentaenoic acid (EPA). Both EPA and the hemolytic toxins from K. mikimotoi decreased the survival rate of the three grazers. In addition, the survival rates of M. mongolica, P. annandalei, and A. salina in the presence of induced K. mikimotoi that had previously been exposed to a certain grazer were lower than their counterparts caused by fresh K. mikimotoi, suggesting that exposure to some grazers might increase the toxicity of K. mikimotoi. The chemical response and associated increased resistance to further grazing suggested that K. mikimotoi could produce deterrents to protect against grazing by zooplankton and that the substances responsible might be hemolytic toxins and EPA. PMID:25523905

  14. Survey of selenium in water, zooplankton and fish in Lake Koocanusa, British Columbia, 2008

    International Nuclear Information System (INIS)

    Coal mining within the Elk River basin has resulted in elevated levels of water-borne selenium. The purpose of this study was to determine concentrations of metals, specifically selenium, in 3 specific ecosystem compartments, notably water, zooplankton and fish tissue, within Lake Koocanusa, upstream and downstream of the Elk River confluence. The study was designed to determine the risks to the aquatic environment, based on a comparison with current aquatic life water quality guidelines and tissue-based thresholds. The study also determined whether the data corroborates historical data for Lake Koocanusa. The changes in concentrations among the sites were measured. Five sub-samples of water and zooplankton were sampled at each of 3 locations along the reservoir, and 2 species of fish (kokanee and peamouth chub), were also sampled at similar locations. Egg and muscle tissue were analyzed, as well as whole body tissue in order to compare data with the 2002 survey. This paper outlined the methods used and results of the study. Results and recommendations were also presented. The author recommended that a survey similar to this one be conducted in 2011 in order to evaluate trends in the downstream lentic environment, but with consideration for several additions and modifications. 32 refs., 5 tabs., 12 figs., 13 appendices.

  15. ZOOPLANCTON EN LA LARVICULTURA DE PECES NEOTROPICALES / ZOOPLANKTON IN LARVICULTURE OF NEOTROPICAL FISHES

    Scientific Electronic Library Online (English)

    Martha, Prieto G; Victor, Atencio G.

    2008-05-01

    Full Text Available La larvicultura de peces neotropicales altriciales presenta limitaciones para el manejo de la primera alimentación dado el pobre desarrollo del tracto digestivo y capacidad natatoria. La alimentación de la larva debe considerar el tamaño, densidad y calidad de la presa ofrecida. Este documento revis [...] a a la luz de recientes trabajos la incidencia del zooplancton en la larvicultura de peces, aborda la importancia de la larvicultura en el proceso piscícola, la importancia del zooplancton como alimento y las alternativas en el manejo de cladóceros, copépodos y rotíferos para la alimentación de larvas de especies neotropicales. Abstract in english Because of the poor development of digestive system and swimming capability of young fish, larviculture of altricial neotropical fish presents for the management of the initial feeding. The feeding of the larvae must consider the size, density and quality of the prey offered. This document reviews t [...] he incidence of zooplankton in fish larvicultura, approaches the importance of larviculture in fish rearing, the importance of zooplankton as prey, and alternatives in the handling of cladocerans, copepods and rotifers for the feeding of larvae of neotropical fishes.

  16. Effect of temperature and body size on electron transport system activity in freshwater zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.

    1978-04-01

    Electron transport system (ETS) activity in Mysis relicta, Limnocalanus macrurus, and surface zooplankton was measured by following the rate of reduction of cytochrome c in the presence of NADH, succinate or NADPH. The steady-state kinetics indicate that NADPH is oxidized by a different ETS from NADH and succinate, and more than one system amy exist for the oxidation of NADH and succinate in surface zooplankton. The NADPH requiring ETS which, because of its higher K/sub m/, presumably does not reduce cytochrome c in vivo, is probably equivalent to the microsomal NADPH requiring ETS from vertebrates and insects used in the detoxification of organic compounds. ETS activity is affected by both environmental temperature and size of the organism, with environmental temperature affecting both the total activity of the enthalpy of activation of the system. Larger organisms have a lower activity per unit weight compared with smaller animals. Because the effects of temperature and size are roughly similar for NADPH oxidation and NADH or succinate oxidation, the ratio of NADPH to either NADH or succinate oxidation may be a useful indicator of exposure to toxic organic compounds.

  17. Spatiotemporal dynamics in a reaction–diffusion toxic-phytoplankton–zooplankton model

    International Nuclear Information System (INIS)

    In this paper, we investigate the complex dynamics of a spatial toxic-phytoplankton–zooplankton model with Holling type-II functional response. Through a detailed analytical study of the reaction–diffusion model, we obtain some conditions for local and global stability and for diffusive instability with zero-flux boundary conditions of a positive equilibrium. On the basis of these results, we present the evolutionary processes of pattern formation that involve organism distribution and the interaction of a spatially distributed population with local diffusion. Then, novel numerical evidence of the time evolution of patterns controlled by diffusion and environmental carrying capability in the model are presented, and it is found that the model dynamics exhibits complex pattern replication. Additional studies reveal that pattern formation in the spatially extended model depends on the choice of the initial conditions. These results indicate that the interaction between toxin-producing phytoplankton and zooplankton in marine environments may be partly driven by the forces of diffusion or the environmental carrying capability. (paper)

  18. CHARACTERISTICS OF MIGRATION IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Daniela D?N?CIC?

    2010-06-01

    Full Text Available The aim of this research is to study the patterns of migration in Romania. Labor migration in Romania has seen major growth after 1989. Permanent migration rapidly increased in the early years after the revolution, decreasing rapidly thereafter, due to difficulties of obtaining long term residence and work permit in the host countries. However, temporary migration has been found to evolve very dynamically, requiring economic analysis of potential externalities, whether positive or the negative of this phenomenon.

  19. Solar UVB-induced DNA damage and photoenzymatic DNA repair in antarctic zooplankton

    International Nuclear Information System (INIS)

    The detrimental effects of elevated intensities of mid-UV radiation (UVB), a result of stratospheric ozone depletion during the austral spring, on the primary producers of the Antarctic marine ecosystem have been well documented. Here we report that natural populations of Antarctic zooplankton also sustain significant DNA damage [measured as cyclobutane pyrimidine dimers (CPDs)] during periods of increased UVB flux. This is the first direct evidence that increased solar UVB may result in damage to marine organisms other than primary producers in Antarctica. The extent of DNA damage in pelagic icefish eggs correlated with daily incident UVB irradiance, reflecting the difference between acquisition and repair of CPDs. Patterns of DNA damage in fish larvae did not correlated with daily UVB flux, possibly due to different depth distributions and/or different capacities for DNA repair. Clearance of CPDs by Antarctic fish and krill was mediated primarily by the photoenzymatic repair system. Although repair rates were large for all species evaluated, they were apparently inadequate to prevent the transient accumulation of substantial CPD burdens. The capacity for DNA repair in Antarctic organisms was highest in those species whose early life history stages occupy the water column during periods of ozone depletion (austral spring) and lowest in fish species whose eggs and larvae are abundant during winter. Although the potential reduction in fitness of Antarctic zooplankton rtion in fitness of Antarctic zooplankton resulting from DNA damage is unknown, we suggest that increased solar UV may reduce recruitment and adversely affect trophic transfer of productivity by affecting heterotrophic species as well as primary producers. 54 refs., 4 figs., 2 tabsThe detrimental effects of elevated intensities of mid-UV radiation (UVB), a result of stratospheric ozone depletion during the austral spring, on the primary producers of the Antarctic marine ecosystem have been well documented. Here we report that natural populations of Antarctic zooplankton also sustain significant DNA damage [measured as cyclobutane pyrimidine dimers (CPDs)] during periods of increased UVB flux. This is the first direct evidence that increased solar UVB may result in damage to marine organisms other than primary producers in Antarctica. The extent of DNA damage in pelagic icefish eggs correlated with daily incident UVB irradiance, reflecting the difference between acquisition and repair of CPDs. Patterns of DNA damage in fish larvae did not correlated with daily UVB flux, possibly due to different depth distributions and/or different capacities for DNA repair. Clearance of CPDs by Antarctic fish and krill was mediated primarily by the photoenzymatic repair system. Although repair rates were large for all species evaluated, they were apparently inadequate to prevent the transient accumulation of substantial CPD burdens. The capacity for DNA repair in Antarctic organisms was highest in those species whose early life history stages occupy the water column during periods of ozone depletion (austral spring) and lowest in fish species whose eggs and larvae are abundant during winter. Although the potential reduction in fitness of Antarctic zooplankton

  20. Cyanobacteria bloom: selective filter for zooplankton? / Floração de cianobactéria: filtro seletivo para zooplâncton?

    Scientific Electronic Library Online (English)

    NAST, Mello; PM, Maia-Barbosa.

    2015-03-01

    Full Text Available O reservatório de Ibirité é um ambiente urbano, eutrófico com periódicas ocorrências de florações de cianobactérias. O padrão de mistura deste reservatório é monomítico quente, permanecendo estratificado a maior parte do ano, circulando na estação seca (inverno). Durante o ciclo hidrológico de outub [...] ro/07 a outubro/08, ocorreram quatro cenários com condições ambientais distintas, que influenciaram na estruturação da comunidade zooplanctônica, conforme observado em estudo prévio. As mudanças na estrutura da comunidade zooplanctônica entre os cenários foram estudadas objetivando analisar a estabilidade e persistência desta comunidade. O coeficiente de correlação de Spearman foi utilizado para medir a estabilidade; a persistência foi considerada por meio de uma análise de agrupamento; e as mudanças na composição da comunidade foram estimadas através do índice de diversidade ? temporal. A comunidade foi estável, considerando os padrões de distribuição da abundância, somente na transição entre os cenários 1 e 2 (n=30; r= 0,71; p=0,00001), nos quais não foram observadas florações de cianobactérias. A persistência do zooplâncton entre os cenários foi baixa, apresentando composições de espécies distintas. As maiores variações na composição das espécies, estimadas através dos valores de diversidade ? temporal, foram nas transições entre os cenários 3-0 (1,45) e 0-1 (1,05), e o menor valor na transição entre os cenários 1-2 (0,57). Os resultados do presente trabalho sugerem que as florações de cianobactérias no reservatório de Ibirité estariam funcionando como “filtros seletivos”, ou seja, distúrbios com capacidade suficiente para alterar a estrutura da comunidade zooplanctônica. Abstract in english The Ibirité reservoir is an urban and eutrophic environment, with regular occurrences of cyanobacteria blooms. The reservoir is warm monomict and remains stratified most of the year, circulating in the dry season (winter). During the hydrological cycle of October/07 to October/08 there were four sce [...] narios with different environmental conditions, which influenced the structure of the zooplankton community, as confirmed in a previous study. Changes in the zooplankton community structure between the scenarios were studied, aiming at analyzing the stability and persistence of this community. The Spearman’s coefficient of correlation was used to measure the stability; the persistence was evaluated through a cluster analysis and changes in community composition were estimated by the "temporal" ? diversity index. Considering the distribution patterns of abundance, the community was stable only in the transition between scenarios 1 and 2 (n = 30, r = 0.71, p = 0.00001), when there were no cyanobacteria blooms. The persistence of zooplankton between the scenarios was low, showing a distinct species composition for each scenario. The highest variations in species composition, observed by the values of temporal ? diversity index, were the transitions between scenarios 3-0 (1.45) and 0-1 (1.05), and the lowest variations occurred in the transition between scenarios 1-2 (0.57). The results suggest that the cyanobacteria blooms at Ibirité reservoir are be acting as "selective filters", and are, thus, disturbances with sufficient ability to change the structure of the zooplankton community. Keywords Urban Reservoir, zooplankton, bloom of cyanobacteria, stability, persistence.

  1. FACTORS AFFECTING INTERNATIONAL LABOR MIGRATION

    Directory of Open Access Journals (Sweden)

    ?.?. ???????

    2012-03-01

    Full Text Available  The article reviews the evolution of the main theories that explain the labor migration system impacts on international labor migration are shown. Particular attention is paid to the analysis of external labor migration factors in Ukraine based on the use of the basic tenets of the "push and pull factors" theory.

  2. Knowledge Vertices in XUNL

    Scientific Electronic Library Online (English)

    Ronaldo, Martins.

    2012-06-01

    Full Text Available This paper addresses some lexical issues in the development of XUNL - a knowledge representation language descendent from and alternative to the Universal Networking Language (UNL). We present the current structure and the role of Universal Words (UW) in UNL and claim that the syntax and the semanti [...] cs of UWs demand a thorough revision in order to accomplish the requirements of language, culture and human independency. We draw some guidelines for XUNL and argue that its vertices should be represented by Arabic numerals; should be equivalent to sets of synonyms; should consist of generative lexical roots; should correspond to the elementary particles of meaning; and should not bear any non-relational meaning.

  3. Zooplankton standing and diversity in the Gulf of Kachchh with special reference to larvae of decapoda and pisces

    Digital Repository Service at National Institute of Oceanography (India)

    Paulinose, V.T.; Devi, C.B.L.; Nair, V.R.; Ramaiah, Neelam; Gajbhiye, S.N.

    rich in zooplankton standing stock showing a variation of 0.59 to 185.50 ml/10 m sup(3). The maximum biomass was at st 5-112.6 ml/100 m sup(3) in monsoon; population maximum were 942 no/100 m sup(3) during monsoon, 196 no/100 m sup(3) in postmonsoon...

  4. Zooplankton biomass and abundance of Antarctic krill Euphausia superba DANA in Indian Ocean sector of the southern ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Parulekar, A.H.

    considerable component of biomass and together with eggs and larvae represented over 60% (n = 39) of mean total zooplankton-biomass in the coastal ice region. The values for population density and biomass of adult-size krill varied between 0 to 4320 individuals...

  5. Trophic structure and levels of selected metals in the zooplankton community of Thane-Bassein Creek, Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Krishnamurti, A.J; Gajbhiye, S

    -83% to total zooplankton population. Decapods were relatively more in the outer (av. 11%) as compared to interior zone (av. 7%). Population density of carnivores were 2-4 times more in the polluted interior segment. Among the different metals studied Cu and Zn...

  6. Observations on phytoplankton pigments, zooplankton and physico-chemical parameters in surface waters from southern Indian Ocean and Antarctic region

    Digital Repository Service at National Institute of Oceanography (India)

    JiyalalRam, M.; Goswami, S.C

    and phaeopigments. Copepods, euphausiids, decapods, polychaetes and chaetognaths were the major constituents of zooplankton community. The salinity values varied from 34.06 to 36.14 x 10/3. Temperature fluctuations of the seawater were pronounced (-0.5 to 29.5?C...

  7. Restoring lakes by using artificial plant beds: habitat selection of zooplankton in a clear and a turbid shallow lake

    DEFF Research Database (Denmark)

    Schou, Majbritt Overgård; Risholt, Casper

    2009-01-01

    1. Return of large-bodied zooplankton populations is of key importance for creating a shift from a turbid to a clear-water state in shallow lakes after a nutrient loading reduction. In temperate lakes, recovery is promoted by submerged macrophytes which function as a daytime refuge for large zooplankton. However, recovery of macrophytes is often delayed and use of artificial plant beds (APB) has been suggested as a tool to enhance zooplankton refuges, thereby reinforcing the shift to a clear-water state and, eventually, colonisation of natural plants. 2. To further evaluate the potential of APB in lake restoration, we followed the day–night habitat choices of zooplankton throughout summer in a clear and a turbid lake. Observations were made in the pelagic and littoral zones and in APB in the littoral representing three different plant densities (coverage 0%, 40% and 80%). 3. In the clear lake, the zooplankton (primarily Daphnia) were mainly found in the pelagic area in spring, but from mid-May they were particularly abundant in the APB and almost exclusively so in mid-June and July, where they appeared in extremely high densities during day (up to 2600 ind. L?1). During night Daphnia densities were overall more equally distributed between the five habitats. Ceriodaphnia was proportionally more abundant in the APB during most of the season. Cyclopoids were more abundant in the high APB during day but were equally distributed between the five habitats during night. 4. In the turbid lake, however, no clear aggregation was observed in the APB for either of the pelagic genera (Daphnia and Bosmina). This may reflect a higher refuge effect in the open water due to the higher turbidity, reduced ability to orient to plant beds and a significantly higher fish density (mainly of roach, Rutilus rutilus, and perch, Perca fluviatilis) in the plant beds than in the clear lake. Chydorus was found in much higher proportions among the plants, while cyclopoids, particularly the pelagic Cyclops vicinus, dominated in the pelagic during day and in the pelagic and high density plants during night. 5. Our results suggest that water clarity is decisive for the habitat choice of large-bodied zooplankton and that introduction of APB as a restoration measure to enhance zooplankton survival is only a useful tool when water clarity increases following loading reduction. Our results indicate that dense APB will be the most efficient.

  8. Lake Roosevelt Fisheries Evaluation Program, Part B; Limnology, Primary Production, and Zooplankton in Lake Roosevelt, Washington, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Shields, John; Spotts, Jim; Underwood, Keith

    2002-11-01

    The Lake Roosevelt Fisheries Evaluation Program is the result of a merger between two projects, the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 to continue work historically completed under the separate projects, and is now referred to as the Lake Roosevelt Fisheries Evaluation Program. The 1998 Annual Report, Part B. Limnology, Primary Production, and Zooplankton in Lake Roosevelt, Washington examined the limnology, primary production, and zooplankton at eleven locations throughout the reservoir. The 1998 research protocol required a continuation of the more complete examination of limnological parameters in Lake Roosevelt that began in 1997. Phytoplankton and periphyton speciation, phytoplankton and periphyton chlorophyll a analysis, complete zooplankton biomass analysis by taxonomic group, and an increased number of limnologic parameters (TDG, TDS, etc.) were examined and compared with 1997 results. Total dissolved gas levels were greatly reduced in 1998, compared with 1997, likely resulting from the relatively normal water year experienced in 1998. Mean water temperatures were similar to what was observed in past years, with a maximum of 22.7 C and a minimum of 2.6 C. Oxygen concentrations were also relatively normal, with a maximum of 16.6 mg/L, and a minimum of 0.9 mg/L. Phytoplankton in Lake Roosevelt was primarily composed of microplankton (29.6%), Cryptophyceae (21.7%), and Bacillriophyceae (17.0 %). Mean total phytoplankton chlorophyll a maximum concentration occurred in May (3.53 mg/m{sup 3}), and the minimum in January (0.39 mg/m{sup 3}). Phytoplankton chlorophyll a concentrations appear to be influenced by hydro-operations and temperature. Trophic status as indicated by phytoplankton chlorophyll a concentrations place Lake Roosevelt in the oligomesotrophic range. Periphyton colonization rates and biovolume were significantly greater at a depth of 1.5 m (5 ft) when compared with a 4.6 m (15 ft) depth, and during the shorter incubation periods (two and four weeks). Mean zooplankton densities were greatest for Copepoda (88 %), then Daphnia spp. (10%) and other Cladocera (2.1%), while the zooplankton biomass assessment indicated Daphnia spp. had the greatest biomass (53.6%), then Copepoda (44.0%) and other Cladocera (2.5%). Mean overall zooplankton densities were the lowest observed since 1991. The cause was unclear, but may have been an artifact of human error. It seems unlikely that hydro-operations played a significant part in the reduction of zooplankton in light of the relatively friendly water year of 1998.

  9. Migrations in Slovenian geography textbooks

    Directory of Open Access Journals (Sweden)

    Jurij Senega?nik

    2013-12-01

    Full Text Available In Slovenia, the migrations are treated in almost all geographical textbooks for different levels of education. In the textbooks for the elementary school from the sixth to ninth grade, students acquire knowledge of the migrations by the inductive approach. Difficulty level of treatment and quantity of information are increasing by the age level. In the grammar school program a trail of gaining knowledge on migration is deductive. Most attention is dedicated to migrations in general geography textbooks. The textbooks for vocational and technical school programs deal with migrations to a lesser extent and with different approaches.

  10. Dispersal and migration

    Directory of Open Access Journals (Sweden)

    Schwarz, C.

    2004-06-01

    Full Text Available Ringing of birds unveiled many aspects of avian migration and dispersal movements. However, there is even much more to be explored by the use of ringing and other marks. Dispersal is crucial in understanding the initial phase of migration in migrating birds as it is to understand patterns and processes of distribution and gene flow. So far, the analysis of migration was largely based on analysing spatial and temporal patters of recoveries of ringed birds. However, there are considerable biases and pitfalls in using recoveries due to spatial and temporal variation in reporting probabilities. Novel methods are required for future studies separating the confounding effects of spatial and temporal heterogeneity of recovery data and heterogeneity of the landscape as well. These novel approaches should aim a more intensive and novel use of the existing recovery data by taking advantage of, for instance, dynamic and multistate modeling, should elaborate schemes for future studies, and should also include other marks that allow a more rapid data collection, like telemetry, geolocation and global positioning systems, and chemical and molecular markers. The latter appear to be very useful in the delineating origin of birds and connectivity between breeding and non–breeding grounds. Many studies of migration are purely descriptive. However, King and Brooks (King & Brooks, 2004 examine if movement patterns of dolphins change after the introduction of a gillnet ban. Bayesian methods are an interesting approach to this problem as they provide a meaningful measure of the probability that such a change occurred rather than simple yes/no response that is often the result of classical statistical methods. However, the key difficulty of a general implementation of Bayesian methods is the complexity of the modelling —there is no general userfriendly package that is easily accessible to most scientists. Drake and Alisauskas (Drake & Alisauskas, 2004 examine the philopatric movement of geese using a classic multi–state design. Previous studies of philopaty often rely upon simple return rates —however, good mark–recapture studies do not need to assume equal detection probabilities in space and time. This is likely the most important contribution of multi–state modelling to the study of movement. As with many of these studies, the most pressing problem in the analysis is the explosion in the number of parameters and the need to choose parsimonious modelss to get good precision. Drake and Alisauska demonstrate that model choice still remains an art with a great deal of biological insight being very helpful in the task. There is still plenty of scope for novel methods to study migration. Traditionally, there has been a clear cut distinction between birds being labelled as “migrant” or “resident” on the basis of field observations and qualitative interpretations of patterns of ring–recoveries. However, there are intermediate species where only part of the population migrates (partial migrants or where different components of the population migrate to different extents (differential migrants. Siriwardena, Wernham and Baillie (Siriwardena et al., 2004 develop a novel method that produces a quantitative index of migratory tendency. The method uses distributions of ringing–to–recovery distances to classify individual species’ patterns of movement relative to those of other species. The areas between species’ cumulative distance distributions are used with multi–dimensional scaling to produce a similarity map among species. This map can be used to investigate the factors that affect the migratory strategies that species adopt, such as body size, territoriality and distribution, and in studies of their consequences for demographic parameters such as annual survival and the timing of breeding. The key assumption of the method is the similar recovery effort of species over space and time. It would be interesting to overlay maps of effort to try and remove any induced artefacts in the data. Differences in

  11. Functorial Data Migration

    OpenAIRE

    Spivak, David I.

    2010-01-01

    In this paper we present a simple database definition language: that of categories and functors. A database schema is a small category and an instance is a set-valued functor on it. We show that morphisms of schemas induce three "data migration functors", which translate instances from one schema to the other in canonical ways. These functors parameterize projections, unions, and joins over all tables simultaneously and can be used in place of conjunctive and disjunctive que...

  12. Customer channel migration

    OpenAIRE

    Böhm, Martin

    2006-01-01

    Customer Channel Migration deals with the active management of a customer's channel usage behavior with the aim to increase her profitability and lifetime. Hence, the dissertation answers two distict questions: on one hand, it investigates the impact of channel use on a customer's profitability and lifetime. On the other hand, it is researched how a customer's channel usage behavior can be influenced and managed. The cumulative dissertation consists of five articles: the first article describ...

  13. Education, unemployment and migration

    OpenAIRE

    Eggert, Wolfgang; Krieger, Tim; Meier, Volker

    2009-01-01

    This paper studies a two-region model in which unemployment, education decisions and interregional migration are endogenous. The poorer region exhibits both lower wages and higher unemployment rates, and migrants to the richer region are disproportionally skilled. The brain drain from the poor to the rich region is accompanied by stronger incentives to acquire skills even for immobile workers. Regional shocks tend to affect both regions in a symmetric fashion, and skilled-biased technological...

  14. Migration of uranium

    International Nuclear Information System (INIS)

    Uranium migration is treated as a process leading to mobilization and concentration of uranium in ore deposits. During the formation of global zonation, uranium migration contributed to the enrichment of this radioactive metal in the Earth's crust. The process of upper mantle and crust fractionation and differentiation is the first cycle of the mobilization process which led to uranium enrichment in rocks in some areas of the upper Earth's crust that could be considered as the primordial uranium provinces. Uranium migration is related to the structural history of sial Earth's crust and sial magmatism. During orogeny conditions could be created for development of progressive metamorphism and for magma generation. The latter is the best process for uranium mobilization. The effectiveness of this process depends on the composition of the primordial rocks and the intensity of the process. The importance of the magmatism for uranium mobilization is due to the magmatic differentiation. Selectively mobilized felsitic parts of the rocks migrate and form felsitic magmatic portions, which mobilize uranium. Solutions are the best uranium mobilization agents. Their generation starts with water separation from local permeable reservoirs and finishes with water dissociation from minerals during their dehydration. Such solutions could be endogenous or exogenous, depending on the igneous or sedimentary rocks which have been deformed. Some of the solutions can have mixed origin, if deformed magmatic rocks contain exogenous water in pores and cracks and endogenous water in minerals. The mobilizing ability of the solutions depends on their energy, which could derive from their chemical compositions and from physical conditions of the geological environment. The movement of the mineralized solutions can be due to steam pressure and the pressure difference between the starting and the final point of the juvenile solutions, gravity for meteoric waters, convection in geoconvection cells, and water pressure in pressured hydrogeological systems. All these types of solution movement are considered, with emphasis on the more common ones. (author). 11 refs, 5 figs

  15. En fornemmelse for migration

    DEFF Research Database (Denmark)

    Schütze, Laura Maria

    2015-01-01

    Afhandlingen undersøger, hvordan sted, museets rolle som aktør og religion er relevante for produktionen af migration på Immigrantmuseet (2012) og i Københavns Museums udstilling At blive københavner (2010). Afhandlingen er baseret på udstillingsanalyse samt interview med relevant museumsfagligt personale. Siden slutningen af 1990erne har indvandring præget den kultur- og værdipolitiske debat i Danmark, der især har fremstillet indvandreren som 'den religiøse anden'. Indvandring har ligesom reli...

  16. Digitizing migration heritage

    DEFF Research Database (Denmark)

    Marselis, Randi

    2011-01-01

    Museums are increasingly digitizing their collections and making them available to the public on-line. Creating such digital resources may become means for social inclusion. For museums that acknowledge migration history and cultures of ethnic minority groups as important subjects in multiethnic societies, digitization brings new possibilities for reaching source communities. This article describes Web projects conducted at Museum Maluku in Utrecht, the Netherlands. The article focuses on the mu...

  17. International labour migration

    OpenAIRE

    Salt, John; Clarke, James; Wanner, Philippe ( Laboratoire de démographie et d'études familiales, Université de Genève, Switzerland )

    2004-01-01

    Le présent rapport décrit les grandes caractéristiques des migrations de la main-d’œuvre en Europe et les tendances observées ces dernières années. Il s’intéresse davantage aux travailleurs étrangers engagés dans un processus migratoire qu’aux populations immigrées déjà installées dans le pays d’accueil. Il examine les concepts et les définitions entourant la notion de travailleur migrant, présente brièvement les types et les sources de données, puis étudie les caractéristiques et les tendanc...

  18. Preliminary assessment of the zooplankton community composition in a region under the influence of a uranium mine (Caldas, Southeastern Brazil)

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Carla Rolim; Roque, Claudio Vitor; Ronqui, Leilane B.; Campos, Michelle B.; Rodgher, Suzelei; Nascimento, Marcos Roberto Lopes; Azevedo, Heliana de [Pocos de Caldas Laboratory, Brazilian Nuclear Energy Commission, MG (Brazil)], e-mail: carlarolimferrari@yahoo.com.br, e-mail: cvroque@cnen.gov.br, e-mail: pmarcos@cnen.gov.br, e-mail: leilanebio@yahoo.com.br, e-mail: michelle_borato@hotmail.com, e-mail: surodgher@uol.com.br, e-mail: hazevedo@cnen.gov.br; Wisniewski, Maria Jose dos Santos [Federal University of Alfenas (UNIFAL-MG), MG (Brazil). Lab. of Limnology], e-mail: czw@uol.com.br

    2009-07-01

    The Ore Treatment Unit consists of an open cast mine (CM), its mining waste areas, facilities for the physical treatment of the ore, and a chemical treatment plant for uranium extraction. At CM, the processes of acid drainage create effluents, which are treated by chemical processes and, thereafter, disposed of in Antas dam. The objective of the present study was to make an inventory of zooplanktonic and describe the physicochemical characteristics of site CM and at the site of treated effluents disposal (site 41), located at Antas dam. Water samples were collected in October/08 and January/09, in order to describe the abiotic variables and the zooplankton community. The average values of conductivity at sites CM and 41 were 2415 and 422 {mu}/cm{sup 2}, respectively. Values of pH at site CM remained acid, whereas, at site 41 we recorded values near neutrality. The concentrations of total nutrients at both sampling sites were higher in the rainy season. Zooplankton species richness present at site CM was lower than at site 41, and there were only two identified species Bosmina sp and Keratella americana. At site 41 we recorded more species, mainly of the Rotifera. Among Cladocera, we identified two species, regarding Copepoda, the orders Cyclopoida and Calanoida were present. At site CM the density values were lower compared to site 41. The preliminary assessment of the zooplankton community showed lower values of species richness and density at site CM, what may be probably explained by the adverse environmental conditions for zooplankton community. (author)

  19. Long-term changes of the crustacean zooplankton community in Lake Mjøsa, the largest lake in Norway

    Directory of Open Access Journals (Sweden)

    Jarl Eivind LØVIK

    2003-08-01

    Full Text Available Lake Mjøsa has been subject to an accelerating eutrophication from the 1950s to the mid 1970s, but comprehensive nutrient reduction efforts caused marked reductions of phytoplankton production and biomass during the 1980s, a process that continued during the 1990s. Zooplankton biomass and species composition was considerably affected during the eutrophication and subsequent oligotrophication. Total crustacean zooplankton biomass decreased along with decreasing algal biomass during the 1980s and 1990s. The seasonal means of zooplankton biomass were positively correlated with seasonal means of phytoplankton biovolume and chlorophyll-a, indicating a primarily bottom up regulation of the zooplankton biomass. Several herbivorous and omnivorous zooplankton species (Daphnia galeata, Bosmina longispina, Limnocalanus macrurus and Cyclops lacustris were probably negatively affected by reduced algal biomass, whereas other species (Holopedium gibberum and Thermocyclops oithonoides/Mesocyclops leuckarti seemed to be positively affected. H. gibberum disappeared in the 1960s, but reappeared in the 1980s after the significant reduction in algal biomass and primary production. The temporal trend of T. oithonoides/M. leuckarti indicated a strong competition with cladocerans (mainly B. longispina and D. galeata in periods with high algal biomass. Early warming of the lake could also have promoted a biomass increase of T. oithonoides/M. leuckarti in later years, although the mean epilimnion temperature did not correlate with seasonal mean biomass of these species. The seasonal mean biomass of Eudiaptomus gracilis, the dominant calanoid, showed substantial fluctuations with 6-7 years between tops, but a decreasing trend during the 1990s. However, there were no significant correlations between this species and any of the environmental variables. The study indicated that dominant cladocerans (D. galeata and B. longispina are decisive for the success of cisco (Coregonus albula, one of the most important planktivorous fish species, as also described by earlier studies. However it also demonstrated top down control on cladocerans in years with especially large stocks of cisco.

  20. Eutrophication-like response to climate warming: an analysis of Lago Maggiore (N. Italy zooplankton in contrasting years

    Directory of Open Access Journals (Sweden)

    Anna VISCONTI

    2008-08-01

    Full Text Available Global mean surface temperatures are increasing. All ecosystems are likely to be affected and there is much interest at present in predicting the effects. In freshwater environments, we expect to observe, among other things, effects similar to those observed under eutrophication, such as increases in zooplankton population density and biomass as a result of enhanced population growth rates. Lago Maggiore underwent rapid eutrophication during the 60s and 70s, with a return to oligotrophy during the 80s and the 90s. Thus, it provides a case study to test the hypothesized eutrophication-like effects of recent climate warming. More specifically, we compare zooplankton biomass and density during the exceptionally warm years of the recent oligotrophic phase with values during the non-warm years of oligotrophy, and during years of the mesotrophic phase. This permits an analysis of zooplankton biomass and density with respect to temperature increase compared with the effects of eutrophication. Zooplankton population density and biomass sharply increased in 2003, the warmest year of the last century, as a result of Cladocera, particularly Daphnia, attaining values typical of the mesotrophic phase. These values were exceptional compared to typical values and were strongly different from those attained during cooler years since re-oligotrophication. Mean annual values of zooplankton density and biomass recorded in 2003 were fully comparable to typical values during the mesotrophic period. This observation confirms the hypothesis of an overall eutrophication-like effect of climate warming. Seasonal trends, characterized by an earlier start of population growth, are consistent with the effects of an increase in water temperature, as observed in laboratory experiments on the reproductive and growth strategies of Daphnia.

  1. Zooplankton community of Parnaíba River, Northeastern Brazil / Comunidade zooplanctônica do Rio Parnaíba, Nordeste, Brasil

    Scientific Electronic Library Online (English)

    Ludmilla Cavalcanti Antunes, Lucena; Thaís Xavier de, Melo; Elvio Sergio Figueredo, Medeiros.

    2015-03-01

    Full Text Available Resumo Objetivo: O objetivo do presente estudo é apresentar uma lista de espécies de zooplâncton (Rotifera, Cladocera e Copepoda) do Rio Parnaíba, NE, Brasil, com comentários sobre a sua distribuição ao longo do rio e entre estações do ano. Métodos O zooplâncton foi amostrado usando uma rede de plâ [...] ncton (60 µm) e concentrado em um volume de 80 mL para ser levado ao laboratório. As amostragens ocorreram durante o período seco (Outubro 2010) e chuvoso (Abril 2011) e foram restritas a áreas marginais com profundidades entre 80 e 150 cm. Resultados Um total de 132 espécies foi registrado, sendo que durante a estação seca foram registradas 82 espécies e durante a estação chuvosa foram registradas 102 espécies. Rotifera representou 66,7% das espécies coletadas, seguido por Cladocera com 26,5% e Copepoda com 6,8%. Conclusões A riqueza de espécies coletada foi alta quando comparada com outros sistemas lóticos brasileiros. No contexto atual de transposição de águas e manejo de fluxo hidrológico nos rios do Nordeste, o presente estudo ressalta a importância do Rio Parnaíba e sua variação sazonal para a conservação da biodiversidade do semiárido brasileiro. Abstract in english Aim: The objective of the present work is to present a list of species of zooplankton (Rotifera, Cladocera and Copepoda) from the Parnaíba River. Additionally, we provide comments on their distribution along the river, and between dry and wet seasons. Methods Zooplankton was collected with a plankt [...] on net (60 µm mesh) and concentrated into a volume of 80 mL for further analysis, during the dry (October 2010) and wet (April 2011) seasons. Sampling was restricted to the marginal areas at depths between 80 and 150 cm. Results A total of 132 species was recorded among the three zooplankton groups studied. During the dry season a total of 82 species was registered and 102 species was registered for the wet season. Rotifera contributed with 66.7% of the species, followed by Cladocera (26.5%) and Copepoda (6.8%). Conclusions The richness of species observed was high compared to other large rivers in Brazil. In the context of current policies for water management and river diversions in northeastern Brazil, the present study highlights the importance of this river system for biodiversity conservation.

  2. Zooplankton assemblages from a tidal channel in the Bahía Blanca Estuary, Argentina

    Directory of Open Access Journals (Sweden)

    Mónica Susana Hoffmeyer

    2007-06-01

    Full Text Available In this study we investigate for the first time the zooplankton assemblages in a relatively small tidal channel called Bahía del Medio, situated in the middle-outer area of the Bahía Blanca Estuary, South of the Main channel. We focused the study on micro- and mesozooplankton assemblages with emphasis on tintinnids, copepods and meroplankton along the annual cycle 1997-1998. Fifteen species of tintinnids belonging to 6 genera were observed in the study area, the mean total tintinnid abundance fluctuating between 3.4 x 10(6 ind. m-3 and 5.1 x 10(6 ind m-3. The mesozooplankton comprised 11 taxa, total abundance fluctuating between 449 ind m-3 in March 1997 and only 1 ind m-3 in October 1997. The channel proved to be spatially homogeneous in its physical and biochemical features. Micro- and mesozooplankton abundance displayed a high degree of spatial homogeneity, though the seasonal variation in both environment and zooplankton was significant. Comparison with the zooplankton observed at a station in the Main channel of the estuary showed differences in number of taxa represented, a general lower abundance of both assemblages and the presence of some rare species, a fact which is discussed.Neste estudo pesquisamos pela primeira vez as associações do zooplâncton num pequeno canal de maré, relativamente novo e chamado Bahía del Medio, localizado na região média-exterior do estuário da Bahía Blanca e ao sul do canal principal. Focalizamos o estudo no micro- e mesozooplâncton com ênfase nos grupos Tintinnida, Copepoda e meroplâncton, ao longo do ciclo anual 1997-1998. Foram observadas 15 espécies de Tintinnida pertencentes a 6 gêneros; a abundância média total de Tintinnida variou entre 3,4 x 10(6 ind. m-3 e 5,1 x 10(6 ind. m-3. O mesozooplâncton apresentou 11 taxa e uma abundância total entre 449 ind. m-3 em março de1997 e 1 ind. m-3 em outubro de 1997. O canal provou ser espacialmente homogêneo em suas características biológicas, químicas e físicas. A abundância do micro- e mesozooplâncton mostrou um alto grau de homogeneidade espacial, embora a variaçao estacional fosse significativa nas características do meio ambiente e do zooplâncton. A comparação com o zooplâncton observado em uma estação de amostragem no canal principal do estuário mostrou diferenças no número de taxa, na abundância, em geral mais baixa, e na presença de algumas espécies raras , fato esse comentado.

  3. Dominance shift of zooplankton species composition in the central Strait of Georgia, British Columbia during 1997 Cambio en el zooplancton dominante del estrecho de Georgia, British Columbia durante 1997

    Directory of Open Access Journals (Sweden)

    Martha J. Haro-Garay

    2008-08-01

    Full Text Available A multivariate analysis of the zooplankton was completed during the 1997 annual cycle in the central Strait of Georgia, Canada. Sampling was conducted monthly in a single location (49° 15' 0" N, 123° 44' 9" W. The study used the species as environment descriptors, and examined possible patterns of species associations. Principal components analysis showed two groups of species coinciding with changes in vertical salinity structure arising from two phases of the Fraser River runoff. Group I was dominant during fall-winter to early spring related to low-runoff season. Group II was dominant during late spring to summer, and related to high-runoff season. Notable results were the scarcity of Neocalanus plumchrus and Euphausia pacifica, typically dominant species of zooplankton, coincident with river runoff levels lower than previous years and with an early phytoplankton bloom. We speculate that these results are a consequence of El Niño 1997 event, combined with the climate change expressed as a decreased freshwater runoff. Low abundance of Neocalanus plumchrus and Euphausia pacifica affected the zooplankton biomass. Consequently, substitute dominant P. pacifica and Cyphocaris challengeriprobable play an important role in trophic dynamics while N. plumchrus and E. pacifica are scarce. Both amphipods feed on small zooplankters that feed on nanoplankton, concentrating food energy and biomass from small zooplankters. This suggests that P. pacifica and C. challengeri are an important link in the trophic ecology of the Strait of Georgia. In conclusion, shifts in zooplankton species dominance highly likely have an effect on juvenile zooplanktivorous salmon specie.Se realizó un análisis multivariado del zooplancton de la parte central del estrecho de Georgia, Canadá durante 1997, con muestreos mensuales en una localidad (49° 15' 0" N, 123° 44' 9" W. Las especies se usaron como descriptores del ambiente para examinar posibles patrones de asociación. Mediante análisis de componentes principales se encontraron dos grupos coincidentes con cambios en la estructura vertical de la salinidad inducidos por las fases de flujo intensa y débil del Río Fraser. El grupo I estuvo presente de septiembre a marzo durante la fase de flujo débil del río. El grupo II durante la fase de flujo intensa de mayo a julio. Fue notoria la escasez de Neocalanus plumchrus y Euphausia pacifica, especies dominantes típicas, coincidente con niveles de flujo del Río Fraser inferiores a años previos, y con un florecimiento de fitoplancton temprano. Se especula que estos resultados son consecuencia de El Niño 1997, combinado con cambio climático expresado en la baja descarga del río. La baja abundancia de Neocalanus plumchrus y Euphausia pacifica afectó la biomasa zooplanctónica, en su lugar dominaron Parathemisto pacifica y Cyphocaris challengerique depredan al zooplancton pequeño que se alimenta de nanoplancton, concentrando la energía y biomasa del zooplancton pequeño. Esto sugiere que Parathemisto pacifica y Cyphocaris challengeri son un elemento de enlace importante en la ecología trófica del Estrecho de Georgia cuando N. plumchrus y E. pacifica son escasas. Se concluye que los cambios en la dominancia de especies muy probablemente tienen efecto sobre el salmón juvenil y los peces zooplanctófagos.

  4. Vertical 2D Heterostructures

    Science.gov (United States)

    Lotsch, Bettina V.

    2015-07-01

    Graphene's legacy has become an integral part of today's condensed matter science and has equipped a whole generation of scientists with an armory of concepts and techniques that open up new perspectives for the postgraphene area. In particular, the judicious combination of 2D building blocks into vertical heterostructures has recently been identified as a promising route to rationally engineer complex multilayer systems and artificial solids with intriguing properties. The present review highlights recent developments in the rapidly emerging field of 2D nanoarchitectonics from a materials chemistry perspective, with a focus on the types of heterostructures available, their assembly strategies, and their emerging properties. This overview is intended to bridge the gap between two major—yet largely disjunct—developments in 2D heterostructures, which are firmly rooted in solid-state chemistry or physics. Although the underlying types of heterostructures differ with respect to their dimensions, layer alignment, and interfacial quality, there is common ground, and future synergies between the various assembly strategies are to be expected.

  5. Moisture influence on sorption and migration of Cs-137 and Sr-90 in peat soils in the presence of electrolytes in pore solution

    International Nuclear Information System (INIS)

    The results of laboratory and field experiments on regularities of the vertical migration of Cs-137 and Sr-90 in peat soils at different moisture regimes and in the presence of electrolytes in pore solution are represented

  6. Vertical transmission of Kaposi's sarcoma.

    OpenAIRE

    McCarthy, G A; Kampmann, B; Novelli, V.; Miller, R. F.; Mercey, D. E.; Gibb, D.

    1996-01-01

    AIDS related Kaposi's sarcoma is commonly seen in homosexual men, only occasionally in men and women with heterosexually acquired HIV, and extremely rarely in children. The case of an HIV infected mother and her vertically infected child who both developed visceral Kaposi's sarcoma is reported. It is proposed that the putative Kaposi's sarcoma agent may also be transmitted vertically.

  7. Species composition, abundance and distribution of zooplankton in a tropical eutrophic lake: Lake Catemaco, México

    Directory of Open Access Journals (Sweden)

    Roberto E. Torres-Orozco B.

    1998-06-01

    Full Text Available From April 1992 to May 1993, zooplankton samples were collected monthly by means of horizontal tows in nine sites of the lake. Prior to the towing, temperature of surface water, transparency (Secchi, pH and dissolved oxygen were evaluated. A total of 31 zooplankton forms, including 14 species of rotifers, three copepods, five cladocerans and one ostracod, as well as protozoans (mainly vorticellids and ciliates, were detected. Rotifers were the dominant organisms, mainly Brachionus havanaensis (27.6 ind l-¹, B. angularis (6.9 ind l-¹, Keratella cochlearis (4.9 ind l-¹, Conochilus unicornis (10.8 ind l-¹ and C. dossuarius (3.1 ind l-¹. Within crustaceans, higher densities were shown by larvae (nauplii and copepodites of calanoid (16.8 ind l-¹ and cyclopoid (15.6 ind l-¹ copepods, as well as Arctodiaptomus dorsalis (2 ind l-¹, Mesocyclops edax (0.5 ind l-¹, and the cladocerans Bosmina longirostris (1.6 ind l-¹ and Diaphanosoma brachyurum (0.5 ind l-¹. Densities were low, probably because of a high predation pressure imposed by fishes. A gradual increase in total zooplankton density related with a progressive diminution of transparency was observed throughout the sampling period. Zooplankton densities in the stations located at the central part of the lake were higher when compared with those at a more peripheral position. Time variation in rotifer's relative abundance was directly related to temperature fluctuations. The low density and diversity values, the small size of the zooplankters, the presence of an important number of indicator species, and the calanoid copepods: other planktonic crustaceans low ratio, are all indicators of eutrophy. Evidences suggest that the eutrophication process of Lake Catemaco is still progressing rapidly.Entre abril de 1992 y mayo de 1993, se realizaron mensualmente recolectas subsuperficiales de zooplancton, con red, en nueve localidades del lago, en donde también se determinaron la temperatura superficial, la visibilidad del disco de Secchi, el pH y la concentración de oxígeno disuelto. Entre las 31 formas de plancton detectadas en las distintas submuestras se registraron 14 especies de rotíferos, tres de copépodos, cinco de cladóceros y un ostrácodo, además de protozoarios, principalmente vorticélidos y ciliados. Los rotíferos fueron los organismos más abundantes; Brachionus havanaensis fue la especie dominante, seguida por Conochilus unicornis, Brachionus angularis, Keratella cochlearis y Conochilus dossuarius. Entre los copépodos destacaron Arctodiaptomus dorsalis y Mesocyclops edax, además de sus nauplios y copepoditos, y entre los cladóceros Diaphanosoma brachyurum, Bosmina longirostris, y Bosminopsis sp. Las densidades observadas en los grupos dominantes del zooplancton fueron bajas; sin embargo, a lo largo del período de estudio se observó un incremento paulatino en la densidad zooplantónica total, relacionado con una disminución progresiva de la visibilidad del disco de Secchi. Las densidades más altas se detectaron en los sitios más alejados de la costa. Las variaciones estacionales en la abundancia relativa de los rotíferos estuvieron estrechamente relacionadas con las fluctuaciones de la temperatura. Los bajos valores de densidad y diversidad, el pequeño tamaño de los zooplancters, la presencia de un importante número de especies indicadoras y la baja razón copepodos calanoides: otros crustáceos planctónicos, son todos indicadores de condiciones eutróficas. Además, existen evidencias de que el proceso de eutrofización del lago está avanzando aceleradamente.

  8. The distribution of micro zooplankton in the lagoon environments; La distribuzione del microzooplancton negli ambienti lagunari

    Energy Technology Data Exchange (ETDEWEB)

    Grenni, P.; Creo, C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1998-07-01

    The aim of this work is to verify the possible use of micro zooplankton as a biological indicator in aquatic environments. In particular, studies carried out in lagoon environments are reported, relatively to the Venice lagoon and the Pontine coastal lakes (Italy). New methodologies to assess the micro plankton component are developed and tested, particularly the concentration and count steps. The use of the same methodologies to assess nano plankton component, as biological indicator. are reported. [Italian] Nel presente lavoro viene analizzata la possibilita' di utilizzare il microzooplancton quale indicatore biologico negli ambienti acquatici (mmarini, acquadulcicoli, salmastri). In particolare, vengono riportati gli studi effettuati dall'ENEA (National Agency for New Technology, Energy and the Environment) su tale componente in ambienti lagunari, con riferimento alla laguna di Venezia e alle lagune pontine.

  9. Trade Liberalisation and Vertical Integration

    DEFF Research Database (Denmark)

    Bache, Peter Arendorf; Laugesen, Anders

    2013-01-01

    We build a three-country model of international trade in final and intermediate goods and study the relation between different types of trade liberalisation and vertical integration. Firms are heterogeneous with respect to both productivity and factor intensity as observed in data. Final-good producers face decisions on exporting, vertical integration of intermediate-input production, and whether the intermediate-input production should be offshored to a low-wage country. We find that due to firm-level complementarities, the shares of final-good producers that pursue either vertical integration, offshoring, or exporting are all increasing when intermediate- or final-goods trade is liberalised and when the cost of vertical integration is reduced. At the same time, one will observe individual firms that shift away from either vertical integration, offshoring, or exporting. All these results hold for a class of productivity distributions to which the Pareto distribution belongs.

  10. Elastic Modeling and Migration in Earth Models

    Science.gov (United States)

    Cunha, Carlos Alves, Filho

    Migration and inversion of marine seismic data using the elastic wave equation requires the transformation of the recorded pressure data into a vector particle-displacement field. This can be done easily when the recording geometry samples the wavefield both horizontally and vertically. However, only experimental surveys have cables located at different depths. Using a few assumptions, I derive a method for performing this transformation, which is applicable to standard surveys. The assumptions are: smooth water surface, cable nearly parallel to water surface, and perfect seismic -reflection at the water surface. Results in a realistic example, where these assumptions are only partially fulfilled, demonstrate that the method is robust. Elastic, reverse-time migration/inversion schemes in the space-time domain are usually implemented by finite -difference or finite-element methods. When imaging beyond structures, a dynamically accurate scheme must be used. For models characterized by layers with sharp boundaries traditional finite-difference methods fail to correctly describe the dynamics of the propagation process. Failure comes from the lack of distinction between model and field variables; the same difference operator is applied to discontinuous (model) and continuous (wavefield) components. The problem is solved with a modified finite-difference scheme (dual -operator), which uses long operators for wavefields, short operators for elastic parameters, Shoenberg-Muir (1989) equivalence relations and a modified Virieux (1984) staggered grid scheme. Tests show that the the dual-operator is dynamically more accurate than traditional finite-difference schemes and comparable to Haskell-Thomson schemes. In structurally complex media, accurate recovery of angle-dependent reflectivities requires elastic prestack migration. Mode separation can be done before or after depth extrapolation. Though more complex, the latter is more complete because it images mode-converted waves. Standard depth-extrapolation and imaging approaches are unsuitable for true-reflectivity recovery. I introduce an extrapolation method which properly compensates for transmission/conversion losses. This method is combined with an imaging condition that performs the plane-wave decomposition of the downward extrapolated data to define the plane-wave-response (PWD) migration. The four image-cubes generated by the PWD migration correspond to the plane-wave angle-dependent reflectivities for PP, PS, SP, and SS modes, and directly relate to the Zoeppritz equations because they represent the in-depth plane-wave response of the medium.

  11. Zooplankton data collected using net casts from the FRANCISCO DE ULLOA in the North Pacific Ocean from 01 January 1999 to 31 January 1999 (NODC Accession 0000912)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using net casts in the North Pacific Ocean from FRANCISCO DE ULLOA. Data were collected from 01 January 1999 to 31 January 1999....

  12. Zooplankton and other data collected in Northwest Atlantic Ocean from CTD, bottle casts, and other instruments from 10 September 1963 to 24 August 1964 (NODC Accession 7101509)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton and other data were collected using CTD, bottle casts, and other instruments in the Northwest Atlantic Ocean. Data were collected from 10 September 1963...

  13. Size-fractioned zooplankton biomass data sampled during the Institute of Marine Research Norwegian Sea survey from 1995 to 2005 (NODC Accession 0049894)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data were downloaded from the COPEPOD data base website. The dataset contains zooplankton data from the Institute of Marine Research (Bergen Norway) Norwegian...

  14. The distribution of the standing crop of zooplankton in the Southern Ocean, 02 January 1932 to 18 October 1951 (NODC Accession 0000842)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using net casts in the Southern Ocean from the DISCOVERY II. Data were collected from 02 January 1932 to 18 October 1951. Data were...

  15. Zooplankton data collected using net casts from the ALMIRANTE SALDANHA in the Northeast Atlantic Ocean from 05 November 1958 to 15 January 1959 (NODC Accession 0000942)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using net casts in the Northeast Atlantic Ocean from ALMIRANTE SALDANHA. Data were collected from 05 November 1958 to 15 January...

  16. Zooplankton species identities and other data collected by ATLANTIS II from net casts in NW Atlantic Ocean from 23 November 1988 to 04 December 1988 (NODC Accession 9500081)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities and other data were collected using net casts in the Northwest Atlantic Ocean from ATLANTIS II. Data were collected from 23 November...

  17. Zooplankton biomass data collected by Research Institute of Marine Fisheries & Oceanography (PINRO) from 1958-03-25 to 1964-06-18 (NODC Accession 0070127)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton biomass data collected in North Atlantic Ocean, Greenland Sea, North Sea, Norwegian Sea, and Bering Sea from 03 Mar 1958 to 18 Jun 1964 by PINRO. Data...

  18. NODC Standard Product: International ocean atlas Volume 7 - 36 year time series (1963-1998) of zooplankton, temperature and salinity in the White Sea (NODC Accession 0099242)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The present study is based on marine physical and biological observations since 1961. The data on zooplankton has been collected since 1963 in the vicinity of the...

  19. GLOBEC Zooplankton Data Sets collected by net on multiple cruises from 10/13/1997 - 5/6/1999 (NODC Accession 0000069)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using net casts from ALPHA HELIX in the Gulf of Alaska. Data were collected from 10 October 1997 to 09 may 1999. Data were collected...

  20. Migration and loving

    OpenAIRE

    Gevrek, Deniz

    2010-01-01

    This paper explores the relationship between anti-miscegenation laws, interracial marriage and black males' geographical distribution in the U.S. during and after the Great Migration. The U.S. Supreme Court decision in the case of Loving v. Virginia in 1967, which forced the last 16 Southern states to strike down their anti-miscegenation laws, creates a unique opportunity to explore the impact of an exogenous change in a state's laws regulating interracial marriages. Analyzing the U.S. Census...