WorldWideScience

Sample records for zooplanktonic model organism

  1. Organic carbon content of tropical zooplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.

    In the Zuari and Mandovi estuaries variations in organic carbon of zooplankton are 26.4-38.8 and 24-39.9% of dry weight respectively. Maximum carbon content of estuarine zooplankton is observed in November. Organic carbon in nearshore and oceanic...

  2. Effect of Organic Fertilizers on Zooplankton Production | Orji ...

    African Journals Online (AJOL)

    Effect of Organic Fertilizers on Zooplankton Production. ... Journal of Agriculture and Food Sciences ... The aquaria were thoroughly washed, filled with 20litres of bore-hole water, fertilized with the respective organic manures after 4 days fermentation and inoculated with zooplankton samples collected from an earthen fish ...

  3. A new modelling approach for zooplankton behaviour

    Science.gov (United States)

    Keiyu, A. Y.; Yamazaki, H.; Strickler, J. R.

    We have developed a new simulation technique to model zooplankton behaviour. The approach utilizes neither the conventional artificial intelligence nor neural network methods. We have designed an adaptive behaviour network, which is similar to BEER [(1990) Intelligence as an adaptive behaviour: an experiment in computational neuroethology, Academic Press], based on observational studies of zooplankton behaviour. The proposed method is compared with non- "intelligent" models—random walk and correlated walk models—as well as observed behaviour in a laboratory tank. Although the network is simple, the model exhibits rich behavioural patterns similar to live copepods.

  4. SEAPODYM-LTL: a parsimonious zooplankton dynamic biomass model

    Science.gov (United States)

    Conchon, Anna; Lehodey, Patrick; Gehlen, Marion; Titaud, Olivier; Senina, Inna; Séférian, Roland

    2017-04-01

    Mesozooplankton organisms are of critical importance for the understanding of early life history of most fish stocks, as well as the nutrient cycles in the ocean. Ongoing climate change and the need for improved approaches to the management of living marine resources has driven recent advances in zooplankton modelling. The classical modeling approach tends to describe the whole biogeochemical and plankton cycle with increasing complexity. We propose here a different and parsimonious zooplankton dynamic biomass model (SEAPODYM-LTL) that is cost efficient and can be advantageously coupled with primary production estimated either from satellite derived ocean color data or biogeochemical models. In addition, the adjoint code of the model is developed allowing a robust optimization approach for estimating the few parameters of the model. In this study, we run the first optimization experiments using a global database of climatological zooplankton biomass data and we make a comparative analysis to assess the importance of resolution and primary production inputs on model fit to observations. We also compare SEAPODYM-LTL outputs to those produced by a more complex biogeochemical model (PISCES) but sharing the same physical forcings.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    The WHAM-F TOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (F TOX ), 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

  6. Predictive models for monitoring and analysis of the total zooplankton

    Directory of Open Access Journals (Sweden)

    Obradović Milica

    2014-01-01

    Full Text Available In recent years, modeling and prediction of total zooplankton abundance have been performed by various tools and techniques, among which data mining tools have been less frequent. The purpose of this paper is to automatically determine the dependency degree and the influence of physical, chemical and biological parameters on the total zooplankton abundance, through design of the specific data mining models. For this purpose, the analysis of key influencers was used. The analysis is based on the data obtained from the SeLaR information system - specifically, the data from the two reservoirs (Gruža and Grošnica with different morphometric characteristics and trophic state. The data is transformed into optimal structure for data analysis, upon which, data mining model based on the Naïve Bayes algorithm is constructed. The results of the analysis imply that in both reservoirs, parameters of groups and species of zooplankton have the greatest influence on the total zooplankton abundance. If these inputs (group and zooplankton species are left out, differences in the impact of physical, chemical and other biological parameters in dependences of reservoirs can be noted. In the Grošnica reservoir, analysis showed that the temporal dimension (months, nitrates, water temperature, chemical oxygen demand, chlorophyll and chlorides, had the key influence with strong relative impact. In the Gruža reservoir, key influence parameters for total zooplankton are: spatial dimension (location, water temperature and physiological groups of bacteria. The results show that the presented data mining model is usable on any kind of aquatic ecosystem and can also serve for the detection of inputs which could be the basis for the future analysis and modeling.

  7. A stochastic analysis for a phytoplankton-zooplankton model

    International Nuclear Information System (INIS)

    Ge, G; Wang, H-L; Xu, J

    2008-01-01

    A simple phytoplankton-zooplankton nonlinear dynamical model was proposed to study the coexistence of all the species and a Hopf bifurcation was observed. In order to study the effect of environmental robustness on this system, we have stochastically perturbed the system with respect to white noise around its positive interior equilibrium. We have observed that the system remains stochastically stable around the positive equilibrium for same parametric values in the deterministic situation

  8. FORMATION OF BACTERIAL AND ZOOPLANKTON COMPONENT OF NATURAL FOOD BASE UNDER EFFECT OF TRADITIONAL ORGANIC FERTILIZERS

    Directory of Open Access Journals (Sweden)

    S. Krazhan

    2013-12-01

    Full Text Available Purpose. Characterization of bacteria and zooplankton in rearing ponds using traditional fertilizers: cattle manure and bird droppings in modern conditions for fish farming. Methodology. Material collection and processing were carried out according to conventional hydrochemical and hydrobiological methods. Findings. We consider forming of bacteria and zooplankton component of natural food base of Irkliiv herbivorous fish nursery rearing ponds under the influenced of traditional organic fertilizers such as bird droppings (0,12 t/ha and cattle manure (2,0 t/ha. Each pond was planted by ongrowing Nyvka carp larvae (40,0 thousand ind./ha with silver carp (1,0 thousand ind./ha and grass carp larvae (1,0 thousand ind./ha. Qualitative and quantitative development of bacteria and zooplankton in fish-breeding ponds was investigated. The results show that in the development of the studied invertebrate groups of zooplankton in production ponds had no significant differences, except for rotifers, which group prevailed by the biomass to 3,6 times in the pond with the introduction of humus. Originality. The parameters of bacteria and zooplankton by the application of traditional organic fertilizers at present fish farming are studied. Practical value. These quantitative indicators of bacteria and zooplankton of fish-rearing ponds with water supply from Kremenchug reservoir, the application of cattle manure and bird droppings could be offered as an optimum data at present fish production stage.

  9. Structural-functional organization of the littoral zooplankton communities of the Kremenchutskiy reservoir

    Directory of Open Access Journals (Sweden)

    Z. Burian

    2018-03-01

    Full Text Available Purpose. To find out the present state of the structural and functional organization of the littoral zooplankton communities of the upper Kremenchuk reservoir in the area of ​​the Kaniv Nature Reserve. Methodology. The material was collected in the summer time of 2016 at six stations of the littoral zone of the upper Kremenchug reservoir. The collection and analysis were carried out using generally accepted methods. The objects of the research were representatives of three main groups of zooplankton (rotifers, cladocerans, copepods, as well as ostracods and larvae of bivalve molluscs. Statistical data processing was done in MS Excel 2013. Findings. The results of the study represent the present state and organisation of littoral zooplankton. The species richness of the littoral zooplankton of the upper Kremenchug reservoir was presented by 48 species. There are 20 species of monogonont rotifers, 18 cladocerans species and copepods – 10. The representatives of the rotifer-cladoceran complex dominated in the taxonomic composition that can be explained by the preservation of the river regime and the rheophilic conditions in this part of the reservoir. The analysis showed that according to the ecological spectrum of zooplankton groups, the representatives of the pelagic group dominated – 47.92%. As for the feeding type, the largest share was represented by the non-predatory group – 64.58%. After analyzing of the quantitative indices (density and biomass of zooplankton, it was found that they were lower than average for overgrown biotopes (112580 ± 129914 ind./m³ і 1.83 ± 2.07 g/m³ and low for open water (26160 ± 19161 ind./m³ і 0,82 ± 0,86 g/m³. Originality. The present state of structural and functional organization of the littoral zooplankton communities of the upper Kremenchug reservoir has been revealed. Practical significance. The conducted studies give the information about the structural and functional organization of the

  10. Organic carbon content of zooplankton from the nearshore waters of Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Gajbhiye, S.N.; Sayed, F.Y.

    Organic carbon content of zooplankton in the Versova Creek and Thana Creek (polluted areas), off Versova and off Mahim, Bombay, India (relatively unpolluted areas) varied respectively from 21.4-30, 13.2-38.4, 21.6-30 and 25.8-39.6% dry weight...

  11. Biomass, organic carbon and calorific content of zooplankton from the Arabian Sea off Central West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Nair, V.R.

    Organic carbon content and calorific values of zooplankton varied from 18.35 to 32.49% (av. 27.8%) and from 2.56 to 4.71 k cal. g-1 dry wt (av. 3.99) respectively. Areawise off Gujarat sustained higher standing stock of zooplankton (77.18 mg m-3...

  12. Extended probit mortality model for zooplankton against transient change of PCO(2).

    Science.gov (United States)

    Sato, Toru; Watanabe, Yuji; Toyota, Koji; Ishizaka, Joji

    2005-09-01

    The direct injection of CO(2) in the deep ocean is a promising way to mitigate global warming. One of the uncertainties in this method, however, is its impact on marine organisms in the near field. Since the concentration of CO(2), which organisms experience in the ocean, changes with time, it is required to develop a biological impact model for the organisms against the unsteady change of CO(2) concentration. In general, the LC(50) concept is widely applied for testing a toxic agent for the acute mortality. Here, we regard the probit-transformed mortality as a linear function not only of the concentration of CO(2) but also of exposure time. A simple mathematical transform of the function gives a damage-accumulation mortality model for zooplankton. In this article, this model was validated by the mortality test of Metamphiascopsis hirsutus against the transient change of CO(2) concentration.

  13. Modelling the relationship between zooplankton biomass and environmental variations in the distribution of 210Po during a one year cycle in northwestern Mediterranean coastal waters.

    Science.gov (United States)

    Färber Lorda, Jaime; Tateda, Yutaka; Fowler, Scott W

    2017-08-01

    To clarify the relationship between zooplankton biomass and the environmental kinetics of the natural radionuclide 210 Po during a one-year period (October 1995 to November 1996) in northwestern Mediterranean coastal waters, a modelling analysis was applied. Using 210 Po concentrations in seawater and zooplankton, the 210 Po uptake rate constant from food for zooplankton was evaluated using a biokinetics calculation involving the uptake and the excretion rate constants between seawater and zooplankton. Using the transfer constants obtained, the 210 Po concentrations in zooplankton were reconstructed and validated by observed concentrations. The simulation results were in good agreement with the measured 210 Po concentrations in zooplankton. Assuming that 210 Po fecal excretion represents the majority of the excretion of 210 Po from zooplankton, the fecal matter associated 210 Po vertical flux was calculated, and compared with the observed vertical fluxes of 210 Po measured in sediment traps. The modelling evaluation showed that fecal pellet vertical transport could not fully explain the observed sinking fluxes of particulate organic matter at 150 m depth, suggesting that other sinking biodetrital aggregates are also important components of the plankton-derived vertical flux of 210 Po. The relationship between 210 Po concentration in seawater and that in rain and dry fallout and their potential effect on 210 Po concentrations in zooplankton at this location were also examined. A similar, but diphased trend between 210 Po in zooplankton and 210 Po in rain and dry fallout deposition rate was demonstrated. 210 Po concentrations in the dissolved phase of seawater tended to diminish as mean daily rainfall increased suggesting that rain inputs serve as a 210 Po dilution mechanism in seawater at this location. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Estimation of the toxicity of pollutants to marine phytoplanktonic and zooplanktonic organisms

    International Nuclear Information System (INIS)

    1989-01-01

    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

  15. Grazing experiments and model simulations of the role of zooplankton in Phaeocystis food webs

    Science.gov (United States)

    Verity, P. G.

    2000-08-01

    A combined empirical and modelling study was conducted to further examine the potential importance of grazing by zooplankton in pelagic food webs in which Phaeocystis is a significant or dominant component. Laboratory experiments were designed to measure ingestion of Phaeocystis and other potential prey items which co-occur with Phaeocystis. Grazers included copepods and ciliates, and prey included Phaeocystis colonies and solitary cells, diatoms, ciliates, bacteria, and detritus. These data were expressed in the model currency of nitrogen units, and fit to hyperbolic tangent equations which included minimum prey thresholds. These equations and literature data were used to constrain a food web model whose purpose was to investigate trophic interactions rather than to mimic actual events. Nevertheless, the model output was similar to the general pattern and magnitude of development of Phaeocystis-diatom communities in some environments where they occur, e.g. north Norwegian waters. The model included three forms of nitrogen, three phytoplankton groups, bacteria, two zooplankton groups, and detritus, with detailed flows between compartments. An important component of the model was inclusion of variable prey preferences for zooplankton. The experiments and model simulations suggest several salient conclusions. Phaeocystis globosa colonies were eaten by a medium-sized copepod species, but ingestion appeared to be strongly dependent upon a proper size match between grazer and prey. If not, colonies were eaten little if at all. Phaeocystis solitary cells were ingested rapidly by ciliate microzooplankton, in agreement with prior literature observations. In contrast, detritus was eaten comparatively slowly by both ciliates and copepods. Both types of zooplankton exhibited apparent minimum prey thresholds below which grazing did not occur or was inconsequential. Model simulations implied that transitions between life cycle stages of Phaeocystis may potentially be important

  16. Bioenergetics modeling of the annual consumption of zooplankton by pelagic fish feeding in the Northeast Atlantic

    DEFF Research Database (Denmark)

    Bachiller, Eneko; Utne, Kjell Rong; Jansen, Teunis

    2018-01-01

    The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by some of the most commercially important planktivorous fish stocks in the Northeast Atlantic, namely Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting (Micromesi......The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by some of the most commercially important planktivorous fish stocks in the Northeast Atlantic, namely Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting...

  17. Crustacean zooplankton release copious amounts of dissolved organic matter as taurine in the ocean.

    Science.gov (United States)

    Clifford, Elisabeth L; Hansell, Dennis A; Varela, Marta M; Nieto-Cid, Mar; Herndl, Gerhard J; Sintes, Eva

    2017-11-01

    Taurine (Tau), an amino acid-like compound, is present in almost all marine metazoans including crustacean zooplankton. It plays an important physiological role in these organisms and is released into the ambient water throughout their life cycle. However, limited information is available on the release rates by marine organisms, the concentrations and turnover of Tau in the ocean. We determined dissolved free Tau concentrations throughout the water column and its release by abundant crustacean mesozooplankton at two open ocean sites (Gulf of Alaska and North Atlantic). At both locations, the concentrations of dissolved free Tau were in the low nM range (up to 15.7 nM) in epipelagic waters, declining sharply in the mesopelagic to about 0.2 nM and remaining fairly stable throughout the bathypelagic waters. Pacific amphipod-copepod assemblages exhibited lower dissolved free Tau release rates per unit biomass (0.8 ± 0.4 μmol g -1 C-biomass h -1 ) than Atlantic copepods (ranging between 1.3 ± 0.4 μmol g -1 C-biomass h -1 and 9.5 ± 2.1 μmol g -1 C-biomass h -1 ), in agreement with the well-documented inverse relationship between biomass-normalized excretion rates and body size. Our results indicate that crustacean zooplankton might contribute significantly to the dissolved organic matter flux in marine ecosystems via dissolved free Tau release. Based on the release rates and assuming steady state dissolved free Tau concentrations, turnover times of dissolved free Tau range from 0.05 d to 2.3 d in the upper water column and are therefore similar to those of dissolved free amino acids. This rapid turnover indicates that dissolved free Tau is efficiently consumed in oceanic waters, most likely by heterotrophic bacteria.

  18. Zooplankton Hydrodynamics

    DEFF Research Database (Denmark)

    Wadhwa, Navish

    flow disturbances that may attract predators. The first part of this thesis attempts to quantify the trade-offs associated with the swimming behaviour of diverse zooplankton. We measured the swimming kinematics and flow fields around the 'jumping' copepod Acartia tonsa at various stages of its life....... We studied how sensing modes and their respective ranges depend on body size. We investigated the physiological constraints on sense organs, together with the physics of signal generation, transmission, and reception. Our analysis revealed a hierarchy of sensing modes - with increasing size, a larger...

  19. Modeled sensitivity of Lake Michigan productivity and zooplankton to changing nutrient concentrations and quagga mussels

    Science.gov (United States)

    Pilcher, Darren J.; McKinley, Galen A.; Kralj, James; Bootsma, Harvey A.; Reavie, Euan D.

    2017-08-01

    The recent decline in Lake Michigan productivity is often attributed to filter feeding by invasive quagga mussels, but some studies also implicate reductions in lakewide nutrient concentrations. We use a 3-D coupled hydrodynamic-biogeochemical model to evaluate the effect of changing nutrient concentrations and quagga mussel filtering on phytoplankton production and phytoplankton and zooplankton biomass. Sensitivity experiments are used to assess the net effect of each change separately and in unison. Quagga mussels are found to have the greatest impact during periods of isothermal mixing, while nutrients have the greatest impact during thermal stratification. Quagga mussels also act to enhance spatial heterogeneity, particularly between nearshore-offshore regions. This effect produces a reversal in the gradient of nearshore-offshore productivity: from relatively greater nearshore productivity in the prequagga lake to relatively lesser nearshore productivity after quaggas. The combined impact of both processes drives substantial reductions in phytoplankton and zooplankton biomass, as well as significant modifications to the seasonality of surface water pCO2, particularly in nearshore regions where mussel grazing continues year-round. These results support growing concern that considerable losses of phytoplankton and zooplankton will yield concurrent losses at higher trophic levels. Comparisons to observed productivity suggest that both quagga mussel filtration and lower lakewide total phosphorus are necessary to accurately simulate recent changes in primary productivity in Lake Michigan.

  20. Using occupancy modeling to compare traditional versus DNA metabarcoding methods for characterizing zooplankton biodiversity

    Science.gov (United States)

    DNA metabarcoding tools could increase our ability to detect changes in zooplankton communities and to detect invasive zooplankton taxa while they are still rare. Nonetheless, the use of DNA-metabarcoding for characterizing zooplankton biodiversity in the Great Lakes has not bee...

  1. Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

    Science.gov (United States)

    Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

    2016-06-01

    Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

  2. Implementation of the zooplankton functional response in plankton models: State of the art, recent challenges and future directions

    Science.gov (United States)

    Morozov, Andrew; Poggiale, Jean-Christophe; Cordoleani, Flora

    2012-09-01

    The conventional way of describing grazing in plankton models is based on a zooplankton functional response framework, according to which the consumption rate is computed as the product of a certain function of food (the functional response) and the density/biomass of herbivorous zooplankton. A large amount of literature on experimental feeding reports the existence of a zooplankton functional response in microcosms and small mesocosms, which goes a long way towards explaining the popularity of this framework both in mean-field (e.g. NPZD models) and spatially resolved models. On the other hand, the complex foraging behaviour of zooplankton (feeding cycles) as well as spatial heterogeneity of food and grazer distributions (plankton patchiness) across time and space scales raise questions as to the existence of a functional response of herbivores in vivo. In the current review, we discuss limitations of the ‘classical’ zooplankton functional response and consider possible ways to amend this framework to cope with the complexity of real planktonic ecosystems. Our general conclusion is that although the functional response of herbivores often does not exist in real ecosystems (especially in the form observed in the laboratory), this framework can be rather useful in modelling - but it does need some amendment which can be made based on various techniques of model reduction. We also show that the shape of the functional response depends on the spatial resolution (‘frame’) of the model. We argue that incorporating foraging behaviour and spatial heterogeneity in plankton models would not necessarily require the use of individual based modelling - an approach which is now becoming dominant in the literature. Finally, we list concrete future directions and challenges and emphasize the importance of a closer collaboration between plankton biologists and modellers in order to make further progress towards better descriptions of zooplankton grazing.

  3. Simulation Modeling of Zooplankton and Benthos in Reservoirs: Documentation and Development of Model Constructs.

    Science.gov (United States)

    1980-03-01

    additional food sources were available. 111. Porter (1973), who examined in situ the selective grazing of algae by a zooplankton community in Fuller Pond...large green algae increased. 112. Anabaena affinis and A. flos- aguae were rarely consumed by the zooplankton and were unaffected by increased grazing...grazing rates over the limited temperature range of 170 to 21*C. Nauwerck (1959), who conducted in situ experiments at Lake Erken, Sweden, with Daphnia

  4. Empirical relationships between phytoplankton and zooplankton biomass in Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.

    and temperature, zooplankton and phytoplankton, zooplankton and PO sub(4)-P and phytoplankton and PO sub(4)-P. Linear regression model is found to be significant at 1% level of significance. Since zooplankton and phytoplankton are significantly positively...

  5. Nonresonant Double Hopf Bifurcation in Toxic Phytoplankton-Zooplankton Model with Delay

    Science.gov (United States)

    Yuan, Rui; Jiang, Weihua; Wang, Yong

    This paper investigates a toxic phytoplankton-zooplankton model with Michaelis-Menten type phytoplankton harvesting. The model has rich dynamical behaviors. It undergoes transcritical, saddle-node, fold, Hopf, fold-Hopf and double Hopf bifurcation, when the parameters change and go through some of the critical values, the dynamical properties of the system will change also, such as the stability, equilibrium points and the periodic orbit. We first study the stability of the equilibria, and analyze the critical conditions for the above bifurcations at each equilibrium. In addition, the stability and direction of local Hopf bifurcations, and the completion bifurcation set by calculating the universal unfoldings near the double Hopf bifurcation point are given by the normal form theory and center manifold theorem. We obtained that the stable coexistent equilibrium point and stable periodic orbit alternate regularly when the digestion time delay is within some finite value. That is, we derived the pattern for the occurrence, and disappearance of a stable periodic orbit. Furthermore, we calculated the approximation expression of the critical bifurcation curve using the digestion time delay and the harvesting rate as parameters, and determined a large range in terms of the harvesting rate for the phytoplankton and zooplankton to coexist in a long term.

  6. Resource competition and an analytical model of zooplankton feeding on phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Smith, O L; Shugart, H H; O' Neill, R V; Booth, R S; McNaught, D C

    1975-01-01

    A new consumer-resource The model was developed with specific reference to zooplankton feeding on phytoplankton. In principle, the model can be extended to any terrestrial or aquatic community in which the consumers graze nearly randomly. It is assumed that the food as relatively little escape capabity. An attempt was made to derive the consumer-resource interaction term from first principles.A general form with clearly defined parameters that represent fundamental system processes such as consumer filtering rate. model parameters describes two known forms of feeding:(1): saturation feeding in which the rate remains constant above a given food density while the filtering rate decreases, and(2) inhibited feeding in which a decline appears at high food density. From an examination of the model's equilibrium equations for strongly similar zooplankton species feeding on similar phytoplankton species, the following conclusions were drawn. The competitive exclusion principle has only limited validity. For a community in which the consumers exhibit no intraspecific competition and have identical assimilation efficiency to death-rate ratios, e/d, any number of consumer species may, in fact, coexist and compete for the same food. The equations for a complex community composed of many consumer and food species can be reduced to a single equation with form identical to that of a single-consumer, single-food system. The standard competition coefficient, ..cap alpha.., of the Volterra equation is a poor measure of competition in nonlinear systems. It exhibits incongruous variations with changes in system parameters. In a community with no intraspecific competition, allcompetition coefficients are unity. In a community with intraspecific competition, the competition coefficients C/sub in/ tend to equalize as the number of food species increases, resulting in equal competitive strength of all consumer species in systems of the type studied.

  7. Magnetic Field Fluctuations Due to Diel Vertical Migrations of Zooplankton

    Science.gov (United States)

    Dean, C.; Soloviev, A.

    2016-12-01

    Dean et al. (2016) have indicated that at high zooplankton concentrations, diel vertical migrations (DVM) cause velocity fluctuations and a respective increase of the dissipation rate of turbulent kinetic energy (TKE). In this work, we used a 3D non-hydrostatic computational fluid dynamics model with Lagrangian particle injections (a proxy for migrating organisms) via a discrete phase model to simulate the effect of turbulence generation by DVM. We tested a range of organism concentrations from 1000 to 10,000 organisms/m3. The simulation at an extreme concentration of zooplankton showed an increase in dissipation rate of TKE by two to three orders of magnitude during DVM over background turbulence, 10-8 W kg-1. At lower concentrations (Frank, J. Wood, 2016: Biomixing due to diel vertical migrations of zooplankton. Ocean Modelling 98, 51-64.

  8. Development of a Method to Determine the Number of Viable Organisms or- 50 micrometers (Nominally Zooplankton) in Ships’ Ballast Water: A Combination of Two Vital, Fluorescent Stains

    Science.gov (United States)

    2010-04-23

    dimension: ≥ 50 µm (nominally zooplankton), ≥ 10 µm and < 50 µm (nominally protists ), and < 10 µm (nominally bacteria). The IMO convention specifies the... protists comprise a small – but consistently present – fraction of the organisms found in the ≥ 50 µm size class, and many of these protists do...38 to 325 organisms l-1 from July 2008 to July 2009, and the community was consistently dominated by crustaceans except during summer protist blooms

  9. Modelling the future biogeography of North Atlantic zooplankton communities in response to climate change

    KAUST Repository

    Villarino, E

    2015-07-02

    Advances in habitat and climate modelling allow us to reduce uncertainties of climate change impacts on species distribution. We evaluated the impacts of future climate change on community structure, diversity, distribution and phenology of 14 copepod species in the North Atlantic. We developed and validated habitat models for key zooplankton species using continuous plankton recorder (CPR) survey data collected at mid latitudes of the North Atlantic. Generalized additive models (GAMs) were applied to relate the occurrence of species to environmental variables. Models were projected to future (2080–2099) environmental conditions using coupled hydroclimatix–biogeochemical models under the Intergovernmental Panel on Climate Change (IPCC) A1B climate scenario, and compared to present (2001–2020) conditions. Our projections indicated that the copepod community is expected to respond substantially to climate change: a mean poleward latitudinal shift of 8.7 km per decade for the overall community with an important species range variation (–15 to 18 km per decade); the species seasonal peak is expected to occur 12–13 d earlier for Calanus finmarchicus and C. hyperboreus; and important changes in community structure are also expected (high species turnover of 43–79% south of the Oceanic Polar Front). The impacts of the change expected by the end of the century under IPCC global warming scenarios on copepods highlight poleward shifts, earlier seasonal peak and changes in biodiversity spatial patterns that might lead to alterations of the future North Atlantic pelagic ecosystem. Our model and projections are supported by a temporal validation undertaken using the North Atlantic climate regime shift that occurred in the 1980s: the habitat model built in the cold period (1970–1986) has been validated in the warm period (1987–2004).

  10. Modelling the future biogeography of North Atlantic zooplankton communities in response to climate change

    KAUST Repository

    Villarino, E; Chust, G; Licandro, P; Butenschö n, M; Ibaibarriaga, L; Larrañ aga, A; Irigoien, Xabier

    2015-01-01

    Advances in habitat and climate modelling allow us to reduce uncertainties of climate change impacts on species distribution. We evaluated the impacts of future climate change on community structure, diversity, distribution and phenology of 14 copepod species in the North Atlantic. We developed and validated habitat models for key zooplankton species using continuous plankton recorder (CPR) survey data collected at mid latitudes of the North Atlantic. Generalized additive models (GAMs) were applied to relate the occurrence of species to environmental variables. Models were projected to future (2080–2099) environmental conditions using coupled hydroclimatix–biogeochemical models under the Intergovernmental Panel on Climate Change (IPCC) A1B climate scenario, and compared to present (2001–2020) conditions. Our projections indicated that the copepod community is expected to respond substantially to climate change: a mean poleward latitudinal shift of 8.7 km per decade for the overall community with an important species range variation (–15 to 18 km per decade); the species seasonal peak is expected to occur 12–13 d earlier for Calanus finmarchicus and C. hyperboreus; and important changes in community structure are also expected (high species turnover of 43–79% south of the Oceanic Polar Front). The impacts of the change expected by the end of the century under IPCC global warming scenarios on copepods highlight poleward shifts, earlier seasonal peak and changes in biodiversity spatial patterns that might lead to alterations of the future North Atlantic pelagic ecosystem. Our model and projections are supported by a temporal validation undertaken using the North Atlantic climate regime shift that occurred in the 1980s: the habitat model built in the cold period (1970–1986) has been validated in the warm period (1987–2004).

  11. Biomass relations between phytoplankton and zooplankton in Goa waters

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  12. Current direction, zooplankton, wind wave spectra, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 18 October 1977 to 01 May 1979 (NODC Accession 7900270)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, zooplankton, benthic organisms, wind wave spectra, and other data were collected using moored current meter casts and other instruments in the...

  13. Chemical, phytoplankton, zooplankton, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1981-02-12 to 1982-01-05 (NODC Accession 8200064)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical, phytoplankton, benthic organisms, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  14. Current direction, zooplankton, phytoplankton, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 17 February 1981 - 22 June 1982 (NODC Accession 8200230)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, phytoplankton, zooplankton, benthic organisms, and other data were collected using moored current meter casts and other instruments in the Gulf of...

  15. Chemical, benthic organisms, zooplankton, marine toxic substances, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1979-08-30 to 1981-09-21 (NODC Accession 8200012)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical, marine toxic substances, benthic organisms, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf...

  16. A coupled oscillator model describes normal and strange zooplankton swimming behaviour

    NARCIS (Netherlands)

    Ringelberg, J.; Lingeman, R.

    2003-01-01

    "Normal" swimming in marine and freshwater zooplankton is often intermittent with active upward and more passive downward displacements. In the freshwater cladoceran Daphnia, the pattern is sometimes regular enough to demonstrate the presence of a rhythm. Abnormal swimming patterns were also

  17. Surface metal adsorption on zooplankton carapaces: implications for exposure and effects in consumer organisms

    International Nuclear Information System (INIS)

    Robinson, K.A.; Baird, D.J.; Wrona, F.J.

    2003-01-01

    Metals adsorbed to prey surfaces may be a mechanism of exposure in predators. - The current study aimed to determine the potential of two important aquatic invertebrate crustacean species, Daphnia magna and Ceriodaphnia dubia, to adsorb cadmium on to their carapaces from aqueous solution. Using the Langmuir equation to model data outputs, it was shown that cadmium readily became associated with the carapace surfaces of both species, with uptake being dependent on exposure time and concentration. Maximum carapace-adsorption potential was found to be directly related to surface area, so that at predicted carapace saturation, D. magna neonates bound approximately five times more cadmium than the smaller C. dubia neonates. However, adsorption per unit surface area was found to be similar under the same exposure conditions. Results of surface metal adsorption studies in C. dubia suggested that short term exposures to high concentrations of aqueous cadmium would lead to similar levels of adsorption as obtained with long-term exposures to low concentrations. The study illustrates that contaminants adsorbed to prey surfaces may be an important mechanism of exposure to predators, and highlights some potential problems of feeding organisms during long-term toxicity tests

  18. Zooplankton abundance of the Andaman sea

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Achuthankutty, C.T.; Nair, S.R.S.; Nair, V.R.

    the dominant component followed by Chaetognatha and Tunicata Estimates of zooplankton biomass to dry weight and to organic carbon content are made. The average standing crop of zooplankton is 288.8 mg C m2 for the upper 200 m column...

  19. Zooplankton as an early warning system of persistent organic pollutants contamination in a deep lake (lake Iseo, Northern Italy

    Directory of Open Access Journals (Sweden)

    Silvia Quadroni

    2012-07-01

    Full Text Available The lake Iseo has been recently contaminated by DDT residues, originated from the melting of a glacier that released the pollutants accumulated in the past. Because of this recent input, DDT residues concentrations rose more quickly in zooplankton than in fish during 2009. In autumn 2010 the ratio drastically dropped to one–two for all the compounds indicating that the glacial DDT load should have been ceased. The situation was different for PCBs that were released to a much lower extent from glaciers. The PCB 138 ratio between zooplankton and fish was always around one–two in both years. As the zooplankton response to pollution changes resulted particularly prompt, our research highlights the importance of this component as an early warning bioindicator of hydrophobic pollutants.

  20. Null models for study Rotifers and Crustaceans Zooplankton species richness in Chilean Patagonian lakes

    OpenAIRE

    Escalante, Patricio de los Ríos

    2016-01-01

    Abstract Aims The Patagonian lakes are characterized by their oligotrophy that is the cause of low species number in their zooplankton assemblage. The aim of the present study is to analyze the crustacean and rotifers species number pattern in Patagonian lakes among a latitudinal gradient (40-51 °S). Results The results revealed that there are direct significant correlations between total species with rotifer species, and chlorophyll concentration with crustacean species number, and an inve...

  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

    Roč. 186, MAR (2014), s. 115-125 ISSN 0269-7491 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA ČR 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. Zooplankton assemblage of Oyun Reservoir, Offa, Nigeria.

    Science.gov (United States)

    Mustapha, Moshood K

    2009-12-01

    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 zooplankton 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.

  3. Zooplankton mortality in 3D ecosystem modelling considering variable spatial–temporal fish consumptions in the North Sea

    DEFF Research Database (Denmark)

    Maar, Marie; Rindorf, Anna; Møller, Eva Friis

    2014-01-01

    We tested the feasibility of imposing mesozooplankton mortality into a 3D model based on estimated consumption rates of the dominant planktivorous fish in the North Sea-Kattegat area. The spatial biomass distribution of Atlantic herring (Clupea harengus), horse mackerel (Trachurus trachurus....... The fish larvae grazing pressure was obtained from a spatial, size-based larval community model. In this model, larvae, herring and sandeel were the most important fish predators on mesozooplankton, but these groups had different spatial and temporal (seasonal) distributions. Fish larvae were particularly......, production and mortality. In the present study, the index was kept relatively simple and can be further developed with respect to the description of fish as well carnivorous zooplankton ingestion rates. The data input required to create the fish index is i) planktivorous fish stock biomasses and ii) relative...

  4. Application of an automatic approach to calibrate the NEMURO nutrient-phytoplankton-zooplankton food web model in the Oyashio region

    Science.gov (United States)

    Ito, Shin-ichi; Yoshie, Naoki; Okunishi, Takeshi; Ono, Tsuneo; Okazaki, Yuji; Kuwata, Akira; Hashioka, Taketo; Rose, Kenneth A.; Megrey, Bernard A.; Kishi, Michio J.; Nakamachi, Miwa; Shimizu, Yugo; Kakehi, Shigeho; Saito, Hiroaki; Takahashi, Kazutaka; Tadokoro, Kazuaki; Kusaka, Akira; Kasai, Hiromi

    2010-10-01

    The Oyashio region in the western North Pacific supports high biological productivity and has been well monitored. We applied the NEMURO (North Pacific Ecosystem Model for Understanding Regional Oceanography) model to simulate the nutrients, phytoplankton, and zooplankton dynamics. Determination of parameters values is very important, yet ad hoc calibration methods are often used. We used the automatic calibration software PEST (model-independent Parameter ESTimation), which has been used previously with NEMURO but in a system without ontogenetic vertical migration of the large zooplankton functional group. Determining the performance of PEST with vertical migration, and obtaining a set of realistic parameter values for the Oyashio, will likely be useful in future applications of NEMURO. Five identical twin simulation experiments were performed with the one-box version of NEMURO. The experiments differed in whether monthly snapshot or averaged state variables were used, in whether state variables were model functional groups or were aggregated (total phytoplankton, small plus large zooplankton), and in whether vertical migration of large zooplankton was included or not. We then applied NEMURO to monthly climatological field data covering 1 year for the Oyashio, and compared model fits and parameter values between PEST-determined estimates and values used in previous applications to the Oyashio region that relied on ad hoc calibration. We substituted the PEST and ad hoc calibrated parameter values into a 3-D version of NEMURO for the western North Pacific, and compared the two sets of spatial maps of chlorophyll- a with satellite-derived data. The identical twin experiments demonstrated that PEST could recover the known model parameter values when vertical migration was included, and that over-fitting can occur as a result of slight differences in the values of the state variables. PEST recovered known parameter values when using monthly snapshots of aggregated

  5. Allochthonous subsidies of organic matter across a lake-river-fjord landscape in the Chilean Patagonia: Implications for marine zooplankton in inner fjord areas

    Science.gov (United States)

    Vargas, Cristian A.; Martinez, Rodrigo A.; San Martin, Valeska; Aguayo, Mauricio; Silva, Nelson; Torres, Rodrigo

    2011-03-01

    Ecosystems can act as both sources and sinks of allochthonous nutrients and organic matter. In this sense, fjord ecosystems are a typical interface and buffer zone between freshwater systems, glaciated continents, and the coastal ocean. In order to evaluate the potential sources and composition of organic matter across fjord ecosystems, we characterized particulate organic matter along a lake-river-fjord corridor in the Chilean Patagonia using stable isotope (δ 13C) and lipid (fatty acid composition) biomarker analyses. Furthermore, estimates of zooplankton carbon ingestion rates and measurements of δ 13C and δ 15N in zooplankton (copepods) were used to evaluate the implications of allochthonous subsidies for copepods inhabiting inner fjord areas. Our results showed that riverine freshwater flows contributed an important amount of dissolved silicon but, scarce nitrate and phosphate to the brackish surface layer of the fjord ecosystem. Isotopic signatures of particulate organic matter from lakes and rivers were distinct from their counterparts in oceanic influenced stations. Terrestrial allochthonous sources could support around 68-86% of the particulate organic carbon in the river plume and glacier melting areas, whereas fatty acid concentrations were maximal in the surface waters of the Pascua and Baker river plumes. Estimates of carbon ingestion rates and δ 13C in copepods from the river plume areas indicated that terrestrial carbon could account for a significant percentage of the copepod body carbon (20-50%) during periods of food limitation. Particulate organic matter from the Pascua River showed a greater allochthonous contribution of terrigenous/vascular plant sources. Rivers may provide fjord ecosystems with allochthonous contributions from different sources because of the distinct vegetation coverage and land use along each river's watershed. These observations have significant implications for the management of local riverine areas in the context of

  6. Zooplankton and fisheries

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    is dominatEd. by herbivores. Zooplankton constitutes the main food item of several economic important animals. The pelagic fishes migrate in shoals to the feeding ground rich in food and hence zooplankton are used as indicators of rich potential fishing...

  7. Trait-based approaches to zooplankton communities

    DEFF Research Database (Denmark)

    Lichtman, E.; Ohman, M.D.; Kiørboe, Thomas

    2013-01-01

    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......; 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......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...

  8. Numerical studies of the influence of food ingestion on phytoplankton and zooplankton biomasses

    Directory of Open Access Journals (Sweden)

    Lidia Dzierzbicka-G³owacka

    2002-03-01

    Full Text Available This paper presents the numerical simulations of the influence of food ingestion by a herbivorous copepod on phytoplankton and zooplankton biomasses (PZB in the sea. The numerical studies were carried out using the phytoplankton-zooplankton-nutrient-detritus PhyZooNuDe biological upper layer model. This takes account both of fully developed primary production and regeneration mechanisms and of daily migration of zooplankton. In this model the zooplankton is treated not as a 'biomass' but as organisms having definite patterns of growth, reproduction and mortality. Assuming also that {Zoop} is composed ofi cohorts of copepods with weights Wi and numbers Zi, then {Zoop} = WiZi. The PhyZooNuDe model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton, zooplankton and nutrients, and one ordinary first-order differential equation for the benthic detritus pool, together with initial and boundary conditions. The calculations were made during 90 days (April, May and June for the study area P1 (Gdansk Deep in an area 0z<=20 m with a vertical space step of 0.1 m and a time step of 300 s. The simulation given here demonstrated the importance of food ingestion by zooplankton in that it can alter the nature of the interactions of plants and herbivores. The analysis of these numerical studies indicate that the maximal ingestion rate and the half-saturation constant for grazing strongly affect the magnitude of the spring bloom and the cyanobacterial bloom, and also the total zooplankton biomass.

  9. Bifurcation and Control in a Singular Phytoplankton-Zooplankton-Fish Model with Nonlinear Fish Harvesting and Taxation

    Science.gov (United States)

    Meng, Xin-You; Wu, Yu-Qian

    In this paper, a delayed differential algebraic phytoplankton-zooplankton-fish model with taxation and nonlinear fish harvesting is proposed. In the absence of time delay, the existence of singularity induced bifurcation is discussed by regarding economic interest as bifurcation parameter. A state feedback controller is designed to eliminate singularity induced bifurcation. Based on Liu’s criterion, Hopf bifurcation occurs at the interior equilibrium when taxation is taken as bifurcation parameter and is more than its corresponding critical value. In the presence of time delay, by analyzing the associated characteristic transcendental equation, the interior equilibrium loses local stability when time delay crosses its critical value. What’s more, the direction of Hopf bifurcation and stability of the bifurcating periodic solutions are investigated based on normal form theory and center manifold theorem, and nonlinear state feedback controller is designed to eliminate Hopf bifurcation. Furthermore, Pontryagin’s maximum principle has been used to obtain optimal tax policy to maximize the benefit as well as the conservation of the ecosystem. Finally, some numerical simulations are given to demonstrate our theoretical analysis.

  10. 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...

  11. The use of mechanistic descriptions of algal growth and zooplankton grazing in an estuarine eutrophication model

    Science.gov (United States)

    Baird, M. E.; Walker, S. J.; Wallace, B. B.; Webster, I. T.; Parslow, J. S.

    2003-03-01

    A simple model of estuarine eutrophication is built on biomechanical (or mechanistic) descriptions of a number of the key ecological processes in estuaries. Mechanistically described processes include the nutrient uptake and light capture of planktonic and benthic autotrophs, and the encounter rates of planktonic predators and prey. Other more complex processes, such as sediment biogeochemistry, detrital processes and phosphate dynamics, are modelled using empirical descriptions from the Port Phillip Bay Environmental Study (PPBES) ecological model. A comparison is made between the mechanistically determined rates of ecological processes and the analogous empirically determined rates in the PPBES ecological model. The rates generally agree, with a few significant exceptions. Model simulations were run at a range of estuarine depths and nutrient loads, with outputs presented as the annually averaged biomass of autotrophs. The simulations followed a simple conceptual model of eutrophication, suggesting a simple biomechanical understanding of estuarine processes can provide a predictive tool for ecological processes in a wide range of estuarine ecosystems.

  12. Current direction, benthic organisms, zooplankton, chemical, toxis substances, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1981-03-24 to 1982-02-19 (NODC Accession 8200129)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, zooplankton, chemical, toxic substances, and other data were collected using moored current meter casts and other instruments...

  13. Numerical studies of the influence of food ingestion on phytoplankton and zooplankton biomasses

    OpenAIRE

    Lidia Dzierzbicka-G³owacka

    2002-01-01

    This paper presents the numerical simulations of the influence of food ingestion by a herbivorous copepod on phytoplankton and zooplankton biomasses (PZB) in the sea. The numerical studies were carried out using the phytoplankton-zooplankton-nutrient-detritus PhyZooNuDe biological upper layer model. This takes account both of fully developed primary production and regeneration mechanisms and of daily migration of zooplankton. In this model the zooplankton is treated not as a 'biomass' but as ...

  14. Zooplankton body composition

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2013-01-01

    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 composition and argue that differences in feeding mechanisms and predator avoidance strategies favor either......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...... a watery or a condensed body form, and that in the intermediate taxa the moderately elevated water content is related to buoyancy control and ambush feeding...

  15. Seasonal succession in zooplankton feeding traits reveals trophic trait coupling

    DEFF Research Database (Denmark)

    Kenitz, Kasia; Visser, Andre; Mariani, Patrizio

    2017-01-01

    non-motile cells flourishing in spring and motile community dominating during summer. The zooplankton community is dominated by active feeding-current feeders with peak biomass in the late spring declining during summer. The model reveals how zooplankton grazing reinforces protist plankton seasonal...

  16. Analyzing the trophic link between the mesopelagic microbial loop and zooplankton from observed depth profiles of bacteria and protozoa

    Directory of Open Access Journals (Sweden)

    T. Tanaka

    2005-01-01

    Full Text Available It is widely recognized that organic carbon exported to the ocean aphotic layer is significantly consumed by heterotrophic organisms such as bacteria and zooplankton in the mesopelagic layer. However, very little is known for the trophic link between bacteria and zooplankton or the function of the microbial loop in this layer. In the northwestern Mediterranean, recent studies have shown that viruses, bacteria, heterotrophic nanoflagellates, and ciliates distribute down to 2000 m with group-specific depth-dependent decreases, and that bacterial production decreases with depth down to 1000 m. Here we show that such data can be analyzed using a simple steady-state food chain model to quantify the carbon flow from bacteria to zooplankton over the mesopelagic layer. The model indicates that bacterial mortality by viruses is similar to or 1.5 times greater than that by heterotrophic nanoflagellates, and that heterotrophic nanoflagellates transfer little of bacterial production to higher trophic levels.

  17. Zooplankton ecology of the mangrove habitats of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    and fish larvae constituted bulk of zooplankton. Majority of these organisms were stragglers. The zooplankters showing better eco-physiological adaptations colonized in pools surroundEd. by thick mangroves vegetation...

  18. Carbon export by vertically migrating zooplankton

    DEFF Research Database (Denmark)

    Hansen, Agnethe Nøhr; Visser, André W.

    2016-01-01

    Through diel vertical migration (DVM), zooplankton add an active transport to the otherwise passive sinking of detrital material that constitutes the biological pump. This active transport has proven difficult to quantify. We present a model that estimates both the temporal and depth characterist...... is transported than at either equatorial or boreal latitudes. We estimate that the amount of carbon transported below the mixed layer by migrating zooplankton in the North Atlantic Ocean constitutes 27% (16–30%) of the total export flux associated with the biological pump in that region...

  19. Isolating Tracers of Phytoplankton with Allometric Zooplankton (TOPAZ) from Modular Ocean Model (MOM5) to Couple it with a Global Ocean Model

    Science.gov (United States)

    Jung, H. C.; Moon, B. K.; Wie, J.; Park, H. S.; Kim, K. Y.; Lee, J.; Byun, Y. H.

    2017-12-01

    This research is motivated by a need to develop a new coupled ocean-biogeochemistry model, a key tool for climate projections. The Modular Ocean Model (MOM5) is a global ocean/ice model developed by the Geophysical Fluid Dynamics Laboratory (GFDL) in the US, and it incorporates Tracers of Phytoplankton with Allometric Zooplankton (TOPAZ), which simulates the marine biota associated with carbon cycles. We isolated TOPAZ from MOM5 into a stand-alone version (TOPAZ-SA), and had it receive initial data and ocean physical fields required. Then, its reliability was verified by comparing the simulation results from the TOPAZ-SA with the MOM5/TOPAZ. This stand-alone version of TOPAZ is to be coupled to the Nucleus for European Modelling of the Ocean (NEMO). Here we present the preliminary results. Acknowledgements This research was supported by the project "Research and Development for KMA Weather, Climate, and Earth system Services" (NIMS-2016-3100) of the National Institute of Meteorological Sciences/Korea Meteorological Administration.

  20. Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web

    Energy Technology Data Exchange (ETDEWEB)

    Pickhardt, Paul C. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States)]. E-mail: paul.pickhardt@stonybrook.edu; Folt, Carol L. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States); Chen, Celia Y. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States); Klaue, Bjoern [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Blum, Joel D. [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2005-03-01

    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 (CH{sub 3} {sup 200}HgCl) and inorganic ({sup 201}HgCl{sub 2}) 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 (Hg{sub I}) in seston from low nutrient mesocosms, there were no significant differences in the Hg{sub I} 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 {approx}18% of the CH{sub 3} {sup 200}Hg and {approx}33% of the {sup 201}Hg added. Results from our experiments

  1. Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web

    International Nuclear Information System (INIS)

    Pickhardt, Paul C.; Folt, Carol L.; Chen, Celia Y.; Klaue, Bjoern; Blum, Joel D.

    2005-01-01

    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 (CH 3 200 HgCl) and inorganic ( 201 HgCl 2 ) 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 (Hg I ) in seston from low nutrient mesocosms, there were no significant differences in the Hg I 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 CH 3 200 Hg and ∼33% of the 201 Hg added. Results from our experiments corroborate results from field studies and suggest the

  2. Pilot Study on Potential Impacts of Fisheries-Induced Changes in Zooplankton Mortality on Marine Biogeochemistry

    Science.gov (United States)

    Getzlaff, Julia; Oschlies, Andreas

    2017-11-01

    In this pilot study we link the yield of industrial fisheries to changes in the zooplankton mortality in an idealized way accounting for different target species (planktivorous fish—decreased zooplankton mortality; large predators—increased zooplankton mortality). This indirect approach is used in a global coupled biogeochemistry circulation model to estimate the range of the potential impact of industrial fisheries on marine biogeochemistry. The simulated globally integrated response on phytoplankton and primary production is in line with expectations—a high (low) zooplankton mortality results in a decrease (increase) of zooplankton and an increase (decrease) of phytoplankton. In contrast, the local response of zooplankton and phytoplankton depends on the region under consideration: In nutrient-limited regions, an increase (decrease) in zooplankton mortality leads to a decrease (increase) in both zooplankton and phytoplankton biomass. In contrast, in nutrient-replete regions, such as upwelling regions, we find an opposing response: an increase (decrease) of the zooplankton mortality leads to an increase (decrease) in both zooplankton and phytoplankton biomass. The results are further evaluated by relating the potential fisheries-induced changes in zooplankton mortality to those driven by CO2 emissions in a business-as-usual 21st century emission scenario. In our idealized case, the potential fisheries-induced impact can be of similar size as warming-induced changes in marine biogeochemistry.

  3. Assessment of power-plant effects on zooplankton in the near field

    International Nuclear Information System (INIS)

    Polgar, T.T.; Bongers, L.H.; Krainak, G.M.

    1976-01-01

    With the use of a simple entrainment model that takes into account tidal recirculation, mixing, and once-through kill rate, theoretical expressions are derived for ratios of densities of live organisms at the intake of a power plant to densities in the far field. Experimental data on the abundances of dead and live stages of Eurytemora affinis and Acartia tonsa are used to compare to model results. A study of the entrainment of zooplankton near the intake of the Morgantown power plant and a concurrent study of the distribution of zooplankton in the Potomac River provided the biological data. Physical information was derived from extensive hydrographic measurements. Comparing experimental data with model predictions showed that radical depletions occurred in the naupliar stages near the plant site which cannot be accounted for by cooling-system or delayed entrainment mortalities. These near-field changes are attributed to avoidance reactions and to mortalities in the vicinity of the plant

  4. Simulation of annual cycles of phytoplankton, zooplankton and nutrients using a mixed layer model coupled with a biological model

    OpenAIRE

    Troupin, Charles

    2006-01-01

    In oceanography, the mixed layer refers to the near surface part of the water column where physical and biological variables are distributed quasi homogeneously. Its depth depends on conditions at the air-sea interface (heat and freshwater fluxes, wind stress) and on the characteristics of the flow (stratification, shear), and has a strong influence on biological dynamics. The aim of this work is to model the behaviour of the mixed layer in waters situated to the south of Gr...

  5. Zooplankton community composition of high mountain lakes in the Tatra Mts., the Alps in North Tyrol, and Scotland: relationship to pH, depth, organic carbon, and chlorophyll-a concentration

    Directory of Open Access Journals (Sweden)

    Skála Ivan

    2015-10-01

    Full Text Available The European EMERGE (European Mountain lake Ecosystems: Regionalisation, diaGnostic & socio-economic Evaluation project was a survey of high mountain lakes (above treeline across Europe using unified methods of sampling and analysis. The sampling was carried out in summer or autumn 2000, and comprised biological samples, and samples for chemical analysis. Data from three lake districts are used in this paper: the Tatra Mts. in Slovakia and Poland (45 lakes, the Alps in Tyrol in Austria (22 lakes, and Scotland (30 lakes. As it is shown by multiple regression analysis, DTOC (dissolved or total organic carbon is the key variable for most groups of zooplankton. With increasing DTOC and mostly with chlorophyll-a decreasing, pH increasing and depth decreasing, macrofitrators with coarse filter meshes are replaced by microfiltrators with fine filter meshes. Higher DTOC may increase bacterioplankton production and advantage species able to consume bacteria (microfiltrators. Other zooplankton species also differ in their preference for DTOC, chlorophyll-a, pH and depth, but DTOC being positively correlated with chlorophyll-a and pH positively correlated with depth. It may be caused by their different preference for food quality in terms of C:P ratio.

  6. US AMLR Program zooplankton dataset

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton research in the US AMLR Program focuses on the link between prey production, availability, and climate variability in relation to predator and fishery...

  7. Biomass and biochemical composition of zooplankton from northwest Bay of Bengal during January 1990

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Goswami, S.C.

    Biomass, proximate composition, organic carbon and calorie content of assorted zooplankton from the surface waters were studied. Day and night stations revealed significant difference in biomass (displacement volume, dry wt and organic carbon...

  8. Zooplankton assemblage of Oyun Reservoir, Offa, Nigeria

    Directory of Open Access Journals (Sweden)

    Moshood K Mustapha

    2009-12-01

    Full Text Available 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 zooplankton 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.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 zooplancton: 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

  9. Discrete dynamical model of mechanisms determining the relations of biodiversity and stability at different levels of organization of living matter

    OpenAIRE

    Kabalyants, Petr; Nosov, Konstantin; Bespalov, Yuri

    2017-01-01

    The paper aims at building the model of relations of biodiversity and stability at different levels of organization of living matter with the use of discrete dynamical models. The relations revealed in the study are illustrated by case studies of zooplankton community of the eutrophicated lake and the colorimetric parameters of the microalgae community of phytobenthos and phytoperiphyton. The results offer: (1) new approaches to estimating the risk of mass development of toxic cyanobacteria i...

  10. Zooplankton variability in the Zuari estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Achuthankutty, C.T.; Nair, S.R.S.

    Short term variability in the secondary production and composition of zooplankton were studied during February to March 1979 by collecting zooplankton every alternate day from a station located near the mouth of Zuari. Irregularity in the production...

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

    DEFF Research Database (Denmark)

    Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín

    2016-01-01

    zooplankton community, despite iron limitation of phytoplankton community growth rates. 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....

  12. Planktivory in the changing Lake Huron zooplankton community: Bythotrephes consumption exceeds that of Mysis and fish

    Science.gov (United States)

    Bunnell, D.B.; Hunter, R. Douglas; Warner, D.M.; Chriscinske, M.A.; Roseman, E.F.

    2011-01-01

    Oligotrophic lakes are generally dominated by calanoid copepods because of their competitive advantage over cladocerans at low prey densities. Planktivory also can alter zooplankton community structure. We sought to understand the role of planktivory in driving recent changes to the zooplankton community of Lake Huron, a large oligotrophic lake on the border of Canada and the United States. We tested the hypothesis that excessive predation by fish (rainbow smelt Osmerus mordax, bloater Coregonus hoyi) and invertebrates (Mysis relicta, Bythotrephes longimanus) had driven observed declines in cladoceran and cyclopoid copepod biomass between 2002 and 2007. We used a field sampling and bioenergetics modelling approach to generate estimates of daily consumption by planktivores at two 91-m depth sites in northern Lake Huron, U.S.A., for each month, May-October 2007. Daily consumption was compared to daily zooplankton production. Bythotrephes was the dominant planktivore and estimated to have eaten 78% of all zooplankton consumed. Bythotrephes consumption exceeded total zooplankton production between July and October. Mysis consumed 19% of all the zooplankton consumed and exceeded zooplankton production in October. Consumption by fish was relatively unimportant - eating only 3% of all zooplankton consumed. Because Bythotrephes was so important, we explored other consumption estimation methods that predict lower Bythotrephes consumption. Under this scenario, Mysis was the most important planktivore, and Bythotrephes consumption exceeded zooplankton production only in August. Our results provide no support for the hypothesis that excessive fish consumption directly contributed to the decline of cladocerans and cyclopoid copepods in Lake Huron. Rather, they highlight the importance of invertebrate planktivores in structuring zooplankton communities, especially for those foods webs that have both Bythotrephes and Mysis. Together, these species occupy the epi-, meta- and

  13. 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; Agustī, 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.

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

    Directory of Open Access Journals (Sweden)

    Ali M Al-Aidaroos

    Full Text Available 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.

  15. 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...

  16. Zooplankton in the Arctic outflow

    Science.gov (United States)

    Soloviev, K. A.; Dritz, A. V.; Nikishina, A. B.

    2009-04-01

    Climate changes in the Arctic cause the changes in the current system that may have cascading effect on the structure of plankton community and consequently on the interlinked and delicately balanced food web. Zooplankton species are by definition incapable to perform horizontal moving. Their transport is connected with flowing water. There are zooplankton species specific for the definite water masses and they can be used as markers for the different currents. That allows us to consider zooplankton community composition as a result of water mixing in the studied area. Little is known however about the mechanisms by which spatial and temporal variability in advection affect dynamics of local populations. Ice conditions are also very important in the function of pelagic communities. Melting time is the trigger to all "plankton blooming" processes, and the duration of ice-free conditions determines the food web development in the future. Fram Strait is one of the key regions for the Arctic: the cold water outflow comes through it with the East Greenland Current and meets warm Atlantic water, the West Spitsbergen Current, producing complicated hydrological situation. During 2007 and 2008 we investigated the structure functional characteristics of zooplankton community in the Fram Strait region onboard KV "Svalbard" (April 2007, April and May 2008) and RV "Jan Mayen" (May 2007, August 2008). This study was conducted in frame of iAOOS Norway project "Closing the loop", which, in turn, was a part of IPY. During this cruises multidisciplinary investigations were performed, including sea-ice observations, CTD and ADCP profiling, carbon flux, nutrients and primary production measurements, phytoplankton sampling. Zooplankton was collected with the Hydro-Bios WP2 net and MultiNet Zooplankton Sampler, (mouth area 0.25 m2, mesh size 180 um).Samples were taken from the depth strata of 2000-1500, 1500-1000, 1000-500,500-200, 200-100, 100-60, 60-30, 30-0 m. Gut fluorescence

  17. 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.

  18. Efectos del herbicida Paraquat sobre el zooplancton Effects of Paraquat herbicide on zooplankton

    Directory of Open Access Journals (Sweden)

    Ana María Gagneten

    2002-09-01

    Full Text Available The effects of 0.1; 0.2; 0.4 and 0.8 mlPQ/L were analized on a zooplankton community, to determine the most sensitive species and to analize the occurence of physical abnormalities. A total of 40 taxa were determined. Paraquat affected significantly the zooplankton density but not the species richness. A progressive state of deformation of these organisms was also observed. Paraquat showed to be highly toxic for the zooplankton, so this herbicide should be strictly regulated in aquatic and terrestrial ecosystems.

  19. ZOOPLANKTON FAUNA OF BİNGÖL FLOATING ISLANDS IN WINTER SEASON

    OpenAIRE

    Şen Özdemir, Nurgül; Caf, Fatma

    2015-01-01

    In this study was carried out winter season in 2011; zooplankton faunaof the Bingol Floating Islands. To­tally 18 zooplankton species were determinedas fol­lows; 14 Rotifera, 3 Cladocera and 1 Copepoda. It was determined thatthis zooplanktonic organisms consist­ed of 87.74 % Rotifera, 6.83 % Cladocera, and3.36 %  copepodit stages, 2.07 %  nauplii of copepoda. Rotif­era were thedominant group with regard to both spe­cies numbers, and individual numbers ofspecies. Cy­clops vicinus from Copepoda...

  20. Struktur Komunitas Zooplankton di Bendungan Telaga Tunjung, Kabupaten Tabanan-Bali

    Directory of Open Access Journals (Sweden)

    Ni Wayan Desy Wahyudiati

    2017-05-01

    Full Text Available Zooplankton are the heterotroph aquatic organisms and has a week swimming. Zooplankton acts as the first consumer in the waters, which utilize phytoplankton as their food. This research located in Telaga Tunjung reservoir, Timpag Village, Kerambitan Subdistrict, Tabanan Regency. The reservoir is used for industry, irrigation and tourism development. The aim of the research was to determine the community structure of zooplankton in Telaga Tunjung reservoir. This research was conducted from January to February 2016. Water sampling was conducted twice with a sampling interval of 2 weeks in 4 stations. There was a total of 23 species of zooplankton found, consisting of 6 classes: Eurotatoria (8 genera, Ciliatea (1 genera, Branchiopoda (4 genera, Monogononta (1 genera, Tubulinea (1 genera and Maxillopoda (3 genera. The most common species of zooplankton found in the sampling station were Polyarthra vulgaris (3.04 ind/l, Anuraeopsis coelata (1.28 ind/l, Keratella valga (0.43 ind/l, Vorticella sp. (0.49 ind/l, Diaphanosoma brachyurum (0.28 ind/l, Nauplius sp. (0.16 ind/l and Megacyclops viridis (1.16 ind/l. The average abundance of zooplankton was 9.38 ind/l. Based on the abundance of zooplankton, the trophic status of Telaga Tunjung reservoir is mesotrophic.

  1. 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...

  2. Potential acidification impacts on zooplankton in CCS leakage scenarios

    International Nuclear Information System (INIS)

    Halsband, Claudia; Kurihara, Haruko

    2013-01-01

    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 CO 2 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 CO 2 /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

  3. 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.

  4. Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency

    OpenAIRE

    Taipale, Sami J.; Galloway, Aaron W. E.; Aalto, Sanni L.; Kahilainen, Kimmo K.; Strandberg, Ursula; Kankaala, Paula

    2016-01-01

    Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. Here we show that during phytoplankton deficiency, zooplankton (Daphnia magna) can benefit from terrestrial particulate organic matter by using terr...

  5. Danger of zooplankton feeding

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, H.; Colin, S.P.

    2010-01-01

    and therefore perform occasional upward repositioning jumps. We quantified the fluid disturbance generated by repositioning jumps in a millimetre-sized copepod (Re ∼ 40). The kick of the swimming legs generates a viscous vortex ring in the wake; another ring of similar intensity but opposite rotation is formed...... around the decelerating copepod. A simple analytical model, that of an impulsive point force, properly describes the observed flow field as a function of the momentum of the copepod, including the translation of the vortex and its spatial extension and temporal decay. We show that the time-averaged fluid...

  6. Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency.

    Science.gov (United States)

    Taipale, Sami J; Galloway, Aaron W E; Aalto, Sanni L; Kahilainen, Kimmo K; Strandberg, Ursula; Kankaala, Paula

    2016-08-11

    Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. Here we show that during phytoplankton deficiency, zooplankton (Daphnia magna) can benefit from terrestrial particulate organic matter by using terrestrial-origin carbohydrates for energy and sparing essential fatty acids and amino acids for somatic growth and reproduction. Assimilated terrestrial-origin fatty acids from shoreline reed particles exceeded available diet, indicating that Daphnia may convert a part of their dietary carbohydrates to saturated fatty acids. This conversion was not observed with birch leaf diets, which had lower carbohydrate content. Subsequent analysis of 21 boreal and subarctic lakes showed that diet of herbivorous zooplankton is mainly based on high-quality phytoplankton rich in essential polyunsaturated fatty acids. The proportion of low-quality diets (bacteria and terrestrial particulate organic matter) was <28% of the assimilated carbon. Taken collectively, the incorporation of terrestrial carbon into zooplankton was not directly related to the concentration of terrestrial organic matter in experiments or lakes, but rather to the low availability of phytoplankton.

  7. Ecology of selected marine communities in Glacier Bay: Zooplankton, forage fish, seabirds and marine mammals

    Science.gov (United States)

    Robards, Martin D.; Drew, Gary S.; Piatt, John F.; Anson, Jennifer Marie; Abookire, Alisa A.; Bodkin, James L.; Hooge, Philip N.; Speckman, Suzann G.

    2003-01-01

    We studied oceanography (including primary production), secondary production, small schooling fish (SSF), and marine bird and mammal predators in Glacier Bay during 1999 and 2000. Results from these field efforts were combined with a review of current literature relating to the Glacier Bay environment. Since the conceptual model developed by Hale and Wright (1979) ‘changes and cycles’ continue to be the underlying theme of the Glacier Bay ecosystem. We found marked seasonality in many of the parameters that we investigated over the two years of research, and here we provide a comprehensive description of the distribution and relative abundance of a wide array of marine biota. Glacier Bay is a tidally mixed estuary that leads into basins, which stratify in summer, with the upper arms behaving as traditional estuaries. The Bay is characterized by renewal and mixing events throughout the year, and markedly higher primary production than in many neighboring southeast Alaska fjords (Hooge and Hooge, 2002). Zooplankton diversity and abundance within the upper 50 meters of the water column in Glacier Bay is similar to communities seen throughout the Gulf of Alaska. Zooplankton in the lower regions of Glacier Bay peak in abundance in late May or early June, as observed at Auke Bay and in the Gulf of Alaska. The key distinction between the lower Bay and other estuaries in the Gulf of Alaska is that a second smaller peak in densities occurs in August. The upper Bay behaved uniformly in temporal trends, peaking in July. Densities had begun to decline in August, but were still more than twice those observed in that region in May. The highest density of zooplankton observed was 17,870 organisms/m3 in Tarr Inlet during July. Trends in zooplankton community abundance and diversity within the lower Bay were distinct from upper-Glacier Bay trends. Whereas the lower Bay is strongly influenced by Gulf of Alaska processes, local processes are the strongest influence in the upper

  8. Diel vertical migration of zooplankton in the Tanzanian waters of ...

    African Journals Online (AJOL)

    The diel vertical migration of zooplankton was studied in the Southern part of Lake Victoria in January and July 2002. A van dorn water sampler was used to collect zooplankton. In January 2002, zooplankton showed a pronounced diel vertical migration whereby zooplankton were moving upward at around sunset and ...

  9. Zooplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Jyothibabu, R.; Madhu, N.V.

    , based on Gauns (2000), indicates the presence of a rich microzooplankton community in the Mandovi and Zuari estuaries. The community is qualitatively and quantitatively dominated by ciliated protozoans (e.g., tintinnids), with nearly 60 species recorded...; Oceanography and Marine Biology: An Annual Review 28 381?496. ?lvares Claude (2002) Fish, Curry and Rice (Revised 4th edn.). Goa Foundation. Alzieu C. (2000) Environmental impact of TBT: the French experience; Science of the Total Environment 258 99?102. Alzieu...

  10. Can small zooplankton mix lakes?

    OpenAIRE

    Simoncelli, S.; Thackeray, S.J.; Wain, D.J.

    2017-01-01

    The idea that living organisms may contribute to turbulence and mixing in lakes and oceans (biomixing) dates to the 1960s, but has attracted increasing attention in recent years. Recent modeling and experimental studies suggest that marine organisms can enhance turbulence as much as winds and tides in oceans, with an impact on mixing. However, other studies show opposite and contradictory results, precluding definitive conclusions regarding the potential importance of biomixing. For lakes, on...

  11. Increased zooplankton PAH concentrations across hydrographic fronts in the East China Sea.

    Science.gov (United States)

    Hung, Chin-Chang; Ko, Fung-Chi; Gong, Gwo-Ching; Chen, Kuo-Shu; Wu, Jian-Ming; Chiang, Hsin-Lun; Peng, Sen-Chueh; Santschi, Peter H

    2014-06-15

    The Changjiang has transported large quantities of polycyclic aromatic hydrocarbons (PAHs) to the East China Sea (ECS), but information of these pollutants in zooplankton is limited. To understand PAHs pollution in zooplankton in the ECS, total concentrations of PAHs in zooplankton from surface waters were measured. Values of PAHs ranged from 2 to 3500 ng m(-3) in the ECS, with highest PAHs levels located at the salinity front between the Changjiang Diluted Water (CDW) and the mid-shelf waters. In contrast, concentrations of zooplankton PAHs in the mid-shelf and outer-shelf waters were significantly lower (2-23 ng m(-3)) than those in the CDW. These results demonstrate that PAHs are conspicuously accumulated in zooplankton at the salinity front between the CDW and the mid-shelf waters. These higher levels of PAHs in zooplankton at the salinity front may be further biomagnified in marine organisms of higher trophic levels through their feeding activities. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Nutrient supply, surface currents, and plankton dynamics predict zooplankton hotspots in coastal upwelling systems

    Science.gov (United States)

    Messié, Monique; Chavez, Francisco P.

    2017-09-01

    A simple combination of wind-driven nutrient upwelling, surface currents, and plankton growth/grazing equations generates zooplankton patchiness and hotspots in coastal upwelling regions. Starting with an initial input of nitrate from coastal upwelling, growth and grazing equations evolve phytoplankton and zooplankton over time and space following surface currents. The model simulates the transition from coastal (large phytoplankton, e.g., diatoms) to offshore (picophytoplankton and microzooplankton) communities, and in between generates a large zooplankton maximum. The method was applied to four major upwelling systems (California, Peru, Northwest Africa, and Benguela) using latitudinal estimates of wind-driven nitrate supply and satellite-based surface currents. The resulting zooplankton simulations are patchy in nature; areas of high concentrations coincide with previously documented copepod and krill hotspots. The exercise highlights the importance of the upwelling process and surface currents in shaping plankton communities.

  13. Zooplankton trophic niches respond to different water types of the western Tasman Sea: A stable isotope analysis

    Science.gov (United States)

    Henschke, Natasha; Everett, Jason D.; Suthers, Iain M.; Smith, James A.; Hunt, Brian P. V.; Doblin, Martina A.; Taylor, Matthew D.

    2015-10-01

    The trophic relationships of 21 species from an oceanic zooplankton community were studied using stable isotopes of carbon and nitrogen. Zooplankton and suspended particulate organic matter (POM) were sampled in three different water types in the western Tasman Sea: inner shelf (IS), a cold core eddy (CCE) and a warm core eddy (WCE). δ15N values ranged from 3.9‰ for the parasitic copepod Sapphirina augusta to 10.2‰ for the euphausiid, Euphausia spinifera. δ13C varied from -22.6 to -19.4‰ as a result of the copepod Euchirella curticauda and E. spinifera. The isotopic composition of POM varied significantly among water types; as did the trophic enrichment of zooplankton over POM, with the lowest enrichment in the recently upwelled IS water type (0.5‰) compared to the warm core eddy (1.6‰) and cold core eddy (2.7‰). The WCE was an oligotrophic environment and was associated with an increased trophic level for omnivorous zooplankton (copepods and euphausiids) to a similar level as carnivorous zooplankton (chaetognaths). Therefore carnivory in zooplankton can increase in response to lower abundance and reduced diversity in their phytoplankton and protozoan prey. Trophic niche width comparisons across three zooplankton species: the salp Thalia democratica, the copepod Eucalanus elongatus and the euphausiid Thysanoessa gregaria, indicated that both niche partitioning and competition can occur within the zooplankton community. We have shown that trophic relationships among the zooplankton are dynamic and respond to different water types. The changes to the zooplankton isotopic niche, however, were still highly variable as result of oceanographic variation within water types.

  14. Ecological factors affecting the distribution of zooplankton ...

    African Journals Online (AJOL)

    USER

    and ecological functioning of aquatic ecosystems, which must be taken into account ... zooplankton, which is its key position in the trophic chain, gives a fundamental role ..... suspended solids can block the filtering apparatus and impede their ...

  15. Zooplankton along the Tamil Nadu coast

    Digital Repository Service at National Institute of Oceanography (India)

    Santhakumari, V.; Saraswathy, M.

    Zooplankton abundance along two sectors at Cape Comorin and Tuticorin of Tamil Nadu Coast, southeast coast of India was studied. High biomass contributed by Ostracods, Salps, Chaetognaths etc., were observed along Tuticorin transect. In the Cape...

  16. Diurnal variation of zooplankton off Versova (Bombay)

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Nair, V.R.; Desai, B.N.

    Physicochemical parameters and diurnal variaion of zooplankton were studied off Versova on 17/18 February 1981. Salinity and dissolved oxygen showed limited variation during the period of study. Nutrient values followed the tidal rhythm and high...

  17. The effects of juvenile American shad planktivory on zooplankton production in Columbia River food webs

    Science.gov (United States)

    Haskell, Craig A.; Tiffan, Kenneth F.; Rondorf, Dennis W.

    2013-01-01

    Columbia River reservoirs support a large population of nonnative American Shad Alosa sapidissima that consume the zooplankton that native fishes also rely on. We hypothesized that the unprecedented biomass of juvenile American Shad in John Day Reservoir is capable of altering the zooplankton community if these fish consume a large portion of the zooplankton production. We derived taxon-specific estimates of zooplankton production using field data and a production model from the literature. Empirical daily ration was estimated for American Shad and expanded to population-level consumption using abundance and biomass data from hydroacoustic surveys. Daphnia spp. production was high in early summer but declined to near zero by September as shad abundance increased. American Shad sequentially consumed Daphnia spp., copepods, and Bosmina spp., which tracked the production trends of these taxa. American Shad evacuation rates ranged from 0.09 to 0.24/h, and daily rations ranged from 0.008 to 0.045 g·g−1·d−1 (dry weight) over all years. We observed peak American Shad biomass (45.2 kg/ha) in 1994, and daily consumption (1.6 kg/ha) approached 30% (5.3 kg/ha) of zooplankton production. On average, American Shad consumed 23.6% of the available zooplankton production (range, food web in John Day Reservoir, potentially affecting native fishes, including Pacific salmon Oncorhynchus spp.

  18. 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

  19. Validity of zooplankton biomass estimates and energy equivalent in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.; Parulekar, A.H.

    , as deduced from the data on biochemical composition and energy content, it is evident that zooplankton of the Indian Ocean contains on an average 2.7% organic carbon, rather than the widely quoted value of 6.5%. The biomass production in terms of organic...

  20. 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 μm) 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

  1. Virtual Organizations: Trends and Models

    Science.gov (United States)

    Nami, Mohammad Reza; Malekpour, Abbaas

    The Use of ICT in business has changed views about traditional business. With VO, organizations with out physical, geographical, or structural constraint can collaborate with together in order to fulfill customer requests in a networked environment. This idea improves resource utilization, reduces development process and costs, and saves time. Virtual Organization (VO) is always a form of partnership and managing partners and handling partnerships are crucial. Virtual organizations are defined as a temporary collection of enterprises that cooperate and share resources, knowledge, and competencies to better respond to business opportunities. This paper presents an overview of virtual organizations and main issues in collaboration such as security and management. It also presents a number of different model approaches according to their purpose and applications.

  2. Species composition, abundance and distribution of zooplankton in a tropical eutrophic lake: Lake Catemaco, México

    OpenAIRE

    Roberto E. Torres-Orozco B.; Sandra A. Zanatta

    1998-01-01

    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 havanaens...

  3. Zooplankton and zoobenthos of the Mokra Sura river

    Directory of Open Access Journals (Sweden)

    V. Yakovenko

    2017-12-01

    Full Text Available Purpose. To study the spatial distribution of structural and functional indicators of zooplankton and zoobenthos during the period of maximum development of hydrobiocenosis in the contaminated and conditionally clean sites of the Mokra Sura river being under antropogenic pressure. Methodology. During the collection and subsequent laboratory processing of zooplankton and zoobenthos samples, we used the standard conventional hydrobiological methods. In order to rank the studied river sites, we used the combined index of the community state (CICS based on the structural-functional indicators of zoobenthos. Findings. The research results have shown that the species composition of zoobenthos and zooplankton of the Mokra Sura river included many saprobiontic species such as oligochaetes, chironomids and rotifers, which were developed significantly in some sites under the effect of eutrophication and silt accumulation in the presence of anthropogenic pollution. The above-mentioned processes cause inhibition of the life activity of such filter feeders as mollusks and crustaceans being the most powerful zooplanktonic and zoobenthic agents of self-cleaning. The highest numbers of zooplankton and zoobenthos development were recorded in front of the point of the emergency discharge of right-bank sewage water (stimulating effect of organic pollution while the lowest numbers were registered near the tire plant (combined effect of both chemical sewage pollution and silt accumulation. In the «Dnipro - Zaporizhzhia highway» site, low numbers of zooplankton development were the result of silt accumulation, whereas the zoobenthos biomass turned out to be the highest due to the intensive development of oligochaetes. Planktonic saprobiontic rotifers dominated in the site located in front of the sewage discharge whereas bdelloid rotifers dominated in the upstream sites of the river. The dominance of planktonic and benthic saprobiontic rotifers caused the highest

  4. Zooplankton variability in polluted and unpolluted waters off Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Desai, B.N.

    Zooplankton abundance in the waters around Bombay was studied at Versova, Bombay Harbour (less polluted), Mahim and Thana (highly polluted) from October 1977 to December 1978. A rich zooplankton population was observed throughout the period of study...

  5. Annual variations in zooplankton from a polluted coastal environment

    Digital Repository Service at National Institute of Oceanography (India)

    Haridas, P.; Menon, P.G.; Madhupratap, M.

    Seasonal changes in the composition and distribution of zooplankton from the coastal waters of Trivandrum were studied. The study indicated that the effluent discharged from a nearby titanium dioxide factory did not affect the zooplankton abundance...

  6. Model of organ dose combination

    International Nuclear Information System (INIS)

    Valley, J.-F.; Lerch, P.

    1977-01-01

    The ICRP recommendations are based on the limitation of the dose to each organ. In the application and for a unique source the critical organ concept allows to limit the calculation and represents the irradiation status of an individuum. When several sources of radiation are involved the derivation of the dose contribution of each source to each organ is necessary. In order to represent the irradiation status a new parameter is to be defined. Propositions have been made by some authors, in particular by Jacobi introducing at this level biological parameters like the incidence rate of detriment and its severity. The new concept is certainly richer than a simple dose notion. However, in the actual situation of knowledge about radiation effects an intermediate parameter, using only physical concepts and the maximum permissible doses to the organs, seems more appropriate. The model, which is a generalization of the critical organ concept and shall be extended in the future to take the biological effects into account, will be presented [fr

  7. Zooplankton biomass to chlorophyll ratios in relation to trophic status ...

    African Journals Online (AJOL)

    Rising eutrophication in South African reservoirs is of major concern, leading to the consideration of top-down biomanipulation as a management option – reducing zooplankton-eating fish to sustain zooplankton grazing pressure and thus restrict autotrophic plankton that proliferate with nutrient increases. The biomass ratio ...

  8. Composition and abundance of the zooplankton community in the ...

    African Journals Online (AJOL)

    The taxonomic composition of the zooplankton community of the Bitter Lakes, Egypt, was examined in 2003–2004 in relation to the spatial and temporal distribution of environmental factors. Copepoda were dominant, forming 49% of the zooplankton, followed by Protista at 37%. During the autumn, zooplankton in Small ...

  9. 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 δ13C and δ15N 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 δ15N ratios were influenced by zooplankton size class, presumably reflecting ontogenetic changes in diet. ANOVA post hoc results and correlations in δ15N signatures among treatments suggest that gut contents may not affect overall nitrogen signatures of Euphausia spp., but that δ13C 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

  10. Concentration and toxicity of some metals in zooplankton from nearshore waters of Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Nair, V.R.; Narvekar, P.V.; Desai, B.N.

    Zooplankton samples collected from 4 stations located in the nearshore waters of Bombay were analysed for Cu, Co, Mn, Ni and Cd. Concentrations of Co, Mn and Ni were more in copepods and gelatinous organisms than in mysids and decapods. High...

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

    International Nuclear Information System (INIS)

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

    1979-01-01

    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

  12. Estimation of biological parameters of marine organisms using linear and nonlinear acoustic scattering model-based inversion methods.

    Science.gov (United States)

    Chu, Dezhang; Lawson, Gareth L; Wiebe, Peter H

    2016-05-01

    The linear inversion commonly used in fisheries and zooplankton acoustics assumes a constant inversion kernel and ignores the uncertainties associated with the shape and behavior of the scattering targets, as well as other relevant animal parameters. Here, errors of the linear inversion due to uncertainty associated with the inversion kernel are quantified. A scattering model-based nonlinear inversion method is presented that takes into account the nonlinearity of the inverse problem and is able to estimate simultaneously animal abundance and the parameters associated with the scattering model inherent to the kernel. It uses sophisticated scattering models to estimate first, the abundance, and second, the relevant shape and behavioral parameters of the target organisms. Numerical simulations demonstrate that the abundance, size, and behavior (tilt angle) parameters of marine animals (fish or zooplankton) can be accurately inferred from the inversion by using multi-frequency acoustic data. The influence of the singularity and uncertainty in the inversion kernel on the inversion results can be mitigated by examining the singular values for linear inverse problems and employing a non-linear inversion involving a scattering model-based kernel.

  13. 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 μmol 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.

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

    Science.gov (United States)

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

    2008-08-01

    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 and 10.13 μmol 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.

  15. Future marine zooplankton research - a perspective

    DEFF Research Database (Denmark)

    Bathmann, U.; Bundy, M.H.; Clarke, M.E.

    2001-01-01

    and existence of dominant zooplankton taxa, and (2) the control of biodiversity and biocomplexity, for example, in the tropical ocean where diversity is high. These recommendations come from an assemblage of chemical, physical and biological oceanographers with experience in major interdisciplinary studies...

  16. Mercury concentration variability in the zooplankton of the southern Baltic coastal zone

    Science.gov (United States)

    Bełdowska, Magdalena; Mudrak-Cegiołka, Stella

    2017-12-01

    Being a toxic element, mercury is introduced to the human organism through the consumption of fish and seafood, which in turn often feed on zooplankton. The bioaccumulation of Hg by zooplankton is an important factor influencing the magnitude of the mercury load introduced with food into the predator organism. Therefore the present article attempts to identify the processes and factors influencing Hg concentration in the zooplankton of the coastal zone, an area where marine organisms - an attractive food source for humans - thrive. This is particularly important in areas where climate changes influence the species composition and quantity of plankton. The studies were carried out on three test sites in the coastal zone of the southern Baltic Sea in the period from December 2011 to May 2013. The obtained results show that the shorting of the winter season is conducive to Hg increase in zooplankton and, consequently, in the trophic chain. High mercury concentrations were measured in genus Synchaeta and Keratella when Mesodinium rubrum were predominant in phytoplankton, while other sources of this metal in the plankton fauna were epilithon, epiphton and microbenthos. This is of particular importance when it comes to sheltered bays and estuaries with low water dynamics.

  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

  18. Nutrients, phytoplankton, zooplankton, and macrobenthos

    Science.gov (United States)

    Rudstam, Lars G.; Holeck, Kristen T.; Watkins, James M.; Hotaling, Christopher; Lantry, Jana R.; Bowen, Kelly L.; Munawar, Mohi; Weidel, Brian C.; Barbiero, Richard; Luckey, Frederick J.; Dove, Alice; Johnson, Timothy B.; Biesinger, Zy

    2017-01-01

    Lower trophic levels support the prey fish on which most sport fish depend. Therefore, understanding the production potential of lower trophic levels is integral to the management of Lake Ontario’s fishery resources. Lower trophic-level productivity differs among offshore and nearshore waters. In the offshore, there is concern about the ability of the lake to support Alewife (Table 1) production due to a perceived decline in productivity of phytoplankton and zooplankton whereas, in the nearshore, there is a concern about excessive attached algal production (e.g., Cladophora) associated with higher nutrient concentrations—the oligotrophication of the offshore and the eutrophication of the nearshore (Mills et al. 2003; Holeck et al. 2008; Dove 2009; Koops et al. 2015; Stewart et al. 2016). Even though the collapse of the Alewife population in Lake Huron in 2003 (and the associated decline in the Chinook Salmon fishery) may have been precipitated by a cold winter (Dunlop and Riley 2013), Alewife had not returned to high abundances in Lake Huron as of 2014 (Roseman et al. 2015). Failure of the Alewife population to recover from collapse has been attributed to declines in lower trophic-level production (Barbiero et al. 2011; Bunnell et al. 2014; but see He et al. 2015). In Lake Michigan, concerns of a similar Alewife collapse led to a decrease in the number of Chinook Salmon stocked. If lower trophic-level production declines in Lake Ontario, a similar management action could be considered. On the other hand, in Lake Erie, which supplies most of the water in Lake Ontario, eutrophication is increasing and so are harmful algal blooms. Thus, there is also a concern that nutrient levels and algal blooms could increase in Lake Ontario, especially in the nearshore. Solutions to the two processes of concern—eutrophication in the nearshore and oligotrophication in the offshore—may be mutually exclusive. In either circumstance, fisheries management needs information on

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

    International Nuclear Information System (INIS)

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

    1980-01-01

    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 239 240 Pu, 238 U, 232 Th, and 210 Po 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

  20. 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.

  1. Effects of the ``Amoco Cadiz'' oil spill on zooplankton

    Science.gov (United States)

    Samain, J. F.; Moal, J.; Coum, A.; Le Coz, J. R.; Daniel, J. Y.

    1980-03-01

    A survey of zooplankton physiology on the northern coast of Brittany (France) was carried out over a one-year period by comparing two estuarine areas, one oil-polluted area (Aber Benoit) following the oil spill by the tanker “Amoco Cadiz” and one non-oil-polluted area (Rade de Brest). A new approach to an ecological survey was made by describing trophic relationships using analysis of digestive enzyme equipment (amylase and trypsin) of zooplankton organisms, mesoplankton populations and some selected species. These measurements allowed determination of (a) groups of populations with homogeneous trophic and faunistic characteristics and (b) groups of species with homogeneous trophic characteristics. The study of the appearance of these groups over a one-year period revealed the succession of populations and their adaptation to the environment on the basis of biochemical analysis. These phenomena observed in the compared areas showed marked differences in the most polluted areas during the productive spring period. Specific treatment of the data using unusual correlations between digestive enzymes is discussed in terms of the immediate effect on the whole population and on a copepod ( Anomalocera patersoni) living in the upper 10 cm.

  2. 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

  3. Patchy zooplankton grazing and high energy conversion efficiency: ecological implications of sandeel behavior and strategy

    DEFF Research Database (Denmark)

    Deurs, Mikael van; Christensen, Asbjørn; Rindorf, Anna

    2013-01-01

    of prey. Here we studied zooplankton consumption and energy conversion efficiency of lesser sandeel (Ammodytes marinus) in the central North Sea, using stomach data, length and weight-at-age data, bioenergetics, and hydrodynamic modeling. The results suggested: (i) Lesser sandeel in the Dogger area depend...... sandeel densities and growth rates per area than larger habitats...

  4. Power-plant-related estuarine zooplankton studies

    International Nuclear Information System (INIS)

    Sage, L.E.; Olson, M.M.

    1981-01-01

    In-plant studies examining the effects of entrainment on zooplankton and field studies examining zooplankton abundance, composition, and distribution in the Chesapeake Bay in the vicinity of Calvert Cliffs Nuclear Power Plant have been conducted from 1974 to the present. The evolution of these studies, with particular emphasis on design and statistical treatment, is discussed. Entrainment study designs evolved from discrete sampling episodes at 4-h intervals over 24 h to a time-series sampling design in which sampling took place every 30 min over 24 and 48-h periods. The near-field study design and samping methods have included replicated net tows, using 0.5-m nets, and replicated and nonreplicated pumped sampling, using a high-speed centrifugal pump. 16 refs

  5. 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

  6. Zooplankton composition and diversity at different location along Kalpakkam coastal sites

    International Nuclear Information System (INIS)

    Das, Subhashree; Ponnusamy, K.; Verma, Amrata; Munilkumar, S.; Rajaram, S.; Lakra, W.S.; Pal, Asim K.; Sreedevi, K.R.

    2015-01-01

    Zooplanktons are the base of aquatic food web which constitutes the most vital biological component in an aquatic ecosystem. They form an important link in the food chain from primary to tertiary level leading to the production of fishery and are known to serve as a food for larger organisms such as bivalves, crustaceans and fish. The present study was aimed to assess the composition and diversity among the different species of zooplankton in Kalpakkam coastal sites within 30 kms around Madras Atomic Power Station. Samples were collected using plankton net (mesh size 63 μm, mouth area 20 inch dia) from stations which were fixed using the GPS coordinates. The results of the present studies showed maximum zoo planktonic diversity in station N15 i.e. 15 km away from MAPS (Madras Atomic Power Station), as compared to the other selected sampling stations. Regarding composition of zooplankton at different sites along the MAPS, it was found Copepods dominated among the zooplankton forming up to 60% of total species composition which indicate that copepod species are likely to be good indicators of water-mass influence and changes. (author)

  7. Potential acidification impacts on zooplankton in CCS leakage scenarios.

    Science.gov (United States)

    Halsband, Claudia; Kurihara, Haruko

    2013-08-30

    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. The temporal dynamics of zooplankton communities of different types of water bodies within Ichniansky National Park

    Directory of Open Access Journals (Sweden)

    Z. V. Burian

    2017-05-01

    Full Text Available In recent decades, the influence of anthropogenic impact on aquatic ecosystems has increased. This has led to a restructuring of aquatic ecosystems and affected the structural and functional organization of groups of aquatic organisms, causing qualitative and quantitative changes. Particular attention is drawn to the different types of water bodies of protected areas like IchnyanskyNational Park, which is located in Ichnyansky district of Chernihiv region. This park is a newly created one, so the reduction in intensity of anthropogenic pressure can be traced within its waters. Zooplankton plays an important role in the functioning of trophic networks because it transfers energy from producers and primary consumers to young fish and planktonophagous fish. Therefore, three main groups of zooplankton were chosen as the object of study: rotifers (class Eurotatoria, cladocerans (class Branchiopoda, order Cladocera, different age stages of copepods (class Copepoda, and also ostracods (Class Ostracoda. The zooplankton used as research material was collected in the daytime in spring (April, summer (late July – early August and autumn (late September – early October in the years 2015–2016 from ten experimental stations. During this period 81 species of zooplankton were recorded within heterogeneous reservoirs of IchnianskyNational Park. Monogonont rotifers (subclass Monogononta included 35 species (43% of all species and bdelloid rotifers (subclass Bdelloidea, cladocerns, comprised 28 species (35%, and copepods included 18 species (22%. The faunal range of zooplankton over different years and seasons was characterized by the predominance of the rotator complex in spring, rotator-cladocerans and cladocerans in summer, and of the cladocerans complex in autumn. This was due to the formation during spring and summer of favourable conditions in the waters for filter feeders, which consist generally of rotifers and cladocerans. In autumn the water

  9. using stereochemistry models in teaching organic compounds

    African Journals Online (AJOL)

    Preferred Customer

    The purpose of the study was to find out the effect of stereochemistry models on students' ... consistent with the names given to organic compounds. Some of ... Considering class level, what is the performance of the students in naming organic.

  10. Mercury kinetics in marine zooplankton

    International Nuclear Information System (INIS)

    Fowler, S.W.; Heyraud, M.; LaRosa, J.

    1976-01-01

    Mercury, like many other heavy metals, is potentially available to marine animals by uptake directly from water and/or through the organisms food. Furthermore, bioavailability, assimilation and subsequent retention in biota may be affected by the chemical species of the element in sea water. While mercury is known to exist in the inorganic form in sea water, recent work has indicated that, in certain coastal areas, a good portion of the total mercury appears to be organically bound; however, the exact chemical nature of the organic fraction has yet to be determined. Methyl mercury may be one constituent of the natural organically bound fraction since microbial mechanisms for in situ methylation of mercury have been demonstrated in the aquatic environment. Despite the fact that naturally produced methyl mercury probably comprises only a small fraction of an aquatic ecosystem, the well-documented toxic effects of this organo-mercurial, caused by man-made introductions into marine food chains, make it an important compound to study

  11. Studies on zooplankton from the Arabian sea off the south-central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sumitra-Vijayaraghavan; Selvakumar, R.A.; Rao, T.S.S.

    Zooplankton biomass, composition and biochemical constituents were studied. Estimated average zooplankton biomass was 8.76 ml/100 m super(3). Of the major components constituting the zooplankton biomass, copepods formed the dominant group. Protein...

  12. Zooplankton use of chemodetection to find and eat particles

    DEFF Research Database (Denmark)

    Jackson, G.A.; Kiørboe, Thomas

    2004-01-01

    The ability of raptorial zooplankton to find large particles such as marine aggregates is crucial to their use of the particles as food and to the fate of the particles. Kiorboe & Thygesen (2001) developed a numerical approach to describe particle detection by chemosensory zooplankton. In this pa......The ability of raptorial zooplankton to find large particles such as marine aggregates is crucial to their use of the particles as food and to the fate of the particles. Kiorboe & Thygesen (2001) developed a numerical approach to describe particle detection by chemosensory zooplankton...

  13. Reconstruction of long-term changes in lake water chemistry, zooplankton and benthos of a small, acidified high-mountain lake: magic modelling and palaeolimnogical analysis

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, E.; Appleby, P.; Bitušík, P.; Curtis, C.; Fott, J.; Kopáček, Jiří; Pražáková, M.; Rose, N.; Strunecký, O.; Wright, R. F.

    2002-01-01

    Roč. 2, č. 2 (2002), s. 127-138 ISSN 1567-7230 Grant - others:EC(XE) MOLAR ENV4-CT95-007; EC(XE) EMERGE EVK1-CT1999-00032 Keywords : modeling * palaeolimnology * hydrochemistry Subject RIV: DA - Hydrology ; Limnology

  14. Elemental concentration of zooplankton and their particulate products

    International Nuclear Information System (INIS)

    Fowler, S.W.; Oregioni, B.

    1974-01-01

    Since zooplankton fecal pellets and molts are major vectors in the vertical transport of zinc in the sea, analyses have been made also for other trace metals in these particulate products. Euphausiids and pelagic shrimp were collected live off the Monaco coast by taking several short oblique tows with an Issacs-Kidd midwater trawl. Animals were placed in clean sea water, sorted according to species and immediately transported to the laboratory in plastic containers filled with filtered sea water taken at the collection site. Samples of microplankton, which serve as food for the macroplankton were also taken. Elemental concentrations in whole euphausiids and shrimp were measured. It was observed that molt analyses strongly support the contention that crustacean molts play an important role in the transport of metals and radionuclides in marine ecosystems. Molts can release metals to the water column or sediments upon decomposition or serve as a rich source of metals for organisms of other trophic levels which ingest them

  15. Vertical nitrogen flux from the oceanic photic zone by diel migrant zooplankton and nekton

    Science.gov (United States)

    Longhurst, Alan R.; Glen Harrison, W.

    1988-06-01

    Where the photic zone is a biological steady-state, the downward flux of organic material across the pycnocline to the interior of the ocean is thought to be balanced by upward turbulent flux of inorganic nitrogen across the nutricline. This model ignores a significant downward dissolved nitrogen flux caused by the diel vertical migration of interzonal zooplankton and nekton that feed in the photic zone at night and excrete nitrogenous compounds at depth by day. In the oligotrophic ocean this flux can be equivalent to the flux of particulate organic nitrogen from the photic zone in the form of faecal pellets and organic flocculates. Where nitrogen is the limiting plant nutrient, and the flux by diel migration of interzonal plankton is significant compared to other nitrogen exports from the photic zone, there must be an upward revision of previous estimates for the ratio of new to total primary production in the photic zone if a nutrient balance is to be maintained. This upward revision is of the order 5-100% depending on the oceanographic regime.

  16. Tree-Structured Digital Organisms Model

    Science.gov (United States)

    Suzuki, Teruhiko; Nobesawa, Shiho; Tahara, Ikuo

    Tierra and Avida are well-known models of digital organisms. They describe a life process as a sequence of computation codes. A linear sequence model may not be the only way to describe a digital organism, though it is very simple for a computer-based model. Thus we propose a new digital organism model based on a tree structure, which is rather similar to the generic programming. With our model, a life process is a combination of various functions, as if life in the real world is. This implies that our model can easily describe the hierarchical structure of life, and it can simulate evolutionary computation through mutual interaction of functions. We verified our model by simulations that our model can be regarded as a digital organism model according to its definitions. Our model even succeeded in creating species such as viruses and parasites.

  17. Modelling organic particles in the atmosphere

    International Nuclear Information System (INIS)

    Couvidat, Florian

    2012-01-01

    Organic aerosol formation in the atmosphere is investigated via the development of a new model named H 2 O (Hydrophilic/Hydrophobic Organics). First, a parameterization is developed to take into account secondary organic aerosol formation from isoprene oxidation. It takes into account the effect of nitrogen oxides on organic aerosol formation and the hydrophilic properties of the aerosols. This parameterization is then implemented in H 2 O along with some other developments and the results of the model are compared to organic carbon measurements over Europe. Model performance is greatly improved by taking into account emissions of primary semi-volatile compounds, which can form secondary organic aerosols after oxidation or can condense when temperature decreases. If those emissions are not taken into account, a significant underestimation of organic aerosol concentrations occurs in winter. The formation of organic aerosols over an urban area was also studied by simulating organic aerosols concentration over the Paris area during the summer campaign of Megapoli (July 2009). H 2 O gives satisfactory results over the Paris area, although a peak of organic aerosol concentrations from traffic, which does not appear in the measurements, appears in the model simulation during rush hours. It could be due to an underestimation of the volatility of organic aerosols. It is also possible that primary and secondary organic compounds do not mix well together and that primary semi volatile compounds do not condense on an organic aerosol that is mostly secondary and highly oxidized. Finally, the impact of aqueous-phase chemistry was studied. The mechanism for the formation of secondary organic aerosol includes in-cloud oxidation of glyoxal, methylglyoxal, methacrolein and methylvinylketone, formation of methyltetrols in the aqueous phase of particles and cloud droplets, and the in-cloud aging of organic aerosols. The impact of wet deposition is also studied to better estimate the

  18. Acoustic discrimination of Southern Ocean zooplankton

    Science.gov (United States)

    Brierley, Andrew S.; Ward, Peter; Watkins, Jonathan L.; Goss, Catherine

    Acoustic surveys in the vicinity of the sub-Antarctic island of South Georgia during a period of exceptionally calm weather revealed the existence of a number of horizontally extensive yet vertically discrete scattering layers in the upper 250 m of the water column. These layers were fished with a Longhurst-Hardy plankton recorder (LHPR) and a multiple-opening 8 m 2 rectangular mid-water trawl (RMT8). Analysis of catches suggested that each scattering layer was composed predominantly of a single species (biovolume>95%) of either the euphausiids Euphausia frigida or Thysanöessa macrura, the hyperiid amphipod Themisto gaudichaudii, or the eucalaniid copepod Rhincalanus gigas. Instrumentation on the nets allowed their trajectories to be reconstructed precisely, and thus catch data to be related directly to the corresponding acoustic signals. Discriminant function analysis of differences between mean volume backscattering strength at 38, 120 and 200 kHz separated echoes originating from each of the dominant scattering layers, and other signals identified as originating from Antarctic krill ( Euphausia superba), with an overall correct classification rate of 77%. Using echo intensity data alone, gathered using hardware commonly employed for fishery acoustics, it is therefore possible to discriminate in situ between several zooplanktonic taxa, taxa which in some instances exhibit similar gross morphological characteristics and have overlapping length- frequency distributions. Acoustic signals from the mysid Antarctomysis maxima could also be discriminated once information on target distribution was considered, highlighting the value of incorporating multiple descriptors of echo characteristics into signal identification procedures. The ability to discriminate acoustically between zooplankton taxa could be applied to provide improved acoustic estimates of species abundance, and to enhance field studies of zooplankton ecology, distribution and species interactions.

  19. Zooplankton as a compound mineralising and synthesizing system: Phosphorus excretion

    NARCIS (Netherlands)

    Gulati, R.D.; Martinez, C.P.; Siewertsen, K.

    1995-01-01

    Data on phosphate excretion rates of zooplankton are based on measurements using the pelagic crustacean zoo-plankton of Lake Vechten and laboratory-cultured Daphnia galeata. In case of Daphnia sp we measured the effects of feeding on P-rich algae and P-poor algae (Scenedesmus) as food on the

  20. Some crustacean zooplankton of Wular lake in Kashmir Himalaya ...

    African Journals Online (AJOL)

    In a taxonomic survey of crustacean zooplankton collected from Wular lake of Kashmir, a pictorial key was developed. Thirty-six (36) pictures of 25 species of crustacean zooplankton, out of which 21 represented 16 Cladocera taxa belonging to Chydoridae (Alona affinis, A. rectangula and A. monacantha, Chydorus ...

  1. Selective uptake of 55Fe from seawater by zooplankton

    International Nuclear Information System (INIS)

    Jennings, C.D.

    1978-01-01

    Iron-55 was measured in water and mixed zooplankton collected in the South Pacific Ocean. The ratios of the specific activity of 55 Fe (pCi/g Fe) between plankton and water from the same locations appear to be about 100, which suggests that zooplankton took up 55 Fe in preference to stable iron in the South Pacific Ocean

  2. Effects of UV-B irradiated algae on zooplankton grazing

    NARCIS (Netherlands)

    Lange, de H.J.; Lürling, M.F.L.L.W.

    2003-01-01

    We tested the effects of UV-B stressed algae on grazing rates of zooplankton. Four algal species ( Chlamydomonas reinhardtii, Cryptomonas sp., Scenedesmus obliquus and Microcystis aeruginosa) were used as food and fed to three zooplankton species ( Daphnia galeata, Bosmina longirostris and

  3. Zooplankton composition and community structure in Lake Tiga ...

    African Journals Online (AJOL)

    Zooplankton in Lake Tiga was identified and its community structure assessed between March 2009 and March 2011. A total of 54 species of zooplankton was recorded, comprising two species of Protozoa, 26 species of Rotifera, eight species of Copepoda, 11 species of Cladocera, four species of Ostracoda and three ...

  4. Monsoon regime in the Indian Ocean and zooplankton variability

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.

    and the estuaries in order to show how the monsoon exerts its influence on zooplankton from different types of environment. In the open ocean, the semi-annually reversing system of currents exert profound influence on the shifting of zooplankton populations and its...

  5. 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

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

    International Nuclear Information System (INIS)

    Almquist, Elisabeth

    1970-11-01

    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

  7. How do copper contamination pulses shape the regime shifts of phytoplankton-zooplankton dynamics?

    Science.gov (United States)

    Camara, B. I.; Yamapi, R.; Mokrani, H.

    2017-07-01

    The presence of pollutants in waters, particularly from heavy metals, is of grave concern worldwide due to its cytotoxicity to organisms. Fish and aquatic organisms are very sensitive to the increasing Cu concentrations in water. Therefore, Cu toxicity partly depends on water quality. To address the effects of impulsive copper contamination of the phytoplankton-zooplankton population dynamics, we've built a model that focuses on the interaction between algae and Daphnia with deterministic and stochastic impulse copper. In fact the Results have shown three types of outcomes depending on copper concentration. In low (4.4 μgL-1) copper concentration, deterministic and stochastic pulses may promote the persistence of Daphnia and algae populations unlike the absence of pulses. Whereas, in high (28 μgL-1) concentration, it accelerates deficiency and toxicity processes, leads to the extinction of all populations and in intermediate concentrations. Deterministic and stochastic pulses may transform population dynamics in complex oscillations. Numerical results show that the system that has been considered has more complex dynamics including bifurcation, period-doubling oscillations and chaos. Depending on minimum copper concentration in the environment, the bifurcation diagram has highlighted the resilience or the regime shifts of the system in occurrence of pulse contamination.

  8. Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton.

    Directory of Open Access Journals (Sweden)

    Delphine Nicolas

    Full Text Available The North Sea cod (Gadus morhua, L. stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature and/or indirect (i.e. changes in the quantity and quality of zooplankton prey effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability.

  9. 210Po/210Pb dynamics in relation to zooplankton biomass and trophic conditions during an annual cycle in northwestern Mediterranean coastal waters

    International Nuclear Information System (INIS)

    Färber Lorda, Jaime; Fowler, Scott W.; Miquel, Juan-Carlos; Rodriguez y Baena, Alessia; Jeffree, Ross A.

    2013-01-01

    Monthly sampling in northwestern Mediterranean coastal waters was undertaken to better understand the relationship between zooplankton biomass and the cycling of the natural radionuclide 210 Po/ 210 Pb pair during a one-year period (October 1995–November 1996). In conjunction with mesozooplankton collections and 210 Po/ 210 Pb measurements in seawater, zooplankton and their fecal pellets, the biochemical composition of particulate organic matter (POM) was also examined at three depths (0, 20 and 50 m) as an indicator of trophic conditions. During May 1996, a strong zooplankton “bloom” was observed which was preceded by a prolonged increase in POM (protein + carbohydrates + lipids) starting at the end of March, and further demonstrated by a concomitant increase in the concentration of smaller particles, two features that are typical of mesotrophic waters. Simultaneous measurements of 210 Po in sea water and zooplankton showed an inverse trend between these two parameters during the sampling period, with the two lowest 210 Po concentrations in the dissolved phase of seawater coincident with the highest radionuclide concentrations in the zooplankton; however, this apparent relationship was not statistically significant over the entire year. Freshly excreted mesozooplankton and salp fecal pellets, which have been strongly implicated in the removal and downward transport of these radionuclides from the upper water column, contained 210 Po and 210 Pb levels ranging from 175 to 878 and 7.5–486 Bq kg −1 dry weight, respectively. Salp pellets contained 5 and 10 times more 210 Po and 210 Pb than in fecal pellets produced by mixed zooplankton, a finding most likely related to their different feeding strategies. During the zooplankton biomass peak observed in May, the 210 Po concentration in zooplankton was at a minimum; however, in contrast to what has been reported to occur in some open sea oligotrophic waters, over the year no statistically significant inverse

  10. Organic production in a dynamic CGE model

    DEFF Research Database (Denmark)

    Jacobsen, Lars Bo

    2004-01-01

    for conventional production into land for organic production, a period of two years must pass before the land being transformed can be used for organic production. During that time, the land is counted as land of the organic industry, but it can only produce the conventional product. To handle this rule, we make......Concerns about the impact of modern agriculture on the environment have in recent years led to an interest in supporting the development of organic farming. In addition to environmental benefits, the aim is to encourage the provision of other “multifunctional” properties of organic farming...... such as rural amenities and rural development that are spillover benefit additional to the supply of food. In this paper we further develop an existing dynamic general equilibrium model of the Danish economy to specifically incorporate organic farming. In the model and input-output data each primary...

  11. Estimation of mortality for stage-structured zooplankton populations: What is to be done?

    Science.gov (United States)

    Ohman, Mark D.

    2012-05-01

    Estimation of zooplankton mortality rates in field populations is a challenging task that some contend is inherently intractable. This paper examines several of the objections that are commonly raised to efforts to estimate mortality. We find that there are circumstances in the field where it is possible to sequentially sample the same population and to resolve biologically caused mortality, albeit with error. Precision can be improved with sampling directed by knowledge of the physical structure of the water column, combined with adequate sample replication. Intercalibration of sampling methods can make it possible to sample across the life history in a quantitative manner. Rates of development can be constrained by laboratory-based estimates of stage durations from temperature- and food-dependent functions, mesocosm studies of molting rates, or approximation of development rates from growth rates, combined with the vertical distributions of organisms in relation to food and temperature gradients. Careful design of field studies guided by the assumptions of specific estimation models can lead to satisfactory mortality estimates, but model uncertainty also needs to be quantified. We highlight additional issues requiring attention to further advance the field, including the need for linked cooperative studies of the rates and causes of mortality of co-occurring holozooplankton and ichthyoplankton.

  12. Cardiac Electromechanical Models: From Cell to Organ

    Directory of Open Access Journals (Sweden)

    Natalia A Trayanova

    2011-08-01

    Full Text Available The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computation physiology and medicine. This review focuses on electromechanical (EM models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single cell models and the second half addresses organ models. At the subcelluar level, myofilament models represent actin-myosin interaction and Ca-based activation. Myofilament models and their refinements represent an overview of the development in the field. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered the cellular basis of the Frank-Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction-diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and

  13. Project-matrix models of marketing organization

    Directory of Open Access Journals (Sweden)

    Gutić Dragutin

    2009-01-01

    Full Text Available Unlike theory and practice of corporation organization, in marketing organization numerous forms and contents at its disposal are not reached until this day. It can be well estimated that marketing organization today in most of our companies and in almost all its parts, noticeably gets behind corporation organization. Marketing managers have always been occupied by basic, narrow marketing activities as: sales growth, market analysis, market growth and market share, marketing research, introduction of new products, modification of products, promotion, distribution etc. They rarely found it necessary to focus a bit more to different aspects of marketing management, for example: marketing planning and marketing control, marketing organization and leading. This paper deals with aspects of project - matrix marketing organization management. Two-dimensional and more-dimensional models are presented. Among two-dimensional, these models are analyzed: Market management/products management model; Products management/management of product lifecycle phases on market model; Customers management/marketing functions management model; Demand management/marketing functions management model; Market positions management/marketing functions management model. .

  14. The Zebrafish Model Organism Database (ZFIN)

    Data.gov (United States)

    U.S. Department of Health & Human Services — ZFIN serves as the zebrafish model organism database. It aims to: a) be the community database resource for the laboratory use of zebrafish, b) develop and support...

  15. 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 μg 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 μg 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.

  16. Complex Systems and Self-organization Modelling

    CERN Document Server

    Bertelle, Cyrille; Kadri-Dahmani, Hakima

    2009-01-01

    The concern of this book is the use of emergent computing and self-organization modelling within various applications of complex systems. The authors focus their attention both on the innovative concepts and implementations in order to model self-organizations, but also on the relevant applicative domains in which they can be used efficiently. This book is the outcome of a workshop meeting within ESM 2006 (Eurosis), held in Toulouse, France in October 2006.

  17. Seasonal and inter-annual variations in methyl mercury concentrations in zooplankton from boreal lakes impacted by deforestation or natural forest fires.

    Science.gov (United States)

    Garcia, Edenise; Carignan, Richard; Lean, David R S

    2007-08-01

    We compared the effects of natural and anthropogenic watershed disturbances on methyl mercury (MeHg) concentration in bulk zooplankton from boreal Shield lakes. MeHg in zooplankton was monitored for three years in nine lakes impacted by deforestation, in nine lakes impacted by wildfire, and in twenty lakes with undisturbed catchments. Lakes were sampled during spring, mid- and late summer. MeHg in zooplankton showed a seasonal trend: concentrations were the lowest in spring, then peaked in mid-summer and decreased in late summer. Over the three study years, MeHg concentrations observed in mid-summer in zooplankton from forest harvested lakes were significantly higher than in reference and fire-impacted lakes, whereas differences between these two groups of lakes were not significant. The pattern of distribution of MeHg in zooplankton during the different seasons paralleled that of dissolved organic carbon (DOC), which is known as a vector of Hg from watershed soils to lake water. Besides DOC, MeHg in zooplankton also showed a positive significant correlation with epilimnetic temperature and sulfate concentrations. An inter-annual decreasing trend in MeHg was observed in zooplankton from reference and fire-impacted lakes. In forest harvested lakes, however, MeHg concentrations remained higher and nearly constant over three years following the impact. Overall these results indicate that the MeHg pulse observed in zooplankton following deforestation by harvesting is relatively long-lived, and may have repercussions to the accumulation of MeHg along the food chain. Therefore, potential effects of deforestation on the Hg contamination of fish should be taken into account in forest management practices.

  18. Influence of the late winter bloom on migrant zooplankton metabolism and its implications on export fluxes

    Science.gov (United States)

    Putzeys, S.; Yebra, L.; Almeida, C.; Bécognée, P.; Hernández-León, S.

    2011-12-01

    Studies on carbon active fluxes due to diel migrants are scarce and critical for carbon flux models and biogeochemical estimates. We studied the temporal variability and vertical distribution of biomass, indices of feeding and respiration of the zooplanktonic community north off the Canary Islands during the end of the late winter bloom, in order to assess vertical carbon fluxes in this area. Biomass distribution during the day presented two dense layers of organisms at 0-200 m and around 500 m, whereas at night, most of the biomass concentrated in the epipelagic layer. The gut pigment flux (0.05-0.18 mgC·m - 2 ·d - 1 ) represented 0.22% of the estimated passive export flux (POC flux) while potential ingestion represented 3.91% of the POC (1.24-3.40 mgC·m - 2 ·d - 1 ). The active respiratory flux (0.50-1.36 mgC·m - 2 ·d - 1 ) was only 1.57% of the POC flux. The total carbon flux mediated by diel migrants (respiration plus potential ingestion) ranged between 3.37 and 9.22% of the POC flux; which is three-fold higher than calculating ingestion fluxes from gut pigments. Our results suggest that the fluxes by diel migrants play a small role in the downward flux of carbon in the open ocean during the post-bloom period.

  19. Zooplankton data collected by ELTANIN in Southern Oceans from zooplankton net casts; 13 October 1963 to 06 June 1968 (NODC Accession 9500111)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts from ELTANIN in the Southern Oceans. Data were collected from 13 October 1963 to 06 June 1968 by National...

  20. Zooplankton species identities collected from zooplankton net casts in Indian Ocean from 17 February 1960 to 23 July 1962 (NODC Accession 9400059)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities and other data were collected using zooplankton net casts in the Indian Ocean. Data were collected from 17 February 1960 to 23 July...

  1. Modeling self-organization of novel organic materials

    Science.gov (United States)

    Sayar, Mehmet

    In this thesis, the structural organization of oligomeric multi-block molecules is analyzed by computational analysis of coarse-grained models. These molecules form nanostructures with different dimensionalities, and the nanostructured nature of these materials leads to novel structural properties at different length scales. Previously, a number of oligomeric triblock rodcoil molecules have been shown to self-organize into mushroom shaped noncentrosymmetric nanostructures. Interestingly, thin films of these molecules contain polar domains and a finite macroscopic polarization. However, the fully polarized state is not the equilibrium state. In the first chapter, by solving a model with dipolar and Ising-like short range interactions, we show that polar domains are stable in films composed of aggregates as opposed to isolated molecules. Unlike classical molecular systems, these nanoaggregates have large intralayer spacings (a ≈ 6 nm), leading to a reduction in the repulsive dipolar interactions that oppose polar order within layers. This enables the formation of a striped pattern with polar domains of alternating directions. The energies of the possible structures at zero temperature are computed exactly and results of Monte Carlo simulations are provided at non-zero temperatures. In the second chapter, the macroscopic polarization of such nanostructured films is analyzed in the presence of a short range surface interaction. The surface interaction leads to a periodic domain structure where the balance between the up and down domains is broken, and therefore films of finite thickness have a net macroscopic polarization. The polarization per unit volume is a function of film thickness and strength of the surface interaction. Finally, in chapter three, self-organization of organic molecules into a network of one dimensional objects is analyzed. Multi-block organic dendron rodcoil molecules were found to self-organize into supramolecular nanoribbons (threads) and

  2. Seasonal variation of zooplankton abundance and community structure in Prince William Sound, Alaska, 2009-2016

    Science.gov (United States)

    McKinstry, Caitlin A. E.; Campbell, Robert W.

    2018-01-01

    Large calanoid copepods and other zooplankters comprise the prey field for ecologically and economically important predators such as juvenile pink salmon, herring, and seabirds in Prince William Sound (PWS).​ From 2009-2016, the Gulf Watch Alaska program collected zooplankton 5-10 times each year at 12 stations in PWS to establish annual patterns. Surveys collected 188 species of zooplankton with Oithona similis, Limacina helicina, Pseudocalanus spp., and Acartia longiremis as the most common species present in 519 samples. Generalized additive models assessed seasonal abundance and showed peak abundance in July (mean: 9826 no. m-3 [95% CI: 7990-12,084]) and lowest abundance in January (503 no. m-3 [373 to 678]). Significantly higher zooplankton abundance occurred in 2010 (542 no. m-3 ± 55 SE) and lowest in 2013 (149 no. m-3 ± 13). The species composition of communities, determined via hierarchical cluster analysis and indicator species analysis, produced six distinct communities based on season and location. The winter community, characterized by warm-water indicator species including Mesocalanus tenuicornis, Calanus pacificus, and Corycaeus anglicus, diverged into four communities throughout the spring and summer. The first spring community, characterized by copepods with affinities for lower salinities, occurred sound-wide. The second spring community, comprised of planktonic larvae, appeared sporadically in PWS bays in 2011-2013. Spring and summer open water stations were defined by the presence of large calanoid copepods. A summer community including the most abundant taxa was common in 2010 and 2011, absent in 2013, then sporadically appeared in 2014 and 2015 suggesting interannual variability of zooplankton assemblages. The zooplankton community shifted to a uniform assemblage characterized by cnidarians in the early autumn. Community assemblages showed significant correlations to a set of environmental variables including SST, mixed layer depth

  3. Water Browning Influences the Behavioral Effects of Ultraviolet Radiation on Zooplankton

    Directory of Open Access Journals (Sweden)

    Raoul Wolf

    2018-03-01

    Full Text Available In the last decades, limnic water bodies in the Northern hemisphere have experienced a noticeable browning, i.e., increasing levels of dissolved organic matter (DOM. While the effects on primary producers is usually considered negative (light attenuation, zooplankton is thought to benefit from increased DOM, which absorbs harmful ultraviolet radiation (UVR. However, behavioral alterations due to browning in zooplankton have not yet been studied. We investigated the effects of a DOM gradient, alone and in combination with UVR, on the swimming behavior of Daphnia magna. Making use of a computer-controlled imaging system, we repeatedly filmed individuals over 6 h and analyzed the video material to unravel effects on exploration behavior and other motility patterns. The results show that increasing DOM buffers the detrimental effects of UVR on swimming behavior. This is likely due to attenuation of UVR by DOM. Interestingly, DOM also raised the overall swimming activity independent of UVR exposure. Our findings highlight the importance of DOM in freshwater systems, not only because of its physico-chemical properties, but also due to its higher-level effects on zooplankton communities.

  4. Fishery survey, benthic organism, and zooplankton data collected using trawls and tows from the EASTWARD and other platforms in the North Atlantic Ocean and Others from 1980-01-16 to 1984-03-14 (NODC Accession 8500245)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fishery survey, fishing duration and other benthic organism data from unknown and other platforms from North Atlantic Ocean was collected over four years between...

  5. Diurnal variation of zooplankton in Malad creek, Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Nair, V.R.; Desai, B.N.

    stock and total population were higher in night than in day collections. Abundance and diversity of zooplankton were directly correlated to the prevailing tide and pollution load. Copepods formed the predominant group followed by decapods, gastropods...

  6. Dredging induced changes in zooplankton community and water ...

    African Journals Online (AJOL)

    user

    water characteristics and zooplankton community structure in Dal Lake. An assessment was done ... et al., 2007; Zhang et al., 2010). In aquatic ecosystems, .... generally high in fine grain sediment (Fisher et al., 1982;. Valiela, 1995). In post ...

  7. Understanding cyanobacteria-zooplankton interactions in a more eutrophic world

    NARCIS (Netherlands)

    Ger, K.A.; Hansson, L.; Lurling, M.F.L.L.W.

    2014-01-01

    1.We review and update recent observations of cyanobacteria–zooplankton interactions, identify theoretical and methodological limitations and evaluate approaches necessary for understanding the effects of increasing cyanobacterial blooms on plankton dynamics. 2.The emphasis on oversimplified studies

  8. Assessment of Zooplankton Community Structure of the Bahir Dar ...

    African Journals Online (AJOL)

    In general, species richness, evenness, and diversity increased as average abundance increased in the littoral zones of the lake. The dominant zooplankton were Bosmina longirostris, Daphnia lumholtzi, Thermodiaptomus galebi, Thermocyclops ethiopiensis, Diaphanosoma sarsi, Keratella sp., Brachionus sp., Filinia sp.

  9. impact of physicochemical factors on zooplankton species richness

    African Journals Online (AJOL)

    DR. AMINU

    This study revealed that physicochemical fluctuations was negative impact on the zooplankton species ... of convergence of wastewater streams, of which Jakara River carries ..... Discharge on Physicochemical Parameters and Some Heavy ...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Ramaiah, Neelam

    spinicauda) dominated the copepod community. Four species of chaetognaths were found in the area with predominance of Sagitta bedoti. Among the penaeid larvae Metapenaeus offinis was the most common species. Population of omnivores dominated the zooplankton...

  11. 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.

    are linked to bioaccumulation. The biological concentration factor and metal contents in zooplankton is appreciably varied for all the elements except for iron and zinc. The above findings clearly indicates the importance of bioavailability of metals...

  12. Dynamics of the zooplankton assemblage of Ojirami Reservoir, Edo ...

    African Journals Online (AJOL)

    Zooplankton form an important trophic link between phytoplankton and fish in ... with water temperature and water level; and positive with alkalinity, free CO2 and phosphate. The study revealed low pollution indicator species in the reservoir ...

  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. Diversity and seasonal variation of zooplankton of Lake Hlan ...

    African Journals Online (AJOL)

    SARAH

    2016-06-30

    Jun 30, 2016 ... The taxonomic composition and the species ... Keywords: Biodiversity; Community structure; Hydrological season; Zooplankton .... Table 1: Seasonal change in recorded environmental parameters ..... reproduction, growth and life duration (Fernandez de .... Spatial temporal patterns and relationships with.

  15. Zooplankton composition in Dharamtar creek adjoining Bombay harbour

    Digital Repository Service at National Institute of Oceanography (India)

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

    bedoti was the true inhabitant. In general zooplankton production indicated 1.5 fold increase towards the upper reaches of the creek where salinity variations were drastic. A more diversified faunal assemblage of oceanic and neritic species characterised...

  16. Zooplankton composition of the Kalpeni and Agatti atolls, Lakshadweep archiplago

    Digital Repository Service at National Institute of Oceanography (India)

    Achuthankutty, C.T.; Nair, S.R.S.; Haridas, P.; Madhupratap, M.

    Composition of zooplankton in the lagoons was quite different from that of the sea and to a large extent, was independent of oceanic influence While copepods were dominant in the sea, meroplankton, particularly brachyuran zoeae constituted...

  17. Zooplankton abundance in the River Kars, Northeast Turkey: Impact ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... Turkey: Impact of environmental variables. H. Özbay1* and ... in the river. Key words: River Kars, zooplankton, running water, environmental factors. ..... tergestina (Branchiopoda: Onychopoda) in Guanabara Bay, Brazil. Braz.

  18. Grazing by Zooplankton on Diazotrophs in the Amazon River Plume and Western Tropical North Atlantic

    Science.gov (United States)

    Conroy, B.; Steinberg, D. K.; Song, B.; Foster, R.

    2016-02-01

    Organisms capable of fixing di-nitrogen (N2), known as diazotrophs, are important primary producers and a potentially significant source for new nitrogen entering the planktonic food web. However, limited evidence exists for zooplankton grazing on diazotrophs compared to other primary producers. In the western tropical North Atlantic Ocean (WTNA), the Amazon River plume creates a niche for symbiotic diatom-diazotroph associations (DDAs) which can form large blooms. In adjacent non-plume-influenced waters, the colonial cyanobacterium Trichodesmium is abundant. In order to reveal zooplankton-diazotroph grazing interactions and determine the fate of newly fixed nitrogen, gut contents of zooplankton captured in these two regions were compared based on quantitative PCR (qPCR) assay of nitrogenase genes (nifH), and their microbiomes compared using next generation sequencing (NGS) analysis of 16S rRNA genes. We sampled individual copepods from discrete depth intervals (0-25m and 25-50m) and in two size classes (0.5-1mm and 1-2mm) for analysis. A modified DNA extraction protocol was developed and 54 extracts were used as templates in nifH qPCR assays for the larger size fraction diazotrophs (>10µm): Trichodesmium, and Hemiaulus or Rhizosolenia (diatoms)-Richelia (diazotroph) associations. Copepod gut content nifH copies ranged from 1.6 to 13.6 copies individual-1 for the assay targeting the Hemiaulus-Richelia DDA and from 1.1 to 3.0 copies individual-1 for Trichodesmium. 16S NGS conducted on 35 extracts with an Ion Torrent PGM and mothur revealed that cyanobacteria sequences accounted for up to 20% of sequences per extract. Our results show that both DDAs and Trichodesmium are prey for zooplankton, and that new nitrogen moves through the food web via these grazing interactions. These interactions should be considered in future explorations of the global ocean nitrogen cycle.

  19. 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.

  20. Procedures Involved in Radioecological Studies with Marine Zooplankton

    International Nuclear Information System (INIS)

    Fowler, S.W.; Small, L.F.

    1976-01-01

    Various procedures in marine radio ecological experiments with zooplankton are considered in the light of the possibility of establishing reference methods for marine radiobiological studies. Methods for collection, handling and maintenance prior to and during experiments are suggested for various types of zooplankton. The importance of physiological and physicochemical parameters are discussed in the context of the experimental design with the aim of achieving comparable results among workers involved in this field of research. (author)

  1. The conceptual model of organization social responsibility

    OpenAIRE

    LUO, Lan; WEI, Jingfu

    2014-01-01

    With the developing of the research of CSR, people more and more deeply noticethat the corporate should take responsibility. Whether other organizations besides corporatesshould not take responsibilities beyond their field? This paper puts forward theconcept of organization social responsibility on the basis of the concept of corporate socialresponsibility and other theories. And the conceptual models are built based on theconception, introducing the OSR from three angles: the types of organi...

  2. Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs?

    Directory of Open Access Journals (Sweden)

    T. A. S. V. Paes

    Full Text Available Abstract The aim of our study was to assess whether cyanotoxins (microcystins can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers. Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001, but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = – 0.01; P > 0.01 with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001. The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers. These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

  3. Putting "Organizations" into an Organization Theory Course: A Hybrid CAO Model for Teaching Organization Theory

    Science.gov (United States)

    Hannah, David R.; Venkatachary, Ranga

    2010-01-01

    In this article, the authors present a retrospective analysis of an instructor's multiyear redesign of a course on organization theory into what is called a hybrid Classroom-as-Organization model. It is suggested that this new course design served to apprentice students to function in quasi-real organizational structures. The authors further argue…

  4. Fine-scale distribution of zooplankton is linked to phytoplankton species composition and abundance in a North Norwegian fjord system

    Science.gov (United States)

    Norrbin, F.; Priou, P. D.; Varela, A. P.

    2016-02-01

    We studied the influence of dense layers of phytoplankton and aggregates on shaping the vertical distribution of zooplankton in a North Norwegian fjord using a Video Plankton Recorder (VPR). This instrument provided fine-scale vertical distribution (cm-m scale) of planktonic organisms as well as aggregates of marine snow in relation to environmental conditions. At the height - later stage of the spring phytoplankton bloom in May, the outer part of the fjord was dominated by Phaeocystis pouchetii, while diatoms (Chaetoceros spp.) were dominating in the innermost basin. Small copepods species like Pseudocalanus spp., Microsetella norvegica, and Oithona spp. prevailed over larger copepod species in the inner part of the fjord whereas the outer part was dominated by large copepods like Calanus finmarchicus. While the zooplankton where spread out over the water column during the early stage of the bloom, in May they were linked to the phytoplankton vertical distribution and in the winter situation they were found in deeper waters. Herbivorous zooplankton species were affected by phytoplankton species composition; C. finmarchicus and Pseudocalanus spp. avoided the dense layer of P. pouchetii while herbivorous zooplankton matched the distribution of the diatom-dominated bloom. Small, omnivorous copepod species like Microsetella sp., Oithona sp. and Pseudocalanus sp. were often associated with dense layers of snow aggregates. This distribution may provide a shelter from predators as well as a food source. Natural or anthropogenic-induced changes in phytoplankton composition and aggregate distribution may thus influence food-web interactions.

  5. Metal stress in zooplankton diapause production: post-hatching response.

    Science.gov (United States)

    Aránguiz-Acuña, Adriana; Pérez-Portilla, Pablo

    2017-04-01

    Aquatic organisms commonly respond to harsh conditions by forming diapausing stages, which enable populations to survive adverse periods forming egg banks. Production of diapausing eggs is frequently observed in monogonont rotifers, previously changing from asexual to partial sexual reproduction (mixis). In despite that zooplankton are frequently used in ecotoxicological assessment because of their sensitivity to various toxicants and their important role in the ecosystems, toxicity evaluations often consider the directly exposed population produced by parthenogenetic reproduction, exclusively. We assessed experimentally effects of exposure to metals on mixis delay and fitness of hatchlings of the rotifer Brachionus plicatilis obtained from a brackish water lagoon with high metal content, especially copper. We show that sub-lethal concentrations of copper affected traits related to sexual reproduction and diapausing egg production in the rotifer. Copper addition did not delay the start of mixis, suggesting that rapid initiation of mixis is promoted in risky environments, according to the hypothesis of mixis as an escape strategy. Higher investment in mixis was obtained when individuals were exposed to metal. Addition of copper negatively affected the hatching success of diapausing eggs and performance of hatchlings. Nevertheless, these effects were greater for individuals formed in non-metal conditions, suggesting an adaptive advantage of populations from natural sediments exposed to copper. These results highlight the ecological and evolutionary consequences of the presence of metals in freshwater environments by modulating diapause adaptive efficacy and the selective process in egg banks.

  6. 210Po/210Pb dynamics in relation to zooplankton biomass and trophic conditions during an annual cycle in northwestern Mediterranean coastal waters.

    Science.gov (United States)

    Färber Lorda, Jaime; Fowler, Scott W; Miquel, Juan-Carlos; Rodriguez y Baena, Alessia; Jeffree, Ross A

    2013-01-01

    Monthly sampling in northwestern Mediterranean coastal waters was undertaken to better understand the relationship between zooplankton biomass and the cycling of the natural radionuclide (210)Po/(210)Pb pair during a one-year period (October 1995-November 1996). In conjunction with mesozooplankton collections and (210)Po/(210)Pb measurements in seawater, zooplankton and their fecal pellets, the biochemical composition of particulate organic matter (POM) was also examined at three depths (0, 20 and 50 m) as an indicator of trophic conditions. During May 1996, a strong zooplankton "bloom" was observed which was preceded by a prolonged increase in POM (protein + carbohydrates + lipids) starting at the end of March, and further demonstrated by a concomitant increase in the concentration of smaller particles, two features that are typical of mesotrophic waters. Simultaneous measurements of (210)Po in sea water and zooplankton showed an inverse trend between these two parameters during the sampling period, with the two lowest (210)Po concentrations in the dissolved phase of seawater coincident with the highest radionuclide concentrations in the zooplankton; however, this apparent relationship was not statistically significant over the entire year. Freshly excreted mesozooplankton and salp fecal pellets, which have been strongly implicated in the removal and downward transport of these radionuclides from the upper water column, contained (210)Po and (210)Pb levels ranging from 175 to 878 and 7.5-486 Bq kg(-1) dry weight, respectively. Salp pellets contained 5 and 10 times more (210)Po and (210)Pb than in fecal pellets produced by mixed zooplankton, a finding most likely related to their different feeding strategies. During the zooplankton biomass peak observed in May, the (210)Po concentration in zooplankton was at a minimum; however, in contrast to what has been reported to occur in some open sea oligotrophic waters, over the year no statistically significant inverse

  7. Safety Cultural Competency Modeling in Nuclear Organizations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sa Kil; Oh, Yeon Ju; Luo, Meiling; Lee, Yong Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The nuclear safety cultural competency model should be supplemented through a bottom-up approach such as behavioral event interview. The developed model, however, is meaningful for determining what should be dealt for enhancing safety cultural competency of nuclear organizations. The more details of the developing process, results, and applications will be introduced later. Organizational culture include safety culture in terms of its organizational characteristics.

  8. A STRATEGIC MANAGEMENT MODEL FOR SERVICE ORGANIZATIONS

    OpenAIRE

    Andreea ZAMFIR

    2013-01-01

    This paper provides a knowledge-based strategic management of services model, with a view to emphasise an approach to gaining competitive advantage through knowledge, people and networking. The long-term evolution of the service organization is associated with the way in which the strategic management is practised.

  9. Expanding on Successful Concepts, Models, and Organization

    Science.gov (United States)

    If the goal of the AEP framework was to replace existing exposure models or databases for organizing exposure data with a concept, we would share Dr. von Göetz concerns. Instead, the outcome we promote is broader use of an organizational framework for exposure science. The f...

  10. 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.

  11. Bioavailability and uptake of smelter emissions in freshwater zooplankton in northeastern Washington, USA lakes using Pb isotope analysis and trace metal concentrations.

    Science.gov (United States)

    Child, A W; Moore, B C; Vervoort, J D; Beutel, M W

    2018-07-01

    The upper Columbia River and associated valley systems are highly contaminated with metal wastes from nearby smelting operations in Trail, British Columbia, Canada (Teck smelter), and to a lesser extent, Northport, Washington, USA (Le Roi smelter). Previous studies have investigated depositional patterns of airborne emissions from these smelters, and documented the Teck smelter as the primary metal contamination source. However, there is limited research directed at whether these contaminants are bioavailable to aquatic organisms. This study investigates whether smelter derived contaminants are bioavailable to freshwater zooplankton. Trace metal (Zn, Cd, As, Sb, Pb and Hg) concentrations and Pb isotope compositions of zooplankton and sediment were measured in lakes ranging from 17 to 144 km downwind of the Teck smelter. Pb isotopic compositions of historic ores used by both smelters are uniquely less radiogenic than local geologic formations, so when zooplankton assimilate substantial amounts of smelter derived metals their compositions deviate from local baseline compositions toward ore compositions. Sediment metal concentrations and Pb isotope compositions in sediment follow significant (p < 0.001) negative exponential and sigmoidal patterns, respectively, as distance from the Teck smelting operation increases. Zooplankton As, Cd, and Sb contents were related to distance from the Teck smelter (p < 0.05), and zooplankton Pb isotope compositions suggest As, Cd, Sb and Pb from historic and current smelter emissions are biologically available to zooplankton. Zooplankton from lakes within 86 km of the Teck facility display isotopic evidence that legacy ore pollution is biologically available for assimilation. However, without water column data our study is unable to determine if legacy contaminants are remobilized from lake sediments, or erosional pathways from the watershed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Emergent organization in a model market

    Science.gov (United States)

    Yadav, Avinash Chand; Manchanda, Kaustubh; Ramaswamy, Ramakrishna

    2017-09-01

    We study the collective behaviour of interacting agents in a simple model of market economics that was originally introduced by Nørrelykke and Bak. A general theoretical framework for interacting traders on an arbitrary network is presented, with the interaction consisting of buying (namely consumption) and selling (namely production) of commodities. Extremal dynamics is introduced by having the agent with least profit in the market readjust prices, causing the market to self-organize. In addition to examining this model market on regular lattices in two-dimensions, we also study the cases of random complex networks both with and without community structures. Fluctuations in an activity signal exhibit properties that are characteristic of avalanches observed in models of self-organized criticality, and these can be described by power-law distributions when the system is in the critical state.

  13. Intraspecific Autochthonous and Allochthonous Resource Use by Zooplankton in a Humic Lake during the Transitions between Winter, Summer and Fall.

    Directory of Open Access Journals (Sweden)

    Martin Berggren

    Full Text Available Seasonal patterns in assimilation of externally produced, allochthonous, organic matter into aquatic food webs are poorly understood, especially in brown-water lakes. We studied the allochthony (share biomass of terrestrial origin in cladoceran, calanoid and cyclopoid micro-crustacean zooplankton from late winter to fall during two years in a small humic lake (Sweden. The use of allochthonous resources was important for sustaining a small population of calanoids in the water column during late winter. However, in summer the calanoids shifted to 100% herbivory, increasing their biomass several-fold by making efficient use of the pelagic primary production. In contrast, the cyclopoids and cladocerans remained at high levels of allochthony throughout the seasons, both groups showing the mean allochthony of 0.56 (range in mean 0.17-0.79 and 0.34-0.75, for the respective group, depending on model parameters. Our study shows that terrestrial organic matter can be an important resource for cyclopoids and cladocerans on an annual basis, forming a significant link between terrestrial organic matter and the higher trophic levels of the food web, but it can also be important for sustaining otherwise herbivorous calanoids during periods of low primary production in late winter.

  14. Zooplankton data: Vertical distributions of zooplankton in the Norweigian and Greenland Seas during summer, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Lane, P.V.Z.; Smith, S.L.; Schwarting, E.M.

    1993-08-01

    Recent studies of zooplankton populations in the Greenland Sea have focused on processes at the Marginal Ice Zone (MIZ) and the areas immediately adjacent to it under the ice and in open water. These studies have shown a relatively short period of intense secondary productivity which is closely linked temporally and spatially to phytoplankton blooms occurring near the ice edge in spring and early summer. During the summer of 1989 we participated in a project focusing on benthic and water column processes in the basins of the Norwegian and Greenland Seas. This study allowed us to compare biological processes at the MIZ with those occurring in the open waters of the Greenland Sea, and to compare processes at both of these locations with those in the Norwegian Sea. The data presented in this report are the results of zooplankton net tows covering the upper 1000 meters of the water column over the Norwegian Sea basin and the Greenland Sea basin, and the upper 500 meters of open water adjacent to the MIZ in the Greenland Sea. Sampling was conducted between 12 and 29 July 1989.

  15. Integrated modelling of two xenobiotic organic compounds

    DEFF Research Database (Denmark)

    Lindblom, Erik Ulfson; Gernaey, K.V.; Henze, Mogens

    2006-01-01

    This paper presents a dynamic mathematical model that describes the fate and transport of two selected xenobiotic organic compounds (XOCs) in a simplified representation. of an integrated urban wastewater system. A simulation study, where the xenobiotics bisphenol A and pyrene are used as reference...... compounds, is carried out. Sorption and specific biological degradation processes are integrated with standardised water process models to model the fate of both compounds. Simulated mass flows of the two compounds during one dry weather day and one wet weather day are compared for realistic influent flow...... rate and concentration profiles. The wet weather day induces resuspension of stored sediments, which increases the pollutant load on the downstream system. The potential of the model to elucidate important phenomena related to origin and fate of the model compounds is demonstrated....

  16. Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth

    KAUST Repository

    Coello-Camba, A.; Llabré s, M.; Duarte, Carlos M.; Agusti, Susana

    2017-01-01

    Warming over Antarctica is leading to changes in the zooplankton communities inhabiting the Southern Ocean. It has been observed that zooplankton not only regulates phytoplankton through grazing, but also through the recycling of nutrients that are essential for phytoplankton growth. In this way, the effects of warming on zooplankton populations will change the amount or proportion at which recycled nutrients are restored. To estimate how the recycled nutrients released by zooplankton populations, dominated by krill (Euphausia superba), amphipods or copepods, affect the phytoplankton uptake and communities, we performed four incubation experiments: two close to the Antarctic Peninsula and two at the Southern Atlantic Ocean. Our results showed a stimulating effect of the addition of metabolites on ammonia removal rates and on the net growth of phytoplankton communities, with different responses amongst the different phytoplankton groups. According to our results, phytoplankton net growth and community composition may be altered if this relevant source of nutrients is lost due to projected changes in the abundance or distribution of these zooplankton populations.

  17. Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth

    KAUST Repository

    Coello-Camba, A.

    2017-04-24

    Warming over Antarctica is leading to changes in the zooplankton communities inhabiting the Southern Ocean. It has been observed that zooplankton not only regulates phytoplankton through grazing, but also through the recycling of nutrients that are essential for phytoplankton growth. In this way, the effects of warming on zooplankton populations will change the amount or proportion at which recycled nutrients are restored. To estimate how the recycled nutrients released by zooplankton populations, dominated by krill (Euphausia superba), amphipods or copepods, affect the phytoplankton uptake and communities, we performed four incubation experiments: two close to the Antarctic Peninsula and two at the Southern Atlantic Ocean. Our results showed a stimulating effect of the addition of metabolites on ammonia removal rates and on the net growth of phytoplankton communities, with different responses amongst the different phytoplankton groups. According to our results, phytoplankton net growth and community composition may be altered if this relevant source of nutrients is lost due to projected changes in the abundance or distribution of these zooplankton populations.

  18. Interannual abundance changes of gelatinous carnivore zooplankton unveil climate-driven hydrographic variations in the Iberian Peninsula, Portugal.

    Science.gov (United States)

    D'Ambrosio, Mariaelena; Molinero, Juan C; Azeiteiro, Ulisses M; Pardal, Miguel A; Primo, Ana L; Nyitrai, Daniel; Marques, Sónia C

    2016-09-01

    The persistent massive blooms of gelatinous zooplankton recorded during recent decades may be indicative of marine ecosystem changes. In this study, we investigated the potential influence of the North Atlantic climate (NAO) variability on decadal abundance changes of gelatinous carnivore zooplankton in the Mondego estuary, Portugal, over the period 2003-2013. During the 11-year study, the community of gelatinous carnivores encompassed a larger diversity of hydromedusae than siphonophores; the former dominated by Obelia spp., Lizzia blondina, Clythia hemisphaerica, Liriope tetraphylla and Solmaris corona, while the latter dominated by Muggiaea atlantica. Gelatinous carnivore zooplankton displayed marked interannual variability and mounting species richness over the period examined. Their pattern of abundance shifted towards larger abundances ca. 2007 and significant phenological changes. The latter included a shift in the mean annual pattern (from unimodal to bimodal peak, prior and after 2007 respectively) and an earlier timing of the first annual peak concurrent with enhanced temperatures. These changes were concurrent with the climate-driven environmental variability mainly controlled by the NAO, which displayed larger variance after 2007 along with an enhanced upwelling activity. Structural equation modelling allowed depicting cascading effects derived from the NAO influence on regional climate and upwelling variability further shaping water temperature. Such cascading effect percolated the structure and dynamics of the community of gelatinous carnivore zooplankton in the Mondego estuary. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Diurnal variation in zooplankton in the Zuari Estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Padmavati, G.; Goswami, S.C.; Vidya, P.S.

    Variations in zooplankton biomass and population density in relation to the prevailing hydrographical conditions were studied in Zuari Estuary, Goa. The physico-chemical parameters showed limited variations. Zooplankton biomass was relatively more...

  20. 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.

    Diel variations in zooplankton biomass, common groups and proximate composition zooplankton at stations between Vengurla to Ratnagiri, along west coast of India were studied. Higher biomass values were obtained for the night samples (av = 80 ml/100...

  1. Effect of tide on the variability of zooplankton in the nearshore waters of Thal, Maharashtra

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N; Nair, V.R.; Krishnakumari, L; Desai, B.N

    Quantitative and qualitative difference in zooplankton in relation to the tide were studied along 3 transects located off Thal, Maharashtra, India during Feb. 1980 to Jan. 1981. Variation in zooplankton biomass for the flood and ebb period were 2...

  2. A study on the zooplankton of the Burhabalanga Estuary, Orissa Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, Neelam; Chatterji, A.; Madhupratap, M.

    Annual variations in the zooplankton biomass and composition during 1991-92 were studied from the inshore, mouth and upstream regions of the Burhabalanga Estuary located in the Orissa Coast (India). Zooplankton biomass was maximum at all...

  3. NODC Standard Format Marine Zooplankton (F124) Data (1965-1983) (NODC Accession 0014196)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data type contains data from sampling and analysis of marine zooplankton. Information on zooplankton abundance, distribution and productivity derived from these...

  4. Production and associations of zooplankton in estuarine and nearshore waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.

    Zooplankton production in the Zuari and Mandovi estuaries indicated 2 peaks-one in November and another in March/April. In the nearshore waters very high value of zooplankton biomass was observed in April associated with Trichodesmium bloom. Mean...

  5. Interactions of phytoplankton, zooplankton and microorganisms

    Science.gov (United States)

    Pomeroy, L. R.; Paffenhöfer, G.-A.; Yoder, J. A.

    We present evidence that there are significant interactions between heterotrophic microorganisms, doliolids and Fritillaria within intrusions of nutrient-rich Gulf Stream water stranding on the continental shelf. During the summer of 1981 cold, nutrient-rich water from below the surface of the Gulf Stream was repeatedly intruded and stranded on the continental shelf off northeastern Florida. On August 6 old, stranded Gulf Stream water depleted of nitrate occupied the lower layer on the outer shelf. The upper water was continental shelf water, older but of undefined age. On August 6 free-living bacteria were >10 6ml -1 everywhere at all depths, an order of magnitude greater than normal bacterial numbers on the northeastern Florida continental shelf. Over 10 days the numbers of free bacteria doubled while bacteria attached to particles increased by a factor of four. The adenylate/chlorophyll ratio showed that phytoplankton dominated the lower layers of intruded water, while the surface water became increasingly dominated by heterotrophic microorganisms (bacteria and protozoa) over 10 days. There were significant, negative correlations between bacteria and doliolids and between bacteria and Fritillaria. Regions of maximum bacterial numbers did not coincide with locations of salp swarms. The increased numbers of bacteria at all depths in a highly stratified system in which most phytoplankton are in the lower layer suggests a diverse source of bacterial growth substrates, some of which involve zooplankton as intermediaries. Production of autotrophs is more than twice that of microheterotrophs on average, but because of their differential distribution, microheterotrophs are the dominant biomass in much of the surface water and may be significant in energy flux to metazoan consumers as well as competitors for mutually useable sources of nutrition.

  6. Feeding on dispersed vs. aggregated particles: The effect of zooplankton feeding behavior on vertical flux

    DEFF Research Database (Denmark)

    Koski, Marja; Boutorh, Julia; De La Rocha, Christina L.

    2017-01-01

    Zooplankton feeding activity is hypothesized to attenuate the downward flux of elements in the ocean. We investigated whether the zooplankton community composition could influence the flux attenuation, due to the differences of feeding modes (feeding on dispersed vs. aggregated particles) and of ......Zooplankton feeding activity is hypothesized to attenuate the downward flux of elements in the ocean. We investigated whether the zooplankton community composition could influence the flux attenuation, due to the differences of feeding modes (feeding on dispersed vs. aggregated particles...

  7. Modelling the behaviour of organic degradation products

    International Nuclear Information System (INIS)

    Cross, J.E.; Ewart, F.T.; Greenfield, B.F.

    1989-03-01

    Results are presented from recent studies at Harwell which show that the degradation products which are formed when certain organic waste materials are exposed to the alkaline conditions typical of a cementitious environment, can enhance the solubility of plutonium, even at pH values as high as 12, by significant factors. Characterisation of the degradation products has been undertaken but the solubility enhancement does not appear to be related to the concentration of any of the major organic species that have been identified in the solutions. While it has not been possible to identify by analysis the organic ligand responsible for the increased solubility of plutonium, the behaviour of D-Saccharic acid does approach the behaviour of the degradation products. The PHREEQE code has been used to simulate the solubility of plutonium in the presence of D-Saccharic acid and other model degradation products, in order to explain the solubility enhancement. The extrapolation of the experimental conditions to the repository is the major objective, but in this work the ability of a model to predict the behaviour of plutonium over a range of experimental conditions has been tested. (author)

  8. Flow disturbances generated by feeding and swimming zooplankton

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, Haisong; Goncalves, R. J.

    2014-01-01

    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...... 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...

  9. River discharge as a major driving force on spatial and temporal variations in zooplankton biomass and community structure in the Godavari estuary India.

    Science.gov (United States)

    Venkataramana, V; Sarma, V V S S; Matta Reddy, Alavala

    2017-08-28

    Variability in horizontal zooplankton biomass distribution was investigated over 13 months in the Godavari estuary, along with physical (river discharge, temperature, salinity), chemical (nutrients, particulate organic matter), biological (phytoplankton biomass), and geological (suspended matter) properties to examine the influencing factors on their spatial and temporal variabilities. The entire estuary was filled with freshwater during peak discharge period and salinity near zero, increased to ~ 34 psu during dry period with relatively high nutrient levels during former than the latter period. Due to low flushing time ( 500 mg L -1 ) during peak discharge period, picoplankton (cyanophyceae) contributed significantly to the phytoplankton biomass (Chl-a) whereas microplankton and nanoplankton (bacillariophyceae, and chlorophyceae) during moderate and mostly microplankton during dry period. Zooplankton biomass was the lowest during peak discharge period and increased during moderate followed by dry period. The zooplankton abundance was controlled by dead organic matter during peak discharge period, while both phytoplankton biomass and dead organic matter during moderate discharge and mostly phytoplankton biomass during dry period. This study suggests that significant modification of physico-chemical properties by river discharge led to changes in phytoplankton composition and dead organic matter concentrations that alters biomass, abundance, and composition of zooplankton in the Godavari estuary.

  10. Virtuous organization: A structural equation modeling approach

    Directory of Open Access Journals (Sweden)

    Majid Zamahani

    2013-02-01

    Full Text Available For years, the idea of virtue was unfavorable among researchers and virtues were traditionally considered as culture-specific, relativistic and they were supposed to be associated with social conservatism, religious or moral dogmatism, and scientific irrelevance. Virtue and virtuousness have been recently considered seriously among organizational researchers. The proposed study of this paper examines the relationships between leadership, organizational culture, human resource, structure and processes, care for community and virtuous organization. Structural equation modeling is employed to investigate the effects of each variable on other components. The data used in this study consists of questionnaire responses from employees in Payam e Noor University in Yazd province. A total of 250 questionnaires were sent out and a total of 211 valid responses were received. Our results have revealed that all the five variables have positive and significant impacts on virtuous organization. Among the five variables, organizational culture has the most direct impact (0.80 and human resource has the most total impact (0.844 on virtuous organization.

  11. Relationships among cyanobacteria, zooplankton and fish in sub-bloom conditions in the Sulejow Reservoir

    Directory of Open Access Journals (Sweden)

    Zbigniew Kaczkowski

    2017-01-01

    Full Text Available The occurrence of cyanobacteria is particularly characteristic of shallow eutrophic waters, and they often form massive ‘blooms’ that can affect aquatic invertebrates and fish. However, even a low abundance of cyanobacteria can be hazardous to aquatic organisms, due to the production of toxic metabolites. The aim of this study was to investigate the relationship between cyanobacteria and their toxicity (biological activity towards zooplankton and fish communities, when only low concentrations of cyanobacterial chlorophyll a (less than 20 μg L-1 are detected, i.e. in sub-bloom conditions. Measurements were performed in Sulejow Reservoir (Central Poland, a shallow, lowland, eutrophic reservoir, in which cyanobacterial blooms occur regularly. Fish were assessed using echo-sounding (distribution and by gillnetting (species composition. Simultaneously, zooplankton, cyanobacteria and physico-chemical characteristics were studied at 14 stations situated along hydroacoustic transects. Parameters that characterized the cyanobacteria (cyanobacterial chlorophyll a concentration, the number of 16S rRNA and the mcyA gene copies and microcystin (MC concentration were consistently correlated (based on a principal component analysis, and the highest values were found in the downstream region of the study area. This ‘cyano-complex’ was also positively correlated with oxygen concentration, pH and phosphate levels, but was negatively correlated with temperature and the concentrations of nitrates and nitrites. In Sulejow Reservoir in 2013 the biomass of large zooplankton filter feeders decreased along with increasing MC concentration and fish densities, while small filter feeders did not present such relationships with regards to fish densities. Fish abundance tended to decrease at stations with a lower abundance of cyanobacteria and with growing toxic genotype copies and MC concentration.

  12. Carbon sequestration capacity of sediments, algae, and zooplankton from fresh water aquaculture ponds.

    Science.gov (United States)

    Anikuttan, K K; Adhikari, S; Kavitha, M; Jayasankar, P

    2016-07-01

    The contribution of aquaculture and allied activities to the emission of green house gases and consequently to global warming is an emerging concern among environmentalists in the recent past. However, there exists ample scope for aquaculture activities to sequester carbon and thus compensate for the carbon emissions linked to aquaculture. This article attempts to elucidate the carbon sequestration capacity of sediments, algae, and zooplankton from fresh water aquaculture ponds. The percent organic carbon in the pond sediments ranged from 0.39 to 1.31 with an average value of 0.912 ± 0.321 whereas the carbon sequestration capacity ranged from 0.442 to 1.882 MgC/ha (1 Mg = 10(6) g) with an average value of 1.018 ± 0.447 MgC/ha. In the case of zooplankton and algae from pond, the percent organic carbon was 7.688 ± 0.196 and 2.354 ± 0.047, respectively, whereas the total estimated carbon burial rate was 0.009 ± 0.005 and 0.150 ± 0.003 MgC/ha, respectively. These findings are discussed with the previous reports available at present and are found to be in comparable ranges.

  13. Biochemical composition of zooplankton from the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Rao, T.S.S.; Matondkar, S.G.P.

    Protein was the dominant constituent in mixed zooplankton major planktonic groups and some common species collected from the Andaman Sea. Overall mean values, calculated as a percentage of dry weight, were 45,14 protein, 10.6 lipid, 4.2 carbohydrate...

  14. Zooplankton community structure and dynamics during the transition ...

    African Journals Online (AJOL)

    This study investigates the zooplankton community structure and dynamics of Kufena Rock Pool during the transition from dry season (March to April) to rainy season (May to June) in Zaria, Nigeria. Physicochemical parameters such as temperature, hydrogen ion concentration, electrical conductivity and total dissolved ...

  15. Meso-zooplankton movement through the newly constructed Mfolozi ...

    African Journals Online (AJOL)

    Results show that the beach spillway has facilitated recruitment into St Lucia from the ocean and the Mfolozi River. Further research is needed to ascertain what effect this recruitment has on long-term zooplankton community structure. Key words: iSimangaliso Wetland Park, relinkage, Mfolozi channel, ebb and flood tides, ...

  16. Aging of microplastics promotes their ingestion by marine zooplankton

    NARCIS (Netherlands)

    Vroom, Renske J.E.; Koelmans, Bart; Besseling, Ellen

    2017-01-01

    Microplastics (<5 mm) are ubiquitous in the marine environment and are ingested by zooplankton with possible negative effects on survival, feeding, and fecundity. The majority of laboratory studies has used new and pristine microplastics to test their impacts, while aging processes such as

  17. Studies on the distribution of gelatinous zooplankton in the ...

    African Journals Online (AJOL)

    spamer

    boundary to the system (Agenbag and Shannon 1988,. Largier and Boyd 2001), it is not considered to have a profound influence on the specific composition of regional zooplankton (Gibbons et al. 1995, Gibbons and Thibault-Botha 2002, but see Barange et al. 1992,. Emanuel et al. 1992). Indeed, it has been suggested.

  18. Effect of pig dung fertilizer on zooplankton production

    African Journals Online (AJOL)

    SARAH

    2014-12-29

    Dec 29, 2014 ... Key-words: pig dung, fertilization, zooplankton production. ... an already widespread practice in many Asian countries (fukusho, et al., ..... Elsevier Scientific Publishing Company,. New York ... Effect on Water Quality, pond productivity and. Growth of ... McQueen DJ, Johannes MRS, Post JR, Stewart TJ, Lean.

  19. The effect of some environmental factors on zooplankton community ...

    African Journals Online (AJOL)

    The zooplankton of Lake Qarun was studied January–December 2003. A total of 26 species was recorded, amongst which protozoa, primarily ciliophora, were most abundant (79% of the species total), followed by rotifera (13%) and copepoda (8%). The average density ranged from 965–1 452 l–1. The highest density (2 ...

  20. The crustacean zooplankton assemblage of a relatively pristine Utor ...

    African Journals Online (AJOL)

    The water quality and crustacean zooplankton of Utor River, a relatively pristine freshwater body in Edo State, Nigeria was investigated at four stations. The Utor River is slightly acidic, well oxygenated, oligotrophic and low in solids, conductivity, cations and heavy metals. A total of 380 individuals comprising eleven taxa ...

  1. Zooplankton assessment of Iyikpesu river Aragba- Orogun, Delta ...

    African Journals Online (AJOL)

    48.0 (39±9) mg CaCO3/L. All parameters were within permissible limits. Eighty– three (83) species of zooplankton belonging to five (5) taxonomic groups were identified. Rotifers contributed the highest number of taxa (36) followed by copepods ...

  2. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    Science.gov (United States)

    Cole, J.J.; Carpenter, S.R.; Kitchell, J.; Pace, M.L.; Solomon, C.T.; Weidel, B.

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ???20-40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread.

  3. Effects of Climate on the Zooplankton of the California Current

    Science.gov (United States)

    Lavaniegos, B. E.

    2007-05-01

    Almost six decades of sampling of the California Current system, carried out by the CalCOFI program (California Cooperative Fisheries Investigation) complemented by a decade of observations from the IMECOCAL program (Investigaciones Mexicanas de la Corriente de California), have revealed changing patterns in zooplankton abundances, species composition, and distributions over interannual through multidecadal time scales. Interannual changes associated with ENSO variability are manifested as strong but transitory perturbations in the mean annual cycle in seasonal abundances (and distributions) of particular species. An investigation of longer- term change, limited to the region off southern California, shows a persistent decline in zooplankton volumes (a proxy for overall biomass of macrozooplankton) between 1977 and 1998 that is considered to be a response to the well documented shift in basin-scale climate forcing that occurred in 1976-77. Further examination of this decline in zooplankton volumes indicates that it was due principally to the disappearance of several salp species after 1977. Other species and functional groups did not decline after the change in climate regime, while some species have followed persistent secular trends that appear to be associated more with the phenomenon of long-term global warming. Differences in the regional responses to climate change throughout the California Current system have also been observed recently in the spatial distribution of zooplankton biomass and changes in latitudinal ranges of certain species. For example, zooplankton biomass in the Baja California region show typical values for the 1997-98 El Niño that were followed by a decrease during the sharp transition to the cool La Niña conditions in 1999. This contrasts with the nearby region off southern California that was characterized by reduced biomass during the El Niño period and the subsequent recovery during the La Niña. Another regional contrast in

  4. Distribution of zooplankton populations within and adjacent to a thermal plume

    International Nuclear Information System (INIS)

    Evans, M.S.

    1981-01-01

    Zooplankton distributions in the 1-m stratum differed between ambient waters and the thermal plume of the Donald C. Cook Nuclear Power Plant. Zooplankton were most abundant in the warmest waters of the plume with the region of high densities extending over an approximate area of 0.2 to 0.3 km 2 . Water temperature was not a reliable indicator of alterations in zooplankton populations. Alterations were primarily due to upward vertical displacment of deep-living zooplankton. Large horizontal variability in zooplankton densities and use of conventional sampling procedures (vertically hauled nets, widely spaced stations) prevent traditionally designed monitoring programs from detecting such alterations. Zooplankton may experience indirect mortality losses in the plume if transfer of deep-living zooplankton to the surface layers makes them more visible to visual-feeding fish predators, and turbulences in the plume reduce zooplankters' ability to detect and avoid such predators. (auth)

  5. Rapid evolution of tolerance to road salt in zooplankton.

    Science.gov (United States)

    Coldsnow, Kayla D; Mattes, Brian M; Hintz, William D; Relyea, Rick A

    2017-03-01

    Organisms around the globe are experiencing novel environments created by human activities. One such disturbance of growing concern is the salinization of freshwater habitats from the application of road deicing salts, which creates salinity levels not experienced within the recent evolutionary history of most freshwater organisms. Moreover, salinization can induce trophic cascades and alter the structure of freshwater communities, but knowledge is still scarce about the ability of freshwater organisms to adapt to elevated salinity. We examined if a common zooplankton of freshwater lakes (Daphnia pulex) could evolve a tolerance to the most commonly used road deicing salt (sodium chloride, NaCl). Using a mesocosm experiment, we exposed freshwater communities containing Daphnia to five levels of NaCl (15, 100, 200, 500, and 1000 mg Cl -  L -1 ). After 2.5 months, we collected Daphnia from each mesocosm and raised them in the lab for three generations under low salt conditions (15 mg Cl -  L -1 ). We then conducted a time-to-death experiment with varying concentrations of NaCl (30, 1300, 1500, 1700, 1900 mg Cl -  L -1 ) to test for evolved tolerance. All Daphnia populations exhibited high survival when subsequently exposed to the lowest salt concentration (30 mg Cl -  L -1 ). At the intermediate concentration (1300 mg Cl -  L -1 ), however, populations previously exposed to elevated concentrations (i.e.100-1000 mg Cl -  L -1 ) had higher survival than populations previously exposed to natural background levels (15 mg Cl -  L -1 ). All populations survived poorly when subsequently exposed to the highest concentrations (1500, 1700, and 1900 mg Cl -  L -1 ). Our results show that the evolution of tolerance to moderate levels of salt can occur within 2.5 months, or 5-10 generations, in Daphnia. Given the importance of Daphnia in freshwater food webs, such evolved tolerance might allow Daphnia to buffer food webs from the impacts of freshwater

  6. An Organization's Extended (Soft) Competencies Model

    Science.gov (United States)

    Rosas, João; Macedo, Patrícia; Camarinha-Matos, Luis M.

    One of the steps usually undertaken in partnerships formation is the assessment of organizations’ competencies. Typically considered competencies of a functional or technical nature, which provide specific outcomes can be considered as hard competencies. Yet, the very act of collaboration has its specific requirements, for which the involved organizations must be apt to exercise other type of competencies that affect their own performance and the partnership success. These competencies are more of a behavioral nature, and can be named as soft-competencies. This research aims at addressing the effects of the soft competencies on the performance of the hard ones. An extended competencies model is thus proposed, allowing the construction of adjusted competencies profiles, in which the competency levels are adjusted dynamically according to the requirements of collaboration opportunities.

  7. Modeling photocurrent transients in organic solar cells

    International Nuclear Information System (INIS)

    Hwang, I; Greenham, N C

    2008-01-01

    We investigate the transient photocurrents of organic photovoltaic devices in response to a sharp turn-on of illumination, by numerical modeling of the drift-diffusion equations. We show that the photocurrent turn-on dynamics are determined not only by the transport dynamics of free charges, but also by the time required for the population of geminate charge pairs to reach its steady-state value. The dissociation probability of a geminate charge pair is found to be a key parameter in determining the device performance, not only by controlling the efficiency at low intensities, but also in determining the fate of charge pairs formed by bimolecular recombination at high intensities. Bimolecular recombination is shown to reduce the turn-on time at high intensities, since the typical distance traveled by a charge pair is reduced.

  8. Computational modeling of Metal-Organic Frameworks

    Science.gov (United States)

    Sung, Jeffrey Chuen-Fai

    In this work, the metal-organic frameworks MIL-53(Cr), DMOF-2,3-NH 2Cl, DMOF-2,5-NH2Cl, and HKUST-1 were modeled using molecular mechanics and electronic structure. The effect of electronic polarization on the adsorption of water in MIL-53(Cr) was studied using molecular dynamics simulations of water-loaded MIL-53 systems with both polarizable and non-polarizable force fields. Molecular dynamics simulations of the full systems and DFT calculations on representative framework clusters were utilized to study the difference in nitrogen adsorption between DMOF-2,3-NH2Cl and DMOF-2,5-NH 2Cl. Finally, the control of proton conduction in HKUST-1 by complexation of molecules to the Cu open metal site was investigated using the MS-EVB methodology.

  9. Climate-induced signatures in the zooplankton communities: a meta-analysis at a European scale.

    Directory of Open Access Journals (Sweden)

    Sónia Cotrim Marques

    2014-05-01

    Full Text Available Several recent studies have revealed the impacts of the climate variability in the dynamic of zooplankton in different estuarine ecosystems, imposing a need for more and continued global studies. Presently, there is a growing appreciation in international collaborations to compare and contrast estuarine ecosystem response to climate variability across geographical gradients, including long-term changes in zooplankton. We performed a meta-analysis comprising field data from 7 location (Mondego estuary-Portugal, Seine estuary- France, Sheldt estuary- Belgium, Kiel fjord - Germany, Gulf of Riga- Latvia, Gulf of Bothnia – Sweden and Finland Archipelagos. The use of climatic modes (e.g. NAO, ENSO has proven useful in investigating links between climatic variations and ecological patterns. Therefore, the main focus will be to test the influence of the NAO on abundance of organisms, key species, local environment and whether these relationships are generally positive, whether they are sensitive to methodological differences among studies, between taxonomic group and key species. The knowledge gained will contribute to quantitatively evaluate the multi-scale structure of climate and marine environment and to identify a set of environmental indicators to assess the estuarine ecosystem state and risks for ecological shifts.

  10. Trophic pathways of phytoplankton size classes through the zooplankton food web over the spring transition period in the north-west Mediterranean Sea

    Science.gov (United States)

    Hunt, Brian P. V.; Carlotti, François; Donoso, Katty; Pagano, Marc; D'Ortenzio, Fabrizio; Taillandier, Vincent; Conan, Pascal

    2017-08-01

    Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is necessary to understand food-web functioning and response to climate change. During the Deep Water formation Experiment (DEWEX), conducted in the north-west Mediterranean Sea in winter (February) and spring (April) of 2013, we investigated phytoplankton-zooplankton trophic links in contrasting oligotrophic and eutrophic conditions. Size fractionated particulate matter (pico-POM, nano-POM, and micro-POM) and zooplankton (64 to >4000 μm) composition and carbon and nitrogen stable isotope ratios were measured inside and outside the nutrient-rich deep convection zone in the central Liguro-Provencal basin. In winter, phytoplankton biomass was low (0.28 mg m-3) and evenly spread among picophytoplankton, nanophytoplankton, and microphytoplankton. Using an isotope mixing model, we estimated average contributions to zooplankton biomass by pico-POM, nano-POM, and micro-POM of 28, 59, and 15%, respectively. In spring, the nutrient poor region outside the convection zone had low phytoplankton biomass (0.58 mg m-3) and was dominated by pico/nanophytoplankton. Estimated average contributions to zooplankton biomass by pico-POM, nano-POM, and micro-POM were 64, 28 and 10%, respectively, although the model did not differentiate well between pico-POM and nano-POM in this region. In the deep convection zone, spring phytoplankton biomass was high (1.34 mg m-3) and dominated by micro/nano phytoplankton. Estimated average contributions to zooplankton biomass by pico-POM, nano-POM, and micro-POM were 42, 42, and 20%, respectively, indicating that a large part of the microphytoplankton biomass may have remained ungrazed.Plain Language SummaryThe grazing of zooplankton on algal phytoplankton is a critical step in the transfer of energy through all ocean food webs. Although microscopic, phytoplankton span an enormous size range. The smallest picophytoplankton are generally thought to be too

  11. Model for Railway Infrastructure Management Organization

    Directory of Open Access Journals (Sweden)

    Gordan Stojić

    2012-03-01

    Full Text Available The provision of appropriate quality rail services has an important role in terms of railway infrastructure: quality of infrastructure maintenance, regulation of railway traffic, line capacity, speed, safety, train station organization, the allowable lines load and other infrastructure parameters.The analysis of experiences in transforming the railway systems points to the conclusion that there is no unique solution in terms of choice for institutional rail infrastructure management modes, although more than nineteen years have passed from the beginning of the implementation of the Directive 91/440/EEC. Depending on the approach to the process of restructuring the national railway company, adopted regulations and caution in its implementation, the existence or absence of a clearly defined transport strategy, the willingness to liberalize the transport market, there are several different ways for institutional management of railway infrastructure.A hybrid model for selection of modes of institutional rail infrastructure management was developed based on the theory of artificial intelligence, theory of fuzzy sets and theory of multicriteria optimization.KEY WORDSmanagement, railway infrastructure, organizational structure, hybrid model

  12. The impact of fish predation and cyanobacteria on zooplankton size structure in 96 subtropical lakes.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    Full Text Available 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 zooplankton size was positively related to fish yield. The studied lakes were grouped into three types, namely, natural fishing lakes with low nutrient loading (Type1, planktivorous fish-dominated lakes (Type 2, and eutrophic lakes with high cyanobacterial biomass (Type 3. A marked difference in zooplankton size structure was found among these groups. The greatest mean zooplankton size was observed in Type 2 lakes, but zooplankton density was the lowest. Zooplankton abundance was highest in Type 3 lakes and increased with increasing cyanobacterial biomass. Zooplankton mean size was negatively correlated with cyanobacterial biomass. No obvious trends were found in Type 1 lakes. These results were reflected by the normalized biomass size spectrum, which showed a unimodal shape with a peak at medium sizes in Type 2 lakes and a peak at small sizes in Type 3 lakes. These results indicated a relative increase in medium-sized and small-sized species in Types 2 and 3 lakes, respectively. Our results suggested that fish predation might have a negative effect on zooplankton abundance but a positive effect on zooplankton size structure. High cyanobacterial biomass most likely caused a decline in the zooplankton size and encouraged the proliferation of small zooplankton. We suggest that both planktivorous fish and cyanobacteria have substantial effects on the shaping of zooplankton community, particularly in the lakes in the eastern plain along the Yangtze River where

  13. Project-matrix models of marketing organization

    OpenAIRE

    Gutić Dragutin; Rudelj Siniša

    2009-01-01

    Unlike theory and practice of corporation organization, in marketing organization numerous forms and contents at its disposal are not reached until this day. It can be well estimated that marketing organization today in most of our companies and in almost all its parts, noticeably gets behind corporation organization. Marketing managers have always been occupied by basic, narrow marketing activities as: sales growth, market analysis, market growth and market share, marketing research, introdu...

  14. Zooplankton - Study methods, importance and significant observations

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.

    density, shorter life span, drifting nature, high group/species diversity and different tolerance to the stress, they are being used as the indicator organisms for the physical, chemical and biological processes in the aquatic ecosystem. In the deeper...

  15. Carbon cycling and POC turnover in the mesopelagic zone of the ocean: Insights from a simple model

    Science.gov (United States)

    Anderson, Thomas R.; Tang, Kam W.

    2010-08-01

    Carbon budgets of the mesopelagic zone are poorly constrained, highlighting our lack of understanding of the biota that inhabit this environment and their role in the cycling and sequestering of carbon in the deep ocean. A simple food web model of the mesopelagic zone is presented that traces the turnover of particulate organic carbon (POC), supplied as sinking detritus, through to its respiration by the biota via three pathways: colonization and solubilization of detritus by attached bacteria, production of free-living bacteria following losses of solubilization products during particle degradation, and consumption by detritivorous zooplankton. The relative consumption of detritus by attached bacteria was initially specified as 76%, with the remaining 24% by detritivores. Highlighting an asymmetry between consumption and respiration, the resulting predicted share of total respiration due to bacteria was 84.7%, with detritivores accounting for just 6.6% (with 6.5% and 2.2% by bacterivores and higher zooplankton, respectively). Bacteria thus dominated respiration and thereby acted as the principal sink for POC supplied to the mesopelagic zone, whereas zooplankton mainly recycled carbon back to the base of the food web as detritus or dissolved organic carbon rather than respiring it to CO 2. Estimates of respiration are therefore not necessarily a reliable indicator of the relative roles of bacteria and zooplankton in consuming and processing POC in the mesopelagic zone of the ocean. The work highlighted a number of major unknowns, including how little we know in general about the dynamics and metabolic budgets of bacteria and zooplankton that inhabit the mesopelagic zone and, specifically, the degree to which the solubilized products of enzymatic hydrolysis of POC by attached bacteria are lost to the surrounding water, the magnitude and factors responsible for bacterial growth efficiency, the role of microbes in the nutrition of detritivores, and the recycling

  16. The Time Is Right to Focus on Model Organism Metabolomes

    Directory of Open Access Journals (Sweden)

    Arthur S. Edison

    2016-02-01

    Full Text Available Model organisms are an essential component of biological and biomedical research that can be used to study specific biological processes. These organisms are in part selected for facile experimental study. However, just as importantly, intensive study of a small number of model organisms yields important synergies as discoveries in one area of science for a given organism shed light on biological processes in other areas, even for other organisms. Furthermore, the extensive knowledge bases compiled for each model organism enable systems-level understandings of these species, which enhance the overall biological and biomedical knowledge for all organisms, including humans. Building upon extensive genomics research, we argue that the time is now right to focus intensively on model organism metabolomes. We propose a grand challenge for metabolomics studies of model organisms: to identify and map all metabolites onto metabolic pathways, to develop quantitative metabolic models for model organisms, and to relate organism metabolic pathways within the context of evolutionary metabolomics, i.e., phylometabolomics. These efforts should focus on a series of established model organisms in microbial, animal and plant research.

  17. Dynamics of the limnological features and diversity of zooplankton populations of the Cross River System SE Nigeria

    Directory of Open Access Journals (Sweden)

    Offem B. O.

    2009-12-01

    Full Text Available Physico-chemical factors and zooplankton diversity were investigated over a two year period in three regions along the 200 km length of Cross River. The objective of the study was to quantify the relative importance of local environmental conditions and diversity of the principal zooplankton species within sampling sites. Mean conductivity, TDS and chlorides were highest upriver with values 289 ± 198 µs·cm–1, 322.9 ± 101 mg·L–1, and 105.8 ± 77.3 mg·L–1 and lowest downriver with 123.5 ± 78.9 mg·L–1, 45.8 ± 23.7 mg·L–1 and 109 ± 89 µs·cm–1 respectively. Values of wet season water conductivity (406 ± 178 µs·cm–1, TDS (420.4 ± 267 mg·L–1, alkalinity (289.9 ± 34.7, total hardness (205.8 ± 37 mg·L–1, BOD (1.7 ± 0.2, chlorides (205.8 ± 37 and ammonium ions (0.2 ± 0.1 mg·L–1 were significantly higher than dry season values of 156 ± 78.5 µs·cm–1, 0.2 ± 0.1, 123.8 ± 15, 101.4 ± 87.9, 0.2 ± 0.1, 78.1 ± 34.8 and 0.1 ± 0.1 mg·L–1 respectively. Out of twenty seven (27 zooplankton species identified Cladocerans (Ceriodaphnia, Evadne, Alona sp. and Decapods (Lucifer, Penaeid nauphlius, and Hermit crab larva were the most diverse taxonomic group, while Tintinnopsis was the only Ciliate. Rainfall value was positively correlated with hydrological characteristics (size of river, flow velocity, water level, and transparency, which in turn determined values of physico-chemical properties and explained the observed seasonal and spatial changes in zooplankton diversity. Though water quality parameters were within the limits set by the World Health Organization (WHO and European Economic Community (EEC for good water, the changes in hydrological features of Cross River could be suspected to provide highly unstable aquatic habitat that could subsequently affect the stability of zooplankton and other aquatic organisms.

  18. Dynamics of the limnological features and diversity of zooplankton populations of the Cross River System SE Nigeria

    Directory of Open Access Journals (Sweden)

    B.O. Offem

    2009-12-01

    Full Text Available Physico-chemical factors and zooplankton diversity were investigated over a two year period in three regions along the 200 km length of Cross River. The objective of the study was to quantify the relative importance of local environmental conditions and diversity of the principal zooplankton species within sampling sites. Mean conductivity, TDS and chlorides were highest upriver with values 289 ± 198 µs·cm–1, 322.9 ± 101 mg·L–1, and 105.8 ± 77.3 mg·L–1 and lowest downriver with 123.5 ± 78.9 mg·L–1, 45.8 ± 23.7 mg·L–1 and 109 ± 89 µs·cm–1 respectively. Values of wet season water conductivity (406 ± 178 µs·cm–1, TDS (420.4 ± 267 mg·L–1, alkalinity (289.9 ± 34.7, total hardness (205.8 ± 37 mg·L–1, BOD (1.7 ± 0.2, chlorides (205.8 ± 37 and ammonium ions (0.2 ± 0.1 mg·L–1 were significantly higher than dry season values of 156 ± 78.5 µs·cm–1, 0.2 ± 0.1, 123.8 ± 15, 101.4 ± 87.9, 0.2 ± 0.1, 78.1 ± 34.8 and 0.1 ± 0.1 mg·L–1 respectively. Out of twenty seven (27 zooplankton species identified Cladocerans (Ceriodaphnia, Evadne, Alona sp. and Decapods (Lucifer, Penaeid nauphlius, and Hermit crab larva were the most diverse taxonomic group, while Tintinnopsis was the only Ciliate. Rainfall value was positively correlated with hydrological characteristics (size of river, flow velocity, water level, and transparency, which in turn determined values of physico-chemical properties and explained the observed seasonal and spatial changes in zooplankton diversity. Though water quality parameters were within the limits set by the World Health Organization (WHO and European Economic Community (EEC for good water, the changes in hydrological features of Cross River could be suspected to provide highly unstable aquatic habitat that could subsequently affect the stability of zooplankton and other aquatic organisms.

  19. Next generation sequencing reveals the hidden diversity of zooplankton assemblages.

    Directory of Open Access Journals (Sweden)

    Penelope K Lindeque

    Full Text Available BACKGROUND: Zooplankton play an important role in our oceans, in biogeochemical cycling and providing a food source for commercially important fish larvae. However, difficulties in correctly identifying zooplankton hinder our understanding of their roles in marine ecosystem functioning, and can prevent detection of long term changes in their community structure. The advent of massively parallel next generation sequencing technology allows DNA sequence data to be recovered directly from whole community samples. Here we assess the ability of such sequencing to quantify richness and diversity of a mixed zooplankton assemblage from a productive time series site in the Western English Channel. METHODOLOGY/PRINCIPLE FINDINGS: Plankton net hauls (200 µm were taken at the Western Channel Observatory station L4 in September 2010 and January 2011. These samples were analysed by microscopy and metagenetic analysis of the 18S nuclear small subunit ribosomal RNA gene using the 454 pyrosequencing platform. Following quality control a total of 419,041 sequences were obtained for all samples. The sequences clustered into 205 operational taxonomic units using a 97% similarity cut-off. Allocation of taxonomy by comparison with the National Centre for Biotechnology Information database identified 135 OTUs to species level, 11 to genus level and 1 to order, <2.5% of sequences were classified as unknowns. By comparison a skilled microscopic analyst was able to routinely enumerate only 58 taxonomic groups. CONCLUSIONS: Metagenetics reveals a previously hidden taxonomic richness, especially for Copepoda and hard-to-identify meroplankton such as Bivalvia, Gastropoda and Polychaeta. It also reveals rare species and parasites. We conclude that Next Generation Sequencing of 18S amplicons is a powerful tool for elucidating the true diversity and species richness of zooplankton communities. While this approach allows for broad diversity assessments of plankton it may

  20. Models of care and organization of services.

    Science.gov (United States)

    Markova, Alina; Xiong, Michael; Lester, Jenna; Burnside, Nancy J

    2012-01-01

    This article examines the overall organization of services and delivery of health care in the United States. Health maintenance organization, fee-for-service, preferred provider organizations, and the Veterans Health Administration are discussed, with a focus on structure, outcomes, and areas for improvement. An overview of wait times, malpractice, telemedicine, and the growing population of physician extenders in dermatology is also provided. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. 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.

  2. Zooplankton community of Parnaíba River, Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Ludmilla Cavalcanti Antunes Lucena

    2015-03-01

    Full Text Available 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.MethodsZooplankton was collected with a plankton 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.ResultsA 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%.ConclusionsThe 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.

  3. Zooplankton structure in two interconnected ponds: similarities and differences

    Directory of Open Access Journals (Sweden)

    Špoljar Maria

    2016-03-01

    Full Text Available The research of zooplankton diversity, abundance and trophic structure was conducted during the summer period in pelagial zone on the longitudinal profile of the Sutla River Backwater. Investigated site consists of two interconnected basins: transparent Upper Basin with submerged macrophytes and turbid Lower Basin without macrophytes in the littoral zone. In the Upper Basin, abundance and diversity of zooplankton in the pelagial was higher in comparison to the Lower Basin, with prevailing species of genus Keratella as microfilter-feeder, and genera of Polyartha and Trihocerca as macrofilter-feeder rotifers. On the contrary, in the Lower Basin, crustaceans dominated in abundance. Microfilter-feeder cladoceran (Bosmina longirostris and larval and adult stages of macrofilter-feeder copepod (Macrocyclops albidus prevailed in the Lower Basin. Fish predation pressure was more pronounced in the pelagial of the Upper Basin, indicated by low cladoceran abundance in the surface layer. Although the studied basins were interconnected, results indicate significant (Mann-Whitney U test, p < 0.05 differences in the zooplankton structure as a potential result of the macrophyte impact on environmental conditions and fish predation pressure.

  4. Effect of advection on variations in zooplankton at a single location near Cabo Nazca, Peru

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S L; Brink, K H; Santander, H; Cowles, T J; Huyer, A

    1980-04-01

    Temporal variations in the biomass and species composition of zooplankton at a single midshelf station in an upwelling area off Peru can be explained to a large extent by onshore-offshore advection in the upper 20 m of the water column. During periods of strong or sustained near-surface onshore flow, peaks in biomass of zooplankton were observed at midshelf and typically oceanic species of copepod were collected. In periods of offshore flow at the surface, a copepod capable of migrating into oxygen-depleted layers deeper than 30 m was collected. A simple translocation model of advection applied to the cross-shelf distribution of Paracalanus parvus suggests that the fluctuations in P. pavus observed in the midshelf time-series were closely related to onshore-offshore flow in the upper 20 m. Fluctuations in abundance of the numerically dominant copepod, Acartia tonsa, were apparently affected by near surface flow also. The population age-structure suggests that A. tonsa was growing at maximal rates, due in part to its positive feeding response to the dinoflagellate/diatom assemblage of phytoplankton.

  5. Organization model and formalized description of nuclear enterprise information system

    International Nuclear Information System (INIS)

    Yuan Feng; Song Yafeng; Li Xudong

    2012-01-01

    Organization model is one of the most important models of Nuclear Enterprise Information System (NEIS). Scientific and reasonable organization model is the prerequisite that NEIS has robustness and extendibility, and is also the foundation of the integration of heterogeneous system. Firstly, the paper describes the conceptual model of the NEIS on ontology chart, which provides a consistent semantic framework of organization. Then it discusses the relations between the concepts in detail. Finally, it gives the formalized description of the organization model of NEIS based on six-tuple array. (authors)

  6. The characteristic of a zooplankton in the contaminated bottom stream of the Pripyat' river and backwaters

    International Nuclear Information System (INIS)

    Zarubaw, A.I.; Malatkow, D.V.

    1994-01-01

    The researches of zooplankton are conducted on two stations on the Pripyat' river, but also on two backwaters which are in the Chernobyl NPP contamination zone. The rotifera is dominant group of zooplankton. Their quantity is more than 10 samples/litter. An absolute and relative fertility of rotifera is determined. It is established an structural and functional reorganization of the rotifera dominant complexes occurs. Any influence of contamination on a zooplankton condition is not found out. 5 refs., 2 tabs., 2 figs

  7. The lake foodweb: modelling predation and abiotic/biotic interactions

    National Research Council Canada - National Science Library

    Hakanson, L; Boulion, V.V

    2002-01-01

    .... LakeWeb includes the following key functional groups of organisms: phytoplankton, bacterioplankton, benthic algae, macrophytes, zoobenthos, herbivorous and predatory zooplankton, prey fish and predatory fish...

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

    International Nuclear Information System (INIS)

    Yaqoob, N.; Mashiatullah, A.; Sher, N.; Javed, T.; Ghaffar, A.

    2013-01-01

    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)

  9. 3D Bioprinting of Tissue/Organ Models.

    Science.gov (United States)

    Pati, Falguni; Gantelius, Jesper; Svahn, Helene Andersson

    2016-04-04

    In vitro tissue/organ models are useful platforms that can facilitate systematic, repetitive, and quantitative investigations of drugs/chemicals. The primary objective when developing tissue/organ models is to reproduce physiologically relevant functions that typically require complex culture systems. Bioprinting offers exciting prospects for constructing 3D tissue/organ models, as it enables the reproducible, automated production of complex living tissues. Bioprinted tissues/organs may prove useful for screening novel compounds or predicting toxicity, as the spatial and chemical complexity inherent to native tissues/organs can be recreated. In this Review, we highlight the importance of developing 3D in vitro tissue/organ models by 3D bioprinting techniques, characterization of these models for evaluating their resemblance to native tissue, and their application in the prioritization of lead candidates, toxicity testing, and as disease/tumor models. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Nutrient regeneration by zooplankton during a red tide off Peru, with notes on biomass and species composition of zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.L.

    1978-01-01

    During March and April 1976, a red tide, dominated by the dinoflagallate Gymnodinium splendens Lebour, developed in the vicinity of 15/sup 0/O6'S and 76/sup 0/31'W off Peru. At the height of the bloom, the euphotic zone was 6 m deep and the chlorophyll a at the surface was 48 ..mu..g 1/sup -1/. A daily collection of zooplankton at 09.00 hrs showed large fluctuations of biomass, from 0.2 to 3.84 g dry weight m/sup -2/ in a water column of 120 m. Copepodids and nauplii dominated the collections. During a period of reduced wind, the adult copepods were a mixture of the species characteristic of the coastal upwelling system and the neritic species associated with more northerly, tropical waters. Nitrogen regeneration by the zooplankton varied with the development of the bloom, the type of zooplankton dominating the experiment, and biomass fluctuations, but never accounted for more than 25% of the nitrogen uptake by phytoplankton.

  11. Authentication in Virtual Organizations: A Reputation Based PKI Interconnection Model

    Science.gov (United States)

    Wazan, Ahmad Samer; Laborde, Romain; Barrere, Francois; Benzekri, Abdelmalek

    Authentication mechanism constitutes a central part of the virtual organization work. The PKI technology is used to provide the authentication in each organization involved in the virtual organization. Different trust models are proposed to interconnect the different PKIs in order to propagate the trust between them. While the existing trust models contain many drawbacks, we propose a new trust model based on the reputation of PKIs.

  12. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    KAUST Repository

    Kürten, Benjamin

    2015-11-10

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: a) monsoon-related intrusions of nutrient-rich Indian Ocean water; b) basin scale thermohaline circulation; c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and e) the deposition of aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28’ to 26°57’N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of POM in the South

  13. Biomass estimates of freshwater zooplankton from length-carbon regression equations

    Directory of Open Access Journals (Sweden)

    Patrizia COMOLI

    2000-02-01

    Full Text Available We present length/carbon regression equations of zooplankton species collected from Lake Maggiore (N. Italy during 1992. The results are discussed in terms of the environmental factors, e.g. food availability, predation, controlling biomass production of particle- feeders and predators in the pelagic system of lakes. The marked seasonality in the length-standardized carbon content of Daphnia, and its time-specific trend suggest that from spring onward food availability for Daphnia population may be regarded as a simple decay function. Seasonality does not affect the carbon content/unit length of the two predator Cladocera Leptodora kindtii and Bythotrephes longimanus. Predation is probably the most important regulating factor for the seasonal dynamics of their carbon biomass. The existence of a constant factor to convert the diameter of Conochilus colonies into carbon seems reasonable for an organism whose population comes on quickly and just as quickly disappears.

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

    DEFF Research Database (Denmark)

    van Someren Gréve, Hans

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

  15. Regeneration of nitrogen by zooplankton and fish in the Northwest Africa and Peru upwelling ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Whitledge, T E

    1976-01-01

    The availability of nutrients and light are the dominant controlling factors of the levels of primary production in the ocean. In the lower latitudes where most coastal upwelling areas are located, the amount of light is seldom below the critical level to inhibit productivity so nutrients are often the limiting factor in phytoplankton growth. Nutrients utilized in primary productivity are derived from two sources in upwelling areas. Nutrients are introduced to the euphotic zone from depth by the physical processes that create upwelling and nutrients are recycled by biological organisms that inhabit the area. Nitrate introduced into the euphotic zone by upwelling supports new productivity while ammonium and other excretory products regenerated by zooplankton and nekton supports regenerated productivity. Results are reported from studies off the coast of Northwest Africa and Peru using /sup 15/N as a tracer that showed that recycled ammonium may fulfill nearly half of the daily nitrogen requirement of phytoplankton and upwelled nitrate may provide the other half.

  16. Interactive effects of temperature, ultraviolet radiation and food quality on zooplankton alkaline phosphatase activity.

    Science.gov (United States)

    Wolinski, Laura; Modenutti, Beatriz; Souza, Maria Sol; Balseiro, Esteban

    2016-06-01

    Ultraviolet Radiation (UVR) is a stressor for aquatic organisms affecting enzyme activities in planktonic populations because of the increase in reactive oxygen species. In addition, UVR exposure combined with other environmental factors (i.e. temperature and food quality) could have even higher detrimental effects. In this work, we aimed to determine the effect of UVR on somatic Alkaline Phosphatase Activity (APA) and Glutathione S-Transferase (GST) activity on the cladoceran Daphnia commutata under two different temperatures (10 °C and 20 °C) and under three food qualities (carbon:phosphorus ratios: 1150, 850 and 550). APA is a biomarker that is considered as a P deficiency indicator in zooplankton. Since recovery from UVR damage under dark conditions is an ATP depending reaction we also measured APA during recovery phases. We carried out a laboratory experiment combining different temperatures and food qualities with exposition to UVR followed by luminic and dark phases for recovery. In addition, we exposed organisms to H2O2, to establish if the response on APA to UVR was a consequence of the reactive oxygen species produced these short wavelengths. Our results showed that somatic APA was negatively affected by UVR exposure and this effect was enhanced under high temperature and low food quality. Consistently, GST activity was higher when exposed to UVR under both temperatures. The H2O2 experiments showed the same trend as UVR exposure, indicating that APA is affected mainly by oxidative stress than by direct effect of UVR on the enzyme. Finally, APA was affected in the dark phase of recovery confirming the P demands. These results enlighten the importance of food quality in the interacting effect of UVR and temperature, showing that C:P food ratio could determine the success or failure of zooplanktonic populations in a context of global change. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. MODELING OF MANAGEMENT PROCESSES IN AN ORGANIZATION

    Directory of Open Access Journals (Sweden)

    Stefan Iovan

    2016-05-01

    Full Text Available When driving any major change within an organization, strategy and execution are intrinsic to a project’s success. Nevertheless, closing the gap between strategy and execution remains a challenge for many organizations [1]. Companies tend to focus more on execution than strategy for quick results, instead of taking the time needed to understand the parts that make up the whole, so the right execution plan can be put in place to deliver the best outcomes. A large part of this understands that business operations don’t fit neatly within the traditional organizational hierarchy. Business processes are often messy, collaborative efforts that cross teams, departments and systems, making them difficult to manage within a hierarchical structure [2]. Business process management (BPM fills this gap by redefining an organization according to its end-to-end processes, so opportunities for improvement can be identified and processes streamlined for growth, revenue and transformation. This white paper provides guidelines on what to consider when using business process applications to solve your BPM initiatives, and the unique capabilities software systems provides that can help ensure both your project’s success and the success of your organization as a whole. majority of medium and small businesses, big companies and even some guvermental organizations [2].

  18. 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 μg 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

  19. 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...

  20. 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,...

  1. Self-Organizing Map Models of Language Acquisition

    Directory of Open Access Journals (Sweden)

    Ping eLi

    2013-11-01

    Full Text Available Connectionist models have had a profound impact on theories of language. While most early models were inspired by the classic PDP architecture, recent models of language have explored various other types of models, including self-organizing models for language acquisition. In this paper we aim at providing a review of the latter type of models, and highlight a number of simulation experiments that we have conducted based on these models. We show that self-organizing connectionist models can provide significant insights into long-standing debates in both monolingual and bilingual language development.

  2. Different zooplankton structures in the German Bight

    Science.gov (United States)

    Martens, P.; Brockmann, U.

    1993-06-01

    In August 1982, a net of 48 stations with altogether 208 samples was investigated in the eastern German Bight with respect to temperature, salinity, as well as the amount and species composition of the mesozooplankton (>80 μm). The data were arranged into different structures by means of a cluster analysis. Four different clusters were found: (a) a “Wadden sea water” with few holoplankton organisms but a higher amount of spionid larvae; (b) a “German Bight water” with a maximum occurrence of turbellaria ( Alaurina composita) and medium concentrations of copepods; (c) a mixing area between these two water masses with highest amounts of Oikopleura dioica, Temora longicornis, Acartia sp., mussel larvae and larvae of the spionid worms; (d) a “North Sea water” mass with highest concentrations of Pseudocalanus elongatus, Paracalanus parvus und Oithona similis. The differences in the concentrations of the species mentioned between the four clusters were significant on the 0.1%-level.

  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.

    Zooplankton characteristics of the Gulf of Kachchh including the major creek systems of Nakti, Kandla and Hansthal were studied for monsoon, postmonsoon and pre- monsoon periods. Zooplankton collections were made at 7 locations. The area was very...

  4. Secondary production and zooplankton abundance in the coastal waters from Vengurla to Malpe, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    Secondary production and zooplankton abundance in surface and vertical hauls at different stations along 7 transects from Vengurla to Malpe, Maharashtra, India were studied. Zooplankton production varied with the depth of sampling station and type...

  5. The initiative on Model Organism Proteomes (iMOP) Session

    DEFF Research Database (Denmark)

    Schrimpf, Sabine P; Mering, Christian von; Bendixen, Emøke

    2012-01-01

    iMOP – the Initiative on Model Organism Proteomes – was accepted as a new HUPO initiative at the Ninth HUPO meeting in Sydney in 2010. A goal of iMOP is to integrate research groups working on a great diversity of species into a model organism community. At the Tenth HUPO meeting in Geneva...

  6. Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Madronich, Sasha [Univ. Corporation for Atmospheric Research, Boulder, CO (United States)

    2015-12-09

    The atmospheric burden of Secondary Organic Aerosols (SOA) remains one of the most important yet uncertain aspects of the radiative forcing of climate. This grant focused on improving our quantitative understanding of SOA formation and evolution, by developing, applying, and improving a highly detailed model of atmospheric organic chemistry, the Generation of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model. Eleven (11) publications have resulted from this grant.

  7. Mechanisms underlying recovery of zooplankton in Lake Orta after liming

    Directory of Open Access Journals (Sweden)

    Roberta Piscia

    2016-04-01

    Full Text Available The goal of this study was to improve the understanding of the large-scale mechanisms underlying the recovery of the zooplankton of Lake Orta from historical contamination, following reduced input of ammonia and metals and the subsequent 1989/90 liming intervention. The industrial pollution had been severe and long-lasting (1929-1990. Zooplankton biodiversity has improved, but most of the new taxa appearing in our counts are rotifers, while many calanoids and the large cladoceran predators (Bythotrephes and Leptodora that are common in the nearby Lake Maggiore, were still absent from Lake Orta 17 years after liming. To aid understanding of the large-scale mechanisms controlling changes in annual richness, we assessed the annual persistence (P of Crustacea and Rotifera taxa as an estimator of whether propagules that survived introduction, as result of the natural recolonization process, also thrived. We found that the rate of introduction of zooplankton colonists and their persistence in the water column of Lake Orta changed from 1971 to 2007. New rotifer taxa appeared in the lake after the mid-1980s, when discharge of toxic substances decreased, but their annual persistence was low (P<0.5 until the turn of the century. The numerical values of rotifer and crustacean persistence in Lake Orta were unexpectedly high in 2001 and 2007 (0.55 and 0.72 for rotifers, 0.85 and 0.86 for crustacean, respectively, much higher than in limed lakes in Sudbury, Canada, and in adjacent Lake Maggiore. We hypothesize this could be related to the lack of Cladoceran predators and zooplanktivorous fish in the pelagic waters of Lake Orta.

  8. Temporal and spatial variability of zooplankton on the Faroe shelf in spring 1997-2016

    Science.gov (United States)

    Jacobsen, Sólvá; Gaard, Eilif; Larsen, Karin Margretha Húsgarð; Eliasen, Sólvá Káradóttir; Hátún, Hjálmar

    2018-01-01

    Zooplankton availability during spring and summer determines the growth and survival of first-feeding fish larvae, and thus impacts the recruitment to both fish prey species and commercial fish stocks. On the Faroe shelf, however, the relative importance of oceanic versus neritic zooplankton species has hitherto not been well understood. In this study, spatio-temporal variability in zooplankton community structure and size spectra on the Faroe shelf is investigated using observations from late April during the period 1997-2016. The main objective was to explore which environmental variables influence the zooplankton community structure in early spring. The zooplankton community in the permanently well mixed central shelf inside the tidal front consists of a mixture of neritic, cosmopolitan and oceanic species. In this region, redundancy analyses showed that chlorophyll concentration had a positive effect on abundance of neritic copepods and meroplankton as well as all zooplankton abundance variability of these species shows increased production around 2000 and 2008-2009. The highest zooplankton abundance, mainly consisting of Calanus finmarchicus, is however observed off-shore from the tidal front, especially on the western side of the Faroe Plateau. A shift in C. finmarchicus phenology occurred around 2007, resulting in earlier reproduction of this species, and this variability could not be explained by the employed regional environmental parameters. Our results indicate that the Faroe shelf biological production is more dependent on the local primary production and neritic zooplankton species than on the large oceanic C. finmarchicus stock.

  9. Biomass and composition of zooplankton in the nearshore waters of Thal, Maharashtra

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Gajbhiye, S.N; Krishnakumari, L; Desai, B.N

    Biomass and composition of zooplankton in the nearshore waters of Thal, Maharashtra, India were studied at 9 stations during Feb. 1980 to Jan. 1981. The recorded variation in zooplankton biomass was 4.8-80.6 ml.(100 m super(3))/1 [av. 22.9 ml.(100 m...

  10. Biomass and composition of zooplankton in Auranga, Ambika, Purna and Mindola estuaries of south Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Gajbhiye, S.N.; JiyalalRam, M.J.; Desai, B.N.

    Biomass and composition of zooplankton in the nearshore waters of Thal, Maharashtra, India were studied at 9 stations during Feb. 1980 to Jan. 1981. The recorded variation in zooplankton biomass was 4.8-80.6 ml.(100 m super(3))/1 [av. 22.9 ml.(100 m...

  11. Biomass and composition of zooplankton in and around Gulf of Kutch

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.; Kasinathan, R.; Desai, B.N.

    Biomass and composition of zooplankton in the nearshore waters of Thal, Maharashtra, India were studied at 9 stations during Feb. 1980 to Jan. 1981. The recorded variation in zooplankton biomass was 4.8-80.6 ml.(100 m super(3))/1 [av. 22.9 ml.(100 m...

  12. 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...

  13. Distribution of toxic metals, Hg, Cd and Pb in zooplankton along the Indian coasts

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, R.; Kureishy, T.W.

    Distribution of toxic metals such as Hg, Cd and Pb in zooplankton is assessed with a view to correlate it with the prevalent environmental conditions along the Indian coast. While Hg could not be detected in zooplankton the concentrations of Cd...

  14. Zooplankton standing stock and composition in coastal waters of Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    Temporal and spatial variability in standing stock and zooplankton composition at 5 stations along the Goa Coast, India during 1975-76 were studied. Standing stock values ranged from 22.81 to 53.65 mg C.m/3. Zooplankton community was diverse...

  15. 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...

  16. Saccharomyces cerevisiae as a model organism: a comparative study.

    Directory of Open Access Journals (Sweden)

    Hiren Karathia

    Full Text Available BACKGROUND: Model organisms are used for research because they provide a framework on which to develop and optimize methods that facilitate and standardize analysis. Such organisms should be representative of the living beings for which they are to serve as proxy. However, in practice, a model organism is often selected ad hoc, and without considering its representativeness, because a systematic and rational method to include this consideration in the selection process is still lacking. METHODOLOGY/PRINCIPAL FINDINGS: In this work we propose such a method and apply it in a pilot study of strengths and limitations of Saccharomyces cerevisiae as a model organism. The method relies on the functional classification of proteins into different biological pathways and processes and on full proteome comparisons between the putative model organism and other organisms for which we would like to extrapolate results. Here we compare S. cerevisiae to 704 other organisms from various phyla. For each organism, our results identify the pathways and processes for which S. cerevisiae is predicted to be a good model to extrapolate from. We find that animals in general and Homo sapiens in particular are some of the non-fungal organisms for which S. cerevisiae is likely to be a good model in which to study a significant fraction of common biological processes. We validate our approach by correctly predicting which organisms are phenotypically more distant from S. cerevisiae with respect to several different biological processes. CONCLUSIONS/SIGNIFICANCE: The method we propose could be used to choose appropriate substitute model organisms for the study of biological processes in other species that are harder to study. For example, one could identify appropriate models to study either pathologies in humans or specific biological processes in species with a long development time, such as plants.

  17. The System Dynamics Model for Development of Organic Agriculture

    Science.gov (United States)

    Rozman, Črtomir; Škraba, Andrej; Kljajić, Miroljub; Pažek, Karmen; Bavec, Martina; Bavec, Franci

    2008-10-01

    Organic agriculture is the highest environmentally valuable agricultural system, and has strategic importance at national level that goes beyond the interests of agricultural sector. In this paper we address development of organic farming simulation model based on a system dynamics methodology (SD). The system incorporates relevant variables, which affect the development of the organic farming. The group decision support system (GDSS) was used in order to identify most relevant variables for construction of causal loop diagram and further model development. The model seeks answers to strategic questions related to the level of organically utilized area, levels of production and crop selection in a long term dynamic context and will be used for simulation of different policy scenarios for organic farming and their impact on economic and environmental parameters of organic production at an aggregate level.

  18. Fine-Scale Distributions of Zooplankton in the Northern San Francisco Estuary

    Directory of Open Access Journals (Sweden)

    Wim Kimmerer

    2016-10-01

    Full Text Available doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art2 We studied zooplankton distributions in the upper San Francisco Estuary at nested scales of tens to thousands of meters. The purposes of the study were to assess how well the Interagency Ecological Program (IEP zooplankton monitoring represents abundance, and to investigate the variability of plankton on scales similar to those of foraging by fish. Samples were taken at three sites in the western Sacramento–San Joaquin Delta. We took 18 sets of six samples each with a plankton net along transects from near shore to center channel, and six sets of ten samples in the vicinity of a drifter either in mid-channel or near shore. Sampling took place in June–July 2014 during neap and spring tides, ebb and flood, day and night (transects only. Analysis focused on three common copepod species. Transect samples showed little consistent variation along transects, except that Pseudodiaptomus forbesi was less abundant nearshore than offshore by day at Big Break, the most landward site. The ratio of adults to adults + copepodites was strongly and positively related to turbidity by day but not by night, indicating demersal behavior. Drifter samples showed a minimum standard deviation of log10 sample counts of about 0.1, indicating that about two-thirds of replicate abundance values were within 80 % to 125% of the mean. A measure of difference between plankton samples at pairs of sample points was unrelated to distance between sample points for drifter samples, weakly related along transects for Limnoithona spp. stages, and strongly related for P. forbesi mainly because of the along-transect gradients at Big Break. The IEP sampling program is representative of plankton abundance except for demersal organisms, which can be ten-fold more abundant by night than by day. Small planktivorous fish could forage in patches of up to ~25% higher abundance than the mean.

  19. 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.

  20. A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon.

    Science.gov (United States)

    Kipka, Undine; Di Toro, Dominic M

    2011-09-01

    Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (K(DOC)) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating K(DOC) to the octanol-water partition coefficient (K(OW)) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse K(DOC) data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log K(DOC) with a root mean square error of 0.43. Copyright © 2011 SETAC.

  1. Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part I: Effects of Bisphenol A on Freshwater Zooplankton Are Lower in Presence of Polyamide Particles

    Science.gov (United States)

    Rehse, Saskia; Kloas, Werner; Zarfl, Christiane

    2018-01-01

    Microplastics can have direct physical effects on organisms in freshwater systems, and are considered as vectors for absorbed environmental pollutants. It is still under discussion if microplastics are relevant pollutant vectors for uptake into aquatic organisms in comparison to further uptake pathways, e.g., via water or sediment particles. We analyzed how the presence of microplastics (polyamide particles, PA) modifies acute effects of the environmental pollutant bisphenol A (BPA) on freshwater zooplankton (Daphnia magna). Daphnids were exposed to PA particles and BPA alone, before combining them in the next step with one concentration of PA and varying concentrations of BPA. The PA particles themselves did not induce negative effects, while the effects of BPA alone followed a typical dose-dependent manner. Sorption of BPA to PA particles prior to exposure led to a reduction of BPA in the aqueous phase. The combination of BPA and PA led to decreased immobilization, although PA particles loaded with BPA were ingested by the daphnids. Calculations based on physiochemistry and equilibrium assumptions indicated lower BPA body burden of daphnids in the presence of PA particles. These results confirm model-based studies, and show that investigated microplastic concentrations are negligible for the overall pollutant uptake of daphnids with water as additional uptake pathway. PMID:29415519

  2. Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part I: Effects of Bisphenol A on Freshwater Zooplankton Are Lower in Presence of Polyamide Particles

    Directory of Open Access Journals (Sweden)

    Saskia Rehse

    2018-02-01

    Full Text Available Microplastics can have direct physical effects on organisms in freshwater systems, and are considered as vectors for absorbed environmental pollutants. It is still under discussion if microplastics are relevant pollutant vectors for uptake into aquatic organisms in comparison to further uptake pathways, e.g., via water or sediment particles. We analyzed how the presence of microplastics (polyamide particles, PA modifies acute effects of the environmental pollutant bisphenol A (BPA on freshwater zooplankton (Daphnia magna. Daphnids were exposed to PA particles and BPA alone, before combining them in the next step with one concentration of PA and varying concentrations of BPA. The PA particles themselves did not induce negative effects, while the effects of BPA alone followed a typical dose-dependent manner. Sorption of BPA to PA particles prior to exposure led to a reduction of BPA in the aqueous phase. The combination of BPA and PA led to decreased immobilization, although PA particles loaded with BPA were ingested by the daphnids. Calculations based on physiochemistry and equilibrium assumptions indicated lower BPA body burden of daphnids in the presence of PA particles. These results confirm model-based studies, and show that investigated microplastic concentrations are negligible for the overall pollutant uptake of daphnids with water as additional uptake pathway.

  3. Zooplankton size selection relative to gill raker spacing in rainbow trout

    Science.gov (United States)

    Budy, P.; Haddix, T.; Schneidervin, R.

    2005-01-01

    Rainbow trout Oncorhynchus mykiss are one of the most widely stocked salmonids worldwide, often based on the assumption that they will effectively utilize abundant invertebrate food resources. We evaluated the potential for feeding morphology to affect prey selection by rainbow trout using a combination of laboratory feeding experiments and field observations in Flaming Gorge Reservoir, Utah-Wyoming. For rainbow trout collected from the reservoir, inter-gill raker spacing averaged 1.09 mm and there was low variation among fish overall (SD = 0.28). Ninety-seven percent of all zooplankton observed in the diets of rainbow trout collected in the reservoir were larger than the interraker spacing, while only 29% of the zooplankton found in the environment were larger than the interraker spacing. Over the size range of rainbow trout evaluated here (200-475 mm), interraker spacing increased moderately with increasing fish length; however, the size of zooplankton found in the diet did not increase with increasing fish length. In laboratory experiments, rainbow trout consumed the largest zooplankton available; the mean size of zooplankton observed in the diets was significantly larger than the mean size of zooplankton available. Electivity indices for both laboratory and field observations indicated strong selection for larger-sized zooplankton. The size threshold at which electivity switched from selection against smaller-sized zooplankton to selection for larger-sized zooplankton closely corresponded to the mean interraker spacing for both groups (???1-1.2 mm). The combination of results observed here indicates that rainbow trout morphology limits the retention of different-sized zooplankton prey and reinforces the importance of understanding how effectively rainbow trout can utilize the type and sizes of different prey available in a given system. These considerations may improve our ability to predict the potential for growth and survival of rainbow trout within and

  4. Zooplankton community response to experimental acidification in boreal shield lakes with different ecological histories

    Energy Technology Data Exchange (ETDEWEB)

    Derry, A.M.; Arnott, S.E. [Queen' s Univ., Kingston, ON (Canada). Dept. of Biology

    2007-06-15

    This study investigated the adaptive response of crustacean zooplankton to widespread regional acidification at the Killarney Provincial Park in Ontario. Mesocosm experiments were conducted in 2 circumneutral lakes with different acidification histories. A reciprocal transplant field enclosure experiment was conducted to assess whether the zooplankton community within the acid-recovering boreal shield lake showed evidence of increased acid tolerance to historical acidification following a 6 year period in which the lake's pH was 6.0. The enclosures were filled with epilimnetic water from the lake. Zooplankton from other lakes in the area were used. Zooplankton and water samples were collected from the enclosures once a week. Shannon-Wiener indices, species richness, and total abundance of the zooplankton were calculated for each sample day. Repeated measures analyses of variance (RM-ANOVAs) were used to test for the effects of the incubation lake, the zooplankton source, and the pH. Species abundance data were log{sub 10} transformed to improve homogeneity of variances and normality. Principle components analysis was conducted on species abundances to infer the influence of treatments on zooplankton community composition. Zooplankton were also transferred from 1 lake to the other in order to determine if subtle differences in local water chemistry and food conditions were limiting the recovery of species in acid-recovering lakes. The study showed that 2 key species, H. gibberum and L. minutus, contributed to community-level differences to acid tolerance of zooplankton with different acidification histories. It was concluded that zooplankton with adaptable acid tolerances may monopolize resources in acidified and acid-recovering lakes, and may contribute to the delayed recolonization of other taxa. 62 refs., 3 tabs., 6 figs.

  5. Modeling the influence of organic acids on soil weathering

    Science.gov (United States)

    Lawrence, Corey R.; Harden, Jennifer W.; Maher, Kate

    2014-01-01

    Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

  6. Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems.

    Science.gov (United States)

    Vasseur, David A; Fox, Jeremy W; Gonzalez, Andrew; Adrian, Rita; Beisner, Beatrix E; Helmus, Matthew R; Johnson, Catherine; Kratina, Pavel; Kremer, Colin; de Mazancourt, Claire; Miller, Elizabeth; Nelson, William A; Paterson, Michael; Rusak, James A; Shurin, Jonathan B; Steiner, Christopher F

    2014-08-07

    Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  7. Daphnia as an Emerging Epigenetic Model Organism

    Directory of Open Access Journals (Sweden)

    Kami D. M. Harris

    2012-01-01

    Full Text Available Daphnia offer a variety of benefits for the study of epigenetics. Daphnia’s parthenogenetic life cycle allows the study of epigenetic effects in the absence of confounding genetic differences. Sex determination and sexual reproduction are epigenetically determined as are several other well-studied alternate phenotypes that arise in response to environmental stressors. Additionally, there is a large body of ecological literature available, recently complemented by the genome sequence of one species and transgenic technology. DNA methylation has been shown to be altered in response to toxicants and heavy metals, although investigation of other epigenetic mechanisms is only beginning. More thorough studies on DNA methylation as well as investigation of histone modifications and RNAi in sex determination and predator-induced defenses using this ecologically and evolutionarily important organism will contribute to our understanding of epigenetics.

  8. Nematodes: Model Organisms in High School Biology

    Science.gov (United States)

    Bliss, TJ; Anderson, Margery; Dillman, Adler; Yourick, Debra; Jett, Marti; Adams, Byron J.; Russell, RevaBeth

    2007-01-01

    In a collaborative effort between university researchers and high school science teachers, an inquiry-based laboratory module was designed using two species of insecticidal nematodes to help students apply scientific inquiry and elements of thoughtful experimental design. The learning experience and model are described in this article. (Contains 4…

  9. Effects of wind forcing on the trophic conditions, zooplankton biomass and krill biochemical composition in the Gulf of Tehuantepec

    Science.gov (United States)

    Färber-Lorda, Jaime; Lavín, M. F.; Guerrero-Ruiz, M. A.

    2004-03-01

    The trophic conditions, the zooplankton biomass and the krill biochemical composition in the Gulf of Tehuantepec were studied in relation to spatial and temporal changes in the physical environment, caused by Norte winds. These winds, which occur mostly from October to March, are intermittent, strong wind jets that blow offshore and normal to the coast at the head of the Gulf of Tehuantepec. Ekman pumping raises the thermocline in the east and lowers it in the west of the jet axis; in the central region of the gulf, vertical mixing brings cool, nutrient-rich waters to the surface, enhancing biological productivity. Data from a January 1989 survey show that mean zooplankton biomass was highest in the central region, but there was no significant difference between the three regions (east, central and west). Among euphausiids, Euphausia lamelligera was the dominant species, with 92%. Mean particulate protein, lipids and particulate organic matter (POM = protein + carbohydrates + lipids) did not show significant differences among the three regions; however, mean particulate carbohydrates were significantly different. For the entire area, low but significant linear regressions between (ArcSin) lipids in euphausiids and lipids in POM, and between POM and (ArcSin) lipids in euphausiids were obtained. Better regressions between zooplankton biomass and POM and other variables were obtained when stations were analyzed by hydrographic regions. When data were grouped into those taken before and after a strong Norte (Leg I and Leg II, respectively), a significant positive regression was obtained between (ArcSin) krill lipids and POM for Leg I; but for Leg II, the slope, although not statistically significant, was negative. POM is apparently utilized during Leg II, but the response in the lipid content of the animals is evident only after some time has passed (during Leg I), when the animals had assimilated the food surplus.

  10. The zooplankton biodiversity of some freshwater environments in Parnaíba basin (Piauí, Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    JDN. Paranhos

    Full Text Available The plankton fauna of the state of Piauí, Northeastern Brazil, especially in the Parnaíba basin, is still poorly known; the results of most studies of the subject have not been published and can only be found in grey literature (unpublished scientific works, such as course completion work and consulting reports. Thus, this paper presents data from samples taken recently from different water bodies in Piauí and represents the second study to be published on the region's zooplankton since the pioneering work of Spandl (1926. A total of 38 species were recorded, including 23 new occurrences of rotifers, 10 of cladocerans and 2 of copepods for the state of Piauí. The greatest richness was observed for the rotifers, of which the genus Brachionus must be highlighted, especially at the Joana reservoir. Among the crustaceans, the greatest richness was observed at the Bezerra reservoir, where cladocerans of the genus Bosmina were prominent. The rotifers Brachionus havanaensis Rousselet, 1911 and Filinia longiseta (Ehrenberg, 1834; the cladocerans Diaphanosoma spinulosum Herbst, 1967 and Moina micrura Kurz, 1874; and the copepods Notodiaptomus cearensis Wright, 1936 and Thermocyclops decipiens Kiefer, 1927 occurred in all or in most environments in which the respective groups were studied. The results presented here expand the taxonomic list of zooplankton for the state of Piauí, including a total fauna of 30 species of rotifers, 15 of cladocerans and 3 of copepods. The zooplankton richness was considered low in the studied reservoirs compared to other freshwater ecosystems from Northeastern Brazil; however, the few studies developed in the Parnaíba basin suggest that the diversity for these organisms should be higher.

  11. Amino acid composition reveals functional diversity of zooplankton in tropical lakes related to geography, taxonomy and productivity.

    Science.gov (United States)

    Aranguren-Riaño, Nelson J; Guisande, Cástor; Shurin, Jonathan B; Jones, Natalie T; Barreiro, Aldo; Duque, Santiago R

    2018-04-16

    Variation in resource use among species determines their potential for competition and co-existence, as well as their impact on ecosystem processes. Planktonic crustaceans consume a range of micro-organisms that vary among habitats and species, but these differences in resource consumption are difficult to characterize due to the small size of the organisms. Consumers acquire amino acids from their diet, and the composition of tissues reflects both the use of different resources and their assimilation in proteins. We examined the amino acid composition of common crustacean zooplankton from 14 tropical lakes in Colombia in three regions (the Amazon floodplain, the eastern range of the Andes, and the Caribbean coast). Amino acid composition varied significantly among taxonomic groups and the three regions. Functional richness in amino acid space was greatest in the Amazon, the most productive region, and tended to be positively related to lake trophic status, suggesting the niche breadth of the community could increase with ecosystem productivity. Functional evenness increased with lake trophic status, indicating that species were more regularly distributed within community-wide niche space in more productive lakes. These results show that zooplankton resource use in tropical lakes varies with both habitat and taxonomy, and that lake productivity may affect community functional diversity and the distribution of species within niche space.

  12. Self-organized quantum rings : Physical characterization and theoretical modeling

    NARCIS (Netherlands)

    Fomin, V.M.; Gladilin, V.N.; Devreese, J.T.; Koenraad, P.M.; Fomin, V.M.

    2014-01-01

    An adequate modeling of the self-organized quantum rings is possible only on the basis of the modern characterization of those nanostructures.We discuss an atomic-scale analysis of the indium distribution of self-organized InGaAs quantum rings (QRs). The analysis of the shape, size and composition

  13. Resilient organizations: matrix model and service line management.

    Science.gov (United States)

    Westphal, Judith A

    2005-09-01

    Resilient organizations modify structures to meet the demands of the marketplace. The author describes a structure that enables multihospital organizations to innovate and rapidly adapt to changes. Service line management within a matrix model is an evolving organizational structure for complex systems in which nurses are pivotal members.

  14. (Tropical) soil organic matter modelling: problems and prospects

    NARCIS (Netherlands)

    Keulen, van H.

    2001-01-01

    Soil organic matter plays an important role in many physical, chemical and biological processes. However, the quantitative relations between the mineral and organic components of the soil and the relations with the vegetation are poorly understood. In such situations, the use of models is an

  15. Investigating ecological speciation in non-model organisms

    DEFF Research Database (Denmark)

    Foote, Andrew David

    2012-01-01

    Background: Studies of ecological speciation tend to focus on a few model biological systems. In contrast, few studies on non-model organisms have been able to infer ecological speciation as the underlying mechanism of evolutionary divergence. Questions: What are the pitfalls in studying ecological...... speciation in non-model organisms that lead to this bias? What alternative approaches might redress the balance? Organism: Genetically differentiated types of the killer whale (Orcinus orca) exhibiting differences in prey preference, habitat use, morphology, and behaviour. Methods: Review of the literature...... on killer whale evolutionary ecology in search of any difficulty in demonstrating causal links between variation in phenotype, ecology, and reproductive isolation in this non-model organism. Results: At present, we do not have enough evidence to conclude that adaptive phenotype traits linked to ecological...

  16. Modelling the self-organization and collapse of complex networks

    Indian Academy of Sciences (India)

    Modelling the self-organization and collapse of complex networks. Sanjay Jain Department of Physics and Astrophysics, University of Delhi Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore Santa Fe Institute, Santa Fe, New Mexico.

  17. Self-organizing map models of language acquisition

    Science.gov (United States)

    Li, Ping; Zhao, Xiaowei

    2013-01-01

    Connectionist models have had a profound impact on theories of language. While most early models were inspired by the classic parallel distributed processing architecture, recent models of language have explored various other types of models, including self-organizing models for language acquisition. In this paper, we aim at providing a review of the latter type of models, and highlight a number of simulation experiments that we have conducted based on these models. We show that self-organizing connectionist models can provide significant insights into long-standing debates in both monolingual and bilingual language development. We suggest future directions in which these models can be extended, to better connect with behavioral and neural data, and to make clear predictions in testing relevant psycholinguistic theories. PMID:24312061

  18. Labour Quality Model for Organic Farming Food Chains

    OpenAIRE

    Gassner, B.; Freyer, B.; Leitner, H.

    2008-01-01

    The debate on labour quality in science is controversial as well as in the organic agriculture community. Therefore, we reviewed literature on different labour quality models and definitions, and had key informant interviews on labour quality issues with stakeholders in a regional oriented organic agriculture bread food chain. We developed a labour quality model with nine quality categories and discussed linkages to labour satisfaction, ethical values and IFOAM principles.

  19. Xanthusbase: adapting wikipedia principles to a model organism database

    OpenAIRE

    Arshinoff, Bradley I.; Suen, Garret; Just, Eric M.; Merchant, Sohel M.; Kibbe, Warren A.; Chisholm, Rex L.; Welch, Roy D.

    2006-01-01

    xanthusBase () is the official model organism database (MOD) for the social bacterium Myxococcus xanthus. In many respects, M.xanthus represents the pioneer model organism (MO) for studying the genetic, biochemical, and mechanistic basis of prokaryotic multicellularity, a topic that has garnered considerable attention due to the significance of biofilms in both basic and applied microbiology research. To facilitate its utility, the design of xanthusBase incorporates open-source software, leve...

  20. Effects of increased zooplankton biomass on phytoplankton and cyanotoxins: A tropical mesocosm study.

    Science.gov (United States)

    Dos Santos Severiano, Juliana; Dos Santos Almeida-Melo, Viviane Lúcia; Bittencourt-Oliveira, Maria do Carmo; Chia, Mathias Ahii; do Nascimento Moura, Ariadne

    2018-01-01

    Zooplankton are important biocontrol agents for algal blooms in temperate lakes, while their potential in tropical and subtropical environments is not well understood. The aim of the present study was to evaluate the influence of increased zooplankton biomass on phytoplankton community and cyanotoxins (microcystins and saxitoxin) content of a tropical reservoir (Ipojuca reservoir, Brazil) using in situ mesocosms. Mesocosms consisted of 50L transparent polyethylene bags suspended in the reservoir for twelve days. Phytoplankton populations were exposed to treatments having 1 (control), 2, 3 and 4 times the biomass of zooplankton found in the reservoir at the beginning of the experiment. Filamentous cyanobacteria such as Planktothrix agardhii and Cylindrospermopsis raciborskii were not negatively influenced by increasing zooplankton biomass. In contrast, the treatments with 3 and 4 times zooplankton biomass negatively affected the cyanobacteria Aphanocapsa sp., Chroococcus sp., Dolichospermum sp., Merismopedia tenuissima, Microcystis aeruginosa and Pseudanabaena sp.; the diatom Cyclotella meneghiniana; and the cryptophyte Cryptomonas sp. Total microcystin concentration both increased and decreased at different times depending on zooplankton treatment, while saxitoxin level was not significantly different between the treatments and control. The results of the present study suggest that zooplankton biomass can be manipulated to control the excessive proliferation of non-filamentous bloom forming cyanobacteria (e.g. M. aeruginosa) and their associated cyanotoxins. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Zooplankton responses to sandbar opening in a tropical eutrophic coastal lagoon

    Science.gov (United States)

    Santangelo, Jayme M.; de M. Rocha, Adriana; Bozelli, Reinaldo L.; Carneiro, Luciana S.; de A. Esteves, Francisco

    2007-02-01

    The effects of a disturbance by sandbar opening on the zooplankton community were evaluated through a long-term study in an eutrophic and oligohaline system, Imboassica Lagoon, Rio de Janeiro, Brazil. Zooplankton samples and limnological data were collected monthly from March 2000 to February 2003. Before the sandbar was opened in February 2001, the lagoon showed eutrophic conditions, with high mean nutrient concentrations and low salinity (total nitrogen - TN = 190.28 μM, chlorophyll a content - Chl. a = 104.60 μg/L and salinity = 0.87'). During this period, the zooplankton species present, such as the rotifers Brachionus calyciflorus and Brachionus havanaensis, were typical of freshwater to oligohaline and eutrophic environments. After the sandbar opening, the lagoon changed to a lower trophic status and increased salinity (TN = 55.11 μM, Chl. a = 27.56 μg/L and salinity = 19.64'). As a result, the zooplankton community came to consist largely of the rotifer Brachionus plicatilis, marine copepods and meroplanktonic larvae, mainly Gastropoda. Salinity was the main force structuring the zooplankton community after the sandbar opening. Two years after this episode, the prior zooplankton community had not reestablished itself, indicating a low resilience to this disturbance. The conditions developed prior to a sandbar opening can be crucial to the community responses in the face of this disturbance and for the capacity of the original zooplankton community to re-establish itself.

  2. Zooplankton structure and vertical migration: Using acoustics and biomass to compare stratified and mixed fjord systems

    Science.gov (United States)

    Díaz-Astudillo, Macarena; Cáceres, Mario A.; Landaeta, Mauricio F.

    2017-09-01

    The patterns of abundance, composition, biomass and vertical migration of zooplankton in short-time scales (ADCP device mounted on the hull of a ship were used to obtain vertical profiles of current velocity data and intensity of the backscattered acoustic signal, which was used to study the migratory strategies and to relate the echo intensity with zooplankton biomass. Repeated vertical profiles of temperature, salinity and density were obtained with a CTD instrument to describe the density patterns during both experiments. Zooplankton were sampled every 3 h using a Bongo net to determine abundance, composition and biomass. Migrations were diel in the stratified station, semi-diel in the mixed station, and controlled by light in both locations, with large and significant differences in zooplankton abundance and biomass between day and night samples. No migration pattern associated with the effect of tides was found. The depth of maximum backscatter strength showed differences of approximately 30 m between stations and was deeper in the mixed station. The relation between mean volume backscattering strength (dB) computed from echo intensity and log10 of total dry weight (mg m-3) of zooplankton biomass was moderate but significant in both locations. Biomass estimated from biological samples was higher in the mixed station and determined by euphausiids. Copepods were the most abundant group in both stations. Acoustic methods were a useful technique to understand the detailed patterns of migratory strategies of zooplankton and to help estimate zooplankton biomass and abundance in the inner waters of southern Chile.

  3. 137Cs concentration in zooplankton and its relation to taxonomic composition in the western North Pacific Ocean

    International Nuclear Information System (INIS)

    Kaeriyama, Hideki; Watabe, Teruhisa; Kusakabe, Masashi

    2008-01-01

    To study the role of zooplankton in the transport of 137 Cs in the ocean, zooplankton samples were collected in October 2005 and June 2006 in the western North Pacific Ocean. The peak zooplankton biomass was observed in the surface layer, and gelatinous plankton was more abundant in October 2005 than in June 2006 reflecting exchange of water masses. The concentrations of 137 Cs in zooplankton varied from 11 to 24 mBq kg wet -1 and were higher in October 2005 than in June 2006. The elevated abundance of gelatinous zooplankton probably led to higher concentration of 137 Cs in zooplankton in October 2005. Annual export fluxes of 137 Cs by ontogenetic vertical migrant copepods were estimated to be 0.8 and 0.6 mBq m -2 year -1 at 200 and 1000 m depths, respectively; this suggested that transport of 137 Cs by zooplankton may be no trivial pathway

  4. Knowledge Loss: A Defensive Model In Nuclear Research Organization Memory

    International Nuclear Information System (INIS)

    Mohamad Safuan Bin Sulaiman; Muhd Noor Muhd Yunus

    2013-01-01

    Knowledge is an essential part of research based organization. It should be properly managed to ensure that any pitfalls of knowledge retention due to knowledge loss of both tacit and explicit is mitigated. Audit of the knowledge entities exist in the organization is important to identify the size of critical knowledge. It is very much related to how much know-what, know-how and know-why experts exist in the organization. This study conceptually proposed a defensive model for Nuclear Malaysia's organization memory and application of Knowledge Loss Risk Assessment (KLRA) as an important tool for critical knowledge identification. (author)

  5. NEW MODEL FOR QUANTIFICATION OF ICT DEPENDABLE ORGANIZATIONS RESILIENCE

    Directory of Open Access Journals (Sweden)

    Zora Arsovski

    2011-03-01

    Full Text Available Business environment today demands high reliable organizations in every segment to be competitive on the global market. Beside that, ICT sector is becoming irreplaceable in many fields of business, from the communication to the complex systems for process control and production. To fulfill those requirements and to develop further, many organizations worldwide are implementing business paradigm called - organizations resilience. Although resilience is well known term in many science fields, it is not well studied due to its complex nature. This paper is dealing with developing the new model for assessment and quantification of ICT dependable organizations resilience.

  6. From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part I zooplankton and micronekton

    Science.gov (United States)

    Denda, Anneke; Stefanowitsch, Benjamin; Christiansen, Bernd

    2017-12-01

    Specific mechanisms, driving trophic interactions within the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure of zooplankton and micronekton above and around Ampère and Senghor, two shallow seamounts in the subtropical and tropical Eastern Atlantic, and over the adjacent abyssal plains. For the identification of food sources and trophic positions stable isotope ratios (δ13C and δ15N) were used. δ13C ranged from -24.7‰ to -15.0‰ and δ15N covered a total range of 0.9-15.9‰. Based on epipelagic particulate organic matter, zooplankton and micronekton usually occupied the 1st-3rd trophic level, including herbivorous, omnivorous and carnivorous taxa. δ13C and δ15N values were generally lower in zooplankton and micronekton of the subtropical waters as compared to the tropical region, due to the differing nutrient availability and phytoplankton communities. Correlations between δ13C and δ15N values of particulate organic matter, zooplankton, micronekton and benthopelagic fishes suggest a linear food chain based on a single energy source from primary production for Ampère Seamount, but no evidence was found for an autochthonus seamount production as compared to the open ocean reference site. Between Senghor Seamount and the open ocean δ13C signatures indicate that hydrodynamic effects at seamounts may modify the energy supply at times, but evidence for a seamount effect on the trophic structure of the pelagic communities was weak, which supports the assumption that seamount communities rely to a large extent on advected food sources.

  7. A model to accumulate fractionated dose in a deforming organ

    International Nuclear Information System (INIS)

    Yan Di; Jaffray, D.A.; Wong, J.W.

    1999-01-01

    Purpose: Measurements of internal organ motion have demonstrated that daily organ deformation exists throughout the course of radiation treatment. However, a method of constructing the resultant dose delivered to the organ volume remains a difficult challenge. In this study, a model to quantify internal organ motion and a method to construct a cumulative dose in a deforming organ are introduced. Methods and Materials: A biomechanical model of an elastic body is used to quantify patient organ motion in the process of radiation therapy. Intertreatment displacements of volume elements in an organ of interest is calculated by applying an finite element method with boundary conditions, obtained from multiple daily computed tomography (CT) measurements. Therefore, by incorporating also the measurements of daily setup error, daily dose delivered to a deforming organ can be accumulated by tracking the position of volume elements in the organ. Furthermore, distribution of patient-specific organ motion is also predicted during the early phase of treatment delivery using the daily measurements, and the cumulative dose distribution in the organ can then be estimated. This dose distribution will be updated whenever a new measurement becomes available, and used to reoptimize the ongoing treatment. Results: An integrated process to accumulate dosage in a daily deforming organ was implemented. In this process, intertreatment organ motion and setup error were systematically quantified, and incorporated in the calculation of the cumulative dose. An example of the rectal wall motion in a prostate treatment was applied to test the model. The displacements of volume elements in the rectal wall, as well as the resultant doses, were calculated. Conclusion: This study is intended to provide a systematic framework to incorporate daily patient-specific organ motion and setup error in the reconstruction of the cumulative dose distribution in an organ of interest. The realistic dose

  8. Metabarcoding Reveals Seasonal and Temperature-Dependent Succession of Zooplankton Communities in the Red Sea

    KAUST Repository

    Casas, Laura; Pearman, John K.; Irigoien, Xabier

    2017-01-01

    Very little is known about the composition and the annual cycle of zooplankton assemblages in the Red Sea, a confined water body characterized by a high biodiversity and endemism but at the same time one of the most understudied areas in the world in terms of marine biodiversity. This high diversity together with the lack of references for several of the groups poses a problem in obtaining basic information on zooplankton seasonal patterns. In the present work, we used high throughput sequencing to examine the temporal and spatial distribution of the zooplankton communities inhabiting the epipelagic zone in the central Red Sea. The analysis of zooplankton assemblages collected at two sites—coastal and offshore—twice a month at several depth strata by using MANTA, Bongo and WP2 nets provides baseline information of the seasonal patterns of the zooplankton community over 1 year. We show that the seasonal fluctuation of zooplankton communities living in the upper 100 m of the water column is driven mainly by the annual changes in seawater temperature. The 18S rRNA gene was used for metabarcoding of zooplankton assemblages revealing 630 metazoan OTUs (97% similarity) in five phyla, highlighting the richness of the Red Sea community. During colder months, communities were characterized by lower richness and higher biomass than communities found during the hot season. Throughout the year the zooplankton communities were dominated by the class Maxillopoda, mainly represented by copepods and class Hydrozoa. The rise in the water temperature favors the appearance of classes Malacostraca, Cephalopoda, Gastropoda, and Saggitoidea. The present study provides essential baseline information for future monitoring and improves our knowledge of the marine ecosystem in the Red Sea while reporting the main environmental variable structuring zooplankton assemblages in this region.

  9. Metabarcoding Reveals Seasonal and Temperature-Dependent Succession of Zooplankton Communities in the Red Sea

    KAUST Repository

    Casas, Laura

    2017-08-02

    Very little is known about the composition and the annual cycle of zooplankton assemblages in the Red Sea, a confined water body characterized by a high biodiversity and endemism but at the same time one of the most understudied areas in the world in terms of marine biodiversity. This high diversity together with the lack of references for several of the groups poses a problem in obtaining basic information on zooplankton seasonal patterns. In the present work, we used high throughput sequencing to examine the temporal and spatial distribution of the zooplankton communities inhabiting the epipelagic zone in the central Red Sea. The analysis of zooplankton assemblages collected at two sites—coastal and offshore—twice a month at several depth strata by using MANTA, Bongo and WP2 nets provides baseline information of the seasonal patterns of the zooplankton community over 1 year. We show that the seasonal fluctuation of zooplankton communities living in the upper 100 m of the water column is driven mainly by the annual changes in seawater temperature. The 18S rRNA gene was used for metabarcoding of zooplankton assemblages revealing 630 metazoan OTUs (97% similarity) in five phyla, highlighting the richness of the Red Sea community. During colder months, communities were characterized by lower richness and higher biomass than communities found during the hot season. Throughout the year the zooplankton communities were dominated by the class Maxillopoda, mainly represented by copepods and class Hydrozoa. The rise in the water temperature favors the appearance of classes Malacostraca, Cephalopoda, Gastropoda, and Saggitoidea. The present study provides essential baseline information for future monitoring and improves our knowledge of the marine ecosystem in the Red Sea while reporting the main environmental variable structuring zooplankton assemblages in this region.

  10. Metabarcoding Reveals Seasonal and Temperature-Dependent Succession of Zooplankton Communities in the Red Sea

    Directory of Open Access Journals (Sweden)

    Laura Casas

    2017-08-01

    Full Text Available Very little is known about the composition and the annual cycle of zooplankton assemblages in the Red Sea, a confined water body characterized by a high biodiversity and endemism but at the same time one of the most understudied areas in the world in terms of marine biodiversity. This high diversity together with the lack of references for several of the groups poses a problem in obtaining basic information on zooplankton seasonal patterns. In the present work, we used high throughput sequencing to examine the temporal and spatial distribution of the zooplankton communities inhabiting the epipelagic zone in the central Red Sea. The analysis of zooplankton assemblages collected at two sites—coastal and offshore—twice a month at several depth strata by using MANTA, Bongo and WP2 nets provides baseline information of the seasonal patterns of the zooplankton community over 1 year. We show that the seasonal fluctuation of zooplankton communities living in the upper 100 m of the water column is driven mainly by the annual changes in seawater temperature. The 18S rRNA gene was used for metabarcoding of zooplankton assemblages revealing 630 metazoan OTUs (97% similarity in five phyla, highlighting the richness of the Red Sea community. During colder months, communities were characterized by lower richness and higher biomass than communities found during the hot season. Throughout the year the zooplankton communities were dominated by the class Maxillopoda, mainly represented by copepods and class Hydrozoa. The rise in the water temperature favors the appearance of classes Malacostraca, Cephalopoda, Gastropoda, and Saggitoidea. The present study provides essential baseline information for future monitoring and improves our knowledge of the marine ecosystem in the Red Sea while reporting the main environmental variable structuring zooplankton assemblages in this region.

  11. Charge carrier relaxation model in disordered organic semiconductors

    International Nuclear Information System (INIS)

    Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Ming

    2013-01-01

    The relaxation phenomena of charge carrier in disordered organic semiconductors have been demonstrated and investigated theoretically. An analytical model describing the charge carrier relaxation is proposed based on the pure hopping transport theory. The relation between the material disorder, electric field and temperature and the relaxation phenomena has been discussed in detail, respectively. The calculated results reveal that the increase of electric field and temperature can promote the relaxation effect in disordered organic semiconductors, while the increase of material disorder will weaken the relaxation. The proposed model can explain well the stretched-exponential law by adopting the appropriate parameters. The calculation shows a good agreement with the experimental data for organic semiconductors

  12. Modelling the fate of organic micropollutants in stormwater ponds

    DEFF Research Database (Denmark)

    Vezzaro, Luca; Eriksson, Eva; Ledin, Anna

    2011-01-01

    ). The four simulated organic stormwater MP (iodopropynyl butylcarbamate — IPBC, benzene, glyphosate and pyrene) were selected according to their different urban sources and environmental fate. This ensures that the results can be extended to other relevant stormwater pollutants. All three models use......Urban water managers need to estimate the potential removal of organic micropollutants (MP) in stormwater treatment systems to support MP pollution control strategies. This study documents how the potential removal of organic MP in stormwater treatment systems can be quantified by using multimedia...... models. The fate of four different MP in a stormwater retention pond was simulated by applying two steady-state multimedia fate models (EPI Suite and SimpleBox) commonly applied in chemical risk assessment and a dynamic multimedia fate model (Stormwater Treatment Unit Model for Micro Pollutants — STUMP...

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

    DEFF Research Database (Denmark)

    Loick-Wilde, Natalie; Dutz, Jörg; Miltner, Anja

    2012-01-01

    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...... 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...

  14. Relation between 234Th scavenging and zooplankton biomass in Mediterranean surface waters

    International Nuclear Information System (INIS)

    Schmidt, S.; Reyss, J.L.; Buat-Menard, P.; Nival, P.; Baker, M.

    1992-01-01

    Dissolved and particulate 234 Th activities were determined and phyto-and zooplankton biomass were periodically measured 8 miles off Nice (Mediterranean Sea) during spring 1987. The results show a strong variability of 234 Th distribution on short time scales in northwestern Mediterranean surface waters. The good correlation observed the zooplankton biomass and the rate of 234 Th export to deep water in particulate form is agreement with the assumption that the residence time of particulate 234 Th in oceanic surface waters is controlled by zooplankton grazing. Moreover, our results indicate the importance of salps in particular as efficient removers of small suspended particles in surface waters

  15. Modelling the fate of oxidisable organic contaminants in groundwater

    DEFF Research Database (Denmark)

    Barry, D.A.; Prommer, H.; Miller, C.T.

    2002-01-01

    modelling framework is illustrated by pertinent examples, showing the degradation of dissolved organics by microbial activity limited by the availability of nutrients or electron acceptors (i.e., changing redox states), as well as concomitant secondary reactions. Two field-scale modelling examples......Subsurface contamination by organic chemicals is a pervasive environmental problem, susceptible to remediation by natural or enhanced attenuation approaches or more highly engineered methods such as pump-and-treat, amongst others. Such remediation approaches, along with risk assessment...... are discussed, the Vejen landfill (Denmark) and an example where metal contamination is remediated by redox changes wrought by injection of a dissolved organic compound. A summary is provided of current and likely future challenges to modelling of oxidisable organics in the subsurface. (C) 2002 Elsevier Science...

  16. Drosophila melanogaster as a model organism to study nanotoxicity.

    Science.gov (United States)

    Ong, Cynthia; Yung, Lin-Yue Lanry; Cai, Yu; Bay, Boon-Huat; Baeg, Gyeong-Hun

    2015-05-01

    Drosophila melanogaster has been used as an in vivo model organism for the study of genetics and development since 100 years ago. Recently, the fruit fly Drosophila was also developed as an in vivo model organism for toxicology studies, in particular, the field of nanotoxicity. The incorporation of nanomaterials into consumer and biomedical products is a cause for concern as nanomaterials are often associated with toxicity in many in vitro studies. In vivo animal studies of the toxicity of nanomaterials with rodents and other mammals are, however, limited due to high operational cost and ethical objections. Hence, Drosophila, a genetically tractable organism with distinct developmental stages and short life cycle, serves as an ideal organism to study nanomaterial-mediated toxicity. This review discusses the basic biology of Drosophila, the toxicity of nanomaterials, as well as how the Drosophila model can be used to study the toxicity of various types of nanomaterials.

  17. Behavior is a major determinant of predation risk in zooplankton

    DEFF Research Database (Denmark)

    Almeda, Rodrigo; van Someren Gréve, Hans; Kiørboe, Thomas

    2017-01-01

    as prey for different predatory copepods. Copepods with “active” feeding behaviors (feeding-current and cruising feeders) showed significantly higher mortality from predation (~2–8 times) than similarly sized copepods with low motility feeding behavior (ambush feeders). Copepod males, which have a more...... active motile behavior than females (mate-seeking behavior), suffered a higher predation mortality than females in most of the experiments. However, the predation risk for mate-searching behavior in copepods varied depending on feeding behavior with ambush feeders consistently having the greatest......Zooplankton exhibit different small-scale motile behaviors related to feeding and mating activities. These different motile behaviors may result in different levels of predation risk, which may partially determine the structure of planktonic communities. Here, we experimentally determined predation...

  18. An evaluation of the zooplankton community at the Sheboygan River Area of Concern and non-Area of Concern comparison sites in western Lake Michigan rivers and harbors in 2016

    Science.gov (United States)

    Olds, Hayley T.; Scudder Eikenberry, Barbara C.; Burns, Daniel J.; Bell, Amanda H.

    2017-12-22

    The Great Lakes Areas of Concern (AOCs) are considered to be the most severely degraded areas within the Great Lakes basin, as defined in the Great Lakes Water Quality Agreement and amendments. Among the 43 designated AOCs are four Lake Michigan AOCs in the State of Wisconsin. The smallest of these AOCs is the Sheboygan River AOC, which was designated as an AOC because of sediment contamination from polychlorinated biphenyl compounds (PCBs), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and heavy metals. The Sheboygan River AOC has 9 of 14 possible Beneficial Use Impairments (BUIs), which must be addressed to improve overall water-quality, and to ultimately delist the AOC. One of the BUIs associated with this AOC is the “degradation of phytoplankton and zooplankton populations,” which can be removed from the list of impairments when it has been determined that zooplankton community composition and structure at the AOC do not differ significantly from communities at non-AOC comparison sites. In 2012 and 2014, the U.S. Geological Survey collected plankton (phytoplankton and zooplankton) community samples at the Sheboygan River AOC and selected non-AOC sites as part of a larger Great Lakes Restoration Initiative study evaluating both the benthos and plankton communities in all four of Wisconsin’s Lake Michigan AOCs. Although neither richness nor diversity of phytoplankton or zooplankton in the Sheboygan River AOC were found to differ significantly from the non-AOC sites in 2012, results from the 2014 data indicated that zooplankton diversity was significantly lower, and so rated as degraded, when compared to the Manitowoc and Kewaunee Rivers, two non-AOC sites of similar size, land use, and close geographic proximity.As a follow-up to the 2014 results, zooplankton samples were collected at the same locations in the AOC and non-AOC sites during three sampling trips in spring, summer, and fall 2016. An analysis of similarity indicated

  19. Aging of microplastics promotes their ingestion by marine zooplankton.

    Science.gov (United States)

    Vroom, Renske J E; Koelmans, Albert A; Besseling, Ellen; Halsband, Claudia

    2017-12-01

    Microplastics (microplastics to test their impacts, while aging processes such as weathering and biofouling alter the characteristics of plastic particles in the marine environment. We investigated zooplankton ingestion of polystyrene beads (15 and 30 μm) and fragments (≤30 μm), and tested the hypothesis that microplastics previously exposed to marine conditions (aged) are ingested at higher rates than pristine microplastics. Polystyrene beads were aged by soaking in natural local seawater for three weeks. Three zooplankton taxa ingested microplastics, excluding the copepod Pseudocalanus spp., but the proportions of individuals ingesting plastic and the number of particles ingested were taxon and life stage specific and dependent on plastic size. All stages of Calanus finmarchicus ingested polystyrene fragments. Aged microbeads were preferred over pristine ones by females of Acartia longiremis as well as juvenile copepodites CV and adults of Calanus finmarchicus. The preference for aged microplastics may be attributed to the formation of a biofilm. Such a coating, made up of natural microbes, may contain similar prey as the copepods feed on in the water column and secrete chemical exudates that aid chemodetection and thus increase the attractiveness of the particles as food items. Much of the ingested plastic was, however, egested within a short time period (2-4 h) and the survival of adult Calanus females was not affected in an 11-day exposure. Negative effects of microplastics ingestion were thus limited. Our findings emphasize, however, that aging plays an important role in the transformation of microplastics at sea and ingestion by grazers, and should thus be considered in future microplastics ingestion studies and estimates of microplastics transfer into the marine food web. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Mutant mice: experimental organisms as materialised models in biomedicine.

    Science.gov (United States)

    Huber, Lara; Keuck, Lara K

    2013-09-01

    Animal models have received particular attention as key examples of material models. In this paper, we argue that the specificities of establishing animal models-acknowledging their status as living beings and as epistemological tools-necessitate a more complex account of animal models as materialised models. This becomes particularly evident in animal-based models of diseases that only occur in humans: in these cases, the representational relation between animal model and human patient needs to be generated and validated. The first part of this paper presents an account of how disease-specific animal models are established by drawing on the example of transgenic mice models for Alzheimer's disease. We will introduce an account of validation that involves a three-fold process including (1) from human being to experimental organism; (2) from experimental organism to animal model; and (3) from animal model to human patient. This process draws upon clinical relevance as much as scientific practices and results in disease-specific, yet incomplete, animal models. The second part of this paper argues that the incompleteness of models can be described in terms of multi-level abstractions. We qualify this notion by pointing to different experimental techniques and targets of modelling, which give rise to a plurality of models for a specific disease. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Spatial arrangement of organic compounds on a model mineral surface: implications for soil organic matter stabilization.

    Science.gov (United States)

    Petridis, Loukas; Ambaye, Haile; Jagadamma, Sindhu; Kilbey, S Michael; Lokitz, Bradley S; Lauter, Valeria; Mayes, Melanie A

    2014-01-01

    The complexity of the mineral-organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise.

  2. A Framework for Formal Modeling and Analysis of Organizations

    NARCIS (Netherlands)

    Jonker, C.M.; Sharpanskykh, O.; Treur, J.; P., Yolum

    2007-01-01

    A new, formal, role-based, framework for modeling and analyzing both real world and artificial organizations is introduced. It exploits static and dynamic properties of the organizational model and includes the (frequently ignored) environment. The transition is described from a generic framework of

  3. Healing models for organizations: description, measurement, and outcomes.

    Science.gov (United States)

    Malloch, K

    2000-01-01

    Healthcare leaders are continually searching for ways to improve their ability to provide optimal healthcare services, be financially viable, and retain quality caregivers, often feeling like such goals are impossible to achieve in today's intensely competitive environment. Many healthcare leaders intuitively recognize the need for more humanistic models and the probable connection with positive patient outcomes and financial success but are hesitant to make significant changes in their organizations because of the lack of model descriptions or documented recognition of the clinical and financial advantages of humanistic models. This article describes a study that was developed in response to the increasing work in humanistic or healing environment models and the need for validation of the advantages of such models. The healthy organization model, a framework for healthcare organizations that incorporates humanistic healing values within the traditional structure, is presented as a result of the study. This model addresses the importance of optimal clinical services, financial performance, and staff satisfaction. The five research-based organizational components that form the framework are described, and key indicators of organizational effectiveness over a five-year period are presented. The resulting empirical data are strongly supportive of the healing model and reflect positive outcomes for the organization.

  4. A self-organized criticality model for plasma transport

    International Nuclear Information System (INIS)

    Carreras, B.A.; Newman, D.; Lynch, V.E.

    1996-01-01

    Many models of natural phenomena manifest the basic hypothesis of self-organized criticality (SOC). The SOC concept brings together the self-similarity on space and time scales that is common to many of these phenomena. The application of the SOC modelling concept to the plasma dynamics near marginal stability opens new possibilities of understanding issues such as Bohm scaling, profile consistency, broad band fluctuation spectra with universal characteristics and fast time scales. A model realization of self-organized criticality for plasma transport in a magnetic confinement device is presented. The model is based on subcritical resistive pressure-gradient-driven turbulence. Three-dimensional nonlinear calculations based on this model show the existence of transport under subcritical conditions. This model that includes fluctuation dynamics leads to results very similar to the running sandpile paradigm

  5. An Ising model for metal-organic frameworks

    Science.gov (United States)

    Höft, Nicolas; Horbach, Jürgen; Martín-Mayor, Victor; Seoane, Beatriz

    2017-08-01

    We present a three-dimensional Ising model where lines of equal spins are frozen such that they form an ordered framework structure. The frame spins impose an external field on the rest of the spins (active spins). We demonstrate that this "porous Ising model" can be seen as a minimal model for condensation transitions of gas molecules in metal-organic frameworks. Using Monte Carlo simulation techniques, we compare the phase behavior of a porous Ising model with that of a particle-based model for the condensation of methane (CH4) in the isoreticular metal-organic framework IRMOF-16. For both models, we find a line of first-order phase transitions that end in a critical point. We show that the critical behavior in both cases belongs to the 3D Ising universality class, in contrast to other phase transitions in confinement such as capillary condensation.

  6. Regional Persistent Organic Pollutants' Environmental Impact Assessment and Control Model

    Directory of Open Access Journals (Sweden)

    Jurgis Staniskis

    2008-10-01

    Full Text Available The sources of formation, environmental distribution and fate of persistent organic pollutants (POPs are increasingly seen as topics to be addressed and solved at the global scale. Therefore, there are already two international agreements concerning persistent organic pollutants: the Protocol of 1998 to the 1979 Convention on the Long-Range Transboundary Air Pollution on Persistent Organic Pollutants (Aarhus Protocol; and the Stockholm Convention on Persistent Organic Pollutants. For the assessment of environmental pollution of POPs, for the risk assessment, for the evaluation of new pollutants as potential candidates to be included in the POPs list of the Stokholmo or/and Aarhus Protocol, a set of different models are developed or under development. Multimedia models help describe and understand environmental processes leading to global contamination through POPs and actual risk to the environment and human health. However, there is a lack of the tools based on a systematic and integrated approach to POPs management difficulties in the region.

  7. Composition and abundance of zooplankton groups from a coral reef lagoon in Puerto Morelos, Quintana Roo, Mexico, during an annual cycle.

    Science.gov (United States)

    Alvarez-Cadena, José N; Ordóñez-López, Uriel; Almaral-Mendivil, Alma Rosa; Uicab-Sabido, Amira

    2009-09-01

    Zooplankton sampling was carried out monthly from January to December 1990 at station A near the coastline, and station B near the reef barrier, in a tropical coral reef lagoon in the Mexican Caribbean Sea. Samplings were made at midnight, near surface, with a conical net (mouth 0.40 m, mesh 330 microm) for 10 min. Salinity varied from 35.1 to 36.3 psu and temperature from 26.3 to 30.2 degrees C. The Bray-Curtis test applied to these results has defined two seasons: the dry season from November to May, and the wet season from June to October. A total of 37 zooplankton groups were found. Copepods were the most abundant contributing 49.0% of the total capture with Acartia espinata, Calanopia americana and Farranula gracilis as the most numerous. In the total zooplankton, however, cirripeds captured in only 15 samples of 24 were second in abundance (20.9%). Decapods, present all year-round and more abundant during the wet season, were third and contributed 19.2%. The rest of the groups were scarce and only amphipods (2.4%) and larvaceans (2.0%) were relatively abundant. The abundance of captured organisms correlated with the abiotic factors measured, thus, in the dry season, abundance was lower (mean 7.3 orgs/m3), while in the wet season the mean catch was 36.8 orgs/m3.

  8. Impact of chromium and aluminium pollution on the diversity of zooplankton: a case study in the Chimaliapan wetland (Ramsar site) (Lerma basin, Mexico).

    Science.gov (United States)

    García-García, Gerardo; Nandini, S; Sarma, S S S; Martínez-Jerónimo, Fernando; Jiménez-Contreras, Jorge

    2012-01-01

    Biological monitoring and the use of biotic indices are important in evaluating the health of aquatic systems. However, zooplankton are rarely included in biomonitoring protocols. We conducted a one-year study (March 2008-February 2009) at two sites from the Chimaliapan wetland, with concentrations of aluminium (Al) and chromium (Cr) above and within the permissible limits, respectively. Metals in the sediment and water were analyzed from three locations per site every two months. In addition to analyses of the abundance and diversity of rotifers, cladocerans and copepods, we sampled 11 physicochemical variables in the water and six from the sediments. The metal concentration in the polluted site (significantly above the permissible limits) ranged between 7266-8174 mg Kg(-1) of Al and 14.6-18.3 mg Kg(-1) of Cr. We found 92 species of rotifers, cladocerans and copepods. The Brillouin index for both sites ranged from 3.9-5.4, the Shannon-Wiener index from 4.2-5.5 while the Brachionus-Trichocerca ratio ranged between 1.0 and 1.7. The Wetland Zooplankton Index was significantly different among the sites; 2.63 at site 1 and 2.13 at site 2. The saprobic index was 3.2 for both sites. Data analyses using multifactorial techniques suggested that zooplankton can be used to evaluate the impact of the metals aforementioned, since these organisms are generally more sensitive than other groups and also have a high ecological relevance.

  9. Modelization of tritium transfer into the organic compartments of algae

    International Nuclear Information System (INIS)

    Bonotto, S.; Gerber, G.B.; Arapis, G.; Kirchmann, R.

    1982-01-01

    Uptake of tritium oxide and its conversion into organic tritium was studied in four different types of algae with widely varying size and growth characteristics (Acetabularia acetabulum, Boergesenia forbesii, two strains of Chlamydomonas and Dunaliella bioculata). Water in the cell and the vacuales equilibrates rapidly with external tritium water. Tritium is actively incorporated into organically bound form as the organisms grow. During the stationary phase, incorporation of tritium is slow. There exists a discrimination against the incorporation of tritium into organically bound form. A model has been elaborated taking in account these different factors. It appears that transfer of organic tritium by algae growing near the sites of release would be significant only for actively growing algae. Algae growing slowly may, however, be useful as cumulative indicators of discontinuous tritium release. (author)

  10. MODELLING CONSUMERS' DEMAND FOR ORGANIC FOOD PRODUCTS: THE SWEDISH EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Manuchehr Irandoust

    2016-07-01

    Full Text Available This paper attempts to examine a few factors characterizing consumer preferences and behavior towards organic food products in the south of Sweden using a proportional odds model which captures the natural ordering of dependent variables and any inherent nonlinearities. The findings show that consumer's choice for organic food depends on perceived benefits of organic food (environment, health, and quality and consumer's perception and attitudes towards labelling system, message framing, and local origin. In addition, high willingness to pay and income level will increase the probability to buy organic food, while the cultural differences and socio-demographic characteristics have no effect on consumer behaviour and attitudes towards organic food products. Policy implications are offered.

  11. Modeling cadmium in the feed chain and cattle organs

    OpenAIRE

    Fels-Klerx, van der, H.J.; Romkens, P.F.A.M.; Franz, E.; Raamsdonk, van, L.W.D.

    2011-01-01

    The objectives of this study were to estimate cadmium contamination levels in different scenarios related to soil characteristics and assumptions regarding cadmium accumulation in the animal tissues, using quantitative supply chain modeling. The model takes into account soil cadmium levels, soil pH, soil-to-plant transfer, animal consumption patterns, and transfer into animal organs (liver and kidneys). The model was applied to cattle up to the age of six years which were fed roughage (maize ...

  12. Lotka-Volterra competition models for sessile organisms.

    Science.gov (United States)

    Spencer, Matthew; Tanner, Jason E

    2008-04-01

    Markov models are widely used to describe the dynamics of communities of sessile organisms, because they are easily fitted to field data and provide a rich set of analytical tools. In typical ecological applications, at any point in time, each point in space is in one of a finite set of states (e.g., species, empty space). The models aim to describe the probabilities of transitions between states. In most Markov models for communities, these transition probabilities are assumed to be independent of state abundances. This assumption is often suspected to be false and is rarely justified explicitly. Here, we start with simple assumptions about the interactions among sessile organisms and derive a model in which transition probabilities depend on the abundance of destination states. This model is formulated in continuous time and is equivalent to a Lotka-Volterra competition model. We fit this model and a variety of alternatives in which transition probabilities do not depend on state abundances to a long-term coral reef data set. The Lotka-Volterra model describes the data much better than all models we consider other than a saturated model (a model with a separate parameter for each transition at each time interval, which by definition fits the data perfectly). Our approach provides a basis for further development of stochastic models of sessile communities, and many of the methods we use are relevant to other types of community. We discuss possible extensions to spatially explicit models.

  13. Biochemical studies on some zooplankton off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Rao, T.S.S.; Matondkar, S.G.P.

    Proximate biochemical analyses on twelve zooplankton species showed that protein was the predominant biochemical component followed by lipid. Carbohydrate content was very low especially in species with high water content or calcareous shell...

  14. 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.

    found to be much lower than the values presently used in routine conversion factors. Such factors are now essentially needed for accounting role of zooplankton in sediment trap collections in Arabian Sea region...

  15. 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.

    .6%). Invertebrate larvae, luciferied shrimps, cladocerans and chaetognaths were the other common zooplankton groups. Distribution and abundance of majority of constituent groups and species were influenced by various hydrographical characteristics of the environment....

  16. A Biogeographic Assessment of the Stellwagen Bank National Marine Sanctuary - Kriged Predictive Map of Zooplankton Samples

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton communities have been well studied in the northeast Atlantic (Sherman et al., 1983) and on Georges Bank within the Gulf of Maine (Bigelow, 1927; Davis,...

  17. Cost of reproduction in selected species of zooplankton (rotifers and cladocerans)

    NARCIS (Netherlands)

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

    2002-01-01

    Reproduction is an energetically costly biological process. Among the freshwater zooplankton, rotifers and cladocerans reproduce parthenogenetically and the cost of reproduction can be estimated using the life table data from demographic studies. Reduced probability of future survival or future

  18. Comparative account on zooplankton in polluted and unpolluted estuaries of Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, B.N.; Gajbhiye, S.N.; JiyalalRam, M.J.; Nair, V.R.

    An assessment of the zooplankton biomass and composition in Kolak Par, Damanganga and Auranga estuaries was made. Among these four rivers pollution is severe in the first two, moderate in Damanganga and good water quality prevailed in Auranga...

  19. Zooplankton studies in Visakhapatnam harbour and nearshore waters, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rathod, V.; Sarma, V.V.

    Distribution of zooplankton biomass in the waters studied showed remarkable variations. The faunal composition was very diverse and the number of species present was more especially during late pre- and post-monsoon seasons with conspicuous decrease...

  20. 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.

    , siphonophores, chaetognaths and fish eggs were the other common taxa. Zooplankton population was never dominated by a single group. Swarms of copepods (Temora turbinata), cladocerans (Evadne tergestina), and pteropods (Creseis acicula) occurred in the nutrient...

  1. Spatial and temporal habitat partitioning by zooplankton in the Bornholm Basin (central Baltic Sea)

    DEFF Research Database (Denmark)

    Schultz, J.; Peck, M.A.; Barz, K.

    2012-01-01

    taxa (Bosmina coregoni maritima, Acartia spp., Pseudocalanus spp., Temora longicornis, Synchaeta spp.) contributed >10% to the zooplankton community composition. The appearance of cladocerans was mainly correlated with the phenology of thermocline development in the spring. The cladoceran B. coregoni...

  2. Spatial zonation of zooplankton in the northwestern Arabian Sea: A multivariate approach

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.

    Latitudinal variation in abundance, diversity, dominance pattern and zonation of the major groups of zooplankton was studied n the coastal waters of northwestern Arabian Sea, between 25°44' N and 10°44' N. Maxwell Boltzmann Statistic...

  3. Relative abundance and diel variation of zooplankton from south west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Santhakumari, V.; Peter, K.J.

    abundant group, of which calanoids predominated. A swarm of the hydromedusan species, Aequorea conica, (181/m sup(-3)) was seen at night. Quantitative and qualitative variations of various zooplankton groups from six stations in relation to selected physico...

  4. A Biogeographic Assessment of the Stellwagen Bank National Marine Sanctuary - Kriged Probability Map of Zooplankton Samples

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton communities have been well studied in the northeast Atlantic (Sherman et al., 1983) and on Georges Bank within the Gulf of Maine (Bigelow, 1927; Davis,...

  5. Modeling Temperature Dependent Singlet Exciton Dynamics in Multilayered Organic Nanofibers

    DEFF Research Database (Denmark)

    de Sousa, Leonardo Evaristo; de Oliveira Neto, Pedro Henrique; Kjelstrup-Hansen, Jakob

    2018-01-01

    Organic nanofibers have shown potential for application in optoelectronic devices because of the tunability of their optical properties. These properties are influenced by the electronic structure of the molecules that compose the nanofibers, but also by the behavior of the excitons generated...... dynamics in multilayered organic nanofibers. By simulating absorption and emission spectra, the possible Förster transitions are identified. Then, a Kinetic Monte Carlo (KMC) model is employed in combination with a genetic algorithm to theoretically reproduce time resolved photoluminescence measurements...

  6. Foraging mode and prey size spectra of suspension-feeding copepods and other zooplankton

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2016-01-01

    Prey size spectra of suspension-feeding zooplankton may be predicted from foraging mode and a mechanistic understanding of prey perception and capture. I examine this for suspension-feeding copepods where 2 foraging modes can be distinguished: ambush feeding and active (i.e. cruising and feeding-...... the prediction. I also make qualitative predictions of food size spectra in zooplankton with other prey perception mechanisms that accord with observations....

  7. Indicator Properties of Baltic Zooplankton for Classification of Environmental Status within Marine Strategy Framework Directive.

    Science.gov (United States)

    Gorokhova, Elena; Lehtiniemi, Maiju; Postel, Lutz; Rubene, Gunta; Amid, Callis; Lesutiene, Jurate; Uusitalo, Laura; Strake, Solvita; Demereckiene, Natalja

    2016-01-01

    The European Marine Strategy Framework Directive requires the EU Member States to estimate the level of anthropogenic impacts on their marine systems using 11 Descriptors. Assessing food web response to altered habitats is addressed by Descriptor 4 and its indicators, which are being developed for regional seas. However, the development of simple foodweb indicators able to assess the health of ecologically diverse, spatially variable and complex interactions is challenging. Zooplankton is a key element in marine foodwebs and thus comprise an important part of overall ecosystem health. Here, we review work on zooplankton indicator development using long-term data sets across the Baltic Sea and report the main findings. A suite of zooplankton community metrics were evaluated as putative ecological indicators that track community state in relation to Good Environmental Status (GES) criteria with regard to eutrophication and fish feeding conditions in the Baltic Sea. On the basis of an operational definition of GES, we propose mean body mass of zooplankton in the community in combination with zooplankton stock measured as either abundance or biomass to be applicable as an integrated indicator that could be used within the Descriptor 4 in the Baltic Sea. These metrics performed best in predicting zooplankton being in-GES when considering all datasets evaluated. However, some other metrics, such as copepod biomass, the contribution of copepods to the total zooplankton biomass or biomass-based Cladocera: Copepoda ratio, were equally reliable or even superior in certain basin-specific assessments. Our evaluation suggests that in several basins of the Baltic Sea, zooplankton communities currently appear to be out-of-GES, being comprised by smaller zooplankters and having lower total abundance or biomass compared to the communities during the reference conditions; however, the changes in the taxonomic structure underlying these trends vary widely across the sea basins due to

  8. Electrochemical model of the polyaniline based organic memristive device

    International Nuclear Information System (INIS)

    Demin, V. A.; Erokhin, V. V.; Kashkarov, P. K.; Kovalchuk, M. V.

    2014-01-01

    The electrochemical organic memristive device with polyaniline active layer is a stand-alone device designed and realized for reproduction of some synapse properties in the innovative electronic circuits, including the neuromorphic networks capable for learning. In this work, a new theoretical model of the polyaniline memristive is presented. The developed model of organic memristive functioning was based on the detailed consideration of possible electrochemical processes occuring in the active zone of this device. Results of the calculation have demonstrated not only the qualitative explanation of the characteristics observed in the experiment but also the quantitative similarities of the resultant current values. It is shown how the memristive could behave at zero potential difference relative to the reference electrode. This improved model can establish a basis for the design and prediction of properties of more complicated circuits and systems (including stochastic ones) based on the organic memristive devices

  9. A model-independent view of the mature organization

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, M.; Langston, D.

    1996-12-31

    Over the last 10 years, industry has been dealing with the issues of process and organizational maturity. This focus on process is driven by the success that manufacturing organizations have had implementing the management principles of W. Edwards Deming and Joseph M. Juran. The organizational-maturity focus is driven by organizations striving to be ISO 9000 compliant or to achieve a specific level on one of the maturity models. Unfortunately, each of the models takes a specific view into what is a very broad arena. That is to say, each model addresses only a specific subset of the characteristics of maturity. This paper attempts to extend beyond these specific views to answer the general question, What is a mature organization and its relationship to Quantitative management and statistical process control?

  10. Net-zooplankton abundance and biomass from Annaba Bay (SW Mediterranean Sea under estuarine influences

    Directory of Open Access Journals (Sweden)

    M. OUNISSI

    2016-07-01

    Full Text Available Zooplankton samples were collected in Annaba Bay (Algeria from January 2009-March 2011 at three coastal sites differently affected by estuarine plumes and external currents. Aim of this survey was to analyze zooplankton composition, abundance and biomass and compare the results with previous studies to reveal possible populations and environmental changes. The mean zooplankton abundance varied between 1,200-6,000 ind. m-3 and biomass 6.70-25.70 mg DW m-3, according to the site. Copepods constituted the main fraction of zooplankton community, and Oithona similis and Paracalanus indicus successively dominated during autumn-winter and spring-summer. The dinoflagellate Noctiluca scintillans was one of the major zooplankton components, and developed high numbers during February-April, becoming common in neritic and coastal regions. The singularity of the zooplankton from Annaba Bay is the prevalence of P. indicus throughout the entire bay and the decrease in Acartia discaudata and A. clausi (with respect to previous years, possibly replaced by A. negligens. Additionally, Oithona nana abundance markedly decreased with the large development of O. similis. Annaba Bay also differs from other similar Mediterranean coastal areas by the large development of Centropages ponticus populations during the warm period. Among the identified copepod species, the alien species Pseudodiaptomus australiensis and P. arabicus are reported for the first time in the Mediterranean Sea. The occurrence of copepodid V stages of P. australiensis suggests that this species survives and reproduces in Annaba Bay, but so far without developing an abundant population.

  11. Productivity, trophic levels and size spectra of zooplankton in northern Norwegian shelf regions

    Science.gov (United States)

    Zhou, Meng; Tande, Kurt S.; Zhu, Yiwu; Basedow, Sünnje

    2009-10-01

    Many studies have been conducted in northern Norwegian shelf regions to assess distributions and abundances of zooplankton in the last decade using towed Scanfish-conductivity, temperature and depth sensors (CTD)-optical plankton counter (OPC), and plankton nets. Significant progresses have been made in understanding dominant species, life histories and behavior, and in using size-structured data to identify dominant species in a certain size range. Using these Scanfish-CTD-OPC data, the analysis of zooplankton community size structures, compositions and their relationships with water types is made along the shelf region from Lofoten, North Cape to Varangerfjorden. From the relationships between the water types and zooplankton communities, the transports and exchanges of zooplankton communities between the Norwegian Coastal and Norwegian Atlantic Waters in regions near Malangsgrunnen and Nordvestbanken are examined. The biovolume (biomass) spectra are further analyzed for the productivity, trophic levels and seasonality of communities in these regions, indicating a steeper slope of the biovolume spectrum for a community dominated by herbivorous species in spring and a flatter slope for a community dominated by carnivorous-omnivorous species in winter. The comparison with the zooplankton biovolume spectra obtained in areas west of Antarctic Peninsula is made to examine and understand the differences in the zooplankton biovolume spectra, their trophic dynamics and potential human impacts between different regions.

  12. Molecular analysis of the replication program in unicellular model organisms.

    Science.gov (United States)

    Raghuraman, M K; Brewer, Bonita J

    2010-01-01

    Eukaryotes have long been reported to show temporal programs of replication, different portions of the genome being replicated at different times in S phase, with the added possibility of developmentally regulated changes in this pattern depending on species and cell type. Unicellular model organisms, primarily the budding yeast Saccharomyces cerevisiae, have been central to our current understanding of the mechanisms underlying the regulation of replication origins and the temporal program of replication in particular. But what exactly is a temporal program of replication, and how might it arise? In this article, we explore this question, drawing again on the wealth of experimental information in unicellular model organisms.

  13. 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

  14. Self-organized Criticality Model for Ocean Internal Waves

    International Nuclear Information System (INIS)

    Wang Gang; Hou Yijun; Lin Min; Qiao Fangli

    2009-01-01

    In this paper, we present a simple spring-block model for ocean internal waves based on the self-organized criticality (SOC). The oscillations of the water blocks in the model display power-law behavior with an exponent of -2 in the frequency domain, which is similar to the current and sea water temperature spectra in the actual ocean and the universal Garrett and Munk deep ocean internal wave model [Geophysical Fluid Dynamics 2 (1972) 225; J. Geophys. Res. 80 (1975) 291]. The influence of the ratio of the driving force to the spring coefficient to SOC behaviors in the model is also discussed. (general)

  15. The effects of power plant passage on zooplankton mortalities: Eight years of study at the Donald C. Cook Nuclear Plant

    International Nuclear Information System (INIS)

    Evans, M.S.; Warren, G.J.; Page, D.I.

    1986-01-01

    Zooplankton mortalities resulting from passage through the Donald C. Cook Nuclear Plant (southeastern Lake Michigan) were studied over an 8-year (1975-1982) period. The power plant operated at a low ΔT ( 0 C) and discharge water temperatures did not exceed 35 0 C (except September 1978). While zooplankton mortalities were significantly greater in discharge than intake waters, differences were small, averaging <3%. There was no evidence of additional delayed effects on zooplankton mortality following plant passage. There was no relationship between zooplankton mortalities and temperature (ΔT, discharge water temperature). Mechanical stresses appeared to be the major cause of zooplankton mortality. The authors hypothesize that fish predation, rather than power plant operation, probably was the major source of zooplankton mortality in inshore waters during much of the year. (author)

  16. Device model investigation of bilayer organic light emitting diodes

    International Nuclear Information System (INIS)

    Crone, B. K.; Davids, P. S.; Campbell, I. H.; Smith, D. L.

    2000-01-01

    Organic materials that have desirable luminescence properties, such as a favorable emission spectrum and high luminescence efficiency, are not necessarily suitable for single layer organic light-emitting diodes (LEDs) because the material may have unequal carrier mobilities or contact limited injection properties. As a result, single layer LEDs made from such organic materials are inefficient. In this article, we present device model calculations of single layer and bilayer organic LED characteristics that demonstrate the improvements in device performance that can occur in bilayer devices. We first consider an organic material where the mobilities of the electrons and holes are significantly different. The role of the bilayer structure in this case is to move the recombination away from the electrode that injects the low mobility carrier. We then consider an organic material with equal electron and hole mobilities but where it is not possible to make a good contact for one carrier type, say electrons. The role of a bilayer structure in this case is to prevent the holes from traversing the device without recombining. In both cases, single layer device limitations can be overcome by employing a two organic layer structure. The results are discussed using the calculated spatial variation of the carrier densities, electric field, and recombination rate density in the structures. (c) 2000 American Institute of Physics

  17. Green Algae as Model Organisms for Biological Fluid Dynamics

    Science.gov (United States)

    Goldstein, Raymond E.

    2015-01-01

    In the past decade, the volvocine green algae, spanning from the unicellular Chlamydomonas to multicellular Volvox, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 μm to several millimeters), their geometric regularity, the ease with which they can be cultured, and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.

  18. There Is No Simple Model of the Plasma Membrane Organization

    Science.gov (United States)

    Bernardino de la Serna, Jorge; Schütz, Gerhard J.; Eggeling, Christian; Cebecauer, Marek

    2016-01-01

    Ever since technologies enabled the characterization of eukaryotic plasma membranes, heterogeneities in the distributions of its constituents were observed. Over the years this led to the proposal of various models describing the plasma membrane organization such as lipid shells, picket-and-fences, lipid rafts, or protein islands, as addressed in numerous publications and reviews. Instead of emphasizing on one model we in this review give a brief overview over current models and highlight how current experimental work in one or the other way do not support the existence of a single overarching model. Instead, we highlight the vast variety of membrane properties and components, their influences and impacts. We believe that highlighting such controversial discoveries will stimulate unbiased research on plasma membrane organization and functionality, leading to a better understanding of this essential cellular structure. PMID:27747212

  19. An Ontology for Modeling Complex Inter-relational Organizations

    Science.gov (United States)

    Wautelet, Yves; Neysen, Nicolas; Kolp, Manuel

    This paper presents an ontology for organizational modeling through multiple complementary aspects. The primary goal of the ontology is to dispose of an adequate set of related concepts for studying complex organizations involved in a lot of relationships at the same time. In this paper, we define complex organizations as networked organizations involved in a market eco-system that are playing several roles simultaneously. In such a context, traditional approaches focus on the macro analytic level of transactions; this is supplemented here with a micro analytic study of the actors' rationale. At first, the paper overviews enterprise ontologies literature to position our proposal and exposes its contributions and limitations. The ontology is then brought to an advanced level of formalization: a meta-model in the form of a UML class diagram allows to overview the ontology concepts and their relationships which are formally defined. Finally, the paper presents the case study on which the ontology has been validated.

  20. Zebrabase: An intuitive tracking solution for aquatic model organisms

    OpenAIRE

    Oltova, Jana; Bartunek, Petr; Machonova, Olga; Svoboda, Ondrej; Skuta, Ctibor; Jindrich, Jindrich

    2018-01-01

    Small fish species, like zebrafish or medaka, are constantly gaining popularity in basic research and disease modeling as a useful alternative to rodent model organisms. However, the tracking options for fish within a facility are rather limited. Here, we present an aquatic species tracking database, Zebrabase, developed in our zebrafish research and breeding facility that represents a practical and scalable solution and an intuitive platform for scientists, fish managers and caretakers, in b...

  1. A model of virtual organization for corporate visibility and ...

    African Journals Online (AJOL)

    This paper considers the existing numerous research in business, Information and Communication Technology (ICT), examines a theoretical framework for value creation in a virtual world. Following a proposed model, a new strategic paradigm is created for corporate value; and virtual organization (VO) apply the use of ...

  2. Modeling of the transient mobility in disordered organic semiconductors

    NARCIS (Netherlands)

    Germs, W.C.; Van der Holst, J.M.M.; Van Mensfoort, S.L.M.; Bobbert, P.A.; Coehoorn, R.

    2011-01-01

    In non-steady-state experiments, the electrical response of devicesbased on disordered organic semiconductors often shows a large transient contribution due to relaxation of the out-of-equilibrium charge-carrier distribution. We have developed a model describing this process, based only on the

  3. An Integrated Model for Effective Knowledge Management in Chinese Organizations

    Science.gov (United States)

    An, Xiaomi; Deng, Hepu; Wang, Yiwen; Chao, Lemen

    2013-01-01

    Purpose: The purpose of this paper is to provide organizations in the Chinese cultural context with a conceptual model for an integrated adoption of existing knowledge management (KM) methods and to improve the effectiveness of their KM activities. Design/methodology/approaches: A comparative analysis is conducted between China and the western…

  4. Waste Reduction Model (WARM) Resources for Small Businesses and Organizations

    Science.gov (United States)

    This page provides a brief overview of how EPA’s Waste Reduction Model (WARM) can be used by small businesses and organizations. The page includes a brief summary of uses of WARM for the audience and links to other resources.

  5. SOMPROF: A vertically explicit soil organic matter model

    NARCIS (Netherlands)

    Braakhekke, M.C.; Beer, M.; Hoosbeek, M.R.; Kruijt, B.; Kabat, P.

    2011-01-01

    Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to

  6. Modeling growth of specific spoilage organisms in tilapia ...

    African Journals Online (AJOL)

    Tilapia is an important aquatic fish, but severe spoilage of tilapia is most likely related to the global aquaculture. The spoilage is mostly caused by specific spoilage organisms (SSO). Therefore, it is very important to use microbial models to predict the growth of SSO in tilapia. This study firstly verified Pseudomonas and Vibrio ...

  7. There Is No Simple Model of the Plasma Membrane Organization

    Czech Academy of Sciences Publication Activity Database

    de la serna, J. B.; Schütz, G.; Eggeling, Ch.; Cebecauer, Marek

    2016-01-01

    Roč. 4, SEP 2016 (2016), 106 ISSN 2296-634X R&D Projects: GA ČR GA15-06989S Institutional support: RVO:61388955 Keywords : plasma membrane * membrane organization models * heterogeneous distribution Subject RIV: CF - Physical ; Theoretical Chemistry

  8. Transfer and accumulation of 106Ru from phytoplankton (Dunaliella bioculata) to zooplankton (Artemia salina)

    International Nuclear Information System (INIS)

    Izumo, Yoshiro; Takase, Akira

    1982-01-01

    106 Ru is one of the most abundant radionuclides to be released from the unclear-spent fuel reprocessing plant to oceans. This paper deals with transfer and accumulation of the radionuclide from phytoplankton (Dunaliella) to zooplankton (Artemia) in the graizing food chain of marine organisms. Each plankton was reared in the radioactive sea water A (filtrated and circulated through sandy mud, and the radioactive concentration decreased and atteined to constant after addition of 106 Ru), B (not filtrated and circulated, and the radioactive concentration decreased and atteined to constant) and C (not filtrated and circulated, the radioactive concentration decreased, but did not attein to constant), respectively, and investigated accumulations of 106 Ru. Then, accumulations of 106 Ru in Artemia by the ingestion of each diet (Dunaliella) contaminated with 106 Ru in each water, were investigated and compared with those from each water. Concentration factors of 106 Ru for the planktons reared in the radioactive sea waters were different among these waters. The difference can be attributable to that of physicochemical states of 106 Ru in the waters. It was found that 106 Ru would be accumulated by Artemia from the water A about 10 times higher than from the contaminated diet (Dunaliella) in this water, however from the contaminated diet (Dunaliella) in the water B about 2.2 times higher than from the last water. (author)

  9. Lamination of organic solar cells and organic light emitting devices: Models and experiments

    International Nuclear Information System (INIS)

    Oyewole, O. K.; Yu, D.; Du, J.; Asare, J.; Fashina, A.; Anye, V. C.; Zebaze Kana, M. G.; Soboyejo, W. O.

    2015-01-01

    In this paper, a combined experimental, computational, and analytical approach is used to provide new insights into the lamination of organic solar cells and light emitting devices at macro- and micro-scales. First, the effects of applied lamination force (on contact between the laminated layers) are studied. The crack driving forces associated with the interfacial cracks (at the bi-material interfaces) are estimated along with the critical interfacial crack driving forces associated with the separation of thin films, after layer transfer. The conditions for successful lamination are predicted using a combination of experiments and computational models. Guidelines are developed for the lamination of low-cost organic electronic structures

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

    Science.gov (United States)

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

    2004-09-01

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

  11. On uses, misuses and potential abuses of fractal analysis in zooplankton behavioral studies: A review, a critique and a few recommendations

    Science.gov (United States)

    Seuront, Laurent

    2015-08-01

    Fractal analysis is increasingly used to describe, and provide further understanding to, zooplankton swimming behavior. This may be related to the fact that fractal analysis and the related fractal dimension D have the desirable properties to be independent of measurement scale and to be very sensitive to even subtle behavioral changes that may be undetectable to other behavioral variables. As early claimed by Coughlin et al. (1992), this creates "the need for fractal analysis" in behavioral studies, which has hence the potential to become a valuable tool in zooplankton behavioral ecology. However, this paper stresses that fractal analysis, as well as the more elaborated multifractal analysis, is also a risky business that may lead to irrelevant results, without paying extreme attention to a series of both conceptual and practical steps that are all likely to bias the results of any analysis. These biases are reviewed and exemplified on the basis of the published literature, and remedial procedures are provided not only for geometric and stochastic fractal analyses, but also for the more complicated multifractal analysis. The concept of multifractals is finally introduced as a direct, objective and quantitative tool to identify models of motion behavior, such as Brownian motion, fractional Brownian motion, ballistic motion, Lévy flight/walk and multifractal random walk. I finally briefly review the state of this emerging field in zooplankton behavioral research.

  12. Spatial variation of the zooplankton community in the western tropical Pacific Ocean during the summer of 2014

    Science.gov (United States)

    Yang, Guang; Li, Chaolun; Wang, Yanqing; Wang, Xiaocheng; Dai, Luping; Tao, Zhencheng; Ji, Peng

    2017-03-01

    Knowledge of the zooplankton community in the western tropical Pacific Ocean is poor compared to that of the communities in the central and eastern Pacific Ocean. The zooplankton composition, abundance, biomass and community structure in the western Pacific Ocean were studied based on data collected during a synoptic cruise (August-September 2014). Four zooplankton communities were determined via cluster analysis, and these four clusters were mainly spatially related to four different currents: the Luzon Current (LC), Subtropical Countercurrent (STCC), North Equatorial Current (NEC) and North Equatorial Countercurrent (NECC). The estimated mean abundance and biomass of the zooplankton for the whole surveyed area were 146.7±178.1 ind/m3 and 36.9±40.3 mg/m3, respectively. The zooplankton abundance was dominated by small copepods, such as Clausocalanus furcatus, C. pergens, Oncaea mediterranea and Oithona plumifera. The zooplankton abundance and biomass values were lowest in the STCC region and highest in the NECC region. BEST analysis based on surface environmental factors showed that chlorophyll a (chl a), pH, temperature and salinity were the environmental variables that best explained the distribution pattern of the zooplankton community (pw=0.372). The zooplankton abundance was higher south of the salinity front at 16°N, in accordance with the relatively higher nutrient and chl a levels. Maximum zooplankton biomass was found in regions on the periphery of the cyclonic Mindanao Eddy (ME) and anticyclonic Halmahera Eddy (HE).

  13. Sustainable Organic Farming For Environmental Health A Social Development Model

    Directory of Open Access Journals (Sweden)

    Ijun Rijwan Susanto

    2015-05-01

    Full Text Available ABSTRACT In this study the researcher attempted 1 to understand the basic features of organic farming in The Paguyuban Pasundans Cianjur 2 to describe and understand how the stakeholders were are able to internalize the challenges of organic farming on their lived experiences in the community 3 to describe and understand how the stakeholders were are able to internalize and applied the values of benefits of organic farming in support of environmental health on their lived experiences in the community 4 The purpose was to describe and understand how the stakeholders who are able to articulate their ideas regarding the model of sustainable organic farming 5 The Policy Recommendation for Organic Farming. The researcher employed triangulation thorough finding that provides breadth and depth to an investigation offering researchers a more accurate picture of the phenomenon. In the implementation of triangulation researchers conducted several interviews to get saturation. After completion of the interview results are written compiled and shown to the participants to check every statement by every participant. In addition researchers also checked the relevant documents and direct observation in the field The participants of this study were the stakeholders namely 1 The leader of Paguyuban Pasundans Organic Farmer Cianjur PPOFC 2 Members of Paguyuban Pasundans Organic FarmersCianjur 3 Leader of NGO 4 Government officials of agriculture 5 Business of organic food 6 and Consumer of organic food. Generally the findings of the study revealed the following 1 PPOFC began to see the reality as the impact of modern agriculture showed in fertility problems due to contaminated soil by residues of agricultural chemicals such as chemical fertilizers and chemical pesticides. So he wants to restore the soil fertility through environmentally friendly of farming practices 2 the challenges of organic farming on their lived experiences in the community farmers did not

  14. On the influence of the exposure model on organ doses

    International Nuclear Information System (INIS)

    Drexler, G.; Eckerl, H.

    1988-01-01

    Based on the design characteristics of the MIRD-V phantom, two sex-specific adult phantoms, ADAM and EVA were introduced especially for the calculation of organ doses resulting from external irradiation. Although the body characteristics of all the phantoms are in good agreement with those of the reference man and woman, they have some disadvantages related to the location and shape of organs and the form of the whole body. To overcome these disadvantages related to the location and shape of organs and form of the whole body. To overcome these disadvantages related to the location and shape of organs and the form of the whole body. To overcome these disadvantages and to obtain more realistic phantoms, a technique based on computer tomographic data (voxel-phantom) was developed. This technique allows any physical phantom or real body to be converted into computer files. The improvements are of special importance with regard to the skeleton, because a better modeling of the bone surfaces and separation of hard bone and bone marrow can be achieved. For photon irradiation, the sensitivity of the model on organ doses or the effective dose equivalent is important for operational radiation protection

  15. Modeling of secondary organic aerosol yields from laboratory chamber data

    Directory of Open Access Journals (Sweden)

    M. N. Chan

    2009-08-01

    Full Text Available Laboratory chamber data serve as the basis for constraining models of secondary organic aerosol (SOA formation. Current models fall into three categories: empirical two-product (Odum, product-specific, and volatility basis set. The product-specific and volatility basis set models are applied here to represent laboratory data on the ozonolysis of α-pinene under dry, dark, and low-NOx conditions in the presence of ammonium sulfate seed aerosol. Using five major identified products, the model is fit to the chamber data. From the optimal fitting, SOA oxygen-to-carbon (O/C and hydrogen-to-carbon (H/C ratios are modeled. The discrepancy between measured H/C ratios and those based on the oxidation products used in the model fitting suggests the potential importance of particle-phase reactions. Data fitting is also carried out using the volatility basis set, wherein oxidation products are parsed into volatility bins. The product-specific model is most likely hindered by lack of explicit inclusion of particle-phase accretion compounds. While prospects for identification of the majority of SOA products for major volatile organic compounds (VOCs classes remain promising, for the near future empirical product or volatility basis set models remain the approaches of choice.

  16. 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.

  17. Regional zooplankton dispersal provides spatial insurance for ecosystem function.

    Science.gov (United States)

    Symons, Celia C; Arnott, Shelley E

    2013-05-01

    Changing environmental conditions are affecting diversity and ecosystem function globally. Theory suggests that dispersal from a regional species pool may buffer against changes in local community diversity and ecosystem function after a disturbance through the establishment of functionally redundant tolerant species. The spatial insurance provided by dispersal may decrease through time after environmental change as the local community monopolizes resources and reduces community invasibility. To test for evidence of the spatial insurance hypothesis and to determine the role dispersal timing plays in this response we conducted a field experiment using crustacean zooplankton communities in a subarctic region that is expected to be highly impacted by climate change - Churchill, Canada. Three experiments were conducted where nutrients, salt, and dispersal were manipulated. The three experiments differed in time-since-disturbance that the dispersers were added. We found that coarse measures of diversity (i.e. species richness, evenness, and Shannon-Weiner diversity) were generally resistant to large magnitude disturbances, and that dispersal had the most impact on diversity when dispersers were added shortly after disturbance. Ecosystem functioning (chl-a) was degraded in disturbed communities, but dispersal recovered ecosystem function to undisturbed levels. This spatial insurance for ecosystem function was mediated through changes in community composition and the relative abundance of functional groups. Results suggest that regional diversity and habitat connectivity will be important in the future to maintain ecosystem function by introducing functionally redundant species to promote compensatory dynamics. © 2012 Blackwell Publishing Ltd.

  18. Accounting for microbial habitats in modeling soil organic matter dynamics

    Science.gov (United States)

    Chenu, Claire; Garnier, Patricia; Nunan, Naoise; Pot, Valérie; Raynaud, Xavier; Vieublé, Laure; Otten, Wilfred; Falconer, Ruth; Monga, Olivier

    2017-04-01

    The extreme heterogeneity of soils constituents, architecture and inhabitants at the microscopic scale is increasingly recognized. Microbial communities exist and are active in a complex 3-D physical framework of mineral and organic particles defining pores of various sizes, more or less inter-connected. This results in a frequent spatial disconnection between soil carbon, energy sources and the decomposer organisms and a variety of microhabitats that are more or less suitable for microbial growth and activity. However, current biogeochemical models account for C dynamics at the macroscale (cm, m) and consider time- and spatially averaged relationships between microbial activity and soil characteristics. Different modelling approaches have intended to account for this microscale heterogeneity, based either on considering aggregates as surrogates for microbial habitats, or pores. Innovative modelling approaches are based on an explicit representation of soil structure at the fine scale, i.e. at µm to mm scales: pore architecture and their saturation with water, localization of organic resources and of microorganisms. Three recent models are presented here, that describe the heterotrophic activity of either bacteria or fungi and are based upon different strategies to represent the complex soil pore system (Mosaic, LBios and µFun). These models allow to hierarchize factors of microbial activity in soil's heterogeneous architecture. Present limits of these approaches and challenges are presented, regarding the extensive information required on soils at the microscale and to up-scale microbial functioning from the pore to the core scale.

  19. [Biomechanical modeling of pelvic organ mobility: towards personalized medicine].

    Science.gov (United States)

    Cosson, Michel; Rubod, Chrystèle; Vallet, Alexandra; Witz, Jean-François; Brieu, Mathias

    2011-11-01

    Female pelvic mobility is crucial for urinary, bowel and sexual function and for vaginal delivery. This mobility is ensured by a complex organ suspension system composed of ligaments, fascia and muscles. Impaired pelvic mobility affects one in three women of all ages and can be incapacitating. Surgical management has a high failure rate, largely owing to poor knowledge of the organ support system, including the barely discernible ligamentous system. We propose a 3D digital model of the pelvic cavity based on MRI images and quantitative tools, designed to locate the pelvic ligaments. We thus obtain a coherent anatomical and functional model which can be used to analyze pelvic pathophysiology. This work represents a first step towards creating a tool for localizing and characterizing the source of pelvic imbalance. We examine possible future applications of this model, in terms of personalized therapy and prevention.

  20. 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.

  1. Eutrophication and warming effects on long-term variation of zooplankton in Lake Biwa

    Directory of Open Access Journals (Sweden)

    C. H. Hsieh

    2011-05-01

    Full Text Available We compiled and analyzed long-term (1961–2005 zooplankton community data in response to environmental variations in Lake Biwa. Environmental data indicate that Lake Biwa had experienced eutrophication (according to the total phosphorus concentration in the late 1960s and recovered to a normal trophic status around 1985, and then has exhibited warming since 1990. Total zooplankton abundance showed a significant correlation with total phytoplankton biomass. Following a classic pattern, the cladoceran/calanoid and cyclopoid/calanoid abundance ratio was related positively to eutrophication. The zooplankton community exhibited a significant response to the boom and bust of phytoplankton biomass as a consequence of eutrophication-reoligotriphication and warming. Moreover, our analyses suggest that the Lake Biwa ecosystem exhibited a hierarchical response across trophic levels; that is, higher trophic levels may show a more delayed response or no response to eutrophication than lower ones.

    We tested the hypothesis that the phytoplankton community can better explain the variation of the zooplankton community than bulk environmental variables, considering that the phytoplankton community may directly affect the zooplankton succession through predator-prey interactions. Using a variance partition approach, however, we did not find strong evidence to support this hypothesis. We further aggregated zooplankton according to their feeding types (herbivorous, carnivorous, omnivorous, and parasitic and taxonomic groups, and analyzed the aggregated data. While the pattern remains similar, the results are less clear comparing the results based on finely resolved data. Our research suggests that zooplankton can be bio-indicators of environmental changes; however, the efficacy depends on data resolution.

  2. Modeling Secondary Organic Aerosol Formation From Emissions of Combustion Sources

    Science.gov (United States)

    Jathar, Shantanu Hemant

    Atmospheric aerosols exert a large influence on the Earth's climate and cause adverse public health effects, reduced visibility and material degradation. Secondary organic aerosol (SOA), defined as the aerosol mass arising from the oxidation products of gas-phase organic species, accounts for a significant fraction of the submicron atmospheric aerosol mass. Yet, there are large uncertainties surrounding the sources, atmospheric evolution and properties of SOA. This thesis combines laboratory experiments, extensive data analysis and global modeling to investigate the contribution of semi-volatile and intermediate volatility organic compounds (SVOC and IVOC) from combustion sources to SOA formation. The goals are to quantify the contribution of these emissions to ambient PM and to evaluate and improve models to simulate its formation. To create a database for model development and evaluation, a series of smog chamber experiments were conducted on evaporated fuel, which served as surrogates for real-world combustion emissions. Diesel formed the most SOA followed by conventional jet fuel / jet fuel derived from natural gas, gasoline and jet fuel derived from coal. The variability in SOA formation from actual combustion emissions can be partially explained by the composition of the fuel. Several models were developed and tested along with existing models using SOA data from smog chamber experiments conducted using evaporated fuel (this work, gasoline, fischertropschs, jet fuel, diesels) and published data on dilute combustion emissions (aircraft, on- and off-road gasoline, on- and off-road diesel, wood burning, biomass burning). For all of the SOA data, existing models under-predicted SOA formation if SVOC/IVOC were not included. For the evaporated fuel experiments, when SVOC/IVOC were included predictions using the existing SOA model were brought to within a factor of two of measurements with minor adjustments to model parameterizations. Further, a volatility

  3. Predicting long-term organic carbon dynamics in organically amended soils using the CQESTR model

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, Cesar; Polo, Alfredo [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencias Agrarias; Gollany, Hero T. [Columbia Plateau Conservation Research Center, Pendleton, OR (United States). USDA-ARS; Baldoni, Guido; Ciavatta, Claudio [Bologna Univ. (Italy). Dept. of Agroenvironmental Sciences and Technologies

    2012-04-15

    Purpose: The CQESTR model is a process-based C model recently developed to simulate soil organic matter (SOM) dynamics and uses readily available or easily measurable input parameters. The current version of CQESTR (v. 2.0) has been validated successfully with a number of datasets from agricultural sites in North America but still needs to be tested in other geographic areas and soil types under diverse organic management systems. Materials and methods: We evaluated the predictive performance of CQESTR to simulate long-term (34 years) soil organic C (SOC) changes in a SOM-depleted European soil either unamended or amended with solid manure, liquid manure, or crop residue. Results and discussion: Measured SOC levels declined over the study period in the unamended soil, remained constant in the soil amended with crop residues, and tended to increase in the soils amended with manure, especially with solid manure. Linear regression analysis of measured SOC contents and CQESTR predictions resulted in a correlation coefficient of 0.626 (P < 0.001) and a slope and an intercept not significantly different from 1 and 0, respectively (95% confidence level). The mean squared deviation and root mean square error were relatively small. Simulated values fell within the 95% confidence interval of the measured SOC, and predicted errors were mainly associated with data scattering. Conclusions: The CQESTR model was shown to predict, with a reasonable degree of accuracy, the organic C dynamics in the soils examined. The CQESTR performance, however, could be improved by adding an additional parameter to differentiate between pre-decomposed organic amendments with varying degrees of stability. (orig.)

  4. Multimodel inference to quantify the relative importance of abiotic factors in the population dynamics of marine zooplankton

    Science.gov (United States)

    Everaert, Gert; Deschutter, Yana; De Troch, Marleen; Janssen, Colin R.; De Schamphelaere, Karel

    2018-05-01

    The effect of multiple stressors on marine ecosystems remains poorly understood and most of the knowledge available is related to phytoplankton. To partly address this knowledge gap, we tested if combining multimodel inference with generalized additive modelling could quantify the relative contribution of environmental variables on the population dynamics of a zooplankton species in the Belgian part of the North Sea. Hence, we have quantified the relative contribution of oceanographic variables (e.g. water temperature, salinity, nutrient concentrations, and chlorophyll a concentrations) and anthropogenic chemicals (i.e. polychlorinated biphenyls) to the density of Acartia clausi. We found that models with water temperature and chlorophyll a concentration explained ca. 73% of the population density of the marine copepod. Multimodel inference in combination with regression-based models are a generic way to disentangle and quantify multiple stressor-induced changes in marine ecosystems. Future-oriented simulations of copepod densities suggested increased copepod densities under predicted environmental changes.

  5. Organized versus self-organized criticality in the abelian sandpile model

    OpenAIRE

    Fey-den Boer, AC Anne; Redig, FHJ Frank

    2005-01-01

    We define stabilizability of an infinite volume height configuration and of a probability measure on height configurations. We show that for high enough densities, a probability measure cannot be stabilized. We also show that in some sense the thermodynamic limit of the uniform measures on the recurrent configurations of the abelian sandpile model (ASM) is a maximal element of the set of stabilizable measures. In that sense the self-organized critical behavior of the ASM can be understood in ...

  6. IT Business Value Model for Information Intensive Organizations

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Gastaud Maçada

    2012-01-01

    Full Text Available Many studies have highlighted the capacity Information Technology (IT has for generating value for organizations. Investments in IT made by organizations have increased each year. Therefore, the purpose of the present study is to analyze the IT Business Value for Information Intensive Organizations (IIO - e.g. banks, insurance companies and securities brokers. The research method consisted of a survey that used and combined the models from Weill and Broadbent (1998 and Gregor, Martin, Fernandez, Stern and Vitale (2006. Data was gathered using an adapted instrument containing 5 dimensions (Strategic, Informational, Transactional, Transformational and Infra-structure with 27 items. The instrument was refined by employing statistical techniques such as Exploratory and Confirmatory Factorial Analysis through Structural Equations (first and second order Model Measurement. The final model is composed of four factors related to IT Business Value: Strategic, Informational, Transactional and Transformational, arranged in 15 items. The dimension Infra-structure was excluded during the model refinement process because it was discovered during interviews that managers were unable to perceive it as a distinct dimension of IT Business Value.

  7. Scalability of Sustainable Business Models in Hybrid Organizations

    Directory of Open Access Journals (Sweden)

    Adam Jabłoński

    2016-02-01

    Full Text Available The dynamics of change in modern business create new mechanisms for company management to determine their pursuit and the achievement of their high performance. This performance maintained over a long period of time becomes a source of ensuring business continuity by companies. An ontological being enabling the adoption of such assumptions is such a business model that has the ability to generate results in every possible market situation and, moreover, it has the features of permanent adaptability. A feature that describes the adaptability of the business model is its scalability. Being a factor ensuring more work and more efficient work with an increasing number of components, scalability can be applied to the concept of business models as the company’s ability to maintain similar or higher performance through it. Ensuring the company’s performance in the long term helps to build the so-called sustainable business model that often balances the objectives of stakeholders and shareholders, and that is created by the implemented principles of value-based management and corporate social responsibility. This perception of business paves the way for building hybrid organizations that integrate business activities with pro-social ones. The combination of an approach typical of hybrid organizations in designing and implementing sustainable business models pursuant to the scalability criterion seems interesting from the cognitive point of view. Today, hybrid organizations are great spaces for building effective and efficient mechanisms for dialogue between business and society. This requires the appropriate business model. The purpose of the paper is to present the conceptualization and operationalization of scalability of sustainable business models that determine the performance of a hybrid organization in the network environment. The paper presents the original concept of applying scalability in sustainable business models with detailed

  8. A taxonomy of nursing care organization models in hospitals.

    Science.gov (United States)

    Dubois, Carl-Ardy; D'Amour, Danielle; Tchouaket, Eric; Rivard, Michèle; Clarke, Sean; Blais, Régis

    2012-08-28

    Over the last decades, converging forces in hospital care, including cost-containment policies, rising healthcare demands and nursing shortages, have driven the search for new operational models of nursing care delivery that maximize the use of available nursing resources while ensuring safe, high-quality care. Little is known, however, about the distinctive features of these emergent nursing care models. This article contributes to filling this gap by presenting a theoretically and empirically grounded taxonomy of nursing care organization models in the context of acute care units in Quebec and comparing their distinctive features. This study was based on a survey of 22 medical units in 11 acute care facilities in Quebec. Data collection methods included questionnaire, interviews, focus groups and administrative data census. The analytical procedures consisted of first generating unit profiles based on qualitative and quantitative data collected at the unit level, then applying hierarchical cluster analysis to the units' profile data. The study identified four models of nursing care organization: two professional models that draw mainly on registered nurses as professionals to deliver nursing services and reflect stronger support to nurses' professional practice, and two functional models that draw more significantly on licensed practical nurses (LPNs) and assistive staff (orderlies) to deliver nursing services and are characterized by registered nurses' perceptions that the practice environment is less supportive of their professional work. This study showed that medical units in acute care hospitals exhibit diverse staff mixes, patterns of skill use, work environment design, and support for innovation. The four models reflect not only distinct approaches to dealing with the numerous constraints in the nursing care environment, but also different degrees of approximations to an "ideal" nursing professional practice model described by some leaders in the

  9. A taxonomy of nursing care organization models in hospitals

    Science.gov (United States)

    2012-01-01

    Background Over the last decades, converging forces in hospital care, including cost-containment policies, rising healthcare demands and nursing shortages, have driven the search for new operational models of nursing care delivery that maximize the use of available nursing resources while ensuring safe, high-quality care. Little is known, however, about the distinctive features of these emergent nursing care models. This article contributes to filling this gap by presenting a theoretically and empirically grounded taxonomy of nursing care organization models in the context of acute care units in Quebec and comparing their distinctive features. Methods This study was based on a survey of 22 medical units in 11 acute care facilities in Quebec. Data collection methods included questionnaire, interviews, focus groups and administrative data census. The analytical procedures consisted of first generating unit profiles based on qualitative and quantitative data collected at the unit level, then applying hierarchical cluster analysis to the units’ profile data. Results The study identified four models of nursing care organization: two professional models that draw mainly on registered nurses as professionals to deliver nursing services and reflect stronger support to nurses’ professional practice, and two functional models that draw more significantly on licensed practical nurses (LPNs) and assistive staff (orderlies) to deliver nursing services and are characterized by registered nurses’ perceptions that the practice environment is less supportive of their professional work. Conclusions This study showed that medical units in acute care hospitals exhibit diverse staff mixes, patterns of skill use, work environment design, and support for innovation. The four models reflect not only distinct approaches to dealing with the numerous constraints in the nursing care environment, but also different degrees of approximations to an “ideal” nursing professional practice

  10. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) SOURCE CHARACTERIZATION IN THE LOUISIANA BIGHT

    Science.gov (United States)

    Chromophoric dissolved organic matter (CDOM) in the Mississippi plume region may have several distinct sources: riverine (terrestrial soils), wetland (terrestrial plants), biological production (phytoplankton, zooplankton, microbial), and sediments. Complex mixing, photodegradati...

  11. Zooplankton and associated data from CTD casts from 05 May 1997 to 04 March 1998 as part of the Columbia River Land-Margin Ecosystem Research (NODC Accession 0000384)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton densities, zooplankton species identities, chlorophyll, transmissivity, and temperature data were collected from the ROBERT GORDON SPROUL, WECOMA, and...

  12. Ingestion of microplastics by natural zooplankton groups in the northern South China Sea.

    Science.gov (United States)

    Sun, Xiaoxia; Li, Qingjie; Zhu, Mingliang; Liang, Junhua; Zheng, Shan; Zhao, Yongfang

    2017-02-15

    The ingestion of microplastics by five natural zooplankton groups in the northern South China Sea was studied for the first time and two types of sampling nets (505μm and 160μm in mesh size) were compared. The microplastics were detected in zooplankton sampled from 16 stations, with the fibrous microplastics accounting for the largest proportion (70%). The main component of the found microplastics was polyester. The average length of the microplastics was 125μm and 167μm for Nets I and II, respectively. The encounter rates of microplastics/zooplankton increased with trophic levels. The average encounter rate of microplastics/zooplankton was 5%, 15%, 34%, 49%, and 120% for Net I, and 8%, 21%, 47%, 60%, and 143% for Net II for copepods, chaetognaths, jellyfish, shrimp, and fish larvae, respectively. The average abundance of microplastics that were ingested by zooplankton was 4.1pieces/m 3 for Net I and 131.5pieces/m 3 for Net II. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Some ecological implications of a neem (azadirachtin) insecticide disturbance to zooplankton communities in forest pond enclosures.

    Science.gov (United States)

    Kreutzweiser, David P; Sutton, Trent M; Back, Richard C; Pangle, Kevin L; Thompson, Dean G

    2004-04-28

    A neem-based insecticide, Neemix 4.5, was applied to forest pond enclosures at concentrations of 10, 17, and 28 microg l(-1) azadirachtin (the active ingredient). At these test concentrations, significant, concentration-dependent reductions in numbers of adult copepods were observed, but immature copepod and cladoceran populations were unaffected. There was no evidence of recovery of adult copepods within the sampling season (May to October). The ecological significance of this disturbance to the zooplankton community was examined by determining biomass as a measure of food availability for higher predators, plankton community respiration, dissolved oxygen (DO) concentrations, and conductivity as functional indicators of ecosystem stress, and zooplankton food web stability as a measure of effects on trophic structure. The selective removal or reduction of adult copepods was sufficient to measurably reduce total zooplankton biomass for several weeks mid-season. During the period of maximal impact (about 4-9 weeks after the applications), total plankton community respiration was significantly reduced, and this appeared to contribute to significant, concentration-dependent increases in dissolved oxygen and decreases in conductivity among treated enclosures. The reductions in adult copepods resulted in negative effects on zooplankton food web stability through eliminations of a trophic link and reduced interactions and connectance. Comparing the results here to those from a previous study with tebufenozide, which was selectively toxic to cladocerans and had little effect on food web stability, indicates that differential sensitivity among taxa can influence the ecological significance of pesticide effects on zooplankton communities.

  14. Zooplankton diversity of a protected and vulnerable wetland system in southern South America (Llancanelo area, Argentina

    Directory of Open Access Journals (Sweden)

    D. Sabina D’Ambrosio

    2016-02-01

    Full Text Available Abstract In arid regions, climatic conditions exert a great control on the aquatic systems present, but recent changes in climate have produced an enhanced salinization of the aquatic environments located there. Consequently, a major reduction in biodiversity would be expected in those wetlands that were originally fresh water. Salinity is a principal cause of reduced biodiversity particularly in zooplankton because few of those species can adapt to the salt pressure of saline environments. Therefore, the aim of this study was to gain essential information on the diversity of aquatic invertebrates in Llancanelo basin by focussing the analysis on the zooplankton community and exploring seasonal and spatial differences in the zooplankton assemblages of this vulnerable wetland system within an arid region of Argentina. Seasonal samples were taken at nine sites in the basin (a shallow lake, 4 springs, streams, and the Malargüe River. A total of 45 species were identified. The zooplankton abundance in the lake displayed a clear seasonal contrast and was higher than that recorded in the springs and lotic environments. Boeckella poopoensis, Fabrea salina, and Brachionus plicatilis predominated in the lake, indicating their halophilia. The presence of the crustaceans Alona sp., Macrocyclops albidus, and Paracyclops fimbriatus was restricted to the springs; whereas Notholca labis and Notholca squamula were found only in running water. The zooplankton species richness in the Llancanelo area is low because of both the salt content in the lake and the irregularity of freshwater entry in all locations during the annual cycle.

  15. Zooplankton and ichthyoplankton distribution on the southern Brazilian shelf: an overview

    Directory of Open Access Journals (Sweden)

    Rubens M. Lopes

    2006-06-01

    Full Text Available The southern Brazilian coast is the major fishery ground for the Brazilian sardine (Sardinella brasiliensis, a species responsible for up to 40% of marine fish catches in the region. Fish spawning and recruitment are locally influenced by seasonal advection of nutrient-rich waters from both inshore and offshore sources. Plankton communities are otherwise controlled by regenerative processes related to the oligotrophic nature of the Tropical Water from the Brazil Current. As recorded in other continental margins, zooplankton species diversity increases towards outer shelf and open ocean waters. Peaks of zooplankton biomass and ichthyoplankton abundance are frequent on the inner shelf, either at upwelling sites or off large estuarine systems. However, meandering features of the Brazil Current provide an additional mechanism of upward motion of the cold and nutrient-rich South Atlantic Central Water, increasing phyto- and zooplankton biomass and production on mid- and outer shelves. Cold neritic waters originating off Argentina, and subtropical waters from the Subtropical Convergence exert a strong seasonal influence on zooplankton and ichthyoplankton distribution towards more southern areas. This brief review highlights the need for further experimental studies on zooplankton life cycle strategies in order to understand the major processes controlling food web dynamics in this shelf ecosystem.

  16. Dynamics of zooplankton community of Lake Tarasmozero in long-term anthropogenic pollution

    Directory of Open Access Journals (Sweden)

    Kuchko Yaroslav Alexandrovich

    2014-11-01

    Full Text Available In the article the results of zooplankton studies in Lake Tarasmozero (Lizhma river basin are presented. Wastes from the trout-breeding complex "Kedrozero" have been collected in this pond since 1992. The obtained data showed that from 1989 to 2012 a number of changes in zooplankton community take place and it is the evidence of the gradual increase in the trophic status of the reservoir. The average biomass of zooplankton increased from 500 to 1000 mg/m3. According to the trophic index (Myaemets, 1979, Tarasmozero is replaced into the category of mesotrophic water reservoirs (0.5 - 1.0. Saprobity index raised from 0.95 to 1.42. In the composition of the zooplankton there noted such species, as Polyarthra luminosa, Filinia longiseta, Trichocerca insignis, Daphnia longispina, Cyclops kolensis, which serve as indicators of increased trophic level in the conditions of moderate latitudes. After the trout farm started off, Bcrus/Brot indicator considerably decreased indicating to increasing role of rotifers in the formation of the total biomass of the zooplankton. Currently, the dominant species include D. longispina, Bosmina longirostris, Mesocyclops leuckarti, Asplanchna priodonta. In spite of the fact that the current changes are not catastrophic, it is reasonable to monitor regularly the initial links of the trophic chain of the reservoir ecosystem

  17. Variability of zooplankton communities at Condor seamount and surrounding areas, Azores (NE Atlantic)

    Science.gov (United States)

    Carmo, Vanda; Santos, Mariana; Menezes, Gui M.; Loureiro, Clara M.; Lambardi, Paolo; Martins, Ana

    2013-12-01

    Seamounts are common topographic features around the Azores archipelago (NE Atlantic). Recently there has been increasing research effort devoted to the ecology of these ecosystems. In the Azores, the mesozooplankon is poorly studied, particularly in relation to these seafloor elevations. In this study, zooplankton communities in the Condor seamount area (Azores) were investigated during March, July and September 2010. Samples were taken during both day and night with a Bongo net of 200 µm mesh that towed obliquely within the first 100 m of the water column. Total abundance, biomass and chlorophyll a concentrations did not vary with sampling site or within the diel cycle but significant seasonal variation was observed. Moreover, zooplankton community composition showed the same strong seasonal pattern regardless of spatial or daily variability. Despite seasonal differences, the zooplankton community structure remained similar for the duration of this study. Seasonal variability better explained our results than mesoscale spatial variability. Spatial homogeneity is probably related with island proximity and local dynamics over Condor seamount. Zooplankton literature for the region is sparse, therefore a short review of the most important zooplankton studies from the Azores is also presented.

  18. Molecular analysis of the replication program in unicellular model organisms

    OpenAIRE

    Raghuraman, M. K.; Brewer, Bonita J.

    2010-01-01

    Eukaryotes have long been reported to show temporal programs of replication, different portions of the genome being replicated at different times in S phase, with the added possibility of developmentally regulated changes in this pattern depending on species and cell type. Unicellular model organisms, primarily the budding yeast Saccharomyces cerevisiae, have been central to our current understanding of the mechanisms underlying the regulation of replication origins and the temporal program o...

  19. Understanding rare disease pathogenesis: a grand challenge for model organisms.

    Science.gov (United States)

    Hieter, Philip; Boycott, Kym M

    2014-10-01

    In this commentary, Philip Hieter and Kym Boycott discuss the importance of model organisms for understanding pathogenesis of rare human genetic diseases, and highlight the work of Brooks et al., "Dysfunction of 60S ribosomal protein L10 (RPL10) disrupts neurodevelopment and causes X-linked microcephaly in humans," published in this issue of GENETICS. Copyright © 2014 by the Genetics Society of America.

  20. Acoustic backscatter models of fish: Gradual or punctuated evolution

    Science.gov (United States)

    Horne, John K.

    2004-05-01

    Sound-scattering characteristics of aquatic organisms are routinely investigated using theoretical and numerical models. Development of the inverse approach by van Holliday and colleagues in the 1970s catalyzed the development and validation of backscatter models for fish and zooplankton. As the understanding of biological scattering properties increased, so did the number and computational sophistication of backscatter models. The complexity of data used to represent modeled organisms has also evolved in parallel to model development. Simple geometric shapes representing body components or the whole organism have been replaced by anatomically accurate representations derived from imaging sensors such as computer-aided tomography (CAT) scans. In contrast, Medwin and Clay (1998) recommend that fish and zooplankton should be described by simple theories and models, without acoustically superfluous extensions. Since van Holliday's early work, how has data and computational complexity influenced accuracy and precision of model predictions? How has the understanding of aquatic organism scattering properties increased? Significant steps in the history of model development will be identified and changes in model results will be characterized and compared. [Work supported by ONR and the Alaska Fisheries Science Center.

  1. Quasi-dynamic model for an organic Rankine cycle

    International Nuclear Information System (INIS)

    Bamgbopa, Musbaudeen O.; Uzgoren, Eray

    2013-01-01

    Highlights: • Study presents a simplified transient modeling approach for an ORC under variable heat input. • The ORC model is presented as a synthesis of its models of its sub-components. • The model is compared to benchmark numerical simulations and experimental data at different stages. - Abstract: When considering solar based thermal energy input to an organic Rankine cycle (ORC), intermittent nature of the heat input does not only adversely affect the power output but also it may prevent ORC to operate under steady state conditions. In order to identify reliability and efficiency of such systems, this paper presents a simplified transient modeling approach for an ORC operating under variable heat input. The approach considers that response of the system to heat input variations is mainly dictated by the evaporator. Consequently, overall system is assembled using dynamic models for the heat exchangers (evaporator and condenser) and static models of the pump and the expander. In addition, pressure drop within heat exchangers is neglected. The model is compared to benchmark numerical and experimental data showing that the underlying assumptions are reasonable for cases where thermal input varies in time. Furthermore, the model is studied on another configuration and mass flow rates of both the working fluid and hot water and hot water’s inlet temperature to the ORC unit are shown to have direct influence on the system’s response

  2. Sordaria macrospora, a model organism to study fungal cellular development.

    Science.gov (United States)

    Engh, Ines; Nowrousian, Minou; Kück, Ulrich

    2010-12-01

    During the development of multicellular eukaryotes, the processes of cellular growth and organogenesis are tightly coordinated. Since the 1940s, filamentous fungi have served as genetic model organisms to decipher basic mechanisms underlying eukaryotic cell differentiation. Here, we focus on Sordaria macrospora, a homothallic ascomycete and important model organism for developmental biology. During its sexual life cycle, S. macrospora forms three-dimensional fruiting bodies, a complex process involving the formation of different cell types. S. macrospora can be used for genetic, biochemical and cellular experimental approaches since diverse tools, including fluorescence microscopy, a marker recycling system and gene libraries, are available. Moreover, the genome of S. macrospora has been sequenced and allows functional genomics analyses. Over the past years, our group has generated and analysed a number of developmental mutants which has greatly enhanced our fundamental understanding about fungal morphogenesis. In addition, our recent research activities have established a link between developmental proteins and conserved signalling cascades, ultimately leading to a regulatory network controlling differentiation processes in a eukaryotic model organism. This review summarizes the results of our recent findings, thus advancing current knowledge of the general principles and paradigms underpinning eukaryotic cell differentiation and development. Copyright © 2010 Elsevier GmbH. All rights reserved.

  3. Aging, neurogenesis, and caloric restriction in different model organisms.

    Science.gov (United States)

    Arslan-Ergul, Ayca; Ozdemir, A Tugrul; Adams, Michelle M

    2013-08-01

    Brain aging is a multifactorial process that is occurring across multiple cognitive domains. A significant complaint that occurs in the elderly is a decrement in learning and memory ability. Both rodents and zebrafish exhibit a similar problem with memory during aging. The neurobiological changes that underlie this cognitive decline are complex and undoubtedly influenced by many factors. Alterations in the birth of new neurons and neuron turnover may contribute to age-related cognitive problems. Caloric restriction is the only non-genetic intervention that reliably increases life span and healthspan across multiple organisms although the molecular mechanisms are not well-understood. Recently the zebrafish has become a popular model organism for understanding the neurobiological consequences but to date very little work has been performed. Similarly, few studies have examined the effects of dietary restriction in zebrafish. Here we review the literature related to memory decline, neurogenesis, and caloric restriction across model organisms and suggest that zebrafish has the potential to be an important animal model for understanding the complex interactions between age, neurobiological changes in the brain, and dietary regimens or their mimetics as interventions.

  4. Turbulence and Self-Organization Modeling Astrophysical Objects

    CERN Document Server

    Marov, Mikhail Ya

    2013-01-01

    This book focuses on the development of continuum models of natural turbulent media. It provides a theoretical approach to the solutions of different problems related to the formation, structure and evolution of astrophysical and geophysical objects. A stochastic modeling approach is used in the mathematical treatment of these problems, which reflects self-organization processes in open dissipative systems. The authors also consider examples of ordering for various objects in space throughout their evolutionary processes. This volume is aimed at graduate students and researchers in the fields of mechanics, astrophysics, geophysics, planetary and space science.

  5. Multisensor sampling of pelagic ecosystem variables in a coastal environment to estimate zooplankton grazing impact

    Science.gov (United States)

    Sutton, Tracey; Hopkins, Thomas; Remsen, Andrew; Burghart, Scott

    2001-01-01

    Sampling was conducted on the west Florida continental shelf ecosystem modeling site to estimate zooplankton grazing impact on primary production. Samples were collected with the high-resolution sampler, a towed array bearing electronic and optical sensors operating in tandem with a paired net/bottle verification system. A close biological-physical coupling was observed, with three main plankton communities: 1. a high-density inshore community dominated by larvaceans coincident with a salinity gradient; 2. a low-density offshore community dominated by small calanoid copepods coincident with the warm mixed layer; and 3. a high-density offshore community dominated by small poecilostomatoid and cyclopoid copepods and ostracods coincident with cooler, sub-pycnocline oceanic water. Both high-density communities were associated with relatively turbid water. Applying available grazing rates from the literature to our abundance data, grazing pressure mirrored the above bio-physical pattern, with the offshore sub-pycnocline community contributing ˜65% of grazing pressure despite representing only 19% of the total volume of the transect. This suggests that grazing pressure is highly localized, emphasizing the importance of high-resolution sampling to better understand plankton dynamics. A comparison of our grazing rate estimates with primary production estimates suggests that mesozooplankton do not control the fate of phytoplankton over much of the area studied (<5% grazing of daily primary production), but "hot spots" (˜25-50% grazing) do occur which may have an effect on floral composition.

  6. Zooplankton data collected from SWIMMER/DIVER in Coastal Waters of Hawaii; 07 February 1995 to 15 March 1995 (NODC Accession 9800149)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net casts in Coastal Waters of Hawaii from SWIMMER / DIVER. Data were collected from 07 February 1995 to 15 March...

  7. Temporal and spatial distribution of microcrustacean zooplankton in relation to turbidity and other environmental factors in a large tropical lake (L. Tana, Ethiopia)

    NARCIS (Netherlands)

    Dejen, E.; Vijverberg, J.; Nagelkerke, L.A.J.; Sibbing, F.A.

    2004-01-01

    The spatial and seasonal distribution of microcrustacean zooplankton of Lake Tana (Ethiopia) was monthly studied for 2 years. Concurrently, various environmental parameters were measured and related to zooplankton distribution. Canonical Correspondence Analysis (CCA) was used to estimate the

  8. Zooplankton, chemical, and other data collected from THOMAS G. THOMPSON in Arabian Sea; 09 January 1995 to 07 April 1995 (NODC Accession 9800109)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton, chemical, and other data were collected using zooplankton net casts in Arabian Sea from THOMAS G. THOMPSON. Data were collected from 09 January 1995 to...

  9. Zooplankton data collected from unidentified platforms in Coastal Waters of Washington / Oregon; 22 May 1979 to 06 August 1980 (NODC Accession 9800143)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton data were collected using zooplankton net and bottle casts in Coastal Waters of Washington / Oregon from unidentified platforms from Canada. Data were...

  10. Conceptual hierarchical modeling to describe wetland plant community organization

    Science.gov (United States)

    Little, A.M.; Guntenspergen, G.R.; Allen, T.F.H.

    2010-01-01

    Using multivariate analysis, we created a hierarchical modeling process that describes how differently-scaled environmental factors interact to affect wetland-scale plant community organization in a system of small, isolated wetlands on Mount Desert Island, Maine. We followed the procedure: 1) delineate wetland groups using cluster analysis, 2) identify differently scaled environmental gradients using non-metric multidimensional scaling, 3) order gradient hierarchical levels according to spatiotem-poral scale of fluctuation, and 4) assemble hierarchical model using group relationships with ordination axes and post-hoc tests of environmental differences. Using this process, we determined 1) large wetland size and poor surface water chemistry led to the development of shrub fen wetland vegetation, 2) Sphagnum and water chemistry differences affected fen vs. marsh / sedge meadows status within small wetlands, and 3) small-scale hydrologic differences explained transitions between forested vs. non-forested and marsh vs. sedge meadow vegetation. This hierarchical modeling process can help explain how upper level contextual processes constrain biotic community response to lower-level environmental changes. It creates models with more nuanced spatiotemporal complexity than classification and regression tree procedures. Using this process, wetland scientists will be able to generate more generalizable theories of plant community organization, and useful management models. ?? Society of Wetland Scientists 2009.

  11. Silkworm: A Promising Model Organism in Life Science.

    Science.gov (United States)

    Meng, Xu; Zhu, Feifei; Chen, Keping

    2017-09-01

    As an important economic insect, silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) has numerous advantages in life science, such as low breeding cost, large progeny size, short generation time, and clear genetic background. Additionally, there are rich genetic resources associated with silkworms. The completion of the silkworm genome has further accelerated it to be a modern model organism in life science. Genomic studies showed that some silkworm genes are highly homologous to certain genes related to human hereditary disease and, therefore, are a candidate model for studying human disease. In this article, we provided a review of silkworm as an important model in various research areas, including human disease, screening of antimicrobial agents, environmental safety monitoring, and antitumor studies. In addition, the application potentiality of silkworm model in life sciences was discussed. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America.

  12. An Instructional Development Model for Global Organizations: The GOaL Model.

    Science.gov (United States)

    Hara, Noriko; Schwen, Thomas M.

    1999-01-01

    Presents an instructional development model, GOaL (Global Organization Localization), for use by global organizations. Topics include gaps in language, culture, and needs; decentralized processes; collaborative efforts; predetermined content; multiple perspectives; needs negotiation; learning within context; just-in-time training; and bilingual…

  13. ZOOPLANKTON DIVERSITY AND ITS RELATIONSHIP WITH PHYSICO-CHEMICAL PARAMETERS IN MANI RESERVOIR OF WESTERN GHATS, REGION, HOSANAGAR TALUK, SHIVAMOGA DISTRICT KARNATAKA, INDIA

    Directory of Open Access Journals (Sweden)

    D. N. Veerendra

    2012-01-01

    Full Text Available Studies on relationship between zooplankton abundance and water quality parameter in Mani reservoir were made between January 2008 and December 2008. In the current investigation, impact of different physico-chemical parameters on zooplankton population was found. Ten genera of zooplankton were identified. The relationship between zooplankton and water quality parameters was varied from place to place depending upon the condition of the reservoir water.

  14. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    KAUST Repository

    Kü rten, Benjamin; Al-Aidaroos, Ali M.; Kurten, Saskia; El-Sherbiny, Mohsen M.; Devassy, Reny P.; Struck, Ulrich; Zarokanellos, Nikolaos; Jones, Burton; Hansen, Thomas; Bruss, Gerd; Sommer, Ulrich

    2015-01-01

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one

  15. ZOOPLANKTON COMMUNITY STRUCTURE OF THE SEA SURFACE MICROLAYER NEAR NUCLEAR POWER PLANTS AND MARINE FISH CULTURE ZONES IN DAYA BAY

    Institute of Scientific and Technical Information of China (English)

    杨宇峰; 王肇鼎; 潘明祥; 焦念志

    2002-01-01

    The authors' surveys in May-June 1999 (two cruises) at six sampling stations near nuclear power plants (NPP) and marine fish culture zones in Daya Bay, Guangdong, revealed species composition, densities and body-size of thesea surface microlayer (SM) zooplankton (>35 μm). Results showed that protozoans and copepod nauplii were the predominant components, accounting for 65.40% to95.56% of total zooplankton in abundance. The size-frequency distributions showed that the frequency of micro-zooplankton (0.02-0.2 mm) reached 0.8235. The SM zooplankton community structure revealed in the present study was quite different from that revealed by investigations in the 1980s in Daya Bay. Difference of sampling method has important influence on the obtained zooplankton community structure. SM zooplankton consisted of micro- and mesozooplankton (0.2-2.0 mm), with micro-zooplankton being predominant. Some possible cause-effect relations between the zooplankton community structure and mariculture, nuclear power plants cooling systems and sampling method are discussed.``

  16. 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; Heuschele, Jan

    2014-01-01

    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...

  17. Dryout modeling in support of the organic tank safety project

    International Nuclear Information System (INIS)

    Simmons, C.S.

    1998-08-01

    This work was performed for the Organic Tank Safety Project to evaluate the moisture condition of the waste surface organic-nitrate bearing tanks that are classified as being conditionally safe because sufficient water is present. This report describes the predictive modeling procedure used to predict the moisture content of waste in the future, after it has been subjected to dryout caused by water vapor loss through passive ventilation. This report describes a simplified procedure for modeling the drying out of tank waste. Dryout occurs as moisture evaporates from the waste into the headspace and then exits the tank through ventilation. The water vapor concentration within the waste of the headspace is determined by the vapor-liquid equilibrium, which depends on the waste's moisture content and temperature. This equilibrium has been measured experimentally for a variety of waste samples and is described by a curve called the water vapor partial pressure isotherm. This curve describes the lowering of the partial pressure of water vapor in equilibrium with the waste relative to pure water due to the waste's chemical composition and hygroscopic nature. Saltcake and sludge are described by two distinct calculations that emphasize the particular physical behavior or each. A simple, steady-state model is devised for each type to obtain the approximate drying behavior. The report shows the application of the model to Tanks AX-102, C-104, and U-105

  18. Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter.

    Science.gov (United States)

    Last, Kim S; Hobbs, Laura; Berge, Jørgen; Brierley, Andrew S; Cottier, Finlo

    2016-01-25

    In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological migration have historically been considered non-existent [1]. However, diel vertical migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as yet, unexplained. Here, we present evidence of an unexpected uniform behavior across the entire Arctic, in fjord, shelf, slope and open sea, where vertical migrations of zooplankton are driven by lunar illumination. A shift from solar-day (24-hr period) to lunar-day (24.8-hr period) vertical migration takes place in winter when the moon rises above the horizon. Further, mass sinking of zooplankton from the surface waters and accumulation at a depth of ∼50 m occurs every 29.5 days in winter, coincident with the periods of full moon. Moonlight may enable predation of zooplankton by carnivorous zooplankters, fish, and birds now known to feed during the polar night [4]. Although primary production is almost nil at this time, lunar vertical migration (LVM) may facilitate monthly pulses of carbon remineralization, as they occur continuously in illuminated mesopelagic systems [5], due to community respiration of carnivorous and detritivorous zooplankton. The extent of LVM during the winter suggests that the behavior is highly conserved and adaptive and therefore needs to be considered as "baseline" zooplankton activity in a changing Arctic ocean [6-9]. VIDEO ABSTRACT. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. 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.

  20. Mesoscopic kinetic Monte Carlo modeling of organic photovoltaic device characteristics

    Science.gov (United States)

    Kimber, Robin G. E.; Wright, Edward N.; O'Kane, Simon E. J.; Walker, Alison B.; Blakesley, James C.

    2012-12-01

    Measured mobility and current-voltage characteristics of single layer and photovoltaic (PV) devices composed of poly{9,9-dioctylfluorene-co-bis[N,N'-(4-butylphenyl)]bis(N,N'-phenyl-1,4-phenylene)diamine} (PFB) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) have been reproduced by a mesoscopic model employing the kinetic Monte Carlo (KMC) approach. Our aim is to show how to avoid the uncertainties common in electrical transport models arising from the need to fit a large number of parameters when little information is available, for example, a single current-voltage curve. Here, simulation parameters are derived from a series of measurements using a self-consistent “building-blocks” approach, starting from data on the simplest systems. We found that site energies show disorder and that correlations in the site energies and a distribution of deep traps must be included in order to reproduce measured charge mobility-field curves at low charge densities in bulk PFB and F8BT. The parameter set from the mobility-field curves reproduces the unipolar current in single layers of PFB and F8BT and allows us to deduce charge injection barriers. Finally, by combining these disorder descriptions and injection barriers with an optical model, the external quantum efficiency and current densities of blend and bilayer organic PV devices can be successfully reproduced across a voltage range encompassing reverse and forward bias, with the recombination rate the only parameter to be fitted, found to be 1×107 s-1. These findings demonstrate an approach that removes some of the arbitrariness present in transport models of organic devices, which validates the KMC as an accurate description of organic optoelectronic systems, and provides information on the microscopic origins of the device behavior.

  1. MIANN models in medicinal, physical and organic chemistry.

    Science.gov (United States)

    González-Díaz, Humberto; Arrasate, Sonia; Sotomayor, Nuria; Lete, Esther; Munteanu, Cristian R; Pazos, Alejandro; Besada-Porto, Lina; Ruso, Juan M

    2013-01-01

    Reducing costs in terms of time, animal sacrifice, and material resources with computational methods has become a promising goal in Medicinal, Biological, Physical and Organic Chemistry. There are many computational techniques that can be used in this sense. In any case, almost all these methods focus on few fundamental aspects including: type (1) methods to quantify the molecular structure, type (2) methods to link the structure with the biological activity, and others. In particular, MARCH-INSIDE (MI), acronym for Markov Chain Invariants for Networks Simulation and Design, is a well-known method for QSAR analysis useful in step (1). In addition, the bio-inspired Artificial-Intelligence (AI) algorithms called Artificial Neural Networks (ANNs) are among the most powerful type (2) methods. We can combine MI with ANNs in order to seek QSAR models, a strategy which is called herein MIANN (MI & ANN models). One of the first applications of the MIANN strategy was in the development of new QSAR models for drug discovery. MIANN strategy has been expanded to the QSAR study of proteins, protein-drug interactions, and protein-protein interaction networks. In this paper, we review for the first time many interesting aspects of the MIANN strategy including theoretical basis, implementation in web servers, and examples of applications in Medicinal and Biological chemistry. We also report new applications of the MIANN strategy in Medicinal chemistry and the first examples in Physical and Organic Chemistry, as well. In so doing, we developed new MIANN models for several self-assembly physicochemical properties of surfactants and large reaction networks in organic synthesis. In some of the new examples we also present experimental results which were not published up to date.

  2. OBJECT ORIENTED MODELLING, A MODELLING METHOD OF AN ECONOMIC ORGANIZATION ACTIVITY

    Directory of Open Access Journals (Sweden)

    TĂNĂSESCU ANA

    2014-05-01

    Full Text Available Now, most economic organizations use different information systems types in order to facilitate their activity. There are different methodologies, methods and techniques that can be used to design information systems. In this paper, I propose to present the advantages of using the object oriented modelling at the information system design of an economic organization. Thus, I have modelled the activity of a photo studio, using Visual Paradigm for UML as a modelling tool. For this purpose, I have identified the use cases for the analyzed system and I have presented the use case diagram. I have, also, realized the system static and dynamic modelling, through the most known UML diagrams.

  3. 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.

    on the interrelationships of zooplankton and phytoplankton. – Journal of Marine Biological Association U.K 32: 375-445. [2] Brooks, R.R., Presley, B.J., Kaplan, I.R. (1967): APDC-MIBK extraction system for the determination of trace elements in saline waters by Atomic... of contaminants in the food web dynamics as well as in the biogeochemical cycling of trace elements. Zooplanktons are the most abundant animals in the sea, which play an important role in the marine food chain. They mostly feed on phytoplankton and in turn...

  4. Organization And Financing Models Of Health Service In Selected Countries

    Directory of Open Access Journals (Sweden)

    Branimir Marković

    2009-07-01

    Full Text Available The introductory part of the work gives a short theoretical presentation regarding possible financing models of health services in the world. In the applicative part of the work we shall present the basic practical models of financing health services in the countries that are the leaders of classic methods of health services financing, e. g. the USA, Great Britain, Germany and Croatia. Working out the applicative part of the work we gave the greatest significance to analysis of some macroeconomic indicators in health services (tendency of total health consumption in relation to GDP, average consumption per insured person etc., to structure analysis of health insurance and just to the scheme of health service organization and financing. We presume that each model of health service financing contains certain limitations that can cause problem (weak organization, increase of expenses etc.. This is the reason why we, in the applicative part of the work, paid a special attention to analysis of financial difficulties in the health sector and pointed to the needs and possibilities of solving them through possible reform measures. The end part of the work aims to point out to advantages and disadvantages of individual financing sources through the comparison method (budgetary – taxes or social health insurance – contributions.

  5. A neural model of figure-ground organization.

    Science.gov (United States)

    Craft, Edward; Schütze, Hartmut; Niebur, Ernst; von der Heydt, Rüdiger

    2007-06-01

    Psychophysical studies suggest that figure-ground organization is a largely autonomous process that guides--and thus precedes--allocation of attention and object recognition. The discovery of border-ownership representation in single neurons of early visual cortex has confirmed this view. Recent theoretical studies have demonstrated that border-ownership assignment can be modeled as a process of self-organization by lateral interactions within V2 cortex. However, the mechanism proposed relies on propagation of signals through horizontal fibers, which would result in increasing delays of the border-ownership signal with increasing size of the visual stimulus, in contradiction with experimental findings. It also remains unclear how the resulting border-ownership representation would interact with attention mechanisms to guide further processing. Here we present a model of border-ownership coding based on dedicated neural circuits for contour grouping that produce border-ownership assignment and also provide handles for mechanisms of selective attention. The results are consistent with neurophysiological and psychophysical findings. The model makes predictions about the hypothetical grouping circuits and the role of feedback between cortical areas.

  6. Molecular simulation of a model of dissolved organic matter.

    Science.gov (United States)

    Sutton, Rebecca; Sposito, Garrison; Diallo, Mamadou S; Schulten, Hans-Rolf

    2005-08-01

    A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na+ or Ca2+ were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal-humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na+, Ca2+ was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca2+. The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.

  7. Modeling nanostructure-enhanced light trapping in organic solar cells

    DEFF Research Database (Denmark)

    Adam, Jost

    A promising approach for improving the power conversion efficiencies of organic solar cells (OSCs) is by incorporating nanostructures in their thin film architecture to improve the light absorption in the device’s active polymer layers. Here, we present a modelling framework for the prediction...... of optical and plasmonic field enhancement by nanostructures in (or close to) the active layers and electrodes in OSCs. We incorporate finite-difference time-domain (FDTD) calculations alongside semi- analytical approaches, as the rigorous coupled-wave analysis (RCWA) and mode-coupling theory. Our simulation...

  8. Antithrombin III in animal models of sepsis and organ failure.

    Science.gov (United States)

    Dickneite, G

    1998-01-01

    Antithrombin III (AT III) is the physiological inhibitor of thrombin and other serine proteases of the clotting cascade. In the development of sepsis, septic shock and organ failure, the plasma levels of AT III decrease considerably, suggesting the concept of a substitution therapy with the inhibitor. A decrease of AT III plasma levels might also be associated with other pathological disorders like trauma, burns, pancreatitis or preclampsia. Activation of coagulation and consumption of AT III is the consequence of a generalized inflammation called SIRS (systemic inflammatory response syndrome). The clotting cascade is also frequently activated after organ transplantation, especially if organs are grafted between different species (xenotransplantation). During the past years AT III has been investigated in numerous corresponding disease models in different animal species which will be reviewed here. The bulk of evidence suggests, that AT III substitution reduces morbidity and mortality in the diseased animals. While gaining more experience with AT III, the concept of substitution therapy to maximal baseline plasma levels (100%) appears to become insufficient. Evidence from clinical and preclinical studies now suggests to adjust the AT III plasma levels to about 200%, i.e., doubling the normal value. During the last few years several authors proposed that AT III might not only be an anti-thrombotic agent, but to have in addition an anti-inflammatory effect.

  9. A Multiagent Modeling Environment for Simulating Work Practice in Organizations

    Science.gov (United States)

    Sierhuis, Maarten; Clancey, William J.; vanHoof, Ron

    2004-01-01

    In this paper we position Brahms as a tool for simulating organizational processes. Brahms is a modeling and simulation environment for analyzing human work practice, and for using such models to develop intelligent software agents to support the work practice in organizations. Brahms is the result of more than ten years of research at the Institute for Research on Learning (IRL), NYNEX Science & Technology (the former R&D institute of the Baby Bell telephone company in New York, now Verizon), and for the last six years at NASA Ames Research Center, in the Work Systems Design and Evaluation group, part of the Computational Sciences Division (Code IC). Brahms has been used on more than ten modeling and simulation research projects, and recently has been used as a distributed multiagent development environment for developing work practice support tools for human in-situ science exploration on planetary surfaces, in particular a human mission to Mars. Brahms was originally conceived of as a business process modeling and simulation tool that incorporates the social systems of work, by illuminating how formal process flow descriptions relate to people s actual located activities in the workplace. Our research started in the early nineties as a reaction to experiences with work process modeling and simulation . Although an effective tool for convincing management of the potential cost-savings of the newly designed work processes, the modeling and simulation environment was only able to describe work as a normative workflow. However, the social systems, uncovered in work practices studied by the design team played a significant role in how work actually got done-actual lived work. Multi- tasking, informal assistance and circumstantial work interactions could not easily be represented in a tool with a strict workflow modeling paradigm. In response, we began to develop a tool that would have the benefits of work process modeling and simulation, but be distinctively able to

  10. Modeling the role of microplastics in Bioaccumulation of organic chemicals to marine aquatic organisms. Critical Review

    NARCIS (Netherlands)

    Koelmans, A.A.

    2015-01-01

    It has been shown that ingestion of microplastics may increase bioaccumulation of organic chemicals by aquatic organisms. This paper critically reviews the literature on the effects of plastic ingestion on the bioaccumulation of organic chemicals, emphasizing quantitative approaches and mechanistic

  11. Generic Modelling of Faecal Indicator Organism Concentrations in the UK

    Directory of Open Access Journals (Sweden)

    Carl M. Stapleton

    2011-06-01

    Full Text Available To meet European Water Framework Directive requirements, data are needed on faecal indicator organism (FIO concentrations in rivers to enable the more heavily polluted to be targeted for remedial action. Due to the paucity of FIO data for the UK, especially under high-flow hydrograph event conditions, there is an urgent need by the policy community for generic models that can accurately predict FIO concentrations, thus informing integrated catchment management programmes. This paper reports the development of regression models to predict base- and high-flow faecal coliform (FC and enterococci (EN concentrations for 153 monitoring points across 14 UK catchments, using land cover, population (human and livestock density and other variables that may affect FIO source strength, transport and die-off. Statistically significant models were developed for both FC and EN, with greater explained variance achieved in the high-flow models. Both land cover and, in particular, population variables are significant predictors of FIO concentrations, with r2 maxima for EN of 0.571 and 0.624, respectively. It is argued that the resulting models can be applied, with confidence, to other UK catchments, both to predict FIO concentrations in unmonitored watercourses and evaluate the likely impact of different land use/stocking level and human population change scenarios.

  12. LSOT: A Lightweight Self-Organized Trust Model in VANETs

    Directory of Open Access Journals (Sweden)

    Zhiquan Liu

    2016-01-01

    Full Text Available With the advances in automobile industry and wireless communication technology, Vehicular Ad hoc Networks (VANETs have attracted the attention of a large number of researchers. Trust management plays an important role in VANETs. However, it is still at the preliminary stage and the existing trust models cannot entirely conform to the characteristics of VANETs. This work proposes a novel Lightweight Self-Organized Trust (LSOT model which contains trust certificate-based and recommendation-based trust evaluations. Both the supernodes and trusted third parties are not needed in our model. In addition, we comprehensively consider three factor weights to ease the collusion attack in trust certificate-based trust evaluation, and we utilize the testing interaction method to build and maintain the trust network and propose a maximum local trust (MLT algorithm to identify trustworthy recommenders in recommendation-based trust evaluation. Furthermore, a fully distributed VANET scenario is deployed based on the famous Advogato dataset and a series of simulations and analysis are conducted. The results illustrate that our LSOT model significantly outperforms the excellent experience-based trust (EBT and Lightweight Cross-domain Trust (LCT models in terms of evaluation performance and robustness against the collusion attack.

  13. Mukilteo water sensor time series - Field work coupling measurements of carbon chemistry and distribution of free-living organisms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To estimate the carbon chemistry conditions experienced by free-living organisms, we will conduct coupled biological/carbon chemistry sampling for key zooplankton...

  14. Self-Organized Criticality Theory Model of Thermal Sandpile

    International Nuclear Information System (INIS)

    Peng Xiao-Dong; Qu Hong-Peng; Xu Jian-Qiang; Han Zui-Jiao

    2015-01-01

    A self-organized criticality model of a thermal sandpile is formulated for the first time to simulate the dynamic process with interaction between avalanche events on the fast time scale and diffusive transports on the slow time scale. The main characteristics of the model are that both particle and energy avalanches of sand grains are considered simultaneously. Properties of intermittent transport and improved confinement are analyzed in detail. The results imply that the intermittent phenomenon such as blobs in the low confinement mode as well as edge localized modes in the high confinement mode observed in tokamak experiments are not only determined by the edge plasma physics, but also affected by the core plasma dynamics. (paper)

  15. Dynamical quenching and annealing in self-organization multiagent models

    Science.gov (United States)

    Burgos, E.; Ceva, Horacio; Perazzo, R. P.

    2001-07-01

    We study the dynamics of a generalized minority game (GMG) and of the bar attendance model (BAM) in which a number of agents self-organize to match an attendance that is fixed externally as a control parameter. We compare the usual dynamics used for the minority game with one for the BAM that makes a better use of the available information. We study the asymptotic states reached in both frameworks. We show that states that can be assimilated to either thermodynamic equilibrium or quenched configurations can appear in both models, but with different settings. We discuss the relevance of the parameter G that measures the value of the prize for winning in units of the fine for losing. We also provide an annealing protocol by which the quenched configurations of the GMG can progressively be modified to reach an asymptotic equilibrium state that coincides with the one obtained with the BAM.

  16. Modeling financial markets by self-organized criticality

    Science.gov (United States)

    Biondo, Alessio Emanuele; Pluchino, Alessandro; Rapisarda, Andrea

    2015-10-01

    We present a financial market model, characterized by self-organized criticality, that is able to generate endogenously a realistic price dynamics and to reproduce well-known stylized facts. We consider a community of heterogeneous traders, composed by chartists and fundamentalists, and focus on the role of informative pressure on market participants, showing how the spreading of information, based on a realistic imitative behavior, drives contagion and causes market fragility. In this model imitation is not intended as a change in the agent's group of origin, but is referred only to the price formation process. We introduce in the community also a variable number of random traders in order to study their possible beneficial role in stabilizing the market, as found in other studies. Finally, we also suggest some counterintuitive policy strategies able to dampen fluctuations by means of a partial reduction of information.

  17. Models of charge pair generation in organic solar cells.

    Science.gov (United States)

    Few, Sheridan; Frost, Jarvist M; Nelson, Jenny

    2015-01-28

    Efficient charge pair generation is observed in many organic photovoltaic (OPV) heterojunctions, despite nominal electron-hole binding energies which greatly exceed the average thermal energy. Empirically, the efficiency of this process appears to be related to the choice of donor and acceptor materials, the resulting sequence of excited state energy levels and the structure of the interface. In order to establish a suitable physical model for the process, a range of different theoretical studies have addressed the nature and energies of the interfacial states, the energetic profile close to the heterojunction and the dynamics of excited state transitions. In this paper, we review recent developments underpinning the theory of charge pair generation and phenomena, focussing on electronic structure calculations, electrostatic models and approaches to excited state dynamics. We discuss the remaining challenges in achieving a predictive approach to charge generation efficiency.

  18. Partitioning of Nanoparticles into Organic Phases and Model Cells

    Energy Technology Data Exchange (ETDEWEB)

    Posner, J.D.; Westerhoff, P.; Hou, W-C.

    2011-08-25

    There is a recognized need to understand and predict the fate, transport and bioavailability of engineered nanoparticles (ENPs) in aquatic and soil ecosystems. Recent research focuses on either collection of empirical data (e.g., removal of a specific NP through water or soil matrices under variable experimental conditions) or precise NP characterization (e.g. size, degree of aggregation, morphology, zeta potential, purity, surface chemistry, and stability). However, it is almost impossible to transition from these precise measurements to models suitable to assess the NP behavior in the environment with complex and heterogeneous matrices. For decades, the USEPA has developed and applies basic partitioning parameters (e.g., octanol-water partition coefficients) and models (e.g., EPI Suite, ECOSAR) to predict the environmental fate, bioavailability, and toxicity of organic pollutants (e.g., pesticides, hydrocarbons, etc.). In this project we have investigated the hypothesis that NP partition coefficients between water and organic phases (octanol or lipid bilayer) is highly dependent on their physiochemical properties, aggregation, and presence of natural constituents in aquatic environments (salts, natural organic matter), which may impact their partitioning into biological matrices (bioaccumulation) and human exposure (bioavailability) as well as the eventual usage in modeling the fate and bioavailability of ENPs. In this report, we use the terminology "partitioning" to operationally define the fraction of ENPs distributed among different phases. The mechanisms leading to this partitioning probably involve both chemical force interactions (hydrophobic association, hydrogen bonding, ligand exchange, etc.) and physical forces that bring the ENPs in close contact with the phase interfaces (diffusion, electrostatic interactions, mixing turbulence, etc.). Our work focuses on partitioning, but also provides insight into the relative behavior of ENPs as either "more like

  19. The hamster flank organ model: Is it relevant to man

    International Nuclear Information System (INIS)

    Franz, T.J.; Lehman, P.A.; Pochi, P.; Odland, G.F.; Olerud, J.

    1989-01-01

    The critical role that androgens play in the etiology of acne has led to a search for topically active antiandrogens and the frequent use of the flank organ of the golden Syrian hamster as an animal model. 17-alpha-propyltestosterone (17-PT) has been identified as having potent antiandrogenic activity in the hamster model, and this report describes its clinical evaluation. Two double-blind placebo controlled studies comparing 4% 17-PT in 80% alcohol versus vehicle alone were conducted. One study examined 17-PT sebosuppressive activity in 20 subjects. The second study examined its efficacy in 44 subjects having mild to moderate acne. A third study measured in vitro percutaneous absorption of 17-PT through hamster flank and monkey skin, and human face skin in-vivo, using radioactive drug. 17-PT was found to be ineffective in reducing either the sebum excretion rate or the number of inflammatory acne lesions. Failure of 17-PT to show clinical activity was not a result of poor percutaneous absorption. Total absorption in man was 7.7% of the dose and only 1.0% in the hamster. The sebaceous gland of hamster flank organ is apparently more sensitive to antiandrogens than the human sebaceous gland

  20. Modeling temperature dependent singlet exciton dynamics in multilayered organic nanofibers

    Science.gov (United States)

    de Sousa, Leonardo Evaristo; de Oliveira Neto, Pedro Henrique; Kjelstrup-Hansen, Jakob; da Silva Filho, Demétrio Antônio

    2018-05-01

    Organic nanofibers have shown potential for application in optoelectronic devices because of the tunability of their optical properties. These properties are influenced by the electronic structure of the molecules that compose the nanofibers and also by the behavior of the excitons generated in the material. Exciton diffusion by means of Förster resonance energy transfer is responsible, for instance, for the change with temperature of colors in the light emitted by systems composed of different types of nanofibers. To study in detail this mechanism, we model temperature dependent singlet exciton dynamics in multilayered organic nanofibers. By simulating absorption and emission spectra, the possible Förster transitions are identified. Then, a kinetic Monte Carlo model is employed in combination with a genetic algorithm to theoretically reproduce time-resolved photoluminescence measurements for several temperatures. This procedure allows for the obtainment of different information regarding exciton diffusion in such a system, including temperature effects on the Förster transfer efficiency and the activation energy of the Förster mechanism. The method is general and may be employed for different systems where exciton diffusion plays a role.

  1. Use of an Autonomous Surface Vehicle reveals small-scale diel vertical migrations of zooplankton and susceptibility to light pollution under low solar irradiance.

    Science.gov (United States)

    Ludvigsen, Martin; Berge, Jørgen; Geoffroy, Maxime; Cohen, Jonathan H; De La Torre, Pedro R; Nornes, Stein M; Singh, Hanumant; Sørensen, Asgeir J; Daase, Malin; Johnsen, Geir

    2018-01-01

    Light is a major cue for nearly all life on Earth. However, most of our knowledge concerning the importance of light is based on organisms' response to light during daytime, including the dusk and dawn phase. When it is dark, light is most often considered as pollution, with increasing appreciation of its negative ecological effects. Using an Autonomous Surface Vehicle fitted with a hyperspectral irradiance sensor and an acoustic profiler, we detected and quantified the behavior of zooplankton in an unpolluted light environment in the high Arctic polar night and compared the results with that from a light-polluted environment close to our research vessels. First, in environments free of light pollution, the zooplankton community is intimately connected to the ambient light regime and performs synchronized diel vertical migrations in the upper 30 m despite the sun never rising above the horizon. Second, the vast majority of the pelagic community exhibits a strong light-escape response in the presence of artificial light, observed down to 100 m. We conclude that artificial light from traditional sampling platforms affects the zooplankton community to a degree where it is impossible to examine its abundance and natural rhythms within the upper 100 m. This study underscores the need to adjust sampling platforms, particularly in dim-light conditions, to capture relevant physical and biological data for ecological studies. It also highlights a previously unchartered susceptibility to light pollution in a region destined to see significant changes in light climate due to a reduced ice cover and an increased anthropogenic activity.

  2. Zooplankton predators and prey: body size and stable isotope to investigate the pelagic food web in a deep lake (Lake Iseo, Northern Italy

    Directory of Open Access Journals (Sweden)

    Barbara Leoni

    2016-09-01

    Full Text Available Seasonal changes in trophic position and food sources of deep subalpine lake (Lake Iseo, Northern Italy zooplankton taxa were investigated during the year 2011. Furthermore, it's combined carbon and nitrogen Stable Isotope Analysis (SIA with size-specific analyses of both, the major predatory cladoceran (Leptodora kindtii, Focke and two potential preys (Daphnia longispina complex and Eubosmina longicornis. SIA studies have been extremely useful to track the energy flow through complex trophic network, however, if it is applied to analyze relation between two/few species may lead to misleading interpretations. In fact, integrating size-specificity allowed for understanding why L. kindtii nitrogen isotopic fingerprint fully overlapped with Daphnia, in spring. By investigating changes in L. kindtii's feeding basket, we found that in spring, L. kindtii mainly relied upon E. longicornis as prey, Daphnia being of too large body size for being captured by L. kindtii. Among preys encountered directly in front by a free-swimming Leptodora, only those able to fit into basket opening can be captured. As basket diameter increases with animal body length, size selection of prey depends on L. kindtii body length. As in other deep, subalpine lakes, E. longicornis was less 15N-enriched than Daphnia, most likely because of exploiting nitrogen fixing, cyanobacteria colonies, commonly detected in Lake Iseo with the onset of thermal stratification. Cyclopoid adults were at the top of zooplankton food chain and they could potentially be feeding on Daphnia. They, however, likely fed in a different habitat (>20 m deep water, as suggested by a rather than negligible carbon fractionation. The results overall suggest that size-specificity is crucial for addressing space and time changes in trophic links between organisms composing the two hierarchical levels within open water zooplankton community. 

  3. Towards a paradigm shift in the modeling of soil organic carbon decomposition for earth system models

    Science.gov (United States)

    He, Yujie

    Soils are the largest terrestrial carbon pools and contain approximately 2200 Pg of carbon. Thus, the dynamics of soil carbon plays an important role in the global carbon cycle and climate system. Earth System Models are used to project future interactions between terrestrial ecosystem carbon dynamics and climate. However, these models often predict a wide range of soil carbon responses and their formulations have lagged behind recent soil science advances, omitting key biogeochemical mechanisms. In contrast, recent mechanistically-based biogeochemical models that explicitly account for microbial biomass pools and enzyme kinetics that catalyze soil carbon decomposition produce notably different results and provide a closer match to recent observations. However, a systematic evaluation of the advantages and disadvantages of the microbial models and how they differ from empirical, first-order formulations in soil decomposition models for soil organic carbon is still needed. This dissertation consists of a series of model sensitivity and uncertainty analyses and identifies dominant decomposition processes in determining soil organic carbon dynamics. Poorly constrained processes or parameters that require more experimental data integration are also identified. This dissertation also demonstrates the critical role of microbial life-history traits (e.g. microbial dormancy) in the modeling of microbial activity in soil organic matter decomposition models. Finally, this study surveys and synthesizes a number of recently published microbial models and provides suggestions for future microbial model developments.

  4. Disentangling the counteracting effects of water content and carbon mass on zooplankton growth

    DEFF Research Database (Denmark)

    Mcconville, Kristian; Atkinson, Angus; Fileman, Elaine S.

    2017-01-01

    Zooplankton vary widely in carbon percentage (carbon mass as a percentage of wet mass), but are often described as either gelatinous or non-gelatinous. Here we update datasets of carbon percentage and growth rate to investigate whether carbon percentage is a continuous trait, and whether its incl...

  5. Zooplankton resting egg banks in permanent and temporary tropical aquatic systems

    Directory of Open Access Journals (Sweden)

    Luciana Rabelo Araújo

    Full Text Available AIM: We evaluated zooplankton resting egg banks and active communities in five coastal lagoons and in five temporary pools, aiming to compare the active and the dormant communities in such environments. As they differ in hydroperiod, we expected that pools present richer resting egg banks in comparison to those found in lagoons. METHODS: Zooplankton community was sampled twice in 2006 (lagoons and in 2010 (pools and resting egg banks were sampled once in December 2007 (lagoons and in May 2010 (pools. Resting eggs were isolated from the sediment by applying the sugar flotation method. RESULTS: In opposition to our expectation, species richness in the resting egg banks of pools did not differ from those of lagoons. Additionally, no difference was found between the active and the dormant zooplankton communities in each water body for both temporary and permanent environments. However, similarity between active and dormant communities was greater in permanent environments than it was in temporary environments. CONCLUSIONS: It seems that the diapause strategy observed in certain tropical zooplankton populations cannot be predicted based on the awareness of the environment type (permanent or temporary, since hatching cues may be species-specific.

  6. Effects of sandbar openings on the zooplankton community of coastal lagoons with different conservation status

    Directory of Open Access Journals (Sweden)

    Rayanne Barros Setubal

    Full Text Available AIM: Artificial sandbar openings are a common management practice in coastal lagoons but they can be a threat when negative effects to the quality of water and to the aquatic biota are observed. The current study compared sandbar opening effects in two coastal lagoons located close to each other, but differing on trophic status and on sandbar openings' background. METHODS:Limnological variables and zooplankton community were recorded monthly during one year before and one year after sandbar openings that occurred in the same month for both lagoons, giving 24 samples. We compared the effects of sandbar opening on response variables, according to the two types of system. RESULTS: The sandbar openings determined changes in some limnological features - depth and salinity - but such effects were different in the two types of system. The zooplankton structure displayed dramatic changes in the eutrophic and commonly opened lagoon. The occurrence and abundance of some species were closely related to changes in limnological variables. CONCLUSIONS: Our data indicated that zooplankton communities are more resistant to sandbar openings in coastal lagoons historically less disturbed. The direction and magnitude of changes promoted by sandbar openings might be specific to each lagoon, due to different backgrounds of disturbances that, in the long term, modify the water quality and the structure of zooplankton communities, and consequently, their resistance and resilience.

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

    International Nuclear Information System (INIS)

    Lampert, W.; Taylor, B.E.

    1985-01-01

    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 μm) was labeled with 32 P; a larger green alga (Scenedesmus, 4-15 μm) was labeled with 14 C. 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

  8. Rapid reassessment of the eutrophication status of Kingston Harbour, Jamaica using the zooplankton community

    Directory of Open Access Journals (Sweden)

    Patrice A. Francis

    2014-09-01

    Full Text Available Previous extensive studies of zooplankton distribution in the eutrophic Kingston Harbour established that it was being continuously contaminated. We assessed the community in 2011, 17 years after a previous study and five years after the introduction of a tertiary waste water system. Sampling was conducted for four weeks at eight stations identical to those sampled in a previous study. We used horizontal surface tows with a 200µm net. A total of 73 zooplankton taxa were identified and copepods dominated with 20 species. Mean total abundances were high, ranging from a minimum of 2 383 animals m-3 in the southern region of Hunts Bay to 194 166 animals m-3at the Inner Harbour. Five zooplankton taxa (Acartia tonsa, Paracalanus spp., Temora turbinata, Penilia avirostris and Lucifer faxoni that were previously identified as indicators, were again important in the Harbour. The overall zooplankton abundances were similar and in some cases higher than the previous study. There was no significant improvement in the water quality since the introduction of the treatment system at Soapberry. This may be a result of unknown nutrient inputs or of nutrient remaining in the sediments.

  9. Emergent Macrophytes Support Zooplankton in a Shallow Tropical Lake: A Basis for Wetland Conservation

    Science.gov (United States)

    Gebrehiwot, Mesfin; Kifle, Demeke; Triest, Ludwig

    2017-12-01

    Understanding the biodiversity value of littoral zones of lakes is a priority for aquatic biodiversity conservation. However, less emphasis has been given to the littoral part of tropical African lakes, with many of the previous researches focusing only on the open water side. The aim of the present study was, therefore, to investigate the impact of the littoral zone of a shallow freshwater tropical lake (Ziway, Ethiopia), dominated by two emergent macrophytes, on zooplankton community structure. We hypothesized that the wetland vegetation serves as a preferred microhabitat for zooplankton communities. A lake with substantial coverage of emergent macrophytes was monitored monthly from January to August, 2016. The monitoring included the measurements of physical, chemical, and biological parameters. Sampling sites were selected to represent areas of the macrophyte vegetation ( Typha latifolia and Phragmites australis) and the open water part of the lake. Sites with macrophyte vegetation were found to be the home of more dense and diverse zooplankton community. However, during the period of high vegetation loss, the density of crustacean zooplankton showed significant reduction within the patches of macrophytes. From biodiversity conservation perspective, it was concluded that the preservation of such small areas of macrophytes covering the littoral zone of lakes could be as important as protecting the whole lake. However, the rapid degradation of wetland vegetation by human activities is a real threat to the lake ecosystem. In the not-too-far future, it could displace and evict riparian vegetation and the biota it supports.

  10. Zooplankton in littoral waters of a tropical lake: a revisited biodiversity

    Directory of Open Access Journals (Sweden)

    PM. Maia-Barbosa

    Full Text Available The present study was carried out in Lake Dom Helvécio, in the state of Minas Gerais, with two main objectives: to demonstrate the contribution of the littoral zone, in order to better characterize zooplankton fauna; and to assess the distribution of zooplankton species in different habitats, i.e., the littoral zone with and without aquatic vegetation. The samples were collected in February and July 2006, throughout the littoral zone of the lake, in areas with and without aquatic vegetation. We identified a total of 188 species, of which 130 are new records for Lake Dom Helvécio. One hundred and eighty-four species were identified in the littoral zone with aquatic vegetation, and 117 in the zone with no vegetation. The higher zooplankton richness in areas of the littoral zone with aquatic vegetation can be related to the greater environmental heterogeneity. Compared to previous studies on the littoral zones of lakes along the middle River Doce, the present study expended greater sampling effort, and identified many more species. In relation to biological conservation, this study demonstrated the importance of the littoral zone for better characterization and conservation of the zooplankton fauna, especially when it is colonized by aquatic vegetation. Underestimating the richness of species may provide inaccurate data on the biota, as well as on the ecological conditions in an environment.

  11. 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.

    Trace metal (Fe, Co, Ni, Cu, Zn, Cd, and Pb) concentrations in zooplankton from the mixed layer were investigated at 8 coastal and 20 offshore stations in the western Bay of Bengal during the summer monsoon of 2003. The ecotoxicological importance...

  12. Biochemical composition and calorific value of zooplankton from northern part of Central Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

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

    Average biomass value of zooplankton obtained was 22.69 ml 100 m-3. Average percentages of lipid, carbohydrate, protein and carbon were 6.3, 6.0, 23.6 and 34.62 respectively. Calorific values ranged between 6217 and 24708 J.g-1 dry wt (8082...

  13. Zooplankton from the shelf watrs off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Peter, G.

    Zooplankton in the shelf waters of India from Dabhol to Tuticorin was studied during the 17th cruise of R.V. Gaveshani in March 1977. Biomass values were relatively high in the central zone between Mangalore and Alleppey. In the region between...

  14. Zooplankton community structure in the Yellow Sea and East China Sea in autumn

    Directory of Open Access Journals (Sweden)

    Hongju Chen

    2015-12-01

    Full Text Available Abstract Study on zooplankton spatial distribution is essential for understanding food web dynamics in marine ecosystems and fishery management. Here we elucidated the composition and distribution of large mesozooplankton on the continental shelf of the Yellow Sea and East China Sea, and explored the zooplankton community structure in these water masses. Sixty vertical hauls (bottom or 200 m in deep water to surface using a ring net (diameter 0.8 m, 505-μm mesh were exploited in November 2007. The biogeographic patterns of zooplankton communities were investigated using multivariate analysis methods; copepod biodiversity was analyzed using univariate indices. Copepods and protozoans were dominate in the communities. Based on the species composition, we divided the study areas into six station groups. Significant differences in zooplankton assemblages were detected between the Yellow Sea and East China Sea. Species richness was higher in East China Sea groups than those in Yellow Sea, whereas taxonomic distinctness was higher in Yellow Sea than in East China Sea. There was a clear relationship between the species composition and water mass group.

  15. 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.T.; Nair, K.K.C.; Pillai, N.G.K.

    Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September-October, 2003) during the Cruises...

  16. 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.

    content was 0.01 to 0.25 mu g g/1 (dry). Among the various groups of zooplankton studied chaetognaths, bivalve, and crustaceans showed higher rate of bioaccumulation. The distribution of other heavy metals was not abnormal and the values were below...

  17. Mercury, cadmium and lead in different tissues of fishes and in zooplankton from the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Kureishy, T.W.; Sanzgiri, S.; George, M.D.; Braganca, A.

    Several fishes, representing different trophic levels, and some zooplankton samples were analysed for Hg, Cd and Pb There is a wide variation in the concentrations of these elements Hg is quite low in practically all the tissues Cd and Pb show...

  18. Zooplankton incidence in abnormally high sea surface temperature in the Eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.

    Zooplankton in an abnormally high sea surface temperature (33.1 to 33.8 degrees C) and alternate bands of slick formation were studied in the Eastern Arabian Sea during 26 and 29 April 1981. The phenomenon which may be due to intense diurnal heating...

  19. Standing stock and biochemical composition of zooplankton in the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Achuthankutty, C.T.

    function as a reserve food in tropical zooplankton. Lipid, carbohydrate, ash, carbon and calorific content did not show much variation. Standing crop was estimated as 352.13 mgC.m super(2) for the upper 50m column of the coastal region, 716.82 mgC.M super(2...

  20. Improved protocols to accelerate the assembly of DNA barcode reference libraries for freshwater zooplankton.

    Science.gov (United States)

    Elías-Gutiérrez, Manuel; Valdez-Moreno, Martha; Topan, Janet; Young, Monica R; Cohuo-Colli, José Angel

    2018-03-01

    Currently, freshwater zooplankton sampling and identification methodologies have remained virtually unchanged since they were first established in the beginning of the XX century. One major contributing factor to this slow progress is the limited success of modern genetic methodologies, such as DNA barcoding, in several of the main groups. This study demonstrates improved protocols which enable the rapid assessment of most animal taxa inhabiting any freshwater system by combining the use of light traps, careful fixation at low temperatures using ethanol, and zooplankton-specific primers. We DNA-barcoded 2,136 specimens from a diverse array of taxonomic assemblages (rotifers, mollusks, mites, crustaceans, insects, and fishes) from several Canadian and Mexican lakes with an average sequence success rate of 85.3%. In total, 325 Barcode Index Numbers (BINs) were detected with only three BINs (two cladocerans and one copepod) shared between Canada and Mexico, suggesting a much narrower distribution range of freshwater zooplankton than previously thought. This study is the first to broadly explore the metazoan biodiversity of freshwater systems with DNA barcodes to construct a reference library that represents the first step for future programs which aim to monitor ecosystem health, track invasive species, or improve knowledge of the ecology and distribution of freshwater zooplankton.

  1. The role of zooplankton in the feeding ecology of fish fry from some ...

    African Journals Online (AJOL)

    cyclopoid cope pods were the dominant food item of fry < 20 mm S.L., with the ... seas estuarine systems where the diet of fry has been intensively studied (e.g. ..... consumers in oceanic waters but in estuaries benthic herbivores and detritivores ... rine systems is via the zooplankton food chain (Blaber 1979;. Wooldridge ...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat; Wagh

    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 23.43...

  3. 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...

  4. Determine Age-structure of Gelatinous Zooplankton Using Optical Coherence Tomography

    Science.gov (United States)

    Bi, H.; Shahrestani, S.; He, Y.

    2016-02-01

    Gelatinous are delicate and transparent by nature, but are conspicuous in many ecosystems when in bloom. Their proliferations are a bothersome and costly nuisance and influencing important food webs and species interactions. More importantly, gelatinous zooplankton respond to climate change rapidly and understanding their upsurge needs information on their recruitment and population dynamics which in turn require their age-structure. However, ageing gelatinous zooplankton is often restricted by the fact that they shrink under unfavorable conditions. In the present study, we examine the potential of using optical coherence tomography (OCT) to age gelatinous zooplankton. OCT is a non-invasive imaging technique that uses light waves to examine 2D or 3D structure of target objects at a resolution of 3-5 µm. We were able to successfully capture both 3D and 2D images of sea nettle muscle fibers. Preliminary results on ctenophores will be discussed. Overall, this non-destructive sampling allows us to scan and capture images of mesoglea from jellyfish cultured in the lab, using the same individual repeatedly through time, documenting its growth which will provide precise measurements to construct an age key that will be applied to gelatinous zooplankton captured in the field. Coupled with information on abundance, we can start to quantify their recruitment timing and success rate.

  5. Zooplankton standing stock and diversity along an oceanic track in the western Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.

    Zooplankton samples were collected from 13 stations situated in the oceanic realm between latitudes 8 degrees 49 minutes N and 19 degrees 48 minutes S in January-February, 1981. Standing stock varied between 1.6 and 10.4 ml/100 m@u3...

  6. Size-dependent responses of zooplankton to submerged macrophyte restoration in a subtropical shallow lake

    Science.gov (United States)

    Zeng, Lei; He, Feng; Zhang, Yi; Liu, Biyun; Dai, Zhigang; Zhou, Qiaohong; Wu, Zhenbin

    2018-03-01

    To explore the size-dependent responses of zooplankton to submerged macrophyte restoration, we collected macrophyte, zooplankton and water quality samples seasonally from a subtropical shallow lake from 2010 to 2012. Special attention was given to changes in rotifers and crustaceans (cladocerans and copepods). The rotifers were grouped into three size classes (400 μm) to explore their size-related responses to macrophyte restoration. The results showed that during the restoration, the annual mean biomass and macrophyte coverage increased significantly from 0 to 637 g/m2 and 0 to 27%, respectively. In response, the density and biomass of crustaceans and the crustacean-to-rotifer ratio increased significantly, while the rotifer density decreased significantly. Moreover, rotifers showed significant sizedependent responses to macrophyte restoration. Specially, rotifers sized zooplankton tended to boom, while that of small rotifers was inhibited during macrophyte restoration. Redundancy analysis (RDA) revealed positive correlations between macrophytes and crustaceans, rotifers and COD or Chl- a, but negative correlations between macrophytes and COD or Chl- a, and between crustaceans and Chl- a. Moreover, the results indicate that increased predation on phytoplankton by large-sized zooplankton might be an important mechanism for macrophyte restoration during development of aquatic ecosystems, and that this mechanism played a very important role in promoting the formation of a clear-water state in subtropical shallow lakes.

  7. Modeling organic aerosols during MILAGRO: importance of biogenic secondary organic aerosols

    Directory of Open Access Journals (Sweden)

    A. Hodzic

    2009-09-01

    Full Text Available The meso-scale chemistry-transport model CHIMERE is used to assess our understanding of major sources and formation processes leading to a fairly large amount of organic aerosols – OA, including primary OA (POA and secondary OA (SOA – observed in Mexico City during the MILAGRO field project (March 2006. Chemical analyses of submicron aerosols from aerosol mass spectrometers (AMS indicate that organic particles found in the Mexico City basin contain a large fraction of oxygenated organic species (OOA which have strong correspondence with SOA, and that their production actively continues downwind of the city. The SOA formation is modeled here by the one-step oxidation of anthropogenic (i.e. aromatics, alkanes, biogenic (i.e. monoterpenes and isoprene, and biomass-burning SOA precursors and their partitioning into both organic and aqueous phases. Conservative assumptions are made for uncertain parameters to maximize the amount of SOA produced by the model. The near-surface model evaluation shows that predicted OA correlates reasonably well with measurements during the campaign, however it remains a factor of 2 lower than the measured total OA. Fairly good agreement is found between predicted and observed POA within the city suggesting that anthropogenic and biomass burning emissions are reasonably captured. Consistent with previous studies in Mexico City, large discrepancies are encountered for SOA, with a factor of 2–10 model underestimate. When only anthropogenic SOA precursors were considered, the model was able to reproduce within a factor of two the sharp increase in OOA concentrations during the late morning at both urban and near-urban locations but the discrepancy increases rapidly later in the day, consistent with previous results, and is especially obvious when the column-integrated SOA mass is considered instead of the surface concentration. The increase in the missing SOA mass in the afternoon coincides with the sharp drop in POA

  8. Impacts of algal blooms removal by chitosan-modified soils on zooplankton community in Taihu Lake,China

    Institute of Scientific and Technical Information of China (English)

    Jiajia Ni; Yuhe Yu; Weisong Feng; Qingyun Yan; Gang pan; Bo Yang; Xiang Zhang; Xuemei Li

    2010-01-01

    It is important to assess the effect on zooplankton when perform the environmental protection or restoration technology,especially removing algal blooms,because algae were the major primary producer in algal lakes.The influence on zooplankton community after half a year of algal blooms removed by chitosan-modified soils in Taihu Lake was assessed and the rationality of carrying out the process semiannually was evaluated in the present study.Morphological composition and genetic diversity of zooplankton community were investigated by microscope checkup and polymerase chain reaction-denatured gradient gel electrophoresis (PCR-DGGE).A total of 44 zooplankton taxa (23 protozoa,17 rotifers,3 copepoda and 1 cladocera) were detected by microscope checkup,and a total of 91 bands (28 bands amplified by primers F1427-GC and R1616,63 bands amplified by primers Fung-G-C and NS1) were detected by PCR-DGGE.The results of cluster analysis or detrended correspondence analysis indicated that there was no considerable difference in morphological composition of zooplankton and DGGE profiles between experimental and control sites,and DGGE profiles could represent the biologic diversity.The study showed that zooplankton community could recover original condition after half year of algal blooms removed by chitosan-modified soils and it was acceptable to apply this process semiannually.In addition,the results revealed that PCR-DGGE could be applied to investigate the impacts of the environmental protection or restoration engineering on zooplankton community diversity.

  9. Spatial patterns of littoral zooplankton assemblages along a salinity gradient in a brackish sea: A functional diversity perspective

    Science.gov (United States)

    Helenius, Laura K.; Leskinen, Elina; Lehtonen, Hannu; Nurminen, Leena

    2017-11-01

    The distribution patterns and diversity of littoral zooplankton are both key baseline information for understanding the functioning of coastal ecosystems, and for identifying the mechanisms by which the impacts of recently increased eutrophication are transferred through littoral food webs. In this study, zooplankton community structure and diversity along a shallow coastal area of the northern Baltic Sea were determined in terms of horizontal environmental gradients. Spatial heterogeneity of the zooplankton community was examined along the gradient. Altogether 31 sites in shallow sandy bays on the coast of southwest Finland were sampled in the summer periods of 2009 and 2010 for zooplankton and environmental variables (surface water temperature, salinity, turbidity, wave exposure, macrophyte coverage, chlorophyll a and nutrients). Zooplankton diversity was measured as both taxonomic as well as functional diversity, using trait-based classification of planktonic crustaceans. Salinity, and to a lesser extent turbidity and temperature, were found to be the main predictors of the spatial patterns and functional diversity of the zooplankton community. Occurrence of cyclopoid copepods, as well as abundances of the calanoid copepod genus Acartia and the rotifer genus Keratella were found to be key factors in differentiating sites along the gradient. As far as we know, this is the first extensive study of functional diversity in Baltic Sea coastal zooplankton communities.

  10. Article Review: Lessepsian migration of zooplankton through Suez Canal and its impact on ecological system

    Directory of Open Access Journals (Sweden)

    Howaida Y. Zakaria

    2015-01-01

    Full Text Available The marine environment of the East Mediterranean has been considerably impacted in modern times by two man-made changes: the creation of a waterway between the Indo-Pacific and the Mediterranean basins and the control of the Nile fresh-water outflow. The opening of the Suez Canal caused a migration generally from the Red Sea to the Mediterranean, and rarely in the opposite direction as the Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrient-poor eastern Mediterranean. Accordingly Red Sea species invaded the Mediterranean ecosystem and not vice versa; this phenomenon is known as the Lessepsian migration or erythrean invasion. The composition of zooplankton in the eastern Mediterranean has been shown to include a large proportion of Indo-Pacific and other circumtropical species which have successfully settled and proliferated in this environment. During the present study, an overview is provided on zooplankton migration through Suez Canal and its impact on the ecological system based on published literature. It is also meant with the hydrographic and zooplankton characteristics of the adjacent seas. It is clear that, except jellyfish Rhopilema nomadica, the negative impact of zooplankton Lessepsian migratory species in the Egyptian Mediterranean waters is not evident. Finally, it would be concluded that, a continuous monitoring programme will be needed to record the recent erythrean zooplankton species and follow up the distribution and abundance of those previously recorded as aliens to assess their impacts on the native biodiversity of the Mediterranean.

  11. Analysis of southeast Australian zooplankton observations of 1938-42 using synoptic oceanographic conditions

    Science.gov (United States)

    Baird, Mark E.; Everett, Jason D.; Suthers, Iain M.

    2011-03-01

    The research vessel Warreen obtained 1742 planktonic samples along the continental shelf and slope of southeast Australia from 1938-42, representing the earliest spatially and temporally resolved zooplankton data from Australian marine waters. In this paper, Warreen observations along the southeast Australian seaboard from 28°S to 38°S are interpreted based on synoptic meteorological and oceanographic conditions and ocean climatologies. Meteorological conditions are based on the NOAA-CIRES 20th Century Reanalysis Project; oceanographic conditions use Warreen hydrological observations, and the ocean climatology is the CSIRO Atlas of Regional Seas. The Warreen observations were undertaken in waters on average 0.45 °C cooler than the climatological average, and included the longest duration El Niño of the 20th century. In northern New South Wales (NSW), week time-scale events dominate zooplankton response. In August 1940 an unusual winter upwelling event occurred in northern NSW driven by a stronger than average East Australian Current (EAC) and anomalous northerly winds that resulted in high salp and larvacean abundance. In January 1941 a strong upwelling event between 28° and 33°S resulted in a filament of upwelled water being advected south and alongshore, which was low in zooplankton biovolume. In southern NSW a seasonal cycle in physical and planktonic characteristics is observed. In January 1941 the poleward extension of the EAC was strong, advecting more tropical tunicate species southward. Zooplankton abundance and distribution on the continental shelf and slope are more dependent on weekly to monthly timescales on local oceanographic and meteorological conditions than continental-scale interannual trends. The interpretation of historical zooplankton observations of the waters off southeast Australia for the purpose of quantifying anthropogenic impacts will be improved with the use of regional hindcasts of synoptic ocean and atmospheric weather that can

  12. Zooplankton communities in three adjacent softwater lobelia lakes of slightly differentiated morphology and trophic state

    Directory of Open Access Journals (Sweden)

    Kuczyńska-Kippen Natalia

    2017-12-01

    Full Text Available The paper presents the results of an investigation of physical-chemical features of water as well as rotifer and crustacean abundance and diversity measures, relating to the taxonomic richness and species diversity index, in three lobelia lakes differing in trophic status and morphometric features. The main purpose of this study was to establish the diversity of zooplankton communities in the open water area of lobelia lakes, including extracting species common for each lake and also to find environmental predictors which are responsible for the development of zooplankton communities. Despite the fact that the three studied lakes are of the same origin, located in the same vicinity and have generally similar environmental factors, zooplankton community structure revealed a great variation in reference to species diversity (only ca. 20% of the species were common for all lakes and particularly in inhabiting species. Obrowo Lake had the most diverse assemblages of both rotifers and crustaceans compared to Modre and Pomysko lakes. In the taxonomic structure species that are rare for the Polish fauna, such as e.g. Holopedium gibberum and Heterocope appendiculata, occurred. Even though the examined lobelia lakes are ecosystems that undergo varying human-induced impacts, they still remain taxonomically very variable aquatic ecosystems, containing rare species of very high ecological status. The observed symptoms of deterioration of water quality, reflected in the zooplankton biocoenotic features, showed that the best conditions were attributed to Obrowo Lake in comparison with the two remaining lakes – Modre and Pomysko. Total nitrogen and chlorophyll a concentration were decisive for the distribution of zooplankton species in Pomysko and Obrowo lakes, while in case of Modre lake water reactivity and conductivity were of higher impact.

  13. Nephrology around Europe: organization models and management strategies: Spain.

    Science.gov (United States)

    de Francisco, Angel L M; Piñera, Celestino

    2011-01-01

    The main aim of this report is to present a picture of the current organization of nephrology in Spain. The Spanish health system offers almost universal coverage, a wide variety of services and a high-quality network of hospitals and primary care centers. Spain has a specialized health care training system that is highly developed, highly regulated, with the capacity to provide high-quality training in 54 different specialties. Nephrology is basically a hospital-based specialty. There are no private dialysis patients in Spain. Hemodialysis centers are 40% public, 15% private and 45% run by companies. The National Health System covers 95% of the population, and there is no cost to patients for treatment of renal disease (dialysis and transplant). We observed a clear decrease of nephrology in residents' election rankings, with position 29 out of 47 specialties in 2007. Some of the reasons for this are the complexity of the subject, no clear information at the university, reduction of professional posts and a very good public service with minimal private practice. In Spain, a model of organization for transplantation was adopted based on a decentralized transplant coordinating network. For cadaveric donors, it compares favorably with rates in other Western countries. Living donor transplantation is very low in Spain--just 10% of total renal transplantation activity. New programs due to financial constraints need to include reduced dialysis costs, greater cost-effectiveness of prescriptions, better handling of ethical issues related to the need for using a clinical score of chronic kidney disease patients to make decisions about conservative or renal replacement therapy and an action plan for improvement of organ donation and transplantation. Recovery of skills (acute kidney injury, biopsies, vascular access, etc.), research and advances in autonomous activities (imaging, surgical and medical vascular training, etc.) are some of the future educational paths needed in

  14. Stratigraphic modeling of organic matter distribution and preservation in deep marine environment. Case of a margin with pelagic sedimentation: the coastal upwelling system of Benguela (Namibia, Western South Africa); Modelisation stratigraphique de la distribution et de la preservation de la matiere organique en milieu marin profond. Cas d'une marge a sedimentation pelagique: systeme d'upwelling cotier du Benguela (Namibie, Afrique du Sud Ouest)

    Energy Technology Data Exchange (ETDEWEB)

    Tranier, J.

    2006-06-15

    In order to develop stratigraphic modelling of organic matter distribution and preservation in marine environment, the methodology established, uses three modelling softwares. We make use of a 3D stratigraphic model, DIONISOS, which allows to build margin thanks to sediment input and transport and thanks to basin deformation. Biogenic sediments are introduced in DIONISOS after their production modelling by two coupled models, ROMS and NPZD. ROMS is a physical model which allows to simulate upwelling dynamics thanks to wind strength exerted on ocean surface and to margin morphology. NPZD models relationships (photosynthesis, grazing, excretion, mortality, re-mineralization, etc.) between four boxes: nutrients, phytoplankton, zooplankton and detritus. Nutrients availability (model inputs) and flux intensity between boxes are controlled by upwelling dynamics, i-e ROMS. Thanks to these three softwares, organic matter can be modelled from its production to its fossilization considering the influence of various factors as upwelling intensity, nutrients availability, chemical compounds of water mass and oxygenation of water column, species competition (diatoms and coccolithophoridae), margin morphology and eustatism. After testing sensibility of the various parameters of the three models, we study their capacity for reproduce biogenic sedimentation and simulate climatic cycle effect on organic matter distribution on a passive continental margin: the Namibian margin (Southwest Africa). They are validated comparing results with core data from this margin. (author)

  15. Modeling evolutionary dynamics of epigenetic mutations in hierarchically organized tumors.

    Directory of Open Access Journals (Sweden)

    Andrea Sottoriva

    2011-05-01

    Full Text Available The cancer stem cell (CSC concept is a highly debated topic in cancer research. While experimental evidence in favor of the cancer stem cell theory is apparently abundant, the results are often criticized as being difficult to interpret. An important reason for this is that most experimental data that support this model rely on transplantation studies. In this study we use a novel cellular Potts model to elucidate the dynamics of established malignancies that are driven by a small subset of CSCs. Our results demonstrate that epigenetic mutations that occur during mitosis display highly altered dynamics in CSC-driven malignancies compared to a classical, non-hierarchical model of growth. In particular, the heterogeneity observed in CSC-driven tumors is considerably higher. We speculate that this feature could be used in combination with epigenetic (methylation sequencing studies of human malignancies to prove or refute the CSC hypothesis in established tumors without the need for transplantation. Moreover our tumor growth simulations indicate that CSC-driven tumors display evolutionary features that can be considered beneficial during tumor progression. Besides an increased heterogeneity they also exhibit properties that allow the escape of clones from local fitness peaks. This leads to more aggressive phenotypes in the long run and makes the neoplasm more adaptable to stringent selective forces such as cancer treatment. Indeed when therapy is applied the clone landscape of the regrown tumor is more aggressive with respect to the primary tumor, whereas the classical model demonstrated similar patterns before and after therapy. Understanding these often counter-intuitive fundamental properties of (non-hierarchically organized malignancies is a crucial step in validating the CSC concept as well as providing insight into the therapeutical consequences of this model.

  16. A geometrical model for DNA organization in bacteria.

    Directory of Open Access Journals (Sweden)

    Mathias Buenemann

    Full Text Available Recent experimental studies have revealed that bacteria, such as C. crescentus, show a remarkable spatial ordering of their chromosome. A strong linear correlation has been found between the position of genes on the chromosomal map and their spatial position in the cellular volume. We show that this correlation can be explained by a purely geometrical model. Namely, self-avoidance of DNA, specific positioning of one or few DNA loci (such as origin or terminus together with the action of DNA compaction proteins (that organize the chromosome into topological domains are sufficient to get a linear arrangement of the chromosome along the cell axis. We develop a Monte-Carlo method that allows us to test our model numerically and to analyze the dependence of the spatial ordering on various physiologically relevant parameters. We show that the proposed geometrical ordering mechanism is robust and universal (i.e. does not depend on specific bacterial details. The geometrical mechanism should work in all bacteria that have compacted chromosomes with spatially fixed regions. We use our model to make specific and experimentally testable predictions about the spatial arrangement of the chromosome in mutants of C. crescentus and the growth-stage dependent ordering in E. coli.

  17. Modeling cooperating micro-organisms in antibiotic environment.

    Science.gov (United States)

    Book, Gilad; Ingham, Colin; Ariel, Gil

    2017-01-01

    Recent experiments with the bacteria Paenibacillus vortex reveal a remarkable strategy enabling it to cope with antibiotics by cooperating with a different bacterium-Escherichia coli. While P. vortex is a highly effective swarmer, it is sensitive to the antibiotic ampicillin. On the other hand, E. coli can degrade ampicillin but is non-motile when grown on high agar percentages. The two bacterial species form a shared colony in which E. coli is transported by P. vortex and E. coli detoxifies the ampicillin. The paper presents a simplified model, consisting of coupled reaction-diffusion equations, describing the development of ring patterns in the shared colony. Our results demonstrate some of the possible cooperative movement strategies bacteria utilize in order to survive harsh conditions. In addition, we explore the behavior of mixed colonies under new conditions such as antibiotic gradients, synchronization between colonies and possible dynamics of a 3-species system including P. vortex, E. coli and a carbon producing algae that provides nutrients under illuminated, nutrient poor conditions. The derived model was able to simulate an asymmetric relationship between two or three micro-organisms where cooperation is required for survival. Computationally, in order to avoid numerical artifacts due to symmetries within the discretizing grid, the model was solved using a second order Vectorizable Random Lattices method, which is developed as a finite volume scheme on a random grid.

  18. Modeling cooperating micro-organisms in antibiotic environment.

    Directory of Open Access Journals (Sweden)

    Gilad Book

    Full Text Available Recent experiments with the bacteria Paenibacillus vortex reveal a remarkable strategy enabling it to cope with antibiotics by cooperating with a different bacterium-Escherichia coli. While P. vortex is a highly effective swarmer, it is sensitive to the antibiotic ampicillin. On the other hand, E. coli can degrade ampicillin but is non-motile when grown on high agar percentages. The two bacterial species form a shared colony in which E. coli is transported by P. vortex and E. coli detoxifies the ampicillin. The paper presents a simplified model, consisting of coupled reaction-diffusion equations, describing the development of ring patterns in the shared colony. Our results demonstrate some of the possible cooperative movement strategies bacteria utilize in order to survive harsh conditions. In addition, we explore the behavior of mixed colonies under new conditions such as antibiotic gradients, synchronization between colonies and possible dynamics of a 3-species system including P. vortex, E. coli and a carbon producing algae that provides nutrients under illuminated, nutrient poor conditions. The derived model was able to simulate an asymmetric relationship between two or three micro-organisms where cooperation is required for survival. Computationally, in order to avoid numerical artifacts due to symmetries within the discretizing grid, the model was solved using a second order Vectorizable Random Lattices method, which is developed as a finite volume scheme on a random grid.

  19. Spectrophotometry and organic matter on Iapetus. 1: Composition models

    Science.gov (United States)

    Wilson, Peter D.; Sagan, Carl

    1995-01-01

    Iapetus shows a greater hemispheric albedo asymmetry than any other body in the solar system. Hapke scattering theory and optical constants measured in the laboratory are used to identify possible compositions for the dark material on the leading hemisphere of Iapetus. The materials considered are poly-HCN, kerogen, Murchison organic residue, Titan tholin, ice tholin, and water ice. Three-component mixtures of these materials are modeled in intraparticle mixture of 25% poly-HCN, 10% Murchison residue, and 65% water ice is found to best fit the spectrum, albedo, and phase behavior of the dark material. The Murchison residue and/or water ice can be replaced by kerogen and ice tholin, respectively, and still produce very good fits. Areal and particle mixtures of poly-HCN, Titan tholin, and either ice tholin or Murchison residue are also possible models. Poly-HCN is a necessary component in almost all good models. The presence of poly-HCN can be further tested by high-resolution observations near 4.5 micrometers.

  20. Self-Organized Criticality in an Anisotropic Earthquake Model

    Science.gov (United States)

    Li, Bin-Quan; Wang, Sheng-Jun

    2018-03-01

    We have made an extensive numerical study of a modified model proposed by Olami, Feder, and Christensen to describe earthquake behavior. Two situations were considered in this paper. One situation is that the energy of the unstable site is redistributed to its nearest neighbors randomly not averagely and keeps itself to zero. The other situation is that the energy of the unstable site is redistributed to its nearest neighbors randomly and keeps some energy for itself instead of reset to zero. Different boundary conditions were considered as well. By analyzing the distribution of earthquake sizes, we found that self-organized criticality can be excited only in the conservative case or the approximate conservative case in the above situations. Some evidence indicated that the critical exponent of both above situations and the original OFC model tend to the same result in the conservative case. The only difference is that the avalanche size in the original model is bigger. This result may be closer to the real world, after all, every crust plate size is different. Supported by National Natural Science Foundation of China under Grant Nos. 11675096 and 11305098, the Fundamental Research Funds for the Central Universities under Grant No. GK201702001, FPALAB-SNNU under Grant No. 16QNGG007, and Interdisciplinary Incubation Project of SNU under Grant No. 5

  1. In Vivo RNAi-Based Screens: Studies in Model Organisms

    Directory of Open Access Journals (Sweden)

    Miki Yamamoto-Hino

    2013-11-01

    Full Text Available RNA interference (RNAi is a technique widely used for gene silencing in organisms and cultured cells, and depends on sequence homology between double-stranded RNA (dsRNA and target mRNA molecules. Numerous cell-based genome-wide screens have successfully identified novel genes involved in various biological processes, including signal transduction, cell viability/death, and cell morphology. However, cell-based screens cannot address cellular processes such as development, behavior, and immunity. Drosophila and Caenorhabditis elegans are two model organisms whose whole bodies and individual body parts have been subjected to RNAi-based genome-wide screening. Moreover, Drosophila RNAi allows the manipulation of gene function in a spatiotemporal manner when it is implemented using the Gal4/UAS system. Using this inducible RNAi technique, various large-scale screens have been performed in Drosophila, demonstrating that the method is straightforward and valuable. However, accumulated results reveal that the results of RNAi-based screens have relatively high levels of error, such as false positives and negatives. Here, we review in vivo RNAi screens in Drosophila and the methods that could be used to remove ambiguity from screening results.

  2. Modified FlowCAM procedure for quantifying size distribution of zooplankton with sample recycling capacity.

    Directory of Open Access Journals (Sweden)

    Esther Wong

    Full Text Available We have developed a modified FlowCAM procedure for efficiently quantifying the size distribution of zooplankton. The modified method offers the following new features: 1 prevents animals from settling and clogging with constant bubbling in the sample container; 2 prevents damage to sample animals and facilitates recycling by replacing the built-in peristaltic pump with an external syringe pump, in order to generate negative pressure, creates a steady flow by drawing air from the receiving conical flask (i.e. vacuum pump, and transfers plankton from the sample container toward the main flowcell of the imaging system and finally into the receiving flask; 3 aligns samples in advance of imaging and prevents clogging with an additional flowcell placed ahead of the main flowcell. These modifications were designed to overcome the difficulties applying the standard FlowCAM procedure to studies where the number of individuals per sample is small, and since the FlowCAM can only image a subset of a sample. Our effective recycling procedure allows users to pass the same sample through the FlowCAM many times (i.e. bootstrapping the sample in order to generate a good size distribution. Although more advanced FlowCAM models are equipped with syringe pump and Field of View (FOV flowcells which can image all particles passing through the flow field; we note that these advanced setups are very expensive, offer limited syringe and flowcell sizes, and do not guarantee recycling. In contrast, our modifications are inexpensive and flexible. Finally, we compared the biovolumes estimated by automated FlowCAM image analysis versus conventional manual measurements, and found that the size of an individual zooplankter can be estimated by the FlowCAM image system after ground truthing.

  3. Two stressors and a community - Effects of hydrological disturbance and a toxicant on freshwater zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Stampfli, Nathalie C. [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Quantitative Landscape Ecology, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau (Germany); Knillmann, Saskia [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Department of Ecosystem Analyses, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Liess, Matthias [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Noskov, Yury A. [Institute of Systematics and Ecology of Animals, Russian Academy of Sciences, Siberian Branch, Frunze St. 11, 630091 Novosibirsk (Russian Federation); Schaefer, Ralf B. [Quantitative Landscape Ecology, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau (Germany); Beketov, Mikhail A., E-mail: mikhail.beketov@ufz.de [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany)

    2013-02-15

    Climate change models predict an increase in the frequency and intensity of extreme fluctuations in water level in aquatic habitats. Therefore, it is necessary to understand the combined effects of hydrological fluctuations and toxicants on aquatic biological communities. We investigated the individual and combined effects of the insecticide esfenvalerate and recurring fluctuations in water level on zooplankton communities in a system of 55 outdoor pond microcosms. The communities were exposed to esfenvalerate contamination as a single pulse (at 0.03, 0.3, or 3 {mu}g/L) and gradual removal of water and its subsequent replacement over three cycles and monitored until 84 days after contamination. The results showed that the sensitivities of the community and its constituent populations to the toxicant were increased by the hydrological stress. Specifically, for both the community structure and abundance of Daphnia spp. the lowest-observed-effect concentrations (LOEC) were 0.03 and 0.3 {mu}g/L for the series with fluctuating and constant water levels, respectively. Despite these differences in sensitivity, the interactive effects of the two stressors were found to be additive for both the community structure and the abundance of the most affected species. Presumably, it was not possible to detect synergism due to the strong individual effects of the water level fluctuations. Recovery times in the series exposed to the highest pesticide concentration were 64 and 55 days under fluctuating and constant water level regimes, respectively. Competition and water quality are suggested to be the major factors that underlie the observed effects of fluctuations in the water level. For the ecological risk assessment of toxicants, the present results suggest that (i) community sensitivity may vary substantially, depending on the environmental context, and (ii) this variability can be assessed experimentally to derive safety factors (coefficients used to avoid unexpected effects

  4. Azolla--a model organism for plant genomic studies.

    Science.gov (United States)

    Qiu, Yin-Long; Yu, Jun

    2003-02-01

    The aquatic ferns of the genus Azolla are nitrogen-fixing plants that have great potentials in agricultural production and environmental conservation. Azolla in many aspects is qualified to serve as a model organism for genomic studies because of its importance in agriculture, its unique position in plant evolution, its symbiotic relationship with the N2-fixing cyanobacterium, Anabaena azollae, and its moderate-sized genome. The goals of this genome project are not only to understand the biology of the Azolla genome to promote its applications in biological research and agriculture practice but also to gain critical insights about evolution of plant genomes. Together with the strategic and technical improvement as well as cost reduction of DNA sequencing, the deciphering of their genetic code is imminent.

  5. Giant plasma membrane vesicles: models for understanding membrane organization.

    Science.gov (United States)

    Levental, Kandice R; Levental, Ilya

    2015-01-01

    The organization of eukaryotic membranes into functional domains continues to fascinate and puzzle cell biologists and biophysicists. The lipid raft hypothesis proposes that collective lipid interactions compartmentalize the membrane into coexisting liquid domains that are central to membrane physiology. This hypothesis has proven controversial because such structures cannot be directly visualized in live cells by light microscopy. The recent observations of liquid-liquid phase separation in biological membranes are an important validation of the raft hypothesis and enable application of the experimental toolbox of membrane physics to a biologically complex phase-separated membrane. This review addresses the role of giant plasma membrane vesicles (GPMVs) in refining the raft hypothesis and expands on the application of GPMVs as an experimental model to answer some of key outstanding problems in membrane biology. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Corporate Social Responsibility And Islamic Business Organizations: A Proposed Model

    Directory of Open Access Journals (Sweden)

    Rusnah Muhamad

    2008-01-01

    Full Text Available The issue of corporate social responsibility (CSR has been of growing concern among business communities in recent years. Various corporate leaders maintain that business is considered to contribute fully to the society if it is effi cient, profi table and socially responsible. Islam is considered as addin (a way of life, thus, providing comprehensive guidelines in every aspects of the believers’ life. It is the aim of this paper to propose an Islamic model of corporate social responsibility based on human relationships with the God (hablun min’Allah; with other fellow human being (hablun min’an-nas and with the environment.Keywords : Corporate Social Responsibility, Islamic Business Organization

  7. A NEW ORGANIZATIONAL FORM: STARFISH ORGANIZATION IN BUSINESS MODEL PERSPECTIVE

    OpenAIRE

    Aygul Turan; Aysegul Ozbebek Tunc

    2013-01-01

    As we moved into new economy, decentralization is a very powerful strategy day by day. A large number of traditional organizations are decentralized- some of them decentralize a part of the organization, some of them decentralize whole of the organizations- because of being a winner of the competition. As a decentralized organization, starfish organization is a new concept of the organizational science literature. In this framework, we focus on the starfish organization’s structure. The aim o...

  8. Regulation of Mnemiopsis leidyi dynamics by potential changes in temperature and zooplankton conditions in the Black Sea.

    Science.gov (United States)

    Salihoglu, B.; Fach, B.; Oguz, T.

    2009-04-01

    Providing a comprehensive understanding of the effects that cause formations of ctenophore blooms in the Black Sea is the main objective of this study. In order to analyse ctenophore dynamics in the Black Sea a zero-dimensional population based model of the ctenophore Mnemiopsis leidyi is developed. The stage resolving ctenophore model combines the modified form of stage resolving approach of Fennel, 2001 with the growth dynamics model of Kremer, 1976; Kremer and Reeve, 1989 under 4 stages of model-ctenophore. These stages include the different growth characteristics of egg, juvenile, transitional and adult stages. The dietary patterns of the different stages follows the observations obtained from the literature. The model is able to represent consistent development patterns, while reflecting the physiological complexity of a population of Mnemiopsis leidyi. Model results suggest that different nutritional requirement of each stage may serve as the bottlenecks for population growth and only when growth conditions are favorable for both larval and lobate stages, the high overall population growth rates may occur. Model is also used to analyse the influence of climatic changes on Mnemiopsis leidyi reproduction and outburst. This study presents and discussed how potential changes in temperature and zooplankton conditions in the Black Sea may regulate Mnemiopsis leidyi dynamics.

  9. Modeling Organic Contaminant Desorption from Municipal Solid Waste Components

    Science.gov (United States)

    Knappe, D. R.; Wu, B.; Barlaz, M. A.

    2002-12-01

    Approximately 25% of the sites on the National Priority List (NPL) of Superfund are municipal landfills that accepted hazardous waste. Unlined landfills typically result in groundwater contamination, and priority pollutants such as alkylbenzenes are often present. To select cost-effective risk management alternatives, better information on factors controlling the fate of hydrophobic organic contaminants (HOCs) in landfills is required. The objectives of this study were (1) to investigate the effects of HOC aging time, anaerobic sorbent decomposition, and leachate composition on HOC desorption rates, and (2) to simulate HOC desorption rates from polymers and biopolymer composites with suitable diffusion models. Experiments were conducted with individual components of municipal solid waste (MSW) including polyvinyl chloride (PVC), high-density polyethylene (HDPE), newsprint, office paper, and model food and yard waste (rabbit food). Each of the biopolymer composites (office paper, newsprint, rabbit food) was tested in both fresh and anaerobically decomposed form. To determine the effects of aging on alkylbenzene desorption rates, batch desorption tests were performed after sorbents were exposed to toluene for 30 and 250 days in flame-sealed ampules. Desorption tests showed that alkylbenzene desorption rates varied greatly among MSW components (PVC slowest, fresh rabbit food and newsprint fastest). Furthermore, desorption rates decreased as aging time increased. A single-parameter polymer diffusion model successfully described PVC and HDPE desorption data, but it failed to simulate desorption rate data for biopolymer composites. For biopolymer composites, a three-parameter biphasic polymer diffusion model was employed, which successfully simulated both the initial rapid and the subsequent slow desorption of toluene. Toluene desorption rates from MSW mixtures were predicted for typical MSW compositions in the years 1960 and 1997. For the older MSW mixture, which had a

  10. Toxicity of noradrenaline, a novel anti-biofouling component, to two non-target zooplankton species, Daphnia magna and Ceriodaphnia dubia.

    Science.gov (United States)

    Overturf, C L; Wormington, A M; Blythe, K N; Gohad, N V; Mount, A S; Roberts, A P

    2015-05-01

    Noradrenaline (NA) is the active component of novel antifouling agents and acts by preventing attachment of fouling organisms. The goal of this study was to examine the toxicity of NA to the non-target zooplankton D. magna and C. dubia. Neonates were exposed to one of five concentrations of NA and effects on survival, reproduction and molting were determined. Calculated LC50 values were determined to be 46 and 38 μM in C. dubia and D. magna, respectively. A 10-day C. dubia study found that reproduction metrics were significantly impacted at non-lethal concentrations. In D. magna, concentrations greater than 40 μM significantly impacted molting. A toxicity test was conducted with D. magna using oxidized NA, which yielded similar results. These data indicate that both NA and oxidized NA are toxic to non-target zooplankton. Results obtained from this study can be used to guide future ecological risk assessments of catecholamine-based antifouling agents. Copyright © 2015. Published by Elsevier Inc.

  11. Development of a statistical shape model of multi-organ and its performance evaluation

    International Nuclear Information System (INIS)

    Nakada, Misaki; Shimizu, Akinobu; Kobatake, Hidefumi; Nawano, Shigeru

    2010-01-01

    Existing statistical shape modeling methods for an organ can not take into account the correlation between neighboring organs. This study focuses on a level set distribution model and proposes two modeling methods for multiple organs that can take into account the correlation between neighboring organs. The first method combines level set functions of multiple organs into a vector. Subsequently it analyses the distribution of the vectors of a training dataset by a principal component analysis and builds a multiple statistical shape model. Second method constructs a statistical shape model for each organ independently and assembles component scores of different organs in a training dataset so as to generate a vector. It analyses the distribution of the vectors of to build a statistical shape model of multiple organs. This paper shows results of applying the proposed methods trained by 15 abdominal CT volumes to unknown 8 CT volumes. (author)

  12. Elimination kinetic model for organic chemicals in earthworms.

    NARCIS (Netherlands)

    Dimitrova, N.; Dimitrov, S.; Georgieva, D.; van Gestel, C.A.M.; Hankard, P.; Spurgeon, D.J.; Li, H.; Mekenyan, O.

    2010-01-01

    Mechanistic understanding of bioaccumulation in different organisms and environments should take into account the influence of organism and chemical depending factors on the uptake and elimination kinetics of chemicals. Lipophilicity, metabolism, sorption (bioavailability) and biodegradation of

  13. KICS: A Model of Motivational Leadership in Organizations

    Directory of Open Access Journals (Sweden)

    John N. N. Ugoani

    2015-09-01

    Full Text Available This pure research gave birth to a Model of Motivational Leadership – KICS: which embraces knowledge, intelligence, collaboration and synergy. It is a synergistic  proposition based on the theory of emotional intelligence as the index of competencies needed for effective leadership. It opened with a general discussion on traditional models of leadership, then the roles of knowledge, intelligence, collaboration and synergy as they relate to motivational leadership. Issues of emotional intelligence clusters and synthesis of the model’s elements were discussed, emphasizing how KICS-based motivational leadership skills can be developed and sustained. Motivational leadership entails exciting people’s imaginations and inspiring them to move in a desired direction. It takes more than simple power to motivate and lead in organizations. Realizing that unity and cohesiveness are built from personal bonds, the best leaders ensure to deepen their rapport with employees and colleagues which enhances organizational performance. This pure research argues that the synergy of related emotional intelligence competencies can lead to motivational leadership behaviour. Knowledge is critical to leadership because there are different types of leadership and different situations require different kinds of knowledge, and the person possessing the knowledge demanded by a certain situation in most cases, tends to become the best leader. A knowledgeable person is one who is trained to consider his actions to undertake them deliberately, in a disciplined manner. Added to this ability is the intelligence to endure in a chosen course in the face of distraction, confusion and difficulty, all combined in producing a motivational leader. Knowledge tends to be procedural in nature and to operate outside of focal awareness. It also reflects the structure of the situation more closely than it does in the structure of formal disciplinary knowledge. The survey research design

  14. Comparison of Mercury in Water, Bottom Sediment, and Zooplankton in Two Front Range Reservoirs in Colorado, 2008-09

    Science.gov (United States)

    Mast, M. Alisa; Krabbenhoft, David P.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the Colorado Department of Public Health and Environment, conducted a study to investigate environmental factors that may contribute to the bioaccumulation of mercury in two Front Range reservoirs. One of the reservoirs, Brush Hollow Reservoir, currently (2009) has a fish-consumption advisory for mercury in walleye (Stizostedion vitreum), and the other, Pueblo Reservoir, which is nearby, does not. Water, bottom sediment, and zooplankton samples were collected during 2008 and 2009, and a sediment-incubation experiment was conducted in 2009. Total mercury concentrations were low in midlake water samples and were not substantially different between the two reservoirs. The only water samples with detectable methylmercury were collected in shallow areas of Brush Hollow Reservoir during spring. Mercury concentrations in reservoir bottom sediments were similar to those reported for stream sediments from unmined basins across the United States. Despite higher concentrations of fish-tissue mercury in Brush Hollow Reservoir, concentrations of methylmercury in sediment were as much as 3 times higher in Pueblo Reservoir. Mercury concentrations in zooplankton were at the low end of concentrations reported for temperate lakes in the Northeastern United States and were similar between sites, which may reflect the seasonal timing of sampling. Factors affecting bioaccumulation of mercury were assessed, including mercury sources, water quality, and reservoir characteristics. Atmospheric deposition was determined to be the dominant source of mercury; however, due to the proximity of the reservoirs, atmospheric inputs likely are similar in both study areas. Water-quality constituents commonly associated with elevated concentrations of mercury in fish (pH, alkalinity, sulfate, nutrients, and dissolved organic carbon) did not appear to explain differences in fish-tissue mercury concentrations between the reservoirs. Low methylmercury

  15. Concentrations of 137Cs and trace elements in zooplankton, and their vertical distributions off Rokkasho, Japan

    International Nuclear Information System (INIS)

    Kaeriyama, Hideki; Ishii, Toshiaki; Watabe, Teruhisa; Kusakabe, Masashi

    2007-01-01

    Zooplankton samples were collected at about 50 m depth with a large ring net (160-cm mouth diameter, 0.5-mm mesh) in May, June, October 2005 and June 2006 off Rokkasho, Japan where a nuclear fuel reprocessing plant will be in full-scale operation in the near future. Plankters in each sample were separated based on their species. Eight samples were used for the determination of 137 Cs concentration and the other 21 samples were used for the determination of its stable isotope, Cs along with some other trace elements. All the samples were characterized by five dominant species, i.e. euphausiids, chaetognaths, copepods; Neocalanus spp., amphipods; Themisto spp. and Cyphocaris sp. Plankton samples were also taken at three to five discrete depths between the surface and ≤ 1,000 m in depth during daytime and nighttime for analysis of vertical distribution patterns of biomass, and for assessment of daily vertical migration activity. Integrated net zooplankton biomass at nighttime ranged from 0.85 to 8.74 g-DW m -2 in the 0-150 m layer without any appreciable day-night differences in the vertical distribution; below the layer, it decreased significantly. Only in spring, appreciable day-night differences in the vertical distribution were observed at the shallowest station. Concentrations of Cs and Co did not show significant difference among the five species. However, higher concentrations of Sr were observed in two amphipods. It is likely that amphipods had a different biological process in Sr metabolism from others. The concentration of 137 Cs in zooplankton was usually very low and sometimes under the detection limit. In the present study, the highest concentration of 137 Cs in zooplankton was 24 mBq kg-WW -1 , corresponding to the concentration factor (CF) of 14, if the value of 1.7 mBq L -1 was given to the 137 Cs concentration in seawater. The water-column inventory of 137 Cs in a zooplankton community is calculated to be 0.29 to 1.95 mBq m -2 , based on the data on

  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.

    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...

  17. Blooms of phytoplankton along the west coast of India associated with nutrient enrichment and the response of zooplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, S.R.S.; Devassy, V.P.; Madhupratap, M.

    and dinoflagellates are also common Spectacular bloom formations of Trichodesmium is a regular phenomenon during the later part of the NE monsoon season At times, these blooms cover hundreds of kilometres Very often successions of phyto- and zooplankton communities...

  18. Zooplankton Structure and Potential Food Web Interactions in the Plankton of a Subtropical Chain-of-Lakes

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2002-01-01

    Full Text Available This study evaluates the taxonomic and size structure of macro-zooplankton and its potential role in controlling phytoplankton in the Kissimmee Chain-of-Lakes, six shallow interconnected lakes in Florida, U.S. Macro-zooplankton species biomass and standard limnological attributes (temperature, pH, total phosphorus [TP], chlorophyll a [Chl a], and Secchi transparency were quantified on a bimonthly basis from April 1997 to February 1999. Concentrations of TP ranged from below 50 to over 150 μg l-1. Peak concentrations of particulate P coincided with maximal Chl a, and in one instance a high concentration of soluble reactive P followed. The cladoceran zooplankton was dominated by small species, including Eubosmina tubicen, Ceriodaphnia rigaudi, and Daphnia ambigua. The exotic daphnid, D. lumholtzii, periodically was abundant. The copepods were strongly dominated by Diaptomus dorsalis, a species previously shown to be highly resistant to fish predation. These results, and findings of controlled experiments on a nearby lake with a nearly identical zooplankton species complement, suggest that fish predation may be a major factor structuring the macro-zooplankton assemblage. Zooplankton biomass, on the other hand, may be affected by resource availability. There was a significant positive relationship between average biomass of macro-zooplankton and the average concentration of TP among the six lakes. No such relationship existed between zooplankton biomass and Chl a, suggesting that the predominant food web in these systems may be based on bacteria-plankton, as has been documented in nearby Lake Okeechobee. All of the zooplankton taxa encountered in the Kissimmee Chain-of-Lakes (except Mesocyclops edax are known bacteria grazers in Florida lakes. Phytoplankton biomass, measured as Chl a, was strongly associated with TP, both within and across lakes. Phytoplankton biomass was not associated with the biomass of zooplankton. These results, when

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    Sigrid B. Schnack-Schiel

    2005-12-01

    Full Text Available 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, where particle fluxes close to the sea floor beyond the continental shelf break do not normally show seasonal variation within shallow environments. Commonly, at depths shallower than 500 m, the most evident feature is that more than 90% of the annual fluxes occur during a short period of the spring-summer. This event is masked near the seabed at greater depths due to resupension and lateral advection of particles. Faecal material of various origins is one of the main constituents of the biogenic matter flux. It usually reaches its maximum in February once the early phytoplankton bloom has developed. However, the presence of faecal pellets is ubiquitous during the months of the year when there is enough light to support primary production. At this stage more research is needed to elucidate the particular role of distinct taxa—including among others salps, krill, copepods and protozoans—in the transport of organic matter to the benthos, and their contribution to the biogeochemical cycles of carbon, nitrogen, phosphorus and silicon. Aggregation of particles is another important process controlling the development and dynamics of pelagic-benthic coupling due to its influence on the sinking velocity of particles and the enhancement of organic matter utilisation by members of the microbial loop in the upper layers of the water column. Also in shallow waters, aggregation favours the transfer of high-quality organic matter to the benthic realm. At greater