Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Seabirds, gyres and global trends in plastic pollution
    Franeker, J.A. van; Law, K.L. - \ 2015
    Environmental Pollution 203 (2015). - ISSN 0269-7491 - p. 89 - 96.
    fulmars fulmarus-glacialis - northern fulmars - particle pollution - marine-environment - surface waters - south-atlantic - ingestion - debris - ocean - sea
    Fulmars are effective biological indicators of the abundance of floating plastic marine debris. Long-term data reveal high plastic abundance in the southern North Sea, gradually decreasing to the north at increasing distance from population centres, with lowest levels in high-arctic waters. Since the 1980s, pre-production plastic pellets in North Sea fulmars have decreased by ~75%, while user plastics varied without a strong overall change. Similar trends were found in net-collected floating plastic debris in the North Atlantic subtropical gyre, with a ~75% decrease in plastic pellets and no obvious trend in user plastic. The decreases in pellets suggest that changes in litter input are rapidly visible in the environment not only close to presumed sources, but also far from land. Floating plastic debris is rapidly “lost” from the ocean surface to other as-yet undetermined sinks in the marine environment.
    Elevated levels of ingested plastic in a high Arctic seabird, the northern fulmar (Fulmarus glacialis)
    Trevail, A.M. ; Gabrielsen, G.W. ; Kühn, S. ; Franeker, J.A. van - \ 2015
    Polar Biology 38 (2015)7. - ISSN 0722-4060 - p. 975 - 981.
    atlantic-ocean - sea - debris - biodiversity - pacific - chicks
    Plastic pollution is of worldwide concern; however, increases in international commercial activity in the Arctic are occurring without the knowledge of the existing threat posed to the local marine environment by plastic litter. Here, we quantify plastic ingestion by northern fulmars, Fulmarus glacialis, from Svalbard, at the gateway to future shipping routes in the high Arctic. Plastic ingestion by Svalbard fulmars does not follow the established decreasing trend away from human marine impact. Of 40 sampled individuals, 35 fulmars (87.5 %) had plastic in their stomachs, averaging at 0.08 g or 15.3 pieces per individual. Plastic ingestion levels on Svalbard exceed the ecological quality objective defined by OSPAR for European seas. This highlights an urgent need for mitigation of plastic pollution in the Arctic as well as international regulation of future commercial activity.
    Seasonal Variation of Fatty Acids and Stable Carbon Isotopes in Sponges as Indicators for Nutrition: Biomarkers in Sponges Identified
    Koopmans, M. ; Rijswijk, P. van; Boschker, H.T.S. ; Houtekamer, M. ; Martens, D.E. ; Wijffels, R.H. - \ 2015
    Marine Biotechnology 17 (2015)1. - ISSN 1436-2228 - p. 43 - 54.
    marine organisms - halichondria-panicea - lipids - sea - demospongiae - community - bacteria
    To get a better understanding of sponge feeding biology and efficiencies, the fatty acid (FA) composition and 13C natural abundance of sponges and of suspended particulate matter (SPM) from surrounding seawater was studied in different seasons at three locations. Haliclona oculata and Haliclona xena from the Oosterschelde, the Netherlands, Halichondria panicea and H. xena from Lake Veere, the Netherlands, and Aplysina aerophoba and Dysidea avara from the Mediterranean, Spain, were studied. Several FA biomarkers for different algal groups, bacteria and sponge biomass were identified in all sponges. The FA concentration variation in sponges was related to changes in fatty acid concentration in SPM. Stable carbon isotopic ratios (d13C) in sponge specific FAs showed very limited seasonal variation at all sites. Algal FAs in sponges were mainly acquired from the SPM through active filtration in all seasons. At the two sites in the Netherlands only in May (spring), the sponge specific FAs had similar d13C ratios as algal FAs, suggesting that sponges were mainly growing during spring and probably summer. During autumn and winter, they were still actively filtering, but the food collected during this period had little effect on sponge d13C values suggesting limited incorporation of filtered material into the sponge body. The sponge A. aerophoba relied mostly on the symbiotic bacteria. In conclusion, fatty acid composition in combination with stable carbon isotope analysis can be used to analyze the food source of sponges.
    Quirky patterns in time-series of estimates of recruitment could be artefacts
    Dickey-Collas, M. ; Hintzen, N.T. ; Nash, R.D.M. ; Schoen, P.J. ; Payne, M.R. - \ 2015
    ICES Journal of Marine Science 72 (2015)1. - ISSN 1054-3139 - p. 111 - 116.
    stock-assessment - marine fishes - assessment models - reference points - atlantic - variability - abundance - sea - populations - management
    The accessibility of databases of global or regional stock assessment outputs is leading to an increase in meta-analysis of the dynamics of fish stocks. In most of these analyses, each of the time-series is generally assumed to be directly comparable. However, the approach to stock assessment employed, and the associated modelling assumptions, can have an important influence on the characteristics of each time-series. We explore this idea by investigating recruitment time-series with three different recruitment parameterizations: a stock–recruitment model, a random-walk time-series model, and non-parametric “free” estimation of recruitment. We show that the recruitment time-series is sensitive to model assumptions and this can impact reference points in management, the perception of variability in recruitment and thus undermine meta-analyses. The assumption of the direct comparability of recruitment time-series in databases is therefore not consistent across or within species and stocks. Caution is therefore required as perhaps the characteristics of the time-series of stock dynamics may be determined by the model used to generate them, rather than underlying ecological phenomena. This is especially true when information about cohort abundance is noisy or lacking.
    Characteristics of the fifth paleosol complex (S-5) in the southernmost part of the Chinese Loess Plateau and its paleo-environmental significance
    Huang, C.Q. ; Tan, W.F. ; Wang, M.K. ; Koopal, L.K. - \ 2014
    Catena 122 (2014). - ISSN 0341-8162 - p. 130 - 139.
    asian monsoon evolution - late quaternary - deposits - soils - sea
    The most prominent paleosol unit in the Chinese Loess Plateau (CLP) is the fifth paleosol complex (S-5) with its well-developed very thick and dark colored pedons. To provide more insight in the formation of S-5 and its environmental significance, the pedogenesis and clay mineral transformation in the S-5 of the Wugong section (Shaanxi Province) on the southernmost CLP are analyzed. S-5 at the Wugong section is essentially composed of three well-developed reddish pedons (i.e., S5-1, S5-2, S5-3) which signify three glacial-interglacial climatic fluctuations during its formation. Complete decalcification in each pedon and a calcic horizon of only 30-50 cm in thickness beneath each of the three pedons suggests that after deposition the pedons developed with a relatively stable surface in a sustained warm and humid climate. Clay formation in the S-5 includes neogenesis of clay materials by in situ post-depositional weathering and mechanical migration of the fine fraction after complete decalcification. Complete leaching of CaCO3, intensive clay formation (with 60-100% higher clay content than that in the overlying and underlying loess (L-5 and L-6)) and extremely high magnetic susceptibility in the S-5 pedons reflected a warmer, more humid climate and soil environment for pedogenesis than in the 'optimum' Holocene. However, the chemical alteration of the phyllosilicate minerals was weak and restrained by the hard calcic horizon, the compact argillic horizon and the flat terrain. The major clay mineral weathering processes during the formation of the S-5 pedons at the Wugong section were depotassication, hydrolysis of primary minerals and degradation of chlorite. The pedogenesis in a loess-paleosol sequence and its pedogenic environment can best be deduced from combined data on pedogenic properties, and geochemical and mineralogical characteristics. (c) 2014 Elsevier B.V. All rights reserved.
    HyMeX, a 10-year multidisciplinary program on the Mediterranean water cycle
    Drobinski, P. ; Ducrocq, V.P. ; Alpert, P. ; Anagnostou, A. ; Béranger, K. ; Borga, M. ; Braud, I. ; Chanzy, A. ; Davolio, S. ; Delrieu, G. ; Estournel, C. ; Filali Boubrahmi, N. ; Uijlenhoet, R. ; Font, J. ; Grubisic, V. ; Gualdi, S. ; Homar, V. ; Ivancan-Picek, B. ; Kottmeier, C. ; Kotroni, V. ; Lagouvardos, K. ; Lionello, P. ; Llasat, M.C. ; Ludwig, W. ; Lutoff, C. ; Mariotti, A. ; Richard, E. ; Romero, R. ; Rotunno, R. ; Roussot, O. ; Ruin, I. ; Somot, S. ; Taupier-Letage, L. ; Tintore, J. ; Wernli, H. - \ 2014
    Bulletin of the American Meteorological Society 95 (2014)7. - ISSN 0003-0007 - p. 1063 - 1082.
    regional climate model - flash-flood - synoptic climatology - deep convection - september 2002 - north-western - precipitation - events - sea - database
    The Mediterranean countries are experiencing important challenges related to the water cycle, including water shortages and floods, extreme winds, and ice/snow storms, that impact critically the socioeconomic vitality in the area (causing damage to property, threatening lives, affecting the energy and transportation sectors, etc.). There are gaps in our understanding of the Mediterranean water cycle and its dynamics that include the variability of the Mediterranean Sea water budget and its feedback on the variability of the continental precipitation through air–sea interactions, the impact of precipitation variability on aquifer recharge, river discharge, and soil water content and vegetation characteristics specific to the Mediterranean basin and the mechanisms that control the location and intensity of heavy precipitating systems that often produce floods. The Hydrological Cycle in Mediterranean Experiment (HyMeX) program is a 10-yr concerted experimental effort at the international level that aims to advance the scientific knowledge of the water cycle variability in all compartments (land, sea, and atmosphere) and at various time and spatial scales. It also aims to improve the processes-based models needed for forecasting hydrometeorological extremes and the models of the regional climate system for predicting regional climate variability and evolution. Finally, it aims to assess the social and economic vulnerability to hydrometeorological natural hazards in the Mediterranean and the adaptation capacity of the territories and populations therein to provide support to policy makers to cope with water-related problems under the influence of climate change, by linking scientific outcomes with related policy requirements.
    Microbial community dynamics in a submerged fixed bed bioreactor during biological treatment of saline urban wastewater
    Cortés-Lorenzo, C. ; Sipkema, D. ; Rodríguez-Díaz, M. ; Fuentes, S. ; Juárez-Jiménez, B. ; Rodelas, B. ; Smidt, H. ; González-López, J. - \ 2014
    Ecological Engineering 71 (2014). - ISSN 0925-8574 - p. 126 - 132.
    activated-sludge - treatment plants - bacterial diversity - sewage-treatment - biofilm reactor - gradient - denitrification - sea
    The influence of salt (NaCl) on bacterial and archaeal communities in a submerged fixed bed bioreactor system for the treatment of urban wastewater was determined by DGGE and 454 pyrosequencing of PCR-amplified 16S ribosomal RNA gene fragments. Cluster analysis of DGGE fingerprints showed significant differences in the community structure dependent on the salt concentration in the influent. Proteobacteria was found to be the dominant bacterial phylum in all experiments, with a-Proteobacteria being the main order at low salinity and ¿-Proteobacteria the dominant order at high salinity. Euryarchaeota was the main archaeal phylum in all experiments, with all microorganisms corresponding to methanogenic archaea. Whereas bacterial a-diversity decreased as salinity increased, archaeal a-diversity increased with higher NaCl concentrations.
    Use it or lose it: measuring trends in wild species subject to substantial use
    Tierney, M. ; Almond, R. ; Stanwell-Smith, D. ; McRae, L. ; Zöckler, C. ; Collen, B. ; Walpole, M. ; Hutton, J. ; Bie, S. de - \ 2014
    Oryx 48 (2014)03. - ISSN 0030-6053 - p. 420 - 429.
    living planet index - extinction risk - biodiversity - populations - management - conservation - sustainability - birds - sea
    The unsustainable use of wild animals and plants is thought to be a significant driver of biodiversity loss in many regions of the world. The international community has therefore called for action to ensure the sustainable use of living resources and safeguard them for future generations. Indicators that can track changes in populations of species used by humans are essential tools for measuring progress towards these ideals and informing management decisions. Here we present two indicators that could be used to track changes in populations of utilized vertebrate species and levels of harvest sustainability. Preliminary results based on sample data both at the global level and for the Arctic show that utilized species are faring better than other species overall. This could be a consequence of better management of these populations, as indicated by more sustainable harvest levels in recent decades. Limitations of the indicators are still apparent; in particular, there is a lack of data on harvested populations of some vertebrate classes and from certain regions. Focusing monitoring efforts on broadening the scope of data collected and identifying interactions with other potential drivers of decline will strengthen these indicators as policy tools and improve their potential to be incorporated into future sets of indicators to track progress towards global biodiversity targets.
    On solving a bi-level stohastic dynamic programming model for analyzing fisheries policies: Fishermen behavior and optimal fish quota
    Dijk, D. van; Hendrix, E.M.T. ; Haijema, R. ; Groeneveld, R.A. ; Ierland, E.C. van - \ 2014
    Ecological Modelling 272 (2014). - ISSN 0304-3800 - p. 68 - 75.
    bioeconomic model - game-theory - management - uncertainty - adjustment - resource - growth - sea
    Stochastic dynamic programming (SDP) is a useful tool for analyzing policy questions in fisheries management. In order to understand and reproduce solution procedures such as value function iteration, an analytic elaboration of the problem and model characteristics is required. Because of the increased use of numerical techniques, our aim is to improve the understanding of mathematical properties of the solution procedure and to give more insight into their practical implementation by means of a specific case that uses value function iteration. We provide an analytic description of model characteristics and analyze the solution procedure of a bi-level SDP model to study fisheries policies. At the first level, a policy maker decides on the fish quota to be imposed, keeping in mind fish stock dynamics, capital stock dynamics, long-term resource rents and anticipating fishermen behavior. At the second level, fishermen reveal short-term behavior by reacting on this quota and on current states of fish stock and capital stock by deciding on their investments and fishing effort. An analysis of the behavior of the model is given and a method is elaborated to obtain optimum strategies based on value function iteration. Bi-level decision making enables us to present the model in an understandable manner, and serves as a basis for extension to more complex settings.
    Application of non-linear quantile regression to macrozoobenthic species distribution modelling: comparing two contrasting basins
    Cozzoli, F. ; Bouma, T.J. ; Ysebaert, T. ; Herman, P.M.J. - \ 2013
    Marine Ecology Progress Series 475 (2013). - ISSN 0171-8630 - p. 119 - 133.
    macrobenthic communities - estuarine gradients - logistic-regression - sediment - inference - selection - splines - sea - environment - habitats
    The occurrence and distribution of macrozoobenthos in estuaries are strongly related to sediment grain-size characteristics. However, statistical prediction of the distribution of benthic populations as a response to a single environmental gradient has proven to be difficult, because the focal variable may set upper limits to the abundance, but other (partly uncorrelated) variables may cause considerable deviation from the maximum. A multi-quantile regression approach is better suited to characterize biota–environment relationships than a single (average or boundary) estimation, because it shows the variation in responses and quantifies the relative importance of other unmeasured factors. Here, a univariate application of non-linear quantile regression is proposed to account for heteroskedasticity and non-linearity in the biological response to sediment grain size. The analysis was applied to a large macrozoobenthic dataset from the SW Delta area (The Netherlands) to compare the relationships between sediment granulometry and macrozoobenthos in 2 neighboring but differing temperate coastal ecosystems (Oosterschelde and Westerschelde). Preference of individual species for grain size was consistent between both systems, although in general, a slightly higher median grain size (ca. +60% in grain diameter) was preferred in the Oosterschelde than in the Westerschelde. The major difference in the community was, however, that mud-preferring species dominated the assemblage in the Westerschelde, and sand-preferring species dominated the Oosterschelde. Although the prevalence of muddy and sandy sediments in both systems is similar, in the Westerschelde, strong hydrodynamic stress is correlated with sandy habitats, causing impoverishment of assemblages at sandy sites. In the Oosterschelde, sandy sediments are usually associated with much more benign conditions and have the richest species assemblage.
    Influence of temperature and food availability on juvenile European anchovy Engraulis encrasicolus at its northern boundary
    Raab, K.E. ; Llope, M. ; Nagelkerke, L.A.J. ; Rijnsdorp, A.D. ; Teal, L.R. ; Licandro, P. ; Ruardij, P. ; Dickey-Collas, M. - \ 2013
    Marine Ecology Progress Series 488 (2013). - ISSN 0171-8630 - p. 233 - 245.
    growth-selective predation - climate-change - sea - bay - energy - biscay - fish - japonicus - life - variability
    The European anchovy Engraulis encrasicolus population of the North Sea has increased and spread in recent decades, probably in response to the relaxation of limiting factors in its life history. We use models and empirical data to explore the effects of temperature and food availability during the first growing season on the adult anchovy population across the North Sea. First, we compare simulated growth during summer and autumn, from a dynamic energy budget model, with trends in the time series of anchovy survey catch per unit effort. The proportion of the area of the North Sea in which anchovy can grow to 10 cm (the potential growth habitat) correlates with the abundance of anchovy caught in surveys the following year. Second, spatio-temporal statistical modeling is used to show that anchovy abundance in surveys is related to environmental variables (temperature and food availability). Temperature explains the distribution and abundance of anchovy in the North Sea better than food availability or a combination of both environmental factors. We conclude that variations in growth during the first months of life can impact anchovy life cycle closure. Specifically for the North Sea anchovy, changes in temperature are more important than changes in food availability in allowing the fish to grow to overwintering size, under probably non-food-limited conditions.
    Connectivity between Migrating and Landlocked Populations of a Diadromous fish Species Investigated Using Otolith Microchemistry
    Tulp, I.Y.M. ; Keller, A.M. ; Navez, J. ; Winter, H.V. ; Graaf, M. de; Baeyens, W. - \ 2013
    PLoS ONE 8 (2013)7. - ISSN 1932-6203
    lake ijsselmeer - netherlands - patterns - water - sea
    Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium (88Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population.
    Marine monitoring in the European Union: How to fulfill the requirements for the marine strategy framework directive in an efficient and integrated way
    Zampoukas, N. ; Piha, H. ; Bigagli, E. ; Hoepffner, N. ; Hanke, G. ; Cardoso, A.C. - \ 2013
    Marine Policy 39 (2013). - ISSN 0308-597X - p. 349 - 351.
    waters - sea
    The Marine Strategy Framework Directive requires from European Union Member States to establish by 2014 ecological monitoring programmes covering all their marine waters and therefore extend existing monitoring and include additional elements. Principles of integrated monitoring and large scale approaches discussed in this communication could contribute to effective and cost efficient programmes
    Foraging black-browed albatrosses target waters overlaying moraine banks-a consequence of upward benthic-pelagic coupling?
    Wakefield, E.D. ; Phillips, R.A. ; Belchier, M. ; Aarts, G. ; Mackenzie, M. ; McConnell, B.J. - \ 2012
    Antarctic Science 24 (2012)3. - ISSN 0954-1020 - p. 269 - 280.
    south-georgia - shag rocks - shelf - segregation - seabirds - ocean - diet - sea - chrysostoma - strategies
    Wide-ranging, surface-feeding pelagic seabirds are the most numerous functional group of birds in the Southern Ocean. The mesoscale habitat use of these birds is increasingly being quantified by relating their movements to remotely sensed, near surface properties of the ocean. However, prey availability at the sea surface may also be determined by habitat characteristics not measurable from space. For instance, benthic-pelagic coupling, which occurs when seabed processes affect productivity in the epipelagic zone, can link benthic habitat type to availability of surface prey. We combined acoustically derived maps of the substrate of the South Georgia shelf with GPS tracking to quantify the sub-mesoscale habitat use of breeding black-browed albatrosses. We show that albatrosses preferentially used waters overlaying glacial moraine banks near the shelf edge and that this was unrelated to the presence of trawlers targeting mackerel icefish, which are also associated with these features. Stomach temperature profiles suggest that albatrosses primarily caught krill and fish over the banks.We hypothesize that black-browed albatrosses target waters overlaying moraine banks due to upward benthic-pelagic coupling, mediated by an increase in abundance of zooplankton such as Antarctic krill. Our findings suggest that the potential effects of such processes on pelagic seabird distribution warrant wider investigation.
    Effect of additional charging and current density on the performance of Capacitive energy extraction based on Donnan Potential
    Liu, F. ; Schaetzle, O. ; Sales, B.B. ; Saakes, M. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Energy & Environmental Science 5 (2012)9. - ISSN 1754-5692 - p. 8642 - 8650.
    pressure retarded osmosis - water salinity difference - reverse electrodialysis - power-generation - gradient power - river water - sea
    The difference in the salt concentrations of river and seawater implies that wherever they mix, energy could be extracted from the salinity gradient. This is a renewable and clean means of generating energy that makes use of a natural process. Capacitive energy extraction based on the Donnan potential (CDP) is a promising technique for extracting this energy. We herein describe our investigation of the effect of additional charging on extraction behaviour using a forced current density. The study was conducted in a flow-through cell, using capacitive electrodes and ion exchange membranes. It is shown that increasing the accumulated charge in the system could be beneficial in terms of energy extraction. Furthermore, the addition of charge improved the power densities achieved. By charging at higher current densities and discharging at lower current densities, the performance of the system may be improved. The highest average power density achieved in this study was 0.205 +/- 0.006 W m(-2) (1.26 +/- 0.75 mW g(-1)). This was obtained using a charge of 6 C (4.62 C g(-1)), with a controlled constant current of 50 mA (38.5 mA g(-1) or 6.24 A m(-2)). Three main limiting factors to the performance of CDP were identified, namely (i) the voltage drop over time, caused by the self-discharge of the cell and the non-ideal behaviour of the membranes, (ii) the duration of the switching times and (iii) the loss over the internal resistance. Of these, the internal resistance was identified as being the most important parameter to be minimized in order to further improve the performances of CDP systems.
    Faster Time Response by the Use of Wire Electrodes in Capacitive Salinity Gradient Energy Systems
    Burheim, O.S. ; Liu, F. ; Sales, B.B. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 116 (2012)36. - ISSN 1932-7447 - p. 19203 - 19210.
    pressure-retarded osmosis - reverse electrodialysis - power - extraction - water - sea - performance - density
    Capacitive energy extraction based on Donnan potential (CDP) and capacitive energy extraction based on double layer expansion (CDLE) are novel electroctrochemical processes to convert the potential free energy of mixing sea and river water into electric work. This is done by the use of supercapacitor electrodes with and without ion exchange membranes. Currently, these techniques rely on improved mass transport in order to become more efficient and give higher power output. In this paper we evaluate the transport phenomena by diffusion and the electrode geometry when switching between sea and river water at open circuit potential (OCP). By changing the electrode geometry from a flat plate to a cylindrical one, experiments and analytical models in combination show that mass transport by diffusion is increased. This is demonstrated without any changes in the hydrodynamic conditions. Improving mass transport without changing the hydrodynamic conditions breaks with what has been the convention in the scientific community of salinity gradient power. Moreover, in sea water the transport phenomena appear to be controlled by diffusion, and the response time for building open circuit potential in CDP and CDLE under this condition is reduced by a factor of 2 when using wire electrodes instead of flat plate electrodes. In river water, the trend is similar though the response time is generally larger.
    Impact of Wire Geometry in Energy Extraction from Salinity Differences Using Capacitive Technology
    Sales, B.B. ; Burheim, O.S. ; Liu, F. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Environmental Science and Technology 46 (2012)21. - ISSN 0013-936X - p. 12203 - 12208.
    pressure retarded osmosis - reverse electrodialysis - water desalination - renewable energy - power production - river water - electrodes - sea - deionization - gradients
    Energy extraction based on capacitive Donnan potential (CDP) is a recently suggested technique for sustainable power generation. CDP combines the use of ion-exchange membranes and porous carbon electrodes to convert the Gibbs free energy of mixing sea and river water into electric work. The electrodes geometry has a relevant impact on internal resistance and overall performance in CDP. In this work, we present the first effort to use wire shaped electrodes and its suitability for improving CDP. Analytical evaluation and electrical measurements confirm a strong nonlinear decrease in internal resistance for distances between electrodes smaller than 3 mm. We also demonstrated that we get more power per material invested when compared to traditional flat plate designs. These findings show the advantages of this design for further development of CDP into a mature technology.
    Electrochemical characterization of a supercapacitor flow cell for power production from salinity gradients
    Sales, B.B. ; Liu, F. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Electrochimica Acta 86 (2012). - ISSN 0013-4686 - p. 298 - 304.
    energy - electrodes - water - sea
    Salinity gradients could be a great source of energy in the future. Capacitive energy extraction based on Donnan Potential (CDP) is a new technique to directly convert this energy into electricity. COP uses a supercapacitor-like device combining ion exchange membranes and capacitive materials to adsorb and desorb ions with the Donnan Potential of the membranes as only driving force. The resulting current can be extracted through an external load. In this study, traditional electrochemical techniques: galvanostatic charge-discharge and cyclic voltammetry were used to investigate intrinsic properties of this open system. This study demonstrates the feasibility to characterize the capacitive behavior of the cell in low concentration (0.5 M). Presence of membranes, as well as the possibility of having the electrolyte flowing through the cell was investigated. In the studied cell, the presence of membranes showed a limitation by the anion exchange membrane at low current densities but no effect at high current densities. The flow rate did not influence the capacitance of the system either.
    Implications of using alternative methods of vessel monitoring system (VMS) data analysis to describe fishing activities and impacts
    Lambert, G.I. ; Jennings, S. ; Hiddink, J.G. ; Hintzen, N.T. ; Hinz, H. ; Kaiser, M.J. ; Murray, L.G. - \ 2012
    ICES Journal of Marine Science 69 (2012)4. - ISSN 1054-3139 - p. 682 - 693.
    trawl disturbance - benthic communities - different habitats - scale - sea - regression - abundance - patterns - biomass - size
    Understanding the spatial distribution and intensity of fishing activity is a prerequisite for estimating fishing impacts on seabed biota and habitats. Vessel monitoring system data provide information on fishing activity at large spatial scales. However, successive position records can be too infrequent to describe the complex movements fishing vessels make. High-frequency position data were collected to evaluate how polling frequency and the method of analysis influenced the estimates of fishing impact on the seabed and associated epifaunal communities. Comparisons of known positions with predictions from track interpolation revealed that the performance of interpolation depended on fleet behaviour. Descriptions and indicators of fishing intensity were influenced significantly by the analytical methods (track reconstruction, density of position records) and grid-cell resolution used for the analysis. These factors can lead to an underestimation of fishing impact on epifaunal communities. It is necessary to correct for such errors to quantify the effects of fishing on various ecosystem components and hence to inform ecosystem-based management. Polling at intervals of 30 min would provide a desirable compromise between achieving precise estimates of fishing impacts on the seabed and minimizing the cost of data collection and handling.
    VMStools: Open-source software for the processing, analysis and visualisation of fisheries logbook and VMS data
    Hintzen, N.T. ; Bastardie, F. ; Beare, D.J. ; Piet, G.J. ; Ulrich, C. ; Deporte, N. ; Egekvist, J. ; Degel, H. - \ 2012
    Fisheries Research 115-116 (2012). - ISSN 0165-7836 - p. 31 - 43.
    fishing effort - management strategies - high-resolution - giant petrels - catch - sea - pressure - patterns - impact - scale
    VMStools is a package of open-source software, build using the freeware environment R, specifically developed for the processing, analysis and visualisation of landings (logbooks) and vessel location data (VMS) from commercial fisheries. Analyses start with standardized data formats for logbook (EFLALO) and VMS (TACSAT), enabling users to conduct a variety of analyses using generic algorithms. Embedded functionality handles erroneous data point detection and removal, métier identification through the use of clustering techniques, linking logbook and VMS data together in order to distinguish fishing from other activities, provide high-resolution maps of both fishing effort and -landings, interpolate vessel tracks, calculate indicators of fishing impact as listed under the Data Collection Framework at different spatio-temporal scales. Finally data can be transformed into other existing formats, for example to populate regional databases like FishFrame. This paper describes workflow examples of these features while online material allows a head start to perform these analyses. This software incorporates state-of-the art VMS and logbook analysing methods standardizing the process towards obtaining pan-European, or even worldwide indicators of fishing distribution and impact as required for spatial planning. --------------------------------------------------------------------------------
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