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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    First evidence of a new spawning stock of Illex coindetii in the North Sea (NE-Atlantic)
    Oesterwind, Daniel ; Bobowski, Bianca T.C. ; Brunsch, Anika ; Laptikhovsky, Vladimir ; Hal, Ralf Van; Sell, Anne F. ; Pierce, Graham J. - \ 2020
    Fisheries Research 221 (2020). - ISSN 0165-7836
    North Sea - ommastrephidae - illex - reproduction - distribution - Life cycle
    Global changes drive abundance and distribution of species worldwide. It seems that at least some cephalopodstocks profit from global changes as indicated by increases in biomass and/or expansion of their geographicaldistribution, as appears to be the case for the commercially important ommastrephid squidIllexcoindetii, in theNorth Sea. Based on the recently increased abundance of this species seen in research trawl hauls, here wepresent the first evidence of a summer spawning stock ofIllexcoindetiiin the North Sea and derive a descriptionof its life cycle. Neither mated females nor spent males were reported from the area previously. In quarter 1 themajority ofIllexcoindetiiwere immature (maturity stage 0) and maturing (maturity stage 1–3) while in quarter 3almost exclusively mature and spent individuals (maturity stage 4–6) were caught. We observed up to threespermatangia bundles attached to females in quarter 3, indicating that spawning and reproduction takes place inthe North Sea and that the species is already established in this area. Estimated egg hatching dates suggest aprolonged hatching period and therefore likely a long spawning season, although cold temperature seems tolimit year round reproduction. The intensity of individual migrations from adjacent waters into the North Sea isunknown and therefore the number of individuals staying permanently in the North Sea could not be estimated.It is consequently still unclear whether the North Sea individuals ofI. coindetiiconstitute a new separate stock
    Data from: Explaining European fungal fruiting phenology with climate variability
    Andrew, Carrie ; Heegaard, Einar ; Høiland, Klaus ; Senn-Irlet, Beatrice ; Kuijper, T.W.M. ; Krisai-Greilhuber, Irmgard ; Kirk, Paul M. ; Heilmann-Clausen, Jacob ; Gange, Alan C. ; Egli, Simon ; Bässler, Claus ; Büntgen, Ulf ; Boddy, Lynne ; Kauserud, Håvard - \ 2018
    Swiss Federal Institute for Forest, Snow and Landscape Research WSL
    climate - fungi - fruit bodies - distribution - NDVI - nutritional mode - path analysis - phenology
    Here we assess the impact of geographically dependent (latitude, longitude and altitude) changes in bioclimatic (temperature, precipitation and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path‐analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 days, primarily with latitude. Altitude affected fruiting by up to 30 days, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large‐scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic, as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring‐fruiting ectomycorrhizal fungi. Species‐specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems.
    Explaining European fungal fruiting phenology with climate variability
    Andrew, Carrie ; Heegaard, Einar ; Høiland, Klaus ; Senn-Irlet, Beatrice ; Kuyper, Thomas W. ; Krisai-Greilhuber, Irmgard ; Kirk, Paul M. ; Heilmann-Clausen, Jacob ; Gange, Alan C. ; Egli, Simon ; Bässler, Claus ; Büntgen, Ulf ; Boddy, Lynne ; Kauserud, Håvard - \ 2018
    Ecology 99 (2018)6. - ISSN 0012-9658 - p. 1306 - 1315.
    climate - distribution - Europe - fruit bodies - fungi - NDVI - nutritional mode - path analysis - phenology
    Here we assess the impact of geographically dependent (latitude, longitude, and altitude) changes in bioclimatic (temperature, precipitation, and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 d, primarily with latitude. Altitude affected fruiting by up to 30 d, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large-scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic groups as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring-fruiting ectomycorrhizal fungi. Species-specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems.
    What determines plant species diversity in Central Africa?
    Proosdij, Andreas S.J. van - \ 2017
    Wageningen University. Promotor(en): M.S.M. Sosef, co-promotor(en): N. Raes; J.J. Wieringa. - Wageningen : Wageningen University - ISBN 9789463436618 - 161
    plants - biodiversity - species diversity - species - distribution - biogeography - central africa - biosystematics - tropical rain forests - modeling - planten - biodiversiteit - soortendiversiteit - soorten - distributie - biogeografie - centraal-afrika - biosystematiek - tropische regenbossen - modelleren

    Planet Earth hosts an incredible biological diversity. Estimated numbers of species occurring on Earth range from 5 to 11 million eukaryotic species including 400,000-450,000 species of plants. Much of this biodiversity remains poorly known and many species have not yet been named or even been discovered. This is not surprising, as the majority of species is known to be rare and ecosystems are generally dominated by a limited number of common species.

    Tropical rainforests are the most species-rich terrestrial ecosystems on Earth. The general higher level of species richness is often explained by higher levels of energy near the Equator (latitudinal diversity gradient). However, when comparing tropical rainforest biomes, African rainforests host fewer plant species than either South American or Asian ones. The Central African country of Gabon is situated in the Lower Guinean phytochorical region. It is largely covered by what is considered to be the most species-rich lowland rainforest in Africa while the government supports an active conservation program. As such, Gabon is a perfect study area to address that enigmatic question that has triggered many researchers before: “What determines botanical species richness?”.

    In the past 2.5 million years, tropical rainforests have experienced 21 cycles of global glaciations. They responded to this by contracting during drier and cooler glacials into larger montane and smaller riverine forest refugia and expanding again during warmer and wetter interglacials. The current rapid global climate change coupled with change of land use poses new threats to the survival of many rainforest species. The limited availability of resources for conservation forces governments and NGOs to set priorities. Unfortunately, for many plant species, lack of data on their distribution hampers well-informed decision making in conservation.

    Species distribution models (SDMs) offer opportunities to bridge at least partly this knowledge gap. SDMs are correlative models that infer the spatial distribution of species using only a limited set of known species occurrence records coupled with high resolution environmental data. SDMs are widely applied to study the past, present and future distribution of species, assess the risk of invasive species, infer patterns of species richness and identify hotspots, as well as to assess the impact of climate change. The currently available methods form a pipeline, with which data are selected and cleaned, models selected, parameterized, evaluated and projected to other areas and climatic scenarios, and biodiversity patterns are computed from these SDMs. In this thesis, SDMs of all Gabonese plant species were generated and patterns of species richness and of weighted endemism were computed (chapter 4 & 5).

    Although this pipeline enables the rapid generation of SDMs and inferring of biodiversity patterns, its effective use is limited by several matters of which three are specifically addressed in this thesis. Not knowing the true distribution limits the opportunities to assess the accuracy of models and assess the impact of assumptions and limitations of SDMs. The use of simulated species has been advocated as a method to systematically assess the impact of specific matters of SDMs (virtual ecologist). Following this approach, in chapter 2, I present a novel method to simulate large numbers of species that each have their own unique niche.

    One matter of SDMs that is usually ignored but has been shown to be of great impact on model accuracy is the number of species occurrence records used to train a model. In chapter 2, I quantify the effect of sample size on model accuracy for species of different range size classes. The results show that the minimum number of records required to generate accurate SDMs is not uniform for species of every range size class and that larger sample sizes are required for more widespread species. By applying a uniform minimum number of records, SDMs of narrow-ranged species are incorrectly rejected and SDMs of widespread species are incorrectly accepted. Instead, I recommend to identify and apply the unique minimum numbers of required records for each individual species. The method presented here to identify the minimum number of records for species of particular range size classes is applicable to any species group and study area.

    The range size or prevalence is an important plant feature that is used in IUCN Red List classifications. It is commonly computed as the Extent Of Occurrence (EOO) and Area Of Occupancy (AOO). Currently, these metrics are computed using methods based on the spatial distribution of the known species occurrences. In chapter 3, using simulated species again, I show that methods based on the distribution of species occurrences in environmental parameter space clearly outperform those based on spatial data. In this chapter, I present a novel method that estimates the range size of a species as the fraction of raster cells within the minimum convex hull of the species occurrences, when all cells from the study area are plotted in environmental parameter space. This novel method outperforms all ten other assessed methods. Therefore, the current use of EOO and AOO based on spatial data alone for the purpose of IUCN Red List classification should be reconsidered. I recommend to use the novel method presented here to estimate the AOO and to estimate the EOO from the predicted distribution based on a thresholded SDM.

    In chapter 4, I apply the currently best possible methods to generate accurate SDMs and estimate the range size of species to the large dataset of Gabonese plant species records. All significant SDMs are used here to assess the unique contribution of narrow-ranged, widespread, and randomly selected species to patterns of species richness and weighted endemism. When range sizes of species are defined based on their full range in tropical Africa, random subsets of species best represent the pattern of species richness, followed by narrow-ranged species. Narrow-ranged species best represent the weighted endemism pattern. Moreover, the results show that the applied criterion of widespread and narrow-ranged is crucial. Too often, range sizes of species are computed on their distribution within a study area defined by political borders. I recommend to use the full range size of species instead. Secondly, the use of widespread species, of which often more data are available, as an indicator of diversity patterns should be reconsidered.

    The effect of global climate change on the distribution patterns of Gabonese plant species is assed in chapter 5 using SDMs projected to the year 2085 for two climate change scenarios assuming either full or no dispersal. In Gabon, predicted loss of plant species ranges from 5% assuming full dispersal to 10% assuming no dispersal. However, these numbers are likely to be substantially higher, as for many rare, narrow-ranged species no significant SDMs could be generated. Predicted species turnover is as high as 75% and species-rich areas are predicted to loose many species. The explanatory power of individual future climate anomalies to predicted future species richness patterns is quantified. Species loss is best explained by increased precipitation in the dry season. Species gain and species turnover are correlated with a shift from extreme to average values of annual temperature range.

    In the final chapter, the results are placed in a wider scientific context. First, the results on the methodological aspects of SDMs and their implications of the SDM pipeline are discussed. The method presented in this thesis to simulate large numbers of species offers opportunities to systematically investigate other matters of the pipeline, some of which are discussed here. Secondly, the factors that shape the current and predicted future patterns of plant species richness in Gabon are discussed including the location of centres of species richness and of weighted endemism in relation to the hypothesized location of glacial forest refugia. Factors that may contribute to the lower species richness of African rainforests compared with South American and Asian forests are discussed. I conclude by reflecting on the conservation of the Gabonese rainforest and its plant species as well as on the opportunities SDMs offer for this in the wider socio-economic context of a changing world with growing demand for food and other ecosystem services.

    Unravelling aspects of spatial and temporal distribution of Verticillium dahliae in olive, maple and ash trees and improvement of detection methods
    Keykhasaber, Mojtaba - \ 2017
    Wageningen University. Promotor(en): Bart Thomma; Pierre de Wit, co-promotor(en): Jelle Hiemstra. - Wageningen : Wageningen University - ISBN 9789463430142 - 163
    olea europaea - olives - acer - fraxinus - plant pathogenic fungi - verticillium dahliae - distribution - virulence - detection - olea europaea - olijven - acer - fraxinus - plantenziekteverwekkende schimmels - verticillium dahliae - distributie - virulentie - detectie

    Vascular wilts caused by xylem-colonizing pathogens are among the most devastating plant diseases that affect a wide range of plant species worldwide. Information on the distribution of V. dahliae in infected trees helps to design an appropriate and efficient sampling method for reliable detection of the pathogen in diseased trees. In Chapter 3, the distribution of V. dahliae in young twigs and leaves of infected olive trees is studied by real-time quantification of V. dahliae DNA. Analysis of twig and leaf samples collected from different sides of the crown of infected olive trees showed a non-uniform distribution of the fungus within infected parts of diseased olive trees. It was demonstrated that testing of combined samples comprising subsamples from at least 5 twigs from different sides of the tree, or 5-10 random leaves, can reliably detect the pathogen. V. dahliae isolates that infect olive trees can be classified as defoliating (D) isolates that are highly virulent, or non-defoliating (ND) isolates that are generally less aggressive. Discrimination of these pathotypes is important in order to predict the severity of disease, and decide on appropriate disease management strategies. This is particularly important due to the alarming spread of highly virulent isolates of the D pathotype worldwide. In Chapter 4, a novel method is designed for accurate discrimination and sensitive detection of D and ND isolates of V. dahliae. Through comparative genomics of multiple D and ND isolates of V. dahliae a region was identified that is present in all sequenced ND isolates, while absent from all D isolates. Based on this presence-absence polymorphism, a set of primers was designed spanning this region that was able to generate differentially sized amplicons for isolates that belong to the different pathotypes. Additionally, a nested-PCR assay was designed to increase the sensitivity and improve detection of D and ND isolates in planta. In Chapter 5, the relation of the dynamics in pathogen distribution in infected plants to the differences in extent and severity of disease caused by D and ND isolates in resistant and susceptible olive genotypes is studied. To this end, the distribution of a D (V117) and a ND (V4) isolate of V. dahliae in root-inoculated young plants of a susceptible (Picual) and a partially resistant cultivar (Frantoio) of olive and its relationship to the disease progression was investigated using real-time PCR. The amount of pathogen DNA detected in the two cultivars correlated with their susceptibility to Verticillium wilt, with lower quantities of V4 and V117 DNA detected in ‘Frantoio’ than in ‘Picual’. Also quantities of pathogen DNA in V117-inoculated plants were higher than quantities of pathogen DNA in V4-inoculated plants. The distribution patterns of D and ND isolates in the lower, middle and top parts of tested olive cultivars showed that differences in symptom severity were related to amounts of the pathogen in lower and middle parts of the trees, since colonization of the pathogen in top parts of the stem of inoculated plants was minor and was not significantly different between treatments. Moreover, microscopic analysis of infection and colonization processes of V. dahliae in olive plants inoculated with GFP-labelled isolates revealed that colonization of the above ground tissues of infected olive plants is by means of conidia transported upward with the xylem sap stream. In Chapter 6 we investigated the spatial and temporal distribution of V. dahliae in relation to disease progression and recovery in stem-inoculated maple and ash trees. These species differ strongly in vascular anatomy with maple having a diffuse porous xylem anatomy whereas ash has a ring porous xylem anatomy. Results showed that that differences in the xylem anatomy of ash and maple did not significantly affect the speed and extent of the upward spread of the pathogen in stem-inoculated trees. Nevertheless, the xylem of ash trees is much less supportive for growth and survival of V. dahliae than that of maple trees, as in the year after inoculation disease incidence and also quantities of V. dahliae detected in maple trees were significantly higher than in ash trees. Moreover, V. dahliae could not be reisolated at all from ash trees that had recovered from disease. However, it could be detected by PCR in some cases in the xylem formed in the year of inoculation, never in the xylem formed in the year after inoculation. Nevertheless, V. dahliae easily could be detected in the wood of diseased ash and maple trees in the year after inoculation. Notably, despite the presence of a layer of terminal parenchyma cells between growth rings, in ash trees showing disease symptoms in the year after inoculation V. dahliae was present in the xylem of the new growth ring. It was also observed that in stem-inoculated trees V. dahliae can move downward from the point of inoculation into the root collar, which may provide an avenue for infection of new growth rings in ash trees.

    Distribution of chloramphenicol to tissues, plasma and urine in pigs after oral intake of low doses
    Aspenström-Fagerlund, Bitte ; Nordkvist, Erik ; Törnkvist, Anna ; Wallgren, Per ; Hoogenboom, Ron ; Berendsen, Bjorn ; Granelli, Kristina - \ 2016
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 33 (2016)9. - ISSN 1944-0049 - p. 1411 - 1420.
    Chloramphenicol - distribution - LC-MS/MS - pigs - residues

    Toxic effects of chloramphenicol in humans caused the ban for its use in food-producing animals in the EU. A minimum required performance level (MRPL) was specified for chloramphenicol at 0.3 μg kg–1 for various matrices, including urine. In 2012, residues of chloramphenicol were found in pig urine and muscle without signs of illegal use. Regarding its natural occurrence in straw, it was hypothesised that this might be the source, straw being compulsory for use as bedding material for pigs in Sweden. Therefore, we investigated if low daily doses of chloramphenicol (4, 40 and 400 μg/pig) given orally during 14 days could result in residues in pig tissues and urine. A dose-related increase of residues was found in muscle, plasma, kidney and urine (showing the highest levels), but no chloramphenicol was found in the liver. At the lowest dose, residues were below the MRPL in all tissues except in the urine. However, in the middle dose, residues were above the MRPL in all tissues except muscle, and at the highest dose in all matrices. This study proves that exposure of pigs to chloramphenicol in doses occurring naturally in straw could result in residues above the MRPL in plasma, kidney and especially urine.

    First visual record of a living basking shark Cetorhinus maximus in the Caribbean Sea
    Geelhoed, S.C.V. ; Janinhoff, N. ; Verdaat, J.P. - \ 2016
    Caribbean Journal of Science 49 (2016)1. - ISSN 0008-6452 - p. 76 - 78.
    Aruba - distribution - Dutch Caribbean - Migration - shark
    The occurrence of basking sharks in the Caribbean Sea is only recently documented by satellite tagging studies, which show that some individuals migrate through the region en route from waters off the east coast of the USA to waters off northeastern South-America. The observation of a basking shark on 7 November 2013 ca. 130 km north-northeast of Aruba during an aerial survey of marine mammals in the waters around the Dutch Leeward Islands is reported. This observation constitutes the first visual record of a living basking shark in the Caribbean.
    Private Environmental Governance in the Ethiopian Pesticide Supply Chain: Importation, Distribution and Use
    Mengistie, B.T. ; Mol, A.P.J. ; Oosterveer, P.J.M. - \ 2016
    NJAS Wageningen Journal of Life Sciences 76 (2016). - ISSN 1573-5214 - p. 65 - 73.
    pesticides - distribution - use - supply chain actors - private environmental governance - Ethiopia
    Agricultural pesticides are important chemicals that are used to mitigate crop damage or loss and improve productivity. However, pesticides may cause negative environmental and human health effects depending on their specific distribution and use. Securing environmental safety and sustainability of pesticide distribution and use is widely seen as an important challenge for pesticide governance. This paper analyses how, why and under what circumstances Ethiopian pesticide supply chain actors deal with (un)safe distribution and use of pesticides and assesses their potential contribution to securing the quality, environmental safety and sustainability of pesticides importation, distribution and use. The framework developed for this is based on sustainable supply chain governance in order to assess the roles of and the interactions between the different chain actors, supporters and influencers. On the basis of field research in Ethiopia among key chain actors (importers, retailers, farmers) we analyse their involvement in three different environmental governance mechanisms: governing material flows of pesticides, managing information on health and environmental safety and providing training and capacity-building services. The study found the organisation of the pesticides supply chain in Ethiopia as atomistic. Environment and health hardly played a role in pesticides handling by the different supply chain actors, which was dominated by immediate profit motives. As a consequence smallholder farmers are put at risk because they are refrained from training, support or information provision on pesticides. Indeed, it was a failure of state governance that led importers and retailers to aggressive marketing and distributing pesticides unsafely and hinder the proliferate of private mode of governance. At the same time, a small signs of hope have also been identified at the supporters’ and influencers’ side of the chain. Successful environmental supply chain governance for safe pesticide distribution and use requires coordination and as well as training and information sharing (interaction) among pesticide supply chain actors, supporters and influencers at all levels-local, national and global as elements of one system of governance. Finally, the evidence presented in this paper suggests that due to limits in governmental capacity and concerns on commercial viability and on social and environmental impacts among private actors, there will be a role for private actors alongside public actors to ensure safe pesticide distribution and use. Public-private partnerships might constitute an attractive strategy for this aim.
    Characterization of (Glucurono)arabinoxylans from Oats Using Enzymatic Fingerprinting
    Tian, Lingmin ; Gruppen, Harry ; Schols, Henk A. - \ 2015
    Journal of Agricultural and Food Chemistry 63 (2015)50. - ISSN 0021-8561 - p. 10822 - 10830.
    arabinoxylan - Avena sativa - cell wall polysaccharides - distribution - enzymatic fingerprinting - oats

    Cell wall material from whole oat grains was sequentially extracted to study the structural characteristics of individual arabinoxylan (AX) populations. Araf was singly substituted at both O-3 (mainly) and O-2 positions of Xylp, and no disubstitution of Xylp with Araf residues was found in oat AXs. Both highly substituted and sparsely substituted segments were found in AXs in Ba(OH)2 extracts, whereas AXs in 1 and 6 M NaOH extracts were rarely branched and easily aggregated. Both O-2-linked GlcA and 4-O-MeGlcA residues were present in oat AXs. A series of AX oligomers with galactose as a substituent was detected for the first time in oats. The present study suggested that the distribution of Araf was contiguous in oat AXs, different from the homogeneous distribution of Araf in wheat and barley AXs, which might result in different fermentation patterns in humans and animals.

    North Sea mackerel egg survey in May and June 2015
    Damme, C.J.G. van - \ 2015
    IJmuiden : IMARES (Report / Centrum voor Visserijonderzoek (CVO) 15.010) - 39
    makrelen - visseneieren - kuitschieten - distributie - visbestand - noordzee - mackerels - fish eggs - spawning - distribution - fishery resources - north sea
    After technical problems prevented the North Sea mackerel egg survey to be carried out in 2014, a successful survey was carried out in May-June 2015. The survey was carried out on board ‘RV Tridens’. The expected mackerel spawning area was covered in each of four periods in east-west transects, separated by 1 degree. In total 260 valid plankton hauls with a Gulf VII plankton sampler were performed, as well as 3 fish hauls and 4 sets of flowmeter calibrations hauls.
    Eutrophication, Nile perch and food-web interactions in south-east Lake Victoria
    Cornelissen, I.J.M. - \ 2015
    Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Leo Nagelkerke; R. Vijverberg. - Wageningen : Wageningen University - ISBN 9789462575660 - 163
    lates niloticus - eutrofiëring - voedselwebben - interacties - visserijbiologie - visstand - dynamica - fytoplankton - distributie - voedingsgedrag - victoriameer - tanzania - lates niloticus - eutrophication - food webs - interactions - fishery biology - fish stocks - dynamics - phytoplankton - distribution - feeding behaviour - lake victoria - tanzania

    The increasing eutrophication, the introduction of Nile perch (Lates niloticus) and the increasing fishing pressure has changed Lake Victoria tremendously the last century. Since the 1960s, eutrophication increased primary production, enabling an increase in fish production. However, eutrophication also created hypoxia pockets, which reduced the available habitats for fish. In addition, the endemic haplochromines declined, whereas the introduced Nile perch boomed in the 1980s. The Nile perch boom and increased fish production resulted in the largest freshwater fisheries of the world. However, it is unclear whether fish production can still increase with further eutrophication as maximum primary production rates may have been reached. Fish stocks fluctuate since the 1980s and in order to manage these, it is important to understand how eutrophication and fisheries affect the Nile perch population. The present study investigates the bottom-up effects of eutrophication on the Nile perch and food-web dynamics in south-east Lake Victoria. We analysed the level of eutrophication along an eutrophication gradient in the Mwanza Gulf. Phytoplankton biomass varied spatially and seasonally and was limited by nutrients in deep water and by light in shallow water. Fish distributions were dynamic, with environmental factors depth and temperature influencing Nile perch size structure and distribution patterns similarly on small and large spatial scales. Although prey densities of haplochromines and Caridina nilotica shrimp did not explain Nile perch distributions, ontogenetic diet shifts and composition were related to prey densities, suggesting an opportunistic feeding behaviour of Nile perch. Small Nile perch however, showed some preference to shrimp and Nile perch preferred haplochromines above Dagaa (Rastrineobola argentea) and juvenile Nile perch as fish prey. On a food-web level, the base of the food web was spatially and seasonally highly dynamic. The onset of rains caused a spatial differentiation in littoral/benthic and pelagic carbon sources, affecting the whole food web. Trophic levels of fish were related to the spatial variation in diet compositions. Although a large heterogeneity was found in water quality, fish distributions and food-web structure, bottom-up processes affected the food web similarly. Despite the ongoing nutrient load in Lake Victoria, water quality has improved since the 1990s. Climate forcing through increasing wind speeds increased visibility and oxygen levels. Global climate change will therefore be an important driver of the water quality and fish distributions of Lake Victoria.

    Perspectives on the distribution of fresh food in emerging metropolises: the cases of Mexico City and Cairo
    Waldhauer, N. ; Burgh, M. van der; Vorst, J.G.A.J. van der; Bing, X. ; Scheer, F.P. - \ 2015
    Wageningen : Wageningen UR - Food & Biobased Research (Report / Wageningen UR Food & Biobased Research 1529) - ISBN 9789462573642 - 56
    voedsel - distributie - voedseldistributieprogramma's - ketenmanagement - voedselketens - logistiek - efficiëntie - stedelijke gebieden - mexico - voedselzekerheid - voedselkwaliteit - voedselverspilling - duurzaamheid (sustainability) - food - distribution - food distribution programs - supply chain management - food chains - logistics - efficiency - urban areas - mexico - food security - food quality - food wastage - sustainability
    The report consists of four main chapters. In chapter 2 a theoretical framework of urban food distribution is developed based on earlier projects, a literature study and interviews. This framework underlines the main elements of urban food distribution and serves as a theoretical outline for the following case studies and recommendations for improvement. Chapter 3 describes the current situation of fresh food distribution in the two chosen case studies Mexico City and Cairo using the framework of chapter 2 as a reference. Chapter 4 presents the conclusions from the case studies comparing the current situation of the respective urban fresh food distribution networks, assessing the performance of the system and stating the major challenges in both cities. Recommendations for intervention are given in chapter 5 taking into account the conclusions from the case studies, urban distribution initiatives and projects in Western European cities and expert interviews. Chapter 6 gives an outlook into further research.
    Extensive literature search for preparatory work to support pan European pest risk assessment: Trichilogaster acaciaelongifoliae RC/EFS/ALPHA/2014/07
    Derkx, M.P.M. ; Brouwer, J.H.D. ; Breda, P.J.M. van; Helsen, H.H.M. ; Hoffman, M.H.A. ; Hop, M.E.C.M. - \ 2014
    Parma, It. : EFSA (EFSA supporting publication 2015- EN-764) - 71
    acacia - acacia longifolia - houtachtige planten als sierplanten - distributie - onkruiden - invasieve exoten - geïntroduceerde soorten - biologische bestrijding - organismen ingezet bij biologische bestrijding - hymenoptera - risicoschatting - europa - acacia - acacia longifolia - ornamental woody plants - distribution - weeds - invasive alien species - introduced species - biological control - biological control agents - hymenoptera - risk assessment - europe
    The European Commission is currently seeking advice from EFSA (Mandate M-2012-0272) to assess for Arabis mosaic virus, Raspberry ringspot virus, Strawberry latent ringspot virus, Tomato black ring virus, Strawberry mild yellow edge virus, Strawberry crinkle virus, Daktulosphaira vitifoliae, Eutetranychus orientalis, Parasaissetia nigra, Clavibacter michiganensis spp. michiganensis, Xanthomonas campestris pv. vesicatoria, Didymella ligulicola and Phytophthora fragariae the risk to plant health for the EU territory and to evaluate the effectiveness of risk reduction options in reducing the level of risk. In addition, the Panel is requested to provide an opinion on the effectiveness of the present EU requirements against these organisms laid down in Council Directive 2000/29/EC. As a consequence EFSA needs insight in the cropping practices of Citrus spp., Fragaria x ananassa, Ribes spp., Rubus spp., Vaccinium spp., Humulus lupulus, Vitis vinifera, Prunus armeniaca, P. avium, P. cerasus, P. domestica and P. persica, which are host plants for these pests. An extensive and systematic literature search was done in which scientific and grey/technical literature was retrieved from the 28 EU Member States, Iceland and Norway. All references were stored in EndNote libraries, separately for scientific literature and grey/technical literature. For each reference information is provided on the source/search strategy, the crop, the country, the topic (cropping practice, propagation, protection or irrigation (only for Citrus)) and protected cultivation vs. field production. Yields of references depended on the crop and on the country. Over 27,000 references were provided to EFSA. This allows EFSA to quickly find information on crop production, both indoors and outdoors, of all crops that were studied in this extensive literature search. The data can be used by EFSA for the present mandate, but are also an excellent basis for other current and future mandates.
    Mogelijkheden voor de implementatie van het biomassawerf concept in de Greenport Betuwse Bloem : Deel 2. Het biomassawerf concept : voorbeelden, theorie & checklist
    Annevelink, E. ; Gogh, J.B. van; Oever, M.J.A. van den; Dam, J.E.G. van; Bartels, P. - \ 2014
    Wageningen : Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research 1478) - ISBN 9789461739933 - 57
    logistiek - biomassa - ketenmanagement - distributie - biobased economy - betuwe - logistics - biomass - supply chain management - distribution - biobased economy - betuwe
    Het project ‘Biomassawerf – verwerken van reststromen’ (BO-21.03-001) vormt een onderdeel van het Biobased gedeelte van het BO-programma Keteninnovaties Plantaardig (KIP) van het Ministerie van Economische Zaken. Deze nota is het tweede deel van de rapportage uit dit project, en is een vervolg op de nota: ‘Deel 1. Stakeholder analyse & biomassabeschikbaarheid’ (Annevelink et al., 2013). Het specifieke doel van dit tweede deelrapport is om enkele gevonden voorbeelden van het biomassawerf concept te schetsen, om de theorie verder uit te diepen en om een checklist op te stellen met stappen om tot een biomassawerf te komen.
    Marine mammals in the Wider Caribbean - Current research and priorities for future studies
    Lucke, K. ; Scheidat, M. ; Geelhoed, S.C.V. ; Debrot, A.O. - \ 2014
    Den Helder : IMARES (Report / IMARES Wageningen UR C007/14) - 38
    zeezoogdieren - distributie - populatiedynamica - beschermingsgebieden - kennisoverdracht - caribische zee - marine mammals - distribution - population dynamics - conservation areas - knowledge transfer - caribbean sea
    Information on the distribution, abundance and ecology of marine mammal in the Wider Caribbean Region is scarce. This report aims at collating the on-going research in the Wider Caribbean Region, at identifying the most critical knowledge gaps that need to be addressed to inform and facilitate conservation actions and assess the most suitable research techniques to fill these knowledge gaps.
    Verslogistiek sierteelt
    Jong, Wim de - \ 2013
    forest nurseries - ornamental woody plants - ornamental horticulture - business management - logistics - distribution - agricultural education - simulation models - usage - projects - project implementation - students
    Mogelijkheden voor de implementatie van het biomassawerf concept in de Greenport Betuwse Bloem : deel 1. Stakeholder analyse & biomassabeschikbaarheid
    Annevelink, E. ; Gogh, J.B. van; Dam, J.E.G. van; Bartels, P.V. - \ 2013
    Wageningen : Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research 1416) - ISBN 9789461736970 - 75
    biomassa - ketenmanagement - logistiek - distributie - biobased economy - betuwe - biomass - supply chain management - logistics - distribution - biobased economy - betuwe
    Biomassawerven kunnen een centrale rol spelen bij de integrale aanpak van biomassaketens voor de biobased economy. Een biomassawerf heeft de rol om bij de aanbodkant verschillende soorten biomassastromen te verzamelen, eventueel voor te bewerken en ze vervolgens aan te bieden aan de verwerkingskant. Het hoofddoel van het project is te onderzoeken of het biomassawerfconcept haalbaar is om de beschikbaarheid van regionale biomassa voor economische verwerking te vergroten. Onderzoek moet uitwijzen hoe biomassawerven het beste kunnen worden opgezet, en hoe een netwerk van biomassawerven eruit zal komen te zien. Als case voor het onderzoek dient de Greenport Betuwse Bloem (GBB) in de Provincie Gelderland. Het subdoel van dit rapport is een nadere stakeholderanalyse van de GBB, waarbij de huidige situatie en wensen voor de toekomst in beeld worden gebracht. Verder is een inschatting gemaakt van de potentieel beschikbare biomassastromen binnen de GBB.
    Animal genetic resources: conservation-breeding-regulatory framework
    Hiemstra, Sipke Joost - \ 2012
    livestock farming - agro-biodiversity - genetic diversity - animal genetic resources - genetic improvement - animal breeding - sustainable animal husbandry - gene banks - breeds - distribution
    Making a better world: Carrier, retailer, and consumer support for sustainability initiatives in the context of urban distribution and retailing
    Hofenk, D.J.B. - \ 2012
    Open University. Promotor(en): J. Semeijn; J.M.M. Bloemer, co-promotor(en): M.J.H. van Birgelen. - Enschede : s.n. - ISBN 9789461914255 - 148
    duurzaamheid (sustainability) - distributie - consumenten - marketing voor de detailhandel - kooplieden - transport - stedelijke gebieden - steden - nederland - sustainability - distribution - consumers - retail marketing - merchants - transport - urban areas - towns - netherlands
    Consumenten zijn bereid om duurzame producten en duurzaam vervoer van producten naar winkels in de binnenstad te steunen, zelfs wanneer dit betekent dat ze meer moeten betalen voor producten. Maar dit geldt alleen als zij daartoe een morele verplichting voelen en de sociale druk niet te groot wordt. Winkeliers en transporteurs willen een dergelijke duurzame vorm van stedelijke distributie, zoals Binnenstadservice in Nijmegen, steunen als het initiatief vertrouwenwekkend is, zonder financieel nadeel. Dit stelt Dianne Hofenk op basis van haar promotieonderzoek naar factoren die de steun voor duurzame initiatieven voor stedelijke distributie en detailhandel beïnvloeden.
    Ex-ante analyse wetsvoorstel stelsel van verantwoorde mestafzet
    Koeijer, T.J. de; Luesink, H.H. ; Ham, A. van den - \ 2012
    Den Haag : LEI Wageningen UR (Nota / LEI Wageningen UR : Onderzoeksveld Sector en ondernemerschap ) - 38
    mestverwerking - dierlijke meststoffen - marketingkanalen - distributie - scenario-analyse - manure treatment - animal manures - marketing channels - distribution - scenario analysis
    Invoering van verplichte mestverwerking kan op middellange termijn (2015) het tekort aan afzetmogelijkheden voor dierlijke mest oplossen en daarmee de druk op de mestmarkt opheffen. Een voorwaarde daarbij is dat de verwerkingscapaciteit van dierlijke mest zodanig toeneemt dat er niet langer sprake is van een tekort aan afzetmogelijkheden van mest.
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