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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    Tracing hydrological connectivity
    Antonelli, Marta - \ 2020
    Wageningen University. Promotor(en): A.J. Teuling; R. Uijlenhoet, co-promotor(en): L. Pfister. - Wageningen : Wageningen University - ISBN 9789463953870 - 186
    Saturated areas through the lens: 2. Spatio-temporal variability of streamflow generation and its relationship with surface saturation
    Antonelli, Marta ; Glaser, Barbara ; Teuling, Adriaan J. ; Klaus, Julian ; Pfister, Laurent - \ 2020
    Hydrological Processes 34 (2020)6. - ISSN 0885-6087 - p. 1333 - 1349.
    catchment hydrology - hydrological connectivity - intracatchments variability - riparian processes - stream network dynamics - streamflow generation - surface saturation dynamics - topographic controls

    Investigating the spatio-temporal variability of streamflow generation is fundamental to interpret the hydrological and biochemical functioning of catchments. In humid temperate environments, streamflow generation is often linked to the occurrence of near stream surface saturated areas, which mediate hydrological connectivity between hillslopes and streams. In this second contribution of a series of two papers, we used salt dilution gauging to investigate the spatio-temporal variability of streamflow in different subcatchments and for different reaches in the Weierbach catchment (0.42 km2) and explored the topographical controls on streamflow variability. Moreover, we mapped stream network expansion and contraction dynamics. Finally, we combined the information on the spatio-temporal variability of streamflow with the characterization of riparian surface saturation dynamics of seven different areas within the catchment (mapped with thermal infrared imagery, as presented in our first manuscript). We found heterogeneities in the streamflow contribution from different portions of the catchment. Although the size of the contributing area could explain differences in subcatchments' and reaches' net discharge, no clear topographic controls could be found when considering the area-normalized discharge. This suggests that some local conditions exert control on the variability of specific discharge (e.g., local bedrock characteristics and occurrence of perennial springs). Stream network dynamics were found not to be very responsive to changes in catchment's discharge (i.e., total active stream length vs. stream outlet discharge relationship could be described through a power law function with exponent = 0.0195). On the contrary, surface saturation dynamics were found to be in agreement with the level of streamflow contribution from the correspondent reach in some of the investigated riparian areas. This study represents an example of how the combination of different techniques can be used to characterize the internal heterogeneity of the catchment and thus improve our understanding of how hydrological connectivity is established and streamflow is generated.

    Saturated areas through the lens: 1. Spatio-temporal variability of surface saturation documented through thermal infrared imagery
    Antonelli, Marta ; Glaser, Barbara ; Teuling, Adriaan J. ; Klaus, Julian ; Pfister, Laurent - \ 2020
    Hydrological Processes 34 (2020)6. - ISSN 0885-6087 - p. 1310 - 1332.
    catchment hydrology - ground-based thermal infrared imagery - intracatchment variability - remote sensing - riparian processes - surface saturation dynamics - surface saturation mapping

    Surface saturated areas are key features in generating run-off. A detailed characterization of the expansion and contraction of surface saturation in riparian zones and its connectivity to the stream is fundamental to improve our understanding of the spatial and temporal variability of streamflow generation processes. In this first contribution of a series of two papers, we used ground-based thermal infrared imagery for characterizing riparian surface saturation seasonal dynamics of seven different riparian areas in the Weierbach catchment (0.42 km2), a small forested catchment in Luxembourg. We collected biweekly panoramic images of the seven areas over a period of 2 years. We identified the extension of saturation in each collected panoramic image (i.e., percentage of pixels corresponding to saturated surfaces in each riparian area) to generate time series of surface saturation. Riparian surface saturation in all areas was seasonally variable, and its dynamics were in accordance with lower hillslope groundwater level fluctuations. Surface saturation in the different areas related to catchment outlet discharge through power law relationships. Differences in these relationships for different areas could be associated with the location of the areas along the stream network and to a possible influence of local riparian morphology on the development of surface saturation, suggesting a certain degree of intracatchment heterogeneity. This study paves the way for a subsequent investigation of the spatio-temporal variability of streamflow generation in the catchment, presented in our second contribution.

    Temporal and spatial variability of terrestrial diatoms at the catchment scale: Controls on communities
    Foets, Jasper ; Wetzel, Carlos E. ; Teuling, Adriaan J. ; Pfister, Laurent - \ 2020
    PeerJ 2020 (2020)1. - ISSN 2167-8359
    Agriculture - Algae - Ecology - Indicator species - Soil

    Diatoms are generally regarded as inhabitants of water bodies. However, numerous taxa are able to survive and reproduce in a variety of non-aquatic ecosystems. Although terrestrial diatoms are discussed extensively in the literature, most of those studies covered floristic aspects and few information exists on their ecology. This lack of knowledge thwarts their potential use as environmental markers in various applications. As a way forward, we investigated the seasonal patterns and the role of different disturbances on the community composition. We collected soil diatom samples in 16 sites across the Attert River basin (Luxembourg) every 4 weeks for a period of 14 months. Our results indicate that forests create a stable microhabitat for diatoms and that temporal variation of the diatom communities is mainly controlled by farming practices rather than seasonal changes in environmental variables. We also found out that communities need one to 2 months to reestablish a new, stable community after a significant change in the environment. We were able to confirm the applicability of the Pollution-Sensitivity Index (IPS) to identify anthropic disturbances.

    Twenty-three unsolved problems in hydrology (UPH)–a community perspective
    Blöschl, Günter ; Bierkens, Marc F.P. ; Chambel, Antonio ; Cudennec, Christophe ; Destouni, Georgia ; Fiori, Aldo ; Kirchner, James W. ; McDonnell, Jeffrey J. ; Savenije, Hubert H.G. ; Sivapalan, Murugesu ; Stumpp, Christine ; Toth, Elena ; Volpi, Elena ; Carr, Gemma ; Lupton, Claire ; Salinas, Josè ; Széles, Borbála ; Viglione, Alberto ; Aksoy, Hafzullah ; Allen, Scott T. ; Amin, Anam ; Andréassian, Vazken ; Arheimer, Berit ; Aryal, Santosh K. ; Baker, Victor ; Bardsley, Earl ; Barendrecht, Marlies H. ; Bartosova, Alena ; Batelaan, Okke ; Berghuijs, Wouter R. ; Beven, Keith ; Blume, Theresa ; Bogaard, Thom ; Borges de Amorim, Pablo ; Böttcher, Michael E. ; Boulet, Gilles ; Breinl, Korbinian ; Brilly, Mitja ; Brocca, Luca ; Buytaert, Wouter ; Castellarin, Attilio ; Castelletti, Andrea ; Chen, Xiaohong ; Chen, Yangbo ; Chen, Yuanfang ; Chifflard, Peter ; Claps, Pierluigi ; Clark, Martyn P. ; Collins, Adrian L. ; Croke, Barry ; Dathe, Annette ; David, Paula C. ; Barros, Felipe P.J. de; Rooij, Gerrit de; Baldassarre, Giuliano Di; Driscoll, Jessica M. ; Duethmann, Doris ; Dwivedi, Ravindra ; Eris, Ebru ; Farmer, William H. ; Feiccabrino, James ; Ferguson, Grant ; Ferrari, Ennio ; Ferraris, Stefano ; Fersch, Benjamin ; Finger, David ; Foglia, Laura ; Fowler, Keirnan ; Gartsman, Boris ; Gascoin, Simon ; Gaume, Eric ; Gelfan, Alexander ; Geris, Josie ; Gharari, Shervan ; Gleeson, Tom ; Glendell, Miriam ; Gonzalez Bevacqua, Alena ; González-Dugo, María P. ; Grimaldi, Salvatore ; Gupta, A.B. ; Guse, Björn ; Han, Dawei ; Hannah, David ; Harpold, Adrian ; Haun, Stefan ; Heal, Kate ; Helfricht, Kay ; Herrnegger, Mathew ; Hipsey, Matthew ; Hlaváčiková, Hana ; Hohmann, Clara ; Holko, Ladislav ; Hopkinson, Christopher ; Hrachowitz, Markus ; Illangasekare, Tissa H. ; Inam, Azhar ; Innocente, Camyla ; Istanbulluoglu, Erkan ; Jarihani, Ben ; Kalantari, Zahra ; Kalvans, Andis ; Khanal, Sonu ; Khatami, Sina ; Kiesel, Jens ; Kirkby, Mike ; Knoben, Wouter ; Kochanek, Krzysztof ; Kohnová, Silvia ; Kolechkina, Alla ; Krause, Stefan ; Kreamer, David ; Kreibich, Heidi ; Kunstmann, Harald ; Lange, Holger ; Liberato, Margarida L.R. ; Lindquist, Eric ; Link, Timothy ; Liu, Junguo ; Loucks, Daniel Peter ; Luce, Charles ; Mahé, Gil ; Makarieva, Olga ; Malard, Julien ; Mashtayeva, Shamshagul ; Maskey, Shreedhar ; Mas-Pla, Josep ; Mavrova-Guirguinova, Maria ; Mazzoleni, Maurizio ; Mernild, Sebastian ; Misstear, Bruce Dudley ; Montanari, Alberto ; Müller-Thomy, Hannes ; Nabizadeh, Alireza ; Nardi, Fernando ; Neale, Christopher ; Nesterova, Nataliia ; Nurtaev, Bakhram ; Odongo, Vincent O. ; Panda, Subhabrata ; Pande, Saket ; Pang, Zhonghe ; Papacharalampous, Georgia ; Perrin, Charles ; Pfister, Laurent ; Pimentel, Rafael ; Polo, María J. ; Post, David ; Prieto Sierra, Cristina ; Ramos, Maria Helena ; Renner, Maik ; Reynolds, José Eduardo ; Ridolfi, Elena ; Rigon, Riccardo ; Riva, Monica ; Robertson, David E. ; Rosso, Renzo ; Roy, Tirthankar ; Sá, João H.M. ; Salvadori, Gianfausto ; Sandells, Mel ; Schaefli, Bettina ; Schumann, Andreas ; Scolobig, Anna ; Seibert, Jan ; Servat, Eric ; Shafiei, Mojtaba ; Sharma, Ashish ; Sidibe, Moussa ; Sidle, Roy C. ; Skaugen, Thomas ; Smith, Hugh ; Spiessl, Sabine M. ; Stein, Lina ; Steinsland, Ingelin ; Strasser, Ulrich ; Su, Bob ; Szolgay, Jan ; Tarboton, David ; Tauro, Flavia ; Thirel, Guillaume ; Tian, Fuqiang ; Tong, Rui ; Tussupova, Kamshat ; Tyralis, Hristos ; Uijlenhoet, Remko ; Beek, Rens van; Ent, Ruud J. van der; Ploeg, Martine van der; Loon, Anne F. Van; Meerveld, Ilja van; Nooijen, Ronald van; Oel, Pieter R. van; Vidal, Jean Philippe ; Freyberg, Jana von; Vorogushyn, Sergiy ; Wachniew, Przemyslaw ; Wade, Andrew J. ; Ward, Philip ; Westerberg, Ida K. ; White, Christopher ; Wood, Eric F. ; Woods, Ross ; Xu, Zongxue ; Yilmaz, Koray K. ; Zhang, Yongqiang - \ 2019
    Hydrological Sciences Journal 64 (2019)10. - ISSN 0262-6667 - p. 1141 - 1158.
    hydrology - interdisciplinary - knowledge gaps - research agenda - science questions

    This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.

    The potential of different semi-natural habitats to sustain pollinators and natural enemies in European agricultural landscapes
    Bartual, Agustín M. ; Sutter, Louis ; Bocci, Gionata ; Moonen, Anna Camilla ; Cresswell, James ; Entling, Martin ; Giffard, Brice ; Jacot, Katja ; Jeanneret, Philippe ; Holland, John ; Pfister, Sonja ; Pintér, Orsolya ; Veromann, Eve ; Winkler, Karin ; Albrecht, Matthias - \ 2019
    Agriculture, Ecosystems and Environment 279 (2019). - ISSN 0167-8809 - p. 43 - 52.
    Agroecology - Bees - Biodiversity conservation - Conservation biological control - Integrated pest management - Natural enemies - Pollinators - Semi-natural habitat management

    Semi-natural habitats (SNH) are vital to sustain pollinators and natural enemies, and the ecosystem services they provide in agroecosystems. However, little is known about the relative importance of different SNH types and their vegetation traits for pollinators and natural enemies. Yet, such knowledge is essential for effective habitat management to promote both functional arthropod groups and associated multiple ecosystem services. We quantified vegetation traits and abundances of pollinators (bees) and natural enemies (predatory flies and parasitic wasps) in 217 SNH differing in type (woody or herbaceous) and shape (linear or areal habitats), for edge and interior locations within each SNH patch with respect to adjacent crops, across 62 agricultural landscapes in four European countries. Pollinators and natural enemies responded distinctively to major SNH types and within-habitat location of SNH: abundance of natural enemies (predatory flies and parasitic wasps) was higher along woody habitat edges than herbaceous SNH or the interior of woody habitats. In contrast, bee abundances, especially of honey bees, were generally higher in areal herbaceous compared to woody SNH. Abundances of both wild bees and managed honey bees were lowest for the interior sampling location in areal woody habitats. These findings reflected divergent key vegetation traits driving pollinator and natural enemy abundances across SNH: bee pollinators increased with herbaceous plant cover and were well predicted by SNH type and the floral abundance of identified key plant trait groups. In contrast, floral abundances of these plant groups were poor predictors of the studied natural enemies, which were better predicted by SNH type and sampling location within SNH. Our findings stress the need to move beyond the simplistic pooling of SNH types and highlight the importance of considering their vegetation traits to more reliably predict pollinators and natural enemies in agroecosystems. They suggest that the floral abundance of key groups of flowering plants is crucial for habitat management to promote bee pollinators, while vegetation-structural traits appear more important for predatory flies and parasitoids. The distinct importance of different SNH types and associated vegetation traits for pollinators and natural enemies calls for agroecosystem management ensuring diverse SNH with complementary vegetation traits to concomitantly foster pollination and pest control services.

    Technical note : Mapping surface-saturation dynamics with thermal infrared imagery
    Glaser, Barbara ; Antonelli, Marta ; Chini, Marco ; Pfister, Laurent ; Klaus, Julian - \ 2018
    Hydrology and Earth System Sciences 22 (2018)11. - ISSN 1027-5606 - p. 5987 - 6003.

    Surface saturation can have a critical impact on runoff generation and water quality. Saturation patterns are dynamic, thus their potential control on discharge and water quality is also variable in time. In this study, we assess the practicability of applying thermal infrared (TIR) imagery for mapping surface-saturation dynamics. The advantages of TIR imagery compared to other surface-saturation mapping methods are its large spatial and temporal flexibility, its non-invasive character, and the fact that it allows for a rapid and intuitive visualization of surface-saturated areas. Based on an 18-month field campaign, we review and discuss the methodological principles, the conditions in which the method works best, and the problems that may occur. These considerations enable potential users to plan efficient TIR imagery-mapping campaigns and benefit from the full potential offered by TIR imagery, which we demonstrate with several application examples. In addition, we elaborate on image post-processing and test different methods for the generation of binary saturation maps from the TIR images. We test the methods on various images with different image characteristics. Results show that the best method, in addition to a manual image classification, is a statistical approach that combines the fitting of two pixel class distributions, adaptive thresholding, and region growing.

    A pan-European model of landscape potential to support natural pest control services
    Rega, Carlo ; Bartual, Agustín M. ; Bocci, Gionata ; Sutter, Louis ; Albrecht, Matthias ; Moonen, Anna Camilla ; Jeanneret, Philippe ; Werf, Wopke van der; Pfister, Sonja C. ; Holland, John M. ; Paracchini, Maria Luisa - \ 2018
    Ecological Indicators 90 (2018). - ISSN 1470-160X - p. 653 - 664.
    Biological control - Green infrastructure - Landscape complexity - Landscape design - Natural pest control - Semi-natural habitats
    Pest control by natural enemies (natural pest control) is an important regulating ecosystem service with significant implications for the sustainability of agro-ecosystems. The presence of semi-natural habitats and landscape heterogeneity are key determinants of the delivery of this service. However, to date, synthetic and consistent indicators at large scales are lacking. We developed a pan-European, spatially-explicit model to map and assess the landscape potential to sustain natural pest control. The model considers landscape composition in terms of semi-natural habitats types, abundance, spatial configuration and distance from the focal field. It combines recent high-resolution geospatial layers with empirical results from extensive field surveys measuring the specific contribution of different semi-natural habitats to support insects flying enemies providing natural pest control. The resulting maps facilitate a comparison of the relative biological control potential of different areas and show that currently a large proportion of high-productive agricultural areas in Europe has low potential. The obtained indicator can inform the formulation of policies and planning strategies aimed at increasing biodiversity and ecosystem services and can be used to assess trade-offs between different services. Potential fields of application include the Common Agricultural Policy and the EU Biodiversity Strategy, in particular the implementation of Green Infrastructure.
    The WULCA consensus characterization model for water scarcity footprints : assessing impacts of water consumption based on available water remaining (AWARE)
    Boulay, Anne Marie ; Bare, Jane ; Benini, Lorenzo ; Berger, Markus ; Lathuillière, Michael J. ; Manzardo, Alessandro ; Margni, Manuele ; Motoshita, Masaharu ; Núñez, Montserrat ; Pastor, Amandine Valerie ; Ridoutt, Bradley ; Oki, Taikan ; Worbe, Sebastien ; Pfister, Stephan - \ 2018
    The International Journal of Life Cycle Assessment 23 (2018)2. - ISSN 0948-3349 - p. 368 - 378.
    Impact assessment - LCIA - Life cycle assessment - UNEP-SETAC life cycle initiative - Water consumption - Water footprint - Water stress - Water use - WULCA

    Purpose: Life cycle assessment (LCA) has been used to assess freshwater-related impacts according to a new water footprint framework formalized in the ISO 14046 standard. To date, no consensus-based approach exists for applying this standard and results are not always comparable when different scarcity or stress indicators are used for characterization of impacts. This paper presents the outcome of a 2-year consensus building process by the Water Use in Life Cycle Assessment (WULCA), a working group of the UNEP-SETAC Life Cycle Initiative, on a water scarcity midpoint method for use in LCA and for water scarcity footprint assessments. Methods: In the previous work, the question to be answered was identified and different expert workshops around the world led to three different proposals. After eliminating one proposal showing low relevance for the question to be answered, the remaining two were evaluated against four criteria: stakeholder acceptance, robustness with closed basins, main normative choice, and physical meaning. Results and discussion: The recommended method, AWARE, is based on the quantification of the relative available water remaining per area once the demand of humans and aquatic ecosystems has been met, answering the question “What is the potential to deprive another user (human or ecosystem) when consuming water in this area?” The resulting characterization factor (CF) ranges between 0.1 and 100 and can be used to calculate water scarcity footprints as defined in the ISO standard. Conclusions: After 8 years of development on water use impact assessment methods, and 2 years of consensus building, this method represents the state of the art of the current knowledge on how to assess potential impacts from water use in LCA, assessing both human and ecosystem users’ potential deprivation, at the midpoint level, and provides a consensus-based methodology for the calculation of a water scarcity footprint as per ISO 14046.

    Parasites of parasites of bats: Laboulbeniales (Fungi: Ascomycota) on bat flies (Diptera: Nycteribiidae) in central Europe
    Haelewaters, Danny ; Pfliegler, Walter P. ; Szentiványi, Tamara ; Sándor, Attila D. ; Barti, Levente ; Camacho, Jasmin J. ; Gort, G. ; Estók, Péter ; Dick, Carl W. ; Pfister, Donald H. - \ 2017
    Harvard University
    Arthrorhynchus - bat flies - ecological specifity - ectoplastic fungi - host specificity - hyperparasitism
    Background Bat flies (Streblidae and Nycteribiidae) are among the most specialized families of the order Diptera. Members of these two related families have an obligate ectoparasitic lifestyle on bats, and they are known disease vectors for their hosts. However, bat flies have their own ectoparasites: fungi of the order Laboulbeniales. In Europe, members of the Nycteribiidae are parasitized by four species belonging to the genus Arthrorhynchus. We carried out a systematic survey of the distribution and fungus-bat fly associations of the genus in central Europe (Hungary, Romania). Results We encountered the bat fly Nycteribia pedicularia and the fungus Arthrorhynchus eucampsipodae as new country records for Hungary. The following bat-bat fly associations are for the first time reported: Nycteribia kolenatii on Miniopterus schreibersii, Myotis blythii, Myotis capaccinii and Rhinolophus ferrumequinum; Penicillidia conspicua on Myotis daubentonii; and Phthiridium biarticulatum on Myotis capaccinii. Laboulbeniales infections were found on 45 of 1,494 screened bat flies (3.0%). We report two fungal species: Arthrorhynchus eucampsipodae on Nycteribia schmidlii, and A. nycteribiae on N. schmidlii, Penicillidia conspicua, and P. dufourii. Penicillidia conspicua was infected with Laboulbeniales most frequently (25%, n = 152), followed by N. schmidlii (3.1%, n = 159) and P. dufourii (2.0%, n = 102). Laboulbeniales seem to prefer female bat fly hosts to males. We think this might be due to a combination of factors: female bat flies have a longer life span, while during pregnancy female bat flies are significantly larger than males and accumulate an excess of fat reserves. Finally, ribosomal DNA sequences for A. nycteribiae are presented. Conclusions We screened ectoparasitic bat flies from Hungary and Romania for the presence of ectoparasitic Laboulbeniales fungi. Arthrorhynchus eucampsipodae and A. nycteribiae were found on three species of bat flies. This study extends geographical and host ranges of both bat flies and Laboulbeniales fungi. The sequence data generated in this work contribute to molecular phylogenetic studies of the order Laboulbeniales. Our survey shows a complex network of bats, bat flies and Laboulbeniales fungi, of which the hyperparasitic fungi are rare and species-poor. Their host insects, on the other hand, are relatively abundant and diverse.
    Contrasting hydrologic response in the cuesta landscapes of Luxembourg
    Pfister, L. ; Hissler, C. ; Iffly, J.F. ; Coenders, M. ; Teuling, R. ; Arens, A. ; Cammeraat, L.H. - \ 2017
    In: The Luxembourg Gutland Landscape Springer International Publishing Switzerland - ISBN 9783319655413 - p. 73 - 87.
    The Attert River basin in Luxembourg is characterised by a large variety of clean and mixed physiogeographical settings (i.e. topography, soil types, land use, bedrock geology, etc.). This in turn generates manifold configurations of rainfall-runoff transformation processes. Here, we provide experimental data from more than a decade of hydro-meteorological observations carried out in a nested catchment set-up, and develop on past and ongoing research on fundamental hydrological functions of catchments: water collection, storage and release. In a first section, we detail the characteristics of the Attert River basin and a set of 9 nested sub-catchments. The second section provides insights into the seasonal and spatial variability of hydrological responses along a wide range of landuse, soil and bedrock settings. The analysis of double-mass curves between precipitation and discharge provided insights into how certain physiogeographic characteristics control hydrological responses. In the third section, we develop on dynamic catchment storage and how it differs between catchments with contrasted landuse and lithology. The fourth section provides insights into the spatial and temporal variability of forest canopy and forest floor storage capacity. Given the considerable amount of precipitation that is intercepted at annual scale, the process is likely to have a substantial influence on catchment storage dynamics.
    Exploring streamwater mixing dynamics via handheld thermal infrared imagery
    Antonelli, Marta ; Klaus, Julian ; Smettem, Keith ; Teuling, Ryan ; Pfister, Laurent - \ 2017
    Water 9 (2017)5. - ISSN 2073-4441
    Mixing dynamics - Stream confluence - Surface water - Thermal infrared imagery

    Stream confluences are important hotspots of aquatic ecological processes. Water mixing dynamics at stream confluences influence physio-chemical characteristics of the stream as well as sediment mobilisation and pollutant dispersal. In this study, we investigated the potential for handheld thermal infrared (TIR) imagery to provide rapid information on stream water mixing dynamics at small scales. In-situ visualisation of water mixing patterns can help reduce analytical errors related to stream water sampling locations and improve our understanding of how confluences and tributaries influence aquatic ecological communities. We compared TIR-inferred stream temperature distributions with water electrical conductivity and temperature (measured with a submerged probe) data from cross-channel transects. We show that the use of a portable TIR camera can enhance the visualisation of mixing dynamics taking place at stream confluences, identify the location of the mixing front between two different water sources and the degree of mixing. Interpretation of handheld TIR observations also provided information on how stream morphology and discharge can influence mixing dynamics in small streams. Overall, this study shows that TIR imagery is a valuable support technique for eco-hydrological investigation at small stream confluences.

    Parasites of parasites of bats : Laboulbeniales (Fungi: Ascomycota) on bat flies (Diptera: Nycteribiidae) in central Europe
    Haelewaters, Danny ; Pfliegler, Walter P. ; Szentiványi, Tamara ; Földvári, Mihály ; Sándor, Attila D. ; Barti, Levente ; Camacho, Jasmin J. ; Gort, Gerrit ; Estók, Péter ; Hiller, Thomas ; Dick, Carl W. ; Pfister, Donald H. - \ 2017
    Parasites & Vectors 10 (2017)1. - ISSN 1756-3305
    Arthrorhynchus - Bat flies - Ecological specificity - Ectoparasitic fungi - Host specificity - Hyperparasitism
    Background: Bat flies (Streblidae and Nycteribiidae) are among the most specialized families of the order Diptera. Members of these two related families have an obligate ectoparasitic lifestyle on bats, and they are known disease vectors for their hosts. However, bat flies have their own ectoparasites: fungi of the order Laboulbeniales. In Europe, members of the Nycteribiidae are parasitized by four species belonging to the genus Arthrorhynchus. We carried out a systematic survey of the distribution and fungus-bat fly associations of the genus in central Europe (Hungary, Romania). Results: We encountered the bat fly Nycteribia pedicularia and the fungus Arthrorhynchus eucampsipodae as new country records for Hungary. The following bat-bat fly associations are for the first time reported: Nycteribia kolenatii on Miniopterus schreibersii, Myotis blythii, Myotis capaccinii and Rhinolophus ferrumequinum; Penicillidia conspicua on Myotis daubentonii; and Phthiridium biarticulatum on Myotis capaccinii. Laboulbeniales infections were found on 45 of 1,494 screened bat flies (3.0%). We report two fungal species: Arthrorhynchus eucampsipodae on Nycteribia schmidlii, and A. nycteribiae on N. schmidlii, Penicillidia conspicua, and P. dufourii. Penicillidia conspicua was infected with Laboulbeniales most frequently (25%, n = 152), followed by N. schmidlii (3.1%, n = 159) and P. dufourii (2.0%, n = 102). Laboulbeniales seem to prefer female bat fly hosts to males. We think this might be due to a combination of factors: female bat flies have a longer life span, while during pregnancy female bat flies are significantly larger than males and accumulate an excess of fat reserves. Finally, ribosomal DNA sequences for A. nycteribiae are presented. Conclusions: We screened ectoparasitic bat flies from Hungary and Romania for the presence of ectoparasitic Laboulbeniales fungi. Arthrorhynchus eucampsipodae and A. nycteribiae were found on three species of bat flies. This study extends geographical and host ranges of both bat flies and Laboulbeniales fungi. The sequence data generated in this work contribute to molecular phylogenetic studies of the order Laboulbeniales. Our survey shows a complex network of bats, bat flies and Laboulbeniales fungi, of which the hyperparasitic fungi are rare and species-poor. Their host insects, on the other hand, are relatively abundant and diverse.
    On the potential for terrestrial diatom communities and diatom indices to identify anthropic disturbance in soils
    Antonelli, Marta ; Wetzel, Carlos E. ; Ector, Luc ; Teuling, Ryan ; Pfister, Laurent - \ 2017
    Ecological Indicators 75 (2017). - ISSN 1470-160X - p. 73 - 81.
    Bioindicators - Environmental control - Hydrological tracers - Luxembourg (Attert basin) - Soil diatoms - Soil quality

    A large amount of studies focuses on aquatic diatoms’ ecology and their use in the assessment of water quality. Little is known about terrestrial diatoms’ ecological behaviour and sensitivity to environmental factors. We hypothesise that terrestrial diatom communities can serve as a proxy of anthropic disturbance levels in terrestrial sites. To test our hypothesis, we apply an aquatic index to soil communities that is to deliver new information on the physiographic controls on soil diatoms. Diatom and soil samples were collected in the Attert River basin in Luxembourg during three seasons, in sites characterised by different combinations of geological, soil (schist, marl and sandstone) and land use (forest, grassland and agriculture) features. We found an effect of seasonality on soil diatom communities, reflected by different species dominance and abundances in samples during the three seasons. Soil pH and land use (which translates in a different amount of total carbon and nitrogen in soil) were identified as the variables having the largest impact in structuring the communities and as among the features with the highest importance in defining the ecological status of the sites (i.e. disturbed farmlands having higher pH and lower carbon and nitrogen content). However, the lack of information about the sensitivity of some of the most abundant terrestrial species in our study area caused some discrepancies between the expected (i.e. forested areas with low anthropic disturbance) and the obtained results, with several forested sites classified as having high anthropic disturbance. These results suggest that soil communities are likely to contain information about soil ecological status and highlight the importance of a better characterisation of terrestrial diatom species for developing a quality index based on soil communities.

    Global thermal pollution of rivers from thermoelectric power plants
    Raptis, C.E. ; Vliet, M.T.H. van; Pfister, S. - \ 2016
    Environmental Research Letters 11 (2016)10. - ISSN 1748-9318
    electricity generation - global - grid-based - heat emissions - once-through cooling - water temperature increase - water temperature model

    Worldwide riverine thermal pollution patterns were investigated by combining mean annual heat rejection rates from power plants with once-through cooling systems with the global hydrological-water temperature model variable infiltration capacity (VIC)-RBM. The model simulates both streamflow and water temperature on 0.5° ×0.5° spatial resolution worldwide and by capturing their effect, identifies multiple thermal pollution hotspots. The Mississippi receives the highest total amount of heat emissions (62% and 28% of which come from coal-fuelled and nuclear power plants, respectively) and presents the highest number of instances where the commonly set 3 °C temperature increase limit is equalled or exceeded. The Rhine receives 20% of the thermal emissions compared to the Mississippi (predominantly due to nuclear power plants), but is the thermally most polluted basin in relation to the total flow per watershed, with one third of its total flow experiencing a temperature increase ≥5 °C on average over the year. In other smaller basins in Europe, such as the Weser and the Po, the share of the total streamflow with a temperature increase ≥3 °C goes up to 49% and 81%, respectively, during July-September. As the first global analysis of its kind, this work points towards areas of high riverine thermal pollution, where temporally finer thermal emission data could be coupled with a spatially finer model to better investigate water temperature increase and its effect on aquatic ecosystems.

    Consensus building on the development of a stress-based indicator for LCA-based impact assessment of water consumption : outcome of the expert workshops
    Boulay, Anne Marie ; Bare, Jane ; Camillis, Camillo De; Döll, Petra ; Gassert, Francis ; Gerten, Dieter ; Humbert, Sebastien ; Inaba, Atsushi ; Itsubo, Norihiro ; Lemoine, Yann ; Margni, Manuele ; Motoshita, Masaharu ; Núñez, Montse ; Pastor, A.V. ; Ridoutt, Brad ; Schencker, Urs ; Shirakawa, Naoki ; Vionnet, Samuel ; Worbe, Sebastien ; Yoshikawa, Sayaka ; Pfister, Stephan - \ 2015
    The International Journal of Life Cycle Assessment 20 (2015)5. - ISSN 0948-3349 - p. 577 - 583.
    Consensus-based - Water consumption - WULCA

    Purpose: The WULCA group, active since 2007 on Water Use in LCA, commenced the development of consensus-based indicators in January 2014. This activity is planned to last 2 years and covers human health, ecosystem quality, and a stress-based indicator. This latter encompasses potential deprivation of both ecosystem and human, hence aiming to represent potential impacts more comprehensively than any other available LCA-oriented method assessing the “water scarcity footprint” (ISO 2014). Methods: A series of three expert workshops, including non-LCA experts from hydrology, eco-hydrology, and water supply science, was organized specifically on the topic of this generic midpoint indicator. They were held in Zurich on 10th September, in San Francisco on 5th October and in Tsukuba on 27th October 2014. In total 49 experts attended. The specific objectives of the workshops were twofold. First, it was to present the identified options of the stress-based indicator narrowed down by the active members of WULCA during the first 8 months of the project and to receive comments on the relevance, usefulness, acceptability, and focus of the selected indicator. Second, the workshop covered different challenges in the modeling of the indicator and presented the experts with background information and specific questions. This paper summarizes the discussions and outcome of these workshops. Where no agreement was reached, the working group of active members is considering all inputs received and continues the work. Results and discussion: The discussion covered first the question to be answered by such indicator, resulting on an agreement on the evaluation of the potential to deprive other users of water, independently of who the user is (i.e., human or ecosystems). Special attention was given to the special case of arid areas as well as the definition of environmental water requirements. Specific modeling challenges were then addressed: definition and quantification of human and ecosystem water demand, consideration of green water and terrestrial ecosystems, sources of data, distinction of groundwater and surface water, and temporal and geographical resolution. Conclusions: The input, decisions, and points of discussion were compiled and brought back within the group of active members. The group is using the recommendations and works further on the harmonization of the points of disagreement. It is expected that a selection of indicators representing different ways to address the most important issues will be produced and tested in spring 2015. The analysis of the result should lead to a provisional recommendation by summer 2015.

    Flow and transport modelling - Annex 2
    Zee, S.E.A.T.M. van der - \ 2013
    In: Model-driven soil probing, site assessment and evaluation - Guidance on technologies / Kästner, M., Braeckevelt, M., Döberl, G., Cassiani, G., Papini, M.P., Leven-Pfister, C., van Ree, D., Rome, Italy : Sapienza Università Editrice Publishers - ISBN 9788895814728 - p. 283 - 287.
    Poisoning by plants, mycotoxins and related toxins
    Raamsdonk, L.W.D. van - \ 2012
    World Mycotoxin Journal 5 (2012). - ISSN 1875-0710 - p. 103 - 104.
    Edited By: F. Riet-Correa, J. Pfister, A.L. Schild, T.L. Wierenga
    Rainfall estimation with microwave links: a substitute for rain gauges? Results from a long-term experiment in Luxembourg-City
    Fenicia, F. ; Pfister, L. ; Iffly, J.F. ; Kavetski, D. ; Uijlenhoet, R. - \ 2012
    Microwave links for rainfall estimation in urban environment: insights from an experimental setup in Luxembourg city
    Fenicia, F. ; Pfister, L. ; Kavetski, D. ; Matgen, P. ; Iffly, J.F. ; Hoffman, L. ; Uijlenhoet, R. - \ 2012
    Journal of Hydrology 464-465 (2012). - ISSN 0022-1694 - p. 69 - 78.
    path-averaged rainfall - dual-frequency - attenuation - resolution - fields - gauges - radar
    Although the theoretical aspects of rainfall monitoring through microwave links are quite well established, only few practical applications have evaluated this technique in an operational setting. Microwave links are of particular interest in urban areas, where high frequency measurements are needed due to the fast hydrological response of the system, and link networks are usually already in-place. This study presents the first results of an on-going experiment in Luxembourg-City, which includes two dual-frequency links and several rain gauges at intermediate locations along the links. The experimental set-up allows comparing rain rate estimates based on the individual frequencies as well as estimates based on the difference between the two frequencies. We compared several models for expressing the relationship between attenuation and rain rate, including different baseline estimation methods such as the traditional constant-baseline model and a one-parameter model based on a first order low-pass filter. The models were evaluated using a Bayesian approach and subjected to posterior scrutiny based on several diagnostics. In contrast to previous research, our results indicated that estimates based on the attenuation difference appeared poorer than the estimates based on individual frequencies. The one-parameter baseline estimation method provided consistently better results than the traditional constant-baseline method, which justifies the increased model complexity. Uncertainty of model predictions was relatively large for low intensity rainfall, which highlights one of the limitations of this technique. Models were validated in different periods and on different links, in some cases demonstrating large bias. Model parameters were generally well-identifiable, though uncertainty in the rainfall predictions appeared under-estimated in some cases.
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