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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    Exploitation or eutrophication as threats for fisheries? Social and ecological drivers of ecosystem changes in Lake Victoria
    Zwieten, P.A.M. van; Peter, H.K. ; Medard Ntara, M. ; Cornelissen, I.J.M. ; Downing, A.S. ; Nagelkerke, L.A.J. ; Mooij, W.M. ; Dijk, H. van - \ 2012
    Lake Victoria is the second largest freshwater lake and supports the largest freshwater commercial fishery in the world. Eutrophication and fisheries drive Lake Victoria’s changing ecosystem with far-reaching consequences for exploitation patterns, livelihoods and trade. The SEDEC research program attempts to link the two processes to understand feedbacks in food webs, resource use patterns and trade. Our main objective is to unravel the social and ecological drivers of ecosystem change and to develop longterm strategies to deal with the risks of these ecosystem changes. The working hypothesis is that continued eutrophication presents a much graver risk to the resource base and livelihoods of coastal populations than fishing pressure. Initially eutrophication resulted in a higher carrying capacity for Nile perch, because food availability increased through enhanced primary production. This increased carrying capacity resulted in an apparent resilience of the exploited Nile perch stocks to increased fishing pressure. However, the compensation of increased fishing pressure by increased production could fail when eutrophication becomes too strong, because of increasing self-shading by algae and by an increasing anoxic hypolimnion, which can cause catastrophic fish kills. Optimal nutrient concentrations to support fisheries may have already been exceeded, which could negatively affect Nile perch biomass. The responses of the fishery to changes caused by increased eutrophication as well as the responses of Nile perch stocks to the combined impacts of size selective fishing and eutrophication are researched in four inter-related projects that (1) analyse social factors that drive decision-making processes of individuals in the fishery; (2) analyse ecological factors, including size-selection, that drive decisions about spatial effort allocation by fishermen; (3) analyse the impact of eutrophication and Nile perch predation on food web structure, and (4) model the interactions and feedbacks resulting from eutrophication and fishery, as most likely factors driving changes in Lake Victoria’s food web. Scenarios to assess management under non-steady state conditions are developed in collaboration with international scientific experts and with regional and national government and research institutions.
    Collapse and reorganization of a food web of Mwanza Gulf, Lake Victoria
    Downing, A.S. ; Nes, E.H. van; Janse, J. ; Witte, F. ; Cornelissen, I.J.M. ; Scheffer, M. ; Mooij, W.M. - \ 2012
    Ecological Applications 22 (2012)1. - ISSN 1051-0761 - p. 229 - 239.
    african great-lakes - nile perch - morphological-changes - lates-niloticus - east-africa - fish - biodiversity - challenges - fisheries - predator
    Lake Victoria (in East Africa) is the world's second largest fresh-water system. Over the past century the ecosystem has undergone drastic changes. Some 30 years after the introduction of Nile perch and tilapia in the 1950s, the highly diverse community of native haplochromines collapsed, leaving a system dominated by only four species: the native cyprinid dagaa and shrimp Caridina nilotica, as well as the introduced Nile perch and Nile tilapia. More recently, an unexpected resurgence of haplochromines has been reported. To better grasp these changes in terms of ecosystem functioning and of changes in growth of trophic groups, we created mass-balances of the food web near Mwanza (Tanzania) before, during and after the Nile perch boom (1977, 1987 and 2005), using the application ECOPATH. We connected these mass-balances with a dynamic model assuming linear trends in net growth rates of the trophic groups. Our analysis suggests that the Nile perch boom initially altered the biomass distribution over trophic levels. Also, results indicate that not only fishing but also changes at the detritivores' trophic level might have played an important role in driving changes in the system. Both the mass-balances and the dynamic model connecting them reveal that after a major distortion during the Nile perch boom, the biomass distribution over the main trophic levels had largely recovered to its original state by 2005. However, no such return appeared in terms of community structure. Biodiversity in the new state is dramatically lower, consisting of introduced species and a few native surviving species. We conclude that at an aggregate level Lake Victoria's ecosystem has proved to be resilient in the sense that its overall trophic structure has apparently recovered after a major perturbation. By contrast, its intricate functional structure and associated biodiversity have proven to be fragile and seem unlikely to recover
    Challenges and opportunities for integrating lake ecosystem modelling approaches
    Mooij, W.M. ; Trolle, D. ; Jeppesen, E. ; Arhonditsis, G. ; Belolipetsky, P.V. ; Chitamwebwa, D.B.R. ; Degermendzhy, A.G. ; DeAngelis, D.L. ; Domis, L.N.D. ; Downing, A.S. ; Elliott, J.A. ; Fragoso, C.R. ; Gaedke, U. ; Genova, S.N. ; Gulati, R.D. ; Hakanson, L. ; Hamilton, D.P. ; Hipsey, M.R. ; Hoen, J. 't; Hulsmann, S. ; Los, F.H. ; Makler-Pick, V. ; Petzoldt, T. ; Prokopkin, I.G. ; Rinke, K. ; Schep, S.A. ; Tominaga, K. ; Dam, A.A. van; Nes, E.H. van; Wells, S.A. ; Janse, J.H. - \ 2010
    Aquatic Ecology 44 (2010)3. - ISSN 1386-2588 - p. 633 - 667.
    fresh-water ecosystems - of-the-art - daphnia population-dynamics - trophic state indicators - predator-prey system - causes regime shifts - library salmo-oo - shallow lakes - climate-change - submerged macrophytes
    A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others ('reinventing the wheel'). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available ('having tunnel vision'). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and traitbased models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its 'leading principle', there are many opportunities for combining approaches. We take the point of view that a single 'right' approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view on the functioning of lake ecosystems. We end with a set of specific recommendations that may be of help in the further development of lake ecosystem models.
    Global desertification: building a science for dryland development
    Reynolds, J.F. ; Smith, D.M.S. ; Lambin, E.F. ; Turner, B.L. ; Mortimore, M. ; Batterbury, S.P.J. ; Downing, T.E. ; Dowlatabadi, H. ; Fernandez, R.J. ; Herrick, J.E. ; Huber-Sannwald, E. ; Jiang, H. ; Leemans, R. ; Lynam, T. ; Maestre, T. ; Ayarza, M. ; Walker, B. - \ 2007
    Science 316 (2007)5826. - ISSN 0036-8075 - p. 847 - 851.
    sustainability - vulnerability - africa - challenges - feedbacks - knowledge - lessons - ecology - commons - systems
    In this millennium, global drylands face a myriad of problems that present tough research, management, and policy challenges. Recent advances in dryland development, however, together with the integrative approaches of global change and sustainability science, suggest that concerns about land degradation, poverty, safeguarding biodiversity, and protecting the culture of 2.5 billion people can be confronted with renewed optimism. We review recent lessons about the functioning of dryland ecosystems and the livelihood systems of their human residents and introduce a new synthetic framework, the Drylands Development Paradigm (DDP). The DDP, supported by a growing and well-documented set of tools for policy and management action, helps navigate the inherent complexity of desertification and dryland development, identifying and synthesizing those factors important to research, management, and policy communities.
    Transition to adaptive water management: the NeWater Project
    Pahl-Wostl, C. ; Downing, T. ; Kabat, P. ; Magnuszewksi, P. ; Meigh, J. ; Schlueter, M. ; Sendizimir, J. ; Werners, S.E. - \ 2005
    Osnabrück : Institute of Environmental Systems Research, University of Osnabrück (NeWater working paper 1)
    waterbeheer - klimaatverandering - water management - climatic change
    The European background database
    Posch, M. ; Reinds, G.J. ; Slootweg, J. - \ 2003
    In: Modelling and mapping of critical thresholds in Europe: CCE status report 2003 / Posch, M., Hettelingh, J.P., Slootweg, J., Downing, R.J., Bilthoven : RIVM (RIVM Report 259101013) - ISBN 9789069601069 - p. 37 - 44.
    What are the key dimensions at the international scale?
    Lambin, E.F. ; Chasek, P.S. ; Downing, T.E. ; Kerven, C. ; Kleidon, A. ; Leemans, R. ; Lüdeke, M. ; Prince, S.D. ; Xue, Y. - \ 2003
    In: Integrated Assessment and Desertification / Stafford Smith, D.M., Reynolds, J.F., Berlin : Dahlem University Press - ISBN 9783934504103 - p. 387 - 402.
    Critical loads of lead and cadmium for European forest soils
    Reinds, G.J. ; Vries, W. de; Groenenberg, B.J. - \ 2001
    In: Modelling and mapping of critical thresholds in Europe: status report 2001. Bilthoven, RIVM, 2001. RIVM Rep. 259101010 / Posch, M., de Smet, P.A.M., Hettelingh, J.P., Downing, R.J., - p. 81 - 92.
    bodemchemie - bos - milieu - zware metalen - Europa
    Dynamic modelling and the calculation of critical loads for biodiversity
    Hinsberg, A. van; Kros, H. - \ 2001
    In: Modelling and mapping of critical thresholds in Europe: status report 2001. Bilthoven, RIVM, 2001. RIVM Rep. 259101010 / Posch, M., de Smet, P.A.M., Hettelingh, J.P., Downing, R.J., - p. 73 - 80.
    atmosferische depositie - biodiversiteit - milieu - natuurbehoud - nutriënten - verzuring
    Modelling climate change on potato in central England
    Wolf, J. - \ 2000
    In: Climate Change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 239 - 261.
    Modelling climate change impact on soya bean in south-west Spain
    Wolf, J. - \ 2000
    In: Climate Change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 217 - 237.
    Modelling climate change impact at the site scale on potato
    Wolf, J. - \ 2000
    In: Climate change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 135 - 154.
    Modelling climate change impacts at the site scale on C and N dynamics
    Wolf, J. - \ 2000
    In: Climate change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 103 - 116.
    Quantification of uncertainty in climate change impact assessment
    Downing, T.E. ; Barrow, E.M. ; Brooks, R.J. ; Butterfield, R.E. ; Carter, T.R. ; Harisson, P.A. ; Hulme, M. ; Oleson, J.E. ; Porter, J.R. ; Schellberg, J. ; Semenov, M.A. ; Vinther, F.P. ; Wheeler, T.R. ; Wolf, J. - \ 2000
    In: Climate Change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 435 - 441.
    Review and comparison of scaling-up methods
    Butterfield, R.E. ; Bindi, M. ; Brooks, R.J. ; Carter, T.R. ; Delecolle, R. ; Downing, T.E. ; Harnos, Z. ; Harrison, P.A. ; Iglesias, A. ; Olesen, J.E. ; Orr, J.L. ; Semenov, M.A. ; Wolf, J. - \ 2000
    In: Climatic Change, Climatic Variability and Agriculture in Europe / Downing, T.E., Harrison, P.A., Butterfield, R.E., Lonsdale, K.G., Oxford, UK : Environmental Change Institute - ISBN 9781874370222 - p. 393 - 414.
    Modelling climate change impacts on potato in Central England.
    Wolf, J. - \ 1997
    In: Climate change, climatic variability and agriculture in Europe / Butterfield, R.E., Lonsdale, K.G., Downing, T.E., Oxford, UK : University of Oxford - p. 177 - 197.
    Modelling climate change impacts on soya bean in a region of Spain.
    Wolf, J. - \ 1997
    In: Climate change, climatic variability and agriculture in Europe / Butterfield, R.E., Lonsdale, K.G., Downing, T.E., Oxford, UK : University of Oxford - p. 157 - 176.
    Modelling climate change impacts at the site scale on potato.
    Wolf, J. - \ 1997
    In: Climate change, climatic variability and agriculture in Europe / Butterfield, R.E., Lonsdale, K.G., Downing, T.E., Oxford, UK : University of Oxford - p. 113 - 130.
    Modelling climate change impacts at the site scale on soya bean.
    Wolf, J. - \ 1997
    In: Climate change, climatic variability and agriculture in Europe / Butterfield, R.E., Lonsdale, K.G., Downing, T.E., Oxford, UK : University of Oxford - p. 81 - 95.
    Methods to calculate critical loads for heavy metals and persistent organic pollutants
    Vries, W. de; Bakker, D.J. - \ 1995
    In: Calculation and mapping of critical thresholds in Europe: status report 1995 / Posch, M., de Smet, P.A.M., Hettelingh, J.P., Downing, R.J., - p. 77 - 81.
    Basic principles of methods for calculating critical loads of the heavy metals lead, cadmium, copper, zinc, nickel, chromium and mercury and persistent organic pollutants (POPs) for soils and surface waters are described briefly. The methods are basedon the implicit assumption that environmental quality criteria do exist for the metals and POPs. The computation models described are based on the concept of equilibrium partitioning between dissolved and adsorbed phases in homogeneously mixed soil, surface water and sediment compartments in a steady-state situation. The various sources of uncertainty inherent in the various assumptions are discussed in detail.
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