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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Vision principles for harvest robotics : sowing artificial intelligence in agriculture
Barth, Ruud - \ 2018
Wageningen University. Promotor(en): Eldert van Henten, co-promotor(en): Jochen Hemming. - Wageningen : Wageningen University - ISBN 9789463433181 - 325
cum laude
Creation of fibrous plant protein foods
Dekkers, Birgit L. - \ 2018
Wageningen University. Promotor(en): Atze Jan van der Goot; Remko Boom. - Wageningen : Wageningen University - ISBN 9789463433198 - 204
cum laude
Encapsulation of lipids to delay lipolysis and reduce food intake
Corstens, Meinou N. - \ 2018
Wageningen University. Promotor(en): Karin Schroen; A.A.M. Masclee, co-promotor(en): Claire Berton-Carabin; F.J. Troost. - Wageningen : Wageningen University - ISBN 9789463432382 - 200
cum laude
Cryptosporidium in rivers of the world: the GloWPa-Crypto model
Vermeulen, Lucie C. - \ 2018
Wageningen University. Promotor(en): Carolien Kroeze, co-promotor(en): Nynke Hofstra. - Wageningen : Wageningen University - ISBN 9789463438209 - 236
cum laude

Diarrhoeal disease is very common around the world. Knowing more about the global burden of diarrhoeal disease and about the geographical distribution of pathogen pollution is important for decision making and water and sanitation planning. The objective of this thesis is to increase knowledge on the sources, fate and transport of Cryptosporidium in rivers worldwide using spatially explicit modelling. I present the Global Waterborne Pathogen model for Cryptosporidium (GloWPa-Crypto), the first global model of waterborne pathogen emissions to and concentrations in rivers. The model is used to provide information on pathogen concentrations in data-sparse regions, identify hotspot regions, identify the relative contribution of different sources, and in scenario analysis to study the impacts of global change or management strategies. Furthermore, the model can be applied in the analysis of risk, burden of disease and health-based treatment targets, and make a valuable contribution in meeting the Sustainable Development Goals.

The art of being small : brain-body size scaling in minute parasitic wasps
Woude, Emma van der - \ 2017
University. Promotor(en): Marcel Dicke, co-promotor(en): Hans Smid. - Wageningen : Wageningen University - ISBN 9789463436564 - 231
brain - insects - neurons - scaling - cognitive development - vespidae - parasitoid wasps - cum laude - hersenen - insecten - neuronen - schaalverandering - cognitieve ontwikkeling - sluipwespen

Haller’s rule states that small animals have relatively larger brains than large animals. This brain-body size relationship may enable small animals to maintain similar levels of brain performance as large animals. However, it also causes small animals to spend an exceptionally large proportion of energy on the development and maintenance of energetically expensive brain tissue. The work that is presented in this thesis reveals how the smallest animals face the challenge to maintain ecologically required levels of cognitive performance, while being limited by small numbers of neurons and a restricted energy balance. Developing into a small adult has cognitive costs for the parasitic wasp Nasonia vitripennis, and relative brain size is strongly constrained in this species. The extremely small parasitic wasp Trichogramma evanescens forms an exception to Haller’s rule by showing isometric brain-body size scaling. Miniaturized insect species may apply this strategy to avoid the excessive energetic costs of relatively large brains, thereby achieving smaller brain and body sizes than would be possible in the situation that is described by Haller’s rule. This brain-scaling strategy does not result in affected memory performance of small T. evanescens compared to larger individuals, and appears to be facilitated by a large flexibility in the size of neural components, rather than in their number or structural complexity. Maintaining neural complexity may the underlying mechanism that maintains the cognitive abilities of the smallest brains, possibly at the cost of reduced longevity as a consequence of the small size of neuronal cell bodies. This strategy could form the art of being small.

Rural livelihoods and agricultural commercialization in colonial Uganda: conjunctures of external influences and local realities
Haas, Michiel A. de - \ 2017
University. Promotor(en): Ewout Frankema, co-promotor(en): Niek Koning. - Wageningen : Wageningen University - ISBN 9789463436281 - 250
cum laude - livelihoods - livelihood strategies - communities - rural areas - farmers - history - colonies - colonialism - income - gender - social inequalities - food crops - cash crops - uganda - east africa - middelen van bestaan - strategieën voor levensonderhoud - gemeenschappen - platteland - boeren - geschiedenis - kolonies - kolonialisme - inkomen - geslacht (gender) - sociale ongelijkheden - voedselgewassen - marktgewassen - oost-afrika

The economic history of Sub-Saharan Africa is characterized by geographically and temporally dispersed booms and busts. The export-led ‘cash-crop revolution’ in parts of Sub-Saharan Africa during the colonial era is a key example of an economic boom. This thesis examines how external influences and local realities shaped the nature, extent and impact of the ‘cash-crop revolution’ in colonial Uganda, a landlocked country in central east Africa, where cotton and coffee production for global markets took off following completion of a railway to the coast. The thesis consists of five targeted ‘interventions’ into contemporary debates of comparative African development. Each of these five interventions is grounded in the understanding that the ability of rural Africans to respond to and benefit from trade integration during the colonial era was mediated by colonial policies, resource endowments and local institutions.

The first chapter reconstructs welfare development of Ugandan cash-crop farmers. Recent scholarship on historical welfare development in Sub-Saharan Africa has uncovered long-term trends in standards of living. How the majority of rural dwellers fared, however, remains largely elusive. This chapter presents a new approach to reconstructing rural living standards in a historical context, building upon the well-established real wage literature, but moving beyond it to capture rural realities, employing sub-national rural survey, census, and price data. The approach is applied to colonial and early post-colonial Uganda (1915–70), and yields a number of findings. While an expanding smallholder-based cash-crop sector established itself as the backbone of Uganda’s colonial economy, farm characteristics remained largely stagnant after the initial adoption of cash crops. Smallholders maintained living standards well above subsistence level, and while the profitability of cash crops was low, their cultivation provided a reliable source of cash income. At the same time, there were pronounced limits to rural welfare expansion. Around the time of decolonization, unskilled wages rose rapidly while farm incomes lagged behind. As a result, an urban–rural income reversal took place. The study also reveals considerable differences within Uganda, which were mediated to an important extent by differential resource endowments. Smallholders in Uganda’s banana regions required fewer labour inputs to maintain a farm income than their grain-farming counterparts, creating opportunities for additional income generation and livelihood diversification.

The second chapter zooms in on labour migration which connected Belgian-controlled Ruanda-Urundi to British-controlled Buganda, the central province of Uganda on the shores of Lake Victoria. The emergence of new labour mobility patterns was a key aspect of economic change in colonial Africa. Under conditions of land abundance and labour scarcity, the supply of wage labour required either the ‘pull’ forces of attractive working conditions and high wages, or the ‘push’ forces of taxation and other deliberate colonial interventions. Building upon primary sources, I show that this case diverges from the ‘conventional’ narrative of labour scarcity in colonial Africa. I argue that Ruanda-Urundi should be regarded as labour abundant and that migrants were not primarily ‘pushed’ by colonial labour policies, but rather by poverty and limited access to agricultural resources. This explains why they were willing to work for low wages in Buganda. I show that African rural employers were the primary beneficiaries of migrant labour, while colonial governments on both sides of the border were unable to control the course of the flow. As in the first chapter, this chapter highlights that the effects of trade integration on African rural development were uneven, and mediated by differences in resource endowments, local institutions and colonial policies.

The third chapter zooms out of the rural economy, evaluating the broader opportunity structures faced by African men and women in Uganda, and discussing the interaction of local institutions and colonial policies as drivers of uneven educational and occupational opportunities. The chapter engages with a recent article by Meier zu Selhausen and Weisdorf (2016) to show how selection biases in, and Eurocentric interpretations of, parish registers have provoked an overly optimistic account of European influences on the educational and occupational opportunities of African men and women. We confront their dataset, drawn from the marriage registers of the Anglican Cathedral in Kampala, with Uganda’s 1991 census, and show that trends in literacy and numeracy of men and women born in Kampala lagged half a century behind those who wedded in Namirembe Cathedral. We run a regression analysis showing that access to schooling during the colonial era was unequal along lines of gender and ethnicity. We foreground the role of Africans in the spread of education, argue that European influences were not just diffusive but also divisive, and that gender inequality was reconfigured rather than eliminated under colonial rule. This chapter also makes a methodological contribution. The renaissance of African economic history in the past decade has opened up new research avenues to study the long-term social and economic development of Africa. We show that a sensitive treatment of African realities in the evaluation of European colonial legacies, and a critical stance towards the use of new sources and approaches, is crucial.

The fourth chapter singles out the role of resource endowments in explaining Uganda’s ‘cotton revolution’ in a comparative African perspective. Why did some African smallholders adopt cash crops on a considerable scale, while most others were hesitant to do so? The chapter sets out to explore the importance of factor endowments in shaping the degrees to which cash crops were adopted in colonial tropical Africa. We conduct an in-depth case study of the ‘cotton revolution’ in colonial Uganda to put the factor endowments perspective to the test. Our empirical findings, based on an annual panel data analysis at the district-level from 1925 until 1960, underscore the importance of Uganda’s equatorial bimodal rainfall distribution as an enabling factor for its ‘cotton revolution’. Evidence is provided at a unique spatial micro-level, capitalizing on detailed household surveys from the same period. We demonstrate that previous explanations associating the variegated responses of African farmers to cash crops with, either the role of colonial coercion, or the distinction between ‘forest/banana’ and ‘savannah/grain’ zones, cannot explain the widespread adoption of cotton in Uganda. We argue, instead, that the key to the cotton revolution were Uganda’s two rainy seasons, which enabled farmers to grow cotton while simultaneously pursuing food security. Our study highlights the importance of food security and labour seasonality as important determinants of uneven agricultural commercialization in colonial tropical Africa.

The fifth and final chapter further investigates the experience of African smallholders with cotton cultivation, providing a comparative explanatory analysis of variegated cotton outcomes, focusing in particular on the role of colonial and post-colonial policies. The chapter challenges the widely accepted view that (i) African colonial cotton projects consistently failed, that (ii) this failure should be attributed to conditions particular to Africa, which made export cotton inherently unviable and unprofitable to farmers, and that (iii) the repression and resistance often associated with cotton, all resulted from the stubborn and overbearing insistence of colonial governments on the crop per se. I argue along three lines. Firstly, to show that cotton outcomes were diverse, I compare cases of cotton production in Sub-Saharan Africa across time and space. Secondly, to refute the idea that cotton was a priori unattractive, I argue that the crop had substantial potential to connect farmers to markets and contribute to poverty alleviation, particularly in vulnerable, marginal and landlocked areas. Thirdly, to illustrate how an interaction between local conditions and government policies created conducive conditions for cotton adoption, I zoom in on the few yet significant ‘cotton success stories’ in twentieth century Africa. Smallholders in colonial Uganda adopted cotton because of favourable ecological and marketing conditions, and policies had an auxiliary positive effect. Smallholders in post-colonial Francophone West Africa faced much more challenging local conditions, but benefitted from effective external intervention and coordinated policy. On a more general level, this chapter demonstrates that, from a perspective of rural development, colonial policies should not only be seen as overbearing and interventionist, but also as inadequate, failing to aid rural Africans to benefit from new opportunities created by trade integration.

Amphibious anthropology : engaging with maritime worlds in Indonesia
Pauwelussen, Annet P. - \ 2017
University. Promotor(en): Leontine Visser, co-promotor(en): Gerard Verschoor. - Wageningen : Wageningen University - ISBN 9789463430654 - 208
cum laude

This thesis explores how people live amphibiously in dynamic land-sea environments. It is based on eighteen months of ethnographic fieldwork (2011 – 2013) in the Makassar Strait maritime region in Indonesia: a complex and amphibious land-sea interface. In Western science little attention is given to how people live at sea. There is a general land bias, by which people are seen as primarily belonging to the land. Yet people do live at sea, or rather: in these dynamic land-sea environments. Engaging with these mobile and sea-based ways of life of maritime people provides not only a fuller understanding of how people relate to their environment, but , essentially, it also enables a critical reflection of land-biased assumptions in science and society.

Anthropology, with its qualitative research methods is particularly suitable to do such in-depth and long-term engagement with other worlds. The research on which the thesis is based was carried out as a mobile ethnography, following people seawards, travelling with them for days to visit close family on faraway islands or joining them on their fishing and diving trips, including illegal fishers using bombs and cyanide poison on coral reefs. Also followed were the practices of marine conservation staff, as they organised field trips to fishing communities. These travels – described in the thesis – show how islands and marine spaces that are remote from the land, turn out to be regional hubs of oversees trade and family relations. From a sea-based perspective the Makassar Strait is a continuity of relations and movements flanked by land masses. This inverts the land-based perspective of the sea as an extension of the land by putting the sea centre stage.

The Makassar Strait figures in this thesis as an active and moving world – or worlds – of human-marine relations to learn from and theorise about the notion of ontological flow: fluidity of being and moving in relation. Flow is both movement as a pattern of activity – the flowing – and that what flows; elements, matter and meaning in motion. The notion of worlds in flow has infused recent ontological debates in anthropological theory in which reality is assumed contingent, fluid and multiple – thereby revitalising the philosophical work of earlier thinkers, among whom Michel Serres and Gilles Deleuze. This way of thinking complexity and ontological fluidity is central to literature that has emerged out of the cross-fertilisation of Science and Technology Studies (STS), anthropology and philosophy. Despite differences, these studies share the objective to follow, engage with and translate how, in practice, material and semiotic realities come to be and matter – instead of developing a way to ‘access reality better’.

The concept of ‘amphibiousness’ is mobilised to refer to living in and moving between different worlds that can intermingle but that cannot be reduced to each other. The concept is used to describe the human capacity to live in different worlds at the same time. This amphibious capacity is further elaborated 1) in terms of living in a hybrid land-water interface, 2) in terms of being able to move along with different understandings of the world, of reality, and 3) It refers to the methodology of the anthropologist who also needs to move in these worlds bodily and cognitively, to develop a sensitivity to and understanding of these different worlds. Amphibiousness captures the anthropological engagement with flow, multiplicity and otherness by way of moving between worlds in order to explore the moving interface between worlds, realities or ways of life that partly interact. The research question: How to grasp flow – the fluctuations of and between bodies, things or worlds in the making - conceptually and methodologically without reducing its vital mobility and fluidity? is elaborated in a methodological Chapter 2, and three research chapters (Chapter 3, Chapter 4, and Chapter 5) that each focus from a different angle on human-marine relations.

The research exposes fundamentally different, and sometimes conflicting, ways in which people understand and experience their relation to the sea. These were not just different perspectives on one maritime reality, or world. These were inherently different understandings of reality, and different ways in which this reality is put into practice, in which worlds – plural – are being created and sustained. In anthropology we speak of ontological difference, because it concerns with (radically) different notions of wat exists, what is real, what matters and what entities participate in the reproduction of the world.

Although these worlds are different – they cannot be reduced to each another - they are also not separated in any clear-cut way. They do flow into each other, as people, objects and ideas can amphibiously move in between. It is argued in this thesis that such amphibious translation is essential for more effective and equal collaboration in marine conservation. International environmental organisations insufficiently acknowledge (radically) different ways of doing and thinking human-marine relations. Disregarding these undermines the viability of conservation programs as it repeatedly leads to clashes between different ways in which maritime worlds are understood and organised in practice. To be effective, marine conservation needs to become amphibious; attentive to fundamentally different ways of understanding and experiencing the relationship between people and the sea, as well as the mobile practices of trade, fishing, travel and family affiliations through which these worlds are shaped beyond the borders of marine reserves.

Chapter 2 intends to answer the question how to grasp environmental otherness – radically different ways of understanding and experiencing human-marine relations – in and through ethnography. Chapter 3 serves to provide some empirical grounding to show the relevancy and urgency of a paradigmatic shift in conservation thinking, finding ways to engaging mobile maritime people like the Bajau. The solution to the ‘participation problem’ in conservation will not lie in developing ways to make local people participate more in Western conservation schemes. What is needed is an ontological shift in conservation thinking itself. Chapter 4 describes a conservation outreach project that attempts to educate and convert local people into coral protectors. Both coral and the sea-dwelling Bajau people appear to be amphibious beings, moving between a changeable land-water interface, and between different, fluidly interwoven ontological constellations. Failure of conservation organisations to recognise the ontologically ambiguous nature of ‘coral’ and ‘people’ translates to a breakdown of outreach goals. Chapter 5 provides a case study of a dangerous and destructive fishing practice (cyanide fishing) by which fishers dive beyond the limits of what their body can take – and spirits allow, a practice that generates feeling of both fear and enjoyment as they experience a process of becoming permeable to fluids, spirits and currents penetrating or leaking out of their bodies. This chapter exposes how cyanide fishing sustains as a way of life, involving and producing affective relations.

In Chapter 6 it is concluded how ontological multiplicity is of a heuristic and political relevance to social science, and anthropology in particular because it allows us to engage with radical difference – or the real on different terms – instead of explaining it away in our own terms. Engaging with such radical different is important because it allows to see the realities that systematically escape (scholarly) attention, yet affect the world nonetheless. This requires translation – the practice of relating different worlds, reals, repertoires or ways of life and bringing them into interaction – which is a process of, and a condition for, dialogue. The notion of amphibiousness has practical and political value, in particular for reconsidering conservation and development outreach and how it may be reframed as a process involving ontological dialogue. Providing room for ambiguity, thinking with amphibiousness furthermore encourages suspension of the (Western) tendency to explain the Other, to fix what does not add up.

River export of nutrients to the coastal waters of China: the MARINA model to assess sources, effects and solutions
Strokal, Maryna - \ 2016
University. Promotor(en): Carolien Kroeze, co-promotor(en): S. Luan; Lin Ma. - Wageningen : Wageningen University - ISBN 9789462579729 - 226
cum laude - nutrients - rivers - coastal water - models - eutrophication - coastal areas - water pollution - china - voedingsstoffen - rivieren - kustwateren - modellen - eutrofiëring - kustgebieden - waterverontreiniging

Rivers export increasing amounts of nitrogen (N) and phosphorus (P) to the coastal waters of China. This causes eutrophication problems that can damage living organisms when oxygen levels drop and threaten human health through toxic algae. We know that these problems result from human activities on land such as agriculture and urbanization. However, the relative importance of these human activities for river export of nutrients to Chinese seas is not well studied. There are two important issues that need further investigation: the relative importance of upstream pollution on downstream impacts and the relative importance of typical sources of nutrients in Chinese rivers that are often ignored in existing modeling studies.

My PhD thesis, therefore, aims to better understand trends in river export of nutrients to the coastal waters of China by source from sub-basins, and the associated coastal eutrophication. To this end, I developed the MARINA model: Model to Assess River Inputs of Nutrients to seAs. For this, I used the existing Global NEWS-2 model (Nutrient Export from WaterSheds) as a starting point.

I formulated five sub-objectives to achieve the main objective:

To analyze the original Global NEWS-2 model for river export of nutrients and the associated coastal eutrophication (Chapter 2);

To develop a sub-basin scale modeling approach to account for impacts of upstream human activities on downstream water pollution, taking the Pearl River as an example (Chapter 3);

To quantify the relative share of manure point sources to nutrient inputs to rivers at the sub-basin scale (Chapter 4);

To quantify the relative share of sources to river export of nutrients at the sub-basin scale (Chapter 5);

To explore optimistic futures to reduce river export of nutrients and coastal eutrophication in China (Chapter 6).

The study area includes rivers draining roughly 40% of China. This includes the most densely populated areas, and areas with intensive economic activities. The rivers include the Yangtze (Changjiang), Yellow (Huanghe), Pearl, Huai, Hai and Liao. In the MARINA model, the drainage areas of the large Yangtze, Yellow and Pearl rivers are divided into up-, middle- and downstream sub-basins. The principle of the sub-basin approach of MARINA is that nutrients from human activities are transported by tributaries to outlets of sub-basins and then to the river mouth (coastal waters) through the main channel. The model takes into account nutrients that are partly lost or retained during transport towards the river mouth. The model quantifies river export of nutrients by source from sub-basins for 1970, 2000 and 2050.

The main six findings of the MARINA results for China are:

Finding 1: Dissolved N and P export by Chinese rivers increased by a factor of 2-8 between 1970 and 2000;

Finding 2: The potential for coastal eutrophication was low in 1970 and high in 2000 in China;

Finding 3: Most dissolved N and P in Chinese seas is from middlestream and downstream human activities;

Finding 4: Manure point sources are responsible for 20-80% of dissolved N and P in Chinese rivers;

Finding 5: In the future, river export of nutrients may increase in the Global Orchestration (GO) scenario of the Millennium Ecosystem Assessment. Current policy plans (CP scenario) may not sufficient to avoid this increase;

Finding 6: In optimistic scenarios (OPT-1 and OPT-2), the potential for coastal eutrophication is low in 2050, mainly as a result of assumed full implementation of: (1) high recycling rates of animal manure (OPT-1 and OPT-2), and (2) high efficiencies of nutrient removal in sewage systems (OPT-2, see Figure 1).

Figure 1. Illustration of future scenarios for coastal water quality in China. GO is Global Orchestration of the Millennium Ecosystem Assessment and assumes environmental actions that are either absent or ineffective in reducing water pollution. CP is based on GO, but incorporates the “Zero Growth in Synthetic Fertilizers after 2020” policy. OPT-1 and OP-2 are optimistic scenarios that assume high nutrient use efficiencies in agriculture (OPT-1, OPT-2) and sewage (OPT-2).

My PhD thesis reveals novel insights for effective environmental policies in China. It shows the importance of manure point sources in water pollution by nutrients. Clearly, managing this source will likely reduce coastal eutrophication in the future. Furthermore, the implementation of advanced technologies is essential when dealing with urban pollution. My PhD thesis may also be useful for other world regions with similar environmental problems as in China. The new, sub-basin scale MARINA model is rather transparent and thus can be applied to other large, data-poor basins that may benefit from the allocation of effective management options. With this I hope to contribute to future availability of sufficiently clean water for next generations, not only in China, but also in other world regions.

The neurotoxin BMAA in aquatic systems : analysis, occurrence and effects
Faassen, E.J. - \ 2016
University. Promotor(en): Marten Scheffer, co-promotor(en): Miguel Lurling. - Wageningen : Wageningen University - ISBN 9789462577855 - 194 p.
cum laude - neurotoxins - aquatic environment - urban areas - effects - environmental impact - daphnia magna - elisa - water quality - analytical methods - aquatic ecology - neurotoxinen - aquatisch milieu - stedelijke gebieden - effecten - milieueffect - waterkwaliteit - analytische methoden - aquatische ecologie

Eutrophication is a major water quality issue and in many aquatic systems, it leads to the proliferation of toxic phytoplankton species. The neurotoxin β-N-methylamino-L-alanine (BMAA) is one of the compounds that can be present in phytoplankton. BMAA has been suggested to play a role in the neurodegenerative diseases Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis, although this hypothesis still needs to be confirmed. It is expected that the main human exposure pathways to BMAA are through direct contact with BMAA containing phytoplankton and through ingestion of BMAA contaminated food, such as fish and shellfish. However, reports on the occurrence of BMAA in aquatic systems have been conflicting and the cause of these reported differences was heavily debated. The use of different analytical methods seems to play a crucial role in the observed discrepancies, but initially, there was little consensus on which method produced most reliable results. The objectives of the work presented in this thesis therefore were to find out what has caused the differences in published results on BMAA concentrations, and to identify and produce reliable data on the presence of BMAA in aquatic systems. In addition, I aimed to determine the effect of BMAA exposure on a key species in many freshwater ecosystems, the grazer Daphnia magna.

The performances of different analytical techniques were compared, and LC-MS/MS analysis, either preceded by derivatisation or not, was found to produce most reliable results. LC-FLD and ELISA should not be used for BMAA analysis, as both methods risk misidentifying BMAA or overestimating its concentrations due to their low selectivity. When reviewing literature on the presence of BMAA in aquatic systems, it was found that the observed discrepancies in results could be explained by the use of unselective analytical methods in some studies, and by severe reporting deficiencies in others. When only studies that used appropriate analytical techniques and that correctly reported their work were taken into account, it was shown that BMAA could be present in phytoplankton and higher aquatic organisms, in concentrations of µg/g dry weight or lower. These results are in agreement with our findings of BMAA in cyanobacterial scums from Dutch urban waters. In a 2008 screening, BMAA was found to be present in 9 out of 21 analysed cyanobacterial scums, at concentrations ranging from 4 to 42 µg/g dry weight. When this screening was repeated 8 years later with 52 similar samples, BMAA was detected below the quantification limit in one sample and quantified in another sample at 0.6 µg/g dry weight.

In order to perform the work presented in this thesis, sensitive and selective analytical methods, mostly based on LC-MS/MS analysis without derivatisation, were developed. This resulted in a standard operating procedure for the underivatised LC-MS/MS analysis of BMAA in cyanobacteria. Also, a CYANOCOST initiated workshop was given, in which a group of scientists from 17 independent laboratories evaluated LC-MS/MS based methods in different matrices. A bound BMAA from found in the supernatant was the most abundant fraction in the positive samples that were tested: cycad seed, seafood and exposed D. magna. In addition, it was found that the deuterated internal standard used for quantification was not a good indicator for the release of BMAA from bound forms, resulting in unprecise quantification of total BMAA.

BMAA was found to reduce survival, somatic growth, reproduction and population growth in D. magna. Animals did not adapt to BMAA exposure: exposed animals born from exposed mothers had a lower brood viability and neonate weight than animals exposed to BMAA, but born from unexposed mothers. In addition, D. magna was shown to take up BMAA from the growth medium and to transfer it to its offspring. D. magna therefore might be an important vector for BMAA transfer along the pelagic food chain, but whether BMAA plays a role in preventing zooplankton from controlling cyanobacterial blooms needs further investigation.

Although BMAA research has much progressed between the start of this thesis’ work and its completion, some important questions still require an answer. Most urgently, it should be determined whether BMAA is indeed involved in the neurological diseases mentioned above, and if so, which doses trigger the onset of these diseases. Human exposure pathways should then be more systematically quantified, and it might be prudent to investigate if the occurrence of BMAA is restricted to aquatic systems, or whether sources from terrestrial systems contribute to BMAA exposure as well.

Feed sources for livestock : recycling towards a green planet
Zanten, H.H.E. van - \ 2016
University. Promotor(en): Imke de Boer, co-promotor(en): Paul Bikker; Bastiaan Meerburg. - Wageningen : Wageningen University - ISBN 9789462578050 - 251 p.
cum laude - livestock - livestock feeding - feeds - resources - food wastes - leftovers - recycling - greenhouse gases - environmental impact - innovations - sustainable animal husbandry - animal production - vee - veevoeding - voer - hulpbronnen - voedselafval - etensresten - broeikasgassen - milieueffect - innovaties - duurzame veehouderij - dierlijke productie

Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Current levels of production of especially animal-source food (ASF), pose severe pressure on the environment via their emissions to air, water, and soil; and their use of scarce resources, such as land, water, and fossil energy. The livestock sector, for example, is responsible for about 15% of the global anthropogenic emissions of greenhouse gases and uses about 70% of global agricultural land.

Many proposed mitigation strategies to feed the world sustainably, therefore, focus primarily on reducing the environmental impact of the livestock sector, so-called production-side strategies. Other strategies focus on changing consumption patterns by reducing consumption of ASF, or on shifting from ASF with a higher environmental impact (e.g. beef) to ASF with a lower environmental impact (e.g. pork or chicken), so called consumption-side strategies.

Most of the environmental impact of production of ASF is related to production of feed. One production-side strategy to reduce the environmental impact is the use of products that humans cannot or do not want to eat, such as co-products, food-waste, and biomass from marginal lands for livestock feed (referred to as ‘leftover streams’ in this thesis). This strategy is effective, because feeding leftover streams to livestock transforms an inedible food stream into high-quality food products, such as meat, milk, and eggs.

Two production-side strategies that use leftover streams as livestock feed were explored in this thesis: replacing soybean meal (SBM) in diets of growing pigs with either rapeseed meal (RSM) or with waste-fed larvae meal. Replacing SBM with RSM in growing-pig diets was assessed because RSM became increasingly available following an increase in bio-energy production in the EU. In this strategy, therefore, the RSM content in pig diets increased at the expense of SBM. SBM is an ingredient associated with a high environmental impact. It was expected, therefore, that replacing SBM with RSM in pig diets would lead to a decrease in the environmental impact of pork production. Replacing SBM with waste-fed larvae meal was assessed because recent developments show the environmental benefits of rearing insects as livestock feed. Insects have a low feed conversion ratio (kg feed/kg product) and can be consumed completely, without residual materials, such as bones or feathers. The nutritional value of insects is high, especially as a protein source for livestock. Insect-based feed products, therefore, can replace conventional feed ingredients, such as SBM. Altogether this strategy suggests that waste-fed larvae meal might become an important alternative feed source in the future.

To gain insight into the status quo of the environmental impact of both mitigation strategies, replacing SBM with RSM or with waste-fed insects, we first used the attributional life cycle assessment (ALCA) method. Based on the ALCA method, results showed that each mitigation strategy was promising. Replacing SBM with RSM in growing pig diets hardly changed either global warming potential (GWP) or energy use (EU), but decreased land use (LU) up to 16% per kg body weight gain. As expected, feed production had the largest environmental impact, responsible for about 50% of the GWP, 60% of the EU, and 77% of the total LU. Feed production in combination with feed intake, were the most sensitive parameters; a small change in both these two parameters changed the results. Replacing SBM with waste-fed larvae meal in growing-pig diets showed that EU hardly changed, but GWP (29%) and LU (54%) decreased per kg body weight gain. Based on ALCA results, each mitigation strategy, therefore, seems to offer potential to reduce the environmental impact of pork production. An ALCA, however, has two disadvantages: it does not account for product-packages and it does not consider feed-food competition.

The first disadvantage of ALCA was that the complexity of dealing with product-packages is not fully considered. ‘Product-package’ refers to a multiple-output situation. During the processing of sugar beet, for example, beet-pulp and molasses are produced in addition to sugar. Sugar, beet-pulp, and molasses together form a ‘package of products’ because they cannot be produced independently from each other. An ALCA does not account for the fact that the production volume of the co-product(s) depends on the demand for the determining product (e.g. sugar), which results in the limited availability of co-products. Increasing the use of co-products in animal feed, consequently, results in reducing use of a co-product in another sector, requiring them to be replaced with a different product. The environmental impact of increasing the use of a co-product or food-waste, therefore, depends on the net environmental impact. The net environmental impact refers to the environmental benefits of using the product in its new application minus the environmental cost of replacing the product in its old application.

A consequential theoretical framework was developed to account for product-packages. The results, based on the consequential framework, contradicted standard ALCA results. The consequential LCA (CLCA) method we used for replacing SBM with RSM showed an increased GWP (up to 15%), EU (up to 12%), and LU (up to 10%) per kg body weight gain. Moreover, this CLCA method showed that replacing SBM with waste-fed larvae meal increased GWP (60%) and EU (90%), but decreased LU (73%) per kg body weight gain.

Accounting for product-packages increased the net environmental impact of each strategy, replacing SBM with RSM or with waste-fed larvae meal. The difference in results between ALCA and CLCA was especially large in the strategy with waste-fed larvae meal. The difference was caused mainly by the use of food-waste. Food-waste fed to larvae was used initially to produce bio-energy via anaerobic digestion. In CLCA, the environmental impact related to replacing the bio-energy function of food-waste with fossil-energy was included. The net environmental impact became negative, because environmental benefits of replacing SBM with waste-fed larvae meal were less than environmental costs related to the marginal energy source, i.e. fossil energy, replacing the bio-energy. Results of the indirect environmental impact, however, are situation specific: if the marginal energy source were wind or solar energy, the net environmental impact of using waste-fed larvae meal might be positive. Waste-fed larvae meal, therefore, appears to be an interesting mitigation strategy only when energy from wind and solar energy are used more dominantly than energy from fossil sources.

If results were based solely on ALCA, then these potentially negative impacts would have been overlooked. Consideration of the environmental consequences of product-packaging, therefore, is essential to determine total environmental costs. If policy makers or the feed industry want to assess the net environmental impact of a potential mitigation strategy, then we recommend to perform a CLCA instead of an ALCA. The framework developed in this thesis can be used to perform such an assessment.

The second disadvantage of an LCA was that it does not take into account feed-food competition, e.g. competition for land between humans and animals. Most LCA studies focus on the total amount of land required to produce one kg ASF. LCA studies do not account for competition for land between humans and animals, or so-called feed-food competition. In other words, they do not include, differences in the consumption of human-edible products by various livestock species or differences in the suitability of land used for feed production as land to cultivate food-crops directly. Given the global constraints on land, it is more efficient to grow food directly for human consumption rather than for livestock. To address the contribution of livestock to a future sustainable food supply, a measure for land use efficiency was developed, called the land use ratio (LUR). The LUR accounts for plant productivity, efficiency of converting human-inedible feed into ASF, and suitability of land for crop cultivation. The LUR also has a life-cycle perspective.

Results of the LUR illustrated that dairy cows on sandy soil, laying hens, and pig production systems in the Netherlands have a LUR >1.0. In terms of protein produced per m2, therefore, it is more efficient to use these soils for livestock production to produce crops for direct human consumption than to produce feed for livestock. Only dairy cows on peat soil produce human digestible protein (HDP) more efficiently than crops do, because peat is not suitable for crop production. The LUR allows identification of livestock production systems that are able to produce HDP more efficiently than crops do. Livestock systems with a LUR<1.0, such as dairy on peat, have an important role to play in future sustainable nutrition supply.

Results of the LUR showed that livestock production systems using mainly co-products, food-waste, and biomass from marginal land, can produce human digestible protein more efficiently than crop production systems do. The availability of those leftover streams, however, is limited and, therefore, the amount of ASF produced based only on leftover streams is also limited. Because LUR is a ratio, LUR results do not give an indication of how much ASF can be produced based on livestock systems that feed mainly on leftover streams.

The third, and last, mitigation strategy, therefore, focused on the amount of ASF that can be consumed by humans, when livestock are fed only on leftover steams, also referred to as “default livestock”. The calculation of the amount of ASF was based on the assumption that a vegan diet was consumed in principle. The resulting co-products and food-waste were fed to pigs and, biomass from grazing land was fed to ruminants. Results showed that in total 21 g animal source protein per person per day could be produced by feeding livestock entirely on leftovers.

Considering feed-food crops and feeding food-waste made an important contribution to the 21 g of protein that could be produced from default livestock. Considering feed-food crops implies that choices have to be made between different crops, based on their contribution to feed and food production. Oil production from soy cultivation, for example, resulted in the co-product SBM. Results showed that considering feed-food crops can affect the final protein production from pork. The practice of feeding food-waste to livestock is currently prohibited due to problems of food safety but the practice shows potential in extensively reducing the environmental impact of livestock production. Considering feed-food crops and feeding food-waste are examples of mitigation strategies that currently can be implemented to reduce further the environmental impact of the livestock sector.

On average, it is recommended to consume about 57 g of protein from ASF or plant-origin per person per day. Only ASF from default livestock does not fulfil the current global protein consumption of 32 g per person per day, but about one third of the protein each person needs can be produced without any competition for land between feed and food production. To feed the world more sustainably, by requiring livestock production systems with a LUR <1.0, however, a paradigm shift is needed. Global average consumption of ASF should decrease to about 21 g of protein per person per day. Innovations are needed, moreover, to overcome problems of food safety and technical concerns related to collecting the leftover streams. This applies, in particular to food-waste, which is currently unused in livestock production but which presents a valuable strategy in mitigating environmental impacts caused by livestock production. Livestock systems should change their focus, furthermore, from increasing productivity per animal towards increasing protein production for humans per ha. By using leftover streams optimally, the livestock sector is able to produce a crucial amount of protein, while still avoiding competition for land between feed and food crops. Livestock, therefore, can make an important contribution to the future nutrition supply.

To tweet or not to tweet : the role of personality in the social networks of great tits : the role of personality in the social networks of great tits
Snijders, L. - \ 2016
University. Promotor(en): Marc Naguib, co-promotor(en): Kees van Oers. - Wageningen : Wageningen University - ISBN 9789462576940 - 237 p.
cum laude - parus major - personality - communication between animals - social structure - vocalization - bird song - social behaviour - animal behaviour - behavioural biology - persoonlijkheid - communicatie tussen dieren - sociale structuur - vocalisatie - vogelzang - sociaal gedrag - diergedrag - gedragsbiologie

To tweet or not to tweet: The role of personality in the social networks of great tits
By: Lysanne Snijders

Project video: https://www.youtube.com/watch?v=zy0HysxhQz0

When mentioning social networks it is easy to think of online networks for people, such as Facebook and Twitter. But many animals also have social networks. In proximity networks they encounter each other physically and in communication networks they connect to each other by using signals. Their position in such social networks is important. It can influence the likelihood of finding new food, acquiring novel foraging techniques, rising in social status and acquiring a mate. However, having many contacts can also be risky as it increases the likelihood of encountering infectious diseases, social stress or ending up in a fight.
As social network position can be so significant, it is essential that we know what determines it. A likely key factor is personality. Individuals consistently differ in how risk-prone (pro-active) and risk-averse (re-active) they tend to behave. As making face-to-face contact is not without risk, bolder individuals might have more social contacts.

An ideal model to study this hypothesis is the great tit. A common garden bird. There are well established methods to quantify personality differences in great tits and with the newest tracking technologies we can now also monitor their face-tot-face contacts. What makes the great tit even more interesting is that they like to breed in nest boxes and so we can also study potential fitness effects of specific network positions. Additionally, great tits are songbirds, which makes them also ideal to answer a second question: Do individuals that are shy to approach others, use communication instead? Since communication is often a less risky connection strategy than face-to-face contact.

In this PhD thesis I reveal how and when personality explains why some birds are better connected than others. In wild territorial populations pro-active males were better connected to other males and were most likely to approach a rival. In contrast, when removing the risk of fights during male-to-male spatial associations, via a video-playback experiment in captivity, the re-active males appeared to be most social. When confronted with the life-size video image of a novel conspecific, they spent the most time associating with it. When lowering the risks associated with spatial associations the social preferences of re-active individuals might thus increase. No relationship was found between social network position in the wild and reproductive success, an important fitness component.
Wild male great tits that were less likely to approach a rival, sang more actively at dawn. Dawn song is the peak time for male great tit singing activity and operates as a large communication network. Since a prime function of singing at dawn is territory advertisement, these birds might thus try to prevent rival territory intrusions by singing more fiercely at dawn. No direct links were found between personality and an individual’s place in the communication network, however pro-active birds vocalized most actively during territory intrusions and increased their singing activity significantly during the fertile period of their mate.
Communication networks and proximity networks can influence each other via song, by attracting or repulsing conspecifics to come close. For example, the vocal response of an intruded male to its rival significantly influenced whether female neighbours would come close to the intrusion site and if male neighbours would stay away.

What determines the place in a social network? By knowing this we learn more about how groups function and how different social strategies in the same population can co-exist.

Multi-population genomic prediction
Wientjes, Y.C.J. - \ 2016
University. Promotor(en): Roel Veerkamp; Mario Calus. - Wageningen : Wageningen University - ISBN 9789462576193 - 267 p.
cum laude - dairy cattle - genomics - prediction - quantitative trait loci - genetic improvement - breeding value - selective breeding - animal breeding - animal genetics - melkvee - genomica - voorspelling - loci voor kwantitatief kenmerk - genetische verbetering - fokwaarde - selectief fokken - dierveredeling - diergenetica
Cum laude graduation
Ecosystem effects of bottom trawl fishing
Denderen, P.D. van - \ 2015
University. Promotor(en): Adriaan Rijnsdorp, co-promotor(en): Tobias van Kooten. - Wageningen : Wageningen University - ISBN 9789462573468 - 182
vis vangen - zeevisserij - boomkorvisserij - vismethoden - ecosystemen - milieueffect - visserijbeheer - benthos - soortenrijkdom - mariene ecologie - fishing - marine fisheries - beam trawling - fishing methods - ecosystems - environmental impact - fishery management - species richness - marine ecology - cum laude
cum laude graduation
The conservation and use of crop genetic resources for food security
Khoury, C.K. - \ 2015
University. Promotor(en): Paul Struik, co-promotor(en): A. Jarvis. - Wageningen : Wageningen University - ISBN 9789462574427 - 302
genetische bronnen van plantensoorten - genetische diversiteit - germplasm - landbouwontwikkeling - klimaatadaptatie - wilde verwanten - ex-situ conservering - voedselzekerheid - plant genetic resources - genetic diversity - agricultural development - climate adaptation - wild relatives - ex situ conservation - food security - cum laude
Cum laude graduation
Among the factors hindering the conservation of crop genetic resources is a lack of essential information regarding this diversity. Questions include: (a) what is the status of diversity in our food systems, and where are the greatest vulnerabilities?, (b) where can genetic diversity be found that can be useful in increasing productivity and mitigating these vulnerabilities?, (c) is this genetic diversity available in the present and in the long term?, and (d) what steps are needed to improve the ability for researchers to access genetic resources critical for present and future crop improvement? This thesis aims to contribute to the knowledge required to answer these questions through an exploration of the need for, potential of, challenges and constraints regarding, and necessary steps to enhance the conservation and use of crop genetic diversity.
Evolution, role and mechanism of prokaryotic Argonaute proteins
Swarts, D.C. - \ 2015
University. Promotor(en): John van der Oost, co-promotor(en): Stan Brouns. - Wageningen : Wageningen University - ISBN 9789462572959 - 228
eiwitten - eiwittechnologie - rna-interferentie - genexpressie - nucleasen - thermus thermophilus - pyrococcus furiosus - proteins - protein engineering - rna interference - gene expression - nucleases - cum laude
cum laude graduation
The hybrid nature of pig genomes : unraveling the mosaic haplotype structure in wild and commercial Sus scrofa populations
Bosse, M. - \ 2015
University. Promotor(en): Martien Groenen, co-promotor(en): Hendrik-Jan Megens; Ole Madsen. - Wageningen : Wageningen University - ISBN 9789462573000 - 253
dieren - varkens - dierveredeling - genomen - hybridisatie - sus scrofa - haplotypen - genomica - populaties - genetische variatie - animals - pigs - animal breeding - genomes - hybridization - haplotypes - genomics - populations - genetic variation - cum laude
cum laude graduation
Tales on insect-flowering plant interactions : the ecological significance of plant responses to herbivores and pollinators
Lucas Gomes Marques Barbosa, D. - \ 2015
University. Promotor(en): Marcel Dicke, co-promotor(en): Joop van Loon. - Wageningen : Wageningen University - ISBN 9789462572119 - 207
bloeiende planten - insecten - insect-plant relaties - plant-herbivoor relaties - herbivoren - bestuivers (dieren) - trofische graden - parasitoïden - herbivoor-geinduceerde plantengeuren - flowering plants - insects - insect plant relations - plant-herbivore interactions - herbivores - pollinators - trophic levels - parasitoids - herbivore induced plant volatiles - cum laude
cum laude graduation
Animal deliberation : the co-evolution of technology and ethics on the farm
Driessen, C.P.G. - \ 2014
University. Promotor(en): Michiel Korthals, co-promotor(en): Volkert Beekman. - Wageningen : Wageningen University - 356
dierethiek - ethiek - veehouderij - varkenshouderij - technologie - boeren - varkens - dierlijke productie - animal ethics - ethics - livestock farming - pig farming - technology - farmers - pigs - animal production - cum laude
cum laude graduation
Biogenesis and signalling requirements of plant receptor-like proteins mediating resistance to fungal pathogens
Liebrand, T.W.H. - \ 2014
University. Promotor(en): Pierre de Wit, co-promotor(en): Matthieu Joosten. - Wageningen : Wageningen University - ISBN 9789461738622 - 192
solanum lycopersicum - plantenziekteverwekkende schimmels - passalora fulva - verticillium dahliae - ziekteresistentie - verdedigingsmechanismen - receptoren - pathogenesis-gerelateerde eiwitten - genetische analyse - genexpressie - plant pathogenic fungi - disease resistance - defence mechanisms - receptors - pathogenesis-related proteins - genetic analysis - gene expression - cum laude
cum laude graduation
Adaptive & heritable immunity in bacteria : on the regulation and mechanism of CRISPR defense
Westra, E.R. - \ 2013
University. Promotor(en): John van der Oost; Willem de Vos, co-promotor(en): Stan Brouns. - S.l. : s.n. - ISBN 9789461735003 - 254
bacteriën - immuniteit - immuunsysteem - verdedigingsmechanismen - rna - prokaryoten - bacteria - immunity - immune system - defence mechanisms - prokaryotes - cum laude
cum laude graduation (with distinction)
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