Curriculum Vitae
Education
- 1991 – 1997 BSc, MSc Biology at the University of Groningen, cum laude
- 1997 – 2003 PhD at the Nature Conservation and Plant Ecology Group, Wageningen University
Employment
- 2002 – 2003 Lecturer at the Nature Conservation and Plant Ecology Group, Wageningen University (NL)
- 2003 – 2004 Postdoc at the School of Biological Sciences, University of Nebraska (USA)
- 2004 – 2005 Postdoc at the Department of Biological Sciences, University of Alberta (Canada)
- Spring 2005 Lecturer at the Department of Biological Sciences, University of Alberta (Canada)
- 2005 - 2009 Postdoc at the Department of Plant-Animal Interactions, Netherlands Institute of Ecology (NL)
- 2009 - present Tenure track at the Department of Aquatic Ecology, Netherlands Institute of Ecology (NL)
Grants & awards
- 2003 Best paper award Journal of Vegetation Science (see Bastow et al. 2004, JVS 15, pp 1–2)
- 2004 – 2005 Talent–stipendium from Netherlands Organisation of Scientific Research (NWO)
- 2007 - 2010 VENI-grant Innovational Research Scheme NWO, project: "Causes and consequences of plant palatability along a gradient of resource availability"
- 2009 Grant Agentschap NL, Dutch Ministry of Economic Affairs, Agriculture & Innovation, project: "Flexibel peil: van denken naar doen", a project on effects of water level fluctuations on macrophytes
- 2010 Scientific prize for conservation of biodiversity (Ministry of Economic Affairs, Agriculture & Innovation)
- 2011 Grant program "Biodiversity works" NWO, project: "Ecosystem functions of invasive aquatic plants"
Expertise
Plant-animal interactions
Would the world look differently if herbivores would be absent? I try to understand how herbivores affect their environment from individual plant species to the landscape level. Herbivore grazing does not cause a uniform effect; herbivore impact depends on plant resource availability in the environment. I study the mechanisms which cause herbivore effects to be environment dependent both in terrestrial and aquatic systems.
Plant diversity
Vertebrate herbivores can have a strong impact on plant diversity. These effects can be positive or negative. I study through which mechanisms herbivores can affect diversity and try to find general rules that can help to predict in which situations herbivore effects are positive or negative. One of the key factors may be the palatability of the dominant plant species to herbivores; palatability in turn may vary with nutrient availability.
Nutrient cycling
Herbivores can increase nitrogen mineralization rates through consumption of plants and excretion of nutrients as faeces. On the contrary, they can decrease mineralization if they promote the abundance of plant species with low quality litter by selectively consuming and thus removing, the high quality species. The net impact of herbivores on nitrogen cycling is therefore difficult to predict. I study the impact of herbivores on nutrient availability in grasslands and freshwater systems.
Foraging behaviour and food selection
In contrast to terrestrial systems, aquatic herbivores are mostly omnivorous, e.g. they include both plants and animals in their diet. I'm testing the level of herbivory and plant selection for different aquatic facultative herbivores, fish, waterfowl and invasive crayfish. Plant and animal traits that may affect palatability include the level of secondary metabolites, toughness and plant stoichiometry.
Nature conservation
Vertebrate herbivores can play an important role in nature conservation, through their positive or negative effects on plants and dependent fauna. Domestic herbivores for example are used as a management tool to preserve grassland biodiversity. Expanding Greylag goose populations on the other hand are blamed for preventing establishment of reed vegetation in shallow water. I try to establish under which environmental conditions herbivore impact is positive or negative, which can help nature managers in their decisions concerning herbivore population management. Furthermore, management of abiotic factors offers possibilities to restore ecosystems and biodiversity. In freshwater nutrient reduction and water level fluctuation may be promising tools to improve water quality and biodiversity.
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If you are a student with an interest in waterplants or plant-animal interactions feel free to contact me. You can find a list with possible research topics here
Projects
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Herbivores can play an important role in the structuring of plant communities, which has been shown to vary with environmental gradients of resource availability. This has been hypothesized to be due to variation in plant palatability over a resource gradient, for instance through changes in plant stoichiometry and anti-herbivore defenses. I test whether plant palatability and stoichiometry changes with resource availability (nutrients and light) using freshwater macrophytes as a model system. I use exclosure studies to test whether differential palatability is a cause of shifts in plant community composition over a productivity gradient.
 
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Grazing impact on aquatic plants varies from zero to almost 100% plant removal and it's currently unknown what causes this variation. Herbivore density is a logical candidate to explain this variation between studies, but has been shown to be relatively unimportant. Alternatively, nutrient availability can affect the impact of herbivore grazing both through altered plant palatability as well as plant resistance to grazing. I test this hypothesis by excluding vertebrate grazers and compare their effects in an oligotrophic, mesotrophic and eutrophic lake. Additionally, I test the impact of grazing on macrophytes, nutrient availability and phytoplankton blooms by allowing captive mallards to graze on oligotrophic and eutrophic experimental ponds.
 
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Water level fluctuations affect the growth and establishment of helophytes and macrophytes. Especially helophytes profit from a temporary drawdown of the water. A stagnant water level, as maintained in many western european water bodies, may be a cause of limited expansion of helophytes into the open water or even decline which is observed especially in "water reed" which grows with its feet in the water. Alternatively grazers, such as Greylag geese may be a cause of reed decline and limited terrestrialisation (see picture). We are testing the importance of water level fluctuations and grazing as limiting factors for establishment and expansion of helophytes and sumerged macrophytes.
Grazing by Greylags alters the architecture of the reed stems and provides a direct link between the sediment and air. The effects of grazing on methane emission from reed stems is the topic of the most recent investigations.
 
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Almost all freshwater herbivores are in fact omnivorous. This makes it difficult to predict herbivore effects on plants. In this project we study the choice of freshwater fish between macrophyte species and macrofauna and measure the impact of a herbivorous (Grasscarp) and omnivorous fish (Rudd) on macrophyte vegetation and water quality in experimental ponds together with an analysis of their diet in the ponds.
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Selected Publications
A full list of publications can be found here
Dorenbosch, M. & E.S. Bakker (2011) Herbivory in omnivorous fishes: effect of plant secondary metabolites and prey stoichiometry. Freshwater Biology 56: 1783-1797
Dingemans, B.J.J., P.E. Bodelier & E.S. Bakker (2011) Aquatic herbivores facilitate the emission of methane from wetlands. Ecology 92: 1166-1173
Bakker, E.S., E. van Donk, S.A.J. Declerck, N.R. Helmsing, B. Hidding & B. Nolet (2010) Effect of macrophyte community composition and nutrient enrichment on plant biomass and algal blooms. Basic and Applied Ecology 11: 432-439
Bakker E.S., J.M.H. Knops, D.G. Milchunas, M.E. Ritchie & H. Olff (2009) Cross-site comparison of herbivore impact on nitrogen availability in grasslands: the role of plant nitrogen concentration. Oikos 118:1613-1622
Bakker E.S., H. Olff & J.M. Gleichman (2009) Contrasting effects of large herbivore grazing on smaller herbivores. Basic and Applied Ecology 10: 141-150
Bakker E.S., M.E. Ritchie, H. Olff, D.G. Milchunas & J.M.H. Knops (2006) Herbivore impact on grassland plant diversity depends on habitat productivity and herbivore size. Ecology Letters 9: 780-788
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