Projecten van de werkgroep Aquatische Ecologie

(Alleen Engelse titels)

Explaining the structure and dynamics of communities by means of individual-based simulation models (OSIRIS)
Research period 1993-2010
Research team W.M. Mooij
In cooperation with Dr. D.L. DeAngelis (USGS)
Contact person W.M. Mooij
Funding KNAW

Objectives: To integrate individual-based modelling of animal communities with traditional modelling approaches based on differential equations and to apply this integrated framework to explaining the structure and functioning of populations and communities with special emphasis on freshwater ecosystems.
Interactions among three closely related Daphnia 'species' in contrasting environments - a microcosm study (COSM)
Research period 1995 – 2008
Research team J. Vijverberg
In cooperation with Dr. Leonard V. Polishchuk (Moscow University, Russia)
Contact person J. Vijverberg
Funding: KNAW, Schure-Beijerinck-Popping Fund and NWO
Objectives: The following questions will be addressed: (1) What are the effects of three types of predation on the species composition of the zooplankton community; and, 2) What is the effect of food competition on the species composition of the zooplankton community. The results obtained may help to explain the seasonal succession of these species in nature.
Viability of food specialist in a fluctuating heterogeneous environment: the Everglade Snail kite (EVERKITE)
Research period 1996-2010
Research team W.M. Mooij
In cooperation with Dr. D. DeAngelis (USGS), Dr. M. Gaines, University of Miami, Dr. I. van der Stap (University of Miami), Dr. J. Martin (University of Florida)
Contact person W.M. Mooij
Funding US Army Corps of Engineers through the University of Miami
Objectives: To develop and apply a model for the performance of the snail kite population in southern and central Florida under various hydrological scenarios. To this purpose an individual-based spatially-explicit simulation model, which keeps track of the fate of individual kites in each of the fifteen major wetlands of southern and central Florida, is constructed and analyzed.
The role of fungal parasites in phytoplankton growth and succession (PARASITE/DIATOM)
Research period 2001-2011
Research team A. Gsell), B. Ibelings, M. Rijkeboer, M. Brehm and E. van Donk (promotor)
Contact persons E. van Donk, B. Ibelings
Funding NWO-ALW./ EAWAG
Objectives: The objective of this study is to demonstrate parasite driven clonal selection (microevolution) in natural populations of the host. Selective changes in natural systems have been difficult to detect, results have been hard to interpret. Our study has been designed, through a combination of field and tightly linked microcosm studies to either demonstrate parasite mediated selection or – should selection be obscured - to understand why microevolution of the host was not detected. To achieve this aim we plan to investigate a number of potential constraints on selection that may operate under natural conditions.
The following main hypothesis will be tested by the study: Epidemic development of the virulent chytrid parasite Zygorhizidium will drive microevolution of its host, the diatom Asterionella, such that: a) The frequency distribution of host clones before and after the epidemic is significantly different; b) The proportion of – relatively – resistant host clones increases during the epidemic, i.e. the epidemic selects for enhanced resistance at the population level; c) Asterionella strains surviving after the epidemic have - on average - a higher fitness - in the presence of the parasite - than those from before the epidemic; this fitness advantage is reversed in the absence of a parasite.
Inducible defences: from individual plasticity to food web dynamics and persistence (DEFENCE)
Research period 2002-2008
Research team I.van der Stap (PhD student), W.M. Mooij, M. Vos, E. van Donk (promotor), F. Wäckers, L. Vet
In cooperation with Prof.dr.R.Tollrian (Univ of Munich), Prof.dr.M. Dicke (WUR), Dr.B. Kooi (VU), Prof.dr.M. Ritchie (Utah St Univ), Dr. D. DeAngelis (USGS)
Contact person W.M. Mooij
Funding NWO-ALW
Objectives: Consumer densities can fluctuate, and bacteria, plants and animals can respond to the presence and density of their consumers with a variety of inducible defences. Theoretically, inducible defences have the potential to stabilise or destabilise interactions, thus affecting both population-level persistence and the integrity of the food web. Furthermore, inducible defences can temporarily decouple or modulate the interaction between trophic levels, thus affecting the balance of bottom-up versus top-down control or flows of energy. Theoretical models predict that inducible defences and diversity have a synergistic effect on food web persistence. These predictions will be experimentally tested in assembled freshwater communities with a focus on the effects of inducible defences on the dynamics and persistence of simplified tri-trophic food webs.
Chasing the Red Queen (QUEEN)
Research period 2002-2009
Research team B. Ibelings, M. Rijkeboer, M. Brehm and E. van Donk
Contact person B. Ibelings
Funding KNAW / EAWAG (CH).
Objectives: The Red Queen is an important evolutionary hypothesis that has been put forward to explain diverse phenomena like the evolution of sex and maintenance of genetic polymorphism. Despite its importance good experimental evidence for the Red Queen is lacking. We set out to find support for the central prediction of the Red Queen that of accelerated evolution under biological interaction. Two types of biological interactions are being studied: parasitism (between algae and fungi) and resource competition between the cyanobacterium Synechocystis and the green alga Chlamydomonas. Gene expression studies will be performed over evolutionary time scales. These should inform us which are candidate genes for the co-evolutionary adaptation under resource competition.
From the overall aim outlined above we can distil 3 key objectives for the experiment. These are: a) to test the hypothesis that the co-evolutionary arms race between interacting species accelerates evolution in comparison to the situation where biological interactions are absent (or minimised); b) to identify those genes that are involved in co-evolutionary adaptation and are responsible for the gain in fitness; c) to test the hypothesis that the fixation of a limited number of beneficial mutations steers most of the adaptation in overall gene expression (as implicated in experiments with yeast by Ferea et al, 1999).
Connectivity, dispersal and priority effects as drivers of biodiversity and ecosystem function in pond and pool communities (BIOPOOL)
Research period 2006-2010
Research team D. Gerla (PhD student), W.M. Mooij, E. van Donk (promotor)
In cooperation with Prof. Dr. L. de Meester (University of Leuven), Dr. M. Vos (NIOO), Dr.B. Kooi (VU)
Contact person W.M. Mooij
Funding ESF/NWO-ALW
Objectives: In this project, we will use pond communities throughout Europe as model systems for testing
central hypotheses on the impact of dispersal, colonization and priority effects on community
build-up and their consequences for ecosystem functioning. Our main objectives are to (1)
characterise the relative importance of dispersal (determined by regional factors), historical
effects (e.g. priority effects, partly mediated by propagule banks) and assemblage processes
(driven by local factors) on biodiversity, and to (2) quantify the effect of diversity and genetic
variation on ecosystem functioning, particularly exploitation efficiency and resistance to
biological invasions.
Multiple stressors - The combined effect of pesticides, cyanotoxins and infochemicals on zooplankton (MULTISTRESS)
Research period 2007-2008
Research team S. Cerbin (Postdoc), E. van Donk and J. Vijverberg
In cooperation with Prof. W. Admiraal and Michiel Kraak (Department of Aquatic Ecology and Ecotoxicology, UvA); Petra Visser (Department of Aquatic Microbiology, UvA), Pim de Voogt (Earth Surface Processes and Materials, UvA)
Contact person E. van Donk
Funding EU, Marie Curie Intra-European Fellowship
Objectives: The goal of this project is to describe the combined influences of multiple stress factors on zooplankton species dynamics and community structure. Zooplankton plays important role in aquatic food webs and it is crucial to know how anthropogenic chemicals and cyanotoxins affect population dynamics and community structure. This knowledge is of high importance from economical (e.g. losses in aquaculture) and environmental (e.g. ecosystem stability) point of view.
Genomic approach to study induced defence in cyanobacteria (CYANOGEN)
Research period 2007-2009
Research team S. Becker (Postdoc), E. van Donk
In cooperation with Dr. H. Matthijs (UvA, Amsterdam),
Dr. N. Tandeau de Marsac (Institut Pasteur, Paris)
Contact person E. van Donk
Funding KNAW
Objectives: To study induced defence in cyanobacteria, it is necessary to elucidate biotic and abiotic factors that determine colony formation and toxin synthesis. In this project we will use the toxin-producing model cyanobacterium Microcystis aeruginosa PCC 7806 to focus on biotic factors, i.e. the presence of grazers like Daphnia and Ochromonas. We would like to know which effect such grazers have in batch cultures on the model organism, with respect to colony formation, toxin (microcystin) synthesis and transcription of relevant genes. Recently, the genome of PCC 7806 has been sequenced, and annotation is underway. Thus microarray studies of genome-wide gene transcription will become available in the near future. We are also interested in the regulation of buoyancy in PCC 7806, because this may be an important factor that determines the population dynamics of these cyanobacteria in situ.
Comparative fish community and food web research in lakes and reservoirs along a temperature gradient (FISHSTRAT)
Research period 1995 - 2008
Research team J. Vijverberg Dr. E. Dejen (ARARI)
In cooperation with: Dr.F.A. Sibbing (WUR), Dr.J. Nagelkerke (WUR)
Contact person J. Vijverberg
Outside funding additional funding from WOTRO and Schure-Beijerinck-Popping Fund.
Objectives: Field work was carried out in Ethiopia. During November 2004 until January 2005 nine different lakes in Ethiopia were sampled, including mountain lakes in the North and the Rift Valley lakes in the south of the country Food web properties will be compared among ecosystems and several major hypotheses will be tested, e.g.: (1) Because of its long-time physical isolation from other lakes and River Systems and its therefore separate evolution of the fish stocks, the L. Tana food web (Ethiopia) differs in many respects from the other studied food webs; (2). Food-chain length is determined by ecosystem size alone and not by productivity, larger ecosystems will have longer food chains; (3) Omnivory in fish communities will increase with ecosystem size, but not with productivity; (4) The benthic-littoral sub-system will become less important and the pelagic sub-system will become more important with increasing productivity, (5) Fish species richness will increase unimodallly with increasing productivity; (6) Zooplankton mean size is negatively related to temperature, (7) Zooplanktivory will increase with zooplankton mean size, (8) In tropical reservoirs small pelagic zooplanktivorous fish species from marine origin (e.g. freshwater sardine) are better adapted to lacustrine conditions than the zooplanktivores from riverine origin.
Decoupling and adaptation of trophic interactions in aquatic food webs under climate change(DECADAP)
Research period 2008-2010
Research team L.N. de Senerpont Domis (Postdoc), W.M. Mooij (project leader), E. van Donk
In cooperation with Prof.dr.M. Scheffer (WUR), Prof.dr. U. Sommer (Kiel University)
Contact person W.M. Mooij
Funding NWO
Objectives: Recent climate warming has been shown to advance the seasonal timing of life cycle events, such as budding of trees and egg laying by birds. Species-specific differences in these changes in phenology may result in a decoupling of trophic relationships in food webs and subsequent cascading effects on community structure. For the timing of life cycle events, such as emergence, moulting and sexual reproduction, each species requires specific cues, which are used as proxies for the suitability of the environment for their reproduction and growth. Climate warming may change the validity of the proxies different species use. The fundamental questions underlying our proposed research are threefold: 1) What proxies do different species use to estimate the suitability of environmental conditions for successful reproduction and growth? 2) Could projected climate warming invalidate the use of these proxies and lead to a decoupling of trophic interactions? 3) Can adaptation to projected climate warming, maintain or restore trophic interactions?

Restoration of Dutch peat lakes (DREISSENA/PEAT)
Research period 2003 - 2008
Research team Miguel Dioniso Pires, Bas Ibelings, Ellen van Donk, Gabi Mulderij (Koeman & Bijkerk)
In cooperation with Prof.dr J. Verhoeven (RUU), Dr. L. Lamers (KUN), Dr. H. Hosper (RIZA) Ronald Bijkerk Mulderij (Koeman & Bijkerk)
Contact persons Miguel Dioniso Pires, Ellen van Donk
Funding OBN-LNV
Objectives: Eutrophication of Dutch peat lakes regularly results in cyanobacteria blooms during the summer. The aim of this study is to analyse the applicability of different restoration measures on food web relationships in these peat lakes and especially the reduction of potential hazardous cyanobacteria. Cyanobacteria may be a great problem in summer for water recreation but also for the return of biological interesting species (Calla palustris, Aeshna, Lutra lutra). We are particularly interested in the effects of restoration (watertable fluctuation, biomanipulation, nutrient load reduction) on the reduction of nuisant cyanobacteria blooms. Peat lakes in the Netherlands were extensively monitored in 2003 and 2004 for phytoplankton dynamics. This was in cooperation with 2 junior researchers (University of Nijmegen and Utrecht), focussing on the biochemistry and vegetation succession of peat lakes, respectively. This monitoring of the total peatlake ecosystem in different geographical regions of the Netherlands was performed to make an overall inventarisation of the quality of peat succession. During the summer-season of 2003, we studied a food web of a peat lake where fish was removed (biomanipulation), using flowcytometry and stable isotope analysis (13C). In the coming years, grazing of large freshwater mussels (Anodonta) on cyanobacteria and effects of cyanobacteria toxins on mussels will be studied, using laboratory- and field set-ups and mesocosm experiments. This work has been published in 2007 (Aquatic Sciences). In 2007, sediment-exposure experiments were performed to see if mussels performed differently on different kind of sediments. In 2008, this work will continue together with mussel-transplant experiments.
In addition to the study of unwanted algae (cyanobacteria) emphasis will be put on the study of highly characteristic, but in many cases endangered phytoplankton species, the desmids. In collaboration with Koeman & Bijkerk the occurrence and the main steering factors therein of endangered desmids in peat lakes will be studied over the next 2 years.
Effects of increased pCO2 on freshwater food webs through physical-chemical coupling: a stoichiometric perspective (STOICHWEB)
Research period 2005 - 2008
Research team Anthony Verschoor (postdoc), Ellen van Donk
In cooperation with Dr. J.M.H. Verspagen (postdoc counterpart UvA), Prof. dr. J Huisman (UvA), Dr. P. Schippers (WUR), Prof. Dr D.O. Hessen (University of Oslo, Norway), Dr. T. Andersen (University of Oslo, Norway), Prof. Dr. J.J. Elser (Arizona State University, USA), Prof. Dr. F. Peeters (University of Konstanz, Germany), Prof. Dr. J. Urabe (Tohoku University, Japan)
Contact persons Anthony Verschoor and Ellen van Donk
Funding NWO-ALW (Water fund)
Objectives: Atmospheric carbon dioxide levels are currently increasing at unprecedented rates. Although this is known to cause the so-called ‘global warming’, the direct effects of CO2 on ecosystems are hardly understood. Freshwater lakes are particularly vulnerable to raised CO2, because this additional carbon will reach these lakes both through direct atmospheric exchange, and through runoff from increased terrestrial production in the surrounding watershed. This project aims to identify changes in food web and ecosystem functioning due to increased partial CO2 pressure (pCO2), from a stoichiometric perspective. Ecological stoichiometry studies the complex relationships between biota and biogeochemical cycles, using the balance between carbon and nutrients in organisms. This project aims at assessment of potential ecosystem effects by making accurate assessments of the interactions and feedbacks between mixing regime, pelagic carbon and nutrient cycles.
The impact of rising pCO2 on harmful cyanobacteria (CWECYANO)
Research period 2005 - 2009
Research team Dedmer van de Waal (PhD student), Ellen van Donk (promotor),
In cooperation with Prof. dr. J. Huisman (UvA) (promotor), Dr. P. Visser (UvA)
Contact persons Ellen van Donk
Funding CWE (Centre for Wetland Ecology)

Objectives: Atmospheric carbon dioxide levels have increased from a baseline level of 280 ppm about 150 years ago to more than 360 ppm at present, and are predicted to rise further to 700 ppm in the course of this century. The increased levels of dissolved inorganic carbon as a result of an increased flux from atmosphere to water affect the carbon availability and thus the carbon : nitrogen stoichiometry of lakes.
The phytoplankton of eutrophic lakes is often dominated by cyanobacteria (‘blue-green algae’). Cyanobacteria may produce a family of toxins, called microcystins, which are harmful to both humans and animals. As a result, waters dominated by such harmful cyanobacteria are often closed for recreation and cannot be used for agriculture or drinking water purposes. Microcystins are cyclic peptides based on carbon and nitrogen. We therefore hypothesize that changes in the carbon:nitrogen stoichiometry of lakes will affect microcystin production, either by physiological adaptation within cyanobacterial strains or by natural selection between different strains of cyanobacteria. Thus, the rise in atmospheric carbon dioxide might affect the toxicity of cyanobacteria.

This project aims to test this working hypothesis by a variety of different approaches:
1. Laboratory-based studies with cyanobacteria to test the hypothesis that the relative availability of carbon to nitrogen will determine microcystin production
2. Field-based studies in lakes to acquire data on C/N ratios of lakes and the microcystin contents of the prevailing cyanobacterial strains
3. Food-web studies to investigate the consequences of changes in microcystin content of cyanobacteria for zooplankton species and other aquatic organisms
4. Model development to predict the implications of changes in C/N stoichiometry on water quality and food webs in lakes dominated by harmful cyanobacteria.
Impact of climate change on the vulnerability of lakes for surface blooms of harmful cyanobacteria(CLIMCYANO)
Research period 2008 - 2012
Research team Vacancy PhD, Anthony Verschoor, Ellen van Donk (promotor),
In cooperation with Dr. K. Johnk (postdoc, Leibniz), Prof. dr. J Huisman (UvA) (promotor)
Contact persons Ellen van Donk
Funding : NWO-ALW (Water fund) and KNAW
Objectives
Cyanobacteria that form surface blooms have often gas vesicles, providing them with buoyancy. Buoyant cyanobacteria compete for light and nutrients against non-buoyant (often slowly sinking) phytoplankton species, such as green algae and diatoms. These phytoplankton groups respond differently to changes in hydrodynamic processes like lake stratification and turbulent mixing. These hydrodynamic conditions, in turn, are to a large extent driven by meteorological forces like wind stress, air temperature, and light conditions. During calm weather with only weak vertical mixing, buoyant cyanobacteria float upwards and form surface blooms, thus out-competing the other phytoplankton. During rough weather with strong wind-mixing, buoyant cyanobacteria are fully mixed throughout the water column and often lose the competition against green algae and diatoms. Furthermore, phytoplankton is affected by grazers (e.g., zooplankton, zebra mussels), and the impact of grazers may vary with climatic conditions as well. It may thus be hypothesized that gradual changes in meteorological conditions may lead to sudden shifts in phytoplankton species composition, especially in the competitive balance between buoyant cyanobacteria and other phytoplankton species.

Our main research questions are:

Under which climate scenarios and in which geographical regions can we expect increased formation (or suppression) of surface blooms of harmful cyanobacteria? In this project, we will build on recent innovations to study the link between climate, hydrodynamics, and the dominance of buoyant cyanobacteria. The PhD will be mainly stationed at NIOO and will:

1. Run laboratory experiments in advanced ‘Limnotrons’ to study the formation of surface blooms of harmful cyanobacteria, under controlled hydrodynamic conditions, and investigate the impact of grazing in this system.
2. Organize summer field campaigns in which a microstructure profiler and moored temperature loggers will be used to analyze turbulent mixing and flows in eutrophic lakes dominated by surface blooms of harmful cyanobacteria.

This multidisciplinary approach will enable improved prediction of the potential threats imposed by harmful cyanobacteria under future climate scenarios.
New integrative model of lake ecosystems functioning: stability and controllability analysis(INTEGRATE)
Research period 2005-2008
Research team W.M. Mooij, A.G. Degermendzhy, E. van Donk, R.D. Gulati
In cooperation with J.H. Janse (RIVM)
Contact persons W.M. Mooij, E. van Donk
Funding NWO-ALW
Objectives: To develop new and extend current models of lake ecosystems. The Dutch research partner will focus on re-implementing and extending the existing model for shallow lakes, PCLake. This model has been developed by J.H. Janse at RIVM. This model was primarily developed as a management tool and has its roots in the Loosdrecht restoration project. We assess that PCLAKE has the potential to become an important research tool in food web research, once a more flexible implementation would become available. Examples of research fields in which the model can be used to integrate knowledge are climate change, inducible defenses and stoichiometry. The Russian partners in the consortium will focus on developing and extending both hydro-dynamic and ecological models. Their reference system is the Siberian saline lake Shira, near Krasnoyrsk.
Ecohydromorphology in shallow lakes: quantifying effects of biological elements on abiotic processes in shallow lakes (ECOMORPH)
Research period: 2006-2010
Research team: W.E. Penning (PhD student - WL | Delft Hydraulics) M. Dionisio Pires, E. van Donk (promotor)
In cooperation with: A. Mynett (IHE) (promotor), R. Uittenbogaard (WL | Delft Hydraulics), M. de Vries (WL | Delft Hydraulics)
Contact person: W.E. Penning, E. van Donk
Funding: Delft Cluster
Shallow lakes are widespread, both in the Netherlands and in other regions. In the Netherlands, these lakes are often linked to the large drainage systems and water levels are managed in a strict way, leaving little room for a natural shore line to develop. Eutrophication and morphological pressures are therefore often occurring in a combined manner, limiting the use of simple 1 to 1 dose-response relationships for prediction purposes. The quantification of effects of measures to improve the ecological status of such a water system requires therefore an integrated assessment of all aspects, involving many disciplines ranging from hydrology to ecology. Often deterministic modelling tools are used to carry out system analyses and effects of measures,that consist of both hydrodynamic flow and water quality modules. In this project SOBEK and Delft3D are used together with the water quality process library Delwaq, in which ecological feedback mechanisms to flow and morphology are currently only available in a rather limited way.

Objectives: To develop a better description of interactions between biota and abiotic processes in shallow lakes, and to implement these in existing modelling tools, improving them for more appropriate fday to day water management. Both full lake functioning and more detailed understanding of specific ecohydromorphological processes at different scale levels are distinguished within the study. Macrophytes and filter feeders (freshwater bivalves) are the main focus per scale level. Various experimental studies and field-work are combined with deterministic modelling and specific data for model calibration and validation will be gathered.
Impact of eutrophication status and fisheries on major pathways in Lake Victoria food webs: a combined experimental and field study approach (SEDEC-1)
Research period 2008 - 2011
Research team Vacancy PhD student, J. Vijverberg, E. van Donk (promoter)
In cooperation with: Dr.J. Nagelkerke (WUR), Prof. Dr.J. Verreth (promoter, WUR)
Contact person J. Vijverberg
Outside funding WOTRO
Objectives: The comparative food web research is a descriptive field study of the same food web studied in the cosms. Measurements and sampling will be carried out in contrasting habitats (i.e. bays differing in degree of eutrophication). The experiments with the enclosures have a two-factorial design with nutrient level (measure of eutrophication) and biomass of Nile perch (measure of fishery pressure) as main factors. Three different levels of eutrophication and 3 levels of Nile perch biomass are established, resulting in nine treatments (at least 3 replicates per treatment). The cosm experiments will give insight in the effects of the increased eutrophication on food web components (detritus, algae, zooplankton, Caridina) and dynamics under different Nile perch biomass treatments. The assessed production and biomass of Caridina is indicative for the Nile perch production. The comparative food web research in contrasting habitats will give the same kind of results as the cosm experiments, but now under more realistic field conditions and the maximum eutrophic state observed in the field will be lower than the highest state applied in the cosms. This cosm-independent information will give insight in the effects of the degree of eutrophication on food web components including the Nile perch biomass stock.
Modelling study to unravel interactions and feedbacks resulting from eutrophication or fishery as most likely factors driving changes in Lake Victoria’s food web (SEDEC-2)
Environmental stress and disease in aquatic ecosystems (GEDIHAP)
Research period 2008-2011
Research team B. Ibelngs, new PhD student, E. van Donk
Contact persons B. Ibelings
Funding ETH/CCES
Objectives: In this proposal we bring together approaches from two different fields, ecotoxicology and evolutionary biology with the aim to comprehend interactions between environmental stress and disease. The following hypotheses are tested experimentally:

1) Environmental stress strengthens the susceptibility to disease.
2) Environmental stress increases virulence.
3) Low genetic diversity of the host enhances susceptibility to disease:
4) Environmental stress reduces host population density, transmission probability of the parasites and severity of disease.
5) Some environmental stress factors affect parasites more than the host, reduce disease.
6) The effects of environmental stress - as outlined under 1 - 5 - may be additive, synergistic or (partially) neutralize each other, depending on the relative strength of effects 1 - 5
7) Organisms gradually adapt to environmental stress, the impact of stress on disease diminishes with time.