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Heteren, Netherlands

Bauer S.,Swiss Ornithological Institute | Bauer S.,Netherlands Institute of Ecology | Hoye B.J.,University of Colorado at Boulder | Hoye B.J.,Deakin University
Science | Year: 2014

Animal migrations span the globe, involving immense numbers of individuals from a wide range of taxa. Migrants transport nutrients, energy, and other organisms as they forage and are preyed upon throughout their journeys. These highly predictable, pulsed movements across large spatial scales render migration a potentially powerful yet underappreciated dimension of biodiversity that is intimately embedded within resident communities. We review examples from across the animal kingdom to distill fundamental processes by which migratory animals influence communities and ecosystems, demonstrating that they can uniquely alter energy flow, food-web topology and stability, trophic cascades, and the structure of metacommunities. Given the potential for migration to alter ecological networks worldwide, we suggest an integrative framework through which community dynamics and ecosystem functioning may explicitly consider animal migrations. Source

Mendes R.,Laboratory of Environmental Microbiology | Garbeva P.,Netherlands Institute of Ecology | Raaijmakers J.M.,Wageningen University
FEMS Microbiology Reviews | Year: 2013

Microbial communities play a pivotal role in the functioning of plants by influencing their physiology and development. While many members of the rhizosphere microbiome are beneficial to plant growth, also plant pathogenic microorganisms colonize the rhizosphere striving to break through the protective microbial shield and to overcome the innate plant defense mechanisms in order to cause disease. A third group of microorganisms that can be found in the rhizosphere are the true and opportunistic human pathogenic bacteria, which can be carried on or in plant tissue and may cause disease when introduced into debilitated humans. Although the importance of the rhizosphere microbiome for plant growth has been widely recognized, for the vast majority of rhizosphere microorganisms no knowledge exists. To enhance plant growth and health, it is essential to know which microorganism is present in the rhizosphere microbiome and what they are doing. Here, we review the main functions of rhizosphere microorganisms and how they impact on health and disease. We discuss the mechanisms involved in the multitrophic interactions and chemical dialogues that occur in the rhizosphere. Finally, we highlight several strategies to redirect or reshape the rhizosphere microbiome in favor of microorganisms that are beneficial to plant growth and health. In this review, we focus on the frequency, diversity and activities of beneficial ('the good'), plant pathogenic ('the bad') and human pathogenic ('the ugly') microorganisms in the rhizosphere and how they impact on health and disease. Specific attention is given to mechanisms involved in multitrophic interactions and chemical dialogues that occur in the rhizosphere. Finally, we discuss strategies to re-direct or re-shape the rhizosphere microbiome in favour of those microbes that are beneficial to plant growth and health. © 2013 Federation of European Microbiological Societies. Source

Stal L.J.,Netherlands Institute of Ecology
Ecological Engineering | Year: 2010

The properties and behavior of intertidal marine sediments cannot be understood without taking their biology into account. Biological factors are important for the stability and erosion threshold of intertidal sediments as well as for sediment transport. In this paper I focus on intertidal sediments that are colonized and dominated by phototrophic microorganisms and their impact on the morphodynamics and sediment stabilization. The emphasis is on epipelic diatoms. These organisms exude copious amounts of extracellular polymeric substances (EPS) that may contribute to the stability of the sediment by gluing and binding. I review the factors that lead to the development of such microphytobenthic communities and the processes that lead to the exudation of EPS and its fate in intertidal mudflats. Epipelic diatoms exude EPS partly as the result of unbalanced growth. Extraction of EPS from cultures of epipelic diatoms yields two operational fractions. While one fraction contains largely neutral EPS, which may serve as a carbon- and energy reserve for the organism, the other is acidic and more recalcitrant to degradation. The latter EPS fraction is therefore predominant in the muddy sediment and may be responsible for increasing the erosion threshold. However, since extracted EPS alone is incapable of increasing the erosion threshold, diatoms are apparently actively involved in the structuring of the biofilm matrix. Therefore, sediment stabilization cannot be attributed simply to EPS alone. © 2009 Elsevier B.V. All rights reserved. Source

Schaper S.V.,Netherlands Institute of Ecology
The American naturalist | Year: 2012

Timing of reproduction in temperate-zone birds is strongly correlated with spring temperature, with an earlier onset of breeding in warmer years. Females adjust their timing of egg laying between years to be synchronized with local food sources and thereby optimize reproductive output. However, climate change currently disrupts the link between predictive environmental cues and spring phenology. To investigate direct effects of temperature on the decision to lay and its genetic basis, we used pairs of great tits (Parus major) with known ancestry and exposed them to simulated spring scenarios in climate-controlled aviaries. In each of three years, we exposed birds to different patterns of changing temperature. We varied the timing of a temperature change, the daily temperature amplitude, and the onset and speed of a seasonal temperature rise. We show that females fine-tune their laying in response to a seasonal increase in temperature, whereas mean temperature and daily temperature variation alone do not affect laying dates. Luteinizing hormone concentrations and gonadal growth in early spring were not influenced by temperature or temperature rise, possibly posing a constraint to an advancement of breeding. Similarities between sisters in their laying dates indicate genetic variation in cue sensitivity. These results refine our understanding of how changes in spring climate might affect the mismatch in avian timing and thereby population viability. Source

Bodelier P.L.E.,Netherlands Institute of Ecology
Current Opinion in Environmental Sustainability | Year: 2011

Recent dynamics and uncertainties in global methane budgets necessitate research of controls of sources and sinks of atmospheric methane. Production of methane by methanogenic archaea in wetlands is a major source while consumption by methane oxidizing bacteria in upland soils is a major sink. Methane formation as well as consumption is affected by nitrogenous fertilizers as has been studied intensively. This review synthesizes the results of these studies which are contradictory and await mechanistic explanations. These can be found in the community composition and the traits of the microbes involved in methane cycling. Molecular microbial investigations, use of stable isotope labeling techniques, discoveries and isolation of new species and pathways offer new insight into interactions between nitrogen and methane cycling. © 2011 Elsevier B.V. Source

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