Helmut Hillebrand

Carl von Ossietzky Universität Oldenburg, Oldenburg, Lower Saxony, Germany

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Publications (136)838.66 Total impact

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    ABSTRACT: Humans are modifying the availability of nutrients such as nitrogen (N) and phosphorus (P), and it is therefore important to understand how these nutrients, independently or in combination, influence the growth and nutrient content of primary producers. Using meta-analysis of 118 field and laboratory experiments in freshwater, marine and terrestrial ecosystems, we tested hypotheses about co-limitation of N and P by comparing the effects of adding N alone, P alone, and both N and P together on internal N (e.g. %N, C:N) and P (e.g. %P, C:P) concentrations in autotroph communities. In particular, we tested the following predictions. First, if only one nutrient was limiting, addition of that nutrient should decrease the concentration of the other nutrient, but addition of the non-limiting nutrient would have no effect on the internal concentration of the limiting nutrient. If community co-limitation was occurring then addition of either nutrient should result in a decrease in the internal concentration of the other nutrient. Community co-limitation could also result in no change – or even an increase – in N concentrations in response to P addition if P stimulated growth of N fixers. Finally, if biochemically dependent co-limitation was occurring, addition of a limiting nutrient would not decrease, and could even increase, the concentration of the other, co-limited nutrient. We found no general evidence for the decrease in the internal concentration of one nutrient due to addition of another nutrient. The one exception to this overall pattern was marine systems, where N addition decreased internal P concentrations. In contrast, P addition increased internal N concentrations across all experiments, consistent with co-limitation. These results have important implications for understanding the roles that N and P play in controlling producer growth and internal nutrient accumulation as well as for managing the effects of nutrient enrichment in ecosystems.
    Oikos 10/2014; · 3.33 Impact Factor
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    ABSTRACT: Background/Question/Methods Can diversity simultaneously affect a wide variety of different ecosystem functions? Despite first studies analyzing effects of diversity on multiple ecosystem functions having revealed stronger diversity effects than studies looking at single functions this questions remains little studied. As an often used approach, the number of species contributing to functioning has been shown to increases with the number of studies, years, or functions considered. Yet, conclusions based on the number of contributing species have been criticized and recent methodological advances have proposed alternatives. Here we used multivariate statistics to investigate the relationship between plant diversity and multifunctionality. We based our analysis on more than 100 functions measured along an experimental gradient of grassland plant diversity ranging from 1 to 60 species. The set of ecosystem functions included various above- and below-ground processes, e.g. cover, LAI, plant biomass, soil nutrients, and abundance data of plant-associated invertebrates such as earthworms, pollinators and herbivores. Using principle component analysis based on the value of each function in each plot we investigated (1) correlations and trade-offs between functions, (2) the functional fingerprint and (3) the overall level of expressed functioning of each plot and (4) the relationships of all these parameters to plant species richness. Results/Conclusions Relationships between the investigated functions spanned the whole spectrum from strong positive correlation (association) to almost perfect negative correlation (trade-off). Intermediate between these extremes, a large number of functions were independent from each other, thus showed correlations around zero. Consequently, a large number of axes (23) was needed to explain at least 75% of the variation observed in the multifunctional space. Plant diversity correlated strongly with the first principle component axis (r=0.67, p<<0.001) while axes of higher order did not show any relationships with plant diversity. This indicates that especially the functions associated with the first principal component axis change along the plant diversity gradient. To calculate an index of multifunctionality, we extendend the “averaging approach” from single functions to a multivariate measure by summing scores for the first 30 principle component axes. The resulting multifunctionality index increased highly significantly with plant diversity from predominantly negative values at low diversity to positive values at high diversity (F1,76=8.26; p=0.005). Thus, plots of high diversity supported more functions at above average levels than low diversity plots. Results from our multivariate approach are compared to other proposed approaches to measure multifunctionality.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Trichocyst-enriched fractions were isolated from the marine dinophyte Prorocentrum micans. Transmission electron microscopy revealed that most of the trichocysts were discharged and had elongated to long filaments. Some trichocysts were still condensed. Fragments of discharged trichocysts measured up to 20 μm in length and 260 nm in width, those still condensed measured up to 1 μm in width and 16 μm in length. A distinct banding pattern with a transversal periodicity of approximately 16-18 nm and a periodic longitudinal striation of 3-4 nm could be measured along the trichocyst filaments. At higher magnifications, a fragile, alveolated, net-like organisation became obvious which resembled the one shown for the trichocysts of ciliates. When trichocyst-enriched fractions were treated with sodium dodecyl sulfate and centrifuged subsequently, no trichocysts were registered any longer in the sodium dodecyl sulfate-insoluble fraction by electron microscopy. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of trichocyst-enriched fractions and of the SDS-soluble fractions revealed a protein banding pattern which was dominated by polypeptides of 50-30, 12.5, and approximately 8.5 kDa. The polypeptide banding pattern deviated significantly from those registered for ejectisomes of cryptophytes and of the prasinophyte Pyramimonas grossii, for the Reb polypeptides which constitute the R-bodies of Caedibacter taeniospiralis, and also from the banding pattern of trichocysts of Paramecium. An antiserum directed against trichocysts of Paramecium did not cross-react with the polypeptides present in the trichocyst-enriched fraction of Prorocentrum micans.
    Protoplasma 07/2014; · 2.86 Impact Factor
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    Nils Guelzow, Merten Dirks, Helmut Hillebrand
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    ABSTRACT: Disentangling the mechanisms that maintain the stability of communities and ecosystem properties has become a major research focus in ecology in the face of anthropogenic environmental change. Dispersal plays a pivotal role in maintaining diversity in spatially subdivided communities, but only a few experiments have simultaneously investigated how dispersal and environmental fluctuation affect community dynamics and ecosystem stability. We performed an experimental study using marine phytoplankton species as model organisms to test these mechanisms in a metacommunity context. We established three levels of dispersal and exposed the phytoplankton to fluctuating light levels, where fluctuations were either spatially asynchronous or synchronous across patches of the metacommunity. Dispersal had no effect on diversity and ecosystem function (biomass), while light fluctuations affected both evenness and community biomass. The temporal variability of community biomass was reduced by fluctuating light and temporal beta diversity was influenced interactively by dispersal and fluctuation, whereas spatial variability in community biomass and beta diversity were barely affected by treatments. Along the establishing gradient of species richness and dominance, community biomass increased but temporal variability of biomass decreased, thus highest stability was associated with species-rich but highly uneven communities and less influenced by compensatory dynamics. In conclusion, both specific traits (dominance) and diversity (richness) affected the stability of metacommunities under fluctuating conditions.
    Oecologia 07/2014; · 3.01 Impact Factor
  • Silke Ammermann, Helmut Hillebrand, Erhard Rhiel
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    ABSTRACT: Ejectisome fragments were isolated from the prasinophyte Pyramimonas grossii and subjected to different treatments, i.e. Percoll density gradient centrifugation, incubation at pH 2.5 or at pH 10.8, or incubation in 6 M guanidine hydrochloride. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that Percoll density gradient centrifugation did not improve the purity of the ejectisome fragment-enriched fractions. The ejectisome fragments withstood pH 2.5 and pH 10.8 treatment, and no loosely bound polypeptides became detached. The disintegration of ejectisome fragments was achieved in 6 M guanidine hydrochloride, and reassembly into filamentous, ejectisome-like structures occurred after dialysis against distilled water. Fractions enriched either in ejectisome fragments or in reconstituted ejectisome-like structures were dominated by three polypeptides with relative molecular weights of approximately 12.5-19 kDa and two additional polypeptides of 23 and 26 kDa. A polyclonal antiserum directed against an ejectisome fragment-enriched fraction weakly cross-reacted with these polypeptides, and no significant immuno-labelling of ejectisome fragments was registered. A positive immuno-label was achieved using immunoglobulin (IgG) fractions which were gained by selectively incubating nitrocellulose stripes of these polypeptides with the antiserum.
    European Journal of Protistology 06/2014; · 1.51 Impact Factor
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    ABSTRACT: Ökologische Stöchiometrie (ecological stoichiometry, ES) hat sich in den letzten beiden Jahrzehnten zu einer der grundlegenden Theorien der Umweltwissenschaften und der Biologie entwickelt. Durch den Vergleich von elementarer Zusammensetzung von Organismen und ihren Ressourcenansprüchen mit der relativen Verfügbarkeit der Ressourcen sagt ES Prozesse auf allen Organisationsebenen von subzellulären Strukturen bis hin zu Ökosystemen voraus. Allerdings wurde ES bisher selten angewandt um den Zusammenhang zwischen Biodiversität und Ökosystemfunktion zu verstehen, obwohl ES ideal dazu geeignet wäre, da es sowohl Vorhersagen zu Prozessen macht, die Biodiversität beeinflussen, als auch zu Materieflüssen und–transformationen, auf denen wichtige Ökosystemfunktionen basieren. In diesem Artikel untersuchen wir den Zusammenhang dieser beiden Forschungsfelder und zeigen zukünftige Forschungsfelder anhand von drei Themen auf: i) die stöchiometrische Aspekte der Treiber des Biodiversitätswandels, ii) stöchiometrische Grundlagen des Zusammenhangs zwischen Biodiversität und Produktivität, iii) potentielle Interaktionen zwischen Biodiversität und Stöchiometrie im Nahrungsnetzkontext.
    Basic and Applied Ecology 06/2014; · 2.70 Impact Factor
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    ABSTRACT: Es wird angenommen, dass funktionelle Pflanzenmerkmale verantwortlich sind für beobachtete Effekte von Pflanzendiversität auf Ökosystemfunktionen, wodurch sich der Fokus der Biodiversitätsforschung von der Betrachtung der Effekte von Pflanzenartenzahlen hin zu der Betrachtung von Pflanzenmerkmalen in einer Gemeinschaft erweitert hat. Die Berücksichtigung von funktionellen Pflanzenmerkmalen hilft möglichweise zu verstehen, wie der Verlust von Arten Ökosystemprozesse beeinflusst. Unseres Wissens wurde jedoch die funktionelle Ähnlichkeit verschiedener Pflanzenarten zueinander noch nie als Grundlage für ein Grasland-Biodiversitätsexperiment genutzt. Wir präsentieren den theoretischen Hintergrund, das experimentelle Design und erste Ergebnisse eines sogenannten ‚Trait-Based Biodiversity Experiments’ (TBE), welches 2010 im Rahmen des Jena Experimentes etabliert wurde und bei welchem direkt die funktionelle Diversität von Pflanzeneigenschaften manipuliert wurde. Mithilfe einer Hauptkomponentenanalyse wurden sechs Pflanzenmerkmale von 60 Graslandarten analysiert, die bedeutend für Ressourcenaufnahme und -nutzung sind. Dabei bildeten die Pflanzenarten, die entlang zweier unabhängiger Achsen angeordnet waren, Gradienten in ihrer funktionellen Ähnlichkeit, die als Basis für das Design des TBE dienten. Auf neu angelegten Versuchsflächen etablierten wir Pflanzengemeinschaften mit unterschiedlicher Pflanzenartenzahl, die sich in ihrer räumlichen und zeitlichen funktionellen Komplementarität unterscheiden. Das neuartige Design des TBE erlaubt es uns in Zukunft den relativen Einfluss von Selektions- und Komplementaritätseffekten auf Ökosystemprozesse zu bestimmen und ermöglicht die mechanistische Erforschung der Konsequenzen von vereinfachten Lebensgemeinschaften.
    Basic and Applied Ecology 05/2014; · 2.70 Impact Factor
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    ABSTRACT: Changes in plant diversity have consequences for higher trophic levels, e.g., higher plant diversity can enhance the reproduction and fitness of plant-associated insects. This response of higher trophic levels potentially depends on diversity-related changes in both resource quantity (abundance) and quality (nutritional content). The availability of elemental nutrients in plant resources is one aspect of nutritional quality, but has rarely been addressed as a pathway relating plant diversity to associated insects. Using the experimental plant diversity gradient of a large biodiversity grassland project, the Jena-Experiment, we analyzed the %C, %N and %P and the molar ratios of those elements (C:N, C:P and N:P) in a pollinating bee, Chelostoma distinctum, and an herbivorous grasshopper, Chorthippus parallelus, reared on plots of different plant diversity. Insects showed higher content of C, N and P (% dry mass), and lower C:N and C:P ratios than plants. C:N ratios were significantly higher in grasshoppers than in bees and higher in females than in males of both species. Increasing plant species richness increased the C:N ratio of male bees and female grasshoppers. In both groups, stoichiometry was positively related to plant stoichiometry (male bees: C:P and N:P; grasshoppers: C:N and N:P). Path analysis revealed that diversity-driven changes in plant elemental composition can have consequences for abundance and chemical composition of higher trophic levels, with different responses of the two functional groups.
    Basic and Applied Ecology 03/2014; · 2.70 Impact Factor
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    ABSTRACT: Ecosystem functioning is affected by horizontal (within trophic groups) and vertical (across trophic levels) biodiversity. Theory predicts that the effects of vertical biodiversity depend on consumer specialization. In a microcosm experiment, we investigated ciliate consumer diversity and specialization effects on algal prey biovolume, evenness and composition, and on ciliate biovolume production. The experimental data was complemented by a process-based model further analyzing the ecological mechanisms behind the observed diversity effects. Overall, increasing consumer diversity had no significant effect on prey biovolume or evenness. However, consumer specialization affected the prey community. Specialist consumers showed a stronger negative impact on prey biovolume and evenness than generalists. The model confirmed that this pattern was mainly driven by a single specialist with a high per capita grazing rate, consuming the two most productive prey species. When these were suppressed, the prey assemblage became dominated by a less productive species, consequently decreasing prey biovolume and evenness. Consumer diversity increased consumer biovolume, which was stronger for generalists than for specialists and highest in mixed combinations, indicating that consumer functional diversity, i.e. more diverse feeding strategies, increased resource use efficiency. Overall, our results indicate that consumer diversity effects on prey and consumers strongly depend on species-specific growth and grazing rates, which may be at least equally important as consumer specialization in driving consumer diversity effects across trophic levels.
    Oikos 03/2014; · 3.33 Impact Factor
  • Helmut Hillebrand, Jessica Gurevitch
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    ABSTRACT: A recurrent question in meta-analyses is the validity of including both field and laboratory studies in a single analysis, given the differences in characteristics such as the duration or size of these experiments. In particular, are field studies consistently more variable, longer in duration, or do they differ from laboratory studies in other important ways? We examined these questions using an unusually large and comprehensive data set on grazing effects on benthic microalgae, consisting of 865 experiments including both field and lab studies and using marine, lotic or lentic communities of small benthic primary producers. We found there was greater variation in field than laboratory studies, but that this difference explained only 0.5% of the variance in the coefficient of variation. Field studies were longer, on average, than laboratory studies, but experiments in the two systems did not differ consistently in other ecological or design parameters. Thus, the common assumption that field studies have higher variances than laboratory studies, while true, explained only a tiny proportion of the heterogeneity in variation. Therefore, perhaps surprisingly, any conclusions from research syntheses would be unlikely to be affected by consistent differences in variance (or other parameters we examined) between the laboratory and field studies.
    Oikos 03/2014; · 3.33 Impact Factor
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    ABSTRACT: Studies of experimental grassland communities have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change. Here we analyse diversity-stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.
    Nature 02/2014; · 38.60 Impact Factor
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    ABSTRACT: Freshwater biodiversity loss potentially disrupts ecosystem services related to water quality and may negatively impact ecosystem functioning and temporal community turnover. We analysed a data set containing phytoplankton and zooplankton community data from 131 lakes through 9 years in an agricultural region to test predictions that plankton communities with low biodiversity are less efficient in their use of limiting resources and display greater community turnover (measured as community dissimilarity). Phytoplankton resource use efficiency (RUE = biomass per unit resource) was negatively related to phytoplankton evenness (measured as Pielou's evenness), whereas zooplankton RUE was positively related to phytoplankton evenness. Phytoplankton and zooplankton RUE were high and low, respectively, when Cyanobacteria, especially Microcystis sp., dominated. Phytoplankton communities displayed slower community turnover rates when dominated by few genera. Our findings, which counter findings of many terrestrial studies, suggest that Cyanobacteria dominance may play important roles in ecosystem functioning and community turnover in nutrient-enriched lakes.
    Ecology Letters 01/2014; · 17.95 Impact Factor
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    ABSTRACT: Loss of plant diversity influences essential ecosystem processes as aboveground productivity, and can have cascading effects on the arthropod communities in adjacent trophic levels. However, few studies have examined how those changes in arthropod communities can have additional impacts on ecosystem processes caused by them (e.g. pollination, bioturbation, predation, decomposition, herbivory). Therefore, including arthropod effects in predictions of the impact of plant diversity loss on such ecosystem processes is an important but little studied piece of information. In a grassland biodiversity experiment, we addressed this gap by assessing aboveground decomposer and herbivore communities and linking their abundance and diversity to rates of decomposition and herbivory. Path analyses showed that increasing plant diversity led to higher abundance and diversity of decomposing arthropods through higher plant biomass. Higher species richness of decomposers, in turn, enhanced decomposition. Similarly, species-rich plant communities hosted a higher abundance and diversity of herbivores through elevated plant biomass and C:N ratio, leading to higher herbivory rates. Integrating trophic interactions into the study of biodiversity effects is required to understand the multiple pathways by which biodiversity affects ecosystem functioning.
    PLoS ONE 01/2014; 9(9):e106529. · 3.53 Impact Factor
  • Dorothee Hodapp, Dietmar Kraft, Helmut Hillebrand
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    ABSTRACT: One of the most controversially discussed topics in current biodiversity-ecosystem function research is the transfer of results from experimental and theoretical studies to natural ecosystems. At the same time, monitoring data on biodiversity are requested as key indicators for the state of an ecosystem in most environmental evaluation frameworks. We analyse two monitoring data sets comprising information on abundance and biomass of macrozoobenthos communities in the German Wadden Sea in order to evaluate how much information monitoring data on biodiversity provide concerning ecosystem functioning and what implications this information (or the lack thereof) has for future monitoring programmes. Our results show a positive correlation between number of species of macrozoobenthos and its standing stock. Despite differences in overall biomass and individual size in different functional groups, this correlation remained consistent for different feeding guilds and therefore is likely to be independent of certain species traits. Moreover, functional turnover analyses indicate that increasing species richness is needed to maintain biomass levels over increasing periods of time. Whereas our data thus corroborate predictions from theory, we could not determine any causal relationships, because monitoring data commonly include only vague proxies for very few functional parameters, in our case standing biomass as a proxy for production. As to the use of diversity as an indicator for ecosystem functioning, we advise that management decisions are to be based on verified causal relationships and therefore strongly suggest the general incorporation of unambiguous proxies for functional parameters in the measuring campaigns of monitoring programmes.
    Biodiversity and Conservation 01/2014; 23(2). · 2.26 Impact Factor
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    ABSTRACT: In time of scarcity of fossil energies, microalgae are attracting interest as a potential source of renewable energy due to their high growth rates and potential high lipid contents. Additionally, cultivation may be an abatement measure to remove surplus nutrients from eutrophicated ecosystems. At present, microalgal cultivations for biomass production are run mainly in monocultures, which are easily contaminated with competing microalgae or grazers. Furthermore, hetero-trophic bacteria are highly abundant and may strongly reduce the yield in the target microalgae through competition for nutrients. In three laboratory experiments, we tested whether heterotrophic flagellates (Oxyrrhis marina and Cafeteria roenbergensis) can make nutrients bound in bacteria available for marine diatoms (Coscinodiscus granii and Odontella sinensis) and can shift the competition for inorganic nutrients towards the microalgae. Cultures were run with and without flagellates, under different conditions: without an external carbon source, in presence of organic matter (barley grains) or biogas wastewater. The presence of flagellates had a posi-tive effect on microalgal growth, but this was context and species specific. The presence of the flagellates affected the maximum algal growth rates (r) especially in Coscinodiscus granii. A maximal biomass increase (29.93±2.98 %) (mean ± standard deviation, n=3) was observed for Coscinodiscus granii in F/2 + Si medium. Furthermore, although the flagellates were attributed to the detrital fraction, their presence resulted in a significant reduc-tion of detritus. In conclusion, heterotrophic flagellates have the potential to increase nutrient use efficiency especially in algae bioreactors with slow-growing large phytoplankton taxa. This effect may be particularly relevant in organic polluted water.
    Journal of Applied Phycology 01/2014; · 2.33 Impact Factor
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    ABSTRACT: The non-indigenous diatom Mediopyxis helysia was first observed in spring 2009 in the backbarrier tidal flats of Spiekeroog, North Sea (53°45´01.00´´N and 007°40´16.30´´) and has dominated spring blooms throughout the years 2009–2011. It also prevailed during the remainder of the season and – compared to 2009 – the total biovolume during spring blooms decreased by 36% and phytoplankton species richness as well as evenness declined concomitantly. M. helysia's rapid establishment led to the questions: (1) Which advantageous traits does this species possess? (2) Which environmental conditions facilitate its expansion? Therefore, we here amend our field observations with an experiment, in which artificial communities were cultured under six different combinations of Si and N concentrations in presence and absence of M. helysia for one month. The relative biomasses of M. helysia with regard to different nutrient concentrations in an artificial community were examined with exclusion of grazing. At the end of the experiment, the phytoplankton community was dominated by the only lab culture, the chlorophyte Dunaliella salina, but M. helysia was the most successful diatom. Its presence changed the community composition irrespective of the chosen Si and N concentrations. M. helysia significantly diminished chlorophytes and dinoflagellate percentages, whereas diatom growth was supported and total biovolume increased in the experiment. Moreover, M. helysia enhanced the evenness in the artificial community. The broad persistence of M. helysia under different resource conditions may have contributed to the successful establishment of M. helysia in the North Sea and its dominance throughout the year.
    Journal of Sea Research. 01/2014;
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    ABSTRACT: Recent climate warming is expected to affect phytoplankton biomass and diversity in marine ecosystems. Temperature can act directly on phytoplankton (e.g. rendering physiological processes) or indirectly due to changes in zooplankton grazing activity. We tested experimentally the impact of increased temperature on natural phytoplankton and zooplankton communities using indoor mesocosms and combined the results from different experimental years applying a meta-analytic approach. We divided our analysis into three bloom phases to define the strength of temperature and zooplankton impacts on phytoplankton in different stages of bloom development. Within the constraints of an experiment, our results suggest that increased temperature and zooplankton grazing have similar effects on phytoplankton diversity, which are most apparent in the post-bloom phase, when zooplankton abundances reach the highest values. Moreover, we observed changes in zooplankton composition in response to warming and initial conditions, which can additionally affect phytoplankton diversity, because changing feeding preferences of zooplankton can affect phytoplankton community structure. We conclude that phytoplankton diversity is indirectly affected by temperature in the post-bloom phase through changing zooplankton composition and grazing activities. Before and during the bloom, however, these effects seem to be overruled by temperature enhanced bottom-up processes such as phytoplankton nutrient uptake.
    Journal of Sea Research 01/2014; 85:359–364. · 1.86 Impact Factor
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    ABSTRACT: Landscape connectivity can increase the capacity of communities to maintain their function when environments change by promoting the immigration of species or populations with adapted traits. However, high immigration may also restrict fine tuning of species compositions to local environmental conditions by homogenizing the community. Here we demonstrate that dispersal generates such a tradeoff between maximizing local biomass and the capacity of model periphyton metacommunities to recover after a simulated heat wave. In non-disturbed metacommunities, dispersal decreased the total biomass by preventing differentiation in species composition between the local patches making up the metacommunity. On the contrary, in metacommunities exposed to a realistic summer heat wave, dispersal promoted recovery by increasing the biomass of heat tolerant species in all local patches. Thus, the heat wave reorganized the species composition of the metacommunities and after an initial decrease in total biomass by 38.7%, dispersal fueled a full recovery of biomass in the restructured metacommunities. Although dispersal may decrease equilibrium biomass, our results highlight that connectivity is a key requirement for the response diversity that allows ecological communities to adapt to climate change through species sorting.
    Oikos 01/2014; · 3.33 Impact Factor
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    ABSTRACT: Human alterations to nutrient cycles1, 2 and herbivore communities3, 4, 5, 6, 7 are affecting global biodiversity dramatically2. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems8, 9. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.
    Nature 01/2014; advance online publication. · 38.60 Impact Factor
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    Helmut Hillebrand, Jessica Gurevitch
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    ABSTRACT: The checklist for methods reporting is available at: http://www.wiley-docs.com/Checklist_for_reporting_experimental_details.pdf
    Ecology Letters 09/2013; · 17.95 Impact Factor

Publication Stats

4k Citations
838.66 Total Impact Points

Top Journals


  • 2008–2014
    • Carl von Ossietzky Universität Oldenburg
      • Department of Chemistry and Biology of the Marine Environment (ICBM)
      Oldenburg, Lower Saxony, Germany
    • Arizona State University
      • School of Life Sciences
      Mesa, AZ, United States
    • Marine Biological Association of the UK
      Plymouth, England, United Kingdom
  • 2012
    • Cary Institute of Ecosystem Studies
      Millbrook, New York, United States
    • USGS National Wetlands Research Center
      Lafayette, Louisiana, United States
  • 2000–2012
    • Uppsala University
      • Department of Ecology and Genetics
      Uppsala, Uppsala, Sweden
  • 2011
    • Utah State University
      Logan, Ohio, United States
    • Universitätsklinikum Jena
      Jena, Thuringia, Germany
    • Iowa State University
      • Department of Ecology, Evolution and Organismal Biology
      Ames, IA, United States
  • 2007–2011
    • University of Helsinki
      • • Department of Environmental Sciences
      • • Department of Biological and Environmental Sciences
      Helsinki, Province of Southern Finland, Finland
    • Leibniz-Institut für Meereswissenschaften an der Universität Kiel
      Kiel, Schleswig-Holstein, Germany
  • 2005–2011
    • University of Cologne
      • Botanical Institute
      Köln, North Rhine-Westphalia, Germany
  • 2006–2009
    • University of California, Santa Barbara
      • Department of Ecology, Evolution, and Marine Biology
      Santa Barbara, CA, United States
    • Massachusetts Institute of Technology
      • Department of Civil and Environmental Engineering
      Cambridge, MA, United States
  • 2006–2008
    • University of British Columbia - Vancouver
      • Department of Zoology
      Vancouver, British Columbia, Canada
  • 2004
    • Christian-Albrechts-Universität zu Kiel
      Kiel, Schleswig-Holstein, Germany
  • 2002
    • Dalhousie University
      • Department of Biology
      Halifax, Nova Scotia, Canada