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Fischer R.,Carl von Ossietzky University | Giebel H.-A.,Carl von Ossietzky University | Ptacnik R.,WasserCluster Lunz Biologische Station GmbH
Marine Ecology Progress Series | Year: 2017

Empirical and theoretical evidence predicts that mixotrophic bacterivores dominate over specialized heterotrophic bacterivores and specialist photoautotrophs under conditions of high light and low loss rates. Here we extend this concept towards nutrient limitation and ask whether the identity of the limiting nutrient affects the competition of mixotrophs with their specialist competitors. Due to their photosynthetic machinery, mixotrophs should have higher cellular N contents than heterotrophs and, following this assumption, a higher demand for N. Conversely, heterotrophs, with their potential high growth rates compared to mixotrophs, may have a higher demand for P ('growth rate hypothesis'). Simplified, mixotrophs should be more prone to N-limitation, while heterotrophs should be more prone to P-limitation. We tested these predictions in artificial food webs studying the competitive success of mixotrophic bacterivores under a range of light intensities and loss rates and under either P- or N-limitation. Under low-light conditions, mixotrophs were more successful than heterotrophs under P-limitation, whereas the heterotrophs were more successful under N-limitation. At higher light intensity, mixotrophs had an advantage over photoautotrophs, due to the acquisition of nutrients ingested with prey. Overall, the effects of the limiting nutrient on the competitive success of mixotrophs were stronger under conditions already unfavorable for mixotrophs (low light). Further, our results suggest that communities dominated by mixotrophs might have low and relatively stable seston C:nutrient ratios. The results presented here supplement existing data well and help to define the ecological niche of mixo - trophic protists. © Inter-Research 2017.


Grant
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: INFRAIA-01-2016-2017 | Award Amount: 10.00M | Year: 2017

Experimentation in mesocosms is arguably the single most powerful approach to obtain a mechanistic quantitative understanding of ecosystem-level impacts of stressors in complex systems, especially when embedded in long-term observations, theoretical models and experiments conducted at other scales. AQUACOSM builds on an established European network of mesocosm research infrastructures (RI), the FP7 Infra project MESOAQUA (2009-2012), where 167 users successfully conducted 74 projects. AQUACOSM greatly enhances that network on pelagic marine systems in at least 3 ways: first by expanding it to 10 freshwater (rivers and lakes), 2 brackish and 2 benthic marine facilities, and by involving 2 SMEs and reaching out to more, thereby granting effective transnational access to world-leading mesocosm facilities to >340 users on >11500 days; second, by integrating scattered know-how between freshwater and marine RI; and third, by uniting aquatic mesocosm science in an open network beyond the core consortium, with industry involved in an ambitious innovation process, to promote ground-breaking developments in mesocosm technology, instrumentation and data processing. A new dimension of experimental ecosystem science will be reached by coordinated mesocosm experiments along transects from the Mediterranean to the Arctic and beyond salinity boundaries. These efforts will culminate in a joint research activity (JRA) to assess aquatic ecosystem responses across multiple environmental gradients to a selected climate-related key stressor with repercussions for ecosystem services. Overall, AQUACOSM will fill a global void by forging an integrated freshwater and marine research infrastructure network. Long-term sustainability is sought through assessing governance models based on science priorities and economic innovation opportunities. Linkages to and synergies with ESFRI RI and other large initiatives are ensured by AQUACOSM partners and Advisory Board members in those programs.


Grant
Agency: European Commission | Branch: FP7 | Program: CSA-CA | Phase: ENV.2013.6.5-2 | Award Amount: 1.17M | Year: 2013

The aim of this project is develop new instruments and tools that will enhance environmental research and promote innovation in Danube Region, including the Danube Delta and the Black Sea. Importantly, the new instruments and tools do not start ab initio but will build on existing projects covering multiple source of funding (public, private or PPP), whether national, regional or European which will be identified and clustered. The project will undertake a critical analysis of what has been achieved so far in the region and will build upon results of achievements to-date, to design innovative solutions to strengthen knowledge transfer in this area. This will be achieved by gathering top level representatives of the academia and business communities as well as decision makers, specialized in various sectors of integrated management of the Danube Black Sea macrosystem. The project will be structured on the three main pillars of Research and Innovation (i. Science and Innovation Agenda, ii. Research Infrastructures and iii. Human Capital) and their relation to the three principal categories of stakeholder: i. Policy and Decision Makers, ii. Business / Industry community and iii. Academia. The specific objectives of this project are to: 1. critically analyse the achievements in integrated river- delta sea management in the Danube Region, 2. understand links between the achievements, deliverables and results of the work performed. 3. Define a set of instruments to enhance environmental research and innovation in Danube Region. The ultimate deliverable will be a toolbox of instruments which will yield 1. a strategic research agenda, 2. a concept and detailed plan of the distributed research infrastructure both for the Danube Black Sea Macrosystem and 3. Proposals for an integrated educational program to be implemented at a regional level in the immediate future, with the full cooperation of partners from Danube - Black Sea Macrosystem.


PubMed | CSIC - Institute of Marine Sciences, RAS Shirshov Institute of Oceanology, University of Bergen, WasserCluster Lunz Biologische Station GmbH and 5 more.
Type: | Journal: Scientific reports | Year: 2016

Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.


Ejarque E.,WasserCluster Lunz Biologische Station GmbH | Ejarque E.,University of Vienna | Ejarque E.,Saint Petersburg State University | Abakumov E.,Saint Petersburg State University
Solid Earth | Year: 2016

Arctic soils contain large amounts of organic matter which, globally, exceed the amount of carbon stored in vegetation biomass and in the atmosphere. Recent studies emphasise the potential sensitivity for this soil organic matter (SOM) to be mineralised when faced with increasing ambient temperatures. In order to better refine the predictions about the response of SOM to climate warming, there is a need to increase the spatial coverage of empirical data on SOM quantity and quality in the Arctic area. This study provides, for the first time, a characterisation of SOM from the Gydan Peninsula in the Yamal Region, Western Siberia, Russia. On the one hand, soil humic acids and their humification state were characterised by measuring the elemental composition and diversity of functional groups using solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy. Also, the total mineralisable carbon was measured. Our results indicate that there is a predominance of aliphatic carbon structures, with a minimal variation of their functional-group composition both regionally and within soil depth. This vertical homogeneity and low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Mineralisation rates were found to be independent of SOM quality, and to be mainly explained solely by the total carbon content. Overall, our results provide further evidence on the sensitivity that the soils of Western Siberia may have to increasing ambient temperatures and highlight the important role that this region can play in the global carbon balance under the effects of climate warming. © Author(s) 2016.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: ENV.2007.2.1.2.2. | Award Amount: 2.92M | Year: 2008

The overall objective of the WETwin project is to enhance the role of wetlands in basin-scale integrated water resources management, with the aim of improving the community service functions while conserving good ecological status. Strategies will be worked out for: utilizing the drinking water supply and sanitation potentials of wetlands for the benefit of people living in the basin, while maintaining (and improving as much as possible) the ecosystem functions adapting wetland management to changing environmental conditions integrating wetlands into river basin management improving stakeholder participation and capacity building with the aim of supporting sustainable wetland management. The project will work on twinned case study wetlands from Africa, South America and Europe. Management solutions will be worked out for these wetlands with the aim of supporting the achievement of the above objectives. Involvement of local stakeholders into the planning process will play a crucial role. Knowledge and experiences gained from these case studies will be summarized in general guidelines in order to support achieving project objectives on global scale. The project also aims at supporting the global exchange of expertise on wetland management. Stakeholder participation, capacity building and expertise exchange will be supported by a series of stakeholder and twinning workshops.


Chaparro G.,University of Buenos Aires | Chaparro G.,WasserCluster Lunz Biologische Station GmbH | Fontanarrosa M.S.,University of Buenos Aires | O'Farrell I.,University of Buenos Aires
Wetlands | Year: 2016

We analyzed zooplankton colonization and succession following a temporary drought in a vegetated lake from a floodplain wetland of the Lower Paraná River (Argentina). We took samples of zooplankton and phytoplankton at four habitats of the lake characterized by the presence-absence of emergent or free-floating macrophytes along a 18-month period after the drought. Microzooplankton dominated along the study and macrozooplankton showed seasonal increments in cold seasons. Temporal patterns of broad taxonomic zooplankton groups were associated to hydrology-driven factors, like changes in water depth, conductivity and edible phytoplankton and seasonal changes and not related with free-floating plants. Nevertheless, spatial and temporal patterns of species composition were closely linked to the dynamics of free-floating plants. A clear shift from pelagic to littoral zooplankton taxa was registered when free-floating plants colonized. This study expands the knowledge on the composition and dynamics of zooplankton from floodplain lakes after the disturbance caused by a severe drought. Our results highlight the influence of water level fluctuations as drivers of zooplankton abundance and the joint effect of seasonal changes and free-floating plant dynamics on zooplankton species composition and richness. © 2015, Society of Wetland Scientists.


Ouyang X.,Griffith University | Ouyang X.,Sichuan Zhonghuanlixin Environmental Protection Consulting Co. | Ouyang J.,Jimei University | Guo F.,WasserCluster Lunz Biologische Station GmbH | Guo F.,Chinese Research Academy of Environmental Sciences
Computers and Chemical Engineering | Year: 2016

The use of adsorption methods to recover vitamin B12 (VB12) from wastewater has been increasingly studied. However, there is a lack of knowledge on optimization of the methods. This study established a feedback network to evaluate alternatives regarding VB12 adsorption from wastewater. The network comprises environmental, economic and technological criteria and their feedbacks. Based on the network, the fuzzy matter-element theory was integrated with an analytical network process to rank the alternatives. Among five alternatives, activated carbon with KOH as activation media was suggested to be the optimal alternative for VB12 recycling from wastewater, while mesoporous activated carbon fibre was the least preferred alternative. Particularly, the adsorption technology reusing biomass ranked second to the optimal alternative, and has great application potential due to low costs and biological waste reuse. Sensitivity analysis does show that the ranking of alternatives was robust and was not subject to the change in weight. © 2016 Elsevier Ltd


Plotner W.A.,Carl von Ossietzky University | Hillebrand H.,Carl von Ossietzky University | Ptacnikova R.,Carl von Ossietzky University | Ptacnikova R.,WasserCluster Lunz Biologische Station GmbH | And 2 more authors.
Journal of Applied Phycology | Year: 2014

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, heterotrophic 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 positive 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 reduction 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. © 2014, Springer Science+Business Media Dordrecht.


Grant
Agency: European Commission | Branch: H2020 | Program: MSCA-IF-EF-ST | Phase: MSCA-IF-2014-EF | Award Amount: 178.16K | Year: 2016

Plankton occupy a key position in aquatic trophic webs, and today, a highly relevant topic lies ahead in assessing its global change-mediated shifts, with implications for the functioning of aquatic systems. Mixotrophic chrysophytes are prevailing elements of phytoplankton in oligo- and mesotrophic lakes. Their contribution is predicted to increase with climate warming, which imply serious consequences for pelagic trophic efficiency and ecosystem services e.g. fish production. However, our current knowledge on the nutritional quality and bottom-up effect of chrysophytes is insufficient. CHRYSOWEB aims to reveal their effects on zooplankton secondary production and diversity in a multi-disciplinary approach, which will significantly contribute to the understanding of carbon flow and nutrient cycling in alpine lakes under global change. Laboratory feeding experiments will be combined with field observations to quantify species-specific responses of relevant zooplankton taxa to chrysophytes. The underlying mechanisms will be biochemically analysed in algae and consumers. The host, WasserCluster Lunz (WCL) is a leading limnological institute in Central Europe with cutting-edge infrastructure and outstanding research performance. My supervisor, Dr Robert Ptacnik (leader of AquaScale working group, WCL) has excellent background in plankton ecology and experimental systems. The biochemical part will be performed in cooperation with Dr Martin Kainz (leader of LIPTOX working group, WCL). I will additionally benefit from the international cooperation with Prof Herwig Stibor (LMU Munich; place of secondment). CHRYSOWEB will produce front-line and timely inter-disciplinary results and enhance my future perspectives to become an independent researcher by broadening my expertise both conceptually and methodologically. The inspiring working environment, high-quality infrastructure, excellent supervision and my personal motivation guarantee the successful outcome of the project.

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