TY - JOUR A1 - Bachmann, Jennifer A1 - Heimbach, Tabea A1 - Hassenrück, Christiane A1 - Kopprio, German A. A1 - Iversen, Morten Hvitfeldt A1 - Grossart, Hans-Peter A1 - Gärdes, Astrid T1 - Environmental Drivers of Free-Living vs. Particle-Attached Bacterial Community Composition in the Mauritania Upwelling System JF - Frontiers in microbiology N2 - Saharan dust input and seasonal upwelling along North-West Africa provide a model system for studying microbial processes related to the export and recycling of nutrients. This study offers the first molecular characterization of prokaryotic particle-attached (PA; > 3.0 mu m) and free-living (FL; 0.2-3.0 mu m) players in this important ecosystem during August 2016. Environmental drivers for alpha-diversity, bacterial community composition, and differences between FL and PA fractions were identified. The ultra-oligotrophic waters off Senegal were dominated by Cyanobacteria while higher relative abundances of Alphaproteobacteria, Bacteroidetes, Verrucomicrobia, and Planctomycetes (known particle-degraders) occurred in the upwelling area. Temperature, proxy for different water masses, was the best predictor for changes in FL communities. PA community variation was best explained by temperature and ammonium. Bray Curtis dissimilarities between FL and PA were generally very high and correlated with temperature and salinity in surface waters. Greatest similarities between FL and PA occurred at the deep chlorophyll maximum, where bacterial substrate availability was likely highest. This indicates that environmental drivers do not only influence changes among FL and PA communities but also differences between them. This could provide an explanation for contradicting results obtained by different studies regarding the dissimilarity/similarity between FL and PA communities and their biogeochemical functions. KW - prokaryotes KW - biodiversity KW - microbial ecology KW - alpha diversity KW - Bray Curtis dissimilarity KW - temperature KW - salinity KW - 16S rRNA Illumina amplicon sequencing Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.02836 SN - 1664-302X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - THES A1 - Bergholz, Kolja T1 - Trait-based understanding of plant species distributions along environmental gradients T1 - Zum Verständnis der Verbreitung von Pflanzen entlang von umweltgradienten auf der Basis von funktionellen Eigenschaften N2 - For more than two centuries, plant ecologists have aimed to understand how environmental gradients and biotic interactions shape the distribution and co-occurrence of plant species. In recent years, functional trait–based approaches have been increasingly used to predict patterns of species co-occurrence and species distributions along environmental gradients (trait–environment relationships). Functional traits are measurable properties at the individual level that correlate well with important processes. Thus, they allow us to identify general patterns by synthesizing studies across specific taxonomic compositions, thereby fostering our understanding of the underlying processes of species assembly. However, the importance of specific processes have been shown to be highly dependent on the spatial scale under consideration. In particular, it remains uncertain which mechanisms drive species assembly and allow for plant species coexistence at smaller, more local spatial scales. Furthermore, there is still no consensus on how particular environmental gradients affect the trait composition of plant communities. For example, increasing drought because of climate change is predicted to be a main threat to plant diversity, although it remains unclear which traits of species respond to increasing aridity. Similarly, there is conflicting evidence of how soil fertilization affects the traits related to establishment ability (e.g., seed mass). In this cumulative dissertation, I present three empirical trait-based studies that investigate specific research questions in order to improve our understanding of species distributions along environmental gradients. In the first case study, I analyze how annual species assemble at the local scale and how environmental heterogeneity affects different facets of biodiversity—i.e. taxonomic, functional, and phylogenetic diversity—at different spatial scales. The study was conducted in a semi-arid environment at the transition zone between desert and Mediterranean ecosystems that features a sharp precipitation gradient (Israel). Different null model analyses revealed strong support for environmentally driven species assembly at the local scale, since species with similar traits tended to co-occur and shared high abundances within microsites (trait convergence). A phylogenetic approach, which assumes that closely related species are functionally more similar to each other than distantly related ones, partly supported these results. However, I observed that species abundances within microsites were, surprisingly, more evenly distributed across the phylogenetic tree than expected (phylogenetic overdispersion). Furthermore, I showed that environmental heterogeneity has a positive effect on diversity, which was higher on functional than on taxonomic diversity and increased with spatial scale. The results of this case study indicate that environmental heterogeneity may act as a stabilizing factor to maintain species diversity at local scales, since it influenced species distribution according to their traits and positively influenced diversity. All results were constant along the precipitation gradient. In the second case study (same study system as case study one), I explore the trait responses of two Mediterranean annuals (Geropogon hybridus and Crupina crupinastrum) along a precipitation gradient that is comparable to the maximum changes in precipitation predicted to occur by the end of this century (i.e., −30%). The heterocarpic G. hybridus showed strong trends in seed traits, suggesting that dispersal ability increased with aridity. By contrast, the homocarpic C. crupinastrum showed only a decrease in plant height as aridity increased, while leaf traits of both species showed no consistent pattern along the precipitation gradient. Furthermore, variance decomposition of traits revealed that most of the trait variation observed in the study system was actually found within populations. I conclude that trait responses towards aridity are highly species-specific and that the amount of precipitation is not the most striking environmental factor at this particular scale. In the third case study, I assess how soil fertilization mediates—directly by increased nutrient addition and indirectly by increased competition—the effect of seed mass on establishment ability. For this experiment, I used 22 species differing in seed mass from dry grasslands in northeastern Germany and analyzed the interacting effects of seed mass with nutrient availability and competition on four key components of seedling establishment: seedling emergence, time of seedling emergence, seedling survival, and seedling growth. (Time of) seedling emergence was not affected by seed mass. However, I observed that the positive effect of seed mass on seedling survival is lowered under conditions of high nutrient availability, whereas the positive effect of seed mass on seedling growth was only reduced by competition. Based on these findings, I developed a conceptual model of how seed mass should change along a soil fertility gradient in order to reconcile conflicting findings from the literature. In this model, seed mass shows a U-shaped pattern along the soil fertility gradient as a result of changing nutrient availability and competition. Overall, the three case studies highlight the role of environmental factors on species distribution and co-occurrence. Moreover, the findings of this thesis indicate that spatial heterogeneity at local scales may act as a stabilizing factor that allows species with different traits to coexist. In the concluding discussion, I critically debate intraspecific trait variability in plant community ecology, the use of phylogenetic relationships and easily measured key functional traits as a proxy for species’ niches. Finally, I offer my outlook for the future of functional plant community research. N2 - Seit über 200 Jahre erforschen Ökologen den Einfluss von Umweltgradienten, biotischen Interaktionen und neutralen Prozessen auf die Artenzusammensetzung von Pflanzengemeinschaften. Um generelle Muster und die zugrundeliegenden Mechanismen unabhängig von der gegeben Artenzusammensetzung besser zu verstehen, wurden in den letzten Jahren vermehrt funktionellen Eigenschaften (‚functional traits‘) als methodischen Ansatz genutzt. Es wurde deutlich, dass die bestimmenden Prozesse abhängig von der betrachteten räumlichen Skala sind. Vor allem ist unklar, in wieweit Umweltheterogenität auf kleiner, lokaler Skala die Artenzusammensetzung beeinflusst. Des Weiteren ist Skalenabhängigkeit wichtig um den Einfluss von spezifischen Umweltgradienten, wie Trockenheit oder Bodenfertilität, auf die funktionelle Eigenschaften von Pflanzengemeinschaften zu ermitteln. In der vorliegenden Dissertation untersuche ich in drei unabhängigen, empirischen Studien den Einfluss von Umweltgradienten bzw. Umweltheterogenität auf die funktionellen Eigenschaften von Pflanzengemeinschaften unter besonderer Berücksichtigung der Skalenabhängigkeit. In der ersten Fallstudie prüfe ich welche Faktoren die Artenzusammensetzung in einem semi-ariden Ökosystem (Israel), das von einjährigen Pflanzen dominiert wird, auf lokaler Skala bestimmen. Ich kann zeigen, dass vor allem Arten mit ähnlichen funktionellen Eigenschaften in Mikrohabitaten auftreten, das auf eine Selektion durch Umweltfaktoren hindeutet. Des Weiteren kann ich zeigen, dass mit Zunahme der Umweltheterogenität des Habitats die Diversität der funktionellen Eigenschaften sowie die Artendiversität in den Pflanzengemeinschaften zunehmen. Aus diesen Ergebnissen folgere ich, dass lokale Umweltheterogenität ein wichtiger Faktor für die Koexistenz der Pflanzenarten ist. Im selben Untersuchungsgebiet, untersuche ich in der zweiten Studie die Anpassung von mediterranen Pflanzen entlang eines Niederschlagsgradienten, der den vorausgesagten Niederschlagsveränderungen bis zum Ende dieses Jahrhunderts entspricht. Dafür wurden die funktionellen Eigenschaften von zwei typischen mediterranen Arten in 16 Populationen gemessen. Überraschenderweise zeigten die Arten unterschiedliche Anpassungen entlang des Gradienten, dass auf eine artspezifische Anpassung an Trockenheit hinweist. Des Weiteren wird in der Studie deutlich, dass der Regengradient zwar ein wichtiger, aber kein bestimmender Faktor auf der entsprechenden Skala ist, da ein großer Anteil der intraspezifischen Merkmalsvariation innerhalb der Populationen gefunden wird. In der dritten Studie untersuche ich inwieweit Bodenfertilität die Etablierungswahrscheinlichkeit von Pflanzen mit unterschiedlichen Samenmassen direkt (durch erhöhte Nährstoffverfügbarkeit) und indirekt (durch erhöhte Konkurrenz) beeinflusst. Das Experiment wurde mit 22 Trockenrasenarten aus Nordost Brandenburg durchgeführt. Es zeigte sich, dass der positive Effekt von Samenmasse auf die Etablierungsfähigkeit abhängig von den jeweiligen Bedingungen ist und verschiedene Prozesse während der Etablierungsphase beeinflusst werden. Auf der Basis dieser Ergebnisse und Literatur, stelle ich ein konzeptionelles Model vor, dass widersprüchliche Ergebnisse aus der Literatur synthetisiert. Zusammengenommen zeigen die Ergebnisse meiner Dissertation, dass funktionelle Eigenschaften wichtige Erkenntnisse über die Prozesse liefern, die das Auftreten von Pflanzen und deren Anpassung entlang von Umweltgradienten bestimmen. In der abschließenden Diskussion hinterfrage ich kritisch die Verwendung von intraspezifischer Variabilität funktioneller Eigenschaften in der Gemeinschaftsökologie, Phylogenie als Surrogat für die Nische einer Art und die Standardisierung funktioneller Eigenschaften als methodische Aspekte. Abschließend gebe ich einen Ausblick über zukünftige Pflanzenökologie-Forschung mit funktionellen Eigenschaften. KW - functional ecology KW - plant community KW - species coexistence KW - biodiversity KW - funktionelle Ökologie KW - Pflanzengemeinschaften KW - Koexistenz von Arten KW - Biodiversität Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-426341 ER - TY - JOUR A1 - Darwall, William A1 - Bremerich, Vanessa A1 - De Wever, Aaike A1 - Dell, Anthony I. A1 - Freyhof, Joerg A1 - Gessner, Mark O. A1 - Grossart, Hans-Peter A1 - Harrison, Ian A1 - Irvine, Ken A1 - Jähnig, Sonja C. A1 - Jeschke, Jonathan M. A1 - Lee, Jessica J. A1 - Lu, Cai A1 - Lewandowska, Aleksandra M. A1 - Monaghan, Michael T. A1 - Nejstgaard, Jens C. A1 - Patricio, Harmony A1 - Schmidt-Kloiber, Astrid A1 - Stuart, Simon N. A1 - Thieme, Michele A1 - Tockner, Klement A1 - Turak, Eren A1 - Weyl, Olaf T1 - The alliance for freshwater life BT - a global call to unite efforts for freshwater biodiversity science and conservation JF - Aquatic Conservation: Marine and Freshwater Ecosystems N2 - 1. Global pressures on freshwater ecosystems are high and rising. Viewed primarily as a resource for humans, current practices of water use have led to catastrophic declines in freshwater species and the degradation of freshwater ecosystems, including their genetic and functional diversity. Approximately three-quarters of the world's inland wetlands have been lost, one-third of the 28 000 freshwater species assessed for the International Union for Conservation of Nature (IUCN) Red List are threatened with extinction, and freshwater vertebrate populations are undergoing declines that are more rapid than those of terrestrial and marine species. This global loss continues unchecked, despite the importance of freshwater ecosystems as a source of clean water, food, livelihoods, recreation, and inspiration. 2. The causes of these declines include hydrological alterations, habitat degradation and loss, overexploitation, invasive species, pollution, and the multiple impacts of climate change. Although there are policy initiatives that aim to protect freshwater life, these are rarely implemented with sufficient conviction and enforcement. Policies that focus on the development and management of fresh waters as a resource for people almost universally neglect the biodiversity that they contain. 3. Here we introduce the Alliance for Freshwater Life, a global initiative, uniting specialists in research, data synthesis, conservation, education and outreach, and policymaking. This expert network aims to provide the critical mass required for the effective representation of freshwater biodiversity at policy meetings, to develop solutions balancing the needs of development and conservation, and to better convey the important role freshwater ecosystems play in human well-being. Through this united effort we hope to reverse this tide of loss and decline in freshwater biodiversity. We introduce several short- and medium-term actions as examples for making positive change, and invite individuals, organizations, authorities, and governments to join the Alliance for Freshwater Life. KW - biodiversity KW - conservation evaluation KW - endangered species KW - fish KW - invertebrates KW - macrophytes Y1 - 2018 U6 - https://doi.org/10.1002/aqc.2958 SN - 1052-7613 SN - 1099-0755 VL - 28 IS - 4 SP - 1015 EP - 1022 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Dengler, Jürgen A1 - Wagner, Viktoria A1 - Dembicz, Iwona A1 - Garcia-Mijangos, Itziar A1 - Naqinezhad, Alireza A1 - Boch, Steffen A1 - Chiarucci, Alessandro A1 - Conradi, Timo A1 - Filibeck, Goffredo A1 - Guarino, Riccardo A1 - Janisova, Monika A1 - Steinbauer, Manuel J. A1 - Acic, Svetlana A1 - Acosta, Alicia T. R. A1 - Akasaka, Munemitsu A1 - Allers, Marc-Andre A1 - Apostolova, Iva A1 - Axmanova, Irena A1 - Bakan, Branko A1 - Baranova, Alina A1 - Bardy-Durchhalter, Manfred A1 - Bartha, Sandor A1 - Baumann, Esther A1 - Becker, Thomas A1 - Becker, Ute A1 - Belonovskaya, Elena A1 - Bengtsson, Karin A1 - Benito Alonso, Jose Luis A1 - Berastegi, Asun A1 - Bergamini, Ariel A1 - Bonini, Ilaria A1 - Bruun, Hans Henrik A1 - Budzhak, Vasyl A1 - Bueno, Alvaro A1 - Antonio Campos, Juan A1 - Cancellieri, Laura A1 - Carboni, Marta A1 - Chocarro, Cristina A1 - Conti, Luisa A1 - Czarniecka-Wiera, Marta A1 - De Frenne, Pieter A1 - Deak, Balazs A1 - Didukh, Yakiv P. A1 - Diekmann, Martin A1 - Dolnik, Christian A1 - Dupre, Cecilia A1 - Ecker, Klaus A1 - Ermakov, Nikolai A1 - Erschbamer, Brigitta A1 - Escudero, Adrian A1 - Etayo, Javier A1 - Fajmonova, Zuzana A1 - Felde, Vivian A. A1 - Fernandez Calzado, Maria Rosa A1 - Finckh, Manfred A1 - Fotiadis, Georgios A1 - Fracchiolla, Mariano A1 - Ganeva, Anna A1 - Garcia-Magro, Daniel A1 - Gavilan, Rosario G. A1 - Germany, Markus A1 - Giladi, Itamar A1 - Gillet, Francois A1 - Giusso del Galdo, Gian Pietro A1 - Gonzalez, Jose M. A1 - Grytnes, John-Arvid A1 - Hajek, Michal A1 - Hajkova, Petra A1 - Helm, Aveliina A1 - Herrera, Mercedes A1 - Hettenbergerova, Eva A1 - Hobohm, Carsten A1 - Huellbusch, Elisabeth M. A1 - Ingerpuu, Nele A1 - Jandt, Ute A1 - Jeltsch, Florian A1 - Jensen, Kai A1 - Jentsch, Anke A1 - Jeschke, Michael A1 - Jimenez-Alfaro, Borja A1 - Kacki, Zygmunt A1 - Kakinuma, Kaoru A1 - Kapfer, Jutta A1 - Kavgaci, Ali A1 - Kelemen, Andras A1 - Kiehl, Kathrin A1 - Koyama, Asuka A1 - Koyanagi, Tomoyo F. A1 - Kozub, Lukasz A1 - Kuzemko, Anna A1 - Kyrkjeeide, Magni Olsen A1 - Landi, Sara A1 - Langer, Nancy A1 - Lastrucci, Lorenzo A1 - Lazzaro, Lorenzo A1 - Lelli, Chiara A1 - Leps, Jan A1 - Loebel, Swantje A1 - Luzuriaga, Arantzazu L. A1 - Maccherini, Simona A1 - Magnes, Martin A1 - Malicki, Marek A1 - Marceno, Corrado A1 - Mardari, Constantin A1 - Mauchamp, Leslie A1 - May, Felix A1 - Michelsen, Ottar A1 - Mesa, Joaquin Molero A1 - Molnar, Zsolt A1 - Moysiyenko, Ivan Y. A1 - Nakaga, Yuko K. A1 - Natcheva, Rayna A1 - Noroozi, Jalil A1 - Pakeman, Robin J. A1 - Palpurina, Salza A1 - Partel, Meelis A1 - Paetsch, Ricarda A1 - Pauli, Harald A1 - Pedashenko, Hristo A1 - Peet, Robert K. A1 - Pielech, Remigiusz A1 - Pipenbaher, Natasa A1 - Pirini, Chrisoula A1 - Pleskova, Zuzana A1 - Polyakova, Mariya A. A1 - Prentice, Honor C. A1 - Reinecke, Jennifer A1 - Reitalu, Triin A1 - Pilar Rodriguez-Rojo, Maria A1 - Rolecek, Jan A1 - Ronkin, Vladimir A1 - Rosati, Leonardo A1 - Rosen, Ejvind A1 - Ruprecht, Eszter A1 - Rusina, Solvita A1 - Sabovljevic, Marko A1 - Maria Sanchez, Ana A1 - Savchenko, Galina A1 - Schuhmacher, Oliver A1 - Skornik, Sonja A1 - Sperandii, Marta Gaia A1 - Staniaszek-Kik, Monika A1 - Stevanovic-Dajic, Zora A1 - Stock, Marin A1 - Suchrow, Sigrid A1 - Sutcliffe, Laura M. E. A1 - Swacha, Grzegorz A1 - Sykes, Martin A1 - Szabo, Anna A1 - Talebi, Amir A1 - Tanase, Catalin A1 - Terzi, Massimo A1 - Tolgyesi, Csaba A1 - Torca, Marta A1 - Torok, Peter A1 - Tothmeresz, Bela A1 - Tsarevskaya, Nadezda A1 - Tsiripidis, Ioannis A1 - Tzonev, Rossen A1 - Ushimaru, Atushi A1 - Valko, Orsolya A1 - van der Maarel, Eddy A1 - Vanneste, Thomas A1 - Vashenyak, Iuliia A1 - Vassilev, Kiril A1 - Viciani, Daniele A1 - Villar, Luis A1 - Virtanen, Risto A1 - Kosic, Ivana Vitasovic A1 - Wang, Yun A1 - Weiser, Frank A1 - Went, Julia A1 - Wesche, Karsten A1 - White, Hannah A1 - Winkler, Manuela A1 - Zaniewski, Piotr T. A1 - Zhang, Hui A1 - Ziv, Yaron A1 - Znamenskiy, Sergey A1 - Biurrun, Idoia T1 - GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands JF - Phytocoenologia N2 - GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board. KW - biodiversity KW - European Vegetation Archive (EVA) KW - Eurasian Dry Grassland Group (EDGG) KW - grassland vegetation KW - GrassPlot KW - macroecology KW - multi-taxon KW - nested plot KW - scale-dependence KW - species-area relationship (SAR) KW - sPlot KW - vegetation-plot database Y1 - 2018 U6 - https://doi.org/10.1127/phyto/2018/0267 SN - 0340-269X VL - 48 IS - 3 SP - 331 EP - 347 PB - Cramer CY - Stuttgart ER - TY - THES A1 - Kettner, Marie Therese T1 - Microbial colonization of microplastic particles in aquatic systems T1 - Mikrobielle Besiedlung von Mikroplastik-Partikeln in aquatischen Systemen N2 - The continuously increasing pollution of aquatic environments with microplastics (plastic particles < 5 mm) is a global problem with potential implications for organisms of all trophic levels. For microorganisms, trillions of these floating microplastics particles represent a huge surface area for colonization. Due to the very low biodegradability, microplastics remain years to centuries in the environment and can be transported over thousands of kilometers together with the attached organisms. Since also pathogenic, invasive, or otherwise harmful species could be spread this way, it is essential to study microplastics-associated communities. For this doctoral thesis, eukaryotic communities were analyzed for the first time on microplastics in brackish environments and compared to communities in the surrounding water and on the natural substrate wood. With Illumina MiSeq high-throughput sequencing, more than 500 different eukaryotic taxa were detected on the microplastics samples. Among them were various green algae, dinoflagellates, ciliates, fungi, fungal-like protists and small metazoans such as nematodes and rotifers. The most abundant organisms was a dinoflagellate of the genus Pfiesteria, which could include fish pathogenic and bloom forming toxigenic species. Network analyses revealed that there were numerous interaction possibilities among prokaryotes and eukaryotes in microplastics biofilms. Eukaryotic community compositions on microplastics differed significantly from those on wood and in water, and compositions were additionally distinct among the sampling locations. Furthermore, the biodiversity was clearly lower on microplastics in comparison to the diversity on wood or in the surrounding water. In another experiment, a situation was simulated in which treated wastewater containing microplastics was introduced into a freshwater lake. With increasing microplastics concentrations, the resulting bacterial communities became more similar to those from the treated wastewater. Moreover, the abundance of integrase I increased together with rising concentrations of microplastics. Integrase I is often used as a marker for anthropogenic environmental pollution and is further linked to genes conferring, e.g., antibiotic resistance. This dissertation gives detailed insights into the complexity of prokaryotic and eukaryotic communities on microplastics in brackish and freshwater systems. Even though microplastics provide novel microhabitats for various microbes, they might also transport toxigenic, pathogenic, antibiotic-resistant or parasitic organisms; meaning their colonization can pose potential threats to humans and the environment. Finally, this thesis explains the urgent need for more research as well as for strategies to minimize the global microplastic pollution. N2 - Die stetig steigende Verschmutzung der Gewässer mit Mikroplastik (Plastikteilchen < 5 mm) ist ein weltweites Umweltproblem und wirkt sich potentiell auf Organismen aller trophischen Ebenen aus. Für Mikroorganismen stellen Billionen dieser schwimmenden Mikroplastik-partikel eine riesige Fläche zur Besiedlung dar. Aufgrund der sehr schlechten Abbaubarkeit verbleibt Mikroplastik Jahre bis Jahrhunderte in der Umwelt und kann samt der angehefteten Organismen über mehrere Tausend Kilometer weit transportiert werden. Da sich darüber auch pathogene, invasive oder anderweitig gefährliche Arten verbreiten könnten, ist es essentiell, die Mikroplastik-assoziierten Gemeinschaften zu untersuchen. Im Rahmen dieser Doktorarbeit wurden erstmals die eukaryotischen Gemeinschaften auf Mikroplastik in Brackwasser-Habitaten analysiert und mit Gemeinschaften aus dem umgebenden Wasser und auf dem natürlichen Substrat Holz verglichen. Mit Illumina MiSeq Hochdurchsatz-Sequenzierungs-Verfahren wurde ermittelt, dass über 500 verschiedene eukaryotische Taxa auf den Mikroplastikproben vorkamen. Dazu gehörten unterschiedliche Grünalgen, Dinoflagellaten, Ciliaten, Pilze, pilz-ähnliche Protisten und kleine Metazoen wie Fadenwürmer oder Rädertierchen. Am häufigsten kamen Dinoflagellaten der Gattung Pfiesteria vor, zu der möglicherweise fischpathogene und toxische Algenblüten-bildende Arten gehören könnten. Netzwerk-Analysen zeigten, dass es auf Mikroplastik eine Vielzahl von Interaktionsmöglichkeiten zwischen den vorhandenen Eukaryoten und Prokaryoten gibt. Die Zusammensetzungen der Eukaryoten-Gemeinschaften auf Mikroplastik unterschieden sich signifikant von jenen auf Holz und im umgebenden Wasser, aber auch zwischen den verschiedenen Probenahme-Standorten. Die Mikroplastikproben wiesen im Vergleich zu Wasser und Holz die geringste Biodiversität auf. In einem weiteren Experiment wurde simuliert, dass Mikroplastik-haltiges Wasser aus dem Ablauf einer Kläranlage in einen See eingeleitet wird. Bei hohen Mikroplastikkonzentrationen reicherten sich besonders Bakterien aus dem Kläranlagenablauf an. Zudem hatten die Bakteriengemeinschaften auf Mikroplastik ein signifikant erhöhtes Vorkommen eines bestimmten genetischen Markers (Integrase I), welcher auf anthropogene Umweltverschmutzung hindeutet, sowie mit Genen verknüpft ist, die z. B. Antibiotika-Resistenzen übertragen können. Die Versuchsergebnisse dieser Doktorarbeit zeigen einerseits, wie komplex und vielseitig das mikrobielle Leben auf Mikroplastik sein kann, andererseits könnten diese Partikel aber auch Transportvehikel für toxische, pathogene, antibiotika-resistente oder parasitäre Organismen darstellen. Somit birgt ihre Besiedlung potentielle Gefahren für Mensch und Umwelt. Darüber hinaus weist diese Arbeit auf dringenden Forschungsbedarf hin und verdeutlicht die Notwendigkeit der Eindämmung der globalen Mikroplastik-Verschmutzung. KW - microplastics KW - eukaryotes KW - sequencing KW - fungi KW - biofilm KW - biodiversity KW - Biodiversität KW - Biofilm KW - Eukaryoten KW - Pilze KW - Mikroplastik KW - Sequenzierung Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-418854 ER -